A novel porous asymmetric cation exchange membrane with thin selective layer for efficient electrodialysis desalination

Abstract

Ion exchange membranes (IEMs) are widely used in various electrochemical fields. Generally, identifying a solution for the trade-off between ion conductivity and dimensional stability is crucial for the further development of IEMs in the electrodialysis (ED) process. This study aimed to prepare a novel type of cation exchange membrane for electrodialysis desalination. Different from the previous cation exchange membranes with the thick and dense cross-section structure, the as-prepared asymmetric composite membranes in the present work composed of a thin and dense skin layer and a porous support layer via the pore-filling process of the skin layer of the porous poly (ether sulfone) (PES) membrane. Benefiting from such structural features, effective ion transport and dimensional stability were simultaneously achieved in the case of low ion exchange capacity. Ultimately, the optimal sulfonated poly (ether sulfone)-poly (ether sulfone) (SPES-PES) composite membrane simultaneously achieved ion transport enhancement, low swelling rate at 80 °C, and better mechanical stability compared to pure sulfonated poly (ether sulfone) (SPES) membranes. When applied to ED, the prepared 40 %SPES-PES membrane exhibited more excellent desalination performance (91.9%), higher current efficiency (127.5%), and lower energy loss (5.55 Kw·h·kg−1) compared to commercial membrane.