CN-Mn/CNT composite as a heterogeneous catalyst in the electro-peroxone process for promoting the reaction between O and HO in acid solution

The electro-peroxone (E-P) process normally exhibits low efficiency in organic degradation in acid solution due to the limited rate constant of the reaction between O 3 and H 2 O 2 (peroxone reaction). In this paper, a C 3 N 4 -Mn/CNT composite material was synthetized and characterized with XRD, FTIR, SEM and XPS. With the function of the C 3 N 4 -Mn/CNT catalyst, the substrate oxalic acid (OA) was completely degraded in the E-P process within 30 min at pH 3, while only 15% degradation could be achieved after 60 min without the catalyst. The comparison of different reaction systems using the C 3 N 4 -Mn/CNT catalyst confirmed that the catalyst promoted the peroxone reaction, rather than the catalytic ozonation or electro-Fenton like reaction. Correlating the XRD and XPS analysis with the degradation data using the C 3 N 4 -Mn/CNT catalyst, we deduced that Mn coordinated with nitrogen was the active site for the peroxone reaction. Furthermore, the catalyst showed good chemical and catalytic stability in five cycles of the E-P process for OA degradation. The C 3 N 4 -Mn/CNT catalyst promotes the reaction between O 3 and H 2 O 2 in acid solution, and enhances the degradation efficiency of the electro-peroxone process.