Development of Biopolymer Adsorbents for Heavy Metal Ion Separations, 1996 Minimum Effluent Mills Symposium Proceedings

G.L. Rorrer & T.-Y. Hsien

Oregon State University

Biopolymers are a promising new class of adsorbent materials for separation of heavy metal ions from dilute aqueous waste streams. Of particular interest is the chitosan, a glucosamine biopolymer derived from the shells of marine organisms. Chitosan is an inexpensive, plentiful, and environmentally benign adsorbent that exhibits a high selectivity toward heavy metal ions over alkali metal ions, even at parts-per-million (ppm) level concentrations. Highly porous chitosan biopolymer beads have been synthesized which have internal surface areas exceeding 200 m 2 per gram of adsorbent and exhibit a high selectivity toward removal of toxic heavy metal ions over sodium metal ions. Adsorption capacities for cadmium ions are nearly 200 mg metal per gram of adsorbent. The material properties have also been enhanced through chemical modifications so that the adsorbent can be used in aggressive chemical environments. The potential application of transition-metal selective biopolymer adsorbents to the control of heavy metal ion accumulation in TCF bleaching sequence wash waters is proposed.