Structure and Behaviour of Aluminate Ions in Solution

Eremin, N I; Volokhov, Yu. A.; Mironov, V. E.

doi:10.1070/rc1974v043n02abeh001792

Cited by 46 publications

(37 citation statements)

References 6 publications

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“…Raman spectroscopy is a powerful tool for the study of inorganic species in solution 1- 4 and has been used on many occasions to investigate concentrated alkaline sodium aluminate solutions, [5][6][7][8][9][10][11][12][13][14][15][16] which are contained in many high level radioactive waste repositories, 7, 14 and which form the basis of the Bayer process used for the extraction of alumina from bauxitic ores. 17 It is well established 5- 16 that, apart from the various bands associated with NaOH(aq) and water, the Raman spectra of alkaline aluminate solutions at [Al(III)] T ≥ 0.5 M (where, here and throughout, the square brackets denote concentration and the subscript T signifies total or analytical values) show only one significant band, centred on ∼620 cm −1 .…”

Section: Introductionmentioning

confidence: 99%

Quantitative determination of an aluminate dimer in concentrated alkaline aluminate solutions by Raman spectroscopy

2006

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Raman spectra of concentrated alkaline aluminate solutions in various M'OH media (M'(+) = Na(+), K(+), Cs(+) and (CH(3))(4)N(+)) have been investigated systematically as a function of concentration and water activity, a(w). All spectra at [Al(III)](T) < or = 1 M and at 0.1 < or = [M'OH](T)/M < or = 5 (where the square brackets denote concentrations and the subscript T totals) exhibit one significant Raman mode in the low frequency region, at ca. 620 cm(-1), due to the symmetric Al(OH)(4)(-) stretch. At higher [Al(III)](T) and [M'OH](T) new modes appear at 530-550 and 700-720 cm(-1). The intensities of these new bands depend on [Al(III)](T) and a(w) but are independent of [OH(-)](T) and are only slightly cation-dependent. All three bands shift towards higher wavenumbers at [M'OH](T) > 10 M, probably due to ion-pairing. Spectra at [M'OH](T) < 10 M have been interpreted quantitatively by assuming that the integrated peak area of the 620 cm(-1) mode is linearly proportional to [Al(OH)(4)(-)] at constant a(w) and that the only significant equilibrium in these systems is the formation of a dimer that can be represented as (Al(OH)(4))(2)(2-)(aq), although it may exist in an oxo-bridged form such as [(HO)(3)Al-O-Al(OH)(3)](2). The (aquated) species Na(+), OH(-), Al(OH)(4)(-), the dimer, and their ion-pairs, were sufficient to interpret all the Raman observations. No evidence was found for various other species that have been claimed to exist in concentrated alkaline aluminate solutions.

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Section: Introductionmentioning

confidence: 99%

Quantitative determination of an aluminate dimer in concentrated alkaline aluminate solutions by Raman spectroscopy

2006

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“…This may lead to a significant local pH lowering in the vicinity of the anode which may cause the deposition of aluminum hydroxide and/or aluminum oxide. An important role of the processes of indirect deposition is circumstantially confirmed by the data [20][21][22] which indicates that the ratio (n) of OH -to aluminum ion concentrations determines the character of the hydrolytic processes. 3 ] n (OH) 2 -, the latter constituting also the colloid particles.…”

Section: Resultsmentioning

confidence: 83%

“…The contribution of the thermal decomposition of aluminate anions essentially depends on the pH value in nearelectrode region because, as is well-known, this process is reversible and amorphous aluminum hydroxide could dissolve with a generation of aluminate ions [20].…”

Section: Resultsmentioning

confidence: 99%

Plasma electrolytic ceramic-like aluminum oxide coatings on iron

et al. 2009

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The process characteristics of plasma-assisted electrochemical treatment of iron in aluminate electrolyte consisted of aqueous 0.1 M NaAlO 2 ? 0.05 M NaOH have been studied. It has been shown that in the range of DC voltages from 260 to 340 V, it is possible to deposit dense ceramic-like coatings with the thickness increased from 0.3-0.5 lm after 1 min deposition time to 25-30 lm for 1 h of deposition. The coatings were examined by X-ray diffractometry, Fourier-transformed infrared, X-ray photoelectron spectroscopy, scanning electron microscopy, and an electrochemical potentiodynamic voltammetry. It is shown that in pre-spark conditions (100-200 V) and on the initial stages of micro-arc anodizing the forming films contain, along with amorphous aluminum oxide/hydroxide, a substantial amount of iron oxide/hydroxide. The coatings obtained by micro-arc anodizing at 260-360 V for 10-60 min represent amorphous aluminum oxide with inclusions of crystalline corundum phase. The films with a thickness of 4-15 lm deposited at the anodizing voltage of 320-360 V exhibited the uniformity and good corrosion protection properties after sealing with common agents.

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“…Therefore, the effect of chloride ion on the stability of aluminium species was not the main factor producing higher hydrolysis rate of AlN compared with that in deionised water. Mashovets and Maltesv (1965), Puchkov et al (1971) and Eremin et al (1974) sodium aluminate complexes. These authors found that Na z had formed stronger complexes with aluminate ions than OH 2 .…”

Section: Effect On Hydrolysis Rate By Naclmentioning

confidence: 99%

Leaching process investigation of secondary aluminium dross: investigation of AlN hydrolysis behaviour in NaCl solution

Guo

Zhang

et al. 2012

Mineral Processing and Extractive Metallurgy

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The AlN hydrolysis behaviour in NaCl solution was investigated by immersing AlN powder in deionised water, 0?3 mol L 21 NaCl aq and 0?6 mol L 21 NaCl aq at 291 K respectively. The pH value of the suspension was monitored continuously for the first 4 days, and the amount of NH 3 formed within 10 days period was measured by water quality-determination of ammoniumdistillation and titration method. The characterisation of the products after hydrolysis was carried out using X-ray diffraction, SEM and TEM analyses. It was shown that the hydrolysis process included a slow reaction period involving the dissolution of aluminium hydroxide layer around raw AlN particle, followed by the precipitation of aluminium hydroxide gel and the crystallisation of boehmite, bayerite and gibbsite. The effects of sodium chloride concentration on the hydrolysis behaviour are presented.

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Structure and Behaviour of Aluminate Ions in Solution

Cited by 46 publications

References 6 publications

Quantitative determination of an aluminate dimer in concentrated alkaline aluminate solutions by Raman spectroscopy

Quantitative determination of an aluminate dimer in concentrated alkaline aluminate solutions by Raman spectroscopy

Plasma electrolytic ceramic-like aluminum oxide coatings on iron

Leaching process investigation of secondary aluminium dross: investigation of AlN hydrolysis behaviour in NaCl solution

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