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The amounts of large-tonnage mineral waste that are generated raise serious misgivings at environmental protection agencies. Most mineral waste is a valuable secondary raw material, but the lack of integrated technologies for their processing substantially slows down their processing. An assessment was made of the possibility of joint processing of quartz-leucoxene concentrate (waste from oil extraction) and brucite-containing waste from the production of refractories. Joint pyrometallurgical processing of two wastes made it possible to obtain magnesium titanate, a valuable product for different industries. In hydrometallurgical processing of magnesium titanate, a complex magnesium-titanium containing coagulant was obtained, which showed high efficiency in the process of treating high-pH wastewater (concrete mixing unit). In addition to increasing the purification efficiency (reducing the residual concentrations of pollutants), the use of a complex reagent made it possible to reduce reagent costs and intensify the sedimentation and filtration of coagulation sludge (simplification of the instrumentation). [ABSTRACT FROM AUTHOR]

A series of NIR-reflective brownish orange pigments comprising various amounts of Fe2O3 have been synthesized by a conventional solid-state reaction at 1100 °C. Magnesium titanate base pigment was synthesized from MgO and leucoxene mineral which was employed as TiO2 source. The resultant pigment had brownish gray appearance (L*a*b* = 68.67, 7.83, 18.68, respectively) and NIR reflectance of 81.0%. Incorporating the magnesium titanate pigment with various amounts of Fe2O3 (molar ratio (x) = 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) resulted in a change of color hue to brownish orange, and a change of NIR reflectance from 81.0 to 41.1% upon the increase of Fe2O3 content. Optical bang-gap energies derived from diffused reflectance spectra reduced from 2.75 eV for the magnesium titanate to 2.25, 2.20, 2.10, 1.90, 1.70 and 1.60 eV for pigments incorporated with 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0 mole Fe2O3, respectively. At the optimum synthesis condition (x = 0.3), the pigment exhibited light brownish orange color hue (L*a*b* = 52.02, 23.94, 39.37) and NIR reflectance of 80.1%. An accelerated QUV weathering test according to the ASTM G154-16 standard revealed color fading (ΔE*) of only 0.95 indicating excellent weathering stability. [ABSTRACT FROM AUTHOR]

In this study, magnesium titanate was prepared through the high-temperature reaction of ilmenite and MgO in a reducing atmosphere, and its formation process and mechanism under different conditions were investigated. The results showed that a reducing atmosphere is necessary to prepare magnesium titanate. Although Mg could replace Fe and form magnesium titanate without reductant, the generated magnesium titanate contained large amounts of iron. While a reducing atmosphere promoted the formation of magnesium titanate and accelerated the reaction rate, this is because iron oxide in the reaction system is reduced to metal Fe under a reducing atmosphere. The effect of iron reduction improved, the content of iron in the magnesium titanate decreased with increasing temperature, and pure particles of magnesium titanate were generated at 1450°C. Magnesium titanate was transformed along MgTi2O5→MgTiO3→Mg2TiO4 path with increasing MgO dosage. The magnesium titanate product, contains above 90% Mg2TiO4, was obtained by grinding and magnetic separation as non-magnetic product. [ABSTRACT FROM AUTHOR]

Magnesium titanate was prepared directly through external coal reduction of seashore titanomagnetite concentrate and magnesium oxide (MgO). The effects of roasting temperature and the type and dosage of reductants on the purity of generated magnesium titanate particles were systematically investigated. Scanning electron microscopy and energy-dispersive spectroscopy analyses were performed to characterize the magnesium titanate particles and observe their purity under different conditions. Results showed that the roasting temperature remarkably influenced the purity of magnesium titanate. At 1200, 1300, and 1400°C, some magnesium ferrite and magnesium aluminate spinel were dissolved in magnesium titanate. However, as the roasting temperature increased to 1500°C, relatively pure magnesium titanate particles were generated because no magnesium ferrite was dissolved in them. The type and dosage of the reductants also remarkably affected the purity of magnesium titanate. The amount of fine metallic iron disseminated in the magnesium titanate particles obviously decreased when lignite was used as a reductant at a dosage of 70wt%. Thus, high-purity magnesium titanate particles formed. At a roasting temperature of 1500°C and with 70wt% lignite, the magnesium titanate product with a yield of 30.63% and an iron content of 3.01wt% was obtained through magnetic separation. [ABSTRACT FROM AUTHOR]

Effect of temperature and Mg:Ti ratio on phase composition and microstructure of reduced pellets was investigated to verify the feasibility of preparation of magnesium titanate by adding MgO in carbonthermic reduction of the vanadium titanomagnetite concentrates (VTC). Thermodynamic analysis results showed that magnesium titanate is more easily generated than FeTi2O5 or TiO2 by the reaction of FeTiO3 and MgO under the reductive atmosphere, which was confirmed by the discovery of magnesium titanate at roast experiment. It was found that the optimum conditions for reduction of VTC pellets were temperature of 1250 ºC and Mg:Ti ratio of 2, and the main phases of reduction product were metallic Fe and magnesium titanate (Mg2TiO4). However, trace iron impurities in Mg2TiO4 particles were found by energy-dispersive spectroscopy (EDS), so further purification is required. [ABSTRACT FROM AUTHOR]

Nanoparticles with different morphology have been obtained by hydrothermal method in the system MgO-SiO-TiO-HO. It has been found that in the investigated temperature-time interval the formation of nanotubes of hydrosilicate with the structure of chrysotile with a small amount of impurity phases predominantly takes place. [ABSTRACT FROM AUTHOR]

Degradation of 2-chloroethyl ethyl sulfide (2-CEES), a stimulant of sulfur mustard, was investigated on the surface of polyacrylonitrile (PAN) nanofibres embedded with magnesium aluminate and magnesium titanate nanoparticles. The magnesium aluminate and magnesium titanate nanoparticles were prepared by the hydrothermal method and characterized by X-ray diffractometry, scanning electron microscopy and nitrogen adsorption BET. These metal oxide nanoparticles were mixed with PAN solution individually and then electrospun to produce nanofibres. Later, they were studied against the degradation of 2-CEES at room temperature (30±2 °C) using gas-chromatography coupled with flame ionization detector. The degradation and reaction kinetics data reveal that the 2-CEES degraded faster with higher amount of embedded metal oxide nanoparticles in PAN nanofibres. Moreover, the degradation yield of 2-CEES was higher in the case of PAN nanofibres embedded with magnesium aluminate nanoparticles relative to PAN nanofibres embedded with magnesium titanate nanoparticles. Fourier-transform infrared (FTIR) studies showed that the PAN nanofibres embedded with magnesium aluminate and magnesium titanate nanoparticles degrade 2-CEES by the formation of covalent/alkoxide bonds between the surface reactive oxide/hydroxyl group of metal oxide nanoparticles and 2-CEES. The result explores the role of modified PAN nanofibres with magnesium aluminate on the effective degradation of 2-CEES and possesses a suitable candidate for protective application. [ABSTRACT FROM AUTHOR]

The morphological manipulation and structural characterisation of TiO-MgO binary system by an aqueous particulate sol-gel route were reported. Different crystal structures including pure MgTiO, mixtures of MgTiO and TiO and mixtures of MgTiO and MgTiO were tailored by controlling Mg:Ti molar ratio and annealing temperatures as the processing parameters. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that all compounds crystallised at the low temperature of 500 °C. Furthermore, it was found that the average crystallite size of the compounds depends upon the Mg:Ti molar ratio as well as the annealing temperature, being in the range 3-5 nm at 500 °C and around 6 nm at 700 °C. Field emission scanning electron microscope (FE-SEM) analysis revealed that the deposited thin films had nanocrystalline structure with the average grain size of 25-30 nm at 500 °C depending upon the Mg:Ti molar ratio. Moreover, atomic force microscope (AFM) images presented that the thin films had a hill-valley like morphology made up of small grains. [ABSTRACT FROM AUTHOR]

A series of AlMCM-41 molecular sieves were synthesized starting from a hydrogel keeping the following molar composition: 1CTMABr:4.58SiO2:(0.437+X)Na2O:XAl2O3:200H2O. Tetramethylammonium silicate (TMAS) was used as silicon source and cethyltrimethylammonium bromide (CTMABr) was used as structure template. The obtained materials were characterized by nitrogen adsorption, XRD and TG/DTG. Acid properties were determined by pyridine thermodesorption. Model-free and Flynn-Wall kinetic models were used in order to correlate the total acidity with the apparent activation energy of pyridine desorption. [ABSTRACT FROM AUTHOR]

We have studied the application of magnesium titanate thin films as buffer layer for the improvement of adhesion of Pt films to Si substrate. Magnesium titanate films were successfully prepared on Si(100) substrate by electron beam evaporation. The crystal phase of MgTi 2 O 5 and MgTiO 3 films on Si substrate were observed. These films had a very smooth and densely packed surface morphology and showed a good characteristic as the adhesion layer for Pt. Also, AES analysis showed the excellent properties as the reaction barrier layer between Pt and Si. [ABSTRACT FROM AUTHOR]

This review deals with the solution-sol-gel processing (SSG) of powders such as BaTiO3, MgTiO3, PbTiO3, Bi4Ti3O12, La2Ti2O7, Pb(Zr0.52Ti0.48)O3, Pb(Mg1/3Nb2/3)O3 and Ba(Mg1/3Ta2/3)O3. Fine powders of good sinterability can be easily obtained at low temperatures although the process can be expensive and time consuming. We propose a nanocomposite route which utilizes nanophases of different components as a cost-effective alternative to sol-gel process for powder preparation. [ABSTRACT FROM AUTHOR]

The interaction between magnesium and titanium alkoxides is studied in order to chose the best precursors for synthesis of MgTiO3. No reaction between magnesium and titanium methoxides and isopropoxides occurs. The solubility diagrams for Mg(OR)2-Ti(OR)4-ROH, R = Et,-Bu at 20°C are studied. Magnesium ethoxotitanates of variable composition MgnTi4-n (OEt)16-2nċ2nEtOH (n=2.0-0) which are structural analogs of Ti4(OR)16 (R = Me, Et) are isolated. This is a quite unusual example of statistical distribution of heteroatoms in molecular structures of metal alkoxides. Among the systems of metal alkoxides with simple aliphatic radicals only Mg(OBu)2-Ti(OBu)4-BuOH gives a convenient precursor for the synthesis of MgTiO3. A simple scheme of preparation of magnesium titanate from the alkoxide solutions is suggested. The phase purity of MgTiO3 is to a considerable extent dependent on the hydrolysis conditions. The alkoxy-derived magnesium titanate is obtained in the form of a uniform fine powder, it can be sintered into dense ceramics in the temperature range of 1140–1220°C which is 150–200°C lower in comparison with the conventional powders. [ABSTRACT FROM AUTHOR]