The effects of dissolved O2, phosphate buffer and the initial concentration of diclofenac on the vacuum ultraviolet photolysis of this contaminant molecule were studied. Besides kinetic measurements, the irradiated, multicomponent samples were characterized via the proliferation and migratory responses (in sublethal concentrations) of the bioindicator eukaryotic ciliate Tetrahymena pyriformis. The results suggest that hydroxyl radicals, hydrogen atoms and hydroperoxyl radicals may all contribute to the degradation of diclofenac. The aromatic by-products of diclofenac were presumed to include a hydroxylated derivative, 1-(8-chlorocarbazolyl)acetic acid and 1-(8-hydroxycarbazolyl)acetic acid. The biological activity of photoexposed samples reflected the chemical transformation of diclofenac and was also dependent on the level of dissolved O2. The increase in toxicity of samples taken after different irradiation times did not exceed a factor of two. Our results suggest that the combination of vacuum ultraviolet photolysis with toxicity and chemotactic measurements can be a valuable method for the investigation of the elimination of micropollutants.
Keywords: AOP; Advanced oxidation process; Chemotaxis; Chemotaxis Index; Chtx. Ind; DICL; Hydroxyl radical; Nonsteroidal anti-inflammatory drug; PB; PhAC; Photodegradation; R(); ROO(); SE; Toxicity; WWTP; [HO()](SS); advanced oxidation process; apparent reaction rate constant; carbon-centered radical; diclofenac; k; k(DICL); k′; peroxyl radical; pharmaceutically active compound; phosphate buffer; r(DICL); reaction rate between DICL and HO(); reaction rate between H(2)PO(4)(−) and HO(); reaction rate between HPO(4)(2−) and HO(); reaction rate constant; second-order reaction rate constant between DICL and HO(); second-order reaction rate constant between H(2)PO(4)(−) and HO(); second-order reaction rate constant between HPO(4)(2−) and HO(); standard errors of the mean; the steady-state concentration of hydroxyl radicals; wastewater treatment plant.
© 2013.