Activation of peroxymonosulfate (PMS) by Co3O4 quantum dots decorated hierarchical C@Co3O3 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, Co3O4 quantum dots (QDs) decorated hierarchical C@Co3O4 (C@Co3O4-Q5) was prepared by a facile route. The crystalline structure, micrograph and chemical composition of C@Co3O4-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 degrees C, RhB degradation rate approximately follows this expression: r = 1.022 x 10(7)exp(-47850/RT)[RhB][PMS](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 SO4 center dot- but the downstream (OH)-O-center dot and the nonradical ROS O-1(2) co-contribute to RhB mineralization. Meanwhile, PMS activation mechanisms referring to (OH)-O-center dot and O-1(2) generation were elaborated based on XPS discussion. It was revealed that Co3O4 quantum dots and oxygen functional groups and/or oxygen defects on carbon surface cooperate to generate ROS. Additionally, 5 successive cycles confirmed C@Co3O4-Q5's high stability and reusability. These findings provided new insights into carbon-loaded QDs catalysts for PMS-mediated micropollutants removal.

Automated summary

The study prepared a Co3O4 quantum dots decorated hierarchical C@Co3O4 material and comprehensively characterized its performance and degradation efficiency. The results showed that under specific conditions, the material exhibited strong degradation performance towards Rhodamine B, with high stability and reusability.