title: Kinetics and mechanisms of formation of earthy and musty odor compounds: Chloroanisoles during water chlorination.
abstract: Chloroanisoles are often reported as off-flavor compounds which produce an earthy and musty flavors and odors in drinking water. To improve understanding and ultimately minimize the formation of 2,4-dichloroanisole (2,4-DCA), 2,6-dichloroanisole (2,6-DCA) and 2,4,6-trichloroanisole (2,4,6-TCA), which have low odor threshold concentrations (OTC: 0.03-4 ng L(-1)), a kinetic database for the chlorination of anisole was established by kinetic measurements. The results showed that HOCl reacted with anisole in acidic solution, with the hydrogen ion as an important catalyst. Quantification of product distribution of the produced chloroanisoles demonstrated that a chlorine attack in the para-position was favored over the ortho-position. A kinetic model was formulated, which permitted investigation of the relative importance of the chlorine dose and other water quality parameters including the concentrations of anisole and several metal ions, as well as temperature, on the product distribution of chloroanisoles. In general, high chlorine doses led to low concentrations of intermediates. The presence of ions such as Fe(3+) and Al(3+) facilitated the formation of chloroanisoles, but Zn(2+) and Mn(2+) did not. The kinetic model can be applied to optimize water chlorination and minimize earthy and musty odors.
authors: College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
authors: Kejia
authors: K
authors: Zhang
authors: College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
authors: Xinyan
authors: X
authors: Zhou
authors: College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
authors: Tuqiao
authors: T
authors: Zhang
authors: College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, Zhejiang, China; Urban Administration Bureau of West Lake District, Hangzhou, 310000, Zhejiang, China.
authors: Minmin
authors: M
authors: Mao
authors: State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092, China. Electronic address: lilei87296281@126.com.
authors: Lei
authors: L
authors: Li
authors: School of Environmental Science and Engineering, Xiamen University of Technology, Xiamen, 361024, Fujian, China.
authors: Wenchao
authors: W
authors: Liao
mesh_terms: D000840:Anisoles / Q000737:chemistry*; D054879:Halogenation; D006997:Hypochlorous Acid / Q000737:chemistry*; D007700:Kinetics; D008670:Metals / Q000737:chemistry; D008956:Models, Chemical; D009812:Odorants; D013649:Taste; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D000840:Anisoles; D008670:Metals; D014874:Water Pollutants, Chemical; D006997:Hypochlorous Acid
keywords: Chlorination; Chloroanisole; Earthy and musty odor; Kinetic model