Biosorption of copper and chromium by sargtassum sp: Determination of biosorption properties and investigation of metal-sorbent interactions

Abstract

Copper and chromium biosorption properties by raw and chemically modified Sargassum sp. were investigated in this study. By modification with 0.2% formaldehyde, the organic leaching from the Sargassum sp. was reduced by 54-80% and the adsorption capacities for both contaminants were improved by 38-87%. The sorption kinetics was well remained. In both five-cycle batch and continuous column sorption processes, 0.2 M hydrochloric acid was able to elute more than 90% copper ions from the sorbents in less than 20 min. At pH > 6, 99% chromium(VI) in the Cu(II)-Cr(VI) systems was removed via copper-chromium co-precipitation. The instrumental analysis showed that copper was removed through ion exchange and coordination reactions, while redox-reduction controlled chromium(VI) biosorption process. The binding structures were copper acetate and chromium(III) acetate respectively. The surface diffusion model well described the copper biosorption kinetics. A new model based on ion exchange and coordination reactions was formulated and successfully simulated the single and multiple metal biosorption process under the influence of pH and competitive ions.