Photocatalytic Degradation of Methylene Blue Dye by Electrospun Binary and Ternary Zinc and Titanium Oxide Nanofibers

Abstract

Synthetic dyes, dispersed in water, have harmful effects on human health and the environment. In this work, Ti and/or Zn oxide nanofibers (NFs) with engineered architecture and surface were produced via electrospinning followed by calcination. Calcination and subsequent cooling were operated at fast rates to generate porous NFs with capture centers to reduce the recombination rate of the photogenerated charges. After morphological and microstructural characterisation, the NFs were comparatively evaluated as photocatalysts for the removal of methylene blue from water under UV irradiation. The higher band gap and lower crystallinity were responsible for the lower photocatalytic activity of the ternary oxides (ZnTiO3 and Zn2TiO4) towards the degradation of the dye. The optimal loads of the highly performing binary oxides were determined. By using 0.66 mg mL−1 wurtzite ZnO for the discoloration of an aqueous solution with a dye concentration of 15 µM, a higher rate constant (7.94 × 10−2 min−1) than previously reported was obtained. The optimal load for anatase TiO2 was lower (0.33 mg mL−1). The corresponding rate constant (1.12 × 10−1 min−1) exceeds the values reported for the commonly used P25–TiO2 benchmark. The catalyst can be reused twice without any regeneration treatment, with 5.2% and 18.7% activity decrease after the second and third use, respectively.

A Mini Review of Photocatalytic Effects of Nano TiO_2 and an Analysis of Their Effectiveness

“…The size of particles was 18.9 nm. After 40.2 minutes, the rate of decomposition was 81.7% [27]. MB dye has been tested with THNF-400 (Titanium Dioxide hollownanofibre).…”

Photocatalytic Activity of TiO2 Nanoflower Thin Films under UV Irradiation

“…That is, the presence of adjacent Ti vacancies stabilizes the oxygen vacancies [29]. S.S. Al-Shamali [30] reported photodegradation rate of 90% of MB dye in TiO2 photocatalyst with pH values ranging from 4 to 8. A comparable study was undertaken by a number of other researchers, as shown in Table 2.…”

Perovskite Nano-Powder and Nano-Film Catalysts in Mineralization of Aqueous Organic Contaminants through Solar Simulated Radiation

“…The report did not rationalize the effect of the pH value. Other reports have described ZnTiO 3 nanopowders and nanofibers in the photodegradation of methylene blue with no reference to the pH effect [18,55]. In another report [56], ZnTiO 3 supported on clays and zeolites adsorbed more methylene at higher pH values within the range of 2-10.…”