title: A New Reaction Pathway for Bromite to Bromate in the Ozonation of Bromide.
abstract: Ozone is often used in the treatment of drinking water. This may cause problems if the water to be treated contains bromide as its reaction with ozone leads to the formation of bromate, which is considered to be carcinogenic. Bromate formation is a multistep process resulting from the reaction of ozone with bromite. Although this process seemed to be established, it has been shown that ozone reacts with bromite not by the previously assumed mechanism via O transfer but via electron transfer. Besides bromate, the electron-transfer reaction also yields O3(•-), the precursor of OH radicals. The experiments were set up in such a way that OH radicals are not produced from ozone self-decomposition but solely by the electron-transfer reaction. This study shows that hydroxyl radicals are indeed generated by using tBuOH as the OH radical scavenger and measuring its product, formaldehyde. HOBr and bromate yields were measured in systems with and without tBuOH. As OH radicals contribute to bromate formation, higher bromate and HOBr yields were observed in the absence of tBuOH than in its presence, where all OH radicals are scavenged. On the basis of the results presented here, a pathway from bromide to bromate, revised in the last step, was suggested.
authors.affiliation: Instrumental Analytical Chemistry, University of Duisburg-Essen , Universitätsstraße 5, 45141 Essen, Germany.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Fischbacher
authors.affiliation: Instrumental Analytical Chemistry, University of Duisburg-Essen , Universitätsstraße 5, 45141 Essen, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Löppenberg
authors.affiliation: Instrumental Analytical Chemistry, University of Duisburg-Essen , Universitätsstraße 5, 45141 Essen, Germany.|Max-Planck-Institut für Bioanorganische Chemie , Stiftstr. 34-36, 45413 Mülheim an der Ruhr, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: von Sonntag
authors.affiliation: Instrumental Analytical Chemistry, University of Duisburg-Essen , Universitätsstraße 5, 45141 Essen, Germany.|Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen , Universitätsstraße 2, 45141 Essen, Germany.
authors.forename: Torsten C
authors.initials: TC
authors.lastname: Schmidt
mesh_terms: D001959:Bromates / Q000737:chemistry*; D001965:Bromides / Q000737:chemistry*; D005557:Formaldehyde / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D000432:Methanol / Q000737:chemistry; D010126:Ozone / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry
chemical_list: D001959:Bromates; D001965:Bromides; D010636:Phenols; D005557:Formaldehyde; D017665:Hydroxyl Radical; D010126:Ozone; C032038:2-bromophenol; C027664:hypobromous acid; C032037:4-bromophenol; D000432:Methanol