Ion-Exchange Preparation of Low-Silica Hydroxide Solutions for Colorimetric Determinations of Total Silica

Abstract

ATTEMPTS to determine small concentrations of total silica colorimetrically by applying the method of Straub and Grabowski¹, following solubilization of the silica by boiling with hydroxide, have been frustrated by the interference of the silica present in either the sodium or potassium hydroxide used as the solubilizing agent. In studying this problem, the possibility of preparing a hydroxide solution by passing a salt solution through the hydroxide-form of a quaternary-base ion-exchange resin was investigated. The fact that complete conversion from the salt to the hydroxide is not required for the analytical method is a recommendation of this approach ; a salt solution more concentrated than is normally amenable to ion-exchange treatment may be used as the starting material in order to produce a moderately concentrated hydroxide solution.