Oxidative degradation of thiocyanate via activation of persulfate by CuO/α-MnO2 composite: Effect of calcination temperature

In this study, a highly efficient CuO/α-MnO 2 bimetallic catalyst was synthesized by hydrothermal and calcination methods and employed as a peroxydisulfate (PDS) activator for the degradation of thiocyanate (SCN − ) in aqueous phase. The effect of calcination temperature on the catalytic performance of CuO/α-MnO 2 and the mechanism of the CM350/PDS system were studied. Under optimal conditions, almost 100 % of SCN − (100 mg/L) was degraded within 90 min. XRD , XPS , Raman, and H 2 -TPR analyses revealed that the catalytic performance was enhanced in the CM350 catalyst due to the formation of M-O-Cu + -like structures (M = Mn 3+ , Mn 4+ , Cu 2+ ) through the combination of α-MnO 2 with CuO . The structures exhibit excellent redox ability and facilitate electron transfer between Cu and Mn elements, thereby improving the activation effect of PDS. Besides, the Cu 1.5 Mn 1.5 O 4 generated from the high calcination temperature was not conducive to the SCN − degradation reaction. Moreover, the mechanism study indicated that SO 4 ·- , ·OH, and the electron transfer pathway mainly accounted for the SCN − degradation. This study provides some guidance for the synthesis of PDS activation materials and the treatment of industrial wastewater by an advanced oxidation process .