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951.
Leland M Vane 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2019,94(2):343-365
Organic solvents are widely used in a variety of industrial sectors. Reclaiming and reusing the solvents may be the most economically and environmentally beneficial option for managing spent solvents. Purifying the solvents to meet reuse specifications can be challenging. For hydrophilic solvents, water must be removed prior to reuse, yet many hydrophilic solvents form hard-to-separate azeotropic mixtures with water. Such mixtures make separation processes energy-intensive and cause economic challenges. The membrane processes pervaporation (PV) and vapor permeation (VP) can be less energy-intensive than distillation-based processes and have proven to be very effective in removing water from azeotropic mixtures. In PV/VP, separation is based on the solution–diffusion interaction between the dense permselective layer of the membrane and the solvent/water mixture. This review provides a state-of-the-science analysis of materials used as the selective layer(s) of PV/VP membranes in removing water from organic solvents. A variety of membrane materials, such as polymeric, inorganic, mixed matrix, and hybrid, have been reported in the literature. A small subset of these is commercially available and highlighted here: poly (vinyl alcohol), polyimides, amorphous perfluoro polymers, NaA zeolites, chabazite zeolites, T-type zeolites, and hybrid silicas. The typical performance characteristics and operating limits of these membranes are discussed. Solvents targeted by the United States Environmental Protection Agency for reclamation are emphasized and ten common solvents are chosen for analysis: acetonitrile, 1-butanol, N,N-dimethyl formamide, ethanol, methanol, methyl isobutyl ketone, methyl tert-butyl ether, tetrahydrofuran, acetone, and 2-propanol. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
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955.
Xiaochen Gu Jennifer L. Dannefaer Benjamin R. Collins 《Drug development and industrial pharmacy》2013,39(8):845-852
Ibuprofen, one of the mostly prescribed nonsteroidal anti-inflammatory drugs (NSAIDs), has been proposed as a topical medication for secondary prevention against skin damage induced by sunburn. The objective of this study was to characterize transmembrane permeation of ibuprofen and sunscreen oxybenzone across poly(dimethyl siloxane) (PDMS) membrane. In vitro diffusion studies were carried out at 37° and 45°C, using a series of ibuprofen and oxybenzone samples, either individually or in combination. Concentrations of ibuprofen and oxybenzone in the receptor compartment for up to 6 h were measured using a high-performance liquid chromatography (HPLC) assay. Ibuprofen and oxybenzone permeated across the PDMS membrane in all diffusion studies. When applied individually, permeation percentages of ibuprofen and oxybenzone ranged from 1.0 to 4.1% and from 13.2 to 25.8%, respectively. When applied in combination, permeation percentages of ibuprofen and oxybenzone were 0.3–1.4% and 7.8–24.3%, respectively. Transmembrane permeation was significantly suppressed when both compounds were present concurrently. High temperature promoted the diffusion process of oxybenzone; a linear correlation was also observed between oxybenzone concentration and its permeation. The proposed permeation enhancement between ibuprofen and oxybenzone was not observed from this study. The potential transdermal interaction and systemic absorption from concurrent application of topical analgesics and sunscreens thus requires further systematic evaluation. 相似文献
956.
采用原位水热法在粗糙大孔α-Al2O3载体管上预先合成Silicalite-1沸石, 程序升温焙烧该管后,用砂纸打磨管表面, 再用原位水热法在打磨后的管上二次合成Silicalite-1沸石膜. 利用XRD、SEM及单组分气体渗透实验对制备的沸石膜进行表征, 并初步考察了影响打磨修饰法制备Silicalite-1沸石膜性能的主要因素. 结果表明, 合成的沸石膜是典型的Silicalite-1;其晶粒排列紧密, 呈互锁生长, 表面平整, 无晶间孔或针孔存在. 打磨前水热预处理载体管的时间和砂纸型号对合成沸石的质量影响较大. 室温下, 打磨修饰法制备的Silicalite-1沸石膜的H2渗透率达到1.2×10-6mol/(m2·s·Pa), 且H2/N2、H2/SF6的理想分离系数分别达到3.9、20.6和84.8. 相似文献
957.
Rong Lu Takahisa Ishimura Katsuya Tsutida Takayuki Honda Tetsuo Miyakoshi 《应用聚合物科学杂志》2005,98(3):1055-1061
Hybrid lacquers that dry quickly in a low‐relative‐humidity environment were synthesized with the repeated kurome lacquer process and an organic silicone compound. An investigation by gel permeation chromatography showed that fractions with different molecular weights showed a lower monomer concentration than the pure kurome lacquer. Fourier transform infrared spectra of the hybrid lacquers revealed that absorption due to the ether of the quinone olefin and/or dibenzofuran appeared around 1470 and 1080 cm?1 and increased with the number of drying days. The gel fractions in the lacquer films increased according to the number of drying days, and this showed that the hybrid lacquers had higher gel fractions than the pure kurome lacquer in the initial stage of dryness. In addition, the drying mechanism of the hybrid lacquers was analyzed with an automatic drying time recorder and rigid‐body pendulum physical property testing measurements. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1055–1061, 2005 相似文献
958.
In this study a new permeation measurement equipment is presented which is shown to be capable of measuring low and high gas fluxes through different membranes. The new membrane support system which is introduced here is suitable for thin membranes (>10 μm) and is expected to provide more accurate results than the design used in earlier permeation measurements. 相似文献
959.
Toshinori Tsuru Ryousuke Igi Masakoto Kanezashi Tomohisa Yoshioka Shinji Fujisaki Yuji iwamoto 《American Institute of Chemical Engineers》2011,57(3):618-629
Silica and cobalt‐doped silica membranes that showed a high permeance of 1.8 × 10?7 mol m?2 s?1 Pa?1 and a H2/N2 permeance ratio of ~730, with excellent hydrothermal stability under steam pressure of 300 kPa, were successfully prepared. The permeation mechanism of gas molecules, focusing particularly on hydrogen and water vapor, was investigated in the 300–500°C range and is discussed based on the activation energy of permeation and the selectivity of gaseous molecules. The activation energy of H2 permeation correlated well with the permeance ratio of He/H2 for porous silica membranes prepared by sol–gel processing, chemical vapor deposition (CVD), and vitreous glasses, indicating that similar amorphous silica network structures were formed. The permeance ratios of H2/H2O were found to range from 5 to 40, that is, hydrogen (kinetic diameter: 0.289 nm) was always more permeable than water (0.265 nm). © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献
960.
The main objective of the present investigation was to study the susceptibility to hydrogen damage on a type API 5L X52 steel welded by electrical resistance. Several techniques, such as hydrogen permeation and cathodic charging, were used. The metallic material was characterized using a scanning electron microscope and transmission electron microscope. The base metal microstructure was very similar to that of the one corresponding to the welded area. This microstructure mainly comprised ferrite and perlite, differing only in the grain size. Therefore, the susceptibility to hydrogen damage was similar in both cases. It is worth mentioning that the welded area has a very small dimension. Indeed, the fusion zone is only 5 mm wide while the heat affected zone is 1 mm wide. The hydrogen damage observed was mainly in the form of blisters, which were associated with the presence of aluminium-rich inclusions. Also, partial dissolution of inclusions and some matrix attack adjacent to the inclusions were noticed. 相似文献