Preparation method of defect-rich Ce-MOF

Abstract

The application belongs to the technical field of Ce-MOF, and provides a preparation method of Ce-MOF rich in defects, which comprises the following steps: dissolving CeCl3.7H2O solid in a first mixed solution, stirring at room temperature to make it completely dissolved, and obtaining a second mixed solution; uniformly mixing 2-NH2-p-terephthalic acid into the second mixed solution to obtain a third mixed solution, uniformly mixing propionic acid into the third mixed solution to obtain a fourth mixed solution, transferring the fourth mixed solution into a reaction kettle, reacting for a period of time at a certain temperature, cooling to room temperature after the reaction is completed, and obtaining a preliminary sample; placing the preliminary sample in a fifth mixed solution, centrifugally collecting a final product, washing the final product with DMF and methanol in sequence, then performing solvent exchange by immersing the final product in methanol, drying, and then activating the final product in an oven to obtain a sample Ce-MOF-PA.

Description

Technical Field

[0001] This invention belongs to the field of Ce-MOF technology, and particularly relates to a method for preparing defect-rich Ce-MOF. Background Technology

[0002] In recent decades, with the widespread and increasingly serious problem of water pollution, people have been committed to exploring water pollutant remediation technologies. Phosphorus is a mineral nutrient that is essential for plant growth and maintaining the balance of ecosystems. However, due to domestic, mining, industrial, agricultural, and municipal activities, excessive phosphate concentrations in the aquatic environment can induce eutrophication, causing excessive algal growth, accelerating dissolved oxygen consumption, and creating a low-oxygen environment that affects the growth of other organisms, leading to an imbalance in aquatic systems. Although nitrogen also plays a role, research shows that phosphorus is the main culprit of eutrophication, thus requiring attention to remove excess phosphate from water. Meanwhile, phosphorus emissions from aquaculture are also a widely concerned issue. Aquatic animals mainly obtain phosphorus through feed, but phosphorus requirements typically vary from animal to animal, generally between 0.3% and 2%, thus limiting phosphorus utilization; most of the applied phosphorus is excreted into the aquatic environment. Besides uneaten feed, phosphorus accumulation can also occur from aquatic animal excrement (such as feces and urine), untreated remains of farmed organisms, and added chemicals. This promotes the growth of odor-causing bacteria (such as Streptomyces), severely impacting the taste of fish. Therefore, phosphorus poses a significant threat to human health and the ecological environment. Developing more effective phosphorus adsorption and recovery technologies is currently a crucial research topic in environmental, materials, and engineering fields.

[0003] Phosphorus in water and wastewater is usually in the form of orthophosphate (PO4). 3- HPO4 2- and H2PO4 -Phosphorus exists in three forms: phosphorus, polyphosphate, and organophosphonates. During natural and biological oxidation processes, phosphorus in its complex forms is typically converted to orthophosphate, making orthophosphate the most common form and the primary target for recovery. Furthermore, orthophosphate is the only form that most plants can absorb. Therefore, environmental phosphorus removal research largely focuses on orthophosphate removal. Currently, various physical, chemical, and biological methods have been used to remove and recover phosphorus from wastewater, such as deep oxidation, biological treatment, membrane separation, precipitation, and adsorption. Among these, adsorption is the most convenient and cost-effective method, with commonly used adsorbents including carbonaceous materials, zeolites, metal oxides, nanoparticle-modified materials, resins, and metal-organic frameworks (MOFs). In recent years, there has been increasing interest in using MOFs for the efficient recovery and removal of phosphorus. MOFs are porous coordination polymers that form multidimensional periodic structures with large specific surface areas, high porosity, and high thermal stability. These properties make MOFs ideal materials for phosphorus adsorption and diffusion. Moreover, the size and shape of the pores can be adjusted to improve the selective adsorption capacity and recovery rate of phosphorus.

[0004] Cerium (Ce), as the most abundant rare earth element, has a wide range of applications, including catalysts, adsorbents, phosphors, magnetic materials, sensors, and alloys. Notably, the Ksp of the metal phosphate CePO4 (Ksp = 1.0 × 10⁻⁶) is... -23 This indicates a strong bond between cerium and phosphate, suggesting that cerium-based materials possess good phosphorus removal capabilities. Considering ligand exchange as the primary intrasphere interaction in chemisorption, Ce(OH)3 (Ksp = 1.6 × 10⁻⁶) -20 ) and Ce(OH)4 (Ksp = 2×10 -48 The significant difference in solubility cannot be ignored. The extremely strong binding between Ce(IV) and the hydroxyl group may directly inhibit the adsorption of phosphate on the adsorbent surface through ligand exchange. The Ksp of Ce(OH)3 indicates that Ce(OH)3 is more soluble than CePO4, suggesting that ligand exchange is highly likely to occur between Ce(OH)3 and CePO4. To improve adsorption performance, defect engineering is generally used to increase the number of unsaturated sites on the metal. Defects are usually related to unoccupied coordination sites on the metal clusters of MOFs. By understanding and controlling the type and level of defects inside MOFs, abundant adsorption active sites (such as unsaturated coordination centers) can be introduced. Currently, there are no reports on the adsorption of phosphate by materials with Ce-based metal-organic framework defects created by adding monocarboxylic acids. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a method for preparing defect-rich Ce-MOF.

[0006] The advantages and beneficial effects of this invention compared to the prior art are as follows:

[0007] This invention provides a method for preparing defect-rich Ce-MOFs, comprising:

[0008] CeCl3·7H2O solid was dissolved in a first mixed solution containing DMF and H2O, and stirred at room temperature until completely dissolved to obtain a second mixed solution;

[0009] 2-NH2-terephthalic acid was uniformly mixed into the second mixed solution to obtain the third mixed solution. Then, propionic acid was uniformly mixed into the third mixed solution to obtain the fourth mixed solution. The fourth mixed solution was transferred to a reaction vessel, and the reaction temperature was controlled at 90~120℃. The reaction time was controlled at 12~20 h. After cooling to room temperature, a preliminary sample was obtained.

[0010] The preliminary sample was placed in a fifth mixed solution containing HCl and DMF, and the final product was collected by centrifugation. It was washed with DMF and methanol in sequence, then soaked in methanol for solvent exchange, dried, and then activated in an oven at 130~160℃ to obtain the sample Ce-MOF-PA.

[0011] The present invention further provides a defect-rich Ce-MOF prepared by the above method.

[0012] The present invention further provides the application of defect-rich Ce-MOF in the adsorption of phosphate.

[0013] 1. The technical solution of the present invention uses CeCl3·7H2O as a metal source, 2-NH2-terephthalic acid as a ligand, and propionic acid as a modifier to finally obtain a defect-rich Ce-MOF.

[0014] 2. Defect-rich Ce-MOFs possess abundant mesoporous structures, adjustable pore sizes, controllable morphologies, abundant unsaturated metal sites, and amino functional groups, enabling them to rapidly adsorb phosphates.

[0015] 3. The defect-rich Ce-MOF exhibits excellent stability in aqueous solutions and demonstrates strong adsorption and removal rates over a wide pH range. Furthermore, it does not cause secondary pollution of water bodies.

[0016] 4. The process of this invention is simple and easy to implement, requiring no expensive equipment or harsh production conditions. The prepared material has controllable morphology, is non-toxic, odorless, and pollution-free, and can be reused. This adsorbent will greatly reduce the adsorption cost of phosphates and is suitable for the adsorption of phosphates in industrial wastewater or aquaculture effluent. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The image shows the FT-IR spectrum of the Ce-MOF-PA material prepared in Example 3 of this invention.

[0019] Figure 2 This is a SEM image of the Ce-MOF-PA material prepared in Example 3 of the present invention;

[0020] Figure 3 The image shows the XRD pattern of the Ce-MOF-PA material prepared in Example 3 of this invention.

[0021] Figure 4 The image shows the BET plot of the Ce-MOF-PA material prepared in Example 3 of this invention.

[0022] Figure 5 This is the isothermal adsorption diagram of the Ce-MOF-PA material prepared in Example 3 of the present invention. Detailed Implementation

[0023] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present 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 of the present invention and are not intended to limit the present invention.

[0024] The present invention provides a method for preparing defect-rich Ce-MOFs, the specific steps of which are as follows:

[0025] CeCl3·7H2O solid was dissolved in a first mixed solution containing DMF and H2O, and stirred at room temperature until completely dissolved to obtain a second mixed solution;

[0026] 2-NH2-terephthalic acid was uniformly mixed into the second mixed solution to obtain the third mixed solution. Then, propionic acid was uniformly mixed into the third mixed solution to obtain the fourth mixed solution. The fourth mixed solution was transferred to a reaction vessel and reacted at a certain temperature for a period of time. After the reaction was completed, it was cooled to room temperature to obtain a preliminary sample.

[0027] The initial sample was placed in a fifth mixed solution containing HCl and DMF and incubated at 90°C for 12 hours. After the time was up, the solution was centrifuged, and the filter residue was collected. The filter residue was then placed back into the fifth mixed solution of the same composition and volume, and the process of incubation at 90°C for 12 hours, followed by centrifugation and residue collection, was repeated at least three times to remove propionic acid as much as possible. The final product was collected by centrifugation and washed once each with appropriate amounts of DMF and methanol. Then, it was soaked in methanol for solvent exchange, dried, and activated in an oven at a specific temperature for a period of time to obtain the Ce-MOF-PA sample.

[0028] In some specific embodiments, CeCl3·7H2O is mixed with the first mixed solution in a molar-to-volume ratio of 3.5 mmol:15 mL to 3.5 mmol:60 mL. When 3.5 mmol:30 mL is used, cerium chloride heptahydrate can be fully dissolved and dispersed in the first mixed solution, which is beneficial to the smooth progress of subsequent reactions, thereby ensuring the stability and reliability of the experimental results.

[0029] In the first mixed solution, DMF and H2O are mixed in a volume ratio of 1:1 to 4:1. When a ratio of 3:1 is used, the metal ions and organic ligands are better dispersed and contacted, which promotes the nucleation and growth of MOF and is conducive to the formation of MOF crystals with regular structure and good crystallinity.

[0030] In some specific embodiments, 2-NH2-terephthalic acid is mixed with the second mixed solution at a molar-to-volume ratio of 0.5 mmol:30 mL to 3 mmol:30 mL. When a molar-to-volume ratio of 1.75 mmol:30 mL is used, the metal ions and 2-NH2-terephthalic acid can be arranged in an orderly manner according to a specific coordination pattern, forming a regular crystal structure and a suitable pore size. Propionic acid is mixed with the third mixed solution at a volume-to-volume ratio of 4.5 mL:30 mL to 7.5 mL:30 mL. When a volume-to-volume ratio of 6.5 mL:30 mL is used, propionic acid and 2-NH2-terephthalic acid compete, which can both construct abundant unsaturated metal active sites and maintain the integrity of the crystal.

[0031] In some specific embodiments, the reaction temperature in the reactor is controlled at 90~120℃, and the reaction time is controlled at 12~20 h. When the reaction is carried out at 110℃ for 16 h, the activation energy and reaction rate of the reaction system are moderate, and the yield is the highest.

[0032] In some specific embodiments, the mass-to-volume ratio of the initial sample to the fifth mixed solution is 1 g:5 mL to 1 g:20 mL. When the mass-to-volume ratio is 1 g:10 mL, propionic acid is removed to the maximum extent, resulting in abundant active sites.

[0033] In some specific embodiments, the volume ratio of HCl to DMF in the fifth mixed solution is 1:7.

[0034] In some specific embodiments, the preliminary sample was placed in a fifth mixed solution of HCl and DMF and left at 80–100°C for 6–18 h. When left at 90°C for 12 h, propionic acid and unreacted reactants were sufficiently removed.

[0035] In some specific embodiments, the sample was soaked in methanol multiple times, each time for 12–36 hours, to facilitate solvent exchange. When soaked twice for a total soaking time of 24 hours, the DMF remaining in the pores was fully replaced by methanol. Drying was then carried out at 50–90°C for 6–18 hours. When dried at 60°C for 12 hours, the methanol in the sample was fully evaporated, and the sample was in a dry state.

[0036] In some specific embodiments, the preliminary sample is placed in a fifth mixed solution containing HCl and DMF, centrifuged to collect the final product, washed sequentially with DMF and methanol, then immersed in methanol for solvent exchange, dried, and then activated in an oven at 130-160°C for 5-8 hours. When activated at 150°C for 6 hours, residual solvent molecules (such as DMF) in the sample detach from the channels and surface of the MOF, making the channels more regular and the pore size distribution more uniform.

[0037] This invention provides a defect-rich Ce-MOF prepared by the above-described method. The defect-rich Ce-MOF exhibits a three-dimensional hierarchical pore structure: macropores with a pore size greater than 50 nm serve as rapid mass transfer channels, mesopores with a pore size of 2-50 nm are used to construct a molecular sieve network, and micropores with a pore size less than 2 nm are used to provide high-density adsorption sites.

[0038] Based on the morphological characteristics and coordination chemistry properties of phosphates in wastewater, this invention innovatively employs a defect engineering control strategy to successfully construct a cerium-based organic framework material (Ce-MOF-PA) with a multi-level porous structure and abundant active sites. Its core innovations are: (1) Defect construction mechanism induced by coordination competition. During the solvothermal synthesis process, propionic acid is precisely introduced as a competing ligand to form a dynamic coordination equilibrium system with the main ligand 2-NH2-terephthalic acid. Based on the soft and hard acid-base theory of coordination chemistry, monodentate propionic acid and polydentate aminoterephthalic acid generate a gradient competition effect during the coordination of cerium ions, thereby forming missing coordination vacancies at the metal nodes and constructing a defect structure containing high-density unsaturated coordination sites. (2) Multi-level porous synergistic mass transfer system. The material exhibits a typical three-dimensional hierarchical pore structure: macropores serve as fast mass transfer channels, mesopores construct a molecular sieve network, and micropores provide high-density adsorption sites. BET characterization showed that the average pore size reached 39.7287 nm, which is significantly larger than that of the traditional Ce-MOF material (26.2713 nm), providing a favorable environment for the rapid diffusion and adsorption of phosphorus. (3) Synergistic adsorption mechanism with multiple effects. The chemisorption dominated by coordination vacancies, the hydrogen bonding effect of amino functional groups, and the electrostatic attraction effect work together to achieve an adsorption capacity of 178.7 mg / g (pH=6), which is 49.5% higher than that of the original Ce-MOF (119.5 mg P / g). Studies have shown that the material has a stable structure, good adsorption performance for phosphate in water, fast adsorption and high removal rate, and does not produce secondary pollution. The raw materials required for this process are abundant, the preparation process is simple, cost-saving, and easy to use, making it suitable for the removal of phosphate in industrial wastewater or aquaculture tail water.

[0039] This invention has undergone numerous experiments, and some of the experimental results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0040] The instruments and characterization methods used in this invention are as follows:

[0041] (1) FT-IR was performed using a Spectrum One infrared spectrometer from Pepperl, Inc. (PE). Solid samples were prepared by pressing KBr pellets, and liquid samples were coated on KBr wafers. The wavelength range of the absorption spectrum scan was 4000–500 cm⁻¹. -1 Scan 3 times.

[0042] (2) The X-ray diffractometer (XRD) used was a German Bruker D8 ADVANCE wide-angle X-ray diffractometer with a Cu target (λ=1.54 Å) and a scanning range of 5~90°.

[0043] (3) Scanning electron microscope (SEM) was used to record the images of the scanned samples using a Hitachi SU8010.

[0044] (4) The present invention uses the molybdenum blue spectrophotometric method to determine the phosphate concentration in the solution after adsorption of the adsorbent.

[0045] Take 20 mL of KH2PO4 solution (concentration of 10~500 mgP / L) and put it into a 50 mL beaker. Adjust the pH of the solution to 2~10. Then add a certain amount of Ce-based metal-organic framework material to the solution and stir for a certain time. Centrifuge the adsorbed solution at high speed for 5 min. Take a certain amount of the supernatant after centrifugation into a 25 mL stoppered colorimetric tube, dilute to volume with deionized water and shake well. Determine the adsorption capacity and removal rate of P adsorbed by the adsorbent according to the following formulas (1) and (2).

[0046] (1)

[0047] (2)

[0048] In the formula, Q e The amount of P adsorbed by the adsorbent (mg / g); C 0 and C e The values ​​represent the P concentration (mg / L) in the solution before adsorption and the P concentration (mg / L) in the solution after adsorption. m The mass (g) of the adsorbent; V The volume of the solution is expressed in L. R The removal rate (%) of P in the solution.

[0049] The chemical reagents used in the embodiments of this invention were provided by Sinopharm Chemical Reagent Co., Ltd.

[0050] Comparative Example 1:

[0051] (1) First, 3.5 mmol of CeCl3·7H2O solid was dissolved in 30 mL of a mixed solution of DMF and H2O (V:V=3:1) and stirred at room temperature until completely dissolved. Then, 1.75 mmol of 2-NH2-terephthalic acid ligand was added to the above mixed solution and stirred thoroughly to make the solution homogeneous. Finally, the solution was transferred to a reaction vessel and reacted at 110 °C for 16 h.

[0052] (2) After the reaction was completed, the sample was cooled to room temperature and placed in 20 mL of HCl and DMF solution. It was then placed at 90 °C for 10 h and repeated 3 times. The final product was collected by centrifugation, washed sequentially with DMF and methanol, and then soaked in methanol twice for 24 h each time for solvent exchange. Finally, it was dried at 60 °C for 12 h and then activated in an oven at 130 °C for 8 h to obtain the Ce-MOF sample. The adsorption capacity for phosphate was tested to be 87 mg / g.

[0053] Example 1:

[0054] (1) First, 3.5 mmol of CeCl3·7H2O solid was dissolved in 30 mL of a mixed solution of DMF and H2O (V:V=3:1) and stirred at room temperature until completely dissolved. Then, 1.75 mmol of 2-NH2-terephthalic acid ligand was added to the above mixed solution and stirred thoroughly to make the solution homogeneous. Then, 4.5 mL of propionic acid was uniformly mixed into the above solution. Finally, the solution was transferred to a reaction vessel and reacted at 110 °C for 16 h.

[0055] (2) After the reaction was completed, the sample was cooled to room temperature and placed in 20 mL of HCl and DMF solution. It was then placed at 90 °C for 10 h and repeated 3 times. The final product was collected by centrifugation, washed sequentially with DMF and methanol, and then soaked in methanol twice for 24 h each time for solvent exchange. Finally, it was dried at 60 °C for 12 h and then activated in an oven at 130 °C for 8 h to obtain the Ce-MOF-PA sample. The adsorption capacity of phosphate was tested to be 115 mg / g.

[0056] Example 2:

[0057] The procedure was essentially the same as in Example 1, except that 5.5 mL of propionic acid was added. The adsorption capacity for phosphate was tested to be 117 mg / g.

[0058] Example 3:

[0059] The procedure was essentially the same as in Example 1, except that 6.5 mL of propionic acid was added. The adsorption capacity for phosphate was tested to be 123 mg / g.

[0060] Example 4:

[0061] The procedure was essentially the same as in Example 1, except that 7.5 mL of propionic acid was added. Testing showed that it adsorbed 120 mg / g of phosphate.

[0062] From the adsorption data of Comparative Example 1 and Examples 1-5, it can be seen that as the amount of propionic acid added increases, its adsorption of phosphate also increases to a certain extent. However, when the optimal addition amount of 6.5 mL is reached, the adsorption amount decreases with further increase of propionic acid. Therefore, the optimal addition amount is determined to be 6.5 mL.

[0063] Example 5:

[0064] The procedure was essentially the same as in Example 3, except that 6.5 mL of propionic acid was uniformly mixed into the above solution. Finally, the solution was transferred to a reaction vessel and reacted at 90°C for 16 h. The adsorption capacity for phosphate was tested to be 105 mg / g.

[0065] Example 6:

[0066] The procedure was essentially the same as in Example 3, except that 6.5 mL of propionic acid was uniformly mixed into the above solution. Finally, the solution was transferred to a reaction vessel and reacted at 100°C for 16 h. The adsorption capacity for phosphate was tested to be 115 mg / g.

[0067] Example 7:

[0068] The procedure was essentially the same as in Example 3, except that 6.5 mL of propionic acid was uniformly mixed into the above solution. Finally, the solution was transferred to a reaction vessel and reacted at 120°C for 16 h. The adsorption capacity for phosphate was tested to be 110 mg / g.

[0069] From the adsorption data of Examples 3 and 5-7, it can be seen that as the reaction temperature increases, the adsorption of phosphate also increases significantly, from 105 mg / g to 123 mg / g, an increase of about 15%. However, when the temperature increases further, the adsorption also decreases to some extent. Therefore, the optimal reaction temperature is confirmed to be around 110℃.

[0070] Depend on Figure 1 It can be known that 3478 cm -1 With 3359 cm -1 Corresponding to the vibrational modes νas(NH2) and νs(NH2) in the 2-NH2-BDC ligand, respectively, 1606 cm -1 Attributable to the stretching vibration of the aromatic ring C=C, 1254 cm -1 This corresponds to the stretching vibration of CN in aromatic amines. 1576 cm⁻¹ -1 With 841cm -1 They belong to Ce 3+ The Ce-O stretching vibration and Ce-OC bending vibration formed with the carboxylic acid oxygen atom prove that Ce is successfully coordinated with the ligand.

[0071] Depend on Figure 2 It is evident that the Ce-MOF-PA series materials all exhibit micron-sized rod-like morphologies, with surface exfoliation forming a hierarchical porous structure and through-cracks appearing between crystal planes. This indicates that an appropriate amount of propionic acid can introduce controllable surface roughness and porosity while maintaining the stability of the crystal structure, thereby exposing more Ce nodes. The defect-rich Ce-MOF exhibits a three-dimensional hierarchical pore structure: macropores with a pore size greater than 50 nm serve as rapid mass transfer channels, mesopores with a pore size of 2–50 nm are used to construct a molecular sieve network, and micropores with a pore size less than 2 nm provide high-density adsorption sites.

[0072] Depend on Figure 3 It can be seen that the diffraction peak positions of Ce-MOF-PA are in high agreement with those reported in the literature, proving the successful synthesis of the material and indicating that the dynamic competitive coordination of propionic acid does not affect the overall crystal structure.

[0073] Depend on Figure 4 It is evident that Ce-MOF-PA exhibits a typical Type IV isotherm, indicating the presence of irregular mesopores in the structure. Calculations using the BJH model show that the mesopore size of Ce-MOF-PA reaches as high as 39.73 nm, providing ideal channels for the rapid diffusion and adsorption of phosphorus and significantly optimizing the mass transfer kinetics of phosphate.

[0074] Depend on Figure 5 It can be seen that the adsorption isotherms of Ce-MOF-PA under different initial phosphate concentrations were fitted. The Langmuir model describes the adsorption behavior of both models more accurately than the Freundlich model, indicating that the adsorption process of phosphorus on the adsorbent is unimolecular adsorption. The model calculation shows that the maximum adsorption capacity of Ce-MOF-PA reaches 178.7 mg P / g, exhibiting a high adsorption capacity for phosphate, which is mainly attributed to the exposure of unsaturated Ce sites.

[0075] 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, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a defect-rich Ce-MOF, characterized in that, The method comprises: dissolving CeCl3·7H2O solid in a first mixed solution comprising DMF and H2O, in the first mixed solution, the volume ratio of DMF and H2O is 3:1, the ratio of CeCl3·7H2O solid to the first mixed solution is 3.5 mmol:30 mL in terms of the amount of substance to volume, and stirring at room temperature until complete dissolution to obtain a second mixed solution; uniformly mixing 2-NH2-terephthalic acid into the second mixed solution, the ratio of 2-NH2-terephthalic acid to the second mixed solution is 1.75 mmol:30 mL in terms of the amount of substance to volume, to obtain a third mixed solution, and then uniformly mixing propionic acid into the third mixed solution, the ratio of propionic acid to the third mixed solution is 6.5 mL:30 mL in terms of volume to volume, to obtain a fourth mixed solution, and then transferring the fourth mixed solution into a reaction kettle, controlling the reaction temperature at 110℃, and controlling the reaction time at 16 h, and after the reaction is completed, cooling to room temperature to obtain a preliminary sample; placing the preliminary sample in a fifth mixed solution comprising HCl and DMF, and placing at 90℃ for 12 h, after the time arrives, centrifuging the solution, and collecting the filter residue, then placing the filter residue again in the fifth mixed solution with the same composition and volume as before, and repeating the operation of placing at 90℃ for 12 h, after the time arrives, centrifuging the solution, and collecting the filter residue, and so on, repeating for more than 3 times, wherein the mass-volume ratio of the preliminary sample to the fifth mixed solution is 1g:10 mL, and the volume ratio of HCl to DMF in the fifth mixed solution is 1:7, centrifuging to collect the final product, washing with DMF and methanol in sequence, then soaking in methanol for 2 times, each time for 24 h, performing solvent exchange, and finally drying at 60℃ for 12 h, and then activating in an oven at 130℃ for 8 h, to obtain the defect-rich Ce-MOF, which exhibits a three-dimensional hierarchical pore structure: macropores with a pore size greater than 50 nm as a rapid mass transfer channel, mesopores with a pore size of 2-50 nm for constructing a molecular sieving network, and micropores with a pore size less than 2 nm for providing high-density adsorption sites. 2.A defect-rich Ce-MOF prepared by the method of claim 1. 3.Use of the defect-rich Ce-MOF of claim 2 in adsorbing phosphate.

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