Synthesis of a Fe3O4-rGO-ZnO-catalyzed photo-Fenton system with enhanced photocatalytic performance

In this work, we designed a magnetically-separable Fe₃O₄-rGO-ZnO ternary catalyst, ZnO anchored on the surface of reduced graphene oxide (rGO)-wrapped Fe₃O₄ magnetic nanoparticles, where rGO, as an effective interlayer, can enhance the synergistic effect between ZnO and Fe₃O₄. The effects of three operational parameters, namely irradiation time, hydrogen peroxide dosage, and the catalyst dosage, on the photo-Fenton degradation of methylene blue and methyl orange were investigated. The results showed that the Fe₃O₄-rGO-ZnO had great potential for the destruction of organic compounds from wastewater using the Fenton chemical oxidation method at neutral pH. Repeatability of the photocatalytic activity after 5 cycles showed only a tiny drop in the catalytic efficiency.     

The correlations between structural and optical properties of magnetite nanoparticles synthesised from natural iron sand

The correlations between structural and optical properties of magnetite (Fe₃O₄) nanoparticles were analyzed by using X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. The magnetite was synthesised from the iron sand using NaOH, HCl, and NaCl as a solvent. From the quantitative analysis of XRD spectra, the crystallite size (D), strain ($\epsilon$), stress ($\sigma$), energy deformation (u), porosity, and specific surface area were determined. The Kramers Kronig (K–K) relations was applied to the FTIR spectra to determine the optical properties: refractive index (n), extinction coefficient (k), the complex dielectric function ($\mathit{\epsilon }$), and the energy loss function (Im(-1/ε)). The uniform strain was produced from the NaOH and HCl as the solvent. The magnetite had higher porosity with NaCl as a solvent and was directly proportional to the optical phonon vibration. We found a perfect correlation; when the difference between two optical phonon increases, the crystallite size decreases, and the strain will be uniform.     

弱磁精选设备在磁铁矿降硅提铁中的研究与实践

阐述了弱磁精选设备对磁铁矿降硅提铁技术研究及应用的意义，指出弱磁场磁选设备若可以达到降硅提铁目的，磁选工艺应是首选方法。分析了常规磁选设备用于降硅提铁分选精度不高的原因，介绍了弱磁场降硅提铁磁选设备的研究及应用现状。生产实践表明，磁聚机和磁选柱用于磁铁矿降硅提铁效果明显。     

Magnetically controlled shape-memory effects of hybrid nanocomposites from oligo(ω-pentadecalactone) and covalently integrated magnetite nanoparticles

The covalent integration of inorganic nanoparticles in polymer matrices has gained significance for improving the structural properties of polymer-based materials. Here we report on the performance of poly(ω-pentadecalactone) networks with magnetite nanoparticles as netpoints in their magnetically-controlled shape-memory capability. Hybrid nanocomposites with magnetite nanoparticle content ranging from 5 to 11 wt% were prepared by reacting two types of oligo(ω-pentadecalactone) (OPDL) based precursors with terminal hydroxy groups, a three arm OPDL (³AOPDL, M_n = 6000 g mol⁻¹) and an OPDL (M_n = 3300 g mol⁻¹) coated magnetite nanoparticle (∅ = 10 nm), with a diisocyanate. Homogenous hybrid nanocomposites were obtained independent from the weight content of the OPDL decorated nanoparticles in the samples. At 100 °C (T > T_m-OPDL) the covalent integration of the nanoparticles increased the mechanical strength with increasing weight content whereby the elasticity remained almost constant. In magnetically-controlled one-way dual-shape experiments the shape fixity decreased from 95% to 90% but the shape recovery increased slightly from 95% to 97% when the nanoparticle content was increased. In magnetically-controlled reversible dual-shape experiments the nanoparticles had a restraining effect and the maximum shape-change of 65% for hybrid nanocomposites with 5 wt% magnetite nanoparticles was reduced to 36% when the particle content was increased to 11 wt%. These results show that the performance of hybrid nanocomposites can be tailored by nanoparticle content, however in terms of their applicability either mechanical strength or actuation capability should be focussed in the material selection.     

Study on surface magnetization recover ilmenite from titanaugite using surfactant sodium oleate

ABSTRACT

Separation of ilmenite from titanaugite was investigated by magnetic coating. By enlarging magnetic difference between ilmenite and titanaugite, ilmenite was efficiently recovered. Scanning electron microscope and vibrating sample magnetometer results indicated that magnetite selectively coated onto ilmenite surface and increased its magnetism, which resulted in different magnetic separation behavior between ilmenite and titanaugite. FTIR and contact angle measurements confirmed that the adsorption difference of sodium oleate resulted in a stronger hydrophobicity on magnetite and ilmenite than titanaugite. Interaction energy analysis illustrated that hydrophobic association interaction on ilmenite was stronger than that on titanaugite, and which led to the selective coating of magnetite onto ilmenite.     

新型捕收剂对赤铁矿捕收性能的研究

介绍了新型铁矿物捕收剂ＲＣ９５０２用于浮选包钢选厂一、三系列强磁铁精矿（α４０．０３％ＳＰｃ）中的有用铁矿物试验，经一次反浮、正浮、一次精选可使精矿品位提高到６３．９１％ＳＦｅ，回收率为６７．４４％，ＦＣ９５０２能有效地捕收赤褐铁矿和磁铁矿，与用氧化石腊皂作捕收剂比较，不仅能获得更好的选别指标，而且可降低捕收剂成本约３０％．     

Hierarchically nanostructured Fe3O4 microspheres and their novel microwave electromagnetic properties

Magnetite nanoparticles are found to assemble into monodisperse Fe₃O₄ microspheres with diameters ∼ 300 nm and open pores on the shells in ethylene glycol (EG) in the presence of polyethylene 2000 (PEG 2000) and a small quantity of polyethyleneimine (PEI). The hysteresis loops of the magnetic microspheres are measured by a vibrating sample magnetometer (VSM), the ferromagnetic signature emerged with the saturated magnetization of ∼ 80.0 emu g^− 1, and the coercive force of ∼ 208.7 Oe. The synthesized hierarchical microspheres exhibit two microwave magnetic loss peaks: one appears at 4.0-5.0 GHz, the other appears around 16.0-17.0 GHz. The latter peak is attributed to the effect of the morphology of the hierarchical structure. Modern analysis methods SEM, TEM, XRD etc., are employed to figure the detailed structure information of the magnetic hollow spheres.     

Structural alterations during mechanochemical activation of a titanium–magnetite mixture

In this work, mechanochemical activation and thermal behaviour of (Ti + Fe₃O₄) mixtures in Ti/Fe₃O₄ molar ratios 0.5, 1, and 1.5, are studied. The samples were activated under Ar atmosphere, thermally treated at temperatures ranging between 400 and 700 °C, and analyzed by XRD and Rietveld analysis, SEM and EPMA. By XRD, a progressive decrease in crystallinity with the activation time of was observed. For the samples with lower Ti contents, the system evolved towards the formation of a ulvospinel (Fe₂TiO₄)–magnetite (Fe₃O₄) solid solution, while for higher Ti contents the major phase obtained was ilmenite (FeTiO₃). During the activation at room temperature, low crystalline intermediate phases (FeO + TiO, FeO, pseudobrookite [Fe₂TiO₅]) were generated, depending on the initial mixture composition. Thermal treatments resulted in a progressive structural ordering, with lattice parameters slightly greater than those of the original spinel.These results suggest that during the activation at room temperature, the Ti reduces the Fe of the spinel and partially replaces it in the lattice.     

庙沟铁矿选矿流程优化的初步探讨

由于原矿性质发生变化，庙沟铁矿现行选矿工艺流程已不能完全适应生产需要，主要表现为：精矿品位达不到要求，二次细筛效率低，磁铁矿反富集严重。作者提出了采用粒度分级工艺对流程进行优化的措施。     

Influence of Co content on the characterization and magnetic properties of magnetite

Preparation of nanosized Co_xFe_3−xO₄; 0.05 ≤ x ≤ 0.20 particles from metal nitrates solution through citrate–precursor method was performed. XRD pattern of all prepared systems showed single phase with cubic spinel structure. The crystallite size was determined from TEM and found to agree with that calculated from Sherrer's equation (60–76 nm) The magnetic constants such as molar magnetic susceptibility (χ_M), Curie temperature (T_C) and saturation magnetization (M_S) were measured and the results indicated that, at x = 0.2 the values of χ_M, M_S, remanent magnetization (M_r,) and coercive field (H_c) are 23 emu/g mol, 77.62 emu/g, 33.17 emu/g and 574.5 Oe, respectively_.