Efficient degradation of norfloxacin via MnCo-LDH/sepiolite activating peroxymonosulfate: performance, mechanism and degradation pathway

In this study, MnCo layered double hydroxide/sepiolite (MnCo-LDH/sepiolite) as PMS catalyst were synthesized using a simple water bath method. The results indicated that the composite exhibited the highest norfloxacin (NF) removal efficiency (90.14% in 40 min), and its reaction rate constant (0.2049 min-1) was 2.0 times higher than that of pure MnCo-LDH. Compared with MnCo-LDH, MnCo-LDH/sepiolite catalyst had a larger specific surface area and pore volume which can provide more abundant active sites thereby improving the NF degradation performance. In addition, EPR and quenching experiments results revealed that SO4•- and 1O2 were the main active substances. Moreover, the successive redox of Mn and Co species contributed to the main driving force to effectively activate PMS. Furthermore, the possible catalytic mechanisms and NF degradation pathways were systematically analyzed. Overall, this study provides a new strategy for developing an economical, efficient and environmentally friendly PMS catalyst for wastewater treatment.