聚砜/聚苯胺-嵌段式聚醚Pluronic F127复合超滤膜的制备及性能

选用具有不同改性机理的嵌段式聚醚Pluronic F127与聚苯胺(PANI)纳米纤维共同作为添加剂共混改性聚砜(PSf)超滤膜,利用浸没沉淀相转化法制备出PSf/PANI-F127复合超滤膜。考察、比较并分析两种改性材料同时存在对膜结构和膜性能的影响。膜结构通过傅里叶衰减全反射红外(ATR-FTIR)、X射线光电子能谱(XPS)、X射线能量色散谱(EDS)、扫描电镜(SEM)和接触角等测试表征。膜性能通过纯水通量、截留率、抗污染性能以及添加剂稳定性结果进行评价。实验结果表明,Pluronic F127的加入可以更有效地提高膜表面亲水性,而PANI纳米纤维的加入则可以使膜孔隙率增大、表面孔径尺寸降低、皮层变薄。实验进一步发现,两种添加剂在改善膜结构与性能上起协同作用。PANI-F127一方面提高了膜纯水通量与抗污染性能,另一方面克服了单独使用Pluronic F127时添加量大、截留率低、添加剂易流失的缺点。     

聚砜超滤膜的制备及结构性能研究

实验以低分子量的PEG作为添加剂制备聚砜超滤膜,通过不同低分子量和不同含量的PEG加入,改变了膜结构性能。制膜液由聚砜(PSf)/二甲基乙酰胺(DMAc)/聚乙二醇(PEG)组成。通过水通量、截留率和电镜图来评价添加剂对膜的性能结构影响。     

Fe3O4磁性颗粒对聚砜超滤膜性能的影响

采用相转化法,制备不同纳米Fe3O4含量的PS-Fe3O4超滤膜,用扫描电镜观察Fe3O4颗粒的分布情况,并用磁强测量系统(MPMS)测量共混膜的磁性,以及通过对α-淀粉酶的超滤考察共混膜在磁场下截留率可以变化的特性.结果表明:PS-Fe3O4共混膜具有超顺磁性;膜的孔隙率、水通量、截留率随着Fe3O4含量的增高而增加;但当Fe3O4含量提高到25％时,易使膜产生结构缺陷,故确定较优Fe3O4添加量为20％.在磁场作用下,PS-Fe3O4超滤膜的截留率发生变化,随着Fe3O4含量的增高,磁变化效应增强.在0.4T的磁场下,共混膜中FeO4含量为5％,10％,15％,20％时,对α-淀粉酶的截留率分别比不在磁场中降低了3.5％,7.4％,12.3％,18.2％,表明Fe3O4磁性颗粒的添加不仅能改善膜的性能,而且能使膜具备截留率可调的特性.     

高通量聚醚砜纳滤膜的制备及对染料浓缩脱盐

以聚醚砜（PES）为膜材料,以嵌段式聚醚 Pluronic F127为添加剂,利用特制刮膜设备通过相转化法制备出高通量PES/Pluronic F127复合纳滤膜,并将其用于染料的浓缩脱盐。研究了添加剂含量、溶剂蒸发温度和蒸发时间对膜结构和膜性能的影响,考察了不同操作压力和操作温度下膜对染料的分离性能。扫描电镜 （SEM）、接触角、孔隙率数据和蛋白吸附测试结果表明,Pluronic F127改善了膜孔结构,提高了孔隙率,并且显著提高了膜的抗污染性能。纯水通量、截留率以及膜表面孔径表征结果表明,当Pluronic F127含量为3%、溶剂蒸发温度为90℃、 蒸发时间为18 s时,膜的分离性能最佳。在0.6 MPa下该膜对低分子量染料的截留率可达99.9%,且通量达到110.2 L·m^-2·h^-1,对NaCl的截留率仅为5.5%。在12 h的染料浓缩脱盐中,膜对染料的通量维持在较高水平且截留率始终保持在99%左右,具有良好的稳定性和抗污染性。     

添加剂对PVDF平板超滤膜性能和结构的影响

分别以无水氯化锂(LiCl),磷酸(H_3PO_4)为添加剂,采用正交试验设计方法优化PVDF平板超滤膜制备条件.以去离子水为凝胶浴,考察了聚合物浓度、溶剂种类、添加剂含量对超滤膜平均孔径,孔隙率等膜结构特征殁膜纯水通量、BSA截留率的影响.结果表明,对于LiCl体系,影响膜孔隙率的制膜条件是:LiCl浓度>溶剂种类>PVDF浓度,制膜液组成为12% PVDF/DMAC/5%LiCl时孔隙率最高,达到86.42%;对于H_3PO_4体系,影响膜孔隙率的制膜条件是:溶剂种类>H_3PO_4浓度>PVDF浓度,制膜液组成为15%PVDF/NMP/5%H_3PO_4时孔隙率最高,达到85.86%;对于LiCl和H_3PO_4体系,影响膜孔径的因素均为:PVDF浓度>溶剂种类>添加剂浓度,最大孔径下的最佳制膜液组成为12%PVDF/NMP/3%添加剂.研究得出LiCl体系和H_3PO_4体系的最佳组合分别为18PVDF/NMP/3%LiCl和15%PVDF/NMP/5%H_3PO_4.     

添加剂对聚砜膜结构和性能的影响

通过浸没沉淀相转化法制备聚砜超滤膜,分别以高分子聚乙烯基吡咯烷酮（PVP-K30,PVP-K90）、聚乙二醇（PEG-6000,PEG-20000）和小分子氯化锌（ZnCl2）、丙酸（AS）6种物质作为制备聚砜超滤膜的添加剂,含量均为10%。并对聚砜超滤膜的断面结构、纯水通量、牛血清蛋白（BSA）截留率、孔隙率及平衡水含量等5项性能进行了测试及表征。由断面结构可以看出,PVP-K90作为添加剂时,制得膜的断面完全为海绵状结构,其它添加剂制得膜断面中均有指状孔结构;PVP-K30作为添加剂时制得膜的纯水通量最大;丙酸作为添加剂制得膜的BSA截留率最高;聚乙烯基吡咯烷酮（PVP）和聚乙二醇（PEG）制得膜的平衡水含量及总孔隙率均较高,但闭孔也较多。     

负载纳米银的埃洛石纳米管/聚醚砜杂化超滤膜的制备

以聚醚砜(PES)为膜材料,N, N-二甲基乙酰胺(DMAc)为溶剂,聚乙烯吡咯烷酮(PVP)和负载纳米银的埃洛石纳米管(Ag- HNTs)为添加剂,采用相转化法制备聚醚砜超滤膜。系统地考察了添加剂(Ag- HNTs)含量对膜性能的影响,并用抑菌圈试验研究了所制膜的抗菌效果。结果表明：硅烷偶联剂KH-792中的甲氧基与HNTs上的羟基成功地发生反应,并且接枝量为0.105g (KH-792)?g -1 (HNTs);改性后的HNTs与Ag成功地发生络合反应,并且络合量近似为0.145g (Ag)?g -1 (HNTs);溶剂中负载纳米银的埃洛石纳米管(Ag- HNTs)所占比例的增加能提高膜的水通量,而截留率保持在95%左右。所制备的膜对大肠杆菌和金黄色葡萄球菌有较强的抑制作用。     

Clay-hyperbranched epoxy/polyphenylsulfone nanocomposite membranes

Nanocomposite membranes containing polyphenylsulfone (PPSU) and a clay modified with a hyperbranched epoxy (HBE) were prepared by blending of modified montmorillonite (m-MMT) with a polymer solution using phase inversion method. The hyperbranched epoxy synthesized by polycondensation reaction of bisphenol A and triethanolamine with epichlorohydrin was grafted to amine-functionalized MMT by reaction between the epoxy groups of hyperbranched epoxy and the amine groups on the MMT surface. In this way, the m-MMT was exfoliated into single layers of nanoparticles in a solvent medium and the polymer chains were intercalated into m-MMT layers. The aim was to study the effect of this additive on the membrane separation efficiency. For this purpose, pure water flux, fouling, and pigment and heavy metal rejection were measured by a home-made dead end filtration cell and the performance of the prepared membranes was investigated. Hydrophilicity of the nanocomposite membranes was specified by water contact angle measurements. Degree of dispersion of additive into the polymer matrix and membrane morphology were studied by FESEM. Membrane surface area, pore size, and volume were evaluated by BET. The results indicated that the surface hydrophilicity increased after incorporation of m-MMT. Furthermore, the water permeability, salt rejection, and antifouling resistance of PPSU membranes were improved significantly. Membrane with 3 wt% m-MMT showed the best performance compared to other membranes.     

Solute rejection by porous glass membranes. III. Reduced silica dissolution and prolonged hyperfiltration service with feed additives

It was found that inclusion of 0.3 g/l AlCl₃,6H₂O as a feed additive in hyperfiltration tests was sufficient to stabilise a porous glass membrane (batch A-1) with relatively high volume flux and modest solute rejection characteristics. One-tenth of this concentration was not sufficient. Further testing was directed toward treatment of porous glass membranes with concentrated aluminium chloride solution for a limited time, followed by hyperfiltration with a dilute feed additive. As little as 0.003 g/l AlCl₃,6H₂O stabilised batch A-1 for 80 h; while batch A-5, with lower volume flux and higher solute rejection characteristics, could be stabilised with no feed additive but only treatment with a concentrated aluminium solution every 100 h. Other experiments showed a similar equilibrium silica solubility, about 110 parts/million, in all solutions regardless of AlCl₃, HC₁, NaCl, or urea addition. The test which showed rates of silica dissolution revealed, however, that both low pH and aluminium lowered the rate of solution. The effectiveness of porous glass membrane stabilisation by aluminium treatment or reduced pH was also reflected in greatly reduced silica concentration of the effluent from hyperfiltration tests. Treatment of porous glass membranes with ferric and zirconyl chlorides was also tested, but aluminium chloride was the most effective in reducing silica loss. Chemical analysis of treated and tested membranes showed that aluminium remained in the pore structure in concentrations comparable to that of reactive silica hydroxyls. This is greater than the apparent concentration of ion exchange sites, and considerably less than total free hydroxyl concentration. Since suitable aluminium treatment or feed additive maintains membrane flux, rejection, and pore size characteristics, despite loss of soluble silica in the effluent, it appeared that added aluminium was retained in the membrane structure in amounts equivalent to the dissolved silica.     

Acrylonitrile–maleic anhydride copolymer membranes with different molecular weights

The structure and performance of acrylonitrile–maleic anhydride copolymer membranes with different molecular weights were investigated. The results showed that the water flux of the membrane decreased gradually with increasing molecular weight of the copolymer; the rejection increased only when there was an obvious increase of molecular weight. The addition of an additive (polyvinylpyrrolidone) largely decreased the water flux and rejection of the membrane when the concentration of the copolymer remained unchanged. The higher the molecular weight, the thicker were the transition layer and the wall of the support pore and the better was the anticompactness of the membrane. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2521–2527, 2002     

Tuning the morphology of PVDF membranes using inorganic clusters for oil/water separation

Polyvinylidene fluoride (PVDF) membranes with modified membrane morphology were prepared by phase inversion process using iron alkoxide as a novel pore-forming additive (PFA). Higher pure water flux was observed for PVDF/PFA (iron alkoxide) membranes treated with 5% HCl, due to higher porosity produced by the leaching out of the iron alkoxide additive. The untreated membrane containing 0.04% iron alkoxide showed ~99% efficiency oil removal from a surfactant-stabilized oil–water emulsion. After acid treatment, there was a slight decrease in the rejection efficiency (~96.5%); however, this membrane still exhibited the highest emulsion flux. The fouling propensity of the membrane with 0.04 wt % iron alkoxide tested in a crossflow condition decreases indicating a lower amount of oil adsorbed onto the surface and a greater flux recovery ratio. The treated membranes showed appreciable anti-biofouling property when the membranes were challenged with Escherichia coli and Bacillus subtilis obtained from freshwater and/or seawater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47641.     

Synthesis and characterization of polyethersulfone membranes

Phase inversion method was used to prepare polyethersulfone (PES) ultrafiltration (UF) membranes. Polyethylene glycol (PEG); N, N-dimethyl formamide (DMF) and water were utilized as pore-forming additive, solvent and non-solvent, respectively. Effects of PES and PEG concentrations in the casting solution, PEG molecular weight (MW) and coagulation bath temperature (CBT) on morphology of the prepared membranes were investigated. Taguchi experimental design was applied to run a minimum number of experiments. 18 membranes were synthesized and their permeation and rejection properties to pure water and human serum albumin (HSA) solution were studied. It was found out that increasing PEG concentration, PEG MW and CBT, accelerates diffusional exchange rate of solvent (DMF) and non-solvent (water) and consequently facilitates formation of macrovoids in the membrane structure. The results showed that, increasing PES concentration, however, slows down the demixing process. This prevents instantaneous growth of nucleuses in the membrane structure. Hence, a large number of small nucleuses are created and distributed throughout the polymer film and denser membranes are synthesized. A trade-off between water permeation and HSA rejection was involved, with membranes having higher water permeation exhibited lower HSA rejection, and vice versa. Hence, optimizing preparation variables to achieve high pure water permeation flux along with reasonable HSA rejection was inevitable. Analysis of variance (ANOVA) showed that all parameters have significant effects on the response (water flux and HSA rejection). However, CBT and PES concentration were more influential factors than PEG concentration and MW on the responses.     

Role of Organic Acids in Flux Enhancement of Polyamide Nanofiltration Membranes

A novel thin‐film composite (TFC) nanofiltration membrane containing hydrophilic organic additives was fabricated via interfacial polymerization. Three organic acids, i.e., lactic, maleic, and citric acid, served as aqueous‐phase additives and their role in membrane structure and nanofiltration membrane flux enhancement was investigated. Fourier transform‐infrared (FT‐IR) analysis confirmed the presence of organic acids in the polyamide (PA) layer. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses were applied to investigate the membrane morphology. The more carboxylic functional groups present in the additive resulted in higher hydrophilicity and porosity and flux was enhanced significantly compared to the neat PA membrane, while salt rejection was influenced only to a minor extent.     

Influence of membrane support structure on the efficiency of an iron-modified silica nanofiltration membrane

Inorganic membranes are generally created by depositing a thin film separation (membrane) layer atop a supporting structure in order to provide for the physical durability of the membrane. The separation layer thickness and morphology are normally evaluated to determine their contribution to fluid flow resistance across the membrane. The supporting structure is often ignored, yet can affect the quality of the membrane formed and significantly influence the global efficiency of the membrane module. In this paper, three different support structures are compared and evaluated with respect to the efficiency (rejection and flux) of an iron-modified silica separation layer. The main difference in the supports was the nominal pore size of the surface responsible for facilitating the membrane layer. The pore sizes of the supports investigated were 5, 10, and 20 nm in diameter. It was hypothesized that the largest pore size support would produce a higher water flux. However, this support did not provide an adequate surface for the deposition of a high quality membrane layer. The formation of an intact membrane layer was successfully achieved using the other two support structures. From the results obtained from salt rejection and flux data of these two functional membrane modules, the influence of the support structure on the overall efficiency of the membrane module was assessed. The 10 nm support structure produced a water flux that was 1.6 times greater than that of the 5 nm pore size support, without sacrificing the rejection of the electrolytes studied.     

Taurine as an additive for improving the fouling resistance of nanofiltration composite membranes

A hydrophilic compound, taurine, was investigated as an additive in the interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC) to prepare thin‐film composite (TFC) membranes. The resulting membranes were characterized by X‐ray photoelectron spectroscopy and attenuated total reflectance–Fourier transform infrared spectroscopy. The morphology and hydrophilicity of the membranes were investigated through scanning electronic microscopy and water contact angle measurements. The separation performance of the TFC membranes was investigated through water flux and salt rejection tests. The protein‐fouling resistance of the films was evaluated by water recovery rate measurements after the treatment of bovine serum albumin. The membrane containing 0.2 wt % taurine showed the best performance of 92% MgSO₄ rejection at a flux of 31 L m^?2 h^?1 and better antifouling properties than the PIP–TMC membranes. An appropriately low concentration of taurine showed the same MgSO₄ rejection as the PIP–TMC membranes but a better fouling resistance performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41620.     

Key factors affecting the manufacture of hydrophobic ultrafiltration membranes for surface water treatment

As part of the development of poly(ether sulfone) (PES) membranes whose surface is modified by the incorporation of a newly synthesized hydrophobic surface modifying macromolecule (nSMM) additive, this study investigates the impact of four key membrane preparation factors. They are concentration of PES, concentration of nSMM, casting thickness, and casting speed. The synthesis and characterizations of nSMM by nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimeter, and elemental analysis have been presented. The changes in characteristics and performance of the membranes have been evaluated via Fourier transform infrared spectroscopy, contact angle analysis, scanning electron microscopy, and solute transport tests. The addition of 0.5 wt % of nSMM increased the contact angle of PES membranes by 20°; however, higher nSMM concentrations did not increase the hydrophobicity any further. Only the additive concentration had a statistically significant impact on flux reduction and dissolved organic carbon rejection. Even though other factors such as membrane thickness may alter the pore characteristics, their effect on membrane performance was marginal. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

膜分离法处理低浓度含锌废水的实验研究

通过考察膜分离过程中各操作条件对分离效果的影响,特别是低压操作条件下RO和强化UF膜分离过程中,添加剂种类和含量、重金属浓度、膜操作压力、反应时间对膜分离过程的截留率、渗透通量等的影响,为该技术的应用和推广提供理论支持。     

PVPK30和Tween80对中空纤维超滤膜结构和性能的影响

通过考察添加剂-聚乙烯吡咯烷酮（PVPK30）和Tween80对杂萘联苯聚醚砜酮（PPESK）中空纤维超滤膜结构和分离性能的影响，发现：随高分子添加剂聚乙烯吡咯烷酮K30浓度的升高，膜水通量减小，截留率基本无变化，膜结构逐渐由指状结构转变成海绵状结构。有机大分子添加剂Tween80可以提高膜的水通量，但膜结构不随添加剂浓度而改变，均为指状结构。当Tween80浓度小于5wt％时，随Tween80浓度的增加，膜水通量升高，截留率下降。比较不同凝胶浴温度下的膜分离性能可以看到，凝胶浴温度提高可以显著提升膜的纯水通量。     

Effects of coagulation bath temperature and polyvinylpyrrolidone content on flat sheet asymmetric polyethersulfone membranes

In this study, effects of coagulation bath temperature (CBT) and polyvinylpyrrolidone (PVP K15) concentration as a pore former hydrophilic additive on morphology and performance of asymmetric polyethersulfone (PES) membranes were investigated. The membranes were prepared from a PES/ethanol/NMP system via phase inversion induced by immersion precipitation in a water coagulation bath. The morphology of prepared membranes was studied by scanning electron microscopy (SEM), contact angle measurements, and mechanical property measurements. Permeation performance of the prepared membranes was studied by separation experiments using pure water and bovine serum albumin (BSA) solution as feed. The obtained results indicate that addition of PVP in the casting solution enhances pure water permeation flux and BSA solution permeation flux while reducing protein rejection. Increasing CBT results in macrovoid formation in the membrane structure and increases the membrane permeability and decreases the protein rejection. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Highly improved permeation property of thin-film-composite polyamide membrane for water desalination

Thin-film-composite (TFC) polyamide membranes with flux-enhancement were prepared by the interfacial polymerization of m-phenylenediamine with trimesoyl chloride on porous polysulfone support. The addition of 1,3-propanesultone (PS) in the organic phase is used to influence the interfacial polymerization process and the morphology of polyamide layer to improve water flux. FTIR, ¹H NMR and UV spectra were performed to investigate the effect of PS on interfacial polymerization process. In order to study the forming mechanism of TFC membrane, the resulting TFC membranes were characterized by SEM, AFM, ATR-FTIR, XPS, as well as static contact angle. In comparison with conventional polyamide membrane, the TFC membranes fabricated with PS as the additive exhibit much more improved water flux without NaCl rejection decreasing. Notably, the optimal TFC membrane with 0.04% (wt/v) PS as the additive in organic phase shows the best performance with a NaCl rejection of 99.39% and a water flux of 48.57 L m^?2 h^?1 at 1.55 MPa, which has increased 41% compared to the value of the conventional TFC membrane.