Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “PURIFICATION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Recovery of high specific activity molybdenum-99 from accelerator-induced fission on low-enriched uranium for technetium-99m generators

Abstract A new process was developed to recover high specific activity (no carrier added) 99 Mo from electron-accelerator irradiated U 3 O 8 or uranyl sulfate targets. The process leverages a novel solvent extraction scheme to recover Mo using di(2-ethylhexyl) phosphoric acid following uranium and transuranics removal with tri- n -butyl phosphate. An anion-exchange concentration column step provides a final purification, generating pure 99 Mo intended for making 99 Mo/ 99m Tc generators. The process was demonstrated with irradiated uranium targets resulting in more than 95% 99 Mo recovery and without presence of fission products or actinides in the product.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Natural and enriched Cr target development for production of Manganese-52

52 Mn is a promising PET radiometal with a half-life of 5.6 days and an average positron energy of 242 keV. Typically, chromium of natural isotope abundance is used as a target material to produce this isotope through the nat/52 Cr(p,n) 52 Mn reaction. While natural Cr is a suitable target material, higher purity 52 Mn could be produced by transitioning to enriched 52 Cr targets to prevent the co-production of long-lived 54 Mn (t 1/2 = 312 day). Unfortunately, 52 Cr targets are not cost-effective without recycling processes in place, therefore, this work aims to explore routes to prepare Cr targets that could be recycled. Natural Cr foils, metal powder pellets, enriched chromium-52 oxide and Cr(III) electroplated targets were investigated in this work. Each of these cyclotron targets were irradiated, and the produced 52 Mn was purified, when possible, using a semi-automated system. An improved purification by solid-phase anion exchange from ethanol-HCl mixtures resulted in recoveries of 94.5 ± 2.2% of 52 Mn. The most promising target configuration to produce a recyclable target was electroplated Cr(III). This work presents several pathways to optimize enriched Cr targets for the production of high purity 52 Mn.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Production and radiochemistry of the in vivo PET generator 140 Nd/ 140 Pr as an imaging surrogate for F-block therapeutic radionuclides

Theranostics, a combined approach of diagnostics and therapeutics, often employs F-block therapeutic radionuclides including 225 Ac, 177 Lu, and 161 Tb. While there is a lack of F-block PET imaging radionuclides, the in vivo PET generator pair 140 Nd/ 140 Pr can act as a theranostic imaging counterpart to the F-block therapeutic radionuclides. In this study, we explored the production and separation of high purity 140 Nd via the 141 Pr(p,2n) 140 Nd reaction route. Monoisotopic 141 Pr targets irradiated with 20 MeV protons for 10 min with 10 µA beam current yielded 21.45 ± 0.82 MBq (580 ± 22 µCi) of 140 Nd. A two-step separation method was developed for the purification of 140 Nd from the 141 Pr target material. Recoveries of 27.4 ± 2.1% 140Nd were obtained upon separation with < 20 ppb of 141 Pr target material in the final product. Radiolabeling of Macropa and DOTA chelators with 140 Nd resulted in [ 140 Nd]Nd-Macropa with a molar activity of 74.0 MBq/µmol (2.0 mCi/µmol) and [ 140 Nd]Nd-DOTA with a molar activity of 70.3 MBq/µmol (1.9 mCi/µmol). An imaging study with a phantom indicated the PET spatial resolution of 140 Nd/ 140 Pr was distinguishable down to 2.4 mm. This study sets the stage for the 140 Nd/ 140 Pr in vivo PET generator to be explored in radiopharmaceutical applications.

F-block↗
DOE OSTI2020

Sustainable lead management in halide perovskite solar cells

Despite the rapid development of perovskite solar cells (PSCs) toward commercialization, the toxic lead (Pb) ions in PSCs pose a potential threat to the environment, health and safety. Managing Pb via recycling represents a promising approach to mitigating its toxicity. However, managing Pb from commonly used organic solvents has been challenging due to the lack of suitable Pb adsorbents. Here, we report a new adsorbent for both separation and recovery of Pb from PSC pollutants. The synthesized iron-incorporated hydroxyapatite possesses a strongly negatively charged surface that improves electrostatic interaction through surface-charge delocalization, thus leading to enhanced Pb adsorption. Finally, we demonstrate the feasibility of a complete Pb management process, including the purification of Pb-containing non-aqueous solvents below 15 parts per 10 9 , a level compliant with the standards of the US Environmental Protection Agency, as well as recycling of 99.97% of Pb ions by forming lead iodide.

14 SOLAR ENERGY↗
DOE OSTI2025

A multi-omic characterization of the physiological responses to salt stress in Scenedesmus obliquus UTEX393

Scenedesmus obliquus UTEX393 is a promising microalgal candidate for sustainable biomanufacturing but its limited halotolerance hinders large-scale cultivation in saline environments. To investigate the molecular basis of salt stress responses, we conducted a comprehensive multi-omic analysis integrating genomics, transcriptomics, proteomics, lipidomics, metabolomics, and DNA affinity purification sequencing (DAP-seq). An improved nuclear genome assembly and annotation yielded 19,017 gene models and a 97% BUSCO completeness score, enabling construction of a genome-scale metabolic model. Comparing 15 ppt salinity stress to 5 ppt control, growth and productivity were significantly reduced, accompanied by widespread transcriptomic and proteomic changes. Transcriptomic analysis revealed downregulation of photosynthetic machinery and energy conservation genes, and upregulation of stress-responsive elements such as expansins, flavodoxins, and osmoprotectants. Lipidomic profiling showed accumulation of triacylglycerols (TAGs) and degradation of galactosyl lipids, consistent with a shift toward lipid biosynthesis to mitigate redox imbalance. Depletion of key polar metabolites and branched-chain amino acids suggested a rerouting of central carbon metabolism under stress. DAP-seq identified key transcription factors, including LHY1 and SPL12, that target central metabolic enzymes involved in redox balancing, such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and malate dehydrogenase (MDH). These findings establish a regulatory-metabolic framework linking redox stress to lipid accumulation and reveal potential engineering targets to enhance salt tolerance. Overall, the multi-omic analysis supports the “overflow” hypothesis, where impaired photosynthesis results in excess reducing equivalents being diverted into TAG synthesis and highlights transcriptional regulators as candidates for improving algal robustness in brackish environments.

09 BIOMASS FUELS↗
DOE OSTI2023

Ion solvation as a predictor of lanthanide adsorption structures and energetics in alumina nanopores

Adsorption reactions at solid-water interfaces define elemental fate and transport and enable contaminant clean-up, water purification, and chemical separations. For nanoparticles and nanopores, nanoconfinement may lead to unexpected and hard-to-predict products and energetics of adsorption, compared to analogous unconfined surfaces. Here we use X-ray absorption fine structure spectroscopy and operando flow microcalorimetry to determine nanoconfinement effects on the energetics and local coordination environment of trivalent lanthanides adsorbed on Al 2 O 3 surfaces. We show that the nanoconfinement effects on adsorption become more pronounced as the hydration free energy, ΔG hydr , of a lanthanide decreases. Neodymium (Nd 3+ ) has the least exothermic ΔG hydr (-3336 kJ·mol -1 ) and forms mostly outer-sphere complexes on unconfined Al 2 O 3 surfaces but shifts to inner-sphere complexes within the 4 nm Al 2 O 3 pores. Lutetium (Lu 3+ ) has the most exothermic ΔG hydr (-3589 kJ·mol -1 ) and forms inner-sphere adsorption complexes regardless of whether Al 2 O 3 surfaces are nanoconfined. Importantly, the energetics of adsorption is exothermic in nanopores only, and becomes endothermic with increasing surface coverage. Changes to the energetics and products of adsorption in nanopores are ion-specific, even within chemically similar trivalent lanthanide series, and can be predicted by considering the hydration energies of adsorbing ions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Femtosecond laser pulse driven melting in gold nanorod aqueous colloidal suspension: Identification of a transition from stretched to exponential kinetics

Many potential industrial, medical, and environmental applications of metal nanorods rely on the physics and resultant kinetics and dynamics of the interaction of these particles with light. We report a surprising kinetics transition in the global melting of femtosecond laser-driven gold nanorod aqueous colloidal suspension. At low laser intensity, the melting exhibits a stretched exponential kinetics, which abruptly transforms into a compressed exponential kinetics when the laser intensity is raised. It is found the relative formation and reduction rate of intermediate shapes play a key role in the transition. Supported by both molecular dynamics simulations and a kinetic model, the behavior is traced back to the persistent heterogeneous nature of the shape dependence of the energy uptake, dissipation and melting of individual nanoparticles. These results could have significant implications for various applications such as water purification and electrolytes for energy storage that involve heat transport between metal nanorod ensembles and surrounding solvents.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

Solid-state optical refrigeration to sub-100 Kelvin regime

We report that since the first demonstration of net cooling twenty years ago, optical refrigeration of solids has progressed to outperform all other solid-state cooling processes. It has become the first and only solid-state refrigerator capable of reaching cryogenic temperatures, and now the first solid-state cooling below 100 K. Such substantial progress required a multi-disciplinary approach of pump laser absorption enhancement, material characterization and purification, and thermal management. Here we present the culmination of two decades of progress, the record cooling to ≈91K from room temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Anthropogenic plutonium-244 in the environment: Insights into plutonium’s longest-lived isotope

Owing to the rich history of heavy element production in the unique high flux reactors that operated at the Savannah River Site, USA (SRS) decades ago, trace quantities of plutonium with highly unique isotopic characteristics still persist today in the SRS terrestrial environment. Development of an effective sampling, processing, and analysis strategy enables detailed monitoring of the SRS environment, revealing plutonium isotopic compositions, e.g., 244 Pu, that reflect the unique legacy of plutonium production at SRS. This work describes the first long-term investigation of anthropogenic 244 Pu occurrence in the environment. Environmental samples, consisting of collected foot borne debris, were taken at SRS over an eleven year period, from 2003 to 2014. Separation and purification of trace plutonium was carried out followed by three stage thermal ionization mass spectrometry (3STIMS) measurements for plutonium isotopic content and isotopic ratios. Furthermore, significant 244 Pu was measured in all of the years sampled with the highest amount observed in 2003. The 244 Pu content, in femtograms (fg = 10 –15 g) per gram, ranged from 0.31 fg/g to 44 fg/g in years 2006 and 2003 respectively. In all years, the 244 Pu/ 239 Pu atom ratios were significantly higher than global fallout, ranging from 0.003 to 0.698 in years 2014 and 2003 respectively.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2017

Structural reorganization of the fungal endoplasmic reticulum upon induction of mycotoxin biosynthesis

Eukaryotic cells routinely compartmentalize metabolic pathways to particular organelles for biosynthetic purposes. Relatively few studies have addressed the cellular localization of pathways for secondary metabolites synthesis. In this study, the phytopathogenic fungus Fusarium graminearum reorganized its endoplasmic reticulum (ER) when triggered to produce mycotoxins, both in vitro and in planta. Fluorescence tagged biosynthetic proteins were found to co-localize with the modified ER as confirmed by co-fluorescence and co-purification with known ER proteins. Microscopy, cell sorting, and proteomics were applied in this FICUS collaborative effort.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

CHAPTER 9. Bijels the Easy Way

Spinodal decomposition is not the only way to make a bijel. Indeed, while spinodal decomposition produces structures with a potentially useful morphology, it can be challenging to make bijels using this method and the resulting systems can be hard to process and manipulate. Furthermore, exploiting the functional properties of the assembled particle monolayer is extremely challenging. Here, we show how the assembly of nanoparticle surfactants at the liquid–liquid interface can be used to kinetically trap liquids into a wealth of complex structures without using spinodal decomposition. We apply liquid three-dimensional printing and moulding methods, along with patterned substrates with controllable wetting properties, to build all-liquid devices with applications in chemical synthesis, separation, and purification. The functional properties of the assembled nanomaterials can be exploited to produce interfacially structured liquids that are plasmonically and magnetically responsive. Finally, we conclude by arguing that, while the field shows great promise, efforts need to be made to translate liquid bicontinuous systems out of the laboratory and into meaningful, real-world applications, as well applications in more ‘exotic’ disciplines, such as synthetic biology.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Exploiting the Physicochemical Properties of Dendritic Polymers for Environmental and Biological Applications

In this Perspective we first examine the rich physicochemical properties of dendritic polymers for hosting cations, anions, and polyaromatic hydrocarbons. We then extrapolate these conceptual discussions to the use of dendritic polymers for humic acid antifouling, oil dispersion, copper sensing, and fullerenol remediation. In addition, we review the state-of-the-art of dendrimer research and elaborate on their 10 implications for water purification, environmental remediation, nanomedicine, and energy harvesting.

Bhattacharya, Priyanka↗
DOE OSTI2013

235 U– 231 Pa age dating of uranium materials for nuclear forensic investigations

Here, age dating of nuclear material can provide insight into source and suspected use in nuclear forensic investigations. We report here a method for the determination of the date of most recent chemical purification for uranium materials using the 235 U- 231 Pa chronometer. Protactinium is separated from uranium and neptunium matrices using anion exchange resin, followed by sorption of Pa to an SiO 2 medium. The concentration of 231 Pa is measured by isotope dilution mass spectrometry using 233 Pa spikes prepared from an aliquot of 237 Np and calibrated in-house using the rock standard Table Mountain Latite and the uranium isotopic standard U100. Combined uncertainties of age dates using this method are 1.5 to 3.5 %, an improvement over alpha spectrometry measurement methods. Model ages of five uranium standard reference materials are presented; all standards have concordant 235 U- 231 Pa and 234 U- 230 Th model ages.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2014

A Facile Approach Using MgCl2 to Formulate High Performance Mg2+ Electrolytes for Rechargeable Mg Batteries

Rechargeable Mg batteries have been regarded as a viable battery technology for grid scale energy storage and transportation applications. However, the limited performance of Mg2+ electrolytes has been a primary technical hurdle to develop high energy density rechargeable Mg batteries. In this study, MgCl2 is demonstrated as a non-nucleophilic and cheap Mg2+ source in combining with Al Lewis acids (AlCl3, AlPh3 and AlEtCl2) to formulate a series of Mg2+ electrolytes characteristic of high oxidation stability (up to 3.4 V vs Mg), sulfur compatibility and electrochemical reversibility (up to 100% coulombic efficiency). Three electrolyte systems (MgCl2-AlCl3, MgCl2-AlPh3, and MgCl2-AlEtCl2) were prepared free of purification and fully characterized by multinuclear NMR (27Al{1H} and 25Mg{1H}) spectroscopies, single crystal X-ray diffraction, and electrochemical analysis. The reaction mechanism of MgCl2 and the Al Lewis acids in THF is discussed to highlight the formation of the electrochemically active [(µ-Cl)3Mg2(THF)6]+ monocation in these electrolytes. We are grateful for the financial support from the Pacific Northwest National Laboratory (PNNL)-Laboratory Directed Research and Development (LDRD) program for developing magnesium battery technology. The XRD and SEM data were collected at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL. PNNL is a multiprogram laboratory operated by Battelle Memorial Institute for the Department of Energy under Contract DE-AC05-76RL01830.

electrolytes↗
DOE OSTI2015

An efficient and practical synthesis of [2- 11 C]indole via superfast nucleophilic [ 11 C]cyanation and RANEY® Nickel catalyzed reductive cyclization

We developed a rapid method for the synthesis of carbon-11 radiolabeled indole using a sub-nanomolar quantity of no-carrier-added [ 11 C]cyanide as radio-precursor. Based upon a reported synthesis of 2-(2-nitrophenyl)acetonitrile (2), a highly reactive substrate 2-nitrobenzyl bromide (1) was evaluated for nucleophilic [ 11 C]cyanation. Additionally, related reaction conditions were explored with the goal of obtaining of highly reactive 2-(2-nitrophenyl)-[1- 11 C]acetonitrile ([ 11 C]-2) while inhibiting its rapid conversion to 2,3-bis(2-nitrophenyl)-[1- 11 C]propanenitrile ([ 11 C]-3). Next, a Raney Nickel catalyzed reductive cyclization method was utilized for synthesizing the desired [2- 11 C]indole with hydrazinium monoformate as the active reducing agent. Extensive and iterative screening of basicity, temperature and stoichiometry was required to overcome the large stoichiometry bias that favored 2-nitrobenzylbromide (1) over [ 11 C]cyanide, which both caused further alkylation of the desired nitrile and poisoned the Raney Nickel catalyst. The result is an efficient two-step, streamlined method to reliably synthesize [2- 11 C]indole with an entire radiochemical yield of 21 ± 2.2% (n = 5, ranging from 18 – 24%). The radiochemical purity of the final product was > 98% and specific activity was 176 ± 24.8 GBq/μmol (n = 5, ranging from 141 – 204 GBq/μmol). The total radiosynthesis time including product purification by semi-preparative HPLC was 50 – 55 min from end of cyclotron bombardment.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Techno-economic analysis of a conceptual biofuel production process from bioethylene produced by photosynthetic recombinant cyanobacteria

Ethylene is a petrochemical produced in large volumes worldwide. It serves as a building block for a wide variety of plastics, textiles, and chemicals, and can be converted into liquid transportation fuels. There is great interest in the development of technologies that produce ethylene from renewable resources, such as biologically derived CO 2 and biomass. One of the metabolic pathways used by microbes to produce ethylene is via an ethylene-forming enzyme (EFE). By expressing a bacterial EFE gene in a cyanobacterium, ethylene has been produced through photosynthetic carbon fixation. Here, we present a conceptual design and techno-economic analysis of a process of biofuel production based on the upgradation of ethylene generated by the recombinant cyanobacterium. This analysis focuses on potential near-term to long-term cost projections for the integrated process of renewable fuels derived from ethylene. The cost projections are important in showing the potential of this technology and determining research thrusts needed to reach target goals. The base case for this analysis is a midterm projection using tubular photobioreactors for cyanobacterial growth and ethylene production, cryogenic distillation for ethylene separation and purification, a two-step Ziegler oligomerization process with subsequent hydrotreatment and upgradation for fuel production, and a wastewater treatment process that utilizes anaerobic digestion of cyanobacterial biomass. The minimum fuel selling price (MFSP) for the midterm projection is 15.07 per gallon gasoline equivalent (GGE). Near-term and long-term projections are 28.66 per GGE and 5.36 per GGE, respectively. Single- and multi-point sensitivity analyses are conducted to determine the relative effect that chosen variables could have on the overall costs. This analysis identifies several key variables for improving the overall process economics and outlines strategies to guide future research directions. Finally, the productivity of ethylene has the largest effect on cost and is calculated based on a number of variables that are incorporated into this cost model (i.e., quantum requirement, photon transmission efficiency, and the percent of energy going to either ethylene or cyanobacterial biomass production).

09 BIOMASS FUELS↗