CONDUCTOMETRY ANALYSIS – BENEFICIAL METHOD FOR DETERMINING THE CHEMICAL COMPOSITION OF ALKALINE SILICATE SOLUTIONS

Abstract

The study deals with the methodology for determining the chemical composition of alkaline silicate solutions. Nowadays, the most widely used method in industry is titration, using the color change of an acid-base indicator. This technique is very accurate for the determination of the total alkalinity (i.e., Na2O, K2O, or Li2O). However, a problem arises in the determination of the SiO2 content, since the color change of the methyl red indicator is very slow and therefore the equivalence point is unclear. The main aim of this work is to present the benefits of conductometric titration, where the equivalence point is indicated by a sudden change in the conductivity. The applicability of the method was verified with other analytical techniques, such as ICP-OES and gravimetric analyses. Their results confirmed the values of the obtained silicate module (the molar ratio of SiO2 and alkaline oxide) in the cases of sodium, potassium and lithium water glasses. Based on the obtained results, one can say that conductometry is a very promising method providing an accurate, fast and instrumentally undemanding chemical characterization of alkaline silicate solutions, usable even in a manufacturing process.