Diffusion dialysis-concept, principle and applications

Diffusion dialysis (DD) is an ion-exchange membrane (IEM) separation process driven by concentration gradient and has been applied for separation and recovery of acid/alkali waste solutions in a cost-effective and environmentally friendly manner. This review of DD covers the principles, models, applications (strong acid/weak acid/alkali separation and recovery), and its integration with other techniques, such as electrodialysis, ion exchange membrane-electrowinning, continuous membrane extraction, vacuum membrane distillation, and ceramic membrane micro-filtration. Notably, different factors including properties of the membranes, nature of the waste solution and running conditions are discussed and correlated with the DD performances.