The Surface Performance For Polyvinylidence Fluoride Membrane Modified By Plasma Treatment

Particles and colloidal substance adsorpted on the surface of the membrane is considered to be one of the main reasons of membrane fouling, the thermodynamic properties of the membrane surface seriously affects the adsorption performance of membrane. This paper use Acid-Base Approach and Extened Young equation calculation of plasma modified membrane and original membrane surface energy parameters, the XDLVO theory was used to quantitative calculate the interfacial free energy of the plasma modified membrane and the original membrane-BSA and MBR pollution, researching the effects of different modification conditions on membrane fouling, and the function of the three kinds of interfacial energy in membrane fouling. Specific experimental conclusions are as follows:(1) Using only plasma modification method, mixed plasma chemical vapor deposition modification method and plasma gas phase graft modification method to modified the original membrane. FT-IR analysis showed that the membrane after plasma modification treatmented, the stretching vibration peak are still exist which produced by PVDF membrane background material. The mixed plasma chemical vapor deposition modified membrane successfully grafted the AA monomer on the surface; Plasma gas phase modified membrane successfully grafted-COOH groups on the surface; SEM image analysis showed that, compared with the original film, after plasma treatment of membrane surface concave and convex structure, roughness increases, the porosity of the membrane surface reduced; Zeta potential of the original and modified membranes are all negative, except only plasma modified membrane, the Zeta potential absolute value of the modified membranes, are larger than the original films,.(2) Using the self-made hollow fiber membrane contact angle measuring device to determine the contact angle of the membrane surface of original and modified membranes in methyl iodide, formamide and water, H2-t have good linear relation, R2 are above 0.99, showing that this technique experiment of selfmade hollow fiber membrane contact angle measuring device can satisfied experiment requirement. The contacts of modified membrane are smaller than the original membranes’ in the three typical solutions.(3) The dispersion force γLW occupied the main part in the composition of the surface tension of original membrane modified membranes, lew is acid force γ +is much smaller than the dispersion force γLW and Louis alkaline forceγ-.The dispersion force γLW of the modified membranes are greater than the original films,, which are between 13-18 mN/m2; the Lewis acid force γ+ are all small and little changed; the Louis alkaline forceγ-are different; All of the membranes,?Gsws TOT are negative, but the only plasma modified membrane and mixed plasma chemical deposited vapor modified membrane are larger than the original films; showing that the only plasma modified membrane and mixed plasma chemical deposited vapor modified membranes, surface hydrophilicity increased.(4) In the film-BSA pollution experiments, the changing rule of the total interfacial energy ?Gmlp TOTis in line with of the ?Gmlp AB, so that the AB forces is the main factor affects the membrane pollution in the BSA solution. The only plasma modified membrane and mixed plasma chemical deposited vapor modified membranes can effectively reduce the pollution of the membrane in adsorption of BSA solution. After water cleaning, membrane flux module response rates are above 69%.(5) In the MBR system, the changing rule of the total interfacial energy ?Gmlp TOTis in line with of the ?Gmlp AB, which behave to promote membrane pollution, AB forces the AB forces is the main factor affects the membrane pollution in the MBR system. In the static adsorption experiment, the ratio of RirfRt? of only plasma modified membrane and mixed plasma chemical deposited vapor modified membranes are much higher than the original films,, the only plasma modified membrane and mixed plasma chemical deposited vapor modified membranes can effectively reduce the membrane adsorption pollution in the MBR reactor. In the long running experiment, the rate of flux attenuation are as fllow: the only plasma modified membrane<mixed plasma chemical deposited vapor modified membranes<plasma gas phase graft modified membrane<the original film. After hydraulic backwash, flux recovery rate of membrane modules are over 55%.(6) The pollution trend of membrane in BSA solution and MBR reactor are consistent with XDLVO theory predicted, showing that the XDLVO theory can be used to predict the membrane pollution trend in different pollutants, selfmade hollow fiber membrane contact angle determination device in this experiment can accurately reflect the change of membrane surface thermodynamic properties before and after modified.