A soil contamination remediation agent and a soil remediation method

Abstract

The application relates to the field of contaminated soil remediation, in particular to a contaminated soil remediation agent and a soil remediation method. The contaminated soil remediation agent comprises the following raw materials in parts by weight: a micelle-iron-based complex 10-15 parts, sodium persulfate 20-30 parts, pH adjusting microspheres 3-5 parts, a biodegradable bacterial agent 1-3 parts, a carrier 40-50 parts and water 8-13 parts; the micelle-iron-based complex is constructed by electrostatic self-assembly of micelles composed of sophorolipid and rhamnolipid and iron-based materials. The remediation agent realizes efficient and green remediation through multi-component cooperation, the micelle-iron-based complex solubilizes and activates sodium persulfate to efficiently oxidize pollutants, the biodegradable bacterial agent decomposes residues, the pH adjusting microspheres stabilize the reaction environment, and the carrier improves dispersibility.

Description

Technical Field

[0001] This application relates to the field of contaminated soil remediation, and in particular to a contaminated soil remediation agent and a soil remediation method. Background Technology

[0002] The organic solid pollutants generated by the iron and steel metallurgical industry during long-term production processes are mainly PAHs, including benzo(a)pyrene, benzo(a)anthracene, benzo(b)fluoranthracene, indo(1,2,3-cd)pyrene and dibenzo(a,h)anthracene, with the highest exceeding the standard by more than 200 times. They are characterized by a wide variety, long storage time, and high degree of pollution.

[0003] Contaminated sites caused by the iron and steel metallurgy industry are characterized by high concentrations and complex types of pollutants, making bioremediation and physical thermal desorption technologies inadequate. Chemical degradation technology has become the preferred alternative.

[0004] Nano-zero-valent iron is a commonly used material in chemical degradation technology. It can not only improve the reactivity of zero-valent iron, but also allow it to flow in the pores of aqueous media, actively attacking pollutants. However, nano-zero-valent iron is prone to agglomeration and enlargement, which reduces its activity and fluidity. Furthermore, its surface can become passivated during catalysis, reducing the reaction rate. It also exhibits vigorous side reactions with water molecules, which greatly limits its application in soil pollution remediation.

[0005] Iron-based materials are made by technicians fixing nano-zero-valent iron onto a carrier with a large specific surface area, strong mechanical properties, adsorption properties and thermal stability to form supported nano-zero-valent iron. They are the most widely used repair materials in chemical redox remediation technology.

[0006] Regarding the aforementioned technologies, the applicant discovered that there is a certain interfacial barrier between iron-based materials and PAHs, which affects the repair efficiency. Summary of the Invention

[0007] To improve the efficiency of remediation of contaminated soil, this application provides a contaminated soil remediation agent, its preparation method, and a soil remediation method.

[0008] Firstly, this application provides a contaminated soil remediation agent, which adopts the following technical solution.

[0009] A contaminated soil remediation agent comprises the following raw materials in parts by weight: 10-15 parts micelle-iron-based composite, 20-30 parts sodium persulfate, 3-5 parts pH-adjusting microspheres, 1-3 parts biodegradable bacterial agent, 40-50 parts carrier, and 8-13 parts water.

[0010] The micelle-iron-based composite is constructed by electrostatic self-assembly of sophorolipid and rhamnolipin as micelles and iron-based materials.

[0011] The core of the pH-adjusting microspheres is citric acid, the middle layer is sodium alginate gel, the outer shell is polylactic acid, and the surface is modified with a polydopamine coating.

[0012] The carrier comprises bentonite and diatomaceous earth in a weight ratio of 3:1;

[0013] The iron-based material is obtained by mixing and grinding industrial zero-valent iron powder, heteroatom source, and carbon source, then carbonizing it, and finally performing surface anti-oxidation modification.

[0014] By adopting the above technical solution, in the micelle-iron-based composite, the combined micelles of sophorolipid and rhamnolipid can solubilize hydrophobic pollutants and promote their desorption from the soil; the iron-based material, through electrostatic self-assembly and improved dispersibility, can efficiently activate sodium persulfate to generate strong oxidizing free radicals, significantly improving the chemical oxidation efficiency. After sodium persulfate rapidly degrades highly toxic pollutants, the biodegradable bacteria further decompose residual substances and intermediate products, forming a synergistic complement of "chemical oxidation + biodegradation," thus avoiding secondary pollution.

[0015] The pH-regulating microspheres employ a multi-layered structure design consisting of a citric acid core, a sodium alginate gel intermediate layer, a polylactic acid outer shell, and a polydopamine coating. This design significantly enhances the pH regulation efficiency of the remediation system. The citric acid core acts as an acidic regulator, precisely replenishing the hydrogen ions required for the reaction. The sodium alginate gel intermediate layer possesses excellent hydrophilicity and slow-release properties, controlling the release rate of citric acid and preventing sudden local pH drops. The polylactic acid outer shell further delays release and is biodegradable, preventing secondary pollution. The polydopamine coating on the surface enhances the adhesion between the microspheres and soil particles, reducing loss and ensuring their continued effectiveness in the remediation area. This stabilizes the optimal pH environment for sodium persulfate oxidation and iron-based catalysis, guaranteeing efficient remediation reactions.

[0016] pH-regulating microspheres maintain the optimal pH environment for the reaction through slow-release action, ensuring sustained catalytic and oxidation efficiency. The carrier enhances the dispersibility of each component, reduces loss, enriches contaminants, and increases local reaction concentration.

[0017] The use of biosurfactants and biodegradable carriers ensures excellent environmental compatibility in the remediation process, and the solution is applicable to soils contaminated with a variety of organic pollutants, balancing remediation efficiency and ecological safety.

[0018] The micelle-iron-based complex and sodium persulfate form a core synergistic system: the iron-based material in the complex can efficiently activate sodium persulfate to generate sulfate free radicals, while the pollutants solubilized by the micelles can directly contact the free radicals, greatly improving the oxidation degradation efficiency. At the same time, the micelles prevent the iron-based material from agglomerating, indirectly enhancing its activation ability for sodium persulfate.

[0019] Biodegradable microbial agents, micelle-iron-based complexes, and sodium persulfate work synergistically: sodium persulfate first degrades highly toxic pollutants to reduce toxicity, creating a suitable environment for the microbial agents; the biosurfactants in the micelles provide nutrients for the microbial agents and promote their reproduction; the microbial agents decompose pollutants and intermediate products remaining from chemical oxidation, forming a complete chain of remediation involving "chemical oxidation + biodegradation".

[0020] pH-regulating microspheres, micelle-iron-based complex, and sodium persulfate synergistically maintain reaction conditions: the microspheres regulate pH through slow release, ensuring the catalytic activity of the iron-based material and the oxidation efficiency of sodium persulfate, and ensuring the continuous and stable synergistic effect of the micelle-iron-based complex and sodium persulfate.

[0021] The synergistic effect among these raw materials makes the overall efficacy of the repair agent far greater than the sum of the individual effects of each component.

[0022] Furthermore, the weight ratio of sophorolipid to rhamnolipin is (2-4):1.

[0023] Furthermore, the weight ratio of sophorolipid to rhamnolipin is 3:1.

[0024] By adopting the above technical solution, and clarifying the weight ratio of sophorolipid to rhamnolipin, the solubilization capacity of micelles for hydrophobic pollutants can be enhanced, the electrostatic self-assembly effect with iron-based materials can be improved, thereby strengthening the activation efficiency of sodium persulfate and promoting the synergistic effect of chemical oxidation and biodegradation. Simultaneously, combined with pH-adjusting microspheres and carriers, the remediation process becomes more efficient, stable, and environmentally friendly.

[0025] Furthermore, the preparation method of the micelle-iron-based composite is as follows:

[0026] 1) Micellar preformation

[0027] Sophorolipid and rhamnolipin were mixed and shaken to obtain a micelle solution;

[0028] 2) Activation of iron-based materials

[0029] Rinse the iron-based material with dilute hydrochloric acid, then dry it;

[0030] 3) Complex self-assembly

[0031] The micelle solution and the activated iron-based material were subjected to ultrasonic self-assembly to obtain a micelle-iron-based composite.

[0032] By adopting the above technical solution, the micelle pre-formation allows sophorolipids and rhamnolipids to fully combine through mixing and oscillation, forming a stable micelle solution with strong solubilizing ability; the iron-based material is activated by rinsing with dilute hydrochloric acid, which can remove surface impurities and oxide layers, and enhance its activity and interaction with micelles; the self-assembly of the composite under ultrasonic conditions can promote the uniform combination of micelles and activated iron-based materials, improve the dispersion and stability of the composite, and thus enhance the activation efficiency of sodium persulfate and the degradation effect of pollutants, making the entire remediation system more efficient.

[0033] Furthermore, after the micelle-iron-based composite is self-assembled, 0.5 wt% of tea saponin by dry weight of the composite is added and ultrasonically dispersed at 40°C and pH 5.5.

[0034] The dry basis weight of the composite refers to the weight of the composite after self-assembly and drying at 60°C for 24 hours.

[0035] By employing the above-mentioned technical solution, adding 0.5 wt% tea saponin after the self-assembly of the micelle-iron-based complex and then ultrasonically dispersing it at 40℃ and pH 5.5 can further enhance the remediation effect. Tea saponin can enhance the stability and solubilization capacity of micelles, and synergistically enhance the effects with sophorolipids and rhamnolipids; the conditions of 40℃ and pH 5.5 can optimize the ultrasonic dispersion effect, promote the full combination of tea saponin and the complex, reduce the aggregation of iron-based materials, improve their dispersibility and activity, thereby enhancing the activation efficiency of sodium persulfate, accelerating the degradation of pollutants, and making the remediation system more efficient and stable.

[0036] Furthermore, the ratio of the micelle solution to the activated iron-based material is 10-15 ml: 1 g.

[0037] By adopting the above technical solution, micelle solution and activated iron-based material are self-assembled at a ratio of 10-15 ml: 1 g. The composite performance is enhanced by precisely controlling the ratio of the two phases, and the specific beneficial effects are as follows:

[0038] Ensuring uniform coating of iron-based materials by micelles: At this formulation, the micelle solution can fully wet the surface of the iron-based material, avoiding localized exposure due to insufficient micelle solution or waste due to micelle aggregation caused by excessive solution. Uniform coating ensures that the active sites on the surface of the iron-based material are orderly covered by micelles, reducing the aggregation of the iron-based material itself and creating a uniform interface for subsequent contact with contaminants and sodium persulfate.

[0039] Optimizing the binding strength of electrostatic self-assembly: A ratio of 10-15 ml to 1 g can balance the charge interaction between micelles and iron-based materials, avoiding weak bonding due to insufficient micelle solution (leading to easy dissociation of the composite) or charge shielding due to excessive solution (weakening the self-assembly driving force). Appropriate binding strength can improve the structural stability of the composite in soil environments and reduce the loss of functional components.

[0040] Synergistic enhancement of remediation system efficiency: The composite formed by reasonable proportion can maximize the synergistic effect of "micelle solubilization-iron-based catalysis" - the solubilization amount of pollutants by micelles is matched with the catalytic activity of iron-based materials, avoiding "excessive solubilization and insufficient catalysis" or "excessive catalysis and insufficient solubilization" caused by imbalance of proportion, ensuring that the free radicals generated by sodium persulfate activation can efficiently degrade the pollutants solubilized by micelles, and further shorten the remediation cycle.

[0041] Furthermore, nano-hydrated manganese oxide is added to the intermediate sodium alginate gel.

[0042] By adopting the above technical solution, adding nano-hydrated manganese oxide to the intermediate sodium alginate gel can enhance the efficacy of pH-regulating microspheres and the overall remediation system through multiple synergistic mechanisms. Specific beneficial effects are as follows: Enhanced pollutant adsorption and pretreatment capacity: Nano-hydrated manganese oxide has a large specific surface area and strong adsorption capacity. It can form stable complexes with heavy metal ions (such as lead, cadmium, and copper) in the soil through its surface hydroxyl groups. Simultaneously, it has a dual function of oxidation and adsorption for some organic pollutants (such as phenols and anilines). After combining with sodium alginate gel, it can form a "pollutant capture zone" around the pH-regulating microspheres, pre-adsorbing and enriching pollutants in the soil, reducing their migration to deeper soil layers, and providing a high-concentration reaction substrate for the subsequent oxidative degradation of the micelle-iron-based complex.

[0043] Synergistic catalysis enhances oxidation efficiency: Nano-hydrated manganese oxide, as a transition metal oxide, can form a "bimetallic catalytic system" with iron-based materials, further activating sodium persulfate to generate sulfate radicals (·SO4). - It generates hydroxyl radicals (·OH) and increases the rate and total amount of free radicals. Simultaneously, its catalytic activity is less affected by pH, and it can function stably within the range regulated by pH-adjustable microspheres, compensating for the activity fluctuations of single iron-based catalysis under extreme pH conditions and enhancing the sustainability of chemical oxidation.

[0044] Enhancing gel structure stability and functional synergy: Nano-hydrated manganese oxide can form hydrogen bonds with the carboxyl groups of sodium alginate through hydroxyl groups, thereby strengthening the mechanical strength of the gel network and reducing the breakage and loss of microspheres in soil pores. Furthermore, it exhibits good compatibility with the acidic environment of the citric acid core, without interfering with its pH-controlled release function. Instead, it can form a relay remediation chain through a multi-step adsorption-catalysis-oxidation reaction, in conjunction with micellar solubilization and iron-based catalysis, significantly improving the remediation efficiency of complex contaminated soils (especially those with organic-heavy metal complex pollution).

[0045] Furthermore, the polylactic acid shell is embedded with dehalogenated bacteria nutrients.

[0046] By employing the above technical solution and embedding dehalogenated bacteria nutrients into the polylactic acid shell, the biodegradation function of the remediation system can be further enhanced, especially for halogenated organic pollutants (such as polychlorinated biphenyls and chlorinated hydrocarbons), resulting in precise synergistic effects. The specific beneficial effects are as follows:

[0047] The polylactic acid (PLA) shell itself is biodegradable, and its embedded dehalogenated nutrients (such as vitamin B1) 12 Specific carbon and nitrogen sources (such as carbon and nitrogen) are slowly released as the shell degrades, which can not only prevent the rapid loss of nutrients, but also continuously provide the key nutrients needed for the growth of dehalogenated bacteria in the soil, significantly improving the activity and reproductive efficiency of dehalogenated bacteria and enhancing their ability to dehalogenate pollutants.

[0048] Simultaneously, this design synergizes with the chemical oxidation process in the system: the micelle-iron-based complex and sodium persulfate first break some halogen bonds through chemical oxidation, reducing the toxicity of pollutants and creating more easily metabolizable substrates for dehalogenating bacteria; while the dehalogenating bacteria can degrade halogenated intermediates that are difficult to completely mineralize through chemical oxidation, forming a relay remediation chain of "chemical bond breaking-biological dehalogenation," significantly improving the completeness of halogenated pollutant degradation. Furthermore, the slow-release properties of the nutrients and pH-regulating microspheres are well-matched, allowing them to continue functioning in a stable pH environment, further expanding the adaptability of the remediation agent to complex contaminated soils.

[0049] Secondly, this application provides a soil remediation method, which adopts the following technical solution.

[0050] A soil remediation method, using any of the contaminated soil remediation agents described above, includes the following steps:

[0051] S1. Dry base mixture

[0052] Micelles-iron-based complexes, sodium persulfate, and a carrier are mixed to obtain a dry material.

[0053] S2. Wet base mixture

[0054] Water, pH-adjusting microspheres, and biodegradable bacterial agents are mixed to obtain a wet material;

[0055] S3. Mixing

[0056] The dry and wet materials are mixed to obtain the repair agent;

[0057] S4. High-pressure rotary jet injection

[0058] Drilling depth: 0.5m below the contaminated layer;

[0059] Injection pressure: 5-8MPa, forming an influence zone with a radius of 1.2m.

[0060] In summary, this application has the following beneficial effects:

[0061] The remediation agent of this application achieves efficient and green remediation through multi-component synergy: micelle-iron-based complex solubilizes and activates sodium persulfate for efficient oxidation of pollutants, biodegradable bacteria decompose residues, pH-adjusting microspheres stabilize the reaction environment, and a carrier enhances dispersibility. Detailed Implementation

[0062] The present application will be further described in detail below with reference to the embodiments.

[0063] Example of raw material and intermediate preparation

[0064] raw material

[0065] It should be noted that: in the following examples, unless otherwise specified, the conditions shall be in accordance with conventional conditions or the manufacturer's recommended conditions; and the raw materials used in the following examples, unless otherwise specified, shall be from commercially available sources.

[0066] Sodium persulfate, industrial grade;

[0067] The carrier is bentonite and diatomaceous earth in a weight ratio of 3:1;

[0068] Biodegradable bacterial agent, consisting of Pseudomonas, Acinetobacter, Mycobacterium, Sphingosomalid, Fibriophyte, and Geobacter in a weight ratio of 1:2:2:1:1:1;

[0069] PLA, medical grade polylactic acid, Mw≈100 kDa, melt index 6-10 g / 10min.

[0070] Preparation Example

[0071] Preparation Example 1

[0072] An iron-based material, the preparation method of which is as follows:

[0073] 1) Ball mill pretreatment

[0074] Industrial zero-valent iron powder, heteroatom source, and carbon source were mixed and ground using a planetary ball mill with zirconia balls as the grinding media. The mass ratio of balls to material was 10:1. High-energy ball milling was performed at 400 rpm for 24 hours, resulting in a particle size of 150-200 nm. The mixture consisted of 100 kg of industrial zero-valent iron powder, a heteroatom source with a weight ratio of 1:12, and a carbon source with a weight ratio of 1:10. The heteroatom source was a mixture of thiourea and sodium phosphate at a weight ratio of 3:1. The carbon source was glucose.

[0075] 2) High-temperature carbonization and heteroatom doping

[0076] In a tube furnace under nitrogen protection, the ground material obtained in step 1) is heated to 600°C at a heating rate of 5°C / min and held at that temperature for 2 hours; then the temperature is further increased to 800°C and held at that temperature for 1 hour to obtain the carbonized material.

[0077] 3) Antioxidant surface modification

[0078] The carbonized material was completely immersed in a polyvinylpyrrolidone solution, ultrasonically treated for 30 minutes, and then vacuum dried at 60°C for 12 hours to obtain the iron-based material.

[0079] Preparation Example 2

[0080] A micelle-iron-based composite, the preparation method of which is as follows:

[0081] 1) Micellar preformation

[0082] Sophorolipid and rhamnolipin were mixed at a weight ratio of 3:1 and shaken at 25°C for 30 min to obtain a micelle solution with a particle size of 50-80 nm.

[0083] 2) Activation of iron-based materials

[0084] The iron-based material obtained in Example 1 was prepared by rinsing with 1% dilute hydrochloric acid and then dried at 60°C.

[0085] 3) Complex self-assembly

[0086] The micelle solution and the activated iron-based material were subjected to ultrasonic self-assembly to form a composite. The ratio of micelle solution to activated iron-based material was 12 ml: 1 g. The ultrasonic power was 40 kHz and the ultrasonic time was 20 min to obtain the micelle-iron-based composite.

[0087] Preparation Example 3

[0088] Unlike Preparation Example 2, the weight ratio of sophorolipid to rhamnolipin in Preparation Example 3 was 2:1.

[0089] Preparation Example 4

[0090] Unlike Preparation Example 2, in Preparation Example 4 the weight ratio of sophorolipid to rhamnolipin was 4:1.

[0091] Preparation Example 5

[0092] Unlike Preparation Example 2, in Preparation Example 5, the ratio of micelle solution to activated iron-based material was 10 ml: 1 g.

[0093] Preparation Example 6

[0094] Unlike Preparation Example 2, in Preparation Example 6 the ratio of micelle solution to activated iron-based material was 15 ml: 1 g.

[0095] Preparation Example 7

[0096] A micelle-iron-based composite, the preparation method of which is as follows:

[0097] 1) Micellar preformation

[0098] Sophorolipid and rhamnolipin were mixed at a weight ratio of 3:1 and shaken at 25°C for 30 min to obtain a micelle solution with a particle size of 50-80 nm.

[0099] 2) Activation of iron-based materials

[0100] The iron-based material obtained in Example 1 was prepared by rinsing with 1% dilute hydrochloric acid and then dried at 60°C.

[0101] 3) Complex self-assembly

[0102] The micelle solution and the activated iron-based material were subjected to ultrasonic self-assembly to form a composite. The ratio of micelle solution to activated iron-based material was 12 ml: 1 g. The ultrasonic power was 40 kHz and the ultrasonic time was 20 min to obtain the micelle-iron-based composite.

[0103] 1) Post-processing

[0104] Dissolve tea saponin powder (purity ≥85%) in warm water at 40℃ to a concentration of 10wt%, then add 0.1wt% NaCl to obtain the mother liquor;

[0105] The amount of tea saponin used is calculated based on the dry weight of the complex. For example: 1 kg complex → add 5 g of tea saponin → take 50 g of mother liquor (containing 5 g of tea saponin).

[0106] Gradient mixing: Add tea saponin mother liquor dropwise to the complex suspension (speed ≤ 5 mL / min), and simultaneously mechanically stir (200 rpm) + sonicate (40 kHz, 100 W).

[0107] Preparation Example 8

[0108] A pH-adjusting microsphere, the preparation method of which is as follows:

[0109] 1) Kernel preparation

[0110] Citric acid powder (200 mesh) was mixed with nano-silica (5 wt%) and spray-dried to form spherical cores with a particle size of 80-100 μm (inlet temperature 180℃, outlet temperature 80℃).

[0111] 2) Sodium alginate coating

[0112] The core is immersed in a 2% sodium alginate solution, and 0.1 M CaCl2 is added to solidify it, forming a hydrogel layer;

[0113] 3) PLA outer casing

[0114] Fluidized bed coating was used: airflow velocity 1.5 m / s, atomization pressure 0.8 bar; PLA solution (dichloromethane: PLA = 9:1) was sprayed until the weight gain was 30%;

[0115] 4) Polydopamine modification

[0116] Immerse in 2 mg / mL dopamine-Tris buffer (pH=8.5), shake for 12 h to form an adhesion layer, wash and dry.

[0117] Preparation Example 9

[0118] Unlike Preparation Example 8, in Preparation Example 9, 5% nano-hydrated manganese oxide was added to the sodium alginate solution in 2) sodium alginate coating.

[0119] Preparation Example 10

[0120] Unlike Preparation Example 8, in Preparation Example 10, a dehalogenated bacteria nutrient was added to the PLA solution encapsulated in the PLA shell (3). The dehalogenated bacteria nutrient consisted of sodium lactate and vitamin B. 12 The mixture is composed of components at a mass ratio of 1000:1, and after ball milling, it is added to the PLA solution.

[0121] Example

[0122] Examples 1-3

[0123] A soil remediation method includes the following steps:

[0124] S1. Dry base mixture

[0125] According to the proportions in Table 1, the micelle-iron-based composite, sodium persulfate, and carrier are mixed to obtain the dry material;

[0126] S2. Wet base mixture

[0127] Water, pH-adjusting microspheres, and biodegradable bacterial agents are mixed to obtain a wet material;

[0128] S3. Mixing

[0129] The dry and wet materials are mixed to obtain the repair agent;

[0130] S4. High-pressure rotary jet injection

[0131] Drilling depth: 0.5m below the contaminated layer;

[0132] Injection pressure: 6MPa, forming an influence zone with a radius of 1.2m.

[0133] Table 1. Raw material ratios for Examples 1-3 (kg)

[0134]

[0135] Among them, the micelle-iron-based complex was prepared in Example 2, and the pH-adjusting microspheres were prepared in Example 8.

[0136] Examples 4-8

[0137] Unlike Example 2, the micelle-iron-based composites in Examples 4-8 were derived from Preparation Examples 3-7, respectively.

[0138] Examples 9-10

[0139] Unlike Example 8, the pH-adjusting microspheres in Examples 9-10 were derived from Preparation Examples 9-10, respectively.

[0140] Comparative Example

[0141] Comparative Example 1

[0142] Unlike Example 1, in Comparative Example 1, the micelle-iron composite was replaced with an equal amount of iron-based material from Preparation Example 1.

[0143] Performance testing

[0144] Referring to the standard HJ834-2017 "Determination of Semi-volatile Organic Compounds in Soil and Sediments by Gas Chromatography-Mass Spectrometry", a gas chromatography-mass spectrometry (single quadrupole) instrument was used to sample and test the soil before and after remediation. The contaminated soil was a contaminated site of a steel company. The pollutant content in the soil before remediation was benzo(a) anthracene: 30.8 mg / kg, benzo(b) fluoranthene: 28.3 mg / kg, benzo(a) pyrene: 19.8 mg / kg, indo(1,2,3-cd) pyrene: 28.6 mg / kg, and dibenzo(a,h) anthracene: 60.6 mg / kg. Samples were taken and tested 5 months after remediation. The results of the pollutant content test in the soil after remediation are shown in Table 2.

[0145] Table 2 Performance Test Results

[0146]

[0147]

[0148]

[0149] Based on Examples 1-10 and Comparative Example 1, and in conjunction with Table 2, it can be seen that the pollutant content of the remediated soil in Examples 1-10 is lower and the remediation effect is better. This indicates that the soil remediation agent and remediation method obtained in this application have a better remediation effect on the contaminated soil in the iron and steel metallurgical industry and are suitable for industrial development.

[0150] Combining Example 1 and Comparative Example 1, and referring to Table 2, it can be seen that the pollutant content of the remediated soil in Example 1 is lower, and the remediation effect is better. This indicates that surface modification of iron-based materials with micelles is beneficial to improving the remediation effect on contaminated soil. This may be because, in the micelle-iron-based composite, the combination of sophorolipids and rhamnolipins can solubilize hydrophobic pollutants and promote their desorption from the soil; the iron-based material, after electrostatic self-assembly and improved dispersibility, can efficiently activate sodium persulfate to generate strong oxidizing free radicals, significantly improving the chemical oxidation efficiency. After sodium persulfate rapidly degrades highly toxic pollutants, the biodegrading agent further decomposes residual substances and intermediate products, forming a synergistic complement of "chemical oxidation + biodegradation," avoiding secondary pollution.

[0151] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A contaminated soil remediation agent, characterized in that, The raw materials include the following parts by weight: micelle-iron-based complex 10-15 parts, sodium persulfate 20-30 parts, pH-adjusting microspheres 3-5 parts, biodegradable bacterial agent 1-3 parts, carrier 40-50 parts, and water 8-13 parts. The micelle-iron-based composite is constructed by electrostatic self-assembly of sophorolipid and rhamnolipin as micelles and iron-based materials. The preparation method is as follows: 1) Micellar preformation Sophorolipid and rhamnolipin were mixed and shaken to obtain a micelle solution; 2) Activation of iron-based materials Rinse the iron-based material with dilute hydrochloric acid, then dry it; 3) Complex self-assembly Micelle solution and activated iron-based material were subjected to ultrasonic self-assembly to obtain micelle-iron-based composites. The core of the pH-adjusting microspheres is citric acid, the middle layer is sodium alginate gel, the outer shell is polylactic acid, and the surface is modified with a polydopamine coating. The carrier comprises bentonite and diatomaceous earth in a weight ratio of 3:1; The iron-based material is obtained by mixing and grinding industrial zero-valent iron powder, heteroatom source, and carbon source, then carbonizing it, and then performing surface anti-oxidation modification; wherein, the heteroatom source is a mixture of thiourea and sodium phosphate in a weight ratio of 3:1; and the carbon source is glucose.

2. The contaminated soil remediation agent according to claim 1, characterized in that, The weight ratio of sophorolipid to rhamnolipin is (2-4):

1.

3. The contaminated soil remediation agent according to claim 2, characterized in that, The weight ratio of sophorolipid to rhamnolipin is 3:

1.

4. The contaminated soil remediation agent according to claim 1, characterized in that, After the micelle-iron-based composite is self-assembled, 0.5 wt% of tea saponin by dry weight of the composite is added and ultrasonically dispersed at 40°C and pH 5.

5.

5. The contaminated soil remediation agent according to claim 1, characterized in that, The ratio of the micelle solution to the activated iron-based material is 10-15 ml: 1 g.

6. The contaminated soil remediation agent according to claim 1, characterized in that, Nano-hydrated manganese oxide is added to the intermediate sodium alginate gel.

7. The contaminated soil remediation agent according to claim 1, characterized in that, The polylactic acid shell is embedded with dehalogenated bacteria nutrients.

8. A soil remediation method, characterized in that, Remediation of contaminated soil using any one of the remediation agents described in claims 1-7 includes the following steps: S1. Dry base mixture The micelle-iron-based composite, sodium persulfate, and carrier were mixed to obtain the dry material; S2. Wet base mixture Water, pH-adjusting microspheres, and biodegradable bacterial agents are mixed to obtain a wet material; S3. Mixing The dry and wet materials are mixed to obtain the repair agent; S4. High-pressure rotary jet injection Drilling depth: 0.5m below the contaminated layer; Injection pressure: 5-8MPa, forming an influence zone with a radius of 1.2m.

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