Copper-iron sulfide bimetallic catalyst, preparation method and application thereof

Abstract

The application relates to the technical field of organic pollutant degradation, and discloses a preparation method of a copper iron sulfide bimetallic catalyst, which comprises the following steps: under anaerobic conditions, copper chloride and iron powder are added into an acid buffer solution, a sodium sulfide solution is added after the mixture is uniformly mixed, and the copper iron sulfide bimetallic catalyst is obtained after reaction and filtration; the molar ratio of the copper chloride and the iron powder ranges from 0.3 to 1.3; and the molar ratio of the sodium sulfide and the iron powder ranges from 0.046 to 0.46. The copper iron sulfide bimetallic catalyst containing the main component CuFeS2 is prepared by exploring the feeding molar ratio of copper, iron and sulfur. The catalytic performance of the copper iron sulfide bimetallic catalyst prepared by the method is effectively improved. After the copper iron sulfide bimetallic catalyst is used to treat organic wastewater, the removal efficiency of the organic matter is maintained stable, and there is no leaching of metal Cu and Fe. The catalyst has the advantages of low treatment cost, simple operation condition and high efficiency, and provides a new method for low-carbon treatment of organic wastewater.

Description

Technical Field

[0001] This invention belongs to the field of organic pollutant degradation technology, and more specifically, relates to a copper-iron sulfide bimetallic catalyst and its preparation method. Background Technology

[0002] The treatment of organic wastewater remains a challenging area of ​​international research. Human activities have led to the presence of various antibiotics in groundwater and surface water, with sulfonamides being particularly prevalent and present at high concentrations. Researchers using the risk entropy method have shown that sulfonamides are among the antibiotics posing the highest ecological risk to urban groundwater and contributing the largest proportion of the threat. Furthermore, the increasing volume of domestic waste, combined with rainfall and the moisture content of the waste itself, results in 10%–30% of landfill leachate being generated, threatening the ecological environment and human health. For these organic wastewaters, biological treatment methods are time-consuming and inefficient, while physical methods suffer from secondary pollution. Therefore, economical and efficient treatment methods for organic wastewater are urgently needed.

[0003] The Fenton process is considered one of the most promising methods for treating organic wastewater. Catalytic activation of the oxidant generates free radicals with high redox potentials, which can rapidly oxidize most organic pollutants. Persulfate and hydrogen peroxide are common oxidants in the Fenton reaction, but they suffer from problems such as significant secondary pollution, high operating costs, and difficulties in storage and transportation. Conversely, molecular oxygen is considered an ideal oxidant, possessing advantages such as being green, pollution-free, naturally non-toxic, and widely available. However, oxygen has a low redox potential and is difficult to activate; therefore, utilizing economical and efficient methods to activate oxygen is of great significance.

[0004] Molecular oxygen activation is a process of continuous adsorption and dissociation of O2 on the catalyst surface, and it is a key step in catalytic reactions. Previous studies have shown that natural minerals have an activating effect on O2, such as the ·O2 generated by the activation reaction of O2 by pyrite. - Pyrite reacts with hydrogen ions to generate H₂O₂, and then reacts with Fe(II) dissolved in pyrite via a Fenton reaction to generate ·OH. However, due to the slow-release effect of pyrite, its apparent oxygen activation efficiency is low. Furthermore, the auto-oxidation behavior of pyrite causes a sharp increase in the concentration of Fe and sulfides in the system, leading to secondary pollution. Therefore, seeking an economical and efficient modification method for pyrite to improve its ability to activate molecular oxygen is of great significance for the low-consumption and high-efficiency degradation of practical organic wastewater.

[0005] Referring to the structure of natural minerals, constructing catalysts with better catalytic effects using simple and low-cost preparation methods is a new approach for treating organic wastewater. This invention provides a one-step synthesis of copper-iron sulfide bimetallic catalysts, which are used to activate oxygen to degrade organic matter, and has the advantages of being simple, inexpensive, and environmentally friendly. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for synthesizing a copper-iron sulfide bimetallic catalyst and activating oxygen to treat organic wastewater. By optimizing the molar ratio of iron, sulfur, and copper, the catalytic performance of the copper-iron sulfide bimetallic catalyst is effectively improved. Furthermore, the synthesized copper-iron sulfide bimetallic catalyst is used to activate oxygen and degrade organic pollutants. This method is applicable to the treatment of antibiotic-containing wastewater and other organic wastewater such as landfill leachate, with significantly improved removal efficiency. It offers advantages such as low treatment cost, simple and efficient operation, and provides a new approach to organic wastewater treatment.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a copper-iron sulfide bimetallic catalyst is provided, the method comprising:

[0008] Under anaerobic conditions, copper chloride and iron powder are added to an acidic buffer solution, mixed evenly, and then sodium sulfide solution is added. After reaction, the mixture is filtered to obtain the copper sulfide-iron bimetallic catalyst. The molar ratio of copper chloride to iron powder is in the range of 0.3 to 1.3, and the molar ratio of sodium sulfide to iron powder is in the range of 0.046 to 0.46.

[0009] As a preferred embodiment of the present invention, the acidic buffer solution is one of acetic acid-sodium acetate solution, citric acid-sodium citrate solution, and formic acid-sodium formate solution, and the acidic buffer solution is used after deoxygenation; preferably, the acetic acid-sodium acetate solution is used, and the mass-to-volume ratio of sodium acetate to acetic acid is 45-50 g / mL.

[0010] As a preferred embodiment of the present invention, the pH of the acidic buffer solution is 5.6 to 7, preferably 6.0 to 6.4.

[0011] As a preferred embodiment of the present invention, the reaction time is 8 to 15 hours.

[0012] As a preferred embodiment of the present invention, the purity of copper chloride and iron powder is greater than or equal to 99%.

[0013] In another aspect of the invention, a copper-iron sulfide bimetallic catalyst prepared by the preparation method described in the first aspect of the invention comprises CuFeS2.

[0014] In another aspect of the invention, the application of the copper-iron sulfide bimetallic catalyst as described in the second aspect of the invention in the treatment of organic wastewater.

[0015] As a preferred embodiment of the present invention, the organic wastewater is wastewater containing aromatic compounds.

[0016] As a preferred embodiment of the present invention, the application includes the following steps:

[0017] (1) Prepare the organic wastewater to be treated;

[0018] (2) Weigh the copper-iron sulfide bimetallic catalyst and add it to the organic wastewater in step (1), and stir it in an air atmosphere; wherein the dosage of the copper-iron sulfide bimetallic catalyst is 1 to 10 g / L.

[0019] (3) After treatment, the sediment in the wastewater system is filtered and recycled for reuse.

[0020] As a preferred embodiment of the present invention, the application includes: filling the copper-iron sulfide bimetallic catalyst into a column reactor, and pumping the organic wastewater to be treated from the bottom of the column for treatment after fully aeration.

[0021] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0022] (1) The copper-iron sulfide bimetallic catalyst provided by this invention, compared with the prior art, utilizes specific molar ratios of iron, copper, and sulfur, controlling the Cu / Fe molar ratio to 0.3–1.3, the S / Fe molar ratio to 0.046–0.46, and the pH of the acidic buffer solution to 5.6–7. This synthesized copper-iron sulfide bimetallic catalyst effectively enhances the catalytic activity of copper-iron based materials. The sulfidated copper-iron bimetallic catalyst is particularly useful for treating organic wastewater and degrading organic pollutants, exhibiting significantly better treatment results than unsulfidated copper-iron materials. The copper-iron sulfide bimetallic catalyst synthesized by this invention is low-cost, simple to synthesize (no calcination or other high-temperature and high-pressure treatments required), and utilizes it to activate oxygen for treating organic wastewater, resulting in low energy consumption, environmental friendliness, and no secondary pollution.

[0023] (2) The copper-iron sulfide bimetallic catalyst material obtained by the method of the present invention is applied to the treatment of organic wastewater. It has low treatment cost, simple operating conditions, high treatment efficiency, and the water quality after treatment meets the relevant national standards, providing a new way to remove organic pollutants from water. Using this invention, 99% of sulfamethoxazole (SMX) with an initial concentration of 150 mg / L, a typical pharmaceutical wastewater containing mainly representative organic pollutants, can be degraded. Simultaneously, COD can be reduced to within 100 mg / L as required by the Class I standard of the "Integrated Wastewater Discharge Standard" (GB8978-1996). For landfill leachate ultrafiltration effluent (Raw) wastewater with a COD concentration of 318 mg / L, the COD removal efficiency can reach up to 37% (removing approximately 118.6 mg / L), the TOC removal efficiency is 32% (removing 37.3 mg / L), and the color is significantly reduced. For landfill leachate biochemical effluent (Raw2) wastewater with a COD concentration of 232 mg / L, the COD removal efficiency can reach up to 55% (removing approximately 129.3 mg / L), the TOC removal efficiency is 35% (removing 36.2 mg / L), and the color is significantly reduced. The treated COD is lower than the requirement of no more than 200 mg / L stipulated in the secondary standard of the "Integrated Wastewater Discharge Standard" (GB8978-1996), thus achieving the purpose of harmlessness. Compared with similar inventions, it has the advantages of high efficiency and greenness.

[0024] (3) The copper-iron sulfide bimetallic catalyst material prepared based on the present invention was applied to a continuous flow reactor. Under the condition of continuous operation for 36 hours and material replacement every 12 hours, the degradation efficiency of SMX was stable, and the operating conditions were simple and the treatment efficiency was high, with the treatment efficiency being greater than 85%. This shows that the copper-iron sulfide bimetallic catalyst can not only catalyze the activation of oxygen to degrade organic matter, but also has efficient and stable catalytic performance and the preparation method is green and simple, with great potential for practical application.

[0025] In summary, this invention successfully developed a catalyst based on a natural mineral structure. The copper-iron sulfide bimetallic catalyst synthesized based on this invention effectively solves the above-mentioned problems in treating recalcitrant organic pollutants by utilizing its synergistic effect with oxygen. It is suitable for the deep treatment of recalcitrant organic wastewater containing sulfamethoxazole and other recalcitrant organic pollutants, as well as complex organic wastewater and landfill leachate. It can degrade organic pollutants and remove TOC, degrade COD and reduce the color of actual wastewater, facilitating the resource utilization of industrial wastewater. Attached Figure Description

[0026] Figure 1 The present invention provides an example of a method for synthesizing a copper-iron sulfide bimetallic catalyst and a process flow diagram for treating organic wastewater.

[0027] Figure 2The images shown are SEM-EDS (Scanning Electron Microscope-Energy Dispersive Spectrometer) and TEM-Mapping (Ransmission Electron Microscopy) test results of the copper-iron sulfide bimetallic catalyst in this embodiment of the invention. Figure 2 In the image, a and b are SEM images of FeCu-S and Fe-Cu, respectively. Figure 2 The cg in the figure represents the elemental mapping diagrams of Cu, Fe, S and O in the sulfidated copper-iron bimetallic material of experimental group 1. Figure 2 The hl diagrams in the diagrams represent the elemental mappings of Cu, Fe, S, and O elements in the control group Fe-Cu of experimental group 1.

[0028] Figure 3 The middle section shows the sample composition and structure test of the experimental group and control group in Example 1; Figure 3 In the figure, 'a' represents the XRD patterns of the experimental and control group samples. Figure 3 In the graph, b represents the O2-TPD analysis data. Figure 3 In the figure, c represents the degradation efficiency of SMX by the control groups 1-4 and the experimental group 1. Figure 3 In the figure, d represents the degradation efficiency of SMX in experimental group 1 with an initial concentration of 10–150 mg / L;

[0029] Figure 4 This is an example of the effect of different dosages of copper-iron sulfide bimetallic catalysts and different pH conditions on the degradation efficiency of SMX and the data on Cu and Fe leaching. Figure 4 a, b, and c in the figure represent the effects of different amounts of copper-iron sulfide bimetallic catalyst added on the degradation efficiency of SMX. Figure 4 In the figure, d, e, and f represent the effect of changing pH conditions on the degradation efficiency of SMX.

[0030] Figure 5 The degradation data of SMX by the iron-copper bimetallic catalysts exemplified in Examples 3 and 4 of this invention are shown. Figure 5 In the figure, 'a' represents the degradation efficiency data of SMX by iron-copper bimetallic catalysts prepared with different S / Fe molar ratios; where Figure 5 In the figure, b represents the reaction rate of the iron-copper bimetallic catalyst prepared with different S / Fe molar ratios for the degradation of SMX and the leaching data of Cu ions in the system after the reaction. Figure 5 In the figure, c represents the degradation efficiency data of SMX by iron-copper bimetallic catalysts prepared with different Cu / Fe molar ratios; Figure 5In the figure, d represents the reaction rate of SMX degradation by iron-copper bimetallic catalysts prepared with different Cu / Fe molar ratios and the leaching of Cu ions in the system after the reaction.

[0031] Figure 6 Example 5 of the present invention illustrates the removal efficiency of copper-iron sulfide bimetallic catalyst for COD and TOC in ultrafiltration water from landfill leachate, and compares the color and three-dimensional fluorescence (EEM) before and after the reaction. Figure 6 In this context, 'a' represents the removal efficiency of copper-iron sulfide bimetallic catalysts prepared with different FeCu-S dosages for COD and TOC removal from ultrafiltration water of landfill leachate. Figure 6 In the figure, b is a comparison of COD and TOC removal after the landfill leachate ultrafiltration effluent was treated with FeCu-S catalyst for 10 hours; Raw2 is the landfill leachate ultrafiltration effluent; Raw2-10 is the landfill leachate ultrafiltration effluent treated with FeCu-S catalyst for 10 hours. Figure 6 In the figure, c represents the colorimetric diagram of the landfill leachate ultrafiltration effluent before and after treatment with FeCu-S catalyst; Figure 6 In the figure, d represents a comparison of three-dimensional fluorescence (EEM) images of landfill leachate ultrafiltration water treated with FeCu-S catalyst;

[0032] Figure 7 Example 6 of the present invention illustrates the removal efficiency of copper-iron sulfide bimetallic catalyst for COD and TOC in biochemical effluent from landfill leachate, as well as a comparison of color and three-dimensional fluorescence (EEM) before and after the reaction. Figure 7 In the figure, 'a' represents the removal efficiency of COD and TOC in ultrafiltration water of landfill leachate prepared with different FeCu-S dosages of copper iron sulfide bimetallic catalysts, 'Raw2' represents the biochemical effluent of landfill leachate, and 'Raw2-10' represents the biochemical effluent of landfill leachate treated with FeCu-S catalyst for 10 hours. Figure 7 In this context, b represents the removal efficiency of COD and TOC in the ultrafiltration effluent of landfill leachate after treatment with FeCu-S catalyst. Figure 7 In the figure, c represents the colorimetric diagram of the landfill leachate ultrafiltration effluent before and after treatment with FeCu-S catalyst; Figure 7 In the figure, d represents a comparison of three-dimensional fluorescence (EEM) images of landfill leachate ultrafiltration water treated with FeCu-S catalyst;

[0033] Figure 8 This is an example of the continuous flow experimental apparatus for the copper-iron sulfide bimetallic catalyst of the present invention and its long-term operation. Figure 8 The left side shows the long-term operating data of the continuous flow experiment of the copper-iron sulfide bimetallic catalyst. Figure 8 The right side shows a diagram of a continuous flow experimental setup for a copper-iron sulfide bimetallic catalyst.

[0034] Figure 9The degradation data of the copper-iron sulfide bimetallic catalyst and the control group are shown in Example 8 of this invention. Figure 9 In the figure, a and b represent the concentration data of TOC on the solid surface and in the liquid after 120 min of reaction, respectively. Figure 9 In this context, c represents the desorption ratio of SMX; Figure 9 In this context, d represents the degradation efficiency of SMX under a nitrogen atmosphere. Figure 9 The species e is an EPR (Electron Paramagnetic Resonance) map; Figure 9 The data for quenching experiments with 500 mg / L cationic superoxide dismutase (CAT), 1 mol / L methanol (MeOH), 1 mol / L tert-butanol (TBA), 1 mol / L furfuryl alcohol (FFA), 10 μmol / L p-benzoquinone (BQ), and a blank control (CK) were obtained. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0036] In the embodiments of the present invention, the preparation of the copper-iron sulfide bimetallic catalyst is as follows:

[0037] Prepare an acidic buffer solution, for example, by using one or more of the following: acetic acid-sodium acetate solution, citric acid-sodium citrate solution, and formic acid-sodium formate solution, and control the pH of the acidic buffer solution to be 5.6-7, preferably 6.0-6.4.

[0038] Preparation of acetic acid-sodium acetate solution: Dissolve sodium acetate in ultrapure water, then adjust the pH of the solution to 5.6-7, preferably 6.0-6.4, with acetic acid, wherein the ratio of sodium acetate to acetic acid is 45-50 g / mL; then aerate the solution with nitrogen to remove oxygen from the solution.

[0039] Synthesis of copper-iron sulfide bimetallic catalyst: Copper chloride and reduced iron powder were added according to a Cu to Fe molar ratio of 0.3–1.3 and a S to Fe molar ratio of 0.046–0.46. After the raw materials were mixed and dissolved, sodium sulfide was added, and the mixture was stirred at room temperature for 10–15 hours using a magnetic stirrer at a stirring speed of 200–300 rpm. After the reaction, the mixture was allowed to stand, and after the precipitate settled, the supernatant was poured off, retaining only the precipitate.

[0040] Purification: The solid was separated twice by vacuum filtration and washed three times each with ultrapure water and anhydrous ethanol. The washed solid was then dried in a freeze dryer to remove solvent or moisture, and then stored in a vacuum bag under vacuum for later use.

[0041] In the embodiments of the present invention, the application of copper-iron sulfide bimetallic catalysts in organic matter treatment, especially in organic wastewater treatment or the mineralization of organic matter in organic wastewater, mainly takes two forms:

[0042] Firstly, it specifically includes the following steps:

[0043] (1) Pour the organic wastewater to be treated into a beaker and prepare the wastewater to be tested with a concentration of 10-150 mg / L;

[0044] (2) Weigh the copper-iron sulfide bimetallic catalyst and add it to the mixture in step (1), and stir it in an air atmosphere for 0 to 600 min; wherein the dosage of the copper-iron sulfide bimetallic catalyst is 1 to 10 g / L.

[0045] (3) After treatment, filter and recover the sediment in the wastewater system and reuse it.

[0046] Secondly, it specifically includes the following steps:

[0047] The copper-iron sulfide bimetallic catalyst is packed into a column reactor. The organic wastewater to be treated is fully aerated and then pumped in from the bottom of the column. The mass ratio of quartz sand to FeCu-S is (7.5–9.5):1. For example, the hydraulic retention time is 2 hours, the flow rate is 0.05 mL / min, and the volume per pore (PV) is 6 mL. The catalyst can be replaced after 12 hours of continuous treatment.

[0048] In embodiments of the present invention, the concentration of SMX was determined by high-performance liquid chromatography, for example, using a mobile phase of 0.1% (v / v) acetic acid and acetonitrile (v / v = 40%:60%) at a flow rate of 0.6 mL / min. Total organic carbon (TOC) was used to measure the degree of mineralization of organic matter, and TOC was measured using a total organic carbon / nitrogen analyzer. Changes in CODcr concentration in landfill leachate were measured according to the industry standard "Water Quality - Determination of Chemical Oxygen Demand - Dichromate Method" (HJ 828-2017).

[0049] like Figure 1 The operation flowchart shows: For example, to prepare a 50 mg / L SMX solution using sulfamethoxazole solid, take 100 mL and place it in a 250 mL Erlenmeyer flask, then adjust the initial pH to 7.0, for example, using 0.1 M H2SO4 and 0.1 M NaOH. Prepare the catalyst as described in the above examples, and prepare catalytic systems with different concentrations.

[0050] Under air atmosphere, the conical flask was placed on a magnetic stirrer for reaction, and the concentrations of SMX and TOC were measured within 0–120 min. Each time, 1 mL of sample was taken, filtered through a 0.22 μm filter membrane, and 50 μL of methanol was added to terminate the reaction. The concentration of SMX was immediately measured using a high-performance liquid chromatograph after the sample was thoroughly mixed.

[0051]

[0052] In the above formula, η is the removal rate. When calculating the SMX removal rate, C0 is the SMX concentration in the initial system (containing SMX wastewater); C is the SMX concentration in the system treated with catalyst for 0-120 min in different experimental or control groups.

[0053] The following are specific embodiments.

[0054] Example 1

[0055] Different experimental and control groups were prepared using the above method, as detailed below:

[0056] Table 1. Copper-iron sulfide bimetallic catalysts and example numbers

[0057]

[0058] Preparation of acetic acid-sodium acetate solution: Dissolve sodium acetate in ultrapure water, then adjust the pH of the solution to 6.2 with acetic acid to prepare an acetic acid-sodium acetate solution with a specific concentration range; then aerate the solution with nitrogen for at least 30 minutes to remove oxygen from the solution.

[0059] Synthesis of copper-iron sulfide bimetallic catalyst: Copper chloride and reduced iron powder were added according to the molar ratio in Table 1. After the raw materials were mixed and dissolved, sodium sulfide was added, and then the mixture was stirred at room temperature for 12 hours at a stirring speed of 300 rpm using a magnetic stirrer. After the reaction, the mixture was allowed to stand for 30 minutes. After the precipitate settled, the supernatant was poured off, and only the precipitate was retained. Experimental group 1 with sample composition FeCu-S, control group 1 with sample composition Fe-S, control group 2 with sample composition Fe-Cu, control group 3 with sample composition Cu-S, and control group 4 with pure reduced iron powder were prepared.

[0060] Purification: The solid was separated twice by vacuum filtration and washed three times each with ultrapure water and anhydrous ethanol. The washed solid was then dried in a freeze dryer for 12 hours, and then vacuum-sealed in a bag for later use. Table 1 below lists the samples and example numbers for each experimental group.

[0061] Based on the samples from Example 1, the concentration of FeCu-S catalyst in experimental group 1 was set at 1.0 g / L, and the concentrations of Cu-S, Fe-S, Fe-Cu, and Fe catalysts in the control group were all set at 1.0 g / L. 0System. Under air atmosphere, the conical flask was placed on a magnetic stirrer for reaction, and the concentrations of SMX and TOC were measured within 0–120 min. Each time, 1 mL of sample was taken, filtered through a 0.22 μm filter membrane, and 50 μL of methanol was added to terminate the reaction. The concentration of SMX was immediately measured using high-performance liquid chromatography (HPLC) after the sample was thoroughly mixed.

[0062] Figure 2 In the figure, 'a' represents the SEM and TEM images of control group 2; Figure 2 In the figure, b represents the SEM and TEM images of experimental group 1; Figure 2 (cg) is the TEM-Mapping image of the sulfided copper-iron bimetallic material in Experiment 1. The main element in the image is Cu, with Fe and S elements uniformly doped in the middle. Figure 2 (hl) is the TEM-Mapping image of the sulfidated copper-iron bimetallic material in control group 2. The main element in the image is Cu, while Fe and O are mainly distributed at the particle edges.

[0063] like Figure 2 As shown, the morphology of the copper-iron bimetallic catalyst with sulfide is as follows: the unsulfided material exhibits a rod-like structure with a slightly rough surface. In contrast, the sulfided FeCu-S material has a granular surface with a smaller particle size, suggesting a larger specific surface area, more contact sites with organic matter and oxygen, and thus stronger catalytic performance. Furthermore, the control group shows that the catalytically active Cu sites are encased within Fe and O elements, which is detrimental to the contact and activation of oxygen with the Cu sites.

[0064] Figure 3 The middle section shows the sample composition and structure test based on the experimental and control groups in Example 1, where... Figure 3 In the example, 'a' represents the XRD pattern of each sample. Figure 3 b in the figure represents O2-TPD analysis; Figure 3 In the figure, c represents the degradation efficiency of SMX by the control groups 1-4 and the experimental group 1. Figure 3 In the figure, d represents the degradation efficiency of SMX in experimental group 1 with an initial concentration of 10-150 mg / L.

[0065] from Figure 3 As shown in section 'a', the FeCu-S catalyst in experimental group 1 consists of CuFeS2, CuO, FeO, and Cu, respectively. Control group 2 has a similar structure. Control group 4 mainly consists of Cu2S and Cu9S8, while control group 1 mainly consists of Fe. 0 Therefore, it can be inferred that the addition of S did not increase the content of elemental Cu.

[0066] Figure 3The results in b show that the FeCu-S group had a higher surface oxygen content compared to the control group, where α represents physically adsorbed oxygen, β represents chemisorbed oxygen, and γ represents lattice oxygen. Figure 3 Integrating the peak area in Figure b, the results showed that the oxygen on the surface of the FeCu-S group was 39 times that of the control group, indicating that the FeCu-S group had the ability to store oxygen.

[0067] Figure 3 The results showed that the FeCu-S group had a significantly higher removal efficiency for SMX than the control group, removing almost all SMX within 10 minutes. The removal efficiency of the control group was poor. This demonstrates that the addition of sulfur significantly promotes the catalytic or adsorption performance of the material.

[0068] Example 2

[0069] like Figure 1 The operation flowchart shows that an experimental group with different sample addition amount and solution pH than experimental group 1 in Example 1 was set up to demonstrate that the catalyst material of the present invention has degradation performance in both metal ion status and a wide pH reaction range.

[0070] Experiment on the dosage of copper-iron bimetallic catalyst: The concentration of SMX was set at 50 mg / L, and the concentration of copper-iron sulfide bimetallic material was set at 0.1–1.5 g / L. The initial pH was then adjusted to 7.0 with 0.1 M H₂SO₄ and 0.1 M NaOH. The conical flask was placed on a magnetic stirrer for reaction under air atmosphere. 2 mL samples were taken at intervals of 0–120 min. The samples were filtered through a 0.45 μm filter membrane. After mixing, the concentration of SMX was immediately tested using high performance liquid chromatography (HPLC). In addition, the leaching concentrations of Fe and Cu in the material were determined by ICP-S after sample dilution.

[0071] Participate specifically Figure 4 a, b, and c in the example.

[0072] Degradation experiments at different initial pH: The concentration of SMX was set at 50 mg / L, and the concentration of copper-iron sulfide bimetallic material was set at 1.0 g / L. The initial pH was then adjusted to 3.0–11.0 using 0.1 M H₂SO₄ and 0.1 M NaOH. The conical flasks were placed on a magnetic stirrer for reaction under air atmosphere. Samples of 2 mL were taken at intervals of 0–120 min. The samples were filtered through a 0.45 μm filter membrane. Immediately after mixing, the concentration of SMX was measured using high-performance liquid chromatography (HPLC). Additionally, the leaching concentrations of Fe and Cu in the material were measured using ICP-S after sample dilution. For details, please refer to [the relevant documentation / reference needed]. Figure 4 d, e, and f in the example.

[0073] Therefore, according to Figure 4The results demonstrate that the minimum dosage of the copper-iron sulfide bimetallic catalyst prepared by this invention is 0.1 g / L, and it degrades SMX at pH 3.0–11.0. After the reaction, except at pH 3.0, the leaching concentration of Cu is below 1 mg / L, and that of Fe is less than 1 mg / L, both meeting the Class III discharge standard of the Integrated Wastewater Discharge Standard GB 8978-1996. Therefore, the mechanism of SMX degradation by this method may be as follows: Fe 2+ Alternatively, Cu(I) activates oxygen to generate superoxide radicals, which further produce singlet oxygen and then degrade organic pollutants.

[0074] FeCu-S material activates oxygen at pH values ​​between 3 and 11, but the degradation rate of SMX decreases with increasing pH. Under acidic conditions, the leaching of Fe and Cu is higher than at other pH values, and at pH 3, the leaching concentrations of Fe and Cu are 0 and 70 mg / L, respectively. Under other pH conditions, the leaching of Fe and Cu meets the relevant standards. The degradation rate of SMX increases with increasing material dosage; 0.1 g / L of material degrades 50 mg / L of SMX within 120 min, but the leaching of Fe and Cu does not increase with increasing material dosage.

[0075] Example 3

[0076] like Figure 1 The operation flowchart is shown: using CuCl2 and Fe 0 Different proportions of copper-iron sulfide bimetallic catalysts were prepared with Na2S, as shown in Table 2.

[0077] Table 2. Effect of different S / Fe molar ratios on the catalytic performance of copper sulfide iron bimetallic catalytic materials.

[0078]

[0079] In the operation, first prepare an acetic acid-sodium acetate solution by dissolving 56g of sodium acetate in 1L of ultrapure water. Then, adjust the pH of the solution to 6.2 with acetic acid, and aerate the solution with nitrogen for 30 minutes to remove oxygen. Next, add copper chloride and reduced iron powder according to an nS / Fe ratio of 0–0.46. After the reagents are thoroughly mixed and dissolved, add sodium sulfide, and then stir with a magnetic stirrer at room temperature for 12 hours at a stirring speed of 300 rpm. After the reaction, let the mixture stand for 30 minutes to allow the precipitate to settle. Pour off the supernatant, retaining only the precipitate. Then, perform a second separation using vacuum filtration, and wash three times each with ultrapure water and anhydrous ethanol. Place the washed solid in a freeze dryer and dry for 12 hours, then place it in a vacuum bag and store it under vacuum for later use.

[0080] A 250 mg / L SMX stock solution was prepared using SMX, and the SMX concentration was set to 50 mg / L in an Erlenmeyer flask. The initial pH was then adjusted to 7 using 0.1 M H₂SO₄ and 0.1 M NaOH. The concentration of the copper-iron sulfide bimetallic material in Table 2 was set to 1.0 g / L. The Erlenmeyer flask was placed on a magnetic stirrer for reaction under air atmosphere. 1 mL samples were taken at intervals between 0 and 120 min. The samples were filtered through a 0.45 μm filter membrane, and the SMX concentration was immediately measured using high-performance liquid chromatography (HPLC) after thorough mixing.

[0081] The removal rate is calculated according to (Equation 1), corresponding to Figure 5 a and Figure 5 As shown in b, the degradation efficiency and rate of SMX were highest when S / Fe = 0.05. Furthermore, the Cu ion leaching concentration in the system after the reaction was less than 1 mg / L, meeting relevant standards.

[0082] Example 4

[0083] like Figure 1 The operation flow chart shows that copper-iron sulfide bimetallic catalysts with different proportions of CuCl2, FeO, and Na2S were prepared. The specific proportions are shown in Table 3.

[0084] Table 3. Effects of different Cu / Fe molar ratios on the catalytic performance of copper sulfide-iron bimetallic catalytic materials.

[0085]

[0086] In the operation, first prepare an acetic acid-sodium acetate solution by dissolving 56g of sodium acetate in 1L of ultrapure water. Then, adjust the pH of the solution to 6.2 with acetic acid, and aerate the solution with nitrogen for 30 minutes to remove oxygen. Next, add copper chloride and reduced iron powder according to nCu / Fe = 0–1.30. After the reagents are mixed and dissolved, add sodium sulfide, and then stir with a magnetic stirrer at room temperature for 12 hours at a speed of 300 rpm. After the reaction, let the mixture stand for 30 minutes to allow the precipitate to settle. Pour off the supernatant, retaining only the precipitate. Then, perform a second separation using vacuum filtration, and wash three times each with ultrapure water and anhydrous ethanol. Place the washed solid in a freeze dryer to dry for 12 hours, and then store it in a vacuum bag under vacuum for later use.

[0087] A 250 mg / L SMX stock solution was prepared using SMX, and the SMX concentration was set to 50 mg / L in an Erlenmeyer flask. The initial pH was then adjusted to 7 using 0.1 M H₂SO₄ and 0.1 M NaOH. The concentration of the copper-iron sulfide bimetallic material in Table 3 was set to 1.0 g / L. The Erlenmeyer flask was placed on a magnetic stirrer for the reaction under air atmosphere. 1 mL samples were taken at intervals between 0 and 120 min. The samples were filtered through a 0.45 μm filter membrane, and the SMX concentration was immediately measured using high-performance liquid chromatography (HPLC) after thorough mixing.

[0088] The removal rate is calculated according to (Equation 1), through Figure 5 c and Figure 5 As shown in d, the higher the Cu / Fe ratio, the faster the degradation rate of SMX and the larger the reaction rate constant, but the higher the Cu ion concentration in the solution.

[0089] Example 5

[0090] like Figure 1 The operation flowchart is shown below: 100 mL of ultrafiltration effluent from landfill leachate in a city in Hubei Province was placed in a 250 mL Erlenmeyer flask. The properties of the landfill leachate are shown in Table 4. The concentrations of copper-iron sulfide bimetallic material were set at 3 g / L, 5 g / L, and 10 g / L. Under air atmosphere, the Erlenmeyer flask was placed on a magnetic stirrer for reaction. After 10 hours of reaction, samples were taken. The samples were filtered through a 0.45 μm filter membrane, and immediately after mixing, they were added to a COD digestion tube for digestion and absorbance measurement (λ = 540 nm). Another 5 mL of sample was diluted and its TOC and three-dimensional fluorescence were measured.

[0091] Table 4. Various indicators of ultrafiltration effluent from landfill leachate in a city in Hubei Province

[0092]

[0093] Given the complex composition of landfill leachate, the following analysis will focus on the two indicators of COD and TOC.

[0094] The removal rate is calculated according to (Equation 1), such as Figure 6 As shown in Figure a, the COD removal efficiency in landfill leachate increased to 15.04%, 37.32%, and 35.97% with increasing FeCu-S dosage, reaching saturation when the dosage exceeded 5 g / L. TOC removal efficiency increased with increasing dosage, and the wastewater color decreased significantly after the reaction. EEM analysis revealed varying degrees of reduction in the concentrations of humic acid-like substances, fulvic acid-like substances, tryptophan-like substances, tyrosine-like substances, and aromatic protein-like organic matter after treatment.

[0095] The treated wastewater achieved a COD removal efficiency of over 37%, with a COD concentration of 199 mg / L. The TOC removal rate was 32%, with a TOC concentration of 80.1 mg / L. The decolorization effect was significant, with a color index of 11, indicating that this method can effectively remove COD while simultaneously reducing wastewater color. The COD level is lower than the 200 mg / L requirement of the Class II standard in the "Integrated Wastewater Discharge Standard" (GB8978-1996), and far below the 50 mg / L requirement of the Class I standard. Therefore, the treated wastewater can be directly discharged or further utilized for resource recovery.

[0096] like Figure 6 As shown in c, the three-dimensional fluorescence results show that after copper-iron sulfide bimetallic treatment, the concentration of humic acid-like substances in landfill leachate decreased by 7-8 levels, tryptophan-like substances decreased by 5 levels, aromatic proteins decreased by 6 levels, and various fluorescence characteristic peaks were significantly reduced.

[0097] Example 6

[0098] like Figure 1 The operation flowchart is shown below: 100 mL of biochemical effluent from landfill leachate in a city in Hubei Province was placed in a 250 mL Erlenmeyer flask. The properties of the landfill leachate are shown in Table 5. The concentrations of copper-iron sulfide bimetallic material were set at 3 g / L, 5 g / L, and 10 g / L. Under air atmosphere, the Erlenmeyer flask was placed on a magnetic stirrer for reaction. After 10 hours of reaction, samples were taken. The samples were filtered through a 0.45 μm filter membrane, and immediately after mixing, they were added to a COD digestion tube for digestion and absorbance measurement (λ = 540 nm). Another 5 mL of sample was diluted and its TOC and three-dimensional fluorescence were measured.

[0099] Table 5. Various indicators of biochemical effluent from landfill leachate in a city in Hubei Province

[0100]

[0101] Given the complex composition of landfill leachate, the following analysis will focus on two key indicators: COD and TOC.

[0102] The removal rate is calculated according to (Equation 1), such as Figure 7 As shown in Figure a, with the increase of FeCu-S dosage, the COD removal efficiency in landfill leachate was 14.09%, 41.03%, and 55.73%, respectively. The TOC removal efficiency increased with the increase of dosage, and the color of the wastewater decreased after the reaction. EEM analysis showed that the concentrations of humic acid-like substances, fulvic acid-like substances, tryptophan-like substances, tyrosine-like substances, and aromatic protein-like substances all decreased to varying degrees after treatment, especially humic acid-like substances, fulvic acid-like substances, tryptophan-like substances, and tyrosine-like substances.

[0103] After treatment, the COD removal efficiency reached 56%, and the COD concentration in the treated wastewater was 102.7 mg / L. The TOC removal rate was 34.8%, and the TOC concentration in the wastewater after the reaction was 67.8 mg / L. The decolorization effect was significant, with a color index of 6, indicating that the method used in this study can effectively remove COD while also reducing the color of the wastewater. The COD index is lower than the "Integrated Wastewater Discharge Standard".

[0104] The standard requirement of no more than 200 mg / L in the secondary standard of (GB8978-1996) is far lower than the standard requirement of no more than 50 mg / L in the primary standard of "Integrated Wastewater Discharge Standard" (GB8978-1996). The treated wastewater can be directly discharged or further utilized for resource recovery.

[0105] Combining Examples 5 and 6, the mechanism by which the catalyst prepared by this invention degrades COD was verified to be: organic matter is first adsorbed onto the surface of the conductive material by zero-valent Cu, and then by Fe... 2+ Cu(I) activates oxygen to generate superoxide radicals, which are then further synthesized into hydrogen peroxide to generate hydroxyl radicals. Hydroxyl radicals have strong oxidizing properties and can react with organic matter to oxidize it until it is mineralized to generate CO2, thereby reducing the TOC concentration in the system.

[0106] like Figure 7 As shown in Figures c and d, the three-dimensional fluorescence results show that after treatment with copper-iron sulfide bimetallic solution, the concentration of humic acid-like substances in the landfill leachate decreased by 8 levels, tryptophan-like substances decreased by 5 levels, aromatic proteins decreased by 8 levels, and various fluorescence characteristic peaks were significantly reduced.

[0107] Example 7

[0108] like Figure 1 The operation flow chart is shown below: Take an appropriate amount of copper-iron sulfide bimetallic catalyst and quartz sand, with a mass ratio of quartz sand to FeCu-S of 17g:2g, and fill it into a continuous flow device with a height of 6cm and an inner diameter of 1cm. Figure 8 The pump flow rate was set to 0.05 mL / min, the hydraulic retention time to 2 hours, and the volume per pore (PV) to 6 mL. After 12 hours of continuous treatment, the catalyst was replaced, and the process was repeated for 36 hours to investigate the removal effect of SMX and the stability of the material.

[0109] The treated wastewater showed a SMX degradation efficiency of over 85%, indicating that the bimetallic sulfide catalyst prepared by the method of this invention has good performance and stable operation for 36 hours.

[0110] This invention can effectively degrade sulfamethoxazole (SMX, 10-150 mg / L), landfill leachate ultrafiltration effluent, and landfill leachate biochemical effluent (designated Raw and Raw2, with initial COD concentrations of 200-400 mg / L, respectively). The degradation efficiency for both SMX and dyes can reach over 99%. For Raw wastewater with a COD concentration of 318 mg / L, the highest COD removal efficiency can reach 37% (removing approximately 118.6 mg / L), and the TOC removal efficiency is 32% (removing 37.3 mg / L), with a significant reduction in color. For Raw2 wastewater with a COD concentration of 232 mg / L, the highest COD removal efficiency can reach 55% (removing approximately 129.3 mg / L), and the TOC removal efficiency is 35% (removing 36.2 mg / L), with a significant reduction in color.

[0111] Example 8

[0112] like Figure 1 The operation flowchart shows: further determine the adsorption and degradation effect of copper-iron sulfide bimetallic catalyst on SMX, test the catalyst's TOC removal efficiency, desorption experiment, nitrogen atmosphere experiment, and the main active species for SMX degradation.

[0113] TOC experiment: The concentration of copper sulfide iron bimetallic material was set at 1 g / L and the concentration of SMX was 50 mg / L. After reacting for 2 hours, the solid and liquid were separated, and the TOC concentration of the liquid and solid samples was measured.

[0114] Desorption experiment: The concentration of copper-iron sulfide bimetallic material was set at 1 g / L and the concentration of SMX was 50 mg / L. After reacting for 2 h, solid-liquid separation was performed. The solid material was added to an ethanol solution and reacted for 2 h. Then, a sample was taken to measure the concentration of SMX.

[0115] Nitrogen atmosphere experiment: Place a 50 mg / L SMX solution in an anaerobic double-pass bottle and aerate with nitrogen for more than 30 minutes to remove oxygen from the solution. Then add 1 g / L FeCu-S or control group 2. Aerate with nitrogen continuously during the reaction process, and then take samples at regular intervals to measure the concentration of SMX in the solution.

[0116] EPR test: 1 g / L FeCu-S was added to a 50 mg / L SMX solution. Then, 1 mL of the sample was filtered through a 0.22 μm filter membrane. 5,5-Dimethyl-1-pyrrolidone-N-oxide (DMPO) was added to capture hydroxyl radicals, and the radical signal was measured using electron paramagnetic resonance (EPR) spectroscopy. Another 1 mL of the sample was added to 2,2,6,6-tetramethylpiperidine N-oxide (TMPO) to capture singlet oxygen, and the result was also measured using EPR.

[0117] Quenching experiment: Six beakers containing 50 mg / L SMX solution were prepared. The beakers were configured with 500 mg / L cationic superoxide dismutase (CAT), 1 mol / L methanol (MeOH), 1 mol / L tert-butanol (TBA), 1 mol / L furfuryl alcohol (FFA), 10 μmol / L p-benzoquinone (BQ), and a control group without additives. Then, 1 g / L FeCu-S was added to each beaker, and the SMX concentration was measured periodically.

[0118] Figure 9 The solid surface (e.g., after 120 min of reaction between the copper-iron bimetallic catalyst and the control group) Figure 9 a) of species and in liquids (such as Figure 9 b) TOC concentration and SMX desorption ratio (e.g.) Figure 9 c), the degradation efficiency of SMX under nitrogen atmosphere (e.g. Figure 9 d) and EPR (Electron Paramagnetic Resonance) maps (such as Figure 9 The results showed that the TOC removal efficiency of the FeCu-S group was close to 100% after 2 hours of reaction. The solid TOC contents of FeCu-S, Cu-S, Fe-S, and Fe-Cu were 21.33 g / kg, 16.13 g / kg, 1.62 g / kg, and 10.45 g / kg, respectively, proving that FeCu-S does indeed have an adsorption effect on organic matter. The desorption results also showed that FeCu-S desorbed only 15% of the original SMX. The SMX degradation efficiency decreased significantly under a nitrogen atmosphere (oxygen shielding), indicating that FeCu-S material has a degradation and adsorption effect on SMX. However, it cannot be ruled out that the catalyst can activate the adsorbed oxygen and lattice oxygen on the material surface. Therefore, it is judged that the degradation of SMX by FeCu-S is the main removal effect. EPR results showed that methyl radicals, hydroxyl radicals, and singlet oxygen were present in the system. Quenching results showed that singlet oxygen was the main active species for SMX degradation.

[0119] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter, characterized in that, The method includes: Under anaerobic conditions, copper chloride and iron powder are added to an acidic buffer solution, mixed evenly, and then sodium sulfide solution is added. After stirring at room temperature for a one-step reaction, the mixture is filtered to obtain the copper-iron sulfide bimetallic catalyst. The molar ratio of copper chloride to iron powder is in the range of 0.3 to 1.3, and the molar ratio of sodium sulfide to iron powder is in the range of 0.046 to 0.

46. The copper-iron sulfide bimetallic catalyst contains CuFeS2, CuO, FeO, and Cu.

2. The method for preparing the copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter according to claim 1, characterized in that, The acidic buffer solution is one of acetic acid-sodium acetate solution, citric acid-sodium citrate solution, and formic acid-sodium formate solution, and is used after being deoxygenated.

3. The method for preparing the copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter according to claim 2, characterized in that, The acidic buffer solution is an acetic acid-sodium acetate solution, and the mass-to-volume ratio of sodium acetate to acetic acid is 45-50 g / mL.

4. The method for preparing the copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter according to claim 1, characterized in that, The pH of the acidic buffer solution is 5.6 to 7.

5. The method for preparing the copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter according to claim 4, characterized in that, The pH of the acidic buffer solution is 6.0 to 6.

4.

6. The method for preparing the copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter according to claim 1, characterized in that, The reaction time is 8 to 15 hours.

7. The method for preparing the copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter according to claim 1, characterized in that, The purity of copper chloride and iron powder is greater than or equal to 99%.

8. The copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter, prepared by the method of any one of claims 1-7, is characterized in that... The copper-iron sulfide bimetallic catalyst comprises CuFeS2, CuO, FeO, and Cu.

9. The application of the copper-iron sulfide bimetallic catalyst for activating oxygen to degrade organic matter as described in claim 8 in the treatment of organic wastewater.

10. The application according to claim 9, characterized in that, Organic wastewater is wastewater containing aromatic compounds.

11. The application according to claim 9, characterized in that, The application includes the following steps: (1) Prepare the organic wastewater to be treated; (2) Weigh the copper-iron sulfide bimetallic catalyst and add it to the organic wastewater in step (1), and stir it in an air atmosphere; wherein the dosage of the copper-iron sulfide bimetallic catalyst is 1 ~ 10 g / L. (3) After treatment, filter and recycle the sediment in the wastewater system for reuse.

12. The application according to claim 9, characterized in that, The application includes filling the copper-iron sulfide bimetallic catalyst into a column reactor, and pumping the organic wastewater to be treated from the bottom of the column after full aeration for treatment.

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