Simultaneous Fractionation, Desalination, and Dye Removal of Dye/Salt Mixtures by Carbon Cloth-Modified Flow-electrode Capacitive Deionization

Abstract

The critical challenges of using electromembrane processes [e.g., electrodialysis and flow-electrode capacitive deionization (FCDI)] to recycle resources (e.g., water, salts, and organic compounds) from wastewater are the fractionation of dissolved ionic matter, the removal/recovery of organic components during desalination, and membrane antifouling. This study realized the simultaneous fractionation, desalination, and dye removal/recovery (FDR) treatment of dye/salt mixtures through a simple but effective approach, that is, using a carbon cloth-modified FCDI (CC-FCDI) unit, in which the carbon cloth layer was attached to the surface of each ion-exchange membrane (IEM). The IEMs and carbon-based flow-electrodes were responsible for the fractionation and desalination of dye and salt ions, while the carbon cloth layers contributed to the active membrane antifouling and dye removal/recovery by the electrosorption mechanism. Attributed to such features, the CC-FCDI unit accomplished the effective FDR treatment of dye/salt mixtures with wide ranges of salt and dye concentrations (5–20 g L–1 NaCl and 200–800 ppm methylene blue) and different dye components (cationic and anionic dyes) under various applied voltages (1.2–3.2 V). Moreover, the active membrane antifouling by virtue of the carbon cloth facilitated the excellent and sustainable FDR performance of CC-FCDI. The removal/recovery of dyes from the carbon cloth strongly depends on the characteristics of dye molecules, the surface properties of the carbon cloth, and the local pH at the IEM/CC interfaces. This study sheds light on the strategies of using multifunctional layer-modified FCDI units to reclaim resources from various high-salinity organic wastewater.

Coupling effects between metal–organic framework derivatives and oxygen-deficient TiO2 nanotubes: identified charge-transfer processes and photoelectric synergistic effect

“…However, eqn (12) was prevented from working due to the acidity of the system, so TC was directly oxidized. 56 The EPR spectrum of singlet oxygen (Fig.…”

“…9 Therefore, it is vitally important to identify substrates with distinctive structural characteristics to combine catalytic materials effectively. A variety of conductive substrates (nickel foam, 10 TiO 2 , 11 and carbon cloth 12 ) are widely mentioned in this field. TiO 2 as a semiconductor metal oxide makes it easy to synthesize the TiO 2 -NTs (TNTs) structure with adjustable shape, in which tubular structures are considered the most suitable method for achieving more significant surface area increases without increasing the geometric area.…”