Research On Functional Modification Of PVDF Membrane

For the purpose of this article mainly of PVDF membrane functional modification,two different kinds of modified main methods were stated:adding hydrophilic inorganic particles and hydrophilic modification in the polymer membrane in order to get the Fe₃O₄/PVDF membrane and PVDF-g-PAA ultrafiltration membrane.First of all,the comparison of the PVDF and Fe₃O₄/PVDF membrane,various aspects of the physical properties of membrane were studied,this paper studies the different Fe₃O₄ particles adding quantity to its physical properties change:with Fe₃O₄ particles are added,the cross section of membrane thinning dense layer,hydrophilicity was decreased,mechanical properties were improved;Compared with pure PVDF and Fe₃O₄/PVDF membrane separation performance can be found,adding Fe₃O₄ particles greatly improved its pure water flux;in the case of not adding H₂O₂,catalytic membrane can’t play its role,the removal rate of MB is low,while the pure PVDF membrane despite higher removal rate of MB,but low flux;under the high capacity,intercept down quickly;In the catalytic environment,the removal rate of MB in the catalytic membrane is the same as that of M-0,and the flux is about ten times of M-O.The microstructure before and after the membrane operation was observed.During the test,m-0 had serious membrane fouling,while the membrane with catalyst added had no obvious membrane fouling.Secondly,PVDF-g-PAA ultrafiltration membrane with different acrylic acid doses were prepared by chemical grafting.The microstructure and hydrophilic performance of PVDF-g-PAA were compared under different grafting quantities.Due to the hydrophilicity of the carboxyl group contained by acrylic acid,the internal structure of the membrane changed greatly in the phase separation,and more finger-like holes appeared.With the increase of acrylic acid,the water contact Angle decreased from 91.2° to 27.8°.In addition,the separation performance were systematically studied.With adding more acrylic acid,pure water flux and the rejection of BSA were improved,and found that after alkali treatment of PVDF-g-PAA in flux as well as the rejection of BSA has a certain increase,and for different pH of BSA solution,pH changes had little impact on membrane.By measuring the cyclic performance,PVDF-g-PAA membrane had ideal stability.