The effect of ultrasound on Na–A zeolite synthesis based on sodium aluminosilicate gels and solid materials

Abstract

To explain some aspects about the mechanism of zeolite synthesis from reagent materials, law temperature (100 oC) hydrothermal reaction was performed in alkali solutions by using sonochemically-assisted pre-treatment method. This pretreatment method reduces the formation times of zeolites. Clear-to-the-eye sodium aluminosilicate gels and solid sodium aluminosilicate mixtures were used as raw materials. By using sodium aluminosilicate gels, it is observed that after hydrothermal treatment and sonication up to 10 minutes samples exhibit a rise in the crystallinity of Na-A zeolite up to 1.44 times, compared to a sample without sonication. When solid components as raw materials were used, the application of ultrasound irradiation and hydrothermal treatment resulted in the replacement of Na-A zeolite crystals to Na-X zeolite, which is a more stable zeolitic phase. In both cases Na-A zeolite was not detected in the synthesized products by using only sonication without the using of hydrothermal treatment. It was observed that the Na-A zeolite crystallization level is higher for samples which were obtained from the raw material of aluminosilicate gel.