Small-Angle X-Ray Scattering from Hydrolyzed Aluminum Nitrate Solutions

Rausch, W.; Bale, Harold D.

doi:10.1063/1.1725011

Cited by 78 publications

(32 citation statements)

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“…After six months of aging at room temperature, the solution reaches a state that appears to be close to equilibrium. The scattering pattern observed after six months of aging at room temperature is similar to that obtained from a sample aged for 2h at 343 K and is consistent with that expected from a solution of A113 ions (Rausch & Bale, 1964;Schaefer et al, 1986).…”

Section: A Qualitative Findinqssupporting

confidence: 68%

“…These solutions are uniformly clear in appearance. However, previous studies have suggested that the aluminium hydroxide species in the solution undergo an interesting and quite distinct aggregation process that finally, after several months of aging at room temperature, returns to a solution of noninteracting AI~3 ions (Rausch & Bale, 1964). The same study showed the final stable solution can apparently be reached within a period of 2h if the sample temperature is increased to 343 K. Although earlier work has established some of the qualitative features of the aggregation process, little is known about the details of the behavior.…”

Section: ! Introductionmentioning

confidence: 99%

“…The AI t 3 ion and the dimer have been found to exist by X-ray crystallography of the corresponding surface salts. Rausch & Bale (1964)successfully identified the Al~3 ion in alumina solutions by using small-angle X-ray scattering (SAXS) techniques. Schaefer, Shellman, Keefer & Martin (1986) confirmed the existence of the All 3 ion using the same technique.…”

Section: ! Introductionmentioning

confidence: 99%

“…The AI t 3 ion and the dimer have been found to exist by X-ray crystallography of the corresponding surface salts. Rausch & Bale (1964) …”

mentioning

confidence: 99%

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Aggregation in aluminium hydroxide solutions investigated by small-angle X-ray scattering

Kumru¹,

Bale²

1994

J Appl Cryst

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Aluminium hydroxide particles, created by hydrolysis of aluminium nitrate solutions with sodium carbonate, aggregate rapidly to form mass fractal structures for which the fractal dimension varies from 1.7 to 2.1 depending on the OH/Ai-ion ratio of the solution. This system has been studied by small-angle X-ray scattering (SAXS). The OH/AI ratios for the solutions were 1.5, 2.0 and 2.15. The maximum radius of gyration of the aggregates of about 50 A is found in the solutions having the highest OH/AI ratio. SAXS measurements made at various stages of the aging process show that, in addition to fractal aggregation, there is a second process active in the solutions that leads to the break up of the fractal structure and formation of nonfractal particles, which are probably All3 ions, [AIOgAII2(OH)z4(OH2)t2] 7+. This process, which is strongly temperature dependent, is governed by an activation energy of approximately 162 kJ mol-i !. IntroductionThe self-assembling of subunits to form aggregates is a phenomenon that has been widely studied during the past decade. This remarkable interest is due in part to the discovery that many systems show universality features characteristic of fractal aggregation (Brinker & Scherer, 1990;Martin & Hurd, 1987).When dissolved in water, metal cations are solvated by water molecules. A partial charge transfer from the water molecule to the metal ion can occur during this solvation process, which is called hydrolysis. For aluminium, for example, the AI 3+ ion has a coordination number of 6 and exists as the unhydrolyzed species [AI(OH2)6] 3+ below pH = 3 (Baes & Mesmer, 1976 (2) In this case, r is also the OH/Ai ion ratio. The electric charge of the aluminium monomer can range from +3 (unhydrolyzed) to -I on [Ai(OH)4(OHz)2]-, the dominant monomer at pH > 6. The formation of most polynuclear species results from the unusual tendency of OH-among simple ligands to form binding linkages between two or more cations. Such reactions involve, as well as the loss of a bound water molecule, the rupture of an M-OH z bond; and this is likely to be a much slower process than the formation of the monomer. For aluminium, a basic condensation model that assumes that the condensation reaction proceeds along pathways that maximize hydrogen bonding has been developed by Wood (1990). A dimer, [AI2(OH)2(OH2)8] 4+, is formed by an edge being shared between two octahedral forms of singly hydrolyzed monomers (r = 1). The addition of a third r = 1 monomer occurs preferentially to form the [Ai3(tri_p_OH)(OH)3(OH2)9] 5 + trimer, where the notation tri-l~-OH emphasizes that the OH ligand bridges three aluminium hydroxide molecules. The actual polynuclear species present in the solution depend quite strongly on the concentration of the reactants, the pH of the solution and the temperature and even on the age of the solution. Consequently, it is difficult to specify the actual species present for a given set of preparation conditions. The potentiometric results of Baes & Mesmer (1976) indicate that bothand ...

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Section: A Qualitative Findinqssupporting

confidence: 68%

Section: ! Introductionmentioning

confidence: 99%

Section: ! Introductionmentioning

confidence: 99%

“…The AI t 3 ion and the dimer have been found to exist by X-ray crystallography of the corresponding surface salts. Rausch & Bale (1964) …”

mentioning

confidence: 99%

See 2 more Smart Citations

Aggregation in aluminium hydroxide solutions investigated by small-angle X-ray scattering

Kumru¹,

Bale²

1994

J Appl Cryst

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“…Traditional methods include potentiometric titration [4], Al-Ferron timed spectrophotometric assay [5,6] and 27 Al nuclear magnetic resonance ( 27 Al NMR) spectroscopy [7,8]. In addition, X-ray diffraction [9], Raman spectroscopy [10] and X-ray photoelectron spectroscopy [11] are used as aluminum speciation analysis. Al-Ferron assay and 27 Al NMR spectroscopy were common means to identify aluminum speciation of coagulant.…”

Section: Introductionmentioning

confidence: 99%

Aluminum speciation of coagulants with low concentration: Analysis by electrospray ionization mass spectrometry

Zhao

Liu

2011

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Fractal Geometry Approach to Describe Mesostructured Boehmite and Gamma‐Alumina Nanorods

Rashidi

Kharat

Rashidi³

et al. 2010

Eur J Inorg Chem

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Mesoporous boehmite and gamma-alumina with nanorodlike morphology, exhibiting a high surface area and large pore volume, have been prepared by a nonsurfactant-templating sol-gel technique with a simple precursor system, aluminum isopropoxide, ethanol, 2-propanol, or 2-butanol as solvents, and sulfuric or hydrochloric acid as peptizing agents. The effect of the solvent-type and the peptizing agent were studied, and optimum conditions were deter-

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Small-Angle X-Ray Scattering from Hydrolyzed Aluminum Nitrate Solutions

Cited by 78 publications

References 4 publications

Aggregation in aluminium hydroxide solutions investigated by small-angle X-ray scattering

Aggregation in aluminium hydroxide solutions investigated by small-angle X-ray scattering

Aluminum speciation of coagulants with low concentration: Analysis by electrospray ionization mass spectrometry

Fractal Geometry Approach to Describe Mesostructured Boehmite and Gamma‐Alumina Nanorods

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