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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Theory and application of laser ultrasonic shear wave birefringence measurements to the determination of microstructure orientation in transversely isotropic, polycrystalline graphite materials

Laser ultrasonic line source methods have been used to study elastic anisotropy in nuclear graphites by measuring shear wave birefringence. Depending on the manufacturing processes used during production, nuclear graphites can exhibit various degrees of material anisotropy related to preferred crystallite orientation and to microcracking. In this paper, laser ultrasonic line source measurements of shear wave birefringence on NBG-25 have been performed to assess elastic anisotropy. Laser line sources allow specific polarizations for shear waves to be transmitted – the corresponding wavespeeds can be used to compute bulk, elastic moduli that serve to quantify anisotropy. These modulus values can be interpreted using physical property models based on orientation distribution coefficients and microcrack-modified, single crystal moduli to represent the combined effects of crystallite orientation and microcracking on material anisotropy. Finally, ultrasonic results are compared to and contrasted with measurements of anisotropy based on the coefficient of thermal expansion to show the relationship of results from these techniques.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Mechanism of astatine and bismuth sorption on extraction chromatography resins from nitric acid media

Systematic study of astatine (At) sorption on extraction chromatography resins from nitric acid media has been performed at Texas A&M University. This work covers commercially available resins such as LN, TK400, SR, TRU, and UTEVA. Acquiring an understanding of At behavior in up to 4 M HNO 3 solutions is a key step to develop a rapid and reliable system for At separation and purification. The determined distribution coefficients are greater than 20 for all the resins studied, reaching 400 for TRU and UTEVA resins. The sorption uptake decreases in the order: TRU ≳ UTEVA >TK400 ≳ SR >LN. For each resin a thermodynamic model has been developed to suggest a possible mechanism of At sorption and corresponding sorption constants have been estimated. Literature data along with new results on bismuth (Bi) sorption by studied resins in nitric acid media have been reviewed and a mathematical model to describe its behavior has been suggested. A ratio of corresponding fit functions of At and Bi assigned to the same resin and acidity has been used to estimate separation factors of these elements. Furthermore, only the TRU resin is not suitable for efficient At isolation from Bi, while the other four resins demonstrate promising results.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Extraction chromatography of 225 Ac and lanthanides on N,N-dioctyldiglycolamic acid /1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide solvent impregnated resin

The alpha-emitter 225 Ac (t 1/2 = 9.92 d) is currently under development for targeted alpha-particle therapy of cancer, and accelerator production of 225 Ac via proton irradiation of thorium targets requires robust separations of 225 Ac from chemically similar fission product lanthanides. Additionally, the lanthanide elements represent critical components in modern technologies, and radiolanthanides such as 140 Nd (t 1/2 = 3.37 d) also have potential application in the field of nuclear medicine. The ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf 2 ]), combined with the diglycolamide extractant, N,N-dioctyldiglycolamic acid (DODGAA), was adsorbed on macroporous resin support to produce a solvent impregnated resin (SIR) that was investigated for separations of 225 Ac and lanthanides. The equilibrium distribution coefficients (Kd) of the rare earth elements (Sc(III), Y(III), Ln(III)), 225 Ac(III), Th(IV), and U(VI) on the prepared DODGAA/[Bmim][NTf 2 ]-SIR were determined from batch adsorption experiments in HCl and HNO 3 media. The DODGAA/[Bmim][NTf2]-SIR exhibited preferential uptake of the heavier lanthanide elements while allowing for the separation of the lighter lanthanides. Column separations utilizing the DODGAA/[Bmim][NTf 2 ]-SIR were effective at separating the lighter lanthanides from each other, and separating 225 Ac from a mixture of lanthanides, 213 Bi, and 225 Ra without the need for additional complexing agents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Sulfur-functionalized solid-phase materials for the selective separation of arsenic and selenium

Radioactive arsenic (As) isotopes are of growing interest for applications in nuclear medicine, national security, and environmental research. Recent efforts at the Facility for Rare Isotope Beams (FRIB) have focused on aqueous harvesting of selenium-72,73 ( 72,73 Se) and their daughter isotopes, arsenic-72,73 ( 72,73 As), which are particularly valuable for medical applications and nuclear data studies, respectively. Both conventional isotope production and harvesting methods require chemical separations to purify radioactive As from parent and co-produced Se radioisotopes. While several solid-phase separation methods for As and Se exist, many depend on complex oxidation state control or highly acidic conditions. This study presents results for sulfur-based solid-phase materials selected to enable uptake at lower acidity and eliminate the need for intricate redox chemistry. Specifically, the performance of three covalently bound sulfur-based ligands were evaluated: (1) thiophenol-polystyrene, (2) propanethiol-silica, and (3) thiourea-silica. Uptake characteristics—including distribution coefficients (Dw), kinetics, and column separation behavior—were assessed using 75 Se and 73 As in hydrochloric (HCl) acid and nitric (HNO 3 ) solutions. The resins demonstrated high-yield (>95%) and high-purity As recovery across a range of HCl concentrations. Comparable results in HNO 3 were achieved when combined with anion exchange chromatography. Furthermore, the potential application of these materials for medical isotope generators was also investigated through ligand stability and repeated elution studies. Overall, sulfur leaching from the resins was negligible at the concentrations relevant for these separations but increased with higher acid concentrations.

Arsenic↗
DOE OSTI2016

Selenite sorption by carbonate substituted apatite

The sorption of selenite, SeO 3 2– , by carbonate substituted hydroxylapatite was investigated using batch kinetic and equilibrium experiments. The carbonate substituted hydroxylapatite was prepared by a precipitation method and characterized by SEM, XRD, FT-IR, TGA, BET and solubility measurements. The material is poorly crystalline, contains approximately 9.4% carbonate by weight and has a surface area of 210.2 m 2 /g. Uptake of selenite by the carbonated hydroxylapatite was approximately an order of magnitude higher than the uptake by uncarbonated hydroxylapatite reported in the literature. Distribution coefficients, K d , determined for the carbonated apatite in this work ranged from approximately 4200 to over 14,000 L/kg. A comparison of the results from kinetic experiments performed in this work and literature kinetic data indicates the carbonated apatite synthesized in this study sorbed selenite 23 times faster than uncarbonated hydroxylapatite based on values normalized to the surface area of each material. Furthermore, the results indicate carbonated apatite is a potential candidate for use as a sorbent for pump-and-treat technologies, soil amendments or for use in permeable reactive barriers for the remediation of selenium contaminated sediments and groundwaters.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Adsorptive recovery of neodymium and dysprosium in phosphorous functionalized nanoporous carbon

Here, phosphorus functionalized nanoporous carbon was synthesized from lignin by periodical reactions with potassium hydroxide and triphenylphosphine. It has the BET surface area of 837 m 2 /g and total pore volume 0.41 cm 3 /g along with 0.9 atom% phosphorus. The adsorption of neodymium (Nd (III)) and dysprosium (Dy(III)) were in the range of 335–344 mg/g upto their initial concentration of 500 ppm in water and such adsorption amount is higher than that of majority of the adsorbents reported in literature. The adsorption capacity showed negligible dependency on the solution pH. The distribution coefficients for Nd(III) and Dy(III) were within 1000 to 10,000 mL/g. The adsorption capacity of iron (Fe(III)) under the similar conditions was one order of magnitude lower and it suggests a possible separation of these rare earth elements from iron. The maximum selectivity of separation of Nd(III) and Dy(III) from iron was ca. 32 to 61. Kinetic study revealed that the adsorption of Dy was faster than that of Nd(III). The results of kinetic study were better fit with pseudosecond order kinetics. XPS studies on both Nd(III) and Dy(III)-adsorbed carbons revealed a small shift in the P 2p 3/2 energy level of phosphorus towards higher energy level hereby suggesting a possible formation of metallic phosphates. Additionally, Similar studies on Nd(III) and Dy(III)-adsorbed carbon indicated small amounts carbonates and oxides of rare earth elements that might have also been formed. In conculsion, the overall results suggest that this carbon can be used as a potential sorbent for enrichment and separation of Nd(III) and Dy(III).

36 MATERIALS SCIENCE↗
DOE OSTI2018

Peroxide-treated metal-organic framework templated adsorbents for remediation of high level nuclear waste

Remediation of legacy nuclear waste is one of the greatest challenges faced by the US Department of Energy, with projected cleanup efforts requiring over five decades and hundreds of billions of dollars. New materials are necessary to accelerate waste processing, achieving time and financial savings. Herein we report a peroxide treatment to a Ti metal-organic framework (MOF) and related MOF-templated adsorbents. Furthermore, the resulting materials displayed exceptional affinity for Am(III), achieving distribution coefficients in excess of 10 5 mL/g, and out-performing state-of-the-art benchmarks monosodium titanate (MST) and peroxo-treated modified MST (mMST) for removal of 85 Sr(II) and 239, 240 Pu(IV) from legacy nuclear waste simulant.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Adsorption mechanisms of cesium at calcium-silicate-hydrate surfaces using molecular dynamics simulations

We report understanding the mechanisms of interactions and immobilization of radionuclides in cement systems at the molecular level is key to developing safe and novel solutions for the long-term storage of nuclear wastes. The molecular level adsorption mechanisms of cesium (Cs + ) ions onto tobermorite 9 Å, tobermorite 14 Å, and jennite – three crystalline structural analogues for calcium-silicate-hydrates, the main components in cement-based materials, were investigated using molecular dynamics (MD) simulations. Convergence monitoring of the simulations, using the root mean square displacement with average correlation analysis, indicated that MD trajectories of 10–15 ns were needed given the size of the selected computational cell to properly capture the dynamic process of adsorption. Cs + ions adsorbed as inner-sphere complexes at the tobermorite surfaces, while they showed lower affinity for jennite. The charge and structure of the surface layer strongly influenced the adsorption mechanisms of Cs + ions. Strong association with the hexagonal cavities of the silica sites were seen at the tetrahedral SiO 4 surface of the tobermorite structures. Cs + ion adsorption was attributed to co-ion adsorption at the octahedral CaO 6 surface of tobermorite 9 Å, cation exchange at that of tobermorite 14 Å, and electrostatic interaction with the surface hydroxyl groups for jennite. Distribution coefficients of Cs + ions onto cement pastes derived from molecular dynamics by taking the surface structure and dynamics of Cs + ions directly into account showed a range of overlap with experimental results.

42 ENGINEERING↗
DOE OSTI2024

Anhydrous volatile fatty acid extraction through omniphobic membranes by hydrophobic deep eutectic solvents: Mechanistic understanding and future perspective

Volatile fatty acids (VFAs) derived from arrested anaerobic digestion (AD) can be recovered as a valuable commodity for value-added synthesis. However, separating VFAs from digestate with complex constituents and a high-water content is an energy-prohibitive process. This study developed an innovative technology to overcome this barrier by integrating deep eutectic solvents (DESs) with an omniphobic membrane into a membrane contactor for efficient extraction of anhydrous VFAs with low energy consumption. Here, a kinetic model was developed to elucidate the mechanistic differences between this novel omniphobic membrane-enabled DES extraction and the previous hydrophobic membrane-enabled NaOH extraction. Experimental results and mechanistic modeling suggested that VFA extraction by the DES is a reversible adsorption process facilitating subsequent VFA separation via anhydrous distillation. High vapor pressure of shorter-chain VFAs and low Nernst distribution coefficients of longer-chain VFAs contributed to DES-driven extraction, which could enable continuous and in-situ recovery and conversion of VFAs from AD streams.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Separation of Protactinium Employing Sulfur-Based Extraction Chromatographic Resins

Protactinium-230 (t 1/2 = 17.4 d) is the parent isotope of 230 U (t 1/2 = 20.8 d), a radionuclide of interest for targeted alpha therapy (TAT). Column chromatographic methods have been developed to separate no-carrier-added 230 Pa from proton irradiated thorium targets and accompanying fission products. Results reported within this paper demonstrate the use of novel sulfur bearing chromatographic extraction resins for the selective separation of protactinium. The recovery yield of 230 Pa was 93 ± 4% employing a R 3 P=S type commercially available resin and 88 ± 4% employing a DGTA (diglycothioamide) containing custom synthesized extraction chromatographic resin. The radiochemical purity of the recovered 230 Pa was measured via high purity germanium γ-ray spectroscopy to be >99.5% with the remaining radioactive contaminant being 95 Nb due to its similar chemistry to protactinium. Finally, measured equilibrium distribution coefficients for protactinium, thorium, uranium, niobium, radium, and actinium on both the R 3 P=S type and the DGTA resin in hydrochloric acid media are reported, to the best of our knowledge, for the first time.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

NiAl–MoO 2 S 2 Nanoparticles: Structural Evolution and Mechanistic Insights into High-Performance Selenium Oxyanion Removal across Diverse pH Conditions

Advancing sorbent materials for the selective removal of toxic oxyanions from water requires synthetic control, tunable chemistry, and an atomic-level understanding of structure–function relationships. Here, we report the synthesis and detailed characterization of NiAl–MoO 2 S 2 , a novel layered double hydroxide (LDH) nanomaterial designed for the efficient sequestration of selenium oxoanions (SeO 3 2– and SeO 4 2– ) from complex aqueous environments. The material is synthesized through a room-temperature ion-exchange process, wherein interlayer NO 3 – anions in NiAl–LDH are replaced with MoO 2 S 2 2– clusters, forming high-surface-area, flower-like nanoparticles. Comprehensive structural analysis using the synchrotron X-ray pair distribution function, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy reveals a distinct chemical transformation of intercalated [MoO 2 S 2 ] 2– into [Mo 2 O 2 S 6 ] 2– -like clusters, generating redox-active interlayers that drive selenium capture. This tailored interfacial chemistry underpins the material’s exceptional sorption performance, achieving distribution coefficients (K d ) ≥ 10 6 mL/g and maximum capacities of 343 mg/g for SeO 4 2– and 514 mg/g for SeO 3 2– , outperforming state-of-the-art inorganic sorbents. Importantly, NiAl–MoO 2 S 2 maintains high selectivity and capacity across acidic, neutral, and alkaline pH, efficiently removing selenium from ppm to sub-10 ppb trace levels, even in the presence of competing ions typical of natural and industrial waters. The selenium uptake proceeds via reductive precipitation coupled with the oxidation of molybdenum and sulfide within the LDH framework. This study highlights the power of strategic synthetic modification and interlayer functionalization in LDHs to unlock new structural motifs and redox chemistries, offering a scalable route to advanced materials for environmental remediation.

Adsorption↗
DOE OSTI2020

Superselective Removal of Lead from Water by Two-Dimensional MoS 2 Nanosheets and Layer-Stacked Membranes

Point-of-use (POU) devices with satisfactory lead (Pb 2+ ) removal performance are urgently needed in response to recent outbreaks of lead contamination in drinking water. This study experimentally demonstrated the excellent lead removal capability of two-dimensional (2D) MoS 2 nanosheets in aqueous form and as part of a layer-stacked membrane. Among all materials ever reported in the literature, MoS 2 nanosheets exhibit the highest adsorption capacity (740 mg/g), and the strongest selectivity/affinity toward Pb 2+ with a distribution coefficient K d that is orders of magnitude higher than that of other lead adsorption materials (5.2 × 10 7 mL/g). Density functional theory (DFT) simulation was performed to complement experimental measurements and to help understand the adsorption mechanisms. The results confirmed that the cation selectivity of MoS 2 follows the order Pb 2+ > Cu 2+ >> Cd 2+ > Zn 2+ , Ni 2+ > Mg 2+ , K + , Ca 2+ . The membrane formed with layer-stacked MoS 2 nanosheets exhibited a high water flux (145 L/m 2 /h/bar), while effectively decreasing Pb 2+ concentration in drinking water from a few mg/L to less than 10 μg/L. The removal capacity of the MoS 2 membrane is a few orders of magnitude higher than that of other literature-reported membrane filters. Therefore, the layer-stacked MoS 2 membrane has great potential for POU removal of lead from drinking water.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Impact of a Biological Chelator, Lanmodulin, on Minor Actinide Aqueous Speciation and Transport in the Environment

Minor actinides are major contributors to the long-term radiotoxicity of nuclear fuels and other radioactive wastes. Here in this context, understanding their interactions with natural chelators and minerals is key to evaluating their transport behavior in the environment. The lanmodulin family of metalloproteins is produced by ubiquitous bacteria and Methylorubrum extorquens lanmodulin (LanM) was recently identified as one of nature’s most selective chelators for trivalent f-elements. Herein, we investigated the behavior of neptunium, americium, and curium in the presence of LanM, carbonate ions, and common minerals (calcite, montmorillonite, quartz, and kaolinite). We show that LanM’s aqueous complexes with Am(III) and Cm(III) remain stable in carbonate-bicarbonate solutions. Furthermore, the sorption of Am(III) to these minerals is strongly impacted by LanM, while Np(V) sorption is not. With calcite, even a submicromolar concentration of LanM leads to a significant reduction in the Am(III) distribution coefficient (K d , from >10 4 to ~10 2 mL/g at pH 8.5), rendering it even more mobile than Np(V). Thus, LanM-type chelators can potentially increase the mobility of trivalent actinides and lanthanide fission products under environmentally relevant conditions. Monitoring biological chelators, including metalloproteins, and their biogenerators should therefore be considered during the evaluation of radioactive waste repository sites and the risk assessment of contaminated sites.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2017

Recovery of Rare Earth Elements from Low-Grade Feedstock Leachates Using Engineered Bacteria

The use of biomass for sorption of rare earth elements (REEs) for bioremediation and biomining applications has been the subject of many recent investigations. However, REE adsorption by bioengineered systems has been scarcely documented, and rarely tested with complex natural feedstocks. In this study, we engineered E. coli cells for enhanced cell surface-mediated extraction of REEs. Using Lpp-OmpA as an anchor, up to 16 copies of a Lanthanide binding tag (LBT) per OmpA protein were displayed on the E. coli cell surface, resulting in a 2-fold increase in Tb adsorption capacity compared to control cells. To test the efficacy of engineered E. coli cells to extract REEs from complex source materials, biosorption was performed with leachates from two mine tailings and two rare earth deposits. Although control E. coli cells exhibited preferential adsorption of REEs over most metals, functionalization of the cell surface with LBT yielded several notable advantages. First, the efficiency of REE adsorption from all tested leachates was enhanced with distribution coefficients for individual REEs increased by 2-10 fold. Second, although, Cu, Al, Ga and Pb were found to be the best competitors for REE binding to the E. coli cell surface, LBT-display enhanced the cell surface affinity for REEs over all non-REEs except Cu. Third, LBT-display systematically enhanced the affinity of the cell surface for REEs as a function of decreasing atomic radii, providing a means to separate high value HREEs such as Dy and Tb from more common LREEs such as La. Altogether, our results demonstrate that REE biosorption of high efficiency and selectivity can be achieved by engineering the native bacterial surface.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Adsorption of Rare Earth Elements onto DNA-Functionalized Mesoporous Carbon

The recovery and separation of rare earth elements (REEs) are of national importance owing to the specific usages, high demand, and low supply of these elements. In this research, we have investigated the adsorption of rare earth elements onto DNA-functionalized mesoporous carbons with a BET surface area of 605 m2/g and a median mesopore width of 48 Å. Additionally, three types of single-stranded DNA, one with 100 base units of thymine, another with 20 units of thymine, and the third, a 2000 unit long DNA from salmon milt were grafted on the carboxylated mesoporous carbon surface. All of the DNA-functionalized mesoporous carbons demonstrated higher adsorption of REEs compared to pristine mesoporous carbon and DNA grafted with 100 units of thymine demonstrated slightly higher adsorbed amounts compared to others. Pure neodymium (Nd(III)) adsorption in the aqueous phase demonstrated an adsorbed amount of 110.4 mg/g with respect to the initial concentration of 500 mg/g. A pH variation study with pure Nd(III) demonstrated that the adsorbed amount is higher at elevated pH compared to that at lower pH, thereby suggesting possible recovery at lower pH. Adsorption of a mixture of 16 REEs, including Sc, Lu, Tm, Yb, Er, Ho, Tb, Dy, Y, Eu, Gd, Sm, Ce, Nd, Pr, and La revealed that the adsorbed amount increased with an increase in the atomic weight and metallic radii of elements within the lanthanides. The calculation of the distribution coefficients for all of the equilibrium adsorption amounts suggested that adsorption is more effective in the lower concentration region. The Nd L3-edge X-ray absorption near edge structure (XANES) confirmed a 3+ oxidation state of Nd in the adsorbed phase. The extended X-ray absorption fine structure (EXAFS) confirmed the local atomic structure relaxation of Nd complexes in the adsorbed phase and shortening of the Nd–O bond distance by about 0.03–0.04 Å, which may be associated with their local complexation at the carbon surface.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Time-dependent iodate and iodide adsorption to Fe oxides

Aqueous iodine removal via adsorption to Fe oxides could provide an efficient remedial pathway for vadose zone and groundwater contamination. We conducted a series of macroscopic batch experiments to determine the extent of the time-dependent iodate (IO3-) and iodide (I-) adsorption to four Fe oxides (i.e., ferrihydrite, goethite, magnetite and hematite) at different pH values and solution ionic strengths (IS). The results showed that IO3- adsorption extent [in terms of the average distribution coefficient (Kd) after 2 days of reacting time] followed the order: ferrihydrite (927.5 mL/g) > goethite (84.9 mL/g) > magnetite (23.8 mL/g) > hematite (9.5 mL/g). However, the range of specific surface area (SSA) normalized Kd values was narrow (2 - 4.6 mL/m2), suggesting SSA control over the adsorption extent. The adsorption extent correlated negatively with both pH and IS, implying IO3- outer-sphere adsorption. The adsorption extent increased with time (~27-48%) after 200 days, likely because of interparticle diffusion within aggregates. I- adsorption was insignificant for all Fe oxides. Because of its large SSA, ferrihydrite could be efficient at removing aqueous iodate, potentially decreasing the time of groundwater plume spreading.

Wang, Guohui↗
DOE OSTI2019

Anion-adaptive crystalline cationic material for 99 TcO 4 - trapping

Efficient anion recognition is of great significance for radioactive 99 TcO 4 - decontamination, but it remains a challenge for traditional sorbents. Herein, we put forward a tactic using soft crystalline cationic material with anion-adaptive dynamics for 99 TcO 4 - sequestration. A cucurbit[8]uril-based supramolecular metal-organic material is produced through a multi-component assembly strategy and used as a sorbent for effective trapping of TcO 4 - . Excellent separation of TcO 4 - /ReO 4 - is demonstrated by fast removal kinetics, good sorption capacity and high distribution coefficient. Remarkably, the most superior selectivity among metal-organic materials reported so far, together with good hydrolytic stability, indicates potential for efficient TcO 4 - removal. The structure incorporating ReO 4 - reveals that the supramolecular framework undergoes adaptive reconstruction facilitating the effective accommodation of TcO 4 - /ReO 4 - . The results highlight opportunities for development of soft anion-adaptive sorbents for highly selective anion decontamination.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Synthesis and radiometric evaluation of diglycolamide functionalized mesoporous silica for the chromatographic separation of actinides Th, Pa and U

The separation of Th, Pa, and U is of critical importance in many applications including nuclear power, nuclear waste, environmental and geochemistry, nuclear forensics and nuclear medicine. Diglycolamide (DGA)-based resins have shown the ability to separate many elements, yet, these resins consist of non-covalent impregnation of the DGA molecules on the resin backbone resulting in co-elution of the extraction molecule during separation cycles, therefore limiting their long-term and repeated use. Covalently binding the DGA molecules onto silica is one way to overcome this issue. Herein, measured equilibrium distribution coefficients of normal extraction chromatographic DGA resin and a covalently bound form (KIT-6-N-DGA sorbent) are reported. Several differences are observed between the two systems, the most significant being observed for uranium, which demonstrated significantly lower sorption behavior on KIT-6-N-DGA. These results indicate that U can effectively be separated from Th and Pa using KIT-6-N-DGA, a task that could not be completed with the use of normal DGA alone.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗