Determination of the Impact of Glycolate on ARP and MCU Operations

Taylor-Pashow, K.; Peters, T. B.; Fondeur, F. F.; Shehee, T. C.; Washington, A. L.

doi:10.2172/1059384

Cited by 2 publications

(6 citation statements)

References 4 publications

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“…The rotor spun at 15,000 rpm for 1.5 minutes to generate an emulsion. In a previous test with CSSX solvent using these conditions, the obtained mean particle distribution (15 µm) 9 was similar to the mean particle size distribution observed in the scale-up test with the NG-CSSX solvent (<18 µM). 10 After waiting for 20 seconds, two visibly distinctive emulsified (turbid) liquid layers formed with the cloudy organic layer sitting on top of the cloudy aqueous layer.…”

Section: Dynamic Interfacial Tension Measurementssupporting

confidence: 80%

Dynamic Surface Tension and Diffusivity Measurements of Ng-CSSX Next Generation Solvent

Fondeur¹,

Peters²

2014

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Since 2008, the Savannah River Site has processed more than four million gallons of radioactive supernatant. To continue compliance with downstream processes, MCU is switching to the improved solvent called Next Generation Solvent (NG-CSSX). The new solvent formulation promises higher cesium removal efficiency and laboratory testing suggests the potential of higher processing rates. Similarly, laboratory testing demonstrated improvements in separation of the solvent from the effluent aqueous streams. To complete implementation at MCU, additional work was needed to develop methods that can measure physical properties relevant to the performance of the new solvent. This work measures two relevant physical properties: static interfacial tension and diffusvity. Both properties play a relevant role in mixing and separating immiscible liquids. This work evaluated the impact of changes in composition or aqueous phase on these physical properties to gauge the sensitivity of the system to the losses of chemical components. This work found that the suppressor, TiDG, when it contacts 10 mM boric acid ionizes and lowers the interfacial tension between NGS-CSSX and boric acid. The interfacial tension lowering is not sufficient to stop NGS-CSSX droplet coalescing. It was also found that the modifier enhances carry-over in the salt simulant of the NGS-CSSX solvent probably through the alcohol group in the modifier molecule. The extractant also assisted in the salt simulant carry-over of the NGS-CSSX after contacting salt simulant. Several literature-published adsorption models were evaluated for fitting the measured static interfacial tension data. It was found that both empirical and thermodynamically derived models fit the data. Because of the limited dataset, a true discrimination of the fitting models was not possible. It was also found that increasing the Isopar ® L concentration in NGS increased the self-diffusivity of the NGS components in NGS-salt simulant emulsions. The diffusion NMR method was able to show and determine the amount of branched and cyclic molecules in Isopar ® L. The method provided an estimate of the NGS viscosity in NGS-salt solution emulsions. The method also gave an estimate of the dynamic interfacial tension of NGS droplets in NGS-salt solution emulsions. The data collected here seems to indicate that the relatively high levels of MaxCalix may lead to excess NGS-CSSX droplets carry over to the salt simulant. It was determined this effect is mainly due to the concentration level and not to additional specific chemical interactions between MaxCalix and the salt simulants. The effect is more pronounced at high energy densities of mixing.

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Section: Dynamic Interfacial Tension Measurementssupporting

confidence: 80%

Dynamic Surface Tension and Diffusivity Measurements of Ng-CSSX Next Generation Solvent

Fondeur¹,

Peters²

2014

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“…The caustic simulant SWS-1-2010 was available from previous work. 2 The absence of potassium and aluminum is not expected to affect results, similar to what was done in that previous work. The neutral simulant was formulated so that pH would be close to neutral, giving a much different environment for glycolate to possibly be taken up into the solvent.…”

Section: Glycolate Distribution Testingsupporting

confidence: 78%

“…This is the same conclusion reached in previous glycolate-ESS testing with other solvents. 2 Two of the Scrub#1 values were slightly outside the typical ranges, but not unusually so. However, the Scrub#1 in the 10,000 ppm sample set has a scrub value noticeably higher than typical.…”

Section: Extraction Scrub Strip Testing Resultsmentioning

confidence: 90%

“…Work in this report follows a past effort where process and materials effects of glycolate were examined using MaxCalix as the extractant and a commercial amine LIX™79 as the suppressor. 2 This work addresses past recommendations from that report.…”

Section: Introductionmentioning

confidence: 88%

“…This work essentially completes the recommended materials testing of the past glycolate testing. 2 If it is found that glycolate in feed to MCU can exceed 10,000 ppm, it is recommended that solvent and materials issues be revisited.…”

Section: Path Forwardmentioning

confidence: 99%

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Glycolate Impacts Testing With New Guanidine (Tidg) Solvent for Mcu

Nash¹,

Peters²,

Washington³

et al. 2014

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Savannah River Remediation (SRR) is evaluating the use of glycolic acid as an alternate reductant (versus formic acid) in a flowsheet for the Defense Waste Processing Facility (DWPF). DWPF recycle would provide a pathway for some glycolic acid to be present in feed to Modular Caustic Side Solvent Extraction Unit (MCU). This report evaluated glycolate impacts on MCU polymer seal material, organic phase separation and glycolic carryover, and Extraction, Scrub, and Strip (ESS), finding no detrimental impacts in any case. The effects of glycolate on several aspects of the solvent extraction system used at MCU have been examined. The conclusions are as follows:  The presence of up to 10,000 ppm of sodium glycolate in a caustic salt solution, or in a neutral pH simulant has no discernable effect on the separation behavior of the solvent/aqueous mixtures, as tested by dispersion experiments.  After contacting the organic solvent with aqueous solutions containing up to 10,000 ppm of glycolate, there was no detectable influx of glycolate into the solvent.  Contacting various organic polymers used at MCU with aqueous solutions containing glycolate showed that there was no glycolate induced swelling in any of the polymer samples.  Extraction, Scrub, Strip (ESS) testing with actual tank samples spiked with up to 10,000 ppm of glycolate showed no effects on solvent performance.

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Determination of the Impact of Glycolate on ARP and MCU Operations

Cited by 2 publications

References 4 publications

Dynamic Surface Tension and Diffusivity Measurements of Ng-CSSX Next Generation Solvent

Dynamic Surface Tension and Diffusivity Measurements of Ng-CSSX Next Generation Solvent

Glycolate Impacts Testing With New Guanidine (Tidg) Solvent for Mcu

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