二元醇/水溶液在渗透蒸发均质膜中的扩散模型

用交联聚乙烯酸膜对不同浓度的乙二醇/水溶液在不同温度下分别进行了渗透蒸发实验研究．针对小分子在致密膜中的扩散行为提出了一个新见解,并借用改进的Vigne方程得到了一个新的热力学扩散系数方程,用此方程结合Lee-Thods方程、Wilke-Chang方程、Vrentas和Duda改进的自由体积理论、扩散方程和溶胀平衡方程预测了水和乙二醇分子在不同温度下通过交联聚乙烯醇膜的渗透蒸发行为,其预测结果与实验值基本一致．     

渗透蒸发过程非平衡溶解扩散模型

<正> 目前,关于渗透蒸发膜过程的机理研究已有不少成果’‘－‘’,这些工作归纳起来就是（平 衡）溶解－扩散模型．以聚乙烯醇膜分离乙醇－水体系为例,渗透蒸发过程中组分通过膜的传递 可以分为3个步骤：、（）乙醇、水溶解到膜的表面并达到溶解平衡;（2）水和乙醇依靠浓度梯 度扩散到膜的真空侧表面;（3）水和乙醇进入真空侧汽相．     

二元水溶液渗透蒸发膜扩散过程的修正自由体积模型

在自由体积扩散理论的基础上,提出了渗透蒸发过程中二元水溶液在聚合物膜中扩散的修正自由体积模型。模型中定义了2个共存因子,用以描述非理想物系在渗透蒸发膜扩散过程中的共存效应。结合4种水溶液在聚酰亚胺(PMDA-ODA)膜中的吸附实验数据所计算的膜相浓度,用本模型拟合了上述物系的渗透蒸发实验数据,获得较一致的结果。     

共混高分子膜渗透蒸发分离乙醇水溶液

应用湿法离子交联技术，研制了聚砜酰胺共混聚丙烯酸复合膜，针对乙醇水溶液，测定了膜的分离系数和渗透通量。实验发现，这种共混膜对乙醇－水具有较高的分离选择性。     

硅橡胶复合膜用于渗透蒸发的膜传质动力学(Ⅱ)膜内的扩散传质

The pervaporation of organics from dilute aqueous solution through a novel plate composite silicone rubber membrane was investigated. The measured and derived data indicated that the composite membrane possessed very high permeation flux and stable selectivity for dilute organic aqueous solution. Based upon the well- known resistance-in- series model, diffusive mass transfer behavior in membrane was investigated by calculation from the measured data with different skin layer thickness of membranes. The experimental results showed that the diffusive mass transfer coefficient conformed to Arrhenius correlation with temperature and was independent of the flow status. The diffusivities of the given alcohols in membrane had an order of magnitude 10 m-10·s-1 at a wider range of temperature, which is similar to those reported in literatures.     

水溶液中挥发性有机化合物渗透蒸发分离技术

介绍了水溶液中挥发性有机化合物 (VOCs)的各种分离方法 ,重点分析了渗透蒸发分离技术经济优势。阐释了渗透蒸发膜的选择标准、渗透蒸发过程的传质机理 ,以及原料液浓度、原料液温度、原料液流量、渗透侧压力、添加剂和膜组件型式等因素对渗透蒸发过程分离效率的影响 ,并简要预测了渗透蒸发过程的发展趋势与动态。     

渗透蒸发均质膜在二元醇/水溶液中的溶胀平衡模型

对交联聚乙烯醇均质膜于全浓度范围的乙二醇／水溶液中分别在60、70和80℃下进行了溶胀平衡实验研究.基于改进的UNIQUAC方程和Flory-Huggins热力学理论，建立了液-膜两相溶胀平衡模型方程，并用该模型方程计算出了水和乙二醇分子在交联聚乙烯醇均质膜中的溶解平衡浓度，其计算结果与实验值吻合良好.     

渗透蒸发膜及其在酯化反应过程中的应用

根据３０余篇文献及有关的技术资料，从膜的结构，膜制备的材料，制备方法及表征等方面总结了近１０年来渗透蒸发膜国内外的研究情况，以及将渗透蒸发膜应用酯化反应体系的研究成果和动态。     

粒子增强型中空纤维渗透蒸发分离有机水溶液

在选用粒子增强聚丙烯的基膜的基础上,制备了壳聚糖／聚丙烯腈（CS／PAN）中空纤维复合,考察了该膜对乙醇／水,异丙醇／水,丙酮／水体系的渗透蒸发分离特性,讨论并对比了料液浓度,温度对不同体系分离性能的影响。     

交联聚乙烯醇膜渗透蒸发分离乙二醇－水混合物的溶解选择性与渗透选择性的关系

交联聚乙烯醇膜渗透蒸发分离乙二醇－水混合物的溶解选择性与渗透选择性的关系陈俸荣，陈洪钫（天津大学化工系，天津３０００７２）关键词渗透蒸发，溶解选择性，渗透选择性，交联聚乙烯醇，乙二醇－水溶液１引言在渗透蒸发膜分离机理的研究中，存在着不同的观点［１－５...     

Separation of phenol from aqueous solution by membrane pervaporation using modified polyurethaneurea membranes

Hydroxy‐terminated polybutadiene‐based porous and nonporous polyurethaneurea membranes were prepared and used to study the phenol separation efficiency from dilute aqueous solution. The porosity was developed by incorporation of lithium chloride in polymer matrix with subsequent leaching of the same in hot water. The porous membrane showed higher phenol flux over that of nonporous membrane. Permeate containing about 97 wt % phenol was obtained from feed containing 7 wt % phenol, when pervaporation was carried out with porous polyurethaneurea membrane at 75°C. The activation energies for diffusion, permeation, and pervaporation were calculated from Arrhenius plots. From the activation energy values, it was observed that the pervaporation process became easier with increased phenol concentration in the feed and porosity of the membrane used. The membrane boundary resistance was observed to decrease with increase in temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1857–1865, 2006     

中空纤维膜渗透汽化过程中Dean涡强化传质的CFD模拟

建立了一个三维的弯管式中空纤维膜渗透汽化传质CFD模型,研究Dean涡对渗透汽化过程传质的影响,描述了膜内侧的浓度和速率变化情况,该模型与Leveque传质关联式具有良好的一致性。研究结果显示：弯管膜中Dean涡的存在能降低边界层传质阻力,总传质系数比直管膜提高了4倍;在不同的入口速率和浓度条件下,弯管膜内侧的壁面剪应力均大于直管膜。在膜阻力远小于边界层阻力的情况下,入口速率0.275 m·s^-1,水浓度10%（质量）时,弯管膜的渗透通量为12636 g·m^-2·h^-1,是直管膜的5倍。可见,弯管式中空纤维膜在渗透汽化过程中具有显著的强化传质效果。     

Extraction of 1-butanol from aqueous solutions by pervaporation

The extraction of 1-butanol from fermentation broths by pervaporation offers potential for use in biotechnology. Various membrane materials have been screened for their suitability for this process. Polydimethylsiloxane (PDMS) membranes gave the best results in terms of flux and selectivity, with large variations depending on their nature and preparation. Selectivity was further increased by including either organophilic adorbents (cyclodextrins, zeolites), or oleyl alcohol in dense PDMS membranes. The predominance of driving force (i.e. activity gradient) on pervaporation extraction performances was shown by a comparative study on different binary aqueous solutions of alcohols. Water flux remained practically constant while the alcohol flux was linearly related to its feed concentration. The conclusions obtained with binary mixtures were consistent with those obtained with two model ternary solutions; the influence of salt on 1-butanol permeability was negligible, whereas ethanol had a strong effect.     

Mass transfer of dilute 1,2‐dimethoxyethane aqueous solutions during pervaporation process

Pervaporation of 1,2‐dimethoxyethane (1,2‐DME) is evaluated by crosslinked oligosilylstyrene–poly(dimethylsiloxane) composite membranes. A low flow velocity of the feed solution (1.0 L/min), corresponding to a Reynolds number of 220, is used. The pervaporation models are developed by combining the resistance in series and solution–diffusion models. The effects of the boundary layer on the performance of pervaporation are estimated by comparing experimental and theoretical data. The permeation fluxes of 1,2‐DME and water fit very well with the calculated data from the models, but a deviation of the separation factor between the experimental and theoretical data is observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:2075–2084, 2006     

Vulcanized paper for separation of alcohol aqueous solutions by pervaporation

Paper membranes made from vulcanized cellulose were used for the pervaporation (PV) of aqueous solutions containing methanol, ethanol, and isopropanol. It was noted that the vulcanized cellulose paper membranes (VCPM) could effectively separate alcohol and water from the mixture solutions. To observe the effect of the separation of alcohol aqueous mixtures, the permeation behavior of water and alcohol was examined by means of the separation factor and the permeation flux. The values of the permeation flux in the ethanol/water mixtures were found to vary from 6.2 kg/m²h to 2.1 kg/m²h, as the concentration of ethanol increased from 8 to 87 wt %, and the separation factor (α) changed from α = 2.6 to 6.6, respectively. This showed that the VCPM enhanced the separation of water and alcohol. The highest value observed for the permeation flux was 11 kg/m²h at 87 wt % of methanol concentration and the separation factor at this condition was 4.1. It was shown also that an efficient separation was obtained in the isopropanol/water mixture with a separation factor of 16.6. The contact angles of alcohol/water droplets on the VCPM were measured as well as the wettability of the membrane. There was a tendency of decrease for the contact angle, as the alcohol concentration decreased. This suggested that the solvent wettability decreased in high alcohol concentrations. It was concluded that a high permeabilitty of water through the VCPM resulted in the separation of alcohols and water in the PV process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Membranes based on polyimide–polyaniline nanocomposites for pervaporation of organic mixtures

Polyimide–polyaniline nanocomposites were obtained by mixing poly{[4,4′‐bis(4″‐N‐phenoxy)diphenylsulfone]imide‐1,3‐bis(3,4‐dicarboxyphenoxy)benzene} (PI) and polyaniline (PANI) solutions in N‐methylpyrrolidone. These solutions were used for the preparation of homogeneous and composite membranes. Uniform distribution of PANI particles in the membranes, resulted from interactions between macromolecules, was confirmed by transmission electron microscopy. Membranes based on PI and PI–PANI were tested in pervaporation of binary organic mixtures: methanol/toluene and methanol/cyclohexane and showed a remarkable selectivity with respect to methanol. In both pervaporation processes, selectivity was improved in PANI‐containing membranes. Interactions between membrane polymers and liquid penetrants (methanol, toluene, and cyclohexane) were studied by measurements of surface tension, sorption, and pervaporation parameters. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A qualitative investigation on the importance of boundary layer in pervaporation separation of an aqueous organic reaction

The importance of boundary layer was investigated for the hydrolysis of ethyl acetate using a dense standard poly(vinyl alcohol) (PVA) membrane. A resistance in a series model approach was used to study the effect of a boundary layer for the permeation of aqueous organic mixtures involved in the study. The initial feed mixture consisted of 10% water (H₂O), 40% ethyl acetate (EA), 50% acetic acid (AA), and 0% ethanol (E) (all weight percentage basis). The experiments were conducted at 65°C. The amount of all species in the feed reservoir was found to decrease with time. Selectivity calculations based on a resistance in the series model approach indicates that the boundary layer contributes to selective permeation of aqueous organic compounds. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2361–2369, 1998