Utilização de serragem e bagaço de cana-de-açúcar para adsorção de cádmio

Abstract

ResumoOs metais provenientes de atividades antropogênicas contaminam o ambiente, insumos e matérias-primas e, conseqüentemente, a cadeia trófica, alcançando assim o homem. Em função do acúmulo desses metais, bem como de suas conseqüências danosas, estão sendo realizados estudos para avaliar os níveis alcançados por tais contaminações. O objetivo deste trabalho foi testar a capacidade da serragem e do bagaço de cana-de-açúcar, em adsorver metais pesados a partir de soluções modelo de cloreto de cádmio, nas concentrações de 25 e 50 mg.L -1 . As triplicatas das amostras tomadas para análise foram secas ao ar em ambiente arejado, sem quaisquer processamentos, sendo os experimentos conduzidos com 10 g de resíduo e 500 mL de solução de cloreto de cádmio em reatores de PVC com capacidade de 1300 mL, e a homogeneização feita manualmente durante o contato de até 16 horas 32 . Como a capacidade de adsorção do metal pela serragem não foi esgotada na primeira utilização, estudou-se a possibilidade de um novo contato reutilizando-se a solução remanescente, mantendo a proporção 1:50 32. Numa segunda etapa, foram testados tempos de 12, 8 e 4 horas. O teor de cádmio foi determinado por espectrofotometria de absorção atômica (EAA) na solução de contato, após separação da serragem por filtração. Pelos resultados obtidos, podemos dizer que estes resíduos podem ser utilizados como adsorventes de metais pesados no tratamento de efluentes. Palavras-chave: metal pesado; adsorção; cádmio; resíduo; contaminação. AbstractMetals which come from anthropogenic activities contaminate the atmosphere, inputs and raw materials and, consequently, the trophic chain, thus affecting humankind. Due to the accumulation of these metals, as well as their harmful consequences, studies are being carried out to evaluate the levels reached by such contaminations. The objective of this work was to test the capacity of the sawdust and pulp from cane, in adsorber heavy metals from model solutions of chloride of cadmium, at the concentrations of 25 and 50 mg.L -1. The triplicates of samples taken for analysis were dried in the air in an airy atmosphere, without any processes, and the experiments were done with 10 g of residue and 500 mL of solution of chloride of cadmium in PVC reactors with a capacity of 1300 mL, where the homogeinization was made manually during the contact of 16 hours 25 . As the capacity of adsorption of the metal for the residue was not drained at first, the possibility of a new contact reusing the remaining solution was studied, maintaining the proportion at 1:50 25 . In a second stage they were tested at times of 12, 8 and 4 hours. The amount of cadmium was determined by the atomic absorption spectrofotometry (AAS) in the contact solution, after separating the residue for filtration. According to the results, we can say that these residues can be used as adsorbents of heavy metals in effluent treatment. Keywords: heavy metal; adsorption; cadmium; residue; contamination. Utilização de serragem e bagaço de cana-de-açúcar para adsorção de...

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