Degradation of metronidazole by UV/chlorine treatment: Efficiency, mechanism, pathways and DBPs formation
| Autor: | Jun Shi, Kun Fu, Xuchun Li, Huiping Deng, Yishuai Pan |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Environmental Engineering
Halogenation Ultraviolet Rays Health Toxicology and Mutagenesis Radical 0208 environmental biotechnology Kinetics chemistry.chemical_element 02 engineering and technology 010501 environmental sciences 01 natural sciences Water Purification Reaction rate constant Metronidazole Chlorine Environmental Chemistry Scavenging 0105 earth and related environmental sciences Chemistry Public Health Environmental and Occupational Health General Medicine General Chemistry Models Theoretical Pollution 020801 environmental engineering Disinfection Ultrapure water Degradation (geology) Water treatment Oxidation-Reduction Water Pollutants Chemical Nuclear chemistry |
| Zdroj: | Chemosphere. 224 |
| ISSN: | 1879-1298 |
| Popis: | Metronidazole (MET) is a widely used antibiotic but is recalcitrant in aquatic environment. This study investigated elimination of MET by UV/chlorine process systematically. The degradation of MET in the process well fitted pseudo first-order kinetics. Decreasing pH from 9 to 5 raised the rate constant from 0.0199 min−1 to 0.1485 min−1, possibly ascribed to change in species distribution and apparent quantum yields of radicals. Scavenging experiments indicated that both HO and Cl contributed to the degradation of MET, and that HO was the dominant species in the pH range studied. The second-order rate constant between Cl and MET was determined to be (5.64 ± 0.1) × 109 M−1 s−1. Three products were identified by UPLC-Q-TOF MS and degradation pathway was thus proposed. Significant amounts of chlorinated disinfection by-products (DBPs) were produced and 1,1,1-TCP was the dominant (83.6%–92.3%) in the UV/chlorine process. The kinetic model developed fitted well with experimental results, and was used to examine the effects of typical water parameters, such as chorine dosage, pH, inorganic anions, NOM and real water matrix. Furthermore, removal efficiency of MET by the UV/chlorine process were assessed in terms of electrical energy per order (EE/O). The efficiency was about 0.43 kWh m−3 order−1, 0.54 kWh m−3 order−1, 0.57 kWh m−3 order−1, respectively, for the removal of MET in ultrapure water (UPW) and two types of real water samples, indicating that UV/chorine was a practical method for authentic drinking water treatment practices. |
| Databáze: | OpenAIRE |
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