Activation of peroxymonosulfate by magnetic carbon supported Prussian blue nanocomposite for the degradation of organic contaminants with singlet oxygen and superoxide radicals

In order to develop efficient and green catalyst for organic pollutants removal, magnetic carbon supported Prussian blue nanocomposite Fe3O4@C/PB was prepared for the first time. The performance of Fe3O4@C/PB in activating peroxymonosulfate (PMS) for the degradation of 2,4-dichlorophenol (2,4-DCP) was investigated. 2,4-DCP could be effectively degraded under the "Fe3O4@C/PB + PMS" system within a broad pH range of 2-9. Without pH adjustment (pH 3), 2,4-DCP (20 mg/L) was completely degraded in 50 min along with a 70% removal of TOC; while the required time for complete degradation of 2,4-DCP was shortened to 40 min under initial solution pH at 7. Fe3O4@C/PB could also activate PMS for the degradation of phenol, Acid Orange II, Reactive brilliant red X-3B, Rhodamine B and Methylene blue. The degradation rates higher than 95% could be achieved for all these contaminants within the time scale of 15-60 min. The studies of radical-quenching and electron paramagnetic resonance demonstrated that singlet oxygen (1O2) and superoxide radicals (O2-), rather than sulfate (SO4-) and hydroxyl (OH) radicals, were the dominant species responsible for the oxidation of organic pollutants. The plausible mechanism of the catalytic degradation was proposed and the enhanced activity of Fe3O4@C/PB was assumed to be related to the increased electron transfer owing to the synergic effect between the magnetic carbon and the mixed-valence units in PB. Fe3O4@C/PB is promising in wastewater treatment owing to its high efficiency, excellent stability and reusability, environmental friendliness and magnetic separability.