Soil leaching and repairing solubilizer as well as preparation method and application thereof

Abstract

The invention relates to a soil leaching remediation solubilizer as well as a preparation method and application thereof, and belongs to the technical field of soil chemical leaching remediation. The preparation method of the soil leaching and repairing solubilizer comprises the following steps: (1) heating and refluxing dimethylethylenediamine and 2-chloro-methyl acrylate in a solvent, and cooling to obtain a mixed solution; (2) adding acetone and water into the mixed solution, uniformly mixing, adjusting the pH value to be alkaline, then adding lauramide, reacting, and distilling to obtain an intermediate product; and (3) adding an alkali solution into the intermediate product, uniformly mixing, continuously adding tannic acid, heating, reacting, cooling, and recrystallizing. The soil leaching remediation solubilizer prepared by the preparation method provided by the invention can significantly improve the removal rate of uranium in uranium contaminated soil by a chemical leaching agent, improves the leaching remediation efficiency of radioactive contaminated soil, and has high application value.

Description

Technical Field

[0001] The present invention relates to the technical field of soil chemical leaching and remediation, and in particular to a soil leaching and remediation solubilizing agent, and a preparation method and application thereof. Background Art

[0002] As society's demand for energy continues to increase, nuclear energy, as an efficient and clean energy source, has received more and more attention from all walks of life, and the demand for radioactive nuclide resources such as uranium, plutonium, and polonium has also continued to increase. Due to the difficulty in pollution prevention and control in the mining and smelting of radioactive nuclide ores, the large-scale development and smelting of nuclide mineral resources will inevitably cause problems such as tailings accumulation and ore dust splashing. Heavy metals such as uranium and thorium, as associated minerals, continue to accumulate in the environment around mining and smelting sites, causing varying degrees of heavy metal pollution in the soil in the region. Uranium is the main polluting radioactive element in the mining process of uranium and other radioactive nuclide associated minerals. It has both radiotoxicity and chemical toxicity, and has adverse effects on the growth and development of plants and animals in the contaminated areas around mining. These radioactive elements are closely combined with various minerals and organic matter in the soil for a long time, and may be absorbed by crops into the food chain through enrichment, affecting the ecological environment and human health.

[0003] There are generally three types of treatment technologies for radionuclide contaminated soil: physical, chemical and biological. Chemical leaching is widely used due to its high removal rate and fast remediation rate. However, during the chemical leaching reaction, the strong surface interaction between uranium and soil mineral particles and organic components limits the further improvement of leaching efficiency. In order to effectively reduce the migration and diffusion resistance of uranyl ions at the solid-liquid interface, adding a solubilizer during the leaching process may improve the leaching remediation effect and reduce the impact of soil uranium contamination on the ecological environment.

[0004] Therefore, the development and preparation of a soil solubilizer that can effectively improve the leaching and remediation effect of the eluent and increase the uranium removal rate in the soil is of great significance to the safe development of my country's nuclear power industry and the protection and remediation of the radioactively contaminated environment. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a soil leaching and remediation solubilizing agent and its preparation method and application. The soil leaching and remediation solubilizing agent provided by the present invention can significantly improve the removal rate of uranium in uranium-contaminated soil in conventional chemical leaching, optimize the remediation effect of soil radioactive contamination, and has extremely high application value.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a method for preparing a soil leaching and remediation solubilizing agent, comprising the following steps:

[0008] (1) mixing dimethylethylenediamine and methyl 2-chloroacrylate, heating under reflux, and cooling to obtain a mixed solution;

[0009] (2) adding acetone and water to the mixed solution, mixing, adjusting the pH to alkaline, then adding lauramide to react, and distilling to obtain an intermediate product;

[0010] (3) adding an alkaline solution to the intermediate product, mixing well, continuing to add tannic acid to heat and react, cooling, and recrystallizing to obtain the soil elution solubilizing agent;

[0011] The molar ratio of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid is dimethylethylenediamine:methyl 2-chloroacrylate:tannic acid=(10-15):(12-18):(0.023-0.036).

[0012] Molecular twin surfactants have a hydrophilic "head" and a hydrophobic "tail", and two similar or different types of single-molecule surfactants are connected by short-chain hydrocarbons. The present invention obtains a new molecular twin structure through a chemical preparation method: 2-methyl chloroacrylate is used as a hydrophilic group, connected by dimethylethylenediamine, and can effectively combine with soil particles to reduce the surface tension and double layer effect of soil particles; at the same time, lauramide is used as a hydrophobic tail group to better promote the mutual dissociation of soil particles, which is beneficial to the dissolution of harmful heavy metals such as uranium inside soil particles and enhance the solubilization effect of the structure; and tannic acid is added to strengthen the chelation effect.

[0013] The soil leaching and remediation solubilizing agent provided by the present invention is used in the chemical leaching and remediation of uranium-contaminated soil. It can chelate the uranium elements that are not easily dissolved in soil particles through its chelation, electron transfer and "splitting" effects, and at the same time form an electron bridge between the oxidant of the eluent and the tetravalent uranium, promote the oxidation of insoluble tetravalent uranium into soluble hexavalent uranium, reduce the surface tension between soil particles, force the soil particles to decompose, promote the dissolution of uranium elements from the soil, and comprehensively improve the uranium removal effect in chemical leaching.

[0014] The above-mentioned specific molar ratio of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid can significantly enhance the solubilization effect of the soil leaching and remediation solubilizing agent of the present invention on uranium in the soil, thereby significantly improving the removal rate of uranium in chemical leaching; when the usage ratio of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid is outside the specified range, the uranium solubilization and leaching synergistic effect of the prepared soil leaching and remediation solubilizing agent on uranium contaminated soil is significantly deteriorated. At the same time, the effect of the specific molecular twin structure of the present invention is significantly better than that of conventional molecular twin surfactants.

[0015] By adding the soil leaching and remediation solubilizing agent provided by the present invention during the chemical leaching and remediation process of uranium contaminated soil, it is beneficial to improve the removal rate of uranium. The removal rate of the chemical leaching reaction of uranium contaminated soil can be increased by more than 19%, thereby improving the soil remediation leaching efficiency and reducing the harm caused by uranium pollution to the ecological environment. At the same time, it has little impact on the environment and human body, and has extremely high application value in the protection and remediation of radioactive contaminated environment.

[0016] Preferably, the molar ratio of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid is dimethylethylenediamine:methyl 2-chloroacrylate:tannic acid=(12-15):(15-18):(0.029-0.036).

[0017] The soil leaching and remediation solubilizer prepared within this ratio range has better effects on uranium removal and remediation enhancement in the soil during leaching, and can increase the uranium removal rate in the soil by more than 20% compared to not adding the solubilizer.

[0018] Preferably, in step (1), the heating reflux temperature is 60-80° C. and the time is 20-24 h.

[0019] Further preferably, in the step (1), the heating reflux temperature is 70° C. and the time is 21 h.

[0020] Preferably, in the step (2), the volume ratio of acetone to water is (6.5-7.5):(2.5-3.5), and the pH is adjusted to pH=9-10.

[0021] Preferably, the molar ratio of the lauramide to the dimethylethylenediamine is (0.09-0.11):(10-15).

[0022] As a preferred embodiment, in step (2), lauramide is slowly added dropwise under continuous stirring. Slow dropwise addition is beneficial to improving the yield of the intermediate product and the preparation efficiency.

[0023] Preferably, in step (3), the heating reaction temperature is 85-95° C., and the heating reaction time is 3-4 h.

[0024] Preferably, in the step (3), the solvent for the recrystallization is cyclohexane, the heating temperature for the recrystallization is 63-67° C., and the crystallization temperature is room temperature.

[0025] In a second aspect, the present invention provides a soil leaching and remediation solubilizing agent prepared by the preparation method of the above-mentioned soil leaching and remediation solubilizing agent.

[0026] In a third aspect, the present invention provides the use of the above-mentioned soil leaching and remediation solubilizing agent in leaching and remediation of uranium-contaminated soil, and the use comprises the following steps:

[0027] The leaching agent is added to the uranium contaminated soil for treatment for 1-2 hours, and the soil leaching and remediation solubilizing agent is added for reaction for 4-5 hours, and the solid-liquid separation is performed to complete the leaching and remediation of the uranium contaminated soil.

[0028] The present invention provides a method for repairing uranium contaminated soil, comprising the following steps: grinding and sieving the uranium contaminated soil to be treated with water, injecting the obtained slurry into a leaching and stirring reactor, adding a chemical leaching agent containing potassium carbonate, potassium bicarbonate, hydrogen peroxide, etc. at a soil-water mass ratio of 1:2; after the above chemical leaching agent is added for 1-2 hours, the high-efficiency solubilizing agent is added to the system, and the reaction is continued for 4 hours to achieve a better effect. After the leaching is completed, the soil is separated into solid and liquid by a high-pressure diaphragm filter press to complete the repair of the uranium contaminated soil.

[0029] This application can utilize the above-mentioned soil leaching remediation solubilizer to improve the chemical leaching effect of uranium-contaminated soil, effectively reduce the uranium concentration in the soil, and achieve the purpose of remediating uranium-contaminated soil. It is simple to operate, has low technical requirements for users, and is easy to promote and apply.

[0030] Preferably, the volume ratio of the added mass of the soil leaching and remediation solubilizing agent to the eluting agent is 1.2-2.0 g / L.

[0031] As a preferred solution, the added mass ratio of the soil leaching and remediation solubilizing agent to the volume ratio of the eluent is 1.6 g / L; the soil leaching and remediation solubilizing agent is added 2 hours after the chemical eluent is added. At this time, the solubilizing agent has the highest effect on the removal of uranium in the soil.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention is based on the principle of surfactant solubilization and chelation of uranium in contaminated soil, and a soil leaching and remediation solubilizing agent with a molecular twin structure is prepared by organic chemical reaction design, and the chemical leaching and remediation effect of uranium contaminated soil is significantly enhanced by regulating the distribution ratio of each reaction component: under optimal conditions, the uranium removal rate can be increased by 24.04% when used for chemical leaching of uranium contaminated soil. At the same time, the preparation process of the present invention is simple, and compared with the traditional chemical leaching method, it can effectively improve the remediation efficiency and restoration effect of contaminated soil, and at the same time, it has less impact on the soil environment and human health, and has a high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the soil leaching and remediation solubilizing agent prepared in Example 1;

[0035] Figure 2It is a comparison chart of the uranium removal rate when the solubilizing agent prepared in the examples and comparative examples is used for soil leaching and remediation, and the removal rate of uranium in the soil without adding the solubilizing agent. DETAILED DESCRIPTION

[0036] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with specific examples. The test methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0037] Example 1

[0038] An embodiment of the soil leaching and remediation solubilizing agent of the present invention, the preparation method of the soil leaching and remediation solubilizing agent in this embodiment is:

[0039] S1. Disperse 10 mmol of dimethylethylenediamine and 12 mmol of methyl 2-chloroacrylate in a three-necked flask filled with 100 mL of deionized water, heat in a water bath at 70°C with stirring, condense and reflux for 21 h, and cool to room temperature to obtain a mixed solution A;

[0040] S2. After adding 30 mL of ultrapure water and 70 mL of acetone to the above mixed solution A and mixing evenly, the pH of the system was adjusted to 9 to 10 with 0.5 mol / L potassium hydroxide solution to obtain a mixed solution B;

[0041] S3. Slowly add 0.1 mol of lauramide dropwise to the mixed solution B under constant stirring, mix well, continue stirring, and react for 4 hours; after the reaction, distill the obtained mixed solution to obtain an intermediate product C;

[0042] S4. Add 100 mL of 0.08 M potassium hydroxide solution to the intermediate product C, stir for 1 h, and after uniform dispersion, add 40 mg of tannic acid, stir at 800 r / min for 0.5 h, mix well, heat in a water bath at 90 ° C for 4 h, and cool to room temperature to obtain a mixed solution D;

[0043] S5. Place the mixed solution D in a 500 mL round-bottom flask, add 250 mL cyclohexane, heat at 65 ° C for 10 min, and then filter the solution with a 0.22 μm filter membrane into another 500 mL round-bottom flask while hot; cool the filtered solution to room temperature and filter it through a Buchner funnel; then heat the solid particles on the funnel that have been drained under reduced pressure and dissolve them in 250 mL cyclohexane again, repeat the above steps twice, and place the obtained solid sample particles in a vacuum drying oven and dry them for 24 hours to obtain the soil elution and remediation solubilizer, such as Figure 1 .

[0044] Example 2

[0045] An embodiment of the soil leaching and remediation solubilizing agent of the present invention, the preparation method of the soil leaching and remediation solubilizing agent in this embodiment is:

[0046] S1. Disperse 12.5 mmol of dimethylethylenediamine and 15 mmol of methyl 2-chloroacrylate in a three-necked flask containing 100 mL of deionized water, heat in a water bath at 70°C with stirring, condense and reflux for 21 h, and cool to room temperature to obtain a mixed solution A;

[0047] S2. After adding 30 mL of ultrapure water and 70 mL of acetone to the above mixed solution A and mixing evenly, the pH of the system was adjusted to 9 to 10 with 0.5 mol / L potassium hydroxide solution to obtain a mixed solution B;

[0048] S3. Slowly add 0.1 mol of lauramide dropwise to the mixed solution B under constant stirring, mix well, continue stirring, and react for 4 hours; after the reaction, distill the obtained mixed solution to obtain an intermediate product C;

[0049] S4. Add 100 mL of 0.08 M potassium hydroxide solution to the intermediate product C, stir for 1 h, and after uniform dispersion, add 50 mg of tannic acid, stir at 800 r / min for 0.5 h, mix well, heat in a water bath at 90° C. for 4 h, and cool to room temperature to obtain a mixed solution D;

[0050] S5. Place the mixed solution D in a 500mL round-bottom flask, add 250mL cyclohexane, heat at 65°C for 10min, then filter the solution while hot using a 0.22μm filter membrane into another 500mL round-bottom flask; cool the filtered solution to room temperature and filter it through a Buchner funnel; then heat the solid particles dried on the funnel under reduced pressure again and dissolve them in 250mL cyclohexane, repeat the above steps twice, and place the obtained solid sample particles in a vacuum drying oven and dry them for 24h to obtain the soil leaching and remediation solubilizing agent.

[0051] Example 3

[0052] An embodiment of the soil leaching and remediation solubilizing agent of the present invention, the preparation method of the soil leaching and remediation solubilizing agent in this embodiment is:

[0053] S1. Disperse 15 mmol of dimethylethylenediamine and 18 mmol of methyl 2-chloroacrylate in a three-necked flask filled with 100 mL of deionized water, heat in a water bath at 70°C, stir, condense and reflux for 21 h, and cool to room temperature to obtain a mixed solution A;

[0054] S2. After adding 30 mL of ultrapure water and 70 mL of acetone to the above mixed solution A and mixing evenly, the pH of the system was adjusted to 9 to 10 with 0.5 mol / L potassium hydroxide solution to obtain a mixed solution B;

[0055] S3. Slowly add 0.1 mol of lauramide dropwise to the mixed solution B under constant stirring, mix well, continue stirring, and react for 4 hours; after the reaction, distill the obtained mixed solution to obtain an intermediate product C;

[0056] S4. Add 100 mL of 0.08 M potassium hydroxide solution to the intermediate product C, stir for 1 h, and after uniform dispersion, add 60 mg of tannic acid, stir at 800 r / min for 0.5 h, mix well, heat in a water bath at 90 ° C for 4 h, and cool to room temperature to obtain a mixed solution D;

[0057] S5. Place the mixed solution D in a 500mL round-bottom flask, add 250mL cyclohexane, heat at 65°C for 10min, then filter the solution while hot using a 0.22μm filter membrane into another 500mL round-bottom flask; cool the filtered solution to room temperature and filter it through a Buchner funnel; then heat the solid particles dried on the funnel under reduced pressure again and dissolve them in 250mL cyclohexane, repeat the above steps twice, and place the obtained solid sample particles in a vacuum drying oven and dry them for 24h to obtain the soil leaching and remediation solubilizing agent.

[0058] Comparative Example 1

[0059] A solubilizing agent, the preparation method of which is:

[0060] S1. Disperse 10 mmol of dimethylethylenediamine and 20 mol of methyl 2-chloroacrylate in a three-necked flask containing 100 mL of deionized water, heat in a water bath at 70°C, stir, condense and reflux for 21 h, and cool to room temperature to obtain a mixed solution A;

[0061] S2. After adding 30 mL of ultrapure water and 70 mL of acetone to the above-mentioned mixed solution A and mixing evenly, the pH of the system was adjusted to 9 to 10 with 0.5 mol / L potassium hydroxide solution to obtain a mixed solution B;

[0062] S3. Slowly add 0.1 mol of lauramide dropwise to the mixed solution B under constant stirring, mix well, continue stirring, and react for 4 hours; after the reaction, distill the obtained mixed solution to obtain an intermediate product C;

[0063] S4. Add 100 mL of 0.08 M potassium hydroxide solution to the intermediate product C, stir for 1 h, and after uniform dispersion, add 10 mg of tannic acid, stir at 800 r / min for 0.5 h, mix well, heat in a water bath at 90° C. for 4 h, and cool to room temperature to obtain a mixed solution D;

[0064] S5. Place the mixed solution D in a 500mL round-bottom flask, add 250mL cyclohexane, heat at 65℃ for 10min, then filter the solution while hot using a 0.22μm filter membrane into another 500mL round-bottom flask; cool the filtered solution to room temperature and filter it through a Buchner funnel; then heat the solid particles dried on the funnel under reduced pressure again and dissolve them in 250mL cyclohexane, repeat the above steps twice, and place the obtained solid sample particles in a vacuum drying oven and dry them for 24h to obtain a solubilizing agent.

[0065] Comparative Example 2

[0066] A solubilizing agent, the preparation method of which is:

[0067] S1. Disperse 20mmol of dimethylethylenediamine and 10mol of methyl 2-chloroacrylate in a three-necked flask containing 100mL of deionized water, stir and reflux under heating at 70°C in a water bath for 21h, and cool to room temperature to obtain a mixed solution A;

[0068] S2. After adding 30 mL of ultrapure water and 70 mL of acetone to the above mixed solution A and mixing evenly, the pH of the system was adjusted to 9 to 10 with 0.5 mol / L potassium hydroxide solution to obtain a mixed solution B;

[0069] S3. Slowly add 0.1 mol of lauramide dropwise to the mixed solution B under constant stirring, mix well, continue stirring, and react for 4 hours; after the reaction, distill the obtained mixed solution to obtain an intermediate product C;

[0070] S4. Add 100 mL of 0.08 M potassium hydroxide solution to the intermediate product C, stir for 1 h, and after uniform dispersion, add 80 mg of tannic acid, stir at 800 r / min for 0.5 h, mix well, heat in a water bath at 90° C. for 4 h, and cool to room temperature to obtain a mixed solution D;

[0071] S5. Place the mixed solution D in a 500mL round-bottom flask, add 250mL cyclohexane, heat at 65℃ for 10min, then filter the solution while hot using a 0.22μm filter membrane into another 500mL round-bottom flask; cool the filtered solution to room temperature and filter it through a Buchner funnel; then heat the solid particles dried on the funnel under reduced pressure again and dissolve them in 250mL cyclohexane, repeat the above steps twice, and place the obtained solid sample particles in a vacuum drying oven and dry them for 24h to obtain a solubilizing agent.

[0072] Comparative Example 3

[0073] A solubilizing agent, the preparation method of which is:

[0074] S1. Disperse 12.5mmol of dichloroethane and 15mol of ethyl propionate in a three-necked flask filled with 100mL of deionized water, stir and reflux under 70°C water bath heating for 21h, and cool to room temperature to obtain a mixed solution A;

[0075] S2. After adding 30 mL of ultrapure water and 70 mL of acetone to the above mixed solution A and mixing evenly, the pH of the system was adjusted to 9 to 10 with 0.5 mol / L potassium hydroxide solution to obtain a mixed solution B;

[0076] S3. Slowly add 0.1 mol of lauramide dropwise to the mixed solution B under constant stirring, mix well, continue stirring, and react for 4 hours; after the reaction, distill the obtained mixed solution to obtain an intermediate product C;

[0077] S4. Add 100 mL of 0.08 M potassium hydroxide solution to the intermediate product C, stir for 1 h, and after uniform dispersion, add 50 mg of tannic acid, stir at 800 r / min for 0.5 h, mix well, heat in a water bath at 90° C. for 4 h, and cool to room temperature to obtain a mixed solution D;

[0078] S5. Place the mixed solution D in a 500mL round-bottom flask, add 250mL cyclohexane, heat at 65℃ for 10min, then filter the solution while hot using a 0.22μm filter membrane into another 500mL round-bottom flask; cool the filtered solution to room temperature and filter it through a Buchner funnel; then heat the solid particles dried on the funnel under reduced pressure again and dissolve them in 250mL cyclohexane, repeat the above steps twice, and place the obtained solid sample particles in a vacuum drying oven and dry them for 24h to obtain a solubilizing agent.

[0079] Comparative Example 4

[0080] A molecular twin surfactant, the preparation method of which is as follows:

[0081] S1. 12.5 mmol sodium dodecyl sulfate and 15 mmol sodium dodecylbenzene sulfonate were dispersed in a three-necked flask containing 30 mL ultrapure water and 70 mL acetone, 10 mmol ethylenediamine was added, and the mixture was stirred and refluxed under 70°C water bath heating for 21 h, and then cooled to room temperature to obtain a mixed solution A;

[0082] S2. The pH of the system was adjusted to 9-10 with a 0.5 mol / L potassium hydroxide solution, and the mixed solution A was distilled to obtain a mixture B;

[0083] S3. Add 250 mL of cyclohexane to the mixture B for recrystallization. After repeating 3 times, place the obtained sample in a vacuum drying oven and dry it for 24 hours to obtain a molecular twin surfactant.

[0084] Effect example

[0085] In order to explore the application and effect of the soil leaching and remediation solubilizing agent provided by the present invention in leaching and remediation of uranium contaminated soil, the following performance tests a and b were carried out.

[0086] Test a. The soil leaching and remediation solubilizing agent prepared in Example 2 was used to explore the dosage and leaching effect of the soil leaching and remediation solubilizing agent of the present invention in leaching and remediating uranium contaminated soil:

[0087] The uranium contaminated soil to be treated is ground with water and sieved, and the obtained slurry is injected into a leaching stirring reactor, and a chemical leaching agent containing sodium carbonate and hydrogen peroxide is added in a ratio of 1:2 to the soil-water mass ratio for leaching; 120 minutes after the above chemical leaching agent is added, the soil leaching and remediation solubilizing agent prepared in Example 2 is added to the system, so that the added mass of the solubilizing agent and the volume ratio of the chemical leaching agent are 1.2g / L, 1.6g / L and 2.0g / L respectively; the reaction is continued for 4 hours, and the soil after leaching is separated into solid and liquid by a high-pressure diaphragm filter press to complete the soil remediation. Among them, the initial uranium concentration of the contaminated soil is 1156mg / kg.

[0088] The results of the change of uranium removal rate over time in the soil using the soil leaching remediation solubilizer provided in Example 2 at dosages of 1.2 g / L, 1.6 g / L and 2.0 g / L and the comparison with the uranium removal rate without adding the solubilizer are as follows: Figure 2 -(d)(b)(e).

[0089] By comparison, it can be seen that when the soil leaching and remediation solubilizing agent prepared in Example 2 was added under the above conditions, when the dosage ratio was 1.2 g / L, the uranium removal rate increased from 67.15% to 87.62% after 6 hours of leaching reaction, which was 20.47% higher than that without adding the high-efficiency solubilizing agent;

[0090] When the dosage was 1.6 g / L, the uranium removal rate increased from 63.39% to 87.43% after 6 hours of elution reaction, which was 24.04% higher than that without the addition of the high-efficiency solubilizer.

[0091] When the dosage ratio was 2.0 g / L, the uranium removal rate increased from 65.73% to 87.86% after 6 hours of elution reaction, which was 22.13% higher than that without adding the efficient solubilizer.

[0092] When the soil leaching and remediation solubilizing agent of the present invention is used at a dosage of 1.6 g / L, the improvement of the uranium-contaminated soil remediation effect of the chemical leaching agent is most significant.

[0093] Test b. Comparative study of the synergistic effect of the solubilizers prepared in Examples 1-3 and Comparative Examples 1-4 on the leaching and remediation of uranium contaminated soil:

[0094] The uranium contaminated soil to be treated is ground with water and sieved, and the obtained slurry is injected into the leaching stirring reactor, and a chemical leaching agent containing sodium carbonate and hydrogen peroxide is added in a soil-water mass ratio of 1:2 for leaching; 120 minutes after the addition of the above chemical leaching agent, the above solubilizer is added to the system, and the reaction is continued for 4 hours. After the leaching, the soil is separated from the solid by a high-pressure diaphragm filter press to complete the soil remediation. Among them, the initial uranium concentration of the contaminated soil is 1156 mg / kg, and the volume ratio of the added mass of the solubilizer to the chemical leaching agent is 1.6 g / L.

[0095] The results of the change of uranium removal rate in the soil over time by adding the soil leaching remediation solubilizer prepared in Examples 1-3 during leaching and the comparison with the uranium removal rate without adding the solubilizer are as follows: Figure 2 -(a)(b)(c); The results of the change of uranium removal rate in soil with time using the solubilizer or molecular twin surfactant prepared in Comparative Examples 1-4 during elution and the comparison of uranium removal rate without adding solubilizer as shown in Figure 2 -(f).

[0096] The uranium removal rate was increased from 63.88% to 83.17% by using the soil leaching and remediation solubilizing agent prepared in Example 1 for 6 hours, which was 19.29% higher than that without adding the solubilizing agent.

[0097] The soil leaching and remediation solubilizing agent prepared in Example 2 was used for 6 hours of leaching reaction, and the uranium removal rate increased from 63.39% to 87.43%, which was 24.04% higher than that without the addition.

[0098] The soil leaching and remediation solubilizing agent prepared in Example 3 was used for 6 hours of leaching reaction, and the uranium removal rate was increased from 64.21% to 85.54%, which was 21.33% higher than that when no solubilizing agent was added.

[0099] The uranium removal rate was increased from 63.88% to 75.31% by eluting the solubilizer of comparative example 1 for 6 hours, which was 11.43% higher than that without adding the solubilizer.

[0100] The uranium removal rate was increased from 63.88% to 80.63% by eluting the solubilizer in Comparative Example 2 for 6 hours, which was 16.75% higher than that without adding the solubilizer.

[0101] The uranium removal rate was increased from 63.88% to 70.97% by using the solubilizer of comparative example 3 for 6 hours, which was 7.09% higher than that without adding the solubilizer.

[0102] When the molecular twin surfactant of Comparative Example 4 was used for elution reaction for 6 hours, the uranium removal rate increased from 63.88% to 77.46%, an increase of 13.58% compared with no addition.

[0103] By comparison:

[0104] Compared with the solubilizer or molecular twin surfactant in the comparative example, the soil leaching and remediation solubilizer prepared by the preparation method defined in the present invention in the embodiment, when used in the leaching and remediation of uranium contaminated soil and chemical eluent, can improve the removal rate of uranium in the soil by more than 19.29%, and the effect is more significant, which can significantly improve the leaching and remediation effect of chemical eluent on uranium contaminated soil. Among them, the soil leaching and remediation solubilizer prepared by the preparation method of Example 2 and the eluent have the best effect on improving the uranium removal rate in the soil, reaching an increase of 24.04%, and the uranium removal rate is increased from 63.39% to 87.43%.

[0105] Comparing the embodiment and comparative examples 1 and 2, comparative example 1 increases the amount of methyl 2-chloroacrylate and reduces the amount of tannic acid so that the ratio is outside the scope of the present invention. Compared with not adding a solubilizing agent, the uranium removal rate is only increased by 11.43%, which is significantly worse than the embodiment; comparative example 2 increases the amount of dimethylethylenediamine and tannic acid and reduces the amount of methyl 2-chloroacrylate, so that the ratio is outside the scope of the present invention. Compared with not adding a solubilizing agent, the uranium removal rate is increased by 16.75%, which is also worse than the improvement effect of the solubilizing agent in the embodiment. It can be seen that the dosage ratio of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid defined in the present invention can significantly improve the synergistic effect of the prepared soil leaching and remediation solubilizing agent on the uranium removal rate in the soil.

[0106] Comparative Examples and Comparative Examples 3 and 4: Comparative Example 3 replaces dimethylethylenediamine and methyl 2-chloroacrylate with dichloroethane and ethyl propionate, and the obtained solubilizer can increase the uranium removal rate by 7.09% in the leaching and remediation of uranium contaminated soil; Comparative Example 4 uses sodium dodecyl sulfate and sodium dodecylbenzene sulfonate to prepare different molecular twin surfactants, which can increase the uranium removal rate by 13.58% in the leaching and remediation of uranium contaminated soil. Comparative example 3 shows that the present invention uses methyl 2-chloroacrylate as a hydrophilic group and connects it through dimethylethylenediamine, so that it can effectively combine with soil particles, weaken the surface tension and double electric layer effect of soil particles; at the same time, lauramide is used as a hydrophobic tail group to promote the mutual dissociation of soil particles, which is more conducive to the dissolution of harmful heavy metals such as uranium inside soil particles, and the effect of solubilizing uranium in soil and then enhancing the removal is more significant, which promotes chemical eluents to more effectively leach and remediate radioactive contaminated soil.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a soil leaching and remediation solubilizing agent, characterized in that: The following steps are involved: (1) mixing dimethylethylenediamine and methyl 2-chloroacrylate, heating under reflux, and cooling to obtain a mixed solution; (2) adding acetone and water to the mixed solution, mixing, adjusting the pH to alkaline, then adding lauramide to react, and distilling to obtain an intermediate product; (3) adding an alkaline solution to the intermediate product, mixing well, continuing to add tannic acid to heat and react, cooling, and recrystallizing to obtain the soil elution solubilizing agent; The molar ratio of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid is dimethylethylenediamine:methyl 2-chloroacrylate:tannic acid=(10-15):(12-18):(0.023-0.036).

2. The method for preparing a soil leaching and remediation solubilizing agent according to claim 1, characterized in that: The molar ratio of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid is dimethylethylenediamine:methyl 2-chloroacrylate:tannic acid=(12-15):(15-18):(0.029-0.036).

3. The method for preparing a soil leaching and remediation solubilizing agent according to claim 1, characterized in that: In the step (1), the heating reflux temperature is 60-80°C and the time is 20-24h.

4. The method for preparing a soil leaching and remediation solubilizing agent according to claim 1, characterized in that: In the step (2), the volume ratio of acetone to water is (6.5-7.5): (2.5-3.5), and the pH is adjusted to pH=9-10.

5. The method for preparing a soil leaching and remediation solubilizing agent according to claim 1, characterized in that: The molar ratio of the lauramide to the dimethylethylenediamine is (0.09-0.11):(10-15).

6. The method for preparing a soil leaching and remediation solubilizing agent according to claim 1, characterized in that: In the step (3), the heating reaction temperature is 85-95° C., and the heating reaction time is 3-4 hours.

7. The method for preparing a soil leaching and remediation solubilizing agent according to claim 1, characterized in that: In the step (3), the solvent for the recrystallization is cyclohexane, the heating temperature for the recrystallization is 63-67° C., and the crystallization temperature is room temperature.

8. The soil leaching and remediation solubilizing agent prepared by the method for preparing the soil leaching and remediation solubilizing agent according to any one of claims 1 to 7.

9. Use of the soil leaching and remediation solubilizing agent according to claim 8 in leaching and remediation of uranium contaminated soil, characterized in that: The application comprises the following steps: The leaching agent is added to the uranium contaminated soil for treatment for 1-2 hours, and the soil leaching and remediation solubilizing agent is added for reaction for 4-5 hours, and the solid-liquid separation is performed to complete the leaching and remediation of the uranium contaminated soil.

10. Use of the soil leaching and remediation solubilizing agent according to claim 9 in leaching and remediation of uranium contaminated soil, characterized in that: The volume ratio of the added mass of the soil leaching and remediation solubilizing agent to the leaching agent is 1.2-2.0 g / L.

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