MgO Components Research Articles

Formation features of MgO–Y2O3 nanocomposite of complex shape through aqueous slip casting using glycine-nitrate nanopowder

Formation features of MgO–Y2O3 nanocomposite of complex shape through aqueous slip casting using glycine-nitrate nanopowder

Effect of steel-refractory reactions on inclusion modification in lanthanum-, cerium-, and yttrium-added steels

Effect of steel-refractory reactions on inclusion modification in lanthanum-, cerium-, and yttrium-added steels

Ternary Ni-Ce-Mg-O Composites: In-Depth Optical Spectroscopy Study and Catalytic Performance in CO Oxidation

In the present work, ternary Ni-Ce-Mg-O composites containing various amounts of NiO and CeO2 were synthesized via a sol-gel approach. Aqueous solutions of cerium and nickel nitrates were introduced at the stage of hydrolysis of magnesium methoxide, which allowed for avoiding the use of expensive organic precursors. It was revealed that the properties of the composites were defined by the complex interactions between NiO, CeO2, and MgO components. In order to perform an in-depth characterization of the prepared samples, diffuse reflectance UV–vis and Raman spectroscopies were applied. According to the results of these methods, Mg2+ ions did not substitute Ce4+ ions in the CeO2 lattice. However, in the case of the Ni-containing samples, approximately 2–3% of the Ce4+ ions were substituted by Ni2+, thus resulting in the formation of vacancies in the CeO2. The strong interaction of NiO with MgO predictably resulted in the formation of NixMg1−xO solid solutions. When the NiO content in the sample was 20 wt%, the composition of the formed solid solution was estimated to be Ni0.60Mg0.40O. In addition, the presence of CeO2 affected the texture of the ternary composites, thus leading to a slight decrease in the specific surface area. The catalytic performance of the Ni-Ce-Mg-O composites was examined in the CO oxidation reaction under prompt thermal aging conditions. The choice of reaction conditions was due to a high sensitivity of the CO oxidation response toward the available metal surface area and possible metal-support interactions.

Research on Multi-Decision Sinter Composition Optimization Based on OLS Algorithm

The adjustment of sintering raw materials has a decisive influence on the composition of blast furnace slag and the properties of sinter. In order to smelt high-quality molten iron in the blast furnace, the composition of the sinter must be properly adjusted so that the composition of the blast furnace slag and the metallurgical properties of the sinter are optimal for the quality of the iron and are conducive to the smooth operation of the blast furnace. In view of the huge difference in the quality and price of sintering raw materials, this paper proposes an automatic sintering ore blending model to quickly configure sintering raw materials according to the requirements of the production line. This method is based on the calculation process of blast furnace charge, combined with the constraints of process composition and cost performance, to establish a multi-decision sintering ore blending model based on the OLS(Ordinary least squares) algorithm to automatically screen from available raw materials and give the sinter that meets the requirements of the furnace. The plan finally makes TFe, CaO, MgO, SiO2, TiO2, Al2O3, P, Mn, Na2O, K2O, Zn, and other components meet the requirements of the production line, and meet the cost performance requirements of the enterprise for sinter. The model can complete the screening and proportioning of 43 kinds of raw materials within 10 s, and its performance can meet the requirements of the production of variable materials. Combined with an example, a comparative analysis experiment is carried out on the accuracy and practicability of the designed sintering and ore blending model. The experimental results show that the accuracy and efficiency of the method proposed in this paper are higher than those of the current ore blending scheme designed by enterprise engineers. This method can provide an effective reference for the stable operation of the sintering production line.

Green functionalization of clinoptilolite with MgO nano-platelets as adsorbent for different species of antibiotic residuals (levofloxacin, ciprofloxacin, and pefloxacin); equilibrium studies

ABSTRACT Clinoptilolite zeolite was functionalized with green MgO nanoplatelets utilizing the extract of green tea leaves in the presence of sonication irradiation forming green nanocomposite (MgO(NP)/Clino). The MgO(NP)/Clino was evaluated as an enhanced adsorbent for three types of quinolones antibiotics (levofloxacin (LF), ciprofloxacin (CF), and pefloxacin (PF)). The maximum MgO(NP)/Clino uptake capacities for LF (169.4 mg/g), CF (196 mg/g), and PF (185.18 mg/g) was higher than both clinoptilolite and MgO components. The kinetic behaviors of LF, CF, and PF adsorption follow the Pseudo-First order model with equilibration intervals of 240 min (LF), 240 min (CF), and 180 min (LF). The equilibrium investigation suggests Langmuir isotherm properties of monolayer and homogenous uptake processes for LF, CF, and PF. The Gaussian energies of LF (6.65 kJ/mol), CF (6.3 kJ/mol), and PF (7.4 kJ/mol) related to physical, spontaneous, and exothermic adsorption mechanisms considering the thermodynamic parameters. The MgO(NP)/Clino achieved remarkable capacities for LF, CF, and PF antibiotics either in the co-presence of anions (SO4 2-, PO4 3-, and NO3 −) or metal cations (Cd2+, Zn2+, and Pb2+). The recyclability assessment of MgO(NP)/Clino emphasized its high stability considering the five studied cycles.

Machining characteristics of glass substrates containing chemical components in femtosecond laser helical drilling

The machining characteristics of glass substrates containing chemical components were investigated for the purpose of femtosecond laser helical drilling. A femtosecond laser of wavelength 1552 nm and pulse duration 800 fs was adopted in the laser machining system. The substrates investigated were aluminosilicate, soda-lime, and borosilicate glass. The chemical components contained in each glass substrate were quantitatively analyzed by laser ablation-induced chemical plasma mass spectrometry. The characteristics of the drilling conditions for each glass substrate were affected by its chemical components. As the wt% of Al2O3 and MgO components in the glass substrates increased, the ablation threshold energy of each substrate decreased, resulting in greater vertical speed of the laser head.

Gamma-Ray Attenuation Study for the Soils of Bursa, Turkey, in the Energy Range 59.5–1332.5 keV

In this study, the gamma radiation attenuation was experimentally investigated for soil samples with different texture collected from Bursa Province, Turkey. Firstly, physical and chemical properties (e.g., density, particle size distribution, lime content, organic matter and chemical composition) of these soils were determined by several methods. The transmission measurements of soils performed by using Am-241, Cs-137, Co-60 and Na-22 sources and 2 × 2 inch NaI(Tl) scintillation detector were used to calculate shielding parameters, mass attenuation coefficient, half value layer and tenth value layer values, of these samples in form of pressed powder pellets. The values of these important parameters have been found to vary with gamma-ray energy and chemical composition of the studied soil samples. For instance, the mass attenuation coefficients were decreased with increasing gamma-ray energies and, with the increase in contribution of MgO and Na components, caused better absorption. The effect of compression pressure on attenuation coefficient was also investigated, and better absorption was observed for the sample pressed by high value of press force.

Assessment the synthesis conditions of separable magnetic spinel nanocatalyst for green fuel production: Optimization of transesterification reaction conditions using response surface methodology

Abstract Fabrication of heterogeneous catalysts via simple routes for biodiesel production, which has high activity, reusability, simple separability, and less sensitivity to the quality of feedstock, is one of the main researches. Therefore, a magnetically separable MgO/MgAl0.4Fe1.6O4 nanocatalyst was fabricated by a combination of impregnation and solution combustion method. The effective parameters during loading the MgO on the support by impregnation method such as MgO content, calcination temperature, and calcination time were evaluated. The support modified by 25 wt% of MgO and then calcined at 550 °C for 3 h represented the appropriate crystalline structure, surface area, pore volume and size, and basicity. Consequently, the catalyst showed high activity in the transesterification reaction. For obtaining the highest conversion, the transesterification reaction conditions were also optimized via response surface methodology (RSM) in which the interaction of temperature with other variables was also significant as well as independent variables. The yield of 98.8% was obtained at the optimized conditions of 117.2 °C, 14.6 M ratio of methanol/oil, 3.3 wt% of catalyst, and 4.9 h of reaction time. The nanocatalyst showed suitable activity for the feedstock containing free fatty acid and water lower than 5 wt% and 1.2 wt%, respectively. The catalytic activity of the catalyst has remained constant for six times. Characterization of the used catalyst showed that pore-blocking along with leaching of some MgO components from the surface of the support, were the main reasons for reducing the conversion. The properties of biodiesel met the limitation of ASTM D6751 and EN14214 standards.

Phase-field study of dissolution behaviors of different oxide particles into oxide melts

Abstract This work utilized a quantitative phase-field model (PFM) to investigate dissolution behaviours of different oxide particles in various slag systems. The simulations could evaluate the influences of temperature, slag viscosity and slag composition on the dissolution time/rate of oxide particle. The simulated results are consistent with reported experimental data. A critical temperature and slag viscosity ratio (T/v), at which the MgAl2O4 and Al2O3 particles have the same dissolution rate, was determined as ~1190 [K/Pa.s]. It is impossible to get a fixed dissolution time/rate order of different oxide particles in general slag compositions due to the complicated variations of interfacial mobility coefficients. The Al2O3 particle is more sensitive to the variation of MgO and Al2O3 components in slag, compared with the MgAl2O4 particle. When the V-ratio (CaO/SiO2) increases up to a certain degree, the influence of MgO component in both MgAl2O4 and Al2O3 particles becomes minor.

Pedogenesis and Mineralogy of Alluvial Soils from Semi-arid Southeastern Part of Rajasthan in Aravalli Range, India

Abstract Three representative alluvial soils were studied from Kothari river basin of Bhilwara district in southeast Rajasthan to assess degree of chemical weathering and pedogenesis. Morphological, geochemical, mineralogical and other analytical investigations were carried out. Soils were classified as Entisols and Inceptisols. These soils are mostly sandy with more than 50% of fine and medium sand fractions, silt to clay ratio more than 0.45 and little textural variation suggesting more uniform weathering. These soils are slight to strongly alkaline with high exchangeable sodium (>15%) and cation exchange capacity less than 10 cmol(+)kg-1. Mineralogical investigations showed the dominance of micas and smectites in Pedon 1 (P1) and Pedon 2 (P2) and increase of smectites and micas in Bw3 horizon of P3 under strong alkalinity and high silica activity with limited lessivage. The low chemical index of alteration (CIA) in soils further indicated an incipient pedogenesis with a relative proportion of mica-smectite composition. The A-CNK-FM diagram shows abundance of CaO + Na2O + K2O as against Fe2O3+ MgO components under limited leaching environment and chemical weathering. The results of bivariate plot of SiO2 to (Al2O3 + K2O + Na2O) indicated the past weathering which influenced by prevailing arid climate in the region.

Hard x-ray standing-wave photoemission insights into the structure of an epitaxial Fe/MgO multilayer magnetic tunnel junction

The Fe/MgO magnetic tunnel junction is a classic spintronic system, with current importance technologically and interest for future innovation. The key magnetic properties are linked directly to the structure of hard-to-access buried interfaces, and the Fe and MgO components near the surface are unstable when exposed to air, making a deeper probing, nondestructive, in-situ measurement ideal for this system. We have thus applied hard x-ray photoemission spectroscopy (HXPS) and standing-wave (SW) HXPS in the few kilo-electron-volt energy range to probe the structure of an epitaxially grown MgO/Fe superlattice. The superlattice consists of 9 repeats of MgO grown on Fe by magnetron sputtering on an MgO(001) substrate, with a protective Al2O3 capping layer. We determine through SW-HXPS that 8 of the 9 repeats are similar and ordered, with a period of 33 ± 4 Å, with the minor presence of FeO at the interfaces and a significantly distorted top bilayer with ca. 3 times the oxidation of the lower layers at the top MgO/Fe interface. There is evidence of asymmetrical oxidation on the top and bottom of the Fe layers. We find agreement with dark-field scanning transmission electron microscope (STEM) and x-ray reflectivity measurements. Through the STEM measurements, we confirm an overall epitaxial stack with dislocations and warping at the interfaces of ca. 5 Å. We also note a distinct difference in the top bilayer, especially MgO, with possible Fe inclusions. We thus demonstrate that SW-HXPS can be used to probe deep buried interfaces of novel magnetic devices with few-angstrom precision.

Effects of chemical composition of fly ash on compressive strength of fly ash cement mortar

Abstract The effect of the chemical composition of the amorphous and crystalline phases of fly ash on the compressive strength of fly ash cement mortar was studied. The fly ash cement mortars were made by replacing 25 wt% of cement with 16 types of fly ashes, and the specimen’s compressive strengths were evaluated. The compressive strength increased with the mortar’s age due to differences in pozzolanic reactivity. The effects of various chemical parameters of the fly ash were analyzed. The pozzolanic reaction of fly ash was significantly affected by SiO2, Al2O3, and Fe2O3 components, which form the framework of the glass phase, and CaO, MgO, Na2O, and K2O components, which depolymerize the glass structure.

Crystallization characteristics prediction of coal slags based on SiO2–Al2O3–CaO–Fe2O3–MgO components

Abstract Crystallization inside the liquid slag can increase the viscosity, affecting flow down the wall which is associated with the temperature of critical viscosity ( T cv ). Four groups of synthetic slags with different Si/Al, Si + Al, CaO, Fe 2 O 3 ratios were sorted to study the crystallization characteristics including the crystallization tendency as well as crystallization temperature ( T crys ). Samples with base–acid ratio (R > 0.7) and Si/Al in the range of 1–4 are liable to crystallize with obvious crystallization peak on DSC curve, and the influence of R is more than that of Si/Al. The crystallization temperature ( T crys ) is found to display a linear relationship with the liquidus temperature ( T liq ). The deviation of real coal slag with synthetic slag is associated with the crystalline phases as well as the raw minerals present in the ash.

Multilateral approaches for investigation of particle stickiness of coal ash at low temperature fouling conditions

Particle stickiness is a key parameter for increasing ash deposition in gasification process. We conducted multilateral investigations to evaluate particle stickiness of coal ash at low temperature fouling conditions through Watt and Fereday’s viscosity model, dilatometry (DIL) and laser flash apparatus (LFA) technique. Seventeen coals were employed for ash deposition experiments under gasification condition through drop tube furnace (DTF). The low viscosity not only led to increasing ash deposition behavior, but also increasing the particle size of deposited ash. From DIL analysis, the ash sintering behavior increased with increasing temperature due to increase of particle stickiness. The high amount of Fe2O3, CaO and MgO components resulted in low sintering temperature and high reduction of physical length. Through LFA analysis, the thermal conductivity increased with increasing temperature, because of increasing particle stickiness. In addition, its value was correlated with the propensity of common fouling indices.

Structural and electrochemical characterization of the Ca50Mg20Cu25Zn5 amorphous alloy

Abstract The quaternary Ca 50 Mg 20 Cu 25 Zn 5 metallic glass in the form of ribbons and plates was successfully fabricated by melt-spinning and copper-mold casting. The structure characterization of the alloy in as-cast state was performed by using X-ray diffraction method. The Reverse Monte Carlo modeling was carried out to obtain structural model of the alloy in the form of ribbon. Moreover, the corrosion behavior of glassy plates was studied by electrochemical measurements and immersion tests in 1, 2 and 3.5% NaCl solution (pH = 5.4) at room temperature. As suspected the lowest corrosion activity of the alloy was observed in 1% NaCl solution. The post-corrosion tests were conducted by scanning electron microscopy and energy-dispersive X-ray spectroscopy to examine the corrosion products and chemical composition of the corroded surfaces. The XPS measurements were used to better understand corrosion behavior of the alloy after immersion during the open-circuit conditions. The corrosion surface products were identified to be CaO, MgO, Mg(OH) 2 and CaCO 3 components. The ZnO and CuO compounds were formed on the surface of glassy samples.

Biodiesel production from Jatropha Curcas oil using strontium-doped CaO/MgO catalyst

Abstract The synthesis of methyl ester (ME) as biodiesel from Jatropha oil and MeOH was investigated using CaO/MgO doped with strontium catalyst (Sr2+-CaO/MgO). This catalyst was prepared by co-precipitation method and compared with its uni- or bi-corresponding component catalysts in terms of physical properties and catalytic activities. The results indicated that the Sr2+ dopant played a key role in enhancing the catalytic performance of CaO and MgO components while MgO reduced the overall particle size and improved the catalyst reusability. The synthesized Sr2+-CaO/MgO catalyst was also studied at various transesterification conditions to determine the optimal conditions. The maximum ME content of 99.6% was obtained at 65 °C for 2 h and the MeOH-to-oil molar ratio of 9:1 with the catalyst amount of 5 wt%. At these conditions, the Sr2+-CaO/MgO catalyst could be reused up to four times while maintaining high activity with the ME content higher than 90%.

Characteristics of Basalt Materials Derived from Recycling Steel Industry Slags

In this study, Fe-Ni slag, converter slag and dephosphorization slag generated from the steel industry, and fly ash or bottom ash from a power plant, were mixed at an appropriate mixing ratio and melted in a melting furnace in a massproduction process for glass ceramics. Then, glass-ceramic products, having a basalt composition with SiO2, Al2O3, CaO, MgO, and Fe2O3 components, were fabricated through casting and heat treatment process. Comparison was made of the samples before and after the modification of the process conditions. Glass-ceramic samples before and after the process modification were similar in chemical composition, but Al2O3 and Na2O contents were slightly higher in the samples before the modification. Before and after the process modification, it was confirmed that the sample had a melting temperature below 1250 °C, and that pyroxene and diopside are the primary phases of the product. The crystallization temperature in the sample after modification was found to be higher than that in the sample before modification. The activation energy for crystallization was evaluated and found to be 467 kJ/mol for the sample before the process modification, and 337 kJ/mol for the sample after the process modification. The degree of crystallinity was evaluated and found to be 82% before the process change and 87% after the process change. Mechanical properties such as compressive strength and bending strength were evaluated and found to be excellent for the sample after process modification. In conclusion, the samples after the process modification were evaluated and found to have superior characteristics compared to those before the modification.

Role of Magnesium Silicates in Wet-Kneaded Silica–Magnesia Catalysts for the Lebedev Ethanol-to-Butadiene Process

Wet-kneading is a technique commonly used for the synthesis of SiO2–MgO catalysts for the Lebedev ethanol-to-butadiene process, with catalyst performance known to depend heavily on the preparation parameters used in this method. Here, the large influence of Mg precursor and MgO content on morphology, chemical structure (as determined by TEM(-EDX), FT-IR, XRD and solid-state 1H–29Si cross-polarized MAS NMR), and on catalyst performance is demonstrated. The Mg precursor used is found to influence the extent of magnesium silicate formation during wet-kneading, as estimated from TEM and FT-IR, which, in turn, was found to correlate with catalyst performance. Accordingly, the catalyst synthesized from a nanosized Mg(OH)2 precursor (SiO2–MgO (III)nano), showing the highest degree of chemical contact between the SiO2 and MgO components, gave the highest butadiene yield. Variation of the Mg/Si ratio in a series of SiO2–MgO (III)nano materials showed a volcano-type dependence of the butadiene yield on MgO content....

Study of the impact of solidifier inorganic components on the performance of a solidifiable gel plugging fluid

Abstract To solve the problems occurring during the treatment process in the case of any malignant lost circulation, such as the “door sealed” phenomenon, this paper studied a new type of solidifiable gel plugging fluid system. The door sealed phenomenon is caused during the addition of the blocking materials to the drilling fluid, when the weak gel fails to significantly improve the stratum bearing capacity, causing the gel plugging agent to be easily eroded. This erosion results in a lack of strength in the later period. Unlike the addition of various conventional chemical conditioning agents in the plugging fluid system, to optimally adjust the plugging fluid properties, this paper studied its impact on the system sedimentation stability, rheology, compressive strength, and so on by changing the percentage of the component substances, such as bentonite, CaO, MgO, and Al 2 O 3 , and analyzed the test samples and microstructure via X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM) tests. In the analyses, bentonite was found to be able to adjust the sedimentation stability and shear thinning behavior. In addition, the solidifiers CaO, MgO, and other components were found to be able to increase the compressive strength of the samples. The studies indicated that this system could adjust the component percentage according to the actual leakage situation of oil/gas wells to meet the construction requirements while providing a certain basis for the selection of other chemical conditioning agents.

Cracking Characteristics of Simulated Dust-Containing Coal Pyrolysis Volatiles over Regenerated Nickel-Based Catalysts

Two catalysts, 2%NiO/1%CeO2–Al2O3 and 2%NiO/1%CeO2/2%ZrO2–Al2O3, were employed in the conversion of tar in coal pyrolysis volatiles to investigate the interrelationship between dust collection and tar cracking as well as the effect of Ce/Zr doping on catalyst performance. In a fixed-bed catalytic reactor, a tar model mixture (57 wt % toluene, 14 wt % methylnaphthalene, 14 wt % cyclohexane, and 15 wt % dodecane) and simulated dusts (various metal oxides) were introduced to mimic real coal pyrolysis volatiles. The catalytic cracking activity of the latter catalyst increased with increasing temperature, space velocity, and water/model tar ratio, whereas the former catalyst exhibited the opposite trends, except with respect to temperature. Because of the formation of a Ce–ZrO2 solid solution, the latter catalyst showed higher stability. During cycling tests, the deactivation of 2%NiO/1%CeO2–Al2O3 was observed in the seventh reaction-regeneration cycle. Nickel aggregation, observed on the surface of the catalyst by XRD analysis, may account for the deactivation. Dust deposition on the catalyst surface had a significant influence on tar modification, and the interaction mechanism between dust deposition and coke formation was clarified. The electron probe microanalysis results showed that SiO2 tends to promote carbon deposition, whereas MgO and Fe2O3 components have a negative influence on carbon deposition. This study can serve as a reliable reference for the practical development and modification of purification processes for coal pyrolysis volatiles.