ABSTRACT
Chitosan, as shown in Figure 1, is a well-known hetero biopolymer (natural polysaccharide) made of glucosamine and a fraction of acetylglucosamine residues (Krishnapriya and Kandaswamy, 2010). It is a biodegradable, biocompatible, and nontoxic natural polymer with a metal uptake capacity, (Jung et al., 1999; Rabea et al., 2003; Sashiwa et al., 2003; Tsigos et al., 2000; Varma et al., 2004; Xing et al., 2005) that can be obtained from the alkaline deacetylation process of the second most abundant biopolymer, chitin as given in Figure 2, which is found widely in nature and can be extracted from fungi, lobster, shells of shrimp and crab, and in the cuticles of insects. (Brugnerotto et al., 2001a, 2001b; Heux et al., 2000; Kittur et al., 1991; Volesky, 2001). The main characteristics of chitosan are hydrophilicity, harmlessness for living things and biodegradability, easy chemical derivatization, and capability to adsorb a number of metal ions. Therefore, chitosan seems to be a very interesting starting material for chelating resins (Katarina et al., 2006). The degree of polymerization and deacetylation and the distribution of acetyl groups along the polymer chain are of crucial importance for chitosan metal interacting characteristics. Making chemical derivatives is a way to alter the metal interacting characteristics of chitosan (Onsoyen and Skaugrud, 1990).
