Preparation method and application of super-hydrophilic composite membrane for removing various pollutants in water body

Abstract

The application belongs to the technical field of composite membrane materials, and particularly relates to a preparation method and application of a super-hydrophilic composite membrane capable of removing various pollutants in water bodies; the preparation method comprises the following steps: preparing a bimetallic organic framework material FeZr-MOF through a one-step solvothermal method; dispersing FeZr-MOF powder in a suitable solvent, mixing, adding polyvinylidene fluoride and polyvinylpyrrolidone, stirring under water bath conditions at 30-80 DEG C, obtaining a uniformly mixed casting solution, and then preparing a FeZr-MOF / PVDF composite membrane through a non-solvent induced phase separation method after ultrasonic defoaming treatment; then, a polyaniline coating layer is in-situ polymerized on the surface of the composite membrane to obtain a PANI / FeZr-MOF / PVDF composite membrane. The super-hydrophilic composite membrane capable of removing various pollutants in water bodies has good effects in oil-water separation, removal of antibiotics and chromium ions in water and the like.

Description

Technical Field

[0001] This invention relates to the field of composite membrane materials technology, and in particular to a method for preparing and applying a superhydrophilic composite membrane that can be used to remove various pollutants from water. Background Technology

[0002] In recent years, various treatment technologies, including adsorption, flocculation, biological treatment, and membrane separation, have been developed to remove various pollutants from water. Among them, membrane separation technology has significant advantages in practical applications due to its low energy consumption, high separation efficiency, and simple process. Polyvinylidene fluoride (PVDF) possesses excellent thermal, mechanical, and chemical stability, making it a widely used membrane material with good overall performance. However, traditional single-function separation membranes can only demulsify or adsorb organic pollutants and heavy metal ions in wastewater, failing to meet the requirements for treating complex wastewater. Furthermore, membrane fouling leads to a gradual decline in separation performance over long-term use. Therefore, there is an urgent need to develop multifunctional separation membranes with superhydrophilicity and self-cleaning capabilities to meet the high requirements of treating complex wastewater.

[0003] Photocatalysis technology utilizes ultraviolet or visible light to drive chemical reactions, thereby decomposing most organic pollutants and some toxic inorganic substances. It is characterized by its green and energy-saving nature, aligning with the societal demands for sustainable development. Combining photocatalysis with membrane separation technology allows for the simultaneous purification of wastewater and the degradation of pollutants through photocatalysis, mitigating membrane fouling and enabling the development of high-performance separation membranes for treating complex wastewater. Furthermore, by modifying the membrane surface, superhydrophilic, multifunctional separation membranes can be prepared, suitable for treating oily wastewater systems. Summary of the Invention

[0004] The purpose of this invention is to provide a superhydrophilic composite membrane that can be used to remove multiple types of pollutants from water, its preparation method and application, so as to solve the technical problems such as the limitation of traditional single-function membranes that can only remove one type of pollutant and the reduction in separation efficiency caused by membrane fouling.

[0005] The present invention provides a method for preparing a superhydrophilic composite membrane that can be used to remove multiple pollutants from water, comprising the following preparation steps:

[0006] FeZr-MOF, a bimetallic organic framework material, was prepared by a one-step solvothermal method.

[0007] FeZr-MOF powder was dispersed in a suitable solvent, mixed well, and then PVDF and PVP were added. The mixture was stirred under a water bath at 30-80℃ to obtain a uniformly mixed casting solution. After ultrasonic degassing, FeZr-MOF / PVDF composite membranes were prepared using the NIPS method.

[0008] Then, a PANI coating is polymerized in situ on the surface of the composite membrane to obtain a PANI / FeZr-MOF / PVDF composite membrane.

[0009] Preferably, the preparation steps of the bimetallic organic framework material FeZr-MOF include:

[0010] 2-Aminoterephthalic acid was dissolved in N,N-dimethylformamide, and ferric chloride hexahydrate and zirconium tetrachloride were added and mixed. The mixture was reacted at 100-150℃ for 24-48 h. After cooling to room temperature, the precipitate was collected, dried, and powdered bimetallic organic framework material FeZr-MOF was obtained.

[0011] Preferably, the molar ratio of ferric chloride hexahydrate, zirconium tetrachloride, 2-aminoterephthalic acid, and N,N-dimethylformamide is (1-9):(1-9):10:(650-1000). Preferably, when the FeZr-MOF powder is dispersed in a suitable solvent, the suitable solvent is N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone.

[0012] Preferably, the mass ratio of FeZr-MOF powder, suitable solvent, PVDF and PVP is (1-3):(45-50):8.5:(1.5-2.5).

[0013] Preferably, the specific steps of the NIPS method include: taking an appropriate amount of casting solution onto a glass plate, scraping it into a film using a 100-300μm film scraper, and then immersing it in a deionized water bath at room temperature to form a film.

[0014] Preferably, the steps for in-situ polymerization of PANI coating on FeZr-MOF / PVDF surface are as follows: a certain amount of aniline is added to a 0.5-2 mol / L protic acid solution, denoted as solution A; a certain amount of ammonium persulfate is weighed and dissolved in water, denoted as solution B; solutions A and B are mixed evenly, and then the FeZr-MOF / PVDF composite membrane is added, and the reaction is carried out at room temperature for more than 5 hours.

[0015] Preferably, the mass ratio of aniline, protic acid solution, ammonium persulfate and water is 1.87:(30-50):(0.046-0.69):(30-50).

[0016] This invention also provides a superhydrophilic composite membrane prepared by the method described above for removing multiple pollutants from water. This invention further provides an application of the superhydrophilic composite membrane described above for removing multiple pollutants from water in oil-water separation and the removal of antibiotics and heavy metals from water. The superhydrophilic composite membrane for removing multiple pollutants from water, its preparation method, and its application provided by this invention have the following advantages compared to existing technologies:

[0017] 1. The superhydrophilic composite membrane provided by the present invention is composed of FeZr-MOF uniformly distributed inside the PVDF membrane and PANI grown in situ on the surface of the PVDF membrane, which can simultaneously remove multiple pollutants from water.

[0018] 2. The superhydrophilic composite membrane provided by this invention is prepared using the NIPS method, which is simple to operate, low in cost, and suitable for industrial production and application. Specifically, the FeZr-MOF powder is prepared using a one-step solvothermal method, simplifying the preparation process; the PANI coating is formed through in-situ polymerization, greatly improving the hydrophilicity of the composite membrane.

[0019] 3. The superhydrophilic composite membrane provided by this invention can simultaneously remove multiple pollutants from water. For example, the oil-water separation effect is close to 100%, the removal rate of antibiotics in water is over 90%, and the removal rate of toxic high-valent chromium ions in water is about 80%. Attached Figure Description

[0020] Figure 1 Scanning electron microscope (SEM) image of the surface of the composite film prepared for the example;

[0021] Figure 2 (a) XRD patterns of Zr-MOF and FeZr-MOF powder samples; (b) XRD patterns of PVDF, FeZr-MOF / PVDF and PANI / FeZr-MOF / PVDF film samples;

[0022] Figure 3 The water contact angle of the composite membranes prepared for all comparative examples and embodiments;

[0023] Figure 4 Results of darkroom adsorption and photo-Fenton purification of 40 mg / L oxytetracycline hydrochloride aqueous solution using composite membranes prepared for all comparative examples and embodiments.

[0024] Figure 5 Results of dark chamber adsorption and light reduction removal of 10 mg / L hexavalent chromium aqueous solution by composite membranes prepared for all comparative examples and embodiments.

[0025] Figure 6 The results of separating different oil-water mixed emulsions using the composite membrane prepared for the example. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] A method for preparing a superhydrophilic composite membrane that can be used to remove multiple pollutants from water, characterized by comprising the following steps:

[0028] S1) Bimetallic organic framework material FeZr-MOF was prepared by a one-step solvothermal method;

[0029] S2) Disperse FeZr-MOF powder in a suitable solvent, mix well, add PVDF and PVP, stir under a water bath at 30-80℃ to obtain a uniformly mixed casting solution, and after ultrasonic degassing treatment, prepare FeZr-MOF / PVDF composite membrane using the NIPS method.

[0030] S3) In situ polymerization of PANI coating on the surface of composite membrane to obtain PANI / FeZr-MOF / PVDF composite membrane.

[0031] Specifically, the preparation steps of the bimetallic organic framework material FeZr-MOF include:

[0032] 2-Aminoterephthalic acid was dissolved in N,N-dimethylformamide, and ferric chloride hexahydrate and zirconium tetrachloride were added and mixed. The mixture was reacted at 100-150℃ for 24-48 h. After cooling to room temperature, the precipitate was collected, dried, and the powdered bimetallic organic framework material FeZr-MOF was obtained. Specifically, the molar ratio of ferric chloride hexahydrate, zirconium tetrachloride, 2-aminoterephthalic acid, and N,N-dimethylformamide was (1-9):(1-9):10:(650-1000).

[0033] Specifically, the molar ratio of ferric chloride hexahydrate, zirconium tetrachloride, 2-aminoterephthalic acid and N,N-dimethylformamide is 5:5:10:(650-1000).

[0034] Specifically, when FeZr-MOF powder is dispersed in a suitable solvent, the suitable solvent is N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone.

[0035] Specifically, when FeZr-MOF powder is dispersed in a suitable solvent, the suitable solvent is N,N-dimethylformamide.

[0036] Specifically, the mass ratio of FeZr-MOF powder, suitable solvent, PVDF and PVP is (1-3):(45-50):8.5:(1.5-2.5).

[0037] Specifically, the mass ratio of FeZr-MOF powder, N,N-dimethylformamide, PVDF and PVP is 3:(45-50):8.5:2.5.

[0038] Specifically, the steps of the NIPS method include: taking an appropriate amount of casting solution onto a glass plate, scraping it into a film using a 100-300μm film scraper, and then immersing it in a deionized water bath at room temperature to form a film.

[0039] Specifically, the steps for in-situ polymerization of a PANI coating on the FeZr-MOF / PVDF surface are as follows:

[0040] A certain amount of aniline was added to a 0.5-2 mol / L protic acid solution, denoted as solution A; a certain amount of ammonium persulfate was weighed and dissolved in water, denoted as solution B; solutions A and B were mixed evenly, and a FeZr-MOF / PVDF composite membrane was added, and the reaction was carried out at room temperature for more than 5 hours. Specifically, the mass ratio of aniline, protic acid solution, ammonium persulfate and water was 1.87:(30-50):(0.046-0.69):(30-50).

[0041] Specifically, the mass ratio of aniline, 1 mol / L hydrochloric acid solution, ammonium persulfate and water is 1.87:50:0.46:50.

[0042] The present invention also provides a superhydrophilic composite membrane obtained based on the superhydrophilic composite membrane preparation method described in any one of the above-mentioned methods for removing multiple types of pollutants from water.

[0043] The present invention also provides an application of a superhydrophilic composite membrane, as described above, which can be used to remove various pollutants from water, in oil-water separation, photo-Fenton degradation of antibiotics, and photo-reduction of hexavalent chromium.

[0044] The superhydrophilic composite membrane provided by this invention is formed by uniformly distributing FeZr-MOF powder inside a PVDF membrane and uniformly distributing PANI on the surface of the PVDF membrane. The bimetallic organic framework material FeZr-MOF effectively improves the porosity of the superhydrophilic composite membrane. The synergistic effect of the bimetals enhances the adsorption performance of antibiotics and hexavalent chromium. The PANI coating significantly improves the hydrophilicity and hexavalent chromium adsorption performance of the composite membrane. FeZr-MOF endows the superhydrophilic composite membrane with photocatalytic and Fenton catalytic properties, resulting in a superhydrophilic composite membrane with excellent photo-Fenton degradation of antibiotics and photoreduction of hexavalent chromium.

[0045] Example

[0046] Preparation of superhydrophilic composite membrane (sample 1)

[0047] 101) 1.0 mmol ferric chloride hexahydrate, 1.0 mmol zirconium tetrachloride and 2.0 mmol 2-aminoterephthalic acid were dissolved in 35 mL of N,N-dimethylformamide and stirred for 30 min. The mixture was then transferred to a reaction vessel and reacted at 120 °C for 24 h. After cooling to room temperature, the precipitate was collected, washed and dried to obtain the powdered bimetallic organic framework material FeZr-MOF.

[0048] 102) Weigh 0.30g of bimetallic organic framework material FeZr-MOF and add it to N,N-dimethylformamide. Stir magnetically at room temperature for 20min. Add 0.85g of PVDF and 0.25g of PVP. Stir in a water bath at 60℃ for 5h to obtain a uniformly mixed casting solution. After ultrasonic degassing, take an appropriate amount of casting solution on a glass plate and scrape it into a film using a 200μm film scraper. Then immerse it in a deionized water bath at room temperature to form a film, labeled as FeZr-MOF / PVDF.

[0049] 103) Add 1.83 mL of aniline to 50 mL of 1 mol / L hydrochloric acid solution, and label it as solution A; weigh 0.46 g of ammonium persulfate and dissolve it in water, and label it as solution B; then pour solution A into solution B, stir, mix evenly, add FeZr-MOF / PVDF composite membrane, react at room temperature for 5 h, wash with deionized water, dry, and label it as PANI / FeZr-MOF / PVDF.

[0050] The comparative example is an improvement based on the embodiment. The content disclosed in the embodiment will not be repeated in this comparative example.

[0051] Sample 2 was prepared. The difference between Sample 2 and Sample 1 is that Sample 2 did not undergo in-situ polymerization of aniline. The obtained Sample 2 was labeled as FeZr-MOF / PVDF.

[0052] Comparative Example 2

[0053] This comparative example is an improvement based on the embodiments. The contents disclosed in the embodiments will not be repeated in this comparative example.

[0054] Sample 3 was prepared. The difference between Sample 3 and Sample 1 is that the bimetallic organic framework material FeZr-MOF was not added. The obtained Sample 3 was labeled as PANI / PVDF.

[0055] Comparative Example 3

[0056] This comparative example is an improvement based on the embodiments. The contents disclosed in the embodiments will not be repeated in this comparative example.

[0057] Sample 4 was prepared. The difference between Sample 4 and Sample 1 is that the bimetallic organic framework material FeZr-MOF was not added and the in-situ polymerization of aniline was not carried out. The obtained Sample 4 was labeled as PVDF.

[0058] like Figure 1 As shown, scanning electron microscopy (SEM) analysis of the composite membrane revealed that FeZr-MOF was uniformly distributed within the polyvinylidene fluoride (PVDF) membrane, and PANI was uniformly distributed on the membrane surface. Figure 2 As shown in (a), X-ray diffraction analysis was performed on Zr-MOF and FeZr-MOF powder samples. The diffraction peaks of Zr-MOF and FeZr-MOF are similar, indicating that the introduction of Fe did not disrupt the crystal structure of Zr-MOF. Compared to Zr-MOF, the two diffraction peaks of FeZr-MOF at 7.1° and 8.2° are slightly shifted, proving that Fe is uniformly doped in Zr-MOF. Figure 2 As shown in (b), X-ray diffraction was used to analyze the PVDF, FeZr-MOF / PVDF, and PANI / FeZr-MOF / PVDF film samples. The diffraction peak at 7.5° confirmed that FeZr-MOF was uniformly incorporated into the PVDF film. However, no new diffraction peaks appeared after PANI polymerized on the FeZr-MOF / PVDF film surface, possibly due to the lower crystallinity of PANI. Figure 3 As shown, the PVDF, FeZr-MOF / PVDF, PANI / PVDF, and PANI / FeZr-MOF / PVDF membrane samples were analyzed using a contact angle meter. The PVDF membrane exhibited a hydrophobic state, while the FeZr-MOF / PVDF and PANI / PVDF membranes exhibited a hydrophilic state. However, the water contact angle of the PANI / FeZr-MOF / PVDF membrane was only 4.8°, indicating that it has superhydrophilic properties. This is the result of the combined effect of the PANI hydrophilic coating and the FeZr-MOF hydrophilic material.

[0059] Application Example 1 applies the composite membranes prepared in all comparative examples and examples to the adsorption of oxytetracycline hydrochloride (OTC).

[0060] (1) Prepare a 40 mg / L OTC aqueous solution and measure the absorbance of the original solution using a UV spectrophotometer;

[0061] (2) Take a membrane and place it on the self-made dynamic membrane device. Pour 50 mL of 40 mg / L OTC aqueous solution into the device to adsorb OTC.

[0062] (3) Take the solution after passing through the membrane, measure the absorbance, and calculate the OTC adsorption rate. The characteristic absorption wavelength of OTC is 353 nm.

[0063] Application Example 2: All composite membranes prepared in the comparative examples and examples were applied to photo-Fenton degradation of OTC. (1) A 40 mg / L OTC aqueous solution was prepared, and the absorbance of the original solution was measured using a UV spectrophotometer;

[0064] (2) Place a membrane onto a self-made dynamic membrane transfer device, pour 50 mL of 40 mg / L OTC aqueous solution into the device, and simultaneously add 10 μL of 30% hydrogen peroxide solution. Use a light intensity of 200 mW / cm². 2 Xenon lamp irradiation is used to photo-Fenton degrade OTC;

[0065] (3) Take the solution after passing through the membrane, measure the absorbance, and calculate the OTC degradation rate.

[0066] Figure 4 Graphs showing the adsorption and photo-Fenton degradation effects of the composite membranes prepared in all comparative examples and embodiments on OTC. Figure 4 It can be seen that the PANI / FeZr-MOF / PVDF membrane exhibits the best adsorption and photo-Fenton degradation effects for OTC, with an adsorption efficiency of 81.6% and a photo-Fenton degradation efficiency of 91.8%. The significant improvement in adsorption and photo-Fenton degradation effects is mainly due to the introduction of the PANI hydrophilic coating, which increases the contact area between the FeZr-MOF catalyst and the pollutants.

[0067] Application Example 3: All composite membranes prepared in the comparative examples and examples were applied to adsorb hexavalent chromium (Cr(VI)). (1) Prepare an aqueous solution of Cr(VI) with a concentration of 10 mg / L and pH=2, and quantitatively detect the initial Cr(VI) concentration using the diphenylcarbazide spectrophotometric method (standard GB / T 7467-1987); (2) Take a membrane and place it on a self-made dynamic membrane device, pour 50 mL of an aqueous solution of Cr(VI) with a concentration of 10 mg / L and pH=2 into the device, and adsorb Cr(VI);

[0068] (3) Take the solution after membrane treatment, determine the residual Cr(VI) concentration, and calculate the Cr(VI) adsorption rate. The characteristic absorption wavelength is 540 nm.

[0069] Application Example 4: All composite films prepared in the comparative examples and examples were applied to the photoreduction of Cr(VI).

[0070] (1) Prepare a Cr(VI) aqueous solution with a concentration of 10 mg / L and pH = 2, and quantitatively detect the initial Cr(VI) concentration using the diphenylcarbazide spectrophotometric method (standard GB / T 7467-1987); (2) Place a membrane on a self-made dynamic membrane transfer device, pour 50 mL of a Cr(VI) aqueous solution with a concentration of 10 mg / L and pH = 2 into the device, and simultaneously use a light intensity of 200 mW / cm². 2 Xenon lamp irradiation was used to photoreduc Cr(VI);

[0071] (3) Take the solution after membrane treatment, measure the residual Cr(VI) concentration, and calculate the Cr(VI) removal rate.

[0072] Figure 5 Graphs showing the adsorption and photoreduction of Cr(VI) by the composite membranes prepared in all comparative examples and embodiments. Figure 5 It can be seen that the PANI / FeZr-MOF / PVDF membrane exhibits the best adsorption and photoreduction effects for Cr(VI), with an adsorption efficiency of 57.3% and a photoreduction efficiency of 80.0%. The improved adsorption efficiency is mainly attributed to the electrostatic adsorption of Cr(VI) by PANI, while the improved photoreduction efficiency is mainly attributed to the electrostatic adsorption of Cr(VI) by PANI and the photoreduction of Cr(VI) by FeZr-MOF.

[0073] Application Example 5: The composite membrane prepared in the example was applied to the separation of oil-water mixed emulsions.

[0074] (1) Prepare 100 mL of a mixed emulsion with an oil phase and an aqueous phase in a volume ratio of 1:99, wherein the oil phase consists of edible oil, petroleum ether, toluene and dichloromethane.

[0075] (2) Take a membrane and place it on the self-made dynamic membrane device. Pour 100 mL of a mixture of oil phase and water phase with a volume ratio of 1:99 into the device to perform oil-water separation.

[0076] (3) Take the aqueous phase after membrane separation, weigh it with a balance, and calculate the oil-water separation efficiency.

[0077] Figure 6 The image shows the effect of the composite membrane prepared for this example on separating different oil-water mixed emulsions. Figure 6 It can be seen that the PANI / FeZr-MOF / PVDF membrane has a good separation effect on different oil-water mixed emulsions, with a separation efficiency close to 100%, which is attributed to the superhydrophilic properties of the PANI / FeZr-MOF / PVDF membrane.

[0078] Finally, 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 foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a superhydrophilic composite membrane that can be used to remove multiple pollutants from water, characterized in that, The preparation steps include the following: FeZr-MOF, a bimetallic organic framework material, was prepared by a one-step solvothermal method. FeZr-MOF powder was dispersed in a suitable solvent and mixed well. Polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP) were added and stirred under a water bath at 30-80℃ to obtain a uniformly mixed casting solution. After ultrasonic degassing, FeZr-MOF / PVDF composite membrane was prepared by non-solvent phase separation (NIPS). Then, a polyaniline (PANI) coating is polymerized in situ on the surface of the composite membrane to obtain a PANI / FeZr-MOF / PVDF composite membrane.

2. The method for preparing a superhydrophilic composite membrane for removing multiple pollutants from water as described in claim 1, characterized in that: The preparation steps of the bimetallic organic framework material FeZr-MOF include: 2-Aminoterephthalic acid was dissolved in N,N-dimethylformamide, and ferric chloride hexahydrate and zirconium tetrachloride were added and mixed. The mixture was reacted at 100-150℃ for 24-48 h. After cooling to room temperature, the precipitate was collected, dried, and powdered bimetallic organic framework material FeZr-MOF was obtained.

3. The method for preparing a superhydrophilic composite membrane for removing multiple pollutants from water as described in claim 2, characterized in that: The molar ratio of ferric chloride hexahydrate, zirconium tetrachloride, 2-aminoterephthalic acid and N,N-dimethylformamide is (1-9):(1-9):10:(650-1000).

4. The method for preparing a superhydrophilic composite membrane for removing multiple pollutants from water as described in claim 1, characterized in that: When FeZr-MOF powder is dispersed in a suitable solvent, the suitable solvent is N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone.

5. The method for preparing a superhydrophilic composite membrane for removing multiple pollutants from water as described in claim 1, characterized in that: The mass ratio of FeZr-MOF powder, suitable solvent, PVDF, and PVP is (1-3):(45-50): 8.5:(1.5-2.5)。 6. The method for preparing a superhydrophilic composite membrane for removing multiple pollutants from water as described in claim 1, characterized in that: The specific steps of the NIPS method include: taking an appropriate amount of casting solution onto a glass plate, scraping it into a film using a 100-300μm film scraper, and then immersing it in a deionized water bath at room temperature to form a film.

7. The method for preparing a superhydrophilic composite membrane for removing multiple pollutants from water as described in claim 1, characterized in that: Steps for in-situ polymerization of PANI coating on FeZr-MOF / PVDF surface: A certain amount of aniline was added to a 0.5-2 mol / L protic acid solution, denoted as solution A; a certain amount of ammonium persulfate was weighed and dissolved in water, denoted as solution B; solutions A and B were mixed evenly, and FeZr-MOF / PVDF composite membrane was added, and the reaction was carried out at room temperature for more than 5 hours.

8. The method for preparing a superhydrophilic composite membrane for removing multiple pollutants from water as described in claim 7, characterized in that: The mass ratio of aniline, protic acid solution, ammonium persulfate and water is 1.87:(30-50):(0.046-0.69):(30-50).

9. A superhydrophilic composite membrane that can be used to remove multiple pollutants from water, characterized in that, The preparation method described in claims 1-8 can simultaneously remove multiple types of pollutants from water.

10. The application of the superhydrophilic composite membrane as described in claim 9, which can be used to remove multiple types of pollutants from water, in the field of water pollution control.

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