Green synthesis of iron oxide nanobiocomposite for the adsorptive removal of heavy metals from the drinking water

The current study aimed to synthesize and characterize the Duranta erecta leaves extract-based iron oxide nanoparticles (D-Fe3O4-NPs) and chitosan biopolymer-based nanocomposites (D-Fe3O4-NC). The synthesized D-Fe3O4-NC was applied for the adsorptive removal of cadmium (Cd), chromium (Cr), and lead (Pb) from water. The nanostructure, porous, rough, crystalline structure, and different functional groups of chitosan and D-Fe3O4-NPs in D-Fe3O4-NC showed that the D-Fe3O4-NC is feasible for suitable adsorbents for quantitative removal of Cd, Cr, and Pb. Based on the batch experiments, the influences of pH, adsorption time, contents of Cd, Cr, and Pb in solution, and temperature were successfully optimized. The adsorption capacities of D-Fe3O4-NC for Cd, Cr, and Pb were observed at 74.4, 76.0, and 75.2 mg g−1, respectively. The adsorption isotherms fitted the Freundlich Model equation well, and the adsorption kinetics followed pseudo-second-order kinetics for the adsorption of these toxic metals. D-Fe3O4-NC showed an excellent recyclable efficiency up to multiple analyses (n = 20). The D-Fe3O4-NC was an excellent adsorbent for removing toxic metals from municipal and hand pump water samples (% removal >93%). Therefore, the proposed D-Fe3O4-NC is the most efficient and selective adsorbent for removing Cd, Cr, and Pb from drinking water up to recommended permissible limit. © 2023 Elsevier B.V.