Dielectric relaxation of concentrated alkaline aluminate solutions

Buchner, Richard and Sipos, Pal and Hefter, Glenn and May, Peter M. (2002) Dielectric relaxation of concentrated alkaline aluminate solutions. JOURNAL OF PHYSICAL CHEMISTRY A, 106 (28). pp. 6527-6532. ISSN 1089-5639

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Abstract

The complex dielectric permittivity of concentrated aqueous alkaline aluminate solutions at total concentrations 1 less than or similar to [Al](T)/mol dm(-3) less than or similar to 6 with either [Na](T) 8.33 mol dm(-3) or [Al](T)/[Na](T) = 0.750 has been determined at 25 degreesC in the frequency range 0.5 less than or similar to v/GHz less than or equal to 20. All solution spectra could be represented as a superposition of a Cole-Cole relaxation-time distribution for the solvent relaxation with an additional low-frequency Debye dispersion assigned to the solute. The variation of the effective hydration number, deduced from the water dispersion amplitude, shows that the aluminate ion, Al(OH)(4)(-), is less strongly solvated than the hydroxide ion, OH-. Additionally, a "melting" of the hydration shells is observed at high concentration, probably due to co-sphere overlap and/or packing effects. The features of the solute relaxation are consistent with solvent-shared ion pairs of Na+ with a previously proposed dimeric anion, [(HO)(3)Al-O-Al(OH)(3)](2-). However, the data are not sufficient for an unequivocal assignment.

Item Type: Article
Uncontrolled Keywords: WATER; NACL;
Subjects: 500 Science > 540 Chemistry & allied sciences
Divisions: Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > PD Dr. Richard Buchner
Depositing User: Dr. Gernot Deinzer
Date Deposited: 12 Oct 2021 10:11
Last Modified: 12 Oct 2021 10:11
URI: https://pred.uni-regensburg.de/id/eprint/40078

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