Degradation of phenazone in aqueous solution with ozone: Influencing factors and degradation pathways

High-resolution MS and MSn investigation of ozone oxidation products from phenazone-type pharmaceuticals and metabolites

“…In addition, it is also subject to hydroxylation, forming P11 as a minor product. P10, which was observed as a major degradation product in our study, was also reported by Miao et al (2015).…”

“…P5 -a minor degradation product in the case of AAA and FAAcan further lead to P3 as suggested by Gómez et al (2008) by the loss of the oxamoyl functional group or to P10 by hydroxylation as suggested by Miao et al (2015). From the work done by Gómez et al (2008) on the photodegradation of 4-Methylaminoantipyrine, another metabolite of dipyrone, an additional degradation product was identified: P3 can lose the methyl group attached to the carbonyl and lead to 1-acetyl-1-methyl-2-phenylhydrazide (P8).…”

“…This parameter is chosen over the empirical first-order rate constant À used by Miao et al (2015) in a recent study investigating the degradation of PZ by ozone À as it can be a valuable parameter for ozone dose determinations in full-scale waste water treatment processes.…”

“…Miao et al (2015) also investigated the toxicity of P3 using another QSAR model to find that P3 was slightly less toxic than PZ for Daphnid (LC50 at 48 h). This illustrates that QSAR models are not meant to provide exact values and replace empirical determination but rather to guide further research.…”

Fast removal of the antibiotic flumequine from aqueous solution by ozonation: Influencing factors, reaction pathways, and toxicity evaluation

“…Ozone can react with organic pollutants through direct reaction (known as ozonolysis) and/or indirect reactions with OH•, which are produced by O 3 decomposition (Mawhinney et al, 2012;Chang et al, 2014). During aqueous ozonation, OH• reacts non-selectively with most of the organic compounds, whereas O 3 , being electrophilic, reacts selectively with the electron-rich reaction sites of organic compounds, such as unsaturated double bonds and aromatic rings (Miao et al, 2015). Therefore, organic compounds in water may be decomposed by both O 3 and OH• through a series of oxidation and radical reactions involving a variety of mechanisms, such as the Criegee mechanism, electrophilic substitution, hydrogen abstraction and electron abstraction (Mawhinney et al, 2012;Miao et al, 2015;Tay and Madehi, 2015).…”