Biosorption Mechanism for Anionic Metal Species with Waste Crab Shells

H. Niu and B. Volesky*

Department of Chemical Engineering, McGill University 3610 University Street, MONTREAL, Canada H3A 2B2

Received 31 May 2002; accepted 15 January 2003


Biosorption of anionic metal species such as gold-cyanide, chromate and anionic vanadate species by acid-washed Ucides shells (AWUS) mainly involved anions binding on the positively charged amide groups of the AWUS. The binding force may relate to electrostatic attraction. No significant reduction of the selected metals was observed in the biosorption systems with AWUS. All selected metals were observed bound on AWUS at their respective original valent states, i.e. Au(I), Cr(VI) and V(V). Anionic metal species biosorption takes place through a combination of ion-exchange and adsorption. In the case of vanadate, the binding mechanism might involve other mechanism(s) in addition to the above ones.

Keywords: Biosorption; anionic metal complexes; crab shells; chitin-containing materials; chemical speciation

* Corresponding author
   E-mail : boya.volesky@mcgill.ca