催化与PV双功能中空纤维复合膜制备及其应用过程

以聚丙烯腈(PAN)中空纤维膜为支撑底膜,聚乙烯醇(PVA)为渗透汽化(PV)层,全氟磺酸树脂(PFSA)-聚乙烯醇(PVA) -纳米材料(SiO2、Al2O3和TiO2)为催化层,制备了具有催化和PV双功能的PFSA- PVA- SiO2 (Al2O3和TiO2 )/PVA/ PAN中空纤维复合膜.以乙酸-乙醇酯化反...     

陶瓷中空纤维担载有机共混渗透汽化脱水膜的制备及表征

在多孔陶瓷中空纤维支撑体表面用浸渍提拉法制备了致密、无缺陷的有机分离层,其中有机分离层是以马来酸酐交联的对水具有分离选择性的壳聚糖(CS)-聚乙烯醇(PVA)共混复合材料.采用扫描电子显微镜、溶胀度分析与渗透汽化性能测试等手段,系统地考察了支撑体孔径和不同CS和PVA共混比例对膜性能的影响.同时研究了进料液水含量和操作温度对乙酸乙酯脱水渗透汽化性能的影响.实验结果表明,该复合膜在乙酸乙酯渗透汽化脱水过程中表现出优异的分离性能,在操作温度50℃,料液水质量分数为3％时,CS共混比(质量分数)为60％的PVA-CS共混复合膜的渗透通量高达1 195 g/(m2·h),对水的分离因子大于10 000.所制备的陶瓷中空纤维担载有机共混渗透汽化脱水膜将具备良好的商业应用前景.     

动态LBL组装聚离子膜对乙醇/水体系的渗透汽化性能

采用动态层-层吸附成膜法(动态LBL),以聚醚砜超滤膜为基膜,以聚丙烯酸(PAA)、聚乙烯亚胺(PEI)为聚离子制备了聚离子复合膜.考察了动态成膜与静态吸附成膜的膜性能比较,研究了动态过滤时间、聚离子浓度、进料浓度、温度等因素对该复合膜渗透汽化性能的影响;并对复合膜表面和截面做了扫描电镜分析.在40℃时,该复合膜对乙醇/水体系的分离因子可达1300,渗透通量约150 g/(m2.h),体现了较好的渗透汽化分离性能.     

UIO-66-NH_2渗透汽化复合膜制备及乙醇脱水

金属有机骨架材料(MOFs)改性高分子渗透汽化复合膜是目前的研究热点.本文采用水热合成法制备UIO-66-NH_2,利用旋涂法在改性的聚丙烯腈(PAN)底膜表面涂覆海藻酸钠(SA)、聚乙烯醇(PVA)和UIO-66-NH_2混合液制备活性分离层,采用顺丁烯二酸交联分离层制备SA-PVA-MOF/PAN渗透汽化复合膜.考察了SA、PVA和UIO-66-NH_2浓度对复合膜形貌结构、亲水性能和醇水分离效果的影响.研究结果表明,复合膜分离层含质量分数1%SA、4%PVA和0.8%UIO-66-NH_2时,75℃条件下复合膜对质量分数85%乙醇水溶液的渗透通量最高可达905 g/(m~2·h),此时分离因子为308.     

高选择性PDMSP/VDF复合膜渗透汽化分离乙醇/水混合物

以聚偏氟乙烯( PVDF)为基膜、聚二甲基硅氧烷(PDMS)为选择层制备了PDMS/PVDF复合膜,应用于渗透汽化分离乙醇/水混合物.系统研究了膜交联温度、操作温度、物料浓度和膜下侧压力对乙醇/水混合物的渗透汽化分离性能的影响,发现经130℃交联的复合膜在温度为60℃时,对乙醇的分离因子为8.23,可将乙醇浓度从体积分...     

TiO2-VOx纳米复合膜制备及耐腐蚀性研究

采用溶胶-凝胶法和浸渍提拉技术在316L不锈钢(316Lss)表面构筑纳米TiO2,TiO2/TiO2-VOx/TiO2复合膜,应用AFM和XRD表征膜的形貌及结构,并用光、电化学方法测试复合膜在0.5 mol/L NaCl溶液中暗态或紫外照射下的耐腐蚀性能,结果表明TiO2/TiO2-VOx/TiO2复合膜具有双重保护功能,即在紫外光照下可以起到光生阴极保护的作用,特别是当停止光照后,光生电位仍可维持在较低的电位长达6h以上;作为覆盖层纳米复合膜又可作为良好的阻挡层显著提高金属的耐腐蚀性.     

乙基纤维素/TiO2复合膜的制备及气体渗透性能

以乙基纤维素(EC)和正钛酸丁酯(TBT)为主要原料,通过溶胶-凝胶(Sol-Gel)法制备了EC/TiO2复合膜。研究了TiO2粒子在复合膜中分布形貌、复合膜的结构变化及对气体渗透和分离性能的影响。结果表明,TiO2质量分数达到25%时,微米级的TiO2粒子均匀分散在复合膜中,复合膜形成有机-无机三维网络结构,测试气体在膜中的渗透行为主要受动力学因素控制,其中H2、O2透气系数分别增大至纯EC膜的1.8倍和1.3倍,H2/N2及O2/N2分离性能略有提高。     

高交联温度下聚二甲基硅氧烷/聚醚砜渗透汽化复合膜的制备及性能研究

以聚醚砜(PES)平板多孔膜为支撑层,聚二甲基硅氧烷(PDMS)膜为分离层,在高温交联条件下制备了PDMS/PES渗透汽化复合膜。用扫描电镜对复合膜形貌进行了表征,复合膜表面平整、致密,分离层与支撑层外表面结合紧密。研究了PDMS质量分数对膜产生最高衍射峰时对应的2θ值、水与乙醇的接触角以及以10%(质量分数)乙醇水溶液为料液,30℃下复合膜渗透汽化分离性能的影响。结果表明:随着PDMS含量的增加,产生最高衍射峰时对应的2θ值先增大后减小。当PDMS含量为15%(wt,质量分数,下同)时,PDMS/PES复合膜有良好的疏水性和亲醇性,PDMS/PES复合膜的分离因子最大,最大值为4.60,对应的渗透通量为10325.54g/(m~2·h),分离指数出现最大值为47483.02。因此,15%PDMS条件下制备的PDMS/PES复合膜综合性能最好。     

渗透汽化复合膜的支撑层对分离性能的影响

研究了多种聚合物膜作为复合膜的多孔支撑层时的性能及其复合膜分离乙醇水给 物时的渗透汽化性能。结果表明,ＣＡ、ＰＡＮ－ＳＳ和ＰＳＡ分别为多孔支撑层的膜材料时,ＰＶＡ复俣的渗透汽化性能优良,尤其是ＰＶＡ／ＣＡ复合膜表现出特别优异的渗秀汽化分离性能。用国产涤纶布增强、聚合物浓度较高的铸膜液制备成厚度适宜的膜为支撑层,可获得理想分离性能的渗透汽化复合物。     

TCY交联ACM渗透汽化膜对水中乙酸乙酯的分离

以三聚硫氰酸(TCY)为交联剂对丙烯酸酯橡胶(ACM)进行交联制得ACM/聚四氟乙烯(PTFE)渗透汽化复合膜。用红外光谱(FT-IR)研究了交联反应机理,用扫描电镜(SEM)表征ACM/PTFE复合膜微观结构。考察了交联剂用量、交联温度、料液浓度和料液温度对复合膜渗透汽化法分离乙酸乙酯/水性能的影响。FT-IR表明,TCY的-HS基和ACM的-CH2Cl基之间发生了脱HCl反应。当m(TCY)∶m(ACM)为5∶100,在150℃交联2h所制的复合膜在50℃时,对7%的乙酸乙酯/水溶液渗透通量为3631 g/(m2.h),分离因子为239。升高温度至70℃时,渗透通量可达7918g/(m2.h),分离因子降低到195。     

支撑层对PDMS复合膜渗透汽化性能的影响

以相转化法制备的聚偏氟乙烯(PVDF)、聚丙烯腈(PAN)、聚砜(PSF)三种多孔膜作为支撑层,制备聚二甲基硅氧烷(PDMS)复合膜用于渗透汽化乙醇/水混合物的分离。采用能量色散X射线光谱仪(EDX)定量表征了PDMS在支撑层表面的厚度(L0)和支撑层内的渗入深度(Li),研究发现,PDMS在各支撑层表面的厚度、支撑层内渗入的厚度有显著差异,PDMS复合膜的渗透通量与(L0+Li)间存在近似的线性关系,表明PDMS在支撑层中渗入深度不同是造成不同底膜支撑的PDMS复合膜渗透汽化性能差异的根本原因。文中提出选择层总厚度(Lt=L0+Li)概念,通过线性拟合得到PDMS复合膜渗透通量与Lt之间的定量关系,可以用来估算PDMS复合膜的渗透通量,并预测复合膜渗透通量极大值。     

Fabrication of a graphene oxide/nanoscale aramid fiber composite membrane with improved hydrophilicity and mechanical strength via a fast-drying method using absolute ethanol as proton donor

The synergic effect between each component in composite membrane has created a new concept to fabricate membrane materials and widen their applications. Previous trials have suggested that micrometer-scale aramid fiber (MAF) could be effectively split into nanoscale aramid fiber (NAF) by dissolution in DMSO/KOH. Addressed herein is a time-saving approach to incorporate graphene oxide (GO) together with NAF to fabricate composite membranes through π–π stacking interactions. NAF–GO composite membranes (GO/NAF) containing gradient contents of GO have been prepared using absolute ethanol as proton donor, making the drying process facile and fast. The obtained composite membranes exhibit excellent hydrophilicity and enhanced mechanical performance. The chemical structure, morphology, crystallization and mechanical strength of GO/NAF composite membranes are characterized, respectively, and the hydrophilicity of GO/NAF is also evaluated by static water contact angle measurements. In the case of medium GO content (1 wt%) used in this study, the composite membrane possesses both optimal mechanical performance and better hydrophilicity compared to other supplementations, indicating that absolute ethanol is a promising proton donor for flocculation, which makes the post-treatment process more economic.     

聚乙烯醇/聚乙烯吡咯烷酮共混膜的制备和性能

制备了聚乙烯醇(PVA)、PVA/聚乙烯吡咯烷酮(PVP)与戊二醛交联的PVA/PVP膜用于渗透蒸发对乙酸乙酯/乙醇/水三元共沸体系脱水。采用傅立叶变换红外光谱(FT-IR),X射线散射(XRD)和扫描电镜(SEM)等对膜的物理化学结构及形貌进行了表征。考察了PVP含量、交联度对共混膜结构和亲水性的影响。考察了PVP含量、交联度和温度对PVA均质膜的分离性能和溶胀行为的影响。结果表明,交联的PVA/PVP共混膜对乙酸乙酯/乙醇/水有着优异的分离性能。     

Removal of water from aroma aqueous mixtures using pervaporation processes

In the field of food technology the main applications of pervaporation through hydrophilic membranes are the removal or extraction of water from aroma azeotropic aqueous mixtures. In this study, experiments for removal of water containing aroma compounds of ethanol, propanol, butanol, hexanol, ethyl acetate and acetic acid were performed through a composite, plate and frame type hydrophilic PVA (poly vinyl alcohol) membrane in a 0.5 m² plane module at constant feed temperature and permeate Vacuum pressure. The analysis is presented in terms of variations in permeation flux and separation factor. The results show the decrease in separation factor as well as permeation flux with the increase of alcohol in feed. Hexanol does not permeate through PVA membrane. Activity coefficient of water is higher than that of organic. Pervaporation selectivity differ from Liquid-vapor thermodynamic equilibrium.     

高通量ZSM-5填充硅橡胶复合膜渗透汽化性能研究

以硅铝比为360的ZSM-5型沸石对聚二甲基硅氧烷(PDMS)进行填充,以聚偏氟乙烯(PVSF)为支撑层,制备了ZSM-5填充PDMS/PVDF复合膜,用于渗透汽化乙醇/水混合物的分离.研究了沸石填充量、操作温度、进料液浓度对乙醇/水的渗透汽化分离性能的影响,发现该复合膜较文献报道中的沸石填充膜,其渗透通量有了明显的提高,在50℃沸石填充量为40%时,对乙醇的分离因子为11.7,其渗透通量达到749.8 g/(m2·h).随着操作温度的升高或料液中乙醇浓度升高,渗透通量增大,分离因子下降.     

Plasma-treated polyethersulfone coated with crosslinked poly(vinyl alcohol): composite membranes for pervaporation dehydration of ethanol

Composite membranes with crosslinked poly(vinyl alcohol) matrix as selective layer coated on a polyethersulfone supporting porous layer were prepared aiming at separating ethanol/water mixtures by pervaporation. A polyethersulfone asymmetric microporous membrane was synthesized by the wet phase inversion process. The support membrane was then exposed to air plasma to activate the surface. The selective dense layer was obtained by coating of PVA and a crosslinking agent over the polyethersulfone substrate, followed by thermal treatment. The morphology was examined by scanning electron microscopy (SEM) for both, support membrane and the coated polymeric layers. Surface physicochemical properties were evaluated through measuring the contact angle (θ) and the estimation of surface free energy (γ_S) and adhesion work. The surface chemical composition of support membrane and coated hydrophilic layers were characterized by infrared spectra with horizontal attenuated total reflectance (FT-IR/HATR). The swelling degree of PVA dense membranes, and the pervaporation performance of the crosslinked PVA/PES composite membranes, manufactured with several coating steps, were evaluated with water/ethanol (20/80 wt%) mixtures at temperatures in the range of 30–60 C. Results of the effective pervaporation dehydration of ethanol are discussed in terms of membrane morphology and the solution-diffusion transport mechanism.     

PVA/PAN渗透汽化膜分离乙酸乙酯—乙醇—水体系的研究

采用相转化法制备了平板PAN超滤膜,并采用涂覆法制备了酒石酸交联的PVA/PAN复合膜.利用红外谱图和扫描电镜对复合膜表面化学组成及膜结构进行了分析和表征.同时,以乙酸乙酯-乙醇-水体系为研究对象,分别研究了交联荆的含量以及料液温度等对复合膜性能的影响.结果表明在同一温度下,交联剂含量增加,膜的溶胀度减小,渗透通量减小.选择性增高.随温度的升高,渗透通量增大,而选择性降低.在30～50℃的料液温度下,复合膜的总通量为30～150 g/(m2·h),分离因子可达480～29 000.     

One-step dynamic assembly of polyelectrolyte complex membranes

During the past decades, layer-by-layer (LbL) assembly technique based on electrostatic adsorption of oppositely charged polyelectrolytes (PEs) has been one of the most frequently utilized processes for assembling ultra-thin film. However, LbL process is also recognized as a time-consuming process, especially for assembly of dense membranes. In this paper, a one-step dynamic assembly based on electrostatic adsorption was developed to prepare the PE complex membranes. The chitosan (CS), used as a model polycation, was dynamically deposited on a hydrolyzed polyacrylonitrile (PAN) support membrane with negative charges under a selected pressure to form a PE complex membrane for pervaporation separation of water–ethanol mixture. Compared with traditional dip-coating method, this new assembly process could offer some advantages such as the formation of selective layer with dilute solution, easily used for different membrane module types and suitable for large scale applications. The assembly conditions such as dynamic pressure, CS molecular weight, and CS concentration were investigated. The appropriate conditions for assembly were: dynamic pressure, 0.2 MPa; CS molecular weight, 82,000; and CS concentration, 0.5 wt.%. In the case of pervaporation of 95 wt.% ethanol/water mixtures, the separation factor and the permeate flux of the CS polyelectrolyte complex membranes were 422 and 230 g/(m² h) (60 °C), respectively. The cross-linking treatment with glutaraldehyde and sulfuric acid were subsequently performed. It was found that the separation performance was improved by the cross-linking treatment. Finally, inner skin hollow fiber PE complex membranes were also successfully explored using one-step dynamic assembly for pervaporation dehydration. The proposed process will offer a new approach to obtain a relatively integrated PE complex membrane.     

渗透汽化膜分离酯化反应的研究

以乙酸和正丁醇的酯化的为探针反应，以多元酸交联的ＰＶＡ／ＰＳＡ复合膜为分离膜，对渗透汽化膜分离酯化反应进行了研究，考察了该复合膜的分离性能及其对酯化反应转化率的影响，结果表明，本文研制的复合膜能选择性将反应中生成的水连续除水，从而使反应转化率显著率提高，另外，用ＳＥＭ的方法对研制的复合膜的结构进行了观察。