| Abstract Scope |
Despite sepiolite from the United States is superior in terms of quantity and quality, there is little research on it, especially for the changes of structure and morphology during heat treatment. In this paper, sepiolite from Nevada was investigated by heat treatment from 200- 1000°C. The results were characterized by XRD, SEM, FTIR, and TGA/DTG. It was found that the sorption, zeolitic and coordinated water are removed successively at 104°C, 115°C and 296°C, with the sepiolite transferred into sepiolite tetrahydrate, sepiolite dihydrate and sepiolite dehydrate. The dehydration of the hydroxyls happened at 684°C, with the complete collapse of the sepiolite structure. Calcite and dolomite are completely decomposed into CaO at around 700°C. Finally, MgSiO3 was formed. The average diameter of sepiolite bundles decreases with the heating temperature increasing to 800°C but the shapes remain the same. After 800°C, the sepiolite bundles partly melt forming a porous structure after calcination. |