Enhanced removal of lomefloxacin based on peroxymonosulfate activation by Co3O4/δ-FeOOH composite

Abstract In the present study, a novel Co 3 O 4 /δ-FeOOH composite was successfully fabricated. Subsequently, we measured its crystal structure, morphology, and surface area. After this, the Co 3 O 4 /δ-FeOOH composite was applied to activate peroxymonosulfate (PMS) for lomefloxacin (LOM, a type of fluoroquinolones) degradation. Compared with pure Co 3 O 4 and δ-FeOOH, Co 3 O 4 /δ-FeOOH composite exhibited the best efficiency towards LOM degradation, in which the removal of LOM (>82%) and first order reaction kinetic rate constant (k app  = 0.064 min −1 ) were achieved after 25 min reaction with 0.25 g·L −1 Co 3 O 4 /δ-FeOOH, 0.49 mM PMS, and 10 mg·L −1 (28.5 μM) LOM at initial pH 6.08. Next, we considered the concentration of catalyst, PMS and the effect of pH on LOM degradation. The results showed that the increase of PMS and catalyst was beneficial for the degradation of LOM. Moreover, the highest degradation efficiency of LOM was achieved under neutral conditions, which was due to the minimum repulsive force between the PMS and the catalyst. In addition, active radical scavenging experiment was performed and it was found that the contribution of hydroxyl radicals was greater than that of sulfate radicals. Subsequently, possible reaction mechanism was proposed. What’s more, possible degradation intermediates in Co 3 O 4 /δ-FeOOH system were determined and five decomposition pathways were proposed. Meanwhile, activated sludge inhibition experiment was carried out to evaluate the variation of toxicity of the LOM and its degradation intermediates in the oxidation process. Overall, this work provided a new strategy for the practical application of sulfate radicals-based advanced oxidation processes (SR-AOPs) in wastewater treatment.