Formation of Brominated Disinfection Byproducts during Chloramination of Drinking Water: New Polar Species and Overall Kinetics

• Published in: Environmental science & technology 2014-03, Vol.48 (5), p.2579-2588
• Main Authors: Zhai, Hongyan, Zhang, Xiangru, Zhu, Xiaohu, Liu, Jiaqi, Ji, Min
• Format: Article
• Language: English
• Subjects: Applied sciences; By products; Chloramines - chemistry; Chromatography; Chromatography, High Pressure Liquid; Disinfection & disinfectants; Disinfection - methods; Drinking water; Drinking Water - chemistry; Drinking Water - standards; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; Halogenation; Hydrocarbons, Brominated - analysis; Hydrocarbons, Brominated - chemistry; Mass spectrometry; Models, Chemical; Pollution; Simulation; Spectrometry, Mass, Electrospray Ionization; Water Pollutants, Chemical - analysis; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es4034765

The formation of brominated disinfection byproducts (Br-DBPs), which are generally significantly more cytotoxic and genotoxic than their chlorinated analogues, in chloramination has not been fully examined. In this work, the formation of new polar Br-DBPs in simulated drinking waters was examined using state-of-the-art ultraperformance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry. As many as 29 aliphatic, aromatic, or nitrogenous polar Br-DBPs were detected in chloramination, and five of them (including 2,4,6-tribromoresorcinol, 2,6-dibromo-4-nitrophenol, 2,2,4-tribromo-5-hydroxy-4-cyclopentene-1,3-dione, 2,2,4-dibromochloro-5-hydroxy-4-cyclopentene-1,3-dione, and 2,2,4-bromodichloro-5-hydroxy-4-cyclopentene-1,3-dione) were tentatively identified. Unlike chlorination, chloramination favored the formation of aromatic and nitrogenous polar Br-DBPs and was mild enough to allow polar intermediate Br-DBPs to accumulate. To further explore the formation mechanism of Br-DBPs in chloramination, a quantitative empirical model involving 33 major reactions was developed to describe the overall kinetics. According to the modeling results, bromochloramine and monobromamine were the major species responsible for 54.2–58.1% and 41.7–45.7%, respectively, of the formed Br-DBPs, while hypobromous acid accounted for only 0.2% of the formed Br-DBPs; direct reactions between monochloramine and natural organic matter accounted for the majority of the formed chlorinated DBPs (93.7–95.1%); hypochlorous acid and hypobromous acid in the chloramination were at ng/L or subng/L levels, which were not enough to cause polar intermediate Br-DBPs to decompose.