Single modular flow-electrode capacitive deionization using modified Prussian blue analogues as cation intercalation...

Area of Science:

• Materials Science
• Electrochemistry
• Environmental Engineering

Background:

• Conventional flow-electrode capacitive deionization (FCDI) faces limitations due to ion back-diffusion, impacting long-term operational stability.
• Prussian blue analogues (PBAs) offer potential for improved electrochemical and rheological properties in deionization systems.

Purpose of the Study:

• To develop and evaluate a hybrid flow-electrode capacitive deionization-cation intercalation deionization (PFCDI-CID) system.
• To address ion back-diffusion challenges in FCDI by integrating cation intercalation deionization (CID).
• To investigate the desalination performance and mechanism of the novel PFCDI-CID system.

Main Methods:

• Integration of cation intercalation deionization (CID) with flow-electrode capacitive deionization (FCDI).
• Utilization of modified Prussian blue analogues with enhanced properties for flow electrodes.
• Performance evaluation under single-cycle (SC) mode and continuous operation for 12 hours.

Main Results:

• The PFCDI-CID system achieved a high charge efficiency of 89.77% and energy-normalized salt removal of 0.69 mol kJ⁻¹ in single-cycle mode.
• Stable desalination performance was maintained over 12 hours of continuous operation, with average charge efficiency at 88.44%.
• The desalination mechanism primarily involves Na⁺ intercalation, with a minor contribution from electro-sorption.

Conclusions:

• The developed PFCDI-CID system effectively mitigates ion back-diffusion, overcoming a key limitation of conventional FCDI.
• The system demonstrates stable and efficient desalination, broadening the application scope of FCDI technology.
• Modified Prussian blue analogues are suitable for developing advanced deionization systems with enhanced performance.