Enhanced Diclofenac Removal From Aqueous Solution Using Activated Betel Nut Husk Biochar

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.