Sugarcane Bagasse Bio chars for The Removal of Hexavalent Chromium from Aqueous Solution

Abstract

Hexavalent chromium [Cr(VI)] contamination in water sources presents significant environmental and health hazards, adversely affecting aquatic ecosystems, soil integrity, and the food chain. Human exposure to Cr(VI) can lead to severe health complications, including fatal outcomes. Consequently, developing efficient water treatment methods is crucial to ensuring safe and equitable access to clean drinking water. Among various remediation strategies, adsorption using biochar has gained prominence as a cost-effective, simple, High removal efficiency, and minimal risk of secondary pollution. In this study, sugarcane bagasse (SB) biochar from sugarcane bagasse, an abundant and renewable biomass resource, was synthesized via an economical process involving NaOH and H₃PO₄ treatment, followed by carbonization, and its adsorptive removal of Cr(VI) from aqueous solution was examined. Proximate analyses were conducted on raw and acid-heat-treated SB biochar. Pretrial screening identified H₃PO₄-treated SB biochar as the most effective adsorbent, warranting further characterization through XRD, FTIR, and SEM. Batch adsorption experiments were performed to assess the impact of key operational parameters, including temperature, contact time, pH, initial Cr(VI) concentration, and adsorbent dosage. The optimal conditions for Cr(VI) removal were a contact time 7 h, pH 3.0, initial Cr(VI) concentration of 50 mg/L, adsorbent dosage of 2 g/L, and a carbonization temperature of 400°C. Equilibrium adsorption data aligned well with the Freundlich isotherm model (R² = 0.999), and the maximum Cr(VI) adsorption capacity of SB biochar was found to be 54.745 mg/g. The adsorption kinetics followed the pseudo-second-order (PSO) model (R² = 0.998), suggesting a chemisorption dominated process. The potential for adsorbent recyclability highlights the feasibility of SB derived biochar for sustainable Cr(VI) remediation in wastewater treatment. Therefore, this study underscores the environmental and economic benefits of repurposing industrial waste into high-performance adsorbent materials.