Abstract:A novel sorbent, bio-formulation(BF), was prepared and employed for the adsorption of cadmium(Cd) ion from aqueous system. The process of adsorption follows the pseudo second-order kinetic equation and the adsorption behavior is fitted with a Freundlich isotherm. The removal rate of Cd is slightly dependent on the initial pH value over a wide range of 4−11. The addition of Zn2+ and Cu2+ ions hardly affects the Cd adsorption, whereas the coexisting Pb2+ ion greatly interferes with the adsorption. The adsorption mechanism is supposed as a cation-exchange process between Cd2+ and calcium and Mg2+ present on the surface of BF, and somewhat as adsorption in a hydrolyzed form. The adsorbed Cd ions are desorbed effectively by a 0.1 mol/L HCl solution.

Key words: cadmium; bio-formulation(BF); adsorption; desorption