Alkali metal ion exchange selectivity of Al-substituted tobermorite

Masamichi Tsuji, Sridhar Komarneni

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Abstract

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.

Original languageEnglish (US)
Pages (from-to)698-703
Number of pages6
JournalJournal of Materials Research
Volume4
Issue number3
DOIs
StatePublished - Jun 1989

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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