Preparation Method and Application of an Oil-Polluted Soil Remediation Agent

Abstract

The present invention discloses a preparation method and an application of a soil remediation agent for petroleum-contaminated soil. The preparation method includes: (1) uniformly mixing glass powder, titanium dioxide powder, copper powder, and iron powder, then performing sintering treatment in a protective atmosphere, cooling to room temperature after completion, and then crushing and screening the sintered product to obtain a precursor. (2) Subjecting the precursor to surface treatment in hydrofluoric acid, washing and drying after completion to obtain the soil remediation agent. The application includes: (i) placing the petroleum-contaminated soil, the remediation agent, and water in a reaction vessel, stirring evenly, sealing the vessel, and heating and insulating, and obtaining pretreated soil after completion. (ii) Spreading out the pretreated soil and performing light treatment, and magnetically adsorbing and separating the remediation agent after completion to obtain the remediated soil. The remediation agent prepared by the above method of the present invention can not only more rapidly reduce the petroleum content in the soil, but also the remediation agent can be regenerated and reused repeatedly.

Description

Technical Field

[0001] The present invention relates to the technical field of contaminated soil treatment, and particularly to a preparation method and application of an oil-contaminated soil remediator. Background Art

[0002] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Oil is called the blood of industry and black gold, and is an indispensable production material for the development of modern society. Oil needs to go through processes such as mining, storage and transportation, refining and processing, and transportation. In these processes, problems often occur that oil enters the soil and causes pollution. On the one hand, the soil into which oil enters will have problems such as reduced water permeability and poor air permeability, which will in turn cause crop yield reduction or even death. This is because oil has poor water solubility and strong adhesion. After entering the soil, it will block the gaps between soil particles, resulting in poor water absorption of the soil and changing the soil structure. On the other hand, the oil in the soil will also cause water pollution when it enters groundwater and rivers with rainfall, etc. Therefore, once the soil is contaminated with oil, it needs to be treated in time to reduce the resulting hazards.

[0004] At present, the treatment technologies for oil-contaminated soil mainly include physicochemical remediation, microbial remediation, phytoremediation, etc. The latter two methods are more environmentally friendly and pollution-free, and can also completely degrade pollutants. However, the remediation time of these two methods is relatively long, often taking several months or even longer. For soils that are severely contaminated and need to be treated urgently, the above-mentioned bioremediation technologies cannot meet the requirements. Therefore, it is necessary to explore new treatment technologies for oil-contaminated soil. Summary of the Invention

[0005] The present invention provides a preparation method and application of an oil-contaminated soil remediator. The remediator prepared by this method can not only more quickly reduce the oil content in the soil, facilitating the rapid treatment of contaminated soil, but also the remediator can be regenerated and reused repeatedly. Specifically, the technical solution of the present invention is as follows.

[0006] First, the present invention discloses a preparation method of an oil-contaminated soil remediator, including the following steps:

[0007] (1) Mix glass powder, titanium dioxide powder, copper powder, and iron powder evenly and then perform sintering treatment in a protective atmosphere. After completion, cool to room temperature, and then crush and screen the sintered product to obtain a precursor.

[0008] (2) Place the precursor in hydrofluoric acid for surface treatment. After completion, wash and dry it to obtain the soil remediation agent.

[0009] Further, in step (1), the mass ratio of the glass powder, titanium dioxide powder, copper powder, and iron powder is 1.5 - 2:0.5 - 0.62:0.3 - 0.5:0.22 - 0.35. Optionally, the fineness of each of the above powders is 80 - 200 mesh. The glass powder can also be made from waste glass, thereby reducing costs and achieving waste recycling.

[0010] Further, in step (1), the protective atmosphere includes at least one of nitrogen, argon, etc.

[0011] Further, in step (1), the temperature of the sintering treatment is not higher than 800°C and not lower than the melting temperature of the glass powder. The time of the sintering treatment is 20 - 30 min. Optionally, the melting temperature of the glass powder is 500 - 780°C.

[0012] Further, in step (1), the particle size of the precursor is 1 - 3 mm.

[0013] Further, in step (2), the ratio of the precursor to hydrofluoric acid is 1 g:5 - 15 ml. Optionally, the mass fraction of the hydrofluoric acid is 10 - 20%.

[0014] Further, in step (2), the time of the surface treatment is 20 - 40 min.

[0015] Further, in step (2), after washing with clear water and drying to constant weight, the soil remediation agent is obtained.

[0016] Secondly, the application of the remediation agent obtained by the preparation method of the present invention in the treatment of petroleum - contaminated soil. Optionally, the method of the application includes the following steps:

[0017] (i) Place the petroleum - contaminated soil, the above - mentioned soil remediation agent, and water in a reaction vessel, stir evenly, seal the vessel, and heat for heat preservation. After completion, obtain the pretreated soil.

[0018] (ii) Spread out the pretreated soil and carry out light treatment. After completion, magnetically adsorb and separate the remediation agent to obtain the remediated soil.

[0019] Further, in step (i), the ratio of the soil, soil remediation agent, and water is 10 parts by weight:4 - 7 parts by weight:2 - 3.2 parts by weight.

[0020] Further, in step (i), the heating temperature is 180 - 240 °C, and the heat preservation time is 1.5 - 3 hours. Optionally, the pressure in the reaction vessel is maintained at 0.2 - 0.5 MPa.

[0021] Further, in step (ii), the thickness of the pre-treated soil after spreading out is not more than 2 cm.

[0022] Further, in step (ii), the time of the light treatment is not less than 5 days. Optionally, the light includes sunlight, artificial light, etc. Additionally, sunlight can be used during the day, artificial light can be used at night, or artificial light can be used when insufficient light is caused by cloudy days. The light source power of the artificial light is not less than 500 W.

[0023] Further, in step (ii), the soil is turned over every 5 - 7 hours so that the lower soil can receive light and the petroleum molecules in it can be photocatalytically degraded.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0025] The remediation agent for treating petroleum-contaminated soil prepared by the present invention is formed by sintering glass powder, titanium dioxide powder, copper powder, and iron powder. After sintering, the titanium dioxide powder, copper powder, and iron powder are distributed in the matrix formed by the glass. During this process, iron and copper elements are doped into the titanium dioxide, thereby increasing the lattice defects of the titanium dioxide, increasing the oxygen vacancies, and improving the response ability of the titanium dioxide to visible light. After further treatment with hydrofluoric acid, on the one hand, it can make the exposed area and exposed amount of the titanium dioxide particles on the surface of the matrix larger. On the other hand, after the iron powder particles on the surface of the matrix are removed by hydrofluoric acid, it also helps more titanium dioxide particles to be exposed, thus more contributing to accelerating the photocatalytic degradation of petroleum. Further, the present invention proposes a treatment method for petroleum-contaminated soil suitable for the above-mentioned remediation agent, that is: first, the viscosity of the petroleum-contaminated soil containing the remediation agent is reduced under high temperature and high pressure conditions. During this process, the petroleum molecules in the soil are broken under the catalysis of copper and iron on the remediation agent, reducing the molecular weight of the petroleum molecules while reducing the soil adhesion degree, facilitating subsequent photocatalytic degradation. After completing the above pretreatment, the soil is further subjected to light treatment, and the petroleum molecules are photocatalytically degraded into water and carbon dioxide under the action of titanium dioxide on the surface of the remediation agent, realizing the remediation of petroleum-contaminated soil. At the same time, due to the good light transmittance of the glass matrix, the remediation agent also serves as a light transmission channel, increasing the amount of light entering the soil, enabling the surface of the remediation agent located in the soil to also utilize light for photocatalytic degradation of petroleum molecules, and promoting the efficiency of the remediation agent.

[0026] In addition, the iron powder distributed in the matrix can also enable the repair agent of the present invention to achieve magnetic recovery, which is convenient for reuse. When the degradation effect is reduced, the repair agent can also be reduced by hydrogen, sodium borohydride, etc., so that copper oxide and iron oxide can be transformed into copper element to play a role. The repair agent can also be treated with hydrofluoric acid again to expose more titanium dioxide, copper and iron, so as to make up for the problem of reduced repair effect caused by the loss of titanium dioxide, copper, iron, etc. on the surface of the repair agent caused by the peeling. The repair agent of the present invention has both a pretreatment effect on petroleum molecules in the soil and a photocatalytic degradation effect on petroleum molecules. The two cooperate with each other to effectively improve the repair efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein:

[0028] Figure 1 This is a sample picture of the soil remediation agent of the following Example 1.

[0029] Figure 2 This is a picture of the petroleum contaminated soil sample being remediated in Example 1 below. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0031] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions.

[0032] In addition, any method and material similar or equivalent to the content described above can be applied to the method of the present invention. The present invention is further described in conjunction with the accompanying drawings and specific implementation methods. The preferred implementation methods and materials described in the present invention are only for demonstration purposes.

[0033] Embodiment 1:

[0034] 1. A method for preparing a petroleum-contaminated soil remediation agent, comprising the following steps:

[0035] (1) Mix glass powder, titanium dioxide powder, copper powder, and iron powder with a fineness of 150 mesh evenly according to a mass ratio of 1.8:0.55:0.4:0.27, and then heat it to 750 °C at a heating rate of 10 °C / min in a nitrogen atmosphere and hold for 20 min. The melting temperature of the glass powder is about between 670 and 700 °C. After the sintering is completed, cool it to room temperature, then crush the sintered product, and then screen out the particulate matter with a particle size distribution between 1 and 3 mm to obtain the precursor for standby.

[0036] (2) Mix the precursor with 10% hydrofluoric acid by mass according to a ratio of 1 g:12 ml, let it stand for 30 min for surface treatment. After completion, wash it with clean water to remove the residual hydrofluoric acid, and then dry it to constant weight at 100 °C to obtain the soil remediation agent, as Figure 1 shown.

[0037] 2. A method for treating oil-contaminated soil, comprising the following steps:

[0038] (i) Mix the oil-contaminated soil (from a certain oilfield, with an oil content of 10738 mg / kg), the remediation agent prepared in this example, and clean water evenly according to a ratio of 10 parts by weight:6 parts by weight:3 parts by weight (as Figure 2 shown), then load it into a high-pressure reactor, seal the reactor, and then heat it to 210 °C and hold for 3 hours. The pressure of the reactor is set to 0.35 MPa. After completion, obtain the pretreated soil.

[0039] (ii) Spread the pretreated soil to form a soil layer with an average thickness of 1 cm, and then irradiate it with a 500 W lamp. The distance between the light source and the soil layer is 40 cm. Continuously irradiate for 192 hours under the above light conditions, and turn the soil every 6 hours. After completion, magnetically adsorb and separate the remediation agent in the soil to obtain the repaired soil.

[0040] Calculate the oil degradation rate of the oil-contaminated soil in this example. The calculation formula is (m 1 - m 2 ) / m 1 × 100%, where m 1 is the content of oil in the initial soil (10738 mg / kg), and m 2 is the content of oil in the repaired soil in this example. The result is 90.67%.

[0041] Example 2:

[0042] 1. A preparation method of an oil-contaminated soil remediation agent, comprising the following steps:

[0043] (1) Mix glass powder, titanium dioxide powder, copper powder, and iron powder with a fineness of 200 mesh evenly according to the mass ratio of 1.5:0.5:0.3:0.22, and then heat it to 800 °C at a heating rate of 10 °C / min in a nitrogen atmosphere and hold for 20 min. The melting temperature of the glass powder is about between 750 and 780 °C. After the sintering is completed, cool it to room temperature, then crush the sintered product, and then screen out the particulate matter with a particle size distribution between 1 and 3 mm to obtain the precursor for standby.

[0044] (2) Mix the precursor with 20% hydrofluoric acid by mass according to the ratio of 1 g:5 ml, let it stand for 20 min for surface treatment, and after completion, wash it with clean water to remove the residual hydrofluoric acid, and then dry it to constant weight at 80 °C to obtain the soil remediation agent.

[0045] 2. A method for treating oil-polluted soil, comprising the following steps:

[0046] (i) Mix the oil-polluted soil (from a certain oilfield with an oil content of 10738 mg / kg), the remediation agent prepared in this example, and clean water evenly according to the ratio of 10 parts by weight:4 parts by weight:2 parts by weight, then load them into a high-pressure reactor, seal the reactor, and then heat it to 180 °C and hold for 2.5 hours. The pressure of the reactor is set to 0.5 MPa. After completion, obtain the pretreated soil.

[0047] (ii) Spread the pretreated soil to form a soil layer with an average thickness of 2 cm, and then irradiate it with a 800 W lamp. The light source is 40 cm away from the soil layer. Continuously irradiate for 120 hours under the above light conditions, and turn the soil every 5 hours. After completion, magnetically adsorb and separate the remediation agent in the soil to obtain the repaired soil.

[0048] Calculate the oil degradation rate of the oil-polluted soil in this example. The calculation formula is (m 1 - m 2 ) / m 1 × 100%, where m 1 is the oil content in the initial soil (10738 mg / kg), and m 2 is the oil content in the repaired soil of this example. The result is 87.54%.

[0049] Example 3:

[0050] 1. A preparation method of an oil-polluted soil remediation agent, comprising the following steps:

[0051] (1) Mix glass powder, titanium dioxide powder, copper powder, and iron powder with a fineness of 80 mesh evenly according to a mass ratio of 2:0.62:0.5:0.35, then heat it to 700 °C at a heating rate of 10 °C / min in a nitrogen atmosphere and hold for 20 min. The melting temperature of the glass powder is about between 500 and 540 °C. After sintering, cool it to room temperature, then crush the sintered product, and then screen out the particles with a particle size distribution between 1 and 3 mm to obtain the precursor for standby.

[0052] (2) Mix the precursor with 10% hydrofluoric acid by mass according to a ratio of 1 g:15 ml, let it stand for 40 min for surface treatment, then wash it with clean water to remove the residual hydrofluoric acid, and then dry it to constant weight at 80 °C to obtain the soil remediation agent.

[0053] 2. A method for treating oil-contaminated soil, comprising the following steps:

[0054] (i) Mix the oil-contaminated soil (from a certain oilfield with an oil content of 10738 mg / kg), the remediation agent prepared in this example, and clean water evenly according to a ratio of 10 parts by weight:7 parts by weight:3.2 parts by weight, then load them into a high-pressure reactor, seal the reactor, and then heat it to 240 °C and hold for 1.5 hours. The pressure of the reactor is set to 0.2 MPa. After completion, obtain the pretreated soil.

[0055] (ii) Spread out the pretreated soil to form a soil layer with an average thickness of 1 cm, then irradiate it with a 800 W lamp. The light source is 40 cm away from the soil layer. Continuously irradiate for 168 hours under the above light conditions, and turn over the soil every 7 hours. After completion, magnetically adsorb and separate the remediation agent in the soil to obtain the remediated soil.

[0056] Calculate the oil degradation rate of the oil-contaminated soil in this example. The calculation formula is (m 1 - m 2 ) / m 1 × 100%, where m 1 is the oil content in the initial soil (10738 mg / kg), and m 2 is the oil content in the remediated soil of this example. The result is 91.86%.

[0057] Example 4:

[0058] A method for treating oil-contaminated soil is the same as Example 1 above, except that the soil remediation agent in this example is prepared by the following method:

[0059] (1) Mix glass powder with a fineness of 150 mesh, titanium dioxide powder, and iron powder evenly according to a mass ratio of 1.8:0.55:0.27, and then heat it to 750 °C at a heating rate of 10 °C / min in a nitrogen atmosphere and hold for 20 min. The melting temperature of the glass powder is about between 670 and 700 °C. After the sintering is completed, cool it to room temperature, then crush the sintered product, and then screen out the particulate matter with a particle size distribution between 5 and 7 mm to obtain the precursor for standby.

[0060] (2) Mix the precursor with 10% hydrofluoric acid by mass according to a ratio of 1 g:12 ml, let it stand for 30 min for surface treatment, after completion, wash it with clear water to remove the residual hydrofluoric acid, and then dry it to constant weight at 100 °C to obtain the soil remediation agent.

[0061] Calculate the petroleum degradation rate of the petroleum-contaminated soil in this example. The calculation formula is (m 1 -m 2 ) / m 1 ×100%, where m 1 is the content of petroleum in the initial soil (10738 mg / kg), and m 2 is the content of petroleum in the remediated soil in this example, and the result is 76.02%.

[0062] Example 5:

[0063] A method for treating oil-contaminated soil is the same as Example 1 above, except that the soil remediation agent in this example is prepared by the following method:

[0064] (1) Mix glass powder with a fineness of 150 mesh, titanium dioxide powder, and copper powder evenly according to a mass ratio of 1.8:0.55:0.4, and then heat it to 750 °C at a heating rate of 10 °C / min in a nitrogen atmosphere and hold for 20 min. The melting temperature of the glass powder is about between 670 and 700 °C. After the sintering is completed, cool it to room temperature, then crush the sintered product, and then screen out the particulate matter with a particle size distribution between 1 and 3 mm to obtain the precursor for standby.

[0065] (2) Mix the precursor with 10% hydrofluoric acid by mass according to a ratio of 1 g:12 ml, let it stand for 30 min for surface treatment, after completion, wash it with clear water to remove the residual hydrofluoric acid, and then dry it to constant weight at 100 °C to obtain the soil remediation agent.

[0066] Calculate the petroleum degradation rate of the petroleum-contaminated soil in this example. The calculation formula is (m 1 -m 2 ) / m 1 ×100%, where m 1is the content of petroleum in the initial soil (10738 mg / kg), m 2 is the content of petroleum in the repaired soil of this example, and the result is 84.14%.

[0067] Example 6:

[0068] A method for treating oil-polluted soil is the same as Example 2 above, except that the soil repair agent in this example is prepared by the following method:

[0069] (1) Mix glass powder with a fineness of 200 meshes and titanium dioxide powder in a mass ratio of 1.5:0.5, stir evenly, and then heat to 800 °C at a heating rate of 10 °C / min in a nitrogen atmosphere and hold for 20 min. The melting temperature of the glass powder is about between 750 and 780 °C. After the sintering is completed, cool to room temperature, then crush the sintered product, and then screen out the particles with a particle size distribution between 1 and 3 mm to obtain the precursor for standby.

[0070] (2) Mix the precursor with 20% hydrofluoric acid by mass in a ratio of 1 g:5 ml, let it stand for 20 min for surface treatment, after completion, wash with clear water to remove the residual hydrofluoric acid, and then dry to constant weight at 80 °C to obtain the soil repair agent.

[0071] Calculate the petroleum degradation rate of the oil-polluted soil in this example. The calculation formula is (m 1 -m 2 ) / m 1 ×100%, where m 1 is the content of petroleum in the initial soil (10738 mg / kg), m 2 is the content of petroleum in the repaired soil of this example, and the result is 65.93%.

[0072] Example 7:

[0073] A method for treating oil-polluted soil includes the following steps:

[0074] (i) Mix the oil-polluted soil (from a certain oilfield, with a petroleum content of 10738 mg / kg), the repair agent prepared in Example 3, and clear water in a ratio of 10 parts by weight: 7 parts by weight: 3.2 parts by weight, stir evenly and let it stand for 1.5 hours to obtain the pretreated soil.

[0075] (ii) Spread out the pretreated soil to form a soil layer with an average thickness of 1 cm, then irradiate it with an 800 W lamp, the light source is 40 cm away from the soil layer, continuously irradiate for 168 hours under the above light conditions, and turn over the soil every 7 hours. After completion, magnetically adsorb and separate the repair agent in the soil to obtain the repaired soil.

[0076] Calculate the oil degradation rate of the petroleum-contaminated soil in this example. The calculation formula is (m 1 -m 2 ) / m 1 ×100%, where m 1 is the content of oil in the initial soil (10738 mg / kg), and m 2 is the content of oil in the repaired soil in this example. The result is 64.71%.

[0077] Example 8:

[0078] A method for treating oil-contaminated soil is the same as Example 2 above, except that the soil conditioner in this example is prepared by the following method: Glass powder, titanium dioxide powder, copper powder, and iron powder with a fineness of 200 mesh are mixed evenly according to a mass ratio of 1.5:0.5:0.3:0.22, and then heated to 800 °C at a heating rate of 10 °C / min in a nitrogen atmosphere and held for 20 min. The melting temperature of the glass powder is about between 750 and 780 °C. After the sintering is completed, it is cooled to room temperature, and then the sintered product is crushed, and then particles with a particle size distribution between 1 and 3 mm are screened out to obtain the soil conditioner.

[0079] Calculate the oil degradation rate of the petroleum-contaminated soil in this example. The calculation formula is (m 1 -m 2 ) / m 1 ×100%, where m 1 is the content of oil in the initial soil (10738 mg / kg), and m 2 is the content of oil in the repaired soil in this example. The result is 81.26%.

[0080] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a petroleum-contaminated soil remediation agent, characterized in that: The steps include: (1) glass powder, titanium dioxide powder, copper powder and iron powder are mixed evenly and sintered in a protective atmosphere. After the mixture is cooled to room temperature, the sintered product is crushed and sieved to obtain a precursor. (2) placing the precursor in hydrofluoric acid for surface treatment, and then washing and drying to obtain the soil remediation agent; In step (1), the mass ratio of the glass powder, titanium dioxide powder, copper powder and iron powder is 1.5-2: 0.5-0.62: 0.3-0.5: 0.22-0.35; In step (1), the sintering temperature is not higher than 800° C. and not lower than the melting temperature of the glass powder; the sintering time is 20 to 30 minutes; In step (2), the ratio of the precursor to hydrofluoric acid is 1 g: 5-15 ml.

2. The method for preparing the petroleum-contaminated soil remediation agent according to claim 1, characterized in that: In step (1), the fineness of each powder is 80-200 mesh.

3. The method for preparing the petroleum-contaminated soil remediation agent according to claim 1, characterized in that: In step (1), the glass powder is made of waste glass.

4. The method for preparing the petroleum-contaminated soil remediation agent according to claim 1, characterized in that: In step (1), the protective atmosphere includes at least one of nitrogen and argon.

5. The method for preparing the petroleum-contaminated soil remediation agent according to claim 1, characterized in that: In step (1), the melting temperature of the glass powder is 500-780°C.

6. The method for preparing the petroleum-contaminated soil remediation agent according to claim 1, characterized in that: In step (1), the particle size of the precursor is 1-3 mm.

7. The method for preparing the petroleum-contaminated soil remediation agent according to claim 1, characterized in that: In step (2), the mass fraction of the hydrofluoric acid is 10-20%.

8. The method for preparing the petroleum-contaminated soil remediation agent according to any one of claims 1 to 4, characterized in that: In step (2), the surface treatment time is 20 to 40 minutes.

9. The method for preparing the petroleum-contaminated soil remediation agent according to claim 1, characterized in that: In step (2), the soil remediation agent is obtained by washing with clean water and then drying to a constant weight.

10. Use of the soil remediation agent obtained by the preparation method according to any one of claims 1 to 7 in the treatment of petroleum-contaminated soil.

11. The use according to claim 10, characterized in that: The method of the application comprises the following steps: (i) placing the petroleum-contaminated soil, the soil remediation agent and water in a reaction container, stirring them evenly and then sealing the container for heating and heat preservation to obtain pretreated soil; (ii) spreading the pretreated soil and subjecting it to light treatment, and then separating the repair agent by magnetic adsorption to obtain repaired soil.

12. The use according to claim 11, characterized in that: In step (i), the ratio of the soil, the soil remediation agent and water is 10 parts by weight: 4-7 parts by weight: 2-3.2 parts by weight.

13. The use according to claim 11, characterized in that: In step (i), the heating temperature is 180-240° C., and the insulation time is 1.5-3 hours.

14. The use according to claim 11, characterized in that: In step (i), the pressure in the reaction vessel is maintained at 0.2-0.5 MPa.

15. The use according to claim 11, characterized in that: In step (ii), the thickness of the spread pretreated soil is no more than 2 cm.

16. The use according to any one of claims 11 to 15, characterized in that: In step (ii), the light treatment time is not less than 5 days.

17. The use according to any one of claims 11 to 15, characterized in that: In step (ii), the illumination includes at least one of sunlight and artificial illumination.

18. The use according to claim 17, characterized in that In step (ii), the light source power of the artificial lighting is not less than 500W.

19. The use according to any one of claims 11 to 15, characterized in that: In step (ii), the soil is turned over every 5 to 7 hours.

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