A γ-Fe2O3-SiO2 composite was prepared by sol-gel method followed by calcination at 700 ℃ for 30 min starting from tetraethoxysilane and iron nitrate.Upon further coating with SiO2 and TiO2,a TiO2/SiO2/（γ-Fe2O3）-S...A γ-Fe2O3-SiO2 composite was prepared by sol-gel method followed by calcination at 700 ℃ for 30 min starting from tetraethoxysilane and iron nitrate.Upon further coating with SiO2 and TiO2,a TiO2/SiO2/（γ-Fe2O3）-SiO2 magnetic photocatalyst was obtained.XRD results show that Fe in the composite converts to the（γ-Fe2O3） phase up to a processing temperature of 700 ℃,and further increase in temperature results in the formation of the（α-Fe2O3） phase.The TiO2/SiO2/（γ-Fe2O3）-SiO2 samples obtained are monodisperse spherical particles with 200～250 nm diameter,well coated firstly by an amorphous SiO2 layer and then by an anatase TiO2 layer.The TiO2/SiO2/（γ-Fe2O3）-SiO2 particles retain their magnetic property well and show high activity for the photocatalytic degradation of salicylhydroxamic acid.展开更多
In this study, pentlandite was selectively separated from serpentine using magnetic coating technology by adjusting and optimizing pH, stirring speeds, magnetic field intensities, and dosages of sodium hexametaphospha...In this study, pentlandite was selectively separated from serpentine using magnetic coating technology by adjusting and optimizing pH, stirring speeds, magnetic field intensities, and dosages of sodium hexametaphosphate(SHMP) and sodium oleate(SO). A magnetic concentrate with Ni grade of 20.8% and Ni recovery of 80.5% was attained under the optimized operating conditions. Considering the above, the adsorption behaviors of SHMP and SO and the surface properties of minerals after the magnetic coating were studied by Fourier transform infrared(FTIR) spectroscopy, X-ray diffraction(XRD), and scanning electron microscopy(SEM). The results show that magnetite was preferentially coated on the pentlandite surfaces and sparingly coated on the serpentine surfaces in the presence of SHMP and SO. Furthermore, calculations by Derjaguin-Landau-Verwey-Overbeek(DLVO) theory indicate that the preferential adsorption of magnetite on the pentlandite surfaces is due to the presence of a hydrophobic interaction between the magnetite and pentlandite, which is much stronger than the interaction between magnetite and serpentine.展开更多
The MnZn ferrite coating formed on the surface of iron-based soft magnetic powders via facile and modified sol–gel process has been fabricated to obtain better magnetic performance due to its higher permeability comp...The MnZn ferrite coating formed on the surface of iron-based soft magnetic powders via facile and modified sol–gel process has been fabricated to obtain better magnetic performance due to its higher permeability compared with traditional nonmagnetic insulation coatings. The influence of the MnZn ferrite contents on the magnetic performance of the soft magnetic composites(SMCs) has been studied. As the MnZn insulation content increases, the core loss first experiences a decreasing trend that is followed by progressive increase, while the permeability follows an increasing trend and subsequently degrades. The optimized magnetic performance is achieved with 2.0 wt% MnZn ferrite, which results from the decrement of inter-particle eddy current losses based on loss separation. A uniform and compact coating layer composed of MnZn ferrite and oxides with an average thickness of 0.38 ± 0.08 μm is obtained by utilizing ion beam technology, and the interface between the powders and the coating shows satisfied adhesiveness compared with the sample directly prepared by mechanical mixing. The evolution of the coating layers during the calcination process has been presented based on careful analysis of the composition and microstructure.展开更多
文摘A γ-Fe2O3-SiO2 composite was prepared by sol-gel method followed by calcination at 700 ℃ for 30 min starting from tetraethoxysilane and iron nitrate.Upon further coating with SiO2 and TiO2,a TiO2/SiO2/（γ-Fe2O3）-SiO2 magnetic photocatalyst was obtained.XRD results show that Fe in the composite converts to the（γ-Fe2O3） phase up to a processing temperature of 700 ℃,and further increase in temperature results in the formation of the（α-Fe2O3） phase.The TiO2/SiO2/（γ-Fe2O3）-SiO2 samples obtained are monodisperse spherical particles with 200～250 nm diameter,well coated firstly by an amorphous SiO2 layer and then by an anatase TiO2 layer.The TiO2/SiO2/（γ-Fe2O3）-SiO2 particles retain their magnetic property well and show high activity for the photocatalytic degradation of salicylhydroxamic acid.
基金financially supported by the National Natural Science Foundation of China(No.51704057)the China Postdoctoral Science Foundation(No.2017M621153)+2 种基金the Postdoctoral Science Foundation of Northeastern University(No.20170312)the Fundamental Research Funds for the Central Universities(No.N170104018)the Open Fund Project of Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources,China(No.2017SKY-WK012)
文摘In this study, pentlandite was selectively separated from serpentine using magnetic coating technology by adjusting and optimizing pH, stirring speeds, magnetic field intensities, and dosages of sodium hexametaphosphate(SHMP) and sodium oleate(SO). A magnetic concentrate with Ni grade of 20.8% and Ni recovery of 80.5% was attained under the optimized operating conditions. Considering the above, the adsorption behaviors of SHMP and SO and the surface properties of minerals after the magnetic coating were studied by Fourier transform infrared(FTIR) spectroscopy, X-ray diffraction(XRD), and scanning electron microscopy(SEM). The results show that magnetite was preferentially coated on the pentlandite surfaces and sparingly coated on the serpentine surfaces in the presence of SHMP and SO. Furthermore, calculations by Derjaguin-Landau-Verwey-Overbeek(DLVO) theory indicate that the preferential adsorption of magnetite on the pentlandite surfaces is due to the presence of a hydrophobic interaction between the magnetite and pentlandite, which is much stronger than the interaction between magnetite and serpentine.
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2018MEM020)
文摘The MnZn ferrite coating formed on the surface of iron-based soft magnetic powders via facile and modified sol–gel process has been fabricated to obtain better magnetic performance due to its higher permeability compared with traditional nonmagnetic insulation coatings. The influence of the MnZn ferrite contents on the magnetic performance of the soft magnetic composites(SMCs) has been studied. As the MnZn insulation content increases, the core loss first experiences a decreasing trend that is followed by progressive increase, while the permeability follows an increasing trend and subsequently degrades. The optimized magnetic performance is achieved with 2.0 wt% MnZn ferrite, which results from the decrement of inter-particle eddy current losses based on loss separation. A uniform and compact coating layer composed of MnZn ferrite and oxides with an average thickness of 0.38 ± 0.08 μm is obtained by utilizing ion beam technology, and the interface between the powders and the coating shows satisfied adhesiveness compared with the sample directly prepared by mechanical mixing. The evolution of the coating layers during the calcination process has been presented based on careful analysis of the composition and microstructure.
