Anti-fouling anion exchange membrane for electrodialysis fabricated by in-situ interpenetration of the ionomer to gradient cross-linked network of Ca-Na alginate

• Published in: Desalination 2021-06, Vol.505, p.115005, Article 115005
• Main Authors: Xie, Hengxin, Pan, Jiancong, Wei, Biaowen, Feng, Jun, Liao, Shijun, Li, Xiuhua, Yu, Yigang
• Format: Article
• Language: English
• Subjects: Anion exchange membrane; Anti-fouling; Ca-Na alginate; Electrodialysis; In-situ interpenetration
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2021.115005

We developed a series of anti-fouling anion exchange membranes (AEMs) by in-situ interpenetration of an ionomer of N-methylimidazole ionizing poly(2,6-dimethyl-1,4-phenylene oxide) (IM-QPPO) to lateralized gradient cross-linked hydrogel of Ca-Na alginate (CA). The CA surfaces repel negative-charged organic pollutants because of their inherent hydrophilicity and electronegative property. SEM and EDX characterizations reveal that the micron-sized anti-fouling CA layers are bonded firmly with the ionomer bulk by the interpenetration. The anti-fouling AEMs have qualified basic properties of thermal stability, water uptake and swelling ratio, area resistance and permselectivity for electrodialysis (ED) processes. IM-QPPO-0.10CA with optimal interpenetrating structure exhibits the highest current efficiency (η) of 88.88% and the lowest energy consumption (EC) of 2.53 kWh kg−1 NaCl among the group, which are comparable to those of commercial AMX (η = 89.38%, EC = 2.20 kWh kg−1 NaCl). IM-QPPO-0.10CA shows the strongest anti-fouling ability, which is confirmed by the lowest ascent speed of transmembrane voltage and no irreversible membrane-structure damages during the fouling tests. Moreover, the fouled IM-QPPO-0.10CA recovers 99.60% of the origin η value with an EC increase of 0.10 kWh kg−1 NaCl after immersion in NaCl solution. The properties of IM-QPPO-0.10CA are promising for the application of anti-fouling ED AEMs. A series of anti-fouling anion exchange membranes (AEMs) were successfully fabricated by in-situ interpenetration of IM-QPPO to the lateralized gradient cross-linked network of Ca/Na alginate hydrogels. IM-QPPO-0.10CA with optimal interpenetrating structure exhibits the strongest anti-fouling ability and the comparable current efficiency to that of commercial AMX. The results are promising for the application of anti-fouling ED AEMs. [Display omitted] •In-situ interpenetration process of IM-QPPO to Ca-Na alginate hydrogel was created.•Influences of interpenetration structures of AEMs on electrodialysis were disclosed.•Ca-Na alginate surface provides IM-QPPO-0.10CA with stable anti-fouling property.•IM-QPPO-0.10CA gives current efficiency comparable to that of commercial AMX.