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At least 271 records · Page 15

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DOE OSTI2025

Irreversible thermodynamics of curved lipid membranes. II. Permeability and osmosis

We present a theory that combines the framework of irreversible thermodynamics with modified integral theorems to model arbitrarily curved and deforming membranes immersed in bulk fluid solutions. We study the coupling between the mechanics and permeability of a viscous and elastically bendable membrane, and a multicomponent bulk fluid solution. An equation for the internal entropy production for irreversibilities at the membrane is derived, determining the generalized thermodynamic forces and fluxes, from which we identify the deviatoric stress as a novel driving force for permeability. A complete set of equations of motion, constitutive laws, and boundary conditions to model the lipid membrane and bulk fluid system are provided.

Alkadri, Ahmad M↗

DOE OSTI2023

Nanomotor-enhanced transport of passive Brownian particles in porous media

Artificial micro/nanomotors are expected to perform tasks in interface-rich and species-rich environments for biomedical and environmental applications. In these highly confined and interconnected pore spaces, active species may influence the motion of coexisting passive participants in unexpected ways. Using three-dimensional super-resolution single-nanoparticle tracking, we observed enhanced motion of passive nanoparticles due to the presence of dilute well-separated nanomotors in an interconnected pore space. This enhancement acted at distances that are large compared to the sizes of the particles and cavities, in contrast with the insignificant effect on the passive particles with the same dilute concentration of nanomotors in an unconfined liquid. Experiments and simulations suggested an amplification of hydrodynamic coupling between self-propelled and passive nanoparticles in the interconnected confined environment, which enhanced the effective energy for passive particles to escape cavities through small holes. This finding represents an emergent behavior of confined nanomotors and suggests new strategies for the development of antifouling membranes and drug delivery systems.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2022

Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

The invention provides electro-catalyst compositions for an anode electrode of an acid mediated proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using any solution based methods involving a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

Kumta, Prashant N.↗

DOE OSTI2021

Energy efficient membrane-based process for CO 2 capture

Processes and systems for the energy efficient capture of CO 2 from a flue gas stream such as produced or resulting from power plant operation, are provided. The processes and systems integrate the use of high CO 2 /N 2 selectivity membranes and high CO 2 flux membranes, to capture CO 2 . Useful membranes can desirably be graphene oxide-based membranes.

Li, Shiguang↗

DOE OSTI2021

Membrane-Based Air Dehumidification Using Organic Ionic Liquid Desiccant

Membrane Ionic Liquid Desiccant Air Dehumidification (MILDAD) is a promising alternative to conventional dehumidification systems that employ mechanical compressors and refrigerant-based cooling with evaporator and condensing coils. However, its application has been limited due to high manufacturing and installation cost, durability issues, concerns with corrosion due to leakage and salt carry over into the downstream air and onto surfaces. This paper reviews substantial progress made with new systems based on combining advanced ionic membranes that are pressure resistant, thin walled with high water permeability, and non-porous with synthetic organic, non-crystalline ionic liquid desiccants. Alternative design configurations are discussed comparing cross flow shell-and-tube membrane contactors employing ionic membrane tubes through which ionic liquid desiccant air flows. Performance data for MILDAD prototypes is provided. Dehumidification of the incoming supply airstream and regeneration into exhausted building air is demonstrated. The latent effectiveness of the MILDAD system will be discussed along with some future steps to improve performance of the system.

Bahar, Bamdad↗

DOE OSTI2022

Porous membrane enabled mass spectrometry characterization of microfluidic devices

A system for sampling a liquid includes a sample fluid conduit including a membrane having pores. The membrane prevents the passage of the sample liquid through the pores at a first pressure of the sample liquid in the sample fluid conduit. A surface sampling capture probe has a distal end. The capture probe includes a solvent supply conduit and a solvent exhaust conduit. A solvent composition flowing at the distal end of the capture probe establishes a liquid junction with the membrane and establishes a second pressure within the liquid junction at the membrane. The second pressure is lower than the first pressure. Sample liquid will be drawn through the pores of the membrane by the second pressure at the liquid junction. A method for sampling a liquid and for performing chemical analysis on a liquid are also disclosed.

Cahill, John F.↗

DOE OSTI2024

Porous membrane enabled mass spectrometry characterization of microfluidic devices

Cahill, John F.↗

DOE OSTI2024

Deuterium Permeation Through a Self-Supported Palladium-Silver Membrane in Helium Gas Mixtures

Palladium membranes and membrane reactors can separate and purify tritium from impurities in the plasma exhaust processing system for the fusion energy fuel cycle. Membranes can also act as a continuous separation method to remove tritium from helium streams in the breeder blanket tritium extraction system, such as from the purge gas of solid breeders. To investigate the potential of these membranes for these applications, we performed a deuterium permeation campaign with a self-supported palladium-silver (Pd-25Ag wt%) tube of 0.15 m length, 76 µ m wall thickness, and 3.0 mm inner diameter. A gas mixture of 3.95% D 2 and a balance of He was delivered to the inside of the tube and D permeated radially outwards through the membrane into a vacuum chamber. Permeation experiments were conducted at 300 ° C, 350 ° C, 400° C, and 450°C, from 100 to 1000 sccm total flow rate, and with total pressures of 90, 150, 190, and 250 kPa. Further, deuterium permeation was consistently lower than predicted from diffusion-limited permeation models, thus we developed a transport model that included gas-phase mass transfer and surface reactions to model experimental results. The dissociation constant was optimized to fit the developed model to experimental data.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2020

Highly quaternized polystyrene ionomers for high performance anion exchange membrane water electrolysers

Alkaline anion exchange membrane (AEM) electrolysers to produce hydrogen from water remain at an early stage of development, and their performance is far lower than that of systems based on proton exchange membranes. Here, we report an ammonium-enriched anion exchange ionomer that improves the performance of an AEM electrolyser to levels approaching that of state-of-the-art proton exchange membrane electrolysers. Using rotating-disk electrode experiments, we show that a high pH (>13) in the electrode binder is the critical factor for improving the activity of the hydrogen- and oxygen-evolution reactions in AEM electrolysers. Based on this observation, we prepared and tested several quaternized polystyrene electrode binders in an AEM electrolyser. Using the binder with the highest ionic concentration and a NiFe oxygen evolution catalyst, we demonstrated performance of 2.7 A cm -2 at 1.8 V without a corrosive circulating alkaline solution. The limited durability of the AEM electrolyser remains a challenge to be addressed in the future.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Characterization of Gramicidin A in Triblock and Diblock Polymersomes and Hybrid Vesicles via Continuous Wave Electron Paramagnetic Resonance Spectroscopy

Studying membrane proteins in a native environment is crucial to understanding their structural and/or functional studies. Often, widely accepted mimetic systems have limitations that prevent the study of some membrane proteins. Micelles, bicelles, and liposomes are common biomimetic systems but have problems with membrane compatibility, limited lipid composition, and heterogeneity. To overcome these limitations, polymersomes and hybrid vesicles have become popular alternatives. Polymersomes form from amphiphilic triblock or diblock copolymers and are considered more robust than liposomes. Hybrid vesicles are a combination of lipids and block copolymers that form vesicles composed of a mixture of the two. These hybrid vesicles are appealing because they have the native lipid environment of bilayers but also the stability and customizability of polymersomes. Gramicidin A was incorporated into these polymersomes and characterized using continuous wave electron paramagnetic resonance (CW-EPR) and transmission electron microscopy (TEM). EPR spectroscopy is a powerful biophysical technique used to study the structure and dynamic properties of membrane proteins in their native environment. Spectroscopic studies of gramicidin A have been limited to liposomes; in this study, the membrane peptide is studied in both polymersomes and hybrid vesicles using CW-EPR spectroscopy. Lineshape analysis of spin-labeled gramicidin A revealed linewidth broadening, suggesting that the thicker polymersome membranes restrict the motion of the spin label more when compared to liposome membranes. Statement of Significance: Understanding membrane proteins’ structures and functions is critical in the study of many diseases. In order to study them in a native environment, membrane mimetics must be developed that can be suitable for obtaining superior biophysical data quality to characterize structural dynamics while maintaining their native functions and structures. Many currently widely accepted methods have limitations, such as a loss of native structure and function, heterogeneous vesicle formation, restricted lipid types for the vesicle formation for many proteins, and experimental artifacts, which leaves rooms for the development of new biomembrane mimetics. The triblock and diblock polymersomes and hybrid versicles utilized in this study may overcome these limitations and provide the stability and customizability of polymersomes, keeping the biocompatibility and functionality of liposomes for EPR studies of membrane proteins.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Fabrication of ultrathin suspended membranes from atomic layer deposition films

In this report, ultrathin films suspended as freestanding membranes are critical to many microelectronic and materials science applications. However, fabrication methods are currently limited in either their flexibility, due to material selectivity issues during the final membrane release, or their scalability. Here, we demonstrate a novel fabrication process for suspending ultrathin films with thicknesses as low as 4 nm and lateral dimensions up to 20 x 1000 μm from a variety of materials grown by atomic layer deposition. A silicon nitride membrane serves as the support for a sacrificial polymer layer and an ultrathin atomic layer deposition film which, after plasma etching, will form the membrane. The high chemical selectivity between atomic layer deposition-grown transition metal nitrides and oxides and the sacrificial polymer means that ultrathin films of a variety of materials can be released without damage using a single process. Electrically conductive titanium nitride membranes can be produced by this method and are of significant interest for electron microscopy applications. Electron transparency of titanium nitride membranes was found to be ~14% higher than silicon nitride of the same thickness, and of similar conductivity to graphite, meaning that ultrathin, conductive, and electron transparent membranes can be fabricated at scale. These membranes are ideal supports for electron and photon characterization techniques, as well as microelectromechanical system applications that require a conductive membrane.

36 MATERIALS SCIENCE↗

DOE OSTI2021

An experimental study on dehumidification and regeneration performance of a new nonporous membrane-based heat and mass exchanger using an ionic liquid desiccant

As a promising alternative to inefficient vapor-compression-based air conditioning, liquid desiccant dehumidification uses a liquid desiccant in contact with the humid air absorbing the moisture. However, it has not gained much market share due to the issues related to the carryover, corrosion, fouling, and crystallization of liquid desiccant. The research has developed a new membrane-based exchanger, which uses a non-corrosive ionic liquid desiccant and nonporous tubular membranes to address these issues. As the second generation of the prototype, the new exchanger was tested at various operating conditions. According to the experimental data, when it is used in the dehumidification loop, the new membrane-based exchanger achieves a specific vapor transportation rate of 778.6 g/(h–m 2 ) and an average water vapor flux of 0.316 g/(h-m 2 -Pa), which is a significant improvement compared with the previous designs using nonporous membranes. It also achieved a comparable or even better dehumidification performance compared with the dehumidifiers that use porous membrane and conventional liquid desiccants. However, the regeneration performance is not as good as its dehumidification. It is mainly caused by the high operating temperature required in the regeneration loop. The experimental data and findings provide first-hand experimental data and enhance the understanding of advanced membrane-based ionic liquid desiccant systems.

42 ENGINEERING↗

DOE OSTI2024

An All-Soluble Fe/Mn-Based Alkaline Redox Flow Battery System

Redox flow batteries (RFBs) are membrane-separated rechargeable flow cells with redox electrolytes, offering the potential for large-scale energy storage and supporting renewable energy grids. Yet, creating a cost-effective, high-performance RFB system is challenging. In this work, we investigate an Fe/Mn RFB alkaline system based on the [(TEA)Fe–O–Fe(TEA)] 3– / 4– and MnO 4 – / 2– redox couples with a theoretical cell voltage of ~1.43 V. This combination has not been systematically studied previously, but it can lead to a very low-cost and sustainable materials for high energy storage. Constant current cycling tests were performed at ±41 mA cm –2 between 20% and 80% SOC over 800 h (400 cycles) with an apparent Coulombic efficiency (CE) approaching 100%, while the voltage efficiency (VE) gradually decreased from ~75.3% to ~61.4% due to increasing internal resistances. Finally, the voltage efficiency loss can be mitigated through a periodic acid treatment to remove MnO 2 deposits from the separator.

25 ENERGY STORAGE↗

DOE OSTI2020

Development of an Electrochemical Hydrogen Contaminant Detector

Hydrogen refueling stations (HRSs) that dispense hydrogen to fuel cell vehicles need to ensure the quality of hydrogen to avoid contamination of the vehicle’s expensive fuel cell stacks. Currently, stations verify their fuel quality only periodically to ensure that they meet the strict fuel quality standards specified by either International Organization for Standards (ISO) or Society for Automotive Engineers (SAE). The development of hydrogen contaminant detectors (HCDs) that can provide low cost continuous monitoring at the HRS can be an invaluable asset in protecting fuel cell vehicles from any fuel contamination in-between infrequent expensive analysis of hydrogen fuel quality. An HCD capable of detecting < 200 ppb of CO in hydrogen is presented in this paper. The HCD is based on an electrochemical hydrogen pumping cell whose ultra-low loaded working electrode is poisoned by the contaminant, thus reducing its hydrogen oxidation reaction rate. The hydrogen pumping cell consists of a Nafion® membrane, a sputtered Pt working electrode, a Pt/Ru counter/pseudo-reference electrode and an internal water wicking system that provides humidification to the membrane and electrodes. When this HCD is operated in a pulsed voltammetry mode, it can provide stable CO response for thousands of hours in a HRS.

47 OTHER INSTRUMENTATION↗

DOE OSTI2022

Methods and systems for producing nanolipoprotein particles

Provided herein are methods and systems for the production of a nanolipoprotein particle (NLP) that includes a scaffold protein a membrane forming lipid and optionally a target protein. At least one of the scaffold protein and target protein can be provided through an IVT system. The membrane forming lipid, scaffold protein and optionally the target protein can be assembled for a time and under conditions that allow obtaining high yield NLPs, NPLs with an increased solubility, an NLP of a controlled size, and/or an NLP having a size predetermined to include a pre-selected target protein.

Coleman, Matthew A.↗

DOE OSTI2024

High-Performance AEM LTE with Advanced Membranes, Ionomers and PGM-Free Electrodes

Alkaline low temperature electrolysis (LTE) systems enjoy several potential advantages over acid-based LTE systems including facile oxygen evolution reaction (OER) kinetics and electrodes that can use little to no platinum group metals (PGM). The polymer membranes and membrane electrode assembly (MEA) structures going into alkaline electrochemical systems have seen significant advances in recent years. The objective of this project is to combine state-of-the-art alkaline polymer electrolyzer components into one optimized membrane electrode assembly (MEA) system to achieve DOE low temperature electrolysis (LTE) goals. The benefit of individual component advances cannot be fully appreciated until all aspects and components of the MEA are working at an equally high level of performance. New electrode fabrication methods were developed where solvent cast catalyst/ionomer solutions were used in place of insoluble ionomers to significantly improve adhesion. The membranes were improved in terms of durability and mechanical properties. The OER and HER catalysts were improved and made more durable.

08 HYDROGEN↗

DOE OSTI2024

Insights into Probing the Effect of Molecular Weight of Poly(carboxybetaine methacrylate) on the Performance of Forward Osmosis Desalination

Zwitterionic polymers have proven to be a promising nonfouling material that can be applied in the design of selective layers of thin film composite (TFC) membranes. Extending the permeability and usage of TFC membranes have attracted increasing interest in membrane-based desalination processes since water-flux reduction associated with biofouling nowadays persists as a common challenge. By virtue of its strong hydration, this polymer category is very useful to counteract biofouling in marine and biomedical systems, but the benefits from their application in membrane technology are still emerging. The efficacy of the nonfouling property as a function of the polymer’s molecular weight remains unknown. In pursuit of that vision, this study fosters new scientific insights via probing different molecular weights of poly(carboxybetain methacrylate) (PCBMA) coated on the surface as a selective layer for the prepared TFC membranes. The coated zwitterionic membranes (zM) exhibited excellent performance in preventing water flux decay in a bench-scale forward osmosis system. The prepared zM membranes revealed enhanced hydrophilic properties and retained their operational water flux when compared to the control. Our results suggest that using an intermediate-size molecular weight (PCBMA M n 50,000) will result in the best operational performance. The intermediate size resulted in the lowest flux decline rate (R t ) of 0.01 ± 0.001 (zM-50) when compared to the unmodified control membrane 0.56 ± 0.071 (M0) after using a model BSA foulant solution. Furthermore, all coated membranes exhibited similar trends in the observed reverse salt flux profiles, as well. In conclusion, the constructed zM membranes will serve as a model to develop further selective layers in the construction of TFC membranes.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Ammonium Looping with Membrane Absorber and Distributed Stripper for Enhanced Algae Growth

The objective of this project is to conduct a comprehensive investigation to develop and demonstrate a practical, reliable, and cost-effective integrated carbon dioxide (CO 2 ) capture and biofixation process for algae production. This process utilizes a chemical hindered ammonium solution (NH 4 OH) as both a capture reagent and an algae nutrient. The membrane absorber employed in the system ensured minimal ammonia (NH 3 ) emissions in the treated flue gas. Additionally, distributed solar-energy powered strippers located near the bioreactor modules facilitate solvent regeneration and enable just-in-time delivery of CO 2 and NH 3 to the algae, thereby minimizing the pH swing for enhanced productivity. The proposed membrane CO 2 absorber and solar-powered stripper is designed and seamlessly integrated with the existing 0.1 MWth bench-scale CO 2 capture system (CCS) and open raceway ponds (ORPs) at the University of Kentucky Center for Applied Energy (UK CAER) campus. The entire integrated process has undergone construction, operation, testing, and analysis. Furthermore, technology has been evaluated with a techno-economic analysis (TEA), technology gap analysis (TGA), life-cycle analysis (LCA), and a technology maturation plan (TMP). This project was performed within two budget periods, 54 months in duration. There are fourteen Project Tasks, twelve Milestones and four Success Criteria.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗