Optimization of Mixing Activated Carbon and Fly Ash as Adsorbents for Reducing Free Fatty Acid Content and Acid Value in Used Cooking Oil

Abstract

Used cooking oil is a waste product from frying oil that has been reused multiple times, leading to a decline in quality, characterized by a rancid odor and a darker color. This condition can pose health risks if the oil is reused without proper treatment. One of the purification methods for used cooking oil is adsorption using adsorbent materials. This study aims to determine the optimum conditions for the addition of activated carbon and fly ash to reduce the levels of free fatty acids and acid value in used cooking oil, as well as to calculate the percentage reduction of these two parameters. The used cooking oil treated through adsorption was tested for free fatty acid content and acid value. The results showed that the combination of activated carbon and fly ash was effective in reducing free fatty acid content and acid value. Optimum conditions were achieved with the addition of 20% adsorbent by sample weight, at a heating temperature of 50 °C for 30 minutes. The percentage reductions in free fatty acid content, acid value, and water content were 14.0%, 21.8%, and 0.27%, respectively.