添加剂对聚偏氟乙烯中空纤维超滤膜结构及性能的影响

在聚偏氟乙烯(PVDF)铸膜液中添加聚乙烯砒咯烷酮(PVP)、LiCl和苯乙烯-马来酸酐共聚物(SMA),采用相转化法制备了PVDF中空纤维共混超滤膜,并通过扫描电镜表征、膜通量和截留率测试等手段,研究了聚合物含量和不同添加剂对PVDF中空纤维膜的结构和性能的影响.结果显示,随着聚合物PVDF含量的增加,膜通量减小、截留率增加、拉伸强度增加;添加剂SMA对膜性能影响较大,PVP和LiC1含量对膜的结构及性能影响较小,随其含量的增加,膜截留率增加.     

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。     

PES/fMWNT共混超滤膜的制备及其抗污染研究

采用非溶剂致相分离法(NIPS)制备聚醚砜/羧基化碳纳米管共混膜,以N,N-二甲基乙酰胺(DMAc)和N-甲基吡咯烷酮(NMP)为溶剂,聚乙二醇(PEG4000)为致孔剂。研究了碳纳米管添加量和管径对膜结构和膜性能的影响。结果表明,共混膜的拉伸强度、杨氏模量随着碳纳米管含量的增加先增大后减小,但随着碳纳米管的管径增加而减小。当碳纳米管含量为1. 0%,管径为20～30 nm时,聚醚砜/碳纳米管共混膜的接触角从纯聚醚砜膜的78. 16°降到64. 30°,纯水通量达到50. 39 L/(m~2·h),是纯聚醚砜通量的4倍,对牛血清蛋白(BSA)截留率保持在95%以上,通量恢复率从54. 29%增加到84. 59%,抗污染性能较纯聚醚砜膜明显提高。     

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%。     

PVP含量对聚偏氟乙烯制备的编织管增强型中空纤维膜结构与性能的影响

以聚偏氟乙烯(PVDF)树脂为原料,选择聚乙烯吡咯烷酮(PVP)为成孔剂,N,N-二甲基乙酰胺(DMAC)为溶剂,制备PVDF编织管增强型中空纤维膜。研究了PVP的含量对制备膜丝的结构与性能的影响。结果表明,当PVP质量分数在10%时,所得膜丝的剥离强度和纯水通量性能最佳。     

PVB-PVDF共混膜的制备及其性能的研究

采用剪切粘度法对聚乙烯醇缩丁醛( PVB) -聚偏氟乙烯(PVDF)体系的相容性进行了定性研究,采用相转化法制备了PVB-PVDF共混膜,并对膜的结构和性能进行了测试.结果表明,该体系为部分相容体系;PVB-PVDF共混膜的纯水通量较PVDF膜、PVB膜均有很大程度的提高,PVB的加入改善了PVDF膜的亲水性及拉伸强度.聚合物的质量分数为23％、PVB与PVDF共混质量比为7:3的共混膜纯水通量和拉伸强度都较好,即综合性能最好.     

亲水性聚偏氟乙烯超滤膜的制备

采用干-湿相转化法研究了聚偏氟乙烯(PVDF)中空纤维超滤膜的制备。选用PVDF为膜材料,N,N-二甲基乙酰胺(DMAc)为溶剂,聚乙烯吡咯烷酮(PVP)和聚乙二醇(PEG)为添加剂,考察了一定条件下PVDF和PVP的百分含量及PEG的分子量对膜孔径、机械性能、水通量及形貌结构的影响,用正交实验设计确定了制膜的最佳配方为:PVP含量14%,PVDF含量18%,PEG分子量为200。此配方下所制备的中空纤维膜圆整度较好,断裂强力为3.2 N,断裂伸长率为70%,泡点为0.43 MPa,平均孔径为0.081μm,纯水通量为178 L/(m~2·h)。     

PVDF树脂的物性对中空纤维膜性能的影响

采用了不同特性粘度的PVDF树脂,通过非溶剂致相分离法(NIPS)制备了相应的PVDF中空纤维膜。通过力学性能、纯水通量、牛血清白蛋白(BSA)截留率等性能测试发现,不同特性粘度的PVDF树脂制备的中空纤维膜的性能差异较大。随着PVDF特性粘度的增加,PVDF中空纤维膜的拉伸强度及断裂伸长率逐渐增加,纯水通量逐渐降低,BSA截留率先降低后增加。通过扫描电镜(SEM)进一步发现,随着PVDF特性粘度的增加,PVDF树脂制备的中空纤维膜,其海绵层上的孔状结构逐渐减少且变小。     

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。     

复合PVDF膜材料性能及其MBR处理城市污水的研究

研究了1种异质编织管增强型复合聚偏氟乙烯(PVDF)膜材料的主要性能及其MBR处理低碳氮比城市污水的表现,并与传统PVDF膜材料作了比较。结果表明,复合PVDF膜单根膜丝可承受最大拉力为87N、弹性模量为200 MPa,复合PVDF膜组件纯水通量(在20 kPa下)和临界通量分别为85 L/(m2·h)和49~60 L/(m2·h),均明显高于传统PVDF膜。因此复合PVDF膜能承受高曝气量的冲刷并在高通量条件下运行。在处理低碳氮比城市污水时,复合PVDF膜MBR与传统PVDF膜MBR的出水水质相当。运行期间,复合PVDF膜和传统PVDF膜TMP增长率分别为0.65和0.73kPa/d,表明复合PVDF膜抗污染性能优于传统PVDF膜。     

碳纳米管悬浮液强化小型重力型热管换热特性

对水基多壁碳纳米管悬浮液强化小型重力型热管换热特性进行了实验研究。碳纳米管悬浮液质量分数为0. 1%～3%,热管运行压力为7. 45、12. 38和19. 97 kPa。实验结果发现,用质量分数为2. 0%的碳纳米管悬浮液替代去离子水后,热管蒸发段换热性能大幅度提高,临界热通量最大提高了120%。热管运行压力对蒸发段沸腾传热系数有明显影响,压力越小,碳纳米管悬浮液对沸腾换热特性的强化作用越显著。壁面热通量对蒸发段沸腾换热特性也有明显影响,低热通量时碳纳米管悬浮液的强化换热作用不明显,到高热通量时,其强化换热作用显著。     

Fabrication of polysulfone nanocomposite membranes with silver‐doped carbon nanotubes and their antifouling performance

In this study, polysulfone (PSf)/silver‐doped carbon nanotube (Ag‐CNT) nanocomposite membranes were prepared by a phase‐inversion technique; they were characterized and evaluated for fouling‐resistant applications with bovine serum albumin (BSA) solutions. Carbon nanotubes were doped with silver nanoparticles via a wet‐impregnation technique. The prepared Ag‐CNT nanotubes were characterized with scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The fabricated flat‐sheet PSf/Ag‐CNT nanocomposite membranes with different Ag‐CNT loadings were examined for their surface morphology, roughness, hydrophilicity, and mechanical strength with SEM, atomic force microscopy, contact angle measurement, and tensile testing, respectively. The prepared composite membranes displayed a greater rejection of BSA solution (≥90%) and water flux stability during membrane compaction with a 10% reduction in water flux values (up to 0.4% Ag‐CNTs) than the pristine PSf membrane. The PSf nanocomposite membrane with a 0.2% Ag‐CNT loading possessed the highest flux recovery of about 80% and the lowest total membrane resistance of 56% with a reduced irreversible fouling resistance of 21%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44688.     

外壁荷电性质对双壁碳纳米管中水分子运动行为的影响

采用分子动力学模拟方法考察了双壁碳纳米管外壁荷电性质对孔道内水分子运动行为的影响。模拟结果显示：外壁荷电的双壁碳纳米管中水分子链呈现“双偶极”分布,由此将水分子的偶极翻转限制在碳纳米管的中部,避免了整条水分子链的偶极翻转,加速了水分子运动。外壁负载电荷也增强了水分子与碳纳米管之间相互作用,降低了水分子进入碳纳米管的能量壁垒,增强了碳纳米管内水分子内的氢键稳定性,这些均有利于水分子加速进入碳纳米管并在其中连续运动。上述结果从分子水平上揭示了碳管中水分子流动机理,为设计新型水纯化膜材料提供了有益的启示。     

Enhancing water flux through semipermeable polybenzimidazole membranes by adding surfactant‐treated CNTs

In this study, surfactant‐treated carbon nanotubes (CNTs) were incorporated into polybenzimidazole (PBI) matrix to prepare the PBI/CNT composite membranes with CNT content in the range of 0 to 15 wt %. The composite membranes were fabricated by spin‐coating. The membrane morphology, mechanical property, and water and salt transport properties were investigated to characterize the additive effect of CNTs. The tensile strength of all the PBI/CNT composite membranes was lower than that of pristine PBI membrane, indicating the weak interaction between CNT and PBI. In addition, water flux increased without reducing the salt rejection when CNTs were homogeneously dispersed in the PBI matrix at a less than 7.5 wt % content. On the other hand, at 10 wt % and higher CNT content, submicro‐scaled cellular structure was formed, and both the water flux and salt rejection decreased. The well‐dispersed CNTs in the PBI matrix via weak interaction preferentially improve the water permeability by 1.7 times without depressing the salt rejection. The incorporation of well‐dispersed CNTs in polymer matrix provides a promising and facile option for improvement in the water transport properties through the polymeric semipermeable membranes with intrinsically low water permeability such as PBI. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45875.     

功能化碳纳米管/聚合物复合分离膜

碳纳米管不仅具有优异的力学性质和超大的比表面积,同时具有优良的传输特性,将其添加到聚合物中制备复合分离膜,具有广阔的应用前景。通过化学改性将碳纳米管功能化,提高其在聚合物中的分散性,制备碳纳米管/聚合物复合膜。本文在介绍了碳纳米管功能化、碳纳米管/聚合物复合膜制备方法的基础上,综述了功能化碳纳米管的加入对复合分离膜亲水性、水通量、机械稳定性以及分离等性能的影响。总结了近年来对碳纳米管在聚合物膜内定向排列的研究进展及碳纳米管定向对复合膜相关性能的影响。由于碳纳米管材料的各向异性,利用电场、磁场及流场等对碳纳米管在聚合物膜内的分布进行定向,从而充分利用其优异的性能,是该类复合膜的研究方向。     

Investigation on the enhancement of solvent-resistant nanofiltration membrane performance utilizing PDA-UiO-66@CNT as an interlayer

With the growing complexity of separation systems, the application of thin film composite nanofiltration (TFN) membranes in organic solvent separation faces numerous challenges. To augment its solvent stability, an in-situ constructed dopamine hydrogel doped with UiO-66@CNT was developed as an intermediate layer on a polyetherimide (PEI) ultrafiltration membrane. Subsequent interfacial polymerization on this interlayer led to the formation of a solvent-resistant nanofiltration membrane with a vast covalent bond structure, large specific surface area, and enhanced hydrophilicity. Our findings revealed that when the CNT loading in the UiO-66@CNT composite nanoparticles was 2 wt%, the TFN-U₂C₂ membrane exhibited a maximum pure water flux of 126.32 L/(m²·h) and a methanol flux of 45.45 L/(m²·h). The rejection rates for Congo red aqueous and methanol solutions were 96.88% and 92.14%, respectively. The membrane also demonstrated commendable anti-fouling properties. Remarkably, even after 48 h of immersion in various organic solvents, the membrane retained its morphology and separation efficiency. Compared to the TFN-U₂ membrane without CNT addition, the enhancement in separation performance was considerably significant. Hence, this membrane has significant potential for application in treatment of wastewater containing organic solvents and is promising in related fields.     

Ethanol purification using polyamide‐carbon nanotube composite membranes

This work presents synthesis and characterization of polyamide‐carbon nanotube (CNT) composite membranes for purification of ethanol. The solution‐casting method was applied for preparation of nanocomposite membranes. The nanocomposite membranes were characterized using scanning electron microscopy to ensure the fine dispersion of nanoparticles in polymer matrix. The effect of CNT loading on membrane performance was investigated. The separation performance of synthesized membranes was evaluated in separation of ethanol from ethanol/water mixture using pervaporation. Effect of feed temperature and feed concentration on separation of ethanol was investigated. The results showed that increasing temperature increases flux of ethanol through the membrane, but decreases separation factor. The results also confirmed that the best separation performance can be obtained at CNT loading of 0.5 wt%. Furthermore, a mathematical model was developed to simulate the separation process. The model was based on solving the continuity equation for ethanol in the feed side and membrane. The simulation results were compared with the experimental data and were in good agreement. POLYM. ENG. SCI., 54:961–968, 2014. © 2013 Society of Plastics Engineers     

Carbon nanotube supported platinum catalysts for the ozonation of oxalic acid in aqueous solutions

Ozonation of oxalic acid in the presence of carbon nanotube (CNT) supported platinum (Pt/CNT) catalyst in aqueous solution was studied. The activity and stability of Pt/CNT, the influence of preparation conditions on Pt/CNT activity and the ozonation mechanism of oxalic acid with Pt/CNT were investigated. It was found that Pt/CNT was more active for oxalic acid removal and more resistant to ozonation compared with the case of activated carbon supported Pt catalyst. The Pt loading, reduction temperature and pyrolysis atmosphere significantly influenced the Pt/CNT activity, especially for pyrolysis atmosphere. By means of X-ray diffraction and X-ray photoelectron spectroscopy analysis, the aggregation of Pt and the existence of chemisorbed oxygen with Pt were found when the Pt/CNT catalyst was prepared by calcination, which are unfavorable for its performance. The CNT was oxidized and some acidic groups were generated in calcination, which also cause a decrease of Pt/CNT activity. A free radical mechanism was proposed which involves ozone decomposition and hydrogen peroxide formation for oxalic acid degradation on Pt/CNT. The redox couple of Pt_red/Pt_ox was suggested to be crucial for the improvement of CNT activity. The Pt/CNT has a good stability after five re-uses without any leaching of Pt.     

碳纳米管荧光特性的研究进展

近年来,对碳纳米管光学性质的研究引起了人们广泛的关注,特别是碳纳米管在近红外波段的荧光性质对于其在生物医学领域的应用具有深远的意义。结合现有的研究特点,对碳纳米管的荧光特性及其应用方面的研究现状进行了综述,并对该领域的发展趋势进行了展望。     

改性碳纳米管及其复合材料在废水处理中的应用现状及展望

碳纳米管（carbon nanotube, CNT）具有高比表面积、高吸附能力、优良的导电性和化学稳定性等,但其在水中存在分散性差和催化能力低等问题。为了提高其在废水处理中性能,需要对CNT进行改性,制备复合材料。本文总结了CNT表面改性和复合材料制备方法,论述了改性CNT及其复合材料在电化学氧化、电化学还原、电化学过滤、光催化和膜分离等处理技术中的应用研究进展,并就未来研究方向进行了展望。指出了CNT在未来废水处理方面应用的研究重点包括：①设计经济、方便、温和的改性路线,继续寻求获得新型高效改性CNT及其复合材料,并兼顾稳定性;②开发基于改性CNT及其复合材料特性的废水处理新装置和反应工艺;③关注因改性CNT及其复合材料流失引起的生物、生态效应。