Ru-Modified α-MnO2 as an Efficient PMS Activator for Carbamazepine Degradation: Performance and Mechanism

Although Ru-based catalysts have been investigated in various oxidation systems, their application in sulfate radical-based AOPs, particularly as heterogeneous activators for acidic wastewater treatment, remains limited. Herein, Ru was incorporated into α-MnO2 via lattice doping and surface loading to construct Rulatt/α-MnO2 and Rusurf/α-MnO2, and their PMS activation performance toward carbamazepine (CBZ) degradation was evaluated. Rulatt/α-MnO2 exhibited superior activity, achieving near-complete CBZ removal within minutes under acidic conditions. PMS dosage, catalyst loading, and pH affected the degradation efficiency, with acidic environments significantly enhancing PMS activation. Cl− slightly promoted CBZ degradation, whereas HCO3− and natural organic matter inhibited it. Mechanistic analysis revealed that Ru activated PMS through a nonradical pathway, continuously generating 1O2 via a reversible Ru (II)/Ru (III)/Ru (IV) cycle, while the Mn (III)/Mn (IV) redox couple acted as an electron buffer to sustain Ru cycling and improve durability. The catalyst maintained high activity in complex water matrices, demonstrating strong potential for practical remediation of CBZ-contaminated acidic wastewater.