Preparation And Properties Of The Aromatic Polyamide Separation Membrane

In industrial production and daily life,a large amount of oily wastewater is produced every day.Untreated oil contaminated water will cause serious negative effects on people’s health and ecosystems.The recovery and reuse of oily wastewater can improve the efficiency of water utilization.In recent years,membrane separation technology is considered to be an effective way to separate oil/water mixtures because of its high efficiency,convenient operation,low energy consumption and none secondary pollution.Among them,the ultrafiltration membrane(UF),which has a pore size of 2-100 nm,is intriguing for the separation of oil/water emulsion.Aromatic polyamide is a synthetic fiber with good thermal stability,chemical corrosion resistance and high mechanical performance.This is because the presence of a large number of amide groups in the molecular structure,which has high surface free energy.Aromatic polyamide is considered to be an excellent hydrophilic membrane material.Hydrophilic membrane has good separation effect on oil/water emulsion and also has excellent anti-fouling properties.Therefore,this paper takes the aromatic polyamide as the main raw material by immersionprecipitation phase inversion method and vacuum assisted filtration method to prepare two different oil/water separation membrane,the main research work is performed as follows :(1)A series of hydrophilic PMIA/Ti O2 ultrafiltration membrane was prepared by immersion-precipitation phase inversion method with using the meta-aromatic polyamide(PMIA)polymer as film matrix and hydrophilic Ti O2 as additive.The morphology,chemical composition and crystal structure of PMIA/Ti O2 ultrafiltration membranes were characterized by XRD,ATR-FTIR,SEM and other test methods.the static contact angle of PMIA/Ti O2 ultrafiltration membrane was tested by using the contact angle test instrument.The test results showed that with the increase of Ti O2,the water contact angle of PMIA/Ti O2 ultrafiltration membrane in air decreased,the oil contact angle of PMIA/Ti O2 ultrafiltration membrane under water increased compared with the pure PMIA ultrafiltration membrane.When the TiO2 content is 2.0 wt.%,the water flux reached the maximum value of 168.29L/(m2·h),the retention rate of oil/water emulsion was over 96%,and it had good ability of anti-biofouling pollution.(2)By using the deprotonated dispersion method,the para-aromatic polyamide(PPTA)fiber were dispersed to PPTA nanofiber in the KOH/DMSO solvent system.The length of PPTA nanofiber was 5-10 μm and the diameter of PPTA nanofiber was 20-30 nm.Then,a series of PPTA nanofiber membrane was prepared by using vacuum filtration method.The structure and morphology of PPTA nanofiber separation membranes were characterized by scanning electron microscopy(SEM).The results showed that the pore size and thickness of PPTA nanofiber membrane was nano scale.The pure water flux of PPTA nanofiber membrane was as high as512.19 L/(m2·h).The PPTA nanofiber membrane had stable oleophobic properties under water,the oil contact angle under water was 142°.The separation efficiency of oil/water emulsion was up to 97.8%,which had good oil/water separation efficiency.