TIME-DEPENDENT SORPTION OF CD2+ ON CAX ZEOLITE: EXPERIMENTAL OBSERVATIONS AND MODEL PREDICTIONS
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dc.contributor.author | Ahmed I.A.M. | |
dc.contributor.author | Young S.D. | |
dc.contributor.author | Crout N.M.J. | |
dc.date.accessioned | 2024-09-03T09:56:19Z | |
dc.date.available | 2024-09-03T09:56:19Z | |
dc.date.issued | 2006 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=31309399 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2006, 70, 19, 4850-4861 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/44843 | |
dc.description.abstract | Sorption, fixation and desorption kinetics of Cd2+ on calcium-exchanged zeolite-X were studied using an isotopic dilution technique utilizing 109Cd. The technique provided reliable measurements of time-dependent fixation of Cd and was validated using chabazite, which demonstrated wholly reversible Cd2+ ion exchange. A first-order kinetic model was developed to describe the progressive transfer of Cd2+ to a less reactive form in X-zeolite, following initial sorption, and subsequent desorption of Cd subject to different initial contact times. The kinetic model differentiates between two 'pools' of sorbed Cd2+ on zeolite-X, designated labile and non-labile sorbed Cd in which the labile sorbed Cd is in immediate equilibrium with the free Cd2+ ion activity in solution. Additionally, an intra-particle diffusion model was developed and compared with the kinetic model to determine whether time-dependent Cd sorption is controlled by reaction kinetics or diffusion within zeolite particles. The kinetic model provided a much better fit to the experimental data (R2 = 0.987) than the diffusion model. The rate constants describing Cd dynamics in CaX zeolite gave a half-time for Cd desorption of ~77 d, for release to a 'zero-sink'. © 2006 Elsevier Inc. All rights reserved. | |
dc.title | TIME-DEPENDENT SORPTION OF CD2+ ON CAX ZEOLITE: EXPERIMENTAL OBSERVATIONS AND MODEL PREDICTIONS | |
dc.type | Статья | |
dc.identifier.doi | 10.1016/j.gca.2006.07.011 |
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