CuS rich in sulfur defects, and a preparation method and application thereof

Abstract

The application relates to the technical field of inorganic materials, in particular to a sulfur-defect-rich CuS and a preparation method and application thereof. The preparation method comprises the following steps: S1, mixing CuS, a dispersing agent and an organic sulfur source in the presence of a solvent to form a slurry; S2, performing wet ball milling on the slurry, performing solid-liquid separation, taking the solid, washing and drying to obtain a precursor; S3, annealing the precursor under vacuum to obtain the sulfur-defect-rich CuS; wherein the wet ball milling process adopts intermittent ball milling at a rotating speed of 400-600 r / min for 2-4 h. Through the above wet ball milling, sulfur source induction and vacuum heat treatment steps, the sulfur-defect-rich CuS can efficiently remove selenium in wastewater.

Description

Technical Field

[0001] This invention relates to the field of inorganic materials technology, and in particular to a sulfur-rich defect CuS, its preparation method, and its applications. Background Technology

[0002] Currently, common treatment technologies for selenium-containing wastewater include chemical precipitation, adsorption, ion exchange, electrochemical reduction, and biological methods. Chemical precipitation is simple to operate and low in cost, but it consumes large amounts of reagents and produces a significant amount of selenium-containing sludge. Adsorption offers some selectivity, but its adsorption capacity is limited and regeneration is difficult. Biological methods, while environmentally friendly, suffer from slow reaction rates, long start-up periods, and are highly dependent on environmental conditions. Electrochemical and photocatalytic methods can achieve deep removal, but they are characterized by high energy consumption and complex equipment. In summary, existing selenium removal technologies generally suffer from high energy consumption, complex operation, or low treatment rates, making it difficult to meet the needs of industrial-scale application.

[0003] In wastewater treatment, heterogeneous reactions refer to reactions between solid materials and pollutants in solution. These reactions typically occur on the surface of solid catalysts, and the reaction rate is strongly influenced by the catalyst's surface characteristics, pore structure, and defects. CuS, as a heterogeneous catalytic material, utilizes its abundant surface defects and active sites to effectively remove pollutants through electron transfer and reaction with them. Furthermore, by introducing sulfur vacancies into CuS crystals through defect engineering, its electronic structure can be effectively modulated, significantly improving electron mobility and surface reactivity. Sulfur vacancies not only act as electron enrichment centers promoting charge separation and transfer but also directly participate in redox processes as reactive sites, thereby enhancing the activation ability of pollutant molecules. High-density sulfur-vacancy CuS materials can effectively promote electron conversion reactions of molecular oxygen, hydrogen peroxide, and various inorganic or organic pollutants, exhibiting excellent removal performance for reducible pollutants such as Se(IV) and Se(VI).

[0004] However, existing CuS materials generally suffer from problems such as uneven sulfur vacancy distribution, poor structural stability, and low utilization of active sites during preparation, which limit their practical application in the treatment of selenium-containing wastewater. Therefore, it is necessary to develop a CuS-based selenium removal material with controllable structure, uniform vacancy distribution, and high stability to achieve efficient and low-cost selenium removal. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a sulfur-rich defect CuS, its preparation method, and its application.

[0006] A first aspect of the present invention provides a method for preparing sulfur-rich defective CuS, comprising the following steps:

[0007] S1. In the presence of a solvent, CuS, a dispersant, and an organic sulfur source are mixed to form a slurry;

[0008] S2. After wet ball milling the slurry, solid-liquid separation is performed, the solid is collected, washed, and dried to obtain the precursor;

[0009] S3. Anneal the precursor under vacuum conditions to obtain the final product;

[0010] The wet ball milling process involves intermittent ball milling at a rotation speed of 400-600 r / min for 2-4 hours.

[0011] This invention utilizes a synergistic process of co-ball milling with an organic sulfur source, intermittent pulsed wet ball milling, and vacuum heat treatment to construct a high-density, stable sulfur vacancy structure in CuS crystals. This significantly improves the specific surface area, conductivity, and reactivity of the material, thereby achieving efficient removal of Se(IV) / Se(VI) from selenium-containing wastewater.

[0012] In some embodiments of the present invention, in step S1, the solvent includes ethanol, deionized water, or a mixture of the two.

[0013] In some embodiments of the present invention, in step S1, the solid-liquid ratio of CuS to the solvent is 1g:1~10mL.

[0014] In some embodiments of the present invention, in step S1, the dispersant includes at least one of polyvinylpyrrolidone and polyethylene glycol.

[0015] In some embodiments of the present invention, in step S1, the dispersant accounts for 0.1 to 1 wt% of CuS, for example, 0.1 to 0.5 wt%.

[0016] In some embodiments of the present invention, in step S1, the organic sulfur source is a thermally decomposable sulfur source, including at least one of thiourea, thioacetamide, and L-cysteine.

[0017] In some embodiments of the present invention, in step S1, the organic sulfur source accounts for 0.1 to 1 wt% of CuS by mass ratio, for example 0.1 to 0.5 wt%, 0.1 to 0.4 wt%, 0.1 to 0.3 wt%, or 0.1 to 0.2 wt%.

[0018] In some embodiments of the present invention, in step S1, the mixing time is 10-60 min, for example 10-40 min, 20-40 min, or about 30 min.

[0019] In some embodiments of the present invention, in step S2, the wet ball milling is performed in a ball milling jar containing grinding balls using a planetary ball mill. Further, the grinding balls in the ball milling jar are selected from agate (or zirconium oxide) grinding balls with a diameter of 8 mm and agate (or zirconium oxide) grinding balls with a diameter of 10 mm, wherein the 8 mm diameter agate (or zirconium oxide) grinding balls account for 20% to 70% of the total grinding ball mass, and the 10 mm diameter agate (or zirconium oxide) grinding balls account for 30% to 80% of the total grinding ball mass. Further, the ball-to-powder mass ratio is 10 to 20:1, preferably 12 to 16:1, and more preferably 14:1.

[0020] In some embodiments of the present invention, in step S2, the (intermittent pulse) wet ball milling process consists of alternating high-energy ball milling stage and intermittent cooling stage, including intermittent ball milling at a rotation speed of 400-600 r / min (e.g., 500 r / min) (high-energy ball milling speed) for 2-4 hours (e.g., 3 hours). The intermittent ball milling process is to stop intermittently for 4-6 minutes (e.g., 5 minutes) after each ball milling for 10-15 minutes, and repeat this process (10-15 times) until the cumulative ball milling time equals the set ball milling time, wherein the intermediate intermittent time is included in the total ball milling time.

[0021] During ball milling, the synergistic effect of mechanical energy excitation and chemical induction by sulfur precursors promotes the formation and homogenization of sulfur vacancies in the CuS lattice. The ball milling process employs a high-energy intermittent pulse mode—high-speed (400-600 r / min) for 10-15 min, followed by a 4-6 min pause, repeated multiple times. This program, alternating between mechanical impact and cooling relaxation, facilitates lattice fracture and local rearrangement, enhancing the uniformity and depth of defect formation.

[0022] In some embodiments of the present invention, in step S2, the solid-liquid separation method includes centrifugation and filtration separation.

[0023] In some embodiments of the present invention, in step S2, the solvent used for washing is ethanol, which can remove residual organic matter or unreacted sulfur precursors.

[0024] In some embodiments of the present invention, in step S2, the drying temperature is 40~70 °C and the time is 8~16 h.

[0025] In some embodiments of the present invention, in step S3, the vacuum condition is performed in a vacuum tube furnace. Annealing under vacuum conditions can improve the stability of sulfur vacancies and reduce surface oxidation.

[0026] In some embodiments of the present invention, in step S3, the annealing is performed in a vacuum tube furnace at 10°C. -1 ~10 -4 mbar (e.g., 10) -2 The process is carried out under a vacuum of mbar, with a heating rate of 2~10 ℃ / min (e.g. 4~8 ℃ / min, 5 ℃ / min), a holding temperature of 150~350 ℃ (e.g. 200~300 ℃, 250 ℃), and a holding time of 0.5~4 h (e.g. 1~3 h, 2 h), followed by natural cooling to room temperature.

[0027] During this process, thiourea undergoes thermal decomposition, and the released sulfur atoms are redistributed on the CuS lattice surface, forming and stabilizing a high-density sulfur vacancy structure.

[0028] This invention utilizes wet ball milling and a thermally decomposable sulfur source to induce a sulfur vacancy structure in the CuS lattice, and combines this with vacuum heat treatment to achieve directional stabilization of the sulfur vacancies. The resulting copper sulfide with sulfur defects can efficiently reduce Se(IV) / Se(VI) in wastewater to elemental selenium through electron transfer mediated by sulfur vacancies, thereby achieving efficient removal of selenium from selenium-containing wastewater.

[0029] In a second aspect, the present invention provides a sulfur-rich defective CuS, which is prepared by the above-described preparation method.

[0030] The sulfur-rich defective copper sulfide material prepared by this invention has the advantages of fast reaction rate, good regeneration repeatability and environmental friendliness, and has good prospects for industrial application.

[0031] A third aspect of the present invention provides the application of the aforementioned sulfur-rich CuS in the treatment of selenium-containing wastewater.

[0032] The sulfur-rich defective copper sulfide powder of the present invention is added to selenium removal wastewater. Through the electron transfer mediated by sulfur vacancies, Se(IV) / Se(VI) is reduced to elemental selenium, thereby achieving efficient removal of selenium from the wastewater.

[0033] A fourth aspect of the present invention provides a method for treating selenium-containing wastewater, comprising contacting the aforementioned sulfur-rich CuS with the selenium-containing wastewater.

[0034] The sulfur-rich defective copper sulfide material of the present invention reduces Se(IV) / Se(VI) in wastewater to elemental selenium through electron transfer mediated by sulfur vacancies, and achieves efficient deselenization without the need for external light source, power supply or chemical oxidant.

[0035] In some embodiments of the present invention, the selenium-containing wastewater is industrial wastewater, smelting wastewater or electroplating wastewater containing Se(IV) and / or Se(VI), with a selenium concentration of 1~50 mg / L, for example 1~40 mg / L, 1~30 mg / L, 1~20 mg / L, or 1~10 mg / L.

[0036] In some embodiments of the present invention, the contact is described as stirring at room temperature.

[0037] In some embodiments of the present invention, the solid-liquid ratio of the sulfur-rich defective CuS to the selenium-containing wastewater is 0.4~2 mg:1 mL, for example, 0.4~1 mg:1 mL.

[0038] According to some embodiments of the present invention, at least the following beneficial effects are achieved:

[0039] The sulfur-defect-rich copper sulfide used in this invention is inexpensive, readily available, and environmentally friendly, requiring no complex synthesis, making it a green and economical selenium removal catalyst. This invention employs a combined process of wet ball milling and vacuum heat treatment. Mechanical stress induces defects in the CuS lattice, followed by vacuum heat treatment to stabilize sulfur vacancies, achieving deep optimization of the CuS surface structure. The preparation process is simple and efficient. Through sulfur vacancy-mediated electron transfer, Se(IV) / Se(VI) can be efficiently reduced to elemental selenium without external energy or chemical reagents, achieving rapid selenium removal from wastewater. The sulfur-defect-rich copper sulfide catalyst prepared by this invention exhibits excellent reactivity and cycle stability for selenium-containing wastewater, achieving ultrafast selenium removal rates at room temperature. It is simple to operate, has low energy consumption, and is suitable for industrial applications.

[0040] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0041] Figure 1 The image shows the XRD pattern of BM-CuS obtained in Example 1 of this invention.

[0042] Figure 2 This is a SEM image of BM-CuS obtained in Example 1 of the present invention.

[0043] Figure 3 This is the electron paramagnetic resonance spectrum of sulfur vacancy in BM-CuS obtained in Example 1 of the present invention.

[0044] Figure 4 The graph shows the removal efficiency of copper sulfide materials prepared in Example 1, Comparative Examples 1 and 2 of this invention for Se(IV) removal in selenium-removing wastewater.

[0045] Figure 5 The graph shows the recycling rate of BM-CuS obtained in Example 1 of this invention. Detailed Implementation

[0046] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0047] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0048] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0049] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0050] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0051] The design concept of this invention is to provide a method for preparing sulfur-rich defective CuS (rich in various sulfur-related defects, such as vacancies, interstitials, and antisites) by combining sulfur source induction, intermittent pulsed wet ball milling, and vacuum heat treatment, and to propose the application of this sulfur-rich defective CuS in the treatment of selenium-removing wastewater. Specifically, this invention utilizes the chemical assistance of sulfur precursors (such as thiourea) during the wet ball milling process. Through the synergistic effect of mechanical impact and chemical reaction, high-density defects and initial sulfur vacancies are induced in the CuS lattice. Subsequently, vacuum heat treatment promotes the redistribution of the thermal decomposition products of the sulfur precursor on the CuS surface, realizing the reconstruction and stabilization of sulfur vacancies. The resulting CuS material has abundant and stable sulfur vacancies. Through the electron transfer mediated by sulfur vacancies, Se(IV) / Se(VI) in wastewater can be efficiently reduced to elemental selenium under conditions of no light, no external electric field, and no chemical oxidant, thereby achieving efficient removal of selenium from selenium-removing wastewater.

[0052] To ensure that the design concept of the present invention can be clearly understood by those skilled in the art, the following examples illustrate the sulfur-rich defect CuS, its preparation method, and its application in treating selenium-removing wastewater.

[0053] Unless otherwise specified in the examples, standard conditions or conditions recommended by the manufacturer were followed. Reagents or instruments whose manufacturers are not specified are all commercially available products. All data obtained in the examples are averages from three or more replicate experiments.

[0054] Example 1

[0055] This embodiment provides a method for preparing sulfur-rich defective CuS, including the following steps:

[0056] Weigh 5 g of CuS powder and add 50 mL of ethanol (or deionized water) as the liquid medium, along with 0.5 wt% polyvinylpyrrolidone (based on CuS mass) as a dispersant. While stirring, add 0.2 wt% thiourea (based on CuS mass) as a thermally decomposable sulfur precursor and continue stirring for 30 min to ensure uniform dispersion and form a slurry. Transfer the slurry to a planetary agate ball mill jar, and prepare agate balls (a mixture of 10 mm and 8 mm diameter balls at a ball / powder mass ratio of 14:1). Use a high-energy intermittent pulsed milling mode: run at 500 r / min for 10 min, pause for 5 min to cool, and then start the next cycle, repeating this process 12 times for a total equivalent milling time of approximately 3 h. This program alternates between mechanical impact and cooling intervals, promoting the formation of high-density activation sites and initial sulfur vacancies in the CuS lattice while preventing excessive grain breakage. After milling, centrifuge to obtain the solid, and wash three times with ethanol to remove residual thiourea and organic matter. The obtained wet sample was vacuum dried at 50 °C for 12 h to obtain ball-milled precursor powder. The dried powder was placed in a vacuum tube furnace and evacuated to 10 °C. -2 mbar. The temperature was increased to 250 °C at 5 °C / min, held at this temperature for 2 h, and then naturally cooled to room temperature. During the pyrolysis process, the active sulfur atoms released by thiourea redistributed on the CuS surface, and underwent a rearrangement reaction with the defect sites induced by pulse ball milling, forming and stabilizing a high-density sulfur vacancy structure. The resulting product is designated as BM-CuS.

[0057] Figure 1 , 2 The figures show the XRD analysis results and SEM images of BM-CuS, respectively. The images show that the crystal structure of CuS is well maintained after ball milling, indicating the successful preparation of BM-CuS.

[0058] Figure 3Electron paramagnetic resonance (EPR) analysis showed that the sulfur vacancy signal intensity of BM-CuS was increased, indicating that the wet ball milling technique successfully prepared BM-CuS.

[0059] Next, 50 mg of BM-CuS was dispersed in 50 mL of a 10 mg / L Se(IV) simulated wastewater solution and the mixture was magnetically stirred at 25 °C under open air conditions. Samples were taken at 0, 10, 30, and 60 min of reaction, filtered through a 0.22 μm filter membrane, and the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0060] Figure 4 The results showed the removal rate of Se by BM-CuS at various time points. As can be seen from the figure, BM-CuS has a high efficiency in removing Se(IV), with a removal rate of about 92% within 60 min, indicating that BM-CuS has excellent catalytic reduction ability in the treatment of selenium-removed wastewater.

[0061] In addition, after the residual Se concentration was determined (i.e., after use), BM-CuS was washed, dried and then dispersed again in 50 mL of 10 mg / L Se(IV) simulated wastewater solution. The reaction was repeated 4 times under the above reaction conditions, and the residual Se concentration was recorded each time.

[0062] Figure 5 The figure shows the processing efficiency of the BM-CuS material prepared in this embodiment after four cycles of use. As can be seen from the results, after four cycles of use, the removal rate of Se by BM-CuS remains above 80%, indicating that the material has excellent recycling performance and stability.

[0063] Example 2

[0064] This embodiment provides a method for preparing sulfur-rich defective CuS, including the following steps:

[0065] Weigh 5 g of CuS powder and add 50 mL of ethanol (or deionized water) as the liquid medium, along with 0.5 wt% polyethylene glycol (based on the mass of copper sulfide) as a dispersant. While stirring, add 0.2 wt% thiourea (based on the mass of CuS) as a thermally decomposable sulfur precursor, and continue stirring for 30 min to ensure uniform dispersion and form a slurry. Transfer the slurry to a planetary agate ball mill jar, and prepare agate balls (a mixture of 10 mm and 8 mm diameter balls at a ball / powder mass ratio of 14:1). Use a high-energy intermittent pulse mode: run at 500 r / min for 10 min, pause for 5 min to cool, and then start the next cycle, repeating this process 12 times for a total equivalent milling time of approximately 3 h. This program alternates between mechanical impact and cooling intervals, promoting the formation of high-density activation sites and initial sulfur vacancies in the CuS lattice while preventing excessive grain breakage. After milling, centrifuge to obtain the solid, and wash three times with ethanol to remove residual thiourea and organic matter. The obtained wet sample was vacuum dried at 50 °C for 12 h to obtain ball-milled precursor powder. The dried powder was placed in a vacuum tube furnace and evacuated to 10 °C. -2 mbar. The temperature was increased to 250 °C at 5 °C / min, held at this temperature for 2 h, and then naturally cooled to room temperature. During the pyrolysis process, the active sulfur atoms released by thiourea redistributed on the CuS surface, and underwent a rearrangement reaction with the defect sites induced by pulse ball milling, forming and stabilizing a high-density sulfur vacancy structure. The resulting product was designated BM-CuS-1.

[0066] 50 mg BM-CuS-1 was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted magnetically at 25 °C with the bottle open and air provided. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0067] The results showed that BM-CuS-1 had a high efficiency in removing Se(IV), with a removal rate of 89% after 60 min.

[0068] Example 3

[0069] This embodiment provides a method for preparing sulfur-rich defective CuS, which is carried out in accordance with Example 1, except that a high-energy intermittent pulse mode is used: the high-speed section runs at 400 r / min for 10 min, pauses for 5 min to cool, and then starts the next cycle, which is repeated 12 times in total, with a total equivalent ball milling time of about 3 h. The material is named BM-CuS-2.

[0070] 50 mg of BM-CuS-2 was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted under magnetic stirring at 25 °C. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0071] The results showed that BM-CuS-2 achieved a Se(IV) removal rate of 88% at 60 min.

[0072] Example 4

[0073] This embodiment provides a method for preparing sulfur-rich defective CuS, which is carried out with reference to Example 1, except that: the post-processing heat treatment adopts vacuum heat treatment at a temperature of 200 °C, and the material is named BM-CuS-3.

[0074] 50 mg of BM-CuS-3 was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted under magnetic stirring at 25 °C. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0075] The results showed that BM-CuS-3 achieved a Se(IV) removal rate of 83% at 60 min.

[0076] Comparative Example 1

[0077] This comparative example provides a method for preparing sulfur-rich defective CuS, which is carried out in accordance with Example 1, except that ball milling is not performed. Specifically, it includes the following steps:

[0078] Weigh 5 g of CuS powder, add 50 mL of ethanol as the liquid medium, and add 0.5 wt% polyvinylpyrrolidone (based on the mass of CuS) as a dispersant. Add 0.2 wt% thiourea (based on the mass of CuS) while stirring, and continue stirring for 30 min to uniformly disperse it into a slurry. Centrifuge to obtain the solid, and wash three times with ethanol to remove residual thiourea and organic matter. Dry the obtained wet sample under vacuum at 50 ℃ for 12 h to obtain a dry powder. Place the dry powder in a vacuum tube furnace and evacuate to 10 °C. -2 mbar. The temperature was increased to 250 °C at a rate of 5 °C / min, held at that temperature for 2 h, and then allowed to cool naturally to room temperature.

[0079] 50 mg of unmilled CuS powder was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted with magnetic stirring at 25 °C. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0080] Figure 4 The results show that the Se(IV) removal rate of un-ball-milled CuS within 60 min is less than 20%, indicating that the synergistic effect of ball milling and vacuum heat treatment plays a crucial role in improving the reactivity of CuS with sulfur-rich defects. These results demonstrate that the ball milling process is a key step in inducing lattice defects and sulfur vacancies; mechanical stress can break the CuS lattice, generating a high density of active sites. Without ball milling, the CuS surface lacks sufficient sulfur vacancies and active sites, resulting in weak electron transfer ability and low removal rate.

[0081] Comparative Example 2

[0082] This comparative example provides a method for preparing sulfur-rich defective CuS, comprising the following steps:

[0083] 5g of raw CuS was placed in an agate jar, and agate balls were added at a ball-to-powder ratio of 14:1. The mixture was ball-milled at 400 r / min for 3 hours to obtain ordinary ground CuS powder. That is, this sample was prepared using a dry mechanical ball milling method.

[0084] 50 mg of the powder was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted magnetically at 25 °C with the bottle open and air provided. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0085] Figure 4 The results showed that conventional dry ball milling of CuS achieved a Se(IV) removal rate of approximately 46% within 60 min, which improved the treatment effect to some extent, but the effect was not as significant as that of BM-CuS.

[0086] Comparative Example 3

[0087] Add an appropriate amount of sodium sulfide solution to 50 mL of a 10 mg / L Se(IV) solution to achieve a sodium sulfide concentration of 0.1 mol / L, and keep stirring. After the reaction is complete, remove the generated selenium precipitate by filtration and determine the residual Se concentration.

[0088] The results showed that sodium sulfide removed approximately 48% of Se(IV) after 60 minutes of reaction, but the large amount of sulfide precipitates generated during the reaction process may affect subsequent treatment or recycling. In contrast, the BM-CuS material prepared in Example 1 achieved a Se(IV) removal rate of 92% within the same reaction time, without the need for external oxidants, with no additional pollutants, and can be recycled, demonstrating significant advantages.

[0089] Comparative Example 4

[0090] This comparative example provides a method for preparing sulfur-rich defective CuS, which is carried out with reference to Example 1, except that no sulfur source is added and the resulting material is named BM-CuS-4.

[0091] 50 mg of BM-CuS-4 was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted under magnetic stirring at 25 °C. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0092] The results showed that BM-CuS-4 achieved a Se(IV) removal rate of 41% at 60 min.

[0093] Comparative Example 5

[0094] This comparative example provides a method for preparing sulfur-rich defective CuS, which is carried out with reference to Example 1, except that sodium sulfide is added as a sulfur source, and the resulting material is named BM-CuS-5.

[0095] 50 mg of BM-CuS-5 was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted under magnetic stirring at 25 °C. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0096] The results showed that BM-CuS-5 achieved a Se(IV) removal rate of 56% at 60 min.

[0097] Comparative Example 6

[0098] This comparative example provides a method for preparing sulfur-rich defective CuS, which is carried out with reference to Example 1, except that no dispersant is added and the material is named BM-CuS-6.

[0099] 50 mg of BM-CuS-6 was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted under magnetic stirring at 25 °C. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0100] The results showed that BM-CuS-6 achieved a Se(IV) removal rate of 67% at 60 min.

[0101] Comparative Example 7

[0102] This comparative example provides a method for preparing sulfur-rich defective CuS, which is carried out with reference to Example 1, except that the post-processing heat treatment is carried out by heating in an air atmosphere, and the material is named BM-CuS-7.

[0103] 50 mg of BM-CuS-7 was dispersed in 50 mL of 10 mg / L Se(IV) simulated wastewater solution and reacted under magnetic stirring at 25 °C. Samples were taken for analysis at 0, 10, 30 and 60 min of reaction. After filtration through a 0.22 μm filter membrane, the residual Se concentration was determined by atomic absorption spectrometry (AAS).

[0104] The results showed that BM-CuS-7 achieved a Se(IV) removal rate of 67% at 60 min.

[0105] The above description, in conjunction with the embodiments, provides a detailed explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing CuS rich in sulfur defects, characterized in that, The method comprises the following steps: S1, mixing CuS, a dispersant and an organic sulfur source in the presence of a solvent to form a slurry; S2, after wet ball milling the slurry, performing solid-liquid separation, taking the solid, washing and drying to obtain a precursor; S3, annealing the precursor under vacuum conditions to obtain the sulfur-defect-rich CuS; The wet ball milling process adopts an intermittent ball milling at a rotation speed of 400-600 r / min for 2-4 h; The solvent comprises ethanol, deionized water or a mixture of the two; The dispersant comprises at least one of polyvinylpyrrolidone and polyethylene glycol; The organic sulfur source comprises at least one of thiourea, thioacetamide and L-cysteine; the organic sulfur source accounts for 0.1-1 wt% of CuS in terms of mass ratio; The annealing temperature is 150-350 ℃.

2. The production method according to claim 1, characterized by, The solid-liquid ratio of CuS to the solvent is 1 g:1-10 mL.

3. The method of claim 1, wherein, The intermittent ball milling process is to stop for 4-6 min after ball milling for 10-15 min, and the cycle is repeated until the cumulative ball milling time is equal to the set ball milling time, wherein the intermediate intermittent time is included in the total ball milling time.

4. The method of claim 1, wherein, The annealing rate is 2-10 ℃ / min; and / or, the annealing holding time is 0.5-4 h.

5. A sulfur-deficient CuS characterized in that, The sulfur-defect-rich CuS is prepared by the preparation method of any one of claims 1-4.

6. The sulfur-defect-rich CuS of claim 5 is applied in treating selenium-containing wastewater.

7. A method of treating wastewater containing selenium, characterized by, The method comprises contacting the sulfur-defect-rich CuS of claim 5 with the selenium-containing wastewater.

8. Use according to claim 6 or method according to claim 7, characterized in that, The solid-liquid ratio of the sulfur-defect-rich CuS to the selenium-containing wastewater is 0.4-2 mg:1 mL.

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