Oseltamivir is widely used as an antiviral drug and it has been a concern in the aquatic environment. In this study, the degradation mechanisms of oseltamivir were investigated in UV photolysis and UV/H2O2 reactions. The effects of pH, temperature, humic acid, H2O2 concentration, and inorganic anions such as chloride (Cl-), bicarbonate (HCO3-), and nitrate (NO3-) on the degradation kinetics were examined. The degradation kinetics of each reaction followed the pseudo-first-order. UV/H2O2 reaction showed a higher removal than UV photolysis due to the effective generation of OH radicals. The contribution of OH radicals at different pHs was determined by using nitrobenzene (NB) as a radical scavenger. OH radicals contributed 88% at pH 6.5, showing the highest contribution than pH 3.5 (79%) and pH 9.5 (84%). 64% of total organic carbon (TOC) in oseltamivir was mineralized after 12 hours in UV/H2O2 reaction. Total of ten transformation byproducts (TPs) were identified using UPLC-Q-ToF/MS: six (m/z = 277.1, 327.2, 329.2, 347.2, 361.2, and 377.2) from UV/H2O2, two (m/z = 226.1, 244.2) from UV photolysis, and two (m/z = 261.1, 331.2) from both reactions. Based on the identified TPs, the degradation pathways were proposed. Additionally, bioluminescence inhibition in Vibrio fischeri during UV/H2O2 and UV photolysis reactions were evaluated.

Degradation of oseltamivir (Tamiflu) in UV photolysis and UV/H2O2 reactions: Performance, kinetics, and mechanism

ACS Fall 2021

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