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http://hdl.handle.net/10773/19969
Title: | Cs+ ion exchange over lanthanide silicate Eu-AV-20: Experimental measurement and modelling |
Author: | Figueiredo, Bruno R. Ananias, Duarte Rocha, Joao Silva, Carlos Manuel |
Keywords: | MICROPOROUS TITANOSILICATE ETS-4 MAXWELL-STEFAN APPROACH ZIRCONIUM PHOSPHATE TITANIUM SILICATES CRYSTAL-STRUCTURES RADIOACTIVE-WASTE AQUEOUS-SOLUTION ACIDIC-SOLUTIONS ENERGY-TRANSFER WATER SOLUTIONS |
Issue Date: | 2015 |
Publisher: | ELSEVIER SCIENCE SA |
Abstract: | The ion exchange of Cs+ from aqueous solutions was studied using for the first time a microporous lanthanide silicate with photoluminescence properties, Eu-AV-20. It was prepared by hydrothermal synthesis, characterized by SEM, PLS, PXRD and ICP-MS, and several batch ion exchange experiments were performed to measure isotherm and removal curves. Additional curves were measured to evaluate the competition with Na+. The results evidenced the great selectivity of Eu-AV-20 towards Cs+ since cesium removal was slightly modified even for Na+/Cs+ concentrations ratio of 190. The emission photoluminescent spectra of native and Cs+-exchanged Eu-AV-20 were also determined for the first time, and significant modifications were detected, which discloses the potential of Eu-AV-20 for Cs+ sensing purposes. The Langmuir equation provided a good fit to the equilibrium data, with average error of 5.3%, and the Maxwell-Stefan based model adopted to represent the kinetic curves (i.e., concentration versus time) achieved a deviation of 19.0%. An analysis of variance confirmed that the model was statistically significant to represent the uptake curves. The Maxwell-Stefan based model comprises three parameters, namely, the diffusion coefficients associated to the interactions of Cs+ and Eu-AV-20, Na+/K+ and Eu-AV-20, and Cs+ and Na+/K+, whose fitted values were 2.706 x 10(-15), 5.713 x 10(-15) and 9.446 x 10(-12) m(2) s(-1). Such low values evidenced that the intraparticle mass transport mechanism is surface diffusion. This fact is ascribed to the small pores of the Eu-AV-20 crystal, 5.8 x 6.8 angstrom, because the counter ions never escape from the force field of the framework co-ions, mainly due to the strong and long range nature of the electrostatic interactions. (C) 2015 Elsevier B.V.,All rights reserved. |
Peer review: | yes |
URI: | http://hdl.handle.net/10773/19969 |
DOI: | 10.1016/j.cej.2015.01.048 |
ISSN: | 1385-8947 |
Publisher Version: | 10.1016/j.cej.2015.01.048 |
Appears in Collections: | CICECO - Artigos |
Files in This Item:
File | Description | Size | Format | |
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Cs+ ion exchange over lanthanide silicate Eu-AV-20 Experimental measurement and modelling_10.1016j.cej.2015.01.048.pdf | 1.96 MB | Adobe PDF |
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