Nanometer thin membranes with considerable application potential in micro mechanics and materials science can be prepared by transferring cross-linked monomolecular layers of polyisoprenes or polyisobutenes with ionic head groups from the water surface to solid substrates with holes. Especially if monolayers of low glass transition polymers are cross-linked, elastomeric membranes are obtained, which might find application in micro mechanical devices like membrane valves and pumps. Incorporation of hydrophobised colloids leads to composite membranes, which can be converted into porous membranes via removal of the colloids.

The aim of this work is to study the uses of electrodialysis to bentonitics clays dispersions from Boa Vista City, PB, to improve the rheological properties. The dispersions were prepared with natural clay in the concentration of 4.86% w/w and submitted to electrodialysis process by using cationic polymeric membranes. Following, the dispersions were treated with Na2CO3. After cure, it was evaluated apparent (AV) and plastic (PV) viscosity and water loss (WL). The tests was setting up according to 22 experimental design, with three measures in the central point, to estimate the best applied voltage and time and the influence on AV, PV and WL. The results showed that variables (voltage and time) have significant influence on the rheological properties. It was observed an increase in PV and decrease in WL, with values that satisfy the specifications for water based drilling fluids.

For using as separative membranes based on magnetic selectivity, nanoporous ferrimagnetic membranes of maghemite (γ-Fe2O3) and cobalt ferrite (Fe2CoO4) were prepared by the sol-gel route from ferrofluid colloidal solutions. Their magnetic properties were examined by superconductor quantum interference device (SQUID), and their structures and porous textures were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption-desorption analyses. O2-N2 adsorption and air separation experiments were carried out in order to evidence magnetic interactions in static and dynamic conditions, respectively. A small effect of an external magnetic field on the selectivity of these membranes was observed.

Experimental results for flocculation of yeast and CHO cells using cationic polyelectrolytes are presented. These results suggest the existence of a self-similar floc size distribution. The experimentally determined floc size distributions have been modelled using a population balance approach. For flocculated yeast suspensions, the variation of the floc volume fraction with dimensionless particle diameter is predicted by the population balance model assuming a binary fragment distribution function. However, for CHO cell flocs, the floc volume fraction is predicted using a log normal fragment distribution function. Since the efficiency of unit operations such as microfiltration may be improved by flocculation of the feed suspension characterization of the particle size distribution is of great importance.

In the present work we study the relation between structural and permeation properties of ceramic membranes made by the sol-gel process. For this purpose, we have developed γ-Al2O3 mesoporous membranes via the sol-gel route, on top of multi-layer asymmetric α-Al2O3 macroporous supports, to induce mechanical stability. Subsequently, we employ stochastic techniques to generate three-dimensional reconstructions of the membrane and the support that share the basic structural properties of the original materials determined directly from SEM and TEM studies. The permeability of each material is estimated by solving numerically the momentum equation in the void space of the reconstructed images. The very good agreement between predicted and experimentally measured permeability values, without the need to resort to any fitting parameter, renders the proposed reconstruction methodology quite promising for reliable characterization and representation of the pore structure of this type of membranes.

Zeolite particles formed in the synthesis solution assume a negative charge due to electrical double layer effects. The membranes synthesized via electrophoretic deposition produce a thin continuous zeolite ZSM-5 layer on the porous alumina substrates. The thickness of membranes can be controlled by varying the precursor concentration, applied potential, and synthesis time. The permeation for a variety of gases through the membranes is examined. The diffusion properties are measured at near ambient temperature and pressure. Selectivity of n-butane over iso-butane is observed on every membrane. The diffusion coefficient of gases on ZSM-5 is also evaluated by gas adsorption on zeolite powders. The results of these studies show an ability to predict the effective diffusion coefficients. The estimation of molar fluxes across the membranes using the Maxwell-Stefan approach predicts a higher flux for thinner membranes. However, the calculations also show that even minor defects in the membrane have a great effect on the permeation rates.

The overall objective of the Electrospinning program at Foster-Miller is to develop a semi-automated, pilot scale machinery capable of producing nanofiber membranes at reasonable scales so that they can be evaluated for a wide range of military and commercial applications. This paper discusses the development of a high throughput electrospinning process

Aim of the present work is the investigation of the transport properties (Knudsen and molecular diffusivity, permeability) of 3-dimensional binary domains that represent two model mesoporous materials, namely Vycor glass and alumina membrane. A process-based technique producing a random packing of equal spheres is used for the reconstruction of the alumina membrane, while a stochastic reconstruction procedure is employed in the case of Vycor. The comparison between computed and reported transport coefficients confirms that the random sphere pack represents quite well the porous structure of the alumina membrane, while the stochastic reconstruction technique is sufficient for an accurate representation of the porous matrix of Vycor glass.

The hydrophilic group was substituted with separation distance of 100μm in a porous poly-tetrafluoroethylene (PTFE) membrane by ArF laser irradiation. With the micro domain structure of hydrophilic and hydrophobic groups in the porous PTFE, the membrane was modified to be fibrin and fat- free. Furthermore, the differential osmotic pressure was controlled freely by changing the density of the hydrophilic group into the porous PTFE. As a result, we developed the glaucoma implant membrane that is free from fibrin and fat and inhibits the graft rejection in the human body.

Zeolite Membranes Were Prepared On A Porous Ceramic Support By Hydrothermal Synthesis Using Conventional Heating System And Microwave Heating. Naa And T Type Zeolite Membranes Were Highly Selective For Permeating Water Preferentially With The High Permeation Flux, While Silicalite Membranes Exhibited Preferential Organic Compound Permeation From Water Such As Ethanol/Water. Nay And Nax Zeolite Membranes Showed A High Alcohol Selectivity For Several Feed Mixtures With Methanol Or Ethanol And A High Benzene Selectivity For Benzene/Cyclohexane And Benzene/N-Hexane Separation. The Performance Of The Zeolite Membranes Was The Most Favorable One For Pervaporation Membranes Which Have Been Published So Far And A Tubular Type Module Using A Type Zeolite Membrane For Dehydration Of Organic Liquids Has Been Put Into Industrial Operation. The Tubular Type Pervaporation And Vapor Permeation Module Can Produce 99.8 Wt% Ethanol From 600 L/H, 90 Wt% Ethanol Feed At 120 °C. For The Mass Production Of Zeolite Membrane A New Synthetic Method Using A Microwave Heating Is Also Proposed.

The transport of ions from aqueous solutions through a stacked Au/α-Al2O3/γ-Al2O3/Au membrane under the influence of a dc potential difference is reported. The membrane shows high cation permselectivity at ionic strengths of ∼10-3 M at pH 4.3–6.5, which is associated with a combination of anion adsorption and double-layer overlap inside the pores of the γ-alumina layer. The cation flux can be controlled by ionic strength, dc potential difference and pH.

Hemodialysis membranes are exposed to bleach during standard reprocessing methods, but there is little quantitative understanding of the effects of bleach on the mass transfer characteristics or surface properties of these membranes. A battery of experiments was used to evaluate the effects of bleach on the properties of Fresenius F80A, F80B, and Optiflux 180A dialyzers. Bleach caused a significant increase in the membrane hydraulic permeability. The clearance of urea (MW=60 Da) increased by only 3% after a 1-hour exposure to bleach at 50 °C compared to more than a 10-fold increase in the clearance of a 15 kD MW dextran. The solute clearance data were used to determine the effective membrane pore size using available hydrodynamic models. Bleach caused a significant increase in the effective pore size, which was attributed to the leaching of the polyvinylpyrrolidone (PVP) out of the polysulfone membrane. Bleach also caused a significant increase in the magnitude of the negative charge on the membrane surface; the zeta potential varied from −4.1 mV for the new membrane to −13.0 mV after a 14-hour exposure to bleach. These changes in pore size and surface properties provide important insights into the effects of bleach on hemodialysis membranes.

In the last two decades substantial progress has been made in the preparation of Carbon Molecular Sieve (CMS) membranes for gas separation. Today, researchers actively study precursor materials and pyrolysis routes to fully explore the merits of CMS membranes. Successful separation of permanent gas mixtures in which the gaseous components posses only little to no affinity to adsorb onto the internal CMS surface relies highly on the exact tailoring of microsieving regions. Preparation of CMS structures, which are highly permselective towards one of such mixture components, is especially cumbersome if the molecular sizes differ only slightly (e.g. O2/N2).

To facilitate the separation of O2 and N2 we have chosen to functionalize the carbon matrix. By introducing nano-sized (40 nm) metallic Ag-clusters, the affinity of the membrane matrix for O2 significantly increases. We have added a silver containing salt, AgNO3, to a solution of BMTA-TDI/MDI co-polyimide (P84, Lenzing) in NMP in the absence of light to obtain homogeneous flat film polymeric precursors. These precursors were pyrolysed, reducing Ag+ to Ag, at different temperatures (350, 500, 600, 700, and 800 °C) in a N2 atmosphere and characterized using Scanning Electron Microscopy, Atomic Force Microscopy, and gas permeation. Thermo Gravimetrical Analysis was used to follow the pyrolysis in detail. From this we observed an increase of the ideal separation factor of 1.6. Moreover, we observed an increase of the permeability to a maximum of 240 %.

Permselective separation of aromatic from non-aromatic hydrocarbons in feed streams can be accomplished by using membrane systems in hyperfiltration mode. In petrochemical or refinery operations, feed streams containing aromatics such as benzene, toluene, or xylenes can be selectively enriched or depleted in aromatics content. The development program for the STARMEM™ series of membranes led to a commercial process for their large-scale manufacture. A range of membranes in terms of flux and selectivity has been made, and both 2-inch and commercial scale 8-inch diameter spiral wound elements manufactured from these membranes. Tests at 800 psi (55 bar) and 50 °C with a toluene recycle stream have shown stable operation of these modules in hot hydrocarbons. The high efficiencies of these modules allow for high stage cuts (50% and greater) from process streams of thousands of barrels per day. By combining existing refinery operations such as distillation with these new membrane units, cost savings through better purity, recovery, or through-put can be achieved. With these membranes acting as tight hyperfiltration devices, the permeation properties can be modeled through a solution-diffusion equation for molecular transport. Since these membranes also act as solvent resistant nanofiltration devices, unusual benefits can be found while practicing aromatics enrichment of refinery streams, including fractionation of different molecular weight species.

This study focused on the impact of virgin polymer structure and microstructure on the transport properties of irradiated polyimide. Two fluorine containing polyimide isomers (6FDA-6FpDA and 6FDA-6FmDA) that differ solely in the location of the linkage between the diamine and dianhydride residues were used for this study. While these polymers differ in the location of a single bond, the virgin transport properties are dramatically different. The para connected isomer (6FDA-6FpDA) has much higher permeabilities and lower selectivities than the meta connect isomer (6FDA-6FmDA). The pure gas permeabilities in polyimide-ceramic composite membranes following H+ ion irradiation over a wide range of doses will be compared for these polyimide isomers. In addition, the evolution in chemical structure was monitored using Fourier transform infrared spectroscopy (FTIR). These polymers exhibited different decay rate in chemical structure following ion irradiation. Interestingly, the evolution in gas transport properties of these polymers following H+ ion irradiation was also quite different. We will discuss how the microstructure would affect the gas permeation properties of ion beam modification of polymer.

Polymeric membranes are widely used in biomedical field for bioartificial organs, medical devices and disposable clinical apparatus. Clinical utilization of blood-contacting devices requires the development of biomaterials with improved blood compatibility. The aim of this work was the exploration of a potential biocompatible membrane derived from a modified polyetheretherketone such as PEEK-WC. The surface affinity of this membrane to human plasma and plasmatic proteins such as albumin, fibrinogen and immunoglobulin G was compared to that of some commercial membranes. Changes with time of the membrane interfacial properties were evaluated by means of contact angle measurements using human protein solutions and human plasma. The extent of plasma protein adsorption on all investigated membranes was measured by comparing the behavior of the different polymer surfaces when contacting the three plasmatic proteins.

The sol-gel techniques were applied to fabricate some improved porous SiO2-ZrO2(50%) membranes for separation of organic solvents/water mixtures by pervaporation and vapor permeation methods at the normal boiling points of mixtures such as iso-propanol(IPA)/water and 1-propanol /water mixtures. The porous SiO2-ZrO2 membranes were found quite stable even at a high water content in the feed mixtures. They showed quite large pervaporation fluxes more than 450moles/(m2h) at 73mol% of IPA in the feed, for example, while the water flux for vapor phase separation at the same conditions was around 250mol/(m2h). The separation characteristics of organic chemicals/water mixtures by pervaporation and the vapor permeation methods are largely different in many points. Especially in this work separation by vapor permeation has been studied to compare with that of pervaporation taking into account the vapor-liquid equilibrium characteristics of the mixtures.

Novel macro and meso porous polysulfone materials were prepared from miscible blends of polysulfones with a phenylindane containing polyimide by chemically decomposing the polyimide phase with a dilute hydrazine solution in methanol. The polyether sulfone meso porous membranes are transparent films, with uniform pore sizes in the range of 30 nm. On the other hand, bisphenol A polysulfone based porous materials are opaque with pore sizes in the range of 200 nm.

In this work the growth of both a zeolite (MFI) and a zeolite-like material (SOD) were investigated in/on αAl2O3 tubular support, using hydrothermal conditions and microwave (MW) heating. The method reveals efficient for the rapid synthesis of MFI/αAl2O3 membranes although gentle conditions were required in order to limit the thermal degradation of the template. Promising results were also obtained for directly growing SOD in/on the support. In both MFI and SOD MW synthesis the chemical dissolution of the αAl2O3 support influences the final membrane characteristics. In the case of SOD synthesis, this phenomena which increases with both temperature and support size, alters the membrane homogeneity (composition and structure). In order to get round it, MWs were used to prepare SOD small crystals which were deposited on/in the αAl2O3 support and submitted to a secondary growth. Homogeneous membranes were then obtained whose ideal selectivities αH2/N2 and αHe/N2 reaches respectively 4.5 at 20°C and 6.2 at 115°C (these selectivities are lower than 2 for a ZSM-5 membrane in similar conditions).

Atomic scale dynamic theories and numerical simulation can explore atomistic processes but the relevant physics must fold atomistic understanding into a mesoscopic formulation in terms of average system properties. Transport equations for the density(or concentration), the flux and the pressure tensor are derived from a microscopic basis which mimics simulation by molecular dynamics. The validity of classical hydrodynamics is explored. The method includes interparticle interactions and small scale variations in time and space of relevance to modeling of membrane processes.