Calamondin Peel Waste-Derived Activated Carbon as a Biosorbent for Heavy Metal Removal from Aqueous Solutions

This research focused on utilizing agricultural waste, calamondin (Citrus madurensis) peel, to produce low-cost calamondin peel-based activated carbon (CPAC), initially for Pb(II) ion removal from simulated water. CPAC, prepared by carbonizing chemically treated peel waste at 400 ºC for 120 min, achieved 99% Pb(II) removal under optimized conditions: 5 ppm initial Pb(II) concentration, 0.03 g adsorbent dosage, 20 min shaking time at pH 7. Isotherm studies confirmed chemisorption, with a maximum adsorption capacity of 10.63 mg/g. Furthermore, CPAC demonstrated a removal efficiency of 31.01% to 49.29% for Cd, Cr, Cu, Mn and Zn in water samples collected from the Kelani river, Sri Lanka. These findings emphasize the viability of CPAC as a cost-effective, environmentally sustainable adsorbent for the remediation of heavy metal-laden water, thereby advancing sustainable waste management and environmental remediation.