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Institutional Repository [SANDBOX]
Technical University of Crete
Technical University of Crete
EN
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EL
| URI: | http://purl.tuc.gr/dl/dias/F68D9AD2-21B3-430D-9374-734B0C70060B | ||
| Year | 2003 | ||
| Type of Item | Peer-Reviewed Journal Publication | ||
| License |
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| Bibliographic Citation | G.E. Christidisa, D. Moraetis, E. Keheyan, L. Akhalbedashvili , N. Kekelidze , R. Gevorkyan , H. Yeritsyan , H. Sargsy ,"Chemical and thermal modification of natural HEU-type zeolitic materials from Armenia, Georgia and Greece ",Ap. Clay Sc.,vol.24 ,no.1 ,pp.79-91 ,2003.doi :10.1016/S0169-1317(03)00150-9 https://doi.org/10.1016/S0169-1317(03)00150-9 | ||
| Appears in Collections |
Three HEU-type zeolites from Armenia, Georgia and Greece formed from alteration of volcanic glass were treatedwith dilute KOH and subsequently either reacted with 6N HCl or heated at 700 jC. The raw materials and the reactionproducts were examined with X-ray diffraction (XRD), infrared spectroscopy (FTIR) and N2 gas adsorption. The cationexchange capacity (CEC) of the zeolites was also determined. The Greek zeolite has thermal characteristics typical forheulandite I, while the Armenian and Georgian zeolites have characteristics typical for heulandite III (clinoptilolite). KOHtreatment increased slightly specific surface area (SSA) and microporosity due to dissolution of amorphous material. Acidtreatment increased significantly both specific surface area and microporosity, as determined by t-plots, and decreasedCEC. This is attributed to partial dissolution of both Si-tetrahedra and free linkages, which yielded secondary microporesand destroyed specific exchange sites of the HEU-type zeolites. Heating decreased both specific surface area andmicroporosity.
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