Enhanced desalination performance in flow electrode capacitive deionization with nitrogen doped porous carbon

Abstract

As a promising continuous desalination technology, flow electrode capacitive deionization (FCDI) has received considerable attention. However, poor conductivity and dispersion of the traditional active carbon (AC) flow-electrode limit the properties of FCDI. In order to achieve excellent desalination performance, a flow electrode with good dispersion, low resistance, and high salt adsorption capacity is essential. In this study, nitrogen-doped porous carbon (NPC) was synthesized through one-step pyrolysis process of ethylenediamine tetraacetic acid tetrasodium (Na₄EDTA). The prepared NPC material showed a high specific surface area (1168.4 m² g⁻¹), appropriate nitrogen and oxygen doping, excellent hydrophilicity and low resistance. At 1.2 V applied voltage, the desalting experiments showed that the FCDI system based on a NPC flow electrode exhibited a higher average salt removal rate of 0.0459 mg cm⁻² min⁻¹, and the salt adsorption capacity (148.93 mg g⁻¹) based on the NPC flow electrode was about 2.3 times larger than that of AC. Furthermore, after continuous desalination cycling for long periods of time, the salt removal efficiency and average salt removal rate remained stable. The results of this study may be useful for the future exploration of high performance electrode materials for FCDI systems.