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At least 163 records · Page 9

All sources NASA NTRS DOE OSTI

DOE OSTI2020

Recent advances in polymeric facilitated transport membranes for carbon dioxide separation and hydrogen purification

Membrane and membrane process have been widely considered as one of the best candidates for mitigating CO 2 emissions from the combustion or utilization of fossil fuels. Various amine-containing polymers constitute an important class of membranes, where the highly selective CO 2 transport is achieved by the facilitated transport mechanism. In this review, the amine–CO 2 chemistry is discussed in conjunction with the mechanism of the reaction-mediated CO 2 transport. A wide variety of amine-containing polymers are discussed based on two synthesis motifs: (a) polyamines with amino groups covalently bound to the polymer backbone and (b) small molecule amines embedded in a polymer matrix. This review concludes with the remarks on the facilitated transport membranes for post-combustion carbon capture (CO 2 /N 2 ) and hydrogen purification (CO 2 /H 2 ).

42 ENGINEERING↗

DOE OSTI2020

Purification and characterization of a native lytic polysaccharide monooxygenase from Thermoascus aurantiacus

Lytic polysaccharide monooxygenases (LPMOs) have emerged as key proteins for depolymerization of cellulose. These copper-containing enzymes oxidize C-1 and/or C-4 bonds in cellulose, promoting increased hydrolysis of the oxidized cellulose chains. The LPMO from Thermoascus aurantiacus, a thermophilic ascomycete fungus, has been extensively studied and has served as a model LPMO. A method was developed to purify the LPMO from culture filtrates of T. aurantiacus along with its native cellobiohydrolase and endoglucanase. The activity of the purified LPMO was measured with a colorimetric assay that established the T opt of the native LPMO at 60 °C. Purification of the components of the T. aurantiacus cellulase mixture also enabled quantification of the amounts of cellobiohydrolase, endoglucanase and LPMO present in the T. aurantiacus culture filtrate, establishing that the LPMO was the most abundant protein in the culture supernatants. Here, the importance of the LPMO to activity of the mixture was demonstrated by saccharifications with Avicel and acid-pretreated corn stover.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2014

Rapid separation and purification of uranium and plutonium from dilute-matrix samples

This work presents a streamlined separation and purification approach for trace uranium and plutonium from dilute (carrier-free) matrices. The method, effective for nanogram quantities of U and femtogram to picogram quantities of Pu, is ideally suited for environmental swipe samples that contain a small amount of collected bulk material. As such, it may be applicable for processing swipe samples such as those collected in IAEA inspection activities as well as swipes that are loaded with unknown analytes, such as those implemented in interlaboratory round-robin or proficiency tests. Additionally, the simplified actinide separation could find use in internal laboratory monitoring of clean room conditions prior to or following more extensive chemical processing. We describe key modifications to conventional techniques that result in a relatively rapid, cost-effective, and efficient U and Pu separation process. We demonstrate the efficacy of implementing anion exchange chromatography in a single column approach. We also show that hydrobromic acid is an effective substitute in lieu of hydroiodoic acid for eluting Pu. Lastly, we show that nitric acid is an effective digestion agent in lieu of perchloric acid and/or hydrofluoric acid. A step by step procedure of this process is detailed.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2022

Inorganic resins enable the increased purification efficiency of 82 Sr from rubidium targets for use in PET imaging isotope production

The 82 Sr/ 82 Rb generator system has found use in positron emission tomography (PET) imaging of myocardial perfusion. 82 Sr is produced by proton irradiation of Rb metal/RbCl salt followed by chemical separation. Inorganic ion-exchangers were synthesized by hydrothermal methods and evaluated for the purification of accelerator-produced 82Sr from a RbCl target and co-produced impurities like 75 Se, Fe, Cr, and Ni. A process consisting of removal of bulk RbCl using sodium nonatitanate (SNT), then removal of remaining tracers of Rb and Se using poorly crystalline silicotitanate (pCST) is suitable for 82 Sr separation and achieves higher purity of 82 Sr vs. commonly used organic resins.

43 PARTICLE ACCELERATORS↗

DOE OSTI2025

Actinium purification from elemental components of stainless steel and aluminum

Radioisotopes of actinium are valuable because of their potential use in the medical industry. Actinium-225 shows promise for treating disease—like cancer—via targeted alpha therapy (TAT), and the longer-lived actinium-227 is the parent of two radionuclides with potential application in TAT radiopharmaceuticals, thorium-227 and radium-223. Continuing progress in the development of these medical applications requires robust and diverse methods for extracting and purifying actinium from a wide range of matrices. Further, to define the strengths and limitations of separation methods commonly employed in actinium processing, we characterized the performance of ion exchange and extraction chromatographic steps for removing contaminants found in stainless steel (chromium, iron, nickel, and silicon) and aluminum from actinium-227. While AG-MP1 anion exchange resin with HCl (aq) successfully removed iron, cation exchanger AG 50W-X8 removed most other contaminants. The most persistent contaminant was aluminum, which was removed using a DGA Normal extraction resin. These results are presented within the context of applying that methodology toward actinium purification strategies.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Ra-226 extraction and purification from simulated uranium tailings

Growing demand for Ac-225 has outstripped current production, increasing interest in alternative production routes. Furthermore, these often rely on irradiations of Ra-226, yet Ra-226 supplies are also limited. Uranium tailings provide an abundant source of Ra-226, though separation from these complex matrices remains challenging. A laboratory-scale process was developed to recover Ra-226 from simulated U-tailings. After acid leaching, Ra remained adsorbed on refractory oxides and silicates. An additional CaCl₂ leach of the residue raised recovery to ~ 64%. Subsequent purifications, including precipitation, ion-exchange, and extraction chromatography (TK101), achieved chemical yields up to 73 ± 7%, producing 7.68 ± 0.1 µCi of high-purity Ra-226.

and nuclear chemistry↗

DOE OSTI2019

Performance efficiency and kinetic studies of water purification using ZnO and MgO nanoparticles for potassium permanganate

Zinc oxide (ZnO) and Magnesium oxide (MgO) nanoparticles (NPs) have been synthesized by solid–solid reaction technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) were used to investigate the structural properties of ZnO and MgO NPs. XRD indicates that structural of ZnO NPs has a hexagonal structure with space group P63mc. On the other hand, MgO NPs is cubic structure with space group Fm 3-bar m. The photocatalytic efficiency of both ZnO and MgO NPs as a catalyst was illustrated by studying the extreme quantity of potassium permanganate (KMnO{sub 4}) degradation rate in wastewater. KMnO{sub 4} achieved 17% and 25% degradation rate in 180 min for ZnO and MgO NPs, respectively. The experimental data were examined by the kinetic models of pseudo-first and second order as well as intra-particle diffusion. The obtained data is expressed well by the second-order kinetic model for both NPs. Moreover, according to the experimental results, MgO NPs has high-performance water purification as a comparison of ZnO NPs effect.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2019

Expression and purification of affinity-tagged variants of the photochemical reaction center from Heliobacterium modesticaldum

The heliobacterial photochemical reaction center (HbRC) from the chlorophototrophic Firmicutes bacterium Heliobacterium modesticaldum is the only homodimeric type I RC whose structure is known. Using genetic techniques recently established in our lab, we have developed a rapid heterologous expression system for the HbRC core polypeptide PshA. Our system relies on rescue of the non-chlorophototrophic ΔpshA::cbp2p - aph3 strain of Hbt. modesticaldum by expression of a heterologous pshA gene from a replicating shuttle vector. Furthermore, we constructed two tagged variants of PshA, one with an N-terminal octahistidine tag and one with an internal hexahistidine tag, which facilitate rapid purification of pure, active HbRC cores in milligram quantities. We constructed a suite of shuttle vectors bearing untagged or tagged versions of pshA driven by various promoters. Surprisingly, we found that the eno and gapDH_2 promoters from Clostridium thermocellum drive better expression of pshA than fragments of DNA derived from the region upstream of the pshA locus on the Hbt. modesticaldum genome. This “ pshA rescue” strategy additionally provided a useful window into how Hbt. modesticaldum regulates pigment synthesis and growth rate when chlorophototrophic output decreases.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2016

Refined hyperentanglement purification of two-photon systems for high-capacity quantum communication with cavity-assisted interaction

Hyperentanglement, defined as the entanglement in multiple degrees of freedom (DOFs) of a photonic quantum system, has attracted much attention recently as it can improve the channel capacity of quantum communication largely. Here we present a refined hyperentanglement purification protocol (hyper-EPP) for two-photon systems in mixed hyperentangled states in both the spatial-mode and polarization DOFs, assisted by cavity quantum electrodynamics. By means of the spatial (polarization) quantum state transfer process, the quantum states that are discarded in the previous hyper-EPPs can be preserved. That is, the spatial (polarization) state of a four-photon system with high fidelity can be transformed into another four-photon system with low fidelity, not disturbing its polarization (spatial) state, which makes this hyper-EPP take the advantage of possessing a higher efficiency.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2017

Electron linear accelerator production and purification of scandium-47 from titanium dioxide targets

Here, the photonuclear production of no-carrier-added (NCA) 47 Sc from solid Nat TiO 2 and the subsequent chemical processing and purification have been developed. Scandium-47 was produced by the 48 Ti(γ,p) 47 Sc reaction with Bremsstrahlung photons produced from the braking of electrons in a high-Z (W or Ta) convertor. Production yields were simulated with the PHITS code (Particle and Heavy Ion Transport-code System) and compared to experimental results. Irradiated TiO 2 targets were dissolved in fuming H 2 SO 4 in the presence of Na 2 SO 4 and 47 Sc was purified using the commercially available Eichrom DGA resin. Typical 47 Sc recovery yields were >90% with excellent specific activity for small batches (<185 MBq batches).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

Improved titanium-44 purification process for establishing a high apparent molar activity titanium-44/scandium-44 generator

44 Sc-radiopharmaceuticals are gaining more interest but still lack availability. The proof of principle of a 44 Ti/ 44 Sc generator, which can produce 44 Sc daily, has been established but with some limitations and drawbacks. Despite recent advances, separation of 44 Ti from massive quantities of scandium target material is still cumbersome. Here, in this work, the improved radiochemical separation of 44 Ti from residual scandium target material was carried out by precipitation of Sc with fluoride ions. Furthermore, two approaches were used to set up a high apparent molar activity small-scale generator. The first method relied on extraction chromatography for fine purification using a DGA resin, followed by loading of the purified 44 Ti onto a ZR resin column. In the second method, 44 Ti was loaded on the ZR resin directly after the precipitation step. This second method was used to set up a generator of 370 kBq and evaluate by radiolabeling. An apparent molar activity of 2 MBq/nmol was obtained for the radiolabeling with DOTA, the most common and suitable chelate for scandium. This result is comparable with previously published data on 44m/44 Sc.

44Sc↗

DOE OSTI2015

Co-purification of arrestin like proteins with alpha-enolase from bovine myocardial tissues and the possible role in heart diseases as an autoantigen

Aim: Previously, we reported that visual arrestin co-purified with glycolytic enzymes. The aim of this study was to analyze the co-purification of arrestin like proteins (ALP) in bovine cardiac tissues with enolases. Methods: The soluble extract of bovine myocardial tissues from different regions such as left and right atriums and ventricles of the bovine heart (n = 3) was analyzed by ACA-34 gel filtration, immuno-affinity column, SDS-PAGE, ELISA, western blot and a sandwich immune assay for quantification of ALP and sequence analysis. Results: We observed that; 1) The cardiac muscle contained a 50 kDa ALP at a concentration of 751 pg/mg of soluble protein extract, 2) ALP purified, by immunoaffinity, contained alpha-enolase of 48 kDa confirmed by protein sequence analysis; 3) Cardiomyocyte cells exposed to anti arrestin and anti enolase monoclonal antibodies showed decreased proliferation in vitro, 4) High level of autoantibodies were detected by ELISA (3.57% for arrestin and 9.12% for α-enolase) in serum of patients with infarcted heart disease. Conclusion: We suggest a possible interaction between ALP and alpha-enolases yielding a complex that may be involved in the induction of cardiac autoimmune diseases. - Highlights: • We examine a possible interaction between arrestin like protein and alpha-enolases in cardiomyocyte. • We demonstrated the effect of antibodies against arrestin and enolase on cardiomyocyte cell proliferation. • We suggest that this proteins complex may be involved in the induction of cardiac autoimmune diseases.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2019

Optimizing complexity in the kinetic modelling of integrated flue gas purification for pressurized oxy-combustion

A 5-step mechanism and a corresponding kinetic model are presented for integrated flue gas purification, where SOx and NOx are removed during pressurized oxy-coal combustion. Three coupled subsystems (‘blocks”) of gas–liquid transformations are considered: 1) oxidation of NO to NO 2 and dissolution of NO 2 in water; 2) dissolution of SO 2 in the water; and 3) interactions between S- and N- containing substances in the liquid phase. The model has been formulated in terms of only species that can be experimentally measured (model of optimal complexity). Subsystem I is limiting regarding NO removal. Subsystem II is very fast in comparison with the other subsystems and can be treated separately. Analytical expressions for all independent subsystems have been found and compared with computational results for the whole system. The temporal domain of validity of all these subsystems is presented. Finally, the validity of the NO 2 quasi-steady-state assumption is verified, and it is reported that variables such as NO, NO 2 and HNO 3 can be considered decoupled from the whole system since they appear in only Subsystem I, while HSO 3 - and HNO 2 are coupled. The presented kinetic model was verified experimentally by determining the 1:1 ratio of HNO 2 and HNO 3 , in gas–liquid NO-O 2 interaction. Additionally, new experimental facts on kinetic orders and stoichiometry between HNO 2 and HSO 3 - have been used to optimize the model. It is concluded that all NO x - SO x interactions can be essentially grasped by a sequence of only 4 irreversible reactions considering, in addition, the 5th reaction, i.e. the fast ‘SO 2 -water’ equilibrium.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Molecularly engineered ZnO–carbon nanosheets from fumaric acid precursors for efficient photocatalytic water purification

The photocatalytic breakdown of organic contaminants is crucial for the development of water purification technology. Zinc oxide (ZnO) is an extensively researched photocatalyst; however, its efficacy is hindered by rapid charge recombination and limited utilization of UV irradiation. Resolving these issues necessitates integrating ZnO with conductive carbon phases via scalable, low-temperature synthesis. We provide a molecularly designed sol–gel method that converts zinc–fumarate coordination networks into two-dimensional ZnO–carbon nanosheets utilizing solely aqueous precursors and mild annealing temperatures (400–600 °C). This method utilizes fumaric acid as a dicarboxylate linker and polyvinylpyrrolidone (PVP) as a structural carbon source to produce ultrathin wurtzite ZnO nanosheets embedded inside an amorphous carbon matrix. The resultant ZnO-C hybrid achieves nearly complete methylene blue degradation within 10 min under UV-A illumination, demonstrating first-order kinetics and outstanding recyclability. Compared with commercial ZnO, the ZnO–C nanosheets exhibit comparable rapid photocatalytic degradation, enhanced adsorption behavior, a porous nanosheet morphology, and an integrated ZnO–carbon interfacial structure. These findings provide a viable molecular-templating approach to fabricating various metal oxide–carbon photocatalysts and underscore substantial enhancements in semiconductor efficacy in eco-friendly water treatment systems.

Ozcan, Muca [ORNL] (ORCID:0000000320020474)↗

DOE OSTI2015

Energy requirements of the switchable polarity solvent forward osmosis (SPS-FO) water purification process

A model was developed to estimate the process energy requirements of a switchable polarity solvent forward osmosis (SPS FO) system for water purification from aqueous NaCl feed solution concentrations ranging from 0.5 to 4.0 molal at an operational scale of 480 m3/day (feed stream). The model indicates recovering approximately 90% of the water from a feed solution with NaCl concentration similar to seawater using SPS FO would have total equivalent energy requirements between 2.4 and 4.3 kWh per m 3 of purified water product. The process is predicted to be competitive with current costs for disposal/treatment of produced water from oil and gas drilling operations. As a result, once scaled up the SPS FO process may be a thermally driven desalination process that can compete with the cost of seawater reverse osmosis.

15 GEOTHERMAL ENERGY↗

DOE OSTI2020

Development of metallic nuclear material purification process via simultaneous chlorination and volatilization

Here, a purification process involving simultaneous chlorination and volatilization is reported using aluminum, iron, gallium, and uranium separation from cerium metal as the demonstration system. Anhydrous Cl 2 gas was reacted with the metal after it had been converted to small particles of hydride at temperatures ranging from 523 to 973 K. Each of the impurities should form chlorides with relatively high saturated vapor pressures. The objective of the process was to volatilize these chlorides after first achieving near-complete conversion of the metals to hydride and then chlorides. Complete conversion of hydrides to chlorides could not be achieved using relatively low-grade (99.5%) Cl 2 . High decontamination factors for all of the metal impurities required near complete conversion to chloride. It was concluded that oxygen contamination of the feed gas stream likely limits the conversion to chlorides by forming oxides instead, which then limits the volatilization of contaminants. Uranium was particularly challenging to remove in experiments suspected of having high oxygen contamination in the feed gas stream. After switching to ultra-high purity (99.999%) Cl 2 , complete conversion to chlorides within the measurement error was possible for the entire temperature range studied. Decontamination factors for aluminum, iron, gallium, and uranium were found to have average values of 1.9, 9.8, 14, and 5, respectively, at 973 K. While the process was most extensively studied using a once-through gas flow, recycling unreacted Cl 2 gas succeeded at minimizing waste while still maintaining complete conversion and similar decontamination factors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Improved production and purification of 240Am by deuteron-induced activation of 240Pu target

An optimized method for production of 240Am via the 240Pu(d,2n)240Am reaction is reported. The optimized method produced 7.94 × 108 ± 7% atoms 240Am/mg 240Pu/µA-h. The yield and purity of the products from the optimized method are evaluated in context of the intended application to produce material to measure the cross-section for the 240Am(n,f) reaction. The presented method is also compared with other production methods available in the literature. Keywords—240Am production, deuteron-induced reactions, cross-section, target preparation, post-irradiation purification Abbreviations GEA—Gamma Energy Analysis

Morrison, Erin C.↗

DOE OSTI2021

Production, purification and availability of 211 At: Near term steps towards global access

We report the promising characteristics of the 7.2-h radiohalogen 211 At have long been recognized; including having chemical properties suitable for labeling targeting vectors ranging from small organic molecules to proteins, and the emission of only one α-particle per decay, providing greater control over off-target effects. Unfortunately, the impact of 211 At within the targeted α-particle therapy domain has been constrained by its limited availability. Paradoxically, the most commonly used production method – via the 209 Bi(α,2n) 211 At reaction – utilizes a widely available natural material (bismuth) as the target and straightforward cyclotron irradiation methodology. On the other hand, the most significant impediment to widespread 211 At availability is the need for an accelerator capable of generating ≥28 MeV α-particles with sufficient beam intensities to make clinically relevant levels of 211 At. In this review, current methodologies for the production and purification of 211 At – both by the direct production route noted above and via a 211 Rn generator system – will be discussed. The capabilities of cyclotrons that currently produce 211 At will be summarized and the characteristics of other accelerators that could be utilized for this purpose will be described. Finally, the logistics of networks, both academic and commercial, for facilitating 211 At distribution to locations remote from production sites will be addressed.

60 APPLIED LIFE SCIENCES↗