Neguib M. Hassan

Cesium Removal from Hanford Tank Waste Solution Using Resorcinol‐Formaldehyde Resin

Abstract Experiments with Hanford actual waste sample from Tank 241‐AW‐101 and resorcinol‐formaldehyde resin demonstrated that up to 208 BV of cesium (137Cs) can be removed in a single‐pass through an ion exchange column before a 50% breakthrough occurs. This loading performance for the resorcinol‐formaldehyde resin was better than that previously obtained for the baseline resin (SuperLig® 644) under the same experimental conditions. The elution of the resorcinol‐formaldehyde resin with 0.5 M HNO3 was effective requiring only 16.5 BV to elute 99% of the cesium (i.e. C/Co value <0.01) loaded on the column. The peak concentration for 137Cs occurred between 4 and 6 BV with concentration approximately 100 times that of the feed. The metal ions found in the eluate solution above their detection limits were Al, B, Ca, Cs, Na, and Si. Nitrate was the only anion detected and 238Pu, 239/240Pu, and U were slightly enriched in the eluate solution. Large sample dilutions prevented the detection of other species.

Removal of cesium from alkaline waste solution. Part I - Batch ion exchange study

Summary Batch ion exchange tests have been employed to evaluate the ability of SuperLig® 644 resin to remove 137Cs from highly alkaline nuclear waste solution. The batch sorption data indicated the SuperLig® 644 resin has a relatively high sorption affinity for cesium with a predicted number of bed volumes required to reach 50% breakthrough in a column operation (generally known as λ value) of ∼400 based on an initial total cesium concentration of 12.1 μg/mL. The sorption data also obey the Freundlich and Dubinin–Radushkevich isotherms.

SuperLig 644 equilibrium sorption data for cesium from Hanford tank waste supernates

SuperLigŇ 644 ion exchange resin is currently being evaluated for cesium (137Cs) removal from radioactive Hanford tank wastes. To assess the performace of the resin in column configuration, a multiple batch contact method was used to determine the equilibrium distribution coefficients (Kd) and percent removal for 137Cs from highly alkaline waste solutions obtained from the Hanford Site. The equilibrium loading data were interpreted in terms of Freundlich and Dublin-Radushkevics (D-R) isotherms. The equations fit the experimental data remarkably well considering the complexity of the Hanford tank waste compositions. The mean energy of adsorption and total resin capacity were calculated. The mean free energy for adsorption of cesium from Hanford tanks was ~9 kJ/mol. The total exchange capacity of the SuperLigŇ 644 resin ranged from 0.72 to 3.46 mmole/g resin, depending on the Hanford tank composition. The Kd results reveal that SuperLigŇ 644 resin in highly selective for cesium in the presence of relatively high concentrations of sodium and potassium salts.

Ion exchange removal of cesium from Hanford tank waste supernates with SuperLig ® 644 resin

SuperLigÒ 644 ion exchange resin is currently being evaluated for cesium (137Cs) removal from radioactive Hanford tank waste supernates as part of the River Protection Project. Testing was performed with actual Hanford tank wastes of widely different compositions using two identical ion exchange columns connected in series each containing approximately 5.5-6.5 ml of SuperLigŇ 644 resin. The ion exchange columns utilized the same resin material that was eluted between the column tests. This was done to demonstrate the performance of the SuperLigŇ 644 resin for cesium removal from waste samples of different compositions, determine the loading and elution profiles, and to validate design assumptions for full-scale column performances. Decontaminated product solutions generated at the same operating temperature and constant residence times (bed volumes per hour) exhibited the same chemical compositions as their feed samples. The compositions of eluate solutions were generally as expected with the exception of uranium and total organic carbon, which where concentrated by the resin. Development of a pretreatment method for the SuperLigŇ 644 resin has been critical to successful column operation with different waste solutions.

Multiple Ion Exchange Column Tests for Technetium Removal from Hanford Site Tank 241‐AW‐101 with Superlig® 639 Resin

Abstract Five cycles of loading, elution, and regeneration were performed to remove technetium in the form of pertechnetate from a Hanford waste sample retrieved from Tank 241‐AW‐101 using SuperLig® 639 resin. The waste sample was diluted to 4.95 M Na+ and then processed to remove 137Cs through dual ion exchange columns, each containing 15 mL of SuperLig® 644. To remove technetium, the cesium decontaminated solution was processed downwards through two ion exchange columns, each containing 12 mL of the SuperLig® 639 resin. The columns, designated as lead and lag, each had an inside diameter of 1.45 cm and a height of 30 cm. The columns were loaded in series, but were eluted and then regenerated separately. The average technetium loading for the cycles was 250 BV (bed volume) at 10% breakthrough. There was no significant difference in the loading performances among the five cycles. The percent removal of technetium in the pertechnetate form (TcO4 −) was >99.94% and the average de‐contamination factor (DF) was ∼1.7 × 103. Approximately 99% of the TcO4 − loaded on the resin was eluted with <15 BV of deionized water at 65°C.

Technetium Removal from Hanford and Savannah River Site Actual Tank Waste Supernates with Superlig® 639 Resin

SuperLig 639 elutable, organic resin was selected for technetium (as pertechnetate ion) removal from Hanford Site radioactive waste samples as part of the River Protection Project—Waste Treatment Plant (RPP-WTP) design. In support of the RPP-WTP flow sheet development, column tests have been performed at the Savannah River Technology Center with SuperLig 639 resin using actual Hanford Site tank waste samples. The resin was shown to be highly effective at pertechnetate removal from these caustic, high-sodium, aqueous waste samples. Pertechnetate ion was subsequently eluted from the columns with water. An additional column test conducted on a Savannah River Site waste sample revealed exceptional performance, presumably due to the fact that lower concentrations of competing anions (primarily nitrate) were present in the sample.

SuperLig® 644 resin accelerated aging study

SuperLig® 644 resin was exposed to simulated Hanford waste solution under air atmosphere or in protated inert environment, and in 0.5M HNO3 solution for 15 days and 45 °C. The degradation was evaluated by cesium batch distribution measurement.

Adsorption of Radon and Water Vapor on Commercial Activated Carbons

Abstract Equilibrium adsorption isotherms are reported for radon and water vapor on two commercial activated carbons: coconut shell Type PCB and hardwood Type BD. The isotherms of the water vapor were measured gravimetrically at 298 K. The isotherms of radon from dry nitrogen were obtained at 293, 298, and 308 K while the data for the mixture of radon and water vapor were measured at 298 K. The concentrations of radon in the gas and solid phases were measured simultaneously, once the adsorption equilibrium and the radioactive equilibrium between the radon and its daughter products were established. The shape of the isotherms was of Type III for the radon and Type V for the water vapor, according to Brunauers classification. The adsorption mechanism was similar for both the radon and the water vapor, being physical adsorption on the macropore surface area in the low pressure region and micropore filling near saturation pressure. The uptake capacity of radon decreased both with increasing temperature and r...

Separation of n-Paraffins from Kerosene-Range Feedstock by Adsorption on Fixed-Bed Urea

Abstract Experimental breakthrough curves have been obtained for n-paraffins from kerosene-range feedstocks on fixed-bed urea. The feedstocks used were unified heavy kerosene, straight-run kerosene, and naphtha-kerosene blend with initial n-paraffin contents of 29.31, 31.87, and 34.71 wt%, respectively. The breakthrough curves were measured in the temperature range 283–303 K and the feed flow rates 0.8–2.5 cm3/min. The dynamic parameters for adsorption, such as the height of the mass transfer zone, the dynamic capacity, and the column efficiency, were determined from experimental breakthrough curves. The results from this study indicated that the n-paraffin molecules from unified heavy kerosene were more strongly adsorbed than those from straight-run kerosene or naphtha-kerosene blend, thereby revealing that n-paraffin adsorption on urea increased with the molecular length of the hydrocarbon. The values of the estimated apparent diffusion coefficients for n-paraffin from naphtha-kerosene blend ranged from...

Effect of temperature on SuperLig® 644 cesium removal from simulated Hanford tank waste supernate

Batch kinetic and column experiments have been carried out at 25, 35, and 45 °C to examine the effect of temperature on SuperLig® 644 cesium (Cs) removal from simulated Hanford tank waste supernate. The simulated solution mimicked the composition of the low-activity waste supernate from tank 241-AN-105 in the U.S. DOE Hanford site. Small quantities of toxic metals, such as Cd, Cr, Fe, and Pb were spiked into the simulant to evaluate the metals competitiveness with Cs for sorption on SuperLig® 644 resin. The results indicated that the temperature affects the removal of Cs and metal ions, although the effect was not the same for all metal ions. The extent of Cs removal decreased with an increase in temperature. The Cs capacity at breakthrough point was 0.015, 0.013, and 0.011-mmole/g dry resin at 25, 35 and 45 °C, respectively. The column was effectively eluted to less than 1% (0.1 C/C0) of the feed concentration with approximately 10 BVs of 0.5M nitric acid. The resin showed limited affinity for toxic metal ions (Cr, Cd, Fe, and Pb) as compared to Cs. Based on the batch kinetic data, the Cs uptake of the resin was not hampered by the presence of the toxic metals in solution.