PVDF / CA-Ag-MOF composite filter material as well as preparation method and application thereof

Abstract

The invention relates to a PVDF / CA (Polyvinylidene Fluoride)-Ag-MOF (Polyvinylidene Fluoride) composite filter material as well as a preparation method and application thereof. The preparation method comprises the following steps: providing an Ag-MOF material; mixing polyvinylidene fluoride, cellulose acetate and a first organic solvent to prepare a mixed solution; the Ag-MOF material is dispersed in the mixed solution, and a spinning precursor solution is prepared; and carrying out electrostatic spinning on the spinning precursor solution, and drying to obtain the composite material. Polyvinylidene fluoride (PVDF) / cellulose acetate (CA) / organic solvent / Ag-MOF materials are used as raw materials to prepare a spinning precursor solution, the PVDF / CA-Ag-MOF composite filter material can be prepared after a specific process is adopted, the PVDF / CA-Ag-MOF composite filter material has stable and lasting static electricity and good heat resistance, enhanced filtration of radioactive substances including Po-210 aerosol can be achieved, and the filter material can be applied to the field of chemical engineering. The inhalation amount of Po-210 aerosol and the like by people is effectively reduced, the safety of the people is guaranteed, and the comfort of the people is improved. In addition, the Ag-MOF has a relatively large specific surface area, so that the reaction area of the Ag-MOF to the Po-210 is increased, and a relatively good Po-210 adsorption effect is shown.

Description

Technical Field

[0001] The present application relates to the technical field of filter materials, and in particular to a PVDF / CA@Ag-MOF composite filter material and a preparation method and application thereof. Background Art

[0002] During the operation of the lead-bismuth reactor, the activation of the coolant will produce radioactive Po-210. Po-210 is a pure alpha nuclide. Its toxicity mainly comes from chemical toxicity and radioactive toxicity from internal irradiation. Po-210 in the gas may exist in two forms: aerosol and gas. It has a strong ionization ability. If it is inhaled, ingested or ingested through skin contact, it will cause internal contamination, poisoning or acute radiation sickness. If the needle absorption dose in the human body reaches 4Gy in a short period of time, it can cause fatal harm. Therefore, reducing the inhalation or skin contact of personnel with Po-210 in the gas is the most important means to prevent Po-210 personnel hazards. Summary of the invention

[0003] Based on this, it is necessary to develop a PVDF / CA@Ag-MOF composite filter material that can achieve enhanced filtration of radioactive substances including Po-210 aerosols.

[0004] The technical solution of this application is as follows:

[0005] The first aspect of the present invention provides a method for preparing a PVDF / CA@Ag-MOF composite filter material, comprising the following steps:

[0006] Provide Ag-MOF materials;

[0007] Mixing polyvinylidene fluoride, cellulose acetate and a first organic solvent to prepare a mixed solution;

[0008] Dispersing the Ag-MOF material in the mixed solution to prepare a spinning precursor solution;

[0009] The spinning precursor solution is subjected to electrostatic spinning and then dried to obtain the product.

[0010] In one embodiment, the weight percentage of the polyvinylidene fluoride to the cellulose acetate is 10%-90%.

[0011] In one embodiment, the weight percentage of the Ag-MOF material in the mixed solution is 0.5%-15%.

[0012] In one embodiment, the preparation of the Ag-MOF material comprises the following steps:

[0013] Silver nitrate, phthalic acid and a second organic solvent are mixed, stirred and heated for reaction; after the reaction is completed, the obtained precipitate is collected by filtration and dried.

[0014] In one embodiment, the preparation of the Ag-MOF material satisfies at least one of the following conditions:

[0015] (1) The molar ratio of silver nitrate to phthalic acid is 1:1-1:3;

[0016] (2) The stirring time is 0.5h-2h;

[0017] (3) The temperature of the heating reaction is 150°C-180°C;

[0018] (4) The heating reaction time is 8h-15h;

[0019] (5) The second organic solvent is N-N-dimethylformamide.

[0020] In one embodiment, the first organic solvent is a mixture of N-N-dimethylformamide and acetone;

[0021] Optionally, in the first organic solvent, the volume ratio of N-N-dimethylformamide to acetone is 1:1-1:3.

[0022] In one embodiment, the step of performing electrospinning satisfies at least one of the following conditions:

[0023] (1) Temperature is 20℃-50℃;

[0024] (2) Humidity: 10%-30%;

[0025] (3) Voltage is 5kV-15kV;

[0026] And / or, the drying step satisfies at least one of the following conditions:

[0027] (1) Temperature is 30℃-90℃;

[0028] (2) The time is 3h-12h.

[0029] The second aspect of the present invention provides a PVDF / CA@Ag-MOF composite filter material prepared according to the preparation method of the PVDF / CA@Ag-MOF composite filter material as described above.

[0030] The third aspect of the present invention provides the use of the PVDF / CA@Ag-MOF composite filter material as described above in pollution protection for processing aerosols.

[0031] In one embodiment, the aerosol is selected from ordinary aerosol, positively charged aerosol or alpha radionuclide aerosol;

[0032] Optionally, the aerosol is Po-210.

[0033] Compared with the prior art, this application has the following beneficial effects:

[0034] The present application provides a method for preparing a PVDF / CA@Ag-MOF composite filter material based on electrostatic adsorption. A spinning precursor solution is prepared by using polyvinylidene fluoride (PVDF) / cellulose acetate (CA) / organic solvent / Ag-MOF material as raw materials. After adopting a specific process, a PVDF / CA@Ag-MOF composite filter material can be obtained. The PVDF / CA@Ag-MOF composite filter material has stable and lasting electrostatics and good heat resistance, can achieve enhanced filtration of radioactive substances including Po-210 aerosols, effectively reduce the amount of Po-210 aerosols and the like inhaled by personnel, ensure personnel safety, and improve the comfort of users.

[0035] In addition, Ag-MOF has a large specific surface area, which enhances the reaction area for Po-210, and exhibits a good adsorption effect on gaseous Po-210. The spun membrane of the present application can be used as a protective mask or aerosol clothing material, and has an enhanced capture effect on gaseous and aerosol forms of Po-210, and also has excellent protective effects on other common aerosols, positively charged aerosols, α-radionuclide aerosols or iodine aerosols. DETAILED DESCRIPTION

[0036] The present application will be further described in detail below in conjunction with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly understood.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0038] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0039] As used herein, "one or more" refers to any one, any two, or any two or more of the listed items.

[0040] Herein, the optional scope of "and / or", "or / and", and "and / or" includes any one of two or more relevant listed items, and also includes any and all combinations of the relevant listed items, wherein said any and all combinations include any two relevant listed items, any more relevant listed items, or a combination of all relevant listed items. (It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in the present application, the technical solution undoubtedly includes technical solutions that are all connected by "logical AND", and also undoubtedly includes technical solutions that are all connected by "logical OR". For example, "A and / or B" includes three parallel solutions of A, B and A+B. For another example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, technical solutions that are all connected by "logical OR"), and also includes any and all combinations of A, B, C, and D, that is, a combination of any two or any three of A, B, C, and D, and also includes a combination of four items of A, B, C, and D (that is, a technical solution that is all connected by "logical AND").)

[0041] Herein, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0042] Herein, "first aspect", "second aspect", "third aspect", "fourth aspect", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. In addition, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0043] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0044] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, and any upper limit can be combined with any other upper limit to form an undefined range. In addition, each separately disclosed point or single value itself can be combined with any other point or single value as a lower limit or upper limit or with other lower limits or upper limits to form an undefined range. The use of numerical ranges represented by endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0045] The percentage contents involved in this application, unless otherwise specified, refer to mass percentage for solid-liquid mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0046] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0047] The temperature parameters in this application, unless otherwise specified, allow both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±2°C, ±1°C, ±0.5°C, ±0.4°C, ±0.3°C, ±0.2°C, and ±0.1°C are allowed. Normal temperature or room temperature in this application refers to no temperature control operation, generally 4°C to 35°C, preferably 20±5°C.

[0048] The existing means of radioactive contamination protection are mainly the following:

[0049] Existing protective mask filter membrane: At present, protective masks mostly use polypropylene (PP) filter membranes, which are mainly based on physical filtration to block particulate matter, and the filtration efficiency of 0.3 microns is 95%. The filter membrane has general filtration efficiency and cannot filter gaseous substances. CN202311659685.6 discloses a PVDF filter cotton and its preparation method and application, which is characterized in that the PVDF film is made into silk and then air-blown, spread, and heated to make PVDF filter cotton. It has the characteristics of a relatively simple preparation method, a high dielectric constant, a good filtration effect, and a good filtration effect for 0.3μm particles. However, the filter membrane of this method has weak electrostatics, mainly relying on physical interception filtration, and it is difficult to capture gaseous Po-210. In summary, existing protective masks mostly use physical interception filtration or use electrets to add charges to the surface of the filter membrane, and there are defects such as no electrostatic effect or rapid electrostatic decay.

[0050] CN202310052091.2 discloses a high-efficiency, low-resistance multifunctional composite membrane air purification material and its preparation process, which is characterized in that a dust holding layer and a filter membrane layer are combined into one by bonding particles and a support layer under hot pressing, and have the advantages of no static attenuation, large dust holding capacity, high efficiency and low resistance, and can effectively intercept particulate matter and microbial aerosols in the air, and can quickly kill intercepted bacteria, viruses, and microbial aerosols to prevent secondary pollution. However, the filter layer of the filter membrane is made of materials such as PVDF, PAN, PA, PES, PU, ​​PLA, and PS, and the static electricity of such materials is limited, and the water vapor permeability of materials such as PVDF is weak, which reduces its physiological comfort as a personnel protection material. In summary, the prior art mainly filters aerosols alone, does not remove gaseous nuclides at the same time, and does not remove gaseous Po-210.

[0051] CN202410233075.8 provides a piezoelectric enhanced PVDF nanofiber air filter membrane and a preparation method thereof, the main feature of which is to dissolve PVDF and piezoelectric enhanced polymers into a good solvent respectively, and prepare a piezoelectric enhanced high-efficiency filtration PVDF nanocomposite fiber membrane in one step. The invention has a simple preparation process, is easy to operate, and has a short process. The obtained filter membrane can spontaneously generate charges during the air filtration process, enhance the electrostatic adsorption function, and improve the particle filtration efficiency. However, this method only discloses the preparation and application of the electrostatic filter membrane, does not have the adsorption characteristics of gaseous Po simple substances and compounds, and is not designed for the electrostatic enhancement of the filter membrane and the physiological comfort of the PVDF-based spinning filter membrane.

[0052] In order to solve the problem of protecting Po-210 aerosol and gaseous compounds in air space, the technical personnel of this application proposed a method for preparing Po-210 high-efficiency filter material after extensive research: this application proposes a polonium aerosol purification method based on electrostatic adsorption, based on the characteristic that Po-210 is a pure alpha decay nuclide and has a strong electrostatic charge on the surface of Po-210 aerosol due to the decay effect. By preparing a spinning membrane with stable electrostatics, enhanced filtration of Po-210 aerosol is achieved.

[0053] The first aspect of the present invention provides a method for preparing a PVDF / CA@Ag-MOF composite filter material, comprising the following steps:

[0054] Provide Ag-MOF materials;

[0055] Mixing polyvinylidene fluoride, cellulose acetate and a first organic solvent to prepare a mixed solution;

[0056] Dispersing the Ag-MOF material in the mixed solution to prepare a spinning precursor solution;

[0057] The spinning precursor solution is subjected to electrostatic spinning and then dried to obtain the product.

[0058] In some examples, the weight percentage of the polyvinylidene fluoride in cellulose acetate is 10%-90%. Further, the weight percentage of the polyvinylidene fluoride in cellulose acetate is 10%-30%. It is understandable that the weight percentage of the polyvinylidene fluoride in cellulose acetate includes but is not limited to 10%, 15%, 20%, 25%, 30%.

[0059] In some examples, the weight percentage of the Ag-MOF material in the mixed solution is 0.5%-15%. Further, the weight percentage of the Ag-MOF material in the mixed solution is 0.5%-5%. It is understandable that the weight percentage of the Ag-MOF material in the mixed solution includes but is not limited to 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%.

[0060] In some examples, the preparation of the Ag-MOF material includes the following steps:

[0061] Silver nitrate, phthalic acid and a second organic solvent are mixed, stirred and heated for reaction; after the reaction is completed, the obtained precipitate is collected by filtration and dried.

[0062] At the same time, the protection against gaseous Po-210 is not limited to the Ag-MOF material of the present application, and Ag-MOF or single silver nanoparticles or single silver-loaded materials prepared by other means can achieve similar effects;

[0063] In some examples, the preparation conditions of the Ag-MOF material include: the molar ratio of silver nitrate to phthalic acid is 1:1-1:3. It is understood that the molar ratio of silver nitrate to phthalic acid includes but is not limited to 1:1, 1:1.5, 1:2, 1:2.5, 1:3

[0064] In some examples, the preparation conditions of the Ag-MOF material include: the stirring time is 0.5h-2h. It can be understood that the preparation conditions of the Ag-MOF material include: the stirring time includes but is not limited to 0.5h, 1h, 1.5h, 2h.

[0065] In some examples, the preparation conditions of the Ag-MOF material include: the temperature of the heating reaction is 150° C.-180° C. It can be understood that the preparation conditions of the Ag-MOF material include: the temperature of the heating reaction includes but is not limited to 150° C., 155° C., 160° C., 165° C., 170° C., 175° C., 180° C.

[0066] In some examples, the preparation conditions of the Ag-MOF material include: the heating reaction time is 8h-15h. It can be understood that the preparation conditions of the Ag-MOF material include: the heating reaction time includes but is not limited to 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h.

[0067] In some examples, the Ag-MOF material is dispersed in the mixed solution by one or more of stirring or ultrasound.

[0068] In some examples, the first organic solvent is a mixture of N-N-dimethylformamide and acetone.

[0069] In some examples, the volume ratio of N-N-dimethylformamide to acetone in the first organic solvent is 1:1-1:3. It is understandable that the volume ratio of N-N-dimethylformamide to acetone in the first organic solvent includes but is not limited to 1:1, 1:1.5, 1:2, 1:2.5, 1:3.

[0070] In some examples, the second organic solvent is NN dimethylformamide.

[0071] In some examples, the conditions for performing electrospinning include: a temperature of 20° C.-50° C. It can be understood that the temperature for performing electrospinning includes but is not limited to 20° C., 25° C., 30° C., 35° C., 40° C., 45° C., and 50° C.

[0072] In some of the examples, the conditions for electrospinning include: humidity of 10%-30%. It is understood that the humidity for electrospinning includes but is not limited to 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%.

[0073] In some examples, the conditions for electrospinning include: a voltage of 5 kV-15 kV. It can be understood that the voltage for electrospinning includes but is not limited to 5 kV, 6 kV, 7 kV, 8 kV, 9 kV, 10 kV, 11 kV, 12 kV, 13 kV, 14 kV, and 15 kV.

[0074] In some examples, the drying step is performed under conditions of 30° C.-90° C. It is understood that the drying temperature includes but is not limited to 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., and 90° C.

[0075] In some examples, the conditions for performing the drying step include: a time of 3h-12h. It is understandable that the time for performing the drying step includes but is not limited to 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h, 12h.

[0076] In addition, the spinning method is not limited to doping Ag-MOF into the spinning precursor. Similar effects can also be achieved by coaxial spinning or loading Ag-MOF on the surface of PVDF / CA membrane.

[0077] The second aspect of the present invention provides a PVDF / CA@Ag-MOF composite filter material prepared according to the preparation method of the PVDF / CA@Ag-MOF composite filter material as described above.

[0078] Specifically, the present application proposes a PVDF / CA@Ag-MOF electrospinning membrane, which has the following advantages:

[0079] (1) The spinning membrane has enhanced and lasting static electricity, which comes from the structural polarity of PVDF. Therefore, it does not need to be provided by an electret, and the static electricity is not easy to decay;

[0080] (2) Based on CA composite, the β-phase ratio of PVDF is increased, thereby enhancing the polarity of the PVDF structure and the electrostatic effect of the spinning membrane.

[0081] (3) CA composite reduces the hydrophobicity of PVDF fibers, thereby making the composite material have better water vapor permeability and enhancing its physiological comfort as a personal protective material such as masks.

[0082] (4) The composite spinning of Ag-MOF materials makes the filter membrane have a finer diameter, enhances the surface roughness of the fiber, and achieves a better adsorption effect. Together with the large specific surface area and strong binding properties of the Ag-MOF material, it achieves excellent adsorption performance for gaseous compounds.

[0083] The third aspect of the present invention provides the use of the PVDF / CA@Ag-MOF composite filter material as described above in pollution protection for treating aerosols.

[0084] In some of these examples, the aerosol is selected from ordinary aerosol, positively charged aerosol or alpha radionuclide aerosol.

[0085] In some of the examples, the aerosol is Po-210. Specifically, α-nuclides such as Po-210 will cause their aerosols to be positively charged due to their decay process, so the PVDF / CA@Ag-MOF composite filter material described in this application is negatively charged and can enhance adsorption through electrostatic effect. In addition, silver MOF can also enhance the adsorption of Po aerosol and gaseous Po.

[0086] In some of these examples, the application refers to using the PVDF / CA@Ag-MOF composite filter material described above in protective equipment such as protective masks and air suits.

[0087] The following is further described in conjunction with specific embodiments. The raw materials involved in the following specific embodiments, unless otherwise specified, can all be commercially available; the instruments used, unless otherwise specified, can all be commercially available; the processes involved, unless otherwise specified, are all routinely selected by those skilled in the art.

[0088] The preparation method of silver MOF is as follows:

[0089] AgNO3 and p-phthalic acid (PTA) were dissolved in DMF solution at a molar ratio of 1:1 and stirred continuously for 1 h in the dark to achieve uniform mixing.

[0090] The prepared mixture was transferred into a reaction vessel and heated at 150°C-180°C for 8-15 hours.

[0091] After the reactor was cooled, it was washed twice with DMF and the precipitate was collected by vacuum filtration. The trapped material was placed in an oven and dried at 60 °C for 18 h to remove unreacted reagents and residual impurities.

[0092] The following are specific embodiments.

[0093] Example 1

[0094] (1) Mix polyvinylidene fluoride (PVDF) and cellulose acetate (CA) in a ratio of 15% and slowly dissolve them in a beaker containing a mixture of N-dimethylformamide (DMF) and acetone (volume ratio 1:1), and stir for a certain period of time to fully dissolve them;

[0095] (2) weighing a certain weight ratio of Ag-MOF material (1%), adding it to the above-mentioned dissolving solution, and using stirring, ultrasound and other methods to fully disperse the Ag-MOF powder to prepare a spinning precursor solution;

[0096] (3) injecting the prepared spinning precursor solution into a syringe with a nozzle and fixing it on an electrospinning device, and setting the electrospinning parameters to a temperature of 40° C., a humidity of 30%, a receiving distance of 17 cm, a push injection speed of 1 mL / h, and a voltage of 8 kV, and a nanofiber membrane can be prepared through an electrospinning process;

[0097] (4) The precursor fiber membrane is placed in a forced air drying oven for drying at a drying temperature of 80°C and a holding time of 6 hours.

[0098] Example 2

[0099] (1) Mix polyvinylidene fluoride (PVDF) and cellulose acetate (CA) in a ratio of 30% and slowly dissolve them in a beaker containing a mixture of N-dimethylformamide (DMF) and acetone (volume ratio 1:1), and stir for a certain period of time to fully dissolve them;

[0100] (2) weighing a certain weight ratio of Ag-MOF material (1%), adding it to the above-mentioned dissolving solution, and using stirring, ultrasound and other methods to fully disperse the Ag-MOF powder to prepare a spinning precursor solution;

[0101] (3) injecting the prepared spinning precursor solution into a syringe with a nozzle and fixing it on an electrospinning device, and setting the electrospinning parameters to a temperature of 40° C., a humidity of 30%, a receiving distance of 17 cm, a push injection speed of 1 mL / h, and a voltage of 8 kV, and a nanofiber membrane can be prepared through an electrospinning process;

[0102] (4) The precursor fiber membrane is placed in a forced air drying oven for drying at a drying temperature of 80°C and a holding time of 6 hours.

[0103] Example 3

[0104] (1) Mix polyvinylidene fluoride (PVDF) and cellulose acetate (CA) in a certain ratio (15%) and slowly dissolve them in a beaker containing a mixture of N-dimethylformamide (DMF) and acetone (volume ratio 1:1), and stir for a certain period of time to fully dissolve them;

[0105] (2) weighing a certain weight ratio of Ag-MOF material (5%), adding it to the above-mentioned dissolving solution, and using stirring, ultrasound and other methods to fully disperse the Ag-MOF powder to prepare a spinning precursor solution;

[0106] (3) injecting the prepared spinning precursor solution into a syringe with a nozzle and fixing it on an electrospinning device, and setting the electrospinning parameters to a temperature of 40° C., a humidity of 30%, a receiving distance of 17 cm, a push injection speed of 1 mL / h, and a voltage of 8 kV, and a nanofiber membrane can be prepared through an electrospinning process;

[0107] (4) The precursor fiber membrane is placed in a forced air drying oven for drying at a drying temperature of 80°C and a holding time of 6 hours.

[0108] Comparative Example 1

[0109] Comparative Example 1 is basically the same as Example 1, except that CA compounding and Ag-MOF doping are not performed in the comparative example.

[0110] (1) Slowly dissolve polyvinylidene fluoride (PVDF) in a beaker containing a mixture of N-dimethylformamide (DMF) and acetone (volume ratio 1:1), and stir for a certain period of time to fully dissolve it;

[0111] (2) injecting the prepared spinning precursor solution into a syringe with a nozzle and fixing it on an electrospinning device, and setting the electrospinning parameters to a temperature of 40° C., a humidity of 30%, a receiving distance of 17 cm, a push injection speed of 1 mL / h, and a voltage of 8 kV, and a nanofiber membrane can be prepared through an electrospinning process;

[0112] (3) The precursor fiber membrane is placed in a forced air drying oven for drying at a drying temperature of 80°C and a holding time of 6 hours.

[0113] The performance tests of the Po-210 filter materials prepared in Examples 1-3 and Comparative Example 1 were performed as follows:

[0114] The static value was tested using an electrostatic field tester. Aerosol was generated by heating LBE-Te alloy, and the Te content in the filter membrane to be tested, the monitoring filter membrane, and the exhaust hand sanitizer was tested respectively. The filtration efficiency was calculated using the following formula:

[0115] DE = m / (m+m1+m2)×100%;

[0116] Wherein, DE: purification efficiency; m: Te content on the filter material; m1: Te content on the monitoring material; m2: Te content in the tail liquid.

[0117] The test results are shown in Table 1.

[0118] Table 1

[0119] serial number Static value (kV) Filtration efficiency (%) Heat resistance Example 1 -3.5 99.9 300℃ Example 2 -2.7 96 280℃ Example 3 -3 99.5 250℃ Comparative Example 1 -1.5 68 110℃

[0120] Through the above comparison, it is found that the change in the composite ratio of CA and Ag-MOF will have a significant impact on the static electricity value carried by the material. Under the ratio conditions of Example 1, the static electricity carried is the strongest, the filtration efficiency of Te can reach 99.9%, and the temperature resistance is good. In Comparative Example 1, due to the lack of CA and Ag-MOF modification, the static electricity value is significantly weaker than that of Examples 1-3, and the filtration efficiency and temperature resistance are also poor.

[0121] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims, and the description may be used to interpret the content of the claims.

Claims

1. A method for preparing a PVDF / CA@Ag-MOF composite filter material, characterized in that: The following steps are involved: Provide Ag-MOF materials; Mixing polyvinylidene fluoride, cellulose acetate and a first organic solvent to prepare a mixed solution; Dispersing the Ag-MOF material in the mixed solution to prepare a spinning precursor solution; The spinning precursor solution is subjected to electrostatic spinning and then dried to obtain the product.

2. The method for preparing the PVDF / CA@Ag-MOF composite filter material according to claim 1, characterized in that: The weight percentage of the polyvinylidene fluoride to cellulose acetate is 10%-90%.

3. The method for preparing the PVDF / CA@Ag-MOF composite filter material according to claim 1, characterized in that: The weight percentage of the Ag-MOF material in the mixed solution is 0.5%-15%.

4. The method for preparing the PVDF / CA@Ag-MOF composite filter material according to claim 1, characterized in that: The preparation of the Ag-MOF material comprises the following steps: Silver nitrate, phthalic acid and a second organic solvent are mixed, stirred and heated for reaction; after the reaction is completed, the obtained precipitate is collected by filtration and dried.

5. The method for preparing the PVDF / CA@Ag-MOF composite filter material according to claim 4, characterized in that: The preparation of the Ag-MOF material satisfies at least one of the following conditions: (1) The molar ratio of silver nitrate to phthalic acid is 1:1-1:3; (2) The stirring time is 0.5h-2h; (3) The temperature of the heating reaction is 150°C-180°C; (4) The heating reaction time is 8h-15h; (5) The second organic solvent is N-N-dimethylformamide.

6. The method for preparing the PVDF / CA@Ag-MOF composite filter material according to claim 4, characterized in that: The first organic solvent is a mixture of N-N-dimethylformamide and acetone; Optionally, in the first organic solvent, the volume ratio of N-N-dimethylformamide to acetone is 1:1-1:

3.

7. The method for preparing the PVDF / CA@Ag-MOF composite filter material according to claim 1, characterized in that: The step of performing electrospinning satisfies at least one of the following conditions: (1) Temperature is 20℃-50℃; (2) Humidity: 10%-30%; (3) Voltage is 5kV-15kV; And / or, the drying step satisfies at least one of the following conditions: (1) Temperature is 30℃-90℃; (2) The time is 3h-12h.

8. A PVDF / CA@Ag-MOF composite filter material prepared according to the preparation method of the PVDF / CA@Ag-MOF composite filter material according to any one of claims 1 to 7.

9. Use of the PVDF / CA@Ag-MOF composite filter material according to claim 8 in pollution protection for aerosol treatment.

10. The use according to claim 9, characterized in that: The aerosol is selected from ordinary aerosol, positively charged aerosol or alpha radionuclide aerosol; Optionally, the aerosol is Po-210.