Preparing carbon-black-coated magnetite nanoparticles: fabrication, characterization, and heterogeneous persulfate oxidation of methylene blue

摘要

The aim of this study was persulfate (PS) oxidation of methylene blue (MB) using iron oxide-carbon black (Fe3O4-CB) as heterogeneous catalyst in aqueous solution. The oxidation reaction was optimized based on enlisted factors: the initial pH, PS concentration, and Fe3O4-CB amount. The degradation kinetics and reactivity of the catalyst were also investigated. The decolorization rate of MB showed strong pH dependence. The degradation process followed the pseudo-first-order kinetic model. The catalyst were characterized by using X-ray diffraction (XRD), a superconducting quantum interference device magnetometry, fluorescence spectroscopy, ultraviolet-visible spectroscopy, cyclic voltammetry (CV), Brunauer-Emmett-Teller analysis, and environmental scanning electron microscopy (ESEM). XRD analysis indicated the existence of Fe3O4 on the composite surface. The magnetic properties of Fe3O4-CB showed great saturation magnetization (Ms). The CV reversible redox ability explained the high activity of the Fe3O4-CB composite, and the oxidation current density on the Fe3O4-CB composite increased with the scan rate. ESEMEDS measurements revealed the presence of Fe3O4 crystal nanoparticles on the CB-supported surface and resulting in higher surface area up to 1,965 m g(-1). These spherical crystal phases dispersed in the CB matrix with sizes of 50-100 nm may explain the high activity of the composite in heterogeneous SO4-center dot-based advanced oxidation process reaction, which is also responsible for the strong metal-support interaction.