Effect of Carbon Slurry Interfacial Property on Electrochemical Capacitive Deionization Performance

Activated carbon is currently preferred as the active component for capacitive deionization in flow electrodes used in sustainable water treatment systems. Despite significant advancements in optimizing activated carbon, the flow electrode composition still includes a solvent. At present, this solvent typically matches the composition of simulated seawater to enhance the conductivity of the carbon slurry. However, when considering the carbon slurry as a monolithic material, salts of the same composition may influence the capacitive deionization performance through a co-ionization effect. In this study, two distinct types of activated carbon and distilled water were used to prepare flow electrodes composed entirely of carbon slurry. The focus was to investigate the variations in capacitive deionization performance caused by the physicochemical properties of the carbon slurry. The results indicate that the carbon paste made from activated carbon with a higher zeta potential (measured in distilled water) exhibits superior desalination efficiency of 98.7% and a capacitance contribution of 48.6%. Additionally, the salt content in the carbon paste can affect its stability, subsequently reducing the overall desalination performance. Therefore, it is essential to examine the carbon slurry as a whole, rather than concentrating solely on its active components.