The magnetic photocatalyst Fe3O4/SiO2/ZnO was synthesized by sol-gel method. For this purpose, in the first stage, Fe3O4 particles were prepared as the magnetic core of this composite and using the carbon recovery method. In the second stage, the coating of the SiO2 shell was performed using the tetraethyl orthosilicate (TEOS) precursor. In the end, the zinc oxide shell was deposited using a zinc hydrate nitrate precursor on the Fe3O4/SiO2 composite. The as-prepared nanostructures were characterized by environmental scanning electron microscopy analysis (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Vibrating Sample Magnetometer (VSM) and Energy Dispersive X-ray (EDX). FESEM and TEM results confirmed the coating of silica and zinc oxide on core particles and the Fe3O4/SiO2/ZnO magnetic photocatalyst was successfully prepared. The particle size mean of Fe3O4 was 300 nm approximately. The silica shell thickness was 25 nm, and the thickness of the zinc oxide shell was about a few nanometers approximately. The VSM results showed that coating of silica and zinc oxide shells reduced the saturation magnetization (Ms) of Fe3O4 powder so that the saturation magnetization decreased from 80/8 emu/g to 48/8 emu/g, which It is suitable for Magnetic Recovery. Photocatalytic properties of Fe3O4/SiO2/ZnO composite were studied on methylene orange degradation under UV light irradiation. Destruction of orange methylene was achieved 70%.

The magnetic photocatalyst Fe3O4/SiO2/ZnO was synthesized by sol-gel method. For this purpose, in the first stage, Fe3O4 particles were prepared as the magnetic core of this composite and using the carbon recovery method. In the second stage, the coating of the SiO2 shell was performed using the tetraethyl orthosilicate (TEOS) precursor. In the end, the zinc oxide shell was deposited using a zinc hydrate nitrate precursor on the Fe3O4/SiO2 composite. The as-prepared nanostructures were characterized by environmental scanning electron microscopy analysis (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Vibrating Sample Magnetometer (VSM) and Energy Dispersive X-ray (EDX). FESEM and TEM results confirmed the coating of silica and zinc oxide on core particles and the Fe3O4/SiO2/ZnO magnetic photocatalyst was successfully prepared. The particle size mean of Fe3O4 was 300 nm approximately. The silica shell thickness was 25 nm, and the thickness of the zinc oxide shell was about a few nanometers approximately. The VSM results showed that coating of silica and zinc oxide shells reduced the saturation magnetization (Ms) of Fe3O4 powder so that the saturation magnetization decreased from 80.8 emu/g to 48.8 emu/g, which It is suitable for Magnetic Recovery. Photocatalytic properties of Fe3O4/SiO2/ZnO composite were studied on methylene orange degradation under UV light irradiation. Destruction of orange methylene was achieved 70%.

In this research study, the coating of titania particles on the SrFe12O19/SiO2 composite was successfully accomplished by the sol-gel process. For this purpose, first, the strontium hexaferrite particles were prepared by co-precipitation route with Fe3+/Sr2+ molar ratios of 11 and 12 and subsequent calcination treatment. The formation of single phase strontium hexaferrite particles, as hard magnetic cores of the composite, was attained in the molar ratio of Fe3+/Sr2+=12 after calcination at 950 ° C. In the next step, the silica coating of hexaferrite particles was performed using the tetraethyl orthosilicate (TEOS) precursor via the Stö ber method. In the end, the covering of titania particles on the SrFe12O19/SiO2 composite was carried out by utilizing titanium n-butoxide (TNBT) precursor. The as-prepared composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and vibrating sample magnetometry (VSM) analyses. The results confirmed the core/shell/shell structure of the synthesized SrFe12O19/SiO2/TiO2 composite. The analysis of the magnetic properties showed that saturation magnetization (Ms) of strontium hexaferrite powder was obtained as 58 emu/g. After the successive coating of SiO2 and TiO2 shells, this amount has reached to 56 emu/g and 37 emu/g, respectively.

Fe3O4 nanoparticles (NPs) with a continuous and mesoporous silica (m-SiO2) shell were synthesized using a one-step method, sourcing silica from rice husk ash (RHA). The rice husk was thermally treated to obtain ash, from which silica was extracted as sodium silicate and precipitated by pH reduction. This silica powder, combined with iron chloride salts, facilitated the synthesis of the core-shell NPs. Mint extract acted as a capping agent to prevent agglomeration, and CTAB (cetyltrimethylammonium bromide) was used to create the porous SiO2 shell. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) characterization investigated the structure, size, and shell formation. Coating integrity and suspension stability were assessed through Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS). DLS analysis showed a relatively narrow particle size distribution with an average hydrodynamic size of 72.6 nm. Small-angle X-ray scattering (SAXS) provided insights into the meso- and nanoscale structure, while BET and nitrogen adsorption-desorption isotherms confirmed the mesoporous nature of the silica shell. Magnetization measurements showed superparamagnetic behavior, with specific magnetization values of 57.9 emu/g for Fe3O4 and 27.5 emu/g for Fe3O4@m-SiO2. These results confirm the successful synthesis of superparamagnetic magnetite NPs with a mesoporous silica coating from RHA.

In this research, the thermal buckling analysis of a truncated conical shell made of porous materials on elastic foundation is investigated. The equilibrium equations and the conical shell`s stability equations are obtained by using the Euler`s and the Trefftz equations. Properties of the materials used in the conical shell are considered as porous foam made of steel, which is characterized by its non-uniform distribution of porous materials along the thickness direction. Initially, the displacement field relation based on the classical model for double-curved shell is expressed in terms of the Donnell`s assumptions. Non-linear straindisplacement relations are obtained according to the von Ká rmá n assumptions by applying the Green-Lagrange strain relationship. Then, performing the Euler equations leads obtaining nonlinear equilibrium equations of cylindrical shell. The stability equations of conical shell are obtained based on neighboring equilibrium benchmark (adjacent state). In order to solve the stability equations, primarily, due to the existence of axial symmetry, we consider the cone crust displacement as a sinusoidal geometry, and then, using the generalized differential quadrature method, we solve them to obtain the critical temperature values of the buckling Future. In order to validate the results, they compare with the results of other published articles. At the end of the experiment, various parameters such as dimensions, boundary conditions, cone angle, porosity parameter and elastic bed coefficients are investigated on the critical temperature of the buckling.