Biosorption: Mechanistic Aspects

Abstract

The complex structure of plant materials and microorganisms implies that there are many ways for the metal to be taken by the biosorbent. Numerous chemical groups have been suggested to contribute to biosorption metal binding by either whole organisms or molecules. These groups comprise hydroxyl, carbonyl, carboxyl, sulfhydryl, thioether, sulfonate, amine, amino, imidazole, phosphonate, and phosphodiester. The importance of any given group for biosorption of certain metals by plant biomass depends on factors such as number of sites in the biosorbent material, the accessibility of the sites, the chemical state of the sites (availability), and affinity between site and metal (Volesky et al. 1999). Adsorption and desorption studies invariably yield important information on the mechanism of metal biosorption. This knowledge is essential for understanding of the biosorption process and it serves as a basis for quantitative stoichiometric considerations, which constitute the foundation for mathematical modeling of the process (Yang and Volesky 2000).