烧结温度对TiO_2/不锈钢中空纤维复合膜结构和性能的影响

不锈钢中空纤维膜基膜孔径大,直接涂覆分离层容易产生表面缺陷。在二氧化钛悬浮液中加入聚乙烯醇作为黏结剂,通过真空辅助抽滤法在不锈钢中空纤维基膜表面形成一层均匀的分离层。通过高温烧结得到了TiO_2/不锈钢中空纤维复合膜,考察了烧结温度对于TiO_2/不锈钢中空纤维复合膜表面分离层形貌和结构的影响。不同烧结温度时,TiO_2/不锈钢中空纤维复合膜的表面形貌有所差异;随着烧结温度的升高,不锈钢复合膜的孔径和纯水通量均先升高再下降。当烧结温度为500℃时,表面涂层均匀,孔径分布集中,水通量较高。最后,以SPT-500膜测试了水包油乳液分离效果,分离效率达到99%以上,且具有良好的抗污染性能。     

烧结温度对不锈钢纤维烧结毡拉伸性能的影响

以316 L、6μm不锈钢纤维为研究对象,研究了烧结温度对不锈钢纤维烧结毡拉伸性能的影响。通过SEM对不同温度制备的不锈钢纤维烧结毡的微观结构进行表征。结果表明,烧结温度低于1 200℃时,纤维之间搭接点烧结不牢固,导致纤维毡拉伸性能降低;烧结温度高于1 200℃时,纤维中晶粒容易长大,纤维表面易出现竹节状结晶,导致纤维毡拉伸性能降低;烧结温度在1 200℃时,制备出抗拉强度达31 MPa和延伸率约为10%的不锈钢纤维毡。因此,保证形成高强度烧结结点同时避免形成粗大竹节状晶粒是制备高强度、高韧性不锈钢纤维烧结毡的关键。     

中空纤维气体膜分离器丝外流速分布及其对分离性能的影响

实验测定了φ103×1300 mm中空纤维气体膜分离器丝外的流速分布.结果表明,分离器中丝外气体流速分布不均匀.而且,随着气体处理量的降低,流速不均匀程度增大,器内中心处流速最大,近壁处流速最小.假定器内流动是轴对称的,导出了流速不均匀情况下,流量分布和流道分布的数学模型,并且计算了对分离性能的影响.模拟计算结果表明,对N_2/H_2膜分离器而言,器内流动不均匀性对分离结果有明显影响.     

PVDF/编织管中空纤维复合膜的制备及其性能研究

以纤维编织管为支撑层,通过涂覆-浸没沉淀相转化技术,制备了超高强度、大通量的PVDF/编织管中空纤维复合膜,考察了铸膜液中PVDF和添加剂PVP含量等对膜性能的影响。结果显示,随铸膜液中PVDF含量增加,复合膜纯水通量下降,爆破强度增加,平均孔径减小;PVP的质量分数从2%增加至10%,膜通量呈现降低趋势,但爆破压力先增后减;当PVDF、PVP的质量分数分别为8%、6%时,复合膜纯水通量达4 300 L/(m2·h),爆破压力为0.32 MPa。研究范围内,复合膜孔隙率始终保持在45%以上,爆破压力高于0.30 MPa,且由于编织管的存在,而使复合膜的拉伸强度很高,显示了较好的过滤性能;添加PVP和PVA较PEG在膜性能方面的贡献更突出。     

水蒸气在中空纤维复合膜中渗透的微分阻力模型

建立了水蒸气在中空纤维复合膜中渗透的微分阻力模型,用实验验证了模型的可靠性。采用该模型估算出中空纤维膜的结构参数,研究了水蒸气在各层膜中的阻力,并以H2O/C2H2系统为例,考察了膜的结构参数对H2O/C2H2选择性的影响。     

制备条件对聚酰亚胺中空纤维膜性能影响的研究进展

综述了内部和外部凝固剂的化学性质、凝固浴温度等对聚酰亚胺（PI）中空纤维的形态和对PI中空纤维膜的气体分离,性能的影响。同时,叙述了纤维塑化抑制和亚胺化条件控制等对提高PI中空纤维膜分离性能的作用.     

PVDF-TiO2复合中空纤维膜的制备与表征

将纳米二氧化钛(TiO₂)粒子与4类制膜添加剂复配处理,采用相转化法制备聚偏氟乙烯(PVDF)-TiO₂复合中空纤维膜,讨论了纳米TiO₂粒子对复合膜结构和性能的影响。通过扫描电子显微镜、X射线衍射、能谱分析、热重分析、拉伸试验、接触角测定和超滤实验分别表征了复合膜的微观孔结构、晶相结构和复合均匀性、热稳定性、机械性能、亲水性、超滤性能以及抗污染性能。结果表明：通过添加TiO₂粒子复配添加剂,复合膜的性能得到有效改善。复配添加剂中w(TiO₂)为2%(占PVDF固含量的质量分数)时,纯水通量由348 L/(m²·h)提高至377 L/(m²·h),牛血清蛋白截留率由68%提高至90%,断裂强度和抗污染性能提高,复合膜综合性能优异。     

荷电中空纤维复合膜及其正渗透性能研究

以聚丙烯中空纤维微滤膜为底膜、羧甲基纤维素钠为功能材料、氯化铁为交联剂,采用溶液涂覆-交联工艺制备了表面荷电的中空纤维复合膜,将该中空纤维复合膜用于正渗透(FO)过程,研究了汲取液盐含量、原料液流速等对FO通量的影响。结果表明,制备的荷电中空纤维复合膜可用于FO过程,以蒸馏水为原料液、Na2SO4水溶液为汲取液,采用PRO模式进行FO试验,当原料液与汲取液体积流量均为15 mL/min、汲取液浓度为0.5 mol/L时,FO水通量为12.3 L/(m2.h),盐通量与水通量的比为1.42 g/L。     

全氟磺酸中空纤维膜的结构研究

本文用熔融纺丝的方法，纺制了全氟磺酸中空纤维膜。经化学处理后，用透射电镜和动态力学粘弹仪，对其结构进行了研究，并用称重法测试其对水的吸附行为，结果表明：透射电镜可以直接观察到Ａｇ＾＋染色后的Ｓｉｏｃｉｏｎ－Ｈ中的离子簇：由于离子簇的束缚，与Ｓｉｏｃｉｏｎ－Ｆ相比，Ｈ型和盐型Ｓｉｏｃｉｏｎ中空纤维膜的玻璃化转变温度和低温转变峰向高温方向推移；Ｓｉｏｃｉｏｎ－Ｈ中空纤维膜对水的吸附性能随交换容量的增加     

PVDF–TiO2 composite hollow fiber ultrafiltration membranes prepared by TiO2 sol–gel method and blending method

Organic–inorganic polyvinylidene fluoride (PVDF)–titanium dioxide (TiO₂) composite hollow fiber ultrafiltration (UF) membranes were prepared by TiO₂ sol–gel method and blending method, respectively. The membranes were characterized in terms of microstructure, hydrophilicity, permeation performance, thermal stability, and mechanical strength. The experimental results indicated that PVDF–TiO₂ composite UF membranes exhibited significant differences in surface properties and intrinsic properties because of the addition of inorganic particles. The TiO₂ particles improved the membrane strength and thermal stability of PVDF–TiO₂ composite UF membranes. In particular, hydrophilicity and permeability increased dramatically with the increase of TiO₂, whereas the retention property of UF membranes was nearly unchanged. However, high TiO₂ concentration induced the aggregation of particles, resulting in the decline of hydrophilicity and permeability. Compared with PVDF–TiO₂ composite hollow fiber UF membranes prepared by TiO₂ blending method, PVDF–TiO₂ composite hollow fiber UF membranes prepared by TiO₂ sol–gel method formed a dispersed inorganic network, and the stronger interaction between inorganic network and polymeric chains led to TiO₂ particles being uniformly dispersed in UF membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and membrane performance of poly(ethylene-co-vinyl alcohol) hollow fiber membrane via thermally induced phase separation

Poly(ethylene-co-vinyl alcohol) (EVOH) hollow fiber membranes with ultrafiltration performance were prepared from EVOH/glycerol systems via thermally induced phase separation (TIPS). The diluent glycerol was used as bore liquid to make a lumen of the hollow fiber for the purpose of prevention of the diluent evaporation and the larger pores formation at the inner surface of the hollow fiber. The obtained hollow fiber membranes showed asymmetric structures with skin layer near the outer surface, the larger pores just below the skin layer and the smaller pores near the inner surface. The formation of the larger pores near the outer surface was due to the enhanced pore growth by the water penetration. Some primary factors affecting the structure and performance of the membranes such as ethylene content (EC) in EVOH, cooling water bath temperature and take-up speed were studied extensively. The water permeability can be improved by increasing the water bath temperature and the take-up speed and by decreasing the EC. Both the pore size at the outer surface and the connectivity between the pores have to be considered together to understand the experimental result of the water permeability and the solute rejection.     

中空纤维渗透汽化复合膜及组件研究进展

中空纤维渗透汽化膜组件具有器件小型化及成本较低等方面的优势,其工业应用潜力巨大。本文介绍了中空纤维渗透汽化复合膜及组件的研究进展,阐述了膜材料、成膜方法以及组件结构参数等对组件渗透汽化性能的影响,并对中空纤维渗透汽化膜组件的中试研究进行了总结。通过组件放大及中试研究发现,中空纤维渗透汽化膜组件的装填密度、长度以及抽吸方式均会影响其下游侧的真空度,从而影响其渗透汽化性能。膜材料的分子设计、组件的结构参数优化以及耐溶剂耐高温封装将是中空纤维渗透汽化膜组件未来工业放大过程中的关键环节。     

A TiO2 modified whisker mullite hollow fiber ceramic membrane for high-efficiency oil/water emulsions separation

Design and preparation of membranes with ultrahigh separation performance and antifouling property for oil-in-water (O/W) emulsions remains challenging. In this study, a high flux mullite/TiO₂ ceramic composite membrane was prepared via multi-precipitation of TiO₂ on a whisker mullite hollow fiber support synthesized by combining phase inversion and high-temperature sintering techniques. The results showed that the generated whisker mullite structure improved the permeation flux, and the micro-nano structured TiO₂ functional layer endowed the membrane surface with superhydrophility and stability. The retention of the optimal composite membrane (M20T13) that was soaked in the titanium solution 20 times for 13 min each time for the O/W emulsions like n-hexane, toluene and engine oil maintained over 98 %, and the flux after 6 h filtration was 668.34 L·m⁻²·h⁻¹, 487.25 L·m⁻²·h⁻¹ and 258.66 L·m⁻²·h⁻¹, respectively, much higher than that of the optimal substrate (F3A1, mass ratio of fly ash: Al₂O₃ = 3:1). Moreover, the flux recovery rate of M20T13 was much higher than that of F3A1 after chemical backwashing. This work manifests great potential in O/W treatment fields.     

Fabrication of highly permeable PDMS@ZIF-8/PVDF hollow fiber composite membrane in module for ethanol-water separation

The construction of high-performance MOF-based hollow fiber composite membrane (HFCM) modules is a significant, yet challenging task for the biofuel production industry. In this study, a novel approach was taken to fabricate PDMS@ZIF-8/PVDF HFCMs in modules through a facile ZIF-8 self-crystallization synthesis followed by pressure-assisted PDMS infusion for pervaporation ethanol-water separation. The as-prepared HFCMs exhibited an ultrathin separation layer (thickness, 370 ± 35 nm), which was achieved through precise regulation of the ZIF-8 membrane and defect repair by PDMS infusion. Moreover, the strategy utilized in this study resolved the defect issues arising from MOF agglomeration in conventional composite membranes. Impressively, at the optimal packing density, the prepared membrane demonstrated a remarkable ethanol flux (1.11 kg m⁻² h⁻¹) with an PSI value (26.59 kg m⁻² h⁻¹) and showed promising long-term stability for the pervaporation of 5 wt% ethanol aqueous solution at 40°C.     

介孔Al_2O_3/PVDF复合中空纤维膜的制备及其性能

为了提高PVDF中空纤维膜在处理含油废水过程中的亲水性能、抗压实性能和抗污染性能,实验以介孔Al2O3为无机添加粒子,采用溶液纺丝法制备出介孔Al2O3/PVDF复合中空纤维膜。通过扫描电子显微镜和傅里叶红外光谱观察介孔Al2O3/PVDF复合中空纤维膜的形貌和成分,结果证明介孔Al2O3成功地添加到PVDF中空纤维膜中。通过接触角,纯水和含油废水通量的测试,结果表明介孔Al2O3的添加改善了PVDF膜的亲水性能、抗压实性能和抗污染性能。     

Effects of coating solvent and thermal treatment on transport and morphological characteristics of PDMS/Torlon composite hollow fiber membrane

A new approach for formation of the polydimethylsiloxane (PDMS) layer on Torlon polyamide‐imide hollow fiber (PAI‐HF) support has been developed by directly after fiber spinning without the need to undergo the final conventional solvent exchange and drying step, thereby saving postspinning processing steps. The produced PDMS/PAI‐HF composite membranes were found to have high CO₂ permeance (i.e., 1100 GPU) and exhibited good CO₂/N₂ selectivities of 8–10 which is close to 90% of that of a PDMS dense film. The effects of coating solution, rewetting and crosslinking temperature on the PAI‐HF morphological features, that is, gas transport, skin thickness, skin integrity, and substructure resistance are investigated. The rewetting and thermal treatment of the PAI‐HF caused the densification of the skin layer and reduced the pore sizes on the top layer. In addition, the potential use of the PAI‐HF support with polymers that are insoluble in hexane is also considered. Effects of water, methanol, and hexane exposure of PAI‐HF to these solvents are considered. This evaluation calls attention to issues that must be addressed in any eventual use of the PAI‐HF with water‐soluble or methanol‐soluble selective layer polymers, rather than simple hexane‐soluble polymers such as PDMS. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45418.     

Pervaporative separation of butanol using a composite PDMS/PEI hollow fiber membrane

In the study, the separation and purification of butanol was carried out using the composite hollow fiber membrane having the active layer of polydimethylsiloxane (PDMS) on the macroporous support of polyetherimide (PEI). The pervaporation results with the initial butanol concentration showed a trade-off between flux and separation factor. However, both the flux and the separation factor increased as the operating temperature increased. The pervaporation results showed the butanol flux and the separation factor were higher than those of the reported results. In this study, butanol was concentrated by the pervaporation as a feasibility study for the biofuel applications.     

PVDF-ZrO2复合中空纤维膜在乳化油废水中的应用

针对普通聚偏二氟乙烯(PVDF)中空纤维膜具有疏水性强、易污染的应用缺陷,在制备纳米粒子掺杂改性的PDVF-ZrO2复合中空纤维膜前期工作基础上,表征了其微观结构,并考察了其在油水体系中的分离效果。微观结构检测表明,随着ZrO2含量的增大,复合膜的断面微观结构完成由指状大孔向海绵状结构的转化。PDVF-ZrO2复合膜的接触角和牛血清蛋白(BSA)吸附实验结果显示其亲水性及抗污染性能均得到了提高。进一步考察了PDVF-ZrO2复合中空纤维渗透分离性能,ZrO2纳米粒子质量分数为0.3%时,显示了最佳的渗透性能。在乳化油废水处理过程中,在油质量浓度为1 g/L,操作压力为0.1MPa、搅拌强度为20 r/min条件下,通量为105 L/(m2.h),TOC去除率为95.4%,表明具有较好的废水处理效果。