Combining mussel and seaweed hydrogel-inspired strategies to design novel ion-imprinted sorbents for ultra-efficient lead removal from water

Abstract

Lead(II) is one of the most toxic heavy metals and is a serious threat to the environment and human health. By combining mussel and seaweed hydrogel-inspired strategies, a novel ion-imprinted polymer (IIP) was prepared by a bulk imprinting method using polydopamine (PDA)-polyethyleneimine (PEI)-modified CaCO₃ composites (solid porogens with amine groups) and sodium alginate (SA) as the functional platform for ultra-efficient and selective capture of Pb(II) from wastewater. The hollow cavity structures with high-density reactive sites were immobilized favorably into the interior of the alginate hydrogel. The aim of modification using polydopamine (PDA) and polyethyleneimine (PEI) was to enhance the removal performance for Pb(II) ions under aqueous conditions. Pb(II)-IIP showed a higher capacity and selectivity than the non-imprinted polymer (NIP). The monolayer adsorption capacities of Pb(II)-IIP and NIP were 357.4 and 296.8 mg g⁻¹, respectively. The relative selectivity coefficients of Pb(II)/Cd(II), Pb(II)/Ni(II) and Pb(II)/Cu(II) were 27.32, 22.53 and 5.462, respectively. Kinetics studies showed that the experimental data fitted well with the pseudo-second-order model. Moreover, Pb(II)-IIP exhibited an excellent regeneration ability and adsorption capacity with no obvious decrease after five cycles. These results indicated that the new Pb(II)-IIP could have wide application prospects in Pb(II) removal.