Abstract

ADSORPTION OF TOXIC METAL IONS ONTO CHITOSAN AS BIOSORBENT

S.G.Palaskar*

Abstract

Chitosan, a biopolymer produced from crustacean shells, has applications in various areas, particularly in drinking water and wastewater treatment due to its ability to remove metallic ions from solutions. The adsorption capacity of chitosan depends on a number of parameters deacetylation degree, molecular weight, particle size and crystallinity. The purpose of this work was to study the adsorption of Copper and cadmium on chitosan produced from shrimp shells at a laboratory level. The experimental work involved the determination of the adsorption isotherms for each metal ion in a batch system. The resulting isotherms were fitted using the Langmuir model and the parameters of the equation were determined. Kinetic studies of adsorption for different metallic ions at different concentrations and with different particle sizes were performed in batch and column systems. The results showed that the adsorption capacity depends strongly on pH and on the species of metallic ions in the solution. The optimum pH value for the metallic cation adsorption was between 4 and 6, whereas for arsenic adsorption it was about 3. When the pH is not controlled, the adsorption capacity is independent of the initial pH with the solution reaching a final pH of about 7. It was also found that the Langmuir equation described very well the experimental adsorption data for each metallic ion. The adsorption capacity for the metals on chitosan is more in Copper than Cadmium.

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