Highly conductive anti-fouling anion exchange membranes for power generation by reverse electrodialysis

Abstract

To address the challenges of low power density and membrane contamination experienced in reverse electrodialysis (RED) for capturing salinity gradient energy, we customized three anti-fouling anion exchange membranes (named QPD-Cx-CA) potentially having good conductivity and permselectivity simultaneously and investigated the influences of side auxiliary alkyl group (Cx, x is the carbon atom numbers of alkyl) tuning of core layer anion conductive ionomers on power generation and antifouling ability. QPD-Cx-CA were fabricated by double-direction in-situ interpenetration of the tailored series-connected 1,4-diazabicyclo[2.2.2]octane di-cation ionomers QPD-Cx to ultra-thin lateralized gradient cross-linked Ca-Na alginate (CA) hydrogels. The results of permselectivity tests in various salt solutions declare good salt tolerance of QPD-Cx-CA. Additionally, the moderate tuned junction and conductive bulk structures offer QPD-C4-CA and QPD-C1-CA excellent comprehensive power generation performances in the double-sided highly contaminated systems of various salinity gradients due to the inherent good salt tolerance, antifouling, permselectivity and conductivity. Especially, the maximum power density of QPD-C1-CA under the high-salinity system achieves 1.47 W m−2, which is 1.2 times that of commercial AMX and up to relatively high level in RED power generation. The results reveal their prospective application in power generation from natural river-seawater and high-salinity industrial wastewaters.