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A hydrogen electrode study of concentrated alkaline aluminate solutions

Sipos, P., Hefter, G. and May, P.M. (1998) A hydrogen electrode study of concentrated alkaline aluminate solutions. Australian Journal of Chemistry, 51 (6). pp. 445-453.

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A detailed study of highly concentrated aqueous alkaline aluminate solutions has been made by hydrogen electrode potentiometry in cells with liquid junction at 25°C in 8 M Na(ClO4) media. Measurements were performed over the total concentration ranges 0.1 M < [NaOH]T < 4-0 M and 0.02 M < [AlIII]T < 3.2 M, and at total concentration ratios of 6.92 ≥ [OH-]T/[AlIII]T ≥ 4.3. Nernstian electrode behaviour was observed at [NaOH]T ≤ c. 2 M in pure NaOH/NaClO4 mixtures. At low [AlIII]T the data were consistent with the formation of only the well known Al(OH)4-(aq) species but there is clear evidence of a systematic release of hydroxide as [AlIII]T and [NaOH]T increase. The data are consistent with the formation of polymeric aluminate complexes having a stoichiometry of Alq(OH)3q-rr+= (q = 4-7, q + r = 1 or 2). However, unequivocal identification of these species is difficult on account of strong correlations in the data and the possible effects of ion-pairing.

Item Type: Journal Article
Murdoch Affiliation: School of Chemical and Mathematical Science
Publisher: Commonwealth Scientific and Industrial Research Organization Publishing
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