Gilberto da Cunha Gonçalves

Adsorption of reactive blue BF-5G dye by soybean hulls: kinetics, equilibrium and influencing factors

The textile industry is known for the high use of chemicals, such as dyes, and large volumes of effluent that contaminate waters, a fact that has encouraged research and improved treatment techniques. In this study, we used unprocessed soybean hulls for the removal of reactive blue BF-5G dye. The point of zero charge of soybean hulls was 6.76. Regarding the speed of agitation in the adsorption process, the resistance to mass transfer that occurs in the boundary layer was eliminated at 100 rpm. Kinetics showed an experimental amount of dye adsorbed at equilibrium of 57.473 mg g(-1) obtained under the following conditions: dye initial concentration = 400 mg L(-1); diameter of particle = 0.725 mm; dosage = 6 g L(-1); pH 2; 100 rpm; temperature = 30 °C; and duration of 24 hours. The pseudo-second order best showed the dye removal kinetics. The adsorption isotherms performed at different temperatures (20, 30, 40 and 50 °C) showed little variation in the concentration range assessed, being properly adjusted by the Langmuir isotherm model. The maximum capacity of dye adsorption was 72.427 mg g(-1) at 30 °C. Since soybean hull is a low-cost industrial byproduct, it proved to be a potential adsorbent for the removal of the textile dye assessed.

Biosorption of chromium(III) in fixed bed column

The chromium (III) uptake on pre-treated seaweed Sargassum filipendula biomass was investigated in fixed bed. In the experiments 8 g of the biosorbent of 2.6 mm diameter medium were deposited in the column. The operation conditions were: feed solution pH of 3, temperature of 30oC, flow rate of 6 mL.min-1 and feed concentrations of chromium of 0.95, 1.45, 1.99, 2.82, 4.79 and 5.78 meq.L-1. The experimental equilibrium data in the column and batch systems have been analyzed using the irreversible isotherm (qmax = 1.93 meq.g-1) and the Langmuir isotherm, respectively, for simulate the sorption of chromium ion. The rupture curves obtained experimentally were modeled mathematically using a model that considers the mass transfer in the solid phase as the controlling step. The mass transfer in the solid (K) was influenced by the initial chromium concentration in the studied range. Key words: biosorption, chromium, bed fixed.

TRATAMENTO DE EFLUENTE DE FECULARIA POR COAGULAÇÃO/ FLOCULAÇÃO

O processo de industrializacao da mandioca gera um efluente vulgarmente chamado de manipueira, que apresenta alta carga orgânica e cianeto livre (HCN) altamente toxico para biota e em altas concentracoes para o ser humano. Este trabalho estudou o tempo de sedimentacao de um efluente da industria de producao de fecula de mandioca pelo processo de coagulacao/floculacao e comparou a eficiencia de remocao de cor e turbidez para dois coagulantes. As amostras de efluentes foram coletadas em uma fecularia da regiao oeste do Parana e caracterizado conforme metodologias (APHA, 1998). Foram variadas as concentracoes dos coagulantes de 15 ate 75 mg L dos coagulantes Acquapol WW e Sulfato de Aluminio, analisando cor, turbidez e pH. O experimento de coagulacao/floculacao utilizou equipamento Jart-test analogico, fixando o Tempo de Mistura Rapida, Tempo de Mistura Lenta). Obteve-se um tempo minimo de sedimentacao igual a 10 min e verificou-se que o coagulante natural (87,71% de turbidez e 50,71% de cor) assim apresentando uma eficiencia de remocao de cor e turbidez muito superior ao sulfato de aluminio (38,7% de turbidez e 26,39% de cor) na menor concentracao. )

Effect of volumetric flow rate on the breakthrough curves for the biosorption of Cr (III) and Ni (II)

Em um leito fixo, o comportamento de adsorcao baseia-se nas zonas de transferencia de massa (ZTM). Para uma vazao de operacao na qual a coluna forneca curvas de ruptura proximas a idealidade, tem-se uma menor ZTM e uma minimizacao das resistencias difusionais. Assim, o objetivo deste trabalho foi investigar o efeito da vazao nas curvas de ruptura para o processo de biossorcao monocomponente do ion cromo e niquel pela biomassa de Sargassum filipendula pre-tratada. A concentracao de alimentacao dos ions foi mantida constante em torno de 2 meq/L, enquanto a vazao foi variada em 2, 4, 6 e 8 mL/min. Os resultados obtidos indicaram a vazao volumetrica de 2 mL/min como a melhor condicao de operacao para ambos os sistemas, apresentando a maior capacidade util do leito empacotado (tu/tt) e retencao dos ions metalicos (Qtu). Palavras-chave: leito fixo, biossorcao, vazao volumetrica.