The study of thermal activation of kaolinite at various temperatures to produce highly reactive metakaolinite from Brazilian Amazon kaolin wastes was studied using 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR). The wastes used in the current study came from the Capim and Jari regions in northern Brazil. The mineralogical and chemical characterizations of Jari kaolin (KJ) waste were performed by XRD, FTIR, DTA–TGA, SEM and chemical analyses. The results indicate that the Jari and Capim kaolins (KC) wastes are composed primarily of kaolinite and that KJ is composed of a typical kaolinite with a low degree of structural order. The ideal temperature to produce highly reactive metakaolinite is 600 °C for KJ and 700 °C for KC, suggesting that the degree of structural order of kaolinite has a definite influence on its dehydroxylation temperature. These results were confirmed when zeolite NaA was synthesized from metakaolins produced at temperatures used in this work.
Maia, A. A. B., Angélica, R. S., Neves, R. F., Pöllmann, H., Straub, C., & Saalwächter, K. (2014). Use of 29 Si and 27 Al MAS NMR to study thermal activation of kaolinites from Brazilian Amazon kaolin wastes. Applied Clay Science, 87, 189-196. https://doi.org/10.1016/j.clay.2013.10.028