Study of the Thermal Stability of Faujasite Zeolite Synthesized from Kaolin Waste from the Amazon

Abstract

The waste from the processing of 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 phases are formed.

Mullite-Based Ceramics from Mining Waste: A Review

“…As a consequence of this process, a large amount of waste is generated, estimated at around 80% to 90% of the total volume of the exploited mineral [128]. This fact has prompted various investigations focused on the recovery of waste originating from the extraction of kaolin as a raw material in the manufacture of zeolites [129,130], molecular sieves [131] or cordierite [132]. The studies focused on the valorization of kaolin processing wastes in the manufacture of mullite-based ceramics are summarized below.…”

Effects of Thermal Treatment on Natural Clinoptilolite-Rich Zeolite Behavior in Simulated Biological Fluids

“…The conversion to the corresponding oxide was made by multiplying the element concentration with 1.8895 (Al 2 O 3 ), 1.4297 (Fe 2 O 3 ), 1.3392 (CaO), 1.6583 (MgO), 1.2046 (K 2 O), 1.3480 (Na 2 O), 1.2912 (MnO), and 1.6683 (TiO 2 ) [29]. The SiO 2 and loss of ignition (LOI) were determined by gravimetry [38]. A potash feldspar (BCS-CRM 376/1) certified reference material (Bureau of Analyzed Samples, Middlesbrough, UK) with a similar matrix to zeolite samples was analyzed for quality control purposes.…”

Kinetic study of the transformation of sodalite to nepheline

“…In the case of nepheline, its production from natural zeolites waste or from zeolites synthesized from waste appears to be one of the most promising routes. In this way, Han et al 13 reported on the manufacture of nepheline porous ceramics, with improved strength and well thermal insulation performance, from waste zeolite powders, while de Castro et al 14 described its production from fajausite prepared from kaolin waste.…”

“…In this way, Han et al 13 . reported on the manufacture of nepheline porous ceramics, with improved strength and well thermal insulation performance, from waste zeolite powders, while de Castro et al 14 . described its production from fajausite prepared from kaolin waste.…”