Synthesis and study of RO performance of aromatic polyamide hydrazide membranes

Aromatic polyamide hydrazide polymeric membranes were synthesized by dissolving freshly prepared polymer in dimethyl acetamide using lithium salt as additive. The effect of various casting parameters like polymer to solvent ratio, additive to polymer ratio, time and temperature of solvent evaporation, etc., on the RO membrane performance was studied. The membrane performance under various operational parameters like applied pressure, feed molarity and temperature are presented. The membranes prepared from the polymer samples were characterised in terms of pure water permeability constant (A) and solute transport parameter (D_AM/Kδ).     

SOLUTE DIFFUSION IN SWOLLEN MEMBRANES III. NON-EQUILIBRIUM THERMODYNAMIC ASPECTS OF SOLUTE DIFFUSION IN POLYMER NETWORK MEMBRANES

The Kedem-Katchalsky phenomenological coefficients L_p, L_D and L_pD of albumin transport through PVA membranes were calculated through knowledge of the corresponding multicomponent diffusion coefficients. Non-equilibrium thermodynamic considerations for non-ideal systems of hydrophilic solutes in water were used to describe the transport of albumin through swollen non-porous (gel) polymeric membranes. Experimental results and the effect of polymer structure are also discussed.     

A review on Zeolite-Reinforced Polymeric Membranes: Salient Features and Applications

Various types of synthetic polymeric membranes have been fabricated for separation purposes in industry/laboratory. Zeolite is ceramic-based material and well known for its antiwear resistance and high mechanical strength. Mixed matrix membranes are the latest membrane technology constituting inorganic nanoparticle phase and organic polymer phase. The review represents various types and applications of zeolite-reinforced polymeric membranes. Consequently, fabrication procedure and working principle of zeolite-reinforced mixed matrix (polyimide, polysulfone, polycarbonate) membranes have been discussed. The significant relevance of polymer/zeolite membranes is in water purification, medical, catalytic, and gas separation industries. Improvement in polymeric membrane properties has been observed through incorporation of zeolite filler.     

Synthesis,Characterization, and Visible Light Degradation of Rhodamine B Dye by Carbon-Covered Alumina Supported Pd-TiO2/Polysulfone Membranes

Palladium doped titania nanoparticles supported on carbon-covered alumina (CCA/Pd-TiO₂) impregnated polysulfone (PS) membranes were prepared by the phase inversion technique. The nano-sized CCA/Pd-TiO₂ nanoparticles were uniformly dispersed in 18 wt% PS casting solution to synthesize CCA/Pd-TiO₂ polysulfone membranes (PS/CCA/Pd-TiO₂). The amount of the CCA/Pd-TiO₂ was varied between 0.25% and 0.5% to form two types of membranes. These were casted on a non-woven fabric. The nanoparticles were added in order to enhance the photodegradation potential of the PS membranes under visible light. Raman, XRD, SEM, TGA, TGA-FTIR was used to characterize the membranes. The mechanical strength of the membranes was determined with an Instron tensile tester. The SEM results suggested that these membranes had a high degree of porosity and the nanoparticles were distributed on and within the PS membrane. The Raman analysis revealed the presence of the nanoparticles within the membrane matrix while the XRD results exposed the probability of interactions between the polymer and the nanoparticles. The two membranes were then tested for their capability to photodegrade Rhodamine B under visible light illumination. The 0.5% PS/CCA/Pd-TiO₂ membrane photodegraded 80.4% of the dye while the 0.25% PS/CCA/Pd-TiO₂ membrane degraded 70.8% of Rhodamine B over a 270 min period. The photodegradation followed a pseudo first-order reaction rate and the apparent rates were 0.00597 and 0.00448 min^?1 for 0.5% PS/CCA/Pd-TiO₂ membrane and 0.25% PS/CCA/Pd-TiO₂, respectively.     

用于甲醇燃料电池的聚砜阳离子交换膜的构⁃效关系

基于酰基化反应制备了氯丁基化聚砜（BPS）和氯戊酰基化聚砜（VPS）,再以8?羟基?1,3,6?芘三磺酸三钠（TS）为试剂经过亲核取代反应制备了侧链长度不同的芘磺酸型聚砜4PS?SA和5PS?SA,并采用注膜法制备了4PS?SA和5PS?SA系列阳离子交换膜;通过红外光谱仪（FTIR）、紫外?可见分光光度计、核磁共振仪（¹H?NMR）和原子力显微镜（AFM）测试和表征了其结构和磺酸基团含量,并探究了柔性侧链对其性能的影响。研究表明,4PS?SA和5PS?SA阳离子交换膜表现出良好的尺寸稳定性和阻醇性能;随着温度的升高,膜的吸水率、吸水溶胀率和质子传导率增加;在相同离子交换容量（IEC）下,具有较长侧链的5PS?SA尺寸稳定性和质子传导率更好,其中5PS?SA?3在室温和85 ℃下的溶胀率仅为23.7 %和39.1 %,质子传导率为0.093 S/cm和0.142 S/cm,甲醇扩散系数仅为7.09×10^-7 cm²/s,表现出很好的综合性能,有望用于阳离子交换膜燃料电池的实际生产应用。     

Studies on cellulose acetate‐carboxylated polysulfone blend ultrafiltration membranes. III

Enhancement of the hydrophilicity in polymeric membrane materials results in membranes with higher flux and better membrane characteristics. Hence, polysulfone was carboxylated and ultrafiltration membranes were prepared from blends of cellulose acetate and carboxylated polysulfones having various degrees of carboxylation with a total polymer concentration of 20 wt % in casting solution and at different blend polymer compositions. The effects of degree of carboxylation on membrane characteristics such as compaction, pure water flux, and membrane hydraulic resistance (R_m) have been investigated. The influence of the polymer concentration in the blend solution on the performance of blend membranes at various blend polymer compositions has also been investigated and compared with that of blend membranes prepared from blends of cellulose acetate and polysulfone or carboxylated polysulfone with a total polymer concentration of 17.5 wt %. Further, the solute rejection performance of the membranes has also been investigated by subjecting the membranes to metal ion permeation studies using polyelectrolyte‐enhanced ultrafiltration. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 976–988, 2005     

Performance of a newly developed hydrophilic additive blended with different ultrafiltration base polymers

The capability of modifying ultrafiltration (UF) membranes with different base‐polymers using a newly synthesized hydrophilic additive was investigated in this study. Five typical base‐polymers were tested: cellulose acetate (CA), polyetherimide (PEI), polyethersulfone (PES), polysulfone (PS), and polyvinylidene fluoride (PVDF). The changes in characteristics and performance of the membranes were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle analysis, and solute transport tests. It was found that the effect of the hydrophilic additive was different for each polymer. Higher additive contents resulted in higher permeation flux. A visible effect on water content and permeability was obtained but the impact was not shown clearly in contact angles, possibly the additive's concentration was not sufficiently high at the surface. In term of flux enhancement the PES and PVDF membranes benefited the most by the addition of the hydrophilic additive. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Metal Removal Studies by Composite Membrane of Polysulfone and Functionalized Single-Walled Carbon Nanotubes

Composite nanofiltration membranes were prepared by incorporating single-walled carbon nanotubes (SWNTs) into polysulfone polymer via the phase inversion method. Addition of SWCNTs resulted in the reduction of the pore size due to nanosize (0.7-1.3 nm) diameter of SWCNTs used. The increase in carbon nanotubes makes the surface of the membranes smoother, although the solvent and nonsolvent exchange process becomes slower due to increase in viscosity of the blend solution. The addition of SWCNTs improved the rejection of metal ions, the oxidized functionalized C/PS composite membranes gave 96.8% removal for Cr(VI), 87.6% for As(III), and 94.2% removal for Pb(II) which was just 30.3%, 28.5%, and 28.3%, respectively, with unblended virgin polysulfone membrane.     

PVC/D2EHPA聚合物包容膜对水相中苯酚的分离

以二-(2-乙基己基) 膦酸(D2EHPA,P204)为载体,制备了聚氯乙烯(PVC)为膜基材的系列聚合物包容膜(PD-PIM),用FTIR、XRD及AFM表征了PD-PIM的化学组成、结晶行为和微观形貌.以渗透系数和渗透通量为指标,考察了PD-PIM膜中载体含量、料液相浓度和pH,以及解析相中盐酸浓度对PD-PIM分离苯酚的影响,探讨了实验条件下苯酚通过PD-PIM的传输机制.结果表明:在实验设定的范围内,PD-PIM对苯酚的传质通量随PD-PIM中载体质量分数、料液相中苯酚浓度的增加而增大,并在料液相苯酚浓度为400 mg·L^-1、pH=6,解析相盐酸浓度为0.1 mol·L^-1,载体P204含量为70%(质量)时达到最佳分离效果.PD-PIM对苯酚的传输机制为促进耦合迁移,初期传输符合一级动力学方程.重复使用实验证实PD-PIM具有较高的稳定性.     

Cellulose acetate and sulfonated polysulfone blend ultrafiltration membranes. I. Preparation and characterization

Modification of polymeric membrane materials by incorporation of hydrophilicity results in membranes with low fouling behavior and high flux. Hence, Polysulfone was functionalized by sulfonation and ultrafiltration membranes were prepared based on sulfonated polysulfone and cellulose acetate in various blend compositions. Polyethyleneglycol 600 was employed as a nonsolvent additive in various concentrations to the casting solution to improve the ultrafiltration performance of the resulting membranes. The total polymer concentration, cellulose acetate, and sulfonated polysulfone polymer blend composition, additive concentration, and its compatibility with polymer blends were optimized. The membranes prepared were characterized in terms of compaction, pure water flux, membrane resistance, and water content. The compaction takes place within 3–4 h for all the membranes. The pure water flux is determined largely by the composition of sulfonated polysulfone and concentration of additive. Membrane resistance is inversely proportional to pure water flux, and water content is proportional to pure water flux for all the membranes. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1749–1761, 2002     

Synthesis of heteroarm star-shaped (polystyrene)n–[poly(ethyl acrylate)]m via atom transfer radical polymerization

Heteroarm star-shaped polymer, (polystyrene)_n–[poly(ethyl acrylate)]_m [(PS)_n–(PEA)_m], was synthesized in three steps. In the first step, star-shaped polystyrene, (PS)_n, was synthesized by the arm-first method via atom transfer radical polymerization (ATRP) using a preformed PS macroinitiator, which was obtained by ATRP of styrene with ethyl 2-bromoisobutyrate as the initiator, in the presence of divinyl benzene (DVB). In the microgel core of (PS)_n, there were not only a number of active initiating sites for ATRP, but also some unreacted vinyl groups. Then, in the second step, the residual vinyl groups were converted to 1-bromoethylbenzene groups by hydrobromination. In the last step, heteroarm star-shaped polymer, (PS)_n–(PEA)_m, where the arm number of PEA was greater than that of PS, was prepared by ATRP of ethyl acrylate using the hydrobrominated (PS)_n as the macroinitiator from 1-bromoethylbenzene initiating sites, obtained by both the addition of linear PS macroinitiators to vinyl groups of DVB and the hydrobromination of residual vinyl groups.     

New high permeable polysulfone/ionic liquid membrane for gas separation

In this study, the effects of 1-Ethyl-3-methylimidazolium tetrafluoroborate ionic liquid on CO₂/CH₄ separation performance of symmetric polysulfone membranes are investigated. Pure polysulfone membrane and ionic liquid-containing membranes are characterized. Field emission scanning electron microscopy (FE-SEM) is used to analyze surface morphology and thickness of the fabricated membranes. Energy dispersive spectroscopy (EDS) and elemental mapping, Fourier transform infrared (FTIR), thermal gravimetric (TGA), X-ray diffraction (XRD) and Tensile strength analyses are also conducted to characterize the prepared membranes. CO₂/CH₄ separation performance of the membranes are measured twice at 0.3 MPa and room temperature (25 °C). Permeability measurements confirm that increasing ionic liquid content in polymer-ionic liquid membranes leads to a growth in CO₂ permeation and CO₂/CH₄ selectivity due to high affinity of the ionic liquid to carbon dioxide. CO₂ permeation significantly increases from 4.3 Barrer (1 Barrer=10^-10 cm³(STP)·cm·cm^-2·s^-1·cmHg^-1, 1cmHg=1.333kPa) for the pure polymer membrane to 601.9 Barrer for the 30 wt% ionic liquid membrane. Also, selectivity of this membrane is improved from 8.2 to 25.8. mixed gas tests are implemented to investigate gases interaction. The results showed, the disruptive effect of CH₄ molecules for CO₂ permeation lead to selectivity decrement compare to pure gas test. The fabricated membranes with high ionic liquid content in this study are promising materials for industrial CO₂/CH₄ separation membranes.     

Adhesion of microorganisms to polymer membranes: a photobactericidal effect of surface treatment with TiO2

The adhesion of Escherichia coli, Pseudomonas putida and Acinetobacter calcoaceticus cells to Microdyn-Nadir ultrafiltration membranes of various chemical nature: PS100 (polysulfone), P005 (polyethersulfone), C100 (regenerated cellulose) was studied. It was shown that an adhesiveness of the microorganisms to the membranes essentially depends on hydrophobic/hydrophilic properties of both the cells and membranes. In particular, it was found that the adhesion of relatively hydrophilic E. coli to membrane surfaces is essentially lower comparing with the adhesion of more hydrophobic P. putida, or A. calcoaceticus cells. In a turn the microorganisms attachment to more hydrophobic polyethersulfone and polysulfone membranes is higher than to hydrophilic cellulose one. It was shown that the volume fluxes of membranes with adhesive microorganisms dropped while samples were kept in contact with natural surface water due to increasing of cell number on membrane surface. In attempts to reduce membrane biofouling, TiO₂ particles were deposited on membrane surface with following ultraviolet (UV) irradiation at 365 nm. It was shown that due to photobactericidal effect the fluxes of surface modified membranes were 1.7–2.3 times higher comparing with those for control membrane samples (without TiO₂ deposition and UV treatment).     

Polyurethane and sulfonated polysulfone blend ultrafiltration membranes: II. Application studies

Ultrafiltration membranes are largely being applied for macromolecular and heavy metal ion separations from aqueous streams. Polyurethane‐ and sulfonated‐ polysulfone‐based membranes prepared in the absence and presence of the polymeric additive, poly(ethylene glycol) 600, in various compositions, were subjected to the rejection of macromolecular proteins, such as bovine serum albumin, egg albumin, pepsin and trypsin. Toxic heavy metal ions such as Cu²⁺, Ni²⁺, Cd²⁺ and Zn²⁺ were subjected to rejection by the blend membranes by complexing them with a polymeric ligand, polyethyleneimine. The effects of polymer blend compositions and additive concentrations on the rejection and permeate flux of both proteins and metal ions are discussed. The rejection and permeate flux efficiencies of the blend membranes are compared with pure sulfonated polysulfone membranes. © 2003 Society of Chemical Industry     

Progress in Applications of Polymer-Based Membranes in Gas Separation Technology

Separation of gases through polymeric membrane by selective transport has immense advantages such as light weight, economical, high process flexibility, and space requirements. Fabrication methods of polymeric membrane (polysulfone, polyimide, polyamide, polycarbonate) and their properties along with fundamental principles for gas separation mechanism are discussed in this review. Polysulfone membranes are fabricated by dry/wet phase inversion process to investigate membrane properties. Polyimide membranes show great potential for gas separation and reveal good selectivity for CO₂/N₂ and CO₂/CH₄ gas pairs. Transport characteristics of polycarbonate membrane are improved by functionalization. Superior properties allow potential use of polymeric membranes in large-scale industrial applications.     

Effect of Plasticizer on Carrier-Mediated Transport of Zinc Ion through Cellulose Triacetate Membranes

Abstract

In practical applications of liquid membranes containing a mobile camer, three main types of membranes have been studied: liquid surfactant, supported liquid, and solvent polymeric membranes (2-6). In these membranes the solvent polymeric membrane which consists of a polymer film containing a plasticizer generally exhibits a low ionic permeability compared with the other types of membranes, although it has a high stability and durability. This is because the transference of the carrier in the membrane is depressed by its high viscosity and high electrical resistance. Accordingly, the ionic permeability may be improved by selecting an appropriate plasticizer.     

New one-step process for preparation of microporous composite polysulfone/polyurethane hollow-fiber membranes

Microporous composite polysulfone/polyurethane hollow-fiber membranes were prepared by using a low reactivity polyurethane prepolymer in the casting solution and precipitating the membrane in a precipitation solution containing a polymerization catalyst. The catalyst was used to promote the polymerization of prepolymer at the membrane/precipitation solution interface causing formation of an interfacial interpenetrating polymer network. As a result, an ultra-thin layer of hydrophilic polysulfone/ polyurethane composite polymer was constituted in situ on the surface of the polysulfone microporous substrate during membrane formation. Membranes with nominal pore sizes ranging from 0.1–0.45 μm were prepared using this technique. The resulting membranes exhibited excellent fluxes and very low protein adsorption characteristics.     

无皂乳液聚合法合成聚苯乙烯微球应用于准固态电解质染料敏化太阳能电池

制备了一种提高染料敏化太阳能电池短路电流和电池光电转化效率的准固态凝胶电解质,该电解质含有5%高聚物PVDF-HFP和2% TiO₂纳米颗粒。另外,通过乙醇相无皂乳液聚合法合成了大小均一的聚苯乙烯微球,并用于制备染料敏化太阳能电池的多孔光阳极。研究了准固态电解质和液态电解质应用于不同光阳极染料敏化太阳能电池的规律。结果表明,与液态电解质相反,准固态电解更适用于孔洞较多的光阳极,在相同测试条件下,电池的短路电流由12.80 mA·cm^-2提高到13.53 mA·cm^-2,效率比液态提高11.43%,达到6.63%。     

PVAm–PIP/PS Composite Membrane with High Performance for CO2/N2 Separation

Polyvinylamine (PVAm) was modified using a cross‐linking agent containing carriers piperazine (PIP). Attenuated total reflectance fourier transform infrared, elemental analyzer, and X‐ray diffraction were used to characterize the PIP‐modified PVAm. The PVAm–PIP/polysulfone (PS) composite membrane was developed by coating PVAm–PIP mixed solutions with different mass ratios of PIP/PVAm (m_PIP/m_PVAm) on the PS ultrafiltration membrane. The effects of m_PIP/m_PVAm (from 0.715 to 2.860) in the coating solutions and wet coating thickness on the gas performance of the PVAm–PIP/PS composite membrane were investigated. The PVAm–PIP/PS composite membrane prepared showed higher performance than other membranes reported in the literature due to the large increase of the introducing carrier concentration and low crystallinity. Moreover, the separation performance stability of the PVAm–PIP/PS composite membrane was investigated and no deterioration in the membrane permselectivity was observed. Finally, the economic evaluation of the membrane with the highest performance prepared was carried out. © 2012 American Institute of Chemical Engineers AIChE J, 59: 215–228, 2013     

聚偏氟乙烯共混膜的制备和性能研究

主要讨论了聚偏氟乙烯(PVDF)膜以及聚甲基丙烯酸甲酯(PVDF/PMMA)、PVDF/PMMA/PS(聚砜)共混膜的制备及性能,并研究了不同添加剂对PVDF/PMMA/PS共混膜的结构和性能的影响。实验数据表明:PVDF/PMMA/PS共混膜的通量最大;PVPK 40成膜通量最大;T iO 2成膜截留率最大。