A. Maia, R. Angélica, R. Neves, H. Pöllmann, C. Straub, K. Saalwächter.
Use of 29Si and 27Al MAS NMR to study thermal activation of kaolinites from Brazilian Amazon kaolin wastes.
Appl. Clay Sci. 87, 189-196 (2014).
The study of thermal activation of kaolinite at various temperatures to produce highly reactive metakaolinite
fromBrazilian Amazon kaolinwasteswas studied using 27Al and 29Si magic angle spinning nuclearmagnetic 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, SEMand 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 resultswere
confirmedwhen zeolite NaAwas synthesized frommetakaolins produced at temperatures used in this