Thermal analysis of montmorillonite modified by imidazolium

Abstract

In order to improve the performance of sodium (Na) montmorillonite (MMT), in this study, 1-hexadecyl-2,3-dimethylimidazolium bromide was synthesized and used as a cationic surfactant for the organic modification of sodium MMT. The modification effect of pH was investigated, and the structure of the imidazole organic modifier was characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopy (FTIR). In addition, the modified sodium MMT was systematically confirmed by FTIR and X-ray diffraction. The results showed that the imidazolium surfactant successfully intercalated into the galleries of MMT and enlarged the (001) d spacing of MMT. It was observed that the d (001) peaks largely shift to the left with decreasing pH, indicating low pH-facilitated intercalation, and its effect reached the best at pH 3, where the interlayer distance between MMT platelets increased from 1·31 to 3·52 nm. Thermogravimetric analysis showed that the modified sodium MMT exhibited excellent thermal stability; the onset and the maximum decomposition temperature were 343 and 406°C respectively.