Biosorption of Lead (II) and Cadmium (II) from Aqueous Solutions by Protonated Sargassum Sp. Biomass

Biosorption of lead (II) and cadmium (II) from aqueous solutions in batch system by protonated brown algae Sargassum sp. biomass was studied. The data obtained from experiments of single-component biosorption isotherms were analyzed using the Freundlich, Langmuir, Freundlich-Langmuir and Redlich-Peterson isotherm models. The Redlich- Peterson equation was found in the best fitness with the experimental data. The other models too described the isotherms of Pb2+ and Cd2+ biosorption with relatively high correlation coefficient (R2>0.93). According to the Langmuir model, the maximum uptake capacities (qm) of Sargassum sp. for Pb2+ and Cd2+ were obtained 1.70 and 1.02 mmol g-1, respectively. The optimum initial pH values for biosorption of Pb2+ and Cd2+ were determined as 4.5 and 5.0, respectively. The effect of Na+, K+, Mg2+ and Ca2+ (light metal ions) on equilibrium capacities of Pb2+ and Cd2+ biosorption was studied in the binary system at initial heavy metal ion concentration of 1 mmol L-1 and various initial concentrations of light metal ion. The effect of Na+ and K+ on the biosorption of Pb2+ was not significant, but Mg2+ and Ca2+ decreased the equilibrium capacity of Pb2+ biosorption. The presence of Na+, K+, Mg2+ and Ca2+ in solution affected the biosorption of Cd2+ considerably, so that equilibrium uptake of Cd2+ was reduced at initial concentration 6 mmol L-1 of Na+, K+, Mg2+ and Ca2+ by 10, 17, 5 and 56%, respectively.