title: Kinetics of ozonation of typical sulfonamides in water.
abstract: OBJECTIVE
  To investigate the kinetic rate constants ozone and hydroxyl radicals towards two groups of antimicrobials -sulfadiazine (SD) and sulfamethoxazole (SMX).
  
  
  METHODS
  The solute consumption method was used to detect the rate constants of ozone alone with sulfadiazine and sulfamethoxazole, and tertiary butanol was selected as a scavenging agent and pH was adjusted to 2.5 by adding orthophosphate buffers (OB); and the competition kinetics studying methodwith nitrobenzene as a reference was applied to measure the rate constants of hydroxyl radicals towards sulfadiazine and sulfamethoxazole, and pH was adjusted to 7.0 by adding OB.
  
  
  RESULTS
  The rate constants of SD and SMX with ozone alone were 261 mol(-1) · dm(3) · s(-1) and 303 mol(-1) · dm3 · s(-1) by calculating in low reaction system. The rate constants of hydroxyl radicals with SD and SMX were 2.2×1010 mol(-1) · dm(3) · s(-1) and 2.7×1010 mol(-1) · dm(3) · s(-1), respectively. Moreover, the rate constants of hydroxyl radicals with SMX were found to have increased from 3.6×109 mol(-1) · dm(3) · s(-1) to 2.8×1010 mol(-1) · dm(3) · s(-1) with pH value rising from 5.0 to 7.8.
  
  
  CONCLUSIONS
  SMX and SD are both refractory to ozone oxidation alone, and are liable to be degraded by hydroxyl radicals, and the rate constants of SMX with the hydroxyl radical slightly increases with pH rise.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, China. suiminghao.sui@gmail.com
authors.forename: MingHao
authors.initials: M
authors.lastname: Sui
authors.forename: Sichu
authors.initials: S
authors.lastname: Xing
authors.forename: ChunYan
authors.initials: C
authors.lastname: Zhu
authors.forename: Li
authors.initials: L
authors.lastname: Sheng
authors.forename: KeXiang
authors.initials: K
authors.lastname: Lu
authors.forename: NaiYun
authors.initials: N
authors.lastname: Gao
mesh_terms: D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D010126:Ozone / Q000737:chemistry*; D013420:Sulfamethoxazole / Q000737:chemistry; D013449:Sulfonamides / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D013449:Sulfonamides; D014867:Water; D017665:Hydroxyl Radical; D010126:Ozone; D013420:Sulfamethoxazole