title: Trihalomethane hydrolysis in drinking water at elevated temperatures.
abstract: Hydrolysis could contribute to the loss of trihalomethanes (THMs) in the drinking water at elevated temperatures. This study was aimed at investigating THM hydrolysis pertaining to the storage of hot boiled water in enclosed containers. The water pH value was in the range of 6.1-8.2 and the water temperature was varied from 65 to 95 °C. The effects of halide ions, natural organic matter, and drinking water matrix were investigated. Results showed that the hydrolysis rates declined in the order following CHBrCl2 > CHBr2Cl > CHBr3 > CHCl3. THM hydrolysis was primarily through the alkaline pathway, except for CHCl3 in water at relatively low pH value. The activation energies for the alkaline hydrolysis of CHCl3, CHBrCl2, CHBr2Cl and CHBr3 were 109, 113, 115 and 116 kJ/mol, respectively. No hydrolysis intermediates could accumulate in the water. The natural organic matter, and probably other constituents, in drinking water could substantially decrease THM hydrolysis rates by more than 50%. When a drinking water was at 90 °C or above, the first order rate constants for THM hydrolysis were in the magnitude of 10(-2)‒10(-1) 1/h. When the boiled real tap water was stored in an enclosed container, THMs continued increasing during the first few hours and then kept decreasing later on due to the competition between hydrolysis and further formation. The removal of THMs, especially brominated THMs, by hydrolysis would greatly reduce one's exposure to disinfection by-products by consuming the boiled water stored in enclosed containers.
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Xiao-Lu
authors.initials: XL
authors.lastname: Zhang
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Yang
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: wangxiaomao@tsinghua.edu.cn.
authors.forename: Xiao-Mao
authors.initials: XM
authors.lastname: Wang
authors.affiliation: Department of Environmental Engineering and Earth Sciences, Clemson University, 342 Computer Court, Anderson, SC 29625, USA.
authors.forename: Tanju
authors.initials: T
authors.lastname: Karanfil
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.
authors.forename: Yuefeng F
authors.initials: YF
authors.lastname: Xie
mesh_terms: D004203:Disinfection / Q000379:methods; D060766:Drinking Water / Q000737:chemistry*; D054879:Halogenation; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009930:Organic Chemicals / Q000737:chemistry; D022882:Trihalomethanes / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D060766:Drinking Water; D009930:Organic Chemicals; D022882:Trihalomethanes; D014874:Water Pollutants, Chemical
keywords: Boiling; Disinfection by-products (DBPs); Hydrolysis; Kinetics; Trihalomethanes (THMs)