Na/K, Na/Mg, and Na/Ca exchange isotherms have been experimentally determined for the FEBEX bentonite. Na-homoionized FEBEXbentonite was reacted at room temperature with mixedsalt dissolution of NaCl/KCl, NaCl/MgCl2, or NaCl/CaCl2, while keeping a total cation normality of 0.5 eq L-1. Isotherm exchange experiments were performed using ten (duplicated)experimental points, which cover the complete range of the corresponding binary equivalent fractions. Results indicate that for the Na/K exchange reaction, Vanselow coefficients are larger than one, what is in agreement with the tendency of the smectite of having greater affinity for K than for Na. The exchange constant decreases as K progressively replaces Na in the smectite. This tendency ends when the equivalent fraction of potassium, E K, reaches a value of around 0.250.3. From this point to higher K contents, it remains nearly constant irrespective of E K but slightly decreasing again at values near one. The Vanselow selectivity coefficient for the Na/Mg isotherm indicates a preference for the divalent cation. It is nearly constant (Kv ≍ 5.6) for E Mg < 0.6, but increases up to 10.2 for a nearly Mg-saturated smectite.
The Na/Ca exchange resembles that of Na/Mg, although the selectivity coefficients are larger (Kv ≍ 7.0 for E Ca < 0.6). The comparison of the selectivity coefficients for the Na/Mg and Na/Ca exchange reactions indicates that the smectite has a slightly higher affinity for Ca than for Mg. This result is consistent with those observed for the Wyoming bentonite.
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J. Linares, F. Huertas, M. Lachica, and E. Reyes, Proc. Intl. Clay Conf., 1, 351, (1972)
E. Caballero, M. Fernandes Porto, J. Linares, F. Huertas, and E. Reyes, Est. Geol. 39, 121 (1983)
G. Leone, E. Reyes, G. Cortecci, A. Pochini, and J. Linares, Clay Miner. 18, 227 (1983)
J.M. Fernández Soler, PhD. Thesis, University of Granada, 1992
J. Linares, F. Huertas, E. Reyes, E. Caballero, E. Barahona, J.L. Guardiola, J. Yáथez, E. Romero, and A. Delgado, ENRESA Technical Report 01/93, Madrid, 1993
ENRESA, Technical Report 09/97, ENRESA, Madrid, 1997.
L. Shapiro, US Geol. Surv. Bull., 1401, 76 (1975)
Soil Conservation Service, Soil Survey Laboratory Methods and Procedure for Collecting Soil Samples, U.S.D.A., Washington DC, 1972
G. Sposito, The Thermodynamics of Soil Solutions (Oxford University Press, New York), 1981
T.J. Wolery, Report No. URCL-MA-110662 PT III, Lawrence Livermore National Laboratory, 1992
G. Sposito, The Surface Chemistry of Soils (Oxford University Press, New York), 1984
M.G.M. Bruggenwert, and A. Kamphorst, in Soil Chemistry. 5-B. Physico-chemical Models, edited by G.H. Bolt (Elsevier, Amsterdam), p. 141, 1983
P. Fletcher, G. Sposito, and C.S. LeVesque, Soil Sci. Soc. Am. J. 48, 1016 (1984)
F.J. Huertas, J. Cuadros, and J. Linares, Appl. Geochem. 10, 347 (1995)
I. Shainberg, and A. Kaiserman, Soil Sci. Soc. Am. J. 33, 547 (1969)
K. Verburg and P. Baveye, Clays Clays Miner. 42, 207 (1994)
D.L. Suarez, and M.F. Zahow, Soil Sci. Soc. Am. J. 53, 52 (1989)
A.P. Vanselow, Soil Sci. 33, 95 (1932)
E.N. Gapon, J. Gen. Chem. 3, 144 (1933)
G.L. Gaines, and H.C. Thomas, J. Chem. Phys. 21, 714 (1953)
C.A.J. Appelo, and D. Postma, D., Geochemistry, Groundwater and Pollution (Ed. Balkema, Rotterdam), 1993
P. Fletcher, Chemical Thermodynamics for Earth Scientists (Longman Eds., Burt Mill), 1993
J. Delgado, P. Carretero, R. Juncosa, J. Samper, F.J. Huertas, C. Jiménez de Cisneros, E. Caballero, F. Huertas, J. Linares, in this volume
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Huertas, F.J., Carretero, P., Delgado, J. et al. Ion Exchange Behavior of the Febex Bentonite. 1. Na/K, Na/Mg and Na/Ca Experimental Exchange Isotherms. MRS Online Proceedings Library 663, 589 (2000). https://doi.org/10.1557/PROC-663-589