Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Aqueous solution”

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 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Radiation-Induced Plutonium Redox Chemistry

Plutonium plays a key role in global actinide research and nuclear fuel cycle technologies, and yet, our fundamental understanding of its inherent radiation-induced chemical behavior is limited. These radiation-induced processes cannot simply be switched off, as they are as fundamentally inherent to plutonium as the impact of relativistic effects on its f-electrons. In less chemically complex actinide systems, such as aqueous solutions of neptunium and americium, , radiolysis products play a significant role in the redox cycling of their oxidation states. However, plutonium's multiple, coexisting, and chemically active oxidation states, which comprise of bare ions and dioxo cations, provide additional redox pathways that complicate radiation-induced processes. Oxidation state control is critical for the manipulation of plutonium, especially in used nuclear fuel reprocessing technologies, where oxidation specific states are successfully extracted, and others rejected. Consequently, mechanistically understanding the behavior of plutonium’s multiple oxidation states in the presence of intense ionizing radiation fields is essential for predicting the behavior of this element under multiple conditions that support the development and innovation of nuclear fuel cycle technologies. Here, we present recent advances in our understanding of plutonium radiation chemistry, including the first-ever multiscale model for predicting gamma radiation-induced plutonium redox chemistry, and new chemical kinetics for the reaction of plutonium and its complexes of tributyl phosphate (TBP), N,N-di-(2-ethylhexyl)butyramide (DEHBA), and N,N-di-(2-ethylhexyl)isobutyramide (DEHiBA) with transients radiolysis products, a measured using electron pulse radiolysis.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Speckle contrast from the split-and-delay unit with seeded X-ray pulses of the MID instrument at European XFEL

We report on the coherence properties and characteristics of the split- and-delay unit at the Materials Imaging and Dynamics instrument of the European XFEL under seeded-beam conditions. Our investigation focuses on the speckle contrast extracted from the scattering patterns from static scatterers and pulse splitting characteristics. Seeded-beam operation enabled a high throughput of the split-and-delay unit. We highlight the invaluable potential of the split-and-delay unit for experimental investigations for enhancing our understanding of ultrafast phenomena in molecular liquids, such as water and aqueous solutions.

Fuoss, Paul↗
DOE OSTI2024

Battery cell with safety layer

A battery cell comprising a composite water-responsive safety layer and/or composite water- and pH-responsive safety layer to protect against tissue damage and/or electrolysis, when the battery cell is exposed to aqueous solution or tissue, is provided. The composite water-responsive safety layer and/or composite water- and pH-responsive safety layer is adapted to change from a non-electronically conducting state to an electronically conducting state.

Pozin, Michael↗
DOE OSTI2024

Sum-of-Fractions Method

Sum-of-fractions is a method intended to make sure a subcritical margin for aqueous solutions and slurries of fissionable isotopes exists. The method indicates that a system is subcritical if the sum of the ratios of the mass of each isotope (in a mixture) to its individual minimum subcritical mass limit is less than or equal to one. Historically, the basis of the sum-of-fractions has been derived from allowances given in the American National Standards Institute (ANSI)/ American Nuclear Society (ANS)-8.15-1981. However, the allowance was removed in ANSI/ANS-8.15-2014 due to a lack of technical basis. A methodology was developed to assess the validity of using the sum-of-fractions for water- or polyethylene-moderated systems for the following nuclides: 232U, 233U, 234U, 235U, 237Np, 236Pu, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, 241Am, 242mAm, 243Am, 242Cm, 243Cm, 244Cm, 245Cm, 246Cm, 247Cm, 249Cf, and 251Cf. The methodology uses available benchmark data for mixtures of 233U, 235U, and 239Pu to establish the calculational margin, and a mass limit reduction to establish the margin of subcriticality. Water- or polyethylene-moderated and -reflected mixtures containing the nuclides are evaluated with the code system, SCALE 6.2.4. Including the calculational margin, subcritical mass limits for each nuclide were computed for optimally water- or polyethylene-moderated and fully reflected systems. These masses were used to create nuclide mixtures in which the sum of the mass to subcritical mass limit ratios is one. The various nuclide mixtures were modeled over a range of moderation and demonstrate the keff does not exceed the calculational margin. For additional assurance of subcriticality, a significant mass reduction is applied to each computed minimum critical mass of the nuclides without adequate benchmark data consistent with the method in ANSI/ANS-8.15-2014.

criticality safety, Actinide↗
DOE OSTI2023

Novel method of recycling perovskite solar cells using iodide solutions

A novel recycling method utilizing aqueous iodide solutions has shown promise at selectively dissolving lead perovskite and preserving the glass substrate of lead perovskite solar cells (PSCs). Perovskite compounds are notorious for degrading upon contact with moisture into lead iodide which can be capitalized upon for recycling. When iodide ions reach a critical concentration in aqueous solutions, the solubility of lead iodide begins to rapidly increase as several complex ions are formed. Iodide solutions selectively interact with the perovskite material which dissolves from the edge inwards, allowing for exfoliation of the back contact and retention of the glass substrate and electron transport layer. PbI 2 solubility studies using KI, HI, and NH 4 I were conducted to determine an effective iodide source to develop a scalable recycling process. Further, retaining the coated glass substrate intact preserves the possibility to manufacture new solar cells from the same materials, by also omitting the use of organic solvents the costs as well as the human and environmental hazards of recycling PSCs can be minimized.

14 SOLAR ENERGY↗
DOE OSTI2022

Electrical Conductivities and Association Constants in Dilute Aqueous NdCl 3 Solutions from 298 to 523 K along an Isobar of 25 MPa

Here, electrical measurements were performed in dilute aqueous NdCl 3 solutions from 298 to 523 K along the 25 MPa isobar to obtain limiting conductivities and association constants. The specific conductivity data were estimated using a continuous flow cell and a Markov Chain Monte Carlo (MCMC) correction algorithm. The limiting conductivities for the salts in water were derived by regressing the mean spherical approximation model and speciation analyses based on the MCMC algorithm and the deep earth water model. The limiting conductivities derived from the experimental data were correlated using the Zimmerman-Arcis-Tremaine correlation and agreed well with a predictive correlation proposed by Smolyakov, Anderko, and Lencka. Only the first association constant between neodymium and chloride could be derived at low temperatures (<373 K) due to the apparent large statistical uncertainty of the second association constant. Above 373 K, both association constants could be derived and show a reasonable agreement with Migdisov and Williams-Jones and Gammons et al.

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

Evolution of Metastable Phases During Mg Metal Corrosion: An In Situ Cryogenic X-ray Photoelectron Spectroscopy Study

Magnesium and its alloys are potential structural materials candidates for a wide variety of applications due to their high strength-to-weight ratio. However, ductility and poor corrosion resistance under ambient environmental conditions are the bottleneck for industrial deployment. Designing passivation layers and/or corrosion resistant alloys requires fundamental understanding of the corrosion process. The traditional ex-situ spectroscopic measurements of polycrystalline metal surface with ubiquitous surface impurities and grain boundaries only provided an indistinct view of the corrosion process. To clearly distinguish the mechanism and sequence of corrosion process, we employed in-situ cryo-based x-ray photoelectron spectroscopy (XPS) measurements on Mg single crystal surface exposed to aqueous salt solution. Clean Mg (0001) surfaces were exposed to pure D2O and NaCl aqueous solution (5 wt% NaCl+95 wt% D2O). The interfacial reactions were studied using multimodal analysis including XPS, x-ray diffraction (XRD) and scanning electron microscopy (SEM). In contrast to previous studies, our experiments demonstrated the formation of magnesium chloride hydroxide hydrate during aqueous salt corrosion processes. Evidence of metastable ClO* radicals were also found during the initial aqueous salt solution exposure.

Shutthanandan, Vaithiyalingam↗
DOE OSTI2023

Effect of isopropanol cosolvent on the rheology and spinnability of aqueous polyacrylic acid solutions

Abstract We investigate the effect of alcohol fraction (isopropanol, IPA) in a binary water‐alcohol solvent mixture on the shear and extensional rheological properties, as well as the role of viscoelasticity on fiber formation of poly(acrylic acid) (PAA) in electrospinning. Comparison of the scaling of both specific viscosities η sp and extensional relaxation times λ E of PAA in water–IPA mixtures, showed stronger scaling compared to salt‐free aqueous polyelectrolyte solutions, except for the η sp in the unentangled regime displaying a polyelectrolyte‐like scaling η sp ~ c 0.5 for all IPA%. Such deviation suggested IPA induces association/aggregation of PAA. However, the trends between η sp and λ E magnitudes as a function of IPA% differ for concentrations compared in the entangled regime. The η sp as well as their elastic moduli exhibit a maximum, whereas λ E increases monotonically with IPA%, suggesting a complex interplay of various interactions are dictating their structure in water‐IPA mixtures, affecting their shear and extensional response differently. Electrospinning experiments showed increasing IPA% reduces the onset of both beaded and uniform fibers. Analysis using dimensionless numbers indicated the enhancement of their elasticity by IPA, and the consequent stabilizing effect on their jets/filaments against break‐up during electrospinning, plays a role in the improvement of their fiber formation.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Polymer Layer-Accelerated CO 2 Absorption in Aqueous Amino Acid Solutions

Direct air capture (DAC) of CO 2 via solvent-based absorption is considered a promising negative-emission technology. However, the low concentration of CO 2 in the air and slow transport into the solvent make DAC notoriously challenging to implement without costly investments. In this study, we explore the fundamental role that the bulk and surface properties of CO 2 -permeable polymer membranes play in enhancing the efficiency of the solution sorption process in passive DAC of CO 2 . This work leverages various spectroscopic and computational studies to demonstrate that a hybrid system, comprising a reusable CO 2 -permeable polymer layer placed atop an aqueous amino acid (AA) solution, can outperform a pure aqueous AA system by 2-fold. Here we show how the enhanced solubility of CO 2 in the polymer layer can improve the transport of CO 2 into the aqueous phase, while the chemistry of the polymer can control the interfacial barrier for CO 2 permeation and the interfacial concentration of reactive AAs. The derived knowledge of the material properties achieved here can aid in the design of DAC systems with improved performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2001

Methanol Uptake by Low Temperature Aqueous Sulfuric Acid Solutions

The global methanol budget is currently unbalanced, with source terms significantly larger than the sinks terms. To evaluate possible losses of gaseous methanol to sulfate aerosols, the solubility and reactivity of methanol in aqueous sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosols is under investigation. Methanol will partition into sulfate aerosols according to its Henry's law solubility. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H*, for cold (196 - 220 K) solutions ranging between 45 and 70 wt % H2SO4. We have found that methanol solubility ranges from approx. 10(exp 5) - 10(exp 7) M/atm for UT/LS conditions. Solubility increases with decreasing temperature and with increasing sulfuric acid content. Although methanol is slightly more soluble than are acetone and formaldehyde, current data indicate that uptake by clean aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These solubility measurements include uptake due to physical solvation and any rapid equilibria which are established in solution. Reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H is not significant over our experimental time scale for solutions below 80 wt % H2SO4. To confirm this directly, results obtained using a complementary equilibrium measurement technique will also be presented.

Iraci, L. T.↗
DOE OSTI2021

Effects of anionic and nonionic surfactants on the dispersion and stability of nanoSiO2 in aqueous and cement pore solutions

It has been well recognized that the benefits and effectiveness of nanoparticles in cement-based materials could not be maximized if these are not well dispersed. To address this issue, in this study, different anionic (SDS and PCE) and nonionic surfactants (Tweens and Tritons) were used to disperse nanosilica (NS) in aqueous solution and cement pore solution. The results show that the dispersibility of NS in cement pore solution was improved, and the compressive strength of the cement-NS pastes increased linearly with critical micelle concentration (CMC) of nonionic surfactants. Among all surfactants studied, Triton X-405 led the paste to the highest increase in strength (33% at 1-day and 41% at 3-days) since it had the highest CMC. TEM and EDS analysis evidenced that this strength increase might be attributed to the nucleation of outer product CSH gel and its densification with calcite nanocrystals, attributed to Triton X-405 addition.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Deciphering the Solvation Structure of Aqueous ZnCl 2 Solutions from X-ray Absorption Spectra Using the Interpretable Graph Neural Network

Machine learning (ML) provides powerful pathways for predicting spectroscopic observables from atomic structures, but its broader impact depends on making model predictions interpretable in terms of physical and chemical principles. Here, we introduce a physics-guided graph neural network (GNN) model that predicts Zn K-edge X-ray spectroscopy (XAS) spectra of aqueous ZnCl 2 solutions. Training data are generated from ab initio XAS calculations on molecular dynamics snapshots obtained using a machine learning interatomic potential. The GNN reproduces experimental spectra across concentrations from dilute (<0.1 m) to highly concentrated (30 m, “water-in-salt”) regimes and scales efficiently to large, disordered liquid systems beyond the reach of conventional ab initio approaches. Gradient-based attribution analysis reveals that the model learns physically meaningful structure-spectrum relationships. Ligand-specific attributions reflect orbital hybridization patterns and the origin of the excitations derived from the density functional theory. Bond-length attributions recover spectral shifts consistent with multiple-scattering theory. Finally, this work bridges data-driven prediction with electronic-structure theory, establishing a general paradigm for interpretable ML that links atomic structure, electronic structure, and spectroscopic observables.

25 ENERGY STORAGE↗
DOE OSTI2022

Tangent gradient concentration material for battery, digital gradient concentration material for battery

The invention provides a cathode active material having a discrete change in concentrations of a first base region and a second pulse region. Also provided is a method for preparing a cathode active material, the method having the steps: supplying chelating agent, aqueous basic solution and a first aqueous metal salt solution to a reactor to create a base region; supplying a second aqueous metal-salt solution to a reactor to form a pulse region, wherein the second aqueous metal-salt solution is intermittently or continuously added during or after the creation of the base region; thermally treating the base region and the pulse region to create active metal precursors; mixing the precursors with lithium salt to produce a mixture; and thermally treating the mixture.

Shin, YoungHo↗
DOE OSTI2021

Local molecular environment drives speciation and reactivity of ion complexes in concentrated salt solution

The speciation and reactivity of aqueous salt solutions are important for a wide variety of applications. However, application of this information is inhibited by broad disagreement about composition, mechanisms, and structure in concentrated solutions especially. Here, neutron diffraction with isotopic substitution measurements on aqueous zinc chloride solutions are used to calibrate molecular dynamics simulations that include effective electronic polarization. This allows us to probe the origin of speciation and reactivity of zinc chloride-water ion complexes, ZnCl x (H 2 O) y 2-x (x ≤ 4 and y ≤ 6), by comparing the reactivity of species in concentrated (4.5 m) and dilute (0.01 m) conditions. Within the concentrated solution, it is found that the extended solvation environment is dominated by solvent-separated ion complexes whose presence increases the free energy of activation for interconversion of species while simultaneously enhancing their thermodynamic stability. This concentration-dependent reactivity and stability suggests that other reactions, such as the nucleation of solid phases, will also be affected.

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

An organogel library for solution NMR analysis of nanoparticle suspensions in non-aqueous samples

Surface contrast solution NMR methods (scNMR) are emerging as powerful tools to investigate the adsorption of small molecule ligands to the surface of nanoparticles (NP), returning fundamental insight into the kinetics and thermodynamics of sorption, as well as structural information on the adsorbed species. A prerequisite for the acquisition of high quality solution NMR data is the preparation of homogeneous and stable samples that return consistent NMR spectra and allow extensive signal averaging. Unfortunately, this condition does not apply to NMR samples containing NPs that often show a tendency to sediment and accumulate at the bottom of the NMR tube over the course of the experiment. We have recently shown that preparing NMR samples in an agarose gel matrix inhibits sedimentation and allows the characterization of small molecule-NP interactions by scNMR. Unfortunately, as the agarose gel only forms in aqueous solution, this sample preparation method cannot be used to stabilize NP suspensions in a non-aqueous environment. In this work, we introduce a library of 48 organogels, based on low molecular-mass organic gelators (LMOGs), to prepare NMR samples of small molecule/NP systems in a wide range of organic solvents. In addition, we present a simple method that takes advantage of 1H transverse relaxation (1H-R2) measurements to screen the library and identify the best gelator to characterize the small molecule-NP interaction of interest in the solvent of choice. We expect the results of this study will enable the preparation of homogeneous and stable samples of NPs in non-aqueous environments, therefore dramatically increasing the applicability of scNMR to the characterization of heterogeneous interactions and to the investigation of the role played by solvent molecules in regulating the kinetics and thermodynamics of sorption.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2005

Uptake of Hypobromous Acid (HOBr) by Aqueous Sulfuric Acid Solutions: Low-Temperature Solubility and Reaction

Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45 - 70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H* = 10(exp 4) - 10(exp 7) mol/L/atm. H* is inversely dependent on temperature, with Delta H = -46.2 kJ/mol and Delta S = -106.2 J/mol/K for 55 - 70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into aqueous 45 wt% H2SO4, the solubility can be described by log H* = 3665/T - 10.63. For 55 - 70 wt% H2SO4, log H* = 2412/T - 5.55. At temperatures colder than approx. 213 K, the solubility of HOBr in 45 wt% H2SO4 is noticeably larger than in 70 wt% H2SO4. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Our measurements indicate chemical reaction of HOBr upon uptake into aqueous sulfuric acid in the presence of other brominated gases followed by evolution of gaseous products including Br2O and Br2, particularly at 70 wt% H2SO4.

Iraci, Laura T.↗
DOE OSTI2023

Method for carbon dioxide capture and sequestration using alkaline industrial wastes

A method of sequestering gaseous carbon dioxide in which an oxide is carbonated by contacting it with a first aqueous carbonate solution to convert a portion of the oxide into a carbonate, which precipitates from solution. By converting the oxide to a solid carbonate, the CO 2 from the first carbonate solution is sequestered into the precipitate. At the same time, an aqueous hydroxide solution is formed. The aqueous hydroxide solution is contacted with gaseous carbon dioxide which sequesters the gaseous CO 2 into a second aqueous carbonate solution. The second solution so generated is then recycled back into the process and used to convert the oxide into the precipitated carbonate.

Wang, Bu↗
DOE OSTI2026

Role of washing solvents in defining the magnetic performance of Sm 2 Fe 17 N 3 obtained by reduction diffusion

Calciothermic reduction-diffusion (RD) is one of the leading synthesis methods for Sm 2 Fe 17 N 3 (SmFeN), but sintering of such RD-derived powders is hampered by oxidation and CaO byproducts. Here, we systematically evaluate how post-synthesis washing solvents govern powder chemistry and magnetic performance. RD-synthesized SmFeN powder was washed with several aqueous and non-aqueous solvents using identical washing protocols. This was followed by an assessment of both the as-washed powder as well as after annealing at 425 °C. Phase content was quantified by synchrotron PXRD and Rietveld refinement and SEM/EDS. The oxygen content of the powders was determined via inert gas fusion and the magnetization by DC magnetometry. While all aqueous-based solutions were able to remove CaO, the non-aqueous solutions were only effective with extended washing times. Prior to annealing, the crystalline phases and magnetic properties of the as-washed powders were largely the same regardless of washing solvent. However, differences emerge after annealing, where water-based washing markedly lowers the coercivity (H c ~3.8-4.3 kOe). In contrast, non-aqueous NH 4 Cl-methanol washing protocols were more effective in preserving coercivity (H c ~4.9-5.9 kOe). We attribute this to lower oxygen content in the non-aqueous samples (~9,400 ppm v ~6,400 ppm, respectively) which in turn reduced the formation of α-Fe during annealing. These results highlight the importance of solvent choice in washing RD-synthesized SmFeN and demonstrate that non-aqueous protocols, which better limit oxidation, outperform aqueous solvents despite the need for longer washing times.

36 MATERIALS SCIENCE↗