Electrokinetic remediation method based on mineral-microorganism residue complex and application thereof

Abstract

The application discloses a kind of electrokinetic remediation method and application based on mineral-microorganism residual complex, belong to soil remediation technical field, in electrolytic device, under direct current voltage condition, to mineral-microorganism residual complex system electrokinetic remediation is carried out.The important index of the present application will evaluate the ecological effect of soil-soil organic carbon and microbial residual carbon is introduced into the research process of electrokinetic remediation, reveals the coupling mechanism of PFOA removal and soil carbon component turnover in the process of mineral-microorganism residual complex combined electrokinetic remediation, breaks the limitation of this kind of research attention pollutant removal rate, provides a new idea for soil remediation technology.

Description

Technical Field

[0001] This invention belongs to the field of soil remediation technology, and in particular relates to an electrodynamic remediation method based on mineral-microbial residue complex and its application. Background Technology

[0002] Electro-remediation technology is an emerging soil / sediment remediation technology that effectively removes organic and inorganic pollutants from soil / sediments. It boasts advantages such as high controllability, excellent treatment results, ease of installation and operation, low cost, and minimal disruption to the original natural environment, thus maximizing the protection of the original ecosystem while carrying out environmental remediation. The principle of electro-remediation involves inserting electrodes into the contaminated soil area and applying a weak direct current to create an electric field. Utilizing various electro-mechanical effects generated by the electric field, such as electroosmosis, electromigration, and electrophoresis, soil pollutants are driven to migrate directionally along the direction of the electric field, thereby concentrating the pollutants in the electrode area for centralized treatment or separation. Natural mineral materials have a large specific surface area and exhibit adsorption, ion exchange, and chemiluminescence effects on pollutants. After treatment with natural mineral materials, pollutants can be removed from the surface of the mineral materials through filtration or precipitation, allowing for sustainable use and high reusability. Furthermore, it offers advantages such as relatively simple processes, low investment, good results, and minimal secondary pollution. Currently, remediation technologies for perfluorooctanoic acid (pFOA) contaminated soil include physical, chemical, and biological remediation techniques. However, there is currently no technology that can degrade pFOA while simultaneously promoting soil carbon fixation.

[0003] Therefore, how to provide a method for degrading pFOA while promoting soil carbon fixation is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes an electrokinetic remediation method based on a mineral-microbial residue composite and its application.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An electro-repair method based on mineral-microorganism residue complexes is proposed, which involves electro-repairing the mineral-microorganism residue complex system under DC voltage conditions in an electrolysis device.

[0007] Preferably, the mineral-microbial residue complex system is obtained by mixing the mineral-microbial residue complex with soil at a mass ratio of 3:(0-10).

[0008] Preferably, the voltage of the electric repair is 24-32V and the time is 4-7 days, more preferably the voltage is 32V and the time is 4 days.

[0009] Preferably, the concentration of the electrolyte used in the electrolysis device is 0.1-0.15 mol / L, more preferably 0.1 mol / L, and the electrolyte fills the pores of the mineral-microbial residue complex system.

[0010] Beneficial Effects: The removal efficiency of electroremediation in PFOA-contaminated soil is influenced by various factors, with remediation time, voltage, and electrolyte concentration being key factors affecting removal efficiency. This invention found that the PFOA removal rate gradually increases with the extension of remediation time, and begins to stabilize after the 4th day; therefore, 4 days was selected as the optimal remediation time. However, increasing the voltage leads to increased energy consumption. Furthermore, the relationship between electrolyte concentration and remediation effect is non-linear; higher electrolyte concentrations may restrict the migration of ions in the soil. Therefore, selecting a remediation time of 4 days, a voltage of 32V, and an electrolyte concentration of 0.1M are the optimal remediation parameters, with both removal rate and energy consumption within a reasonable range.

[0011] More preferably, the electrode sheet used in the electrolysis device is a titanium-plated platinum electrode sheet.

[0012] Preferably, the electrolyte is one of KCl solution, Na2SO3 solution and Na2SO4 solution, more preferably Na2SO4 solution.

[0013] Beneficial Effects: The electrokinetic remediation system consists of an anode and a cathode as electrode pairs. Electrode voltage loss affects the electrokinetic remediation efficiency of PFOA-contaminated soil. Materials with high electrochemical potential exhibit higher electrode-electrolyte interface losses. For example, when comparing iron and carbon materials as anodes, the voltage loss of the carbon anode was observed to be +1.18V, while that of the iron electrode was -0.44V. Simultaneously, the electrodes may introduce contaminant ions into the system. PFOA remediation typically requires a highly oxidizing environment. Ordinary metal electrodes (such as Fe and Al) are easily corroded or dissolved, while titanium-plated platinum electrodes possess excellent corrosion resistance. Compared to graphite and carbon fiber, titanium-plated platinum electrodes exhibit lower electrode-electrolyte interface voltage loss and higher current efficiency. Furthermore, platinum is a typical active electrode, capable of catalyzing the generation of highly oxidizing free radicals at the anode. These strong oxidants effectively break the C-C and CF bonds in the PFOA molecule. The choice of electrolyte directly affects electroosmotic flow, electromigration, electrode reactions, and the final remediation efficiency. This invention preferably uses Na2SO4 solution as the electrolyte to provide a strong oxidizing system with a "second channel" and to provide stable ionic strength and conductivity, supporting electromigration and working in conjunction with electroosmosis. Simultaneously, in the sulfate medium, the anode can convert SO42- into an electrolyte. 2- Coupling to S2O8 2- Subsequently, it can be activated to generate sulfate free radicals, which work together with hydroxyl free radicals to break the C / C / CF bonds.

[0014] Preferably, the concentration of PFOA in the mineral-microbial residue complex system is 50 mg·kg⁻¹. -1 .

[0015] Beneficial Effects: Soil is the primary sink for PFOA, which accumulates in the soil through atmospheric deposition, surface water runoff, and groundwater infiltration. PFOA distribution in Chinese soils exhibits certain regional characteristics, being particularly common in densely industrialized areas, coastal cities, and some agricultural regions. Surveys of soils within perfluorinated chemical plants revealed PFOA levels ranging from 0.47 to 185 mg / kg. -1 Furthermore, a positive correlation was found between soil SOC content and perfluorinated compounds. The highest PFOA content in fluorination plants in Hengtai and Fuxin reached 623 mg / kg. -1 At 50 mg / kg -1 At representative concentrations, it can enhance the adsorption and fixation of PFOA, promote subsequent biodegradation and mineralization processes, reduce pollutants, and at the same time, the system exhibits good remediation efficiency and system stability.

[0016] Preferably, the mineral-microbial residue complex includes one or more of the following: hematite-microbial residue complex, biotite-microbial residue complex, montmorillonite-microbial residue complex, and kaolinite-microbial residue complex.

[0017] Preferably, the method for preparing the mineral-microbial residue complex includes the following steps:

[0018] Soil suspension is incubated at a constant temperature to obtain inoculum. Minerals and the inoculum are then incubated in a liquid culture medium. After incubation, the mixture is sterilized, centrifuged, washed, and dried to obtain the mineral-microbial residue complex.

[0019] Preferably, when the desired microorganism is a fungus, the liquid culture medium comprises 1 g / L KH₂PO₄, 0.5 g / L MgSO₄, 5 g / L peptone, and 20 g / L glucose, and the incubation time in the liquid culture medium is 24 h; and / or,

[0020] When the required microorganism is bacteria, the liquid culture medium includes 3 g / L beef extract, 10 g / L peptone, 5 g / L NaCl and 6 g / L glucose, and the culture time in the liquid culture medium is 20 h.

[0021] More preferably, the preparation method of the mineral-fungal residue complex includes the following steps:

[0022] (1) Preparation of fungal liquid culture medium: Add 1g KH2PO4, 0.5g MgSO4, 5g peptone and 20g glucose to 1L deionized water, stirring constantly to ensure all components are completely dissolved. Adjust the pH to between 7.0 and 7.2 using 1M HCl and 1M NaOH solutions, then sterilize at 120℃ for 20min. After naturally cooling to room temperature, store in a 4℃ refrigerator for later use.

[0023] (2) Inoculation and Cultivation: Soil and water were mixed at a ratio of 1:15 to prepare a soil suspension. The prepared soil suspension was then incubated in an air bath constant temperature shaker for 12 hours to obtain the inoculum. 3g of sterilized minerals were added to an Erlenmeyer flask. 250mL of the fungal liquid culture obtained in step (1) was added to the Erlenmeyer flask, and 10mL of the soil inoculum was added. The flask was then placed in a shaker for cultivation for 24 hours (logarithmic growth phase of fungi). After the shaker cultivation was completed, the mixture was sterilized by high-pressure steam, and then cultured at 8000r·min. -1 Centrifuge for 10 min. After centrifugation, discard the supernatant, wash the precipitate repeatedly with deionized water and centrifuge again, and finally freeze-dry to obtain the mineral-fungal residue complex.

[0024] More preferably, the method for preparing the mineral-bacterial residue complex includes the following steps:

[0025] (1) Preparation of bacterial liquid culture medium: Add 3g beef extract, 10g peptone, 5g NaCl and 6g glucose to 1L deionized water, stirring constantly to ensure all components are completely dissolved. Adjust the pH to between 7.0 and 7.2 using 1M HCl and 1M NaOH solutions, then sterilize at 120℃ for 20min. After cooling naturally to room temperature, store in a 4℃ refrigerator for later use.

[0026] (2) Inoculation and Cultivation: Soil and water were mixed at a ratio of 1:15 to prepare a soil suspension. The prepared soil suspension was then incubated in an air bath constant temperature shaker for 12 hours to obtain the inoculum. 3g of sterilized minerals were added to an Erlenmeyer flask. 250mL of the fungal liquid culture obtained in step (1) was added to the Erlenmeyer flask, and 10mL of the soil inoculum was added. The flask was then placed in a shaker for cultivation for 20 hours (logarithmic growth phase of fungi). After the shaker cultivation was completed, the mixture was sterilized by autoclaving, and then cultured at 8000r·min. -1 Centrifuge for 10 min. After centrifugation, discard the supernatant, wash the precipitate repeatedly with deionized water and centrifuge again, and finally freeze-dry to obtain the mineral-bacterial residue complex.

[0027] Beneficial effects: Different minerals exhibit significantly different protective effects on microbial residues, and the adaptability of microbial species to the mineral surface environment also varies. Factors influencing changes in organic carbon in microbial residues may involve the mineral's adsorption capacity, redox properties, and the compositional characteristics of the microbial residues themselves. Biotite and kaolinite have relatively weak adsorption capacities; bacterial residues, with their high charge and large specific surface area, are more easily desorbed or oxidized. Fungal residues, on the other hand, are more firmly bound to these mineral surfaces due to the presence of polysaccharides and proteins in their cell walls, resulting in relatively slow degradation.

[0028] Application of an electroremediation method in the removal of PFOA and / or carbon fixation in soil.

[0029] Compared with the prior art, the present invention has the following advantages and technical effects:

[0030] This invention introduces soil organic carbon and microbial residue carbon, important indicators for assessing soil ecological effects, into the research process of electrodynamic remediation. It reveals the coupling mechanism between PFOA removal and soil carbon turnover during the electrodynamic remediation process combined with mineral-microbial residue complexes. This breakthrough overcomes the limitation of this type of research that focuses on pollutant removal rates and provides a new approach for soil remediation technology. Attached Figure Description

[0031] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0032] Figure 1 Structural diagram of the electric repair device used in this embodiment of the invention;

[0033] Figure 2 The removal rates of PFOA in the soil at different remediation times in Example 1 are shown in (a) and (b) respectively.

[0034] In this context, different uppercase letters indicate significant differences between different locations at the same time (P<0.05); different lowercase letters indicate significant differences between different repair times at the same location (P<0.05).

[0035] Figure 3 This refers to the changes in pH value at various locations at different repair times in Example 1;

[0036] Figure 4 The changes in current and electrical energy at different repair times in Example 1;

[0037] Figure 5 The removal rates of PFOA in soil under different remediation voltages in Example 1 are shown in (a) and (b) respectively.

[0038] Figure 6 The pH value changes at various locations under different repair voltages in Example 1;

[0039] Figure 7 The changes in current and electrical energy under different repair voltages in Example 1;

[0040] Figure 8 The removal rates of PFOA in soil at different electrolyte concentrations in Example 1 are shown in (a) and (b) respectively.

[0041] Figure 9 This refers to the pH changes at various locations under different electrolyte concentrations in Example 1;

[0042] Figure 10 The changes in current and electrical energy under different electrolyte concentrations are shown in Example 1.

[0043] Figure 11 This refers to the change in SOC over time during the electro-repair process in Example 2.

[0044] Figure 12 The content and composition of amino sugars in the SOC during the electrorepair process in Example 2;

[0045] Figure 13 The changes in BNC and FNC during the SOC in the electro-repair process of Example 2 are shown in (a) and (b) respectively.

[0046] Figure 14 The change in the FNC to BNC ratio during the SOC in the electro-repair process of Example 2;

[0047] Figure 15 The specific surface area of ​​the minerals in Examples 3-10 and the resulting mineral-microbial residue complex;

[0048] Figure 16 The removal rate of PFOA under the mineral-microorganism complex obtained in Examples 3-10;

[0049] Figure 17 The changes in current and electrical energy during the electric repair process in Examples 3-10;

[0050] Among them, (a) is a mineral-fungal residue complex; (b) is a mineral-bacterial residue complex;

[0051] Figure 18 The changes in organic carbon content in the mineral-microbial residue complex system during the electroremediation process in Examples 3-10;

[0052] Among them, (a) is a mineral-fungal residue complex; (b) is a mineral-bacterial residue complex;

[0053] Figure 19 Fourier transform infrared spectra of different mineral-microbe complexes before and after electrokinetic repair in Examples 3-10;

[0054] Among them, (a) is biotite; (b) is montmorillonite; (c) is kaolinite; and (d) is hematite.

[0055] In the attached diagram, D0-D7 all refer to the repair time, i.e., days 0-7 of the repair process. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels;

[0059] The soil samples were all collected from typical uncontaminated topsoil (0–20 cm) in Fuling District, Chongqing (the Baitao Chemical Industrial Park in this area poses a risk of perfluorooctanoic acid (PFOA) leakage). Following the requirements of the "Guidelines for Long-Term and Short-Term Preservation of Soil Samples" (GB / T32722—2016), the collected soil samples were air-dried naturally in a cool place. After air-drying, the soil was sieved through a 2 mm sieve and stored in a cool place to obtain pretreated soil. The basic physicochemical properties of the background soil are shown in Table 1 (ND indicates not detected).

[0060] Table 1. Basic physicochemical properties of the tested soils

[0061]

[0062]

[0063] The preparation of PFOA-contaminated soil includes the following steps:

[0064] The pretreated soil was treated as described above, and PFOA (dissolved in methanol) was added via spraying while stirring to ensure uniform mixing. The soil was then aged in a dark place at room temperature for 30 days, with periodic stirring during the process, to prepare a 50 mg / kg solution. -1 PFOA contaminated soil samples, of which 50 mg·kg-1 The concentration of PFOA contaminated soil in common industrial areas was determined. Finally, the aged contaminated soil was sterilized by high-pressure steam to obtain PFOA contaminated soil.

[0065] The electric repair device used in the embodiments of the present invention is as follows: Figure 1 As shown, it includes a low-voltage DC power supply, a cathode chamber, and an anode chamber connected in series; a soil chamber is located between the cathode chamber and the anode chamber; the soil chamber includes four soil sampling areas (1-4); the soil chamber is separated from the cathode chamber and the anode chamber by a perforated plexiglass partition, and filter paper is placed inside during use to prevent soil from entering the electrolysis chamber; titanium-plated platinum electrode plates are placed in both the cathode chamber and the anode chamber, and are respectively connected to the positive and negative terminals of the low-voltage DC power supply.

[0066] Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3℃.

[0067] The logarithmic growth phase of fungi in this embodiment of the invention was derived from preliminary microbial culture experiments.

[0068] Example 1

[0069] Adjustment Figure 1 The dimensions of the anode and cathode chambers of the electroremediation device shown are both length × width × height = 50mm × 35mm × 40mm, and the dimensions of the soil chamber are length × width × height = 80mm × 35mm × 40mm. 100g of PFOA-contaminated soil is added to the soil chamber, ensuring the soil is compacted during addition. Equal amounts of Na₂SO₄ solution are then added to both electrolysis chambers as the electrolyte, ensuring the electrolyte completely fills the soil pores. After 24 hours of settling, a low-voltage DC voltage is applied for remediation. Timing begins upon voltage application. During the remediation process, the electrode plates are removed and cleaned every 12 hours. After remediation, the soil in the soil chamber is divided into four equal parts from the cathode to the anode. Figure 1 (1-4) PFOA content and pH were measured. During the first 24 hours of remediation, current changes were recorded hourly, and thereafter every 12 hours. Specific experimental parameters are shown in Table 2 below:

[0070] Table 2 Experimental parameter settings

[0071]

[0072]

[0073] The electrolyte concentration of Group 13 is 0.00, which means that deionized water is used as the electrolyte.

[0074] Example 2

[0075] The only difference from Example 1 is that the low-voltage DC voltage in step (3) is 32V. All other process steps and parameters are the same as in Example 1, specifically including the following steps:

[0076] (3) Adjustment Figure 1 The dimensions of the anode and cathode chambers of the electroremediation device shown are both length × width × height = 50mm × 35mm × 40mm, and the dimensions of the soil chamber are length × width × height = 80mm × 35mm × 40mm. 100g of PFOA-contaminated soil is added to the soil chamber, ensuring the soil is compacted during addition. Equal amounts of Na₂SO₄ solution are then added to both electrolysis chambers as the electrolyte, ensuring the electrolyte completely fills the soil pores. After 24 hours of settling, a low-voltage DC voltage is applied for remediation. The voltage is set to 32V and timing begins. The electrode plates are removed and cleaned every 12 hours during the remediation process. After remediation, the soil in the soil chamber is divided into four equal parts from the cathode to the anode. Figure 1 (1-4) Soil carbon composition was measured. For the first 24 hours of remediation, current changes were recorded hourly, and thereafter every 12 hours. Specific experimental parameters are shown in Table 3.

[0077] Table 3 Experimental parameter settings

[0078]

[0079]

[0080] The electrolyte concentration of Group 9 is 0.00, which means that deionized water is used as the electrolyte.

[0081] Example 3

[0082] Includes the following steps:

[0083] (1) Preparation of fungal liquid culture medium: Add 1g KH2PO4, 0.5g MgSO4, 5g peptone and 20g glucose to 1L deionized water, stirring constantly to ensure all components are completely dissolved. Adjust the pH to between 7.0 and 7.2 using 1M HCl and 1M NaOH solutions, then sterilize at 120℃ for 20min. After naturally cooling to room temperature, store in a 4℃ refrigerator for later use.

[0084] (2) Inoculation and Cultivation: Soil and water were mixed at a ratio of 1:15 to prepare a soil suspension. The prepared soil suspension was then incubated in an air bath constant temperature shaker for 12 hours to obtain the inoculum. 3g of sterilized hematite was added to a conical flask. 250mL of the fungal liquid culture obtained in step (1) was added to the conical flask, and 10mL of the soil inoculum was added. The flask was then placed in a shaker for cultivation for 24 hours (logarithmic growth phase of fungi). After the shaker cultivation was completed, the mixture was sterilized by high-pressure steam, and then cultured at 8000r·min. -1 Centrifuge for 10 minutes. After centrifugation, discard the supernatant, wash the precipitate repeatedly with deionized water and centrifuge again, and finally freeze-dry to obtain the mineral-microbial residue complex, namely the hematite-fungal residue complex.

[0085] (3) Adjustment Figure 1 The dimensions of the anode and cathode chambers of the electroremediation device shown are both length × width × height = 70mm × 35mm × 40mm, and the dimensions of the soil chamber are length × width × height = 40mm × 35mm × 40mm. 30g of the mineral-microbial residue complex obtained in step (2) is added to the soil chamber to achieve a PFOA concentration of 50mg·kg⁻¹. -1 The preparation method is the same as for PFOA-contaminated soil. Equal amounts of Na2SO4 solution are added to both electrolysis chambers as the electrolyte, ensuring the electrolyte completely fills the soil pores. After 24 hours of settling, a low-voltage DC voltage is applied for remediation. The voltage is set to 32V and timing begins. During the remediation process, the electrode plates are removed and cleaned every 12 hours. After remediation, the PFOA content and pH are measured. For the first 24 hours of remediation, current changes are recorded hourly; after 24 hours, current is recorded every 12 hours. Specific experimental parameters are shown in Table 4.

[0086] Table 4

[0087]

[0088] The electrolyte concentration of Group 9 is 0.00, which means that deionized water is used as the electrolyte.

[0089] Example 4

[0090] The only difference from Example 3 is that the hematite-fungal residue complex is replaced with a hematite-bacterial residue complex, specifically including the following steps:

[0091] (1) Preparation of bacterial liquid culture medium: Add 3g beef extract, 10g peptone, 5g NaCl and 6g glucose to 1L deionized water, stirring constantly to ensure all components are completely dissolved. Adjust the pH to between 7.0 and 7.2 using 1M HCl and 1M NaOH solutions, then sterilize at 120℃ for 20min. After cooling naturally to room temperature, store in a 4℃ refrigerator for later use.

[0092] (2) Inoculation and culture: Soil and water were mixed at a ratio of 1:15 to prepare a soil suspension. The prepared soil suspension was then placed in an air bath constant temperature shaker and cultured for 12 hours to obtain the inoculum. 3g of sterilized hematite was added to a conical flask. 250mL of the bacterial liquid culture obtained in step (1) was added to the conical flask, and 10mL of the soil inoculum was added. The flask was then placed in a shaker and cultured for 20 hours (logarithmic growth phase of fungi). After the shaker culture was completed, the mixture was sterilized by high-pressure steam, and then cultured at 8000r·min. -1 Centrifuge for 10 minutes. After centrifugation, discard the supernatant, wash the precipitate repeatedly with deionized water and centrifuge again, and finally freeze-dry to obtain the mineral-microbial residue complex, namely the hematite-fungal residue complex.

[0093] Step (3) is the same as in Example 3.

[0094] Example 5

[0095] The only difference from Example 3 is that the mineral hematite in step (2) is replaced with the mineral biotite, resulting in a biotite-fungal residue complex. All other process steps and parameters are the same as in Example 3.

[0096] Example 6

[0097] The only difference from Example 4 is that the mineral hematite in step (2) is replaced with the mineral biotite, resulting in a biotite-bacterial residue complex. All other process steps and parameters are the same as in Example 4.

[0098] Example 7

[0099] The only difference from Example 3 is that the mineral hematite in step (2) is replaced with the mineral montmorillonite, resulting in a montmorillonite-fungal residue complex. The remaining process steps and parameters are the same as in Example 3.

[0100] Example 8

[0101] The only difference from Example 4 is that the mineral hematite in step (2) is replaced with the mineral montmorillonite, resulting in a montmorillonite-bacterial residue complex. All other process steps and parameters are the same as in Example 4.

[0102] Example 9

[0103] The only difference from Example 3 is that the mineral hematite in step (2) is replaced with the mineral kaolinite, resulting in a kaolinite-fungal residue complex. All other process steps and parameters are the same as in Example 3.

[0104] Example 10

[0105] The only difference from Example 4 is that the mineral hematite in step (2) is replaced with the mineral kaolinite, resulting in a kaolinite-bacterial residue complex. All other process steps and parameters are the same as in Example 4.

[0106] Example 11

[0107] The difference from Example 3 is that in step (3), 30g of the mixture of mineral-microbial residue complex obtained in step (2) and soil (the mass ratio of mineral-microbial residue complex to soil is 3:10) is added to the soil chamber, and the PFOA concentration in the mixture is 50mg·kg. -1 Specifically, it includes the following steps:

[0108] Steps (1) and (2) are the same as in Example 3.

[0109] (3) Adjustment Figure 1 The dimensions of the anode and cathode chambers of the electroremediation device shown are both length × width × height = 70mm × 35mm × 40mm, and the dimensions of the soil chamber are length × width × height = 40mm × 35mm × 40mm. The mineral-microbial residue complex obtained in step (2) is mixed with soil at a mass ratio of 3:10 to obtain a mixture of mineral-microbial residue complex and soil. Referring to the preparation method of PFOA contaminated soil mentioned above, the PFOA concentration in the mixture is made to be 50mg·kg. -1 A complex system of PFOA pollution was obtained. 30g of this PFOA-contaminated complex system was added to the soil chamber, and equal amounts of Na2SO4 solution were added to both electrolysis chambers as the electrolyte, ensuring that the electrolyte completely filled the soil pores. After 24 hours of settling, a low-voltage DC voltage was applied for remediation. The voltage was set to 32V and timing was started. The electrode plates were removed and cleaned every 12 hours during the remediation process. After remediation, the PFOA content and pH were measured. For the first 24 hours of remediation, the current change was recorded hourly; thereafter, the current was recorded every 12 hours. Specific experimental parameters were set as described above.

[0110] Example 3

[0111] Technical effects:

[0112] I. Detection Methods

[0113] 1. Determination of PFOA content in soil

[0114] 1.1 Experimental Procedure:

[0115] Take 2g of soil sample into a 15mL centrifuge tube and add 10mL of methanol solution (V 甲醇 V 水 =1:1) After shaking well, place in a constant temperature shaking incubator and shake at 25℃ and 250 rpm for 60 min. After shaking, extract at 40℃ for 10 min using an ultrasonic cleaner, and then centrifuge at 2500 rpm. -1 Centrifuge at [speed] for 10 min. Repeat the above steps three times. Finally, collect the supernatant, filter it through a 0.22 μm filter membrane into a vial, and perform LC-MS / MS analysis. Specific parameter settings are as follows:

[0116] Chromatographic conditions: Waters 3C18-EB column, column temperature 35℃, flow rate 0.3 mL / min -1 The injection volume was 5 μL, and the mobile phase A was a pure methanol solution and the mobile phase B was a 10 mM ammonium acetate solution.

[0117] Mass spectrometry conditions: ionization mode ESI-, detection mode plasma scanning, orifice flow rate 20 L·hr -1 Electrospray voltage 3kV, solvent removal temperature 300℃, solvent removal flow rate 600L·hr -1 The voltage of the second-stage cone aperture is 3V, the voltage of the sixth-stage rod lens is 0V, the source temperature is 150℃, and the scanning time of each channel is 15min.

[0118] 1.2 The formula for calculating the PFOA removal rate in soil is as follows:

[0119]

[0120] In the formula, C0 represents the concentration of PFOA before the reaction (mg·kg). -1 C1 represents the concentration of PFOA after the reaction (mg·kg⁻¹). -1 ).

[0121] 2. Determination of soil organic carbon (SOC) composition

[0122] Soil organic carbon determination: The determination was carried out in accordance with the standard "Soil Testing Part 6: Determination of Soil Organic Matter" (NY / T 1121.6-2006).

[0123] 3. Determination of soil microbial residual carbon (MNC), including the following steps:

[0124] (1) Weigh 0.5 g of the sample into a hydrolysis tube, add 5 mL of 6M hydrochloric acid, and place in an oven at 105 °C for 8 h for hydrolysis. After the hydrolysate cools to room temperature, add 250 μL of inositol (1 mg·mL⁻¹). -1 Use 1 mL of hydrolysate as an internal standard. Dry the hydrolysate under nitrogen, then dissolve the residue in 20 mL of pure water and adjust the pH to 6.6-6.8. Evaporate to dryness at 80℃ to complete deacidification. Add 5 mL of anhydrous methanol to the deacidified sample to dissolve the residue in the dissolving bottle for desalting. Centrifuge and collect the supernatant, then dry it under nitrogen. Dissolve in 1 mL of deionized water, then add 100 μL of pentanediol (1 mg·mL⁻¹). -1 The sample was used as a recovery material and then lyophilized. Simultaneously, three standard samples were prepared: 100 μL of glucosamine solution, 100 μL of galactosamine solution, 100 μL of mannose solution, 50 μL of muramic acid solution, 100 μL of inositol solution, and 100 μL of pentanediol solution were added to each of the three derivatization bottles. The concentration of each solution was 1 mg / mL. -1 Then add 1 mL of deionized water to obtain a standard sample, and freeze-dry the standard sample and the desalted sample together to obtain the desalted sample.

[0125] (2) First, weigh 320 mg of hydroxylamine hydrochloride and 400 mg of 4-dimethylaminodimehril, dissolve and dilute to 10 mL with a pyridine:methanol = 4:1 (v:v) solution to prepare the derivatization reagent. Next, add 300 μL of the derivatization reagent to the desalting sample and standard sample derivatization flasks, seal tightly, and vortex for 30 s to mix. Incubate in an 80°C water bath for 25 min, shaking every 5 min. After cooling to room temperature, add 1 mL of acetic anhydride, vortex for 30 s to mix, and incubate in an 80°C water bath for 25 min, shaking every 5 min. After cooling to room temperature, add 1.5 mL of dichloromethane, vortex for 30 s to mix. Add 1 mL of 1 mol / L HCl to the derivatization flask, seal, vortex for 30 s, allow to stand for layering, and aspirate the upper inorganic phase. Add 1 mL of pure water and repeat the above steps 3 times. Finally, remove as much of the inorganic phase as possible. Purge the remaining organic phase with nitrogen at 45°C until dry, then dissolve it in 400 μL of diluent (ethyl acetate: n-hexane = 1:1 (v:v)) and transfer it to a gas chromatograph with an inner tube for analysis.

[0126] Carbon calculation of microbial residues

[0127] Based on the principle of the internal standard method, the content of common amino sugars in soil can be calculated using an internal standard substance (inositol). The calculation formula is as follows:

[0128]

[0129] In the formula C i The concentration of the internal standard (mg·kg)-1 ), A i With A x R represents the peak area of ​​inositol and each amino sugar in the sample determination, respectively. f The relative correction factor for each amino sugar is calculated from the correction factors for amino sugars and inositol in the standard sample.

[0130] The content of amino sugars is multiplied by the proportion of carbon atoms in the molecular weight to calculate the content of carbon atoms in a single amino sugar (mg·kg). -1 The calculation formula is as follows:

[0131] Glucosamine carbon (GluN-C) = GluN content × (12 × 6) × 179 - 1 (3)

[0132] In the formula, 12 and 179 represent the atomic weight of C in GluN and the molecular weight of GluN, respectively, and 6 represents the number of C atoms in GluN. The calculation method for the C content of GalN and MurA is similar.

[0133] In the calculation of amino sugars, it is assumed that the molar ratio of MurA to GluN in bacterial cells is 1:2. Fungal GluN is estimated by subtracting bacterial GluN from the total GluN. The calculation formula is as follows:

[0134] Quantification of fungal residue carbon (FNC) (mg·kg) -1 )=(GluN×179.2-1-2×MurA×251-1)×179.2×9(4) Bacterial Residual Carbon (BNC) (mg·kg -1 = MurA × 45(5)

[0135] In the formula, 179.2 and 251 are the molecular weights of GluN and MurA, respectively, 9 is the conversion coefficient of fungal GluN to fungal carbon, and 45 is the conversion coefficient of bacterial MurA to bacterial carbon.

[0136] Microbial residue carbon (mg·kg) -1 ) is the sum of carbon from fungal and bacterial remains.

[0137] 4. Determination of the physicochemical properties of experimental samples

[0138] Soil pH: The pH was determined using the potentiometric method for determining soil pH (HJ 962-2018).

[0139] X-ray diffraction: The sample was passed through a 200-mesh sieve and mineral composition analysis was performed using an X-ray diffractometer. During the analysis, the sample was scanned at room temperature, with scanning angles ranging from 5 (2θ) to 90 (2θ) and a step size of 0.02 (2θ).

[0140] Fourier Transform Infrared Detection: The sample was characterized using a Fourier Transform Infrared Spectrometer. The sample was mixed with KBr at a ratio of 1:100, prepared into a pellet, and then incubated at 400 cm⁻¹. -1 -4000cm -1 Scan within the wavenumber range.

[0141] Specific surface area determination: BET was determined using a fully automated specific surface area and porosity analyzer.

[0142] 5. Energy consumption calculation

[0143] The formula for calculating electrical energy is as follows:

[0144]

[0145] In the formula, E represents the electrical energy (Wh·m³) during the electro-repair process. -3 I is current (A), U is voltage (V), t is time (h), and V is voltage (V). s Soil volume (m) 3 ).

[0146] II. Conclusion:

[0147] 1. Effects of electroremediation parameters on PFOA removal from soil

[0148] 1.1 Repair Time

[0149] The effect of remediation time on the removal of PFOA from soil was investigated by comparing experimental data obtained from the technical solutions in groups 1-7 of Example 1.

[0150] Figure 2 Part (a) shows the removal rate and trend of PFOA under different remediation times. Figure 2 Part (b) shows the removal rate of PFOA at various locations in the three-chamber remediation device at different remediation times. As can be seen from Part (a), the PFOA removal rate gradually increases with time, from an initial 25.10% ± 1.31% to 61.86% ± 1.10%. This trend indicates that the electrokinetic remediation method can effectively remove PFOA from the soil. PFOA contains highly electronegative fluoride ions and carboxylic acid groups, exhibiting hydrophobicity and strong electronegativity. Under the influence of an applied electric field, PFOA in the soil migrates towards the anode, where it is adsorbed and degraded by the titanium-plated platinum electrode in the anode chamber. From day 1 to day 4, the PFOA removal rate increases significantly, rapidly increasing from 25.10% ± 1.31% to 58.94% ± 0.71%. From day 4 to day 7, the increase in removal rate tends to level off, remaining around 60%. Although the removal rate still changes from day 4 to day 7, the rate of increase is significantly reduced.

[0151] As shown in section (b), the removal rate at location 1 was close to 100% at different remediation times. In contrast, the removal rates at locations 2 and 3 gradually increased over time, with location 2 generally showing a higher removal rate than location 3. The PFOA removal rate at location 4 initially increased at a slower rate than other areas, gradually rising to around 60% with prolonged remediation time. Although location 4 should have exhibited the lowest removal rate, its proximity to the anode chamber meant that PFOA might have migrated more easily from the soil to the adjacent electrolyte compared to the soil area, resulting in a higher removal rate than at location 3. Furthermore, the active substances generated at the anode first entered location 4 and reacted with PFOA, further enhancing the removal rate at that location.

[0152] Changes in pH value at various locations at different remediation times:

[0153] During electrostatic remediation, a large amount of OH- ions are generated at the cathode due to the electrolysis of water. Under the influence of the electric field, these OH- ions move from the cathode chamber into the soil chamber, causing an increase in the pH value of the soil near the cathode chamber. Therefore, due to... Figure 3 It can be seen that the pH values ​​at locations 1 and 2 are significantly higher than the initial values, with location 1 reaching a maximum of 12.06 ± 0.05. The pH values ​​at locations 3 and 4 are both lower than the initial pH values, which is related to the oxidation reaction occurring in the anode chamber. Meanwhile, the acidic soil H... + The higher the concentration, the more positive charge the soil surface carries. When PFOA migrates to location 3, it reacts electrostatically with the positively charged soil, limiting its migration within the soil. Therefore, the removal rate at location 3 is relatively low. Location 1 has the highest pH value among the four locations, indicating stronger soil electronegativity. This results in a greater electrostatic repulsion between the soil and PFOA, which is more conducive to PFOA migration and thus leads to a higher PFOA removal rate in the soil.

[0154] Changes in current and electrical energy at different repair times:

[0155] In electroremediation experiments, changes in current are a key indicator for detecting the intensity of soil electrochemical reactions. Changes in current can reflect the extent of the electrolysis reaction, as well as factors such as soil ion concentration, soil conductivity, and electrode reactivity.

[0156] Figure 4 The diagram illustrates the changing trends of current and electrical energy during the repair process. It can be seen that initially, the current at all locations showed a significant increase, then gradually decreased over time, and finally stabilized in the later stages. Figure 4 The embedded graph shows the change in electrical energy over different repair times. Generally, energy consumption is directly proportional to current and time; the higher the current and the longer the time, the greater the electrical energy generated and the higher the energy consumption. Figure 4As can be seen, the electrical energy consumed gradually increases with the extension of the repair time, from the initial 53.26 kWh·m³. -3 Rising to 103.88 kWh·m -3 The energy consumption on day 4 was 78.46 kWh·m³. -3 The difference in energy consumption compared to day 7 is approximately 25 kWh·m³. -3 .

[0157] 1.2 Voltage Parameters

[0158] The effect of remediation voltage on the removal of PFOA from soil was investigated by comparing experimental data obtained from the technical solutions in groups 8-12 of Example 1.

[0159] Depend on Figure 5 As shown in Part (a), the PFOA removal rate exhibits a significant upward trend with increasing voltage. Without applied voltage, the PFOA removal rate is only 11.46% ± 0.68%. After applying voltage, the removal rate increases significantly, with the removal rate at 8V being more than twice that at 0V, and at 32V it being nearly six times that at 0V, reaching 58.94% ± 7.05%. Figure 5 As shown in section (b), location 1 had the highest removal rate, while location 3 had the lowest, consistent with the removal rate trends observed earlier under different remediation times. Under 0V conditions, the removal rates at all locations were low, further demonstrating that the applied electric field was the primary driving force for PFOA removal from the soil. With increasing voltage, the removal rate at location 1 significantly increased, reaching nearly 100% under 32V conditions, thus achieving the remediation target.

[0160] Changes in pH at various locations under different repair voltages:

[0161] from Figure 6 As can be seen, without applied voltage, the pH value of the soil did not differ significantly at different locations. With increasing voltage, the pH value at location 1 increased significantly, exhibiting strong alkalinity overall; the pH value at location 2 also increased, exhibiting neutral to slightly alkaline conditions; the pH values ​​at locations 3 and 4 decreased significantly, exhibiting strong acidity overall. This is related to the redox reactions of the electrodes.

[0162] Changes in current and electrical energy under different repair voltages

[0163] according to Figure 7 The electrical energy diagram shows that as the voltage increases, the electrical energy also increases, resulting in a relatively higher energy consumption. The range of electrical energy consumption is from 2.9 kWh·m³. -3 Up to 78.460 kWh·m -3The electrical energy generated by different repair voltages varies significantly. Although the electrical energy consumed is highest at 32V, the removal rate under the 32V condition is significantly higher than that under 24V, indicating a better repair effect.

[0164] 1.3 Electrolyte Concentration

[0165] The effect of electrolyte concentration on PFOA removal from soil was investigated by comparing experimental data obtained from the technical solutions in groups 13-17 of Example 1.

[0166] according to Figure 8 As shown in section (a), increasing the electrolyte concentration significantly improves the removal rate of PFOA. Furthermore, with increasing electrolyte concentration, the conductivity of the solution improves, and the flow of current is enhanced, thereby improving the PFOA removal effect. Figure 8 As shown in section (b), the PFOA removal rate at all four locations increased with increasing electrolyte concentration, especially at low concentrations (below 0.1M), where the increase was more significant. However, at relatively higher concentrations, the increase in removal rate at each location leveled off, indicating that further increases in electrolyte concentration gradually reduced the effect on the remediation effect.

[0167] pH changes at different locations under different electrolyte concentrations

[0168] according to Figure 9 It can be seen that the pH value at position 1 increases significantly with increasing electrolyte concentration, especially at a concentration of 0.1 M. Compared to position 1, the pH value at position 2 shows a relatively smaller change, while the pH value at position 3 is slightly more stable than that at position 4.

[0169] Changes in current and electrical energy under different electrolyte concentrations

[0170] according to Figure 10 It can be seen that the current decreases with increasing electrolyte concentration, suggesting that the decrease in current may be related to the progress of the electroremediation process. As contaminants are gradually removed, the intensity of the electrochemical reaction may decrease, leading to a reduction in current. For high-concentration electrolyte solutions (0.1M and 0.15M), the initial current values ​​are relatively high, but the rate of decrease is also relatively fast, possibly related to ion migration in the electrochemical reaction. According to the energy diagram, energy consumption increases significantly with increasing electrolyte concentration. When the electrolyte concentration is 0%, the current is small, resulting in low energy consumption and relatively poor remediation effect. The energy consumption at an electrolyte concentration of 0.15M is almost 3.5 times that at 0.1M, but the removal rate only increases from 58.07±1.08% to 61.53±0.66%, indicating a low improvement in remediation effect.

[0171] 2. The impact of electroremediation on soil carbon composition

[0172] The impact of remediation time on soil carbon composition was investigated by comparing experimental data obtained from the technical solutions in groups 1-7 of Example 2.

[0173] Figure 11 The changes in SOC at various locations during the electro-repair process are shown. The SOC content at location 1 decreases with increasing repair time, from 8.85 ± 0.09 g·kg⁻¹. -1 It decreased to 5.68 ± 0.34 g·kg -1 The SOC content at location 2 showed a trend of first increasing and then decreasing, indicating that organic matter migrated towards the anodic region under the influence of the electric field. When the remediation time was extended from 4 days to 7 days, SOC may have migrated further or been degraded by active substances, leading to a decrease in content. The decreasing trend at locations 3 and 4 was slower than that at locations 1 and 2. In summary, based on the changes in SOC content at different locations and times, it can be seen that the electrokinetic remediation process is a dynamic and nonlinear system, which may be affected by migration, chemical reactions, and environmental factors in different regions and stages.

[0174] 3. The impact of electroremediation on microbial residue carbon

[0175] The impact of remediation time on soil microbial residue carbon was investigated by comparing experimental data obtained from the technical solutions in groups 1-7 of Example 2.

[0176] Figure 12 The changes in amino sugar content and composition during electrokinetic remediation are shown in the figure. As can be seen from the figure, the content of all amino sugars decreases with increasing remediation time, with a greater decrease near the cathode (position 1). This indicates that MNCs are decomposed under the influence of the electric field during electrokinetic remediation. The decrease in amino sugar content is more significant in the early stages of electrokinetic remediation, indicating that the effect of electrokinetic remediation on MNCs is a rapid initiation process. The magnitude of change decreases in the later stages of remediation, indicating that the degradation of MNCs tends to reach equilibrium. The change in ManN is relatively small throughout the process, suggesting that it may be more stable. The change in MurA is relatively large, and the variation varies at different locations, indicating that its response to electrokinetic remediation is more complex.

[0177] Figure 13 As shown in section (a), BNC exhibits a decreasing trend during the repair process, with a greater decrease in the early stages than in the later stages. The largest decrease in BNC is observed near the cathode, with position 1 showing a decrease from 1498.41 ± 97.02 mg·kg⁻¹. -1 It decreased to 336.13±25.81 mg·kg -1 .according to Figure 13As shown in section (b), the variation patterns of FNC and BNC are similar in different locations. FNC gradually decreases with prolonged restoration time. Notably, compared to BNC, the variation in FNC is smaller in the later stages of restoration. This indicates that FNC has stronger resistance to interference and is more stable over long periods, which is related to its composition.

[0178] according to Figure 14 It can be seen that the FNC to BNC ratio at location 1 gradually increases with time, indicating that the fluctuations in FNC caused by the electric field are smaller than those in BNC. This is because, during electrokinetic remediation, BNC is more easily decomposed or migrated, while FNC is more stable due to its inherent properties. The trend of change at locations 2-4 is different from that at location 1, showing an initial decrease followed by an increase. In the early stages of remediation, BNC may respond more quickly to the electric field, making it easier to migrate from location 1 to locations 2-4 and recombine with the soil to stabilize within it. The movement of FNC is relatively slower, leading to a decrease in its ratio. As the remediation time increases, most of the migrated BNC is degraded, resulting in an increase in the FNC to FNC ratio.

[0179] 4. Specific surface area of ​​the complex

[0180] The experimental data obtained from the technical solutions in Examples 3-10 were used for investigation.

[0181] Figure 15 The diagram comparing the specific surface areas of minerals and mineral-microbial residue complexes shows that montmorillonite has the largest specific surface area, reaching 237.72 m². 2 ·g -1 Kaolinite is a 1:1 type layered silicate mineral with a relatively fixed interlayer structure, and its specific surface area mainly comes from the outer surface. The specific surface area of ​​hematite and montmorillonite both showed a decreasing trend after being loaded with microorganisms. This may be because the microorganisms adhered to and covered the pores and surface of the minerals.

[0182] 5. Electroremediation effect under mineral-microbial residue complex matrix

[0183] The experimental data obtained from the technical solutions in Examples 3-10 were used for investigation.

[0184] according to Figure 16It was found that the removal rate of PFOA under the mineral-bacterial residue complex was significantly higher than that under the mineral-fungal residue complex. Among the mineral-bacterial residue complexes, the hematite-bacterial residue complex had the highest removal rate, reaching 98.73% ± 0.92%. Hematite has a strong adsorption capacity, which is conducive to bacterial attachment, reproduction, and stability on its surface. When bacterial residues occupy key sites on hematite, the direct binding between PFOA and hematite is weakened, making it easier for PFOA to desorb from the surface of the complex and migrate to the anode chamber under the action of an electric field, thereby improving the overall removal rate of PFOA. In contrast, the interaction between fungal residues and hematite is relatively weak, leaving more adsorption sites for PFOA, thus inhibiting PFOA migration and resulting in a lower removal rate. Kaolinite has a relatively stable structure, and its changes under an electric field are not significant, so its direct impact on PFOA is weak. Therefore, the difference in removal rates between the kaolinite-bacterial residue complex and the fungal residue complex is also relatively small.

[0185] according to Figure 17 It can be seen that the current and energy consumption of the mineral-fungus residue complex and the mineral-bacterial residue complex changed significantly during the remediation process. Overall, the kaolinite-fungus residue complex exhibited the highest current value for most of the time, reaching a maximum of 164 mA, and its energy consumption was consistently higher than other mineral-fungus residue complexes, reaching 1625.30 kW·h·m. -3 In mineral-bacterial residue complexes, the hematite-bacterial residue complex exhibits a higher current value, indicating a corresponding increase in energy consumption. This suggests that disrupting the adsorption of minerals onto microbial residues and PFOA requires greater energy expenditure. Both the montmorillonite-microbial residue complex and the biotite-microbial residue complex, being complexes of minerals and fungal residues, consume even more energy, indicating that disrupting their interactions requires even higher energy consumption. Notably, the kaolinite-bacterial residue complex has the highest energy consumption (896.20 kW·h·m). -3 ) higher than that of biotite-bacterial residue complex (440.60 kW·h·m -3 However, the removal rate did not increase accordingly. The removal rate of kaolinite-bacterial residue complex was 83% ± 2%, and the removal rate of biotite-bacterial residue complex was 88% ± 2%. This indicates that the relationship between energy consumption and removal rate is not a simple linear one, but is affected by factors such as the structure of the mineral and the characteristics of the microbial residue.

[0186] 6. The impact of electroremediation on organic carbon in microbial residues

[0187] The experimental data obtained from the technical solutions in Examples 3-10 were used for investigation.

[0188] Figure 18This is a comparative graph showing the effect of electrokinetic remediation on organic carbon in microbial residues of different mineral-microbial residue complexes. It can be seen that there are significant differences in the changing trends of organic carbon in microbial residues among different mineral-microbial residue complexes. In the kaolinite, biotite, and microbial residue complexes, the decrease in organic carbon in bacterial residues is the largest, decreasing from 2.84 ± 0.29 mg·kg⁻¹. -1 and 1.31±0.01 mg·kg -1 It decreased to 1.60 ± 0.07 mg·kg -1 and 0.77±0.02 mg·kg -1 The organic carbon in fungal residues is relatively more stable, ranging from 3.52 ± 0.26 mg·kg⁻¹. -1 and 2.43±0.26 mg·kg -1 It decreased to 2.21 ± 0.37 mg·kg -1 and 1.45±0.02 mg·kg -1 However, in the complex of montmorillonite, hematite, and microbial residues, the opposite trend was observed, with a more significant loss of organic carbon in the fungal residues, decreasing from 6.85 ± 0.03 mg·kg⁻¹. -1 and 5.04±0.19 mg·kg -1 It decreased to 4.19 ± 0.04 mg·kg -1 and 1.62±0.01 mg·kg -1 This change indicates that different minerals have significantly different protective effects on microbial residues, and that different microbial species have varying degrees of adaptability to the mineral surface environment. Factors influencing changes in organic carbon in microbial residues may involve the mineral's adsorption capacity, redox properties, and the compositional characteristics of the microbial residues themselves.

[0189] Biotite and kaolinite have relatively weak adsorption capacities. Bacterial residues, with their high charge and large specific surface area, are more easily desorbed or oxidized. Fungal residues, on the other hand, bind more firmly to these mineral surfaces due to the polysaccharides and proteins in their cell walls, resulting in relatively slow degradation. It is noteworthy that in montmorillonite complexes, interlayer cation exchange may promote the release of organic carbon from fungal residues, leading to greater organic carbon loss. Normally, fungal carbon, due to its rich content of polysaccharides, proteins, and humic substances, exhibits stronger hydrogen bonding, electrostatic adsorption, and complexation with mineral surfaces, thus possessing a stronger adsorption capacity than bacterial carbon under static conditions. However… Figure 18 The loss of organic carbon was greater in the hematite-fungal residue. This may be because the functional groups in the fungal residue are more prone to redox reactions under an electric field, and the electric field weakens the electrostatic adsorption between the mineral and the organic carbon in the fungal residue. Furthermore, the extracellular polymers of the bacteria may interact with Fe... 3+ This forms a stable complex, thereby reducing the loss of organic carbon in bacterial remains.

[0190] Fourier transform infrared spectra further confirm this difference. Figure 19 It can be seen that in all complexes, the 1630-1650cm... -1 C=O stretching vibration at 3400cm -1 The OH vibration peaks in the vicinity all showed varying degrees of attenuation, indicating a reduction in the organic content of the microbial residues. In both the biotite-microbial residue complex and the kaolinite-microbial residue complex, the 460 cm⁻¹ peak... -1 (Fe-O vibration) and 1033 cm -1 The relatively small change in the (Si-O stretching vibration) peak indicates that the mineral structure is basically stable, while the loss of organic carbon mainly comes from oxidative degradation. In the montmorillonite complex, the 986 cm⁻¹ peak... -1 The shift in the (Si-O vibration) peak may reflect changes in the interlayer structure, further illustrating the impact of cation exchange on the loss of organic carbon in fungal residues. In the hematite complex, at 563 cm⁻¹... -1 (Fe-O vibration) and 475cm -1 The significant change in the (Fe-OH vibration) peak indicates that Fe 3+ Redox reactions occur, which may directly promote the degradation of organic carbon in fungal remains, while potentially protecting the carbon in bacterial remains.

[0191] Combination Figure 18 and Figure 19 The changes observed suggest that the stability of organic carbon in microbial residues is jointly determined by the physical adsorption and chemical oxidation of minerals. Biotite and kaolinite primarily influence the degradation of organic carbon in microbial residues through adsorption, while montmorillonite and hematite are more likely to affect carbon stability through chemical processes (cation exchange and redox reactions). Furthermore, while fungal residue carbon is generally considered more stable, its degradation rate is actually higher in montmorillonite and hematite complexes. This phenomenon may be attributed to the disruption of fungal cell wall components by the specific mineral chemical environment. Therefore, the stability of microbial residue carbon is influenced not only by the adsorption capacity of mineral surfaces but also by the regulation of the mineral chemical environment. In the study of contaminated soil remediation and organic carbon stability, the specific mechanisms of mineral-microorganism interaction should be comprehensively considered.

[0192] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An application of an electrokinetic remediation method based on mineral-microbial residue complexes in the removal of PFOA and carbon fixation in soil, characterized in that, In an electrolytic device, the mineral-microbial residue complex system is electrically repaired under DC voltage conditions; The mineral-microbial residue complex system is obtained by mixing mineral-microbial residue complex with soil at a mass ratio of 3:10; The electric repair process uses a voltage of 24-32V and takes 4-7 days. The concentration of PFOA in the mineral-microbial residue complex system was 50 mg·kg⁻¹. -1 ; The mineral-microbial residue complex includes one or more of the following: hematite-microbial residue complex, biotite-microbial residue complex, montmorillonite-microbial residue complex, and kaolinite-microbial residue complex. The preparation method of the mineral-microbial residue complex includes the following steps: Soil suspension is incubated at a constant temperature to obtain inoculum. Minerals and the inoculum are then cultured in a liquid culture medium for fungi or bacteria. After the culture is completed, the mixture is sterilized, centrifuged, washed, and dried to obtain the mineral-microbial residue complex.

2. The application of the electrokinetic remediation method based on mineral-microbial residue complex according to claim 1 in the removal of PFOA and carbon fixation in soil, characterized in that, The concentration of the electrolyte used in the electrolysis device is 0.1-0.15 mol / L, and the electrolyte fills the pores of the mineral-microbial residue complex system.

3. The application of the electrokinetic remediation method based on mineral-microbial residue complex according to claim 2 in the removal of PFOA and carbon fixation in soil, characterized in that, The electrolyte is one of KCl solution, Na2SO3 solution and Na2SO4 solution.

4. The application of the electrokinetic remediation method based on mineral-microbial residue complex according to claim 1 in the removal of PFOA and carbon fixation in soil, characterized in that, When the required microorganism is a fungus, the liquid culture medium comprises 1 g / L KH₂PO₄, 0.5 g / L MgSO₄, 5 g / L peptone, and 20 g / L glucose, and the culture time in the liquid culture medium is 24 h; and / or, When the required microorganism is bacteria, the liquid culture medium includes 3 g / L beef extract, 10 g / L peptone, 5 g / L NaCl, and 6 g / L glucose, and the culture time in the liquid culture medium is 20 h.

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