多层聚酰胺复合膜的制备及其特性

PREPARATION AND CHARACTERISTICS OF MULTILAYER POLYAMIDE COMPOSITE MEMBRANES

聚酰胺(PA)具有特定的反渗透(RO)淡化海水和渗透汽化(PV)分离有机物混合物的优良性能。本研究采用水相含单体间苯二胺(m-PDA)和有机相含单体均苯三甲酰氯(TMC)体系,通过多次界面缩聚(IPC)工艺,制成了以RO用的PA复合膜作为多孔支撑膜的多层PA(ML-PA)复合膜。分别用原子力显微镜(AFM)和扫描电子显微镜(SEM)观察了ML-PA膜的微结构。ML-PA膜的厚度、PA高分子微囊聚集的致密程度、平均面粗糙度,都随着IPC反应次数的增加而显著提高。改变制备工艺参数,例如水相中单体和有机相中交联剂的浓度、IPC反应的温度和时间、以及IPC反应的次数,可以得到不同分离性能的ML-PA复合膜。当在m-PDA浓度为2.0%的水溶液中浸渍20min,然后在TMC浓度为0.5%的正己烷溶液中浸渍20s,IPC反应5次,每次反应温度均为40℃,获得的ML-PA复合膜在室温(25℃)下PV分离浓度为88.2%的异丙醇(IPA)水混合物时,渗透通量接近30.0g/m2·h,渗透物中的水含量大于99.0%。

Polyamide （PA） has excellent intrinsic separation characteristics of reverse osmosis （RO） desalination for or separating organic mixtures by pervaporation （PV）. The multilayer polyamide （ML-PA） composite membranes reinforced by asymmetric RO membrane were prepared based on the repeated interracial polycondensation （IPC） oftrimesoyl chloride （TMC） with an aqueous phase containing m-phynylene diamine （m-PDA）. The industrial RO membrane used in the work is thin-film composite （TFC） membrane typically consisted ofa crosslinked aromatic PA formed in situ on the surface of a microporous polysulfone （PS） membrane reinforced by polyester fabric. The microstructures of ML-PA membrane were observed respectively with atom force microscope （AFM） and scanning electron microscope （SEM）. The thickness, denseness of polymer nodules, average surface roughness of ridge-and-valley structure of ML-PA membrane surface distinctly increased with the repeated times of IPC. It was found that ML-PA composite membranes with different characteristics could be prepared when changing the processing conditions like the concentration of the monomers in aqueous and organic phase, the reaction time and the reaction temperature, the repeated times of IPC. The performance of ML-PA composite membrane for separating isopropanol （IPA） （88.2 %）/water mixture by PV was more enhanced. It was concluded from the experimental results, that the permeate flux of 30 g/m^2·h and IPA concentration of over 99 % in permeate could be obtained with ML-PA composite membrane prepared from the optimum conditions.