ZnO dissolution kinetics by means of a Zn-65-tracer

O. Frühwirt, G.W. Herzog, I. Hollerer, G. Reitsamer

    Publikation: Beitrag in FachzeitschriftArtikel


    The dissolution kinetics of ZnO single crystals in 0.1 M acetate buffer and 0.1 M boric acid was investigated. A special measurement device has been set up for continuously monitoring the concentration of dissolved Znsup(2+). ZnO was activated by thermal neutrons (ASTRA-Reactor, Seibersdorf) to get trace amounts of the $gamma active nuclide sup6sup5Zn. Irradiation- induced defects of the crystal lattice were annealed by heat treatment at 500sup(o)C. The irradiated ZnO crystals were fixed to a rotating-disc system, which enabled kinetic experiments of the dissolution reaction with respect to diffusion control. The dissolution of ZnO could be shown to be diffusion controlled in boric acid and transfer controlled in acetate buffer. This different kinetic behaviour can be explained by the dependence of the saturation concentraion of Znsup(2+) on the pH value. In acetate buffer (pH 4.6) the saturation of Znsup(2+) is high and is almost unaltered by the ZnO dissolution. The transport from the phase boundary into the solution is faster than the phase reaction. In unbuffered boric acid (pH 5.1) the saturation of Znsup(2+) is lower and decreases steadily because the pH valueis increased by ZnO dissolution. In this case the transport of Znsup(2+) is slower than the phase reaction. Using the results of the kinetic measurements a value for the solubility product could be established, which is in good agreement with the value given in literature for thermodynamically inactive ZnO. (Author)
    Seiten (von - bis)43-50
    FachzeitschriftSurf. Technol.(1982)
    PublikationsstatusVeröffentlicht - 1982

    Research Field

    • Nicht definiert


    • FZS-000CHP


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