Synthesis of magnetic core-shell Fe3O4@TiO2 nanoparticles from electric arc furnace dust for photocatalytic degradation of steel mill wastewater

The study was undertaken to design magnetic core-shell Fe3O4@TiO2 nanoparticles fromelectric arc furnace dust and evaluate its photocatalytic activity on organic pollutant degradation from steel industry wastewater. Different molar ratios of Fe3O4 to TiO2 were tested on Fe3O4@TiO2 nanoparticles. The materials were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform-infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy, and a zeta potential analyzer and vibrating sample magnetometer. The behavior of Fe3O4@TiO2 nanoparticles under different molar ratios of Fe3O4 to TiO2, pH, photocatalyst dose and temperature was investigated. The apparent rate constant of organic pollutant degradation using Fe3O4@TiO2 was found to be pH dependent as it influenced the surface properties and therefore the photocatalytic activity of Fe3O4@TiO2, which was higher under acidic condition. The degradation of organic pollutants was as high as 96% at pH 3, 1 g L-1 photocatalyst dose, 30 degrees C temperature, after 90 min reaction time, and the apparent rate constant was 0.043 min(-1). The thermodynamic parameters of activation, estimated by the Eyring equation and based on transition state theory (TST), indicated a nonspontaneous process in nature with positive Delta(double dagger)G(o) values, an endothermic reaction with positive Delta H-double dagger(o) and negative Delta S-double dagger(o) values. High degradation rate and catalyst recovery were maintained after five consecutive recycling cycles.