Purification of Used Cooking Oil Using Adsorption Method

Used cooking oil is a hazardous waste that poses environmental and health concerns due to the formation of toxic compounds during repeated heating. However, it can be recycled into valuable industrial products such as grease after proper purification. This study investigates the purification of used cooking oil using adsorption with different adsorbents, including bleaching earth (BE), coconut shell charcoal (CSC), anhydrous magnesium sulfate (MSA), and silica gel (SG). Adsorption experiments were performed under atmospheric conditions at 80 °C with varying adsorbent dosages (5–30 g per 200 mL oil). The purification performance was evaluated in terms of Free Fatty Acid (FFA) and moisture content reduction, according to SNI 7709:2019 standards. The results showed that MSA (20 g) achieved the highest FFA reduction (41.26%), closely followed by BE (25 g) at 40.34%. For water content, MSA (30 g) achieved the highest removal efficiency (95.02%), followed by BE (25 g, 88.45%), SG (25 g, 86.64%), and CSC (10 g, 70.56%). Overall, BE at 25 g was identified as the best adsorbent, providing significant reductions in both FFA and water content while also improving oil color. The purified oil meets the requirements as base oil for grease production.