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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 1,747 records · Page 97
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Morphology of phase-separated VO2 films deposited on TiO2-(001) substrate

Highlights: • Phase separation in VO{sub 2} films at room temperature was studied by TEM. • Tetragonal phase with a zig-zag interface was observed in the neighborhood of the VO{sub 2}/TiO{sub 2} boundary. • The peculiar interface could be explained by the crystallographic relationship between the monoclinic and tetragonal phases. - Abstract: The basic morphology of phase-separated VO{sub 2} films, in which the tetragonal (metallic) phase coexists with the monoclinic (insulating) phase, was studied using transmission electron microscopy. While the phase transformation temperature in an unstrained crystal is approximately 340 K, it was observed that at 298 K, elastic strain (caused by lattice mismatch with the TiO{sub 2}-(001) substrate) stabilized the tetragonal phase near the VO{sub 2}/TiO{sub 2} boundary. The observed zig-zag-shaped interface of the tetragonal phase was explained by the crystallographic orientation relationship between the tetragonal and monoclinic phases. The observations provide valuable information for future applications of VO{sub 2} films.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Easily separable N-doped ZnO microspheres with high photocatalytic activity under visible light

Highlights: • N-doped ZnO microspheres are successfully prepared for environmental photocatalysis. • N doping is responsible for the highly improved photocatalytic activity. • The microspheres are easily separated from the suspension system by sedimentation. - Abstract: Here, two strategies are simultaneously applied to ZnO for easy separation of the photocatalyst particles by forming micron-sized spheres and for extension of the spectral response into the visible region by nitrogen doping. The prepared nitrogen-doped ZnO microspheres show highly improved photocatalytic activity for the degradation of humic acid (HA), a complex refractory organic compound, under visible light. Substitutional and interstitial doping of nitrogen are behind the improved visible light absorption and photocatalytic activity. Using 1 g/L of N-doped ZnO with urea/Zn molar ratio of 3, 95.4% of HA with an initial concentration of 5 mg/L can be degraded within 80 min of visible light irradiation of 122 mW/cm{sup 2}. Under identical experimental conditions, almost complete mineralization of HA is achieved within 12 h. Holes and hydroxyl radicals are mainly responsible for the degradation of HA. Significant reduction of toxicity of the photocatalytically treated HA solution is realized within 9 h.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Supported bicyclic amidine ionic liquids as a potential CO 2 /N 2 separation medium

In this paper, five new room temperature ionic liquids were tested as supported ionic liquid membranes (SILMs) for CO 2 /N 2 separation capability. This series of ionic liquids (ILs) contains bicyclic amidine cations of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) with small alkyl chain substituents. These ILs have been synthesized to examine the effects of cation structure on free volume. Relevant physical and chemical properties have been examined, including CO 2 solubility and viscosity. The relationship between fractional free volume and permeability of gases is explored, with an interesting note on solubility. Each cation was paired with two different anions: bis(trifluoromethanesulfonyl)imide and tetracyanoborate, for further investigation of the cation-anion interaction on SILM permeability and selectivity. Finally, three of these new ILs have exceeded Robeson's upper bound for CO 2 /N 2 gas separations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Carbon molecular sieve membranes for CO 2 /N 2 separations: Evaluating subambient temperature performance

Flue gas CO 2 capture has gained significant attention in recent years to mitigate the environmental impact of greenhouse gases. In spite of excellent performance by polymer membranes, there is still a need for more robust membranes to exceed the polymer upper bound at subambient temperatures, and carbon molecular sieve (CMS) membranes could offer a potential solution. In the present study, as a proof of concept, CMS hollow fiber membranes derived from defect-free 6FDA/BPDA-DAM polymer precursors at a pyrolysis temperature of 550°C were investigated for CO 2 /N 2 separation. Both ambient (35°C) and subambient (-20°C) temperature performance for these CMS membranes have been studied using a combination of pressure decay sorption and permeation techniques. Permeation findings using CO 2 /N 2 (20:80) mixed gas CMS showed CO 2 /N 2 selectivity of ~109 and CO 2 permeance of ~107 GPU at -20°C. Most interestingly, a decrease of only ~33% in CO 2 permeance with a large increase in CO 2 /N 2 selectivity (~4.5 times) was observed for CMS membranes on decreasing temperature from 35°C to -20°C. Gas sorption measurements indicated that the Langmuir hole filling capacity (C’ H ) for CO 2 is very high compared to N 2 at both ambient and subambient temperatures. This trend was attributed to higher sorbed density of CO 2 at saturation in the micropores due to its transition from gas phase to the liquid phase at subambient temperatures. Significant increases in sorption selectivity as well as diffusion selectivity for CO 2 /N 2 going from ambient to subambient temperatures make CMS membranes a possible substitute for polymer membranes for CO 2 /N 2 separation.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Highly permeable carbon molecular sieve membranes for efficient CO 2 /N 2 separation at ambient and subambient temperatures

Carbon molecular sieve (CMS) membranes provide key advantages over current polymer membranes for challenging gas separations. Excellent plasticization resistance and high selectivity with low permeance loss at subambient temperatures also make CMS attractive for potential hybrid post combustion CO 2 capture technology. Here we describe highly permeable ultra-thin skin CMS (ULT-CMS) membranes with CO 2 permeance > 3000 GPU at 35°C and > 2500 GPU at -20°C with 2-3x increase in CO 2 /N 2 selectivity at subambient temperaures . Dual layer polymer precursors fibers comprising Matrimid ® with polyvinylpyrrolidone (PVP), a pore forming polymer, are used to create a substructure support, while 6FDA/BPDA-DAM polymer comprises the thin sheath layer. Two different skin thickness and outer diameter polymer precursor membranes were prepared by varying the spinning parameters to study the effect on CMS performance. Polymer precursor membranes were pretreated with 10% VTMS (vinyltriethoxysilane) to avoid substructure collapse and 0.1% DETDA (3,5-diethyltoluenediamine)/TMC (1,3,5 Bezenetricarbonyltrichloride) hybridization treatment is used to heal nanoscopic defects before pyrolysis. Furthermore, the precursor fibers, pyrolyzed at 550°C, create highly permeable CMS membranes for CO 2 /N 2 separation with high selectivity at ambient and subambient temperaures as noted above.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Highly permeable polyethersulfone substrates with bicontinuous structure for composite membranes in CO 2 /N 2 separation

Substrate morphology has a significant effect on the CO 2 transport performance of a thin-film composite (TFC) membrane. In this study, a new mixed solvent comprising 2-pyrrolidone (2-PD) and 2-methoxyethanol (2-ME) was used to prepare polyethersulfone (PES) substrates with bicontinuous structure by water vapor-induced phase separation, followed by immersion in water as nonsolvent. Here, compared with the commonly used solvent, N-methyl-2-pyrrolidone (NMP), the 2-PD/2-ME mixed solvent is more hydrophilic and can decrease the thermodynamic stability of the casting solution significantly. As a result, the phase separation was induced via the spinodal decomposition mechanism. The open morphology bestowed the optimized substrate with a very high CO 2 permeance of 133,226 ± 3,870 GPU (1 GPU = 10 –6 cm 3 (STP) s –1 cm –2 cmHg –1 = 3.3464 × 10 -9 kg-mol s –1 m –2 Pa –1 ), which was 5 times more permeable than the baseline substrate synthesized with NMP. By using this new substrate, the prepared TFC membrane containing amines showed an increased CO 2 permeance of 908 ± 8 GPU at 57°C, which was 48 GPU higher than that with the baseline substrate. Meanwhile, the CO 2 /N 2 selectivity was retained at 162 ± 4 at 57°C. In addition, the good scalability of the new PES substrate was demonstrated by roll-to-roll fabrication of a 50' long scale-up PES substrate with a width of 21".

2-Pyrrolidone↗
DOE OSTI2017

A rationally designed polysulfide-trapping interface on the polymeric separator for high-energy Li–S batteries

A coating layer consisting of a layer of graphene oxide (GO) inserted in between two layers of multi-walled carbon nanotubes (MWCNT) forms a multifunctional polysulfide-trapping triple-interface on the polymeric separator for lithium–sulfur (Li–S) batteries. The top and bottom highly conductive MWCNT interfaces are able to physically inhibit polysulfide diffusion and effectively reutilize the trapped active material during cycling. The inserted ultrathin GO layer with negatively charged carboxyl groups, on the other hand, electrostatically repels the migrating polysulfide anions. The stacked GO sheets also extensively prolong the migration routes of the polysulfides. Additionally, the “buffer zones” interspersed within the triple-interface accommodate the migrating polysulfides. Thus, the sandwiched separators enable Li–S cells with a high-sulfur-loading (10 mg cm -2 ), high areal capacity (10.9 mA h cm -2 ), and stable cycling ability even though the coating layer is ultra-thin (~17 μm) and light-weight (~0.23 mg cm -2 ).

25 ENERGY STORAGE↗
DOE OSTI2016

Separation of scintillation and Cherenkov lights in linear alkyl benzene

To separate scintillation and Cherenkov lights in water-based liquid scintillator detectors is a desired feature for future neutrino and proton decay experiments. Linear alkyl benzene (LAB) is one important ingredient of a water-based liquid scintillator currently under development. In this paper we report on the separation of scintillation and Cherenkov lights observed in an LAB sample. The rise and decay times of the scintillation light are measured to be (7.7±3.0)ns and (36.6±2.4)ns, respectively, while the full width [–3σ, 3σ] of the Cherenkov light is 12 ns and is dominated by the time resolution of the photomultiplier tubes. Here, the scintillation light yield was measured to be (1.01±0.12)×103photons/MeV .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Electron/hadron separation with the TRD based on GaAs pixel detectors

Transition Radiation Detectors (TRDs) are widely used for particle identification in both high-energy physics and astroparticle physics. They are typically equipped with gaseous detectors. The main limitation of these types of detectors is that TR photons and ionization losses cannot be decoupled, which significantly reduces the particle separation power. Recent advancements in the development of pixel detectors based on GaAs sensors offer a unique opportunity to effectively detect TR photons and separate them from ionization losses. Such detectors represent novel devices that combine precise tracking capabilities with particle identification (PID) properties. The present work is dedicated to an experimental study of particle identification properties of the TRD prototype based on 500 μ m-thick GaAs sensor bonded to a Timepix3 chip. Studies were performed at the CERN SPS and it was shown that at a particle momentum of 20 GeV/c, the probability of misidentifying a hadron as an electron is below 10 −2 for an electron detection efficiency of 98%–99%, and it is 1 . 6⋅10 −4 for electron detection efficiency of 90%. This performance surpasses the electron/hadron rejection power of all known TRDs by an order of magnitude for the same detector length.

GaAs detectors↗
DOE OSTI2016

The Chemistry of Separations Ligand Degradation by Organic Radical Cations

Solvent based extractions of used nuclear fuel use designer ligands in an organic phase extracting ligand complexed metal ions from an acidic aqueous phase. These extractions will be performed in highly radioactive environments, and the radiation chemistry of all these complexants and their diluents will play a major role in determining extraction efficiency, separation factors, and solvent-recycle longevity. Although there has been considerable effort in investigating ligand damage occurring in acidic water radiolysis conditions, only minimal fundamental kinetic and mechanistic data has been reported for the degradation of extraction ligands in the organic phase. Extraction solvent phases typically use normal alkanes such as dodecane, TPH, and kerosene as diluents. The radiolysis of such diluents produce a mixture of radical cations (R •+ ), carbon-centered radicals (R • ), solvated electrons, and molecular products such as hydrogen. Typically, the radical species will preferentially react with the dissolved oxygen present to produce relatively inert peroxyl radicals. This isolates the alkane radical cation species, R •+ as the major radiolytically-induced organic species that can react with, and degrade, extraction agents in this phase. Here we report on our recent studies of organic radical cation reactions with various ligands. Elucidating these parameters, and combining them with the known acidic aqueous phase chemistry, will allow a full, fundamental, understanding of the impact of radiation on solvent extraction based separation processes to be achieved.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Extraction and separation of iridium(Ⅳ) and rhodium(Ⅲ) from hydrochloric acid media by a quaternary ammonium-based hydrophobic eutectic solvent

We report the extraction and separation of iridium(IV) and rhodium(III) from hydrochloric acid solutions by a hydrophobic eutectic solvent composed of tetraheptylammonium chloride and decanoic acid have been studied for the first time. This eutectic solvent selectively extracts iridium(IV) over rhodium(III), the highest separation factor obtained is approximately 20. The effects of the main experimental factors (shaking time, the volume ratio of aqueous to organic phase, hydrochloric acid concentration, and the initial metal concentration in the aqueous phase) on the extraction behavior of iridium(IV) and rhodium(III) have been investigated. Ultraviolet–visible (UV–Vis) spectroscopy was applied to reveal the [IrCl 6 ] 2- complex to be a predominant species attributed to iridium(IV) extraction. To understand the underlying extraction mechanism, the initial iridium(IV) concentration in the aqueous phase has been varied and a corresponding mathematical model has been developed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

An automated micro-separation system for the chromatographic removal of uranium matrix for trace element analysis by ICP-OES

An automated, miniaturized, off-line separation technique is presented here using an Elemental Scientific Inc. microFAST MC system with UTEVA resin to extract the uranium matrix from its trace element impurities in aqueous media. The collected fractions were analyzed for ~30 trace elements using inductively coupled plasma – optical emission spectroscopy. Ten replicate samples were processed with a single column resulting in precision ranging from 3.3% to 6.2% relative standard deviation with regards to the trace element recoveries. Accuracy, with respect to trace element concentrations in the U 3 O 8 Certified Reference Material 124-1, resulted in an average of 13.9% relative deviation while accuracy to the Canadian U3O8 reference material, CUP-2, resulted in an average relative deviation of 8.6%. In conclusion, the total separation time of this automated process was reduced to ~30 min per sample while employing a 0.5 mL UTEVA chromatographic resin bed and 2.5 mg of uranium.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2026

Scalable slot-die coating of phyllosilicate membranes for selective ion separations

Abstract Two-dimensional (2D) materials have recently drawn attention as candidate materials for molecular-scale membrane separations due to their tunable nanoscale interlayer properties. Phyllosilicates, a broad class of naturally abundant 2D clay minerals, offer significant advantages over synthetic 2D materials, including low cost, stability, and environmental compatibility. While these properties make phyllosilicates attractive for industrial-scale nanofiltration applications, phyllosilicate-based membranes have, to date, only been fabricated at the lab scale via vacuum filtration. Scalable fabrication methods are essential to advance the technical maturity of phyllosilicate membranes and bring these promising materials closer to large-scale adoption. Herein, we have successfully scaled up phyllosilicate (vermiculite) membrane fabrication via slot-die coating and roll-to-roll coating of an ethylenediamine–vermiculite (EDAVM) mixture onto nylon. The coated membranes are 1–2 μm $ \unicode{x03BC} \mathrm{m} $ mu m in thickness and exhibit similar structure and performance to vacuum-filtered EDAVM membranes. The membranes also show selectivity for monovalent ions over multivalent ions in binary salt mixtures. This work represents a major step toward scaling up phyllosilicate membranes for industrial ion separation applications such as resource recovery from water.

Booth, Austin [Princeton University]↗
DOE OSTI2023

Quantitative Separation of Unknown Organic–Metal Complexes by Liquid Chromatography–Inductively Coupled Plasma-Mass Spectrometry

Dissolved organic matter (DOM) is widely recognized to control the solubility and reactivity of trace metals in the environment. However, the mechanisms that govern metal-DOM complexation remain elusive, primarily due to the analytical challenge of fractionating and quantifying metal–organic species within the complex mixture of organic compounds that comprise DOM. Here, we describe a quantitative method for fractionation and element-specific detection of organic–metal complexes using liquid chromatography with online inductively coupled plasma mass spectrometry (LC–ICP-MS). The method implements a post-column compensation gradient to stabilize ICP–MS elemental response across the LC solvent gradient, thereby overcoming a major barrier to achieving quantitative accuracy with LC–ICP-MS. With external calibration and internal standard correction, the method yields concentrations of organic–metal complexes that were consistently within 6% of their true values, regardless of the complex’s elution time. We used the method to evaluate the effects of four stationary phases (C18, phenyl, amide, and pentafluoroylphenyl propyl) on the recovery and separation of environmentally relevant trace metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in Suwannee River Fulvic Acid and Suwannee River Natural Organic Matter. The C18, amide, and phenyl phases generally yielded optimal metal recoveries (>75% for all metals except Pb), with the phenyl phase separating polar species to a greater extent than C18 or amide. We also fractionated organic-bound Fe, Cu, and Ni in oxidized and reduced soils, revealing divergent metal-DOM speciation across soil redox environments. Finally, by enabling quantitative fractionation of DOM-bound metals, our method offers a means for advancing a mechanistic understanding of metal–organic complexation throughout the environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Ultra-High Resolution Ion Mobility Separations Utilizing Traveling Waves in a 13 m Serpentine Path Length Structures for Lossless Ion Manipulations Module

We report the development and initial evaluation of a 13-m path length Structures for Lossless Manipulations (SLIM) module for achieving high resolution separations using traveling waves (TW) with ion mobility (IM) spectrometry. The TW SLIM module was fabricated using two mirror-image printed circuit boards with appropriately configured RF, DC and TW electrodes and positioned with a 2.75-mm inter-surface gap. Ions were effective confined between the surfaces by RF-generated pseudopotential fields and moved losslessly through a serpentine path including 44 “U” turns using TWs. The ion mobility resolution was characterized at different pressures, gaps between the SLIM surfaces, TW and RF parameters. After initial optimization the SLIM IM-MS module provided about 5-fold higher resolution separations than present commercially available drift tube or traveling wave IM-MS platforms. Peak capacity and peak generation rates achieved were 246 and 370 s-1, respectively, at a TW speed of 148 m/s. The high resolution achieved in the TW SLIM IM-MS enabled e.g., isomeric sugars (Lacto-N-fucopentaose I and Lacto-N-fucopentaose II) to be baseline resolved, and peptides from a albumin tryptic digest much better resolved than with existing commercial IM-MS platforms. The present work also provides a foundation for the development of much higher resolution SLIM devices based upon both considerably longer path lengths and multi-pass designs.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2016

Retention in porous layer pillar array planar separation platforms

Here, this work presents the retention capabilities and surface area enhancement of highly ordered, high-aspect-ratio, open-platform, two-dimensional (2D) pillar arrays when coated with a thin layer of porous silicon oxide (PSO). Photolithographically prepared pillar arrays were coated with 50–250 nm of PSO via plasma-enhanced chemical vapor deposition and then functionalized with either octadecyltrichlorosilane or n-butyldimethylchlorosilane. Theoretical calculations indicate that a 50 nm layer of PSO increases the surface area of a pillar nearly 120-fold. Retention capabilities were tested by observing capillary-action-driven development under various conditions, as well as by running one-dimensional separations on varying thicknesses of PSO. Increasing the thickness of PSO on an array clearly resulted in greater retention of the analyte(s) in question in both experiments. In culmination, a two-dimensional separation of fluorescently derivatized amines was performed to further demonstrate the capabilities of these fabricated platforms.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Squeezing of Ion Populations and Peaks in Traveling Wave Ion Mobility Separations and Structures for Lossless Ion Manipulations using Compression Ratio Ion Mobility Programming

In this work, we report an approach for spatial and temporal gas phase ion population manipulation, and demonstrate its application for the collapse of the ion distributions in ion mobility (IM) separations into tighter packets providing higher sensitivity measurements in conjunction with mass spectrometry (MS). We do this for ions moving from a conventionally traveling wave (TW)-driven region to a region where the TW is intermittently halted or ‘stuttered’. This approach causes the ion packets spanning a number of TW-created traveling traps (TT) to be redistributed into fewer TT, resulting in spatial compression. The degree of spatial compression is controllable and determined by the ratio of stationary time of the TW in the second region to its moving time. This compression ratio ion mobility programming (CRIMP) approach has been implemented using Structures for Lossless Ion Manipulations (SLIM) in conjunction with MS. CRIMP with the SLIM-MS platform is shown to provide increased peak intensities, reduced peak widths, and improved S/N ratios with MS detection. CRIMP also provides a foundation for extremely long path length and multi-pass IM separations in SLIM providing greatly enhanced IM resolution by reducing the detrimental effects of diffusional peak broadening due to increasing peak widths.

Environmental Molecular Sciences Laboratory↗
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↗