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

Alkali metal ion exchange selectivity of Al-substituted tobermorite

1989 ◽  
Vol 4 (3) ◽  
pp. 698-703 ◽  
Author(s):  
Masamichi Tsuji ◽  
Sridhar Komarneni
Keyword(s):  
Ion Exchange ◽  
Alkali Metal ◽  
Cation Exchange ◽  
Separation Factor ◽  
Metal Ion ◽  
Infinite Dilution ◽  
Exchange Reactions ◽  
Alkali Metal Ion ◽  
Metal Ion Exchange ◽  
Exchange Selectivity

Alkali metal ion exchange isotherms at a total ionic strength of 0.001 M were determined at 25 °C on a 1.13 nm anomalous [Al3+ + Na+]-substituted tobermorite with the formula, Ca5Na0.75Al0.9Si5.1O16(OH)2 · 6.03H2O. The Kielland plots of Na+/K+, Na+/Rb+, and Na+/Cs+ exchange reactions showed straight lines. The slopes were steeper for Cs+ and Rb+ exchange reactions, as compared to K+ exchange. The cation-exchange selectivity for alkali metals was found to increase as follows: Cs+>Rb+>K+>Na+. A new evaluation method of the separation factor (αMN/KMd/KNd,Kd: distribution coefficient) for a combination of two cations at infinite dilution was proposed in terms of the selectivity coefficient (KMNa) which can be easily determined from the Kielland plot. An extremely large separation factor for Cs (αCsNa = 112) was found at infinite dilution. These basic studies of cation exchange selectivity are of relevance in cation separation and purification and nuclear waste disposal.

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).

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