A stable and easily prepared copper oxide catalyst for degradation of organic pollutants by peroxymonosulfate activation

A direct one-step calcination preparation of CuO catalyst (CuO-3) using polyethylene glycol (PEG) as nonionic polymeric structure directing agent was developed for activation of peroxymonosulfate (PMS). The morphological and physicochemical properties of the CuO-3 were characterized and the catalytic activity for degradation of organic pollutants was evaluated. The resultant CuO-3 with significantly enhanced surface area exhibited excellent catalytic performance of phenolic organic pollutants degradation. The reaction mechanism of the PMS/CuO system was systematically investigated with a series of radical quenching tests and the analysis of electron paramagnetic resonance (EPR) spectroscopy. Quite different from traditional hydroxyl radicals ((OH)-O-center dot) and sulfate radical (SO4 center dot-) based advanced oxidation processes, singlet oxygen (O-1(2)) was identified as the dominate reactive species responsible for the degradation of organic pollutants. Moreover, the main formation pathway of O-1(2) was also investigated. The results indicated that the superoxide radical (O-2(center dot-)) was involved in the generation of O-1(2) as a crucial precursor. Also, the PMS/CuO-3 system exhibited satisfactory stability and reusability under neutral conditions as well as high removal of organic pollutants in the presence of inorganic anions. This work not only provides a novel and stable preparation method for CuO catalyst, but also gives a deeper insight into the mechanisms of PMS activation by CuO.