A Novel Fe 3 O 4 @C/RM Composite Fabricated from Red Mud and Scrap Tire-Derived Carbon Black: Heterogeneous Activation of Peroxymonosulfate for Oxidative Degradation of Orange II

This study focuses on preparation of a novel Fe 3 O 4 @C/RM composite by carbothermal reduction of red mud (RM) with scrap tire-derived carbon black and its application for the degradation of orange II in water by activating PMS. X-ray diffraction (XRD) measurements revealed that hematite (Fe 2 O 3 ) was reduced to Fe 3 O 4 in the pyrolysis process above 600 o C. The reduction pathway of Fe 2 O 3 was inferred by detecting the gas emissions during carbothermal reduction. Morphology analysis indicates that Fe 3 O 4 nanoparticles were encapsulated in a carbon matrix, forming a composite with the residual components of RM. The as-prepared Fe 3 O 4 @C/RM composite exhibited high performance toward orange II degradation with 95.9% removal of orange II within 90 min. Electron paramagnetic resonance (EPR) and quenching tests were applied to illustrate the activation processes of peroxymonosulfate. Both radical and non-radical oxygen species are responsible for the efficient degradation of orange II in the Fe 3 O 4 @C/RM/PMS system.