Targeting complexing agent, preparation method thereof and method for treating radioactive waste liquid

Abstract

The invention provides a targeted complexing agent, a preparation method thereof and a method for treating radioactive waste liquid. The molecular structural formula of the targeted complexing agent is as follows: # imgabs0 #, wherein R1, R2, R3 and R4 are one or more of a phosphate group, a hydroxyl group or an amino group. According to the invention, the light-operated complexing agent is utilized to realize selective complexing of radionuclide ions; the form size of radionuclide ions is specifically increased through the light-operated complexing agent, so that the radionuclide ions are effectively combined with a membrane separation technology with a relatively large aperture, and the rejection rate of non-radioactive inorganic salt ions is remarkably reduced while efficient rejection of radionuclide complexes is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of radioactive waste liquid treatment, and particularly relates to a targeted complexing agent, a preparation method thereof, and a method for treating radioactive waste liquid. Background Art

[0002] Radioactive waste liquid contains radioactive nuclide ions such as uranium-238 (U), cesium-137 (Cs + ), strontium-90 (Sr 2+ ), cobalt-60 (Co 2+ ), etc., as well as non-radioactive pollutants. The non-radioactive pollutants mainly include organic pollutants such as surfactants, and inorganic salt ions such as calcium (Ca 2+ ), magnesium (Mg 2+ ) existing in seawater. The research and development of radioactive waste liquid treatment technology is particularly crucial, as it directly determines the generation amount of radioactive solid waste and waste gas, as well as the complexity of subsequent treatment. Currently, traditional treatment technologies such as evaporation concentration, ion exchange, and chemical precipitation are mainly used for radioactive waste liquid treatment. However, these traditional treatment technologies have low interception selectivity for radioactive pollutants and non-radioactive solutes, resulting in a large amount of secondary solid waste generation and bringing new solid waste disposal problems. Therefore, there is an urgent need to develop a new method for treating radioactive waste liquid to meet the requirements of efficient pollution control and volume reduction of radioactive waste liquid. Summary of the Invention

[0003] Based on the above technical problems, the present invention provides a targeted complexing agent. The targeted complexing agent is a light-controlled complexing agent with reversible structural interconversion, which can directionally increase the morphological size of nuclide ions, and then combine with a membrane separation technology with a larger pore size to achieve high interception of radioactive nuclide complexes, while reducing the interception rate of non-radioactive inorganic salt ions.

[0004] The present invention also provides a method for treating radioactive waste liquid, which can selectively complex and separate radioactive nuclide ions, and can reduce the energy consumption and operation cost of the membrane separation process. The method of the present invention significantly reduces the generation of radioactive nuclide-containing solid waste, reduces environmental risks and disposal costs. It is applicable to multiple fields such as nuclear waste treatment, radioactive wastewater treatment, and environmental remediation, providing a new technical means for efficient pollution control and volume reduction of radioactive waste liquid.

[0005] The technical solution of the present invention is as follows:

[0006] A targeted complexing agent, the molecular structural formula of the targeted complexing agent is as follows:

[0007] ;

[0008] Wherein, R1, R2, R3, and R4 are one or more of a phosphate group, a hydroxyl group, or an amino group.

[0009] In the above structural formula, R1, R2, R3, and R4 are independent of each other, and R1, R2, R3, and R4 may be the same or different.

[0010] The targeting complexing agent of the present invention is a photoswitchable complexing agent with a reversible interconversion structure. Among them, the targeting complexing agent contains functional groups specifically coordinated with radionuclides, and these functional groups enable the photoswitchable complexing agent to specifically complex radionuclides; the functional groups coordinated with radionuclides are phosphate groups, hydroxyl groups, or amino groups. The targeting complexing agent of the present invention uses azobenzene as a photoswitch and phosphate groups, hydroxyl groups, or amino groups as coordination functional groups. The targeting complexing agent of the present invention can achieve its recycling by controlling the light source, thereby improving the economy and sustainability of the entire separation process.

[0011] The structural formula of the phosphate group is as follows:

[0012] .

[0013] Preferably, the targeting complexing agent is specifically:

[0014] ;

[0015] or

[0016] ;

[0017] The preparation method of the above-mentioned targeting complexing agent includes the following steps: coupling an azomethyl nucleophilic reagent and an amide compound with a leaving group in a solvent to obtain the targeting complexing agent. When using an amide compound containing both phosphate groups, hydroxyl groups, and amino groups or a mixture of two or more compounds to react with an azomethyl nucleophilic reagent, R1, R2, R3, and R4 in the final product may be different. Among them, the molar ratio of the amide compound with a leaving group to the azomethyl nucleophilic reagent can be any ratio, but preferably the molar ratio of the amide compound with a leaving group to the azomethyl nucleophilic reagent is not less than 2:1.

[0018] Among them, the azomethyl nucleophilic reagent is azomethyl halide, and the azomethyl halide is obtained by reacting azotoluene with methyl halide (CH3X, X is a halogen, Cl, Br, or I). Among them, the molar ratio of methyl halide to azotoluene can be any, but preferably the molar ratio of methyl halide to azotoluene is not less than 2:1. The reaction formula is as follows:

[0019] .

[0020] Among them, the leaving group is haloacetyl.

[0021] Among them, the preparation method of the amide compound with a leaving group is as follows: React an electrophilic reagent with an amide compound in the presence of a catalyst to obtain an amide compound with a leaving group. Among them, the electrophilic reagent can be NBS (N-bromosuccinimide), 2-bromoacetyl bromide, and the catalyst can be DCC (N,N'-dicyclohexylcarbodiimide), a metal catalyst, AIBN, BPO (benzoyl peroxide), etc. The solvent can be carbon tetrachloride or DCE (dichloroethane). During the preparation, the molar ratio of the electrophilic reagent to the amide compound can be arbitrary, but preferably the molar ratio of the electrophilic reagent to the amide compound is not less than 1:1. Specifically, the amide compound can be a compound with the following structural formula:

[0022] .

[0023] A method for treating radioactive waste liquid, which uses the above-mentioned targeting complexing agent.

[0024] Among them, the method further includes a membrane material, the membrane pore size of the membrane material is 2 - 5 nm, and the molecular weight cut-off of the membrane material is 500 Da - 2000 Da (preferably 1000 - 2000 Da). The membrane material should have properties such as appropriate membrane pore size and surface charge density to optimize the retention efficiency of radioactive nuclide complexes.

[0025] Among them, the surface charge density of the membrane material is -80 - +20 mV.

[0026] Among them, the method for treating radioactive waste liquid further includes a step of treating the radioactive waste liquid by light irradiation. The wavelength range of the light irradiation is 100 - 400 nm.

[0027] Specifically, a method for treating radioactive waste liquid, which uses the above-mentioned targeting complexing agent, includes the following steps:

[0028] (1) Add the targeting complexing agent to the radioactive waste liquid, and the dosage is such that the molar ratio of the targeting complexing agent to the nuclide ions in the radioactive waste liquid is 1:1 - 1:5 (preferably 1:2 - 1:5); stir to mix evenly;

[0029] (2) Perform light irradiation treatment on the radioactive waste liquid added with the targeting complexing agent; the wavelength range of the light source used for the light irradiation treatment is 100 - 400 nm;

[0030] (3) After light irradiation for a certain period of time, filter with a membrane material. The membrane material should be selective, only retaining radioactive nuclide complexes and not retaining non-radioactive inorganic salt ions. The resulting membrane concentrate only contains radioactive nuclide complexes, thus simplifying the subsequent treatment steps.

[0031] (4)Chelation release:

[0032] Through white light irradiation (wavelength: 400 nm - 760 nm), the structural formula of the photo-controlled chelating agent is converted from cis ("grasp") to trans ("release"), realizing the dechelation of radionuclides.

[0033] The beneficial effects of the present invention are as follows:

[0034] (1)The targeting chelating agent of the present invention is a photo-controlled chelating agent with reversible structural interconversion, which can directionally increase the morphological size of nuclide ions, and then combine with membrane separation technology with larger pore sizes to achieve high retention of radionuclide complexes, while reducing the retention rate of non-radioactive inorganic salt ions.

[0035] (2)The targeting chelating agent of the present invention can achieve directional chelation and dechelation, facilitating the recycling of the chelating agent and effectively reducing the material and energy consumption in the separation process; it can be controlled by light irradiation to achieve chelation and dechelation, thus realizing recycling, significantly reducing the risk of secondary pollution, and conforming to the core concept of green treatment technology.

[0036] (3)The method for treating radioactive waste liquid of the present invention uses a targeting chelating agent as a radionuclide separation agent and membrane technology as a filtration means to construct a selective chelation-enhanced membrane separation technology; it can efficiently remove radionuclides, while allowing non-radioactive inorganic salt ions such as calcium and magnesium to pass through, reducing the risk of membrane fouling.

[0037] (4)The method for treating radioactive waste liquid of the present invention uses a membrane material with larger membrane pores, which helps to improve the water permeability coefficient of the membrane, thereby reducing the energy consumption and operating cost of the membrane separation process, and has strong anti-fouling ability and can achieve long-term stable operation.

[0038] (5)The method for treating radioactive waste liquid of the present invention is simple to operate, easy to realize automatic control, and does not require the addition of chemical agents, with low operating costs. The present invention has significant application value in the field of efficient pollution control and volume reduction of radioactive waste liquid. This technology avoids the generation of concentrated nuclide solutions from the source and finally achieves the goal of efficient pollution control and volume reduction of low-level radioactive waste liquid. Specific embodiments

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further details the present invention in combination with embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] Unless otherwise specified, the reagents used in the embodiments of the present invention are all commercially available.

[0041] Example 1

[0042] Preparation:

[0043] I. Preparation of azomethyl nucleophile.

[0044] (1) Synthesis of azotoluene.

[0045] In an ice bath, 4-aminotoluene was dissolved in dilute hydrochloric acid. A nitrous acid solution was slowly added while maintaining the temperature at 0 - 5 °C. The reaction mixture was stirred until the formation of diazonium salt. Another portion of 4-aminotoluene was dissolved in sodium hydroxide solution, and the diazonium salt solution was slowly added to the alkaline solution of 4-aminotoluene. The reaction mixture was stirred at room temperature until azotoluene was formed.

[0046] It should be noted that azotoluene can be synthesized by itself or commercially available azotoluene can be used. ;

[0047] (2) Preparation of azomethyl nucleophile.

[0048] In this step, azotoluene was reacted with methyl bromide (CH3Br) to form azomethyl bromide as the nucleophile. Among them, the molar ratio of the added methyl bromide to azotoluene was 2:1. The reaction formula is as follows:

[0049] .

[0050] II. Preparation of amide compounds with leaving groups.

[0051] In this step, the carbon-nitrogen bond in ethylenediaminetetramethylenephosphonic acid was activated; since the carbon-nitrogen bond in ethylenediaminetetramethylenephosphonic acid (EDTAMPA) is relatively stable, a specific activation method is required. In this step, the electrophilic reagent 2-bromoacetyl bromide (BrCH2COBr) was used to react with EDTAMPA in the presence of a catalyst (DCC, N,N'-dicyclohexylcarbodiimide), thereby introducing a leaving group (such as bromoacetyl) on the nitrogen atom. The molar ratio of the added BrCH2COBr to EDTAMPA was 1:1.

[0052] The reaction formula is as follows:

[0053]

[0054] III. Preparation of targeted complexing agent.

[0055] In this step, the EDTAMPA containing a leaving group is coupled with azomethyl iodide in a suitable solvent (such as DMF or DMSO) through a cross-coupling reaction catalyzed by a catalyst such as NaN3 (sodium azide) to synthesize a photo-controlled complexing agent with high selectivity. The reaction temperature is 100 - 120 °C. The molar ratio of the EDTAMPA containing a leaving group to azomethyl iodide is 3:1. The reaction formula is as follows:

[0056] .

[0057] IV. Test the treatment effect of the targeted complexing agent.

[0058] (1) Prepare a simulated radioactive waste liquid: The feed solution used is a solution prepared with deionized water. The nuclide ions in it are prepared from CsNO3 and Sr(NO3), with a concentration of 2000 μg / L (calculated as Cs and Sr). The inorganic salt ions are prepared from CaCl2, MgCl2, and Na2SO4, where the concentration of Ca 2+ / Mg 2+ is 50 μg / L, and the concentration of Na + ions is 100 μg / L. Adjust the pH to 7.0 with a NaHCO3 solution.

[0059] (2) Set the dosing ratio of the targeted complexing agent to the nuclide ions Cs + , Sr 2+ to a molar ratio of 1:2, stir and react for 30 min, and the light wavelength is 400 nm.

[0060] (3) Select a commercial membrane with a cut-off molecular weight of 1000 Da (pore size of 2 nm and surface charge density of the membrane material ranging from -80 to +10 mV), and use a three-group parallel cross-flow device membrane filtration unit produced in China to test the membrane performance. This device includes a variable-frequency diaphragm pump, a temperature control system, and pressure and flow sensors. The cross-flow velocity is not less than 0.1 m / s. It operates in a full-circulation mode.

[0061] (4) Test the retention performance of the complexing-membrane combination technology for radioactive nuclide ions. Determine the (apparent) radioactive nuclide removal rate based on the nuclide ion concentrations in the influent (C f ) and the permeate (C p ).

[0062] R = (1 - C p / C f ) × 100% (1)

[0063] Calculate the permeability coefficient A of the membrane according to the relationship between the water flux (Jw) and the applied pressure (ΔP) (where the osmotic pressure difference is ignored).

[0064] Jw = AΔP (2)

[0065] (5)Contamination resistance performance test: The water tank of the filtration device stores 40 L of a solution similar to the actual system. After the water sample passes through the complexation - membrane module, the effluent is discharged, and the pressure and flow rate are controlled. To maintain a constant temperature throughout the test period, the raw water temperature is maintained at 16 ± 1 °C through a temperature control device, and at the same time, it is monitored in real - time through an electronic thermometer. The changes in the membrane permeation coefficient and the radionuclide retention performance during the test operation are measured.

[0066] (6)Under visible light (450 nm) irradiation, the complexing agent releases radionuclides, and the recovery rate of the complexing agent is calculated.

[0067] The results are shown in Table 1.

[0068] Table 1

[0069] It can be seen that the retention rate of this technology for radionuclides is as high as over 95%, the retention rate for non - radioactive inorganic salt ions is below 10%, and the membrane water permeation coefficient reaches 28 L / m 2 / h / bar, and the light - controlled recovery rate of the complexing agent reaches 97%. This method can achieve the selective separation of radionuclides and has broad application prospects.

[0070] Example 2

[0071] I. Preparation of azomethyl nucleophile.

[0072] (1)Preparation of azomethyl nucleophile.

[0073] In this step, azotoluene (commercially available) reacts with methyl iodide (CH3I) to generate azomethyl iodide (CH2N = NCH3I) as a nucleophile. The molar ratio of methyl iodide to azotoluene is 3:1. The reaction formula is as follows:

[0074]

[0075] II. Preparation of amide compounds with leaving groups.

[0076] In this step, the electrophilic reagent 2 - bromoacetyl bromide (BrCH2COBr) reacts with diethylenetriamine in the presence of a catalyst (copper ions). The molar ratio of diethylenetriamine to BrCH2COBr is 1.5:1. The reaction formula is as follows:

[0077] .

[0078] III. Preparation of targeted complexing agent.

[0079] In this step, the diethylenetriamine containing a leaving group is coupled with azomethyl iodide in a suitable solvent (such as DMF or DMSO), and a catalyst such as NaN3 (cross-coupling reaction catalyzed by sodium azide) is added to synthesize a photosensitive complexing agent with high selectivity. The molar ratio of the diethylenetriamine containing a leaving group to azomethyl iodide is 2:1. The reaction formula is as follows:

[0080] .

[0081] IV. Test the treatment effect of the targeted complexing agent.

[0082] The test method is the same as that in Example 1. Among them, the dosage is that the molar ratio of the targeted complexing agent to the nuclide ions in the radioactive waste liquid is 1:5, the light wavelength during treatment is 100 nm, and the light wavelength during decomplexation is 750 nm; a commercial membrane with a cut-off molecular weight of 2000 Da (pore size of 5 nm and surface charge density of the membrane material of -70 ~ +20 mV) is selected. The test results are shown in Table 2.

[0083] Table 2

[0084] It can be seen that the interception rate of this technology for radioactive nuclides is as high as over 96%, the interception rate for non-radioactive inorganic salt ions is below 12%, and the membrane water permeability coefficient reaches 28 L / m 2 / h / bar, and the recovery rate of the photosensitive complexing agent reaches 96%.

[0085] The present invention utilizes a photosensitive complexing agent to achieve selective complexation of radioactive nuclide ions; by specifically increasing the morphological size of radioactive nuclide ions through the photosensitive complexing agent, it effectively combines with the membrane separation technology with a larger pore size, so as to achieve efficient interception of radioactive nuclide complexes while significantly reducing the interception rate of non-radioactive inorganic salt ions. The key advantage of this technology is that the increased membrane pore size helps to improve the membrane water permeability coefficient, thereby reducing the energy consumption and operating cost during the membrane separation process. In addition, non-radioactive inorganic ions that are prone to scale formation on the membrane surface can pass through the membrane as much as possible, thereby reducing the risk of membrane surface scaling and ensuring the long-term stable operation of the membrane system. The present invention can effectively achieve the goals of efficient pollution control and volume reduction of radioactive waste liquid, and provide an efficient, energy-saving and environmentally friendly solution for the treatment of wastewater containing radioactive nuclides.

[0086] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

[0087] The parts not elaborated in detail in the specification of the present invention belong to the well-known technology in the art. The above embodiments are provided only for the purpose of describing the present invention, rather than limiting the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention shall be covered within the scope of the present invention.

Claims

1. A targeting complexing agent, characterized in that, The molecular structural formula of the target complexing agent is as follows: Among them, R1, R2, R3, and R4 are one or more of a phosphate group, a hydroxyl group, or an amino group.

2. The targeting complexing agent according to claim 1, characterized in that, The molecular structural formula of the target complexing agent is as follows: ； or 。 3. The preparation method of the targeting complexing agent according to claim 1 or 2, characterized in that, The preparation includes the following steps: The target complexing agent can be obtained by carrying out a coupling reaction between an azomethyl nucleophilic reagent and an amide compound with a leaving group in a solvent.

4. The preparation method of the targeting complexing agent according to claim 3, wherein, The azomethyl nucleophilic reagent is an azomethyl halide, and the azomethyl halide is obtained by reacting azotoluene with methyl halide.

5. The preparation method of the targeting complexing agent according to claim 3, wherein The leaving group is a haloacetyl group.

6. The preparation method of the targeting complexing agent according to claim 5, wherein, The preparation method of the amide compound with a leaving group is as follows: The amide compound with a leaving group can be obtained by reacting an electrophilic reagent with an amide compound in the presence of a catalyst.

7. A method for treating radioactive waste liquid, characterized in that, Use the target complexing agent described in claim 1 or 2.

8. The method for treating radioactive waste liquid according to claim 7, characterized in that, The method further includes a membrane material, and the membrane pore size of the membrane material is 2 to 5 nm.

9. The method for treating radioactive waste liquid according to claim 8, wherein The surface charge density of the membrane material is -80 to +20 mV.

10. The method for treating radioactive waste liquid according to claim 7, characterized in that, The method for treating radioactive waste liquid further includes a step of treating the radioactive waste liquid by light irradiation.

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