Aluminum Source Research Articles

Preparation of KI/KIO3/Methoxide Kaolin Catalyst and Performance Test of Catalysis in Biodiesel Production

Kaolin is a natural ingredient that is in abundance and has not been widely used. Kaolin is a source of silica (SiO2) and alumina (Al2O3) so that it can be used as a heterogeneous catalyst in biodiesel production. This research aims to examine the influence of using impregnated kaolin as a heterogeneous catalyst on production of biodiesel. Research methods include calcination of natural kaolin, impregnation of kaolin using KI, KIO3, and preparation of kaolin-methoxide in various concentrations, as well as biodiesel production using an impregnated kaolin catalyst. The catalyst was characterized using XRD and SEM. The catalyst was tested for basicity using the Hammet indicator method with acid-base titration. The biodiesel product obtained was analyzed using GCMS. The results of XRD analysis showed that 8% kaolin-methoxide catalyst had the highest crystallinity among the others. The crystallinity obtained was 87.84% with a composition of 15.79% SiO2 and 78.86% Al2O3. SEM image results also show a more visible crystal shape. The highest basicity of the catalyst obtained was 0.240 mmol. The highest biodiesel yield using 8% kaolin-methoxide catalyst is 99.48%.

Selective extraction of potassium from raw nepheline materials

The global aluminium industry is ever-changing and primarily relies on bauxite as its traditional source. However, due to the finite reserves of processed bauxite, alternative sources need to be found. Nephelines have emerged as potential alumina sources. In addition to alumina, nepheline processing can yield marketable products such as soda, potash, cement, and rare metals.The objective of this study was to identify the ideal conditions for selectively extracting potassium from alkaline leaching solutions while separating it from sodium alkali, aluminium, and silicon during the comprehensive processing of nepheline syenites from the Kubasadyr deposit. This approach involved a two-stage hydrothermal leaching process with an incremental calcium addition. Under optimal conditions, the potassium extraction in the alkaline solution reached 93.91 %. The resulting leaching solution served as a feedstock for potassium sulfate production through the crystallization method. The preliminary selective separation of potassium played a crucial role in mitigating its adverse effects on the extraction of aluminium, which is the primary processed product; thus, the economic viability of production was enhanced.

Growth of Spontaneous Nucleation AlN Crystals by Al-Base Alloy Evaporation in Nitrogen Atmosphere

Aluminum nitride (AlN) crystals with areas ranging from 1 mm2 to 2 mm2 were successfully grown through spontaneous nucleation at 1700 °C using a modified vapor transport method. In this approach, Cu–Al alloy served as the source of aluminum (Al), and nitrogen (N2) was employed as the nitrogen source. The morphology and crystalline quality of the AlN crystals were characterized by a stereo microscope, Raman spectrometer, photoluminescence (PL) and secondary-ion mass spectrometry (SIMS). Deposited on the graphite lid, the as-grown AlN crystals exhibited both rectangular and hexagonal shapes, identified as m-plane and c-plane AlN, respectively, based on Raman spectroscopy. The full width half maximum (FWHM) values of E2 (high) for the rectangular and hexagonal grains were measured to be 6.00 cm−1 and 6.06 cm−1, respectively, indicating high crystalline quality. However, PL and SIMS analysis indicated the presence of impurities associated with oxygen in the crystals. This paper elucidates the growth mechanism of the modified vapor transport method and highlights the role of the Cu–Al alloy in sustaining reactions at lower temperatures. The addition of copper (Cu) not only facilitates sustainable reactions, but also provides a novel perspective for the growth of AlN single crystals.

Extraction of alumina from fly ash by pyro-hydro metallurgical routes: A review

Fly ash is a resulting by-product formed due to the burning of pulverized coal on a steam-generating plant. Fly ash mainly contains alumina and silica, hence it can be an excellent secondary source for alumina. Today only 30% of global fly ash can be reused commercially, the remaining was dumped. This causes waste of resources and environmental pollution too. The alumina in the fly ash was in the form mullite phase which is a stable phase so decomposition of this phase is difficult. The mullite phase can be disilicated by calcination, roasting, etc which were pyro-metallurgical routes. Alumina can be extracted as aluminum hydroxide and other unstable forms from fly ash by hydrometallurgical routes. This process requires a huge amount of energy for reaction which is a major drawback of this process. Till now industrial extraction of alumina from fly ash cannot be feasible. Different researchers and scholars did various works to overcome this difficulty. This paper presents a review for extraction of alumina via these routes. It starts with different concepts used in extraction of alumina from fly ash. The middle portion presents the survey of work done by different scholars. The work finally concludes with future possibilties.

Synthesis of millimetre-scale HZSM-5 single crystals by secondary hydrothermal treatment

Millimetre-scale HZSM-5 single crystals were successfully synthesized by a two-step hydrothermal method. In the first step, millimetre-sized silicalite-1 single crystals were prepared by hydrothermal synthesis using quartz tube as siliceous source. In the second step, framework Al atoms were inserted into the single crystals of silicalite-1 by another hydrothermal treatment involving NaAlO2 as aluminium source. Through the characterizations of power and single crystal X-ray diffraction, optical microscope, ICP, 27Al MAS NMR, 29Si MAS NMR, and n-propylamine temperature-programmed decomposition (NPA-TPD), it was confirmed framework Al atoms with uniform spatial distribution can be inserted into giant single crystals of silicalite-1 with no obvious effects on the crystal structure, size and morphology. Such giant HZSM-5 single crystals are a promise candidate for the probe adsorption investigations, which can be applied in the measurement of framework Al spatial distribution. The strategy of insertion of aluminium or other heteroatoms of pure siliceous zeolite through secondary hydrothermal method provides a possible route to prepare giant single crystals that is difficult to synthesize directly.

Recycling of Spent FCC Catalysts: Conversion of Leached Residues to Zeolite ZSM-5.

The commercial recycling of spent FCC catalyst typically focuses on recovering only 1-3 % of rare-earth elements, with the remaining residues often disposed of in landfills. Here, we present a novel method to close a recycling loop for spent FCC catalyst. The method involves a series of leaching steps: Firstly, the spent catalyst material is leached with HNO3 to remove rare-earth elements such as La; second, solvothermal leaching with HCl removes most of Al and impurities like Fe, Ni and V; finally, a third leaching with H2SO4 removes Ti. The solid residues are then used to synthesize ZSM-5 without the addition of any extra silicon or aluminum sources after mild activation. The impurities in the synthesis gel strongly modify the properties of the zeolite, with ZSM-5 crystals containing higher levels of impurities exhibiting lower crystallinities, surface areas, acidities, cracking activities, as well as larger particle sizes.

Mechanistic Study of the Influence of Reactant Type and Addition Sequence on the Microscopic Morphology of α-Al2O3

To perform an in-depth study of the crystal growth habits and phase changes of alumina and its precursors in reaction systems, this paper studied the effects of reactant type and addition order on the morphology of alumina using hydrothermal methods with different precipitants and aluminum sources as reactants. Research has shown that sodium bicarbonate and ammonium bicarbonate can be used as precipitants to prepare adhered spherical alumina and irregular short rod alumina, while potassium bicarbonate can be used as a precipitant to prepare hexagonal flake alumina. Using aluminum sulfate octahydrate, aluminum chloride hexahydrate, and aluminum nitrate, nine hydrates were prepared as aluminum sources, and agglomerated alumina, irregular short rod-shaped alumina, and fused alumina were obtained. The order of reactant addition affects the precursor phase of alumina, thereby affecting the microstructure of alumina after calcination, resulting in flake alumina with pores and short rod alumina. The results of this paper will provide theoretical guidance for the preparation of alumina with different micromorphologies.

Magnetic properties of bauxites and pre-fused hydrothermal product (zeolite)

Bauxites are deposits rich in aluminium and iron oxides/hydroxides, formed by the weathering of aluminosilicates rocks under warm and humid conditions. Due to their mineralogical composition, bauxites represent the primary source for aluminum and, subordinately, iron production. However, these sediments rich in Si and Al can be also used as raw material for the synthesis of zeolite with magnetic properties thanks to the high availability of Fe. In this work, three bauxite samples collected from Upper Cretaceous deposits of southern Italy were characterized for their magnetic parameters and used for the synthesis of zeolite with LTA topology (zeolite A). The results indicate differences in antiferromagnetic behaviour among the three raw materials. All the synthetic products, instead, display the same antiferromagnetic behaviour thus suggesting that the method used for the zeolite crystallization neutralizes the parameters responsible for raw bauxite magnetic differences.

Effect of glass forming additives on low-activity waste feed conversion to glass

A significant effort was invested in the past to develop and refine mathematical models that relate the composition of nuclear waste glasses with their properties, such as viscosity, electrical conductivity, or chemical durability. However, less attention has been paid to the formulation of the melter feed itself, such as the chemical form and the particle size of the glass forming and modifying additives, which have a significant effect on the feed-to-glass conversion process during melting. To address this issue, we systematically changed the mineral composition of a simulated low-activity waste melter feed and inspected its melting behavior. When substituting minerals with corresponding oxides and hydroxides, we found that different alumina sources (kyanite, gibbsite, boehmite, or corundum) had the strongest effect on the feed melting process, whereas the sources of Ca, Mg, and Zr had little effect. The X-ray diffraction analysis showed that the alumina sources differ in their dissolution kinetics: early dissolving alumina sources, such as gibbsite (Al(OH)3) and boehmite (AlO(OH)), increase the transient glass-forming melt viscosity at early stages, when gases still evolve, causing extended foaming, whereas alumina sources that dissolve at high temperatures, such as kyanite (Al2SiO5) and corundum (Al2O3), keep the transient glass-forming melt viscosity low and lead to a faster foam collapse. Using a viscosity-composition relationship to estimate the viscosity of transient glass-forming melts in the primary foaming range, we found that the primary foam began to collapse at 360 to 800 Pa s, and fully collapsed between 65 and 260 Pa s. This result agrees with our previous studies, according to which, the glass-forming melt viscosity at the cold cap foam bottom ranged from 24 to 85 Pa s.

Preparation of monolithic Al2O3–SiO2 aerogels with high-temperature resistance using boehmite nanorods

In this study, monolithic Al2O3–SiO2 aerogels with excellent thermal stability were synthesized by ambient pressure drying (APD) or supercritical drying (SCD) using tetraethyl orthosilicate and boehmite nanorods (L = 20–30 nm, D = 3–5 nm) as precursors. The high specific surface area of aerogels prepared by APD or SCD was maintained after calcination at 800 °C (585 m2/g or 664 m2/g), 1000 °C (415 m2/g or 487 m2/g), and 1100 °C (175 m2/g or 231 m2/g). The anti-sintering mechanism of the aerogels prepared with boehmite nanorods as the aluminum source was discussed in detail. Successful preparation by APD offers the possibility of low-cost and large-scale application of monolithic Al2O3–SiO2 aerogels. Al2O3–SiO2 aerogels with excellent thermal stability have the potential to be used as high-temperature thermal insulating materials in aerospace applications.

Composite Molecular Sieve ZSM-5/MCM-48-Based Impregnation Modification for Efficient Adsorption of CO2

Micro/mesoporous materials are low-cost functional materials with the potential for CO2 adsorption. Modifying micro/mesoporous materials is significant for enhancing CO2 adsorption and their high-value utilization. Herein, the micro/mesoporous material of composite molecular sieve ZSM-5/MCM-48 (ZM) was synthesized by a two-step crystallization method using cetyltrimethylammonium bromide as a template, tetraethyl orthosilicate as a silicon source and ZSM-5 seed as part of silicon aluminum source. Tetraethylenepentamine (TEPA) and polyethyleneimine (PEI) were used as impregnation modifiers to modify ZM with amine groups. The results showed that with the increase of amine loadings, both ZM-T60 (Impregnated with TEPA) and ZM-P60 (Impregnated with PEI) functionalized adsorbents exhibited the best adsorption capacities of [Formula: see text] and [Formula: see text] at 60, respectively, when the loading of ZM sample was 60%. The adsorption kinetic analysis showed that the adsorption of CO2 by ZM-T60 and ZM-P60 was a chemisorption-dominated process accompanied by physical adsorption. After 10 adsorption/desorption cycles, the CO2 adsorption capacity of ZM-T60 and ZM-P60 decreased by 8.7% and 2.6%, respectively. This work demonstrates that impregnation modification of the composite molecular sieve to achieve efficient CO2 adsorption has practical application significance.

Hygienic assessment of aluminum intake in the adult population of Western Siberia

BACKGROUND: In recent decades, research has demonstrated the potential for adverse effects of aluminium on human health. However, there has been a lack of information regarding aluminum intake among different population groups in Western Siberia, thus emphasizing the significance of this study.
 AIM: To estimate aluminum intake by food consumption in the adult population of Western Siberia.
 MATERIAL AND METHODS: The study was conducted in 2019–2020 in the Omsk region. Dietary aluminum intake was assessed in 421 adult residents (177 men and 244 women) of the region using a food frequency questionnaire. The sample was similar to the general population of the region in terms of gender, age, and place of residence. The aluminum content in 160 food samples was determined earlier.
 RESULTS: The median daily intake of aluminum was 4.77 mg/day (3.679; 6.118). No differences in the aluminum intake was observed either by age (р=0.619) or by gender (р=0.334). The main dietary sources of aluminum were beverages (48.5%), vegetables (18.4%), and bakery (11.1%). Among single food products the main sources of aluminium were tea (45.5%), bread (6.7%) and cucumbers (5.3%).
 The proportion of aluminum consumed through vegetables tends to increase with age, whereas the opposite trend is observed for confectionery consumption.
 CONCLUSION: The dietary consumption of aluminum among the adult population in the Omsk region did not exceed the permissible levels. There were no variations in aluminum intake between men and women across different age groups. The primary source of aluminum in the diet of the Omsk region population is plant-based food.

The intricate roles of Al2O3 on the structure and electrochemical performances of LiNi0.5Co0.2Mn0.3O2 cathode materials

Severe capacity fading of in NCM layered oxide cathode materials has hampered their practical adoption. This problem can be effectively alleviated by the introduction of Al3+. Previous studies have shown that when Al3+ is introduced into the lattice to partially replace the transition metals, it acts as a structural stabilizer and inter-Al3+ does not participate in the redox reactions. However, the reaction of an aluminum source with lithium salts has not attracted enough attention in the synthesis of Al3+doped cathode materials. In this paper, Al2O3-modified LiNi0.5Co0.2Mn0.3O2 cathode materials are revisited by the solid-state reaction methods. Combined with XRD results, SEM and mapping analysis, it is found that during the heattreatment process, a part of Al3+ ions are doped into the lattice of the cathode material, and it is proved that most parts of Al2O3 react with LiOH⋅H2O to form α-LiAlO2, which is coated on the surface of the cathode material. Considering that lithium will be consumed because of the reaction between Al2O3 and LiOH⋅H2O, we systematically adjusted the lithium amount. It is found that because LiOH reacts preferentially with Al2O3, the amount of lithium reacting with the Ni0.5Co0.2Mn0.3(OH)2 precursor is reduced, which will reduce the electrochemical performance of the cathode material. The deterioration of the electrochemical properties of LiNi0.5Co0.2Mn0.3O2 cathode materials with insufficient lithium is mainly due to the transition of the material structure from a layered structure to a spinel structure. Moreover, the lithium supplemented samples show higher initial charge and discharge capacities, rate capabilities and cycling performances than the lithium un-supplemented samples.

A green synthesis strategy toward calcined calcium-aluminum layered double hydroxide with sludge as aluminum source for efficient removal of phosphate from water

Layered double hydroxides promise efficient phosphorus removal from water, yet their preparation process inevitably leads to the consumption of metal minerals and incurs high material costs. The drinking water treatment aluminum sludge with high aluminum content is a suitable source for obtaining metal aluminum. Recognizing the environmental and economic challenges in traditional layered double hydroxides production, this research proposes a novel approach utilizing high-aluminum drinking water treatment aluminum sludge as an alternative aluminum source. Herein, calcium-aluminum layered double oxides with aluminum sludge as aluminum source (Ca/(Al-DWTAS)-LDOs) were prepared by co-precipitation and calcination method. The study meticulously examines the influence of variables such as dosage, initial pH, and the presence of coexisting ions on phosphorus removal efficiency: at the optimal dosage (0.5 g/L), the adsorption efficiencies of Ca/(Al-DWTAS)-LDOs for phosphate in the range of 2.0 < pH < 11.0 and in the environment of common anionic disturbances were maintained at more than 90%. After six adsorption-desorption tests, the phosphate removal efficiency of Ca/(Al-DWTAS)-LDOs only decreased from 98.85% to 74.38%. According to the Sips isotherm model, the maximal adsorption capacity of Ca/(Al-DWTAS)-LDOs at ambient temperature (25 °C) was determined to be 110.14 mg/g. Adsorption mechanism of Ca/(Al-DWTAS)-LDOs were explored through characterization, kinetic and thermodynamic studies, mainly involving electrostatic reactions, ion exchange reaction, surface complexation reaction, and surface precipitation. When 0.5 g/L Ca/(Al-DWTAS)-LDOs was added to the actual swine wastewater with phosphate content of 37.25 mg/L, the phosphate removal efficiency reached 86.19%. This study not only provides an alternative process method for the acquisition of layered double hydroxides, but also has wide applications for environmental protection.

Optimization and characterization of sustainable geopolymer mortars based on palygorskite clay, water glass, and sodium hydroxide

Abstract The synthesis of ambient-cured sustainable geopolymer mortars (GMs) was studied throughout this work. To reduce carbon dioxide emissions, new materials must be used in the production of sustainable concrete and mortars. Many types of binders are used in the synthesis of GM and concrete (GPC), especially clay minerals. These clay minerals are considered sources of alumina and silica in GM and concrete. The geopolymerization process relies on the alkaline solution activating the alumino-silicate to produce geopolymer gel products. The palygorskite (PA) clay mineral, sodium hydroxide (NaOH), and sodium silicates (Na2SiO3) were chosen as a binder (solid material) and alkaline activator solution to synthesize GM at ambient temperature. PA was thermally treated at 550, 650, 700, and 750°C, respectively, to convert into high-reactive PA (HRP) HRP550, HRP650, HRP700, and HRP750, respectively. The characteristics of PA clay, HRP powders, and HRP-based GM were evaluated using compressive strength (CS) testing, X-ray fluorescence analysis, carbon footprint analysis, X-ray diffraction (XRD) diffractograms, Fourier transform infrared spectroscopy (FTIR) spectroscopy, scanning electron microscopy (SEM) images, and energy-dispersive X-ray spectroscopy (EDS) analysis. The maximum CS of 25.1 MPa was acquired for geopolymer synthesis utilizing HRP700-based GM cured at 30°C for 28 days. FTIR spectroscopy demonstrated that HRP-based GM showed the presence of Si–O, Al–O, and O–C–O bonds stretching vibrations in the alumino-silicate network. The results showed that the CO2 emissions had a reduction in the HRP-based GM compared with the reference mix of ordinary Portland cement mortar (OPM). The percentage of reductions was 14.1, 13.7, 13.1, and 12.4 for HRP550, HRP650, HRP700, and HRP750, respectively, compared with the OPM mixture. SEM images/EDS analysis and XRD diffractograms confirmed the presence of sodium alumino-silicate hydrates, magnesium silicate hydrate, and calcium silicate hydrate gels with high quantities particularly in the HRP700-based GM than that in HRP550, HRP650, and HRP750, respectively. The results indicate the suitability of HRP calcined at 700°C (HRP700) in the synthesis of the GM.

TEAOH-assisted cost-effective preparation of SSZ-13 using L zeolite as Al source

Developing an economical and high-efficiency synthesis pathway of SSZ-13 zeolite is of great significance for the ammonia selective catalytic reduction of nitrogen oxides (NH3-SCR of NOx) reactions. Herein, SSZ-13 zeolite were synthesized using L zeolite as the aluminum source in the presence of a mixed structure directing agent (SDA) composed of N,N,N, trimethtyl-1-adamantammonium hydroxide (TMAdaOH) and tetraethylammonium hydroxide (TEAOH). This synthesis strategy aims to accelerate the crystallization rate through interzeolite transformation, while less expensive TEAOH can play a cooperative structure-directing role, thus reducing the consumption of expensive TMAdaOH template. The results showed that pure SSZ-13 zeolites with high crystallinity can be obtained from L zeolite within 12 h at 160 ℃ under low TMAdaOH/SiO2 ratio of 0.05 (too low to carry out the synthesis on its own in the current synthesis system) in the presence of TEAOH. Moreover, the crystallization mechanism was also investigated by XRD, FT-IR, SEM and TG-DTG techniques. It was proposed that the crystallization of SSZ-13 occurs through the formation of SSZ-13 nuclei under the direction of TMAdaOH and promotion of TEAOH, subsequently TMAdaOH was incorporated in the framework to further induce the crystal growth of SSZ-13. Especially, the zeolite crystal size can be modulated by the amount of TEAOH added. In addition, After Cu2+ exchange, the obtained Cu-SSZ-13 sample exhibits superior catalysis performance in the NH3-SCR of NOx reaction, and the NOx conversion rate remained over 90 % across a broad range from 200 to 600 °C, demonstrating its significant application potentials in NOx removal from diesel vehicle exhausts.

Influence of in situ dysprosium aluminate garnet formation on sintering of reaction sintered magnesium aluminate spinel

AbstractIn the present study, commercially available different sources of magnesia and alumina were used to produce reaction sintered magnesium aluminate spinel (MgAl2O4). Initially, spinel with stoichiometric composition was prepared from three different sources of Al2O3 and two sources of MgO and then the effect of dysprosia (Dy2O3) in a concentration range of 1–4 wt.% on the sintered properties of spinels was studied in the temperature range of 1550–1650°C. The densities of the doped compositions were higher compared with the undoped ones, and the maximum density was found for the 1 wt.% Dy2O3‐doped samples. Phase analysis and microstructural studies revealed that formation of dysprosium aluminum garnet (Dy3Al5O12) phase along the intergranular positions, which served as grain‐growth inhibitors and improved densification. Further, 1 wt.% Dy2O3‐doped compositions also revealed better flexural strength and retained strength post thermal shock values than undoped spinel.

Wulff Constructions for an Equilibrium MFI-Type Zeolite Shape Modelling under Different Conditions

As an MFI-type zeolite, ZSM-5 zeolite has wide applications in industry, such as in the fine chemical, petrochemical, and coal chemical industries. However, shape control of ZSM-5 nanocrystals constitutes one of the major challenges of current nanotechnology. Here, the MFI framework structure was used as the theoretical model of pure silicon ZSM-5 to investigate the surface energy and Wulff shape. The models with different crystal surfaces were simulated by molecular dynamics (MD) with the assistance of machine learning potentials (MLPs). The factors influencing the crystal surface energy, such as temperature, pH, and ionic concentration, have been studied in detail. Depending on the calculated surface energies, the crystal surface morphology and its ratio were obtained by means of the Wulff theorem. The results show that the area in the equilibrium shape of the (110) surface is usually the largest, and its proportion varies with external conditions. A high temperature and high concentration of the aluminum source promoted the growth of the (110) crystal surface, and the theoretical value of the crystal surface ratio was as high as 90%. This study provides theoretical insight into the synthesis of zeolites with different morphologies of all-silicon or low-aluminum.

The effect of the preparation method of asphalt waste foam ceramic loaded Pd/Ce-P-Al2O3 coatings on their properties

Asphalt waste-based foam ceramics were prepared by organic foam impregnation, followed by ultrasound-assisted impregnation and calcination to deposit 3-5 wt.% Pd/Ce-P-Al2O3 active coatings. The results show that γ-Al2O3 as an aluminum source provides a higher specific surface area and facilitates the dispersion of the catalytic components, so that low-temperature conversion of CO can be achieved, but the coating uniformity, stability, and the ability to modify the defects on ceramic surfaces are lower than those of the aluminum nitrate calcination products. Aluminum dihydrogen phosphate as a P source could rapidly convert 60% of CO, but the performance decreased at a later stage, while phosphoric acid as a P source could achieve the complete conversion of CO at a lower temperature. The mechanical properties of the samples with the addition of aluminum dihydrogen phosphate and aluminum nitrate baked products were better, which was 0.6 MPa higher than the uncoated foam ceramics.

Unveiling the Influence of Varied Alumina Sources on Fresh Properties of Ordinary Portland Cement Mortar and Concrete: A Comprehensive Review

Unveiling the Influence of Varied Alumina Sources on Fresh Properties of Ordinary Portland Cement Mortar and Concrete: A Comprehensive Review