The biosorption process of Zn2+, Cu2+ and Ni2+ by Sargassum ilicifolium was studied in single and ternary systems. Experimental parameters such as biosorbent dose, pH and time were analyzed using response surface methodology (RSM). The overall biosorption data were best described by the pseudo second-order kinetic model. The biosorption process was slightly slower in the ternary system comparing with single system which was related to competition phenomena between metal cations in solution. In single and ternary systems, the Dubinin-Redushkevich (D-R) isotherm showed a better fit with the following sorption order: Zn2+ > Ni2+ > Cu2+. FT-IR analysis revealed that carboxylic function group would be the active binding site. In addition, the effectiveness of the biomass was investigated in several sorptionsdesorption cycles using HC
