Simultaneous Removal of Multiple Heavy Metals from Aqueous Solution Using Rice Husk-Derived Biosorbent

Abstract

In this study the presence of multiple heavy metals in wastewater poses a serious environmental and public health challenge due to their non-biodegradable nature, bioaccumulation, and toxicity even at trace concentrations. This study investigates the simultaneous removal of selected heavy metals lead (Pb²⁺), cadmium (Cd²⁺), and chromium (Cr⁶⁺) from synthetic aqueous solutions using rice huskderived biosorbents. Rice husk, an abundant agricultural byproduct, was processed through washing, drying, and thermal treatment to enhance its adsorptive properties. Characterization techniques such as FTIR, SEM, and BET surface area analysis were employed to determine surface morphology and functional groups responsible for metal ion binding. Batch adsorption experiments were conducted to examine the effect of critical parameters including initial metal concentration, pH, contact time, and biosorbent dosage. The adsorption data were analyzed using Langmuir and Freundlich isotherm models, while kinetic behavior was assessed using pseudo-first-order and pseudo-second-order models. The results demonstrated high removal efficiencies (>85%) for all three metals under optimized conditions, with evidence of selective affinity and competitive adsorption behavior. This study underscores the potential of rice husk as a low-cost, eco-friendly, and effective biosorbent for simultaneous removal of multiple heavy metals, contributing to sustainable and circular approaches in wastewater remediation.