The organic contaminants degradation in Mn-NRGO and peroxymonosulfate system: The significant synergistic effect between Mn nanoparticles and doped nitrogen

A family of graphene-based activators including reduced graphene oxide (RGO), nitrogen doped reduced graphene oxide (NRGO), zero-valent manganese loaded reduced graphene oxide (Mn-RGO) and zero-valent manganese loaded N-doped reduced graphene oxide (Mn-NRGO) were fabricated to activate peroxymonosulfate (PMS) for bisphenol A (BPA) degradation. A significant synergistic effect between loaded manganese nano-particles (Mn-NPs) and doped N was revealed by comparing the apparent reaction rate constants with about 12.4, 7.6 and 10.5-folds enhancement when compared Mn-NRGO with RGO, NRGO, Mn-RGO, respectively. By integrating the results of chemical scavenger experiment, electron paramagnetic resonance test, galvanic oxidation process, PMS stoichiometric efficiency, linear sweep voltammetry and in-situ Raman spectrum, a predominant outer-sphere catalyst-PMS complexes mediated electron transfer pathway was uncovered. Based on kinetic studies, the specific contribution of synergistic effect was quantified to be at least 70%. The calculated Fermi level advanced by 0.03 eV in Mn-NG compared with that in NG, demonstrating that Mn-NG is more liable to donate electrons to PMS. The E ads and l O-O results pointed out that synergistic effect between Mn-NPs and doped N relied on the intimate affinity between Mn-NPs and HSO 5 – which triggered more uneven distribution of charge on the whole carbon sheets, and more adsorption of HSO 5 – on carbon framework. These newly created adsorption consequently reinforcing the formation of catalyst-PMS complexes and the elevation of mediated electron transfer pathway. Overall, this study firstly provides a comprehensive and definite insight of the synergistic effect between loaded Mn-NPs and doped-N on carbon materials for promoting PMS activation to degrade organics.