Partitioning of lithium between smectite and solution: An experimental approach
| Type | : | ACL |
|---|---|---|
| Nature | : | Production scientifique |
| Au bénéfice du Laboratoire | : | Non |
| Statut de publication | : | Publié |
| Année de publication | : | 2012 |
| Auteurs (6) | : | DECARREAU Alain VIGIER Nathalie PALKOVA Helena PETIT Sabine VIEILLARD Philippe FONTAINE C |
| Revue scientifique | : | Geochimica et Cosmochimica Acta |
| Volume | : | 85 |
| Fascicule | : | |
| Pages | : | 314-325 |
| DOI | : | 10.1016/j.gca.2012.02.018 |
| URL | : | <go to isi>://wos:000303107200019 |
| Abstract | : | Lithium is an element currently used as a tracer of water-rock interactions in continental and oceanic systems. Li is essentially concentrated in clays, and most often associated with Mg. However, there are to date few data on the partitioning of Li between Mg-clays and water that are required for developing appropriate weathering models. In this study, Mg-Li smectites (hectorites) were synthesized at 70, 90 and 150 degrees C, during periods ranging from 1 day to 4 months, and from solutions with various Li contents (typically from 2 to 190 mg/L). Pure hectorite fractions collected at the end of the syntheses were successively saturated three times with 1 N CaCl2 in order to completely eliminate exchangeable and adsorbed Li and Mg. The results show that the structural (octahedral) Li content of hectorites increases with Li concentration in solution, with temperature and with synthesis duration. A steady-state is reached after 4 weeks at 150 degrees C and after 2 months at 70 and 90 degrees C. Calculated partition coefficients, expressed either as D-Li = [Li(clay)]/[Li(aq)] (ppm/ppm) or as D'(Li/Mg) = (Li/Mg)(clay)/(Li/Mg) (solution) (ppm/ppm), increase with the synthesis temperature which is consistent with a true Li-Mg substitution within the clay lattice. DLi also increases when the Li concentration in solution decreases, and reaches 22 at 150 degrees C (using a 1.5 mg/L Li solution). A general expression for D-Li can be established: logD(Li) = -1319/T-(K) + 5.5 ([Li(aq)])(-0.0806). The main conclusion is that neoformed smectites which crystallize during water-rock interactions can be efficient Li sinks in the external geochemical cycle. Quantitative applications to several natural systems are assessed. (C) 2012 Elsevier Ltd. All rights reserved. |
| Mots-clés | : | - |
| Commentaire | : | Times Cited: 5 5 |
| Tags | : | - |
| Fichier attaché | : | - |
| Citation | : |
Decarreau A, Vigier N, Palkova H, Petit S, Vieillard P, Fontaine C (2012) Partitioning of lithium between smectite and solution: An experimental approach. Geochim Cosmochim Ac 85: 314-325 | doi: 10.1016/j.gca.2012.02.018
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