Modeling degradation kinetics of gemfibrozil and naproxen in the UV/chlorine system: Roles of reactive species and effects of water matrix.
Water Res
; 202: 117445, 2021 Sep 01.
Article
em En
| MEDLINE
| ID: mdl-34303168
ABSTRACT
The UV/chlorine system has been regarded as an efficient oxidation technology for the removal of aqueous micropollutants. However, the roles of the possible radical species for this system on the elimination under environmentally relevant conditions/real waters were still largely unknown. Herein, the specific roles of radical species in the UV/chlorine oxidation degradation of gemfibrozil and naproxen as representative micropollutants were quantified by a steady-state kinetic prediction model considering the effects of water matrices. Overall, the model predicted results are consistent with the experimental data well. â¢OH and reactive chlorine species (RCS, such as Clâ¢, ClOâ¢, and Cl2â¢-) contributions to gemfibrozil and naproxen degradation were water matrix specific. In pure water, both primary reactive species (i.e., â¢OH and Clâ¢) and secondary species ClO⢠dominated gemfibrozil and naproxen degradation, and their individual and the sum of the contributions to degradation rates reduced with pH increase of from 5 to 9. In the presence of Cl-, we found that Cl2â¢- and in particular ClO⢠were responsible for the enhanced degradation with increasing Cl- concentrations due to the considerable ClO⢠reactivity of gemfibrozil (1.93 × 109 M-1 s-1) and naproxen (9.24 × 109 M-1 s-1) and the rapid transformation of Cl2â¢- to ClOâ¢. The presence of HCO3- notably facilitated the degradation in the UV/chlorine process because of the generation of CO3â¢-. CO3â¢- showed high reactivity with gemfibrozil and naproxen corresponding to respective second-order reaction rate constants of 2.45 × 107 and 3.50 × 107 M-1 s-1. Dissolved organic matter induced obvious scavenging for â¢OH, Clâ¢, and ClO⢠and greatly retarded the degradation. The constructed model considering the effects of above water matrix has successfully predicted the oxidation degradation kinetics in real waters, and both â¢OH and CO3â¢- are the predominant reactive species in the degradation. This study is helpful for comprehensive understanding the roles of possible radical species in micropollutant removal by UV/chlorine oxidation under real water matrix.
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Texto completo:
1
Coleções:
01-internacional
Contexto em Saúde:
2_ODS3
Base de dados:
MEDLINE
Assunto principal:
Poluentes Químicos da Água
/
Purificação da Água
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Water Res
Ano de publicação:
2021
Tipo de documento:
Article