An experimental study of granitic water-saponitic bentonite interaction under hydrothermal conditions
- Universidad Autonoma de Madrid (Spain)
The interaction of a saponitic clay from the Madrid Basin with synthetic groundwater (GW) simulating those from granitic areas is investigated. The experiments performed explore the reaction of clay with GW (1:3 solid to water ratio) at 45, 60 and 90{degrees}C. Water extracted from the clay slurries has been analyzed and water of this composition synthesized again to run a new reaction with the original clay (salt concentration process). The clay product of the first reaction was reacted again with GW (leaching process). These reactions were repeated in successive equilibrating steps. Multicationic selectivity coefficients have been calculated. K > Ca > Mg > Na is the order of preference for adsorption by the clay. The selectivity of Ca is highly enhanced in both processes, the clay acting as a true complexing agent for Ca, as calcite controls the carbonate equilibrium. A clear dependence of the exchange constants on temperature with the range explored was not detected. The GW composition evolves from Ca,Na-HCO{sub 3}, to Na,Mg-HCO{sub 3}, (leaching) and NaCl (concentration), the solutions being buffered at pH 8.0. Mechanical properties, clay mineralogy and bulk adsorption properties remained virtually unchanged in the successive one month experiments although a slight decrease in BET specific surface area indicated some sepiolite dissolution at 90{degrees}C.
- OSTI ID:
- 47940
- Report Number(s):
- CONF-931108-Vol.333; TRN: 95:011447
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 29 Nov - 3 Dec 1993; Other Information: PBD: 1994; Related Information: Is Part Of Scientific basis for nuclear waste management XVII; Barkatt, A. [ed.] [Catholic Univ. of America, Washington, DC (United States)]; Van Konynenburg, R.A. [ed.] [Lawrence Livermore National Lab., CA (United States)]; PB: 964 p.
- Country of Publication:
- United States
- Language:
- English
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