Mechanism study on TiO2 inducing O2- and OH radicals in O3/H2O2 system for high-efficiency NO oxidation

Fanyu Meng; Lina Guo; Haocheng Zou; Boming Zhu; Fayang Zhou; Yiqing Zeng; Jiayou Han; Jun Yang; Shule Zhang; Qin Zhong

doi:10.1016/j.jhazmat.2020.123033

Mechanism study on TiO₂ inducing O₂^- and OH radicals in O₃/H₂O₂ system for high-efficiency NO oxidation

J Hazard Mater. 2020 Nov 15:399:123033. doi: 10.1016/j.jhazmat.2020.123033. Epub 2020 May 30.

Authors

Fanyu Meng¹, Lina Guo², Haocheng Zou¹, Boming Zhu¹, Fayang Zhou¹, Yiqing Zeng¹, Jiayou Han³, Jun Yang³, Shule Zhang⁴, Qin Zhong⁵

Affiliations

¹ School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, PR China.
² School of Civil Engineering and Architecture, Anhui University of Technology, Maanshan, Anhui, 243000, PR China.
³ Shanghai Meishan Steel Corporation Ltd., Nanjing, 210039, PR China.
⁴ School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, PR China. Electronic address: shulezhang@163.com.
⁵ School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, PR China. Electronic address: zq304@njust.edu.cn.

PMID: 32544767
DOI: 10.1016/j.jhazmat.2020.123033

Abstract

To achieve high NO oxidation efficiency, excessive O₃ must be used, which would lead to the high cost and escape of ozone. Herein, we adopted low cost and environmental-friendly TiO₂ as the catalyst of low concentration O₃ and H₂O₂ system for high-efficiency NO_x oxidation. The Ti sites on TiO₂ were the deprotonation sites of H₂O₂ and H₂O into Ti-OOH and Ti-OH species, respectively. We found that the surface of rutile phase TiO₂ had a low concentration Ti-OOH component but a large amount of Ti-OH after contacting with H₂O₂ solution, thus lots of ·OH and a few O₂^- radicals formed with introducing O₃ molecules. H₂O₂ solution induced the formation of a large amount of Ti-OOH and Ti-OH species on the anatase phase TiO₂ surface, thus lots of O₂^- generated in the O₃/H₂O₂ system. O₂^- and OH radicals could efficiently oxidize NO, in which O₂^- radicals could oxidize NO to NO₃^- in one step with high selectively. Therefore, anatase TiO₂ had better performance in NO_x oxidation than rutile phase TiO₂. The effect of temperature and SO₂ concentration on NO oxidation was also investigated, the results showed that TiO₂-A/O₃/H₂O₂ system promoted NO oxidation at a low temperature and a low concentration of SO₂.

Keywords: ()O(2)-and O()H radicals; Anatase and rutile phase TiO(2); NO oxidation mechanism; O(3)/H(2)O(2) system; Ti-OOH.