Pb(II) Ions Removal Using Lemon-Derived Activated Carbon as an Adsorbent for Industrial Wastewater Treatment

In this study, lemon peel–derived activated carbon (LPAC) was prepared and evaluated as a sustainable adsorbent for the removal of Pb(II) ions from aqueous solutions. Batch adsorption experiments were systematically conducted to investigate the influence of key operational parameters, including pH, temperature, adsorbent dose, contact time, and stirring speed. The results revealed that adsorption performance was strongly pH-dependent, with maximum capacity (476 mg/g) and removal efficiency (95.2%) achieved at pH 6. Temperature studies indicated that adsorption was endothermic, with optimal removal efficiency (95.2%) at 45 °C, while higher temperatures slightly reduced performance. Increasing the adsorbent dose improved Pb(II) removal up to 1.0–1.5 g/100 mL, reaching 98.0%, beyond which efficiency remained constant. Contact time experiments showed rapid initial uptake, with equilibrium established at 30 minutes, corresponding to a maximum removal of 98.0%, after which desorption effects caused efficiency to decline. Stirring speed optimization indicated the best performance at 300 rpm (98.8% removal), with excessive agitation reducing adsorption efficiency. Under optimized conditions, LPAC was compared with commercial activated carbon (CAC). LPAC demonstrated superior adsorption capacity (476 mg/g) and higher removal efficiency (95.2%) compared to CAC (360 mg/g and 82.4%, respectively), owing to its well-developed porosity and abundant surface functional groups. These findings highlight LPAC as a cost-effective, eco-friendly alternative to commercial activated carbon for Pb(II) removal from industrial wastewater, offering both high efficiency and sustainable waste valorization