功能化PVI/MOR杂化膜的制备及乙酸脱水分离性能

通过自由基接枝聚合的方法将1-乙烯基咪唑单体接枝到MOR沸石膜的表面,制备出一种新型的亲水性的聚(1-乙烯基咪唑)/丝光沸石(PVI/MOR)杂化膜.并通过扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶红外漫反射光谱(DRIFTS)和热重分析等来表征膜的形貌和特性.将膜应用于乙酸脱水分离,考察了不同Ⅵ单体浓度和进料浓度对膜的渗透汽化性能的影响.分析得知以15%的Ⅵ单体浓度制备的PVI/MOR杂化膜具有最好的分离性能,在80℃下和71%～94%的进料浓度范围内均达到理想选择性分离,也就是说在透过侧产品水的含量达到100%.这些实验结果表明将PVI基团接枝到MOR沸石膜层能实现真正意义上的功能化修补膜的缺陷和大大提高膜的分离性能的目的.     

交联型氧化石墨烯复合膜在水处理中的应用研究进展

近年来,氧化石墨烯基纳米材料作为一种新型的膜材料,以其优异的机械强度、良好的物理化学稳定性和独特的二维结构,在水处理方面表现出优异的分离性能.本文综述了氧化石墨烯基膜的制备方法,介绍了交联型氧化石墨烯复合膜在纯水渗透通量、无机盐截留性能、膜稳定性方面的性能特点以及在超滤、纳滤和反渗透领域的研究进展,并对其在水处理领域的...     

氧化石墨烯羧基化改性研究

利用氢溴乙酸对羧基氧化石墨烯(GO-COOH)羧酸进行羧基中的化合物改性,制备了羧基中的化合物氧化石墨烯(GO-COOH-COOH),通过傅里叶光谱变换和近红外光谱、原子力光谱显微镜、热重力学分析对其结构进行了表征.然后我们采用不同物理用量的产物GO-COOH-COOH通过各种物理共轭预混分别反应制备了改性甲基聚丙烯酸...     

羧基化改性对PAN热交联膜孔结构及性能的影响

作为热塑性材料,聚丙烯腈不对称膜在热交联的过程中会发生热熔融,导致孔融并。以非溶剂相转化(NIPS)法制备了聚丙烯腈基不对称(PAN)膜,采用NaOH碱性水解工艺,经过羧基化改性和热交联制得具有丰富海绵状孔及指状孔结构的羧基化PAN基热交联(H-TPAN)膜,研究了NaOH浓度对PAN及后处理膜结构与性能的影响。结果表明,羧基化对PAN膜进行改性处理,能够在热交联阶段促进氰基团环化和氧化反应,提高H-TPAN膜的交联程度,避免膜孔在高温下的热融并,保持PAN热交联膜通量。PAN膜在热交联过程中性能最优的羧基化条件为：NaOH浓度0.4 mol·L^-1、羧基化时间1 h、羧基化温度60℃。同时,羧基化改性膜表现出优异的热稳定性和良好的耐溶解性。     

PVA复合膜的渗透汽化性能研究：（Ⅰ）操作条件和长期运行的影响

本文研究了以ＰＡＮ膜为支撑层的ＰＶＡ复合膜分离醇水溶液的性能。着眼于工业应用，揭示了渗透汽化操作条件对分离性能的影响，展示了长期运行时的分离性能。结果表明，ＰＶＡ复合膜具有高渗透通量和优异分离率，长期运行性能稳定。     

氧化石墨烯杂化分子印迹复合膜制备及性能研究

采用改进的Hummers法,通过冷冻干燥制备了氧化石墨烯(GO)。以辛弗林盐酸盐为模板分子,水溶性的丙烯酰胺为功能单体,离子液体(溴代1-丁基-3-甲基咪唑)为致孔剂,把GO加入聚合液中,制备了GO杂化的分子印迹复合膜(GO-MIM)。利用透射电镜、扫描电镜、X射线衍射和红外光谱等方法对GO及GO-MIM进行了表征。通过将分子印迹膜技术与GO相结合,明显提高了分子印迹膜的力学性能。吸附及渗透实验表明,GO-MIM可在纯水溶剂体系,对辛弗林盐酸盐具有很好的选择性吸附能力和优先透过能力,体现了明显的分子印迹效果。     

聚乙烯醇/超支化聚酯交联渗透汽化膜的制备及其溶解扩散性能分析

将超支化聚酯（HBPE）与聚乙烯醇（PVA）共混交联制备了PVA/HBPE交联渗透汽化膜,研究了PVA/HBPE交联膜内的溶解扩散及渗透汽化性能。结果表明,随着温度的增加,水在交联膜内的渗透系数（Pwater）增加,且变化趋势与纯水通量一致,在55 ℃时达到最大值71.952 g/m2·h;随着HBPE含量的增加,渗透系数Pwater及纯水通量呈现增加的趋势,当HBPE含量为40 %时,纯水通量达到最大值185.726 g/m2·h。     

渗透汽化有机-无机杂化膜研究进展

近年来,有机-无机杂化膜的研究受到了广泛关注,随着有机-无机杂化膜制备方法的多样化和分离性能的提高,其研究前景也越来越广阔.该文首先分析了有机-无机杂化膜相比于普通无机膜和有机膜在结构和性能上存在的优势,其次综述了有机-无机杂化膜的制备方法以及其在醇类、有机酸等有机溶剂或有机混合物中的分离提纯应用,重点讨论了其在渗透汽...     

溴化丁基橡胶的热可逆共价交联

利用季铵化反应的热可逆特性,采用含有叔胺官能团的聚合物替代传统交联剂,研究了溴化丁基橡胶(BIIR)的交联反应活性及交联的热可逆性.结果表明,硫化温度和硫化时间对交联BIIR的凝胶含量有显著影响,在160 ℃×30 min的硫化条件下,交联剂呈现出较高的交联活性;不同温度下的转矩测定和190 ℃二次热压的塑性流动证实交联BIIR具备热塑加工性.     

用于渗透汽化的有机—无机杂化膜研究进展

近年来,有机-无机杂化膜的研究受到学术界广泛关注,随着有机-无机杂化膜制备方法的多样化和分离性能的提高,其研究前景也越来越广阔。该文首先分析了有机-无机杂化膜相比于普通无机膜和有机膜在结构和性能上存在的优势,其次综述了有机-无机杂化膜的制备方法以及其在醇类、有机酸等有机溶剂或有机混合物中的分离提纯应用,重点讨论了其在渗透汽化中的应用。最后,对有机-无机杂化膜的研究前景进行展望。未来有机-无机杂化膜的研究应借助于新的计算工具,侧重于材料的选择或制备方法的改进,如探索具有多功能化学基团和具有明确层次结构的多孔填料的聚合物材料等,使有机-无机杂化膜具有更加广阔的应用前景。     

Thin film composite sodium alginate membranes for dehydration of acetic acid and isobutanol

Dehydration of widely used organic solvents such as acetic acid (AA) and isobutanol (IB) is challenging tasks, which form close boiling mixtures with water. Sodium alginate (SA) thin film composite membranes were prepared and crosslinked with 2,4‐toluene diisocyanate (TDI) and glutaraldehyde for dehydration of IB and AA/water mixtures through pervaporation (PV). The crosslinked and uncrosslinked SA composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and universal testing machine for intermolecular interactions, crystalline nature, thermal stability, surface morphology, and tensile strength, respectively. At a feed composition of 98 wt % IB and 95 wt % AA aqueous solutions, the TDI crosslinked SA composite membrane exhibited separation factors of 3229 and 708 with reasonable fluxes of 0.021 and 0.012 kg m^?2 h^?1, respectively. The results obtained in the study for IB and AA systems were compared with other SA membranes reported in the literature. The membranes appeared to have potential for commercial PV ability to dehydrate the solvents up to desirable purity levels (>99%) and feasibility of preparing them in a composite form which would enable scale‐up into modular configurations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40018.     

Properties and pervaporation performance of poly(vinyl alcohol) membranes crosslinked with various dianhydrides

In this work, three dianhydrides with similar chemical structures, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), 4,4′‐oxydiphthalic anhydride (ODPA), and pyromellitic dianhydride (PMDA), are employed for the crosslinking modification of poly(vinyl alcohol) (PVA) membranes for ethanol dehydration via pervaporation. The changes in crosslinking degree, surface hydrophilicity, and glass‐transition temperature are investigated and compared. Compared to the pure PVA membrane, all crosslinked membranes show higher fluxes but lower separation factors, because of the higher fractional free volume and the lower hydrophilicity by the crosslinking of the PVA matrix, respectively. In addition, all crosslinked PVA membranes exhibit similar flux, and the separation factor presents a decreasing order of PVA/PMDA‐2 > PVA/ODPA‐2 > PVA/BTDA‐2, which is in the reverse order of their hydrophilicity, probably because of the reduction in the swelling resistance. With the PMDA content increasing from 0.01 to 0.04 mol/(kg PVA) in the PVA/PMDA crosslinked membranes, the crosslinking degree is enhanced and the hydrogen bonding is weakened, resulting in a flux increase from 120.2 to 190.8 g m^?2 h^?1, but the separation factor declines from 306 to 58. This work is believed to provide useful insight on the chemical modification of PVA membranes for pervaporation and other membrane‐based separation applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46159.     

Ionic conductivity and related properties of crosslinked chitosan membranes

Crosslinked chitosan membranes were prepared with a relatively low degree of crosslinking with epichlorohydrin and glutaraldehyde as crosslinking agents under heterogeneous and homogeneous conditions, respectively. The tensile properties, crystallinity, swelling index, and ionic conductivity of the crosslinked membranes were investigated. A significant decrease in the crystallinity and a large change in the swelling ratio of the crosslinked membrane were observed. In comparison with the uncrosslinked chitosan membrane, when the chitosan membrane was crosslinked with an appropriate degree of crosslinking under homogeneous conditions, its ionic conductivity after hydration for 1 h at room temperature increased by about one order of magnitude. In addition, with a lower concentration of the crosslinking agent, the tensile strength and breaking elongation of the crosslinked membrane were almost unchanged. Moreover, up to a critical value, the tensile strength of the membrane increased gradually, and the breaking elongation decreased slowly. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 306–317, 2003     

Poly(ethylene glycol) crosslinked sulfonated polysulfone composite membranes for forward osmosis

Forward osmosis (FO) membranes were prepared by a coating method with poly(ethylene glycol) crosslinked sulfonated polysulfone (SPSf) as a selective layer. The poly(ether sulfone)/SPSf substrate was prepared by phase inversion. The composite membranes were characterized with respect to membrane chemistry (by attenuated total reflectance/Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy), hydrophilicity (by static contact angle measurement), and surface morphology (by scanning electron microscopy and atomic force microscopy). The FO performance was also characterized. The effects of the crosslinker concentration on the hydrophilicity and FO performance were investigated. The crosslinked membrane exhibited a high hydrophilicity with a lowest contact angle of 15.5°. Under FO tests, the membranes achieved a higher water flux of 15.2 L m^?2 h^?1 when used against deionized water as the feed solution and a 2 mol/L sodium chloride (NaCl) solution as the the draw solution. The membranes achieved a magnesium sulfate rejection of 96% and an NaCl rejection of 55% when used against a 1 g/L inorganic salt solution as the feed solution and a 2 mol/L glucose solution as the draw solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43941.     

Gas‐separation properties of amine‐crosslinked polyimide membranes modified by amine vapor

The modification of a polyimide (PI) membrane by aromatic amine vapor was performed in this work to increase the crosslinking of the membrane and to study the effect on gas permeability and the corresponding selectivity. The single‐gas permeability of the membranes at 35 °C was probed for H₂, O₂, N₂, CO₂, and CH₄. From the relationship between the combinations of gases and ideal permselectivities, this study showed that amine‐crosslinked PI membranes tended to increase gas permselectivities exponentially with the increasing difference in gas kinetic diameter. Moreover, this study illustrated that the permeability of the membranes was influenced by the formation rate of amine‐crosslinked networks or chemical structures after the reaction. The membranes had the highest level of permselectivities among crosslinked PI membranes for O₂/N₂, and the H₂/CH₄ permselectivity increased 26 times after vapor modification. Furthermore, the modification method that used aromatic amine vapor produced thin and strongly modified layers. These findings indicate that modification is an advantageous technique for improving gas‐separation performance, even considering thinning. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44569.     

Preparation and characterization of high-performance dehydrating pervaporation alginate membranes

In a previous work, sodium alginate dense membranes demonstrated a good combination of selectivity and permeation flux for dehydrating organic solvents by pervaporation. In this article, the pervaporation performances of alginate composite membranes has been investigated to find out the best condition of membrane formation and the optimum operating conditions. Some ultrafiltration membranes made of poly-(vinylidene fluoride), polyacrylonitrile, and hydrolyzed polyacrylonitrile—either commercially available or prepared in our laboratories—were used as supports for the composite membranes. Sodium alginate dense membranes, modified through ion exchange of sodium with multivalent metal ions (such as Al³⁺, Cr³⁺, Fe³⁺, and Mg²⁺) have also been prepared, and their permselectivities have been tested for the water–ethanol mixture. An interesting stability of the modified membranes in long-term operation is expected. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 959–968, 1998     

Transport properties of graphene oxide nanofiltration membranes: Electrokinetic modeling and experimental validation

There is a need for developing reliable models for water and solute transport in graphene oxide (GO) membranes for advancing their emerging industrial water processing applications. In this direction, we develop predictive transport models for GO and reduced-GO (rGO) membranes over a wide solute concentration range (0.01–0.5 M) and compositions, based on the extended Nernst–Planck transport equations, Donnan equilibrium condition, and solute adsorption models. Some model parameters are obtained by fitting experimental permeation data for water and unary (single-component) aqueous solutions. The model is validated by predicting experimental permeation behavior in binary solutions, which display very different characteristics. Sensitivity analysis of salt rejections as a function of membrane design parameters (pore size and membrane charge density) allows us to infer design targets to achieve high salt rejections. Such models will be useful in accelerating structure-separation property relationships of GO membranes and for separation process design and optimization.     

Preparation of crosslinked alginate composite membrane for dehydration of ethanol–water mixtures

The purpose of this article was to develop new membranes with a high selectivity and permeation rate for separation of an alcohol/water system. Crosslinked alginate composite membranes were prepared by casting an aqueous solution of alginate and 1,6‐hexanediamine (HDM) onto a hydrolyzed microporous polyacrylonitrile (PAN) membrane. The influence of hydrolysis of the support membrane and crosslinking agent content in a dense layer on the selectivity and flux was studied and it was shown that both could improve the separation performance of the composite membrane greatly. The countercation of alginate coatings as a dense separating layer also influenced the separation properties of the membrane, which was better for K⁺ than for Na⁺. This novel composite membrane with K⁺ as a counterion has a high separation factor of 891 and a good permeation rate of 591 g m⁻² h⁻¹ for pervaporation of a 90 wt % ethanol aqueous solution at 70°C. At the same time, SEM micrographs showed that the pore structure of the PAN microporous membrane is changed by hydrolysis. The reason for the influence of the preparation conditions on the separation performance of the novel membrane is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3054–3061, 2000