Fabrication of anti-fouling polyamide nanofiltration membrane by incorporating streptomycin as a novel co-monomer

Polyamide (PA) thin-film composite (TFC) nanofiltration (NF) membrane has extremely broad application prospects in separation of monovalent/divalent inorganic salts mixed solution. However, membrane fouling is the main obstacle to the application of PA, TFC and NF membrane. Streptomycin (SM) is a hydrophilic antibiotic containing a large number of hydroxyl and amino groups. In this work, the NF membrane was prepared via interfacial polymerization (IP) between trimesoyl chloride (TMC) in the organicphaseand SM/piperazine (PIP) mixture in theaqueousphase. The NF membrane structure and performance were characterized in detail. The results showed that SM successfully participated in the IP. The negative charge and hydrophilicity of membrane surface were improved. The prepared membrane exhibited good anti-adhesion and anti-bacterial performance. Additionally, when the SM concentration was 2%, the prepared membrane exhibited the optimal permselectivity. The water permeance was 89.4 L·m^-2·h^-1·MPa^-1. The rejection of NaCl and Na₂SO₄ were 17.17% and 97.84%, respectively. The NaCl/Na₂SO₄ separation factor of the SM2-PIP/TMC membrane in 1000 mg·L^-1 NaCl and 1000 mg·L^-1 Na₂SO₄ mixed solution was 40, which was 3.3 times that of PIP/TMC membrane. It indicated that SM2-PIP/TMC demonstrated excellent monovalent/divalent salts separation performance. This work provided an easy and effective approach to preparing anti-fouling NF membrane while possessing superior monovalent/divalent salts separation performance.     

Preparation and separation properties of polyamide nanofiltration membrane

Utilizing an interfacial polymerization technique for the preparation of a polymeric composite nanofiltration membrane, both high permeation flux of water and high salt rejection can be achieved. Synthesis conditions, such as concentration of monomer, reaction time, and swelling agent, significantly affected the separation performance of composite membranes. The composite polyamide membrane had a permeation rate of ～2–5 gallon/ft²/day (gfd) and a salt rejection rate of ～94–99% when 2000 ppm aqueous salt solution was fed at 200 psi and 25°C. Also, a higher performance nanofiltration membrane could be prepared by suitably swelling the support matrix in the period of polymerization. The results of various feed concentrations showed that permeate flux decreased with increasing salt concentration in the feed solution. This result may be due to concentration polarization on the surface of polyamide membranes. The separation performance of polyamide membranes showed an almost independent relationship with operation pressure until it was up to 200 psi. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1112–1118, 2002     

耐污染聚酰胺复合纳滤膜的制备及性能

以哌嗪(PIP)和均苯三甲酰氯(TMC)为反应单体,以聚乙烯醇(PVA)为添加剂,通过界面聚合法在聚砜超滤基膜上制备了复合纳滤膜,主要研究了PVA、PIP、TMC单体浓度、热处理条件对复合膜性能的影响,并通过扫描电子显微镜(SEM)、原子力显微镜(AFM)对复合纳滤膜结构和形貌进行表征。研究表明,PVA能够提高膜通量,增强膜亲水性,提高膜表面光滑度。最佳制膜条件是:PIP浓度为3.0 g/L,TMC浓度为1.0 g/L,PVA浓度为0.54 g/L,界面聚合时间为1 min,热处理温度为50℃,热处理时间10 min。制备的纳滤膜在处理Na2SO4、MgSO4、NaCl和MgCl2等4种盐溶液时,其截留性能与陶氏NF-270和星达NFX膜相近,而在深度处理造纸脱墨废水时,也表现出良好的分离性能和耐污染性能。     

Fouling studies of a polyamide nanofiltration membrane by selected natural organic matter: an analytical approach

The present study compares the fouling properties of two selected and well-characterized hydrophobic (denoted HPOA) and hydrophilic (denoted TPIA) natural organic matters (NOM) fractions with a commercial polyamide (PA) nanofiltration (NF) membrane (denoted NF-55). Analytical tools such as elemental analyses using microanalyses, specific UV absorbance, solid-state cross-polarization magic angle spinning (CPMAS) ¹³C-NMR, high pressure size exclusion (HPSEC) chromatography, HPLC system and acid/base titration for characterizing NOM fractions and contact angle, hydraulic permeability, streaming potential (SP) and observed rejection of a NaCl aqueous solution to evaluate the affinity of the PA material with both selected NOM fractions isolated from the Blavet river (Britany region, France). The PA material was found to be more sensitive to hydrophobic NOM adsorption leading to irreversible fouling with drastic modifications of the initial physico-chemical properties of the membrane: (a) increase of its hydrophobicity; (b) decrease of its hydraulic permeability associated with a decrease in its pore size and consequently (c) increase the observed rejection of salty solutions. The higher decrease in the performances of this PA NF membrane is observed for the more hydrophobic foulant, HPOA. At the same time a displacement of the isolectric point (IEP) of the membrane material was observed from 4.5 for the clean membrane (KCl 10⁻⁴ mol.L⁻¹) to 3.4 after HPOA sorption. At a lower pH range than the IEP, the effects of cations and H⁺ on the charge properties of the membranes increases near the shear plane, yielding more positive SP values. For the hydrophilic TPIA foulant no displacement of the IEP was observed. Then the results of SP experiments conducted through the membrane with a homemade apparatus has indicated that HPOA is more retained inside the pores as compared to the TPIA that was mainly sorbed at the surface of the membrane. Furthermore the membranes acidic-basis properties were amplified after foulants deposit in comparison to the cleaned membrane where a dominant specific sorption of monovalents and divalents ions occurred.     

丙烯酸接枝聚酰胺/聚醚酰亚胺复合纳滤膜的制备

为了提高复合纳滤膜的抗污染性能,采用紫外光照接枝法将丙烯酸接枝到聚酰胺/聚醚酰亚胺(PA/PEI)复合纳滤膜的皮层上,通过引入羧基基团来增加膜表面的亲水性。考察了丙烯酸单体质量分数、辐照时间对表面接枝率和膜分离性能的影响,并对优选的膜进行了抗污染性能测试。结果表明:丙烯酸质量分数与紫外辐照时间对膜分离性能的影响规律相同,膜通量随质量分数的增加与辐照时间的延长呈现先增加后减小的趋势,而截留率则保持基本不变,当丙烯酸质量分数2%,辐照时间2 min时,膜的通量达到13.12 L/(m2·h),较接枝前的11.94 L/(m2·h)略高;在含有1 g/L牛血清蛋白(BSA)的溶液中,接枝后的膜通量下降明显低于接枝前的膜。研究表明丙烯酸接枝可以有效改善膜表面亲水性,从而有利于提高膜的抗污染性能。     

用于混合一价盐分离的纳滤膜的制备及性能研究

针对有机颜料废水中单价相似离子（例如CH₃COO^-和Cl^-）分离难的问题,以表面活化能与脱水现象协同作用的分离机制为指导,在界面聚合中加入3,5-二氨基苯甲酸（DMA）来调控孔径、电性等性质,制备对醋酸根和氯离子具有高选择性的复合纳滤膜。XPS结果表明DMA参与界面聚合反应,形成疏松选择层;Zeta电位表明膜表面负电性增强。通过pH、操作压力等条件优化,得出0.6%（质量） DMA-TFC膜性能最佳,水通量较未改性复合膜提高44%,对于醋酸钠与硫酸钠的分离比达到15.0。本工作为相似离子分离纳滤膜的设计与制备提供了理论和实践基础,在颜料废水等水处理、物料分离等领域展现了良好的应用前景。     

Surface modification of polyamide nanofiltration membrane by grafting zwitterionic polymers to improve the antifouling property

A simple two‐step surface modification method of polyamide nanofiltration membrane, involving the activation of amide groups by formaldehyde and the subsequent cerium [Ce (IV)]‐induced graft polymerization of zwitterionic 3‐(methacryloylamino) propyl‐dimethyl‐(3‐sulfopropyl) ammonium hydroxide) (MPDSAH) monomers, was employed to improve membrane antifouling property. The membranes before and after modification were characterized by attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR), scanning electron microscopy, and atomic force microscopy. The changes in both surface chemical composition and morphology of membranes confirmed the successful graft polymerizations of MPDSAH onto polyamide nanofiltration membrane. The static water contact angle measurements showed that surface hydrophilicity of the modified membranes was significantly enhanced. As the MPDSAH concentration increased, the water flux of grafted membrane decreased gradually, while salt rejection increased slightly. The fouling experiments with bovine serum albumin solution demonstrated that modified membranes exhibited better resistance to protein fouling. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41144.     

聚酰胺/ZIF-8双层复合纳滤膜的制备及其性能研究

采用界面聚合和层层自组装法制备了具有双层分离层的聚酰胺/ZIF-8复合纳滤膜,并研究了界面聚合条件和ZIF-8自组装时间、层数对膜结构以及膜纳滤性能的影响。结果表明,具有磺酸基的界面聚合层和ZIF-8层通过配位键的化学作用具有很好的结合性。相对于只有一层分离层的聚酰胺膜,组装ZIF-8层后膜对甲基蓝的截留率有了明显提升;并且随着组装层数的增加,膜致密度增加,对于甲基蓝的截留率升高,但是通量有所下降。当ZIF-8层组装层数为2层时得到的复合纳滤膜,在0.5 MPa压力下,对于100 mg/L的甲基蓝溶液的通量为25.3 L/(m2·h),截留率达到96.5%,且分离性能保持稳定。     

热/可见光联合活化单过氧硫酸氢盐光敏降解罗丹明B

采用可见光/热/单过氧硫酸氢盐(PMS)体系氧化降解罗丹明B。在可见光条件下,考察了溶液温度、p H值、PMS初始浓度对罗丹明B降解动力学的影响。结果表明,在暗反应条件下,升高溶液温度,促进罗丹明B的降解,联合可见光光照,罗丹明B的降解率进一步增大。在酸性条件下,溶液p H值对罗丹明B降解的影响并不显著。在PMS初始浓度保持一定的范围内,罗丹明B的降解率与PMS初始浓度呈现出正相关关系。     

膜法分离有机物与无机盐的研究

采用界面聚合方法研制新型荷电纳滤膜,对有机物与无机盐进行分离,并系统研究了单体种类、酸吸收剂及乳化剂等因素对纳滤膜性能的影响。结果表明,聚乙烯亚胺（PEI）使膜呈宏观正电性,而2,5-二氨基苯磺酸（DIA）使膜呈宏观负电性;添加了PEI的膜经过热处理后截留率增加,而添加了DIA的膜经过热处理后截留率基本不变;选用均苯三甲酰氯（TMC）比间苯二甲酰氯（IPC）的聚合效果好;添加了十二烷基硫酸钠（SDS）和酸接收剂[n（Na2CO3）∶n（NaOH）=2∶1]后,膜的截留率均有不同程度的升高。     

AEPPS对超支化聚酰胺纳滤膜性能的影响

通过与均苯三甲酰氯(TMC)的界面聚合反应,将N-氨乙基哌嗪丙基磺酸盐(AEPPS)两性离子化合物引入超支化聚酰胺纳滤膜中以改善膜性能。着重考察AEPPS的质量分数对膜性能的影响。结果表明,与以往报道该物质与哌嗪或间苯二胺等小分子混合使用效果不同,当AEPPS与端氨基超支化聚酰胺混合作为水相反应物时,随着AEPPS质量分数的增加,膜的脱盐顺序发生变化,由Na₂SO₄>Mg SO₄>Mg Cl₂>Na Cl逐渐变为Mg SO₄>Mg Cl₂≈Na₂SO₄>Na Cl,最后是Mg SO₄>Na₂SO₄>Mg Cl₂>Na Cl。脱盐率先增大后降低,膜通量呈现相反趋势。AEPPS的引入增强了膜的亲水性及抗蛋白质吸附能力。当水溶液中AEPPS质量分数为0.6%时,制备的纳滤膜NF06在牛...     

Optimization of preparation conditions of polyamide thin film composite membrane for organic solvent nanofiltration

Separation performance of polyamide composite membranes is affected by several parameters during formation of thin upper layer via interfacial polymerization. We investigated the effect of various polyamide synthesis conditions on the performance of organic solvent resistant polyamide composite membranes through the model equations designed by 2-level fractional factorial design. The dewaxing solvent recovery was selected as separation process. Five factors were changed in two level includin; TMC concentration (0.05–0.1%), MPD concentration (1–2%), support immersion time in organic solution (2–4 min), support immersion time in aqueous solution (1–2 min), and curing temperature (70–80 °C). The resultant equations showed 93.48% and 94.82% of the variability (R _adj ² ) in data used to fit oil rejection and permeate flux models, respectively. The analysis of variance revealed that both models were high significant. It was also observed that TMC concentration, MPD concentration and immersion time in TMC have more pronounced effect on the oil rejection and permeate flux than other factors and interactions. Optimal polyamide preparation conditions were obtained using multiple response method for 94% oil rejection as target value. According to the results, the best value of permeate flux (8.86 l/(m²·h)) was found at TMC concentration of 0.1%, MPD concentration of 1.94%, immersion time in TMC of 3.88 min, immersion time in MPD of 1.95 min and curing temperature of 71.96 °C with desirability factor of 1.     

Development of a chlorine‐resistant polyamide nanofiltration membrane and its field‐test results

For the development of chlorine‐resistant nanofiltration membranes, a thin‐film‐composite membrane was prepared by the interfacial polymerization of N‐phenylethylenediamine and 1,3,5‐benzenetricarbonyl trichloride on a microporous polysulfone support substrate. The polymerization on the substrate surface was confirmed by Fourier transform infrared measurements, and membrane surface properties such as the roughness and ζ potential were characterized. Rejections of NaCl and isopropyl alcohol of the prepared membrane were 95 and 50%, respectively. The membrane showed much higher chlorine resistance than a commercial polyamide membrane when the membranes were immersed in an aqueous NaOCl solution. A field test was carried out with a spiral‐type membrane module. Tap water was treated by this module for more than 70 days under the condition of continuous NaOCl injection. The prepared membrane module was quite stable, and no distinguished change in the rejection and flux was recognized. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Ionic liquid-induced deep grafting of polyelectrolyte to reform polyamide layer for antifouling nanofiltration membrane

Surface grafting has been widely used to tune hydrophilicity and chargeability of nanofiltration membranes for reducing membrane fouling potential. However, surface grafting typically leads to a significant pore narrowing and resultant permeability loss, and monocharged surface still struggles to resist mixed foulants with different charges. Herein, ionic liquid (IL)-ethanol (EtOH) solution containing polyethyleneimine (PEI) is used to rearrange the nascent polyamide layer. The high affinity of IL to the PA layer and the low diffusion steric hindrance of EtOH contribute to the polyamide swelling and PEI deep grafting, during which the “self-regulation” effect (larger pores would be filled with more PEI molecules) narrows the pore size distribution and enhances hydrophilicity. The nearly charge-neutral and smooth separation layer shows impressive antifouling capacity to hydrophobic macromolecules and mixed charged molecules, along with long-term operating stability for real wastewater treatment. This study emphasizes the importance of solvent properties on the membrane grafting behavior.     

Effect of pH on the rejection of inorganic salts and organic compound using nanofiltration membrane

Nanofiltration (NF) has recently received increased attention as a possible tertiary treatment process providing high rejection of solutes and high water flux rate. In this research, solute separation experiments using NF membranes were made with inorganic salts including heavy metal and organic compounds in different pH levels. The rejection of inorganics from feed solution was found to be dependent on the electric charge of membrane as well as the ionic radius and valence of ion. The divalent cation appeared to reduce the potential of negatively charged membrane to lower the rejection of ion. The results of organic compounds showed that the rejection could be estimated from the pKa value and molecular weight of organics, and the pH of the feed solution.     

Separation of humic acid with nanofiltration polyamide composite membranes

Humic acid, a natural organic matter, was separated with a polyamide (PA) composite membrane with a molecular weight cutoff (MWCO) of 500 g/mol. The PA composite membrane was prepared by the interfacial polymerization of piperazine and trimesoyl chloride on a polysulfone support with an MWCO of about 30,000 g/mol. The separation conditions through the membrane were varied, and factors affecting the permeation performance of the membranes, such as the concentration, pH, and storage time of the humic acid solutions, were studied. The surface chemistry of the membrane changed dynamically as a function of the operating time during the permeation tests, and the size and ζ potential of the colloid of humic acid solutions under different conditions were characterized with a ζ potentiometer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2847–2853, 2002     

氧化石墨烯/碱式硫酸铝掺杂聚醚砜/聚酰胺复合纳滤膜的制备及其性能

先由氧化石墨烯（GO）、硫酸铝和尿素通过水热法制得氧化石墨烯/碱式硫酸铝（GO-BAS）复合物,继与哌嗪（PIP）溶液共混作为水相;均苯三甲酰氯（TMC）溶于正己烷作为有机相;采用界面聚合法使两相单体在聚醚砜（PES）基膜表面形成聚酰胺（PA）功能层,制得氧化石墨烯/碱式硫酸铝复合物掺杂的聚醚砜/聚酰胺（PES-PA-GO-BAS）复合纳滤平板膜,并在较低的工作压力（0.3 MPa）下对其进行性能研究。其对无机盐溶液的截留率依次为：Na₂SO₄（91.08%） > MgSO₄（83.42%） > MgCl₂（68.97%） > NaCl（17.62%）;纯水通量可达24.19 L·m^-2·h^-1,较之聚酰胺纳滤膜提高了近60%,且具备良好的稳定性和耐碱性。     

界面聚合聚酰胺纳滤膜渗透选择性能优化的研究进展

纳滤因其分离效率高、操作压力低、环境友好等优点,在废水处理、海水淡化和工业分离纯化等众多领域有着重要的应用。界面聚合法制备的聚酰胺（PA）纳滤膜是最为常用的纳滤膜种类之一。然而界面聚合反应速度快,如何通过调控界面聚合过程,优化纳滤膜选择分离层的结构从而提高渗透选择性,以满足不同领域对纳滤膜需求仍是亟需解决的问题。本文从影响界面聚合单体扩散因素的角度出发,综述了近年来PA纳滤膜渗透选择性能优化的研究进展,包括新型PA纳滤膜、纳米材料/PA混合基质膜及超薄PA纳滤膜3个方面,探讨了选择分离层结构调控与纳滤膜渗透选择性能优化的关系,最后指出目前界面聚合制备高渗透选择性PA纳滤膜在规模化、稳定性及可控性存在的问题,并对未来界面聚合纳滤膜在微观结构和聚合过程调控方面的研究进行了展望。