Effects of di-ions structure of the core layer ionomer on anion exchange membrane characteristics of anti-protein fouling and electrodialysis desalination

Abstract

To investigate the effects of di-ions structure of the core layer ionomer on anti-protein fouling and electrodialysis (ED) desalination performance of the tailored anion exchange membranes (AEMs), three highly conductive structural-controlled ionomers containing aliphatic bridging cage quaternary di-ammoniums, aliphatic liner quaternary di-ammoniums, and aromatic quaternary di-ammoniums respectively have been synthesized. With the help of the previously established bi-directional in-situ interpenetration method, a series of double-sided anti-fouling AEMs were successfully fabricated from the gradient cross-linked anti-fouling thin layer CA(2% SA-0.10Ca) and the tailored ionomers. These AEMs have basic and electrochemical properties suitable for ED applications, and significant anti-protein fouling ability. The results of the ED desalination evaluations at high current density with salted egg white confirm further that DABCO-MeI-CA having aliphatic-bridging-cage-di-ions with the best electrochemical properties displays the best ED performance (desalination rate (DR) = 32.16%, energy consumption (EC) = 0.27 kWh kg−1) and good ED stability. Its ED performance is better than that of commercial AMX, with an increase of 20.74% in DR and a reduction of 34.15% in EC. Protein biuret detections verify no protein-through-membrane pollution occurred in the tests. The properties of DABCO-MeI-CA are promising for high current density ED desalination of organic macromolecule-contaminated salted systems.