Abstract
In this study, TiO2 nanotubes (TNTs) were fabricated on a Ti sheet following the anodic oxidation method and were decorated with reduced graphene oxide (RGO), graphene oxide (GO), and bismuth (Bi) via electrodeposition. The surface morphologies, crystal structures, and compositions of the catalyst were characterized by field emission scanning electron microscopy, Auger electron spectroscopy, X-ray diffraction, photoluminance spectra, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The TNTs loaded with RGO, GO, and Bi were used in a continuous-flow system as photocatalysts for the degradation of methylene blue (MB) dye. It was found that the TNTs are efficient photocatalysts for the removal of color from water; upon UV irradiation on TNTs, the MB removal ratio was ~89%. Moreover, the photocatalytic activities of the decorated TNTs were higher than that of pristine TNTs in visible light. In comparison with TNTs, the rate of MB removal in visible light was increased by a factor of 3.4, 3.2, and 2.9 using RGO-TNTs, Bi-TNTs, and GO-TNTs, respectively. The reusability of the catalysts were investigated, and their quantum efficiencies were also calculated. The cylindrical anodized TNTs were excellent photocatalysts for the degradation of organic pollutants. Thus, it was concluded that the continuous-flow photocatalytic reactor comprising TNTs and modified TNTs is suitable for treating wastewater in textile industries.
Highlights
TiO2 nanotubes (TNTs) synthesized via anodization have generated significant attention in recent years [1,2] because of their extraordinarily technological importance and improved photoelectric properties for a wide variety of applications such as solar cells [3], photocatalysis [4], gas sensors [5,6], water splitting [7,8], and developing functional surface devices [9]
The photocatalytic activities of the TNTs loaded with reduced graphene oxide (RGO), graphene oxide (GO), and Bi were explored systematically for degradation of methylene blue (MB) as a sacrificial agent in a continuous-flow photocatalytic reactor
The structures and morphologies of the synthesized TNTs and modified TNTs were examined by field emission scanning electron microscopy (FESEM)
Summary
TiO2 nanotubes (TNTs) synthesized via anodization have generated significant attention in recent years [1,2] because of their extraordinarily technological importance and improved photoelectric properties for a wide variety of applications such as solar cells [3], photocatalysis [4], gas sensors [5,6], water splitting [7,8], and developing functional surface devices [9]. Bismuth on the surface of TiO2 can trap photogenerated electrons, reducing the recombination of electron and hole, and can improve the visible-light photocatalytic activity of TiO2 [17]. As compared with immobilized TiO2 particles, TNTs possess a higher aspect ratio and a larger specific surface area, which suggest the fabrication and design of TNTs may be a more attractive and fruitful endeavor to achieve the photocatalytic degradation of organic compounds. TNTs serve as flexible, supporting, and stable substrates and are more suitable for the design of photocatalytic reactors. They are used in a continuous-flow photocatalytic reactor. The photocatalytic activities of the TNTs loaded with RGO, GO, and Bi were explored systematically for degradation of methylene blue (MB) as a sacrificial agent in a continuous-flow photocatalytic reactor. The continuous-flow reactor was found to be suitable for treating wastewater effluent in textile industries
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