Untersuchung von Ionenaustauschgleichgewichten an synthetischen Zeolithen des Typs A

Wolf, Friedrich; Fürtig, H.

doi:10.1007/bf01500336

Cited by 13 publications

(4 citation statements)

References 8 publications

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“…This indicates that affinity of zeolite A to Pb 2ϩ ions is considerably higher than the affinity to Zn 2ϩ ions under similar conditions (N ϭ 0.1 geq dm Ϫ3 , T ϭ 20-60°C). The increase in equilibrium zinc content with increasing exchange temperature is a consequence of the effects appearing at higher temperatures (47,48). 1a) ions from solutions and Na ϩ ions from zeolite A, the exchange temperature does not affect the equilibrium of the exchange process between Pb 2ϩ ions from solutions and Na ϩ ions from zeolite A (see Fig.…”

Section: Resultsmentioning

confidence: 97%

Removal of Heavy–Metal Ions from Solutions by Means of Zeolites. II. Thermodynamics of the Exchange Processes Between Zinc and Lead Ions from Solutions and Sodium Ions from Zeolite A

Biškup¹,

Subotić²

2000

Separation Science and Technology

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Relationships between the corrected selectivity coefficient, K C (Me) (Me ϭ Zn, Pb), and fraction of the exchanged Me 2ϩ ions in zeolite A, ƒ Me,Z , were determined from the corresponding exchange isotherms. The exchange isotherms were obtained by measuring the equilibrium concentrations of sodium and Me 2ϩ ions in both the solid and the liquid phase at constant total-ion concentrations and different temperatures in the range from 20°C to 60°C. Thermodynamic equilibrium constants, K a (Me), calculated from the corresponding Kielland's plots (lnK C (Me) vs. ƒ Me,Z plots) were used for the calculation of the appropriate values of standard free energy, ⌬G°(Me), standard enthalpy, ⌬H°(Me), and standard entropy, ⌬S°(Me).

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Section: Resultsmentioning

confidence: 97%

Removal of Heavy–Metal Ions from Solutions by Means of Zeolites. II. Thermodynamics of the Exchange Processes Between Zinc and Lead Ions from Solutions and Sodium Ions from Zeolite A

Biškup¹,

Subotić²

2000

Separation Science and Technology

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“…For divalent-divalent exchange reactions the thermodynamic equilibrium constant is given by K = (MliZ2+)(M2>82+) FWT oo (M1|S2+)(M2jZ2+) (12) where F22 -/m,//m2 and 22 -…”

Section: Discussionmentioning

confidence: 99%

“…Isotherms plus thermodynamic equilibrium constants have subsequently been reported by Barrer et al (2,3), Ames (4), Sherry et al (5,6), Gal et al (7-9), and Rees (10). Concurrently, there have been numerous less quantitative studies reported by Barrer and Meier (11), Wolf et al (12)(13)(14), Zhdanov et al (25), Dubinin et al (16), and Seff et al (17)(18)(19)(20)(21)(22)(23)(24).…”

Section: Introductionmentioning

confidence: 99%

Divalent and trivalent ion exchange with zeolite A

Wiers¹,

Grosse²,

Cilley³

1982

Environ. Sci. Technol.

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~~The ion-exchange isotherm for Ca2+ exchange with sodium zeolite A was determined at 25 OC by using a novel solid uptake analytical scheme and a Langmuir adsorption model, resulting in an improved value for the thermodynamic equilibrium constant. Ion-exchange isotherms and approximate thermodynamic equilibrium constants were also determined for calcium zeolite A exchange with Pb2+, Cd2+, and Cu2+. Pb2+ and Cd2+ exchanges were found to be reversible, whereas Cu2+ exchange was not, probably due to Cu(OH),(s) precipitation upon or within the zeolite.Ion exchange was attempted but found to be irreversible with C$+, Hg2+, Fe3+, and A13+. Except for Cr3+, these ions caused zeolite A structure degradation, probably through extensive proton exchange. Cr3+ exchanged partially and then formed a precipitate. Data obtained in this work provide an improved understanding of the possible environmental water effects of zeolite A.

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“…A precursor of ZnO/zeolite A was synthesized by stirring a zeolite A (Degussa, Wessalith P) suspension in water with ZnCl2 in order to exchange Na + for Zn + ions [15]. Subsequent heating (600 °C, 4 hours) of the ion exchanged zeolite led directly to the formation of the small ZnO clusters within the zeolite cages as indicated by the changes of the powder X-ray diffraction patterns.…”

Section: Methodsmentioning

confidence: 99%

Optical properties of zinc oxide clusters encapsulated in a zeolite host

Türk

Sabin

Vogler

1992

Materials Research Bulletin

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The optical properties of nanometer-sized semiconductor materials are of interest in areas such as photocatalysis and non-linear optics. Ultrasmail zinc oxide particles encapsulated in a porous zeolite (A) host were characterized by powder X-ray diffraction, reflectance, and luminescence spectra. Compared to bulk ZnO the particles show pronounced blue shifts of the reflectance as well as the luminescence bands owing to the quantum size effect.

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Untersuchung von Ionenaustauschgleichgewichten an synthetischen Zeolithen des Typs A

Cited by 13 publications

References 8 publications

Removal of Heavy–Metal Ions from Solutions by Means of Zeolites. II. Thermodynamics of the Exchange Processes Between Zinc and Lead Ions from Solutions and Sodium Ions from Zeolite A

Removal of Heavy–Metal Ions from Solutions by Means of Zeolites. II. Thermodynamics of the Exchange Processes Between Zinc and Lead Ions from Solutions and Sodium Ions from Zeolite A

Divalent and trivalent ion exchange with zeolite A

Optical properties of zinc oxide clusters encapsulated in a zeolite host

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