Resin-enhanced rolling activated carbon electrode for efficient capacitive deionization

Capacitive deionization (CDI) has emerged as an efficient process for low-salinity desalination, but electrode materials remain a major bottleneck. This study presents new hybrid CDI electrodes that for the first time directly incorporate ion exchange resins into activated carbon electrodes via a rolling press method. These thin and integrated electrodes showed superior performance over traditional membrane-electrode assemblies. When used in 2.0 g/L NaCl solution they increased desalination efficiency by 29-35% and 70-76% compared with activated carbon electrodes and carbon cloth electrode, respectively. The difference further increased to 41-47% and 121-131% when a lower concentration of 0.5 g/L NaCl was used. The resin-embedded carbon electrodes showed an electrosorption capacity of 12.7 and 18.3 mg NaCl/g electrode in 0.5 and 2.0 g/L NaCl solution, respectively. The charge efficiency ranged from 85-87%, and energy consumption was reduced by 25%. The high performance of the resin-enhanced activated carbon electrodes in CDI is attributed to pre-concentration of target ions and blockage of co-ions especially in low salinity conditions. This approach holds a good potential for CDI development, and further studies are needed for corrosion inhibition and capacity improvement.