Liquid chromatography time-of-flight mass spectrometry (UPLC/ESI-QToF-MS) was used for the elucidation of the main transformation products (TPs) resulting from the degradation of diclofenac (DCF) and ibuprofen (IBP) during the application of various advanced oxidation processes in aqueous matrices. The examined processes were TiO 2 photocatalysis driven by UV-A or simulated solar irradiation, sonolysis, and UV-A photocatalysis integrated with ultrasound irradiation (sonophotocatalysis). A comparison between the applied treatment processes was performed with respect to the substrates first-order kinetic rate constant. When compared with sonolysis and UV-A photocatalysis, a higher degradation rate was observed for sonophotocatalysis in the presence of 500 mg L −1 TiO 2 . Seven TPs of IBP and ten TPs of DCF under UV-A and simulated solar irradiation photocatalysis and sonophotocatalysis, formed by consecutive attack of hydroxyl radicals (HO • ) in concomitance with the degradation of the primary compounds, were tentatively identified. Overall, no differences were observed in the nature of TPs formed for each substrate among the experiments performed, indicating the involvement of similar reaction mechanisms. The degradation pathway of IBP includes mainly decarboxylation, demethylation and hydroxylation reactions, while the oxidation of DCF, mainly proceeded by oxidation and hydroxylation reactions between chloroaniline and phenylacetic acid. An important observation made during the experiments was that the hydroxylated species (1 -OH-IBP; 2 -OH-IBP; 4 -OH-DCF; 5 -OH-DCF) remained in the solution until 120 min. Finally, the results demonstrated the capacity of the sonophotocatalysis to reduce the initial toxicity of IBP and DCF aqueous solutions against the water flea Daphnia magna yielding 20% and 40% immobilization, respectively, at the end of the treatment.
This work investigated the application of a solar driven advanced oxidation process (solar Fenton), for the degradation of the antibiotic ofloxacin (OFX) in various environmental matrices at a pilot-scale. All experiments were carried out in a compound parabolic collector pilot plant in the presence of doses of H2O2 (2.5 mg L(-1)) and at an initial Fe(2+) concentration of 2 mg L(-1). The water matrices used for the solar Fenton experiments were: demineralized water (DW), simulated natural freshwater (SW), simulated effluent from municipal wastewater treatment plant (SWW) and pre-treated real effluent from municipal wastewater treatment plant (RE) to which OFX had been spiked at 10 mg L(-1). Dissolved organic carbon removal was found to be dependent on the chemical composition of the water matrix. OFX mineralization was higher in DW (78.1%) than in SW (58.3%) at 12 mg L(-1) of H2O2 consumption, implying the complexation of iron or the scavenging of hydroxyl radicals by the inorganic ions present in SW. On the other hand, the presence of dissolved organic matter (DOM) in SWW and RE, led to lower mineralization per dose of H2O2 compared to DW and SW. The major transformation products (TPs) formed during the solar Fenton treatment of OFX, were elucidated using liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS). The transformation of OFX proceeded through a defluorination reaction, accompanied by some degree of piperazine and quinolone substituent transformation while a hydroxylation mechanism occurred by attack of the hydroxyl radicals generated during the process leading to the formation of TPs in all the water matrices, seven of which were tentatively identified. The results obtained from the toxicity bioassays indicated that the toxicity originates from the DOM present in RE and its oxidation products formed during the photocatalytic treatment and not from the TPs resulted from the oxidation of OFX.
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