The aluminium industry is facing a challenge in meeting the goal of halved greenhouse gas emissions by 2050, while the demand for aluminium is estimated to increase 2–3 times by the same year. Energy ...efficiency will play an important part in achieving the goal. The paper's aim was to investigate possible production-related energy efficiency measures in the aluminium industry. Mining of bauxite and production of alumina from bauxite are not included in the study. In total, 52 measures were identified through a literature review. Electrolysis in primary aluminium production, recycling and general measures constituted the majority of the 52 measures. This can be explained by the high energy intensity of electrolysis, the relatively wide applicability of the general measures and the fact that all aluminium passes through either electrolysis or recycling. Electrolysis shows a higher number of emerging/novel measures compared to the other processes, which can also be explained by its high energy intensity. Processing aluminium with extrusion, rolling, casting (shape-casting and casting of ingots, slabs and billets), heat treatment and anodising will also benefit from energy efficiency. However, these processes showed relatively fewer measures, which might be explained by the fact that to some extent, these processes are not as energy demanding compared, for example, to electrolysis. In many cases, the presented measures can be combined, which implies that the best practice should be to combine the measures. There may also be a future prospect of achieving carbon-neutral and coal-independent electrolysis. Secondary aluminium production will be increasingly important for meeting the increasing demand for aluminium with respect to environmental and economic concerns and strengthened competitiveness. Focusing on increased production capacity, recovery yields and energy efficiency in secondary production will be pivotal. Further research and development will be required for those measures designated as novel or emerging.
•52 energy efficiency measures were identified in total.•Electrolysis, recycling and general measures comprised the majority of the measures.•In many cases, the presented measures can be combined.•There may be a future prospect for carbon-neutral and coal-independent electrolysis.•Secondary aluminium production and its energy efficiency will be pivotal.
Aluminium exposure is associated with bone disease (an elevated bone content of aluminium and reduced bone formation on bone biopsy) and neurotoxicity (features of altered brain functions and/or ...typical spike and slow wave waveforms on electroencephalogram) in patients with elevated blood aluminium concentrations.
To critically analyse the literature to determine the dose-toxicity relationships between aluminium exposure and related bone disease and aluminium neurotoxicity.
A systematic review of the literature with collation and analysis of individual data of human cases of aluminium exposure was conducted between 1 January 1966 and 30 December 2020. Embase, MEDLINE (OVID MEDLINE), PubMed and TOXNET were searched with the following strategies: "Aluminium AND toxicity OR aluminium AND poisoning OR aluminium AND dialysis OR aluminium AND chronic renal failure OR aluminium AND intravenous" limited to "(human)". Inclusion criteria required individual data relating to aluminium exposure in humans. Papers in which features of aluminium toxicity and analytical confirmation of aluminium exposure could not be determined in individual patients were excluded.
Thirty-seven papers were identified, which included data on 179 individuals exposed to aluminium. The sources of aluminium exposure (median duration of exposure) were: dialysis fluid (48 months) in 110 cases; oral aluminium hydroxide (20 months) in 20 cases; plasma exchange (2 months) in 16 cases; infant formula feed (minimal duration of 2 weeks) in 14 cases; intravesical exposures (2 days) in 13 oncology patients and potable water exposure in six cases.
Of the 110 patients exposed to dialysis fluid, 99 were adults and 11 children, who were analysed separated. Of the adults, 50 with aluminium neurotoxicity had a median aluminium concentration of 467 µg/L (IQR 230 − 752), 28 with aluminium bone disease had a median aluminium concentration of 142 µg/L (IQR 46-309) and 21 with asymptomatic aluminium overload had a median aluminium concentration of 35 µg/L (IQR 26-51). Median aluminium concentrations were significantly greater in patients with aluminium neurotoxicity compared to those with aluminium bone disease (p < 0.0001) or asymptomatic aluminium overload (p < 0.0001).
Of the 20 cases, 11 were adults and nine were children. Of the 11 adults, eight with aluminium neurotoxicity had a median aluminium concentration of 682 µg/L (IQR 438-770) and three with aluminium bone disease had a median aluminium concentration of 100 µg/L (IQR 62-138) (p = 0.007). Of the nine children, five had aluminium neurotoxicity with a median aluminium concentration of 335 µg/L (IQR 229-601), one had aluminium bone disease and an aluminium concentration of 1030 µg/L and three had asymptomatic aluminium overload with a median aluminium concentration 98 µg/L (IQR 65-365).
Three patients with stage 5 chronic kidney disease developed aluminium bone disease during plasma exchange; their median blood or serum aluminium concentration was 73 µg/L (IQR 59-81). Asymptomatic aluminium overload was reported in six patients receiving outpatient plasma exchange who had a median creatinine clearance of 71 mL/min (IQR 40-106) and a median aluminium concentration of 49 µg/L (IQR 34-116), and in seven intensive care patients with acute kidney injury whose median aluminium concentration was 30 µg/L (IQR 17-35); (p = 0.02).
All 13 intravesical exposures developed aluminium neurotoxicity and had a median aluminium concentration of 157 µg/L (IQR 45-276).
All six patients developed aluminium bone disease and their median blood aluminium concentration was 17 µg/L (IQR 13-100).
Toxic aluminium exposure can result in neurotoxicity and bone disease, especially in patients with chronic kidney disease. Adults with stage 5 chronic kidney disease chronically exposed to aluminium developed aluminium neurotoxicity at higher concentrations than those with aluminium bone disease or with asymptomatic aluminium overload. Aluminium neurotoxicity was reported at lower concentrations following acute exposure to intravesical aluminium. Extrapolating the relevance of these concentrations to the general population is problematic in that the data were derived from oncology patients, however, the possibility that aluminium neurotoxicity may occur at concentrations lower that those reported historically in patients with stage 5 chronic kidney disease cannot be excluded.
In the present study, aluminium metal matrix composites (AMCs) were successfully produced through stir-squeeze casting using a novel approach. The feasibility of using car scrap aluminium alloy ...wheels (SAAWs) as the matrix material and spent alumina catalyst (SAC) from oil refineries as reinforcement material was investigated. For the purpose of comparision, composites were also produced using AlSi7Mg (LM25 grade) aluminium alloy as a matrix and alumina as reinforcement particles through the stir-squeeze casting process. In total, four different combinations of composites (AlSi7Mg + alumina; scrap aluminium alloy + alumina; AlSi7Mg + spent alumina catalyst; scrap aluminium alloy + spent alumina catalyst) were produced and characterized. Microstructural investigations using an optical microscope and a scanning electron microscope (SEM) as well as energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) revealed that in all four composites the reinforcement formed a mixture in the eutectic silicon phase of the matrix alloy. The alumina particles' size and content ratio greatly influenced this mixture's formation and morphology. The composites produced using alumina exhibited smaller pore sizes and lower porosity as compared to the composites produced with a spent alumina catalyst. Superior mechanical properties were also obtained when using alumina as reinforcement, and better mechanical properties can mainly be attributed to the morphology of the reinforcement and silicon eutectic phase mixture. The scrap aluminium alloy + alumina exhibited the lowest porosity (7.3%) and abrasive wear loss (0.11 mg for the finest abrasive), highest hardness (58.5 BHN), and second highest ultimate tensile strength (UTS) (125 MPa) and ultimate compressive strength (UCS) (312 MPa) among the four composites.
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•A novel approach used to produce metal matrix composites from waste materials.•The alumina reinforcement combines with the eutectic silicon to form a mixture.•Acicular, blunted, needle-like mixture morphology improves mechanical properties.•Enhanced ultimate tensile (125 MPa) and compressive strength (312 MPa) obtained.
•COD and Cr(III) species can be simultaneously removed by electrocoagulation.•Cu-containing Al alloy is more efficient than pure Al as electrodes.•Dilution of too concentrated tannery wastewater is ...required for efficient treatment.
This paper deals with the ability of electrocoagulation (EC) to remove simultaneously COD and chromium from a real chrome tanning wastewater in a batch stirred electro-coagulation cell provided with two aluminium-based electrodes (aluminium/copper/magnesium alloy and pure aluminium). Effects of operating time, current density and initial concentration of Cr(III) and COD have been investigated. The concentrations of pollutants have been successfully reduced to environmentally acceptable levels even if the concentrated effluent requires a long time of treatment of around 6h with a 400A/m2 current density. The aluminium alloy was found to be more efficient than pure aluminium for removal of COD and chromium. Dilution of the waste has been tested for treatment: high abatement levels could be obtained with shorter time of treatment and lower current densities. Energy consumption of the electrocoagulation process was also discussed. The dilution by half of the concentrated waste leads to a higher abatement performance of both COD and chromium with the best energy efficiency.
The paper presents a comprehensive review on dissimilar friction stir welding (FSW) of Al to non-Al metallic materials, wherein the combination of Al–Mg, Al–Cu, Al-steel and Al–Ti are covered. The ...summary revealed that FSW is observed as one of the most feasible solutions in the family of welding in case of dissimilar materials combinations of Al to non-Al metallic materials. The challenges such as the formation of intermetallic compounds, defects, and degradation of mechanical properties at the joint area are extensively managed in the case of dissimilar FSW compared to dissimilar conventional welding.
•The present work focuses on FSW of different Al to Non-Al metallic materials.•The different Al to Non-Al metallic materials is Al–Ti, Al-steel, Al–Cu, and Al–Mg.•The effect of process parameters on material flow and heat generation is also discussed.•Influential factors like tool material selection, tool design, and joint configuration are also covered.•The microstructural and mechanical property of each material combination is explained in detail.
Aluminium toxicity may act in two distinct ways, depending on the level of contamination. Relatively low aluminium levels from environmental origin (mainly from drinking water poor in silica) have ...been shown to be statistically associated with senile dementias of Alzheimer type (chronic intoxication). In addition, high aluminium therapeutic levels (from phosphate binders, antacids, …) can induce different, more rapid, symptoms (acute intoxication). In all cases, aluminium toxicity is largely conditioned by aluminium bioavailability, which in turn hinges upon aluminium coordination chemistry in vivo. The highly polarising power of the Al
3+ ion dictates its particular affinity for oxygen donors that abound in essential biomolecules and dietary substances. The influence of these substances on aluminium bioavailability, metabolism and toxicity can be assessed through animal models. However, understanding the mechanisms through which aluminium–ligand interactions may influence physiological processes on the molecular level requires a knowledge of the speciation of the metal in the main biofluids. Access to this critical information can a priori be gained through direct experimental analysis of relevant biological samples. It is in this way that aluminium protein-bound fractions, involving essentially transferrin, have been identified, but using such a direct approach to analyse the ultrafiltrable pool of the metal is a virtually insurmountable task, hence the necessity to have recourse to computer-aided speciation techniques based on simulation models. Following a previous review published in this journal on nearly the same topic Coord. Chem. Rev. 149 (1996) 241, this article updates the knowledge available on both biological and chemical fronts. After a review of experimental investigations led on the roles of aluminium–ligand interactions in aluminium bioavailability, metabolism and toxicity, contributions of experimental and computer-aided speciation to the understanding of the relevant processes are then analysed. Significant progress has been made in the diverse aspects of the biological field, in particular, in relation to the role of dietary ligands on aluminium gastrointestinal absorption, excretion and tissue distribution. Also, very intensive research has been pursued on the design of new aluminium sequestering agents to treat acute intoxications. Some progress has also been made on the chemical side relative to computer-aided speciation applications to gastrointestinal and blood plasma conditions. However, the gap is increasing between the large body of observations made by physiologists and toxicologists and the few data painfully obtained by coordination chemists to interpret the relevant phenomena.
Recently, aluminium scandium nitride (AlScN) emerged as a material with superior properties compared to aluminium nitride (AlN). Substituting Al with Sc in AlN leads to a dramatic increase in the ...piezoelectric coefficient as well as in electromechanical coupling. This discovery finally allowed us to overcome the limitations of AlN thin films in various piezoelectric applications while still enabling us to benefit from all of the advantages of the parent material system, such as a high temperature stability, CMOS compatibility, and good mechanical properties. Potential applications include RF filters (bulk acoustic wave (BAW) or surface acoustic wave (SAW) resonators), energy harvesting, sensing applications, and infra-red detectors. The recent progress in MOCVD- and MBE-grown AlScN has led to high-frequency and -power electronics, (high-electron-mobility transistors (HEMTs)). AlScN is the first wurtzite III-nitride where ferroelectric switching was observed, allowing for many new possible applications in semiconductor memories additionally, it enables the additional functionality of switching to applications where piezoelectric materials are already in use. This Special Issue was very successful in covering all of the main aspects of AlScN research, including its growth, the fundamental and application-relevant properties, and device fabrication and characterization. We can see that AlScN technology is mature enough to be utilized in wafer-level material development and complicated devices, but there is still much to discover in terms of deposition process control, anisotropy, and, in particular, ferroelectric behavior.
Oxidation of A356 aluminum alloy at molten state is investigated from thermogravimetric analyses. Linear kinetics followed by unexpected logarithmic kinetics is observed during the oxidation process. ...Scanning electron microscopy imaging coupled with wavelength‐dispersive X‐ray spectroscopy analyses reveal a heterogeneous oxide layer composed of spinel (MgAl2O4) embedded in a nonoxidized alloy matrix. Nonlinear diffusion of magnesium through the heterogeneous oxide layer is the key mechanism proposed to explain the logarithmic kinetics. The growth of spinel phase causes a growing complexification of the aluminum network through which magnesium is diffusing. To model the magnesium transport through the oxide layer, an effective diffusion coefficient, build from the pioneering approach developed by Davies et al. (Davies, D., Evans, U. & Agar, J. (1954) Proc. Roy. Soc. London. A., 225, 443), is introduced in the Deal–Grove model.
The genetic predispositions which describe a diagnosis of familial Alzheimer’s disease can be considered as cornerstones of the amyloid cascade hypothesis. Essentially they place the expression and ...metabolism of the amyloid precursor protein as the main tenet of disease aetiology. However, we do not know the cause of Alzheimer’s disease and environmental factors may yet be shown to contribute towards its onset and progression. One such environmental factor is human exposure to aluminium and aluminium has been shown to be present in brain tissue in sporadic Alzheimer’s disease. We have made the first ever measurements of aluminium in brain tissue from 12 donors diagnosed with familial Alzheimer’s disease. The concentrations of aluminium were extremely high, for example, there were values in excess of 10μg/g tissue dry wt. in 5 of the 12 individuals. Overall, the concentrations were higher than all previous measurements of brain aluminium except cases of known aluminium-induced encephalopathy. We have supported our quantitative analyses using a novel method of aluminium-selective fluorescence microscopy to visualise aluminium in all lobes of every brain investigated. The unique quantitative data and the stunning images of aluminium in familial Alzheimer’s disease brain tissue raise the spectre of aluminium’s role in this devastating disease.
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