Biosorption of lead from water using fruit and vegetable peels: characteristics, adsorption kinetics, and isotherms
摘要
The growing concern over food waste has highlighted the urgent need for sustainable mitigation strategies. Valorization of food waste offers a promising approach to address both environmental and economic challenges while supporting the circular economy. This study investigated the potential of using pumpkin (PP), yellow melon (YMP), banana (BP), and watermelon peels (WMP) as low-cost biosorbents for lead (Pb) removal from water. Batch adsorption experiments using Pb nitrate solution were conducted over three days at room temperature (22 ± 2 °C). Key parameters—including initial Pb(II) concentration (10–5000 mg/L), equilibration time (1 min–3 days), and biosorbent dosage (0.83–6.66 g/100 mL)—were optimized. Maximum adsorption efficiency was achieved with an equilibration time of three days, a biosorbent dosage of 6.66 g/100 mL, and a Pb(II) concentration of 5000 mg/L. Under these conditions, the highest Pb adsorption capacities were 89,607 µg/g (PP), 88,961 µg/g (YMP), 89,542 µg/g (BP), and 89,398 µg/g (WMP), corresponding to removal efficiencies of 99.56%, 98.85%, 99.61%, and 99.33%, respectively. Adsorption behavior of BP and WMP followed the Langmuir isotherm, while the Freundlich model best described PP and YMP. Kinetic analysis showed that the pseudo-second-order model effectively captured the sorption kinetics (R2 > 0.99). Physicochemical characterization revealed that WMP possessed the highest specific surface area and porosity, correlating with superior Pb affinity. FTIR and SEM analyses confirmed structural and surface changes before and after adsorption, validating the biosorption effectiveness of the tested peels. These findings highlight the potential of fruit peels as eco-friendly biosorbents and warrant further investigation for large-scale water treatment applications.