紫精的负离子对耐水的紫精—聚合物膜的光致变色性能的影响

将含不同负离子的苄基紫精分散在混合有ＰＶＰ的ＭＭＡ－ＨＥＭＡ共聚物基质中可制成耐水的光致变色膜。它们的光致变色速度的大小随紫精负离子的不同而有如下序列：Ｖ６（ＰＦ６＾－）〉Ｖ５（ＢＦ４＾－）￣Ｖ４（ＣｌＯ４＾－）〉Ｖ３（ＣＨ３－苯环－ＳＯ３＾－）〉Ｖ２（Ｂｒ＾－）￣Ｖ１（Ｃｌ＾－）。这与这些紫精在ＤＭＦ中的溶解度以及在共聚物基质中的溶解性大小的序列相一致。负离子对这些光致变色膜在空气中的氧化退色速     

聚苯胺对2,5—二巯基—1,3,4—噻二唑氧化还原反应的电化学？…

研究了聚苯胺（ＰＡn）膜电极在２,５－二巯基－１,３,４－噻二唑（ＤＭcＴ）溶液中电化学处理或浸泡后的循环伏安（ＣＶ）曲线的变化规律。实验结果表明,ＰＡn膜电极在 ＤＭcＴ溶液中进行电化学处理或浸泡过程可使ＤＭcＴ进入ＰＡn膜内部与ＰＡn形成复合物。ＰＡn对ＤＭcＴ的电化学催化作用可能和二者之间形成的电子给体－受体复合物有关。该复合物的电何尝氧化还原特性不同于ＰＡn对ＤＭcＴ的电化学催化作用可能和得之间形成的     

氯化锂为添加剂制得的疏水聚偏氟乙烯不对称微孔膜的形态结构及其膜蒸馏性能

结合膜的形态结构研究了以 LiCl为添加剂制得的疏水 PVDF膜的膜蒸馏性能。与来用水溶液高分子添加剂制得的PVDF微孔膜相比,膜蒸馏性能有了较大提高,尤其具有更高的截留率。制得的微孔膜的蒸馏通量已接近商品膜的膜蒸馏通量,表明以LiCl为添加剂制得的PVDF疏水微孔膜是一种适用于膜蒸馏的较理想的疏水微孔膜。     

渗透汽化型酯化膜反应器研究聚合物／无机固体酸管式复合膜？…

设计了渗透汽化型管式膜反应器,以乙酸丁酯合成反应为探针,考察了Ｚｒ（ＩＶ）／ＰＶＡ,Ｚｒ（ＩＶ）－ＰＶＡ／ＰＶＡ两类聚合物担载无机固体酸管式复合膜的膜催化反尖性能。探讨了功能膜的组成,结构,反应条件等对膜反应和分离性能的影响以及同步膜分离过程对反应转化的促进作用。实验结果表明,膜催化酯化反应过程主要是依赖与料液接触侧膜表面层的催化活性,膜的催化活性是影响反应速率,特别是初期反应转化速率的主要因素,     

PVA／PEG共混渗透蒸发膜的盐水分离机理研究

以聚乙烯醇（ＰＶＡ）和聚乙二醇（ＰＥＧ）共混,甲醛交联制备亲水性高分子膜,用于渗适蒸发过程进行海水脱盐。ＰＥＧ的引入使盐－水分离成为可能, 到钠的引入使膜的分离通量明显提高。通过溶用蔗、ＰＥＧ水溶液的粘度和膜形态分析等方法对ＰＶＡ－ＰＥＧ体系的高分子网络结构和膜中相分离作了研究,发现了膜结构与渗透蒸发脱盐性能的基本关系。影响膜分离的因素除了化学亲合性之外,主要是膜的溶胀性和微相分离程度。ＰＥＧ的作     

渗透汽化型酯化膜反应器研究 聚合物/无机固体酸管式复合膜的膜反应性能

设计了渗透汽化型管式膜反应器,以乙酸丁酯合成反应为探针,考察了Ｚｒ（ＩＶ）／ＰＶＡ,Ｚｒ（ＩＶ）－ＰＶＡ／ＰＶＡ两类聚合物担载无机固体酸管式复合膜的膜催化反应性能。探讨了功能膜的组成,结构,反应条件等对膜反应和分离性能的影响以及同步膜分离过程对反应转化的促进作用。实验结果表明,膜催化酯化反应过程主要是依赖与料液接触侧膜表面层的催化活性,膜的催化活性是影响反应速率,特别是初期反应转化速率的主要因素,后期的超平衡转化则依赖于膜分离过程     

再生纤维素／聚乙烯醇共混膜的研究

由纤维素铜氨溶液与不同体积比（１－１０％）的聚乙烯醇（ＰＶＡ）水溶液共混制备了一系列再生纤维素共混膜．扫描电镜结果表明ＰＶＡ含量大于８％时，该共混膜产生明显相分离．当ＰＶＡ低于５％时，共混膜相容性较好．膜的结晶度，抗张强度，直角撕裂强度，断裂伸长及耐热性均优于单独用钢氨液制备的再生纤维素膜．此外，用流动速率法和超滤法测定了膜的孔径，渗透性及纯水通量，结果表明共混膜的孔性没有明显变化．本文得出：再生纤维素与５％ＰＶＡ共混能改善力学性能，并且能保持其生物降解性．     

TiO2纳米粒子膜的制备,表面态性质和光催化活性

在酸性和碱性条件下,用ＴｉＣｌ４水解法制备了ＴｉＯ２纳米粒子膜催化剂。采用原子力显微镜（ＡＦＭ）,Ｘ射线衍射（ＸＲＤ）,表面光电压谱（ＳＰＳ）和场诱导表面光电压谱（ＥＦＩＳＰＳ）测定了催化剂表面的微结构及能级结构。     

一种高灵敏固相测定新方法——聚氯乙烯膜光度法

对聚氯乙烯（ＰＶＣ）膜光度法的应用进行了全面综述,主要包括ＰＶＣ膜光度法的特点、ＰＶＣ膜的制作、显色机理和应用以及发展前景。     

亚相pH对气水界面上VE/DPPC单分子膜的影响

通过表面压－分子面积等温线的测定，考察了亚相ｐＨ对气水界面上的维生素Ｅ（ＶＥ）／二棕榈酰基磷脂酰胆碱单分子膜的影响。亚相ｐＨ降低不改变ＤＰＰＣ单分子膜的崩裂压，但使ＶＥ单分子膜的崩裂压明显增大，不改变ＶＥ单分子膜的平均分子面积，但使ＤＰＰＣ单分子膜凝缩，低表面压下，ＶＥ对ＤＰＰＣ单分子膜的膨胀作用在纯水上很小，在ｐＨ为１的亚相上则很明显，这提示在低ｐＨ的亚相上，ＶＥ／ＤＰＰＣ单分子膜中的极性头基间     

THE INFLUENCE OF PEG MOLECULAR WEIGHT ON MORPHOLOGIES AND PROPERTIES OF PVDF ASYMMETRIC MEMBRANES

The preparation and properties of asymmetric poly(vinyldiene fluoride)(PVDF)membranes are described in this study.Membranes were prepared from a casting solution of PVDF,N,N-dimethylacetamide(DMAc)solvent and water- soluble poly(ethylene glycol)(PEG)additives by immersing them in water as coagulant medium.Experiments showed that when PEG molecular weight increased,the changes in the resultant membranes' morphologies and properties showed a transition point at PEG6000.This indicated that PEG with a relati...     

Novel cellulose acetate membrane blended with phospholipid polymer for hemocompatible filtration system

To improve the blood compatibility of cellulose acetate (CA) membranes for hemofiltration, a novel CA membrane blended with 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer was designed for a hemocompatible filtration system. The MPC copolymer (PMB30) was synthesized from MPC and n-butyl methacrylate. The polymer solution for making the membrane was prepared from a solvent mixture composed of N,N-dimethylformamide, acetone, and 2-propanol. The CA and CA/PMB30 blended membranes with an asymmetric and porous structure were prepared by a phase inversion process. The mechanical properties and solute permeability of the CA/PMB30 blended membrane could be controlled by preparation conditions such as the composition of the solvents and the solvent evaporation time. The CA/PMB30 blended membrane showed both good water and solute permeabilities in comparison with the CA membrane. Also, the molecular weight of the solute passed through the membrane was changed by the addition of PMB30, and good permselectivity could be obtained. Moreover, the CA/PMB30 blended membranes had excellent blood compatibility such as protein adsorption resistivity compared to the CA membrane due to location of the MPC units in the PMB30 at the surface.     

Experimental and theoretical study on propylene absorption by using PVDF hollow fiber membrane contactors with various membrane structures

Five kinds of asymmetric poly(vinylidene fluoride) (PVDF) hollow fiber membranes with considerable different porosities at the inner and outer surfaces of the membrane were prepared via thermally induced phase separation (TIPS) method and applied for propylene absorption as gas–liquid membrane contactors. A commercial microporous poly(tetrafluoroethylene) (PTFE) hollow fiber membrane was also used as a highly hydrophobic membrane. Experiments on the absorption of pure propylene into silver nitrate solutions were performed and the effects of membrane structure, inner diameter, silver nitrate concentration and absorbent liquid flow rate were investigated at 298 K. PVDF membranes prepared by using nitrogen as bore fluid had lower inner surface porosity than the membranes prepared with solvent as bore fluid. Except the membrane with a skin layer at the outer surface, propylene absorption flux was inversely proportional to the inner diameter of the hollow fiber membrane, and propylene absorption rate per fiber was almost the same. Propylene flux increased with increasing the silver nitrate concentration and also with increasing the absorbent flow rate.A mathematical model for pure propylene absorption in a membrane contactor, which assumes that the membrane resistance is negligibly small and the total membrane area is effective for gas absorption, was proposed to simulate propylene absorption rates. Experimental results were satisfactorily simulated by the model except for the membrane having a skin layer. The model also suggested that propylene is absorbed in silver nitrate solutions accompanied by the instantaneous reversible reaction. This paper may be the first experimental and theoretical study on propylene absorption in membrane contactors.     

Preparation of NOx modified PMMA-EGDM composite membrane for the recovery of chromium (VI)

A non-interpenetrating cross-linked poly (methyl methacrylate-ethylene glycol dimethacrylate) copolymer ultrafiltration membrane on a microporous ceramic support has been prepared from the monomers in two stages. The polymer membranes thus obtained have been nitrated using NO_x (a mixture of NO and NO₂) by the gas phase reaction at 80 °C. Separation experiments on the chromium (VI) salt solution have been carried out using unmodified (giving 68% rejection per pass) and nitrated membranes (giving as much as 67% rejection per pass). For nitrated membranes, the water flux and the solute flux increased with time of nitration about hundred folds because of the increase in the hydrophilicity as well as the pore size.     

熔纺聚氨酯系中空纤维膜的结构与性能

将聚氨酯/聚偏氟乙烯/聚乙二醇(PU/PVDF/PEG)熔融共混纺丝制得中空纤维膜,对纤维膜的微孔结构与性能进行研究,分析影响其水通量衰减的因素。结果表明:所得纤维膜具有界面及非界面微孔结构;随着水通量工作环境的变化,膜孔结构发生相应变化,表现出压力及温度响应性能;而经热处理后,所得膜部分微孔闭合,水通量下降;随测试时间延长,膜结构趋于致密化,水通量衰减。     

Reverse osmosis filtration for space mission wastewater: membrane properties and operating conditions

Reverse osmosis (RO) is a compact process that has potential for the removal of ionic and organic pollutants for recycling space mission wastewater. Seven candidate RO membranes were compared using a batch stirred cell to determine the membrane flux and the solute rejection for synthetic space mission wastewaters. Even though the urea molecule is larger than ions such as Na+, Cl-, and NH4+, the rejection of urea is lower. This indicates that the chemical interaction between solutes and the membrane is more important than the size exclusion effect. Low pressure reverse osmosis (LPRO) membranes appear to be most desirable because of their high permeate flux and rejection. Solute rejection is dependent on the shear rate, indicating the importance of concentration polarization. A simple transport model based on the solution-diffusion model incorporating concentration polarization is used to interpret the experimental results and predict rejection over a range of operating conditions. Grant numbers: NAG 9-1053.     

Study on hypochlorite degradation of aromatic polyamide reverse osmosis membrane

A serious limitation of most commercial polyamide reverse osmosis (RO) membranes is their sensitivity to chlorine attack. By studying the hypochlorite degradation of aromatic polyamide RO membrane, this work was to get some understandings in the prevention of membrane depreciation and develop membranes with improved chlorine resistance. Membrane performances, including water flux and salt rejection, were evaluated before and after hypochlorite exposure under different pH and concentration conditions. The results showed that chlorination destroyed hydrogen bonds in polyamide chains, causing a notable decline of membrane flux especially in acid environment; however, membrane performance was slightly improved after the treatment of alkaline hypochlorite solution for a certain time, which was probably due to the effect of amine groups in barrier layer. Based on the attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) characterizations and performance measurements, the results indicated that N-chlorination reaction of aromatic polyamide was also reversible, in other words, the N-chlorinated intermediate could be regenerated to initial amide with the alkaline treatment before ring-chlorination reaction. This conclusion provided several relative suggestions for membrane cleaning procedures. Finally, a method adopting surface coating was proposed to develop membranes with good chlorine resistance, and the preliminary results showed its potential for applications.     

Modelling of the pore size distribution of ultrafiltration membranes

A dilute aqueous solution of polydisperse neutral dextrans was used to determine the sieving properties (flux and rejection) of porous polyacrylonitrile membranes. Gel ermeation chromatography was used to measure the solute mole and concentration in the permeate. From these data, rejection coefficients were calculated as a function of solute molecular size. A mathematical model was then developed to relate the flux and solute rejection to pore size distribution and the total number of pores, based upon the assumption that solute rejection was the result of purely geometric considerations. As a first approximation, a solute molecule was considered either too large to enter a membrane pore, or if it entered, its concentration in the permeate from that pore, as well as the solvent flux through the pore, were not affected. This model also considered the effects of steric hindrance and hydrodynamic lag on the convection of solute through a membrane. The shape and sharpness of pore size distributions were found to be useful in comparisons of ultrafiltration membranes.     

Fabrication and Performance of a Low Operating Pressure Nanofiltration Poly（vinyl chloride） Hollow Fiber Membrane

A low operating pressure nanofiltration membrane is prepared by interfacial polymerization between m-phenylenediamine(MPDA) and trimesoyl chloride(TMC) using PVC hollow fiber membrane as supporting.A series of PVC nanofiltration membranes with different molecular weight cutoff(MWCO) can be obtained by controlling preparation conditions.Chemical and morphological characterization of the membrane surface was carried out by FTIR-ATR and SEM.MWCO was characterized by filtration experiments.The preparation conditions were investigated in detail.At the optimized conditions(40 min air-dried time,aqueous phase containing 0.5% MPDA,0.05% SDS and 0.6% acid absorbent,oil phase containing 0.3% TMC,and 1 min reaction time),under 0.3 MPa,water flux of the gained nanofiltration membrane reaches 17.8 L/m2·h,and the rejection rates of methyl orange and MgSO4 are more than 90% and 60%,respectively.     

Fouling of reverse osmosis membranes by biopolymers in wastewater secondary effluent: Role of membrane surface properties and initial permeate flux

Reverse osmosis (RO) is being increasingly used in treatment of domestic wastewater secondary effluent for potable and non-potable reuse. Among other solutes, dissolved biopolymers, i.e., proteins and polysaccharides, can lead to severe fouling of RO membranes. In this study, the roles of RO membrane surface properties in membrane fouling by two model biopolymers, bovine serum albumin (BSA) and sodium alginate, were investigated. Three commercial RO membranes with different surface properties were tested in a laboratory-scale cross-flow RO system. Membrane surface properties considered include surface roughness, zeta potential, and hydrophobicity. Experimental results revealed that membrane surface roughness had the greatest effect on fouling by the biopolymers tested. Accordingly, modified membranes with smoother surfaces showed significantly lower fouling rates. When Ca²⁺ was present, alginate fouled RO membranes much faster than BSA. Considerable synergistic effect was observed when both BSA and alginate were present. The larger foulant particle sizes measured in the co-existence of BSA and alginate indicate formation of BSA-alginate aggregates, which resulted in greater fouling rates. Faster initial flux decline was observed at higher initial permeate flux even when the flux was measured against accumulative permeate volume, indicating a negative impact of higher operating pressure.