CN116036867A

CN116036867A - Iron-based MOF material modified ultrafiltration membrane and preparation method and application thereof

Info

Publication number: CN116036867A
Application number: CN202310020875.7A
Authority: CN
Inventors: 张岚; 李峥; 贾丽娜; 陈姆妹; 郑小北
Original assignee: Shanghai Shenjing Pharmaceutical Technology Co ltd
Current assignee: Shanghai Shenjing Pharmaceutical Technology Co ltd
Priority date: 2023-01-06
Filing date: 2023-01-06
Publication date: 2023-05-02

Abstract

The invention discloses an iron-based MOF material modified ultrafiltration membrane and a preparation method and application thereof. The preparation method of the iron-based MOF material modified ultrafiltration membrane comprises the following steps: s1, under the condition that a solvent exists, crystallizing a mixture of ferric salt and 2-amino terephthalic acid to obtain an iron-based MOF material; wherein the mass ratio of the 2-amino terephthalic acid to the ferric salt is 3 (3-13); s2, sequentially adding an acrylic monomer and a PVDF film into the mixture containing the iron-based MOF material, and then carrying out ultrasonic mixing and irradiation reaction to obtain the iron-based MOF material. The iron-based MOF material modified ultrafiltration membrane has excellent flux, pH responsiveness and pollution resistance, and can effectively intercept Ce ³⁺ Solves the problems of the radioactive wastewater in pH and ion concentrationUnder the limitation of the degree and other conditions, the ultrafiltration membrane is less in complexing position to Ce ³⁺ The problem of reduced retention rate is that the radioactive wastewater treatment shows good filtration performance.

Description

Iron-based MOF material modified ultrafiltration membrane and preparation method and application thereof

Technical Field

The invention relates to an iron-based MOF material modified ultrafiltration membrane, and a preparation method and application thereof.

Background

In recent years, with the development of chemical industry, the treatment of radioactive waste water is increasingly emphasized as the occurrence of accident frequency related to the leakage of radioactive nuclear waste water. Currently, in waste solutions containing various radionuclides, the splinter products ¹⁴¹ Ce and ¹⁴⁴ ce is a well-known radionuclide contributing greatly to humans and therefore contains ¹⁴¹ Ce and ¹⁴⁴ the radioactive wastewater of Ce can be discharged after being treated. The existing radioactive wastewater treatment methods mainly comprise a precipitation method, an ion exchange method, an evaporation concentration method and a membrane separation technology. In contrast, the membrane separation technology has the characteristics of low energy consumption, high-efficiency separation, no secondary pollution and simple operation, and has great application value in radioactive wastewater treatment.

At present, the ultrafiltration technology is used together with other treatment technologies, and is most widely used in the research and application of radioactive wastewater treatment, but the ultrafiltration membrane is very difficult in radioactive wastewater treatment due to the low hydrophilic and adaptive properties of PVDF, PTFE and the like which are materials for preparing the ultrafiltration membrane. In order to solve the series of technical problems, research on ultrafiltration membranes has never been stopped. The MOF material has the advantages of high specific surface area and high stability, and is used for preparing the ultrafiltration membrane. The Chinese patent document CN108854569A discloses a preparation method of a metal organic framework material MOF loaded ZnO scale inhibition ultrafiltration membrane, metal salt and ligand are used as raw materials, MOF is prepared under the hydrothermal reaction condition, the obtained MOF material is loaded with ZnO and then mixed for membrane preparation, the hydrophilicity of the MOF material ultrafiltration membrane prepared by the technical patent is improved, the pure water flux is improved to a certain extent, and the retention rate is also improved. However, although the membrane hydrophilicity is improved to a certain extent and the filtering performance is improved, the membrane has weak adaptability under the condition of limiting the conditions of pH, ion concentration and the like in radioactive wastewater, the removal rate of the whole radioactive ions is low, and no related document discloses that the iron-based MOF material is used for preparing the ultrafiltration membrane for removing nuclide cerium in the radioactive wastewater.

Disclosure of Invention

The invention solves the technical problem that the radioactive wastewater in the prior art has the defect of low cerium interception rate of an ultrafiltration membrane due to less complexing sites under the conditions of pH value, ion concentration and the like, and provides an iron-based MOF material modified ultrafiltration membrane, a preparation method and application thereof. The iron-based MOF material modified ultrafiltration membrane has excellent flux, pH responsiveness and pollution resistance.

The invention solves the technical problems by the following technical proposal:

the invention provides a preparation method of an iron-based MOF material modified ultrafiltration membrane, which comprises the following steps:

s1, under the condition that a solvent exists, ferric salt and 2-amino terephthalic acid are subjected to crystallization reaction to prepare an iron-based MOF material; wherein the mass ratio of the 2-amino terephthalic acid to the ferric salt is 3 (3-13);

s2, sequentially adding an acrylic monomer and a PVDF film into the mixture containing the iron-based MOF material, and carrying out ultrasonic mixing and irradiation reaction to obtain the iron-based MOF material modified ultrafiltration membrane.

In the present invention, those skilled in the art will generally understand that the iron-based MOF material is described as Fe ³⁺ And a crystalline porous material having a periodic network structure formed by self-assembly with the organic ligand.

In step S1, the mass of the 2-amino terephthalic acid and the iron salt is preferably 3: (7-13), for example, 3:9.

in step S1, the iron salt may be ferric chloride, ferric nitrate or ferric sulfate.

In step S1, the solvent may be a solvent conventional in the art, for example, N-dimethylformamide.

In step S1, the mass ratio of the solvent to the "total amount of the iron salt and 2-amino terephthalic acid" may be (15.5 to 43.5): 1, preferably (15.5 to 25.6): 1, for example 21.3:1 or 18.1:1, when the mass ratio of the solvent to the total amount of the ferric salt and the 2-amino terephthalic acid is (15.5-43.5): 1, the yield of the prepared iron-based MOF material is higher.

In step S1, the solvent, the ferric salt and the 2-amino terephthalic acid are generally stirred and mixed to prepare a mixture before the crystallization reaction.

Wherein, the stirring and mixing time can be conventional in the field, and the stirring and mixing time is generally uniform. For example, the stirring and mixing time may be 10 minutes.

In step S1, the crystallization reaction can be carried out by a conventional method in the art, and the mixture of the solvent, the ferric salt and the 2-amino terephthalic acid is generally put into a reaction kettle and put into an oven for reaction.

In step S1, the crystallization reaction time may be 18 to 30 hours, preferably 22 to 26 hours, for example 24 hours.

In step S1, the crystallization reaction may be performed at a temperature of 100 to 150 ℃, for example, 120 ℃.

In step S1, the crystallization reaction may further include cooling, centrifuging, washing and drying.

Wherein the washing may be performed using N, N-dimethylformamide and/or ethanol, preferably, the washing is performed three times using N, N-dimethylformamide and then three times using ethanol.

Wherein the drying may be vacuum drying.

Wherein the temperature of the drying may be 55-70 ℃, for example 60 ℃.

In step S2, the preparation method of the mixture containing the iron-based MOF material may be conventional in the art, and preferably includes the following steps: and (3) carrying out ultrasonic mixing on the iron-based MOF material and a solvent, and standing.

Wherein the solvent may be a solvent conventional in the art, such as water.

Wherein the volume ratio of the iron-based MOF material to the solvent may be 2:1.

Wherein, the time of ultrasonic mixing may be 30min.

Wherein the time of the standing can be 10-14 hours, for example 12 hours. The purpose of standing is to defoam.

In step S2, the mass ratio of the iron-based MOF material and the acrylic monomer is preferably 1:15.

In step S2, the acrylic monomer may be acrylic acid or methacrylic acid, preferably methacrylic acid.

In step S2, the PVDF film may be used in an amount of 17 to 19%, for example, 17%, by weight of the PVDF film to the iron-based MOF material. When the dosage of the PVDF membrane is 17%, the yield of the prepared iron-based MOF material modified ultrafiltration membrane is higher.

In step S2, the PVDF film may be prepared by a conventional method in the art, and preferably, the preparation method of the PVDF film includes the steps of: and (3) standing the casting solution containing PVDF, a pore-forming agent and an organic solvent, defoaming, and separating phases to obtain the PVDF-pore-forming agent.

Wherein the porogen may be a porogen conventional in the art, preferably polyvinylpyrrolidone PVPK30.

Wherein the organic solvent may be a solvent conventional in the art, preferably a nonpolar solvent, more preferably one or more of N-methylpyrrolidone NMP, dimethylacetamide DMAc, dimethylformamide DMF, dimethylsulfoxide DMSO and triethylphosphate TEP, for example NMP.

Wherein the porogen may be used in an amount conventional in the art, preferably 20-26%, for example 23.5%, by weight of the porogen to the PVDF.

The solids content of the casting solution may be conventional in the art, and is preferably 18 to 25%, for example 21%. Wherein the solid content refers to the mass sum of the PVDF and the pore-foaming agent and accounts for the mass percentage of the casting solution.

In one embodiment of the invention, the PVDF film is prepared by the following method: stirring a mixed material containing PVDF and PVPK30 in a solvent to form a homogeneous and stable casting solution, standing and defoaming, and preparing a PVDF film by adopting a non-solvent induced phase separation method;

wherein the solvent is NMP;

wherein the mass volume ratio of PVDF, PVPK30 and NMP is 17g:4g:79mL.

The non-solvent induced phase separation method can be carried out according to a conventional method in the art, generally an extracting agent with stronger intersolubility with the organic solvent is added into the defoamed casting film liquid, the organic solvent is extracted, a two-phase structure with the PVDF as a continuous phase and the organic solvent as a disperse phase is formed, and then the organic solvent is removed, so that the PVDF film with a certain pore structure is obtained.

In step S2, the operation of ultrasonic mixing preferably includes the steps of: adding the acrylic monomer into the mixture containing the iron-based MOF material, then ultrasonically mixing for 3-8 min, such as 5min, adding the solvent, ultrasonically mixing for 3-8 min, such as 5min, and adding the PVDF film, and ultrasonically mixing for 8-12 min, such as 10min.

Wherein the solvent is preferably added in an amount of 5 mL/l to the volume mass of the iron-based MOF material: 1mg.

In step S2, when the feeding sequence in the ultrasonic mixing process is the mixture of the iron-based MOF material, the acrylic monomer and the PVDF film in sequence, the yield of the prepared modified ultrafiltration membrane of the iron-based MOF material is higher.

In step S2, the irradiation may be ultraviolet light irradiation. The purpose of the irradiation is a grafting reaction. When irradiated with ultraviolet light, the ultraviolet light intensity is preferably not less than 500 w.h/m ² 。

In step S2, the irradiation time may be 0 to 8 hours, for example 8 hours.

In step S2, the post-irradiation treatment may further include suction filtration.

The invention also provides an iron-based MOF material modified ultrafiltration membrane, which is prepared by adopting the preparation method of the iron-based MOF material modified ultrafiltration membrane.

The invention also provides application of the iron-based MOF material modified ultrafiltration membrane in wastewater treatment.

In the invention, what isThe waste water may be radioactive waste water, e.g. containing ¹⁴¹ Ce and/or ¹⁴⁴ Radioactive wastewater of Ce.

Wherein the said contains ¹⁴¹ Ce and/or ¹⁴⁴ In radioactive wastewater of Ce, the Ce ³⁺ The concentration of (C) may be 1 to 10mg/L, for example 5mg/L.

On the basis of conforming to the common knowledge in the field, the above preferred conditions can be arbitrarily combined to obtain the preferred examples of the invention.

The reagents and materials used in the present invention are commercially available.

The invention has the positive progress effects that: the iron-based MOF material modified ultrafiltration membrane has excellent flux, pH responsiveness and pollution resistance, and can effectively intercept Ce ³⁺ Solves the problem that the ultrafiltration membrane is less in complexing sites to Ce under the condition of limiting the pH value, the ion concentration and the like of radioactive wastewater ³⁺ The problem of reduced retention rate is that the radioactive wastewater treatment shows good filtration performance.

Drawings

FIG. 1 is a graph showing the relationship between the contact angle of the iron-based MOF material modified ultrafiltration membrane prepared in examples 1 to 6 and the contact angle of the unmodified PVDF membrane prepared in comparative example 1 with time.

FIG. 2 shows the Ce-concentration of the iron-based MOF material modified ultrafiltration membrane prepared in examples 1 to 6 and the unmodified PVDF membrane prepared in comparative example 1 at different pH values ³⁺ Is a high retention rate.

FIG. 3 is a graph showing the flux versus operating time of the iron-based MOF material modified ultrafiltration membranes prepared in examples 1 to 6 and the unmodified PVDF membrane prepared in comparative example 1.

FIG. 4 is a graph showing the flux attenuation of the iron-based MOF material modified ultrafiltration membrane prepared in example 4 and the unmodified PVDF membrane prepared in comparative example 1 in a contamination and backwash experiment.

Detailed Description

The invention is further illustrated by means of the following examples, which are not intended to limit the scope of the invention. The experimental methods, in which specific conditions are not noted in the following examples, were selected according to conventional methods and conditions, or according to the commercial specifications.

In examples 1 to 6, iron chloride, N-dimethylformamide, 2-aminoterephthalic acid, methacrylic acid (MAA) were purchased from China medical group.

Polyvinylidene fluoride (PVDF) was purchased from sorv group company under model 6020.

The PVDF membranes used in examples 1 to 6 were subjected to the following pretreatment processes: the PVDF membrane was washed with deionized water and soaked in deionized water for more than one week, changed water multiple times during which time it was dried to constant weight under vacuum at 70 ℃.

The PVDF films used in examples 1 to 6 were prepared by the following methods: 17g PVDF and 4g PVPK30 are dissolved in 79mL organic solvent NMP, and the mixture is magnetically stirred to form homogeneous and stable casting solution, and the casting solution is prepared by adopting a non-solvent induced phase separation method after standing and defoaming treatment.

Example 1

S1, adding 0.225g of 2-amino terephthalic acid and 0.225g of ferric chloride into 19.55mL of N, N-dimethylformamide solution, stirring for 10min, transferring into a reaction kettle, and crystallizing in an oven at 120 ℃ for 24h. After cooling to room temperature and centrifugal separation, the obtained product is washed three times by an N, N-dimethylformamide solution and an ethanol solution respectively, and the iron-based MOF material is obtained after vacuum drying at 60 ℃;

s2, putting 20mg of the iron-based MOF material into 10mL of water for 30min ultrasonic treatment, standing for 12h, adding 300mg of MAA for continuous ultrasonic treatment for 5min, and adding 100mL of water for ultrasonic treatment for 5min again. Adding 17% of PVDF film, continuing to carry out ultrasonic treatment for 10min, wherein the percentage is the percentage of the PVDF film to the mass of the iron-based MOF material, and carrying out suction filtration after ultraviolet irradiation for 8h to obtain the iron-based MOF material modified ultrafiltration film.

Example 2

The amount of ferric chloride in step (1) was 0.375g and the amount of N, N-dimethylformamide was 19.4mL; 19% of PVDF film is added in the step (2), and the other materials are the same as in the example 1, so as to obtain the iron-based MOF material modified ultrafiltration film.

Example 3

The amount of ferric chloride in the step (1) was 0.525g, the amount of N, N-dimethylformamide was 19.25mL, and the same as in example 1 was used to obtain an iron-based MOF material-modified ultrafiltration membrane.

Example 4

The amount of ferric chloride in the step (1) was 0.8235 g, the amount of N, N-dimethylformamide was 19.1mL, and the same as in example 1 was used to obtain an iron-based MOF material-modified ultrafiltration membrane.

Example 5

The amount of ferric chloride in the step (1) was 0.675g, the amount of N, N-dimethylformamide was 19.1mL, and the same as in example 1 was repeated to obtain an iron-based MOF material-modified ultrafiltration membrane.

Example 6

The amount of ferric chloride in the step (1) was 0.975g, and the amount of N, N-dimethylformamide was 18.8mL, except that the same as in example 1 was used, to obtain an iron-based MOF material-modified ultrafiltration membrane.

Comparative example 1

17g PVDF and 4g PVPK30 are dissolved in 79mL of organic solvent NMP, and are magnetically stirred to form homogeneous and stable casting solution, and after standing and defoaming treatment, a non-solvent induced phase separation method is adopted to prepare the PVDF film.

Effect example 1

The iron-based MOF material-modified ultrafiltration membranes prepared in examples 1 to 6 and the unmodified PVDF membrane prepared in comparative example 1 were subjected to contact angle measurement with a contact angle meter at 1. Mu.L of water drops, and the results are shown in Table 1 and FIG. 1.

TABLE 1 contact angle of iron-based MOF material modified Ultrafiltration films prepared in examples 1 to 6 and unmodified PVDF film prepared in comparative example 1 changes with time

As can be seen from fig. 1 and table 1, the hydrophilicity of the iron-based MOF material modified ultrafiltration membranes prepared in examples 1 to 6 is effectively improved compared to the unmodified PVDF membrane prepared in comparative example 1, which provides a guarantee for the radioactive wastewater treatment.

Effect example 2

At Ce ³⁺ Membrane filtration experiments were carried out at an initial concentration of 5mg/L and a transmembrane pressure tmp=0.2 MPa to investigate wastewaterAt pH of 2-7, the iron-based MOF material modified ultrafiltration membranes prepared in examples 1-6 and the unmodified PVDF membrane prepared in comparative example 1 were used for preparing Ce ³⁺ Retention, results are shown in table 2 and figure 2, where Ce ³⁺ The retention rate was calculated using the following formula:

TABLE 2 iron-based MOF Material modified Ultrafiltration films prepared in examples 1 to 6 and unmodified PVDF film prepared in comparative example 1 were subjected to Ce at different pH values ³⁺ Is of the retention rate of (2)

As can be seen from fig. 2 and table 2, the iron-based MOF material modified ultrafiltration membranes prepared in examples 1 to 6 exhibited excellent rejection capacities, as compared to the unmodified PVDF membrane prepared in comparative example 1, wherein the iron-based MOF material modified ultrafiltration membrane prepared in example 4 exhibited optimal removal effects. When the pH is less than 4, the iron-based MOF material modified ultrafiltration membrane prepared in examples 1 to 6 has the following structure that the pH is less than 4 ³⁺ The retention rate of (2) is 90.5% or less because the wastewater contains a large amount of H ⁺ ，H ⁺ Will be combined with Ce ³⁺ Competing with each other for complexing sites on the complexing agent, resulting in Ce ³⁺ Complexing reaction with complexing agent is difficult to occur, so the iron-based MOF material modified ultrafiltration membrane is resistant to Ce ³⁺ The rejection rate of (2) is low. When the pH is more than 4, the iron-based MOF material modified ultrafiltration membrane prepared in examples 1 to 6 has the same pH as that of wastewater ³⁺ The retention rate of the metal ion-exchange membrane is continuously improved, which proves that the iron-based MOF material modified ultrafiltration membrane has the properties of efficient filtration separation and pH response.

Effect example 3

At Ce ³⁺ Strip with a concentration of 5mg/l, ph=4, transmembrane pressure tmp=0.2 MPaUnder the conditions, the purified water yield was monitored, and the flux (the net water yield per unit time per unit membrane area) of the iron-based MOF material modified ultrafiltration membranes prepared in examples 1 to 6 and the unmodified PVDF membrane prepared in comparative example 1 was measured as a function of the running time, and the results are shown in Table 3 and FIG. 3, wherein the flux was calculated using the following formula:

wherein F is flux in units of/L/(m) ² h) Q is the permeation quantity of liquid, and the unit is m ³ A is the area of the film, the unit is m ² T is the time for collecting the liquid in h.

TABLE 3 flux and run time variation of the iron-based MOF material modified Ultrafiltration membranes prepared in examples 1 to 6 and the unmodified PVDF membrane prepared in comparative example 1

As can be seen from Table 3 and FIG. 3, the flux of the unmodified PVDF membrane prepared in comparative example 1 is obviously reduced after 400min of operation, while the flux of the iron-based MOF material modified ultrafiltration membranes prepared in examples 1 to 6 is not obviously reduced even if the membrane is operated for 800min, because the iron-based MOF material in the iron-based MOF material modified ultrafiltration membrane contains metal elements, has stronger polarity in microscopic pore canals, can generate strong force with adsorbed substances, and continuously applies complexing agent and Ce ³⁺ The generated complex is blocked outside the membrane, and water molecules can continuously permeate the membrane holes, so that the purified water yield is obviously increased.

Effect example 4

The iron-based MOF material modified ultrafiltration membrane prepared in example 4 and the unmodified PVDF membrane prepared in comparative example 1 were subjected to pollution and backwashing experiments, and testedFlux attenuation condition, pollution experiment is that the membrane is at Ce ³⁺ In wastewater with a concentration of 5mg/l and a pH=4, the wastewater is operated for 200min under the condition of transmembrane pressure TMP=0.2 MPa, and the cleaning experiment is that the membrane is operated for 200min under the condition of transmembrane pressure TMP=0.2 MPa in clean water. The flux of the membrane after contamination and after cleaning was recorded, and the flux decay rate of the membrane was calculated, and specific results are shown in table 4 and fig. 4, wherein the flux decay rate was calculated using the following formula:

TABLE 4 flux attenuation conditions of pollution and backwash experiments with the iron-based MOF material modified ultrafiltration membrane prepared in example 4 and the unmodified PVDF membrane prepared in comparative example 1

The results show that the Ce-containing material was present over 1400min ³⁺ After radioactive wastewater pollution and clean water washing, the flux of the unmodified PVDF membrane prepared in comparative example 1 was reduced to 25% of the original flux, even after washing, the flux was recovered to only 39% of the original flux at 1600min, while the Ce-containing ultrafiltration membrane prepared in example 4 was obtained after 1400min ³⁺ After the radioactive wastewater is polluted and cleaned by clean water, the flux of the radioactive wastewater is 31% of the original flux, but after the radioactive wastewater is cleaned again, the flux of the radioactive wastewater is recovered to 95% of the original flux at 1600min, and the radioactive wastewater shows excellent anti-pollution performance.

The above embodiments are preferred embodiments of the invention, but the embodiments of the invention are not limited by the above embodiments, and any other modifications, substitutions, and combinations are equivalent without departing from the spirit and principles of the invention.

Claims

1. The preparation method of the iron-based MOF material modified ultrafiltration membrane is characterized by comprising the following steps of:

2. The method for preparing an iron-based MOF material modified ultrafiltration membrane according to claim 1, wherein in step S1, the mass ratio of the 2-amino terephthalic acid to the iron salt is 3: (7-13), for example, 3:9, a step of performing the process;

and/or the ferric salt is ferric chloride, ferric nitrate or ferric sulfate;

and/or the solvent is N, N-dimethylformamide;

and/or the mass ratio of the solvent to the total amount of the iron salt and 2-amino terephthalic acid is (15.5-43.5): 1, preferably (15.5 to 25.6): 1, for example 21.3:1 or 18.1:1.

3. the method for preparing an iron-based MOF material modified ultrafiltration membrane according to claim 1, wherein in step S1, the crystallization reaction time is 18-30 hours, preferably 22-26 hours, such as 24 hours;

and/or the crystallization reaction is carried out at a temperature of 100-150 ℃, for example 120 ℃.

4. The method for preparing the modified ultrafiltration membrane of the iron-based MOF material as claimed in claim 1, wherein the crystallization reaction further comprises cooling, centrifuging, washing and drying;

wherein the washing is preferably washing with N, N-dimethylformamide and/or ethanol, more preferably washing with N, N-dimethylformamide three times before washing with ethanol three times;

wherein the drying is preferably vacuum drying;

wherein the drying temperature is preferably 55-70 ℃, e.g. 60 ℃.

5. The method for preparing the modified ultrafiltration membrane of the iron-based MOF material as claimed in claim 1, wherein in the step S2, the preparation method of the mixture containing the iron-based MOF material comprises the following steps: ultrasonically mixing the iron-based MOF material with a solvent, and standing;

in the process for preparing a mixture containing the iron-based MOF material, the solvent is preferably water;

in the preparation method of the mixture containing the iron-based MOF material, the volume ratio of the iron-based MOF material to the solvent is preferably 2:1;

in the method for preparing the mixture containing the iron-based MOF material, the ultrasonic mixing time is preferably 30min;

in the method for preparing a mixture containing the iron-based MOF material, the time for the standing is preferably 10 to 14 hours, for example, 12 hours.

6. The method for preparing an iron-based MOF material modified ultrafiltration membrane according to claim 1, wherein in step S2, the mass ratio of the iron-based MOF material to the acrylic monomer is 1:15;

and/or the acrylic monomer is acrylic acid or methacrylic acid, preferably methacrylic acid;

and/or the dosage of the PVDF film is 17-19%, and the percentage is the mass percentage of the PVDF film in the iron-based MOF material;

and/or, the preparation method of the PVDF film comprises the following steps: the casting solution containing PVDF, a pore-forming agent and an organic solvent is obtained through standing, defoaming treatment and phase separation;

wherein the porogen is preferably polyvinylpyrrolidone PVPK30;

wherein the organic solvent is preferably one or more of N-methylpyrrolidone NMP, dimethylacetamide DMAc, dimethylformamide DMF, dimethyl sulfoxide DMSO and triethyl phosphate TEP, for example NMP;

wherein the amount of the pore-forming agent is preferably 20-26%, for example 23.5%, and the percentage is the mass percentage of the pore-forming agent in the PVDF;

the solid content in the casting solution is preferably 18 to 25%, for example, 21%.

7. The method for preparing an iron-based MOF material modified ultrafiltration membrane according to claim 1, wherein in step S2, the operation of ultrasonic mixing comprises the steps of: adding the acrylic monomer into the mixture containing the iron-based MOF material, then carrying out ultrasonic mixing for 3-8 min, such as 5min, adding the solvent, carrying out ultrasonic mixing for 3-8 min, such as 5min, and adding the PVDF film, carrying out ultrasonic mixing for 8-12 min, such as 10min;

wherein, the addition amount of the solvent and the volume mass of the iron-based MOF material are preferably 5mL:1mg.

8. The method for preparing an iron-based MOF material modified ultrafiltration membrane according to claim 1, wherein in step S2, the irradiation is ultraviolet light irradiation;

wherein the ultraviolet light intensity of the ultraviolet light irradiation is preferably not less than 500 w.h/m ² ；

And/or the irradiation time is 0 to 8 hours, for example 8 hours;

and/or, the irradiation further comprises suction filtration.

9. An iron-based MOF material modified ultrafiltration membrane prepared by the method for preparing the iron-based MOF material modified ultrafiltration membrane according to any one of claims 1 to 8.

10. Use of an iron-based MOF material modified ultrafiltration membrane according to claim 9 in the treatment of wastewater, preferably containing ¹⁴¹ Ce and/or ¹⁴⁴ Radioactive wastewater of Ce.