Adsorbing material for efficiently removing thorium in wastewater and preparation method thereof

Abstract

The invention discloses an adsorption material for efficiently removing thorium in wastewater and a preparation method of the adsorption material, and relates to the technical field of radioactive wastewater pollution control. The preparation method of the adsorbing material comprises the following steps: mixing a metal organic framework material, a phosphonic acid group-containing compound, a dehydration condensing agent and a solvent, and carrying out reflux reaction to obtain the adsorbing material for efficiently removing thorium in wastewater. The adsorption material disclosed by the invention has the advantages of large specific surface area, high adsorption capacity, strong thorium selectivity, short equilibrium time, wide application range, good reusability and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radioactive wastewater pollution control, and particularly relates to an adsorption material for efficiently removing thorium in wastewater and a preparation method thereof. BACKGROUND

[0002] Thorium (Th) is a new type of nuclear fuel in the nuclear industry, and has a broad application prospect in the field of nuclear industry. In addition, thorium is also applied in the fields of aerospace, catalyst, metallurgy, etc. Thorium may be produced in radioactive wastewater containing thorium in the processes of mining, smelting, nuclear fuel production, circulation and treatment. In addition, because thorium has a similar chemical structure to rare earth elements, thorium often occurs in association with rare earth elements, and a large amount of acid radioactive thorium wastewater is also produced in the process of rare earth mine exploitation.

[0003] The radionuclide thorium in the environment will release ionizing radiation in the process of radioactive decay due to its inherent instability of the atomic nucleus, and then cause harm to organisms. When exposed to a high-dose radiation environment for a long time, the accumulation of radionuclides in organs such as liver, spleen and bone marrow can cause cancer and other radiation-related diseases. After the radionuclide thorium enters the human body, it may be long-term retained in tissues such as kidney and bone and continuously release ionizing radiation, and long-term exposure especially increases the incidence of lung cancer. Therefore, the treatment of wastewater containing radionuclide thorium ions has attracted much attention in recent years.

[0004] At present, the separation methods of radionuclide thorium in wastewater mainly include solvent extraction, chemical precipitation, membrane separation, ion exchange and adsorption method. Among them, the adsorption method has become a method for removing and recycling thorium in wastewater due to its high removal efficiency, simple operation, environmental friendliness, and regenerability of adsorbent. The adsorbent is the core of the adsorption technology, therefore, the development of thorium adsorption material with high thorium adsorption capacity, strong selectivity and good regeneration is the key to the treatment of wastewater containing radionuclide thorium. The existing thorium adsorption materials such as metal oxide nanoparticles, zeolite molecular sieve and silicon dioxide material have their own shortcomings, such as poor stability and easy aggregation of nano adsorbents, weak selectivity of zeolite molecular sieve to thorium in wastewater, and limited adsorption capacity of silicon dioxide to thorium. Therefore, it is urgent to develop an adsorbent that can selectively and efficiently remove radioactive thorium in wastewater to reduce the pollution of thorium in radioactive wastewater and waste liquid to the environment. SUMMARY

[0005] The present application aims to provide an adsorption material for efficiently removing thorium in wastewater and a preparation method thereof, so as to solve the problems in the prior art and make up for the defects of the existing adsorbents in limited removal capacity of radionuclide thorium in wastewater.

[0006] To achieve the above-mentioned purpose, the present application provides the following solutions.

[0007] One of the technical solutions of the present application: a preparation method of an adsorption material for efficiently removing thorium in wastewater, comprising the following steps:

[0008] Mixing a metal organic framework material, a compound containing a phosphonic acid group, a dehydration condensing agent and a solvent, refluxing reaction to obtain the adsorption material for efficiently removing thorium in wastewater.

[0009] Using a water-stable metal organic framework material as a carrier, and using a heating reflux method to modify the phosphonic acid group on the metal organic framework material, the removal capacity of the metal organic framework material for thorium in wastewater is improved. Specifically, the metal organic framework material can adsorb thorium ions through the interaction between the surface functional groups and the thorium ions, and the phosphonic acid group modified on the metal organic framework material can complex with the thorium ions, so that the thorium ions are firmly adsorbed on the metal organic framework material modified by the phosphonic acid group.

[0010] Further, the compound containing a phosphonic acid group includes N-(phosphonomethyl)iminodiacetic acid (abbreviated as glyphosate) hydrate or N-bis(phosphonomethyl)glycine.

[0011] Further, the metal organic framework material includes an aluminum-based metal organic framework material or a zirconium-based metal organic framework material.

[0012] Further, the dehydration condensing agent includes dicyclohexyl carbodiimide (DCC).

[0013] The dehydration condensing agent can dehydrate and condense the carboxyl group in the compound containing a phosphonic acid group and the amino group in the metal organic framework material to form an amide bond, and then stably load the phosphonic acid group on the metal organic framework material.

[0014] Further, the solvent includes N,N-dimethylformamide (DMF).

[0015] Optionally, after mixing the metal organic framework material, the compound containing a phosphonic acid group, the dehydration condensing agent and the solvent, the method further comprises the step of ultrasonic dispersion.

[0016] Optionally, the ultrasonic dispersion time is 10-100 min, preferably 30 min.

[0017] Further, the reflux reaction temperature is 100-220℃, preferably 160℃; the time is 20-60h, preferably 48h.

[0018] Optionally, the reflux reaction is carried out under stirring, and the stirring speed is 200-1000rpm, preferably 600rpm.

[0019] Further, the mass ratio of the metal organic framework material, the compound containing phosphonic acid group and the dehydrating condensing agent is 1:0.4-1:0.5-1.

[0020] Optionally, after the reflux reaction, the method further comprises the steps of cooling, centrifugal separation, washing and vacuum drying.

[0021] Optionally, the centrifugal separation is performed at a speed of 6000-12000 rpm, preferably 10000 rpm.

[0022] Optionally, the washing agent used in the washing step comprises methanol, ethanol or DMF, preferably methanol.

[0023] Optionally, the vacuum drying is performed at a temperature of 60-100℃, preferably 80℃.

[0024] Further, the aluminum-based metal organic framework material is obtained by reacting an aluminum source and 2-amino terephthalic acid.

[0025] Further, the zirconium-based metal organic framework material is obtained by reacting a zirconium source and 2-amino terephthalic acid.

[0026] Optionally, the preparation of the aluminum-based metal organic framework material comprises mixing an aluminum source, 2-amino terephthalic acid and a solvent, and heating to obtain the aluminum-based metal organic framework material.

[0027] Optionally, the preparation of the aluminum-based metal organic framework material comprises mixing an aluminum source, 2-amino terephthalic acid and a solvent, heating to obtain the aluminum-based metal organic framework material; after the reaction, naturally cooling, transferring the mixture to a centrifuge tube, centrifugal separation, washing and vacuum drying to obtain the aluminum-based metal organic framework material.

[0028] Optionally, the aluminum source comprises aluminum chloride hexahydrate.

[0029] Optionally, the solvent comprises methanol.

[0030] Optionally, the preparation of the aluminum-based metal organic framework material comprises the following preparation conditions:

[0031] The molar ratio of the aluminum source and 2-amino terephthalic acid is 1-5:0.5-3, preferably 3:1;

[0032] The heating is performed at a temperature of 100-150℃, preferably 125℃, for 2-10 h, preferably 5 h;

[0033] The centrifugal separation is performed at a speed of 8000-12000 rpm, preferably 10000 rpm, for 2-10 min, preferably 5 min;

[0034] The cleaning agent used in the cleaning process includes methanol, ethanol or DMF, preferably methanol;

[0035] The temperature of the vacuum drying process is 60-100℃, preferably 80℃, and the time is 6-18h, preferably 12h.

[0036] Optionally, the preparation process of the zirconium-based metal organic framework material includes mixing a zirconium source, 2-amino terephthalic acid, a solvent and acetic acid, and heating the mixture to obtain the zirconium-based metal organic framework material.

[0037] The more specific preparation process of the zirconium-based metal organic framework material includes mixing a zirconium source, 2-amino terephthalic acid and a solvent, then adding acetic acid, and heating the mixture to obtain the zirconium-based metal organic framework material.

[0038] Optionally, the zirconium source includes zirconium chloride.

[0039] Optionally, the solvent includes DMF.

[0040] Optionally, the preparation process of the zirconium-based metal organic framework material includes the following preparation conditions:

[0041] The molar ratio of the zirconium source to 2-amino terephthalic acid is 0.5-3:0.5-3, preferably 1:1;

[0042] The volume ratio of the acetic acid to the solvent is 1-5:10-40;

[0043] The temperature of the heating process is 100-150℃, preferably 120℃, and the time is 10-36h, preferably 24h.

[0044] The rotation speed of the centrifugal separation process is 8000-12000rpm, preferably 10000rpm, and the time is 2-10min, preferably 5min.

[0045] The cleaning agent used in the cleaning process includes methanol, ethanol or DMF, preferably methanol and / or DMF;

[0046] The temperature of the vacuum drying process is 60-100℃, preferably 80℃, and the time is 6-18h, preferably 12h.

[0047] Further, the metal organic framework material is preferably an aluminum-based metal organic framework material (referred to as CAU), and the compound containing a phosphonic acid group is preferably N-(phosphonomethyl) iminodiacetic acid.

[0048] CAU exhibits three unique advantages: first, the [AlO6] octahedral units form secondary building units (SBUs) through μ2-OH bridges, which endow the material with excellent chemical stability (acid corrosion resistance); second, the amino-modified phthalic acid ligand provides a rich surface active site (the surface has a rich NH2 group); third, the three-dimensional pore system (pore size distribution 1.0-4.0 nm) is suitable for the introduction of macromolecular ligands.

[0049] Glyphosate (PMIDA) is a phosphonic group-containing organic substance, and two carboxyl groups and one phosphonic group are contained in one glyphosate molecule. The P=O bond (bond length about ) of the phosphonic group has stronger electron-donating ability than the carboxyl C=O (bond length about ), and forms a more stable five-membered ring chelate with Th 4+ (the ionic radius is about ). At the same time, the PMIDA molecule size (0.82 nm) matches the CAU pore size, which can avoid pore blockage in the adsorption process. More importantly, its bifunctional structure allows precise modification through a mild reflux reaction (100-220 DEG C) to graft onto the CAU material.

[0050] The second technical scheme of the present application is an adsorption material for efficiently removing thorium in wastewater, which is prepared by the above preparation method.

[0051] The third technical scheme of the present application is the application of the above adsorption material for efficiently removing thorium in wastewater in the adsorption and removal of thorium in acid thorium-containing wastewater.

[0052] Further, the pH value of the acid thorium-containing wastewater is 2-5, preferably 3.5.

[0053] Further, the thorium concentration in the acid thorium-containing wastewater is ≤350 mg / L, and the adsorption removal effect is better within this range.

[0054] Further, the dosage of the adsorption material for efficiently removing thorium in wastewater is 30-300 mg / L, preferably 100 mg / L.

[0055] The present application discloses the following technical effects:

[0056] The application prepares an adsorption material for removing thorium in wastewater efficiently, uses a water stable metal organic framework material as a carrier, and adopts a heating reflux method to modify phosphonic acid groups on the metal organic framework material, thereby improving the removal capacity of the metal organic framework material for thorium in wastewater. The application studies the removal effect of the phosphonic acid group modified metal organic framework material on thorium in simulated wastewater, and the prepared thorium adsorption material performs well, and the maximum adsorption capacity of the adsorption material for Th(IV) is 199.50 mg / g when pH is 3.5. The prepared radionuclide thorium adsorption material has the advantages of large specific surface area, high adsorption capacity, strong selectivity for thorium, short equilibrium time, wide application range, and good reusability. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0058] Figure 1 SEM and EDS diagrams of the phosphonic acid group modified zirconium metal organic framework material prepared for example 2 and example 3, wherein A is the SEM diagram of example 2, B is the SEM diagram of example 3, and C-D are the EDS diagrams of example 3.

[0059] Figure 2 XRD diagrams of the phosphonic acid group modified zirconium metal organic framework material prepared for example 2 and example 3 and the zirconium metal organic framework material.

[0060] Figure 3 Test results of the influence of contact time and temperature on the adsorption of thorium in water by the phosphonic acid group modified aluminum metal organic framework material.

[0061] Figure 4 Test results of the selective adsorption performance of the phosphonic acid group modified aluminum metal organic framework material for Th(IV) in a variety of rare earth metal ion coexisting solutions.

[0062] Figure 5 X-ray photoelectron spectrograms of the phosphonic acid group modified aluminum metal organic framework material before and after adsorbing Th(IV), wherein a is the XPS spectrum of CAU-PMIDA before and after adsorption, and b is the XPS decomposition spectrum of P 2p in CAU-PMIDA before and after adsorption.

[0063] Figure 6 Influence of solution pH on the adsorption of thorium by the phosphonic acid group modified aluminum metal organic framework material.

[0064] Figure 7 Reusability test results for phosphonate group modified aluminosilicate metal-organic framework materials. DETAILED DESCRIPTION

[0065] The following detailed description of various example embodiments of the application is not to be considered limiting of the scope or spirit of the application, but rather as a description of certain aspects, features and embodiments of the application.

[0066] It should be understood that the terms used herein are for the purpose of describing particular embodiments and are not intended to limit the application. Additionally, for numerical ranges that are expressed in a range format, it is intended that any numerical value implicitly recited within the range is also expressly stated. For example, a range of 1.0 to 10.0 is also explicitly disclosed as a range of 2.0 to 8.0, 3.0 to 7.0, 4.0 to 6.0, 5.0 to 5.0, and 5.5 to 5.5, etc. Each smaller range that falls within a broader range is also explicitly disclosed. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.

[0067] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All patents, patent applications, publications, and descriptions mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the patents, patent applications, publications, and descriptions are cited.

[0068] Many modifications and variations of this application can be made in the light of the above teachings without departing from the spirit and scope thereof. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The examples and embodiments described herein are exemplary only and are not intended to be limiting.

[0069] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional elements or steps.

[0070] It should be noted that any parts of the present application not specifically described are conventional means in the art and are not the focus of the present application.

[0071] In the following examples, comparative examples and test examples of the present application, room temperature refers to 20-30°C, unless otherwise specified.

[0072] In the following examples, comparative examples and test examples of the present application, each raw material used is commercially available, unless otherwise specified.

[0073] Example 1

[0074] An adsorption material for efficiently removing thorium in wastewater, the preparation steps of which are as follows:

[0075] 1) 2.95 g of aluminum chloride hexahydrate and 0.75 g of 2-amino terephthalic acid were added to 30 mL of methanol, stirred for 30 min to obtain a mixed solution. The mixed solution was transferred to a reaction kettle, and the reaction kettle was placed in an oven, and reacted at 125 DEG C for 5 h. After cooling, the mixture was transferred to a centrifuge tube, centrifuged at 10,000 rpm for 5 min, cleaned with methanol, and vacuum dried at 80 DEG C for 12 h to obtain an aluminum-based metal organic framework material (denoted as CAU);

[0076] 2) 100 mg of the aluminum-based metal organic framework material prepared in step 1), 48.14 mg of N-(phosphonomethyl)iminodiacetic acid hydrate, and 51.35 mg of dicyclohexyl carbodiimide were added to a round-bottom flask containing 80 mL of DMF, and ultrasonically dispersed for 30 min;

[0077] 3) The round-bottom flask in step 2) was placed in an oil bath pot, heated to reflux at 160 DEG C, and stirred at 600 rpm for 48 h. After the reaction was completed, it was naturally cooled to room temperature;

[0078] The cooled mixture in step 3) was transferred to a centrifuge tube, centrifuged at 10,000 rpm for 3 min, cleaned with methanol, and vacuum dried at 80 DEG C for 12 h to obtain a phosphonic acid group modified aluminum-based metal organic framework material (denoted as CAU-PMIDA), which is an adsorption material for efficiently removing thorium in wastewater.

[0079] Example 2

[0080] An adsorption material for efficiently removing thorium in wastewater, the preparation steps of which are as follows:

[0081] 1) 466 mg of zirconium chloride and 362.3 mg of 2-amino terephthalic acid were added to 60 mL of DMF, and 7.2 mL of acetic acid was added. Stirring at 350 rpm for 30 min, after mixing, it was transferred to a reaction kettle, and the reaction kettle was placed in an oven, and hydrothermally reacted at 120 DEG C for 24 h. After natural cooling, the reaction was transferred to a centrifuge tube, centrifuged at 10,000 rpm for 5 min, and the precipitate was cleaned with DMF and methanol in turn, and vacuum dried at 80 DEG C for 12 h to obtain a zirconium-based metal organic framework material;

[0082] 2) 100 mg of the zirconium-based metal organic framework material prepared in step 1), 50 mg of N-bis(phosphonomethyl)glycine, and 50 mg of dicyclohexyl carbodiimide were added to a round-bottom flask containing 80 mL of DMF, and ultrasonically dispersed for 30 min;

[0083] 3) The round-bottom flask in step 2) is placed in an oil bath, heated to reflux at 160°C, and stirred at 600 rpm for 24 h. After the reaction is completed, it is naturally cooled to room temperature;

[0084] 4) The cooled mixture in step 3) is transferred to a centrifuge tube, centrifuged at 10000 rpm for 3 min, washed with methanol, and vacuum dried at 80°C for 12 h to obtain a phosphonic acid group modified zirconium metal organic framework material (denoted as UiO-GP-1), which is an adsorption material for efficiently removing thorium in wastewater.

[0085] Example 3

[0086] An adsorption material for efficiently removing thorium in wastewater, the preparation steps are as follows:

[0087] 1) 466 mg of zirconium chloride and 362.3 mg of 2-amino terephthalic acid are added to 60 mL of DMF, and 7.2 mL of acetic acid is added. Stir at 350 rpm for 30 min, and then transfer the mixture to a reaction kettle. The reaction kettle is placed in an oven, and hydrothermal reaction is carried out at 120°C for 24 h. After natural cooling, the reaction product is transferred to a centrifuge tube, centrifuged at 10000 rpm for 5 min, and the precipitate is washed with DMF and methanol in sequence. Vacuum drying is carried out at 80°C for 12 h to obtain a zirconium metal organic framework;

[0088] 2) 100 mg of the zirconium metal organic framework material prepared in step 1), 100 mg of N-bis(phosphonomethyl)glycine, and 100 mg of dicyclohexyl carbodiimide are added to a round-bottom flask containing 80 mL of DMF, and ultrasonic dispersion is carried out for 30 min;

[0089] 3) The round-bottom flask in step 2) is placed in an oil bath, heated to reflux at 160°C, and stirred at 600 rpm for 24 h. After the reaction is completed, it is naturally cooled to room temperature;

[0090] 4) The cooled mixture in step 3) is transferred to a centrifuge tube, centrifuged at 9000 rpm for 3 min, washed with methanol, and vacuum dried at 80°C for 12 h to obtain a phosphonic acid group modified zirconium metal organic framework material (denoted as UiO-GP-2), which is an adsorption material for efficiently removing thorium in wastewater.

[0091] Test Example 1

[0092] To characterize the properties of the phosphonic acid group modified metal organic framework material, SEM, EDS, and XRD characterization of the phosphonic acid group modified metal organic framework material are carried out in this test example, and the results are shown in Figure 1 and Figure 2 .

[0093] Figure 1SEM and EDS images of the phosphonic group modified zirconium metal organic framework material prepared in Example 2 and Example 3, wherein A is the SEM image of Example 2, B is the SEM image of Example 3, C-D are the EDS images of Example 3.

[0094] Figure 2 XRD images of the phosphonic group modified zirconium metal organic framework material prepared in Example 2 and Example 3 and the zirconium metal organic framework material.

[0095] The SEM results show that the synthesized zirconium metal organic framework material is a regular octahedron structure, the surface is smooth, the particle size distribution is uniform, and the particle size is about 100 nm. After modification by the phosphonic group, the microstructure of the material is not destroyed, indicating that the material has good structural stability.

[0096] The EDS (element mapping energy spectrum analysis image) results show that the signal of phosphorus element is uniformly distributed on the surface of the material, indicating that the phosphonic group is successfully modified on the surface of the material. The signal of zirconium element is uniformly distributed on the surface of the material, indicating that the modification of the phosphonic group does not destroy the microstructure of the material.

[0097] The XRD results show that the diffraction peaks of the zirconium metal organic framework material at 2θ = 7.3°, 8.5°, 25.8° correspond to (111), (002), (224) crystal faces respectively, indicating that the zirconium metal organic framework material is successfully synthesized. After modification by the phosphonic group, the peak position of the material does not change significantly, but compared with the material before modification, the peak intensity is reduced. These XRD results show that although the modification of the phosphonic group will lead to a decrease in the crystallinity of the zirconium metal organic framework, the crystal structure is basically maintained intact, the physical phase of the zirconium metal organic framework is still the main component of the adsorption material, proving that the crystal structure of the material has significant stability.

[0098] Test Example 2

[0099] In order to characterize the properties of the phosphonic group modified aluminum metal organic framework material, the BET characterization of the phosphonic group modified aluminum metal organic framework material (CAU-PMIDA finally prepared in Example 1) and the aluminum metal organic framework material (CAU prepared in Example 1 step 1) was carried out, and the results are shown in Table 1.

[0100] Table 1

[0101]

[0102] The BET results show that the pore sizes of the aluminum-based metal organic framework material and the aluminum-based metal organic framework material modified by phosphonic acid groups are 2.554 nm and 2.995 nm respectively, indicating that both the materials are mesoporous materials with a pore size in the range of 2-50 nm. After modification by phosphonic acid groups, the specific surface area of the aluminum-based metal organic framework material is reduced from 1187.2 m 2 / g to 648.1 m 2 / g, and the pore volume is reduced from 0.223 cm 3 / g to 0.210 cm 3 / g, indicating that the specific surface area and the pore volume of the aluminum-based metal organic framework are slightly reduced after modification by phosphonic acid groups, but still remain at a relatively large level, and the pore size is increased from 2.554 nm to 2.995 nm, which may be due to the formation of larger mesopores on the surface of the aluminum-based metal organic framework by phosphonic acid groups.

[0103] Application Example 1

[0104] This application example studies the performance of the metal organic framework material modified by phosphonic acid groups in adsorbing and removing thorium in water.

[0105] The adsorption experiment process is as follows: 100 mL of Th(IV) solution is added to a 250 mL conical flask, the initial concentration of Th(IV) is 20-250 mg / L, the solution pH is 3.5, then 0.05 g of adsorbent (the metal organic framework material modified by phosphonic acid groups prepared in Example 1-3, the unmodified zirconium-based metal organic framework material or the unmodified aluminum-based metal organic framework material) is added, the conical flask is sealed with a sealing film, placed in a constant temperature shaker, 125 r / min, 25℃, shaken for 1 h, filtered with a needle filter, the Th(IV) concentration in the solution before and after adsorption is measured by using a PQ9000 type inductively coupled plasma optical emission spectrometer (ICP-OES), and the Langmuir model is used to fit the isothermal adsorption data to obtain the maximum adsorption capacity of thorium on the adsorbent. The results are shown in Table 2.

[0106] Table 2

[0107]

[0108] As shown in Table 1, the thorium removal efficiency of the metal organic framework material modified by phosphonic acid groups prepared in the application is better than that of the unmodified zirconium-based metal organic framework material and the unmodified aluminum-based metal organic framework material, and the thorium removal effect of the aluminum-based metal organic framework material modified by phosphonic acid groups prepared in Example 1 is the best, and the adsorption capacity of Th(IV) reaches 199.50 mg / g.

[0109] Application Example 2

[0110] The application example studies the influence of contact time and temperature on the removal of thorium in solution by phosphonic acid group modified aluminum-based metal organic framework material.

[0111] The adsorption experiment process is as follows: the initial concentration of Th(IV) solution is 100 mg / L, the solution pH is 3.5, the adsorbent (phosphonic acid group modified aluminum-based metal organic framework material CAU-PMIDA prepared in the example 1) is added in an amount of 0.5 g / L, and the solution is shaken at a speed of 125 r / min for 0, 1 min, 5 min, 10 min, 20 min, 30 min, 60 min, 120 min, 180 min, 240 min and 360 min at different temperatures of 298 K, 308 K and 318 K respectively. The sample is filtered by using a needle filter, and the Th(IV) concentration in the solution before and after adsorption is measured by using a PQ9000 type inductively coupled plasma optical emission spectrometer (ICP-OES). The results are shown in the following table. Figure 3 As shown in the table, the Th(IV) adsorption amount of the phosphonic acid group modified aluminum-based metal organic framework material increases rapidly within 1 min of contact with the thorium solution, reaches adsorption equilibrium within 60 min, and the adsorption amount of Th(IV) by the adsorbent gradually increases with the increase of temperature. The saturated adsorption amounts at 298 K, 308 K and 318 K are 110.56 mg / g, 118.64 mg / g and 123.12 mg / g respectively, indicating that the adsorption process of Th(IV) is an endothermic process.

[0112] Application Example 3

[0113] The application example studies the selective adsorption of thorium ions by the phosphonic acid group modified aluminum-based metal organic framework material.

[0114] The adsorption experiment process is as follows: 100 mL of a mixed solution of Th 4+ , La 3+ , Ce 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Er 3+ , Yb 3+ is prepared with pH = 3.5, the initial concentration of each element is 100 mg / L, 50 mg of phosphonic acid group modified aluminum-based metal organic framework material (CAU-PMIDA prepared in the example 1) is added, and the solution is shaken at a speed of 125 r / min for 1 h. The concentrations of Th, La, Ce, Nd, Sm, Gd, Er and Yb remaining in the solution are tested. The selective adsorption capacity of the phosphonic acid group modified aluminum-based metal organic framework material for thorium is calculated according to formula (1).

[0115]

[0116] In the formula, STh selectivity level of the adsorbent material to thorium ions, in %; Q e(Th) adsorption amount of the adsorbent material to thorium ions, in mg / L; Q e(All) adsorption amount of the adsorbent material to all coexisting metal ions in the solution, in mg / L.

[0117] The results, as shown in Figure 4 The selective adsorption effect of the phosphonic acid group modified aluminometallo-organic framework material on Th(IV) reached 80.84%, and the adsorption amount was much higher than that of the remaining metal ions in the solution, indicating that the phosphonic acid group modified aluminometallo-organic framework material had good selectivity to Th(IV).

[0118] The phosphonic acid group modified aluminometallo-organic framework material CAU-PMIDA before and after adsorption was analyzed by X-ray photoelectron spectroscopy, and the results are shown in Figure 5 , wherein a is the XPS spectrum of CAU-PMIDA before and after adsorption, and b is the XPS decomposition spectrum of P 2p in CAU-PMIDA before and after adsorption. The analysis results show that Th(IV) in the solution is adsorbed on the phosphonic acid group modified aluminometallo-organic framework material by complexation with the phosphonic acid groups on the surface of the phosphonic acid group modified aluminometallo-organic framework.

[0119] Application Example 4

[0120] This application example studies the influence of different solution pH on the removal of thorium in the solution by the phosphonic acid group modified aluminometallo-organic framework material.

[0121] The experimental process is as follows: The thorium solution used in the experiment was prepared from thorium nitrate hydrate and deionized water, and the pH value of the thorium solution was adjusted to 2.0-3.5 using a hydrochloric acid solution with a concentration of 0.01-1 mol / L and a sodium hydroxide solution. The initial concentration of Th(IV) solution was 100 mg / L, and the adsorbent (the phosphonic acid group modified aluminometallo-organic framework material CAU-PMIDA prepared in Example 1 and the unmodified aluminometallo-organic framework material CAU) was added in an amount of 100 mg / L. The conical flask was sealed with a sealing film, placed in a constant temperature shaker, shaken at 125 r / min and 25℃ for 1 h, filtered with a needle filter, and the Th(IV) concentration in the solution before and after adsorption was measured by a PQ9000 type inductively coupled plasma optical emission spectrometer (ICP-OES). The results are shown in Figure 6 As can be seen from the figure, in the pH range of 2.0-3.5, the adsorption amount of the two materials increased with the increase of pH. This is because in a strong acidic environment, there are a large number of H + on the surface of the adsorbent material, which is positively charged and attracts Th 4+The static electric repulsion force is generated to inhibit the adsorption of thorium. The adsorption effect of the material is improved as the pH of the solution increases. The adsorption amount of thorium ions of the CAU-PMIDA modified by the phosphonic acid group is obviously increased. The adsorption amount is increased from 0 mg / g of CAU to 41.4 mg / g in an acidic environment with pH = 2.0, and the adsorption amount of Th 4+ is increased from 53.2 mg / g to 113.48 mg / g under the condition of pH = 3.5, which indicates that the phosphonic acid group has a strong adsorption effect on thorium ions under acidic conditions.

[0122] Application Example 5

[0123] This application example studies the reusability of the aluminum-based metal organic framework material modified by the phosphonic acid group.

[0124] The experimental process is as follows: the initial concentration of Th(IV) solution is 100 mg / L, the temperature is 298 K, the adsorbent (aluminum-based metal organic framework material CAU-PMIDA modified by the phosphonic acid group prepared in Example 1) is added in an amount of 100 mg / L, the pH of the solution is 3.5, the conical flask is sealed with a sealing film, and is placed in a constant temperature shaker at 125 r / min and 25℃ for 1 h. The solution is filtered with a needle filter, and the Th(IV) concentration in the solution before and after adsorption is measured by using a PQ9000 type inductively coupled plasma emission spectrometer (ICP-OES). After one adsorption experiment, 0.1 mol / L of ethylenediaminetetraacetic acid disodium solution is used as a thorium ion coupling agent to remove the thorium ions on the adsorbent. Specifically, the adsorbent saturated with adsorption is soaked in the ethylenediaminetetraacetic acid disodium solution for 60 min, and then is cleaned with pure water, dried, and subjected to a re-adsorption experiment. The experiment is repeated for four times. As shown in Figure 7 the results, the adsorption amount of the aluminum-based metal organic framework material modified by the phosphonic acid group for Th(Ⅳ) can still reach 72.02% after four repeated use experiments, which indicates that the aluminum-based metal organic framework material modified by the phosphonic acid group has good reusability.

[0125] The above-described examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for preparing an adsorbent material for efficiently removing thorium from wastewater, characterized in that, Includes the following steps: The metal-organic framework material, the phosphonic acid group-containing compound, the dehydrating condensing agent and the solvent are mixed and refluxed to obtain the adsorbent material for the efficient removal of thorium from wastewater.

2. The preparation method according to claim 1, characterized in that, The compounds containing phosphonic acid groups include N-(phosphonomethyl)iminodiacetic acid hydrate or N-bis(phosphonohydroxymethyl)glycine.

3. The preparation method according to claim 1, characterized in that, The metal-organic framework material includes aluminum-based metal-organic framework materials or zirconium-based metal-organic framework materials.

4. The preparation method according to claim 1, characterized in that, The dehydrating condensing agent includes dicyclohexylcarbodiimide; And / or, the solvent includes N,N-dimethylformamide.

5. The preparation method according to claim 1, characterized in that, The reflux reaction is carried out at a temperature of 100–220°C for a duration of 20–60 h.

6. The preparation method according to claim 1, characterized in that, The mass ratio of the metal-organic framework material, the phosphonic acid group-containing compound, and the dehydrating condensing agent is 1:0.4 to 1:0.5 to 1.

7. A preparation method as described in claim 3, characterized in that, The aluminum-based metal-organic framework material is obtained by reacting an aluminum source with 2-aminoterephthalic acid. And / or, the zirconium-based metal-organic framework material is obtained by reacting a zirconium source with 2-aminoterephthalic acid.

8. An adsorbent material for efficiently removing thorium from wastewater, prepared by the method according to any one of claims 1-7.

9. The application of the adsorbent material for efficiently removing thorium from wastewater as described in claim 8 in the adsorption and removal of thorium from acidic thorium-containing wastewater.

10. The application as described in claim 9, characterized in that, The pH value of the acidic thorium-containing wastewater is 2 to 5.

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