Preparation of TiO2 and Fe-TiO2 with an Impinging Stream-Rotating Packed Bed by the Precipitation Method for the Photodegradation of Gaseous Toluene

Guangping Zeng; Qiaoling Zhang; Youzhi Liu; Shaochuang Zhang; Jing Guo

doi:10.3390/nano9081173

Preparation of TiO₂ and Fe-TiO₂ with an Impinging Stream-Rotating Packed Bed by the Precipitation Method for the Photodegradation of Gaseous Toluene

Nanomaterials (Basel). 2019 Aug 16;9(8):1173. doi: 10.3390/nano9081173.

Authors

Guangping Zeng¹, Qiaoling Zhang², Youzhi Liu¹, Shaochuang Zhang¹, Jing Guo¹

Affiliations

¹ Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan 030051, China.
² Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan 030051, China. zhangqiaoling@nuc.edu.cn.

Abstract

Nano-TiO₂ 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-TiO₂ with high dispersion, a small particle size and high photocatalytic activity. In this paper, nano-TiO₂ 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 Fe³⁺ in-situ doping. TiOSO₄ and NH₃·H₂O 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-TiO₂ were strengthened in IS-RPB, which was beneficial to the continuous production of high quality nano-TiO₂. Pure TiO₂ and iron-doped nano-TiO₂ (Fe-TiO₂) 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 TiO₂ 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 Fe³⁺ did not change the crystalline structure of TiO₂. Iron was highly dispersed in TiO₂ 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 TiO₂ to visible light was broadened from 3.06 eV to 2.26 eV. The degradation efficiency of gaseous toluene by Fe-TiO₂ under ultraviolet light was higher than that of pure TiO₂ and commercial P25 due to Fe³⁺ effectively suppressing the recombination of TiO₂ electrons and holes; the highest efficiency produced by 1.0% Fe-TiO₂ was 95.7%.

Keywords: doping; high-gravity technique; impinging stream-rotating packed bed; nano titanium dioxide; photocatalysis; photocatalytic activity; precipitation method.