Adsorptive Performance of Quinine-Functionalized Magnetic Graphene Oxide in the Treatment of Industrial Wastewater

Abstract

The increasing discharge of untreated industrial effluents poses severe environmental and public health risks due to the presence of toxic heavy metals. In this study, a novel quinine-functionalized magnetic graphene oxide (MGO@SiO2-Q) nanocomposite was synthesized and evaluated for the efficient removal of heavy metal ions from industrial wastewater. The adsorbent demonstrated outstanding removal efficiencies, achieving complete elimination (100 and 95%) of Pb(II) and Ni(II) ions and significant removal of Cr(III), Cu(II), Zn(II), and Mn(II) under optimized conditions. Adsorption performance was strongly dependent on adsorbent dosage and initial metal ion concentration. Isotherm analyses revealed that the adsorption of Pb(II) and Ni(II) fitted well to the Langmuir model, indicating monolayer adsorption with maximum capacities of 161 mg/g and 156 mg/g, respectively. The quinine functional groups provided multiple active sites, promoting ion exchange, electrostatic interactions, and surface complexation mechanisms. The magnetically responsive nature of the adsorbent allowed easy recovery and reuse, offering a sustainable and cost-effective solution for industrial wastewater treatment. These findings highlight the potential application of MGO@SiO2-Q as a green, efficient, and recyclable adsorbent for environmental remediation.