Composite material based on fe s (112) / beta-fe ooh and method of preparation and use

Abstract

The application discloses a kind of based on FeS (112) / β-FeOOH composite material and preparation method and application, preparation method includes steps: iron salt is dissolved with organic sulfide in alcohol solvent, hydrothermal reaction is carried out under inert atmosphere protection, after reaction is finished, by centrifugation, washing is obtained with 112 crystal face as leading hexagonal FeS nanosheet precursor;FeS nanosheet precursor is dispersed in alkaline solution, by adjusting the content of alkaline solution, the pH value of final product is adjusted to 9~12, constant temperature stirring centrifugation, obtain FeS (112) / β-FeOOH heterojunction composite material.The application exposes FeS (112) high activity crystal face by alkali etching, realizes and β-FeOOH lattice matching bonding, forms triple synergy: interface Fe-O-Fe covalent bond inhibits oxidation, and the material oxidation rate is reduced by 80%; β-FeOOH is oriented nucleation in (112) face, and Cr (VI) reduction efficiency is increased by 2.3 times;Heterojunction accelerates electron transfer, constructs efficient reduction channel, and heavy metal removal rate reaches 2.3 times of physical mixing material, and simultaneously inhibits FeS self-oxidation, provides efficient path for heavy metal pollution treatment.

Description

Technical Field

[0001] This invention relates to the field of environmental functional materials and pollution remediation technology, and in particular to a composite material based on FeS(112) / β-FeOOH, its preparation method and application. Background Technology

[0002] Industrial wastewater discharge, mining operations, and electronic waste disposal lead to the continuous accumulation of heavy metals such as arsenic (As), cadmium (Cd), lead (Pb), and chromium (Cr) in soil and water bodies. These heavy metals can accumulate through the food chain, causing ecotoxicity and threatening human health (such as causing cancer and nerve damage).

[0003] Existing remediation technologies and their limitations: Limitations of adsorption materials. Traditional materials (such as activated carbon, clay minerals, and biochar) rely on physical adsorption or weak ion exchange, which have the following problems: low adsorption capacity for high-valence heavy metals (such as Cr(VI) and As(V)); poor selectivity, easily affected by coexisting ions; insufficient stability after adsorption, posing a risk of secondary release. Single iron-based materials (such as zero-valent iron, FeS, and FeOOH): FeS is easily deactivated in oxidizing environments (generating Fe...). 3+ (leading to structural collapse); although β-FeOOH has an affinity for anionic heavy metals (Cr(VI), As(V)), it has a low specific surface area and is not conducive to Pb. 2+ / Cd 2+ The capture capacity is weak. Existing FeS / FeOOH composite materials mostly employ physical mixing or random coating, resulting in weak interfacial bonding and low electron transfer efficiency; the FeS oxidation problem remains unresolved, leading to insufficient long-term effectiveness; and the active sites are not sufficiently exposed, making it difficult to synergistically adsorb heavy metals of different valence states. Summary of the Invention

[0004] This invention provides a composite material based on FeS(112) / β-FeOOH, its preparation method, and its application. This invention is the first to propose controlling the heterojunction interface through crystal plane engineering: directional exposure of the highly active (112) crystal plane of FeS (rich in unsaturated coordinated Fe atoms); achieving lattice-matched chemical bonding between FeS(112) and β-FeOOH in an alkaline environment to form a stable heterojunction; synergistically enhancing the resistance to cations (Pb). 2+ Cd 2+ The ability to capture ions (Cr(VI), As(V)) and anions (Cr(VI), As(V)) and the stability of materials are improved to overcome the above problems.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention provides a method for preparing a composite material based on FeS(112) / β-FeOOH, comprising the following steps:

[0007] Synthesis of S1: FeS(112) nanosheet precursor:

[0008] Iron salts and organic sulfides were dissolved in alcohol solvents and subjected to hydrothermal reaction under an inert atmosphere. After the reaction was completed, the mixture was centrifuged and washed to obtain a hexagonal FeS nanosheet precursor dominated by the 112 crystal plane.

[0009] S2: In-situ construction of β-FeOOH heterojunctions:

[0010] The FeS nanosheet precursor was dispersed in an alkaline solution, and the pH of the final product was adjusted to 9-12 by adjusting the content of the alkaline solution. After constant temperature stirring and centrifugation, FeS(112) / β-FeOOH heterojunction composite material was obtained, wherein the mass ratio of FeS to β-FeOOH was 1:1 to 10:1.

[0011] Furthermore, the iron salt and the organic sulfide are in a molar ratio of 1:2 to 1:5; the concentration of the alkaline solution is 0.5 to 2M.

[0012] Furthermore, the iron salt is selected from one or more of ferric nitrate, ferric chloride, ferric sulfate, or ferric carbonate;

[0013] The organic sulfide is selected from one or more of divalent sulfides and high-valent sulfides.

[0014] The divalent sulfides include thiols, thioethers, disulfides, polysulfides, and cyclic sulfides, and the high-valent sulfides include sulfones and sulfonic acids;

[0015] The alcohol solvent is selected from one or more of ethylene glycol, methanol, propanol, and glycerol, and its hydroxyl density regulates the growth kinetics of FeS crystal faces.

[0016] Furthermore, the alkaline solution is selected from one or more aqueous solutions of NaOH, Na2CO3, and Ca(OH)2.

[0017] Furthermore, the conditions for the hydrothermal reaction are: 150–300°C, reaction time 2–6 hours;

[0018] The conditions for constant temperature stirring are: constant temperature stirring at 50-80℃ for 4-8 hours.

[0019] In another aspect, the present invention provides a composite material based on FeS(112) / β-FeOOH prepared according to the preparation method described above.

[0020] In another aspect, the present invention provides the application of the FeS(112) / β-FeOOH based composite material in the remediation of heavy metal polluted water bodies. The FeS(112) / β-FeOOH based composite material is added to the heavy metal polluted water body, stirred and mixed until the pH value is 9-12, and then separated by sedimentation.

[0021] Furthermore, the heavy metal includes Pb. 2 +、Cd 2 +, As(V), Cr(VI) or one or more; the addition ratio of the composite material is 0.1 wt.%-10 wt.%.

[0022] In another aspect, the present invention provides the application of the FeS(112) / β-FeOOH based composite material in the remediation of heavy metal contaminated soil. The FeS(112) / β-FeOOH based composite material is added to heavy metal contaminated soil in a certain proportion, mixed evenly, and the soil pH is tested to ensure that the soil environment pH value is within the range of 9 to 12.

[0023] Furthermore, the heavy metal includes Pb. 2 +、Cd 2 +, As(V), Cr(VI) or one or more of the following;

[0024] The composite material is added at a rate of 0.1 wt.% to 10 wt.%.

[0025] The beneficial effects of this invention are:

[0026] This invention exposes the highly active crystal plane of FeS(112) through alkaline etching and achieves lattice-matched bonding with β-FeOOH, generating a triple synergistic effect:

[0027] Firstly, interfacial bonding inhibits oxidation: FeS(112) unsaturated Fe atoms form Fe-O-Fe covalent bonds with β-FeOOH hydroxyl groups, which reduces the oxidation rate of the material by 80%.

[0028] Secondly, the active site is selectively enriched: β-FeOOH selectively nucleates on the (112) face, which increases the reduction efficiency of Cr(VI) by 2.3 times;

[0029] Third, the heterojunction interface accelerates electron transfer: β-FeOOH acts as an electron acceptor, accepting electrons transferred from the FeS(112) surface through Fe-O-Fe covalent bonds, forming a highly efficient reduction channel. This structure enables the removal rate of heavy metals to reach 2.3 times that of physical mixed materials, while inhibiting the self-oxidation of FeS through electron transfer. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The X-ray diffraction results of the (112) crystal plane-dominated FeS nanosheet precursor prepared in Example 1 of this invention are shown.

[0032] Figure 2 The image shows a TEM image of the FeS(112) / β-FeOOH solution prepared in Example 1 of this invention. Figure 2 (a) is a high-resolution transmission electron microscope (HRTEM) image. Figure 2 (b) is the Fast Fourier Transform (FFT A) graph; 2(c) is the Fast Fourier Transform (FFT B) graph. Figure 2 (d) is a crystal structure model diagram. Figure 2 (e) is a scanning electron microscope (SEM) image. Figure 2 (f) is the elemental mapping diagram of Fe energy spectrum. Figure 2 (g) is the elemental mapping diagram of the S element energy spectrum. Figure 2 (h) is the elemental mapping diagram of the O element energy spectrum;

[0033] Figure 3 This is a comparison of the S2p spectra of FeS(112) / β-FeOOH prepared in Example 1 of this invention and the FeS nanosheet precursor of Comparative Example 1. Figure 3 (a) is the S2p spectrum of the FeS(112) / β-FeOOH heterojunction composite material in Example 1. Figure 3 (b) is the S2p spectrum of the FeS nanosheet precursor of Comparative Example 1. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0035] Example 1:

[0036] A method for preparing a composite material based on FeS(112) / β-FeOOH includes the following steps:

[0037] Synthesis of S1: FeS(112) nanosheet precursor:

[0038] Ferric nitrate and thiourea were dissolved in methanol at a molar ratio of 1:3 and reacted hydrothermally at 150°C for 2 hours under N2 protection. The product was centrifuged and washed with ethanol to obtain a FeS nanosheet precursor dominated by the (112) crystal plane. The X-ray diffraction (XRD) results are as follows. Figure 1 As shown.

[0039] S2: In-situ construction of β-FeOOH heterojunctions:

[0040] 1 g of FeS nanosheet precursor was dispersed in 100 mL of 2 M NaOH solution to achieve a pH of 12. The mixture was stirred and centrifuged at 60 °C for 6 h to obtain a FeS(112) / β-FeOOH heterojunction composite solution, where the mass ratio of FeS to β-FeOOH was 1:1. TEM analysis of the product yielded the following results: Figure 2 As shown, the crystal planes forming FeS(112) are determined, and β-FeOOH is adsorbed. Figure 2 a-2c), using VESTA software ( Figure 2 d) It is clear that this facet has four iron atoms. Compared with the iron atoms of the low-index crystal facet, the iron atoms of the high-index crystal facet tend to be in unsaturated coordination. They have a strong affinity for polar molecules (especially water molecules and hydroxyl groups) and are easy to adsorb and bind these molecules. Since the (112) facet provides abundant and highly active iron atom sites (4 per unit cell) and its structure is conducive to the stability of FeOOH crystal nuclei, the SEM-mapping analysis results of the FeS(112) / β-FeOOH sample are as follows: Figure 2 e-2h shows (especially the parts with yellow and green dashed circles) that the distribution of O element (from β-FeOOH) on the surface of FeS particles exhibits obvious localized enrichment rather than uniform coverage. This is consistent with theoretical expectations that β-FeOOH preferentially nucleates and grows on the exposed (112) crystal plane's highly active sites, forming local heterostructures rather than uniform coating. The S2p spectrum of FeS(112) / β-FeOOH shows enhanced SOx group signal at 168.4 eV ( Figure 3 a) The reason is that in the early stage of coating formation, the (112) facet of FeS is rich in Fe atoms, giving it a high adsorption affinity for polar molecules. The generated sulfates and other oxygen-containing sulfur species have poor solubility and tend to adsorb or deposit on the FeS / FeOOH surface or interface. The S2p spectrum in Example 1 is compared with the S2p spectrum in Comparative Example 1. x The peak area decreased by 80%, indicating that the FeS(112) / β-FeOOH material has an 80% lower oxidation rate than pure FeS.

[0041] Heavy metal contaminated water testing:

[0042] The prepared FeS(112) / β-FeOOH solution was added to the heavy metal wastewater at a rate of 0.1 wt.% of the polluted water body mass. The pH of the system was adjusted to 10 (5%–10% sodium hydroxide solution was used when pH < 9, and 1% citric acid solution was used when pH > 12). The mixture was stirred for 30 min until the precipitate settled naturally. The supernatant was taken for inductively coupled plasma (ICP) testing. The test results are shown in Table 1. The concentrations of heavy metal ions all met the national emission standards.

[0043] Soil remediation test:

[0044] The prepared FeS(112) / β-FeOOH composite material was added to the heavy metal contaminated soil at 0.1 wt.% of the contaminated soil mass. The characteristics of the heavy metal contaminated soil before treatment are shown in Table 2. The composite material was thoroughly mixed with the soil, and 15 points were sampled using the S-type sampling method to comprehensively test the pH to ensure that the soil pH was 9 (5% to 10% sodium hydroxide solution was used when pH < 9, and 1% citric acid solution was used when pH > 12). The soil remediation effect is shown in Table 3. It can be seen that the remediation effect of heavy metal ions reached more than 85%.

[0045] Example 2:

[0046] A method for preparing a composite material based on FeS(112) / β-FeOOH includes the following steps:

[0047] S1: Ferric chloride and thiosulfonate were dissolved in glycerol at a molar ratio of 1:5 and reacted at 200℃ for 5 hours under hydrothermal conditions, with N2 protection introduced; the product was centrifuged and washed with ethanol to obtain FeS nanosheet precursor dominated by (112) crystal plane.

[0048] S2: Take 1g of FeS nanosheet precursor and disperse it in 100mL of 0.5M Na2CO3 solution. Stir at 60℃ for 6h. Centrifuge and wash until pH=11 to obtain FeS(112) / β-FeOOH solution, wherein the mass ratio of FeS to β-FeOOH is 10:1.

[0049] Heavy metal contaminated water testing:

[0050] The prepared FeS(112) / β-FeOOH solution was added to the heavy metal wastewater at 10 wt.% of the polluted water body mass. The pH was adjusted to 9 (the pH adjustment method was the same as in Example 1). The mixture was stirred for 30 min until the precipitate settled naturally. The supernatant was taken for inductively coupled plasma (ICP) testing. The test results are shown in Table 1. The concentrations of heavy metal ions all met the national emission standards.

[0051] Soil remediation test:

[0052] The prepared FeS(112) / β-FeOOH composite material was added to the heavy metal contaminated soil at 10 wt.% of the contaminated soil mass. The characteristics of the heavy metal contaminated soil before treatment are shown in Table 2. The composite material was thoroughly mixed with the soil, and 15 points were sampled using the S-type sampling method to comprehensively test the pH to ensure that the soil pH was 10 (the soil pH adjustment method was the same as in Example 1). The soil remediation effect is shown in Table 3. The composite material in this example achieved a remediation effect of more than 85% on heavy metal ions.

[0053] Example 3:

[0054] A method for preparing a composite material based on FeS(112) / β-FeOOH includes the following steps:

[0055] S1: Iron carbonate and thioacetamide were dissolved in methanol at a molar ratio of 1:3 and reacted at 200℃ for 5 hours to carry out a hydrothermal reaction under N2 protection. The product was centrifuged and washed with ethanol to obtain FeS nanosheet precursor dominated by (112) crystal plane.

[0056] S2: Take 1g of FeS nanosheet precursor and disperse it in 100mL of 1M Ca(OH)2 solution. Stir at 60℃ for 6h. Centrifuge and wash until pH=11 to obtain FeS(112) / β-FeOOH solution, wherein the mass ratio of FeS to β-FeOOH is 5:1.

[0057] Heavy metal contaminated water testing:

[0058] The prepared FeS(112) / β-FeOOH solution was added to the heavy metal wastewater at 5 wt.% of the mass of the polluted water body. The pH was adjusted to 10 (the pH adjustment method was the same as in Example 1). The mixture was stirred for 30 min until the precipitate settled naturally. The supernatant was taken for inductively coupled plasma (ICP) testing. The test results are shown in Table 1. The concentrations of heavy metal ions all met the national emission standards.

[0059] Soil remediation test:

[0060] The prepared FeS(112) / β-FeOOH composite material was added to the heavy metal contaminated soil at 5 wt.% of the contaminated soil mass. The characteristics of the heavy metal contaminated soil before treatment are shown in Table 2. The composite material was thoroughly mixed with the soil, and 15 points were sampled using the S-type sampling method to comprehensively test the pH to ensure that the soil pH was 11 (the soil pH adjustment method was the same as in Example 1). The soil remediation effect is shown in Table 3, and the remediation effect of heavy metal ions reached more than 85%.

[0061] Example 4:

[0062] A method for preparing a composite material based on FeS(112) / β-FeOOH includes the following steps:

[0063] S1: Ferric chloride and methanesulfonate were dissolved in ethylene glycol at a molar ratio of 1:2 and reacted at 200°C for 5 hours under hydrothermal conditions, with N2 protection introduced; the product was centrifuged and washed with ethanol to obtain FeS nanosheet precursor dominated by (112) crystal plane;

[0064] S2: Take 1g of FeS nanosheet precursor and disperse it in 100mL of 2M Ca(OH)2 solution. Stir at 60℃ for 8h, centrifuge and wash until pH=11 to obtain FeS(112) / β-FeOOH solution, wherein the mass ratio of FeS to β-FeOOH is 4:1.

[0065] Heavy metal contaminated water testing:

[0066] The prepared FeS(112) / β-FeOOH solution was added to the heavy metal wastewater at 3 wt.% of the mass of the polluted water body. The pH was adjusted to 10 (the pH adjustment method was the same as in Example 1). The mixture was stirred for 30 min until the precipitate settled naturally. The supernatant was taken for inductively coupled plasma (ICP) testing. The test results are shown in Table 1. The concentrations of heavy metal ions all met the national emission standards.

[0067] Soil remediation test:

[0068] The prepared FeS(112) / β-FeOOH composite material was added to the heavy metal contaminated soil at 3 wt.% of the contaminated soil mass. The characteristics of the heavy metal contaminated soil are shown in Table 2. The composite material was thoroughly mixed with the soil, and 15 points were sampled using the S-type sampling method to comprehensively test the pH to ensure that the soil pH was 9 (the soil pH adjustment method was the same as in Example 1). The soil remediation effect is shown in Table 3, and the remediation effect of heavy metal ions reached more than 85%.

[0069] Comparative Example 1:

[0070] A method for preparing FeS nanosheet precursor, comprising the following steps:

[0071] Ferric nitrate and thiourea were dissolved in methanol at a molar ratio of 1:3 and reacted hydrothermally at 150°C for 2 hours under N2 protection. The product was centrifuged and washed with ethanol to obtain FeS nanosheet precursors dominated by the (112) crystal plane. Samples were taken for XPS testing. Figure 3 b).

[0072] Heavy metal contaminated water testing:

[0073] The prepared FeS nanosheet precursor solution was added to the heavy metal wastewater at a rate of 0.1 wt.% of the polluted water body mass. An alkaline solution was added to adjust the pH to 10 (the pH adjustment method was the same as in Example 1). The mixture was stirred for 30 minutes until the precipitate settled naturally. The supernatant was taken for inductively coupled plasma (ICP) testing. The test results are shown in Table 1. The concentrations of each heavy metal were higher than the national standards.

[0074] Soil remediation test:

[0075] The prepared FeS nanosheet precursor was added to heavy metal-contaminated soil at 0.1 wt.% of the soil mass. The characteristics of the heavy metal-contaminated soil are shown in Table 2. The composite material was thoroughly mixed with the soil, and pH was measured at 15 points using the S-type sampling method to ensure the soil pH was at least 9 (the soil pH adjustment method was the same as in Example 1). The soil remediation effect is shown in Table 3, indicating a poor remediation effect, with the remediation rate of heavy metal ions being less than 10%.

[0076] Comparative Example 2:

[0077] A method for preparing FeS / β-FeOOH, comprising the following steps:

[0078] Ferric chloride and thiosulfonate were dissolved in glycerol at a molar ratio of 1:5 and reacted at 200°C for 5 hours under hydrothermal conditions, with N2 protection. The product was centrifuged and washed with ethanol to obtain FeS nanosheet precursors dominated by (112) crystal planes.

[0079] 1 g of FeS nanosheet precursor was dispersed in 100 ml of 0.5 M Na2CO3 solution, stirred at 60 °C for 6 h, and centrifuged and washed until pH = 11 to FeS(112) / β-FeOOH solution, wherein the mass ratio of FeS to β-FeOOH was 6:1.

[0080] Heavy metal contaminated water testing:

[0081] The prepared FeS(112) / β-FeOOH solution was added to the heavy metal wastewater at a rate of 0.1 wt.% of the polluted water body mass. An acidic solution (HCl) was added to adjust the pH to 3. The mixture was stirred for 30 minutes until the precipitate settled naturally. The supernatant was then subjected to inductively coupled plasma (ICP) testing. The test results are shown in Table 1. The concentrations of each heavy metal were all higher than the national standards.

[0082] Soil remediation test:

[0083] The prepared FeS nanosheet precursor was added to heavy metal-contaminated soil at 0.1 wt.% of the soil mass. The characteristics of the heavy metal-contaminated soil are shown in Table 2. The composite material was thoroughly mixed with the soil, and an acidic solution (HCl) was added. The pH was measured at 15 points using the S-type sampling method to ensure the soil pH was below 4. The soil remediation effect is shown in Table 3, indicating that the remediation effect for heavy metal ions was less than 10%.

[0084] Comparative Example 3:

[0085] A method for preparing a FeS / β-FeOOH physical mixed solution, comprising the following steps:

[0086] Ferric carbonate and thioacetamide were dissolved in methanol at a molar ratio of 1:3 and reacted at 200°C for 5 hours to carry out a hydrothermal reaction under N2 protection. The product was centrifuged and washed with ethanol to obtain FeS nanosheet precursors dominated by the (112) crystal plane.

[0087] Take 1g of FeS nanosheet precursor and 1g of β-FeOOH to form a mixed solution, stir at 60℃ for 6h, centrifuge and wash until pH=11 to obtain FeS / β-FeOOH physical mixed solution, wherein the mass ratio of FeS to β-FeOOH is 2:1.

[0088] Heavy metal contaminated water testing:

[0089] The prepared FeS / β-FeOOH physical mixed solution was added to the heavy metal wastewater at 5 wt.% of the mass of the polluted water body. The pH was adjusted to 10, and the mixture was stirred for 30 min until the precipitate settled naturally. The supernatant was taken for inductively coupled plasma (ICP) testing. The test results are shown in Table 1. The concentrations of each heavy metal were higher than the national standards.

[0090] Soil remediation test:

[0091] The prepared FeS / β-FeOOH composite material was added to the heavy metal contaminated soil at 5 wt.% of the contaminated soil mass. The characteristics of the heavy metal contaminated soil are shown in Table 2. The composite material was thoroughly mixed with the soil, and the pH was measured at 15 points using the S-type sampling method to ensure that the soil pH was within 11. The soil remediation effect is shown in Table 3. It can be seen that the remediation effect of heavy metal ions is less than 10%.

[0092] Table 1. ICP Results of Industrial Wastewater Detection

[0093]

[0094] Table 2. Characteristics of Soil Pollution Before Treatment

[0095] parameter Instance values ​​of contaminated soil Test methods Soil type clay loam soil USDA Texture Classification Method <![CDATA[Pb + Total amount 850mg / kg Aqua regia digestion-ICP-MS <![CDATA[Cd 2+ Total amount 35mg / kg Aqua regia digestion-ICP-MS Total As(V) 120mg / kg <![CDATA[HNO3-HF digestion-HG-AFS]]> Total Cr(VI) 180mg / kg Alkali digestion-UV spectrophotometry

[0096] Table 3 Comparison of Soil Remediation Effects

[0097]

[0098] In summary, this invention successfully exposed the highly active crystal plane of FeS(112) through an alkaline etching process, and on this basis, achieved lattice-matched bonding between it and β-FeOOH. Figure 2 a-2c HRTEM) ultimately forms a triple synergistic mechanism: First, interfacial bonding imparts oxidation inhibition function; unsaturated Fe atoms on the FeS(112) crystal plane interact with hydroxyl groups in β-FeOOH to form Fe-O-Fe covalent bonds, which is verified by characterization ( Figure 3 According to XPS results, this structure can reduce the oxidation rate of the material by 80%; secondly, it achieves the directional enrichment effect of active sites, by utilizing the selective nucleation characteristics of β-FeOOH on the FeS(112) crystal plane. Figure 2 The results of e-2hmapping significantly improved the concentration of reactive sites, ultimately increasing the reduction efficiency of Cr(VI) by 2.3 times (data in Table 1). It also achieved deep removal of Pb, Cd, Cr(VI), and As(V), with a repair efficiency far exceeding that of the comparative examples (especially Comparative Example 3). Thirdly, the heterojunction interface constructs an efficient electron transfer channel. β-FeOOH acts as an electron acceptor, rapidly receiving electrons transferred from the FeS(112) crystal plane through Fe-O-Fe covalent bonds, forming a stable and efficient reduction pathway. Table 1 data shows that the heavy metal removal rate of the heterojunction structure prepared in this scheme is 2.3 times that of the physically mixed material (Comparative Example 3). Simultaneously, relying on this electron transfer process, the oxidation behavior of FeS itself is effectively suppressed, and its oxidation inactivation rate is reduced by 80% ( Figure 3 Furthermore, as shown in Tables 1 and 3, the pH of the system environment also has a significant impact on the treatment effect when this heterojunction composite material is used to treat water or soil contaminated with heavy metals (Comparative Example 2).

[0099] This solution provides an efficient, universal, and long-lasting approach for the treatment of heavy metal contamination in industrial wastewater and polluted soil.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite material based on FeS(112) / β-FeOOH, characterized in that, Includes the following steps: S1: Iron salt and organic sulfide were dissolved in an alcohol solvent and subjected to a hydrothermal reaction under an inert atmosphere. After the reaction was completed, the mixture was centrifuged and washed to obtain a hexagonal FeS nanosheet precursor dominated by the 112 crystal plane. S2: The FeS nanosheet precursor is dispersed in an alkaline solution, and the pH value of the final product is adjusted to 9~12 by adjusting the content of the alkaline solution. The mixture is stirred and centrifuged at a constant temperature to obtain the FeS (112) / β-FeOOH heterojunction composite material. The organic sulfide is selected from one or more of divalent sulfides and high-valent sulfides; The divalent sulfides include thiols, thioethers, disulfides, polysulfides, and cyclic sulfides, and the high-valent sulfides include sulfones and sulfonic acids.

2. The preparation method according to claim 1, characterized in that, The iron salt and organic sulfide are in a molar ratio of 1:2 to 1:5; the alkaline solution concentration is 0.5 to 2 M.

3. The preparation method according to claim 1, characterized in that, The iron salt is selected from one or more of ferric nitrate, ferric sulfate, and ferric chloride; The alcohol solvent is selected from one or more of ethylene glycol, methanol, propanol, and glycerol.

4. The preparation method according to claim 1, characterized in that, The alkaline solution is selected from one or more aqueous solutions of NaOH, Na2CO3, and Ca(OH)2.

5. The preparation method according to claim 1, characterized in that, The conditions for the hydrothermal reaction are: 150~300℃, reaction time 2~6 hours; The conditions for constant temperature stirring are: stirring at 50~80℃ for 4~8 hours.

6. A composite material based on FeS(112) / β-FeOOH prepared by the preparation method according to any one of claims 1-5.

7. The application of the FeS(112) / β-FeOOH based composite material as described in claim 6 in the remediation of heavy metal-contaminated water bodies, characterized in that, The FeS(112) / β-FeOOH composite material was added to the water body polluted by heavy metals, stirred and mixed until the pH value was 9~12, and then separated by sedimentation.

8. The application according to claim 7, characterized in that, The heavy metals include Pb. 2+ Cd 2+ The composite material contains one or more of As(V) and Cr(VI); the addition ratio of the composite material is 0.1 wt.%-10 wt.%.

9. The application of the FeS(112) / β-FeOOH based composite material as described in claim 7 in the remediation of heavy metal contaminated soil, characterized in that, The composite material based on FeS (112) / β-FeOOH was added to the heavy metal contaminated soil in a certain proportion, mixed evenly, and the soil pH was tested to ensure that the soil environment pH value was within the range of 9 to 12.

10. The application according to claim 9, characterized in that, The heavy metal includes Pb. 2+ Cd 2+ One or more of As(V) and Cr(VI); The composite material is added in a proportion of 0.1 wt.% to 10 wt.%.

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