title: Kinetics and mechanism investigation on the destruction of oxytetracycline by UV-254nm activation of persulfate.
abstract: Oxytetracycline (OTC), an important broad-spectrum antibiotic, has been detected extensively in various environmental systems, which may have a detrimental impact on ecosystem and human health through the development of drug resistant bacteria and pathogens. In this study, the degradation of OTC was evaluated by UV-254nm activated persulfate (PS). The observed UV fluence based pseudo first-order rate constant (kobs) was found to be the highest at near neutral pH conditions (pH 5.5-8.5). Presence of various natural water constituents had different effects on OTC degradation, with a significant enhancement in the presence of bicarbonate or Cu(2+). Limited elimination of total organic carbon (TOC) and PS was observed during the mineralization of OTC. Transformation byproducts in the presence and absence of hydroxyl radical scavenging agent tert-butanol (t-BuOH) were identified using ultra-high definition accurate-mass quadrupole time-of-flight liquid chromatography/mass spectrometer (LC-QTOF/MS). Potential OTC degradation mechanism was subsequently proposed revealing four different reaction pathways by SO4(-) reaction including hydroxylation (+16Da), demethylation (-14Da), decarbonylation (-28Da) and dehydration (-18Da). This study suggests that UV-254nm/PS is a promising treatment technology for the control of water pollution caused by emerging contaminants such as OTC.
authors.affiliation: Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 611756, China; Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012, United States.
authors.forename: Yiqing
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012, United States.
authors.forename: Xuexiang
authors.initials: X
authors.lastname: He
authors.affiliation: Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 611756, China.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012, United States. Electronic address: dionysios.d.dionysiou@uc.edu.
authors.forename: Dionysios D
authors.initials: DD
authors.lastname: Dionysiou
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D007700:Kinetics; D010118:Oxytetracycline / Q000737:chemistry*; D017670:Sodium Compounds / Q000737:chemistry* / Q000528:radiation effects*; D013431:Sulfates / Q000737:chemistry* / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents; D017670:Sodium Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical; C024625:sodium persulfate; D010118:Oxytetracycline
keywords: Mechanism; Oxytetracycline; Persulfate; Sulfate radical; UV-254 nm