Preparation method and application of a photocatalytic anti-pollution separation membrane

Abstract

The present invention discloses a preparation method and application of a photocatalytic anti-pollution separation membrane. In the present invention, lignin is used as a carbon precursor to modify TiO2, and a lignin-TiO2 composite material is prepared by a sol-gel method, and a C-Ti composite material is obtained by pyrolysis; the C-Ti composite material is introduced into a polymer solution by a phase inversion method to prepare a photocatalytic anti-pollution separation membrane. The prepared C-Ti doped membrane can effectively separate lignin and salts in the simulated pulp-making waste liquid, realize the resource utilization of waste lignin and greatly reduce the usage amount of TiO2 while ensuring a similar photocatalytic degradation efficiency for BSA pollutants and better anti-pollution performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane separation, and particularly relates to a preparation method and application of a photocatalytic anti-fouling separation membrane. Background Art

[0002] With the development of industry and cities, the demand for efficient wastewater treatment and water purification technologies is increasing. The membrane separation technology with low energy consumption, easy operation and less land occupation is developing rapidly in the separation and purification of materials. Polyvinylidene fluoride (PVDF) is widely applicable to the preparation of membranes due to its excellent mechanical strength, thermal stability and good chemical durability. However, due to the hydrophobicity and large defects of PVDF membranes, fouling problems will inevitably occur during the filtration process, thereby reducing the membrane performance and service life.

[0003] To improve the anti-fouling performance, the anti-fouling surface and interface of the membrane can be constructed by hydrophilic modification of the PVDF membrane. Currently, the methods of membrane modification are generally divided into surface coating, surface grafting, and blending modification. Among them, blending modification is recognized as the most suitable method for industrial production of modified membranes. Many researchers have modified PVDF membranes with nanoparticles, such as Al2O 3 , SiO 2 and TiO 2 . Among them, titanium dioxide (TiO 2 ) is widely used in water treatment due to its excellent activity, non-toxicity, good cost performance and good stability. However, due to its high surface energy, TiO 2 is prone to agglomeration during the preparation of mixed matrix membranes (MMMs), which has a negative impact on the membrane performance. Therefore, the modification and optimization of TiO2 materials is a promising method to reduce the surface energy and improve the membrane performance. Summary of the Invention

[0004] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract and the title, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0005] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of a photocatalytic anti-fouling separation membrane.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: including,

[0008] The C-Ti composite material is ground, mixed with a polymer and a pore-forming agent in an organic solvent, and after ultrasonic treatment, stirring and heating, a uniform casting solution is obtained.

[0009] The casting solution is coated on the surface of the non-woven fabric and phase-transformed into a membrane in a coagulation bath by the phase inversion method, thus obtaining the photocatalytic anti-pollution separation membrane.

[0010] As a preferred embodiment of the preparation method of the photocatalytic anti-pollution separation membrane described in the present invention, by mass fraction, the casting solution includes 0.1% - 3% of the C-Ti composite material, 14% - 20% of the polymer, 0.1% - 10% of the pore-forming agent, and 70% - 90% of the organic solvent.

[0011] As a preferred embodiment of the preparation method of the photocatalytic anti-pollution separation membrane described in the present invention, the C-Ti composite material is a lignin-TiO 2 composite material, and the preparation method includes

[0012] Lignin and tetrabutyl titanate are synthesized into lignin-TiO 2 material by the hydrothermal method. The lignin-TiO 2 material is calcined in an N 2 atmosphere to obtain the C-Ti composite material, wherein the mass ratio of lignin to tetrabutyl titanate is 1:0.5 - 2.

[0013] As a preferred embodiment of the preparation method of the photocatalytic anti-pollution separation membrane described in the present invention, the polymer includes polyvinylidene fluoride, polyimide, polyethersulfone, polysulfone, sulfonated polysulfone, sulfonated polyethersulfone, polyamide, and cellulose acetate.

[0014] As a preferred embodiment of the preparation method of the photocatalytic anti-pollution separation membrane described in the present invention, the pore-forming agent is polyethylene glycol with a molecular weight of 200 - 10000 Da.

[0015] As a preferred embodiment of the preparation method of the photocatalytic anti-pollution separation membrane described in the present invention, the organic solvent includes N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0016] As a preferred embodiment of the preparation method of the photocatalytic anti-pollution separation membrane described in the present invention, the ultrasonic treatment time is 1 - 3 h, the stirring time is 10 - 12 h, and the heating temperature is 60 - 80 °C.

[0017] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of the photocatalytic anti-pollution separation membrane.

[0018] As a preferred embodiment of the application of the photocatalytic anti-pollution separation membrane of the present invention, wherein: the application includes the application in the separation of lignin and salt, and the mixed solution of lignin and sulfate passes through the membrane for filtration separation, and after filtration, the membrane is cleaned and recycled;

[0019] Among them, the lignin is sulfonic acid group lignin, and the concentration is 200 ppm to 10,000 ppm;

[0020] The salt is sodium sulfate or sodium chloride, and the concentration is 200 ppm to 10,000 ppm.

[0021] As a preferred embodiment of the application of the photocatalytic anti-pollution separation membrane of the present invention, wherein: the cleaning includes soaking and rinsing the separation membrane with deionized water under low pollution conditions, and using ultraviolet light for photodegradation under high pollution conditions, wherein the ultraviolet light illumination power is 100 W to 00 W, and the time is 0.1 to 2 h.

[0022] As a preferred embodiment of the application of the photocatalytic anti-pollution separation membrane of the present invention, wherein: the application also includes degrading pollutants through photocatalysis.

[0023] Advantages of the present invention:

[0024] (1) The present invention uses lignin to modify TiO 2 , which can improve the compatibility and stability of TiO 2 during the preparation process of the mixed matrix membrane. The C-Ti material embedded in the PVDF membrane can improve the membrane filtration performance, retention performance and anti-pollution performance, realize the effective separation of lignin and salt, and endow the membrane with photocatalytic performance.

[0025] (2) While improving the anti-pollution performance of the PVDF / C-Ti photocatalytic anti-pollution separation membrane prepared by the present invention, it can also realize the resource utilization of waste lignin and reduce the usage amount of TiO 2 , providing a new direction for the utilization of waste lignin. Description of the drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings. Among them:

[0027] Figure 1 It is a comparison diagram of the PVDF / C-Ti photocatalytic anti-pollution separation membrane prepared in Example 2 of the present invention and the PVDF / TiO 2 mixed matrix membrane prepared in Comparative Example 1.

[0028] Figure 2 In (a), it is the flux decay curve graph of the membranes prepared in Example 2 of the present invention and Comparative Examples 1-2. In (b), it is the permeation flux and rejection rate graph when the membranes prepared in Example 2 of the present invention and Comparative Examples 1-2 filter BSA solution.

[0029] Figure 3 In (a), it is the flux decay curve graph of the membranes with different C-Ti contents prepared in Example 3 of the present invention and Comparative Example 3. In (b), it is the permeation flux and rejection rate graph when the membranes with different C-Ti contents prepared in Example 3 of the present invention and Comparative Example 3 filter BSA solution.

[0030] Figure 4 It is the comparison graph of the flux recovery rate (FRR), reversible fouling rate (Rr), irreversible fouling rate (Rir), and total fouling rate (Rt) of the PVDF / C-Ti photocatalytic anti-fouling separation membrane prepared in Example 2 of the present invention under different UV irradiation times.

[0031] Figure 5 In (a), it is the flux decay curve graph of the PVDF / C-Ti membrane prepared by the present invention. In (b), it is the rejection rate graph of lignin and sulfate when filtering simulated pulping waste liquor with different concentrations and the membrane flux recovery rate graph after filtration. Detailed implementation manners

[0032] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0033] Many specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0034] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that mutually excludes other embodiments.

[0035] The present invention uses a cross-flow filtration device to test the pure water permeability (PWP) of the membrane under a transmembrane pressure (TMP) of 1 bar. Subsequently, a BSA solution is introduced to test the flux and retention of BSA. The concentration of BSA is measured at 280 nm using an ultraviolet spectrophotometer. The tested membrane is rinsed with deionized water for 1 min, and then after soaking the membrane for 60 min or irradiating it with ultraviolet light for 60 min respectively, pure water is passed through to test its pure water flux under 1 bar.

[0036] Example 1

[0037] This example provides a preparation method of a C-Ti composite material.

[0038] Measure 10 mL of tetrabutyl titanate and add it to 30 mL of absolute ethanol for stirring. Add 2 mL of a 20% by mass H 2 SO 4 solution, and continue to seal and stir for 30 min;

[0039] Weigh 0.5 g of delignified lignin, add it to 6 mL of deionized water and stir evenly. Slowly drip the lignin solution into the stirred tetrabutyl titanate mixed solution, and continue to stir until the mixed solution becomes a sol-latex state. Transfer it to a high-temperature and high-pressure reaction kettle at a temperature of 120 °C and a reaction time of 2 h;

[0040] After the reaction is completed, pour out the liquid in the reaction kettle and let it stand for 24 h. Place it in a vacuum drying oven at 60 °C for drying. After gently grinding the obtained solid block sample into a powder, calcine it under nitrogen at 500 °C for 2 h to obtain the C-Ti composite material. After grinding, sieve it through a 600-mesh molecular sieve for use in other examples.

[0041] Example 2

[0042] This example provides a preparation method of a PVDF / C-Ti photocatalytic anti-fouling separation membrane.

[0043] Weigh 0.04 g (0.2 wt%) of the C-Ti composite material and add it to 16.4 g (solid content 82 wt%) of N,N-dimethylacetamide (DMAc) organic solvent. After ultrasonic treatment for 2 h, add 0.4 g (solid content 2 wt%) of polyethylene glycol (PEG400) and 3.2 g (solid content 16 wt%) of polyvinylidene fluoride (PVDF) to it, and stir at 70 °C for 12 h;

[0044] Turn off the heating and stirring device, and let it stand for 12 h to obtain a casting solution;

[0045] Use a 150-μm scraper to make a membrane on the non-woven fabric, and then put the scraped membrane into deionized water for 15 min; store the membrane after phase transition in fresh deionized water for 24 h to obtain the PVDF / C-Ti photocatalytic anti-fouling separation membrane.

[0046] Comparative Example 1

[0047] This example provides a method for preparing a PVDF / TiO 2 mixed matrix membrane.

[0048] Weigh 0.04 g (0.2 wt%) of titanium dioxide (TiO 2 ) and add it to 16.4 g (solid content 82 wt%) of N,N-dimethylacetamide (DMAc) organic solvent. After ultrasonic treatment for 2 h, add 0.4 g (solid content 2 wt%) of polyethylene glycol (PEG400) and 3.2 g (solid content 16 wt%) of polyvinylidene fluoride (PVDF) to it, and stir at 70 °C for 12 h;

[0049] Turn off the heating and stirring device, and let it stand for 12 h to obtain a casting solution;

[0050] Use a 150-μm doctor blade to make a membrane on the non-woven fabric, and then put the scraped membrane into deionized water for 15 min; store the membrane after phase transition in fresh deionized water for 24 h to obtain the PVDF / TiO 2 mixed matrix membrane.

[0051] Comparative Example 2

[0052] This example provides a method for preparing a PVDF / C mixed matrix membrane.

[0053] Weigh 0.04 g (0.2 wt%) of activated carbon (C) and add it to 16.4 g (solid content 82 wt%) of N,N-dimethylacetamide (DMAc) organic solvent. After ultrasonic treatment for 2 h, add 0.4 g (solid content 2 wt%) of polyethylene glycol (PEG400) and 3.2 g (solid content 16 wt%) of polyvinylidene fluoride (PVDF) to it, and stir at 70 °C for 12 h;

[0054] Turn off the heating and stirring device, and let it stand for 12 h to obtain a casting solution;

[0055] Use a 150-μm doctor blade to make a membrane on the non-woven fabric, and then put the scraped membrane into deionized water for 15 min; store the membrane after phase transition in fresh deionized water for 24 h to obtain the PVDF / C mixed matrix membrane.

[0056] Figure 1 It is a comparison chart of the PVDF / C-Ti photocatalytic anti-pollution separation membrane prepared in Example 2 of the present invention and the PVDF / TiO 2 mixed matrix membrane prepared in Comparative Example 1. It can be seen that the PVD F / C-Ti membrane prepared by the present invention has larger and more uniformly dispersed pores than the PVDF / TiO 2 mixed matrix membrane.

[0057] Figure 2 For the PVDF / C-Ti photocatalytic anti-pollution separation membrane prepared in Example 2 of the present invention, the PVDF / TiO 2 mixed matrix membrane prepared in Comparative Example 1, and the PVDF / C mixed matrix membrane prepared in Comparative Example 2, the flux decay curve diagrams, the comparison diagrams of the permeation flux and rejection rate of the BSA solution. Among them, Figure 2 (a) are the flux decay curve diagrams of the membranes prepared by adding C-Ti composite material, titanium dioxide (TiO 2 ) and activated carbon (C) respectively, filtering pure water, BSA solution, then filtering pure water after soaking the membrane, and filtering pure water after ultraviolet light irradiation; Figure 2 (b) are the comparison diagrams of the solution permeation flux and rejection rate when the membranes prepared by adding C-Ti composite material, titanium dioxide (TiO 2 ) and activated carbon (C) respectively filter the BSA solution.

[0058] Comparison Figure 2 (a) It can be seen that the pure water permeation flux of the PVDF / C-Ti membrane after ultraviolet light treatment is significantly higher than that of the membranes added with activated carbon or titanium dioxide. From Figure 2 (b), it can be known that the BSA rejection rate and the BSA solution permeation flux of the PVDF / C-Ti membrane are both relatively high. Although the BSA solution permeation flux of the membrane added with activated carbon is relatively high, the rejection rate is only 35%. For the membrane added with TiO 2 , although the rejection rate is relatively high, the solution permeation flux is only 18%. Thus, it can be seen that the anti-pollution performance of the PVDF / C-Ti membrane prepared by the present invention is significantly better than the other two membranes, and both the separation ability and efficiency are relatively good.

[0059] Example 3

[0060] This example explores the influence of the content of C-Ti composite material in the casting solution on the membrane performance.

[0061] Weigh 0.02, 0.04, 0.1, 0.2 g (0.1 wt%, 0.2 wt%, 0.5 wt%, 1.0 wt%) of C-Ti composite material respectively and add them to 16.4 g (solid content 82 wt%) of N,N-dimethylacetamide (DMAc) organic solvent. After ultrasonic treatment for 2 h, add 0.4 g (solid content 2 wt%) of polyethylene glycol (PEG400) and 3.2 g (solid content 16 wt%) of polyvinylidene fluoride (PVDF) to it, and stir at 70 °C for 12 h;

[0062] Turn off the heating and stirring device, and let it stand for 12 h to obtain the casting solution;

[0063] A film was made on the non-woven fabric using a 150-μm doctor blade, and then the scraped film was placed in deionized water for 15 min; the film after phase change was stored in fresh deionized water for 24 h, and thus a PVDF / C-Ti photocatalytic anti-fouling separation membrane with different contents of C-Ti composite material was obtained.

[0064] Comparative Example 3

[0065] This example provides a method for preparing a pure PVDF membrane.

[0066] Weigh 16.4 g (solid content 82 wt%) of N,N-dimethylacetamide (DMAc) organic solvent, add 0.4 g (solid content 2 wt%) of polyethylene glycol (PEG400) and 3.2 g (solid content 16 wt%) of polyvinylidene fluoride (PVDF) thereto, and stir at 70 °C for 12 h; turn off the heating and stirring device and let it stand for 12 h to obtain a casting solution;

[0067] Use a 150-μm doctor blade to make a film on the non-woven fabric, and then place the scraped film in deionized water for 5 min; store the film after phase inversion in fresh deionized water for 24 h to obtain a pure PVDF membrane.

[0068] Figure 3 It is a graph of flux decay, a comparison graph of BSA solution permeation flux and rejection rate for membranes with different C-Ti contents prepared in Example 3 and Comparative Example 3 of the present invention. Among them, Figure 3 (a) is a graph of flux decay of membranes with different C-Ti contents filtering pure water, BSA solution, the soaked membrane filtering pure water again, and the membrane after UV irradiation filtering pure water again, Figure 3 (b) is a comparison graph of solution permeation flux and rejection rate when membranes with different C-Ti contents filter BSA solution.

[0069] From Figure 3 (a), it can be seen that as the content of C-Ti composite material increases, the anti-fouling performance and photocatalytic decontamination performance of the separation membrane are improved, and when the concentration of C-Ti composite material is 0.2 wt%, the performance reaches the optimum. From Figure 3 (b), it can be seen that when the concentration of C-Ti composite material is 0.2 wt%, the rejection rate of BSA is the highest. In summary, when the concentration of C-Ti composite material is 0.2 wt%, the performance of the prepared membrane reaches the best.

[0070] Example 4

[0071] This example explores the influence of the UV irradiation cleaning time after membrane application on the membrane recovery effect.

[0072] Take the membrane prepared in Example 2 and test the pure water permeability (PWP) of the PVDF / C-Ti membrane using a cross-flow filtration device at a transmembrane pressure (TMP) of 1 bar. Then, introduce a BSA solution to test the flux and retention of BSA. Measure the concentration of BSA at 280 nm using an ultraviolet spectrophotometer. Rinse the tested membrane with deionized water for 1 min. Then, irradiate the membrane with ultraviolet light for 10 min, 20 min, 30 min, 60 min, and 90 min respectively, and then introduce pure water again to test its pure water flux at 1 bar. The results are as Figure 4 shown.

[0073] Figure 4 This is a comparison chart of the flux recovery rate, reversible fouling rate, irreversible fouling rate, and total fouling rate of the PVDF / C-Ti photocatalytic anti-fouling separation membrane prepared in Example 2 of the present invention under different ultraviolet irradiation times. Among them, FRR is the flux recovery rate, Rr is the reversible fouling rate, Rir is the irreversible fouling rate, and Rt is the total fouling rate, that is, the sum of Rr and Rir.

[0074] From Figure 4 it can be seen that as the irradiation time increases, the flux recovery rate of the membrane gradually increases, and basically remains unchanged after the irradiation time is greater than 60 min. At the same time, under the condition of unchanged total fouling rate, the reversible fouling rate of the membrane gradually increases, and the irreversible fouling rate gradually decreases, that is, the irreversible fouling is converted into reversible fouling, indicating that the anti-fouling property of the membrane is improved. When the ultraviolet irradiation treatment time is 60 min, the anti-fouling performance of the membrane is the best.

[0075] Example 5

[0076] This example explores the effect of the PVDF / C-Ti membrane prepared by the present invention on separating lignin and salt.

[0077] Use a cross-flow filtration device to test the pure water permeability (PWP) of the PVDF / C-Ti membrane at a transmembrane pressure (TMP) of 1 bar. Then, introduce a mixed solution of sodium lignosulfonate with different concentrations (200 - 10000 ppm) and 10000 ppm of sodium sulfate to test the separation effect on lignin with different concentrations. Measure the concentration of LS at 280 nm using an ultraviolet spectrophotometer. Rinse the tested membrane with deionized water for 1 min. Then, soak the membrane for 60 min and then introduce pure water to test its pure water flux at 1 bar, and test its pure water flux again after ultraviolet irradiation for 60 min. The results are as Figure 5 shown.

[0078] Figure 5This is the flux decay curve graph of the PVDF / C-Ti photocatalytic anti-pollution separation membrane prepared in Example 2 of the present invention, as well as the effect comparison graph of filtering simulated pulping waste liquid with different concentrations to separate sodium lignosulfonate and sodium sulfate, and the comparison graph of the membrane flux recovery rate after separation. Among them, Figure 5 (a) is the flux decay curve graph of the PVDF / C-Ti membrane filtering pure water, simulated pulping waste liquid with different concentrations, and then filtering pure water after the membrane is irradiated with ultraviolet light. Figure 5 (b) is the comparison graph of the rejection rates of sodium lignosulfonate and sulfate when the PVDF / C-Ti membrane filters simulated pulping waste liquid with different concentrations, and the membrane flux recovery rate after ultraviolet light treatment. The simulated pulping waste liquid is composed of sodium lignosulfonate and sulfate. When the concentration of sodium sulfate is controlled at 10,000 ppm, the lignin concentration is adjusted to be 200 - 10,000 ppm respectively.

[0079] From Figure 5 (a), it can be seen that the water flux of the membrane recovers to a certain extent after being irradiated with ultraviolet light after filtering the simulated pulping waste liquid. According to Figure 5 (b), it can be seen that when the concentration of sodium lignosulfonate in the pulping waste liquid is 200 ppm, the rejection rate of the membrane to sodium lignosulfonate is greater than 70%, and the rejection rate to sodium sulfate is less than 10%. It can be seen that the membrane has a good separation effect on sodium lignosulfonate and sodium sulfate. At the same time, when the concentration of sodium lignosulfonate in the pulping waste liquid is 10,000 ppm, the flux recovery rate can reach more than 50%, and the rejection rate to lignin can still reach more than 65%. This shows that the PVDF / C-Ti membrane prepared by the present invention has better anti-pollution performance, separation ability and efficiency.

[0080] The present invention uses lignin to modify TiO 2 , which can improve the compatibility and stability of TiO 2 in the preparation process of the mixed matrix membrane. The C-Ti material embedded in the PVDF membrane can improve the membrane filtration performance, rejection performance and anti-pollution performance, realize the effective separation of sulfonic acid group lignin and salt, endow the membrane with photocatalytic performance, and at the same time can realize the resource utilization of waste lignin and reduce the usage amount of TiO 2 , providing a new direction for the utilization of waste lignin.

[0081] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A preparation method of a photocatalytic anti-pollution separation membrane, characterized in that: it includes grinding C-Ti composite material and adding polymer and pore former into an organic solvent for mixing, and after ultrasonic treatment, stirring and heating, a uniform casting solution is obtained; the casting solution is coated on the surface of non-woven fabric and phase-transformed into a membrane in a coagulation bath by the phase inversion method, thus obtaining the photocatalytic anti-pollution separation membrane; by mass fraction, the casting solution includes 0.2% of C-Ti composite material, 14% - 20% of polymer, 0.1% - 10% of pore former and 70% - 90% of organic solvent; The C-Ti composite material is a lignin-TiO 2 composite material. The preparation method includes synthesizing the lignin-TiO 2 material by hydrothermal method using lignin and tetrabutyl titanate. The lignin-TiO 2 material is calcined in an N 2 atmosphere to obtain the C-Ti composite material, where the mass ratio of lignin to tetrabutyl titanate is 1:0.5-2; when the prepared photocatalytic anti-pollution separation membrane is used for the separation of sulfonated lignin and salt, its retention performance for sulfonated lignin is greater than 70%, and its retention performance for sodium sulfate is less than 10%, having a good separation effect; after separating sulfonated lignin with a concentration of 10000 ppm, the membrane flux recovery rate reaches more than 50% after being irradiated by ultraviolet light for more than 60 min.

2. The preparation method of the photocatalytic anti-pollution separation membrane as described in claim 1, characterized in that: the polymer includes polyvinylidene fluoride, polyimide, polysulfone, polyethersulfone, sulfonated polysulfone, sulfonated polyethersulfone, polyamide, cellulose acetate.

3. The preparation method of the photocatalytic anti-pollution separation membrane as described in claim 1, characterized in that: the pore former is polyethylene glycol with a molecular weight of 200 - 10000 Da.

4. The preparation method of the photocatalytic anti-pollution separation membrane as described in claim 1, characterized in that: the organic solvent includes N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide.

5. The preparation method of the photocatalytic anti-pollution separation membrane as described in claim 1, characterized in that: the ultrasonic time is 1 - 3 h, the stirring time is 10 - 12 h, and the heating temperature is 60 - 80 °C.

6. The application of the photocatalytic anti-pollution separation membrane prepared by the method as described in claim 1, characterized in that: the application includes the application in the separation of sulfonated lignin and salt, and the mixed solution of sulfonated lignin and salt passes through the membrane for filtration separation, and after filtration, the membrane is cleaned and recycled; wherein, the concentration of the sulfonated lignin is 200 ppm - 10000 ppm; the salt is sodium sulfate or sodium chloride with a concentration of 200 ppm - 10000 ppm.

7. The application of the photocatalytic anti-pollution separation membrane as described in claim 6, characterized in that: the cleaning includes soaking and rinsing the separation membrane with deionized water in case of low pollution, and using ultraviolet light for photocatalytic degradation in case of high pollution, wherein the ultraviolet light irradiation power is 100 W and the time is 1 h.

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