Activation of peroxymonosulfate by MnOOH/g-C3N5: Study on highly selective removal of phenolic pollutants and its non-radical pathway

In this research, the MnOOH/g-C3N5 material was successfully synthesized, demonstrating its efficacy in selectively removing phenolic organic pollutants. This material outperformed traditional free radical pathways, exhibiting higher selectivity, enhanced persulfate utilization efficiency, and strong resistance to background anions and complex organic matter. Using phenol as the target pollutant, the MnOOH/g-C3N5/PMS system achieved 81 % mineralization, a PMS utilization efficiency of 88%, and a 75% process unit energy consumption value in degrading phenol. This efficient degradation is attributed to the synergistic effects of high-valence metal oxides (MnV(O)/MnIV(O)), singlet oxygen (1O2), and electron transfer complexes, as confirmed by electrochemical analysis and In-situ EPR. Additionally, Transmission Electron Microscopy observations disclosed the development of an amorphous shell on the MnOOH/g-C3N5 surface post-reaction. Electrochemical Impedance Spectroscopy analysis suggested an enhanced charge transfer resistance, further affirming the role of MnOOH/gC3N5 as an "electron transfer station" in the electron transfer process, accompanied by the formation of electron transfer complexes. This study provides crucial scientific insights and theoretical guidance for applying MnOOH/ g-C3N5 materials in environmental engineering.