Showing papers on "Permeation published in 1981"
TL;DR: In this paper, the potential limitations to the use of membranes for gas separation, one of the most difficult to overcome has been that of inadequate permeation rate, which applies not only to gas separations, but to all separations for which membranes have been used.
488 citations
TL;DR: In this article, a model which explains reported complex effects of feed composition and pressure on component permeabilities in high-pressure gas separators based on glassy polymer membranes is discussed, and potential deviations from the theory are discussed in terms of separable solubility and mobility-related effects.
Abstract: A model is discussed which explains reported complex effects of feed composition and pressure on component permeabilities in high-pressure gas separators based on glassy polymer membranes. A special form of Fick's law which accounts for the fact that penetrants in glassy polymers sorb into and diffuse through two different molecular environments provides the basis for the analysis of gas mixture permeation. Potential deviations from the theory are discussed in terms of separable solubility-and mobility-related effects.
219 citations
TL;DR: The permeability of plant cell walls to macromolecules may limit the ability of enzymes to alter the biochemical and physical properties of the wall.
Abstract: The permeability of plant cell walls to macromolecules may limit the ability of enzymes to alter the biochemical and physical properties of the wall. Proteins of molecular weight up to 60,000 can permeate a substantial portion of the cell wall. Measurements of wall permeability in which cells are exposed to hypertonic solutions of macromolecules may seriously underestimate wall permeability.
124 citations
Patent•
17 Dec 1981
TL;DR: A hollow fiber membrane-type fluid separation apparatus useful for selective separation of fluids in various techniques such as gas permeation, liquid permeation and dialysis, ultrafiltration, reverse osmosis is described in this article.
Abstract: A hollow fiber membrane-type fluid separation apparatus useful for selective separation of fluids in various techniques such as gas permeation, liquid permeation, dialysis, ultrafiltration, reverse osmosis, etc., which comprises at least one pair of unit structures which are arranged uniaxially in series within a cylindrical pressure vessel, said pair of unit structures comprising a pair of cylindrical hollow fiber assemblies having a selective permeability, a means for collecting permeated fluid, which is held between side tube sheets provided each at a terminal of the pair of cylindrical hollow fiber assemblies and is capable of collecting the fluid which passes through the side tube sheet, a permeation fluid pipe for taking out the permeated fluid, which penetrates perpendicularly the means for collecting a permeated fluid at the center, and a fitting means provided with a passageway for passing a concentrated fluid being not permeated, said passageway being arranged at around central region of the means for collecting a permeated fluid so as to surround the permeation fluid pipe.
119 citations
TL;DR: In this paper, important variables governing the permeation of copper ion through liquid membranes and their effects on the separation process are described, including membrane viscosity, treatment ratio, complexing agent concentration, internal droplet size, internal phase leakage, and copper concentration in the internal phase.
Abstract: Important variables governing the permeation of copper ion through liquid membranes and their effects on the separation process are described. These variables are membrane viscosity, treatment ratio (volume ratio of emulsion to feed in mixer), complexing agent concentration, internal droplet size, internal phase leakage, and copper concentration in the internal phase. The information is needed for scaling-up of equipment and further process development. The economic evaluation based on bench-scale pilot plant runs shows this process is 40% cheaper than solvent extraction.
118 citations
TL;DR: In this article, the authors measured the oxygen permeability of polymeric materials used for hard and soft contact lens applications using a gas-to-water oxygen permeation technique, where the oxygen is dissolved and measured with an oxygen analyzer.
82 citations
TL;DR: From analyses of permeability coefficients, it was demonstrated that release rates also were dependent on the initial drug load and the equilibrium water content of the polymer, and cross-membrane diffusion studies on films depleted of theirInitial drug load were verified.
65 citations
60 citations
IBM1
TL;DR: In this article, the authors found that conformally coating polyimides prevents their relaxing their swelling stresses to accommodate the motions of permeating water molecules, manifesting this inability through changes in the diffusion coefficient.
Abstract: Various freestanding, commercially available polyimides have been found to have virtually identical water permeation properties. However, conformally coating them prevents their relaxing their swelling stresses to accommodate the motions of permeating water molecules, manifesting this inability through changes in the diffusion coefficient.
56 citations
TL;DR: In this article, a series of poly(vinyl alcohol) membranes were modifed by radiation-induced graft copolymerization with acrylic acid and methacrylic acid monomers.
Abstract: A series of poly(vinyl alcohol) membranes were modifed by radiation-induced graft copolymerization with acrylic acid and methacrylic acid monomers. These grafted poly(vinyl alcohol) membranes were then tested for their separation and permeability characteristics in vacuum permeation and dialysis experiments. The permselectivity of the membranes toward methanol and water was studied on a vacuum permeation apparatus at 30, 40, and 50°C. The permeation process was found to be a temperature-activated process. The logarithm of the permeation rate varied linearly with the reciprocal of the absolute temperature. The permeability of the grafted membranes was found to increase with the degree of grafting, with no appreciable selectivity toward water in binary mixtures. The acrylic acid-grafted membranes generally showed greater improvement in permeability than the methacylic-grafted membranes. The permeability of the grafted membranes toward methanol, sodium chloride, urea, creatinine, and uric acid was studied in a dialyzer. In all cases, the grafted membranes showed an improved permeability toward these solutes over the commercial poly(vinyl alcohol) membranes. The dialysis results were then compared with those obtained for dialysis-grade cellophane membranes. For the case of sodium chloride, urea, and methanol, the permeability of the grafted membranes was comparable to that of cellophane. A comparison of commercial and grafted poly(vinyl alcohol) membranes in their permeability toward ionic solutes exhibited somewhat anomalous behavior in that the permeability of the commercial membranes was higher than that of the grafted membranes. This related to the ionic nature of the modified membrane. The permeability coefficients determined in the dialysis experiments were found to be directly related to the degree of hydration of the grafted membrane. This behavior was attributed to changes in the size and shape of voids within the membrane structure.
53 citations
TL;DR: In this article, the vapor penetration of 29 common laboratory solvents on 28 protective gloves using gas-phase, infrared spectrophotometric techniques to determine the permeation characteristics were identified.
Abstract: We have tested and measured the vapor penetration of 29 common laboratory solvents on 28 protective gloves using gas-phase, infrared spectrophotometric techniques to determine the permeation characteristics. Five different types of permeation behavior were identified. No one glove offered complete protection against all the solvents tested. The permeation rate of the solvent was found to be inversely proportional to glove thickness for a given manufacturer's material. Of two solvent mixtures tested, one exhibited a large, positive, synergistic rate.
TL;DR: In this article, the authors used the permeation time-lag method to determine the permeabilities, diffusion coefficients and solubilities of hydrogen and deuterium in type 304 stainless steel of three kinds of surface treated specimens; with oxide film, reduced by H2 gas and Pd coated.
Abstract: The permeation time-lag method have been used to determine the permeabilities, diffusion coefficients and solubilities of hydrogen and deuterium in type 304 stainless steel of three kinds of surface treated specimens; with oxide film, reduced by H2 gas and Pd coated. For the specimen with a thin oxide film the permeability increased abruptly at the temperature higher than 1,050 K owing to reduction of the oxide film by H2 gas introduced. The permeability and diffusion coefficient for hydrogen-reduced specimens agreed with those for Pd-coated specimens showing the data of bulk diffusion limited. The isotope effects for permeability ΦH/ΦD, diffusion coefficient D H/D D and solubility were about 1.4, 1.2 and 1.1, respectively. From these values θ(=hν/k)=1,530±50K and θ′(=hν/k)=2,740±20K were obtained by the quantum effect of a harmonic approximation.
TL;DR: In this article, the authors measured the deuterium permeation rate and reemission rate during the implantation of 20 keV deuteron with use of a quadrupole mass-spectrometer.
TL;DR: Permeability coefficients were determined for C-labelled compounds using canine and rabbit lingual frenulum as the test tissue, demonstrating the importance of lipid solubility on the rate of transfer across oral mucosa and suggesting two different routes of permeation for these compounds.
TL;DR: A method is described which permits the quantitation of the rate of permeation of 1311 through dog dentin, both in vivo and in vitro, indicating the rates are very similar.
Abstract: A method is described which permits the quantitation of the rate of permeation of 131I through dog dentin, both in vivo and in vitro. The results demonstrate the rapidity of the systemic appearance of substances placed on intact dentin. Comparison of the rate of permeation of 131I made in vivo and in vitro, on the same teeth, indicates the rates are very similar.
TL;DR: The passive permeation and facilitated diffusion of glycerol into Escherichia coli K 1060, an unsaturated fatty acid auxotroph, were studied as a function of temperature and membrane lipid fatty acid composition using a stopped-flow spectrophotometric assay of Glycerol permeation.
Abstract: SUMMARY: The passive permeation and facilitated diffusion of glycerol into Escherichia coli K1060, an unsaturated fatty acid auxotroph, were studied as a function of temperature and membrane lipid fatty acid composition using a stopped-flow spectrophotometric assay of glycerol permeation. The relative rates of glycerol passive and mediated entry were both significantly influenced by the fluidity of the membrane lipids, increasing as the gel to liquid-crystalline phase transition midpoint temperature of the membrane lipids decreased. The rate of passive glycerol permeation, but not the rate of glycerol facilitated diffusion, decreased as the membrane lipids were converted to the gel state. The apparent activation energies for passive and facilitated diffusion of glycerol, measured in cells whose membrane lipids were in the liquid-crystalline state, were 15–16 and 10–11 kcal mol-1, respectively, and neither value was significantly influenced by the fatty acid composition or fluidity of the membrane lipids. The mechanistic implications of these observations for the function of the glycerol facilitated diffusion system of E. coli are discussed.
TL;DR: Dynamic mechanical properties of Methocel HG membranes containing cyclodextrins suggest these additives to be antiplasticizing agents, and Concentration electrical potential and bi-ionic electrical potential in membranes containing the Schardingercyclodextrin show that the cyclodeXTrins are able to induce ion transport selectively through nonionic membranes.
Abstract: The permeation characteristics of the isomers of such aromatics as dichlorobenzenes, nitrochlorobenzenes, xylenes, etc, through a Methocel HG membrane containing various amounts of Schardinger α-cyclodextrin and β-cyclodextrin additives were measured in liquid/liquid dialysis and pervaporation experiments The results showed that the cyclodextrins are able to selectively mediate molecular transport through the Methocel HG membranes In general, increased membrane selectivity and a decrease in permeation rates were observed Permeation rates for some aromatic compounds were decreased several hundred times with only 25% amounts of additive cyclodextrins in the Methocel HG membranes Concentration electrical potential and bi-ionic electrical potential in membranes containing the Schardinger cyclodextrin have been measured and also show that the cyclodextrins are able to induce ion transport selectively through nonionic membranes Dynamic mechanical properties of Methocel HG membranes containing cyclodextrins suggest these additives to be antiplasticizing agents A mechanism for the modification of the intrinsic membrane permeation properties by cyclodextrin additive involving antiplasticizing action by the additives plus induced tortuous diffusion, where the latter is a result of specific interactions between the cyclodextrin additive and the permeating molecules, is proposed
TL;DR: In this paper, a study of water-ethanol permeation through grafted PTFE membranes containing small amounts of low-molecular-weight grafts is presented.
TL;DR: Measurements of the rate of permeation of 2 M glycerol and 1 and 2 M dimethylsulfoxide into 17-day fetal pancreases at 0 and 22 °C show kinetics more characteristic of a two-compartment than a single-compartments system.
Patent•
29 Sep 1981
TL;DR: In this article, the repetitive units of the specific formula as main chains on a porous membrane are used to obtain a membrane having high permeability and sepn. performance by coating an org. silicon high polymer compd. prepd.
Abstract: PURPOSE: To obtain a membrane having high permeability and sepn. performance by coating an org. silicon high polymer compd. contg. the repetitive units of the specific formula as main chains on a porous membrane. CONSTITUTION: The 1W50wt% soln. prepd. by dissolving the polymer or polysiloxane (about 500W100,000 number average mol.wts.) having the repetitive units shown in the formula in a solvent such as benzene, toluene, hexane or THF is coated on a porous membrane to 10W1,000μ thickness. The porous membrane is not particularly limited of materials and shapes as far as it has ≥1×10 -4 cm 2 / cm 2 .sec.cmHg rate of permeation. The rate of permeation[CC(STP)/cm 2 . sec.cmHg, ×10 -6 ]of the separating membrane produced from the polymer obtd. by the polymn. of chlorodimethyl chlorosilane in an embodiment is N 2 (5.2), O 2 (10), CO 2 (38), He(26). COPYRIGHT: (C)1983,JPO&Japio
Patent•
13 Mar 1981TL;DR: In this article, a hydrocrackate from a hydro-cracking zone operating under hydrocracking conditions is separated into at least one liquid phase and a separated vapor phase.
Abstract: A hydrocrackate from a hydrocracking zone operating under hydrocracking conditions is separated into at least one liquid phase and a separated vapor phase wherein the separated vapor phase has a greater concentration of hydrogen than the minimum concentration of hydrogen in the vapor phase in the hydrocracking zone At least a portion of the separated vapor phase is contacted with the feed side of a polymeric membrane selective to the permeation of hydrogen as compared to the permeation of methane, and the opposite side of the polymeric membrane is maintained at a pressure sufficiently below the pressure at the feed side of the polymeric membrane to permeate hydrogen to the opposite side of the polymeric membrane and to provide a hydrogen permeate having a concentration of hydrogen greater than the concentration of hydrogen in the separated vapor phase and greater than the concentration of hydrogen in the hydrogen feed gas The hydrogen permeate is compressed and recycled to the hydrocracking zone
TL;DR: Water, methanol, ethanol, and butanol as permeants and a previously developed procedure involving multiple, sequential permeation runs on each piece of skin, showing species differences in the hydration profiles appear related to the vastly dissimilar pellages and may indicate greater involvement of the transfollicular pathway.
TL;DR: The results show that the frequently used a priori assumption of partition equilibrium at the membrane interfaces during transport is not justified.
TL;DR: In this article, the permeation rate and transfer mechanism of copper(II) through a supported liquid membrane containing LIX65N as a mobile carrier were studied under the condition that the rate-determining step of the dialysis was the diffusion in the membrane.
Abstract: Permeation rate and transfer mechanism of copper(II) through a supported liquid membrane containing LIX65N as a mobile carrier were studied. The experiment was carried out under the condition that the rate-determining step of the dialysis was the diffusion in the membrane. The binary diffusivities of the oxime and the copper-oxime complex for solute-solvent system and apparent diffusivity of copper in the supported liquid membrane were measured. The apparent diffusivity of copper was approximately proportional to the -1.0 power of the liquid membrane solution viscosity. The copper flux was constant in the range of pH>3 in the feed solution, but decreased with decreasing pH in the range of pH<3. Copper concentration in the feed solution hardly influenced the copper flux in the range of 10-3-10-1 mol-dm-3. The copper flux was proportional to the 1st power of the oxime concentration in the liquid membrane when pH of the feed solution was 4.47, but the value of the power of the oxime concentration increased with decreasing value of pH of the feed solution. The concentration profile of the copper-oxime complex in a stack of the supported liquid membrane was approximately in agreement with the theory.
TL;DR: In this paper, the effect of polymer molecular weight on the structure and function of EVA copolymer membranes was investigated using a scanning electron microscope (SEM) and the microstructure was observed with the aid of a scanner.
TL;DR: In this paper, an apparatus for continuously monitoring of hydrogen gas dissolved in transformer oil, in which a polyimide membrane is used to separate the hydrogen from the oil, was presented.
Abstract: This report presents an apparatus for continuously monitoring of hydrogen gas dissolved in transformer oil, in which a polyimide membrane is used to separate the hydrogen from the oil. The hydrogen is allowed to permeate through the membrane and contact a gas sensor every 72 hours. The characteristics of the permeation of the hydrogen gas through the polyimide membrane and of the detection of the hydrogen gas by the gas sensor are described under various conditions. Problems encountered when the apparatus is installed on a tran are also studied and solved. As a result, this new apparatus was found useful in determining whether a transformer is operating normally or not.
TL;DR: The barnacle electrode hydrogen measurement device as discussed by the authors can accurately detect and measure diffusible hydrogen contents in the range of 100 parts per billion by weight, which can accurately indexing embrittlement of high strength AISI 4340 steel as a function of hydrogen content.
Abstract: The electrochemical measurement of mobile hydrogen, utilized in hydrogen-through-iron permeation studies, is adapted to yield an extremely sensitive, yet simple, practical device to assess embrittlement in high-strength steel parts. The electrochemical permeation of hydrogen through metal foils is achieved by causing an electrochemical source and sink for hydrogen to co-exist on either side of a foil. The hydrogen is cathodically introduced at the input side and anodically extracted (oxidized to water) at the exit side. The extraction side of the permeation cell provides the basis for the barnacle electrode hydrogen measurement device. The hydrogen oxidation current is measured and related to the mobile hydrogen concentration by the solution to the diffusion equation using the appropriate boundary conditions. The device can accurately detect and measure diffusible hydrogen contents in the range of 100 parts per billion by weight. Its effectiveness has been demonstrated in (I) indexing embrittlement of high-strength AISI 4340 steel as a function of hydrogen content, (2) the loss of hydrogen in an HY-130 steel weldment, and (3) changes in hydrogen content of cadmium plated steel which were measured, leading to a better understanding of bakeout and delayed failure mechanisms.