Self-cleaning oil-water separation membrane and preparation method and application thereof

Abstract

The application discloses a kind of self-cleaning oil-water separation membranes and preparation method and application thereof, method includes: using solvothermal method to prepare metal organic framework material;Using metal organic framework material, using in-situ deposition / precipitation method, AgI / UiO-66 (NH2) heterostructure nanomaterial is prepared;Using AgI / UiO-66 (NH2) heterostructure nanomaterial, using electrospinning method, AgI / UiO-66 (NH2) / PAN fiber membrane is prepared;Using atom transfer radical polymerization method, hydrophilic polymer brush is grafted to the surface of AgI / UiO-66 (NH2) / PAN fiber membrane, and the self-cleaning oil-water separation membrane is prepared;Hydration layer is formed on the surface of the film, which greatly reduces the adsorption and deposition of pollutants;It has higher separation flux, excellent oil-water separation efficiency and separation performance for different oil-in-water emulsions.

Description

Technical Field

[0001] This invention belongs to the field of oil-water separation technology, and specifically relates to a self-cleaning oil-water separation membrane, its preparation method, and its application. Background Technology

[0002] Based on the form in which oil exists in water, oil can be classified into free oil (>150μm), dispersed oil (20–150μm), and emulsified oil (<20μm). Free and dispersed oils are usually removed from water using traditional flotation or skimming methods, while emulsified oils are currently removed using membrane separation methods. However, in existing membrane separation technologies, irreversible fouling of oil-water separation membranes during the separation process leads to a decrease in separation flux, resulting in low separation efficiency. Summary of the Invention

[0003] In view of the technical problems existing in the prior art, the present invention provides a self-cleaning oil-water separation membrane, its preparation method and application, so as to solve the technical problem that the separation flux decreases and the separation efficiency is low in the existing membrane separation technology due to irreversible pollution of the oil-water separation membrane during the separation process.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] This invention provides a method for preparing a self-cleaning oil-water separation membrane, comprising the following steps:

[0006] Step 1: Prepare metal-organic framework material UiO-66(NH2) using a solvothermal method;

[0007] Step 2: Using the metal-organic framework material UiO-66(NH2), AgI / UiO-66(NH2) heterostructure nanomaterials are prepared by in-situ deposition / precipitation method;

[0008] Step 3: Using the AgI / UiO-66(NH2) heterostructure nanomaterial, an AgI / UiO-66(NH2) / PAN fiber membrane is prepared by electrospinning.

[0009] Step 4: Using atom transfer radical polymerization, a hydrophilic polymer is brush-grafted onto the surface of the AgI / UiO-66(NH2) / PAN fiber membrane to prepare the self-cleaning oil-water separation membrane.

[0010] Furthermore, the process of preparing the metal-organic framework material UiO-66(NH2) using the solvothermal method in step 1 is as follows:

[0011] Zirconium chloride, 2-aminoterephthalic acid, N,N-dimethylformamide and glacial acetic acid were mixed and ultrasonically vibrated to obtain a mixed solution;

[0012] The mixed solution was transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, it was naturally cooled to room temperature to obtain the hydrothermal reaction product.

[0013] The hydrothermal reaction product was centrifuged, and a pale yellow solid was collected.

[0014] After washing and drying the pale yellow solid, the metal-organic framework material UiO-66(NH2) was obtained.

[0015] Furthermore, in step 2, the process of preparing AgI / UiO-66(NH2) heterostructure nanomaterials using the metal-organic framework material UiO-66(NH2) via in-situ deposition / precipitation is as follows:

[0016] The metal-organic framework material UiO-66(NH2) was dispersed in water to obtain a UiO-66(NH2) dispersion.

[0017] Potassium iodide was added to the UiO-66(NH2) dispersion, and after stirring, silver nitrate aqueous solution was added dropwise to carry out an ion exchange reaction to obtain the ion exchange reaction product.

[0018] The ion exchange reaction product was centrifuged, washed, and dried to obtain AgI / UiO-66(NH2) heterostructure nanomaterials.

[0019] Furthermore, potassium iodide is added to the UiO-66(NH2) dispersion, and after stirring, silver nitrate aqueous solution is added dropwise to carry out an ion exchange reaction to obtain the ion exchange reaction product. The specific process is as follows:

[0020] Potassium iodide was added to the UiO-66(NH2) dispersion, and after stirring, silver nitrate aqueous solution was added dropwise using a constant pressure dropping funnel. The mixture was stirred at room temperature and in the dark to carry out an ion exchange reaction and obtain the ion exchange reaction product.

[0021] Furthermore, the process of preparing AgI / UiO-66(NH2) / PAN fiber membrane by electrospinning using the aforementioned AgI / UiO-66(NH2) heterostructure nanomaterial is as follows:

[0022] The AgI / UiO-66(NH2) heterostructure nanomaterial was added to DMF and stirred and sonicated until completely dispersed to obtain AgI / UiO-66(NH2) dispersion.

[0023] Polyacrylonitrile was added to the AgI / UiO-66(NH2) dispersion and stirred until the polyacrylonitrile was completely dissolved. The mixture was then placed in a vacuum oven to stand and remove air bubbles, thus obtaining the electrospinning solution.

[0024] Electrospinning was performed using the electrospinning solution to obtain an AgI / UiO-66(NH2) / PAN fiber membrane.

[0025] Further, step 4, the process of preparing the self-cleaning oil-water separation membrane by grafting a hydrophilic polymer onto the surface of the AgI / UiO-66(NH2) / PAN fiber membrane using an atom transfer radical polymerization method, is as follows:

[0026] Anhydrous tetrahydrofuran and the AgI / UiO-66(NH2) / PAN fiber membrane were placed in a reactor, and an initiator was added to carry out a polymerization reaction to obtain the polymerization product.

[0027] The polymerization product was placed in a mixed solvent of methanol and deionized water, and pentamethyldiethylenetriamine and methacryloxyethyl sulfobetaine were added. The mixture was stirred and degassed to obtain the pre-reaction mixed solution.

[0028] Cuprous bromide was added to the pre-reaction mixed solution, and an atom transfer radical polymerization reaction was carried out under a nitrogen atmosphere to obtain the transfer polymerization product.

[0029] The product of the transfer polymerization reaction is washed and dried to obtain the self-cleaning oil-water separation membrane.

[0030] Furthermore, the initiator is 2-bromo-2-methylpropionyl bromide.

[0031] The present invention also provides a self-cleaning oil-water separation membrane, which is prepared by the method described above.

[0032] The present invention describes the application of a self-cleaning oil-water separation membrane, which is used to separate oil from oily wastewater.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] This invention provides a self-cleaning oil-water separation membrane, its preparation method, and its application. A metal-organic framework material UiO-66(NH2) is prepared using a solvothermal method. The prepared UiO-66(NH2) is modified with silver iodide using an in-situ deposition / precipitation method to obtain an AgI / UiO-66(NH2) heterostructure nanomaterial with visible light photocatalytic performance. By adding the AgI / UiO-66(NH2) heterostructure nanomaterial to an electrospinning solution, a visible light-driven self-cleaning composite membrane substrate, AgI / UiO-66(NH2) / PAN fiber membrane, is prepared using electrospinning. The AgI / UiO-66(NH2) membrane is then polymerized using atom transfer radical polymerization. A superwetting, visible-light-driven self-cleaning oil-water separation membrane was prepared by combining heterostructured nanomaterials with pSBMA zwitterionic polymers. The prepared self-cleaning oil-water separation membrane has a substrate embedded with visible-light-catalyzed AgI / UiO-66(NH2) heterostructured nanomaterials, which effectively avoids membrane fouling during oil-water separation. Simultaneously, the self-cleaning oil-water separation membrane is grafted with the highly hydrophilic zwitterionic polymer brush pSBMA via atom transfer radical polymerization, forming a hydration layer on the membrane surface, significantly reducing pollutant adsorption and deposition. Furthermore, the oil-water separation composite membrane exhibits high separation flux, excellent oil-water separation efficiency, and good separation performance for various oil-in-water emulsions.

[0035] Furthermore, using PAN as the substrate for the separation membrane, AgI / UiO-66(NH2)NPs as visible light catalytic nanoparticles, pSBMA as a hydrophilic polymer brush, and 2-bromo-2-methylpropionyl bromide as an initiator, a superwetting visible light-driven self-cleaning oil-water separation membrane was prepared. The obtained superwetting visible light-driven self-cleaning oil-water separation membrane can separate different oil-in-water emulsions, providing new ideas and methods for the preparation of oil-water separation membranes and the antifouling performance of membranes. Attached Figure Description

[0036] Figure 1 The images shown are TEM images of the metal-organic framework material UiO-66(NH2) and the AgI / UiO-66(NH2) heterostructure nanomaterial in the examples; wherein, Figure 1 a and Figure 1 b are TEM images of the metal-organic framework material UiO-66(NH2); Figure 1 c and Figure 1 d are all TEM images of AgI / UiO-66(NH2) heterostructure nanomaterials;

[0037] Figure 2 Here is a SEM image of the AgI / UiO-66(NH2) / PAN fiber membrane in the example; wherein, Figure 2 The magnification of a is 30K;Figure 2 The magnification of b is 10K.

[0038] Figure 3 The infrared spectra of the AgI / UiO-66(NH2) / PAN fiber membrane and the self-cleaning oil-water separation membrane in the examples are shown below; curve a is the infrared spectrum curve of the AgI / UiO-66(NH2) / PAN fiber membrane; curve b is the infrared spectrum curve of the self-cleaning oil-water separation membrane.

[0039] Figure 4 This is a schematic diagram of the water contact angle of the AgI / UiO-66(NH2) / PAN fiber membrane in the embodiment;

[0040] Figure 5 This is a schematic diagram of the water contact angle of the self-cleaning oil-water separation membrane in the embodiment;

[0041] Figure 6 The X-ray diffraction patterns of the metal-organic framework material UiO-66(NH2) and the AgI / UiO-66(NH2) heterostructure nanomaterials in the examples are shown below; wherein, curve a is the X-ray diffraction pattern of the metal-organic framework material UiO-66(NH2), and curve b is the X-ray diffraction pattern of the AgI / UiO-66(NH2) heterostructure nanomaterials.

[0042] Figure 7 This is a bar chart showing the separation flux of the self-cleaning oil-water separation membrane in the embodiment;

[0043] Figure 8 The graph shows the photocatalytic performance of the self-cleaning oil-water separation membrane in the example. Detailed Implementation

[0044] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0045] This invention provides a method for preparing a self-cleaning oil-water separation membrane, comprising the following steps:

[0046] Step 1: The metal-organic framework material UiO-66(NH2) was prepared using a solvothermal method; the specific process for preparing the metal-organic framework material UiO-66(NH2) is as follows:

[0047] Zirconium chloride, 2-aminoterephthalic acid, N,N-dimethylformamide, and glacial acetic acid were mixed and ultrasonically vibrated to obtain a mixed solution. The mixed solution was transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a hydrothermal reaction product. The hydrothermal reaction product was centrifuged to collect a pale yellow solid. The pale yellow solid was washed and dried to obtain the metal-organic framework material UiO-66(NH2).

[0048] Step 2: Using the metal-organic framework material UiO-66(NH2), AgI / UiO-66(NH2) heterostructure nanomaterials are prepared by in-situ deposition / precipitation method; the specific process for preparing AgI / UiO-66(NH2) heterostructure nanomaterials is as follows:

[0049] The metal-organic framework material UiO-66(NH2) was dispersed in water to obtain a UiO-66(NH2) dispersion. Potassium iodide was added to the UiO-66(NH2) dispersion, and after stirring, silver nitrate aqueous solution was added dropwise using a constant pressure dropping funnel. The mixture was stirred at room temperature and in the dark to carry out an ion exchange reaction, yielding an ion exchange reaction product. The ion exchange reaction product was centrifuged, washed, and dried to obtain AgI / UiO-66(NH2) heterostructure nanomaterials. The AgI / UiO-66(NH2) heterostructure nanomaterials are silver iodide-modified metal-organic framework UiO-66(NH2) composite photocatalysts.

[0050] Step 3: Using the AgI / UiO-66(NH2) heterostructure nanomaterial, an AgI / UiO-66(NH2) / PAN fiber membrane is prepared by electrospinning; the specific process for preparing the AgI / UiO-66(NH2) / PAN fiber membrane is as follows:

[0051] The AgI / UiO-66(NH2) heterostructure nanomaterial was added to DMF and stirred and sonicated until completely dispersed to obtain an AgI / UiO-66(NH2) dispersion. Polyacrylonitrile was added to the AgI / UiO-66(NH2) dispersion and stirred until the polyacrylonitrile was completely dissolved. The mixture was then placed in a vacuum oven to remove air bubbles, resulting in an electrospinning solution. Electrospinning was performed using the electrospinning solution to obtain an AgI / UiO-66(NH2) / PAN fiber membrane.

[0052] Step 4: Using atom transfer radical polymerization (ATRP), a hydrophilic polymer brush is grafted onto the surface of the AgI / UiO-66(NH2) / PAN fiber membrane to prepare the self-cleaning oil-water separation membrane; wherein, the hydrophilic polymer brush is a hydrophilic zwitterionic polymer brush pSBMA.

[0053] The process of grafting the hydrophilic polymer onto the surface of the AgI / UiO-66(NH2) / PAN fiber membrane is as follows:

[0054] Anhydrous tetrahydrofuran and the AgI / UiO-66(NH2) / PAN fiber membrane were placed in a reactor, and an initiator was added to carry out a polymerization reaction to obtain a polymerization product; wherein the initiator was 2-bromo-2-methylpropionyl bromide; the polymerization product was placed in a mixed solvent of methanol and deionized water, and pentamethyldiethylenetriamine and methacryloylethyl sulfobetaine were added, and the mixture was stirred and degassed to obtain a pre-reaction mixed solution; cuprous bromide was added to the pre-reaction mixed solution, and an atom transfer radical polymerization reaction was carried out under a nitrogen atmosphere to obtain a transfer polymerization product; the transfer polymerization product was washed and dried to obtain the self-cleaning oil-water separation membrane.

[0055] Preparation principle:

[0056] The preparation method of the self-cleaning oil-water separation membrane of the present invention firstly prepares a metal-organic framework material UiO-66(NH2) by a solvothermal method; then, using an in-situ deposition / precipitation method, the prepared UiO-66(NH2) is modified with silver iodide to obtain an AgI / UiO-66(NH2) heterostructure nanomaterial with visible light photocatalytic performance; the prepared AgI / UiO-66(NH2) heterostructure nanomaterial is added to an electrospinning solution, and then an AgI / UiO-66(NH2) / PAN membrane is prepared by electrospinning; finally, a hydrophilic zwitterionic polymer brush pSBMA is grafted onto the surface of the composite membrane using the ATRP method; in this invention, the surface of the self-cleaning oil-water separation membrane contains UiO-66(NH2)NPs, and when the membrane performs oil-water emulsion separation, water molecules in the emulsion tend to... The pSBMA readily forms hydrogen bonds with the -NH2 in UiO-66-NH2, and the unique cage-like structure of MOF can easily capture and lock water molecules. It establishes a stable hydration layer on the membrane surface, preventing oil from penetrating into the membrane. Furthermore, due to the presence of AgI / UiO-66(NH2)NPs heterojunction material with visible light photocatalytic properties in the membrane substrate, self-cleaning performance can be achieved during oil-water separation. The loading of AgI / UiO-66(NH2)NPs generates a large number of submicron spheres on the fiber membrane surface, resulting in greater surface roughness. The greater roughness leads to a lower water contact angle, stronger hydrophilicity, and enhanced water flux. Using AgI / UiO-66(NH2)NPs as sites, zwitterionic pSBMA is grafted onto the AgI / UiO-66(NH2)NPs surface through in-situ growth using the ATRP method, further improving the wettability of the membrane.

[0057] Example

[0058] This embodiment provides a method for preparing a self-cleaning oil-water separation membrane, including the following steps:

[0059] Step 1: Prepare the metal-organic framework material UiO-66(NH2) using a solvothermal method; the specific preparation process of the metal-organic framework material UiO-66(NH2) is as follows:

[0060] 4 mmol of zirconium chloride and 4 mmol of BDC-NH2 were dissolved in a mixed solvent of 220 mL of LDMF and 80 mL of glacial acetic acid, and the solution was sonicated for 30 min to obtain a mixed solution.

[0061] The mixed solution was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and reacted at 120°C for 12 hours. After the reaction was completed, the hydrothermal reactor was naturally cooled to room temperature to obtain the hydrothermal reaction product.

[0062] The hydrothermal reaction product was centrifuged to collect a pale yellow solid. The pale yellow solid was washed three times with distilled water and methanol, respectively. Finally, it was dried at 60°C for 12 hours to obtain UiO-66(NH2) solid powder, which is the metal-organic framework material UiO-66(NH2).

[0063] Step 2: Using the metal-organic framework material UiO-66(NH2), AgI / UiO-66(NH2) heterostructure nanomaterials are prepared by in-situ deposition / precipitation method; wherein, the preparation process of the AgI / UiO-66(NH2) heterostructure nanomaterials is as follows:

[0064] Weigh 161.6 mg of the UiO-66(NH2) solid powder and add it to 35 mL of deionized water. Sonicate until completely dispersed to obtain UiO-66(NH2) dispersion.

[0065] Add 48.9 mg of potassium iodide solid to the UiO-66(NH2) dispersion, stir for 1 h, and then add 1.475 mL of 0.2 M silver nitrate aqueous solution dropwise using a constant pressure dropping funnel; stir for 12 h at room temperature and in the dark to carry out the ion exchange reaction and obtain the ion exchange reaction product.

[0066] The ion exchange reaction product was centrifuged and washed with deionized water and anhydrous ethanol three times to separate the solid material. The collected solid product was placed in a vacuum drying oven and dried at 60°C for 6 hours to obtain silver iodide modified metal-organic framework UiO-66(NH2) composite photocatalyst, that is, AgI / UiO-66(NH2) heterostructure nanomaterial.

[0067] Step 3: Using the AgI / UiO-66(NH2) heterostructure nanomaterial, an AgI / UiO-66(NH2) / PAN fiber membrane is prepared by electrospinning.

[0068] The process for preparing the AgI / UiO-66(NH2) / PAN fiber membrane is as follows:

[0069] 0.8 g of AgI / UiO-66(NH2) heterostructure nanomaterial was added to 8 mL of DMF, stirred and sonicated to completely disperse it, and AgI / UiO-66(NH2) dispersion was obtained.

[0070] 1.5 g of PAN powder was added to the AgI / UiO-66(NH2) dispersion, and stirring was continued until the PAN powder was completely dissolved. Finally, the mixture was allowed to stand in a vacuum oven to remove air bubbles, yielding an electrospinning solution. Electrospinning was performed using this solution to obtain an AgI / UiO-66(NH2) / PAN fiber membrane. The electrospinning process was carried out at room temperature and 70% humidity; the syringe injection speed was 0.5 mL / h. -1 The needle inner diameter was 0.7 mm, the receiving distance was 18 cm, the working voltage was 20 kV, the membrane collector speed was 200 rpm, the electrospinning time was 8 h, and the prepared AgI / UiO-66(NH2) / PAN fiber membrane was hot-pressed at 100℃ for 1 h and then stored for later use.

[0071] Step 4: Using the ATRP method, a hydrophilic polymer is grafted onto the surface of the AgI / UiO-66(NH2) / PAN fiber membrane through in-situ growth to prepare the self-cleaning oil-water separation membrane; the specific process for preparing the self-cleaning oil-water separation membrane is as follows:

[0072] 60 mL of anhydrous tetrahydrofuran and AgI / UiO-66(NH2) / PAN fiber membrane were placed in a reactor, and then 30 μL of 2-bromo-2-methylpropionyl bromide was added to carry out a polymerization reaction to obtain the polymerization product. The entire polymerization reaction was carried out at room temperature under N2 protection. After the reaction was completed, the unreacted initiator on the surface of the polymerization product was washed off with anhydrous ethanol, and the product was air-dried and stored for later use.

[0073] The polymerization product was placed in a mixed solvent of 30 mL methanol and 30 mL deionized water, and 60 μL pentamethyldiethylenetriamine and 1.2 g SBMA were added. The mixture was stirred and degassed twice to obtain a pre-reaction mixed solution. Then, 40 mg CuBr was added to the pre-reaction mixed solution, and the ATRP polymerization reaction was carried out at 60 °C under a nitrogen atmosphere for 24 h. After the reaction was completed, the membrane was washed three times with deionized water and ethanol, and then dried to obtain the self-cleaning oil-water separation membrane.

[0074] As attached Figure 1 As shown, attached Figure 1 The document provides TEM images of the metal-organic framework material UiO-66(NH2) and the AgI / UiO-66(NH2) heterostructure nanomaterials in the embodiments; wherein, Figure 1 a and Figure 1 b are TEM images of the metal-organic framework material UiO-66(NH2), from Figure 1 a and Figure 1 As can be seen from b, the particle size of the metal-organic framework material UiO-66(NH2) is about 200nm; Figure 1 c and Figure 1 d are all TEM images of AgI / UiO-66(NH2) heterostructure nanomaterials; from Figure 1 c and Figure 1 As can be seen from d, silver iodide was successfully modified on the surface of the metal-organic framework material UiO-66(NH2), which means that AgI / UiO-66(NH2) heterostructure nanomaterials with visible light photocatalytic properties were successfully prepared.

[0075] As attached Figure 2 As shown, attached Figure 2 The SEM images of the AgI / UiO-66(NH2) / PAN fiber membranes in the examples are given below; where, Figure 2 The magnification of a is 30K; Figure 2 The magnification of b is 10K; from the attached... Figure 2 As can be seen, submicron spheres exist on the fiber surface, which makes the surface roughness greater.

[0076] As attached Figure 3 As shown, attached Figure 3 The infrared spectra of the AgI / UiO-66(NH2) / PAN fiber membrane and the self-cleaning oil-water separation membrane are given in the appendix; curve a is the infrared spectrum of the AgI / UiO-66(NH2) / PAN fiber membrane; curve b is the infrared spectrum of the self-cleaning oil-water separation membrane; from the appendix... Figure 3 As can be seen from the infrared spectrum of the pSBMA-modified product, a value located at 1041 cm⁻¹ can be observed. -1 The asymmetric stretching vibration peak at O=S=O indicates that pSBMA was successfully grafted onto the surface of the composite membrane.

[0077] As attached Figure 4 , 5 As shown, attached Figure 4 The diagram shows the water contact angle of the AgI / UiO-66(NH2) / PAN fiber membrane. Figure 5 The diagram shows the water contact angle of the self-cleaning oil-water separator; from the attached...Figure 4 , 5 As can be seen, before modification, the water contact angle stabilized at ~31° for a period of time, while after modification, the water contact angle in the air became 0° in ~0.8 seconds, indicating that it has superwetting properties.

[0078] As attached Figure 6 As stated, Appendix Figure 6 The XRD pattern of the metal-organic framework material UiO-66(NH2) is given in the appendix. Figure 6 As can be seen, the metal-organic framework material UiO-66(NH2) exhibits obvious characteristic peaks, indicating that UiO-66(NH2) has good crystallinity. The characteristic peaks of AgI at 2θ values ​​of 23.7°, 39.2°, and 46.3° correspond to the {111}, {220}, and {311} crystal planes of β-cubic AgI (JCPDS No. 78-6041), respectively, while the characteristic peak at 2θ value of 22.3° corresponds to the {100} crystal plane of α-hexagonal AgI (JCPDS 09-0374).

[0079] As attached Figure 6 As stated, Appendix Figure 6 The X-ray diffraction patterns of the metal-organic framework material UiO-66(NH2) and the AgI / UiO-66(NH2) heterostructure nanomaterials are given in the figure; curve a is the X-ray diffraction pattern of the metal-organic framework material UiO-66(NH2), and curve b is the X-ray diffraction pattern of the AgI / UiO-66(NH2) heterostructure nanomaterials; from the appendix Figure 6 As can be seen, it contains characteristic peaks of UiO-66(NH2) and AgI, indicating that the structure of UiO-66(NH2)NPs was not destroyed during material composite, and AgI / UiO-66(NH2) heterostructure nanomaterials were successfully prepared.

[0080] As attached Figure 7 As shown, attached Figure 7 Bar charts showing the separation flux of the self-cleaning oil-water separator in four different oil-in-water emulsions: toluene / water, dichloroethane / water, petroleum ether / water, and n-hexane / water. The separation fluxes were 239.7 L / m³, respectively. -2 h -1 1535.0L m -2 h -1 835.1L m -2 h -1 and 141.7L m -2 h -1 No additional pressure was introduced during the above flux tests; the tests were conducted solely under gravity. It can be seen that the fluxes of the four oil-in-water emulsions differed significantly, mainly due to the properties of the oil itself.

[0081] As attached Figure 8 As shown, attached Figure 8 Photocatalytic performance curves of the self-cleaning oil-water separator; from the attached... Figure 8 As can be seen, the photocatalytic performance of the composite membrane was evaluated by degrading MB, using a 300W visible light source to simulate sunlight; before irradiation, the membrane was immersed in a solution containing MB (10 mg / L). -1 In a solution of 50 mL, the solution was first isolated from light for 30 minutes to allow it to reach adsorption equilibrium. Then, 4 mL of the solution was taken out at fixed time intervals, and the concentration of methylene blue was measured at the maximum absorption wavelength of 664 nm using a UV-Vis spectrophotometer. It can be seen that after irradiation for the preset time, the residual concentration of MB decreased significantly.

[0082] In this invention, AgI / UiO-66(NH2) heterostructure nanomaterials are combined with polymethacryloylethyl sulfobetaine (pSBMA), which improves the hydrophilicity of the membrane and also enables the composite membrane to self-clean under light-driven conditions.

[0083] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for preparing a self-cleaning oil-water separation membrane, characterized in that, Includes the following steps: Step 1: Prepare metal-organic framework material UiO-66(NH2) using a solvothermal method; Step 2: Using the metal-organic framework material UiO-66(NH2), AgI / UiO-66(NH2) heterostructure nanomaterials are prepared by in-situ deposition / precipitation method; Step 3: Using the AgI / UiO-66(NH2) heterostructure nanomaterial, an AgI / UiO-66(NH2) / PAN fiber membrane is prepared by electrospinning. Step 4: Using atom transfer radical polymerization, a hydrophilic polymer is brush-grafted onto the surface of the AgI / UiO-66(NH2) / PAN fiber membrane to prepare the self-cleaning oil-water separation membrane; In step 2, the AgI / UiO-66(NH2) heterostructure nanomaterials are prepared using the metal-organic framework material UiO-66(NH2) via in-situ deposition / precipitation, as detailed below: The metal-organic framework material UiO-66(NH2) was dispersed in water to obtain a UiO-66(NH2) dispersion. Potassium iodide was added to the UiO-66(NH2) dispersion, and after stirring, silver nitrate aqueous solution was added dropwise to carry out an ion exchange reaction to obtain the ion exchange reaction product. The ion exchange reaction products were centrifuged, washed, and dried to obtain AgI / UiO-66(NH2) heterostructure nanomaterials. Step 3 involves preparing the AgI / UiO-66(NH2) / PAN fiber membrane using the AgI / UiO-66(NH2) heterostructure nanomaterial via electrospinning, as detailed below: The AgI / UiO-66(NH2) heterostructure nanomaterial was added to DMF and stirred and sonicated until completely dispersed to obtain AgI / UiO-66(NH2) dispersion. Polyacrylonitrile was added to the AgI / UiO-66(NH2) dispersion and stirred until the polyacrylonitrile was completely dissolved. The mixture was then placed in a vacuum oven to stand and remove air bubbles, thus obtaining the electrospinning solution. Electrospinning was performed using the electrospinning solution to obtain an AgI / UiO-66(NH2) / PAN fiber membrane; Step 4: The process of preparing the self-cleaning oil-water separation membrane by grafting a hydrophilic polymer onto the surface of the AgI / UiO-66(NH2) / PAN fiber membrane using atom transfer radical polymerization is as follows: Anhydrous tetrahydrofuran and the AgI / UiO-66(NH2) / PAN fiber membrane were placed in a reactor, and an initiator was added to carry out a polymerization reaction to obtain the polymerization product. The polymerization product was placed in a mixed solvent of methanol and deionized water, and pentamethyldiethylenetriamine and methacryloxyethyl sulfobetaine were added. The mixture was stirred and degassed to obtain the pre-reaction mixed solution. Cuprous bromide was added to the pre-reaction mixed solution, and an atom transfer radical polymerization reaction was carried out under a nitrogen atmosphere to obtain the transfer polymerization product. The transfer polymerization product is washed and dried to obtain the self-cleaning oil-water separation membrane; The initiator is 2-bromo-2-methylpropionyl bromide.

2. The method for preparing a self-cleaning oil-water separation membrane according to claim 1, characterized in that, In step 1, the process of preparing the metal-organic framework material UiO-66(NH2) using the solvothermal method is as follows: Zirconium chloride, 2-aminoterephthalic acid, N,N-dimethylformamide and glacial acetic acid were mixed and ultrasonically vibrated to obtain a mixed solution; The mixed solution was transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, it was naturally cooled to room temperature to obtain the hydrothermal reaction product. The hydrothermal reaction product was centrifuged, and a pale yellow solid was collected. After washing and drying the pale yellow solid, the metal-organic framework material UiO-66(NH2) was obtained.

3. The method for preparing a self-cleaning oil-water separation membrane according to claim 1, characterized in that, The process of adding potassium iodide to the UiO-66(NH2) dispersion, stirring, and then adding silver nitrate aqueous solution dropwise to carry out an ion exchange reaction and obtain the ion exchange reaction product is as follows: Potassium iodide was added to the UiO-66(NH2) dispersion, and after stirring, silver nitrate aqueous solution was added dropwise using a constant pressure dropping funnel. The mixture was stirred at room temperature and in the dark to carry out an ion exchange reaction and obtain the ion exchange reaction product.

4. A self-cleaning oil-water separation membrane, characterized in that, The self-cleaning oil-water separation membrane is prepared using the preparation method of the self-cleaning oil-water separation membrane as described in any one of claims 1-3.

5. The application of the self-cleaning oil-water separation membrane as described in claim 4, characterized in that, The self-cleaning oil-water separation membrane is used to separate oil from oily wastewater.

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