HPAN/PEI-PDMS有机溶剂纳滤复合膜的制备与性能

Fabrication and performance of HPAN/PEI-PDMS nanofiltration membranes with organic solvent resistace

结合杂化和交联技术,用均苯三甲酰氯(TMC)共价交联的聚乙烯亚胺(PEI)和羟基封端的聚二甲基硅氧烷(PDMS)制备活性层,并以聚丙烯腈(PAN)膜作支撑层,采用界面聚合法制备有机溶剂纳滤复合膜.为增强支撑层与活性层间的界面相互作用,采用NaOH溶液对PAN基膜水解.通过改变NaOH溶液的浓度调控PAN基膜的水解程度,考察不同水解程度对复合膜的物化特性及纳滤性能的影响.通过红外光谱、扫描电镜、静态接触角、拉伸、面积溶胀和溶剂吸附等表征方法,系统研究了复合膜的微观结构和物化特性.以异丙醇、乙酸乙酯、丁酮和正庚烷做溶剂,以聚乙二醇(PEG)作溶质进行复合膜的有机溶剂纳滤实验.结果发现,随着PAN基膜水解度的提高,其表面生成的—COOH量增多,进而会增强复合膜的亲水性,并提高基膜与活性层之间的界面相互作用,增强复合膜的机械稳定性.与水解前相比,基膜水解后所制备的复合膜,其通量和截留率均有提高,同时表现出优越的抗溶胀性能和长时操作稳定性.相比而言,NaOH溶液处理浓度为2.0mol/L时复合膜综合性能最优,其对异丙醇的渗透率达34.6L/(m^2·h·MPa),且保持对PEG1000的较高的截留率(81.8%).

A series of composite nanofiltration membranes with organic solvent resistace were fabricated by combining of the hybridization and cross-linking techniques.Polyethyleneimine（PEI）and hydroxyl terminated trifluoride polydimethylsiloxane（PDMS）were covalently cross-linked with trimesoyl chloride（TMC）through interfacial polymerization to generate the active layer on the top of polyacrylonitrile（PAN）ultrafiltration membrane.For enhancing the interfacial compatibility between support layer and active layer,PAN was hydrolyzed by sodium hydroxide prior to the polymerization.The hydrolysis degree of the HPAN support was adjusted by NaOH concentration,and the influences of hydrolysis degree on the physico-chemical properties and nanofiltration performances of the composite membrane were investigated in detail.The composite membranes were tested via Fourier transform infrared spectroscopy,scanning electron microscope,static contact angle measurement,tensile testing,area swelling,and solvent uptake.The nanofiltration experiment of the composite membrane was carried out using n-heptane,butanone,ethyl acetate,and isopropanol as organic solvents,as well as polyethylene glycol 1000 as solute.It was found that with the increase of hydrolysis degree,the—COOH amount on HPAN support layer increased,which would improve the membrane hydrophilcity and strengthen the interfacial interactions.Consequently,the mechanical stability of the composite membrane was enhanced.The hydrolysis of the PAN support elevated the solvent flux and rejection of the composite membrane,and meanwhile attained excellent solvent resistance and potential long-term operation stability.In particular, when the concentration of NaOH was 2.0mol/L,the composite membrane had the acceptable solvent permeance for isopropanol[up to 34.6L/（m^2·h·MPa）]and remained the high rejection for PEG 1000（up to 81.8%）.