Adsorption chromatographic material for technetium in radioactive waste liquid and its preparation method

Abstract

This invention relates to an adsorption chromatographic material for technetium in radioactive waste and its preparation method, comprising the following steps: S1, purging air from the pores of a silica matrix; S2, mixing acetophenone, diethyl phthalate, vinylpyridine, and divinylbenzene evenly, then adding initiator azobisisobutyronitrile and initiator V-40 and mixing evenly to obtain a mixture; S3, mixing the mixture with the silica matrix under vacuum conditions, then restoring to atmospheric pressure, and then cycling under vacuum-atmospheric pressure conditions multiple times, finally restoring to atmospheric pressure; S4, subjecting the reaction system after restoring to atmospheric pressure to multiple continuous heatings, finally restoring to room temperature, and rinsing multiple times to obtain the adsorption chromatographic material. Compared with the prior art, this invention directly obtains a pyridine-type weakly basic anion exchange resin through copolymerization, eliminating the chloromethylation and amination processes in the traditional process, greatly simplifying the resin synthesis process, and improving the adsorption chromatographic material for technetium in radioactive waste. 99 Tc has a good adsorption effect.

Description

Technical Field

[0001] This invention relates to the field of radionuclide separation research in radioactive waste liquid, and in particular to an adsorption chromatographic material for technetium in radioactive waste liquid and its preparation method. Background Technology

[0002] Fission products in radioactive waste 99 Tc is a long-lived radioactive nuclide, mainly derived from... 235 U fission, which accounts for 6.03% of all uranium fission products, has a half-life of 2.13 × 10⁻⁶. 5 Radioactive nuclides decay over time, releasing low-energy beta rays. These nuclides readily migrate and diffuse in the environment. Separating and transmutating them can reduce their environmental harm, making it a target of advanced spent fuel reprocessing. Because... 99 Tc is usually found in high-level radioactive waste as TcO4. - Tc exists in anionic form. When Tc is separated and adsorbed using ion exchange, the active groups on the separation material affect TcO4. - The affinity of the ion is greater than that of the anion in the resin, thus separating Tc from the solution.

[0003] Currently, almost all commonly used ion exchange resins on the market are spherical cross-linked copolymers. The synthesis of ion exchange resins can be divided into addition polymerization and condensation polymerization methods. Addition polymerization ion exchange resins are currently the most widely used, primarily cross-linked polystyrene and cross-linked polyacrylic acid resins. The vast majority of ion exchange resins are synthesized by first synthesizing cross-linked copolymer spheres through suspension copolymerization, and then introducing the required ion exchange groups through a specific chemical reaction; the preparation process is complex. Only a few ion exchange resins are obtained by direct copolymerization of monomers with functional groups. Summary of the Invention

[0004] The purpose of this invention is to develop an ion exchange resin with a simple preparation process and high adsorption efficiency, and to provide an adsorption chromatography material for technetium in radioactive waste liquid and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a method for preparing adsorption chromatographic materials for technetium in radioactive waste liquid, comprising the following steps:

[0007] S1. Expel all air from the pores of the silica matrix;

[0008] S2. Mix acetophenone, diethyl phthalate, vinylpyridine, and divinylbenzene evenly, then add initiator azobisisobutyronitrile and initiator V-40 and mix evenly to obtain a mixture.

[0009] S3. Mix the mixture obtained in step S2 with the silica matrix obtained in step S1 under vacuum conditions, then restore atmospheric pressure, and then cycle under vacuum-atmospheric pressure conditions multiple times, and finally restore atmospheric pressure.

[0010] S4. The reaction system after restoring to normal pressure in step S3 is heated continuously multiple times until it is finally restored to room temperature. After rinsing multiple times, the adsorption chromatographic material is obtained.

[0011] In some specific embodiments, in step S2, the vinylpyridine is 4-vinylpyridine.

[0012] In some specific embodiments, in step S2, the volume ratio of acetophenone, diethyl phthalate, vinylpyridine, divinylbenzene, initiator azobisisobutyronitrile (AIBN), and initiator V-40 is 22:15:9:2:1.6:1.

[0013] In some specific embodiments, in step S3, the ratio of the mixture to the silica matrix is ​​(50-55) mL: 50 g.

[0014] In some specific embodiments, in step S3, the mixture is mixed with the silica matrix so that the mixture fully penetrates the voids of the silica matrix until no silica particles clump together.

[0015] In some specific implementations, in step S3, the system is cyclically run at least three times under vacuum-atmospheric pressure conditions to ensure an oxygen-free environment.

[0016] In some specific embodiments, three consecutive heating processes are performed in step S4.

[0017] In some specific embodiments, in step S4, the temperature of the first heating is 70°C and the heating time is 1 hour; the temperature of the second heating is 80°C and the heating time is 1 hour; the temperature of the third heating is 90°C and the heating time is 10 hours.

[0018] In some specific embodiments, in step S4, the heating rate is 10°C / min.

[0019] The second technical solution of the present invention is to provide an adsorption chromatographic material for technetium in radioactive waste liquid, based on the preparation method described in one of the above technical solutions.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) This invention uses vinylpyridine as a monomer and divinylbenzene as a crosslinking agent to directly obtain a pyridine-type weakly basic anion exchange resin through copolymerization, eliminating the chloromethylation and amination processes in the traditional process, thus greatly simplifying the resin synthesis process. Furthermore, using porous material SiO2 as a carrier, a novel N3 macroporous silica-based composite adsorbent with faster kinetic performance and stronger radiation resistance is synthesized through a vacuum impregnation-dry thermal recombination method. Extraction chromatography is then used to separate radioactive waste liquids... 99 Tc adsorption separation showed good adsorption effect, especially under the conditions of technetium concentration of 5 mmol / L and nitric acid concentration of 1 M. 99 The saturated adsorption capacity of Tc is 35.82 mg / g, and the desorption rate can reach over 90%.

[0022] (2) The adsorbent prepared by the present invention can be used multiple times. Even after 10 adsorption-desorption cycles, its saturated adsorption capacity can still reach 89% of the initial adsorption saturation capacity. Detailed Implementation

[0023] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0024] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0025] Example 1:

[0026] A method for preparing an adsorption chromatographic material for technetium in radioactive waste liquid includes the following steps:

[0027] (1) Weigh 50g of silica matrix and transfer it to a rotary evaporator. Set the rotary evaporator to a slow speed so that the silica matrix is ​​continuously stirred in the evaporation flask. Evacuate to a certain pressure environment and remove as much air as possible from the pores of the matrix.

[0028] (2) In a separate container, add 22 mL of acetophenone, then add 15 mL of diethyl phthalate. Stir with a glass rod until the mixture is homogeneous. Add 9 mL of monomer 4-vinylpyridine and 2 mL of crosslinking agent divinylbenzene, and continue stirring with a glass rod until homogeneous. Then add 1.6 mL of initiator AIBN and 1.0 mL of initiator V-40 to the mixture and stir with a glass rod until the initiators are completely dissolved.

[0029] (3) Maintain the vacuum level inside the rotary evaporator and draw the mixture from step 2 into the rotary evaporator through back suction from the feed inlet. Increase the rotation speed so that the mixture can fully contact the silica matrix and gradually enter the pores of the matrix due to capillary action until there is no obvious phenomenon of silica particles sticking together. It can be considered that the mixture has completely entered and filled the pores of the matrix.

[0030] (4) Slowly fill the rotary evaporator with nitrogen until the pressure returns to normal, then evacuate it to a certain pressure environment, and then fill it with nitrogen again. Repeat this process 2 to 3 times to ensure that the inside of the reaction vessel is an oxygen-free environment.

[0031] (5) Finally, nitrogen gas was introduced to restore the pressure inside the reaction vessel to atmospheric pressure, and the rotary evaporator was adjusted to a lower speed. The reaction vessel was heated in a constant temperature water bath, and the temperature was raised to 70°C and held for 1 hour. Then, the heating rate was controlled at 10°C / min, and the temperature was raised to 80°C and held for 1 hour. Then, the temperature was raised to 90°C at a heating rate of 10°C / min and held for 10 hours.

[0032] (6) Turn off the heating device and wait for it to return to room temperature. Transfer the resin to the sand core funnel and rinse it repeatedly with pure water until there is no obvious turbidity or oily organic matter in the filtrate and the resin is washed clean to obtain N3 adsorbent.

[0033] The prepared N3 adsorbent was tested as follows:

[0034] (1) Performance test results are shown in Table 1:

[0035] Table 1 Performance of N3 Adsorbent

[0036] Serial Number characteristic <![CDATA[N3 / SiO2]]> 1 Carrier Structure <![CDATA[SiO2]]> 2 Properties Porous particles 3 Average particle size (μm) 114.9 4 Average pore size (nm) 34.8 5 <![CDATA[Density (g / cm 3 )]]> 1.506 6 <![CDATA[Specific surface area (m 2 / g)]]> 63.27 7 Maximum operating temperature (°C) 140 8 Moisture content (wt%) 5 9 Content of supported inorganic exchanger (wt%) - 10 Content of loaded organic reagent (wt%) 70％

[0037] (2) Adsorption test:

[0038] Adsorption sample: radioactive waste liquid with technetium concentration of 5 mmol / L and nitric acid concentration of 1 M.

[0039] Adsorption process: 6g of N3 adsorbent was weighed and added to 30mL of radioactive waste liquid with a technetium concentration of 5mmol / L and a nitric acid concentration of 1M. The mixture was shaken on a shaker for 60min and then sampled for analysis. The shaking frequency of the shaker was 120rpm.

[0040] Adsorption results: N3 adsorbent adsorbed the above-mentioned radioactive waste liquid 99 The saturated adsorption capacity of Tc is 35.82 mg / g, and the desorption rate can reach more than 90%. After 10 adsorption-desorption cycles, the saturated adsorption capacity of the adsorbent can still reach 89% of the initial adsorption saturated capacity.

[0041] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. The application of an adsorption chromatographic material in adsorbing technetium from radioactive waste liquid, characterized in that, The preparation method of the adsorption chromatographic material includes the following steps: S1. Expel all air from the pores of the silica matrix; S2. Mix acetophenone, diethyl phthalate, vinylpyridine, and divinylbenzene evenly, then add initiator azobisisobutyronitrile and initiator V-40 and mix evenly to obtain a mixture. S3. Mix the mixture obtained in step S2 with the silica matrix obtained in step S1 under vacuum conditions, then restore atmospheric pressure, and then cycle under vacuum-atmospheric pressure conditions multiple times, and finally restore atmospheric pressure. S4. The reaction system after restoring to normal pressure in step S3 is heated continuously multiple times until it is finally restored to room temperature. After washing multiple times, the adsorption chromatographic material is obtained. In step S2, the volume ratio of acetophenone, diethyl phthalate, vinylpyridine, divinylbenzene, initiator azobisisobutyronitrile, and initiator V-40 is 22:15:9:2:1.6:

1. In step S4, three consecutive heating processes were performed: the first heating was at a temperature of 70°C for 1 hour; the second heating was at a temperature of 80°C for 1 hour; and the third heating was at a temperature of 90°C for 10 hours.

2. The application of the adsorption chromatographic material according to claim 1 in the adsorption of technetium in radioactive waste liquid, characterized in that, In step S2, the vinylpyridine is 4-vinylpyridine.

3. The application of the adsorption chromatographic material according to claim 1 in the adsorption of technetium in radioactive waste liquid, characterized in that, In step S3, the volume / mass ratio of the mixture to the silica matrix is ​​(50-55) mL: 50 g.

4. The application of the adsorption chromatographic material according to claim 1 in the adsorption of technetium in radioactive waste liquid, characterized in that, In step S3, the mixture is mixed with the silica matrix until the mixture fully penetrates the voids in the silica matrix until no silica particles clump together.

5. The application of the adsorption chromatographic material according to claim 1 in the adsorption of technetium in radioactive waste liquid, characterized in that, In step S3, the cycle is performed at least three times under vacuum-atmospheric pressure conditions to ensure an oxygen-free environment.

6. The application of the adsorption chromatographic material according to claim 1 in the adsorption of technetium in radioactive waste liquid, characterized in that, The heating rate is 10℃ / min.