BIOSORPTIVE BEHAVIOR OF CASEIN FOR ZN2- EFFECTS OF PHYSICOCHEMICAL TREATMENTS(, HG2+ AND CR3+ )

The uptake behaviour of milk protein (casein) for some heavy metal tox ic ions [Zn2+, Hg2+ and Cr3+] was investigated by employing the 'radio tracer technique'. The effects of various physico-chemical treatments were investigated in order to explain the sequestering behaviour of th is biomass. In a single batch equilibrium experiment a decrease in ads orptive concentration (10(-2)-10(-8) mol L-1) and increase in temperat ure (293-323 K) and pH (ca 3-10) specifically increased the uptake of the metal ions. The uptake followed a first-order rate law and obeyed the Freundlich isotherm. Changes in standard enthalpy and activation e nergy involved during the biosorption were deduced for these systems. Also, desorption experiments showed that no significant desorption too k place. (C) 1998 Elsevier Science Ltd.