UPTAKE OF LEAD, CADMIUM AND ZINC BY A NOVEL BACTERIAL EXOPOLYSACCHARIDE

The biosorption of the three metallic ions, lead, cadmium and zinc, in single component and bi-component mixtures in aqueous solutions by an exopolysaccharide (EPS) is reported. The isotherms are plotted to obt ain the maximum of uptake capacities and apparent dissociation constan ts. A comparison is made between the one metal sorption system and the influence of a second metal on the uptake of the primary one. The com petitive effect on the uptake of various heavy metals on the Alteromon as macleodii subsp fijiensis has been studied using the Langmuir model for bisolute systems; The isotherms indicate a competition for the sa me binding site with zinc and cadmium. Lead is preferentially complexe d by EPS in the bi-component solutions. The hydrothermal bacterial exo polysaccharide is shown to possess an affinity for the tested metal io ns which makes its use as a biosorbent a possible alternative to the o ther common methods. (C) 1997 Elsevier Science Ltd.