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) and sulfate radical (SO4−) based advanced oxidation processes, singlet oxygen (1O2) was identified as the dominate reactive species responsible for the degradation of organic pollutants. Moreover, the main formation pathway of 1O2 was also investigated. The results indicated that the superoxide radical (O2−) was involved in the generation of 1O2 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.