Low energy cost high electrodialysis performance anion-exchange membranes for desalination

Abstract

Energy consumption (EC) and salt flux (J) are the two key parameters of the industrial electrodialysis (ED) devices. Increasing J usually increases EC. The challenge of a qualified ED anion-exchange membrane (AEM) is the dilemma of high J and low EC. Here we designed a series of poly(aromatic ethers) based AEMs with main-chain type quaternary ammoniums. The characterization results of structure and basic properties tell that the so-made AEMs are homogeneous, dense and defect-free, and show applicable ion exchange capacities (IECs), water uptakes (WUs), area resistances (Rarea s) and mechanical properties. The results of the ED tests clear that the current efficiency (η) values of the AEMs ED units are higher than 87.4% companying comparable or better EC than that of the commercial AEM TWEDA1 ED unit (J = 81.22 mg m–2 s–1, EC = 2.13 kWh kg–1) and J varying from 79.77 to 80.92 mg m–2 s–1. Especially, the ED unit of QPAEK (IEC = 1.14 mmol g–1) has an EC of 2.08 kWh kg–1. The tailored AEMs ED units have good comprehensive ED performances with relatively high J and low EC. These results reveal the potential of QPAEs for industrial ED processes.