Parametric study of multichannel desalination battery for low-energy electrochemical deionization of brackish water

Abstract

Multichannel desalination batteries (MC-DBs) have been utilized to enhance the performance of battery electrodes by decoupling the electrodes (side channels) and target brackish water (middle feed channel), enabling independent control of the channels. Nevertheless, the technological level of MC-DB is at an infancy, and further understanding of the role of operating conditions is required for its practical application. In this study, a parametric investigation of the applied current, cutoff voltage, and solution concentration fed to the feed and side channels was performed to improve the electrochemical deionization of MC-DB to achieve low-energy brackish water desalination. With presence of 20 times concentration difference between the feed and side channels, the MC-DB retained approximately 76% of the initial desalination capacity even upon a ten-fold increase in the current density (5–50 A·m−2). Moreover, MC-DB exhibiting a salinity gradient minimized the resistance penalty resulting from the low-salinity of brackish water. A high battery-utilization ratio (>80%) was achieved at various feed water concentrations. Up to 73% of the energy consumed for desalination was recovered through modification of the current and cutoff voltage. Consequently, under the optimized conditions, the MC-DB system could desalinate low-salinity brackish water with a substantially reduced energy consumption of 5.5 kJ·mol−1.