A composite pervaporation membrane doped with a hydrophobic modified material and its preparation and application

Abstract

The invention discloses a composite pervaporation membrane doped with a hydrophobic modified material and preparation and application thereof. The preparation method comprises: treatment of a PVDF base film, synthesis of layered polyaniline, hydrophobic modification of the polyaniline, and preparation of the composite pervaporation membrane doped with a hydrophobic modified material. The preparation process of the invention is simple and easy to operate. The prepared composite pervaporation membrane doped with a hydrophobic modified material can be applied to pervaporation separation of organic matter / water. Since the polyaniline itself has extremely high hydrophobicity, the surface of the PDMS membrane becomes more hydrophobic. Moreover, the polyaniline synthesized by this method is in a multilayered sheet shape, providing an additional channel for the transportation of alcohols.

Description

Technical Field

[0001] The invention belongs to the technical field of functional membrane preparation and separation application, and specifically relates to a composite pervaporation membrane doped with a hydrophobic modified material and the preparation and application thereof. Background Art

[0002] Pervaporation is a membrane-based separation technology that offers competitive advantages over conventional separation technologies such as distillation and absorption for separation of azeotropic mixtures, heat-sensitive compounds and organic-organic mixtures, and removal of dilute organic compounds from wastewater. The process requires the feed liquid mixture to contact one side of a semipermeable membrane, while vacuum or sweep gas is applied to the permeate side of the membrane to generate a chemical potential difference, allowing the separation to occur. The separation mechanism of the pervaporation process mainly relies on the preferential adsorption and diffusion of the target component through the membrane. Therefore, it is not limited by thermodynamic vapor-liquid equilibrium. Compared to conventional separation technologies, pervaporation inherits the advantages of membrane separation technology such as small footprint, simplicity and flexibility. In addition, since only latent heat of evaporation is required for separation, it is believed to have low energy consumption.

[0003] At present, the pervaporation membrane separation technology has achieved large-scale industrial application in the removal of small amounts of water from organic solvents at home and abroad. However, it is still in the primary application stage for the removal or recovery of low-concentration organic matter from water. Among various biofuels, n-butanol is considered to be a promising biofuel due to its low volatility, low corrosiveness, high calorific value and good compatibility with petroleum. At present, the fermentation process is the most commonly used method for producing n-butanol. However, the n-butanol produced during the fermentation process is toxic to microorganisms that inhibit fermentation, resulting in a low concentration of n-butanol product. Therefore, the use of pervaporation technology to separate low-concentration butanol from water has become a topic of concern for many researchers. In the research process, organic-inorganic hybrid membranes were gradually discovered to make up for the defects of pure organic membranes or inorganic membranes.

[0004] It is well known that the performance of membrane materials is a key factor in determining the comprehensive performance of pervaporation. Polydimethylsiloxane (PDMS) is the benchmark material for alcohol permeation selective membranes and has been widely studied by many researchers. However, the separation coefficient of pure PDMS membranes is relatively low, and the trade-off between flux and selectivity limits its application in industry. Therefore, in order to further improve the separation performance of PDMS membranes, filling with hydrophobic materials has gradually become a research hotspot. Summary of the invention

[0005] In order to overcome the problem of low separation coefficient in the existing PDMS-based pervaporation membrane, the present invention provides a composite pervaporation membrane doped with a hydrophobic modified material and the preparation and application thereof.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a composite pervaporation membrane doped with a hydrophobic modified material comprises the following steps:

[0008] (1) Treatment of PVDF base film

[0009] Soak the PVDF base film in a mixed solution of ethanol / water for 3-6 hours, then take it out, rinse it with deionized water, dry it (60°C, 5-10 hours), and place it in deionized water for later use;

[0010] The molecular weight cut-off of the PVDF bottom membrane is 50,000;

[0011] In the ethanol / water mixed solution, the mass ratio of ethanol / water is 1:1;

[0012] (2) Synthesis of layered polyaniline

[0013] Aniline is added to hydrochloric acid, stirred and mixed, and the mixture is recorded as solution A for later use; ammonium persulfate is added to deionized water, stirred and dissolved, and the mixture is recorded as solution B for later use; after solution A and solution B are cooled to 0-5°C respectively, solution B is poured into solution A, the temperature is maintained between 0-5°C, and the mixture is allowed to react for 1 hour, and then filtered, washed (with water and methanol until colorless), and dried (80°C, 12-24 hours) to obtain layered polyaniline powder-doped state; the obtained layered polyaniline powder-doped state is added to 5wt% ammonia solution, stirred for 24 hours, and then filtered, washed (with water and methanol until colorless), and dried (80°C, 12-24 hours) to obtain layered polyaniline powder-intermediate state;

[0014] The aniline is high-quality aniline that has been distilled; the molar ratio of aniline to ammonium persulfate is 1:1; preferably, the temperature at which aniline and ammonium persulfate are mixed is 0-2°C;

[0015] In the solution A, the concentration of aniline is 0.04-0.5M, and the concentration of hydrochloric acid is 1M;

[0016] The "solution A" and "solution B" have no special meanings, and are marked as "A" and "B" only to distinguish the solutions prepared in different operation steps;

[0017] (3) Hydrophobic modification of polyaniline

[0018] Adding layered polyaniline powder-intermediate state and organic macromolecular acid into deionized water, stirring and reacting for 12 hours, then filtering, washing (washing with water and methanol until colorless), and drying (80°C, 12-24 hours) to obtain layered polyaniline powder-acid doping; preparing a mixed solution of silane coupling agent and n-heptane, adding layered polyaniline powder-acid doping, stirring and reacting for 8 hours, then filtering, washing (washing with n-heptane until colorless), and drying (80°C, 12-24 hours) to obtain modified layered polyaniline powder;

[0019] The mass ratio of the layered polyaniline powder-intermediate state to the organic macromolecular acid is 1-16:1;

[0020] The organic macromolecular acid is selected from citric acid, malic acid, etc.;

[0021] The silane coupling agent is selected from KH550, KH560, KH590, etc.; the concentration of the silane coupling agent in n-heptane is 1-5wt%; the mass ratio of the layered polyaniline powder-acid doping to the silane coupling agent is 1-20:1;

[0022] (4) Preparation of composite pervaporation membrane doped with hydrophobic modified materials

[0023] Add PDMS to n-heptane, stir at room temperature for 30 minutes, add modified layered polyaniline powder, and stir for 30 minutes; then repeat the stirring for 30 minutes and ultrasonic treatment for 30 minutes for 3 hours; then add a crosslinking agent, stir for 15 minutes, add a catalyst, stir for 30 minutes, ultrasonic treatment for 10 minutes, let stand for 10-30 minutes, and then use a spin coating method to form a membrane on the PVDF base membrane prepared in step (1), and dry in an oven at 80°C for 12 hours to obtain the composite pervaporation membrane doped with the hydrophobic modified material;

[0024] The viscosity of the PDMS at 25° C. is 50,000 cst; the mass ratio of PDMS to n-heptane is 1-2:10; the mass ratio of PDMS to the crosslinking agent and the catalyst is 10-20:1:0.1; the amount of the modified layered polyaniline powder is 1-15wt% of the mass of the PDMS;

[0025] The crosslinking agent is selected from any one of ethyl orthosilicate, 3-methacryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, and phenyltriethoxysilane;

[0026] The catalyst is dibutyltin dilaurate.

[0027] The invention relates to a composite pervaporation membrane doped with a hydrophobic modified material obtained by the preparation method.

[0028] The present invention also relates to the application of the composite pervaporation membrane doped with the hydrophobic modified material in the pervaporation separation of organic matter / water; the organic matter is butanol, ethanol, methanol, specifically, for example: 1wt% butanol / water.

[0029] The relevant technical principles in the present invention are as follows:

[0030] The polyaniline in the present invention is a multilayer sheet structure, which is prepared by using a specific molar ratio of aniline to an oxidant and a specific reaction time and temperature in a hydrochloric acid system. This sheet structure plays a good role in promoting the separation of alcohol / water in a PDMS-based pervaporation membrane.

[0031] Silane coupling agent is used for secondary modification of polyaniline. The initially synthesized polyaniline sheet material can effectively improve the selectivity and permeability of alcohol / water of the pervaporation membrane, but it is easy to agglomerate in the polymer matrix, the mixing is uneven, and there is an upper limit to its loading (compatibility problem). In order to solve this uneven phenomenon, very complicated mixing treatment experimental steps are required in the process of preparing the membrane. In order to simplify the experimental process, secondary doping is carried out on polyaniline to improve the dispersibility of the polyaniline material. After the secondary doping of polyaniline, the dispersibility and hydrophobicity of polyaniline are enhanced, but some groups (such as hydroxyl groups) present in some doping molecules are not conducive to the cross-linking process of PDMS, so silane coupling agent is used for secondary modification, and the compatibility of the material with the PDMS matrix is ​​enhanced at the same time. In the selection of silane coupling agent, under the condition of giving priority to performance, amino silane coupling agent (such as KH550) and epoxy silane coupling agent (such as KH590) are preferred.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The preparation process is simple and easy to operate.

[0034] (2) Since polyaniline itself has extremely high hydrophobicity, the surface of the PDMS membrane becomes more hydrophobic; on the other hand, the polyaniline synthesized by this method is in the form of multilayer sheets, providing additional channels for the transport of alcohols. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Without departing from the content and scope of the present invention, changes in implementation should be included in the technical scope of the present invention.

[0036] Embodiment 1:

[0037] (1) Treatment of PVDF bottom membrane: Soak the PVDF bottom membrane with a molecular weight cutoff of 50,000 in a mixed solution of 50 wt% ethanol / water for 4 h, then take it out and rinse it with deionized water, dry it in an oven at 60°C for 8 h, and then place it in deionized water for use.

[0038] (2) Synthesis of layered polyaniline: Add a certain amount of hydrochloric acid to 100 ml of deionized water (prepare 1M concentration), stir to mix evenly, then add an appropriate amount of aniline (0.1M), stir for 20-40 minutes to mix evenly, record as solution A, and set aside. Take an appropriate amount of ammonium persulfate and add it to 100 ml of deionized water (0.1M), stir for 20-40 minutes to dissolve and mix evenly, record as solution B, and set aside. After solution A and solution B are cooled to 0-5°C respectively, quickly pour solution B into solution A. Keep the temperature range between 0-5°C and let the reaction stand for 1 hour. After the reaction is completed, filter, wash with water and methanol until colorless, and dry in an oven at 80°C for 12 hours to obtain layered polyaniline powder-doped state. The layered polyaniline powder-doped state was then added to an excess of 5wt% ammonia solution, stirred for 24 hours, filtered, washed with water and methanol until colorless, and dried in an oven at 80°C for 12 hours to obtain the layered polyaniline powder-intermediate state.

[0039] (3) Hydrophobic modification of polyaniline: 5wt% of layered polyaniline powder-intermediate state and 1wt% of citric acid were added to 100ml of deionized water, stirred for reaction for 12h, filtered, washed with water and methanol until colorless, and dried in an oven at 80℃ for 12h to obtain layered polyaniline powder-acid doping. Then, a mixed solution of 2wt% of silane coupling agent and n-heptane was prepared, stirred evenly, and then 5wt% of layered polyaniline powder-acid doping was added, stirred for reaction for 8h, filtered, washed with n-heptane until colorless, and dried in an oven at 80℃ for 12h to obtain modified layered polyaniline powder.

[0040] (4) Preparation of composite pervaporation membrane doped with hydrophobic modified material: 0.684 g PDMS was added to 5 mL n-heptane, stirred at room temperature for 30 min, then 5 wt% modified layered polyaniline powder by weight of PDMS was added and stirred for 30 min; then the steps of stirring for 30 min and ultrasonicating for 30 min were repeated for 3 h; then 80 μL of cross-linking agent tetraethyl orthosilicate was added and stirred for 15 min, 8 μL of catalyst dibutyltin dilaurate was added and stirred for 30 min, ultrasonicated for 10 min, and after standing for 10-30 min, a membrane was prepared on the above PVDF membrane by spin coating, and the thickness of the separation layer was controlled between 5 μm and 10 μm. The membrane was dried in an oven at 80°C for 12 h to obtain a composite pervaporation membrane doped with hydrophobic modified material.

[0041] The permeation flux of the obtained composite pervaporation membrane doped with hydrophobic modified materials at 70°C and 1 wt% butanol / water was 2053 g / m 2 h, the separation factor is 40.

[0042] Embodiment 2:

[0043] (1) Treatment of PVDF bottom membrane: Soak the PVDF bottom membrane with a molecular weight cutoff of 50,000 in a mixed solution of 50 wt% ethanol / water for 4 h, then take it out and rinse it with deionized water, dry it in an oven at 60°C for 8 h, and then place it in deionized water for use.

[0044] (2) Synthesis of layered polyaniline: Add a certain amount of hydrochloric acid to 100 ml of deionized water (prepare 1M concentration), stir to mix evenly, then add an appropriate amount of aniline (0.1M), stir for 20-40 minutes to mix evenly, record as solution A, and set aside. Take an appropriate amount of ammonium persulfate and add it to 100 ml of deionized water (0.1M), stir for 20-40 minutes to dissolve and mix evenly, record as solution B, and set aside. After solution A and solution B are cooled to 0-5°C respectively, quickly pour solution B into solution A. Keep the temperature range between 0-5°C and let the reaction stand for 1 hour. After the reaction is completed, filter, wash with water and methanol until colorless, and dry in an oven at 80°C for 12 hours to obtain layered polyaniline powder-doped state. The layered polyaniline powder-doped state was then added to an excess of 5wt% ammonia solution, stirred for 24 hours, filtered, washed with water and methanol until colorless, and dried in an oven at 80°C for 12 hours to obtain the layered polyaniline powder-intermediate state.

[0045] (3) Hydrophobic modification of polyaniline: 5wt% of layered polyaniline powder-intermediate state and 1wt% of citric acid were added to 100ml of deionized water, stirred for reaction for 12h, filtered, washed with water and methanol until colorless, and dried in an oven at 80℃ for 12h to obtain layered polyaniline powder-acid doping. Then, a mixed solution of 2wt% of silane coupling agent and n-heptane was prepared, stirred evenly, and then 5wt% of layered polyaniline powder-acid doping was added, stirred for reaction for 8h, filtered, washed with n-heptane until colorless, and dried in an oven at 80℃ for 12h to obtain modified layered polyaniline powder.

[0046] (4) Preparation of composite pervaporation membrane doped with hydrophobic modified material: 0.684 g PDMS was added to 5 mL n-heptane, stirred at room temperature for 30 min, then modified layered polyaniline powder with a mass content of 10 wt% of PDMS was added and stirred for 30 min; then the steps of stirring for 30 min and ultrasonicating for 30 min were repeated for 3 h; then 80 μL of cross-linking agent 3-methacryloxypropylmethyldimethoxysilane was added and stirred for 15 min, 8 μL of catalyst dibutyltin dilaurate was added and stirred for 30 min, ultrasonicated for 10 min, and after standing for 10-30 min, a membrane was prepared on the above PVDF membrane by spin coating, and the thickness of the separation layer was controlled between 5 μm and 10 μm. The membrane was dried in an oven at 80°C for 12 h to obtain a composite pervaporation membrane doped with hydrophobic modified material.

[0047] The permeation flux of the obtained composite pervaporation membrane doped with hydrophobic modified materials at 70°C and 1 wt% butanol / water was 2143 g / m2 h, the separation factor is 43.

[0048] Embodiment 3:

[0049] (1) Treatment of PVDF bottom membrane: Soak the PVDF bottom membrane with a molecular weight cutoff of 50,000 in a mixed solution of 50 wt% ethanol / water for 4 h, then take it out and rinse it with deionized water, dry it in an oven at 60°C for 8 h, and then place it in deionized water for use.

[0050] (2) Synthesis of layered polyaniline: Add a certain amount of hydrochloric acid to 100 ml of deionized water (prepare 1M concentration), stir to mix evenly, then add an appropriate amount of aniline (0.1M), stir for 20-40 minutes to mix evenly, record as solution A, and set aside. Take an appropriate amount of ammonium persulfate and add it to 100 ml of deionized water (0.1M), stir for 20-40 minutes to dissolve and mix evenly, record as solution B, and set aside. After solution A and solution B are cooled to 0-5°C respectively, quickly pour solution B into solution A. Keep the temperature range between 0-5°C and let the reaction stand for 1 hour. After the reaction is completed, filter, wash with water and methanol until colorless, and dry in an oven at 80°C for 12 hours to obtain layered polyaniline powder-doped state. The layered polyaniline powder-doped state was then added to an excess of 5wt% ammonia solution, stirred for 24 hours, filtered, washed with water and methanol until colorless, and dried in an oven at 80°C for 12 hours to obtain the layered polyaniline powder-intermediate state.

[0051] (3) Hydrophobic modification of polyaniline: 5wt% of layered polyaniline powder-intermediate state and 1wt% of citric acid were added to 100ml of deionized water, stirred for reaction for 12h, filtered, washed with water and methanol until colorless, and dried in an oven at 80℃ for 12h to obtain layered polyaniline powder-acid doping. Then, a mixed solution of 2wt% of silane coupling agent and n-heptane was prepared, stirred evenly, and then 10wt% of layered polyaniline powder-acid doping was added, stirred for reaction for 8h, filtered, washed with n-heptane until colorless, and dried in an oven at 80℃ for 12h to obtain modified layered polyaniline powder.

[0052] (4) Preparation of composite pervaporation membrane doped with hydrophobic modified material: 0.684 g PDMS was added to 5 mL n-heptane, stirred at room temperature for 30 min, then 5 wt% modified layered polyaniline powder by weight of PDMS was added and stirred for 30 min; then the steps of stirring for 30 min and ultrasonicating for 30 min were repeated for 3 h; then 80 μL of cross-linking agent vinyltrimethoxysilane was added and stirred for 15 min, 8 μL of catalyst dibutyltin dilaurate was added and stirred for 30 min, ultrasonicated for 10 min, and after standing for 10-30 min, a membrane was prepared on the above PVDF membrane by spin coating, and the thickness of the separation layer was controlled between 5 μm and 10 μm. The membrane was dried in an oven at 80°C for 12 h to obtain a composite pervaporation membrane doped with hydrophobic modified material.

[0053] The permeation flux of the obtained composite pervaporation membrane doped with hydrophobic modified materials at 70°C and 1 wt% butanol / water was 2213 g / m 2 h, the separation factor is 36.

[0054] Embodiment 4:

[0055] (1) Treatment of PVDF bottom membrane: Soak the PVDF bottom membrane with a molecular weight cutoff of 50,000 in a mixed solution of 50 wt% ethanol / water for 4 h, then take it out and rinse it with deionized water, dry it in an oven at 60°C for 8 h, and then place it in deionized water for use.

[0056] (2) Synthesis of layered polyaniline: Add a certain amount of hydrochloric acid to 100 ml of deionized water (prepare 1M concentration), stir to mix evenly, then add an appropriate amount of aniline (0.1M), stir for 20-40 minutes to mix evenly, record as solution A, and set aside. Take an appropriate amount of ammonium persulfate and add it to 100 ml of deionized water (0.1M), stir for 20-40 minutes to dissolve and mix evenly, record as solution B, and set aside. After solution A and solution B are cooled to 0-5°C respectively, quickly pour solution B into solution A. Keep the temperature range between 0-5°C and let the reaction stand for 1 hour. After the reaction is completed, filter, wash with water and methanol until colorless, and dry in an oven at 80°C for 12 hours to obtain layered polyaniline powder-doped state. The layered polyaniline powder-doped state was then added to an excess of 5wt% ammonia solution, stirred for 24 hours, filtered, washed with water and methanol until colorless, and dried in an oven at 80°C for 12 hours to obtain the layered polyaniline powder-intermediate state.

[0057] (3) Hydrophobic modification of polyaniline: 5wt% of layered polyaniline powder-intermediate state and 1wt% of citric acid were added to 100ml of deionized water, stirred for reaction for 12h, filtered, washed with water and methanol until colorless, and dried in an oven at 80℃ for 12h to obtain layered polyaniline powder-acid doping. Then, a mixed solution of 2wt% of silane coupling agent and n-heptane was prepared, stirred evenly, and then 5wt% of layered polyaniline powder-acid doping was added, stirred for reaction for 8h, filtered, washed with n-heptane until colorless, and dried in an oven at 80℃ for 12h to obtain modified layered polyaniline powder.

[0058] (4) Preparation of composite pervaporation membrane doped with hydrophobic modified material: 0.684 g PDMS was added to 5 mL n-heptane, stirred at room temperature for 30 min, then modified layered polyaniline powder with a mass content of 15 wt% of PDMS was added and stirred for 30 min; then the steps of stirring for 30 min and ultrasonicating for 30 min were repeated for 3 h; then 80 μL of cross-linking agent phenyltriethoxysilane was added and stirred for 15 min, 8 μL of catalyst dibutyltin dilaurate was added and stirred for 30 min, ultrasonicated for 10 min, and after standing for 10-30 min, a membrane was prepared on the above PVDF membrane by spin coating, and the thickness of the separation layer was controlled between 5 μm and 10 μm. The membrane was dried in an oven at 80°C for 12 h to obtain a composite pervaporation membrane doped with hydrophobic modified material.

[0059] The permeation flux of the obtained composite pervaporation membrane doped with hydrophobic modified materials at 70°C and 1 wt% butanol / water was 1089 g / m 2 h, the separation factor is 45.

Claims

1. A method for preparing a composite pervaporation membrane doped with a hydrophobic modified material, characterized in that: The steps include: (1) Treatment of PVDF base film Soak the PVDF base film in a mixed solution of ethanol / water for 3-6 hours, then take it out, rinse it with deionized water, dry it, and place it in deionized water for later use; (2) Synthesis of layered polyaniline Add aniline to hydrochloric acid, stir and mix, record as solution A, and set aside; add ammonium persulfate to deionized water, stir and dissolve, record as solution B, and set aside; after solution A and solution B are cooled to 0-5°C respectively, solution B is poured into solution A, the temperature is maintained between 0-5°C, and the reaction is allowed to stand for 1 hour, then filtered, washed, and dried to obtain layered polyaniline powder-doped state; the obtained layered polyaniline powder-doped state is added to 5wt% ammonia solution, stirred for 24 hours, then filtered, washed, and dried to obtain layered polyaniline powder-intermediate state; (3) Hydrophobic modification of polyaniline Adding layered polyaniline powder-intermediate state and organic macromolecular acid into deionized water, stirring and reacting for 12 hours, then filtering, washing, and drying to obtain layered polyaniline powder-acid doping; preparing a mixed solution of silane coupling agent and n-heptane, adding layered polyaniline powder-acid doping, stirring and reacting for 8 hours, then filtering, washing, and drying to obtain modified layered polyaniline powder; The organic macromolecular acid is selected from one or more of citric acid and malic acid; The silane coupling agent is selected from one or more of KH550, KH560, and KH590; (4) Preparation of composite pervaporation membrane doped with hydrophobic modified materials Add PDMS to n-heptane, stir at room temperature for 30 minutes, add modified layered polyaniline powder, and stir for 30 minutes; then repeat the stirring for 30 minutes and ultrasonic treatment for 30 minutes for 3 hours; then add a crosslinking agent, stir for 15 minutes, add a catalyst, stir for 30 minutes, ultrasonic treatment for 10 minutes, let stand for 10-30 minutes, and then use a spin coating method to form a membrane on the PVDF base membrane prepared in step (1), and dry in an oven at 80°C for 12 hours to obtain the composite pervaporation membrane doped with the hydrophobic modified material; The crosslinking agent is selected from any one of ethyl orthosilicate, 3-methacryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, and phenyltriethoxysilane; The catalyst is dibutyltin dilaurate.

2. The method for preparing a composite pervaporation membrane doped with a hydrophobic modified material according to claim 1, characterized in that: In step (1), the molecular weight cutoff of the PVDF bottom membrane is 50,000.

3. The method for preparing a composite pervaporation membrane doped with a hydrophobic modified material according to claim 1, characterized in that: In step (2), the molar ratio of aniline to ammonium persulfate is 1:

1.

4. The method for preparing a composite pervaporation membrane doped with a hydrophobic modified material according to claim 1, characterized in that: In step (3), the mass ratio of the layered polyaniline powder-intermediate state to the organic macromolecular acid is 1-16:

1.

5. The method for preparing a composite pervaporation membrane doped with a hydrophobic modified material according to claim 1, characterized in that: In step (3), the mass ratio of the layered polyaniline powder-acid doping to the silane coupling agent is 1-20:

1.

6. The method for preparing a composite pervaporation membrane doped with a hydrophobic modified material according to claim 1, characterized in that: In step (4), the viscosity of the PDMS at 25° C. is 50,000 cst.

7. The method for preparing a composite pervaporation membrane doped with a hydrophobic modified material according to claim 1, characterized in that: In step (4), the mass ratio of PDMS to the cross-linking agent and the catalyst is 10-20:1:0.

1.

8. The method for preparing a composite pervaporation membrane doped with a hydrophobic modified material according to claim 1, characterized in that: In step (4), the amount of modified layered polyaniline powder used is 1-15 wt % of the mass of PDMS.

9. A composite pervaporation membrane doped with a hydrophobic modified material obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the composite pervaporation membrane doped with a hydrophobic modified material as claimed in claim 9 in pervaporation separation of organic matter / water, characterized in that: The organic matter is butanol, ethanol or methanol.