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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.