The hydrothermal preparation of sodium silicate

Abstract

A comparatively high steam pressure should be used to give complete sodium silicate formation from the starting materials. Moreover, a higher steam pressure is required in the case of using sodium carbonate than on using sodium hydroxide. Sodium metasilicate hydrate prepared under a low steam pressure (2.5 atmy appears to be amorphous in nature while that prepared from sodium hydroxide or sodium carbonate at a higher steam pressure is crystalline and very similar to the metasilicate hydrate with the formula Na2Si03. 9H20. However, the metasilicate prepared from sodium carbonate appears to be poorly crystalline due to the presence, in the prepared material, of an appreciable amount of sodium carbonate.