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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, 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, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Cinétique, Kinetics, Cinética, Dégradation photochimique, Photochemical degradation, Degradación fotoquímica, Isotherme adsorption, Adsorption isotherm, Isotermo adsorción, Mécanisme, Mechanism, Mecanismo, Nanomatériau, Nanostructured materials, Oxyde de titane, Titanium oxide, Titanio óxido, Phénol, Phenol, Fenol, Phénols, Phenols, Fenoles, Protection environnement, Environmental protection, Protección medio ambiente, Adsorption isotherms, Formal mechanisms, Photocatalytic degradation, and TiO2 nanomaterials

Anisotropic TiO2 nanomaterials (nanotubes, nanorods, nanoplates, nanospheres, and nanoparticles) with controlled structural and textural properties have been evaluated in the photocatalytic degradation of phenol under UV conditions. The kinetic study of phenol adsorption fits well to a quasi-second-order model whereas the adsorption isotherms of phenol over the different TiO2 nanomaterials follow the Langmuir model and the degradation kinetics the Langmuir-Hinshelwood (L-H) model. TiO2 nanomaterials exposing (001) or (101) anatase facets are less active than TiO2 P25 for the phenol degradation. This is related to their tendency to degrade faster intermediates products (organic acids) rather than phenol itself. A good compromise between anatase crystallinity, crystallites sizes, and specific surface area can however improve the photocatalytic activity of the TiO2 nanomaterials. Results also showed that the degradation mechanism follows pseudo-first order kinetics. Pseudo-rate constants were therefore determined and formal mechanism schemes 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, Composé de métal de transition, Transition element compounds, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Cinétique, Kinetics, Cinética, Colorant, Dyes, Colorante, Décoloration, Discoloration, Decoloración, Ethylène polymère, Polyethylene, Etileno polímero, Film, Película, Mécanisme, Mechanism, Mecanismo, Nettoyage, Cleaning, Limpieza, Oxyde de titane, Titanium oxide, Titanio óxido, Protection environnement, Environmental protection, Protección medio ambiente, Pulvérisation irradiation, Sputtering, Pulverización irradiación, MB self-cleaning, and PE-TiO2 surfaces

Polyethylene-TiO2 (from now on PE-TiO2) transparent, non-scattering sputtered films have been found effective in the discoloration of methylene blue (MB) under low intensity solar simulated light. By Fourier transform attenuated infrared spectroscopy (ATR-FTIR), the systematic shift and decrease in the vs(CH2) and vs(C=C) vibration-rotational bands was observed preceding MB discoloration. RF-pretreatment allowed a significant increase in the TiO2 loading on PE compared to non-pretreated PE as shown by X-ray fluorescence (XRF). The PE-TiO2 photo-switching from a hydrophobic to a hydrophilic surface was observed within 60 min under light while the reverse process was complete within 24 h in the dark. The position of the MB* and MB*/MB+ levels allowing electron injecting into the TiO2cb is discussed. The probability for the MBT deactivation and of MB* reacting with O2 leading to the short lived MB+ cation is estimated. A mechanism for MB discoloration on PE-TiO2 is suggested.

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, Métal transition, Transition metal, Metal transición, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Cinétique, Kinetics, Cinética, Fer, Iron, Hierro, Oxydation, Oxidation, Oxidación, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réduction chimique, Chemical reduction, Reducción química, Zéolite, Zeolite, Zeolita, Ammonia oxidation, Iron zeolite, Nitrogen oxides, and Selective catalytic reduction

The steady-state kinetics of the selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with ammonia over a commercial iron zeolite catalyst were studied in the temperature range of 250 to 450°C using an integral tubular reactor. Special attention was paid to the stoichiometric ratio of the conversion of ammonia and nitrogen oxides. For this purpose, both systematic SCR measurements at different feed gas compositions and independent studies of the catalytic oxidation of ammonia in the absence of NO and NO2 were carried out. Under all reaction conditions, a considerable deviation from the expected 1:1 stoichiometry was observed. The steady-state kinetics of the reacting system could be described by global Langmuir-Hinshelwood-type rate equations for standard SCR, fast SCR, NO/NO2 equilibrium and NH3 oxidation. For the correct calculation of the ammonia oxidation it was necessary to include two terms. A first one describing the reaction of NH3 with O2, which becomes important at temperatures above 400°C, and a second rate equation which is not only proportional to NH3 and O2 but also to the NO concentration and which is of particular relevance at low reaction temperatures. Additional measurements with different catalyst particle sizes including industrial extrudates could be successfully described with the aid of a reactor model which took film and pore diffusion phenomena into account.

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 sur support, Supported catalyst, Catalizador sobre soporte, Cinétique, Kinetics, Cinética, Modélisation, Modeling, Modelización, Protection environnement, Environmental protection, Protección medio ambiente, Répartition spatiale, Spatial distribution, Distribución espacial, Zéolite, Zeolite, Zeolita, Cu zeolites, Kinetic modeling, NH3 SCR, Spaci-MS, and Spatial distribution measurements

In this study, a kinetic model is developed for NH3-SCR over a honeycomb-monolith-supported Cu-zeolites using intra-catalyst axial species distribution measurements. An ammonia TPD experiment, together with micro calorimetry data were used for tuning the ammonia adsorption and desorption properties. The spatial distribution for NO oxidation, NH3 oxidation and NH3 Standard SCR were modeled between 200 and 400 °C. Four-step protocol measurements were employed in order to validate the transient functions of the model. The resulting kinetic model provides good spatiotemporal simulation of the SCR reaction and component reactions throughout the monolith catalyst system.

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, Composé de métal de transition, Transition element compounds, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Cinétique, Kinetics, Cinética, Combustible, Fuel, Hydrocarbure, Hydrocarbon, Hidrocarburo, Indium, Indio, Méthane, Methane, Metano, Nanoparticule, Nanoparticle, Nanopartícula, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Réduction chimique, Chemical reduction, Reducción química, Vapeur, Vapor, CO2 reduction, Hydrocarbon fuels, Indium doped TiO2, and Kinetic study

Indium (In)-doped titanium dioxide (TiO2) nanoparticles were synthesized using a controlled sol-gel method. The structures and properties of the catalysts were characterized by XRD, FE-SEM, TEM, XPS, BET, UV-vis and PL spectroscopy. Indium, present over the TiO2 in metal state, inhibited crystal growth and produced anatase phase of mesoporous TiO2 nanoparticles. Doping In in TiO2 also increased the surface area and enlarged the band gap. The photocatalytic activities of In-doped TiO2 nanoparticles were considerably improved for CO2 reduction with H2O vapors in a cell type photoreactor. CO was observed as the main product over TiO2, but doping In in TiO2 remarkably increased the CH4 yield. CH4 production rate over 10 wt.% In-doped TiO2 was 7.9-fold higher than the bare TiO2 at 100°C and CO2/H2O ratio of 1.43. In addition, C1-3 higher hydrocarbons namely C2H4, C2H6, C3H6 and C3H8 were detected in the product mixture. The enhanced photoactivity in mesoporous In-doped TiO2 nanoparticles can be attributed to interfacial transfer of photogenerated charges, which led to effective charge separation and inhibited recombination of photogenerated electron-hole (e-/h+) pairs. Langmuir-Hinshelwood model, developed to investigate reaction rate parameters, fitted well with the experimental data.

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, Cinétique, Kinetics, Cinética, Condition hydrothermale, Hydrothermal condition, Condición hidrotermal, Modèle cinétique, Kinetic model, Modelo cinético, Modélisation, Modeling, Modelización, Protection environnement, Environmental protection, Protección medio ambiente, Zéolite, Zeolite, Zeolita, Ammonia SCR, Cu zeolites, Cu/BEA, and Hydrothermal aging

In this study, a kinetic model describing the effect of hydrothermal aging (at 500, 600, 700, 800 and 900 °C) on Cu-zeolites is developed. The model accounts for the impact of hydrothermal aging on key reactions such as ammonia adsorption/desorption, NH3 oxidation, NO oxidation, standard SCR, rapid SCR, and NO2 SCR. In addition, a mechanism for the complex N2O formation were developed. The effect of aging on ammonia adsorption and desorption were established using micro-calorimeter data. Thereafter, an aging factor model was developed containing two aging factors, one related to over-exchanged copper sites and the other to under-exchanged copper sites. This approach worked well for ammonia and NO oxidation up to an aging temperature of 800 °C, whereas for the SCR reactions only to 700 °C. According to UV-vis, fresh and mildly aged catalysts are dominated by copper hydroxyls, while after aging at high temperature copper oxides are observed. We therefore introduce one SCR reaction associated with copper oxides, simultaneously with one SCR reaction associated with ion-exchanged Cu sites and the updated model could describe the experimental findings well. The results from the model also suggest that the standard SCR reaction is more deactivated during aging compared to SCR with NO2 present in the feed. After the 900 °C aging the BEA structure had collapsed, resulting in that several parameters in the model needed to be retuned. The results from this modeling study clearly show how complex the hydro thermal aging is over copper zeolites.

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, Antioxydant, Antioxidant, Antioxidante, Cinétique, Kinetics, Cinética, Prétraitement, Pretreatment, Pretratamiento, Sonochimie, Sonochemistry, Sonoquímica, Séchage, Drying, Secado, Ultrason, Ultrasound, Ultrasonido, Andean blackberry, Antioxidant activity, and Convective drying kinetics

In this study, we evaluated the use of ultrasound as a pretreatment for convective drying of Andean blackberry (Rubus glaucus Benth). For this, a Box-Behnken experimental design was used to study the effect of ultrasound vibration amplitude (0-90 μm), time of sonication (10-30 min) and air temperature (40-60 °C) on the retention of antioxidant compounds and on the kinetics of convective drying. The results showed that the antioxidant activity on fruit was reduced as the vibration amplitude and time of sonication increased, while was found that vibration amplitude ultrasound and air drying temperature were the variables that more affect the drying rate of blackberries. The drying rate increased by almost five times when samples were treated with ultrasound at 90 μm for 20 min. They were then dried using air at 60 °C. It is concluded that the application of ultrasound in blackberry processing allows to obtain a dehydrated product with better functional quality and shows to be effective in reducing the time necessary to achieve a given value of moisture during convective drying.

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, Electrochimie, Electrochemistry, Cinétique, Kinetics, Cinética, Electrochimie, Electrochemistry, Electroquímica, Electrolyse, Electrolysis, Electrólisis, Ibuprofène, Ibuprofen, Ibuprofeno, Oxydation, Oxidation, Oxidación, Sonochimie, Sonochemistry, Sonoquímica, Sonolyse, Sonolysis, Sonólisis, Ultrason, Ultrasound, Ultrasonido, Pseudo first-order kinetics, and Sonoelectrolysis

A hybrid advanced oxidation process combining sonochemistry (US) and electrochemistry (EC) for the batch scale degradation of ibuprofen was developed. The performance of this hybrid reactor system was evaluated by quantifying on the degradation of ibuprofen under the variation in electrolytes, frequency, applied voltage, ultrasonic power density and temperature in aqueous solutions with a platinum electrode. Among the methods examined (US, EC and US/EC), the hybrid method US/EC resulted 89.32%, 81.85% and 88.7% degradations while using NaOH, H2SO4 and deionized water (DI), respectively, with a constant electrical voltages of 30 V, an ultrasound frequency of 1000 kHz, and a power density of 100 W L-1 at 298 K in 1 h. The degradation was established to follow pseudo first order kinetics. In addition, energy consumption and energy efficiencies were also calculated. The probable mechanism for the anodic oxidation of ibuprofen at a platinum electrode was also postulated.

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, Cétone, Ketone, Cetona, Acétone, Acetone, Acetona, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Cinétique, Kinetics, Cinética, Haute fréquence, High frequency, Alta frecuencia, Oxydation, Oxidation, Oxidación, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Simulation, Simulación, Vapeur, Vapor, Controlled periodic illumination, Reaction kinetics simulation, Titanium dioxide, and UV LED

We investigated the effect of controlled periodic illumination on quantum efficiency of acetone vapor photocatalytic oxidation. It was demonstrated that quantum efficiency increases with the increase of light pulses frequency and decrease of the duty cycle and at some point reaches its maximum value which is equal to the quantum efficiency obtained under the same average photon flux. Several kinetic models were applied to the experimental data. The general conclusion was made that there are only two kinetically distinguishable active species on TiO2 surface with the lifetimes in 10-3-101 s range.

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, Accepteur électron, Electron acceptor, Aceptor electrón, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Cinétique, Kinetics, Cinética, Dégradation photochimique, Photochemical degradation, Degradación fotoquímica, Mécanisme, Mechanism, Mecanismo, Oxydant, Oxidant, Oxidante, Oxydation, Oxidation, Oxidación, Oxyde de tungstène, Tungsten oxide, Wolframio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Séparation charge, Charge separation, Separación carga, WO3, Alternative electron acceptor, Inorganic oxidant, Photocatalytic oxidation, and Visible light activity

This study evaluates the capacity of various inorganic oxidants (IO4-, HSO5-, S2O82-, H2O2, and BrO3-) to act as alternative electron acceptors for WO3-mediated photocatalytic oxidation. Combination with IO4- drastically increased the rate of photocatalytic degradation of 4-chlorophenol by WO3, while the other oxyanions only negligibly improved the photocatalytic activity. The extent of the photocatalytic performance enhancement in the presence of inorganic oxidants correlated well with the efficiencies for: (1) hydroxylation of benzoic acid as an OH• probe, (2) dechlorination of dichloroaceate as a hole scavenger, and (3) water oxidation with O2 evolution. The results suggest that the promoted charge separation primarily causes kinetic enhancement in photocatalytic degradation using the WO3/IO4- system. In marked contrast to the substrate-dependent activity of the photochemically activated IO4- (generating selective IO3•), the efficiency of the WO3/IO4- system for photocatalytic degradation did not sensitively depend on the type of target organic compound, which implies the existence of a minor contribution of the photocatalytic reduction pathway associated with the production of IO3• as a secondary oxidant. On the other hand, the insignificant inhibitory effect of methanol as an OH• quencher may reveal the possible involvement of SO4•- in the improved photocatalytic activity of the WO3/HSO5- system. The alternative use of platinized WO3, where the interfacial electron transfer occurs in a concerted step, achieved a highly accelerated photocatalytic oxidation in the presence of HSO5- and polyoxometalates as electron scavengers. In particular, the surface loading of nanoscale platinum appeared to retard the reaction route for SO4•- generation associated with a one-electron transfer.

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, Nitrile, Nitrilo, Acrylonitrile, Acrilonitrilo, Catalyse transfert phase, Phase transfer catalysis, Catálisis transferencia fase, Cinétique, Kinetics, Cinética, Polymérisation, Polymerization, Polimerización, Radical libre, Free radical, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Multi-site phase-transfer catalysis, N,N'-dihexyl-4,4'-bipyridinium dibromide, and Ultrasound irradiation

The kinetics of polymerization of acrylonitrile (AN) was carried out under heterogeneous condition using a new multi-site phase-transfer catalyst (MPTC), viz., N,N'-dihexyl-4,4'-bipyridinium dibromide in the presence of water soluble initiator, potassium peroxydisulphate (PDS) under chlorobenzene/water two phase system assisted by ultrasound irradiation at constant temperature 60 + 1 °C under nitrogen atmosphere. The rate of polymerization increases with an increasing the concentrations of AN, MPTC and PDS. The order with respect to [AN], [MPTC], and [PDS] were found to be 1.01, 1.03 and 0.52. respectively. Based on the observed results a suitable mechanism has been proposed to account for the experimental observations followed by a discussion on its significance.

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, Antioxydant, Antioxidant, Antioxidante, Cinétique, Kinetics, Cinética, Extraction, Extracción, Modèle, Models, Modelo, Modélisation, Modeling, Modelización, Sonochimie, Sonochemistry, Sonoquímica, Sous produit, By product, Subproducto, Ultrason, Ultrasound, Ultrasonido, Antioxidant capacity, Grape pomace, Total phenolic content, Ultrasound-assisted extraction, Weibull model, and Winery by-products

The kinetics of both conventional (mechanical stirring, 200 rpm) and acoustic (55 ± 5 kHz, 435 ± 5 W/L) aqueous extraction of total phenolic content and antioxidant capacity from grape pomace by-products (Vitis vinifera L.) have been experimentally evaluated and modeled at different extraction temperatures (20, 35 and 50 °C). A gradual and significant increase of total phenolic content and antioxidant capacity of the extracts was observed as the temperature increased, the highest values being obtained in the case of the extraction assisted acoustically. According to the results, the acoustic assistance of the extraction process led to aqueous extracts with phenolic and antioxidant characteristics similar to those obtained with mechanical stirring, working under lower temperature conditions and during less operating time. Specifically, the conventional extraction of total phenolics at 35 and 50 °C did not differ significantly from extractions assisted with power ultrasound at 20 and 35 °C, respectively; and the acoustic process required approximately 3, 4 and 8 times less time, at 20, 35 and 50 °C, than the conventional extraction to obtain extracts with similar characteristics. The extraction curves obtained for total phenolic content and antioxidant capacity, measured by the ABTS and FRAP methods, were properly represented by a modified Weibull model for both conventional and acoustic extractions within the temperature range 20-50 °C, presenting an average percentage of explained variance ≥ 97.9%, and an average mean relative error ≤7.0%. A high correlation (r2 ≥ 0.992) was observed between the experimental and simulated values for all the quality attributes in study.

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, Cinétique, Kinetics, Cinética, Dynamique, Dynamics, Dinámica, Réacteur, Reactor, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Bubble dynamics, Chemical kinetics, Number of bubbles, Ultrasonic frequency, and Ultrasonic reactors

Knowledge of the number of active bubbles in acoustic cavitation field is very important for the prediction of the performance of ultrasonic reactors toward most chemical processes induced by ultrasound. The literature in this field is scarce, probably due to the complicated nature of the phenomena. We introduce here a relatively simple semi-empirical method for predicting the number of active bubbles in an acoustic cavitation field. By coupling the bubble dynamics in an acoustical field with chemical kinetics occurring in the bubble during oscillation, the amount of the radical species ·OH and HO·2 and molecular H2O2 released by a single bubble was estimated. Knowing that the H2O2 measured experimentally during sonication of water comes from the recombination of hydroxyl (·OH) and perhydroxyl (HO·2) radicals in the liquid phase and assuming that in sonochemistry applications, the cavitation is transient and the bubble fragments at the first collapse, the number of bubbles formed per unit time per unit volume is then easily determined using material balances for H2O2, ·OH and HO·2 in the liquid phase. The effect of ultrasonic frequency on the number of active bubbles was examined. It was shown that increasing ultrasonic frequency leads to a substantial increase in the number of bubbles formed in the reactor.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Etudes théoriques. Données et constantes. Mesures, Theoretical studies. Data and constants. Metering, Combustion. Flammes, Combustion. Flame, Combustion des combustibles liquides, Combustion of liquid fuels, Biocarburant, Biofuel, Biocarburante, Chaîne courte, Short chain, Cadena corta, Cinétique, Kinetics, Cinética, Combustion, Combustión, Ester, Flamme laminaire, Laminar flame, Llama laminar, Oxydation, Oxidation, Oxidación, Propagation flamme, Flame propagation, Propagación llama, Acide alcanoïque ester méthyle, Acide alcanoïque ester éthyle, Alkyl esters, Ethyl esters, Laminar flames, and Methyl esters

The oxidation characteristics of several small methyl and ethyl esters with carbon number less than six were investigated in laminar flames. The kinetics of such fuels are subsets of those of larger alkyl esters that are constituents of practical biodiesel fuels. A total of seven fuels, namely methyl formate, methyl acetate, methyl propionate, methyl butanoate, ethyl formate, ethyl acetate, and ethyl propionate were considered. Experiments were conducted at atmospheric pressure, elevated reactant temperatures, and over a wide range of equivalence ratios. Laminar flame speeds were determined in the counterflow configuration in which flow velocities were measured using particle image velocimetry. Several detailed kinetic models were tested against the experimental data, and insight was provided into the high-temperature combustion kinetics of the aforementioned fuels. Based on comparisons between experimental and computed results it became apparent that the chemistry of alkyl-ester combustion chemistry is evolving and much needs to be done in order to derive improved rate constants for a wide range of elementary steps.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, 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, Cinétique, Kinetics, Cinética, Modélisation, Modeling, Modelización, Oxydation, Oxidation, Oxidación, Oxygène, Oxygen, Oxígeno, Photocatalyse, Photocatalysis, Fotocatálisis, Photochimie, Photochemistry, Fotoquímica, Photosensibilisation, Photosensitization, Fotosensibilización, Protection environnement, Environmental protection, Protección medio ambiente, Résonance, Resonance, Resonancia, Spin, Electron spin resonance, Environmental photochemistry, and Kinetic modeling

Photooxidation of Fe(II) at acidic pH occurs in photocatalytic processes of Fe(III) species, but its reaction mechanism is not well understood. The kinetics of Fe(II) oxidation in irradiated aqueous solutions at pH 3.0 have been investigated in terms of kinetic modeling approach, rate constant estimation and the significance of various oxidation pathways. Fe(II) oxidation kinetics strongly rely on the availability of UV light, Fe(III) ions and oxygen. The presence of a portion of Fe(III) in Fe(II)-containing solutions favors the rapid oxidation of Fe(II). At high concentration of Fe(II), excitation of Fe(III) species may be quenched by Fe(II) in deaerated systems or may sensitize Fe(II) oxygenation under oxic conditions. By incorporation of this photosensitization pathway, the established model in this study is shown to be able to adequately describe the oxidation of Fe(II) at pH 3.0. Sensitivity analysis indicates that photolysis of Fe(III) species is critically important for overall Fe(II) oxidation kinetics. Fe(III)-catalyzed oxygenation of Fe(II), and oxidation of Fe(II) by HO2• and •OH also exerts a marked impact on the oxidation of Fe(II). Therefore, Fe(III)-catalyzed oxygen activation and their secondary reactive oxygen species (ROS) account for the oxidation kinetics of FE(II) at acidic pH.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, 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, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Cinétique, Kinetics, Cinética, Epuration effluent gazeux, Flue gas purification, Depuración efluente gaseoso, Gaz échappement, Exhaust gas, Gas escape, Modélisation, Modeling, Modelización, Oxydation, Oxidation, Oxidación, Urée, Urea, Urées, Ureas, Zéolite, Zeolite, Zeolita, Cold start, Kinetic modeling, NO oxidation, Urea-SCR, and Zeolite catalyst

In this contribution a mathematical model suitable to simulate cold start effects over metal-promoted zeolite SCR catalysts is developed and included into an existing SCR converter model. We start from a recently published microkinetic scheme, which describes the NO2 related SCR reactions at temperatures above about 100 C on the basis of a complex reaction network, taking into account NO2 storage with formation of nitrates and their subsequent decomposition/reactivity. In order to describe material and thermal cold start effects observed from room temperature we extend such a kinetic scheme to include the low-T NO oxidation to NO2, NO2 physisorption and H2O adsorption. The rate parameters are fitted to our data from lab-scale runs analyzing each individual step. We show that the resulting model can reproduce the transient effects related to cold start both at the lab scale and in engine test bench experiments.

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, Composé binaire, Binary compound, Compuesto binario, Métal transition, Transition metal, Metal transición, Alumine, Alumina, Alúmina, Biomasse, Biomass, Biomasa, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Cinétique, Kinetics, Cinética, Or, Gold, Oro, Oxydation, Oxidation, Oxidación, Oxyde d'aluminium, Aluminium oxide, Aluminio óxido, Al2O3, Hydroxymatairesinol, and Lignans

Lignan hydroxymatairesinol (HMR) extracted from Norway spruce knots was oxidized to the lignan oxo-matairesinol (oxoMAT) in a semi-batch glass reactor under the atmospheric pressure in the presence of oxygen (5-49 vol.% in nitrogen) over 2 wt.% Au/Al2O3 catalyst, using propan-2-ol-water mixture as a solvent. The following kinetic parameters were determined: adsorption constants, rate constants, reaction order for reagents, and energy of activation. Through the parameter estimation the experimental data were fitted to the advanced kinetic model demonstrating a good correlation between the model and experiments.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, 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, Cinétique, Kinetics, Cinética, Liquide ionique, Ionic liquid, Líquido iónico, Lubrifiant, Lubricant, Lubricante, Méthode séquentielle, Sequential method, Método secuencial, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Transestérification, Transesterification, Transesterificación, Oléique acide ester méthyle, Technologie bas carbone, Bio-lubricant, and Heteropolyanion

The kinetics of ionic liquid-heteropolyanion (IL-HPA) salts catalyzed transesterification of oleic acid methyl ester (OAME) was studied via a sequential method. The method can be separated into two parts. The first part was to analyze the kinetics of transesteriifcation of OAME catalyzed by a novel catalyst and to provide a way to simulate the reaction rate profile. The second part was to verify the appropriateness of kinetic parameters calculated in the first part. Kinetic parameters were properly determined and reaction rate profiles were adequately simulated by regarding transesterification as a second order reaction. A good agreement between the experimental data and theoretically predicted values is obtained. This method may be applicable to most of three-step consecutive reaction whose tmax.firtintermediate and tmax.second intermediate at the maximum concentration are acquirable, representatively and reliably.

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 de surface, Surface physical chemistry, Matériaux adsorbants, Adsorbents, Métal transition, Transition metal, Metal transición, Biomasse, Biomass, Biomasa, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur sur support, Supported catalyst, Catalizador sobre soporte, Catalyseur, Catalyst, Catalizador, Charbon actif, Activated carbon, Carbón activado, Cinétique, Kinetics, Cinética, Mécanisme, Mechanism, Mecanismo, Or, Gold, Oro, Oxydation, Oxidation, Oxidación, Platine, Platinum, Platino, Réaction catalytique, Catalytic reaction, Reacción catalítica, Gold catalysis, and Platinum catalysis

The reaction mechanism of 5-hydroxymethylfurfural (HMF) oxidation in neutral aqueous solution with O2 to 5-hydroxymethyl-2-furancarboxylic acid (HFCA) and 2,5-furandicarboxylic acid (FDCA) was evaluated over a 3 wt% Pt/activated carbon catalyst in a semibatch reactor and confirmed that the mechanism was the same as that determined at high pH. In addition, the reaction kinetics of intermediate HFCA oxidation to FDCA over supported Pt at high pH were investigated. The combination of reaction kinetics and isotopic labeling studies using 18O-labeled H2O and O2 was used to suggest a reaction mechanism in which H2O inserts oxygen into the product and O2 scavenges electrons from the metal catalyst. Carbon nanofibers (CNF) containing excess acid or base groups were also used as supports for Pt and Au nanoparticles and evaluated as catalysts in HMF oxidation. Although the CNF-supported samples catalyzed HMF oxidation at rates similar to other carbon-supported Pt and Au catalysts, the CNF support with basic groups improved the ability of supported Au to form FDCA from HMF under mild conditions.