细菌纤维素膜渗透汽化分离二元有机物水溶液

采用动静结合的方式制备出了细菌纤维素膜。以乙醇水溶液、丙酮水溶液、乙酸水溶液为研究对象,研究了渗细菌纤维素膜的吸附性能,并讨论了透汽化过程中原料液浓度、温度对分离效果的影响及渗透汽化过程中可能的分离机理。结果表明,细菌纤维素膜能够优先透水,在渗透汽化分离乙醇和丙酮时,渗透通量随浓度的上升呈下降的趋势,温度对渗透通量的影响基本符合Arrhenius方程渗透汽化分离二者时,分离因子随浓度的增加先增加后减小。渗透汽化分离乙酸时,渗透通量随浓度的上升呈先上升后下降的趋势,分离因子变化不明显,温度对渗透通量的影响偏离Arrhenius方程较明显。     

细菌纤维素膜渗透汽化分离二元有机物水溶液

采用动静结合的方式制备出了细菌纤维素膜。以乙醇水溶液、丙酮水溶液、乙酸水溶液为研究对象,研究了渗细菌纤维素膜的吸附性能,并讨论了透汽化过程中原料液浓度、温度对分离效果的影响及渗透汽化过程中可能的分离机理。结果表明,细菌纤维素膜能够优先透水,在渗透汽化分离乙醇和丙酮时,渗透通量随浓度的上升呈下降的趋势,温度对渗透通量的影响基本符合Arrhenius方程渗透汽化分离二者时,分离因子随浓度的增加先增加后减小。渗透汽化分离乙酸时,渗透通量随浓度的上升呈先上升后下降的趋势,分离因子变化不明显,温度对渗透通量的影响偏离Arrhenius方程较明显。     

全硅沸石/聚二甲基硅氧烷渗透汽化膜制备及分离性能

考察了全硅沸石/聚二甲基硅氧烷(PDMS)渗透汽化均质膜制膜液中国液比(质量比)对渗透汽化膜性能的影响,利用均匀设计优化方法对交联时间、交联温度、全硅沸石填充鼍和PDMS中b胶量等对膜分离因子的影响进行了研究,制备了对丁醇分离性能较高的渗透汽化均质膜.50℃下,分离原料液质量分数为1.6%的丙酮-丁醇-乙醇-水溶液时,...     

模拟的发酵液组分对聚二甲基硅氧烷/陶瓷复合膜渗透汽化性能的影响

对所制备的聚二甲基硅氧烷（PDMS）/陶瓷复合膜进行了渗透汽化性能表征。通过在乙醇-水混合体系中添加不同的模拟发酵液组分;如葡萄糖（多羟基醛）、甘油（多元醇）、丁二酸（有机酸）、KCl（无机盐）;考察了各组分对复合膜渗透汽化性能的影响。研究发现：在333 K下;在乙醇浓度为65 g·L-1的混合物中添加不同浓度的第三组分;有机添加物对膜的渗透汽化性能没有明显影响;而无机盐的加入使膜的分离因子稍有提高。所制备的PDMS/陶瓷复合膜;在上述渗透汽化过程中表现出良好的稳定性和对乙醇的优先选择性;渗透通量和分离因子（醇/水）分别在4.5～4.7 kg·m^-2·h^-1、8.3～10.3之间。     

PDMS/PEI膜渗透汽化分离正丁醇/乙醇/水的性能及渗透通量关联模型研究

采用聚二甲基硅氧烷/聚醚酰亚胺(PDMS/PEI)膜渗透汽化分离正丁醇/乙醇/水体系,考察进料温度、进料组成等条件对膜渗透汽化分离性能的影响;采用Arrhenius型半经验渗透通量关联模型描述PDMS-PEI膜分离正丁醇/乙醇/水体系膜通量变化。结果表明,当原料液中正丁醇质量分数分别为4.0%、4.5%和5.0%时,正丁醇/乙醇/水三元体系中正丁醇渗透通量分别至少提高14.2%、17.7%和23.4%。渗透通量关联模型能较好地描述PDMS-PEI膜分离正丁醇/乙醇/水体系膜渗透通量变化。     

PDMS/ZSM-5膜的制备及渗透汽化分离水中乙酸正丁酯和乙酸乙酯

为探究出适合分离水中的乙酸正丁酯和乙酸乙酯的新型渗透汽化膜材料,选用沸石ZSM-5 对聚二甲基硅氧烷(PDMS)材料进行填充改性,以聚偏氟乙烯(PVDF)为支撑层,采用刮涂法制备PDMS/ZSM-5/PVDF复合膜渗透汽化分离水中的乙酸正丁酯和乙酸乙酯。采用SEM、接触角测量仪、FTIR、TGA和XRD等对膜材料物理化学性能进行表征,考察了膜材料的溶胀行为及渗透汽化性能。结果表明,ZSM-5在 PDMS 膜中分散均匀,且没有发生化学作用,并提高了膜材料的疏水性和热稳定性。随着ZSM-5添加量的增加,膜在乙酸正丁酯和乙酸乙酯的溶胀度和待分离组分在膜材料中的扩散速率不断增加。随着进料浓度和温度的增加,渗透通量不断增大,分离因子先增大后减小。随着ZSM-5在PDMS/ZSM-5/PVDF复合膜中含量的增加,总渗透通量增加,而分离因子呈现先增加后减小的趋势。当添加量为10%（质量）时,分离因子达到最大值。对于乙酸正丁酯/水体系,渗透通量和分离因子最大值分别为319 g·m ^-2·h ^-1和131;而对于乙酸乙酯/水体系,渗透通量和分离因子最大值分别为1385 g·m ^-2·h ^-1和121。     

响应面优化法在PDMS/PVDF膜制膜条件优化中的应用

用响应面优化法优化了乙烯基封端PDMS/PVDF渗透汽化透醇膜的制膜条件,研究了硅橡胶浓度、B/A质量比、交联温度和交联时间对膜性能的影响,拟合了分离因子、渗透通量与四因素之间的回归方程,并用方差分析法考察了四因素的主效应、二次效应以及相互作用效应对复合膜的分离因子与渗透通量的影响。研究发现,硅橡胶浓度对膜的分离因子与渗透通量的影响最为显著,交联时间对分离因子几乎没有影响。通过对回归方程的优化分析得知,在料液乙醇浓度为10%(wt),操作温度40℃条件下,当硅橡胶浓度为93%(wt),B/A质量比为0.08,交联温度为100℃,交联时间为13.83 h时,膜的综合分离性能达到最佳,此时分离因子与渗透通量预测值分别为9.47、77.57 g(m2 h)1,渗透侧乙醇浓度达到51.3%(wt)。回归方程的验证实验结果表明,回归方程的估计值与实验值较为吻合,可用于乙烯基封端的PDMS/PVDF复合膜的渗透汽化性能的预测与优化。     

有机/无机杂化渗透汽化优先透醇膜研究进展

渗透汽化优先透醇膜分离技术可有效解决燃料乙醇和丁醇生产中发酵产率较低的瓶颈问题,受到广泛关注。膜材料的选择与改性以及膜结构的构建是提高透醇性能的关键。有机/无机杂化膜可以实现有机和无机材料的优势互补,被认为是未来分离膜领域最重要的发展方向之一。本文扼要回顾了用于优先透醇渗透汽化分离的有机无机杂化材料,结合本文作者课题组的研究工作,重点阐述了杂化粒子的结构、粒径、界面相容性、纳微分散、负载量等因素对渗透汽化传递过程的作用机制,进一步对近年来发展的成膜新方法进行了总结。在此基础上,提出今后有机/无机杂化渗透汽化优先透醇膜研究的主要方向是发展新型纳米级、超疏水并与有机聚合物具有高度界面相容性的无机粒子,以及构建高负载量的纳微结构与超亲醇表面。     

有机硅烷改性PDMS/Silicalite渗透汽化杂化膜制备及其分离性能

采用硅烷偶联剂对全硅沸石Silicalite-1进行表面改性,以聚二甲基硅氧烷(PDMS)为基体,制备了渗透汽化PDMS/Silicalite杂化膜. 用FT-IR, TGA等对改性的效果和杂化膜的热稳定性能进行了表征,并以低浓度乙醇/水体系为研究对象,以渗透通量和分离因子为评价指标,考察了料液组成、进料温度、循环流速、膜下游侧真空度等因素对改性杂化膜分离性能的影响. 结果表明,硅烷改性沸石所制杂化膜对低浓度乙醇/水体系的分离因子比空白膜和未改性杂化膜分别提高136%和45%. 随料液中乙醇浓度从5%增加到69%,膜分离因子从22降低到7,而其他因素对膜的选择性影响较小.     

丙酮、乙醇对丁醇渗透汽化性能的影响

考察了全硅沸石silicalite-1对丁醇-水、丙酮-水、乙醇-水、丙酮-丁醇-水、乙醇-丁醇-水5种体系中各溶剂的吸附作用。采用自制的silicalite-1/硅橡胶杂化渗透汽化透醇膜,研究了温度对丙酮、丁醇、乙醇分离性能的影响以及不同分离温度下丙酮、乙醇的浓度对丁醇、水渗透汽化性能的影响,结果表明丙酮和乙醇的存在会促进丁醇的透膜性。     

碳分子筛填充硅橡胶膜用于渗透蒸发分离稀醋酸-水溶液

From the reference[1] it is known that the addition of silicalite-1 in silicone rubber membranes results in an increase of both flux and selectivity for alcohol in the separation of alcohol/water by pervaporation.In order to enhance performance of pervaporation toward the aqueous solution of acetic acid,incorporation of carbon molecular sieve(CMS)into a PDMS membrane was investigated. CMS is widely used in adsorption processes because of its high selectivity toward certain compounds[2]. It was assumed that the flux and selectivity of pure PDMS membrane could be enhanced owing to the preferential adsorption of CMS to organics.CMS content in the membrane and several important pervaporation operation parameters, including feed concentration of acetic acid, and feed temperature, were investigated.     

Preparation and characterization of Silicalite‐1/PDMS surface sieving pervaporation membrane for separation of ethanol/water mixture

To improve the pervaporation performance of Silicalite‐1/PDMS composite membrane by adding a small amount of Silicalite‐1 zeolite, novel Silicalite‐1/PDMS surface sieving membranes (SSMs) were prepared by attaching Silicalite‐1 particles on the PDMS membrane surface. The obtained membranes and traditional mixed‐matrix membranes (MMMs) were characterized by SEM, XRD, TGA, FT‐IR, and pervaporation separation of ethanol–water mixture. Effects of Silicalite‐1 particles content, feed temperatures, and feed compositions on the separation performance were discussed. From the cross‐section view SEM images of SSMs, a two‐layer structure was observed. The thickness of the Silicalite‐1 layer was about 300 nm to 2 μm. The TGA analysis indicates that the zeolite concentration in 3 wt % SSM is lower than 10 wt % MMMs. In the ethanol/water pervaporation experiment, the separation factor of Silicalite‐1/PDMS SSMs increased considerably compared with pure PDMS membrane. When the suspensions concentrations of Silicalite‐1 particles reached 3 wt %, the separation factor was about 217% increase over pure PDMS membrane and 52.9% increase over 10 wt % Silicalite‐1/PDMS MMMs. As the ethanol concentration in the feed increases, the separation factor of SSMs increases, whereas permeation flux decreases. At the same time, with increasing operating temperature, the permeation flux of SSMs increased. The stability of SSMs at high temperature is better than the traditional MMMs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42460.     

Pervaporation of Water/Ethanol Mixtures by an Aromatic Polyetherimide Membrane

Abstract

The pervaporation of water/ethanol mixtures through an aromatic polyetherimide membrane was attempted. The membrane was laboratory prepared using the solution casting technique. The sorption characteristics in relation to pervaporation were also studied. It was found that the preferential sorption was altered when the liquid composition was changed, whereas the water component permeated through the membrane preferentially over the whole range of feed mixture compositions. The experimental results were analyzed in terms of sorption ratio and permeation ratio to characterize nonideality of sorption and pervaporation. The effects of some operating parameters, including temperature, feed concentration, and permeate pressure, on the pervaporation performance were also investigated.     

RECOVERY OF ACETIC ACID OVER WATER BY PERVAPORATION WITH A COMBINATION OF HYDROPHOBIC IONIC LIQUIDS

The present work considers the application of an integrated pervaporation process to improve the pervaporation performance of acetic acid over water. This integrated pervaporation process was based on a plain PDMS membrane with a hydrophobic ionic liquid composed of a heterocyclic cation and [PF₆]^- anions. The hydrophobic ionic liquid was introduced as the third phase between the aqueous phase and the plain PDMS membrane for improving mass-transfer of acetic acid from its aqueous matrix to the PDMS membrane. The primary results indicated that the ionic liquid as an extractant prior to pervaporation was favorable for improving the permeate selectivity and the permeate flux of acetic acid compared with using only a plain PDMS membrane. This performance could be attributed to the acetic acid concentrated and the water molecules rejected by ionic liquid prior to pervaporation. Extraction of a real effluent containing acetic acid from an antibiotic pharmaceutical plant was carried out using the above integrated pervaporation, and the results imply that this integrated pervaporation process could be scaled up for recovering acetic acids over its water-rich effluents.     

Pervaporative Dehydration of Binary Ethanol/Water and Ternary Ethanol/Water/Methanol Mixtures Using a Methylated Silica Membrane: A Mechanistic Approach

The pervaporation properties of a methylated-silica membrane were studied on binary ethanol/water and ternary ethanol/water/methanol mixtures. The aim was to acquire a better understanding of the pervaporation mechanisms by studying the effects of feed temperature, permeate pressure, and feed composition on molecular transport. Emphasis was placed on the role of competitive adsorption and dragging and blocking effects between the components in the context of the adsorption-diffusion model. The results show the potential of the membrane for the coupled removal of water and methanol from bioethanol. This attractive application for process intensification was suggested for the first time in this paper.     

RECOVERY OF ACETIC ACID OVER WATER BY PERVAPORATION WITH A COMBINATION OF HYDROPHOBIC IONIC LIQUIDS

The present work considers the application of an integrated pervaporation process to improve the pervaporation performance of acetic acid over water. This integrated pervaporation process was based on a plain PDMS membrane with a hydrophobic ionic liquid composed of a heterocyclic cation and [PF₆]^? anions. The hydrophobic ionic liquid was introduced as the third phase between the aqueous phase and the plain PDMS membrane for improving mass-transfer of acetic acid from its aqueous matrix to the PDMS membrane. The primary results indicated that the ionic liquid as an extractant prior to pervaporation was favorable for improving the permeate selectivity and the permeate flux of acetic acid compared with using only a plain PDMS membrane. This performance could be attributed to the acetic acid concentrated and the water molecules rejected by ionic liquid prior to pervaporation. Extraction of a real effluent containing acetic acid from an antibiotic pharmaceutical plant was carried out using the above integrated pervaporation, and the results imply that this integrated pervaporation process could be scaled up for recovering acetic acids over its water-rich effluents.     

Acetic acid/water separation by pervaporation with silica filled PDMS membrane

Silica‐filled polydimethylsiloxane (PDMS) composite membranes are prepared on a polytetrafluoroethylene support structure. The structure and the performance of the membranes are characterized by scanning electron microscope, Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetry. The pervaporation process for acetic/water separation is performed within the PDMS membranes. The vulcanization temperature was found to have a great influence on the separation performance of the membrane. The addition of silica can significantly improve the pervaporation flux and enhance the thermal stability of the membrane. With an increase in the feed temperature, selectivity decreases and permeation flux increases. Performed with a pure PDMS membrane vulcanized at 30°C, the separation factor at first will increase, then decrease when the feed flow rate was increased from 14 to 38 L · h^?1. The maximum separation factor is achieved when the feed flow rate is 26 L · h^?1. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Modified polydimethylsiloxane/polystyrene blended IPN pervaporation membrane for ethanol/water separation

In this article a modified polydimethylsiloxane (PDMS) blended polystyrene (PS) interpenetrating polymer network (IPN) membranes supported by Teflon (polytetrafluoroethylene) ultrafiltration membrane were prepared for the separation of ethanol in water by pervaporation application. The relationship between the surface characteristics of the surface‐modified PDMS membranes and their permselectivity for aqueous ethanol solutions by pervaporation are discussed. The IPN supported membranes were prepared by sequential IPN technique. The IPN supported membrane were tested for the separation performance on 10 wt % ethanol in water and were characterized by evaluating their mechanical properties, swelling behavior, density, and degree of crosslinking. The results indicated that separation performance, mechanical properties, density, and the percentage of swelling of IPN membranes were influenced by degree of crosslink density. Depending on the feed temperature, the supported membranes had separation factors between 2.03 and 6.00 and permeation rates between 81.66 and 144.03 g m^?2 h^?1. For the azeotropic water–ethanol mixture (10 wt % ethanol), the supported membrane had at 30°C a separation factor of 6.00 and a permeation rate of 85 g m^?2 h^?1. Compared to the PDMS supported membranes, the PDMS/PS IPN supported blend membrane ones had a higher selectivity but a somewhat lower permeability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Dehydration of acetic acid/water mixtures by pervaporation with a modified poly(4-methyl-1-pentene) membrane

The dehydration of acetic acid/water mixtures by pervaporation with a EVA/TPX membrane has been studied. The membrane exhibited water selectivity during all process runs. Investigations were focused on the effects of heat treatment temperature on membrane formation, membrane thickness, feed solution concentration, EVA content, and feed solution temperature. Compared with pure TPX membrane, the EVA/TPX blend membrane effectively improved the pervaporation performances. The permeation rate decreases with increasing heat treatment temperature during the membrane formation. Optimum pervaporation results were obtained by EVA/TPX membrane with 12.5 wt % EVA content, giving a separation factor of 606 and permeation rate of 215 g/m²h.