Degradation of ofloxacin with heterogeneous photo-Fenton catalyzed by biogenic Fe-Mn oxides

Ofloxacin (OFL), a typical fluoroquinolone antibiotic, has been frequently detected in the aquatic environment and may cause potential ecological risks. In this work, biogenic Fe-Mn oxides (bio-FeMnOx) were produced by Pseudomonas sp. F2. The harvested bio-FeMnOx mainly consisted of gamma-Fe2O3 and a mix valence of Mn2+, Mn3+ and Mn4+ and was applied for the first time to catalyze the heterogeneous photo-Fenton for the degradation of OFL as a model organic contaminant. It was found that bio-FeMnOx exhibited a 2-fold higher catalytic activity than chemically synthesized Fe-Mn oxides: pseudo-first-order kinetic constant 3.41 x 10(-2) min(-1) vs 1.53 x 10(-2) min(-1), respectively. The scavenger study indicated the substantial participation of hydroxyl radical (OH center dot), electron (e(-)) and hole (h(+)) in the degradation of OFL but a negligible involvement of superoxide radical anion (O-2(center dot-)). Possible intermediates were identified with HPLC-MS, revealing that the degradation may involve the reactions of hydrolysis, dehydration, dealkylation, and C=C breakage. In addition, nearly 50% of the biological respiration inhibition of OFL was removed after the heterogeneous photo-Fenton over bio-FeMnOx.