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Invertase from NOVO Nordisk has been immobilized in controlled pore silica particles (diameter: 0.351 mm and mean pore size: 37.5 nm) by covalent binding with the silane-glutaraldehyde method. The activity of the free and immobilized enzyme (IE) was determined with 5% (w/v) sucrose, at 35 to 65ºC and pH from 3 to 7. Maximum activities were found in the pH range from 5 to 6 for free invertase, and pH 4.5 for the IE. Activity yield for the IE was 24%. The Energy of Activation (Ea) was found to be a function of pH, giving for free invertase, Ea = 7.0 and 6.86 kcal/mol at pH 5.0 and 5.5, respectively, whereas for the immobilized enzyme, Ea = 6.55 and 5.93 kcal/mol at pH 4.5 and 5.0, respectively

Lead is a heavy metal considered highly toxic, responsible for causing several health problems as well as being extremely harmful to fauna and flora. Given this fact, several techniques have been studied for the removal of this metal from contaminated water, in which stands out adsorption. In this sense, the objective of this study was to evaluate the potential of lead(II) biosorption from contaminated water by seed husks, seeds and pods of Moringa oleifera Lam (moringa). Biomass was characterized by energy-dispersive X-ray spectroscopy, Scanning Electron Microscopy and Fourier transform infrared spectroscopy analyses. From the studied parameters, the optimal conditions obtained for the three analyzed biosorbents are: 30 min to equilibrium, pH 6 and 25°C temperature. The pseudo-second-order kinetic model was the best fitted to the experimental data for the three evaluated biosorbents. Regarding the adsorption isotherms, the model that best fitted to the experimental data for seed and seed husk was that proposed by Freundlich, and for the pod the Langmuir model. The analysis of the obtained thermodynamic data showed that the adsorption process is favorable and of exothermic nature. Through the results it was concluded that the evaluated biosorbents are efficient in lead(II) biosorption.

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The thermal stability and the energy of deactivation of free invertase and the immobilized enzyme (IE) was measured at temperatures in the range of 35 to 65°C for the hydrolysis of a 5% w/v sucrose solution. The free enzyme at pH 5.0 is stable up to 50°C for a period of 4 h. Invertase immobilized in controlled pore silica by the silane-glutaraldehyde covalent method is stable up to 55ºC, in pH 4.5 for the same period. For higher temperatures the enzyme deactivation follows the exponential decay model and half-lives are 0.53, 1.80, and 13.9 h for free invertase, at 65, 60, and 55ºC, respectively. For the IE half-lives are 0.48, 1.83, and 20.9 h, at 65, 60, and 55ºC, respectively. The IE is more stable than the free invertase; the energy of deactivation being 83.1 kcal/mol for the IE and 72.0 kcal/mol for the free enzyme

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O sulfato de alumínio e o policloreto de alumínio são coagulantes químicos eficientes para formação de flocos em unidades de tratamento de água. No entanto, estes coagulantes podem contribuir para o desenvolvimento da doença de Alzheimer pelo alumínio residual na água pós-tratamento. Em razão disso, esta pesquisa teve como objetivo verificar a aplicação de extrato salino (CaCl2) de sementes de Moringa oleifera no tratamento de águas com baixa turbidez, usando flotação por ar dissolvido (FAD). A eficiência do processo foi determinada mediante os parâmetros cor, turbidez, pH e condutividade, os quais foram discriminados por Análise de Componentes Principais. Duas condições de turbidez (10 e 20 uT) foram utilizadas neste estudo, enquanto os ensaios de coagulação, floculação e FAD foram realizados com extratos salinos da semente nas dosagens de 10, 20, 30, 40 e 50 mg L-1. Os resultados indicaram que houve remoção de turbidez (64,2 e 78,2%) e cor (77,6 e 72,4%) em águas com turbidez de 10 e 20 uT, respectivamente. A condutividade aumentou em função do maior acréscimo de coagulante, enquanto o pH não foi alterado de forma significativa. Concluiu-se, desta forma, que o uso do coagulante Moringa oleifera favoreceu a remoção dos parâmetros cor e turbidez, melhorando a qualidade da água. Palavras-chave: Qualidade da água. Coagulante natural. Flotação por ar dissolvido. Análise Quimiométrica.