Hexavalent chromium removal using reduced graphene oxide-zinc oxide composite fabricated via simple pyrolysis method

Abstract

The contamination of water by heavy metals from various industrial effluents is a significant factor contributing to the scarcity of clean water worldwide. To address this issue, there is a need to develop low-cost adsorbents to remove heavy metals from contaminated water reduced graphene oxide (rGO) based composites are efficient adsorbers of heavy metals. In this study, a green and rapid single-step heating process was utilized to prepare both rGO and rGO/ZnO composite materials, avoiding the use of any toxic reagents. The rGO/ZnO composite synthesized from sucrose and zinc acetate demonstrates a remarkable ability to adsorb hexavalent chromium (Cr(VI)). The Cr adsorption studies were carried out by varying adsorbent, contact time, initial pH, and concentration. The adsorption efficiency of the composite is five times higher than that of pure rGO. The adsorption mechanism of Cr(VI) onto the adsorbent is electrostatic interaction, complexation, pore filling, and reduction, identified through Zeta potential measurement, BET, EDX, and XPS analysis. These studies suggest that rGO/ZnO composite has great potency as a cost-effective and efficient adsorbent for removing Cr(VI) contaminants from industrial effluents.