Hexavalent chromium removal using chitin microspheres modified by an ionic liquid cation tricaprylmethylammonium chloride (Aliquat 336)

Abstract

A novel sorbent was successfully developed by immobilizing the ionic liquid tricaprylylmethylammonium chloride (Aliquat 336) into chitin, a natural and renewable polysaccharide. The sorbent was comprehensively characterized using SEM, BET, TGA, FTIR and DRX techniques, and its performance was evaluated for the removal of Cr(VI) from aqueous solutions. The effects of key physicochemical parameters—including pH, stirring time, initial Cr(VI) concentration, and sorbent dosage—were systematically investigated. The sorbent demonstrated high selectivity performance and efficiency for Cr(VI) removal, highlighting a maximum adsorption capacity of 35 mg/g, which is 20 times greater than that of native chitin, at an optimum pH of 2. Interference studies with coexisting ions confirmed the robustness of the sorbent to remove Cr(VI) under competitive conditions. Effective desorption was achieved with a 0.1 M NaOH solution, allowing for 80 % metal recovery within 1 hour of contact. Additionally, the sorbent exhibited remarkable stability over five cycles, maintaining its high adsorption capacity without significant loss in performance.

This study underscores the potential of the new sorbent as a sustainable and efficient material for Cr(VI) remediation, combining high adsorption capacity, reusability, and eco-friendly design.