Ion exchange in mordenite
- 1 January 1974
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 70, 2362-2367
- https://doi.org/10.1039/f19747002362
Abstract
Ion-exchange isotherms have been measured for synthetic mordenite involving the cation pairs Na+⇌Cs+, NH+ 4⇌K+, NH+ 4⇌Na+, NH+ 4⇌Li+, 2NH+ 4⇌Ca2+, 2NH+ 4⇌Sr2+ and 2NH+ 4⇌Ba2+. In all cases except those involving Ca2+ and Sr2+ reversible exchange was effected. The values of the thermodynamic equilibrium constant, Ka, and the standard free energy of exchange, ΔG⊖, were calculated for the reversible pairs. For additional combinations of the reversible ionic pairs, Ka and ΔG⊖ were obtained using the triangle rule. The thermodynamic affinity sequence is Cs+ > K+ > NH+ 4 > Na+ > Ba2+ > Li+. The thermodynamic affinity sequence among monovalent alkali metal ions established in this work for mordenite was found to be repeated for other zeolites, provided exchanges which do not go to completion are normalised by considering the equilibrium only in terms of the exchangeable fraction of the ions.Keywords
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