Study of leaching mechanisms of ions incorporated in cement or polymer
The leaching kinetics of inactive Cs from cylindrical cement specimens containing Cs(2)SO(4) have been studied at different temperatures and thicknesses. In all cases the root(t) plots were reasonably linear, at least initially, in accordance with Fick's law, and the diffusion coefficients could be estimated. Leaching of specimens containing Sr-90 and NaNO(3) was performed under exposure to atmospheric CO(2). Low-temperature differential scanning calorimetry measurements of hydrated cement were undertaken to obtain information about the melting behaviour, and hence the state, of water within the cement. Mercury porosimetry was also carried out using representative cement specimens which had been subjected to leaching. The sorption of Cs ions from aqueous solution by cement was studied by equilibrating cement granules with aqueous Cs(2)SO(4) solutions. Cellulose films containing CaSO(4) or SrSO(4) were leach tested in frequently renewed water at 25 C. The elution curves followed a root(t) law in conformity with the Higuchi equation. Elution tests of NaCl or SrSO(4) embedded in epoxy resin were performed. The SrSO(4) elution behaviour was generally similar to that exhibited by cellulose. A new, sophisticated model capable of describing the elution of a soluble salt, with simultaneous imbition of water by the matrix was formulated. Computations specifically representative of the cellulose acetate-NaCl system showed that the model can interpret, at least semiquantitatively, the observed elution behaviour.
Bibliographic Reference: EUR 13543 EN (1991) 90 pp., FS, ECU 8.75
ISBN: ISBN 92-826-2770-5
Record Number: 199111024 / Last updated on: 1994-12-02
Original language: en
Available languages: en