Ion-imprinted sponge produced by ice template-assisted freeze drying of salecan and graphene oxide nanosheets for highly selective adsorption of mercury (II) ion

Abstract As a kind of potential heavy metal absorbent, polysaccharide-based materials are limited by the complicated preparation method and bad selectivity toward targeted ion. Here, a fantastic sponge was produced by combining salecan and graphene oxide (GO) nanosheets via ice template-assisted freeze drying and ion-imprinting technologies. The intense intermolecular interactions between salecan and GO gave the sponge high stability. The swelling, morphology, and mechanical stiffness of the material showed highly dependent on the salecan content. Additionally, the influence of salecan content, pH, initial ion concentration, and contact time on Hg2+ adsorption was extensively investigated. Adsorption kinetics and equilibrium isotherms perfectly fitted in the pseudo-second-order and Freundlich models, reflecting the multilayer chemical-adsorption mediated mechanism. Most strikingly, the ion-imprinted sponge exhibited strong selectivity toward Hg2+ and outstanding stability with recyclability over usage of five times. These investigations provide the guidance for the construction of promising polysaccharide-based adsorbents for the remediation of Hg2+-polluted water.