Iron-based thin film probe, in-situ analysis method of soil micro-interface pollutant, screening method of iron-based material for soil remediation, and soil remediation method

Abstract

This application provides an iron-based thin-film probe, an in-situ analysis method for soil micro-interface pollutants, a screening method for iron-based materials for soil remediation, and a soil remediation method, belonging to the field of environmental analysis and testing technology. The iron-based thin-film probe, used to study the role of iron-containing mineral micro-interface pollutants in soil, is prepared from an iron sheet through in-situ surface modification; wherein the modified surface formed by the in-situ surface modification is selected from any one of nano-zero-valent iron, iron oxide, and iron sulfide; the iron-based thin-film probe is used to simulate the adsorption, distribution, and redox reactions of iron-containing mineral micro-interface pollutants in soil.

Description

Technical Field

[0001] This application relates to the field of environmental analysis and testing technology, specifically to an iron-based thin film probe, an in-situ analysis method for soil micro-interface pollutants, a screening method for iron-based materials for soil remediation, and a soil remediation method. Background Technology

[0002] With the rapid development of industry and agriculture, the problem of combined heavy metal and organic pollution in soil has become increasingly prominent. Soils not only accumulate heavy metal pollutants such as mercury, cadmium, lead, and arsenic, but also widely contain organic pollutants such as phenolic compounds, organic pesticides, oils, polycyclic aromatic hydrocarbons, and perfluorinated compounds. These pollutants pose a serious threat to the stable operation of soil ecosystems and human health. Therefore, research on soil remediation technologies and their mechanisms of action is of urgent practical significance and important application value.

[0003] In the field of soil remediation materials, iron-based materials (such as zero-valent iron, iron oxides, and iron sulfide) have become a research hotspot and received widespread attention due to their outstanding advantages such as low cost, good environmental compatibility, and magnetic recyclability. However, current research on iron-based materials mainly focuses on the macroscopic assessment of pollutant removal efficiency. A clear and systematic understanding of key scientific issues such as the binding mode, degradation pathway, and reaction mechanism of pollutants at the micro-interface formed between soil particles and iron-based materials under different soil matrices or remediation conditions is still lacking. The adsorption behavior, active binding sites, and transformation trends of pollutants on the surface of iron-based materials directly determine the efficiency of soil remediation and are closely related to the risk of secondary pollution. Failure to accurately reveal these micro-interface behaviors will lead to a lack of targeted design for iron-based remediation materials and may even trigger the migration, diffusion, and re-release of pollutants, severely hindering the engineering application of remediation technologies.

[0004] Furthermore, current research methods for studying the interaction behavior of pollutants at soil micro-interfaces have significant limitations. Traditional analytical methods can only indirectly infer the reaction process at the micro-interface by detecting changes in pollutant concentrations in soil or leachate, making it difficult to achieve in-situ, direct observation of pollutant interfacial behavior. On the other hand, characterization methods using powdered iron-based materials after the reaction are easily affected by complex components in the soil, such as organic matter and silicates, making it impossible to accurately distinguish the true binding state between pollutants and the active sites of the iron-based materials. Simultaneously, the isolated use of multi-scale characterization techniques in existing studies further limits researchers' comprehensive and in-depth understanding of the mechanisms of action of pollutants at soil micro-interfaces.

[0005] Therefore, developing an analytical method that can reveal the adsorption behavior and binding mechanism of pollutants on the surface of iron-based materials in situ and at multiple scales is of great theoretical guiding significance and practical application value for developing efficient and controllable iron-based remediation materials and achieving precise treatment of pollutants in soil. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides an iron-based thin-film probe, an in-situ analysis method for soil micro-interface pollutants, a screening method for iron-based materials for soil remediation, and a soil remediation method, aiming to at least partially solve the above-mentioned technical problems. The specific technical solution provided by this application is as follows.

[0007] As a first aspect of this application, an iron-based thin film probe is provided for studying the role of pollutants at the micro-interface of iron-containing minerals in soil. The iron-based thin film probe is prepared by in-situ surface modification of an iron sheet. The modified surface formed by in-situ surface modification is selected from any one of nano-zero-valent iron, iron oxide, and iron sulfide. The iron-based thin film probe is used to simulate the adsorption, distribution, and redox reactions of pollutants at the micro-interface of iron-containing minerals in soil.

[0008] As a second aspect of this application, an in-situ analysis method for soil micro-interface pollutants using the aforementioned iron-based thin film probe is provided, comprising: placing the iron-based thin film probe in a target soil system for cultivation; removing the iron-based thin film probe after cultivation; performing surface analysis on the iron-based thin film probe using multiple characterization methods in a coordinated manner; and obtaining the adsorption sites, adsorption forms, and transformation trends of pollutants in the target soil system on the surface of the iron-based thin film probe.

[0009] As a third aspect of this application, a method for screening iron-based materials for soil remediation is provided, comprising the following steps: providing at least two iron-based thin-film probes, wherein the modified surface of each iron-based thin-film probe is independently selected from one of nano-zero-valent iron, iron oxide, and iron sulfide; placing the at least two iron-based thin-film probes in a target soil system under the same conditions for parallel cultivation; after cultivation, using the above-mentioned in-situ analysis method for soil micro-interface pollutants, performing surface analysis on each iron-based thin-film probe and obtaining analytical data; based on the analytical data, screening out the iron-based thin-film probe with the best adsorption capacity and conversion efficiency for the target pollutants, and the iron-based material corresponding to the modified surface of the best iron-based thin-film probe is the screened iron-based material for soil remediation.

[0010] As a fourth aspect of this application, a soil remediation method is provided, comprising the following steps: using an iron-based material for soil remediation determined by the above screening method, mixing the iron-based material for soil remediation with target contaminated soil and then performing soil remediation.

[0011] In this embodiment, iron-based thin-film probes with different modified surfaces are prepared through in-situ modification to simulate the micro-interface of iron-containing minerals in soil. Based on this iron-based thin-film probe, an in-situ analysis method for pollutants at the soil micro-interface (hereinafter referred to as the in-situ analysis method) can directly obtain key information on pollutant adsorption and transformation. Combining parallel culture and in-situ analysis screening methods, suitable iron-based materials for soil remediation can be screened. Finally, the screened iron-based materials are mixed with contaminated soil for remediation, achieving targeted treatment. The entire technical solution forms a closed loop of "simulation-analysis-screening-remediation," solving the problems of traditional technologies' difficulty in in-situ mechanism analysis and lack of targeted screening, significantly improving the accuracy, efficiency, and reliability of soil remediation. Attached Figure Description

[0012] Figure 1 The scanning electron microscope image and energy-dispersive X-ray spectroscopy image of the iron oxide-modified iron-based thin film probe prepared in Example 1 of this application are shown.

[0013] Figure 2 The scanning electron microscope image and energy-dispersive X-ray spectroscopy image of the iron-based thin film probe modified with iron sulfide prepared in Example 1 of this application are shown.

[0014] Figure 3 This is a mass spectrum of perfluorinated compounds on the surface of the iron oxide-modified iron-based thin film probe after the culture period in Example 2 of this application.

[0015] Figure 4 This is a mass spectrum of perfluorinated compounds on the surface of the iron-based thin film probe modified with iron sulfide after the culture was completed in Example 2 of this application;

[0016] Figure 5 This is a mass spectrum image of polycyclic aromatic hydrocarbons on the surface of the iron-based thin film probe modified with iron sulfide after the culture is completed in Example 2 of this application;

[0017] Figure 6 This is an X-ray diffraction pattern of the iron-based thin film probe modified with nano-zero valent iron before and after cultivation in Example 2 of this application;

[0018] Figure 7 This is an X-ray diffraction pattern of the iron-based thin film probe modified with iron oxide before and after cultivation in Example 2 of this application;

[0019] Figure 8 This is an X-ray diffraction pattern of the iron-based thin film probe modified with iron sulfide before and after cultivation in Example 2 of this application;

[0020] Figure 9 This is a Fourier transform infrared signal image of the iron-based thin film probe after cultivation in Example 2 of this application;

[0021] Figure 10This is the X-ray photoelectron spectrum of the iron-based thin film probe after cultivation in Example 2 of this application;

[0022] Figure 11 The X-ray photoelectron spectra of Cl on the surface of an iron-based thin film probe modified with nano-zero valent iron in organochlorine pesticide-contaminated soil at different cultivation times in Example 2 of this application are shown.

[0023] Figure 12 This is the energy-dispersive X-ray spectrum of the iron-based thin film probe modified with iron sulfide in Example 2 of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0025] In realizing the concept of this application, it was discovered that existing technologies struggle to reveal the adsorption behavior, binding sites, and transformation mechanisms of pollutants at the micro-interface between iron-based materials and soil particles in situ and directly. The characterization of powdered iron-based materials is easily affected by the complex composition of soil, and isolated characterization methods cannot form a systematic understanding of micro-interface reactions, resulting in a lack of targeted design for iron-based remediation materials. Therefore, this application provides an iron-based thin-film probe, an in-situ analysis method for pollutants at the soil micro-interface, a screening method for iron-based materials for soil remediation, and a soil remediation method. By directionally modifying iron sheets in situ to prepare a single-phase iron-based thin-film probe, and combining multiple characterization methods to analyze the pollutant interaction information on the surface of the iron-based thin-film probe, the optimal iron-based material is screened in parallel and applied to soil remediation. This achieves precise and in-situ analysis of the mechanism of action of pollutants at the soil micro-interface, effectively eliminating interference from soil components, guiding the development of efficient and controllable iron-based remediation materials, and achieving precise treatment of soil pollutants.

[0026] As a first aspect of this application, an iron-based thin film probe is provided for studying the role of pollutants at the micro-interface of iron-containing minerals in soil. The iron-based thin film probe is prepared by in-situ surface modification of an iron sheet. The modified surface formed by in-situ surface modification is selected from any one of nano-zero-valent iron, iron oxide, and iron sulfide. The iron-based thin film probe is used to simulate the adsorption, distribution, and redox reactions of pollutants at the micro-interface of iron-containing minerals in soil.

[0027] In this application embodiment, an iron-based thin film probe is provided. By in-situ surface modification of an iron sheet, a modified surface is formed of a single phase among nano-zero valent iron, iron oxide, and iron sulfide. This surface can accurately simulate the micro-interface environment of corresponding iron-containing minerals in soil. Its thin film structure and in-situ preparation characteristics ensure that the modified surface is stable and can directly reflect the interaction between pollutants and iron-containing minerals. This enables targeted simulation of pollutant adsorption, distribution, and redox reactions, effectively avoiding the shortcomings of traditional iron-based materials in reproducing real micro-interfaces. This provides a structurally stable and accurately simulated dedicated iron-based thin film probe for the study of the action mechanism of pollutants in soil micro-interfaces, ensuring the authenticity and reliability of the research results.

[0028] In some embodiments, when the modified surface formed by in-situ surface modification is nano-zero valent iron, the corresponding in-situ surface modification method is: placing the iron sheet in an inert atmosphere or a reducing atmosphere for heating treatment to obtain an iron-based thin film probe modified with nano-zero valent iron.

[0029] Furthermore, the inert atmosphere is N2, and the reducing atmosphere is H2. The heat treatment temperature is 500-900℃, for example, 500℃, 600℃, 700℃, 800℃, or 900℃; the heat treatment time is 0.5-5h, for example, 0.5h, 1h, 3h, or 5h. The selected iron sheet specifications are: length and width are independently set to 5-20mm, for example, 5mm, 10mm, 15mm, or 20mm; thickness is set to 0.5-5mm, for example, 0.5mm, 1mm, 3mm, or 5mm.

[0030] In some embodiments, when the modified surface formed by in-situ surface modification is an iron oxide, the corresponding in-situ surface modification method is: to use an inorganic acid to corrode the iron sheet, and after washing and drying, to obtain an iron oxide modified iron-based thin film probe.

[0031] Furthermore, the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid. The concentration of the inorganic acid is 0.1-1.0 mol / L, for example, it can be 0.1 mol / L, 0.5 mol / L, or 1.0 mol / L. The mass of inorganic acid used per unit area of ​​iron sheet is 0.1 g / mm². 2 -10g / mm 2 For example, it can be 0.1 g / mm 2 1g / mm 2 5g / mm 2 or 10g / mm 2The etching temperature is 20-30℃, for example, 20℃, 25℃, or 30℃; the etching time is 0.5-5h, for example, 0.5h, 1h, 3h, or 5h. The drying method is air drying at room temperature (20-30℃) or heating drying at 30-100℃, for example, 30℃, 50℃, 80℃, or 100℃.

[0032] In some embodiments, when the modified surface formed by in-situ surface modification is iron sulfide, the corresponding in-situ surface modification method is as follows: using a deposition method, using a sulfur-containing compound as a sulfur source to perform surface treatment on an iron sheet, and growing iron sulfide in-situ on the surface of the iron sheet to obtain an iron-based thin film probe modified with iron sulfide.

[0033] Furthermore, the sulfur source is selected from at least one of sulfur powder, thiourea, and sodium thiosulfate. The mass of sulfur source used per unit area of ​​iron sheet is 1 g / mm². 2 -10g / mm 2 For example, it can be 1g / mm 2 3g / mm 2 5g / mm 2 or 10g / mm 2 The surface treatment temperature is 300-600°C. o Temperature (C) can be, for example, 300℃, 400℃, 500℃ or 600℃; the surface treatment time is 0.5-5h, for example, 0.5h, 1h, 3h or 5h.

[0034] As a second aspect of this application, an in-situ analysis method for soil micro-interface pollutants using the aforementioned iron-based thin film probe is provided, comprising: placing the iron-based thin film probe in a target soil system for cultivation; removing the iron-based thin film probe after cultivation; performing surface analysis on the iron-based thin film probe using multiple characterization methods in a coordinated manner; and obtaining the adsorption sites, adsorption forms, and transformation trends of pollutants in the target soil system on the surface of the iron-based thin film probe.

[0035] This application provides an in-situ analysis method for soil micro-interface pollutants. Utilizing direct contact cultivation between an iron-based thin-film probe and the target soil system, combined with multi-characterization methods, this method directly obtains the adsorption sites, adsorption forms, and transformation trends of pollutants on the iron-based thin-film probe surface, enabling in-situ observation of the interaction behavior of pollutants at the soil micro-interface. This in-situ analysis method eliminates the need for separation treatment of complex soil matrices, directly reflecting the true interaction state between pollutants and the iron-based material micro-interface, providing direct and reliable analytical evidence for research on the interaction mechanisms of pollutants at the soil micro-interface.

[0036] In some embodiments, the above-mentioned multi-representation method linkage is selected from at least two of the following representation methods:

[0037] Matrix-assisted laser desorption / ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FT-ICR-MS) was used to identify contaminants and transformation products adsorbed on the surface of iron-based thin film probes, and semi-quantitative analysis was performed based on signal intensity.

[0038] X-ray diffraction (XRD) was used to scan the surface of the iron-based thin film probe to obtain the phase transformation information of the iron-based thin film probe surface;

[0039] Fourier transform infrared spectroscopy (FTIR) was used to analyze the functional group properties on the surface of the iron-based thin film probe, and to obtain the changes in the surface properties of the iron-based thin film probe and the changes in characteristic absorption peaks caused by the interaction with pollutants.

[0040] X-ray photoelectron spectroscopy (XPS) was used to analyze the elemental composition and valence state distribution of the iron-based thin film probe surface to obtain information on the binding of pollutants to the iron-based thin film probe surface;

[0041] The surface morphology of the iron-based thin film probe was characterized by scanning electron microscopy (SEM) to obtain the changes in surface morphology and elemental distribution of the iron-based thin film probe.

[0042] Furthermore, in the process of conducting research using in-situ analysis methods for soil micro-interface pollutants, multiple characterization methods can be used in conjunction to perform surface analysis on iron-based thin film probes with different modified surfaces. By systematically comparing the adsorption sites, adsorption forms, and transformation trends of pollutants on the surfaces of various iron-based thin film probes, the selective adsorption differences of different types of pollutants on the surface of iron-based thin film materials can be accurately identified. Simultaneously, an unmodified iron sheet can be used as a control sample. This control sample is placed in the target soil system under the same conditions as the iron-based thin film probe and simultaneously cultured and characterized. This effectively eliminates the interference of complex components such as soil organic matter and minerals, thereby clearly confirming the binding characteristics of pollutants to active sites on iron-based thin film probes with different modified surfaces.

[0043] In some embodiments, during the surface analysis of iron-based thin film probes, the XPS spectral changes of non-carbon (C) and oxygen (O) characteristic elements contained in the contaminants on the surface of the iron-based thin film probes can be analyzed by X-ray photoelectron spectroscopy (XPS).

[0044] The aforementioned non-C and non-O characteristic elements may specifically include halogens, heteroatoms, or heavy metal ions in the molecular structure of pollutants. Changes in their XPS spectra are visually reflected in the shifts in the binding energy of characteristic peaks, changes in peak shape, and fluctuations in peak intensity. These spectral changes are directly related to changes in the chemical valence state of the elements and can accurately reflect whether the pollutants undergo oxidation or reduction reactions on the iron-based thin-film probe surface, as well as the corresponding transformation trends. Based on this, the degree of transformation of pollutants on the iron-based thin-film probe surface can be further quantified, thereby scientifically assessing their degradation potential.

[0045] In some embodiments, the target soil system is contaminated site soil or soil simulating contaminants. The target soil system may meet at least one of the following conditions: soil pH value of 6.0-8.0; soil moisture content of 1%-100%; and soil in an aerobic, anoxic, or anaerobic environment. The contaminants in the target soil system include at least one of perfluorinated compounds, polycyclic aromatic hydrocarbons, organochlorine pesticides, heteroatom-containing antibiotics, and heavy metal ions. The concentration of the contaminants in the target soil system is 2 mg / kg-200 mg / kg, for example, 2 mg / kg, 10 mg / kg, 50 mg / kg, 150 mg / kg, or 200 mg / kg. The incubation temperature is 20-50°C, for example, 20°C, 30°C, 40°C, or 50°C; and the incubation time is 6 h-14 d, for example, 6 h, 1 d, 3 d, 5 d, 10 d, or 14 d.

[0046] For example, this application provides an in-situ analysis method for soil micro-interface pollutants, specifically comprising: first, preparing an iron-based thin-film probe with a modified surface of any one of nano-zero-valent iron, iron oxide, or iron sulfide on an iron sheet; then placing the iron-based thin-film probe in a target soil system to allow the iron-based thin-film probe to adsorb and enrich pollutants; subsequently, characterizing the surface of the iron-based thin-film probe using XRD, FTIR, XPS, SEM, and other methods to study the adsorption sites, adsorption forms, and transformation trends of pollutants; and simultaneously, using MALDI-FT-ICR-MS to identify and semi-quantitatively analyze the types of adsorbed pollutants. This in-situ analysis method provides reliable methodological support for in-situ analysis of the interaction modes and strengths between iron-containing minerals and soil pollutants, and for rapidly evaluating the pollutant remediation capacity of iron-based materials.

[0047] As a third aspect of this application, a method for screening iron-based materials for soil remediation is provided, comprising the following steps: providing at least two iron-based thin-film probes, wherein the modified surface of each iron-based thin-film probe is independently selected from one of nano-zero-valent iron, iron oxide, and iron sulfide; placing the at least two iron-based thin-film probes in a target soil system under the same conditions for parallel cultivation; after cultivation, using the above-mentioned in-situ analysis method for soil micro-interface pollutants, performing surface analysis on each iron-based thin-film probe and obtaining analytical data; based on the analytical data, screening out the iron-based thin-film probe with the best adsorption capacity and conversion efficiency for the target pollutants, and the iron-based material corresponding to the modified surface of the best iron-based thin-film probe is the screened iron-based material for soil remediation.

[0048] This application provides a method for screening iron-based materials for soil remediation. By providing at least two iron-based thin film probes with different modified surfaces and conducting parallel cultivation under the same conditions, combined with in-situ analysis methods to obtain analytical data, a direct comparison of the adsorption capacity and conversion efficiency of different iron-based materials for target pollutants is achieved. Based on the screening logic of real micro-interface interaction data, the applicable iron-based materials for soil remediation are determined, solving the problem of lack of specificity in traditional screening. This provides iron-based materials with strong adaptability and controllable effects for soil remediation, ensuring the high efficiency and reliability of remediation technology.

[0049] In some embodiments, the analytical data described above include the relative values ​​of pollutant signal intensity, the uniformity of pollutant distribution on the iron-based thin film probe surface, and the types and amounts of conversion products.

[0050] Furthermore, the relative value of pollutant signal intensity specifically refers to the comparative value of the signal response intensity of the target pollutant on the surface of the iron-based thin film probe detected by multiple characterization methods. This value directly reflects the adsorption capacity and binding affinity of the target pollutant for iron-based thin film probes with different modified surfaces. The higher the signal intensity, the stronger the pollutant adsorption capacity of the corresponding iron-based material.

[0051] The uniformity of pollutant distribution on the iron-based thin film probe surface specifically refers to the spatial distribution of pollutants on the iron-based thin film probe surface observed through various characterization methods. The more uniform the distribution, the higher the utilization rate of the active sites on the corresponding iron-based material surface, and the more stable the adsorption behavior, which can indirectly verify the reliability of its adsorption performance.

[0052] The types and contents of conversion products specifically refer to the types and contents of products generated after pollutants undergo oxidation-reduction reactions on the surface of iron-based thin film probes. The types of products reflect the conversion pathway of pollutants, and the contents of products (especially the contents of harmless degradation products) directly reflect the conversion efficiency of the corresponding iron-based material for pollutants. If a certain type of iron-based material has a high content of target degradation products and a low content of harmful intermediate products, it indicates that its conversion efficiency is better.

[0053] As a fourth aspect of this application, a soil remediation method is provided, comprising the following steps: using an iron-based material for soil remediation determined by the above screening method, mixing the iron-based material for soil remediation with target contaminated soil and then performing soil remediation.

[0054] This application provides a soil remediation method that utilizes iron-based materials selected in advance, which exhibit the best adsorption capacity and conversion efficiency for target pollutants, to directly mix with the target contaminated soil for remediation. This method selects remediation materials based on a precise understanding of the mechanisms of action of pollutants at the soil micro-interface, effectively avoiding the drawbacks of blind selection in traditional remediation materials. It achieves targeted treatment of soil pollutants, significantly improving the specificity and reliability of soil remediation, and ensuring stable and controllable remediation results.

[0055] In some embodiments, the mass ratio of the iron-based material used for soil remediation to the target contaminated soil is 1:100-500, for example, 1:100, 1:200, 1:300, 1:400, or 1:500. The soil remediation temperature is 20-50°C, for example, 20°C, 30°C, 40°C, or 50°C; the soil remediation time is 1-4 weeks, for example, 1 week, 2 weeks, 3 weeks, or 4 weeks.

[0056] In summary, this application provides an iron-based thin-film probe, an in-situ analysis method for soil micro-interface pollutants, a screening method for iron-based materials for soil remediation, and a soil remediation method. Compared with existing methods, this application has the following advantages:

[0057] 1. MALDI-FT-ICR-MS mass spectrometry was applied to the in-situ detection of organic pollutants on the surface of iron-based thin film probes, constructing an in-situ analytical method for soil micro-interface pollutants that combines qualitative and quantitative functions. This MALDI-FT-ICR-MS mass spectrometry technique can directly detect the mass-charge ratio signals of various organic pollutants such as perfluorinated compounds, polycyclic aromatic hydrocarbons, and pentachlorophenols, with a maximum detection concentration of 5.01%. It can accurately analyze the adsorption behavior of organic pollutants on the surface of iron-based thin film probes. Combined with MALDI-FT-ICR-MS and multiple characterization methods such as XPS and SEM, the molecular signals, chemical state information, and morphological changes of pollutants can be simultaneously acquired in the same micro-region, providing key technical support for in-depth analysis of the interfacial interaction mechanism between pollutants and iron-based materials.

[0058] 2. It can effectively distinguish the adsorption differences of different types of pollutants on the surface of iron-based materials. For example, studies on perfluorinated compounds have found that perfluorosulfonic acid compounds have higher signal intensity on the iron oxide-modified iron-based thin film probe surface, while perfluorocarboxylic acid compounds have more significant adsorption on the iron sulfide-modified iron-based thin film probe surface. This confirms that different iron-based materials have selective adsorption characteristics for perfluorinated compounds, providing a direct reference for selecting suitable iron-based materials for sites contaminated with specific types of perfluorinated compounds. At the same time, by setting up control experiments, the interference of organic matter and minerals in the soil was eliminated, clarifying that perfluorinated compounds tend to bind to the metallic iron sites in iron-based materials, helping to clarify the mechanism of action of iron-based materials in complex soil environments.

[0059] 3. This study reveals the potential redox reactions between organic pollutants and iron-based materials at the soil micro-interface, providing new clues for studying the environmental fate of pollutants such as perfluorinated compounds, organochlorine pesticides, and polycyclic aromatic hydrocarbons under the influence of iron-based materials. Furthermore, the iron-based thin film probe preparation method described in this application is simple and controllable, and the surface properties can be adjusted according to research needs. This method can be used to systematically explore the correlation between iron-based material type, surface properties, and pollutant adsorption behavior, laying a methodological foundation for the subsequent development of highly efficient iron-based remediation materials.

[0060] The present application is further illustrated below through embodiments and related test experiments. In the detailed description below, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may be implemented without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict. All instruments, consumables, and reagents used in the following embodiments are commercially available unless otherwise specified.

[0061] Example 1

[0062] In this embodiment, iron-based thin film probes modified with nano-zero valent iron, iron oxide-modified iron-based thin film probes, and iron sulfide-modified iron-based thin film probes were prepared. The specific preparation process is as follows.

[0063] A sheet of iron, 10mm in length and width and 3mm in thickness, is placed in a N2 atmosphere at 700°C. o Heating at high temperature (C) for 3 hours yielded an iron-based thin film probe modified with nano-zero valent iron.

[0064] Iron sheets (10 mm in length and width, and 3 mm in thickness) were etched using 0.5 mol / L dilute hydrochloric acid at room temperature for 3 hours. After etching, the sheets were washed and dried at room temperature to obtain iron oxide-modified iron-based thin film probes.

[0065] A chemical vapor deposition method was used to surface treat iron sheets (10 mm in length and width, and 3 mm in thickness) with sulfur powder at a surface treatment temperature of 400 °C. o C. Iron sulfide was grown in situ on the surface of the iron sheet for 3 hours to obtain an iron-based thin film probe modified with iron sulfide.

[0066] The morphology, structure and elemental distribution of the different iron-based thin film probes prepared above were analyzed using a Hitachi S-8020 field emission scanning electron microscope (SEM).

[0067] Figure 1The images shown are scanning electron microscope (SEM) images and energy-dispersive X-ray diffraction (EDXRD) spectra of the iron oxide-modified iron-based thin film probe prepared in Example 1 of this application; wherein, a is a SEM image of the iron oxide-modified iron-based thin film probe, b is an EXRD spectrum of O element in the region shown in image a, and c is an EXRD spectrum of Fe element in the region shown in image a.

[0068] Figure 2 The images shown are scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDX-ray) spectra of the iron-based thin film probe modified with iron sulfide prepared in Example 1 of this application; wherein, a is a scanning electron microscope image of the iron-based thin film probe modified with iron sulfide, and b is an EDX-ray spectrum of O, S, and Fe elements in the region shown in image a.

[0069] from Figure 1 and Figure 2 As can be seen, this application successfully prepared two types of iron-based thin film probes with stable structures and well-defined phases through in-situ surface modification processes: iron oxide modified iron-based thin film probes were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). It can be seen that the surface of the iron-based thin film probes forms a clear partition of zero-valent iron substrate-iron oxide modified layer. The O element signal completely corresponds to the iron oxide region, and the Fe element is uniformly distributed in the whole region, confirming that the iron oxide modified layer is generated in situ and the substrate structure is complete. The surface of the iron oxide modified iron-based thin film probes exhibits a typical plate-like iron sulfide crystal morphology. EDS elemental superposition analysis shows that the S element and Fe element highly overlap in the crystal region and the O element signal is extremely weak, which clearly indicates that the modified surface is a pure iron sulfide phase without oxide impurities. Both types of iron-based thin film probes can accurately simulate the micro-interface environment of corresponding iron-containing minerals in soil.

[0070] Example 2

[0071] This embodiment uses the iron-based thin film probes with different modified surfaces prepared in Example 1 as research carriers to simulate the adsorption, distribution, and redox reactions of pollutants at the micro-interface of iron-containing minerals in soil. The specific experimental procedure is as follows:

[0072] The contaminated soil used in the experiment was collected from a fluorinated industrial park, a petroleum industry site, and a pesticide production site, respectively. The target pollutants were perfluorinated compounds, polycyclic aromatic hydrocarbons (PAHs), chlorobenzenes, and chlorophenols. Specifically, perfluorinated compounds included perfluorobutane sulfonic acid, perfluorohexane sulfonic acid, perfluoroundecanoic acid, perfluorodecanoic acid, perfluorotridecanoic acid, perfluorooctane sulfonic acid, perfluorovaleric acid, perfluoroheptanoic acid, perfluorodecane sulfonic acid, perfluorooctanoic acid, perfluorotetradecanoic acid, and perfluorononanoic acid; PAHs included α, fluoranthene, pyrene, benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, indo[1,2,3-c,d]pyrene, and dibenzo[a,h]anthracene; and chlorobenzenes and chlorophenols included hexachlorobenzene, trichlorophenol, and pentachlorophenol.

[0073] Iron-based thin film probes with different modified surfaces were placed in the above-mentioned contaminated soil systems and cultured at 20-30℃ for 7-14 days. After the culture was completed, the iron-based thin film probes were removed for subsequent surface analysis.

[0074] The in-situ multi-characterization method linkage analysis of the iron-based thin film probe after cultivation is performed, specifically including the following steps:

[0075] Step 1: Remove the iron-based thin film probe after cultivation and use a Bruker SolariX ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometer equipped with a 15.0T superconducting magnet, combined with matrix-assisted laser desorption / ionization imaging technology (MALDI-FT-ICR-MS imaging technology) to scan and detect the charge-to-mass ratio signals of perfluorinated compounds and polycyclic aromatic hydrocarbons on the surface of the iron-based thin film probe.

[0076] Figure 3 This is a mass spectrum of perfluorinated compounds on the surface of the iron oxide-modified iron-based thin film probe after the culture period in Example 2 of this application. Figure 4 This is a mass spectrum of perfluorinated compounds on the surface of the iron-based thin film probe modified with iron sulfide after the culture was completed in Example 2 of this application; Figure 5 This is a mass spectrum of polycyclic aromatic hydrocarbons on the surface of the iron-based thin film probe modified with iron sulfide after the culture was completed in Example 2 of this application.

[0077] from Figures 3-5 It can be seen that the iron-based thin film probes prepared in this application can effectively adsorb perfluorinated compounds and polycyclic aromatic hydrocarbons in contaminated soil, and achieve in-situ qualitative detection by MALDI-FT-ICR-MS technology: the characteristic mass-charge ratio signals of perfluorinated compounds such as perfluorodecanoic acid, perfluoroundecanoic acid, and perfluorodecanesulfonic acid can be clearly detected on the surface of the iron oxide-modified iron-based thin film probes. The iron-based thin film probes modified with iron sulfide can not only detect perfluorinated compounds such as perfluoroheptanoic acid and perfluorooctanoic acid, but also simultaneously identify the molecular ion peaks of polycyclic aromatic hydrocarbons such as α, benzo[a]pyrene, and benzo[b]fluoranthene. This confirms that iron-based thin film probes with different modified surfaces can selectively adsorb and in-situ characterize different types of organic pollutants, providing direct molecular-level evidence for elucidating the interaction mechanism between soil micro-interface pollutants and iron-containing minerals.

[0078] Step 2: The iron-based thin film probe after the culture was completed was characterized and analyzed using a Bruker D8 ADVANCE X-ray diffractometer (XRD). The target wavelength of Cu was 1.5406 Å, the tube current was 40 mA, and the tube voltage was 40 kV.

[0079] Figure 6 This is an X-ray diffraction pattern of the iron-based thin film probe modified with nano-zero valent iron before and after cultivation in Example 2 of this application; Figure 7This is an X-ray diffraction pattern of the iron-based thin film probe modified with iron oxide before and after cultivation in Example 2 of this application; Figure 8 This is an X-ray diffraction pattern of the iron-based thin film probe modified with iron sulfide before and after cultivation in Example 2 of this application.

[0080] from Figures 6-8 It can be seen that before cultivation, the iron-based thin film probe modified with nano-zero valent iron ( Figure 6 ) and iron oxide modified iron-based thin film probes ( Figure 7 The main phase on the surface of the ) is zero-valent iron (Fe). 0 JCPDS No. 06-0696, magnetite (Fe3O4, JCPDS No. 19-0629) and hematite (Fe2O3, JCPDS No. 39-1346) or maghemite (γ-Fe2O3, JCPDS No. 39-1346); and Fe on the surface of the iron-based thin film probe modified with nano-zero valent iron. 0 The characteristic diffraction peak intensity is significantly higher than that of iron oxide-modified iron-based thin film probes, indicating a higher zero-valent iron content and a more stable substrate. For iron sulfide-modified iron-based thin film probes ( Figure 8 Its surface is mainly composed of magnetite (Fe3O4), pyrite (FeS2, JCPDS No. 37-0475), pyrrhotite (Fe7S8, JCPDS No. 29-0723), tetragonal lepidocrocite (β-FeOOH, JCPDS No. 46-1315), and maghemite (γ-Fe2O3, JCPDS No. 39-1346), exhibiting a complex phase composition distinct from the former two. With the progression of cultivation time (7 to 14 days), the Fe on the surface of the nano-zero-valent iron-modified iron-based thin film probe and the iron oxide-modified iron-based thin film probe... 0 The characteristic peak intensity gradually weakens, indicating that zero-valent iron undergoes further oxidation and transformation. The Fe7S8 characteristic peak on the surface of the iron-based thin film probe modified with iron sulfide shows significant attenuation, but the diffraction peak intensity of its FeS2 component is relatively stable and does not weaken significantly, indicating that the FeS2 phase is more stable in the soil culture environment and has stronger antioxidant capacity.

[0081] Step 3: The chemical composition and molecular structure of the iron-based thin film probe surface after cultivation were analyzed using a Nicolet 6700 Fourier transform infrared spectrometer (FTIR) at a resolution of 4 cm⁻¹. -1 The wavenumber range is 400-4000 cm⁻¹ -1 Under the condition of a signal-to-noise ratio of 50000:1, 32 scans were performed.

[0082] Figure 9 This is a Fourier transform infrared signal image of the iron-based thin film probe after the culture is completed in Example 2 of this application.

[0083] from Figure 9 As can be seen, the characteristic fingerprint peaks of perfluorinated compounds can be clearly identified on the surface of the iron-based thin film probe after cultivation: the C-C stretching vibration peak (1140-1195 cm⁻¹). -1 ), CF stretching vibration peak (1100-1300cm) -1 ), OH / C=O stretching vibration peak (1725-1680 cm⁻¹) -1 The presence of the aforementioned characteristic peaks directly confirms that a significant adsorption and binding interaction occurred between the iron-based thin film probe and the perfluorinated compound, providing spectroscopic evidence for elucidating the interfacial interaction mechanism between the two.

[0084] Step 4: The iron-based thin film probe after cultivation was characterized and analyzed using a Thermo escalab 250Xi X-ray photoelectron spectroscopy (XPS) instrument. The relevant instrument parameters included: using a monochromatic Al Kα with a power of 150W as the excitation source, a full-spectrum pass energy of 100eV, and a narrow-spectrum pass energy of 20eV.

[0085] Figure 10 The images show the X-ray photoelectron spectra of the iron-based thin film probes after cultivation in Example 2 of this application; where a is the high-resolution F 1s spectrum of the iron-based thin film probe modified with nano-zero valent iron, b is the high-resolution F 1s spectrum of the iron-based thin film probe modified with iron oxide, c is the high-resolution F 1s spectrum of the iron-based thin film probe modified with iron sulfide, d is the high-resolution C 1s spectrum of the iron-based thin film probe modified with nano-zero valent iron, e is the high-resolution C 1s spectrum of the iron-based thin film probe modified with iron oxide, and f is the high-resolution C 1s spectrum of the iron-based thin film probe modified with iron sulfide.

[0086] from Figure 10 It can be seen that on the surfaces of the three iron-based thin film probes after cultivation, significant characteristic peaks appeared in the F 1s high-resolution spectra within the binding energy ranges of 688-690 eV and 682-686 eV, corresponding to the FeF2 / FeF3 metal fluorides generated on the iron-based thin film probe surfaces, directly confirming that the perfluorinated compounds underwent an interfacial reaction with the iron-based materials. Simultaneously, the C 1s characteristic peak signal showed a blue shift, while the binding energy of FeF2 / FeF3 showed a red shift. This change indicates that with prolonged cultivation time, the bonding strength of the Fe-F bonds on the iron-based thin film probe surface gradually increased, leading to a weakening of the CF bonds in the perfluorinated compound molecules. This phenomenon, from a chemical state perspective, confirms that the perfluorinated compounds adsorbed on the iron-based thin film probe surface underwent electron transfer from the CF bonds to the iron-based materials, clearly demonstrating that the iron-based thin film probes have significant defluorination reactivity, providing direct evidence of the electron transfer mechanism for the remediation of perfluorinated compound pollution by iron-based materials.

[0087] Figure 11 This is an X-ray photoelectron spectrum of Cl on the surface of an iron-based thin film probe modified with nano-zero valent iron in soil contaminated with organochlorine pesticides at different cultivation times, as shown in Example 2 of this application.

[0088] from Figure 11 It can be seen that with the extension of cultivation time in soil contaminated with organochlorine pesticides, the signal intensity of Cl on the surface of the iron-based thin film probe continuously increases, confirming that the iron-based thin film probe can effectively adsorb and enrich organochlorine pesticides in the soil; at the same time, in addition to the characteristic peaks of organic Cl corresponding to organochlorine structures, the corresponding inorganic Cl gradually appears and is enhanced. - The characteristic peaks indicate that the organochlorine pesticides adsorbed on the surface of the iron-based thin film probe have undergone dechlorination degradation. The C-Cl bonds in the organochlorine molecules are broken and converted into inorganic chloride ions, providing direct spectroscopic evidence for the remediation of organochlorine pesticide pollution by iron-based materials.

[0089] Step 5: The iron-based thin film probe after the culture was completed was characterized using a Japanese Hitachi S-8020 field emission scanning electron microscope (SEM) and a German Multimode8 high-resolution atomic force microscope (AFM).

[0090] Figure 12 The above are the probe energy-dispersive X-ray spectra of iron-based thin films modified with iron sulfide in Example 2 of this application; wherein, a is the energy-dispersive X-ray spectrum of all elements, b is the energy-dispersive X-ray spectrum of F element, c is the energy-dispersive X-ray spectrum of O element, d is the energy-dispersive X-ray spectrum of Fe element, e is the energy-dispersive X-ray spectrum of Si element, and f is the energy-dispersive X-ray spectrum of S element.

[0091] from Figure 12 It can be seen that the F element is densely distributed on the surface of the iron-based thin film probe modified with iron sulfide, and its spatial distribution shows low overlap and obvious spatial separation characteristics with soil organic matter, clay minerals, and silica (Si) particles. This phenomenon intuitively indicates that in the soil micro-interface environment, perfluorinated compounds tend to specifically bind with iron-based materials rather than co-locate with organic matter or silicate minerals in the soil background, thus confirming that iron-based materials have excellent selective adsorption and interfacial binding capabilities for perfluorinated compounds.

[0092] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An iron-based thin-film probe for studying the role of pollutants at the micro-interface of iron-bearing minerals in soil, characterized in that, The iron-based thin film probe is prepared by in-situ surface modification of an iron sheet; The modified surface formed by the in-situ surface modification is selected from any one of nano-zero valent iron, iron oxide, and iron sulfide; The iron-based thin film probe is used to simulate the adsorption, distribution, and redox reactions of pollutants at the micro-interface of iron-containing minerals in soil.

2. The iron-based thin film probe according to claim 1, characterized in that, The in-situ surface modification method is selected from one of the following methods: Iron sheets were heated in an inert or reducing atmosphere to prepare nano-zero-valent iron-modified iron-based thin film probes. Iron oxide-modified iron-based thin film probes were prepared by etching iron sheets with inorganic acids, followed by washing and drying. A deposition method was used to treat an iron sheet with a sulfur-containing compound as the sulfur source, and iron sulfide was grown in situ on the surface of the iron sheet to obtain an iron-based thin film probe modified with iron sulfide.

3. The iron-based thin film probe according to claim 2, characterized in that, When the iron sheet is heated in an inert atmosphere or a reducing atmosphere, the inert atmosphere is N2 and the reducing atmosphere is H2. The heat treatment temperature is 500-900℃, and the heat treatment time is 0.5-5 hours; or, When using inorganic acids to corrode iron sheets, the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid; The corrosion treatment temperature is 20-30℃, and the corrosion treatment time is 0.5-5 hours; or, When surface treatment is performed using a deposition method with sulfur-containing compounds as the sulfur source, the sulfur source is selected from at least one of sulfur powder, thiourea, and sodium thiosulfate. The surface treatment temperature is 300-600°C. o C, the surface treatment time is 0.5-5 hours.

4. A method for in-situ analysis of soil micro-interface pollutants using an iron-based thin-film probe according to any one of claims 1-3, characterized in that, include: The iron-based thin film probe according to any one of claims 1-3 is placed in the target soil system for cultivation; The iron-based thin film probe after cultivation was removed, and surface analysis of the iron-based thin film probe was performed using multiple characterization methods to obtain the adsorption sites, adsorption forms, and transformation trends of pollutants in the target soil system on the surface of the iron-based thin film probe.

5. The method for in-situ analysis of soil micro-interface pollutants according to claim 4, characterized in that, The multi-representation method linkage is selected from at least two of the following representation methods: Matrix-assisted laser desorption / ionization-Fourier transform ion cyclotron resonance mass spectrometry was used to identify pollutants and conversion products adsorbed on the surface of the iron-based thin film probe, and semi-quantitative analysis was performed based on the signal intensity. X-ray diffraction was used to scan the surface of the iron-based thin film probe to obtain phase transformation information of the iron-based thin film probe surface; Fourier transform infrared spectroscopy was used to analyze the functional group properties on the surface of the iron-based thin film probe to obtain the changes in the surface properties of the iron-based thin film probe and the changes in characteristic absorption peaks caused by the interaction with pollutants. X-ray photoelectron spectroscopy was used to analyze the elemental composition and valence state distribution of the iron-based thin film probe surface to obtain information on the binding of pollutants to the iron-based thin film probe surface. The surface morphology of the iron-based thin film probe was characterized using an electron scanning microscope to obtain the surface morphology and elemental distribution changes of the iron-based thin film probe.

6. The method for in-situ analysis of soil micro-interface pollutants according to claim 4, characterized in that, The target soil system is contaminated site soil or soil simulating pollutants; The pollutants include at least one of the following: perfluorinated compounds, polycyclic aromatic hydrocarbons, organochlorine pesticides, antibiotics containing heteroatoms, and heavy metal ions; The culture temperature is 20-50℃, and the culture time is 6h-14d.

7. A method for screening iron-based materials for soil remediation, characterized in that, Includes the following steps: Provide at least two iron-based thin film probes according to any one of claims 1-3, wherein the modified surface of each iron-based thin film probe is independently selected from one of nano-zero valent iron, iron oxide, and iron sulfide; The at least two iron-based thin-film probes were cultured in parallel in a target soil system under the same conditions. After cultivation, the surface analysis of each of the iron-based thin film probes was performed using the in-situ analysis method for soil micro-interface pollutants according to any one of claims 4-6, and the analysis data were obtained. Based on the analysis data, the iron-based thin film probe with the best adsorption capacity and conversion efficiency for the target pollutants was selected, and the iron-based material corresponding to the modified surface of the best iron-based thin film probe is the selected iron-based material for soil remediation.

8. The method for screening iron-based materials for soil remediation according to claim 7, characterized in that, The analytical data includes the relative values ​​of pollutant signal intensity, the uniformity of pollutant distribution on the iron-based thin film probe surface, and the types and contents of conversion products.

9. A soil remediation method, characterized in that, Includes the following steps: Soil remediation is carried out by mixing the iron-based material for soil remediation determined by the screening method described in claim 7 or 8 with the target contaminated soil.

10. The soil remediation method according to claim 9, characterized in that, The mass ratio of the iron-based material used for soil remediation to the target contaminated soil is 1:100-500; The soil remediation temperature is 20-50℃, and the soil remediation time is 1-4 weeks.

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