Aluminum-containing Compounds Research Articles

Thermochemical study of the detonation properties of boron- and aluminum-containing compounds in air and water

Thermochemical study of the detonation properties of boron- and aluminum-containing compounds in air and water

Enrichment of low-grade phosphorites by the selective leaching method

Abstract The selective leaching method presents a new and innovative approach for the enrichment of low-grade phosphate raw materials. The use of acetic acid as a reagent in the leaching process allows for the selective dissolution of carbonates, potassium-, and aluminum-containing compounds, offering a promising solution for the improvement of the recovery rates of valuable phosphorus compounds. This study presents the results of research on the selective leaching of carbonates from low-grade phosphate raw materials and evaluation of its efficiency using a combination of SEM, energy-dispersion and chemical analysis, X-ray diffraction, differential thermal, IR-Fourier spectroscopic, and mineralogical analysis techniques. The results showed an increase in the content of phosphorus(v) oxide from 14% to 22% through the selective leaching process. The enriched phosphate raw materials were also found to be suitable for the production of phosphorus-containing products. This research highlights the potential of the selective leaching method to overcome the challenges faced in the enrichment of low-grade phosphorites and provide a more efficient and sustainable solution for the industry.

Fabrication and characterization of porous mullite ceramics derived from fluoride-assisted Metakaolin-Al(OH)3 annealing for filtration applications

In this work, polycrystalline mullite whiskers are synthesized by fluoride-assisted method from metakaolin and several aluminum-containing compounds such as γ-Al(OH)3, AlF3·3H2O, and α-Al2O3 (corundum). The mullite formation and crystallization are assessed both in ex situ and in situ synchrotron X-ray diffraction experiments under synthesis conditions. Polycrystalline mullite starts to form from metakaolin, Al(OH)3, and AlF3·3H2O reactants at 680 °C, whereas mullite does not form even at 1000 °C when corundum is used. Porous mullite ceracmics are fabricated at sintering temperatures between 1000 and 1700 °C and tested for water permeance. Scanning Electron Microscopy (SEM) and synchrotron X-ray tomography (μCT) reveal that ceramics are comprised of pore channels with an interlocked network of mullite whiskers. With competitive porosity (up to 63 %), compressive strength (up to 20 MPa), and pure water flux (up to 579 L/m2·h at 1 bar), fabricated mullite ceramics are promising candidates for water filtration and purification.

Synthesis and Properties of Modified Aluminum-Containing Framework Compounds

In this work, nickel- and iron-modified aluminum-containing framework compounds—highly porous stable nanomaterials—have been prepared for the first time using magnetron sputtering, an environmentally friendly method. The materials have been characterized by a variety of physicochemical methods: BET measurements, atomic force microscopy, X-ray diffraction, thermogravimetric analysis, and IR spectroscopy. We have assessed the catalytic activity of the synthesized bimetallic framework compounds for the hydrogen peroxide oxidation of an azo dye. The results demonstrate that the addition of a small amount of these catalysts leads to an increase in reaction rate constant. The nickel- and iron-modified aluminum-containing framework compounds have been shown to retain their performance for at least four cycles (with allowance for regeneration via triple treatment with ethanol). A mechanism has been proposed for the hydrogen peroxide oxidation of the dye in the presence of the synthesized metal complexes, in which hydroxyl radicals act as an oxidizing species.

Foundry Core Mixtures with Orthophosphoric Acid and Different Aluminum-Containing Compounds

The scientific and practical issues of the development of core mixtures for foundry, based on phosphate binding materials, are considered. The binder presented in this article differ from those previously known by the fact that scarce prepared metal phosphate binding components and powder solidifiers are not used to produce them. As a result, all developed binders are different forms of aluminum phosphates. It is shown that to obtain them it is possible to use combinations of orthophosphoric acid with aluminum-containing materials of different chemical nature.The formation of high-strength phosphate binders in the interaction of phosphoric acid with aluminosilicates and sludge wastes of aluminum production has been established. They are rationally used for processes of thermal strengthening of cores in the temperature range of 200…300 °C.The formation of binders in the interaction of orthophosphoric acid with inorganic aluminum salts are theoretically proved and practically confirmed. The results are confirmed by thermodynamic calculations, as well as by X-ray phase analysis.The compositions of the developed core mixtures and examples of their application for obtaining high-quality castings from iron and steel are presented.

Methods for High-Purity Aluminum Oxide Production for Growth of Leucosapphire Crystals (Review)

Methods for the preparation of raw materials to produce leucosapphire are considered. It is shown that the main directions in the production of high-purity aluminum oxide raw materials are: electrochemical oxidation of aluminum, decomposition of alkoxides, high-temperature treatment of aluminum oxide in a halogen-containing atmosphere, and preliminary purification of aluminum-containing compounds followed by their decomposition. It is shown that methods of the purification of aluminum hydroxide and oxide obtained by the Bayer process are the most promising for industrial use. These methods include the complex purification and simultaneous preparation of ceramic preforms starting from aluminum hydroxides or oxides by their treatment in subcritical or supercritical steam and the following heat treatment in a halogen-containing medium.

Guitarrins A-E and Aluminumguitarrin A: 5-Azaindoles from the Northwestern Pacific Marine Sponge Guitarra fimbriata.

Guitarrins A-E (1-5), the first natural 5-azaindoles, and aluminumguitarrin A (1a), the first aluminum-containing compound from marine invertebrates, were isolated from the sponge Guitarra fimbriata. The structures of these compounds were established using detailed analysis of 1D and 2D NMR data, mass spectra, and X-ray analysis of 1 and 1a. Compound 3 was proved to be a natural inhibitor of alkaline phosphatase.

Spark plasma sintering of Al-doped ZrB2–SiC composite

This research presents the influence of Al addition on microstructure and mechanical behavior of ZrB2–SiC ultra-high temperature ceramic matrix composite (UHTCMC) fabricated by spark plasma sintering (SPS). A 2.5 wt% Al-doped ZrB2–20 vol% SiC UHTCMC was produced by SPS method at 1900 °C under a pressure of 40 MPa for 7 min. The microstructural and phase analysis of the composite showed that aluminum-containing compounds were formed in-situ during the SPS as a result of chemical reactions between Al and surface oxide films of the raw materials (i.e. ZrO2 and SiO2 on the surfaces of ZrB2 and SiC particles, respectively). The Al dopant was completely consumed and converted to the intermetallic Al3Zr and Al4Si compounds as well as Al2O3 and Al2SiO5. A relative density of 99.8%, a hardness (HV5) of 21.5 GPa and a fracture toughness (indentation method) of 6.3 MPa m1/2 were estimated for the Al-doped ZrB2–SiC composite. Crack bridging, branching, and deflection were identified as the main toughening mechanisms.

Production of alumo-matrix composite material modified by nanostructured cubic boron nitride

The structure and microhardness of an aluminum alloy with additives of nanostructured cubic boron nitride (cBN) after treatment under high pressure and temperature are investigated. А nanostructured powder of cBN with primary particles within 50–200 nm is used as a filler. A preliminary chemical-thermal modifying of the nanostructured cBN, which consists in its high-temperature annealing in the temperature range of 750–950 °C in a medium of aluminum-contai ning compounds, is carried out to increase the chemical affinity of the nanostructured cBN to the aluminum matrix. It is shown that the modifying of nanostructured cBN with aluminum increases the strength of the additives retention in the aluminum matrix. At the same time the increase in the concentration of BN additives from 1.5 to 5 wt.% as well as the increase in the treatment temperature at a fixed pressure promotes the increase in the microhardness of the material by a factor of 1.5 to 2 as compared with the base aluminum alloy without the addition of a modifier. An increase in the cBN concentration to 5 % by weight results in an increase in the fraction of smaller particle conglomerates (1–5 μm) in the material and in a decrease in the size of large inclusions to 10–20 μm. In this case, the distribution of BN particles in the aluminum matrix is more uniform in comparison with a material with a cBN content of 1.5 wt.%. In the material with the growth of temperature up to 1000 °С, cBN in aggregates is recrystallized with the formation of single-crystal (polycrystalline) particles with the size of 1–10 μm with faceting specific for cBN micron particles.

Development of Colorimetric and Ratiometric Fluorescence Membranes for Detection of Nitrate in the Presence of Aluminum-Containing Compounds.

In this study, a quantitative analysis of nitrate in aqueous solution was performed through the combination of an oxazine170 perchlorate–ethyl cellulose (O17-EC) membrane with aluminum-containing compounds. Aluminum of Devarda’s alloy (DA) or a clay hydrotalcite (HT) was employed for the reduction of nitrate to produce ammonia, and the produced ammonia was detected by the O17-EC membrane. The method of combining the O17-EC membrane with aluminum compounds has showed a broad detection range of nitrate. That is, the DA was combined with the O17-EC membrane and showed the linear nitrate detection ranges of 1–10 mM and 10–100 mM, while the O17-EC membrane immobilized with the clay HT showed a linear detection range of 0.1–1 mM nitrate. The visual color transition of the nitrate-sensing membranes at different nitrate concentrations was clearly observed under sunlight or irradiation of a light-emitting diode (LED) at an excitation wavelength of 470 nm (LED470).

Effect of crystal size on zinc stabilization in aluminum-rich ceramic matrix

With aluminum as the predominant element, incineration residues from municipal solid waste and sewage sludge may be reused as precursors for zinc stabilization. As solid-state reactions are influenced by the crystal sizes of the reactants, the aluminum-containing components with different crystal sizes in the incineration residues may affect zinc transformation and immobilization. In this study, Al2O3 was prepared with a variety of crystal sizes to simulate the aluminum-rich incineration residue matrix, and ZnO was mixed with Al2O3 to study the zinc incorporation mechanisms. The crystal sizes of Al2O3 were determined using Rietveld refinement. Quantification results showed that ~ 30% of zinc was incorporated into the ZnAl2O4 spinel when Al2O3 with the largest crystal size was used. However, the zinc transformation was enhanced twofold when the Al2O3 precursor had the smallest crystal size. This study confirmed the potential enhancement of zinc immobilization by nanoscale crystals in simulated aluminum-rich incineration residues. By improving zinc stabilization efficiencies using poorly crystallized aluminum-containing compounds instead of increasing the energy consumption by increasing the sintering temperatures, we can achieve an economic and environmental win–win scenario for the beneficial utilization of incineration residues of municipal solid waste and sewage sludge.

Crystallization of gibbsite from synthetic chromate leaching solution in sub-molten salt process

For the clean and economical production of chromium compounds, it is crucial to remove aluminates from chromate alkali solutions and utilize aluminum-containing compounds. In this work, carbonization was used to remove aluminates from a synthetic chromate leaching solution containing a high K2O/Al2O3 mole ratio. The influence of reaction temperature, carbonization time, flow rate of carbon dioxide, and seed ratio on the precipitation of Al was investigated. The optimal output was obtained under the following experimental conditions: a reaction temperature of 50 °C, a carbonization time of 100 min, a carbon dioxide flow rate of 0.1 L/min, and a seed ratio of 1.0. Gibbsite was obtained following carbonization. The structure and morphology of the gibbsite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and laser particle size analyzer. The particle size distribution and morphology of the gibbsite were significantly influenced by the experimental conditions. The gibbsite had a mean particle size (d50) of 16.72 μm. The thermal decomposition of the gibbsite was analyzed by XRD and the decomposition path was determined. The obtained coarse α-Al2O3 precipitate, which contains 0.08% Cr2O3 and 0.10% K2O, was suitable for subsequent utilization.

Hydration of portland cement in the presence of aluminum-containing setting accelerators

Portland cement hydration in the presence of two different aluminum-containing compounds, highly dispersed amorphous Al(OH)3 and aqueous solution of aluminum hydroxosulfate Al(OH)1.78(SO4)0.61, was studied by solid-state 27Al and 29Si NMR spectroscopy.

DRIFTS study of the interaction of the AlEt 3 cocatalyst with the internal donor ethyl benzoate in supported Ziegler–Natta catalysts

The interaction of AlEt 3 cocatalyst with the internal donor (ethyl benzoate–EB) in the supported Ziegler–Natta (TiCl 4/EB/MgCl 2) catalysts and the EB/MgCl 2 support was studied by DRIFT spectroscopy. For EB/MgCl 2 samples, it was shown that AlEt 3 firstly removed the more weak surface complexes of EB from the MgCl 2 surface and competed with EB at adsorbtion for releasing sites of the MgCl 2 surface. EB, as the external donor, keeps constant the initial content and distribution of surface complexes of EB at the interaction of the AlEt 3/EB mixture with the EB/MgCl 2 support. At the interaction of AlEt 3 with the TiCl 4/EB/MgCl 2 catalysts one type of surface complexes of EB is mainly removed. A part of removed EB adsorbs again on the catalyst surface in the form of complexes with aluminum-containing compounds. At the interaction of the catalyst with the AlEt 3/EB mixture the EB content in the catalyst changes slightly, but the distribution of different surface complexes of EB in the catalyst changes noticeably compared to that in the initial catalyst. EB, as the external donor, adsorbs both on surface MgCl 2 sites released at the removal of the internal donor and on aluminum-containing compounds adsorbed on the catalyst surface.

How alum works

For more than 70 years, alum has been used as a trusty aide to improve antibody responses to vaccines. But how this aluminum-containing compound boosts the response to vaccines has been a mystery. On page 869, Kool et al. expose its mysterious mechanism; they find that alum causes cells to produce a stimulator of dendritic cells (DCs). Figure 1 Mice injected with antigens mixed with alum produce uric acid that then attracts monocytes. DCs were once the favored hypothetical link between alum and B cells, as they activate CD4+ T cells, which can then enhance B cell activation and antibody production. But DCs were later dismissed when it was found that they were not stimulated by alum in vitro. These in vitro results are now shown to be a red herring by Kool et al., who find that alum activates DCs in vivo by provoking the secretion of uric acid—a molecule that is triggered by tissue and cell trauma. The injection of alum, the group found, induced an influx of neutrophils and inflammatory cytokines and chemokines—a combination that was previously seen in response to the injection of uric acid into mice. In mice injected with antigens mixed with alum, uric acid levels increased within hours. The uric acid might be released by the cells' lining the body's cavities that turn necrotic after contacting the alum. The absence of these uric acid sources in in vitro assays might have led to the previous misleading results. In response to the uric acid, inflammatory monocytes flocked to the injection site, took up the antigens, and broke them down into T cell–stimulating epitopes. The monocytes then migrated to lymph nodes, where they matured into DCs and activated CD4+ T cells. Without alum, the antigens were not taken up at the injection site. Still, they eventually reached lymph nodes via the flowing lymph. The resident node DCs, however, did not process the alum-free antigens efficiently or express T cell costimulating receptors. The resulting subdued immunity was similar to that seen in mice that were depleted of inflammatory monocytes or those injected with enzymes that degrade uric acid.

Thermodynamics of the Decomposition Processes of Donor–Acceptor Complexes MX3⋅en⋅MX3 and MX3⋅en

The structural and thermodynamic properties of the donor-acceptor (DA) complexes of Group 13 metal halides (MX3) with ethylenediamine and their decomposition products have been studied theoretically at the B3LYP/LANL2DZ(d,p) level of theory. Gas-phase dissociation into various components and HX elimination reactions are considered. Both processes are endothermic but favored by entropy. Complexes of 2:1 composition are predicted to be stable in the gas phase up to 640-1000 K. It is found that complexation with the second acceptor molecule lowers the HX elimination enthalpy; in turn, HX elimination increases DA bonding with a second MX3 molecule. Exceptionally high values of the dissociation enthalpies (310-390 kJ mol(-1)) and HX elimination reactions (360-420 kJ mol(-1)) of the amido compounds MX2NHC2H4NH2 and MX2NHC2H4NHMX2 make them important intermediates in the decomposition processes. Dissociation reactions of the complexes are more favorable than HX elimination reactions; however, the subsequent oligomerization and cyclization processes of coordinationally unsaturated amido and imido compounds may facilitate HX elimination. Since HI elimination reactions are predicted to be the least endothermic, and aluminum-containing compounds have the strongest M-N dissociation enthalpies, it is expected that compounds based on aluminum iodide are promising objects for experimental studies.

Preparation and characterization of nickel–titanium composite xerogel catalyst for CO2 reforming of CH4

The effects of the parameters of the sol–gel catalyst preparation such as hydrolysis ratio, acid/alkoxide ratio, and calcination temperature on surface area, porous structure, crystal structure and surface properties of nickel–titanium (Ni–Ti) composite xerogel catalyst were studied. The optimum hydrolysis ratio and acid/alkoxide ratio were determined under which conditions and 453K calcination temperature, a Ni–Ti xerogel catalyst with a surface area of 426m2/g was made. Increasing the calcination temperature would lead to dramatic decrease in surface area and collapse in porous structures. To compensate this deleterious effect, aluminum-containing compound was added into the precursor mixture in sol–gel preparation and the resultant Ni–Ti–Al composite xerogel catalyst had a significantly higher surface area even after undergoing a calcination temperature as high as 973K. This xerogel catalyst showed comparably high activity for carbon dioxide reforming of methane where high temperature calcination is inevitable.

Safety Evaluation of Dietary Aluminum

Aluminum is a nonessential metal to which humans are frequently exposed. Aluminum in the food supply comes from natural sources, water used in food preparation, food ingredients, and utensils used during food preparations. The amount of aluminum in the diet is small, compared with the amount of aluminum in antacids and some buffered analgesics. The healthy human body has effective barriers (skin, lungs, gastrointestinal tract) to reduce the systemic absorption of aluminum ingested from water, foods, drugs, and air. The small amount of aluminum (<1%) that is systemically absorbed is excreted principally in the urine and, to a lesser extent, in the feces. No reports of dietary aluminum toxicity to healthy individuals exist in the literature. Aluminum can be neurotoxic, when injected directly into the brains of animals and when accidentally introduced into human brains (by dialysis or shrapnel). A study from Canada reports cognitive and other neurological deficits among groups of workers occupationally exposed to dust containing high levels of aluminum. While the precise pathogenic role of aluminum in Alzheimer's disease (AD) remains to be defined, present data do not support a causative role for aluminum in AD. High intake of aluminum from antacid for gastrointestinal ailments has not been reported to cause any adverse effects and has not been correlated with neurotoxicity or AD. Foods and food ingredients are generally the major dietary sources of aluminum in the United States. Cooking in aluminum utensils often results in statistically significant, but relatively small, increases in aluminum content of food. Common aluminum-containing food ingredients are used mainly as preservatives, coloring agents, leavening agents, anticaking agents, etc. Safety evaluation and approval of these ingredients by the Food and Drug Administration indicate that these aluminum-containing compounds are safe for use in foods.

27Al NMR MAS study of [formula omitted] systems

The 27Al NMR MAS spectra of surface species of aluminum-containing compounds AlEt 3 − n Cl n ( n = 0–3) on MgCl 2 have been measured. The data obtained indicate that 5- and 6-coordinated aluminum compounds form on the MgCl 2 surface. The majority of the AlCl 3 supported in small amounts on MgCl 2 was found to be 4-coordinated.

An InAlAs/InGaAs metal-oxide-semiconductor field effect transistor using the native oxide of InAlAs as a gate insulation layer

We report the growth, fabrication, and electrical characterization of InAlAs/InGaAs n-type depletion-mode, metal-oxide-semiconductor field effect transistors (MOSFETs) utilizing the thermally formed native oxide of InAlAs as a gate insulating layer. The native oxide of InAlAs, consisting mostly of aluminum–oxygen complexes, is formed in an elevated temperature environment with water vapor as the oxidizing species. This native oxidation process is similar to that used to oxidize other aluminum-containing compounds in the GaAs-based material system, such as AlGaAs and InAlP. The InGaAs MOSFETs having a gate length ∼8 μm exhibit a maximum gm∼6 mS/mm.