PSF支撑层结构对PDMS复合膜渗透汽化性能的影响

以4种不同结构的聚砜(PSF)作为支撑层,制备PDMS/PSF渗透汽化复合膜,考察其用于乙醇/水体系的分离性能,以研究支撑层结构对渗透汽化复合膜分离性能的影响。采用SEM和EDX分析复合膜表层结构,结果表明,支撑层结构几乎不影响复合膜的选择性,但对膜通量有较大影响,特别是支撑层的表面结构对复合膜性能的影响比断面结构更明显。     

芳烃优先透过的渗透汽化复合膜的制备及分离性能研究

采用紫外光接枝填充聚合技术,以非对称聚丙烯腈(PAN)超滤膜为底膜,聚乙二醇甲醚甲基丙烯酸酯(MePEO300MA)为大分子单体,制备了芳烃优先透过的渗透汽化复合膜。考察了单体浓度和紫外光照射反应时间对复合膜甲苯/正庚烷渗透汽化分离性能的影响,并对复合膜降低石脑油芳烃含量,优化乙烯裂解原料进行了初步探索。研究结果表明,复合膜对甲苯质量分数为20%的甲苯/正庚烷混合物(80℃)的分离系数达到5.6,渗透通量为2.47 kg/(m2.h);当切割比为20%时,石脑油的芳烃质量分数由7.52%降至4.11%,降低了45%,初步说明渗透汽化复合膜在降低石脑油的芳烃含量,优化乙烯裂解原料方面的应用前景。     

硅溶胶补强PDMS-PA复合膜的性能

以疏水纳米二氧化硅溶胶作硅橡胶的补强材料,制成了硅橡胶-聚酰胺(PDMS-PA)复合膜;用扫描电镜观察了其断面形态,考察了复合膜对醇-水溶液的渗透蒸发分离效果及耐用性,并与气相法白炭黑补强PDMS-PA复合膜进行了比较.结果表明,与气相法白炭黑补强PDMS-PA复合膜相比,硅溶胶补强的PDMS-PA复合膜的PDMS皮层和PA支撑层之间的结合更紧密,但分离因子和渗透通量下降.在相同条件下进行醇-水分离实验后,气相法白炭黑补强PDMS-PA复合膜出现PDMS皮层与PA支撑层分离现象;而硅溶胶补强PDMS-PA复合膜的PDMS皮层与PA支撑层结合完好.表明用硅溶胶作107硅橡胶的补强填料时能在PDMS-PA复合膜的渗透汽化性能略有下降的情况下改善PDMS皮层与PA支撑层之间的结合,提高复合膜的耐用性,使其具有工业使用价值.     

藻朊酸钠渗透汽化膜分离有机液／水混合物

研究了藻朊酸钠均质膜及藻朊酸钠／酸丙烯腈复合膜的渗透汽化特性。发现它们对甲醇、乙醇、异丙醇、丙酮、四氢呋喃（ＴＨＦ）、二氧六环、丙三醇等有机溶剂与水的混合望远镜水优选 透过，其渗透通量与选择分离系数都非常高。复合膜与均质膜相比，通量成倍增加，除甲醇／水体系外，对其他体系的分离系数不大，对二氧六环／水体系的分离系数复合膜更高。三种藻朊酸钠样品对乙醇／水，二氧六环／水的透过分离性能有所差异，对此，从膜     

支撑层结构对PTFE-PDMS复合膜渗透汽化性能的影响

以不同结构的聚四氟乙烯(PTFE)平板膜为支撑层、聚二甲基硅氧烷(PDMS)为活性层,通过表面涂覆方法制备PTFE-PDMS复合膜,并用于渗透汽化过程,以实现乙醇-水混合溶液的分离;研究了支撑层结构及制膜参数对其分离性能的影响。结果表明,支撑层结构对复合膜分离因子几乎无影响,对孔径大孔隙率高的支撑层,制膜时,PDMS聚合物向支撑层中渗入过多会使复合膜的渗透通量降低。PDMS聚合物向支撑层渗透形成的过渡层是复合膜传质阻力的重要部分,且过渡层厚,复合膜的耐溶胀性好。综合考虑渗透通量及分离因子,复合膜优化制备条件是交联剂正硅酸乙酯的质量分数4%,交联温度80℃,交联时间为5 h。     

双组分加成型硅橡胶膜制备及其渗透汽化分离碳酸二甲酯/甲醇

制备了一系列双组分加成型硅橡胶(PDMS)膜及ZSM-5沸石填充PDMS复合膜,用于渗透汽化法分离甲醇,碳酸二甲酯混合物,考察了C6-530双组分硅橡胶A/B组分比例、后处理温度、沸石填充浓度、操作温度对渗透汽化分离性能的影响.     

纳米白炭黑填充硅橡胶复合膜的制备与渗透汽化分离性能

制备以聚酯(PET)为支撑层,白炭黑填充的聚二甲基硅氧烷(PDMS107)为皮层的硅橡胶复合膜,并以乙醇水物系为料液,对比分析白炭黑增强硅橡胶复合膜的渗透蒸发分离性能,分离因子比空白膜有所提高,在乙醇浓度为3%～5%时,分离因子可达16.09,渗透通量为75.39 g/m2·h;测定填充白炭黑硅橡胶复合膜的拉伸强度,结果表明:拉伸强度可达1.828 MPa,相当于空白膜(0.368 MPa)的5倍.     

支撑层结构对醇类渗透汽化过程的影响

研究了硅橡胶复合膜的支撑层结构对一系列不同分子体积的醇类的低浓度水溶液的渗透汽化过程的传质影响。研究发现支撑层对一系列醇的传质阻力的影响不仅取决于它的几何结构,也与支撑层的化学性质有关。聚二甲基硅氧烷-聚偏氟乙烯(PDMS-PVDF)复合膜与聚二甲基硅氧烷-聚酰胺(PDMS-PA)复合膜相比,对醇类化合物有着更好的渗透汽化表现。在30℃下醇类多组分体系通过PDMS-PVDF复合膜的总渗透通量为449.041 7 g/(m2.h),高于相同条件下PDMS-PA膜。通过选择合适的支撑层材料,改变支撑层的几何结构和疏水性,可以优化醇类组分的膜传质过程。     

利用膜分离技术回收正丁醇/水混合液的工艺研究

研究了聚乙烯醇（PVA）／聚丙烯腈（PAN）、海藻酸钠（SA）／PAN复合膜及海藻酸钠／醋酸纤维素（CA）共混膜等五种膜的渗透汽化特性,发现它们对正丁醇／水的混合液均表现为水优先透过,其渗透通量与选择分离系数都很高。并初步确定了正丁醇／水混合液渗透汽化分离的工业生产操作条件。     

PVA复合膜的渗透汽化性能研究：（Ⅰ）操作条件和长期运行的影响

本文研究了以ＰＡＮ膜为支撑层的ＰＶＡ复合膜分离醇水溶液的性能。着眼于工业应用，揭示了渗透汽化操作条件对分离性能的影响，展示了长期运行时的分离性能。结果表明，ＰＶＡ复合膜具有高渗透通量和优异分离率，长期运行性能稳定。     

Influence of support layer and PDMS coating conditions on composite membrane performance for ethanol/water separation by pervaporation

A systematic study was performed on the combination of support properties and polydimethylsiloxane (PDMS) coating conditions for the lab‐scale preparation of a defect‐free, thin film composite membrane for organophilic pervaporation. Support layers having comparable surface porosities were prepared from three polymers with different chemical composition (PVDF, PSF, PI). Their exact role on the deposition of the PDMS coating (i.e., wetting and intrusion) and the final membrane performance (i.e., effect on mass transfer of the permeants) was studied. The crosslinking behavior of dilute PDMS solutions was studied by viscosity measurements to optimize the coating layer thickness, support intrusion and wetting. It was found essential to pre‐crosslink the PDMS solution for a certain time prior to the coating. Dip time for coating the PDMS solution on the supports was varied by using automated dip coating machine. The performance of the synthesized membranes was tested in the separation of ethanol/water mixtures by pervaporation. Both flux and selectivity of the membranes were clearly influenced by the support layer. Resistance of the support layers increased by increasing the polymer concentration in the casting solutions of the supports. Increasing the dip time of the PDMS coating solution led to increased selectivity of the composite membranes. Scanning Electron Microscopy analysis of the composite membranes showed that this leads to a minor increase in the thickness of the PDMS top layer. Top layer thickness increased linearly with the square root of the dip time (t^0.5) at a constant withdrawal speed of the support. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43670.     

Surface modification of nanocomposite ceramic membranes by PDMS for condensable hydrocarbons separation

PDMS/ceramic nanocomposite membranes were fabricated via dip-coating method. Tubular porous nanocomposite ceramic supports were used as membrane substrates and polydimethylsiloxane was applied as a top active layer. The hybrid membranes were characterized morphologically by scanning electron microscopy (SEM) and their gas transport properties were measured using single gas permeation (butane and hydrogen) at ambient temperature and different pressures. SEM micrographs confirmed the penetration of polymeric layer into ceramic support pores at low concentrations of PDMS solution. Experimental results clearly indicated that the undesirable penetration during the dip-coating stage could be avoided by increasing the concentration of PDMS coating solution. This led to the formation of a uniform and dense coating layer without penetration into pores of the support. These hybrid membranes showed higher permeability combined to a suitable selectivity in comparison with dense homogeneous PDMS membrane. In addition, at low pressures, the high selectivity of PDMS/ceramic nanocomposite membranes for condensable hydrocarbons separation revealed that the dominant mechanism is solution-diffusion.     

ZSM-5填充PDMS复合膜渗透蒸发分离乙醛水溶液(英文)

Hydrophobic ZSM-5 zeolite filled polydimethylsiloxane(PDMS) composite membranes with Nylon micro-filtration membrane as the support layer were prepared to separate acetaldehyde from its aqueous solution.The composite membranes were characterized by Fourier transform infrared spectroscopy and X-ray diffraction.Their structural morphology and thermal stability were also examined.The swelling study showed that the composite membranes presented higher degree of swelling in aqueous solution of acetaldehyde than in pure water at 25 C,suggesting that the membranes have stronger sorption capacity in acetaldehyde solution.The effects of ZSM-5 filling content and acetaldehyde concentration on pervaporation performance of composite membranes were investigated.The permeation experiments at different temperatures showed that both selectivity and permeation flux of composite membranes increased with temperature.With 5%ZSM-5-PDMS/Nylon membrane at acetaldehyde mass concentration of 8% and 25℃,the separation factor of acetaldehyde/water achieved 35 and the permeation flux was 233.3 g·m-2·h-1.     

Concentration of Dilute Acetone-Water Solutions Using Pervaporation

Abstract

The separation of acetone-water mixtures by pervaporation has been studied. Four membranes were evaluated: a silicone composite (SC) membrane, a polydi-methylsiloxane (PDMS) membrane, a polymethoxysiloxane (PMS), and a polyether-block-polyamide copolymer (PEBA) membrane. The silicone composite membrane exhibited a higher flux and selectivity than any of the other membranes studied. At a feed temperature of 50°C, a permeate-side pressure of 1 torr, and a feed concentration of 5.0%, the silicone composite membrane had a flux of 1.1 kg/m²·h and a selectivity of 50. The effects of temperature and permeate-side pressure on membrane transport were studied using the SC membrane. An increase in temperature increased the flux exponentially, but had little effect on selectivity. An analysis of the data shows that the trend agrees quite well with an Arrhenius-type relationship. As the permeate-side pressure increased, the flux decreased in a sigmoidal fashion over the range evaluated. Selectivity did not change significantly over the lower portion of the pressure range studied. The effect of feed concentration on flux and selectivity was also investigated.     

硅橡胶复合膜渗透汽化分离硫/汽油混合物

Worldwide environment has resulted in a limit on the sulfur content of gasoline. It is urgent to investigate the desulfurization of gasoline. The polydimethylsiloxane (PDMS)/polyetherimide (PEI) composite membranes were prepared by casting a PDMS solution onto porous PEI substrates and characterized by scanning electron microscope (SEM). The membranes were used for sulfur removal from gasoline by pervaporation. The effects of feed temperature, sulfur content in the feed and PDMS layer thickness on membrane performance were investigated, and an activation energy of permeation was obtained. Experimental results indicated that higher feed temperature yielded higher total flux and lower sulfur enrichment factor. The total flux varied little with the increase of sulfur content in the feed, but the sulfur enrichment factor first increased with the amount of thiophene added into the gasoline, and then the variation was little. The increase of PDMS layer thickness resulted in a smaller flux but a larger sulfur enrichment factor. The result indicates that the PDMS/PEI composite membranes are promising for desulfurization by pervaporation.     

有机硅烷交联PDMS/陶瓷复合膜的制备及渗透汽化汽油脱硫性能

采用有机硅烷γ-氨丙基三甲氧基硅氧烷（APTMS）,对聚二甲基硅氧烷（PDMS）进行交联改性,以ZrO₂/Al₂O₃陶瓷复合膜为支撑体,制备了一系列有机硅烷交联的PDMS/陶瓷复合膜。通过扫描电镜（SEM）、傅里叶红外光谱（FTIR）、热重分析（TGA）对改性效果和膜结构进行了表征。将所制备的PDMS/陶瓷复合膜应用于渗透汽化脱除模拟汽油中的有机硫化物（噻吩）,考察了交联剂APTMS含量、操作温度、料液含硫量等因素对复合膜渗透汽化脱硫性能的影响。实验结果表明,有机硅烷交联的PDMS膜相比于传统正硅酸乙酯（TEOS）交联的PDMS膜,通量和硫富集因子均有所提高。随着进料温度和原料液中硫含量的升高,膜的渗透通量均增大,而硫富集因子均减小。当APTMS质量分数为15%、进料温度为25℃、噻吩质量浓度为100mg/kg时,渗透通量为0.46 kg/（m²·h）,硫富集因子达到3.5。     

A new technique for preparation of PDMS/ceramic nanocomposite membrane for gaseous hydrocarbons separation

A novel composite membrane using polydimethylsiloxane (PDMS) as a top active layer and ceramic nanocomposite as the support layer was developed for the gaseous hydrocarbons separation. For the fabrication of hybrid membranes, nanocomposite technology applied for manufacturing ceramic supports with controllable microstructures. Also, a new method was used for coating a uniform and no penetrated polymeric layer. Top layer of ceramic support with nanocomposite microstructures was fabricated using 5 wt % α‐Al₂O₃‐SiO₂ bidispersed suspensions with optimum weight fraction of second phase (SiO₂) based on the fractional collision frequency theory. PDMS selective layer was coated on the outer surface of the porous ceramic nanocomposite support by dip‐coating method. In this respect, the effect of several parameters such as pretreatment temperature, PDMS solution concentration, and number of coated polymeric layers on prepared layers morphology and hybrid membrane performance in the separation of condensable hydrocarbons (iso and n‐butane) from hydrogen were investigated. The results showed that the membranes fabricated at 140°C as pretreatment temperature and three polymeric layers by 7, 15, and 15 wt % PDMS concentration, respectively, had a high selectivity (>25 at 2 bar)) in C₄H₁₀/H₂ separation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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     

PDMS/ZIF-8 coating polymeric hollow fiber substrate for alcohol permselective pervaporation membranes

In order to develop high performance composite membranes for alcohol permselective pervaporation (PV), poly (dimethylsiloxane)/ZIF-8 (PDMS/ZIF-8) coated polymeric hollow fiber membranes were studied in this research. First, PDMS was used for the active layer, and Torlon®, PVDF, Ultem®, and Matrimid® with different porosity were used as support layer for fabrication of hollow fiber composite membranes. The performance of the membranes varied with different hollow fiber substrates was investigated. Pure gas permeance of the hollow fiber was tested to investigate the pore size of all fibers. The effect of support layer on the mass transfer in hydrophobic PV composite membrane was investigated. The results show that proper porosity and pore diameter of the support are demanded to minimize the Knudsen effect. Based on the result, ZIF-8 was introduced to prepare more selective separation layer, in order to improve the PV performance. The PDMS/ZIF-8/Torlon® membrane had a separation factor of 8.9 and a total flux of 847 g·m^-2·h^-1. This hollow fiber PDMS/ZIF-8/Torlon® composite membrane has a great potential in the industrial application.     

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。