Controllable Preparation and Catalytic Performance of Heterogeneous Fenton-like α-Fe2O3/Crystalline Glass Microsphere Catalysts

Highly dispersed α-Fe 2 O 3 nanoparticles were immobilized onto crystalline glass microspheres for the first time to be heterogeneous Fenton catalysts (FeCG) with favorable activity. The average particle size of the supported iron oxides ranges from 2.6 to 6.5 nm and can be achieved controllably with great ease. Typically, through hydrothermal treatment, it was found that an amorphous glass support develops into mixed crystals of primitive SiO 2, CaSi 2 O 5, and Ca 2 MgSi 2 O 7, with ∼180% improvement in specific surface areas. Most importantly, after Fe loading, not only OH· but also HO 2 · radical species with high intensity were generated for FeCG, while OH· alone was produced for commercial α-Fe 2 O 3 in the presence of H 2 O 2, thus accelerating the redox recycling between Fe(II) and Fe(III) and presenting much superiority in the azo dye AO7 decoloration. The pseudo-zero-order reaction constant was determined to be 0.384 mg/(L·min), an ∼65.5% improvement over that of commercial α-Fe 2 O 3 under the same experimental conditions. Only 1.26 mg/L Fe leaching was detected under optimum conditions in addition to simple catalyst recovery by gravity. No remarkable decrease in the AO7 decoloration efficiency was observed after six cycles, indicating the favorable stability.