Free Fatty Acid Adsorption of Crude Palm Oil by Modified Fly Ash

agriTECH
Vol 45, No 4 (2025)

This study used modified fly ash as a material to adsorb free fatty acid in Crude Palm Oil. One or two types of modification treatments in previous studies were used to investigate the effect on the absorption process. Therefore, this study focused on the capacity of the modified fly ash in adsorbing FFA with varying concentrations and durations of adsorption. Modification of fly ash began through leaching process using hydrochloric acid (HCl), followed by activation using hydrogen peroxide (H₂O₂), and reactivation using cocamidopropyl betaine (CAPB) surfactant. Scanning Electron Microscope Energy Dispersive X-Ray (SEM-EDX) is used to analyze the morphology and elements, while a Gas Sorption Analyzer (GSA) is used to analyze the pore radius, surface area, and pore volume of modified fly ash. Based on SEM-EDX result, fly ash had an amorphous shape with silicon (32.15%) and oxygen (50.29%) as the major elements. While GSA showed that the surface area, total pore volume, and average pore diameter were 15.34 m²/g, 0.02 cc/g, and 3.23 nm, respectively. Furthermore, modified fly ash had adsorption efficiency and capacity of 44.38%±0.21 and 140 mg/g±0.21, respectively. Then, adsorbent mass of 6% w/w and adsorption duration of 60 minutes recorded as the optimal condition of FFA adsorption process using fly ash. The maximum permissible FFA in cooking oil based on Standar Nasional Indonesia (2019) was 0.30%. Because of that, multi-stage adsorption was carried out to reduce the FFA in order to comply with Standar Nasional Indonesia (2019). The adsorption with twice repetition can produce CPO with FFA < 0.30% (initial FFA content of 1.2%). Due to the reduction level of FFA, the yield of the CPO obtained from each step was ±60-80%. This study could be applied in industry to reduce the FFA content and enhance the CPO quality.