Ion Exchange on the Mineral Clinoptilolite

Howery, Darryl G.; Thomas, Henry C.

doi:10.1021/j100886a029

Cited by 62 publications

(18 citation statements)

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“…3 kcal/mole at 30~ and by Barrer et al (1967) ( -1 . 3 kcal/mole recalculated from their determination at 60~ to the 30~ value by use of the enthalpy value reported by Howery and Thomas (1965)). …”

Section: Sodium-ammonium Ion Competitionmentioning

confidence: 99%

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

Hulbert¹

1987

Clays and clay miner.

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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~

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Section: Sodium-ammonium Ion Competitionmentioning

confidence: 99%

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

Hulbert¹

1987

Clays and clay miner.

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“…The selectivity coefficient generally decreases with increasing saturation of the preferred cation on montmorillonite (Eliason, 1968;Gast, 1969;Lewis and Thomas, 1963) with the values varying as much as a factor of 3-5. As Howery and Thomas (1965) have pointed out, this variation may be explained on the basis of nonideal mixing and/or by a variation in the binding energies of the exchange sites, and it is difficult to resolve which factor is actually responsible.…”

Section: Entropies Of Exchangementioning

confidence: 99%

“…The thermodynamic equilibrium constant and surface phase activity coefficients may be related to the experimentally determined selectivity coefficient by equations (5-7) if appropriate standard states are used along with the GibbsDuhem equation (Gaines and Thomas, 1953;Howery and Thomas, 1965) In/~B A = f~ In Kcd,gB (5) lnfA=--2BlnKc+ fXoBlnK~d2B If the surface behaves as an ideal solid in that there are no significant interactions between ions on neighboring sites, and if all exchange sites are alike, the surface phase activity coefficients for equi-charge exchange have the constant value of unity and the selectivity coefficient is a constant value equal to the thermodynamic equilibrium constant for all surface compositions. In such ideal systems, the free energy of mixing, AG,/, is given by the relationship (Howery and Thomas, 1965) AG,fl:RT(X,~InkA+XBlnkB).…”

Section: Evaluation Of Thermodynamic Quantitiesmentioning

confidence: 99%

“…In such ideal systems, the free energy of mixing, AG,/, is given by the relationship (Howery and Thomas, 1965) AG,fl:RT(X,~InkA+XBlnkB).…”

Section: Evaluation Of Thermodynamic Quantitiesmentioning

confidence: 99%

“…In addition, if exchange isotherms are determined for two or more temperatures, the heat of mixing can be calculated from the temperature coefficients of fA and fB using the expression (Howery and Thomas, 1965) Finally, knowing AG,, x and AH,n x the excess entropy of mixing, AS,S, can be calculated from the relationship AG,,, x = AH,,, x-TAS,, x.…”

Section: =Rt(f(alnfa+f(blnfb) (13)mentioning

confidence: 99%

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Sodium-Lithium Exchange Equilibria on Vermiculite at 25° and 50°C

Gast¹

1971

Clays and clay miner.

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Abstract-Sodium-lithium exchange equilibria between dilute aqueous chloride solutions and 0.2-62/z Transvaal, South African vermiculite were studied at 25 ~ and 50~ using a dialysis technique. The K content of the vermiculite was reduced to < 1% of the exchange capacity of 2.14 me/g by exhaustive extraction using Na-tetraphenylboron. The thermodynamic equilibrium constants and in turn the standard free energies and heats of exchange were evaluated from the equilibrium selectivity coefficients at the two temperatures. The standard entropy of exchange, AS ~ was calculated according to the relationship AG ~ = AH ~ --TAS ~ Similar results were obtained for Na ~ Li and Li ~ Na exchange at 25~ thus confirming the reversibility of the reaction.Sodium preference increased with Na saturation of the vermiculite and equilibrium selectivity coefficients ranged from 6-0 to 22.0 at 25~ In comparison, selectivity coefficients for Na-Li exchange on montmorillonite ranged from 1.0 to 2.0 and became smaller with increasing Na saturation. The standard free energy and heat of exchange on vermiculite at 25~ were-1444 and-5525 cal mole -1, respectively, resulting in a AS ~ value of-13.7 e.u. This relatively large entropy change is probably due to differences in ion hydration in the solution and surface phases.

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Synthesis and Characterizations of High Crystallized Clinoptilolite by Structure Directing Agent Method and its Crystallization Kinetics

et al. 2021

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The clinoptilolites (CPs) with high purity were prepared via structure directing agent (SDA) method combining with hydrothermal method using silica sol as the silica source and aluminum hydroxide as the aluminum source. Their structural features were characterized by X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectra, thermal gravimetric (TG) analysis, scanning electron micrograph (SEM) images, 29 Si nuclear magnetic resonance (NMR) profiles. The effects of additive amount and aging time of used SDA, as well as synthetic parameters such as crystallization temperature and crystallization time on their structure and performance were emphasized. Particularly, the activation energies of their crystallization kinetics at different stages of induction period and growth period were calculated on the basis of Arrhenius equation. The results demonstrated that the obtained CPs presented the highest relative crystallinity when the additive amount of used SDA was 1 mL at aging periods of 2 d, otherwise, their relative crystallinity degree was low due to existences of a large number of heterocrystal impurities. Particularly, the apparent activation energy values for induction (E n) and growth (E g) profile were calculated by the Arrhenius equation. The E n value (86.46 kJ/mol) of induction period was much higher than that E g value (9.64 kJ/mol) of growth stage, suggesting that the induction period was the main controlling step during the synthetic CP. Finally, the synthetic CP was employed to preliminarily assess its performances for CH 4 /N 2 separation. These demonstrations provide a promising method for the synthesis of CPs.

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Ion Exchange on the Mineral Clinoptilolite

Cited by 62 publications

References 0 publications

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

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

Sodium-Lithium Exchange Equilibria on Vermiculite at 25° and 50°C

Synthesis and Characterizations of High Crystallized Clinoptilolite by Structure Directing Agent Method and its Crystallization Kinetics

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