1. Supplementary H2O2 generation in capacitive deionization with a three-phase architecture and its application in simultaneous desalination and organics control.
- Author
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Wu, Junsheng, Chen, Zihan, Lv, Fangjie, Li, Jiahui, and Li, Yang
- Subjects
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DEIONIZATION of water , *OXYGEN reduction , *SALINE waters , *ATMOSPHERIC diffusion , *WATER purification , *ADSORPTION capacity - Abstract
• A novel capacitive deionization with a three-phase architecture (T-CDI) was proposed. • Cathodic oxygen reduction was enhanced in T-CDI without affecting desalination. • SAC value and H 2 O 2 generation were 14.91 mg/g and 25.55 mg/L, respectively. • Simultaneous desalination and organics control was achieved by T-CDI/UV. • Applicability of T-CDI in long-term operation was investigated. Cathodic oxygen reduction, as a Faradaic side reaction, has been proven to be thermodynamically favorable for H 2 O 2 generation in capacitive deionization (CDI), which may provide a greener manner for organics control alongside desalination. However, the low levels of dissolved oxygen (DO) in saline water and its potential Faradaic degradation of carbon-based electrodes limit the H 2 O 2 generation in the conventional CDI (C-CDI). Herein, a novel three-phase CDI architecture (T-CDI) was proposed to simultaneously achieve stable desalination and supplementary H 2 O 2 generation. Unlike C-CDI architecture, T-CDI was open-ended at the cathode side, where porous nickel foam was used as current collector and air diffusion layer. Accordingly, a stable gas–liquid-solid three-phase interface was created inside the cathode, thus enhancing the diffusion and utilization of atmospheric air and preventing the damaging effects of excessive DO on the electrode. A stable electrosorption and electrocatalysis performance for T-CDI was obtained by regulating electrode hydrophilic-hydrophobic properties, comparing with other CDI configurations, and altering operating conditions. The salt adsorption capacity and H 2 O 2 accumulative concentration were 14.91 mg/g and 25.55 mg/L, respectively. Furthermore, the simultaneous desalination and organics control in T-CDI were investigated with the assistance of UV irradiation (T-CDI/UV). When treating NaCl and sulfamethazine (SMR) mixture solution, T-CDI/UV significantly reduced the irreversible electrode organic fouling and improved the desalination stability. Additionally, the potentially hazardous SMR was effectively removed alongside desalination. Finally, the long-term operation of T-CDI demonstrated that the generated H 2 O 2 cannot induce an additional substantial deterioration in desalination stability. The techno-economic assessment showed T-CDI was economically competitive compared with C-CDI. This study provides insights into the synergy of non-Faradaic and Faradaic processes and further diversifies the application of CDI in water treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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