Optimization of Lead and Nickel Biosorption by <i>Cystoseira trinodis</i> (Brown Algae) Using Response Surface Methodology

Response surface methodology was used to optimize conditions for lead (Pb 2+ ) and nickel (Ni 2+ ) biosorption from aqueous solutions, using Cystoseira trinodis (brown algae). The experiments are carried out in a batch system with 0.2 g of biomass per batch. The variables as pH, initial metal concentration, and contact time were optimized as the critical components. A central composite rotatable design was used for experimental design and analysis of results. The experimental data for the uptake of the metal ions were best described by the quadratic models proposed. Using these models gave a coefficient of determination ( R 2 ) value of 0.9998 for Pb 2+ and 0.9741 for Ni 2+ . The factors which showed the greatest influence on the biosorption of both ions were the initial ion concentration and contact time. Under optimum conditions, the biosorption of Pb 2+ was found to be 49.08 mg/g, and 14.58 mg/g for Ni 2+ . These conditions for Pb 2+ were a pH of 5.2, initial ion concentration of 200 mg/L and a contact time of 60 min. For Ni 2+ , they were a pH of 5.8, initial ion concentration of 190 mg/L and a contact time of 53 min.