Novel ecofriendly cation exchange membranes for low-cost electrodialysis of brackish water: Desalination and antiscaling performance

Electrodialysis (ED) has been widely used in desalination, and reducing related costs for brackish water (BW) desalination is the key for yielding it a more competitive technology. Ion-exchange membranes (IEMs) are the core of ED process. The complex preparation process of matrix materials for IEMs is not only an important reason for the high cost of IEMs, but also an important factor regarding environmental protection. This study presented an ecofriendly and simple method for preparing homogeneous cation exchange membranes (CEMs) for BW desalination by ED. Novel homogeneous CEMs were successfully prepared with polysulfone as the skeleton material, polyvinylpyrrolidone (PVP) as hydrophilic agent, and sodium dodecylbenzene sulfonate (SDBS) as functional material. The combined effects of PVP and SDBS were successfully used to strengthen membrane structure and properties. The results of membrane strength and structural examinations showed that the combined effects were the key to the stable existence of functional groups in these CEMs for a novel CEM design idea. These membranes were successfully used in ED and compared with commercial CEMs. The current efficiency of prepared CEMs, commercial Astom CEM, and commercial Tingrun CEM were 93.9, 94.8, and 90.4%, respectively, with the desalination rate >90% at an initial salt concentration of 5 g/L. The comprehensive efficiency of the prepared CEMs for removing salt was better than that of Tingrun CEM, while a little lower than that of Astom CEM. In ED operations for 30 cycles, all properties of the prepared membranes for removing salt were stable. This study conclusively revealed bright prospects for preparing ecofriendly CEMs and improving CEM performance in low-cost ED for BW desalination.