Effect of particle size on oil adsorption efficiency using untreated lemon peel adsorbents

The disposal of waste cooking oil (WCO) presents significant environmental risks, impacting soil, water, and ecosystems. This study explores the feasibility of lemon peels (LP), an abundant biowaste as a green adsorbent for oil removal from water. LP adsorbents were prepared at three different particle sizes which is 150 µm, 300 µm, and 425 µm, and the properties is analysed using Fourier Transform Infrared Spectroscopy (FTIR) and N2 adsorption-desorption analysis. Batch adsorption tests were performed to examine the effects of contact time (5–20 min), adsorbent size (150 - 425 µm), adsorbent dosage (0.4 – 1.0 g) and oil-to-water ratio (1:12– 1:4) toward the WCO removal efficiency. The FTIR results indicated the consistent presence of key functional group such as hydroxyl, carbonyl, and ester groups across all adsorbents, with no significant changes between different particle sizes. Analysis of surface area showed that LP-150 exhibited the highest surface area (14.69 m²/g) and pore volume (0.0119 cc/g), contributing to its superior oil adsorption capacity (6.5 g/g). Overall, this study demonstrates that untreated LP is a promising natural adsorbent for WCO removal, and that adjusting particle size significantly enhances its adsorption efficiency.