Influence of poly(ionic) liquid incorporation within resin wafer electrodeionization for reduced energy consumption in brackish water desalination

Resin Wafer Electrodeionization (RW-EDI) is recognized as a promising technology for energy-efficient desalination of brackish water. However, RW-EDI is limited by energy requirements for the treatment of high-salinity feeds which prevent the large-scale deployment of this technology. Several material factors influence the resulting performance of RW-EDI. Current state-of-the-art wafers rely on a nonconductive polymer binder to ensure mechanical stability of resin wafers. However, a robust ionic polymer could improve resin wafer conductivity and energy efficiency of RW-EDI systems. Herein, this research studied the influence of ionic polymers within RW-EDI resin wafers. Specifically, polymer ionic liquid-based (PIL) ionic polymers were incorporated within ion exchange resin wafer formulations to enhance ion conductivity during RW-EDI operation. Two different resin wafer formulations were developed incorporating phosphonium-based PILs. These new resin wafer formulations were tested in a benchtop RW-EDI system at varied applied voltages. The results demonstrated that PIL loading had a major influence on the mechanical stability and conductive properties of the resin wafer as well as the RW-EDI performance. Resin wafers incorporating PILs exhibited an order of magnitude increase in ion conductivity (2.21 x 10-2 mS/cm) as compared to conventional polyethylene resin wafers (8.64 x 10-3 mS/cm). In the RW-EDI system, a 9.3 % decrease in specific energy consumption was achieved when PIL with 2.5 g loading of phosphonium-based PIL was employed, as compared to conventional polyethylene-based resin wafers. The results indicate that PIL ionic polymers can significantly improve energy efficiency within RW-EDI systems. The results also suggest that future studies should investigate additional ionic polymer materials for additional energy efficiency improvements within RW-EDI systems.

Automated summary

Research shows that the use of ionic polymers can improve the ion conductivity and energy efficiency of resin wafers, thus enhancing the performance of resin wafer electrodeionization (RW-EDI) systems. In the experiment, different ionic polymers were used, and the results demonstrated that resin wafers incorporating these polymers had higher ion conductivity and significantly lower specific energy consumption in the RW-EDI system, compared to traditional resin wafers.