Preparation and Photocatalytic Activity of TiO2 Nanotubes for Water Purification

Abstract

Self-organized TiO2 nanotubes (TNTs) were synthesized by anodization of Ti foil in an ethylene glycol-DI water electrolyte containing fluoride. The surface morphology, crystal structure, surface area and composition of the catalyst were analyzed by field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, BET analysis, and Raman spectroscopy. The analysis of variance (ANOVA) program was used to assess the effect of anodization parameters (such as NH4F concentration, voltage and time) on nanotube formation. The photocatalytic (PC) activity of the as-prepared catalyst was evaluated using methylene blue (MB) as a model pollutant. To increase the efficiency of the catalyst, a small external bias was applied during photoelectrocatalytic (PEC) degradation. The optimum voltage for the PEC process was 1 V. The anodized TNTs were excellent for the degradation of organics. The external voltage in the PEC process helped to reduce the recombination rate of photo-induced electrons and holes, which increased the formation of OH radicals consumed in the degradation of organic pollutants. Catalyst recycle experiment was performed for many cycles to evaluate the reuse efficiency of photocatalytic. To evaluate the photocatalytic degradation of dyes using TNTs, a continuous and batch experiments were carried out.