Preparation Of Poly(Vinylidene Fluoride) Hollow Fiber Ultrafiltration Membrane And Experimental Study Of Membrane Fouling Characteristics

In this paper, poly(vinylidene fluoride) hollow fiber ultrafiltration membrane was investigated.The effects of different additives triethylene glycol(TEG),titanium dioxide(Ti O2),silica(Si O2) on the membrane structure and antifouling properties were studyed.While membrane prepariation conditions as coagulation bath temperature, core temperature liquid,air dry distance on the hollow fiber membrane structure and overall performance.Than discussed the antifouling performance of the membrane to the three different pollutants(BSA,SA,HA).By atomic force microscope(AFM),scanning electron microscope(SEM) X-ray diffraction(XRD) and mechanical strength, permeability and other tests.The main conclusions are as follows:(1) Triethylene glycol(TEG) has good hole making performance As the content of TEG increased,the membrane breaking strength increase,hydrophilicity improved but the rejection rates fall.(2) Ti O2 suppressed the formation of finger macroporous。With the increasing of Ti O2 the menbrane strength is significantly increased, the hydrophilic angle decreases. Ti O2 is helpful to the formation of the cortex,when the Ti O2 content is 3%,the membrane has cortex obviously,retention performance was improved geratly.(3) Silicon dioxide(Si O2) has the thickening property.It can increases the solution viscosity increases, suppress the prolonged finger hole.Si O2 particles are interwoven with PVDF molecular chain in the blend membrane, increasing the number of bonds between the polymer chains,so as to increase the mechanical strength of the film.Si O2 surface There are a certain amount of alcoholic hydroxyl on the surface of Si O2,it can improved the hydrophilic and anti-pollution performance. When the content of Si O2 more than 1% the casting solution is prone to agglomeration, increasing the breaking pore partial in the membrane.(4) Coagulation bath and core liquid temperature can increase the mechanical strength of membrane,while the high temperature also accelerate phase separation process.They are conducive to the formation of finger-like big hole,than the flux increase,but the rejection decrease.So the room temperature is suitable for making membrane. Dry distance has serious affecetion on solution phase.It is diffcult to form film when the Dry distance is shot.While the dry distance large than 10 cm is easy to form a dense skin outside of the membrane,it can also help to improve pollution rejection.(5) Compare the flux decrease,adhesion force and flux recovery rate for BSA,HA,SA of the PVDF/TEG,PVDF/TEG/Ti O2,PVDF/TEG/Si O2 three kinds of blend membrane,the flux decline of PVDF/TEG/Ti O2 membrane is slowly,the adhesion force is small and the flux recovery rate is high respectively.The next is PVDF/TEG/Si O2 membrane,the performance PVDF/TEG membrane is poor.(6) The adhesion force order between pollution and membrane was SA>BSA>HA,the flux decrease order was SA>BSA>HA.The flux decline of pollution had a positive relevant to the adhesion of membrane-foulant. The degree of irreversible pollution order of membrane was BSA> SA > HA,which show the irreversible degree not only has the relevant on adhesion force between pollution and membrane but also the but also to pollutants shape,size and other specific physical and chemical nature.