Retardation of Technetium and Iodine by Antimony- and Mercury-Containing Minerals

Zhuang, Η. E.; Zheng, Jiaxin; Xia, Di; Zhu, Zhigang

doi:10.1524/ract.1995.68.4.245

Cited by 18 publications

(13 citation statements)

References 5 publications

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“…However, under reducing conditions, and in the absence of complexing agents, the tetravalent Tc(IV) ion dominates (Francis et al 2002). In this oxidation state, 99 Tc is relatively immobile and can form highly insoluble minerals like TcO 2 and strong complexes on Al, Fe, and Sb oxides as well as on clays (Lieser and Bauscher 1987;Meyer et al 1991;Haines et al 1987;Zhaung et al 1995). Such changes can be mediated by abiotic and/or biotic processes.…”

Section: Degradation/transformationmentioning

confidence: 99%

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Vadose Zone Contaminant Fate and Transport Analysis for the 216-B-26 Trench

Ward¹,

Gee²,

Zhang³

et al. 2004

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U. Owing to the potential risk, remediation is being accelerated at this site. Developing an effective remediation plan and evaluating remedial options for the site requires a detailed analysis of fate and transport for this site and such an analysis must rely on numerical modeling. The purpose of this study was to develop a conceptual model for contaminant fate and transport at the 216-B-26 Trench site to allow interpretation of the current contaminant distributions and to support identification, development, and evaluation of remediation alternatives.In developing the conceptual model, the presence of large concentrations of 99 Tc high above the water table implicated stratigraphy in the control of the downward migration. The resulting conceptual model therefore included 1) small-scale stratigraphy and changes in physical and chemical properties, 2) tilted layers to accommodate the natural slope to the formation, and 3) lateral spreading along multiple strata with contrasting physical properties. Flow and transport properties were derived using physically based pedotransfer functions that were coupled with high-resolution neutron moisture logs taken on a vertical spacing of 0.076 m. Heterogeneity in the longitudinal and transverse horizontal directions was incorporated by using geostatistical methods to overlay the spatial correlation structure of flow variables from the well-characterized 299-E24-111 test site on to the simulation domain. Two approaches were used to compare no-action and capping remedial alternatives. The first approach, based on a simple analytical convolution solution to the convective-dispersive equation, assumed steady downward flow and allowed for spatially averaged or variable water content. This approach was combined with a soil screening protocol to calculate soil screening levels (Tables S1 and S2) and contaminant concentrations reaching hypothetical receptors down gradient of the site. In the second approach the STOMP simulator was used to predict contaminant transport through the vadose zone and into a 5-m thick confined aquifer during transient multidimensional flow.Both modeling approaches show that leachate concentrations reaching the water table would exceed the MCLs under the no-action alternatives with hypothetical recharge rates of 25 and 3.5 mm/yr. Soil screening levels were exceeded under the no-action alternatives and concentrations of mobile contaminants reaching hypothetical receptor wells consistently exceeded the MCLs (Tables S3 and S4). Owing to the large inventory of 99 Tc and NO 3 -, the high mobility of the two contaminants, and the long half life of 99 Tc, additional measures appear necessary to meet the appropriate soil screening levels. In this respect, on-site capping was evaluated simply by reducing surface recharge to mimic the design performance of hypothetical surface barriers. Both modeling approaches show capping to be an effective technology for remediating the site. Capping successful removed the threat to ground water through a reduction in mass flux ...

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Section: Degradation/transformationmentioning

confidence: 99%

“…In this oxidation state, 99 Tc is relatively immobile and can form highly insoluble minerals like TcO 2 , as well as strong complexes on Al, Fe, and Sb oxides as well as clays (Lieser and Bauscher 1987;Meyer et al 1991;Haines et al 1987;Zhaung et al 1995).…”

Section: Bulk Density and Distribution Coefficientmentioning

confidence: 99%

Vadose Zone Contaminant Fate and Transport Analysis for the 216-B-26 Trench

Ward¹,

Gee²,

Zhang³

et al. 2004

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“…These anionic species are of serious concem because their migration is poorly retarded by geological materials such as kaolinite, montmorillonite and granite [3][4][5]. Several researchers have focused on the sorption studies of anionic species on inorganic sorbents [6][7][8][9][10]. It has been suggested that technetium can be sorbed on minerals containing iron or sulfide by reducing TCO4 to TcOzCs) [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Several researchers have focused on the sorption studies of anionic species on inorganic sorbents [6][7][8][9][10]. It has been suggested that technetium can be sorbed on minerals containing iron or sulfide by reducing TCO4 to TcOzCs) [7][8][9]. In the iodine sorption studies, mercury-or sulfide-containing minerals show a high capacity for the retardation of [3,10].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Sorption Behavior of I^- and TcO^- ₄ on Mg/Al Layered Double Hydroxide

Chun

Rhee

et al. 1999

Radiochimica Acta

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Layered double hydroxide /1 / TcO^ / lon-exchange / Simultaneous sorption SummaryThe Sorption behavior of I" on calcined Mg/AI layered double hydroxide (LDH) was investigated. The batch sorption experiments were carried out in an inert atmosphere and at a constant temperature of 25 °C. Sorption is based on stepwise ionexchange equilibria involving the LDH hydroxide. The determined equilibrium constants of K^ and K2 are 7.4±1.0 and 0.2±0.4, respectively. The dominant reaction is the first ionexchange equilibrium, which is the replacement of one 0H~ ion of the LDH hydroxide by an T ion to form MgeAl2(OH)"(I)(s). The K, value for T sorption is 5 times higher than that for MOj (M = To, Re) sorption. An iodide ion is more selective for sorption on the calcined LDH. The sorption behavior of I" in the presence of TcOj was investigated. The batch sorption experiments were conducted by using I" and ReO^ as a TcOj Surrogate. The sorbed concentrations of 1" and ReOz in simultaneous sorption are similar to those in Single ion sorption. The I" and ReOj show an independent sorption behavior on calcined LDH when these anions are mixed. It means that Mg6Al2(0H),7(Re04) exists with Mg6Al2(OH),7(I) in the LDH unit.

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“…Tc attenuation performance of sulfide minerals is highly variable and appears to depend on a number of factors, such as the type of mineral, particle size, type of contacting solution, pH, ionic strength, and Eh (Balsley et al 1997, Fried et al 1978Lee and Bondietti 1983, Lieser and Bauscher 1988, Palmer and Meyer 1981, Strickert et al 1980Zhuang et al 1988, Zhuang et al 1995. It is generally recognized that the principal mechanisms of 99 Tc attenuation by sulfide minerals are through either reduction of Tc(VII) to low-solubility Tc(IV) phases such as TcO 2 ·x H 2 O or by direct precipitation of Tc(VII) as the sparingly soluble sulfide mineral Tc 2 S 7 (Bidoglio and Plano 1985, Lee and Bondietti 1983, Lieser and Bauscher 1988.…”

Section: Published Data Indicate That the 99mentioning

confidence: 99%

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

Pierce¹,

Mattigod²,

Westsik³

et al. 2010

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Executive SummaryPacific Northwest National Laboratory has initiated a waste-form testing program to support the longterm durability evaluation of a waste form for secondary wastes generated from the treatment and immobilization of Hanford radioactive tank wastes. The purpose of the work discussed in this report is to identify candidate stabilization technologies and getters that have the potential to successfully treat the secondary waste stream liquid effluent, mainly from off-gas scrubbers and spent solids, produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Down-selection to the most promising stabilization processes/waste forms is needed to support the design of a solidification treatment unit (STU) to be added to the Effluent Treatment Facility (ETF). To support key decision processes, an initial screening of the secondary liquid waste forms must be completed by February 2010. Later, more comprehensive and longer term performance testing will be conducted, following the guidance provided by the secondary waste-form selection, development, and performance evaluation roadmap. The resulting waste form will be compliant to regulations and performance criteria and will lead to cost-effective disposal of the secondary wastes.This report starts with a brief review of some of the most commonly used solidification formulations that would be candidates for secondary liquid waste streams. In this review, the available data on performance are discussed, and some preliminary recommendations are provided for materials that should undergo additional screening testing. We also 1) discuss options for disposal of WTP secondary solid waste streams, 2) provide a brief overview of standard regulatory test methods used for measuring contaminant leachability and waste-form physical strength (with emphasis on the U.S. Environmental Protection Agency's [EPA's] new methods as a screening tool for comparing waste solidification materials of interest), and 3) provide an overview of factors that must be considered in long-term performance testing, including state-of-the-art characterization tools that can provide the data needed to technically defend predictive modeling simulations of long-term material behavior. The long-term wasteform testing and solid and leachate characterization must be robust enough to effectively predict material performance in the Integrated Disposal Facility over the 10,000-year period of performance for the engineered system. The solidification technologies for liquid waste streams include cement/grout, containerized Cast Stone, phosphate-bonded ceramics, alkali-aluminosilicate geopolymers, hydroceramics, L-TEM, and fluidized-bed steam reforming (FBSR). In addition to these, other mature technologies and two compounds, namely goethite and sodalite (that are still being developed), that show considerable promise as waste forms or getters are also discussed. It is our recommendation, based upon the available literature, that Cast Stone, chemically bonded phosphate ceramics (Ceramicrete...

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Retardation of Technetium and Iodine by Antimony- and Mercury-Containing Minerals

Cited by 18 publications

References 5 publications

Vadose Zone Contaminant Fate and Transport Analysis for the 216-B-26 Trench

Vadose Zone Contaminant Fate and Transport Analysis for the 216-B-26 Trench

Comparison of Sorption Behavior of I^- and TcO^- ₄ on Mg/Al Layered Double Hydroxide

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

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Retardation of Technetium and Iodine by Antimony- and Mercury-Containing Minerals

Cited by 18 publications

References 5 publications

Vadose Zone Contaminant Fate and Transport Analysis for the 216-B-26 Trench

Vadose Zone Contaminant Fate and Transport Analysis for the 216-B-26 Trench

Comparison of Sorption Behavior of I- and TcO- 4 on Mg/Al Layered Double Hydroxide

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

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Product

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Comparison of Sorption Behavior of I^- and TcO^- ₄ on Mg/Al Layered Double Hydroxide