SODIUM, CALCIUM, AND AMMONIUM EXCHANGE ON CLINOPTILOLITE FROM THE FORT-LACLEDE DEPOSIT, SWEETWATER COUNTY, WYOMING

Clinoptilolite from the Fort LaClede deposit in Sweetwater County, Wyoming, shows a moderate selectivity for NH//4** plus over Na** plus in aqueous solution. At 30 degree C, the standard free energy of this replacement reaction is minus 0. 7 kcal/mole at an ionic strength of 0. 05 M and minus 0. 8 kcal/mole at 0. 5 M. The Na** plus -NH//4** plus exchange is complete within 3 days in agitated solution and proceeds to the same extent from the clinoptilolite saturated with either cation. The Ca**2** plus -Na**30 exchange also is complete within 3 days in agitated aqueous solution and proceeds to the same extent from either the calcium or the sodium form of the zeolite. Using test methods which take into account the slower equilibration of Ca**2** plus -loaded clinoptilolite, the cation-exchange capacity is substantially the same over the full range of loading by Ca**2** plus and Na** plus .