Preparation method and application of mineral ecological base repair material based on LDHs (layered double hydroxides) coating

Abstract

The invention belongs to the crossing field of environmental functional materials and microbial technologies, and particularly relates to a preparation method of a mineral ecological base repair material based on an LDHs (layered double hydroxides) coating, which comprises the following steps: S1, pretreatment of a matrix material; s2, preparing an LDHs modified matrix with active or passive biological membrane loading capacity; s3, whether the target functional bacteria are loaded or not is selected according to the repair requirement, and if yes, the biological enhancement functional repair material is prepared; and if the LDHs modified matrix is not loaded, directly taking the LDHs modified matrix as a universal mineral ecological base repairing material. According to the preparation method disclosed by the invention, based on the structure adjustability of the LDHs material, the targeted adsorption efficiency and the biofilm carrier performance of the material are remarkably improved by accurately designing key parameters such as metal ion combination, proportion and intercalation ions; meanwhile, a porous matrix structure is optimized, a biological-abiotic synergistic remediation mechanism is strengthened, and the method has the advantages of low cost, good ecological compatibility, strong scene adaptability, good remediation effect and the like.

Description

A method for preparing and applying mineral-based ecological remediation materials based on LDH coatings. Technical Field

[0001] This invention belongs to the interdisciplinary field of environmental functional materials and microbial technology, specifically involving a method for preparing and applying a mineral ecological base remediation material based on LDHs coating. Background Technology

[0002] LDHs are synthetically produced anionic clay minerals with a layered structure, consisting of positively charged host layers, negatively charged interlayer anions, and partial water of crystallization. Compared to natural clay minerals, the structure and composition of LDHs are artificially adjustable: the types and proportions of metal cations and the types of interlayer anions can be controlled according to requirements. By precisely controlling the raw material ratios and hydrothermal conditions during the preparation process, functional LDH particles with a rich variety and excellent crystallinity and stability can be prepared. For example, researchers have enhanced the adsorption of phosphates by introducing specific elements (such as Cu, La, and Zr) with strong affinity for phosphorus into LDHs. Other studies have utilized ion exchange methods to... 2- Ions are inserted into the interlayer space of LDHs, leveraging their soft Lewis base properties and interlayer widening effect to construct highly efficient heavy metal ion adsorption materials. Furthermore, LDHs materials exhibit good biocompatibility, serving as microbial immobilization carriers that can significantly enhance microbial enzyme activity, extracellular polymeric substances (EPS) content, and biodiversity, thereby strengthening removal efficiency.

[0003] However, applying particulate LDHs to real-world ecosystem scenarios still faces significant application bottlenecks and potential risks: First, due to the particle's own morphology and the ecological environment (such as water flow and soil infiltration), the material is prone to migration and loss, resulting in both the depletion of remediation agents and a direct decrease in the remediation efficiency of the target area; Second, the nanoparticle structure makes it difficult to efficiently recycle the material after the remediation cycle ends, potentially causing it to remain in the environment for a long time; Third, the aforementioned loss and retention problems, when combined, may also trigger ecological risks (such as potential adverse effects on aquatic organisms and soil microbial communities). These factors collectively restrict the large-scale and safe application of particulate LDHs in the field of ecological restoration. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a mineral ecological base remediation material based on LDHs coating, its preparation method and application, which is used to construct a sediment pollution isolation layer or active reactive infiltration barrier, suitable for the remediation of pollutants in lake bottom sediment, and to achieve efficient and long-term control of endogenous pollution.

[0005] This invention provides a method for preparing a mineral-based ecological remediation material based on LDHs coating, comprising the following steps: S1, Pretreatment of matrix material: Selecting matrix material, washing and drying it sequentially, and setting it aside; S2, Preparation of LDHs modified matrix: Mixing and dissolving divalent and trivalent metal salts to obtain a mixed metal solution, adding the mixed metal solution to the matrix material pretreated in step S1, adjusting the pH of the reaction system, removing excess water from the reaction system, and then carrying out an aging reaction; After the reaction is completed, washing and drying the reaction system sequentially to obtain an LDHs modified matrix with active or passive biofilm loading capacity; S3, Selecting whether to load target functional bacteria according to remediation needs. If target functional bacteria are selected, the concentration of the target functional bacteria is 10. 8 -10 9 With CFU / mL and a liquid-to-solid ratio of 10:1 to 20:1 between the target functional bacteria and the LDHs-modified matrix, a mineral ecological-based remediation material with bio-enhanced functionality is prepared after loading the target functional bacteria. If not loaded, the LDHs-modified matrix can promote in-situ microbial coating and growth based on its own biofilm carrier characteristics and can be directly used as a general-purpose mineral ecological-based remediation material.

[0006] Furthermore, in S1, the matrix material is one or more of quartz sand, basalt, volcanic rock, or ceramsite.

[0007] Furthermore, in S1, the particle size of the matrix material can be one or more, wherein the coarse particle size is 0.5-5 mm and the fine particle size is 0.05-0.5 mm; if the matrix material is a mixture of coarse and fine particle sizes, the mass ratio of coarse particle size to fine particle size is 2:1 to 5:1.

[0008] Furthermore, in S2, both divalent and trivalent metal salts can be one of nitrates, chlorides, and carbonates.

[0009] Furthermore, in S2, the molar ratio of divalent metal cations to trivalent metal cations in both divalent and trivalent metal salts is 1:1 to 1:3, and the divalent metal cation can be Ca. 2+ Mg 2+ Zn 2+ Co 2+ One of the trivalent metal cations is Al. 3+ Fe 3+ One of them.

[0010] Furthermore, in S2, the mass ratio of mixed metal solution to matrix material is 2.5:1 to 10:1, and the total metal ion concentration in the mixed metal solution is preferably 0.5 to 2.0 mol / L.

[0011] Furthermore, in S2, the specific operation for adjusting the pH of the reaction system is as follows: the pH of the reaction system is adjusted to 10±0.2~12±0.2 using an alkaline solution; the temperature conditions for the aging reaction are 65~80℃, and the time conditions are 18 h.

[0012] Furthermore, the alkaline solution is one or both of sodium hydroxide solution and sodium carbonate solution.

[0013] The mineral-based ecological restoration material obtained by the above preparation method.

[0014] The above-mentioned mineral ecological base remediation materials are used in the remediation of pollutants in lake bottom sediments.

[0015] The core of this invention lies in constructing a soil-like granular material with a triple structure of "porous matrix core - LDHs functional coating - biofilm layer". This breaks through the single performance limitations of traditional LDHs materials in adsorption or bioremediation, and achieves the synergy of physical stability, chemical adsorption and biodegradation, thus achieving the dual goals of targeted pollution remediation and micro-ecosystem reconstruction.

[0016] The beneficial effects of the present invention are: (1) The present invention improves the repair efficiency of the material by accurately controlling the pore size and porosity of the interface layer of the repair environment by adapting to the hydraulic load and material exchange requirements of the in-situ repair scenario; (2) The present invention enhances the targeted adsorption capacity of pollutants by using artificially customized LDHs as a functional coating; (3) The LDHs coating of the present invention can also be used as a biofilm carrier to optimize the surface characteristics of the matrix and provide a slow-release nutrient source, thereby strengthening the directional colonization and degradation function of microorganisms; (4) The present invention proposes a scenario-based customization process for LDHs-based mineral-biofilm composite materials to achieve flexible functional design and precise adaptation, overcoming the problems of poor adaptability and low repair efficiency of traditional materials. Figure 1 shows the effect of different mineral-based remediation materials on the phosphate concentration in the overlying water of lake sediment; Figure 2 shows the regulatory effect of different metal LDH coatings on biofilm growth on the surface of quartz sand; Figure 3 shows the TP changes in the overlying water of lake sediment caused by different mineral-based remediation materials; Figure 4 shows the SRP changes in the overlying water of lake sediment caused by different mineral-based remediation materials; Figure 5 shows the SEM and EDS images of MgFe-Cl-LDH@quartz sand before (a, b) and after (c, d) biofilm loading; Figure 6 shows the effect of different treatment groups on the removal efficiency of hydrophobic pollutant BDE-47. Detailed Implementation

[0018] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0019] The first thing this invention aims to protect is a method for preparing a mineral ecological base remediation material, which includes the following steps: S1, Pretreatment of matrix material: Select matrix material, and wash and dry the matrix material in sequence for later use.

[0020] Specifically, based on the different remediation scenarios such as sediments, groundwater, and soil, the physical structure (particle size, porosity, and compressive strength) of the matrix materials is controlled by scientifically selecting matrix materials and using gradient gradation, so as to provide a stable support carrier for subsequent coating loading and biofilm adhesion.

[0021] Ideally, in lake sediment remediation environments, the selected matrix material is one or more of quartz sand, basalt, volcanic rock, or ceramsite, which serves as a structural matrix with high mechanical strength and chemical stability. The particle size of the matrix material can also be one or more, with coarse particles of 0.5-5 mm and fine particles of 0.05-0.5 mm. If the matrix material is a mixture of coarse and fine particles, the mass ratio of coarse to fine particles is 2:1 to 5:1.

[0022] As an embodiment of the present invention, for the construction of a sediment contamination isolation layer, it is recommended that the matrix material have a particle size of 1-5 mm (coarse) and 0.2-0.5 mm (fine) in a mass ratio of 3:1-5:1, so that the porosity is 35-50% and the compressive strength is ≥8MPa; for the active reactive permeability barrier, it is recommended that the matrix material have a particle size of 2-5 mm (coarse) and 0.5-1 mm (fine) in a mass ratio of 2:1-4:1, so that the porosity is 40-55% and the compressive strength is ≥5 MPa.

[0023] S2. Preparation of LDHs modified matrix: After the divalent metal salt and trivalent metal salt are mixed and dissolved evenly, a mixed metal solution is obtained. The mixed metal solution is added to the matrix material pretreated in step S1. The pH of the reaction system is adjusted to 10±0.2~12±0.2 using alkaline solution. Stirring is continued until the water in the reaction system is almost evaporated. The resulting solid-liquid mixture is placed in an oven at 65~80℃ for aging for 18 h. Then it is washed with deionized water until the pH is neutral, and then placed in an oven at 60~70℃ for drying. The LDHs modified matrix with active or passive biofilm loading capacity is thus obtained.

[0024] In this invention, the LDHs modified matrix is ​​prepared by co-precipitation. Both the divalent and trivalent metal salts can be one of nitrates, chlorides, and carbonates. The molar ratio of the divalent metal cation to the trivalent metal cation in the divalent and trivalent metal salts is 1:1 to 1:3, and the divalent metal cation can be Ca... 2+ Mg 2+ Zn 2+ Co 2+ One of the trivalent metal cations is Al.3+ Fe 3+ One of the following can be used: specifically, it can be one of the divalent metal salts calcium chloride, calcium nitrate, calcium carbonate, magnesium chloride, magnesium nitrate, magnesium carbonate, zinc chloride, zinc nitrate, or zinc carbonate; the trivalent metal salt can be one of the following: ferric chloride, ferric nitrate, ferric carbonate, aluminum chloride, aluminum nitrate, or aluminum carbonate; the mass ratio of the mixed metal solution to the matrix material is 2.5:1 to 10:1 to ensure that the solution fully wets all matrix particles. The total metal ion concentration in the mixed metal solution is preferably 0.5 to 2.0 mol / L. The specific concentration needs to be matched with the specific surface area of ​​the matrix to achieve precise control of the coating thickness and loading, avoiding the formation of a large amount of free LDHs due to excessive supersaturation.

[0025] The alkaline solution is one or both of sodium hydroxide solution and sodium carbonate solution.

[0026] In this invention, divalent metal cations (M) commonly found in the natural environment are preferred. 2+ ) and trivalent (M 3+ The metal cations are combined in a specific ratio, and the selected metal cations can serve as cofactors for microbial functional enzymes (such as dehydrogenases and degradative enzymes), laying the foundation for subsequent enhancement of biofilm activity; by directionally adjusting the types of interlayer anions (such as CO32-), 2- NO3 - We precisely optimize the interlayer spacing (expanding mass transfer channels), surface charge (enhancing pollutant adsorption selectivity), and pore structure (increasing adsorption sites) of LDHs materials to ensure that their physicochemical properties are highly compatible with the removal requirements of targeted pollutants.

[0027] S3. Select whether to load target functional bacteria based on the remediation needs. If loading target functional bacteria is selected, and a bio-enhanced functional mineral-based remediation material is prepared, the concentration of the target functional bacteria will be 10. 8 -10 9 The concentration of CFU / mL and the liquid-to-solid ratio of the target functional bacteria to the LDHs modified matrix are 10:1 to 20:1. If not loaded, the LDHs modified matrix can promote in-situ microbial coating and growth based on its own biofilm carrier characteristics, and can be directly used as a general-purpose mineral ecological base remediation material.

[0028] Loading target functional bacteria onto an LDH-modified matrix can improve the remediation rate of pollutants by the LDH-modified matrix. Therefore, in practical applications, the loading of target functional bacteria can be selected according to requirements. The target functional bacteria can be in-situ indigenous microbial communities or commercially available functional strains, and can be single strains or communities. In this invention, the concentration of the loaded target functional bacteria is 10. 8 -10 9The concentration of CFU / mL and the liquid-to-solid ratio of the target functional bacteria to the LDHs-modified matrix are 10:1 to 20:1. It should be noted that the strains used in this invention are not newly screened strains; strains with corresponding functions found in nature can be used as specific examples of the target functional bacteria of this invention.

[0029] Ideally, to enhance the activity of the target functional bacteria and their degradation efficiency for pollutants in specific scenarios, the target functional bacteria can undergo targeted acclimatization treatment before loading. Typical scenarios include anaerobic debromination (degradation of brominated flame retardants, etc.), degradation of high-concentration recalcitrant organic matter (such as nitrobenzene and chlorophenol), extreme environmental treatments such as high-salt / low-temperature treatments, and scenarios requiring enhanced synergistic effects between the strain and the LDHs coating. During acclimatization, the target strain (locally screened bacteria or commercially available bacteria) should be inoculated into an LDHs-modified matrix and placed in a simulated culture medium containing the target pollutant (at a concentration close to the actual remediation scenario) for 3-5 generations of subculturing. The focus is on improving the strain's adhesion to the LDHs coating, its tolerance to the target pollutant, and its degradation activity, laying the foundation for the subsequent efficient synergy between the mineral membrane and the biofilm.

[0030] <Example 1> This example describes the preparation of mineral-based remediation materials for the remediation of lake bottom sediment (overlying water with phosphorus concentration <0.4 mg / L).

[0031] A method for preparing mineral-based ecological remediation materials for lake bottom sediments (overlying water phosphorus concentration <0.4 mg / L) includes the following steps: S1, Pretreatment of the matrix material: Quartz sand is selected as the matrix material, and the matrix material is composed of fine sand (0.075 mm) and coarse sand (0.83 mm), wherein the mass ratio of fine sand to coarse sand is 5:1. The two particle sizes of quartz sand are repeatedly washed with pure water, and then placed in an oven at 50°C to dry until dry, and then taken out for use.

[0032] S2. Preparation of CaFe-LDHs modified matrix: S21. Weigh 250 g of the pretreated matrix material into a 1000 mL beaker and add deionized water to submerge the quartz sand.

[0033] S22. Place the beaker in an 80℃ water bath and add 100 mL each of 0.2 mol / L CaCl2 and 0.1 mol / L FeCl3 solutions. Stir with a stirrer (350-400 rpm) and adjust the pH to 12±0.2 using 10% NaOH solution.

[0034] S23. After stirring continuously for about 3 hours, the moisture has almost evaporated. Place the resulting solid-liquid mixture in an 80℃ oven and age for 18 hours.

[0035] S24. Subsequently, the sand was washed with deionized water until the pH was neutral, and then dried in a 60℃ oven to obtain the CaFe-Cl-LDHs modified matrix.

[0036] Examples 2-5 illustrate a method for preparing mineral-based remediation materials for lake sediments (overlying water phosphorus concentration <0.4 mg / L), using the following divalent metal salts:

[0037] The reaction conditions in Examples 2-5 were the same as those in Example 1; in Example 5, the alkali solution was adjusted to a mixed solution of 1 mol / L NaOH and 0.25 mol / L Na2CO3, the aging temperature was 80°C, the drying temperature was 70°C, and all other reaction conditions were the same as those in Example 1.

[0038] <Example 6> This example describes the preparation of mineral-based remediation materials for the remediation of lake bottom sediment (overlying water phosphorus concentration > 0.4 mg / L).

[0039] A method for preparing mineral-based ecological restoration materials for lake sediment includes the following steps: S1, Pretreatment of the matrix material: Quartz sand is selected as the matrix material, and the matrix material is composed of fine sand (0.075 mm) and coarse sand (0.25 mm), wherein the mass ratio of fine sand to coarse sand is 2:1. The two types of quartz sand are repeatedly washed with pure water, and then placed in an oven at 50°C to dry until dry, and then taken out for use.

[0040] S2. Preparation of ZnAl-Cl-LDHs modified matrix: S21. Weigh 250 g of the pretreated matrix material into a 1000 mL beaker and add deionized water to submerge the quartz sand.

[0041] S22. Place the beaker in an 80℃ water bath and add 100 mL each of 0.2 mol / L ZnCl2 and 0.1 mol / L AlCl3 solutions. Stir with a stirrer (350-400 rpm) and adjust the pH to 12±0.2 using 10% NaOH solution.

[0042] S23. After stirring continuously for about 3 hours, the moisture has almost evaporated. Place the resulting solid-liquid mixture in an 80℃ oven and age for 18 hours.

[0043] S24. Subsequently, the sand was washed with deionized water until the pH was neutral, and then dried in a 60℃ oven to obtain the ZnAl-Cl-LDHs modified matrix.

[0044] S3. Target functional bacteria loading: S31. Select *Pseudomonas putida* GM6 as the target functional bacteria (the strain in this embodiment is a strain in the prior art, such as *Pseudomonas putida* preserved as CCTCC NO: M 2011380, which can achieve the technical effect of the target functional bacteria of this invention); S32. Add 18 g of sterilized ZnAl-Cl-LDHs modified matrix to 360 mL of the bacterial suspension in S31 (OD 600 =0.6), so that bacteria are adsorbed and fixed on the surface of ZnAl-Cl-LDHs modified matrix (180 rpm, 30℃), filtered after 24 h, and the material is rinsed with physiological saline to obtain mineral ecological base remediation material (ZnAl-Cl-GM6-LDHs@quartz sand composite material).

[0045] <Example 7> The difference between Example 7 and Example 6 is that the divalent metal salt is Zn(NO3)2, the trivalent metal salt is Al(NO3)3, the alkaline solution is a mixed solution of 1 mol / L NaOH and 0.25 mol / L Na2CO3, the aging temperature is 80℃, and the drying temperature is 70℃. In this example, a mineral ecological base remediation material (ZnAl-NO3-GM6-LDHs@quartz sand composite material) was prepared.

[0046] <Example 8> This example describes the preparation of mineral-based remediation materials for the remediation of hydrophobic pollutant BDE-47 in dredging dumps in lake shore areas.

[0047] A method for preparing a mineral-based ecological remediation material for degrading the hydrophobic pollutant BDE-47 in dredging dumps along lake shorelines includes the following steps: S1, Pretreatment of the matrix material: Quartz sand with a particle size of 2 mm is selected as the matrix material. The quartz sand is repeatedly washed with pure water, then placed in an oven at 50°C and dried until dry, and then taken out for use.

[0048] S2. Preparation of MgAl-Cl-LDHs modified matrix: S21. Weigh 250 g of the pretreated matrix material into a 1000 mL beaker and add deionized water to submerge the quartz sand.

[0049] S22. Place the beaker in an 80℃ water bath and add 100 mL each of 0.3 mol / L MgCl2 and 0.1 mol / L AlCl3 solutions. Stir with a stirrer (350-400 rpm) and adjust the pH to 12±0.2 using 10% NaOH solution.

[0050] S23. After stirring continuously for about 3 hours, the moisture has almost evaporated. Place the resulting solid-liquid mixture in an 80℃ oven and age for 18 hours.

[0051] S24. Subsequently, the sand was washed with deionized water until the pH was neutral, and then dried in a 60℃ oven to obtain the MgAl-Cl-LDHs modified matrix.

[0052] S3. Target Functional Bacterial Loading: S31. Select LS-1 (the LS-1 mixed bacteria of this invention is prior art; any prior art capable of degrading PBDEs can be used as a specific embodiment of LS-1 of this invention, such as the multifunctional microbial agent disclosed in the invention patent with patent number CN202210104064.0, which can be used as a specific embodiment of LS-1 of this invention) as the target functional bacteria, and acclimate the target functional bacteria. The specific operation of acclimatization is as follows: inoculate LS-1 into a culture medium containing MgAl-Cl-LDHs modified matrix, add hydrophobic pollutant BDE-47 (1 mg / L), and culture under anaerobic conditions for 3-5 generations to obtain the acclimatized target functional bacteria; S32. Add 2 g of sterilized MgAl-Cl-LDHs modified matrix to 20 mL of the bacterial suspension acclimatized in S31 (OD600=0.6), so that the bacteria are adsorbed and fixed on the surface of the MgAl-Cl-LDHs modified matrix (180 rpm, 30℃), 24 After filtration, the material is rinsed with physiological saline to obtain the mineral ecological-based remediation material (MgAl-Cl-LS1-LDHs@quartz sand composite material). <Comparative Example 1> A method for preparing a mineral ecological-based remediation material includes the following steps: S1, Pretreatment of the matrix material: Quartz sand is selected as the matrix material, and the matrix material is composed of fine sand (0.075 mm) and coarse sand (0.83 mm), wherein the mass ratio of fine sand to coarse sand is 5:1. The two particle sizes of quartz sand are repeatedly washed with pure water, and then placed in an oven at 50℃ to dry, and taken out for use.

[0053] S2. Target functional bacterial loading: Pseudomonas sp. GM6 was selected as the target strain. 18 g of sterile substrate material was added to 360 mL of Pseudomonas sp. GM6 bacterial suspension (OD). 600 =0.6), so that bacteria are adsorbed and fixed on the surface of the matrix material (180 rpm, 30℃), filtered after 24 h, and the material is rinsed with physiological saline to obtain the mineral ecological base remediation material (CG1@quartz sand composite material).

[0054] <Comparative Example 2> Silt with a particle size of 0.075 mm was selected as the mineral ecological base remediation material.

[0055] <Comparative Example 3> Coarse sand with a particle size of 0.83 mm was selected as the mineral ecological base restoration material.

[0056] The sampling site for the following experimental examples was Moshui Lake in Wuhan (114°E).o 13'19", 30°N o 32'37").

[0057] <Comparative Example 4> A method for preparing a mineral-based ecological remediation material includes the following steps: S1, Pretreatment of the matrix material: Quartz sand with a particle size of 2 mm is selected as the matrix material. The quartz sand is repeatedly washed with pure water, then placed in an oven at 50°C and dried until dry, and then taken out for use.

[0058] S2, Target Functional Bacterial Loading: LS-1 was selected as the target strain. 2 g of sterile substrate material was added to 20 mL of LS-1 bacterial suspension (OD). 600 =0.6), so that bacteria are adsorbed and fixed on the surface of the matrix material (180 rpm, 30℃), filtered after 24 h, and the material is rinsed with physiological saline to obtain the mineral ecological base remediation material (LS-1@quartz sand composite material).

[0059] Phosphorus adsorption performance test of LDHs modified matrix materials: Fresh lake water was collected at the sampling site, and its initial phosphorus concentration was adjusted to 0.4 mg / L. This water was then added to the systems of Examples 1-5, Comparative Examples 1 and 2 (5 g of remediation material, 50 mL of phosphorus-added lake water). The phosphorus removal rate of the seven remediation materials was tested. The results showed that the ZnFe-Cl-LDHs modified matrix and the MgFe-Cl-LDHs modified matrix had the best removal effect, with removal rates exceeding 90% within 7 h. Under the same experimental conditions, the phosphorus removal rate of Comparative Example 2 was 23.2%, and that of Comparative Example 3 was only 7.7%.

[0060] In-situ capping simulation experiment of micro-lake sediment: Fresh lake sediment was collected from the sampling site, and a simulated column experimental system was constructed in a 250cc syringe. After removing the syringe stopper, a layer of gauze was placed at the bottom, and a filter paper was placed on the gauze to prevent the filling sediment from leaking down. 70 g of lake sediment was filled on the filter paper. 15 g of the ZnFe-Cl-LDHs modified matrix prepared in Example 2 was covered on top of the sediment, and finally 120 mL of lake water was added. Two control groups were set up at the same time: no remediation material (blank) and remediation material added to Comparative Example 1. Experimental results: After 5 days, 4 mL of the upper water sample was taken from the syringe and diluted to 10 mL in a 25 mL colorimetric tube. The phosphorus concentration in the overlying water was measured. The results are shown in Figure 1. The phosphate concentration in the overlying water treated with the ZnFe-Cl-LDHs modified matrix was about 1 / 45 of that in the control group without remediation material; compared with the remediation material in Comparative Example 1, the phosphate concentration in the overlying water was about 1 / 8. The results showed that the ZnFe-Cl-LDHs modified matrix had a significant inhibitory effect on the release of endogenous phosphorus from lake sediments.

[0061] Performance testing of LDH-modified matrix materials as biocarriers: The modified matrix materials prepared in Examples 3 and 4 were inoculated with the model strain *Escherichia coli* DH5α. After 24 hours of membrane-covered culture, the biofilm formation amount was determined using crystal violet staining (characterized by OD540 value). Comparative Example 3 served as a blank control group. As shown in Figure 2, the relative increase in biofilm formation on the modified matrix material prepared in Example 4 reached 100% (i.e., the biofilm formation amount was approximately twice that of the materials in Comparative Example 3 and Example 3).

[0062] Simulation experiment on phosphorus inhibition of microlake sediment by different mineral ecological remediation materials: A 100 mL centrifuge tube simulated a sediment column system. 15 g of air-dried sediment (fresh lake sediment was collected from the sampling site) that had been dried at low temperature and sieved (200 mesh) was added to each tube. Pure water was carefully added along the wall of the tube, and after the sediment was completely wetted, another 70 mL of pure water was added along the wall. After standing for 24 h, 4 g each of ZnAl-NO3-MG6-LDHs@quartz sand composite material, ZnAl-NO3-LDHs@quartz sand composite material, ZnAl-Cl-MG6-LDHs@quartz sand composite material, ZnAl-Cl-LDHs@quartz sand composite material, and MG6@quartz sand composite material were added to the centrifuge tubes. Experimental results: After 5 days, 4 mL of the supernatant water sample was taken from each centrifuge tube, diluted to 10 mL, and the concentrations of total phosphorus (TP) and soluble active phosphorus (SRP) in the supernatant water were measured. The results are shown in Figures 3-4. Compared with the control group (without capping layer) without remediation materials, the increase in phosphorus concentration in the overlying water was effectively controlled. Furthermore, among the mineral-based remediation materials, the ZnAl-NO3-LDHs@quartz sand and ZnAl-NO3-MG6-LDHs@quartz sand treatment groups showed significantly lower results than the chloride ion intercalation treatment group and the control group. Their overlying water concentrations were the lowest, remaining between 0.10-0.15 mg / L and 0.07-0.08 mg / L respectively over 336 h, demonstrating significant phosphorus control effects.

[0063] SEM and EDS images of the MgFe-Cl-LS1-LDHs@quartz sand composite material prepared in Experiment 8 before and after loading with the target functional bacteria were obtained, and the results are shown in Figure 5. The SEM images show the typical layered stacked structure of LDHs, as well as a porous structure and obvious surface roughness. Elemental mapping confirmed the presence of Mg and Fe in MgFe-Cl-LDH@quartz sand, verifying the successful application of the LDH coating. Microscopic observation revealed that tightly adhered micrococci and bacilli adhered to the surface of MgFe-Cl-LS1-LDH@quartz sand, indicating that an effective biofilm was formed on the LDH coating surface, and the material has good biocompatibility. In addition, EDS analysis showed that compared with the control group without colonized biofilm, the carbon mass ratio (21.1%) and atomic occupancy (28.1%) of the biofilm attached to the surface of MgFe-Cl-LS1-LDH@quartz sand increased, further supporting the successful formation of the surface biofilm.

[0064] The degradation ability of the MgFe-Cl-LS1-LDHs@quartz sand composite material prepared in Example 8 for the hydrophobic pollutant BDE-47 was tested. Artificial wastewater with a BDE-47 concentration of 1 mg / L was prepared, and 2 g of MgFe-Cl-LS1-LDHs@quartz sand composite material and 10 mL of artificial wastewater were added to a 15 mL anaerobic tube. The remediation material of Comparative Example 4 was used as a control. The experimental results showed that the removal effect of BDE-47 pollutant under anaerobic conditions exhibited a significant time dependence: after a short-term culture of 8 days, the average removal rate of the MgFe-Cl-LS1-LDHs@quartz sand composite material (corresponding to MgFe-LDHs in the figure) was 33.2%, which was better than the remediation material of Comparative Example 4 (corresponding to no-LDHs in the figure) (28.0%); after a long-term culture of 30 days, the removal effect of the composite material significantly improved to 60.6%, which was better than the remediation material of Comparative Example 4 (56.9%). Meanwhile, an anaerobic pre-enrichment strategy was adopted, in which the MgFe-Cl-LS1-LDHs@quartz sand composite material was pre-cultured for 30 days under anaerobic conditions without BDE-47 before being used in an anaerobic degradation system containing BDE-47. The results showed that the removal rate of BDE-47 in the composite material reached 54.6% within 8 days, which was about 18% higher than the control group (46.3%), with the biological removal rate increasing by 42.4%.

[0065] The specific raw materials listed in this invention, as well as the upper and lower limits and ranges of values ​​for each raw material and process parameter, can all achieve this invention. Examples are not listed individually here. Where there is no conflict, the above embodiments and features described herein can be combined with each other.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a mineral-based ecological remediation material based on LDHs coating, characterized in that, Includes the following steps: S1. Pretreatment of matrix material: Select matrix material, and wash and dry the matrix material in sequence for later use; S2. Preparation of LDHs modified matrix: After the divalent metal salt and trivalent metal salt are mixed and dissolved evenly, a mixed metal solution is obtained. The mixed metal solution is added to the matrix material pretreated in step S1. The pH of the reaction system is adjusted, and after removing excess water from the reaction system, an aging reaction is carried out. After the reaction is complete, the reaction system is washed and dried sequentially to obtain an LDHs-modified matrix with active or passive biofilm loading capacity; S3, select whether to load target functional bacteria according to the remediation requirements. If target functional bacteria are selected, the concentration of the target functional bacteria is 10. 8 -10 9 With CFU / mL and a liquid-to-solid ratio of 10:1 to 20:1 between the target functional bacteria and the LDHs-modified matrix, a mineral ecological-based remediation material with bio-enhanced functionality is prepared after loading the target functional bacteria. If not loaded, the LDHs-modified matrix can promote in-situ microbial coating and growth based on its own biofilm carrier characteristics and can be directly used as a general-purpose mineral ecological-based remediation material.

2. The method for preparing mineral-based ecological remediation materials based on LDHs coatings according to claim 1, characterized in that, In S1, the matrix material is one or more of quartz sand, basalt, volcanic rock, or ceramsite.

3. The method for preparing mineral-based ecological remediation materials based on LDHs coatings according to claim 2, characterized in that, In S1, the particle size of the matrix material can be one or more, wherein the coarse particle size is 0.5-5 mm and the fine particle size is 0.05-0.5 mm; if the matrix material is a mixture of coarse and fine particle sizes, the mass ratio of coarse particle size to fine particle size is 2:1 to 5:

1.

4. The method for preparing mineral-based ecological remediation materials based on LDHs coatings according to claim 1, characterized in that, In S2, both divalent and trivalent metal salts can be one of nitrates, chlorides, and carbonates.

5. The method for preparing mineral-based ecological remediation materials based on LDHs coatings according to claim 4, characterized in that, In S2, the molar ratio of divalent metal cations to trivalent metal cations in both divalent and trivalent metal salts is 1:1 to 1:3, and the divalent metal cation can be Ca. 2+ Mg 2+ Zn 2+ Co 2+ One of the trivalent metal cations is Al. 3+ Fe 3+ One of them.

6. The method for preparing mineral-based ecological remediation materials based on LDHs coatings according to claim 1, characterized in that, In S2, the mass ratio of mixed metal solution to matrix material is 2.5:1 to 10:1, and the total metal ion concentration in the mixed metal solution is preferably 0.5 to 2.0 mol / L.

7. The method for preparing mineral-based ecological remediation materials based on LDHs coatings according to claim 1, characterized in that, In S2, the specific operation for adjusting the pH of the reaction system is as follows: the pH of the reaction system is adjusted to 10±0.2~12±0.2 using alkaline solution; the temperature conditions for the aging reaction are 65~80℃ and the time conditions are 18 h.

8. The method for preparing mineral-based ecological remediation materials based on LDHs coatings according to claim 7, characterized in that, The alkaline solution is one or both of sodium hydroxide solution and sodium carbonate solution.

9. The mineral-based ecological restoration material obtained by the preparation method according to claims 1-8.

10. The application of the mineral ecological base remediation material as described in claim 9 in the control of endogenous pollution in lake sediments.

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