An environment-friendly soil remediation composition and a preparation method thereof

Abstract

The application relates to the technical field of soil remediation, and particularly discloses an environment-friendly soil remediation composition and a preparation method thereof. The environment-friendly soil remediation composition is prepared from the following raw materials in parts by mass: calcined mineral matrix 25-45 parts, biochar 10-20 parts, humic acid 5-10 parts, potassium-mineral-source fulvic acid 3-8 parts, pre-fermented substance 10-20 parts, wood residue 5-10 parts, pine scale 3-6 parts, attapulgite or / and bentonite 3-8 parts; the calcined mineral matrix is specifically prepared by mixing diatomite and shale and then performing calcination treatment; and the pre-fermented substance is prepared by taking residue of bacteria, traditional Chinese medicine residue and cottonseed meal as raw materials, mixing the raw materials, adding water and a compound bacterial agent, and then performing fermentation. The environment-friendly soil remediation composition prepared by the application has good remediation capacity for divalent heavy metal ions in soil.

Description

Technical Field

[0001] This application relates to the technical field of soil remediation, and more specifically, to an environmentally friendly soil remediation composition and its preparation method. Background Technology

[0002] Among existing remediation technologies, physical remediation is costly, chemical remediation is prone to secondary pollution, and bioremediation often takes too long, making it difficult to meet the comprehensive needs of practical applications.

[0003] Currently, traditional soil remediation agents still have many limitations in practical applications. For common compound-contaminated soils (such as those containing Cd),... 2+ Pb 2+ Cu 2+ Zn 2+ The challenges of remediation are particularly prominent when dealing with multiple heavy metal ions, such as EDTA and EDTA. First, the adsorption capacity of a single adsorbent for heavy metals is limited, and the selectivity for different types of heavy metals is poor, making it difficult to achieve broad-spectrum and efficient fixation. Second, after adsorption, heavy metals are easily desorbed due to fluctuations in environmental pH, which may lead to the risk of secondary release. Furthermore, although some potent chemical chelating agents (such as EDTA) can integrate multiple heavy metals, they are highly biotoxic and difficult to degrade, and long-term use will damage the soil microbial community and ecological balance.

[0004] Patent application CN109913230A discloses a composition for remediation of heavy metal contaminated soil, the composition comprising the following components in parts by weight: 1-4 parts hydroxypropyl methylcellulose; 20-40 parts lignin carbonization; 3-6 parts soybean meal; 5-10 parts diatomaceous earth; 0.1-0.2 parts urease; and 0.1-0.3 parts Bacillus subtilis.

[0005] This technical solution introduces lignin carbonization and diatomaceous earth as mineral carriers, supplemented with soybean meal to provide organic matter and microbial nutrition. Simultaneously, it utilizes the biological action of Bacillus subtilis to achieve, to a certain extent, the adsorption of cadmium in cadmium-contaminated soil. However, its core adsorption material, lignin carbonization, is obtained by pyrolysis and carbonization of lignin at 300-400℃. Within this temperature range, the carbonization has a limited specific surface area and underdeveloped pore structure, resulting in a limited adsorption capacity for cadmium. Summary of the Invention

[0006] To overcome the limitation of limited adsorption capacity in existing soil remediation technologies, this application provides an environmentally friendly soil remediation composition and its preparation method.

[0007] In a first aspect, this application provides an environmentally friendly soil remediation composition, which adopts the following technical solution:

[0008] An environmentally friendly soil remediation composition is prepared from the following raw materials in parts by weight:

[0009] 25-45 parts of calcined mineral matrix, 10-20 parts of biochar, 5-10 parts of humic acid, 3-8 parts of mineral-derived potassium fulvate, 10-20 parts of pre-fermented material, 5-10 parts of wood chips, 3-6 parts of pine bark, and 3-8 parts of attapulgite and / or bentonite.

[0010] The calcined mineral matrix is ​​specifically a mixture of diatomaceous earth and shale, followed by calcination.

[0011] The pre-fermented material is prepared by mixing bacterial residue, Chinese medicine residue and cottonseed meal, adding water and compound bacterial agent, and then fermenting.

[0012] In this technical solution, targeting soil contaminated with divalent cation heavy metals, a stable and high-capacity porous adsorption framework is first constructed by calcining a mineral matrix and biochar to adsorb Cd. 2+ Pb 2+ Cu 2+ Zn 2+ The process achieves efficient physical retention of heavy metal ions. Secondly, it utilizes the abundant functional groups of humic acid and mineral-derived potassium fulvate for chemical chelation, transforming them into stable forms. Simultaneously, an active carrier is prepared through co-fermentation of fungal residue, traditional Chinese medicine residue, and cottonseed meal, introducing functional microorganisms to enhance biological fixation and activate soil ecology. Furthermore, wood chips and pine bark are used to regulate soil physical structure, while the significant ion exchange and adsorption capacity of specially selected attapulgite and / or bentonite directly participates in the auxiliary passivation process.

[0013] Preferably, the mass ratio of diatomite to shale is (1.5~2):1.

[0014] Preferably, the method for preparing the calcined mineral matrix includes the following steps: mixing diatomite and shale evenly, first heating to 150~200℃, holding at that temperature for 50~70min, then heating to 500~550℃, calcining for 2~3h, and cooling to obtain the calcined mineral matrix.

[0015] In this technical solution, the gradient calcination process can effectively remove bound water and impurities, ensuring the porous framework of minerals, increasing specific surface area and activating the surface, thus laying the foundation for efficient physical adsorption.

[0016] Preferably, the method for preparing the pre-fermented product includes the following steps:

[0017] Mix the bacterial residue, Chinese medicine residue, and cottonseed meal evenly, adjust the moisture content to 50%~60%, add compound bacterial agent, and incubate at 30~35℃ for 5~7 days. Then, ferment at 50~55℃ for 10~12 days, and dry to obtain the pre-fermented product.

[0018] Preferably, the compound microbial agent includes Bacillus subtilis and Pseudomonas.

[0019] Preferably, the amount of the compound microbial agent used is 0.5% to 2% of the total mass of the microbial residue, medicinal herb residue and cottonseed meal.

[0020] In this technical solution, a segmented fermentation process is adopted, which not only matches the optimal activity temperature of Bacillus subtilis and Pseudomonas aeruginosa, ensuring the enrichment of functional microbial communities, but also completes the decomposition of organic waste, realizing the core functions of bioremediation and ecological activation.

[0021] Preferably, the mass ratio of the fungal residue, medicinal residue and cottonseed meal is (10~20):(7~16):(3~9).

[0022] More preferably, the calcined mineral matrix undergoes the following modification treatment before use:

[0023] After acidification treatment, the calcined mineral matrix is ​​immersed in a solution containing phosphate and mixed for 3-5 hours. After solid-liquid separation and drying, it is kept at 240-280℃ for 110-130 minutes under an inert atmosphere and then cooled to obtain the modified calcined mineral matrix.

[0024] Preferably, the acidification treatment specifically involves: immersing the calcined mineral matrix in a 1%~2% hydrochloric acid solution, mixing for 1.5~2.5 hours, separating the solid and liquid, washing, drying, and storing for later use.

[0025] Preferably, the phosphate-containing solution is an ammonium dihydrogen phosphate solution.

[0026] Preferably, the molar concentration of the ammonium dihydrogen phosphate solution is 0.5~1 mol / L.

[0027] In this technical solution, surface hydroxyl groups are activated by acidification pretreatment, and then phosphate loading under an inert atmosphere is combined to form a dual mechanism of physical retention and chemical precipitation for fixation.

[0028] More preferably, the environmentally friendly soil remediation composition further includes 1-3 parts by weight of polyglutamic acid.

[0029] In this technical solution, polyglutamic acid can bind with free heavy metal ions in soil solution to form stable macromolecular complexes, which can rapidly reduce the immediate bioavailability and migration risk of heavy metals.

[0030] More preferably, the environmentally friendly soil remediation composition further includes 4-6 parts by weight of carboxymethyl chitosan.

[0031] In this technical solution, the unique amino and carboxyl bifunctional structure of carboxymethyl chitosan gives it stronger pH adaptability and higher selectivity in chelating heavy metals.

[0032] Secondly, this application provides a method for preparing an environmentally friendly soil remediation composition, comprising the following steps:

[0033] Calcined mineral matrix, biochar, humic acid, mineral-derived potassium humate, pre-fermented material, wood chips, pine bark, attapulgite and / or bentonite are added to a mixer and mixed evenly to obtain an environmentally friendly soil remediation composition.

[0034] In this technical solution, the method uses material pretreatment and physical mixing processes to uniformly combine the components in a dry state, thereby preparing a repair composition powder with uniform components and stable performance.

[0035] Preferably, the method for adding the polyglutamic acid is as follows: the polyglutamic acid is prepared into an aqueous solution, sprayed onto the surface of the biochar, and then dried.

[0036] Preferably, the method for adding the carboxymethyl chitosan is to premix the carboxymethyl chitosan with humic acid.

[0037] In this technical solution, considering the characteristics of polyglutamic acid being highly water-soluble and hygroscopic, and carboxymethyl chitosan being prone to flocculation, pretreatment schemes were designed, namely, aqueous solution spray coating of biochar and premixing and dispersing with humic acid. These schemes not only ensure the uniform dispersion of polymer components in dry powder, but also improve the storage stability of the product, while maximizing its function of chelating / complexing heavy metals.

[0038] In summary, this application has the following beneficial effects:

[0039] This application employs a combination of calcined mineral matrix and biochar to construct a composite adsorption framework with more developed pores and a higher specific surface area, significantly enhancing the adsorption capacity for Cd. 2+ Pb 2+ The physical retention capacity of heavy metal ions is measured. Simultaneously, humic acid and mineral-derived potassium fulvate provide chemical chelation capabilities, while the pre-fermented material introduces biological fixation and ecological regulation functions, thus forming a synergistic remediation system. Detailed Implementation

[0040] The present application will be further described in detail below with reference to the embodiments.

[0041] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0042] In the following embodiments,

[0043] Before using diatomaceous earth, it should be crushed and passed through a 100-mesh standard sieve. The material passing through the sieve should be taken, and then passed through a 200-mesh standard sieve. The material remaining on the sieve should be taken for later use.

[0044] Before using shale, it should be crushed and passed through a 100-mesh standard sieve. The material passing through the sieve should be taken, and then passed through a 200-mesh standard sieve. The material remaining on the sieve should be taken for later use.

[0045] Before using the mushroom residue, it should be crushed and passed through a 20-mesh standard sieve. The material passing through the sieve should be collected and set aside for later use.

[0046] Before using Chinese medicine residue, it should be crushed and passed through a 20-mesh standard sieve. The material passing through the sieve should be collected and set aside for later use.

[0047] Before using cottonseed meal, it should be crushed and passed through a 20-mesh standard sieve. The material passing through the sieve should be collected and kept for later use.

[0048] Preparation Examples 1-2: Calcinated Mineral Matrix

[0049] Preparation Example 1

[0050] The preparation method of the calcined mineral matrix in this example includes the following steps:

[0051] Diatomaceous earth and shale were added to a mixer at a mass ratio of 2:1 and mixed at 300 rpm for 30 min. The mixture was then transferred to a sintering furnace and heated to 150°C at a rate of 3°C / min. The temperature was held for 70 min, and then further increased to 500°C. The mixture was then calcined for 3 h and cooled to room temperature with the furnace to obtain the calcined mineral matrix.

[0052] Preparation Example 2

[0053] The preparation method of the calcined mineral matrix in this example includes the following steps:

[0054] Diatomaceous earth and shale were added to a mixer at a mass ratio of 1.5:1 and mixed at 300 rpm for 30 min. The mixture was then transferred to a sintering furnace and heated to 200°C at a rate of 3°C / min. The temperature was held for 50 min, and then further increased to 550°C. The mixture was then calcined for 2 h and cooled to room temperature with the furnace to obtain the calcined mineral matrix.

[0055] Preparation Examples 3-4: Modified Calcined Mineral Matrix

[0056] Preparation Example 3

[0057] The preparation method of the modified calcined mineral matrix in this example includes the following steps:

[0058] The calcined mineral matrix from Preparation Example 1 was immersed in a 1% hydrochloric acid solution with a solid-liquid ratio of 1g:5mL, stirred and mixed at 25°C for 2.5h, washed with deionized water until neutral, dried at 50°C for 2h, and then immersed in a 0.5mol / L ammonium dihydrogen phosphate solution with a solid-liquid ratio of 1g:5mL, stirred and mixed at 25°C for 5h, filtered, rinsed twice with deionized water, dried at 60°C for 3h, heated to 280°C at a rate of 3°C / min under nitrogen protection, held at 280°C for 110min, and cooled to room temperature with the furnace to obtain the modified calcined mineral matrix.

[0059] Preparation Example 4

[0060] The preparation method of the modified calcined mineral matrix in this example includes the following steps:

[0061] The calcined mineral matrix from Preparation Example 1 was immersed in a 2% hydrochloric acid solution with a solid-liquid ratio of 1g:5mL, stirred and mixed at 25°C for 1.5h, washed with deionized water until neutral, dried at 50°C for 2h, and then immersed in a 1mol / L ammonium dihydrogen phosphate solution with a solid-liquid ratio of 1g:5mL, stirred and mixed at 25°C for 4h, filtered, rinsed twice with deionized water, dried at 60°C for 3h, heated to 240°C at a rate of 3°C / min under nitrogen protection, held at that temperature for 130min, and cooled to room temperature with the furnace to obtain the modified calcined mineral matrix.

[0062] Preparation of pre-fermented products in Examples 5-7

[0063] Preparation Example 5

[0064] The preparation method of the pre-fermented product in this example includes the following steps:

[0065] Mix the mushroom residue, medicinal herb residue, and cottonseed meal in a mass ratio of 10:7:3 evenly, then spray with deionized water to adjust the moisture content to 50%. Add 0.5% of the total mass of the mushroom residue, medicinal herb residue, and cottonseed meal as a compound microbial agent, stir evenly, and transfer to a constant temperature fermentation device. Seal and ferment at 30℃ for 7 days, then raise the temperature to 50℃ and ferment for 12 days. Dry at 50℃ until the moisture content is about 10%, crush, and sieve to obtain the pre-fermented material.

[0066] In the compound microbial agent, the mass ratio of Bacillus subtilis to Pseudomonas is 1:1.

[0067] Preparation Example 6

[0068] The preparation method of the pre-fermented product in this example includes the following steps:

[0069] Mix the mushroom residue, medicinal herb residue, and cottonseed meal in a mass ratio of 20:16:9 evenly, then spray with deionized water to adjust the moisture content to 60%. Add 2% of the compound microbial agent (based on the total mass of the mushroom residue, medicinal herb residue, and cottonseed meal), mix well, and transfer to a constant temperature fermentation device. Seal and ferment at 35℃ for 5 days, then raise the temperature to 55℃ and allow it to mature for 10 days. Dry at 50℃ until the moisture content is about 10%, then crush and sieve to obtain the pre-fermented material.

[0070] In the compound microbial agent, the mass ratio of Bacillus subtilis to Pseudomonas aeruginosa is 2:1.

[0071] Preparation Example 7

[0072] The preparation method of the pre-fermented product in this example includes the following steps:

[0073] Mix the mushroom residue, medicinal herb residue, and cottonseed meal in a mass ratio of 15:12:6 evenly, then spray with deionized water to adjust the moisture content to 60%. Add 2% of the compound microbial agent (based on the total mass of the mushroom residue, medicinal herb residue, and cottonseed meal), mix well, and transfer to a constant temperature fermentation device. Seal and ferment at 35℃ for 5 days, then raise the temperature to 55℃ and allow it to mature for 10 days. Dry at 50℃ until the moisture content is about 10%, then crush and sieve to obtain the pre-fermented material.

[0074] In the compound microbial agent, the mass ratio of Bacillus subtilis to Pseudomonas is 1:2.

[0075] Example 1

[0076] The preparation method of the environmentally friendly soil remediation composition in this embodiment includes the following steps:

[0077] Add 2.5 kg of calcined mineral matrix, 1 kg of biochar, 0.5 kg of humic acid, 0.3 kg of mineral-derived potassium fulvate, 1 kg of pre-fermented material, 0.5 kg of wood chips, 0.3 kg of pine bark, and 0.3 kg of attapulgite to a mixer and mix at 400 rpm for 15 minutes to obtain an environmentally friendly soil remediation composition.

[0078] The calcined mineral matrix was derived from Preparation Example 1; the pre-fermented product was derived from Preparation Example 5.

[0079] Example 2

[0080] The preparation method of the environmentally friendly soil remediation composition in this embodiment includes the following steps:

[0081] Add 4.5 kg of calcined mineral matrix, 2 kg of biochar, 1 kg of humic acid, 0.8 kg of mineral-derived potassium fulvate, 2 kg of pre-fermented material, 1 kg of wood chips, 0.6 kg of pine bark, 0.3 kg of attapulgite, and 0.5 kg of bentonite to a mixer and mix at 400 rpm for 30 minutes to obtain an environmentally friendly soil remediation composition.

[0082] The calcined mineral matrix was derived from Preparation Example 2; the pre-fermented product was derived from Preparation Example 6.

[0083] Example 3

[0084] The preparation method of the environmentally friendly soil remediation composition in this embodiment includes the following steps:

[0085] Add 3.0 kg of calcined mineral matrix, 1.5 kg of biochar, 0.8 kg of humic acid, 0.5 kg of mineral-derived potassium fulvate, 1.6 kg of pre-fermented material, 0.8 kg of wood chips, 0.5 kg of pine bark, 0.3 kg of attapulgite, and 0.3 kg of bentonite to a mixer and mix at 400 rpm for 25 minutes to obtain an environmentally friendly soil remediation composition.

[0086] The calcined mineral matrix was derived from Preparation Example 2; the pre-fermented product was derived from Preparation Example 7.

[0087] Example 4

[0088] The difference between this embodiment and embodiment 3 is as follows:

[0089] The calcined mineral matrix was derived from Preparation Example 3;

[0090] Everything else is the same as in Example 3.

[0091] Example 5

[0092] The preparation method of the environmentally friendly soil remediation composition in this embodiment includes the following steps:

[0093] Add 3.0 kg of calcined mineral matrix, 1.5 kg of biochar, 0.8 kg of humic acid, 0.5 kg of mineral-derived potassium fulvate, 1.6 kg of pre-fermented material, 0.8 kg of wood chips, 0.5 kg of pine bark, 0.3 kg of attapulgite, and 0.3 kg of bentonite to a mixer and mix at 400 rpm for 25 minutes to obtain an environmentally friendly soil remediation composition.

[0094] The environmentally friendly soil remediation composition of this embodiment also includes 0.1 kg of polyglutamic acid;

[0095] The method for adding polyglutamic acid is as follows:

[0096] Mix 0.1 kg of polyglutamic acid and 0.9 kg of deionized water evenly, spray the mixture onto the surface of 1.5 kg of biochar, dry it at 45°C with forced air until the moisture content is about 8%, and then add the mixture.

[0097] The calcined mineral matrix was derived from Preparation Example 3; the pre-fermented product was derived from Preparation Example 7.

[0098] Example 6

[0099] The preparation method of the environmentally friendly soil remediation composition in this embodiment includes the following steps:

[0100] Add 3.0 kg of calcined mineral matrix, 1.5 kg of biochar, 0.8 kg of humic acid, 0.5 kg of mineral-derived potassium fulvate, 1.6 kg of pre-fermented material, 0.8 kg of wood chips, 0.5 kg of pine bark, 0.3 kg of attapulgite, and 0.3 kg of bentonite to a mixer and mix at 400 rpm for 25 minutes to obtain an environmentally friendly soil remediation composition.

[0101] The environmentally friendly soil remediation composition of this embodiment also includes 0.3 kg of polyglutamic acid;

[0102] The method for adding polyglutamic acid is as follows: Mix 0.3 kg of polyglutamic acid and 0.7 kg of deionized water evenly, spray the mixture onto the surface of 1.5 kg of biochar, dry it at 45°C with forced air until the moisture content is about 8%, and then add it.

[0103] The calcined mineral matrix was derived from Preparation Example 4; the pre-fermented product was derived from Preparation Example 7.

[0104] Example 7

[0105] The preparation method of the environmentally friendly soil remediation composition in this embodiment includes the following steps:

[0106] Add 3.0 kg of calcined mineral matrix, 1.5 kg of biochar, 0.8 kg of humic acid, 0.5 kg of mineral-derived potassium fulvate, 1.6 kg of pre-fermented material, 0.8 kg of wood chips, 0.5 kg of pine bark, 0.3 kg of attapulgite, and 0.3 kg of bentonite to a mixer and mix at 400 rpm for 25 minutes to obtain an environmentally friendly soil remediation composition.

[0107] The environmentally friendly soil remediation composition of this embodiment also includes 0.1 kg of polyglutamic acid and 0.4 kg of carboxymethyl chitosan;

[0108] The method for adding polyglutamic acid is as follows: Mix 0.1 kg of polyglutamic acid and 0.9 kg of deionized water evenly, spray the mixture onto the surface of 1.5 kg of biochar, dry it at 45°C with forced air until the moisture content is about 8%, and then add the mixture.

[0109] The method for adding carboxymethyl chitosan is as follows: mix 0.8 kg of humic acid and 0.4 kg of carboxymethyl chitosan evenly and then add them;

[0110] The calcined mineral matrix was derived from Preparation Example 4; the pre-fermented product was derived from Preparation Example 7.

[0111] Example 8

[0112] The preparation method of the environmentally friendly soil remediation composition in this embodiment includes the following steps:

[0113] Add 3.0 kg of calcined mineral matrix, 1.5 kg of biochar, 0.8 kg of humic acid, 0.5 kg of mineral-derived potassium fulvate, 1.6 kg of pre-fermented material, 0.8 kg of wood chips, 0.5 kg of pine bark, 0.6 kg of carboxymethyl chitosan, 0.3 kg of attapulgite, and 0.3 kg of bentonite to a mixer and mix at 400 rpm for 25 minutes to obtain an environmentally friendly soil remediation composition.

[0114] The environmentally friendly soil remediation composition of this embodiment also includes 0.6 kg of carboxymethyl chitosan;

[0115] The method for adding carboxymethyl chitosan is as follows: mix 0.8 kg of humic acid and 0.6 kg of carboxymethyl chitosan evenly and then add them;

[0116] The calcined mineral matrix was derived from Preparation Example 4; the pre-fermented product was derived from Preparation Example 7.

[0117] Comparative Example 1

[0118] The difference between this comparative example and Example 1 is as follows:

[0119] No biochar was added;

[0120] Everything else is the same as in Example 1.

[0121] Comparative Example 2

[0122] The difference between this comparative example and Example 1 is as follows:

[0123] No humic acid was added;

[0124] Everything else is the same as in Example 1.

[0125] Comparative Example 3

[0126] The difference between this comparative example and Example 1 is as follows:

[0127] Replace the pre-fermented material with a premix of equal quality;

[0128] The method for preparing the premix includes the following steps:

[0129] After mixing the fungal residue, medicinal herb residue and cottonseed meal in a mass ratio of 10:7:3 evenly, deionized water is sprayed on the mixture to adjust the moisture content to about 10%, thus obtaining a premix.

[0130] Everything else is the same as in Example 1.

[0131] Comparative Example 4

[0132] The difference between this comparative example and Example 1 is as follows:

[0133] The preparation method of the calcined mineral matrix in this example includes the following steps:

[0134] Diatomaceous earth was placed in a sintering furnace and heated to 150°C at a rate of 3°C / min. The temperature was held for 70 min, then further heated to 500°C and held for calcination for 3 h. The furnace was then cooled to room temperature to obtain the calcined mineral matrix.

[0135] Everything else is the same as in Example 1.

[0136] Performance testing

[0137] Soil samples were collected from contaminated farmland surrounding a mining area. After removing plant and animal remains and other debris, the soil was air-dried, pulverized, and sieved through a 20-mesh sieve. The sieved soil was then thoroughly mixed and used as the test soil. The basic properties and heavy metal content of the soil were tested according to GB 15618-2018. Its basic physicochemical properties and pollution status are as follows: pH value 5.8, organic matter content 13.6 g / kg, Cd... 2+ Content 2.5 mg / kg, Pb 2+ Content 323mg / kg, Cu 2+ Content 125mg / kg, Zn 2+ Content 370mg / kg.

[0138] The above-mentioned test soil was divided into several portions, and 2.0 kg (dry weight) of each portion was weighed and placed in a plastic basin. 20 g of the environmentally friendly soil remediation composition prepared in Examples 1-8 and Comparative Examples 1-4 was added to each basin of soil. The soil was thoroughly mixed with the soil, and the soil moisture content was adjusted to 60% of the field water holding capacity. The soil was then placed in a greenhouse for stable cultivation for 90 days before sampling.

[0139] The collected soil samples were divided into two parts: one part was air-dried and used to determine the soil pH and organic matter content; the other part, a fresh sample, was sieved and the available Cd was determined using an extraction method. 2+ Pb 2+ Cu 2+ Zn 2+ The content of [specific element] was determined, and the passivation rate was calculated; see Table 1 for details.

[0140] Table 1. Performance characterization of the environmentally friendly soil remediation compositions prepared in Examples 1-8 and Comparative Examples 1-4

[0141]

[0142] Analysis of Examples 1-3 shows that the optimization of the basic formula results in a synergistic improvement in both the heavy metal passivation effect and soil improvement indicators, demonstrating that the composition has a comprehensive remediation capability of simultaneously passivating multiple heavy metals, regulating soil pH, and increasing organic matter content.

[0143] Analysis of Examples 1 and Comparative Examples 1-4 shows that the absence of any component—biochar, humic acid, pre-fermentation process, or composite mineral matrix—significantly reduces the passivation effect and soil improvement indicators. Comparative Example 3 (without pre-fermentation) exhibited poor overall performance, indicating that the pre-fermentation process not only enriches functional microbial communities to achieve heavy metal bio-fixation and generates active chelate functional groups to enhance chemical retention, but also ensures benign improvement of the soil ecology, serving as a core prerequisite for activating organic functional matrices. Comparative Example 1 (without biochar) showed a balanced decrease in the passivation rate of each heavy metal, with a slight decrease in soil organic matter, demonstrating the crucial supporting role of biochar as a high specific surface area adsorption carrier in the physical retention of heavy metals and the improvement of soil pore structure. Comparative Example 2 (without humic acid) showed only a slight decrease in passivation rate, with only Cu showing a slight decrease. 2+ Zn 2+ The slightly larger decrease highlights the effect of humic acid on Cu. 2+ Zn 2+ The specific chelating ability of humic acid, and the fact that its soil organic matter is still close to that of Example 1, confirms that the core value of humic acid lies in functional group complexation rather than simply supplementing organic matter; the passivation effect of Comparative Example 4 (calcined diatomaceous earth alone) is inferior to that of the composite mineral matrix, although its Pb 2+ Because the basic adsorption of diatomaceous earth retains a certain passivation rate, but the overall performance is still not as good as the composite calcination system in Example 1, it indicates that the synergistic calcination of diatomaceous earth and shale can form a more developed multi-level pore structure, enhance the physical retention and surface activity of the mineral matrix, and improve the overall passivation performance.

[0144] Analysis of Examples 3-8 shows that the passivation rate is significantly improved after using a modified calcined mineral matrix, especially for Cd. 2 + Pb 2+ The passivation improvement was the greatest; the addition of polyglutamic acid and / or carboxymethyl chitosan further enhanced the passivation of Cd. 2+ Pb 2+ The fixing effect, while also affecting Cu 2+ Zn 2+ The passivation effect has also been significantly improved.

[0145] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An environmentally friendly soil remediation composition, characterized in that, It is prepared from the following raw materials in parts by weight: 25-45 parts of calcined mineral matrix, 10-20 parts of biochar, 5-10 parts of humic acid, 3-8 parts of mineral-derived potassium fulvate, 10-20 parts of pre-fermented material, 5-10 parts of wood chips, 3-6 parts of pine bark, and 3-8 parts of attapulgite and / or bentonite. The calcined mineral matrix is ​​specifically a mixture of diatomaceous earth and shale, followed by calcination. The preparation method of calcined mineral matrix includes the following steps: after mixing diatomite and shale evenly, first heat to 150~200℃, keep at the temperature for 50~70min, then heat to 500~550℃, calcinate for 2~3h, cool, and obtain calcined mineral matrix; Before use, the calcined mineral matrix undergoes the following modification treatment: after acidification, the calcined mineral matrix is ​​immersed in a solution containing phosphate, mixed for 3-5 hours, separated from the solid, dried, and then kept at 240-280℃ for 110-130 minutes under an inert atmosphere and cooled to obtain the modified calcined mineral matrix. The pre-fermented material is prepared by mixing bacterial residue, Chinese medicine residue and cottonseed meal, adding water and compound bacterial agent, and then fermenting. The environmentally friendly soil remediation composition also includes 1-3 parts by weight of polyglutamic acid and 4-6 parts by weight of carboxymethyl chitosan.

2. The environmentally friendly soil remediation composition according to claim 1, characterized in that, The method for preparing the pre-fermented product includes the following steps: Mix the bacterial residue, Chinese medicine residue, and cottonseed meal evenly, adjust the moisture content to 50%~60%, add compound bacterial agent, and incubate at 30~35℃ for 5~7 days. Then, ferment at 50~55℃ for 10~12 days, and dry to obtain the pre-fermented product.

3. The environmentally friendly soil remediation composition according to claim 2, characterized in that, The mass ratio of the fungal residue, medicinal herb residue and cottonseed meal is (10~20):(7~16):(3~9).

4. A method for preparing an environmentally friendly soil remediation composition as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Calcined mineral matrix, biochar, humic acid, mineral-derived potassium fulvate, pre-fermented material, wood chips, pine bark, attapulgite and / or bentonite are added to a mixer and mixed evenly to obtain an environmentally friendly soil remediation composition. The method for adding polyglutamic acid is as follows: the polyglutamic acid is prepared into an aqueous solution, sprayed onto the surface of biochar, and then dried; The method for adding carboxymethyl chitosan is as follows: premix carboxymethyl chitosan with humic acid.

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