Epsilon-MnO2 simply prepared by redox precipitation as an efficient catalyst for ciprofloxacin degradation by activating peroxymonosulfate

Abstract

Four kinds of manganese oxides were successfully prepared by hydrothermal and redox precipitation methods, and the obtained oxides were used for CIP removal from water by activating PMS. The microstructure and surface properties of four oxides were systematically characterized. The results showed that ε-MnO2 prepared by the redox precipitation method had large surface area, low crystallinity, high surface Mn(III)/Mn(Ⅳ) ratio and the highest activation efficiency for PMS, that is, when the concentration of PMS was 0.6 g/L, 0.2 g/L ε-MnO2 could degrade 93% of CIP within 30 min. Multiple active oxygen species, such as sulfate radical, hydroxyl radical and singlet oxygen, were found in CIP degradation, among which sulfate radical was the most important one. The degradation reaction mainly occurred on the surface of the catalyst, and the surface hydroxyl group played an important role in the degradation. The catalyst could be regenerated in situ through the redox reaction between Mn4+ and Mn3+. The ε-MnO2 had the advantages of simple preparation, good stability and excellent performance, which provided the potential for developing new green antibiotic removal technology. HIGHLIGHTS Epsilon-MnO2 nanoflowers were simply prepared by the redox precipitation method.; Epsilon-MnO2 nanoflowers were used to activate PMS to degrade CIP in water.; The high activity of ε-MnO2 was due to its large surface area, low crystallinity and high surface Mn(III)/Mn(Ⅳ) ratio.; The –OH groups on the surface could promote the activation of PMS.;

Keywords

• ciprofloxacin
• degradation
• manganese (hydroxyl) oxide
• peroxymonosulfate
• reactive oxygen species