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

Abstract

The study was undertaken to design magnetic core-shell Fe 3 O 4 @TiO 2 nanoparticles from electric arc furnace dust and evaluate its photocatalytic activity on organic pollutant degradation from steel industry wastewater.Different molar ratios of Fe 3 O 4 to TiO 2 were tested on Fe 3 O 4 @TiO 2 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 Fe 3 O 4 @TiO 2 nanoparticles under different molar ratios of Fe 3 O 4 to TiO 2 , pH, photocatalyst dose and temperature was investigated. The apparent rate constant of organic pollutant degradation using Fe 3 O 4 @TiO 2 was found to be pH dependent as it influenced the surface properties and therefore the photocatalytic activity of Fe 3 O 4 @TiO 2 , which was higher under acidic condition. The degradation of organic pollutants was as high as 96% at pH 3, 1 g L À1 photocatalyst dose, 30 C temperature, after 90 min reaction time, and the apparent rate constant was 0.043 min À1 . 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 D ‡ G o values, an endothermic reaction with positive D ‡ H o and negative D ‡ S o values. High degradation rate and catalyst recovery were maintained after five consecutive recycling cycles.

Design and Application of Magnetic Photocatalysts for Water Treatment. The Effect of Particle Charge on Surface Functionality

“…According to the TEM image of core-interlayer-shell Fe 3 O 4 /SiO 2 /TiO 2 nanoparticle the dark and bright regions correspond to the Fe 3 O 4 and the shell, respectively. The magnetic core is identified as the darker region compared to the non-magnetic SiO 2 and TiO 2 shell area due to their different electron-absorbing abilities [28]. The core-interlayer-shell structure of Fe 3 O 4 coated with SiO 2 and TiO 2 was confirmed by EDXS mapping, presented in Figure 5b.…”

“…Therefore, the lower photocatalytic activity of BaFe 12 O 19 /SiO 2 /TiO 2 _2 nanocomposite results from the properties of the photocatalytic layer instead of the magnetic core behavior. Salamat et al [28] reported that the variations in the photocatalytic activity of TiO 2 /SiO 2 deposited on Fe 3 O 4 are related to the effect of change in the molar ratio of Ti and Si to Fe 3 O 4 . Therefore, it can be assumed that the amount of silica and titania deposited on the surface of the ferrite core should be determined depending on the ferrite core particles size and shape.…”

“…Phenol was not degraded in the absence of illumination, indicating that there was no dark reaction at the surface of self-prepared nanocomposites. The functionalization of the magnetic core with silica interlayer and a layer of commercial TiO 2 P25 results in higher photocatalytic performance, as shown in Figure 9 [28]. Therefore, it can be assumed that photocatalytic and magnetic properties can be manufactured by appropriately adjusting the reaction condition during formation of the semiconductor shell.…”

“…of irradiation about 80% and 27% of phenol was degraded and mineralization was 52% and 15% for CoFe2O4/SiO2/TiO2_1 and BaFe12O19/SiO2/TiO2_2, respectively. Salamat et al reported that the variations in the photocatalytic activity of TiO2/SiO2 deposited on Fe3O4 are probably related to the effect of change in the molar ratio of Ti and Si to Fe3O4 [28]. Therefore, it can be assumed that photocatalytic and magnetic properties …”

Recyclable Magnetic Titania Nanocomposite from Ilmenite with Enhanced Photocatalytic Activity

“…Recently, magnetic titania has gained increasing attention, as it has the advantages of magnetic recovery and excellent photocatalytic properties [15,16,17,18,19]. They can achieve the fast separation and easy recovery of nano-TiO 2 by external magnetic fields, thus preventing the loss of active components and improving the durability of catalysts.…”