基于MOFs的混合基质膜在渗透汽化中的研究进展

渗透汽化技术因节能、高效等优势被广泛应用于液体分离领域。金属有机骨架(MOFs)由于其高比表面积和高孔隙率、与聚合物相容性良好等特性而成为制备用于渗透汽化的混合基质膜最有前景的材料之一。简述了MOFs的概念和种类;总结了用于渗透汽化的混合基质膜对MOFs的选择标准,并综述了基于MOFs的混合基质膜在渗透汽化中的应用;最后提出基于MOFs的混合基质膜在工业放大方面存在的一些问题,同时展望了其未来在渗透汽化分离液体混合物方面的应用前景。     

PEBA/氮硫共掺杂多孔碳球混合基质膜的制备及CO2分离性能研究

为了获得高性能的混合基质膜,有效捕集烟道气中的CO₂,设计了对CO₂有优异的扩散选择性和吸附选择性的氮硫共掺杂多孔碳球添加剂,实现了烟道气中CO₂/N₂的高效分离。选用表面含氧基团丰富的葡萄糖作为碳源,硫脲作为氮源和硫源,通过水热法制备了氮硫共掺杂碳球（NSC）,并用KOH活化,获得了具有多孔结构的氮硫共掺杂碳球（NSPC）,再加入聚醚嵌段酰胺（PEBA）中制备出PEBA/NSPC混合基质膜。采用FTIR、XRD和BET表征了材料的化学结构和孔结构,借助力学性能表征了膜的两相界面相容性。系统研究了PEBA/NSPC混合基质膜中葡萄糖与硫脲的质量比、NSC和KOH的质量比、NSPC的添加量、操作压力、操作温度,以及模拟烟道气条件对膜CO₂渗透性、CO₂/N₂选择性的影响。结果表明：NSPC材料成功实现了氮、硫元素的共掺杂,而且具有较好的孔结构。在操作温度25℃、操作压力0.2 MPa的条件下,混合基质膜中NSPC添加量为3%（质量）时气体分离性能最优,CO₂渗透系数和CO₂/N₂选择性分别为589 Barrer和64,相比纯PEBA膜分别提高了244%和139%。这是因为多孔碳球的微孔结构显著提高了CO₂的扩散选择性,同时氮、硫元素的掺杂因为酸碱相互作用和良好亲和性有效提高了CO₂的吸附选择性。稳定性实验表明,PEBA/NSPC混合基质膜在360 h连续运行过程中气体分离性能稳定,具有较好的工业应用前景。     

功能化Zr-MOF强化混合基质膜CO2分离

混合基质膜（MMMs）在气体分离领域具有良好的应用前景,金属有机框架（MOFs）由于具有高孔隙率和有机连接基团,常被用作填料制备MMMs。但由于MOFs与聚合物的界面相容性问题,MMMs的气体分离性能提升受到限制。本文合成了功能化的Zr-MOF（UiO-66-AC）,并利用其与聚醚共聚酰胺（Pebax）共同制备了混合基质膜。填料中引入的羰基和羧基等基团提供了MOFs与聚合物基质之间较强的界面相互作用。与纯Pebax膜相比,UiO-66-AC/Pebax MMMs的气体渗透性能得到了显著提高。当填料质量分数为6%时,膜的CO₂渗透系数为102.4 Barrer,CO₂/N₂和CO₂/CH₄选择性分别为90.6和26.0,CO₂/N₂分离性能突破了Robeson上限(2008),表明该混合基质膜在CO₂的分离应用上具有潜力。     

金属有机框架/聚酰亚胺混合基质膜的研究进展

聚酰亚胺是一种具有高热稳定性和良好成膜性的高分子材料,但聚酰亚胺膜在气体分离方面的应用效果较差。金属有机框架材料在气体分离中有较好的应用前景。用两者制备的混合基质膜,可以综合其各自的优点,提高对气体的选择渗透性。本文综述了采用金属有机框架材料、金属有机框架材料改性以及添加其他聚合物基底制备混合基质膜,对气体分离效果的影响,并对这种混合基质膜在气体分离领域的使用效果进行了分析,对这种混合基质膜面临的挑战进行了讨论与展望。     

MOFs基材料制备混合基质膜用于O2/N2分离的研究进展

金属有机框架（metal-organic frameworks,MOFs）材料具有多孔、孔径易于调节、高的比表面积等优点,用于改善传统聚合物膜的缺点,制得的混合基质膜具有较好的气体分离性能。混合基质膜中的填料和聚合物基质的性质、填料和聚合物基质间的界面相互作用等影响着膜的气体渗透性和选择性,本文着重介绍混合基质膜中填料尺寸、形貌和聚合物性质对混合基质膜气体分离性能的影响,以及相应的改性方法,为氧氮分离的MOFs基混合基质膜提供新的思路。     

ZIF-L/PDMS混合基质膜蒸气渗透耦合发酵强化乙醇生产效率的研究

蒸气渗透（VP）膜分离不存在膜污染风险,在生物乙醇生产中具有广阔的应用前景。将聚二甲基硅氧烷（PDMS）膜和以二维沸石咪唑骨架（ZIF-L）为填充基质制备的PDMS（ZIF-L/PDMS）混合基质膜,分别用于VP膜分离与菊粉水解液发酵制乙醇过程的耦合,分析了二者在耦合过程中的分离性能和发酵性能。探究了不同膜分离方式、不同类型膜及操作条件对膜分离性能的影响。实验结果表明,当料液浓度为5%（质量）、蒸气循环流量为1.5 L·min^-1时,ZIF-L/PDMS混合基质膜的VP性能高于渗透汽化（PV）,归一化总通量达到1148.78 g·m^-2·h^-1,分离因子高达19.14,显著提升了乙醇分离性能。ZIF-L/PDMS混合基质膜用于VP耦合发酵,实现了耦合过程的高渗透性和乙醇选择性,与文献报道相比,乙醇移除效果最优,乙醇产率和时空产率分别达到0.421 g·g^-1、3.07 g·L^-1·h^-1,两个指标明显高于单独发酵,极大地提高了乙醇生产效率。因此,ZIF-L/PDMS混合基质膜在原位分离发酵乙醇方面具有很大的应用潜力。     

PVA/ZIF-8-NH2混合基质膜的制备及渗透汽化分离性能

通过将氨基改性ZIF-8-NH₂加入聚乙烯醇(PVA)制备了混合基质膜。采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、接触角和溶胀度测定等方法表征混合基质膜的结构与性能。通过混合基质膜渗透汽化正丁醇脱水实验发现,ZIF-8-NH₂含量为10%的混合基质膜,在40℃下的85%正丁醇/水混合液中的渗透汽化分离性能相对较好。     

渗透汽化膜在生物质ABE富集分离中的应用研究进展

综述了目前ABE富集分离的各种渗透汽化膜技术及发展现状,其中主要包括聚合物基质膜和混合基质膜两大类,着重介绍了金属有机骨架材料(MOF)、沸石、离子液体(IL)等掺杂材料制备的混合基质渗透汽化膜,总结了混合基质膜的掺杂制备、工艺参数、影响因素等,指出了渗透汽化膜分离技术在ABE分离中的瓶颈,并展望了渗透汽化膜技术在未来的发展方向。     

聚酰亚胺渗透汽化膜改性研究进展

详细综述了用于渗透汽化分离的聚酰亚胺膜的改性研究进展,重点评述了共聚（改变主链结构、侧基结构和引入特殊功能性单体）、填充（无机物填充和有机物填充）、交联、共混以及表面改性5种改性方法,包括其反应原理、设计思路以及对聚酰亚胺膜分子结构和分离性能的影响等。同时通过比较不同改性方法的研究结果,分析了几种改性方法在渗透汽化膜分离方面的优点和不足。在此基础上,对聚酰亚胺渗透汽化膜的改性方法发展方向和研究前景进行了总结。     

β-环糊精/聚醚共聚乙酰胺填充膜的制备及渗透汽化分离水中微量苯酚

将β-环糊精（β-CD）添加到聚醚共聚乙酰胺（PEBA）中制备β-环糊精/聚醚共聚乙酰胺填充膜（β-CD-f-PEBA）,用于苯酚-水的渗透汽化分离研究。SEM、FTIR表明β-环糊精在膜中分散均匀且与膜结合紧密,与膜间只有氢键相互作用而未发生化学交联。拉伸实验表明膜的拉伸强度和断裂强度均随着β-CD添加量的增加先减小后增大。采用基团贡献法计算了PEBA、苯酚及水的溶解度参数,证明PEBA膜对苯酚具有较高的选择吸附性。通过溶胀验证膜对苯酚的选择吸附性能,膜对苯酚的吸附量度随着料液中苯酚浓度和膜中β-CD添加量的增加而增加。考察了PEBA和β-CD-f-PEBA膜的渗透汽化性能,当β-CD填充量为0.5%（质量）时,分离效果最佳,渗透通量和分离因子分别为3062.9 g·m^-2·h^-1和43.3。通过Arrhenius方程计算苯酚和水的渗透活化能分别为97.19和52.12 kJ·mol^-1。重复实验表明β-CD-f-PEBA膜的操作稳定性良好。     

Poly(vinyl alcohol)/carboxyl graphene mixed matrix membranes: High-power ultrasonic treatment for enhanced pervaporation performance

High-power ultrasonic treatment was conducted during the mixing process to obtain poly(vinyl alcohol) (PVA)/carboxyl graphene (CG) mixed matrix membranes (MMMs). Results from X-ray photoelectron spectrometer and thermogravimetric analysis confirmed the enhanced esterification reaction. The increased amorphous region and free volume were investigated by wide-angle X-ray diffraction and positron annihilation lifetime spectroscopy. Scanning electron microscope and atomic force microscope measurements suggested that ultrasonic could uniformly disperse CG in PVA polymer matrix. The mechanical properties and hydrophilicity of as-prepared membrane were enhanced due to ultrasonic treatment. The permeation flux and separation factor of PVA/CG-US membrane for 90 wt % ethanol aqueous solution were 0.79 kg m⁻² h⁻¹ and 860, respectively. For methanol (15 wt %)/methyl tert-butyl ether mixture, its permeation flux and separation factor were also increased significantly compared with membranes without ultrasonic treatment. Due to the simplicity of the ultrasonic process and the versatility of the inorganic fillers, this method may contribute to the design of various MMMs and extend the application of these membranes in different uses. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48526.     

Fabrication of PEBA/ceramic nanocomposite membranes in gas sweetening

Poly (ether-block-amide) (PEBA)/ceramic nanocomposite hybrid membranes were fabricated by dip-coating of ceramic nanocomposite porous support in PEBA solution and their performance in gas separation (CO₂ and N₂) was examined. Tubular supports were used as substrates for hybrid membranes and Poly (ether-block-amide) was applied as a selective layer. PEBA based on N6 and PEO was synthesized via a two step process. The formation of new ester bond between N6 and PEO in the synthesized copolymer was proved by FT-IR spectroscopy. AFM micrographs indicated that the morphology is the dispersion of high stiffness nanostructured PA domains in the amorphous region of PEO matrix. Experimental results showed that at high concentration of coating solution, a uniform PEBA layer was formed on the porous ceramic support with higher performance for the separation of CO₂/N₂ binary gas mixture.     

碳纳米管/环糊精金属有机骨架协同强化混合基质膜的CO2分离

为了实现混合基质膜中CO₂的高效分离,设计了羧基化多壁碳纳米管(CNT)和氨基化β-环糊精金属有机骨架(β-CD MOF)双填料(CM),并将其引入磺化聚醚醚酮(SPEEK)基质中,在膜内同时构建CO₂扩散通道和亲和位点,增强了混合基质膜的分离性能。采用FTIR和BET表征了CM的化学结构和孔结构,借助膜的SEM、FTIR和力学性能表征了填料-聚合物界面相互作用。研究了CM的合成比例、含量、压力、温度和混合气等因素对混合基质膜分离性能的影响。结果表明：CM与SPEEK之间具有良好的相容性并为气体分子提供了快速的传递通道。在改性CNT与MOF的质量比为5∶5、添加量为7%(质量)以及0.1 MPa和25℃的条件下,混合基质膜的分离性能最优,CO₂渗透性为844 Barrer,CO₂/N₂选择性为84,与纯SPEEK膜相比,分别提升了178%和163%,超过2019年上限。羧基化CNT的直孔通道缩短了CO₂的扩散路径,同时改性β-CD MOF表面的氨基载体提升了CO₂的溶解性,两者协同提高了混合基质膜的分离性能。此外,负载双填料的膜比单独负载相同含量的羧基化CNT或氨基化MOF的膜具有更好的分离性能。在360 h的测试过程中,混合基质膜保持较好的分离稳定性。     

碳纳米管/环糊精金属有机骨架协同强化混合基质膜的CO2分离

为了实现混合基质膜中CO₂的高效分离,设计了羧基化多壁碳纳米管(CNT)和氨基化β-环糊精金属有机骨架(β-CD MOF)双填料(CM),并将其引入磺化聚醚醚酮(SPEEK)基质中,在膜内同时构建CO₂扩散通道和亲和位点,增强了混合基质膜的分离性能。采用FTIR和BET表征了CM的化学结构和孔结构,借助膜的SEM、FTIR和力学性能表征了填料-聚合物界面相互作用。研究了CM的合成比例、含量、压力、温度和混合气等因素对混合基质膜分离性能的影响。结果表明：CM与SPEEK之间具有良好的相容性并为气体分子提供了快速的传递通道。在改性CNT与MOF的质量比为5∶5、添加量为7%(质量)以及0.1 MPa和25℃的条件下,混合基质膜的分离性能最优,CO₂渗透性为844 Barrer,CO₂/N₂选择性为84,与纯SPEEK膜相比,分别提升了178%和163%,超过2019年上限。羧基化CNT的直孔通道缩短了CO₂的扩散路径,同时改性β-CD MOF表面的氨基载体提升了CO₂的溶解性,两者协同提高了混合基质膜的分离性能。此外,负载双填料的膜比单独负载相同含量的羧基化CNT或氨基化MOF的膜具有更好的分离性能。在360 h的测试过程中,混合基质膜保持较好的分离稳定性。     

Separation of acid–water mixtures by pervaporation using nanoparticle filled mixed matrix copolymer membranes

BACKGROUND: Low energy and less expensive membrane based separation of acetic acid‐water mixtures would be a better alternative to conventional separation processes. However, suitable acid resistant membranes are still lacking. Thus, the objective of the present study was to develop mixed matrix membrane (MMM) which would allow high flux and water selectivity over a wide range of feed concentrations of acid in water. RESULTS: Three MMMs, namely PANBA0.5, PANBA1.5 and PANBA3 were made by emulsion copolymerization of acrylonitrile (AN) and butyl acrylate (BA) with 5.5:1 comonomer ratio and in situ incorporation of 0.5, 1.5 and 3 wt%, sodium montmorilonite (Na‐MMT) nanofillers, respectively. For a feed concentration of 99.5 wt% of acid in water the membranes show good permeation flux (2.61, 3.19, 3.97 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and very high separation factors for water (1473, 1370, 1292 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at 30 °C. Similarly for a dilute acid–water solution, i.e. for 71.6 wt% acid the membrane showed a very high thickness normalize flux (8.67, 9.44, 11.56 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and good water selectivity (101.7, 95.3, 79 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at the same feed temperature. The permeation ratio, permeability, diffusion coefficient and activation energy for permeation of the membranes were also estimated. CONCLUSION: Unlike most of the reported membranes, the present MMMs allowed high flux and selectivity over a wide range of feed concentrations. These membranes may also be effective for separating other similar organic‐water mixtures. Copyright © 2012 Society of Chemical Industry     

Separation of phenol from aqueous solution by membrane pervaporation using modified polyurethaneurea membranes

Hydroxy‐terminated polybutadiene‐based porous and nonporous polyurethaneurea membranes were prepared and used to study the phenol separation efficiency from dilute aqueous solution. The porosity was developed by incorporation of lithium chloride in polymer matrix with subsequent leaching of the same in hot water. The porous membrane showed higher phenol flux over that of nonporous membrane. Permeate containing about 97 wt % phenol was obtained from feed containing 7 wt % phenol, when pervaporation was carried out with porous polyurethaneurea membrane at 75°C. The activation energies for diffusion, permeation, and pervaporation were calculated from Arrhenius plots. From the activation energy values, it was observed that the pervaporation process became easier with increased phenol concentration in the feed and porosity of the membrane used. The membrane boundary resistance was observed to decrease with increase in temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1857–1865, 2006     

Separation of aqueous phenol through polyurethane membranes by pervaporation. III. Effect of the methylene group length in poly(alkylene glycols)

Separation of phenol from dilute aqueous solution through polyurethane membranes by pervaporation was investigated. The effect of the methylene group length in poly(alkylene glycols) on permselectivity and solubility of phenol was studied. The poly(alkylene glycols) were obtained by polycondensation of 1,6‐hexanediol, 1,8‐octanediol, and 1,10‐decanediol with a sulfuric acid catalyst. Polyethyleneglycol and polytetramethyleneglycol were commercially available. Progress of the polymerization in the poly(alkylene glycols) was confirmed by FTIR, ¹H‐NMR analysis, and SEC measurement. The polyurethanes were obtained by polyaddition reaction of 1,6‐hexamethylenediisocyanate and the poly(alkylene glycol), and were confirmed by FTIR analysis and SEC measurement. The phenol concentration in a permeate liquid increased from 25.1 to 36.2 wt %, and the phenol partial flux also increased from 49.3 to 68.9 g · m⁻² · h⁻¹ with increasing the methylene group length in the poly(alkylene glycols), whereas the water partial flux slightly decreased. As a result of sorption measurements, the change in the degree of swelling was small, and the phenol concentration in the membrane increased from 42.1 to 70.8 wt %. The increase in the methylene group length of the poly(alkylene glycols) should contribute to an increase in the hydrophobicity of the polyurethane so that the solubility of phenol to the membrane should increase. The phenol concentration in the permeate liquid and the phenol partial flux increased with an increase in the methylene group length of the poly(alkylene glycols) due to the increase in the phenol solubility for the polyurethane membranes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 654–664, 2000