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

Lukas Kalina; Vlastimil Bílek; Michaela Flídrová; David Markusík; Libor Topolář; Josef Fládr

doi:10.17222/mit.2024.1005

Lukas Kalina Brno University of Technology, Faculty of Chemistry, Purkyňova 118, 612 00 Brno, Czech Republic
Vlastimil Bílek Brno University of Technology, Faculty of Chemistry, Purkyňova 118, 612 00 Brno, Czech Republic
Michaela Flídrová Brno University of Technology, Faculty of Chemistry, Purkyňova 118, 612 00 Brno, Czech Republic
David Markusík Brno University of Technology, Faculty of Chemistry, Purkyňova 118, 612 00 Brno, Czech Republic
Libor Topolář Brno University of Technology, Faculty of Civil Engineering, Veveří 331, 602 00 Brno, Czech Republic
Josef Fládr Czech Technical University in Prague, Faculty of Civil Engineering, Thákurova 2077, 166 29 Prague, Czech Republic Prejem rokopisa – received: 2023-09-21; sprejem za objavo – accepted for publication:

DOI: https://doi.org/10.17222/mit.2024.1005

Keywords: conductometry, titration, chemical composition, 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.

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