Hexagonal boron nitride-supported γ-MnO2 for reduced oxidant demand in the polymerization of phenolic pollutants

Abstract

Minimizing the oxidant input in heterogeneous Fenton-like reactions provides a practical strategy for reducing operational costs and abating secondary pollution. This study used hexagonal boron nitride (h–BN) as a support catalyst for γ–MnO2 to enhance the persulfate utilization during the oxidative polymerization of phenolic pollutants. Upon peroxymonosulfate (PMS) activation, γ–MnO2 generated surface-bound PMS, which directly abstracted electrons from pollutants, suppressing excessive oxidant consumption. Simultaneously, the h–BN support enriched bisphenol A (BPA) on the γ–MnO2-decorated h–BN (MnBN) surface via intermolecular interactions, accelerating the coupling/polymerization of oxidized pollutant intermediates. Consequently, MnBN achieved a high persulfate utilization efficiency (PUE; 87.7%), surpassing previously reported values, and a six-times-faster BPA removal rate (normalized to Mn content) than that of pristine γ–MnO2, along with a high polymerization transfer ratio of 95.3%. The critical role of the fast coupling/polymerization of oxidized intermediates, following direct electron transfer, in achieving a high PUE was systematically validated using structurally analogous phenolic pollutants. This study offers a strategy for dynamically minimizing chemical inputs in advanced oxidation processes and provides mechanistic insights into the interplay between pollutant structure and oxidant consumption.