The Crystal Structure of Boehmite

Christoph, Gary G.; Corbató, Charles E.; Hofmann, Douglas A.; Tettenhorst, Rodney

doi:10.1346/ccmn.1979.0270201

Cited by 100 publications

(65 citation statements)

References 8 publications

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“…Cell dimensions determined from the diffraction data calibrated by ring diffraction of gold are approximately a = 4.5 and c = 2.7/~. The values are close to the cell dimensions of diaspore (a = 4.396 and c = 2.844/~; Brown 1980) rather than those ofboehmite (a = 3.6936 and c = 2.8679/~; Christoph et al 1979). It is also well known that aluminum hydroxides occurring in the order as increasing the temperature are as follows: gibbsire (3'-Al(OH)3) ~ boehmite (3,-AIOOH) ~ diaspore (a-AIOOH).…”

Section: Edx (supporting

confidence: 55%

Experimental Study on the Formation of Clay Minerals from Obsidian by Interaction with Acid Solution at 150° and 200°C

Kawano

Tomita

1995

Clays and clay miner.

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Abstract--Experimental alteration of obsidian with HC1 solution was performed to elucidate dissolution mechanism and formation process of clay minerals in acid solution. Reactions were carried out using 0.1, 0.5, and 4.0 g of obsidian to 100 ml of 0.01 N HCI solution at 150" and 200"C for 1 to 60 days. The reaction products were examined by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray analysis. The surface composition of obsidian before and after alteration was investigated by X-ray photoelectron spectroscopy (XPS). TEM showed that boehmite precipitated at early stage and spherical kaolinite appeared subsequently by 200*(2 reactions. However, spherical halloysite occurred predominantly with small amounts of allophane, boehmite, and kaolinite by 150*(3 reaction in which formation process of the halloysite from allophane passing through an intermediate phase of small size rounded aggregate that consists of fine particles of allophane was observed. A boehmite exhibiting hexagonal platy habit with higher degree of crystallinity was formed by 200"C reaction as a stable phase in solution containing lower Si concentration at which the solution composition coincides with the stability field of boehmite on activity diagram for the system Na~O-m1203-SiO2-H20. The fibrous boehmite having lower crystallinity appeared with increasing Si concentration, considered as a metastable phase in the stability field of kaolinite. XPS indicated that dissolution of obsidian in acid solution proceeded initially by cation exchange between Na ions and hydronium ions in solution and subsequently by preferential release of Al ions relative to Si from the Na depleted surface.

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Section: Edx (supporting

confidence: 55%

Experimental Study on the Formation of Clay Minerals from Obsidian by Interaction with Acid Solution at 150° and 200°C

Kawano

Tomita

1995

Clays and clay miner.

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“…pseudo-boehmite and lowcrystalline ␣-alumina (labeled as alumina-A). Boehmite has a layer structure similar to ␥-FeOOH, consisting of linked chains of AlO 6 octahedra, which run parallel to the c-axis, forming an infinite two-dimensional sheet [16]. Pseudo-boehmite is a kind of low-crystalline boehmite, distinguished by the broadened XRD diffraction peaks and large specific surface area [17].…”

Section: Characterization Of the Aluminum (Hydr)oxidesmentioning

confidence: 99%

Adsorption of phosphate at the aluminum (hydr)oxides–water interface: Role of the surface acid–base properties

Yang

Wang

Sun

et al. 2007

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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In this paper, the adsorption of phosphate on two crystallized aluminum oxides, pseudo-boehmite (pseudo-␥-AlOOH) and ␣-Al 2 O 3 , was studied. The adsorption experiments were carried out in 0.01 M KNO 3 solutions at pH 4 and 6, respectively. Adsorption densities were calculated to evaluate the phosphate adsorption affinity for the two aluminum oxides. To better understand the effect of surface properties on the adsorption behavior of phosphate, the surface structure and properties were investigated with X-ray diffraction, N 2 adsorption-desorption, electron microscope observation and surface acid-base titrations. The results from adsorption isotherms showed that at both pH 4 and 6, pseudo-␥-AlOOH exhibited greater adsorption capacity than ␣-Al 2 O 3 . For both pseudo-␥-AlOOH and ␣-Al 2 O 3 , the adsorbed amount of phosphate at pH 4 was higher than that at pH 6. Adsorption density calculation indicated that ␣-Al 2 O 3 had greater affinity for phosphate than pseudo-␥-AlOOH. Information gained from examinations of surface properties revealed that the specific surface area played an important role on adsorption capacity, while the acidity of surface aluminol groups evaluated from acid-base titration curves contributed more to adsorption affinity and consequently the adsorption density.

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“…The XRD pattern of the product obtained by the reaction ofgibbsite (<0.2-~m particle size) in 1,3-propanediol is similar to that of ethylene glycol derivative of boehmite (Inoue et al, 1988) and can be indexed on the basis of boehmite structure (Reichertz and Yost, 1946;Christoph et aL, 1979). The 020 peak, ho~kever, appeared at a very low angle, whereas the 200 and 002 peaks occurred at the positions identical to boehmite.…”

Section: Xrd Profiles Of the Productsmentioning

confidence: 82%

“…For comparison, d-values ofboehmite (6.107 ,~; Christoph et al, 1979) and pseudoboehmire (prepared by the hydrolysis of aluminum isopropoxide) are also given in the same Figure. A comparison at a homogeneous series of compounds shows that the spacing increased with the increase in the molecular size of the solvent:…”

Section: Xrd Profiles Of the Productsmentioning

confidence: 99%

Formation of Organic Derivatives of Boehmite by the Reaction of Gibbsite with Glycols and Aminoalcohols

Inoue

Tanino

Kondo

et al. 1991

Clays and clay miner.

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Abstract--The reaction of gibbsite in various organic solvents at 2500--300"C under spontaneous vapor pressure of the solvents was examined. Glycols and aminoalcohols afforded the organic derivatives of boehmite in which one of the oxygen atoms of the glycol molecule or the alcoholic oxygen atom of aminoalcohol was incorporated into the boehmite layers. By increasing the molecular size of the solvent, the yield of the boehmite derivative decreased, and, at the same time, the basal spacing of the boehmite derivative increased. The product had a honeycomb texture on the surface of the particle, which suggests a dissolution-recrystallization mechanism for the formation of the boehmite derivatives. A hydroxyl group and a functional group, such as hydroxyl, methoxyl, or amino group having the ability to donate its lone pair electrons, were apparently necessary for the organic solvent molecules to form the boehmite derivative by this mechanism.

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The Crystal Structure of Boehmite

Cited by 100 publications

References 8 publications

Experimental Study on the Formation of Clay Minerals from Obsidian by Interaction with Acid Solution at 150° and 200°C

Experimental Study on the Formation of Clay Minerals from Obsidian by Interaction with Acid Solution at 150° and 200°C

Adsorption of phosphate at the aluminum (hydr)oxides–water interface: Role of the surface acid–base properties

Formation of Organic Derivatives of Boehmite by the Reaction of Gibbsite with Glycols and Aminoalcohols

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