Investigation of dye removal properties of manganese oxide based magnetic microspheres in aqueous medium

In this study, monodisperse and porous MagMn5O8 microspheres were synthesized via a multi-step solvothermal method using polymer mold material for removal of Rhodamine B (RhB) from aqueous solutions. The surface and bulk compositions of MagMn5O8 microspheres was analyzed using X-Ray Photoelectron Spectroscopy (XPS) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), and their morphological properties were determined using BET analysis and Scanning Electron Microscopy (SEM). The magnetic characterization was done using Vibrating Sample Magnetometer (VSM), and their crystal structure was examined using X-Ray Diffraction (XRD). MagMn5O8 micropheres were used as a heterogeneous catalyst in the activation of peroxymonosulfate (PMS). The reactive oxygen species (ROS) produced by PMS reacted with RhB are responsible for the degradation of RhB in the aqueous medium. The decrease in RhB concentration was explained by ROS related reactions. The removal reaction was significantly accelerated by the heterogeneous catalyst and almost quantitative RhB removals were achieved in a short time. Electron Spin Resonance (ESR) analysis provided the signals indicating DMPO-1O2 radical with an intensity of 1:1:1 and AN of 14.9 G, and DMPO-OOH radical with an intensity of 1:2:2:1 and AN of 15.3 G. The ESR analysis and radical scavenging experiments showed that 1O2 and O2- radicals in MagMn5O8-PMS system are responsible for -chemical degradation of RhB. The monodisperse-porous MagMn5O8 microspheres was used as an efficient and reusable heterogeneous catalyst for the degradation of a dye which was resistant to decomposition in the aqueous medium.