The dissolution rates of gibbsite in the presence of chloride, nitrate, silica, sulfate, and citrate in open and closed systems at 20°C

M. Dietzel, G. Böhme

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Abstract

The dissolution of well crystallized gibbsite far at from equilibrium was studied in batch and mixed flow through reactors. The dissolution experiments were carried out between pH 2 and 6 in the presence of 10 mmol L-1 citrate, at pH 2 and 3 in the presence of 10 mmol L-1 chloride, nitrate, and sulfate, and at pH 2 and 3 in the presence of 1.5 mmol L-1 silica at 20°C. The dissolution rate of gibbsite, RAl (mol m-2 s-1), increases in the order of chloride ≈ nitrate < silica < sulfate ≈ citrate. In presence of silica, sulphate, and citrate dissolution is catalysed by the formation of aluminium complexes at the gibbsite surface (pH 2 and 3). From pH 2 to 3 no effect of RAl on hydrogen activity is predicted as singly coordinated surface sites at the edges of the platy gibbsite crystals, [≡AlOH2 +0.5] ≈ [≡AlOH], are almost saturated with protons. However at pH >3 dissolution is slowed by a decrease of [≡AlOH2+0.5]. Gibbsite dissolution rates measured in closed and open systems were identical within the experimental and analytical uncertainty. This observation indicates that gibbsite dissolution is a surface controlled process. If dissolution of gibbsite occurs close to equilibrium RAl values may be predicted by an approximately linear function of ΔGr.

Original languageEnglish
Pages (from-to)1199-1211
Number of pages13
JournalGeochimica et Cosmochimica Acta
Volume69
Issue number5
DOIs
Publication statusPublished - 1 Mar 2005

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gibbsite
Citric Acid
Silicon Dioxide
Nitrates
Sulfates
Chlorides
Dissolution
silica
dissolution
chloride
sulfate
nitrate
Open systems
rate

ASJC Scopus subject areas

  • Geochemistry and Petrology

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The dissolution rates of gibbsite in the presence of chloride, nitrate, silica, sulfate, and citrate in open and closed systems at 20°C. / Dietzel, M.; Böhme, G.

In: Geochimica et Cosmochimica Acta, Vol. 69, No. 5, 01.03.2005, p. 1199-1211.

Research output: Contribution to journalArticleResearchpeer-review

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