Abstract
Recently, redox-mediated electrodialysis has emerged as a promising desalination technology. The unique feature of redox-mediated electrodialysis is to intervene in water stream channels in a redox flow battery system leading to desalination via a sustainable redox reaction. However, one of obstacles in the redox-mediated electrodialysis is low desalination capacity due to the limited cell voltage of around 1.2 V based on a narrow potential window of water. Therefore, this study aimed to improve the desalination performance of RFD. First, we adapted the organic supporting electrolytes for a redox reaction to extend the operational cell voltage. Second, the energy recovery process was introduced to improve the energy efficiency of the redox-mediated electrodialysis. As the major results, 1) the stable cell voltage was increased to 3.5 V by using the organic electrolyte for the sustainable redox reaction. 2) a significant improvement in the desalination performance was found, which is a 40-fold improvement in the salt removal rate of the redox-mediated electrodialysis compared to the system with aqueous supporting electrolyte. Moreover, the energy recovery process led to a 30% reduction in energy consumption. The results envision that the introduction of organic electrolytes in the redox-mediated electrodialysis can open new opportunities in the practical application including desalination and electrochemical resource recovery with an improved desalination performance via extension cell voltage and energy recovery process.
