Thermal diffusion and thermoelectric phenomena in mixtures of electrolytes’ aqueous solutions and colloidal solutions

Abstract

Background. This work investigates thermoelectric phenomena in solutions of mixtures of electrolytes, which also include colloidal solutions. Thermoelectric and thermal diffusion phenomena in solutions of simple binary electrolytes have been studied in detail, and then there are not enough works devoted to the study of these phenomena in solutions of several electrolytes’ mixtures. Therefore, due to the possibility of using liquid electrolytes and their mixtures in thermoelectrochemical cells designed for direct conversion of low-potential thermal energy into electrical energy, these studies are relevant. Materials and methods. Standard methods are used to measure the coefficient of thermoelectric EMF of solutions of mixtures of ionic electrolytes and colloidal solutions. The analysis of the obtained experimental results is carried out within the framework of the thermodynamics of irreversible processes. Results and conclusions. Based on the analysis of the ratio for the thermodiffusion potential difference obtained in the framework of the thermodynamics of irreversible processes, it is shown that the value of the thermoelectric EMF of such solutions in the initial state is determined by the charged particles of the solution, which have the highest values of the product of the transfer number by the transfer heat. Experimental measurements in solutions of mixtures of ionic electrolytes, colloidal solutions confirm this assumption. It also follows from the analysis of experimental results that when the ratio between the components of an electrolyte mixture changes, its thermoelectric force tends to the value that the component of the mixture having the highest concentration has. This effect is due to the increasing value of the transfer numbers of charged particles with an increase in their concentration.

Keywords

• thermoelectric effect
• thermal diffusion effect
• ionic electrolyte
• colloidal solution
• heat of transfer