This study has been focused on the batch culture removal of Cu2+ and Ni2+ ions from the aqueous solution using marine brown algae Sargassum angustifolium. Influences of parameters like pH, initial metal ions concentration and biosorbent dosage on nickel and copper adsorption were also examined using the Box–Behnken design matrix. For biosorption of Cu2+ the optimum pH value was determined as 5.0, optimum biosorbent concentration to 1.0 g/L and optimum initial concentration 0.15 mmol/L. For the biosorption of Ni2+, the optimal condition was the same but the optimum pH value was determined as 6.0. Desorption experiments indicated that CH3COOH and EDTA were efficient desorbents for recovery from Cu2+ and Ni2+. The Langmuir isotherm model was applied to describe the biosorption of the Cu2+ and Ni2+ into S. angustifolium. The maximum uptake of Cu2+ and Ni2+ ions by the S. angustifolium biomass under the optimal conditions was approximately 0.94 and 0.78 mmol/g dry alga, respectively. Response surface models showed that the data were adequately fitted to a second-order polynomial model. Analysis of variance showed a high coefficient of determination value (R2=0.993 for Cu2+ and 0.991 for Ni2+) and a satisfactory second-order regression model was derived. In addition, results reported in this research demonstrated the feasibility of employing S. angustifolium as biosorbent for Ni2+ and Cu2+ removal.
