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.

Research highlights▶ Diffusion dialysis (DD) has the advantages such as low consumption of energy, low installation/operating cost and cleaner nature and thus is receiving considerable attention today. ▶ Diffusion dialysis is reviewed intensively for the first time, including its principle, models, applications as well as the corresponding integration processes. ▶ The spiral wound membrane module for diffusion dialysis is described for the first time. ▶ The perspectives (including the advantages and limitations, challenges and opportunities) for the development of diffusion dialysis is presented.