Mercury removal from wastewater using agroindustrial waste adsorbents

Abstract: In this study, adsorbent materials were prepared from sugarcane bagasse and modified with thermal treatment and chemical activation through activating agents (ZnCl₂ and H₃PO₄). The modified adsorbents were then used to remove mercury (Hg(II)) from aqueous solutions. Batch adsorption experiments were performed to explore the influence of the kinetics, isotherm, and pH, on Hg(II) adsorption. The results demonstrated their high potential for Hg(II) adsorption (more than 90%) owing to the various functional groups generated via the thermochemical treatment. The adsorption process was best described by the pseudo-second-order kinetics model, the adsorption phenomenon is contemplated as a mechanism mixture due to the complex surface of the studied adsorbents, and the maximum adsorption capabilities in this study exceeded 11.47 mg g⁻¹. Hg(II) removal is related to the existence of functional groups, such as –COO⁻, –O⁻, C=C, and C=O, on the material surface that selectively bind the Hg(II) through complexation, electrostatic interaction, and complexation with electrons π. Based on these results, the adsorbent materials are determined to be effective for eliminating Hg(II) and a valuable alternative for treating water contaminated with mercury. Graphic abstract: [Figure not available: see fulltext.]