Inhibition Behavior of PCDD/Fs Congeners by Addition of N-containing Compound in the Iron Ore Sintering

doi:10.4209/aaqr.2019.12.0660

Inhibition Behavior of PCDD/Fs Congeners by Addition of N-containing Compound in the Iron Ore Sintering

Yifan Wang¹, Lixin Qian¹, Zhengwei Yu This email address is being protected from spambots. You need JavaScript enabled to view it.¹, Tiejun Chun This email address is being protected from spambots. You need JavaScript enabled to view it.¹, Hongming Long^1,2, Xuejian Wu¹, Jiaxin Li¹

¹ School of Metallurgical Engineering, Anhui University of Technology, Ma’anshan, Anhui 243002, China
² Anhui Province Key Laboratory of Metallurgy Engineering & Resources Recycling, Anhui University of Technology, Ma’anshan 243002, China

Received: February 3, 2020
Revised: May 13, 2020
Accepted: May 15, 2020
Download Citation: ||https://doi.org/10.4209/aaqr.2019.12.0660

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Cite this article:

Wang, Y., Qian, L., Yu, Z., Chun, T., Long, H., Wu, X. and Li, J. (2020) Inhibition Behavior of PCDD/Fs Congeners by Addition of N-containing Compound in the Iron Ore Sintering. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.2019.12.0660

HIGHLIGHTS

Urea can inhibit the emission of total PCDD/Fs.
Urea promotes the formation of TeCDF and TeCDD in the iron ore sintering.
The NH₂× and H× can be formed in the pyrolysis process of urea.
The C-O bond of PCDD/Fs molecules can be attacked and broken by the H×.
The H× attacked the C-Cl bonds to promotes the hydrodechlorination reaction.

ABSTRACT

PCDD/Fs are typical toxic persistent aromatic compounds with great harm to the air quality and human health. In this study, the suppression effects of urea on total PCDD/Fs and their congeners emission were investigated via the sintering pot tests, and the inhibition mechanisms were studied. The results showed that the I-TEQ values of total PCDD/Fs decreased from 0.50 (non-urea) to 0.20, 0.12 and 0.20 ng I-TEQ Nm^-3 with the addition of 0.02, 0.035 and 0.05 wt.% urea solid particles into the iron ore sintering mixture. However, the use of urea increased the low-chlorinated values from 0.003 to 0.009, 0.006 and 0.006 ng I-TEQ Nm^-3, and from 0.014 to 0.020, 0.018 and 0.020 ng I-TEQ Nm^-3, respectively for TeCDF and TeCDD. Moreover, the average I-TEQ number of chlorine substituents of PCDFs and PCDDs also decreased after adding urea, indicating that urea can inhibit the chlorination process of PCDD/Fs or promote the dechlorination reaction. The possible suppression mechanism and the high-chlorinated PCDD/Fs hydrodechlorination mechanism by urea were proposed and discussed.

Keywords: PCDD/Fs; Congeners; Urea; Active radical; Iron ore sintering.