Simultaneous desalination and removal of organic pollutants in a novel bifunctional FCDI system: The enhancement by in-situ reutilization of chloride ions

A new system of flow electrode capacitive deionization coupled with in situ electro-oxidation (FCDI-EO) was constructed to achieve the degradation of organic pollutants while maintaining high desalination efficiency. The effects of different parameters of potential difference, electrolyte, and pH on the chloride removal performance of FCDI-EO and the removal performance of rhodamine B (RhB) were investigated. Under the optimal conditions of potential difference = 4 V, [Cl − ] = 500 mg/L, and pH = 4, the removal of chloride ions, RhB and total organic carbon (TOC) was as high as 88.74 %, 99.02 %, and 87.82 %, respectively. The quenching experiments showed that hydroxyl radicals ( OH) and reactive chlorine species (RCS) were involved in the FCDI-EO system. The liquid chromatography-mass spectrometry (LC-MS) analysis suggested the possible mineralization pathway of RhB. Furthermore, toxicity assessment analysis showed that the toxicity of the degradation intermediates of RhB decreased during the treatment. Overall, this study provides a promising process that reducing the generation of high-concentration saline water in desalination and in situ utilizing the Cl − gathered from the feed water. The findings of this study could provide useful guidance for the development of flow electrode capacitive deionization technology and organic pollutant control.