Preparation Of Polyvinylidene Fluoride Graft Copolymer Fiber Membrane And Oil-water Separation Study

Membrane separation technology has been used more and more in the treatment of oily wastewater because of its high separation efficiency,environment-friendly operation,small footprint etc.However,the existing polymer membrane materials have the disadvantages of low flux,low fouling resistance and poor mechanical properties,which can not meet the requirements of the actual oily wastewater treatment.It is important to select and develop the high performance separation membranes with high flux,good anti-fouling and mechanical properties.Polyvinylidene fluoride(PVDF)not only has good corrosion resistance,thermal stability and solvent swelling resistance,but also has good mechanical properties,low surface energy and dielectric constant,so in gas separation,membrane distillation,pervaporation,electrochemical and biological medical material has been widely used and studied.In addition,the electrospun nanofiber membrane has many advantages such as adjustable wettability,high specific surface area,high porosity,good connectivity,flexibility and scalability.It has excellent potential applications in environmental applications,especially in oil-water separation.In this study.PVDF is selected as raw material for hydrophilic modification,and through electrospinning to obtain oil-water separation membrane with higyh flux,anti-pollution and good mechanical properties.In this work,polyethylene glycol monomethyl ether(PEGMA)was grafted onto PVDF to prepare PVDF-g-PEGMA graft co-polymer via the ATRP:then electrospinning technology was used to prepare PVDF-g-PEGMA nanofiber membrane;finally through the heat treatment process,the hydrophilic segments of the modified fiber membrane are enriched on the surface to improve the hydrophilic property,so the oil-water separation membrane with super hydrophilic property and good separation performance is prepared(PVDF-g-PEGMA-w).The surface chemical composition of the membranes was analyzed by X-ray photoelectron spectroscopy(XPS).The surface morphology of the membranes was observed by field emission scanning electron microscopy(FESEM).The "cross flow filtration" method was used to evaluate the anti-fouling performance and oil-water separation ability of the membranes,and the separation ability of the "dead end filtration" to the oil-water emulsion was also investigated.The tensile property of the membranes was tested by tensile testing machine and the mechanical properties were evaluated by blasting pressure.The results show that the PVDF-g-PEGMA modified polymer was synthesized successfully via ATRP,through electrospinning and heat treatment technology,super-hydrophilic PVDF-g-PEGMA-w membrane was prepared finally.The modified fiber membrane not only has good separation ability for dispersing oil,but also can achieve more than 99%of the separation efficiency for various emulsified oils.At the same time,the modified membrane also showed high flux,good anti-fouling and excellent mechanical properties.