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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Water vapor diffusion membrane development

The phase separator component used as a membrane in the vapor diffusion process (VRD) for the recovery of potable water from urine on manned space missions of extended duration was investigated, with particular emphasis on cation-selective membranes because of their noted mechanical strength, superior resistance to acids, oxidants, and germicides, and their potential resistance to organic foulants. Two of the membranes were tested for 700 hours continuously, and were selected on the basis of criteria deemed important to an effective water reclamation system onboard spacecraft. The samples of urine were successfully processed by removing 93 percent of their water content in 70 hours using the selected membranes. Pretreatment with an acid-oxidant formulation improved product quality. Cation exchange membranes were shown to possess superior mechanical strength and chemical resistance, as compared to cellulosic membranes.

Tan, M. K.↗
DOE OSTI2026

Fabrication of Catalytic Distillation Membranes with Atomic Layer Deposition

The integration of catalysts onto the surface of membranes enables simultaneous physical separation and catalytic transformation of constituents in a feed stream, facilitating improved contaminant removal and fouling mitigation. Distillation membranes are a particularly attractive platform for catalytic membranes because they reject nonvolatile species and exhibit exceptional resistance to oxidative and radical-driven degradation. However, imparting catalytic functionality onto hydrophobic, porous distillation membranes has proven challenging since the membranes used are chemically inert and difficult to modify. Furthermore, catalysts on the membrane surface can decrease hydrophobicity and increase the membrane’s susceptibility to pore wetting and failure. In this work, we create a catalytic distillation membrane by coating a polytetrafluoroethylene membrane surface with titanium dioxide (TiO 2 ) via plasma-assisted atomic layer deposition (ALD). By precisely tuning the ALD parameters, we demonstrate localized growth of TiO 2 near (within approximately 1 μm) the surface of polytetrafluoroethylene membranes, forming a catalytically active interface while preserving the underlying hydrophobic pore structure. Localized growth of TiO 2 is confirmed by electron microscopy and spectroscopy techniques, and membranes coated with 500 cycles of ALD show pressure tolerance up to 12.8 bar and higher than 95% salt rejection in pressure-driven distillation. Photocatalytic activity is demonstrated via the degradation of methylene blue dye under UV irradiation, where increasing TiO2 loading leads to an enhancement in dye degradation. These results establish a general strategy for integrating catalytic functionality into chemically inert, hydrophobic membranes without compromising distillation performance, providing a pathway toward multifunctional membranes that couple advanced oxidation with membrane separation for water treatment.

atomic layer deposition↗
DOE OSTI2023

Carbon-doped metal oxide interfacial nanofilms for ultrafast and precise separation of molecules

Membranes with molecular-sized, high-density nanopores, which are stable under industrially relevant conditions, are needed to decrease energy consumption for separations. Interfacial polymerization has demonstrated its potential for large-scale production of organic membranes, such as polyamide desalination membranes. We report an analogous ultrafast interfacial process to generate inorganic, nanoporous carbon-doped metal oxide (CDTO) nanofilms for precise molecular separation. For a given pore size, these nanofilms have 2 to 10 times higher pore density (assuming the same tortuosity) than reported and commercial organic solvent nanofiltration membranes, yielding ultra-high solvent permeance, even if they are thicker. Owing to exceptional mechanical, chemical, and thermal stabilities, CDTO nanofilms with designable, rigid nanopores exhibited long-term stable and efficient organic separation under harsh conditions.

Science & Technology - Other Topics↗
DOE OSTI2021

CO 2 -selective membranes containing amino acid salts for CO 2 /N 2 separation

In this paper, facilitated transport membranes comprising polyvinylamine (PVAm) as fixed carrier and different amino acid salts (AAS) as mobile carriers were synthesized for post-combustion capture. The AAS carriers were prepared by deprotonating alanine (Ala), lysine (Lys), and proline (Pro) with 2-(1-piperazinyl)ethylamine (PZEA). CO 2 separation performances of the membranes with these AAS carriers were compared, and the AAS effectiveness to facilitate transport of CO 2 was in the order of PZEA-Pro > PZEA-Lys > PZEA-Ala. Here, the membrane comprising 35 wt.% PVAm and 65 wt.% PZEA-Pro at 57 °C rendered a promising CO 2 permeance of 936 GPU and a CO 2 /N 2 mixed gas selectivity of 193. When the PVAm was reduced to 15 wt.%, i.e., its 20 wt.% was replaced by the mobile carrier of PZEA-Sar (sarcosinate), the permeance further improved to 947 GPU with a remarkable CO 2 /N 2 selectivity of 210. Moreover, thermal gravimetric analysis showed a good thermal stability of the membrane, and membrane stability testing also gave stable transport performance. Furthermore, spectroscopic ellipsometry analysis exhibited a uniform membrane selective layer and an excellent agreement on the membrane thickness of ca. 170 nm measured independently by SEM. In addition, the membranes presented in this paper surpassed both the Robeson upper bound and the modified upper bound, indicating a great potential for CO 2 capture.

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

Development of a Supported Emulsion Liquid Membrane System for Propionic Acid Separation in a Microgravity Environment

Perstractive fermentation is a good way to increase the productivity of bioreactors. Using Propionibacteria as the model system, the feasibility of using supported emulsion liquid membrane (SELM) for perstractive fermentation is assessed in this study. Five industrial solvents were considered as the solvent for preparing the SELM. The more polar a solvent is, the higher the partition coefficient. However, toxicity of a solvent also increases with its polarity. CO-1055 (industrial decanol/octanol blend) has the highest partition coefficient toward propionic acid among the solvents that has no molecular toxicity toward Propionibacteria. A preliminary extraction study was conducted using tetradecane as solvent in a hydrophobic hollow fiber contactor. The result confirmed that SELM eliminates the equilibrium limitation of conventional liquid-liquid extraction, and allows the use of a non-toxic solvent with low partition coefficient.

Li, Jin↗
DOE OSTI2022

Separation of rare earth elements using supported membrane solvent extraction

A system and method for the recovery and separation of rare earth elements (REEs) are provided. The system and method include the supported membrane solvent extraction of REEs and the separation of light and heavy REEs that have been recovered from scrap permanent magnets and other electronic waste. In supported membrane solvent extraction, an organic phase consisting of an extractant and an organic solvent is immobilized in the pores of hollow fibers. An aqueous feed solution and a strip solution flow along the shell side and lumen side of the hollow fibers, respectively. The extractant functions as a carrier to selectively transport certain rare earth metal ions from the feed side to the strip side. The rare earth metals are concurrently back extracted in the strip solution, allowing processing to proceed continuously without equilibrium limitations.

Bhave, Ramesh R.↗
DOE OSTI2024

Modeling and Scaling up of Membrane Modules Leveraging Dimensional Analysis

In the current analysis, we study the separation performance using membrane modules through dimensional analysis (DA). We formulate the main process equations to identify relevant dimensionless numbers inherent in the physics. In particular, we identify that the critical step in the separation process is mass transfer through the selective layer. Remarkably, the dimensionless feed flow (DFfeed) emerges as a crucial factor in describing this process. Not only does DFfeed directly appear in the governing equations, but it also holds a physical significance associated with the time scales for the mass transfer across the feed side and through the selective layer. Regarding the output performance variables, we consider the recovery, stage cut, productivity and purity. In this context, we profit from experimental data and CFD simulations to evaluate the separation performance of the modules when varying the input flowrate, the scale of the module, and the CO2 permeance. These datasets enable us to establish correlations between performance metrics and the dimensionless feed flow. Using simple power functions of DFfeed, we obtain R2 coefficients exceeding 0.99, indicating the accuracy of the correlations built in the present work. In the future, we wish to use DA to understand key transport mechanisms, predict and control module performance, and challenge the universality of these findings by testing various gas separations across different membrane modules beyond our case study.

Pedrozo, Hector A.↗
NASA NTRS1989

Electrochemical cell for obtaining oxygen from carbon dioxide atmospheres

For manned missions to Mars to become a reality, an efficient and reliable means of obtaining oxygen from the carbon dioxide-rich atmosphere will be required. Otherwise, the high cost of transporting the oxygen needed to sustain the astronauts will severely restrict the expedition to the martian surface. Recently, the use of electrochemical devices has been explored as a means of obtaining oxygen from the carbon dioxide-rich atmosphere. In these devices, oxygen ions diffuse through solid oxide membranes, thus, separating oxygen from the other gases presented. This phenomenon has only recently been explored as a means of obtaining large quantities of oxygen from toxic atmospheres, although first observed by Walter nernst in 1899. Nernst observed that stabilized zirconia will conduct oxygen ions when an electrical potential is applied across metallic electrodes applied to the ceramic membrane. Diatomic oxygen molecules are dissociated at the positive electrode/electrolyte interface. The oxygen ions enter the ceramic body due to the ion density gradient which is produced by the electrical potential across the electrolytic membrane. Once the ions have diffused through the membrane, they reform diatomic oxygen molecules at the anode. The separation of oxygen from carbon dioxide is achieved by the combination of thermal and electrochemical processes. The thermal decomposition of carbon dioxide (at 1000 C) results in the production of carbon monoxide and oxygen by the reaction.

Hooker, M. W.↗
DOE OSTI2026

Membrane Characterization For Rare Earth Element Separations

The scope of this work is to gain a baseline in membrane characterization for common rare earth elements. Electrochemical processes and techniques for rare earth elements have already been implemented in some cases, but the fundamental behavior has not been thoroughly investigated. With an understanding of the behavior that occurs within the membrane, a better electrochemical device can be developed.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Single-Molecule Tracking Measurements Reveal the Detailed Mechanisms of Molecular Diffusion in Solvent Mixtures under Nanoconfinement

Understanding mass transport mechanisms in nanopores is important for developing advanced materials for chemical separations, chemical sensing, and energy storage. This paper reports a novel imaging platform that is employed for the first time to investigate the detailed diffusion dynamics of single rhodamine B (RhB) dye molecules confined within solution-filled cylindrical anodic aluminum oxide (AAO) nanopores. The imaging platform relies on illumination of horizontally-oriented AAO nanopores in a highly inclined and laminated optical (HILO) light sheet microscopy geometry. The method was used to investigate the translational and orientational dynamics of single rhodamine B (RhB) molecules within horizontally-oriented 5- and 10-nm diameter AAO nanopores filled with water–ethanol mixtures. The established platform enabled the observation of one-dimensional motion along the pore axis involving occasional short- or long-term immobilization at the single-molecule level. Analysis of cumulative squared-displacement distributions revealed fast (5 – 30 µm²/s), intermediate (1 – 5 µm²/s), and slow (< 1 µm²/s) diffusion components. From the effects of mixture composition and pore size on the contributions of these three components, we inferred that the fast, intermediate, and slow components could be assigned to desorption-mediated hopping, crawling, and wiggling motions, respectively. The platform based on the horizontally-oriented AAO nanopores also permitted single-molecule emission polarization measurements that revealed the negligible steric confinement of individual diffusing RhB molecules within the AAO nanopores. The imaging platform based on AAO membranes and HILO microscopy provided a unique means to investigate how solvation-mediated surface interactions and nanoconfinement govern molecular transport in nanoporous environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Data-driven predictions of complex organic mixture permeation in polymer membranes

Membrane-based organic solvent separations are rapidly emerging as a promising class of technologies for enhancing the energy efficiency of existing separation and purification systems. Polymeric membranes have shown promise in the fractionation or splitting of complex mixtures of organic molecules such as crude oil. Determining the separation performance of a polymer membrane when challenged with a complex mixture has thus far occurred in an ad hoc manner, and methods to predict the performance based on mixture composition and polymer chemistry are unavailable. Here, we combine physics-informed machine learning algorithms (ML) and mass transport simulations to create an integrated predictive model for the separation of complex mixtures containing up to 400 components via any arbitrary linear polymer membrane. We experimentally demonstrate the effectiveness of the model by predicting the separation of two crude oils within 6-7% of the measurements. Integration of ML predictors of diffusion and sorption properties of molecules with transport simulators enables for the rapid screening of polymer membranes prior to physical experimentation for the separation of complex liquid mixtures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Simple Bioparticle Filtration Device Based on an Ultralow-Fouling Zwitterionic Polyurethane Membrane for Rapid Large-Volume Separation of Plasma and Viruses from Whole Blood

Plasma separation from whole blood is oftent required as an essential first step when performing blood tests with a viral assay. However, developing a point-of-care plasma extraction device with a large output and high virus recovery remains a significant obstacle to the success of on-site viral load tests. Here, we report a portable, easy-to-use, cost-efficient, membrane-filtration-based plasma separation device that enables rapid large-volume plasma extraction from whole blood, designed for point-of-care virus assays. The plasma separation is realized by a low-fouling zwitterionic polyurethane-modified cellulose acetate (PCBU-CA) membrane. The zwitterionic coating on the cellulose acetate membrane can decrease surface protein adsorption by 60% and increase plasma permeation by 46% compared with a pristine membrane. The PCBU-CA membrane, with its ultralow-fouling properties, enables rapid plasma separation. The device can yield a total of 1.33 mL plasma from 10 mL whole blood in 10 min. The extracted plasma is cell-free and exhibits a low hemoglobin level. In addition, our device demonstrated a 57.8% T7 phage recovery in the separated plasma. The results of real-time polymerase chain reaction analysis confirmed that the nucleic acid amplification curve of the plasma extracted by our device is comparable to that obtained by centrifugation. With its high plasma yield and good phage recovery, our plasma separation device provides an excellent replacement for traditional plasma separation protocols for point-of-care virus assays and a broad spectrum of clinical tests.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Surface engineering of polymeric membranes with metal oxides for improved fouling resistance and superior oil-water separation

Rapid industrial growth has increased the need for efficient membranes to separate oil-water emulsions. Polyvinylidene fluoride (PVDF) membranes, although widely used due to their chemical inertness and favorable mechanical properties, suffer from fouling due to their intrinsic hydrophobicity. Modifying these membranes after fabrication offers a practical solution as it easily fits into existing large-scale manufacturing processes. Atomic layer deposition (ALD), an atomically-precise vapor phase surface modification technique, can create ultrathin metal oxide layers that greatly improve membrane hydrophilicity without significantly affecting the original pore size. However, PVDF's lack of reactive chemical moieties makes ALD challenging. Here, in this study, we present a simple alkali treatment that greatly enhances ALD nucleation and growth on PVDF membranes. This treatment imparts exceptional oil-water emulsion separation capabilities and antifouling behavior in PVDF membranes after just a few ALD cycles, surpassing the performance of PVDF membranes coated with hundreds of ALD cycles. This dramatic reduction in the number of ALD cycles required could enable cost-effective modification of commercial PVDF membranes at scale using spatial, roll-to-roll ALD. These modified membranes outperform reported modified PVDF membranes, with >99 % permeance recovery and <1 % irreversible loss of permeance and >98 % oil rejection from oil-water emulsions over 100 h continuous operation, making them promising for advanced water purification technologies.

Atomic layer deposition↗
DOE OSTI2024

Engineered selective biotoxin‐binding hydrogels for toxin sequestration

The development of synthetic selective membranes that separate materials of similar sizes, charges, and/or polarities remains a difficult challenge, and looking towards biology provides inspiration for new designs. In this work, a series of cholera toxin binding peptides (CTBPs) are identified, spanning a range of binding inhibitions, and integrated into chemically cross-linked cholera toxin binding gels (CTBGs) via thiol-Michael polycondensation reactions. All gels demonstrate rheological profiles consistent with elastic solids. The CTBGs are probed via small-angle neutron scattering and exhibit a correlation length, ξ, smaller than most proteins (1.3–2.5 nm). Thus, an effective entropic mesh is formed to block non-targeted proteins. However, the CTBGs have a dynamic mesh size, Ξ, that is larger than cholera toxin (CT) to allow the transport of target proteins. The CTBGs with the highest binding inhibitions both show high selectivity and permeation of CT, rejecting all other tested proteins. In total, two new highly selective CTBGs are synthesized and validated for use in cholera toxin remediation. Together, this platform demonstrates the wide applicability of selectively-diffusive materials for difficult separations.

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

Rapid macrovoid characterization in membranes prepared via nonsolvent-induced phase separation: A comparison between 2D and 3D techniques

Optimizing the performance of asymmetric membranes prepared via nonsolvent-induced phase separation (NIPS) requires a quantitative understanding of how processing variables influence membrane morphology. Presently, the most useful structural quantification techniques require 3D visualization of the membrane structure and are best suited for studies seeking detailed information on small datasets. This study proposes and validates a rapid and accurate technique for quantifying macroporosity (i.e., D m ), a simple descriptor of sublayer macrovoid content in asymmetric membranes D m . values measured from segmented cross-sectional imaging performed via X-ray computed tomography (XCT) and scanning electron microscopy (SEM) are presented and compared for three asymmetric membranes prepared from commercial polymers. Importantly, analyses of 3D XCT membrane reconstructions reveal that D m is described by a single, centralized mean, which demonstrates that macrovoid content is spatially homogenous. Thus, D m can be approximated from limited sampling of the 2D cross-sectional membrane structure via SEM. A proposed 2D SEM sampling method provides D m estimates within ±6% of corresponding 3D XCT values with 30 independent measurements for the three membranes. Further sensitivity is achieved using complementary descriptors such as macrovoid count density (i.e., C m ). This technique is thus a useful tool for characterizing macroporosity from a broad selection of membrane samples.

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

In Situ Growth of Crystalline and Polymer-Incorporated Amorphous ZIFs in Polybenzimidazole Achieving Hierarchical Nanostructures for Carbon Capture

We report mixed matrix materials (MMMs) hold great potential for membrane gas separations by merging nanofillers with unique nanostructures and polymers with excellent processability. In situ growth of the nanofillers is adapted to mitigate interfacial incompatibility to avoid the selectivity loss. Surprisingly, functional polymers have not been exploited to co-grow the nanofillers for membrane applications. Herein, in situ synergistic growth of crystalline zeolite imidazole framework-8 (ZIF-8) in polybenzimidazole (PBI), creating highly porous structures with high gas permeability, is demonstrated. More importantly, PBI contains benzimidazole groups (similar to the precursor for ZIF-8, i.e., 2-methylimidazole) and induces the formation of amorphous ZIFs, enhancing interfacial compatibility and creating highly size-discriminating bottlenecks. For instance, the formation of 15 mass% ZIF-8 in PBI improves H- 2 permeability and H- 2 /CO 2 selectivity by approximate to 100% at 35 degrees C, breaking the permeability/selectivity tradeoff. This work unveils a new platform of MMMs comprising functional polymer-incorporated amorphous ZIFs with hierarchical nanostructures for various applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

Amine-Containing Membranes with Functionalized Multi-Walled Carbon Nanotubes for CO2/H2 Separation

Amine-containing mixed-matrix membranes incorporated with amino-functionalized multi-walled carbon nanotubes (AF-MWNTs) were synthesized for CO2/H2 separation based on the facilitated transport mechanism. AF-MWNTs were chosen primarily as the mechanical reinforcing filler to enhance the membrane stability. At 107 °C and 0.2-MPa feed pressure, the membrane incorporated with 10 wt.% AF-MWNTs showed a CO2 permeability of 3196 Barrers and a CO2/H2 selectivity of 205. At the higher feed pressure of 1.5 MPa, owing to the carrier saturation phenomenon, the same membrane exhibited reduced transport performance with a CO2 permeability of 776 Barrers and a CO2/H2 selectivity of 31. These separation performances at both the low and high feed pressures were well above the theoretical upper bound. Furthermore, the incorporation of 10 wt.% AF-MWNTs led to a significant improvement on membrane stability. The transport performance and selective layer thickness of this membrane maintained for 100 h, which suggested that the incorporation of AF-MWNTs improved the resistance to membrane compaction upon a high feed pressure. Therefore, this work is considered as one of the crucial steps to enable the application of facilitated transport membranes to high-pressure gas processing such as syngas purification.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Carbon molecular-sieve membranes developed from a Tröger’s base polymer and possessing superior gas-separation performance

Carbon molecular-sieve membranes possess tremendous practical advantages over unary polymer membranes by providing high gas-separation performance levels, coupled with excellent mechanical and chemical stability. Improving their overall effectiveness greatly expands the competitiveness of this class of membranes. In the present study, carbon membranes are fabricated from a Tröger’s base polymer as the precursor. Further, by optimizing the carbonization conditions, the gas-separation performance of the resultant membranes are significantly enhanced. Under optimized conditions, a H 2 permeability of up to 1135 Barrer is achieved, with a corresponding H 2 /CH 4 selectivity of 1170 and a CO 2 /CH 4 selectivity of 238. While increasing the operating temperature slightly reduces the selectivity, it still remains in the high-separation region. Overall, the measured separation performance levels for H 2 -related separations, i.e., H 2 /CH 4 , H 2 /N 2 and H 2 /CO 2 , all substantially exceed the Robeson upper bound. Moreover, the CO 2 /CH 4 separation efficacy also lies above the 2019 upper bound, indicating that the carbon membranes developed in the present work are versatile and promising for many different gas-separation applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗