MgO Precursor Research Articles

Salt-Composition-Controlled Precipitation of Triple-Salt-Promoted MgO with Enhanced CO2 Sorption Rate and Working Capacity

Triple-salt-promoted MgO composites (NaNO3, Na2CO3, and LiNO3) for precombustion CO2 capture were developed by a precipitation method with a controllable salt composition. MgO precursors were mixed and aged with salts to control the composition and morphology. The MgO composites exhibited a CO2 sorption capacity of 73 wt % in pure CO2 at 240 min and 300 °C and achieved a sorption capacity of 25 wt % within 10 min because of a high sorption rate. When a cyclic test was conducted with pure CO2 sorption for 60 min at 325 °C and N2 regeneration for 15 min at 425 °C (60/15 min cycle) as a reference, the cyclic capacity was 45 wt % after 30 cycles. On the other hand, considering the applicable capture processes, the sorption capacity during a fast cycle (10/5 min cycle) was 18 wt % under the same gas and temperature conditions. Finally, the working capacity of the MgO composite was evaluated under a simulated emission gas (29% CO2, 3% H2O, and balance N2) at 300 °C for sorption and CO2 at 450 °C for regeneratio...

New continuous solid solution in the Zn2InV3O11–Mg2InV3O11 system

A new substitutional solid solution of the composition Zn2−xMgxInV3O11 was found to form in the Zn2InV3O11–Mg2InV3O11 system. The new phase was obtained by solid-state reactions. The phase was synthesized by heating in air adequate mixtures of ZnO, V2O5, In2O3 with a precursor of MgO and was characterized using XRD, DTA–TG, IR and SEM/EDX methods. The effects of the degree of Mg2+ ion incorporation in the crystal lattice of Zn2InV3O11 replacing Zn2+ on the unit cell volume, thermal stability, morphology and IR spectra of Zn2−xMgxInV3O11 in the range 0.0 < x < 2.0 were determined. A phase diagram up to solidus line of the pseudobinary Zn2InV3O11–Mg2InV3O11 system was constructed.

Surfactant-driven direct synthesis of a hierarchical hollow MgO nanofiber–nanoparticle composite by electrospinning

A single step synthesis of hierarchical MgO nanoparticle–nanofiber composite using surfactant driven electrospinning.

Green Synthesis of MgO Nanoparticles and it Antibacterial Activity

This article reports a facile approach for the synthesis of MgO nanoparticles (MgO NPs) using aqueous leaf extracts of Pisidium guvajava (P. guvajava) and Aloe vera (A. vera). The synthesized MgO NPs were characterized using UV–visible spectroscopy, FTIR, XRD, FESEM, EDAX, and XPS analysis. Further antimicrobial activity of synthesized MgO NPs extensively studied for Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) both of bacterial species well controlled MgO NPs. Both of the precursor material can be used as a reducing and capping agent. UV absorbance exhibits on 221 nm which confirms MgNO3 reduced as MgO. FTIR results confirm that plant precursors act as reducing and capping agents. X-ray diffraction confirms that the final products are pure and FCC crystal phase. FESEM with EDAX represented the synthesized MgO NPs having cubic shape and fully composed of MgO. XPS analysis indicates that the as-prepared MgO nanoparticles were composed of MgO and plant precursor. Antibacterial activity of as-prepared MgO NPs responded both of E. coli and S. aureus.

Wollastonite-diopside glass-ceramic foams from supercritical carbon dioxide-assisted extrusion of a silicone resin and inorganic fillers

Biphasic ceramics based on wollastonite (CaSiO3) and diopside (CaMgSi2O6) have been recently proposed as valid biomaterials. Silicone resins, filled with inorganic reactive powders, have a great potential in both synthesis of the desired phases and in the shaping in form of highly porous foams. In particular, glass-ceramic foams have been already obtained from a liquid silicone, filled with CaO and MgO precursors and with hydrated salts, such as sodium borate and phosphate. The foaming is due to the release of water vapour within the polymer (at 300–350°C), before its conversion into amorphous silica, and reaction with Ca and Mg oxide, by heat treatment (above 1000°C). In this paper we discuss a significant extension of the approach, referring to a well-known commercial solid silicone. In order to prevent the cross-linking of the silicone (that would compromise the foaming), the polymer and the fillers were mixed by means of conventional polymer extrusion assisted by supercritical carbon dioxide. Finely powdered extrudates could be easily foamed, at 350°C, due to the release of water vapour and CO2. Owing to the uniform cellular structure (with a total porosity of about 80%) and the absence of cracks, the final products, after firing at 1100°C, showed an excellent crushing strength (in the order of 10MPa), far exceeding that of previously developed foams.

Preparation of MgO nanomaterials by microemulsion-based oil/water interface precipitation

This paper presented a novel microemulsion-based method for the preparation of MgO nanomaterials. Briefly, in a paraffin-in-water microemulsion system, we firstly synthesized Mg5(CO3)4(OH)2·4H2O/paraffin composites, the precursor of MgO, via an interface-controlled homogenous precipitation. By calcinating the composite precursor at different temperatures, MgO nanomaterials with varied morphologies could be obtained. A flower-like 3D hierarchical structure was achieved when applying lower calcination temperatures, which indeed preserves the morphology of the composite precursor. While at higher calcination temperatures, one can get the well-defined MgO nanoparticles. The prepared materials were thoroughly characterized by XRD, SEM and BET methods, and their application as adsorbents to remove Congo red from wastewater was demonstrated.

Morphological and surface structural evolutions of MgO particles from parallelograms to rods

The morphologies and surface structures of particles with different compositions are vital for determining their properties and applications. But the morphological and structural changes associated with the composition changes of MgO precursors and the physicochemical properties of the obtained MgO are barely studied. Herein we reported the morphology, surface structure and physicochemical property changes of MgO particles associated with the ratio of two basic precipitation reagents (Na2C2O4 and K2CO3) for the construction of MgO precursors. We also found that the physicochemical properties of the obtained MgO were closely related to the ratios of Na2C2O4 and K2CO3. When the ratio was 1 : 1, the generated MgO exhibited superior surface basicity and catalytic performance relative to others.

Development of mesoporous magnesium oxide–alumina composites for CO2 capture

Mesoporous magnesium oxide–alumina composites were synthesized by evaporation induced self assembly (EISA) in the presence of triblock copolymer Pluronic P123 in absolute ethanol solution. These mesostructures were prepared using Al(NO3)3∙9H2O and Mg(NO3)2·6H2O as alumina and MgO precursors, respectively. Block copolymer was completely removed by thermal treatment of as-synthesized samples at 350°C in flowing nitrogen. Thermally treated composites displayed relatively high specific surface area and large pore volume. Temperature programmed desorption (TPD) was used to investigate the active sites available on the surface of the aforementioned samples for CO2 sorption at 120°C. Magnesium oxide-alumina composite samples showed an enhanced CO2 uptake under flue gas conditions (100–150°C). The sample synthesized from Al(NO3)3∙9H2O) only showed adsorption capacity of about 1.30mmol/g. Incorporation of 10 molar% of MgO did not significantly increase the CO2 uptake of the alumina-based composite; however, incorporation of 30 molar% of MgO increased CO2 uptake up to 2.08mmol/g. An increase of the MgO content in the composite caused a gradual enhancement in the CO2 uptake; namely, the composite with 70% of MgO loading showed 2.87mmol/g CO2 uptake. High thermal and mechanical stability of the composites studied as well as their low cost, good resistance to the corrosion and oxidizing environment make these materials, especially MgO-rich composites, attractive candidates for CO2 capture at flue gas conditions.

Influence of MgO precursors on mechanically activated forsterite synthesis

Brucite-fumed silica and hydromagnesite-fumed silica mixtures were used to investigate the influence of MgO precursors on mechanically activated forsterite synthesis. The changes in morphology, chemical bond and phase composition of the ground and calcined mixtures were examined with scanning electron microscopy (SEM), Si 2p X-ray photoelectron spectroscopy (XPS) and 29Si magic angle spinning nuclear magnetic resonance (MAS-NMR), and X-ray diffraction (XRD), respectively. The XPS and MAS-NMR analyses show that high-energy milling generates more Mg–O–Si chemical bonds in the brucite-fumed silica mixture than in the hydromagnesite-fumed silica sample. This is because brucite has a higher concentration of Mg–OH bonds than hydromagnesite. However, single-phase forsterite forms at a higher temperature of 1000°C in the milled brucite-fumed silica mixture than that of 800°C in the ground hydromagnesite-fumed silica sample after the same grinding. The different forsterite completion temperature is probably due to the longer Mg2+ and Si4+ diffusion distance of over 500nm in the former milled mixture than that of less than 300nm in the latter ground sample.

Facile Synthesis of MgO Microspheres via Water-in-oil Emulsion Assisted with Homogeneous Precipitation

Abstract Water droplets containing MgCl2 and urea, as the water phase of xylene/water/span-80 water-in-oil (w/o) emulsion system, can act as microreactors where spherical MgO precursor powders with porous microstructure were obtained via homogeneous precipitation. By changing the volume ratio of span-80 to xylene, spherical powders with different sizes were synthesized, and the effect of span-80/xylene volume ratio on powder morphology was examined. The as-prepared powders as well as their precursors were characterized by means of field-emission scanning electron microscopy (FE-SEM), laser particle size analysis (LPS), N2-adsorption measurements (BET) and thermogravimetry and differential thermal analysis (TG-DTA). The TG-DTA result indicated that the optimal sintering temperature of precursor powders was 450 °C. The FE-SEM results showed that the span-80-to-xylene volume ratio had a marked effect on the morphology of powders. When the ratio was 1:40, the FE-SEM and LPS results confirmed the formation of the powder microspheres with a size range of 1–16 µm, and the surface area of the microspheres was about 75.7 m2 g−1 according to the BET result.

Bioactive Wollastonite-Diopside Foams from Preceramic Polymers and Reactive Oxide Fillers

Wollastonite (CaSiO3) and diopside (CaMgSi2O6) silicate ceramics have been widely investigated as highly bioactive materials, suitable for bone tissue engineering applications. In the present paper, highly porous glass-ceramic foams, with both wollastonite and diopside as crystal phases, were developed from the thermal treatment of silicone polymers filled with CaO and MgO precursors, in the form of micro-sized particles. The foaming was due to water release, at low temperature, in the polymeric matrix before ceramic conversion, mainly operated by hydrated sodium phosphate, used as a secondary filler. This additive proved to be “multifunctional”, since it additionally favored the phase development, by the formation of a liquid phase upon firing, in turn promoting the ionic interdiffusion. The liquid phase was promoted also by the incorporation of powders of a glass crystallizing itself in wollastonite and diopside, with significant improvements in both structural integrity and crushing strength. The biological characterization of polymer-derived wollastonite-diopside foams, to assess the bioactivity of the samples, was performed by means of a cell culture test. The MTT assay and LDH activity tests gave positive results in terms of cell viability.

Oxidative dehydrogenation and aromatization of n-octane over VMgO catalysts obtained by using different MgO precursors and different precursor treatments

VMgO catalysts with a V2O5 loading of 15% were prepared by the wet impregnation method. Catalysts synthesis was carried out by employing different MgO precursors (MgC2O4 and Mg(OH)2) and different precursors treatments (under vacuum and under static air). The synthesized catalysts were characterized by ICP-OES, BET, powder XRD, SEM, EDX, 51V NMR, H2-TPR, and NH3-TPD. The catalysts were tested for the oxidative dehydrogenation of n-octane using a continuous flow fixed bed reactor at GHSV of 8000h−1 and n-octane/O2 molar ratio of 0.8. Changing the above synthesis parameters led to the formation of catalysts with different morphologies, textural properties, and acidity. As a consequence, the results of the catalytic testing were also different, and treating the MgO precursors under vacuum induced a general positive effect on the catalytic performance. The aromatization of n-octane was predominantly via C1–C6 bonding.

聚乙二醇辅助合成氧化镁及其处理含铅溶液的性能

A novel hexagonal columnar MgO was synthesized by precipitation method assisted by structure director (PEG-10000). Experiment results show that this hexagonal columnar structure can be explained by self-assemble with layer by layer. The precursor of MgO was nesquehonite, and MgO with large surface area (> 55 m2/g) was obtained after calcination at 600℃. The adsorption performance of hexagonal columnar MgO was also studied in lead solution, and saturated adsorption was 390 mg/g. The results of adsorption are conformed to Langmuir model, which mean that the novel hexagonal columnar MgO has a high adsorption performance.

Effect of annealing temperature on structural and optical properties of Mg-doped ZnO nanoparticles and their photocatalytic efficiency in alprazolam degradation

Abstract Mg-doped ZnO nanocrystallites were prepared via conventional solid-state reaction when ZnO and MgO precursors were stoichiometrically mixed and heated at 700 °C, 900 °C and 1100 °C for 2 h in air atmosphere. Influence of annealing temperature on structural and optical properties of the obtained nanoparticles was investigated using X-ray diffraction, scanning electron microscopy, mercury intrusion porosimetry, Raman and UV–vis spectroscopy. The efficiency of Mg-doped ZnO water suspensions in the photocatalytic degradation of alprazolam, short-acting anxiolytic of the benzodiazepine class of psychoactive drugs, under UV irradiation was compared with efficiency of pure ZnO and TiO 2 Degussa P25.

Novel akermanite-based bioceramics from preceramic polymers and oxide fillers

Akermanite (Ca2MgSi2O7) ceramics have been successfully prepared by a novel approach, consisting of the heat treatment of silicone resins embedding MgO and CaO precursors, in the form of micro- and nano-sized particles, that act as reactive fillers. Phase purity was promoted by the use of nano-sized particles or by secondary additives, such as sodium borate. The use of hydroxyapatite as additional filler allowed the fabrication of monoliths with good specific mechanical properties, although with a complex phase assemblage. Sodium borate, besides favoring the crystallization of the desired silicate, promoted a substantial and homogeneous foaming of polymer/filler mixtures, leading to akermanite foams possessing good compressive strength.

Preparation of shaped magnesium oxide/carbon catalysts using rice grains as an exotemplate and carbon precursor

Biomorphic magnesium oxide and magnesium oxide/carbon catalysts have been synthesized via an in situ transformation technique using rice grains as a template and carbon precursor. During preparation, MgO precursors are dispersed on the surface of rice grains with the aid of the rice-cooking process, and further transformed into solid bases upon calcination. Biomorphic MgO/carbon materials are formed when calcination is performed in a nitrogen atmosphere. These particles are spindle shaped catalysts with a circumference of several millimeters. Pyrolysis at higher temperature aids in the formation of porous structures, and the resulting MgO/carbon materials display high specific surface area (>260m2/g) and more strongly basic sites. The presence of black carbon affects the catalytic behavior of MgO in the methylation of cyclopentadiene. These shaped MgO/carbon materials exhibit much higher catalytic performance than MgO at lower reaction temperatures.

Redox stability and electrical conductivity of Fe2.3Mg0.7O4±δ spinel prepared by mechanochemical activation

This paper addresses the potential of mechanochemical activation of MgO and α-Fe2O3 precursor powders to obtain Fe2.3Mg0.7O4 ceramics with enhanced redox stability and electrical conductivity. X-ray diffraction (XRD) and Mössbauer spectroscopy suggest the initial formation of the spinel phase after 5 h of high-energy milling in inert gas, but after 10 h of mechanoactivation, the precursor still comprised hematite as a major phase with minor amounts of magnesiowustite as by-product. The activated mixtures can be nearly completely converted to spinel solid solution by heating to 1173 K, whereas single-phase, dense spinel ceramics can be prepared by sintering at 1773 K in inert atmosphere. These ceramics demonstrated redox stability under mildly reducing conditions (p(O2) ∼ 10 Pa), as confirmed by XRD, thermogravimetry and electrical measurements. The electrical conductivity of Fe2.3Mg0.7O4 at this oxygen partial pressure is lower compared to magnetite, but it is still as high as 60 S/cm at 1073 K and 15 S/cm at room temperature. Cooling below 1473 K in air results in a drop of conductivity due to segregation of hematite phase at the grain boundaries. However, the phase separation is kinetically stagnated at 1073 K, and, after slight initial degradation, the retained electrical conductivity is more than 3 orders of magnitude higher compared to hematite and MgFe2O4 spinel.

Superb Adsorption Capacity and Mechanism of Flowerlike Magnesium Oxide Nanostructures for Lead and Cadmium Ions

A facile method based on microwave-assisted solvothermal process has been developed to synthesize flowerlike MgO precursors, which were then transformed to MgO by simple calcinations. All the chemicals used (magnesium nitrate, urea, and ethanol) were low cost and environmentally benign. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution TEM, and N(2) adsorption-desorption methods. These flowerlike MgO nanostructures had high surface area and showed superb adsorption properties for Pb(II) and Cd(II), with maximum capacities of 1980 mg/g and 1500 mg/g, respectively. All these values are significantly higher than those reported on other nanomaterials. A new adsorption mechanism involving solid-liquid interfacial cation exchange between magnesium and lead or cadmium cations was proposed and confirmed.

Processing and properties of sol gel derived alumina–carbon nano tube composites

High purity alumina–carbon nano tube (CNT) composites were prepared by an aqueous sol–gel processing route. CNTs were dispersed in alumina sol containing appropriate amount of MgO precursor. Aqueous slurry of alumina was seeded into the sol followed by gelation, drying and calcination at 1000°C for 1h. The calcined powder consisting of alumina-coated CNTs and alumina was milled, sieved, dried, pressed and pressureless sintered at 1400–1600°C for 1h in nitrogen atmosphere. Sintered samples were further isostatically hot pressed at 1300°C and the properties were compared with the pressureless sintered samples. Phase formation was followed by XRD study, CNT retention was confirmed by Raman studies and the samples were further characterized for mechanical and microstructural properties.

Investigation and Preparation of High Active Nano-MgO Thin Spherical Material

High active MgO precursor was prepared by high-temperature spray thermal decomposition method using saturated MgCl2 as raw materials. And high active nano-MgO thin spherical materials were prepared by MgO precursor being calcined at different temperatures after multiple hydration, purification, and filtration. The XRD, TG, DSC and SEM were employed to characterize the phase structure and micro-morphology of spherical materials whose formation mechanism was researched. And its activity (average pore size and surface area) was detected by using BET-BJH of N2 adsorption to get the optimum calcination temperature. The results showed that high active nano-MgO thin spherical material was periclase structure, its surface of nano-flake or rod-like, and thin sphere with diameter of 30∼100 nm and aperture of 10∼60 nm. The aperture was decreased while the surface area, microporous volume and surface activity were increased with preparation process were optimized, for example, calcination temperatures. Nano-MgO thin spherical material with a purity of 99.2 wt% was obtained at 900°C. And BET surface area of nano-sphere reached a maximum value of 31.6 m2/g with nest-like structure of particle uniform dispersion and average aperture of 11.2 nm. Meanwhile, the maximum absorption of N2 was gotten.