The relationship between acidic activation and microstructural changes in montmorillonite from Heping, China

The montmorillonite sample from Heping, China had been studied by chemical analysis, XRD, IR, AFM and MAS NMR. The results showed that acid concentration had much influence on surface structure of montmorillonite. When the acid concentration reached 2 M, the Q3Si structure in silica–oxygen tetrahedron recombined, some Q3Si structure in montmorillonite transformed to distortion Q3Si structure and Q4Si structure. However, the structure of Al had no changes, according with the observation results of atomic force microscope. The Brønsted acid site of montmorillonite increases with the accretion of the concentration of acid activation, while oversize concentration of acid activation will decrease the surface site of montmorillonite.