title: Natural Organic Matter Exposed to Sulfate Radicals Increases Its Potential to Form Halogenated Disinfection Byproducts.
abstract: Sulfate radical-based advanced oxidation processes (SR-AOPs) are considered as viable technologies to degrade a variety of recalcitrant organic pollutants. This study demonstrates that o-phthalic acid (PA) could lead to the formation of brominated disinfection byproducts (DBPs) in SR-AOPs in the presence of bromide. However, PA does not generate DBPs in conventional halogenation processes. We found that this was attributed to the formation of phenolic intermediates susceptible to halogenation, such as salicylic acid through the oxidation of PA by SO4(•-). In addition, reactive bromine species could be generated from Br(-) oxidation by SO4(•-). Similar in situ generation of phenolic functionalities likely occurred by converting carboxylic substituents on aromatics to hydroxyl when natural organic matter (NOM) was exposed to trace level SO4(•-). It was found that such structural reconfiguration led to a great increase in the reactivity of NOM toward free halogen and, thus, its DBP formation potential. After a surface water sample was treated with 0.1 μM persulfate for 48 h, its potential to form chloroform, trichloroacetic acid, and dichloroacetic acid increased from 197.8, 54.3, and 27.6 to 236.2, 86.6, and 57.6 μg/L, respectively. This is the first report on possible NOM reconfiguration upon exposure to low-level SO4(•-) that has an implication in DBP formation. The findings highlight potential risks associated with SO4(•-)-based oxidation processes and help to avoid such risks in design and operation.
authors.affiliation: Department of Environmental Science and Engineering, Nanjing Agricultural University , Nanjing 210095, China.
authors.forename: Junhe
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Environmental Science and Engineering, Nanjing Agricultural University , Nanjing 210095, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Dong
authors.affiliation: Department of Environmental Science and Engineering, Nanjing Agricultural University , Nanjing 210095, China.
authors.forename: Yuefei
authors.initials: Y
authors.lastname: Ji
authors.affiliation: Nanjing Institute of Environmental Science, Ministry of Environmental Protection of PRC , Nanjing 210042, China.
authors.forename: Deyang
authors.initials: D
authors.lastname: Kong
authors.affiliation: Department of Crop and Soil Sciences, University of Georgia , Griffin, Georgia 30223, United States.
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Huang
mesh_terms: D001965:Bromides / Q000737:chemistry; D001966:Bromine; D004203:Disinfection; D054879:Halogenation; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D001965:Bromides; D014874:Water Pollutants, Chemical; D001966:Bromine