Mass transfer characteristic research on electrodialysis for desalination and regeneration of solution: A comprehensive review

Abstract

Electrodialysis (ED) is a very mature membrane separation technology. Due to its energy-saving, environmental adaptability and flexibility, ED is used in different industries for desalination and regeneration of solutions. In order to capture the internal operation mechanism of ED, and to optimize the performance and structure of ED, the mass transfer model is very significant. This paper introduces the principle and application scope of ED and the influencing factors of mass transfer in ED. The concentration difference and the moisture migration are key factors. Also, the main modeling methods of ED are summarized. Among them, the modeling methods based on Nernst-Plank equation are the most common used, because they are easy to understand and independent to describe migration process of each ion. The scope of application and shortcomings of different methods are also described in this paper. Then, a lot of work has been conducted to introduce the development of the theoretical models of ED at different solution concentration levels, as well as the limitations and optimization potentials in the development process. According to the different concentration levels of solution, the purpose of modeling the mathematical model will change. Under low concentration, the mass transfer models are more used to describe the basic concentration or velocity distribution, while the theoretical models under ultra-high concentration in liquid desiccant air conditioning system are used to predict the impact of moisture transfer on the performance of the ED. The theoretical mass transfer model will be a powerful optimization tool for ED.