Temperature effect on the acid–base behaviour of Na-montmorillonite

Duc, Myriam; Carteret, Cédric; Thomas, Fabien; Gaboriaud, Fabien

doi:10.1016/j.jcis.2008.08.050

Cited by 14 publications

(10 citation statements)

References 23 publications

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“…The ∆ r H θ m of surface reactions responsible for the acid-base chemistry of the Na-bentonite were also assumed to be 0. This assumption is reasonable according to the work by Duc et al [17], which indicated that the protonation and deprotonation reactions on edge sites of montmorillonite are not significantly temperature-dependent. Moreover, according to the negligible temperature effect upon U(VI) sorption at low pH (Fig.…”

Section: Effect Of Temperature On U(vi) Sorption Onto Na-bentonitesupporting

confidence: 53%

“…Considering the temporal and spatial variation of temperature in the near field of deep geological repository for high-level radioactive waste, ∆ r H θ m of surface reactions involving radionuclide sorption on backfilling materials (e.g. bentonite) are necessary for nuclear waste management [15][16][17]. In this study, U(VI) sorption curves vs. pH on the Na-bentonite measured at C 0 U(VI) = 8.02 × 10 −5 mol/L, I = 0.1 mol/L NaCl, m/V = 1 g/L and three temperatures (298 ± 2, 333 ± 2 and 353 ± 2 K) were collected to evaluate the ∆ r H θ m of surface reactions in the proposed model.…”

Section: Effect Of Temperature On U(vi) Sorption Onto Na-bentonitementioning

confidence: 99%

“…It is well known that the near-field temperature in deep geological repository for high-level radioactive waste may be higher than the ambient temperature and vary with time because of radionuclide decay [15][16][17]. However, most sorption data reported up to date were collected at ambient temperature and studies on temperature effect are still lacking [15].…”

Section: Introductionmentioning

confidence: 99%

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Temperature effect on U(VI) sorption onto Na-bentonite

et al. 2010

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International audienceU(VI) sorption on a purified Na-bentonite was investigated from 298±2 to 353±2 K by using a batch experimental method as a function of pH, U(VI) concentration, carbonate concentration and solid-to-liquid ratio (m/V). The data at 298±2 K could be well described by a surface complexation model (SCM) with a complex located on layer sites (X2UO2) and three complexes located on edge sites (≡SOUO2+, ≡SO(UO2)3(OH)5, and ≡SO(UO2)3(OH)72-). The intrinsic equilibrium constants (Kint) of the surface reactions at 333±2 K and 353±2 K were obtained by fitting U(VI) sorption curves versus pH on the Na-bentonite. The model enables U(VI) sorption in the presence of carbonate ( =10-3.58 atm) to be described without considering any ternary surface complexes involving carbonate, except for underestimation around pH 7 (6 < pH < 7.5). The standard enthalpy changes ( ) of the surface reactions were evaluated from the Kint values obtained at three temperatures (298±2, 333±2 and 353±2 K) via the van't Hoff equation. The proposed SCM and of the surface reactions enable U(VI) sorption on the Na-bentonite at other temperatures to be predicted

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Section: Effect Of Temperature On U(vi) Sorption Onto Na-bentonitesupporting

confidence: 53%

Section: Effect Of Temperature On U(vi) Sorption Onto Na-bentonitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temperature effect on U(VI) sorption onto Na-bentonite

et al. 2010

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“…Huertas et al (1998) showed that after an equilibration time of 24 h, dissolved Al 3+ affects the titration curves of kaolinite significantly. At equilibration times of 24 h at 25ºC, measurable concentrations of Al and Fe were found in Nasmectites by Duc et al (2008). In contrast, Turner et al (1996) found dissolved Al to be below the detection limit in Na-smectites, but observed exchangeable Al 3+ in amounts high enough to complicate quantitative analysis of the proton adsorption.…”

Section: Low Pk Rangementioning

confidence: 97%

The acidity of surface groups of dioctahedral smectites

Kaufhold¹,

Stanjek²,

Penner³

et al. 2011

Clay miner.

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Suspensions of thirty six bentonites were equilibrated for 24 h and then adjusted to pH 3. After an hour, pH titrations up to pH 12 at varying ionic strengths were performed within 4.5 h. The titration data were recalculated into proton affinity distributions (PAD) using the condensed approximation. In spite of widely varying chemical compositions, all bentonites showed a protonation reaction between pK 4 and 5, which could be assigned to aluminol groups at the edge surfaces of the smectites. The average pK is 4.73±80.31. A second prominent peak in the PAD at pK = 10.43±80.13 could be assigned to exchangeable Mg2+ in the interlayer space. The possibility to constrain both pK values at a fixed average value will decrease the number of parameters in surface complexation modelling and thus enhance its convergence.

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“…This rate dependence can be described by: R (mol m − 2 s − 1 ) = 10 − 12.30 a 0.40 H + + 10 − 14.37 + 10 − 13.05 a 0.27 OH − . Enhanced release of Al from Na + -montmorillonite was also observed in solution with pH <4.00 or >11.0 (Duc et al 2008;Rozalén et al 2008Rozalén et al , 2009.…”

Section: Resultsmentioning

confidence: 94%

Salinity and pH affect Na⁺-montmorillonite dissolution and amino acid adsorption: a prebiotic chemistry study

Farias

Tadayozzi

Carneiro

et al. 2014

International Journal of Astrobiology

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The adsorption of amino acids onto minerals in prebiotic seas may have played an important role for their protection against hydrolysis and formation of polymers. In this study, we show that the adsorption of the prebiotic amino acids, glycine (Gly), α-alanine (α-Ala) and β-alanine (β-Ala), onto Na+-montmorillonite was dependent on salinity and pH. Specifically, adsorption decreased from 58.3–88.8 to 0–48.9% when salinity was increased from 10 to 100–150% of modern seawater. This result suggests reduced amino acid adsorption onto minerals in prebiotic seas, which may have been even more saline than the tested conditions. Amino acids also formed complexes with metals in seawater, affecting metal adsorption onto Na+-montmorillonite, and amino acid adsorption was enhanced when added before Na+-montmorillonite was exposed to high saline solutions. Also, the dissolution of Na+-montmorillonite was reduced in the presence of amino acids, with β-Ala being the most effective. Thus, prebiotic chemistry experiments should also consider the integrity of minerals in addition to their adsorption capacity.

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Temperature effect on the acid–base behaviour of Na-montmorillonite

Cited by 14 publications

References 23 publications

Temperature effect on U(VI) sorption onto Na-bentonite

Temperature effect on U(VI) sorption onto Na-bentonite

The acidity of surface groups of dioctahedral smectites

Salinity and pH affect Na⁺-montmorillonite dissolution and amino acid adsorption: a prebiotic chemistry study

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Temperature effect on the acid–base behaviour of Na-montmorillonite

Cited by 14 publications

References 23 publications

Temperature effect on U(VI) sorption onto Na-bentonite

Temperature effect on U(VI) sorption onto Na-bentonite

The acidity of surface groups of dioctahedral smectites

Salinity and pH affect Na+-montmorillonite dissolution and amino acid adsorption: a prebiotic chemistry study

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Product

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Salinity and pH affect Na⁺-montmorillonite dissolution and amino acid adsorption: a prebiotic chemistry study