A functionalized NH2-MIL-125 (Ti) based material, a preparation method and application thereof

Abstract

The application relates to the technical field of material preparation, and particularly discloses a functional NH2-MIL-125(Ti) based material, a preparation method and application thereof. The application provides the following steps: firstly, under the action of an organic base catalyst, imidazole groups are grafted to the amino groups of NH2-MIL-125(Ti) to obtain imidazole grafted NH2-MIL-125(Ti); and then, the imidazole modified NH2-MIL-125(Ti) material is subjected to a coordination reaction with bromoalkane to obtain the functional NH2-MIL-125(Ti) based material. The functional NH2-MIL-125(Ti) based material provided by the application has the advantages of large adsorption capacity, high selectivity, fast adsorption rate, high reduction efficiency and stable structure in adsorbing and reducing noble metals, and provides a potential solution for the recycling of noble metals.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and in particular to a functionalized NH2-MIL-125(Ti)-based material, its preparation method, and its application. Background Technology

[0002] In today's society, precious metals are widely used in many fields such as electronics, chemicals, jewelry, and medicine due to their unique physicochemical properties, such as high conductivity, chemical stability, and catalytic activity. However, the reserves of precious metals in nature are limited and unevenly distributed. Their mining and refining processes are not only costly but also have serious negative impacts on the environment. With the large-scale generation of electronic waste and other waste containing precious metals, the recycling and reuse of precious metals has become a key way to alleviate resource shortages and environmental pressures. Traditional precious metal recycling methods, such as chemical precipitation, ion exchange, and solvent extraction, have many limitations. For example, chemical precipitation has a low recovery rate and easily generates a large amount of waste residue; ion exchange has poor selectivity and is difficult to achieve efficient separation of multiple precious metals; solvent extraction requires the use of large amounts of volatile and toxic organic solvents, posing safety hazards and environmental pollution risks.

[0003] Metal-organic frameworks (MOFs), as novel porous materials, have shown great potential in gas storage, separation, and catalysis in recent years. Among them, NH2-MIL-125(Ti), with its unique structure and abundant amino functional groups, offers a new approach to solving the problem of precious metal recycling. It possesses a large specific surface area and a regular pore structure, which is conducive to the adsorption and diffusion of precious metal ions. However, current research and applications of NH2-MIL-125(Ti) in precious metal recycling are relatively limited, and it suffers from limitations such as limited adsorption capacity, insufficient selectivity, and the need to improve stability. Therefore, developing a functionalized NH2-MIL-125(Ti) material capable of efficiently and selectively recycling precious metals has significant practical implications and broad application prospects. Summary of the Invention

[0004] To address the limitations of existing technologies in the application of NH2-MIL-125(Ti) in the recycling and reuse of precious metals, such as limited adsorption capacity, insufficient selectivity, and the need to improve stability, this invention provides a functionalized NH2-MIL-125(Ti)-based material, its preparation method, and its application.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a functionalized NH2-MIL-125(Ti)-based material, comprising the following steps:

[0007] Step a: Disperse NH2-MIL-125(Ti) in an organic solvent, add an organic base catalyst and N,N-carbonyldiimidazole, and carry out a grafting reaction to obtain imidazole-modified NH2-MIL-125(Ti) material;

[0008] Step b: Disperse the imidazole-modified NH2-MIL-125(Ti) material in an organic solvent, add bromoalkane, and carry out a coordination reaction to obtain the functionalized NH2-MIL-125(Ti)-based material.

[0009] Compared to existing technologies, the method for preparing functionalized NH2-MIL-125(Ti)-based materials provided by this invention first involves grafting imidazole groups onto the amino group of NH2-MIL-125(Ti) under the action of an organic base catalyst. The introduction of the imidazole group significantly enriches the active sites on the surface of the NH2-MIL-125(Ti) material. Simultaneously, the nitrogen atom on the imidazole ring possesses a lone pair of electrons, enabling it to form a strong coordination interaction with noble metal ions, thereby significantly improving its adsorption selectivity for noble metal ions. Furthermore, this grafting reaction makes NH2-MIL-125(Ti)… The structural stability of the Ti material is enhanced, enabling it to better maintain its structure in complex noble metal-containing solution systems, making it less prone to collapse or degradation and ensuring the continuous and stable adsorption process. Furthermore, the imidazole-modified NH2-MIL-125(Ti) material undergoes a coordination reaction with bromoalkane to further functionalize the material. The introduction of bromide ions alters the electron cloud distribution on the material surface, resulting in a stronger electrostatic attraction to noble metal ions. Simultaneously, bromide ions can undergo ion exchange with the noble metal ions to be adsorbed, further increasing the adsorption capacity and adsorption rate of noble metal ions.

[0010] The functionalized material prepared by the above method not only retains the large specific surface area and regular pore structure of NH2-MIL-125(Ti), providing more adsorption space for noble metal ion adsorption, enabling the material to load a large number of noble metal ions, but also its regular pore structure facilitates the diffusion and transport of noble metal ions within the material, accelerating the adsorption rate. Furthermore, the grafted imidazole groups and bromide ions, as active sites, can coordinate or exchange with noble metal ions, thereby enhancing the material's adsorption capacity for noble metals. After adsorption, the material is placed under light, where the imidazole groups promote the transfer and separation of electrons in the NH2-MIL-125(Ti) material, causing the adsorbed noble metal ions to be reduced and generate elemental noble metals.

[0011] Furthermore, in steps a and b, the organic solvent is toluene.

[0012] Further, in step a, the organic base catalyst is 1,8-diazabicycloundec-7-ene.

[0013] The preferred catalyst can promote the grafting reaction of NH2-MIL-125(Ti) and N,N-carbonyldiimidazole, and increase the grafting rate of imidazole groups.

[0014] It should be noted that in step a, the organic base catalyst is slowly added to the reaction system, and after addition, it is stirred at room temperature in a sealed manner for 1.0 h to 1.5 h to fully activate the amino groups in NH2-MIL-125(Ti) and promote the reaction between the amino and imidazole groups.

[0015] Furthermore, in step b, the bromoalkane is bromobutane.

[0016] Further, in step a, the mass-to-volume ratio of NH2-MIL-125(Ti) to the organic solvent is (1.0-1.5) g : (20-30) mL.

[0017] Further, in step a, the amount of the organic base catalyst added is 0.2% to 0.4% of the mass of NH2-MIL-125(Ti).

[0018] Further, in step a, the amount of N,N-carbonyldiimidazole added is 0.02% to 0.04% of the mass of NH2-MIL-125(Ti).

[0019] Furthermore, in step a, the grafting reaction temperature is 20℃~40℃, and the grafting reaction time is 12h~15h.

[0020] Further, in step b, the mass-to-volume ratio of the imidazole-modified NH2-MIL-125(Ti) material to the organic solvent is (1-1.5) g:(20-30) mL.

[0021] Further, in step b, the mass ratio of the bromoalkane to the imidazole-modified NH2-MIL-125(Ti) material is (1-1.5):(0.25-0.5).

[0022] Furthermore, in step b, the temperature of the coordination reaction is 60℃~70℃, and the reaction time is 20h~24h.

[0023] It should be noted that the NH2-MIL-125(Ti) described in this invention can be a commercially available product or prepared using conventional methods in the art.

[0024] For example, the preparation method of NH2-MIL-125(Ti) includes the following steps:

[0025] 2-Aminoterephthalic acid was dissolved in a mixed solution of N,N-dimethylformamide and methanol, and isopropyl titanate was added. The mixture was stirred evenly and subjected to a hydrothermal reaction at 140℃~160℃ to obtain NH2-MIL-125(Ti).

[0026] Secondly, the present invention provides a functionalized NH2-MIL-125(Ti)-based material, which is prepared by the preparation method of the functionalized NH2-MIL-125(Ti)-based material described in any one of the above claims.

[0027] The functionalized NH2-MIL-125(Ti)-based material prepared by this invention possesses abundant active sites and a specific spatial structure, exhibiting a high adsorption rate and large adsorption capacity when adsorbing noble metals. In practical applications, even in solutions with low concentrations of noble metal ions, it can rapidly adsorb noble metal ions onto the material, and can adsorb large quantities of noble metal ions, thereby improving the efficiency and economic benefits of noble metal recovery.

[0028] Thirdly, the present invention provides the application of the above-mentioned functionalized NH2-MIL-125(Ti)-based material in the recycling of precious metals.

[0029] The functionalized NH2-MIL-125(Ti)-based material provided by this invention has many advantages in adsorbing and reducing precious metals, such as large adsorption capacity, high selectivity, fast adsorption rate, high reduction efficiency and structural stability, providing a highly promising solution for the recycling and reuse of precious metals.

[0030] Fourthly, the present invention provides a method for recycling precious metals, comprising the following steps:

[0031] The functionalized NH2-MIL-125(Ti)-based material was added to a solution containing the precious metal to be recovered for adsorption. After adsorption, solid-liquid separation was performed, and the separated solid was irradiated to obtain the recovered precious metal.

[0032] This invention utilizes a functionalized NH2-MIL-125(Ti)-based material for the adsorption and recovery of noble metals from solution. The adsorption process rapidly enriches the noble metal ions in the solution onto the material. After adsorption, light irradiation effectively reduces the adsorbed noble metal ions to elemental metals in situ, achieving highly efficient recovery. Furthermore, the Au(O) / functionalized NH2-MIL-125(Ti) composite material formed after in-situ reduction exhibits excellent catalytic activity and can be applied to various catalytic reactions, demonstrating significant research value and application potential in the field of catalysis. This invention not only achieves the recovery of expensive noble metals but also provides a high-performance catalyst for the catalysis field, meeting the requirements of green chemistry and sustainable development, and possessing high practical value. Attached Figure Description

[0033] Figure 1 The X-ray diffraction patterns of the products from each step in Example 1 are shown, where (a) NH2-MIL-125(Ti), (b) IM-NH2-MIL-125(Ti), and (c) IMOF catalyst.

[0034] Figure 2 The Fourier transform infrared spectra of the products from each step in Example 1 are shown below.

[0035] Figure 3 The images shown are scanning electron microscope images of the products from each step in Example 1, where (a) NH2-MIL-125(Ti), (b) IM-NH2-MIL-125(Ti), and (c) IMOF catalyst;

[0036] Figure 4 Micro-area elemental analysis chromatogram of the IMOFs catalyst prepared in Example 1;

[0037] Figure 5 This is a comparison chart of the adsorption effects of the products in each step of Example 1 on chloroauric acid ions;

[0038] Figure 6 The image shows a TEM image of the photocatalytic reduction of noble metals after the adsorption of IMOFs catalyst in Example 1; where (b) is a magnified view of the area circled in red in (a).

[0039] Figure 7 The images show the PXRD patterns of the IMOFs catalyst before and after the end of light irradiation in Example 1, when the adsorption of chloroaurate ions was completed. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] To better illustrate the present invention, further examples are provided below.

[0042] Example 1

[0043] This embodiment provides a method for preparing a functionalized NH2-MIL-125(Ti)-based material, comprising the following steps:

[0044] Step a: Measure 3 mL of methanol and 27 mL of N,N-dimethylformamide into a beaker and stir evenly with a magnetic stirrer. Weigh 0.408 g of 2-aminoterephthalic acid and add it into the beaker. Stir until completely dissolved. Then add 0.465 μL of isopropyl titanate and mix evenly. Transfer the mixed solution to a high-pressure reactor with a polytetrafluoroethylene liner and place it in a 150°C forced-air oven for 24 h. Remove and allow to cool naturally to room temperature. Centrifuge to separate the precipitate and wash with N,N-dimethylformamide until the supernatant is colorless. Then wash three times with methanol. Dry the obtained solid in a 60°C vacuum drying oven to constant weight to obtain NH2-MIL-125(Ti).

[0045] Step b: Measure 20 mL of toluene and add it to a beaker. Weigh 1.0 g of the NH2-MIL-125(Ti) powder prepared above and add it to the beaker. Mix well. Then weigh 3 mg of 1,8-diazabicycloundec-7-ene and slowly add it to the beaker. Seal and stir at room temperature for 1.0 h. Then add 0.357 mg of N,N-carbonyldiimidazole and stir at room temperature for 12 h. Centrifuge to separate the solid. Wash the obtained solid with toluene until the supernatant is colorless. Dry it in a vacuum drying oven at 60 °C for 24 h to obtain NH2-MIL-125(Ti) grafted with imidazole group, denoted as IM-NH2-MIL-125(Ti).

[0046] Step c: Measure 20 mL of toluene and add it to a beaker. Weigh 1.2 g of the IM-NH2-MIL-125(Ti) powder prepared above and add it to the beaker. Stir well and slowly add 282 μL of 1-bromobutane. Stir at 0 °C for 1 h, then transfer to an oil bath at 70 °C and react for 24 h. After the reaction is complete, cool naturally to room temperature, centrifuge to separate the solid, wash with toluene until the supernatant is colorless, and dry in a vacuum drying oven at 60 °C for 12 h to obtain the functionalized NH2-MIL-125(Ti)-based material, denoted as IMOFs.

[0047] Characterization

[0048] Figure 1 The XRD patterns of the NH2-MIL-125(Ti), IM-NH2-MIL-125(Ti), and IMOFs samples prepared in steps a to c are shown, with the simulated XRD pattern of NH2-MIL-125(Ti) used as a reference. It can be observed from the figures that the characteristic diffraction peaks of the obtained pure NH2-MIL-125(Ti) show high agreement with the simulated XRD pattern of NH2-MIL-125(Ti), and are consistent with the XRD pattern positions reported in previous literature, proving the successful preparation of NH2-MIL-125(Ti). The figures also clearly show the increasing activity of the imidazole functional group and the Br-anion. -During the grafting process, the intensity of the characteristic diffraction peaks of the NH2-MIL-125(Ti) material gradually decreased, but the peak positions remained unchanged without any shift. This indicates that the crystal structure of the NH2-MIL-125(Ti) material did not change significantly during the modification process, which can be attributed to the grafting of imidazole functional groups occurring at the amino sites of the ligands.

[0049] Figure 2 FT-IR spectra of the NH2-MIL-125(Ti), IM-NH2-MIL-125(Ti), and IMOFs samples prepared in steps a to c. For the NH2-MIL-125(Ti) material, the spectrum appears at 3367 cm⁻¹. -1 and 3437cm -1 The peak at 1385 cm⁻¹ is attributed to the stretching vibrations of NH and OH, while the peak at 1385 cm⁻¹ is attributed to the stretching vibrations of NH and OH. -1 1435cm -1 and 1540cm -1 The peak at 1624 cm⁻¹ is mainly caused by the stretching vibration of aromatic C and the vibration of carboxyl CO in the organic ligand. -1 The peak at 400–800 cm⁻¹ is mainly caused by the amino functional groups in the organic ligands of the NH₂-MIL-125(Ti) material. -1 The broad peak in the band is caused by the vibration of Ti-O-Ti clusters in the NH2-MIL-125(Ti) material. A peak at 1624 cm⁻¹ was observed in both NH2-MIL-125 material and IMOF samples. -1 The characteristic peak disappears at this point, mainly because the grafting process occurs at the amino site, disrupting the original infrared characteristics of the amino functional group. Therefore, the imidazole alkylation process introduces the anion Br. - This process did not disrupt the nodes in the MOF materials, thus preserving their original unique framework structure. The imidazole functional groups contain many Lewis basic nitrogen atoms, which can act as coordination and guest interaction sites in the ionization modification of MOF materials. FT-IR results show that imidazole functional groups exist in the IMOF samples, and... Figure 1 The results from XRD were consistent.

[0050] Figure 3 SEM images of the NH2-MIL-125(Ti), IM-NH2-MIL-125(Ti), and IMOFs samples prepared in steps a to c. Figure 3 (a) is a SEM image of the NH2-MIL-125(Ti) sample in Example 1. The image shows that the sample exhibits a thick, disc-shaped three-dimensional structure with a smooth and uniform surface, an average diameter of approximately 700 nm, and an average thickness of approximately 200 nm. Figure 3As can be observed in (b) and (c), the diameter and thickness of the IM-NH2-MIL-125 and IMOFs samples did not change significantly, and the surface smoothness did not change.

[0051] Figure 4 The micro-area elemental quantitative analysis of the IMOFs sample prepared in this embodiment shows that the Br content is about 16%, indicating that the NH2-MIL-125(Ti) material was successfully grafted with imidazole functional groups and the imidazole alkylation process was realized.

[0052] Adsorption performance test

[0053] The NH2-MIL-125(Ti), IM-NH2-MIL-125(Ti), and IMOFs prepared in steps a to c were subjected to chloroaurate ion adsorption experiments. The specific steps are as follows:

[0054] Take 2 mL of 58.86 mM chloroauric acid solution, add water to prepare an aqueous solution with an initial concentration of 400 mg / L, measure 100 mL of this solution and place it in a photocatalytic beaker, weigh 20 mg of the above dried sample and slowly add it to the photocatalytic beaker, and stir at room temperature to carry out the adsorption test.

[0055] The entire adsorption experiment was conducted in the dark. Every 20 minutes, 4 mL of sample was transferred to a centrifuge tube and centrifuged twice. After centrifugation, the supernatant was taken to measure the absorbance of the chloroauric acid solution at 285 nm before and after adsorption. The results are as follows: Figure 5 As shown in the figure. The experimental results show that after 100 min of adsorption, the adsorption rate of chloroauric acid by NH2-MIL-125(Ti) is 79%, the adsorption rate of chloroauric acid by IM-NH2-MIL-125(Ti) is 82%, and the adsorption rate of chloroauric acid by IMOFs is 90.7%.

[0056] The sample, after the adsorption experiment was completed, was irradiated under a xenon lamp simulating sunlight for 6 hours. After the irradiation ended, the solid was separated by centrifugation, and the sample was washed with deionized water until the supernatant was clear. The sample was then dried in a vacuum drying oven to constant weight to obtain the reduced sample. The HRTEM image of this sample is shown below. Figure 6 As shown in the figure, the interplanar spacing of the sample is 0.234 nm, which corresponds to the interplanar spacing of the Au(111) crystal plane, proving that Au nanoparticles are clearly present inside the material.

[0057] Figure 7 The PXRD patterns of the IMOF catalyst before and after irradiation after adsorption of chloroauric acid are shown. The figures reveal two strong diffraction peaks at 38.2° and 44.6°, belonging to Au, corresponding to the (111) and (200) crystal planes of Au, respectively. This indicates that AuCl was reduced by imidazole and bromide ions.4- Ions form metallic Au nanoparticles. The characteristic peaks of Au in the sample were significantly enhanced after illumination, indicating the formation of more elemental gold under photocatalysis, thus confirming the material's ability to photocatalytically reduce gold ions.

[0058] The IMOFs prepared above were subjected to adsorption tests of chloropalladium ions. The specific steps are as follows:

[0059] Take 2 mL of 58.86 mM sodium chloropalladium solution and add water to prepare an aqueous solution with an initial concentration of 400 mg / L. Measure 100 mL of this solution and place it in a photocatalytic beaker. Weigh 20 mg of the above-mentioned dried IMOFs sample and slowly add it to the photocatalytic beaker. Stir at room temperature to carry out the adsorption test.

[0060] The entire adsorption experiment was conducted in the dark. Every 20 minutes, 4 mL of sample was transferred to a centrifuge tube and centrifuged twice. After centrifugation, the supernatant was collected to measure the absorbance of the sodium chloropalladium solution at 420 nm before and after adsorption. The results showed that after 100 minutes of adsorption, the adsorption rate of sodium chloropalladium by IMOFs was 81.7%.

[0061] Example 2

[0062] This embodiment provides a method for preparing a functionalized NH2-MIL-125(Ti)-based material, comprising the following steps:

[0063] Step a: Measure 4 mL of methanol and 26 mL of N,N-dimethylformamide into a beaker and stir evenly with a magnetic stirrer. Weigh 0.35 g of 2-aminoterephthalic acid and add it into the beaker. Stir until completely dissolved. Then add 0.465 μL of isopropyl titanate and mix evenly. Transfer the mixed solution to a high-pressure reactor with a polytetrafluoroethylene liner and place it in a 150°C forced-air oven for 24 h. Remove and allow to cool naturally to room temperature. Centrifuge to separate the precipitate and wash with N,N-dimethylformamide until the supernatant is colorless. Then wash three times with methanol. Dry the obtained solid in a 60°C vacuum drying oven to constant weight to obtain NH2-MIL-125(Ti).

[0064] Step b: Measure 25 mL of toluene and add it to a beaker. Weigh 1.2 g of the NH2-MIL-125(Ti) powder prepared above and add it to the beaker. Mix well. Then weigh 4.8 mg of 1,8-diazabicycloundec-7-ene and slowly add it to the beaker. Seal and stir at room temperature for 1.0 h. Then add 0.24 mg of N,N-carbonyldiimidazole and stir at room temperature for 15 h. Centrifuge to separate the solid. Wash the obtained solid with toluene until the supernatant is colorless. Dry it in a vacuum drying oven at 60 °C for 24 h to obtain NH2-MIL-125(Ti) grafted with imidazole group, denoted as IM-NH2-MIL-125(Ti).

[0065] Step c: Measure 20 mL of toluene and add it to a beaker. Weigh 1 g of the IM-NH2-MIL-125(Ti) powder prepared above and add it to the beaker. Stir evenly and slowly add 300 μL of 1-bromobutane. Stir at 0 °C for 1 h, then transfer to an oil bath at 60 °C and react for 24 h. After the reaction is complete, cool naturally to room temperature, centrifuge to separate the solid, wash with toluene until the supernatant is colorless, and dry in a vacuum drying oven at 60 °C for 12 h to obtain the functionalized NH2-MIL-125(Ti)-based material, denoted as IMOFs.

[0066] The NH2-MIL-125(Ti), IM-NH2-MIL-125(Ti), and IMOFs prepared in steps a to c were subjected to chloroaurate ion adsorption experiments. The specific steps are as follows:

[0067] Take 2 mL of 58.86 mM chloroauric acid solution, add water to prepare an aqueous solution with an initial concentration of 400 mg / L, measure 100 mL of this solution and place it in a photocatalytic beaker, weigh 20 mg of the above dried sample and slowly add it to the photocatalytic beaker, and stir at room temperature to carry out the adsorption test.

[0068] The entire adsorption experiment was conducted in the dark. Every 20 minutes, 4 mL of sample was transferred to a centrifuge tube and centrifuged twice. After centrifugation, the supernatant was taken to measure the absorbance of the chloroauric acid solution at 285 nm before and after adsorption. The results are as follows: Figure 5 As shown in the figure. The experimental results show that after 100 min of adsorption, the adsorption rate of chloroauric acid by NH2-MIL-125(Ti) is 79%, the adsorption rate of chloroauric acid by IM-NH2-MIL-125(Ti) is 82%, and the adsorption rate of chloroauric acid by IMOFs is 90.3%.

[0069] Example 3

[0070] This embodiment provides a method for preparing a functionalized NH2-MIL-125(Ti)-based material, comprising the following steps:

[0071] Step a: Measure 3 mL of methanol and 30 mL of N,N-dimethylformamide into a beaker and stir evenly with a magnetic stirrer. Weigh 0.38 g of 2-aminoterephthalic acid and add it into the beaker. Stir until completely dissolved. Then add 0.465 μL of isopropyl titanate and mix evenly. Transfer the mixed solution to a high-pressure reactor with a polytetrafluoroethylene liner and place it in a 150°C forced-air oven for 24 h. Remove and allow to cool naturally to room temperature. Centrifuge to separate the precipitate and wash with N,N-dimethylformamide until the supernatant is colorless. Then wash three times with methanol. Dry the obtained solid in a 60°C vacuum drying oven to constant weight to obtain NH2-MIL-125(Ti).

[0072] Step b: Measure 30 mL of toluene and add it to a beaker. Weigh 1.5 g of the NH2-MIL-125(Ti) powder prepared above and add it to the beaker. Mix well. Then weigh 3 mg of 1,8-diazabicycloundec-7-ene and slowly add it to the beaker. Seal and stir at room temperature for 1.0 h. Then add 0.6 mg of N,N-carbonyldiimidazole and stir at room temperature for 13 h. Centrifuge to separate the solid. Wash the obtained solid with toluene until the supernatant is colorless. Dry it in a vacuum drying oven at 60 °C for 24 h to obtain NH2-MIL-125(Ti) grafted with imidazole group, denoted as IM-NH2-MIL-125(Ti).

[0073] Step c: Measure 30 mL of toluene and add it to a beaker. Weigh 1.5 g of the IM-NH2-MIL-125(Ti) powder prepared above and add it to the beaker. Stir evenly and slowly add 400 μL of 1-bromobutane. Stir at 0 °C for 1 h, then transfer to an oil bath at 70 °C and react for 20 h. After the reaction is complete, cool naturally to room temperature, centrifuge to separate the solid, wash with toluene until the supernatant is colorless, and dry in a vacuum drying oven at 60 °C for 12 h to obtain the functionalized NH2-MIL-125(Ti)-based material, denoted as IMOFs.

[0074] The NH2-MIL-125(Ti), IM-NH2-MIL-125(Ti), and IMOFs prepared in steps a to c were subjected to chloroaurate ion adsorption experiments. The specific steps are as follows:

[0075] Take 2 mL of 58.86 mM chloroauric acid solution, add water to prepare an aqueous solution with an initial concentration of 400 mg / L, measure 100 mL of this solution and place it in a photocatalytic beaker, weigh 20 mg of the above dried sample and slowly add it to the photocatalytic beaker, and stir at room temperature to carry out the adsorption test.

[0076] The entire adsorption experiment was conducted in the dark. Every 20 minutes, 4 mL of sample was transferred to a centrifuge tube and centrifuged twice. After centrifugation, the supernatant was taken to measure the absorbance of the chloroauric acid solution at 285 nm before and after adsorption. The results are as follows: Figure 5 As shown in the figure. The experimental results show that after 100 min of adsorption, the adsorption rate of chloroauric acid by NH2-MIL-125(Ti) is 79%, the adsorption rate of chloroauric acid by IM-NH2-MIL-125(Ti) is 82%, and the adsorption rate of chloroauric acid by IMOFs is 90.5%.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The application of a functionalized NH2-MIL-125(Ti)-based material in the recycling of precious metals, characterized in that, The preparation method of the functionalized NH2-MIL-125(Ti)-based material includes the following steps: Step a: Disperse NH2-MIL-125(Ti) in an organic solvent, add an organic base catalyst and N,N-carbonyldiimidazole, and carry out a grafting reaction to obtain imidazole-modified NH2-MIL-125(Ti) material; Step b: Disperse the imidazole-modified NH2-MIL-125(Ti) material in an organic solvent, add bromoalkane, and carry out a coordination reaction to obtain the functionalized NH2-MIL-125(Ti)-based material.

2. The application as described in claim 1, characterized in that, In steps a and b, the organic solvent is toluene; and / or In step a, the organic base catalyst is 1,8-diazabicycloundec-7-ene; and / or In step b, the bromoalkane is bromobutane.

3. The application as described in claim 1, characterized in that, In step a, the mass-to-volume ratio of NH2-MIL-125(Ti) to the organic solvent is (1.0~1.5) g : (20~30) mL; and / or In step a, the amount of the organic base catalyst added is 0.2% to 0.4% of the mass of NH2-MIL-125(Ti); and / or; In step a, the amount of N,N-carbonyldiimidazole added is 0.02% to 0.04% of the mass of NH2-MIL-125(Ti).

4. The application as described in claim 1, characterized in that, In step a, the grafting reaction temperature is 20℃~40℃, and the grafting reaction time is 12h~15h.

5. The application as described in claim 1, characterized in that, In step b, the mass-to-volume ratio of the imidazole-modified NH2-MIL-125(Ti) material to the organic solvent is (1~1.5) g:(20~30) mL; and / or In step b, the mass ratio of the bromoalkane to the imidazole-modified NH2-MIL-125(Ti) material is (1~1.5):(0.25~0.5).

6. The application as described in claim 1, characterized in that, In step b, the temperature of the coordination reaction is 60℃~70℃, and the reaction time is 20h~24h.

7. The application as described in claim 1, characterized in that, The preparation method of the NH2-MIL-125(Ti) includes the following steps: Dissolve 2-aminoterephthalic acid in a mixed solution of N,N-dimethylformamide and methanol, add isopropyl titanate, mix well, and carry out a hydrothermal reaction at 140℃~160℃ to obtain NH2-MIL-125(Ti).

8. A method for recycling precious metals, characterized in that, Includes the following steps: The functionalized NH2-MIL-125(Ti)-based material as described in any one of claims 1 to 7 is added to a solution containing the precious metal to be recovered for adsorption. After adsorption, solid-liquid separation is performed, and the separated solid is irradiated to obtain the recovered precious metal.

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