Functionalized metal-organic framework materials, composite films and methods of making and using the same, heavy metal ion adsorption and detection devices

Abstract

The present application relates to the technical field of heavy metal ion adsorption and detection, and particularly relates to a functionalized metal organic framework material, a composite film, a preparation method and application thereof, and a heavy metal ion adsorption and detection device. The functionalized metal organic framework material provided by the present application has organic ligands with active groups such as pyridine or carboxyl, and has intelligent response to heavy metal ions. The content of the active groups in the MOFs is regulated by regulating the ratio of the organic ligands with active groups and conventional organic ligands, and then the controllable functionalization degree is realized, so that the functionalized metal organic framework material has good intelligent response to heavy metal ions. Meanwhile, the functionalized metal organic framework material has good mechanical properties and stable adsorption effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy metal ion adsorption and detection, and particularly relates to a functionalized metal organic framework material, a composite film and a preparation method and application thereof, and a heavy metal ion adsorption and detection device. BACKGROUND

[0002] How to detect and adsorb heavy metal ions in the ocean is an important problem faced by today's society. Ion selective material is a kind of porous material that plays a key role in the process of detecting and adsorbing heavy metal ions in seawater, and its structure contains active groups such as hydroxyl, alkyl, carboxyl and amino groups that can form ionic bonds or covalent bonds with specific heavy metal ions. At present, a variety of materials have been used to prepare ion selective materials, but these materials have problems such as wide pore size distribution, large transmission resistance and low specific surface area, which result in poor effect of detecting and adsorbing heavy metal ions.

[0003] In recent years, metal organic frameworks (MOFs) as a new type of porous crystalline material have been proposed for the preparation of ion selective materials because of their unique advantages such as clear crystal structure, high porosity, narrow pore size, uniform pore size distribution, high specific surface area and physical and chemical stability. And the adjustable nanopores of MOFs provide an ideal space for various guests to realize multifunctionalization. The high adsorption capacity of heteropolyacid salts such as ammonium phosphomolybdate and ammonium phosphotungstate for rubidium and cesium ions can be encapsulated into MOFs to improve the adsorption performance of rubidium and cesium ions, as in patent CN115703059A. In patent CN112108119B, the MOFs are modified by potassium permanganate to obtain partially oxidized MOFs, and then subjected to anaerobic carbonization modification to improve the porosity and stability of the MOFs and enhance the adsorption capacity of cadmium ions. However, encapsulating charged guests into the MOFs structure may reduce the stability of the MOFs or block the ion transmission channel, and the process of post-modification of the MOFs framework is difficult to control. Moreover, the method of encapsulating inorganic salts capable of adsorbing heavy metal ions into the voids of MOFs and improving the porosity of MOFs can only achieve simple adsorption of heavy metal ions and cannot achieve intelligent response. And the mechanical properties of ion selective materials made of pure MOFs are poor, which affects the stability of the detection and adsorption effect. SUMMARY

[0004] The present application relates to the technical field of heavy metal ion adsorption and detection, and particularly relates to a functionalized metal organic framework material, a composite film and a preparation method and application thereof, and a heavy metal ion adsorption and detection device.

[0005] To achieve the above-mentioned purposes, the present application provides the following technical solutions.

[0006] The present application provides a kind of functional metal organic framework material, the functional metal organic framework material includes organic ligand with active group, conventional organic ligand and metal atom in it;

[0007] The organic ligand with active group includes 、 、 、 、 、 、 、 Or ;

[0008] The conventional organic ligand includes 、 Or ;

[0009] The molar ratio of the organic ligand with active group and conventional organic ligand is (10~0) :(0~10), and the amount of the organic ligand with active group is not 0.

[0010] Preferably, the metal atom includes one or several of zinc, cobalt, zirconium, iron, aluminum and titanium.

[0011] Preferably, the structure of the functional MOFs includes zeolitic imidazolate framework or Uio series framework.

[0012] The zeolitic imidazolate framework is 、 、 、 、 、 、 、 、 、 、 Or ;

[0013] The Uio series framework is 、 、 、 、 、 、 、 、 、 、 Or ;

[0014] The Zr6 is .

[0015] The application further provides a preparation method of the functionalized metal organic framework material.

[0016] The soluble metal salt, the organic ligand with active groups, the conventional organic ligand and the organic solvent are mixed to perform a coordination reaction to obtain the functionalized metal organic framework material.

[0017] Preferably, the soluble metal salt comprises one or more of zinc nitrate hexahydrate, cobalt nitrate hexahydrate, zirconium chloride, iron chloride, aluminum chloride and titanium chloride.

[0018] The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, chloroform, toluene, acetone, diethyl ether, ethyl acetate, isopropanol, methanol and ethanol.

[0019] When the structure of the functionalized metal organic framework material is a zeolitic imidazolate framework, the temperature of the coordination reaction is 20-60 DEG C and the time is 20-40 h.

[0020] When the structure of the functionalized metal organic framework material is a Uio series framework, the temperature of the coordination reaction is 100-150 DEG C and the time is 20-40 h.

[0021] The application further provides an application of the functionalized metal organic framework material or the functionalized metal organic framework material prepared by the preparation method in the field of heavy metal ion adsorption and detection.

[0022] The application further provides a composite film for heavy metal ion adsorption and detection, and the preparation raw material comprises a functionalized metal organic framework material and a polysulfone.

[0023] Preferably, the polysulfone comprises one or more of polyether sulfone, bisphenol A polysulfone and polyaryl sulfone.

[0024] The polyether sulfone is unmodified polyether sulfone or carboxyl-modified polyether sulfone.

[0025] The structural formula of the carboxyl-modified polyether sulfone is as follows:

[0026] ;

[0027] In the structural formula, the value range of x is 0-1, and the value range of y is 0-1.

[0028] The application further provides a preparation method of the heavy metal ion adsorption composite film,

[0029] When the polysulfone is one or more of unmodified polyether sulfone, bisphenol A polysulfone and polyaryl sulfone, the method comprises the following steps:

[0030] The soluble metal salt, the organic ligand with active groups, the conventional organic ligand, the polysulfone and the organic solvent are mixed to perform a coordination reaction, and then cast into a film to obtain the functionalized metal organic framework-polymer composite film.

[0031] When the polysulfone is carboxyl-modified polyether sulfone, the method comprises the following steps:

[0032] The soluble metal salt, the organic ligand with active groups, the conventional organic ligand and the organic solvent are mixed, and then the obtained mixed solution is added with a polyether sulfone base film to perform a coordination reaction, so as to obtain the functionalized metal organic framework-polymer composite film, wherein the functionalized metal organic framework-polymer composite film has a heterogeneous structure.

[0033] The application further provides a heavy metal ion adsorption and detection device, which is characterized by comprising a composite film for heavy metal ion adsorption and detection.

[0034] The composite film for heavy metal ion adsorption and detection is the composite film for heavy metal ion adsorption and detection as described in the above technical solution.

[0035] The application provides a functionalized metal organic framework material, which comprises an organic ligand with active groups, a conventional organic ligand and metal atoms. 、 、 、 、 、 、 、 or ; the conventional organic ligand comprises 、 or The molar ratio of the organic ligand with active groups and the conventional organic ligand is (10-0):(0-10), and the amount of the organic ligand with active groups is not 0. The functionalized metal organic framework material provided by the application has intelligent response to heavy metal ions due to the organic ligand with active groups such as pyridine or carboxyl. The content of the active groups in the MOFs is regulated by regulating the ratio of the organic ligand with active groups and the conventional organic ligand, and then the controllable functionalization degree is realized, so that the good intelligent response to heavy metal ions is achieved.

[0036] The application further provides a composite film for heavy metal ion adsorption and detection, and the preparation raw materials include the functionalized metal organic framework material and the polysulfone.

[0037] The application further provides a preparation method of the heavy metal ion adsorption composite film, and when the polysulfone is one or more of unmodified polyether sulfone, bisphenol A polysulfone and polyaryl sulfone, the method includes the following steps: mixing the soluble metal salt, the organic ligand with active groups, the conventional organic ligand, the polysulfone and the organic solvent, performing coordination reaction, casting into a film, and obtaining the functionalized metal organic framework material-polymer composite film; when the polysulfone is carboxyl-modified polyether sulfone, the method includes the following steps: mixing the soluble metal salt, the organic ligand with active groups, the conventional organic ligand and the organic solvent, then adding the polyether sulfone base film into the obtained mixed solution to perform coordination reaction, and obtaining the functionalized metal organic framework material-polymer composite film, wherein the functionalized metal organic framework material-polymer composite film has a heterogeneous structure.

[0038] The application prepares a composite film by using the functionalized metal organic framework material and the polyether sulfone, and another ion-selective membrane with asymmetric structure is prepared by using the functionalized metal organic framework material and the carboxyl-modified polyether sulfone. The method is that the PES-COOH base film prepared in advance is soaked in the mixed solution of the dispersed three kinds of monomers for a period of time, the MOFs are secondarily grown by using the seed method, and the high composite is realized through the interaction between the carboxyl of the PES-COOH and the metal ions of the MOFs. The prepared composite film has high ion flux, realizes high energy utilization rate, the introduction of the polymer greatly improves the mechanical property, the thermal stability and the chemical stability of the composite film, and the heterogeneous membrane realizes controllable ion transmission. The two composite films provided by the application can be applied to salt differential power generation, detection and adsorption of heavy metal ions, and the devices for detecting heavy metal ions are prepared based on the two composite films. The process of detecting and adsorbing heavy metal ions in seawater and utilizing marine energy can be combined, one film is used for multiple purposes, and good application value is achieved.

[0039] The application provides a preparation method of functionalized MOFs and a preparation method of a composite film integrated with a polymer, and the prepared composite film has high application value in salt difference power generation, heavy metal ion detection and adsorption and the like. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 SEM image of the non-functionalized metal organic framework material (ZIF-8) described in Comparative Example 1;

[0041] Figure 2 XRD image of the non-functionalized metal organic framework material (ZIF-8) described in Comparative Example 1;

[0042] Figure 3 SEM image of the functionalized metal organic framework material (ZIF-8-COOH5) described in Example 1;

[0043] Figure 4 SEM image of the functionalized metal organic framework material (Uio-67-BPY 10 ) prepared in Example 14;

[0044] Figure 5 Nitrogen adsorption / desorption isotherm of the functionalized metal organic framework material (Uio-67-BPY 10 ) prepared in Example 14;

[0045] Figure 6 Pore size distribution of the functionalized metal organic framework material (Uio-67-BPY 10 ) prepared in Example 14;

[0046] Figure 7 XRD image of the functionalized metal organic framework material (Uio-67-BPY 10 ) prepared in Example 14;

[0047] Figure 8 Top view SEM image of the heavy metal ion adsorption composite film described in Example 20;

[0048] Figure 9 Cross-sectional SEM image of the heavy metal ion adsorption composite film described in Example 20;

[0049] Figure 10 Cross-sectional SEM image of the heavy metal ion adsorption composite film described in Example 21;

[0050] Figure 11 The heavy metal ion adsorption composite film provided in Example 22 is under 50 times concentration difference condition, and the curve graphs of load resistance, current density output and power density are shown.

[0051] Figure 12 Ion current rectification curve of the heavy metal ion adsorbing composite film provided for Example 22 in the same concentration of electrolyte solution;

[0052] Figure 13 The ion selective membrane provided for Test Example 3 after adsorbing copper ions under the condition of 50 times of concentration difference, the curve of load resistance and current density output and power density;

[0053] Figure 14 The ion selective membrane provided for Test Example 3 after adsorbing copper ions under the condition of 50 times of concentration difference, the curve of load resistance and current density output and power density;

[0054] Figure 15 The device structure schematic diagram for heavy metal ion adsorbing or detecting of the heavy metal ion adsorbing composite film described in the application. DETAILED DESCRIPTION

[0055] The application provides a functionalized metal organic framework material, the functionalized metal organic framework material comprising an organic ligand with active groups, a conventional organic ligand and metal atoms;

[0056] The organic ligand with active groups comprises , , , , , , , or ;

[0057] The conventional organic ligand comprises , or ;

[0058] The molar ratio of the organic ligand with active groups to the conventional organic ligand is (10-0):(0-10), and the amount of the organic ligand with active groups is not 0.

[0059] In the application, the molar ratio of the organic ligand with active groups to the conventional organic ligand is (10-0):(0-10), preferably (8-2):(2-8), and more preferably (6-4):(4-6).

[0060] In the application, the metal atoms preferably comprise one or more of zinc, cobalt, zirconium, iron, aluminum and titanium; when the metal atoms are two or more of the above-mentioned specific choices, the application does not have any special limitation on the ratio of the above-mentioned specific substances, and the mixing can be carried out in any ratio.

[0061] In the present application, the structure of the functionalized MOFs preferably comprises a zeolitic imidazolate framework or a Uio series framework;

[0062] The zeolitic imidazolate framework is preferably 、 、 、 、 、 、 、 、 、 、 or ;

[0063] The Uio series framework is preferably 、 、 、 、 、 、 、 、 、 、 or ; the Zr6 is preferably .

[0064] The present application also provides a preparation method of the functionalized metal organic framework material described in the above technical solution, comprising the following steps:

[0065] Mixing a soluble metal salt, an organic ligand with active groups, a conventional organic ligand and an organic solvent to perform a coordination reaction to obtain the functionalized metal organic framework material.

[0066] In the present application, all the raw materials for preparation are commercially available products well known to those skilled in the art, unless otherwise specified.

[0067] In the present application, the soluble metal salt comprises one or more of zinc nitrate hexahydrate, cobalt nitrate hexahydrate, zirconium chloride, iron chloride, aluminum chloride and titanium chloride; when the soluble metal salt is two or more of the above specific choices, the present application does not have any special limitation on the ratio of the above specific substances, and mixing in any ratio can be performed.

[0068] In the present application, the organic ligand with active groups comprises 、 、 、 、 、 、 , or ;

[0069] The conventional organic ligand includes , or .

[0070] In the present application, the organic solvent is preferably one or several of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, chloroform, toluene, acetone, diethyl ether, ethyl acetate, isopropyl alcohol, methanol and ethanol; when the organic solvent is two or more of the above-mentioned specific choices, the present application does not have any special limitation on the ratio of the above-mentioned specific substances, and mixing in any ratio can be carried out.

[0071] In the present application, when the structure of the functionalized metal organic framework material is Uio series framework, the mixed raw material further preferably includes acetic acid, and the acetic acid serves to adjust the crystallinity and the grain size. The ratio of the total amount of the organic ligand with active groups and the conventional organic ligand to the amount of acetic acid is preferably 8 mmol:12 mL.

[0072] The present application does not have any special limitation on the mixing process, and the process well known to those skilled in the art can be carried out.

[0073] In the present application, when the structure of the functionalized metal organic framework material is zeolitic imidazolate framework, the temperature of the coordination reaction is preferably 20-60℃, more preferably 30-50℃, and most preferably 35-45℃; and the time is preferably 20-40 h, more preferably 25-35 h, and most preferably 28-32 h.

[0074] In the present application, when the structure of the functionalized metal organic framework material is Uio series framework, the coordination reaction is carried out in a high-pressure reaction kettle, and the temperature of the coordination reaction is preferably 100-150℃, more preferably 110-140℃, and most preferably 120-130℃; and the time is preferably 20-40 h, more preferably 25-35 h, and most preferably 28-32 h.

[0075] After the completion of the coordination reaction, the present application further preferably includes sequentially carried out centrifugal washing and drying; the number of times of the centrifugal washing is preferably 3-6, more preferably 4-5; the temperature of the drying is preferably 80-140℃, more preferably 90-130℃, and most preferably 100-120℃; and the time is preferably 20-30 h, more preferably 22-28 h, and most preferably 24-26 h.

[0076] The application further provides application of the functionalized metal organic framework material in heavy metal ion adsorption and detection.

[0077] The application further provides a composite film for heavy metal ion adsorption and detection, and raw materials for preparation include the functionalized metal organic framework material and polysulfone; the functionalized metal organic framework material is the functionalized metal organic framework material in the above technical solution or the functionalized metal organic framework material prepared by the preparation method in the above technical solution.

[0078] In the application, the polysulfone preferably includes one or more of polyether sulfone, bisphenol A polysulfone and polyaryl sulfone; when the polysulfone is two or more of the above specific choices, the application does not have any special limitation on the ratio of the above specific substances, and mixing in any ratio can be used; the polyether sulfone is preferably unmodified polyether sulfone or carboxyl modified polyether sulfone; the structural formula of the carboxyl modified polyether sulfone is preferably as follows:

[0079]

[0080] In the structural formula, the value range of x is preferably 0-1, and the value range of y is preferably 0-1.

[0081] In the application, the mass ratio of the functionalized metal organic framework material to the polysulfone is preferably (6-1):1, more preferably (4-2):1, and most preferably 3:1.

[0082] The application further provides a preparation method of the heavy metal ion adsorption composite film in the above technical solution; when the polysulfone is one or more of unmodified polyether sulfone, bisphenol A polysulfone and polyaryl sulfone, the method includes the following steps:

[0083] The soluble metal salt, the organic ligand with active groups, the conventional organic ligand, the polysulfone and the organic solvent are mixed to perform coordination reaction, and the functionalized metal organic framework material-polymer composite film is obtained by casting.

[0084] When the polysulfone is carboxyl modified polyether sulfone, the method includes the following steps:

[0085] The soluble metal salt, the organic ligand with active groups, the conventional organic ligand and the organic solvent are mixed, and then the polyether sulfone base film is added to the obtained mixed solution to perform coordination reaction, so as to obtain the functionalized metal organic framework material-polymer composite film, and the functionalized metal organic framework material-polymer composite film has a heterogeneous structure.

[0086] In the present application, when the polysulfone is one or more of unmodified polyether sulfone, bisphenol A polysulfone and polyaryl sulfone, the following steps are included:

[0087] The soluble metal salt, the organic ligand with active groups, the conventional organic ligand, the polysulfone and the organic solvent are mixed to perform a coordination reaction, and then cast into a film to obtain the functionalized metal organic framework-polymer composite film.

[0088] In the present application, the mixing is preferably performed under ultrasonic conditions, and the present application does not have any special limitation on the frequency of the ultrasonic, which can be performed using a frequency well known to those skilled in the art. In the present application, the process of the ultrasonic is the coordination reaction, which is preferably defined with reference to the functionalized metal organic framework, and will not be repeated here.

[0089] In the present application, the casting into a film is preferably that the mixed solution obtained by the coordination reaction is cast on a clean glass plate, and then transferred to a vacuum oven for drying. In the present application, the temperature of the drying is preferably 60-150°C, more preferably 80-130°C, and most preferably 100-110°C; and the time of the drying is preferably 10-40 h, more preferably 20-30 h.

[0090] In the present application, the types and proportions of the soluble metal salt, the organic ligand with active groups, the conventional organic ligand and the organic solvent are preferably defined with reference to the types and proportions of the raw materials for preparing the functionalized metal organic framework, and will not be repeated here.

[0091] In the present application, when the polyether sulfone is a carboxyl-modified polyether sulfone, the following steps are included:

[0092] The soluble metal salt, the organic ligand with active groups, the conventional organic ligand and the organic solvent are mixed, and then the polyether sulfone base film is added to the obtained mixed solution to perform a coordination reaction, so as to obtain the functionalized metal organic framework-polymer composite film, which has a heterogeneous structure.

[0093] In the present application, the types and proportions of the soluble metal salt, the organic ligand with active groups, the conventional organic ligand and the organic solvent, and the coordination reaction are preferably defined with reference to the types and proportions of the raw materials for preparing the functionalized metal organic framework, and the coordination reaction, and will not be repeated here.

[0094] The preparation process of the polyether sulfone base film is not particularly limited in the present application, and can be carried out by using a process well known to those skilled in the art. In the embodiment of the present application, the preparation process of the polyether sulfone base film is specifically as follows: 0.1 g of carboxyl-modified polyether sulfone is uniformly dissolved in 10 mL of N-methylpyrrolidone to prepare a 0.1 g / mL solution, the solution is cast on a glass plate, the glass plate is transferred to a vacuum oven, slowly heated to 120 DEG C after constant temperature at 60 DEG C for 15 h, and heated and dried at 120 DEG C under vacuum for 12 h to fully remove the solvent, and the glass plate is taken out after drying to obtain a polyether sulfone base film.

[0095] In the present application, the soaking time is preferably 3-10 min, and more preferably 3-5 min.

[0096] In the present application, the PES-COOH base film prepared in advance is soaked in a mixed solution of the three monomers dispersed for a period of time to grow MOFs by seed method, and the soaking time is sufficient to ensure that the carboxylic acid groups on the PES-COOH can interact well with the metal ions in the MOFs, so that the MOFs can be well adsorbed to the base film, thereby forming the required ion-selective membrane with asymmetric structure.

[0097] The present application also provides a heavy metal ion adsorption and detection device, comprising a composite film for heavy metal ion adsorption and detection; the composite film for heavy metal ion adsorption and detection is the composite film for heavy metal ion adsorption and detection described in the above technical solution.

[0098] In the present application, the heavy metal ion adsorption and detection device comprises two electrolyte pools, and the composite film for heavy metal ion adsorption and detection is fixed at the connection of the two electrolyte pools to separate the electrolytes on both sides; electrodes are respectively placed in the two electrolyte pools, and the electrodes are preferably Ag| AgCl electrodes, Pt electrodes or C electrodes, and more preferably Ag| AgCl electrodes; the electrolytes in the two electrolyte pools are preferably potassium chloride solution or sodium chloride solution, and more preferably potassium chloride solution.

[0099] The functionalized metal organic framework material, the preparation method and application thereof, and the heavy metal ion adsorption composite film and the preparation method thereof provided by the present application will be described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0100] Example 1

[0101] 5 mmol zinc nitrate hexahydrate, 3 mmol 2-methylimidazole and 3 mmol 2-methyl-3-carboxyimidazole were uniformly dispersed in 180 mL of N,N-dimethylformamide solvent to obtain a mixed solution;

[0102] The mixed solution was reacted at room temperature for 24 h, filtered, and the obtained solid product was washed by centrifugation with methanol (MeOH) for 3 times to remove unreacted reactants on the surface of the product while activating the product, and dried in a vacuum oven at 120°C for 24 h to constant weight to obtain a functionalized metal organic framework material (denoted as ZIF-8-COOH5); the structural formula of the ZIF-8-COOH5 is .

[0103] Comparative Example 1

[0104] Reference Example 1, except that the amount of 2-methylimidazole was replaced by 6 mmol, and the amount of 2-methyl-3-carboxyimidazole was replaced by 0 mmol to obtain an unfunctionalized metal organic framework material (denoted as ZIF-8); the structural formula of the unfunctionalized metal organic framework material is .

[0105] Figure 1 The SEM image of the unfunctionalized metal organic framework material (ZIF-8) described in Comparative Example 1, from Figure 1 It can be seen that the ZIF-8 crystal structure is complete;

[0106] Figure 2 The XRD image of the unfunctionalized metal organic framework material (ZIF-8) described in Comparative Example 1, from Figure 2 It can be seen that the ZIF-8 is successfully prepared;

[0107] Figure 3 The SEM image of the functionalized metal organic framework material (ZIF-8-COOH5) described in Example 1, from Figure 3 It can be seen that the crystal structure of the functionalized ZIF-8 has defects.

[0108] Example 2

[0109] Reference Example 1, except that the amount of 2-methylimidazole was replaced by 0 mmol, and the amount of 2-methyl-3-carboxyimidazole was replaced by 6 mmol to obtain a completely functionalized metal organic framework material (denoted as ZIF-8-COOH 10 ); the structural formula of the completely functionalized organic framework is .

[0110] Example 3

[0111] Reference Example 1, except that 3 mmol of 2-methyl-3-carboxyimidazole was replaced by 3 mmol of 2-methyl-3-aminimidazole to obtain a functionalized metal organic framework material (denoted as ZIF-8-NH2 2-5 ); the structural formula of the functionalized metal organic framework material is .

[0112] Example 4

[0113] Reference Example 1, except that 3 mmol of 2-methyl-3-carboxyimidazole was replaced by 3 mmol of 2-aminomethylimidazole to obtain a functionalized metal organic framework material (denoted as ZIF-8-NH2 -5 ); the structural formula of the functionalized metal organic framework material is .

[0114] Example 5

[0115] 5 mmol of cobalt nitrate hexahydrate, 3 mmol of 2-methylimidazole and 3 mmol of 2-methyl-3-carboxyimidazole were uniformly dispersed in 180 mL of N,N-dimethylformamide solvent to obtain a mixed solution;

[0116] The mixed solution was reacted at room temperature for 24 h, filtered, and the obtained solid product was washed by centrifugation with methanol (MeOH) for 3 times to remove unreacted reactants on the surface of the product while activating the product, and dried in a vacuum oven at 120°C for 24 h to constant weight to obtain a functionalized metal organic framework material (denoted as ZIF-67-COOH5); the structural formula of the ZIF-67-COOH5is .

[0117] Comparative Example 2

[0118] Reference Example 5, except that the amount of 2-methylimidazole was replaced by 6 mmol, and the amount of 2-methyl-3-carboxyimidazole was replaced by 0 mmol to obtain an unfunctionalized metal organic framework material (denoted as ZIF-67); the structural formula of the unfunctionalized metal organic framework material is .

[0119] Example 6

[0120] Reference Example 5, except that the amount of 2-methylimidazole was replaced by 0 mmol, and the amount of 2-methyl-3-carboxyimidazole was replaced by 6 mmol to obtain a completely functionalized metal organic framework material (denoted as ZIF-67-COOH 10 ); the structural formula of the functionalized metal organic framework material is .

[0121] Example 7

[0122] With reference to Example 5, the difference is that 3 mmol of 2-methyl-3- carboxy imidazole is replaced by 3 mmol of 2-methyl-3-amino imidazole to obtain a functionalized metal organic framework material (denoted as ZIF-67-NH2 2-5 ); the structural formula of the functionalized metal organic framework material is .

[0123] Example 8

[0124] With reference to Example 5, the difference is that 3 mmol of 2-methyl-3- carboxy imidazole is replaced by 3 mmol of 2-amino methyl imidazole to obtain a functionalized metal organic framework material (denoted as ZIF-67-NH2 -5 ); the structural formula of the functionalized metal organic framework material is .

[0125] Example 9

[0126] 5 mmol of zirconium chloride, 4 mmol of terephthalic acid, 4 mmol of 1,2,4- benzene tricarboxylic acid and 12 mL of acetic acid are dispersed in 80 mL of N,N- dimethylformamide (DMF), the solution is mixed thoroughly under ultrasonic at 25 °C for 20 min, the obtained mixture is transferred to a 100 mL stainless steel liner reaction kettle, and is reacted at 120 °C for 24 h, and then is cooled to room temperature, filtered, and the obtained solid product is washed with DMF and methanol respectively for 3 times by centrifugation to remove the unreacted reactants on the surface of the product and to activate the product, and then is dried in a vacuum oven at 80 °C for 12 h to constant weight to remove the solvent, to obtain a functionalized metal organic framework material (denoted as Uio-66-COOH5), the structural formula of the functionalized metal organic framework material is

[0127] Uio-66-COOH5), the structural formula of the functionalized metal organic framework material is .

[0128] Comparative Example 3

[0129] With reference to Example 9, the difference is that the amount of the terephthalic acid is replaced by 8 mmol, and the amount of the 1,2,4-benzene tricarboxylic acid is replaced by 0 mmol, to obtain an unfunctionalized metal organic framework material (denoted as Uio-66); the structural formula of the unfunctionalized metal organic framework material is .

[0130] Example 10

[0131] Reference Example 9, except that the amount of the terephthalic acid is replaced by 0 mmol, and the amount of the 1,2,4-benzenetricarboxylic acid is replaced by 8 mmol, to obtain a functionalized metal-organic framework material (denoted as Uio-66-COOH 10 ); the structural formula of the functionalized metal-organic framework material is .

[0132] Example 11

[0133] Reference Example 9, except that 4 mmol of 1,2,4-benzenetricarboxylic acid is replaced by 4 mmol of 2-amino-1,4-benzenedicarboxylic acid, to obtain a functionalized metal-organic framework material (denoted as Uio-66-NH 2-5 ); the structural formula of the functionalized metal-organic framework material is .

[0134] Example 12

[0135] Reference Example 9, except that 4 mmol of 1,2,4-benzenetricarboxylic acid is replaced by 4 mmol of 2,5-pyridinedicarboxylic acid, to obtain a functionalized metal-organic framework material (denoted as Uio-66-BPY5); the structural formula of the functionalized metal-organic framework material is .

[0136] Example 13

[0137] 5 mmol of zirconium chloride, 4 mmol of 4,4'-biphenyldicarboxylic acid, 4 mmol of 2,2'-bipyridine-4,4'-dicarboxylic acid and 12 mL of acetic acid are dispersed in 80 mL of N,N-dimethylformamide (DMF), and the solution is mixed thoroughly by ultrasonic treatment at 25 °C for 20 min, and the obtained mixture is transferred into a 100 mL stainless steel inner liner reaction kettle, and reacted at 120 °C for 24 h, and cooled to room temperature, and filtered, and the obtained solid product is washed with DMF and methanol respectively by centrifugation for 3 times to remove the unreacted reactants on the surface of the product and to activate the product, and dried in a vacuum oven at 100 °C for 12 h to constant weight to remove the solvent, to obtain a functionalized metal-organic framework material (denoted as Uio-67-BPY5), and the structural formula of the functionalized metal-organic framework material is .

[0138] Comparative Example 4

[0139] Reference Example 13, except that the amount of 4,4'-biphenyldicarboxylic acid is replaced by 8 mmol, and the amount of 2,2'-bipyridine-4,4'-dicarboxylic acid is replaced by 0 mmol; to obtain an unfunctionalized metal-organic framework material (denoted as Uio-67); the structural formula of the unfunctionalized metal-organic framework material is .

[0140] Example 14

[0141] Referring to Example 13, the difference is that the amount of 4,4'-biphenyldicarboxylic acid was replaced with 0 mmol, and the amount of 2,2'-bipyridine-4,4'-dicarboxylic acid was replaced with 8 mmol; thus, a functionalized metal-organic framework material (denoted as Uio-67-BPY) was obtained. 10 The structural formula of the fully functionalized metal-organic framework material is as follows: .

[0142] Example 15

[0143] Referring to Example 13, the difference is that 2,2'-bipyridine-4,4'-dicarboxylic acid is replaced with 3,3'-diamino-4,4'-biphenyldicarboxylic acid, resulting in a functionalized metal-organic framework material (denoted as Uio-67-NH). 2-5 The structural formula of the functionalized metal-organic framework material is as follows: .

[0144] Example 16

[0145] Referring to Example 13, the difference is that 2,2'-bipyridine-4,4'-dicarboxylic acid is replaced with 3-carboxy-4,4'-biphenyldicarboxylic acid, resulting in a functionalized metal-organic framework material (denoted as Uio-67-COOH5); the structural formula of the functionalized metal-organic framework material is as follows: .

[0146] Figure 4 The functionalized metal-organic framework material (Uio-67-BPY) prepared in Example 14 10 The SEM image of ) is from Figure 4 It can be seen that Uio-67-BPY 10 Successful preparation;

[0147] Figure 5 The functionalized metal-organic framework material (Uio-67-BPY) prepared in Example 14 10 The nitrogen adsorption / desorption isotherm. Figure 6 The functionalized metal-organic framework material (Uio-67-BPY) prepared in Example 14 10 The aperture distribution of ) is determined by Figures 5~6 It can be seen that Uio-67-BPY 10 Its specific surface area is 505.92 m². 2 / g, pore size distribution shows Uio-67-BPY 10 It has a 10.9 Å window, close to the ideal aperture;

[0148] Figure 7 XRD pattern of the functionalized metal organic framework material (Uio-67-BPY 10 ) prepared for Example 14, from which it can be known that the Uio-67-BPY 10 is successfully prepared. Figure 7

[0149] Example 17

[0150] After 5 mmol of zinc nitrate hexahydrate, 3 mmol of 2-methyl imidazole, 3 mmol of 2-methyl-3-carboxy imidazole and 5 mmol of polyether sulfone are respectively uniformly dispersed in 10 mL of N-methyl pyrrolidone (NMP) solvent, they are mixed and ultrasonic dispersion treated at 80°C for 1 h to obtain a uniformly dispersed mixed solution. The mixed solution is cast on a clean glass plate, and then the glass plate is transferred to a vacuum oven and dried at 80°C for 24 h to fully volatilize the solvent, thereby obtaining a heavy metal ion adsorption composite film (denoted as ZIF-8-COOH5 / PES).

[0151] Example 18

[0152] Referring to Example 17, the difference is that 2-methyl-3-carboxy imidazole is replaced by 2-methyl-3-amino imidazole to obtain a heavy metal ion adsorption composite film.

[0153] Example 19

[0154] Referring to Example 17, the difference is that 2-methyl-3-carboxy imidazole is replaced by 2-aminomethyl imidazole to obtain a heavy metal ion adsorption composite film.

[0155] Example 20

[0156] After 5 mmol of zirconium chloride, 4 mmol of 4,4'-biphenyldicarboxylic acid, 4 mmol of 2,2'-bipyridine-4,4'-dicarboxylic acid and 0.1 g of polyether sulfone are respectively uniformly dispersed in 10 mL of N-methyl pyrrolidone solvent, they are then ultrasonic dispersion treated at 80°C for 1 h to obtain a uniformly dispersed mixed solution. The mixed solution is cast on a clean glass plate, and then the glass plate is transferred to a vacuum oven and dried at room temperature for 24 h to fully volatilize the solvent, thereby obtaining a heavy metal ion adsorption composite film (denoted as Uio-67-BPY 10 / PES).

[0157] Figure 8 The top view SEM image of the heavy metal ion adsorption composite film described in Example 20, from which it can be known that the MOF and polyether sulfone are uniformly mixed, and the film surface has no obvious defects; Figure 8 ​​

[0158] Figure 9 The cross-sectional SEM image of the heavy metal ion adsorption composite film described in Example 20 is shown in FIG. 4. Figure 9 As can be seen from FIG. 4, the MOF and the polyether sulfone are mixed uniformly.

[0159] Example 21

[0160] 0.1 g of carboxyl-modified polyether sulfone was uniformly dissolved in 10 mL of N-methylpyrrolidone to prepare a 0.1 g / mL solution, the solution was cast onto a glass plate, and the glass plate was transferred to a vacuum oven. After constant temperature at 60°C for 15 h, the temperature was slowly increased to 120°C, and the glass plate was heated and dried at 120°C under vacuum for 12 h to sufficiently remove the solvent. After drying was completed, the glass plate was removed, and the obtained carboxyl-modified polyether sulfone film was immersed in a mixed 10 mL of N,N-dimethylformamide solution containing 5 mmol of zinc nitrate hexahydrate, 3 mmol of 2-methylimidazole, and 3 mmol of 2-methyl-3-carboxyimidazole at room temperature for 3 min. After immersion was completed, the glass plate was transferred to a vacuum oven at 60°C and dried for 12 h to obtain a heavy metal ion adsorption composite film (denoted as ZIF-8-COOH5 / PES-COOH).

[0161] Figure 10 The cross-sectional SEM image of the heavy metal ion adsorption composite film described in Example 21 is shown in FIG. 5. Figure 10 As can be seen from FIG. 5, the MOF was successfully grown on the polyether sulfone film to form a heterostructure.

[0162] Example 22

[0163] 0.1 g of carboxyl-modified polyether sulfone was uniformly dissolved in 10 mL of N-methylpyrrolidone to prepare a 0.1 g / mL solution, the solution was cast onto a glass plate, and the glass plate was transferred to a vacuum oven. After constant temperature at 60°C for 15 h, the temperature was slowly increased to 120°C, and the glass plate was heated and dried at 120°C under vacuum for 12 h to sufficiently remove the solvent. After drying was completed, the glass plate was removed, and the obtained carboxyl-modified polyether sulfone film was immersed in a mixed 10 mL of N,N-dimethylformamide solution containing 5 mmol of zinc nitrate hexahydrate, 3 mmol of 2-methylimidazole, and 3 mmol of 2-methyl-3-carboxyimidazole at room temperature for 3 min. After immersion was completed, the glass plate was transferred to a vacuum oven at 60°C and dried for 12 h to obtain a heavy metal ion adsorption composite film (denoted as ZIF-8-COOH5 / PES-COOH). 10

[0164] Test Example 1

[0165] As Figure 15 ​As shown, the heavy metal ion adsorption composite film prepared in Example 22 was fixed at the connection of two solution pools to separate the solutions on both sides, thus constructing an asymmetric concentration gradient. Specifically, potassium chloride solutions with concentrations of 0.5 M and 0.01 M were added to the two solution pools as electrolytes, respectively. Ag|AgCl electrodes were placed on both sides of the membrane to provide transmembrane potential and connected to a Keithley 6487 picoammeter to measure the ion current passing through the membrane. This constructed a salinity gradient power generation device, using a 50-fold concentration gradient (0.5 M|0.01 M) to simulate the conditions of seawater and freshwater rivers.

[0166] Figure 11 The graphs showing the load resistance versus current density output and power density of the heavy metal ion adsorption composite thin film provided in Example 22 under a 50-fold concentration difference condition are provided by [the relevant authority / organization]. Figure 11 It can be seen that as the load resistance increases, the current density gradually decreases, and the output power density reaches its maximum of 6.20 W / m when the load resistance is 2000 kΩ. 2 .

[0167] Test Example 2

[0168] like Figure 15 As shown, the heavy metal ion adsorption composite film prepared in Example 22 was fixed at the junction of two solution pools to separate the solutions on both sides. Potassium chloride solution of the same concentration (0.01 M) was added to both solution pools as the electrolyte. Ag|AgCl electrodes were placed on both sides of the membrane to provide transmembrane potential and connected to a Keithley 6487 picoammeter to measure the ion current passing through the membrane, thus constructing an ion current rectifier device. A certain voltage was applied through the electrodes to obtain the current under a specific voltage condition.

[0169] Figure 12 The graph shows the ion current rectification curve of the heavy metal ion adsorption composite film provided in Example 22 in an electrolyte solution of the same concentration. Figure 12 It can be seen that in a 0.1 M potassium chloride solution, the ion current rectification ratio of the heavy metal ion adsorption composite film is approximately 2.5.

[0170] Test Example 3

[0171] A series of gradient concentrations (20-600 mg / L, with 20 mg / L as a gradient increase) of copper (II) solution was prepared, and the heavy metal ion adsorption composite membrane provided in Example 22 was immersed in the above-mentioned gradient copper (II) solution for 2 h to ensure that the adsorption could reach equilibrium. After the adsorption equilibrium, the membrane was taken out of the solution and washed with deionized water for 3 times to remove the copper ions attached to the surface of the membrane, and then it was applied in the salt difference power device constructed in Test Example 1 for comparison with the salt difference power of the membrane without the same ion adsorption. The ion-selective membrane saturated with adsorption was immersed in 5 M hydrochloric acid for 2 h, and the adsorbed heavy metal ions were washed away. Then it was taken out and rinsed with deionized water to remove the acid liquid on the surface of the membrane, so as to realize the regeneration of the ion-selective membrane.

[0172] Figure 13 The ion-selective membrane after adsorbing copper ions provided for this test example was loaded with a resistance under a 50-fold concentration difference condition, and the current density output and power density curve was obtained. Figure 11 and Figure 13 It can be seen from the comparison that the current density and output power density output by the ion-selective membrane after adsorbing copper ions under a 50-fold concentration difference condition are lower than those of the ion-selective membrane without adsorbing copper ions when loaded with the same resistance. This is because after adsorbing copper ions, the pore size is occupied by copper ions, and the energy conversion capacity will decrease.

[0173] Figure 14 The regenerated ion-selective membrane was loaded with a resistance under a 50-fold concentration difference condition, and the current density output and power density curve was obtained. Figure 13 and Figure 14 It can be seen from the comparison that the heavy metal ion-selective membrane provided has good regenerability.

[0174] Test Example 4

[0175] As shown in Figure 15 , the heavy metal ion adsorption composite membrane prepared in Example 20 was fixed at the connection of the two solution pools to separate the solutions on both sides, and the same concentration of potassium chloride solution was added to the two solution pools as electrolyte, which was determined to be 0.01 M. The Ag| AgCl electrode was placed on both sides of the membrane to provide a transmembrane potential, and was connected with Keithley 6487 picoammeter. A certain voltage was applied to obtain the current under the condition of a certain voltage, that is, a heavy metal ion detection device was constructed. After adding a nickel (II) solution containing a national emission standard concentration of 0.5 mg / L, a certain voltage was applied, and the current corresponding to the condition of a certain voltage was compared with the current measured when no nickel ion was added. If it decreases, it means that the presence of nickel ion is detected.

[0176] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A heavy metal ion detecting device, characterized by, Two electrolyte pools are included; A composite film is fixed at the connection of the two electrolyte pools to separate the electrolytes on both sides; An electrode is placed in each of the two electrolyte pools, and the electrode is an Ag| AgCl electrode, a Pt electrode, or a C electrode; The electrolyte in the two electrolyte pools is a potassium chloride solution or a sodium chloride solution; The preparation method of the composite film comprises the following steps: Zirconium chloride, 4,4'-diphenyldicarboxylic acid, 2,2'-bipyridine-4,4'-dicarboxylic acid, and an organic solvent are mixed, then a polyethersulfone base film is added to the obtained mixed solution for coordination reaction to obtain the functionalized metal organic framework-polymer composite film, and the functionalized metal organic framework-polymer composite film has a heterostructure; The polyethersulfone is a carboxyl-modified polyethersulfone; The structural formula of the carboxyl-modified polyethersulfone is: ； In the structural formula, the value range of x is 0-1, the value range of y is 0-1, and x is not 0.

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