Degradation of Doxycycline, Enrofloxacin, and Sulfamethoxypyridazine under Simulated Sunlight at Different pH Values and Chemical Environments

In this work, the dissipation of antibiotics doxycycline (DC) (from group tetracyclines), enrofloxacin (ENR) (a fluoroquinolone), and sulfamethoxypyridazine (SMP) sulfonamide) is investigated both under simulated sunlight in dark, at three different pH (4.0, 5.5, 7.2), presence salts humic acids. The results indicate that all are very sensitive to photodegradation, sensitivity increased with rising values, from 4.0 7.2. rise also caused an increase degradation kinetic constants a decrease half-lives antibiotics. general, ranged few minutes 6 h, depending on conditions specific antibiotic, followed sequence DC > SMP ENR, although 5.5 changed ENR. After 24 h sunlight, mineralization was always lower than 10%, antibiotic not quantifiable after same time exposure light (24 h), which indicates intermediate compounds were generated. effect negligible for NaCl NaNO3, while NaHCO3 did favor acids showed no SMP, it only slightly These may be useful assessment persistence/degradation studied when they reach environmental compartments suffer physicochemical conditions.