title: Comparison of iodinated trihalomethanes formation during aqueous chlor(am)ination of different iodinated X-ray contrast media compounds in the presence of natural organic matter.
abstract: Iodinated trihalomethanes (I-THMs) formation during chlorination and chloramination of five iodinated X-ray contrast media (ICM) compounds (iopamidol, iopromide, iodixanol, histodenz, and diatrizoate) in the presence of natural organic matter (NOM) was evaluated and compared. Chlorination and chloramination of ICM in the absence of NOM yielded only a trace amount of I-THMs, while levels of I-THMs were enhanced substantially in raw water samples. With the presence of NOM, the order with respect to the maximum yield of I-THMs observed during chlorination was iopamidol >> histodenz > iodixanol > diatrizoate > iopromide. During chloramination, I-THM formation was enhanced for hisodenz, iodixanol, diatrizoate, and iopromide. The order with respect to the maximum yield of I-THMs observed during chloramination was iopamidol > diatrizoate > iodixanol > histodenz > iopromide. With the exception of iopamidol, I-THM formation was favored at relatively low chlorine doses (≤100 μM) during ICM chlorination, and significant suppression was observed with high chlorine doses applied (＞100 μM). However, during chloramination, increasing monochloramine dose monotonously increased the yield of I-THMs for the five ICM. During chlorination of iodixanol, histodenz, and diatrizoate, the yields of I-THMs exhibited three distinct trends as the pH increased from 5 to 9, while peak I-THM formation was found at circumneutral pH for chloramination. Increasing bromide concentration not only considerably enhanced the yield of I-THMs but also shifted the I-THMs towards bromine-containing ones and increased the formation of higher bromine-incorporated species (e.g., CHBrClI and CHBr2I), especially in chloramination. These results are of particular interest to understand I-THM formation mechanisms during chlorination and chloramination of waters containing ICM.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. Electronic address: tjwenwu@gmail.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Tian-Yang
authors.initials: TY
authors.lastname: Zhang
authors.affiliation: College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090, PR China.
authors.forename: Chen-Yan
authors.initials: CY
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Lin
authors.initials: L
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Sheng-Ji
authors.initials: SJ
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Nai-Yun
authors.initials: NY
authors.lastname: Gao
mesh_terms: D001965:Bromides / Q000737:chemistry; D001966:Bromine / Q000737:chemistry*; D002681:China; D002700:Chloramines / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry*; D003287:Contrast Media / Q000737:chemistry*; D004202:Disinfectants / Q000737:chemistry; D004203:Disinfection / Q000379:methods; D054879:Halogenation; D006863:Hydrogen-Ion Concentration; D007455:Iodine / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D022882:Trihalomethanes / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*; D014881:Water Supply; D014965:X-Rays
chemical_list: D001965:Bromides; D002700:Chloramines; D003287:Contrast Media; D004202:Disinfectants; D009930:Organic Chemicals; D022882:Trihalomethanes; D014874:Water Pollutants, Chemical; D014867:Water; D002713:Chlorine; D007455:Iodine; C030816:chloramine; D001966:Bromine
keywords: Chlor(am)ination; Disinfection by-products; Iodinated X-ray contrast media; Iodinated trihalomethanes