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Bulletin of Environmental Contamination... Jul 2022
Topics: Aluminum Oxide; Soil
PubMed: 35789281
DOI: 10.1007/s00128-022-03578-4 -
Molecules (Basel, Switzerland) May 2019The MgAlO-spinel has wide applications in various industries and in geosciences. It shows a significant inter-site Mg-Al cation exchange (denoted by the inversion... (Review)
Review
The MgAlO-spinel has wide applications in various industries and in geosciences. It shows a significant inter-site Mg-Al cation exchange (denoted by the inversion parameter ), which modifies structural features, such as the unit-cell parameters and the sizes of the component polyhedra, and influences the physical and chemical properties. Previous studies mainly focused on the kinetics and thermodynamics of the Mg-Al exchange reaction, with the aim to ascertain the correlation between the inversion parameter and temperature; these studies, however, reached conflicting results. Here, we first reviewed the kinetics studies on the Mg-Al cation exchange reaction, and then reviewed all thermodynamic experiments, with special attention paid to the Mg-Al cation exchange equilibrium and the quench process, which might have modified the cation distributions once attained at high temperatures. We also assessed the accuracies in the temperature measurements and in the quantifications of the by different analytical methods. With some necessary temperature correction and data removal, we have landed with a generally reliable - dataset covering the - space of 873 < < 1887 K and 0.18(1) < < 0.357(60) (71 data pairs in total). Fitting these - data to three most commonly used thermodynamic models, we have obtained more accurate model parameters. Further, we also evaluated the constituent items of the Gibbs free energy for the Mg-Al cation exchange reaction with experimental results from different research fields and reached the conclusion that highly possibly the T Δ S D should not be neglected. Based on this review, we suggest that: (1) Further kinetics study on the Mg-Al exchange reaction should be performed at both low (<~973 K) and high (>~1173 K); (2) further Mg-Al exchange equilibrium studies should be carried out at relatively low and ambient , as well as in vast ranges of simultaneous high and high ; and (3) direct experimental measures about the entropies or the enthalpies of the MgAlO-spinels disordered to different extents should be conducted with full characterization of the starting materials and detailed description of the experimental procedures.
Topics: Aluminum Oxide; Entropy; Hydrogen-Ion Concentration; Kinetics; Magnesium Oxide; Molecular Structure; Thermodynamics
PubMed: 31052437
DOI: 10.3390/molecules24091704 -
Environmental Science and Pollution... Apr 2024In aluminum electrolysis, the iron-rich cover material is formed on the cover material and the steel rod connecting the carbon anode. Due to the high iron content in the...
In aluminum electrolysis, the iron-rich cover material is formed on the cover material and the steel rod connecting the carbon anode. Due to the high iron content in the iron-rich cover material, it differs from traditional cover material and thus requires harmless recycling and treatment. A process was proposed and used in this study to recovery F, Al, and Fe elements from the iron-rich cover material. This process involved aluminum sulfate solution leaching for fluorine recovery and alkali-acid synergistic leaching for α-AlO and FeO recovery were obtained. The optimal leaching rates for F, Na, Ca, Fe, and Si were 93.92, 96.25, 94.53, 4.48, and 28.87%, respectively. The leaching solution and leaching residue were obtained. The leaching solution was neutralized to obtain the aluminum hydroxide fluoride hydrate (AHFH, AlF(OH)·(HO)). AHFH was calcined to form a mixture of AlF and AlO with a purity of 96.14%. The overall recovery rate of F in the entire process was 92.36%. Additionally, the leaching residue was sequentially leached with alkali and acid to obtain the acid leach residue α-AlO. The pH of the acid-leached solution was adjusted to produce a black-brown precipitate, which was converted to FeO under a high-temperature calcination, and the recovery rate of Fe in the whole process was 94.54%. Therefore, this study provides a new method for recovering F, Al, and Fe in iron-rich cover material, enabling the utilization of aluminum hazardous waste sources.
Topics: Ferric Compounds; Electrolysis; Aluminum; Fluorides; Aluminum Oxide; Iron; Aluminum Compounds; Recycling
PubMed: 38512573
DOI: 10.1007/s11356-024-32877-y -
ACS Chemical Neuroscience Dec 2022Studies demonstrated that alumina nanoparticles (alumina NPs) impair spatial cognition and hippocampus-dependent synaptic plasticity. Although alumina NPs accumulate in...
Studies demonstrated that alumina nanoparticles (alumina NPs) impair spatial cognition and hippocampus-dependent synaptic plasticity. Although alumina NPs accumulate in the prefrontal cortex (PFC), their effects on PFC-mediated neuronal and cognitive function have been not yet documented. Here, alumina NPs (10 or 20 μg/kg of body weight) were bilaterally injected into the medial PFC (mPFC) of adult rats, and the levels of glycogen synthase kinase 3β (GSK3β) and the brain-derived neurotrophic factor (BDNF) were detected. The PFC-dependent working memory task with one-minute or three-minute delay time was conducted. Meanwhile, the neuronal correlates of working memory performance were recorded. The specific expression of neuronal BDNF was assessed by colabeled BDNF expression with the neuronal nuclear antigen (NeuN). Whole-cell patch-clamp recordings were employed to detect neuronal excitability. Intra-mPFC alumina NP infusions significantly enhanced the expression of GSK3β but reduced the phosphorylation of GSK3β (pGSK3β) and BDNF levels more severely at a dose of 20 μg/kg. Alumina NPs acted in a dose-dependent manner to impair working memory. The neuronal expression of BDNF in the 20 μg/kg group was markedly declined compared with the 10 μg/kg group. During the delay time, the neuronal frequency of pyramidal cells but not interneurons was significantly weakened. Furthermore, both the frequency and amplitude of the excitatory postsynaptic currents (EPSCs) were descended in the mPFC slices. Additionally, the infusion of GSK3β inhibitor SB216763 or BDNF could effectively attenuate the impairments in neuronal correlate, neuronal activity, and working memory. From the perspective of the identified GSK3β/BDNF pathway, these findings demonstrated for the first time that alumina NPs exposure can be a risk factor for prefrontal neuronal and cognitive functions.
Topics: Animals; Rats; Aluminum Oxide; Brain-Derived Neurotrophic Factor; Memory, Short-Term; Prefrontal Cortex; Signal Transduction
PubMed: 36444509
DOI: 10.1021/acschemneuro.2c00383 -
Biotechnology and Applied Biochemistry May 2016Aluminum oxide nanoparticles (Al2 O3 -NPs) are important ceramic materials that have been used in a variety of commercial and industrial applications. However, the...
Aluminum oxide nanoparticles (Al2 O3 -NPs) are important ceramic materials that have been used in a variety of commercial and industrial applications. However, the impact of acute and chronic exposure to Al2 O3 -NPs on the environment and on human health has not been well studied. In this investigation, we evaluated the cytotoxic effects of Al2 O3 -NPs on human mesenchymal stem cells (hMSCs) by using a cell viability assay and observing cellular morphological changes, analyzing cell cycle progression, and monitoring the expression of cell cycle response genes (PCNA, EGR1, E2F1, CCND1, CCNC, CCNG1, and CYCD3). The Al2 O3 -NPs reduced hMSC viability in a dose- and time-dependent manner. Nuclear condensation and fragmentation, chromosomal DNA fragmentation, and cytoplasmic vacuolization were observed in Al2 O3 -NP-exposed cells. The nuclear morphological changes indicated that Al2 O3 -NPs alter cell cycle progression and gene expression. The cell cycle distribution revealed that Al2 O3 -NPs cause cell cycle arrest in the sub-G0-G1 phase, and this is associated with a reduction in the cell population in the G2/M and G0/G1 phases. Moreover, Al2 O3 -NPs induced the upregulation of cell cycle response genes, including EGR1, E2F1, and CCND1. Our results suggested that exposure to Al2 O3 -NPs could cause acute cytotoxic effects in hMSCs through cell cycle regulatory genes.
Topics: Aluminum Oxide; Biological Transport; Biomarkers; Cell Cycle; Cell Survival; Cyclin D1; Early Growth Response Protein 1; Gene Expression Regulation; Humans; Mesenchymal Stem Cells; Nanoparticles
PubMed: 25779086
DOI: 10.1002/bab.1368 -
Waste Management (New York, N.Y.) Feb 2017Fly ash, a by-product of high temperature combustion of coal in coal-fired power plants, is one of the most complex and largest amount of industrial solid wastes... (Review)
Review
Fly ash, a by-product of high temperature combustion of coal in coal-fired power plants, is one of the most complex and largest amount of industrial solid wastes generated in China. Its improper disposal has become an environmental problem. Now it is widely realized that fly ash should be considered as a useful and potential mineral resource. Fly ash is rich in alumina, making it a potential substitute for bauxite. With the diminishing reserves of bauxite resources, as well as the increasing demand for alumina, recovery of alumina from fly ash has attracted extensive attention world-wide. The present review describes, firstly, the generation and physicochemical properties of high alumina fly ash found in northern China and then focuses on the various alumina recovery technologies, the advantages and disadvantages of these processes, and in particular, the latest industrial developments. Finally, the directions for future research are also considered.
Topics: Aluminum Oxide; Coal Ash; Industrial Development; Waste Management
PubMed: 27346594
DOI: 10.1016/j.wasman.2016.06.009 -
Archives of Toxicology Oct 2015Aluminum oxide nanoparticles are listed among 14 high-priority nanomaterials published by the Organization for Economic Co-operation and Development, but limited... (Comparative Study)
Comparative Study
Aluminum oxide nanoparticles are listed among 14 high-priority nanomaterials published by the Organization for Economic Co-operation and Development, but limited information is available on their potential hazards. In this study, we compared the toxicity of two different aluminum oxide nanorods (AlNRs) commercially available in vivo and in vitro. Considering aspect ratio, one was 6.2 ± 0.6 (long-AlNRs) and the other was 2.1 ± 0.4 (short-AlNRs). In mice, long-AlNRs induced longer and stronger inflammatory responses than short-AlNRs, and the degree reached the maximum on day 7 for both types and decreased with time. In addition, in vitro tests were performed on six cell lines derived from potential target organs for AlNPs, HEK-293 (kidney), HACAT (skin), Chang (liver), BEAS-2B (lung), T98G (brain), and H9C2 (heart), using MTT assay, ATP assay, LDH release, and xCELLigence system. Long-AlNRs generally produced stronger toxicity than short-AlNRs, and HEK-293 cells were the most sensitive for both AlNRs, followed by BEAS-2B cells, although results from 4 kinds of toxicity tests conflicted among the cell lines. Based on these results, we suggest that toxicity of AlNRs may be related to aspect ratio (and resultant surface area). Furthermore, novel in vitro toxicity testing methods are needed to resolve questionable results caused by the unique properties of nanoparticles.
Topics: Aluminum Oxide; Animals; Cell Line; Cell Line, Tumor; HEK293 Cells; Humans; Inflammation; Male; Mice; Mice, Inbred ICR; Nanotubes; Rats; Toxicity Tests
PubMed: 25155191
DOI: 10.1007/s00204-014-1332-5 -
Environmental Science and Pollution... Apr 2023It is important to remove active substances from secondary aluminum dross (SAD) to meet the reuse of SAD. In this work, the removal of active substances from different...
It is important to remove active substances from secondary aluminum dross (SAD) to meet the reuse of SAD. In this work, the removal of active substances from different particle sizes of SAD was studied using roasting improvement with particle sorting. The results showed that roasting after particle sorting pretreatment can effectively remove fluoride and aluminum nitride (AlN) from SAD, while getting the high-grade alumina (AlO) crude materials. The active substances of SAD mainly contribute to AlN, aluminum carbide (AlC), and soluble fluoride ions. AlN and AlC mainly exist in particles of 0.05-0.1 mm, while Al and fluoride are mainly in particles of 0.1-0.2 mm. The SAD of particle size ranging 0.1-0.2 mm has high activity and leaching toxicity; the gas emission was reached 50.9 mL/g (limit value of 4 mL/g), and the fluoride ion concentration in the literature was 137.62 mg/L (limit value of 100 mg/L) during the identification for reactivity and leaching toxicity according to GB5085.5-2007 and GB5085.3-2007, respectively. Roasting at 1000 °C for 90 min, the active substances of SAD were converted to AlO, N, and CO; meanwhile, soluble fluoride converted to stable CaF. The final gas release was reduced to 2.01 mL/g while soluble fluoride from SAD residues was reduced to 6.16 mg/L, respectively. The AlO content of SAD residues was determined at 91.8% and has been classified as category I solid waste. The results suggested that the roasting improvement with particle sorting of SAD can meet the reuse of valuable materials at full scale.
Topics: Aluminum; Fluorides; Aluminum Compounds; Aluminum Oxide
PubMed: 36872407
DOI: 10.1007/s11356-023-26201-3 -
The International Journal of... Oct 2023To investigate the effects of airborne-particle abrasion and nanosilica (nano-Si) infiltration treatment on the surface characteristics of dental zirconia.
PURPOSE
To investigate the effects of airborne-particle abrasion and nanosilica (nano-Si) infiltration treatment on the surface characteristics of dental zirconia.
MATERIALS AND METHODS
A total of 15 unsintered zirconia ceramic green bodies (10 × 10 × 3 mm) were divided into three groups (n = 5): Group C, no treatment after sintering; Group S, airborne-particle abrasion with 50-μm aluminum oxide particles after sintering; and Group N, infiltration of nano-Si followed by sintering and hydrofluoric acid (HF) etching. The zirconia disks' surface roughness was analyzed by atomic force microscopy (AFM). The surface morphology of the specimens was analyzed using scanning electron microscopy (SEM), and the chemical composition was analyzed by energy-dispersive x-ray (EDX). Data were statistically analyzed by the Kruskal-Wallis test (P < .05).
RESULTS
Zirconia surface treatments by infiltration of nano-Si, sintering, and HF etching showed multiple changes in the surface features. The surface roughness of Groups C, S, and N were 0.88 ± 0.07 μm, 1.26 ± 0.10 μm, and 1.69 ± 0.15 μm, respectively. The surface roughness of Group N was significantly higher than that of Groups C and S (P < .05). EDX analysis showed peaks that corresponded to silica (Si) after infiltration with colloidal Si that disappeared following acid etching.
CONCLUSIONS
Infiltrating nano-Si increases the surface roughness of zirconia. The formation of retentive nanopores on the surface potentially improves the zirconia-resin cement bonding strengths.
Topics: Humans; Dental Bonding; Surface Properties; Ceramics; Zirconium; Resin Cements; Aluminum Oxide; Materials Testing; Microscopy, Electron, Scanning; Dental Etching
PubMed: 37879051
DOI: 10.11607/prd.6318 -
Bulletin of Experimental Biology and... Feb 2022A comparative study of the effect of a sorbent with nanotubes (AlO@ WCNT-PDMS) and a carbon-mineral sorbent (AlO@C) on the parameters of human erythrocytes was carried...
A comparative study of the effect of a sorbent with nanotubes (AlO@ WCNT-PDMS) and a carbon-mineral sorbent (AlO@C) on the parameters of human erythrocytes was carried out. Using scanning flow cytometry, the morphological and functional parameters of venous blood erythrocytes as well as drainage blood after its perfusion through columns with sorbents were determined. The compared samples AlO@SWCNT-PDMS and AlO@C are similar by their effect on the morphological and functional parameters of erythrocytes. The maximum membrane extensibility increased to a greatest extent after contact with AlO@C, the amount of hemoglobin in erythrocytes decreased to the greatest extent after perfusion through a column with AlO@SWCNT-PDMS sorbent. The scanning flow cytometry is promising for assessing the effect on erythrocytes of new sorption materials intended for blood detoxification. Changes in the parameters of erythrocytes of blood collected in a sterile drainage system for subsequent reinfusion were revealed.
Topics: Aluminum Oxide; Dimethylpolysiloxanes; Erythrocytes; Humans; Minerals; Nanotubes, Carbon
PubMed: 35175474
DOI: 10.1007/s10517-022-05417-2