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60 results on '"Sergey I. Nikitenko"'

1. Ultrasonically assisted conversion of uranium trioxide into uranium( vi ) intrinsic colloids

Author

Christophe Den Auwer, Xavier Le Goff, Olivier Diat, Thomas Dumas, Cyril Micheau, Manon Cot-Auriol, Philippe Moisy, Matthieu Virot, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Etude de la Matière en Mode Environnemental (L2ME), Institut de Chimie de Nice (ICN), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Ions aux Interfaces Actives (L2IA), Commission des méthodes d'analyse du CEA (CETAMA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Chemistry, Inorganic chemistry, chemistry.chemical_element, Nanoparticle, 02 engineering and technology, Uranium, 010402 general chemistry, 021001 nanoscience & nanotechnology, Uranyl, complex mixtures, 01 natural sciences, 0104 chemical sciences, Inorganic Chemistry, chemistry.chemical_compound, 13. Climate action, Uranium trioxide, Oxidizing agent, [CHIM]Chemical Sciences, Reactivity (chemistry), Leaching (metallurgy), 0210 nano-technology, Schoepite
Abstract

Under oxidizing conditions, the corrosion of spent nuclear fuel may lead to the leaching of radionuclides including soluble uranyl-based species. The speciation of the generated chemical forms is complex and the related potential formation of colloidal species appears surprisingly poorly reported in the literature. Their formation could however contribute significantly to the mobility of radionuclides in the environment. A better knowledge in the speciation and reactivity of these species appears particularly relevant. This study describes the preparation and characterization of intrinsic uranium(VI) colloids from amorphous and crystalline UO3 in pure water assisted by 20 kHz ultrasound. In the presence of carbon monoxide preventing the sonochemical formation of hydrogen peroxide, ultrasonic treatment boosts the conversion of UO3 powder into (meta-)schoepite precipitates and yields very stable and notably concentrated uranium(VI) nanoparticles in the liquid phase. Using HR-TEM, SAXS and XAS techniques, we confirmed that the colloidal suspension is composed of quasi-spherical nanoparticles measuring ca. 3.8 ± 0.3 nm and exhibiting a schoepite-like crystallographic structure. The proposed method demonstrates the possible formation of environmentally relevant U(VI) colloidal nanoparticles appearing particularly interesting for the preparation of reference systems in the absence of added ions and capping agents.

Published
2021
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2. Impact of bubble coalescence in the determination of bubble sizes using a pulsed US technique: Part 2 – Effect of the nature of saturating gas

Author

Rachel Pflieger, Sergey I. Nikitenko, Geoffrey Audiger, Muthupandian Ashokkumar, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), School of Chemistry [Melbourne], Faculty of Science [Melbourne], University of Melbourne-University of Melbourne, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Acoustics and Ultrasonics, Bubble, QC221-246, O2, 02 engineering and technology, Coalescence, 010402 general chemistry, 01 natural sciences, Inorganic Chemistry, Sonoluminescence, Xe, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, Original Research Article, Bubble size, Dissolution, QD1-999, Coalescence (physics), He, Air, Organic Chemistry, Acoustics. Sound, N2, Radius, Mechanics, 021001 nanoscience & nanotechnology, 3. Good health, 0104 chemical sciences, Pulse (physics), Chemistry, Pulsed ultrasound, Cavitation, Ultrasonic sensor, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology
Abstract

Highlights • Bubble ambient radii are determined for He, Xe, O2, N2 and air in water at 362 kHz. • They are close to 1 µm for He, N2 and air, and around 2.8–3.1 µm for O2, Ar and Xe. • The extent of coalescence is quantified. It strongly depends on the gas nature., Knowledge on cavitation bubble size distribution, ambient radius of bubbles is of interest for many applications that include therapeutic and diagnostic medicine. It however becomes a hard quest when increasing the ultrasonic frequency, when direct observation of bubble dynamics is no longer possible. An indirect method based on the estimation of the bubble dissolution time under pulsed ultrasound (362 kHz) is used here under optimized conditions to derive ambient radii of cavitation bubbles in water saturated with He, Ar, Xe, O2, N2 and air: 3.0 µm for Ar, 1.2 µm for He, 3.1 µm for Xe, 2.8 µm for O2, around 1 µm for N2 and air. If the pulse on-time is increased, bubble coalescence occurs, the extent of which is rather limited for Ar but extremely high for He or N2.

Published
2021
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3. Impact of bubble coalescence in the determination of bubble sizes using a pulsed US technique: Part 1 – Argon bubbles in water

Author

Léa Gravier, Julia Bertolo, Sergey I. Nikitenko, Rachel Pflieger, Muthupandian Ashokkumar, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), University of Melbourne, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM), Bio21 Molecular Science & Biotechnology Institute [Melbourne] (School of Chemistry), Faculty of Science [Melbourne], University of Melbourne-University of Melbourne, and This work was supported by the program for scientific mobility of the French Embassy in Australia (833171 E, 2014) and by the University of Melbourne (PRC0988 UCAB, 2015)

Subjects
Acoustics and Ultrasonics, Bubble, QC221-246, chemistry.chemical_element, 02 engineering and technology, Coalescence, 010402 general chemistry, 01 natural sciences, Sonochemistry, Inorganic Chemistry, Physics::Fluid Dynamics, Sonoluminescence, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, Original Research Article, Bubble size, SDS, QD1-999, Ar, Coalescence (physics), Argon, Organic Chemistry, Acoustics. Sound, Mechanics, Radius, 021001 nanoscience & nanotechnology, Sound power, 0104 chemical sciences, Volumetric flow rate, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Chemistry, chemistry, Pulsed ultrasound, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology
Abstract

Highlights • An experimental method for determination of bubble sizes is thoroughly studied. • If conditions are not optimized, bubble coalescence leads to too big sizes. • The presence of a standing wave enhances coalescence. • Conditions for measurement of the ambient size of cavitation bubbles are determined. • An ambient radius of 2.9–3.0 µm is derived for Ar-saturated water at 362 kHz., A powerful experimental approach to measure the size distribution of bubbles active in sonoluminescence and/or sonochemistry is a technique based on pulsed ultrasound and sonoluminescence emission. While it is an accepted technique, it is still lacking an understanding of the effect of various experimental parameters, including the duration of the pulse on-time, the nature of the dissolved gas, the presence of a gas flow rate, etc. The present work, focusing on Ar-saturated water sonicated at 362 kHz, shows that increasing the pulse on-time leads to the measurement of coalesced bubbles. Reducing the on-time to a minimum and/or adding sodium dodecyl sulfate to water allows to reducing coalescence so that natural active cavitation bubble sizes can be measured. A radius of 2.9–3.0 µm is obtained in Ar-saturated water at 362 kHz. The effects of acoustic power and possible formation of a standing-wave on coalescence and measured bubble sizes are discussed.

Published
2021
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4. Tailoring Noble Metal-Free Ti@TiO2 Photocatalyst for Boosting Photothermal Hydrogen Production

Author

Tony Chave, Sara El Hakim, Stéphanie Roualdes, Sergey I. Nikitenko, Amr A. Nada, Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut Européen des membranes (IEM), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Hydrogen, Titanium suboxide, Nanoparticle, chemistry.chemical_element, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, Nanomaterials, Sonohydrothermal, Photocatalysis, Hydrogen production, [CHIM.MATE]Chemical Sciences/Material chemistry, Photothermal therapy, 021001 nanoscience & nanotechnology, Nanocrystalline material, 0104 chemical sciences, Chemical engineering, chemistry, engineering, Noble metal, 0210 nano-technology
Abstract

In this work, we provide new insights into the design of Ti@TiO2photocatalyst with enhanced photothermal activity in the process of glycerol reforming. Ti@TiO2nanoparticles have been obtained by sonohydrothermal treatment of titanium metal nanoparticles in pure water. Variation of sonohydrothermal temperature allows controlling nanocrystalline TiO2shell on Ti0surface. At 100 < T < 150°C formation of TiO2NPs occurs mostly by crystallization of Ti(IV) amorphous species and oxidation of titanium suboxide Ti3O presented at the surface of Ti0nanoparticles. At T > 150°C, TiO2is also formed by oxidation of Ti0with overheated water. Kinetic study highlights the importance of TiO2nanocrystalline shell for H2generation. Electrochemical impedance spectroscopy points out more efficient electron transfer for Ti@TiO2nanoparticles in correlation with photocatalytic data. The apparent activation energy, Ea= (25–31) ± 5 kJ·mol−1, assumes that photothermal effect arises from diffusion of glycerol oxidation intermediates or from water dynamics at the surface of catalyst. Under the heating, photocatalytic H2emission is observed even in pure water.

Published
2021
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5. Sonochemical decontamination of magnesium and magnesium-zirconium alloys in mild conditions

Author

Matthieu Virot, Rachel Pflieger, Sergey I. Nikitenko, Ran Ji, Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), CEA- Saclay (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Cladding (metalworking), Environmental Engineering, Materials science, Health, Toxicology and Mutagenesis, Sonication, Oxalic acid, chemistry.chemical_element, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, Corrosion, chemistry.chemical_compound, Environmental Chemistry, [CHIM]Chemical Sciences, Waste Management and Disposal, Brucite, Magnesium, Zirconium alloy, Human decontamination, 021001 nanoscience & nanotechnology, Pollution, 0104 chemical sciences, Chemical engineering, chemistry, engineering, 0210 nano-technology
Abstract

International audience; UNGG cladding nuclear wastes constitute a huge volume of Mg-based materials that raises economic and safety concerns, particularly due to their radioactivity coupled to the potential generation of H$_2$ gas under deep underground disposal. Their significant decontamination would result in more secure and less expensive storage, with a better containment of the separated long-lived radioisotopes that could enter in a classical channel. Sonication of genuine UNGG cladding materials and simulants at 345 kHz in 0.01 M oxalic acid solution (20 °C) allowed the structuring of their surfaces with the observation of homogeneously distributed craters of 20–40 $\mu$m in diameter. After a thorough characterization and comparison of the ultrasound effects generated at the surface, the various samples were artificially contaminated and characterized before sonication. The complete and rapid sonochemical decontamination of Mg-based materials was then observed, in addition to the removal of the carbon layer promoting corrosion on the inner UNGG cladding. The extension of sonication allows the neo-formed brucite (Mg(OH)$_2$) and zirconium-based phases to accumulate on the surface, thus contributing in a slight but continuous surface recontamination process. This phenomenon results from the re-adsorption of uranyl cations from the solution which can be avoided by optimizing the duration of treatment.

Published
2021
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6. Sonocatalytic degradation of EDTA in the presence of Ti and Ti@TiO2 nanoparticles

Author

Sara El Hakim, Sergey I. Nikitenko, Tony Chave, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Anatase, Materials science, Acoustics and Ultrasonics, Sonication, lcsh:QC221-246, Nanoparticle, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Sonochemistry, Inorganic Chemistry, lcsh:Chemistry, Sonocatalysis, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, Partial oxidation, Titanium nanoparticles, Heterogeneous catalysis, Aqueous solution, [SDE.IE]Environmental Sciences/Environmental Engineering, Organic Chemistry, EDTA, [CHIM.CATA]Chemical Sciences/Catalysis, 021001 nanoscience & nanotechnology, Hybrid Advanced Oxidation Processes involving Ultrasound, Nanocrystalline material, 0104 chemical sciences, chemistry, lcsh:QD1-999, 13. Climate action, lcsh:Acoustics. Sound, 0210 nano-technology, [CHIM.OTHE]Chemical Sciences/Other, Titanium, Nuclear chemistry
Abstract

Highlights • Nanoparticles of metallic titanium, Ti0, exhibit high sonocatalytic activity. • Ti0 nanoparticles are inactive without ultrasound. • Coating of Ti0 with TiO2 reduces sonocatalytic activity. • Oxygen plays a crucial role in a sonocatalytic activity of Ti0 nanoparticles., The sonocatalytic degradation of EDTA (C0 = 5 10−3 M) in aqueous solutions was studied under 345 kHz (Pac = 0.25 W mL−1) ultrasound at 22–51 °C, Ar/20%O2, Ar or air, and in the presence of metallic titanium (Ti0) or core-shell Ti@TiO2 nanoparticles (NPs). Ti@TiO2 NPs have been obtained using simultaneous action of hydrothermal conditions (100–214 °C, autogenic pressure P = 1.0–19.0 bar) and 20 kHz ultrasound, called sonohydrothermal (SHT) treatment, on Ti0 NPs in pure water. Ti0 is composed of quasi-spherical particles (30–150 nm) of metallic titanium coated with a metastable titanium suboxide Ti3O. SHT treatment at 150–214 °C leads to the oxidation of Ti3O and partial oxidation of Ti0 and formation of nanocrystalline shell (10–20 nm) composed of TiO2 anatase. It was found that Ti0 NPs do not exhibit catalytic activity in the absence of ultrasound. Moreover, Ti0 NPs remain inactive under ultrasound in the absence of oxygen. However, significant acceleration of EDTA degradation was achieved during sonication in the presence of Ti0 NPs and Ar/20%O2 gas mixture. Coating of Ti0 with TiO2 nanocrystalline shell reduces sonocatalytic activity. Pristine TiO2 anatase nanoparticles do not show a sonocatalytic activity in studied system. Suggested mechanism of EDTA sonocatalytic degradation involves two reaction pathways: (i) sonochemical oxidation of EDTA by OH•/HO2• radicals in solution and (ii) EDTA oxidation at the surface of Ti0 NPs in the presence of oxygen activated by cavitation event. Ultrasonic activation most probably occurs due to the local heating of Ti0/O2 species at cavitation bubble/solution interface.

Published
2021
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7. Photocatalytic and Sonocatalytic Degradation of EDTA and Rhodamine B over Ti0 and Ti@TiO2 Nanoparticles

Author

Sergey I. Nikitenko, Tony Chave, Sara El Hakim, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Anatase, Materials science, organic pollutants, Nanoparticle, Ethylenediaminetetraacetic acid, 02 engineering and technology, TP1-1185, 010402 general chemistry, 01 natural sciences, Catalysis, chemistry.chemical_compound, photothermal, sonocatalysis, Oxidizing agent, Rhodamine B, titanium, Physical and Theoretical Chemistry, QD1-999, [SDE.IE]Environmental Sciences/Environmental Engineering, Chemical technology, EDTA, [CHIM.CATA]Chemical Sciences/Catalysis, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Chemistry, chemistry, 13. Climate action, Photocatalysis, Degradation (geology), nanoparticles, 0210 nano-technology, [CHIM.OTHE]Chemical Sciences/Other, photocatalysis, Nuclear chemistry, rhodamine B, environmental remediation
Abstract

Herein, we report a comparative study of photocatalytic (Xe-lamp) and sonocatalytic (345 kHz power ultrasound) degradation of Ethylenediaminetetraacetic acid (EDTA) and Rhodamine B (RhB) in the presence of Ti0 and Ti@TiO2 core-shell nanoparticles (NPs). Ti@TiO2 NPs have been obtained by sonohydrothermal treatment (20 kHz, 200 °C) of commercially available Ti0 NPs in pure water. The obtained material is composed of quasi-spherical Ti0 particles (30–150 nm) coated by 5–15 nm crystals of anatase. In contrast to pristine TiO2, the Ti@TiO2 NPs exhibit the extend photo response from UV to NIR light region due to the light absorption by nonplasmonic Ti core. EDTA can be oxidized effectively by photocatalysis in the presence of Ti@TiO2 NPs. By contrast, air passivated Ti0 nanoparticles was found to be inactive in the photocatalytic process for both EDTA and RhB. Photocatalytic degradation of EDTA over Ti@TiO2 NPs exhibits strong photothermal effect, which has been attributed to the higher yield of oxidizing radicals produced by light at higher bulk temperature. The efficiency of RhB photocatalytic degradation depends strongly on RhB concentration. At [RhB] ≥ 1 × 10−3 M, its photocatalytic degradation is not feasible due to a strong self-absorption. At lower concentrations, RhB photocatalytic degradation is observed, but at lower efficiency compared to EDTA. We found that the efficient sonochemical degradation of RhB does not require the presence of any catalysts. For both processes, EDTA and RhB, sonochemical and photocatalytic processes are more effective in the presence of Ar/O2 gas mixture compared to pure Ar. The obtained results suggest that the choice of the optimal technology for organic pollutants degradation can be determined by their optical and complexing properties.

Published
2021
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8. Sonochemical dissolution of nanoscale ThO2 and partial conversion into a thorium peroxo sulfate

Author

Laura Bonato, Matthieu Virot, Xavier Le Goff, Philippe Moisy, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Etude de la Matière en Mode Environnemental (L2ME), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Acoustics and Ultrasonics, Organic Chemistry, Inorganic chemistry, Thorium, chemistry.chemical_element, Sulfuric acid, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Inorganic Chemistry, chemistry.chemical_compound, chemistry, Cavitation, Chemical Engineering (miscellaneous), Environmental Chemistry, [CHIM]Chemical Sciences, Radiology, Nuclear Medicine and imaging, Sulfate, 0210 nano-technology, Dissolution, Nanoscopic scale
Abstract

International audience; The influence of the sample morphology and experimental conditions towards the sonochemical dissolution of nanoscale ThO 2 samples in sulfuric acid media is described. Significant sonochemical dissolution rates and yields are observed at 20 kHz under Ar/O 2 atmosphere in dilute 0.5 M H 2 SO 4 at room temperature, contrasting with the generally-reported high refractory behavior for ThO 2. The dissolution of ThO 2 combines the physical effects driven by acoustic cavitation phenomenon, the complexing affinity of Th(IV) in sulfuric medium and the sonochemical generation of H 2 O 2. These sonochemical conditions further allow the observation of the partial conversion of ThO 2 into a scarce Th(IV) peroxo sulfate with 1D morphology resulting from one or both following processes: dissolution/ reprecipitation or formation of an intermediate Th(IV) surface complex.

Published
2020
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9. Physical and chemical characterization of shock-induced cavitation

Author

Sergey I. Nikitenko, Tony Chave, Patrick Da Costa, Hugo Dutilleul, Laureanne Parizot, M. E. Gálvez, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut Jean Le Rond d'Alembert (DALEMBERT), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Combustion, Energies Propres et Turbulence (IJLRDA-CEPT), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Shock wave, Water hammer, Work (thermodynamics), Yield (engineering), Materials science, Acoustics and Ultrasonics, Bubble, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Sonochemistry, Inorganic Chemistry, Chemical Engineering (miscellaneous), Environmental Chemistry, [CHIM]Chemical Sciences, Radiology, Nuclear Medicine and imaging, ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], Organic Chemistry, Mechanics, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Shock (mechanics), [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, 13. Climate action, Cavitation, 0210 nano-technology, [CHIM.RADIO]Chemical Sciences/Radiochemistry
Abstract

A strong impact on a water surface induces a shock wave propagation with a significant pressure variation leading to cavitation bubble formation. A new shock induced cavitation reactor described in this work was characterized by physical and chemical techniques. Water hammer model verification with Joukowsky approach allowed to determine the wave speed propagation and gas fraction in water submitted to shock. These values were used for frequency analysis and compared with direct bubble visualization in order to estimate the influence of the experimental parameters on the shock-induced cavitation. Thereby, the shock wave contains a broad spectrum as decomposed into frequencies. This multi-frequency nature induces heterogeneous bubbles with calculated radii of 0.01 to 3.5 mm and observed radii of 0.01 to 2.8 mm depending on experimental conditions (initial pressure, impact height, gas atmosphere). For the first time, the formation of hydroxyl radicals was proven under impact-induced cavitation. The concentration of radicals increases with increasing number of successive impacts, reaching ca. 1.3 µmol.L−1 after 500 impacts in the presence of 20% O2-Ar as saturating gas. Radical generation seems to be relatively independent of the impact height but strongly depend on the type of gas saturating water, being substantially lower in the presence of air. Moreover, radical generation increases when decreasing the initial pressure and depends on the frequency at which water is impacted by the piston. Nevertheless, yield of OH radicals during shock-induced cavitation remains much lower than that produced by power ultrasound.

Published
2020
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10. Acoustic noise spectra under hydrothermal conditions

Author

Rachel Pflieger, Sergey I. Nikitenko, Marianne Brau, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Acoustics and Ultrasonics, Bubble, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Molecular physics, Hydrothermal circulation, Spectral line, Physics::Fluid Dynamics, Inorganic Chemistry, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], business.industry, Organic Chemistry, Ultrasound, Atmospheric temperature range, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph], [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Cavitation, Particle, Ultrasonic sensor, 0210 nano-technology, business, [CHIM.RADIO]Chemical Sciences/Radiochemistry
Abstract

Acoustic noise spectra were studied for the first time in overheated water using sonohydrothermal reactor operating at 20 kHz ultrasound in the temperature range from 25 to 200 °C at the autogenic pressure of 1–14 bar. The obtained results highlighted a dominating role of stable cavitation during ultrasonic treatment of hot water. Heating of sonicated water results in the formation of large number of nonlinearly oscillating bubbles synchronous with the driving frequency. At 200 °C, the acoustic spectra also display strong subharmonic and multiple ultraharmonic bands. Moreover, cavitation bubbles formed at 200 °C exhibit chaotic and random motions. It has been shown that the addition of TiO2 nanoparticles to hydrothermal water heated at 200 °C allows to eliminate subharmonic/ultraharmonic bands and stochastic oscillations as well. This effect was assigned to Pickering-like bubble stabilization due to the particle accumulation at the bubble surface.

Published
2020
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11. Hierarchical Porosity Tailoring of Sol–Gel Derived Pt/SiO2 Catalysts

Author

Vasile Hulea, Siglinda Perathoner, Patrick Lacroix-Desmazes, Andrés Felipe Sierra-Salazar, Sergey I. Nikitenko, Tony Chave, André Ayral, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut Européen des membranes (IEM), Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Department of Industrial Chemistry and Engineering of Materials, University of Messina, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Materials science, Latex, 02 engineering and technology, Sol–gel, 010402 general chemistry, 01 natural sciences, Catalysis, Sonochemistry, Reaction rate, Hierarchical porosity, [CHIM]Chemical Sciences, p-Chloroaniline, Porosity, Sol-gel, General Chemistry, 021001 nanoscience & nanotechnology, Pt/SiO2, Selective hydrogenation, 0104 chemical sciences, Chemical engineering, p-Chloronitrobenzene, Porosity tailoring, 0210 nano-technology, Porous medium, Mesoporous material, Selectivity
Abstract

International audience; Hierarchically porous materials offer the opportunity for catalyst development in regards to improving catalytic performances. In the present work, the combination of latex synthesis, sonochemical reduction and two-step catalysed sol–gel process has been demonstrated to be a versatile method for preparing supported catalysts with tailored hierarchical porosity. This method has been used to prepare porous Pt/SiO2 catalysts with mesopore and macropore size ranges as large as 2–15 nm and 90–400 nm, respectively. These hierarchically porous catalysts presented an excellent catalytic performance for the selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). Selectivity values up to 100% at 80% conversion of p-CNB and initial reaction rates up to 74.0 molCNB/min molPt were obtained, while a commercial catalyst exhibited both a lower selectivity of 90.8% and a lower initial reaction rate of 47.7 molCNB/min molPt.

Published
2018
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12. Hierarchically porous Pd/SiO2 catalyst by combination of miniemulsion polymerisation and sol-gel method for the direct synthesis of H2O2

Author

Vasile Hulea, Andrés Felipe Sierra-Salazar, André Ayral, Salvatore Abate, Sergey I. Nikitenko, W.S. Jennifer Li, Patrick Lacroix-Desmazes, Tony Chave, Maël Bathfield, Siglinda Perathoner, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Institut Européen des membranes (IEM), Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM), Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Industrial Chemistry and Engineering of Materials, University of Messina, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Hydrogen, H2O2, chemistry.chemical_element, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, Pd/SiO2, 01 natural sciences, Catalysis, Hierarchical porosity, chemistry.chemical_compound, Polymer chemistry, [CHIM]Chemical Sciences, Hydrogen peroxide, Porosity, ComputingMilieux_MISCELLANEOUS, Sol-gel, Chemistry (all), [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry, General Chemistry, Miniemulsion polymerisation, 021001 nanoscience & nanotechnology, H2O2, Hierarchical porosity, Miniemulsion polymerisation, Pd/SiO2, Sol-gel, Catalysis, Chemistry (all), 0104 chemical sciences, Miniemulsion, [CHIM.POLY]Chemical Sciences/Polymers, Chemical engineering, chemistry, Polymerization, 0210 nano-technology, Selectivity
Abstract

The production of hydrogen peroxide H 2 O 2 , as an important commodity chemical, attires the attention towards greener processes such as the direct synthesis from hydrogen H 2 and oxygen O 2 , the selectivity being the biggest challenge. Since this reaction is structure-sensitive, the design of appropriate catalysts is required. We propose a novel method to prepare hierarchically porous Pd/SiO 2 catalyst by combination of miniemulsion polymerisation to prepare a Pd-containing latex template and sol-gel synthesis in controlled conditions to tailor the silica porosity. The final material displayed a surface area of 711 m 2 g −1 and a total pore volume of 0.93 cm 3 g −1 . The catalyst was evaluated with different pre-treatments in the direct synthesis of H 2 O 2 , where it exhibited structural resistance at the reaction conditions and a stable selectivity of 46 ± 1% towards H 2 O 2 .

Published
2018
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13. Hypothesis about electron quantum tunneling during sonochemical splitting of water molecule

Author

R. Pflieger, Sergey I. Nikitenko, Timothé Di Pasquale, Tony Chave, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Acoustics and Ultrasonics, Hydrogen, chemistry.chemical_element, 02 engineering and technology, Electron, 010402 general chemistry, 01 natural sciences, 7. Clean energy, water splitting, Dissociation (chemistry), Sonochemistry, Inorganic Chemistry, Sonoluminescence, kinetic isotope effect, Kinetic isotope effect, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, Quantum tunnelling, plasma, Organic Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry, Chemical physics, 0210 nano-technology, sonochemistry, quantum tunneling, Self-ionization of water
Abstract

International audience; Quantum tunneling in chemistry is often attributed to the processes at low or near room temperatures when the rate of thermal reactions becomes far less than the rate of quantum tunneling. However, in some rapid processes, quantum tunneling can be observed even at high temperatures. Herein, we report the experimental evidence for anomalous H/D kinetic isotope effect (KIE) during sonochemical dissociation of water molecule driven by 20 kHz power ultrasound measured in H 2 O/D 2 O mixtures saturated with Ar or Xe. Hydrogen released during ultrasonic treatment is enriched by light isotope. The observed H/D KIE (α=2.15-1.50) is much larger than what is calculated assuming a classical KIE for T g =5000 K (α=1.15) obtained from the sonoluminescence spectra in H 2 O and D 2 O. Furthermore, the α values sharply decrease with increasing of H 2 O content in H 2 O/D 2 O mixtures reaching a steady-state value close to α=1.50, which also cannot be explained by O-H/O-D zero-point energy difference. We suggest that these results can be understood in terms of quantum electron tunneling occurring in nonequilibrium picosecond plasma produced at the last stage of cavitation bubble collapse. Thermal homolytic splitting of water molecule is inhibited by extremely short lifetime of such plasma. On the contrary, immensely short traversal time for electron tunneling in water allows H 2 O dissociation by quantum tunneling mechanism.

Published
2020
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14. Effect of NaCl salt on sonochemistry and sonoluminescence in aqueous solutions

Author

Rachel Pflieger, Sergey I. Nikitenko, Muthupandian Ashokkumar, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), School of Chemistry [Melbourne], Faculty of Science [Melbourne], University of Melbourne-University of Melbourne, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Acoustics and Ultrasonics, Hydrogen, Inorganic chemistry, Salt (chemistry), chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Chemical reaction, Sonochemistry, Inorganic Chemistry, chemistry.chemical_compound, Sonoluminescence, Chemical Engineering (miscellaneous), Environmental Chemistry, [CHIM]Chemical Sciences, Radiology, Nuclear Medicine and imaging, Solubility, Hydrogen peroxide, chemistry.chemical_classification, Aqueous solution, Organic Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, 13. Climate action, 0210 nano-technology
Abstract

International audience; The presence of salts in a solution is known to affect sonochemistry, but until now no consensus has been reached in the literature on how and why a salt influences sonochemistry. The present study focuses on the effect of NaCl on sonochemical activity and sonoluminescence at 362-kHz frequency in aqueous solutions saturated with He and Ar. It is shown that the presence of salt has a multiple impact: the global population of active bubbles decreases due to the decreasing gas solubility, new chemical reactions involving Na and Cl atoms occur that influence hydrogen and hydrogen peroxide yields and the standing wave component of the US wave is enhanced, favoring sonoluminescence emission. Interestingly, the effect of salt greatly depends on the nature of the saturating gas: for instance, strong acidification occurs under He, while it is limited under Ar.

Published
2019
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15. Molecular emissions in sonoluminescence spectra of water sonicated under Ar- based gas mixtures

Author

Rachel Pflieger, Cédric Noël, Sergey I. Nikitenko, Thierry Belmonte, E. Fayard, Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Sonochimie dans les Fluides Complexes (LSFC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Acoustics and Ultrasonics, Analytical chemistry, 02 engineering and technology, 010402 general chemistry, 7. Clean energy, 01 natural sciences, Spectral line, Sonochemistry, Inorganic Chemistry, symbols.namesake, Sonoluminescence, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, Emission spectrum, Spectroscopy, [SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph], Aqueous solution, Organic Chemistry, [SPI.PLASMA]Engineering Sciences [physics]/Plasmas, Plasma, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Stark effect, symbols, 0210 nano-technology
Abstract

International audience; Sonoluminescence (SL) spectroscopy is one of the very few ways to study the plasma formed in solutions submitted to ultrasound. Unfortunately, up to now only very limited emission bands were reported in SL spectra of aqueous solutions, moreover broad and badly resolved. It is shown here that by adding some N2 and/or CO2 in Ar, new molecular emissions (CN, N2 and CO) can be observed and that for some of them rovibronic temperatures can be derived. The paramount importance of Stark broadening in these emissions is underlined, together with the need for data on Stark parameters for molecular emissions.

Published
2019
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16. Use of NH (A3Π–X3Σ−) sonoluminescence for diagnostics of nonequilibrium plasma produced by multibubble cavitation

Author

Sergey I. Nikitenko, R. Pflieger, Temim Ouerhani, Thierry Belmonte, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Thermal equilibrium, Chemistry, Analytical chemistry, General Physics and Astronomy, 02 engineering and technology, Plasma, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Spectral line, 0104 chemical sciences, Sonochemistry, Sonoluminescence, 13. Climate action, Cavitation, Electron temperature, Physical and Theoretical Chemistry, Atomic physics, [CHIM.OTHE]Chemical Sciences/Other, 0210 nano-technology, Spectroscopy
Abstract

International audience; In this work, the sonoluminescence of NH radicals has been evaluated as a new spectroscopic probe for the nonequilibrium plasma produced by multibubble cavitation in liquids. The experiments were performed in aqueous ammonia solutions subjected to power ultrasound at low and high frequencies and under two different rare gases (Ar and Xe). Sonoluminescence (SL) spectroscopy focuses on the emission of the two present systems: NH (A 3 P-X 3 S À) and OH (A 2 S +-X 2 P). Both spectroscopic systems indicate the absence of thermal equilibrium during bubble collapse (T v 4 T r) irrespective of the saturating gas. When Ar is used as the saturating gas, these emissions can be fitted using Specair software and the corresponding rovibronic temperatures are derived. Both species indicate a net increase in vibrational temperatures with the US frequency. In Xe, the SL spectra exhibit OH (C 2 S +-A 2 S +) and NH (c 1 P-a 1 D) emission bands indicating a higher electron temperature compared to Ar. However, in Xe, the SL spectra cannot be satisfactorily fitted because of significant line broadening. The estimation of the intrabubble pressure via SL simulation using Specair software is discussed. Monitoring of the sonochemical activity indicates the formation of H 2 and N 2 H 4 , while no H 2 O 2 accumulates under these conditions. In the presence of Xe, NO is also formed as a sonolysis product. The appearance of new possible reaction pathways under Xe is made possible by the higher plasma electron density and correlates with SL data.

Published
2017
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17. Unconventional Pathways for Designing Silica-Supported Pt and Pd Catalysts With Hierarchical Porosity

Author

Vasile Hulea, Tony Chave, Andrés Felipe Sierra-Salazar, Salvatore Abate, Sergey I. Nikitenko, Siglinda Perathoner, Patrick Lacroix-Desmazes, André Ayral, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Department of Industrial Chemistry and Engineering of Materials, University of Messina, Institut Européen des membranes (IEM), Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM), Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Green chemistry, Chemical process, Materials science, Software_GENERAL, Rational design, Pillar, Nanotechnology, 02 engineering and technology, [CHIM.CATA]Chemical Sciences/Catalysis, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Environmentally friendly, 0104 chemical sciences, Catalysis, [CHIM.POLY]Chemical Sciences/Polymers, 0210 nano-technology, Porosity, Hierarchical porous, ComputingMilieux_MISCELLANEOUS
Abstract

Catalysis as a pillar of green chemistry is called on to improve the performance of the current chemical processes and to develop new and sustainable processes and products. In order to tackle the current challenges in sustainable chemistry, catalyst rational design approaches are necessary. Such approaches require tailoring tools for the catalyst preparation, which should also be environmentally friendly. This chapter starts by a brief review of the techniques for texture tailoring and catalyst functionalization, highlighting the high potential of hierarchical porous catalysts. Then, a few innovative techniques for the preparation of silica-supported Pt and Pd catalysts with hierarchical porosity are described.

Published
2019
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18. Diagnosing the plasma formed during acoustic cavitation in [BEPip][NTf2] ionic liquid

Author

Micheline Draye, Thierry Belmonte, Sergey I. Nikitenko, Manuel Lejeune, Rachel Pflieger, Cédric Noël, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire LCME / Equipe Chimie Verte (LCME_CV), Laboratoire de Chimie Moléculaire et Environnement (LCME), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph], [PHYS]Physics [physics], Materials science, Sonication, [SPI.PLASMA]Engineering Sciences [physics]/Plasmas, Analytical chemistry, General Physics and Astronomy, 02 engineering and technology, Plasma, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Spectral line, 0104 chemical sciences, Sonochemistry, chemistry.chemical_compound, Sonoluminescence, chemistry, Cavitation, Excited state, Ionic liquid, Physical and Theoretical Chemistry, 0210 nano-technology
Abstract

International audience; Sonoluminescence (SL) spectra of a very dry [BEPip][NTf 2 ] ionic liquid were measured in the first minutes of sonication under Ar. The intense sonoluminescence allowed us to monitor the time-evolution of the SL spectra. Several molecular emissions were observed. Rovibronic temperatures of C 2 and CN were determined giving vibrational temperatures of 5800 AE 500 K and 6000 AE 500 K and rotational temperatures (i.e. translational or gas temperatures) of 4000 AE 500 K. These temperatures stay remarkably constant during the sonolysis, while SL spectra undergo strong changes that illustrate the very fast evolution of the plasma during the first minutes of sonication. The expected strong decrease in the plasma electron energy also reflects in the evolution of the populations of CH electronically excited states. The physical meaning of temperatures derived from molecular emissions in SL spectra is discussed.

Published
2019
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19. Probing the Local Structure of Nanoscaled Actinide Oxides: A Comparison between PuO2 and ThO2 Nanoparticles Rules out PuO2+x Hypothesis

Author

Thierry Wiss, Laurent Venault, Philippe Moisy, Thomas Dumas, Adel Mesbah, Oliver Dieste Blanco, Matthieu Virot, Damien Prieur, Laura Bonato, Xavier F. Le Goff, Sergey I. Nikitenko, Elodie Dalodière, Michael Odorico, Nicolas Dacheux, André Rossberg, CEA, Contributeur MAP, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Northwestern University [Evanston], European Commission - Joint Research Centre [Karlsruhe] (JRC), Etude de la Matière en Mode Environnemental (L2ME), European Synchrotron Radiation Facility (ESRF), Département RadioChimie et Procédés (DRCP), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Interfaces de Matériaux en Evolution (LIME), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Institut des Sciences et technologies pour une Economie Circulaire des énergies bas carbone (ISEC)

Subjects
[CHIM.INOR] Chemical Sciences/Inorganic chemistry, Materials science, Oxide, Nanoparticle, Bioengineering, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Colloid, chemistry.chemical_compound, [CHIM.RADIO] Chemical Sciences/Radiochemistry, [CHIM.CRIS]Chemical Sciences/Cristallography, General Materials Science, Reactivity (chemistry), [CHIM.CRIS] Chemical Sciences/Cristallography, ComputingMilieux_MISCELLANEOUS, [CHIM.MATE] Chemical Sciences/Material chemistry, Extended X-ray absorption fine structure, General Engineering, [CHIM.MATE]Chemical Sciences/Material chemistry, General Chemistry, Actinide, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Characterization (materials science), Nanocrystal, chemistry, Chemical physics, 0210 nano-technology, [CHIM.RADIO]Chemical Sciences/Radiochemistry
Abstract

International audience; Actinide research at the nanoscale is gaining fundamental interest due to environmental and industrial issues. The knowledge of the local structure and speciation of actinide nanoparticles, which possibly exhibit specific physico-chemical properties in comparison to bulk materials, would help in a better and reliable description of their behaviour and reactivity. Herein, the synthesis and relevant characterization of PuO2 and ThO2 nanoparticles displayed as dispersed colloids, nanopowders or nanostructured oxide powders, allow to establish a clear relationship between the size of the nanocrystals composing these oxides and their corresponding An(IV) local structure investigated by EXAFS spectroscopy. Particularly, the probed An(IV) first oxygen shell evidences an analogous behaviour for both Pu and Th oxides. This observation suggests that the often observed and controversial splitting of the Pu-O shell on the Fourier transformed EXAFS signal of PuO2 samples is attributed to a local structural disorder driven by a nanoparticle surface effect rather than to the presence of PuO2+x species.

Published
2019
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20. Sonocatalytic oxidation of EDTA in aqueous solutions over noble metal-free Co$_3$O$_4$/TiO$_2$ catalyst

Author

Hugo Dutilleul, Laureanne Parizot, Patrick Da Costa, Tony Chave, M. E. Gálvez, Sergey I. Nikitenko, Institut Jean Le Rond d'Alembert (DALEMBERT), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Iminodiacetic acid, Formic acid, Oxalic acid, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, Catalysis, chemistry.chemical_compound, Acetic acid, Ultrasound, Glycolic acid, General Environmental Science, Heterogeneous catalysis, Aqueous solution, [SDE.IE]Environmental Sciences/Environmental Engineering, Process Chemistry and Technology, technology, industry, and agriculture, EDTA, Advanced oxidation processes, [CHIM.CATA]Chemical Sciences/Catalysis, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, engineering, Noble metal, 0210 nano-technology, Nuclear chemistry, Sonochemistry
Abstract

International audience; The sonocatalytic degradation of EDTA in aqueous solution was studied under ultrasound irradiation (345 kHz, 73 W, acoustic power 0.20 W·mL$^{−1}$, Ar and Ar/O$_2$ saturating gases, T = 20–50 °C) in the presence of Co$_3$3O$_4$/TiO$_2$ and Pt/TiO$_2$ nanocatalysts. About 90% of EDTA (C$_0$ = 5 10$^{-3}$ M) was oxidized during ultrasonic treatment at 40 °C in the presence of the Co$_3$O$_4$/TiO$_2$ catalyst and Ar/O$_2$ gas mixture. By contrast, Pt/TiO$_2$ catalyst exhibited much lower sonocatalytic activity in this system. Suggested mechanism of EDTA oxidation in the presence of Co$_3$O$_4$/TiO$_2$ catalyst involved the generation of oxidizing radicals by acoustic cavitation and Co(II)-Co(III) redox process. Quite low apparent activation energy of the sonocatalytic process (E$_a$ = 19 kJ mol$^{−1}$) was attributed to diffusion of reagents in the vicinity of the active sites of catalyst. Sonocatalytic degradation of EDTA is accompanied by formation of iminodiacetic acid, formic acid, oxalic acid, glycolic acid and acetic acid as intermediate products in an agreement with radical-driven mechanism.

Published
2019
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21. Insights into the Photothermal Hydrogen Production from Glycerol Aqueous Solutions over Noble Metal-Free Ti@TiO 2 Core-Shell Nanoparticles

Author

Tony Chave, Xavier Le Goff, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Etude de la Matière en Mode Environnemental (L2ME), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Hydrogen, Nanoparticle, chemistry.chemical_element, 02 engineering and technology, engineering.material, 010402 general chemistry, Photochemistry, 01 natural sciences, 7. Clean energy, Catalysis, General Materials Science, Hydrogen production, Aqueous solution, Photothermal effect, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, chemistry, 13. Climate action, engineering, Photocatalysis, Noble metal, 0210 nano-technology
Abstract

International audience; Photocatalytic production of hydrogen from renewable sources with platinum group metal‐free catalysts is of great importance for environmentally friendly energetics. Herein, Ti@TiO2 core–shell nanoparticles prepared by sonohydrothermal treatment of titanium metal nanoparticles are examined for hydrogen generation from aqueous glycerol solutions under vis/NIR light irradiation. It is shown that photocatalytic reforming of glycerol in the presence of Ti@TiO2 exhibits strong photothermal effect allowing more efficient use of solar energy. Apparent activation energy equal to E act = 27 ± 2 kJ mol−1 indicates that the thermal effect is related to the diffusion of reaction intermediates at catalyst surface rather than to the activation of chemical bonds. The photoexcitation mechanism of Ti@TiO2 particles involves interband transitions in nonplasmonic Ti metal core followed by nonradiative Landau damping. Effective electron–hole separation between Ti core and nanocrystalline TiO2 anatase shell in Ti@TiO2 nanoparticles is confirmed by photoluminescence spectroscopy. In studied system, photothermal hydrogen production is not accompanied by CO2 emission indicating that glycerol is oxidized to glyceric acid without further decarboxylation.

Published
2018
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22. Inverse effects of the gas feed positioning on sonochemistry and sonoluminescence

Author

Rachel Pflieger, Gilles Guillot, Muthupandian Ashokkumar, Sergey I. Nikitenko, Léa Gravier, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), University of Melbourne, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Acoustics and Ultrasonics, Flow (psychology), 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Sonochemistry, Inorganic Chemistry, Sonoluminescence, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, Solubility, Spectroscopy, ComputingMilieux_MISCELLANEOUS, geography, Aqueous solution, geography.geographical_feature_category, Organic Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Inlet, 0104 chemical sciences, Chemical physics, 0210 nano-technology, Intensity (heat transfer)
Abstract

Purging of solutions to enhance sonochemical reactions is a common practice. A fundamental study combining sonoluminescence spectroscopy and sonochemical activity is adopted to study the effects of continuous Ar gas flow in the solution and of the position of the gas inlet tube on high-frequency sonolysis of aqueous solutions. It has been observed that neither sonochemical activity nor sonoluminescence intensity is controlled by the gas solubility only. Besides, the change in position of the gas inlet tube leads to opposite effects in sonoluminescence intensity and sonochemical activity: while the former increases, the latter decreases. Such an observation has never been reported despite sonochemical reactions have been carried out under different gas environments. Sonoluminescence spectroscopy indicates that more extreme conditions are reached at collapse with the gas inlet on the side, which could be explained by a more symmetrical collapse. Finally, it is shown in certain conditions that it is possible to favor the formation of some sonochemical products simply by positioning the gas inlet at different positions, which has practical significance in designing large scale sonochemical reactors for industrial applications.

Published
2018
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23. Multibubble Sonochemistry and Sonoluminescence at 100 kHz: The Missing Link between Low- and High-Frequency Ultrasound

Author

Rachel Pflieger, Matthieu Virot, Sergey I. Nikitenko, R. Ji, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Yield (engineering), business.industry, Sonication, Acoustics, Ultrasound, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Spectral line, 0104 chemical sciences, Surfaces, Coatings and Films, Sonochemistry, Sonoluminescence, Cavitation, Materials Chemistry, Ultrasonic sensor, Physical and Theoretical Chemistry, 0210 nano-technology, business, ComputingMilieux_MISCELLANEOUS
Abstract

Ultrasonic frequency is one of the most important parameters that decides the characteristics of acoustic cavitation. Low- (16–50 kHz) and high- (≥200 kHz) frequency ultrasounds present opposite physical and chemical behaviors and have been extensively studied, yet frequencies in between are poorly characterized. In this study, acoustic cavitation at the intermediate ultrasonic frequency of 100 kHz is compared with that at 20 kHz and at 362 kHz by different experimental investigations: sonochemical yield (H2O2), images of sonochemiluminescence and sonoluminescence, as well as sonoluminescence spectra in aqueous media saturated with Ar or Ar/(20 vol %)O2. The chemical activity (H2O2 yield) of cavitation bubbles at 100 kHz presents a transitional behavior between low and high frequencies. The active cavitation zone distributes in the whole sonicated volume, similarly to high-frequency ultrasound and much further than at 20 kHz. The spectral shape of 100 kHz spectra is similar to that at 20 kHz. On the contr...

Published
2018
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24. Ultrasound-assisted reductive dissolution of CeO2and PuO2in the presence of Ti particles

Author

Sergey I. Nikitenko, Tony Chave, Laurent Venault, Gilles Leturcq, Gauthier Jouan, Philippe Moisy, Xavier Beaudoux, Matthieu Virot, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Sonication, Inorganic chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 7. Clean energy, 01 natural sciences, Redox, 0104 chemical sciences, Corrosion, Inorganic Chemistry, chemistry.chemical_compound, Hydrofluoric acid, chemistry, Nitric acid, Reagent, 0210 nano-technology, Fluoride, Dissolution, ComputingMilieux_MISCELLANEOUS
Abstract

PuO2 is considered an important material for current and future nuclear fuel; however it is a very refractive compound towards dissolution. Among other techniques, its reprocessing can be performed via complexing dissolution in concentrated and boiling nitric acid containing hydrofluoric acid, or via oxidant dissolution in the presence of reagents with redox couples having high potentials such as Ce(iv)/Ce(iii), or Ag(ii)/Ag(i). Reductive dissolution can be performed under softer conditions and is considered an alternative to these methods which may suffer from several drawbacks (corrosion, effluent management, compatibility with nuclear waste disposal, etc.). In this study, a sonochemical and reductive approach is investigated for PuO2 dissolution under relatively mild conditions. At the first stage, the experiments are performed with CeO2 as an inactive surrogate for PuO2. The quantitative dissolution of both oxides can be achieved under ultrasound (20 kHz, 0.35-0.70 W mL(-1)) in 0.5 M HNO3/0.1 M [N2H5NO3]/2 M HCOOH sparged with Ar at 33-35 °C in the presence of Ti particles as a generating source of reductive species. Ultrasound enables the depassivation of the Ti surface (usually strongly passivated in nitric solutions) through acoustic cavitation which then allows further generation of the intermediate Ti(iii) reductive species. Dissolution rates and yields can be further increased with the injection of dilute fluoride aliquots (NH4F or HF) in the sonicated solution to favor Ti chemical depassivation. The rapid and complete dissolution of PuO2 under selected conditions is accompanied by Pu(iii) accumulation in solution.

Published
2016
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25. Structural and magnetic susceptibility characterization of Pu(V) aqua ion using sonochemistry as a facile synthesis method

Author

Thomas Dumas, Marie-Claire Illy, Claude Berthon, Laurent Venault, André Rossberg, Philippe Moisy, Matthieu Virot, Laetitia Guerin, Sergey I. Nikitenko, Elodie Dalodière, Dominique Guillaumont, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), European Synchrotron Radiation Facility (ESRF), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Aqueous solution, Absorption spectroscopy, Extended X-ray absorption fine structure, Chemistry, Disproportionation, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetic susceptibility, 0104 chemical sciences, X-ray absorption fine structure, Sonochemistry, Inorganic Chemistry, Physical chemistry, Curie constant, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Nuclear chemistry
Abstract

Since the past few years, Pu(V) has gained much attention due to its potential contribution to the environmental migration of actinides. However, the preparation of concentrated (up to mM) and pure Pu(V) solutions is quite difficult and often hindered by its great instability towards disproportionation, thus limiting the accessibility to physical and chemical property data. This work describes the rapid and facile sonochemical preparation of relatively stable Pu(V) solutions in the millimolar range free from the admixtures of the other oxidation states of plutonium. The mechanism deals with the sonochemical reduction of Pu(VI) in weakly acidic perchloric solutions by using the in situ generated H2O2, where the kinetics can be dramatically enhanced under high frequency ultrasound and an Ar/O2 atmosphere. The quasi-exclusive presence of the Pu(V) aqua ion in solution was evidenced by UV-vis absorption spectroscopy. The prepared solutions were found to be stable for more than one month which allowed the accurate XAFS and NMR investigations of Pu(V). EXAFS spectra revealed the presence of two trans dioxo Pu[double bond, length as m-dash]O bonds at 1.81 Å and 4–6 equatorial Pu–Oeq interactions at 2.47 Å characteristic of coordinated water molecules. The exact number of water molecules (N[Oeq(H2O)] = 4) was determined by simulating the EXAFS spectra of the PuO2+ aqua complexes using DFT calculations (geometry and the Debye–Waller factor) and comparing them with experimental signals. For the first time, the magnetic susceptibility of the pentavalent state of plutonium in aqueous solutions was also determined (χM = 16.3 × 10−9 m3 mol−1 at 25 °C) and the related Curie constant was estimated (C = 6.896 × 10−6 m3 K mol−1).

Published
2018
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26. Controlled 'golf ball shape' structuring of Mg surface under acoustic cavitation

Author

Xavier F. Le Goff, Ran Ji, Sergey I. Nikitenko, R. Pflieger, Renaud Podor, Matthieu Virot, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Etude de la Matière en Mode Environnemental (L2ME), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Acoustics and Ultrasonics, Sonication, Organic Chemistry, Nanotechnology, 02 engineering and technology, Surface finish, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, 0104 chemical sciences, Inorganic Chemistry, Cavitation, Nano, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, Ultrasonic sensor, Wetting, Composite material, 0210 nano-technology, Dissolution, ComputingMilieux_MISCELLANEOUS
Abstract

This manuscript describes the original structuring of Mg materials under ultrasound irradiation in mild conditions. Golf ball like extended structures can be prepared in dilute oxalic solutions at 20 °C under high frequency ultrasound (200 kHz). An original approach carried out through iterative 3D reconstruction of sonicated surfaces is used to describe surface evolutions and characterize the formed microstructures. A combination of SEM, ICP-AES, contact-angle measurements, and 3D image analyses allows to characterize the roughness and mass loss evolutions, and investigate the mechanism of formation for such architectures. A screening of the sonication experiments clearly points out an ultrasound frequency dependency for the effects generated at the surface. 200 kHz sonication in 0.01 M oxalic acid provides an unprecedented manufacturing of Mg samples which result from a controlled and localized dissolution of the material and characterized by a strong wetting surface with a roughness of 170 nm. The additional formation of newly formed secondary phases appearing with surface dissolution progress is also deciphered. More generally, the ultrasonic procedure used to prepare these engineered surfaces opens new alternatives for the nano- and micro-structuring of metallic materials which may exhibit advanced physical and chemical properties of potential interest for a large community.

Published
2018
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27. Insights into the sonochemical synthesis and properties of salt-free intrinsic plutonium colloids

Author

David K. Shuh, Philippe Moisy, Oliver Dieste Blanco, Vincent Morosini, Thomas Dumas, Laurent Venault, Tony Chave, Christoph Hennig, Sergey I. Nikitenko, Elodie Dalodière, Matthieu Virot, Thierry Wiss, Tolek Tyliszcak, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Analyse, Géométrie et Modélisation (AGM - UMR 8088), Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), European Synchrotron Radiation Facility (ESRF), European Commission - Joint Research Centre [Karlsruhe] (JRC), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Advanced Light Source [LBNL Berkeley] (ALS), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), European Project: 323300,EC:FP7:Fission,FP7-Fission-2012,TALISMAN(2013), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
X-ray absorption spectroscopy, Multidisciplinary, digestive, oral, and skin physiology, Kinetics, chemistry.chemical_element, Nanoparticle, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Pu(IV) colloids, 01 natural sciences, Article, XANES, 0104 chemical sciences, Plutonium, Other Physical Sciences, Colloid, chemistry, Chemical engineering, Water splitting, Biochemistry and Cell Biology, sonochemistry, 0210 nano-technology, High-resolution transmission electron microscopy
Abstract

For the first time, stable intrinsic plutonium colloid was prepared by ultrasonic treatment of PuO2 suspensions in pure water at room temperature. The yield of Pu colloid was found to increase with PuO2 specific surface area and by using reducing carrier gas mixture. Kinetic data evidenced that both chemical and mechanical effects of ultrasound strongly contribute to the mechanism of Pu colloid formation. At first, the fragmentation of initial PuO2 particles accelerates the overall process providing larger surface of contact between cavitation bubbles and solids. Furthermore, hydrogen formed during sonochemical water splitting enables reduction of Pu(IV) to more soluble Pu(III), which then reoxidizes yielding Pu(IV) colloid. Sonochemical colloid was compared with hydrolytic one using HRTEM, Pu LIII XAS, and STXM/NEXAFS (O K-edge) techniques. Both colloids are composed of quasi-spherical nanocrystalline particles of PuO2 (fcc, Fm¯3 m space group) measuring about 7 nm and 3 nm, respectively. Moreover, HRTEM revealed nanostructured morphology for initial PuO2. The EXAFS spectra of colloidal PuO2 nanoparticles were fitted using triple oxygen shell model for the first coordination sphere of Pu(IV). HRTEM and EXAFS studies revealed the correlation between the number of Pu-O and Pu-Pu contacts and atomic surface-to-volume ratio of studied PuO2 nanoparticles. The STXM/NEXAFS study indicated that the oxygen state of hydrolytic Pu colloid is influenced by hydrolyzed Pu(IV) species in much more extent than PuO2 nanoparticles of sonochemical colloid. In general, hydrolytic and sonochemical colloids can be described as core-shell nanoparticles composed of quasi stoichiometric PuO2 core and hydrolyzed Pu(IV) moieties at the surface shell.

Published
2017
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28. Thermal and sonochemical synthesis of porous (Ce,Zr)O2 mixed oxides from metal β-diketonate precursors and their catalytic activity in wet air oxidation process of formic acid

Author

Joulia Larionova, Sergey I. Nikitenko, Camille Cau, Tony Chave, Yannick Guari, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Acoustics and Ultrasonics, Inorganic chemistry, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, Platinum nanoparticles, 01 natural sciences, Catalysis, Inorganic Chemistry, Metal, chemistry.chemical_compound, Oleylamine, Specific surface area, Chemical Engineering (miscellaneous), Environmental Chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Radiology, Nuclear Medicine and imaging, Wet oxidation, Dissolution, ComputingMilieux_MISCELLANEOUS, Organic Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, visual_art, visual_art.visual_art_medium, 0210 nano-technology, Platinum
Abstract

Porous (Ce 0.5 Zr 0.5 )O 2 solid solutions were prepared by thermolysis ( T = 285 °C) or sonolysis (20 kHz, I = 32 W cm −2 , P ac = 0.46 W mL −1 , T = 200 °C) of Ce(III) and Zr(IV) acetylacetonates in oleylamine or hexadecylamine under argon followed by heat treatment of the precipitates obtained in air at 450 °C. Transmission Electron Microscopy images of the samples show nanoparticles of ca. 4–6 nm for the two synthetic approaches. The powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and μ-Raman spectroscopy of solids obtained after heat treatment indicate the formation of (Ce 0.5 Zr 0.5 )O 2 solid solutions with a metastable tetragonal crystal structure for the two synthetic routes. The specific surface area of the samples varies between 78 and 149 m 2 g −1 depending on synthesis conditions. The use of Barrett–Joyner–Halenda and t -plot methods reveal the formation of mixed oxides with a hybrid morphology that combines mesoporosity and microporosity regardless of the method of preparation. Platinum nanoparticles were deposited on the surface of the mixed oxides by sonochemical reduction of Pt(IV). It was found that the materials prepared by sonochemistry exhibit better resistance to dissolution during the deposition process of platinum. X-ray photoelectron spectroscopy analysis shows the presence of Pt(0) and Pt(II) on the surface of mixed oxides. Porous (Ce 0.5 Zr 0.5 )O 2 mixed oxides loaded with 1.5 %wt. platinum exhibit high activity in catalytic wet air oxidation of formic acid at 40 °C.

Published
2014
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29. Multibubble sonoluminescence as a tool to study the mechanism of formic acid sonolysis

Author

Rachel Pflieger, Nathalie M. Navarro, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Aqueous solution, Argon, Acoustics and Ultrasonics, Chemistry, Formic acid, Organic Chemistry, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, 01 natural sciences, Spectral line, 0104 chemical sciences, Sonochemistry, Inorganic Chemistry, chemistry.chemical_compound, Sonoluminescence, Carbon dioxide, [CHIM]Chemical Sciences, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, 0210 nano-technology
Abstract

International audience; Sonoluminescence spectra collected from 0.1 to 3.0 M aqueous solutions of formic acid sparged with argon show the OH(A2Σ+−X2Πi) and C2(d3Πg → a3Πu) emission bands and a broad continuum typical for multibubble sonoluminescence. The overall intensity of sonoluminescence and the sonochemical yield of HCOOH degradation vary in opposite directions: the sonoluminescence is quenched while the sonochemical yield increases with HCOOH concentration. By contrast, the concentration of formic acid has a relatively small effect on the intensity of C2 Swan band. It is concluded that C2 emission originates from CO produced by HCOOH degradation rather than from direct sonochemical degradation of HCOOH. The intensity of C2 band is much stronger at high ultrasonic frequency compared to 20 kHz ultrasound which is in line with higher yields of CO at high frequency. Another product of HCOOH sonolysis, carbon dioxide, strongly quenches sonoluminescence, most probably via collisional non-radiative mechanism.

Published
2014
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30. Sonochemical deposition of platinum nanoparticles on polymer beads and their transfer on the pore surface of a silica matrix

Author

Patrick Lacroix-Desmazes, Anthony Grunenwald, Sergey I. Nikitenko, Tony Chave, André Ayral, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut Européen des membranes (IEM), Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)

Subjects
Materials science, Formic acid, chemistry.chemical_element, Nanotechnology, 02 engineering and technology, 010402 general chemistry, Platinum nanoparticles, 01 natural sciences, Sonochemistry, Biomaterials, chemistry.chemical_compound, Colloid and Surface Chemistry, Deposition (phase transition), Porosity, ComputingMilieux_MISCELLANEOUS, chemistry.chemical_classification, Polymer, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, Chemical engineering, Polystyrene, 0210 nano-technology, Platinum
Abstract

This study reported the sonochemical deposition of platinum on the surface of polystyrene beads (PSBs) and the transfer of obtained Pt nanoparticles into a porous silica matrix using the PSB as a sacrificial template. Platinum nanoparticle deposition was ensured by the sonochemical reduction of Pt(IV) at room temperature in latex solutions containing polystyrene beads in the presence of formic acid under Ar or under Ar/CO atmosphere without any additives. After ultrasonic treatments for few hours, well dispersed Pt nanoparticles within the range of 3-5 nm deposited on PSB were obtained in both studied conditions. Samples were then mixed with TEOS, dried, and heated at 450°C to ensure the PSB removal from the silica matrix. TEM and SEM results clearly show that final silica pore size is within the same order of magnitude than initial PSB. Finally, platinum decorated silica matrix with chosen pore sizes was successfully prepared.

Published
2013
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31. The Origin of Isotope Effects in Sonoluminescence Spectra of Heavy and Light Water

Author

Abdoul Aziz Ndiaye, Bertrand Siboulet, Sergey I. Nikitenko, Rachel Pflieger, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Modélisation Mésoscopique et Chimie Théorique (LMCT), ANR-10-BLAN-0810,NEQSON,Sonochimie en condition hors équilibre(2010), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Bubble, Physics::Medical Physics, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Catalysis, Spectral line, Physics::Fluid Dynamics, isotope effects, chemistry.chemical_compound, Sonoluminescence, Nuclear magnetic resonance, cavitation, Physics::Plasma Physics, non‐equilibrium plasma, Kinetic isotope effect, [CHIM]Chemical Sciences, Heavy water, hydroxyl radicals, ultrasound, Chemistry, business.industry, Ultrasound, General Chemistry, Plasma, General Medicine, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Cavitation, Physics::Space Physics, Atomic physics, sonoluminescence, business, 0210 nano-technology
Abstract

International audience; The isotope effects in the sonoluminescence spectra of light and heavy water under ultrasound indicate the formation of a non‐equilibrium plasma inside the collapsing cavitation bubbles. The picture demonstrates the active cavitation zones in water at 204 kHz.

Published
2013
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32. Real time observation of X-ray-induced surface modification using simultaneous XANES and XEOL-XANES

Author

Annemie Adriaens, Mark Dowsett, Paul D. Quinn, Sergey I. Nikitenko, Universiteit Gent = Ghent University [Belgium] (UGENT), DIAMOND Light source, European Synchrotron Radiation Facility (ESRF), and Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England

Subjects
Chemistry, 010401 analytical chemistry, Analytical chemistry, 02 engineering and technology, Microbeam, 021001 nanoscience & nanotechnology, 01 natural sciences, XANES, Article, 0104 chemical sciences, Analytical Chemistry, K-edge, Absorption edge, Surface modification, [CHIM]Chemical Sciences, 0210 nano-technology, Phosphorescence, Luminescence, Absorption (electromagnetic radiation)
Abstract

International audience; In experiments preliminary to the design of an X-ray-excited optical luminescence (XEOL)-based chemical mapping tool we have used X-ray micro (4.5 X 5.2 mu m) and macro (1 X 6 mm) beams with similar total fluxes to assess the effects of a high flux density beam of X-rays at energies close to an absorption edge on inorganic surfaces in air. The near surface composition of corroded cupreous alloys was analyzed using parallel X-ray and optical photoemission channels to collect X-ray absorption near-edge structure (XANES) data at the Cu K edge. The X-ray fluorescence channel is characteristic of the composition averages over several micrometers into the surface, whereas the optical channel is surface specific to about 200 nm. While the X-ray fluorescence data were mostly insensitive to the X-ray dose, the XEOL-XANES data from the rnicrobeam showed significant dose-dependent changes to the superficial region, including surface cleaning, changes in the oxidation state of the copper, and destruction of surface compounds responsible for pre-edge fluorescence or phosphorescence in the visible. In one case, there was evidence that the lead phase in a bronze had melted. Conversely, data from the macrobeam were stable over several hours. Apart from localized heating effects, the microbeam damage is probably associated with the O-3 loading of the surface and increased reaction rate with atmospheric water vapor

Published
2013
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33. Effect of ultrasonic frequency on H2O2 sonochemical formation rate in aqueous nitric acid solutions in the presence of oxygen

Author

Philippe Moisy, Sergey I. Nikitenko, Elodie Dalodière, Matthieu Virot, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Acoustics and Ultrasonics, Sonication, Analytical chemistry, chemistry.chemical_element, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Oxygen, Sonochemistry, Inorganic Chemistry, chemistry.chemical_compound, Nitric acid, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, Hydrogen peroxide, NOx, ComputingMilieux_MISCELLANEOUS, Nitrous acid, Aqueous solution, Organic Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, 13. Climate action, 0210 nano-technology
Abstract

The influence of the ultrasonic frequency (20 kHz, 207 kHz, and 615 kHz) towards the formation kinetics of H2O2 under Ar and Ar/(20 vol.%)O2 atmospheres was evaluated in pure water and aqueous nitric solutions. Results obtained at low frequency ultrasound demonstrate that hydrogen peroxide formation is enhanced under an Ar/O2 gas mixture whatever the sonicated medium. Nevertheless, H2O2 yields are higher in aqueous nitric solutions whatever the nature of the saturating gas. These observations are consistent at high frequency ultrasound under Ar gas notwithstanding higher yields for H2O2. Surprisingly, an inverse tendency is observed for high frequency sonolysis carried out under an Ar/O2 atmosphere: higher yields of H2O2 are measured in pure water. Further studies in the presence of pure Ar revealed a more important decomposition of nitric acid under high frequency ultrasound leading to higher yields of both HNO2 in the liquid phase and NO in the gas phase. In the presence of Ar/O2 mixture, the intrabubble oxidation of NO causes cavitation bubble depletion in O2 leading to the drop of H2O2 yield. On the other hand, it was found that for Ar/(20 vol.%)O2 mixture there is no influence of oxygen on HNO2 yield whatever the ultrasonic frequency; this is most likely explained by two processes: (i) HNO2 formation results from nitrate-ion thermolysis in the liquid reaction zone surrounding the cavitation bubble, and (ii) effective intrabubble oxidation of NOx species by oxygen to nitrate-ion.

Published
2016
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34. In-situ XAS study on the Cu and Ce local structural changes in a CuO–CeO2/Al2O3 catalyst under propane reduction and re-oxidation

Author

Geert Silversmit, M.F. Marie-Francoise Reniers, Dirk Poelman, Philippe Smet, María José Alonso Olea, Guy Marin, Sergey I. Nikitenko, Roger De Gryse, Hilde Poelman, Wim Bras, Veerle Balcaen, and Philippe M. Heynderickx

Subjects
X-ray absorption spectroscopy, Extended X-ray absorption fine structure, Absorption spectroscopy, Inorganic chemistry, 02 engineering and technology, General Chemistry, Atmospheric temperature range, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Heterogeneous catalysis, 01 natural sciences, Redox, 0104 chemical sciences, Catalysis, chemistry.chemical_compound, chemistry, Propane, Physical chemistry, General Materials Science, 0210 nano-technology
Abstract

The redox behaviour of a CuO–CeO2/Al2O3 catalyst is studied under propane reduction and re-oxidation. The evolution of the local Cu and Ce structure is studied with in-situ transmission X-ray absorption spectroscopy (XAS) at the Cu K and Ce L3 absorption edges. CuO and CeO2 structures are present in the catalyst as such. No structural effect on the local Cu structure is observed upon heating in He up to 873 K or after pre-oxidation at 423 K. Exposure to propane at reaction temperature (600–763 K) fully reduces the Cu2+ cations towards metallic Cu0. Quick EXAFS spectra taken during reduction show a small amount of intermediate Cu1+ species. Parallel to the CuO reduction, CeO2 is also reduced in the same temperature range. About 25% of the Ce4+ reduces rapidly to Ce3+ in the 610–640 K temperature interval, while beyond 640 K a further slower reduction of Ce4+ to Ce3+ occurs. At 763 K, Ce reduction is still incomplete with 32% of Ce3+. Re-oxidation of Cu and Ce is fast and brings back the original oxides. The propane reduction of the CuO–CeO2/Al2O3 catalyst involves both CuO and CeO2 reduction at similar temperatures, which is ascribed to an interaction between the two compounds.

Published
2009
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35. Vitamin C boosts ceria-based catalyst recycling

Author

Grégory Durand, Gilles Leturcq, Xavier Beaudoux, Sergey I. Nikitenko, Tony Chave, Matthieu Virot, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut des Biomolécules Max Mousseron [Pôle Chimie Balard] (IBMM), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Avignon Université (AU)

Subjects
chemistry.chemical_classification, Inorganic chemistry, Kinetics, Oxide, Mineral acid, Polishing, Sulfuric acid, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Ascorbic acid, 01 natural sciences, Pollution, 0104 chemical sciences, Catalysis, chemistry.chemical_compound, chemistry, Environmental Chemistry, 0210 nano-technology, Dissolution, ComputingMilieux_MISCELLANEOUS
Abstract

The facile, rapid, and complete reductive dissolution of CeO2 and ceria-based oxides, known to be highly refractive materials towards dissolution, is reported for the first time in very mild conditions. Ceria samples are dissolved at room temperature under stirring in a mixture composed of ascorbic acid and a dilute mineral acid. Normalized dissolution kinetics are compared as a function of the concentration of reactants, nature of the mineral acid, firing temperature and reactive surface area of considered oxides. Since ceria dissolution can represent a promising alternative for the recycling of automotive catalysts, solid oxide fuel cells, polishing powders, organic chemistry catalysts, sensors, etc., the potential application of the proposed procedure is then studied through the dissolution of catalyst surrogates and complex oxides: Pt/CeO2, (Ce0.75Zr0.25)O2, and (Ce0.8Tb0.2)O2. Whatever the considered sample, the complete and congruent (for mixed oxides) oxide dissolution is observed in 0.5 M ascorbic acid in the presence of dilute nitric or sulfuric acid. For Pt/CeO2 samples, ceria dissolution goes with Pt aggregation which can be easily recovered from the solution after processing due to its high stability in this medium. This eco-friendly and efficient method appears very promising for catalyst recycling in comparison to conventional procedures. After rigorous characterization of the investigated oxides (BET, SEM-EDX, XRD, TGA), dissolution progress is evaluated with ICP-OES and SEM measurements. The dissolution mechanism is then investigated with UV-Vis, ATR-FTIR and ESR spectroscopies and a general dissolution mechanism is proposed.

Published
2016
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36. Spectroscopy of Sonoluminescence and Sonochemistry in Water Saturated with N 2 –Ar Mixtures

Author

Warda Ben Messaoud, Temim Ouerhani, Rachel Pflieger, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Chemistry, Radical, Analytical chemistry, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, 01 natural sciences, Dissociation (chemistry), Spectral line, 0104 chemical sciences, Surfaces, Coatings and Films, Sonochemistry, Sonoluminescence, Excited state, Materials Chemistry, Molecule, [CHIM]Chemical Sciences, Physical and Theoretical Chemistry, 0210 nano-technology, Spectroscopy, ComputingMilieux_MISCELLANEOUS
Abstract

Sonoluminescence spectra in relation with sonochemical activity of water sparged with Ar/N2 gas mixtures were systematically studied at two ultrasonic frequencies (20 and 359 kHz). At 20 kHz, solely the molecular emission of OH (A(2)Σ(+)-X(2)Πi) is observed in addition to a broad continuum typical for multibubble sonoluminescence. On the contrary, at high frequency a second emission band is present around 336 nm which is assigned to the NH (A(3)Π-X(3)Σ(-)) system. In addition, the sonolysis of a 0.2 M NH3·H2O solution at 359 kHz in the presence of pure Ar yields the emission bands of NH (A(3)Π - X(3)Σ(-)) (336 nm) and NH (C(1)Π-A(1)Δ) (322 nm) systems confirming the sonochemical production of NH radicals. The N2 (C(3)Πu-B(3)Πg) emission band is absent at both frequencies. This uncommon phenomenon can be explained by the quenching of the N2 (C(3)Πu) excited state with water molecules inside the bubbles. The sonoluminescence of NH radicals at 359 kHz indicates more effective intrabubble dissociation of N2 molecules at high ultrasonic frequency compared to low-frequency (20 kHz) ultrasound. Its absence at 20 kHz may also be related to strong quenching, e.g., by water molecules. The kinetic study of the formation of principal sonochemical products (H2, H2O2, HNO3, HNO2) confirmed the more drastic conditions produced during bubble collapse at higher ultrasonic frequency.

Published
2015
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37. Toward a new paradigm for sonochemistry: Short review on nonequilibrium plasma observations by means of MBSL spectroscopy in aqueous solutions

Author

Rachel Pflieger, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Aqueous solution, Acoustics and Ultrasonics, Chemistry, Organic Chemistry, Analytical chemistry, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Sonochemistry, Inorganic Chemistry, Sonoluminescence, 13. Climate action, Chemical Engineering (miscellaneous), Environmental Chemistry, Electron temperature, [CHIM]Chemical Sciences, Radiology, Nuclear Medicine and imaging, Emission spectrum, Ionization energy, 0210 nano-technology, Spectroscopy, Vibrational temperature, ComputingMilieux_MISCELLANEOUS
Abstract

This review summarizes recent studies of multibubble sonoluminescence (MBSL) in aqueous media in order to highlight new insights into the origin of the sonochemical activity. The observation of OH(C2Σ+-A2Σ+) emission band and a spectroscopic analysis of OH(A2Σ+-X2Πi) emission band in MBSL of water pre-equilibrated with noble gases revealed the formation of a nonequilibrium plasma inside the collapsing bubble (Te>Tv>Tr, where Te is an electron temperature, Tv is a vibrational temperature and Tr is a rotational (gas) temperature). The Te and Tv estimated using OH(A2Σ+-X2Πi) emission band increase with ultrasonic frequency. In Xe the Tv of OH(A2Σ+) state is much higher than in Ar most probably due to the lower ionization potential of Xe. The MBSL of C2∗ Swan band (d3Πg-a3Πu) measured in aqueous tert-butanol (t-BuOH) solutions correlates with the data obtained for OH(A2Σ+-X2Πi) emission band. Analysis of the gaseous products of t-BuOH sonolysis revealed a significant sonochemical activity even at high t-BuOH concentration when MBSL is totally quenched, indicating that drastic intrabubble conditions (plasma) are not necessarily accompanied by sonoluminescence. The nonequilibrium plasma model of cavitation allows to explain the reverse carbon isotope effect observed during the sonolysis of water in the presence of Ar/CO gas mixture.

Published
2015
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38. Influence of He and Ar Flow Rates and NaCl Concentration on the Size Distribution of Bubbles Generated by Power Ultrasound

Author

Judy Lee, Rachel Pflieger, Muthupandian Ashokkumar, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Center for Microbial Genetics and Genomics, Northern Arizona University [Flagstaff], School of Chemistry [Melbourne], Faculty of Science [Melbourne], University of Melbourne-University of Melbourne, and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Coalescence (physics), Aqueous solution, Materials science, Bubble, Diffusion, Analytical chemistry, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Concentration ratio, 0104 chemical sciences, Surfaces, Coatings and Films, Volumetric flow rate, Physics::Fluid Dynamics, Sonoluminescence, Materials Chemistry, Gaseous diffusion, [CHIM]Chemical Sciences, Physical and Theoretical Chemistry, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

A technique based on pulsed ultrasound and sonoluminescence emission was used to measure the size and size distribution of bubbles generated by 355 kHz power ultrasound under continuous Ar or He flow in aqueous NaCl solutions. It was observed that the bubble size strongly decreased with increasing NaCl concentration and that this decrease was much stronger than in solutions presaturated with Ar or He. This size decrease is attributed to the combination of the salting-out effect of the salt and the introduction of bubble nuclei by the continuous gas flow. Besides, the comparison of Ar and He bubbles underlines the effect of the gas diffusion coefficient on the bubble size reached.

Published
2015
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39. Sonochemical water splitting in the presence of powdered metal oxides

Author

Tony Chave, Philippe Moisy, Sergey I. Nikitenko, Matthieu Virot, Vincent Morosini, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Acoustics and Ultrasonics, Inorganic chemistry, Oxide, Nucleation, Nanoparticle, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Sonochemistry, Inorganic Chemistry, Metal, chemistry.chemical_compound, Mechanochemistry, Chemical Engineering (miscellaneous), Environmental Chemistry, Radiology, Nuclear Medicine and imaging, ComputingMilieux_MISCELLANEOUS, Organic Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, Chemical engineering, visual_art, visual_art.visual_art_medium, Water splitting, Particle, 0210 nano-technology
Abstract

Kinetics of hydrogen formation was explored as a new chemical dosimeter allowing probing the sonochemical activity of argon-saturated water in the presence of micro- and nano-sized metal oxide particles exhibiting catalytic properties (ThO2, ZrO2, and TiO2). It was shown that the conventional sonochemical dosimeter based on H2O2 formation is hardly applicable in such systems due to catalytic degradation of H2O2 at oxide surface. The study of H2 generation revealed that at low-frequency ultrasound (20 kHz) the sonochemical water splitting is greatly improved for all studied metal oxides. The highest efficiency is observed for relatively large micrometric particles of ThO2 which is assigned to ultrasonically-driven particle fragmentation accompanied by mechanochemical water molecule splitting. The nanosized metal oxides do not exhibit particle size reduction under ultrasonic treatment but nevertheless yield higher quantities of H2. The enhancement of sonochemical water splitting in this case is most probably resulting from better bubble nucleation in heterogeneous systems. At high-frequency ultrasound (362 kHz), the effect of metal oxide particles results in a combination of nucleation and ultrasound attenuation. In contrast to 20 kHz, micrometric particles slowdown the sonolysis of water at 362 kHz due to stronger attenuation of ultrasonic waves while smaller particles show a relatively weak and various directional effects.

Published
2015
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40. Spectroscopic and Electrochemical Studies of U(IV)−Hexachloro Complexes in Hydrophobic Room-Temperature Ionic Liquids [BuMeIm][Tf2N] and [MeBu3N][Tf2N]

Author

P. Moisy, C. Le Naour, Sergey I. Nikitenko, D. Trubert, C. Cannes, Institut de Physique Nucléaire d'Orsay (IPNO), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Absorption spectroscopy, Chemistry, Analytical chemistry, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Electrochemistry, 01 natural sciences, 0104 chemical sciences, Ion, Inorganic Chemistry, chemistry.chemical_compound, Ultraviolet visible spectroscopy, Ionic liquid, Physical chemistry, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Staircase voltammetry, Physical and Theoretical Chemistry, Rotating disk electrode, 0210 nano-technology, Voltammetry
Abstract

The behavior of U(IV) octahedral complexes [cation]2[UCl6], where the [cation]+ is [BuMeIm]+ and [MeBu3N]+, is studied using UV/visible spectroscopy, cyclic staircase voltammetry, and rotating disk electrode voltammetry in hydrophobic room-temperature ionic liquids (RTILs) [BuMeIm][Tf2N] and [MeBu3N][Tf2N], where BuMeIm+ and MeBu3N+ are 1-butyl-3-methylimidazolium and tri-n-butylmethylammonium cations, respectively, and Tf2N- is the bis(trifluoromethylsulfonyl)imide anion. The absorption spectra of [cation]2[UCl6] complexes in the RTIL solutions are similar to the diffuse solid-state reflectance spectra of the corresponding solid species, indicating that the octahedral complex UCl6(2-) is the predominant chemical form of U(IV) in Tf2N--based hydrophobic ionic liquids. Hexachloro complexes of U(IV) are stable to hydrolysis in the studied RTILs. Voltammograms of UCl(6)2- at the glassy carbon electrode in both RTILs and at the potential range of -2.5 to +1.0 V versus Ag/Ag(I) reveal the following electrochemical couples: UCl6-/UCl6(2-) (quasi-reversible system), UCl(6)2-/UCl6(3-) (quasi-reversible system), and UCl(6)2-/UCl6(Tf2N)x-3+x (irreversible reduction). The voltammetric half-wave potential, Ep/2, of the U(V)/U(IV) couple in [BuMeIm][Tf2N] is positively shifted by 80 mV compared with that in [MeBu3N][Tf2N]. The positive shift in the Ep/2 value for the quasi-reversible U(IV)/U(III) couple is much greater (250 mV) in [BuMeIm][Tf2N]. Presumably, the potential shift is due to the specific interaction of BuMeIm+ with the uranium-hexachloro complex in ionic liquid. Scanning the negative potential to -3.5 V in [MeBu3N][Tf2N] solutions of UCl6(2-) reveals the presence of an irreversible cathodic process at the peak potential equal to -3.12 V (at 100 mV/s and 60 degrees C), which could be attributed to the reduction of U(III) to U(0).

Published
2005
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41. Catalytic dissolution of ceria–lanthanide mixed oxides provides environmentally friendly partitioning of lanthanides and platinum

Author

Tony Chave, Nicolas Clavier, Nicolas Dacheux, Xavier Beaudoux, Matthieu Virot, Gilles Leturcq, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Interfaces de Matériaux en Evolution (LIME), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Lanthanide, Inorganic chemistry, Oxide, chemistry.chemical_element, 02 engineering and technology, engineering.material, 010402 general chemistry, Platinum nanoparticles, 01 natural sciences, Industrial and Manufacturing Engineering, Catalysis, chemistry.chemical_compound, Nitric acid, Materials Chemistry, [CHIM]Chemical Sciences, Dissolution, ComputingMilieux_MISCELLANEOUS, Chemistry, Metals and Alloys, 021001 nanoscience & nanotechnology, 6. Clean water, 0104 chemical sciences, engineering, Noble metal, 0210 nano-technology, Platinum
Abstract

The reductive dissolution of cerium–lanthanide mixed oxides was investigated under mild conditions in weakly acid media. The dissolution is catalyzed by platinum nanoparticles (Pt NPs) deposited onto oxide surfaces. The deposition of Pt NPs was performed by sonochemical reduction of Pt(IV). The dissolution efficiency was studied as a function of different parameters such as stirring, sonication at 20 kHz, dissolution media and oxide composition. The quantitative dissolution of these oxides can be performed in 0.25 M HNO 3 –1 M HCOOH–0.2 M [N 2 H 5 ][NO 3 ] and 0.125 M H 2 SO 4 –1 M HCOOH under stirring at 40 °C in the presence of argon, or in 0.125 M H 2 SO 4 under sonication in the presence of Ar–CO gas mixture at 40 °C. In nitric acid solutions mechanical stirring is more efficient than sonication due to the secondary denitration triggered by ultrasound. The incorporation of trivalent (Gd, Nd) or tetravalent (Tb) lanthanides into the ceria matrix resulted in faster dissolution. After dissolution, lanthanides and platinum can be separated by simple filtration. The catalytic dissolution of ceria-based mixed oxides offers a simple way of lanthanide and noble metal partitioning which could appear of interest for catalyst recycling.

Published
2015
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42. Autocatalytic sonolysis of iron pentacarbonyl in room temperature ionic liquid [BuMeIm][Tf2N]

Author

Rachel Pflieger, Moulay Tahar Sougrati, Lorenzo Stievano, Sergey I. Nikitenko, Lenaic Lartigue, Yannick Guari, Joulia Larionova, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Inorganic chemistry, General Physics and Astronomy, Nanoparticle, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, 01 natural sciences, Decomposition, 0104 chemical sciences, Iron pentacarbonyl, Sonochemistry, Autocatalysis, chemistry.chemical_compound, chemistry, Ionic liquid, Tetralin, Physical and Theoretical Chemistry, 0210 nano-technology
Abstract

International audience; The autocatalytic sonochemical reaction of Fe(CO)5 decomposition in [BuMeIm][Tf2N] provides iron nanoparticles in higher yields than in tetralin. Such a difference is explained by the higher decomposition of the intermediate Fe3(CO)12 according to the two-sites model of the sonochemical reactions and the specific properties of the ionic liquid.

Published
2011
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43. Influence of Ultrasonic Frequency on Swan Band Sonoluminescence and Sonochemical Activity in Aqueous tert -Butyl Alcohol Solutions

Author

Tony Chave, Rachel Pflieger, Sergey I. Nikitenko, Abdoul Aziz Ndiaye, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Chemistry, Bubble, Analytical chemistry, Rotational temperature, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Spectral line, 0104 chemical sciences, Surfaces, Coatings and Films, Sonochemistry, Sonoluminescence, 13. Climate action, Materials Chemistry, Electron temperature, [CHIM]Chemical Sciences, Emission spectrum, Physical and Theoretical Chemistry, Ionization energy, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

The multibubble sonoluminescence (MBSL) spectra of t-BuOH aqueous solutions submitted to power ultrasound at 20, 204, 362, and 613 kHz show emissions for the Δυ = -1 to Δυ = +2 vibrational sequences of C2* Swan system (d(3)Πg → a(3)Πu). The Δυ=+2 emission overlaps with the CH(A-X) emission band. The maximal Swan band emission is observed when the MBSL of water itself is almost completely quenched. In general, MBSL is more intense at high-frequency compared to 20 kHz ultrasound. However, in the presence of Xe, the MBSL of C2* at 20 kHz is so bright that it can be seen by the unaided eye as a blue glow in the close vicinity of the ultrasonic tip. The intensity of the C2* band emission exhibits a maximum vs t-BuOH concentration: 0.1-0.2 M at 20 kHz and (1-8) × 10(-3) M at high-frequency ultrasound. Such a huge difference is attributed to a much smaller bubble size at high ultrasonic frequency or, in other words, to a much higher bubble surface/volume ratio providing more efficient saturation of the bubble interior with t-BuOH vapors and to the fact that high frequency bubbles remain active for many more cycles than 20 kHz ones, thus accumulating more hydrocarbon decomposition products. Simulation of the emission spectra using Specair software demonstrated the absence of thermal equilibrium for C2* radicals (Tv > Tr), where Tv and Tr are the vibrational and the rotational temperature, respectively. In Ar, Tv decreases with increasing t-BuOH concentration reaching a steady value in the concentration domain that corresponds to C2* emission maximum intensity. In the presence of Xe an extremely high Tv is obtained, which is explained by the relatively low ionization potential of Xe providing a higher electron temperature of nonequilibrium plasma generated during bubble collapse. Analysis of the gaseous products of t-BuOH sonolysis reveals a significant sonochemical activity even at high t-BuOH concentration when MBSL is totally quenched, indicating that drastic conditions could be produced also within nonsonoluminescing cavitation bubbles.

Published
2014
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44. Sonohydrothermal Synthesis of Nanostructured (Ce,Zr)O2 Mixed Oxides with Enhanced Catalytic Performance

Author

Patrick Pochon, Tony Chave, Joulia Larionova, Yannick Guari, Sergey I. Nikitenko, Camille Cau, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Chimie moléculaire et organisation du solide (CMOS), Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Département RadioChimie et Procédés (DRCP), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Coprecipitation, Inorganic chemistry, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 7. Clean energy, 01 natural sciences, Hydrothermal circulation, Catalysis, Sonochemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Wet oxidation, Physical and Theoretical Chemistry, ComputingMilieux_MISCELLANEOUS, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, General Energy, chemistry, Mixed oxide, 0210 nano-technology, Mesoporous material, Platinum, Nuclear chemistry
Abstract

We report for the first time evidence of sonochemical activity under hydrothermal conditions. Sonolysis of H2O and D2O using 20 kHz power ultrasound at 200 °C and 13 bar in the presence of argon yields H2 and D2 respectively. Formation of hydrogen peroxide is not observed because of its thermal instability. The simultaneous sonohydrothermal treatment was used for the preparation of Ce0.5Zr0.5O2 nanocrystalline mixed oxide with external mesoporous surface area higher than that of similar material prepared by ultrasonically assisted coprecipitation followed by hydrothermal treatment. The obtained mixed oxide loaded with 1.5 wt % of platinum exhibits high activity and stability in catalytic wet air oxidation of formic acid at low temperature.

Published
2013
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45. Uranium carbide dissolution in nitric solution: Sonication vs. silent conditions

Author

Tony Chave, Sergey I. Nikitenko, Philippe Moisy, Matthieu Virot, Stéphanie Szenknect, Nicolas Dacheux, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Interfaces de Matériaux en Evolution (LIME), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Nuclear and High Energy Physics, Nitrous acid, Sonication, Induction period, Inorganic chemistry, Kinetics, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, equipment and supplies, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Sonochemistry, chemistry.chemical_compound, Nuclear Energy and Engineering, chemistry, Nitric acid, General Materials Science, Uranium carbide, 0210 nano-technology, Dissolution, ComputingMilieux_MISCELLANEOUS
Abstract

The dissolution of uranium carbide (UC) in nitric acid media is considered by means of power ultrasound (sonication) or magnetic stirring. The induction period required to initiate UC dissolution was found to be dramatically shortened when sonicating a 3 M nitric solution (Ar, 20 kHz, 18 W cm −2 , 20 °C). At higher acidity, magnetic stirring offers faster dissolution kinetics compared to sonication. Ultrasound-assisted UC dissolution is found to be passivated after ∼60% dissolution and remains incomplete whatever the acidity which is confirmed by ICP–AES, LECO and SEM–EDX analyses. In general, the kinetics of UC dissolution is linked to the in situ generation of nitrous acid in agreement with the general mechanism of UC dissolution; the nitrous acid formation is reported to be faster under ultrasound at low acidity due to the nitric acid sonolysis. The carbon balance shared between the gaseous, liquid, and solid phases is strongly influenced by the applied dissolution procedure and HNO 3 concentration.

Published
2013
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46. Absence of 232,230,228 Th enhancement decay by ultrasound exposure

Author

Virginie Cousin, Rachel Pflieger, Sergey I. Nikitenko, Jean Aupiais, Philippe Moisy, DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Département RadioChimie et Procédés (DRCP)

Subjects
Thesaurus (information retrieval), Information retrieval, Chemistry, business.industry, Ultrasound, Ultrasound exposure, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, 010305 fluids & plasmas, 0103 physical sciences, [CHIM]Chemical Sciences, Physical and Theoretical Chemistry, 0210 nano-technology, business, [CHIM.RADIO]Chemical Sciences/Radiochemistry, ComputingMilieux_MISCELLANEOUS
Abstract

We report on our attempt to reproduce the 228Th decay enhancement under the effect of power ultrasound claimed recently in the literature. The evolution of natural thorium isotopic composition (232Th, 230Th, and 228Th) in various aqueous solutions submitted to 20 kHz power ultrasound (0.18 W mL−1, 20 ºC, Ar). The radioactivities of the three isotopes of thorium (232Th, 230Th and 228Th) were followed by α liquid scintillation counting technique. No change was detected during ultrasonic irradiation. Our results demonstrate that under the studied conditions the rate of Th isotopes radioactive decay is not modified under the effect of ultrasound on aqueous solutions of thorium salts.

Published
2013
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47. Iron carbide nanoparticles growth in room temperature ionic liquids [C n -MIM][BF4] (n = 12, 16)

Author

Lorenzo Stievano, Yannick Guari, Claudio Sangregorio, Sergey I. Nikitenko, Camille Cau, Christian Guérin, Joulia Larionova, Jérôme Long, Moulay Tahar Sougrati, Lenaic Lartigue, Xavier Dumail, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Chimie moléculaire et organisation du solide (CMOS), Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Agrégats Moléculaires et Matériaux Inorganiques (LAMMI), Centre National de la Recherche Scientifique (CNRS)-Université Montpellier 2 - Sciences et Techniques (UM2), Dipartimento di Chimica, Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI)-Italian Interuniversity Consortium on Materials Science and Technology, Laboratory of Molecular Magnetism, Dipartimento di Chimica e UdR INSTM di Firenze, and Dipartimento di Chimica e UdR INSTM di Firenze

Subjects
Materials science, Inorganic chemistry, Nanoparticle, Bioengineering, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Carbide, chemistry.chemical_compound, Mössbauer spectroscopy, Cementite, Iron carbide, Ionic Liquids, Magnetic properties, [CHIM.COOR]Chemical Sciences/Coordination chemistry, General Materials Science, Compounds of carbon, MAGNETIC-PROPERTIES, HYDROGENATION REACTIONS, OXIDE NANOPARTICLES, GOLD NANOPARTICLES, BILAYER-MEMBRANES, PRECURSORS, NANORODS, NANOSTRUCTURES, NANOCOMPOSITE, NANOCRYSTALS, ComputingMilieux_MISCELLANEOUS, chemistry.chemical_classification, Thermal decomposition, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, chemistry, Modeling and Simulation, Ionic liquid, X-ray crystallography, 0210 nano-technology
Abstract

The thermal decomposition of Fe x (CO) y precursors for the synthesis of nanoparticles of iron carbides and their superstructures with sizes ranging from 2.8 to 15.1 nm is developed using imidazolium-based ionic liquids as solvents, stabilizers, and carbon source. A study of the influence of some synthesis parameters such as the heating temperature, nature, and concentration of the iron carbonyl precursor and chain length of the N-alkyl substituent on the imidazolium ring on the size and organization of the iron carbide nanoparticles is presented. These iron carbides nano-objects were characterized by infra-red spectroscopy, transmission electronic microscopy, powder X-ray diffraction, Mossbauer spectroscopy, and magnetic analyses.

Published
2013
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48. Luminescence of Trivalent Lanthanide Ions Excited by Single-Bubble and Multibubble Cavitations

Author

Rachel Pflieger, Sergey I. Nikitenko, Bertrand Siboulet, Julia Schneider, Helmuth Möhwald, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Max Planck Institute of Colloids and Interfaces, Max-Planck-Gesellschaft, Modélisation Mésoscopique et Chimie Théorique (LMCT), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Lanthanide, Quenching (fluorescence), Photoluminescence, Chemistry, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, 01 natural sciences, 0104 chemical sciences, Surfaces, Coatings and Films, Ion, Photoexcitation, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Sonoluminescence, Excited state, Materials Chemistry, [CHIM]Chemical Sciences, Physical and Theoretical Chemistry, 0210 nano-technology, Luminescence
Abstract

International audience; This article focuses on the possibility of exciting some lanthanides (Ce3+, Tb3+, Gd3+, and Eu3+) by ultrasound in aqueous solutions. Depending on the lanthanide ions and on the acoustic cavitation conditions (single-bubble or multibubble systems), the excitation mechanism is shown to be photoexcitation (e.g., for Ce3+) or collision-induced excitation (e.g., for Tb3+). The sonoluminescence of Tb3+ is studied in detail at various ultrasonic frequencies, allowing quantification of the amount of quenching. The latter is much stronger in sonoluminescence than in photoluminescence due to the particular properties of acoustic cavitation. Complexation with citrate ions enhances manifold sonoluminescence of lanthanides due to reduction of intra- and inner-molecular quenching.

Published
2013
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49. Nonequilibrium vibrational excitation of OH radicals generated during multibubble cavitation in water

Author

Jean-François Dufrêche, John J. Molina, Rachel Pflieger, Bertrand Siboulet, Abdoul Aziz Ndiaye, Sergey I. Nikitenko, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Modélisation Mésoscopique et Chimie Théorique (LMCT), PHysicochimie des Electrolytes et Nanosystèmes InterfaciauX (PHENIX), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and ANR-10-BLAN-0810,NEQSON,Sonochimie en condition hors équilibre(2010)

Subjects
Argon, chemistry.chemical_element, 02 engineering and technology, Plasma, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Spectral line, 0104 chemical sciences, Sonochemistry, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Sonoluminescence, chemistry, Excited state, Cavitation, [CHIM]Chemical Sciences, Physical and Theoretical Chemistry, Atomic physics, 0210 nano-technology, Excitation
Abstract

International audience; The sonoluminescence (SL) spectra of OH(A2Σ+) excited state produced during the sonolysis of water sparged with argon were measured and analyzed at various ultrasonic frequencies (20, 204, 362, 609, and 1057 kHz) in order to determine the intrabubble conditions created by multibubble cavitation. The relative populations of the OH(A2Σ+) v′ = 1–4 vibrational states as well as the vibronic temperatures (Tv, Te) have been calculated after deconvolution of the SL spectra. The results of this study provide evidence for nonequilibrium plasma formation during sonolysis of water in the presence of argon. At low ultrasonic frequency (20 kHz), a weakly excited plasma with Brau vibrational distribution is formed (Te ∼ 0.7 eV and Tv ∼ 5000 K). By contrast, at high-frequency ultrasound, the plasma inside the collapsing bubbles exhibits Treanor behavior typical for strong vibrational excitation. The Te and Tv values increase with ultrasonic frequency, reaching Te ∼ 1 eV and Tv ∼ 9800 K at 1057 kHz.

Published
2012
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50. Mechanism of PtIV Sonochemical Reduction in Formic Acid Media and Pure Water

Author

Tony Chave, Serge Nitsche, Sergey I. Nikitenko, Nathalie M. Navarro, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Paul Cézanne - Aix-Marseille 3, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Hydrogen, Reducing agent, Formic acid, Radical, Organic Chemistry, Inorganic chemistry, chemistry.chemical_element, 02 engineering and technology, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Platinum nanoparticles, 01 natural sciences, Catalysis, 0104 chemical sciences, Sonochemistry, chemistry.chemical_compound, chemistry, Oxidizing agent, [CHIM]Chemical Sciences, 0210 nano-technology, Platinum, ComputingMilieux_MISCELLANEOUS
Abstract

Sonochemical synthesis of platinum nanoparticles (Pt NPs) in formic acid solutions and pure water was investigated using a 20 kHz ultrasonic irradiation. The obtained results gave new insights on the underneath Pt(IV) reduction mechanism in formic acid media under argon and in pure water under Ar/CO atmosphere. It was shown that in pure water sonochemical reduction of platinum ions occurs by hydrogen issued from homolytic water molecule split. Pt(IV) ion reduction appears to be a very slow process under argon atmosphere in pure water due to formation of oxidizing species like OH radicals and H(2)O(2) leading to reoxidation of intermediate Pt(II) ions. Sonochemical reduction is accelerated manifold in the presence of formic acid or Ar/CO gas mixture. Solution and gas-phase analyses reveal that both CO and HCOOH act as OH(.) radical scavenger and reducing agent under ultrasonic irradiation. Their ability to reduce platinum ions at room temperature is enhanced due to the local heating in the liquid shell surround the cavitation bubble. An innovative synthesis route for monodispersed Pt NPs in pure water without any templates or capping agents in the presence of Ar/CO gas mixture is then proposed. Obtained Pt NPs within the range of 2-3 nm exhibited a strong stability towards sedimentation in water. Since Ar/CO atmosphere is the only restriction of the process, this procedure can be applied in various media and is also compatible with a large array of experimental conditions.

Published
2012
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