title: Effect of oxidation on nitro-based pharmaceutical degradation and trichloronitromethane formation.
abstract: Nitro-based compounds are the direct precursors of trichloronitromethane during chlorination disinfection. Two nitro-based pharmaceuticals ranitidine and nizatidine were selected as model compounds to assess the effect of oxidation on the removal of nitro-based pharmaceuticals, as well as the reduction of their trichloronitromethane formation potentials (TCNMFPs). The four oxidants were ozone (O3), chlorine (Cl2), chlorine dioxide (ClO2) and potassium permanganate (KMnO4). The changes in pharmaceuticals and their TCNMFPs during oxidation using various oxidants and dosages were quantified. The relationships between oxidation product structures and TCNMFP changes were also analyzed. The results showed that oxidation with Cl2 and KMnO4 were more effective than ClO2 and O3 in removing the nitro-based pharmaceuticals. Meanwhile, decreased TCNMFPs by KMnO4 oxidation but increased TCNMFPs by Cl2, ClO2 and O3 oxidation were observed. The results of product analysis indicated that chlorine transfer products had higher TCNMFPs, while oxygen transfer products made little contribution to TCNMFPs after oxidation. In addition, one possible reaction pathway leading TCNMFP increase was that chloro-nitromethane or nitromethane, which was a better TCNM precursor, formed when double bond was attacked by oxidants.
authors.affiliation: Department of Environmental Engineering, School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Environmental Engineering, School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China. Electronic address: zhoubeihai@sina.com.
authors.forename: Beihai
authors.initials: B
authors.lastname: Zhou
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Yang
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Xiaomao
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China; Civil and Environmental Engineering Programs, Pennsylvania State University, Middletown, PA 17057, USA.
authors.forename: Yuefeng
authors.initials: Y
authors.lastname: Xie
mesh_terms: D004202:Disinfectants / Q000737:chemistry; D004784:Environmental Monitoring; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D016567:Nizatidine / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D004364:Pharmaceutical Preparations / Q000737:chemistry; D011899:Ranitidine / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D004202:Disinfectants; D006843:Hydrocarbons, Chlorinated; D016877:Oxidants; D004364:Pharmaceutical Preparations; D014874:Water Pollutants, Chemical; D011899:Ranitidine; C100187:chloropicrin; D016567:Nizatidine
keywords: Chlorine; Chlorine dioxide; Nitro-based pharmaceutical; Ozone; Potassium permanganate; Trichloronitromethane