Synergetic activation of peroxymonosulfate by MnO2-loaded β-FeOOH catalyst for enhanced degradation of organic pollutant in water

In this paper, manganese dioxide (MnO 2 ) loaded iron oxyhydroxide (β-FeOOH) was synthesized aiming to improve the catalytic performance of β-FeOOH as peroxymonosulfate activator. The β-FeOOH@MnO 2 /PMS system exhibited excellent performance and its reaction rate constant of Acid Orange 7 (AO7) degradation (0.0533 min −1 ) was approximately 2.3 times as that in β-FeOOH/PMS system (0.0232 min −1 ). β-FeOOH@MnO 2 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 3+ /Fe 2+ and Mn 4+ /Mn 3+ synergistically activated PMS as well as the generation of FeOH + and MnOH 2+ accelerated activating PMS in the β-FeOOH@MnO 2 /PMS system. Thus, MnO 2 and FeOOH synergistically activated PMS to reactive oxygen species (ROS). And 1 O 2 , O 2 − and OH were identified as predominant ROS in the β-FeOOH@MnO 2 /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 2 exhibited good stability with low iron dissolution and manganese dissolution. Generally, this study proposed that β-FeOOH@MnO 2 was an efficient and environmental catalyst as PMS activator for organic pollutant degradation in water.