Direct and indirect photolysis of the antibiotic enoxacin: kinetics of oxidation by reactive photo-induced species and simulations

Author(s)

Lastre-Acosta, Arlen Mabel ^[1] ; Barberato, Bruna ^[1] ; Silva Parizi, Marcela Prado ^[2] ; Silva Costa Teixeira, Antonio Carlos ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Chem Engn, Chem Syst Engn Ctr, Res Grp Adv Oxidat Proc AdOx, Av Prof Luciano Gualberto, Tr 3, BR-380 Sao Paulo, SP - Brazil

^[2] Sao Paulo State Univ UNESP, Dept Energy Engn, Av Barrageiros, BR-1881 Rosana, SP - Brazil

• Document type: Journal article
• Source: Environmental Science and Pollution Research; v. 26, n. 5, p. 4337-4347, FEB 2019.
• Web of Science Citations: 3

Abstract

The purpose of this study was to investigate the aqueous phase photochemical behavior of enoxacin (ENO), an antibiotic selected as a model pollutant of emerging concern. The second-order reaction rate constants of ENO with hydroxyl radicals (HOau) and singlet oxygen (O-1(2)) were determined at pH 3, 7, and 9. Also, the rate constants of the electron transfer reaction between ENO and triplet states of chromophoric dissolved organic matter ((CDOM)-C-3{*}) are reported for the first time, based on anthraquinone-2-sulfonate (AQ2S) as CDOM proxy. The sunlight-driven direct and indirect ENO degradation in the presence of dissolved organic matter (DOM) is also discussed. The results show that direct photolysis, which occurs more rapidly at higher pH, along with the reactions with HOau and (3)AQ2S{*}, is the key pathway involved in ENO degradation. The ENO zwitterions, prevailing at pH 7, show k (ENO,) HOau, k (ENO,1O2), and k (ENO,3AQ2S{*}) of (14.0 +/- 0.8) x 10(10), (3.9 +/- 0.2) x 10(6), and (61.5 +/- 0.7) x 10(8) L mol(-1) s(-1), respectively, whose differences at pH 3, 7, and 9 are due to ENO pH-dependent speciation and reactivity. These k values, along with the experimental ENO photolysis quantum yield, were used in mathematical simulations for predicting ENO persistence in sunlit natural waters. According to the simulations, dissolved organic matter and water depth are expected to have the highest impacts on ENO half-life, varying from a few hours to days in summertime, depending on the concentrations of relevant waterborne species (organic matter, NO3 (-), NO2 (-), HCO3 (-)). (AU)

• FAPESP's process: 16/03695-8 - Environmental photochemical fate and degradation of antibiotics by membrane BIOREACTOR-OZONE integrated systems
• Grantee: Arlen Mabel Lastre Acosta
• Support Opportunities: Scholarships in Brazil - Post-Doctoral