Please use this identifier to cite or link to this item: doi:10.22028/D291-38487
Volltext verfügbar? / Dokumentlieferung
Title: Building the bridge between U(VI) and Ca-bentonite : Influence of concentration, ionic strength, pH, clay composition and competing ions
Author(s): Brix, Kristina
Baur, Sandra
Haben, Aaron
Kautenburger, Ralf
Language: English
Title: Chemosphere
Volume: 285
Publisher/Platform: Elsevier
Year of Publication: 2021
DDC notations: 500 Science
Publikation type: Journal Article
Abstract: In the context of a high-level nuclear waste disposal, the retention of U(VI) on non-pre-treated Ca-bentonite as potential technical barrier is studied. The objective of this study is to reveal the retention behaviour of U(VI) under extreme geochemical conditions, such as hyperalkaline pH range as well as high salinity at the same time, and taking into account other relevant parameters. This should lead to a better understanding of necessary safety precautions for avoiding a release of U(VI) in the environment. Batch experiments were conducted to determine the influence of the initial U(VI) concentration, salinity, pH value, clay composition and the presence of other elements (Ca(II), I−, Cs(I), Eu(III)). After the sorption experiments, the remaining U(VI) concentration in solution was determined via mass spectrometry with inductively coupled plasma. U(VI) can be immobilised from 10% to 100% under all investigated conditions. Precipitation plays a role in the U(VI) retention but only at higher concentrations (≥10−5 mol L−1). The retention is reversible especially with decreasing pH (<10.5) as the aquo complex Ca2UO2(CO3)3(aq) is formed. Ca(II) strongly enhances the U(VI) adsorption onto Ca-bentonite in the hyperalkaline pH range, probably due to the formation of Ca(II)-bridges. The best retention could be observed on natural bentonite compared to pure montmorillonite and altered bentonite. From a waste cocktail containing important elements of the repository inventory (Cs(I), Eu(III), U(VI) and iodide), only Eu(III) as homologous element to trivalent actinoids competes with U(VI) for binding sites, especially at low metal concentrations, but also facilitates the precipitation at higher concentrations.
DOI of the first publication: 10.1016/j.chemosphere.2021.131445
URL of the first publication:
Link to this record: urn:nbn:de:bsz:291--ds-384877
Date of registration: 9-Dec-2022
Faculty: NT - Naturwissenschaftlich- Technische Fakultät
Department: NT - Chemie
Professorship: NT - Prof. Dr. Guido Kickelbick
Collections:SciDok - Der Wissenschaftsserver der Universität des Saarlandes

Files for this record:
There are no files associated with this item.

Items in SciDok are protected by copyright, with all rights reserved, unless otherwise indicated.