RESEARCH ARTICLE Competitive biosorption of lead, cadmium, copper, and arsenic ions using algae

Abstract The present study aims to evaluate the competi-tive biosorption of lead, cadmium, copper, and arsenic ions by using native algae. A series of experiments were carried out in a batch reactor to obtain equilibrium data for adsorp-tion of single, binary, ternary, and quaternary metal solu-tions. The biosorption of these metals is based on ion exchange mechanism accompanied by the release of light metals such as calcium, magnesium, and sodium. Experimental parameters such as pH, initial metal concen-trations, and temperature were studied. The optimum pH found for removal were 5 for Cd2+ and As3+ and 3 and 4 for Pb2+ and Cu2+, respectively. Fourier transformation infrared spectroscopy analysis was used to find the effects of func-tional groups of algae in biosorption process. The results showed that Pb2+ made a greater change in the functional groups of algal biomass due to high affinity to this metal. An ion exchange model was found suitable for describing the biosorption process. The affinity constants sequence calcu-lated for single system was KPb> KCu> KCd> KAs; these values reduced in binary, ternary, and quaternary systems. In addition, the experimental data showed that the biosorption of the four metals fitted well the pseudo-second-order kinetics model