CN114591244A - Material for separating technetium and preparation method thereof - Google Patents

Abstract

The invention discloses an ionic liquid material, a preparation method of the ionic liquid material, a material formed by soaking the ionic liquid material in diatomite or resin, and applications of the materials. The ionic liquid material is a diamide imidazolium salt functionalized ionic liquid material MIMDIDOA shown in the formula, the structure of the ionic liquid material is shown in the formula, and the MIMDIDOA material and the material formed by soaking the ionic liquid material in diatomite or resin can be used for separating ReO from radioactive solution in acidic, neutral and alkaline environments₄ ^‑/TcO₄ ^‑And has the advantages of reaching extraction equilibrium in a short time when being used for separating technetium, diluting the technetium and containing TcO₄ ^‑The waste water is hugeThe contact area of the ion trap can fully play the role of selectively extracting and separating target ions.

Description

Material for separating technetium and preparation method thereof

Technical Field

The invention relates to a material and a preparation method thereof, in particular to a material for separating technetium from radioactive waste liquid in nuclear industry and a preparation method thereof.

Background

The nuclear power generation is an important way for reducing carbon dioxide emission and realizing carbon neutralization. With the rapid development of nuclear power, radioactive wastes are produced in large quantities, but there is always a lack of an effective, reliable and economical strategy for how to treat and dispose of these radioactive wastes; on the other hand, if these radioactive wastes are not properly managed, humans are threatened by serious nuclear safety accidents.

Of the radioactive waste produced by nuclear energy, technetium-99 (β, Emax ═ 295.5keV, t)_1/2＝2.13 ×10⁵Year) is²³⁵U、²³⁹Fission products of Pu with fission yields of up to 6%¹. In the presence of an aqueous solution of a compound of formula (I),⁹⁹tc is mainly a stable heptavalent pertechnetate anion (⁹⁹TcO₄ ^-) Are present. Such oxoanions are very soluble in water and readily migrate in the environment and enter the biosphere by absorption by plants and accumulation by animals. Due to the characteristics of long half-life period, high fission yield, good environmental mobility and the like,⁹⁹tc is considered to be one of the most dangerous radionuclides²The environmental pollution problem that it may bring will affect the long-term storage and after-treatment of the spent fuel far. To avoid the threat of contamination problems, it is imperative to develop a functional material that can separate and extract Tc, but due to the TcO₄ ^-The anions have large volume and low charge density²Equal factors, selective identification and separation of TcO from aqueous solution₄ ^-And certainly a huge challenge.

Currently, TcO is separated and extracted₄ ^-Mainly comprises the following materials: precipitating agent³Reducing agent⁴An extractant^5,6Ion exchange resin⁷Inorganic cation framework⁸Cationic metal-organic frameworks (MOFs)^9,10And Cationic Polymer Networks (CPNs)¹¹And the like. The extraction agent is widely developed in chemical application because the extraction method has many advantages, such as: unique selectivity, capability of reducing hydrolysis of products through phase transfer, fast mass transfer and short extraction process period¹²Facilitating continuous operation, etc. Currently reported methods for separation and extraction of TcO₄ ^-The commonly used extractant mainly comprises RNH₂(Primary amine), R₂NH (secondary amine), R₃N (tertiary amine) and (R)₄N)⁺Amine-based extractants such as quaternary ammonium salts^13,14Unfortunately, they have a load bearing capacityLow force, easy emulsification and generation of third phase⁵And the like, which greatly hinder their practical application. On the other hand, most are used for separation and extraction of TcO₄Materials capable of selectively separating TcO from Low-level radioactive wastewater at pH2-13₄ ^-However, there are few reports of Tc separation from nitric acid solutions. Many problems in the reprocessing of spent fuels can be avoided if Tc can be separated directly from the nitric acid solution or highly radioactive spent liquor of spent fuels. However, many materials are less selective due to their instability in acidic environments or lack of effective binding sites, which also means that Tc separation materials are designed to meet these requirements.

Since all isotopes of technetium are radioactive, in basic research, research is usually carried out using as a substitute the non-radioactive element rhenium (Re) with physicochemical properties similar to those of Tc belonging to the same group VIIB¹⁵。

Disclosure of Invention

The invention provides a diamide imidazolium salt functionalized ionic liquid material and a material formed by soaking the ionic liquid material in diatomite or resin, and also provides a preparation method of the material and a using method of the material.

The diamide imidazolium salt functionalized ionic liquid material is abbreviated as MIMDIDOA in the following, the structure of which is shown as formula 1,

the MIMDIDOA ionic liquid material is impregnated in diatomaceous earth or resin to form another material of the present invention.

The preparation method of the ionic liquid is shown as the formula 2, namely

1) Dripping chloroacetyl chloride into a solution of diisooctylamine dissolved in water and dichloromethane removed, stirring, heating to room temperature in an ice water bath, fully stirring for reaction, carrying out reduced pressure distillation to obtain dichloromethane, and carrying out column chromatography separation to obtain an intermediate product, wherein a chromatographic eluent is petroleum ether: ethyl acetate 5: 1;

2) dissolving the intermediate obtained in the previous step and imidazole in an acetonitrile solvent, carrying out full reflux reaction at 82 ℃, removing acetonitrile under reduced pressure, dissolving the product in dichloromethane, fully washing with water, separating an organic phase, removing dichloromethane, and carrying out column chromatography separation to obtain a product, wherein an eluent used for chromatography is ethyl acetate-methanol-10: 1.

The MIMDIDOA material can be used for separating ReO from radioactive solution in acidic, neutral and alkaline environments₄ ^-/TcO₄ ^-。

The specific method for separating technetium from radioactive solution by adopting the diamide imidazolium salt functionalized ionic liquid material MIMDIDOA material comprises the following steps:

1) extraction of

Mixing 1ml of MIMDIDOA solution (with the dilution concentration of 1-500mmol/L) diluted by n-dodecane and technetium-containing solution (ppb-ppm) and placing the mixture in a shaking table at 25 ℃ for full shaking extraction;

2) back extraction

The organic phase was separated from the solution from the previous step, 5ml of 6M HCl (hydrochloric acid concentration >6M) was added and mixed, and the technetium was back-extracted after sufficient shaking.

Tests of the present invention show that another material formed by immersing MIMDIDOA ionic liquid material in diatomite or resin can separate ReO from acid, neutral and alkaline environments₄ ^-/TcO₄-, and can be eluted with 6M HCl hydrochloric acid.

The invention has the following advantages:

(a) the preparation method of MIMDIDOA is relatively simple.

(b) MIMDIDOA can separate ReO in acidic, neutral and alkaline environment₄-/TcO₄ ^-。

(c) The equilibrium time is very short, and only 2 minutes is needed to reach the extraction equilibrium basically.

(d) The raw materials for MIMDIDOA synthesis are readily commercially available and are inexpensive to synthesize.

(e) MIMDIDOA is used for extraction, and diluted to be mixed with TcO₄ ^-The wastewater has huge contact area and can fully act for selectively extracting and separating target ions.

(f) MIMDIDOA is a high boiling point material with high stability, acid resistance and alkali resistance.

(g) The material after multiple use can be used for burning the organic functional groups for post-treatment without degradation.

(h) ReO can be separated from acidic, neutral and alkaline environments by immersing the ionic liquid of the invention in diatomite or resin₄ ^-/TcO₄ ^-。

When the material is used for separating technetium, the extraction balance can be reached in a short time, and even when different salts with different concentrations and technetium coexist, the material still has a high distribution ratio.

Drawings

FIG. 1 MIMDIDOA, MIMDIDOA @ ReO₄ ^-、NH₄ReO₄(data referencing)¹⁶) Infrared spectrum of

FIG. 2 nuclear magnetic resonance hydrogen spectroscopy of MIMDIDOA

FIG. 3 MIMDIDOA and MIMDIDOA @ ReO₄ ^-Electrospray ionization mass spectrometry of positive ions

FIG. 4 MIMDIDOA @ ReO₄ ^-Anion electrospray mass spectrometry

FIG. 5 contact time extraction of ReO for MIMDIDOA₄ ^-The influence of (c).

FIG. 6 pH vs. MIMDIDOA extraction of ReO₄ ^-Influence of (2)

FIG. 7 nitric acid concentration vs. MIMDIDOA adsorption of ReO₄ ^-The influence of (c) on the performance of (c).

FIG. 8 concentration of extractant vs. TcO in simulated alkaline waste liquid₄ ^-The effect of extraction.

FIG. 9 concentration of extractant vs. TcO in simulated acidic waste liquid₄ ^-The effect of extraction.

Detailed Description

The invention is illustrated below with reference to examples. Since all isotopes of technetium are radioactive, as in the basic study, part of the experiments in the present invention have been carried out using the non-radioactive element rhenium (Re) as a substitute, with physicochemical properties similar to those of Tc belonging to the same group VIIB¹⁵。

Preparation of materials

The chemical reaction formula of the preparation of the invention is shown in formula II

The preparation process comprises the following steps:

1) synthesizing an intermediate: adding 5.56g of chloroacetyl chloride dropwise into 30ml of water-removed dichloromethane solution containing 12.08g of diisooctylamine, adding 10.60g of sodium carbonate, heating to room temperature in an ice-water bath, fully stirring for 5h, distilling off dichloromethane under reduced pressure, and separating the crude product by column chromatography (eluent: petroleum ether: ethyl acetate: 5:1) to obtain 8.31g of the desired product;

2) synthesis of MIMDIDOA

4.76g of the intermediate obtained in the previous step and 0.34g of imidazole are dissolved in 20ml of acetonitrile solvent, the mixture is refluxed for 72 hours under the condition of 82 ℃, after the acetonitrile is removed under reduced pressure, the product is dissolved in dichloromethane and washed sufficiently with water, an organic phase is separated, the dichloromethane is removed by reduced pressure distillation, and the crude product is separated by column chromatography (eluent is ethyl acetate: methanol 10:1) to obtain 2.18g of the required product.

The prepared material has a structure which is prepared by FT-IR,¹H NMR, ESI-MS and other technical means, and refer to FIGS. 1 to 4.

Secondly, selectively separating TcO from low-level wastewater and high-level wastewater₄ ^-

The specific experimental process of the invention is as follows:

1. extraction of ReO by using functionalized ionic liquid MIMDIDOA₄ ^-Time of equilibrium of

Taking 1ml of 2mmol/L MIMDIDOA solution diluted by n-dodecane and 5ml of 100ppm ReO₄ ^-Mixing the solutions, placing in a shaking table at 25 deg.C, shaking sufficiently, and selecting 0.5; 1; 2; 5; 8; 10; 15; measuring ReO in water sequentially at 20min time point₄ ^-And calculating the distribution ratio.

As shown in fig. 5, the ratio reached 25.8 in 2 minutes and the distribution varied substantially less with time, so that MIMDIDOA extraction process was substantially balanced in two minutes.

2. Extraction of ReO by using functionalized ionic liquid MIMDIDOA₄ ^-Is influenced by pH

1ml of 2.2mmol/L N-dodecane diluted MIMDIDOA solution was added to 5ml of 100ppm ReO₄ ^-In the solution, the mixed solution is shaken for 1h at 25 ℃, and the water phase is taken out for determination of ReO by centrifugal separation₄ ^-And calculating the distribution ratio.

As shown in fig. 6, the distribution ratio tends to increase first and then decrease in the range of pH2-13, and MIMDIDOA has the best extraction performance at pH8, and the distribution ratio reaches 52.7.

3. Extraction of ReO by using functionalized ionic liquid MIMDIDOA₄ ^-The performance of (A) is influenced by the concentration of nitric acid

1ml of 200mmol/L MIMDIDOA solution diluted with 80% dodecane and 20% n-octanol was mixed with 5ml of 100ppm ReO₄ ^-Mixing the solutions, shaking the mixture at 25 deg.C for 1 hr, centrifuging, and measuring ReO with water phase₄ ^-And calculating the distribution ratio. As shown in FIG. 7, it can be seen that the partition ratio decreases as the concentration of nitric acid increases, and when the concentration of nitric acid increases from 1mol/L to 5mol/L, the partition ratio decreases from 19.1 to 0.36, and thus NO₃ ^-The competition of (A) is to influence MIMDIDOA to extract TcO₄ ^-/ReO₄ ^-The main factor of performance degradation.

4. Extraction of TcO from alkaline simulated waste liquid by using functional ionic liquid MIMDIDOA₄ ^-

Weighing MIMDIDOA with different mass, dissolving in n-dodecane to obtain 1-500mmol/L extractant solution, taking 1ml organic phase and 5ml extractant solution containing 0.4mM TiO₄ ^-Alkaline waste liquid of¹⁷(component (C)Mix as in table 1), shake the mixture at 25 ℃ for 1h, and centrifuge. As a result, as shown in FIG. 8, it can be seen that the extraction ratio of MIMDIDOA increases with the concentration of the extractant, and the extraction ratio reaches 99.8% when the concentration increases from 1mmol/L to 500mmol/L, the partition ratio reaches 2450%, and the extraction ratio reaches 99.2% at 250mmol/L

TABLE 1 composition of alkaline Low-level effluent

5. Extraction of TcO from acidic simulated high-level radioactive waste liquid by using functionalized ionic liquid MIMDIDOA₄ ^-

Weighing MIMDIDOA with unequal mass, dissolving in n-dodecane to obtain 50-300mmol/L solution, dissolving in 40% n-octanol and 60% n-dodecane to obtain 500mmol/L solution, mixing 1ml organic phase with 5ml TcO containing 0.16mg/L₄ ^-1M HNO of₃,3M HNO₃Acid waste liquid of (2)¹⁸The preparation method is as shown in table 2), the mixed solution is shaken for 1h at 25 ℃, and then is centrifugally separated, and the aqueous phase is taken to measure the technetium concentration and calculate the distribution ratio. As shown in FIG. 9, it can be seen that HNO is present at 1M₃And 3M HNO₃The distribution ratio under the condition is increased along with the increase of the concentration of the extracting agent, and 1M HNO₃When the concentration of MIMDIDOA is increased from 50mmol/L to 500mmol/L, the distribution ratio is increased from 4.7 to 55.3, and the first-order extraction rate is up to 92%; 3M HNO₃When the concentration of MIMDIDOA is increased to 500mmol/L from 50mmol/L, the extraction distribution ratio is increased to 22.5 from 2.5, and the highest first-order extraction rate reaches 82%.

TABLE 2 composition of acidic high-level radioactive waste

6. Method for back extraction

1ml of 4mmol/L MIMDIDOA diluted with dodecane was added to 5ml of 100ppm ReO₄ ^-After shaking the solution at 25 ℃ for 1 hour, the organic phase was separated by centrifugation, mixed with 5ml of 6M HCl and shaken for 1 hour. The results showed 82.2% ReO₄ ^-Can be back-extracted by 6M HCl, and can extract more than 95% of ReO after 3 times of repeated operations₄ ^-Back extraction.

7. The ionic liquid of the invention is soaked in diatomite or grease to separate ReO in acidic, neutral and alkaline environments₄ ^-/TcO₄ ^-Substantially the same as the ionic liquid treatment.

Claims (5)

1. A diamido imidazolium salt functionalized ionic liquid material MIMDIDOA is characterized in that the structure is shown as formula 1,

2. a material characterized in that the ionic liquid of claim 1 is directly extracted or impregnated into diatomaceous earth or resin for adsorption.

3. The method of producing the material of claim 1, wherein the material is represented by formula 2, i.e.:

1) dripping chloroacetyl chloride into a solution of diisooctylamine dissolved in water and dichloromethane removed, stirring, heating to room temperature in an ice water bath, fully stirring for reaction, carrying out reduced pressure distillation to obtain dichloromethane, and carrying out column chromatography separation to obtain an intermediate product, wherein a chromatographic eluent is petroleum ether: ethyl acetate 5: 1;

2) dissolving the intermediate obtained in the previous step and imidazole in an acetonitrile solvent, carrying out full reflux reaction at 82 ℃, removing acetonitrile under reduced pressure, dissolving the product in dichloromethane, fully washing with water, separating an organic phase, removing dichloromethane, and carrying out column chromatography separation to obtain a product, wherein an eluent used in the chromatography is ethyl acetate-methanol-10: 1.

4. The use of the material of claim 1 or 2 for separating technetium from radioactive solutions.

5. The method for separating technetium from radioactive solution using the material of claim 1, wherein said material is selected from the group consisting of

1) Extraction of

Mixing 1ml of MIMDIDOA solution (concentration 1-500mmol/L) diluted by n-dodecane and technetium-containing solution (ppb-ppm) and shaking in a shaking table at 25 deg.C for extraction;

2) back extraction

The organic phase was separated from the solution from the previous step, 5ml of 6M HCl (hydrochloric acid concentration >6M) was added and mixed, and the technetium was back-extracted after sufficient shaking.

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