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We explored two approaches to recover uranium and plutonium from aqueous solutions at pH 4 and pH 7 using water-soluble star-like polyacrylamide polymers with a dextran core. In the first approach, a solution comprising a neutral or ionomer polymer was mixed with a radionuclide solution to form polymer–metal complexes that were then retained by ultrafiltration (UF) membranes under applied pressure. The same polymers were first deposited on the membrane in the second approach using pressure-driven flow. The applied polymers had an overall diameter of gyration of 120 nm, which exceeded the nominal diameter of the UF membrane pores. The polymers showed a high affinity to uranyl but could also be used to extract Pu from neutral or near-neutral pH solutions. Direct-flow single-step filtration and alpha spectrometry demonstrated that the UF membranes containing star-like copolymers could recover 99% of U and up to 60% of Pu from deionized water after filtering 15 mL solutions containing 25 ppm and 33 ppb of the actinides, correspondingly. The sorption capacity of the polymers for uranium could be measured as 1mg U per mg of the polymer after six subsequent filtration steps. Alpha spectroscopy of the deposited actinides revealed peculiarities of the structural organization of polymers and their complexes with U or Pu, depending on the approach. Though both approaches were efficient, the second approach (deposition of the polymer on the membrane followed by filtration) has an additional advantage of protecting the membrane pores from capillary collapse by filling them with the polymer chains. Therefore, these polymer-modified membranes could be used either in continuous or multi-step filtration process with drying after each step without deterioration of their sorption characteristics. [ABSTRACT FROM AUTHOR]

The research presented here is the development of sensor materials that are applicable for real-time in situ quantification of radiostrontium in aqueous solutions. Two different approaches were applied to prepare highly selective structures for simultaneous extraction and detection of radiostrontium using online detection methods. Online data were acquired with a flow scintillation analyzer IN/US β-Ram model 5 (LabLogic Systems, Inc) with a 30-s dwell time. Both approached utilized the commercially available SuperLig620 solid-phase extractant (IBC Technologies, Inc.) to concentrate the strontium in combination with a scintillator to quantify the radioactivity. [ABSTRACT FROM AUTHOR]

The objective of this research was to develop a method suitable for the determination of aqueous concentrations of radioactive iodine as I2, I-, and IO3-. As one of the primary risk-drivers and contaminants of concern at nuclear waste repositories, the accurate determination of 129I in aqueous systems is of significant concern. The redox-active nature of iodine makes its mobility and fate in the environment difficult to predict, thus underscoring the importance of species-specific determination of iodine concentrations. The developed method couples solid phase extraction with liquid scintillation counting, and scintillating anion exchange with a flow-cell detection system for a sequential measurement of each iodine species. Solid phase extraction disks were impregnated with polyvinylpyrrolidone for the selective extraction and stabilization of I2 with subsequent analysis by liquid scintillation counting. Aqueous I- was concentrated and measured by a previously developed flow-cell system utilizing scintillating anion-exchange resin. A subsequent chemical reduction of IO3- to I- in the effluent was used to quantify IO3- by the same flow-cell system. Nearly quantitative results were found for standardized single-species samples of I2 (95%), I- (101%), and IO3- (91%), respectively, while consistent measurements were obtained for multispecies samples using the developed method and algorithm. [ABSTRACT FROM AUTHOR]