Enhanced oxidation of erythromycin by persulfate activated iron powder–H 2 O 2 system: Role of the surface Fe species and synergistic effect of hydroxyl and sulfate radicals

Abstract Erythromycin (ERY) is one of macrolide antibiotics which are hardly removed by conventional water treatment process. In this study, the degradation of ERY using a H 2 O 2 and persulfate combined process was assessed. Neutral and acidic conditions are superior to alkaline condition in the results of ERY degradation. The Cl − exhibited dual effects (favorable or adverse) distinctively on ERY degradation, while HCO 3 − , CO 3 2− and humic acid significantly inhibited ERY degradation. The results showed that with the persulfate/H 2 O 2 molar ratio improved from 0:10 to 1:9 (total oxidants dosage was 0.1 mM), the ERY degradation efficiency increased from 6.5% to 90.0%. Effective oxidation of ERY only occurred after adding persulfate with the formation of surface-associated Fe(II) on the ZVI surface facilitating rapid and extensive decomposition of H 2 O 2 . Undetectable concentration of dissolve Fe 2+ suggested that the generation of HO was mainly from the surface-located Fe(II)-initiated heterogeneous Fenton process. The intermediate products during oxidation were identified, and the degradation pathways of ERY were tentatively proposed.