Crystallization sodium metasilicate solution

This method is appropriate for growing single crystals of compounds that have a medium or low solubility and cannot be recrystallized because of a disproportionation in the mother liquor. The reaction is not carried out in a gel medium (sodium metasilicate or an organic gel), as in the well-known gel technique 1 rather a saturated solution of the compound itself is used as reaction medium.2 Thus crystals of a compound AX can be grown by slowly and simultaneously adding a solution of a compound AY and a solution of a compound BX to a saturated solution of AX according to the reaction... 

Regardless of the t)q)e of soluble metal silicates used, they are subject to the same molecular speciation in aqueous solution resulting in a mixture of monomeric tetrahedral ions, oligomeric linear or cyclic silicate ions, and polysilicate ions. Sodium metasilicate, an example of a soluble metal silicate, can be prepared in anhydrous form or in the presence of water of crystallization as the penta- or nona-hydrate. It is readily soluble in water [8]. 

Derivation Crystals from solutions obtained by heating silica or sodium metasilicate with sodium hydroxide. Intermediate in composition between ortho- and metasilicates, less alkaline than sodium orthosilicate. 

In contrast to household detergents, indnstrial detergents contain much greater amounts of silicate. When dissolved in water, they give solutions of mnch higher pH than domestic formulations [1]. This is the domain of anhydrons sodium metasilicate. It is described by the chemical formula NajSiOj, which corresponds to a one-to-one molar ratio of silicon oxide and sodium oxide (Na20 Si02 = 1 1). It has a crystalline strnctnre and forms monoclinic, colorless crystals or a white powder... 

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