Research On Filled PPMS Pervaparation Composite Membranes

In this paper,PVDF,PSF and PTFE filters were used as support layer and polyphenyl methyl siloxane(PPMS)as the separation layer.The pervaporation composite membrane was prepared by scraping and coating.The effect of the supported film on the separation of acetone properties of PPMS composite membrane was studied by using pervaporation device and the best support layer was selected.The results showed that the separation performance of PPMS-PVDF composite membrane was better than those of PPMS-PSF composite membrane and PPMS-PTFE composite membrane.A large number of different PPMS composite membranes that using different concentration of PPMS raw material and different filler content were prepared using PVDF as supported layer,PPMS as separating layer,and the hydrophobic fumed silica,activated charcoal and zeolite molecular sieve as the filling agent.The membrane structure and properties were characterized by SEM and swelling experiment,the surface of the composite membrane filled with hydrophobic fumed silica was more smooth than that of zeolite molecular sieve and activated carbon filled,and the dispersion of hydrophobic fumed silica was best.The pervaporation results indicated that the addition of the filler will increase the permeation flux of the composite membrane,and the separation factor will change in a small amplitude.The maximum filling content of different fillers was different in PPMS separation layer,When the filling amount of hydrophobic fumed silica was 10%or zeolite was 10%,the separation effect of composite membrane was better.but separation effect was best for activated carbon when the filling amount was 2%in the composite membrane,because it can fill up to a maximum of 5%.The influences of the conditions on the process of pervaporation are optimized,such as temperature,feed concentration and the downstream pressure of the membrane.The effect of the conditions on the separation performance of the composite membrane was generally similar,such as the higher the temperature,the increase of osmotic flux;the increase of the feed concentration,the increase of the membrane selectivity;the smaller the downstream pressure of the membrane,the greater the permeation flux.Experiments show that the PPMS-PVDF composite membrane filled by hydrophobic fumed silica for the separation of acetone/water mixture performance was best,in condition that the filler content was 10%,the temperature was 40℃,the feed concentration was 10%,the condition of membrane downstream pressure was 0 Kpa,and the final result was that the permeation flux of the composite membrane was 4329.5 g/m~2h and the separation factor was 44.7.