A fluorine-functionalized composite ceramic membrane and its preparation method and application

Abstract

The present invention discloses a fluorine-functionalized composite ceramic membrane and its preparation method and application, belonging to the field of water treatment technology. The fluorine-functionalized composite ceramic membrane includes a ceramic membrane and a catalyst loaded on the surface of the ceramic membrane, wherein the catalyst is a fluorine-functionalized ZIF-67 complex. The present invention utilizes F…F fluorine affinity to form strong selective adsorption with PFASs molecules, while reconstructing the surface hydrogen bond network to reduce the energy barrier of water dissociation to generate active hydrogen, thereby achieving "adsorption-activation" synergistic enhancement. At the same time, the multi-level pore structure of the ceramic membrane improves mass transfer flux by forced convection, and the chemical bonding of fluorine-functionalized ZIF-67 to the ceramic substrate ensures interfacial electron transfer efficiency and long-term stability, breaking through the dual limitations of low mass transfer efficiency and high reaction energy barrier of trace PFASs, and providing a new approach for efficient defluorination of PFASs pollutants in complex water bodies.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and relates to a fluorine-functionalized composite ceramic membrane, a preparation method and an application thereof, and specifically relates to a fluorine-functionalized composite ceramic membrane, a preparation method thereof and an application thereof in removing perfluorinated compounds from water. Background Art

[0002] Perfluorinated compounds (PFASs) are a class of persistent pollutants with extremely high chemical stability and bioaccumulation, and are widely present in surface water, groundwater, and industrial wastewater. Their strong CF bonds make it difficult to effectively degrade them using traditional redox technologies, and the low concentration characteristics of trace PFASs further exacerbate the difficulty of removal. Electrochemical reduction defluorination technology has become a research hotspot due to its advantages such as being green, controllable, and requiring no chemical agents. However, it faces multiple challenges in practical applications: on the one hand, the diffusion and mass transfer efficiency of trace PFASs in water bodies is limited by low concentration gradients, and the low conductivity of water significantly inhibits the electron transfer rate; on the other hand, the anionic characteristics of PFASs easily form an electrostatic repulsion barrier on the cathode surface, which, combined with the competitive adsorption of coexisting anions, leads to severe obstruction of interfacial reaction kinetics.

[0003] Existing electrochemical cathode materials mostly rely on non-specific physical or chemical adsorption (such as activated carbon and metal oxides), and their adsorption capacity is easily affected by complex water environments. In addition, the catalytic active sites and adsorption functions of traditional electrodes lack a coordinated design, making it difficult to simultaneously achieve efficient enrichment of pollutants and directional activation of CF bonds. For example, the static adsorption mechanism cannot adapt to the dynamic mass transfer process, resulting in a sharp drop in defluorination efficiency under low concentration conditions; and the modification strategy of simply improving conductivity (such as carbon material loading) can accelerate electron transfer, but it cannot break through the key bottleneck of coupling selective adsorption and catalytic pathways.

[0004] Chinese patent publication number CN119746930A discloses a fluorinated ZIF-67 / graphene composite catalyst for treating coal chemical wastewater and its preparation method. The fluorinated ZIF-67 / graphene composite catalyst utilizes porous graphene as a carrier, loaded with fluorinated ZIF-67. This fluorinated ZIF-67 / graphene composite catalyst has a high ability to degrade organic pollutants and is suitable for treating difficult-to-biodegrade pollutants such as phenols and oils in coal chemical wastewater. However, the application of this fluorinated ZIF-67 / graphene composite catalyst for the removal of PFASs has not yet been demonstrated. Summary of the Invention

[0005] In response to the above problems, the present invention discloses a fluorine-functionalized composite ceramic membrane, a preparation method and application thereof. The fluorine-functionalized composite ceramic membrane of the present invention precisely anchors the fluorine-functional groups on the surface of the material, utilizes the F…F fluorinophilic effect to form a strong selective adsorption with PFASs molecules, and simultaneously reconstructs the surface hydrogen bond network to reduce the energy barrier of water dissociation to generate active hydrogen, thereby achieving "adsorption-activation" synergistic enhancement. The multi-level pore structure of the ceramic membrane improves the mass transfer flux through forced convection, and the chemical bonding between the fluorine-functionalized ZIF-67 and the ceramic substrate ensures the interfacial electron transfer efficiency and long-term stability. This technology breaks through the dual limitations of low mass transfer efficiency and high reaction energy barrier of trace PFASs, and provides a new way for the efficient defluorination of PFASs pollutants in complex water bodies.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a fluorine-functionalized composite ceramic membrane, comprising a ceramic membrane and a catalyst loaded on the surface of the ceramic membrane, wherein the catalyst is a fluorine-functionalized ZIF-67 complex.

[0008] In some embodiments, the catalyst loading is 0.2 mg / cm 2 -0.5 mg / cm 2 .

[0009] In some embodiments, the ceramic membrane is made of one of aluminum oxide, zirconium oxide, titanium oxide, or silicon oxide.

[0010] In some embodiments, the pore size of the ceramic membrane is 50 nm to 200 nm.

[0011] In some embodiments, the method for preparing the fluorine-functionalized ZIF-67 complex comprises the following steps:

[0012] S1. Dissolving cobalt nitrate hexahydrate in methanol to form solution A; dissolving 2-methylimidazole in methanol to form solution B; mixing the solution B with the solution A, stirring, aging, solid-liquid separation, washing, and drying to obtain a ZIF-67 precursor;

[0013] S2, adding ethanol and pentafluorobenzenethiophenol to the ZIF-67 precursor, dispersing, heating for reaction, washing and drying to obtain fluorine-functionalized ZIF-67;

[0014] S3. Mixing and dispersing the reduced graphene oxide with water to obtain a dispersion; adding the fluorine-functionalized ZIF-67 to the dispersion, performing secondary dispersion, solid-liquid separation, washing and drying to obtain a fluorine-functionalized ZIF-67 complex.

[0015] Preferably, the molar ratio of cobalt nitrate hexahydrate to 2-methylimidazole in step S1 is 1:5-10; more preferably 1:7-9; and even more preferably 1:8.

[0016] Preferably, the stirring time in step S1 is 0.5 h-2 h; more preferably 1 h-2 h; further preferably 1 h.

[0017] Preferably, the static aging time in step S1 is 20 hours to 30 hours; more preferably, it is 24 hours to 30 hours; and even more preferably, it is 24 hours.

[0018] Preferably, the washing in step S1 is washing with methanol 1-5 times.

[0019] Preferably, the molar ratio of pentafluorobenzenethiol to the ZIF-67 precursor in step S2 is 1:1-3.

[0020] Preferably, the heating reaction in step S2 is: reacting at 80°C-90°C for 10h-14h.

[0021] Preferably, the washing in step S2 is washing with ethanol and water in sequence for 1-5 times after the reaction is completed.

[0022] Preferably, the molar ratio of the reduced graphene oxide to the fluorine-functionalized ZIF-67 in step S3 is 1:4-6.

[0023] Preferably, the washing in step S3 is performed with water for 1-5 times.

[0024] The solid-liquid separation involved in the present invention is intended to achieve separation of the solid phase and the liquid phase, and is a conventional solid-liquid separation technique in the art. Therefore, its specific implementation is not limited, and precipitation, centrifugation, or filtration can be selected according to actual needs. For example, the solid-liquid separation in step S1 is centrifugation, and the solid-liquid separation in step S3 is vacuum filtration.

[0025] The purpose of the dispersion method involved in the present invention is to fully disperse the solid in the liquid phase to form a uniform dispersion. Therefore, the specific implementation method is not limited, and at least one of ultrasonic, stirring, and high-pressure homogenization methods can be selected according to actual needs. The dispersion described in steps S2 and S3 is ultrasonic dispersion, and the dispersion time is 20 minutes to 60 minutes.

[0026] The purpose of the drying method involved in the present invention is to reduce the moisture content of the substance and control the moisture content of the dried substance to no more than 10%. Conventional drying methods in the art, such as vacuum drying, freeze drying, spray drying, oven drying, etc., can be used. Therefore, the specific implementation method is not limited. As described in steps S1 and S3, the drying is vacuum drying at a temperature of 70°C to 90°C and a drying time of 10h to 14h. The drying described in step S2 is freeze drying.

[0027] In a second aspect, the present invention provides a method for preparing the above-mentioned fluorine-functionalized composite ceramic membrane, comprising the following steps: dispersing the fluorine-functionalized ZIF-67 complex in a dimethyl sulfoxide solution, loading it onto the surface of the ceramic membrane by suction filtration, and drying it.

[0028] In some embodiments, the concentration of the dimethyl sulfoxide solution is 4 mM-10 mM.

[0029] In some embodiments, the drying temperature is 70° C.-90° C., and the drying time is 10 h-16 h.

[0030] In a third aspect, the present invention provides the use of the above-mentioned fluorine-functionalized ZIF-67 composite and fluorine-functionalized composite ceramic membrane in removing perfluorinated compounds in water.

[0031] In some embodiments, the perfluorinated compound includes at least one of perfluorooctanoic acid (PFOA), perfluorobutyric acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoro(2-methyl-3-oxahexanoic acid)ammonium (GenX), perfluorohexanesulfonic acid (PFHxS), and perfluorobutanesulfonic acid (PFBS); preferably at least one of PFOA, PFBA, GenX, and PFHxS.

[0032] In some embodiments, the concentration of perfluorinated compounds in the water body is 0.1 μg / L-100 mg / L.

[0033] In a fourth aspect, the present invention provides a defluorination device comprising an electrocatalytic reaction system having the above-mentioned fluorine-functionalized composite ceramic membrane as a cathode and a Pt-Ti plate as an anode.

[0034] In some embodiments, the defluorination device is a cross-flow filtration reaction device.

[0035] In some embodiments, the cross-flow filtration reaction device comprises a circulating liquid storage tank, a circulating chamber, a cathode, an anode, a power supply, and a treatment liquid storage tank;

[0036] The circulation chamber is provided with a water inlet, a circulating liquid outlet and a treated liquid outlet, the water inlet and the circulating liquid outlet are respectively connected to the circulating liquid storage tank through pipes, and the treated liquid outlet is connected to the treated liquid storage tank through a pipe;

[0037] A cathode and an anode are provided in the circulation chamber, and the cathode and the anode are connected to the negative electrode and the positive electrode of the power supply respectively to form an electrocatalytic reaction system;

[0038] The material of the cathode is a fluorine-functional composite ceramic membrane, and the material of the anode is a porous Pt-Ti plate.

[0039] In a fourth aspect, the present invention provides a method for removing perfluorinated compounds from water, comprising the following steps:

[0040] The fluorine-functionalized composite ceramic membrane is used as the cathode and the Pt-Ti plate is used as the anode to carry out an electrochemical defluorination reaction on water containing perfluorinated compounds and sodium sulfate.

[0041] In some embodiments, the concentration of the perfluorocompound is 0.1 μg / L-100 mg / L, and the concentration of the sodium sulfate is 0.01M-0.5M.

[0042] In some embodiments, the current density of the electrochemical defluorination reaction is 5 mA / cm²-100 mA / cm 2 .

[0043] In some embodiments, the flow rate of the water body is 5 mL / min-100 mL / min.

[0044] The present invention takes the fluorine-functionalized ZIF-67 composite ceramic membrane cathode as the core, and cooperates with a cross-flow filtration reaction device to significantly improve the defluorination efficiency of trace PFASs through the "adsorption-reduction" mechanism coupling. It has the adaptability to complex water bodies, the advantages of low interfacial resistance energy consumption and long-term operation stability, and provides an integrated solution for the efficient removal of perfluorinated pollutants in wastewater.

[0045] Compared with the prior art, the present invention has the following advantages:

[0046] 1. Efficient adsorption-reduction synergy: Fluorine-functionalized design enables selective adsorption and simultaneous electrocatalytic reduction of trace PFASs pollutants, significantly improving pollutant removal efficiency;

[0047] 2. Potential for low-energy operation: The close integration of the ceramic substrate and the fluorine-functionalized ZIF-67 composite reduces the electrode spacing by 1 to 2 orders of magnitude compared to conventional electrodes, significantly reducing interfacial resistance and making it particularly suitable for low-conductivity wastewater treatment.

[0048] 3. Enhanced structural stability: The strong bond between the ceramic membrane and the catalytic material (fluorine-functionalized ZIF-67 complex) prevents the loss of active components and ensures long-term operational stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a schematic structural diagram of the cross-flow filtration reaction device of the present invention.

[0050] Among them, 1. circulating liquid storage tank; 2. water inlet pipe; 3. pump; 4. water inlet; 5. circulation chamber; 6. fluorine-functionalized composite ceramic membrane cathode; 7. porous Pt-Ti anode; 8. treatment liquid outlet; 9. treatment liquid outlet pipe; 10. treatment liquid storage tank; 11. circulating liquid outlet; 12. power supply.

[0051] Figure 2 This is the full XPS spectrum of the fluorine-functionalized ZIF-67 composite powder in Example 1.

[0052] Figure 3 These are high-magnification SEM images and low-magnification SEM images of the fluorine-functionalized ZIF-67 composite ceramic membrane in Example 1.

[0053] Figure 4 This is the EDS image of the fluorine-functionalized ZIF-67 composite ceramic membrane in Example 1. DETAILED DESCRIPTION

[0054] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described below in conjunction with specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0055] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0056] Unless otherwise specified, the solvent for preparing the solution in the present invention is deionized water and the temperature is room temperature (20° C.-25° C.).

[0057] Example 1

[0058] A fluorine-functionalized ZIF-67 ceramic membrane is prepared by:

[0059] S1. Dissolve 2.9 g of Co(NO3)2·6H2O in 100 mL of methanol to form solution A. Dissolve 6.5 g of 2-methylimidazole in 100 mL of methanol to form solution B. Quickly pour solution B into solution A, stir at room temperature for 1 h, then let it stand for 24 h of aging, collect the purple precipitate by centrifugation, wash it three times with methanol, and dry it in vacuum at 80°C for 12 h to obtain the ZIF-67 precursor.

[0060] S2. Take 350 mg of ZIF-67 precursor and disperse it in 5 mL of ethanol. Add 100 μL of pentafluorobenzenethiol and 10 mL of ethanol. After ultrasonic dispersion for 30 minutes, heat and react at 85°C for 14 hours. After the reaction is completed, wash it with ethanol and deionized water three times in sequence, and freeze-dry to obtain fluorine-functionalized ZIF-67.

[0061] S3. Disperse 40 mg of reduced graphene oxide in 50 mL of deionized water and ultrasonically treat for 30 min to form a uniform dispersion. Add 200 mg of fluorine-functionalized ZIF-67 and continue ultrasonic dispersion for 30 min. Then collect the complex by vacuum filtration, wash it three times with deionized water, and dry it at 80°C for 12 h to obtain a fluorine-functionalized ZIF-67 complex.

[0062] S4. Disperse 15 mg of fluorine-functionalized ZIF-67 complex in DMSO (5 mM) solution, ultrasonically treat for 2 h to form a uniform dispersion, and directionally load the dispersion onto the surface of the ceramic membrane by vacuum filtration. Dry at 85°C for 12 h to obtain a fluorine-functionalized ZIF-67 ceramic membrane.

[0063] Figure 2 This is the full XPS spectrum of the fluorine-functionalized ZIF-67 composite powder in Example 1. Characteristic peaks of elements such as F and Co can be seen from the figure, indicating that fluorine element is successfully doped into ZIF-67.

[0064] Figure 3 These are the high-magnification SEM and low-magnification SEM images of the fluorine-functionalized ZIF-67 composite ceramic membrane in Example 1. It can be seen from the figures that there are irregular flaky structures on the ceramic membrane substrate, which are evenly distributed on the surface of the ceramic membrane, indicating that the active components are successfully loaded onto the ceramic membrane.

[0065] Figure 4 This is the EDS image of the fluorine-functionalized ZIF-67 composite ceramic membrane in Example 1. In the image, Al comes from the alumina ceramic membrane substrate, and the presence of F and Co elements further proves that the catalyst is successfully loaded on the ceramic membrane.

[0066] A defluorination device, such as Figure 1 As shown, it includes a circulating liquid storage tank 1, a circulating chamber 5, a fluorine-functionalized composite ceramic membrane cathode 6, a porous Pt-Ti anode 7, a power supply 12, and a treatment liquid storage tank 10;

[0067] The circulation chamber 5 is provided with a water inlet 4, a circulating liquid outlet 11 and a treated liquid outlet 8. The water inlet 4 and the circulating liquid outlet 11 are respectively connected to the circulating liquid storage tank 1 through pipes, and the treated liquid outlet 8 is connected to the treated liquid storage tank 10 through a treated liquid outlet pipe 9.

[0068] The circulation chamber 5 is provided with a fluorine-functionalized composite ceramic membrane cathode 6 and a porous Pt-Ti anode 7. The fluorine-functionalized composite ceramic membrane cathode 6 and the porous Pt-Ti anode 7 are respectively connected to the negative electrode and the positive electrode of the power supply 12 to form an electrocatalytic reaction system.

[0069] The circulating liquid storage tank 1 is connected to the pump 3 through a water inlet pipe 2, and the pump 3 is connected to the water inlet 4 through a pipeline.

[0070] A method for removing PFOA from water, using a defluorination device such as Figure 1 As shown, a fluorine-functionalized composite ceramic membrane is used as the cathode, an alumina ceramic membrane is used with a thickness of 3 mm and a pore size of 100 nm, a porous Pt-Ti plate is used as the anode, and a treatment liquid storage tank 10 is placed under the defluorination device to collect the reaction products.

[0071] Experimental parameters were as follows: a 0.1 M Na₂SO₄ solution containing 10 μg / L PFOA was continuously pumped into the defluorination device at a flow rate of 10 mL / min via a peristaltic pump. The power supply was set to constant current mode, applying a current density of 10 mA / cm² to initiate the reaction.

[0072] After testing, the PFOA removal rate was 97.5% and the PFOA defluorination rate was 97.0%.

[0073] After 10 repeated experiments, the defluorination rate remained at 97.5%.

[0074] Example 2

[0075] A fluorine-functionalized ZIF-67 ceramic membrane is prepared by:

[0076] S1. Dissolve 2.9 g of Co(NO₃)₂·6H₂O in 100 mL of methanol to form Solution A. Separately, dissolve 5.8 g of 2-methylimidazole in 100 mL of methanol to form Solution B. Quickly pour Solution B into Solution A, stir at room temperature for 1.5 h, and then allow to age for 24 h. Collect the purple precipitate by centrifugation, wash three times with methanol, and dry under vacuum at 75°C for 13 h to obtain the ZIF-67 precursor.

[0077] S2. Take 350 mg of ZIF-67 precursor and disperse it in 5 mL of ethanol. Add 110 μL of pentafluorobenzenethiol and 10 mL of ethanol. After ultrasonic dispersion for 30 minutes, heat and react at 85°C for 12 hours. After the reaction is completed, wash it with ethanol and deionized water three times in sequence, and freeze-dry to obtain fluorine-functionalized ZIF-67.

[0078] S3. Disperse 40 mg of reduced graphene oxide in 50 mL of deionized water and ultrasonically treat for 30 min to form a uniform dispersion; add 180 mg of fluorine-functionalized ZIF-67, continue ultrasonic dispersion for 30 min, and then collect the complex by vacuum filtration, wash three times with deionized water, and dry at 70°C for 12 h to obtain a fluorine-functionalized ZIF-67 complex.

[0079] S4. Disperse 15 mg of fluorine-functionalized ZIF-67 complex in DMSO (6 mM) solution, ultrasonically treat for 2 h to form a uniform dispersion, and directionally load the dispersion onto the surface of the ceramic membrane by vacuum filtration. Dry at 70°C for 14 h to obtain a fluorine-functionalized ZIF-67 ceramic membrane.

[0080] A method for removing PFBA from water, using a defluorination device such as Figure 1 As shown, a fluorine-functionalized composite ceramic membrane is used as the cathode, a zirconia ceramic membrane substrate is used with a thickness of 4 mm and a membrane pore size of 50 nm, a porous Pt-Ti plate is used as the anode, and a treatment liquid storage tank 10 is placed under the defluorination device to collect the reaction products.

[0081] Experimental parameters were as follows: a 0.2 M Na₂SO₄ solution containing 100 μg / L PFBA was continuously pumped into the defluorination device at a flow rate of 20 mL / min via a peristaltic pump. The power supply was set to constant current mode, applying a current density of 15 mA / cm² to initiate the reaction.

[0082] After testing, the PFBA removal rate was 98.0% and the PFBA defluorination rate was 97.8%.

[0083] Example 3

[0084] A fluorine-functionalized ZIF-67 ceramic membrane is prepared by:

[0085] S1. Dissolve 2.9 g of Co(NO3)2·6H2O in 100 mL of methanol to form solution A. Separately, dissolve 6.6 g of 2-methylimidazole in 100 mL of methanol to form solution B. Pour solution B quickly into solution A, stir at room temperature for 1 h, then allow to stand for aging for 24 h. Collect the purple precipitate by centrifugation, wash it three times with methanol, and dry it in vacuo at 80 °C for 12 h to obtain the ZIF-67 precursor.

[0086] S2. Disperse 350 mg of ZIF-67 precursor in 5 mL of ethanol, add 100 μL of pentafluorothiophenol and 10 mL of ethanol, and ultrasonically disperse for 30 min. Heat the mixture at 85°C for 14 h. After the reaction is complete, wash the mixture three times with ethanol and deionized water, and freeze-dry to obtain fluorine-functionalized ZIF-67.

[0087] S3. Disperse 40 mg of reduced graphene oxide in 50 mL of deionized water and ultrasonically treat for 30 min to form a uniform dispersion; add 220 mg of fluorine-functionalized ZIF-67, continue ultrasonic dispersion for 30 min, then collect the complex by vacuum filtration, wash three times with deionized water, and dry at 80°C for 12 h to obtain a fluorine-functionalized ZIF-67 complex.

[0088] S4. Disperse 15 mg of fluorine-functionalized ZIF-67 complex in DMSO (8 mM) solution, ultrasonically treat for 2 h to form a uniform dispersion, and directionally load the dispersion onto the surface of the ceramic membrane by vacuum filtration. Dry at 80°C for 12 h to obtain a fluorine-functionalized ZIF-67 ceramic membrane.

[0089] A method for defluorinating GenX in a low-conductivity solution, using a defluorinating device such as Figure 1 As shown, a fluorine-functionalized composite ceramic membrane is used as the cathode, a titanium oxide ceramic membrane substrate is used with a thickness of 5 mm and a membrane pore size of 150 nm, a porous Pt-Ti plate is used as the anode, and a treatment liquid storage tank 10 is placed under the defluorination device to collect the reaction products.

[0090] Experimental parameters were as follows: a 0.05M Na₂SO₄ solution containing 1mg / L GenX was continuously pumped into the defluorination device at a flow rate of 50mL / min via a peristaltic pump. The power supply was set to constant current mode, applying a current density of 20mA / cm² to initiate the reaction.

[0091] After testing, the GenX removal rate was 97.0% and the GenX defluorination rate was 96.8%.

[0092] Example 4

[0093] A fluorine-functionalized ZIF-67 ceramic membrane is prepared by:

[0094] S1. Dissolve 2.9 g of Co(NO3)2·6H2O in 100 mL of methanol to form solution A. Separately, dissolve 6.1 g of 2-methylimidazole in 100 mL of methanol to form solution B. Pour solution B quickly into solution A, stir at room temperature for 1.2 h, then allow to stand for aging for 24 h, collect the purple precipitate by centrifugation, wash three times with methanol, and dry under vacuum at 85 °C for 14 h to obtain the ZIF-67 precursor.

[0095] S2. Disperse 350 mg of ZIF-67 precursor in 5 mL of ethanol, add 90 μL of pentafluorobenzenethiol and 10 mL of ethanol, and ultrasonically disperse for 30 min. Heat the mixture at 85°C for 14 h. After the reaction is complete, wash the mixture three times with ethanol and deionized water, and freeze-dry to obtain fluorine-functionalized ZIF-67.

[0096] S3. Disperse 40 mg of reduced graphene oxide in 50 mL of deionized water and ultrasonically treat for 30 min to form a uniform dispersion; add 210 mg of fluorine-functionalized ZIF-67, continue ultrasonic dispersion for 30 min, then collect the complex by vacuum filtration, wash three times with deionized water, and dry at 85°C for 12 h to obtain a fluorine-functionalized ZIF-67 complex.

[0097] S4. Disperse 15 mg of fluorine-functionalized ZIF-67 complex in DMSO (7 mM) solution, ultrasonically treat for 2 h to form a uniform dispersion, and directionally load the dispersion onto the surface of the ceramic membrane by vacuum filtration. Dry at 80°C for 12 h to obtain a fluorine-functionalized ZIF-67 ceramic membrane.

[0098] A method for removing PFHxS from water, using a defluorination device such as Figure 1 As shown, a fluorine-functionalized composite ceramic membrane is used as the cathode, a silicon oxide ceramic membrane substrate is used with a thickness of 5 mm and a membrane pore size of 200 nm, a porous Pt-Ti plate is used as the anode, and a treatment liquid storage tank 10 is placed under the defluorination device to collect the reaction products.

[0099] Experimental parameters were as follows: a pollutant solution containing 10 mg / L PFHxS and 0.1 M Na₂SO₄ was continuously pumped into the reactor inlet at a flow rate of 80 mL / min by a peristaltic pump. The power supply was set to constant current mode, applying a current density of 50 mA / cm² to initiate the reaction.

[0100] After testing, the PFHxS removal rate was 96.0% and the PFHxS defluorination rate was 95.6%.

[0101] Comparative Example 1

[0102] This comparative example differs from Example 1 in that no fluorine functionalization was performed during the preparation process, and the other reaction apparatus and experimental conditions were the same as those in Example 1;

[0103] A ZIF-67 ceramic membrane, specifically prepared by:

[0104] S1. Dissolve 2.9 g of Co(NO3)2·6H2O in 100 mL of methanol to form solution A. Separately, dissolve 6.5 g of 2-methylimidazole in 100 mL of methanol to form solution B. Quickly pour solution B into solution A, stir at room temperature for 1 h, then allow to stand for aging for 24 h, collect the purple precipitate by centrifugation, wash it three times with methanol, and dry it in vacuo at 80 °C for 12 h to obtain the ZIF-67 precursor.

[0105] S2. Disperse 40 mg of reduced graphene oxide in 50 mL of deionized water and ultrasonically treat for 30 min to form a uniform dispersion; add 200 mg of ZIF-67 precursor and continue ultrasonic dispersion for 30 min. Then, collect the complex by vacuum filtration, wash three times with deionized water, and dry at 80°C for 12 h to obtain a ZIF-67 complex.

[0106] S3. Disperse 15 mg of ZIF-67 complex in DMSO (5 mM) solution and ultrasonicate for 2 h to form a uniform dispersion. Directly load the dispersion onto the surface of the ceramic membrane by vacuum filtration and dry at 85 °C for 12 h to obtain the ZIF-67 ceramic membrane.

[0107] A method for removing PFOA from water, using a defluorination device such as Figure 1 As shown, a fluorine-functionalized composite ceramic membrane is used as the cathode, an alumina ceramic membrane is used with a thickness of 3 mm and a pore size of 100 nm, a porous Pt-Ti plate is used as the anode, and a treatment liquid storage tank 10 is placed under the defluorination device to collect the reaction products.

[0108] Experimental parameters were as follows: a 0.1M Na₂SO₄ solution containing 10 μg / L PFOA was continuously pumped into the defluorination device at a flow rate of 10 mL / min via a peristaltic pump. The power supply was set to constant current mode, applying a current density of 10 mA / cm² to initiate the reaction.

[0109] After testing, the PFOA removal rate was 30.0% and the PFOA defluorination rate was 29.5%.

[0110] Comparative Example 2

[0111] The difference between this comparative example and Example 1 is that the preparation method of the fluorine-functionalized composite ceramic membrane is different, and the other reaction devices and experimental conditions are the same as those in Example 1;

[0112] The fluorine-functionalized composite ceramic membrane of the present invention is prepared by the preparation method of Example 1 in Chinese Patent Publication No. CN119746930A. The specific preparation method is as follows:

[0113] (1) Accurately weigh 1.161 g of maleic acid and 5.299 g of sodium carbonate, dissolve them in 20 mL of deionized water, ultrasonicate for 8 min, dry at 50 °C for 12 h, take out the dried solid and grind it thoroughly. Move the ground powder into a tube furnace, and heat it to 650 °C at a rate of 5 °C / min for 3 h in an argon atmosphere with a flow rate of 50 mL / min. The product is washed with anhydrous ethanol and deionized water, respectively, and dried in a vacuum at 50 °C for 12 h to obtain porous graphene.

[0114] (2) Accurately weigh 0.436 g of cobalt nitrate hexahydrate and dissolve it in 50 mL of ultrapure water. Stir and mix evenly for 10 min. Add 0.1 g of porous graphene and ultrasonically treat to obtain solution A. Accurately weigh 0.517 g of 2-methylimidazole and 0.105 g of 2-trifluoromethylimidazole and dissolve them in 50 mL of methanol. Ultrasonicate for 10 min to obtain solution B.

[0115] (3) Solution B was slowly added dropwise to solution A while stirring. After standing for 24 hours, the mixture was centrifuged. The precipitate was washed with methanol and deionized water respectively, and dried under vacuum at 50°C for 12 hours to obtain a composite catalyst.

[0116] (4) 15 mg of the composite catalyst was dispersed in DMSO (5 mM) solution and ultrasonically treated for 2 h to form a uniform dispersion. The dispersion was directionally loaded onto the surface of the ceramic membrane by vacuum filtration and dried at 85 °C for 12 h to obtain a fluorine-functionalized ZIF-67 ceramic membrane.

[0117] A method for removing PFOA from water, using a defluorination device such as Figure 1 As shown, a fluorine-functionalized composite ceramic membrane is used as the cathode, an alumina ceramic membrane is used with a thickness of 3 mm and a pore size of 100 nm, a porous Pt-Ti plate is used as the anode, and a treatment liquid storage tank 10 is placed under the defluorination device to collect the reaction products.

[0118] Experimental parameters were as follows: a 0.1M Na₂SO₄ solution containing 10 μg / L PFOA was continuously pumped into the defluorination device at a flow rate of 10 mL / min via a peristaltic pump. The power supply was set to constant current mode, applying a current density of 10 mA / cm² to initiate the reaction.

[0119] After testing, the PFOA removal rate was 40.0% and the PFOA defluorination rate was 39.5%.

[0120] The above further describes the present invention in conjunction with specific embodiments. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solutions of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, and such modifications and replacements shall fall within the scope of protection of the present invention.

Claims

1. A fluorine-functionalized composite ceramic membrane, characterized in that: It includes a ceramic membrane and a catalyst loaded on the surface of the ceramic membrane, wherein the catalyst is a fluorine-functionalized ZIF-67 complex; The catalyst loading is 0.2 mg / cm²-0.5 mg / cm²; The material of the ceramic membrane is one of aluminum oxide, zirconium oxide, titanium oxide or silicon oxide; The preparation method of the fluorine-functionalized ZIF-67 complex comprises the following steps: S1. Dissolving cobalt nitrate hexahydrate in methanol to form solution A; dissolving 2-methylimidazole in methanol to form solution B; mixing the solution B with the solution A, stirring, aging, solid-liquid separation, washing, and drying to obtain a ZIF-67 precursor; S2, adding ethanol and pentafluorobenzenethiophenol to the ZIF-67 precursor, dispersing, heating for reaction, washing and drying to obtain fluorine-functionalized ZIF-67; S3. Mixing and dispersing the reduced graphene oxide with water to obtain a dispersion; adding the fluorine-functionalized ZIF-67 to the dispersion, performing secondary dispersion, solid-liquid separation, washing and drying to obtain a fluorine-functionalized ZIF-67 complex.

2. The fluorine-functionalized composite ceramic membrane according to claim 1, characterized in that: The pore size of the ceramic membrane is 50nm-200nm.

3. The fluorine-functionalized composite ceramic membrane according to claim 1, characterized in that: The molar ratio of cobalt nitrate hexahydrate to 2-methylimidazole in step S1 is 1:5-10.

4. The fluorine-functionalized composite ceramic membrane according to claim 1, characterized in that: The aging time in step S1 is 20h-30h; And / or the heating reaction in step S2 is: reacting at 80°C-90°C for 10h-14h.

5. The method for preparing the fluorine-functionalized composite ceramic membrane according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: dispersing the fluorine-functionalized ZIF-67 complex in a dimethyl sulfoxide solution, loading the complex onto the surface of a ceramic membrane by suction filtration, and drying the mixture; The concentration of the dimethyl sulfoxide solution is 4 mM-10 mM.

6. Use of the fluorine-functionalized composite ceramic membrane according to any one of claims 1 to 4 in removing perfluorinated compounds from water, characterized in that: The perfluorinated compound includes at least one of perfluorooctanoic acid, perfluorobutyric acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoro(2-methyl-3-oxahexanoic acid)ammonium, perfluorohexanesulfonic acid, and perfluorobutanesulfonic acid; the removal method is: using the fluorine-functionalized composite ceramic membrane as the cathode and the Pt-Ti plate as the anode to perform an electrochemical defluorination reaction on the water containing the perfluorinated compound and sodium sulfate.

7. The use according to claim 6, characterized in that The concentration of the perfluorinated compound is 0.1 μg / L-100 mg / L.

8. A defluorination device, characterized in that: An electrocatalytic reaction system comprising the fluorine-functionalized composite ceramic membrane according to any one of claims 1 to 4 as a cathode and a Pt-Ti plate as an anode; The defluorination device is a cross-flow filtration reaction device.

9. A method for removing perfluorinated compounds from water, characterized in that: The following steps are involved: The fluorine-functionalized composite ceramic membrane according to any one of claims 1 to 4 is used as a cathode and a Pt-Ti plate is used as an anode to carry out an electrochemical defluorination reaction on water containing perfluorinated compounds and sodium sulfate.

10. The method for removing perfluorinated compounds in water according to claim 9, characterized in that: The concentration of the perfluorinated compound is 0.1 μg / L-100 mg / L, and the concentration of the sodium sulfate is 0.01M-0.5M; and / or the current density of the electrochemical defluorination reaction is 5 mA / cm 2 -100mA / cm 2 ; And / or the flow rate of the water body is 5 mL / min-100 mL / min.

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