Highly permselective and conductive composite anion exchange membranes QPT@PE for electrodialysis desalination

Abstract

This article tailored an octadecyl hydrophobic long chain modified series-connected aliphatic di-cation ionomer (named QPT), and developed a series of pore-filling composite anion exchange membranes (AEMs) QPT@PE with improved permselectivity (P), conductivity and mechanical properties using ultra-thin microporous polyethylene (PE) membrane with high mechanical strength as substrate, which well utilizes the strong interaction between the flexible hydrophobic long side chains and the pore wall to of the substrate resulting from their similar basic moieties. Interestingly, a composite membrane 15 % EtOH QPT@PE with suitable ionomer loading and blending aggregation structure simultaneously has significantly improved mechanical properties and best electrochemical properties with tensile strength of 58.6 MPa, elongation at break of 132.4 %, P reached 96.3 %, membrane area resistance low to 1.3 Ω cm2. Naturally, the composite AEM exhibits excellent performance in electrodialysis (ED) testing, including current efficiency of 94.1 %, salt flux of 85.6 mg m−2 s−1, and low energy consumption of 1.50 kWh kg−1 NaCl. All ED performance indicators of 15 % EtOH QPT@PE are superior to those of commercial AMX, and its preparation cost is less than $30.0 m−2, indicating that it has great potential in long-term ED seawater desalination applications.