New magnetic chitosan/alginate/Fe3O4@SiO2 hydrogel composites applied for removal of Pb(II) ions from aqueous systems

Chitosan/alginate (CHT/ALG) and magnetic CHT/ALG/Fe3O4@SiO2 composites were successfully prepared and used as adsorbent materials to remove Pb(II) from aqueous systems. New hydrogel beads were yielded through an unpublished methodology, examining the ionic strength of the chitosan (CHT) solutions. Polyvalent cations and toxic cross-linking agents such as glutaraldehyde and epichlorohydrin, frequently used to prepare CHT/ALG-based materials were not used in this study. The samples were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, thermal analysis (TAG/DSC), and zeta potential measurements. The addition of Fe3O4@SiO2 (8 ± 3 nm) significantly modified the surface morphology of the composites. The CHT/ALG/Fe3O4@SiO2(8) hydrogel comprising the highest Fe3O4@SiO2 content (8.0 wt%), displayed magnetic feature and zeta potential of −76.8 mV at pH 6.0. Kinetic and equilibrium adsorption studies reveal that Elovich and Redlich-Peterson mathematical models provide the best fits for the experimental data, respectively. The magnetic composite CHT/ALG/Fe3O4@SiO2(8) had maximum adsorption capacity (qm) of 234.77 mg g−1 and adsorption/desorption cycles designed its reuse performance. The CHT/ALG/Fe3O4@SiO2(8) hydrogel was applied to treat battery effluent, achieving 99.04% Pb(II) removal, and diminishing the turbidity from 73 to 3.0 NTU. Wastewater and battery effluents contaminated with Pb(II) may be treated using an eco-friendly magnetic hybrid material based on CHT/ALG/Fe3O4@SiO2 as the adsorbent.