ISCO of persistent organic contaminants

In situ chemical oxidation (ISCO) is a technique used in the treatment of chemical contaminants, especially for compounds that have been difficult to treat by established methods such as hydrocarbons, organic solvents, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). ISCO involves the addition of a relatively high concentration of an oxidant into contaminated groundwater or surface soils. Activated persulfate is growing in popularity as a treatment option because of potentially low soil oxidant demands, stability in the subsurface in conjunction with the steady generation of hydroxyl radicals and sulfate radicals. Ideally, oxidation would result in the complete mineralization of organic contaminants to carbon dioxide and water, but recent research shows this may not always be the case. Partial oxidation of organic contaminants can result in the formation of potentially toxic byproducts. Some of these byproducts have increased mobility and hydrophilic character in comparison to parent compounds, which poses a risk to groundwater resources. To understand these processes, we identified new oxidation byproducts from the oxidation of 16 PAHs in heat activated persulfate batch reactions using liquid chromatography high resolution mass spectrometry (LC-HRMS). To prioritize these potentially toxic oxidation byproducts, we tested their reactivity with specific biomolecules (N-acetyl-L-cysteine, N-acetyl-L-lysine, glutathione, and histidine). Results show that oxidation mixtures have higher reactivity with some biomolecules in the aqueous phase in comparison to controls, providing evidence of potentially toxic byproduct formation.

1. van Buren, J.; Cuthbertson, A. A.; Ocasio, D.; Sedlak, D. L. Ubiquitous Production of Organosulfates during Treatment of Organic Contaminants with Sulfate Radicals. Environmental Science & Technology Letters 2021, 8, 7, 574–580
2. van Buren, J.; Prasse, C.; Marron, E.; Skeel, B.; Sedlak, D. L. Ring-Cleavage Products Produced During The Initial Phase Of Oxidative Treatment Of Alkyl-Substituted Aromatic Compounds. Environmental Science & Technology 2020, 54 (13), 8352-8361.
3. Prasse, C.; von Gunten, U.; Sedlak, D. L. Chlorination Of Phenols Revisited: Unexpected Formation of α,β-Unsaturated C₄-Dicarbonyl Ring Cleavage Products. Environmental Science & Technology 2020, 54 (2), 826-834.
4. Yang, X.; Duan, Y.; Wang, J.; Wang, H.; Liu, H.; Sedlak, D. L. Impact Of Peroxymonocarbonate On The Transformation Of Organic Contaminants During Hydrogen Peroxide In Situ Chemical Oxidation. Environmental Science & Technology Letters 2019, 6 (12), 781-786.
5. Bruton, T.; Sedlak, D. L. Treatment Of Perfluoroalkyl Acids By Heat-Activated Persulfate Under Conditions Representative Of In Situ Chemical Oxidation. Chemosphere 2018, 206, 457-464.
6. Prasse, C.; Ford, B.; Nomura, D.; Sedlak, D. L. Unexpected Transformation Of Dissolved Phenols To Toxic Dicarbonyls By Hydroxyl Radicals And UV Light. Proceedings of the National Academy of Sciences 2018, 115 (10), 2311-2316.
7. Bruton, T.; Sedlak, D. L. Treatment Of Aqueous Film-Forming Foam By Heat-Activated Persulfate Under Conditions Representative Of In Situ Chemical Oxidation. Environmental Science & Technology 2017, 51 (23), 13878-13885.
8. Liu, H.; Bruton, T.; Li, W.; Buren, J.; Prasse, C.; Doyle, F.; Sedlak, D. L. Oxidation Of Benzene By Persulfate In The Presence Of Fe(III)- And Mn(IV)-Containing Oxides: Stoichiometric Efficiency And Transformation Products. Environmental Science & Technology 2016, 50 (2), 890-898.