Synthesis and Characterization of Mesoporous Silica from Anorthite-Clay Mineral: Role of Mechanical Activation

Abstract

Mesoporous silica was prepared from anorthite-clay via mechanical activation (i.e., grinding) and selective acid leaching method. The pore characteristics of the mesoporous silica with different grinding time and acid treatment time were systematically characterized and compared with those prepared via heat treatment followed by acid treatment. Particle size, X-ray diffraction (XRD), BET surface area, thermal gravity (TG), and solubility analyses were carried out to characterize the samples. The XRD results showed that grinding and heat treatment dramatically altered the crystal structure of the samples, resulting in the change in weight loss curves of the corresponding samples from TG analysis. The results for pore size distribution of the prepared samples revealed that acid-treatment led to significant changes in the pore structure of the samples while grinding and heat-treatment without acid-treatment showed negligible influence on the pore structure. More specifically, acid-treatment increased the specific surface area of the ground and heat-treated samples regardless of acid-treatment. Furthermore, solubility tests for anorthite-clay samples showed that there is a positive relationship between the solubility of anorthite-clay and the specific surface area of mesoporous silica, indicating that the increase in the specific surface area of mesoporous silica was attributed to the increase in the solubility of anorthite-clay.