Modified Pvdf Membrane Oil-water Separation Performance

Polyvinylidene fluoride membrane(PVDF)membrane has many desirable properties including chemical intertness,favorable mechanical strength and low cost. Howerer,in many cases,the nonspecific protein adsorption on the membrane surface are in the membrane pores due to the inherent hydrophobic characteristics of PVDF often causes serious membrane fouling and thus rapid decline of permeation flux. In order to ensure the wide applications of the PVDF membrane,hydrophilic groups were introduced to PVDF membrane to resist fouling by improving its protein adsorption-resistant property.In this thesis,including PIP and N,N-dimethyl-N(DMAc)were used to modify the PVDF membrane.The effect of the monomer concentration,the polymerizing time,heat - treating time and temperature on the separating performance was initially investigated.The result show that when the concentration of DMAc is 2.5g/L,PIP is 10 g/L,ethylamine is 10 g/L,the separation performance of modified membrane will reach an ideal condition.The FT-IR analysis,gravitational thermal analysis,and contact angle determination were employed to characterize the performance of Polyvinylidene fluoride membrane after hydrophilic modification.The result show that the acyl group is successfully polymerized on the surface of PVDF membrane.,and the contact angle is 35°least than the membrane before modified which implies the hydrophilic performance of the modified membrane is improved a lot.The surface image and cross section of composite membrane was observed by using SEM.In the BSA experiment,after being fouled,the adsorption amount of organic matter of modified membrane is lower than unmodified membrane averagely by 20%.The same result can be drawn from SEM image.PVDF membrane and the modified membrane are washed by pure water,HCL and NaOH solution respectively,the result show that the effect of NaOH is the best and the flux recovery of modified membrane is higher than that of the unmodified membrane.