Mn-Co/ɣ-Al2O3 coupled with peroxymonosulfate as efficient catalytic system for degradation of norfloxacin

Abstract

As one of the most widely used antibiotics, fluoroquinolones (FQs) are frequently detected in water resources, posing a severe threat to human health and ecological environment. In the present study, Mn-Co/ɣ-Al2O3 material was synthesized as a highly effective activator for peroxymonosulfate (PMS) to degrade the typical FQs norfloxacin (NOR). The degradation efficiency of NOR was up to 90.7 % within 60 min using 2.0 mM PMS and 0.10 g/L Mn-Co/ɣ-Al2O3 at pH 6.6 and 25 °C. The NOR degradation obeyed pseudo-first-order reaction kinetics. High PMS concentration and temperature could enhance the NOR degradation. The presence of Cl− and humic acid could reduce the NOR degradation, whereas the NOR transformation was promoted with the addition of HCO3−. The degradation efficiencies (82.0–88.7 %) of other three FQs (ciprofloxacin, ofloxacin and enrofloxacin) showed the Mn-Co/ɣ-Al2O3 activated PMS process could be applied to remove the FQs. The degradation efficiencies of NOR (79.0–90.7 %) and the total organic carbon (TOC) removal rates (71.9–86.6 %) in the five continuous applications of Mn-Co/ɣ-Al2O3 indicated that Mn-Co/ɣ-Al2O3 has stable applicability in the PMS-based system. Radical scavenger experiments demonstrated that reactive species SO4−, OH and 1O2 were involved in the degradation process of NOR. The possible degradation pathways of NOR were speculated based on eleven identified products. Overall, the Mn-Co/ɣ-Al2O3 activated PMS process is an efficient method for rapid remediation of the FQs contaminated water.