Insight into ion exchange column dynamics through application of an analytical model of system performance

Williams

et al. 2023

Ind. Eng. Chem. Res.

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Crystalline silicotitanate (CST) ion exchange media is currently utilized in the tank side cesium removal (TSCR) system on the Hanford site to remove Cs-137 from the tank waste supernate. As the main dose contributor to the liquid supernate in Hanford tank waste, it is necessary to remove the Cs-137 to expedite low activity waste processing and immobilization. Ongoing batch contact experiments with CST have been done to tease out the impact of group II metals, anions, potassium, and temperature on Cs removal to better understand bounding conditions for operations as well as aid in development of a wholesome isotherm model to predict Cs behavior in the tank waste. This paper discusses the impact of Na concentration on Cs exchange and provides insight into the challenges associated with activity coefficient estimations for modeling Cs distribution in tank waste matrices.

Section: Discussionmentioning

confidence: 99%

“…Without running a full ion exchange column test, which is costly and time-consuming, the batch contact work herein should suffice for estimation of load behavior in a process setting. 18…”

Section: ■ Conclusionmentioning

confidence: 99%

Effect of Na Concentration on Cs Distribution with Crystalline Silicotitanate in Tank Waste Simulants

Campbell

Williams

et al. 2023

Ind. Eng. Chem. Res.

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“…An effluent was collected in a bulk container, where the concentration in the effluent is an average of the full sampling interval or using a fraction collector. The column data was fit using an approximation from Hougen and Marshall, which has been successfully applied to well-behaved column systems previously. , Fits, where possible, were done individually on iodate (first 10% breakthrough) or iodide (remaining 90% breakthrough). The data was fit using eq to minimize the sum of squares in Excel using the Solver function. C BV C 0 = 1 2 [ 1 + erf false( k 1 BV − k 2 z false) ] where C BV is the effluent concentration after a number of BV, C 0 is the column inlet iodine concentration, erf is the Excel error function, k 1 is the column fitting parameter defined in eq , BV is the bed volumes passed, k 2 is the column fitting parameter as defined in eq , and z is the column length…”

Section: Methodsmentioning

confidence: 99%

“…The column data was fit using an approximation from Hougen and Marshall, 53 which has been successfully applied to wellbehaved column systems previously. 54,55 were done individually on iodate (first 10% breakthrough) or iodide (remaining 90% breakthrough). The data was fit using eq 6 to minimize the sum of squares in Excel using the Solver function.…”

Section: Purolite A530e (A530)mentioning

confidence: 99%

Iodine Removal from Carbonate-Containing Alkaline Liquids Using Strong Base Resins, Hybrid Resins, and Silver Precipitation

Asmussen

Cordova

et al. 2023

Ind. Eng. Chem. Res.

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The ability of several material types to remove aqueous iodine from a mildly alkaline, carbonate-rich nuclear waste stream was evaluated: strong base anion exchange resins (SBARs), hybrid resins, Ag-containing materials, and Bi-containing hybrid resins. A combination of batch testing and flow-through column testing was used in the evaluation. In batch testing, hybrid resins CHM-20, SIR-110-CE, and RTBI were shown to have high efficiency for the removal of both iodide and iodate simultaneously, while Ag-containing materials and SBAR demonstrated high capacity for iodide removal. One example of each material type (CHM-20, A532E, and Ionex 400) was further evaluated for their sorption isotherms and column performance. The Langmuir isotherm, or a Langmuir−Freundlich hybrid isotherm, best described the sorption of iodide to the CHM-20 hybrid resin and Purolite A532E. The Freundlich isotherm best described the uptake of iodate to CHM-20 and A532E and for both iodide and iodate to Ag-containing Ionex 400. In column testing, Purolite A532E had exceptional performance for overall iodide removal. However, with the capacity demonstrated, the A532E resin would exceed class C waste classification before breakthrough initiated, and column change-outs in processing would be dictated by eventual waste classification, not breakthrough. Ionex 400, a Ag-zeolite, was observed to degrade over time under mild alkaline column conditions, whereas the hybrid CHM-20 was limited in the single pass through design and would be best suited for applications where iodide and iodate are present and recirculation of the column effluent is feasible. This work highlights the feasibility of commercially available materials to separate radioiodine from liquid environments.

“…[4][5][6][7] Recent development of a scaled, tankside cesium removal prototype utilizing crystalline silicotitanate has facilitated treatment of the liquid fraction of the waste. [8][9][10] With the successful startup of the tank-side Cs removal facility, the next significant challenge will be associated with treatment of the balance of the insoluble fraction of the waste that contains most of long lived radionuclides such as plutonium, uranium and neptunium. 11 A number of processes utilizing dissolution and leaching and have been developed to reduce the mass of insoluble solids present, 12,13 however all of these processes ultimately rely upon solid-liquid separation to produce a concentrated slurry for eventual disposition.…”

mentioning

confidence: 99%

Impact of gel concentration on filter fluxes in microfiltration of Hanford tank wastes and simulants

Env Prog and Sustain Energy

Geeting

Brooks

et al. 2023

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Treatment processes have been proposed that will utilize crossflow filtration to concentrate sludge waste streams at the Department of Energy's Hanford Site. Challenges associated with solid–liquid separation of the waste streams drive a necessary evaluation of available Hanford high level waste (HLW) filtration data. Limiting flux conditions during crossflow filtration are elucidated with the formation of a cake layer on the membrane surface. A mass transfer coefficient between the gel and bulk concentrations plays a critical role in determining filter flux. A correlation between the gel concentration and mass transfer coefficient is made to assist in determining filter performance of select HLW streams. As a process alternative to crossflow filtration, gravity settling of waste streams may be deployed as a solid–liquid separation technique. However, this results in a contrasting performance with the centrifuged solids concentration. A method was developed to estimate expected filtration and settling performance based on physical characterization data for Hanford tank waste samples. By assessing the estimated processing performance of HLW, technical support can be provided during flowsheet planning.