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General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Electrochimie, Electrochemistry, Cinétique et mécanisme des réactions, Kinetics and mechanism of reactions, Carbone, Carbon, Carbono, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Durabilité, Durability, Durabilidad, Dynamique, Dynamics, Dinámica, Electrocatalyse, Electrocatalysis, Electrocatálisis, Nanofil, Nanowires, Protection environnement, Environmental protection, Protección medio ambiente, Support, Soporte, Dynamic drive cycle testing, PEMFCs, PtNW/C electrocatalyst, and Stack

Carbon supported platinum nanowires (PtNW/C) synthesized by a simple and inexpensive template-free methodology has been used for the first time as a cathode catalyst in a 15 cell with an active area of 250 cm2, 1.5 kW proton exchange membrane fuel cell (PEMFC) stack. Drive cycle testing along with in-situ and ex-situ accelerated degradation testing (ADT) showed that the PtNW/C catalyst exhibited better durability than commercial Pt/C. After a 420 h dynamic drive cycle durability testing, the PEMFC stacks exhibited a performance degradation rate of 14.4% and 17.9% for PtNW/C and commercial Pt/C based cathodes, respectively. It was found that the majority of performance loss was due to degradation of the commercial Pt/C anode materials, resulting from the rapidly changing load frequencies used in the testing protocol, ultimately leading to harsh fuel/air starvation conditions and subsequent Pt nanoparticle growth and agglomeration. Notably, based on post-testing characterization, the structure, electrochemically active surface area (ECSA) and oxygen reduction activity of the PtNW/C cathode catalyst remained unchanged during the drive cycling, indicating its excellent stability under these practical conditions. Conversely, when using commercial Pt/C as a cathode catalyst, significant Pt nanoparticle growth and agglomeration were observed, resulting in the reduced PEMFC stack durability. Therefore, PtNW/C materials are presented as promising replacements to conventional Pt/C as cathode electrocatalysts for PEMFCs, and particularly demonstrate improved stability under the practical conditions encountered for automotive applications.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Enzyme immobilisée, Immobilized enzyme, Enzima inmovilizada, Estérification, Esterification, Esterificación, Réaction catalytique, Catalytic reaction, Reacción catalítica, Sonochimie, Sonochemistry, Sonoquímica, Stabilité, Stability, Estabilidad, Synthèse, Synthesis, Síntesis, Tamis moléculaire, Molecular sieve, Tamiz molecular, Ultrason, Ultrasound, Ultrasonido, Butyrique acide ester éthyle, Esterification reactions, Lipases, Lipozyme TL-IM, Molecular sieves, and Operational stability

In this work, the combined use of ultrasound energy and molecular sieves was investigated for the synthesis of ethyl butyrate, ester with mango and banana notes, catalyzed by the immobilized lipase from Thermomyces lanuginosus (Lipozyme TL-IM). Initially, the best concentrations of biocatalysts (35%) and butyric acid (0.7 M) were tested using ultrasound as an alternative to mechanical agitation. The amount of acid in the reaction could be increased by 2-fold when compared to previous works where mechanical agitation was used. In the next step, substrate molar ratio and reaction temperature were optimized and the best conditions were at their lowest levels: 1:1 (acid:alcohol), and 30 °C, reaching 61% of conversion in 6 h. Molecular sieves (3 A) were added to optimized reaction medium in order to remove the formed water and improve the maximum yield. The reaction yield increased 1.5 times, reaching 90% of conversion in 6 h, when 60 mg of molecular sieves per mmol of butyric acid was used. Finally, the reuse of Lipozyme TL-IM for the ultrasound-assisted synthesis of ethyl butyrate was verified for 10 batches, without any appreciable loss of activity, whereas in systems using mechanical agitation, the biocatalyst was completely inactivated after 5 batches. These results suggest that the combined use of ultrasound and molecular sieves greatly improve esterification reactions by stabilizing the enzyme and increasing yields.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Matériaux poreux, Porous materials, Composé binaire, Binary compound, Compuesto binario, Composé de métal de transition, Transition element compounds, Matériau poreux, Porous material, Material poroso, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Mésoporosité, Mesoporosity, Mesoporosidad, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Silice, Silica, Sílice, Synthèse, Synthesis, Síntesis, Photocatalyseur, Photocatalyst, SiO2, Hierarchical macro-mesoporous silica, Si-Cr-Ti, and Visible-light driven photocatalysis

Hierarchical macro-mesoporous silica materials co-incorporated with Crand Ti were directly synthesized by adopting close-packed array of polystyrene microsphere as hard template for macropore through a simple soaking-calcination way, where Si/Ti ratio was fixed at 200 and Si/Cr ratio was set between 200 and 10. Ti specie is highly dispersed in porous matrix and Cr specie mainly exists as tetra-coordinated CrO3 at higher Si/Cr ratio (Si/Cr ≥ 50), which transforms to a mixture of CrO3 and crystallized hexa-coordinated Cr2O3when Si/Cr ratio is below 50. This highly interconnected porous material co-incorporated with Cr and Ti presents highest visible-light driven photocatalytic activity at Si/Cr = 20 toward degradation of A07. Moreover, macro-mesoporous photocatalyst presents higher activity than those of macroporous and mesoporous ones at the same Si/Cr ratio. The improved visible light driven catalytic activity is mainly attributed to effective metal to metal charge transfer from Cr(VI) to Ti(IV) benefitted from the uniform dispersion of these two species in hierarchical porous silica matrix.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Acide carboxylique, Carboxylic acid, Acido carboxílico, Composé de métal de transition, Transition element compounds, Acide formique, Formic acid, Fórmico ácido, Acide lactique, Lactic acid, Láctico ácido, Acide organique, Organic acids, Acido orgánico, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Condition hydrothermale, Hydrothermal condition, Condición hidrotermal, Magnésie, Magnesia, Oxyde de cuivre, Copper oxide, Cobre óxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Sucre, Sugar, Azúcar, Synthèse, Synthesis, Síntesis, Alkaline hydrothermal synthesis, Copper oxide catalysis, and Sugars

Design of a suitable catalyst for the conversion of inedible-biomass, a renewable resource, into high-value chemicals is an immense and important area of research in an era of energy crisis. This paper demonstrates batch conversion of sugars into lactic acid (LA) and formic acid (FA) employing a supported copper catalyst. A magnesia-supported copper catalyst was synthesized by a hydrothermal methodology using CTAB as the capping agent (denoted as CuCTAB/MgO). We found that the CuCTAB/MgO not only dramatically boosted the yields of LA and FA from sugars but also decreased the energy demand of the process by decreasing the reaction temperature from 523 K to 393 K. The high yields of LA (70%) in the presence of NaOH and of FA (65%) in the presence of H2O2 were achieved from glucose at 393 K in water using a CuCTAB/MgO catalyst, which could be recycled without any significant loss of activity. The copper catalyst was also found to exhibit excellent activity for the transformation of other sugars. The catalyst was characterized using PXRD, H2-TPR, N2 adsorption-desorption, and other analytical techniques to investigate the active Cu species and propose a plausible mechanistic pathway to LA.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dégradation photochimique, Photochemical degradation, Degradación fotoquímica, Microparticule, Microparticle, Micropartícula, Microsphère, Microsphere, Microsfera, Mécanisme, Mechanism, Mecanismo, Oxyde de bismuth, Bismuth oxide, Bismuto óxido, Particule sphérique, Spherical particle, Partícula esférica, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Précurseur, Precursor, Synthèse, Synthesis, Síntesis, Photodegradation mechanism, Visible-light photocatalysis, o-Phenylphenol, p-n junction, and β-Bi2O3/Bi2O2CO3 microspheres

Novel flower-like heterostructured β-Bi2O3/Bi2O2CO3 microspheres are synthesized by calcining a Bi2O2CO3 self-sacrifice precursor for the visible-light photocatalytic degradation of o-phenylphenol (OPP. is a widely used fungicide and preservative agent). The Bi2O2CO3 microspheres are firstly prepared under hydrothermal conditions, and then converted to Bi2O3 by thermal treatment. With increasing the calcining temperature from 250 to 500 °C, an in situ stepwise decomposition reaction take place during the course of calcination, described as: Bi2O2CO3 → β-Bi2O3/Bi2O2CO3 → β-Bi2O3 → β-Bi2O3/α-Bi2O3 → α-Bi2O3. The β-Bi2O3/Bi2O2CO3 microspheres synthesized at 300 °C exhibit excellent photocatalytic activity under visible-light irradiation, which can degrade 99.8% OPP in 45 min. And the degradation rate of the heterostructured photocatalyst is approximately 2, 2.6, 6, 13, 80, and 827 times higher than that of single P-Bi2O3, mixed β-Bi2O3 and Bi2O2CO3, commercial β-Bi2O3, α-Bi2O3, N-doped TiO2, and Bi2O2CO3, respectively. The superior photoreactivity of the β-Bi2O3/Bi2O2CO3 is attributed to the enhanced charge separation and transfer due to the formation of p-n junction with large heterojunction interface, favorable band gap energy (2.27 eV), relatively high specific surface areas (12.5 m2 g-1), and flower-like hierarchical micro/nano structures. In addition, the degradation intermediates including ethyl phenethyl ether, phenyl acetaldehyde, and phenylacetic acid are identified. And the results also reveal that the photogenerated holes and •O2- radicals are primarily reactive species in the photocatalytic system, which are the key factors responsible for the nearly complete mineralization of OPP.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie de surface, Surface physical chemistry, Echange d'ions, Ion-exchange, Zéolites: préparations et propriétés, Zeolites: preparations and properties, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Chabazite, Chabasita, Echange ion, Ion exchange, Cambio iónico, Etat solide, Solid state, Estado sólido, Moteur diesel, Diesel engine, Motor diesel, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réaction one pot, One pot reaction, Reacción one pot, Réduction chimique, Chemical reduction, Reducción química, Synthèse, Synthesis, Síntesis, Zéolite, Zeolite, Zeolita, SAPO-34, Cu/SAPO-34, Emission control, NOx, and Selective catalytic reduction

Cu/SAPO-34 catalysts are synthesized using two methods: solid-state ion exchange (SSIE) and one-pot synthesis. SSIE is conducted by calcining SAPO-34/CuO mixtures at elevated temperatures. For the one-pot synthesis method, Cu-containing chemicals (CuO and CuSO4) are added during gel preparation. A high-temperature calcination step is also needed for this latter method. Catalysts are characterized with surface area/pore volume measurements, temperature programmed reduction (TPR), electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopies, and scanning electron microscopy (SEM). Catalytic properties are examined using standard ammonia selective catalytic reduction (NH3-SCR) and ammonia oxidation reactions. For Cu/SAPO-34 samples prepared by SSIE, Cu presents both as isolated Cu2+ ions and unreacted CuO. The former are highly active and selective in NH3-SCR, while the latter catalyzes a side reaction; notably, the non-selective oxidation of NH3 above 350°C. Using the one-pot method followed by a high-temperature aging treatment, it is possible to form Cu/SAPO-34 samples with predominately isolated Cu2+ ions at low Cu loadings. However at much higher Cu loadings, isolated Cu2+ ions that bind weakly with the CHA framework and CuO clusters also form. These Cu moieties are very active in catalyzing non-selective NH3 oxidation above 350°C. At very low reaction temperature temperatures (<155°C), standard NH3-SCR over Cu/SAPO-34 catalysts appears to be kinetically limited. However at higher temperatures, multiple rate limiting factors are possible.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Alcool, Alcohol, Composé benzénique, Benzenic compound, Compuesto bencénico, Composé de métal de transition, Transition element compounds, Autoorganisation, Self organization, Autoorganización, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dégradation photochimique, Photochemical degradation, Degradación fotoquímica, Nanotube, Nanotubo, Oxyde de titane, Titanium oxide, Titanio óxido, Phénol, Phenol, Fenol, Phénols, Phenols, Fenoles, Protection environnement, Environmental protection, Protección medio ambiente, Synthèse, Synthesis, Síntesis, Titanate, Titanates, Titanato, Photocatalytic degradation of phenol, and Self organized TiO2 nanotube layers

This study proposes a direct synthetic route to single titanate sheets through the mild and versatile conditions of the chimie douce. The stages of the production include the complexation of the titanium alkoxide precursor by benzoic acid, the formation of titanium oxo-clusters and their controlled transformation into single sheet titanates during the hydrolysis stage. The resulted material appears to be an excellent precursor for self-organized TiO2 nanotubes formation which presents an excellent activity as photocatalyst in the photo-degradation of phenol.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé binaire, Binary compound, Compuesto binario, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Composé de lanthanide, Lanthanide compound, Lantánido compuesto, Cordiérite, Cordierite, Cordierita, Gaz synthèse, Synthesis gas, Gas síntesis, Méthane, Methane, Metano, Oxyde de cérium, Cerium oxide, Cerio óxido, Protection environnement, Environmental protection, Protección medio ambiente, Reformage vapeur, Steam reforming, Reformación vapor, CeO2, CH4 oxy-steam reforming, Ceria carrier, Cordierite monoliths, Rh Pt Ni catalysts, and Syngas production

The deposition of catalytic layers as Rh, Pt, Ni (noble metals load equal to 1.5 wt.%, Ni load equal to 7.5 wt.%) on CeO2, over cordierite monoliths (400 cpsi, diameter 1 cm, length 1.5 cm), prepared through a combination of the solution combustion synthesis followed by the Wet Impregnation technique, was investigated. The performances of the structured catalysts were evaluated towards the methane Oxy-Steam Reforming (OSR) reaction. The physicochemical properties of the catalysts at powder level were investigated by X-ray Diffraction, CO chemisorption and nitrogen adsorption (BET), whereas the characteristics of the structured catalysts in terms of thickness and coating integrity were investigated by Scanning Electron Microscopy (SEM), mechanical strength and pressure drop tests. Moreover, the morphology of catalytic layers was investigated by Transmission Electron Microscopy (TEM) on the powder obtained by mechanically scraping the monoliths internal walls. The prepared structured catalysts were tested and compared towards the CH4 OSR reaction varying the temperature (500-800°C), the weight space velocity (WSV = 33,000-400,000 Nml gcat-1 h-1), at fixed molecular oxygen-to-carbon (O/C = 0.55) and steam-to-carbon (S/C = 1.2) molar ratios. The catalytic monoliths presented a uniform thin coating with thickness between 20 and 25 μm, high mechanical strength and low pressure drop. Regarding the catalytic activity, at low WSV all of the structured catalysts showed similar performances. Instead, increasing the WSV, the catalytic monolith loaded with 1.5 wt.% Rh/CeO2 performed slightly better than the other samples, maintaining almost constant the methane conversion and the CO selectivity even at 400,000 Nml gcat-1 h-1.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Dioxyde de carbone, Carbon dioxide, Carbono dióxido, Etat supercritique, Supercritical state, Estado supercrítico, Extraction, Extracción, Modélisation, Modeling, Modelización, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Capsaicinoids, Mathematical modeling, Microscopy, Pepper, and Supercritical extraction

Extracts from malagueta pepper (Capsicum frutescens L.) were obtained using supercritical fluid extraction (SFE) assisted by ultrasound, with carbon dioxide as solvent at 15 MPa and 40 °C. The SFE global yield increased up to 77% when ultrasound waves were applied, and the best condition of ultrasound-assisted extraction was ultrasound power of 360 W applied during 60 min. Four capsaicinoids were identified in the extracts and quantified by high performance liquid chromatography. The use of ultrasonic waves did not influence significantly the capsaicinoid profiles and the phenolic content of the extracts. However, ultrasound has enhanced the SFE rate. A model based on the broken and intact cell concept was adequate to represent the extraction kinetics and estimate the mass transfer coefficients, which were increased with ultrasound. Images obtained by field emission scanning electron microscopy showed that the action of ultrasonic waves did not cause cracks on the cell wall surface. On the other hand. ultrasound promoted disturbances in the vegetable matrix, leading to the release of extractable material on the solid surface. The effects of ultrasound were more significant on SFE from larger solid particles.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Alcool, Alcohol, Composé benzénique, Benzenic compound, Compuesto bencénico, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Chlorophénol, Chlorophenol, Clorofenol, Composé du chlore, Chlorine compounds, Cloro compuesto, Dégradation, Degradation, Degradación, Minéralisation, Mineralization, Mineralización, Nanocomposite, Nanocompuesto, Oxyde de bismuth, Bismuth oxide, Bismuto óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Phénols, Phenols, Fenoles, Protection environnement, Environmental protection, Protección medio ambiente, Photocatalyseur, Photocatalyst, 2-Chlorophenol degradation, 2-Nitrophenol degradation, Bi2O3 based photocatalyst, and Sunlight photocatalysis

The photocatalytic mineralization of 2-chlorophenol (2-CP) and 2-nitrophenol (2-NP) was investigated using α-Bi2O3. The experiments were performed both in complete spectrum and in the visible region (420-800 nm) of the sunlight. The materials were fully characterized by means of UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM). α-Bi2O3 showed considerably higher activity for the mineralization of 2-nitrophenol and 2-chlorophenol under natural sunlight exposure, however still appreciable activity was observed in the visible region. Formation of surface nanocomposites Bi2O4-x-Bi2O3 was observed under sunlight irradiation due to the presence of UV light. The sunlight exposed Bi2O3, i.e. Bi2O4-xBi2O3 composite, showed excellent activity for the degradation and mineralization of 2-CP and 2-NP in the visible region of sunlight. A key role of both hydroxyl and superoxide anion radicals was evidenced in the degradation and mineralization processes under sunlight while only hydroxyl radicals were identified as major facilitators under visible light irradiation.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Cinétique, Kinetics, Cinética, Dégradation, Degradation, Degradación, Eau, Water, Agua, Mécanisme, Mechanism, Mecanismo, Oxydation, Oxidation, Oxidación, Ozone, Ozono, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Mechanisms, Pathways, and Sulfamethoxazole

In this research, sulfamethoxazole (SMX) degradation was investigated using ultrasound (US), ozone (O3) and ultrasound/ozone oxidation process (UOOP). It was proved that ultrasound significantly enhanced SMX ozonation by assisting ozone in producing more hydroxyl radicals in UOOP. Ultrasound also made the rate constants improve by kinetics analysis. When ultrasound was added to the ozonation process, the reaction rate increased by 6-26% under different pH conditions. Moreover, main intermediates oxidized by US, O3 and UOOP system were identified. Although the main intermediates in ozonation and UOOP were similar, the introduction of ultrasound in UOOP had well improved the cleavage of S-N bond. In this condition SMX become much easier to be attacked, which led to enhanced SMX removal rate in UOOP compared to the other two examined processes. Finally, the SMX degradation pathways were proposed.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Sciences appliquees, Applied sciences, Energie, Energy, Combustibles, Fuels, Combustibles de remplacement. Production et utilisation, Alternative fuels. Production and utilization, Hydrogène, Hydrogen, Métal transition, Transition metal, Metal transición, Platinoïde, Platinoid, Platinoide, Carbone, Carbon, Carbono, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Hydrogénation, Hydrogenation, Hidrogenación, Hydrure, Hydrides, Hidruro, Hétérocycle, Heterocyclic compound, Heterociclo, Liquide, Liquid, Líquido, Protection environnement, Environmental protection, Protección medio ambiente, Ruthénium, Ruthenium, Rutenio, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réactivité chimique, Chemical reactivity, Reactividad química, Stockage hydrogène, Hydrogen storage, Structure, Estructura, Substitution, Substitución, Heterocyclic compounds, Liquid organic hydride, and Ruthenium catalysts

The effect of the type of heteroatom in the structure on the recyclability of possible candidate compounds for application as LOC (liquid organic carriers) was studied by comparing the rate and selectivity obtained in hydrogenation of carbazole, dibenzothiophene, dibenzofuran and fluorene. The effect of a partial saturation of the compound on its hydrogenation yield and reaction pathway was also considered by studying hydrogenation of 1,2,3,4-tetrahydrocarbazole. Using Ru black catalyst, the rate of hydrogenation was found to decrease in order; dibenzofuran > 1,2,3,4-tetrahydrocarbazole > carbazole » fluorene. No reaction was observed in the hydrogenation of dibenzothiophene under the conditions studied which was attributed to the immediate poisoning of ruthenium metal by sulphur compounds. The rate of hydrogenation of fluorene was around 3 times lower as compared to carbazole and over 8 times lower as compared to that of dibenzofuran under the same reaction conditions. With the exeption of S containing dibenzothiophene, the presence of the heteroatom in the structure was found to be beneficial in terms of increasing the rate of hydrogen loading step. Additionally, a higher reaction rate was obtained in the hydrogenation of the partially saturated 1,2,3,4-tetrahydrocarbazole as compared to the substrate carbazole. The structure and stability of intermediates was found to be significantly influenced by the type and presence of a heteroatom in the structure. A stable octahydro-intermediate was observed only with N-heterocycles, whereas a stable hexahydro-intermediate was produced in the polyaromatic hydrocarbon-fluorene. Additionally, the theoretically obtained lowest total enthalpies using DFT calculations agreed well with the stable intermediates observed experimentally in the hydrogenation of fluorene. Theoretical DFT differences in enthalpies also indicated the products of hydrogenolysis of perhydro-dibenzofuran to be the most favourable products of its hydrogenation, which agreed well with the experimental observations. Overall, taking into account the recyclability of LOC, substitution of carbon with a N heteroatom was demonstrated to be one of the promising approaches to improve the kinetics of the hydrogen loading step.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Acide carboxylique, Carboxylic acid, Acido carboxílico, Composé binaire, Binary compound, Compuesto binario, Composé de lanthanide, Lanthanide compound, Lantánido compuesto, Métal transition, Transition metal, Metal transición, Acide acétique, Acetic acid, Acético ácido, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Composé de métal de transition, Transition element compounds, Gazéification, Gasification, Gasificación, Matière volatile, Volatiles, Materia volátil, Nickel, Niquel, Oxyde de cérium, Cerium oxide, Cerio óxido, Protection environnement, Environmental protection, Protección medio ambiente, Reformage vapeur, Steam reforming, Reformación vapor, Zircone, Zirconia, Zircona, CeO2, ZrO2, Ceria-zirconia, and Humin

Acetic acid and phenols are the major components of the condensable by-products in the low temperature de-volatilisation stage of humin during gasification. Catalytic steam reforming of acetic acid using supported Ni on ceria-zirconia mixed oxide prepared via the hydrothermal route is discussed. The influence of steam reforming temperatures, steam/carbon ratios were studied. The catalyst showed high activity and good stability. Furthermore, activity improvement was achieved with multiple redox cycles as relevant to recycling the catalysts. Characterisation of the fresh and used catalyst by various techniques (e.g., LEIS, Raman spectroscopy, TPO/TPR) revealed the modification of metal-oxygen bond on the support under the steam reforming conditions. It in turn improved the oxygen mobility of the catalyst.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Bulle, Bubble, Ampolla, Force, Fuerza, Instabilité, Instability, Inestabilidad, Sonochimie, Sonochemistry, Sonoquímica, Sonoluminescence, Sonoluminiscencia, Ultrason, Ultrasound, Ultrasonido, Bi-frequency driving, Bjerknes force, Bubble clusters, Multi-bubble sonoluminescence (MBSL), Positional instability, and Static pressure

In the present work, stable clusters made of multiple sonoluminescent bubbles are experimentally and theoretically studied. Argon bubbles were acoustically generated and trapped using bi-frequency driving within a cylindrical chamber filled with a sulfuric acid aqueous solution (SA85w/w). The intensity of the acoustic pressure field was strong enough to sustain, during several minutes, a large number of positionally and spatially fixed (without pseudo-orbits) sonoluminescent bubbles over an ellipsoidally-shaped tridimensional array. The dimensions of the ellipsoids were studied as a function of the amplitude of the applied low-frequency acoustic pressure (PLFAC) and the static pressure in the fluid (P0). In order to explain the size and shape of the bubble clusters, we performed a series of numerical simulations of the hydrodynamic forces acting over the bubbles. In both cases the observed experimental behavior was in excellent agreement with the numerical results. The simulations revealed that the positionally stable region, mainly determined by the null primary Bjerknes force (FBj), is defined as the outer perimeter of an axisymmetric ellipsoidal cluster centered in the acoustic field antinode. The role of the high-frequency component of the pressure field and the influence of the secondary Bjerknes force are discussed. We also investigate the effect of a change in the concentration of dissolved gas on the positional and spatial instabilities through the cluster dimensions. The experimental and numerical results presented in this paper are potentially useful for further understanding and modeling numerous current research topics regarding multi-bubble phenomena, e.g. forces acting on the bubbles in multi-frequency acoustic fields, transient acoustic cavitation, bubble interactions, structure formation processes, atomic and molecular emissions of equal bubbles and nonlinear or unsteady acoustic pressure fields in bubbly media.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Bruit, Noise, Ruido, Coefficient absorption, Absorption coefficient, Coeficiente absorción, Erosion, Erosión, In situ, Sol, Soils, Suelo, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Acoustics, Environment, Monitoring, and Pink noise

The relationship between the sound absorption coefficient and factors of the Universal Soil Loss Equation (USLE) was determined in a section of the Maringá Stream basin, Paraná State, by using erosion plots. In the field, four erosion plots were built on a reduced scale, with dimensions of 2.0 x 12.5 m. With respect to plot coverage, one was kept with bare soil and the others contained forage grass (Brachiaria), corn and wheat crops, respectively. Planting was performed without any type of conservation practice in an area with a 9% slope. A sedimentation tank was placed at the end of each plot to collect the material transported. For the acoustic system, pink noise was used in the measurement of the proposed monitoring, for collecting information on incident and reflected sound pressure levels. In general, obtained values of soil loss confirmed that 94.3% of material exported to the basin water came from the bare soil plot, 2.8% from the corn plot, 1.8% from the wheat plot, and 1.1% from the forage grass plot. With respect to the acoustic monitoring, results indicated that at 16 kHz erosion plot coverage type had a significant influence on the sound absorption coefficient. High correlation coefficients were found in estimations of the A and C factors of the USLE, confirming that the acoustic technique is feasible for the determination of soil loss directly in the field.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie de surface, Surface physical chemistry, Métal transition, Transition metal, Metal transición, Adsorption, Adsorción, Carbone, Carbon, Carbono, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur mixte, Mixed catalyst, Catalizador mixto, Gaz à l'eau, Water gas, Gas con agua, Glycérol, Glycerol, Glicerol, Hydrogène, Hydrogen, Hidrógeno, Nanotube multifeuillet, Multiwalled nanotube, Nanotubo pared múltiple, Nickel, Niquel, Palladium, Paladio, Platine, Platinum, Platino, Platinoïde, Platinoid, Platinoide, Protection environnement, Environmental protection, Protección medio ambiente, Reformage, Reforming, Reformación, Sorption, Sorción, Support, Soporte, Bimetallic catalyst, CO2 removal, Platinum-nickel, Platinum-palladium, and Water-gas shift

In this study, multi-walled carbon nanotubes supported Pt and Pt-based bimetallic catalysts were prepared and their catalytic activities were investigated to screen effective and economical catalyst for H2 production in catalytic aqueous phase reforming (CAPR) of glycerol. Nickel promoted Pt catalyst with optimized Ni:Pt molar ratio afforded highest glycerol conversion rate (81.21%) and carbon conversion to gas (15.3%) although hydrogen gasification ratio (7.2%) was poorer than that of noble metals promoted Pt-based bimetallic catalysts. Adding CaO significantly enhanced the fraction and selectivity of H2 over Pt-Ni catalyst and those of CH4 were reduced to a negligible level, which was possibly attributed to the facilitated water-gas shift reaction and inhibited methanation through in-situ CO2 sorption via carbonation. Results suggested that Pt-Ni bimetallic catalysts improved dehydrogenation-decarboxylation and dehydration-hydrogenation reactions, leading to high glycerol conversions. Introducing CaO further favored C-C bond cleavage towards high H2 yield. The catalytic performance can be completely recovered after regenerating the catalyst and adding sacrificial CaO. In terms of reduced consumption of precious metal catalyst, excellent catalyst performance and hydrothermal stability, combination of Pt-Ni bimetallic catalyst and CaO additive was identified as an effective catalytic system for H2 production in CAPR of glycerol.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Emulsions. Microémulsions. Mousses, Emulsions. Microemulsions. Foams, Graphène, Graphene, Matériau composite, Composite material, Material compuesto, Mousse (émulsion), Foam, Espuma, Nanoparticule, Nanoparticle, Nanopartícula, Sonochimie, Sonochemistry, Sonoquímica, Supercondensateur, Supercapacitor, Supercondensador, Synthèse, Synthesis, Síntesis, Ultrason, Ultrasound, Ultrasonido, 3D foam, and Composite

Graphene and its derivatives have attracted much attention in application of electrochemical devices. Construction of three-dimensional (3D) heterostructured composites is promising for establishing high-performance devices, which enables large surface area, facilitated ion and electron transport, and synergistic effects between multicomponents. Here, we report a simple and general sonochemical-assisted synthesis to prepare various 3D porous graphene/nanoparticle (i.e., Pt, Au, Pd, Ru, and MnO2) foams using colloidal template. The 3D porous network structure of composite foams significantly improves a large surface area of around 550 m2 g-1 compared to the bare graphene (215 m2 g-1). This unique structure of 3D graphene/MnO2 enables further improvement of electrochemical characteristics, compared with bare graphene/MnO2 composite, showing a high specific capacitance of 421 F g-1 at 0.1 A g-1, high rate capability (97% retention at 20 A g-1). and good cycling performance (97% retention over 1000 cycles). Moreover, electrochemical impedance analysis demonstrates that electron and ion transfer are triggered by 3D porous structure.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Acide carboxylique, Carboxylic acid, Acido carboxílico, Oxyde de plomb, Lead oxide, Plomo óxido, Photoluminescence, Fotoluminiscencia, Plomb II, Lead II, Plomo II, Précurseur, Precursor, Quinoléine, Quinoline, Quinolina, Sonochimie, Sonochemistry, Sonoquímica, Synthèse, Synthesis, Síntesis, Ultrason, Ultrasound, Ultrasonido, Lead(II) complex, PbO, and Sonoelectrochemical synthesis

A new lead complex, [Pb(Q)2] (1) (Q= quinoline-2-carboxylic acid), was prepared via conventional electrochemical method in a fast and facile process and fully characterized by 1H and 13C NMR, IR, UV spectroscopies and elemental analysis. The nano-structures of same compound were successfully prepared at 25,48 and 60 °C by a facile and environment-friendly sonoelectrochemical route. The new nano-structure particles were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analysis. Thermal stability of single-crystal and nano-size samples of the prepared compound was studied by thermogravimetric and differential thermal analysis. The effect of sonoelectrochemical temperature on particle size has been investigated, and possible explanations offered. The photoluminescence properties of the nano-structured and crystalline bulk of the prepared complex at room temperature in the solid state have been investigated in detail. The results indicate that the size of the complex particles has an important effect on the optical properties of it. The prepared complexes, as bulk and as nano-particles, were utilized as a precursor for preparation of PbO nanoparticles by direct thermal decomposition at 600 °C in air. The nano-structures of PbO were characterized by scanning electron microscopy, X-ray powder diffraction and IR spectroscopy.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Chimie verte, Green chemistry, Química verde, Iodure de cuivre, Copper iodide, Cobre ioduro, Nanoparticule, Nanoparticle, Nanopartícula, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Sonochimie, Sonochemistry, Sonoquímica, Synthèse, Synthesis, Síntesis, Ultrason, Ultrasound, Ultrasonido, Couplage de Sonogashira, Aryl ethynyl linked triarylamines, Cul nanoparticles, Sonogashira coupling, and Ultrasonic irradiation

A simple and green method was performed to the preparation of copper iodide nanoparticles by ultrasound approach. Consequently the synthesis of aryl ethynyl linked triarylamines was carried out through the Sonogashira coupling between iodo-substituted triarylamine and aryl acetylenes in the presence of CuI nanoparticles/Pd(PPh3)2Cl2 as an efficient catalytic system and triethylamine as the base under ultrasonic irradiation. Good to excellent yields of products and short reaction times are some of the important advantages of this solvent free protocol which were attained by both nano CuI and ultrasound conditions.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Composé binaire, Binary compound, Compuesto binario, Acide, Acids, Acido, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Colorant, Dyes, Colorante, Dégradation, Degradation, Degradación, Nanoparticule, Nanoparticle, Nanopartícula, Sonochimie, Sonochemistry, Sonoquímica, Sonolyse, Sonolysis, Sonólisis, Synthèse, Synthesis, Síntesis, Textile, Textil, Ultrason, Ultrasound, Ultrasonido, Nanocatalyseur, Nanocatalyst, O Zn, Sonocatalyse, Sonocatalysis, ZnO, Sonochemical synthesis, Textile dye, Ultrasonic degradation, and ZnO nanocatalyst

Undoped and Pr-doped ZnO nanoparticles were prepared using a simple sonochemical method, and their sonocatalytic activity was investigated toward degradation of Acid Red 17 (AR17) under ultrasonic (US) irradiation. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques. The extent of sonocatalytic degradation was higher compared with sonolysis alone. The decolorization efficiency of sonolysis alone, sonocatalysis with undoped ZnO and 5% Pr-doped ZnO was 24%, 46% and 100% within reaction time of 70 min, respectively. Sonocatalytic degradation of AR17 increased with increasing the amount of dopant and catalyst dosage and decreasing initial dye concentration. Natural pH was favored the sonocatalytic degradation of AR17. With the addition of chloride, carbonate and sulfate as radical scavengers, the decolorization efficiency was decreased from 100% to 65%, 71% and 89% at the reaction time of 70 min, respectively, indicating that the controlling mechanism of sonochemical degradation of AR17 is the free radicals (not pyrolysis). The addition of peroxydisulfate and hydrogen peroxide as enhancer improved the degradation efficiency from 79% to 85% and 93% at the reaction time of 50 min, respectively. The result showed good reusability of the synthesized sonocatalyst.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Argile, Clay, Arcilla, Composé de métal de transition, Transition element compounds, Colorant organique, Organic dye, Colorante orgánico, Dégradation, Degradation, Degradación, Epuration eau usée, Waste water purification, Depuración aguas servidas, Montmorillonite, Montmorilonita, Nanocomposite, Nanocompuesto, Oxyde de titane, Titanium oxide, Titanio óxido, Sonochimie, Sonochemistry, Sonoquímica, Sonolyse, Sonolysis, Sonólisis, Ultrason, Ultrasound, Ultrasonido, Sonocatalyse, Sonocatalysis, Cationic dyes, Modified nanoclay, Sonocatalytic degradation, and Wastewater treatment

The sonocatalytic performance of the synthesized TiO2/Montmorillonite K10 (TiO2/MMT) nanocomposite was studied in removal of Basic Blue 3 (BB3) from water. The TiO2/MMT nanocomposite was prepared by hydrothermal method. Scanning electron microscope, X-ray diffraction and Fourier transform infrared were used to characterize the synthesized nanocomposite. The average size of TiO2 nanoparticles decreased from 60-80 nm to 40-60 nm through the immobilization of this semiconductor on the surface of MMT. The obtained results indicated that the sonocatalytic activity of TiO2/MMT nanocomposite was higher than that of pure TiO2 nanoparticles and MMT particles. Furthermore, the main influence factors on the sonocatalytic activity such as the BB3 concentration, pH of solution, TiO2/MMT dose, power of ultrasonic generator, and inorganic salts were studied. The intermediates of BB3 degradation during the sonocatalytic process in the presence of the TiO2/MMT nanocomposite have been monitored by gas chromatography-mass spectrometry.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Aldéhyde, Aldehyde, Aldehído, Composé de métal de transition, Transition element compounds, Acétaldéhyde, Acetaldehyde, Acetaldehído, Anatase, Anatasa, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Décomposition, Decomposition, Descomposición, Nanoplaque, Nanoplate, Nanoplaca, Oxydation, Oxidation, Oxidación, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Synthèse solvothermale, Solvothermal synthesis, Síntesis solvotermal, Acetaldehyde decomposition, Anatase nanoplates, Mn4+/TiO2, NO oxidation, and {0 0 1} facets

The photocatalytic activity of TiO2 and manganese doped TiO2 nanoplates with various manganese atomic percentages, in the range of 2-7%, was studied. The undoped and doped nanoplates with exposed {0 0 1} facets were produced by a solvothermal method. The crystal structure as well as the shape of the TiO2 and Mn4+/TiO2 anatase nanoparticles was determined with X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). Both techniques revealed that the nanocrystals are in the form of plates. Moreover, the anisotropic peak broadening of the X-ray diffraction patterns was studied using the Rietveld refining method. Chemical analysis of the photocatalyst that was carried out with X-ray photoelectron spectroscopy (XPS) showed the presence of manganese ions in the TiO2 anatase matrix. The Density Functional Theory (DFT) calculations exhibited a decrease in the energy gap and an increase in the density of the electronic stated inside the gap for the doped TiO2. These observations were in agreement with the results of the UV-visible diffuse reflectance spectroscopy (DRS) that demonstrated an adsorption shift towards the visible region for the same samples. The photocatalytic activity of the synthesized catalysts was investigated by the photocatalytic oxidation of the gaseous nitric oxide (NO) and decomposition of the gaseous acetaldehyde (CH3CHO) under visible light irradiation. The optimal concentration of dopant that improves the photocatalytic activity of the nanoplates was determined.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Composé de métal de transition, Transition element compounds, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Conversion, Conversión, Déchet, Wastes, Desperdicio, Eau mer, Seawater, Agua mar, Electrode, Electrodes, Electrodo, Energie solaire, Solar energy, Energía solar, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Rayonnement solaire, Solar radiation, Radiación solar, Réduction chimique, Chemical reduction, Reducción química, Uranium, Uranio, Metal reduction, Nuclear wastes, Photocatalytic, and Superoxide

Uranium(VI) spiked in natural seawater was photoelectrochemically reduced using porous TiO2 film electrodes at varying potential biases (EbiasS) and pH values. Linear sweep voltammograms of TiO2 electrodes in seawater with U(VI) at pH 8.2 exhibited the characteristic reduction peaks at -0.95 VSCE and anodic peaks at -0.75 VSCE. These peaks shifted anodically and became less pronounced with decreasing pH values from 8.2 to 3. At the natural seawater pH of 8.2, photoelectrochemical (PEC) treatment (Ebias = -1.0VSCE; AM 1.5 G) was found to be considerably more effective in reducing U(VI) than photocatalytic (PC) treatment (without Ebias) and electrochemical (EC) treatment (without irradiation), and even the combination of the two treatment processes. The synergistic effect of the PEC U(VI) reduction varied depending on the EbiasS and pH values, and was further confirmed by the Faradaic efficiency (e), which was close to 100%. Inductively coupled plasma spectroscopy (ICP) and detailed surface analyses of the TiO2 using various techniques (TEM/EDX, SEM/EDX, and XPS) indicated that ∼95% of uranium in the PEC-treated experiment was adsorbed on TiO2 with 57% as U4.6+ and 14% as U4+, whereas ∼98% of uranium in the EC-treated experiment remained in solution, containing 62% as U4.6+ and 12% as U4+. Under certain conditions (e.g., at a pH of 3.0 and/or with N2-purging), no reduction of U(VI) was observed irrespective of the Ebias and irradiation. To further investigate the observed lack of U(VI) reduction, surface chemistry and energetics between TiO2 and U(VI) were studied as a function of pH. Finally, a role of superoxide radicals as an electron shuttle between TiO2 and U(VI) was established as a primary U(VI) reduction mechanism.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Composé binaire, Binary compound, Compuesto binario, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Composé de lanthanide, Lanthanide compound, Lantánido compuesto, Composé de métal de transition, Transition element compounds, Décomposition, Decomposition, Descomposición, Nanoparticule, Nanoparticle, Nanopartícula, Nanosphère, Nanosphere, Nanosfera, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Oxyde de cérium, Cerium oxide, Cerio óxido, Particule sphérique, Spherical particle, Partícula esférica, Protection environnement, Environmental protection, Protección medio ambiente, Protoxyde d'azote, Nitrogen protoxide, Nitrógeno protóxido, Réaction catalytique, Catalytic reaction, Reacción catalítica, CeO2, CuO, CeO2 nanospheres, CuO-CeO2 catalysts, N2O decomposition, Small CuO clusters, and Synergetic effect

High surface area CeO2 nanospheres as an active catalyst support were synthesized using glycothermal approach. Different loadings of copper (4, 6, 10 and 15 wt.%) were supported by wet impregnation method. Prepared materials were characterized by means of TEM, SEM-EDX, XRD, UV-Vis diffuse reflectance, N2 adsorption/desorption, DRIFT and H2-TPR techniques, and tested for the catalytic reaction of nitrous oxide decomposition. The best activity in the N2O degradation was found for the sample containing 10 wt.% of Cu that can be attributed to the highest number of small CuO clusters on the catalyst surface. Further increase of copper content strongly affects the dispersion and leads to the formation of less active segregated CuO phase, which was confirmed by XRD, UV-Vis and H2-TPR results. Accordingly to UV-Vis examination and DRIFT analysis using CO as a probe molecule, all solids contain Cu+1 ions which play a crucial role in the N2O decomposition mechanism. The synthesized catalysts were also tested in wet or NO containing atmospheres, where an inhibiting effect takes place and leads to shifting of conversion profiles to higher temperature by 65 and 10 °C, correspondingly. It was found out that the formation of a new, crystalline CuO·3H2O phase occurs in water vapour containing atmosphere, which can result in catalyst deactivation. However, this effect is fully reversible and the catalyst is able to replenish initial activity in dry atmosphere. Potentiality of CuO/CeO2 materials in catalytic N2O decomposition in industrial processes was confirmed by long-term stability tests performed in the period of 50 h in the presence of inhibiting gas components.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Matériaux poreux, Porous materials, Composé binaire, Binary compound, Compuesto binario, Matériau poreux, Porous material, Material poroso, Acide fluoroborique, Fluoroboric acid, Fluorobórico ácido, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur sur support, Supported catalyst, Catalizador sobre soporte, Mésoporosité, Mesoporosity, Mesoporosidad, Nanoparticule, Nanoparticle, Nanopartícula, Silice, Silica, Sílice, Sonication, Sonicación, Sonochimie, Sonochemistry, Sonoquímica, Support catalyseur, Catalyst support, Soporte catalizador, Synthèse, Synthesis, Síntesis, Ultrason, Ultrasound, Ultrasonido, SiO2, Mesoporous silica nanoparticles, Pyrroloacridinones, Sonication mediated synthesis, and Supported HBF4 catalyst

Fluoroboric acid (HBF4) adsorbed on mesoporous silica nanoparticles of 600 nm dimension was synthesized and characterized by N2 adsorption, HRTEM, EDX, XPS. The applicability of silica-HBF4 was probed through the sonication assisted synthesis of pyrroloacridinones in ecofriendly solvent ethanol. Standard leaching experiment was performed to show that the reaction was heterogeneous with this recyclable catalyst.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé binaire, Binary compound, Compuesto binario, Composé de métal de transition, Transition element compounds, Acide, Acids, Acido, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur sur support, Supported catalyst, Catalizador sobre soporte, Composé de lanthanide, Lanthanide compound, Lantánido compuesto, Hydrogénation, Hydrogenation, Hidrogenación, Oxyde de cérium, Cerium oxide, Cerio óxido, Oxyde de zirconium, Zirconium oxide, Zirconio óxido, Phase liquide, Liquid phase, Fase líquida, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réduction chimique, Chemical reduction, Reducción química, Solution solide, Solid solution, Solución sólida, CeO2, ZrO2, CeO2-ZrO2 solid solutions, Liquid-phase catalytic hydrogenation, Simultaneous reduction of monochloroacetic acid and bromate, and Supported Pd catalysts

Palladium catalysts supported on ZrO2, CeO2 and CeO2-ZrO2 solid solutions were prepared using the deposition-precipitation method, and individual and simultaneous reduction of monochloroacetic acid (MCAA) and bromate by liquid-phase catalytic hydrogenation on these catalysts was investigated. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction, measurement of point of zero charge, X-ray photoelectron spectroscopy and CO chemisorption. Characterization results showed that CeO2-ZrO2 solid solutions with varied Ce/Zr ratios had nearly identical points of zero charge to those of ZrO2 and CeO2. For supported Pd catalysts, the binding energy of Pd 3d5/2 of Pd/CeO2 was found to be higher than that of Pd/ZrO2, indicative of a stronger metal-support interaction in the former. Given a similar Pd loading, Pd dispersion of Pd/Ce1-xZrxO2 first increased and then decreased with CeO2 content, and the highest Pd dispersion was observed on Pd(0.86)/Ce0.8Zr0.2O2. Accordingly, Pd/Ce1-xZrxO2 exhibited much higher catalytic activities than Pd/ZrO2 at a Pd loading amount of around 0.85 wt.%, and the highest activity was identified on Pd(0.86)/Ce0.8Zr0.2O2 for individual reduction of bromate and MCAA. The turnover frequencies of Pd(0.86)/Ce0.8Zr0.2O2 for the reduction of bromate and MCAA were 0.69 and 0.23 s-1, respectively, which were one order of magnitude higher than the supported Pd catalysts previously reported. For the simultaneous reduction of MCAA and bromate, the presence of bromate completely suppressed MCAA reduction on Pd(0.85)/ZrO2, while both MCAA and bromate could be effectively reduced on Pd(0.86)/Ce0.8Zr0.2O2. Additionally, the simultaneous reduction of bromate and MCAA proceeded via a competitive reaction mechanism, and the reduction rate of bromate or MCAA was negatively correlated to the competitor concentration.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Electrochimie, Electrochemistry, Photoélectrochimie. Electrochimiluminescence, Photoelectrochemistry. Electrochemiluminescence, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dopage, Doping, Graphite, Grafito, In situ, Nanostructure, Nanoestructura, Nitrure de carbone, Carbon nitrides, Photocatalyse, Photocatalysis, Fotocatálisis, Photoélectrochimie, Photoelectrochemistry, Fotoelectroquímica, Protection environnement, Environmental protection, Protección medio ambiente, Nanofeuillet, Nanosheet, Graphite-like carbon nitride, Heterojunction, Mott-Schottky effect, and Nanosheets

A novel mesoporous ternary photocatalyst consisting of g-C3N4 nanosheets, metallic silver and MoS2 nanosheets is prepared using AgNO3 as a multifunctional modifier during thermal polymerization of melamine and few-layer MoS2 in a simple one-pot process. The gas bubbles from AgNO3 form an extra soft templates to in situ alter the polymerization behavior of melamine, creating thin g-C3N4 nanosheets and large porous structure that exhibit enhanced light absorption. The solution-based, soft-chemical synthesis enables homogeneous inclusion of metallic silver in the g-C3N4 nanosheets and high dispersibility of ultrathin MoS2 nanosheets in the obtained nanocomposite. In situ coupling between metallic silver and g-C3N4 nanosheets produces nanoscale Mott-Schottky effect, provides an effective channel for charge separation and transfer, and tunes energy band of the latter. More importantly, modulated energy band of g-C3N4 nanosheets synergistically expedites the separation and transfer of photogenerated electron-hole pairs at the interface of two-dimensional g-C3N4/MoS2 heterojunction. As a result, the ternary nanocomposite exhibits improved photoelectrochemical performance and photocatalytic activity under simulated sunlight irradiation compared with other reference materials. Our results provide new insights into the design and large-scale production of semiconductor photocatalyst.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé binaire, Binary compound, Compuesto binario, Composé de lanthanide, Lanthanide compound, Lantánido compuesto, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Composé de métal de transition, Transition element compounds, Hydrocarbure, Hydrocarbon, Hidrocarburo, Monoxyde de carbone, Carbon monoxide, Carbono monóxido, Néodyme, Neodymium, Neodimio, Oxydation, Oxidation, Oxidación, Oxyde de cérium, Cerium oxide, Cerio óxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Suie, Soot, Hollín, Zircone, Zirconia, Zircona, CeO2, ZrO2, Ceria-zirconia catalyst, Diesel soot, Hydrocarbons, and Neodymium-ceria catalyst

Ce0.73-xZr0.27NdxO2 mixed oxides (x ≤ 0.3) were prepared, characterized by XRD, Raman spectroscopy, N2 adsorption isotherms and H2-TPR, and tested for simultaneous CO, propylene, benzene and soot oxidation in a gas mixture containing O2, NOx, H2O, CO2, CO, propylene (model aliphatic hydrocarbon) and benzene (model aromatic hydrocarbon) that simulates a diesel exhaust. Ce-Zr mixed oxide doping with a low atomic fraction of neodymium (0.01 ≤ x ≤ 0.09) promotes the creation of oxygen vacancies, has a minor effect in the BET specific surface areas of the oxides, increases the surface ceria reducibility and has a positive effect in the catalytic activity. On the contrary, higher neodymium atomic fractions (x = 0.2 and 0.3) promote sintering, with a drastic decrease of the BET specific surface area, surface reducibility and catalytic activity. The Ce0.73-xZr0.27NdxO2 catalysts with x ≤ 0.09 are able to accelerate simultaneously soot, propylene and benzene combustion, and as a general trend, the catalytic behavior of Ce0.73Zr0.27O2 is improved by low atomic fraction neodymium doping (0.01 ≤ x ≤ 0.09). These Ce0.73-xZr0.27NdxO2 mixed oxides with 0.01 ≤ x ≤ 0.09 are also able to accelerate CO oxidation in a certain extent, but there is a net production of CO during soot combustion because the oxidation capacity of these oxides is not high enough to oxidize all CO released as soot combustion product.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Bulle, Bubble, Ampolla, Gaz, Gases, Gas, Radical libre, Free radical, Simulation ordinateur, Computer simulation, Simulación computadora, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Computer simulations, OH radical, Saturating gas, Single-bubble sonochemistry, and Ultrasonic frequency

Central events of ultrasonic action are the bubbles of cavitation that can be considered as powered microreactors within which high-energy chemistry occurs. This work presents the results of a comprehensive numerical assessment of frequency and saturating gases effects on single bubble sonochemistry. Computer simulations of chemical reactions occurring inside a bubble oscillating in liquid water irradiated by an ultrasonic wave have been performed for a wide range of ultrasonic frequencies (213-1100 kHz) under different saturating gases (O2, air, N2 and H2). For O2 and H2 bubbles, reactions mechanism consisting in 25 reversible chemical reactions were proposed for studying the internal bubble-chemistry whereas 73 reversible reactions were taken into account for air and N2 bubbles. The numerical simulations have indicated that radicals such as ·OH, H·, HO2· and O are created in the bubble during the strong collapse. In all cases, hydroxyl radical (·OH) is the main oxidant created in the bubble. The production rate of the oxidants decreases as the driving ultrasonic frequency increases. The production rate of ·OH radical followed the order O2 > air > N2 > H2 and the order becomes more remarkable at higher ultrasonic frequencies. The effect of ultrasonic frequency on single bubble sonochemistry was attributed to its significant impact on the cavitation process whereas the effects of gases were attributed to the nature of the chemistry produced in the bubble at the strong collapse. It was concluded that, in addition to the gas solubility, the nature of the internal bubble chemistry is another parameter of a paramount importance that controls the overall sonochemical activity in aqueous solutions.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie de surface, Surface physical chemistry, Echange d'ions, Ion-exchange, Zéolites: préparations et propriétés, Zeolites: preparations and properties, Atmosphère, Atmosphere, Atmósfera, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Combustion, Combustión, Monoxyde de carbone, Carbon monoxide, Carbono monóxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Zéolite ZSM5, Catalytic activity, Cu-Ce/ZSM-5, and Self-sustained combustion

The Cu/ZSM-5, Ce/ZSM-5 and Cu-Ce/ZSM-5 catalysts were prepared and characterized in this investigation and the catalytic activity of carbon monoxide (CO) combustion under these catalysts was determined by temperature-programmed oxidation. The activity for the CO combustion follows the decreasing order: Cu-Ce/ZSM-5 > Cu/ZSM-5 > Ce/ZSM-5, indicated by lower ignition, light-off, extinction temperature and broader hysteresis determined via both heating and cooling feeding process. The CO adsorbed on the copper sites to form Cu+-CO complexes, monodentate and bidentate carbonates was considered to be the crucial step for CO catalytic combustion. At the CO concentration ≥5 vol.%, the CO self-sustained combustion was achieved over the Cu-Ce/ZSM-5 catalyst. One reason is due to formation of Cu2+ ions incorporated into cerium oxides, which are more reducible than the copper clusters, minicrystals and bulk CuO particles. Another reason is attributable to the formation of Ce4+/Ce3+ redox couple, which facilitates oxygen transport on the catalyst surface.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dépôt, Deposition, Depósito, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Dissociation de l'eau, Water splitting, BiOCl, Photo-deposition, Photocatalytic, and Selective transport

The efficient spatial transport of photo-generated electrons and holes to different facets is critical to construct an efficient solar energy conversion system. BiOCl@Au/MnOx hierarchical structure was fabricated by depositing the Au and MnOx on the {0 0 1} and {1 1 0} crystal facets of BiOCl, respectively. The internal electric field (EIEF) along the 〈0 0 1〉 direct, and strong local electric field (ELEF) induced by the fast formed Au nanoparticles have been proposed as the intrinsic driving force for the spatial separation and transport of charge carriers in the BiOCl semiconductor, which resulted in significant enhancement of solar-driven photocatalytic activity for the pure water splitting without any sacrificial agent. The special structure of selective deposition of redox cocatalysts on the different facets of a single crystal should be promising and intriguing for designing highly efficient solar energy conversion photocatalyst.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Acide carboxylique, Carboxylic acid, Acido carboxílico, Composé de métal de transition, Transition element compounds, Acide formique, Formic acid, Fórmico ácido, Alliage, Alloys, Aleación, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Décomposition, Decomposition, Descomposición, Electrofilage, Electrospinning, Electrohilado, Hydrogène, Hydrogen, Hidrógeno, Nanofibre, Nanofiber, Nanofibra, Nanoparticule, Nanoparticle, Nanopartícula, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Résonance plasmon surface, Surface plasmon resonance, AuPd alloy, and Formic acid decomposition

We present high-yield hydrogen production through selective photocatalytic decomposition of formic acid by using electrospun TiO2 nanofibers decorated with AuPd bimetallic alloy nanoparticles under simulated sunlight irradiation. By using only 5 mg of the AuPd/TiO2 nanofibers containing the 0.75% Au and 0.25% Pd, we could achieve an optimal H2 generation rate of 88.5 μmol h-1 with an apparent quantum yield at 365 nm as 15.6%. which is higher than that of the Pd/TiO2 and Au/TiO2 nanofibers by a factor of 1.6 and 4.5, respectively. The enhanced photocatalytic decomposition of formic acid for H2 generation could be attributed to the stronger electron-sink effect of AuPd alloy nanoparticles, the high selectivity of Pd for the dehydrogenation of formic acid, and the surface plasmon resonance effect of Au. More importantly, we demonstrate that the photocatalytic processes enable re-activation of the AuPd nanoparticles that were poisoned by CO during thermal decomposition of formic acid. As such, the presented AuPd/TiO2 nanofibers are promising materials for re-generation of H2 under mild conditions from liquid storage carrier of hydrogen. .

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Métal transition, Transition metal, Metal transición, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Dopage, Doping, Méthanation, Methanation, Metanación, Nickel, Niquel, Platine, Platinum, Platino, Protection environnement, Environmental protection, Protección medio ambiente, Smectite, Esmectita, CO removal, Platinum doping, and Selective methanation

The selective methanation of CO in a H2-rich gas stream has been investigated with nickel catalysts including synthetic nickel-containing smectite (SM(Ni)) catalysts undoped and doped with platinum in small quantities and conventional nickel catalysts on SiO2, Al2O3, ZrO2, and MgO. The nickel content in SM(Ni) and the nickel loading in the other catalysts were the same, being 35wt.%. The CO conversion with SM(Ni) was smaller than those with the conventional supported nickel catalysts at temperatures of 150-300°C. However, the former showed the higher selectivity to the methanation of CO of >95% at 250°C or below compared to the latter catalysts. The low activity of SM(Ni) was ascribed to a small area of exposed nickel species. The area of exposed nickel species was improved by doping a reduction promoter of platinum to SM(Ni), resulting in an increase in the activity while keeping the high selectivity to the CO methanation. The influence of reduction temperature and platinum loading on the activity and selectivity was investigated.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Oxygène, Oxygen, Oxígeno, Phosphate de zirconium, Zirconium phosphate, Zirconio fosfato, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réduction chimique, Chemical reduction, Reducción química, Solide, Solid, Sólido, Ce0.75Zr0.25O2, Lattice oxygen, and NH3-SCR

A zirconium phosphate @ Ce0.75Zr0.25O2 (ZP/CZ) catalyst was synthesized by impregnating zirconium phosphates on Ce0.75Zr0.25O2 microspheres. Catalysts with different structures were also synthesized by various methods to illustrate the structure advantage of ZP/CZ catalyst in selective catalytic reduction of NOx by ammonia (NH3-SCR). The catalysts were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), BET surface area, Infrared (IR) spectra, Ultraviolet-visible (UV-vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (TPR) and diffuse reflectance infrared Fourier transformed spectra (DRIFTS) of NH3/NOx adsorption. ZP/CZ catalyst presents excellent catalytic activity at 250-450 °C with a good N2 selectivity under high space velocity of 300,000 h-1. Firstly, the zirconium phosphate provides adsorption sites for ammonia on the surface of the catalyst and the cerium sites in the core act as the redox sites for NO oxidation. The pre-combination of zirconium and phosphate can reduce the strong interactions between phosphates and cerium ions. Therefore, the mobility of surface lattice oxygen on Ce0.75Zr0.25O2 catalyst is retained, which is essential to obtain a catalyst with high NH3-SCR activity at low temperatures. Moreover, NH4NO3 has proved to be an important intermediate for the NH3-SCR reaction on the surface of ceria based catalysts. The ZP/CZ catalyst preserves plenty of oxygen vacancies, facilitating the Ce4+ → Ce3+ redox circles and therefore promotes the nitrites/nitrates formation and desorption on catalyst. Two distinct adsorption sites for NH3 and NO, result in a close contact between ads-NH3/NH4+ and ads-NO3-/NO2- species on ZP/CZ catalyst, which can react with NO rapidly with the participation of active surface lattice oxygen.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Autoassemblage, Self assembly, Autoensamble, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dégradation photochimique, Photochemical degradation, Degradación fotoquímica, Nanoparticule, Nanoparticle, Nanopartícula, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Sulfure, Sulfides, Sulfuro, Superréseau, Superlattice, Superred, Synthèse, Synthesis, Síntesis, Cuprous sulfide, Photocatalytic degradation, Scalable synthesis, and Self-assembly

Size- and shape-tunable Cu2S nanoparticles were successfully synthesized via a facile one-pot solvothermal process and appreciable yields at gram-scale were achieved in every single reaction. By meticulous observation with a high resolution transmission electron microscope, intensively existing atomic-level superlattice structures were identified and perceived as a result of the coexistence of both chalcocite and chalcocite-M phase in as-obtained Cu2S nanoparticles. Further, 3D ordered self-assemblies of pristine Cu2S nanoparticles were obtained by introducing the polar solvent, ethanol, into the non-polar colloidal dispersion systems during the post-treatment process, and thereby the double-superlattice (DSL) nanoparticle systems consisted of both atomic- and particle-level superlattice structures were achieved. And as promising photocatalysts, although the photocatalytic activity was influenced mutually by the size, shape, crystallinity, atomic-level superlattice structures of pristine Cu2S nanoparticles and their self-assembling behavior, the novel structured DSL nanoparticle systems finally demonstrated highly enhanced photocatalytic efficiency towards the degradation of methylene blue.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Benzène(nitro), Dégradation, Degradation, Degradación, Ozonation, Ozonization, Ozonización, Ozone, Ozono, Radical hydroxyle, Hydroxyl radicals, Réaction catalytique, Catalytic reaction, Reacción catalítica, Solution aqueuse, Aqueous solution, Solución acuosa, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Catalytic ozonation, Hydroxyl radical (·OH), Multiple-field ultrasound, and Nitrobenzene

The synergetic effect between ozone and ultrasound can enhance the degradation of nitrobenzene and removal efficiency of TOC in aqueous solution, and the degradation of nitrobenzene follows the mechanism of hydroxyl radical (.OH) oxidation. Under the same total ultrasonic power input condition, the degradation rate of nitrobenzene (kNB), the volumetric mass transfer coefficient of ozone (kLa), and the initiation rate of .OH (k.OH) increases with introduction of additional ultrasonic field (1-4) in the process of ozone/ultrasound. The increasing amount of ultrasonic fields accelerates the decomposition of ozone, leading to the rapid appearance of the maximum equilibrium value and the decrease in the accumulation concentration of ozone in aqueous solution with the increasing reaction time. The increase in mass transfer of gaseous ozone dissolved into aqueous solution and the acceleration in the decomposition of ozone in aqueous solution synchronously contribute to the increase of kLa. The investigation of mechanism confirms that the increasing amount of ultrasonic fields yields the increase in cavitation activity that improves the mass transfer and decomposition of ozone, resulting in acceleration of .OH initiation, which determines the degradation of nitrobenzene in aqueous solution.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Métal transition, Transition metal, Metal transición, Argent, Silver, Plata, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dopage, Doping, Energie, Energy, Energía, Matériau hybride, Hybrid material, Material híbrido, Protection environnement, Environmental protection, Protección medio ambiente, Rayonnement solaire, Solar radiation, Radiación solar, Transfert électron, Electron transfer, Transferencia electrón, Energy level control, Organic/inorganic hybrid solar cells, Photoexcited electron transfer, and Silver doping

The photoexcited electron transfer rate represents one of the most important properties required for photovoltaic devices. However, the fabrication of solar cells with a faster electron transfer remains a technological challenge. Regulating the energy level alignment of acceptor-donor system by the incorporation of foreign ions is one of the most promising strategies to achieve this aim. Herein we demonstrate that the incorporation of silver ions into TiO2 nanocrystals results in a remarkable reduction of energy offset between the conduction band edge of acceptor and the lowest unoccupied molecular orbital of donor. In particular, the electron transfer life time was shortened from 30.2 to 18.3 ps, i.e., almost 40% faster than pure TiO2 acceptor, thus leading to a notable enhancement of power conversion efficiency by almost 38% in organic/inorganic hybrid solar cells. The reduction of the 'excess' energy offset accelerates the electron transfer, which is expected to have an important role in applications of solar energy conversion and photon detectors.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Membranes, Acide, Acids, Acido, Détection, Detection, Detección, Mitochondrie, Mitochondria, Mitocondria, Potentiel membrane, Membrane potential, Potencial membrana, Sonochimie, Sonochemistry, Sonoquímica, Thérapie, Therapy, Terapia, Ultrason, Ultrasound, Ultrasonido, 5-Aminolevulinic acid, Macrophage, Mitochondrial membrane potential, Reactive oxygen species, and Sonodynamic therapy

Reactive oxygen species (ROS) elevation and mitochondrial membrane potential (MMP) loss have been proven recently to be involved in sonodynamic therapy (SDT)-induced macrophage apoptosis and necrosis. This study aims to develop an experimental system to monitor intracellular ROS and MMP in real-time during ultrasonic irradiation in order to achieve optimal effect in SDT. Cultured THP-1 derived macrophages were incubated with 5-aminolevulinic acid (ALA), and then sonicated at different intensities. Intracellular ROS elevation and MMP loss were detected in real-time by fluorospectrophotometer using fluorescence probe DCFH-DA and jc-1, respectively. Ultrasound at low intensities (less than 0.48 W/cm2) had no influence on ROS and MMP in macrophages, whereas at an intensity of 0.48 W/cm2, ROS elevation and MMP loss were observed during ultrasonic irradiation. These effects were strongly enhanced in the presence of ALA. Quantitative analysis showed that ROS elevation and MMP loss monotonically increased with the rise of ultrasonic intensity between 0.48 and 1.16 W/cm2. SDT at 0.48 and 0.84 W/cm2 induced mainly apoptosis in THP-1 macrophages while SDT at 1.16 W/cm2 mainly cell necrosis. This study supports the validity and potential utility of real-time ROS and MMP detection as a dosimetric tool for the determination of optimal SDT.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Alcool, Alcohol, Composé benzénique, Benzenic compound, Compuesto bencénico, Composé binaire, Binary compound, Compuesto binario, Métal transition, Transition metal, Metal transición, Acide, Acids, Acido, Activation, Activación, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Chlorophénol, Chlorophenol, Clorofenol, Composé de métal de transition, Transition element compounds, Composé du chlore, Chlorine compounds, Cloro compuesto, Dégradation, Degradation, Degradación, Echelle nanométrique, Nanometer scale, Fer, Iron, Hierro, Mécanisme, Mechanism, Mecanismo, Nanofil, Nanowires, Oxyde de fer, Iron oxide, Hierro óxido, Oxygène, Oxygen, Oxígeno, Phénols, Phenols, Fenoles, Protection environnement, Environmental protection, Protección medio ambiente, Fe O, Fe2O3, 4-Chlorophenol, Degradation mechanism, Diethylenetriaminepentacetate acid, Molecular oxygen activation, and Nanoscale zero-valent iron

In this study, an environmentally benign polyaminocarboxylic ligand diethylenetriamine pentacetate (DTPA) was first used to promote the aerobic 4-chlorophenol (4-CP) degradation with Fe@Fe2O3 core-shell nanowires, and then compared with the most used counterpart ethylenediamine tetraacetate (EDTA) of poor biodegradability. Although the 4-CP removal rate in the Fe@Fe2O3/DTPA/Air system was slower owing to the preferential degradation of DTPA, the total organic carbon removal rate in the Fe@Fe2O3/DTPA/4-CP/Air system was much faster than that in the Fe@Fe2O3/EDTA/4-CP/Air system. We interestingly found that hydroxyl radicals could more easily react with DTPA to produce DTPA radicals than with EDTA to produce EDTA radicals. Ligands (DTPA or EDTA) could significantly accelerate the hydroxyl radicals production with Fe@Fe2O3, while more hydroxyl radicals were generated in the Fe@Fe2O3/DTPA/Air system. We also employed gas chromatography-mass spectrometry and ion chromatography to detect organic intermediates and chloride ions to probe the 4-chlorophenol degradation pathways, and found its degradation pathways were dependent on the reactive oxygen species generated in the different systems. This study can clarify the roles of polyaminocarboxylic ligands on the molecular oxygen activation with nanoscale zero-valent iron, and also provide a green chlorophenols removal method.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé de métal de transition, Transition element compounds, Apatite hydroxylée, Hydroxyapatite, Hidroxiapatito, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Composé du cuivre, Copper compound, Cobre compuesto, Ethane-1,2-diol, Ethylene glycol, 1,2-Etanodiol, Hydrogénation, Hydrogenation, Hidrogenación, Protection environnement, Environmental protection, Protección medio ambiente, Copper based catalysts, Dimethyl oxalate, and Methyl glycolate

Copper based hydroxyapatite (HAP) supported (Cu/HAP) catalysts are synthesized by a facile ammonia-assisted one-pot synthesis (AAOPS) method and carefully studied on the selective hydrogenation of dimethyl oxalate (DMO). The Cu/HAP catalysts exhibit different catalytic performance compared with the conventional Cu/SiO2 ones. When the reaction temperatures are set at 483 K, the optimal Cu/HAP catalyst displays relatively high and stable catalytic performance with methyl glycolate (MG) as the main product. The yield to MG can reach 70% which is the highest value on the copper based catalysts till now. When the reaction temperature is risen to 513 K, the selectivity of the catalysts swifts to the ethylene glycol (EG), and the catalytic behavior is similar to the traditional Cu/SiO2 catalysts. It was found that the copper phosphate species play important roles in stabilizing the copper particles and the Cu+ species. Also, the abundant surface hydroxy groups on the catalysts are responsible for the distinct catalytic performance of the Cu/HAP catalysts.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur mixte, Mixed catalyst, Catalizador mixto, Coprécipitation, Coprecipitation, Coprecipitación, Dépôt, Deposition, Depósito, Hydrocarbure, Hydrocarbon, Hidrocarburo, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Particule, Particle, Partícula, Protection environnement, Environmental protection, Protección medio ambiente, Précipitation, Precipitation, Precipitación, Préparation, Preparation, Preparación, Réduction chimique, Chemical reduction, Reducción química, Séquentiel, Sequential, Secuencial, Au-Ag particles, Co-precipitation, DeNOx reaction, and HC-SCR

This study emphasizes the importance of the preparation method for bimetallic Au-Ag catalysts supported on alumina in the selective reduction of NOx by hydrocarbons with gas feed compositions representative of diesel fuelled engine exhaust gas. An optimal balance between oxidative and reductive surface properties is obtained when Au and Ag are successively introduced. Significant re-dispersion processes take place when the catalyst runs at 500°C leading to a gain in activity at low temperature and ascribed to a better interaction between Au and Ag species. Co-precipitation leads to a preferential formation of intermetallic Au-Ag particles which is detrimental to the catalytic performances. Aging at 500°C leads to a significant particle sintering and a strengthening of the metallic character.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Métal transition, Transition metal, Metal transición, Argent, Silver, Plata, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dégradation, Degradation, Degradación, Déshalogénation, Dehalogenation, Deshalogenación, Eau, Water, Agua, Electrode, Electrodes, Electrodo, Nanoparticule, Nanoparticle, Nanopartícula, Polluant, Pollutant, Contaminante, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, SECM, Screen-printed electrodes, and Trichloromethane

Electrochemical abatement of volatile polychlorinated organic compounds for environmental applications represents a very attractive and feasible alternative for working at mild reaction conditions and reduced costs. We present herein the synthesis of three different sized Ag nanoparticles (NPs) and their electrocatalytic performance in the degradation of a model pollutant (trichloromethane, CHCl3) in aqueous media. Two different methodologies are used: A conventional study based on voltammetry and chronoamperometry and a novel screening approach based on the micropipette delivery/substrate collection (MD/SC) mode of the scanning electrochemical microscopy (SECM). This new approach allows to dose any reactant, in this case CHCl3, even if the latter cannot be electrogenerated. Moreover, we introduce here a novel platform for studying nanomaterials by reducing the current collector background contribution using disposable screen-printed array electrodes. The performance ranking obtained by the SECM for the three different samples of Ag NPs synthesized is validated by its comparison with the results obtained by chronoamperometry, which demonstrates the feasibility and the good sensitivity of SECM in electrocatalysts screening for the CHCl3 reduction reaction. In addition, SECM allows to analyze simultaneously a large number of catalysts in one single experiment under constant experimental conditions. We suggest the proper size range and the presence of abundant superficial defective sites, such as steps or kinks, as the main reasons for Ag NPs C1 exhibiting the best overall catalytic performance in trichloromethane electrochemical reduction.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Biomasse, Biomass, Biomasa, Chlorure, Chlorides, Cloruro, Dissolution, Disolución, Liquide ionique, Ionic liquid, Líquido iónico, Sonochimie, Sonochemistry, Sonoquímica, Sucre, Sugar, Azúcar, Ultrason, Ultrasound, Ultrasonido, 1 -Butyl-3-methylimidazolium chloride, Fermentable sugar, Switchgrass, and Ultrasonication

The utilization of ultrasonics to rapidly dissolve switchgrass in ionic liquid, 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) was evaluated in this work. The objective of the study focused on determining the effects of various ultrasonic conditions on the recovery of carbohydrate from biomass, lignin removal, and enzymatic hydrolysis. Dried ground switchgrass was added to ionic liquid, then sonicated at a frequency of 20 kHz. The experiments were conducted using a catenoidal horn at varying amplitudes of 96 μm, 128 μm, and 160 μm and sonication times of 2,3, and 4 min. Similarly, ground switchgrass was dissolved in ionic liquid assisted by conventional heat treatment at 130 °C for 12 and 24 h. The results showed good delignification results of 53% for the 24 h heat pretreated samples and of 50.8% for ultrasonic assisted samples at 160 μm amplitude and 4 min. Even in the presence of lignin in the recovered biopolymer, both of heat treated and ultrasonicated samples obtained 100% glucan digestibility after only 3 h of enzymatic hydrolysis. Heat pretreated samples exhibited 44-59% lower xylan digestibility compared to ultrasonic pretreated samples (160 μm amplitude and 4 min sonication time). Scanning electron microscope images displayed significant changes in biomass structure from intact and crystalline of the untreated biomass to disintegrated and amorphous of the treated biomass (heat treated and ultrasonicated). With increasing ultrasonic amplitude the carbohydrate recovery decreased. Also, more than 50% of the hemicellulose fraction was lost during biomass recovery. Overall, it was concluded that ultrasonication was a promising technology to enhance dissolution of lignocellulose in ionic liquid.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Dérivé du pyrazole, Pyrazole derivatives, Pirazol derivado, Proline, Prolina, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réaction one pot, One pot reaction, Reacción one pot, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Multi-component reaction, One-pot synthesis, Spiropyranopyrazoles, and Ultrasound irradiation

A rapid and efficient ultrasound-promoted one-pot synthesis of spiro[indoline-3,4'-pyrano[2,3-c]pyrazole] derivatives is described here. The reaction of substituted phenylhydrazine and dialkyl acetylenedicarboxylate with substituted isatin and malononitrile is catalyzed by L-proline to give good-to-excellent yields in water/ethanol (v/v, 1:1) at room temperature.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé binaire, Binary compound, Compuesto binario, Composé de lanthanide, Lanthanide compound, Lantánido compuesto, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Oxyde de cérium, Cerium oxide, Cerio óxido, Protection environnement, Environmental protection, Protección medio ambiente, Réduction chimique, Chemical reduction, Reducción química, Stockage, Storage, Almacenamiento, CeO2, Ceria, Doped ceria, NOx storage reduction, Praseodymium, and Pt-ceria interaction

Model Pt/Ce0.9Pr0.1O2 and Pt/CeO2 NOx storage-reduction catalysts were prepared via nitrate calcination, co-precipitation and carbon-templating routes. Raman spectroscopic data obtained on the catalysts indicated that the introduction of praseodymium into the ceria lattice increased the concentration of defect sites (vacancies), arising from the higher reducibility of the Pr4+ cation compared to Ce4+. For the Pr-promoted samples, H2-TPR profiles contained high temperature bulk reduction peaks which were less pronounced compared with their ceria analogs, indicating that the presence of praseodymium enhances oxygen mobility due to the creation of lattice defects. Under lean-rich cycling conditions, the cycle-averaged NOx conversion of the Pt/Ce0.9Pr0.1O2 samples was in each case substantially higher than that of the Pt/CeO2 analog, amounting to a difference of 10-15% in the absolute NOx conversion in some cases. According to DRIFTS data, a double role can be assigned to Pr doping; on the one hand, Pr accelerates the oxidation of adsorbed NO, species during the lean periods. On the other hand, Pr doping destabilizes the adsorbed NO, species during the rich periods, and the kinetics of nitrate decomposition are faster on Pt/Ce0.9Pr0.1O2, leading to improved catalyst regeneration. These results suggest that ceria-based mixed oxides incorporating Pr are promising materials for NO, storage-reduction catalysts intended for low temperature operation.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé de métal de transition, Transition element compounds, Métal transition, Transition metal, Metal transición, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Oxydation, Oxidation, Oxidación, Oxyde de titane, Titanium oxide, Titanio óxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Vanadium, Vanadio, Ce/TiO2 catalyst, NH3, SO2, and Selective catalytic oxidation

The promotional effect of vanadium on Ce/TiO2 catalyst for the selective catalytic oxidation of NH3 to N2 was investigated. The catalytic activity and SO2 tolerance of 10wt% Ce/TiO2 catalyst were greatly enhanced by the addition of 2 wt% vanadium, in the temperature range of 250-350 °C. The NH3 conversion of 10wt% Ce/TiO2 had been highly enhanced from 50 to 90% at 300 °C, after vanadium addition. The BET and XPS results indicated that the addition of vanadium could result in better dispersion of Ce4+ species on TiO2, leading to the enhancement of BET surface area. H2 temperature programmed reduction (TPR) results suggest that vanadium enhances the redox properties, and the absence of bulk CeO2 in high temperature (700 C) peak indicates it could be attributed to the strong interactions among CeOx, VOx, and TiOx. More importantly, 10 wt% Ce/2 wt% V/TiO2 catalyst showed strong resistance to SO2 poisoning. DRIFT results suggest that the 10wt% Ce/2 wt% V/TiO2 catalyst could reduce the formation of NH4HSO4 species, which was beneficial for easy decomposition, in the presence of SO2. In summary, these results indicated that the 10 wt% Ce/2 wt% V/TiO2 catalyst greatly improved SCO activity and SO2 tolerance.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Composé de métal de transition, Transition element compounds, Acide, Acids, Acido, Aldéhyde, Aldehyde, Aldehído, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Rayonnement solaire, Solar radiation, Radiación solar, Solution aqueuse, Aqueous solution, Solución acuosa, Picolinic acid, Pyridinecarboxy aldehydes, Sacrificial photocatalysis, Solar chemical productions, and Vitamin 83

The conversion of pyridinemethanol isomers into their respective aldehydes and carboxylic acids has been attempted in aqueous solution through sacrificial TiO2 photocatalysis in the presence of cupric ions, at ambient temperature, under acidic and deaerated conditions, using artificial sunlight. The presence of a nitrogen atom in the aromatic ring, with respect to benzylic alcohol and its derivatives, affects the photocatalytic behavior of the substrate. The influence of both pH and temperature has also been investigated. The position of the methanolic group on the aromatic ring leads to slight changes in the selectivities, yields and the oxidation rates. Under the adopted conditions, the yields and selectivities to aldehydes are always higher than those of the respective carboxylic acids. The photocatalytic process can be carried out in consecutive copper reduction/oxidation steps in order to reuse the catalyst. In this way greater yields and selectivities to the desired product than 60% can be achieved. The process can be considered interesting as it concerns the eco-green production of valuable fine chemicals, using water as a solvent at ambient conditions, a cheap heterogeneous catalyst and solar radiation.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Electrochimie, Electrochemistry, Cinétique et mécanisme des réactions, Kinetics and mechanism of reactions, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Eau, Water, Agua, Electrocatalyse, Electrocatalysis, Electrocatálisis, Electrolyse, Electrolysis, Electrólisis, Nanotube carbone, Carbon nanotubes, Oxygène, Oxygen, Oxígeno, Protection environnement, Environmental protection, Protección medio ambiente, Dissociation de l'eau, Water splitting, Electron tunneling effect, Oxygen evolution reaction, Volcano curve, and Water electrolysis

Oxygen evolution reaction (OER) is one of the most important reactions in electrochemical energy storage and conversion systems. Thus, the development of efficient electrocatalysts with high activity and durability is of great technological and scientific significance. We demonstrate here for the first time that pristine carbon nanotubes (CNTs) composed of between 2 and 7 concentric tubes and an outer diameter of 2-5 nm have an outstanding activity for the OER in alkaline solution as compared with single-walled and multi-walled CNTs (SWNTs & MWNTs). For example, current density measured at 1.8 V (vs RHE) for the OER on triple-walled CNTs is 56 mA cm-2, ∼10 times higher than 5.9 mA cm-2 measured on SWNTs and 35 times higher than 1.6 mA cm-2 measured on MWNTs. The activity of such CNTs is significantly higher than that of conventional 20% Ru/C and 50% Pt/C electrocatalysts at high polarization potentials. Such CNTs also show an excellent stability toward OER. One hypothesis is that for the OER on CNTs with specific number of walls, efficient electron transfer occurs on the inner tubes of the CNTs most likely through electron tunneling between outer wall and inner tubes, significantly promoting the charge transfer reaction of OER at the surface of outer wall of the CNTs. For SWNTs, such separation of functionality for OER is not possible, while effective electron tunneling between outer wall and inner tubes of the CNTs diminishes as the number of walls increases due to the reduced dc bias (i.e., the driving force) across the walls or layers of MWNTs. This hypothesis is strongly supported by the observed distinctive volcano-type dependence of the electrocatalytic activity and turnover frequencies (TOF) of CNTs as a function of number of walls.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Cristal cubique, Cubic crystals, Cristal cúbico, Préparation, Preparation, Preparación, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Cubic crystal, Sb2O3, Ultrafine, and Ultrasonic

The processes and conditions for ultrasonic preparation of cubic Sb2O3 crystals under ultrasonic by neutralizing Sb4O5Cl2 with ammonium hydroxide were researched. The effects of ultrasonic power, time and temperature as well as ratio of Sb4O5Cl2 to water on the crystal form and particle size of Sb2O3 were investigated by X-ray diffraction, scanning electron microscopy and laser particle size analyzer. Cubic Sb2O3 crystals were prepared by being sonicated at 100W and 20 °C for 30 min. The particles were cubic-like, with the average size of 0.777 μm.