Magnesium Precursors Research Articles

Co-immobilization of magnesium precursor and Candida rugosa lipase on alumina via covalent bonding for biodiesel production

Catalyst development is one of the most challenging aspects in biodiesel production due to the compatibility issue with the feedstocks and catalyst poisoning upon exposure to process conditions. In the present research, chemoenzymatic catalyst was prepared by impregnation of magnesium aluminate (MA) on alumina support, modifying the support using activating agent, and immobilization of Candida rugosa lipase (CRL) onto the support. The optimum immobilization condition was resulting in 85.07 % of activity recovery of immobilized lipase, equivalent to 30.53 % of immobilization efficiency. The catalysts were characterized through XRD, FTIR, FESEM-EDX, NAA and CO2-TPD confirming the mixture of AlO(OH), magnesium aluminate (MA), (MgNO3)2 and Mg2+ on the support. CRL/L-lysine/MA showed remarkable improvement in thermal stability (40 − 70℃), solvents tolerance (ethanol, methanol, isopropanol, tert-butanol), and storage stability at 30 ℃, as compared to free CRL. CRL/L-lysine/MA successfully produced biodiesel yield up to 87.10 % at 200.71 rpm of agitation speed, 13.58 % (w/w) of water content, 10 h reaction time, 15 % (w/w) of catalyst loading, at 50 ℃, using 1:12 of oil to methanol molar ratio, and retaining 46.60 % of biodiesel yield after six cycle. The CRL/L-lysine/MA demonstrated novel catalysts characteristics comprising chemical and biological active species on a single support for biodiesel production from waste cooking oil (WCO).

Study on the mechanism of controlling the morphology of basic magnesium carbonate prepared under different hydration conditions

Basic magnesium carbonate is gaining prominence in flame retardant materials due to its excellent flame-retardant properties and clean decomposition products. This study investigates a hydration-carbonation method to address challenges related to the preparation, morphology control, and stability of magnesium basic carbonate. The impact of hydration conditions on the morphology of the carbonate was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicate that spherical magnesium basic carbonate with regular morphology and uniform particle size can be achieved at a hydration temperature of 50°C for 1.5 hours. However, extending the hydration time and increasing the temperature resulted in irregular morphologies. Molecular dynamics simulations using the CASTEP and Forcite modules of Materials Studio were employed to understand the influence of hydration-carbonation conditions on the carbonate's morphology. The simulations revealed that the (1 1 1) and (2 0 0) crystal faces of MgO, with higher surface energies, promote the formation of precursor magnesium hydroxide nuclei, leading to heterogeneous magnesium alkali carbonate at elevated temperatures. Prolonged hydration time resulted in fragmented carbonate structures. To control the morphology of magnesium alkali carbonate, it is essential to optimize hydration temperature and duration. The simulation results corroborate experimental findings, providing deeper insights into the liquid-gas-solid adsorption relationships during the carbonation process. This study offers valuable guidelines for the controlled synthesis of magnesium basic carbonate, enhancing its applicability in flame retardant materials.

Studies on silver-doped magnesium ferrite utilizing the sol–gel process in terms of structure, magnetism, electricity, and electrochemistry

Silver added magnesium ferrite (Mg1-xAgxFe2O4) nanofine grains were prepared by the sol–gel technique from magnesium, silver, and ferrous precursor materials, maintaining the pH value that was subsequently investigated for sensing applications. X-ray diffraction (XRD) analysis of the ferrite samples showed (Mg1-xAgxFe2O4) cubic spinel structure, larger crystallite size, and other characteristics. Using Fourier transform infrared spectroscopy, the active and functional groups with potential stretching analysis were extracted (FTIR). Using an energy dispersive X-ray (EDAX) spectrum and a scanning electron microscope (SEM), the surface characteristics, features, and the samples purity were examined. The magnetic behavior was examined using the vibrating sample magnetometer (VSM) in relation to pertinent parameters like saturation magnetization (Ms), coercivity (Hc), and retentivity (Mr). It was found that the greater Ms in 1.0 is ferromagnetic. The LCR meter was used to estimate the dielectric constants (ε'&ε''), loss (tanδ) with AC conductivity (σAC), and cyclic-voltammetry was used to assess the electrochemical behavior of the samples. A study is conducted on potential polarizations at both ranges of frequencies. The acquired facts are thoroughly analyzed and comprehended.

Effect of substrate temperature on growth mechanism and properties of PEALD-MgO dielectric films for amorphous-IGZO TFTs

Magnesium oxide (MgO) films have been prepared by plasma enhanced atomic layer deposition with bis(cyclopentadienyl)magnesium precursor and oxygen plasma reactant at substrate temperature between 150 °C and 450 °C. The structural, morphological, optical, and chemical properties of the prepared MgO films were studied by spectroscopic ellipsometer, grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS). The electrical property of MgO film was obtained by performing capacitance-voltage measurement on the Al/MgO/Si structures. The experiment result shows that growth rate of MgO film decreases with the deposition temperature increased. GIXRD analysis presented that MgO films are cubic with predominantly (220) crystal orientation. XPS analysis shows that ratio of Mg/O is highest in MgO film prepared at 350 °C. To illustrate the possible applications of MgO film as a gate dielectric in thin film transistor (TFT), indium‑gallium‑zinc oxide (IGZO) was used as channel layer. The optimized IGZO/MgO TFT showed an electron mobility of 1.63 cm2/Vs, an on/off current ratio of 106, and a subthreshold swing of 0.50 V/decade at a low operation voltage of −0.11 V.

Enhancing Arsenate Removal Efficiency Using Sewater Bittern-Derived MgO Nanoparticles/PVDF-HFP Electrospun Nanofibre Composites

MgO nanoparticles (MgO NPs) incorporated PVDF-HFP nanofibers have been synthesized using the electrospinning method to remove arsenic from polluted water. MgO nanoparticles were synthesized from seawater bitterns and used as magnesium precursors. The synthesized materials were characterized using various techniques, and their adsorption capacities were evaluated against arsenic under different conditions. The results showed that the maximum adsorption for As(V) adsorption was 41.47 mg g-1 for PVDF-HFP/MgO 30% (w/w), which equals 179.69 mg g-1 based on the weight of bare MgO NPs and achieved at pH 11, a contact time of 420 minutes, and an adsorbent weight of 0.0125 g. Incorporating MgO NPs into the nanofiber matrix can enhance its stability, further increase the adsorption capacity. This study demonstrates the potential of using PVDF-HFP/MgO nanofiber composites to treat arsenic-containing wastewater and further provide commercial benefits for seawater bitterns by serving as a precursor for producing functional nanomaterials.

Whitening and purification of calcined talc powders from black talc by the milling and reactive calcination with magnesium precursors

Whitening and purification of calcined talc powders from black talc by the milling and reactive calcination with magnesium precursors

Synthesizing Nanoporous Stainless Steel Films via Vacuum Thermal Dealloying

Vacuum thermal dealloying is a recently developed technique and was newly introduced to produce nanoporous metals, due to its intriguing advantages, i.e., preventing oxidation and producing no chemical waste, etc. Here, we report on the fabrication of nanoporous stainless steel films by vacuum thermal dealloying of sputtered stainless steel–magnesium precursor films. It was found that crack-free nanoporous stainless steel films can be successfully attained under a broad temperature range of 450–600 °C, with a dealloying time of 0.5–2 h. The resulting structure and ligaments were temperature- and time-dependent, and moreover, the condition of “600 °C + 2 h” generated the most homogeneous structure. Moreover, small amounts of residual Mg were found at pore sites in the resultant structures, suggesting that the dealloying was not fully complete.

Proteolytically Resistant Bioactive Peptide-Grafted Sr/Mg-Doped Hardystonite Foams: Comparison of Two Covalent Functionalization Strategies.

Hardystonite-based (HT) bioceramic foams were easily obtained via thermal treatment of silicone resins and reactive oxide fillers in air. By using a commercial silicone, incorporating strontium oxide and magnesium oxide precursors (as well as CaO and ZnO), and treating it at 1100 °C, a complex solid solution (Ca1.4Sr0.6Zn0.85Mg0.15Si2O7) that has superior biocompatibility and bioactivity properties compared to pure hardystonite (Ca2ZnSi2O7) can be obtained. Proteolytic-resistant adhesive peptide mapped on vitronectin (D2HVP), was selectively grafted to Sr/Mg-doped HT foams using two different strategies. Unfortunately, the first method (via protected peptide) was unsuitable for acid-sensitive materials such as Sr/Mg-doped HT, resulting in the release of cytotoxic levels of Zinc over time, with consequent negative cellular response. To overcome this unexpected result, a novel functionalization strategy requiring aqueous solution and mild conditions was designed. Sr/Mg-doped HT functionalized with this second strategy (via aldehyde peptide) showed a dramatic increase in human osteoblast proliferation at 6 days compared to only silanized or non-functionalized samples. Furthermore, we demonstrated that the functionalization treatment does not induce any cytotoxicity. Functionalized foams enhanced mRNA-specific transcript levels coding IBSP, VTN, RUNX2, and SPP1 at 2 days post-seeding. In conclusion, the second functionalization strategy proved to be appropriate for this specific biomaterial and was effective at enhancing the material's bioactivity.

Biochar-supported magnesium oxide as high-efficient lead adsorbent with economical use of magnesium precursor

With unique porous structure inherited from lignocellulose, biochar was an appropriate carrier for small-size MgO materials, which could simplify the synthetic process and better solve agglomeration and separation problems during adsorption. Biochar-supported MgO was prepared with impregnation method. Under different synthesis conditions, the obtained MgO presented diverse properties, and moderate pyrolysis condition was conducive to the improvement of Mg conversion rate. The Pb(II) capacity was highly correlated with Mg content, rather than the specific surface area. Reducing the pyrolysis temperature or increasing the usage of supporter could improve adsorption efficiency when using Mg content-normalized capacity as the criterion. The better release ability of Mg, contribute by the higher extent of hydration and better spread of MgO, were the critical factors. The maximal Mg content-normalized capacity could reach 0.932 mmol·mmol-Mg−1 with the mass ratio of biochar/MgCl2·6H2O = 4:1 at the pyrolysis temperature of 600 °C. Considering the ultimate utilization efficiency of Mg in precursor, the optimum Mg consumption-normalized capacity was 0.744 mmol·mmol-Mg−1 with the mass ratio of biochar/MgCl2·6H2O = 1:1 at 600 °C.

Thermodynamic Study of a Volatile Complex of Magnesium Benzoyltrifluoroacetonate with N,N,N',N'-Tetramethylethylenediamine

To expand the library of volatile magnesium precursors certified for effective use in chemical gas-phase deposition of the corresponding oxide or fluoride layers, a thermodynamic study of the mixed ligand complex Mg(tmeda)(btfac)2 (tmeda is N,N,N',N'-tetramethylethylenediamine, btfac is benzoyl trifluoroacetonate) have been performed. The melting process has been studied using DSC (Tm = 459.4 ± 0.3 K,= 42.9 ± 0.4 kJ/mol); the sublimation process has been studied using the flow (transfer) method in the temperature range 407–447 K (= 163 ± 6 kJ/mol, ΔsublS427 = 293 ± 14 J/(mol K)). The substance passes into the gas phase with partial decomposition. Thermodynamic modeling of the composition of condensed phases formed from Mg(tmeda)(btfac)2 with the addition of H2 or O2 has been performed depending on the temperature (700–1300 K), total pressure (133–13 332 Pa), and the ratio of the reagent gas to the precursor (0–300). The data obtained can be used to determine the experimental parameters of the processes for obtaining functional layers. Comparison of the results with a similar trifluoroacetylacetonate complex made it possible to quantitatively reveal the effect of replacing the methyl group in the anionic ligand with a phenyl one.

Greening Pathways for Synthetic Talc Production Based on the Supercritical Hydrothermal Flow Process

Recent efforts in chemistry have led to development of a fast and continuous process for the production of synthetic talc in a supercritical hydrothermal reactor. This attractive process compatible with industrial requirements leads to advantageous physicochemical characteristics including submicrometer size, hydrophilicity, and high chemical and mineralogical purity. In addition, the high speed of the process and moderate reaction conditions have potential advantages from a viewpoint of the impacts on the environment. To verify environmental advantages and seize further opportunities to improve environmental performance, the current study evaluates the new process using the life cycle assessment (LCA) methodology. A cradle-to-gate assessment considers the production of synthetic talc from different magnesium and reagent acid precursors at different concentrations. The findings suggest high impacts of precursors (65–94%, depending on their concentration) and low impacts of process energy and water. Substituting magnesium acetate with magnesium sulfate could reduce greenhouse gases from 4.8 to 2.6 kgCO2 and cumulative energy use from 86 to 34 MJ per 1 kg of synthetic talc. Discussion draws on previous LCA studies on the supercritical hydrothermal process and applications of synthetic talc considering its environmental performance and characteristics in comparison to the conventional (natural) talc.

Recent developments in the reduction of unsaturated bonds by magnesium precursors

AbstractScientists have witnessed significant breakthroughs ins‐block metal chemistry. Over the past few years, several applications in catalysis associated with alkaline‐earth metal catalysts have been established owing to their abundance and lower cost. These catalysts have proved to be essential alternatives to transition metal catalysts. Several research groups have recognized the importance of magnesium complexes as highly active metal catalysts in the reduction of a series of unsaturated substrates for the synthesis of ubiquitous compounds necessary for industrial purposes. This minireview presents, based on studies published in the past recent years, a detailed discussion of catalytic hydroelementation on C–X (X = C, N, O, B, Si, S) multiple bonds, promoted by novel magnesium metal catalysts.

Calcium and Magnesium Bis(β-diketiminate) Complexes: Impact of the Alkylene Bridge on Schlenk-Type Rearrangements.

Dinuclear heteroleptic alkaline-earth-metal complexes are interesting synthetic targets because the close proximity of two metals allows for cooperative effects. However, these complexes are also prone to undergoing Schlenk-type rearrangements, affording less-active homoleptic complexes. Here we present the metalation of bis(β-diketimine) ligands possessing flexible bridging groups, i.e., 1,2-ethylene, 1,3-propylene, and trans-1,2-cyclohexylene, using calcium and magnesium precursors. Four mononuclear homoleptic calcium complexes were obtained, highlighting the pronounced tendency of calcium to undergo Schlenk-like redistributions. In the case of magnesium, however, the bridging group plays a crucial role, yielding seven dinuclear heteroleptic complexes but also one mononuclear and one dinuclear homoleptic complexes. In addition, a trinuclear mixed heteroleptic-homoleptic magnesium complex, which is a rare example of an intermediate of the Schlenk equilibrium, was isolated.

Urea-Assisted Synthesis of Nanospherical and Plate-Like Magnesium Oxides for Efficient Removal of Reactive Dye Wastes

Nanospherical and plate-like magnesium oxide has been successfully synthesized by urea precipitation method for the first time. A magnesium oxide precursor was prepared by heating MgCl2 solution with urea for 12 hours at 90°C. Then the calcined precursor was analysed by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and high-resolution transmission electron microscopy (HR-TEM). In the presence of the nonionic surfactant Triton X-100 in the system, the reaction yielded in nanospheres of MgO contrast to the plate-like MgO in the absence of the surfactant. The precursor and the calcined product appeared in similar morphologies under SEM in both cases with a slight reduction of size upon calcination. The final product was confirmed as MgO using XRD and FT-IR spectroscopic methods. In TGA, both samples showed similar mass loss values upon elimination of adsorbed water molecules and decomposition of the precursor into MgO; however, the nanospherical MgO sample showed an additional weight loss due to elimination of the associated surfactant molecules. The efficiency of removing reactive dye wastes was quantified by UV-visible spectroscopy using reactive yellow dye. Plate-like MgO showed a porous structure under HR-TEM analysis in the dye adsorption study, and both plate-like and nanospherical MgO showed good dye adsorption capability. MgO nanospheres showed higher capacity of dye adsorption compared to plate-like MgO, explained by its higher surface are-to-volume ratio, while the plate-like MgO also performed well due to having a nanoporous structure. These nanomaterials will offer high potential in purifying waste water and as well in recovering expensive dye products.

The Effects of Various Parameters of the Microwave-Assisted Solvothermal Synthesis on the Specific Surface Area and Catalytic Performance of MgF2 Nanoparticles.

High-specific-surface-area MgF2 was prepared by microwave-assisted solvothermal synthesis. The influences of the solvent and the magnesium precursors, and the calcination atmospheres, on the nanoparticle sizes and specific surface areas, estimated by X-Ray Powder Diffraction, N2 sorption and TEM analyses, were investigated. Nanocrystallized (~7 nm) magnesium partially hydroxylated fluorides (MgF2−x(OH)x) with significant specific surface areas between 290 and 330 m2∙g−1 were obtained. After activation under gaseous HF, MgF2−x(OH)x catalysts underwent a large decrease of both their surface area and their hydroxide, rates as shown by their 19F and 1H solid-state NMR spectra. Expect for MgF2 prepared from the acetate precursor, an activity of 30–32 mmol/h∙g was obtained which was about 40% higher compared with that of MgF2 prepared using Trifluoroacetate method (21.6 mmol/h∙g).

In Situ Formation of Metal Hydrides Inside Carbon Aerogel Frameworks for Hydrogen Storage Applications

Nano-confined chemical reactions bear great promise for a wide range of important applications in the near-to-medium term, e.g., within the emerging area of chemical storage of renewable energy. To explore this important trend, in the present work, resorcinol-/formaldehyde-based carbon aerogels were prepared by sol-gel polymerisation of resorcinol, with furfural catalysed by a sodium-carbonate solution using ambient-pressure drying. These aerogels were further carbonised in nitrogen to obtain their corresponding carbon aerogels. Through this study, the synthesis parameters were selected in a way to obtain minimum shrinkage during the drying step. The microstructure of the product was observed using Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) imaging techniques. The optimised carbon aerogels were found to have pore sizes of ~21 nm with a specific accessible surface area equal to 854.0 m2/g. Physical activation of the carbon aerogel with CO2 generates activated carbon aerogels with a surface area of 1756 m2/g and a total porosity volume up to 3.23 cm3/g. The product was then used as a scaffold for magnesium/cobalt-hydride formation. At first, cobalt nanoparticles were formed inside the scaffold, by reducing the confined cobalt oxide, then MgH2 was synthesised as the second required component in the scaffold, by infiltrating the solution of dibutyl magnesium (MgBu2) precursor, followed by a hydrogenation reaction. Further hydrogenation at higher temperature leads to the formation of Mg2CoH5. In situ synchrotron X-ray diffraction was employed to study the mechanism of hydride formation during the heating process.

Dual Valorization of Olive Mill Wastewater by Bio-Nanosynthesis of Magnesium Oxide and Yarrowia lipolytica Biomass Production.

This research investigates an efficient dual valorization of olive mill wastewater in the biosynthesis of magnesium oxide nanoparticles and in the depollution of the effluent by Yarrowia lipolytica growth evaluation. After removal of polyphenols, the recovered biophenols were reacted with the magnesium precursor to provide magnesium oxide nanoparticles. In order to confirm the biosynthesized magnesium oxide nanoparticles, several analyses were undertaken. The Fourier transform infrared spectrum gives a broad absorption at 658 cm-1 confirming the presence of the magnesium oxide nanoparticles, while the UV/VIS absorption spectroscopy reveals an intense transition with a maximum absorption at 300 nm. The X-ray diffraction and transmission electron microscopy analyses show that nanoparticles are in pure cubic crystalline with spherical and hexagonal shapes (average size is 19.4 nm). The zeta potential analysis illustrates a negative potential proving a good stability of the biosynthesized nanoparticles. Nanoparticles were assigned for their in vitro antibacterial activity against Escherichia coli, Enterobacter aerogenes, Salmonella typhimurium, Staphylococcus cohnii, and Bacillus niacini. The evaluation of the growth of Yarrowia lipolytica on the recovered olive mill wastewater after removal of polyphenols yielded 3.2 g/L of the Yarrowia biomass in 72 h without nutriment additions, providing an important decrease of chemical oxygen demand (73 %).

Structure-performance relationships of magnesium-based CO2 adsorbents prepared with different methods

Magnesium-based adsorbents present great potential in separating CO2 from flue gas stream. To satisfy the requirement of efficient CO2 capture, it is imperative to select suitable methods for preparing MgO adsorbents with good physicochemical properties. In this study, MgO adsorbents were prepared with different methods using MgCl2·6H2O as magnesium precursor, and the effect of synthesis method on their structure-performance relationships were investigated. It is found that MgO adsorbents prepared with different methods exhibited varied physicochemical properties, and these were associated with their diverse CO2 adsorption capacities. Amongst the different MgO adsorbents, the sample prepared with the solid-state chemical reaction method (MgO-SR) featured good textural properties (high specific surface area and total pore volume of 100.03 m2/g and 0.67 cm3/g), preferable surface morphology (sheet-like structure with reduced layer diffusion resistance) and excellent CO2 adsorption capacity (2.39 mmol CO2/g). The solid-state chemical reaction method endowed the adsorbent with abundant surface basic active sites, and CO2 molecules interacted with the weak sites (OH group), medium sites (Mg-O pairs) and strong sites (O2−) to form stable bicarbonate, bidentate and unidentate carbonates. The experimental CO2 uptakes were in good agreement with the values predicted by the Avrami fractional kinetic model. Physical adsorption and chemisorption coexisted in the CO2 adsorption process and the chemisorption sites played a dominant role. The approach enlightens the facile fabrication of cost-effective MgO adsorbents from waste precursors for large-scale CO2 capture applications.

Preparation of MgO-Templated N-Doped Mesoporous Carbons from Polyvinylpyrrolidone: Effect of Heating Temperature on Pore Size Distribution

Magnesium oxide (MgO)-templated nitrogen (N)-doped mesoporous carbons were prepared by using polyvinylpyrrolidone (PVP) as a raw material and magnesium lactate (Mglac) as a precursor for the MgO template to examine the influence of heating temperature and MgO precursor (magnesium acetate was used in similar previous studies) on the pore size and nitrogen content. The MgO-templated carbon was obtained by heating the PVP/Mglac mixture in an inert atmosphere followed by an acid treatment for MgO removal. The mesopore size of the carbons was approximately 4 nm regardless of heating temperature, corresponding to the crystallite size of the MgO template estimated via X-ray diffraction. This indicates that the mesopore of approximately 4 nm was generated using the MgO template. However, larger pores were also found to exist. This result indicates that the larger pores generated through processes other than the MgO templating, likely the thermal decomposition of PVP, are contained in the templated carbon. The volume of the larger pores and the specific surface area increased with increasing heating temperature. The nitrogen content of the carbon decreased as the heating temperature was increased, but it was found to be irrelevant to the MgO precursor.

Hydroupgrading of Bio-Oil Over PtMg/KIT-6 Catalysts.

The objective of this study is to evaluate the catalytic potential of PtMg/Al-KIT-6 during the hydroupgrading of a mixture composed of C15-C18 alkane as a model compound of bio-oil obtained by a hydrodeoxygenation of palm oil. Al-KIT-6 was prepared through a post-alumination method using KIT-6, after which platinum and magnesium precursors were impregnated onto the synthesized Al-KIT-6. PtMg/Al-KIT-6 catalysts were shown to have a well-arranged mesoporous structure, a large surface area, and a large pore size. The jet-fuel yield (55-59%) in the hydroupgrading of the long-chain n-alkane mixture over PtMg/Al-KIT-6 catalysts was much higher than that over the PtMg/KIT-6 catalyst, which could be ascribed to the higher number of acid sites of the PtMg/Al-KIT-6 catalysts. The highest isomer selectivity of the PtMg/Al-KIT-6(20) catalyst can be attributed to the strong acidity as well as the abundance of acid sites. PtMg/Al-KIT-6 catalysts can be effective catalysts for producing jet fuel through the hydroupgrading of bio-oil.