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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Mixtures of octanol and an ionic liquid: Structure and transport

Ionic liquids (ILs) with long alkyl substituents are amphiphilic, which leads to a bicontinuous liquid structure. The strongly interacting anionic and cationic head groups form a long range charge network, with the hydrocarbon tails forming a nonpolar domain. Such nonpolar domains have been shown to dissolve a variety of neutral organic solvents. In mixtures of ILs with solvents the neutral organic molecules residing in the nonpolar domains experience different environments and friction from the charged cations and anions. Thus, the neutral molecules diffuse much faster than predicted by hydrodynamic scaling using the average viscosity of the mixture. Here, we report studies on the structure and transport properties of mixtures of 1-octanol with the IL trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide (P 6,6,6,14 + /NTf 2 – ). The majority of the atom fraction in the P 6,6,6,14 + cation comprises four hydrocarbon substituents. The unique amphiphilic nature of ILs with the P 6,6,6,14 + cation makes 1-octanol fully miscible with the IL at ambient temperatures. X-ray scattering experiments show that the IL structure persists in the mixtures for 1-octanol mole fractions as large as x oct = 0.90. The self-diffusion coefficients of the three molecular species in the mixtures were measured by NMR experiments. The self-diffusion of the P 6,6,6,14 + cation is well described by the Stokes–Einstein equation, while the diffusivity of the NTf 2 – anion is slightly lower than the hydrodynamic prediction. The measured diffusivities of octanol in these mixtures are 1.3–4 times higher than the hydrodynamic predictions.

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

Continuous liquid-phase synthesis of nickel phosphide nanoparticles in a helically coiled tube reactor

The continuous liquid phase synthesis of nickel phosphide (Ni 2 P) nanoparticles was studied in a helically coiled tube (HCT) reactor both in single-phase and two-phase slug flows. The reactants were nickel acetylacetonate and tri-n-octylphosphine (TOP) in a 1-octadecane solvent. For the single-phase mode, various parameters such as reaction temperature, residence time, TOP concentration, and P/Ni ratio were studied. It was found that lower temperatures of 320 and 340 °C resulted in the formation of mixed Ni 12 P 5 and Ni 2 P phases, while a higher temperature of 360 °C gave mostly Ni 2 P, with particle sizes increasing from 28 to 42 nm. Upon varying the contact time between 88 and 340 s at 360 °C, a likely sequence of reaction involved an amorphous phase that was transformed in parallel to Ni, Ni 12 P 5 , and Ni 2 P. When the flow in the HCT was changed to a two-phase slug flow by using N 2 to split the continuous liquid phase into small liquid columns, the product was nearly 100% Ni 2 P and the particle size was as small as 3–4 nm. This was attributed to the enhanced mass transfer in the small liquid columns of the slug flow that led to higher reaction rates. Finally, it is highlighted that the HCT operated in a slug flow is an efficient and continuous method for the fabrication of nanoparticles.

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

Compromise of Personal Protective Clothing from Liquid Exposure

Following critiques of multiple personal contamination events from entries into the Oak Ridge National Laboratory’s Spallation Neutron Source transfer bay, it was considered that the most likely causes for contamination were personal protective clothing doffing errors or that moisture (sweat) allowed contamination to wick through the protective clothing. To pursue this issue, radiological protection staff looked more closely, however, at the specific area of the clothing where contamination was highest; under enhanced lighting and photochromic manipulation, there appeared to have been some type of moisture in the area. Recognizing the possibility that moisture may have allowed for migration of contamination through the clothing, further experiments were undertaken to determine under which conditions this transport might have occurred. The objective for this work was to identify the susceptibility of different types of personal protective clothing to various liquids encountered in the workplace.Method: Several tests were performed to determine if perspiration had enabled migration of contamination, and to identify what other liquids might have affected contamination transport. Two layers of personal protective clothing were subjected to static conditions and dynamic conditions, to include active rubbing of the materials while wet. Food dye added to each of the liquids tested enabled visual indications of liquid breakthrough. Additional tests were conducted to see if solid contamination could be transported through the materials along with the liquids. As a result, it was found that all but one type of non-rubberized personal protective clothing in use at Oak Ridge National Laboratory were permanently compromised to some extent by the solvents used for decontamination. It was determined that most common cleaning agents immediately and permanently destroyed the hydrophobic nature of several of the splash-resistant protective clothing materials, allowing for radioactive contamination to penetrate through the material to the worker. Work around wet surfaces or performing wet decontamination will only be performed in protective clothing known to prevent transport of the wetting agent.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2021

A rapid thioacidolysis method for biomass lignin composition and tricin analysis

Abstract Background Biomass composition varies from plant to plant and greatly affects biomass utilization. Lignin is a heterogeneous phenolic polymer derived mainly from p -coumaryl, coniferyl, and sinapyl alcohols and makes up to 10–25% of lignocellulosic biomass. Recently, tricin, an O -methylated flavone, was identified as a lignin monomer in many grass species. Tricin may function as a nucleation site for lignification and is advocated as a novel target for lignin engineering to reduce lignin content and improve biomass digestibility in grasses. Thioacidolysis is an analytical method that can be adapted to analyze both lignin monomeric composition and tricin content in the lignin polymer. However, the original thioacidolysis procedure is complex, laborious, and time consuming, making it difficult to be adopted for large-scale screening in biomass research. In this study, a modified, rapid higher throughput thioacidolysis method was developed. Results In combination with gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–mass spectrometry (LC–MS), the modified thioacidolysis method can be used to simultaneously characterize the lignin composition and tricin content using 2–5 mg of dry samples. The modified method eliminates the solvent extraction and drastically improves the throughput; 80 samples can be processed in one day per person. Our results indicate that there is no significant difference in the determination of lignin S/G ratio and tricin content between the original and modified methods. Conclusions A modified thioacidolysis protocol was established. The results demonstrate that the modified method can be used for rapid, high-throughput, and reliable lignin composition and tricin content analyses for screening transgenic plants for cell wall modifications or in large-scale genome-wide association studies (GWAS).

09 BIOMASS FUELS↗
DOE OSTI2020

Melting of Magnesium Borohydride under High Hydrogen Pressure: Thermodynamic Stability and Effects of Nanoconfinement

The thermodynamic stability and melting point of magnesium borohydride were probed under hydrogen pressures up to 1000 bar (100 MPa) and temperatures up to 400 °C. At 400 °C, Mg(BH4)2 was found to be chemically stable between 700 and 1000 bar H2, whereas under 350 bar H2 or lower pressures, the bulk material partially decomposed into MgH2 and MgB12H12. The melting point of solvent-free Mg(BH4)2 was estimated to be 367-375 °C, which was above previously reported values by 40-90 °C. Our results indicated that a high hydrogen backpressure is needed to prevent the decomposition of Mg(BH4)2 before measuring the melting point and that molten Mg(BH4)2 can exist as a stable liquid phase between 367 and 400 °C under hydrogen overpressures of 700 bar or above. The occurrence of a pure molten Mg(BH4)2 phase enabled efficient melt-infiltration of Mg(BH4)2 into the pores of porous templated carbons (CMK-3 and CMK-8) and graphene aerogels. Both transmission electron microscopy and small-angle X-ray scattering confirmed efficient incorporation of the borohydride into the carbon pores. The Mg(BH4)2@carbon samples exhibited comparable hydrogen capacities to bulk Mg(BH4)2 upon desorption up to 390 °C based on the mass of the active component; the onset of hydrogen release was reduced by 15-25 °C compared to the bulk. Importantly, melt-infiltration under hydrogen pressure was shown to be an efficient way to introduce metal borohydrides into the pores of carbon-based materials, helping to prevent particle agglomeration and formation of stable closo-polyborate byproducts.

White, James L.↗
DOE OSTI2020

Amidoxime-functionalized materials and their use in extracting metal ions from liquid solutions

A method of producing a functionalized material that extracts metal ions from solution, the method comprising: (i) providing a precursor material having nitrile groups appended to its surface; and (ii) reacting said nitrile groups with hydroxylamine or a derivative thereof in the presence of a polar aprotic solvent at a temperature of 60-80° C. for at least 1 hour, to convert at least a portion of said nitrile groups to amidoxime and imide dioxime groups, followed by reaction with a base capable of hydrolyzing any remaining nitrile groups to carboxylic acid groups; wherein said functionalized material has a higher uranium absorption capacity than a functionalized material produced under same conditions except that the nitrile groups are reacted with hydroxylamine in only a protic solvent. The invention is also directed to functionalized materials produced by the above-described method, and methods for using the functionalized material for extracting metal ions from metal-containing solutions.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Amidoxime-functionalized materials and their use in extracting metal ions from liquid solutions

A method of producing a functionalized material that extracts metal ions from solution, the method comprising: (i) providing a precursor material having nitrile groups appended to its surface; and (ii) reacting said nitrile groups with hydroxylamine or a derivative thereof in the presence of a polar aprotic solvent at a temperature of 60-80° C. for at least 1 hour, to convert at least a portion of said nitrile groups to amidoxime and imide dioxime groups, followed by reaction with a base capable of hydrolyzing any remaining nitrile groups to carboxylic acid groups; wherein said functionalized material has a higher uranium absorption capacity than a functionalized material produced under same conditions except that the nitrile groups are reacted with hydroxylamine in only a protic solvent. The invention is also directed to functionalized materials produced by the above-described method, and methods for using the functionalized material for extracting metal ions from metal-containing solutions.

Janke, Christopher J.↗
DOE OSTI2025

Balancing solvation: stabilizing lithium metal batteries via optimized cosolvents for ionic-liquid electrolytes

In this study, we examined three cosolvents with distinct solvation capabilities for ionic-liquid electrolytes based on 1-methyl-1-propyl pyrrolidinium bis(fluorosulfonyl)imide (Py13FSI). We demonstrate that 1,1,1-trifluoro-2-(2-(2-(2,2,2-trifluoroethoxy)ethoxy)ethoxy)ethane (FDG) notably enhances the cycle life of Py13FSI-based electrolytes, outperforming 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropylether (TTE) and diglyme (DG). Electrochemical and surface analyses showed that this improvement could be attributed to the formation of a favorable cathode interphase, promoting efficient Li+ transport with reduced overpotential. Spectroscopic techniques (FTIR, Raman, and NMR spectroscopy) and molecular dynamics simulations revealed that cosolvents with varying solvation abilities can influence the solvation structures in Py13FSI-based electrolytes. The mild solvating strength and lithium stability of FDG are key contributors to its effectiveness. Conversely, DG, a strong solvating solvent, destabilized the Py13FSI-DG electrolyte at the lithium metal anode, while TTE, a non-solvating solvent, failed to enhance lithium transport or form a stable cathode interphase. Our findings highlight that balanced solvation exerted by the cosolvents is critical for forming a stable electrolyte–cathode interface, potentially through FSI decomposition. This study offers valuable insights into the development of durable ionic-liquid electrolytes, emphasizing the importance of selecting cosolvents with optimal solvation properties.

Li, Xinlin [Argonne National Laboratory (ANL), Arg↗
DOE OSTI2024

Rotating cylinder electrode in reactive CO 2 capture: Identifying active C species via transport, VLE models and kinetics

Here, this article explores technical challenges and potential methodologies for understanding electrochemical Reactive CO 2 Capture (RCC) mechanisms. RCC offers potential energy cost advantages by directly converting captured CO 2 into fuels and chemicals, unlike traditional carbon capture and utilization (CCU) processes that require sequential capture, concentration, and compression. However, direct conversion of captured CO 2 introduces complexity due to additional equilibrium buffer reactions, making it challenging to identify active species for reduction in electrochemical studies. This article discusses methods to integrate transport, thermodynamics, and kinetics concepts to identify active carbon sources in RCC. Vapor‐Liquid Equilibrium (VLE) and transport models are validated against experimental results obtained in a gastight rotating cylinder electrode reactor and are shown as useful tools for studying RCC in heterogeneous electrocatalysts across different capture agents, solvents, and temperatures. This article establishes an experimental framework for advancing research in electrochemical RCC.

Electrocatalysis↗
DOE OSTI2022

Molecular simulation of glycerol-derived triether podands for lithium ion solvation

Solvate ionic liquids (ILs) are promising candidates for several applications due to their stability, high coulombic efficiency, and low volatility. In this work, we investigate the solvation of lithium-bistriflimide by different glycerol-derived triether solvents, using molecular dynamics simulations. Very strong interactions between Li + and the solvent oxygen sites are found, leading to significant conformational changes in the solvent. Here, by comparing the conformation of the neat solvents with their IL mixtures at different concentrations and temperatures, we find that the presence of Li + induces a distinct crown-like structure in the solvent molecules. The Li + cations and the surrounding solvent form a podand complex, which is stable even at elevated temperatures. These glycerol-derived solvents exhibit distinct interactions with Li + cations which may be exploited in electrolytic applications or lithium recovery processes.

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

Direct Air Capture-Compatible Azolate and Amino Acid Ionic Liquids for Electrochemical CO 2 Reduction to CO on a Silver Cathode

Direct air capture (DAC) compatible ionic liquids (ILs) are attractive for integrating CO 2 capture and conversion due to their high CO 2 solubility at low partial pressures, tunable chemisorption mechanisms, low volatility, and wide electrochemical windows. However, very few ILs have high CO 2 uptake at DAC conditions (420 ppm CO 2 ), and even fewer have been evaluated for chemical compatibility and mechanistic continuity for combined capture and electrochemical CO 2 reduction (eCO 2 RR). We demonstrate that two representative DAC-capable ILs, [P 4444 ][Val] (amino acid-based) and [P 66614 ][5-Me-Imd] (azolate-based), exhibit favorable electrochemical reduction behavior. CO and H 2 were the dominant gas-phase products by GC, while 1 H and 13 C NMR confirmed negligible liquid-phase HCOOH. Chronoamperometry at moderate applied potentials (−2.0 to −2.5 V vs Ag/AgCl) in a two-compartment H-cell with a Ag coated carbon paper as the working electrode yielded steady-state current densities of ∼10 mA cm −2 with CO FE of 96% for [P 4444 ][Val] and 95% for [P 66614 ][5-Me-Imd], highlighting the role of viscosity and chemically absorbed CO 2 -IL species to provide highly selective CO formation while suppressing H 2 evolution.

amino acid ionic liquid↗
NASA NTRS1996

Electrorheological Fluids: Aerospace Applications

Electrorheological fluids (ERF) are an intriguing class of non-Newtonian industrial fluids. They consist of fine dielectric particles suspended in liquids of low dielectric constants. The objectives of this research were to select a particulate system such that: (1) its density can be varied to match that of the selected liquid, and (2) the dielectric constant of the particles and the liquids should be such that the critical fields needed for asymptotic increase in viscosity are less than or equal to 10 KV/cm. Synthetic Zeolite particles were selected as the solute/suspensions. Octoil oil was selected as the solvent. The results are summarized here.

Parmar, D. S.↗
DOE OSTI2022

Size-tunable silver nanoparticle synthesis in glycerol driven by a low-pressure nonthermal plasma

Silver nanoparticles (NPs) are extensively used in electronic components, chemical sensors, and disinfection applications, in which many of their properties depend on particle size. However, control over silver NP size and morphology still remains a challenge for many synthesis techniques. Here, in this work, we demonstrate the surfactant-free synthesis of silver NPs using a low-pressure inductively coupled nonthermal argon plasma. Continuously forming droplets of silver nitrate (AgNO 3 ) precursor dissolved in glycerol are exposed to the plasma, with the droplet residence time being determined by the precursor flow rate. Glycerol has rarely been studied in plasma-liquid interactions but shows favorable properties for controlled NP synthesis at low pressure. We show that the droplet residence time and plasma power have strong influence on NP properties, and that improved size control and particle monodispersity can be achieved by pulsed power operation. Silver NPs had mean diameters of 20 nm with geometric standard deviations of 1.6 under continuous wave operation, which decreased to 6 nm mean and 1.3 geometric standard deviation for pulsed power operation at 100 Hz and 20% duty cycle. We propose that solvated electrons from the plasma and vacuum ultraviolet (VUV) radiation induced electrons produced in glycerol are the main reducing agents of Ag + , the precursor for NPs, while no significant change of chemical composition of the glycerol solvent was detected.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Spatially Mapping the CO 2 Alkaline Sorbent Diffuse Microenvironment Using Operando Raman Spectroscopy

When designing a chemical process, the local balance of transport and kinetics, collectively referred to as the diffuse microenvironment, plays a critical role in performance but is difficult to directly observe. This work demonstrates a method of two-dimensional spatial chemical mapping of the diffuse microenvironment in the context of alkali metal hydroxide direct air capture of carbon dioxide using a custom operando gas-absorption flow cell along with confocal Raman spectroscopy. Notably, we observe the concentration boundary layer near the gas–liquid interface and elucidate the interplay of carbonate and bicarbonate ions within it while inferring local hydroxide depletion through continuum modeling. These first of their kind observations provide a technique to compare the performance of direct air capture solvents based on diffuse microenvironment dynamics while also providing metrics important for air contactor design such as boundary layer thickness. Overall, this work showcases a new experimental platform to study interfacial diffuse microenvironments in and outside of the field of direct air capture of carbon dioxide.

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

147 Nd Quantification Using HSCCC-Purified Samples

Quantifying the fission product 147 Nd in nuclear debris samples is an important component of post-detonation nuclear forensics. The most accurate quantifications are obtained when Nd is purified from all other fission products, actinides, activation products, and environmental matrix contained within the debris. In this study, a recently developed method for Nd purification was tested, purifying 147 Nd from solutions of mixed fission products using high-speed counter-current chromatography (HSCCC). Importantly, the new method allowed for faster elution of Nd from the column as compared with established high performance liquid chromatography (HPLC) methods, and resulted in accurate/precise 147 Nd quantification by gamma-ray spectrometry. While the up-front equipment costs associated with HSCCC may be higher, its operational costs are on par with those of HPLC (solvents, extractants, power). Gas-flow proportional beta decay counting revealed contamination from the nearest neighbor lanthanide 143 Pr (a gamma-silent radioisotope) in the HSCCC-purified samples, but the activity contribution from 147 Nd could still be quantified. Remarkably consistent elution profiles were observed for the HSCCC method, spanning rare earth element (REE) loadings of more than 10 orders of magnitude (tracer to mmol quantities). In conclusion, the reliability and speed of the new method suggest utility for the rapid separation and quantification of 147 Nd in unknown samples.

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

Competitive Adsorption of Lubricant Base Oil and Ionic Liquid Additives at Air/Liquid and Solid/Liquid Interfaces

Oil-soluble ionic liquids (ILs) have been proved as effective additives in lubricant oils through tribological experiments and post-test analytical analyses. Here, surface structures of lubricant base oil, oil-soluble ILs, and their mixtures at the air/liquid and solid/liquid interfaces have been studied using sum frequency generation (SFG) vibrational spectroscopy. At the air/base oil and air/IL interfaces, the alkyl chains of the studied compounds were shown to be conformationally disordered and their terminal methyl groups point outward at the liquid surface. The base oil dominates the air/(base oil + IL) interface due to its higher surface excess propensity and larger bulk concentration. At the solid (silica) surface, ILs adopt a structure with their charged headgroups in contact with the silica surface, while their alkyl chains are more conformationally ordered or packed compared to the air/IL interface. At the interface between silica and (base oil + IL) mixtures, ILs also preferentially adsorb to the silica surface with their layer structures somewhat different from those of ILs alone. These results showed that ILs can adsorb onto the solid surface even before tribological contacts are made. The insights obtained from this SFG study provide a better understanding of the role of ionic liquids in lubrication.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Effects of dilution in ionic liquid supercapacitors

Room-temperature ionic liquids (RTILs) are synthetic electrolytes that have a large electrochemical stability window, making them attractive candidates for electric double-layer capacitor (EDLC) applications. Due to their high viscosities and low ionic conductivities, RTILs are often diluted with organic solvent for practical use. Here, we study the effects of dilution on the performance of RTIL EDLCs using a simple mean-field model. We find that dilution diminishes the unfavorable hysteresis that results from a spontaneous surface charge separation (SSCS). As a result, the RTIL concentration can be used to modulate the proximity to the SSCS transition, and maximize capacitance. The interplay between the concentration and the correlation strength gives rise to complex zero-potential phase behavior, including a tricritical point and a λ-line, very similar to the Blume–Capel dilute Ising model. Additionally, electrodes that are solvophilic aid in the prevention of SSCS by drawing solvent molecules to the electrode and displacing ions. Solvophilic electrodes give rise to a phase transition at finite potential where the surface charge rapidly increases with a small increase in potential, leading to a substantial increase in capacitance and energy storage.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗