阅读说明：本技术 一种优先透醇的SiO2/PVDF杂化膜的制备方法 (SiO with preferential alcohol permeability2Preparation method of PVDF hybrid membrane ) 是由 穆效平 于 2020-05-30 设计创作，主要内容包括：本发明提供了一种优先透醇的SiO<Sub>2</Sub>/PVDF杂化膜的制备方法,将二氧化硅实心颗粒和二氧化硅介孔颗粒混合后经硅烷偶联剂疏水改性后添加至PVDF铸膜液中进行相转化从而制得优先透醇的SiO<Sub>2</Sub>/PVDF杂化膜。本发明所制备的膜相对于单一采用二氧化硅纳米实心颗粒或二氧化硅介孔颗粒的膜来说,通量增幅达50%以上。(The invention provides SiO with preferential alcohol permeability 2 The preparation method of the PVDF hybrid membrane comprises the steps of mixing solid silicon dioxide particles and mesoporous silicon dioxide particles, performing hydrophobic modification by a silane coupling agent, adding the mixture into a PVDF membrane casting solution for phase transformation to prepare SiO with alcohol penetration priority 2 PVDF hybrid membranes. Compared with the membrane which singly adopts the silica nano solid particles or the silica mesoporous particles, the membrane prepared by the invention has the flux amplification of more than 50 percent.)

1. SiO with preferential alcohol permeability₂The preparation method of the PVDF hybrid membrane is characterized in that solid silicon dioxide particles and mesoporous silicon dioxide particles are mixed, subjected to hydrophobic modification by a silane coupling agent, added into PVDF membrane casting solution for phase conversion to prepare SiO with alcohol penetration priority₂PVDF hybrid membranes.

2. The method of claim 1, wherein the solid silica particles have a particle size smaller than that of the mesoporous silica particles.

3. The method as claimed in claim 1, wherein the solid silica particles have a particle size of 10-40nm, and the mesoporous silica particles have a particle size of 100-200 nm.

4. Method according to claim 1, characterized in that the method comprises the steps of:

(a) mixing a proper amount of solid silicon dioxide particles and mesoporous silicon dioxide particles to obtain mixed silicon dioxide particles, and roasting at the high temperature of 200-300 ℃;

(b) adding the silicon dioxide mixed particles obtained in the step (a) into a silane coupling agent and a solvent, and reacting for 0.5-2h under the ultrasonic stirring state to obtain modified silicon dioxide mixed particles;

(c) uniformly mixing PVDF, modified silica inorganic particles, a pore-forming agent and an organic solvent, aging at 60-100 ℃ for 12-24h, and standing at 60-100 ℃ for defoaming to obtain a membrane casting solution;

(d) and uniformly blade-coating the casting solution on non-woven fabric, placing the non-woven fabric in a coagulating bath, taking out the membrane after phase inversion is finished, and drying the membrane at 40-60 ℃ to obtain the SiO2/PVDF hybrid membrane with ethanol permeation priority.

5. The method according to claim 4, wherein the mass ratio of the solid silica particles to the mesoporous silica particles in the mixed silica particles in the step (a) is 3 to 1: 1.

6. the method according to claim 4, wherein the mass ratio of the silica mixed particles to PVDF in step (c) is 1-4: 10, preferably 2 to 3: 10.

7. the method according to claim 4, wherein the pore forming agent is one or more of polyvinylpyrrolidone, polyethylene glycol, and LiCl, and the solvent is one or more of dimethylformamide, dimethylacetamide, acetone, and N-methylpyrrolidone.

8. The method according to claim 4, wherein the silane coupling agent is one of KH-550 and KH-560.

9. The method according to claim 4, wherein the content of the silane coupling agent in the solvent is 5 to 30% by weight.

Technical Field

The invention relates to a preparation method of a membrane material, in particular to SiO with preferential alcohol permeability₂A preparation method of a PVDF hybrid membrane.

Background

Bioethanol has received high attention from all countries in the world as a green, efficient and renewable novel energy source. Due to product inhibition, traditional fermentation processes only yield dilute solutions of ethanol at very low concentrations, which need to be removed from the fermentation broth in a timely manner. In the existing ethanol dehydration technology, pervaporation is a novel membrane separation technology and has the advantages of high efficiency, energy conservation, environmental protection and the like. In the prior art, alcohol-permselective pervaporation membrane and fermentation coupling technology are adopted, so that ethanol and butanol in fermentation liquor can be removed in situ in real time, and the biological fermentation efficiency and the biological alcohol yield are improved.

The most important choice in the pervaporation process is the membrane material, and at present, inorganic membranes and organic polymer membranes which are researched in the pervaporation field are expensive compared with inorganic membranes, and organic membranes are widely applied due to lower price and applicability. The polyvinylidene fluoride membrane is a common pervaporation alcohol-permselective membrane material, has the advantages of relatively low price, easiness in membrane formation, stable chemical property, good heat resistance, pollution resistance, strong hydrophobicity and the like, is a potential pervaporation membrane material, but the flux and the selectivity of the polyvinylidene fluoride membrane are found to be difficult to meet the actual application requirements in the application process.

To improve this situation, the prior art has chosen to use inorganic particles, such as zeolites, silica, MOF materials, etc., blended with polymers to produce hybrid membranes, which achieve a range of dual increases in flux and selectivity, but not so much. Therefore, there is a strong need to optimize the existing technology of inorganic particle doped PVDF membrane to further improve its flux and selectivity.

Disclosure of Invention

In order to improve the permeability of a PVDF hybrid membrane, the invention provides SiO which preferentially permeates alcohol₂The preparation method of the PVDF hybrid membrane comprises the steps of mixing solid silicon dioxide particles and mesoporous silicon dioxide particles, performing hydrophobic modification by a silane coupling agent, adding the mixture into PVDF membrane casting solution for phase conversion to prepare SiO with alcohol penetration priority₂PVDF hybrid membranes.

Preferably, the particle size of the solid silica particles is smaller than that of the mesoporous silica particles.

Preferably, the particle diameter of the solid silica particles is 10-40nm, and the particle diameter of the mesoporous silica particles is 100-200 nm.

Preferably, the method comprises the steps of:

(a) mixing a proper amount of solid silicon dioxide particles and mesoporous silicon dioxide particles to obtain mixed silicon dioxide particles, and roasting at the high temperature of 200-300 ℃;

(b) adding the silicon dioxide mixed particles obtained in the step (a) into a silane coupling agent and a solvent, and reacting for 0.5-2h under the ultrasonic stirring state to obtain modified silicon dioxide mixed particles;

(c) uniformly mixing PVDF, modified silica inorganic particles, a pore-forming agent and an organic solvent, aging at 60-100 ℃ for 12-24h, and standing at 60-100 ℃ for defoaming to obtain a membrane casting solution;

(d) uniformly coating the casting film liquid on a non-woven fabric, placing the non-woven fabric in a coagulating bath, taking out the film after phase inversion is finished, and drying the film at 40-60 ℃ to obtain the SiO with preferential alcohol permeability₂PVDF hybrid membranes.

Preferably, the mass ratio of the solid silica particles to the mesoporous silica particles in the mixed silica particles in the step (a) is 3-1: 1.

preferably, the mass ratio of the silica mixed particles to PVDF in step (c) is 1-4: 10, preferably 2 to 3: 10.

preferably, the pore-forming agent is one or more of polyvinylpyrrolidone, polyethylene glycol and LiCl, and the solvent is one or more of dimethylformamide, dimethylacetamide, acetone and N-methylpyrrolidone.

Preferably, the silane coupling agent is one of KH-550 and KH-560.

Preferably, the content of the silane coupling agent in the solvent is 5 to 30% by weight.

The principle of the invention is as follows: according to the invention, mesoporous silica particles and PVDF are blended and doped to prepare a hybrid membrane, a nano channel of the mesoporous silica is used as a separation and mass transfer channel of ethanol/water, but the hydrophobicity of PVDF is far lower than that of hydrophobically modified silica, so that the ethanol preferentially selects the mesoporous silica as the separation and transfer channel, and the capacity of PVDF as the mass transfer channel is reduced. Therefore, the solid nano-silica particles and the mesoporous silica particles are selected, so that the solid silica particles improve the hydrophobicity of the PVDF medium and balance the capacity of the PVDF medium as a mass transfer channel on the basis of ensuring that the mesoporous silica provides the mass transfer channel.

Detailed Description

The solid silica particles adopted by the invention are commercially available nano silica particles with the particle size of about 10-40nm, while the adopted mesoporous silica particles are self-made, and the preparation method is as follows: mixing cetyl trimethyl ammonium bromide, pure water, ethanol and sodium hydroxide, stirring at 80 ℃ for 1h, cooling by adopting an ice bath, dropwise adding tetraethyl orthosilicate under the stirring state, continuously heating to 80 ℃, and continuously stirring for 2 h. Filtering the silicon dioxide product, washing the silicon dioxide product with ethanol, drying the silicon dioxide product at 60 ℃ for 12 hours, and continuously roasting the silicon dioxide product in a muffle furnace at 500 ℃ for 5 hours to remove the template agent. In the above steps, cetyl trimethyl ammonium bromide, pure water, ethanol, sodium hydroxide and tetraethyl orthosilicate are mixed according to a molar ratio of 0.2: 2300:50:0.6: 2. The mesoporous silica prepared above is subjected to particle size test, and the average particle size is 180 nm.