Molecular levels unveil the membrane fouling mitigation mechanism of a superpotent N-rGO catalytic ozonation membrane: Interfacial catalytic reaction pathway and induced EfOM transformation reactions

This study investigated the membrane fouling self-cleaning of N-doped reduced graphene oxide (N-rGO)-tailored ceramic membrane with ozone (N-rGO-CM-O/F) at the molecular level. Density functional theoretical (DFT) revealed the principle of interfacial catalytic reaction, and the transformation of foulants was probed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and various spectroscopic techniques. Results showed that ozone could be aggregated on the N-rGO-CM surface and formed abundant •OH. This made humic acid-like substances blocking membrane pores to be sufficiently and preferentially removed in N-rGO-CM-O/F by 18-types reactions of catalytic ozonation. Conversely, CM-O/F preferentially removed protein-like substances that formed the cake layer. Due to the stronger catalytic ozonation ability and efficient fouling mitigation behavior, N-rGO-CM-O/F showed higher water flux as 1.96 times than that of CM-O/F. Overall, this study provided molecular insight into the mechanism of membrane fouling mitigation, which will facilitate the design and application of advanced catalytic membranes.