Thermodynamic description of Be(II) solubility and hydrolysis in acidic to hyperalkaline NaCl and KCl solutions

Çevirim-Papaioannou, Neşe; Gaona, Xavier; Böttle, M.; Bethune, Ezgi Yalçıntaş; Schild, Dieter; Adam, Christian; Sittel, Thomas; Altmaier, M.

doi:10.1016/j.apgeochem.2020.104601

Cited by 10 publications

(30 citation statements)

References 60 publications

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“…In the context of the EU-funded collaborative project "Cement-based materials, properties, evolution, barrier functions" (Cebama), this study aims at a quantitative description of the beryllium uptake by cement HCP in degradation stage I under a range of initial beryllium concentrations ([Be] 0 ) and solid-to-liquid ratios (S/L). The present work complements and further expands the experimental study by Çevirim-Papaioannou et al, which was dedicated to the uptake of beryllium by HCP in degradation stage II and C-S-H phases [13].…”

Section: Introductionsupporting

confidence: 82%

“…Sorption samples were prepared with 20 mL of ACW and the corresponding amount of HCP to attain 2 g•L −1 ≤ [S/L] ≤ 50 g•L −1 . Stock solutions with [BeSO 4 ] aq = 0.35-10 −3 M were used to obtain the targeted initial Be concentrations of 1 × 10 −6 M ≤ [Be] 0 ≤ 0.03 M. Experimental solubility data and thermodynamic models reported in Çevirim-Papaioannou et al (2020) [13] for α-Be(OH) 2 (cr) in NaCl-NaOH and KCl-KOH systems were considered for the definition of the initial beryllium concentrations in the sorption experiments (see also Section 3). Sorption kinetics were monitored for t ≤ 145 days.…”

Section: Sorption Experimentsmentioning

confidence: 99%

“…In aqueous systems, beryllium is only expected in the +II oxidation state. The solubility and hydrolysis of Be(II) have been extensively studied under acidic conditions [5][6][7][8][9][10], but the number of experimental studies is very limited in the alkaline to hyperalkaline conditions [5,[11][12][13]. The recent work by Çevirim-Papaioannou and co-workers represents the most systematic solubility study of Be(II) with a focus on the alkaline pH conditions of relevance for cementitious systems [13].…”

Section: Introductionmentioning

confidence: 99%

“…The solubility and hydrolysis of Be(II) have been extensively studied under acidic conditions [5][6][7][8][9][10], but the number of experimental studies is very limited in the alkaline to hyperalkaline conditions [5,[11][12][13]. The recent work by Çevirim-Papaioannou and co-workers represents the most systematic solubility study of Be(II) with a focus on the alkaline pH conditions of relevance for cementitious systems [13]. In combination with extensive solid phase characterization and 9 Be NMR, the authors provided comprehensive chemical, thermodynamic, and activity models for the system Be 2+ -Na + -K + -H + -Cl − -OH − -H 2 O(l).…”

Section: Introductionmentioning

confidence: 99%

“…− and Be(OH) 4 2− [13]. The same criteria was retained in the updated sorption database reported by Wieland in 2014 [19].…”

Section: Introductionmentioning

confidence: 99%

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Uptake of Be(II) by Cement in Degradation Stage I: Wet-Chemistry and Molecular Dynamics Studies

et al. 2021

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The uptake of beryllium by hardened cement paste (HCP, with CEM I 42,5 N BV/SR/LA type) in degradation stage I was investigated with a series of batch sorption experiments with 10−6 M ≤ [Be(II)]0 ≤ 10−2.5 M and 2 g·L−1 ≤ [S/L] ≤ 50 g·L−1. All experiments were performed under Ar atmosphere at T = (22 ± 2) °C. Solubility limits calculated for α-Be(OH)2(cr) in the conditions of the cement pore water were used to define the experimental window in the sorption experiments. Beryllium sorbs strongly on HCP under all of the investigated conditions, with log Rd ≈ 5.5 (Rd in Lkg−1). Sorption isotherms show a linear behavior with a slope of ≈ +1 (log [Be(II)]solid vs. log [Be(II)]aq) over four orders of magnitude (10−8 M ≤ [Be(II)]aq ≤ 10−4 M), which confirm that the uptake is controlled by sorption processes and that solubility phenomena do not play any role within the considered boundary conditions. The similar uptake observed for beryllium in calcium silicate hydrate (C-S-H) phases supports that the C-S-H phases are the main sink of Be(II) in cement. The strong uptake observed for Be(II) agrees with the findings reported for heavier metal ions, e.g., Zn(II), Eu(III), Am(III), or Th(IV). The exceptional sorption properties of beryllium can be partially explained by its small size, which result in a charge-to-size ratio (z/d) of the same order as Eu(III) or Am(III). Kinetic experiments confirm the slow uptake of Be(II), which is characterized by a two-step process. In analogy to other strongly sorbing metal ions such as Zn(II) or Th(IV), a fast surface complexation (t < 4 days) followed by a slower incorporation of Be(II) in the C-S-H structure (t ≥ 60 days) are proposed. The surface complexation was studied in detail with molecular dynamic simulations, and the most common surface species are identified and described. This work provides the first experimental evidence supporting the strong uptake of Be(II) by HCP in degradation stage I, further extending previous findings on C-S-H phases and HCP in degradation stage II. These results overcome previous conservative estimates assuming no or only a weak uptake in cementitious systems and represent a relevant contribution for the quantitative assessment on the retention/mobilization of beryllium in the context of nuclear waste disposal.

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Section: Introductionsupporting

confidence: 82%

Section: Sorption Experimentsmentioning

confidence: 99%