Experimental study on the structure of spacer in a flow-electrode capacitive deionization

Abstract

The flow-electrode capacitive deionization (FCDI) technology has recently been actively studied as a means of easy scale-up for mass desalination based on the principle of an electric double-layer capacitor. In this study, we investigated the structural characteristics of a porous insulating spacer, which determines the desalting performance. The effect of parameters, such as thickness, porosity, wettability, and flow rates of saltwater (FRw) have been investigated. As a result, for FRw ≥2 mL/min the desalting efficiency increases with decreasing the spacer’s thickness, but for FRw < 2 mL/min the optimum thickness was found to be 0.6 mm in terms of desalting efficiency. Utilizing a 0.3 mm thickness spacer lead to the best configuration in the FCDI setup based on the current efficiency criteria. The results show that the optimum porosity for the porous spacer was 0.56 in terms of desalting efficiency and salt removal rate while the spacer with 0.44 porosity has the best performance based on the current efficiency. In particular, wettability did not affect performance. It is observed that desalting efficiency increases as FRw decreases.