Iron oxide-molybdenum disulfide heterojunction catalyst and preparation method and application thereof

Abstract

The application relates to the field of environmental engineering and discloses an iron oxide-molybdenum disulfide heterojunction catalyst as well as a preparation method and application thereof. Sodium molybdate dihydrate and cysteine are dissolved in water, ultrasonic dispersion is carried out, ball milling treatment is carried out, a sulfur-containing molybdenum-based precursor is obtained through a first hydrothermal reaction, iron salt is added to carry out a second hydrothermal reaction, and the catalyst is obtained through washing and drying. The catalyst is easy to disperse in water, has a large specific surface area, is high in iron element content and uniform in iron element distribution, can form a large number of Fe-S-Mo synergistic active centers, can efficiently activate persulfate in a pH range of 2-10, and can remove chlorobenzoic acid by about 100% in 5 minutes under the condition of an initial concentration of 10 mg / L and near-neutral pH. The catalyst has rapid and efficient degradation performance on antibiotic organic pollutants, the preparation process does not need toxic and harmful organic solvents, the catalyst has stable structure and is environment-friendly, and is suitable for engineering scale-up application.

Description

Technical Field

[0001] This invention relates to the field of environmental engineering, and more specifically, to an iron oxide-molybdenum disulfide heterojunction catalyst, its preparation method, and its application. Background Technology

[0002] Antibiotics are widely recognized as typical emerging organic pollutants. After clinical and aquaculture use, they are excreted into wastewater systems and will continue to accumulate in the aquatic environment if not effectively removed during wastewater treatment. These pollutants are mostly structurally stable organic molecules, exhibiting recalcitrant behavior, potential ecotoxicity, and bioaccumulation, placing higher demands on traditional physical, chemical, and biological treatment processes. To achieve deep removal of these recalcitrant organic pollutants, advanced oxidation technologies that generate highly reactive species such as hydroxyl radicals, sulfate radicals, and singlet oxygen have received widespread attention in recent years. Among these, persulfate-activated advanced oxidation technologies have become a research hotspot due to their strong oxidizing power and wide applicable pH range. The key to this technology lies in constructing efficient, economical, and environmentally friendly activation methods and catalytic materials to improve the removal efficiency of pollutants such as antibiotics.

[0003] However, existing sulfur-containing molybdenum-based iron-based catalytic materials for activating persulfate still have certain limitations. While patent CN120479457A proposes a catalytic system with iron atoms supporting molybdenum disulfide, its preparation process focuses on obtaining specific crystal phases and flower-shaped morphologies of MoS2. It involves multiple steps in a system containing various reducing agents and promoters to introduce iron active centers, resulting in a large variety of raw materials, complex reaction steps, and high sensitivity to crystal phase control and reduction conditions, which is not conducive to industrial production. Patent CN114100638A improves catalytic performance to some extent by simultaneously introducing iron and carbon into the interlayer of MoS2 to form an intercalation structure, but it requires additional organic reducing agents and carbon sources, making the system composition and reaction process more complex. It is highly dependent on the formation and maintenance conditions of the intercalation structure, and the stability and repeatability of the interlayer structure cannot be guaranteed under complex water conditions and multiple cycles of use. Patent CN118403644A uses FeOF particles as the main active component and loads them on the surface of MoS2 nanosheets to construct a composite catalytic system. This type of catalyst has a multiphase interface and multi-component synergy. During the preparation process, the particle size, loading ratio and binding mode of FeOF with MoS2 need to be finely adjusted. The overall structure of the system is relatively complex. Under different pH conditions and in the presence of coexisting ions, the stability of the interface structure and active components is uncertain.

[0004] In summary, among the existing technologies mentioned above, traditional modification processes for other materials often involve numerous steps, complex factors, and narrow reaction window conditions. Some modified materials exhibit weak structural adaptability in actual aquatic environments, with instances of structural instability or loss of active components. This increases raw material and operating costs, and the catalytic effect is prone to decay during use, making it difficult to maintain treatment efficiency over the long term. Therefore, simplifying the modification process of sulfur- and molybdenum-based materials, improving their structural stability, and enhancing their adaptability to complex aquatic conditions while maintaining high catalytic activity remain pressing technical challenges in this field. Summary of the Invention

[0005] To overcome the shortcomings of existing persulfate-activated iron-based persulfate-activated persulfate catalysts, such as complex preparation process, insufficient structural stability, and limited removal efficiency of pharmaceutical organic pollutants under wide pH conditions, this invention provides an iron oxide-molybdenum disulfide heterojunction catalyst. Another object of the present invention is to provide a method for preparing an iron oxide-molybdenum disulfide heterojunction catalyst; Another object of the present invention is to provide an application of an iron oxide-molybdenum disulfide heterojunction catalyst; Another object of the present invention is to provide a method for degrading antibiotic-like organic pollutants in water.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for preparing an iron oxide-molybdenum disulfide heterojunction catalyst includes the following steps: S1. Dissolve and disperse molybdate and sulfur-containing compounds; S2. The resulting mixed solution is ball-milled. S3. Perform the first hydrothermal reaction on the ball-milled mixture; S4. A second hydrothermal process is performed in the presence of iron salts to obtain the iron oxide-molybdenum disulfide heterojunction catalyst. The iron salt is added to the system at least in one of the stages before the first hydrothermal reaction and before the second hydrothermal reaction.

[0007] Preferably, the molybdate includes sodium molybdate and ammonium molybdate.

[0008] Preferably, the sulfur-containing compound includes cysteine, thiourea, cysteamine, and glutathione.

[0009] Preferably, the molybdate is sodium molybdate, and the sulfur-containing compound is cysteine.

[0010] Preferably, the iron salt is added after S3 is completed, or it is added in S1 together with the molybdate and the sulfur-containing compound.

[0011] Preferably, the iron salt is added after step S3 is completed.

[0012] Preferably, the iron salt includes ferrous sulfate, polyferric sulfate, and ferric acetylacetone.

[0013] Preferably, the iron oxide-molybdenum disulfide heterojunction catalyst (Fe x O y The mass percentages of each element in @MoS2 are approximately O (20%-35%), S (15%-25%), Mo (5%-15%), and Fe (25%-55%).

[0014] Furthermore, the molar ratio of molybdenum in the molybdate to sulfur in the sulfur-containing compound is 1:4~8.

[0015] Preferably, ultrasonic stirring and dispersion are performed in S1 for 3-5 minutes.

[0016] Preferably, the grinding balls used in the S2 ball milling process are selected from one or more types with a particle size of 6 to 10 mm, and the number is at least 8.

[0017] Preferably, the grinding balls used in the S2 ball milling process are agate grinding balls, and the grinding balls are configured as follows: 4 balls with a diameter of 10 mm and 6 balls with a diameter of 6 mm.

[0018] Furthermore, during the S2 ball milling process, the rotation speed is 400~700 r / min, and the milling time is 60~120 min.

[0019] Preferably, during the S2 ball milling process, the rotation speed is 500~600 r / min and the ball milling time is 60~120 min.

[0020] Preferably, during the S2 ball milling process, the rotation speed is 500 r / min and the milling time is 60 min.

[0021] Furthermore, the temperature of the first and second hydrothermal reactions is 160~220℃, and the hydrothermal time is 12~36 h.

[0022] Preferably, the temperature of the first hydrothermal reaction and the second hydrothermal reaction are 200°C, and the hydrothermal time is 24 h.

[0023] Preferably, the temperature and time of the first hydrothermal reaction and the second hydrothermal reaction are kept consistent.

[0024] Preferably, the temperature is increased to 200°C at a rate of 10°C / min.

[0025] Furthermore, after adding iron salt to S4, the mass ratio of molybdenum to iron in the system is 1~10:1.

[0026] Preferably, after adding iron salt to S4, the mass ratio of molybdenum to iron in the system is 1~3:1 or 5~10:1.

[0027] Preferably, the product of the second hydrothermal reaction is washed multiple times in alcohol and water and then dried. Preferably, the alcohol includes at least one of ethanol and glycerol; Preferably, the alcohol, water, and alcohol are added to the centrifuge tube in the following order for washing; Preferably, the washing process is carried out by centrifugation, with the centrifugation rate controlled at 4000 r and the duration at 5 min. Preferably, the washed product is transferred with anhydrous ethanol and then dried at 80°C.

[0028] An iron oxide-molybdenum disulfide heterojunction catalyst is prepared by the same method used for preparing the iron oxide-molybdenum disulfide heterojunction catalyst.

[0029] An application of the aforementioned iron oxide-molybdenum disulfide heterojunction catalyst for the activation of persulfate.

[0030] Furthermore, antibiotic-like organic pollutants in water are degraded by activating oxidants.

[0031] Preferably, the oxidant includes persulfate and hydrogen peroxide; Preferably, the oxidant is persulfate; Preferably, the sulfate includes potassium persulfate and potassium perdisulfate.

[0032] Preferably, the antibiotic-like organic pollutant includes clofibrate and its derivatives. A method for degrading antibiotic-like organic pollutants in water uses the iron-modified molybdenum-based catalyst.

[0033] Furthermore, the dosage of the iron oxide-molybdenum disulfide heterojunction catalyst in water is 0.1~0.3 g / L.

[0034] Furthermore, the pH of the reaction system for degrading antibiotic-like organic pollutants in the water is 2-10.

[0035] Preferably, the pH of the reaction system for degrading antibiotic-like organic pollutants in water is 2-6.

[0036] Preferably, the water contains an oxidant.

[0037] Preferably, the mass ratio of the iron oxide-molybdenum disulfide heterojunction catalyst to the oxidant is 1:1~3.

[0038] This invention creatively proposes a holistic approach that uses a sulfur-containing molybdenum-based porous layered material as a template framework, and achieves the formation of a heterogeneous structure with iron oxides through ball milling pretreatment combined with a hydrothermal process, rather than simply following the existing approach of loading iron particles, intercalating iron-carbon, or composite FeOF on the MoS2 surface. This invention selects a sulfur-containing molybdenum-based porous material as the main framework, utilizes ball milling to enhance the mixing and contact between the molybdenum source, sulfur-containing organic ligands, and iron salts, and then, through a single or staged hydrothermal reaction, embeds and couples iron oxides into and onto the interior and surface of the layered structure, forming a lightweight, high specific surface area, easily dispersed in water, and iron ions firmly confined within the support catalytic material.

[0039] Unlike existing modification routes that heavily rely on complex organic ligands, strong reducing agents, or multi-step crystal phase regulation, this invention achieves the goal of constructing high-density Fe-S-Mo synergistic active centers under mild conditions in aqueous or water-alcohol phase systems by combining specific process sequences and treatment methods, while maintaining the quality and structural stability of the finished product.

[0040] This invention combines the aforementioned catalyst with an oxidant activation system such as persulfate, exhibiting excellent degradation performance on antibiotic-like organic pollutants such as clofibrate without the use of toxic or harmful organic solvents. This invention simplifies the modification process, improves catalyst structural stability and aquatic adaptability, while still achieving highly efficient degradation of the aforementioned recalcitrant pharmaceutical-like organic pollutants.

[0041] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: The catalyst described in this invention can be uniformly dispersed in water, exhibiting a layered porous structure with a large specific surface area, allowing it to fully contact persulfate and pollutants in the water, thereby improving reaction efficiency.

[0042] The catalyst obtained by this invention contains iron, oxygen, sulfur, and molybdenum at mass fractions of 43.54%, 32.51%, 17.05%, and 6.90%, respectively. The iron content is high and uniformly distributed, which can form a large number of Fe-S-Mo synergistic active centers. Under the same conditions, sulfur-containing molybdenum-based materials without iron can only remove about 10% of pollutants in 60 minutes, while the catalyst of this invention can achieve a removal rate of nearly 100% in about 5 minutes.

[0043] The catalyst of this invention can activate persulfate in the pH range of 2 to 10, effectively degrade pharmaceutical organic pollutants such as clofibrate, and achieve a high removal rate within minutes under near-neutral conditions, taking into account both the treatment effect and the adaptability to actual water environment conditions. Attached Figure Description

[0044] Figure 1 Fe obtained from the example xO y The characterization results of @MoS2, a~c represent Fe at different magnifications. x O y @MoS2 surface SEM image, d is the EDS selected area and element distribution map; Figure 2 Fe obtained with different molybdenum-iron ratios x O y @MoS2 degradation rate; Figure 3 Fe obtained by different preparation methods x O y @MoS2 degradation rate; Figure 4 Fe obtained under different ball milling conditions x O y @MoS2 degradation rate; Figure 5 Degradation rate at different pH values; Figure 6 Fe obtained from different iron salts x O y The degradation rate of @MoS2 with different oxidants: a) ferric salt is polyferric sulfate, b) ferrous salt is ferrous sulfate, and c) ferric salt is acetylacetonate iron. Figure 7 For different Fe x O y @Degradation rate of MoS2 input 。 Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0046] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0047] Example 1 1. Preparation of iron oxide-molybdenum disulfide heterojunction catalysts The synthetic raw materials were prepared in proportion using an aqueous solution as the medium. First, 0.8 g of cysteine ​​and 0.25 g of sodium molybdate (molybdenum-sulfur ratio 1:5) were accurately weighed using an analytical balance, and then 60 mL of water was added. After preparation, the mixture was sonicated for 3-5 minutes to obtain a dispersion. The dispersion was transferred to a ball mill jar, and four 10 mm agate grinding beads and six 6 mm agate grinding beads were added. The jar was placed in a ball mill and the milling machine was set to 500 rpm for 1 hour. The milled product was then transferred to a 100 mL pressure vessel and kept in an oven or muffle furnace at 200°C for 24 hours. Then, 0.25 g of ferrous sulfate heptahydrate was added to the hydrothermal jar, and the mixture was kept in an oven or muffle furnace at 200°C for another 24 hours to synthesize the black reactant. The black reactant was centrifuged and then washed alternately with alcohol solution, aqueous solution, and alcohol solution, with the centrifugation rate controlled at 4000 r for 5 min throughout the washing process. The washed product was then transferred from the centrifuge tube to an evaporating dish using an alcohol solution. The evaporating dish was placed in an oven and dried at 80°C. This yielded the Fe oxide-molybdenum disulfide heterojunction catalyst material. x O y @MoS2.

[0048] 2. Iron oxide-molybdenum disulfide heterojunction catalyst activates persulfate degradation of clofibrate. Add 100 mL of clofibrate solution with a concentration of 10 mg / L to an Erlenmeyer flask, then add 0.01 g of iron oxide-molybdenum disulfide heterojunction catalyst (adjust pH to 6), and quickly add 2 mL of persulfate (PMS) solution with a concentration of 10 g / L to the Erlenmeyer flask to make the amount of PMS added in the reaction system 0.2 g / L. Stir the reaction at 400 r / min.

[0049] Examples 2-5 The technical solutions of Examples 2 to 5 are similar to those of Example 1, except that the amount of ferrous sulfate heptahydrate added makes the mass ratio of molybdenum to iron 2:1, 4:1, 5:1, and 10:1.

[0050] Examples 6-8 The technical solutions of Examples 6-8 are similar to those of Example 1, except that the added L-cysteine ​​is 0.96, 0.605, and 0.484 g, respectively, which means that the molybdenum-sulfur ratios are 1:4, 1:6, and 1:8.

[0051] Examples 9-10 The technical solutions of Examples 9 and 10 are similar to those of Example 1, except that the ball milling speeds are 500 and 600 r / min, respectively, and the ball milling time is 2 h.

[0052] Example 11 The synthetic raw materials were prepared in proportion using an aqueous solution as the medium. First, 0.8 g of cysteine, 0.25 g of sodium molybdate, and 0.25 g of ferrous sulfate heptahydrate were accurately weighed using an analytical balance, and then 60 mL of water was added. After preparation, the mixture was sonicated for 3-5 minutes to obtain a dispersion. The dispersion was transferred to a ball mill jar, and four 10 mm agate grinding beads and six 6 mm agate grinding beads were added. The jar was placed in a ball mill and the milling machine was set to 500 rpm for 1 hour. The milled product was then transferred to a 100 mL pressure vessel and incubated at 200°C for 24 hours in an oven or muffle furnace. This process was repeated to obtain a black reactant. The black reactant was centrifuged and then washed with alternating centrifugation solutions of alcohol, aqueous solution, and alcohol solution, with the centrifugation rate controlled at 4000 rpm for 5 minutes throughout the washing process. The washed product was then transferred from the centrifuge tube to an evaporating dish using an alcohol solution. The evaporating dish was then placed in an oven and dried at 80°C. This yielded an iron oxide-molybdenum disulfide heterojunction catalyst material.

[0053] Examples 12-15 The technical solutions of Examples 12-15 are similar to those of Example 1, except that the pH of the system is adjusted to 2, 4, 8 and 10 respectively before adding PMS when degrading chlorpyrifos.

[0054] Examples 16-18 Weigh out 0.8 g of L-cysteine ​​and 0.25 g of sodium molybdate dihydrate (three groups in total). Dissolve the sodium molybdate dihydrate and L-cysteine ​​in a beaker containing 60 ml of N,N-dimethylformamide, transfer to a ball mill jar, and add 6 agate beads with a diameter of 10 mm and 4 agate beads with a diameter of 6 mm. Cover the ball mill jar, check that the seal is intact, and place it in a planetary ball mill. Set the ball mill speed to 400 rpm, and after confirming stability, start the ball mill and run it for one hour. After the ball milling is completed, use a pipette to remove the solid-liquid mixture and transfer it to a polytetrafluoroethylene (PTFE) reactor liner. Transfer the reactor to an oven and heat at 200°C for 24 hours. After the reaction is complete, transfer the reactor to a fume hood to cool. Weigh out iron salts, and after cooling, add the three iron compounds to the three reactors respectively, and continue to react in the 200°C oven for 24 hours. After the reaction is complete, transfer the reactor to a fume hood and cool to room temperature. Pour the liquid from the reactor into two 50 ml centrifuge tubes, and rinse the inner wall of the reactor thoroughly with anhydrous ethanol to wash the product into the centrifuge tubes. Place the 50 ml centrifuge tubes in a centrifuge and centrifuge at 4000 rpm for 5 minutes. Wash three times in the order of anhydrous ethanol, deionized water, and then anhydrous ethanol to remove any unreacted fat-soluble and water-soluble substances. Take the product after the last anhydrous ethanol wash, rinse all solids with anhydrous ethanol into an evaporating dish, and dry in a 70°C oven. After all the liquid has evaporated, collect the catalyst product using a stainless steel scraper.

[0055] The iron salts in Examples 16-18 are 0.139 g of ferrous sulfate heptahydrate, 0.178 g of ferric acetylacetone, and 0.134 g of polyferric sulfate, respectively.

[0056] 2. Iron oxide-molybdenum disulfide heterojunction catalyst activates persulfate to degrade methylene blue solution Prepare oxidants with a concentration of 0.01 g / mL: hydrogen peroxide, potassium persulfate, and potassium persulfate. Add 100 mL of 2 mg / L methylene blue solution to each conical flask, add stir bar, add 0.01 g of each iron source catalyst, and then add 1 mL of each oxidant.

[0057] Examples 19-21 The technical solutions of Examples 19-21 are similar to those of Example 18, except that the amount of iron oxide-molybdenum disulfide heterojunction catalyst added is 0.01 g, 0.02 g, and 0.03 g, respectively. 100 mL of 2 mg / L methylene blue solution was added to each of the three sets of conical flasks, along with the aforementioned weighed catalyst and stirring pellets. Then, 1 mL of 0.01 g / mL potassium persulfate solution was added to each set.

[0058] Comparative Example 1 The technical solution of Comparative Example 1 is similar to that of Example 2, except that FeSO4 is not added at all during the hydrothermal stage.

[0059] Comparative Example 2 The technical solution of Comparative Example 2 is similar to that of Example 2, except that magnetic stirring at 400 rpm is used instead of ball milling.

[0060] Comparative Examples 3-4 The technical solutions of Comparative Examples 3 and 4 are similar to those of Example 1, except that the ball milling speeds are 300 and 400 r / min, respectively, and the ball milling time is 2 h.

[0061] Detection methods 1. Iron oxide-molybdenum disulfide heterojunction catalyst activates persulfate to degrade clofibrate. At specified sampling points (1 min, 2 min, 3 min, 5 min, 8 min, 13 min, 21 min, 34 min, and 55 min), 1 mL of solution was taken using a disposable sampler, filtered through a 0.22 μm filter membrane, and then added to a 2 mL HPLC vial containing 20 μL of 0.1 mol / L sodium thiosulfate solution. The samples were refrigerated and analyzed by HPLC within one week. To eliminate the dilution effect of PMS addition on the total system volume and the apparent concentration of clofibrate, 2 mL of deionized water was added to the blank control sample. The resulting blank sample was used to calculate the relative degradation rate at each time point.

[0062] This method was used to detect the degradation effect of the obtained iron oxide-molybdenum disulfide heterojunction catalyst on PMS for the degradation of clofibrate. The degradation performance was evaluated by liquid chromatography, using the peak area ratio of the sample to the blank sample.

[0063] 2. Iron oxide-molybdenum disulfide heterojunction catalyst activates persulfate to degrade methylene blue solution Samples were taken at 5 min, 15 min, 30 min, 45 min and 60 min of reaction. A suitable amount of reaction solution was drawn using a disposable syringe sampler and passed through a 0.22 μm aqueous polyethersulfone filter into a cuvette. The cuvette was then placed in a calibrated spectrophotometer for measurement. Each group was measured in triplicate.

[0064] Analysis and Explanation

[0065] The SEM results show that Fe x O y @MoS2 exhibits a uniformly distributed spherical porous structure and can be considered a MoS2-based material at the molecular level and above. From Figure 1 As can be observed at a~c, Fe x Oy @MoS2 particles are smaller in size and pore size than MoS2-based materials. Their compact spherical structure and abundant pores are beneficial to significantly increasing the specific surface area of ​​the catalyst and providing a large number of easily accessible surface and pore-based reactive sites, thereby facilitating the achievement of excellent organic pollutant degradation performance.

[0066] like Figure 1 As shown, energy-dispersive X-ray spectroscopy (EDS) surface scanning results confirm that the mass fractions of iron, oxygen, sulfur, and molybdenum in the composite catalytic material of this invention are 43.54%, 32.51%, 17.05%, and 6.90%, respectively, and the atomic ratio conforms to Fe x O y / MoS2 heterostructure characteristics. The above elemental composition and spatial distribution indicate that, using the "ball milling-segmented hydrothermal" process described in the claims, a high concentration of sulfur vacancies can be generated in situ on the MoS2 surface, and iron oxides can be deposited in a confined manner using these vacancies as anchoring points, thereby constructing a high-loading, highly dispersed Fe... x O y @MoS2 interfacial active center; this structure is beneficial for enhancing the activation efficiency of persulfate and significantly improving the degradation performance of target organic pollutants.

[0067] 2. Degradation effect (1) Degradation of clofibrate Figure 2 The results showed that the catalyst exhibited the best degradation performance for clofibrate when the molybdenum-to-iron (Mo:Fe) ratio was 2:1 (Example 2), achieving nearly 100% degradation within 5 minutes. With decreasing iron dosage, the overall catalytic degradation performance declined: at a Mo:Fe ratio of 4:1 (Example 3), only about 50% of the clofibrate was removed after 21 minutes; when the Mo:Fe ratio was further increased to 5:1 (Example 4), the catalytic degradation effect improved, with a clofibrate removal rate exceeding 90% after 21 minutes; when the Mo:Fe ratio was 10:1 (Example 5), the degradation performance decreased again, but the removal rate still reached approximately 80% after 21 minutes, higher than the catalyst prepared under the 4:1 condition. In summary, the degradation performance of the catalyst exhibits a non-monotonic change with the Mo:Fe ratio, with the best degradation effect observed at a Mo:Fe ratio of 2:1.

[0068] As shown in Table 1, under the same reaction conditions, the molybdenum-sulfur catalysts in Examples 1 and 6-8, with different ratios, all exhibited the ability to degrade clofibrate, but their catalytic efficiencies differed significantly. When the molybdenum-sulfur ratio was 1:5 (Example 1), the catalyst showed the best degradation performance, achieving complete degradation of clofibrate (100% degradation rate) in just 8 minutes. In contrast, the catalyst with a molybdenum-sulfur ratio of 1:4 (Example 6) performed relatively poorly, with a degradation rate of only 83.3% within 5 minutes.

[0069] Table 1 Degradation rates at different molybdenum-sulfur molar ratios

[0070] like Figure 3 As shown, Example 2 can almost completely degrade clofibrate (CA) in about 5 minutes, while in Comparative Example 1, without the addition of ferrous sulfate heptahydrate in the hydrothermal reaction stage, the removal rate of CA by iron-free MoS2 within 60 minutes is only about 10%, indicating that MoS2 with only sulfur vacancies cannot provide sufficient catalytic activity, and the introduction of Fe is the key to forming highly efficient active sites. In the reaction system of Comparative Example 2, no oxidant is added, and the removal of CA is only manifested by adsorption, with a removal rate of only about 1.1% after 34 minutes, indicating that the catalyst of the present invention does not rely on the adsorption pathway to remove CA from water. In addition, in Example 11, iron salt was added before the first hydrothermal reaction, and the resulting catalyst could degrade about 80% of CA in 5 minutes, indicating that the order of iron salt addition has a slight impact on the degradation rate.

[0071] In Comparative Example 2, where magnetic stirring replaced ball milling, the resulting catalyst only degraded about 50% of CA after 5 minutes, significantly lower than in Example 2. Ball milling enhances the mixing and contact of the precursors and facilitates the early synthesis of some molybdenum disulfide and molybdenum trisulfide. This leads to the consumption of precursor materials, creating a competitive sulfur source mechanism between the formation of molybdenum trisulfide and layered molybdenum disulfide within the system, ultimately resulting in a layered molybdenum disulfide and molybdenum trisulfide system rich in surface sulfur defects. Furthermore, by adding ferrous sulfate followed by a second hydrothermal treatment, using a sulfur vacancy confinement and anchoring strategy, iron oxides are introduced into the sulfur vacancies, achieving a high-content and highly dispersed iron oxide heterostructure on the MoS2 matrix, ultimately making the catalyst more active. Further... Figure 4 From the perspective of ball milling time, the degradation rate was low at 300 r / min (Comparative Example 3) and 400 r / min (Comparative Example 4), while the degradation rate increased significantly at 500 r / min (Example 9) and 600 r / min (Example 10). This indicates that under the short ball milling conditions of this application, the rotation speed plays a dominant role in the degradation rate, and only high rotation speed can obtain a better degradation effect.

[0072] Depend on Figure 5It can be seen that under the condition of pH=2 (Example 12), the removal rate of clofibrate was the highest in the initial 1-3 min of the reaction; while under the conditions of pH=4 (Example 13), pH=8 (Example 14), and pH=10 (Example 15), the catalytic degradation effect of clofibrate decreased compared with the original pH=6.

[0073] (2) Degradation of methylene blue solution Example 18: The catalyst using polyferric sulfate as the iron source showed high and similar degradation efficiency for both potassium persulfate and potassium perdisulfate, with degradation rates exceeding 82%; however, hydrogen peroxide's efficiency decreased in the later stages of the reaction, with a final degradation rate of only 61.52%. Figure 6 a). In Example 16, the catalyst using ferrous sulfate as the iron source showed a degradation rate of around 82% for hydrogen peroxide, while the rate of degradation slowed down and was lower in the later stages of the reaction, with a degradation rate of only 75.46%. Figure 6 b). In Example 17, the catalyst using iron acetylacetone as the iron source achieved a 75% degradation rate for persulfate, while hydrogen peroxide only achieved 57.39% ( Figure 6 c).

[0074] from Figure 7 As can be seen, in the initial stage of the reaction, the degradation rate is directly proportional to the amount of catalyst added; the larger the amount of catalyst added, the higher the degradation efficiency within the same time period. Subsequently, in the middle stage of the reaction, the group with a larger amount of catalyst added showed a greater degree of degradation and reached the reaction endpoint earlier. In the final stage of the reaction, all three amounts of catalyst added were able to degrade methylene blue to a low level, with the highest degradation rate reaching 99.04%.

[0075] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. 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 claims of the present invention.

Claims

1. A method for preparing an iron oxide-molybdenum disulfide heterojunction catalyst, characterized in that, Includes the following steps: S1. Dissolve and disperse molybdate and sulfur-containing compounds; S2. The resulting mixed solution is ball-milled. S3. Perform the first hydrothermal reaction on the ball-milled mixture; S4. A second hydrothermal process is performed in the presence of iron salts to obtain the iron oxide-molybdenum disulfide heterojunction catalyst. The iron salt is added to the system at least in one of the stages before the first hydrothermal reaction and before the second hydrothermal reaction.

2. The preparation method of the iron oxide-molybdenum disulfide heterojunction catalyst according to claim 1, characterized in that, The molar ratio of molybdenum in the molybdate to sulfur in the sulfur-containing compound described in S1 is 1:4~8.

3. The method for preparing the iron oxide-molybdenum disulfide heterojunction catalyst according to claim 1, characterized in that, During S2 ball milling, the rotation speed is 400~700 r / min and the milling time is 60~120 min.

4. The method for preparing the iron oxide-molybdenum disulfide heterojunction catalyst according to claim 1, characterized in that, After adding iron salt to S4, the mass ratio of molybdenum to iron in the system is 1~10:

1.

5. An iron oxide-molybdenum disulfide heterojunction catalyst, characterized in that, It is prepared by the method for preparing the iron oxide-molybdenum disulfide heterojunction catalyst according to any one of claims 1 to 4.

6. The application of the iron oxide-molybdenum disulfide heterojunction catalyst according to claim 5, characterized in that, Used for catalytic oxidation reactions.

7. The application of the iron oxide-molybdenum disulfide heterojunction catalyst according to claim 6, characterized in that, Antibiotic-like organic pollutants in water are degraded by catalytic oxidants.

8. A method for degrading antibiotic-like organic pollutants in water, characterized in that, The iron oxide-molybdenum disulfide heterojunction catalyst of claim 5 is used.

9. The method for degrading antibiotic-like organic pollutants in water according to claim 8, characterized in that, The dosage of the iron oxide-molybdenum disulfide heterojunction catalyst in water is 0.1~0.3 g / L.

10. The method for degrading antibiotic-like organic pollutants in water according to claim 8, characterized in that, The pH of the reaction system for degrading antibiotic-like organic pollutants in water is 2-10.

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