Study Of Plasma Modified Ultrafiltration Membrane With External Magnetic Field

This paper mainly studied the synergistic effect of non-uniform magnetic field on plasma modified polysulfone ultrafiltration membrane.A magnetic field was additionally set up outside the plasma apparatus to determine the hydrophilicity and antifouling properties of the polysulfone membrane under different magnetic field strengths,magnetic field positions,discharge times,powers,and pressures of the reaction chamber.Using the combination of spectroscopic method and probe method,real-time diagnosis of plasma performance parameters in the modification process,such as electron temperature,electron density and other characteristic parameters,and data analysis.Further study of the mechanism of RF plasma modified ultrafiltration membrane under external magnetic field provided theoretical support for plasma modified ultrafiltration membrane.The optimal conditions for plasma modification with external magnetic field are 80W,120s,20Pa plus 3 permanent magnets 15cm away from the discharge center.The contact angle of the polysulfone membrane was reduced from the original membrane by 80°after plasma to 43°,and the magnetic field was further reduced to 30°after the plasma modification.Improve the surface polarity of the polymer film material,improve its wettability,the treatment effect is obvious,and the surface hydrophilicity increases.The membrane flux was measured in the presence or absence of a magnetic field.The amount of pure water in the original membrane was 19.25 L/（m²·min）,the contamination rate was 54%,the flux attenuation rate was 65%,and the rejection rate was 71%.Compared with the plasma,the magnetic field synergistic plasma modification improves the pure water flux from 23.65 L/（m²·min）to 30.00 L/（m²·min）;the pollution rate drops from 35%to 28%;the flux decay rate From 33%to 28%;rejection from 83%to 94%.The performance of the modified polysulfone membrane was improved,and the effect was better when the magnetic field was applied.The performance of the modified polysulfone membrane was improved,and the effect was better when the magnetic field was applied.The surface of the polysulfone membrane before and after the modification was analyzed by SEM.After being modified by plasma,the surface etched at a distance of 15 cm from the discharge center was very high.The surface structure of the membrane was destroyed,and the distance from the discharge center increased,and the etching was weakened,after further weakened by external magnetic field.During the discharge process,the ions mainly consist of N_I,N_II,N_III,N_IV and N_V.The characteristic peaks are all concentrated in the 330-440 nm band.Under the optimal conditions,the electron temperature is 1.92×10⁴K.The electron density is 2.90×10¹⁵ m^-3.At this time,nitrogen radicals are the main components in the modification process,and the activity is moderate,and the etching phenomenon is weak.This provides the possibility of generating amino groups on the polymer surface.