Preparation method and application of a porous organic framework material

Abstract

The application belongs to the technical field of water purification, and particularly relates to a preparation method and application of a porous organic framework material. The preparation method comprises the following steps: S1. dissolving 1,3,6,8-tetra(1H-imidazole-1-yl)pyrene and 1,2,4,5-tetra(bromomethyl)benzene in an N,N-dimethylformamide organic solvent to obtain a mixed solution; S2. placing the mixed solution in a microwave reaction instrument for heating reaction, separating and washing the product, immersing the product in a saturated NaCl solution, separating and drying the product after the immersing, and obtaining the porous organic framework material CPN-M-1. The cationic polymer porous organic framework material prepared by the application has the advantages of high chemical stability, strong designability, easy functionalization modification and the like, is an effective material for treating radioactive anion pollutants, can specifically recognize and efficiently capture molybdate ions in a complex water environment, and can realize simultaneous separation of multiple radioactive anions.

Description

Technical Field

[0001] This invention belongs to the field of water purification technology, specifically relating to the preparation method and application of porous organic framework materials. Background Technology

[0002] Molybdenum is widely used in steel metallurgy, electronic devices, chemical catalysis, and agricultural production. With the continued active mining and processing of molybdenum resources, the discharge of molybdenum-containing wastewater has been increasing year by year, leading to increasingly serious water pollution problems. In particular, industrial wastewater generated during molybdenum mining, beneficiation, and metallurgical processes often causes molybdenum concentrations in surrounding water bodies to far exceed the 0.07 mg / L limit stipulated in the "Standards for Drinking Water Quality" and the "Surface Water Environmental Quality Standards," with molybdenum content in some mining areas even reaching as high as 10 mg / L.

[0003] In natural water bodies, molybdenum mainly exists as molybdate (MoO4). 2- It exists in the form of ) MoO4. Although trace amounts of molybdenum are essential trace elements for plants, animals, and humans, excessive amounts can have negative impacts on ecosystems and human health. When MoO4 is present in aqueous solution 2- Concentrations exceeding 5 ppm pose environmental hazards, and long-term exposure can lead to adverse reactions such as gastrointestinal disorders, protein metabolism disturbances, and connective tissue degeneration. Therefore, the efficient and selective adsorption and separation of MoO4 from environmental water bodies is crucial. 2- This is not only an urgent need to safeguard ecological environment security and human health, but also an important way to achieve sustainable utilization of molybdenum resources.

[0004] Currently, the main technologies for treating molybdenum-containing wastewater include ion exchange, chemical precipitation, extraction, and adsorption. While ion exchange and chemical precipitation have wide applications, they suffer from high costs, secondary pollution, and low removal efficiency for low concentrations of molybdenum. Extraction faces challenges such as solvent depletion and complex processes. Adsorption, on the other hand, has attracted considerable attention due to its ease of operation, relatively low cost, high efficiency, and ease of regeneration. However, existing adsorption materials still face many limitations, such as insufficient selectivity and susceptibility to SO4 in the wastewater. 2- Cl - NO3 - The current technology suffers from several drawbacks, including the influence of competing anions, slow adsorption kinetics that make it difficult to meet the needs of large-scale industrial wastewater treatment, and poor regeneration efficiency. Therefore, developing a novel, highly efficient adsorption material for treating molybdenum-containing wastewater can address these shortcomings to some extent. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention prepares a porous organic framework material with advantages such as high chemical stability, strong designability, and ease of functionalization. This material is an effective agent for treating radioactive anionic pollutants and can specifically identify and efficiently capture molybdate ions in complex aquatic environments. This invention provides a new approach and practical technology for the deep purification and resource recovery of molybdate ions in environmental water bodies.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The first aspect of this invention provides a method for preparing a porous organic framework material, comprising the following steps:

[0008] S1. Dissolve 1,3,6,8-tetrakis(1H-imidazol-1-yl)pyrene and 1,2,4,5-tetrakis(bromomethyl)benzene in N,N-dimethylformamide organic solvent to obtain a mixed solution; wherein the water content of N,N-dimethylformamide organic solvent is ≤0.1 wt%;

[0009] S2. The mixture was heated and reacted in a microwave reactor. After the product was separated and washed, it was soaked in a saturated NaCl solution. After soaking, the product was separated and dried to obtain the porous organic framework material CPN-M-1.

[0010] The chemical structural formula of the porous organic framework material CPN-M-1 is as follows:

[0011] .

[0012] The synthesis of this porous organic framework material is based on the Menshutkin reaction principle. It utilizes the reaction of a tertiary amine with a haloalkanes to generate a quaternary ammonium salt, forming a covalently bonded porous organic framework material (CPN-M-1), which is a cationic polymer porous organic framework material. The synthetic route is as follows: Figure 1 As shown, CPN-M-Br is Br replaced by unsaturated NaCl. - The product of this process, CPN-M-1, is a porous organic framework material.

[0013] In this invention, the organic solvent used in the synthesis reaction is selected from DMF. Increased water content significantly reduces the reaction yield of tertiary amines and haloalkanes to form quaternary ammonium salts. This is mainly because water directly competes with the tertiary amine for nucleophilic attack on the haloalkanes, leading to the hydrolysis of the haloalkanes into alcohols and the production of hydrogen halides (HX) as a byproduct. The generated HX then protonates the tertiary amine, converting it into a nucleophilically inactive ammonium salt, thereby drastically reducing the effective reactant concentration. Simultaneously, the strong solvation effect of a large amount of water hinders effective collisions between reactants and may promote the ion dissociation of the products. Therefore, this invention selects ultra-dry DMF with a water content ≤0.1 wt%.

[0014] In one specific embodiment, the 1,3,6,8-tetra(1H-imidazol-1-yl)pyrene and 1,2,4,5-tetra(bromomethyl)benzene are dissolved in a molar ratio of 1:1.

[0015] In one specific embodiment, the heating reaction conditions are: temperature 100 °C, reaction time 4 h.

[0016] In one specific embodiment, the washing is performed by sequentially washing with N,N-dimethylformamide, deionized water and anhydrous ethanol, wherein the water content of N,N-dimethylformamide is ≤0.1 wt%.

[0017] In one specific embodiment, the soaking time is 5-24 hours.

[0018] A second aspect of the present invention provides a porous organic framework material, obtained according to the preparation method described above.

[0019] A third aspect of the present invention provides a method for efficiently adsorbing and separating molybdate ions in water using the aforementioned porous organic framework material, comprising the following steps:

[0020] The porous organic framework material was added to a water body containing molybdate.

[0021] Adjust the pH value to the range of 2-10 and mix and stir. After filtration, measure the concentration of molybdate.

[0022] In one specific embodiment, the pH value is 3.

[0023] In one specific embodiment, the mixing and stirring time is 5 minutes.

[0024] The fourth aspect of the present invention provides an application of the porous organic framework material described above in the efficient adsorption and separation of molybdate ions in environmental water.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0026] 1. The porous organic framework material prepared by this invention has been verified to have a stable molybdate removal rate within a pH range of 2-10, with a removal rate of over 91% for molybdate ions. Furthermore, the adsorption rate is extremely fast, reaching adsorption equilibrium within just 5 minutes. For solutions containing low concentrations of molybdate ions, it can achieve deep removal of molybdate with a removal rate as high as 99.98%. It also exhibits high saturated adsorption capacity, reaching its maximum at pH=3, at 522.02 mg / g.

[0027] 2. The porous organic framework material prepared by this invention can efficiently separate MoO4. 2- It was also found that ReO4 in aqueous solution- and RuO4 - It has stable removal capabilities and can simultaneously separate multiple radioactive anions.

[0028] 3. The porous organic framework material prepared by this invention is simple to manufacture, low in cost, and highly selective, providing an efficient and economical practical technology for the deep purification of molybdenum-containing wastewater and the recovery of molybdenum resources, showing good prospects for industrial application. Attached Figure Description

[0029] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0030] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0031] Figure 1 The synthetic route diagram for preparing porous organic framework materials in Example 1 is shown.

[0032] Figure 2 The images are SEM images of the material prepared in Example 1 at different magnifications, where the magnifications from left to right are 10 k, 12 k, and 22 k.

[0033] Figure 3 The FT-IR image is of the material prepared in Example 1.

[0034] Figure 4 The image shows the SEM images of the material prepared in Comparative Example 1, with magnifications of 10 k and 5 k from left to right.

[0035] Figure 5 The image shows the appearance and SEM image of the material prepared in Comparative Example 2, with the material appearance image and SEM image at a magnification of 10 kJ from left to right.

[0036] Figure 6 The image shows the appearance and SEM image of the material prepared in Comparative Example 3, from left to right: the appearance image of the material and the SEM image at a magnification of 10 k.

[0037] Figure 7 The figure shows the effect of material adsorption of molybdate, where (a) compares different pH values ​​and (b) compares different contact times.

[0038] Figure 8 The figure shows the results of the isothermal adsorption experiment of the material, where (a) is the saturated adsorption capacity at pH=7 and (b) is the saturated adsorption capacity at pH=3.

[0039] Figure 9 For material adsorption of ReO4 - MoO4 2- RuO4 - The results of the experiment are shown in the figure, where (a) is the kinetic experimental results of the material and (b) is the comparison of the stability of the material at different pH values. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] Example 1 provides a porous organic framework material, the synthesis route of which is as follows: Figure 1 As shown. The preparation method includes the following steps:

[0043] S1. Dissolve 0.14 g of 1,3,6,8-tetra(1H-imidazol-1-yl)pyrene and 0.14 g of 1,2,4,5-tetra(bromomethyl)benzene in 20 mL of ultra-dry DMF (99.8%, Amex, water content <50 ppm), and sonicate for 30 min to obtain a mixture;

[0044] S2. The mixture was transferred to a polytetrafluoroethylene microwave tube and placed in a microwave reactor. The temperature was 100℃ and the reaction was carried out for 4 hours. After the reaction was completed, the mixture was cooled to room temperature. The product was separated and washed three times each with ultra-dry DMF, deionized water and anhydrous ethanol. The product was then soaked in a saturated NaCl solution for 24 hours. After soaking, the product was separated and dried to obtain a cationic polymerized porous organic framework material, denoted as CPN-M-1.

[0045] The material was characterized and tested, and the results were as follows: Figure 2-3 The SEM and FT-IR images shown demonstrate the successful synthesis of CPN-M-1 material, which exhibits relatively uniform and regular spherical particles.

[0046] Comparative Example 1

[0047] Comparative Example 1 provides a method for preparing a porous organic framework material, which differs from Example 1 in that conventional analytical grade DMF is used instead of ultra-dry DMF.

[0048] The results analysis for Comparative Example 1 can be found in [link to analysis]. Figure 4 The results showed that, compared with the material using ultra-dry DMF exhibiting a uniform and regular spherical structure under SEM, conventionally analyzed DMF did not show a clear regular morphology, indicating that the use of ultra-dry DMF in the preparation of this invention is necessary. Therefore, ultra-dry DMF was used to prepare the material in subsequent experiments.

[0049] Comparative Example 2

[0050] The difference between Comparative Example 2 and Example 1 is that the reaction temperature in S2 is 90 °C and 110 °C.

[0051] The results analysis chart for Comparative Example 2 is shown below. Figure 5 As shown in the figure, the reaction synthesis failed, no material was generated, and the material exhibited an irregular morphology under SEM.

[0052] Comparative Example 3

[0053] Difference between Comparative Example 3 and Example 1: Change in reactants in S1:

[0054] S1. Dissolve 0.14 g of 1,3,6,8-tetra(1H-imidazol-1-yl)pyrene and 0.14 g of 1,3,5-tris(bromomethyl)benzene in 20 mL of ultra-dry DMF, and sonicate for 30 min to obtain a mixture;

[0055] S2. Transfer the mixture to a polytetrafluoroethylene microwave tube, place it in a microwave reactor, heat it at 100 ℃ for 4 h, and follow the same steps as in Example 1.

[0056] The results analysis chart for Comparative Example 3 is shown below. Figure 6 As shown in the figure, a fluorescent material was synthesized, but the material exhibited an irregular particle structure under electron microscopy. Therefore, this experiment screened the best raw materials to prepare CPN-M-1 and carried out subsequent adsorption experiments.

[0057] Application Example 1

[0058] 5 mg of CPN-M-1 was weighed and added to 5 mL of aqueous solutions containing 10 ppm Mo with pH values ​​of 2, 4, 6, 8, 10, and 12, respectively. The pH was adjusted using 0.1 mmol / L HNO3 or NaOH aqueous solution. The resulting mixed solutions were stirred at 25 °C and 150 rpm for 5 min, filtered through a 0.22 μm membrane filter, and the Mo concentration in the solutions was determined by ICP-OES.

[0059] The results are as follows Figure 7 As shown in (a), when the pH value is in the range of 2-10, the CPN-M-1 material has a positive effect on MoO4. 2- The removal rate is high, consistently maintained above 90%, reaching a maximum removal rate of 96.69% at pH=8, initially demonstrating that the CPN-M-1 material exhibits good pH stability and adsorption selectivity. However, at pH=12, due to the competing ion OH- in the solution... - Significantly increased, for MoO4 2- The removal rate decreased. Within the pH range of 2-10, MoO4... 2- The partition coefficient first decreases and then increases, reaching its maximum value of 46499.11 mL / g at pH=10.

[0060] Table 1 Material effect on MoO4 2- Adsorption experimental results under different pH conditions

[0061]

[0062] Allocation coefficient:

[0063] C0: Concentration of solute in the solution before adsorption, mg / L.

[0064] C e : The concentration of solute in the solution after adsorption equilibrium, in mg / L.

[0065] V: Volume of the solution, in L.

[0066] m: Mass of the material, in grams.

[0067] Application Example 2

[0068] Five mg of CPN-M-1 material was weighed and added to 5 mL of an aqueous solution containing 10 ppm Mo for adsorption kinetics experiments. The experiments were conducted at 25 °C. After stirring at 180 rpm for set times (1, 5, 10, 30, 60, 90, and 120 min), samples were taken at different time points and filtered through a 0.22 μm membrane filter before analysis. The residual Mo concentration in the solution at a given time point was determined using ICP-OES, and the effect on MoO4 concentration was calculated. 2- Removal rate R t .

[0069] Table 2 Material effect on MoO4 2- Adsorption time experimental results

[0070]

[0071] When only the contact time between the adsorbent and the reaction solution is changed, the adsorption results are as follows: Figure 7 As shown in (b) of the figure. The results show that with increasing contact time, within 1-5 min, MoO4... 2- The removal efficiency of MoO4 gradually increased. 2- The partition coefficient initially increases, reaching 40666.67 mL / g at 5 min, and then fluctuates within a small range over the following time, reaching its target for MoO4 at approximately 5 min. 2- Adsorption equilibrium was reached and remained stable during the subsequent contact time. To further highlight the adsorption advantages of CPN-M-1, it was compared with representative adsorbent materials reported in the literature. For example, the chitosan system required 15 minutes to reach adsorption equilibrium. [1] The equilibrium time for systems containing strong cationic polymers such as polyethyleneimine (PEI) is approximately 120-180 min. [2] Compared with comparative materials, the material of the present invention has significant advantages in adsorption rate, and can achieve adsorption of MoO4 even at low concentrations. 2- Deep removal.

[0072] Application Example 3

[0073] 5 mg of CPN-M-1 was weighed and added to 5 mL of aqueous solutions with different Mo concentrations (10, 50, 100, 200, 400, 600, 800, 1000, and 1200 ppm) to explore the saturated adsorption capacity at pH 3 and 7. The pH was adjusted using 0.1 mmol / L HNO3 or NaOH aqueous solution. The resulting mixed solutions were stirred at 25 °C and 150 rpm for 5 min, filtered through a 0.22 μm membrane filter, and the Mo concentration was determined using ICP-OES.

[0074] The results of the isothermal adsorption experiment are as follows Figure 8 As shown, (a) illustrates the effect of CPN-M-1 on MoO4 at pH=7. 2- The saturated adsorption capacity was 239.24 mg / g, while (b) shows the adsorption capacity of CPN-M-1 for MoO4 at pH=3. 2- The saturated adsorption capacity can be significantly increased to 522.02 mg / g, which is about 2.18 times that of the former, and is the highest among similar cationic polymer materials reported to date.

[0075] To further highlight the adsorption advantages of CPN-M-1, it was compared with representative adsorbent materials reported in the literature. For example, biochar-based materials (such as DFBC) have a maximum adsorption capacity of 459.3-487.9 mg / g under the same pH conditions.[3] The static adsorption capacity of the nano-Zr(OH)4 gel at 25 °C was 292.4 mg / g. [4] CPN-M-1 is superior to the aforementioned materials. Furthermore, a viologen-based cationic organic polymer (VBCOP) exhibits good performance against ReO4 within a pH range of 2-8. - and MoO4 2- It exhibits good adsorption performance, especially for MoO4. 2- The saturated adsorption capacity can reach 196 mg / g [5] Its adsorption capacity is still lower than that of CPN-M-1. Furthermore, although a ZIF-8-NH2 / cellulose composite aerogel (CPEZN) showed an adsorption capacity of 872.39 mg / g for Mo(VI) at pH=3, its use is limited due to its relatively complex preparation process and its susceptibility to framework collapse and potential secondary zinc contamination caused by zinc ion leaching in strongly acidic environments. [6] Comprehensive comparisons show that CPN-M-1 exhibits a significant competitive advantage among numerous reported materials due to its simple preparation process and outstanding saturated adsorption capacity, especially suitable for MoO4 in weakly acidic wastewater. 2- Highly efficient removal.

[0076] Application Example 4

[0077] This invention also discovered that the CPN-M-1 material can simultaneously adsorb ReO4 in aqueous solution. - MoO4 2- RuO4 - Preparation of ReO4 - MoO4 2- RuO4 - A mixed solution with a molar concentration ratio of 1:1:1 and a Re concentration of 10 ppm was prepared. 5 mg of CPN-M-1 was weighed and added to 5 mL of the above mixed solution. The resulting mixed solution was stirred at 25 °C and 150 rpm for 5 min, filtered through a 0.22 μm membrane filter, and the concentrations of Re, Mo, and Ru in the solution were determined by ICP-OES.

[0078] like Figure 9 In (a), the kinetic experimental results of CPN-M-1 show that the CPN-M-1 material has a positive effect on ReO4. - MoO4 2- RuO4 - The removal experiments showed extremely excellent adsorption kinetics. Specifically, MoO4... 2- RuO4 - The adsorption rate is relatively fast, reaching adsorption equilibrium within just 30 seconds. In contrast, ReO4...- The rate is relatively slow, reaching equilibrium in about 1 minute of contact, and the removal rate is >98%.

[0079] From Table 3 and Figure 9 As shown in (b), the CPN-M-1 material exhibits a relatively stable removal rate within the pH range of 2-10, while its removal rate for MoO4 decreases when pH > 10. 2- ReO4 - The removal rate begins to decrease. It is important to note that in strongly alkaline solutions, RuO4... - It can indirectly generate RuO2·2H2O (black precipitate), which can be removed by filtration.

[0080] To further highlight the core advantages of the CPN-M-1 material of this invention in rapid capture and multi-component synergistic removal, a systematic comparative analysis was conducted with representative advanced adsorption materials reported in recent years. Existing studies have shown that the adsorption of ReO4⁻ by an ion-imprinted polymer typically requires approximately 30 minutes to reach equilibrium. [7] While imidazolium-functionalized cationic polymers exhibit high adsorption capacity, their kinetic processes generally require more than 10 minutes to reach equilibrium. [8] .

[0081] Furthermore, most of the aforementioned comparative materials reported in the literature only focus on a single ReO4. - / MoO4 2- It exhibits excellent performance. The core breakthrough of CPN-M-1 lies not only in its stability within a stable pH range (2-10), but also in its ability to simultaneously process ReO4 at an extremely high rate (30 s-1 min) in the same complex solution. - MoO4 2- RuO4 - Its efficient removal makes it highly promising for application in the treatment of complex radioactive waste liquids or industrial wastewater.

[0082] Table 3. Effects of different pH conditions on ReO4 materials 2- MoO4 2- RuO4 - Removal rate experimental results

[0083]

[0084] The above: [1] Study on adsorption and desorption of molybdate in polluted water using chitosan adsorbent. Journal of Water Treatment Engineering, 23, 13-19. https: / / doi.org / 10.1016 / j.jwpe.2018.02.016. [2] Huang, B., Liu, Y., Li, B., Wang, H., Zeng, G. (2019). Adsorption mechanism of anionic dyes on polyethyleneimine-modified magnetic core-shell Fe3O4@SiO2 nanoparticles. Royal Society of Chemistry, 9 (56), 32462–32471. https: / / doi.org / 10.1039 / c9ra06299h. [3] Das, NK, Navarathna, CM, Alchouron, J., Arwenyo, B., Rahman, S., Hoffman, B., Lee, K., Stokes, S., Anderson, R., Perez, F., Mohan, D., Pittman, CU, Jr., Mlsna, T. 2023. Efficient removal of molybdate from water using Douglas fir biochar and its iron oxide hybrid. Journal of Hazardous Materials, 443, 130257. https: / / doi.org / 10.1016 / j.jhazmat.2022.130257. [4] Ramadan, HE, El-Amir, MA, Mostafa, M. 2022. Adsorption of molybdate-molybdenum-99 by nano-zirconium hydroxide gel. Applied Radiation and Isotopes, 181, 110092. https: / / doi.org / 10.1016 / j.apradiso.2021.110092. [5] Zhao Pengwei, Ding Mu, Chen Shanyong, Jin Yongdong, Xia Chuanqin. (2021). Application of cationic organic polymers based on viologen for the separation of molybdenum and technetium. Isotopes, 34(6), 539-548. https: / / doi.org / 10.7538∕tws.2021.34.06.0539. [6] Qiu, Z., Gao, F., Zhang, Y., Li, J., You, Y., Lv, X., Dang, J.2024. Advancing Wastewater Treatment and Metal Recovery: Amination-modified ZIF-8 Composite Cellulose Aerogel as an Innovative Biomass Adsorbent to Enhance Molybdenum Ion Adsorption. Separation and Purification Techniques, 338, 126478. https: / / doi.org / 10.1016 / j.seppur.2024.126478. [7] Zhang, X., Jia, W., Li, D. et al. Synthesis and adsorption properties of perrhenate ion-imprinted polymers. Polymer Research Impurities, 27, 201 (2020). https: / / doi.org / 10.1007 / s10965-020-02172-8. [8] Huang, M., Kan, L., Zhao, W., Wang, Y., Xiong, Y., Shan, W., Lou, Z. 2021. Imidazolium-based ionic liquid polymers for TcO4 - Or ReO4 - Highly efficient selective capture. Journal of Chemical Engineering, 421, 127763. https: / / doi.org / 10.1016 / j.cej.2020.127763.

[0085] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a porous organic framework material, characterized in that, Includes the following steps: S1. Dissolve 1,3,6,8-tetrakis(1H-imidazol-1-yl)pyrene and 1,2,4,5-tetrakis(bromomethyl)benzene in N,N-dimethylformamide organic solvent to obtain a mixed solution; wherein the water content of N,N-dimethylformamide organic solvent is ≤0.1 wt%; S2. The mixture was heated and reacted in a microwave reactor. After the product was separated and washed, it was soaked in a saturated NaCl solution. After soaking, the product was separated and dried to obtain the porous organic framework material CPN-M-1. The chemical structural formula of the porous organic framework material CPN-M-1 is as follows: 。 2. The preparation method according to claim 1, characterized in that, The 1,3,6,8-tetra(1H-imidazol-1-yl)pyrene and 1,2,4,5-tetra(bromomethyl)benzene were dissolved in a molar ratio of 1:

1.

3. The preparation method according to claim 1, characterized in that, The conditions for the heating reaction are: temperature 100 ℃, reaction time 4 h.

4. The preparation method according to claim 1, characterized in that, The washing process involves sequentially washing with N,N-dimethylformamide, deionized water, and anhydrous ethanol, wherein the water content of N,N-dimethylformamide is ≤0.1 wt%.

5. The preparation method according to claim 1, characterized in that, The soaking time is 5-24 hours.

6. A porous organic framework material, characterized in that, The preparation method according to any one of claims 1-5 is obtained.

7. A method for efficiently adsorbing and separating molybdate ions from water using a porous organic framework material according to claim 6, characterized in that, Includes the following steps: The porous organic framework material was added to a water body containing molybdate. Adjust the pH value to the range of 2-10 and mix and stir. After filtration, measure the concentration of molybdate.

8. The method according to claim 7, characterized in that, The pH value is 3.

9. The method according to claim 7, characterized in that, The mixing time is 5 minutes.

10. An application of the porous organic framework material according to claim 6 in the efficient adsorption and separation of molybdate in environmental water.

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