TY - JOUR
T1 - Alkali metal ion exchange selectivity of Al-substituted tobermorite
AU - Tsuji, Masamichi
AU - Komarneni, Sridhar
N1 - Funding Information:
This research was supported by the Separation Processes Program, Division of Chemical and Process Engineering, National Science Foundation under Grant No. CBT-8619064.
PY - 1989/6
Y1 - 1989/6
N2 - 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 (αM N≡KM d/KN d,Kd: Distribution coefficient) for a combination of two cations at infinite dilution was proposed in terms of the selectivity coefficient (KM Na) which can be easily determined from the Kielland plot. An extremely large separation factor for Cs (αCs Na = 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.
AB - 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 (αM N≡KM d/KN d,Kd: Distribution coefficient) for a combination of two cations at infinite dilution was proposed in terms of the selectivity coefficient (KM Na) which can be easily determined from the Kielland plot. An extremely large separation factor for Cs (αCs Na = 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.
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U2 - 10.1557/JMR.1989.0698
DO - 10.1557/JMR.1989.0698
M3 - Article
AN - SCOPUS:0024656688
SN - 0884-2914
VL - 4
SP - 698
EP - 703
JO - Journal of Materials Research
JF - Journal of Materials Research
IS - 3
ER -