The invention relates to an
ethanol-permselective PDMS / PVDF multilayered
composite membrane and the preparation method, which belongs to a
pervaporation membrane separation field. The multilayered
composite membrane is made based on the following processes: firstly, the PVDF porous
basal membrane is prepared by a two-faced wiped film of kynoar polyvinylindene
fluoride (PVDF) solution on the
polyester non-
woven fabric support layer using submersion and
sedimentation transformation method; secondly, the membrane liquid, which contains dimethyl
silicone polymer (PDMS), cross linking agent and catalyst, is prepared, and the PVDF porous
basal membrane is immersed in the membrane liquid for 10s-1min. Each of two sides of the PVDF
basal membrane are coated with a layer of
silicone base by using immersion and painting method, and then the PVDF basal membrane is dried and cross linked, and so the multilayered
composite membrane is made. The existing pure PDMS membrane has bad separability to
ethanol aqueous solution, and the highest
separation factor is 10.8 ([EtOH] equals to 8wt percent, 30 DGE C). The multilayered symmetrical composite membrane made of the invention has an excellent
ethanol-permselective property to low concentration ethanol
aqueous solution (5wt percent-30wt percent), and for the ethanol
aqueous solution which has a concentration of 5wt percent, the
separation factor ¿” value equals to 15, and the
permeation flux J equals to 450g / m2h, under the temperature of 60 DGE C.