Preparation And Separation Performance Of Asymmetric PDMS/PVDF Pervaporation Membranes

Traditional industrial separation processes exist separate system complexity, energy consumption is larger, and complex operation, etc. so severely restricted the advances in technology. Generate new membrane separation technology has brought great benefits, which represented pervaporation technology, with its high efficiency, energy saving, environmental protection, low cost, and high selectivity has been widely used in chemical, biological, pharmaceutical and food industries. Advantage of the asymmetric membrane can effectively reduce the membrane thickness, increase flux. Blending is an effective method to improve the membrane properties.This selection of polyvinylidene fluoride, polydimethylsiloxane as the main membrane material, with tetrahydrofuran (THF) and N, N-dimethylacetamide (DMAc) as solvent, prepared the asymmetric PDMS/PVDF blend pervaporation by immersion precipitation phase separation (NIPS).First study the PDMS:PVDF quality ratio on the asymmetric membrane performance; secondly study the effects of evaporation time and coagulation bath composition on membrane performance; The properties of membranes were characterized by coagulation kinetics, SEM, X-ray diffraction, the water contact angle, mechanical strength, thermal gravimetric analysis, etc. Finally, studied the feed concentration and feed temperature on pervaporation properties of asymmetric PDMS/PVDF membranes.Experimental results showed that, when PDMS:PVDF mass ratio was 1:5, and the evaporation time was 70 min at room temperature, coagulation bath composition was DMAc 35 wt%, THF 5 wt% and deionized water 60 wt% system, the membrane has best performance for separation of 15wt% aqueous ethanol solution, the flux was 273.65 g/m2h, separation factor was 9.09.