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Halogen Radicals Contribute to the Halogenation and Degradation of Chemical Additives Used in Hydraulic Fracturing

  • Moshan Chen
    Moshan Chen
    Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
    More by Moshan Chen
  • Carter A. Rholl
    Carter A. Rholl
    Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
  • Tianchen He
    Tianchen He
    Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
    More by Tianchen He
  • Aditi Sharma
    Aditi Sharma
    Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
    More by Aditi Sharma
  • , and 
  • Kimberly M. Parker*
    Kimberly M. Parker
    Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
    *Email: [email protected]. Phone: (314) 935-3461. Fax: (314) 935-7211.
Cite this: Environ. Sci. Technol. 2021, 55, 3, 1545–1554
Publication Date (Web):January 15, 2021
https://doi.org/10.1021/acs.est.0c03685
Copyright © 2021 American Chemical Society
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Abstract

In hydraulic fracturing fluids, the oxidant persulfate is used to generate sulfate radical to break down polymer-based gels. However, sulfate radical may be scavenged by high concentrations of halides in hydraulic fracturing fluids, producing halogen radicals (e.g., Cl, Cl2•–, Br, Br2•–, and BrCl•–). In this study, we investigated how halogen radicals alter the mechanisms and kinetics of the degradation of organic chemicals in hydraulic fracturing fluids. Using a radical scavenger (i.e., isopropanol), we determined that halogenated products of additives such as cinnamaldehyde (i.e., α-chlorocinnamaldehyde and α-bromocinnamaldehyde) and citrate (i.e., trihalomethanes) were generated via a pathway involving halogen radicals. We next investigated the impact of halogen radicals on cinnamaldehyde degradation rates. The conversion of sulfate radicals to halogen radicals may result in selective degradation of organic compounds. Surprisingly, we found that the addition of halides to convert sulfate radicals to halogen radicals did not result in selective degradation of cinnamaldehyde over other compounds (i.e., benzoate and guar), which may challenge the application of radical selectivity experiments to more complex molecules. Overall, we find that halogen radicals, known to react in advanced oxidative treatment and sunlight photochemistry, also contribute to the unintended degradation and halogenation of additives in hydraulic fracturing fluids.

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  • Supplemental experimental procedures and analytical methods, results and analysis including oxidant measurements, additional cinnamaldehyde degradation experiments, and kinetic calculations (PDF)

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Cited By


This article is cited by 2 publications.

  1. Shuangshuang Cheng, Yujie Zhao, Yanheng Pan, Jinpeng Yu, Yu Lei, Xin Lei, Gangfeng Ouyang, Xin Yang. Role of Antioxidant Moieties in the Quenching of a Purine Radical by Dissolved Organic Matter. Environmental Science & Technology 2021, Article ASAP.
  2. Christopher B Hill, Om P. Yadav, Eakalak Khan. Examining hydraulic fracturing chemicals: A temporal and comparative analysis. Water Research 2022, 208 , 117878. https://doi.org/10.1016/j.watres.2021.117878