Structural Alteration of Montmorillonite by Acid Activation and its Effect on the Decolorization of Rapeseed Oil

Low-temperature atmospheric calcination is a new technology for solving the current environmental issues associated with activated clay production. In this study, the structural alteration of montmorillonite during the production of activated clay was investigated by this new technology. The results revealed that the increase in temperature aggravates the destruction of montmorillonite layers, which mainly constituted octahedral sheets due to the continuous dissolution of cations in the sheets, with relatively stable tetrahedral sheets. Activated montmorillonite layers became curled and stacked in disorder, which was different from that in the original. The maximum acidity of 230 mmol/kg was achieved at an optimum temperature of 200°C. Under this condition, the specific surface area and total pore volume increased from 78.4 m 2 /g to 226 m 2 /g and from 0.107 cm 3 /g to 0.318 cm 3 /g, respectively. With the improvement in the decolorization ability of the clay, the absorbance of the rapeseed oil decreased to 0.867 from 4.070.