Soil remediation conditioner and preparation method thereof

Abstract

The invention provides a soil remediation conditioner and a preparation method thereof, and the soil remediation conditioner is prepared according to the following steps: putting charcoal into a hydrogen peroxide solution, stirring, washing with deionized water, and drying; soaking the dried biochar in a ferric nitrate solution, filtering, transferring into a tubular furnace filled with inert gas, and calcining to obtain nano-iron loaded biochar; and uniformly mixing a solubilizer solution with the nano-iron-loaded biochar suspension, and then carrying out spray drying, so that a solubilizer is uniformly distributed on the surface of the nano-iron-loaded biochar to obtain the soil remediation conditioner. The prepared soil remediation conditioner can reduce the pH value of saline-alkali soil, increase the content of organic matters in the soil, reduce the water-soluble salt content in the soil and reduce the content of organic pollutants in the soil. By adding the soil remediation conditioner, the soil structure can be improved, the soil texture is thinned, soil pores and particle arrangement are improved, and the remediation efficiency of the aged contaminated soil can be improved.

Description

Technical Field

[0001] The present invention relates to the field of environmental management, and specifically relates to a soil remediation conditioner and a preparation method thereof. Background Art

[0002] Salt soil and alkaline soil are collectively referred to as saline-alkali soil and saline soil. The concentration of soluble salts in the soil is high and among the cations, the exchangeable sodium ion content in the total exchange capacity accounts for more than 20% of the soil, which will directly inhibit or harm plant growth.

[0003] The Yellow River Delta is mainly located in Dongying City, Shandong Province. Under the influence of climatic conditions, soil properties, seawater intrusion and other factors, the soil pH in the Yellow River Delta region reaches above 8, and the salt content is about 8g / kg. The soil is poor and severely compacted. In addition, the saline soil area of ​​the Yellow River Delta is seriously polluted with organic matter deficiency and low basic soil fertility.

[0004] At present, the main methods for improving saline-alkali soil at home and abroad include physical improvement, chemical improvement, and biological improvement. Soil improvers refer to substances added to the soil to improve the physical and chemical properties and biological activity of the soil. They can be divided into two categories: inorganic and organic. Inorganic soil improvers include limestone, phosphogypsum, fly ash, etc., and organic improvers include straw, plant residues, composted feces, biochar, etc.

[0005] Biochar, a novel carbon composite material containing high levels of carbon, organic, and inorganic minerals, can improve soil structure and enhance soil fertility. Numerous studies have publicly documented the use of biochar in the remediation of saline-alkali soils. However, the comprehensive remediation capabilities of existing biochar-based saline-alkali soil remediation agents in the saline soils of the Yellow River Delta are very limited, resulting in only modest improvements. Summary of the Invention

[0006] In order to solve the above problems, the present application proposes a method for preparing a soil remediation conditioner, comprising the following steps:

[0007] (1) The biochar was placed in a hydrogen peroxide solution and stirred, then washed with deionized water and dried;

[0008] (2) The dried biochar was immersed in a ferric nitrate solution, filtered, and then transferred to a tube furnace with an inert gas for calcination to obtain biochar loaded with nano-iron (Fe / FeO / Fe3O4);

[0009] (3) The solubilizer solution and the nano-iron-loaded biochar suspension are evenly mixed and then spray-dried, so that the solubilizer is evenly distributed on the surface of the nano-iron-loaded biochar to obtain a soil remediation conditioner.

[0010] The preparation method of the present application is used to load three kinds of nano materials, zero-valent iron, FeO and Fe3O4, on the biochar, wherein the zero-valent iron is mainly contained and the content is more than 60%.

[0011] Further, the concentration of the hydrogen peroxide solution in step (1) is 10-20%, and the mass-volume ratio of the biochar to the hydrogen peroxide solution is 1:(20-40).

[0012] Preferably, the biochar is put into the hydrogen peroxide solution, stirred at 40-60℃ for 2-6h, washed with deionized water, and dried at 40-60℃.

[0013] Further, the concentration of the ferric nitrate solution in step (2) is 10-20%, and the mass ratio of the biochar to the ferric nitrate is 1:(0.5-1).

[0014] Further, the calcination conditions in step (2) are as follows: the calcination temperature is 700-800℃, the calcination time is 1-3h, and the heating rate is 5-9℃ / min.

[0015] Further, the solubilizing agent in step (3) includes one or more combinations of dodecyl polyoxyethylene ether, Tween 80 and sodium dodecyl sulfonate.

[0016] Further, the mass ratio of the solubilizing agent to the biochar loaded with nano iron is 1%-10%.

[0017] Preferably, the spray drying conditions in step (3) are as follows: the drying temperature is 100-150℃, the feeding speed is 10-15ml / min, and the spray pressure is 1-2MPa.

[0018] Further, the surface of the biochar loaded with nano iron obtained in step (2) is further loaded with chitosan, and the steps are as follows: the biochar powder loaded with nano iron is added into a chitosan solution and stirred, a crosslinking agent is added and stirred, the pH of the reaction system is adjusted to 7-9 for reaction, then filtered, washed with deionized water, and dried to obtain the product.

[0019] Further, the chitosan solution with a concentration of 2-5% is obtained by dissolving chitosan in an acetic acid solution with a concentration of 1-3%, and the mass ratio of chitosan to the biochar loaded with nano iron is 1:(3-6).

[0020] Further, the crosslinking agent is glutaraldehyde or sodium tripolyphosphate, and the crosslinking agent accounts for 20-40% of the mass of chitosan.

[0021] Further, the biochar raw material is selected from one or more of corn straw, soybean straw, rice straw, sunflower straw, wood chips and bamboo; and the particle size of the biochar is 50-200 mesh.

[0022] Further, the application can be prepared by a common pyrolysis method, i.e. carbonizing the raw material at 300-500℃ for 3h, cooling and grinding.

[0023] Preferably, the biochar raw material is selected from the group consisting of corn straw, rice straw and wood chips, in a mass ratio of 1:(0.5-0.8):(2-4).

[0024] The application is found through experiments that the soil remediation conditioner prepared by the application is more suitable for application in the treatment of saline-alkali soil, and the addition amount is 1-10wt%.

[0025] The soil conditioner prepared by the application is more suitable for soil remediation in the saline soil area of the Yellow River Delta.

[0026] The application can bring the following beneficial effects:

[0027] 1. The soil remediation conditioner obtained by loading nano-iron on the surface of biochar and then loading a solubilizing agent can adjust the pH of the soil, increase the organic matter content in the soil, reduce the water-soluble salt content in the soil, reduce the content of organic pollutants in the soil, improve the soil structure, make the soil texture finer, improve the soil pore and particle arrangement, and can improve the remediation efficiency of aged contaminated soil.

[0028] 2. Biochar has a large specific surface area and pore structure, which increases the aeration and water permeability of the soil; saline-alkali soil is easy to be compacted, and the porous structure of biochar can improve the porosity, and the nano-particles fill the small pores to enhance the stability of soil aggregation and prevent further compaction.

[0029] 3. Hydrogen peroxide reacts with carbon atoms on the surface of biochar to introduce hydroxyl, carboxyl and carbonyl groups on the surface of biochar, providing more active sites. The smaller pores inside the biochar are dissolved or destroyed, thereby expanding the pore size, increasing the specific surface area and porosity of the biochar, and improving the adsorption performance of the biochar, which is beneficial to the subsequent loading of nano-iron.

[0030] 4, The role of the nano-iron loaded in the application: (1) Increase the surface roughness, strong nutrient adsorption capacity, rich surface functional groups; Increase the porosity, increase the specific surface area of biomass carbon, provide more habitat for microorganisms, retain more C\N as essential nutrients for plant and microbial survival and growth. (2) Zero-valent iron can participate in reduction reaction to reduce sulfate, reduce sulfate in salt, and FeO and Fe3O4 will exchange sodium ions through surface hydroxyl group to reduce the sodium adsorption ratio in soil; The magnetism of Fe3O4 helps to recycle the material and reduce secondary pollution. (3) Load nano-iron on the surface and pores of biochar, and biochar as a carrier provides support to increase dispersibility and effectively prevent nano-iron particles from aggregating. (4) Nano-iron provides iron elements to promote plant growth, and iron oxides have a fixing effect on phosphorus in soil, which can reduce the loss of phosphorus and also affect the microbial community structure to promote the growth of beneficial bacteria and inhibit pathogenic bacteria.

[0031] 5, The role of the solubilizer loaded outside the nano-iron in the application: (1) The solubilizer forms micelles or inclusion complexes to solubilize the organic pollutants (polycyclic aromatic hydrocarbons, petroleum hydrocarbons, etc.) adsorbed in the soil into the liquid phase; The solubilized pollutants contact nano-iron, triggering reduction dehalogenation or Fenton-like oxidation, achieving efficient degradation of organic matter; Biochar adsorbs and enriches pollutants through pores, and solubilizer pulls them into the liquid phase, which is degraded by nano-iron nearby. (2) The solubilizer micelles can adsorb salt ions, combined with the ion exchange capacity of biochar, to reduce the salt concentration of soil solution. (3) The solubilizer reduces the toxicity of pollutants and improves their bioavailability, stimulates the metabolic activity of salt-tolerant degrading bacteria in saline-alkali soil, biochar provides a habitat for microorganisms, and nano-iron acts as an electron shuttle to promote interspecies electron transfer and accelerate anaerobic degradation of pollutants. (4) The hydrophilic group of the solubilizer combines with sodium ions in saline-alkali soil, while the hydrophobic chain captures organic pollutants, achieving simultaneous enrichment of salt and pollutants; Nano-iron oxides complex and fix anion salts such as chloride and sulfate through surface hydroxyl groups, reducing their interference with the degradation process; The solubilizer forms a hydrophilic layer on the surface of biochar, reducing the rapid oxidation and inactivation of nano-iron in high-salt environments, and the carbon skeleton of biochar buffers the salting-out effect of salt on the solubilizer, maintaining the stability of the micelles.

[0032] 6, The soil remediation conditioner prepared in the application can improve the remediation efficiency of aged contaminated soil. Pollutants in aged contaminated soil are often tightly bound to soil particles, and the mass transfer process is limited. The solubilizer further improves the mass transfer conditions of pollutants without affecting the loading effect of nano-iron, and the two work together to improve the remediation efficiency of aged contaminated soil.

[0033] 7、The application is to load chitosan on the surface of nano-iron loaded biochar, and the effect of re-loading a solubilizer: (1) Chitosan is loaded with amino and hydroxyl groups, which preferentially chelate sodium, calcium, magnesium and other ions in saline-alkali soil, reduce the sodium adsorption ratio through ion exchange, and alleviate soil alkalization; (2) Chitosan has cationic properties to adsorb anion salts such as chloride and sulfate, forming a chitosan-salt complex to reduce salt migration to the plant rhizosphere; (3) Chitosan coats nano-iron to form a physical barrier to inhibit the rapid oxidation of nano-iron in a high-salt environment and prolong its reduction activity period; (4) The pH sensitivity of chitosan can achieve slow release of divalent iron ions and trivalent iron ions, avoiding plant toxicity caused by local iron excess; (5) Chitosan fixes the solubilizer through hydrogen bonding or electrostatic interaction to prevent the salt-out effect in a high-salt environment from causing the solubilizer to be detached and ineffective; (6) Chitosan as a natural polysaccharide provides a carbon source for salt-tolerant microorganisms to promote their colonization; Chitosan and biochar together act as a cementing agent to promote the formation of water-stable aggregates in saline-alkali soil, improve aeration and water retention, and can achieve nutrient release, and the weak acidity of chitosan cooperates with the acid production of nano-iron oxidation to neutralize alkaline soil. DETAILED DESCRIPTION

[0034] Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products.

[0035] [Example 1]

[0036] The soil remediation conditioner is prepared by the following preparation method:

[0037] (1) Corn straw is carbonized at 300℃ for 3h, and then ground to a particle size of 200 mesh after cooling to room temperature;

[0038] (2) The biochar is placed in a 10% hydrogen peroxide solution and stirred at 40℃ for 6h, the mass-volume ratio of biochar to hydrogen peroxide solution is 1:20, then washed with deionized water and dried at 40℃;

[0039] (3) The dried biochar is soaked in a 10% iron nitrate solution for 30min, the mass ratio of biochar to iron nitrate is 1:0.5, then filtered and transferred to a tube furnace with nitrogen gas to calcine, the heating rate is 9℃ / min, and the temperature is raised to 700℃ for calcination for 3h;

[0040] (4) Dodecyl polyoxyethylene ether is dissolved in ethanol with a volume ratio of 1:10; and then mixed uniformly with the nano-iron loaded biochar suspension (the volume ratio of nano-iron loaded biochar to ethanol is 1:5) to perform spray drying (the drying temperature is 100℃, the feeding speed is 15ml / min, and the spray pressure is 1MPa), the mass ratio of dodecyl polyoxyethylene ether to nano-iron loaded biochar is 1%, and the soil remediation conditioner is obtained.

[0041] Example 2

[0042] The soil remediation conditioner is prepared by the following preparation method:

[0043] (1) rice straw is carbonized at 500°C for 3h, and after cooling to room temperature, it is ground to a particle size of 50 mesh to obtain biochar;

[0044] (2) the biochar is placed in a 20% hydrogen peroxide solution and stirred at 60°C for 2h, the mass-volume ratio of biochar to hydrogen peroxide solution is 1:40, and then washed with deionized water and dried at 60°C;

[0045] (3) the dried biochar is soaked in a 20% iron nitrate solution for 60min, the mass ratio of biochar to iron nitrate is 1:1, and after filtration, it is transferred to a tube furnace with nitrogen gas to obtain nano-iron-loaded biochar, the heating rate is 5°C / min, and the temperature is raised to 800°C and calcined for 1h;

[0046] (4) Tween 80 is dissolved in ethanol with a volume ratio of 1:5; and the nano-iron-loaded biochar suspension (volume ratio of nano-iron-loaded biochar to ethanol is 1:10) is mixed uniformly, and then spray dried (drying temperature is 150°C, feeding speed is 10ml / min, and spray pressure is 2MPa), the mass ratio of Tween 80 to nano-iron-loaded biochar is 10%, to obtain the soil remediation conditioner.

[0047] Example 3

[0048] The soil remediation conditioner is prepared by the following preparation method:

[0049] (1) soybean straw and bamboo (mass ratio of 1:1) are carbonized at 400°C for 3h, and after cooling to room temperature, they are ground to a particle size of 100 mesh to obtain biochar;

[0050] (2) the biochar is placed in a 10% hydrogen peroxide solution and stirred at 50°C for 3h, the mass-volume ratio of biochar to hydrogen peroxide solution is 1:30, and then washed with deionized water and dried at 50°C;

[0051] (3) the dried biochar is soaked in a 15% iron nitrate solution for 60min, the mass ratio of biochar to iron nitrate is 1:0.8, and after filtration, it is transferred to a tube furnace with nitrogen gas to obtain nano-iron-loaded biochar, the heating rate is 8°C / min, and the temperature is raised to 800°C and calcined for 2h;

[0052] (4) Sodium dodecyl sulfate was dissolved in water at a volume ratio of 1:10, and mixed evenly with the suspension of nano-iron-loaded biochar (volume ratio of nano-iron-loaded biochar to water was 1:10) to perform spray drying (drying temperature was 130°C, feeding speed was 12 ml / min, and spray pressure was 2 MPa), and the mass ratio of sodium dodecyl sulfate to nano-iron-loaded biochar was 2%, to obtain the soil remediation conditioner.

[0053] Example 4

[0054] The soil remediation conditioner was prepared by the following preparation method:

[0055] (1) Corn straw, rice straw, and wood chips (mass ratio was 1:0.5:3) were carbonized at 500°C for 3h, and then ground to a particle size of 100 mesh after cooling to room temperature to obtain biochar;

[0056] (2) The biochar was placed in a 15% hydrogen peroxide solution and stirred at 50°C for 4h, and the mass-volume ratio of biochar to hydrogen peroxide solution was 1:30, and then washed with deionized water and dried at 60°C;

[0057] (3) The dried biochar was placed in a 10% iron nitrate solution and soaked for 40 min, and the mass ratio of biochar to iron nitrate was 1:0.6, and then filtered and transferred to a tube furnace with nitrogen to calcine to obtain nano-iron-loaded biochar, and the heating rate was 6°C / min, and the temperature was raised to 700°C and calcined for 2h;

[0058] (4) Sodium dodecyl sulfate was dissolved in water at a volume ratio of 1:10, and mixed evenly with the suspension of nano-iron-loaded biochar (volume ratio of nano-iron-loaded biochar to water was 1:10) to perform spray drying (drying temperature was 120°C, feeding speed was 10 ml / min, and spray pressure was 1 MPa), and the mass ratio of sodium dodecyl sulfate to nano-iron-loaded biochar was 3%, to obtain the soil remediation conditioner.

[0059] Example 5

[0060] The soil remediation conditioner was prepared by the following preparation method:

[0061] (1) Corn straw, rice straw, and wood chips (mass ratio was 1:0.5:3) were carbonized at 500°C for 3h, and then ground to a particle size of 100 mesh after cooling to room temperature to obtain biochar;

[0062] (2) The biochar was placed in a 15% hydrogen peroxide solution and stirred at 50°C for 4h, and the mass-volume ratio of biochar to hydrogen peroxide solution was 1:30, and then washed with deionized water and dried at 60°C;

[0063] (3) The dried biochar is soaked in a 10% ferric nitrate solution for 40 minutes, with a mass ratio of biochar to ferric nitrate of 1:0.6. After filtration, the biochar is transferred to a tube furnace filled with nitrogen gas for calcination, with a heating rate of 6°C / min, and calcination at 700°C for 2 hours;

[0064] (4) Chitosan is dissolved in a 1% acetic acid solution to obtain a 2% chitosan solution. The chitosan solution is added to the nano-iron-loaded biochar and stirred at 40°C for 30 minutes, with a mass ratio of chitosan to nano-iron-loaded biochar of 1:3. Glutaraldehyde (20% of the mass of chitosan) is added, and the pH of the system is adjusted to 7 for a reaction time of 30 minutes. After filtration, the product is washed with deionized water and dried to obtain a nano-iron biochar material loaded with chitosan.

[0065] (5) Sodium dodecyl sulfonate is dissolved in water at a volume ratio of 1:10. The mixture is uniformly mixed with the nano-iron biochar material loaded with chitosan (volume ratio of nano-iron biochar material loaded with chitosan to water is 1:10), and then spray dried (drying temperature is 120°C, feeding speed is 10 ml / min, and spray pressure is 1 MPa). The mass ratio of sodium dodecyl sulfonate to nano-iron biochar material loaded with chitosan is 3%. A soil remediation conditioner is obtained.

[0066]

Example 6

[0067] The difference between Example 6 and Example 5 is only in step (4), and the other steps are not repeated:

[0068] (4) Chitosan is dissolved in a 3% acetic acid solution to obtain a 5% chitosan solution. The chitosan solution is added to the nano-iron-loaded biochar and stirred at 40°C for 30 minutes, with a mass ratio of chitosan to nano-iron-loaded biochar of 1:6. Sodium tripolyphosphate (40% of the mass of chitosan) is added, and the pH of the system is adjusted to 9 for a reaction time of 30 minutes. After filtration, the product is washed with deionized water and dried to obtain a nano-iron biochar material loaded with chitosan.

[0069]

Example 7

[0070] The difference between Example 7 and Example 5 is only in step (4), and the other steps are not repeated:

[0071] (5) Chitosan is dissolved in a 2% acetic acid solution to obtain a 4% chitosan solution. The chitosan solution is added to the nano-iron-loaded biochar and stirred at 50°C for 30 minutes, with a mass ratio of chitosan to nano-iron-loaded biochar of 1:4. Glutaraldehyde (30% of the mass of chitosan) is added, and the pH of the system is adjusted to 8 for a reaction time of 30 minutes. After filtration, the product is washed with deionized water and dried to obtain a nano-iron biochar material loaded with chitosan.

[0072] Comparative Example 1

[0073] The difference from Example 1 is that there is no step (2), and the remaining steps are exactly the same as steps (1), (3), (4) of Example 1, which will not be repeated here.

[0074] Comparative Example 2

[0075] The difference from Example 1 is that there is no step (3).

[0076] The soil remediation conditioner is prepared by the following preparation method:

[0077] (1) Corn straw is carbonized at 300°C for 3h, and after cooling to room temperature, it is ground to a particle size of 200 mesh to obtain biochar;

[0078] (2) The biochar is placed in a 10% hydrogen peroxide solution and stirred at 40°C for 6h, the mass volume ratio of biochar to hydrogen peroxide solution is 1:20, then washed with deionized water and dried at 40°C;

[0079] (3) The dodecyl polyoxyethylene ether is dissolved in ethanol with a volume ratio of 1:10; After mixing evenly with the biochar suspension (volume ratio of biochar to ethanol is 1:5), spray drying is carried out (drying temperature is 100°C, feeding speed is 15ml / min, spray pressure is 1MPa), the mass ratio of dodecyl polyoxyethylene ether to biochar is 1%, to obtain soil remediation conditioner comparative sample 1#.

[0080] Comparative Example 3

[0081] The difference from Example 1 is that there is no step (4), and the remaining steps are exactly the same as steps (1), (2), (3) of Example 1, which will not be repeated here.

[0082] Comparative Example 4

[0083] The difference from Example 3 is that Comparative Example 4 stirs and mixes the same mass ratio of biochar, nano-iron and sodium dodecyl sulfate as in Example 3 to obtain a soil remediation conditioner.

[0084] Characterization

[0085] The saline-alkali soil is taken from the cultivated layer of soil in the Hekou District of Dongying City, Shandong Province, and is ventilated and dried in the shade. After screening (through a 2mm sieve) to remove stones and other impurities, it is stored in the dark and sealed.

[0086] The soil remediation conditioner obtained by the examples and comparative examples is added into the soil sample respectively, in order to show the experimental effect, the adding amount of all the soil remediation conditioner of examples and comparative examples is 1% of the mass of the soil, each part of the soil remediation conditioner is added into the corresponding part of the experimental soil, the soil remediation conditioner is mixed uniformly after being applied, then water is added and mixed, the mass ratio of the soil to water is 10:1, the curing treatment is carried out for 60 days (curing conditions: humidity control at 60-80%, temperature control at 25±2℃ during the day and 18±2℃ at night, soil turning 1-2 times per day), and the result test is carried out, 5 parallel experiments are set in each group of experiments, wherein the average value ± standard deviation of 3 experiments in each group is used to represent the results of pH value, soil water-soluble salt content and soil organic matter content; the remaining two groups are used for the determination of particle size composition and petroleum hydrocarbon content.

[0087] Characterization means:

[0088] The determination of various soil physical and chemical property indexes refers to Soil Agricultural Chemistry Analysis.

[0089] 1. Particle size composition: the soil is determined by using a laser particle size analyzer;

[0090] 2. pH value: determined by using a pH meter potential method;

[0091] 3. Soil water-soluble salt content: determined by using a residue drying-mass method;

[0092] 4. Soil organic matter content: determined by using a potassium dichromate oxidation method;

[0093] 5. Petroleum hydrocarbon content: refers to standard HJ1021-2019, determination of petroleum hydrocarbon in soil and sediment by gas chromatography.

[0094] Table 1: Test results of soil remediation conditioner

[0095]

[0096]

[0097] From the experimental results in Table 1, it can be known that the soil remediation conditioner prepared in the application can reduce the pH of saline-alkali soil, the soil remediation conditioner prepared in the application has an adsorption effect on the organic matter in the soil, mitigates the mineralization of the organic matter in the soil, is conducive to maintaining and increasing the soil fertility, increases the organic matter content in the soil, reduces the water-soluble salt content in the soil, the addition of the soil remediation conditioner affects the microbial community structure and abundance in the soil, promotes the biodegradation of organic pollutants in the soil, and reduces the content of organic pollutants in the soil.

[0098] The soil remediation conditioner prepared by the application has small particle size and low bulk density, can improve soil structure, and makes soil texture fine, improves soil porosity and particle arrangement.

[0099] It can be seen from Comparative Examples 1-3 that the steps of treating the biochar with hydrogen peroxide, loading nano-iron on the biochar, and wrapping the outer layer with a solubilizer in the preparation method of the application have great effects on soil improvement and remediation.

[0100] It can be seen from the data analysis of Example 4 and Examples 1-3 that the selection of biochar raw materials has a great influence on soil improvement and remediation. It is found through experiments that the biochar obtained by compounding corn stalks, rice straw and wood chips in a certain ratio has obvious improvement and remediation effects on saline-alkali soil.

[0101] It can be seen from the data analysis of Examples 5-7 that the modification of nano-iron biochar with chitosan is beneficial to the improvement and remediation of saline-alkali soil.

[0102] Each of the embodiments in the specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other. Each embodiment mainly describes the difference from other embodiments. Especially, the system embodiment is basically similar to the method embodiment, so the description is relatively simple, and the related parts can be referred to the part of the method embodiment.

[0103] The above only describes the embodiments of the application and is not used to limit the application. The application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application shall be included in the scope of the claims of the application.

Claims

1. A method for preparing a soil remediation conditioner, characterized in that: The steps include: (1) The biochar was placed in a hydrogen peroxide solution and stirred, then washed with deionized water and dried; (2) soaking the dried biochar in a ferric nitrate solution, filtering it, and transferring it to a tubular furnace filled with inert gas for calcination to obtain nano-iron-loaded biochar; (3) The solubilizer solution and the nano-iron-loaded biochar suspension are evenly mixed and then spray-dried, so that the solubilizer is evenly distributed on the surface of the nano-iron-loaded biochar to obtain a soil remediation conditioner.

2. The preparation method according to claim 1, wherein: In step (1), the concentration of the hydrogen peroxide solution is 10-20%; the mass volume ratio of the biochar to the hydrogen peroxide solution is 1:(20-40).

3. The preparation method according to claim 1, wherein: In step (2), the concentration of the ferric nitrate solution is 10-20%, and the mass ratio of biochar to ferric nitrate is 1:(0.5-1).

4. The preparation method according to claim 1, wherein: The calcination conditions of step (2) are as follows: calcination temperature is 700-800° C., calcination time is 1-3 h, and heating rate is 5-9° C. / min.

5. The preparation method according to claim 1, wherein: The solubilizing agent in step (3) comprises one or more combinations of lauryl polyoxyethylene ether, Tween 80, and sodium lauryl sulfonate; The mass ratio of the solubilizer to the nano-iron loaded biochar is 1%-10%.

6. The preparation method according to claim 1, wherein: The surface of the nano-iron-loaded biochar obtained in step (2) is further loaded with chitosan, and the steps are as follows: adding the nano-iron-loaded biochar powder to the chitosan solution and stirring, then adding a cross-linking agent and stirring, adjusting the pH of the reaction system to 7-9 for reaction, filtering, washing with deionized water, and drying to obtain the product.

7. The preparation method according to claim 6, characterized in that: Chitosan is dissolved in acetic acid solution with a concentration of 1-3% to obtain a 2-5% chitosan solution, and the mass ratio of chitosan to biochar loaded with nano-iron is 1:(3-6).

8. The preparation method according to claim 6, characterized in that: The cross-linking agent is glutaraldehyde or sodium tripolyphosphate, and the cross-linking agent accounts for 20-40% of the mass of the chitosan.

9. The preparation method according to claim 1, wherein: The biochar raw material is selected from one or more of corn straw, soybean straw, rice straw, sunflower straw, wood chips and bamboo; the particle size of the biochar is 50-200 meshes.

10. The soil remediation conditioner prepared by the preparation method according to any one of claims 1 to 9, characterized in that: It is applied to the treatment of saline-alkali soil, with an addition amount of 0.1-10wt%.

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