Improving electrosorption performance in membrane assisted capacitive deionization cells using asymmetric electrodes configuration

Membrane capacitive deionization (MCDI) is an emerging salt treatment technology that performs beyond the capabilities of traditional capacitive deionization cells due its ability to mitigate unwanted ion expulsion events. We present a dynamic model for observing the concentration response of deionization cells configured in a recirculating batch setup. The model consists of two volumes representing the deionization cell and the reservoir where salt storage and mixing respectively occur. The model was used to fit a typical MCDI cell made up of two similar electrodes each with potential of zero charge (E_PZC) values of ∼-0.2 V vs saturated calomel electrode (SCE), and an asymmetric MCDI cell with respective anode and cathode E_PZCs at ∼-0.2 and ∼+0.2 V vs. SCE. The model predicts increases of up to 50% and 10% in capacity and efficiency, respectively, for the asymmetric MCDI cell.