Tailoring of a chitosan-based adsorbent with target-specific sites for efficient adsorption-reduction of chromium ion pollutant

Chromium (Cr) ion is a serious pollutant in industrial wastewater, and the removal and simultaneous detoxification of Cr(VI) remains a persistent challenge. Here, we present a novel chitosan-based adsorbent, GA/CS-PEI-PVA (GCPP), designed with crosslinked networks and target-specific sites by incorporating polyethyleneimine (PEI), polyvinyl alcohol (PVA), and 3,4,5-trihydroxybenzoic acid (GA) into chitosan. The harvested GCPP demonstrated enhanced thermal stability, mechanical strength, and specific surface area. Remarkably, GCPP achieved a Cr ion adsorption capacity of up to 290.77 mg·g⁻¹ and a reduction ratio of Cr(VI) to Cr(III) of 83.20 %. Mechanism studies revealed that the adsorption of Cr ion on GCPP involved complexation and electrostatic attraction processes, while the grafted phenolic hydroxyl groups significantly promoted the detoxification of Cr(Ⅵ) to Cr(Ⅲ). This study represents a significant advance in the development of efficient adsorbents for the practical treatment of Cr ion-containing pollutants.