Activated Halloysites as Alternative Adsorbents for Crude Cottonseed Oil Bleaching

ABSTRACT This study aimed to modify and characterize natural halloysite using six activation methods and to evaluate their performance in the bleaching of neutralized crude cottonseed oil (NCO), in comparison with a commercial bleaching earth (CBE). Among the modified samples, acid‐activated halloysite (HS‐AA) exhibited the highest specific surface area (114.01 m 2 /g), while surface and pore properties varied significantly depending on the activation method. Scanning electron microscopy revealed notable alterations in tubular morphology, whereas X‐ray diffraction patterns indicated peak broadening, suggesting partial loss of interlayer water. Fourier‐transform infrared spectroscopy showed higher crystallinity and reduced impurity levels in HS‐AA and control (HS‐CN) samples. The treated oils were evaluated in terms of oil loss, color parameters, bleaching efficiency, peroxide value, UV‐specific absorbance, and free fatty acidity. The results demonstrated that thermally activated (HS‐TA), acid‐activated (HS‐AA), and oxalic acid‐activated (HS‐OA) halloysites exhibited promising adsorption performance. Phytosterol and tocopherol analyses indicated minimal nutrient losses in oils treated with HS‐TA and CBE. Overall, HS‐TA is proposed as a simple, cost‐effective, and efficient adsorbent for oil bleaching. Further optimization of activation conditions is recommended to enhance its performance.