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Ion exchange equilibrium and structural changes in clinoptilolite irradiated with beta - and gamma -radiation; Part II, Divalent cations

Daniel Moraetis, George E. Christidis and Vasilios Perdikatsis
Ion exchange equilibrium and structural changes in clinoptilolite irradiated with beta - and gamma -radiation; Part II, Divalent cations
European Journal of Mineralogy (August 2008) 20 (4): 603-620

Abstract

Thermodynamic calculations of ion exchange for divalent cations were made for clinoptilolite in natural state and after irradiation with three different doses of beta -radiation (10 (super 12) , 10 (super 15) and 3X10 (super 16) e/cm (super 2) ) and gamma -radiation (70 Mrad). The samples were equilibrated with binary systems of divalent cations, namely Sr (super 2+) <-->2Na (super +) , Ca (super 2+) <-->2Na (super +) and Mg (super 2+) <-->2Na (super +) at 25 degrees C and total solution normality of 0.025 N. The selectivity order Sr (super 2+) >Ca (super 2+) >Mg (super 2+) was observed in non-irradiated clinoptilolite. After irradiation with gamma -radiation the affinity of clinoptilolite for Sr (super 2+) increased and that for Mg (super 2+) decreased, whereas the affinity for Ca (super 2+) remained unchanged. Irradiation with beta -radiation influences selectivity order and clinoptilolite affinity decreases for Sr (super 2+) , whereas it increases for Ca (super 2+) . For the sample irradiated with maximum dose of beta -radiation the selectivity was almost identical for Ca (super 2+) and Sr (super 2+) . The crystallographic parameters and exchangeable cation site coordinates were refined for all samples with the Rietveld method. The structure refinement of Sr (super 2+) -saturated samples yielded changes both in exchangeable sites and site occupancy in channels A and B after irradiation with beta -and gamma -radiation. The cation sites Sr1 and Sr3 exhibit major changes both in site coordinates and site occupancy after irradiation with beta -radiation. In addition, irradiation with gamma -radiation yielded major changes in Sr1 occupancy, whereas coordinates changed only slightly. These structural modifications control the observed changes in thermodynamic parameters after irradiation.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 20
Serial Issue: 4
Title: Ion exchange equilibrium and structural changes in clinoptilolite irradiated with beta - and gamma -radiation; Part II, Divalent cations
Affiliation: Technical University of Crete, Department of Mineral Resources Engineering, Chania, Greece
Pages: 603-620
Published: 200808
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 60
Accession Number: 2008-114908
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200843
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