Priority dealcoholization PDMS/PVDF multi-layer compound film and preparation method thereof

Abstract

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.

Description

technical field [0001] The invention relates to a PDMS / PVDF multi-layer composite membrane which can be used for pervaporation preferentially permeating alcohol and a preparation method thereof, belonging to the field of pervaporation membrane separation. Background technique [0002] With the advent of the global energy crisis and environmental crisis, people are forced to seek new energy sources to replace non-renewable energy sources such as petroleum. Among them, alcohol biofuel, as a clean energy source, can not only replace traditional petroleum energy sources, but also greatly reduce pollution of the environment. At present, developed countries such as Europe, America and Japan have replaced part of petroleum with bioethanol to varying degrees, and are committed to large-scale production of bioethanol fuel to solve the energy crisis. [0003] In the process of producing ethanol by biological fermentation, with the increase of ethanol concentration in the fermenter (5...

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Problems solved by technology

"A Pervaporation Separation Membrane for Separating Liquid Mixtures" (US5254251) discloses a preparation method of a double-layer composite membrane. The selection layer is a polyether-polyamide block copolymer, and the reinforcement matrix layer is a silk screen. The matrix strength Higher, selectivity and permeation flux are also greatly improved, but the production cost of polyether-polyamide copolymer is relatively high, which limits its large-scale industrial application

"Method for Separating Ethanol Aqueous Solution Using Polyvinylidene Fluoride Pervaporation Membrane" (CN1239012A) discloses a method of using vinylidene fluoride to prepare a preferential alcohol permeation...