Influence of Mechanochemical Pretreatment on the Activation Behavior of Bentonite With Respect to Oil Bleaching Performance

Abstract

This study systematically investigates the effect of mechanochemical pretreatment followed by controlled acid activation on the bleaching performance of bentonite in palm oil. Raw bentonite was mechanically milled for different durations to reduce particle size and induce lattice disorder, creating highly accessible sites for subsequent sulfuric acid activation. Structural and physical modifications, including increased structural disorder and particle size reduction, were evaluated using XRD, XRF, and particle size analysis. The optimally activated bentonite (120 min milling, 2 M H₂SO₄, 10 wt.% solid to acid ratio, 1 wt.% dosage, 90°C, 30 min) achieved a maximum bleaching efficiency of 98.5%. Adsorption isotherms showed that pigment removal follows the Freundlich model, indicating multilayer adsorption on a heterogeneous surface. This work demonstrates that combining mechanochemical and acid activation effectively enhances bentonite's structural and functional properties, providing a practical strategy for high-performance oil bleaching.