A hydroxyl-rich metal-organic framework material, a preparation method and application thereof
By modifying UiO-66-(OH)2 material, a hydroxyl-rich metal-organic framework material UiO-66-(OH)2-X was prepared, which solved the problem of insufficient adsorption capacity, achieved efficient adsorption and separation and selective adsorption of lead ions, reduced costs and improved economic benefits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2025-06-18
- Publication Date
- 2026-06-16
AI Technical Summary
The existing UiO-66-(OH)2 metal-organic framework material has a limited effective adsorption capacity, resulting in high usage costs and hindering its widespread application.
By introducing the substituted ligand 2,3-dihydroxyterephthalic acid to modify UiO-66-(OH)2, a hydroxyl-rich metal-organic framework material UiO-66-(OH)2-X was prepared, which enhanced its binding sites and negative charge, thereby improving its adsorption capacity and selectivity for Pb2+.
It achieves efficient and selective adsorption and separation of lead ions, reduces processing costs, improves economic benefits, and maintains good adsorption performance in complex ionic systems.
Smart Images
Figure CN120737356B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of metal-organic framework materials technology, specifically relating to a hydroxyl-rich metal-organic framework material, its preparation method, and its application. Background Technology
[0002] Lead (Pb) is a corrosion-resistant heavy non-ferrous metal widely used in batteries, radiation protection, and cables. However, lead in industrial wastewater is considered one of the most toxic pollutants harmful to human health. Lead poisoning can damage the nervous system, circulatory system, and various organs, and in severe cases, it can be life-threatening. Therefore, effective wastewater treatment technologies are of great value and significance for protecting the environment and human health.
[0003] Currently, there are various methods for treating lead-containing wastewater, including chemical deposition, membrane separation, biological treatment, and adsorption. Among them, adsorption is a method that uses physical or chemical action on the surface of an adsorbent to adsorb target ions or molecules in the solution onto the surface of the adsorbent. Adsorption is simple to operate, has low energy consumption, good selectivity, and treatment efficiency, so it has a good application in water treatment.
[0004] Metal-organic frameworks (MOFs) are porous materials with highly tunable pore structures and chemical properties. Compared to other porous materials, MOFs are diverse, have large specific surface areas, and are highly modifiable, exhibiting excellent adsorption capacity and selectivity for target adsorbates, making them high-performance adsorbents. MOFs are frequently used for the adsorption of metal ions due to their abundant binding sites and charged properties. They can be modified with specific functional groups (such as sulfonic acid groups, mercapto groups, amino groups, carboxyl groups, and hydroxyl groups) to achieve highly efficient and selective adsorption of lead ions through electrostatic interactions, chelation effects, and interactions between hard and soft acids and bases. In existing technologies, UiO-66-(OH)2 MOFs are commonly used for the adsorption of lead ions (Pb). 2+ Adsorption separation is used, but its effective adsorption capacity is limited, resulting in high usage costs and hindering its widespread application. Summary of the Invention
[0005] The main objective of this invention is to overcome the shortcomings of existing technologies and solve the technical problem of insufficient effective adsorption performance of existing adsorbent materials. This invention provides a hydroxyl-rich metal-organic framework material, its preparation method, and its application. By utilizing a metal-organic framework material with abundant negative charge and local hydroxyl density as an adsorbent, highly efficient and selective separation and purification of lead from plasma-based solutions containing potassium, calcium, magnesium, cobalt, copper, chloride ions, and nitrate ions is achieved, saving manpower and resources and improving economic efficiency.
[0006] This invention is achieved through the following technical solution: a hydroxyl-rich metal-organic framework material, wherein: the chemical structural formula of the hydroxyl-rich metal-organic framework material is Zr6O4(OH)4[BDC-(OH)2]6, named UiO-66-(OH)2-X, where X represents a ligand, the ligand includes a protoligand and a substituted ligand for replacing the protoligand, the protoligand and the substituted ligand have the same molecular formula but different structures, the protoligand is 2,5-dihydroxyterephthalic acid, the substituted ligand is 2,3-dihydroxyterephthalic acid, and the molar ratio of the protoligand to the substituted ligand is (3~5):1. This invention modifies UiO-66-(OH)2 by replacing part of the protoligand with the substituted ligand to obtain a metal-organic framework material with stronger electronegativity and efficient coupling utilization of binding sites, utilizing its electronegativity and the synergistic effect of the binding sites to capture more Pb. 2+ Ions. Compared to traditional materials, the binding site distribution of the hydroxyl-rich metal-organic framework material provided by this invention is greatly improved.
[0007] Furthermore, the zeta potential of hydroxyl-rich metal-organic framework materials is negative in the pH range of 3 to 10, exhibiting stronger negative charge compared to traditional materials.
[0008] The preparation method of the hydroxyl-rich metal-organic framework material as described above includes the following steps:
[0009] S1. Weigh the raw materials: Weigh ZrOCl2·8H2O, the original ligand, the substituted ligand, acetic acid and deionized water respectively; wherein, ZrOCl2·8H2O is used as the metal source, the molar ratio of ZrOCl2·8H2O to the ligand is 1:1, and the volume ratio of deionized water to acetic acid is 1:1.
[0010] S2. Add the raw materials weighed in step S1 to a round-bottom flask, stir evenly, and then heat in an oil bath to carry out in-situ synthesis reaction. The heating temperature is 368K and the in-situ synthesis reaction time is 3h.
[0011] S3. After the in-situ synthesis reaction is completed, the mixture is cooled to room temperature, filtered, and the precipitate (yellowish-brown solid) is collected. The precipitate is washed repeatedly with deionized water and methanol at least three times. Finally, the collected material is centrifuged and dried at 373 K for 12 h to obtain a hydroxyl-rich metal-organic framework material (yellowish-brown solid powder).
[0012] As described above, hydroxyl-rich metal-organic framework materials are used as adsorbents for Pb. 2+ The adsorbent, i.e., the one containing only Pb 2+ solutions or solutions containing Pb 2+ Adsorption separation of Pb in binary solution 2+ .
[0013] Furthermore, the Pb-containing 2+ The binary solution contains Pb 2+ In addition, it also contains Cu 2+ Mg 2+ Ca 2+ Co 2+ K + NO3 - Or Cl - Any one of them.
[0014] Furthermore, the adsorption and separation steps of the hydroxyl-rich metal-organic framework material are as follows: weigh 5 mg of zirconium-based metal-organic framework material and add it to Pb. 2+ In the solution, adsorption separation was carried out on a constant-temperature shaker for 12 hours; the Pb 2+ The solution has a pH of 5, a concentration of 100~500 mg / L, and a volume of 10 mL; the constant temperature shaker rotates at 155 rpm and is at a temperature of 303 K.
[0015] Furthermore, in hydroxyl-rich metal-organic framework materials, the molar ratio of the original ligand to the substituted ligand is 3:1, which enhances the effect of hydroxyl-rich metal-organic framework materials on Pb. 2+ Pb in solution 2+ The adsorption capacity was 404.8 mg / g.
[0016] The beneficial effects of this invention are as follows:
[0017] 1. This invention modifies UiO-66-(OH)2 in situ by introducing the substituted ligand 2,3-dihydroxyterephthalic acid, thereby improving the binding site distribution and charge characteristics of the original metal-organic framework material. Through the negative charge and effective combined effect of the two hydroxyl groups, the adsorption capacity and selectivity of the metal-organic framework material for lead ions are improved.
[0018] 2. Using the metal-organic framework material prepared in this invention as an adsorbent, the selective adsorption separation method can significantly promote the purification of lead in aqueous solution, and the operation is simple and convenient. Attached Figure Description
[0019] Figure 1 The XRD patterns are shown in Comparative Example 1 and Examples 1 and 2.
[0020] Figure 2 The images show a comparison of scanning electron microscope (SEM) images of the three metal-organic framework materials in Comparative Example 1 and Examples 1 and 2.
[0021] Figure 3 This is a comparison chart of the nitrogen adsorption-desorption performance of Comparative Example 1 and Examples 1 and 2;
[0022] Figure 4 This is a comparison chart of the pore size distribution curves of Comparative Example 1 and Examples 1 and 2;
[0023] Figure 5 This is a comparison of the zeta potential curves of the three metal-organic framework materials in Comparative Example 1 and Examples 1 and 2 in the pH range of 2.0 to 10.0.
[0024] Figure 6 Comparison of the nuclear magnetic resonance spectra of the two metal-organic framework materials and the two pure ligands prepared in Examples 1 and 2;
[0025] Figure 7 This is a comparison chart showing the adsorption performance of lead ions by the three metal-organic framework materials in Comparative Example 1 and Examples 1 and 2.
[0026] Figure 8 The three metal-organic framework materials in Example 2 are for Pb-containing... 2+ Adsorption and separation performance diagram of binary solution;
[0027] Figure 9 The graph shows the adsorption and separation performance of the three metal-organic framework materials in Example 2 for solutions containing lead ions and potassium / magnesium ions with specific mass concentration ratios.
[0028] Figure 10 The metal-organic framework materials and Pb in Comparative Example 1 and Example 2 2+ A comparison diagram of the bonding modes and their corresponding binding energies; in the diagram, a represents the bonding between the hydroxyl groups and Pb in the UiO-66-(OH)2 material. 2+ The bonding mode and corresponding bonding energy; b~d represent the bonding between hydroxyl groups and Pb in the UiO-66-(OH)2-X material. 2+ The binding mode and the corresponding binding energy. Detailed Implementation
[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0030] The chemical reagents used in the following comparative examples and embodiments are zirconium oxychloride octahydrate, 2,5-dihydroxyterephthalic acid, 2,3-dihydroxyterephthalic acid, acetic acid, lead nitrate, potassium nitrate, calcium nitrate, magnesium nitrate, etc. Among them, zirconium oxychloride octahydrate and 2,5-dihydroxyterephthalic acid were purchased from Beijing Huawi Ruike Chemical Co., Ltd., 2,3-dihydroxyterephthalic acid was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and lead nitrate was purchased from Shandong Xiya Chemical Co., Ltd.
[0031] It should also be noted that:
[0032] The powder X-ray diffraction test conditions were: Cu-Kα radiation, D8 Advance X-ray diffractometer, room temperature, 2θ range of 3°~50°, step size of 0.02°;
[0033] Morphology analysis: SU8020 field emission scanning electron microscope;
[0034] Nitrogen adsorption-desorption curves and pore size distribution tests: Adsorption capacity calculation formula: Autosorb-iQ-MP surface area analyzer, 77K;
[0035] Zeta potential testing conditions: Malvern Nano ZS90 potential analyzer, pH range 2.0~10.0;
[0036] 13 C10 NMR spectroscopy: JNM-ECZ400S / L1 spectrometer, dissolving solvents were 0.5 mL sulfuric acid and 0.6 mL DMSO- d 6; Metal ion concentration determination: Avio 200 inductively coupled plasma atomic emission spectrometer;
[0037] Binding energy calculation: First-principles calculation, software CP2K.
[0038] Comparative Example 1
[0039] The in-situ synthesis of UiO-66-(OH)2 metal-organic framework materials via a solvothermal method includes the following steps:
[0040] S1. Weigh the raw materials: Weigh 1.289g ZrOCl2·8H2O, 0.7925g 2,5-dihydroxyterephthalic acid, 10mL deionized water and 10mL acetic acid respectively;
[0041] S2. Add the raw materials weighed in step S1 to a 50 mL round-bottom flask, stir well, and then heat in an oil bath to carry out the in-situ synthesis reaction at a temperature of 368 K for 3 h.
[0042] S3. After the in-situ synthesis reaction is completed, the mixture is cooled to room temperature, filtered, and the precipitate is collected. The precipitate is washed repeatedly with deionized water and methanol at least three times. Finally, the collected material is centrifuged and dried at a temperature of 373 K for 12 h to obtain the UiO-66-(OH)2 metal-organic framework material.
[0043] 1. Characterization of UiO-66-(OH)2 material:
[0044] Figure 1The powder XRD pattern of UiO-66-(OH)2 material is shown in the figure. Its characteristic peaks are basically consistent with the simulated standard spectrum, indicating that the material was successfully prepared.
[0045] Figure 2 The image shows that the UiO-66-(OH)2 material particles obtained by scanning electron microscopy have a polyhedral morphology and an average particle size of 300 nm.
[0046] Figure 3 The nitrogen adsorption-desorption performance curves of the UiO-66-(OH)2 material are shown, revealing a specific surface area of 1047.8 m². 2 / g, pore volume is 0.4336cm³ 3 / g;
[0047] Figure 4 The figure shows the pore size distribution curve of UiO-66-(OH)2 material. The pore size distribution of UiO-66-(OH)2 material is between 0.4 and 0.8 nm, which is a microporous material.
[0048] Figure 5 The figure shows the zeta potential curve of UiO-66-(OH)2 material, indicating that the potential value of UiO-66-(OH)2 material is 23~0mV in the pH range of 2.0~3.5, which is positively charged; and the potential value is 0~-32mV in the pH range of 3.5~10.0, which is negatively charged.
[0049] 2. Application of UiO-66-(OH)2 material: UiO-66-(OH)2 material can be used to extract Pb from solution. 2+ Specifically, the steps include: adding 5 mg of UiO-66-(OH)2 material to 10 mL of Pb-only material. 2+ The solution contains only Pb 2+ The initial ion concentration of the solution was 500 mg / L. Adsorption was carried out at 303 K and 155 rpm for 12 h. After filtration, the solid material was collected. The supernatant was collected, and the content of remaining metal ions was determined.
[0050] like Figure 7 As shown, the adsorption capacity of UiO-66-(OH)2 material was calculated based on the adsorption capacity calculation formula when it contained only Pb. 2+ The solution (initial ion concentration of 500 mg / L) for Pb 2+ The adsorption capacity was 67.6 mg / g.
[0051] Figure 10 In the material UiO-66-(OH)2, hydroxyl group and Pb are present. 2+ The binding mode and binding energy indicate that the free hydroxyl group in the ligand binds to Pb.2+ It has a certain binding effect. Example 1
[0052] A method for preparing a hydroxyl-rich metal-organic framework material (named: UiO-66-(OH)2-A) includes the following steps:
[0053] S1. Weigh the raw materials: Weigh 1.289g ZrOCl2·8H2O, 0.6604g 2,5-dihydroxyterephthalic acid, 0.1321g 2,3-dihydroxyterephthalic acid, 10mL acetic acid, and 10mL deionized water respectively.
[0054] S2. Add the raw materials weighed in step S1 to a 50 mL round-bottom flask, stir well, and then heat in an oil bath to carry out the in-situ synthesis reaction at a temperature of 368 K for 3 h.
[0055] S3. After the in-situ synthesis reaction is completed, the mixture is cooled to room temperature, filtered, and the precipitate is collected. The precipitate is washed repeatedly with deionized water and methanol at least 3 times. Finally, the collected material is centrifuged and dried at a temperature of 373K for 12 hours to obtain the hydroxyl-rich metal-organic framework material UiO-66-(OH)2-A.
[0056] 1. Characterization of UiO-66-(OH)2-A material:
[0057] Figure 1 The powder XRD pattern of UiO-66-(OH)2-A material is shown in the figure. Its characteristic peaks are basically consistent with the pattern of Example 1, indicating that the material was successfully prepared.
[0058] Figure 2 The image shows that the UiO-66-(OH)2-A material particles obtained by scanning electron microscopy are spherical with an average particle size of 300 nm.
[0059] Figure 3 The nitrogen adsorption-desorption performance curves of the UiO-66-(OH)2-A material are shown, revealing a specific surface area of 904.8 m². 2 / g, pore volume is 0.5346cm³ 3 / g;
[0060] Figure 4 The figure shows the pore size distribution curve of UiO-66-(OH)2-A material. The pore size distribution of UiO-66-(OH)2-A material is between 0.4 and 0.75 nm, which is a microporous material.
[0061] Figure 5The zeta potential curves of the UiO-66-(OH)2-A material are shown. The potential value of UiO-66-(OH)2-A material is 8~0mV in the pH range of 2.0~2.5, indicating a positive charge; and the potential value is 0~-40mV in the pH range of 2.5~10.0, indicating a negative charge. Compared with Comparative Example 1, the negative charge is stronger.
[0062] Figure 6 The NMR spectra of UiO-66-(OH)2-A material and its two ligands show that Example 1 contains both the spectral peaks of the original ligand 2,5-dihydroxyterephthalic acid at the hydrogen position and the spectral peaks of the substituted ligand 2,3-dihydroxyterephthalic acid at the hydrogen position.
[0063] 2. Application of UiO-66-(OH)2-A material: The UiO-66-(OH)2-A material prepared in Example 1 can be used for Pb in solution. 2+ Extraction. The specific method is as follows: Weigh 5 mg of UiO-66-(OH)2-A and add it to 10 mL of Pb-containing solution. 2+ The solution contains only Pb 2+ The initial ion concentration of the solution was 500 mg / L. Adsorption was carried out at 303 K and 155 rpm for 12 h. After filtration, the supernatant was collected and the content of the remaining metal ions was determined.
[0064] like Figure 7 As shown, the adsorption capacity of UiO-66-(OH)2-A material was calculated according to the adsorption capacity calculation formula when it contained only Pb. 2+ The solution (initial ion concentration of 500 mg / L) for Pb 2+ The adsorption capacity was 84.1 mg / g. Compared with Comparative Example 1, the coupling effect of hydroxyl groups on lead in some pores of the UiO-66-(OH)2-A material was enhanced due to the presence of a small amount of ortho-hydroxyl groups in the ligand, thus improving the adsorption performance. Example 2
[0065] A method for preparing a hydroxyl-rich metal-organic framework material (named: UiO-66-(OH)2-B) includes the following steps:
[0066] S1. Weigh the raw materials: Weigh 1.289g ZrOCl2·8H2O, 0.5944g 2,5-dihydroxyterephthalic acid, 0.1981g 2,3-dihydroxyterephthalic acid, 10mL acetic acid, and 10mL deionized water respectively.
[0067] S2. Add the raw materials weighed in step S1 to a 50 mL round-bottom flask, stir well, and then heat in an oil bath to carry out the in-situ synthesis reaction at a temperature of 368 K for 3 h.
[0068] S3. After the in-situ synthesis reaction was completed, the mixture was cooled to room temperature, filtered, and the precipitate was collected. The precipitate was washed repeatedly with deionized water and methanol at least three times. The final product was centrifuged and dried at 373 K for 12 hours to obtain the hydroxyl-rich metal-organic framework material UiO-66-(OH)2-B. It should be noted that both UiO-66-(OH)2-A and UiO-66-(OH)2-B belong to UiO-66-(OH)2-X; they are simply designated as "-A" and "-B" to distinguish the different proportions of the protons (original and substituted ligands).
[0069] 1) Characterization of UiO-66-(OH)2-B material:
[0070] Figure 1 The powder XRD pattern of UiO-66-(OH)2-B material is shown in the figure. The characteristic peaks are basically consistent with the pattern of Example 2, indicating that the material was successfully prepared.
[0071] Figure 2 The image shows that the UiO-66-(OH)2-B material particles obtained by scanning electron microscopy are spherical with an average particle size of 700 nm, which is larger than the particles in Comparative Example 1 and Example 1.
[0072] Figure 3 The nitrogen adsorption-desorption performance curves of UiO-66-(OH)2-B material are shown, revealing a specific surface area of 449.8 m². 2 / g, pore volume is 0.2583cm³ 3 / g;
[0073] Figure 4 The figure shows the pore size distribution curve of UiO-66-(OH)2-B material. The pore size distribution of UiO-66-(OH)2-B material is between 0.4 and 0.75 nm, which is a microporous material.
[0074] Figure 5 The image shows the zeta potential curve of the UiO-66-(OH)2-B material. The surface potential of the UiO-66-(OH)2-B material is -3 to -33 mV at pH = 2.0 to 10.0, indicating that it is negatively charged.
[0075] Figure 6 The NMR spectra of UiO-66-(OH)2-B material and two ligands are shown in the figure. It can be seen that Example 2 contains both the spectral peaks of the hydrogen positions in the original ligand and the spectral peaks of the hydrogen positions in the substituted ligand.
[0076] 2. Application of UiO-66-(OH)2-B material: The UiO-66-(OH)2-B material prepared in Example 2 can be used in Pb-containing materials. 2+ Pb adsorption separation in solution 2+ The specific method is as follows: Weigh 5 mg of UiO-66-(OH)2-B and add it to 10 mL of Pb-containing... 2+ The solution was adsorbed for 12 h at a temperature of 303 K and a rotation speed of 155 rpm. After filtration, the supernatant was collected and the content of the remaining metal ions was determined.
[0077] like Figure 7 As shown, when the initial ionic solution (concentration of 500 mg / L) contains only Pb 2+ The solution was analyzed using the adsorption capacity calculation formula, and the adsorption capacity of the UiO-66-(OH)2-B material in the presence of only Pb was calculated. 2+ Pb in solution 2+ The adsorption capacity was 404.8 mg / g.
[0078] like Figure 8 As shown, when the initial ionic solution (concentration of 100 mg / L) contains Pb 2+ binary solution (Pb) 2+ and K + Binary solutions, or Pb 2+ and Mg 2+ (binary solution), the adsorption capacity of UiO-66-(OH)2-B material on Pb was calculated according to the adsorption capacity calculation formula. 2+ The adsorption capacity was 66 mg / g, and the presence of other ions had little effect on its adsorption capacity.
[0079] like Figure 9 As shown, with Pb 2+ and K + K in a binary solution + The mass concentration of Pb increases, or Pb 2+ and Mg 2+ Mg in a binary solution 2+ With increasing mass concentration, the UiO-66-(OH)2-B material has a greater effect on Pb. 2+ The adsorption amount remains unchanged.
[0080] Combination Figure 8 and Figure 9 It can be seen that UiO-66-(OH)2-X has a strong anti-interference ability.
[0081] Figure 10 In the material UiO-66-(OH)2, hydroxyl group and Pb are present. 2+ The binding mode and binding energy indicate that the free hydroxyl group in the ligand binds to Pb. 2+ It has a certain binding effect.
[0082] Figure 10 In the material UiO-66-(OH)2-B, hydroxyl groups and Pb are present. 2+ Regarding the binding mode and binding energy, compared to Comparative Example 1, the hydroxyl groups on the same side of the UiO-66-(OH)2-B material may bind to a Pb group. 2+ The binding energy is stronger when they combine; it is also possible for them to combine with two Pb groups. 2+ The binding energy is stronger. Therefore, the adsorption performance of UiO-66-(OH)2-B material is greatly improved due to the combined effect of the ligand binding sites and the stronger negative charge.
[0083] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A hydroxyl-rich metal-organic framework material, characterized in that, The chemical structural formula of the hydroxyl-rich metal-organic framework material is Zr6O4(OH)4[BDC-(OH)2]6. The ligands include the original ligand and the substituted ligands used to replace the original ligand. The original ligand and the substituted ligand have the same molecular formula but different structures. The original ligand is 2,5-dihydroxyterephthalic acid, and the substituted ligand is 2,3-dihydroxyterephthalic acid. The molar ratio of the original ligand to the substituted ligand is (3~5):
1.
2. The hydroxyl-rich metal-organic framework material according to claim 1, characterized in that, Hydroxyl-rich metal-organic framework materials exhibit negative zeta potentials within a pH range of 3 to 10.
3. A method for preparing a hydroxyl-rich metal-organic framework material as described in claim 1, characterized in that, Includes the following steps: S1. Weigh the raw materials: Weigh ZrOCl2·8H2O, the original ligand, the substituted ligand, acetic acid and deionized water respectively; wherein, ZrOCl2·8H2O is used as the metal source, the molar ratio of ZrOCl2·8H2O to the ligand is 1:1, and the volume ratio of deionized water to acetic acid is 1:
1. S2. Add the raw materials weighed in step S1 to a round-bottom flask, stir evenly, and then heat in an oil bath to carry out in-situ synthesis reaction. The heating temperature is 368K and the in-situ synthesis reaction time is 3h. S3. After the in-situ synthesis reaction is completed, the mixture is cooled to room temperature, filtered, and the precipitate is collected. The precipitate is washed repeatedly with deionized water and methanol at least three times. Finally, the collected material is centrifuged and dried at 373K for 12 hours to obtain a hydroxyl-rich metal-organic framework material.
4. An application of the hydroxyl-rich metal-organic framework material as described in claim 1, characterized in that, The hydroxyl-rich metal-organic framework material is used as a Pb adsorption material. 2+ The adsorbent, i.e., the one containing only Pb 2+ solutions or solutions containing Pb 2+ Adsorption separation of Pb in binary solution 2+ .
5. The application according to claim 4, characterized in that, The Pb-containing 2+ The binary solution contains Pb 2+ In addition, it also contains Cu 2+ Mg 2+ Ca 2+ Co 2+ K + NO3 - Or Cl - Any one of them.
6. The application according to claim 4, characterized in that, The steps for adsorption and separation of hydroxyl-rich metal-organic framework materials are as follows: Weigh 5 mg of hydroxyl-rich metal-organic framework material and add it to Pb. 2+ In the solution, adsorption separation was carried out on a constant-temperature shaker for 12 hours; the Pb 2+ The solution has a pH of 5, a concentration of 100~500 mg / L, and a volume of 10 mL; the constant temperature shaker rotates at 155 rpm and is at a temperature of 303 K.
7. The application according to claim 6, characterized in that, In hydroxyl-rich metal-organic framework materials, the molar ratio of the original ligand to the substituted ligand is 3:
1. Hydroxyl-rich metal-organic framework materials are effective against Pb. 2+ Pb in solution 2+ The adsorption capacity was 404.8 mg / g.