An experimental study of dolomite dissolution rates at 80°C as a function of chemical affinity and solution composition

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doi: 10.1016/j.chemgeo.2007.05.008
Authors:Gautelier, Maud; Schott, Jacques; Oelkers, Eric H.
Author Affiliations:Primary:
Université Paul Sabatier, Géochimie et Biogéochimie Experimentale, Toulouse, France
Volume Title:Chemical Geology
Source:Chemical Geology, 242(3-4), p.509-517. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541
Publication Date:2007
Note:In English. 53 refs.; illus., incl. 3 tables
Summary:Steady-state dissolution rates of Haute Vallee de l'Aude dolomite were measured as a function of chemical affinity and aqueous solution composition in mixed-flow reactors at 80 °C. Experiments were performed in HCl-NaHCO3 bearing aqueous solutions with in-situ pH ranging from 6.36 to 7.17. Rates are found to be a strong function of aqueous carbonate concentrations at far-from-equilibrium conditions. Measured rates can be described using the dissolution mechanism of Pokrovsky and Schott [Pokrovsky, O.S., Schott, J., 2001. Kinetics and mechanism of dolomite dissolution in neutral to alkaline solutions revisited. Am. J. Sci., 301, 597-626] where rates are controlled by the detachment of the >MgOH2+ species at the dolomite surface. Within this mechanism, dolomite dissolution rates can be described using r = kMg+{KCO3*KCa*/KCO3*KCa*+KCa*aCO32- + aC032--aCa2+}n(1-exp(-nA/RT))where r refers to the overall BET surface area normalized dolomite dissolution rate at both near and far-from-equilibrium conditions, kMg+ designates a rate constant equal to 4.0×10-12 mol cm-2 s-1, KCa* and KCO3* denote equilibrium constants equal to 3.5×10-5 and 4.5×10-5, respectively, ai refers to the activity of the subscripted aqueous species, A corresponds to the chemical affinity of the dissolving dolomite, R represents the gas constant, T symbolizes absolute temperature and n designates a stoichiometric coefficient equal to 1.9. Abstract Copyright (2007) Elsevier, B.V.
Sections:Environmental studies; Experimental mineralogy
Subsections:Non-silicates
Subjects:Carbon; Carbon dioxide; Carbon sequestration; Carbonates; Chemical composition; Chemical reactions; Dolomite; Experimental studies; Geochemistry; Kinetics; Mathematical methods; PH; Solution; Stoichiometry; Temperature; Weathering; Aude France; Europe; France; Western Europe
Abstract Numbers:07M/3635
Record ID:2008016701
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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