title: Transformation of 17alpha-ethinylestradiol during water chlorination: effects of bromide on kinetics, products, and transformation pathways.
abstract: Kinetics, products, and pathways of 17alpha-ethinylestradiol (EE2) transformation during chlorination of water with and without bromide (Br(-)) were studied to evaluate the effect of chlorination on the fate of steroid estrogens. Br(-) can be important for the fate of EE2 during chlorination because of a rapid conversion of Br(-) to bromine by chlorine and a approximately 1000 times higher reactivity of bromine than chlorine toward EE2. Experimental data and model calculations for EE2 chlorination show that 4-chloro EE2 and 2,4-dichloro EE2 are the major initial transformation products in absence of Br(-). With increasing concentration of Br(-), the bromo-analogous of the chloro EE2s becomes significant as additional initial transformation products. Those initial transformation products of EE2 are generally quickly further transformed to products with a destroyed phenolic moiety. Transformation of EE2 during chlorination becomes considerably faster at Br(-) concentrations higher than 0.25 microM (20 microg L(-1)). However, in presence of model dissolved organic matter such as glycine or phenol, the accelerating effect of Br(-) diminishes due to a more rapid consumption of bromine than chlorine by these compounds. A kinetic model was developed which allows to predict EE2 transformation during chlorination of natural waters and wastewaters in presence of Br(-) and low concentrations of ammonia (<10 microM). It could be demonstrated in these systems that bromine produced from Br(-) is mainly responsible for EE2 transformation.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600, Dübendorf, Switzerland.
authors.forename: Yunho
authors.initials: Y
authors.lastname: Lee
authors.forename: Urs
authors.initials: U
authors.lastname: von Gunten
mesh_terms: D001965:Bromides / Q000737:chemistry*; D001966:Bromine / Q000737:chemistry; D002713:Chlorine / Q000737:chemistry; D004997:Ethinyl Estradiol / Q000737:chemistry*; D005618:Fresh Water / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D054879:Halogenation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D009930:Organic Chemicals / Q000737:chemistry; D010636:Phenols / Q000737:chemistry; D012995:Solubility; D013557:Switzerland; D014865:Waste Disposal, Fluid; D014867:Water / Q000737:chemistry*
chemical_list: D001965:Bromides; D009930:Organic Chemicals; D010636:Phenols; D014867:Water; D004997:Ethinyl Estradiol; D002713:Chlorine; D001966:Bromine; D005998:Glycine