Correspondence/Rebuttal pubs.acs.org/est
Response to Comment on “Airborne Trifluoroacetic Acid and Its Fraction from the Degradation of HFC-134a in Beijing, China″
W
e thank Dr. Wallington and his esteemed coauthors1 for taking an interest in this manuscript in which we estimated that, in Beijing, the fraction of airborne trifluoroacetic acid (TFA) coming from the degradation of HFC-134a was only 14% (6−33%).2 This was a surprising finding that is strengthened by the overall conservative approach that we used. Specifically, for the molar yield of TFA from HFC-134a we adopted the high end (0.36) of the range (0.29−0.36) that Kanakidou et al. presented in their 3-dimensional tropospheric study.3 Wallington and colleagues have correctly pointed out that, based on some of their own follow-up experimental work in smog chambers, the actual molar yield of TFA from HFC134a may be significantly lower; owing to C−C scission of the CF3CFHO radical when it is formed from exothermic reaction of NO with the corresponding peroxy radical, CF3CFHO2.4 Therefore, we accept that the true fraction of TFA from HFC-134a is closer to the low end of our estimated range. We furthermore agree that the comment from Wallington et al.1 strengthens one of the main conclusions and suggestions of our paper, that sources of TFA, other than HFC-134a oxidation, are present in the air over Beijing, and these need to be identified.
(3) Kanakidou, M.; Dentener, F. J.; Crutzen, P. J. A global 3dimensional study of the fate of HCFCs and HFC-134a in the troposphere. J. Geophys. Res. 1995, 100, 18781−18801. (4) Wallington, T. J.; Hurley, M. D.; Fracheboud, J. M.; Orlando, J. J.; Tyndall, G. S.; Sehested, J.; Møgelberg, T. E.; Nielsen, O. J. Role of excited CF3CFHO radicals in the atmospheric chemistry of HFC134a. J. Phys. Chem. 1996, 100, 18116−18122.
Jing Wu†,‡ Jonathan W. Martin§ Zihan Zhai† Keding Lu† Li Li† Xuekun Fang† Hangbiao Jin§ Jianxin Hu† Jianbo Zhang*,† †
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State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China ‡ China Waterborne Transport Research Institute, Beijing, China § Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
AUTHOR INFORMATION
Corresponding Author
*Phone: 86-10-62753438; fax: 86-10-62760755; e-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Wallington, T. J., Orlando, J. J., Tyndall, G. S., Nielsen O. J. Comment on “airborne trifluoroacetic acid and its fraction from the degradation of HFC-134a in Beijing, China”. (2) Wu, J.; Martin, J. W.; Zhai, Z.; Lu, K.; Fang, X.; Jin, H. Airborne trifluoroacetic acid and its fraction from the degradation of HFC-134a in Beijing, China. Environ. Sci. Technol. 2014, 48, 3675−3681. © 2014 American Chemical Society
Published: July 24, 2014 9949
dx.doi.org/10.1021/es5032568 | Environ. Sci. Technol. 2014, 48, 9949−9949
