165 results on '"Sebastiano Garroni"'
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2. Toxicological assessment of pristine and degraded forms of graphene functionalized with MnOx nanoparticles using human in vitro models representing different exposure routes
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Natalia Fernández-Pampín, Juan José González Plaza, Alejandra García-Gómez, Elisa Peña, Sebastiano Garroni, Matteo Poddighe, Carlos Rumbo, Rocío Barros, Sonia Martel-Martín, Santiago Aparicio, and Juan Antonio Tamayo-Ramos
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Medicine ,Science - Abstract
Abstract The development of novel advanced nanomaterials (NMs) with outstanding characteristics for their use in distinct applications needs to be accompanied by the generation of knowledge on their potential toxicological impact, in particular, that derived from different occupational risk exposure routes, such as inhalation, ingestion, and skin contact. The harmful effects of novel graphene-metal oxide composites on human health are not well understood, many toxicological properties have not been investigated yet. The present study has evaluated several toxicological effects associated with graphene decorated with manganese oxide nanoparticles (GNA15), in a comparative assessment with those induced by simple graphene (G2), on human models representing inhalation (A549 cell line), ingestion (HT29 cell line) and dermal routes (3D reconstructed skin). Pristine and degraded forms of these NMs were included in the study, showing to have different physicochemical and toxicological properties. The degraded version of GNA15 (GNA15d) and G2 (G2d) exhibited clear structural differences with their pristine counterparts, as well as a higher release of metal ions. The viability of respiratory and gastrointestinal models was reduced in a dose-dependent manner in the presence of both GNA15 and G2 pristine and degraded forms. Besides this, all NMs induced the production of reactive oxygen species (ROS) in both models. However, the degraded forms showed to induce a higher cytotoxicity effect. In addition, we found that none of the materials produced irritant effects on 3D reconstructed skin when present in aqueous suspensions. These results provide novel insights into the potentially harmful effects of novel multicomponent NMs in a comprehensive manner. Furthermore, the integrity of the NMs can play a role in their toxicity, which can vary depending on their composition and the exposure route.
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- 2023
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3. Mechanochemical effects underlying the mechanically activated catalytic hydrogenation of carbon monoxide
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Maria Carta, Anna Laura Sanna, Andrea Porcheddu, Sebastiano Garroni, and Francesco Delogu
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Medicine ,Science - Abstract
Abstract In this work, we highlight and measure the intensity of mechanochemical effects at work in the hydrogenation of carbon monoxide by comparing the activity of a supported Co–Fe catalyst subjected, respectively, to ball milling and simple powder agitation. Paying due regard to the discontinuous nature of ball milling, we show that mechanochemical hydrogenation proceeds at significantly higher rate and disclose its connection with individual impacts. Experimental evidence suggests that the enhanced catalytic activity we observe can be ascribed to local processes affecting the amount of powder that gets involved in individual impacts.
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- 2023
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4. High-Entropy Diborides—Silicon Carbide Composites by Reactive and Non-Reactive Spark Plasma Sintering: A Comparative Study
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Ekaterina Pakhomova, Giacomo Cao, Roberto Orrù, Sebastiano Garroni, Paolo Ferro, and Roberta Licheri
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high-entropy borides ,silicon carbide ,spark plasma sintering ,self-propagating high-temperature synthesis ,resistance to oxidation ,fracture toughness ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The reactive spark plasma sintering (R-SPS) method was compared in this work with the two-step SHS–SPS route, based on the combination of the self-propagating high-temperature synthesis (SHS) with the SPS process, for the fabrication of dense (Hf0.2Mo0.2Ti0.2Ta0.2Nb0.2)B2–SiC and (Hf0.2Mo0.2Ti0.2Ta0.2Zr0.2)B2–SiC ceramics. A multiphase and inhomogeneous product, containing various borides, was obtained at 2000 °C/20 min by R-SPS from transition metals, B4C, and Si. In contrast, if the same precursors were first reacted by SHS and then processed by SPS under the optimized condition of 1800 °C/20 min, the desired ceramics were successfully attained. The resulting sintered samples possessed relative densities above 97% and displayed uniform microstructures with residual oxide content 1/2) as the SPS conditions became more severe. SiC addition was found to inhibit the volatilization of metal oxides like MoO3 formed during oxidation experiments, thus avoiding mass loss in the ceramics. The benefits above also likely took advantage of the fact that the two composite constituents were synthesized in parallel, according to the SHS–SPS approach, rather than being produced separately and combined subsequently, so that strong interfaces between them were formed.
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- 2024
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5. Chemical effects induced by the mechanical processing of granite powder
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Anna Laura Sanna, Maria Carta, Giorgio Pia, Sebastiano Garroni, Andrea Porcheddu, and Francesco Delogu
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Medicine ,Science - Abstract
Abstract Starting from 1970s, the use of mechanical forces to induce chemical transformations has radically changed vast areas of metallurgy and materials science. More recently, mechanochemistry has expanded to core sectors of chemistry, showing the promise to deeply innovate chemical industry while enhancing its sustainability and competitiveness. We are still far, however, from unveiling the full potential of mechanical activation. This study marks a step forward in this direction focusing on the chemical effects induced on the surrounding gaseous phase by the mechanical processing of granite. We show that fracturing granite blocks in oxygen can result in the generation of ozone. The refinement of coarse granite particles and the friction between fine ones are also effective in this regard. Combining experimental evidence related to the crushing of large granite samples by uniaxial compression and the ball milling of coarse and fine granite powders, we develop a model that relates mechanochemical ozone generation to the surface area effectively affected by fracture and frictional events taking place during individual impacts. We also extend the investigation to gaseous phases involving methane, oxygen, benzene and water, revealing that chemical transformations occur as well.
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- 2022
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6. Comparative Evaluation of Graphene Nanostructures in GERS Platforms for Pesticide Detection
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Swapneel Thakkar, Lidia De Luca, Silvia Gaspa, Alberto Mariani, Sebastiano Garroni, Antonio Iacomini, Luigi Stagi, Plinio Innocenzi, and Luca Malfatti
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Chemistry ,QD1-999 - Published
- 2022
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7. Fabrication and Characterization of Quinary High Entropy-Ultra-High Temperature Diborides
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Simone Barbarossa, Roberto Orrù, Valeria Cannillo, Antonio Iacomini, Sebastiano Garroni, Massimiliano Murgia, and Giacomo Cao
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high entropy metal borides ,spark plasma sintering ,self-propagating high-temperature synthesis ,mechanical properties ,Technology ,Chemical technology ,TP1-1185 - Abstract
Due to their inherent chemical complexity and their refractory nature, the obtainment of highly dense and single-phase high entropy (HE) diborides represents a very hard target to achieve. In this framework, homogeneous (Hf0.2Nb0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, and (Hf0.2Zr0.2Nb0.2Mo0.2Ti0.2)B2 ceramics with high relative densities (97.4, 96.5, and 98.2%, respectively) were successfully produced by spark plasma sintering (SPS) using powders prepared by self-propagating high-temperature synthesis (SHS). Although the latter technique did not lead to the complete conversion of initial precursors into the prescribed HE phases, such a goal was fully reached after SPS (1950 °C/20 min/20 MPa). The three HE products showed similar and, in some cases, even better mechanical properties compared to ceramics with the same nominal composition attained using alternative processing methods. Superior Vickers hardness and elastic modulus values were found for the (Hf0.2Nb0.2Ta0.2Mo0.2Ti0.2)B2 and the (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 systems, i.e., 28.1 GPa/538.5 GPa and 28.08 GPa/498.1 GPa, respectively, in spite of the correspondingly higher residual porosities (1.2 and 2.2 vol.%, respectively). In contrast, the third ceramic, not containing tantalum, displayed lower values of these two properties (25.1 GPa/404.5 GPa). However, the corresponding fracture toughness (8.84 MPa m1/2) was relatively higher. This fact can be likely ascribed to the smaller residual porosity (0.3 vol.%) of the sintered material.
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- 2021
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8. Processing, phase evolution and electrical properties of 'lead free' KNN–BF–CuO eco-piezoceramic from mechanochemically activated precursors
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Antonio Iacomini, Sebastiano Garroni, Gabriele Mulas, Stefano Enzo, Luca Cappai, Marzia Mureddu, Costantino Cau, Álvaro García, and Lorena Pardo
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Lead free piezoceramics ,Ceramic processing ,Sintering aid ,Sodium potassium niobate ,Bismuth ferrite ,Mechanochemical activation ,Clay industries. Ceramics. Glass ,TP785-869 - Abstract
“Lead free” piezoceramics 0.99K0.5Na0.5NbO3-0.01BiFeO3 (KNN–BF) with increasing amount of CuO (0, 0.5, 1 wt.%) were prepared through a scalable combination of High Energy Ball Milling, calcination at 900 °C and air sintering. The effect of CuO on the sintering behaviour and electrical properties of KNN–BF was investigated. The compositions examined show high-density values (>95% of TD) at their optimized sintering temperatures. Small addition of CuO (0.5 wt.%) causes an increase in the size of grains, however an excess of CuO (1 wt.%) inhibits the growth of grains due to the excess of liquid phase. The KNN–BF composition shows promising electrical properties (d33 = 150 pC/N; kp = 42%; Qm = 150) which are mainly related to the high density achieved and to the orthorhombic-tetragonal symmetry coexistence. The addition of 0.5 wt.% of CuO causes an increase in the quality factors (Qm = 235; Q(d31) = 207).
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- 2022
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9. Solid State Processing of BCZT Piezoceramics Using Ultra Low Synthesis and Sintering Temperatures
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Marzia Mureddu, José F. Bartolomé, Sonia Lopez-Esteban, Maria Dore, Stefano Enzo, Álvaro García, Sebastiano Garroni, and Lorena Pardo
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barium calcium zirconate titanate ,attrition milling ,ceramics ,piezoelectrics ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Lead-free (Ba0.92Ca0.08) (Ti0.95 Zr0.05) O3 (BCZT) ceramics were prepared by a solid-state route (SSR) using ultra-low synthesis (700 °C/30 min and 700 °C/2 h) and sintering temperatures (from 1150 °C to 1280 °C), due to prior activation and homogenization by attrition milling of the starting high purity raw materials for 6 h before the synthesis and of the calcined powders for 3 h before the sintering. The comparison of the thermal analysis of the mixture of the starting raw materials and the same mixture after 6 h attrition milling allowed to evidence the mechanisms of activation, resulting in a significant decrease of the perovskite formation temperature (from 854 °C down to 582 °C). The secondary phases that limit the functional properties of the ceramic and their evolution with the sintering conditions were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), which allowed the design of a two-step sintering method to eliminate them. A pure tetragonal BCZT perovskite phase (P4mm, c/a = 1.004) and homogeneous ceramic microstructure was obtained for synthesis at 700 °C for 2 h and sintering with the use of a two-step sintering treatment (900 °C for 3 h and 1280 °C for 6 h). The best electromechanical properties achieved were d33 = 455 pC/N, kp = 35%, Qm = 155.
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- 2023
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10. Harnessing Molecular Fluorophores in the Carbon Dots Matrix: The Case of Safranin O
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Manuela Meloni, Luigi Stagi, Davide Sanna, Sebastiano Garroni, Laura Calvillo, Angela Terracina, Marco Cannas, Fabrizio Messina, Carlo Maria Carbonaro, Plinio Innocenzi, and Luca Malfatti
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carbon dots ,safranin ,phosphors ,nanoparticles ,Chemistry ,QD1-999 - Abstract
The origin of fluorescence in carbon dots (C-dots) is still a puzzling phenomenon. The emission is, in most of the cases, due to molecular fluorophores formed in situ during the synthesis. The carbonization during C-dots processing does not allow, however, a fine control of the properties and makes finding the source of the fluorescence a challenging task. In this work, we present a strategy to embed a pre-formed fluorescent molecule, safranin O dye, into an amorphous carbonaceous dot obtained by citric acid carbonization. The dye is introduced in the melted solution of citric acid and after pyrolysis remains incorporated in a carbonaceous matrix to form red-emitting C-dots that are strongly resistant to photobleaching. Embedding dyes in amorphous C-dots represents an alternative method to optimize the emission in the whole visible spectrum.
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- 2022
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11. Improving the Photocatalytic Activity of Mesoporous Titania Films through the Formation of WS2/TiO2 Nano-Heterostructures
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Junkai Ren, Luigi Stagi, Luca Malfatti, Valentina Paolucci, Carlo Cantalini, Sebastiano Garroni, Marzia Mureddu, and Plinio Innocenzi
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tungsten disulfide ,titania ,heterostructure ,photocatalysis ,mesoporous films ,Chemistry ,QD1-999 - Abstract
Heterostructures formed by anatase nanotitania and bidimensional semiconducting materials are expected to become the next-generation photocatalytic materials with an extended operating range and higher performances. The capability of fabricating optically transparent photocatalytic thin films is also a highly demanded technological issue, and increasing the performances of such devices would significantly impact several applications, from self-cleaning surfaces to photovoltaic systems. To improve the performances of such devices, WS2/TiO2 heterostructures obtained by incorporating two-dimensional transition metal dichalcogenides layers into titania mesoporous ordered thin films have been fabricated. The self-assembly process has been carefully controlled to avoid disruption of the order during film fabrication. WS2 nanosheets of different sizes have been exfoliated by sonication and incorporated in the mesoporous films via one-pot processing. The WS2 nanosheets result as well-dispersed within the titania anatase mesoporous film that retains a mesoporous ordered structure. An enhanced photocatalytic response due to an interparticle electron transfer effect has been observed. The structural characterization of the heterostructure has revealed a tight interplay between the matrix and nanosheets rather than a simple additive co-catalyst effect.
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- 2022
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12. Functionalization of Screen-Printed Sensors with a High Reactivity Carbonaceous Material for Ascorbic Acid Detection in Fresh-Cut Fruit with Low Vitamin C Content
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Ylenia Spissu, Antonio Barberis, Gianfranco Bazzu, Guy D’hallewin, Gaia Rocchitta, Pier Andrea Serra, Salvatore Marceddu, Claudia Vineis, Sebastiano Garroni, and Nicola Culeddu
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graphene ,screen-printed sensors ,multi-walled carbon nanotubes ,ascorbic acid ,LOD ,diffusion rate ,Biochemistry ,QD415-436 - Abstract
In this study, carbon screen-printed sensors (C-SPEs) were functionalized with a high reactivity carbonaceous material (HRCM) to measure the ascorbic acid (AA) concentration in fresh-cut fruit (i.e., watermelon and apple) with a low content of vitamin C. HRCM and the functionalized working electrodes (WEs) were characterized by SEM and TEM. The increases in the electroactive area and in the diffusion of AA molecules towards the WE surface were evaluated by cyclic voltammetry (CV) and chronoamperometry. The performance of HRCM-SPEs were evaluated by CV and constant potential amperometry compared with the non-functionalized C-SPEs and MW-SPEs nanostructured with multi-walled carbon nanotubes. The results indicated that SPEs functionalized with 5 mg/mL of HRCM and 10 mg/mL of MWCNTs had the best performances. HRCM and MWCNTs increased the electroactive area by 1.2 and 1.4 times, respectively, whereas, after functionalization, the AA diffusion rate towards the electrode surface increased by an order of 10. The calibration slopes of HRCM and MWCNTs improved from 1.9 to 3.7 times, thus reducing the LOD of C-SPE from 0.55 to 0.15 and 0.28 μM, respectively. Finally, the functionalization of the SPEs proved to be indispensable for determining the AA concentration in the watermelon and apple samples.
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- 2021
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13. Variation of Used Vegetable Oils’ Composition upon Treatment with Algerian Clays
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Abdelhak Serouri, Zoubida Taleb, Alberto Mannu, Sebastiano Garroni, Nina Senes, Safia Taleb, Sara Brini, and Sabrine Kawther Abdoun
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FT-IR ,waste vegetable oils ,vegetable oils recycling ,bentonite ,Environmental sciences ,GE1-350 - Abstract
The treatment of used vegetable oils (UVOs) with clays represents a pivotal step in their industrial recycling process as well as one of the most challenging topics for researchers. In particular, cheap, effective, and sustainable powders need to be explored in order to develop new processes which produce beneficial results in relation to economic and environmental aspects. In this context, five samples within commercial and waste vegetable oils were treated with two sodium- and calcium-based bentonites employing a low oil/bentonite ratio (0.15 wt%). The outcomes of the processes were monitored by FT-IR spectroscopy and compared with the data relative to the parent commercial edible oil. In particular, treatment of FT-IR data by multivariate statistical analysis allowed us to determine a chemical fingerprint characteristic of each sample. Important relationships between the overall chemical composition and the specific clay employed and the treatment time (2 or 4 h) were highlighted. Finally, N2 physisorption, TEM microscopy, and FT-IR analyses of the more efficient Na bentonite allowed us to characterize the material and thus to furnish all the information needed to set-up a general protocol for the partial regeneration of waste vegetable oil destined for further processing.
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- 2021
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14. Processing Optimization and Toxicological Evaluation of 'Lead-Free' Piezoceramics: A KNN-Based Case Study
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Antonio Iacomini, Juan Antonio Tamayo-Ramos, Carlos Rumbo, Irem Urgen, Marzia Mureddu, Gabriele Mulas, Stefano Enzo, and Sebastiano Garroni
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lead-free piezoceramics ,sodium potassium niobate ,processing ,toxicity assays ,X-ray diffraction ,mechanochemistry ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Due to the ever-increasing limitations of the use of lead-based materials, the manufacturing of lead-free piezoceramics with competitive piezoelectric properties and established nontoxicity is considered a priority for the scientific and industrial community. In this work, a lead-free system based on sodium potassium niobate (KNN), opportunely modified with MgNb2O6 (MN), was prepared through a combination of a mechanochemical activation method and air sintering, and its toxicity was evaluated. The effect of the mechanical processing on the microstructure refinement of the processed powders was established by X-ray diffraction and the average crystallite size content of the Nb2O5 species was evaluated. The experimental evidence was rationalized using a phenomenological model which permitted us to obtain the amount of powder processed at each collision and to optimize the activation step of the pre-calcined reagents. This influenced the final density and piezoresponse of the as-sintered pellets, which showed optimal properties compared with other KNN systems. Their toxicological potential was evaluated through exposure experiments to the pulverized KNN-based pellets, employing two widely used human and environmental cellular models. The in vitro assays proved, under the selected conditions, the absence of cytotoxicity of KNN-bases systems here studied.
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- 2021
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15. CO2 Hydrogenation Induced by Mechanochemical Activation of Olivine With Water Under CO2 Atmosphere
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Valeria Farina, Nadia S. Gamba, Fabiana Gennari, Sebastiano Garroni, Francesco Torre, Alessandro Taras, Stefano Enzo, and Gabriele Mulas
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CO2 utilization ,olivine ,methane ,mechanochemical activation ,hydrogen ,General Works - Abstract
A study on the mechanochemical activation of the olivine in presence of H2O and under CO2 atmosphere have been approached, focusing both on the structural nature of the transformation and the conversion of CO2 to methane and light hydrocarbons. The mechanochemical process was carried out by high energy laboratory mills, with milling vials properly modified in order to be used as batch reactors. Chemical reactivity and reaction rates were investigated under different experimental conditions, evidencing increased performance with respect to the thermally activated process reported in literature. Mechanical treatment induced H2O and olivine activation, with consequent release of molecular H2 which, in turn, allowed hydrogenation of activated CO2. This last reaction also led, through a competitive process, to the precipitation of carbonate phases, whose composition and structural features were dependent of the CO2/H2O ratio.
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- 2019
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16. A Simple Ball Milling and Thermal Oxidation Method for Synthesis of ZnO Nanowires Decorated with Cubic ZnO2 Nanoparticles
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Antonio Rinaldi, Marialilia Pea, Andrea Notargiacomo, Eloisa Ferrone, Sebastiano Garroni, Luciano Pilloni, and Rodolfo Araneo
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ZnO nanowires ,Zn powders ,ball milling ,thermal oxidation ,core-shell nanowires ,Chemistry ,QD1-999 - Abstract
In this work, we propose the synthesis of ZnO nanostructures through the thermal oxidation of ball-milled powders with the introduction of Mg and Sn doping species at the preliminary step of milling. We investigate the advantages and challenges of this two steps process for the production and fabrication of highly crystalline ZnO nanowires. This simple method allows us to fabricate ZnO nanowires with a higher quality core crystal at a much lower temperature and for a shorter processing time than the state-of-the-art, and decorated with by ZnO2 nanoparticles as determined via TEM analysis. The main findings will show that the crystalline core of the nanowires is of hexagonal ZnO while the nanoparticles on the surface are ZnO2 cubic type. Generally, the method proves to be suitable for applications that require a high surface-to-volume ratio, for example, catalysis phenomena, in which the presence of zinc oxides species can play an important role.
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- 2021
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17. Ammonium Salts Catalyzed Acetalization Reactions in Green Ethereal Solvents
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Ugo Azzena, Massimo Carraro, Martina Corrias, Rosella Crisafulli, Lidia De Luca, Silvia Gaspa, Luca Nuvoli, Salvatore Pintus, Luisa Pisano, Riccardo Polese, Michela Sanna, Giuseppe Satta, Nina Senes, Luigi Urtis, and Sebastiano Garroni
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heterogeneous catalysis ,green solvents ,acetals ,ammonium salts ,characterization of heterogeneous catalysts ,Chemical technology ,TP1-1185 ,Chemistry ,QD1-999 - Abstract
Cyclopentyl methyl ether and 2-methyltetrahydrofuran, low impact ethereal solvents forming a positive azeotrope with water, were successfully employed as solvents in the synthesis of a variety of acetals carried out under Dean–Stark conditions in the presence of heterogeneous acidic catalysts. Under these conditions, ammonium salts, either as such or supported on SiO2, performed better or equally well than widely employed homogeneous and heterogeneous acidic catalysts such as p-toluenesulfonic acid, Amberlyst 15®, or Montmorillonite K10. Several examples highlight the advantage of tuning the relative acidities of ammonium salts by appropriately selecting the counterion. Within one of these examples, our protocol clearly outweighs the classic p-toluenesulfonic acid/toluene protocol in terms of chemoselectivity. Silica-supported catalysts were characterized by SEM, TEM, and FTIR spectroscopies, as well as by N2 physisorption. Such a characterization reveals an even distribution of ammonium salts on silica, thus confirming the formation of expected catalytic supports.
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- 2020
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18. Solvent-Free Mechanochemical Approach towards Thiospinel MgCr2S4 as a Potential Electrode for Post-Lithium Ion Batteries
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Laura Caggiu, Stefano Enzo, Lorenzo Stievano, Romain Berthelot, Claudio Gerbaldi, Marisa Falco, Sebastiano Garroni, and Gabriele Mulas
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thiospinel ,MgCr2S4 ,self-sustaining reaction ,mechanochemistry ,post-lithium battery ,multivalent battery cathode ,Production of electric energy or power. Powerplants. Central stations ,TK1001-1841 ,Industrial electrochemistry ,TP250-261 - Abstract
Several new compounds, with desirable properties of ion mobility and working voltage, have been recently proposed using a density functional theory (DFT) computational approach as potential electrode materials for beyond-lithium battery systems. After evaluation of the ‘energy above hull’, thiospinel MgCr2S4 has been suggested as interesting multivalent battery cathode candidate, even though the synthesis of its exact stoichiometry poses serious challenges. In this work, MgCr2S4 is prepared using an innovative mechanochemical route starting from magnesium or magnesium hydride, chromium, and sulfur powders. The progress of such mechanically induced reaction as a function of processing time is carefully monitored by XRD with Rietveld refinement, evidencing the occurrence of a mechanically induced self-propagating reaction (MSR). The effect of parameters associated with the milling apparatus (impact energy) on the products composition are also investigated. To our knowledge, this work represents the first report of the scalable and simple mechanical alloying synthesis of thiospinel MgCr2S4 (space group Fd-3 m, a = 10.09 Å) and opens up interesting possibilities for the exploitation of such material in next-generation post-lithium batteries.
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- 2020
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19. Study of the Effects Induced by Ball Milling Treatment on Different Types of Hydrocolloids in a Corn Starch–Rice Flour System
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Luca Nuvoli, Paola Conte, Sebastiano Garroni, Valeria Farina, Antonio Piga, and Costantino Fadda
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ball milling ,hydrocolloids ,starch–flour system ,X-ray diffraction ,pasting profile ,viscoelastic properties ,Chemical technology ,TP1-1185 - Abstract
The effects of ball milling treatment on both the structure and properties of guar gum (GG), tara gum (TG), and methylcellulose (MC) were analyzed prior to assessing their potential interactions with starch components when they are used alone or in blends in a corn starch–rice flour system. X-ray diffraction profiles showed that the ball milling caused a reduction in the crystallin domain and, in turn, a diminished viscosity of the GG aqueous solutions. Despite an increase in its viscosity properties, effects on TG were minimal, while the milled MC exhibited reduced crystallinity, but similar viscosity. When both milled and un-milled hydrocolloids were individually added to the starch–flour system, the pasting properties of the resulting mixtures seemed to be affected by the type of hydrocolloid added rather than the structural changes induced by the treatment. All hydrocolloids increased the peak viscosity of the binary blends (especially pure GG), but only milled and un-milled MC showed values of setback and final viscosity similar to those of the individual starch. Ball milling seemed to be more effective when two combined hydrocolloids (milled GG and MC) were simultaneously used. No significant differences were observed in the viscoelastic properties of the blends, except for un-milled GG/starch, milled TG/starch, and milled MC/milled TG/starch gels.
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- 2020
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20. Enhanced Stability of Li-RHC Embedded in an Adaptive TPX™ Polymer Scaffold
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Thi Thu Le, Claudio Pistidda, Clarissa Abetz, Prokopios Georgopanos, Sebastiano Garroni, Giovanni Capurso, Chiara Milanese, Julián Puszkiel, Martin Dornheim, Volker Abetz, and Thomas Klassen
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confinement ,confined complex hydrides ,carbon-based polymer ,hydrogen storage ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
In this work, the possibility of creating a polymer-based adaptive scaffold for improving the hydrogen storage properties of the system 2LiH+MgB2+7.5(3TiCl3·AlCl3) was studied. Because of its chemical stability toward the hydrogen storage material, poly(4-methyl-1-pentene) or in-short TPXTM was chosen as the candidate for the scaffolding structure. The composite system was obtained after ball milling of 2LiH+MgB2+7.5(3TiCl3·AlCl3) and a solution of TPXTM in cyclohexane. The investigations carried out over the span of ten hydrogenation/de-hydrogenation cycles indicate that the material containing TPXTM possesses a higher degree of hydrogen storage stability.
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- 2020
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21. Mesoporous Titania Powders: The Role of Precursors, Ligand Addition and Calcination Rate on Their Morphology, Crystalline Structure and Photocatalytic Activity
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Elisabetta Masolo, Manuela Meloni, Sebastiano Garroni, Gabriele Mulas, Stefano Enzo, Maria Dolors Baró, Emma Rossinyol, Agnieszka Rzeszutek, Iris Herrmann-Geppert, and Maria Pilo
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titania ,EISA method ,powders ,photocatalysis ,water splitting ,Chemistry ,QD1-999 - Abstract
We evaluate the influence of the use of different titania precursors, calcination rate, and ligand addition on the morphology, texture and phase content of synthesized mesoporous titania samples, parameters which, in turn, can play a key role in titania photocatalytic performances. The powders, obtained through the evaporation-induced self-assembly method, are characterized by means of ex situ X-Ray Powder Diffraction (XRPD) measurements, N2 physisorption isotherms and transmission electron microscopy. The precursors are selected basing on two different approaches: the acid-base pair, using TiCl4 and Ti(OBu)4, and a more classic route with Ti(OiPr)4 and HCl. For both precursors, different specimens were prepared by resorting to different calcination rates and with and without the addition of acetylacetone, that creates coordinated species with lower hydrolysis rates, and with different calcination rates. Each sample was employed as photoanode and tested in the water splitting reaction by recording I-V curves and comparing the results with commercial P25 powders. The complex data framework suggests that a narrow pore size distribution, due to the use of acetylacetone, plays a major role in the photoactivity, leading to a current density value higher than that of P25.
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- 2014
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22. Efficient Synthesis of Alkali Borohydrides from Mechanochemical Reduction of Borates Using Magnesium–Aluminum-Based Waste
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Thi Thu Le, Claudio Pistidda, Julián Puszkiel, Chiara Milanese, Sebastiano Garroni, Thomas Emmler, Giovanni Capurso, Gökhan Gizer, Thomas Klassen, and Martin Dornheim
- Subjects
alkali borohydrides ,mg–al waste ,ball milling ,high conversion yield ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Lithium borohydride (LiBH4) and sodium borohydride (NaBH4) were synthesized via mechanical milling of LiBO2, and NaBO2 with Mg−Al-based waste under controlled gaseous atmosphere conditions. Following this approach, the results herein presented indicate that LiBH4 and NaBH4 can be formed with a high conversion yield starting from the anhydrous borates under 70 bar H2. Interestingly, NaBH4 can also be obtained with a high conversion yield by milling NaBO2·4H2O and Mg−Al-based waste under an argon atmosphere. Under optimized molar ratios of the starting materials and milling parameters, NaBH4 and LiBH4 were obtained with conversion ratios higher than 99.5%. Based on the collected experimental results, the influence of the milling energy and the correlation with the final yields were also discussed.
- Published
- 2019
- Full Text
- View/download PDF
23. Variation of the Chemical Composition of Waste Cooking Oils upon Bentonite Filtration
- Author
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Alberto Mannu, Gina Vlahopoulou, Paolo Urgeghe, Monica Ferro, Alessandra Del Caro, Alessandro Taras, Sebastiano Garroni, Jonathan P. Rourke, Roberto Cabizza, and Giacomo L. Petretto
- Subjects
waste cooking oil ,nuclear magnetic resonance ,headspace solid-phase microextraction ,thermogravimetry ,principal components analysis ,X-ray diffraction ,Science - Abstract
The chemical composition and the color of samples of waste cooking oils (WCOs) were determined prior to and after filtration on two different pads of bentonite differing in particle size. The volatile fraction was monitored by headspace solid-phase microextraction (HS-SPME) coupled with gas-chromatography, while the variation of the composition of the main components was analyzed by 1H NMR. Both techniques allowed the detection of some decomposition products, such as polymers, terpenes, and derivatives of the Maillard process. The analysis of the chemical composition prior to and after bentonite treatment revealed a tendency for the clays to retain specific chemical groups (such as carboxylic acids or double bonds), independent of their particle size. A pair comparison test was conducted in order to detect the sensory differences of the intensity of aroma between the WCO treated with the two different bentonites. In addition, characterization of the bentonite by means of powder X-ray diffraction (XRD) and thermogravimetric measurements (TG) was performed.
- Published
- 2019
- Full Text
- View/download PDF
24. Solid State Hydrogen Storage in Alanates and Alanate-Based Compounds: A Review
- Author
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Chiara Milanese, Sebastiano Garroni, Fabiana Gennari, Amedeo Marini, Thomas Klassen, Martin Dornheim, and Claudio Pistidda
- Subjects
alanates ,metal aluminum hydrides ,solid state hydrogen storage ,complex hydrides ,reactive hydride composite ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The safest way to store hydrogen is in solid form, physically entrapped in molecular form in highly porous materials, or chemically bound in atomic form in hydrides. Among the different families of these compounds, alkaline and alkaline earth metals alumino-hydrides (alanates) have been regarded as promising storing media and have been extensively studied since 1997, when Bogdanovic and Schwickardi reported that Ti-doped sodium alanate could be reversibly dehydrogenated under moderate conditions. In this review, the preparative methods; the crystal structure; the physico-chemical and hydrogen absorption-desorption properties of the alanates of Li, Na, K, Ca, Mg, Y, Eu, and Sr; and of some of the most interesting multi-cation alanates will be summarized and discussed. The most promising alanate-based reactive hydride composite (RHC) systems developed in the last few years will also be described and commented on concerning their hydrogen absorption and desorption performance.
- Published
- 2018
- Full Text
- View/download PDF
25. Recent Progress and New Perspectives on Metal Amide and Imide Systems for Solid-State Hydrogen Storage
- Author
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Sebastiano Garroni, Antonio Santoru, Hujun Cao, Martin Dornheim, Thomas Klassen, Chiara Milanese, Fabiana Gennari, and Claudio Pistidda
- Subjects
hydrogen storage materials ,metal amides ,thermodynamics and kinetics ,Technology - Abstract
Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Although in the last 15 years a large variety of material systems have been identified as possible candidates for storing hydrogen, further efforts have to be made in the development of systems which meet the strict targets of the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and U.S. Department of Energy (DOE). Recent projections indicate that a system possessing: (i) an ideal enthalpy in the range of 20–50 kJ/mol H2, to use the heat produced by PEM fuel cell for providing the energy necessary for desorption; (ii) a gravimetric hydrogen density of 5 wt. % H2 and (iii) fast sorption kinetics below 110 °C is strongly recommended. Among the known hydrogen storage materials, amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however, some barriers still have to be overcome before considering this class of material mature for real applications. In this review, the most relevant progresses made in the recent years as well as the kinetic and thermodynamic properties, experimentally measured for the most promising systems, are reported and properly discussed.
- Published
- 2018
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26. Tetrahydroborates: Development and Potential as Hydrogen Storage Medium
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Julián Puszkiel, Sebastiano Garroni, Chiara Milanese, Fabiana Gennari, Thomas Klassen, Martin Dornheim, and Claudio Pistidda
- Subjects
tetrahydroborates ,synthesis ,decomposition pathways ,tailoring ,solid state hydrogen storage ,Inorganic chemistry ,QD146-197 - Abstract
The use of fossil fuels as an energy supply becomes increasingly problematic from the point of view of both environmental emissions and energy sustainability. As an alternative, hydrogen is widely regarded as a key element for a potential energy solution. However, different from fossil fuels such as oil, gas, and coal, the production of hydrogen requires energy. Alternative and intermittent renewable sources such as solar power, wind power, etc., present multiple advantages for the production of hydrogen. On one hand, the renewable sources contribute to a remarkable reduction of pollutants released to the air. On the other hand, they significantly enhance the sustainability of energy supply. In addition, the storage of energy in form of hydrogen has a huge potential to balance an effective and synergetic utilization of the renewable energy sources. In this regard, hydrogen storage technology presents a key roadblock towards the practical application of hydrogen as “energy carrier”. Among the methods available to store hydrogen, solid-state storage is the most attractive alternative both from the safety and the volumetric energy density points of view. Because of their appealing hydrogen content, complex hydrides and complex hydride-based systems have attracted considerable attention as potential energy vectors for mobile and stationary applications. In this review, the progresses made over the last century on the development in the synthesis and research on the decomposition reactions of homoleptic tetrahydroborates is summarized. Furthermore, theoretical and experimental investigations on the thermodynamic and kinetic tuning of tetrahydroborates for hydrogen storage purposes are herein reviewed.
- Published
- 2017
- Full Text
- View/download PDF
27. Elucidating charge-transfer mechanisms and their effect on the light-induced reactivity of metastable MIL-125(Ti)
- Author
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Pietro, Rassu, Luca, Cappai, Luigi, Stagi, Ruirui, Liu, Stefano, Enzo, Gabriele, Mulas, Sebastiano, Garroni, Luca, Malfatti, Plinio, Innocenzi, Xiaojie, Ma, and Bo, Wang
- Published
- 2024
- Full Text
- View/download PDF
28. Combustion synthesis and spark plasma sintering of apatite-tricalcium phosphate nanocomposites
- Author
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Damiano Angioni, Roberto Orrù, Giacomo Cao, Sebastiano Garroni, Pier Carlo Ricci, and Khachatur V. Manukyan
- Subjects
Process Chemistry and Technology ,Materials Chemistry ,Ceramics and Composites ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Published
- 2023
29. Spark plasma sintering, mechanical and in-vitro behavior of a novel Sr- and Mg-containing bioactive glass for biomedical applications
- Author
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Sebastiano Garroni, Antonio Iacomini, Damiano Angioni, Valeria Cannillo, Giacomo Cao, Devis Bellucci, and Roberto Orru
- Subjects
Materials science ,Bioactive glasses ,Spark plasma sintering ,Nucleation ,Mechanical properties ,In-vitro tests ,Rietveld method ,Grain size ,Amorphous solid ,law.invention ,Chemical engineering ,law ,visual_art ,Bioactive glass ,Vickers hardness test ,Materials Chemistry ,Ceramics and Composites ,visual_art.visual_art_medium ,Ceramic ,Crystallization - Abstract
The so-called BGMS10, a bioactive glass containing 10 mol.% SrO and 10 mol.% MgO, displays a low inclination to crystallize, as confirmed by its high activation energy (538.9 kJ/mol). Such peculiar aspect and the beneficial use of SPS allow for the obtainment of 99.7 % dense and fully amorphous products at 750 °C. The incipient crystallization in the glass is observed when temperature is increased to 850 °C, while 95 wt. % crystallized ceramics are produced at 950 °C. Main crystalline phases are α- and β-CaSiO3, with grain size of 89 and 97 nm, respectively. Glass crystallization is accompanied by Young’s modulus increase from 90.92 to 98.38 GPa. On the other hand, partially crystallized samples (850 °C) exhibit higher Vickers hardness (718.8) compared to fully crystallized ones (619.8), which show lower density (98.6%). In-vitro tests in SBF indicate that the silica-gel film preceding apatite nucleation is mostly formed on the amorphous substrate region.
- Published
- 2022
30. Bioactivity enhancement by a ball milling treatment in novel bioactive glass-hydroxyapatite composites produced by spark plasma sintering
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Damiano Angioni, Roberto Orrù, Giacomo Cao, Sebastiano Garroni, Devis Bellucci, and Valeria Cannillo
- Subjects
Ball milling ,Spark Plasma Sintering (SPS) ,Materials Chemistry ,Ceramics and Composites ,Bioactive glass ,Hydroxyapatite ,Composites - Published
- 2023
31. MgNb 2 O 6 Modified K 0.5 Na 0.5 NbO 3 Eco‐Piezoceramics: Scalable Processing, Structural Distortion and Complex Impedance at Resonance
- Author
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Antonio Iacomini, José F. Bartolomé, Nina Senes, Álvaro López García, Stefano Enzo, Lorena Pardo, Gabriele Mulas, Sebastiano Garroni, and Matteo Poddighe
- Subjects
Materials science ,Scanning electron microscope ,visual_art ,Phase (matter) ,visual_art.visual_art_medium ,Orthorhombic crystal system ,General Chemistry ,Ceramic ,Dielectric ,Composite material ,Microstructure ,Piezoelectricity ,Grain size - Abstract
In this work, piezoceramics of the lead-free composition K0.5 Na0.5 NbO3 with an increasing amount of MgNb2 O6 (0, 0.5, 1, 2 wt.%) were prepared through conventional solid-state synthesis and sintered in air atmosphere at 1100 °C. The effect of magnesium niobate addition on structure, microstructure and piezoelectric properties was evaluated. The ceramics maintain the orthorhombic Amm2 phase for all compositions, while an orthorhombic Pbcm secondary phase was found for increasing the concentration of MgNb2 O6 . Our results show that densification of these ceramics can be significantly improved up to 94.9 % of theoretical density by adding a small amount of magnesium-based oxide (1 wt.%). Scanning electron microscopy morphology of the 1 wt.% system reveals a well-packed structure with homogeneous grain size of ∼2.72 μm. Dielectric and piezoelectric properties become optimal for 0.5-1.0 wt.% of MgNb2 O6 that shows, with respect to the unmodified composition, either higher piezoelectric coefficients, lower anisotropy and relatively low piezoelectric losses (d33 =97 pC N-1 ; d31 =-36.99 pC N-1 and g31 =-14.04×10-3 mV N-1 ; Qp (d31 )=76 and Qp (g31 )=69) or enhanced electromechanical coupling factors (kp =29.06 % and k31 =17.25 %).
- Published
- 2021
32. Boron Nitride–Titania Mesoporous Film Heterostructures
- Author
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Luca Malfatti, Junkai Ren, Sebastiano Garroni, Luigi Stagi, Plinio Innocenzi, and Stefano Enzo
- Subjects
Anatase ,Materials science ,Nucleation ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,law.invention ,chemistry.chemical_compound ,law ,Electrochemistry ,General Materials Science ,Thin film ,Crystallization ,Spectroscopy ,Heterojunction ,Surfaces and Interfaces ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,chemistry ,Chemical engineering ,Boron nitride ,Photocatalysis ,0210 nano-technology ,Mesoporous material - Abstract
The fabrication of optically active heterostructures in the shape of mesostructured thin films is a highly challenging task. It requires an integrated process to allow in one-step incorporating the two-dimensional materials within the mesoporous ordered host without disrupting the pore organization. Hexagonal boron nitride (BN) nanosheets have been successfully introduced into titania mesoporous films using a template-assisted sol–gel synthesis and evaporation-induced self-assembly. Two types of BN sheets have been used, with and without defects, to investigate the role of defects in heterostructure properties. It has been found that the defects increase the ultraviolet radiation A (UVA) absorbance and enhance the photocatalytic response of the film. The BN sheets are optically transparent and do not exhibit any photocatalytic property but contribute to anatase crystallization via heterogeneous nucleation.
- Published
- 2021
33. Fabrication and Characterization of Quinary High Entropy-Ultra-High Temperature Diborides
- Author
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Valeria Cannillo, Sebastiano Garroni, Massimiliano Murgia, Antonio Iacomini, Simone Barbarossa, Roberto Orru, and Giacomo Cao
- Subjects
Materials science ,Self-propagating high-temperature synthesis ,Tantalum ,Spark plasma sintering ,chemistry.chemical_element ,02 engineering and technology ,mechanical properties ,lcsh:Chemical technology ,lcsh:Technology ,01 natural sciences ,Fracture toughness ,0103 physical sciences ,lcsh:TP1-1185 ,Ceramic ,Composite material ,Elastic modulus ,010302 applied physics ,lcsh:T ,Quinary ,General Medicine ,021001 nanoscience & nanotechnology ,self-propagating high-temperature synthesis ,chemistry ,visual_art ,Vickers hardness test ,visual_art.visual_art_medium ,0210 nano-technology ,high entropy metal borides ,spark plasma sintering - Abstract
Due to their inherent chemical complexity and their refractory nature, the obtainment of highly dense and single-phase high entropy (HE) diborides represents a very hard target to achieve. In this framework, homogeneous (Hf0.2Nb0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, and (Hf0.2Zr0.2Nb0.2Mo0.2Ti0.2)B2 ceramics with high relative densities (97.4, 96.5, and 98.2%, respectively) were successfully produced by spark plasma sintering (SPS) using powders prepared by self-propagating high-temperature synthesis (SHS). Although the latter technique did not lead to the complete conversion of initial precursors into the prescribed HE phases, such a goal was fully reached after SPS (1950 °C/20 min/20 MPa). The three HE products showed similar and, in some cases, even better mechanical properties compared to ceramics with the same nominal composition attained using alternative processing methods. Superior Vickers hardness and elastic modulus values were found for the (Hf0.2Nb0.2Ta0.2Mo0.2Ti0.2)B2 and the (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 systems, i.e., 28.1 GPa/538.5 GPa and 28.08 GPa/498.1 GPa, respectively, in spite of the correspondingly higher residual porosities (1.2 and 2.2 vol.%, respectively). In contrast, the third ceramic, not containing tantalum, displayed lower values of these two properties (25.1 GPa/404.5 GPa). However, the corresponding fracture toughness (8.84 MPa m1/2) was relatively higher. This fact can be likely ascribed to the smaller residual porosity (0.3 vol.%) of the sintered material.
- Published
- 2021
34. Unveiling redox mechanism at the iron centers in the mechanochemically activated conversion of CO2 in the presence of olivine
- Author
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Valeria Farina, Maria Domenica Simula, Alessandro Taras, Luca Cappai, Moulay Tahar Sougrati, Gabriele Mulas, Sebastiano Garroni, Stefano Enzo, and Lorenzo Stievano
- Subjects
Mechanics of Materials ,Mechanical Engineering ,General Materials Science - Abstract
The transformation of olivine during the conversion of CO2 to light hydrocarbons activated by mechanochemical treatments at different impact frequencies was studied by a combination of several complementary characterization methods including X-ray diffraction, Raman and 57Fe Mössbauer spectroscopy. Several olivine samples were studied as a function of the milling time, indicating the gradual transformation of FeII-containing olivine into new FeIII-containing weathering products including iron oxides, magnesium iron carbonates and silicates. The results presented here complement those of a previous study on the weathering process of olivine promoted by mechanochemical activation, by demonstrating the role of the redox activity of the iron species during the activation process. These additional spectroscopic results allow us to thoroughly understand the complex weathering mechanism and to correlate it with the efficiency of the CO2 conversion and storage properties of mechanochemically activated olivine.
- Published
- 2022
35. High-entropy transition metal diborides by reactive and non-reactive spark plasma sintering: A comparative investigation
- Author
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Giovanna Tallarita, Roberto Orru, Roberta Licheri, Sebastiano Garroni, Simone Barbarossa, and Giacomo Cao
- Subjects
Materials science ,Self-propagating high-temperature synthesis ,Spark plasma sintering ,Borides ,02 engineering and technology ,Combustion ,01 natural sciences ,Chemical synthesis ,law.invention ,Magazine ,Transition metal ,High-entropy ceramics ,law ,0103 physical sciences ,Materials Chemistry ,Ceramic ,Materials ,010302 applied physics ,Materiales ,021001 nanoscience & nanotechnology ,Microstructure ,Chemical engineering ,visual_art ,Resistance to oxidation ,Ceramics and Composites ,visual_art.visual_art_medium ,0210 nano-technology - Abstract
The direct synthesis and consolidation by SPS (1950 °C, 20 min, 20 MPa) of high-entropy (Hf0.2Mo0.2Zr0.2Nb0.2Ti0.2)B2 from elemental powders resulted in a multiphase product. An increase of the heating rate determined a change of the mechanism governing the synthesis reaction from gradual solid-state diffusion to rapid combustion regime, while the final conversion degree was 67 wt.%. The sintered product displayed a non-uniform microstructure with the presence of 10–15 μm sized pores, due to volatilization phenomena occurring during the combustion synthesis reaction. In contrast, when the SPS process was preceded by powder synthesis via SHS, a homogeneous single-phase ceramic was obtained. Clear benefits are derived by the use of SHS, able to provide very shortly powders with elemental species very well intermixed, so that the obtainment of (Hf0.2Mo0.2Zr0.2Nb0.2Ti0.2)B2 during the subsequent SPS stage is strongly promoted. The resulting 92.5% dense product shows superior oxidation resistance with respect to individual borides prepared with the same method., ARCHIMEDES project sponsored by Regione Autonoma della Sardegna (Italy) - Fondo di Sviluppo e Coesione (FSC) 2014-2020 (Cod. RAS: RASSR88309, Cod. CUP: F76C18000980002). One of the authors (G.T.) performed her activity in the framework of the International PhD in Innovation Sciences and Technologies at the University of Cagliari, Italy. One of us (G.C.) acknowledges the results obtained in this manuscript as quite important for the “Ithermal” and “Generazione E” projects, sponsored by Sardegna Ricerche, Italy (Cod. CUP: F21I18000130006) and by the Italian Ministry of Education, University and Research, Italy (Cod. CUP: B96G18000560005), respectively
- Published
- 2020
36. Integrating sol-gel and carbon dots chemistry for the fabrication of fluorescent hybrid organic-inorganic films
- Author
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Róbert Ludmerczki, Pier Carlo Ricci, Maria Francesca Casula, Carlo Maria Carbonaro, Sebastiano Garroni, Plinio Innocenzi, Luigi Stagi, Luca Malfatti, and Stefania Mura
- Subjects
Nanoparticle ,chemistry.chemical_element ,lcsh:Medicine ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,chemistry.chemical_compound ,Organic-inorganic nanostructures ,lcsh:Science ,Sol-gel ,Multidisciplinary ,Quenching (fluorescence) ,Aqueous solution ,Chemistry ,lcsh:R ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Optical properties and devices ,Chemical engineering ,Triethoxysilane ,Surface modification ,lcsh:Q ,0210 nano-technology ,Luminescence ,Carbon - Abstract
Highly fluorescent blue and green-emitting carbon dots have been designed to be integrated into sol-gel processing of hybrid organic-inorganic materials through surface modification with an organosilane, 3-(aminopropyl)triethoxysilane (APTES). The carbon dots have been synthesised using citric acid and urea as precursors; the intense fluorescence exhibited by the nanoparticles, among the highest reported in the scientific literature, has been stabilised against quenching by APTES. When the modification is carried out in an aqueous solution, it leads to the formation of silica around the C-dots and an increase of luminescence, but also to the formation of large clusters which do not allow the deposition of optically transparent films. On the contrary, when the C-dots are modified in ethanol, the APTES improves the stability in the precursor sol even if any passivating thin silica shell does not form. Hybrid films containing APTES-functionalized C-dots are transparent with no traces of C-dots aggregation and show an intense luminescence in the blue and green range.
- Published
- 2020
37. In situ synchrotron radiation investigation of V2O5–Nb2O5 metastable compounds: transformational kinetics at high temperatures with a new structural solution for the orthorhombic V4Nb20O60 phase
- Author
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Nina Senes, Laura Caggiu, Gabriele Mulas, Hujun Cao, Stefano Enzo, Antonio Iacomini, Sebastiano Garroni, Elisabetta Gavini, Claudio Pistidda, and Valeria Farina
- Subjects
Inorganic Chemistry ,Pearson symbol ,Tetragonal crystal system ,Materials science ,chemistry ,Analytical chemistry ,Vanadium ,chemistry.chemical_element ,Orthorhombic crystal system ,Powder diffraction ,Amorphous solid ,Diffractometer ,Solid solution - Abstract
Due to the considerable interest in vanadium niobium oxides as a lithium storage material, the kinetics and transformation processes of the V2O5–5Nb2O5 system have been investigated by in situ synchrotron powder X-ray diffraction. The diffraction data after the thermal treatments selected with a view on the most significant features were supplemented with specific ex situ experiments conducted using a laboratory rotating anode X-ray diffractometer. The morphological changes of the mixed powders assuming an amorphous and nanocrystalline solid solution structure as a function of the temperature were inspected by scanning electron microscopy observations. The structural solution of the powder diffraction pattern of the phase recorded in situ at a temperature of about 700 °C was compatible with an orthorhombic crystal structure with the space group Amm2. The obtained lattice parameters for this structure were a = 3.965 A; b = 17.395 A, c = 17.742 A, and the cell composition was V4Nb20O60, Pearson symbol oA84, and density = 4.10 g cm−3. In this structure, while the niobium atoms may be four-, five-, and six-fold coordinated by oxygen atoms, the vanadium atoms were six-fold or seven-fold coordinated. At the temperature of 800 °C and just above, the selected 1 : 2 and 1 : 3 V2O5–Nb2O5 compositions, respectively, returned mostly a tetragonal VNb9O25 phase, in line with earlier observations conducted for determination of the stability phase diagram of such quasi-binary systems.
- Published
- 2020
38. Unveiling redox mechanism at the iron centers in the mechanochemically activated conversion of CO
- Author
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Valeria, Farina, Maria Domenica, Simula, Alessandro, Taras, Luca, Cappai, Moulay Tahar, Sougrati, Gabriele, Mulas, Sebastiano, Garroni, Stefano, Enzo, and Lorenzo, Stievano
- Abstract
The transformation of olivine during the conversion of COThe online version contains supplementary material available at 10.1007/s10853-022-06962-x.
- Published
- 2021
39. Processing, microstructure, electrical properties and cytotoxic behaviour of lead-free 0.99K0.5Na0.5NbO3-0.01BiFeO3 piezoceramics prepared using Spark Plasma Sintering (SPS)
- Author
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Antonio Iacomini, Sebastiano Garroni, Marzia Mureddu, Luca Malfatti, Swapneel Thakkar, Roberto Orrù, Simone Barbarossa, Ekaterina Pakhomova, Giacomo Cao, Juan Antonio Tamayo-Ramos, Sandra de la Parra, Carlos Rumbo, Álvaro Garcìa, José F. Bartolomé, and Lorena Pardo
- Subjects
Inorganic Chemistry ,Materials Chemistry ,Ceramics and Composites ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
40. Variation of Used Vegetable Oils’ Composition upon Treatment with Algerian Clays
- Author
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Sabrine Kawther Abdoun, Nina Senes, Safia Taleb, Alberto Mannu, Sara Brini, Abdelhak Serouri, Sebastiano Garroni, and Zoubida Taleb
- Subjects
bentonite ,Context (language use) ,Management, Monitoring, Policy and Law ,vegetable oils recycling ,Pulp and paper industry ,Environmental sciences ,FT-IR ,Vegetable oil ,waste vegetable oils ,Bentonite ,Edible oil ,Environmental science ,General Materials Science ,Composition (visual arts) ,GE1-350 ,Treatment time ,Multivariate statistical ,Waste Management and Disposal ,Chemical composition - Abstract
The treatment of used vegetable oils (UVOs) with clays represents a pivotal step in their industrial recycling process as well as one of the most challenging topics for researchers. In particular, cheap, effective, and sustainable powders need to be explored in order to develop new processes which produce beneficial results in relation to economic and environmental aspects. In this context, five samples within commercial and waste vegetable oils were treated with two sodium- and calcium-based bentonites employing a low oil/bentonite ratio (0.15 wt%). The outcomes of the processes were monitored by FT-IR spectroscopy and compared with the data relative to the parent commercial edible oil. In particular, treatment of FT-IR data by multivariate statistical analysis allowed us to determine a chemical fingerprint characteristic of each sample. Important relationships between the overall chemical composition and the specific clay employed and the treatment time (2 or 4 h) were highlighted. Finally, N2 physisorption, TEM microscopy, and FT-IR analyses of the more efficient Na bentonite allowed us to characterize the material and thus to furnish all the information needed to set-up a general protocol for the partial regeneration of waste vegetable oil destined for further processing.
- Published
- 2021
- Full Text
- View/download PDF
41. Processing Optimization and Toxicological Evaluation of 'Lead-Free' Piezoceramics: A KNN-Based Case Study
- Author
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Gabriele Mulas, Stefano Enzo, Marzia Mureddu, Carlos Rumbo, Irem Urgen, Juan Antonio Tamayo-Ramos, Antonio Iacomini, and Sebastiano Garroni
- Subjects
Technology ,Potassium niobate ,Materials science ,Pellets ,Sintering ,02 engineering and technology ,01 natural sciences ,Article ,sodium potassium niobate ,chemistry.chemical_compound ,Mechanochemistry ,0103 physical sciences ,Phenomenological model ,General Materials Science ,010302 applied physics ,Microscopy ,QC120-168.85 ,QH201-278.5 ,021001 nanoscience & nanotechnology ,Microstructure ,Engineering (General). Civil engineering (General) ,Piezoelectricity ,X-ray diffraction ,TK1-9971 ,lead-free piezoceramics ,Chemical engineering ,chemistry ,Descriptive and experimental mechanics ,processing ,Crystallite ,Electrical engineering. Electronics. Nuclear engineering ,mechanochemistry ,TA1-2040 ,0210 nano-technology ,toxicity assays - Abstract
Due to the ever-increasing limitations of the use of lead-based materials, the manufacturing of lead-free piezoceramics with competitive piezoelectric properties and established nontoxicity is considered a priority for the scientific and industrial community. In this work, a lead-free system based on sodium potassium niobate (KNN), opportunely modified with MgNb2O6 (MN), was prepared through a combination of a mechanochemical activation method and air sintering, and its toxicity was evaluated. The effect of the mechanical processing on the microstructure refinement of the processed powders was established by X-ray diffraction and the average crystallite size content of the Nb2O5 species was evaluated. The experimental evidence was rationalized using a phenomenological model which permitted us to obtain the amount of powder processed at each collision and to optimize the activation step of the pre-calcined reagents. This influenced the final density and piezoresponse of the as-sintered pellets, which showed optimal properties compared with other KNN systems. Their toxicological potential was evaluated through exposure experiments to the pulverized KNN-based pellets, employing two widely used human and environmental cellular models. The in vitro assays proved, under the selected conditions, the absence of cytotoxicity of KNN-bases systems here studied.
- Published
- 2021
42. Carbon Dots from Citric Acid and its Intermediates Formed by Thermal Decomposition
- Author
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Stefania Mura, Sebastiano Garroni, Sergio Marras, István M. Mándity, Luca Malfatti, Carlo Maria Carbonaro, Laura Calvillo, Plinio Innocenzi, Róbert Ludmerczki, Massimo Carraro, Nina Senes, and Gaetano Granozzi
- Subjects
optical properties ,Quenching (fluorescence) ,010405 organic chemistry ,Organic Chemistry ,Thermal decomposition ,chemistry.chemical_element ,General Chemistry ,Reaction intermediate ,citric acid ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Fluorescence ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,X-ray photoelectron spectroscopy ,decomposition pathways ,carbon dots ,fluorescence ,Absorption (chemistry) ,Citric acid ,Carbon - Abstract
Thermal decomposition of citric acid is one of the most common synthesis methods for fluorescent carbon dots; the reaction pathway is, however, quite complex and the details are still far from being understood. For instance, several intermediates form during the process and they also give rise to fluorescent species. In the present work, the formation of fluorescent C-dots from citric acid has been studied as a function of reaction time by coupling infrared analysis, X-ray photoelectron spectroscopy, liquid chromatography/mass spectroscopy (LC/MS) with the change of the optical properties, absorption and emission. The reaction intermediates, which have been identified at different stages, produce two main emissive species, in the green and blue, as also indicated by the decay time analysis. C-dots formed from the intermediates have also been synthesised by thermal decomposition, which gave an emission maximum around 450 nm. The citric acid C-dots in water show short temporal stability, but their functionalisation with 3-aminopropyltriethoxysilane reduces the quenching. The understanding of the citric acid thermal decomposition reaction is expected to improve the control and reproducibility of C-dots synthesis.
- Published
- 2019
43. Spark plasma sintered CaO-rich bioglass-derived glass-ceramics with different crystallinity ratios: A detailed investigation of their behaviour during biological tests in SBF
- Author
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Romano V. A. Orru, Selena Montinaro, Marina Luginina, Giacomo Cao, Valeria Cannillo, Devis Bellucci, Sebastiano Garroni, and Francesco Delogu
- Subjects
Materials Chemistry2506 Metals and Alloys ,Materials science ,Bioactive glasses ,Rietveld refinement ,Simulated body fluid ,Spark plasma sintering ,Crystallization ,In-vitro test ,Rietveld analysis ,Ceramics and Composites ,Plasma ,equipment and supplies ,law.invention ,Amorphous solid ,Crystallinity ,Chemical engineering ,law ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Ceramic - Abstract
The in-vitro behaviour of three series of dense materials with different crystallization degree and phases produced by Spark Plasma Sintering (SPS) from CaO-rich bioglass powders is investigated by soaking them up to 14 days in Simulated Body Fluid (SBF). The completely amorphous materials produced after 2 min at 730 °C display the more pronounced substrate-solution interaction. This is highly beneficial for the rapid generation (
- Published
- 2019
44. A mechanochemical route for the synthesis of VNbO5 and its structural re-investigation using structure solution from powder diffraction data
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Gabriele Mulas, Paolo Barra, Jozef Bednarcik, Claudio Pistidda, Sebastiano Garroni, Stefano Enzo, Francesco Torre, Nina Senes, and Antonio Valentoni
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Materials science ,Dopant ,Hydrogen ,010405 organic chemistry ,Rietveld refinement ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,law.invention ,Amorphous solid ,Inorganic Chemistry ,Hydrogen storage ,chemistry ,law ,ddc:540 ,Physical chemistry ,Pentoxide ,Calcination ,Powder diffraction - Abstract
Dalton transactions 48(29), 10986 - 10995 (2019). doi:10.1039/C9DT01236B, A new and solvent-free synthesis route has been adopted and optimized to prepare crystalline VNbO5 from the mechanochemical reaction between Nb2O5 and V2O5 as starting reagents. The substantially amorphous mixture of equimolar pentoxide V and Nb metals observed after extended mechanical treatment transforms into a crystalline powder following calcination under mild conditions at 710 K. The structure solution of the X-ray diffraction pattern using a global optimization approach, combined with Rietveld refinement, points to a space group P212121 (no. 19) different from Pnma (no. 62) previously proposed in the literature assuming it to be isostructural to VTaO5. The new space group helps to describe weak peaks that remained previously unaccounted for and allows more reliable determination of atomic fractional coordinates and interatomic distance distribution. The as-prepared VNbO5 has been tested as a dopant (5 wt%) for the purpose of solid state hydrogen storage, decreasing significantly the release of hydrogen of MgH2/Mg (620 K) and further enhancing the hydrogen sorption kinetic properties., Published by Soc., London
- Published
- 2019
45. Engineering UV-emitting defects in h-BN nanodots by a top-down route
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Luigi Stagi, Luca Malfatti, Carlo Maria Carbonaro, Laura Calvillo, Stefano Enzo, Junkai Ren, Gaetano Granozzi, Plinio Innocenzi, and Sebastiano Garroni
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Materials science ,business.industry ,General Physics and Astronomy ,Boron Nitride ,Nanodots ,Photoluminescence ,Surfaces and Interfaces ,General Chemistry ,Thermal treatment ,Condensed Matter Physics ,medicine.disease_cause ,Quantum chemistry ,Fluorescence ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Etching (microfabrication) ,medicine ,Optoelectronics ,Nanodot ,business ,Phosphoric acid ,Nanoscopic scale ,Ultraviolet - Abstract
Hexagonal boron nitride (h-BN) nanodots of 10 nm have been synthesized via top-down route from bulk powders. A combination of ultrasonic and thermal treatments in phosphoric acid has been used to achieve edge etching and size reduction to the nanoscale. A new emission in the ultraviolet region, correlated to a characteristic infrared-active vibration, has been detected in the BN dots. The UV emission is stable in as-prepared samples but quenches after thermal treatments higher than 100 °C. Besides the UV band, the fluorescent emission of h-BN shows a broad band in the visible region, whose intensity reaches a maximum after thermal treatment at 200 °C. Structural and optical characterization techniques have been used to investigate the synthesis-properties relationship in h-BN and the hydroxyl covalent functionalization of the surfaces. The experiments show that the particular combination of ultrasonic treatment and etching in temperature is essential to achieve the UV fluorescent emission. Quantum chemistry calculations have been used to evaluate Stones-Wales defects as possible causes of the optical and vibrational properties.
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- 2021
46. Ce Doping Boosts the Thermo- and Photocatalytic Oxidation of CO at Low Temperature in TiZrO4 Solid Solutions
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Stefano Agnoli, Panjuan Tang, Sebastiano Garroni, Elio Giamello, Stefano Livraghi, and Luca Malfatti
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Materials science ,Mechanical Engineering ,Doping ,CO oxidation ,law.invention ,electron paramagnetic resonance ,Chemical engineering ,Mechanics of Materials ,law ,Photocatalysis ,Electron paramagnetic resonance ,ternary oxides ,photocatalysis ,Solid solution - Published
- 2021
47. Size Selectivity in the Hydroxylation of Esters of Unsaturated Fatty Acids
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Ugo Azzena, Massimo Carraro, Luisa Pisano, Elisa Pintus, Salvatore Pintus, Riccardo Polese, Pierpaolo Satta, Silvia Gaspa, Lidia De Luca, Alessandro Taras, and Sebastiano Garroni
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General Chemistry ,Industrial and Manufacturing Engineering ,Food Science ,Biotechnology - Published
- 2022
48. Application of IR and UV–VIS spectroscopies and multivariate analysis for the classification of waste vegetable oils
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Luca Malfatti, Alberto Mannu, Sebastiano Garroni, and Matteo Poddighe
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Economics and Econometrics ,Qualitative analysis ,Multivariate analysis ,Vegetable oil ,Principal component analysis ,Environmental science ,Waste oil ,Linear discriminant analysis ,Spectral data ,Pulp and paper industry ,Waste Management and Disposal - Abstract
Due to the ever-increasing worldwide interest in the exploitation of waste vegetable oils, the development of analytical tools able to detect their adulteration with edible oils, is considered a priority for the scientific and industrial community. In this work, edible and waste vegetable oils have been analysed by Fourier Transform-InfraRed (FT-IR) and Ultraviolet-Visible (UV–VIS) spectroscopies and the corresponding spectral data subjected to statistical multivariate analysis for classification purposes. In particular, Principal Component Analysis (PCA) and Partial Least Square Discriminant Analysis (PLS-DA) were performed in order to develop an analytical tool which is able to distinguish between edible and waste vegetable oil. Qualitative analysis of the spectra suggested FT-IR and UV–VIS as the more suitable techniques to distinguish between wastes and edible samples. Also, statistical multivariate analysis revealed that FT-IR-based methodology is more adequate for the target, even if the elevated sensibility of the method produces an undesired distinction between edible oils of the same type. Finally, further attempts on UV–VIS data obtained in reflection mode allowed to produce a good dataset which after statistical treatment gave a clear differentiation between edible and waste oil samples.
- Published
- 2022
49. Ammonium Salts Catalyzed Acetalization Reactions in Green Ethereal Solvents
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Sebastiano Garroni, Martina Corrias, Lidia De Luca, Silvia Gaspa, Riccardo Polese, G. Satta, Rosella Crisafulli, Ugo Azzena, Luigi Urtis, Salvatore Pintus, Massimo Carraro, Luisa Pisano, Luca Nuvoli, Michela Sanna, and Nina Senes
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chemistry.chemical_classification ,ammonium salts ,Cyclopentyl methyl ether ,characterization of heterogeneous catalysts ,lcsh:Chemical technology ,Heterogeneous catalysis ,Toluene ,acetals ,Catalysis ,lcsh:Chemistry ,chemistry.chemical_compound ,heterogeneous catalysis ,lcsh:QD1-999 ,chemistry ,Azeotrope ,Organic chemistry ,lcsh:TP1-1185 ,Ammonium ,Physical and Theoretical Chemistry ,Chemoselectivity ,Counterion ,green solvents - Abstract
Cyclopentyl methyl ether and 2-methyltetrahydrofuran, low impact ethereal solvents forming a positive azeotrope with water, were successfully employed as solvents in the synthesis of a variety of acetals carried out under Dean&ndash, Stark conditions in the presence of heterogeneous acidic catalysts. Under these conditions, ammonium salts, either as such or supported on SiO2, performed better or equally well than widely employed homogeneous and heterogeneous acidic catalysts such as p-toluenesulfonic acid, Amberlyst 15®, or Montmorillonite K10. Several examples highlight the advantage of tuning the relative acidities of ammonium salts by appropriately selecting the counterion. Within one of these examples, our protocol clearly outweighs the classic p-toluenesulfonic acid/toluene protocol in terms of chemoselectivity. Silica-supported catalysts were characterized by SEM, TEM, and FTIR spectroscopies, as well as by N2 physisorption. Such a characterization reveals an even distribution of ammonium salts on silica, thus confirming the formation of expected catalytic supports.
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- 2020
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50. Enhanced Stability of Li-RHC Embedded in an Adaptive TPX Polymer Scaffold
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Prokopios Georgopanos, Chiara Milanese, Volker Abetz, Julián Puszkiel, Clarissa Abetz, Martin Dornheim, Thi Thu Le, Sebastiano Garroni, Giovanni Capurso, Claudio Pistidda, and Thomas Klassen
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Work (thermodynamics) ,Scaffold ,Materials science ,Cyclohexane ,Composite number ,02 engineering and technology ,Confinement ,Confined complex hydrides ,Carbon-based polymer ,Hydrogen storage ,010402 general chemistry ,lcsh:Technology ,01 natural sciences ,Article ,hydrogen storage ,chemistry.chemical_compound ,carbon-based polymer ,General Materials Science ,lcsh:Microscopy ,Ball mill ,ddc:620.11 ,lcsh:QC120-168.85 ,chemistry.chemical_classification ,lcsh:QH201-278.5 ,lcsh:T ,Polymer ,021001 nanoscience & nanotechnology ,confined complex hydrides ,0104 chemical sciences ,chemistry ,Chemical engineering ,lcsh:TA1-2040 ,confinement ,lcsh:Descriptive and experimental mechanics ,Chemical stability ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,lcsh:TK1-9971 - Abstract
In this work, the possibility of creating a polymer-based adaptive scaffold for improving the hydrogen storage properties of the system 2LiH+MgB2+7.5(3TiCl3·, AlCl3) was studied. Because of its chemical stability toward the hydrogen storage material, poly(4-methyl-1-pentene) or in-short TPXTM was chosen as the candidate for the scaffolding structure. The composite system was obtained after ball milling of 2LiH+MgB2+7.5(3TiCl3·, AlCl3) and a solution of TPXTM in cyclohexane. The investigations carried out over the span of ten hydrogenation/de-hydrogenation cycles indicate that the material containing TPXTM possesses a higher degree of hydrogen storage stability.
- Published
- 2020
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