Preparation method and application of beta-cyclodextrin modified straw

Abstract

This invention relates to the field of petroleum-contaminated soil remediation technology, specifically a method for preparing β-cyclodextrin-modified straw and its application. The invention involves pretreating corn straw with alkali, then using propylene oxide as a crosslinking agent to chemically graft and covalently bond β-cyclodextrin onto the straw surface, resulting in β-cyclodextrin-modified straw. The modified straw is then sterilized and co-cultured with a degradation-promoting bacterial system composed of *Trichoderma seabuckthorne* and *Pseudomonas aeruginosa* to obtain a modified straw-degrading bacterial system consortium. This invention organically combines the inclusion-solubilizing effect of β-cyclodextrin, the microbial colonization carrier effect of straw, and its nutrient regulation effect, significantly improving the biodegradation efficiency of petroleum hydrocarbons. Experiments show that the adsorption capacity of the modified straw for petroleum hydrocarbons increased from 0.34 mg / g to 2.06 mg / g, the bacterial biomass increased by 2.42 times, the petroleum hydrocarbon degradation rate increased from 76.9% to 94.6%, and the half-life was shortened from 4.63 days to 2.54 days. This invention is low-cost, environmentally friendly, and suitable for in-situ bioremediation of petroleum-contaminated soil.

Description

Technical Field

[0001] This invention relates to the field of petroleum-contaminated soil remediation technology, specifically a method for preparing β-cyclodextrin-modified straw and its application. Background Technology

[0002] Petroleum-contaminated soil refers to soil contaminated by petroleum hydrocarbons that enter the soil and exceed its self-purification capacity during the extraction, transportation, storage, processing, and use of petroleum, due to leaks, oil sludge accumulation, or improper disposal of oily waste. Petroleum pollutants typically consist of alkanes, cycloalkanes, aromatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), resins, and asphaltenes, characterized by complex composition, strong hydrophobicity, and complex migration and transformation processes. Once in the soil, these pollutants not only damage soil structure and reduce aeration and permeability but also affect soil microbial communities and crop growth. Hydrophobic components, especially PAHs, are easily adsorbed by soil organic matter and mineral particles, gradually transforming into forms that are difficult to desorb and utilize during aging, thus increasing the difficulty of remediation.

[0003] Currently, methods for remediating petroleum-contaminated soil mainly include physical remediation, chemical remediation, and bioremediation. Among these, bioremediation has become an important technological direction for the treatment of petroleum-contaminated soil due to its advantages such as lower cost, less environmental disturbance, and applicability to in-situ remediation. Microbial remediation mainly relies on indigenous microorganisms or exogenous functional microbial agents to oxidize, crack, and mineralize petroleum hydrocarbons. However, in actual soil environments, exogenous microbial agents are often affected by factors such as pollutant toxicity, soil porosity limitations, competition from indigenous microorganisms, environmental stress, and insufficient nutrients, resulting in problems such as weak colonization capacity, rapid activity decay, and insufficient sustainability of remediation effects.

[0004] Furthermore, while petroleum hydrocarbon pollutants can provide carbon sources for microorganisms, they typically lack essential nutrients such as nitrogen and phosphorus, which are necessary for microbial growth and metabolism. This can easily lead to an imbalance in the soil's carbon-nitrogen-phosphorus ratio, limiting the growth and reproduction of degrading bacteria and the synthesis of related degrading enzymes. Simultaneously, petroleum hydrocarbons, especially polycyclic aromatic hydrocarbons (PAHs), are highly hydrophobic, easily adsorbing and aging in the soil, making it difficult for microorganisms to effectively contact and utilize these pollutants. Therefore, insufficient persistence of microbial agents, nutrient limitations, and low bioavailability of pollutants are the main factors restricting the efficiency of bioremediation of petroleum-contaminated soils.

[0005] To address the aforementioned issues, existing technologies have employed methods such as nutrient regulation, surfactant solubilization, cyclodextrin-assisted desorption, and biochar or straw-based immobilization of microbial agents to enhance the remediation of petroleum-contaminated soils. However, these technologies still have certain limitations: simply adding nutrients can easily lead to excessively rapid nutrient release and uneven distribution; surfactants and free cyclodextrins have limited retention time in the soil, making it difficult to simultaneously provide a colonization carrier for microbial agents; and biochar or ordinary straw materials have limited capabilities in the directional inclusion, interfacial mass transfer, and availability regulation of hydrophobic petroleum hydrocarbons.

[0006] Therefore, how to organically combine the inclusion and solubilizing effect of β-cyclodextrin on hydrophobic petroleum hydrocarbons, the microbial colonization carrier effect of straw-based biomass materials, and the nutrient regulation effect in the bioremediation process to construct a low-cost, environmentally friendly, and sustainable composite remediation material that promotes the degradation of petroleum hydrocarbons is a technical problem that urgently needs to be solved in the field of bioremediation of petroleum-contaminated soil. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing β-cyclodextrin-modified straw and its application, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing β-cyclodextrin-modified straw, comprising the following steps:

[0010] S1. After crushing the corn stalks, add them to an alkaline solution for alkaline modification treatment, filter, wash, and dry to obtain alkaline modified stalks.

[0011] S2. Add the alkali-modified straw obtained in step S1 to a buffer solution, add β-cyclodextrin and a crosslinking agent to carry out a grafting modification reaction. After the reaction is completed, wash and dry to obtain β-cyclodextrin-modified straw.

[0012] As a further aspect of the present invention: the alkaline solution in step S1 is a 0.5M NaOH solution, the material-to-liquid ratio for alkali modification treatment is 1:30 g / mL, the treatment temperature is 50℃, and the treatment time is 12h.

[0013] As a further aspect of the present invention: the buffer solution in step S2 is a 2-morpholine ethanesulfonic acid buffer solution with pH=5.5, the concentration of β-cyclodextrin is 0.15 mmol / L, the crosslinking agent is propylene oxide, and the molar ratio of β-cyclodextrin to propylene oxide is 1:3.

[0014] As a further aspect of the present invention: the grafting modification reaction in step S2 is carried out at room temperature for 6 hours.

[0015] Secondly, the present invention provides a β-cyclodextrin-modified straw-degrading bacterial system complex, comprising β-cyclodextrin-modified straw prepared by any of the above-described methods and a degrading bacterial system loaded thereon, wherein the degrading bacterial system is a combination of Trichoderma seabuckthorne and Pseudomonas aeruginosa.

[0016] As a further aspect of the present invention: the combination is prepared by the following method: the β-cyclodextrin modified straw prepared by the above preparation method is sterilized, then soaked in a proliferation medium, and the degradation strain is inoculated at an inoculation rate of 10% m:v, and cultured at 30°C for 72 hours.

[0017] As a further aspect of the present invention: the proliferation medium is a mixed medium of PDB and LB, with a liquid-to-solid ratio of 10.0 mL: 1.0 g.

[0018] Thirdly, the present invention provides a bioremediation method for petroleum-contaminated soil, wherein the above-mentioned β-cyclodextrin-modified straw-degrading microbial complex is applied to petroleum-contaminated soil for bioremediation.

[0019] As a further aspect of the present invention, the amount of the β-cyclodextrin-modified straw-degrading microbial complex applied is 10% of the mass of the petroleum-contaminated soil.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] (1) This invention is the first to covalently bond β-cyclodextrin to the surface of straw through chemical grafting, organically combining the inclusion and solubilizing effect of β-cyclodextrin on hydrophobic petroleum hydrocarbons, the microbial colonization carrier effect of straw and the nutrient regulation effect, and constructing a low-cost, environmentally friendly and sustainable composite remediation material that promotes the biodegradation of petroleum hydrocarbons.

[0022] (2) The β-cyclodextrin-modified straw prepared in this invention increases the adsorption capacity of ordinary corn straw for petroleum hydrocarbons from 0.34 mg / g to 2.06 mg / g, and as a colonization carrier, it can increase the biomass of the associated bacterial strains by 2.42 times.

[0023] (3) After the microbial strain was combined with β-cyclodextrin to modify straw, compared with the microbial strain alone, the degradation rate of petroleum hydrocarbons increased from 76.9% to 94.6%, an increase of 17.7%, and the rate constant increased from 0.1497 d. -1 Increased to 0.2730 d -1 It was 1.82 times that of the single-strain, and the half-life was shortened from 4.63 days to 2.54 days, significantly enhancing the growth and colonization ability of the combined strain.

[0024] (4) The β-cyclodextrin-modified straw-degrading microbial complex of the present invention was applied to the remediation of petroleum-contaminated soil and showed excellent remediation effect under the combined pollution conditions of pyrene and petroleum hydrocarbons. After 90 days of remediation, under a pollution gradient of 100+1000 mg / kg, the removal rate of the combined remediation group was 73.76%, which was slightly higher than that of the bio-enhanced control group (71.95%); under a pollution gradient of 100+2000 mg / kg, the removal rate of the combined remediation group was 61.19%, which was 2.03 percentage points higher than that of the control group (59.16%); under a pollution gradient of 100+4000 mg / kg, the removal rate of the combined remediation group was 53.43%, which was 4.01 percentage points higher than that of the control group (49.42%); under a high pollution load of 100+8000 mg / kg, the removal rate of the combined remediation group reached 59.01%, which was significantly higher than that of the control group (38.31%) by 20.7 percentage points. The above results indicate that the present invention is highly applicable to complex pollution with high load and high-cyclic aromatic hydrocarbons, and the higher the pollution load, the more significant the relative improvement effect.

[0025] (5) β-cyclodextrin-modified straw combined with bioremediation improves the removal rate of pollutants, improves the soil physicochemical environment and nutrient content, promotes soil particle cementation and aggregation, and is conducive to the restoration of soil ecological functions. Attached Figure Description

[0026] Figure 1 These are scanning electron microscope (SEM) images of straw before and after β-cyclodextrin modification according to the present invention, wherein (a) is the original straw and (b) is the β-cyclodextrin modified straw.

[0027] Figure 2 The images show the Fourier transform infrared (FTIR) spectra of straw before and after β-cyclodextrin modification according to this invention.

[0028] Figure 3 The graphs show the degradation performance of modified straw combined with microorganisms under different modification parameters. (a) is the curve of the residual concentration of petroleum hydrocarbons over time, (b) is the statistical graph of the final degradation rate and half-life, and (c) is the comparison graph of the dry weight of the organisms in each system.

[0029] Figure 4 This is a graph showing the change in residual concentration of petroleum hydrocarbons over time during the remediation of petroleum-contaminated soil.

[0030] Figure 5 The diagram shows the changes in soil physicochemical properties during the remediation process, where (a) represents the change in redox potential (ORP), (b) represents the change in electrical conductivity (EC), and (c) represents the particle size composition of soil aggregates.

[0031] Figure 6The diagram shows the changes in soil nutrients during the remediation process, where (a) represents the change in available phosphorus (AP) and (b) represents the change in available nitrogen (AN).

[0032] Figure 7 This is a graph showing the changes in soil extracellular polymeric substances (EPS) content during the remediation process. Detailed Implementation

[0033] The technical solution of this application will be further described in detail below with reference to specific embodiments.

[0034] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0035] Example 1: Preparation of β-cyclodextrin-modified straw

[0036] A method for preparing β-cyclodextrin-modified straw includes the following steps:

[0037] S1. After crushing the corn stalks, add them to an alkaline solution for alkaline modification treatment, filter, wash, and dry to obtain alkaline modified stalks.

[0038] S2. Add the alkali-modified straw obtained in step S1 to a buffer solution, add β-cyclodextrin and a crosslinking agent to carry out a grafting modification reaction. After the reaction is completed, wash and dry to obtain β-cyclodextrin-modified straw.

[0039] Specifically: Take corn stalks, remove impurities, cut into small sections, wash, dry, crush, and pass through a 2mm sieve. Accurately weigh the crushed corn stalks and add them to a 0.5M NaOH solution at a material-to-liquid ratio of 1:30 (g / mL). Place the solution in a magnetically stirred water bath and keep it at 50℃ for 12 hours. After the reaction is complete, filter, wash with running water until neutral, and then dry at 80℃ to obtain alkali-modified stalks.

[0040] Take 1.0 g of the above-mentioned alkali-modified dried straw and add it to 20 mL of 2-morpholinoethanesulfonic acid (MES) buffer solution with pH=5.5. Add 0.15 mmol / L of β-cyclodextrin, and then slowly add propylene oxide as a crosslinking agent at a molar ratio of 1:3 for β-cyclodextrin. React in a magnetically stirred water bath at room temperature for 6 h. After the reaction is complete, repeatedly rinse the modified straw with deionized water to remove free β-cyclodextrin and unreacted crosslinking agent, and dry it at 40 °C to constant weight to obtain β-cyclodextrin-modified straw.

[0041] Morphological characterization: Scanning electron microscopy was performed on the original straw and the β-cyclodextrin-modified straw prepared in this example. The results are as follows: Figure 1 As shown. By Figure 1 As can be seen in (a), the original straw surface is relatively smooth and its structure is intact; Figure 1 As can be seen in (b), after alkali modification and β-cyclodextrin grafting modification, the surface of the straw becomes rough, with obvious attachments and pore structures, which is conducive to the attachment and colonization of microorganisms and the adsorption and enrichment of pollutants.

[0042] Structural characterization: Infrared spectroscopy analysis was performed on the original straw and the β-cyclodextrin-modified straw prepared in this example. The results are as follows: Figure 2 As shown in the image, compared with the original straw, the modified straw showed new characteristic absorption peaks in the spectrum, indicating that β-cyclodextrin has been successfully grafted onto the straw surface through chemical bonds.

[0043] Example 2: Preparation of β-cyclodextrin-modified straw-degrading microbial complex

[0044] The β-cyclodextrin-modified straw pellets prepared in Example 1 were sterilized and then soaked in a proliferation medium for 3 hours at a liquid-to-solid ratio of 10.0 mL:1.0 g. The proliferation medium was a mixture of PDB and LB media. The PDB medium consisted of 4.0 g / L potato extract and 20.0 g / L glucose; the LB medium consisted of 10.0 g / L NaCl, 10.0 g / L peptone, and 5.0 g / L yeast extract. The PDB and LB media were mixed at a volume ratio of 1:1.

[0045] The degrading bacterial strain (a combination of Trichoderma seabuckthorn and Pseudomonas aeruginosa) was inoculated at a rate of 10% (m:v), and 2% proliferation medium was added every 24 hours. The strain was then cultured at 30℃ for 72 hours to obtain the β-cyclodextrin modified straw-degrading bacterial strain consortium.

[0046] Example 3: Degradation performance of β-cyclodextrin-modified straw combined with microbial strains on petroleum hydrocarbons

[0047] Oligotrophic medium (containing 1% PDB, 0.5% yeast extract, 0.5% glucose, and 0.02% MSM) and MSM medium were prepared and sterilized at 121℃ for 30 min before cooling. After inoculating the medium with a 10% (v / v) inoculum of degrading bacteria, 1 g / L of virgin straw, 0.5M alkali-modified straw, and 0.05 mmol / L, 0.15 mmol / L, and 0.30 mmol / L β-cyclodextrin-modified straw (prepared according to Example 1) were added, and the mixture was incubated at 30℃. The residual concentration of petroleum hydrocarbons in the culture system was measured, and the degradation rate was calculated. After destructive sampling, the samples were centrifuged, dried, and weighed to calculate the dry biomass.

[0048] Results and Analysis: Figure 3As shown, combining different modified straws significantly affects the degradation behavior of degrading bacteria on petroleum pollutants.

[0049] Depend on Figure 3 As shown in Figure (a), the residual concentration of petroleum hydrocarbons over time indicates that the degrading bacteria system without straw (control group) achieved a removal rate of approximately 76.9% within 10 days; the removal rate of the original straw-loaded system increased to 84.4%; the removal rate of the 0.5M alkali-modified straw system increased to 91.4%; and the 0.15 mmol β-cyclodextrin-modified straw system maintained the lowest residual pollutant concentration throughout the entire reaction cycle, achieving a removal rate of 94.6% after 10 days, significantly superior to other treatment systems. Compared to the bacteria-only system, the degradation rate of the 0.15 mmol β-cyclodextrin-modified straw combined system increased by 17.7 percentage points. The degradation rate decreased in the 0.30 mmol β-cyclodextrin group, indicating that excessively high β-cyclodextrin concentrations may affect the degradation effect due to overly strong inclusion interactions or limited substrate mass transfer.

[0050] from Figure 3 As shown in Figure (b), the final degradation rate and half-life statistics indicate that the pollutant degradation process in each treatment system conforms to a pseudo-first-order reaction kinetic model. The rate constant k of the biodegradation system is 0.1497 d. -1 The half-life was 4.63 days; after fortification with raw straw and 0.5M alkali-modified straw, the k-values ​​increased to 0.1843 and 0.2220 days, respectively. -1 The straw-modified system with 0.15 mmol β-cyclodextrin showed the best performance, with a k value of 0.2730 d. -1 It is 1.82 times that of the bacterial culture system alone, and its half-life is shortened to 2.54 days.

[0051] Depend on Figure 3 As shown in the biomass comparison diagram (c), the biomass of the 0.15 mmol β-cyclodextrin-modified straw system is significantly higher than that of the other groups. Calculations show that the adsorption capacity of the original straw for petroleum hydrocarbons is 0.34 mg / g, while the adsorption capacity of the 0.15 mmol β-cyclodextrin-modified straw prepared in this invention is increased to 2.06 mg / g. Simultaneously, the microbial biomass in the 0.15 mmol β-cyclodextrin-modified straw system is 2.42 times higher than that of the degrading bacteria system without straw.

[0052] Combination Figure 1 and Figure 2 The characterization results show that alkali treatment improves the pore structure and surface properties of straw, and β-cyclodextrin graft modification improves the apparent solubility of hydrophobic pollutants through the inclusion effect of its hydrophobic cavity. It constructs a coupled microenvironment of "adsorption-slow release-microbial utilization" on the surface of straw carrier, thereby significantly enhancing the continuous degradation ability of the strain.

[0053] Example 4: Remediation of Petroleum-Contaminated Soil Using β-Cyclodextrin-Modified Straw Combined with Microbial Systems

[0054] Preparation of contaminated soil: The test soil was collected from clean soil, specifically brown soil. After removing stones and plant debris, the soil was air-dried, ground, and sieved through a 2mm sieve. Contamination gradients for pyrene and petroleum hydrocarbons were set at 100, 100+1000, 100+2000, 100+4000, and 100+8000 mg / kg. Pyrene and petroleum hydrocarbons were accurately weighed according to the target concentrations and dissolved in a small amount of n-hexane. A portion of the soil was first thoroughly ground and premixed with the contaminants, then repeatedly mixed with the remaining soil. The contaminated soil samples were left to stand in a fume hood until the solvent completely evaporated, then aged at 25℃ in the dark for 30 days. During aging, the soil was turned over every 5 days, and sterile water was added.

[0055] Remediation Experiment: The modified straw-degrading microbial consortium prepared in Example 2 was applied to the artificially contaminated soil at a dosage of 10%, while a free degrading microbial consortium (without modified straw) was set up as a biofortification control. The soil moisture content was maintained at 30% of field capacity by regular weighing and water replenishment. Sampling was conducted regularly to measure the degradation of petroleum hydrocarbons and changes in soil physicochemical properties.

[0056] Results and Analysis: The petroleum hydrocarbon removal effect is as follows: Figure 4 As shown, under pollution gradients of 100+1000 mg / kg, the 90-day removal rates of the bio-augmentation group and the co-remediation group were 71.95% and 73.76%, respectively; at 100+2000 mg / kg, they were 59.16% and 61.19%, respectively; at 100+4000 mg / kg, they were 49.42% and 53.43%, respectively; and at 100+8000 mg / kg, they were 38.31% and 59.01%, respectively. These results indicate that the bio-augmentation efficiency is further improved after combining β-cyclodextrin-modified straw, especially under high pollution loads (8000 mg / kg), where the removal rate of the co-remediation group was 20.7 percentage points higher than that of the bio-augmentation group, demonstrating that the method of this invention has strong applicability to high-concentration, high-cyclic aromatic hydrocarbon complex pollution.

[0057] Changes in soil physicochemical properties: such as Figure 5 As shown, compared with biofortification, the β-cyclodextrin-modified straw combined with bioremediation treatment reduced the overall ORP ( Figure 5 a) and EC ( Figure 5 (b) It promotes the transformation of soil to a relatively reducing microenvironment; at the same time, it promotes the transformation of fine particles into large aggregates, with the proportion of aggregates larger than 2 mm increasing from 50.6% to 51.21% in bioaugmentation, while the proportion of particles smaller than 0.2 mm decreased from 3.6% to 2.0%. Figure 5 c) The degree of soil particle cementation and aggregation is enhanced.

[0058] Changes in soil nutrients: such as Figure 6 As shown, the combined treatment has an effect on available phosphorus (AP, Figure 6 a) The mid-to-late stage maintenance effect was prominent; in the petroleum hydrocarbon group, the AP value rebounded to 3.23 mg / kg at 90 days, which was 13.9% higher than that of biofortification during the same period; for alkaline nitrogen (AN), Figure 6 b) This is characterized by rapid activation in the early stage and continuous assimilation and consumption in the later stage, reflecting the enhancing effect of the combined system on nitrogen turnover and microbial metabolism.

[0059] Extracellular polymeric changes: such as Figure 7 As shown, the combined treatment promoted the early secretion and component remodeling of EPS, which is more conducive to the construction of biomembrane framework, cell attachment and microenvironment buffering.

[0060] The above results indicate that the β-cyclodextrin-modified straw combined with bioremediation of this invention not only enhances the pollution degradation capacity, but also simultaneously improves the conditions for restoring soil ecological functions through adsorption buffering, inclusion solubilization, and microhabitat construction.

[0061] Comparative Example 1

[0062] The difference from Example 3 is that only the degrading microbial strain was used without adding any straw carrier. The results are as follows... Figure 3 As shown, the degradation rate was only 76.9% after 10 days, indicating that the introduction of straw carriers plays an important role in improving degradation performance.

[0063] Comparative Example 2

[0064] The difference from Example 3 is that: unprocessed straw (without alkali modification or β-cyclodextrin modification) was used to support the degrading bacterial strain. The results are as follows... Figure 3 As shown, the degradation rate after 10 days was 84.4%, which is lower than the 94.6% of the present invention, indicating that alkali modification and β-cyclodextrin grafting modification have a synergistic effect on performance improvement.

[0065] The β-cyclodextrin-modified straw and its admixture of the present invention can be used for in-situ or ex-situ bioremediation of petroleum-contaminated soils, and are particularly suitable for the remediation of soils contaminated with medium to high concentrations of petroleum hydrocarbons. The raw materials for this invention are widely available (corn straw is agricultural waste, and β-cyclodextrin is a starch derivative), the preparation process is simple, the cost is low, and it is environmentally friendly, showing broad prospects for industrial application.

[0066] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for preparing β-cyclodextrin-modified straw, characterized in that, Includes the following steps: S1. After crushing the corn stalks, add them to an alkaline solution for alkaline modification treatment, filter, wash, and dry to obtain alkaline modified stalks. S2. Add the alkali-modified straw obtained in step S1 to a buffer solution, add β-cyclodextrin and a crosslinking agent to carry out a grafting modification reaction. After the reaction is completed, wash and dry to obtain β-cyclodextrin-modified straw.

2. The method for preparing β-cyclodextrin-modified straw according to claim 1, characterized in that, The alkaline solution mentioned in step S1 is a 0.5M NaOH solution, the material-to-liquid ratio for alkali modification treatment is 1:30 g / mL, the treatment temperature is 50℃, and the treatment time is 12h.

3. The method for preparing β-cyclodextrin-modified straw according to claim 2, characterized in that, The buffer solution in step S2 is a 2-morpholine ethanesulfonic acid buffer solution with pH=5.5, the concentration of β-cyclodextrin is 0.15 mmol / L, the crosslinking agent is propylene oxide, and the molar ratio of β-cyclodextrin to propylene oxide is 1:

3.

4. The method for preparing β-cyclodextrin-modified straw according to claim 3, characterized in that, The grafting modification reaction described in step S2 is carried out at room temperature for 6 hours.

5. A β-cyclodextrin-modified straw-degrading microbial complex, characterized in that, The invention comprises β-cyclodextrin-modified straw prepared by the method of any one of claims 1-4 and a degrading bacterial system loaded thereon, wherein the degrading bacterial system is a combination of Trichoderma seabuckthorne and Pseudomonas aeruginosa.

6. The β-cyclodextrin-modified straw-degrading microbial complex according to claim 5, characterized in that, The consortium is prepared by the following method: β-cyclodextrin-modified straw prepared by any one of claims 1-4 is sterilized, then soaked in a proliferation medium, and the degradation strain is inoculated at an inoculation rate of 10% m:v and cultured at 30°C for 72 h.

7. The β-cyclodextrin-modified straw-degrading microbial complex according to claim 6, characterized in that, The proliferation medium is a mixed medium of PDB and LB, with a liquid-to-solid ratio of 10.0 mL: 1.0 g.

8. A bioremediation method for petroleum-contaminated soil, characterized in that, The β-cyclodextrin-modified straw-degrading microbial complex according to any one of claims 5-7 is applied to petroleum-contaminated soil.

9. The bioremediation method for petroleum-contaminated soil according to claim 8, characterized in that, The application rate of the β-cyclodextrin-modified straw-degrading microbial complex was 10% of the mass of the petroleum-contaminated soil.

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