A zirconium-based metal organic framework-polydimethylsiloxane composite film and its preparation method and application

Abstract

The present invention provides a zirconium-based metal organic framework-polydimethylsiloxane composite membrane and a preparation method and application thereof, and relates to the field of membrane separation technology. The present invention uses Zr-MOF to modify the PDMS membrane. The introduction of Zr-MOF not only enhances the ion selectivity and transmission rate of the membrane, but also improves the environmental adaptability and overall separation performance of the membrane due to its porosity and adjustable chemical functionality. The present invention combines the porosity, high specific surface area and chemical stability of the UiO-66 series MOFs with the flexibility and chemical corrosion resistance of PDMS to obtain a monovalent and divalent cation separation membrane with high performance, and improves the water swelling resistance of the PDMS membrane. In addition, the high specific surface area of ​​Zr-MOF helps to improve the anti-pollution ability of the membrane, while its chemical stability helps to maintain the performance of the membrane under harsh conditions.

Description

Technical Field

[0001] The present invention relates to the field of membrane separation technology, and in particular to a zirconium-based metal organic framework-polydimethylsiloxane composite membrane and a preparation method and application thereof. Background Art

[0002] The separation of monovalent and divalent cations refers to the separation of monovalent cations (such as Na + , K + ) and divalent cations (such as Ca 2+ Mg 2+ ) is a technology that can efficiently distinguish and separate substances. This separation is critical for a variety of applications, including desalination, industrial wastewater treatment, pharmaceutical purification, and resource recovery.

[0003] At present, polydimethylsiloxane (PDMS) membranes are commonly used for the separation of monovalent and divalent cations. Although PDMS membranes show good flexibility and chemical corrosion resistance in the separation of monovalent and divalent cations, they also have problems such as limited ion selectivity and easy water swelling. Summary of the invention

[0004] The purpose of the present invention is to provide a zirconium-based metal organic framework-polydimethylsiloxane composite membrane and its preparation method and application. The composite membrane provided by the present invention can efficiently separate monovalent and divalent cations and has good ion selectivity and water swelling resistance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a zirconium-based metal organic framework-polydimethylsiloxane composite film, comprising a polydimethylsiloxane-based base film and a zirconium-based metal organic framework material dispersed in the polydimethylsiloxane-based base film;

[0007] The zirconium-based metal organic framework material includes UiO-66, UiO-66-NH2 or UiO-66-NO2;

[0008] The mass of the zirconium-based metal organic framework material is 2.5-10% of the mass of the polydimethylsiloxane-based base film.

[0009] Preferably, the preparation method of UiO-66-NH2 or UiO-66-NO2 comprises the following steps:

[0010] The zirconium source and the organic ligand are mixed and ground to obtain a mixed powder; when the target product is UiO-66-NH2, the organic ligand is 2-aminoterephthalic acid; when the target product is UiO-66-NO2, the organic ligand is 2-nitroterephthalic acid;

[0011] The mixed powder is subjected to coordination reaction in an autoclave to obtain the UiO-66-NH2 or UiO-66-NO2; the temperature of the coordination reaction is 100-150°C.

[0012] Preferably, the molar ratio of Zr to the organic ligand in the zirconium source is 1:1.

[0013] Preferably, the coordination reaction time is 10 to 24 hours.

[0014] The present invention provides a method for preparing the zirconium-based metal organic framework-polydimethylsiloxane composite film described in the above scheme, comprising the following steps:

[0015] dissolving polydimethylsiloxane in a first organic solvent to obtain a solution;

[0016] dispersing the zirconium-based metal organic framework material in a second organic solvent to obtain a dispersion;

[0017] The dispersion liquid is mixed with the dissolving liquid to obtain a casting liquid; the mass of the zirconium-based metal organic framework material in the casting liquid is 2.5 to 10% of the mass of the polydimethylsiloxane;

[0018] The casting solution is subjected to film forming to obtain the zirconium-based metal organic framework-polydimethylsiloxane composite film.

[0019] Preferably, the first organic solvent and the second organic solvent are independently heptane or hexane.

[0020] Preferably, the film forming comprises: spreading the casting solution onto a substrate, allowing it to stand, and subjecting it to vacuum treatment to form a zirconium-based metal organic framework-polydimethylsiloxane composite film on the substrate.

[0021] Preferably, the mass ratio of the polydimethylsiloxane solvent to the first organic solvent is 1-5:1; and the concentration of the zirconium-based metal organic framework material in the dispersion is 0.05-0.1 g / mL.

[0022] The present invention provides the use of the zirconium-based metal organic framework-polydimethylsiloxane composite membrane described in the above scheme or the zirconium-based metal organic framework-polydimethylsiloxane composite membrane prepared by the preparation method described in the above scheme as a separation membrane in separating monovalent and divalent cations.

[0023] Preferably, the monovalent cation includes Na + and / or K + , divalent cations include Ca 2+ .

[0024] The present invention provides a zirconium-based metal organic framework-polydimethylsiloxane composite film, comprising a polydimethylsiloxane-based base film and a zirconium-based metal organic framework material dispersed in the polydimethylsiloxane-based base film; the zirconium-based metal organic framework material comprises UiO-66, UiO-66-NH2 or UiO-66-NO2; the mass of the zirconium-based metal organic framework material is 2.5-10% of the mass of the polydimethylsiloxane-based base film.

[0025] The present invention modifies the PDMS membrane by using a zirconium-based metal organic framework material (Zr-MOF). The introduction of Zr-MOF not only enhances the ion selectivity and transmission rate of the membrane, but also improves the environmental adaptability and overall separation performance of the membrane due to its porosity and adjustable chemical functionality.

[0026] The present invention combines the porosity, high specific surface area and chemical stability of the UiO-66 series MOFs with the flexibility and chemical corrosion resistance of PDMS to obtain a high-performance monovalent and divalent cation separation membrane, thereby improving the water swelling resistance of the PDMS membrane.

[0027] In addition, the high specific surface area of ​​Zr-MOF helps to improve the membrane's anti-fouling ability, while its chemical stability helps to maintain the membrane's performance under harsh conditions. Therefore, Zr-MOF-modified PDMS membranes show significant potential in achieving efficient and stable separation of monovalent and divalent cations.

[0028] The present invention provides a method for preparing a zirconium-based metal organic framework-polydimethylsiloxane composite membrane. The preparation process is simple and easy to mass produce. The prepared composite membrane has broad application prospects in the fields of seawater desalination, wastewater treatment and resource recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the preparation process of the zirconium-based metal organic framework-polydimethylsiloxane composite film of the present invention;

[0030] Figure 2 XRD patterns of different Zr-MOF@PDMS films (a) and XRD patterns of different Zr-MOFs (b);

[0031] Figure 3 Current-voltage (IV) curves of three Zr-MOFs-0.05@PDMS membranes prepared in Examples 1, 3 and 5 and the PDMS membrane prepared in Comparative Example 1;

[0032] Figure 4 The three Zr-MOFs-0.05@PDMS membranes prepared in Examples 1, 3 and 5 were prepared in the presence of 1 mol·L -1 NaCl and 1 mol·L -1X-ray diffraction (XRD) pattern after immersion in CaCl2 salt solution for 10 days. DETAILED DESCRIPTION

[0033] The present invention provides a zirconium-based metal organic framework-polydimethylsiloxane composite film, comprising a polydimethylsiloxane-based base film and a zirconium-based metal organic framework material dispersed in the polydimethylsiloxane-based base film;

[0034] The zirconium-based metal organic framework material includes UiO-66, UiO-66-NH2 or UiO-66-NO2;

[0035] The mass of the zirconium-based metal organic framework material is 2.5-10% of the mass of the polydimethylsiloxane-based base film, preferably 3-8%, and more preferably 4-6%.

[0036] In the present invention, the UiO-66-NH2 is formed by linking zirconium nodes with an organic skeleton of 2-aminoterephthalic acid; and the UiO-66-NO2 is formed by linking zirconium nodes with an organic skeleton of 2-nitroterephthalic acid.

[0037] In the present invention, the particle size of the zirconium-based metal organic framework material is preferably 40 to 200 nm, more preferably 60 to 180 nm, and further preferably 100 to 150 nm.

[0038] In the present invention, the zirconium-based metal organic framework material is preferably obtained by self-production; wherein the preparation method of UiO-66 preferably comprises the following steps:

[0039] The zirconium source and terephthalic acid are mixed and ground to obtain a mixed powder;

[0040] The mixed powder is subjected to coordination reaction in an autoclave to obtain the UiO-66.

[0041] In the present invention, the zirconium source preferably includes ZrOCl2·8H2O, Zr(On-Bu)4 (anhydrous zirconium tetrabutoxide) or Zr(acac)4 (zirconium acetylacetonate); the molar ratio of Zr to terephthalic acid in the zirconium source is preferably 1:1.

[0042] In the present invention, the mixing and grinding is preferably carried out at room temperature; the mixing and grinding time is preferably 5 to 15 minutes. The present invention ensures that the zirconium source and the organic ligand (terephthalic acid) are fully mixed through mixing and grinding, increases the contact area, and forms a uniform precursor solid mixture, which is conducive to the formation and growth of crystals during the synthesis process.

[0043] In the present invention, the temperature of the coordination reaction is preferably 100 to 150° C., more preferably 120 to 130° C.; the time of the coordination reaction is preferably 10 to 24 hours, more preferably 12 to 20 hours.

[0044] After the coordination reaction is completed, the present invention preferably cools the autoclave to room temperature, washes the obtained white solid with 60-80° C. ethanol for 0.5-4 h, and finally dries it under vacuum at 150° C. for 12 h to obtain the UiO-66.

[0045] Compared with the conventional solvothermal method for preparing UiO-66, which requires a large amount of N,N-dimethylformamide (DMF), which is toxic and harmful, the preparation method of the present invention is a solvent-free method and is green and environmentally friendly.

[0046] In the present invention, the preparation method of UiO-66-NH2 is the same as the preparation method of UiO-66, the only difference being that the organic ligand terephthalic acid is replaced by 2-aminoterephthalic acid.

[0047] In the present invention, the preparation method of UiO-66-NO2 is the same as the preparation method of UiO-66, the only difference being that the organic ligand terephthalic acid is replaced by 2-nitroterephthalic acid.

[0048] The present invention chemically modifies UiO-66 and introduces different functional groups (-NO2, -NH2), which can further regulate the surface properties and ion selectivity of the composite membrane and improve the separation efficiency and performance stability of the membrane.

[0049] In the present invention, the thickness of the zirconium-based metal organic framework-polydimethylsiloxane composite film is preferably 500-800 μm, more preferably 600-700 μm. In the embodiment of the present invention, specifically 600±0.01 μm.

[0050] The present invention modifies the PDMS membrane by using a zirconium-based metal organic framework material (Zr-MOF). The introduction of Zr-MOF not only enhances the ion selectivity and transmission rate of the membrane, but also improves the environmental adaptability and overall separation performance of the membrane due to its porosity and adjustable chemical functionality.

[0051] The present invention combines the porosity, high specific surface area and chemical stability of the UiO-66 series MOFs with the flexibility and chemical corrosion resistance of PDMS to obtain a high-performance monovalent and divalent cation separation membrane, thereby improving the water swelling resistance of the PDMS membrane.

[0052] The present invention provides a method for preparing the zirconium-based metal organic framework-polydimethylsiloxane composite film described in the above scheme, such as Figure 1 As shown, the following steps are included:

[0053] dissolving polydimethylsiloxane in a first organic solvent to obtain a solution;

[0054] dispersing the zirconium-based metal organic framework material in a second organic solvent to obtain a dispersion;

[0055] The dispersion liquid is mixed with the dissolving liquid to obtain a casting liquid; the mass of the zirconium-based metal organic framework material in the casting liquid is 2.5 to 10% of the mass of the polydimethylsiloxane;

[0056] The casting solution is subjected to film forming to obtain the zirconium-based metal organic framework-polydimethylsiloxane composite film.

[0057] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0058] The present invention dissolves polydimethylsiloxane in a first organic solvent to obtain a dissolving solution.

[0059] In the present invention, the first organic solvent preferably includes heptane or hexane; the mass ratio of the polydimethylsiloxane to the first organic solvent is preferably 1 to 5:1, specifically 1:1, 2:1, 3:1, 4:1 or 5:1.

[0060] The present invention disperses the zirconium-based metal organic framework material into a second organic solvent to obtain a dispersion.

[0061] In the present invention, the second organic solvent preferably includes heptane or hexane; the concentration of the zirconium-based metal organic framework material in the dispersion is preferably 0.05-0.1 g / mL. In the present invention, the dispersion is preferably carried out under ultrasonic conditions, and the present invention has no special requirements for the ultrasonic conditions, as long as the zirconium-based metal organic framework material can be evenly dispersed.

[0062] After obtaining the dissolving solution and the dispersion solution, the present invention mixes the dispersion solution with the dissolving solution to obtain a casting solution.

[0063] In the present invention, the dispersion is preferably added to the dissolving liquid for mixing. In the present invention, the mixing is preferably performed under stirring conditions. The present invention has no special requirements for the stirring conditions, as long as the dissolving liquid and the dispersion can be mixed uniformly.

[0064] After obtaining the casting solution, the present invention forms a film on the casting solution to obtain the zirconium-based metal organic framework-polydimethylsiloxane composite film.

[0065] In the present invention, the film forming preferably includes: spreading the casting solution onto a substrate, allowing it to stand, and vacuum treating it to form a zirconium-based metal organic framework-polydimethylsiloxane composite film on the substrate.

[0066] The present invention has no special requirements for the substrate, and any substrate that can form a film known in the art can be used. In the embodiment of the present invention, a 5.5×5.5 cm culture dish is specifically used as the substrate. The present invention has no special requirements for the tiling process, and in the embodiment of the present invention, the casting liquid is specifically poured evenly into the culture dish.

[0067] In the present invention, the standing time is preferably 100° C. and the time is preferably 2 hours. The present invention promotes the volatilization of the organic solvent without causing thermal decomposition of PDMS or Zr-MOF.

[0068] The present invention has no special requirements for the vacuum treatment conditions, and the vacuum treatment conditions known in the art can be used. In the embodiment of the present invention, the vacuum treatment is 5 minutes. The present invention further removes bubbles and unvolatile solvents in the film through vacuum treatment, thereby improving the uniformity and density of the film.

[0069] After the film is formed, the present invention peels the film off the substrate to obtain a zirconium-based metal organic framework-polydimethylsiloxane composite film.

[0070] The present invention provides the use of the zirconium-based metal organic framework-polydimethylsiloxane composite membrane described in the above scheme or the zirconium-based metal organic framework-polydimethylsiloxane composite membrane prepared by the preparation method described in the above scheme as a separation membrane in separating monovalent and divalent cations.

[0071] In the present invention, the monovalent cation preferably includes Na + and / or K + , divalent cations preferably include Ca 2+ .

[0072] The present invention combines the porosity, high specific surface area and chemical stability of the UiO-66 series MOFs with the flexibility and chemical corrosion resistance of PDMS to obtain a high-performance monovalent and divalent cation separation membrane that can efficiently separate monovalent and divalent cations and has good ion selectivity and resistance to water swelling.

[0073] The zirconium-based metal organic framework-polydimethylsiloxane composite film provided by the present invention and its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0074] The preparation method of the zirconium-based metal organic framework (Zr-MOF) used in the following examples is as follows:

[0075] Preparation of UiO-66

[0076] ZrOCl2·8H2O (1.5 mmol) was used as a metal precursor and mixed with terephthalic acid (1.5 mmol) and ground at room temperature for 10 minutes. Then, the ground material was placed in an autoclave at 130°C for 12 hours. After cooling to room temperature, the obtained white solid was washed with 70°C ethanol for 2 hours and dried under vacuum at 150°C for 12 hours. The sample was labeled UiO-66 (i.e. Figure 2 UiO-66(Zr)-green in (b).

[0077] Preparation of UiO-66-NH2:

[0078] ZrOCl2·8H2O (1.5 mmol) was used as a metal precursor and 2-aminoterephthalic acid (1.5 mmol) was mixed and ground at room temperature for 10 minutes. Then, the ground material was placed in an autoclave at 150°C for 12 hours. After cooling to room temperature, the obtained white solid was washed with 70°C ethanol for 2 hours and dried under vacuum at 150°C for 12 hours. The sample was labeled UiO-66-NH2 (also known as Figure 2 UiO-66(Zr)-NH2-green in (b).

[0079] Preparation of UiO-66-NO2:

[0080] The preparation method of UiO-66-NH2 was referred to, except that 2-aminoterephthalic acid was replaced by 2-nitroterephthalic acid, and the sample was labeled UiO-66-NO2 (i.e. Figure 2 UiO-66(Zr)-NO2-green in (b).

[0081] Example 1

[0082] 2 g of polydimethylsiloxane (PDMS) was dissolved in 2 g of heptane to prepare a dissolving solution. Subsequently, the zirconium-based metal organic framework powder UiO-66 was dispersed in 1 mL of heptane and subjected to ultrasonic treatment for 10 minutes. The obtained dispersion was added to the above dissolving solution and stirred for 1 hour. The mass of UiO-66 is 2.5% of PDMS. Subsequently, the uniform liquid was poured into a 5.5×5.5 cm Petri dish, placed at 100°C for 2 hours, and then vacuum treated for 5 minutes. Finally, the membrane was peeled off the Petri dish, and the thickness of the membrane was measured with a micrometer, and the result was 600±0.01 microns. According to the mass of UiO-66 in the casting solution of 0.05 g, the composite membrane was named UiO-66-0.05@PDMS.

[0083] Example 2

[0084] The only difference from Example 1 is that the mass of UiO-66 is 5% of the mass of PDMS, the mass of UiO-66 is 0.1 g, and the obtained composite membrane is named UiO-66-0.1@PDMS.

[0085] Example 3

[0086] The only difference from Example 1 is that UiO-66 is replaced by UiO-66-NH2, and the obtained composite membrane is named UiO-66-NH2-0.05@PDMS.

[0087] Example 4

[0088] The only difference from Example 2 is that UiO-66 is replaced by UiO-66-NH2, and the obtained composite membrane is named UiO-66-NH2-0.1@PDMS.

[0089] Example 5

[0090] The only difference from Example 1 is that UiO-66 is replaced by UiO-66-NO2, and the obtained composite membrane is named UiO-66-NO2-0.05@PDMS.

[0091] Example 6

[0092] The only difference from Example 2 is that UiO-66 is replaced by UiO-66-NO2, and the obtained composite membrane is named UiO-66-NO2-0.1@PDMS.

[0093] Comparative Example 1

[0094] The PDMS membrane was prepared as follows: 2 g of polydimethylsiloxane (PDMS) was dissolved in 2 g of heptane to prepare a solution. Subsequently, the uniform liquid was poured into a 5.5×5.5 cm Petri dish, placed at 100° C. for 2 h, and then vacuum dried for 5 min. Finally, the membrane was peeled off from the Petri dish to obtain a PDMS membrane.

[0095] Structure and performance characterization:

[0096] Figure 2 (a) shows the XRD patterns of different Zr-MOF@PDMS films. Figure 2 (b) shows the XRD patterns of different Zr-MOFs. Figure 2 In the table, SimulatedUiO-66 and SimulatedUiO-66(Zr) both represent the standard XRD patterns of UiO-66. Figure 2 As shown in (b), UiO-66, UiO-66-NO2, and UiO-66-NH2 prepared by the present invention are all typical UiO-66 metal organic framework structures. Figure 2 It was shown that after composite of UiO-66, UiO-66-NO2, and UiO-66-NH2 with PDMS, the Zr-MOFs-0.05@PDMS film showed the same characteristic peaks as the three Zr-MOFs, indicating that the original structure of MOFs was retained in PDMS.

[0097] In order to study the ion selectivity of the film, the current-voltage (IV) curve was measured. The IV graph was used to evaluate and judge the ion transport properties of the Zr-MOFs-0.05@PDMS membrane. The Zr-MOFs-0.05@PDMS membrane was clamped between two cells passing through an H-type electrolytic cell. A total volume of 50.0 mL and a concentration of 1.0 mol·L were injected into both electrolytic cells. -1 Before the measurement, the Zr-MOFs-0.05@PDMS membrane was placed in the relevant solution (concentration of 1.0 mol·L -1 The test results are as follows: Figure 3 shown.

[0098] Figure 3 The IV curve shows the ion separation characteristics of the three Zr-MOFs-0.05@PDMS membranes and PDMS membranes. The slope of the curve corresponds to the ionic conductivity value. The higher the slope of the test membrane, the higher the transmembrane rate of the ions. According to the IV curve results, the separation of sodium ions and calcium ions can be seen. Under gradually increasing voltage, the current response of sodium ions and calcium ions and potassium ions shows obvious differences. The current of calcium ions and potassium ions increases steadily with the increase of voltage, showing a higher ion permeability. In contrast, the current response of sodium ions is relatively weak. Its transmission rate is Ca 2+ >K + >Na + This difference can clearly distinguish the conductivity characteristics of sodium ions, potassium ions, and calcium ions through the IV curve, further verifying the effectiveness of the Zr-MOFs-0.05@PDMS membrane in the separation of monovalent and divalent cations.

[0099] In addition, by Figure 3 It can also be seen that among the four membranes, UiO-66-NH2-0.05@PDMS has the best selectivity (Ca 2+ / Na + ) is 1.21, followed by UiO-66-0.05@PDMS; the separation performance advantage of UiO-66-NO2-0.05@PDMS is not obvious compared with PDMS membrane.

[0100] The separation performance of three Zr-MOFs-0.05@PDMS membranes and PDMS membranes was tested by ion diffusion experiments. The experimental process is as follows: The ion diffusion experiment was carried out in a two-chamber transmission unit separated by a Zr-MOFs-0.05@PDMS membrane. One side of the membrane contained 50 mL of 1.0 mol·L -1 NaCl and 1.0 mol·L -1 The mixed solution of CaCl2 was placed on the other side of the membrane. On the other side of the membrane, there was 50 mL of deionized water. In order to reduce the influence of concentration polarization on the permeation experiment, the two compartments were magnetically stirred at a speed of 500 rpm. Samples were collected regularly from the deionized water side and Ca was evaluated using ICP-OES (Thermo Fisher iCAP 7000). 2+ and Na + The experimental results are shown in Table 1.

[0101] Table 1 Comparison of separation performance of different separation membranes

[0102] Film name <![CDATA[Na + Transfer rate (mol·m -2 ·h -1 )]]> <![CDATA[Selective (Na + / Ca 2+ )]]> PDMS 1.4E-04 4.03 UiO-66-0.05@PDMS 1.87E-04 5.59 <![CDATA[UiO-66-NO2-0.05@PDMS]]> 1.17E-04 2.80 <![CDATA[UiO-66-NH2-0.05@PDMS]]> 2.33E-04 11.2

[0103] As shown in Table 1, compared with the PDMS membrane, the zirconium-based metal organic framework-polydimethylsiloxane composite membranes UiO-66-0.05@PDMS and UiO-66-NH2-0.05@PDMS provided by the present invention have better ion selectivity and higher ion transmission rate; the separation performance of UiO-66-NO2-0.05@PDMS is slightly lower than that of the PDMS membrane, which may be related to the local electronic structure of the functional group of UiO-66-NO2-0.05@PDMS. Figure 3 The results shown are consistent.

[0104] Figure 4 The three Zr-MOFs-0.05@PDMS membranes were shown to have a -1 NaCl and 1 mol·L -1 X-ray diffraction (XRD) pattern after immersion in CaCl2 salt solution for 10 days. Figure 4 It can be seen that the composite membranes of three zirconium-based MOFs (UiO-66, UiO-66-NO2 and UiO-66-NH2) and PDMS can still maintain the same diffraction peaks after being immersed in salt solution for 10 days, and the size of the membrane has almost no expansion or contraction. This shows that the three Zr-MOFs-0.05@PDMS membranes can maintain high stability and anti-pollution in the test environment. After the PDMS membrane was also immersed for 10 days, it was damaged due to swelling and water absorption.

[0105] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Application of a zirconium-based metal organic framework-polydimethylsiloxane composite membrane as a separation membrane in separating monovalent and divalent cations, characterized in that: The zirconium-based metal organic framework-polydimethylsiloxane composite film comprises a polydimethylsiloxane-based base film and a zirconium-based metal organic framework material dispersed in the polydimethylsiloxane-based base film; The zirconium-based metal organic framework material is UiO-66-NH2; The mass of the zirconium-based metal organic framework material is 2.5-10% of the mass of the polydimethylsiloxane-based base film; The method for preparing the zirconium-based metal organic framework-polydimethylsiloxane composite film comprises the following steps: dissolving polydimethylsiloxane in a first organic solvent to obtain a solution; dispersing the zirconium-based metal organic framework material in a second organic solvent to obtain a dispersion; The dispersion liquid is mixed with the dissolving liquid to obtain a casting liquid; the mass of the zirconium-based metal organic framework material in the casting liquid is 2.5-10% of the mass of the polydimethylsiloxane; The casting solution is subjected to film forming to obtain the zirconium-based metal organic framework-polydimethylsiloxane composite film.

2. The use according to claim 1, characterized in that: The preparation method of UiO-66-NH2 comprises the following steps: The zirconium source and the organic ligand are mixed and ground to obtain a mixed powder; the organic ligand is 2-aminoterephthalic acid; The mixed powder is subjected to a coordination reaction in an autoclave to obtain the UiO-66-NH2; the temperature of the coordination reaction is 100-150°C.

3. The use according to claim 2, characterized in that: The molar ratio of Zr to the organic ligand in the zirconium source is 1:

1.

4. The use according to claim 2 or 3, characterized in that: The coordination reaction time is 10 to 24 h.

5. The use according to claim 1, characterized in that: The first organic solvent and the second organic solvent are independently heptane or hexane.

6. The use according to claim 1, characterized in that: The film forming comprises: spreading the film casting solution on a substrate, allowing it to stand, and vacuum treating it to form a zirconium-based metal organic framework-polydimethylsiloxane composite film on the substrate.

7. The use according to claim 1, characterized in that: The mass ratio of the polydimethylsiloxane to the first organic solvent is 1-5:1; the concentration of the zirconium-based metal organic framework material in the dispersion is 0.05-0.1 g / mL.

8. The use according to claim 1, characterized in that: Monovalent cations include Na + and / or K + , divalent cations include Ca 2+ .

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