Advances in polymeric cation exchange membranes for electrodialysis: An overview

Polymeric cation exchange membranes (CEMs) have attracted enormous attention in various industrial and fundamental science domains in the last eight decades. CEMs are made of polymeric materials bearing covalently bound acidic functional groups fixed into the polymer backbone, which allow selective transport of cations, while anions are excluded due to the Donnan effect. The key metrics for developing polymeric CEMs include higher permselectivity and ionic conductivity, good chemical and thermal stability, and mechanical strength. These properties are influenced by anionic functional groups, structure, and the architecture of the polymer backbone. Recent research and progress in polymer science and engineering have been focused on the design and development of CEMs with various chemical structures and advanced functionalities. In this literature review, an overview of the recent development in polymeric CEMs is first provided. The design, fabrication techniques, and potential applications of homogeneous, heterogeneous, and surface-engineered CEMs for electrodialysis (ED) are discussed. A summary of the challenges and perspectives of this growing field is discussed at the end. • This review addresses the current status of the state-of-the-art cation exchange membranes (CEMs). • The progress in designing homogeneous, heterogeneous, and surface-modified CEMs are discussed. • It summarizes and compares the performances of the CEMs in ED processes. • Prospect for future research is proposed.