Cation Exchange Selectivity Coefficient Values on Smectite and Mixed‐Layer Illite/Smectite Minerals

Tournassat, Christophe; Gailhanou, Hélène; Crouzet, Catherine; Braibant, Gilles; Gautier, Anne; Gaucher, Éric C.

doi:10.2136/sssaj2008.0285

Cited by 81 publications

(55 citation statements)

References 51 publications

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“…The cation exchanger composition estimated in equivalent fraction with the model of Tournassat et al (2009a) amounted to 18, 56 and 23% for Na, Ca and Mg, respectively. A low content of K was not considered in the calculation.…”

Section: Methodsmentioning

confidence: 97%

Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study

Montavon

Guo

Tournassat

et al. 2009

Geochimica et Cosmochimica Acta

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. Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study. Geochimica et Cosmochimica Acta, Elsevier, 2009, 73 (24) AbstractThe aim of the present work was to quantify accessible porosities for iodide and for a water tracer (HTO) on water-saturated compacted clay samples (illite, montmorillonite and MX-80 bentonite) and to relate these macroscopic values to the forms of water in these porosities (surface/bulk water, external/internal water). Low field proton NMR was used to characterize and quantify the forms of water. This enabled the three different populations (structural OH, external surface and internal surface water) to be differentiated on hydrated clays by considering the difference in proton mobility. An accurate description of the water forms within the different populations did not appear possible when water molecules of these populations were in contact because of the occurrence of rapid exchange reactions. For this 2 reason, it was not possible to use the low resolution NMR method to quantify external surface and bulk water in fully water-saturated compacted clay media at room temperature. This latter information could however be estimated when analyzing the samples at -25°C. At this temperature, a distinction based on the difference in mobility could be made since surface water remained in a semi-liquid state whereas bulk water froze. In parallel, accessible porosities for anions and HTO were determined by an isotopic dilution method using capillaries to confine the materials. HTO was shown to probe the whole pore volume (i.e. the space made of surface and bulk water). When the surface water volume was mainly composed of interlayer water (case of montmorillonite and bentonite), iodide was shown to be located in the pore space made of bulk water. When the interlayer water was not present (case of illite), the results showed that iodide could access a small fraction of the surface water volume localized at the external surface of the clay particles.

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Section: Methodsmentioning

confidence: 97%

Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study

Montavon

Guo

Tournassat

et al. 2009

Geochimica et Cosmochimica Acta

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“…The model considers ion exchange on illite and smectite represented by the selectivity exchange coefficients on the two exchangers [42,43].…”

Section: Callovian-oxfordian Claystone Modelmentioning

confidence: 99%

“…The ion exchange composition on the claystone was initially equilibrated with the COx pore water shown in Table 4. The selectivity coefficients available in Table 9 were calculated using exchange models given by Tournassat et al [42,43]. The coefficients are based on the Gaines and Thomas convention [50,51].…”

Section: Ion Exchangementioning

confidence: 99%

Benchmarks for multicomponent reactive transport across a cement/clay interface

Marty¹,

Bildstein

Blanc³

et al. 2015

Comput Geosci

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International audienceThe use of the subsurface for CO2 storage, geothermal energy generation, and nuclear waste disposal will greatly increase the interaction between clay(stone) and concrete. The development of models describing the mineralogical transformations at this interface is complicated, because contrasting geochemical conditions (Eh, pH, solution composition, etc.) induce steep concentration gradients and a high mineral reactivity. Due to the complexity of the problem, analytical solutions are not available to verify code accuracy, rendering code intercomparisons as the most efficient method for assessing code capabilities and for building confidence in the used model. A benchmark problem was established for tackling this issue. We summarize three scenarios with increasing geochemical complexity in this paper. The processes considered in the simulations are diffusion-controlled transport in saturated media under isothermal conditions, cation exchange reactions, and both local equilibrium and kinetically controlled mineral dissolution-precipitation reactions. No update of the pore diffusion coefficient as a function of porosity changes was considered. Seven international teams participated in this benchmarking exercise. The reactive transport codes used (TOUGHREACT, PHREEQC, with two different ways of handling transport, CRUNCH, HYTEC, ORCHESTRA, MIN3P-THCm) gave very similar patterns in terms of predicted solute concentrations and mineral distributions. Some differences linked to the considered activity models were observed, but they do not bias the general system evolution. The benchmarking exercise thus demonstrates that a reactive transport modelling specification for long-term performance assessment can be consistently addressed by multiple simulators

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“…Analyses of cation exchange populations were performed on whole rock samples using the cobalt hexamine method (Rémy and Orsini, 1976;Ciesielski and Sterckeman, 1997) as previously described by Gaucher et al (2004Gaucher et al ( , 2006 and Tournassat et al (2007Tournassat et al ( , 2008Tournassat et al ( , 2009. Experimental tests showed that carbonate minerals and sulphate minerals (e.g.…”

Section: Determinations Of Cation Exchange Populations and Cation Excmentioning

confidence: 99%

A robust model for pore-water chemistry of clayrock

Gaucher

Tournassat

Pearson³

et al. 2009

Geochimica et Cosmochimica Acta

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157

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Cation Exchange Selectivity Coefficient Values on Smectite and Mixed‐Layer Illite/Smectite Minerals

Cited by 81 publications

References 51 publications

Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study

Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study

Benchmarks for multicomponent reactive transport across a cement/clay interface

A robust model for pore-water chemistry of clayrock

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