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Catherine H Crouch, Margaret H Bost, Tae H Kim, Bryan M Green, D Stuart Arbuckle, Carl H Grossman, Kathleen P Howard
We report the optimization of detergent-mediated reconstitution of an integral membrane-bound protein, full-length influenza M2 protein, by direct insertion into detergent-saturated liposomes. Detergent-mediated reconstitution is an important method for preparing proteoliposomes for studying membrane proteins, and must be optimized for each combination of protein and membrane constituents used. The purpose of the reconstitution was to prepare samples for site-directed spin-labeling electron paramagnetic resonance (SDSL-EPR) studies...
November 8, 2018: Membranes
Xi Ke, Marco Drache, Uwe Gohs, Ulrich Kunz, Sabine Beuermann
Polymer electrolyte membranes (PEM) prepared by radiation-induced graft copolymerization are investigated. For this purpose, commercial poly(ethylene-alt-tetrafluoroethylene) (ETFE) films were activated by electron beam treatment and subsequently grafted with the monomers glycidyl methacrylate (GMA), hydroxyethyl methacrylate (HEMA) and N , N '-methylenebis(acrylamide) (MBAA) as crosslinker. The target is to achieve a high degree of grafting ( DG ) and high proton conductivity. To evaluate the electrochemical performance, the PEMs were tested in a fuel cell and in a vanadium redox-flow battery (VRFB)...
November 6, 2018: Membranes
Emma Palo, Annarita Salladini, Barbara Morico, Vincenzo Palma, Antonio Ricca, Gaetano Iaquaniello
The development of a chemical industry characterized by resource efficiency, in particular with reference to energy use, is becoming a major issue and driver for the achievement of a sustainable chemical production. From an industrial point of view, several application areas, where energy saving and CO₂ emissions still represent a major concern, can take benefit from the application of membrane reactors. On this basis, different markets for membrane reactors are analyzed in this paper, and their technical feasibility is verified by proper experimentation at pilot level relevant to the following processes: (i) pure hydrogen production; (ii) synthetic fuels production; (iii) chemicals production...
November 1, 2018: Membranes
Liang Huang, Haiqing Lin
Sub-nanochannels constructed by stacking two-dimensional (2D) nanosheets in parallel provide a unique molecular separation pathway with excellent size-sieving ability for membrane gas separation. Herein we review the progress in engineering these 2D channels for efficient gas separation including graphene, graphene oxide (GO), molybdenum disulfide (MoS₂), and MXene. Mixed matrix materials containing these 2D materials in polymers are also reviewed and compared with conventional polymers for gas separation...
October 29, 2018: Membranes
Yulia Plekhanova, Sergei Tarasov, Vladimir Kolesov, Iren Kuznetsova, Maria Signore, Fabio Quaranta, Anatoly Reshetilov
The anode of a microbial fuel cell (MFC) was formed on a graphite electrode and immobilized Gluconobacter oxydans VKM-1280 bacterial cells. Immobilization was performed in chitosan, poly(vinyl alcohol) or N -vinylpyrrolidone-modified poly(vinyl alcohol). Ethanol was used as substrate. The anode was modified using multiwalled carbon nanotubes. The aim of the modification was to create a conductive network between cell lipid membranes, containing exposed pyrroloquinoline quinone (PQQ)-dependent alcoholdehydrogenases, and the electrode to facilitate electron transfer in the system...
October 25, 2018: Membranes
Francesco Dalena, Alessandro Senatore, Marco Basile, Sarra Knani, Angelo Basile, Adolfo Iulianelli
Methanol is currently considered one of the most useful chemical products and is a promising building block for obtaining more complex chemical compounds, such as acetic acid, methyl tertiary butyl ether, dimethyl ether, methylamine, etc. Methanol is the simplest alcohol, appearing as a colorless liquid and with a distinctive smell, and can be produced by converting CO₂ and H₂, with the further benefit of significantly reducing CO₂ emissions in the atmosphere. Indeed, methanol synthesis currently represents the second largest source of hydrogen consumption after ammonia production...
October 18, 2018: Membranes
Shamim Haider, Jon Arvid Lie, Arne Lindbråthen, May-Britt Hägg
The simultaneous carbonization of thousands of fibers in a horizontal furnace may result in fused fibers if carbonization residuals (tars) are not removed fast enough. The optimized purge gas flow rate and a small degree angle in the furnace position may enhance the yield of high quality carbon fibers up to 97% by removing by-products. The production process for several thousand carbon fibers in a single batch is reported. The aim was developing a pilot-scale system to produce carbon membranes. Cellulose-acetate fibers were transformed into regenerated cellulose through a de-acetylation process and the fibers were carbonized in a horizontally oriented three-zone furnace...
October 15, 2018: Membranes
Silvano Tosti, Alfonso Pozio
This paper reviews the membrane processes for the nuclear fusion fuel cycle-namely, the treatment of the plasma exhaust gases and the extraction of tritium from the breeding blankets. With respect to the traditional processes, the application of membrane reactors to the fusion fuel cycle reduces the tritium inventory and processing time, thus increasing the safety and availability of the system. As an example, self-supported Pd-alloy membrane tubes have been studied for the separation of hydrogen and its isotopes from both gas- and liquid-tritiated streams through water-gas shift and isotopic swamping reactions...
October 12, 2018: Membranes
Michael Z Hu, Chaiwat Engtrakul, Brian L Bischoff, Mi Lu, Mussie Alemseghed
Surface wettability-tailored porous ceramic/metallic membranes (in the tubular and planar disc form) were prepared and studied for both vapor-phase separation and liquid pervaporative separations of water-ethanol mixtures. Superhydrophobic nanoceramic membranes demonstrated more selective permeation of ethanol (relative to water) by cross-flow pervaporation of liquid ethanol⁻water mixture (10 wt % ethanol feed at 80 °C). In addition, both superhydrophilic and superhydrophobic membranes were tested for the vapor-phase separations of water⁻ethanol mixtures...
October 12, 2018: Membranes
Maria Alexandri, Roland Schneider, Joachim Venus
Lactic acid (LA) was produced on a pilot scale using a defined medium with glucose, acid whey, sugar bread and crust bread. The fermentation broths were then subjected to micro- and nanofiltration. Microfiltration efficiently separated the microbial cells. The highest average permeate flow flux was achieved for the defined medium (263.3 L/m²/h) and the lowest for the crust bread-based medium (103.8 L/m²/h). No LA losses were observed during microfiltration of the acid whey, whilst the highest retention of LA was 21...
October 12, 2018: Membranes
Bernardo Monteiro, Ana R Nabais, Maria H Casimiro, Ana P S Martins, Rute O Francisco, Luísa A Neves, Cláudia C L Pereira
The efficient separation of gases has industrial, economic, and environmental importance. Here, we report the improvement in gas separation performance of a polyimide-based matrix (Matrimid® 5218) filled with a Cu-based metal organic framework [MOF, Cu₃(BTC)₂] with two different ionic liquids (ILs) confined within the pores. The chosen ILs are commonly used in gas solubilization, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF₄]) and 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][OTf]), and the incorporation of the [EMIM][BF₄]@Cu-BTC and [EMIM][OTf]@Cu-BTC composites in Matrimid® 5218 proved to be an efficient strategy to improve the permeability and selectivity toward CO₂/N₂ and CO₂/CH₄ mixtures...
October 11, 2018: Membranes
Nicla Vicinanza, Ingeborg-Helene Svenum, Thijs Peters, Rune Bredesen, Hilde Venvik
Sputtered Pd77%Ag23% membranes of thickness 2.2⁻8.5 µm were subjected to a three-step heat treatment in air (HTA) to investigate the relation between thickness and the reported beneficial effects of HTA on hydrogen transport. The permeability experiments were complimented by volumetric hydrogen sorption measurements and atomic force microscopy (AFM) imaging in order to relate the observed effects to changes in hydrogen solubility and/or structure. The results show that the HTA-essentially an oxidation-reduction cycle-mainly affects the thinner membranes, with the hydrogen flux increasing stepwise upon HTA of each membrane side...
October 10, 2018: Membranes
Gregor Rudolph, Herje Schagerlöf, Kristian B Morkeberg Krogh, Ann-Sofi Jönsson, Frank Lipnizki
The pulp and paper industry is one of the most important industrial sectors worldwide, and has considerable potential for the sustainable fractionation of lignocellulosic biomass to provide valuable compounds. Ultrafiltration (UF) is a suitable separation technique for the profitable production of hemicelluloses from process water from thermomechanical pulping (ThMP), but is limited by membrane fouling. Improvements in cleaning protocols and new alternative cleaning agents are required to ensure a long membrane lifetime, and thus a sustainable process...
October 10, 2018: Membranes
Olof Gustafsson, Simon Gustafsson, Levon Manukyan, Albert Mihranyan
Pressure-dependent breakthrough of nanobioparticles in filtration was observed and it was related to depend on both convective forces due to flow and diffusion as a result of Brownian motion. The aim of this work was to investigate the significance of Brownian motion on nanoparticle and virus capture in a nanocellulose-based virus removal filter paper through theoretical modeling and filtration experiments. Local flow velocities in the pores of the filter paper were modeled through two different approaches (i...
October 5, 2018: Membranes
Qin Liu, Xing Wu, Kaisong Zhang
To improve the filtration performance and properties of organic solvent nanofiltration (OSN) membranes, we firstly introduce nanoporous silica (SiO₂) particles into the polyamide (PA) active layer of polysulfone (PSf) membrane via an interfacial polymerization process. Results from the study revealed that introduction of SiO₂ influenced the properties of PSf/PA-SiO₂ composite membranes by changing the surface roughness and hydrophilicity. Moreover, results also indicated that nanoporous SiO₂ modified membranes showed an improved performance of alcohols solvent permeance...
October 3, 2018: Membranes
Clàudia Fontàs, Enriqueta Anticó, Victòria Salvadó
A supported liquid membrane-hollow fiber system (HFSLM) has been developed to determine zinc speciation in aquatic environments. The liquid membrane consisted of an organic solution of bis-(2-ethylhexyl)phosphoric acid (D2EHPA) impregnated in the microporous of a polypropylene hollow fiber. The membrane contacted both the donor solution, that contained the metal and the stripping solution, placed in the lumen of the hollow fiber, where the metal was preconcentrated. Different parameters affecting the Zn2+ transport efficiency have been evaluated such as the composition of both the donor and stripping solutions as well as the membrane phase...
September 27, 2018: Membranes
Daria Nevstrueva, Arto Pihlajamäki, Juha Nikkola, Mika Mänttäri
Supported cellulose ultrafiltration membranes are cast from a cellulose-ionic liquid solution by the immersion precipitation technique. The effects of coagulation bath temperature and polymer concentration in the casting solution on the membrane morphology, wettability, pure water flux, molecular weight cut-off, and fouling resistance are studied. Scanning electron microscopy, contact angle measurements, atomic force microscopy, and filtration experiments are carried out in order to characterise the obtained ultrafiltration cellulose membranes...
September 25, 2018: Membranes
Nor Akalili Ahmad, Pei Sean Goh, Zulhairun Abdul Karim, Ahmad Fauzi Ismail
Oily wastewater discharge from various industry processes and activities have caused dramatic impacts on the human and environment. Treatment of oily wastewater using membrane technology has gained worldwide attention due to its efficiency in removing the amount and concentration of oil and grease as well as other specific pollutants in order to be reused or to fulfill stringent discharge standard. The application of thin film composite (TFC) membrane in reverse osmosis (RO) and forward osmosis (FO) for oily wastewater treatment is an emerging and exciting alternative in this field...
September 21, 2018: Membranes
Anbharasi Vanangamudi, Ludovic F Dumée, Mikel C Duke, Xing Yang
Controlling surface⁻protein interaction during wastewater treatment is the key motivation for developing functionally modified membranes. A new biocatalytic thermo-responsive poly vinylidene fluoride (PVDF)/nylon-6,6/poly( N -isopropylacrylamide)(PNIPAAm) ultrafiltration membrane was fabricated to achieve dual functionality of protein-digestion and thermo-responsive self-cleaning. The PVDF/nylon-6,6/PNIPAAm composite membranes were constructed by integrating a hydrophobic PVDF cast layer and hydrophilic nylon-6,6/PNIPAAm nanofiber layer on to which trypsin was covalently immobilized...
September 19, 2018: Membranes
Aminat Uzdenova, Anna Kovalenko, Makhamet Urtenov, Victor Nikonenko
The use of the Nernst⁻Planck and Poisson (NPP) equations allows computation of the space charge density near solution/electrode or solution/ion-exchange membrane interface. This is important in modelling ion transfer, especially when taking into account electroconvective transport. The most solutions in literature use the condition setting a potential difference in the system (potentiostatic or potentiodynamic mode). However, very often in practice and experiment (such as chronopotentiometry and voltammetry), the galvanostatic/galvanodynamic mode is applied...
September 19, 2018: Membranes
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