Ratio of rate constants of milled boehmite (k*) and that of unmilled boehmite (k), with milling time is presented in Fig. 14. Larger the value of k*/k (of course greater than 1) greater was the effect. As seen in the figure, at larger milling time, the effectiveness of mechanical activation got reduced at higher temperature.
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Low-grade diasporic bauxite in central Guizhou Province, China, contains Li that can be exploited and utilized. In this paper, several methods were used to determine the main chemical components in low-grade diasporic bauxite, which were Al2O3, SiO2 and TiO2, and the main minerals were diaspore, boehmite, kaolinite, illite and anatase. …
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sis of the pure boehmite nanopowder with ink-bottle shaped pores at room temperature. In this work we report on the possibility to ob-∗Corresponding author: tel: +381 21 485 3758, e-mail: [email protected] tain crystalline boehmite at relatively low temperature (70°C) under ambient conditions where the formation of gibbsite or bayerite is avoided.
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The spectrum of bayerite resembles that of gibbsite whereas the spectrum of boehmite is similar to that of diaspore. Bayerite has four characteristic NIR bands at 7218, 7128, 6996, and 6895 cm −1. Gibbsite shows five major bands at 7151, 7052, 6958, 6898, and 6845 cm −1. Boehmite displays three NIR bands at 7152, 7065, and 6960 cm −1.
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Abstract The transformation of gibbsite into boehmite upon hydrothermal treatment at 200°C in 1.5 wt % NaOH have been studied by X-ray powder diffraction, IR spectroscopy, Brunauer–Emmett–Teller, differential scanning calorimetry, and scanning electron microscopy. The stages of the process have been determined. The …
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The co-occurence of boehmite and goethite indicates extreme in situ weathering. The minerals were recognized by their characteristic d-spacing (Å) and Position (°2 Th). The peak values were investigated and compared with the Joint Committee on Powder Diffraction Standards (JCPDS) information book and other published literature [ …
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3.1 Influence of Hydrothermal Treating Temperature on Phase and Morphology Evolution Characteristics of Boehmite Particles. Figure 1 shows the typical XRD patterns of as-obtained aluminum oxyhydroxide powder before/after hydrothermal treating at different temperatures for 10 h. As confirmed in pattern a, appearances of …
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Boehmite precipitation curve at 90 °C from a supersaturated sodium aluminate solution (132 g/L Al 2 O 3, 120 g/L Na 2 O, 500 min -1 and an initial seed concentration 230 g/L)
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Boehmite, white and relatively soft basic aluminum oxide [AlO (OH)] that is a common mineral in bauxite, in which it forms disseminated grains or pealike masses. It is …
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The boehmite solubility curve at higher ratios and at high temperatures (> 270 °C) begins to plateau and becomes more uncertain mainly because the boehmite cannot equilibrate fast enough with the liquor phase. Longer holding times may promote a higher rate of boehmite growth, and remove increased alumina concentrations from the liquor.
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Boehmite particles absorb protons on the surface hydroxyl groups and repel each other to form colloidal particles when the acid/aluminia ratio is low. With more hydrochloric acid …
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Bauxite, an aluminium ore, is the main source of aluminium metal. Bauxite contains a mixture of minerals, including gibbsite, boehmite, and diaspore, as well as iron oxides and kaolinite. The exact mineral composition of bauxite can vary depending on the location and geological processes that formed it. However, the primary mineral in bauxite ...
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The low-temperature nitrogen adsorption–desorption isotherms on intact boehmite and modified boehmite feature a characteristic hysteresis loop in the partial pressure range p/p 0 > 0.4, indicating a mesoporous structure of the supports ().The prepared boehmite has a high specific surface area, which varies in the range S sp = …
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However, J. Lapparent and J. De. Les have indicated that boehmite is formed at the ground-water level [16]. The same conclusion was made by V. A. Bronevoy and co-authors [17]. W. D. Keller believe that boehmite is formed when gels age in the presence of humic acids [18]. Researchers have argued that boehmite forms under acidic conditions [19–21].
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Conclusion. In this study, a method of synthesizing nano pseudoboehmite by neutralization in NH 4 Al (SO 4) 2 ·12H 2 O and NH 3 (aq) is reported. Using NH 4 Al (SO 4) 2 ·12H 2 O solution to extract alumina from fly ash, pseudoboehmite with flower-like structures were prepared, and the optimal crystal growth orientation was the (200) plane.
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Two kinds of boehmite to -alumina transformation mechanisms, namely collapse and reaction mechanisms, were elucidated crystallographically in detail with new insights …
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γ-Alumina is a widely used material, while its precise crystal structure and transformation mechanism derived from boehmite have remained unclear in the literature for decades. In this work, quantitative electron microscopy has been applied to study the crystalline structure of γ-alumina and its transformation mechanism from …
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In this study, hierarchical boehmite (γ-AlOOH) hollow microspheres with highly active surface were prepared by hydrothermal synthesis. Scanning electron …
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The pore size and type of aluminum oxy-hydroxide (boehmite) obtained using an optimized sol–gel method was investigated as a mesoporous material with the calcination temperature varied from 150 to 550 °C. Structural features were characterized by XRD, SEM, TEM, BET. Molecular interactions were identified by using PALS (positron …
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Boehmite is a high-temperature resistant aluminum oxide-hydroxide. The functional filler is used as a carrier material for catalytic converters or as a flame retardant in printed circuit boards. In the growing market of electromobility, boehmite is also finding increasing use. the minerals boehmite (aluminum oxyhydroxide, γ-AlOOH) and gibbsite ...
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Among the six crystalline phases of alumina, only boehmite is biocompatible and also will be used for further biological tests. After physical sol-gel condensation of …
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Steven L. Baxter. Article. Metrics. Get access. Cite. Abstract. Certain forms of monohydrate aluminum oxide, commonly known as boehmite or pseudoboehmite …
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Abstract A method is proposed for the synthesis of nanoscale boehmite powder at low temperatures of hydrothermal treatment in 1.5 wt % HCl solution at 150 and 170°C and in water at 80, 100, and 130°C. The optimal parameters of hydrothermal treatment are found. The conversion stages of γ-Al2O3 to boehmite (AlOOH) are found; …
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Boehmite has been studied for decades owing to its essential industrial importance. In particular, boehmite being a precursor of γ-alumina is widely found in alumina related industries: catalyst carriers, ceramics, metallurgy, treatment of Al-rich radioactive waste. Most boehmite properties are related to its particular structure.
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Boehmite [bey-mahyt] is a unique aluminum oxide hydroxide nanostructure. It consists of nanosheets of octahedral aluminum ions with surface hydroxyl groups. Owing to exceptional reinforcing behavior, boehmite nanoparticles have gained immense attention as polymeric nanofillers. Essential matrices used with the boehmite based nanocomposites ...
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We report on the synthesis of boehmite aluminum oxide hydroxide particles with lamellar structure (γ-AlO (OH)) obtained from the recycling of metallic can seals, …
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Fire Retardant Fillers for Polymers. R. Rothon, P. Hornsby, in Polymer Green Flame Retardants, 2014 7.2 Boehmite. Boehmite has the composition AlO(OH) and has already been mentioned as an intermediate in the decomposition of aluminum hydroxide and is being promoted commercially as a flame retardant. As demonstrated in Table 6 and …
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The relationship between microstructure changes and rheological properties in suspensions containing boehmite particles, which are well applied in various industrial wash-coating processes, was investigated by changing pH condition. The boehmite particles in suspensions were either well dispersed or aggregated depending on the pH, …
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Surface Models. The boehmite unit cell, with parameters a = 3.709 ˚A, b = 12.24 ˚A, c = 2.876 ˚A, and α= β= γ= 90, obtained from Christensen et al.20 was used to generate supercells to study the aqueous interface at the (010) basal surface and the (100), (001), and (101) edges of boehmite.
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The Crystal Structure of Synthetic Boehmite. Paul P. Reichertz; W. Jacque Yost. J. Chem. Phys. 14, 495–501 (1946) https://doi/10.1063/1.1724179. Article …
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4.1 FT-IR. The incorporation of boehmite nanoparticles into PVAc has been monitored using FT-IR spectroscopy, and the results are shown in Fig. 1.The FT-IR spectra of boehmite nanoparticles show a strong absorption band at 3400 cm −1 is due to the strong hydrogen bonds exist between the AlOOH layers and the water molecules that …
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The aluminum oxihydroxide boehmite (γ-AlOOH) is the topotactic precursor of γ-alumina, widely used as a support of refining catalysts. We use ab initio calculations and molecular dynamics (MD) to study water–boehmite interfacial properties, which are believed to play a key role during the industrial synthesis of boehmite in aqueous solution.
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Boehmite (Al2O3.H2O) | Al2H2O4 | CID 23295517 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological ...
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