Fenton-like catalyst Fe3O4@polydopamine-MnO2 for enhancing removal of methylene blue in wastewater

• A novel Fenton-like catalyst Fe 3 O 4 @PDA-MnO 2 was facilely synthesized. • This catalyst was applied in pH ranging from 2 to 12 in Fenton systems. • Fe 3 O 4 @PDA-MnO 2 retained excellent reusability after 5 using-cycles. • The mechanism of Fe 3 O 4 @PDA-MnO 2 removing methylene blue was proposed. • Fe 3 O 4 @PDA-MnO 2 had good catalytic performance in practical application. Fenton technology has been proven an effective way to remove dyes from wastewater. However, the demanding pH of reaction condition restricted its wide application. In this study, we report a novel Fenton-like catalyst (Fe 3 O 4 @PDA-MnO 2 ) facilely synthesized by polydopamine (PDA) coating and MnO 2 depositing onto the surface of Fe 3 O 4 nanoparticles. This method for preparing magnetic Fe 3 O 4 @PDA-MnO 2 catalyst could avoid the agglomeration of MnO 2 nanoparticles and make the catalyst collect easily from the solution. The resultant Fe 3 O 4 @PDA-MnO 2 nanoparticles possess core-shell nanostructure. Fe 3 O 4 @PDA-MnO 2 catalyst could cooperate with hydrogen peroxide to form a Fenton-like reagent for the removal of methylene blue (MB) and performed excellent catalytic activities towards MB, including high degradation efficiency of 97.36% after 240 min. Besides, Fe 3 O 4 @PDA-MnO 2 can retain excellent reusability after 5 using-cycles. More importantly, the catalyst can be used in a wide pH range from 2 to 12 in Fenton systems, demonstrating that the degradation process is independent on pH which is different from most reported studies. Also, Fe 3 O 4 @PDA-MnO 2 could still keep more than 75% removal efficiency of MB in industrial wastewater treatment application. Therefore, the synthesized Fe 3 O 4 @PDA-MnO 2 would be a promising device for the removal of dyes from wastewater.