γ-BL/TEP混合溶剂对PVDF膜结构和性能的影响

通过溶解度参数预测,膜渗透性能检测,及扫描电镜(SEM)对膜形貌观察,考察了聚偏氟乙烯(PVDF)在γ-丁内酯(γ-BL)、磷酸三乙酯(TEP)为混合溶剂,乙二醇(EG)、N,N-二甲基乙酰胺(DMAc)及其混合物为凝固浴时,相转化条件及溶剂配比对PVDF膜在孔隙率、纯水通量、BSA截留率,以及拉伸强度等性能方面的影响行为。结果表明,随混合溶剂中TEP质量分数的增加,凝胶浴中溶剂DMAc质量分数增大,PVDF膜皮层逐渐变薄,PVDF结晶球粒粒径变小,孔隙率增加,拉伸强度下降。当混合溶剂中TEP的质量分数为60%,凝胶浴DMAc含量30%时,膜纯水通量达2 100 L/(m2·h),BSA截留率仍保持58.7%,具有良好的超滤性能,可作为制备高通量、较高截留PVDF超滤膜的最佳条件。     

磺化聚三氟苯乙烯对不同溶剂体系制备聚砜超滤膜结构及性能影响研究

本文以聚砜(PSF)为膜材料，磺化聚三氟苯乙烯(SPTFS)为改性剂，采用不同溶剂N,N-二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)、N-甲基吡咯烷酮(NMP)制备了改性聚砜膜。采用扫描电镜、接触角测量仪、孔径分析仪和死端过滤系统研究SPTFS和溶剂对膜结构和性能的影响。研究表明，SPTFS的引入能够改变膜结构，SPTFS改性膜由纯聚砜膜的指状孔结构转变为胞腔状孔或海绵状孔结构。同时，SPTFS能够改善聚砜膜的渗透性能，以DMAc、DMF、NMP为溶剂改性的聚砜膜水通量分别提升了618.7、127.5、194.0 L/(m²·h),同时蛋白质截留率均高于97%,显示出优异的分离性能。     

凝固浴组成和温度对PVDF疏水微孔膜结构与性能的影响

利用非溶剂相转化法(NIPS),以聚偏氟乙烯(PVDF)/磷酸三乙酯(TEP)-N,N-二甲基乙酰胺(DMAc)为铸膜液体系,乙醇水溶液为凝固浴制备高性能的PVDF疏水微孔膜。考察了凝固浴中乙醇(EtOH)含量及凝固浴温度对PVDF成膜分相速率、膜结构和膜疏水性的影响。实验结果表明,在20℃的凝固浴温度下,凝固浴中乙醇含量的升高减慢了铸膜液体系的分相速率,提高了PVDF膜的孔隙率;在凝固浴中添加60%(wt)的乙醇,可形成表面荷叶状结构和截面对称的海绵状结构,膜表面的接触角为130.3°,呈很强的疏水性,并具有较优的膜强度。     

聚砜超滤膜结构对铸膜溶液性质的依赖性

考察了聚砜(PSF,在N-甲基吡咯烷酮(NMP)、N,N-二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)三种溶剂中的链尺寸,铸膜液的零切粘度和浊点等,用场发射扫描电镜(SEM)对膜的表面形貌和截面结构进行了表征.结果表明,PSF在三种溶剂中链尺寸大小为NMP>DMAc>DMF,与PSF在三种溶剂中耐非溶剂水的能力顺序相同.当PSF浓度为13%时,相对粘度和流动活化能大小的顺序为DMF>DMAc>NMP.以DMF为溶剂制备的膜截面为具有密度梯度的网络状孔,而以DMAc和NMP为溶剂得到的膜为指状孔.不同溶剂对膜结构,水通量和截留率有显著影响.     

溶剂/非溶剂体系对聚醚砜微孔膜性能和结构的影响

以N,N-二甲基乙酰胺(DMAc)、N-甲基吡咯烷酮(NMP)和N,N-二甲基甲酰胺(DMF)为溶剂,乙醇(EtOH)、异丙醇(IPA)、正丁醇(BuOH)、一缩二乙二醇(DegOH)、聚乙二醇400(PEG400)为非溶剂添加剂,研究了溶剂/非溶剂体系对聚醚砜(PES)膜的结构和性能的影响.改变铸膜液体系中的非溶剂含量对膜的结构和性能有很大影响,但是这种影响不是以非溶剂的绝对含量来衡量的,而取决于非溶剂/溶剂的比值.改变溶剂的组成和配比也改变了溶剂/非溶剂体系,体系的溶度参数越接近PES的溶度参数,与PES的相容性越好,但是膜的通量较小.实验结果表明,采用NMP(或DMAc)与DMF以适当比例混合作溶剂,比采用单一NMP(或DMAc)作为溶剂制得的膜通量要大.通过改变溶剂配比,可实现对膜的表面开孔率、孔径、断面结构等参数的微控.     

织布支撑PVDF—纳米TiO2共混膜在MBR中抗污染性能研究

在室温25℃、压力50 kPa条件下,将尼龙织布作为支撑层,以聚偏氟乙烯(PVDF)和N,N-二甲基乙酰胺(DMAc)为主要原料制备PVDF膜,并在体系中添加2种不同含量的纳米TiO2制备PVDF-TiO2共混膜,其纯水通量分别为4 892、3 752、2 437 L.m-.2h-1。通过膜生物反应器中膜阻力的测定,表明膜污染主要由沉积层引起。在MBR中运行时,3种膜的膜通量衰减速率分别为0.112 3、0.089 0、0.075 9,纳米TiO2含量高的PVDF-TiO2膜通量衰减最慢、抗污染性最好、膜截留作用最高。     

不同铸膜液成分对PES/PVDF膜结构与性能影响的研究

采用浸没沉淀相转化法,以二甲亚砜(DMSO)、磷酸三乙酯(TEP)及二甲基乙酰胺(DMAC)作为铸膜溶剂,制备聚醚砜(PES)/聚偏氟乙烯(PVDF)共混膜,研究不同铸膜液成分对膜结构与性能的影响。通过膜的纯水通量、孔隙率、接触角等表征膜性能。利用有机添加剂N-甲基吡咯烷酮(NMP)、聚乙烯吡咯烷酮(PVP)改变PES/PVDF共混膜的性能,结果表明无机添加剂可增大其纯水通量和孔隙率并改善其亲水性。     

混合稀释剂制备PVDF微孔膜的结构与性能研究

以邻苯二甲酸二甲酯(DMP)和N,N-二甲基乙酰胺(DMAc)作为混合稀释剂,采用复合热致相分离法制备聚偏氟乙烯(PVDF)微孔膜,并用扫描电镜、差示扫描量热分析仪、拉伸压缩材料试验机等测试仪器对微孔膜结构和性能进行了研究。结果表明:随着PVDF含量增加,体系的结晶度下降;随着混合稀释剂中DMP含量增加,膜强度先增大后减小,而水通量增加,截留率减小;冷却速率对孔隙率影响不大,但冷却速率减小,水通量增加,而截留率下降;DMAc与DMP质量比为1/2时,膜强度以及水通量均比单纯采用DMP做稀释剂时的好,前者的水通量达247 L/h.m2,比后者的增加了28%。     

低临界共溶温度PES体系制备微孔膜的研究

以聚醚砜(PES)/N,N-二甲基乙酰胺(DMAc)/一缩二乙二醇(DEG)低临界共溶温度(LCST)体系为铸膜液,利用低临界共溶温度(LCST)的热致相分离(LCST-TIPS,简称RTIPS)法制备了PES微孔膜。通过透光实验测试RTIPS过程的LCST,以扫描电镜、渗透和力学实验表征膜的形态和性能。研究了非溶剂/溶剂(DEG:DMAc)质量比和成膜水浴温度对PES膜结构和性能的影响。实验结果表明,随DEG:DMAc质量比增加,相分离温度降低;利用RTIPS技术抑制了膜断面指状孔的出现,形成表面有明显微孔和断面对称的双连续膜结构;DEG:DMAc质量比0.8:1,成膜水浴温度60℃,膜纯水通量和平均孔径最大;通过RTIPS机理所成膜综合力学性能优于非溶剂致相分离(NIPS)法所制备的膜。     

凝固浴组成对PVDF/PVDF-g-PAA共混膜结构与性能的影响

为了进一步提高PVDF膜的亲水性及渗透性能,本文通过在膜内引入聚偏氟乙烯接枝聚丙烯酸(PVDF-g-PAA),提高共混膜的亲水性,并在凝固浴中加入N, N-二甲基乙酰胺(DMAc),改善聚偏氟乙烯/聚偏氟乙烯接枝聚丙烯酸(PVDF/PVDF-g-PAA)共混膜的结构与性能。利用浊点法对PVDF/PVDF-g-PAA共混膜的成膜热力学进行了研究,相比于水/乙醇凝固浴,水/DMAc凝固浴的使用会抑制PVDF/PVDF-g-PAA的相分离速度,体系变得更加稳定。采用傅里叶红红外光谱仪(FT-IR)和X-射线光电子能谱仪(XPS)表征聚合物及膜的化学结构,并通过原子力显微镜和扫描电镜观察膜的表断面结构。结果表明,随着凝固浴中DMAc含量的增加,膜的致密皮层逐渐变薄,膜断面中的指状孔结构逐渐向海绵状结构转变,膜表面变粗糙,平均孔径增加,共混膜纯水通量变大。当DMAc含量为50%时,膜的纯水通量最高,可达(1 084±74)L/(m~2·h),同时具备较高的断裂强度(2.6±0.1)MPa。     

Effects of mixed solvents and PVDF types on performances of PVDF microporous membranes

Polyvinylidene fluoride (PVDF) microporous flat membranes were cast with different kinds of PVDFs and four mixed solvents [trimethyl phosphate (TMP)–N,N‐dimethylacetamide (DMAc), triethyl phosphate (TEP)–DMAc, tricresyl phosphate (TCP)–DMAc, and tri‐n‐butyl phosphate (TBP)–DMAc]. The effects of different commercial PVDFs (Solef® 1015, FR 904, Kynar 761, Kynar 741, Kynar 2801) on membrane morphologies and membrane performances of PVDF/TEP–DMAc/PEG200 system were investigated. The membrane morphologies were examined by scanning electron microscopy (SEM). The membrane performances in terms of pure water flux, rejection, porosity, and mean pore radius were measured. The membrane had the high flux of 143.0 ± 0.9 L m^?2 h^?1 when the content of TMP in the TMP–DMAc mixed solvent reached 60 wt %, which was 2.89 times that of the membrane cast with DMAc as single solvent and was 3.36 times that of the membrane cast with TMP as single solvent. Using mixed solvent with different solvent solubility parameters, different morphologies of PVDF microporous membranes were obtained. TMP–DMAc mixed solvent and TEP–DMAc mixed solvent indicated the stronger solvent power to PVDF due to the lower solubility parameter difference of 1.45 MPa^1/2 and the prepared membranes showed the faster precipitation rate and the higher flux. The less macrovoids of the membrane prepared with TEP (60 wt %)–DMAc (40 wt %) as mixed solvent contributed to the higher elongation ratio of 96.61% ± 0.41%. Therefore, using TEP(60 wt %)–DMAc (40 wt %) as mixed solvent, the casting solution had the better solvent power to PVDF, and the membrane possessed the excellent mechanical property. The microporous membranes prepared from casting solutions with different commercial PVDFs exhibited similar morphology, but the water flux increased with the increment of polymer solution viscosity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

凝固浴温度对PVDF/PES-C共混膜结构及性能的影响

以邻苯二甲酸二丁酯(DBP)和N,N-二甲基乙酰胺(DMAc)为混合稀释剂,采用热致相分离法(TIPS)制备了聚偏氟乙烯(PVDF)/酚酞型聚醚砜(PES-C)共混膜,考察了不同凝固浴温度对膜结构和性能的影响。采用扫描电镜观察了膜的结构,测试了膜的纯水通量。运用DSC和XRD方法检测了膜的结晶性能。将制备的膜在膜生物反应器(MBR)中运行测试了膜的污水通量和出水指标。随凝固浴温度的升高,共混膜的最高熔融温度上升,膜中α晶型的含量增加。在凝固浴温度为25℃时,膜形成了较为致密的皮层结构和较为疏松的支撑层结构,此时共混膜的纯水通量和污水通量达到最大值,且MBR出水COD和NH4+-N含量达到排放要求。     

Preparation and characterization of polysulfone–cyclodextrin composite nanofiltration membrane: Solvent effect

α-Cyclodextrin membranes were prepared by the phase inversion method using four types of casting solvents such as N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethyl acetamide (DMAc), and dimethyl formamide (DMF) herein-after termed as α-CD-NMP, α-CD-DMSO, α-CD-DMAc, and α-CD-DMF, respectively. The membranes were characterized by IR, XRD, TGA-DTA, DSC, and SEM analysis and show that solvents like NMP, DMA, DMF give good uniform morphological membranes and are better than that of DMSO. Thermal decompositions of the pure polymer and composite membranes indicate different range of thermal degradation of the membrane. This study reveals that the casting solvents NMP, DMF, DMAC have nearly same significant effect on morphology and other properties of the membranes. This is explained in terms of demixing behavior of the polymer and the combined effect of solvent volatility and polymer–solvent interactions as estimated from Hansen solubility parameter. Solvent hydrophobicity also affects the performance of the membrane and can be determined in terms of water permeability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

PVDF/PES-C共混膜的结构与性能

以邻苯二甲酸二丁酯(DBP)和N,N-二甲基乙酰胺(DMAc)为混合稀释剂,采用热致相分离法(TIPS)制备了聚偏氟乙烯(PVDF)和酚酞型聚醚砜(PES-C)共混膜,采用扫描电镜观察了膜的截面结构,测试了膜的纯水通量。通过膜生物反应器处理生活污水,检验了膜的污水处理性能。与PVDF膜相比,共混膜具有一个较薄的致密的皮层和较为疏松的支撑层,共混膜的纯水通量约为纯聚偏氟乙烯膜的两倍。同时共混膜的污水通量较高,COD和NH4+-N的去除率与PVDF膜相比约增加10%,共混膜的通量衰减系数较小,具有更好的抗污染性能。     

酚酞型聚醚砜对聚偏氟乙烯中空纤维膜结构及性能的影响

以二苯甲酮和N,N-二甲基乙酰胺为稀释剂,酚酞型聚醚砜(PES-C)为添加剂,通过热致相分离法制备了聚偏氟乙烯(PVDF)中空纤维膜。采用扫描电镜观察了膜的结构,测试了膜的纯水通量。在膜生物反应器(MBR)中测试了膜的污水通量和出水的化学需氧量及氨氮指标。该法制得的膜具有较为致密的皮层结构和疏松的支撑层结构,添加质量分数为2%的PES-C制备的PVDF膜与PVDF膜相比纯水通量增加60%,污水通量增加37.8%,出水COD去除率增加了3.32%,NH4+—N去除率增加了2.2%,且MBR出水达到排放标准。     

Studies on fouling by natural organic matter (NOM) on polysulfone membranes: Effect of polyethylene glycol (PEG)

Polysulfone membranes were prepared via phase inversion technique by using polyethylene glycol with molecular weights of 400, 1500 and 6000 Da as pore forming agent in dope formulation. The performance of membrane was characterized using humic acid and water sample taken from Sembrong River, Johor, Malaysia was used as natural organic matter sources. Membrane properties were also characterized in terms of mean pore radius, pure water flux, humic acid rejection and fouling resistance. The results indicated that the pure water flux and mean pore radius of membranes increased with the increase of PEG content. Fourier transform infrared spectroscopy results revealed the presence of hydrophilic component in PSf/PEG blend with the significant appearance of O–H peak at 3418.78 cm^− 1. Scanning electron microscopy analysis revealed the presence of finger-like structure for all membranes and the structure intensified as PEG content was increased. The results obtained from the fouling study indicated that the membrane with the lowest PEG content and molecular weight has an excellent performance in mitigating fouling.     

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。     

混合稀释剂对热致相分离法制备聚偏氟乙烯膜性质及结构的影响

采用邻苯二甲酸二丁酯(DBP)为稀释剂,通过加入部分N,N-二甲基乙酰胺(DMAc)或邻苯二甲酸二辛酯(DOP),分别在150℃和220℃下,采用热致相分离法制备了聚偏氟乙烯(PVDF)平板膜,研究了在较低温度下或高温下制得膜的性能和结构。结果表明,加入质量分数10%的DMAc在150℃下制膜,比采用纯的DBP为稀释剂时膜的通量提高了28%,过多DMAc的加入反而会使膜的通量降低;加入质量分数10%的DOP在220℃下制膜,膜的通量则下降了62%。同时采用扫描电镜观察了膜的截面结构,解释了采用不同混合稀释剂时膜形成不同结构的原因。     

Poly(vinyl chloride) Asymmetric Membrane Modified with Poly (ethylene glycol): Effect of Additive Concentration on the Morphology and Performance

Asymmetric membranes of polyvinyl chloride modified with polyethylene glycol as pore former have been prepared by nonsolvent-induced phase separation method using N,N-dimethylacetamide/water as solvent/nonsolvent system. The phase diagram of polyvinyl chloride/polyethylene glycol/N,N-dimethylacetamide/water system showed that polyethylene glycol favors the demixing process. The prepared membrane is characterized by scanning electron microscopy, ATR-FTIR, equilibrium water content, porosity, pure water flux, and contact angle. The addition of polyethylene glycol favored the formation of finger-like structure of polyvinyl chloride membrane initially, and at higher polyethylene glycol concentration, a spongy structure is obtained. The prepared membrane possesses high water flux, excellent thermal stability, and sufficient mechanical strength suitable for ultrafiltration operation.