Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Raymond L.

doi:10.2172/1009764

Cited by 5 publications

(13 citation statements)

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“…While the initial sensor optimizations were performed in DI water, the final tests for the sensor selectivity were conducted in a groundwater medium, the water being collected from the well 299-W19-36 at the Hanford site in Washington. The major inorganic constituents present in the groundwater are listed in Table S1 in the Supporting Information. , …”

Section: Methodsmentioning

confidence: 99%

Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion

Chatterjee

Fujimoto

et al. 2020

ACS Sens.

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Rapid, selective, and in situ detection of pertechnetate (TcO 4 − ) in multicomponent matrices consisting of interfering anions such as the ubiquitous NO 3 − and Cl − or the isostructural CrO 4 2− is challenging. Present sensors lack the selectivities to exclude these interferences or the sensitivities to meet detection limits that are lower than the drinking water standards across the globe. This work presents an affinity-based electrochemical sensor for TcO 4 − detection that relies on selective reductive precipitation of aqueous TcO 4 − induced by a 1,4-benzenedimethanethiol capture probe immobilized on an electrode platform. This results in a direct decrease in the electron transfer current, the magnitude of the decrease being proportional to the amount of TcO 4 − added. Using this approach, a detection limit of 1 × 10 −10 M was achieved, which is lower than the drinking water standard of 5.2 × 10 −10 M set by United States Environmental Protection Agency. The proposed approach shows selectivity to the TcO 4 − anion, allowing detection of TcO 4 − from a multicomponent groundwater sample obtained from a well at the Hanford site in Washington (well 299-W19-36) that also contained NO 3 − , Cl − , and CrO 4 2− , without discernably affecting the detection limits.

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Section: Methodsmentioning

confidence: 99%

Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion

Chatterjee

Fujimoto

et al. 2020

ACS Sens.

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“…The major inorganic constituents present in the groundwater are listed in Table S2, Supporting Information. 66 The water was spiked with different concentrations of TcO 4 − ranging from 7.5 × 10 −8 to 7.5 × 10 −6 M. To visually demonstrate the response of 1·SbF 6 to TcO 4 − , a circular carbon film was divided into three segments. 1·SbF 6 was deposited on two segments (marked 1 and 3 in Figure 1), whereas 1·TcO 4 ·xH 2 O was deposited on segment 2.…”

Section: ■ Experimental Detailsmentioning

confidence: 99%

Highly Selective Colorimetric and Luminescence Response of a Square-Planar Platinum(II) Terpyridyl Complex to Aqueous TcO₄^–

et al. 2015

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Molecular recognition of an aqueous pertechnetate (TcO4(-)) anion is fundamentally challenging partly due to the charge-diffuse nature of this anion, which hampers design of new technologies for its separation and detection. To address this gap, simple salts of transition metal complexes that undergo a distinct spectroscopic change upon exposure to aqueous anions were explored. The Pt(II) complex [Pt(tpy)Br]SbF6 (tpy = 2,2';6',2″-terpyridine) undergoes a dramatic color change and intense luminescence response upon TcO4(-) uptake due to concomitant enhancement of Pt···Pt interactions. The spectroscopic response was highly selective and quantitative for aqueous TcO4(-) among other competing anions. Complementary Raman spectroscopy and microscopy techniques, structural determination, and theoretical methods were employed to elucidate the mechanism of this response at the molecular level.

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“…Water used for the batch experiments was sourced from well 299-W19-36 on the Hanford Site. The analysis (Mattigod et al 2010) is shown in Table 3.1. (b) 216 Tetrachloroethene <0.001 <0.001 Alkalinity (as CaCO 3 ) (c) 116,000 Ethyl benzene (d) 0.03 0.06 Uranium (a) 174 p/m xylene (d) Treatments to the water were completed prior to the sorption test and are summarized in Table 3.2.…”

Section: Source Watermentioning

confidence: 99%

“…The resin exchange capacities (Table 3.5), carbon loading capacity (Table 3.6), and iodine concentration of 11.0 µg/L based on previous source water analysis (Mattigod et al 2010) was used to calculate a starting solution-to-solid ratio. It was calculated that ratio #2 should remove all of the iodine in 1 L of source water.…”

Section: Batch Sorption Testsmentioning

confidence: 99%

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Iodine adsorption on ion-exchange resins and activated carbons: batch testing

Parker¹,

Golovich²,

Wellman³

2014

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Among radioactive contaminants, iodine-129 (129 I) is commonly either the top or among the top risk drivers, along with technetium-99 (99 Tc), at radiological waste disposal sites and contaminated groundwater sites where nuclear material fabrication or reprocessing has occurred. Radioactive iodine (129 I) is of environmental concern due to its long half-life (1.6 × 10 7 years), toxicity, and mobility in the environment (Councell et al. 1997). However, there are currently very few approaches that effectively manage risks to human health and the environment. At the Hanford Site in Washington State, radioactive iodine (129 I), a fission product of plutonium, was discharged in 200 West Area disposal cribs. This discharge is responsible for the majority of 129 I contamination found in the groundwater (Zhang et al. 2013). The 200 West Area contains two separate plumes covering 1,500 acres where 129 I concentrations are ~3.5 pCi/L. The objective of this study was to evaluate the efficacy of commercial ion exchange resins and granular activated carbon (GAC) materials which will enable direct removal of all iodine species present in Hanford groundwater through treatment at the 200W pump and treat. Iodine sorption onto seven resins and six carbon materials was evaluated using water from well 299-W19-36 on the Hanford Site. These materials were tested using a range of solution-to-solid ratios. The test results are as follows:  The efficacy of the resin and granular activated carbon materials was less than predicted based on manufacturers' performance data. It is hypothesized that this is due to the differences in speciation previously determined for Hanford groundwater.  The sorption of iodine is affected by the iodine species in the source water. Iodine loading on resins using source water ranged from 1.47 to 1.70 µg/g with the corresponding K d values from 189.9 to 227.0 mL/g. The sorption values when the iodine is converted to iodide ranged from 2.75 to 5.90 µg/g with the corresponding K d values from 536.3 to 2979.6 mL/g. It is recommended that methods to convert iodine to iodide be investigated in fiscal year (FY) 2015.  The chemicals used to convert iodine to iodate adversely affected the sorption of iodine onto the carbon materials. Using as-received source water, loading and K d values ranged from 1.47 to 1.70 µg/g and 189.8 to 226.3 mL/g respectively. After treatment, loading and K d values could not be calculated because there was little change between the initial and final iodine concentration. It is recommended the cause of the decrease in iodine sorption be investigated in FY15.  In direct support of CH2M HILL Plateau Remediation Company, Pacific Northwest National Laboratory has evaluated samples from within the 200W pump and treat bioreactors. As part of this analysis, pictures taken within the bioreactor reveal a precipitate that, based on physical properties and known aqueous chemistry, is hypothesized to be iron pyrite or chalcopyrite, which could affect iodine adsorption. It is recommended these mater...

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Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

Cited by 5 publications

References 0 publications

Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion

Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion

Highly Selective Colorimetric and Luminescence Response of a Square-Planar Platinum(II) Terpyridyl Complex to Aqueous TcO₄^–

Iodine adsorption on ion-exchange resins and activated carbons: batch testing

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Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

Cited by 5 publications

References 0 publications

Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion

Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion

Highly Selective Colorimetric and Luminescence Response of a Square-Planar Platinum(II) Terpyridyl Complex to Aqueous TcO4–

Iodine adsorption on ion-exchange resins and activated carbons: batch testing

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Highly Selective Colorimetric and Luminescence Response of a Square-Planar Platinum(II) Terpyridyl Complex to Aqueous TcO₄^–