No abstract

No abstract

Prediction of the migration rates of ions in geologic formations is of extreme importance in the fields of nuclear waste disposal and enhanced oil recovery. Demonstration of the safety of nuclear waste repositories requires that the repository be so designed and situated that migration rates from the repository be acceptably low in the event of water flow through the repository. On the other hand, the principal criterion for selection of tracers to monitor fluid flow in the flooding techniques of enhanced oil recovery is that the tracers be not retained on the formation, i.e., migration rates must be high. Migration rates are dependent on the distribution coefficient of the species between fluid and the geologic media such that the greater the distribution coefficient the slower the rate of migration. Therefore, for reliable prediction of migration rates, accurate knowledge of the adsorption behavior of the nuclides and tracers must be known as a function of all of the pertinent variables.Obtaining the necessary data for this complex situation is complicated by both the large number of different minerals which may be present and the wide range of solution compositions. In order to accumulate a systematic body of information pertinent to this complex situation, we are measuring adsorption of ions of interest on minerals typical of classes, from a wide range of aqueous solution compositions. Initially, montmorillonite was selected for attention because its high adsorptive capacity for ions may cause it to dominate the adsorptive proportion of the formation in which it is present. Reported here are distribution coefficients of alkali metal and alkaline earth ions, and of one rare earth, between montmorillonite predominantly in the sodium and calcium forms and aqueous solutions of controlled pH, at moderate to high salinities (>0.01MNaCl). The ions were selected for initial study, not only because of their intrinsic interest for these applications but also because they allow evaluation of the extent to which equilibria can be described by conventional ion-exchange equations with minimum difficulties from hydrolysis, precipitation, and complexing. Correlation of results as a 0-8412-0498-5/79/47-100-297$07.00/0

No abstract

No abstract