The unmodified Kapok fiber demonstrated an adsorption efficiency of 50.64%. However, modification via the incorporation of calcium oxide through an esterification process enhanced the material's hydrophobicity, increasing the adsorption efficiency to 53.56%. In advanced methods, [PERSON] et al. [19] explored the use of commercial resins (A26 OH and IRA900 Cl) for free fatty acid removal without alkali chemicals during food oil refining. The study showed that at 35 \({}^{\circ}\)C, A26 OH removed up to 25.5% of free fatty acids, significantly outperforming IRA900 Cl. Adsorption studies aligned with the Langmuir isotherm model, indicating a monolayer adsorption mechanism. The reviewed literature demonstrates the versatility of diverse adsorbents, such as activated carbon, natural materials, and advanced resins, in the effective removal of polar compounds from used cooking oil. These findings contribute to improving the quality of recovered used cooking oil for reuse and furthering the development of sustainable and efficient purification technologies. Banana peel adsorbents are not only effective in purifying used oil but also demonstrate significant potential in various water treatment processes, including the removal of heavy metals, organic pollutants, and dyes. Their application in wastewater treatment has been widely studied, highlighting their efficiency in pollutant adsorption. Research by [PERSON] et al. [20] showed that when banana peel hydrothermal carbon was modified with a KOH solution, it exhibited an adsorption capacity of 42.92 mg/g and a removal rate of 86.84% for Pb\({}^{2+}\). Similarly, a study by [PERSON] et al. [21] demonstrated that modified banana peel effectively removed both Pb\({}^{2+}\) and Cd\({}^{2+}\), with an efficiency exceeding 99.9%. Further supporting the applicability of banana peel adsorbents in heavy metal removal, [PERSON] et al. [22] found that chemically activated banana peel biochar effectively removed Cr\({}^{5+}\) from aqueous solutions, significantly lowering its concentration in wastewater. Beyond heavy metal removal, banana peel adsorbents have also been extensively studied for their ability to remove cationic dyes (basic dyes), which are widely used in the textile and pharmaceutical industries. Their high adsorption efficiency for these dyes is attributed to their negatively charged surface under neutral to slightly basic pH conditions. For instance, [PERSON] et al. [23] reported that banana peel powder achieved an adsorption efficiency of 62.5% for methylene blue at an optimized pH of 6. Similarly, [PERSON] et al. [24] found that banana-peel-based activated carbon removed 93% of crystal violet from aqueous solutions within just 10 min of contact time. In addition to laboratory-scale experiments, banana peel adsorbents have also shown effectiveness in real industrial wastewater applications. [PERSON] et al. [25] reported that the removal efficiency of dyes in actual textile effluent remained significant, indicating the practical potential of banana peel adsorbents for industrial dye removal. Furthermore, desorption studies revealed that about 95% of the adsorbent could be recovered through a simple acid-base treatment, suggesting its feasibility for regeneration and reuse in multiple adsorption cycles. These studies collectively highlight the potential of banana-peel-based adsorbents as a sustainable, cost-effective, and highly efficient material for wastewater treatment. This study explores an innovative waste-to-resource approach aimed at contributing to sustainable development goals, addressing critical waste management issues, and advancing green technologies. The focus of this initiative is to transform banana peel waste generated by the banana chip industry into valuable porous adsorbents for the purification and recovery of used palm oil within the same industry, promoting a circular production system.