Adsorption kinetics of Cd(II), Zn(II) and Cu(II) and their mixtures from an aqueous solution onto immobilized activated sludge

In this study, we determined the kinetics of cadmium, zinc, and copper removal by an activated sludge immobilized in 1.5% sodium alginate with 0.5% polyvinyl alcohol. The adsorption of metals from solutions of both single metals and their mixtures was found to follow the pseudo-second-order reaction. In the solutions of single metals cadmium was most effectively adsorbed (96.10 mg g(-1) d.m.); whereas in metal mixtures, it was copper (37.38 mg g(-1) d.m). It was also observed that the presence of copper in a mixture of metals impaired the sorption of cadmium and zinc.