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1. Size and structure of hexanuclear plutonium oxo-hydroxo clusters in aqueous solution from synchrotron analysis

Author

Thomas Dumas, Matthieu Virot, Denis Menut, Christelle Tamain, Cyril Micheau, Sandrine Dourdain, and Olivier Diat

Subjects
plutonium, clusters, saxs, exafs, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798, Crystallography, QD901-999
Abstract

The size and shape of a water-soluble hexanuclear plutonium cluster were probed by combining synchrotron small-angle X-ray scattering (SAXS) and extended X-ray absorption fine structure (EXAFS). A specific setup coupling both techniques and dedicated to radioactive samples on the MARS beamline endstation at Synchrotron SOLEIL is described. The plutonium hexanuclear cores are well stabilized by the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid ligands and this allows a good evaluation of the setup to probe the very small plutonium core. The results show that, in spite of the constrained conditions required to avoid any risk of sample dispersion, the flux and the sample environment are optimized to obtain a very good signal-to-noise ratio, allowing the detection of small plutonium aggregates in an aqueous phase. The structure of the well defined hexanuclear cluster has been confirmed by EXAFS measurements in solution and correlated with SAXS data processing and modelling. An iterative comparison of classical fit models (Guinier or sphere form factor) with the experimental results allowed a better interpretation of the SAXS signal that will be relevant for future work under environmentally relevant conditions.

Published
2022
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2. Deuterated Malonamide Synthesis for Fundamental Research on Solvent Extraction Systems

Author

Cyril Micheau, Yuki Ueda, Kazuhiro Akutsu-Suyama, Damien Bourgeois, and Ryuhei Motokawa

Subjects
General Chemical Engineering, General Chemistry
Abstract

Malonamide derivatives, which are the most extensively investigated extractants for solvent extraction of lanthanides, actinides, and platinum group metal ions, were deuterated by using Pd/C and Rh/C catalysts in a D2O/2-propanol mixture. This method replaces 1H atoms in the malonamides with 2H atoms at a controllable deuteration rate. The maximum rate reached about 75%, determined by nuclear magnetic resonance and electrospray ionization – mass spectrometry. The extraction behavior of metal ions by the malonamides was unchanged by the deuteration. Deuterated malonamides are a powerful tool for fundamental research on solvent extraction systems and for structural analysis of organic phases. The large difference in the cross section of coherent neutron scattering between 1H and 2H leads to a large difference in neutron scattering length density of malonamide derivatives before and after the deuteration. Therefore, using deuterated malonamides in small-angle neutron scattering and neutron reflectivity studies may help to reveal the microscopic structure of the specific solute species in the bulk organic phase and at the liquid–liquid interface, respectively. In this paper, we report the advantage of the deuterated malonamides for a contrast-matching method in the SANS experiment. This deuteration method could be generalized and extended to a wide variety of extractant molecules.

Published
2023
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3. Relevance of formation conditions to the size, morphology and local structure of intrinsic plutonium colloids

Author

Olivier Diat, Laurent Venault, Sandrine Dourdain, Thomas Dumas, Matthieu Virot, Philippe Moisy, Denis Menut, Cyril Micheau, Pier Lorenzo Solari, 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), 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), Tri ionique par les Systèmes Moléculaires auto-assemblés (LTSM), 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), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Ions aux Interfaces Actives (L2IA), 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), 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)-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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'Energie Atomique, Saclay (CEA)

Subjects
X-ray absorption spectroscopy, Materials science, Absorption spectroscopy, Small-angle X-ray scattering, Scattering, Materials Science (miscellaneous), Nanoparticle, Ionic bonding, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010501 environmental sciences, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Colloid, Chemical physics, Particle size, [CHIM.RADIO]Chemical Sciences/Radiochemistry, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science
Abstract

International audience; Fundamental knowledge about plutonium intrinsic colloids is a key issue for the prediction of plutonium transport and release rates in the environment. Recent studies demonstrated that the particle size and surface properties of intrinsic Pu colloids are strongly influenced by the preparation method. In this work, a combination of synchrotron small angle X-ray scattering (SAXS) with X-ray absorption spectroscopy (XAS) is used to characterize two kinds of stable plutonium intrinsic colloids prepared by hydrolysis of Pu(IV) ionic species and sonolysis of PuO2 in pure water. Despite their similarities, the multi-scale structural properties of these colloidal suspensions are found to be strongly influenced by the synthesis route. The hydrolysis approach leads to spherical nanoparticles of ca. 2.0 nm, whereas sonolytic colloids show elongated structures measuring 5.7 nm of thickness and >30 nm long. This difference results from the synthesis mechanism and can be attributed to nanoparticle aggregation in the absence of capping-ions. The results obtained by both SAXS and XAS approaches converge in the description of Pu(IV) intrinsic colloids as core–shell nanoparticles made up of a PuO2 core covered with a disordered Pu–O shell characterized by a splitting of Pu–O and Pu–Pu distances and an associated strong increase of associated DWF parameters. The local distortions of both Pu–O and Pu–Pu coordination spheres observed by XAS seem to be correlated with the nanoparticle shrinking probed by SAXS rather from the contribution of higher Pu oxidation states. The stabilization of the hydrolytic colloidal particles is further suggested from SAXS simulation to result from interaction with counter-ions from the medium.

Published
2020
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4. 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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5. Recovery of tantalum from synthetic sulfuric leach solutions by solvent extraction with phosphonate functionalized ionic liquids

Author

Manuel Lejeune, Stéphane Pellet-Rostaing, Micheline Draye, Stephanie Michel, Guilhem Arrachart, Sophie Legeai, Raphaël Turgis, Cyril Micheau, Tri ionique par les Systèmes Moléculaires auto-assemblés (LTSM), 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 de Chimie Moléculaire et Environnement (LCME), 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), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), and ANR-13-CDII-0010,SILEXE,Liquides ioniques pour le recyclage de métaux stratégiques par procédé d'extraction/électrodéposition(2013)

Subjects
Chemistry, Inorganic chemistry, Extraction (chemistry), Metals and Alloys, Tantalum, food and beverages, chemistry.chemical_element, Sulfuric acid, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Phosphonate, 6. Clean water, Industrial and Manufacturing Engineering, 0104 chemical sciences, Partition coefficient, chemistry.chemical_compound, Ionic liquid, Materials Chemistry, [CHIM]Chemical Sciences, 0210 nano-technology, Solvent extraction, [CHIM.OTHE]Chemical Sciences/Other, ComputingMilieux_MISCELLANEOUS
Abstract

A series of phosphonate-functionalized task-specific ionic liquids (TSILs) have been synthesized and studied for selective extraction of tantalum from a sulfuric acid medium. The results described here show that high distribution coefficient values can be achieved for the selective separation of tantalum (Ta). Such a system can be used as an alternative to TBP for the separation and purification of tantalum by solvent extraction.

Published
2019
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6. Nanoparticle foam flotation for caesium decontamination using a pH-sensitive surfactant

Author

Olivier Diat, Cyril Micheau, Pierre Bauduin, Luc Girard, Dmytro Dedovets, Ions aux Interfaces Actives (L2IA), 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)-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 ANR-17-CE08-0016,FOAMEX,Mousses de lixiviation pour l'extraction de métaux des déchets électroniques(2017)

Subjects
Prussian blue, Materials Science (miscellaneous), Extraction (chemistry), Nanoparticle, chemistry.chemical_element, Foaming agent, 02 engineering and technology, Human decontamination, 010501 environmental sciences, 021001 nanoscience & nanotechnology, 01 natural sciences, chemistry.chemical_compound, chemistry, Pulmonary surfactant, Chemical engineering, Caesium, Surface charge, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science
Abstract

Ion extraction processes show some limitations related to their selectivity, efficiency, cost and ecological footprint. The recent Fukushima event has stimulated the hunt for innovative extraction processes of the caesium ion. Here, we propose a caesium foam flotation process of a highly selective complexing agent, namely the copper based Prussian blue analogue (Cu-PBA), using a pH-sensitive foaming agent (collector): a polyethoxylated amine surfactant (Ethomeen®). The foaming properties, surface charge and surface activity of this complex chemical system have been investigated as a function of pH. It was demonstrated that the pH controls the flotation efficiency through electrostatic interactions between the surfactant and the Cu-PBA. The flotation was highly efficient for pH 10, all of the Cu-BPA remained in the foaming solution and was not extracted in the foam. As a consequence, reversible extraction/de-extraction of the Cu-PBA was made possible through pH cycles, which enables the recycling of the surfactant, reducing both the cost and the environmental impact of the overall process.

Published
2019
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7. Microfluidic comparative study of foam flow between a classical and a pH sensitive surfactant

Author

Nicolas Pannacci, Loïc Barré, Elisabeth Rosenberg, and Cyril Micheau

Subjects
Double layer (biology), Chromatography, Morphology (linguistics), Sodium, Microfluidics, chemistry.chemical_element, Context (language use), 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, chemistry.chemical_compound, Colloid and Surface Chemistry, Chemical engineering, Pulmonary surfactant, chemistry, 0103 physical sciences, lipids (amino acids, peptides, and proteins), Dodecanol, cardiovascular diseases, Enhanced oil recovery, 010306 general physics, 0210 nano-technology
Abstract

Comparative study between foams made of a pH sensitive surfactant, nonaoxyethylene oleylether carboxylic acid (AKYPO ® RO 90 VG) and a classical foaming surfactant, sodium dodecyl sulphate (SDS) was realised using simple microfluidic devices in the scope of Enhanced Oil Recovery (EOR). The influence of injecting fluid parameters such as gas and foaming liquid pressure was investigated and discussed in terms of foam morphology, and lamellae stability and curvature radii. The increasing stability of AKYPO ® foam film lamellae by increasing pH is classically explained by the electrostatic repulsive interaction of the double layer in foam film. In other hand, the addition of dodecanol (DOH) on SDS solution seems to have no effect on foam regime and lamellae stability except for high DOH concentration where the foam film shape becomes double bump. The behaviour difference between AKYPO ® and SDS lays on the lamellae shape and stability domain. While SDS lamellae stay unchanged with increasing pressure ratio between the gas and the liquid, AKYPO ® lamellae curvature radius increases which could be related to surfactants solubilities and structure. These results pointed out the relevance of solution physicochemical parameters on foam stability and flowing and help the understanding of flowing foam in EOR context.

Published
2016
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8. Specific Salt and pH Effects on Foam Film of a pH Sensitive Surfactant

Author

Pierre Bauduin, Olivier Diat, Cyril Micheau, Sylvain Faure, Ions aux Interfaces Actives (L2IA), 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), Service des Procedés de Décontamination et d'Enrobage des Déchets (SPDE), 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
Carboxylic acid, Inorganic chemistry, flotation, Salt (chemistry), 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Ion, Divalent, Surface-Active Agents, Pulmonary surfactant, Electrochemistry, Zeta potential, Surface Tension, ion extraction, General Materials Science, Spectroscopy, Double layer (biology), chemistry.chemical_classification, SANS, Surfaces and Interfaces, Hydrogen-Ion Concentration, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Small-angle neutron scattering, 0104 chemical sciences, chemistry, Salts, foam, 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience; Film thickness of foams made of a pH sensitive surfactant with ion complexing properties, nonaoxyethylene oleylether carboxylic acid (AKYPO® RO 90 VG), has been determined in situ by small angle neutron scattering (SANS). The effect on the film thickness of pH variation and salt addition of nitrate salts with different cation valency (Na+, Ca2+ or Nd3+) was investigated and discussed in terms of the influent parameters stabilizing the foam such as surface properties and electrostatic effects. On one hand zeta potential was measured on the bulk micellar solutions in order to obtain information on surface charge. On the other hand tensiometry measurement at the water-air interface informed on static and dynamic properties of the surfactant such as the critical micellar concentration, area per surfactant head group and diffusion coefficient of the surfactant.It was observed that reducing the surface charge, i.e. by increasing the amount of neutral form of the surfactant over the charged carboxylate form, either by changing pH from high to low values or by adding a complexing multi-valent ion results in an increase in the film thickness. Accordingly, the variations in the surface coverage of the surfactant as well as in the cmc values indicate that the surfactant has a more pronounced surface activity in acidic condition or in the presence of a trivalent cation. Consequently the film thickness results in a subtle interplay between screening of the double layer in foam films (tranverse interaction) increased with ionic strength and cohesive forces between surfactants at the interface (lateral interaction) increased by surface ion complexation or surfactant protonation. The pH and specific salt effects revealed that foams produced by nonaoxyethylene oleylether carboxylic acid are of interest in the potential use of this surfactant in ion separation process based on foam such as ion flotation of multi-valent metal ions.

Published
2013
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9. Evaluation of ion separation coefficients by foam flotation using a carboxylate surfactant

Author

Cyril Micheau, Pierre Bauduin, Andreas Schneider, Luc Girard, Ions aux Interfaces Actives (L2IA), 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, Chemistry, Inorganic chemistry, Analytical chemistry, Micelle, Ion, chemistry.chemical_compound, Colloid and Surface Chemistry, Pulmonary surfactant, Zeta potential, [CHIM]Chemical Sciences, Qualitative inorganic analysis, Carboxylate, Selectivity, ComputingMilieux_MISCELLANEOUS
Abstract

Separation of metal cations of different charges, Na+, Li+, Ca2+, Sr2+, Cu2+, Nd3+ and Eu3+ was investigated through ion foam flotation using a pH sensitive surfactant, nonaoxyethylene oleyl ether carboxylic acid. We propose here a method to evaluate ion selectivity coefficients using mass and volume balances. This method yields selectivity coefficients in agreement with those obtained with the classical slope method. The ion selectivity obtained by the flotation experiments was found to correlate well with the apparent charge of the surfactant micelles (zeta potential values) in the presence of different salts and is therefore not influenced by the surface curvature. Consequently the ion specificity order has been established according to the surfactant–ion affinity at the air–water and micelle–water interfaces as Na+

Published
2015
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