Photo-induced oxidation of ceftriaxone by persulfate in the presence of iron oxides

Abstract

The present study focuses on degradation and mineralization of a third generation cephalosporin antibiotic ceftriaxone (CTA) in UVA- and UVC-induced persulfate (PS) system combined with heterogeneous (α-FeO(OH) and Fe3O4) activators. The CTA oxidation efficiency was investigated in buffered solution (pH 7.4) to stimulate the inhibitory properties of environmental and processed water matrices. Irrespective of the studied UV-induced persulfate system, the mineralization was less effective than CTA degradation. In turn, UVC-induced systems proved to be more effective than UVA-induced processes for decomposition of the target compound and removal of TOC. Accordingly, 2-h oxidation in UVA-induced systems resulted in partial decomposition and negligible mineralization of CTA. While the application of UVC-activated persulfate processes resulted in complete CTA degradation during the first 15 min of oxidation with the most efficient kobs of 0.53 min−1 and 38.3% TOC removal obtained in the UVC/PS system at [PS]0 = 500 μM. Groundwater (GW) trials results clearly indicated the inhibitory effect of the GW composition on the effectiveness of CTA degradation in the studied UV-induced PS-based systems, while the potential treatment efficacy in GW proved predictable based on the results obtained in the buffered UW trials. Adjusting the pH to 3 considerably improved the removal of TOC and the use of PS in both of the water matrices studied. The results of radicals scavenging experiments indicated that both SO4− and HO contributed to the CTA decomposition efficacy in the UV-induced persulfate systems, but the former was the predominant radical in all studied processes. The findings of the study strongly suggest that the UV-induced PS systems are promising treatment technologies for the abatement of cephalosporin antibiotics pollution in natural aqueous matrices.