Sophorolipid modified activated biochar and its preparation method and application

Abstract

The present invention discloses a sophorolipid-modified activated biochar, its preparation method and application. The sophorolipid-modified activated biochar includes: mixing an activator and biochar to obtain a first mixture, mixing the first mixture and water, and ultrasonically treating until uniform to obtain a first mixed solution, allowing the first mixed solution to stand for 6 to 12 h, drying to obtain a black solid, subjecting the black solid to oxygen-limited pyrolysis at 700 to 900 °C for 2 to 3 h, cooling to room temperature, sieving, washing until neutral, and drying to obtain activated biochar. Mixing the activated biochar and a sophorolipid solution, stirring until uniform, filtering, drying, cooling to room temperature, washing until neutral, and drying to obtain the sophorolipid-modified activated biochar. The addition of the sophorolipid-modified activated biochar can significantly improve the physical and chemical properties of contaminated soil, provide nutrients for plants and increase the bioavailability of petroleum hydrocarbons in the soil, and can significantly improve the degradation rate of petroleum hydrocarbons in petroleum-contaminated soil by Iris lactea Pall. var. chinensis (Fisch.) Koidz., and improve the efficiency of phytoremediation of petroleum-contaminated soil by Iris lactea Pall. var. chinensis (Fisch.) Koidz.

Description

Technical Field

[0001] The present invention belongs to the technical field of contaminated soil remediation, and specifically relates to a sophorolipid-modified activated biochar and a preparation method and application thereof. Background Art

[0002] As a substance rich in organic carbon, the application of biochar can not only significantly improve soil pH, CEC, DOC and soil enzyme activity, but also promote microbial activity and plant root growth. Biochar is also a good immobilization carrier. Due to its many pores, large specific surface area, and surface functional groups, it can adsorb petroleum pollutants in soil contaminated by petroleum hydrocarbons, and provide a good living environment for microorganisms, which can significantly enhance the remediation effect of petroleum-contaminated soil.

[0003] Phytoremediation is a purification process mediated by plants. Contaminated soil can be remediated through plant extraction, plant volatilization, plant stabilization, plant accumulation and rhizosphere degradation, while minimizing the generation of secondary waste. Iris lacteal Pall is an effective plant for remediating petroleum hydrocarbon pollution. It has a well-developed root system and many rhizosphere microorganisms. It has strong tolerance and certain degradation ability for both low and high concentrations of petroleum hydrocarbon pollutants in the soil. It is an ideal plant for remediating petroleum-contaminated soil. However, some high-molecular-weight polycyclic aromatic hydrocarbons in the soil, such as benzopyrene, have low bioavailability in the soil, which limits the effect of phytoremediation. Studies have shown that the addition of surfactants is beneficial to the dissolution and elution of organic pollutants such as petroleum hydrocarbons in the soil, and on the other hand, it helps to improve the bioavailability of petroleum hydrocarbons in the soil, thereby improving the effect of phytoremediation of petroleum-contaminated soil. The article "Uptake of Hydrocarbon by Pseudomonas fluorescens (P1) and Pseudomonas putida (K1) Strains in the Presence of Surfactants: A Cell Surface Modification" in "Water, Air, & Soil Pollution" reports that conventional chemical surfactants (for example: non-ionic chemical surfactants such as Triton X-100 and Tween-80) have shortcomings such as high energy consumption in the preparation process and easy secondary pollution, which limits the production and wide application of surfactants. Summary of the invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a sophorolipid-modified activated biochar. Compared with chemical surfactants such as Triton X-100, the sophorolipid-modified activated biochar loads sophorolipids as a biosurfactant on the biochar, which can effectively increase the contact area between microorganisms and petroleum hydrocarbons and improve the degradation efficiency of petroleum hydrocarbons.

[0005] Another object of the present invention is to provide a preparation method of the above-mentioned sophorolipid-modified activated biochar.

[0006] Another object of the present invention is to provide the application of the above-mentioned sophorolipid-modified activated biochar in strengthening the remediation of petroleum-polluted soil by the ornamental plant Iris lactea Pall. Using the sophorolipid-modified activated biochar to improve the soil environment, provide nutrients and increase the bioavailability of petroleum hydrocarbons in the soil, solve the problems of low bioavailability and low biological efficiency of organic pollutants in the soil, strengthen the transfer of organic pollutants into plants while promoting the growth and development of Iris lactea Pall., and add the sophorolipid-modified activated biochar to the petroleum-polluted soil, so as to achieve the purpose of strengthening the phytoremediation of petroleum-polluted soil.

[0007] The object of the present invention is achieved by the following technical solutions.

[0008] A preparation method of a sophorolipid-modified activated biochar, comprising the following steps:

[0009] Step 1, mixing an activator and biochar to obtain a first mixture, mixing the first mixture and water, and ultrasonicating until uniform to obtain a first mixed solution, allowing the first mixed solution to stand for 6 - 12 h, drying to obtain a black solid, subjecting the black solid to oxygen-limited pyrolysis at 700 - 900 °C for 2 - 3 h, cooling to room temperature, sieving, washing until neutral, and drying to obtain activated biochar, wherein, by mass parts, the ratio of the biochar to the activator is (1 - 3):1;

[0010] In step 1, the activator is one or a mixture of several of KOH, K2CO3, and ZnCl2.

[0011] In step 1, the ultrasonicating time is 0.5 - 1.5 h.

[0012] In step 1, the ratio of the mass parts of the first mixture to the volume parts of water in step 1 is 1:(20 - 30), the unit of mass parts is g, and the unit of volume parts is mL.

[0013] In step 1, the drying temperature is 60 - 120 °C, and the drying time is 12 - 18 h.

[0014] In step 1, the drying temperature is 70 - 90 °C, and the drying time is 12 - 18 h.

[0015] Step 2: Mix the activated biochar and the sophorolipid solution, stir until homogeneous, filter, dry, cool to room temperature, wash until neutral, and then dry to obtain sophorolipid-modified activated biochar, wherein the ratio of the mass fraction of the activated biochar to the molar fraction of sophorolipid in the sophorolipid solution is 1:(5 - 15), the unit of the mass fraction is g, and the unit of the molar fraction is mmol.

[0016] In Step 2, the sophorolipid solution is a mixture of water and sophorolipid, and the concentration of sophorolipid in the sophorolipid solution is 5 - 15 mmol / L.

[0017] In Step 2, the sophorolipid solution is obtained by mixing sophorolipid and water and dispersing them evenly by ultrasonic treatment for 1 - 3 h.

[0018] In Step 2, the stirring time is 24 - 48 h, preferably 24 - 36 h, and the stirring temperature is room temperature.

[0019] In Step 2, the stirring speed is 180 - 230 rpm, preferably 180 - 200 rpm.

[0020] In Step 2, the drying temperature is 60 - 120 °C, and the drying time is 12 - 18 h.

[0021] In Step 1 and Step 2, the drying temperature is preferably 80 - 105 °C.

[0022] In the above technical solution, the method for obtaining the biochar is as follows: Dry the powdered biochar raw material, sieve it, then carry out oxygen-limited pyrolysis at 300 - 700 °C for 2 - 3 h, sieve it again, wash it until neutral, and then dry it to obtain biochar.

[0023] In the above technical solution, the pH of the neutrality is 6.5 - 7.5.

[0024] In the above technical solution, the biochar raw material is carbon-rich biomass. For example, the carbon-rich biomass is corn straw or wheat straw.

[0025] The sophorolipid-modified activated biochar obtained by the above preparation method.

[0026] The application of the above sophorolipid-modified activated biochar in enhancing the remediation of petroleum-polluted soil by Iris lactea Pall.

[0027] In the above technical solution, the method for enhancing the remediation of petroleum-polluted soil by Iris lactea Pall. with sophorolipid-modified activated biochar includes the following steps:

[0028] S1: Add sophorolipid-modified activated biochar to the petroleum-polluted soil;

[0029] In S1, by mass parts, the sophorolipid-modified activated biochar is 2-3 wt% of the petroleum-contaminated soil.

[0030] S2. Transplant the Iris lactea Pall. var. chinensis (Fisch.) Koidz. plants into the petroleum-contaminated soil added with sophorolipid-modified activated biochar for cultivation, and water to keep the water content of the petroleum-contaminated soil added with sophorolipid-modified activated biochar at 30-60 VOL% of the field water holding capacity.

[0031] In S2, water to keep the water content of the petroleum-contaminated soil added with sophorolipid-modified activated biochar at 45-55 VOL% of the field water holding capacity.

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

[0033] 1. The present invention adds sophorolipid-modified activated biochar to the petroleum-contaminated soil and transplants Iris lactea Pall. var. chinensis (Fisch.) Koidz. into the petroleum-contaminated soil added with sophorolipid-modified activated biochar for combined remediation of the petroleum-contaminated soil. The addition of sophorolipid-modified activated biochar can significantly improve the physical and chemical properties of the petroleum-contaminated soil, provide nutrients for plants and increase the bioavailability of petroleum hydrocarbons in the soil, thereby promoting the growth and development of plants, enhancing the tolerance of plants to organic pollutants, and significantly improving the degradation rate of petroleum hydrocarbons in the petroleum-contaminated soil by Iris lactea Pall. var. chinensis (Fisch.) Koidz., and improving the efficiency of phytoremediation of the petroleum-contaminated soil by Iris lactea Pall. var. chinensis (Fisch.) Koidz.

[0034] 2. The preparation method of the present invention has low cost, wide application range, does not cause secondary pollution, helps to improve the soil structure and beautify the environment. Brief Description of the Drawings

[0035] Figure 1(a) is a scanning electron microscope image (SEM) of the biochar prepared in Example 1.

[0036] Figure 1(b) is a scanning electron microscope image (SEM) of the activated biochar prepared in Example 2.

[0037] Figure 1(c) is a scanning electron microscope image (SEM) of the sophorolipid-modified activated biochar prepared in Example 3.

[0038] Figure 2 is the Fourier transform infrared spectroscopy scan (FTIR) of the biochar prepared in Example 1, the activated biochar prepared in Example 2, and the sophorolipid-modified activated biochar prepared in Example 3.

[0039] Figure 3 is the pore size distribution diagram of the biochar prepared in Example 1, the activated biochar prepared in Example 2, and the sophorolipid-modified activated biochar prepared in Example 3.

[0040] Figure 4Trend chart of total petroleum hydrocarbon content in soil after 90 days of degradation in Examples 4 to 6 and Comparative Example 1;

[0041] Figure 5 Trend chart of the degradation rate of total petroleum hydrocarbons in soil after 90 days of degradation in Examples 4 to 6 and Comparative Example 1. Detailed implementation manners

[0042] The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

[0043] The manufacturers and purities of the drugs involved in the following examples and tests are as follows:

[0044]

[0045] The name brands and other information of the test characterization instruments used in the following examples are as follows:

[0046]

[0047]

[0048] In the following examples, the biochar raw material is corn straw (agricultural waste), and the corn straw is taken from Lianyungang City, Jiangsu Province.

[0049] The calculation formula for the degradation rate of total petroleum hydrocarbons in the following examples is:

[0050] Wherein,

[0051] X = 10, 30, 60 and 90.

[0052] In the following examples, the water is deionized water.

[0053] In the following examples, the field water holding capacity refers to the highest soil water content that the soil can stably maintain.

[0054] Test method for the concentration of total petroleum hydrocarbons: According to the national environmental protection standard of the People's Republic of China (HJ 1021-2019) for the published petroleum hydrocarbons (C 10 -C 40)Determination standard: The concentration of total petroleum hydrocarbons was determined by gas chromatography (GC). The determination was carried out using an Agilent 7890 gas chromatograph (Agilent, CA, USA). The operating parameters were as follows: The carrier gas was high-purity nitrogen, 1.1 mL / min; air flow rate: 300 ml / min; hydrogen flow rate: 40 ml / min; tail gas blow flow rate: 30 ml / min; chromatographic column: HP-5 (30 m × 0.32 mm, 0.25 μm); splitless mode; injection volume: 1 μl; injection port temperature was 300 °C, detector temperature 325 °C. Temperature programming: The initial temperature was maintained at 45 °C for 3 min, then heated at 15 °C / min to 210 °C and maintained for 0 min, and finally heated at 30 °C / min to 300 °C and maintained for 8 min.

[0055] Example 1

[0056] A preparation method of biochar, comprising: repeatedly washing the biochar raw material with deionized water to remove surface dust, crushing the biochar raw material into powder and drying it in an oven at 60 °C for 12 h, passing the dried powdered biochar raw material through a 200-mesh sieve, placing it in a ceramic crucible (filled), removing the air with N2 and immediately covering the lid of the ceramic crucible, sealing the ceramic crucible and the lid with tin foil, pyrolyzing in a muffle furnace at 700 °C for 3 h, passing through a 50-mesh sieve, and then repeatedly washing with deionized water for multiple times until the pH is 7.2, and drying in an oven at 80 °C for 12 h to obtain biochar (700BC).

[0057] Example 2

[0058] A preparation method of activated biochar, comprising: mixing an activator and the biochar prepared in Example 1 to obtain a first mixture, mixing the first mixture and water, and ultrasonicating for 1 h until evenly dispersed to obtain a first mixed solution, allowing the first mixed solution to stand for 9 h, drying at 80 °C for 12 h to obtain a black solid, placing the black solid in a tubular furnace and heating it at a heating rate of 10 °C / min to 800 °C and performing oxygen-limited pyrolysis at 800 °C for 2 h (maintaining a nitrogen environment), naturally cooling to 20 - 25 °C and then opening the furnace to take out (during the oxygen-limited pyrolysis process, nitrogen was uniformly introduced into the tubular furnace at a speed of 0.5 L / min until the temperature in the tubular furnace decreased to 20 - 25 °C and the introduction stopped), passing through a 50-mesh sieve, washing with a 1 mol / L HCl aqueous solution and then repeatedly washing with deionized water for multiple times until the pH is 7.2, and drying in an oven at 80 °C for 12 h to obtain activated biochar (700KBC), wherein, by mass fraction, the ratio of biochar to activator is 1:1, the ratio of the mass fraction of the first mixture to the volume fraction of water is 1:25, the unit of mass fraction is g, the unit of volume fraction is mL, and the activator is KOH (solid powder).

[0059] Example 3

[0060] A preparation method of sophorolipid-modified activated biochar, comprising the following steps:

[0061] Step 1: Obtain activated biochar. The steps for obtaining activated biochar are the same as those for preparing activated biochar in Example 2.

[0062] Step 2: Mix the activated biochar and sophorolipid solution in a beaker, and stir evenly at a speed of 180 rpm for 24 h at room temperature using a magnetic stirrer. Perform solid-liquid separation (filtration) using a vacuum filtration device, dry in a constant-temperature drying oven at 80 °C for 12 h, cool to room temperature, wash with deionized water multiple times until the pH is 7.2, and dry at 80 °C for 12 h until constant weight to obtain sophorolipid-modified activated biochar (700KBC-SLs), which is stored in a sample bottle for later use. Among them, the ratio of the mass fraction of the activated biochar to the molar fraction of sophorolipid in the sophorolipid solution is 1:10, the unit of the mass fraction is g, the unit of the molar fraction is mmol, the sophorolipid solution is a mixture of water and sophorolipid, the concentration of sophorolipid in the sophorolipid solution is 10 mmol / L, and the sophorolipid solution is obtained by mixing 10 mmol of sophorolipid and water in a 1-L volumetric flask and ultrasonically dispersing evenly for 2 h.

[0063] Perform SEM analysis on the biochar (700BC) prepared in Example 1, the activated biochar (700KBC) prepared in Example 2, and the sophorolipid-modified activated biochar (700KBC-SLs) prepared in Example 3. Comparing Figure 1(a), Figure 1(b), and Figure 1(c), it can be seen that the surface of the sophorolipid-modified activated biochar (700KBC-SLs) prepared in Example 3 is rougher than that of Example 1 and Example 2, and some scale-like structures appear on the surface. This may be because after modification with sophorolipid (SLs), SLs are loaded on the biochar surface. In addition, there are blockages of flocculent structures in the surface pores of the sophorolipid-modified activated biochar (700KBC-SLs) prepared in Example 3. This may be because the loading of SLs blocks some pores of the biochar. These results indicate that SLs have been successfully loaded onto the biochar.

[0064] As Figure 2 shown, perform FTIR analysis on the biochar (700BC) prepared in Example 1, the activated biochar (700KBC) prepared in Example 2, and the sophorolipid-modified activated biochar (700KBC-SLs) prepared in Example 3. It is found that the peak area of the O-containing functional group (C-O(1080 cm -1 )) in Example 2 is smaller than that in Example 1. This is because KOH will consume some oxygen-containing functional groups during pyrolysis. Compared with Example 1, the C=C peak (1569 cm -1)、The intensity of the C-H peak (792 cm -1 ) increases, indicating that during the activation process, KOH reacts with the C structure and functional groups such as hydroxyl groups on the surface of biochar, changing the number of functional groups on the biochar surface and causing changes in the absorption peaks in the infrared spectrum. However, the pore-forming treatment with KOH does not change the types of functional groups of biochar, indicating that the functional groups of biochar exist in the main structure. Compared with Example 1 and Example 2, the peak intensity of most peaks in Example 3 increases significantly, especially the C-O (1080 cm -1 ) group, which may be related to the increase in oxygen-containing functional groups on the biochar surface after modification with SLs. Since the content of C-O-C in SLs is relatively high, the absorption peak of Example 3 at this position is stronger than that of Example 1 and Example 2, indicating that sophorolipids have been successfully bound to the biochar.

[0065] Information such as the total specific surface area, pore volume, and pore diameter of 700BC prepared in Example 1, 700KBC prepared in Example 2, and 700KBC-SLs prepared in Example 3 is shown in Table 1.

[0066] Table 1

[0067]

[0068] As shown in Table 1 and Figure 3 , after activation with KOH, the pore volume and specific surface area of biochar increase to a large extent. KOH has a significant effect on improving the pore structure of biochar, increasing the specific surface area of biochar from 155.255 m 2 / g to 515.947 m 2 / g and the total pore volume from 0.104 cm 3 / g to 0.530 cm 3 / g. This is because of the strong corrosiveness of KOH to biochar, which corrodes the fragments between pores and the pore walls, connecting small pores to form large pores, resulting in a porous structure of biochar and promoting the development of the pore structure of biochar, providing a large number of active sites for the loading of surfactants.

[0069] Examples 4 - 6

[0070] Determine the total petroleum hydrocarbon content in the soil:

[0071] Collect clean soil around the Tianjin Dagang Oilfield, and collect soil from the top 10.0 cm of the soil surface. Air-dry the collected soil at room temperature and sieve it through a 2-mm sieve to obtain clean soil. Mix the clean soil with petroleum to make the total petroleum hydrocarbon concentration in the soil reach 40 g / kg, and then water and balance it for two weeks at room temperature (the water in the soil will continuously evaporate into the air and be lost, and after two weeks of balancing, the water in the soil reaches equilibrium with the water in the air), and then obtain petroleum-contaminated soil. Apply the biochar material to the remediation of petroleum-contaminated soil, and the specific method includes the following steps:

[0072] S1. Add the biochar material to the petroleum-contaminated soil and mix well. By mass fraction, the biochar material is 2 wt% of the petroleum-contaminated soil. The biochar material is one of 700BC (biochar obtained from the preparation of Example 1), 700KBC (activated biochar obtained from the preparation of Example 2), and 700KBC-SLs (sophorolipid-modified activated biochar obtained from the preparation of Example 3). Example 4 uses 700BC as the biochar material, Example 5 uses 700KBC as the biochar material, and Example 6 uses 700KBC-SLs as the biochar material;

[0073] S2. Add the petroleum-contaminated soil added with the biochar material to a flowerpot made of polypropylene at a rate of 1.5 kg per pot. Use the method of dividing plants for seedling raising, and transplant Iris lacteal Pall into the flowerpot made of polypropylene at a rate of 3 plants per pot. Place the flowerpot on a light culture rack, and control the light cycle of Iris lacteal Pall to be 16 hours of sunlight and 8 hours of darkness through the power switch, and keep the temperature at 25 ± 2 °C. Water to keep the water content of the petroleum-contaminated soil added with the biochar material at 50 VOL% of the field water holding capacity (water once a day at a fixed time), and use the weighing method to maintain this water content.

[0074] On the 0th, 10th, 30th, 60th, and 90th days after planting, soil around the rhizosphere of Iris lactea Pall. was collected to determine the total petroleum hydrocarbon content in the soil: Weigh 5.0 g of the soil around the rhizosphere of Iris lactea Pall. (The method for obtaining 5.0 g of the soil around the rhizosphere of Iris lactea Pall. is as follows: Sampling is carried out at three soil depths (0 - 5 cm, 5 - 10 cm, and 10 - 15 cm) and mixed evenly), wrap the soil with filter paper and fix it with staples. Place the wrapped soil sample in a glass Soxhlet extraction tube, add 75 mL of n - hexane and 75 mL of dichloromethane for extraction, connect the glass Soxhlet extraction tube to a round - bottom flask for assembly, and extract in a fat extractor at 65 °C for 12 h. After the extraction is completed, wait for the extract to cool, and concentrate the n - hexane and dichloromethane to dryness at 40 °C using a rotary evaporator. Then, re - volume to 10 mL with n - hexane to determine the concentration of total petroleum hydrocarbons. Method for determining the total petroleum hydrocarbon content in the soil: Multiply the concentration of total petroleum hydrocarbons by 10 mL, and then divide by the mass of the soil (5 g) to obtain the total petroleum hydrocarbon content in the soil.

[0075] Example Biochar material used Example 4 Example 1 Example 5 Example 2 Example 6 Example 3

[0076] Comparative Example 1

[0077] The method for determining the total petroleum hydrocarbon content in the soil is basically the same as that in Examples 4 - 6 for "determining the total petroleum hydrocarbon content in the soil", and the only difference is that no biochar material is added in this comparative example.

[0078] In Examples 4 - 6 and Comparative Example 1, the total petroleum hydrocarbon content in the soil was measured on the 0th, 10th, 30th, 60th, and 90th days after planting, as shown in Table 2.

[0079] Table 2

[0080]

[0081] Total petroleum hydrocarbon content in the soil = Total petroleum hydrocarbon mass in the soil / Soil mass.

[0082] The specific degradation rates of total petroleum hydrocarbons in Examples 4 - 6 and Comparative Example 1 are shown in Table 3.

[0083] Table 3

[0084]

[0085] Both the plant (Iris lactea Pall.) and the biochar material have a certain remediation effect on petroleum - contaminated soil. As shown in Table 2, Table 3, Figure 4 and Figure 5 shown ( Figure 4 and Figure 5The comparative example represents Comparative Example 1). After the 90-day pot experiment, the total petroleum hydrocarbon content and degradation rate in Examples 4 to 6 and Comparative Example 1 changed significantly. After the 90-day pot experiment, the total petroleum hydrocarbon content in the soil of Example 4 decreased by 29.0%, the total petroleum hydrocarbon content in the soil of Example 5 decreased by 34.1%, and the total petroleum hydrocarbon content in the soil of Example 6 decreased by 39.6%, all higher than 20.5% of Comparative Example 1. Compared with Example 1, the activated biochar of Example 2 was activated by KOH, which enriched the pore structure of the biochar and effectively improved the adsorption performance of the biochar for petroleum hydrocarbons. At the same time, due to the enrichment of the pore structure, a more suitable growth and living environment was provided for the microorganisms in the soil, further promoting the dissolution of petroleum hydrocarbons in the soil.

[0086] The total specific surface area is one of the important indicators of the adsorption material. The larger its value, the more sufficient the reaction to provide active sites. It can be seen from Table 1 that although the total specific surface area of the sophorolipid-modified activated biochar prepared in Example 3 is smaller than that of the activated biochar prepared in Example 2, by adding the sophorolipid-modified activated biochar of Example 3 as a surfactant, the sophorolipid-modified activated biochar increases the number of oxygen-containing functional groups on the biochar surface. The oxygen-containing functional groups act on the soluble petroleum hydrocarbons in the soil, improving the bioavailability of petroleum hydrocarbons, and thus promoting the degradation of petroleum hydrocarbons by microorganisms. Compared with Example 4 and Example 5, the total petroleum hydrocarbon content in the soil of Example 6 decreased more, because the surfactant can promote the dissolution of petroleum hydrocarbons in the soil, and thus promote the degradation of petroleum hydrocarbons. The soluble petroleum hydrocarbons can be extracted by plants or degraded by microorganisms, resulting in a decrease in the total petroleum hydrocarbon content in the soil.

[0087] When Iris lactea Pall. is applied to the remediation of petroleum-polluted soil, compared with other remediation plants, Iris lactea Pall. has the advantages of developed roots, many rhizosphere microorganisms, strong tolerance and certain degradation ability to petroleum hydrocarbon pollutants with both low and high contents in the soil. It is an ideal plant based on the green in-situ remediation technology, which helps to improve soil degradation and productivity decline caused by petroleum pollution, and restore and increase biodiversity.

[0088] The above makes an exemplary description of the present invention. It should be noted that without departing from the core of the present invention, any simple deformation, modification or equivalent replacement that can be made by those skilled in the art without creative labor falls within the protection scope of the present invention.

Claims

1. Application of sophorolipid-modified activated biochar in enhancing Iris lactea Pall. var. chinensis (Fisch.) Koidz. to repair petroleum-polluted soil, characterized in that The preparation method of sophorolipid-modified activated biochar comprises the following steps: Step 1: Mix an activator and biochar to obtain a first mixture. Mix the first mixture and water, and ultrasonicate until uniform to obtain a first mixed solution. Let the first mixed solution stand for 6 - 12 h, dry it to obtain a black solid. Subject the black solid to oxygen-limited pyrolysis at 700 - 900 °C for 2 - 3 h, cool it to room temperature, screen it, wash it until neutral, and dry it to obtain activated biochar. Among them, by mass fraction, the ratio of the biochar to the activator is (1 - 3):1, and the activator is KOH. The method for obtaining the biochar is as follows: Dry the powdered biochar raw material, screen it, then subject it to oxygen-limited pyrolysis at 300 - 700 °C for 2 - 3 h, screen it, wash it until neutral, and dry it to obtain biochar. The biochar raw material is corn straw; Step 2: Mix the activated biochar and a sophorolipid solution, stir until uniform, filter, dry, cool to room temperature, wash until neutral, and dry to obtain sophorolipid-modified activated biochar. Among them, the ratio of the mass fraction of the activated biochar to the molar fraction of sophorolipid in the sophorolipid solution is 1:(5 - 15), the unit of mass fraction is g, and the unit of molar fraction is mmol; The method for sophorolipid-modified activated biochar to enhance the remediation of petroleum-polluted soil by Iris lactea Pall. var. chinensis (Fisch.) Koidz. comprises the following steps: S1: Add sophorolipid-modified activated biochar to the petroleum-polluted soil. By mass fraction, the sophorolipid-modified activated biochar is 2 - 3 wt% of the petroleum-polluted soil; S2: Transplant Iris lactea Pall. var. chinensis (Fisch.) Koidz. plants into the petroleum-polluted soil added with sophorolipid-modified activated biochar for cultivation, and water to keep the water content of the petroleum-polluted soil added with sophorolipid-modified activated biochar at 30 - 60 VOL% of the field water holding capacity.

2. The application according to claim 1, characterized in that, In Step 1, the ratio of the mass fraction of the first mixture to the volume fraction of water in Step 1 is 1:(20 - 30), the unit of mass fraction is g, and the unit of volume fraction is mL.

3. The application according to claim 1, wherein In Step 2, the sophorolipid solution is a mixture of water and sophorolipid, and the concentration of sophorolipid in the sophorolipid solution is 5 - 15 mmol / L.

4. The application according to claim 1, characterized in that, In Step 1, the ultrasonication time is 0.5 - 1.5 h.

5. The application according to claim 1, wherein In Step 2, the stirring time is 24 - 48 h, and the stirring temperature is room temperature.

6. The application according to claim 1, characterized in that, The concentration of petroleum hydrocarbons in the petroleum-polluted soil is 40 g / kg.

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