Activation of peroxymonosulfate (PMS) by Co3O4 quantum dots decorated hierarchical C@Co3O4 for degradation of organic pollutants: Kinetics and radical-nonradical cooperation mechanisms

Persulfate-based advanced oxidation process (PS-AOP) is a promising technology for in-depth wastewater treatment. Here, Co 3 O 4 quantum dots (QDs) decorated hierarchical C@Co 3 O 4 (C@Co 3 O 4 -Q5) was prepared by a facile route. The crystalline structure, micrograph and chemical composition of C@Co 3 O 4 -Q5 were characterized by XRD, SEM, TEM and XPS. Taking Rhodamine B (RhB) as a model contaminant, the influences of process parameters on the degradation performance were evaluated. Detailed reaction kinetics investigation indicated that, at elevated temperatures higher than 30 °C, RhB degradation rate approximately follows this expression: r = 1.022 × 1 0 7 e x p ( - 47850 / R T ) [ R h B ] [ P M S ] 0.36 , whereas the real energies for catalytic activation ( Eac ) and heat activation ( Eah ) were 16.231 kJ·mol −1 and 31.62 kJ·mol −1 , respectively. Reactive oxygen species (ROS) quenching experiments and EPR tests suggested that not the general held radical SO 4 − but the downstream OH and the nonradical ROS 1 O 2 co-contribute to RhB mineralization. Meanwhile, PMS activation mechanisms referring to OH and 1 O 2 generation were elaborated based on XPS discussion. It was revealed that Co 3 O 4 quantum dots and oxygen functional groups and/or oxygen defects on carbon surface cooperate to generate ROS. Additionally, 5 successive cycles confirmed C@Co 3 O 4 -Q5′s high stability and reusability. These findings provided new insights into carbon-loaded QDs catalysts for PMS-mediated micropollutants removal.