Acidic Alumina Research Articles

Side-Reactions of Polyvinylidene Fluoride and Polyvinylidene Chloride Binders with Aluminum Chloride-Based Ionic Liquid Electrolyte in Rechargeable Aluminum-Batteries

Rechargeable aluminum batteries (RABs) use a Lewis acidic aluminum chloride (AlCl3) and 1-Ethyl-3-methylimidazolium chloride (EMImCl) ionic liquid electrolyte. Electrode fabrication often relies on procedures from lithium-ion batteries (LIBs), including the use of Polyvinylidene fluoride (PVdF) as a binder. However, PVdF reacts with Al2Cl7 − in the RAB electrolyte, making it unsuitable for new battery types. The literature lacks details on the products formed, changes in the ionic liquid electrolyte, and the implications for electrochemical performance. With potential European Chemical Agency restrictions on per- and polyfluoroalkyl substances (PFAS) by 2025, Polyvinylidene chloride (PVdC) is being explored as an alternative binder. In contact with AlCl3:EMImCl (1.50:1.00) electrolyte, both, PVdF and PVdC transform into amorphous carbon during dehydrofluorination and dehydrochlorination, respectively, as confirmed by Raman spectroscopy. Furthermore, via 19F-NMR, it is shown that the reaction time between the soaked polymers and the ionic liquid has a significant influence on the newly formed aluminum chlorofluoride complexes. Electrochemical tests of graphite-based electrodes indicate increasing specific capacity of PVdF compared to PVdC with a continuous number of cycles. Amorphous carbon can prevent the disintegration of graphite and enhance conductivity. Furthermore, newly formed AlF4 − can run a co-intercalation and lead to increasing specific capacity.

Investigation on preparation and properties of gel type 188W/188Re generator

As one of the most important integrated nuclides for diagnosis and treatment in recent years, rhenium-188 (188Re) has a broad scope in the clinical application. Due to the specific properties of such radionuclide, it was mainly provided by the chromatographic 188W-188Re generators. There is no doubt that the application of 188Re in the treatment of various diseases depended on the development of 188W-188Re generator. Considering the high standards of such technology on radioactive activity of 188W and impurity content, a 188W-188Re generator filled with the zirconium tungstate gel has been prepared in this work. The effects of molar ratio of chemical agents, pH, reaction temperature, drying methods, rinsing methods and other conditions on the synthesis of gel particles have been studied. Furthermore, a variety of characterization techniques were used to observe the macro-/micro-morphology and chemical structure of gel particles. It can be concluded that vacuum freeze-dried method could significantly increase the specific surface area, pore size and tungsten content of gel particle. In order to decrease the content of 188W in the elute, a handful of acidic alumina was filled in the bottom of our 188W-188Re generator, an elution and purification integrated-generator was formed. During the first five processes, the nuclear purity of 188Re solution was above 99.99%, the radiochemical purity was approximately 99.5%, the pH value was 5.0–7.0 and the average elution efficiency reached up to 82.7%. In addition, the leakage rate of 188W was low as 1.60 × 10−6, and the peak of elute curve was located at 2 mL without the trailing phenomenon. This work lays a solid foundation for the domestic demand of daughter nuclide 188Re, further makes an outstanding contribution to the application of the radiation therapy technology and the protection of people's health.

Additive manufacturing of alumina refractories by binder jetting

In this work, refractory components based on alumina were produced by binder jetting using a large-scale 3D printer. The formulation contained several particle fractions up to a grain size of 3 mm, equal to the printer resolution. The binder system contained fine dead burnt magnesia, milled citric acid and reactive alumina, which were added to the aggregate mixture to create the powder bed. Deionized water was deposited from the printer's nozzles and triggered the binding reaction between the magnesia and citric acid. After 24 h, the printed samples were removed from the powder bed, dried and sintered at 1600 °C for 5 h. Reactive alumina contributed to the in situ creation of magnesium aluminate spinel at high temperature. The samples were characterized in terms of Young's modulus of elasticity, bending and compressive strength in 2 directions (parallel and perpendicular to the printing direction). The broken parts were used to investigate physical properties such as the open porosity and bulk density. The microstructure was studied by means of computed tomography. Finally, powder samples were used to determine the phase composition at different stages of production by means of XRD.

Role of electrode temperature in anodic growth of sulfuric acid alumina films

Role of electrode temperature in anodic growth of sulfuric acid alumina films

Catalytic Synergy between Lewis Acidic Alumina and Pt in Hydrodechlorination for Plastic Chemical Recycling.

Pyrolysis-based plastic chemical recycling has gained significant industrial attention due to its advantage of eliminating complex plastic sorting processes. However, plastic pyrolysis oil contains various components that require stringent removal before subsequent processes. In particular, Cl compounds originating from the decomposition of poly(vinyl chloride) can cause serious corrosion of reactors and catalyst deactivation in downstream processes. While extensive research has been conducted on the removal of other heteroatoms (S, N, and O) from organic compounds via hydrotreating, studies on the removal of Cl have been scarce. In this study, hydrodechlorination over Pt catalysts on various supports is comprehensively investigated using 1,2-dichloroethane as a model reactant. Our results demonstrate that Pt on γ-Al2O3 can exhibit exceptionally high catalytic activity compared to those on other supports due to a distinct bifunctional mechanism. Rigorous studies reveal that the Lewis acidic pentacoordinated Al sites of γ-Al2O3 activate C-Cl bonds, whereas Pt activates H2 and provides spillover H to remove Cl as HCl. The bifunctional mechanism enables the minimized use of precious Pt (<0.1 wt %) to achieve high activity. Pt/γ-Al2O3 also allows for efficient Cl removal (96.8%) with high stability in treating waste plastic pyrolysis oil containing 7500 ppm of Cl.

Response surface methodology and experimental evaluation of the inhibitory properties of corn leaf extract for aluminum corrosion in acid media

PurposeThis study aims to develop eco-friendly corrosion inhibitors for aluminum in acidic media by evaluating the corrosion inhibition properties of corn leaf extract (CLE) using response surface methodology (RSM) and experiments.Design/methodology/approachThe RSM was combined with experiments to evaluate the corrosion inhibition properties of CLE on aluminum in acid media.FindingsThe effectiveness of the inhibition increased with increasing inhibitor concentration and time but decreased with increasing temperature. The corrosion inhibition mechanism revealed the corrosion process is spontaneous exothermic physical adsorption. Thermodynamic parameters revealed an activation energy between 32.1 and 24.7 kJ/mol, energy of adsorption between −14.53 and −65.07 and Gibbs free energy of −10.12 kJ/mol which indicated the CLE exothermically spontaneously physisorbed. A model was generated to estimate the effect of the process parameters (inhibitor concentration, reaction time and temperature) using the RSM. Optimization of the process factors was also carried out using the RSM. The percentage inhibition efficiency obtained experimentally (85.61%) was closely comparable to 84.89% obtained by the theoretical technique (RSM). The SEM observations of the inhibited and uninhibited Al samples demonstrated that CLE is an effective corrosion inhibitor for aluminum in acid media.Originality/valueResults herein provide novel information on the possible application of CLEs as effective eco-friendly corrosion inhibitors.

Reaction mechanism, hygroscopic behavior, and properties of aluminum phosphate adhesive

The lack of basic research is a principal reason restricting the widespread application of aluminum phosphate adhesive, such as its reaction mechanism is not yet clear. Herein, we investigate the dissolution behavior of aluminum oxide (Al2O3) in acid aluminum phosphate (AAP) solution and the effects of Al2O3 addition, calcination temperature and phosphorus to aluminum (P/Al) ratio of the AAP solution on the thermal evolution, phase development and hygroscopic behavior of aluminum phosphate adhesive. The dissolution process of Al2O3 in AAP solution is controlled by external diffusion. The thermal evolution of aluminum phosphate adhesives is a complex process that is a function of Al2O3 addition and calcination temperature. Although it is a linear process, many of the reactions are largely coupled and occur simultaneously. The hygroscopic mechanism of aluminum phosphate adhesives is associated to the hydrophilicity of the hydroxyl groups (P–OH). Increasing the calcination temperature and the Al2O3 addition can improve the hygroscopicity resistance properties. Finally, the mechanical and dielectric properties of the quartz fiber cloth reinforced aluminum phosphate matrix composites (SiO2f/aluminum phosphate composites) were also investigated. The results demonstrate that the composites have the characteristics of light weight, high strength, and excellent dielectric properties, suggesting that they have attractive applications in radome materials.

Bipolar pulse anodizing of aluminum: Understanding the fundamental electrochemical mechanisms

Anodic aluminum oxides (AAO) with attractive morphological properties might be obtained by pulse anodizing via controlled hydrogen release during the cathodic step. In order to enhance such processes currently relying on empirical studies, the present paper aims to investigate basically the AAO formation on pure aluminum in sulfuric acid during a bipolar pulse anodizing process, by combining in situ electrochemical measurements and cross-section scanning electron microscopy. Results show that the hydrogen evolution at the metal/oxide interface during the cathodic step can be easily managed by current control. Actually, under cathodic galvanostatic conditions, successive mechanisms occur, depending on both the duration and the current density: a first stage corresponds to the reorganization of the electric charges and the migration of H+ through the AAO barrier layer and is followed by hydrogen evolution at the metal/oxide interface, which induces the formation of local or more extended defects at the metal/oxide interface until the detachment of the AAO layer.

High precision polishing of aluminum alloy mirrors through a combination of magnetorheological finishing and chemical mechanical polishing

After the aluminum alloy mirror machined by single point diamond turning (SPDT), the residual tool marks and surface accuracy of the aluminum alloy mirror cannot meet the requirements of visible or ultraviolet light system. In this study, a processing method combining magnetorheological finishing (MRF) and chemical mechanical polishing (CMP) is proposed to realize the polishing of aluminum alloy mirrors with high efficiency, high precision and high-quality. Firstly, the properties and composition of passivation layer after MRF were analyzed and the polishing performance of acidic, neutral and alkaline alumina polishing fluid on passivation layer were investigated based on the computer numerical control (CNC) polishing equipment. Based on the experimental results, a new acidic nano-silica polishing fluid which is suitable for the efficient and high-quality removal of passivation layers on aluminum alloy surfaces was developed. Finally, a combined approach of MRF-CMP was used to the directly polishing of a rapidly solidified aluminum mirror (RSA-6061) with a diameter of 100 mm after SPDT. With two iterative of MRF-CMP polishing in 220 minutes, the surface accuracy of the aluminum alloy mirror was improved from 0.1λ (λ=632.8 nm) to 0.024λ, and the surface roughness (Ra) decreased from 3.6 nm to 1.38 nm. The experiment results manifest that high precision, and high-quality aluminum alloy mirror can be achieved by MRF-CMP method with the new developed acid nano-silica polishing fluid and suitable MR polishing fluid. The research results will provide a new strategy for ultra-precision direct polishing of aluminum alloy mirrors and will also give the important technical support for the extensive use of aluminum alloy mirror in visible light and ultraviolet optical systems.

Sorption behavior of Molybdenum (IV) onto commercial acidic alumina surface

Sorption behavior of Molybdenum (IV) onto commercial acidic alumina surface

Communication—Anodization of Aluminum in Phosphoric Acid Containing Glycerol at 30 °C

Aluminum was anodized in a phosphoric acid solution containing glycerol. Anodization in high concentration and high temperature electrolytes typically faces challenges due to the chemical dissolution of the anodic film. However, we found that the maximum attainable film thickness could be doubled by incorporating glycerol into the electrolyte. This enhancement was more effective under conditions of high concentration and temperature than in environments with lower concentrations and temperatures.

Selection and Validation of Reference Genes in Sudan Grass (Sorghum sudanense (Piper) Stapf) under Various Abiotic Stresses by qRT-PCR.

Quantitative reverse transcription PCR (qRT-PCR) can screen applicable reference genes of species, and reference genes can be used to reduce experimental errors. Sudan grass (Sorghum sudanense (Piper) Stapf) is a high-yield, abiotic-tolerant annual high-quality forage with a wide range of uses. However, no studies have reported reference genes suitable for Sudan grass. Therefore, we found eight candidate reference genes, including UBQ10, HIS3, UBQ9, Isoform0012931, PP2A, ACP2, eIF4α, and Actin, under salt stress (NaCl), drought stress (DR), acid aluminum stress (AlCl3), and methyl jasmonate treatment (MeJA). By using geNorm, NormFinder, BestKeeper, and RefFinder, we ranked eight reference genes on the basis of their expression stabilities. The results indicated that the best reference gene was PP2A under all treatments. eIF4α can be used in CK, MeJA, NaCl, and DR. HIS3 can serve as the best reference gene in AlCl3. Two target genes (Isoform0007606 and Isoform0002387) belong to drought-stress-response genes, and they are highly expressed in Sudan grass according to transcriptome data. They were used to verify eight candidate reference genes under drought stress. The expression trends of the two most stable reference genes were similar, but the trend in expression for Actin showed a significant difference. The reference genes we screened provided valuable guidance for future research on Sudan grass.

The role of the oxide layer in the corrosion of aluminium in acidic solutions

AbstractThe role of the oxide layer in the corrosion of aluminium in hydrochloric, sulphuric(VI) and orthophosphoric acid is studied at pH 1. The oxide layer is stable in hydrochloric and sulphuric acids. The corrosion rate of aluminium in these solutions is 0.2 and 0.3 mm/year, respectively. The oxide layer is unstable in orthophosphoric acid and the corrosion rate is higher, 1.75 mm/year. The corrosion process is studied using scanning electron microscopy, immersion and electrochemical techniques. The mechanism of corrosion of aluminium in the orthophosphoric acid solution is proposed. It includes the adsorption of a reaction intermediate on the surface of the corroding metal and the formation of the oxide layer at anodic potentials with respect to the open‐circuit potential. It is also explained when the inductive loop appears on the electrochemical impedance spectra of aluminium corroding in orthophosphoric acid solution. The mechanism of aluminium corrosion in hydrochloric and sulphuric acid is more complex compared to orthophosphoric acid, and is not analysed in detail.

Tough and adhesive conductive hydrogels with fast gelation from a polyphenol–aluminium ion dual self-catalysis system for wearable strain sensors and triboelectric nanogenerators

A tough and adhesive conductive double network hydrogel (PVA/PHEAA–TA–Al3+ gel) was prepared via rapid in situ room temperature gelation processes (25 °C, 215 s) in a tannic acid–aluminium ion (TA–Al3+) dual self-catalysis system.

Technological analysis of liquid waste parameters in treatment system for phosphorus production

This study considers the problem of analyzing a complex hierarchical system of phosphorus production wastewater treatment, which is characterized by considering the process of sedimentation of elemental phosphorus sludge particles and mechanical impurities. The study presents a framework for decision-making on the purification of wastewater from phosphorus production, which is contaminated with toxic impurities and must meet sanitary norms. The framework considers the reagents introduced, as well as the increased mineralization of water, which cannot be discharged into the water body for ecological reasons. Instead, it is reused in production. It is demonstrated that for mechanical treatment of sewage from elemental phosphorus and suspended solids, as well as to improve sedimentation of particles, iron sulphate is used as a coagulant. The action of this coagulant is similar to that of sulphuric acid aluminum, which is widely used for water treatment. Thus, a complex engineering approach is presented for a complex system of phosphorus production wastewater treatment.

Metabolic adaptations of Pinus massoniana to low phosphorus and acidic aluminium with or without ectomycorrhization

Phosphorus (P) deficiency and aluminium toxicity often coexist and are the major constraints hampering plant growth in acidic soils. Plants have evolved several strategies to cope with these adverse environments, including the recruitment of beneficial microbes, especially mycorrhizal fungi. By employing microscopic observation, histochemical staining, and UPLC-MS/MS techniques, we analyzed the aluminium deposition and cell viability of root, symbiotic process with ECM fungus Suillus bovinus, as well as the metabolic adjustments in Pinus massoniana under low P and/or acidic aluminium conditions. The formation process of mycorrhizae between P. massoniana and S. bovinus was not affected by low P and acidic aluminium treatments, but low P postponed the development of mantle and Hartig nets. The colonization rate increased in the presence of acidic aluminium, and S. bovinus inoculation improved root cell viability and promoted the growth of P. massoniana under low P and/or acidic aluminium conditions. The metabolic responses of nonmycorrhizal and mycorrhizal P. massoniana to low P and/or acidic aluminium were different. Low P and/or acidic aluminium significantly increased the accumulation of phenolic acids and altered starch and sucrose metabolism in roots of nonmycorrhizal P. massoniana. However, for mycorrhizal P. massoniana, low P and/or acidic aluminium treatments increased the organic acids content of shared differentially accumulated metabolites (DAMs). Furthermore, acidic aluminium mainly altered arginine and proline metabolism, and phenylalanine metabolism was affected under low P conditions, linoleic acid metabolism was changed under the combined treatment of low P and acidic aluminium in mycorrhizal P. massoniana. These findings enhance our comprehension of how ECM fungi assist P. massoniana in coping with P deficiency and aluminium toxicity in acidic environments and provide a theoretical basis for ECM fungal application during seedling cultivation in acidic soils.

Destabilization mechanism of acid aluminum phosphate solution: Effects of P/Al ratio, concentration and boron doping

The poor long-term stability of acid aluminum phosphate (AAP) solutions limits their industrial application. To understand its destabilization mechanism, the effects of phosphorus to aluminum ratio, concentration, and boron doping on the stability of the AAP solution are investigated. The destabilization mechanism involves polymerizing the aluminum phosphate species to form insoluble aluminum phosphate compounds. The solution concentration controls the polymerization kinetics, and reducing the concentration can improve the stability of the AAP solution. Boron introduction improves solution stability by reducing the number of active sites on the aluminum phosphate species available for polymerization and by increasing solution viscosity to restrict the movement of the aluminum phosphate species.

Rapid Polyolefin Hydrogenolysis by a Single-Site Organo-Tantalum Catalyst on a Super-Acidic Support: Structure and Mechanism.

The novel electrophilic organo-tantalum catalyst AlS/TaNpx (1) (Np=neopentyl) is prepared by chemisorption of the alkylidene Np3 Ta=CHt Bu onto highly Brønsted acidic sulfated alumina (AlS). The proposed catalyst structure is supported by EXAFS, XANES, ICP, DRIFTS, elemental analysis, and SSNMR measurements and is in good agreement with DFT analysis. Catalyst 1 is highly effective for the hydrogenolysis of diverse linear and branched hydrocarbons, ranging from C2 to polyolefins. To the best of our knowledge, 1 exhibits one of the highest polyolefin hydrogenolysis activities (9,800 (CH2 units) ⋅ mol(Ta)-1 ⋅ h-1 at 200 °C/17 atm H2 ) reported to date in the peer-reviewed literature. Unlike the AlS/ZrNp2 analog, the Ta catalyst is more thermally stable and offers multiple potential C-C bond activation pathways. For hydrogenolysis, AlS/TaNpx is effective for a wide variety of pre- and post-consumer polyolefin plastics and is not significantly deactivated by standard polyolefin additives at typical industrial concentrations.

Rapid Polyolefin Hydrogenolysis by a Single‐Site Organo‐Tantalum Catalyst on a Super‐Acidic Support: Structure and Mechanism

AbstractThe novel electrophilic organo‐tantalum catalyst AlS/TaNpx (1) (Np=neopentyl) is prepared by chemisorption of the alkylidene Np3Ta=CHtBu onto highly Brønsted acidic sulfated alumina (AlS). The proposed catalyst structure is supported by EXAFS, XANES, ICP, DRIFTS, elemental analysis, and SSNMR measurements and is in good agreement with DFT analysis. Catalyst 1 is highly effective for the hydrogenolysis of diverse linear and branched hydrocarbons, ranging from C2 to polyolefins. To the best of our knowledge, 1 exhibits one of the highest polyolefin hydrogenolysis activities (9,800 (CH2 units) ⋅ mol(Ta)−1 ⋅ h−1 at 200 °C/17 atm H2) reported to date in the peer‐reviewed literature. Unlike the AlS/ZrNp2 analog, the Ta catalyst is more thermally stable and offers multiple potential C−C bond activation pathways. For hydrogenolysis, AlS/TaNpx is effective for a wide variety of pre‐ and post‐consumer polyolefin plastics and is not significantly deactivated by standard polyolefin additives at typical industrial concentrations.

The effect of acidic–basic structural modification of nickel-based catalyst for ammonia decomposition for hydrogen generation

The utilization of non-precious nickel-based catalyst in increasing ammonia dissociation for COx-free hydrogen production was investigated. Typically, Co, La and basic metal oxides (Na, K, Ba) promoters were synthesized with nickel over acidic gamma alumina support. The main objective of the study was to modify the acid-base surface of catalyst structure thereby increasing ammonia dissociation activity. The catalytic activity for ammonia decomposition was strongly influenced by the addition of Na and K oxide promoters over 15 %Ni/Al2O3 resulting in moderate-stronger basic sites suitable for ammonia conversion. The addition of Na and K oxides showed a clear trend in tuning the trimetallic catalyst and significantly reducing the amount of strongly adsorbed hydrogen on the catalyst surface. This results in higher ammonia conversion which increased as a function of temperature to 32.4 %, 67.5 % and 95.3 % at 430 ᵒC, 485 ᵒC, and 533 ᵒC, respectively. Ammonia conversion using promoters was stable with no degradation of performance and the conversion increased with the decrease in WHSV. The catalytic reactivity over trimetallic catalysts was systematically influenced by their basic-acidic property that promoted ammonia dehydrogenation on the surface of nickel oxide-based catalyst.