3.4.2. OzonationCompared to UV254 p

3.4.2. Ozonation
Compared to UV254 photolysis, ozonation was much more efficient in degrading the four antibiotics (see Fig. 5). OFL, AZI, and ROX were degraded with removal efficiencies above 99% after 10 min, while the same removal efficiency for NOR was obtained after 20 min. The ozonation rate of NOR was slower than those of the other three antibiotics, especially in the first 5 min. The reason should be that the diversity of structures of the four antibiotics resulted in different ozone affinity.

During ozonation, oxidation of pollutants could occur through ozone or radical dotOH, which was dependant on the ratio of ozone and radical dotOH concentration, the corresponding kinetics, the background of the treated water, etc. [36] and [37]. However, there was no significant characteristic signal of radical dotOH could be observed in the EPR spectrum of ozonation process. Thus, ozone was believed to be the main reactive species during ozonation of antibiotics in our experiments. Ozone is a selective oxidant and attacks certain functional groups such as Cdouble bond; length as m-dashC double bonds, activated aromatic systems and non-protonated amines, which are electron-rich functional groups [36]. It has been suggested that N(4) (see Fig. 1) is the main site that O3 attacks during ozonation of fluoroquinolones [37] and [38]. However, compared to secondary amine, tertiary amine, in which a methyl group results in a higher electron density at N(4) site, shows a higher ozone affinity and a faster ozonation rate [36] and [39]. Among the four antibiotics, NOR contains a secondary amine, while the other three have tertiary amines, which is the reason for a slower ozonation rate of NOR than those of the other three.

In addition, fluoroquinolones’ reactivity toward O3 is strongly dependent on pH, which is intrinsically governed by deprotonation of N(4) amine [37]. The difference in pKa2 values makes NOR and OFL exhibit different ionization behaviours at a certain pH, and consequently leads to different protonated states of the amine groups. The pKa2 values of NOR and OFL are 8.85 and 7.65, respectively [40]. Therefore, during the ozonation of NF concentrate at pH around 7.9, NOR exhibited neutral or zwitterionic forms, whereas OFL exhibited anionic forms that resulted in a deprotonated amine at N(4) site. Thus, it led to a faster reaction rate for OFL than that for NOR. In fact, it was demonstrated by Márquez et al. that the increasing pH of the solution led to an increasing reactivity of molecular ozone towards OFL [41]. The second-order rate constants (kO3-OFL) of OFL-ozone reaction were 2.0 × 106 and 1.2 × 107 M−1 s−1 at pH 7 and 8, respectively.

Both AZI and ROX were effectively degraded during ozonation. It was in accordance with the previous report that AZI and ROX were fast-reacting substrates towards O3 with apparent second-order rate constants (kO3, app) of 5.2 × 105 and 3.1 × 105 M−1 s−1 at pH 7.7 [37].

ผลลัพธ์ (อังกฤษ) 2:

3.4.2. Ozonation
Compared to UV254 photolysis, Ozonation was much more efficient in degrading The Four Antibiotics (See Fig. 5). OFL, AZI, and ROX were degraded with removal efficiencies above 99% after 10 min, while the same removal efficiency for NOR was obtained after 20 min. The ozonation rate of NOR was slower than those of the other three antibiotics, especially in the first 5 min. The Reason should be that The diversity of Structures of The Four Antibiotics resulted in different Ozone Affinity. During Ozonation, oxidation of pollutants could occur Through Ozone or Radical DotOH, which was Dependant on The ratio of Ozone and Radical DotOH Concentration, The corresponding Kinetics,. the background of the treated water, etc. [36] and [37]. However, there was no significant characteristic signal of radical dotOH could be observed in the EPR spectrum of ozonation process. Thus, ozone was believed to be the main reactive species during ozonation of antibiotics in our experiments. Ozone is a selective oxidant and attacks certain functional groups such as Cdouble bond; length as m-dashC double bonds, activated aromatic systems and non-protonated amines, which are electron-rich functional groups [36]. It has been suggested that N (4) (see Fig. 1) is the main site that O3 attacks during ozonation of fluoroquinolones [37] and [38]. However, compared to secondary amine, tertiary amine, in which a methyl group results in a higher electron density at N (4) site, shows a higher ozone affinity and a faster ozonation rate [36] and [39]. Among The Four Antibiotics, NOR Contains a Secondary Amine, while The Other Three Have Tertiary Amines, which is The Reason for a slower Ozonation rate of NOR than those of The Other Three. In addition, fluoroquinolones' reactivity toward O3 is Strongly dependent on pH. , which is intrinsically governed by deprotonation of N (4) amine [37]. The difference in pKa2 values ​​makes NOR and OFL exhibit different ionization behaviours at a certain pH, and consequently leads to different protonated states of the amine groups. The pKa2 values ​​of NOR and OFL are 8.85 and 7.65, respectively [40]. Therefore, during the ozonation of NF concentrate at pH around 7.9, NOR exhibited neutral or zwitterionic forms, whereas OFL exhibited anionic forms that resulted in a deprotonated amine at N (4) site. Thus, it led to a faster reaction rate for OFL than that for NOR. In fact, it was demonstrated by Márquez et al. that the increasing pH of the solution led to an increasing reactivity of molecular ozone towards OFL [41]. The Second-Order rate constants (KO3-OFL) of OFL-Ozone Reaction were 2.0 × 106 and 1.2 × 107 M-1 S-1 at pH 7 and 8, respectively. Both AZI and ROX were degraded during Ozonation Effectively. It was in accordance with the previous report that AZI and ROX were fast-reacting substrates towards O3 with apparent second-order rate constants (kO3, app) of 5.2 × 105 and 3.1 × 105 M-1 s-1 at pH 7.7 [37. ].

ผลลัพธ์ (อังกฤษ) 3:

3.4.2. Ozonation
Compared to, UV254 photolysis ozonation was much more efficient in degrading the four antibiotics (see. Fig. 5). OFL AZI, and ROX, were degraded with removal efficiencies above 99% after 10 min while the, same removal efficiency. For NOR was obtained after 20 min. The ozonation rate of NOR was slower than those of the other, three antibiotics especially. In the first 5 min.The reason should be that the diversity of structures of the four antibiotics resulted in different ozone affinity.

During. Ozonation oxidation of, pollutants could occur through ozone or, radical dotOH which was dependant on the ratio of ozone. And radical dotOH concentration the kinetics, corresponding, background the of the, treated water etc. [] []. 36 and 37, HoweverThere was no significant characteristic signal of radical dotOH could be observed in the EPR spectrum of ozonation, process. Thus ozone was, believed to be the main reactive species during ozonation of antibiotics in our experiments. Ozone is a. Selective oxidant and attacks certain functional groups such as Cdouble bond; length as m-dashC, double bondsActivated aromatic systems and, non-protonated amines which are electron-rich functional groups [36]. It has been suggested. That N (4) (see Fig. 1) is the main site that O3 attacks during ozonation of fluoroquinolones [] []. 37 and 38 However compared,, To secondary, amine amine tertiary, which in a methyl group results in a higher electron density at N (4), siteShows a higher ozone affinity and a faster ozonation rate [] []. 36 and 39 Among the, four antibiotics NOR contains a secondary. Amine while the, other three have tertiary amines which is, the reason for a slower ozonation rate of NOR than those of. The other three.

In addition fluoroquinolones', reactivity toward O3 is strongly dependent, on pHWhich is intrinsically governed by deprotonation of N (4) amine [37]. The difference in pKa2 values makes NOR and OFL exhibit. Different ionization behaviours at a, certain pH and consequently leads to different protonated states of the amine, groups. The pKa2 values of NOR and OFL are 8.85 and 7.65 respectively []. Therefore, 40, the during ozonation of NF concentrate at. PH, around 7.9NOR exhibited neutral or zwitterionic forms whereas OFL, exhibited anionic forms that resulted in a deprotonated amine. At N (4), site. Thus it led to a faster reaction rate for OFL than that for NOR. In fact it was, demonstrated by M and rquez. Et al. That the increasing pH of the solution led to an increasing reactivity of molecular ozone towards 41 OFL [].The second-order rate constants (kO3-OFL) of OFL-ozone reaction were 2.0 × 106 and 1.2 × 107 M − 1 s − 1 at pH 7, and 8 respectively.

Both. AZI and ROX were effectively degraded during ozonation. It was in accordance with the previous report that AZI and ROX were. Fast-reacting substrates towards O3 with apparent second-order rate constants (kO3 APP), of 5.2 × 105 and 3.1 × 105 M − 1. S − 1 at pH 7.37 7 [].