Preparation method of MOFs / PAN separation membrane with under-liquid super-amphiphobicity

Abstract

This invention discloses a method for preparing a MOFs / PAN separation membrane with underwater superhydrophobicity, comprising the following steps: Step 1, preparation of MOFs; the MOFs are one of t-ZIF-8, UIO-66-(COOH)2, β-CD-MOF(UIO-66-NH2), Cu-MOF, MOF-5@HAP, or MIL-101(Fe)@CNT; Step 2, melting a fusible polyacrylonitrile copolymer, a composite diluent, and the MOFs obtained in Step 1 to form a homogeneous casting solution; Step 3, using the casting solution obtained in Step 2 to prepare a MOFs / PAN separation membrane with underwater superhydrophobicity via a thermally induced phase separation method. In this invention, the MOFs form hydrogen bonds and π-π stacking interactions with the PAN matrix, making the MOFs less prone to detachment during long-term operation; the MOFs / PAN oil-water separation microporous membrane exhibits negative charge, adjustable pore size, excellent hydrophilicity, and good cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of oil-water separation membrane technology, specifically a method for preparing a MOFs / PAN separation membrane with underwater superhydrophobicity. Background Technology

[0002] In recent years, the discharge of industrial and domestic wastewater and frequent oil spills have posed increasingly serious threats to ecosystems and human health. Developing economical and effective strategies for treating oily wastewater and rationally recycling it is not only beneficial to economic and social development but also to the environment and human health. Membrane separation technology has gained increasing attention from researchers due to its advantages, including being green, environmentally friendly, efficient, and easy to operate, and its ability to effectively treat emulsified oily wastewater containing surfactants.

[0003] Application No. 2025103135210 discloses an inorganic hydrogel / polyvinylidene fluoride (PVDF) oil-water separation membrane, its preparation method, and its application. The membrane is prepared by sequentially immersing it in anhydrous ethanol, an alkaline solution, a tannic acid solution, a FeCl3·6H2O solution, and (NH4)6Mo7O. 24 An inorganic hydrogel / polyvinylidene fluoride (PVDF) oil-water separation membrane was obtained by immersion in a 4H₂O solution. The PVDF / TA / Gel composite membrane exhibits good biocompatibility and a simple preparation process; it also possesses strong hydrophilicity, underwater superoleophobic properties, antifouling characteristics, and good oil-water emulsion separation efficiency. However, limited by its single wetting characteristic, traditional oil-water separation membranes can only effectively treat specific types of oil-water emulsions (O / W or W / O). This limitation makes it difficult to handle oily wastewater with varying compositions, increasing separation costs and process complexity.

[0004] Application No. 2025101259721 discloses a method for preparing and applying a gel with superlipophilic-superhydrophobic properties under oil and an oil-water separation membrane. The gel material uses cyclodextrin acrylate as a crosslinking agent, acrylate as a monomer, and nonwoven fabric as a substrate material, forming a cyclodextrin polyacrylate coating through polymerization on the outer layer of the substrate. This composite membrane exhibits excellent air-to-oil-to-water-to-oil-to-water properties, making it suitable for separating water-in-oil emulsions. However, the single wettability of this oil-water separation membrane limits its application to only a single type of oil-water emulsion, severely restricting its use in treating different types of oily wastewater, and increasing the complexity and cost of the process. To expand the applicability of oil-water separation membranes in engineering practice, there is an urgent need for an oil-water separation membrane with switchable surface wettability.

[0005] Patent application number 2024119880350 discloses a method for preparing and applying a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane. PVDF is used as the base membrane, which is inexpensive, has good mechanical properties, is environmentally friendly, and has good recyclability. Iron ions (Fe...) are used... 3+ A dual autocatalytic system was constructed using PDMAPAA@TA-APTES@PVDF and tannic acid (TA) to rapidly, efficiently, and on a large scale prepare PDMAPAA@TA-APTES@PVDF composite hydrogel membranes under mild conditions. The prepared PDMAPAA@TA-APTES@PVDF composite hydrogel membranes exhibit high flux, superhydrophilicity, underwater superoleophobicity, and long-term stable antifouling properties. However, since they can only achieve oil-in-water emulsion separation, this severely limits the large-scale application of oil-water separation membranes with switchable surface wettability.

[0006] Therefore, there is an urgent need to develop an oil-water separation membrane material that is simple to process, has high separation efficiency, and can quickly switch surface wettability. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing a MOFs / PAN separation membrane with underwater superhydrophobicity.

[0008] The technical solution of this invention to solve the aforementioned technical problem is to provide a method for preparing a MOFs / PAN separation membrane with underwater superhydrophobicity, characterized in that the method includes the following steps: Step 1: Preparation of MOFs; The MOFs are one of t-ZIF-8, UIO-66-(COOH)2, β-CD-MOF(UIO-66-NH2), Cu-MOF, MOF-5@HAP or MIL-101(Fe)@CNT; Step 2, Preparation of casting solution: Melt the fusible polyacrylonitrile copolymer, composite diluent and MOFs obtained in step 1 to form a homogeneous casting solution; Step 3: Preparation of MOFs / PAN separation membrane with underwater superhydrophobicity: MOFs / PAN separation membrane with underwater superhydrophobicity is prepared by thermally induced phase separation using the casting solution obtained in Step 2.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The particle size of MOFs in this invention is 40~150nm, and they form hydrogen bonds and π-π stacking with the PAN matrix. MOFs are not easy to fall off during long-term operation. The MOFs / PAN oil-water separation microporous membrane is negatively charged, has adjustable pore size, excellent hydrophilicity, and good cycle stability.

[0010] (2) Compared with conventional PAN membranes, the MOFs / PAN separation membrane of the present invention has a superhydrophilic surface due to its underwater superhydrophobicity. The preparation process is more environmentally friendly, has high preparation efficiency, and is easy to scale up.

[0011] (3) The MOFs / PAN separation membrane with liquid-based superhydrophobicity of the present invention has higher wetting ability. The loading of MOFs improves the roughness and micro / nano structure of MOFs / PAN oil-water separation microporous membrane, and enhances the capillary effect on the membrane surface. At the same time, when water or oil is pre-wetted, water or oil molecules are adsorbed in the cavity of MOFs or on the surface of MOFs through capillary effect. The synergistic effect of MOFs and PAN-based microporous membrane endows PAN-based oil-water separation microporous membrane with liquid-based superhydrophobicity.

[0012] (4) Only water or oil is needed to pre-wet the surface of the MOFs / PAN separation membrane with superhydrophobic properties under liquid. This allows for rapid switching of surface wettability, preventing the intrusion of oil and water droplets, and giving the microporous membrane superhydrophobic properties under water or under oil. This enables on-demand switching and efficient separation of water-in-oil or oil-in-water emulsions.

[0013] (5) The process of this invention is simple and controllable. The prepared MOFs / PAN oil-water separation microporous membrane has good separation performance for different types of emulsions and has potential application prospects in the field of oil-water separation. It can be applied to large-scale industrial production. Attached Figure Description

[0014] Figure 1 The image is a ZIF-8 SEM image of Embodiment 1 of the present invention; Figure 2 The SEM image of t-ZIF-8 prepared in Example 1 of this invention; Figure 3 XRD curves of ZIF-8 and t-ZIF-8 prepared in Example 1 of the present invention, t-ZIF-8-1 of Comparative Example 3 and t-ZIF-8-2 of Comparative Example 4; Figure 4 The FT-IR curve of t-ZIF-8 prepared in Example 1 of this invention; Figure 5 This is a SEM image of the t-ZIF-8 / PAN separation membrane prepared in Example 1 of the present invention; Figure 6 SEM image of the hydrophilic PAN separation membrane prepared in Comparative Example 1 of this invention; Figure 7 This is a SEM image of the t-ZIF-8 / PAN separation membrane prepared in Comparative Example 2 of this invention; Figure 8The image shows the underwater contact angle of the t-ZIF-8 / PAN separation membrane prepared in Example 1 of this invention. Figure 9 This is a diagram showing the underwater contact angle of the hydrophilic PAN separation membrane prepared in Comparative Example 1 of this invention; Figure 10 The graph shows the separation performance of the t-ZIF-8 / PAN separation membrane prepared in Example 1 of this invention for oil-in-water emulsions. Figure 11 The graph shows the separation performance of the t-ZIF-8 / PAN separation membrane prepared in Example 1 of this invention for oil-water emulsions. Figure 12 Optical photographs of oil-in-water and water-in-oil emulsions before and after separation using the t-ZIF-8 / PAN separation membrane prepared in Example 1 of this invention. Detailed Implementation

[0015] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention in detail and do not limit the scope of protection of the present invention.

[0016] This invention provides a method for preparing a MOFs / PAN separation membrane with underwater superhydrophobicity (hereinafter referred to as the method), characterized in that the method includes the following steps: Step 1: Preparation of MOFs; The MOFs are one of t-ZIF-8, UIO-66-(COOH)2, β-CD-MOF(UIO-66-NH2), Cu-MOF, MOF-5@HAP or MIL-101(Fe)@CNT; Preferably, in step 1, the preparation method of t-ZIF-8 is as follows: ZIF-8 particles are uniformly dispersed in deionized water to obtain a uniformly dispersed ZIF-8 suspension; then, TA (tannic acid) solution is added to the ZIF-8 suspension to carry out the reaction; after the reaction is completed, the solid is separated by centrifugation; the solid is washed to remove unreacted TA and generated soluble impurities (such as free zinc ions); and after drying to constant weight, t-ZIF-8 is obtained. ZIF-8 particles were prepared according to the method described in patent document application number 202311541481.2; The process for uniform dispersion is as follows: ultrasonic method is used, with the temperature at room temperature (i.e., 20~30℃), ultrasonic power at 120~240W, ultrasonic frequency at 40kHz, and ultrasonic time at 0.5~1h. The concentration of the TA solution is 3~20 g / L (preferably 10 g / L), the mass ratio of ZIF-8 particles to deionized water is 1:50~200 (preferably 1:100), and the volume ratio of ZIF-8 suspension to TA solution is 1:0.5~2 (preferably 1:1). The reaction process is as follows: stirring is used at a speed of 700-950 rpm for a reaction time of 10-30 min (preferably 10 min) at room temperature; preferably, it is carried out in a magnetic stirrer. The centrifugation process is as follows: rotation speed 8000~10000 r / min, time 10~30 min; Deionized water is used for washing.

[0017] Preferably, in step 1, UIO-66-(COOH)2 is prepared according to the method in the patent document with application number 202510131019.8.

[0018] Preferably, in step 1, the preparation method of β-CD-MOF(UIO-66-NH2) is as follows: MOF(UIO-66-NH2) and β-cyclodextrin are uniformly dispersed in deionized water to obtain a β-CD-MOF(UIO-66-NH2) suspension, and the solid is separated by centrifugation to obtain β-CD-MOF(UIO-66-NH2); MOF(UIO-66-NH2) was prepared according to the method described in patent document application number 202510918710.0; The mass ratio of MOF(UIO-66-NH2) to β-cyclodextrin is 1~2:0.25~1 (preferably 1:1), and the ratio of the sum of the masses of MOF(UIO-66-NH2) and β-cyclodextrin to the volume of deionized water is 1g:50~200ml (preferably 1g:100ml). The process for uniform dispersion is as follows: ultrasonic method is used, with ultrasonic power of 120~240W, ultrasonic frequency of 40kHz, and ultrasonic time of 0.5~1h. The centrifugation process is: 8000~10000r / min, centrifugation time is 10~30min.

[0019] Preferably, in step 1, Cu-MOF is prepared according to the method described in the patent document with application number 202311512925.X.

[0020] Preferably, in step 1, the preparation method of MOF-5@HAP is as follows: pre-dried HAP (hydroxyapatite) and MOF-5 are uniformly dispersed in DMF, and then stirred to achieve uniform loading of MOF-5 on the surface of HAP to obtain the product; then the product is first washed with DMF, then washed with methanol for solvent exchange, and then activated to constant weight to obtain MOF-5@HAP; MOF-5 was prepared according to the method described in patent document application number 202410159133.7; The process for uniform dispersion is as follows: each component is completely dispersed in the solvent by ultrasound, with an ultrasound power of 120~240W, an ultrasound frequency of 40kHz, an ultrasound time of 0.5~1h, and a temperature of 70~80℃. The mass ratio of MOF-5 to HAP is 1~4:1 (preferably 4:1); the ratio of the sum of the masses of MOF-5 and HAP to the volume of DMF is 1g:50~200ml (preferably 1g:100ml). The stirring process is as follows: temperature 70~80℃, rotation speed 600~800r / min, time 12~24h; The activation process is as follows: temperature is 100~120℃, time is 12~24h; preferably carried out in a vacuum drying oven with a vacuum degree of less than -0.09MPa.

[0021] Preferably, in step 1, the preparation method of MIL-101(Fe)@CNT is as follows: CNT-COOH is uniformly dispersed in a mixed solvent of ethanol and DMF to obtain a CNT-COOH suspension; dried MIL-101(Fe) powder is uniformly dispersed in a mixed solvent of ethanol and DMF to obtain a MIL-101(Fe) suspension; then the MIL-101(Fe) suspension is slowly added dropwise to the CNT-COOH suspension, and stirred at room temperature until uniform to obtain a mixture; then the mixture is centrifuged at low speed to remove unbound large agglomerates, the precipitate is collected and washed with ethanol or DMF to remove loose particles and residual solvent, and after drying, self-assembled MIL-101(Fe)@CNT is obtained; MIL-101(Fe) was prepared according to the method described in patent document application number 202510723173.4; The process for uniform dispersion is as follows: ultrasonic method is used, with ultrasonic power of 120~240W, ultrasonic frequency of 40kHz, and ultrasonic time of 10~30min. The mass ratio of MIL-101(Fe) to CNT-COOH is 5~20:1 (preferably 10:1); the solid-liquid ratio of the CNT-COOH suspension is 0.1g:50~200ml (preferably 0.1g:100ml); the solid-liquid ratio of the MIL-101(Fe) suspension is 1g:50~200ml (preferably 1g:100ml); the volume ratio of ethanol to DMF is 1~2:1~2. The process for low-speed centrifugation is as follows: the rotation speed is 2000~4000 rpm, and the time is 5~10 min; The drying process is as follows: temperature 80~100℃, time 4~6h.

[0022] Step 2, Preparation of casting solution: Melt the fusible polyacrylonitrile copolymer, composite diluent and MOFs obtained in step 1 to form a homogeneous casting solution; Preferably, in step 2, the fusible polyacrylonitrile-based copolymer is prepared by the method of step S1 in patent document application number 202110159952.8.

[0023] Preferably, in step 2, the composite diluent consists of a primary diluent and a secondary diluent, with the primary diluent accounting for 50-100% of the total mass of the composite diluent; the primary diluent is one of caprolactam, ethylene carbonate, or diphenyl carbonate (preferably caprolactam); the secondary diluent is one of polyvinyl alcohol, glycerol, or triacetin (preferably triacetin). Preferably, in step 2, the mass of the fusible polyacrylonitrile copolymer is 15-35% of the mass of the composite diluent; the mass of the MOFs is 10-30% (preferably 5%) of the mass of the fusible polyacrylonitrile copolymer.

[0024] Preferably, in step 2, the melting process is as follows: stirring is used until all components are completely melted in an oxygen-free environment, the stirring speed is 400~800 rpm, the stirring time is 1~4 hours, and the stirring temperature is 150~200℃. Preferably, this is carried out in a magnetic stirrer.

[0025] Preferably, in step 2, the oxygen-free environment is an inert gas environment or a nitrogen environment (preferably a nitrogen environment), and the inert gas is argon or helium.

[0026] Step 3: Preparation of MOFs / PAN separation membrane with underwater superhydrophobicity: MOFs / PAN separation membrane with underwater superhydrophobicity is prepared by thermally induced phase separation (TIPS) using the casting solution obtained in Step 2.

[0027] Preferably, in step 3, the thermally induced phase separation method specifically involves: transferring the casting solution to an environment at 150~200℃ and holding it at that temperature for 10~20 minutes to allow the casting solution to flow; then transferring it to an air bath at 25~30℃ for 6~8 hours to allow the casting solution to undergo phase separation and solidification; after complete solidification, immersing it in deionized water for 24~48 hours to remove the composite diluent, and then drying it at 40~80℃ for 4~8 hours to constant weight to obtain a MOFs / PAN separation membrane with underwater superhydrophobicity.

[0028] The testing method in the embodiment is as follows: Underwater superhydrophobicity test: Immerse the prepared sample in oil or water, and after it is completely wetted, drop a 2μL drop (water drop or oil drop) onto the membrane surface. When the drop is stable, record the contact angle at this time, which is the oil-water contact angle and the water-oil contact angle.

[0029] Oil-water separation performance test: An experiment was conducted to separate an oil-water emulsion using terminal filtration at 0.04 MPa. The flux and efficiency of the oil-water separation were calculated using the following formula:

[0030]

[0031] In the formula, J w V, A, t, ΔP, c0, and c represent the membrane flux (L / m³). 2 (·h·bar), filtrate volume (L), effective membrane area (m²) 2 The parameters included running time (h), transmembrane pressure (bar), the content of dispersed phase in the emulsion, and the content of dispersed phase in the corresponding filtrate. For water-in-oil and oil-in-water emulsions, the water and oil contents were measured using a Karl Fischer titrator and a total organic carbon analyzer (Shimadzu TOC-LCPN), respectively.

[0032] Example 1: (1) 1g of ZIF-8 powder was sonicated with 100ml of deionized water at 180W and 40kHz for 45min at room temperature to obtain a uniformly dispersed ZIF-8 suspension; then 10g / L and 100ml of TA solution were added to the ZIF-8 suspension and stirred at 800rpm for 20min at room temperature; after the reaction was completed, the solid was separated by centrifugation at 8000r / min for 10min, washed with deionized water, and dried to constant weight to obtain t-ZIF-8; (2) 8g of fusible polyacrylonitrile copolymer, 1.2g of t-ZIF-8 and 40g of composite diluent (35g of caprolactam and 5g of triacetylglycerol) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 20 min. Then it was transferred to an air bath at 25°C for 7 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 36 h to remove the composite diluent. Then it was dried at 60°C for 6 h to obtain the t-ZIF-8 / PAN separation membrane with liquid-borne superhydrophobicity.

[0033] Depend on Figure 2 It can be seen that the t-ZIF-8 of Example 1 exhibits a uniform spherical structure with a size range of 20~150nm.

[0034] Depend on Figure 3It can be seen that the characteristic diffraction peaks appearing at 7.4°, 10.4°, 12.7°, and 18.0° correspond to the (011), (022), (112), and (222) crystal planes of the ZIF-8 material, respectively. (From...) Figure 4 It can be seen that at 1701cm -1 A distinct carbon-oxygen stretching of the carbonyl group is observed at 1571.3 cm. -1 A distinct benzene ring skeletal vibration was observed at 3300 cm⁻¹, compared to the spectrum of ZIF-8. -1 The newly appearing broad absorption peak is the stretching vibration peak of OH, at 1353 cm⁻¹. -1 The new absorption peak at the point is an in-plane bending vibration peak of OH, indicating that tannic acid successfully etched ZIF-8. Figure 3 and Figure 4 This demonstrates the successful synthesis of ZIF-8 and t-ZIF-8.

[0035] Depend on Figure 5 It can be seen that the surface of the t-ZIF-8 / PAN separation membrane is uniformly covered with t-ZIF-8, compared with the hydrophilic PAN separation membrane of Comparative Example 1 ( Figure 6 This demonstrates the successful preparation of the t-ZIF-8 / PAN separation membrane.

[0036] Depend on Figure 8 It can be seen that the underwater oil contact angle of the t-ZIF-8 / PAN separation membrane is 157.2° and the underwater water contact angle is 163.0°. Therefore, the t-ZIF-8 / PAN separation membrane has underwater superhydrophobicity.

[0037] Depend on Figure 10 and Figure 11 It can be seen that the separation flux and separation efficiency for oil-in-water and water-in-oil emulsions without emulsifiers are 5746 L / m³, respectively. -2 h·bar, 98.6% and 8133 L / m -2 With a separation throughput of 98.0% or higher, the separation flux and separation efficiency for oil-in-water and water-in-oil emulsions containing emulsifiers are 1200 L / m³. -2 h·bar, 98.2% and 2100 L / m -2 ·h·bar, 97.4% or higher.

[0038] Depend on Figure 12 As can be seen, no droplets were observed in the separated filtrate, indicating that it has excellent separation performance.

[0039] Comparative Example 1: (1) 8g of fusible polyacrylonitrile copolymer and 40g of composite diluent (including 35g caprolactam and 5g triacetin) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (2) Quickly pour the casting solution into a double-layer glass mold and clamp the glass with clamps. Then transfer the mold to an oven at 180°C for 20 minutes. Then transfer it to an air bath at 25°C for 7 hours to allow the casting solution to undergo phase separation and solidification. After complete solidification, remove the mold, soak the membrane in deionized water for 36 hours to remove the composite diluent, and then dry it at 60°C for 6 hours to obtain a hydrophilic PAN separation membrane.

[0040] Depend on Figure 6 It can be seen that the hydrophilic PAN separation membrane of Comparative Example 1 exhibits a typical bicontinuous network structure.

[0041] Testing showed that the underwater oil contact angle of the membrane was 82.6°, and the oil-water contact angle was 98.2°. Therefore, the hydrophilic PAN separation membrane does not possess underwater superaperophobicity. Figure 9 As shown, the separation flux and separation efficiency for oil-in-water and water-in-oil emulsions without emulsifiers are 3412 L / m³, respectively. -2 h·bar, 42.1% and 3514 L / m -2 With a concentration of 43.1% or higher, the separation flux and separation efficiency for oil-in-water and water-in-oil emulsions containing emulsifiers were 814 L / m³. -2 h·bar, 25.4% and 1049 L / m -2 • h·bar, 21.5% or more. Therefore, the hydrophilic PAN separation membrane of Comparative Example 1 does not have the ability to separate oil and water.

[0042] Comparative Example 2: (1) 1g of ZIF-8 powder was sonicated with 100ml of deionized water at 180W and 40kHz for 45min at room temperature to obtain a uniformly dispersed ZIF-8 suspension; then 10g / L and 100ml of TA solution were added to the ZIF-8 suspension and stirred at 800rpm for 20min at room temperature; after the reaction was completed, the solid was separated by centrifugation at 8000r / min for 10min, washed with deionized water, and dried to constant weight to obtain t-ZIF-8; (2) 15g of fusible polyacrylonitrile copolymer, 4.5g of t-ZIF-8 and 45g of composite diluent (including 25g of caprolactam and 20g of triacetylglycerol) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 20 min. Then it was transferred to an air bath at 25°C for 7 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 36 h to remove the composite diluent. Then it was dried at 60°C for 6 h to obtain the t-ZIF-8 / PAN separation membrane with liquid-borne superhydrophobicity.

[0043] Tests showed that the underwater oil contact angle of Comparative Example 2 was 167.8°, and the oil-water contact angle was 172.4°, thus exhibiting underwater superhydrophobicity. The separation flux and separation efficiency for emulsions without emulsifiers (both oil-in-water and water-in-oil types) were 2487 L / m³. -2 h·bar, 99.5% and 3175 L / m -2 With a separation flux of 387 L / m³ and a separation efficiency of over 99.6% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively above 99.6%. -2 h·bar, 99.8% and 475 L / m -2 • h·bar, 99.4% or higher. Excessive t-ZIF-8 loading severely clogs the pores of the PAN-based microporous membrane, such as… Figure 7 As shown, this causes a significant decrease in separation flux.

[0044] Comparative Example 3: Completely identical to Example 1, except that in step (1), the mixture was stirred at 800 rpm for 50 min at room temperature to obtain t-ZIF-8-1; Depend on Figure 3 It can be seen that the typical crystal structure of t-ZIF-8-1 disappears, indicating that the framework of ZIF-8 collapses after the etching time is extended.

[0045] Testing showed that the underwater oil contact angle of the t-ZIF-8-1 / PAN separation membrane was 83.6°, and the underwater water contact angle was 98.8°. Therefore, the t-ZIF-8-1 / PAN separation membrane does not possess underwater superhydrophobicity. The separation flux and efficiency for oil-in-water and water-in-oil emulsions without emulsifiers were 3518 L / m³, respectively. -2 h·bar, 41.1% and 3645 L / m -2 With a concentration of 42.8% or higher, the separation flux and separation efficiency for oil-in-water and water-in-oil emulsions containing emulsifiers are 883 L / m³, respectively. -2 h·bar, 26.1% and 1092 L / m -2 The concentration of 21.1% or higher (·h·bar) indicates that the t-ZIF-8-1 / PAN separation membrane does not have the ability to separate oil and water.

[0046] Comparative Example 4: It is exactly the same as Example 1, except that in step (1), the concentration of the TA solution is 40 g / L, and t-ZIF-8-2 is obtained; Depend on Figure 3 It can be seen that the typical crystal structure of t-ZIF-8-2 disappears, indicating that increasing the TA concentration will also cause the framework of ZIF-8 to collapse.

[0047] Testing showed that the underwater oil contact angle of the t-ZIF-8-2 / PAN separation membrane was 82.5°, and the underwater water contact angle was 97.4°. Therefore, the t-ZIF-8-1 / PAN separation membrane does not possess underwater superhydrophobicity. The separation flux and efficiency for oil-in-water and water-in-oil emulsions without emulsifiers were 3312 L / m³, respectively. -2 h·bar, 40.2% and 3454 L / m -2 With a concentration of 41.6% or higher, the separation flux and separation efficiency for oil-in-water and water-in-oil emulsions containing emulsifiers are 746 L / m³, respectively. -2 h·bar, 25.3% and 994 L / m -2 The concentration is above 20.8% (h·bar). Therefore, the t-ZIF-8-2 / PAN separation membrane does not have the ability to separate oil and water.

[0048] Example 2: (1) 0.5g of ZIF-8 powder was sonicated with 100ml of deionized water at 120W and 40kHz for 30min at room temperature to obtain a uniformly dispersed ZIF-8 suspension; then 10g / L and 100ml of TA solution were added to the ZIF-8 suspension and stirred at 700rpm for 10min at room temperature; after the reaction was completed, the solid was separated by centrifugation at 9000r / min for 20min, washed with deionized water, and dried to constant weight to obtain t-ZIF-8; (2) 8g of fusible polyacrylonitrile copolymer, 1.6g of t-ZIF-8 and 40g of composite diluent (35g of caprolactam and 5g of triacetylglycerol) were stirred continuously at 400rpm and 150℃ for 1h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 200°C for 10 min. Then it was transferred to an air bath at 25°C for 6 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 24 h to remove the composite diluent. Then it was dried at 40°C for 4 h to obtain the t-ZIF-8 / PAN separation membrane with liquid-borne superhydrophobicity.

[0049] Testing showed that the membrane exhibited an underwater oil contact angle of 147.2° and an oil-to-water contact angle of 157.3°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 4286 L / m³. -2 h·bar, 96.8% and 7418 L / m -2 With a separation flux of 1052 L / m³ and a separation efficiency of over 95.2% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1052 L / m³. -2 h·bar, 96.4% and 1742 L / m -2 •h·bar, 95.0% and above.

[0050] Example 3: (1) 2g of ZIF-8 powder was sonicated with 100ml of deionized water at 240W and 40kHz for 60min at room temperature to obtain a uniformly dispersed ZIF-8 suspension; then 10g / L and 100ml of TA solution were added to the ZIF-8 suspension and stirred at 950rpm for 30min at room temperature; after the reaction was completed, the solid was separated by centrifugation at 10000r / min for 30min, washed with deionized water, and dried to constant weight to obtain t-ZIF-8; (2) 8g of fusible polyacrylonitrile copolymer, 0.8g of t-ZIF-8 and 40g of composite diluent (including 35g caprolactam and 5g triacetin) were stirred continuously at 800rpm and 200℃ for 4h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 200°C for 20 min. Then it was transferred to an air bath at 25°C for 6 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 48 h to remove the composite diluent. Then it was dried at 80°C for 8 h to obtain the t-ZIF-8 / PAN separation membrane with liquid-borne superhydrophobicity.

[0051] Testing showed that the membrane exhibited an underwater oil contact angle of 164.1° and an oil-to-water contact angle of 158.2°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for oil-in-water and water-in-oil emulsions without emulsifiers were 5871 L / m³. -2 h·bar, 96.4% and 6247 L / m -2 With a separation flux of 1387 L / m³ and a separation efficiency of over 94.5% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1387 L / m³. -2 h·bar, 95.9% and 1587 L / m -2 h bar, over 94.2%.

[0052] Example 4: (1) Preparation of UIO-66-(COOH)2; (2) 10g of fusible polyacrylonitrile copolymer, 1g of UIO-66-(COOH)2 and 40g of composite diluent (30g of diphenyl carbonate and 10g of polyvinyl alcohol) were stirred continuously at 400rpm and 150℃ for 1h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 150°C for 10 min. Then it was transferred to an air bath at 25°C for 7 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 24 h to remove the composite diluent. Then it was dried at 40°C for 4 h to obtain a UIO-66-(COOH)2 / PAN separation membrane with liquid-borne superhydrophobicity.

[0053] Testing showed that the membrane exhibits an underwater oil contact angle of 147.5° and an oil-water contact angle of 157.6°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 4286 L / m³. -2 h·bar, 96.8% and 7418 L / m -2 With a separation flux of 1052 L / m³ and a separation efficiency of over 95.2% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1052 L / m³. -2 h·bar, 96.4% and 1742 L / m -2 •h·bar, 95.0% and above.

[0054] Example 5: (1) Preparation of UIO-66-(COOH)2; (2) 10g of fusible polyacrylonitrile copolymer, 1.5g of UIO-66-(COOH)2 and 40g of composite diluent (including 35g of caprolactam and 5g of triacetylglycerol) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 minutes. Then it was transferred to an air bath at 25°C for 7 hours to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 36 hours to remove the composite diluent. Then it was dried at 60°C for 6 hours to obtain a UIO-66-(COOH)2 / PAN separation membrane with liquid-borne superhydrophobicity.

[0055] Testing showed that the membrane exhibited an underwater oil contact angle of 148.3° and an oil-water contact angle of 158.3°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for oil-in-water and water-in-oil emulsions without emulsifiers were 4392 L / m³. -2 h·bar, 96.4% and 7512 L / m -2 With a separation flux of 1168 L / m³ and a separation efficiency of over 95.7% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1168 L / m³. -2 h·bar, 96.5% and 1783 L / m -2 •h·bar, over 95.6%.

[0056] Example 6: (1) Preparation of UIO-66-(COOH)2; (2) 10g of fusible polyacrylonitrile copolymer, 2g of UIO-66-(COOH)2 and 40g of composite diluent (35g of ethylene carbonate and 5g of glycerol) were stirred continuously at 800rpm and 200℃ for 4h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 20 min. Then it was transferred to an air bath at 25°C for 6 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 48 h to remove the composite diluent. Then it was dried at 80°C for 8 h to obtain a UIO-66-(COOH)2 / PAN separation membrane with liquid-borne superhydrophobicity.

[0057] Testing showed that the membrane exhibited an underwater oil contact angle of 164.1° and an oil-to-water contact angle of 158.2°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5863 L / m³. -2 h·bar, 96.3% and 6251 L / m -2 With a separation flux of 1342 L / m³ and a separation efficiency of over 94.8% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1342 L / m³. -2 h·bar, 95.6% and 1493 L / m -2 ·h·bar, 94.4% or more.

[0058] Example 7: (1) MOF(UIO-66-NH2) and β-cyclodextrin in a mass ratio of 1:0.25 were added to deionized water. The ratio of the sum of the mass of MOF(UIO-66-NH2) and β-cyclodextrin to the volume of deionized water was 1 g: 200 mL. The mixture was sonicated at 120 W and 40 kHz for 30 min at room temperature to obtain a β-CD-MOF(UIO-66-NH2) suspension. The solid was separated by centrifugation at 8000 r / min for 10 min to obtain β-CD-MOF(UIO-66-NH2). (2) 15g of meltable polyacrylonitrile copolymer, 1.5g of β-CD-MOF (UIO-66-NH2) and 45g of composite diluent (including 30g of diphenyl carbonate and 10g of polyvinyl alcohol) were stirred continuously at 400rpm and 150℃ for 1h under nitrogen atmosphere to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 10 min. Then it was transferred to an air bath at 25°C for 7 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 24 h to remove the composite diluent. Then it was dried at 40°C for 4 h to obtain a β-CD-MOF / PAN separation membrane with liquid-borne superhydrophobicity.

[0059] Testing showed that the membrane exhibited an underwater oil contact angle of 142.9° and an oil-water contact angle of 138.9°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 4878 L / m³. -2 h·bar, 97.5% and 6410 L / m -2 With a separation flux of 1176 L / m³ and a separation efficiency of over 96.1% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1176 L / m³. -2 h·bar, 97.5% and 1743 L / m -2 ·h·bar, over 95.7%.

[0060] Example 8: (1) MOF(UIO-66-NH2) and β-cyclodextrin in a mass ratio of 1:1 were added to deionized water. The ratio of the sum of the mass of MOF(UIO-66-NH2) and β-cyclodextrin to the volume of deionized water was 1 g: 100 mL. The mixture was sonicated at 180 W and 40 kHz for 45 min at room temperature to obtain a β-CD-MOF(UIO-66-NH2) suspension. The solid was separated by centrifugation at 9000 r / min for 20 min to obtain β-CD-MOF(UIO-66-NH2). (2) 15g of meltable polyacrylonitrile copolymer, 2.25g of β-CD-MOF (UIO-66-NH2) and 45g of composite diluent (including 25g caprolactam and 20g triacetyl ester) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 minutes. Then it was transferred to an air bath at 25°C for 7 hours to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 36 hours to remove the composite diluent. Then it was dried at 60°C for 6 hours to obtain a β-CD-MOF / PAN separation membrane with liquid-borne superhydrophobicity.

[0061] Testing showed that the membrane exhibited an underwater oil contact angle of 167.4° and an oil-water contact angle of 162.7°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5457 L / m³. -2 h·bar, 96.9% and 7415 L / m -2 With a separation flux of 1354 L / m³ and a separation efficiency of over 97.2% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively above 97.2%. -2 h·bar, 95.9% and 1749 L / m -2 •h·bar, over 96.7%.

[0062] Comparative Example 6: (1) 15g of meltable polyacrylonitrile copolymer, 2.25g of MOF (UIO-66-NH2) and 45g of composite diluent (including 25g of caprolactam and 20g of triacetylglycerol) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection, but a uniform casting solution was not formed. (2) The uneven casting solution was poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 minutes and then transferred to an air bath at 25°C for 7 hours. Due to the unevenness of the casting solution, the prepared film could not be formed at all and could not be tested.

[0063] Example 9: (1) MOF(UIO-66-NH2) and β-cyclodextrin in a mass ratio of 2:1 were added to deionized water. The ratio of the sum of the mass of MOF(UIO-66-NH2) and β-cyclodextrin to the volume of deionized water was 1 g: 50 mL. The mixture was sonicated at 240 W and 40 kHz for 60 min at room temperature to obtain a β-CD-MOF(UIO-66-NH2) suspension. The solid was separated by centrifugation at 10000 r / min for 30 min to obtain β-CD-MOF(UIO-66-NH2). (2) 15g of fusible polyacrylonitrile copolymer, 3g of β-CD-MOF and 45g of composite diluent (35g of ethylene carbonate and 10g of glycerol) were stirred continuously at 800rpm and 200℃ for 4h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 200°C for 20 min. Then it was transferred to an air bath at 25°C for 7 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was immersed in deionized water for 48 h to remove the composite diluent. Then it was dried at 80°C for 8 h to obtain a β-CD-MOF / PAN separation membrane with liquid-borne superhydrophobicity.

[0064] Testing showed that the membrane exhibited an underwater oil contact angle of 158.6° and an oil-to-water contact angle of 155.4°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5283 L / m³. -2 h·bar, 97.2% and 6839 L / m -2 With a separation flux of 1268 L / m³ and a separation efficiency of over 96.5% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1268 L / m³. -2 h·bar, 96.3% and 1745 L / m -2 •h·bar, over 95.9%.

[0065] Example 10: (1) Preparation of Cu-MOF; (2) 10g of fusible polyacrylonitrile copolymer, 1g of Cu-MOF and 40g of composite diluent (30g of diphenyl carbonate and 10g of polyvinyl alcohol) were stirred continuously at 400rpm and 150℃ for 1h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 200°C for 20 min. Then it was transferred to an air bath at 25°C for 6 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 48 h to remove the composite diluent. Then it was dried at 80°C for 8 h to obtain a Cu-MOF / PAN separation membrane with liquid-borne superhydrophobicity.

[0066] Testing showed that the membrane exhibits an underwater oil contact angle of 150.4° and an oil-to-water contact angle of 147.8°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5875 L / m³. -2 h·bar, 97.2% and 6481 L / m -2 With a separation flux of 1387 L / m³ and a separation efficiency of over 96.4% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively above 96.4%. -2 h·bar, 96.4% and 2044 L / m -2 •h·bar, over 95.8%.

[0067] Example 11: (1) Preparation of Cu-MOF; (2) 10g of fusible polyacrylonitrile copolymer, 1.5g of Cu-MOF and 40g of composite diluent (35g of caprolactam and 5g of triacetylglycerol) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 minutes. Then it was transferred to an air bath at 25°C for 7 hours to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 36 hours to remove the composite diluent. Then it was dried at 60°C for 6 hours to obtain a Cu-MOF / PAN separation membrane with liquid-borne superhydrophobicity.

[0068] Testing showed that the membrane exhibited an underwater oil contact angle of 151.2° and an oil-to-water contact angle of 146.5°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5839 L / m³. -2 h·bar, 95.2% and 6391 L / m -2 With a separation flux of 1417 L / m³ and a separation efficiency of over 97.4% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1417 L / m³. -2 h·bar, 95.4% and 2033 L / m-2 ·h·bar, over 96.8%.

[0069] Example 12: (1) Preparation of Cu-MOF; (2) 10g of fusible polyacrylonitrile copolymer, 2g of Cu-MOF and 40g of composite diluent (35g of ethylene carbonate and 10g of glycerol) were stirred continuously at 800rpm and 200℃ for 4h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 200°C for 20 min. Then it was transferred to an air bath at 25°C for 8 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 48 h to remove the composite diluent. Then it was dried at 80°C for 8 h to obtain a Cu-MOF / PAN separation membrane with liquid-borne superhydrophobicity.

[0070] Testing showed that the membrane exhibits an underwater oil contact angle of 150.9° and an oil-water contact angle of 146.9°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5883 L / m³. -2 h·bar, 95.8% and 6471 L / m -2 With a separation flux of 1472 L / m³ and a separation efficiency of over 96.8% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1472 L / m³. -2 h·bar, 95.6% and 2083 L / m -2 ·h·bar, over 97.1%.

[0071] Example 13: (1) Add 1g of HAP and 4g of MOF-5 to 1000mL of DMF and sonicate at 120W and 40kHz for 30min at room temperature to achieve uniform dispersion; then stir at 70℃ and 600r / min for 12h, then centrifuge to collect the solid, wash with DMF and methanol alternately, and finally dry at 100℃ for 12h to obtain MOF-5@HAP; (2) 10g of fusible polyacrylonitrile copolymer, 2g of MOF-5@HAP and 40g of composite diluent (30g of diphenyl carbonate and 10g of polyvinyl alcohol) were stirred continuously at 400rpm and 150℃ for 1h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 150°C for 10 min. Then it was transferred to an air bath at 25°C for 7 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 24 h to remove the composite diluent. Then it was dried at 40°C for 4 h to obtain a MOF-5@HAP / PAN separation membrane with liquid-borne superhydrophobicity.

[0072] Testing showed that the membrane exhibited an underwater oil contact angle of 149.3° and an oil-to-water contact angle of 158.2°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5647 L / m³. -2 h·bar, 97.3% and 7418 L / m -2 With a separation flux of 1264 L / m³ and a separation efficiency of over 95.8% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively above 95.8%. -2 h·bar, 96.4 and 1769 L / m -2 ·h·bar, 95.7%.

[0073] Example 14: (1) Add 2g of HAP and 4g of MOF-5 to 900mL of DMF and sonicate at 180W and 40kHz for 45min at room temperature to achieve uniform dispersion; then stir at 75℃ and 700r / min for 18h, then centrifuge to collect the solid, wash with DMF and methanol alternately, and finally dry at 110℃ for 18h to obtain MOF-5@HAP; (2) 10g of meltable polyacrylonitrile copolymer, 1.5g of MOF-5@HAP and 40g of composite diluent (35g of caprolactam and 5g of triacetin) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 min. Then it was transferred to an air bath at 25°C for 6 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 36 h to remove the composite diluent. Then it was dried at 60°C for 6 h to obtain the MOF-5@HAP / PAN separation membrane with liquid-borne superhydrophobicity.

[0074] Testing showed that the membrane exhibited an underwater oil contact angle of 151.6° and an oil-to-water contact angle of 157.3°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5532 L / m³. -2h·bar, 96.5% and 8265 L / m -2 With a separation flux of 1358 L / m³ and a separation efficiency of over 96.4% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively above 96.4%. -2 h·bar, 95.8% and 1493 -2 ·h·bar, 94.4% or more.

[0075] Comparative Example 7: (1) 10g of meltable polyacrylonitrile copolymer, 1.5g of MOF-5 and 40g of composite diluent (35g of caprolactam and 5g of triacetin) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection, but a uniform casting solution was not formed. (2) The uneven casting solution was poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 minutes and then transferred to an air bath at 25°C for 7 hours. Due to the unevenness of the casting solution, the prepared film could not be formed at all and could not be tested.

[0076] Example 15: (1) Add 4g of HAP and 4g of MOF-5 to 800mL of DMF and sonicate at 240W and 40kHz for 60min at room temperature to achieve uniform dispersion; then stir at 80℃ and 800r / min for 24h, then centrifuge to collect the solid, wash with DMF and methanol alternately, and finally dry at 120℃ for 24h to obtain MOF-5@HAP; (2) 10g of fusible polyacrylonitrile copolymer, 3g of MOF-5@HAP and 40g of composite diluent (35g of ethylene carbonate and 10g of glycerol) were stirred continuously at 800rpm and 200℃ for 4h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 200°C for 20 min. Then it was transferred to an air bath at 25°C for 8 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 48 h to remove the composite diluent. Then it was dried at 80°C for 8 h to obtain the MOF-5@HAP / PAN separation membrane with liquid-borne superhydrophobicity.

[0077] Testing showed that the membrane exhibits an underwater oil contact angle of 150.8° and an oil-water contact angle of 157.8°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5792 L / m³. -2 h·bar, 96.9% and 7367 L / m-2 With a separation flux of 1173 L / m³ and a separation efficiency of over 96.1% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively above 96.1%. -2 h·bar, 97.3% and 1743 L / m -2 ·h·bar, over 95.7%.

[0078] Example 16: (1) 0.1 g of CNT-COOH was added to a mixed solvent of 200 mL of ethanol and DMF (volume ratio 2:1) and sonicated at 120 W and 40 kHz for 10 min at room temperature to obtain a CNT-COOH suspension; 0.5 g of MIL-101(Fe) powder was added to a mixed solvent of 100 mL of ethanol and DMF (volume ratio 2:1) and sonicated at 120 W and 40 kHz for 10 min at room temperature to obtain a MIL-101(Fe) suspension; then the MIL-101(Fe) suspension was added dropwise to the CNT-COOH suspension and stirred at room temperature until homogeneous to obtain a mixture; then the mixture was centrifuged at 2000 rpm for 5 min, the precipitate was collected and washed with ethanol, and dried at 80 °C for 4 h to obtain MIL-101(Fe)@CNT; (2) 10g of fusible polyacrylonitrile copolymer, 1g of MIL-101(Fe)@CNT and 40g of composite diluent (including 35g caprolactam and 5g triacetyl ester) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 minutes. Then it was transferred to an air bath at 25°C for 7 hours to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was immersed in deionized water for 36 hours to remove the composite diluent. Then it was dried at 60°C for 6 hours to obtain the MIL-101@CNT / PAN separation membrane with liquid-borne superhydrophobicity.

[0079] Testing showed that the membrane exhibits an underwater oil contact angle of 159.3° and an oil-water contact angle of 151.4°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for oil-in-water and water-in-oil emulsions without emulsifiers were 5173 L / m³. -2 h·bar, 97.1% and 6397 L / m -2 With a separation flux of 1254 L / m³ and a separation efficiency of over 96.4% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1254 L / m³. -2 h·bar, 96.5% and 1843 L / m -2•h·bar, over 95.8%.

[0080] Example 17: (1) 0.1 g of CNT-COOH was added to a mixed solvent of 150 mL of ethanol and DMF (volume ratio 1:1) and sonicated at 180 W and 40 kHz for 20 min at room temperature to obtain a CNT-COOH suspension; 1 g of MIL-101(Fe) powder was added to a mixed solvent of 150 mL of ethanol and DMF (volume ratio 1:1) and sonicated at 180 W and 40 kHz for 20 min at room temperature to obtain a MIL-101(Fe) suspension; then the MIL-101(Fe) suspension was added dropwise to the CNT-COOH suspension and stirred at room temperature until homogeneous to obtain a mixture; then the mixture was centrifuged at 3000 rpm for 8 min, the precipitate was collected and washed with DMF, and dried at 90 °C for 5 h to obtain MIL-101(Fe)@CNT; (2) 10g of meltable polyacrylonitrile copolymer, 1.5g of MIL-101(Fe)@CNT and 40g of composite diluent (including 35g caprolactam and 5g triacetyl ester) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 minutes. Then it was transferred to an air bath at 25°C for 6 hours to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was immersed in deionized water for 36 hours to remove the composite diluent. Then it was dried at 60°C for 6 hours to obtain the MIL-101@CNT / PAN separation membrane with liquid-borne superhydrophobicity.

[0081] Testing showed that the membrane exhibited an underwater oil contact angle of 163.5° and an oil-to-water contact angle of 159.3°, thus demonstrating underwater superhydrophobicity. The separation flux and efficiency for emulsions without emulsifiers (both oil-in-water and water-in-oil types) were 5417 L / m³. -2 h·bar, 97.5% and 6918 L / m -2 With a separation flux of 1431 L / m³ and a separation efficiency of over 97.4% for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively 1431 L / m³. -2 h·bar, 97.1% and 1853 L / m -2 ·h·bar, over 96.8%.

[0082] Comparative Example 8: (1) 10g of fusible polyacrylonitrile copolymer, 1.5g of MIL-101(Fe) and 40g of composite diluent (including 35g of caprolactam and 5g of triacetin) were stirred continuously at 500rpm and 180℃ for 2h under nitrogen atmosphere protection, but a uniform casting solution was not formed. (2) The uneven casting solution was poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 180°C for 15 minutes and then transferred to an air bath at 25°C for 6 hours. Due to the unevenness of the casting solution, the prepared film could not be formed at all and the subsequent tests could not be completed.

[0083] Example 18: (1) 0.1 g of CNT-COOH was added to 100 mL of a mixed solvent of ethanol and DMF (volume ratio 1:1) and sonicated at 240 W and 40 kHz for 30 min at room temperature to obtain a CNT-COOH suspension; 2 g of MIL-101(Fe) powder was added to 200 mL of a mixed solvent of ethanol and DMF (volume ratio 1:1) and sonicated at 240 W and 40 kHz for 30 min at room temperature to obtain a MIL-101(Fe) suspension; then the MIL-101(Fe) suspension was added dropwise to the CNT-COOH suspension and stirred at room temperature until homogeneous to obtain a mixture; then the mixture was centrifuged at 4000 rpm for 10 min, the precipitate was collected and washed with DMF, and dried at 100 °C for 6 h to obtain MIL-101(Fe)@CNT; (2) 10g of fusible polyacrylonitrile copolymer, 3g of MIL-101(Fe)@CNT and 40g of composite diluent (35g of ethylene carbonate and 10g of glycerol) were stirred continuously at 800rpm and 200℃ for 4h under nitrogen atmosphere to obtain a homogeneous casting solution. (3) The casting solution was quickly poured into a double-layer glass mold and the glass was clamped with clamps. Then the mold was transferred to an oven at 200°C for 20 min. Then it was transferred to an air bath at 25°C for 8 h to allow the casting solution to undergo phase separation and solidification. After complete solidification, the mold was removed and the membrane was soaked in deionized water for 48 h to remove the composite diluent. Then it was dried at 80°C for 8 h to obtain the MIL-101@CNT / PAN separation membrane with liquid-borne superhydrophobicity.

[0084] Testing showed that the membrane's underwater oil contact angle was 160.2° and its oil-water contact angle was 156.3°, thus exhibiting underwater superhydrophobicity. The separation flux and efficiency for emulsions in both oil-in-water and water-in-oil types without emulsifiers were 5168 L / m³. -2 h·bar, 96.9% and 6517 L / m -2With a separation flux of over 96.8% and a separation efficiency of 1356 L / m³ for oil-in-water and water-in-oil emulsions containing emulsifiers, the separation throughput and separation efficiency are respectively ·h·bar. -2 h·bar, 96.8% and 1724 L / m -2 ·h·bar, over 96.4%.

[0085] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A method for preparing a MOFs / PAN separation membrane with underwater superhydrophobicity, characterized in that, The method includes the following steps: Step 1: Preparation of MOFs; The MOFs are one of t-ZIF-8, UIO-66-(COOH)2, β-CD-MOF(UIO-66-NH2), Cu-MOF, MOF-5@HAP or MIL-101(Fe)@CNT; Step 2, Preparation of casting solution: Melt the fusible polyacrylonitrile copolymer, composite diluent and MOFs obtained in step 1 to form a homogeneous casting solution; The composite diluent consists of a primary diluent and a secondary diluent; the primary diluent is one of caprolactam, ethylene carbonate, or diphenyl carbonate; the secondary diluent is one of polyvinyl alcohol, glycerol, or triacetin. The meltable polyacrylonitrile-based copolymer is obtained by mixing acrylonitrile, a second monomer and an unsaturated ultraviolet light-sensitive crosslinking agent, adding an initiator, and reacting to obtain the meltable polyacrylonitrile-based copolymer. The second monomer includes at least one of methyl acrylate, methyl methacrylate, itaconic acid, and vinylimidazole; Unsaturated UV-sensitive crosslinking agents include at least one of 4-acryloyloxybenzophenone, 2-hydroxy-4-acryloyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 4-methacryloyloxybenzophenone, and stearyl benzophenone; Step 3: Preparation of MOFs / PAN separation membrane with underwater superhydrophobicity: MOFs / PAN separation membrane with underwater superhydrophobicity is prepared by thermally induced phase separation using the casting solution obtained in Step 2.

2. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 1, characterized in that, In step 1, the preparation method of t-ZIF-8 is as follows: ZIF-8 particles are uniformly dispersed in deionized water to obtain ZIF-8 suspension; then TA solution is added to ZIF-8 suspension for reaction. After the reaction is completed, the solid is separated by centrifugation, washed, and dried to constant weight to obtain t-ZIF-8. The process for uniform dispersion is as follows: ultrasonication is used at room temperature, with an ultrasonic power of 120~240W, an ultrasonic frequency of 40kHz, and an ultrasonic time of 0.5~1h. The concentration of the TA solution is 3~20 g / L, the mass ratio of ZIF-8 particles to deionized water is 1:50~200, and the volume ratio of ZIF-8 suspension to TA solution is 1:0.5~2. The reaction process is as follows: stirring is used at a speed of 700-950 rpm, the reaction time is 10-30 min, and the temperature is room temperature; The centrifugation process is as follows: rotation speed 8000~10000 r / min, time 10~30 min; Deionized water is used for washing.

3. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 1, characterized in that, In step 1, the preparation method of β-CD-MOF(UIO-66-NH2) is as follows: MOF(UIO-66-NH2) and β-cyclodextrin are uniformly dispersed in deionized water to obtain β-CD-MOF(UIO-66-NH2) suspension, and the solid is separated by centrifugation to obtain β-CD-MOF(UIO-66-NH2); The mass ratio of MOF(UIO-66-NH2) to β-cyclodextrin is 1~2:0.25~1, and the ratio of the sum of the masses of MOF(UIO-66-NH2) and β-cyclodextrin to the volume of deionized water is 1g:50~200ml. The process for uniform dispersion is as follows: ultrasonic method is used, with ultrasonic power of 120~240W, ultrasonic frequency of 40kHz, and ultrasonic time of 0.5~1h. The centrifugation process is: 8000~10000r / min, centrifugation time is 10~30min.

4. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 1, characterized in that, In step 1, the preparation method of MOF-5@HAP is as follows: pre-dried HAP and MOF-5 are uniformly dispersed in DMF, and then stirred to achieve uniform loading of MOF-5 on the surface of HAP. The solid is collected by centrifugation. The solid is then washed with DMF and then washed with methanol for solvent exchange. After activation and constant weight, MOF-5@HAP is obtained. The process for uniform dispersion is as follows: ultrasonic method is used, with ultrasonic power of 120~240W, ultrasonic frequency of 40kHz, ultrasonic time of 0.5~1h, and temperature of 70~80℃. The mass ratio of MOF-5 to HAP is 1~4:1; the ratio of the sum of the masses of MOF-5 and HAP to the volume of DMF is 1g:50~200ml; The stirring process is as follows: temperature 70~80℃, rotation speed 600~800r / min, time 12~24h; The activation process is as follows: temperature 100~120℃, time 12~24h.

5. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 1, characterized in that, In step 1, the preparation method of MIL-101(Fe)@CNT is as follows: CNT-COOH is uniformly dispersed in a mixed solvent of ethanol and DMF to obtain a CNT-COOH suspension; dried MIL-101(Fe) powder is uniformly dispersed in a mixed solvent of ethanol and DMF to obtain a MIL-101(Fe) suspension; then the MIL-101(Fe) suspension is added dropwise to the CNT-COOH suspension and stirred at room temperature until homogeneous to obtain a mixture; then the mixture is centrifuged at low speed, the precipitate is collected and washed with ethanol or DMF, and dried to obtain MIL-101(Fe)@CNT; The process for uniform dispersion is as follows: ultrasonic method is used, with ultrasonic power of 120~240W, ultrasonic frequency of 40kHz, and ultrasonic time of 10~30min. The mass ratio of MIL-101(Fe) to CNT-COOH is 5~20:1; the solid-liquid ratio of the CNT-COOH suspension is 0.1g:50~200ml; the solid-liquid ratio of the MIL-101(Fe) suspension is 1g:50~200ml; the volume ratio of ethanol to DMF is 1~2:1~2. The process for low-speed centrifugation is as follows: the rotation speed is 2000~4000 rpm, and the time is 5~10 min; The drying process is as follows: temperature 80~100℃, time 4~6h.

6. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 1, characterized in that, In step 2, the mass of the primary diluent accounts for 50-100% of the mass of the composite diluent.

7. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 1, characterized in that, In step 2, the mass of the meltable polyacrylonitrile-based copolymer is 15-35% of the mass of the composite diluent; the mass of the MOFs is 10-30% of the mass of the meltable polyacrylonitrile-based copolymer.

8. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 1, characterized in that, In step 2, the melting process is as follows: stirring is used until all components are completely melted in an oxygen-free environment, the stirring speed is 400~800 rpm, the stirring time is 1~4 h, and the stirring temperature is 150~200℃.

9. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 8, characterized in that, In step 2, the oxygen-free environment is either an inert gas environment or a nitrogen environment, and the inert gas used is argon or helium.

10. The method for preparing the MOFs / PAN separation membrane with underwater superhydrophobicity according to claim 1, characterized in that, In step 3, the thermally induced phase separation method specifically involves: transferring the casting solution to an environment of 150~200℃ and holding it at that temperature for 10~20 minutes to allow the casting solution to flow; then transferring it to an air bath at 25~30℃ for 6~8 hours to allow the casting solution to undergo phase separation and solidification; after complete solidification, immersing it in deionized water for 24~48 hours to remove the composite diluent, and then drying it at 40~80℃ for 4~8 hours to constant weight to obtain a MOFs / PAN separation membrane with underwater superhydrophobicity.

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