Soluble Aluminum Research Articles

The influence of complexing agents on the solubility and absorption of aluminium in rats exposed to aluminium in water

The influence of complexing agents on the solubility and absorption of aluminium in rats exposed to aluminium in water

The influence of complexing agents on the solubility and absorption of aluminium in rats exposed to aluminium in water

The influence of citrate (0–31mm), fluoride (0 or 2.6mM) and silicate (0 or 2.6mM) on the absorption of Al (0–18mM) was studied in rats. We tested the hypothesis that the solubility and absorption of Al increases in the gastrointestinal (GI) tract in the presence of the complexing agents. Male rats were exposed for 6 or 7 weeks to soluble Al in acidic drinking water (pH 2.5–3.0) with or without the complexing agents. At the end of exposure Al was fractionated in the stomach content, in order to study if the solubility of Al was changed after ingestion. Al absorption was estimated by Al analysis of the right femur bone. Speciation calculations indicated that citrate and fluoride caused formation of soluble Al-citrate (97%) and -fluoride (>60%) complexes in the water. Silicate did not affect the theoretical speciation. In all cases, a large fraction of soluble Al became insoluble in the stomach after ingestion. The concentration of soluble Al increased only in the presence of citrate or a mixture of fluoride and silicate, but citrate was the only complexing agent that influenced the absorption of Al in the rat. This indicates that the form of Al may be changed in the GI tract when soluble drinking-water Al is ingested, and that the solubility of Al in drinking water and GI tract may not be good predictors of the bioavailability of Al even when chelating agents are present.

SON 68 nuclear glass alteration kinetics between pH 7 and pH 11.5

The effect of the pH was investigated on the mechanisms of SON 68 (R7T7-type) glass alteration under `saturation' conditions in order to delimit the pH range within which a stable, protective gel is formed. Static experiments were conducted at 90°C with an S/ V ratio of 50 cm −1 at various imposed pH values: 7, 8, 9.5, 10, 10.5, 11 and 11.5. An additional experiment was conducted with no restriction on the pH. The kinetic study showed that a protective gel formed in all the test media, although its stability was pH-dependent: at pH 11 or higher, the precipitation of a potassium and sodium aluminosilicate led to the degradation of the gel and the lose of its protective properties. This phenomenon resulted in renewed glass alteration, leading to complete and rapid degradation of the glass into alteration products. The aluminosilicate precipitation was found to be limited by the solubility of aluminum. Below pH 10, this type of secondary phase is unlikely to precipitate and the gel should remain stable. This study, based on thermodynamic and kinetic considerations, suggests that aqueous alteration of the French SON 68 nuclear glass results in the formation of a protective gel with long-term stability between pH 7 and pH 10.

Effect of aluminum substitution and rare-earth content on the structure of R 2(Fe 1− xAl x) 17 (R=Tb, Dy, Ho, Er) phases

The phase equilibria in the iron rich parts of the R–Fe–Al (R=Tb, Dy, Ho, Er) phase diagrams at 500°C have been studied by X-ray powder diffraction analysis. As the aluminum contents in the series R 2(Fe 1− x Al x ) 17 are increased the hexagonal Th 2Ni 17 type structure (or a substitution derivative of that structure) transforms — usually via a hexagonal TbCu 7 type derivative structure — into the rhombohedral Th 2Zn 17 type structure (or a substitution derivative of that structure). The hexagonal structures dominate at or below the molar ratio R/(Fe,Al)=2/17 (10.5 and 9.5 at.% R), while the rhombohedral structure dominates at higher R contents (11.5 at.%). The solubility of aluminum in the hexagonal structure increases as the atomic size of R decreases (from x=0–3.42 in Tb 2Fe 17− x Al x to x=0–4.75 in Er 2Fe 17− x Al x ), while that in the rhombohedral structure decreases (from x=7.70–9.41 in Tb 2Fe 17− x Al x to x=5.70–7.03 in Er 2Fe 17− x Al x ). The cell parameters suggest that the nature of the atomic substitutions in the various crystal structures changes as a function of both structure type and atomic size of R.

Aluminum content of tea leaves and factors affecting the uptake of aluminum from soil into tea leaves

Numerous studies indicated that aluminum, the most abundant metallic element within the lithosphere, was considered to be related to some human diseases especially the Alzheimer’s disease. Tea, economically an important beverage in the world, has been found to contain higher concentration of aluminum than many other drinks and foods. Therefore, tea would be a potentially important source of dietary aluminum. In order to understand the sources of aluminum in tea leaves and factors related with aluminum content of tea leaves, an experiment was designed to investigate the relationships of aluminum in tea leaves with leaf age, soil properties and forms of aluminum in soils. The results showed that there were great distinctions in the concentration of aluminum in tea leaves with different leaf age (Alold leaf> Almature leaf> Alyoung leaf). Moreover, soil pH was the major factor controlling the uptake of aluminum from soil into tea leaves. Furthermore, the content of aluminum in tea leaves was better predicated by the soluble aluminum extracted by 0.02mol/L CaCl2.

Calculation of thermodynamic properties of LiFAlF 3, NaFAlF 3 and KFAlF 3

The scheme of dissociation of cryolite in NaFAlF 3 melts is proposed and applied to the LiFAlF 3 and KFAlF 3 systems. The constants and enthalpies of dissociation for alkali-cryolites are evaluated from experimental data. The mole fractions of each proposed species at 1298K in these three melt systems are calculated, and the variation of alumina solubility in alkali-cryolite can be explained on the basis of the ionic structure for the MF- AlF 3 ( M: Li, Na and K) melts. The thermodynamic properties and liquidus data of MF-AlF 3 systems are calculated by using the selected evaluated parameters. Some results are compared with experimental values.

Calculated Solubility of Trivalent Iron and Aluminum in Oxalic Acid Solutions At 25 °C.

Based on the principle of thermodynamic equilibrium, the solubility curves of trivalent iron and aluminum at 25 °C are presented and used as a guide for the prediction and understanding of the chemistry of these metal ions in oxalic acid solutions. The present paper proposes a framework derived from equilibrium thermodynamic data that was formulated to qualitatively correlate and predict the trivalent iron and aluminum species distribution in the Fe3+ − Al3+ − H2C2O4 − H2O system for oxalic acid concentrations varying between 1 and 10−6 M. The paper also advocates the use of graphical representations to visualise the importance of different appearing species in the system under study as a function of pH and oxalic acid concentration.La solubilité au 25 °C d' ions ferriques et aluminium dans de solutions d'acide oxalique a été calculée et représentée graphiquement, pour mieux comprendre et prédire la chimie de ces deux ions métalliques dans le millieu oxalique. Cet article propose un cadre, derivé des données d' équilibre thérmodynamique, pour correler et prédire la distribution des espèces ferriques et aluminium au système Fe3+ -Al3+ - H2C2O4 - H2O, pour des concentrations d' acide oxalique entre 1 et 10-6 M. Les avantages des représentations graphiques pour visualiser l'apparition de differentes espèces et leur importance rélative en fonction du pH et de la concentration d' ions oxalates sont aussi discutés dans cet article.

Calculated Solubility of Trivalent Iron and Aluminum in Oxalic Acid Solutions At 25 °C.

Based on the principle of thermodynamic equilibrium, the solubility curves of trivalent iron and aluminum at 25 °C are presented and used as a guide for the prediction and understanding of the chemistry of these metal ions in oxalic acid solutions. The present paper proposes a framework derived from equilibrium thermodynamic data that was formulated to qualitatively correlate and predict the trivalent iron and aluminum species distribution in the Fe3+ − Al3+ − H2C2O4 − H2O system for oxalic acid concentrations varying between 1 and 10−6 M. The paper also advocates the use of graphical representations to visualise the importance of different appearing species in the system under study as a function of pH and oxalic acid concentration.La solubilité au 25 °C d' ions ferriques et aluminium dans de solutions d'acide oxalique a été calculée et représentée graphiquement, pour mieux comprendre et prédire la chimie de ces deux ions métalliques dans le millieu oxalique. Cet article propose un cadre, derivé des données d' équilibre thérmodynamique, pour correler et prédire la distribution des espèces ferriques et aluminium au système Fe3+ -Al3+ - H2C2O4 - H2O, pour des concentrations d' acide oxalique entre 1 et 10-6 M. Les avantages des représentations graphiques pour visualiser l'apparition de differentes espèces et leur importance rélative en fonction du pH et de la concentration d' ions oxalates sont aussi discutés dans cet article.

Aluminum in lake water and organs of a fish Tribolodon hakonensis in strongly acidic lakes with a high aluminum concentration

Aluminum in lake water and in the organs of the fish Tribolodon hakonensis was investigated in Lake Usoriko (pH 3.6), Lake Inawashiroko (pH 5.0), and the Tenryu River (pH 7.7). The concentration of total soluble aluminum in the water was 0.51 mg l−1 in Usoriko, 0.05 mg l−1 in Inawashiroko, and less than 0.01 mg l−1 in the Tenryu. The chemical forms of soluble aluminum in the acid water were characterized as Al3+, AlL2+, and AlL≦1+. More than 90% of soluble aluminum in the water of Usoriko was Al3+, whereas AlL2+ was dominant in the water of Inawashiroko. The aluminum concentration in the organs of T. hakonensis in Usoriko was 42 μg g−1 wet weight in gills, 4.2 μg g−1 in muscle, 6.9 μg g−1 in bone, 12.7 μg g−1 in liver, 6.0 μg g−1 in kidney, and 6.0 μg g−1 in intestine, indicating accumulation of aluminum in the gills. The aluminum concentration in the organs of T. hakonensis living in Inawashiroko was approximately the same, in spite of the difference in water chemistry of the two acid lakes, especially for pH and aluminum. This suggests that aluminum accumulation might be controlled in the fish living in the acid lakes. In contrast, the aluminum concentration in the gills of T. hakonensis from the Tenryu was 2 μg g−1.

Short-term natural weathering of MSWI bottom ash

The release of heavy metals from MSWI bottom ash has been the key concern in the management of this material. The leaching distribution values obtained from 100 freshly quenched bottom ash samples, according to the German DIN 38414-S4 procedure test, showed the release of lead, zinc and copper to be the main hazards associated with bottom ash utilisation as a secondary building material. Currently, natural weathering of MSWI bottom ash, for an estimated period of 1–3 months, is the most economic treatment available to ensure the eventual utilisation of this material. The leaching of natural weathered bottom ash in the short-term (up to 9 months) was studied. The most significant changes in the bottom ash were found to occur in the first 90 days. At pH values greater than 12, lead, zinc and copper were the main heavy metals to be released from the MSWI freshly quenched bottom ash samples studied. Natural weathering for a period of about 90 days reduced the leaching of heavy metals, stabilising the bottom ash pH to minimise the solubility of metal hydroxides, and enabled the residue to be used as secondary building material. The profile of the pH neutralisation curve is similar to that described by carbonates, which would suggest that the reaction is controlled by CO 2. The formation of insoluble oxides as well as carbonates control the immobilisation of certain heavy metals, e.g. lead and zinc. The leaching of aluminium increases during this short natural weathering stage due to elemental metal oxidation. Aluminium solubility is controlled by the precipitation of gibbsite or other aluminium-sulphate neoformations. The latter may contribute to the immobilisation of heavy metals.

Investigation of Aluminum‐Indium Alloys for Interconnect Applications

This investigation was undertaken to evaluate indium (In) as an alloying element in Al for interconnects with improved reliability and performance compared to the currently used Al‐Cu alloys. The eventual goal is to prepare an aluminum‐indium‐lanthanum ternary alloy that would contain zero‐flux planes to limit the diffusion of aluminum within the alloy. However, research on Al‐In and Al‐La is required prior to tailoring the desired ternary alloys. Indium was chosen because it has negligible solid solubility in aluminum and possesses a valence shell electronic configuration identical to that of aluminum. Lower solubility in the bulk may lead to segregation of solute along the grain boundaries and hence, to improved electromigration resistance. Isovalency minimizes the adverse effect on the resistivity from solute addition to aluminum. The main characteristics of the alloy films that have been examined are variations of resistivity with solute content, redistribution of solute atoms, microstructural evolution, ease of dry etching, and adhesion to silicon dioxide . It is inferred from the results that even though aluminum‐indium (Al‐In) alloys exhibit low resistivity, they may not be suitable for interconnect applications due to poor adhesion of the as‐deposited films to , the tendency to form hillocks upon annealing, and nonuniform solute segregation. © 2000 The Electrochemical Society. All rights reserved.

Speciation of aluminum equilibria with kaolinite in acidic natural water

A computer model based on thermodynamic principles was used to investigate the speciation of aluminum in acidic natural water equilibria with mineral phase kaolinite. Compared to the case of equilibria with gibbsite, it was found that dissolved silica, fluoride ion and organic ligands influenced the aluminum speciation remarkably, while the concentrations of polymeric aluminum‐hydroxo species were insignificant. The equilibrium of soluble aluminum with kaolinite was two orders lower in magnitude than the equilibrium with gibbsite. This study indicated the potential harmfulness of toxic aluminum species formed in the acidified surface water to aquatic life.

The effects of acid sulphate run-off on a subtidal estuarine macrobenthic community in the Richmond River, NSW, Australia

The Richmond River is periodically exposed to acid sulphate run-off (ASR). Leaching of acidified water into this system commonly arises from infiltration of rainwater through acid sulphate soils that have been oxidized during construction of flood mitigation drains. Leaching events have been linked to major fish kills and can also lead to sublethal effects in fish, such as red spot disease. The effects of ASR on subtidal estuarine macrobenthic assemblages in the region of the Richmond known as the Tuckean Broadwater are examined here. Canonical correspondence analysis revealed that water transparency, pH, and soluble aluminium concentration were the most significant contributors to variation in macrobenthic community structure. Partial canonical correspondence analysis was performed to examine the effects of factors associated with ASR on the relative abundance of macrobenthic species, in isolation from the influence of other environmental variables. Variation in relative abundance was not significantly related to the individual effects of either soluble aluminium or pH. However, their combined effect on species abundance was significant, reflecting that macrobenthos at this site responded to chemical speciation of aluminium at certain pH ranges, rather than directly to either pH or soluble aluminium concentration. Results also showed that two species of sub-surface deposit-feeding polychaetes, Nephtys australiensis and Notomastus torquatus, were the most sensitive to the chemical speciation of aluminium and have tolerances for aluminium species that occur at different levels of acidification. The feeding activities of these two species may have removed the iron floc formed on the sediment surface under acidified conditions, thereby providing suitable conditions for other macrobenthic species to recolonize the Tuckean Broadwater.

Influence of nitrogen on hot ductility of steels and its relationship to problem of transverse cracking

The present review examines the influence of nitrogen on the hot ductility of steels, with particular relevance to the problem of transverse cracking during continuous casting. Nitrogen itself is not detrimental to hot ductility, but when it is present with aluminium or microalloying additions, ductility can be adversely affected through the formation of nitrides or carbonitrides. The addition of aluminium to low nitrogen C–Mn steels (0·005%N)impairs ductility during casting at an acid soluble level as low as 0·02%Al. This arises because segregation of aluminium to the grain boundaries occurs on solidification, and the temperature cycling that takes place when the strand is cooled encourages AlN precipitation. However, for low nitrogen, high strength low alloy (HSLA) steels with carbon levels in the peritectic range 0·08–0·17%C, transverse cracking is not generally encountered until the aluminium level is >0·04%. Higher nitrogen levels are likely to cause problems even at very low aluminium levels, as precipitation of AlN is controlled by the product of the aluminium and nitrogen contents. The microalloying additions vanadium and niobium are detrimental to ductility but, of the two elements, niobium is more damaging, as it gives finer precipitation. Increasing the nitrogen level has a more pronounced influence on ductility in vanadium containing steels, since vanadium forms a nitride while niobium forms Nb (CN), which is mainly carbon based. Nevertheless, the product of vanadium and nitrogen contents has to approach 1·2 × 10-3, for example 0·1%V and 0·012%N, before ductility deteriorates to that normally given by a niobium containing steel with 0·03%Nb and 0·005%N. When small titanium additions are made to low nitrogen C–Mn–Al steels (0·005%N), the best ductility is likely to be given by a high Ti/N ratio of 4–5 : 1; the excess titanium in solution encourages growth of the TiN particles. For high nitrogen steels (0·01%N), a low titanium level (0·01%)is recommended to limit the volume fraction of TiN particles. A low soluble aluminium level is also needed to prevent the excess nitrogen from combining to form AlN. For C–Mn–Nb–Al steels, similar recommendations can be made with regard to adding titanium. However, the presence of niobium and aluminium appears to have little influence on ductility, since these elements coarsen the titanium containing precipitates.

Matrix-isolated Al2OF6(2-) ion in molten and solid LiF/NaF/KF.

A Raman spectrum consistent with that expected from an Al2OF6(2-) ion was observed when Na2O was dissolved in a eutectic LiF/NaF/KF (FLINAK) melt at 500 degrees C, which contained a low concentration of either AlF3 or Na3AlF6. Furthermore, it was possible to trap the Al2OF6(2-) ion in the frozen solid and to measure its Raman and IR spectra at 25 degrees C. A number of bands have been detected; among those, the two most characteristic bands of the Al2OF6(2-) ion at 494 (polarized) and 265 cm-1 in the FLINAK melt at 500 degrees C, and those at 509 and 268 (Raman) and approximately 780 to approximately 900 (IR) cm-1 for the compound matrix isolated in solid FLINAK at 25 degrees C. In the absence of added oxide, the dissolved aluminum fluoride was in the form of the octahedral AlF6(3-) ion, which has characteristic Raman bands at 542 and 325 cm-1 in the FLINAK melt at 500 degrees C. Whereas alumina, Al2O3, was found to be essentially insoluble in FLINAK melts, it was possible to dissolve sufficient amounts of Na2O to convert most of the AlF6(3-) to the oxyfluoroaluminate, Al2OF6(2-). These solutions appeared to be metastable with respect to formation of insoluble alumina at higher temperatures. The present results can be compared to previous measurements on alumina dissolved in pure molten cryolite at much higher temperatures, where alumina solubility is low and broad bands due to oxide species are difficult to detect due to overlap with bands from AlF6(3-) and AlF4-.

Sulphuric acid pressure leaching of laterites — speciation and prediction of metal solubilities “at temperature”

Sulphuric acid pressure leaching of nickeliferous laterites has attracted considerable attention from the nickel industry during the past 5 years. The process is especially advantageous for limonitic laterites that mostly contain goethite, because iron precipitates releasing acid and thus rendering low acid consumption. It is also applicable to mixtures of limonites and saprolites, although at a higher acid consumption due to magnesium. Effective process design requires the solubility of metals that precipitate during the process to be known. In the present work, determination of metal solubilities is based on a simple speciation program that assumes the presence of only one dominant complex for each metal. The thermodynamic data for the precipitation reactions are extracted from high-temperature experiments with monometallic systems published previously. The validity of the approach is then tested against mixed bimetallic systems, and finally applied to calculate the solubility of aluminium, iron and magnesium in laterite leaching effluents “at temperature”. In both cases of limonitic feed and limonitic/saprolitic blends, the prediction closely follows metal solubilities measured experimentally at temperatures from 230 to 270°C and at terminal-free acidities ranging from 10 to 75 g/l.

Behavior of soil boron and boron uptake by M.26 apple rootstock as affected by application of different forms and nitrogen rates

The changes in availability and uptake of boron (B) by M.26 apple rootstocks as affected by applications of different forms and rates of nitrogen (N) were examined. The study was carried out in a greenhouse using soil with low contents of organic matter, clay, calcium carbonate, NH4‐oxalate soluble aluminum (Al) and iron (Fe), NH2OH·HCl extractable manganese (Mn), poor cation exchange capacity and low pH. Soil N application was in the form of urea, calcium nitrate, ammonium sulphate, or ammonium nitrate at rates of 0, 17, 34, and 51 mg N kg−1. After 1, 3, and 5 days of N application, soil B fractions were determined: B in soil solution, B specifically and non‐specifically adsorbed on soil surfaces, B occluded in Mn oxyhydroxides, and B occluded in crystalline Al and Fe oxides. The results showed that N as calcium nitrate and ammonium nitrate increased B both in soil solution and non‐specifically adsorbed on soil surface and decreased B concentration on Al and Fe oxides. This indicates that N‐NO3 inhibited B sorption on Fe and Al oxides. Maximum B desorption from Fe and Al oxides was obtained within one day after N‐NO3 was supplied. Nitrogen application as calcium nitrate and ammonium nitrate increased availability and uptake of B by plant roots. Thus, it was concluded that apple trees planted on coarse‐textured soils where risk of B deficiency is high, calcium nitrate or ammonium nitrates would be appropriately to apply to keep B more available.

Aluminium precipitates in the primary silicon of as-sprayformed hypereutectic aluminium-silicon alloys

Precipitates have been observed in the primary silicon of as-spray-formed hypereutectic aluminium-silicon alloys with and without various alloy additions. The precipitates have been investigated using transmission electron microscopy and high-resolution transmission electron microscopy. They are aluminium based and generally adopt a spheroidal morphology, with diameters in the range of approximately 5-10nm, unless located on a stacking fault or grain boundary. Spray forming is a rapid solidification process and precipitation occurs because of the low solid solubility of aluminium in silicon (maximum of 0.016 +/- 0.003at.% at 1190 C). The morphology of the precipitates suggests that they form from aluminium or aluminium-rich liquid. The orientation relationships of several precipitates in one of the primary silicon grains have been determined.

Bioaccumulation and toxicity of aluminium in the pond snail at neutral pH

The low solubility of aluminium (Al) at neutral pH means that it largely exists as colloidal particulates in aquatic systems. However, the pond snail Lymnaea stagnalis accumulates significant amounts of Al following exposure to water containing added Al (up to 500 microg l(-1)) at pH 7. This is accompanied by depression of behavioural activity (locomotion, feeding) which subsequently recovers, suggesting tolerance to the metal. The presence of silica ameliorates behavioural toxicity of Al, but does not prevent uptake of the metal. In vitro studies using the isolated central nervous system demonstrate toxicity at the cellular level. Extracellular application of Al (100 microM) led to membrane depolarisation, bursts of action potentials and action potential broadening. The chemical form in which Al is applied influences the extent of bioaccumulation and toxicity. Detailed knowledge of its solution chemistry is therefore essential.

Hydrogen Solubility, Diffusion and Trapping in High Purity Aluminum and Selected Al-Base Alloys

A review of experimental measurements of hydrogen solubility, diffusivity, and trapping in polycrystalline aluminum and selected Al-base precipitation age hardened materials is presented. There is widespread variability in experimentally measured effective diffusion coefficients and apparent solubilities in high purity aluminum and Al-alloys due to the sensitivity of test methods to surface oxides and hydrogen trapping at microstructural defects. Therefore, few measurements yield perfect lattice diffusivities and solubilities. This paper provides a compilation of available literature and presents some new data. Specifically, hydrogen interactions in high purity Al, Al-Li and Al-Cu binary alloys, Al-Li-Cu-Zr (AA 2090), Al-Cu-Mg (AA 2024), Al-Zn-Mg-Cu (AA 7075), and Al-Zn-Mg-Cu-Zr (AA 7050 and a low copper variant of AA 7050) alloys are reported. Several hydrogen trapping states are identified including dislocations, the distorted zone around vacancies, Li in solid solution, and specific precipitate phases.