Synergetic activation of peroxymonosulfate by MnO-loaded β-FeOOH catalyst for enhanced degradation of organic pollutant in water.

In this paper, manganese dioxide (MnO) loaded iron oxyhydroxide (β-FeOOH) was synthesized aiming to improve the catalytic performance of β-FeOOH as peroxymonosulfate activator. The β-FeOOH@MnO/PMS system exhibited excellent performance and its reaction rate constant of Acid Orange 7 (AO7) degradation (0.0533 min) was approximately 2.3 times as that in β-FeOOH/PMS system (0.0232 min). β-FeOOH@MnO possessed superior properties as catalyst than β-FeOOH, owing to the higher surface hydroxyl density with higher specific surface area, redox ability and electronic transmission rate. Moreover, on the basis of the analysis from FTIR and XPS, it was found that the redox reaction of Fe/Fe and Mn/Mn synergistically activated PMS as well as the generation of FeOH and MnOH accelerated activating PMS in the β-FeOOH@MnO/PMS system. Thus, MnO and FeOOH synergistically activated PMS to reactive oxygen species (ROS). And O, O and OH were identified as predominant ROS in the β-FeOOH@MnO/PMS system on the basis of the result from quenching experiments and ESR. As a result, TOC removal rate was increased up to 22.62%. Additionally, β-FeOOH@MnO exhibited good stability with low iron dissolution and manganese dissolution. Generally, this study proposed that β-FeOOH@MnO was an efficient and environmental catalyst as PMS activator for organic pollutant degradation in water.