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Ion exchange equilibrium and structural changes in clinoptilolite irradiated with β- and γ-radiation: Monovalent cations

Christidis Georgios, Daniel Moraetis , Vassilis Perdikatsis

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URIhttp://purl.tuc.gr/dl/dias/3A1CDB38-D940-4433-923A-C1A4D150BB4B-
Identifierhttps://doi.org/10.2138/am.2007.2545-
Languageen-
Extent17 pagesen
TitleIon exchange equilibrium and structural changes in clinoptilolite irradiated with β- and γ-radiation: Monovalent cationsen
CreatorChristidis Georgiosen
CreatorΧρηστιδης Γεωργιοςel
CreatorDaniel Moraetis en
CreatorVassilis Perdikatsisen
Content SummaryThermodynamic calculations of ion-exchange reactions were applied for clinoptilolite in a natural state and after irradiation with three doses of β-radiation (1012, 1015, 3 × 1016 e/cm2) and γ-radiation (70 Mrad). Samples were equilibrated with binary systems of K+ ↔ Na+ and Cs+ ↔ Na+ at 25° and a total normality of 0.025 N. Selectivity for K was not affected after β-radiation with doses of 1012 and 1015 e/cm2 (ΔG° = –6.37 kJ/equiv, lnKα = 2.58 for the original clinoptilolite), whereas it increased considerably after 70 Mrad of γ-radiation (ΔG° = –7.88 kJ/equiv, lnKα = 3.18). Selectivity for Cs+ increased for the clinoptilolite irradiated with β-radiation (1012, 1015, 3 × 1016 e/cm2) and γ-radiation (70 Mrad). ΔG° and lnKα for original sample and Cs+ ↔ Na+ were –7.33 kJ/equiv and 2.96, respectively. Irradiated samples with β-radiation 1012, 1015, 3 × 1016 e/cm2 and 70 Mrad γ-radiation yielded ΔG° and lnKα –7.41, –8.83, –8.60, –8.25 kJ/equiv and 2.99, 3.57, 3.47, 3.33 for Cs+ ↔ Na+, respectively. Remarkable amorphization of clinoptilolite was observed after exposure at the highest dose of β-radiation (3 × 1016 e/cm2) with a concomitant decrease in cation-exchange capacity (CEC). Crystallographic parameters and especially exchangeable cation site coordinates were refi ned for all samples with the Rietveld method. Cesium-saturated samples exhibited changes in the cation sites Cs2 and Cs3, which are next to clinoptilolite channel walls with lower Al3+ for Si4+ substitution. The observed changes include a shift in cation sites Cs2 and Cs3 toward channel walls and occupancy decrease in site Cs2.el
Type of ItemPeer-Reviewed Journal Publicationen
Type of ItemΔημοσίευση σε Περιοδικό με Κριτέςel
Licensehttp://creativecommons.org/licenses/by/4.0/en
Date of Item2015-10-01-
Date of Publication2007-
Bibliographic CitationD. Moraetis , G.E. Christidis ,V. Perdikatsis ," Ion exchange equilibrium and structural changes in clinoptilolite irradiated with - and -radiation: Monovalent cations ",Am. Min. ,vol. 92 , no. 10 , pp.1714–1730 ,2007.doi :10.2138/am.2007.2545en

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