Electrochemical desalination coupled with energy recovery and storage

Abstract

Abstract This paper presents the performance of a dual-purpose Zinc|ferricyanide desalination battery for simultaneous desalination and energy storage operations. The zinc|ferricyanide battery consists of an anode chamber with a zinc electrode immersed in ZnCl2(aq) electrolyte, a cathode chamber with a graphite electrode and electrolyte solution of K3[Fe(CN)6](aq) and K4[Fe(CN)6](aq), as well as a middle chamber with saline water to be desalinated. These chambers are separated by anionic and cationic exchange membranes, respectively. A series of experiments were conducted to study the impact of charging and discharging cycles on desalination-salination rates, power storage, and discharge rates at different charging capacities. The electrochemical cell was also characterized in terms of power density and desalination performance under various conditions. Results from this study confirm that the electrochemical battery desalination method has the potential to store energy and the charging-discharging cycles of the battery can provide a mechanism for desalination, which is achieved free of energy consumption. A desalination rate of 30.3% can be achieved during a 12-hr discharge period, which decreased the salinity levels from 41.2\xa0g/L to 28.7\xa0g/L. This result indicates that the process is also suitable for pre-desalination or pretreatment of high saline waters, which is a major challenge for current membrane processes.