Functionalized Multi-walled Carbon Nanotube Modified PVDF Membrane And Its Oil-water Separation Performance

A great deal of oily wastewater is produced by industrial processing,owing to the shortage of water resources and water pollution which is becoming more and more serious,recycling of water resources has gained great importance.At present,there are several methods for the purification of oily wastewater,including adsorption,separation and evaporation.Among these methods,the membrane separation technology has been regarded as the key method to solve the water crisis owing to its high oil-removal efficiency,low cost,compact design,and so on.Recently,polyvinylidene fluoride(PVDF)membrane has been widely used in fabricating ultrafiltration membrane for its good mechanical properties as well as high thermal and chemical stability.However,PVDF membrane is easily fouled for its intrinsic hydrophobicity.Thus,how to enhance the hydrophilicity of PVDF membrane gains special attention.PVDF membrane modification methods can be divided into two types of membrane materials and membrane surface modification,membrane surface modification method depends on with the polar groups on the membrane surface modification,including surface grafting method and surface coating method.Membrane material modification is devoted to adding polar groups in polymer matrix to improve the hydrophilicity of membrane.Therefore,this paper decided to modify the membrane with different membrane modification methods and explore the separation properties of the modified membrane.A novel hydrophilic PVDF composite membrane functionalized by ZrO2-MWCNTs hybrid was demonstrated by a simple phase-inversion method.For this purpose,ZrO2 nanoparticles were firstly loaded on the surface of MWCNTs via hydrothermal route.The successful loading of ZrO2,which can be confirmed by X-ray diffractometer(XRD),Fourier transform infrared spectrometer(FT-IR)and thermogravimetric analyzer(TGA).The membrane structure was studied by scanning electron microscope(SEM)and atomic force microscope(AFM),it is proved that Binary metal oxide can improve the dispersibility of multi-walled carbon nanotubes,on the other hand,it can provide more adsorption sites for membrane pore channels and improve the oil and water separation ability.Firstly,synthesis of A-MWCNTs nanocomposites with high hydrophilicity,FT-IR,TEM and XPS were performed to investigate the APTES modified MWCNTs,These results indicate the formation of covalent bonds between MWCNTs and APTES.For exhibiting the advantages directly and effectively is still a potential problem.In this research,different from traditional modification method,we prepared PVDF membranes by phase inversion method and then embedded APTES functionalized MWCNTs(A-MWCNTs)on the surface of PVDF membranes under pressure.By leica microscope and the total organic carbon analyzer(TOC)determined found membranes for the different types of oil-water emulsion also has a high separation efficiency,but due to the unstable embedded in the surface of carbon nanotubes and easy blocking channel,we consider a more convenient method of surface modification.A novel superhydrophilic and under-water superoleophobic PVDF membrane was successfully fabricated by simple modification with dopamine and APTES functionalized A-MWCNTs,the A-MWCNTs were successfully anchored on the PVDF membrane surface.Besides,the as-prepared membranes can selectively separate water from kinds of oil-in-water emulsions with high water permeation flux and outstanding separation efficiency,More importantly,theses membranes also showed excellent recyclability and anti-fouling performance.In a word,the modified membranes prepared by different membrane modification methods all can improve the oil and water separation performance significantly.