How does pH influence ferrate(VI) oxidation of fluoroquinolone antibiotics?

This study investigated the impact of pH on the efficiency of ferrate (Fe(VI), K2FeO4) toward fluoroquinolone antibiotics, built kinetic models of Fe(VI) oxidation, and elucidated the involved active species during Fe(VI) oxidation at acidic and alkaline conditions. It was found that the second-order reaction rate constants (k(app), M-1 s(-1)) of Fe(VI) with three fluoroquinolone antibiotics (i.e., enroxacin, ofloxacin, and norfloxacin) were strongly dependent on pH, and k(app) reached its maximum at pH about 6.5. The reactions between HFeO4-/H2FeO4 and neutral/protonated fluoroquinolone antibiotics (X and XH+) were the major ones. Moreover, the reactive species were identified as high-valent iron species, i.e., Fe(VI), Fe(V), and Fe(IV), in alkaline solution, while hydroxyl radicals was generated through Fenton or Fenton-like processes at acidic condition with limited contribution.

Automated summary

The study found that the reaction rate of Fe(VI) with fluoroquinolone antibiotics is strongly dependent on pH, reaching its maximum at around pH 6.5. In alkaline solution, high-valent iron species were identified as the major reactive species, while hydroxyl radicals were generated through Fenton or Fenton-like processes in acidic conditions with limited contribution.