Chelating properties of bacterial exopolysaccharides from deep-sea hydrothermal vents

The metal-binding properties of four bacterial exopolysaccharides originating from deep-sea hydrothermal vents were investigated in batch experiments. The effect of pH on ion uptake was also investigated. Removal of toxic elements such as lead, cadmium and zinc occurred according to a chemical, equilibrated and saturable mechanism, following the typical Langmuir model. The sorption isotherms were plotted to obtain the maximum of uptake capacities and apparent dissociation constants. Maximum uptake capacities reached 316 mg g(-1), 154 mg g(-1) and 77 mg g(-1) for lead, cadmium and zinc respectively. The strong chelating properties of all polymers for the three selected metals make their use as biosorbents in wastewater treatment as a possible alternative to other physical or chemical methods. (C) 1998 Published by Elsevier Science Limited. All rights reserved.