Significant influences of TiO2 crystal structures on NO2 and HONO emissions from the nitrates photolysis

Wenwen Xu; Wangjin Yang; Chong Han; He Yang; Xiangxin Xue

doi:10.1016/j.jes.2020.09.016

Significant influences of TiO₂ crystal structures on NO₂ and HONO emissions from the nitrates photolysis

J Environ Sci (China). 2021 Apr:102:198-206. doi: 10.1016/j.jes.2020.09.016. Epub 2020 Oct 3.

Authors

Wenwen Xu¹, Wangjin Yang¹, Chong Han², He Yang¹, Xiangxin Xue¹

Affiliations

¹ School of Metallurgy, Northeastern University, Shenyang 110819, China.
² School of Metallurgy, Northeastern University, Shenyang 110819, China. Electronic address: hanch@smm.neu.edu.cn.

PMID: 33637244
DOI: 10.1016/j.jes.2020.09.016

Abstract

The emissions of NO₂ and HONO from the KNO₃ photolysis in the presence of TiO₂ were measured using a round-shape reactor coupled to a NO_x analyzer. TiO₂ played important roles in the emission flux density of NO₂ (R_NO₂) and HONO (R_HONO), depending on crystal structures and mass ratios of TiO₂. R_NO₂ and R_HONO significantly decreased with increasing the rutile and anatase mass ratios from 0 to 8 and 0.5 wt.%, respectively. Nevertheless, with further increasing the anatase mass ratio to 8 wt.%, there was an increase in R_NO₂ and R_HONO. R_NO₂ on KNO₃/TiO₂/SiO₂ had positive correlation with the KNO₃ mass (1-20 wt.%), irradiation intensity (80-400 W/m²) and temperature (278-308 K), while it had the maximum value at the relative humidity (RH) of 55%. R_HONO on KNO₃/TiO₂/SiO₂ slightly varied with the KNO₃ mass and temperature, whereas it increased with the irradiation intensity and RH. In addition, the mechanism for NO₂ and HONO emissions from the nitrates photolysis and atmospheric implications were discussed.

Keywords: NO(2); Nitrates; Photolysis; TiO(2).

MeSH terms

Nitrates*
Nitrogen Dioxide*
Nitrous Acid
Photolysis
Silicon Dioxide
Titanium

Substances

Nitrates
titanium dioxide
Silicon Dioxide
Titanium
Nitrogen Dioxide
Nitrous Acid