Quasi-Random Lattice Model for Electrolyte Solutions: State of Art and Future Perspectives

Abstract

In this work, the Quasi-Random Lattice (QRL) model is summarized and critically discussed, in order to outline its potentialities and limitations, in perspective of future developments. QRL primarily focuses on the mean activity coefficient of ionic solutions, the model having first been developed in order to provide practical equations, able to involve a minimal number of unknown or unpredictable quantities. QRL at present depends on one adjustable parameter (at given pressure and temperature), experimentally known for many common salts either symmetric or asymmetric, and corresponding to a well-defined concentration, which also sets the upper limit of applicability of the model. For aqueous electrolytes, the concentration-parameter ranges from 1 M to 8 M (about). In the following it will be seen that, although belonging to the class of simplified approaches, QRL can provide very interesting results since its simple parametrisation is more significant, from a theoretical point of view, than so far recognized. A general overview of the QRL theory will first be presented. Then, some preliminary results will be discussed, in particular concerned with volumetric and thermal properties of electrolyte solutions.