A super-hydrophobic covalent organic framework / metal mesh composite film and a preparation method and application thereof

Abstract

The application provides a preparation method of a super-hydrophobic covalent organic framework / metal mesh composite film, and belongs to the technical field of covalent organic framework structure materials, and comprises the following steps: sequentially reacting a copper mesh in 3-aminopropyl triethoxysilane toluene solution and triformylphloroglucinol suspension to obtain an aldehyde group modified copper mesh; immersing the aldehyde group modified copper mesh in a COF mother liquor to obtain an intermediate copper mesh; and sequentially modifying the intermediate copper mesh in polyvinyl alcohol aqueous solution and octadecyltrichlorosilane n-hexane solution to obtain the super-hydrophobic covalent organic framework / metal mesh composite film. The super-hydrophobic covalent organic framework / metal mesh composite film prepared by the application can reach an oil flux of 30-40 L / (m 2 ·s) at room temperature, and the separation property remains almost unchanged after 10 cycles of oil-water separation, and has a good application prospect in the fields of environmental protection and water treatment.

Description

Technical Field

[0001] This invention relates to the field of covalent organic framework structure materials technology, and in particular to a superhydrophobic covalent organic framework / metal mesh composite film, its preparation method and application. Background Technology

[0002] Gravity separation, flotation, and electrocoagulation are traditional methods for treating oily wastewater, but they suffer from high energy consumption and low efficiency. Membrane separation technology, compared to other methods, is one of the means to achieve efficient separation of oily wastewater. Due to its low operating cost, ease of operation, energy saving, and environmental friendliness, it is widely used in modern chemical separation processes. Based on the widespread application of membrane separation technology in oil-water separation, a series of membrane materials with superhydrophobic and oleophilic properties have been developed. These membrane materials allow oil to pass through smoothly while effectively blocking water, thus achieving efficient separation of oily wastewater. However, these new oil-water separation membrane materials also have certain shortcomings, such as poor chemical stability, poor thermal stability, poor mechanical stability, and low separation efficiency. Therefore, developing a highly stable and efficient oil-water separation membrane material remains a challenge. Summary of the Invention

[0003] The purpose of this invention is to provide a superhydrophobic covalent organic framework / metal mesh composite membrane, its preparation method, and its application.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preparing a superhydrophobic covalent organic framework / metal mesh composite film, comprising the following steps:

[0006] (1) The copper mesh was reacted sequentially in a 3-aminopropyltriethoxysilane toluene solution and a trialdehyde phloroglucinol suspension to obtain an aldehyde-modified copper mesh;

[0007] (2) The aldehyde-modified copper mesh was immersed in the COF mother liquor to react and obtain the intermediate copper mesh;

[0008] (3) The intermediate copper mesh is modified sequentially in an aqueous solution of polyvinyl alcohol and an octadecyltrichlorosilane solution in hexane to obtain the superhydrophobic covalent organic framework / metal mesh composite film.

[0009] Preferably, the mass concentration of the 3-aminopropyltriethoxysilane toluene solution in step (1) is 3-5%;

[0010] The reaction temperature in 3-aminopropyltriethoxysilane toluene solution is 100–120 °C, and the reaction time is 1–3 h.

[0011] Preferably, the concentration of the trialdehyde phloroglucinol suspension in step (1) is 1.5–3 mg / mL;

[0012] The trialdehyde phloroglucinol suspension contains trialdehyde phloroglucinol and 1,4-dioxane;

[0013] The reaction temperature in the trialdehyde phloroglucinol suspension is 70–90 °C, and the reaction time is 1–3 h.

[0014] Preferably, the reaction in step (2) is repeated ≥ 2 times, the reaction temperature is 110~130℃, and the single reaction time is 2~4 days.

[0015] Preferably, the COF mother liquor in step (2) comprises a trialdehyde phloroglucinol suspension, a p-phenylenediamine solution, and acetic acid;

[0016] The volume ratio of the trialdehyde phloroglucinol suspension, the p-phenylenediamine solution, and the acetic acid is 10–20:10–20:1–2.

[0017] Preferably, the concentration of the trialdehyde resorcinol suspension is 1.5–3 mg / mL, and the trialdehyde resorcinol suspension contains trialdehyde resorcinol and mesitylene.

[0018] The concentration of the p-phenylenediamine solution is 3-6 mg / mL, and the solvent of the p-phenylenediamine solution is N,N-dimethylformamide.

[0019] Preferably, the mass concentration of the polyvinyl alcohol aqueous solution in step (3) is 0.1-0.5%;

[0020] The modification temperature in the polyvinyl alcohol aqueous solution is 15–30℃, and the modification time is 20–40 min.

[0021] Preferably, the concentration of the hexane solution of octadecyltrichlorosilane in step (3) is 0.1-0.5%;

[0022] The reaction in a hexane solution of octadecyltrichlorosilane is carried out at a temperature of 15–30 °C for a time of 1–4 h.

[0023] The present invention also provides a superhydrophobic covalent organic framework / metal mesh composite membrane obtained by the preparation method described above.

[0024] The present invention also provides the application of the superhydrophobic covalent organic framework / metal mesh composite membrane in oil-water separation.

[0025] The method for preparing a superhydrophobic covalent organic framework / metal mesh composite membrane provided by this invention comprises the following steps: reacting a copper mesh sequentially in a 3-aminopropyltriethoxysilane-toluene solution and a trialdehyde-resorcinol suspension to obtain an aldehyde-modified copper mesh; immersing the aldehyde-modified copper mesh in a COF mother liquor to obtain an intermediate copper mesh; and modifying the intermediate copper mesh sequentially in a polyvinyl alcohol aqueous solution and an octadecyltrichlorosilane-hexane solution to obtain the superhydrophobic covalent organic framework / metal mesh composite membrane. The superhydrophobic covalent organic framework / metal mesh composite membrane prepared by this invention can separate immiscible liquid organic matter and water by gravity filtration at room temperature, with an oil flux reaching 30–40 L / (m³). 2 The oil-water separation performance remained almost unchanged during 10 oil-water separation cycles, showing promising application prospects in environmental protection and water treatment. Attached Figure Description

[0026] Figure 1 The XRD pattern of COF TpPa-1 in Example 1;

[0027] Figure 2 This is a SEM image of the superhydrophobic covalent organic framework / metal mesh composite membrane of Example 1;

[0028] Figure 3 The contact angle diagram of the superhydrophobic covalent organic framework / metal mesh composite membrane in Example 1 with water is shown.

[0029] Figure 4 The diagram shows the separation efficiency and separation flux of the superhydrophobic covalent organic framework / metal mesh composite membranes in Examples 1-4.

[0030] Figure 5 This is a cyclic diagram of the oil-water separation test of the superhydrophobic covalent organic framework / metal mesh composite membrane in Example 1. Detailed Implementation

[0031] This invention provides a method for preparing a superhydrophobic covalent organic framework / metal mesh composite film, comprising the following steps:

[0032] (1) The copper mesh was reacted sequentially in a 3-aminopropyltriethoxysilane toluene solution and a trialdehyde phloroglucinol suspension to obtain an aldehyde-modified copper mesh;

[0033] (2) The aldehyde-modified copper mesh was immersed in the COF mother liquor to react and obtain the intermediate copper mesh;

[0034] (3) The intermediate copper mesh is modified sequentially in an aqueous solution of polyvinyl alcohol and an octadecyltrichlorosilane solution in hexane to obtain the superhydrophobic covalent organic framework / metal mesh composite film.

[0035] In this invention, the copper mesh is preferably a red copper mesh, and the mesh count of the red copper mesh is preferably 180-220 mesh, more preferably 190-210 mesh, and even more preferably 195-205 mesh.

[0036] In this invention, the copper mesh needs to undergo pretreatment before the reaction. The pretreatment is as follows: the copper mesh is first immersed in hydrochloric acid, acetone and distilled water in sequence, and then ultrasonicated and dried to complete the pretreatment.

[0037] In this invention, the concentration of the hydrochloric acid is preferably 0.5-2M, more preferably 0.8-1.7M, and even more preferably 1.0-1.5M; the ultrasonic time is preferably 5-15 min, more preferably 8-10 min; and the drying temperature is preferably 15-30℃, more preferably 18-27℃, and even more preferably 20-25℃.

[0038] In this invention, the 3-aminopropyltriethoxysilane is dissolved in toluene to obtain the 3-aminopropyltriethoxysilane toluene solution.

[0039] In this invention, the mass concentration of the 3-aminopropyltriethoxysilane toluene solution in step (1) is preferably 3-5%, more preferably 3.5-4.5%, and even more preferably 3.8-4.2%.

[0040] In this invention, the principle of the reaction in step (1) is as follows: the copper mesh is functionalized in a 3-aminopropyltriethoxysilane toluene solution to obtain an amino-functionalized copper mesh; then it is functionalized in a trialdehyde phloroglucinol suspension to obtain an aldehyde-functionalized copper mesh.

[0041] In this invention, the reaction temperature in the 3-aminopropyltriethoxysilane toluene solution is preferably 100-120°C, more preferably 105-115°C, and even more preferably 108-112°C; the reaction time is preferably 1-3 h, more preferably 1.5-2.5 h, and even more preferably 1.8-2.2 h.

[0042] After the reaction in a toluene solution of 3-aminopropyltriethoxysilane was completed, the mixture was washed with ethanol.

[0043] In this invention, an amino-functionalized copper mesh is obtained by reacting a copper mesh in a 3-aminopropyltriethoxysilane toluene solution, and then the amino-functionalized copper mesh is reacted in a trialdehyde phloroglucinol suspension.

[0044] In this invention, the concentration of the trialdehyde phloroglucinol suspension in step (1) is preferably 1.5 to 3 mg / mL, more preferably 1.8 to 2.7 mg / mL, and even more preferably 2.0 to 2.5 mg / mL.

[0045] In this invention, the trialdehyde phloroglucinol suspension comprises trialdehyde phloroglucinol and 1,4-dioxane.

[0046] In this invention, the trialdehyde-based resorcinol suspension is obtained by dispersing trialdehyde-based resorcinol in 1,4-dioxane.

[0047] In this invention, the reaction temperature in the trialdehyde-based phloroglucinol suspension is preferably 70-90°C, more preferably 75-85°C, and even more preferably 78-82°C. The reaction time is preferably 1-3 h, more preferably 1.5-2.5 h, and even more preferably 1.8-2.2 h.

[0048] In this invention, the number of reactions in step (2) is preferably ≥2 times, the temperature of the reaction is preferably 110~130℃, more preferably 115~125℃, more preferably 118~122℃, and the single reaction time is preferably 1~5d, more preferably 2~4d, more preferably 2.5~3.5d.

[0049] In this invention, a new COF mother liquor needs to be prepared for each reaction. After a single reaction, the copper mesh is washed and dried sequentially with anhydrous ethanol and anhydrous acetone. After a final wash and dry, the intermediate copper mesh is obtained.

[0050] In this invention, the intermediate copper mesh is a COF TpPa-1 film.

[0051] In this invention, the principle of generating the COF TpPa-1 membrane in step (2) is as follows:

[0052]

[0053] In this invention, the COF mother liquor in step (2) comprises a trialdehyde phloroglucinol suspension, a p-phenylenediamine solution, and acetic acid.

[0054] In this invention, the trialdehyde phloroglucinol suspension is first mixed with the p-phenylenediamine solution and then acetic acid is added dropwise.

[0055] In this invention, the volume ratio of the trialdehyde phloroglucinol suspension, the p-phenylenediamine solution, and the acetic acid is preferably 10-20:10-20:1-2, more preferably 12-18:12-18:1.2-1.8, and even more preferably 14-16:14-16:1.4-1.6.

[0056] In this invention, the concentration of the trialdehyde-based phloroglucinol suspension is preferably 1.5–3 mg / mL, more preferably 1.8–2.7 mg / mL, and even more preferably 2.0–2.5 mg / mL. The trialdehyde-based phloroglucinol suspension contains trialdehyde-based phloroglucinol and mesitylene.

[0057] In this invention, the trialdehyde-resorcinol suspension is obtained by dispersing trialdehyde in mesitylene.

[0058] In this invention, the concentration of the p-phenylenediamine solution is preferably 3-6 mg / mL, more preferably 4-5 mg / mL, and even more preferably 4.2-4.8 mg / mL, and the solvent of the p-phenylenediamine solution is N,N-dimethylformamide.

[0059] In this invention, the p-phenylenediamine solution is obtained by dissolving p-phenylenediamine in N,N-dimethylformamide.

[0060] In this invention, polyvinyl alcohol is dissolved in water to obtain the polyvinyl alcohol aqueous solution.

[0061] In this invention, the melting temperature is preferably 80-95°C, more preferably 85-90°C, and even more preferably 87-88°C.

[0062] In this invention, the mass concentration of the polyvinyl alcohol aqueous solution in step (3) is preferably 0.1-0.5%, more preferably 0.15-0.45%, and even more preferably 0.20-0.40%.

[0063] In this invention, the preferred temperature for modification in an aqueous polyvinyl alcohol solution is 15–30°C, more preferably 20–25°C, and even more preferably 22–23°C. The preferred modification time is 20–40 min, more preferably 25–35 min, and even more preferably 28–32 min.

[0064] In this invention, the intermediate copper mesh (COF TpPa-1 membrane) is removed after complete modification with polyvinyl alcohol aqueous solution, washed with deionized water and dried to obtain COF TpPa-1@PVA membrane.

[0065] In this invention, the drying temperature is preferably 50-70°C, more preferably 55-65°C, and even more preferably 58-62°C. The drying time is preferably 0.5-2 hours, more preferably 0.8-1.7 hours, and even more preferably 1.0-1.5 hours.

[0066] In this invention, octadecyltrichlorosilane is dissolved in n-hexane to obtain a n-hexane solution of octadecyltrichlorosilane.

[0067] In this invention, the mass concentration of the octadecyltrichlorosilane n-hexane solution in step (3) is preferably 0.1-0.5%, more preferably 0.15-0.45%, and even more preferably 0.20-0.40%.

[0068] In this invention, the reaction temperature in the hexane solution of octadecyltrichlorosilane is preferably 15-30°C, more preferably 20-25°C, and even more preferably 22-23°C. The reaction time is preferably 1-4 h, more preferably 1.5-3.5 h, and even more preferably 2.0-3.0 h.

[0069] In this invention, after the reaction of octadecyltrichlorosilane in n-hexane is completed, the solution is removed, washed with anhydrous ethanol, and dried to obtain a superhydrophobic covalent organic framework / metal mesh composite membrane, namely COF TpPa-1@PVA@OTS membrane.

[0070] In this invention, the drying temperature is preferably 15-30°C, more preferably 18-27°C, and even more preferably 20-25°C.

[0071] The present invention also provides a superhydrophobic covalent organic framework / metal mesh composite membrane obtained by the preparation method described above.

[0072] The present invention also provides the application of the superhydrophobic covalent organic framework / metal mesh composite membrane in oil-water separation.

[0073] In this invention, unless otherwise specified, all raw materials required for preparation are commercially available products well known to those skilled in the art.

[0074] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0075] Example 1

[0076] A 3×3cm, 200-mesh copper mesh was sequentially immersed in hydrochloric acid (1M), acetone, and distilled water. After removal, it was sonicated for 10 minutes and dried at 25°C to complete the copper mesh pretreatment.

[0077] 3-Aminopropyltriethoxysilane was dissolved in toluene to obtain a 3% (w / w) 3-aminopropyltriethoxysilane toluene solution.

[0078] The above-mentioned concentration of 3-aminopropyltriethoxysilane toluene solution was placed in a reaction vessel, and the pretreated copper mesh was placed in the reaction vessel. The reaction was carried out at 110°C for 2 hours. After the functionalization modification was completed, the copper mesh was removed and cleaned with ethanol to obtain an amino-functionalized copper mesh.

[0079] Trialdehyde phloroglucinol was dispersed in 1,4-dioxane to obtain a suspension of trialdehyde phloroglucinol with a concentration of 2.0 mg / mL;

[0080] Take the above-mentioned concentration of trialdehyde-modified phloroglucinol suspension, place the amino-functionalized copper mesh in the suspension, and react at 80°C for 2 hours to obtain the aldehyde-functionalized copper mesh.

[0081] Trialdehyde resorcinol was dispersed in mesitylene to obtain a suspension of trialdehyde resorcinol with a concentration of 2.0 mg / mL;

[0082] p-Phenylenediamine was dissolved in N,N-dimethylformamide to obtain a p-Phenylenediamine solution with a concentration of 4 mg / mL;

[0083] Mix 15 mL each of the above-mentioned concentration of trialdehyde phloroglucinol suspension and p-phenylenediamine solution, and then add 1.5 mL of glacial acetic acid to obtain COF mother liquor.

[0084] An aldehyde-functionalized copper mesh was immersed in a COF mother liquor and reacted at 120°C for 3 days. After removal, it was washed and dried with anhydrous ethanol and anhydrous acetone, respectively. Then, the COF mother liquor was prepared again according to the same ratio, and the copper mesh was immersed in the prepared COF mother liquor. The above steps of immersing in COF mother liquor were repeated to obtain the intermediate copper mesh, namely the COF TpPa-1 membrane.

[0085] Polyvinyl alcohol was placed in water and dissolved at 90°C to obtain a polyvinyl alcohol aqueous solution with a mass concentration of 0.1%.

[0086] Take the polyvinyl alcohol aqueous solution of the above concentration, immerse the COF TpPa-1 membrane in the solution and modify it at 25℃ for 30 min. Wash it several times with deionized water and dry it at 60℃ for 1 h to obtain the COF TpPa-1@PVA membrane.

[0087] Octadecyltrichlorosilane was dissolved in n-hexane to obtain a n-hexane solution with a mass concentration of 0.5% octadecyltrichlorosilane.

[0088] The COF TpPa-1@PVA membrane was immersed in a hexane solution of octadecyltrichlorosilane of the above concentration. After modification at 25°C for 2 hours, the membrane was removed, washed with anhydrous ethanol, and dried at 25°C to obtain a superhydrophobic covalent organic framework / metal mesh composite membrane, namely COF TpPa-1@PVA@OTS membrane.

[0089] The COFTpPa-1 prepared in this embodiment was subjected to XRD analysis, and the results are as follows: Figure 1 As shown, from Figure 1 A strong peak is observed at 4.7°. Small peaks also appear at 8.0° and 27°, indicating the successful formation of the COF TpPa-1 structure.

[0090] The superhydrophobic covalent organic framework / metal mesh composite film prepared in this embodiment was analyzed by SEM, and the results are as follows: Figure 2 As shown, from Figure 2 It can be seen that COF TpPa-1 is dispersed and covered on the copper grid.

[0091] The superhydrophobicity of the superhydrophobic covalent organic framework / metal mesh composite film prepared in this embodiment was tested using a contact angle tester, and the results are as follows: Figure 3 As shown, from Figure 3 As can be seen, the superhydrophobic covalent organic framework / metal mesh composite film obtained in this embodiment has a water contact angle of 150.2° in air.

[0092] The superhydrophobic covalent organic framework / metal mesh composite membrane prepared in this embodiment was tested for its oil-water separation performance. The method is as follows: The superhydrophobic covalent organic framework / metal mesh composite membrane prepared in this embodiment was installed between the clamps. A mixed solution containing 10 mL of dichloromethane and 10 mL of water was poured into the oil-water separation device, allowing it to retain water under the action of gravity. The timing was started, and stopped when no liquid permeated through the membrane layer.

[0093] The specific separation effect is as follows: Figure 4 As shown, from Figure 4 It can be seen that the separation flux for dichloromethane can reach 38 L / (m³). 2 ·s -1 ).

[0094] The separation performance test of the above oil-water mixture system was repeated 10 times. The specific results are as follows: Figure 5 As shown, from Figure 5 It can be seen that after 10 oil-water separations, the separation performance of the superhydrophobic covalent organic framework / metal mesh composite membrane remains basically unchanged.

[0095] Using formula The separation flux was calculated to be 38 L / (m²). 2 ·s -1 ).

[0096] The residual water content in the solution after membrane separation is determined using the formula... The separation efficiency was calculated to be above 99.9%.

[0097] Example 2

[0098] A 3×3cm, 200-mesh copper mesh was sequentially immersed in hydrochloric acid (1M), acetone, and distilled water. After removal, it was sonicated for 10 minutes and dried at 25°C to complete the copper mesh pretreatment.

[0099] 3-Aminopropyltriethoxysilane was dissolved in toluene to obtain a 4% (w / w) 3-aminopropyltriethoxysilane toluene solution.

[0100] Take the above-mentioned concentration of 3-aminopropyltriethoxysilane toluene solution and place it in a reaction vessel. Put the pretreated copper mesh into the reaction vessel and react at 100°C for 1 hour for functionalization modification. After taking it out, wash the copper mesh with ethanol to obtain amino-functionalized copper mesh.

[0101] Trialdehyde phloroglucinol was dispersed in 1,4-dioxane to obtain a suspension of trialdehyde phloroglucinol with a concentration of 1.5 mg / mL;

[0102] Take the above-mentioned concentration of trialdehyde-modified phloroglucinol suspension, place the amino-functionalized copper mesh in the suspension, and react at 70°C for 1 hour to obtain the aldehyde-functionalized copper mesh.

[0103] Trialdehyde resorcinol was dispersed in mesitylene to obtain a suspension of trialdehyde resorcinol with a concentration of 2.0 mg / mL;

[0104] p-Phenylenediamine was dissolved in N,N-dimethylformamide to obtain a p-Phenylenediamine solution with a concentration of 4 mg / mL;

[0105] Mix 15 mL each of the above-mentioned concentration of trialdehyde phloroglucinol suspension and p-phenylenediamine solution, and then add 1.5 mL of glacial acetic acid to obtain COF mother liquor.

[0106] An aldehyde-functionalized copper mesh was immersed in a COF mother liquor and reacted at 110°C for 1 day. After removal, it was washed with anhydrous ethanol and anhydrous acetone and dried. Then, the COF mother liquor was prepared again according to the same ratio, and the copper mesh was immersed in the prepared COF mother liquor. The above steps of immersing in COF mother liquor were repeated to obtain the intermediate copper mesh, i.e., the COF TpPa-1 membrane.

[0107] Polyvinyl alcohol was placed in water and dissolved at 90°C to obtain a polyvinyl alcohol aqueous solution with a mass concentration of 0.2%.

[0108] Take the polyvinyl alcohol aqueous solution of the above concentration, immerse the COF TpPa-1 membrane in the solution and modify it at 15℃ for 20 min. Wash it several times with deionized water and dry it at 60℃ for 1 h to obtain the COF TpPa-1@PVA membrane.

[0109] Octadecyltrichlorosilane was dissolved in n-hexane to obtain a n-hexane solution with a mass concentration of 0.1% octadecyltrichlorosilane.

[0110] The COF TpPa-1@PVA membrane was immersed in a hexane solution of octadecyltrichlorosilane of the above concentration. After modification at 15°C for 1 hour, the membrane was removed, washed with anhydrous ethanol, and dried at 25°C to obtain a superhydrophobic covalent organic framework / metal mesh composite membrane, namely COF TpPa-1@PVA@OTS membrane.

[0111] The superhydrophobic covalent organic framework / metal mesh composite membrane prepared in this embodiment was tested for its oil-water separation performance. The method is as follows: The superhydrophobic covalent organic framework / metal mesh composite membrane prepared in this embodiment was installed between the clamps. A mixed solution containing 10 mL of 1,2-dichloroethane and 10 mL of water was poured into the oil-water separation device, allowing it to retain water under the action of gravity. The timing was started, and the timing was stopped when no liquid permeated through the membrane layer.

[0112] The specific separation effect is as follows: Figure 4 As shown, from Figure 4 It can be seen that the separation flux for 1,2-dichloroethane can reach 34 L / (m³). 2 ·s -1 )

[0113] Using formula The separation flux was calculated to be 34 L / (m²). 2 ·s -1 ).

[0114] The residual water content in the solution after membrane separation is determined using the formula... The separation efficiency was calculated to be above 99.9%.

[0115] Example 3

[0116] A 3×3cm, 200-mesh copper mesh was sequentially immersed in hydrochloric acid (1M), acetone, and distilled water. After removal, it was sonicated for 10 minutes and dried at 25°C to complete the copper mesh pretreatment.

[0117] 3-Aminopropyltriethoxysilane was dissolved in toluene to obtain a 5% (w / w) 3-aminopropyltriethoxysilane toluene solution.

[0118] The above-mentioned concentration of 3-aminopropyltriethoxysilane toluene solution was placed in a reaction vessel, and the pretreated copper mesh was placed in the reaction vessel. The reaction was carried out at 120°C for 3 hours. After the functionalization modification was completed, the copper mesh was removed and cleaned with ethanol to obtain an amino-functionalized copper mesh.

[0119] Trialdehyde phloroglucinol was dispersed in 1,4-dioxane to obtain a trialdehyde phloroglucinol suspension with a concentration of 3 mg / mL;

[0120] Take the above-mentioned concentration of trialdehyde-modified phloroglucinol suspension, place the amino-functionalized copper mesh in the suspension, and react at 90°C for 3 hours to obtain the aldehyde-functionalized copper mesh.

[0121] Trialdehyde resorcinol was dispersed in mesitylene to obtain a suspension of trialdehyde resorcinol with a concentration of 1.5 mg / mL;

[0122] p-Phenylenediamine was dissolved in N,N-dimethylformamide to obtain a p-Phenylenediamine solution with a concentration of 6 mg / mL;

[0123] Take 10 mL each of the above-mentioned concentration of trialdehyde phloroglucinol suspension and p-phenylenediamine solution, mix them, and then add 1 mL of glacial acetic acid to obtain COF mother liquor.

[0124] An aldehyde-functionalized copper mesh was immersed in a COF mother liquor and reacted at 130°C for 5 days. After removal, it was washed with anhydrous ethanol and anhydrous acetone and dried. Then, the COF mother liquor was prepared again according to the same ratio, and the copper mesh was immersed in the prepared COF mother liquor again. The above steps of immersing in COF mother liquor were repeated to obtain the intermediate copper mesh, namely the COF TpPa-1 membrane.

[0125] Polyvinyl alcohol was placed in water and dissolved at 90°C to obtain a polyvinyl alcohol aqueous solution with a mass concentration of 0.5%.

[0126] Take a polyvinyl alcohol aqueous solution of the above concentration, immerse the COF TpPa-1 membrane in the solution and modify it at 25℃ for 25 min. Wash it several times with deionized water and dry it at 60℃ for 1 h to obtain the COF TpPa-1@PVA membrane.

[0127] Octadecyltrichlorosilane was dissolved in n-hexane to obtain a n-hexane solution of octadecyltrichlorosilane with a mass concentration of 0.3%.

[0128] The COF TpPa-1@PVA membrane was immersed in a hexane solution of octadecyltrichlorosilane of the above concentration. After modification at 30°C for 3 hours, the membrane was removed, washed with anhydrous ethanol, and dried at 25°C to obtain a superhydrophobic covalent organic framework / metal mesh composite membrane, namely COF TpPa-1@PVA@OTS membrane.

[0129] The superhydrophobic covalent organic framework / metal mesh composite membrane prepared in this embodiment was tested for its oil-water separation performance. The method is as follows: The superhydrophobic covalent organic framework / metal mesh composite membrane prepared in this embodiment was installed between the clamps. A mixed solution containing 10 mL of chloroform and 10 mL of water was poured into the oil-water separation device, allowing it to retain water under the action of gravity. The timing was started, and the timing was stopped when no liquid permeated through the membrane layer.

[0130] The specific separation effect is as follows: Figure 4 As shown, from Figure 4 It can be seen that the separation flux for chloroform can reach 35 L / (m²). 2 ·s -1 )

[0131] Using formula The separation flux was calculated to be 35 L / (m²). 2 ·s -1).

[0132] The residual water content in the solution after membrane separation is determined using the formula... The separation efficiency was calculated to be above 99.9%.

[0133] Example 4

[0134] A 3×3cm, 200-mesh copper mesh was sequentially immersed in hydrochloric acid (1M), acetone, and distilled water. After removal, it was sonicated for 10 minutes and dried at 25°C to complete the copper mesh pretreatment.

[0135] 3-Aminopropyltriethoxysilane was dissolved in toluene to obtain a 4.5% (w / w) 3-aminopropyltriethoxysilane toluene solution.

[0136] The above-mentioned concentration of 3-aminopropyltriethoxysilane toluene solution was placed in a reaction vessel, and the pretreated copper mesh was placed in the reaction vessel. The reaction was carried out at 115℃ for 1.5 h for functionalization modification. After removal, the copper mesh was cleaned with ethanol to obtain amino-functionalized copper mesh.

[0137] Trialdehyde phloroglucinol was dispersed in 1,4-dioxane to obtain a suspension of trialdehyde phloroglucinol with a concentration of 2.5 mg / mL;

[0138] Take the above-mentioned concentration of trialdehyde-modified phloroglucinol suspension, place the amino-functionalized copper mesh in the suspension, and react at 85°C for 1.5 h to obtain aldehyde-functionalized copper mesh.

[0139] Trialdehyde resorcinol was dispersed in mesitylene to obtain a suspension of trialdehyde resorcinol with a concentration of 2.0 mg / mL;

[0140] p-Phenylenediamine was dissolved in N,N-dimethylformamide to obtain a p-Phenylenediamine solution with a concentration of 4 mg / mL;

[0141] Mix 15 mL each of the above-mentioned concentration of trialdehyde phloroglucinol suspension and p-phenylenediamine solution, and then add 1.5 mL of glacial acetic acid to obtain COF mother liquor.

[0142] An aldehyde-functionalized copper mesh was immersed in a COF mother liquor and reacted at 115°C for 3 days. After removal, it was washed and dried with anhydrous ethanol and anhydrous acetone, respectively. Then, the COF mother liquor was prepared again according to the same ratio, and the copper mesh was immersed in the prepared COF mother liquor. The above steps of immersing in COF mother liquor were repeated to obtain the intermediate copper mesh, namely the COF TpPa-1 membrane.

[0143] Polyvinyl alcohol was placed in water and dissolved at 90°C to obtain a polyvinyl alcohol aqueous solution with a mass concentration of 0.45%.

[0144] Take the polyvinyl alcohol aqueous solution of the above concentration, immerse the COF TpPa-1 membrane in the solution and modify it at 15℃ for 20 min. Wash it several times with deionized water and dry it at 60℃ for 1 h to obtain the COF TpPa-1@PVA membrane.

[0145] Octadecyltrichlorosilane was dissolved in n-hexane to obtain a n-hexane solution of octadecyltrichlorosilane with a mass concentration of 0.45%.

[0146] The COF TpPa-1@PVA membrane was immersed in a hexane solution of octadecyltrichlorosilane of the above concentration. After modification at 22°C for 3.5 h, the membrane was removed, washed with anhydrous ethanol, and dried at 25°C to obtain a superhydrophobic covalent organic framework / metal mesh composite membrane, namely COF TpPa-1@PVA@OTS membrane.

[0147] The superhydrophobic covalent organic framework / metal mesh composite membrane prepared in this embodiment was tested for its oil-water separation performance. The method is as follows: The superhydrophobic covalent organic framework / metal mesh composite membrane prepared in this embodiment was installed between the clamps. A mixed solution containing 10 mL of carbon tetrachloride and 10 mL of water was poured into the oil-water separation device, allowing it to retain water under the action of gravity. The timing was started, and the timing was stopped when no liquid permeated through the membrane layer.

[0148] The specific separation effect is as follows: Figure 4 As shown, from Figure 4 It can be seen that the separation flux for carbon tetrachloride can reach 36 L / (m²). 2 ·s -1 )

[0149] Using formula The separation flux was calculated to be 36 L / (m²). 2 ·s -1 ).

[0150] The residual water content in the solution after membrane separation is determined using the formula... The separation efficiency was calculated to be above 99.9%.

[0151] As can be seen from the above embodiments, the present invention provides a method for preparing a superhydrophobic covalent organic framework / metal mesh composite membrane, comprising the following steps: reacting a copper mesh sequentially in a 3-aminopropyltriethoxysilane-toluene solution and a trialdehyde-resorcinol suspension to obtain an aldehyde-modified copper mesh; immersing the aldehyde-modified copper mesh in a COF mother liquor to obtain an intermediate copper mesh; and modifying the intermediate copper mesh sequentially in a polyvinyl alcohol aqueous solution and an octadecyltrichlorosilane-hexane solution to obtain the superhydrophobic covalent organic framework / metal mesh composite membrane. The superhydrophobic covalent organic framework / metal mesh composite membrane prepared by the present invention can separate immiscible liquid organic matter and water by gravity filtration at room temperature, with an oil flux reaching 30-40 L / (m³). 2 The oil-water separation performance remained almost unchanged during 10 oil-water separation cycles, showing promising application prospects in environmental protection and water treatment.

[0152] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a superhydrophobic covalent organic framework / metal mesh composite film, characterized in that, Includes the following steps: (1) The copper mesh was reacted sequentially in a 3-aminopropyltriethoxysilane toluene solution and a trialdehyde phloroglucinol suspension to obtain an aldehyde-modified copper mesh; (2) The aldehyde-modified copper mesh is immersed in the COF mother liquor to react and obtain the intermediate copper mesh; (3) The intermediate copper mesh is modified sequentially in a polyvinyl alcohol aqueous solution and an octadecyltrichlorosilane n-hexane solution to obtain the superhydrophobic covalent organic framework / metal mesh composite film. The COF mother liquor mentioned in step (2) contains a trialdehyde phloroglucinol suspension, a p-phenylenediamine solution, and acetic acid; The volume ratio of the trialdehyde phloroglucinol suspension, the p-phenylenediamine solution, and the acetic acid is 10~20:10~20:1~2; The mass concentration of the polyvinyl alcohol aqueous solution in step (3) is 0.1~0.5%; The modification temperature in the polyvinyl alcohol aqueous solution is 15~30℃, and the modification time is 20~40min; The mass concentration of the octadecyltrichlorosilane n-hexane solution in step (3) is 0.1~0.5%; The modification temperature of octadecyltrichlorosilane in n-hexane solution is 15~30℃, and the modification time is 1~4h.

2. The preparation method according to claim 1, characterized in that, The mass concentration of the 3-aminopropyltriethoxysilane toluene solution in step (1) is 3-5%; The reaction temperature in 3-aminopropyltriethoxysilane toluene solution is 100~120℃, and the reaction time is 1~3h.

3. The preparation method according to claim 1 or 2, characterized in that, The concentration of the trialdehyde phloroglucinol suspension mentioned in step (1) is 1.5~3 mg / mL; The trialdehyde phloroglucinol suspension contains trialdehyde phloroglucinol and 1,4-dioxane; The reaction temperature in the trialdehyde phloroglucinol suspension is 70~90℃, and the reaction time is 1~3h.

4. The preparation method according to claim 3, characterized in that, The reaction in step (2) is repeated ≥ 2 times, the reaction temperature is 110~130℃, and the single reaction time is 2~4 days.

5. The preparation method according to claim 4, characterized in that, The concentration of the trialdehyde-based phloroglucinol suspension is 1.5~3 mg / mL, and the trialdehyde-based phloroglucinol suspension contains trialdehyde-based phloroglucinol and mesitylene. The concentration of the p-phenylenediamine solution is 3~6 mg / mL, and the solvent of the p-phenylenediamine solution is N,N-dimethylformamide.

6. The superhydrophobic covalent organic framework / metal mesh composite membrane obtained by the preparation method according to any one of claims 1 to 5.

7. The application of the superhydrophobic covalent organic framework / metal mesh composite membrane according to claim 6 in oil-water separation.

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