The thermodynamics and kinetics of uranophane dissolution in bicarbonate test solutions

Citation
I. Perez et al., The thermodynamics and kinetics of uranophane dissolution in bicarbonate test solutions, GEOCH COS A, 64(4), 2000, pp. 603-608
Citations number
16
Categorie Soggetti
Earth Sciences
Journal title
GEOCHIMICA ET COSMOCHIMICA ACTA
ISSN journal
00167037 → ACNP
Volume
64
Issue
4
Year of publication
2000
Pages
603 - 608
Database
ISI
SICI code
0016-7037(200002)64:4<603:TTAKOU>2.0.ZU;2-#
Abstract
The thermodynamic and kinetic properties of a synthetic uranophane (Ca(H3O) (2)(UO2)(2)(SiO4)(2). 3H(2)O) have been determined from dissolution experim ents in test solutions of different bicarbonate concentrations at 25 degree s C. The experiments were performed using batch and continuously stirred ta nk flow-through reactors. From the experimental data obtained with the batc h reactor the solubility constant for the reaction: Ca(H3O)(2)(UO2)(2)(SiO4 )(2). 3H(2)O + 6H(3)O(+) double left right arrow Ca+2 + 2UO(2)(+2) + 2H(4)S iO(4) + 11H(2)O was determined to be log K-s0(O) = 11.7 +/- 0.6 and the rar e equation for the dissolution process is log r(dissol) (mol s(-1) m(-2)) = -8.3 (+/-0.6) + 0.7 (+/-0.3) log [HCO3-]. By using the continuously stirre d tank flow-through reactor we obtained a rate equation in reasonably good agreement with that obtained in the batch reactor: log r(dissol) (mol s(-1) m(-2)) = -9.2 (+/-0.4) + 0.7 (+/-0.2) log [HCO3-]. Copyright (C) 2000 Else vier Science Ltd.