Abstract:
This study investigated the enhanced removal of diclofenac (DCF) from aqueous solution using chemically activated biochar derived from betel nut husk, an abundant agro-byproduct across South and Southeast Asia. Biochar (BC) was synthesized via tube furnace pyrolysis, and modified with alkali (BC-AL) and acid (BC-AC), and comprehensively characterized using XRD, FTIR, SEM-EDX, and BET surface area analysis. BC-AL exhibited notable adsorption performance, achieving 70.52% DCF removal within 180 min, compared to 50.39% for BC-AC and 30.66% for BC. Adsorption kinetics followed the PSO model (R2 = 0.99). Equilibrium data were evaluated by the Langmuir, Freundlich, and Temkin isotherm models (R2 = 0.95-0.99), yielding maximum adsorption capacities of 11.79, 7.24, and 5.31 mg g-1 for BC-AL, BC-AC, and BC, respectively. The adsorption mechanism involves synergistic contributions from electrostatic attraction, hydrogen bonding, and pi-pi electron donor-acceptor interactions. This study demonstrates that alkali-activated betel nut husk BC is a promising adsorbent for the effective removal of DCF from contaminated water, while offering a valuable pathway for the beneficial utilization of agricultural waste.
