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ENGINEERING, MULTIDISCIPLINARY, Termogravimetría, pirolisis, cinética, mezclas de carbón, Thermogravimetry, pyrolysis, kinetics, and coal blends

Thermogravimetric characteristics and pyrolysis kinetics of coal blends were investigated using a thermogravimetric analyser under heating rate of 20°C/min, from room temperature to 850°C. Original coal samples were obtained from three Colombian regions: Valle del Cauca, South West (VAL), Antioquia, West Midlands (ANT) and Cundinamarca, Midlands (CUN). Coal blend samples (50-50 % w/w) were obtained from original coal of these three regions. The weight loss curves of coals obtained by thermogravimetry (TG) showed different trends. These may indicate that pyrolysis behaviours were not similar due to coal molecular structures have different chemical bonds. In addition, a kinetic analysis was performed to fit TG data. In the analysis, it was assumed that a single chemical reaction described the pyrolysis of coals and coal blends. A Synergy Activation Energy Ratio (SAER) was defined in order to determine an additive effect between coals and coal blends, during pyrolysis. Obtained results showed that the SAER of the CUN-VAL coal blend is close to the unit, meaning that the blend has an additive behaviour. However, the SAER of ANT-VAL coal blend is lower than one, whereas of the ANT-CUN coal blend is higher than one. It suggests that VAL and CUN coals may have a non-additive reaction when they are blended with ANT coal.
Las características termogravimétricas y la cinética de la pirolisis de mezclas de carbones se investigaron usando un analizador termogravimétrico con velocidades de calentamiento de 20°C/min desde temperatura ambiente hasta 850°C. Las muestras de carbones originales se obtuvieron de tres regiones colombianas: Valle del Cauca (VAL), Antioquia (ANT) y Cundinamarca (CUN). Las muestras de carbones mezclados (50-50 % p/p) se produjeron a partir de carbones originales de esas tres regiones. Las curvas de pérdida de peso de los carbones obtenidas por termogravimetría (TG) mostraron diferentes tendencias. Esas curvas podrían indicar que los comportamientos durante la pirólisis no fueron similares debido a que las estructuras moleculares de los carbones tienen diferentes enlaces químicos. Además, un análisis cinético se realizó para ajustar los datos de TG. En el análisis, se supuso que una reacción química única describe la pirólisis de carbones originales y mezcla de carbones. Una relación de Sinergia de Energía de Activación (SAER) se definió con el fin de determinar el efecto aditivo entre los carbones y la mezcla de carbones durante la pirólisis. Los resultados obtenidos mostraron que la SAER de la mezcla CUN-VAL está cerca de la unidad, lo que significa que la mezcla tiene un comportamiento aditivo. Sin embargo, el SAER de la mezcla ANT-VAL es inferior a uno, mientras que de la mezcla ANT-CUN es mayor que uno. Esto sugiere que los carbones VAL y CUN podrían tener una reacción no aditiva cuando se mezclan con el carbón ANT.

Mechanical engineering, Génie mécanique, Science technology, industry, Sciences et technologies, industries, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie de surface, Surface physical chemistry, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Chlorophénol, Chlorophenol, Clorofenol, Cinétique, Kinetics, Cinética, Oxyde de silicium, Silicon oxides, Oxygène, Oxygen, Oxígeno, Photooxydation, Photooxidation, Fotooxidación, Piégeage, Trapping, Captura, Porphyrine, Porphyrin, Porfirina, Rayonnement visible, Visible radiation, Radiación visible, Réaction bimoléculaire, Bimolecular reaction, Reacción bimolecular, Réaction surface, Surface reaction, Reacción superficie, Résonance paramagnétique électronique, Electron paramagnetic resonance, Resonancia paramagnética electrónica, Silice, Silica, Sílice, Solution aqueuse, Aqueous solution, Solución acuosa, 4-chlorophenol, kinetic langmuir-hinshelwood, photooxidation, porphyrin, silica, and singlet oxygen

The photooxidation of 4-chlorophenol by singlet oxygen was studied in aqueous solution. The reactions were carried in a heterogeneous system using tetra(4-carboxyphenyl)porphyrin as a sensitizer adsorbed on silicon dioxide (TcPPH/SiO2). The generation of singlet oxygen produced during photosensitization of TcPPH/SiO2 with visible light was analyzed by electron paramagnetic resonance (EPR) studies using spin trapping technique. Hydroquinone and benzoquinone were identified by HPLC as the main products of the photooxidation. The photooxidation of 4-chlorophenol followed a global kinetic Langmuir-Hinshelwood.

Mechanical engineering, Génie mécanique, Science technology, industry, Sciences et technologies, industries, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Genie chimique, Chemical engineering, Agitation, Mixing, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biotechnologie, Biotechnology, Méthodes. Procédés. Technologies, Methods. Procedures. Technologies, Génie microbiologique. Technologies des fermentations et des cultures microbiennes, Microbial engineering. Fermentation and microbial culture technology, Méthodes et appareillages divers, Various methods and equipments, Bioréacteurs, Bioreactors, Applications et implications industrielles. Aspects économiques, Industrial applications and implications. Economical aspects, Energie, Energy, Production de biocombustibles, Biofuel production, Bactérie, Bacteria, Clostridiaceae, Clostridiales, Agitation mécanique, Stirring, Agitación mecánica, Analyse sensibilité, Sensitivity analysis, Análisis sensibilidad, Appareil agité, Stirred vessel, Aparato agitado, Biocarburant, Biofuel, Biocarburante, Butanol, Cinétique, Kinetics, Cinética, Clostridium saccharoperbutylacetonicum, Cycle Embden Meyerhof, Embden Meyerhof cycle, Ciclo Embden Meyerhof, Effet concentration, Concentration effect, Efecto concentración, Fermentation, Fermentación, Modélisation, Modeling, Modelización, Optimisation, Optimization, Optimización, Productivité, Productivity, Productividad, ABE fermentation, Biobutanol, Clostridium saccharoperbutylacetonicum N1-4 ATCC13564, and Embden-Meyerhof-Parnas (EMP)

The conditions and characteristics of biobutanol production in ABE fermentation were studied. A cell growth kinetic model structured according to the proposed metabolic pathway Embden-Meyerhof Parnas (EMP) pathway for the Clostridium Saccharoperbutylacetonicum N1-4 ATCC13564 reaction scheme was used in a continuous flow stirred tank. A sensitivity analysis and optimization based on the decision variables butanol productivity, glucose to butanol yield and glucose global conversion for different feed concentrations and dilution rate were performance. Productivity values of 27,46 mM h-1, yield of 0,65 mmol of butanol per mmol of glucose and final conversion of 95,38% at optimal food concentration of 295 mM and optimal final dilution rate of 0,15 h-1 were obtained.

ENGINEERING, MULTIDISCIPLINARY, dichloromethane, chloroform, tetrachloroethylene, alumina, titanium, sol-gel, kinetic, palladium, hidrodecloración, diclorometano, cloroformo, tetracloroetileno, alúmina, titania, cinética, and paladio

Se determinaron los parámetros cinéticos (velocidades de reacción, constantes de velocidad de reacción, órdenes de reacción y energías de activación) para la hidrodecloración de diclorometano en presencia de trazas de cloroformo y tetracloroetileno con catalizadores de Pd (cargas entre 0,3-0,8%) soportados en alúmina comercial y en titania preparada por el método sol-gel. Se usó un reactor diferencial de lecho fijo y temperaturas entre 100-200 ºC. La actividad aumentó con la carga de paladio. La presencia de cloroformo y de tetracloroetileno inhibió la reacción de hidrodecloración de diclorometano, lo que se refleja en la disminución de los parámetros cinéticos analizados. Los catalizadores se caracterizaron por difracción de rayos X, adsorción de nitrógeno (BET), TGA, quimisorción y TPR.
Kinetic parameters (reaction rate constants, reaction order and activation energies) were determined for dichloromethane hydrodechlorination in the presence of chloroform and tetrachloroethylene traces (loading between 0.3-0.8%) over Pd catalysts between 100-200 ºC. Two Pd supports were used: a commercial alumina and a titania xerogel. The activity increased with palladium loading. The presence of chloroform and tetrachloroethylene inhibited dichloromethane hydrodechlorination. Catalysts were characterized by X-ray diffraction, elemental analysis, nitrogen adsorption (BET), TGA, chemisorption, TPR.

Mechanical engineering, Génie mécanique, Science technology, industry, Sciences et technologies, industries, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Appareils de production et de conversion d'énergie: énergie thermique, énergie électrique, énergie mécanique, etc, Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc, Moteurs et turbines, Engines and turbines, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biotechnologie, Biotechnology, Méthodes. Procédés. Technologies, Methods. Procedures. Technologies, Technologies enzymatiques, Enzyme engineering, Production d'enzymes, Production of selected enzymes, Préparation par synthèse chimique d'enzymes modifiées, de fragments d'enzymes et d'analogues d'enzymes, Chemical synthesis for preparing modified enzymes, enzyme fragments and enzyme analogs, Acide gras, Fatty acids, Acido graso, Alcool, Alcohol, Biocarburant, Biofuel, Biocarburante, Biodiesel, Cinétique, Kinetics, Cinética, Ethanol, Etanol, Etude expérimentale, Experimental study, Estudio experimental, Huile ricin, Castor oil, Aceite ricino, Huile végétale, Vegetable oil, Aceite vegetal, Modélisation, Modeling, Modelización, Solvant, Solvent, Solvente, Synthèse enzymatique, Enzymatic synthesis, Síntesis enzimática, Transestérification, Transesterification, Transesterificación, Ping-Pong Bi Bi mechanism, biodiesel, lipase, and transesterification

Biodiesel synthesis through transesterificación of castor oil with ethanol using n-hexane as a solvent and a lipozyme TL IM commercial lipase as a biocatalyst was studied. The effect of ethanol molar relation to oil (3:1-10:1), temperature of reaction (35-65°C), initial enzymatic charge (5-20% p/p) and amount of water (0-10% p/p) was investigated. The maximum percentage of bio-diesel (ethyl-esters) was obtained at a temperature of 35°C, a 5:1 ethanol to oil molar ratio, an initial enzymatic charge of 15 % p/p and an initial water concentration of 2% p/p, both of them based on the castor oil weight. A simplified model was proposed to describe the enzymatic kinetics of castor oil transesterification with ethanol, based on the ping-pong Bi Bi mechanism with competitive inhibition for alcohol. The kinetic parameters of the model were estimated graphically and parametrically; a good approach among the results foreseen by the model and experimental data was found at low ethanol concentration (40-80 mol Kg-1).

Mechanical engineering, Génie mécanique, Science technology, industry, Sciences et technologies, industries, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie naturelle, Natural energy, Biomasse, Biomass, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biotechnologie, Biotechnology, Méthodes. Procédés. Technologies, Methods. Procedures. Technologies, Génie microbiologique. Technologies des fermentations et des cultures microbiennes, Microbial engineering. Fermentation and microbial culture technology, Sciences medicales, Medical sciences, Pharmacologie. Traitements medicamenteux, Pharmacology. Drug treatments, Antibiotiques. Antiinfectieux. Antiparasitaires, Antibiotics. Antiinfectious agents. Antiparasitic agents, Antibactériens, Antibacterial agents, Bactérie, Bacteria, Micrococcaceae, Micrococcales, Streptococcaceae, Acide lactique, Lactic acid, Láctico ácido, Bactérie lactique, Lactic acid bacteria, Bacteria láctica, Biomasse, Biomass, Biomasa, Cinétique, Kinetics, Cinética, Consommation, Consumption, Consumo, Fermentation, Fermentación, Levure, Yeast, Levadura, Microorganisme, Microorganism, Microorganismo, Staphylococcus aureus, Streptococcus agalactiae, Weissella confusa, Antimicrobial activity, and Saphylococcus aureus

The kinetics of biomass and lactic acid production, substrate consumption, antimicrobial activity of Weissella confusa, a lactic acid bacteria with antimicrobial activity against Streptococcus agalactiae and Staphylococcus aureus, bovine-mastitis producing microorganisms, were evaluated. The fermentations were carried out anaerobically in batch using as substrate, commercial substrate (SC), milk supplemented with yeast extract (LEL) and milk supplemented with yeast extract and glucose (LELG) and the kinetic parameters were compared. The greater the inhibition of pathogens, the greater production of lactic acid and the higher yield of biomass is presented on substrate LELG. This substrate presented a diameter of inhibition of 36.33 mm for Staphylococcus aureus after the fourth hour of fermentation and 39 mm of diameter for Streptococcus agalactiae at the eighth hour of fermentation; maximum production of lactic acid was 13.12 gL-1 (at 48 h) and maximum concentration of biomass was 3.07 gL-1 (at 48 h). These results were superior to those obtained on SC where, for the same fermentation time 24.38 mm for Staphylococcus aureus and 30.58 mm diameter of inhibition for Streptococcus agalactiae were obtained; the highest lactic acid production was 11,6 gL-1 (at 12h) and the highest concentration of biomass was 1.18 gL-1 (at 24 h). The results suggest that LELG may become a low cost alternative for the production of Weissella confusa, microorganism with great potential for control and treatment of bovine mastitis.

Mechanical engineering, Génie mécanique, Science technology, industry, Sciences et technologies, industries, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Mécanismes fondamentaux et formes de la corrosion, Corrosion mechanisms, Acier, Steel, Acero, Analyse statistique, Statistical analysis, Análisis estadístico, Statistische Analyse, Cinétique, Kinetics, Cinética, Kinetik, Corrosion, Corrosión, Korrosion, Cuivre, Copper, Cobre, Kupfer, Effet impureté, Impurity effect, Efecto impureza, Begleitelementeinfluss, Essai immersion, Immersion test, Ensayo inmersión, Etude expérimentale, Experimental study, Estudio experimental, Experimentelle Untersuchung, Fusion surface, Surface melting, Fusión superficie, Oberflaechenschmelzen, Milieu corrosif, Corrosive environment, Medio corrosivo, Modèle phénoménologique, Phenomenological model, Modelo fenomenológico, Norme ASTM, ASTM standard, Norma ASTM, ASTM Norm, Schéma équivalent, Equivalent circuit, Esquema equivalente, Ersatzschaltbild, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Spectrométrie impédance électrochimique, Electrochemical impedance spectroscopy, Espectroscopia de impedancia electroquímica, Cebelcor, equivalent circuit of Warburg, rust, and weathering steel

A Cebelcor chamber was used to make immersion-emersion cyclical tests of two commercial steels (ASTM A36 and ASTM A242) and three experimental plasma arc melted steels (0.50% Ni, 0.50% Cu and 0.25% Cu+0.25%Ni). Four samples of each steel material were evaluated. Aerated 10-3 M Na2SO4 solution was employed as corrosive solution. The behaviour of each test was evaluated by means of electrochemical impedance spectroscopy technique (EIS) in situ (inside the Cebelcor chamber) for 1, 15, 30, 45, 60, and 90 days by using a frequency range between 200 Hz-0.01 Hz frequency range. At the end of the exposition the rusts were evaluated outside the Cebelcor by means of the (ex situ) EIS, but using a wide frecuency range (900 kHz-0.005Hz). The simulation of these last data by means of an equivalent circuit with Warburg diffusion impedance, showed the existence of two layers of rust, electrically different between them. The results of in situ and ex situ EIS data for 90 days exposition times indicated that exists a statistically significative difference between the ASTM A36 and the other materials, demonstrating a larger ohmic resistance of the rust of the last ones. The ASTM A36 steel showed that the rust is composed of α/γ FeOOH plus magnetite (10%). The ASTM A242 and the experimental steels with nickel, copper and combinations of both showed that the rusts are composed of α/γ FeOOH with no evidence of magnetite. A similar effect between copper and nickel in the atmospheric corrosion kinetics was found. All the parameters found in the simulation are interpreted in terms of a phenomenological model proposed for explaining the results.

Mechanical engineering, Génie mécanique, Science technology, industry, Sciences et technologies, industries, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Industries agroalimentaires, Food industries, Industries laitières et fromagères. Crèmes glacées, Milk and cheese industries. Ice creams, Fungi, Zygomycota, Activité enzymatique, Enzymatic activity, Actividad enzimática, Biomasse, Biomass, Biomasa, Carbone, Carbon, Carbono, Cinétique, Kinetics, Cinética, Culture, Cultivo, Faisabilité, Feasibility, Practicabilidad, Fermentation, Fermentación, Mucor miehei, Origine microbienne, Microbial origin, Origen microbiano, Plan expérience, Experimental design, Plan experiencia, Plan factoriel, Factorial design, Plan factorial, Productivité, Productivity, Productividad, Présure, Rennet, Cuajo, Réacteur chimique, Chemical reactor, Reactor químico, average of culture, corn flour, enzymatic activity, microbial rennet, and milk serum

The kinetics ofbiomass production and rennet from fungi Mucor miehei using culture media with alternative substrates as a source of carbon and nitrogen was studied in order to improve the enzymatic activity. An initial screening was performed in order to select the feasibility of each by-product and from these results the crossed effects of the best sources of carbon and nitrogen over enzymatic productivity were evaluated through an experimental factorial 22 design. It allowed us to propose an alternative culture media viable for the rennet production at industrial scale. The fermentations were carried out in a laboratory batch reactor, at 37° C, pH between 6.3-6.5 and 250 rpm. The best culture media was established as that which contained whey both as a source of carbon and nitrogen (media 1) and whey as a source of carbon and corn flour as a source of nitrogen (media 2). Maximum Rennet strength achieved (FC) was 1333.704 at 90 h in media 1 and 1069.71 at 85 h in media 2.