Determination of ionic strength due to magnesium sulfate heptahydrate in water by means of its permittivity in the microwave range

The ionic strength (I) of a solution is a measure of the concentration of ions or a measure of the intensity of the electric field in a solution. In water treatment, the ionic strength allows the determination of total dissolved solids concentrations. In this work, different concentrations of MgSO4*7H2O in water are considered. This produces several levels of ionic strength. This varies from 0 M to 0.20 M. The ionic strengths of liquid samples are determined by means of their permittivities in the microwave frequency range. The dielectric constants do not exhibit significant differences within the measured frequency range; however, the loss factors show significant differences at low frequencies. The loss factors at 500 and 915 MHz are used to determine the ionic strength due to MgSO4*7H2O. The relationships between ionic strength and loss factor obey to second-grade polynomials. The results presented in this work contribute to the development of tools that allow the monitoring of water in real time and in a non-invasive way.