Diphosphonic acid modified metal organic framework material as well as preparation and application thereof

Abstract

The invention relates to the technical field of adsorption materials, in particular to a diphosphonic acid modified metal organic framework material as well as preparation and application thereof. The material is prepared by carrying out acylation reaction on UiO-66-NH2 and N, N-bis (phosphine hydroxymethyl) glycine. The preparation method comprises the following steps: S1, carrying out ultrasonic dispersion on UiO-66-NH2 in an organic solvent, so as to obtain a UiO-66-NH2 suspension; and S2, adding N, N '-dicyclohexylcarbodiimide and N, N-bis (phosphine hydroxymethyl) glycine into the UiO-66-NH2 suspension, carrying out heating reflux, carrying out acylation reaction, cooling, carrying out centrifugal separation, washing and drying to obtain the diphosphonic acid modified metal organic framework material. The material has a more stable structure, a larger pore structure, richer adsorption sites and larger adsorption capacity, and has excellent adsorption performance on neodymium ions in a water body.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption materials, and particularly to a bisphosphonic acid group modified metal-organic framework material and its preparation and application. Background Art

[0002] Rare earth elements (REEs) are a group of high-value metals with increasing demand and wide applications. Among them, neodymium is widely used in new energy technologies, electronic products, permanent magnets, etc. due to its unique properties, and is considered one of the five most critical rare earth elements. Since the reserves of rare earth minerals are limited and non-renewable, in order to ensure the uninterrupted supply of rare earth elements, it is of great significance to recover them from various secondary resources including industrial and urban wastes in terms of environmental protection and resource recycling. Currently, a variety of rare earth element extraction methods have been developed, and the most common method is solvent extraction, but organic extractants are prone to cause secondary pollution to the environment. To avoid the above problems, many new extraction methods, such as ion exchange method, electrochemical method and adsorption, have emerged. Among these current technologies, the adsorption method is considered a mature and environmentally friendly rare earth element recovery process, with the characteristics of simple operation, low cost, sustainability and environmental protection and high efficiency. Traditional solid adsorption materials have serious defects in repeated utilization in the acid leaching solution of secondary resources. Summary of the Invention

[0003] The purpose of the present invention is to propose a bisphosphonic acid group modified metal-organic framework material and its preparation and application in view of the above deficiencies of the prior art.

[0004] The first object of the present invention is to provide a bisphosphonic acid group modified metal-organic framework material, which is prepared by an acylation reaction of UiO-66-NH2 and N,N-bis(phosphonomethyl)glycine.

[0005] The second object of the present invention is to provide a preparation method of the bisphosphonic acid group modified metal-organic framework material as described above, including the following steps:

[0006] S1. Ultrasonically disperse UiO-66-NH2 in N,N-dimethylformamide to obtain a UiO-66-NH2 suspension;

[0007] S2. Add N,N'-dicyclohexylcarbodiimide and N,N-bis(phosphonomethyl)glycine to the above UiO-66-NH2 suspension, heat under reflux for an acylation reaction, and after cooling, centrifuge and separate, wash and dry to obtain the bisphosphonic acid group modified metal-organic framework material.

[0008] Furthermore, the mass concentration of the UiO-66-NH2 suspension is 20 g / L to 100 g / L.

[0009] Further, the molar ratio of N,N-bis(phosphonomethyl)glycine to N,N'-dicyclohexylcarbodiimide is 1:1 to 2.

[0010] Further, in step S1, the organic solvent is N,N-dimethylformamide; in step S2, washing is carried out using absolute ethanol or absolute methanol.

[0011] Further, UiO-66-NH2 is prepared by the following preparation method:

[0012] 1) Dissolve zirconium tetrachloride in N,N-dimethylformamide, and then add acetic acid to the mixture and ultrasonicate at room temperature;

[0013] 2) Add 2-aminoterephthalic acid and DMF to the above ultrasonified solution, ultrasonicate for a period of time, and then carry out a hydrothermal reaction;

[0014] 3) Separate the above mixed reaction slurry, and wash and dry the obtained solid to obtain amino-containing MOFs.

[0015] Further, in step 1), the concentration of the mixture is 0.3 to 0.4 mol / L, and the volume ratio of the mixture to acetic acid is 6:3 to 5;

[0016] Further, in step 2), the volume ratio of the ultrasonified solution to DMF is 5:6 to 8.

[0017] Further, in step 3), the organic detergent is DMF and absolute methanol.

[0018] The third object of the present invention is to provide an application of the above-mentioned bisphosphonic acid group-modified metal-organic framework material for adsorbing neodymium ions in a solution.

[0019] The bisphosphonic acid group-modified metal-organic framework material of the present invention uses the metal-organic framework UiO-66-NH2 with a large specific surface area and acid and high-temperature resistance as the matrix. After the surface undergoes an acylation reaction between N,N-bis(phosphonomethyl)glycine and amino groups, rich phosphonic acid groups are formed. The phosphonic acid groups are adsorption functional monomers that coordinate and chelate with rare metal ions, increasing the number and density of phosphonic acid groups on the surface of the composite material and the coordination and chelation ability with neodymium ions, and significantly increasing the adsorption sites.

[0020] The bisphosphonate group-modified metal-organic framework material of the present invention has a more stable structure, a larger pore structure, richer adsorption sites, a larger adsorption capacity, excellent adsorption performance for neodymium ions in water, strong affinity for neodymium ions in a complex environment, and can quickly reach adsorption equilibrium, greatly improving the adsorption efficiency of neodymium ions in the acid leaching solution of secondary resources. It is used to adsorb and recover neodymium ions in the acid leaching solution of secondary resources, and the adsorption capacity for neodymium ions is 108.10 - 124.99 mg / g, and can be recycled by elution. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic flow chart of the preparation method of the bisphosphonate group-modified metal-organic framework material in the embodiment of the present invention;

[0022] Figure 2 It is an SEM spectrum of the bisphosphonate group-modified metal-organic framework material prepared in Example 1 of the present invention;

[0023] Figure 3 It is an infrared spectrum of the bisphosphonate group-modified metal-organic framework material prepared in Example 1 of the present invention;

[0024] Figure 4 It is an adsorption effect and Zeta potential diagram of the bisphosphonate group-modified metal-organic framework material prepared in Example 1 under different pH conditions;

[0025] Figure 5 It is an adsorption schematic diagram of the bisphosphonate group-modified metal-organic framework material prepared in Example 1 for neodymium ions at different times;

[0026] Figure 6 It is an adsorption effect schematic diagram of the bisphosphonate group-modified metal-organic framework material prepared in Example 1 for neodymium ions under different high-salt systems. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following are specific embodiments of the present invention in combination with the drawings, and the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0028] Example 1

[0029] A preparation method of a bisphosphonate group-modified metal-organic framework material, as Figure 1 shown, includes the following steps:

[0030] 1) Take a certain proportion of zirconium tetrachloride and 2-amino-1,4-benzenedicarboxylic acid and ultrasonically disperse them in N,N-dimethylformamide, and add a certain mass of acetic acid solution to prepare a mixed solution. The molar ratio of the zirconium tetrachloride to the 2-amino-1,4-benzenedicarboxylic acid is 1:1. The volume fraction of the acetic acid solution is 10%.

[0031] 2) Transfer the above solution to a polytetrafluoroethylene-lined reactor and carry out hydrothermal reaction at 120 °C for 24 h.

[0032] 3) Centrifuge the above mixed reaction slurry. After the obtained solid is washed three times with the organic detergent N,N-dimethylformamide and absolute ethanol, it is dried at 100 °C for 10 hours to obtain the metal-organic framework material, denoted as UiO-66-NH2.

[0033] 4) Ultrasonically disperse a certain amount of the obtained UiO-66-NH2 in an appropriate amount of N,N-dimethylformamide to obtain a 20 g / L UiO-66-NH2 suspension.

[0034] 5) Add N,N'-dicyclohexylcarbodiimide and N,N-bis(phosphonomethyl)glycine in a certain mass ratio to the above UiO-66-NH2 suspension, heat under reflux at 160 °C, and carry out acylation reaction for 48 hours. The molar ratio of bis(phosphonomethyl)glycine to N,N'-dicyclohexylcarbodiimide is 1:1.33.

[0035] 6) Cool the above mixed reaction slurry to room temperature and then centrifuge it. After the obtained solid is washed three times with the alcohol washing agent absolute methanol, it is dried at 100 °C for 10 hours to obtain the composite functional material of bisphosphonic acid group ligand modified UiO-66-NH2, denoted as BPG@UiO-66-NH2.

[0036] Figure 2 SEM pattern of the bisphosphonic acid group modified metal-organic framework material prepared in Example 1 of the present invention; from Figure 2 it can be seen that BPG@UiO-66-NH2 has a good microstructure, the particles are spherical-like, the microscopic surface is rough, and the molecules show a clustered state;

[0037] Figure 3 IR spectrum of the bisphosphonic acid group modified metal-organic framework material prepared in Example 1 of the present invention; from Figure 3 it can be seen that for BPG@UiO-66-NH2, the stretching vibration peak of the -P=O bond is at 1151 cm -1 , and the stretching vibration peaks corresponding to the -P-OH bond are at 2474 cm -1 and 1022 cm -1 ; both belong to the bisphosphonic acid group in the BPG ligand;

[0038] Application Example 1

[0039] 6 mg of the bisphosphonate group-modified metal-organic framework material of Example 1 was respectively taken and placed in 20 mL of a neodymium ion solution with a concentration of 50 mg / L prepared from neodymium nitrate hexahydrate, with the pH range of 2 - 6. The reaction was carried out at 25 °C for 24 hours. The concentration of neodymium ions in the solution after adsorption was measured using an ultraviolet spectrophotometer, and the maximum absorption wavelength was 660 nm.

[0040] Figure 4 The adsorption effect and Zeta potential diagram of the bisphosphonate group-modified metal-organic framework material of the examples of the present invention under different pH conditions are as Figure 4 shown. The adsorption effect is the best when the pH is 4 - 6; and the adsorption capacity for neodymium ions is 124.99 mg / g after adsorption at room temperature for 24 hours.

[0041] Application Example 2

[0042] 6 mg of the bisphosphonate group-modified metal-organic framework material of Example 1 was respectively taken and placed in 20 mL of a neodymium ion solution with a concentration of 50 mg / L and a pH of 5. The reaction was carried out at 25 °C. As the adsorption reaction proceeded, the concentration of neodymium ions in the solution was measured at different times, and the adsorption capacity of the composite material for neodymium ions was calculated.

[0043] Refer to the attached Figure 5 . The adsorption of neodymium ions by the bisphosphonate group-modified metal-organic framework material prepared by the preparation method of Example 1 proceeded relatively fast in the first 5 minutes and reached adsorption saturation after 10 minutes. The adsorption capacity of the bisphosphonate group-modified metal-organic framework material prepared in Example 1 for neodymium ions is 124.99 mg / g.

[0044] Application Example 3

[0045] 6 mg of the bisphosphonate group-modified metal-organic framework material of Example 1 was respectively taken and placed in 20 mL of 0.5 M Na2SO4 containing 50 mg / L neodymium ions, 20 mL of 1 M Na2SO4 containing 50 mg / L neodymium ions, 20 mL of 0.5 M NaCl containing 50 mg / L neodymium ions, 20 mL of 1 M NaCl containing 50 mg / L neodymium ions, 20 mL of 0.5 M NaNO3 containing 50 mg / L neodymium ions, and 20 mL of 1 M NaNO3 containing 50 mg / L neodymium ions in high-salt system solutions. The pH was 5, and the adsorption reaction was carried out at 25 °C. After adsorption equilibrium, the concentration of neodymium ions in the solution after adsorption was measured using an ultraviolet spectrophotometer, and the maximum absorption wavelength was 660 nm. The adsorption capacity of the composite material for neodymium ions was calculated to investigate the influence of the high-salt system on the adsorption of neodymium ions.

[0046] Refer to the attached Figure 6 . During the adsorption process of the bisphosphonate group-modified metal-organic framework material of Example 1 in high-salt systems with different components, the adsorption rate of neodymium remained above 90%, showing good anti-interference ability for neodymium adsorption.

[0047] Application Example 4

[0048] Take the phosphonic acid group modified metal-organic framework material that has been saturated with adsorption in the above application example and elute it with 1 mol / L HNO3 solution until no neodymium ions can be detected in the eluent, then dry it and calcine it for the next adsorption. Adsorption conditions: dosage 6 mg, in 20 mL of neodymium ion solution with a concentration of 50 mg / L, pH is 5, and the adsorption reaction is carried out at 25 °C for 10 minutes. After the phosphonic acid group modified metal-organic framework material reaches adsorption saturation, continue to elute it with 1 mol / L HNO3 solution. After repeating the adsorption-desorption 5 times, the adsorption capacity is 109.38 mg / g, indicating that the phosphonic acid group modified metal-organic framework material prepared in Example 1 of the present invention has good stability and renewable performance.

[0049] For those not covered above, the prior art shall apply.

[0050] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the technical field to which the present invention pertains can make various modifications or supplements to the specific embodiments described or substitute them in a similar manner, but will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall be included within the protection scope of the present invention.

Claims

1. A metal-organic framework material modified with bisphosphonic acid groups, characterized in that, It is prepared by the acylation reaction of UiO-66-NH2 and N,N-bis(phosphonomethyl)glycine.

2. A method for preparing a bisphosphonic acid group-modified metal-organic framework material as described in claim 1, characterized in that, It includes the following steps: S1. Ultrasonically disperse UiO-66-NH2 in an organic solvent to obtain a UiO-66-NH2 suspension; S2. Add N,N'-dicyclohexylcarbodiimide and N,N-bis(phosphonomethyl)glycine to the above-mentioned UiO-66-NH2 suspension, heat under reflux for acylation reaction, centrifuge and separate after cooling, wash and dry to obtain a bisphosphonic acid group-modified metal-organic framework material.

3. The preparation method according to claim 2, characterized in that, The mass concentration of the UiO-66-NH2 suspension is 20 g / L to 100 g / L.

4. The preparation method according to claim 2, characterized in that, The molar ratio of N,N-bis(phosphonomethyl)glycine to N,N'-dicyclohexylcarbodiimide is 1:1 to 2.

5. The preparation method according to claim 2, characterized in that, In step S1, the organic solvent is N,N-dimethylformamide; in step S2, washing is carried out with absolute ethanol or absolute methanol.

6. The preparation method according to claim 2, wherein, UiO-66-NH2 is prepared by the following preparation method: 1) Dissolve zirconium tetrachloride in N,N-dimethylformamide, and then add acetic acid to the mixed solution, and ultrasonicate at room temperature; 2) Add 2-aminoterephthalic acid and DMF to the above ultrasonically treated solution, ultrasonicate for a period of time, and then carry out a hydrothermal reaction; 3) Separate the above mixed reaction slurry, and wash and dry the obtained solid to obtain an amino-containing MOF.

7. The preparation method according to claim 2, wherein In step 1), the concentration of the mixed solution is 0.3 to 0.4 mol / L, and the volume ratio of the mixed solution to acetic acid is 6:3 to 5.

8. The preparation method according to claim 2, characterized in that, In step 2), the volume ratio of the ultrasonically treated solution to DMF is 5:6 to 8.

9. The preparation method according to claim 2, characterized in that, In step 3), the organic detergent is DMF and absolute methanol.

10. Use of the bisphosphonic acid group-modified metal-organic framework material according to claim 1, characterized in that: It is used to adsorb neodymium ions in the solution.

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