Novel MnCo2O4.5@manganese sand for efficient degradation of tetracycline through activating peroxymonosulfate: Facile synthesis, adaptable performance and long-term effectiveness

Mn-Co bimetallic oxides@manganese sand (MC@MS) was successfully synthesized and used as a heterogeneous peroxymonosulfate (PMS) activator for the first time. The relationship between catalyst performance and preparation conditions was discussed, and 450-1.5MC@MS exhibited superior performance. 450-1.5MC@MS had excellent adaptability to the treatment conditions, and it was further confirmed that HPO42-could signifi-cantly improve the utilization of PMS in the system thus promoting tetracycline (TC) degradation. In addition, 450-1.5MC@MS possessed superior stability, with only a 15.7% decrease in TC degradation efficiency after five cycles. Moreover, the catalytic activity of 450-1.5MC@MS could be easily recovered to that of the first round basically by calcination at 300 celcius. More importantly, the continuous-flow column reaction experiments showed that 450-1.5MC@MS had excellent working life, only 15 g catalyst could continuously treat 13.5 L TC solution with an acceptable removal efficiency. MS can also promote PMS activation due to the participation of Mn(II)/ Mn(III)/Mn(IV) redox cycle. Besides, sulfate radicals (SO4 center dot-) and singlet oxygen radicals (1O2) were identified as the predominant reactive oxygen species driving TC degradation. In brief, this study reports a novel and envi-ronmentally friendly catalyst that has great application potential for the treatment of organic wastewater.