Abstract

Chitosan (poly [β-(1→ 4)-2-amino-2-deoxy-D-glucopyranose] β-PADG) is a natural polymer with abundant primary amino groups in its molecular structure. Due to its excellent properties such as biocompatibility, biodegradability, nontoxicity, and adsorption properties, it is a potential polysaccharide resource. The present investigation describes the preparation and characterization of novel biodegradable nanocomposite based on complexation of β-PADG with bivalent lead ion. The prepared nano-systems were stable in aqueous media at low pH. The particle size and the size of the complexes were identified by x-ray diffraction (XRD) and UV-vis spectra measurements. It was found that the size of the complexes depended on the concentrations of β-PADG and lead ions. UV-vis spectra of the nanocomposites revealed the presence of metal nanoparticles. At low concentrations, nanosized particles were formed, however, at high concentrations, formation of large aggregates with a broad size distribution was promoted. The results from the XRD measurements showed that the high concentrations of chitosan and Pb²⁺ ions favored the growth of large complexes. The β-PADG nanocomposite composed of a biodegradable biomaterial with high flocculating and heavy metal binding activity may be useful for various water treatment applications.

Key words: Chitosan, lead ions, nanoparticles, complexation.