Advanced manufacturing process of ultrahigh-purity α-Al2O3

Ambaryan, Grayr N.; Vlaskin, Mikhail S.; Buryakovskaya, Olesya A.; Kislenko, Sergey A.; Жук, А. З.; Школьников, Е. И.; Arnautov, Alexey N.; Zmanovsky, Sergey V.; Osipenkova, Alexandra A.; Тарасов, В. П.; Gromov, Alexander A.

doi:10.1016/j.susmat.2018.e00065

Cited by 8 publications

(4 citation statements)

References 28 publications

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“…[1] The alumina crystalline phase include a variety of substable phases and thermodynamically stable α-Al 2 O 3 or corundum. [2] At present, the common methods for preparing high-purity alumina powders are mainly the modified Bayer method, the thermal decomposition of aluminium hydroxide, the precipitation method and the hydrolysis of active high-purity aluminium, etc. All of these preparation methods are used to obtain the α-Al 2 O 3 phase by the decomposition of aluminium hydroxide.…”

Section: Introductionmentioning

confidence: 99%

EFFECT OF NH₄Cl ADDITIVES ON THE PHASE TRANSFORMATION AND MORPHOLOGY OF α-Al₂O₃

Guo¹

2023

Ceramics - Silikaty

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To investigate the effects of NH 4 Cl doping and the calcination temperature on the phase transformation and microscopic morphology of Al 2 O 3 , Al 2 O 3 powders were obtained by introducing different mass fractions of NH 4 Cl into the Al(OH) 3 powders and were then calcined at different temperatures. X-ray diffractometry and scanning electron microscopy were used for the phase analysis and particle morphology observation, respectively. The results showed that the addition of NH 4 Cl could reduce the phase transition temperature of α-Al 2 O 3 . With an increase in the NH 4 Cl addition, the α-Al 2 O 3 phase transition temperature significantly decreased. The transition phase was completely converted to α-Al 2 O 3 at 1100 °C with the addition of NH 4 Cl at 20 % at 1100 °C, which reduced both the phase transition temperature and the complete phase transition temperature of α-Al 2 O 3 by 100 °C. Meanwhile, the introduction of NH 4 Cl had no effect on the microscopic morphology of α-Al 2 O 3 . The α-Al 2 O 3 phases were worm-like with or without NH 4 Cl, and the doping of NH 4 Cl did not lead to the transitional growth of the complete phase-changed α-Al 2 O 3 grains.

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Section: Introductionmentioning

confidence: 99%

EFFECT OF NH₄Cl ADDITIVES ON THE PHASE TRANSFORMATION AND MORPHOLOGY OF α-Al₂O₃

Guo¹

2023

Ceramics - Silikaty

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“…With the progress in and development of science and technology, there have been a series of preparation methods for HPA materials, including organic aluminum alcohol hydrolysis, ammonium aluminum sulfate pyrolysis, ammonium aluminum carbonate pyrolysis, the modified Bayer method and the roasting method, etc. [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of High-Purity Mesoporous Alumina with Excellent Adsorption Capacity for Congo Red

Wang

et al. 2022

Materials

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We explore a more concise process for the preparation of high-purity alumina and to address the problem of some conventional micro- and nano-adsorbents having difficulty in exposing their adsorption sites to target pollutants in solution due to the heavy aggregation of the adsorbent, which confers poor adsorption properties. The methods of using gamma-phase high-purity mesoporous alumina (HPMA), with its excellent adsorption properties and high adsorption rates of Congo Red, and of using lower-cost industrial aluminum hydroxide by direct aging and ammonium salt substitution were successfully employed. The results showed that the purity of HPMA was as high as 99.9661% and the total removal rate of impurities was 98.87%, a consequence of achieving a large specific surface area of 312.43 m2 g−1, a pore volume of 0.55 cm3 g−1, and an average pore diameter of 3.8 nm. The adsorption process was carried out at 25 °C, the concentration of Congo Red (CR) dye was fixed at 250 mg L−1 and the amount of adsorbent used was 100 mg. The HPMA sample exhibited an extremely fast adsorption rate in the first 10 min, with adsorption amounts up to 476.34 mg g−1 and adsorption efficiencies of 96.27%. The adsorption equilibrium was reached in about 60 min, at which time the adsorbed amount was 492.19 mg g−1 and the dye removal rate was as high as 98.44%. One-hundred milligrams of adsorbent were weighed and dispersed in 200-mL CR solutions with mass concentrations ranging from 50–1750 mg L−1 to study the adsorption isotherms. This revealed that the saturation adsorption capacity of the produced HPMA was 1984.64 mg g−1. Furthermore, the process of adsorbing Congo Red in the synthesized product was consistent with a pseudo-second order model and the Langmiur model. It is expected that this method of producing HPMA will provide a productive, easy and efficient means of treating toxic dyes in industrial wastewater.

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“…Among these phases, the α-alumina is the most important due to its thermal and chemical stability [1]. α-alumina can be prepared by several methods from aluminum precursors such as aluminum metal, aluminum oxide or hydroxide, and its salts [2]. In order to prepare high pure alumina (HPA) the aluminum sources must be also pure.…”

Section: Introductionmentioning

confidence: 99%

PURIFICATION OF TAN RAI ALUMINUM HYDROXIDE WITH ACETIC ACID AND PREPARATION OF HIGH PURE NANOSIZE Α-Alumina

2022

Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.

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Gibbsite is the most common form of aluminum hydroxide (AH) as commercial product of Bayer process. However, it usually contains some impurities such as sodium, iron, calcium, and silicon compounds that may not meet requirements for preparation of advanced materials or functional ones which need very high pure raw materials. In this paper, we present some results on the purification of commercial AH from Tan-rai alumina company (Vietnam) using dilute acetic acid solution. The removal yields of 93.19, 91.75, 100, and 86.03% are obtained for Na2O, CaO, Fe2O3, and SiO2 respectively, whereas the recovery of clean AH is almost quantitative. The clean AH is then used for preparation of high pure nanosize α-alumina via chemical processes of dissolution, precipitation ammonium aluminium carbonate hydroxide (AACH) with ammonium carbonate solution. After washing the excess reagents, the precipitate of AACH is then decomposed at elevated temperature to get high pure nanosize α-alumina. The obtained product rather regular and most of particles are not agglomerated. The laser scattering data on the prepared sample show that the particle sizes of the prepared α-alumina from 60 – 90 nm are obtained which are in good agreement with the data from XRD and morphology measurements. The α-alumina structure of the final product is confirmed by the XRD measurement data.

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Advanced manufacturing process of ultrahigh-purity α-Al2O3

Cited by 8 publications

References 28 publications

EFFECT OF NH₄Cl ADDITIVES ON THE PHASE TRANSFORMATION AND MORPHOLOGY OF α-Al₂O₃

EFFECT OF NH₄Cl ADDITIVES ON THE PHASE TRANSFORMATION AND MORPHOLOGY OF α-Al₂O₃

Synthesis and Characterization of High-Purity Mesoporous Alumina with Excellent Adsorption Capacity for Congo Red

PURIFICATION OF TAN RAI ALUMINUM HYDROXIDE WITH ACETIC ACID AND PREPARATION OF HIGH PURE NANOSIZE Α-Alumina

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