The Preparation of a Lignosulfonate/Chitosan–Graphene Oxide Hydrogel Biosorbent to Effectively Remove Cr(VI) from Wastewater: Adsorption Performance and Mechanisms

Abstract

A lignosulfonate/chitosan–graphene oxide hydrogel (LCGH) composite was successfully synthesized to effectively remove Cr(VI) from wastewater. The physical–chemical properties of the prepared LCGH was characterized by SEM, FT-IR, XRD, XPS, and TGA. The results showed that LCGH had an cross-linked three-dimensional porous network structure that was conducive to Cr(VI) adsorption, resulting in a high Cr(VI) adsorption capacity (564.2 mg/g). Thermodynamic analysis showed that Cr(VI) adsorption on LCGH was spontaneous endothermic and fitted well with the pseudo-second-order kinetic and Langmuir models. The reaction mechanisms for Cr(VI) removal were hydrogen bond, electrostatic attraction, and π-π interaction. LCGH demonstrated good reproducibility and its adsorption capacity of Cr(VI) could still maintained at 85.4% after 5 cycles of regeneration. The biosorbent LCGH was a low-cost and eco-friendly material, which has a good prospect for Cr(VI) wastewater removal.