聚氨基葡糖超滤膜的研制及其在印染废水处理中的应用

简要叙述了聚氨基葡糖超滤膜的制备方法。着重研究了其在印染废水处理中的应用,结果表明用聚氨基葡糖超滤膜实际印染废水,其ＣＯＤ去除率可达８０％左右,脱色率超过９５％。     

凝固浴组成对SMA/CPVC共混超滤膜的结构与性能影响

通过非溶剂致相分离（NIPS）法制备了苯乙烯-马来酸酐共聚物（SMA）/氯化聚氯乙烯（CPVC）共混超滤膜,探讨了凝固浴中不同溶剂（DMAc）含量对其超滤膜表面酸酐基团偏析程度、微观结构、亲水性、水通量、截留率和抗污染的影响。结果表明：凝固浴中溶剂含量的增加抑制了酸酐基团向膜表面的偏析,导致亲水性减弱;同时,铸膜液中溶剂与水分子之间扩散速率的变小引起延迟分相,使得膜表面孔径变小和分布变窄。当溶剂质量分数为3%时,超滤膜对牛血清白蛋白（BSA）截留率提升至98.10%、通量恢复率为96.82%,且不可逆污染率降为3.77%,表明凝固浴中适量的溶剂可进一步提高超滤膜抗污染性能。     

凝胶相转化温度和空气预蒸发时间对PVDF超滤膜性能及结构的影响

利用非溶剂相转化法(NIPS),以聚偏氟乙烯(PVDF)/聚乙烯吡咯烷酮(PVP)/N,N-二甲基乙酰胺( DMAC)为铸膜液体系,水为凝固浴制备了大通量超滤膜.考察了铸膜液温度、凝胶浴温度、空气预蒸发时间等条件对超滤膜性能与结构的影响.研究结果显示,随着铸膜液和凝胶浴温度的提高,膜纯水通量增大,强度增强,截留率降低,膜的第一泡点压力减小,膜的孔隙率随铸膜液温度升高而增大,随凝胶浴温度升高先增大后减小,膜断面指状孔发育较为通透,海绵层致密.延长铸膜液在空气预蒸发时间,膜的第一泡点压力和孔隙率降低,超滤膜截留率提高,通量和强度变化不大.     

CA／PAN-Al2O3有机-无机复合超滤膜的制备

以醋酸纤维素(CA)及聚丙烯腈(PAN)为膜材料,以纳米三氧化二铝(Al2O3)为添加剂,通过浸入-沉淀相转化法制备了有机-无机超滤膜,从凝固浴温度及组成两个方面考察成膜规律.试验结果表明,凝固浴温度及组成对膜性能有较大影响,综合膜水通量及截留率多方面进行考虑,凝固浴温度50℃较为适宜;凝固浴中加入表面活性剂,膜的水通量及截留率均得到改善.     

聚砜管式超滤膜的制备及其结构性能研究

采用浸没相沉淀法制备聚砜(PSF)管式超滤膜。以纯水通量、卵清蛋白截留率、扫描电镜表征膜的结构和性能,考察了PSF含量、凝固浴温度和组成、添加剂种类和含量对PSF管式膜成膜性能及结构的影响。结果表明,凝固浴温度升高、聚乙烯吡咯烷酮(PVP)含量增加、PEG-400含量增加,都可以使膜的水通量增加、截留率降低;而凝固浴中添加溶剂二甲基乙酰胺(DMAc)、铸膜液中PSF含量的增加,都可以使膜的通量减小,截留率升高。     

PEO改性PVDF/SMA膜结构和性能

将聚氧化乙烯(PEO)添加到聚偏氟乙烯/苯乙烯马来酸酐树脂(PVDF/SMA)膜体系中,通过非溶剂致相分离法(NIPS)制备了添加不同PEO含量的PVDF/SMA共混膜。其中PEO质量分数为2%的共混超滤膜性能最好,水通量为531.1L/(m²·h),牛血清蛋白(BSA)截留率为65.8%,水接触角为63.6°,膜剥离强度为0.2756kN/m。接着以PVDF/SMA膜为主要研究对象测试了凝固浴温度对共混超滤膜的纯水通量以及BSA截留率的影响,该实验的结果表明凝固浴温度的改变对膜性能没有产生明显的影响。因此,选择在常温凝固浴温度下测试不同凝固浴成分对共混膜性能的影响。探究了膜在凝固浴成分分别为N,N-二甲基乙酰胺(DMAc)(质量分数为3%、6%、9%)、氯化钠(NaCl)(0.05mol/L、0.1mol/L、0.2mol/L)和乙醇(质量分数为3%、6%、9%)时的膜性能变化,以及对各个组分得到的膜样本进行扫描电子显微镜(SEM)表征。结果表明,随着DMAc含量增加,膜表面的孔在减少,且膜皮层的厚度增加,使得膜的水通量减少而BSA截留率提高。而随着NaCl浓度...     

凝固浴体系对PVDF超滤膜性能与结构的影响

利用非溶剂相转化法(NIPS),以聚偏氟乙烯(PVDF)、聚乙烯基吡咯烷酮(PVP)为铸膜液,水、二甲基乙酰胺(DMAC)、PVP体系为凝固浴,制备外压中空纤维超滤膜。研究了凝固浴中DMAC和PVP含量以及凝固浴温度对膜性能和结构的影响。结果表明,凝固浴中DMAC含量的增加可以提高超滤膜的通量、断裂伸长率和表面的孔径,降低膜丝拉力;PVP含量对膜通量、拉力与断裂伸长率有非线性影响,当着PVP的质量分数大于12%时,支撑层孔径明显增加;凝固浴温度升高可以增加膜的通量,而对孔隙率、拉力和断裂伸长率则影响不大。当凝固浴中DMAC和PVP的质量分数分别为35%和12%、凝固浴温度为70℃时,可以得到性能较好得超滤膜。     

高溶剂含量第1凝固浴停留时间对PVDF膜结构和性能的影响

以聚偏氟乙烯(PVDF)、聚乙烯吡咯烷酮(PVP)、二甲基乙酰胺(DMAc)为铸膜液体系,采用高含量溶剂DMAc水溶液作为第1凝固浴,水为第2凝固浴组成的双凝固浴制备PVDF中空纤维膜.通过扫描电镜(SEM)形貌观察,纯水水通量和BSA截留率测试,探讨了第1凝固浴停留时间对PVDF-PVP中空纤维膜性能与结构的影响.结果表明,随着膜丝在高溶剂含量第1凝固浴中停留时间从0变化至10s,膜丝纯水通量在2s时下降,之后持续增加,而BSA截留率不断降低.SEM显示随停留时间延长,膜表面孔隙率增加,亚层指状孔增多,大孔孔径增大,亚层海绵结构变得疏松.在停留时间为10s时,膜水通量达315 L·m-2.h-1,BSA截留率86％,可做为制备高通量PVDF超滤膜的最佳成形条件.     

低截留分子质量新型聚芳醚腈酮超滤膜的研制

以新型聚芳醚腈酮为膜材料 ,以N -甲基 - 2 -吡咯烷酮 (NMP)为溶剂 ,研究了聚合物浓度、添加剂种类及含量、凝胶浴温度等对超滤膜性能的影响。结果表明 ,聚合物质量分数以 1 2 %～ 1 3 %为合适的制膜浓度 ,以聚乙二醇PEG - 4 0 0为添加剂时获得了高截留率和高水通量的超滤膜。随着凝胶浴温度的升高 ,水通量明显增大 ,而截留率有所下降 ,而共聚物的浓度增加则有相反的效果。制得的超滤膜具有较低的截留分子量 (PEG- 2 0 0 0 ) ,将制得的超滤膜用于达旦黄、黄X-G等染料的分离 ,截留率均达 90 %以上     

1种聚偏氟乙烯中空纤维膜的制备方法等

解决了目前PVDF 中空纤维膜的永久亲水性差和机械强度差的问题,在改善亲水性和机械强度的同时保持中空纤维超滤膜的高通量和高截留率。主要实施方法为按照重量百分比组成,在反应釜中加入12%～28%聚偏氟乙烯,0.8%～6%表面活性剂,6%～30%成孔剂,38%～70%溶剂,0.1%～3%水,搅拌均匀,铸膜液过滤脱泡;铸膜液和芯液同时由纺丝喷头挤出,纺丝喷头温度为60～80℃,在确定的温度下保持温度变化幅度为±0.4℃;铸膜液在空气中以0.5～3 m/min的速度经过5～50 mm距离后进入外凝固浴中,在外凝固浴中停留时间为5～10 s,外凝固浴为30～60℃的水,在确定的温度下保持温度变化幅度为±0.2℃;得聚偏氟乙烯的中空纤维超滤膜。     

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。     

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     

High permeability poly(vinylidene fluoride) ultrafiltration membrane doped with polydopamine modified TiO2 nanoparticles

In order to improve the water permeability of poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membranes with low molecular weight cut-off (MWCO), polydopamine (PDA) was employed in the membrane preparation process. Owing to its merits of material-independent adhesion, PDA was coated on inorganic particles or added in coagulation bath to tailor the final membrane structure and property. The introduction of PDA broke through the permeability/selectivity trade-off of the PVDF membrane. By adding the PDA coated titanium dioxide (PDA/TiO₂) nanoparticles, water flux increased by 287% while MWCO kept similar with the pristine PVDF membrane. Thermodynamics and Kinetics of the PVDF/additives/non-solvent were analyzed and shown that nanoparticles reduced the thermodynamic stability and increased the phase separation speed, and the speed can be adjusted using different nanoparticles. Additionally, X-ray diffraction (XRD) test indicated that PVDF crystalline form changed from α phase to β phase after adding different nanoparticles. Permeability/selectivity trade-off was broken through by DA addition in coagulation bath. Compared with the original PVDF membrane, when the DA concentration of the coagulation bath was 2.0 g·L^-1, water flux increased by 312%, and MWCO of the PVDF membrane ranged in 10,000 to 20,000 Da as well as contact angle decreased from 81.4° to 45°.     

Effect of surfactant on morphology and pore size of polysulfone membrane

The skin layer structure can be changed by adjusting the diffusion rate of the non-solvent into the polymer solution between membrane and coagulation bath through adding surfactant into either coagulation bath or dope solution. When adding SDS in coagulation bath, the variation trend of apparent diffusion coefficient during phase separation and scanning electron microscopy morphology of resultant membranes indicated that, at the beginning SDS migrated to the membrane-bath interface during phase separation process, playing a role as mechanical barrier within 0.15 wt% SDS concentration. Once the SDS concentration exceeds CMC, the remaining SDS will form micelles act as a carrier, hence, the phase separation rate accelerated. The membranes were characterized roughness parameters, obtained by the atomic force microscopic technique. While adding surfactant in the dope solution, compared with SDS addition into the coagulation bath, apparent diffusion coefficient and SEM morphology showed the similar trend, and the excellent range of SDS concentration is 0.08 wt%-0.1 wt%. As changing the nature of surfactant in the dope solution, we found that, with the increase of surfactant hydrophile-lipophile balance (HLB) value, the rate of phase separation speeds up, the size of macrovoid increases, flux increases gradually and rejection is weakened.     

Preparation of PVDF ultrafiltration membranes using PVA as pore surface hydrophilic modification agent with improved antifouling performance

Novel polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes were facilely fabricated using polyvinyl alcohol (PVA) aqueous solution as the coagulation bath through phase inversion method. In the process, PVA was introduced into the pore surfaces of the PVDF membranes via the interdiffusion of the non‐solvent water and the solvent. The effects of PVA content in the coagulation bath on membrane properties were systematically discussed. The results indicated that the increase of PVA content in coagulation bath resulted in the formations of the more sponge‐like structures and the higher surface hydrophilicity. Smaller pore size led to lower water flux and higher bovine serum albumin rejection. Fouling resistance measurement indicated that the membranes made in PVA/water coagulation bath had higher flux recovery ratio (92.1%) than the membrane made in a pure water bath (71.0%). Furthermore, mechanical property test revealed that the resulting membranes had high tensile strength and Young's modulus. In this work, we found that the morphology and the property of the novel PVDF membranes could be determined by the PVA content in the coagulation bath. POLYM. ENG. SCI., 59:E384–E393, 2019. © 2018 Society of Plastics Engineers     

High permeability poly(vinylidene fluoride) ultrafiltration membrane doped with polydopamine modified TiO2 nanoparticles

In order to improve the water permeability of poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membranes with low molecular weight cut-off (MWCO), polydopamine (PDA) was employed in the membrane preparation process. Owing to its merits of material-independent adhesion, PDA was coated on inorganic particles or added in coagulation bath to tailor the final membrane structure and property. The introduction of PDA broke through the permeability/selectivity trade-off of the PVDF membrane. By adding the PDA coated titanium dioxide (PDA/TiO₂) nanoparticles, water flux increased by 287% while MWCO kept similar with the pristine PVDF membrane. Thermodynamics and Kinetics of the PVDF/additives/non-solvent were analyzed and shown that nanoparticles reduced the thermodynamic stability and increased the phase separation speed, and the speed can be adjusted using different nanoparticles. Additionally, X-ray diffraction (XRD) test indicated that PVDF crystalline form changed from α phase to β phase after adding different nanoparticles. Permeability/selectivity trade-off was broken through by DA addition in coagulation bath. Compared with the original PVDF membrane, when the DA concentration of the coagulation bath was 2.0 g·L⁻¹, water flux increased by 312%, and MWCO of the PVDF membrane ranged in 10,000 to 20,000 Da as well as contact angle decreased from 81.4° to 45°.     

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。     

Preparation of defect-free asymmetric membranes for gas separations

A technique was developed to prepare defect-free, asymmetric, polymer membranes for gas separation. The preparation method eliminates the need for coatings, which are usually required to render asymmetric, polymer based, membranes gas selective. In this method, a casting solution containing a polymer, solvent, and salt additive is given a desired shape and immersed in a coagulation bath containing a nonsolvent. The nonsolvent is selected to have a low affinity for both the solvent and salt additive. After the complete coagulation of the membrane, the additive salt is leached out in a second bath. This leads to the formation of an asymmetric membrane that has a well-interconnected porous network. The fine membrane structure is preserved by solvent exchange before it is finally dried. Polyetherimide (PEI) (Ultem® 1000) membranes were prepared from casting solutions containing 23, 25, and 26.5% (wt) PEI, various amounts of lithium nitrate and N-methyl-2-pyrrolidinone (NMP). Membrane performance was determined for the separation of oxygen from air. The effects of polymer concentration, additive salt concentration and the drying process on oxygen permeance, and the actual separation factor of the membrane are discussed. The addition of a small amount of solvent to the coagulation bath improved the leaching of the salt additive and produced membranes with a more open structure. A polymer concentration of 23% produced membranes with the highest performance. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1471–1482, 1999     

聚丙烯腈—聚氨酯共混超滤膜的研究

用聚丙烯腈和聚氨酯为膜材料,N,N-二甲基乙酰胺（DMAC）为溶剂,PEG 4000为添加剂制备超滤膜。研究了聚合物浓度、比例对膜结构和性能的影响。结果表明：随着聚合物浓度的增大,膜的水通量下降,截留率先升高后降低;当聚合物的比例为8∶2、质量分数为14%时,性能最佳。