Synthesis and characterization of sodalite-type zeolite obtained from kaolin waste

Abstract

Zeolite products were synthesized from industrial waste from kaolin processing. The starting material was submitted to thermal treatment at 700 °C for 2 h. Synthesis processes were carried out by reacting kaolin waste with NaOH and an additional source of silica, in hydrothermal conditions, for SiO₂/Al₂O₃ molar ratios from 2 to 4, for 24 to 72 h of crystallization at 90 to 120 °C. The starting material was characterized by XRF, XRD, SEM, and TG/DSC, and the synthesized products were characterized by XRD, SEM, XRF, TG/DSC, FTIR, BET surface area, and pore diameter distribution. The product obtained at 90 °C for 48 h using the SiO₂/Al₂O₃ ratio of 3 showed the best result, forming sodalite as the only crystalline phase. From the characterization techniques, it was possible to confirm the formation of sodalite, observing the main aspects related to this zeolite.

Keywords:
zeolite; sodalite; kaolin waste