| Summary: | Nano-TiO<sub>2</sub> has always been one of the most important topics in the research of photocatalysts due to its special activity and stability. However, it has always been difficult to obtain nano-TiO<sub>2</sub> with high dispersion, a small particle size and high photocatalytic activity. In this paper, nano-TiO<sub>2</sub> powder was prepared by combining the high-gravity technique and direct precipitation method in an impinging stream-rotating packed bed (IS-RPB) reactor followed by Fe<sup>3+</sup> in-situ doping. TiOSO<sub>4</sub> and NH<sub>3</sub>·H<sub>2</sub>O solutions were cut into very small liquid microelements by high-speed rotating packing, and the mass transfer and microscopic mixing of the nucleation and growth processes of nano-TiO<sub>2</sub> were strengthened in IS-RPB, which was beneficial to the continuous production of high quality nano-TiO<sub>2</sub>. Pure TiO<sub>2</sub> and iron-doped nano-TiO<sub>2</sub> (Fe-TiO<sub>2</sub>) were obtained in IS-RPB and were investigated by means of X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) and Brunauer−Emmett−Teller (BET) analysis, which found that pure TiO<sub>2</sub> had a particle size of about 12.5 nm, good dispersibility and a complete anatase crystal at the rotating speed of packing of 800 rpm and calcination temperature of 500 °C. The addition of Fe<sup>3+</sup> did not change the crystalline structure of TiO<sub>2</sub>. Iron was highly dispersed in TiO<sub>2</sub> without the detection of aggregates and was found to exist in a positive trivalent form by XPS. With the increase of iron doping, the photoresponse range of TiO<sub>2</sub> to visible light was broadened from 3.06 eV to 2.26 eV. The degradation efficiency of gaseous toluene by Fe-TiO<sub>2</sub> under ultraviolet light was higher than that of pure TiO<sub>2</sub> and commercial P25 due to Fe<sup>3+</sup> effectively suppressing the recombination of TiO<sub>2</sub> electrons and holes; the highest efficiency produced by 1.0% Fe-TiO<sub>2</sub> was 95.7%.
|
|---|