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Time-dependent sorption of Cd2+ on CaX zeolite : experimental observations and model predictions.

Ahmed, Imad A. M. and Young, Scott D. and Crout, Neil M. J. (2006) Time-dependent sorption of Cd2+ on CaX zeolite : experimental observations and model predictions. Geochimica and Cosmochimica Acta, 70 (19). pp. 4850-4861. ISSN 0016-7037

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Abstract

The effect of prolonged contact time (up to 130 days) on the immobilization of Cd by sorption to calcium exchanged zeolite-X (CaX), under environmentally relevant conditions, was studied using both isotopic exchange and extended X-ray absorption fine structure spectroscopy (EXAFS). Sorption and isotopic exchange measurements revealed time-dependent Cd sorption and indicated the movement of Cd2+ ions into less accessible sites due to ageing. EXAFS suggested progressive fixation of Cd in the double six-ring (D6R) unit of the CaX structure. Proportional allocation of the apparent Cd–Si bond distance to two ‘end-members’, across all contact times, indicated that the bond distance for labile Cd was 3.41 Å and for non-labile (or fixed) Cd was 3.47 Å.

Item Type: Article
Journal or Publication Title: Geochimica and Cosmochimica Acta
Uncontrolled Keywords: Zeolite ; model prediction ; Speciation ; Free ion activity ; chabazite ; intra-particle diffusion ; kinetic model ; diffusion model
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 33833
Deposited By: Dr Imad Ahmed
Deposited On: 20 Jul 2010 13:20
Refereed?: Yes
Published?: Published
Last Modified: 09 Apr 2014 21:56
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/33833

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