Structure Transformation of Gibbsite by Calcination

Ogata, Fumihiko; Kawasaki, Naohito; Kabayama, Mineaki; Nakamura, Takeo; Tanada, Seiki

doi:10.1380/ejssnt.2006.267

Cited by 6 publications

(5 citation statements)

References 6 publications

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“…The increase in the surface area of treated samples is due to the decrease in particle size. These results are in good agreement with that of Ogata et al ., 19 who used gibbsite as the starting material and found that the specific surface area increased when the calcination temperature increased.…”

Section: Resultssupporting

confidence: 92%

“…Gibbsite (α‐Al(OH) 3 ) is a cheap starting material widely used in the transformation of alumina because it can be dehydrated to various phases (χ,γ,θ,κ,α) 18,19 Figure 1. shows the diagram of phase transformation of alumina from gibbsite.…”

Section: Introductionmentioning

confidence: 99%

“…Gibbsite (a-Al(OH) 3 ) is a cheap starting material widely used in the transformation of alumina because it can be dehydrated to various phases (w,g,y,k,a). 18,19 Figure 1 shows the diagram of phase transformation of alumina from gibbsite. The transformation route depended on temperature, heating environment, particle size of staring gibbsite, and heating rate.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Milling on the Formation of Nanocrystalline χ‐Al₂O₃ from Gibbsite

Chaitree

Jiemsirilers

Mekasuwandumrong

et al. 2010

Journal of the American Ceramic Society

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Gibbsite (FG) with mean particle diameter (d50=13 μm) was milled in an attrition mill for 12 and 24 h using alumina balls as grinding media and calcined at different temperatures in the range of 350°–600°C. The properties of the alumina obtained were determined by X‐ray diffraction, N2 physisorption, thermogravimetric/differential thermal analyses, and transmission electron microscopy. Without milling, the alumina obtained normally contained the mixed phases between γ‐ and χ‐phase alumina. On the other hand, high purity of nanocrystalline χ‐phase alumina (100 wt%) can be produced by calcination of the 24‐h milled FG at 600°C. The isothermal kinetics measurements revealed that the rate constant (k) for phase transformation increased as the particle size of gibbsite decreased and the calculated activation energy for transformation from FG to alumina decreased from 20.6 to 14.7 and 6.8 kJ/mol after milling for 12 and 24 h, respectively. The physical properties of nanocrystalline χ‐alumina obtained by the calcination of milled FG were comparable to those produced by the solvothermal method. The present results offer a simple way to prepare a large amount of pure χ‐phase alumina for particular industrial applications.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Milling on the Formation of Nanocrystalline χ‐Al₂O₃ from Gibbsite

Chaitree

Jiemsirilers

Mekasuwandumrong

et al. 2010

Journal of the American Ceramic Society

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“…Adsorbent (GB400) had a boehmite structure (AlOOH). Changes of properties of GB (pH, amount of hydroxyl group, specific surface area, and pore volume) by calcination may depend upon that (Ogata et al, 2006;Kawasaki et al, 2008;Ogata et al, 2009). Figure 2 shows the amount of cisplatin adsorbed onto GB400 at different pH values, where it can be seen that the optimal pH condition for the adsorption of cisplatin onto GB400 was 8.5.…”

Section: Results and Discussion Properties Of Gb And Gb400mentioning

confidence: 99%

Use of Calcined Gibbsite to Remove Cisplatin from Aqueous Solutions

Ogata

Inoue

Tominaga

et al. 2014

J. of Wat. ^|^ Envir. Tech.

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In the present study, GB400 was prepared by calcination of gibbsite (GB) at 400°C. The properties of GB and GB400 were investigated and the adsorption of cisplatin onto GB400 was evaluated. The scanning electron microscopy images were obtained and specific surface area, mean pore diameter, pore volume, number of hydroxyl groups, and the solution pH were measured. The observed values for GB400 were superior to those of GB. The optimal pH condition for adsorption of cisplatin using GB400 was about 8. Equilibrium adsorption of cisplatin onto GB400 was reached within 24 h. These experimental data were fitted to the pseudo-second-order equation. Moreover, the amount of cisplatin adsorbed onto GB400 was increased proportionally with temperature. The experimental data were fitted to the Langmuir equation model. The ΔG values were less than-80 kJ/mol, which indicate that the adsorption mechanism of cisplatin onto GB400 is related to chemisorption. The ΔH values were negative, indicating that the adsorption of cisplatin onto GB400 is exothermic. The positive values of ΔS signify an irregular increase of the randomness at the GB400/solution interface during the adsorption process. Cisplatin adsorbed onto GB400 was desorbed using hydrochloric acid solution.

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“…Meanwhile, it can be seen that with increase of calcination temperature from 5508C to 9508C, there was a significant decrease for S BET from 175.5 to 46.5 m 2 g 21 . It has been reported that decrease of specific surface area caused by of noncrystalline aluminium oxide is attributed to formation of thermodynamically stable structure(Goldberg et al 2001) Ogata & Kawasaki (2006). reported that specific surface area decreased when amorphous aluminium oxide became aluminium oxide with crystal structure by raising calcination temperature.…”

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confidence: 99%

Applicability of reused industrial dry sanding powder for adsorption of arsenic

Park

Yang

Choi

2008

Water Science and Technology

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This study examined the potential reuse of powdered wastes (PW) generated during the sanding and sawing process in a local chemical company in Korea with the viewpoint of the recycling these wastes and minimizing the level of contamination. As the aluminium hydroxide inside the PW could be thermally converted to various types of aluminium oxides depending on the calcination temperature, the adsorptive properties could be changed and it may affect on adsorption ability. Calcination of the PW was performed for 3 h at 550 degrees C, 750 degrees C, and 950 degrees C. From the results, amorphous aluminium oxide was thermally generated by calcinating the PW at 550 degrees C and with further increase of temperature to 950 degrees C, the crystallinity of amorphous aluminium oxide was gradually increased. The physicochemical analysis of calcined powdered wastes (CPW) at various temperatures showed that more developed porosity was noted in the CPW as the calcinations temperature increased, whereas surface area was significantly decreased from 175.5 m2 g(-1) to 46.5 m2 g(-1). The removal efficiency of arsenate on the CPW decreased as the calcinations temperature increased from 550 degrees C to 950 degrees C. The CPW550 exhibited the highest adsorption capacities toward arsenate over pH range of 2-8 and showed a complete removal of the arsenate (10.0 mg L(-1)) within the first 10 min. Adsorption kinetic studies showed that the rate of arsenic adsorption on the CPW decreased with the increase of the calcination temperature. When the maximum adsorption capacity of arsenic onto the CPW was calculated by Langmuir equation, the CPW550 has the highest value as 43.9 mg g(-1).

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Structure Transformation of Gibbsite by Calcination

Cited by 6 publications

References 6 publications

Effect of Milling on the Formation of Nanocrystalline χ‐Al₂O₃ from Gibbsite

Effect of Milling on the Formation of Nanocrystalline χ‐Al₂O₃ from Gibbsite

Use of Calcined Gibbsite to Remove Cisplatin from Aqueous Solutions

Applicability of reused industrial dry sanding powder for adsorption of arsenic

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Structure Transformation of Gibbsite by Calcination

Cited by 6 publications

References 6 publications

Effect of Milling on the Formation of Nanocrystalline χ‐Al2O3 from Gibbsite

Effect of Milling on the Formation of Nanocrystalline χ‐Al2O3 from Gibbsite

Use of Calcined Gibbsite to Remove Cisplatin from Aqueous Solutions

Applicability of reused industrial dry sanding powder for adsorption of arsenic

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Effect of Milling on the Formation of Nanocrystalline χ‐Al₂O₃ from Gibbsite

Effect of Milling on the Formation of Nanocrystalline χ‐Al₂O₃ from Gibbsite