Preparation method and application of defect-adjustable bimetallic MOFs modified adsorbent
By regulating the defects and surface morphology of bimetallic MOFs, combining specific carriers and organic ligands, an efficient bimetallic MOFs modified adsorbent was prepared, which solved the problem of poor reusability and desorption efficiency of bimetallic MOFs in the prior art, and achieved the improvement of efficient adsorption and anti-interference ability of amine trimethylene phosphonic acid.
Patent Information
- Application Number
- CN202510312018.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-17
- Publication Date
- 2025-06-13
AI Technical Summary
In the prior art, bimetallic MOFs have poor reusability and desorption efficiency in phosphate removal, and pure MOFs powder has solubility, low processing capacity, brittleness and safety risks, making it difficult to separate in aqueous solution, limiting its practical application.
By regulating the ratio of zirconium salt and rare earth element salt, controlling the surface morphology and defect degree of bimetallic MOFs, combining specific carriers and organic ligands, a bimetallic MOFs modified adsorbent that can regulate defects is prepared to improve its adsorption ability to amine trimethylene phosphonic acid.
It realizes efficient adsorption of amine trimethylene phosphonic acid, improves the selectivity and reusability of the adsorbent, enhances the anti-interference ability, and solves the problem of insufficient material stability and recycling in the prior art.
Smart Images
Figure CN120132807A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of adsorbent materials, and specifically relates to a preparation method and application of an adsorbent modified with regulable defective bimetallic MOFs. Background Art
[0002] Compared with single-metal MOF, bimetallic MOFs exhibit better performance and synergistic effects, including structural stability, selective catalysis, and adsorption selectivity. The coordination competition between different metals and ligands leads to different framework systems, thus resulting in different states and porosities. Due to the different coordination numbers of the involved metals, bimetallic MOFs often expose more or less metal-based coordination centers. Zirconium, cerium, and lanthanum are widely used as powerful metal adsorbents for phosphate removal and also have excellent anti-interference ability, but due to irreversible combination, their reusability and desorption efficiency are poor. Pure MOF powders have few practical applications due to their low solubility, poor processing ability, brittleness, potential safety problems of generating dust, and difficulty in separating from aqueous solutions. Summary of the Invention
[0003] The first object of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of an adsorbent modified with bimetallic MOFs with controllable defects and strong selectivity;
[0004] The second object of the present invention is to provide the application of the adsorbent modified with bimetallic MOFs.
[0005] The present invention adopts the following technical solutions:
[0006] (1) The present invention provides a preparation method of an adsorbent modified with regulable defective bimetallic MOFs, including:
[0007] S1. Dissolve zirconium salt and rare earth element salt in water, add hydrochloric acid and ethanol to obtain a mixed solution;
[0008] S2. Add a carrier to the mixed solution for soaking, filtering, and drying to obtain a precursor;
[0009] S3. Dissolve an organic ligand in N, N-dimethylformamide, add the precursor obtained in step S2, and carry out a hydrothermal reaction. After the reaction is completed, an adsorbent modified with bimetallic MOFs is obtained.
[0010] Further, in step S1, the rare earth element salt is cerium salt, and the mass ratio of the zirconium salt to the cerium salt is 1-9:2-6. By regulating the addition amounts of different ratios of the zirconium salt and the cerium salt, the synthesis
[0011] The surface morphology and defect degree of Zr-Ce-MOF-808@sponge, as well as the number of exposed effective metal active sites, are used to enhance the adsorption of aminotrimethylenephosphonic acid.
[0012] Furthermore, the mass ratio of the zirconium salt to the cerium salt is 0.7-1.9:1.
[0013] Furthermore, the zirconium salt is zirconium oxychloride octahydrate or zirconium chloride, and the cerium salt is cerium nitrate hexahydrate or ammonium cerium nitrate.
[0014] Furthermore, in step S1, the concentration of the zirconium salt in the mixed solution is 0.027 mol / L - 0.25 mol / L, the concentration of the cerium salt is 0.046 mol / L - 0.14 mol / L, the concentration of hydrochloric acid is 1.5 - 5 wt%, and the concentration of ethanol is 5 - 25 wt%.
[0015] Furthermore, in step S2, the carrier is a plant fiber sponge.
[0016] Furthermore, in step S3, the organic ligand is 1,3,5-benzenetricarboxylic acid.
[0017] Furthermore, step S3 is specifically: after dissolving 1,3,5-benzenetricarboxylic acid in N,N-dimethylformamide, adding the precursor for ultrasonic dispersion, then carrying out a hydrothermal reaction, and after the hydrothermal reaction is completed, filtering, washing, and drying to obtain the bimetallic MOFs modified adsorbent Zr-Ce-MOF-808@sponge.
[0018] Furthermore, the mass ratio of the precursor, N,N-dimethylformamide, and 1,3,5-benzenetricarboxylic acid is 2:30:1 - 3; the ultrasonic dispersion time is 30 - 50 min; the hydrothermal reaction temperature is 120 °C, and the hydrothermal reaction time is 24 h.
[0019] Furthermore, the washing process is: washing 3 - 5 times with N,N-dimethylformamide and ethanol solution; the drying temperature is 60 °C, and the drying time is 8 - 12 h.
[0020] Furthermore, in Zr-Ce-MOF-808@sponge, the loading amount of the Zr-Ce bimetal: Zr is 3 - 13 wt%, and Ce is 4 - 8 wt%.
[0021] Furthermore, in step S1, the rare earth element salt is a lanthanum salt; the mass ratio of the zirconium salt to the lanthanum salt is 1 - 13:2 - 7. By adjusting the addition amounts of different ratios of the zirconium salt and the lanthanum salt, the surface morphology and defect degree of the synthesized Zr-La-MOFs@201, as well as the number of exposed effective metal active sites, are changed to enhance the adsorption of aminotrimethylenephosphonic acid.
[0022] Furthermore, the zirconium salt is zirconium oxychloride octahydrate or zirconium chloride, and the lanthanum salt is lanthanum nitrate hexahydrate or lanthanum chloride.
[0023] Furthermore, in step S1, the concentration of the zirconium salt in the mixed solution is 0.027 mol / L - 0.36 mol / L, the concentration of the lanthanum salt is 0.046 mol / L - 0.16 mol / L, the concentration of hydrochloric acid is 1.5 - 5 wt%, and the concentration of ethanol is 5 - 25 wt%.
[0024] Furthermore, in step S2, the carrier is D201 resin.
[0025] Furthermore, in step S3, the organic ligand is terephthalic acid.
[0026] Furthermore, step S3 is specifically as follows: Dissolve terephthalic acid in N,N-dimethylformamide, then add the precursor for hydrothermal reaction. After the hydrothermal reaction is completed, filter, wash, and dry to obtain the bimetallic MOFs modified adsorbent Zr-La-MOFs@201.
[0027] Furthermore, the mass ratio of the precursor, N,N-dimethylformamide, and terephthalic acid is 1:30:1 - 3; the hydrothermal reaction temperature is 120 °C, and the hydrothermal reaction time is 24 h.
[0028] Furthermore, the washing process is as follows: Wash with N,N-dimethylformamide and ethanol solution 3 - 5 times; the drying temperature is 60 °C, and the drying time is 8 - 12 h.
[0029] Furthermore, in Zr-La-MOFs@201, the loading amount of the Zr-La bimetal: Zr is 3 - 13 wt%, and La is 4 - 7 wt%
[0030] (2) The present invention also provides the application of the adjustable defect bimetallic MOFs modified adsorbent prepared by the above method in the adsorption of amino trimethylene phosphonic acid.
[0031] Beneficial effects
[0032] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:
[0033] 1. The present invention simplifies the steps of creating defects in MOF. By adjusting the addition amount of different metal precursors, the regulation of defects can be achieved. The bimetallic MOFs improve the adsorption capacity and selectivity of single-metal MOF, improve the removal effect of organic phosphine, and the adsorption capacity of amino trimethylene phosphonic acid is as high as 146 mg / g;
[0034] 2. The present invention can synthesize bimetallic MOFs with stable performance and controllable defects on different metals, different ligands, and different carriers. The exposed metal centers effectively improve the selectivity of the material, and the selection of the carrier improves the stability and recycling rate of the adsorbent.
[0035] 3. The adsorbent modified with the bimetallic MOFs prepared by the present invention can selectively adsorb multi-solute organophosphorus systems, and can selectively remove organophosphorus in complex water bodies with strong anti-interference ability. Brief Description of the Drawings
[0036] Figure 1 SEM images of Zr-Ce-MOF-808 loaded on plant fiber sponge prepared in Examples 1-3 of the present invention;
[0037] Figure 2 SEM images of Zr-La-MOFs loaded on D201 resin prepared in Examples 4-7 of the present invention;
[0038] Figure 3 Adsorption capacity schematic diagram of Zr-Ce-MOF-808@sponge prepared in Examples 1-3 of the present invention;
[0039] Figure 4 Adsorption capacity schematic diagram of Zr-La-MOFs@201 prepared in Examples 4-7 of the present invention;
[0040] Figure 5 Nitrogen adsorption and desorption isotherm of Zr-La-MOFs@201 prepared in Examples 4-7 of the present invention;
[0041] Figure 6 EPR spectra of the adsorbent materials prepared in Examples 1-3 and Comparative Example 1 of the present invention;
[0042] Figure 7 EPR spectra of Zr-La-MOFs@201 prepared in Examples 4-7 of the present invention;
[0043] Figure 8 Anti-interference performance schematic diagram of Zr-Ce-MOF-808@sponge prepared in Example 2 of the present invention;
[0044] Figure 9 Anti-interference performance schematic diagram of Zr-La-MOFs@201 prepared in Examples 4-7 of the present invention;
[0045] Figure 10 Adsorption cycle performance schematic diagram of Zr-Ce-MOF-808@sponge prepared in Example 2 of the present invention;
[0046] Figure 11Schematic diagram of the adsorption cycle performance of Zr-La-MOFs@201 prepared in Example 6 of the present invention;
[0047] Figure 12 Fourier transform infrared spectroscopy (FTIR) spectra of Zr-La-MOFs@201 before and after adsorption cycle prepared in Example 6 of the present invention. Detailed implementation manners
[0048] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0049] Example 1 - Preparation of Zr-Ce-MOF-808 supported plant fiber sponge adsorbent
[0050] Step 1: Dissolve 21.711 g (0.05 mol) of cerium nitrate hexahydrate and 16.11 g (0.05 mol) of zirconium oxychloride octahydrate in 180 mL of deionized water, then add 15 mL of ethanol and 5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0051] Step 2: Immerse 2 g of dry plant fiber sponge completely in the mixed solution for 12 h, and place the soaked plant fiber sponge in a vacuum drying oven at 60 °C for 12 h to obtain the precursor Zr-Ce@sponge.
[0052] Step 3: Dissolve 2.52 g of 1,3,5-benzenetricarboxylic acid in 60 mL of N,N-dimethylformamide solvent and transfer it to a polytetrafluoroethylene inner liner. Add the dried precursor Zr-Ce@sponge (the mass ratio of Zr-Ce@sponge to N,N-dimethylformamide solvent is 2:30), and immerse Zr-Ce@sponge in the prepared solution, and ultrasonicate for 30 min.
[0053] Step 4: Place the polytetrafluoroethylene inner liner in a reaction kettle and heat it at 120 °C for 24 h.
[0054] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 h to obtain the Zr-Ce-MOF-808 supported plant fiber sponge, namely Zr(1)-Ce(3)-MOF-808@sponge.
[0055] Example 2 - Preparation of Zr-Ce-MOF-808 Loaded Plant Fiber Sponge Adsorbent
[0056] Step 1: Dissolve 17.37 g (0.04 mol) of cerium nitrate hexahydrate and 22.55 g (0.07 mol) of zirconium oxychloride octahydrate (6.37 g) in 180 mL of deionized water, then add 15 mL of ethanol and 5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0057] Step 2: Completely immerse 2 g of dry plant fiber sponge into the mixed solution for 12 h, and place the immersed plant fiber sponge in a vacuum drying oven at 60 °C for 12 h to obtain the precursor Zr-Ce@sponge.
[0058] Step 3: Dissolve 2.52 g of 1,3,5-benzenetricarboxylic acid in 60 mL of N,N-dimethylformamide solvent and transfer it to a polytetrafluoroethylene inner liner. Add the dried precursor Zr-Ce@sponge (the mass ratio of Zr-Ce@sponge to N,N-dimethylformamide solvent is 2:30), and immerse Zr-Ce@sponge into the prepared solution, and ultrasonicate for 30 min.
[0059] Step 4: Place the polytetrafluoroethylene inner liner in a reaction kettle and heat it at 120 °C for 24 h.
[0060] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 h to obtain the Zr-Ce-MOF-808 loaded plant fiber sponge, namely Zr(3)-Ce(3)-MOF-808@sponge.
[0061] Example 3 - Preparation of Zr-Ce-MOF-808 Loaded Plant Fiber Sponge Adsorbent
[0062] Step 1: Dissolve 17.37 g (0.04 mol) of cerium nitrate hexahydrate and 32.21 g (0.1 mol) of zirconium oxychloride octahydrate (9.1 g) in 180 mL of deionized water, then add 15 mL of ethanol and 5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0063] Step 2: Completely immerse 2 g of dry plant fiber sponge into the mixed solution for 12 h, and place the immersed plant fiber sponge in a vacuum drying oven at 60 °C for 12 h to obtain the precursor Zr-Ce@sponge.
[0064] Step 3: Dissolve 2.52 g of 1,3,5-benzenetricarboxylic acid in 60 mL of N,N-dimethylformamide solvent, then transfer it to a polytetrafluoroethylene inner liner. Add the dried precursor Zr-Ce@sponge (the mass ratio of Zr-Ce@sponge to N,N-dimethylformamide solvent is 2:30), and immerse Zr-Ce@sponge in the prepared solution, followed by ultrasonic treatment for 30 min.
[0065] Step 4: Place the polytetrafluoroethylene inner liner in a reaction kettle and heat it at 120 °C for 24 h.
[0066] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 h to obtain the plant fiber sponge loaded with Zr-Ce-MOF-808, namely Zr(5)-Ce(3)-MOF-808@sponge.
[0067] Example 4—Preparation of Zr-La-MOFs Loaded D201 Resin Adsorbent
[0068] Step 1: Dissolve 8.056 g (0.025 mol) of zirconium oxychloride octahydrate and 32.475 g (0.075 mol) of lanthanum nitrate hexahydrate (10.425 g) in 192.5 mL of deionized water, then add 50 mL of ethanol and 7.5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0069] Step 2: Immerse 2 g of D201 resin microspheres completely in the mixed solution for 12 h, and place the soaked D201 resin in a vacuum drying oven at 60 °C for 12 h to obtain the precursor Zr-La@201.
[0070] Step 3: Dissolve 2.472 g of terephthalic acid in 60 mL of N,N-dimethylformamide solvent, then transfer it to a polytetrafluoroethylene inner liner. Add the dried precursor Zr-La@201 (the mass ratio of Zr-La@201 to N,N-dimethylformamide solvent is 1:30), and immerse Zr-La@201 in the prepared solution.
[0071] Step 4: Place the polytetrafluoroethylene inner liner in a reaction kettle and heat it at 120 °C for 24 h.
[0072] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 h to obtain the D201 resin loaded with Zr-La-MOFs, namely 1Zr-La-MOFs@201.
[0073] Example 5—Preparation of Zr-La-MOFs Loaded D201 Resin Adsorbent
[0074] Step 1: Dissolve 24.169 g (0.075 mol) of zirconium oxychloride octahydrate and 32.475 g (0.075 mol) of lanthanum nitrate hexahydrate (10.425 g) in 192.5 mL of deionized water. Then add 50 mL of ethanol and 7.5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0075] Step 2: Immerse 2 g of D201 resin microspheres completely into the mixed solution for 12 h. Place the soaked D201 resin in a vacuum drying oven at 60 °C and dry for 12 h to obtain the precursor Zr-La@201.
[0076] Step 3: Dissolve 2.472 g of terephthalic acid in 60 mL of N,N-dimethylformamide solvent and transfer it to a polytetrafluoroethylene inner liner. Add the dried precursor Zr-La@201 (the mass ratio of Zr-La@201 to N,N-dimethylformamide solvent is 1:30) to immerse Zr-La@201 into the prepared solution.
[0077] Step 4: Place the polytetrafluoroethylene inner liner in a reaction kettle and heat at 120 °C for 24 h.
[0078] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 h to obtain the D201 resin loaded with Zr-La-MOFs, namely 1.5Zr-La-MOFs@201.
[0079] Example 6 - Preparation of Zr-La-MOFs Loaded D201 Resin Adsorbent
[0080] Step 1: Dissolve 24.169 g (0.075 mol) of zirconium oxychloride octahydrate and 21.65 g (0.05 mol) of lanthanum nitrate hexahydrate (6.95 g) in 192.5 mL of deionized water. Then add 50 mL of ethanol and 7.5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0081] Step 2: Immerse 2 g of D201 resin microspheres completely into the mixed solution for 12 h. Place the soaked D201 resin in a vacuum drying oven at 60 °C and dry for 12 h to obtain the precursor Zr-La@201.
[0082] Step 3: Dissolve 2.472 g of terephthalic acid in 60 mL of N,N-dimethylformamide solvent and transfer it to a polytetrafluoroethylene inner liner. Add the dried precursor Zr-La@201 (the mass ratio of Zr-La@201 to N,N-dimethylformamide solvent is 1:30) to immerse Zr-La@201 into the prepared solution.
[0083] Step 4: Place the polytetrafluoroethylene inner container in the reaction kettle and heat it at 120 °C for 24 h.
[0084] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 h to obtain the D201 resin supported by Zr-La-MOFs, namely 2Zr-La-MOFs@201.
[0085] Example 7—Preparation of the adsorbent of D201 resin supported by Zr-La-MOFs
[0086] Step 1: Dissolve 32.225 g (0.1 mol) of zirconium oxychloride octahydrate and 32.475 g (0.075 mol) of lanthanum nitrate hexahydrate (10.425 g) in 192.5 mL of deionized water, then add 50 mL of ethanol and 7.5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0087] Step 2: Completely immerse 2 g of D201 resin microspheres in the mixed solution for 12 h, and place the soaked D201 resin in a vacuum drying oven at 60 °C for 12 h to obtain the precursor Zr-La@201.
[0088] Step 3: Dissolve 2.472 g of terephthalic acid in 60 mL of N,N-dimethylformamide solvent and transfer it to a polytetrafluoroethylene inner container. Add the dried precursor Zr-La@201 (the mass ratio of Zr-La@201 to N,N-dimethylformamide solvent is 1:30) to immerse Zr-La@201 in the prepared solution.
[0089] Step 4: Place the polytetrafluoroethylene inner container in the reaction kettle and heat it at 120 °C for 24 h.
[0090] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 h to obtain the D201 resin supported by Zr-La-MOFs, namely 2.5Zr-La-MOFs@201.
[0091] Comparative Example 1
[0092] Step 1: Dissolve 25.78 g (0.08 mol) of zirconium oxychloride octahydrate in 180 mL of deionized water, then add 15 mL of ethanol and 5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0093] Step 2: Completely immerse 2 g of dry plant fiber sponge in the solution for 12 h, and place the soaked plant fiber sponge in a vacuum drying oven at 60 °C for 12 h to obtain the precursor Zr@sponge.
[0094] Step 3: Dissolve 2.52 g of 1,3,5-benzenetricarboxylic acid in 60 mL of N,N-dimethylformamide solvent, then transfer it to a polytetrafluoroethylene inner liner. Add the dried precursor Zr@sponge and immerse Zr@sponge in the prepared solution, and ultrasonicate for 30 min.
[0095] Step 4: Place the polytetrafluoroethylene inner liner in a reaction kettle and heat at 120 °C for 24 h.
[0096] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, then dry it in a vacuum drying oven at 60 °C for 12 h to obtain plant fiber sponge loaded with Zr-MOF-808, namely Zr-MOF-808@sponge.
[0097] Comparative Example 2
[0098] Step 1: Dissolve 25.78 g (0.08 mol) of zirconium oxychloride octahydrate in 192.5 mL of deionized water, then add 50 mL of ethanol and 7.5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0099] Step 2: Completely immerse 2 g of D201 resin microspheres in the solution for 12 h. Place the soaked D201 resin in a vacuum drying oven at 60 °C and dry for 12 h to obtain the precursor Zr@201.
[0100] Step 3: Dissolve 2.472 g of terephthalic acid in 60 mL of N,N-dimethylformamide solvent, then transfer it to a polytetrafluoroethylene inner liner. Add the dried precursor Zr@201 and immerse Zr@201 in the prepared solution.
[0101] Step 4: Place the polytetrafluoroethylene inner liner in a reaction kettle and heat at 120 °C for 24 h.
[0102] Step 5: Wash the product three times with N,N-dimethylformamide and ethanol, then dry it in a vacuum drying oven at 60 °C for 12 h to obtain D201 resin loaded with UIO-66, namely UIO-66@201.
[0103] Comparative Example 3
[0104] Step 1: Dissolve 34.64 g (0.08 mol) of lanthanum nitrate hexahydrate in 192.5 mL of deionized water, then add 50 mL of ethanol and 7.5 mL of hydrochloric acid, and stir until completely dissolved to obtain a mixed solution.
[0105] Step 2: Completely immerse 2 g of D201 resin microspheres in the solution for 12 h. Place the soaked D201 resin in a vacuum drying oven at 60 °C and dry for 12 h to obtain the precursor La@201.
[0106] Step 3: Dissolve 2.472 g of terephthalic acid in 60 mL of N,N-dimethylformamide solvent and transfer to a polytetrafluoroethylene liner, add the dried precursor La@201, and immerse La@201 in the prepared solution.
[0107] Step 4: Place the polytetrafluoroethylene liner in a reactor and heat at 120°C for 24 hours.
[0108] Step 5: Wash the product with N,N-dimethylformamide and ethanol three times, and then dry it in a vacuum drying oven at 60° C. for 12 h to obtain La-BDC-loaded D201 resin, namely La-BDC@201.
[0109] Effect test:
[0110] (1) Image representation:
[0111] The bimetallic MOFs modified adsorbents prepared in Examples 1 to 7 were characterized.
[0112] The SEM images of Zr-Ce-MOF-808 prepared in Example 1-3 are as follows: Figure 1 As shown. Figure 1 It can be seen that Zr-Ce-MOF-808 is prismatic and evenly and densely dispersed inside the sponge. As the Zr loading increases, the bimetallic MOFs configuration changes from ordered to disordered. Some Zr-Ce-MOF-808 can no longer maintain a prismatic structure and mostly presents an irregular configuration with a smaller volume. When the mass fraction ratio of Zr metal to Ce metal reaches 5:3, it is almost impossible to observe the complete Zr-Ce-MOF-808.
[0113] The SEM images of Zr-La-MOFs@201 prepared in Example 4-7 are as follows: Figure 2 As shown. Figure 2 It can be seen that with the increase of Zr ratio, the size of these samples increased significantly and branches grew around, and the complete Zr-La-MOFs showed a bow-tie shape. When the Zr / La ratio exceeds 2, the overall structure of the MOF is no longer rod-shaped or bundle-shaped, but close to the octahedral shape of UIO-66. This phenomenon shows that when the Zr content is too high, the main structure of Zr-La-MOFs changes from La-BDC to UIO-66. Since the atomic radius of La is larger than that of Zr, the incorporation of La into the UIO 66 skeleton leads to the formation of multiple protruding particles on the surface of the structure.
[0114] (2) Test of adsorption and anti-interference performance:
[0115] The adsorbents prepared in Examples 1 to 7 and the comparative example were tested for their organic phosphine adsorption performance and anti-interference performance.
[0116] The adsorption experiment was carried out under the conditions of an adsorbent dosage of 0.5 g / L, a temperature of 298 K, an oscillation speed of 150 rpm, and an adsorption time of 12 h.
[0117] Comparing Examples 1 - 3, as Figure 3 shown, at different mass fraction ratios of Zr metal and Ce metal, Zr-Ce-MOF-808@sponge exhibited different adsorption performances for organophosphines. When the Zr / Ce ratio reached 3:3, that is, Zr(3)-Ce(3)-MOF-808@sponge had the maximum adsorption capacity for organophosphines, reaching 142.2 mg / g. This is because a certain degree of defect is beneficial to the exposure of metal active sites, and more active sites can enable the adsorbent to capture more organophosphines in a shorter time. This is also reflected in Zr-La-MOFs@201. Comparing Examples 4 - 7, as Figure 4 shown, the order of the maximum organophosphine adsorption capacity measured experimentally was 2-Zr-La-MOFs@201 (104.4 mg P / g) > 1.5-Zr-La-MOFs@201 (91.4 mgP / g) > 2.5-Zr-La-MOFs@201 (83.3 mg P / g) > 1-Zr-La-MOFs@201 (81.6 mg P / g). The results showed that there was a non-linear relationship between the metal loading and the adsorption capacity, and 2Zr-La-MOFs@201 exhibited the best adsorption performance. The adsorption performance of X-Zr-La-MOFs@201 for NTMP was affected by its different defect levels, specific surface area, and porosity. As Figure 5 shown, Zr-La-MOFs@201 showed a type III isotherm, which is characteristic of mesoporous materials. The mesopore range of 1-Zr-La-MOFs@201 was 3.0 - 7.0 nm, while that of 2.5-Zr-La-MOFs@201 was 3.0 - 14 nm.
[0118] Comparing Examples 1 - 7 and Comparative Example 1, as Figure 6 、 7 shown, the electron paramagnetic resonance spectra of the materials further reflected the defect situation inside the materials. The EPR spectra of Zr(1)-Ce(3)-MOF-808@sponge and 1-Zr-La-MOFs@201 showed some slight fluctuations, indicating that only some insignificant defects existed in the two materials at this stage. As the proportion of Zr gradually increased, the spectra showed obvious peaks near the g value of 2.003, indicating the presence of a large number of uncoupled metal centers. These metal centers acted as defects in the framework structure system, and with the increase of the Zr ratio, the level of defects also increased, indicating that more Zr in the framework was not well integrated.
[0119] At the same time, Examples 2 and 6 were used as adsorbents to test the anti-interference performance. Figure 8 The adsorption performance of Zr(3)-La(3)-MOF-808@sponge prepared in Example 2 in the presence of four anions is shown. It can be seen that among the four anions, sulfate ions interfere with the material most significantly. This is because sulfate and phosphate have similar chemical properties and stronger electronegativity, which makes it easier for sulfate to compete for vacant active sites. However, the material can still maintain an adsorption capacity of more than 92% at a sulfate ion concentration of 200 mg / L, further proving the practical application value of the material. Figure 9 The anti-sulfate interference performance of Zr-La-MOFs@201 was demonstrated, and at high concentrations of NTMP, the four materials showed slight differences. 2-Zr-La-MOFs@201 and 2.5-Zr-La-MOFs@201 performed better. This selectivity difference should be attributed to the exposure of the metal La center, which enhances sulfate insensitivity.
[0120] like Figure 10 , 11 As shown, Examples 2 and 6 used ethanol as the regeneration liquid to test the cyclic performance of the materials. Both materials showed good regeneration ability, and after 5 cycles, they could still maintain more than 90% of the maximum adsorption capacity.
[0121] Figure 12 The infrared spectra of Zr-La-MOFs@201 before and after adsorption and regeneration are shown, in which the 749 cm -1 The OH peak at is significantly restored, indicating that the material has good recyclability.
[0122] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.
Claims
1. A method for preparing a tunable defective bimetallic MOFs modified adsorbent, characterized in that: include: S1. Dissolving zirconium salt and rare earth element salt in water, adding hydrochloric acid and ethanol to obtain a mixed solution; S2, adding a carrier to the mixed solution for soaking, filtering and drying to obtain a precursor; S3, dissolving the organic ligand in N,N-dimethylformamide, adding the precursor obtained in step S2, and performing a hydrothermal reaction. After the reaction is completed, a bimetallic MOFs modified adsorbent is obtained.
2. The method for preparing a controllable defective bimetallic MOFs modified adsorbent according to claim 1, characterized in that: In step S1, the rare earth element salt is a cerium salt; The mass ratio of the zirconium salt to the cerium salt is 1-9:2-6. The zirconium salt is zirconium oxychloride octahydrate or zirconium chloride, and the cerium salt is cerium nitrate hexahydrate or ammonium cerium nitrate.
3. The method for preparing a tunable defect bimetallic MOFs modified adsorbent according to claim 2, characterized in that: In step S1, the concentration of zirconium salt in the mixed solution is 0.027 mol / L-0.25 mol / L, the concentration of cerium salt is 0.046 mol / L-0.14 mol / L, the concentration of hydrochloric acid is 1.5-5 wt%, and the concentration of ethanol is 5-25 wt%.
4. The method for preparing a controllable defective bimetallic MOFs modified adsorbent according to claim 2, characterized in that: In step S2, the carrier is a plant fiber sponge; In step S3, the organic ligand is 1,3,5-benzenetricarboxylic acid.
5. The method for preparing a controllable defective bimetallic MOFs modified adsorbent according to claim 4, characterized in that: The step S3 is specifically as follows: After 1,3,5-benzenetricarboxylic acid was dissolved in N,N-dimethylformamide, the precursor was added for ultrasonic dispersion, followed by hydrothermal reaction. After the hydrothermal reaction was completed, the mixture was filtered, washed and dried to obtain the bimetallic MOFs modified adsorbent Zr-Ce-MOF-808@sponge. The mass ratio of the precursor, N,N-dimethylformamide and 1,3,5-benzenetricarboxylic acid is 2:30:1-3; The ultrasonic dispersion time is 30-50 min; the hydrothermal reaction temperature is 120°C, and the hydrothermal reaction time is 24 h; The washing process is as follows: washing with N, N-dimethylformamide and ethanol solution 3-5 times; The drying temperature is 60°C and the drying time is 8-12h.
6. The method for preparing a tunable defect bimetallic MOFs modified adsorbent according to claim 1, characterized in that: In step S1, the rare earth element salt is a lanthanum salt; The mass ratio of the zirconium salt to the lanthanum salt is 1-13:2-7; The zirconium salt is zirconium oxychloride octahydrate or zirconium chloride, and the lanthanum salt is lanthanum nitrate hexahydrate or lanthanum chloride.
7. The method for preparing a controllable defective bimetallic MOFs modified adsorbent according to claim 6, characterized in that: In step S1, the concentration of zirconium salt in the mixed solution is 0.027 mol / L-0.36 mol / L, the concentration of lanthanum salt is 0.046 mol / L-0.16 mol / L, the concentration of hydrochloric acid is 1.5-5 wt%, and the concentration of ethanol is 5-25 wt%.
8. The method for preparing a controllable defective bimetallic MOFs modified adsorbent according to claim 6, characterized in that: In step S2, the carrier is D201 resin; In step S3, the organic ligand is terephthalic acid.
9. The method for preparing a controllable defective bimetallic MOFs modified adsorbent according to claim 8, characterized in that: The step S3 is specifically as follows: After dissolving terephthalic acid in N, N-dimethylformamide, the precursor is added to carry out a hydrothermal reaction, and after the hydrothermal reaction is completed, the mixture is filtered, washed and dried to obtain a bimetallic MOFs modified adsorbent Zr-La-MOFs@201; Wherein, the mass ratio of the precursor, N,N-dimethylformamide and terephthalic acid is 1:30:1-3; The hydrothermal reaction temperature is 120°C and the hydrothermal reaction time is 24h; The washing process is as follows: washing with N, N-dimethylformamide and ethanol solution 3-5 times; The drying temperature is 60°C and the drying time is 8-12h.
10. Use of the controllable defective bimetallic MOFs modified adsorbent prepared by the method according to any one of claims 1 to 9 in the adsorption of aminotrimethylenephosphonic acid.