Synthesis of powdered and beaded chitosan materials modified with ZnO for removing lead (II) ions.

Lead contamination in wastewater may affect aquatic organisms, the environment, and human consumption because it is a highly toxic metal that caused human health effects. Thus, it is recommended to remove lead before releasing it into the environment. Powdered and beaded chitosan materials modified with ZnO were synthesized and investigated by various characterized techniques. Lead removal efficiencies of chitosan materials were studied by batch experiments, adsorption isotherms, and kinetics. Chitosan powder (CP), chitosan beads (CB), chitosan beads mixed ZnO (CZB), and chitosan beads coated ZnO (ZCB) were synthesized. CP represented a semi-crystalline structure while CB was an amorphous structure. CZB and ZCB were semi-crystalline structures with ZnO peaks. CP was a scaly-sheet and coarse surface while CB, CZB, and ZCB were sphere shapes with scaly-sheet surfaces. C, O, and N were the main chemical elements in chitosan materials, and Zn was detected in CZB and ZCB. O-H, N-H, and C-O were the main functional groups of chitosan materials. All chitosan materials had high lead removal efficiencies of more than 92%, and Freundlich and pseudo-second-order kinetic models well explained their adsorption patterns and mechanisms. Therefore, both adding metal oxide and changing material form are recommended for improving material efficiency, and ZCB was a good offer for further industrial applications.