The waste from the processing of scooters kaolin in the Amazonian region of Brazil was subjected to a calcination process at 700°C for 2 h to obtain metakaolin, which, together with sodium hydroxide and sodium silicate, formed the reaction mixture.This mixture was subjected to an aging step (24 h at 60 rpm), and a subsequent hydrothermal process at 110°C for 10 h.By means of X-ray diffraction (XRD), differential thermal and thermogravimetric analysis (DTA/TG) and scanning electron microscopy (SEM) techniques, the crystallization of a single phase, faujasite (FAU) zeolite, was observed.
In the postsynthesis process, it was verified by means of XRD that the thermal stability of this structure persists up to a temperature of 600°C.At 800°C, the structure of FAU collapses.Beginning at 850°C, new nepheline phases are formed, and at 1000°C, nepheline and mullite Dice phases are formed.