阅读说明：本技术 一种超亲水聚偏氟乙烯微孔膜及其制备方法和用途 (Super-hydrophilic polyvinylidene fluoride microporous membrane and preparation method and application thereof ) 是由 顾林 于 2020-07-07 设计创作，主要内容包括：本发明公开了一种超亲水聚偏氟乙烯微孔膜及其制备方法和用途。所述超亲水聚偏氟乙烯微孔膜的制备方法,包括以下步骤：一、将聚偏氟乙烯微孔膜置于碱性浸渍液中进行浸渍,所述碱性浸渍液包括纤维素、水、尿素、氢氧化钠和氢氧化锂；二、将聚偏氟乙烯微孔膜从碱性浸渍液中取出,依次放入乙醇和水中浸泡；三、将聚偏氟乙烯微孔膜从水中取出,用水洗净后晾干,即得到超亲水聚偏氟乙烯微孔膜。本发明利用纤维素作为改性剂,通过在碱性环境中沉积在聚偏氟乙烯表面,实现聚偏氟乙烯微孔膜超亲水性,并使之具备油水分离能力。本发明的制备方法简单,所制备的超亲水聚偏氟乙烯微孔膜稳定性好,油水分离效率高,可大规模制备,具有很好的工业应用前景。(The invention discloses a super-hydrophilic polyvinylidene fluoride microporous membrane, a preparation method and application thereof. The preparation method of the super-hydrophilic polyvinylidene fluoride microporous membrane comprises the following steps: firstly, placing a polyvinylidene fluoride microporous membrane in an alkaline impregnation solution for impregnation, wherein the alkaline impregnation solution comprises cellulose, water, urea, sodium hydroxide and lithium hydroxide; taking the polyvinylidene fluoride microporous membrane out of the alkaline impregnation liquid, and sequentially putting the polyvinylidene fluoride microporous membrane into ethanol and water for soaking; and thirdly, taking the polyvinylidene fluoride microporous membrane out of water, washing with water, and airing to obtain the super-hydrophilic polyvinylidene fluoride microporous membrane. The invention uses cellulose as a modifier, and the cellulose is deposited on the surface of polyvinylidene fluoride in an alkaline environment to realize the super-hydrophilicity of the polyvinylidene fluoride microporous membrane and enable the polyvinylidene fluoride microporous membrane to have oil-water separation capability. The preparation method is simple, and the prepared super-hydrophilic polyvinylidene fluoride microporous membrane has good stability and high oil-water separation efficiency, can be prepared in a large scale, and has good industrial application prospect.)

1. A preparation method of a super-hydrophilic polyvinylidene fluoride microporous membrane is characterized by comprising the following steps:

firstly, placing a polyvinylidene fluoride microporous membrane in an alkaline impregnation solution for impregnation, wherein the alkaline impregnation solution comprises cellulose, water, urea, sodium hydroxide and lithium hydroxide;

taking the polyvinylidene fluoride microporous membrane out of the alkaline impregnation liquid, and sequentially putting the polyvinylidene fluoride microporous membrane into ethanol and water for soaking;

and thirdly, taking the polyvinylidene fluoride microporous membrane out of water, washing with water, and airing to obtain the super-hydrophilic polyvinylidene fluoride microporous membrane.

2. The preparation method of the super-hydrophilic polyvinylidene fluoride microporous membrane according to claim 1, wherein the mass ratio of water to urea to sodium hydroxide to lithium hydroxide in the alkaline impregnation liquid is 80-84.6: 10-14: 5-8: 0.4-0.6.

3. The method for preparing the super-hydrophilic polyvinylidene fluoride microporous membrane according to claim 2, wherein the mass ratio of water, urea, sodium hydroxide and lithium hydroxide in the alkaline impregnation liquid is 80.5:12:7: 0.5.

4. The method for preparing a superhydrophilic polyvinylidene fluoride microporous membrane according to any one of claims 1-3, wherein the mass of the cellulose is 0.5-2% of the mass of the alkaline impregnation liquid.

5. The method for preparing the super-hydrophilic polyvinylidene fluoride microporous membrane according to claim 1, wherein the pore size of the polyvinylidene fluoride microporous membrane is 0.2-50 microns.

6. The preparation method of the super-hydrophilic polyvinylidene fluoride microporous membrane according to claim 1, wherein in the first step, the polyvinylidene fluoride microporous membrane is immersed in an alkaline immersion liquid for 2-12 hours.

7. The method for preparing a superhydrophilic polyvinylidene fluoride microporous membrane according to claim 1, wherein in the second step, the polyvinylidene fluoride microporous membrane is soaked in ethanol for 0.5-2 hours.

8. The method for preparing a superhydrophilic polyvinylidene fluoride microporous membrane according to claim 1, wherein in the second step, the polyvinylidene fluoride microporous membrane is soaked in water for 2-12 hours.

9. The super-hydrophilic polyvinylidene fluoride microporous membrane prepared according to any one of claims 1 to 8, wherein a water contact angle measured by dropping a water drop on the super-hydrophilic polyvinylidene fluoride microporous membrane is 0 °, and an underwater oil contact angle measured by dropping an oil drop under water on the surface of the super-hydrophilic polyvinylidene fluoride microporous membrane is 150 ° or more.

10. The use of the super hydrophilic polyvinylidene fluoride microporous membrane according to claim 9 in separation of oil-water mixed system.

Technical Field

The invention relates to the field of functional materials, in particular to a super-hydrophilic polyvinylidene fluoride microporous membrane, a preparation method and application thereof.

Background

The sudden and violent industrial process and frequent accidents of crude oil leakage generate a large amount of oily wastewater, and seriously threaten the environmental safety and sustainable development. The traditional oil-water separation methods, such as gravity separation, ultrasonic separation, air flotation, centrifugation, coagulation, biological treatment and the like, cannot meet the current requirements and overcome the variable environment.

Membrane separation techniques have been used to separate various emulsified oils from water due to their simple process and considerable flux. Polyvinylidene fluoride membrane has become a membrane material widely used for oil-water separation due to its good chemical stability, thermal stability, mechanical properties and the like. However, the polyvinylidene fluoride membrane is hydrophobic, even highly hydrophobic, and the hydrophobic membrane thus formed will strongly adsorb the emulsified oil, resulting in a sharp drop in water flux. Therefore, imparting super-hydrophilicity and underwater super-lipophobicity to a polyvinylidene fluoride membrane is a very effective method for solving the above-mentioned problems.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a super-hydrophilic polyvinylidene fluoride microporous membrane, a preparation method and application thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of a super-hydrophilic polyvinylidene fluoride microporous membrane comprises the following steps:

firstly, placing a polyvinylidene fluoride microporous membrane in an alkaline impregnation solution for impregnation, wherein the alkaline impregnation solution comprises cellulose, water, urea, sodium hydroxide and lithium hydroxide;

taking the polyvinylidene fluoride microporous membrane out of the alkaline impregnation liquid, and sequentially putting the polyvinylidene fluoride microporous membrane into ethanol and water for soaking;

and thirdly, taking the polyvinylidene fluoride microporous membrane out of water, washing with water, and airing to obtain the super-hydrophilic polyvinylidene fluoride microporous membrane.

The invention uses natural and cheap cellulose as a modifier, and the natural and cheap cellulose is deposited on the surface of polyvinylidene fluoride in an alkaline environment containing urea, sodium hydroxide and lithium hydroxide to realize the super-hydrophilicity of the polyvinylidene fluoride microporous membrane and enable the polyvinylidene fluoride microporous membrane to have oil-water separation capability. The preparation method is simple, and the prepared super-hydrophilic polyvinylidene fluoride microporous membrane has good stability and high oil-water separation efficiency, can be prepared in a large scale, and has good industrial application prospect.

Further, the mass ratio of water to urea to sodium hydroxide to lithium hydroxide in the alkaline impregnation liquid is 80-84.6: 10-14: 5-8: 0.4-0.6, and more preferably 80.5:12:7:0.5, and the polyvinylidene fluoride microporous membrane prepared in the proportioning range has a good super-hydrophilic effect and high oil-water separation efficiency.

Furthermore, the mass of the cellulose is 0.5-2% of that of the alkaline impregnation liquid, and the super-hydrophilic effect of the polyvinylidene fluoride microporous membrane is favorably improved.

Furthermore, the aperture of the polyvinylidene fluoride microporous membrane is 0.2-50 microns, and the prepared polyvinylidene fluoride microporous membrane has a good super-hydrophilic effect in the range.

Further, in the step one, the dipping time of the polyvinylidene fluoride microporous membrane in the alkaline dipping solution is 2-12 hours, and in the range, the modified polyvinylidene fluoride microporous membrane has a good super-hydrophilic effect.

Further, in the second step, the polyvinylidene fluoride microporous membrane is soaked in ethanol for 0.5-2 hours.

Further, in the second step, the polyvinylidene fluoride microporous membrane is soaked in water for 2-12 hours, and the prepared polyvinylidene fluoride microporous membrane has a good super-hydrophilic effect in the range.

The invention also provides the super-hydrophilic polyvinylidene fluoride microporous membrane prepared by the method, a water contact angle is 0 degree when water drops are dripped on the super-hydrophilic polyvinylidene fluoride microporous membrane, and an underwater oil contact angle is more than 150 degrees when the water drops are dripped on the surface of the super-hydrophilic polyvinylidene fluoride microporous membrane under water.

The invention also provides the application of the super-hydrophilic polyvinylidene fluoride microporous membrane in separation of an oil-water mixed system.

Compared with the prior art, the invention has the beneficial effects that:

the super-hydrophilic polyvinylidene fluoride microporous membrane prepared by the method has a water contact angle of 0 degree and super-hydrophilicity, has an underwater oil contact angle of more than 150 degrees, has super-oleophobic property, and can effectively separate oil-water emulsion.

The modifier adopted by the invention is cellulose which is derived from biomass, is safe and environment-friendly, has low price, and the prepared super-hydrophilic polyvinylidene fluoride microporous membrane has good stability and high oil-water separation efficiency, can be prepared in a large scale, and has good industrial application prospect.

Drawings

FIG. 1 is a photograph of the water contact angle of the superhydrophilic polyvinylidene fluoride microporous membrane prepared in example 1;

FIG. 2 is a photograph of a contact angle of the super-hydrophilic polyvinylidene fluoride microporous membrane prepared in example 1 with methylene chloride under water;

FIG. 3 is a photograph of the experimental apparatus for oil-water separation in examples 1 to 6;

FIG. 4 is a photograph of the contact angle of the super-hydrophilic polyvinylidene fluoride microporous membrane prepared in example 2 with toluene under water;

FIG. 5 is a photograph of the contact angle of the super-hydrophilic polyvinylidene fluoride microporous membrane prepared in example 3 with cyclohexane under water.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific examples. It will be understood by those skilled in the art that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.