沸石填充硅橡胶渗透汽化膜的制备及其优先透醇性能研究

由ZSM-5沸石和聚二甲基硅氧烷(PDMS)制备超薄沸石填充PDMS复合膜,考察沸石填充量、沸石结构中硅铝比和操作温度对沸石填充硅橡胶膜渗透汽化性能的影响。结果表明,超薄复合膜的制备可以改善渗透通量小的缺陷。沸石填充量30%时分离因子最大;具有相同填充量的PDMS膜,硅铝比较大的填充膜,其分离因子和渗透通量均较高;随着操作温度的升高,复合膜分离因子先升高后降低,在50℃达到最大值,其渗透通量呈升高趋势。     

沸石填充硅橡胶渗透汽化膜的制备及其优先透醇性能研究

由ZSM-5沸石和聚二甲基硅氧烷(PDMS)制备超薄沸石填充PDMS复合膜,考察沸石填充量、沸石结构中硅铝比和操作温度对沸石填充硅橡胶膜渗透汽化性能的影响。结果表明,超薄复合膜的制备可以改善渗透通量小的缺陷。沸石填充量30%时分离因子最大;具有相同填充量的PDMS膜,硅铝比较大的填充膜,其分离因子和渗透通量均较高;随着操作温度的升高,复合膜分离因子先升高后降低,在50℃达到最大值,其渗透通量呈升高趋势。     

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.     

PTFE对PDMS复合膜在低浓度有机物水溶液中渗透汽化性能的影响

制备了聚四氟乙烯（PTFE）超细粉体填充聚二甲基硅氧烷（PDMS）复合膜,通过扫描电子显微镜、傅里叶变换红外光谱仪、热失重分析仪等测试仪器对复合膜进行了表征,利用低浓度有机物（乙醇、丙酮、正丙醇）水溶液体系进行渗透汽化,并由单组分溶解实验计算了有机物（乙醇、丙酮、正丙醇）在复合膜中的溶解度。结果表明,PTFE含量由0增加至10 %（质量分数,下同）时, 复合膜的表面积及热稳定性得到了提高,有机物乙醇、丙酮、正丙醇在复合膜中的溶解度分别由0.0923、0.1589和0.2691 g/g提高至0.0991、0.1678和0.2773 g/g;加入PTFE后提高了复合膜的渗透汽化性能。     

PTFE-PDMS/PVDF复合膜制备及其渗透汽化性能

制备了以聚偏氟乙烯PVDF超滤膜为底膜的聚四氟乙烯PTFE超细粉体填充聚二甲基硅氧烷PDMS复合膜,并用于氯仿水溶液体系的渗透汽化。采用SEM和接触角分析研究了膜结构及表面性能。研究了PTFE:PDMS质量比、料液流速、料液浓度对渗透汽化性能的影响;采用串联阻力模型分析了渗透汽化氯仿水溶液的传质过程。研究表明,填充PTFE提高了PDMS膜渗透汽化性能;流量大于200 mL min 1时渗透汽化传质阻力主要由膜阻力控制;在流速低于200 mL min 1时,浓差极化产生的氯仿传质边界层阻力最大可达膜阻力的29倍。     

白炭黑填充PDMS/PVDF复合膜的纳滤分离性能及传质特性

将纳米级白炭黑填充于PDMS制备了白炭黑填充PDMS/PVDF复合膜,采用红外(FT-IR)、热失重(TGA)和接触角(CA)等方法对填充复合膜进行了分析和表征,并采用纳滤的方法系统研究了复合膜对大豆油/己烷混合油的分离性能。结果表明,白炭黑填充能有效促进PDMS的交联,提高PDMS的疏水性、热失重温度以及对溶剂的稳定性;白炭黑填充量增加使复合膜渗透通量降低,但截留率从96%提高到98%;随溶液浓度增加,渗透通量和截留率同时降低;随温度的升高,渗透通量上升,截留率降低。大豆油和己烷在膜中的传质特性可用不完全的溶解-扩散模型描述,溶液渗透压实验值与计算值符合较好。     

SiO_2/PDMS/PVDF复合膜渗透蒸发回收煤化工废水中酚

采用PVDF中空纤维为基膜,以Si O_2填充PDMS溶液为涂覆液,进行动态负压涂覆,制备Si O_2/PDMS/PVDF复合膜材料,回收处理煤化工废水中的酚。通过扫描电镜(SEM)、能量弥散X射线能谱仪(EDS)及接触角测试仪对Si O_2/PDMS/PVDF复合膜材料进行了表征,并研究了Si O_2质量浓度、涂覆时间对Si O_2/PDMS/PVDF复合膜材料渗透蒸发性能的影响。当Si O_2填充质量浓度占PDMS质量浓度的12%,涂覆时间60 min条件下,制得的Si O_2/PDMS/PVDF复合膜具有最佳的渗透蒸发性能。保持进水温度50℃,膜后压力50 k Pa,进水流速10 L/h,酚通量达到7.16 g/(m~2·h),分离因子为4.26。     

疏水白炭黑填充PDMS-PA复合膜的渗透汽化性能

在聚二甲基硅氧烷(PDMS)层中引入疏水性气相法白炭黑,制成填充的硅橡胶-聚酰胺(PDMS-PA)多层复合膜;通过扫描电镜(SEM)观察了填充复合膜的截面形态,并考察了填充复合膜的渗透蒸发性能。结果发现,以PDMS层的质量为基准,填充少量的疏水性气相法白炭黑就能显著影响复合膜的渗透性能;填充复合膜的渗透通量随着白炭黑用量的增加而增加,而选择性则没有显著降低。在40℃、乙醇质量分数为5%的乙醇水溶液中,白炭黑质量分数为20%的PDMS-PA复合膜的渗透通量达到2 400 g/m2.h,比非填充复合膜的渗透通量高1倍多;而分离因子为7,稍低于非填充复合膜的8.5。此外,填充复合膜和非填充复合膜的分离性能对温度和浓度变化的依赖关系一致。     

基于ZIF-8的聚二甲基硅氧烷复合膜的研制

采用微波辅助合成法制备了沸石咪唑酯骨架材料-8(ZIF-8),再将ZIF-8与聚二甲基硅氧烷(PDMS)混合制得PDMS/ZIF-8复合膜,表征了ZIF-8晶体和复合膜的结构,并测试了复合膜的热稳定性、对水的接触角和对正丁醇的溶胀度.结果表明:成功制得了正六面体结构、平均粒径为4～6μm的ZIF-8晶体;PDMS/ZI...     

正交设计用于LDPE/LLDPE/β沸石复合膜的热封性能优化

采用正交设计方法研究了β沸石填充低密度聚乙烯(LDPE)/线型低密度聚乙烯(LLDPE)复合膜的热封性能,详细探讨了β沸石用量、热封温度、热封时间和热封压力等条件对复合膜热封强度的影响情况。结果显示,β沸石用量对β沸石填充LDPE/LLDPE复合膜热封强度的影响最大。β沸石的添加改变了复合膜的配方组成,对薄膜热封强度的影响程度明显超过了热封工艺条件的影响。在热封温度、热封时间和热封压力三因素中,热封时间对复合薄膜的热封性能影响非常显著,远高于热封温度和热封压力的影响程度;热封温度和热封压力对复合膜热封强度的影响不太显著。     

ZrO2 和Al2O3支撑的MFI 型沸石分子筛膜:支撑体材料对膜性能的影响

采用水热合成法，以纯SiO2为源物质，在介孔Y2O3掺杂的ZrO2(YZ)及大孔α-Al2O3支撑体上制备出高质量的MFI型沸石分子筛膜，通过H2／n-C4H10气体混合物的渗透分离和p-xylene的蒸发研究了不同支撑体上MFI型沸石分子筛膜分离性能，在较低温度范围，YZ支撑的MFI型沸石分子筛膜中n-C4H10的渗透率比Al2O3支撑的膜高很多，最大n-C4H10与H2的分离率达到500，Al2O3支撑的膜中py-xylene的蒸发流量随时间下降很快，而YZ支撑的膜中的蒸发流量则变化缓慢，用XRD对膜的晶体结构进行分析，通过多种温度下热处理不同支撑体上的膜样品研究了其热稳定性与支持体材料的关系，YZ支撑的MFI型沸石分子筛膜的MFI结构在1000摄氏度后仍能保持，而Al2O3支撑的膜950摄氏度时已完全转变为石英相，研究结果表明，YZ支撑的MFI型沸石分子筛膜比Al2O3支撑的膜表现出更好的厌不性，热稳定性以及抗阻塞性。     

TMCS修饰MFI分子筛膜的制备及乙醇/水分离稳定性的研究

采用三甲基氯硅烷（TMCS）作为修饰源对MFI分子筛膜进行表面改性,系统考察了TMCS浓度以及修饰时间对于MFI分子筛膜在分离乙醇/水混合物时的性能影响。SEM、XRD、²⁹Si NMR、FT-IR、接触角实验及分离实验结果表明,TMCS可以与硅羟基反应,嫁接分子筛膜表面,在消除膜表面硅缺陷的同时提高膜的疏水性及膜分离性能的稳定性。随着TMCS浓度以及反应时间的增加,修饰后MFI分子筛膜的通量及分离因子略有下降,但稳定性增强。在TMCS的浓度为0.4%（质量）,修饰时间为2 h时,所得到的膜具有最佳渗透汽化分离性能,并可在60℃下分离5%（质量）乙醇/水混合物时保持良好的稳定性。在连续90 h渗透汽化分离过程中,其渗透通量稳定在1.61 kg·m^-2·h^-1 左右,分离因子保持在20以上。     

Characterization and performance evaluations of sodium zeolite‐Y filled chitosan polymeric membrane: Effect of sodium zeolite‐Y concentration

Sodium zeolite‐Y (NaY zeolite) filled chitosan polymeric membranes were developed and characterized. The impact of adding different concentrations of NaY zeolite into the homogeneous chitosan membrane was investigated. The surface morphology, mechanical–physical properties, sorption, and pervaporation performance for the dehydration of isopropanol–water mixture separation by the pervaporation process were studied and evaluated. A homogeneous chitosan membrane showed preferential water sorption and permeation compared to isopropanol. The optimum concentration of NaY zeolite added to the homogeneous chitosan membrane was 0.4 wt %, which showed that the dispersion of the NaY zeolite was the most homogeneous and finely covered by the chitosan polymer in the zeolite–chitosan polymer interface. The tensile strength and percent strain at maximum of this membrane were 59.347 MPa and 27.5%, respectively. The sorption experiments showed that the degree of swelling was 6.54% with 1.01 wt % isopropanol sorbed in these membranes. The pervaporation separation tests demonstrated that the NaY zeolite filled chitosan membrane was capable for isopropanol–water mixture separation and improved the pervaporation separation index from 272 (homogeneous chitosan membrane) to 2687. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1740–1751, 2006     

Separation properties of alcohol–water mixture through silicalite-I-filled silicone rubber membranes by pervaporation

The structure and the adsorption–desorption properties of zeolite silicalite-I by different treatments after synthesis were studied. The pervaporation properties of the alcohol–water mixture through silicone rubber filled with zeolite silicalite-I by different treatments were also investigated. Treating silicalite-I by acid or/and under steam was found to eliminate the metallic impurities in the zeolite and to perfect the crystalline structure of the zeolite. After treatment, silicalite-I is more selective to alcohol and the desorption of the alcohol from the zeolite is also easier. The silicone rubber membrane filled with treated silicalite-I shows a high performance for alcohol extraction from the dilute aqueous solution by pervaporation. The separation factor of the poly(dimethyl siloxane) (PDMS) membrane filled with silicalite-I treated successively by acid and steam is about 30 when the ethanol content in the feed is 5 wt % at 50°C. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 629–636, 1998     

MFI型分子筛膜的制备及表征

采用无模板剂的二次生长合成方法,在-αA l2O3基膜上合成了MFI型分子筛膜,用XRD,SEM和气体渗透实验等方法进行表征,表明合成在-αA l2O3基膜的物质为MFI型分子筛。二次生长分子筛膜的正/异丁烷理想分离系数在298 K和473 K时分别为77和70,气体分离数据表明,2种分子筛膜对气体分离是由分子筛分占主导,同时分子筛膜完整无裂缺。不同温度,通过MFI分子筛膜渗透汽化分离质量分数分别为5%、50%和95%的乙醇/水的渗透通量和分离因子,结果表明渗透通量随温度的升高而升高,而分离因子随温度的升高却降低;渗透通量随乙醇质量分数的升高而降低,分离因子却随质量分数的升高而升高。     

Preparation of novel ZSM‐5 zeolite‐filled chitosan membranes for pervaporation separation of dimethyl carbonate/methanol mixtures

Novel mixed matrix membranes were prepared by incorporating ZSM‐5 zeolite into chitosan polymer for the pervaporative separation of dimethyl carbonate (DMC) from methanol. These membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD) to assess their morphology, intermolecular interactions, and crystallinity. Sorption studies indicated that the degree of swelling for zeolite‐filled membranes increased with zeolite content in the membrane increasing and the separation selectivity of DMC/methanol was dominated by solubility selectivity rather than diffusivity selectivity. The characteristics of these membranes for separating DMC/methanol mixtures were investigated by varying zeolite content, feed composition, and operating temperature. The pervaporation separation index (PSI) showed that 5 wt % of ZSM‐5 zeolite‐filled membrane gave the optimum performance in the PV process. From the temperature‐dependent permeation values, the Arrhenius activation parameters were estimated. The resulting lower activation energy values obtained for zeolite‐filled membranes contribute to the framework of the zeolite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Development of Novel NH4Y Zeolite‐Filled Chitosan Membranes for the Dehydration of Water‐Isopropanol Mixture Using Pervaporation

Abstract

NH₄Y zeolite‐filled chitosan membranes were developed for the separation of water‐isopropanol mixture using pervaporation process. The NH₄Y zeolite‐filled chitosan membranes were prepared using a solution technique with the variation of NH₄Y zeolite loading (0, 0.1, 0.2, 0.3, 0.4, 0.5 wt.%). The membranes morphologies were studied using Scanning Electron Microscopy (SEM) and the membranes mechanical strength were tested using the parameter of tensile strength and percent strain at maximum. The effects of NH₄Y zeolite loading on the liquid sorption characteristics and pervaporation performance were also evaluated. The diffusion coefficient of water and isopropanol for the chitosan membranes at different NH₄Y zeolite loading is estimated. The presence of NH₄Y zeolite in the chitosan membranes caused non‐homogeneous dispersion of NH₄Y zeolite crystals and membrane swelling due to its hydrophilic properties. However, the presence of NH₄Y zeolite was able to improve both tensile strength and percent strain at maximum of chitosan membranes. The presence of NH₄Y zeolite also increased the total permeation flux and separation factor simultaneously. The Pervaporation Separation Index shows that 0.2 wt.% of NH₄Y zeolite‐filled membrane gave the optimum performance in the pervaporation process. The diffusion coefficient estimated proves that the membranes were highly water selective.     

Preparation and characterization of HY zeolite‐filled chitosan membranes for pervaporation separation

A novel zeolite (HY)‐filled polymeric chitosan membrane was prepared. The membrane was characterized by wide‐angle X‐ray diffraction and a swelling test. The pervaporation (PV) experiments were also performed for an ethanol–water system. The results showed that the crystalline structure of chitosan was damaged with increase in the zeolite content, indicating a strong interaction between the HY zeolite and chitosan. The separation factor of the ethanol–water mixture by PV was improved by the filling zeolite. When the HY zeolite content in the membrane was 20 mass %, the separation factor reached the maximum and remained constant during the PV process. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1144–1149, 2001     

含氟体系中MFI型分子筛膜的制备及其乙醇/水分离性能

以氟化铵为矿化剂、四丙基溴化铵为模板剂,在负载晶种的钇稳定氧化锆(YSZ)中空纤维支撑体表面合成了MFI型分子筛膜,并用于乙醇/水的分离;系统考察了氟硅比(n_NH4F/n_SiO2)、合成时间等条件对膜分离性能的影响,在n_NH4F/n_SiO2为0.8、合成时间为8 h下合成出高性能膜,其通量达8.2 kg·m^-2·h^-1、乙醇/水分离因子为47;同时研究了MFI型分子筛膜在乙醇/水体系中的分离稳定性,揭示出该方法所合成膜表面无Si-OH,从而避免了Si-OH与乙醇反应而带来膜分离性能的下降.     

Zeolite filled P84 co-polyimide membranes for dehydration of isopropanol through pervaporation process

We have developed zeolite 5A and 13X embedded P84 co-polyimide membranes with enhanced permeability and selectivity for the pervaporation dehydration of isopropanol (IPA). It is found that a higher annealing temperature, i.e., is more favorable to improve adhesion between zeolite and polymer phase, and to enhance charge transfer complexes (CTCs) formation. FESEM, DSC and gas permeation results show that zeolite 13X has better compatibility with the matrix polymer than zeolite 5A because of stronger interactions between Na cations in zeolite 13X framework and electron acceptor groups of P84 polyimide. The addition of zeolite into the P84 dense membrane improves water sorption capacity and pervaporation separation performance significantly. Owing to the bigger pore size, larger pore volume, higher sorption capacity and better adhesion, the zeolite 13X incorporated P84 membranes has a much higher permeability than zeolite 5A filled membranes. Interestingly, both have comparably high selectivity possibly because of the effects of chain rigidification and partial pore blockage. The addition of zeolite 13X reduces activation energy for water permeation through the membrane but increases that for IPA permeation. However, the addition of zeolite 5A increases activation energy for both water and IPA permeation. Pervaporation permeability increases with zeolite 13X loading, while the selectivity achieves the maximum at 30 wt% zeolite 13X loading. When the zeolite 13X loading approaches 40 wt%, the adhesion between zeolite and polymer becomes poor and the membrane selectivity declines. A comparison between pervaporation and gas separation results reveals that pervaporation membranes can tolerate a higher degree of interstitial defects than gas separation membranes because of stronger molecular interactions between the feed and the polymer, and the larger molecular size difference between penetrants in the former.