A novel capacitive electrode based on TiO2-NTs array with carbon embedded for water deionization: Fabrication, characterization and application study

Abstract To enhance the structure stability of conventional capacitive deionization (CDI) electrode, this work intends to provide a facile preparation of Titania nanotubes (TiO2-NTs) based electrode with carbon imbedded for capacitive deionization application. The TiO2-NTs array is obtained through anode oxidation method on the titanium substrate, then carbon precursors were induced into the nanochannels of TiO2-NTs carrier by the vacuum pressure and transferred to carbon capacitor through anaerobic pyrolysis process. Such structure possesses a unique combination with hollow carbon fibers as layer binders to fix the upper carbon spheres onto TiO2-NTs substrate. The as-prepared electrode revealed an excellent mechanical stability, electrosorption ability and electroconductibility as well as a favorable hydrophilicity especially after acid modification. This paper also investigates the influence of various operational parameters on the capacitive deionization process, including feed temperatures, flow rates and initial salt concentrations. The electrosorption kinetics is also analyzed within the deionization process, which shows the novel electrode presents a better sorption rate as well as a higher sorption capacity of 13.11 ± 0.58 mg/g at 1.2 V and 500 mg/L feed concentration. Furthermore, the removal principles of CDI electrode under multi-ion circumstance are compared and discussed depending on existing studies.