Dissolution of aluminosilicates in hydrochloric acid solutions. I. Dissolution rates of cations and change in specific surface area of the residues

Abstract

Dissolution of aluminosilicates in weak hydrochloric acid solution was studied. In general, sodium ions were at first dissolved into the solution, and then aluminum ions began to dissolve after the dissolution of sodium ions was almost completed. The amount of sodium and aluminum ions dissolved was just equivalent to the amount of acid consumed. In the course of dissolution of both ions, dissolution of silicon was also observed. From these facts, it was suggested that silicon atoms were dissolved as the result of breaking of aluminosilicate structure, in contrast with the case of sodium and aluminum ions. Therefore, the dissolution of silicon atoms was due to a secondary effect. One silicon atom dissolved when 1.3 aluminum atoms dissolved in the case of sodium aluminosilicates No.1-6, which were synthesized in alkaline medium, while one silicon atom dissolved when 2.7 aluminum atoms dissolved in the case of No.7 and 8, which were synthesized in acid medium. It was therefore concluded that the samples synthesized in acid medium were neither sodium aluminosilicates nor sodium aluminum silicates but sodium aluminum aluminosilicates. It was also found that the degree of crystallization and adsorption volume of N2 gas on crystalline aluminosilicates decreased when these crystals were washed with acid solution.