阅读说明：本技术 一种具有光催化功能的pan基油水分离微孔膜的制备方法 (Preparation method of PAN-based oil-water separation microporous membrane with photocatalytic function ) 是由 韩娜 张浩然 张龙飞 张兴祥 张总宣 钱勇强 于 2019-12-15 设计创作，主要内容包括：本发明公开了一种具有光催化功能的PAN基油水分离微孔膜的制备方法,首先采用溶胶-凝胶法在TiO<Sub>2</Sub>的外表面引入壳层SiO<Sub>2</Sub>纳米粒子,包覆具有光催化功能的纳米TiO<Sub>2</Sub>,得到SiO<Sub>2</Sub>@TiO<Sub>2</Sub>添加剂,以隔绝基膜与光催化粒子的直接接触,同时为下一步光催化粒子向膜表面迁移打下基础；然后将SiO<Sub>2</Sub>@TiO<Sub>2</Sub>与P(AN-MA)共混制得铸膜液,再利用TIPS法使含有SiO<Sub>2</Sub>@TiO<Sub>2</Sub>添加剂的铸膜液固化成膜,再通过对固化膜进行水解反应使膜表面的氰基基团转化为亲水的羧基基团的同时,溶解添加剂壳层SiO<Sub>2</Sub>,添加剂内部的TiO<Sub>2</Sub>脱离束缚而迁移到膜表面以达到高效利用光催化粒子且不破坏基膜原有性能的目的,得到具有油水分离功能和光催化降解性能的PAN基微孔膜。本方法工艺简单、高效、无污染且对基膜渗透性不产生影响。(The invention discloses a preparation method of PAN-based oil-water separation microporous membrane with photocatalysis function, which comprises the steps of firstly adopting a sol-gel method to prepare TiO 2 Introducing shell SiO into the outer surface of 2 Nano particles coated with nano TiO having photocatalytic function 2 To obtain SiO 2 @TiO 2 Additive to insulate the base film from lightThe direct contact of the catalytic particles lays a foundation for the next step of the migration of the photocatalytic particles to the surface of the membrane; then SiO 2 @TiO 2 Mixing with P (AN-MA) to obtain casting solution, and treating with TIPS method to obtain the final product containing SiO 2 @TiO 2 The casting solution of the additive is solidified into a film, and then the cyano-group on the surface of the film is converted into the hydrophilic carboxyl group by hydrolysis reaction of the solidified film, and simultaneously the SiO of the shell layer of the additive is dissolved 2 TiO inside the additive 2 The particles are removed from the constraint and migrate to the surface of the membrane so as to achieve the aim of efficiently utilizing the photocatalytic particles without damaging the original performance of the base membrane, and obtain the PAN-based microporous membrane with the oil-water separation function and the photocatalytic degradation performance. The method has simple process, high efficiency, no pollution and no influence on the permeability of the basement membrane.)

1. A preparation method of a PAN-based oil-water separation microporous membrane with a photocatalytic function is characterized by comprising the following steps:

1) preparation of SiO by sol-gel method₂@TiO₂An additive;

2) containing SiO₂@TiO₂Preparation of PAN-based microporous membranes of additives: p (AN-MA), composite diluent and SiO₂@TiO₂Uniformly mixing the additives to obtain a uniform mixed solution; heating to 140-170 ℃ under the protection of inert gas, reacting for 60-90 min, heating the mixed solution to 160-200 ℃ after the mixed solution turns yellow, continuing reacting for 15-30 min, and defoaming to obtain a casting solution;

after the casting solution is solidified into a film, the film is placed in an extracting agent capable of dissolving the composite diluent to remove the composite diluent until the composite diluent is completely removed, so that the film containing SiO is obtained₂@TiO₂A PAN-based microporous membrane of an additive;

3) preparation of PAN-based microporous membrane with oil-water separation function and photocatalytic degradation performance: hydrolyzing the microporous membrane obtained in the step 2) in a sodium hydroxide solution with the mass fraction of 5-20 wt% for 1-8 h to obtain the PAN-based oil-water separation microporous membrane with the photocatalytic function.

2. The method for preparing a PAN-based oil-water separation microporous membrane having a photocatalytic function according to claim 1, wherein step 1) is: at room temperature, adding TiO₂Uniformly dispersing the particles in ethanol, and then adding ammonia water and deionized water to obtain TiO₂Mixing the solution; ammonia and TiO₂The mass ratio of the particles is 3-5: 1;

subjecting TE toDissolving OS in ethanol to obtain a TEOS solution; TEOS and TiO₂The mass ratio of the particles is 2-4: 1;

adding TiO into the mixture₂Transferring the mixed solution into an environment of 25-35 ℃, dropwise adding TEOS solution while stirring, washing the product to be neutral after dropwise adding, and drying to remove residual ethanol and deionized water on the product to obtain SiO₂@TiO₂And (3) an additive.

3. The method for preparing PAN-based oil-water separation microporous membrane with photocatalytic function according to claim 2, wherein in step 1), deionized water and TiO are mixed₂The mass ratio of the particles is 60: 1; TiO 2₂In the mixed solution, ethanol and TiO₂The mass ratio of the particles is 100: 0.5; in the TEOS solution, the mass ratio of ethanol to TEOS is 100: 5; removing residual ethanol and deionized water on the product in the step 1) by adopting freeze drying for 6-24 h.

4. The method for preparing the PAN-based oil-water separation microporous membrane with the photocatalytic function according to claim 1, wherein in the step 2), the casting solution is added after the mold is preheated to 100-120 ℃.

5. The method for preparing a PAN-based oil-water separation microporous membrane with a photocatalytic function according to claim 1, wherein in the step 2), the composite diluent is completely removed when the extractant has no color foam in the sun.

6. The method for preparing a PAN-based oil-water separation microporous membrane with a photocatalytic function according to claim 1, wherein in the step 2), the composite diluent comprises 0-85 wt% of a main diluent and 0-85 wt% of an auxiliary solvent, and the sum of the two is 100%; the main diluent is at least one of caprolactam, diphenyl sulfone, benzophenone, diphenyl ether, cyclohexyl pyrrolidone or benzoin; the auxiliary solvent is at least one of glyceryl triacetate, dibutyl sebacate, dimethyl phthalate, dioctyl phthalate or dioctyl adipate.

7. The method for preparing the PAN-based oil-water separation microporous membrane with the photocatalytic function according to claim 1, wherein in the step 2), P (AN-MA) accounts for 15-20% of the total mass of the P (AN-MA) and the composite diluent; the composite diluent accounts for 80-85 wt% of the total mass of the P (AN-MA) and the composite diluent; SiO 2₂@TiO₂The mass ratio of the additive to P (AN-MA) is less than or equal to 5 percent.

8. The method of claim 1, wherein in step 2), the extractant is at least one of deionized water, ethanol, ethylene glycol, propanol, acetone, or glycerol.

9. A PAN-based oil-water separation microporous membrane with a photocatalytic function, which is prepared by the preparation method of the PAN-based oil-water separation microporous membrane with a photocatalytic function according to any one of claims 1 to 8.

10. Use of the PAN-based oil-water separation microporous membrane with photocatalytic function according to claim 9 in the fields of oil-water separation and photocatalysis.

Technical Field

The invention belongs to the technical field of membrane materials, and particularly relates to a preparation method of a PAN-based oil-water separation microporous membrane with a photocatalytic function.

Background

At present, China, as a large textile country, has a plurality of printing and dyeing factories, wool dyeing factories and silk factories which mainly process cotton, hemp, chemical fibers and blended products thereof and silk, and a large amount of printing and dyeing wastewater is discharged every day. The water quality of the printing and dyeing wastewater changes complexly and violently, and the printing and dyeing wastewater has deep chroma, large change of pH value, poor biodegradability, and a large amount of organic pollutants such as aniline, nitrobenzene, phthalic acid and the like containing benzene rings, amino groups, azo groups and other groups. These substances are mostly carcinogenic and are difficult to naturally degrade by microorganisms in nature. The traditional treatment method of printing and dyeing wastewater is mostly a chemical method. The treatment method is time-consuming and labor-consuming, and is easy to cause secondary pollution. Therefore, it is important to develop a safe, green, efficient and stable treatment method for printing and dyeing wastewater, wherein the Selective Catalytic Reduction (SCR) technology has high degradation efficiency, is mature, has no secondary pollution, and is receiving more and more attention.

In selective catalytic reduction technology, the catalyst is the key to catalytic performance. However, in the field of current photocatalysis, efficient utilization and recovery of a catalyst become the most important issue. The catalyst is usually directly put into the polluted water body, and has strong catalytic effect, but has the problems of high recovery cost, easy secondary pollution and the like, the efficiency and the service life of the catalyst are greatly reduced, and the energy consumption and the economic cost of equipment are improved. The membrane material is a material which is efficient, environment-friendly and widely applied, is widely concerned in recent years, and can effectively support the catalyst.

However, the common blending method and the membrane surface hydrothermal growth method have obvious disadvantages. The catalyst is simply blended with the polymer matrix, so that the utilization rate of the catalyst is low, the supported catalyst is mostly difficult to play the best function in the membrane hole, and the water permeability of the membrane is easy to reduce. The document of application No. 201811049975.8 discloses a method for preparing an organic-inorganic composite photocatalytic film, which comprises blending polyurethane and titanium dioxide into a polymer solution containing polyethylene glycol to obtain a casting solution, and finally preparing an organic-inorganic composite film by a NIPS coating method. The prepared composite membrane has high catalyst content and good flatness, and the spectral influence range of titanium dioxide is expanded, so that the utilization rate of solar energy is improved. However, the method has the defects of poor porosity of the membrane material, low specific surface area and poor permeability of the membrane after blending.

Therefore, aiming at the problems in the prior blending technology, a loading method which can load a large amount of materials, is simple, efficient and pollution-free and does not affect the permeability of the base membrane is urgently needed to be found to make up for the defects in the prior art.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a preparation method of a PAN-based oil-water separation microporous membrane with a photocatalytic function.

The technical scheme for solving the technical problems is to provide a preparation method of a PAN-based oil-water separation microporous membrane with a photocatalytic function, which is characterized by comprising the following steps:

1) preparation of SiO by sol-gel method₂@TiO₂An additive;

2) containing SiO₂@TiO₂Preparation of PAN-based microporous membranes of additives: p (AN-MA), composite diluent and SiO₂@TiO₂Uniformly mixing the additives to obtain a uniform mixed solution; heating to 140-170 ℃ under the protection of inert gas, reacting for 60-90 min, heating the mixed solution to 160-200 ℃ after the mixed solution turns yellow, continuing reacting for 15-30 min, and defoaming to obtain a casting solution;

after the casting solution is solidified into a film, the film is placed in an extracting agent capable of dissolving the composite diluent to remove the composite diluent until the composite diluent is completely removed, so that the film containing SiO is obtained₂@TiO₂A PAN-based microporous membrane of an additive;

3) preparation of PAN-based microporous membrane with oil-water separation function and photocatalytic degradation performance: hydrolyzing the microporous membrane obtained in the step 2) in a sodium hydroxide solution with the mass fraction of 5-20 wt% for 1-8 h to obtain the PAN-based oil-water separation microporous membrane with the photocatalytic function.

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

(1) the method firstly adopts a sol-gel method to prepare TiO₂Introducing shell SiO into the outer surface of₂Nano particles coated with nano TiO having photocatalytic function₂To obtain SiO₂@TiO₂The additive is used for isolating the direct contact between the base film and the photocatalytic particles and laying a foundation for the migration of the photocatalytic particles to the surface of the film in the next step; then SiO₂@TiO₂Mixing with P (AN-MA) to obtain casting solution, and TIPS (thermally induced phase separation) to obtain a mixture containing SiO₂@TiO₂The casting solution of the additive is solidified into a film, and then the cyano-group on the surface of the film is converted into the hydrophilic carboxyl group by hydrolysis reaction of the solidified film, and simultaneously the SiO of the shell layer of the additive is dissolved₂TiO inside the additive₂The particles are removed from the constraint and migrate to the surface of the membrane so as to achieve the aim of efficiently utilizing the photocatalytic particles without damaging the original performance of the base membrane, and obtain the PAN-based microporous membrane with the oil-water separation function and the photocatalytic degradation performance.

(2) The PAN-based microporous membrane prepared by the method has the characteristics of high titanium dioxide loading rate, high porosity, large specific surface area, excellent mechanical property, excellent heat resistance and biological affinity, good photocatalytic activity and hydrophilicity, long service life and the like, is hydrophilic and oleophobic, and can effectively avoid the combination of water vapor and a catalyst.

(3) The microporous membrane with uniform pore diameter, high porosity, large specific surface area and good mechanical property is prepared by adopting a high-temperature-resistant and solvent-resistant P (AN-MA) copolymer membrane as a catalyst carrier and adopting a TIPS process, so that the effective surface area of the catalyst and the surface loading rate of the membrane are improved.

(4) The P (AN-MA) copolymer film obtains higher hydrophilicity and TiO by adopting a hydrolysis method under alkaline conditions₂The load rate and the formation of hydrogen bonds improve the mechanical strength of the microporous membrane.

(5) Nano SiO₂Plays a role of being aligned with TiO₂The protective effect of the nano-particles can be reduced and TiO can be reduced₂Agglomeration of nanoparticles to achieve TiO isolation₂Purpose of the copolymer with P (AN-MA), SiO during hydrolysis₂Reacting with NaOH to generate NaSiO₃Dissolved in water, TiO₂Released to reach the membrane surface through the membrane pores to form hydrogen bonds with carboxyl groups formed by hydrolysis on the membrane surface, so that TiO with high specific surface area₂Is fixed on the surface of a P (AN-MA) microporous membrane and is SiO₂@TiO₂Meanwhile, the function of the pore-forming agent is provided, the hydrophilicity and the porosity of the P (AN-MA) microporous membrane are further improved, good photocatalytic degradation performance is obtained, and the service life and the catalytic efficiency of the catalyst and the membrane are effectively improved.

(6) The method has simple process, high efficiency, no pollution and no influence on the permeability of the basement membrane.

Drawings

FIG. 1 shows TiO of the present invention₂Nanoparticles and SiO₂@TiO₂SEM photograph of the conversion process of the additive; FIG. 1(a) is pure TiO₂SEM photograph of nanoparticles, FIG. 1(b) is SiO₂@TiO₂SEM photographs of the composite nanoparticles;

FIG. 2 shows SiO of FIG. 1(b) according to the present invention₂@TiO₂TEM pictures at different multiples of the additive;

FIG. 3 is an SEM photograph of the membrane surface of a PAN-based oil-water separation microporous membrane having a photocatalytic function obtained in example 1 of the present invention;

fig. 4 is a graph of water contact angle values of the films prepared in example 1, comparative example 2 and comparative example 3 of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples and accompanying drawings. The specific examples are only intended to illustrate the invention in further detail and do not limit the scope of protection of the claims of the present application.

The invention provides a preparation method (short for method) of a PAN (polyacrylonitrile) -based oil-water separation microporous membrane with a photocatalytic function, which is characterized by comprising the following steps:

1)SiO₂@TiO₂preparation of the additive: at room temperature (10-35 ℃), adding TiO₂Ultrasonically and uniformly dispersing the particles in ethanol, and simultaneously adding ammonia water and deionized water to obtain TiO₂Mixing the solution; ammonia and TiO₂The mass ratio of the particles is 3-5: 1; deionized water and TiO₂The mass ratio of the particles is 60: 1; TiO 2₂Ethanol and TiO in the mixed solution₂The mass ratio of the particles is 100: 0.5;

TEOS (tetraethyl orthosilicate) is dissolved in ethanol to obtain a TEOS solution; TEOS and TiO₂The mass ratio of the particles is 2-4: 1; the mass ratio of ethanol to TEOS in the TEOS solution is 100: 5;

adding TiO into the mixture₂Transferring the mixed solution into an environment (water bath) at 25-35 ℃, dropwise adding a TEOS solution while stirring, and reacting for 2-4 h; washing the product with ethanol and deionized water to neutrality, and drying (preferably freeze drying) for 6-24 h to remove residual ethanol and deionized water on the product to obtain SiO₂@TiO₂An additive; @ denotes coating, SiO₂@TiO₂Is SiO₂Coated in TiO₂Of the entire outer surface, i.e. TiO₂Is a core, SiO₂A core-shell structure of the shell;

TiO₂the particles are made of TiO₂And (3) nanoparticles.

2) Containing SiO₂@TiO₂Preparation of PAN-based microporous membranes of additives: adding P (AN-MA) (acrylonitrile)-methyl acrylate copolymer), composite diluent and SiO₂@TiO₂Stirring and mixing the additives; then ultrasonically dispersing in water bath ultrasound for 90-100 min to obtain a uniform mixed solution; heating to 140-170 ℃ under the protection of inert gas, reacting for 60-90 min, heating the mixed solution to 160-200 ℃ after the mixed solution turns yellow, continuing reacting for 15-30 min, and defoaming to obtain a casting solution;

adding the casting solution into a die preheated to 100-120 ℃ for calendaring and forming, and then placing the whole die in a low-temperature environment capable of quickly cooling the casting solution to quickly crystallize, solidify and form a film;

then the membrane is placed in an extracting agent capable of dissolving the composite diluent to remove the composite diluent; continuously removing the composite diluent until the extractant has no obvious color foam in the sun, wherein the cured film is changed from light blue to pure white, and the composite diluent is completely removed to obtain the product containing SiO₂@TiO₂A PAN-based microporous membrane of an additive;

in the step 2), the composite diluent is formed by mixing 0-85 wt% of main diluent and 0-85 wt% of auxiliary solvent, and the mass sum of the main diluent and the auxiliary solvent is 100%; the main diluent is at least one of caprolactam, diphenyl sulfone, benzophenone, diphenyl ether, cyclohexyl pyrrolidone or benzoin; the auxiliary solvent is at least one of glyceryl triacetate, dibutyl sebacate, dimethyl phthalate, dioctyl phthalate or dioctyl adipate;

in the step 2), P (AN-MA) accounts for 15-20% of the total mass of the P (AN-MA) and the composite diluent; the composite diluent accounts for 80-85 wt% of the total mass of the P (AN-MA) and the composite diluent; SiO 2₂@TiO₂The mass ratio of the additive to P (AN-MA) is less than or equal to 5 percent and more than 0 percent;

in the step 2), the extracting agent is at least one of deionized water, ethanol, ethylene glycol, propanol, acetone or glycerol;

3) preparation of PAN-based microporous membrane with oil-water separation function and photocatalytic degradation performance: alkalifying the microporous membrane obtained in the step 2) in a sodium hydroxide solution with the mass fraction of 5-20 wt% (preferably 5-10 wt%) at room temperaturePerforming sexual hydrolysis for 1-8 h (preferably 1-5 h), converting cyano groups on the surface of the film into hydrophilic carboxyl groups after hydrolysis, and preparing SiO on the surface of the additive₂Dissolving, TiO in the additive₂The microporous membrane was removed from the restriction and migrated to obtain a PAN-based oil-water separation microporous membrane having a photocatalytic function.

The invention also provides application of the PAN-based oil-water separation microporous membrane with the photocatalytic function in the fields of oil-water separation and photocatalysis.