Actinide (III) solubility in WIPP Brine: data summary and recommendations

Borkowski, Marian; Lucchini, Jean-François; Richmann, Michael K.; Reed, Donald T.

doi:10.2172/966984

Cited by 11 publications

(22 citation statements)

References 33 publications

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“…The borate complexation effect in WIPP brine was only recently demonstrated on neodymium(III) [19,31]. Neodymium-tetraborate stability constants were experimentally determined in different NaCl ionic strength solutions and correlated well with the stability constants available in the literature [31] for others metals.…”

Section: Tetraborate Complexationmentioning

confidence: 67%

“…This dependence is valid for I > 0.5 M. For very low ionic strength solutions (I ∼ 0 M), the correction factor K is close to zero, so pC H + ∼ pH. The correction factors K were equal to 1.23 ± 0.01 for GWB and 0.94 ± 0.02 for ERDA-6 brine [19].…”

Section: Pc H + Measurementsmentioning

confidence: 72%

“…At 7 ≤ pC H + ≤ 9.2, where steady-state concentrations were established, the solubility of uranium(VI) in carbonate-free GWB was approximately 2 × 10 −6 M (between 8 × 10 −7 M and 5× 10 −6 M). The slight increase in the middle of this pC H + range (∼ 8.1) was not significant, but might reflect some borate complexation [19].…”

Section: Evolution Of U(vi) Concentration In Gwb and Erda-6 Brine Witmentioning

confidence: 82%

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Uranium(VI) solubility in carbonate-free WIPP brine

Lucchini¹,

Borkowski²,

Richmann³

et al. 2013

Radiochimica Acta

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The solubility of uranium(VI) was determined in WIPP-relevant brines as a function of pCH+ and ionic strength, in the absence of carbonate. Carbonate concentration was below 2 × 105 M, measured using the gas chromatography method. In the absence of carbonate, the uranium(VI) solubilities were about × 106 M in GWB at pCH+ ≥7 and about × 108– × 107 M in ERDA-6 brine at pCH+ ≥8. Solubility of uranium(VI) was also measured in NaCl media at the same levels as in ERDA-6 brine. The data established a uranium solubility that was 10–100 times lower than published results from Diaz-Arocas and Grambow [13], and they are in good agreement with modeling results and other literature data [11,12]. In the absence of carbonate, hydrolysis was the main complexation and precipitation mechanisms for uranium(VI) solubility at high ionic strength and pC H+ ≥7. However, the effect of borate complexation was noticeable at pCH+ ∼8–9.

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Section: Tetraborate Complexationmentioning

confidence: 67%

Section: Pc H + Measurementsmentioning

confidence: 72%

Section: Evolution Of U(vi) Concentration In Gwb and Erda-6 Brine Witmentioning

confidence: 82%

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Uranium(VI) solubility in carbonate-free WIPP brine

Lucchini¹,

Borkowski²,

Richmann³

et al. 2013

Radiochimica Acta

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“…The effect of the high ionic strength of the two simulated WIPP brines was taken into consideration in the determination of reliable hydrogen ion concentrations, using the following equation based on a modified Gran titration method [7]: pC H+ = pH obs + K, where pC H+ is the negative logarithm of the hydrogen ion concentration in molarity (mol/L or M) units, pH obs the measured/observed pH and K an experimentally determined constant. The correction factor K was found to be (0.94 0.02) for ERDA-6 and (1.23 0.01) for GWB [8]. The level of carbonate in the experiments was maintained by the addition of a small volume of an appropriate intermediate carbonate solution to achieve the desired concentration of carbonate in solution: 2 10 -4 M or 2 10 -3 M. The intermediate carbonate solution was prepared by dissolving a known amount of sodium carbonate in a determined volume of brine.…”

Section: +mentioning

confidence: 99%

“…These data indicated a possible effect of a ligand present in higher amounts in GWB than in ERDA-6, and an effect of the difference in ionic strength between the two brines. Based on our previous investigation of neodymium solubility [8], we postulated that borate may play a role in defining the uranium (VI) solubility in this pC H+ region (7.5 ≤ pC H+ ≤ 8). Three carbonate-free ERDA-6 solutions at an initial pC H+ of 8.1, 9.6 and 10.5 were saturated with a sodium tetraborate solid, reaching a total concentration of ~ 5×10 -2 M tetraborate in solution [9].…”

Section: First Regionmentioning

confidence: 99%

Influence of Carbonate on Uranium Solubility in the WIPP

Lucchini

Ballard

Khaing³

2012

MRS Proc.

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In the performance assessment (PA) for the Waste Isolation Pilot Plant (WIPP), the solubility of uranium (VI) was conservatively set at 10-3 M for all expected WIPP conditions, including the potential and likely effects of carbonate complexation [1]. Under WIPP-relevant conditions, long-term experiments were performed to establish the uranium (VI) solubility limits in WIPP-simulated brine over a broad range of pCH+ values [7.5-12.5] and to evaluate the contribution of carbonate complexation and hydrolysis to uranium (VI) speciation. Data obtained in carbonate-free ERDA-6 brine, a simulated WIPP brine, were reported earlier [2]. In the absence of carbonate, uranium solubility approached 10-7 M at the expected pCH+ in the WIPP (~ 9.5). In the presence of a significant amount of carbonate (millimole levels), recent experimental results showed that uranium (VI) concentrations will not exceed 10-4M. This measured solubility limit is an order of magnitude lower than the uranium solubility value currently used in the WIPP PA [3]. A small effect of borate complexation was found in the pCH+ range [7.5-10]. At pCH+ ≥ 10, hydrolysis overwhelmed carbonate effects, and no amphoteric effect was observed.

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Impact of Haloarchaea on Speciation of Uranium—A Multispectroscopic Approach

Bader

Roßberg

Steudtner

et al. 2018

Environ. Sci. Technol.

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Haloarchaea represent a predominant part of the microbial community in rock salt, which can serve as host rock for the disposal of high level radioactive waste. However, knowledge is missing about how Haloarchaea interact with radionuclides. Here, we used a combination of spectroscopic and microscopic methods to study the interactions of an extremely halophilic archaeon with uranium, one of the major radionuclides in high level radioactive waste, on a molecular level. The obtained results show that Halobacterium noricense DSM 15987 influences uranium speciation as a function of uranium concentration and incubation time. X-ray absorption spectroscopy reveals the formation of U(VI) phosphate minerals, such as meta-autunite, as the major species at a lower uranium concentration of 30 μM, while U(VI) is mostly associated with carboxylate groups of the cell wall and extracellular polymeric substances at a higher uranium concentration of 85 μM. For the first time, we identified uranium biomineralization in the presence of Halobacterium noricense DSM 15987 cells. These findings highlight the potential importance of Archaea in geochemical cycling of uranium and their role in biomineralization in hypersaline environments, offering new insights into the microbe-actinide interactions in highly saline conditions relevant to the disposal of high-level radioactive waste as well as bioremediation.

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Actinide (III) solubility in WIPP Brine: data summary and recommendations

Cited by 11 publications

References 33 publications

Uranium(VI) solubility in carbonate-free WIPP brine

Uranium(VI) solubility in carbonate-free WIPP brine

Influence of Carbonate on Uranium Solubility in the WIPP

Impact of Haloarchaea on Speciation of Uranium—A Multispectroscopic Approach

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