Cation Exchange Selectivity Coefficient Values on Smectite and Mixed-Layer Illite/Smectite Minerals

2009 ◽  
Vol 73 (3) ◽  
pp. 928-942 ◽  
Author(s):  
Christophe Tournassat ◽  
Hélène Gailhanou ◽  
Catherine Crouzet ◽  
Gilles Braibant ◽  
Anne Gautier ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Mixed Layer ◽  
Selectivity Coefficient ◽  
Exchange Selectivity

Am3+ and Eu3+ /alkali cation exchange selectivity on mordenite and zeolite L

2000 ◽  
Vol 15 (12) ◽  
pp. 2849-2856 ◽  
Author(s):  
Masamichi Tsuji ◽  
Hitoshi Mimura
Keyword(s):  
Ion Exchange ◽  
Cation Exchange ◽  
Selectivity Coefficient ◽  
Alkali Cation ◽  
Ionic Form ◽  
Alkali Cations ◽  
Ionic Radii ◽  
Zeolite L ◽  
Exchange Site ◽  
Exchange Selectivity

Am3+ and Eu3+ /alkali cation exchange selectivity was studied on mordenite and zeolite L at 25 to 60 °C to examine the effect of their openings of ion-exchange sites. The corrected selectivity coefficient at the infinitesimal exchange increased in the order of Eu3+ < Am3+ on mordenite and Am3+ < Eu3+ on zeolite L. The selectivity reversal did not reflect the effect of the ionic form, but reflected the dimension of the opening of the ion-exchange site and charge of trivalent cations, since the crystal ionic radii of alkali cations were much smaller than the openings of these zeolites (7–8 Å).

Cation exchange selectivity of layered titanates, H2Ti3O7

1985 ◽  
Vol 60 (2) ◽  
pp. 264-267 ◽  
Author(s):  
H. Izawa ◽  
S. Kikkawa ◽  
M. Koizumi
Keyword(s):  
Cation Exchange ◽  
Exchange Selectivity

Cation exchange selectivity in aqueous-organic solvent mixtures, and solvation in the external phase

1976 ◽  
Vol 48 (3) ◽  
pp. 458-464 ◽  
Author(s):  
Robert. Smits ◽  
Desire L. Massart ◽  
Jean. Juillard ◽  
Jean P. Morel
Keyword(s):  
Organic Solvent ◽  
Cation Exchange ◽  
Solvent Mixtures ◽  
External Phase ◽  
Exchange Selectivity

Hofmeister Effects on Cation Exchange Equilibrium: Quantification of Ion Exchange Selectivity

2013 ◽  
Vol 117 (12) ◽  
pp. 6245-6251 ◽  
Author(s):  
Xinmin Liu ◽  
Hang Li ◽  
Wei Du ◽  
Rui Tian ◽  
Rui Li ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Cation Exchange ◽  
Exchange Equilibrium ◽  
Exchange Selectivity

AN INVESTIGATION ON THE DEPENDENCE OF THE GAPON COEFFICIENT ON EXCHANGEABLE SODIUM BY THREE LINEAR TRANSFORMATIONS

1988 ◽  
Vol 68 (4) ◽  
pp. 813-820
Author(s):  
V. P. EVANGELOU ◽  
F. J. COALE
Keyword(s):  
Clay Minerals ◽  
Limited Range ◽  
Selectivity Coefficient ◽  
Sodium Adsorption Ratio ◽  
Exchangeable Sodium ◽  
Linear Transformations ◽  
Laboratory Staff ◽  
Soil Systems ◽  
Exchange Adsorption ◽  
Exchange Selectivity

Based on theorical considerations of ideal exchangers, the traditional Gapon exchange selectivity coefficient (KG) is generally not expected to remain constant for exchangeable sodium ratio (ESR) greater than 0.20. Therefore, the ESR-SAR (SAR=sodium adsorption ratio) relationship is only expected to be linear and predictable for this limited range of exchange sites. The purpose of this study is to demonstrate that for some soils and/or clay minerals, which are considered nonideal exchangers, the KG may remain constant for ESR values greater than 0.20. This information is important for the reclamation of sodic soil systems with ESR > 0.2 to near Na+ saturation. Experimental data in the literature is most often limited in the ESR range of 0 – 1. Experimental Na+-Ca2+ exchange data for each of a number of soils and clay minerals were plotted according to three linear transformations of the Gapon expression in order to determine if a particular soil or clay mineral exhibits a constant Gapon exchange selectivity coefficient (KG) for ESR values significantly greater than 0.20. The three linear transformations are represented by plots of (1) 1/ExNa vs. 1/SAR, (2) ExNa vs. ExNa/SAR and (3) SAR/ExNa vs. SAR (ExNa = exchangeable Na). From the three plots employed, the ExNa vs. ExNa/SAR and the SAR/ExNa vs. SAR were shown to be the most applicable in predicting a constant KG for ESR values greater than 0.20. It is also shown that some generally low CEC materials may exhibit a constant KG for ESR values significantly greater than 0.20. These data also infer that for a particular soil the linearity of the widely used ESR-SAR relationship introduced by the U.S. Salinity Laboratory Staff may not be limited to an ESR value of 0.20. Key words: Exchangeable sodium percentage, sodium adsorption ratio, thermodynamics of cation exchange, adsorption maxima, ion affinity constants.

Na/Ca selectivity coefficients of montmorillonite in perchlorate solution at different temperatures

2012 ◽  
Vol 1475 ◽  
Author(s):  
Aku Itälä ◽  
Arto Muurinen
Keyword(s):  
Cation Exchange ◽  
Spent Nuclear Fuel ◽  
Spent Fuel ◽  
Selectivity Coefficients ◽  
Crystalline Bedrock ◽  
Bentonite Buffer ◽  
Different Temperatures ◽  
C 50 ◽  
Exchange Selectivity

ABSTRACTThe Finnish spent nuclear fuel disposal is based on the Swedish KBS-3 concept in crystalline bedrock. The concept aims at long-term isolation and containment of spent fuel in copper canisters surrounded by bentonite buffer which mostly consists of montmorillonite. For the long-term modelling of the chemical processes in the buffer, the cation-exchange selectivity coefficients have to be known at different temperatures. In this work, the cation-exchange selectivity coefficients and cation-exchange isotherms were determined in batch experiments for montmorillonite at three different temperatures (25 °C, 50 °C and 75 °C). Five different ratios of NaClO4/Ca(ClO4)2 were used in the experimental solutions. After equilibration the solution and montmorillonite were separated and the solution analysed to get the desired exchange parameters. The experiments were modelled with a computational model capable of taking into account the physicochemical processes that take place in the experiment.

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