Application of activated carbon from durian peel activated with potassium hydroxide and microwave as an adsorbent for the purification of used cooking oil

Durian (Durio zibethinus) is a seasonal fruit widely consumed in Indonesia.This high consumption results in a large amount of durian peel waste, which is often unused and underutilized.Durian peel, which contains lignocellulosic components, can be used as a precursor for adsorbents or activated carbon in the purification of used cooking oil.This study aims to enhance the adsorption capacity of activated carbon derived from durian peel by combining chemical activation using potassium hydroxide (KOH) with subsequent physical activation using microwaves.The experimental procedure consisted of several stages, including carbonization of durian peel, chemical activation using KOH, followed by microwave-assisted physical activation, and analysis of the purified oil.The variables investigated were the carbon-to-KOH ratio (w/v) (1:5, 1:10, 1:15, and 1:20) and the adsorbent concentration (5%, 10%, 15%, and 20%).Microwave activation was carried out at a power of 560 W for 10 min, followed by oven drying of the activated carbon.The adsorbent particle size was 150-200 mesh, with an adsorption time of 120 min and a stirring speed of 250 rpm.The results indicate that a carbon-to-activator ratio (w/v) of 1:20 produced the best activated carbon from durian peel, with a moisture content of 4.07%, ash content of 4.91%, carbon content (C) of 67.56%, and a surface area of 400.68 m² g⁻¹.Under optimal conditions, the free fatty acid (FFA) content decreased by 92.84%, while the peroxide value decreased by 53.01%.