Photoelectrocatalytic/photoelectro-Fenton coupling system using a nanostructured photoanode for the oxidation of a textile dye: kinetics study and oxidation pathway

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A kinetics and mechanistic study of the atmospherically relevant reaction between molecular chlorine and dimethyl sulfide (DMS)

A gas-phase kinetics study of the atmospherically important reaction between Cl2 and dimethyl sulfide (DMS)Cl2 + CH3SCH3 → productshas been made using a flow-tube interfaced to a photoelectron spectrometer. The rate constant for this reaction has been measured at 1.6 and 3.0 torr at T = (294 ± 2) K as (3.4 ± 0.7) × 10−14 cm3 molecule−1 s−1. Reaction (1) has been found to proceed via an intermediate, (CH3)2SCl2, to give CH3SCH2Cl and HCl as the products. The mechanism of this reaction and the structure of the intermediate were investigated using electronic structure calculations. A comparison of the mechanisms of the reactions between Cl atoms and DMS, and Cl2 and DMS has been made and the relevance of the results to atmospheric chemistry is discussed.

Thermal Study in Solid State of Zn(II)-Diclofenac Complex: Behavior Kinetic of the Dehydration, Transition Phase and Thermal Decomposition

The dehydration, thermal decomposition and transition phase stage of Zn(II)-diclofenac compound were studied by simultaneous TG-DTA and DSC techniques. The TG and DSC curves of this compound were obtained with the mass of sample of 2 and 5 mg. Additionally, DSC curves were carried out in opened and closed alpha-alumina pans under static and nitrogen atmosphere. The DTA and DSC curves show that this compound possesses exothermic transition phase between 170-180 degrees C, which it is irreversible (monotropic reaction) The kinetics study of this transition phase stage was evaluated by DSC under non-isothermal conditions. The obtained data were evaluated with the isoconversional method, where the values of activation energy (E(a) / kJ mol(-1)) was plotted in function of the conversion degree (alpha). The results show that due to mass sample, different activation energies were obtained From these curves a tendency can be seen where the plots maintain the same profile for closed lids and almost run parallel to each other.

Evaluation of Decomposition Kinetics of Poly (Ether-Ether-Ketone) by Thermogravimetric Analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thermal study in solid state of Zn(II)-diclofenac complex: Behavior kinetic of dehydration, transition phase and thermal decomposition

The dehydration, thermal decomposition and transition phase stage of Zn(II)-diclofenac compoundwere studied by simultaneous TG-DTA and DSC techniques. The TG and DSC curves of this compoundwere obtained with the mass of sample of 2 and 5 mg. Additionally, DSC curves were carried out inopened and closed a-alumina pans under static and nitrogen atmosphere. The DTA and DSC curves showthat this compound possesses exothermic transition phase between 170-180 ºC, which it is irreversible(monotropic reaction). The kinetics study of this transition phase stage was evaluated by DSC undernon-isothermal conditions. The obtained data were evaluated with the isoconversional method, where thevalues of activation energy (Ea/kJmol-1) was plotted in function of the conversion degree (a). The resultsshow that due to mass sample, different activation energies were obtained. From these curves a tendencycan be seen where the plots maintain the same profile for closed lids and almost run parallel to each other.

NADH oxidase activity of rat and human liver xanthine oxidoreductase: potential role in superoxide production

J Biol Inorg Chem (2007) 12:777–787 DOI 10.1007/s00775-007-0229-7

Aproveitamento de subprodutos da industrialização do escargot

The waste in the industries of escargot processing is very big. This is composed basically of escargot meat out of the commercialization patterns and the visceras. In this context, there is a need to take advantage to the use of these sub-products. A possibility should be drying them and transforming them in a certain form to be reused. Than, the present work has the objective of studying the reutilization of the sub-products of the escargot industrialization for by means of drying process. The samples were transformed in pastes, through a domestic processor for approximately 1 minute and compacted in trays of aluminum without perforations with three different heights (5 mm, 10 mm and 15 mm). The drying was accomplished in a tray dryer with air circulation and transverse flow at a speed of 0,2 m/s and three temperature levels (70°C, 80°C and 90ºC). A drying kinetics study was accomplished for the obtained curves and for the heat and mass transfer coefficients using experimental procedures based in an experimental planning of 22 factorial type. Microbiological and physiochemical analysis were also accomplished for the in nature and the dehydrated sub-products. In the drying process, it was observed the great importance of the external resistances to the mass transfer and heat in the period of constant tax influenced by the temperature. The evaporation taxes indicated a mixed control of the mass transfer for the case of the thickest layers. As already expected, the drying constant behavior was influenced by the temperature and thickness of the medium, increasing and decreasing. The statistical analysis of the results, in agreement with the factorial planning 22, showed that the fissures, the shrinking of the transfer area and the formation of a crust on the surface might have contributed to the differences between the practical results and the linear model proposed. The temperature and the thickness influenced significantly in the answers of the studied variables: evaporation tax and drying constant. They were obtained significant statistical models and predictive ones for evaporation tax for the meat as well as for the visceras

Estudo da cinética de cristalização e de degradação de compósitos nanoestruturados de poliamida 6,6/nanotubos de carbonos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese e caracterização so polímero supramolecular à base de óleo de semente de mamão (Carica papaya L.) maleinizado-meglumina

Pós-graduação em Química - IQ

Quantificação da desintegração de comprimidos por fluxo ótico em seqüências de imagens de biosusceptometria AC

AC Biosusceptometry (ACB) is a low-cost biomagnetic tool that has been successfully applied on pharmaceutical research to evaluate performance of solid dosage forms. The aim of this work was to evaluate the Horn & Shunck method to access tablet disintegration. To evaluate the HS results was record on video a test with a objet moving in a rail with a constant velocity. The desintegration was recorded on video and ACB, which used have seven pairs of detection coils and a pair of excitation coils to mensure the magnetic ux variation. The signals were ampli ed and digitalized to create images, which were restored by Wiener lter, while the video images are converted to gray scale, both are normalized and binarized and had the optical ow estimation calculated by Horn & Schunck (HS) algorithm. All signals and images are processed and developed algorithm on Matlab. During the tests the ve tablets (500mg ferrite, 375mg excipients, compression 10 to 50 kN) were on a becker between of the ACB system and of the video system, and only touching the surface of the water. With all OF maps calculated was realized the sum of the resultants of each, to get a disintegration process resultant for each compression. Whit that was possible observed the disintegration behaves. For the compression force study the HS components of each sequence was sum, take mean and normalized for sequence's max modulo, therefore can be observed a high growing on less compression tablets. We can conclude the HS algorithm is viable to tablets disintegration data collection and whit that was possible to create a tablets disintegration analyzes protocol, which would be useful on desintegration kinetics study

Root morphology and phosphorus uptake by potato cultivars grown under deficient and sufficient phosphorus supply

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reciclagem de resíduos eletroeletrônicos: um estudo cinético da lixiviação ácida de ferro de placas de circuito impresso de microcomputadores.

O aumento no consumo mundial de novos aparelhos eletroeletrônicos aliado à redução no tempo de vida útil destes equipamentos tem como principal consequência ao meio ambiente a geração de resíduos. No Brasil, com a instituição da Política Nacional de Resíduos Sólidos, criou-se a obrigatoriedade legal da responsabilidade dos fabricantes pela logística reversa dos equipamentos eletroeletrônicos, incentivando pesquisas para o desenvolvimento dos métodos de reciclagem e tratamento dos materiais descartados. O processo de lixiviação foi avaliado como alternativa à etapa de separação magnética presente nas atuais rotas hidrometalúrgicas para recuperação de metais valiosos de placas de circuito impresso. Para avaliar a composição das placas, foi realizado ensaio de dissolução em água régia. As amostras foram moídas e submetidas a ensaios de lixiviação com ácido sulfúrico nas concentrações de 1 e 2mol/L, às temperaturas de 75ºC, 85ºC e 95ºC, durante 24 horas. Com ácido sulfúrico 2mol/L a 95ºC, o tempo necessário para se obter 100% de extração do ferro foi de 2 horas. Nestas condições, não foi detectada a presença de cobre dissolvido. A cinética da reação é controlada por reação química e obedece a equação .=1(1)3. A energia de ativação aparente do processo equivale a 90kJ/mol.

Usos de membranas de quitosana na remoção de cobre em águas residuais

In this work a chitosan (CS) ionically crosslinked were manufactured by treatment with sulfuric acid solution for application in the treatment of wastewater from oil industry. Two crosslinking process were developed: homogeneous and heterogeneous. In the homogeneous process the ratio molar of SO42-/ NH3+ (1:6 and 1:4) were the variable analyzed, denominated CS16 and CS14 respectively. In the heterogeneous process the soaking time of the membranes in sulfuric acid solution were the variable studied, being used times of 5 (CS5) and 30 (CS30) minutes. FTIR-ATR results indicated no changes in the characteristics of chitosan after homogeneous crosslinking process, while heterogeneous crosslinking showed formation of ionic bonds between protonated groups from chitosan and the crosslinking agent sulfate ions. TG/DTG and XRD analysis confirmed the formation of these interactions, as also shown the new structure on the surface region of CS5 and CS30 membranes compared to CS, CS16 e CS14. Swelling test in aqueous medium have shown that crosslinking process reduced the membrane sorption capacity. Swelling test in acid medium demonstrated that CS16 and CS14 membranes increasing the adsorption capacity up to a maximum percentage of 140% approximately, whereas the CS5 e CS30 reached a maximum of 60%. The mechanical properties indicated the stiff and ductile behavior of crosslinked membrane. Adsorption experiments of CuCl2 results that CS16 membranes reached the efficiency maximum with 73% of copper removal at pH 5.0 and 87% at pH 4.0. The experiments with CuSO4 also obtained efficiency maximum to the CS16 membrane and 80% to the removal of Cu2+ ions. Also was verified that the increase of concentration and temperature cause a decrease in the adsorption capacity for all membranes. Kinetics study indicated that pseudo-second-order obtained characterized better the membranes. Equilibrium studies demonstrated that the CS, CS16 and CS14 follow the Langmuir model, whereas CS5 and CS30 follows Freundlich model. Filtration experiments results with rejection maximum to the CS16 and CS5 membranes, reaching 92 and 98% respectively.

Usos de membranas de quitosana na remoção de cobre em águas residuais

In this work a chitosan (CS) ionically crosslinked were manufactured by treatment with sulfuric acid solution for application in the treatment of wastewater from oil industry. Two crosslinking process were developed: homogeneous and heterogeneous. In the homogeneous process the ratio molar of SO42-/ NH3+ (1:6 and 1:4) were the variable analyzed, denominated CS16 and CS14 respectively. In the heterogeneous process the soaking time of the membranes in sulfuric acid solution were the variable studied, being used times of 5 (CS5) and 30 (CS30) minutes. FTIR-ATR results indicated no changes in the characteristics of chitosan after homogeneous crosslinking process, while heterogeneous crosslinking showed formation of ionic bonds between protonated groups from chitosan and the crosslinking agent sulfate ions. TG/DTG and XRD analysis confirmed the formation of these interactions, as also shown the new structure on the surface region of CS5 and CS30 membranes compared to CS, CS16 e CS14. Swelling test in aqueous medium have shown that crosslinking process reduced the membrane sorption capacity. Swelling test in acid medium demonstrated that CS16 and CS14 membranes increasing the adsorption capacity up to a maximum percentage of 140% approximately, whereas the CS5 e CS30 reached a maximum of 60%. The mechanical properties indicated the stiff and ductile behavior of crosslinked membrane. Adsorption experiments of CuCl2 results that CS16 membranes reached the efficiency maximum with 73% of copper removal at pH 5.0 and 87% at pH 4.0. The experiments with CuSO4 also obtained efficiency maximum to the CS16 membrane and 80% to the removal of Cu2+ ions. Also was verified that the increase of concentration and temperature cause a decrease in the adsorption capacity for all membranes. Kinetics study indicated that pseudo-second-order obtained characterized better the membranes. Equilibrium studies demonstrated that the CS, CS16 and CS14 follow the Langmuir model, whereas CS5 and CS30 follows Freundlich model. Filtration experiments results with rejection maximum to the CS16 and CS5 membranes, reaching 92 and 98% respectively.

Improving photofermentative hydrogen production through metabolic engineering and DOE (Design of Experiments)

A l’heure actuelle, les biocarburants renouvelables et qui ne nuit pas à l'environnement sont à l'étude intensive en raison de l'augmentation des problèmes de santé et de la diminution des combustibles fossiles. H2 est l'un des candidats les plus prometteurs en raison de ses caractéristiques uniques, telles que la densité d'énergie élevée et la génération faible ou inexistante de polluants. Une façon attrayante pour produire la H2 est par les bactéries photosynthétiques qui peuvent capter l'énergie lumineuse pour actionner la production H2 avec leur système de nitrogénase. L'objectif principal de cette étude était d'améliorer le rendement de H2 des bactéries photosynthétiques pourpres non sulfureuses utilisant une combinaison de génie métabolique et le plan des expériences. Une hypothèse est que le rendement en H2 pourrait être améliorée par la redirection de flux de cycle du Calvin-Benson-Bassham envers du système de nitrogénase qui catalyse la réduction des protons en H2. Ainsi, un PRK, phosphoribulose kinase, mutant « knock-out » de Rhodobacter capsulatus JP91 a été créé. L’analyse de la croissance sur des différentes sources de carbone a montré que ce mutant ne peut croître qu’avec l’acétate, sans toutefois produire d' H2. Un mutant spontané, YL1, a été récupéré qui a retenu l'cbbP (codant pour PRK) mutation d'origine, mais qui avait acquis la capacité de se développer sur le glucose et produire H2. Une étude de la production H2 sous différents niveaux d'éclairage a montré que le rendement d’YL1 était de 20-40% supérieure à la souche type sauvage JP91. Cependant, il n'y avait pas d'amélioration notable du taux de production de H2. Une étude cinétique a montré que la croissance et la production d'hydrogène sont fortement liées avec des électrons à partir du glucose principalement dirigés vers la production de H2 et la formation de la biomasse. Sous des intensités lumineuses faibles à intermédiaires, la production d'acides organiques est importante, ce qui suggère une nouvelle amélioration additionnel du rendement H2 pourrait être possible grâce à l'optimisation des processus. Dans une série d'expériences associées, un autre mutant spontané, YL2, qui a un phénotype similaire à YL1, a été testé pour la croissance dans un milieu contenant de l'ammonium. Les résultats ont montré que YL2 ne peut croître que avec de l'acétate comme source de carbone, encore une fois, sans produire de H2. Une incubation prolongée dans les milieux qui ne supportent pas la croissance de YL2 a permis l'isolement de deux mutants spontanés secondaires intéressants, YL3 et YL4. L'analyse par empreint du pied Western a montré que les deux souches ont, dans une gamme de concentrations d'ammonium, l'expression constitutive de la nitrogénase. Les génomes d’YL2, YL3 et YL4 ont été séquencés afin de trouver les mutations responsables de ce phénomène. Fait intéressant, les mutations de nifA1 et nifA2 ont été trouvés dans les deux YL3 et YL4. Il est probable qu'un changement conformationnel de NifA modifie l'interaction protéine-protéine entre NifA et PII protéines (telles que GlnB ou GlnK), lui permettant d'échapper à la régulation par l'ammonium, et donc d'être capable d'activer la transcription de la nitrogénase en présence d'ammonium. On ignore comment le nitrogénase synthétisé est capable de maintenir son activité parce qu’en théorie, il devrait également être soumis à une régulation post-traductionnelle par ammonium. Une autre preuve pourrait être obtenue par l'étude du transcriptome d’YL3 et YL4. Une première étude sur la production d’ H2 par YL3 et YL4 ont montré qu'ils sont capables d’une beaucoup plus grande production d'hydrogène que JP91 en milieu d'ammonium, qui ouvre la porte pour les études futures avec ces souches en utilisant des déchets contenant de l'ammonium en tant que substrats. Enfin, le reformage biologique de l'éthanol à H2 avec la bactérie photosynthétique, Rhodopseudomonas palustris CGA009 a été examiné. La production d'éthanol avec fermentation utilisant des ressources renouvelables microbiennes a été traitée comme une technique mature. Cependant, la plupart des études du reformage de l'éthanol à H2 se sont concentrés sur le reformage chimique à la vapeur, ce qui nécessite généralement une haute charge énergetique et résultats dans les émissions de gaz toxiques. Ainsi le reformage biologique de l'éthanol à H2 avec des bactéries photosynthétiques, qui peuvent capturer la lumière pour répondre aux besoins énergétiques de cette réaction, semble d’être plus prometteuse. Une étude précédente a démontré la production d'hydrogène à partir d'éthanol, toutefois, le rendement ou la durée de cette réaction n'a pas été examiné. Une analyse RSM (méthode de surface de réponse) a été réalisée dans laquelle les concentrations de trois facteurs principaux, l'intensité lumineuse, de l'éthanol et du glutamate ont été variés. Nos résultats ont montré que près de 2 moles de H2 peuvent être obtenus à partir d'une mole d'éthanol, 33% de ce qui est théoriquement possible.