TEOS交联EVAL膜的制备及其油水分离性能

用四乙氧基硅烷(TEOS)对聚(乙烯-乙烯醇)(EVAL)进行交联,通过浸没沉淀法制备了交联EVAL膜,研究了不同TEOS添加量对膜的热性能、断面形貌、机械强度及油水分离性能的影响。结果表明:随着TEOS添加量的增加,EVAL膜的玻璃化转变温度上升,熔点和结晶度下降。膜内的交联结构使膜的机械强度得到明显改善,当TEOS添加量为0.87%时,交联EVAL膜的拉伸强度和断裂伸长率分别为纯EVAL膜的4.4倍和3.1倍。随着TEOS添加量的增加,膜的水通量先减小后增加,而截留率则呈相反的变化趋势;提高油相浓度,交联EVAL膜的截留率可达99.15%,表明该膜适用于较高浓度下的油水分离过程。     

PVP对PASS分离膜结构与性能的影响

作为膜材料,聚芳硫醚砜(PASS)具有耐高温耐溶剂等优点,但亲水性不强限制其应用。通过添加亲水性聚合物聚乙烯吡咯烷酮(PVP)改善其亲水性,并采用光学接触角测量仪、扫描电子显微镜(SEM)、超滤杯、紫外分光光度计等表征不同PVP含量时分离膜的接触角、形貌、水通量及截留率等。结果表明,PVP可明显改善其亲水性和水通量,截留率影响不大,也在一定程度上改变分离膜的结构形貌;PVP含量为15%时分离膜综合性能最好。     

多壁碳纳米管(MWNT)/聚丙烯腈(PAN)共混复合膜的制备及性能研究

为了提高PAN膜的性能,首先用超声分散将MWNT溶解在N,N-二甲基甲酰胺(DMF)中,之后加入PAN,通过相转化法制备MWNT/PAN共混复合膜.研究表明,随着MWNT添加量的增加,共混膜的拉伸强度呈先增加后减少的趋势,从2.2 MPa上升到2.4MPa后拉伸强度开始下降.这是由于适量的MWNT起到物理交联的作用,而添加过多,导致MWNT团聚,降低共混膜的拉伸强度.断裂伸长率随着添加量的增加缓慢下降,从20%下降到18.6%;水通量随着MWNT添加量的增加呈先增加后减少的趋势,在添加量为质量分数1%时较纯PAN膜增加了近60%,后水通量呈下降趋势,但是仍然高于PAN膜.这一变化趋势是由膜孔结构的变化和MWNT堵孔共同作用的结果.共混膜的截留率也呈先增加后减少的趋势.当MWNT添加量为4%时,截留率达到最大值96%.抗污染性能测试结果显示膜的水通量恢复率随着添加量的增加呈先增后减少的趋势,在添加量为7%时,达到70%.抗污染性能提高的原因是膜的润湿性得到改善.     

纳米纤维素晶/醋酸纤维素共混超滤膜材料的研究

采用浸没沉淀相转化法制备了纳米纤维素晶(CNC)/醋酸纤维素(CA)完全环境友好的共混膜材料,考察了在铸膜液中添加不同质量分数的CNC对共混膜各方面性能的影响。通过超滤装置测定了共混膜的水通量、截留率、含水率和孔隙率;通过万能试验机、环境扫描电子显微镜(SEM)、热重分析仪(TGA)对超滤膜进行了力学性能、形貌结构和热稳定分析。结果表明,随着CNC含量增加,共混膜的孔隙率呈增长趋势,由40.8%提高到66.4%,大孔由原来的规则圆形漏斗状变为狭长椭圆状且互相连通,水通量和拉伸强度呈先上升后减小的趋势。当CNC添加量为0.5%时,共混膜综合性能最优,相比纯CA膜,水通量提高64.7%,拉伸强度提高70%,热稳定性也得到增强。     

聚丙烯酸/多壁碳纳米管/聚偏氟乙烯共混膜的制备与表征

为了提高膜的亲水性和分离性能,以聚偏氟乙烯(PVDF)为聚合物,多壁碳纳米管(MWCNTS)和聚丙烯酸(PAA)为添加剂;聚乙烯吡络烷酮(PVP)为致孔剂; N,N-二甲基乙酰胺(DMAC)为溶剂,通过共混和相转换法(NIPS)制备了PAA/MWCNTS/PVDF膜(PMPM)。使用傅里叶红外光谱和扫描电镜表征膜的形貌特征,通过水通量、截留率等测试考察了膜的亲水性和分离性能。结果表明:MWCNTS和PAA的协同作用确实有利于膜的亲水性和分离性能改善,并且当MWCNTS含量为0. 5%,PAA含量为0. 6%时,膜的综合性能达到最优,与纯膜相比,纯水通量和截留率分别提升了89. 04%和13. 5%。     

GO/膨润土/PVDF复合膜的制备及性能研究

为了提高聚偏氟乙烯(PVDF)膜的疏水性和抗生物污染性能,以氧化石墨烯(GO)和膨润土为改性材料制备PVDF复合膜,并对其进行膜通量、截留率、拉伸强度、亲水性、孔隙率及抗生物污染性能研究。结果表明,当GO添加量为0.6%,复合膜的各项性能达到最佳;添加膨润土可以提高复合膜亲水性、拉伸强度、膜通量和截留率,但会导致孔隙率有所下降。此外,还以铜绿假单胞菌为研究对象,研究了复合膜的抗生物污染和抑菌性能,结果表明,复合膜的生物污染过程明显降低,且细菌生长缓慢,说明复合膜具有减缓生物污染的作用,具有一定的抑菌性。     

聚乙烯吡咯烷酮含量对聚偏氟乙烯/聚醚砜共混膜性能和结构的影响

采用二甲基乙酰胺为溶剂,聚乙烯吡咯烷酮(PVP K90)为致孔性添加荆,研究了PVP的浓度对聚偏氟乙烯/聚醚砜(PVDF/PES)共混膜的收缩率、纯水通量、牛血清蛋白(BSA)截留率和膜结构的影响.在PVP含量为5%时,共混膜的收缩率最低,水通量取得极大值,截留率有一极小值.     

固定化溶菌酶的氧化石墨烯/聚醚砜杂化超滤膜制备及抗菌性能研究

以氧化石墨烯(GO)为固定酶载体,在水溶液中通过静电吸附及氢键作用实现溶菌酶(Ly)的固定化得到GO-Ly。并将已固定化酶的GO为添加剂,以聚醚砜为膜材料,采用相转化法制备杂化超滤膜。考察了添加剂含量对膜形态、亲水性、分离性能、力学性能及抗菌性能的影响。结果表明,GO-Ly的加入使杂化膜的亲水性及纯水通量得到明显提高,同时拉伸强度也得到一定改善;尤其当GO-Ly添加量为1.5%(质量分数)时,膜的纯水通量达到318 L/(m2.h),并且对聚乙烯醇(PVA 30 000～70 000)的截留率维持在99%以上,对大肠杆菌的抑菌率可达68%。     

N,N-二甲基乙酰胺/氯化锂体系下醋酸纤维素/聚醚砜共混膜的制备与表征

为提高纯聚醚砜(PES)膜的亲水性和抗污染能力,以N,N-二甲基乙酰胺/氯化锂(DMAc/LiCl)体系为溶剂,以聚乙烯吡咯烷酮(PVP K30)为添加剂,采用相转化法制备醋酸纤维素(CA)/聚醚砜(PES)共混膜.探讨和分析了成膜过程中的各种因素对膜纯水通量和BSA(牛血清蛋白)截留性能的影响.确定CA/PES共混膜的最佳铸膜条件为:聚醚砜质量分数18%,PVP K30的质量分数4%,醋酸纤维素质量分数3%,预蒸发时间为20s.对共混膜进行了SEM形貌结构、热稳定性、接触角测试、BSA抗污染性能和共混相容性分析表征.结果表明,DMAc/LiCl体系下制备的CA/PES共混膜亲水性和BSA抗污染性能高于纯PES膜,CA/PES共混体系为部分相容体系,CA/PES共混膜的高温热稳定性稍有下降.     

半互穿网络法亲水改性超滤膜

以聚砜(PSF)为膜材料,水为凝胶剂,采用浸没沉淀相转化法制备PSF超滤膜,在制膜过程中添加了亲水性聚合物聚乙烯基吡咯烷酮(PVP)和络合剂FeCl2来改性PSF膜的亲水性,并对其性能进行表征.用红外来表征其络合性能,用接触角测量仪测定其亲水性能.探讨了PSF浓度,络合剂FeCl2用量,PVP用量,PVP分子量对超滤膜性能的影响.结果表明,增加PSF浓度,膜的通量变小;增加络合剂FeCl2的用量,膜的通量由大变小,是没有加络合剂的1.3倍;增加PVP的浓度,膜的亲水性得到了显著的提高.在4%的时候为最大,此时的通量比没加PVP的膜大11倍.而对于不同牌号的PVP,K60的通量最大,K90的最小.对牛血清蛋白(BSA)的截留率都达到了95%以上.     

Sorption, diffusion, and pervaporation characteristics of dimethylformamide/water mixtures using sodium alginate/polyvinyl pyrrolidone blend membranes

Separation of aqueous dimethylformamide (DMF) solutions in the concentration range of 0-100 wt% were studied using sodium alginate (NaAlg)/polyvinyl pyrrolidone (PVP) blend membranes. The NaAlg was blended in different ratios with PVP. Prepared membranes were crosslinked with CaCl₂ for testing in pervaporation (PV) separation of DMF/water mixtures. Effects of feed composition (0-100 wt%), operating temperature (30-50 °C), and membrane thickness were investigated. Best results were obtained at the conditions of 75/25 NaAlg/PVP blend ratio (w/w), 40 °C temperature, 20 wt% DMF concentration, and 70 μm membrane thickness. Blending of PVP with NaAlg increased permeation flux whereas it decreased the separation factor. NaAlg/PVP membranes gave separation factors of 5.5-27 for permeation flux of 0.96-1.81 kg/m²h depending on the operating temperature and the feed mixture composition. Arrhenius plot of permeation flux data versus reciprocal of temperature exhibited linear trends. Permeation activation energy of DMF and water in the PV was calculated as 6.76 and 1.88 kcal/mol, respectively, using an Arrhenius type relationship. Sorption-diffusion properties of the NaAlg/PVP membranes were also investigated at the operating temperature and the feed composition.     

Toxic metal ion separation by cellulose acetate/sulfonated poly(ether imide) blend membranes: effect of polymer composition and additive

Toxic heavy metal ion removal from industrial effluents are gaining increased visibility owing to environmental concern and saving precious materials. In this work, an attempt has been made to remove the valuable metal ions using modified ultrafiltration (UF) blend membranes based on cellulose acetate (CA) and sulfonated poly(ether imide) (SPEI) were prepared in the presence and absence of additive, poly(ethylene glycol) 600 (PEG600) in various compositions. Prepared membranes were characterized in terms of pure water flux (PWF), water content and membrane hydraulic resistance. High flux UF membranes were obtained in the range of 15-25 wt% SPEI and 2.5-10 wt% PEG600 in the polymer blend. The molecular weight cut-off (MWCO) of the blend membranes were determined using protein separation studies found to vary from 20 to greater than 69 kDa. Surface morphology of the blend membranes were analysed with scanning electron microscopy. Studies were carried out to find the rejection and permeate flux of metal ions such as Cu(II), Ni(II), Zn(II) and Cd(II) using polyethyleneimine as the chelating ligand. On increasing the composition of SPEI and PEG600, the rejection of metal ions is decreasing while the permeate flux has an increasing trend. These effects are due to the increased pore formation in the CA/SPEI blend membranes because of the hydrophilic SPEI and polymeric additive PEG600. In general, it was found that CA/SPEI blend membranes displayed higher permeate flux and lower rejection compared to pure CA membranes. The extent of separation of metal ions depends on the affinity of metal ions to polyethyleneimine to form macromolecular complexes and the stability of the formed complexes.     

Effect of PVP loading on pervaporation performance of poly(vinyl alcohol) membranes for THF/water mixtures

This work reports an experimental study on the pervaporative dehydration of an industrial solvent tetrahydrofuran (THF) using a blend membrane of PVA/PVP crosslinked with maleic acid. The influence of feed composition and permeate pressure on the pervaporation flux and selectivity has been investigated. The membrane was found to exhibit a water flux of 0.007 kg/m² h with a water selectivity of infinity for dehydration of 97% THF at 30 °C. FTIR of the blend was carried out to interpret its behavior on the basis of interactions between carbonyl groups of the cationic PVP and hydroxyl groups of the neutral PVA polymer. X-ray diffraction and sorption studies were carried out to study the degree of crystallinity and polymer–liquid interactions. The variation in film morphology was examined by scanning electron microscopy (SEM). Pervaporation experiments showed that high selectivity and promising permeability were obtained with a 9:1 blending ratio of PVA/PVP membrane crosslinked with 5 wt% maleic acid.     

PLLA/PVP共混静电纺丝形貌表征及性能研究

采用静电纺丝法制备了PLLA/PVP共混纤维膜,通过SEM、接触角表征了纤维膜的形貌以及亲水性能,同时测定了纤维膜的力学性能,探讨了共混液中PVP的比例对纤维膜形貌、亲水性能及力学性能的影响。结果表明:随着共混液中PVP比例的增大,PLLA的亲水性得到改善,但纤维的强力却迅速下降。当PVP的比例为40%和50%时,接触角接近零。SEM分析结果显示:纤维丝上孔的孔径和密度随着PVP比例的增大而发生改变。     

凝固浴组分对双凝固浴法制备PVDF膜结构和性能的影响

在内外凝胶浴中添加不同含量的溶剂,采用双凝固浴法制备了PVDF/PVP/DMAc中空纤维膜.通过膜形貌扫描电镜( SEM)表征,纯水水通量和牛血清蛋白(BSA)截留率测试实验,分析评价了凝固浴中溶剂含量对PVDF中空纤维膜结构与性能的影响.结果表明,凝固浴中溶剂含量增大会导致皮层孔隙率增多,而对亚层结构的影响各不相同.膜的纯水渗透通量变化无明显规律性,但BSA截留率保持相对稳定.当内外凝固浴中溶剂体积分数分别为30％和70％时,膜内部大孔发育良好,亚层疏松多孔,水通量分别为270 L/(m2,h)和548 L/(m2·h),显示了良好的渗透性能.     

氧化石墨烯/笼型聚倍半硅氧烷星型嵌段共聚物复合质子交换膜的制备与性能

通过共混的方法制备了含笼型聚倍半硅氧烷(POSS)星型拓扑结构嵌段共聚物的氧化石墨烯(GO)/笼型聚倍半硅氧烷-(聚甲基丙烯酸甲酯-共聚-磺化聚苯乙烯)(POSS-(PMMA₂₆-b-SPS₁₅₆)₈)复合质子交换膜。通过研究复合质子交换膜的离子交换容量(IEC)、质子传导率、吸水率与溶胀率,考察了GO含量对复合质子交换膜性能的影响。研究发现:复合质子交换膜的离子交换容量随GO含量的增加而升高,吸水率和溶胀率随着GO加入而降低,在测定温度范围内复合质子交换膜均表现出较高的尺寸稳定性,GO的添加改善了纯聚合物膜在80℃失水导致传导率下降的问题,提高了质子交换膜的质子传导率,发现在相对湿度为100%、80℃时,GO含量为0.3wt%的复合质子交换膜的质子传导率约为纯聚合物膜的3.2倍。      

聚砜/聚醚类高聚物共混相容性及超滤膜的研究

研究了由聚砜(PSf)和自制的聚醚类高聚物制备的共混超滤膜的组分相容性、性能及膜结构．利用差示扫描量热仪(DSC)测定了纯PSf、纯聚醚类高聚物以及不同PSf／聚醚类高聚物共混配比制得的超滤膜的玻璃化转变温度(Tg)．实验结果表明,PSf与聚醚类高聚物组分在整个配比范围内完全相容．所测定的共混膜的Tg与利用Fox方程得出的理论计算值相一致．PSf／聚醚类高聚物共混膜的水通量要高于纯PSf和纯聚醚类高聚物且截留率几乎没有变化．通过扫描电子显微镜(SEM)观察了膜的形态并对膜的超滤性能进行了解释．     

DMAc / LiCl 体系下纤维素 / 聚醚砜共混膜的制备与表征

采用 N,N-二甲基乙酰胺(DMAc) / 氯化锂(LiCl)体系作为纤维素溶剂,制备了纤维素 / 聚醚砜共混膜。探讨了共混比对膜的断裂强度、断裂伸长率和纯水通量等膜性能的影响,并确定了纤维素 / 聚醚砜最佳共混比为 1 : 16。 对共混膜进行了 SEM 和 DSC 分析,确认了纤维素 / 聚醚砜共混膜是一个相容的聚合物共混体系。