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Technical University of Crete
Technical University of Crete
EN
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| URI | http://purl.tuc.gr/dl/dias/3A1CDB38-D940-4433-923A-C1A4D150BB4B | - |
| Identifier | https://doi.org/10.2138/am.2007.2545 | - |
| Language | en | - |
| Extent | 17 pages | en |
| Title | Ion exchange equilibrium and structural changes in clinoptilolite irradiated with β- and γ-radiation: Monovalent cations | en |
| Creator | Christidis Georgios | en |
| Creator | Χρηστιδης Γεωργιος | el |
| Creator | Daniel Moraetis | en |
| Creator | Vassilis Perdikatsis | en |
| Content Summary | Thermodynamic 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 Item | Peer-Reviewed Journal Publication | en |
| Type of Item | Δημοσίευση σε Περιοδικό με Κριτές | el |
| License | http://creativecommons.org/licenses/by/4.0/ | en |
| Date of Item | 2015-10-01 | - |
| Date of Publication | 2007 | - |
| Bibliographic Citation | D. 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.2007.2545 | en |
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