Analysis of heat treatment of chicken bones for the obtaining of phosphate biofertilizer Análise do tratamento térmico de ossos de frango para obtenção de biofertilizante fosfatado
Two different reactive concentrated magnesium hydroxide (HM) pulps, produced in a lab reactor mill, and a synthetic and non-reactive HM-pulp, for comparative analyses, have been prepared and studied. Sodium polyacrylate was selected as a dispersant for improving the HM pulp fluidity, with concentrations varying from 0.42% to 2.0% on a dry basis. The two reactive pulps differed from each other mainly by the impurity level and for both, a residual MgO amount was detected, implying that the hydration reaction could proceed. Results (with and without dispersant) confirmed the formation of particle clusters as HM concentration rose until a critical value, above which the pulp behaved as a solid. Reactive HM-pulps with high impurities may represent a limiting factor in the drying operation. Among all HM-pulps studied, the purest reactive pulp with 1% dispersant presented the best flow behavior making this reactive pulp the most suitable to be tested in a pilot spray dryer.
KINETIC AND THERMODYNAMIC ANALYSIS OF THE BIOSORPTION OF Pb(II) IN BATCH AND WITHOUT AGITATION USING ANNATTO SHELLSO estudo da remoção de metais pesados através da biossorção utilizando materiais naturais e alternativos possui grande importância em tratamento de efluentes, promovendo a redução dos impactos ambientais. Além disso, materiais sustentáveis de baixo custo e que geralmente são descartados podem ser usados como adsorventes, como a casca de urucum. Neste trabalho, realizou-se a biossorção de íons Pb (II) em batelada utilizando casca de urucum como biossorvente, nas temperaturas de 32 e 40°C. Caracterizou-se as partículas do biossorvente quanto ao seu tamanho, estudou-se a cinética e os mecanismos da biossorção, bem como seus parâmetros termodinâmicos. Foi possível verificar que a eficiência da biossorção do chumbo nessas condições, atingindo remoções superiores a 85% dessa espécie metálica em soluções aquosas diluídas. O modelo cinético que descreve o processo foi o de pseudo-segunda ordem, a energia de ativação de 77,36 kJ mol-1 e a biossorção pode ser classificada como química. Ademais, o processo mostrou-se não espontâneo e exotérmico.The study of the removal of heavy metals through biosorption using natural and alternative materials is a great importance in the treatment of effluents, improving the reduction of environmental impacts. In addition, sustainable and low-cost materials which are usually discharded can be used as sorbent, as annatto shells. In this work, the biosorption of Pb (II) ions in batch system without agitation using annatto shells as biosorbent was performed, at 32°C and 40°C. The biosorbent particles were characterized according to their size, kinetic and thermodynamic parameters, furthermore, its mechanisms were studied. It was possible to verify the biosorption efficiency under these conditions, achieving removals of more than 85% of lead in dilute aqueous solutions. The kinetic model that describes the process was the pseudo-second order, the activation energy is 77.36 kJ mol-1 and the biosorption can be classified as chemical. In addition, the process proved to be non-spontaneous and exothermic.
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