A soil washing and remediation solubilizer, its preparation method and application

Abstract

The present invention relates to a soil washing and remediation solubilizer, its preparation method and application, belonging to the technical field of soil chemical washing and remediation. The preparation method of the soil washing and remediation solubilizer of the present invention is as follows: (1) Dimethyl ethylenediamine and methyl 2-chloroacrylate are heated under reflux in a solvent, and after cooling, a mixed solution is obtained; (2) Acetone and water are added to the mixed solution and mixed evenly, the pH is adjusted to alkaline, and then lauramide is added for reaction and distillation to obtain an intermediate product; (3) An alkali solution is added to the intermediate product and mixed evenly, tannic acid is continuously added and heated for reaction, and after cooling, recrystallization is carried out to obtain the product. The soil washing and remediation solubilizer prepared by the above preparation method provided by the present invention can significantly improve the removal rate of uranium in uranium-contaminated soil by chemical washing agents, improve the washing and 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 particularly to a soil leaching remediation solubilizer and its preparation method and application. Background Art

[0002] With the increasing demand for energy in society, nuclear energy, as an efficient and clean energy source, has been attracting more and more attention in various industries, and the demand for radioactive nuclide resources such as uranium, plutonium, and polonium has also been increasing continuously. Due to the great difficulty in preventing and controlling pollution in the mining and smelting of radioactive nuclide ores, large-scale development and smelting of nuclide mineral resources will inevitably cause problems such as tailings slag accumulation and ore dust splashing. Heavy metals such as uranium and thorium, as associated minerals, continuously accumulate in the surrounding environment of mining and metallurgical sites, causing varying degrees of soil heavy metal pollution in the region. Uranium, as the main radioactive pollutant element in the process of mining uranium ore and other radioactive nuclide associated minerals, has both radiotoxicity and chemical toxicity, which has an adverse impact on the growth and development of animals and plants in the polluted area around the mining site. These radioactive elements are tightly combined with various minerals and organic matters in the soil and exist for a long time, and may be absorbed by crops through enrichment and enter the food chain, affecting the ecological environment and human health.

[0003] For the treatment of radioactive nuclide contaminated soil, there are generally three categories of methods: physical method, chemical method, and biological method. The chemical leaching method is widely used due to its high removal rate and fast repair rate. However, in the process of chemical leaching reaction, the strong surface interaction between uranium and soil mineral particles and organic matter components limits the further improvement of leaching efficiency. 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 and remediation effect and reduce the impact of soil uranium pollution on the ecological environment.

[0004] Therefore, developing and preparing a soil solubilizer that can effectively improve the leaching and remediation effect of the leaching agent and increase the removal rate of uranium in the soil is of great significance for the safe development of China's nuclear power industry and the protection and remediation of radioactive polluted environments. Summary of the Invention

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

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

[0007] In the first aspect, the present invention provides a preparation method of a soil leaching remediation solubilizer, including the following steps:

[0008] (1) Mix dimethylethylenediamine and methyl 2-chloroacrylate, heat under reflux, and cool to obtain a mixed solution;

[0009] (2) Add acetone and water to the mixed solution, mix well, adjust the pH to alkaline, then add lauroylamide and react, and distill to obtain an intermediate product;

[0010] (3) Add an alkali solution to the intermediate product, mix well, continue to add tannic acid and heat to react, cool, and recrystallize to obtain the soil leaching solubilizer;

[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] The molecular twin-linked surfactant has a hydrophilic "head" and a hydrophobic "tail", and two single-molecule surfactants of the same or different types are connected by a short-chain hydrocarbon. In the present invention, a new molecular twin-linked structure is obtained by a chemical preparation method: using methyl 2-chloroacrylate as a hydrophilic group, connected by dimethylethylenediamine, which can effectively bind to soil particles, weaken the surface tension and double-layer effect of soil particles; at the same time, using lauroylamide as a hydrophobic tail group, it can better promote the dissociation of soil particles from each other, which is beneficial to the dissolution of harmful heavy metals such as uranium inside the soil particles and improve the solubilization effect of the structure; and adding tannic acid to strengthen the chelation effect.

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

[0014] The above specific molar ratios of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid can significantly enhance the solubilization effect of the soil leaching and remediation solubilizer of the present invention on uranium in soil, thereby significantly improving the uranium removal rate in chemical leaching; when the dosage ratios of dimethylethylenediamine, methyl 2-chloroacrylate and tannic acid are outside the limited range, the uranium solubilization and leaching enhancement effects of the prepared soil leaching and remediation solubilizer on uranium-contaminated soil are significantly deteriorated. At the same time, the effect of the specific molecular twin-linked structure of the present invention is significantly better than that of conventional molecular twin-linked surfactants.

[0015] By adding the soil washing and remediation solubilizer provided by the present invention during the chemical washing and remediation process of uranium-contaminated soil, it is beneficial to improve the removal rate of uranium. For the chemical washing reaction of uranium-contaminated soil, the removal rate can be increased by more than 19%. It can enhance the soil remediation washing efficiency, reduce the harm caused by uranium pollution to the ecological environment, and at the same time have less impact on the environment and human body, and has extremely high application value in the protection and renovation of radioactive polluted environments.

[0016] Preferably, the molar ratio of the 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 washing and remediation solubilizer prepared within this ratio range has a better effect on uranium removal and remediation efficiency enhancement in soil washing. Compared with not adding the solubilizer, the uranium removal rate in the soil can be increased by more than 20%.

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

[0019] More preferably, in the step (1), the temperature of the heating reflux 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 lauroylamide to the dimethylethylenediamine is (0.09 - 0.11):(10 - 15).

[0022] As a preferred scheme, in the step (2), lauroylamide is slowly added drop by drop under continuous stirring. Slowly adding drop by drop is beneficial to improving the yield of the intermediate product and the preparation efficiency.

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

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

[0025] In a second aspect, the present invention provides a soil washing and remediation solubilizer prepared by the preparation method of the above soil washing and remediation solubilizer.

[0026] In a third aspect, the present invention provides the application of the above soil washing and remediation solubilizer in the washing and remediation of uranium-contaminated soil. The application includes the following steps:

[0027] Add a leaching agent to the uranium - contaminated soil and treat for 1 - 2 h, add the soil leaching and remediation solubilizer and react for 4 - 5 h, then perform solid - liquid separation to complete the leaching and remediation of the uranium - contaminated soil.

[0028] The present invention provides a method for remediating uranium - contaminated soil, comprising the following steps: grind the uranium - contaminated soil to be treated after adding water and screen it, inject the obtained slurry into a leaching and stirring reactor, and add a chemical leaching agent containing potassium carbonate, potassium bicarbonate, hydrogen peroxide, etc. according to the mass ratio of soil to water of 1:2; after adding the above chemical leaching agent for 1 - 2 h, add the high - efficiency solubilizer to the system, and continue to react for 4 h to achieve a good effect. The soil after leaching is subjected to solid - liquid separation by a high - pressure diaphragm filter press to complete the remediation of the uranium - contaminated soil.

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

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

[0031] As a preferred scheme, the mass ratio of the added amount of the soil leaching and remediation solubilizer to the volume of the leaching agent is 1.6 g / L; add the soil leaching and remediation solubilizer 2 h after adding the chemical leaching agent. At this time, the effect of enhancing the removal of uranium from the soil by the solubilizer reaches the highest.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] Based on the solubilization and chelation principle of surfactants for uranium in contaminated soil, the present invention designs and prepares a soil leaching and remediation solubilizer with a molecular twin - linked structure through an organic chemical reaction, and by regulating the proportion of each reaction component, significantly enhances the chemical leaching and remediation effect of uranium - contaminated soil: under the preferred conditions, for the chemical leaching of uranium - contaminated soil, the uranium removal rate can be increased by 24.04%. At the same time, the preparation process of the present invention is simple. Compared with the traditional chemical leaching method, it can effectively improve the remediation efficiency and restoration effect of contaminated soil, and has less impact on the soil environment and human health, and has high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the soil leaching and remediation solubilizer prepared in Example 1;

[0035] Figure 2Comparison chart of the uranium removal rates when the solubilizers prepared in the examples and comparative examples are used for soil washing and remediation, and the uranium removal rate from the soil without adding a solubilizer. Detailed implementation mode

[0036] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the test methods used in the following embodiments are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, are reagents and materials that can be obtained from commercial channels.

[0037] Example 1

[0038] An embodiment of the solubilizer for soil washing and remediation of the present invention. The preparation method of the solubilizer for soil washing and remediation in this embodiment is as follows:

[0039] S1. Disperse 10 mmol of dimethylethylenediamine and 12 mmol of methyl 2-chloroacrylate in a three-necked flask containing 100 mL of deionized water, stir and reflux under water bath heating at 70 °C for 21 h, and obtain a mixed solution A after cooling to room temperature;

[0040] S2. Add 30 mL of ultrapure water and 70 mL of acetone to the above mixed solution A and mix evenly, then adjust the pH of the system to 9-10 with 0.5 mol / L potassium hydroxide solution to obtain a mixed solution B;

[0041] S3. Slowly add 0.1 mol of lauroylamide dropwise to the mixed solution B with continuous stirring, mix evenly and continue stirring and reacting for 4 h; after the reaction is completed, 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, disperse evenly, then add 40 mg of tannic acid, stir at 800 r / min for 0.5 h, mix evenly and heat in a water bath at 90 °C under constant temperature for 4 h, and obtain a mixed solution D after cooling to room temperature;

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

[0044] Example 2

[0045] An embodiment of the soil washing and remediation solubilizer of the present invention. The preparation method of the soil washing and remediation solubilizer in this embodiment is as follows:

[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, stir and reflux under water bath heating at 70 °C for 21 h, and obtain a mixed solution A after cooling to room temperature;

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

[0048] S3. Slowly dropwise add 0.1 mol of lauramide to the mixed solution B under continuous stirring, mix evenly and continue to stir and react for 4 h; after the reaction is completed, 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, disperse evenly, add 50 mg of tannic acid, stir at 800 r / min for 0.5 h, mix evenly, and heat in a water bath at 90 °C under constant temperature for 4 h. After cooling to room temperature, obtain a mixed solution D;

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

[0051] Example 3

[0052] An embodiment of the soil washing and remediation solubilizer of the present invention. The preparation method of the soil washing and remediation solubilizer in this embodiment is as follows:

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

[0054] S2. Add 30 mL of ultrapure water and 70 mL of acetone to the above mixed solution A, mix evenly, and adjust the pH of the system to 9-10 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 with continuous stirring. After mixing evenly, continue stirring and reacting for 4 h. After the reaction is completed, distill the obtained mixed solution to obtain the intermediate product C.

[0056] S4. Add 100 mL of potassium hydroxide solution with a concentration of 0.08 M to the intermediate product C, stir for 1 h. After dispersing evenly, add 60 mg of tannic acid, stir at 800 r / min for 0.5 h. After mixing evenly, heat in a water bath at a constant temperature of 90 °C for 4 h. After cooling to room temperature, obtain the mixed solution D.

[0057] S5. Place the mixed solution D in a 500 mL round-bottom flask, add 250 mL of cyclohexane, heat at 65 °C for 10 min. Then quickly filter the solution through a 0.22 μm filter membrane into another 500 mL round-bottom flask while it is hot. After the filtered solution cools to room temperature, perform suction filtration through a Buchner funnel. Then heat and dissolve the solid particles dried under reduced pressure on the funnel again in 250 mL of cyclohexane, repeat the above steps twice. Place the obtained solid sample particles in a vacuum drying oven and dry for 24 h to obtain the soil washing and remediation solubilizer.

[0058] Comparative Example 1

[0059] A solubilizer, and its preparation method is as follows:

[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, stir and reflux under water bath heating at 70 °C for 21 h. After cooling to room temperature, obtain the mixed solution A.

[0061] S2. Add 30 mL of ultrapure water and 70 mL of acetone to the above mixed solution A and mix evenly. Then adjust the pH of the system to 9 - 10 with 0.5 mol / L potassium hydroxide solution to obtain the mixed solution B.

[0062] S3. Slowly add 0.1 mol of lauramide dropwise to the mixed solution B with continuous stirring. After mixing evenly, continue stirring and reacting for 4 h. After the reaction is completed, distill the obtained mixed solution to obtain the intermediate product C.

[0063] S4. Add 100 mL of potassium hydroxide solution with a concentration of 0.08 M to the intermediate product C, stir for 1 h. After dispersing evenly, add 10 mg of tannic acid, stir at 800 r / min for 0.5 h. After mixing evenly, heat in a water bath at a constant temperature of 90 °C for 4 h. After cooling to room temperature, obtain the mixed solution D.

[0064] S5. Place the mixture D in a 500 mL round-bottom flask, add 250 mL of cyclohexane, heat at 65 °C for 10 min, and then quickly filter the solution through a 0.22 μm filter membrane into another 500 mL round-bottom flask while it is still hot. After the filtered solution cools to room temperature, filter it by suction through a Buchner funnel. Then, heat and dissolve the solid particles dried under reduced pressure on the funnel again in 250 mL of cyclohexane, repeat the above steps twice, and place the obtained solid sample particles in a vacuum drying oven to dry for 24 h to obtain the solubilizer.

[0065] Comparative Example 2

[0066] A solubilizer, and its preparation method is as follows:

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

[0068] S2. Add 30 mL of ultrapure water and 70 mL of acetone to the above mixture A, mix well, and adjust the pH of the system to 9 - 10 with 0.5 mol / L potassium hydroxide solution to obtain the mixture B.

[0069] S3. Slowly add 0.1 mol of lauroylamide dropwise to the mixture B with continuous stirring, mix well, and continue stirring and reacting for 4 h. After the reaction is completed, distill the obtained mixture to obtain the intermediate product C.

[0070] S4. Add 100 mL of 0.08 M potassium hydroxide solution to the intermediate product C, stir for 1 h, disperse evenly, add 80 mg of tannic acid, stir at 800 r / min for 0.5 h, mix well, and then heat in a water bath at a constant temperature of 90 °C for 4 h. After cooling to room temperature, obtain the mixture D.

[0071] S5. Place the mixture D in a 500 mL round-bottom flask, add 250 mL of cyclohexane, heat at 65 °C for 10 min, and then quickly filter the solution through a 0.22 μm filter membrane into another 500 mL round-bottom flask while it is still hot. After the filtered solution cools to room temperature, filter it by suction through a Buchner funnel. Then, heat and dissolve the solid particles dried under reduced pressure on the funnel again in 250 mL of cyclohexane, repeat the above steps twice, and place the obtained solid sample particles in a vacuum drying oven to dry for 24 h to obtain the solubilizer.

[0072] Comparative Example 3

[0073] A solubilizer, and its preparation method is as follows:

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

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

[0076] S3. Slowly add 0.1 mol of laurylamide dropwise to the mixed solution B with continuous stirring, mix evenly, and continue stirring and reacting for 4 h; after the reaction is completed, 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, disperse evenly, add 50 mg of tannic acid, stir at 800 r / min for 0.5 h, mix evenly, and heat in a water bath at a constant temperature of 90 °C for 4 h. After cooling to room temperature, obtain a mixed solution D;

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

[0079] Comparative Example 4

[0080] A molecular twin-linked surfactant, and its preparation method is as follows:

[0081] S1. Disperse 12.5 mmol of sodium dodecyl sulfate and 15 mmol of sodium dodecylbenzenesulfonate in a three-necked flask containing 30 mL of ultrapure water and 70 mL of acetone, add 10 mmol of ethylenediamine, and continuously stir and reflux under water bath heating at 70 °C for 21 h. After cooling to room temperature, obtain a mixed solution A;

[0082] S2. Adjust the pH of the system to 9 - 10 with 0.5 mol / L potassium hydroxide solution, and distill the mixed solution A 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 to dry for 24 h to obtain a molecular twin-linked surfactant.

[0084] Effect Example

[0085] To explore the application and effect of the soil washing and remediation solubilizer provided by the present invention in washing and remediating uranium-contaminated soil, the following performance tests a and b were carried out.

[0086] Test a. Using the soil washing and remediation solubilizer prepared in Example 2, explore the dosage and washing effect of the soil washing and remediation solubilizer of the present invention in washing and remediating uranium-contaminated soil:

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

[0088] Using the soil washing and remediation solubilizer provided in Example 2, the results of the uranium removal rate in the soil with the dosage of 1.2 g / L, 1.6 g / L, and 2.0 g / L during washing and the comparison with the uranium removal rate without adding the solubilizer are respectively as Figure 2 -(d)(b)(e).

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

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

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

[0092] When using the soil washing and remediation solubilizer of the present invention with a dosage of 1.6 g / L, the improvement of the remediation effect of the uranium-contaminated soil by the chemical washing agent is the most significant.

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

[0094] The uranium-contaminated soil to be treated is ground and screened after adding water, and the obtained slurry is injected into a leaching and stirring reactor. A chemical leaching agent containing sodium carbonate and hydrogen peroxide is added at 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 continues for 4 hours. The soil after leaching is subjected to solid-liquid separation 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 mass ratio of the added solubilizer to the volume of the chemical leaching agent is 1.6 g / L.

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

[0096] Using the soil leaching and remediation solubilizer prepared in Example 1 for leaching reaction for 6 h, the uranium removal rate increased from 63.88% to 83.17%, an increase of 19.29% compared with not adding;

[0097] Using the soil leaching and remediation solubilizer prepared in Example 2 for leaching reaction for 6 h, the uranium removal rate increased from 63.39% to 87.43%, an increase of 24.04% compared with not adding;

[0098] Using the soil leaching and remediation solubilizer prepared in Example 3 for leaching reaction for 6 h, the uranium removal rate increased from 64.21% to 85.54%, an increase of 21.33% compared with not adding.

[0099] Using the solubilizer of Comparative Example 1 for leaching reaction for 6 h, the uranium removal rate increased from 63.88% to 75.31%, an increase of 11.43% compared with not adding;

[0100] Using the solubilizer of Comparative Example 2 for leaching reaction for 6 h, the uranium removal rate increased from 63.88% to 80.63%, an increase of 16.75% compared with not adding;

[0101] Using the solubilizer of Comparative Example 3 for leaching reaction for 6 h, the uranium removal rate increased from 63.88% to 70.97%, an increase of 7.09% compared with not adding;

[0102] Using the molecular twin-linked surfactant of Comparative Example 4 for leaching reaction for 6 h, the uranium removal rate increased from 63.88% to 77.46%, an increase of 13.58% compared with not adding.

[0103] It can be seen by comparison that:

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

[0105] Comparing the comparative example with Comparative Examples 1 and 2, in Comparative Example 1, the amount of methyl 2-chloropropenoate was increased and the amount of tannic acid was decreased, so that the ratio was outside the scope defined in the present invention. Compared with the case without adding a solubilizer, the uranium removal rate was only increased by 11.43%, which was significantly worse than that of the example; in Comparative Example 2, the amounts of dimethylethylenediamine and tannic acid were increased and the amount of methyl 2-chloropropenoate was decreased, so that the ratio was outside the scope defined in the present invention. Compared with the case without adding a solubilizer, the uranium removal rate was increased by 16.75%, which was also worse than the improvement effect of the solubilizer in the example. It can be seen that the dosage ratio of dimethylethylenediamine, methyl 2-chloropropenoate and tannic acid defined in the present invention can significantly improve the synergistic effect of the prepared soil washing and remediation solubilizer on the uranium removal rate in the soil.

[0106] Comparing the comparative example with Comparative Examples 3 and 4: In Comparative Example 3, dimethylethylenediamine and methyl 2-chloropropenoate were replaced by dichloroethane and ethyl propionate, and the prepared solubilizer could increase the uranium removal rate by 7.09% in the washing and remediation of uranium-contaminated soil; in Comparative Example 4, different molecular twin-linked surfactants were prepared using sodium dodecyl sulfate and sodium dodecylbenzenesulfonate, and the uranium removal rate could be increased by 13.58% in the washing and remediation of uranium-contaminated soil. By comparison, it can be seen that the present invention uses methyl 2-chloropropenoate as a hydrophilic group and connects it through dimethylethylenediamine, so that it can effectively bind to soil particles, weaken the surface tension and double-layer effect of soil particles; at the same time, using lauramide as a hydrophobic tail group can promote the dissociation of soil particles from each other, which is more conducive to the dissolution of harmful heavy metals such as uranium inside the soil particles. The solubilization effect on uranium in the soil and thus the synergistic removal effect are more significant, and it can promote the chemical washing agent to more effectively wash and remediate radioactive contaminated soil.

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

Claims

1. A preparation method of a solubilizer for soil washing and remediation, characterized in that, It includes the following steps: (1) Mix dimethylethylenediamine and methyl 2-chloropropenoate, heat under reflux, and cool to obtain a mixed solution; the temperature of the heat under reflux is 60 - 80 °C, and the time is 20 - 24 h; (2) Add acetone and water to the mixed solution, mix well, adjust the pH to alkaline, then add lauramide and react, and distill to obtain an intermediate product; (3) Add an alkali solution to the intermediate product, mix well, continue to add tannic acid and heat to react, cool, and obtain the soil leaching solubilizer through recrystallization; The temperature of the heat reaction is 85 - 95 °C, and the time of the heat reaction is 3 - 4 h; The molar ratio of dimethylethylenediamine, methyl 2-chloropropenoate, and tannic acid is dimethylethylenediamine : methyl 2-chloropropenoate : tannic acid = (10 - 15) : (12 - 18) : (0.023 - 0.036); The solvent for recrystallization is cyclohexane, the heating temperature for recrystallization is 63 - 67 °C, and the crystallization temperature is room temperature.

2. The preparation method of the soil washing and remediation solubilizer according to claim 1, characterized in that, The molar ratio of dimethylethylenediamine, methyl 2-chloropropenoate, and tannic acid is dimethylethylenediamine : methyl 2-chloropropenoate : tannic acid = (12 - 15) : (15 - 18) : (0.029 - 0.036).

3. The preparation method of the soil washing and remediation solubilizer according to claim 1, wherein, In step (2), the volume ratio of acetone to water is (6.5 - 7.5) : (2.5 - 3.5), and the pH adjustment is to adjust to pH = 9 - 10.

4. The preparation method of the soil washing and remediation solubilizer according to claim 1, characterized in that The molar ratio of lauramide to dimethylethylenediamine is (0.09 - 0.11) : (10 - 15).

5. The soil leaching and remediation solubilizer prepared by the preparation method of the soil leaching and remediation solubilizer according to any one of claims 1 - 4.

6. The application of the soil washing and remediation solubilizer as described in claim 5 in the washing and remediation of uranium-contaminated soil, characterized in that, The application includes the following steps: Add a leaching agent to the uranium-contaminated soil and treat for 1 - 2 h, add the soil leaching and remediation solubilizer and react for 4 - 5 h, and perform solid-liquid separation to complete the leaching and remediation of the uranium-contaminated soil.

7. The application of the soil washing and remediation solubilizer as described in claim 6 in the soil washing and remediation of uranium-contaminated soil, characterized in that, The mass ratio of the added soil leaching and remediation solubilizer to the volume of the leaching agent is 1.2 - 2.0 g / L.

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