Low-cost continuous measurement system to learn the relationship between electrical conductivity and temperature in brackish waters

Abstract

This work proposes the use of inexpensive experimental equipment to allow engineering students and professionals to observe and deepen their understanding of the different relationships between water quality parameters. In the case considered in this work, the experimental equipment is designed to observe and enable an understanding of the relationship between the electrical conductivity (EC) of brackish water and its temperature (T). The experimental design includes an embedded Arduino Nano microcontroller system. Importantly, the design is based on flexible and open-source software and hardware, facilitating its modification for other related studies. In this work, the effect of T on the EC of sodium chloride and potassium chloride solutions at different salinities was deter-mined. A mixture of these two salts with magnesium chloride to represent the main components of seawater was also studied. It is shown that the relationship between T and EC, at different concentra-tions of the salts, fits a linear model which includes different equations resolved with the data taken during the empirical study. EC conductivity is a measure of the current conducted by ions present in the water (phenomenon of conductors of the second kind) and depends on the concentration and nature of the ions and the temperature and viscosity of the solution, as reported in ISO 7888-1985.