Sodium, Calcium, and Ammonium Exchange on Clinoptilolite from the Fort Laclede Deposit, Sweetwater County, Wyoming

Abstract

Abstract--Clinoptilolite from the Fort LaClede deposit in Sweetwater County, Wyoming, shows a moderate selectivity for NH~-over Na + in aqueous solution. At 30~ the standard free energy of this replacement reaction is -0.7 kcal/mole at an ionic strength of 0.05 M and -0.8 kcal/mole at 0.5 M. The Na+-NH4 + exchange is complete within 3 days in agitated solution and proceeds to the same extent from the clinoptilolite saturated with either cation.The Ca2+-Na + 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 CaZ+-loaded clinoptilolite, the cation-exchange capacity is substantially the same over the full range of loading by Ca > and Na +. Ca 2+ replaces Na + with decreasing selectivity as Ca > loading increases to about 80% at 30~ (95% at 63~ above which the selectivity reverses. The standard free energy of replacement of two Na + ions by one Ca > ion in 0.05 M solution is -1.2 + 0.2 kcal/mole at 63~ and -0.3 to -0.8 kcal/mole at 30~

Uranium removal from groundwater by natural clinoptilolite zeolite: Effects of pH and initial feed concentration

“…The data matches well with that of Na-Clinoptilolite (sodium form of clinoptilolite), which has the empirical chemical formula (Na, K, Ca) 2 -3(Si,Al) 18 …”

Research and Development Concerning Coalbed Natural Gas

“…The remaining exchangeable Na + in the WY-zeolite is strongly adsorbed and hard to replace with Ca 2+ . These findings were comparable with a previous study reported by Hulbert (1987). Hulbert (1987) investigated Na + , Ca 2+ , and NH 4 + exchange on zeolite materials collected from an outcrop of blue-green tuff in the Fort LaClede deposit, Sweetwater County, WY and found that Ca 2+ replaces Na + with decreasing selectivity as Ca 2+ loading increases to about 80% at 30ºC and that the Fort LaClede clinoptilolite at 30ºC has a moderate selectivity for Ca 2+ over Na + at < 80% Ca 2+ loading.…”

“…The WY-zeolite sample consisted of approximately 90% clinoptilolite with a minor amount of heulandite. A previous scanning electron microscopy (SEM) study by Hulbert (1987) found that our WY-zeolite deposit sample consisted of clinoptilolite crystals typically smaller than 10 m in diameter, grading into sub-micrometer size grains.…”

Modeling fluid-rock interaction at Yucca Mountain, Nevada; A progress report, April 15, 1992

“…Free energies of cation exchange at 25°C-Binary cation-exchange isotherms have been experimentally determined for various clinoptilolites at temperatures ranging from ambient to 75°C (Ames, 1964a(Ames, , 1964bBarrer et al, 1967;Frysinger, 1962;Howery and Thomas, 1965;Hulbert, 1987). The free energies of exchange derived from isotherms measured at 25 and 30°C for clinoptilolites from Washington, Oregon, and California are similar.…”