Fe3+ and Ce3+ modified nano-TiO2 for degradation of exhaust gas in tunnels

Yin Luo,Zhong Qin,Hengcong Zhang,Jianmin Wu

doi:10.1515/gps-2021-0063

Abstract

Abstract To solve the environmental pollution caused by automobile exhaust in a tunnel, this study has developed a modified nano-TiO2 based on Fe3+ and Ce3+. The modified nano-TiO2 is prepared by the sol–gel method, and the modification adopts Fe3+ single-doping, Ce3+ sing-doping, and co-doping. The properties were also characterized by X-ray diffraction analysis, UV-vis diffuse reflectance analysis, fluorescence spectroscopy analysis, specific surface area analysis, and paramagnetic resonance popper analysis. The analyses showed that the doping of ions would change the energy band structure of nano-TiO2 and produce crystal defects, thus improving the photocatalytic activity. Then, a self-fabricated exhaust gas degradation device was used to carry out the exhaust gas degradation experiments. The results showed that the modification improves the catalytic efficiency of nano-TiO2, and Fe3+, Ce3+ co-doping > Ce3+ single-doping > Fe3+ single-doping > pure TiO2. At the dosage of 0.5%, the maximum degradation efficiencies of NO and CO before compensation are 53.85% and 16.39%, respectively, and the maximum degradation rates are 1.04 and 0.93 ppm·min−1. After compensation, the maximum degradation efficiencies of NO and CO are 20.14% and 6.04%, respectively. The maximum degradation rate is 0.40 and 0.41 ppm·min−1, respectively.

Highlights

In 2017, the number of motor vehicles in China had reached 310 million, and the total emission of motor vehicle exhaust pollutants reached 43,597,000 tons
The nano-TiO2 and modified nano-TiO2 were prepared by the sol–gel method [14,15,16,17,28]
The determination of X-ray diffraction (XRD) crystal size is related to the peak width of the diffraction peak and the material grain size, which is calculated in Eq 9: increase the diffusion energy barrier of atoms between grains and prevent direct contact between grains

Summary

Introduction

In 2017, the number of motor vehicles in China had reached 310 million, and the total emission of motor vehicle exhaust pollutants reached 43,597,000 tons. The substantial exhaust emissions will threaten human beings’ living environment if not treated in time. The automobile exhaust mainly includes CO, HC, NOx, CO2, and CO and binds to hemoglobin which will cause human hypoxia. HC and NOx can form toxic fumes through the action of ultraviolet light, and can cause discomforts, such as dizziness, chest tightness [1], and even cancer [2,3,4]. Nano-TiO2 has the following advantages [5,6,7]: (i) low price, simple preparation equipment, and nontoxic; (ii) strong photocatalytic performance and strong redox ability; (iii) excellent chemical stability and corrosion resistance; (iv) suitable forbidden bandwidth (3.2 eV) and can effectively absorb ultraviolet light with wavelengths less than 387 nm in sunlight, etc. Compared with other catalysts, nano-TiO2 has obvious advantages that make it the most widely used

Methods

Results

Conclusion