Porous metal organic framework derivative material for adsorbing rare earth metal ions as well as preparation method and application of porous metal organic framework derivative material

Abstract

The invention discloses a porous metal organic framework derivative material for adsorbing rare earth metal ions as well as a preparation method and application of the porous metal organic framework derivative material, and belongs to the technical field of rare earth metal ion adsorption and removal. The porous metal organic framework derivative material for adsorbing rare earth metal ions comprises a porous metal organic framework and small organic molecules grafted on the porous metal organic framework. The porous metal organic framework derivative material provided by the invention has excellent rare earth metal ion adsorption property. Therefore, the porous metal organic framework derivative material can be constructed into a miniature capturer to be applied to adsorption and removal of rare earth metal ions in a water environment.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth metal ion adsorption, and in particular to a porous metal organic framework derivative material for adsorbing rare earth metal ions, and a preparation method and application thereof. Background Art

[0002] Freshwater resources are the foundation for human survival and development. In order to solve the problem of rare earth metal ion pollution caused by the discharge of industrial wastewater and nuclear wastewater, methods including removal, fixation and recovery have been developed, such as adsorption, membrane separation, precipitation, electrochemical treatment, ion exchange and biological methods. Among them, the adsorption method has a good effect on the treatment of rare earth metal ions in the water environment. The materials used are green and environmentally friendly, low cost, and flexible designability. It is currently the most chosen method for scientific researchers to remove rare earth metal ions from water. However, traditional adsorbents have problems such as poor adsorption effect, single removal object, and difficult recovery. Therefore, the development of new adsorbents with multiple adsorption sites, strong universality and easy recovery performance is of great significance for treating the problem of rare earth metal ion pollution caused by industrial wastewater and nuclear wastewater. Summary of the invention

[0003] The purpose of the present invention is to provide a porous metal organic framework derivative material for adsorbing rare earth metal ions and its preparation method and application, so as to solve the problems existing in the above-mentioned prior art. The porous metal organic framework derivative material designed by the present invention can remove almost all lanthanide rare earth elements at the same time, solving the problems of the existing adsorption materials with single adsorption object, poor recovery ability and few adsorption sites.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention: a porous metal organic framework derivative material for adsorbing rare earth metal ions, comprising a porous metal organic framework and organic small molecules grafted (grafting specifically refers to replacing -COOH on the metal organic framework with groups on the organic small molecules) on the porous metal organic framework.

[0006] Furthermore, the porous metal organic framework is MOF 808 (MOF 808 has a larger pore size and a larger specific surface area, and the -COOH on the Zr6 cluster (zirconium oxygen cluster) is easily replaced by an organic small molecule with -COOH to achieve the functionalization of MOF 808).

[0007] Furthermore, the organic small molecule is 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA, one molecule of PBTCA carries 3 -COOH groups which can replace the -COOH groups on the Zr6 cluster to achieve the purpose of grafting, and PBTCA contains abundant unsaturated coordination sites which can adsorb rare earth metal ions well).

[0008] Furthermore, the preparation method of the MOF 808 includes: dissolving 1,3,5-benzenetricarboxylic acid and a Zr source in a mixed solution of DMF (N,N-dimethylformamide) and formic acid, heating for reaction, and then centrifuging, washing, and drying to obtain the MOF808.

[0009] Furthermore, the Zr source is ZrOCl2·8H2O, the volume ratio of DMF and formic acid in the mixed solution is 1:1; the dosage ratio of the 1,3,5-benzenetricarboxylic acid, ZrOCl2·8H2O and the mixed solution of DMF and formic acid is 0.21g:0.97g:60mL.

[0010] Furthermore, the heating reaction is carried out at a temperature of 100° C. and for 24 hours.

[0011] Furthermore, the specific operation of washing is: washing the precipitate collected by centrifugation three times with DMF within 24 hours, and then washing it three times with acetone within 24 hours.

[0012] Furthermore, the specific surface area of ​​MOF 808 is 1183.94 m 2 / g, and the average pore size is 1.8nm.

[0013] The second technical solution of the present invention: The preparation method of the porous metal organic framework derivative material for adsorbing rare earth metal ions comprises the following steps:

[0014] The organic small molecule is added dropwise to the dispersion of the porous metal organic framework, and stirred continuously at room temperature (the organic small molecule is grafted into the porous metal organic framework during the stirring process) to obtain the porous metal organic framework derivative material for adsorbing rare earth metal ions (or the porous metal organic framework derivative material grafted with organic small molecules, referred to as MOF 808-PBTCA for short).

[0015] Furthermore, the mass ratio of the organic small molecules to the porous metal organic framework is 3:100.

[0016] Furthermore, the continuous stirring time is 20 hours.

[0017] Furthermore, after the continuous stirring is completed, the powder is collected by centrifugation, and the collected powder is immersed in ultrapure water for washing three times within 24 hours, and then washed three times with acetone within 24 hours.

[0018] The third technical solution of the present invention: Application of the above-mentioned porous metal organic framework derivative material for adsorbing rare earth metal ions in the adsorption of rare earth metal ions.

[0019] Furthermore, the rare earth metal ions are lanthanide rare earth metal ions.

[0020] The present invention obtains a porous metal organic framework derivative material grafted with organic small molecules by grafting them into MOF. The porous metal organic framework derivative material is a new type of rare earth metal ion adsorbent, and the porous metal organic framework derivative material can be constructed into a micro-capture device for adsorption and removal of rare earth metal ions in water environments. It has the characteristics of multiple adsorption sites, strong universality, and easy recycling. By utilizing the interaction between the organic small molecules grafted on MOF and the rare earth metal ions, the rare earth ions in the water environment can be efficiently removed.

[0021] Porous metal-organic framework-derived materials grafted with organic small molecules not only maintain the original characteristics of porous metal-organic frameworks such as large specific surface area, high porosity, and controllable structure, but also enrich abundant adsorption sites in the pores, which can be used in the capture and transportation, adsorption and separation, storage and release of some substances.

[0022] The present invention discloses the following technical effects:

[0023] (1) The porous metal organic framework derivative material (porous metal organic framework derivative material grafted with organic small molecules) prepared by the present invention for adsorbing rare earth metal ions has strong rare earth metal ion adsorption performance and can achieve rapid adsorption of rare earth metal ions at room temperature.

[0024] (2) The porous metal organic framework derivative material for rare earth metal ion adsorption prepared by the present invention has the advantages of high crystallinity, complete morphology, porous structure, large specific surface area, fast adsorption speed, large adsorption amount, good stability (its structure will not be destroyed after adsorption of rare earth elements), strong anti-interference ability, etc., and can realize the adsorption and removal of rare earth metal ions in industrial wastewater and nuclear wastewater.

[0025] (3) The porous metal organic framework derivative material for adsorbing rare earth metal ions prepared by the present invention can reach adsorption equilibrium within 15 minutes when adsorbing rare earth metal ions in water, and can also achieve rapid adsorption in a low concentration rare earth metal ion environment.

[0026] (4) The synthetic route of the present invention is simple and feasible, the reaction conditions are mild and controllable, the product yield is high and the stability is good, the cost is low, and it is suitable for large-scale use. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 TEM and EDS element distribution diagram of the raw material MOF 808 in the present invention;

[0029] Figure 2 TEM and EDS element distribution diagram of MOF 808-PBTCA prepared in Example 1 of the present invention;

[0030] Figure 3 TEM and EDS element distribution diagram of MOF 808-PBTCA@Ce obtained in Application Example 1 of the present invention;

[0031] Figure 4 TEM and EDS element distribution diagram of MOF 808-PBTCA@Eu obtained in Application Example 2 of the present invention;

[0032] Figure 5 TEM and EDS element distribution diagram of MOF 808-PBTCA@Nd obtained in Application Example 3 of the present invention;

[0033] Figure 6 XRD patterns of the raw material MOF 808, MOF 808-PBTCA prepared in Example 1, and MOF 808-PBTCA@Ce, MOF 808-PBTCA@Eu, and MOF 808-PBTCA@Nd after adsorbing rare earth metal ions in Application Examples 1-3;

[0034] Figure 7 FT-IR images of the raw material MOF 808, MOF 808-PBTCA prepared in Example 1, and MOF 808-PBTCA@Ce, MOF 808-PBTCA@Eu, and MOF 808-PBTCA@Nd after adsorbing rare earth metal ions in Application Examples 1-3;

[0035] Figure 8 H NMR spectra of raw material MOF 808 (a) and MOF 808-PBTCA (b) prepared in Example 1;

[0036] Fig. 9 FT-IR images of ZIF 8 prepared in Comparative Example 2 and ZIF 8 grafted with PBTCA;

[0037] Fig.10 N2 adsorption-desorption isotherms (a) and pore size distribution diagram (b) of MOF 808, MOF 808-PBTCA prepared in Example 1, and MOF 808-PBTCA@Ce, MOF 808-PBTCA@Eu, and MOF 808-PBTCA@Nd after adsorbing rare earth metal ions in Application Examples 1-3;

[0038] Fig.11 This is a relationship diagram between the adsorption efficiency and adsorption time of MOF 808-PBTCA prepared in Example 1 during the adsorption of Ce, Eu, and Nd;

[0039] Fig.12 This is a diagram showing the adsorption efficiency of MOF 808-PBTCA prepared in Example 1 in a mixed system of transition metal ions and rare earth ions. DETAILED DESCRIPTION

[0040] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0041] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0042] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0043] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0044] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0045] The yield in the specific implementation manner of the present invention is calculated as follows: the mass of the dried product / the sum of the masses of the raw materials×100%.

[0046] In the specific implementation of the present invention, the calculation method of the adsorption efficiency of the adsorption material for rare earth metal ions is: the difference in the content of rare earth ions in the solution before and after adsorption / the content of rare earth ions in the solution before adsorption×100%.

[0047] In the specific implementation manner of the present invention, the method for calculating the adsorption amount of rare earth metal ions by the adsorption material is: the difference in the content of rare earth ions in the solution before and after adsorption / the amount of adsorption material×100%.

[0048] The room temperature involved in the specific implementation manner of the present invention specifically refers to 20-30°C.

[0049] The preparation method of MOF 808 used in the specific embodiment of the present invention is as follows: in a 100 mL flask, 1,3,5-benzenetricarboxylic acid (0.21 g) and ZrOCl2·8H2O (0.97 g, purity 98%) are dissolved in a mixed solution of 60 mL DMF and formic acid (30 mL DMF + 30 mL formic acid), the flask is sealed and heated in a constant temperature oven at 100°C for 24 hours, white powder is collected by centrifugation (8000 rpm, 3 min), washed three times with DMF within 24 hours, and then washed three times with acetone within 24 hours, and finally dried in a vacuum oven at 30°C to obtain MOF 808. The TEM and EDS element distribution diagrams of the prepared MOF 808 are shown in Figure 1 , XRD pattern see Figure 6 , FT-IR diagram see Figure 7 .

[0050] Except MOF 808, other raw materials are common commercial products.

[0051] Example 1

[0052] A method for preparing a porous metal organic framework derivative material, comprising the following steps:

[0053] (1) Weigh 50 mg of MOF 808 and add it into 50 mL of ultrapure water. Ultrasonic treatment is performed for 5 min to make MOF 808 disperse evenly to obtain a MOF 808 dispersion.

[0054] (2) Add 1.5 mg of PBTCA to the dispersion of MOF 808 obtained in step (1), continue stirring at room temperature for 20 hours, collect the powder by centrifugation, soak the collected powder in ultrapure water for 24 hours and wash it three times, then wash it with acetone for 3 times within 24 hours, and dry it to obtain a PBTCA-grafted porous metal-organic framework derivative material (MOF 808-PBTCA). MOF808-PBTCA is a white powder with a yield of 97.4% and a purity of 99%.

[0055] Application Example 1

[0056] Weigh 10 mg of CeCl3 and dissolve it in 10 mL of ultrapure water to obtain a 1 mg / mL CeCl3 solution (repeat the above process to prepare two CeCl3 solutions of equal concentration and volume, and use inductively coupled plasma to detect the Ce content of the solution). 3+ 20 mg of MOF 808-PBTCA prepared in Example 1 and 20 mg of raw material MOF 808 (as a control) were weighed and dispersed into the above two CeCl3 solutions, stirred at room temperature for 20 min, and centrifuged to obtain a supernatant and a residue (the residue with MOF 808-PBTCA added was Ce adsorbed). 3+ The supernatant of the group with MOF 808-PBTCA and the group with MOF 808 were taken, and the Ce in the supernatant was detected by inductively coupled plasma (ICP-AES). 3+ According to the Ce content in the supernatant after adsorption 3+ The content of Ce in the solution before adsorption 3+ The effects of MOF 808-PBTCA and MOF 808 on Ce were calculated based on the content of MOF808-PBTCA or MOF 808. 3+ The adsorption capacities of MOF 808-PBTCA prepared in Example 1 were 496 mg / g and 115.5 mg / g respectively; the adsorption efficiencies were 99.2% and 23.1% respectively. 3+ The adsorption effect is good.

[0057] Application Example 2

[0058] Weigh 10 mg of Eu(NO3)3 and dissolve it in 10 mL of ultrapure water to obtain a 1 mg / mL Eu(NO3)3 solution (2 portions); weigh 20 mg of MOF 808-PBTCA prepared in Example 1 and 20 mg of raw material MOF 808 (as a control) and disperse them in the above two portions of Eu(NO3)3 solution, stir at room temperature for 20 min, and centrifuge to obtain a supernatant and a residue (the residue with MOF 808-PBTCA added is the residue adsorbed with Eu). 3+ The supernatant of the group with MOF808-PBTCA added and the supernatant of the group with MOF808 added were taken, and the Eu in the supernatant was detected by inductively coupled plasma. 3+ According to the content of Eu in the supernatant after adsorption 3+ The content of Eu in the solution before adsorption 3+ The effects of MOF 808-PBTCA and MOF 808 on Eu were calculated based on the content of MOF 808-PBTCA or MOF 808. 3+ The adsorption capacities of MOF 808-PBTCA prepared in Example 1 were 491.5 mg / g and 113 mg / g respectively; the adsorption efficiencies were 98.3% and 22.6% respectively. 3+ The adsorption effect is good.

[0059] Application Example 3

[0060] Weigh 10 mg of Nd(NO3)3 and dissolve it in 10 mL of ultrapure water to obtain a 1 mg / mL Nd(NO3)3 solution (2 portions); weigh 20 mg of MOF 808-PBTCA prepared in Example 1 and 20 mg of raw material MOF 808 (as a control) and disperse them in the above two portions of Nd(NO3)3 solution, stir at room temperature for 20 min, and centrifuge to obtain a supernatant and a residue (the residue added with MOF 808-PBTCA is the residue adsorbed with Nd 3+ The supernatant of the group with MOF808-PBTCA added and the group with MOF808 added were taken, and the Nd in the supernatant was detected by inductively coupled plasma. 3+ According to the content of Nd in the supernatant after adsorption 3+ The content of Nd in the solution before adsorption 3+ The effects of MOF 808-PBTCA and MOF 808 on Nd 3+The adsorption capacities of MOF 808-PBTCA prepared in Example 1 were 494.5 mg / g and 109.5 mg / g respectively; the adsorption efficiencies were 98.9% and 21.9% respectively. 3+ The adsorption effect is good.

[0061] Application Example 4

[0062] Weigh 10 mg each of CeCl3, Eu(NO3)3, Nd(NO3)3, La(NO3)3, Pr(NO3)3, Sm(NO3)3, Gd(NO3)3, Tb(NO3)3, Dy(NO3)3, Ho(NO3)3, Er(NO3)3 and Yb(NO3)3, and dissolve them in 20 mL of ultrapure water to obtain a mixed solution in which the concentration of each rare earth metal salt is 0.5 mg / mL (repeat the above process to prepare two mixed solutions of equal concentration and volume, and use inductively coupled plasma to detect the content of each rare earth metal ion in the mixed solution); weigh 20 mg of MOF808-PBTCA prepared in Example 1 and 20 mg of raw material MOF 808 (as a control), respectively disperse them in the above two mixed solutions, stir at room temperature for 20 min, and centrifuge to obtain a supernatant and a residue. The supernatant of the group with MOF 808-PBTCA and the supernatant of the group with MOF 808 were taken, and the content of each rare earth metal ion in the supernatant was detected by inductively coupled plasma. The adsorption efficiency of MOF 808-PBTCA and MOF 808 on different rare earth metal ions in the mixed solution was calculated based on the content of each rare earth metal ion in the supernatant after adsorption and the content of each rare earth metal ion in the mixed solution before adsorption. The results are shown in Table 1.

[0063] Table 1

[0064]

[0065]

[0066] As can be seen from Table 1, the adsorption efficiency of MOF 808 for rare earth metal ions at low concentrations (the concentration of rare earth metal salts is 0.5 mg / mL) is maintained at about 20%, while the adsorption efficiency of MOF 808-PBTCA prepared in Example 1 for rare earth metal ions at low concentrations (the concentration of rare earth metal salts is 0.5 mg / mL) can reach more than 97%. The adsorption efficiency of MOF 808 for rare earth metal ions is greatly improved after PBTCA is grafted, which shows that the phosphate group of PBTCA plays a very important role in the adsorption of rare earth metal ions.

[0067] Comparative Example 1

[0068] A method for preparing a porous metal organic framework derivative material, comprising the following steps:

[0069] (1) Weigh 50 mg of MOF 808 and add it into 50 mL of ultrapure water. Ultrasonic treatment is performed for 5 min to make MOF 808 disperse evenly to obtain a MOF 808 dispersion.

[0070] (2) 1.2 mg of PBTCA was added to the dispersion of MOF 808 obtained in step (1), and the mixture was stirred continuously at room temperature for 20 h. The powder was collected by centrifugation, and the collected powder was immersed in ultrapure water and washed three times within 24 h, and then washed three times with acetone within 24 h, and dried to obtain a PBTCA-grafted porous metal-organic framework derivative material (MOF 808-PBTCA). MOF808-PBTCA was a white powder with a yield of 98% and a purity of 97%.

[0071] Comparative Example 2

[0072] A method for preparing a porous metal organic framework derivative material, comprising the following steps:

[0073] (1) Weigh 50 mg of MOF 808 and add it into 50 mL of ultrapure water. Ultrasonic treatment is performed for 5 min to make MOF 808 disperse evenly to obtain a MOF 808 dispersion.

[0074] (2) Add 2 mg of PBTCA to the dispersion of MOF 808 obtained in step (1), continue stirring at room temperature for 20 hours, collect the powder by centrifugation, soak the collected powder in ultrapure water for 24 hours and wash it three times, then wash it with acetone for 3 times within 24 hours, and dry it to obtain a PBTCA-grafted porous metal-organic framework derivative material (MOF 808-PBTCA), MOF 808-PBTCA is a white powder, the yield is 97.5%, and the purity is 94%.

[0075] Comparative Example 3

[0076] The same as Example 1, except that MOF 808 is replaced by ZIF 8 of equal mass to obtain PBTCA-grafted ZIF8.

[0077] The above ZIF 8 was prepared by sequentially adding 0.3 g zinc acetate and 1.12 g 2-methylimidazole into 20 mL ultrapure water and stirring at room temperature for 24 h.

[0078] Comparative Example 4

[0079] The same as Example 1, except that PBTCA is replaced with an equal mass of 2-hydroxyphosphonoacetic acid (HPAA) to obtain 2-hydroxyphosphonoacetic acid grafted MOF 808-HPAA.

[0080] Comparative application example 1

[0081] Weigh 10 mg of CeCl3, Eu(NO3)3, and Nd(NO3)3, respectively, and dissolve them in 10 mL of ultrapure water to obtain CeCl3 solution, Eu(NO3)3 solution, and Nd(NO3)3 solution with a concentration of 1 mg / mL; disperse 20 mg of MOF 808-PBTCA prepared in Comparative Example 1 into the above CeCl3 solution, Eu(NO3)3 solution, and Nd(NO3)3 solution, respectively, stir at room temperature for 20 min, and centrifuge to obtain supernatant and residue. Take three groups of supernatants and use inductively coupled plasma to detect Ce in the supernatant. 3+ 、Eu 3+ or Nd 3+ According to the Ce content in the supernatant after adsorption 3+ 、Eu 3+ or Nd 3+ The content of Ce in the solution before adsorption 3+ 、Eu 3+ or Nd 3+ The content of MOF 808-PBTCA and the amount of MOF 808-PBTCA were calculated to obtain the effect of MOF 808-PBTCA prepared in Comparative Example 1 on Ce 3+ 、Eu 3+ and Nd 3+ The adsorption amounts were 475.9 mg / g, 435.3 mg / g and 421.8 mg / g respectively; the adsorption efficiencies were 95.18%, 87.06% and 84.36% respectively.

[0082] Comparative Application Example 2

[0083] The same as comparative application example 1, the only difference is that the MOF 808-PBTCA prepared in comparative example 1 is replaced by the MOF 808-PBTCA prepared in comparative example 2. The calculated MOF 808-PBTCA prepared in comparative example 2 has an influence on Ce 3+ 、Eu 3+ and Nd 3+ The adsorption amounts were 493.7 mg / g, 487.5 mg / g and 426.3 mg / g respectively; the adsorption efficiencies were 98.74%, 97.5% and 85.26% respectively.

[0084] Comparative Application Example 3

[0085] The same as comparative application example 1, the only difference is that the MOF 808-PBTCA prepared in comparative example 1 is replaced by the MOF 808-HPAA prepared in comparative example 4. The MOF 808-HPAA prepared in comparative example 4 is calculated to have an activity against Ce 3+ 、Eu 3+ and Nd 3+The adsorption amounts were 242.7 mg / g, 153.6 mg / g and 171.8 mg / g respectively; the adsorption efficiencies were 48.54%, 30.72% and 34.36% respectively.

[0086] Effect Example 1

[0087] Figure 1 TEM and EDS element distribution diagram of raw material MOF 808; Figure 2 TEM and EDS element distribution diagram of MOF 808-PBTCA prepared in Example 1; Figure 3 TEM and EDS element distribution diagram of MOF 808-PBTCA@Ce obtained in Application Example 1; Figure 4 TEM and EDS element distribution diagram of MOF 808-PBTCA@Eu obtained in Application Example 2; Figure 5 TEM and EDS element distribution diagram of MOF808-PBTCA@Nd obtained in Application Example 3.

[0088] from Figure 1 It can be seen that MOF 808 has a regular octahedral configuration, and the elements such as Zr, O, and C are evenly distributed; Figure 2 It can be seen that after being grafted with small molecule PBTCA, MOF 808 still maintains its original octahedral configuration, and the P element in PBTCA and the Zr, O, C and other elements contained in MOF 808 are evenly distributed, indicating that PBTCA is successfully grafted onto MOF808; Figure 3 It can be seen that after MOF 808-PBTCA adsorbs the rare earth element Ce, it still maintains the original octahedral configuration of MOF 808, and the adsorbed rare earth element Ce is evenly distributed on the surface of MOF 808-PBTCA; Figure 4 It can be seen that after MOF 808-PBTCA adsorbs the rare earth element Eu, it still maintains the original octahedral configuration of MOF 808, and the adsorbed rare earth element Eu is evenly distributed on the surface of MOF 808-PBTCA; Figure 5 It can be seen that after adsorbing the rare earth element Nd, MOF 808-PBTCA still maintains the original octahedral configuration of MOF 808, and the adsorbed rare earth element Nd is evenly distributed on the surface of MOF 808-PBTCA.

[0089] The MOF 808-PBTCA prepared in Example 1 was digested and the contents of Zr and P were measured by inductively coupled plasma, wherein the Zr content derived from MOF 808 was 13.7 mg / g, the P content derived from PBTCA was 2.16 mg / g, and the molar ratio of Zr to P in MOF 808-PBTCA was 2:1.

[0090] Effect Example 2

[0091] Figure 6 XRD (X-ray powder diffraction) patterns of the raw material MOF 808, MOF 808-PBTCA prepared in Example 1, and MOF 808-PBTCA@Ce, MOF 808-PBTCA@Eu, and MOF 808-PBTCA@Nd after adsorbing rare earth metal ions in Application Examples 1-3; Figure 7 FT-IR (Fourier transform infrared spectroscopy) graphs of the raw material MOF 808, MOF 808-PBTCA prepared in Example 1, and MOF 808-PBTCA@Ce, MOF 808-PBTCA@Eu, and MOF 808-PBTCA@Nd after adsorbing rare earth metal ions in Application Examples 1-3; Figure 8 H NMR spectra of raw material MOF 808 (a) and MOF 808-PBTCA (b) prepared in Example 1; Fig. 9 FT-IR images of ZIF 8 prepared in Comparative Example 2 and ZIF 8 grafted with PBTCA.

[0092] from Figure 6 It can be seen that after the small molecule PBTCA is grafted onto MOF 808, its XRD is consistent with MOF 808, indicating that PBTCA grafted onto MOF 808 will not destroy the structure of MOF 808; and MOF 808-PBTCA will not destroy its structure after adsorbing rare earth elements Ce, Eu, and Nd; Figure 7 It can be seen that after the small molecule PBTCA was grafted onto MOF 808, the -1 and 1230cm -1 The bending and stretching vibrations of the phosphorus-oxygen double bond (-P=O) in the phosphorus group appeared at 1700 cm -1 The stretching vibration peak of the saturated carbonyl group (C=O) appeared at the position of the saturated carbonyl group. The above results prove that PBTCA was successfully grafted into MOF-808; Figure 8 It can be seen that the peak of hydrogen in formic acid at 8.02ppm in MOF 808 completely disappears in MOF 808-PBTCA, and different hydrogen signal peaks corresponding to -CH- in PBTCA appear at 2.1ppm and 3.0ppm in MOF 808-PBTCA, which indicates that the formic acid ligands on the Zr6 cluster are almost completely replaced by PBTCA molecules; Fig. 9 It can be seen that there is no obvious change in the FT-IR graph of ZIF 8 and ZIF 8 after grafting PBTCA, and no characteristic peaks of the functional groups in PBTCA appear, indicating that PBTCA was not successfully grafted onto ZIF 8.

[0093] Effect Example 3

[0094] The Brunauer Emmett Teller (BET) method was used to test the specific surface area and pore size of the raw material MOF 808, MOF808-PBTCA prepared in Example 1, and MOF 808-PBTCA@Ce, MOF 808-PBTCA@Eu, and MOF 808-PBTCA@Nd after adsorbing rare earth metal ions in Application Examples 1-3. The results are as follows: Fig.10 As shown, a is the N2 adsorption-desorption isotherm and b is the pore size distribution diagram.

[0095] from Fig.10 It can be seen that the specific surface area and pore size of MOF 808, MOF 808-PBTCA and MOF 808-PBTCA after adsorption of rare earth elements are gradually decreasing. The following is the main distribution of specific surface area and pore size: specific surface area: MOF 808: 1183.94m 2 / g, MOF 808-PBTCA:781.64m 2 / g; MOF 808-PBTCA@Ce:612.48m 2 / g;MOF808-PBTCA@Eu:673.60m 2 / g;808-PBTCA@Nd:684.81m 2 / g. Average pore size: MOF 808: about 1.8nm, MOF 808-PBTCA: about 1.3nm; MOF 808-PBTCA@Ce, MOF 808-PBTCA@Eu, 808-PBTCA@Nd are all distributed around 1.0nm. This shows that the porous structure of MOF 808 makes it a good carrier for the adsorption of rare earth metal ions.

[0096] From the results of Effect Example 2 and Effect Example 3, it can be seen that only after PBTCA is grafted onto MOF808 with a large specific surface area and porosity can it have a better adsorption effect on rare earth metal ions.

[0097] Effect Example 4

[0098] The effect of adsorption time on adsorption efficiency was detected by inductively coupled plasma. The specific operation was as follows: 10 mg of CeCl3, Eu(NO3)3, and Nd(NO3)3 were weighed and dissolved in 10 mL of ultrapure water to obtain CeCl3 solution, Eu(NO3)3 solution, and Nd(NO3)3 solution with a concentration of 1 mg / mL; 20 mg of MOF 808-PBTCA prepared in Example 1 was dispersed in the above CeCl3 solution, Eu(NO3)3 solution, and Nd(NO3)3 solution, respectively, stirred at room temperature, and the supernatant was filtered and removed at fixed intervals. The Ce in the supernatant was detected by inductively coupled plasma. 3+ 、Eu 3+ or Nd 3+ The corresponding adsorption efficiency was calculated based on the content of Fig.11 As shown, when MOF 808-PBTCA adsorbs Ce, Eu, and Nd, it can reach adsorption equilibrium in about 15 minutes.

[0099] The adsorption efficiency of MOF 808-PBTCA prepared in Example 1 in the mixed system of transition metal ions and rare earth ions was detected by inductively coupled plasma to investigate the anti-interference ability of MOF 808-PBTCA. The specific operation was as follows: transition metal ion salts (Co(NO3)2, Ni(NO3)2, Mn(NO3)2, Zn(NO3)2, Mg(NO3)2, Na2MoO4, Cu(NO3)2, Ca(NO3)2, Hg(NO3)2) and rare earth ion salts (CeCl3, Eu(NO3)3, Nd(NO3)3, La(NO3)3, Pr(NO3)3, 2 mg each of Sm(NO3)3, Gd(NO3)3, Tb(NO3)3, Dy(NO3)3, Ho(NO3)3, Er(NO3)3) was dissolved in 20 mL of ultrapure water to obtain a mixed solution in which the concentration of each transition metal salt and rare earth metal salt was 0.1 mg / mL; 20 mg of MOF808-PBTCA prepared in Example 1 was weighed and dispersed into the above mixed solution, stirred at room temperature for 20 minutes, and centrifuged to obtain a supernatant and a filter residue. The content of each transition metal ion and rare earth metal ion in the supernatant was detected by inductively coupled plasma. The adsorption efficiency of MOF 808-PBTCA for different metal ions in the mixed solution was calculated based on the content of each transition metal ion and rare earth metal ion in the supernatant after adsorption and the content of each transition metal ion and rare earth metal ion in the mixed solution before adsorption. The results are shown in Figure 2. Fig.12 As shown, the adsorption efficiency of MOF 808-PBTCA for rare earth ions far exceeds that for transition metal ions, and the adsorption efficiency for rare earth ions remains above 98%, indicating that MOF 808-PBTCA has strong anti-interference ability.

[0100] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A porous metal organic framework derivative material for adsorbing rare earth metal ions, characterized in that: The invention comprises a porous metal organic framework and small organic molecules grafted on the porous metal organic framework.

2. The porous metal organic framework derivative material for adsorbing rare earth metal ions according to claim 1, characterized in that: The porous metal organic framework is MOF 808.

3. The porous metal organic framework derivative material for adsorbing rare earth metal ions according to claim 1, characterized in that: The organic small molecule is 2-phosphonobutane-1,2,4-tricarboxylic acid.

4. The method for preparing a porous metal organic framework derivative material for adsorbing rare earth metal ions according to any one of claims 1 to 3, characterized in that: The following steps are involved: The organic small molecule is added dropwise to the dispersion of the porous metal organic framework, and stirred continuously at room temperature to obtain the porous metal organic framework derivative material for adsorbing rare earth metal ions.

5. The preparation method according to claim 4, characterized in that: The mass ratio of the organic small molecule to the porous metal organic framework is 3:

100.

6. The preparation method according to claim 4, characterized in that: The continuous stirring time is 20 hours.

7. Use of the porous metal organic framework derivative material for adsorbing rare earth metal ions as claimed in any one of claims 1 to 3 in the adsorption of rare earth metal ions.

8. The use according to claim 7, characterized in that The rare earth metal ions are lanthanide rare earth metal ions.

Images