Synthesis of Sodalite Zeolite from Alkaline Fusion of Kaolin and Crystallization at Low Temperature and Ambient Pressure

In this study, a sodalite-type zeolite (SOD) was synthesized through the alkaline fusion of kaolin and crystallized under ambient pressure conditions, without the need for autoclaves and high temperatures. The influence of the ratio between fused kaolin and water (g/mL) during crystallization was evaluated. The ratio of fused kaolin with NaOH to water at 1:10 g/mL resulted in the synthesis of zeolite with higher relative crystallinity (70.99%), which was affected by the concomitant formation of thermonatrite phase. Additionally, the zeolite showed a Si/Al ratio of 0.95 and Na/Al ratio of 1.00, and the aluminum atoms exhibited a configuration of perfect tetrahedra. Due to the absence of octahedral aluminum in the zeolitic structure and the charge-balancing cations being Na⁺ ions, the zeolite presented itself as a basic solid.