Composite carbon fluid separation membranes

The invention provides carbon membranes for use in fluid separation processes, particularly gas separations, which are treated with a coating that provides a protective barrier which significantly limits permeation of water vapor or other impurities such as hydrocarbons without significantly inhibiting permeation of the faster fluid component or lowering selectivity. The composite membranes retain good fluid separation properties and are resistant to the adverse effects on membrane performance commonly observed in environments having high humidity. The coating is preferably an amorphous polymer of perfluoro-2,2-dimethyl-1,3-dioxole. The membranes can be of a varied configuration: sheet form, hollow fiber, asymmetrical membranes and the like.Board of Regents, University of Texas Syste

Permeation of Several Gases through Elastomers, with Emphasis on the Deuterium/hydrogen Pair

The Diffusion and Permeation Coefficients for He, H2, D2, O2, and N2 in a Variety of Elastomers Were Measured by Simple Manometric Methods. the Elastomers Studied Were Butyl Rubber; Hypalon® 40 and 45; Viton® E60 and GF; Hydrin® 100 and Filled Hydrin® 100; Kraton® G, FG, and KG VTEOS; EPDM; Epoxidized Natural Rubber; and Neoprene. Consistent with Earlier Studies, Elastomers with Higher Glass Transition Temperatures Exhibited Lower Diffusion Coefficients. the Ratio of Diffusion Coefficients of the Hydrogen Isotope Pair Differed from the Purely Molecular‐weight‐based Prediction. Deuterium\u27s Slightly Smaller Size Relative to Hydrogen is Consistent with Observed Deviations from the Molecular‐weight‐based Diffusion Coefficient Ratio. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc

Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications. Final report

During the three years of support under this grant, ten novel polymer structures have been synthesized and characterized in detail in terms of sorption and transport properties to test the hypotheses on strategies to develop advanced materials for gas separation membranes. The extremely important O{sub 2}/N{sub 2} and CO{sub 2}/CH{sub 4} systems have been the focus of this work. Data for permeabilities and permselectivities for O{sub 2}/N{sub 2} and CO{sub 2}/CH{sub 4} at 35 C at approximately 2 atm feed pressure for O{sub 2} and N{sub 2} and 10 atm for CO{sub 2} and CH{sub 4} are reported in two tables and will be discussed in two parts, one related to each of the groups of structures in these two tables. For the sake of efficiency, the author will only consider the O{sub 2}/N{sub 2} data; however, similar trends apply for the CO{sub 2}/CH{sub 4} system as well. This gas pair is useful, since solubility selectivity effects are generally of much smaller importance than for the CO{sub 2}/CH{sub 4} pair, so even without detailed solubility and diffusivity data, mobility selectivity based arguments tend to be adequate

Polyimide hollow fiber membranes for CO2 separation from wet gas mixtures

Matrimid®5218 hollow fiber membranes were prepared using the dry-wet spinning process. The transport properties were measured with pure gases (H2, CO2, N2, CH4 and O2) and with a mixture (30% CO2 and 70% N2) in dry and wet conditions at 25 ºC, 50 ºC, 60 ºC and 75 ºC and up to 600 kPa. Interesting values of single gas selectivity up to 60 ºC (between 31 and 28 for CO2/N2 and between 33 and 30 for CO2/CH4) in dry condition were obtained. The separation factor measured for the mixture was 20% lower compared to the single gas selectivity, in the whole temperature range analyzed. In saturation conditions the data showed that water influences the performance of the membranes, inducing a reduction of the permeance of all gases. Moreover, the presence of water caused a decrease of single gas selectivity and separation factor, although not so significant, highlighting the very high water resistance of hollow fiber membrane modules

Ethnopharmacological survey of Samburu district, Kenya

<p>Abstract</p> <p>Background</p> <p>Ethnobotanical pharmacopoeia is confidently used in disease intervention and there is need for documentation and preservation of traditional medical knowledge to bolster the discovery of novel drugs. The objective of the present study was to document the indigenous medicinal plant utilization, management and their extinction threats in Samburu District, Kenya.</p> <p>Methods</p> <p>Field research was conducted in six divisions of Samburu District in Kenya. We randomly sampled 100 consented interviewees stratified by age, gender, occupation and level of education. We collected plant use data through semi-structured questionnaires; transect walks, oral interviews and focus groups discussions. Voucher specimens of all cited botanic species were collected and deposited at University of Nairobi's botany herbarium.</p> <p>Results</p> <p>Data on plant use from the informants yielded 990 citations on 56 medicinal plant species, which are used to treat 54 different animal and human diseases including; malaria, digestive disorders, respiratory syndromes and ectoparasites.</p> <p>Conclusion</p> <p>The ethnomedicinal use of plant species was documented in the study area for treatment of both human and veterinary diseases. The local population has high ethnobotanical knowledge and has adopted sound management conservation practices. The major threatening factors reported were anthropogenic and natural. Ethnomedical documentation and sustainable plant utilization can support drug discovery efforts in developing countries.</p

Purification of Propylene and Ethylene by a Robust Metal–Organic Framework Mediated by Host–Guest Interactions

From Wiley via Jisc Publications RouterHistory: received 2021-03-19, pub-electronic 2021-06-07Article version: VoRPublication status: PublishedFunder: Engineering and Physical Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/I011870, EP/R00661X/1, EP/S019367/1, EP/P025021/1, EP/P025498/1Funder: European Research Council; Id: http://dx.doi.org/10.13039/501100000781; Grant(s): 742401Abstract: Industrial purification of propylene and ethylene requires cryogenic distillation and selective hydrogenation over palladium catalysts to remove propane, ethane and/or trace amounts of acetylene. Here, we report the excellent separation of equimolar mixtures of propylene/propane and ethylene/ethane, and of a 1/100 mixture of acetylene/ethylene by a highly robust microporous material, MFM‐520, under dynamic conditions. In situ synchrotron single crystal X‐ray diffraction, inelastic neutron scattering and analysis of adsorption thermodynamic parameters reveal that a series of synergistic host–guest interactions involving hydrogen bonding and π⋅⋅⋅π stacking interactions underpin the cooperative binding of alkenes within the pore. Notably, the optimal pore geometry of the material enables selective accommodation of acetylene. The practical potential of this porous material has been demonstrated by fabricating mixed‐matrix membranes comprising MFM‐520, Matrimid and PIM‐1, and these exhibit not only a high permeability for propylene (≈1984 Barrer), but also a separation factor of 7.8 for an equimolar mixture of propylene/propane at 298 K