CN115044059B

CN115044059B - Rapid preparation method and application of MOFs material for adsorbing and separating rhenium or technetium

Info

Publication number: CN115044059B
Application number: CN202210829918.1A
Authority: CN
Inventors: 肖成梁; 康康
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2022-07-14
Filing date: 2022-07-14
Publication date: 2023-02-14
Anticipated expiration: 2042-07-14
Also published as: CN115044059A

Abstract

The invention relates to the technical field of nuclear fuel post-processing, in particular to a rapid preparation method and application of MOFs (metal-organic frameworks) materials for adsorbing and separating rhenium or technetium, wherein the preparation method comprises the following steps: mixing tetra (4-pyridine biphenyl) ethylene and silver nitrate in an organic solvent A for reaction, and filtering, washing and drying a product to obtain the MOFs material; the organic solvent A is a mixed solvent of acetonitrile and dimethyl sulfoxide; or, the tetra (4-pyridine biphenyl) ethylene is dissolved in the organic solvent B, the silver nitrate is dissolved in the acetonitrile, the MOFs material is obtained after the two solutions are mixed, the MOFs material can be generated in 5-10min by the method, even the adsorbing material product can be obtained by directly mixing, the yield can reach 94% at most, compared with the MOFs preparation process in the prior art, the method is usually more than several days, the speed is greatly improved, a novel method is provided for preparing the pertechnetate adsorbent in a large scale, and the material can efficiently remove the radioactive pollutant TcO ₄ ^‑ And ReO ₄ ^‑ The effect is excellent.

Description

Rapid preparation method and application of MOFs material for adsorbing and separating rhenium or technetium

Technical Field

The invention relates to the technical field of nuclear fuel post-processing, in particular to a rapid preparation method and application of MOFs materials for adsorbing and separating rhenium or technetium.

Background

The nuclear energy is taken as clean and efficient green energy, is gradually one of the most promising clean energy, provides powerful energy guarantee for the rapid development of the economy of the country, and makes great contribution to reducing the carbon emission. Meanwhile, a large amount of radioactive waste is generated along with the development of nuclear energy, and safe disposal of the generated nuclear waste and elimination of nuclides released into the environment in nuclear accidents have been key problems in the safe development of nuclear energy. Of the long-lived elements produced in nuclear fission, the fission product Tc-99 is typically a long-lived fission product (t) _1/2 ＝2.13×10 ⁵ Year), mainly with highly water-soluble and highly stable pertechnetate (TcO) ₄ ^- ) In the form of a typical anionic radionuclide. Separation of TcO from Nuclear waste and Nuclear contaminated Water systems ₄ ^- Has important significance for promoting the post-treatment of the spent fuel, restoring the ecological environment and protecting the human health.

Among the separation methods developed at present, the solid phase adsorption technology has the advantages of simple operation, no secondary pollution, high adsorption capacity, good selectivity and the like, and is more suitable for solvent extraction, precipitation, reduction, membrane separation and other methodsThere is a wide range of concerns. In many applications for TcO ₄ ^- Among the materials for adsorptive separation, metal Organic Framework (MOF) has the characteristics of large specific surface area, high porosity, flexible structure and easy modification, and is widely favored by researchers, such as SCU-103 cationic MOF material (Shen N, yang Z, liu S, et al.99TcO) reported by the project of Wang Shuao of Suzhou university ₄ ^- removal from legacy defense nuclear waste by an alkaline-stable 2D cationic metal organic framework[J]Nature communications,2020,11 (1): 1-12.) are capable of adsorptive removal of radioactive pertechnetate from strongly alkaline waste liquors. The preparation of the MOF material is mainly obtained by a solvothermal method or a hydrothermal method through long-time reaction at high temperature and high pressure, reports of rapid synthesis at room temperature are concentrated in the field of neutral MOF materials constructed by carboxyl and imidazole organic ligands, and a method for direct mixed synthesis at room temperature is not reported in the field of cationic MOF materials.

The method can be used for TcO in the reported research ₄ ^- Most of the cation MOF materials for adsorption separation lack good acid-base stability, and especially under the condition that a large number of competitive ions exist, the adsorption capacity is greatly influenced, and the TcO cannot be subjected to adsorption separation ₄ ^- High efficiency selective separation. Meanwhile, the preparation of the cation MOFs material needs to be carried out in a reaction kettle, the synthesis process has the characteristics of high temperature, high pressure, long reaction time and the like, for example, in the early research result CN 112322282A of the applicant, although the reaction conditions are relatively mild, the reaction preparation time of the MOFs material is as long as 48-128h, and the process is long. Until now, no method and related research reports for rapidly preparing cationic MOF materials at room temperature exist, so that the industrial production and application of the materials are greatly limited.

In summary, in order to realize the large-scale preparation of cationic MOF as pertechnetate adsorbent, those skilled in the art urgently need to develop a MOF material capable of being rapidly prepared at room temperature, and meanwhile, the material also has a series of advantages of excellent acid-base stability, rapid adsorption kinetics, ultrahigh selectivity, recyclability, and the like.

Disclosure of Invention

Hair brushAiming at the problems of long preparation process, long time consumption, difficult preparation and the like of a cation MOF adsorption material used for pertechnetate adsorption in the prior art, the invention provides an MOFs material (ReO) for adsorbing and separating rhenium or technetium ₄ ^- As TcO ₄ ^- Substitute), the method can produce MOFs material within 5-10min, even directly mix to obtain the adsorbing material product, the yield can reach 94% at most, compared with the MOFs preparation process in the prior art, the method usually reaches more than several days, the speed is greatly improved, a new method is provided for large-scale preparation of pertechnetate adsorbent, and the material can efficiently remove radioactive pollutant TcO ₄ ^- And ReO ₄ ^- The effect is excellent.

In order to realize the purpose, the invention adopts the technical scheme that:

a rapid preparation method of MOFs material for adsorbing and separating rhenium or technetium comprises the following steps: mixing tetra (4-pyridine biphenyl) ethylene and silver nitrate in an organic solvent A for reaction, and filtering, washing and drying a product to obtain the MOFs material; the organic solvent A is a mixed solvent of acetonitrile and dimethyl sulfoxide. The ligand adopted in the invention is a rigid planar ligand, the pyridine functional group has paired lone electron pairs and can form a coordination bond with transition metal ions, and the nitrogen atom belongs to a soft atom ligand and coordinates with transition metal silver based on the theoretical guidance of soft-hard combination to form a quadruple interpenetration stable structure, so that ligand tetra (4-pyridine biphenyl) ethylene and silver nitrate can rapidly and stably generate MOFs materials in a solvent.

The molar ratio of the tetra (4-pyridine biphenyl) ethylene to the silver nitrate is 1.8-1.2, and in the MOFs structure, the ligand tetra (4-pyridine biphenyl) ethylene and the silver nitrate are molded according to the relation of 1:1, so that the reaction raw materials of the four (4-pyridine biphenyl) ethylene and the silver nitrate are prepared according to 1:1.

In the mixing reaction process, any mode of heating, room temperature stirring or ultrasound is adopted to accelerate the reaction speed.

Wherein the heating temperature is 60-120 ℃, the reaction time is more than 10min, and the volume ratio of acetonitrile to dimethyl sulfoxide (DMSO) in the organic solvent A is 20. By adopting the method, a hydrothermal kettle can be adopted in the heating process, so that the solvent proportion is prevented from changing due to transitional volatilization of the solvent at high temperature, and a common glass container can be selected for synthesis preparation during low-temperature synthesis; after the reaction is carried out for 10min, the product MOFs is produced. The heating temperature is preferably 70-90 ℃, and the energy consumption can be reduced at the temperature, so that a reaction kettle is not used, and the preparation process of the reaction is simplified. Further preferably 80 ℃. The reaction temperature and the solvent proportion in the method can produce the product, and have no obvious influence on the preparation result of the material, but the product cannot be effectively synthesized or the yield is obviously reduced when the reaction temperature and the solvent proportion are beyond the range.

If the content of DMSO is further increased, the ligand is difficult to dissolve, the yield of the produced MOFs material is reduced, and if the content of DMSO is further increased, the MOFs material cannot be produced.

Preferably, the volume ratio of acetonitrile to DMSO in organic solvent a is 5:2. The MOFs material generated under the proportion has the fastest speed and higher yield.

Further preferably, the reaction time under the heating condition is 10min-24h; more preferably, the reaction time is 10min-3h, the reaction yield is not increased much when the reaction time is more than 3h, and the reaction yield is not increased any more when the reaction time is more than 24 h.

Wherein the reaction time is more than 10min under room temperature stirring; the volume ratio of acetonitrile to dimethyl sulfoxide in the organic solvent A is 20. Preferably, the reaction time is 10min-3h at room temperature with stirring. After stirring for 10min, the product is produced, and when stirring is continued for 3h, the reaction is complete. Heating can also be carried out in the stirring process, so that the reaction process can be accelerated, the reaction yield is improved, and the energy consumption in the MOF preparation is increased.

Wherein, the reaction is carried out for more than 5min under the action of ultrasonic waves, and the volume ratio of acetonitrile to dimethyl sulfoxide in the organic solvent A is 20. Preferably, the reaction time under the ultrasonic condition is 5min-1h. When the ultrasonic treatment is carried out for 5min, the product is produced, when the ultrasonic treatment is carried out for 1h, the reaction is complete, and the reaction time is prolonged without obvious improvement on the yield.

In the above-mentioned method of heating, stirring at room temperature or ultrasonication, the tetrakis (4-pyridylbiphenyl) ethylene ligand does not need to be completely dissolved in the mixed solution, but only needs to have a certain solubility.

The invention also provides another method for rapidly preparing the MOFs material for adsorbing and separating rhenium or technetium, which comprises the following steps: dissolving tetra (4-pyridine biphenyl) ethylene in an organic solvent B, dissolving silver nitrate in acetonitrile, mixing the two solutions, filtering, washing and drying the product to obtain the MOFs material;

the organic solvent B is a mixed solvent of dichloromethane and acetonitrile with the volume ratio of 20; the volume ratio of the organic solvent B to the acetonitrile for dissolving the silver nitrate is 20.5-1.

According to the method, two solutions can be simply stirred after being mixed to be uniformly mixed, the reaction time in the mixing process almost does not need to wait, the precipitation output of the MOFs product can be seen directly after mixing, the preparation process can be completed within 1min at most, the MOFs material can be obtained after filtering, washing and drying, the test yield is up to 94%, and the effect is excellent. And the preparation basically does not need the consumption of external energy, and is very suitable for industrial large-scale production.

The processes of filtering, washing and drying the product obtained in the rapid preparation method refer to that the MOFs material is produced in a precipitation mode in a solution, and the final MOFs material is obtained by filtering, cleaning and centrifuging the product by adopting solutions such as methanol, acetonitrile or ethanol and the like, and drying the product to remove redundant solvents.

In the method of heating reaction, because the temperature reduction process still increases the yield of the MOF material, the temperature reduction mode can select to turn off heating and natural cooling, and then the post-treatment process is performed.

The invention also provides application of the MOFs material prepared by the preparation method in adsorption separation of rhenium or technetium.

The application of the MOFs material in the adsorption separation of rhenium or technetium comprises the following steps: the MOFs material is placed in a solution containing rhenium or technetium for treatment for 40min-24h, and the effect of removing the rhenium or technetium in the solution is realized;

the solid-to-liquid ratio of the MOFs material to the rhenium or technetium-containing solution is 1-10; the removal rate of rhenium is 35% or more and the removal rate of technetium is 80% or more, and excellent removal rates of technetium and rhenium can be obtained at a low solid-to-liquid ratio.

Preferably, the solid-liquid ratio is 2-10, the removal rate of rhenium is more than 55%, and the removal rate of technetium is more than 95%; more preferably, the solid-to-liquid ratio is 5 to 10, the removal rate of rhenium is 75% or more, and the removal rate of technetium is 99% or more.

Compared with the prior art, the invention has the following beneficial effects:

(1) In a mixed solvent of acetonitrile and DMSO, ligand tetra (4-pyridine biphenyl) ethylene and silver nitrate can be rapidly prepared into the MOFs material in a short time, wherein the ultrasonic process only needs 5min to generate a product, the reaction can be completed after 1h, compared with MOF synthesis in other researches, the MOF synthesis needs dozens of hours of high-temperature heating requirements, the synthesis method is greatly simplified, and the MOFs material can be expected to be used for industrial MOF production and preparation.

(2) The invention also finds that the ligand tetra (4-pyridine biphenyl) ethylene is firstly dissolved in the mixed solution of dichloromethane and acetonitrile and is directly mixed with the acetonitrile solution dissolved with silver nitrate, so that the product can be immediately obtained, the preparation of MOFs can be completed within 1min at most, the consumption of external energy is basically not needed, and the method is very suitable for industrial large-scale production.

(3) The MOFs material prepared by the invention is used for adsorbing rhenium or technetium, the effect is obvious, and the highest adsorption rate can reach 99%.

Drawings

FIG. 1 is an X-ray powder diffraction pattern of a synthesized cationic MOF material under different conditions.

FIG. 2 is an SEM image of a heated synthetic cationic MOF material from example 1.

FIG. 3 is an SEM image of room temperature stirred synthetic cationic MOF material of example 2.

FIG. 4 is an SEM image of the ultrasonically synthesized cationic MOF material of example 3.

FIG. 5 is an SEM image of the direct mixing method for synthesizing cationic MOF material in example 4.

FIG. 6 shows the adsorption of TcO by a cationic MOF material in application example 1 ₄ ^- Percentage graph.

FIG. 7 shows adsorption of ReO by a cationic MOF material in application example 2 ₄ ^- Percentage diagram。

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Those skilled in the art should understand that they can make modifications and equivalents without departing from the spirit and scope of the present invention, and all such modifications and equivalents are intended to be included within the scope of the present invention.

Reagents used in the following embodiments, such as silver nitrate, tetrakis (4-pyridylbiphenyl) ethylene, methanol, ethanol, dimethylsulfoxide, N-dimethylformamide, acetonitrile, sodium hydroxide, and sodium nitrate, can be purchased from sahn chemical company and used without further purification.

Example 1

40mg of tetra (4-pyridylbiphenyl) ethylene and 10.6mg of silver nitrate were weighed into a reaction tube, and 14mL of CH was measured ₃ Adding a mixed solvent (v/v, 10/4) of CN and DMSO, sealing, putting into an oven, heating to 80 ℃ for 3h, closing the oven after heating, and naturally cooling. And filtering the reaction solution, washing products obtained by filtering with methanol and deionized water respectively, and then drying to obtain light yellow powder, namely the cationic MOF material, wherein the yield is 80%.

An X-ray powder of the MOF material after 3h of reaction at 80 ℃ is given in fig. 1, with no organic ligand raw material peaks, indicating complete substrate reaction. FIG. 2 is an SEM topography of the product produced by the heating process, which shows that the MOF material obtained by the process is octahedral particles.

Example 2

Weighing 40mg of tetra (4-pyridylbiphenyl) ethylene and 10.6mg of silver nitrate into a reaction tube, and measuring 14mL of CH ₃ CN and DMSO mixed solvent (v/v, 10/4) is added, and then stirred for 10min, at this time, the product is produced in the reaction, but a large amount of raw materials are not completely reacted, and the diffraction peak of the raw materials existing in the short reaction time can be seen from the PXRD diagram in figure 1. After stirring for 3 hours, the reaction solution was filtered, and the filtrate was filteredAnd washing the obtained product with methanol and deionized water respectively, and then drying to obtain light yellow powder, namely the cationic MOF material, wherein the product does not have PXRD diffraction peaks of the raw materials, and the yield is 92% by test calculation.

PXRD diffraction peaks of the product after stirring for 10min, 30min and 3 hours are given in fig. 1, wherein there are still significant substrate peaks and product peaks after stirring for 10min and 30min, indicating that there is production of product in a shorter reaction time, but the substrate is not reacted completely, the yield is lower, but there is no substrate peak when the reaction is extended to 3 hours, indicating that the substrate reaction is complete and the obtained product is all MOF material.

The microscopic morphology SEM of the prepared MOFs material is shown in figure 3, and the MOFs material obtained by the room-temperature stirring method is also octahedral particles, which shows that the morphology of the MOFs material is consistent with that of the MOFs material prepared by the method 1.

Example 3

40mg of tetra (4-pyridylbiphenyl) ethylene and 10.6mg of silver nitrate were weighed into a reaction tube, and 14mL of CH was measured ₃ CN and DMSO mixed solvent (v/v, 10/4) is added, then ultrasonic treatment is carried out for 5min at room temperature, the product is produced in the reaction, but a large amount of raw materials are not completely reacted, and the diffraction peak of the raw materials existing in the short reaction time can be seen from the PXRD diagram in the attached figure 1. And (3) filtering the reaction solution after continuously performing ultrasonic treatment for 1 hour, washing the filtered product with methanol and deionized water respectively, and then drying to obtain light yellow powder, namely the cation MOF material, wherein the yield is 95%.

PXRD diffraction peaks of products subjected to ultrasonic treatment for 5 minutes, 30 minutes and 1 hour are shown in figure 1, the products are produced when the products are reacted for 5 minutes and 30 minutes respectively, raw material peaks still exist, and no bottom material peak exists after the reaction is prolonged to 1 hour, so that the reaction is complete and no raw material is left. It can be seen from fig. 4 that the MOF material prepared by the ultrasonic method has an octahedron shape, which is consistent with the material shape obtained by heating and stirring at room temperature.

Example 4

40mg of tetrakis (4-pyridylbiphenyl) ethylene was weighed out and dissolved in 20mL of a mixed solution of dichloromethane and acetonitrile (v/v, 10/4), and silver nitrate in an equimolar amount was dissolved in 1mL of CH ₃ CN solution, and is added dropwiseStirring the organic ligand, uniformly mixing for 1min, stopping stirring, filtering the reaction solution, washing the filtered product with methanol and deionized water respectively, and drying to obtain light yellow powder, namely the cationic MOF material, wherein the yield is 94%.

The PXRD diffraction peaks of the product prepared by direct mixing are shown in fig. 1, wherein there are no diffraction peaks of the organic ligand raw material, and it can be seen that the method can effectively and rapidly prepare the cationic MOFs material, and the reaction speed is significantly faster than other methods, while maintaining a very high yield. As shown in figure 5, the obtained MOFs material has the same shape as the materials shown in figures 2-4, and is octahedral particles, which indicates that the material prepared by direct mixing is the same as the products prepared by other methods.

Application example 1

Preparing a simulated waste liquid according to the concentration of each component in the reported low-radioactivity waste liquid in a certain area. The waste liquid contains TcO ₄ ^- 2.49,5.03, 12.58 and 19.99mgMOFs samples are respectively weighed and placed in 2.5mL of simulated waste liquid, the samples are sampled after being stirred for 24 hours, the samples are filtered by a 0.22 mu m water system filter membrane, the concentration of the residual technetium is measured by a liquid scintillation counter, and the TcO in the samples is detected ₄ ^- The concentration changes to obtain the MOF material to TcO in the simulated waste liquid ₄ ^- Adsorption removal capacity property of (1). The results are shown in FIG. 6, where the solid-to-liquid ratios were 1/1, 2/1, 5/1 and 8/1, the cationic MOF material was paired with TcO ₄ ^- The adsorption removal rate of (A) was divided into 83%, 96%, 99% and 99%. Indicating that the cationic MOF material is responsible for TcO in the effluent ₄ ^- Has very strong adsorption removal capacity, and the MOF is currently used for removing TcO in the waste liquid under the condition of low solid-to-liquid ratio ₄ ^- The material with the highest removal capacity. The removal rate of the conventional adsorption material is usually over 90% at a solid-to-liquid ratio of 10/1, only a few materials increase the solid-to-liquid ratio to 5/1, and the removal rate reaches 97%, while the removal rate of the MOFs of the invention can reach 96% at 2/1 and 99% at 5/1.

Application example 2

According to the reported concentrations of each component in a river, as ReO ₄ ^- Replacement of TcO ₄ ^- And (5) preparing simulated waste liquid. Weighing 5, 10, 15, 20, 25 and 50mg samples respectively, placing in 5mL simulated waste liquid, stirring for 12h, sampling, filtering with 0.22 μm water-based filter membrane, measuring the concentration of rhenium in the sample by ICP-MS, and detecting ReO therein ₄ ^- The change of the concentration of the MOF material to the ReO in the river waste liquid ₄ ^- Adsorption removal capacity properties. As shown in FIG. 7, the ionic MOF material pairs ReO at solid-to-liquid ratios of 1/1, 2/1, 3/1,4/1,5/1 and 10/1 ₄ ^- The adsorption removal rates of (A) were divided into 37%,59%,68%,72%,76% and 90%. Indicating that the cationic MOF material pair mimics ReO in the river ₄ ^- Has very strong adsorption removal capacity, and the MOF is currently used for simulating ReO in the river ₄ ^- The material with the highest removal capacity. As above, only a very small increase in the solid-to-liquid ratio of the material to 40/1 can achieve a removal rate of 90%.

Claims

1. A rapid preparation method of MOFs materials for adsorbing and separating rhenium or technetium is characterized by comprising the following steps: tetra (4-pyridine biphenyl) ethylene and silver nitrate are mixed and reacted in an organic solvent A, and a product is filtered, washed and dried to obtain the MOFs material; the organic solvent A is a mixed solvent of acetonitrile and dimethyl sulfoxide.

2. The rapid preparation method of MOFs material for the adsorptive separation of rhenium or technetium according to claim 1, wherein the molar ratio of tetra (4-pyridylbiphenyl) ethylene to silver nitrate is 1.

3. The method for rapidly preparing MOFs material for absorbing and separating rhenium or technetium according to claim 1, wherein the reaction speed is accelerated by any one of heating, stirring at room temperature and ultrasound during the mixing reaction.

4. The rapid preparation method of MOFs materials for the adsorptive separation of rhenium or technetium according to claim 3, wherein the heating temperature is 60-120 ℃, the reaction time is more than 10min, and the volume ratio of acetonitrile to dimethylsulfoxide in the organic solvent A is 20.

5. The method for rapid preparation of MOFs material for adsorptive separation of rhenium or technetium according to claim 3, wherein the reaction time is 10min or more under stirring at room temperature; the volume ratio of acetonitrile to dimethyl sulfoxide in the organic solvent A is 20.

6. The process for the rapid preparation of MOFs materials for the adsorptive separation of rhenium or technetium according to claim 3, wherein the reaction is carried out for more than 5min under the action of ultrasound, and the volume ratio of acetonitrile to dimethylsulfoxide in the organic solvent A is 20.

7. The method for the rapid preparation of MOFs material for the adsorptive separation of rhenium or technetium according to claim 3, wherein the reaction time under heating is 10min to 3h; and/or the reaction time is 10min-3h under room temperature stirring; and/or the reaction time is 5min-1h under the ultrasonic condition.

8. A rapid preparation method of MOFs material for adsorbing and separating rhenium or technetium is characterized by comprising the following steps: dissolving tetra (4-pyridine biphenyl) ethylene in an organic solvent B, dissolving silver nitrate in acetonitrile, mixing the two solutions, filtering, washing and drying the product to obtain the MOFs material;

9. Use of the MOFs material obtainable by the process according to any one of claims 1 to 8 for the adsorptive separation of rhenium or technetium.

10. Use of MOFs materials according to claim 9 for the adsorptive separation of rhenium or technetium comprising the steps of: the MOFs material is placed in a solution containing rhenium or technetium for treatment for 40min-24h, and the effect of removing the rhenium or technetium in the solution is realized;

the solid-to-liquid ratio of the MOFs material to the rhenium or technetium-containing solution is 1-10; the removal rate of rhenium is 35% or more, and the removal rate of technetium is 80% or more.