Abstract
Nano-TiO(2) 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(2) with high dispersion, a small particle size and high photocatalytic activity. In this paper, nano-TiO(2) 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(3+) in-situ doping. TiOSO(4) and NH(3)·H(2)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(2) were strengthened in IS-RPB, which was beneficial to the continuous production of high quality nano-TiO(2). Pure TiO(2) and iron-doped nano-TiO(2) (Fe-TiO(2)) 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(2) 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(3+) did not change the crystalline structure of TiO(2). Iron was highly dispersed in TiO(2) 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(2) to visible light was broadened from 3.06 eV to 2.26 eV. The degradation efficiency of gaseous toluene by Fe-TiO(2) under ultraviolet light was higher than that of pure TiO(2) and commercial P25 due to Fe(3+) effectively suppressing the recombination of TiO(2) electrons and holes; the highest efficiency produced by 1.0% Fe-TiO(2) was 95.7%.