Elemental characterization of crystalline silicotitanate following Hanford tank waste processing

Campbell, Emily L.; Westesen, Amy; Colon, Ferdinan Cintron; Boglaienko, Daria; Levitskaia, Tatiana G.; Peterson, Reid A.

doi:10.1080/01496395.2020.1777429

Cited by 10 publications

(10 citation statements)

References 25 publications

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“…The breakthrough curves for Sr support batch contact findings for selectivity of CST in a 5.6 M Na simple simulant, where the following selectivity order was determined: Ca > Sr > Pb > Cs; however, Pb breakthrough does not support these findings. It is important to note that these selectivities were measured in a simple simulant matrix incorporating 1.0 M NaOH/4.6 M NaNO 3, which does not account for complexities in tank waste, which appear to have large impacts on removal by CST. , …”

Section: Resultsmentioning

confidence: 99%

Evaluation of Load Behavior for Select Analytes in Hanford Tank Waste

Westesen

Campbell

Fiskum

et al. 2022

Ind. Eng. Chem. Res.

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Crystalline silicotitanate (CST) inorganic ion exchanger is a candidate material for remediation of highly alkaline (pH > 14) aqueous nuclear waste streams containing high sodium concentrations (>5 M). Ion exchange column testing with wastes from Hanford tanks AP-105, AP-107, and AW-102 was carried out to study the uptake of 137Cs to estimate the decontamination factor (DF) value. Additionally, DF values for uptake of Al, Ca, Pb, Np, Pu, U, and Sr were determined and the ion exchange capacity of CST toward these analytes was estimated. Limited data is available on the load behavior of other minor and trace elements with recent CST production lots and this characterization will help improve understanding of the behavior of CST and assist in identifying potential disposition pathways as well as assessing removal capabilities of CST for other components.

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Section: Resultsmentioning

confidence: 99%

Evaluation of Load Behavior for Select Analytes in Hanford Tank Waste

Westesen

Campbell

Fiskum

et al. 2022

Ind. Eng. Chem. Res.

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“…To determine if the chelated tank waste adversely impacted cesium removal, the cesium adsorption results obtained with diluted AN-102 tank waste were compared to an adsorption isotherm generated with a simplified simulant (1.0 M NaOH/4.6 M NaNO 3 ). 20 The diluted AN-102 tank waste results were also compared to batch contact test results with diluted AP-105 (5.9 M Na), AP-107 (5.6 M Na + ), Table 2 provides the concentrations of strontium and other analytes in the diluted AN-102 tank waste feed as well as in the post-batch contacted filtrate solutions at the two-phase ratios. The results show that much of the strontium was removed by CST, and that more strontium was removed when the ratio of liquid to CST was lower.…”

Section: Resultsmentioning

confidence: 99%

“…To determine if the chelated tank waste adversely impacted cesium removal, the cesium adsorption results obtained with diluted AN‐102 tank waste were compared to an adsorption isotherm generated with a simplified simulant (1.0 M NaOH/4.6 M NaNO 3 ) 20 . The diluted AN‐102 tank waste results were also compared to batch contact test results with diluted AP‐105 (5.9 M Na), AP‐107 (5.6 M Na + ), and diluted AW‐102 (5.8 M Na) tank waste supernates, and a more complex (non‐chelated) 5.6 M Na + simulant processed under similar conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Even though strontium removal may not be required, empirical evidence indicates that what little strontium that is dissolved in the non-chelate bearing waste is effectively removed by CST. [19][20][21] Felmy and Mason indicate that most of the strontium that is not chelated is in the form of a dissolved strontium carbonate complex. 22 Some of the tank wastes at the Hanford Site contain relatively high concentrations of chelators which effectively complex strontium in solution.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, radioactive strontium ( 90 Sr) removal is assumed to not be required prior to immobilization of the waste for permanent disposal for waste without chelates. Even though strontium removal may not be required, empirical evidence indicates that what little strontium that is dissolved in the non‐chelate bearing waste is effectively removed by CST 19–21 . Felmy and Mason indicate that most of the strontium that is not chelated is in the form of a dissolved strontium carbonate complex 22…”

Section: Introductionmentioning

confidence: 99%

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Strontium/strontium‐90 removal from c helate‐bearing Hanford tank waste using crystalline silicotitanate

Fiskum

Reynolds²,

Fountain

2022

Env Prog and Sustain Energy

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A study was conducted to evaluate if crystalline silicotitanate (CST) could be used to remove 90Sr from highly chelated tank waste in support of tank waste immobilization. CST was shown to remove cesium from a high‐complexant tank waste, AN‐102 diluted to 5.7 M sodium ions (Na+), comparing well with an existing adsorption isotherm generated with a simplified simulant without chelates. Strontium, barium, and lead were also shown to partially exchange onto the CST, despite their expected chelation and without impacting cesium uptake. The moles of lead loaded onto CST were essentially equivalent to that of cesium. Increasing CST mass resulted in increasing strontium (barium and lead) uptake. Calcium was shown to not exchange, demonstrating strong calcium chelation, not amenable to exchange onto CST.

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The evaluation of aluminum and iron metal oxide settling behaviors for Hanford insoluble solids waste preprocessing

Williams

Peterson

Burns

et al. 2023

Env Prog and Sustain Energy

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The Hanford site is currently one of the largest and most expensive cleanup sites for hazardous, radioactive waste. Over 20% of the waste found at the Hanford site is in the form of a high activity sludge. The insoluble solids in the sludge will need to be concentrated prior to vitrification in the high‐level waste (HLW) melter. This will minimize the amount of liquid that will be evaporated during the melting process and expedite the melter processing rate. One proposed option for concentrating the insoluble solids is gravity settling in the storage tanks. Metal oxide compounds containing aluminum and iron make up the majority of the insoluble solids in the sludge, therefore understanding the behavior of these compounds in various tank waste matrices can facilitate sludge pretreatment options. A study of non‐radioactive slurry solutions containing Al(OH)3 (gibbsite), AlO(OH) (boehmite), and Fe2O3 (iron (III) oxide) was conducted to determine the time dependent interface behavior and settling rates of these compounds. Variations in solids loading and sodium concentration were evaluated to represent waste processing conditions and the results of these settling studies were compared with prior tank waste settling tests. Information gathered from these studies can be used to inform future decisions on sludge treatment processes of the insoluble solids processed at the Hanford site.

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Elemental characterization of crystalline silicotitanate following Hanford tank waste processing

Cited by 10 publications

References 25 publications

Evaluation of Load Behavior for Select Analytes in Hanford Tank Waste

Evaluation of Load Behavior for Select Analytes in Hanford Tank Waste

Strontium/strontium‐90 removal from c helate‐bearing Hanford tank waste using crystalline silicotitanate

The evaluation of aluminum and iron metal oxide settling behaviors for Hanford insoluble solids waste preprocessing

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