# Study and Evaluation of Equivalent Conductivities of [SiO(OH)3]− and [SiO2(OH)2]2− in NaOH-Na2SiO3-H2O Solutions at 277.85 K to 308.45 K

## TL;DR

This study measures the conductivity of two silicate ions in solution at different temperatures to better understand their behavior in electrolyte systems.

## Contribution

The paper introduces a new conductivity model and experimentally determines the equivalent conductivities of two silicate species over a temperature range.

## Key findings

- Equivalent conductivities of SiOOH3− and SiO2OH22− were measured from 277.85 K to 308.45 K.
- A conductivity model for high-alkaline mixed electrolytes was established and validated.
- The study provides insights into how temperature and solution composition affect silicate electrolyte conductivity.

## Abstract

The equivalent conductivities of two aqueous silicate species, SiOOH3− and SiO2OH22−, are fundamental to understanding many physico-chemical phenomena of silicate materials in electrolyte solutions. These phenomena include diffusion, adsorption, and phase transformations. But significant inconsistencies have been presented in published equivalent conductivities of the two silicate aqueous ions. Also, little work has so far been undertaken to discuss how aspects, such as temperature and solution composition, may influence electrolytic conductivity of silicate aqueous solutions. This work presents the equivalent conductivities of the two silicate species, measured with electrochemical impedance spectroscopy (EIS) from 277.85 K to 308.45 K. A conductivity model for mixed electrolytes of high alkaline was first established. This model was then verified with the electrolyte conductivities of NaOH-H2O solutions and NaOH-Na2CO3-H2O solutions. Next, the equivalent conductivities of SiOOH3− and SiO2OH22−, were calculated by solving the overdetermined equation groups for different temperatures, based on electrolyte conductivities of NaOH-Na2SiO3-H2O solutions. The accuracy of both calculations and measurements are examined in depth from various viewpoints. This work presents essential inputs for quantitatively understanding multiple physico-chemical properties of silicate materials in electrolyte solutions.