[12] reported that fresh vegetable oils are mostly non-polar. However, during frying, complex chemical reactions produce polar compounds. Studies have shown that treatment methods can effectively lower levels of free fatty acids, peroxide values, and polar compounds in used cooking oils. These treatments improve the quality of oil, allowing it to be reused for various purposes. The efficiency of activated carbon can be further improved by optimizing activation methods, such as chemical or physical activation, and selecting suitable raw materials for its production. Building upon the application of bio-based adsorbents, [PERSON] et al. [13] investigated the potential of activated carbon derived from agricultural waste, specifically durian peel, for the purification of used cooking oil. The study demonstrated that this adsorbent effectively reduced both the peroxide value and free fatty acid content of the oil, thereby improving its reusability. Notably, the performance was significantly enhanced using H\({}_{2}\)SO\({}_{4}\)-impregnated biomass, achieving optimal results after 150 min of contact time. This treatment reduced the free fatty acid content to 0.0637% and the peroxide value to 0.41 meg O\({}_{2}\)/kg. Natural adsorbents have shown considerable potential for oil purification, as demonstrated by [PERSON] et al. [14], who evaluated the performance of zeolite and eggshell in treating used sunflower and palm oils. Their adsorption studies, conducted with dosages varying from 5 to 30 g per 100 mL of oil, revealed that NaOH-activated zeolite and heat-treated eggshell exhibited superior adsorption capacities and enhanced surface areas. Furthermore, an increase in the adsorbent dosage and contact time effectively reduced acidity and peroxide values, underscoring the efficiency of natural adsorbents in improving oil quality. Building on the application of natural materials, [PERSON] et al. [15] investigated the use of banana-peel-derived activated carbon for the reduction of free fatty acids (FFAs) in used cooking oil. Their study emphasized the influence of activation temperatures (600 \({}^{\circ}\)C, 650 \({}^{\circ}\)C, and 700 \({}^{\circ}\)C) on the adsorption performance. Batch adsorption experiments conducted with powdered activated carbon (200 mesh) demonstrated that the adsorption process conformed closely to the Freundlich isotherm model (R\({}^{2}\) = 0.97), suggesting effective physical adsorption. The maximum adsorption capacity of 27.404 mg/g was achieved at an activation temperature of 700 \({}^{\circ}\)C, underscoring the critical role of process optimization. The effectiveness of mineral-based adsorbents in regenerating used frying oils was further validated in a study by [PERSON] et al. [16]. This investigation compared the performance of silica gel, magnesium oxide, activated clay, and aluminum hydroxide gel. Among these materials, silica gel demonstrated superior efficacy in enhancing oil quality, albeit with a relatively limited adsorption capacity. Analysis using the Langmuir adsorption model determined a maximum adsorption capacity of 219 mg/g for silica gel in the removal of total polar materials. Similarly, zeolites have been extensively studied for polar molecule removal. [PERSON] et al. [17] investigated the application of activated natural zeolite for the adsorption of free fatty acids (FFAs) from low-grade cooking oil. Zeolite activated with 0.75 M NaOH exhibited superior efficacy in FFA removal compared to HCl-activated zeolite, particularly after calcination. Adsorption equilibrium studies conducted at 25 \({}^{\circ}\)C, 40 \({}^{\circ}\)C, and 80 \({}^{\circ}\)C revealed that the NaOH-activated zeolite adhered to the Freundlich isotherm model, signifying multilayer adsorption and demonstrating consistent performance across varying conditions. Additionally, bio-based materials have been extensively modified to enhance their adsorption capabilities. [PERSON] et al. [18] investigated the use of raw and modified Kapok-fiber-based adsorbents for the purification of used cooking oil.