Enhanced Desalination Performance by a Novel Archimedes\nSpiral Flow Channel for Flow-Electrode Capacitive Deionization

Abstract

As\nan emerging desalination technology, flow-electrode capacitive\ndeionization (FCDI) has aroused extensive attraction due to its advantage\nof pseudoinfinite adsorption capacity. However, some problems still\nremain in the traditional FCDI devices, i.e., its streaming and seeping\nquality which has severely limited the progress. Herein, some improvements\nwere achieved by changing the direction of saline water in spacer.\nFurthermore, the Archimedes spiral flow channel model was introduced\nto improve the flow behavior of carbon slurry in the FCDI unit cell\nfor the first time, which has vastly boosted the desalination performance\nof FCDI devices. The computational fluid dynamics (CFD) simulation\nrevealed the more uniform velocity distribution and longer residence\ntime of carbon slurry in spiral flow channels to enhance the desalination,\nwhile the flow rate of carbon slurry in a straight line is faster\nbut slower in the corner of serpentine flow channels, causing a negative\neffect on the desalination performance. After long-term continuous\ndesalination in 3.5 g L^–1 NaCl solution at 2.4 V,\n99.88% of salt removal efficiency was achieved with a superior salt\nremoval rate of 4.06 μmol cm^–2 min^–1 and 98.9% charge efficiency for the spiral flow channel FCDI device,\ndemonstrating a stable desalination performance.