Composite material for remediation of heavy metal pollutants and preparation method and application thereof

Abstract

The present application belongs to the field of environmental management materials, and relates to a composite material for heavy metal pollutant remediation and a preparation method and application thereof. In the prior art, modified Shish Mine can remove arsenic and cadmium simultaneously, but the removal capacity for cadmium is still weak, and the single sulfur-modified zero-valent iron-based material has low reactivity and selectivity. The present application provides a composite material for heavy metal pollutant remediation, which comprises Shish Mine and sulfur-doped zero-valent iron, and the mass ratio of the two is 0.05-10:1, which can simultaneously remove heavy metal pollutants arsenic, cadmium and lead, and the adsorption capacity for cadmium and lead is increased. The present application also provides a preparation method of the composite material, which comprises ball milling elemental sulfur and zero-valent iron to obtain sulfur-doped zero-valent iron, and then ball milling the sulfur-doped zero-valent iron with Shish Mine to obtain the composite material for heavy metal pollutant remediation. The ball milling modification method is simple, efficient and pollution-free. In addition, the present application also provides an application of the composite material for heavy metal pollutant remediation in remediation of arsenic, cadmium and lead heavy metal pollution environment.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation materials technology, specifically relating to composite materials for the remediation of heavy metal pollutants, their preparation methods, and applications. Background Technology

[0002] Human activities such as mineral mining, smelting, and industrial waste disposal have led to widespread heavy metal pollution in soils globally. Lead, cadmium, and arsenic are among the most hazardous heavy metals, widely distributed and highly toxic, ranking first, eighth, and second respectively on the priority pollutant list. They can be transferred to surface water and groundwater through rainfall, deposition, and surface runoff. Consequently, heavy metals in the soil come into contact with plant roots. Considering the non-degradable nature of heavy metals, they accumulate in the food chain and are transferred to humans and animals through biomagnification, posing serious health risks. Lead and cadmium have significantly different chemical properties from arsenic, and their stability is a challenge. Therefore, there is an urgent need to develop feasible remediation technologies for soils contaminated with combined lead, cadmium, and arsenic contamination.

[0003] Among numerous remediation techniques, chemical stabilization has achieved varying degrees of success and gained widespread acceptance. Common stabilizing materials include limestone, biochar, phosphate compounds, and iron-containing materials. Schielene mineral is a naturally occurring iron-containing mineral commonly found in acidic mine drainage. Schielene mineral is a poorly crystallized, metastable secondary ferric hydroxysulfate mineral with a structure containing a large amount of -OH and SO4 groups. 2- With active functional groups, it has a highly efficient passivation ability for arsenic and can be used for the efficient passivation of arsenic in polluted water and soil. However, Schiele minerals cannot be used for the passivation of the heavy metal cadmium. In fact, using them in soil remediation processes may even increase the bioactivity of cadmium. This is mainly because Schiele minerals release sulfate ions during application, which causes a decrease in the pH of the solution, resulting in a significant increase in the mobility of cadmium. Studies have shown that when pH < 5.0, the adsorption of cadmium is almost completely inhibited. Existing technologies involve modifying Scheringer's mineral to simultaneously remove arsenic and cadmium. For example, Chinese invention patent application publication number CN115678560A, filed on November 8, 2022, entitled "A Mixed Iron Mineral for Simultaneous Remediation of Arsenic and Cadmium Heavy Metal Pollution and its Preparation Method and Application," discloses a method for preparing the mixed iron mineral, including preparing a ferrous sulfate solution of a certain concentration and adjusting it to an acidic pH; adding a certain amount of hydrogen peroxide under continuous stirring to initiate the reaction; subsequently adjusting the pH of the solution to neutral and continuing stirring; separating the formed precipitate, and drying it to obtain the mixed iron mineral for simultaneously remediating arsenic and cadmium heavy metal pollution. This mixed iron mineral, with Scheringer's mineral and ferrous sulfate as its main components, can simultaneously passivate arsenic and cadmium heavy metals in polluted water and soil, but its maximum adsorption capacity for cadmium remains low, reaching only 15 mg / g.

[0004] Zero-valent iron (ZVI) refers to the elemental form of iron in its lowest oxidation state (+0 valence). It is a pure metallic iron that has attracted widespread attention from researchers due to its environmental friendliness, non-toxicity, low cost, abundance, and strong reducing properties, and is increasingly valued in the field of water treatment. Although ZVI technology has been widely applied, it also has significant drawbacks. For example, nano-sized ZVI has a large specific surface area and high reactivity, but it is prone to aggregation, oxidation, and poor selectivity; its preparation process is complex, expensive, and difficult to store. Micron-sized iron is easy to prepare and store, but it has poor reactivity and low utilization. In recent years, single heteroatoms (sulfur, nitrogen, phosphorus) and transition metals have been commonly used to modify ZVI-based materials, as they have gained widespread attention due to their advantages such as improved electron transport, enhanced hydrophobicity, and catalytic performance. However, the reactivity and selectivity of single-sulfur-modified ZVI-based materials remain relatively low.

[0005] Previous studies have mainly focused on the removal of single heavy metals by remediation materials, neglecting the fact that multiple metals are ubiquitous in the environment. Therefore, it is necessary to develop materials that can simultaneously and effectively remove different types of heavy metals from soil, and overcome the difficulties in the simultaneous stabilization of lead, cadmium, and arsenic, as well as the problems of easy passivation of single zero-valent iron surfaces and poor adsorption performance of aging products. Summary of the Invention

[0006] 1. The problem to be solved While modified Schiele minerals in existing technologies can simultaneously remove arsenic and cadmium, their cadmium removal capacity remains relatively weak. Furthermore, existing technologies using single-sulfur modified zero-valent iron-based materials are prone to surface passivation and aging, resulting in low reactivity and selectivity for heavy metal pollutant removal. This application provides a composite material for heavy metal pollutant remediation with increased reactivity and selectivity, capable of simultaneously removing heavy metal pollutants arsenic, cadmium, and lead, and exhibiting increased adsorption capacity for cadmium and lead.

[0007] This application also provides a method for preparing composite materials for the remediation of heavy metal pollutants, which involves ball milling and mixing Schering minerals and sulfur-doped zero-valent iron. The method is simple, green, and efficient.

[0008] In addition, this application also provides the application of composite materials for the remediation of heavy metal pollutants in the remediation of environments contaminated with arsenic, cadmium, and lead.

[0009] 2. Technical Solution To achieve the above objectives, the provided technical solution is as follows: A composite material for the remediation of heavy metal pollutants comprises Schöndorfite and sulfur-doped zero-valent iron, wherein the mass ratio of Schöndorfite to sulfur-doped zero-valent iron is 0.05 to 10:1.

[0010] Sulfur-modified zero-valent iron (S-ZVI) is a modified material whose properties are improved by introducing sulfur into zero-valent iron (ZVI).

[0011] Preferably, the Fe / S molar ratio of the Schiele mineral is 5.7.

[0012] Furthermore, the molar ratio of S / Fe in the sulfur-doped zero-valent iron is 0.25~0.3.

[0013] A method for preparing composite materials for the remediation of heavy metal pollutants includes the following steps: Elemental sulfur and zero-valent iron are ball-milled and mixed, wherein the molar ratio of S / Fe in the elemental sulfur and zero-valent iron is 0.25~0.3, to obtain sulfur-doped zero-valent iron; Schiele mineral and sulfur-doped zero-valent iron are ball-milled and mixed to obtain a composite material for the remediation of heavy metal pollutants, wherein the mass ratio of Schiele mineral to sulfur-doped zero-valent iron is 0.05~10:1.

[0014] The composite material used for the remediation of heavy metal pollutants is a Schiele mineral / sulfur-doped zero-valent iron composite material.

[0015] Furthermore, the elemental sulfur is micron-sized elemental sulfur powder; the zero-valent iron is micron-sized elemental iron powder.

[0016] Preferably, the particle size of the micron-sized elemental iron powder is 70 mesh to 100 mesh.

[0017] Furthermore, the ball milling material ratio is 4~20:1.

[0018] Furthermore, the ball milling is carried out using a planetary ball mill, with a milling speed of 300 rpm to 600 rpm and a milling time of 3 h to 5 h.

[0019] Furthermore, the grinding medium is agate grinding beads, and the diameter of the agate grinding beads is 3 mm to 10 mm.

[0020] Furthermore, the agate grinding beads include agate grinding bead A, agate grinding bead B, and agate grinding bead C. The diameter of agate grinding bead A is 10.0 mm to 10.2 mm, the diameter of agate grinding bead B is 5.0 mm to 5.2 mm, and the diameter of agate grinding bead C is 3.0 mm to 3.2 mm.

[0021] Furthermore, the mass ratio of the agate grinding ball A, agate grinding ball B, and agate grinding ball C is 1:3:6.

[0022] Application of composite materials for the remediation of heavy metal pollutants, application of the composite materials for the remediation of heavy metal pollutants in the remediation of heavy metal polluted environments, or application of the composite materials for the remediation of heavy metal pollutants prepared by the method in the remediation of heavy metal polluted environments; wherein the heavy metal is one or more of arsenic, cadmium and lead.

[0023] Preferably, the application also includes selecting a single composite material remediation agent for heavy metal pollutant remediation, or using it in combination with other passivating agents, based on the actual pollution status of the soil and water, to achieve a more efficient treatment effect.

[0024] 3. Beneficial effects Compared with existing known technologies, the technical solution provided by this invention has the following beneficial effects: (1) The composite material for heavy metal pollutant remediation of the present invention comprises Schöndorfite and sulfur-doped zero-valent iron, wherein the mass ratio of Schöndorfite to sulfur-doped zero-valent iron is 0.05~10:1. The composite material for heavy metal pollutant remediation, namely Schöndorfite / sulfur-doped zero-valent iron composite material, can simultaneously solidify heavy metal anions and cations in the environment, and has the ability to simultaneously remove multiple heavy metals such as arsenic, cadmium, and lead. Moreover, the adsorption capacity for cadmium and lead is increased, mainly due to the synergistic effect of the two in terms of structure and reaction mechanism. The arsenic removal mechanism of Schöndorfite mainly includes: ① electrostatic adsorption: Schöndorfite is an iron(III) oxyhydroxyl compound with high specific surface area and abundant hydroxyl groups. The surface is positively charged and can effectively remove arsenic through electrostatic adsorption; ② surface complexation: the surface hydroxyl groups form complexes with arsenic; ③ sulfate ligand exchange. The heavy metal removal mechanism of sulfur-doped zero-valent iron includes: ① electrostatic adsorption; ② surface complexation. Sulfur doping improves the conductivity and reactivity of zero-valent iron, which is beneficial to electron migration and interfacial reaction; the sulfur element itself can also form metal sulfide precipitates with heavy metals, which are highly stable. The composite material for the remediation of heavy metal pollutants formed by combining Scheringer minerals with sulfur-doped zero-valent iron exhibits a more pronounced lamellar structure, rich pore structure, and increased specific surface area. Furthermore, due to the presence of Scheringer minerals, the surface is rougher, generating more active sites, further enhancing reactivity and electron transfer capacity. At the same time, it inhibits the passivation of the zero-valent iron surface and improves its service life.

[0025] (2) The preparation method of the composite material for heavy metal pollutant remediation of the present invention involves preparing sulfur-doped zero-valent iron material by ball milling elemental sulfur powder and zero-valent iron. This is a green and efficient material modification method. The ball milling process has high-energy impact and shear force, which can promote the uniform doping of sulfur atoms on the iron surface or the formation of Fe–S bonds (such as FeS, FeS2, etc.), avoiding the agglomeration or uneven reaction caused by simple mixing, and improving the conductivity and electron donor capacity of the material. Ball milling can break zero-valent iron particles and form more surface defects and active sites, which is beneficial to the adsorption and reaction of heavy metals. The molar ratio of S / Fe in elemental sulfur and zero-valent iron is 0.25~0.3. Sulfur-doped zero-valent iron (S-ZVI) has a shell-core structure, with zero-valent iron (ZVI) as the core and FeSx as the shell. The zero-valent iron is the actual active component, and the shell plays an accelerating and auxiliary role. Previous studies have found that if the S / Fe ratio is too small, the S doping effect will be poor, and the resulting sulfur-doped zero-valent iron will be not much different from actual zero-valent iron. If the S / Fe ratio is too large, FeSx will become denser, reducing the chance of zero-valent iron reacting with the external environment. By ball milling and mixing Scheringer minerals with sulfur-doped zero-valent iron at a mass ratio of 0.05 to 10:1, a composite material for heavy metal pollutant remediation is obtained. This composite material system achieves clear functional zoning, good interfacial coupling, and full utilization of synergistic mechanisms, significantly improving the simultaneous removal performance of heavy metals. The ball milling modification method is simple, easy to implement, can be mass-produced, and is efficient, pollution-free, and environmentally friendly.

[0026] (3) Application of the composite material for heavy metal pollutant remediation of the present invention, namely Schiele mineral / sulfur-doped zero-valent iron composite material, can simultaneously remediate arsenic, cadmium and lead heavy metal pollutant environment, and has a very efficient adsorption capacity for Cd(II) and Pb(II), with the fitted value of the maximum adsorption capacity as high as 146.4 mg / g and 204.9 mg / g, which is significantly higher than Schiele mineral (19.1 mg / g and 103.3 mg / g) and sulfur-doped zero-valent iron (93.4 mg / g and 158.7 mg / g). Attached Figure Description

[0027] Figure 1 Scanning electron microscope images of the Schiele mineral / sulfur-doped zero-valent iron composite material (a) and sulfur-doped zero-valent iron (b) prepared in Example 1; Figure 2 The graph shows a comparison of the adsorption of arsenic, cadmium, and lead by the Scherschner mineral / sulfur-doped zero-valent iron composite materials prepared in Examples 1-3, and by the Scherschner mineral and sulfur-doped zero-valent iron, respectively. Figure 3 The adsorption capacities of Schönbach's mineral / sulfur-doped zero-valent iron composite material, Schönbach's mineral, and sulfur-doped zero-valent iron for cadmium are shown in Example 1. Figure 4The adsorption capacities of Schönbrunnes mineral / sulfur-doped zero-valent iron composite material, Schönbrunnes mineral, and sulfur-doped zero-valent iron for lead prepared in Example 1 are shown. Figure 5 The adsorption capacities of Scherdler mineral / sulfur-doped zero-valent iron composite material, Scherdler mineral, and sulfur-doped zero-valent iron for arsenic are shown in Example 1. Figure 6 The passivation effects of Schärcher mineral / sulfur-doped zero-valent iron composite material prepared by adding 0.1% of Example 1, sulfur-doped zero-valent iron, and Schärcher mineral on arsenic (a) and lead (b). Detailed Implementation

[0028] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments.

[0029] The present application will be further described below with reference to specific embodiments.

[0030] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0032] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0033] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable. As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0034] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0035] In the following embodiments, the method for preparing Schwertmannite (Sch for short) is prior art. Referring to Chinese invention patent application publication number CN115920825 A, the invention is entitled "A method for modifying Schwertmannite and its application".

[0036] Example 1 The preparation method of the Schiele mineral / sulfur-doped zero-valent iron composite material in this embodiment includes the following steps: S1, Preparation of sulfur-doped zero-valent iron Weigh 1.6 g of elemental sulfur and 10 g of zero-valent iron and place them in a ball mill jar. The elemental sulfur is micron-sized elemental sulfur powder and the zero-valent iron is micron-sized elemental iron powder. The particle size of the micron-sized elemental iron powder is 70-100 mesh. The jar is filled with argon gas. Micron-sized elemental sulfur powder and iron powder have small particle sizes, which significantly increases the specific surface area of ​​the material. The larger the specific surface area, the larger the surface area of ​​contact between a unit mass of material and the reactants, thus significantly improving the reaction efficiency. Iron powder with a particle size range of 70-100 mesh is easier to disperse evenly in composite materials, increasing the uniformity and stability of the material.

[0037] The grinding jar was placed in a planetary ball mill, the ball milling speed was 400 rpm, the ball milling time was 4 h, and the ball milling material ratio (the mass ratio of the ball milling media to the material to be ground, i.e., the mixture of elemental sulfur powder and zero-valent iron) was 4.3:1. After ball milling, the milling media were separated using a sieve to obtain sulfur-doped zero-valent iron (S-ZVI) with an S / Fe molar ratio of 0.28 (S / Fe=0.28).

[0038] The grinding media is agate grinding beads, which include agate grinding beads A with a particle size of 10 mm, agate grinding beads B with a particle size of 5 mm, and agate grinding beads C with a particle size of 3 mm; the mass ratio of agate grinding beads A, agate grinding beads B, and agate grinding beads C is 1:3:6.

[0039] Preparation of S2, Schiele mineral / sulfur-doped zero-valent iron composite material Weigh 8 g of sulfur-doped zero-valent iron and 0.8 g of Schiele mineral and place them in a ball mill jar filled with argon gas; The grinding jar was placed in a planetary ball mill, the ball milling speed was 400 rpm, the ball milling time was 4 h, and the ball milling ratio (the mass ratio of the grinding media to the material to be ground, i.e., the mixture of sulfur-doped zero-valent iron and Schiele minerals) was 5.68:1. After ball milling, the milling media were separated using a sieve to obtain a Schlödinger mineral / sulfur-doped zero-valent iron composite material (Sch / S-ZVI), with a mass ratio of Schlödinger mineral to sulfur-doped zero-valent iron of 0.1.

[0040] The grinding media is agate grinding beads, which include agate grinding beads A with a particle size of 10 mm, agate grinding beads B with a particle size of 5 mm, and agate grinding beads C with a particle size of 3 mm; the mass ratio of agate grinding beads A, agate grinding beads B, and agate grinding beads C is 1:3:6.

[0041] The results were analyzed using sulfur-doped zero-valent iron prepared in step S1 as a control: The Schiele mineral / sulfur-doped zero-valent iron composite material obtained in this embodiment exhibits certain changes in structural composition and morphology compared to the control sulfur-doped zero-valent iron, such as... Figure 1 As shown, the control group of sulfur-doped zero-valent iron has fewer lamellar structures and a smoother surface; while the Scherbach mineral / sulfur-doped zero-valent iron composite material exhibits a more pronounced lamellar structure, and the surface is rougher due to the presence of Scherbach mineral; Scherbach mineral and sulfur-doped zero-valent iron undergo a chemical reaction during ball milling, generating more active sites.

[0042] Simultaneous ball milling of elemental sulfur, sulfur-doped zero-valent iron (S-ZVI), and Schieling minerals results in a complex reaction pathway, easily leading to structural disorder and a lack of interface control. Ball milling of the three components makes it difficult to control the final structural morphology and interface construction, often resulting in materials with uneven composition and uncontrollable properties, which is detrimental to efficient heavy metal removal. First, ball milling zero-valent iron with elemental sulfur to prepare structurally stable sulfur-doped zero-valent iron (S-ZVI), then combining it with Schieling minerals, can achieve a composite material system with clearly defined functional partitions, good interface coupling, and fully utilized synergistic mechanisms, significantly improving the simultaneous removal performance of heavy metals.

[0043] Example 2 The preparation method of the Schiele mineral / sulfur-doped zero-valent iron composite material in this embodiment includes the following steps: S1, Preparation of sulfur-doped zero-valent iron Weigh 1.6 g of elemental sulfur and 10 g of zero-valent iron and place them in a ball mill jar. The elemental sulfur is micron-sized elemental sulfur powder and the zero-valent iron is micron-sized elemental iron powder. The particle size of the micron-sized elemental iron powder is 70-100 mesh. The jar is filled with argon gas. The grinding jar was placed in a planetary ball mill, the ball milling speed was 400 rpm, the ball milling time was 4 h, and the ball milling material ratio (the mass ratio of the ball milling media to the material to be ground, i.e., the mixture of elemental sulfur powder and zero-valent iron) was 4.3:1. After ball milling, the milling media were separated using a sieve to obtain sulfur-doped zero-valent iron (S-ZVI) with an S / Fe molar ratio of 0.28 (S / Fe=0.28).

[0044] The grinding media is agate grinding beads, which include agate grinding beads A with a particle size of 10 mm, agate grinding beads B with a particle size of 5 mm, and agate grinding beads C with a particle size of 3 mm; the mass ratio of agate grinding beads A, agate grinding beads B, and agate grinding beads C is 1:3:6.

[0045] Preparation of S2, Schiele mineral / sulfur-doped zero-valent iron composite material Weigh 8 g of sulfur-doped zero-valent iron and 0.4 g of Schiele mineral and place them in a ball mill jar filled with argon gas; The grinding jar was placed in a planetary ball mill, the ball milling speed was 400 rpm, the ball milling time was 4 h, and the ball milling ratio (the mass ratio of the grinding media to the material to be ground, i.e., the mixture of sulfur-doped zero-valent iron and Schiele minerals) was 5.95:1. After ball milling, the milling media were separated using a sieve to obtain a Schlödinger mineral / sulfur-doped zero-valent iron composite material (Sch / S-ZVI), with a mass ratio of Schlödinger mineral to sulfur-doped zero-valent iron of 0.05.

[0046] The grinding media is agate grinding beads, which include agate grinding beads A with a particle size of 10 mm, agate grinding beads B with a particle size of 5 mm, and agate grinding beads C with a particle size of 3 mm; the mass ratio of agate grinding beads A, agate grinding beads B, and agate grinding beads C is 1:3:6.

[0047] Example 3 The preparation of the Schiele mineral / sulfur-doped zero-valent iron composite material in this embodiment includes the following steps: S1. Preparation of sulfur-doped zero-valent iron Weigh 1.6 g of elemental sulfur and 10 g of zero-valent iron and place them in a ball mill jar. The elemental sulfur is micron-sized elemental sulfur powder and the zero-valent iron is micron-sized elemental iron powder. The particle size of the micron-sized elemental iron powder is 70-100 mesh. The jar is filled with argon gas. The grinding jar was placed in a planetary ball mill, the ball milling speed was 400 rpm, the ball milling time was 4 h, and the ball milling material ratio (the mass ratio of the ball milling media to the material to be ground, i.e., the mixture of elemental sulfur powder and zero-valent iron) was 4.3:1. After ball milling, the milling media were separated using a sieve to obtain sulfur-doped zero-valent iron (S-ZVI) with an S / Fe molar ratio of 0.28 (S / Fe=0.28).

[0048] The grinding media is agate grinding beads, which include agate grinding beads A with a particle size of 10 mm, agate grinding beads B with a particle size of 5 mm, and agate grinding beads C with a particle size of 3 mm; the mass ratio of agate grinding beads A, agate grinding beads B, and agate grinding beads C is 1:3:6.

[0049] Preparation of S2, Schiele mineral / sulfur-doped zero-valent iron composite material Weigh 0.8 g of sulfur-doped zero-valent iron and 8 g of Schiele mineral and place them in a ball mill jar, which is filled with argon gas. The grinding jar was placed in a planetary ball mill, the ball milling speed was 400 rpm, the ball milling time was 4 h, and the ball milling ratio (the mass ratio of the grinding media to the material to be ground, i.e., the mixture of sulfur-doped zero-valent iron and Schiele minerals) was 5.68:1. After ball milling, the milling media were separated using a sieve to obtain a Schlödinger mineral / sulfur-doped zero-valent iron composite material (Sch / S-ZVI), with a mass ratio of Schlödinger mineral to sulfur-doped zero-valent iron of 10.

[0050] The grinding media is agate grinding beads, which include agate grinding beads A with a particle size of 10 mm, agate grinding beads B with a particle size of 5 mm, and agate grinding beads C with a particle size of 3 mm; the mass ratio of agate grinding beads A, agate grinding beads B, and agate grinding beads C is 1:3:6.

[0051] Example 4 The application of the Schöndorfite / sulfur-doped zero-valent iron composite material in this embodiment, and the adsorption of As(III), Cd(II) and Pb(II) by the Schöndorfite / sulfur-doped zero-valent iron composite material, includes the following steps: Accurately weigh 0.02 g of the Schönbrunné mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 (Sch / S-ZVI = 0.1), the Schönbrunné mineral / sulfur-doped zero-valent iron composite material obtained in Example 2 (Sch / S-ZVI = 0.05), and the Schönbrunné mineral / sulfur-doped zero-valent iron composite material obtained in Example 3 (Sch / S-ZVI = 10), and add them sequentially to a 50 mg / L, 50 mL As(III) solution, a 50 mg / L, 50 mL Cd(II) solution, and a 150 mg / L, 50 mL Pb(II) solution. Adjust the pH of the solution to 6.0, then place it in a shaker at 28 ℃ and 180 rpm. Maintain the pH of the reaction system at 6.0 ± 0.1 using 0.01 M (0.01 mol / L) HNO3 and 0.01 M (0.01 mol / L) NaOH. After h, samples were passed through a 0.45 μm filter membrane and the contents of As(III), Cd(II), and Pb(II) were determined. The final results are shown in the figure. Figure 2 .

[0052] Comparative Example 1 The application of Schiele minerals in this comparative example, and the adsorption of As(III), Cd(II), and Pb(II) by Schiele minerals, includes the following steps: Accurately weigh 0.02 g of Schiele mineral and add it sequentially to a 50 mg / L (50 mL) As(III) solution, a 50 mg / L (50 mL) Cd(II) solution, and a 150 mg / L (50 mL) Pb(II) solution. Adjust the pH of the solution to 6.0, then place it in a shaker at 28 ℃ and 180 rpm. Maintain the pH of the reaction system at 6.0 ± 0.1 using 0.01 M (0.01 mol / L) HNO3 and 0.01 M (0.01 mol / L) NaOH. After 18 h, take a sample, filter it through a 0.45 μm filter membrane, and determine the contents of As(III), Cd(II), and Pb(II). The final results are shown in the figure. Figure 2 .

[0053] Comparative Example 2 The application of sulfur-doped zero-valent iron in this comparative example, and the adsorption of As(III), Cd(II) and Pb(II) by sulfur-doped zero-valent iron, follows basically the same procedure as in Comparative Example 1, except that: The Schiele mineral was replaced with sulfur-doped zero-valent iron prepared in step S1 of Example 1; the final results obtained from the analysis are shown below. Figure 2 .

[0054] Example 4, Comparative Example 1 and Comparative Example 2 Results Analysis: In order to analyze the concentration of heavy metal ions in the solution, the contents of As(III), Cd(II) and Pb(II) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The Schöndorfite / sulfur-doped zero-valent iron composite material (Sch / S-ZVI = 0.1) obtained in Example 1 showed adsorption capacities of 43.8 mg / g for As(III), 36.5 mg / g for Cd(II), and 57.6 mg / g for Pb(II), respectively. The Schöndorfite / sulfur-doped zero-valent iron composite material (Sch / S-ZVI = 0.05) obtained in Example 2 showed adsorption capacities of 36.6 mg / g for As(III), 37.2 mg / g for Cd(II), and 55.3 mg / g for Pb(II), respectively. The Schöndorfite / sulfur-doped zero-valent iron composite material (Sch / S-ZVI = 10) obtained in Example 3 showed adsorption capacities of 35.3 mg / g for As(III), 32.3 mg / g for Cd(II), and 48.7 mg / g for Pb(II), respectively, which were higher than the adsorption capacities of the Schöndorfite group in Comparative Example 1 (30.0 mg / g for As(III), Cd(II), and Pb(II)). The adsorption capacities of As(III), Cd(II), and Pb(II) in the Scheringer mineral / sulfur-doped zero-valent iron composite material were compared with those in the comparative example 2 (15.8 mg / g, 20.2 mg / g, and 32.9 mg / g, respectively). The Scheringer mineral / sulfur-doped zero-valent iron composite material showed adsorption capacities of more than 5 times for Cd(II) and more than 2.5 times for Pb(II) compared to the Scheringer mineral group, and more than 2 times for As(III).

[0055] Example 5 The application of the Schöndorfite / sulfur-doped zero-valent iron composite material in this embodiment, and the maximum adsorption capacity of the Schöndorfite / sulfur-doped zero-valent iron composite material for Cd(II), includes the following steps: Accurately weigh 0.02 g of the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 and add it sequentially to 50 mL of gradient Cd(II)-containing solutions (10 mg / L, 15 mg / L, 30 mg / L, 40 mg / L, 50 mg / L). Adjust the pH of the solution to 6.0, then place it in a shaker at 28 ℃ and 180 rpm. Maintain the pH of the reaction system at 6.0 ± 0.1 using 0.01 M (0.01 mol / L) HNO3 and 0.01 M (0.01 mol / L) NaOH. After 24 h, take a sample, filter it through a 0.45 μm filter membrane, and determine the Cd(II) content. The final results are shown in the figure. Figure 3 .

[0056] The adsorption isotherm model was used to fit the adsorption isotherm data of Schöndorfite / sulfur-doped zero-valent iron composite material, Schöndorfite, and sulfur-doped zero-valent iron. The model formula is as follows:

[0057] In the formula, C e (mg / L) represents the concentrations of remaining As(III), Cd(II), and Pb(II) in the solution when adsorption reaches equilibrium; q e (mg / g) represents the amount of adsorption at which adsorption reaches equilibrium; q m (mg / g) represents the maximum adsorption capacity fitted by the Langmuir adsorption isotherm; K L (L / mg) represents the adsorption constant of the Langmuir model.

[0058] Comparative Example 3 The application of Scherbach's mineral in this comparative example, the maximum adsorption capacity of Scherbach's mineral for Cd(II), and the operation steps are basically the same as in Example 5, except that the Scherbach's mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 is replaced with Scherbach's mineral. The final results obtained from the analysis are shown in [see figure]. Figure 3 .

[0059] Comparative Example 4 The application of sulfur-doped zero-valent iron in this comparative example, the maximum adsorption capacity of sulfur-doped zero-valent iron for Cd(II), and the operation steps are basically the same as in Example 5, except that the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 is replaced with sulfur-doped zero-valent iron. The final results obtained from the analysis are shown in […]. Figure 3 .

[0060] Analysis of the results of Example 5, Comparative Example 3, and Comparative Example 4: The fitting results show that the Langmuir adsorption isotherm model can better describe the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1, the Schiele mineral, and the sulfur-doped zero-valent iron pair with Cd(II) (… Figure 3 The adsorption of ) and the correlation coefficient R 2 All values ​​are greater than 0.9. The Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 has a very high adsorption capacity for Cd(II), with a maximum adsorption capacity fitting value as high as 146.4 mg / g, which is significantly higher than the maximum adsorption capacity of Schiele mineral for Cd(II) of 19.1 mg / g and the maximum adsorption capacity of sulfur-doped zero-valent iron for Cd(II) of 93.4 mg / g.

[0061] Example 6 The application of the Schöndorfite / sulfur-doped zero-valent iron composite material in this embodiment, and the maximum adsorption capacity of the Schöndorfite / sulfur-doped zero-valent iron composite material for Pb(II), includes the following steps: Accurately weigh 0.02 g of the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 and add it sequentially to 50 mL of gradient Pb(II)-containing solutions (10 mg / L, 40 mg / L, 60 mg / L, 80 mg / L, 100 mg / L). Adjust the pH of the solution to 6.0, then place it in a shaker at 28 ℃ and 180 rpm. Maintain the pH of the reaction system at 6.0 ± 0.1 using 0.01 M (0.01 mol / L) HNO3 and 0.01 M (0.01 mol / L) NaOH. After 24 h, take a sample, filter it through a 0.45 μm filter membrane, and determine the Pb(II) content. The final results are shown in the figure. Figure 4 .

[0062] Comparative Example 5 The application of Scherbach's mineral in this comparative example, the maximum adsorption capacity of Scherbach's mineral for Pb(II), and the operation steps are basically the same as in Example 6, except that the Scherbach's mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 is replaced with Scherbach's mineral. The final results obtained from the analysis are shown in [see figure]. Figure 4 .

[0063] Comparative Example 6 The application of sulfur-doped zero-valent iron in this comparative example, the maximum adsorption capacity of sulfur-doped zero-valent iron for Pb(II), and the operation steps are basically the same as in Example 6, except that the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 is replaced with sulfur-doped zero-valent iron. The final results obtained from the analysis are shown in […]. Figure 4 .

[0064] Analysis of the results of Example 6, Comparative Example 5, and Comparative Example 6: The fitting results show that the Langmuir adsorption isotherm model can better describe the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1, the Schiele mineral, and the sulfur-doped zero-valent iron pair with Pb(II). Figure 4 The adsorption of ) and the correlation coefficient R 2 All values ​​are greater than 0.9. The Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 has a high adsorption capacity for Pb(II), with a maximum adsorption capacity fitting value as high as 204.9 mg / g, which is higher than the maximum adsorption capacity of Schiele mineral for Pb(II) of 103.3 mg / g and the maximum adsorption capacity of sulfur-doped zero-valent iron for Pb(II) of 158.7 mg / g.

[0065] Example 7 The application of the Schöndorfite / sulfur-doped zero-valent iron composite material in this embodiment, and the maximum adsorption capacity of the Schöndorfite / sulfur-doped zero-valent iron composite material for As(III), includes the following steps: Accurately weigh 0.02 g of the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 and add it sequentially to 50 mL of gradient As(III)-containing solutions (10 mg / L, 15 mg / L, 20 mg / L, 30 mg / L, 50 mg / L, 60 mg / L, 70 mg / L). Adjust the pH of the solution to 6.0, and then place it in a shaker at 28 ℃ and 180 rpm. Maintain the pH of the reaction system at 6.0 ± 0.1 using 0.01 M (i.e., 0.01 mol / L) HNO3 and 0.01 M (i.e., 0.01 mol / L) NaOH. After 24 h, take a sample, filter it through a 0.45 μm filter membrane, and determine the As(III) content. The final results are shown in the figure. Figure 5 .

[0066] Comparative Example 7 The application of Scherbach's mineral in this comparative example, the maximum adsorption capacity of Scherbach's mineral for As(III), and the operation steps are basically the same as in Example 7, except that the Scherbach's mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 is replaced with Scherbach's mineral. The final results obtained from the analysis are shown in [see figure]. Figure 5 .

[0067] Comparative Example 8 The application of sulfur-doped zero-valent iron in this comparative example, the maximum adsorption capacity of sulfur-doped zero-valent iron for As(III), and the operation steps are basically the same as in Example 7, except that the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 is replaced with sulfur-doped zero-valent iron. The final results obtained from the analysis are shown in […]. Figure 5 .

[0068] Analysis of the results of Example 7, Comparative Example 7, and Comparative Example 8: The fitting results show that the Langmuir adsorption isotherm model can better describe the Schiele mineral / sulfur-doped zero-valent iron composite material, Schiele mineral, and sulfur-doped zero-valent iron on As(III) obtained in Example 1. Figure 5 The adsorption of ) and the correlation coefficient R 2 All values ​​were greater than 0.9. Although the maximum arsenic adsorption capacity of the Scheres mineral / sulfur-doped zero-valent iron composite (47.7 mg / g) was lower than that of Scheres mineral (74.7 mg / g), it was higher than that of sulfur-doped zero-valent iron (33.8 mg / g).

[0069] In conjunction with Example 4, Comparative Example 1, Comparative Example 2, and Figure 2 It can be seen that the adsorption amounts measured in all experiments are lower than the corresponding Langmuir q. m The value is in line with theoretical expectations. mThis represents the limiting adsorption capacity of a material under saturated conditions, and typically requires high concentrations to approach this value. The Schlödinger mineral / sulfur-doped zero-valent iron composite material (Sch / S-ZVI = 0.1) exhibits an adsorption capacity of 43.8 mg / g for As(III), close to its qi value. m (47.7 mg / g) indicates that it is close to saturation at a concentration of 50 mg / L, because its high affinity (large Langmuir constant b), high specific surface area, and more exposed active sites make the adsorption process easier; the adsorption capacity of Schiele mineral for As(III) at 30 mg / g is much lower than q. m (74.7 mg / g) indicates that a higher concentration is required to reach saturation; thus, it can be seen that the Schiele mineral / sulfur-doped zero-valent iron composite material has a better adsorption effect on low concentrations of As(III), and its adsorption capacity is higher than that of the Schiele mineral group.

[0070] Example 8 This embodiment provides the application of the Schereschewsky mineral / sulfur-doped zero-valent iron composite material prepared in Example 1 in the remediation of arsenic and lead contaminated soil, including the following steps: Add 0.1% of the Schlödermite / sulfur-doped zero-valent iron composite material (Sch / S-ZVI = 0.1) prepared in Example 1 to the arsenic- and lead-contaminated soil and stir well; add deionized water to maintain the soil moisture content at 50%; cure the soil and take samples on the 7th day of curing. Allow the soil samples to air dry naturally, grind them, and store them through a 10-mesh sieve. The Wenzel fractional extraction method was used to study the content of non-specifically adsorbed arsenic in soil. Specifically, 1 g of soil was weighed into a 50 mL centrifuge tube, and the mixture was shaken with 25 mL of 0.05 M ammonium sulfate solution at 25 ± 3 °C for 4 h. The mixture was then centrifuged at 10,000 rpm for 10 min, and the supernatant was filtered through a 0.45 μm filter to obtain the content of non-specifically adsorbed arsenic in the soil. The BCR method was used to extract the content of weakly acidic lead in soil. Specifically, 0.5 g of soil was weighed into a 50 mL centrifuge tube, and the mixture was shaken with 20 mL of 0.11 M acetic acid solution at 25 ± 3 °C for 16 h. The mixture was then centrifuged at 10,000 rpm for 10 min, and the supernatant was filtered through a 0.45 μm filter to obtain the content of weakly acidic lead in the soil. The arsenic and lead contents were determined by ICP-MS, and the final results are shown below. Figure 6 .

[0071] Comparative Example 9 The application of Scherdmann mineral in the remediation of arsenic and lead contaminated soil provided in this comparative example is basically the same as in Example 8, except that Scherdmann mineral is used to replace the Scherdmann mineral / sulfur-doped zero-valent iron composite material prepared in Example 1. The final results obtained from the analysis are shown in […]. Figure 6 .

[0072] Comparative Example 10 The application of sulfur-doped zero-valent iron in the remediation of arsenic and lead contaminated soil provided in this comparative example is basically the same as in Example 8, except that sulfur-doped zero-valent iron is used instead of the Schiele mineral / sulfur-doped zero-valent iron composite material prepared in Example 1. The final results obtained from the analysis are shown in […]. Figure 6 .

[0073] Analysis of the results of Examples 8, 9, and 10: Non-specific adsorbed arsenic, also known as weakly adsorbed arsenic, mainly consists of arsenic adsorbed on the surface of soil particles. It has strong bioavailability and migration ability, and can be absorbed by plants through ion exchange into the soil solution. Weakly acidic lead, also known as weakly acid-extractable lead, is a chemical form of lead present in the environment, referring to lead that can be extracted under weakly acidic conditions. This type of lead usually exists in an exchangeable or carbonate-bound state, and is a form with high bioavailability in the environment, easily absorbed by plants or microorganisms. Testing showed that after remediating arsenic- and lead-contaminated soil, the Schiele mineral / sulfur-doped zero-valent iron composite material obtained in Example 1 reduced the content of non-specific adsorbed arsenic from 6.9 mg / kg to 2.4 mg / kg, with a remediation rate of 65%; while the content of weakly acid-extractable lead decreased from 58.6 mg / kg to 9.9 mg / kg, with a remediation rate of 83%. After remediation of arsenic- and lead-contaminated soil, Schiele minerals reduced the non-specifically adsorbed arsenic content to 2.5 mg / kg, achieving a remediation rate of 63%; the weakly acid-extractable lead content decreased to 19.2 mg / kg, achieving a remediation rate of 67%. After remediation of arsenic- and lead-contaminated soil, sulfur-doped zero-valent iron reduced the non-specifically adsorbed arsenic content to 4.6 mg / kg, achieving a remediation rate of 33%; the weakly acid-extractable lead content decreased to 17.6 mg / kg, achieving a remediation rate of 69%. This indicates that after remediation with the Schiele minerals / sulfur-doped zero-valent iron composite material, the arsenic contaminant content in the soil remained at a low level, while the lead contaminant content was significantly lower than that of the sulfur-doped zero-valent iron group and the Schiele mineral group.

[0074] (Because the cadmium content in the soil already met the standards before remediation, it could not be measured, but by...) Figure 2 and Figure 3 It can be seen that the adsorption capacity of the Schiele mineral / sulfur-doped zero-valent iron composite material for cadmium is significantly higher than that of the Schiele mineral group and the sulfur-doped zero-valent iron group. In summary, this invention utilizes ball milling modification to obtain a composite material for the remediation of heavy metal pollutants, namely, a Scheringer mineral / sulfur-doped zero-valent iron composite material, which can be used to treat environments co-polluted with arsenic, cadmium, and lead. Compared to sulfur-doped zero-valent iron, the Scheringer mineral / sulfur-doped zero-valent iron composite material exhibits a more pronounced lamellar structure, and its surface is rougher due to the presence of Scheringer mineral. During ball milling, Scheringer mineral and sulfur-doped zero-valent iron undergo a chemical reaction, generating more active sites. Scheringer mineral possesses a unique amorphous structure and is an excellent passivating agent for arsenic pollution in soil. After ball milling modification, the Scheringer mineral / sulfur-doped zero-valent iron composite material can overcome the opposite chemical behaviors of heavy metals arsenic and cadmium / lead, achieving simultaneous passivation and remediation of arsenic, cadmium, and lead, while also increasing the passivation and remediation of cadmium and lead, effectively solving the problems in existing technologies.

[0075] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing composite materials for the remediation of heavy metal pollutants, characterized in that: Includes the following steps: Elemental sulfur and zero-valent iron are ball-milled and mixed, wherein the S / Fe molar ratio of elemental sulfur to zero-valent iron is 0.25~0.3, to obtain sulfur-doped zero-valent iron; Schiele mineral and sulfur-doped zero-valent iron are ball-milled and mixed to obtain a composite material for the remediation of heavy metal pollutants, wherein the mass ratio of Schiele mineral to sulfur-doped zero-valent iron is 0.05~10:

1.

2. The method for preparing the composite material for heavy metal pollutant remediation according to claim 1, characterized in that: The elemental sulfur is micron-sized elemental sulfur powder; the zero-valent iron is micron-sized elemental iron powder.

3. The method for preparing the composite material for heavy metal pollutant remediation according to claim 1, characterized in that: The ball milling material ratio is 4~20:

1.

4. The method for preparing the composite material for heavy metal pollutant remediation according to claim 3, characterized in that: The ball milling is carried out using a planetary ball mill, with a milling speed of 300 rpm to 600 rpm and a milling time of 3 h to 5 h.

5. The method for preparing the composite material for heavy metal pollutant remediation according to claim 4, characterized in that: The grinding media is agate grinding beads, and the diameter of the agate grinding beads is 3 mm to 10 mm.

6. The method for preparing the composite material for heavy metal pollutant remediation according to claim 5, characterized in that: The agate grinding beads include agate grinding bead A, agate grinding bead B, and agate grinding bead C. The diameter of agate grinding bead A is 10.0 mm to 10.2 mm, the diameter of agate grinding bead B is 5.0 mm to 5.2 mm, and the diameter of agate grinding bead C is 3.0 mm to 3.2 mm.

7. The method for preparing the composite material for heavy metal pollutant remediation according to claim 6, characterized in that: The mass ratio of the agate grinding beads A, B, and C is 1:3:

6.

8. A composite material for the remediation of heavy metal pollutants, characterized in that: It is prepared by the method described in any one of claims 1-7.

9. The application of composite materials for the remediation of heavy metal pollutants, characterized in that: The application of the composite material for remediation of heavy metal pollutants according to claim 8 in the remediation of heavy metal polluted environments; wherein the heavy metal is one or more of arsenic, cadmium and lead.

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