Site-imprinted hollow composites with integrated functions for ultra-efficient capture of hexavalent chromium from water

The design of high-efficiency adsorptive composites for selective removal of Cr(VI) ions with high capacity from aqueous solution remains great challenging owing to the complicated numerous co-existing ions. Herein, a novel type of Cr(VI) site-imprinted hollow composites (Cr(VI)-IIHS) with integrated sorption affinity, fast adsorption kinetics, capturing performance and high adsorption capacity was designed with aluminum-gelled carboxymethyl cellulose microspheres as starting substrate, Cr(VI) as the templated sites and polymeric PEI as modifying agent via a controllable glutaraldehyde cross-linking process. The adsorption of Cr(VI) over-designed Cr(VI)-IIHS could reach equilibrium within a relatively short time and the maximum adsorption capacity was 679.13 mg/g, which is the record-high adsorption results for Cr(VI) from water. Most importantly, the Cr(VI) adsorption over the Cr(VI)-IIHS remained a high level of recycling performance, for which beyond 530.91 mg/g can maintain even with six cycles of regeneration. The adsorption kinetics and equilibrium isotherms are in full agreement with the pseudo-second-order kinetic and Langmuir isotherm model, reflecting the monolayer chemisorption mechanism. By virtue of integrated features and controllable preparative process, this study might shed light on guidance for the construction of fascinating hollow adsorptive composites for remediation of emerging pollutants contaminated water-body.