Self-adaptive ecological restoration response composite material as well as preparation method and application thereof

Abstract

The invention discloses a self-adaptive ecological restoration response composite material as well as a preparation method and application thereof. The composite material is prepared by mixing a biopolymer film solution and the modified biochar core and then volatilizing a solvent. The composite material disclosed by the invention can effectively degrade organic pollutants in soil in a high saline-alkaline environment, is high in stability, and can cooperate with multiple remediation mechanisms of plants to improve the degradation efficiency of the organic pollutants, improve the saline-alkaline degree of the soil and play a role in remediating the soil. The preparation method of the material is simple, low in cost and suitable for large-scale popularization and application.

Description

TECHNICAL FIELD

[0001] The present application relates to an ecological restoration material, in particular to a self-adaptive ecological restoration response composite material, and also relates to a preparation method thereof and application in restoring contaminated soil, and belongs to the technical field of soil restoration. BACKGROUND

[0002] In China, the problem of oil pollution is prominent in the process of oil exploitation, storage and processing, especially organic pollutants such as petroleum hydrocarbons and polycyclic aromatic hydrocarbons. These pollutants remain in the soil for a long time and are difficult to remove, and they pose a serious threat to soil structure and groundwater environment.

[0003] Traditional restoration methods are usually single physical, chemical or biological restoration, while physical and chemical restoration methods have problems such as high cost and possible secondary pollution; biological restoration degrades organic pollutants through microorganisms or plants, but in saline-alkali soil, microbial activity is limited, and the restoration speed is slow, and the efficiency of plant restoration is low. In recent years, combined restoration methods have gradually become a research hotspot. For example, the chemical degradation-physical fixation combined restoration method proposed in CN 107891060 A uses lime, graphite and other physical methods to fix pollutants after chemical degradation by persulfate, avoiding the diffusion of pollutants. However, this method cannot completely degrade deep petroleum hydrocarbon pollution, and the use of persulfate is large, which may cause additional burden to the environment. Plant-microorganism combined restoration as a green restoration technology has become a research hotspot for the restoration of petroleum contaminated soil. For example, patent CN112251373B accelerates the degradation of petroleum hydrocarbons through a bacteria-enzyme composite preparation, improving the restoration effect. Patent CN113458134B improves the bioavailability of petroleum hydrocarbons and further removes pollutants through the combined restoration of biosurfactants and salt-tolerant plants; patent CN106957809B proposes a microbial inoculant that degrades petroleum hydrocarbons through synergistic action and promotes plant growth, achieving efficient restoration. Patent CN109365495A discloses a method for repairing petroleum contaminated soil by coupling microbial plants with biosurfactants loaded on biochar, which repairs the contaminated soil in situ through the combined action of biochar, microorganisms and plants. However, the activity components and ratio of the microbial inoculant in the existing method are relatively strict, and the environmental requirements are also relatively strict, and the use of biosurfactants may have a negative impact on the environment.

[0004] The saline-alkali soil contaminated by oil is usually mixedly contaminated by oil and salt, and the difficulty of remediation lies in that the soil particles are hydrophobic due to the oil contamination, which increases the difficulty of washing salt and inhibits the transmission of water-soluble nutrients, affecting the growth of plants and microorganisms. In saline-alkali soil, the effect of traditional bioremediation and phytoremediation is poor, the metabolism and activity of microorganisms are inhibited, and the remediation efficiency is greatly reduced. Therefore, it is necessary to develop a new combined remediation method to overcome the negative effects of saline-alkali soil, improve the remediation efficiency, reduce the cost, and achieve long-term and efficient remediation. SUMMARY

[0005] In view of the problems existing in the prior art, a first object of the present application is to provide a self-adaptive ecological remediation response composite material. The composite material has strong stability and can adapt to high-saline-alkali environment, and can effectively degrade organic pollutants for a long time.

[0006] A second object of the present application is to provide a preparation method of the self-adaptive ecological remediation response composite material. The method is simple, low in cost and suitable for industrial production.

[0007] A third object of the present application is to provide an application of the self-adaptive ecological remediation response composite material. The composite material is used for remediation of soil contaminated by organic pollutants, which can greatly improve the removal efficiency of organic pollution, and has high stability, and is especially suitable for harsh high-saline-alkali soil environment.

[0008] In order to achieve the above technical purposes, the present application provides a preparation method of a self-adaptive ecological remediation response composite material, which is prepared by mixing a biological polymer membrane solution and a modified biochar core, and then volatilizing the solvent, to obtain the composite material; the modified biochar core comprises biochar, a surfactant and a binder; the biological polymer membrane solution comprises salt-tolerant microbial bacteria and a biological membrane stock solution, and the biological membrane stock solution comprises polyacrylate, acetopyruvate, cellulose acetate phthalate, microbial nutrient solution, hydroxymethyl cellulose salt, adhesive and glycerol.

[0009] Under different pH conditions, the carboxyl groups in the polymer of the composite material of the present application will ionize according to the change of the hydrogen ion concentration in the solution, to form -COO - , thereby enhancing the intermolecular repulsion, expanding the molecular network structure and improving the water absorption, which enables the material to automatically adjust in acidic and alkaline environments, and enhances the swelling performance; in alkaline environment, OH -The high ion concentration helps ionization of the -COOH group, enhances the swelling performance of the material, enables it to absorb more water molecules, forms a more loose structure, and thus improves the repair effect. Under the condition of a salt solution, at a low salt concentration, the polymer exhibits strong hydrophilicity, absorbs water through the electrostatic repulsion between negative ions, and improves the soil water retention capacity; as the salt concentration increases, the salt ions shield the negative ions, the swelling of the material tends to be stable, the soil structure is optimized, and the adaptability of microorganisms (and plants) in a saline-alkali environment is improved. In addition, the biochar in the modified biochar core in the application has strong adsorption capacity and can effectively capture organic pollutants. The surfactant in the modified biochar core has a curling and solubilizing effect, which can promote the migration of organic pollutants in the soil. The modified biochar core and the responsive polymer synergistically adjust the material in a high-salt and high-pH environment, optimize the repair effect, and at the same time avoid secondary pollution. The biodegradation mechanism in the composite material promotes the adaptation of microorganisms to salt and alkali stress by providing a stable microorganism growth microenvironment, thereby enhancing their degradation capacity. Through the multiple repair mechanisms of physical adsorption, chemical modification, and biodegradation, an efficient and synergistic repair system is formed.

[0010] As a preferred scheme, the mass ratio of the bio-polymer membrane solution to the modified biochar core is 4-6:1-1.5.

[0011] As a preferred scheme, the mass ratio of the biochar, the surfactant, and the binder in the modified biochar core is (80-85):(5-8):(10-15).

[0012] As a preferred scheme, the biochar is prepared from biomass raw materials by citric acid surface modification treatment. Soaking the biomass raw materials in a citric acid solution can improve the pore structure of the biochar and introduce surface functional groups to improve its adsorption performance.

[0013] As a preferred scheme, the surfactant is a natural surfactant. The use of a natural surfactant in the application does not cause secondary pollution to the environment and is suitable for synergistic planting of plants to strengthen the removal of organic pollutants.

[0014] As a preferred scheme, the natural surfactant is saponin, including tea saponin, soapnut saponin, etc.

[0015] As a preferred scheme, the binder is a starch-containing substance. The starch-containing substance includes potato powder, corn powder, sweet potato powder, etc.

[0016] As a preferred scheme, the modified biochar core is obtained by mixing, granulating, and mixing the biochar, the surfactant, and the binder.

[0017] As a preferred scheme, the particle size of the modified biochar core is 3-5 mm.

[0018] As a preferred scheme, the saline-alkali resistant microbial bacteria and the biofilm stock solution are mixed according to a mass ratio of 10-15:100 of the saline-alkali resistant microbial bacteria agent to the biofilm stock solution.

[0019] As a preferred scheme, the saline-alkali resistant microbial bacteria include at least one of Bacillus subtilis, Bacillus halodurans, Bacillus licheniformis, Streptomyces hydrocarbonogenes, and Bacillus olelysis.

[0020] As a preferred scheme, the biofilm stock solution contains the following components by mass:

[0021] Polyacrylate 40-45 parts;

[0022] Pyruvate 5-7 parts;

[0023] Cellulose acetate phthalate 2-4 parts;

[0024] Water 55-60 parts;

[0025] Microbial nutrient solution 15-22 parts;

[0026] Hydroxymethyl cellulose salt 3-5 parts;

[0027] Adhesive 2-4 parts;

[0028] Glycerol 1-3 parts.

[0029] The biofilm stock solution with the above-mentioned ratio can effectively improve the adaptability and stability of the composite material and improve the degradation capacity of the material for organic pollutants.

[0030] As a preferred scheme, the polyacrylate is sodium polyacrylate.

[0031] As a preferred scheme, the pyruvate is sodium pyruvate.

[0032] As a preferred scheme, the hydroxymethyl cellulose salt is sodium hydroxymethyl cellulose.

[0033] As a preferred scheme, the adhesive is polyvinyl alcohol solution. The mass concentration of the polyvinyl alcohol solution is 3-6%.

[0034] As a preferred scheme, the microbial nutrient solution includes glucose, proteose peptone, acid hydrolyzed casein, potassium hydrogen phosphate, trehalose, sodium glutamate, iron salt, and calcium salt.

[0035] As a preferred scheme, the concentration of glucose is 1-3 g / L.

[0036] As a preferred scheme, the concentration of the protein peptone is 1-3 g / L.

[0037] As a preferred scheme, the concentration of the acid hydrolysis casein is 1-3 g / L.

[0038] As a preferred scheme, the concentration of potassium hydrogen phosphate is 0.5-2.5 g / L.

[0039] As a preferred scheme, the concentration of trehalose is 1-3 g / L.

[0040] As a preferred scheme, the concentration of sodium glutamate is 0.2-1 g / L.

[0041] As a preferred scheme, the concentration of the iron salt is 0.05-0.15 g / L.

[0042] As a preferred scheme, the concentration of the calcium salt is 0.1-0.5 g / L.

[0043] The application further provides a self-adaptive ecological remediation response composite material prepared by the above method.

[0044] The application further provides an application of the self-adaptive ecological remediation response composite material, which is used for degrading organic pollutants in soil.

[0045] As a preferred scheme, the organic pollutants are petroleum hydrocarbon pollutants.

[0046] As a preferred scheme, the pH value of the soil is 7-9, and the salt content of the soil is 20-40 g / kg.

[0047] As a preferred scheme, the application amount of the composite material is 3-9 wt% of the contaminated soil.

[0048] As a preferred scheme, salt-tolerant plants are planted in the contaminated soil at the same time, and further preferably salt-tolerant plants capable of degrading organic pollutants. The plants include Suaeda salsa, Salicornia, Tamarix and the like. The composite material of the present application not only can adsorb petroleum hydrocarbon pollutants, but also can promote the migration of petroleum hydrocarbons in the soil by enhancing the solubilization effect of the surfactant, and under the combined action of microorganisms and plants, the degradation of petroleum hydrocarbons in the vicinity of the plant root system is realized, the diffusion of pollutants is reduced, and secondary pollution is avoided. The plant remediation mechanism can further promote the activity and metabolism of microorganisms by secreting organic substances through the root system, accelerate the degradation of pollutants.

[0049] Compared with the prior art, the present application has the following advantages:

[0050] (1) The responsive polymer in the composite material has a multiple response mechanism, which can automatically adjust its structure and function according to the pH value and salt content of the soil, thereby effectively reducing the risk of direct exposure of microorganisms to high saline soil, avoiding the damage caused by ion toxicity and water loss, significantly enhancing the survival ability of microorganisms in complex environment, improving the stability and tolerance of the material, and greatly enhancing the degradation ability of organic pollutants;

[0051] (2) Through multiple remediation mechanisms such as physical adsorption, chemical modification, biodegradation and phytoremediation, a high-efficiency and synergistic remediation system is formed. Compared with traditional remediation methods, the present application significantly improves the remediation efficiency and long-term stability. The composite material in high-saline environment reduces the inhibition of salt on plants and microorganisms through multiple remediation mechanisms, and maintains the sustainability and efficiency of soil remediation. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 The method flowchart of Example 1 of the present application. DETAILED DESCRIPTION

[0053] The technical solutions of the present application will be described in detail below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0054] The present application selects a flat and regular plot for a small plot test in a saline-alkali site contaminated by oil in Kashi region of Xinjiang. The sampling analysis and detection show that the soil pH is 8.93; the petroleum hydrocarbon content is 3251mg / kg; and the soil salt content is 37.44mg / kg.

[0055] Example 1

[0056] Preparation process of the responsive composite material:

[0057] (1) Preparation of the biological polymer membrane solution: the salt-tolerant and alkali-tolerant microbial agent is mixed with the biological membrane original solution at a ratio of 15:100.

[0058] The biological membrane original solution is prepared according to the following mass fraction of raw materials:

[0059] Sodium polyacrylate 42 parts, sodium pyruvate 6 parts, cellulose acetate phthalate 3 parts, deionized water 58 parts, nutrient solution 18 parts, sodium hydroxymethyl cellulose 4 parts, polyvinyl alcohol (PVA) 3 parts (prepared as a solution). Mix and stir with a low-speed stirrer (100 rpm), and add 2 parts of glycerol during stirring. The preparation of polyvinyl alcohol solution is as follows: take polyvinyl alcohol (PVA) and add 1000 mL of distilled water, control the mass concentration of PVA to be 4wt%, stir and heat to 65°C, completely dissolve, continue to stir for 20 minutes, and cool to room temperature. The preparation process of the nutrient substance is as follows: 2.0 g of glucose, 2.0 g of proteose peptone, 2.0 g of acid hydrolysis casein, 1.0 g of potassium hydrogen phosphate, 2.0 g of trehalose, 0.5 g of sodium glutamate, 0.1 g of iron salt (FeSO4·7H2O), and 0.2 g of calcium salt (CaCl2) are added one by one to 1000 mL of distilled water, and stirred at room temperature until all the ingredients are completely dissolved. Then the solution is filtered through a 0.45 μm filter membrane to remove any undissolved particles and ensure the solution is clear and uniform.

[0060] The salt-tolerant and alkali-tolerant microbial original agent contains multiple strains, and the specific strains and mass fraction ratio are as follows: Bacillus subtilis 35%, Bacillus halodurans 25%, oil-degrading Bacillus subtilis 25%, petroleum hydrocarbon-degrading Streptomyces spp. 10%, and Bacillus licheniformis 5% mixed bacterial solution.

[0061] 100 mL of the above mixed bacterial solution is added to 1000 mL of liquid medium for bacterial culture, and the medium composition is as follows: glucose 2 g, yeast extract 2 g, bacteriological proteose peptone 2 g, acid hydrolysis casein 2 g, K2HPO3·3H2O 1 g, sodium pyruvate 1 g, MgSO4·7H2O 0.2 g, dissolved in 1000 mL of distilled water. Culture at a suitable temperature (35°C) for 24 hours, dilute the bacterial solution and count to ensure that the bacterial solution concentration is 4×10 9After the cfu / mL, centrifugal precipitation was performed. A centrifuge was used, with a speed of 5000 rpm and a centrifugation time of 18 minutes. The bacterial agent was washed twice with sterile deionized water to remove residual components in the culture medium, and the obtained culture agent was mixed with the biofilm original solution at a mass ratio of 15:100.

[0062] (2) Preparation of modified biochar core

[0063] Take 210 g of citric acid (C6H8O7H2O) and add distilled water to 1000 mL to prepare a 1.0 mol / L citric acid solution. Mix the oil tea shell biochar with the citric acid solution at a mass ratio of 1:1, and oscillate at 25°C for 2 hours to modify the surface functional groups. Wash the excess solution with deionized water and dry at 60°C for 12 hours to obtain the surface-modified oil tea shell biochar.

[0064] Dry and crush the oil tea dregs, mix 10 g of oil tea dregs powder with 80% ethanol solution at a ratio of 1:10 in a 70°C water bath for 2 hours. Concentrate and vacuum dry the extract to obtain oil tea saponin.

[0065] Mix the above surface-modified oil tea shell biochar, oil tea saponin and potato powder at a mass ratio of 85:5:10, add water and stir until the water content is 50%, then granulate and dry to obtain modified biochar core with a particle size of 4.0 mm.

[0066] (3) Preparation of composite material

[0067] Mix the bio-polymer film solution and the modified biochar core at a mass ratio of 5:1, and dry at 40-50°C for 4-6 hours to obtain the responsive composite material.

[0068] (4) Application of composite material

[0069] Apply 3wt% of the responsive composite material to the contaminated saline-alkali soil, and apply calcium superphosphate 18g / m² and humic acid fertilizer 6.5kg / m² as base fertilizer at the same time. Mix well after plowing, and water for 2-3 days; transplant the Suaeda salsa seedlings according to the spacing of 20cm x 20cm, and carry out routine weeding, pest control and irrigation management. After 90 days of Suaeda salsa transplantation, sample the soil for soil testing, measure the concentration of petroleum hydrocarbon, pH value and soil salt content, and record and analyze the repair effect.

[0070] Example 2

[0071] Prepare the composite material by the method of Example 1 and apply it, except that 6wt% of the responsive composite material is applied to the contaminated saline-alkali soil.

[0072] Example 3

[0073] The composite material is prepared and applied by the method of Example 1, except that 9wt% of the responsive composite material is applied to the contaminated saline-alkali soil.

[0074] Example 4

[0075] The composite material is prepared and applied by the method of Example 1, except that Suaeda salsa is not planted.

[0076] Example 5

[0077] The composite material is prepared and applied by the method of Example 2, except that Suaeda salsa is not planted.

[0078] Example 6

[0079] The composite material is prepared and applied by the method of Example 3, except that Suaeda salsa is not planted.

[0080] Example 7

[0081] The composite material is prepared and applied by the method of Example 2, except that the mass ratio of the biopolymer film solution to the modified biochar core is 4:1.5.

[0082] Example 8

[0083] The composite material is prepared and applied by the method of Example 2, except that the mass ratio of the biopolymer film solution to the modified biochar core is 6:1.

[0084] Comparative Example 1

[0085] Calcium superphosphate 18g / m2 and humic acid fertilizer 6.5kg / m2 are applied together to the contaminated saline-alkali soil as base fertilizer, and after mixing evenly by ploughing, water is maintained for 2-3 days; Suaeda salsa seedlings are transplanted according to a plant spacing of 20cm x 20cm, and routine weeding, insect prevention and drainage water management are carried out. After 90 days of Suaeda salsa transplantation, the soil is sampled for soil detection, and the concentration of petroleum hydrocarbon, pH value and soil salt content are measured, and the repair effect is recorded and analyzed.

[0086] CK (blank experiment)

[0087] Calcium superphosphate 18g / m2 and humic acid fertilizer 6.5kg / m2 are applied together to the contaminated saline-alkali soil as base fertilizer, and after mixing evenly by ploughing, water is maintained for 2-3 days, and after 90 days, the soil is sampled for soil detection, and the concentration of petroleum hydrocarbon, pH value and soil salt content are measured, and the repair effect is recorded and analyzed.

[0088] The soil detection results of each example and comparative example are shown in Table 1.

[0089]

[0090] As can be seen from Table 1, compared with the blank control group (CK), the composite material of the application can effectively remove petroleum hydrocarbon in high saline-alkali soil, and within a certain range, the removal rate of petroleum hydrocarbon is improved with the increase of the application amount of the composite material, and beyond the range, the increase of the addition amount of the composite material has no obvious improvement on the removal rate of petroleum hydrocarbon; examples 1-3 and examples 7-8 show that the multiple repair mechanism of the composite material combined with plants has a better effect on the removal of petroleum hydrocarbon, and can also effectively reduce the salt content of the soil and improve the soil salinity, wherein the responsive composite material can promote cation exchange, accelerate the absorption and transformation of salt in the soil by alkali bush through its root system, the alkali bush can prevent the water evaporation of the responsive composite material in the soil from being too much, maintain the swelling state, and promote the saponin component in the responsive composite material to further dissolve the petroleum hydrocarbon pollutants. Therefore, the combined application of the responsive composite material and the alkali bush plant can not only effectively degrade the petroleum hydrocarbon pollutants in the soil, but also reduce the salt content of the soil, improve the acidity and alkalinity of the soil, and improve the long-term stability of the repair effect.

[0091] In summary, the method of the application has strong long-term repair potential and ecological safety, and can effectively degrade organic pollutants in high saline-alkali soil.

[0092] Various modifications to these examples will be readily apparent to those skilled in the art, and generic principles defined herein can be applied to other examples without departing from the spirit or scope of the application. Thus, the present application is not to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an adaptive ecological restoration response composite material, characterized in that: The modified biochar core is obtained by mixing the biopolymer membrane solution with the modified biochar core and then evaporating the solvent. The modified biochar core contains biochar, surfactant, and binder. The biopolymer membrane solution contains salt-tolerant microorganisms and biofilm stock solution. The biofilm stock solution contains polyacrylate, pyruvate, cellulose acetate phthalate, microbial nutrient solution, hydroxymethyl cellulose salt, adhesive, and glycerol.

2. The method for preparing an adaptive ecological restoration response composite material according to claim 1, characterized in that: The mass ratio of the biopolymer membrane solution to the modified biochar core is 4~6:1~1.5; The mass ratio of biochar, surfactant and binder in the modified biochar core is (80~85):(5~8):(10~15).

3. The method for preparing an adaptive ecological restoration response composite material according to claim 1 or 2, characterized in that: The biochar is prepared from biomass raw materials through citric acid surface modification treatment. The surfactant is a natural surfactant; the natural surfactant is a saponin. The adhesive is a starch-containing substance; The modified biochar core is obtained by granulation of biochar, surfactant and binder.

4. The method for preparing an adaptive ecological restoration response composite material according to claim 1, characterized in that: The salt-tolerant microorganisms and biofilm stock solution are mixed at a mass ratio of 10~15:

100.

5. The method for preparing an adaptive ecological restoration response composite material according to claim 1, characterized in that: The biofilm stock solution comprises the following components in parts by weight: 40-45 parts of polyacrylate; 5-7 parts of pyruvate; 2-4 parts of cellulose acetate phthalate; 55-60 parts water; 15-22 parts of microbial nutrient solution; 3-5 parts of hydroxymethyl cellulose salt; 2-4 parts adhesive; 1-3 parts glycerin.

6. The method for preparing an adaptive ecological restoration response composite material according to claim 1 or 5, characterized in that: The polyacrylate is sodium polyacrylate; Pyruvate is sodium pyruvate; The hydroxymethyl cellulose salt is sodium hydroxymethyl cellulose; The adhesive is a polyvinyl alcohol solution; The microbial nutrient solution includes glucose, peptone, acid-hydrolyzed casein, potassium hydrogen phosphate, trehalose, monosodium glutamate, iron salts, and calcium salts.

7. An adaptive ecological restoration response composite material, characterized in that: Prepared by the method described in any one of claims 1 to 6.

8. The application of the adaptive ecological restoration response composite material according to claim 7, characterized in that: Used to degrade organic pollutants in soil.

9. The application of the adaptive ecological restoration response composite material according to claim 8, characterized in that: The amount of the composite material applied is 3 to 9 wt% of the contaminated soil.

10. The application of the adaptive ecological restoration response composite material according to claim 8 or 9, characterized in that: Salt-tolerant plants are planted in the polluted soil at the same time.

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