Iron mud-based modified copper sulfide persulfate catalyst, preparation method and application

Abstract

The invention relates to the technical field of water treatment, and particularly discloses an iron-mud-based modified copper sulfide persulfate catalyst, a preparation method and application. The catalyst is synthesized by adopting a solvothermal reaction method, polyvinylpyrrolidone is taken as a surfactant to regulate and control the morphology of metal sulfide, a flower-shaped nanosphere structure is formed, pretreated iron-containing sludge of a municipal sewage treatment plant is introduced, and a composite material with bimetal and sulfur multi-element active sites is constructed; the preparation process is simple and convenient, the cost is low, resource utilization of the waste iron mud is realized, refractory organic pollutants such as iohexol in a water body can be efficiently degraded, good catalytic performance is shown in the pH range of 3-11, good cycle stability and adaptability to different water qualities are achieved, and the method is suitable for industrial production. And an efficient and low-carbon technical scheme is provided for advanced sewage treatment.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to iron mud-based modified copper sulfide persulfate catalyst, its preparation method, and its application. Background Technology

[0002] The persulfate advanced oxidation process has attracted widespread attention in the treatment of recalcitrant organic wastewater due to its ability to generate highly oxidizing sulfate radicals. Commonly used single transition metal sulfides, such as copper sulfide (CuS), show great potential due to their unique electronic properties and abundant active sites. However, CuS catalysts prepared by traditional methods generally suffer from insufficient exposure of active sites, poor structural stability, and easy leaching of metal ions during the reaction process. This results in insufficient oxide species generated by persulfate activation, severely restricting its practical application and widespread adoption.

[0003] To overcome the aforementioned limitations, existing technologies attempt to regulate the microstructure of catalysts through surfactant modification. One approach involves using surfactants (such as polyvinylpyrrolidone, PVP) in the material synthesis process. For example, Chinese patent CN120169341A discloses a method for preparing ultrathin CeO2 nanosheets using surfactants. By controlling the amount of surfactant, the catalyst can be transformed from multilayer nanosheets to an ultrathin structure, thereby increasing the specific surface area and the number of active sites. However, this method only focuses on morphology regulation and does not address the issues of metal leaching and stability. On the other hand, structural stability and catalytic performance can be enhanced by constructing bimetallic synergistic systems or introducing support materials. Meanwhile, iron-containing sludge from municipal wastewater treatment plants is rich in iron oxides. If this waste resource can be used as an iron source or support for catalysts, the recycling of waste resources can be achieved. However, how to effectively combine iron sludge with metal sulfides and maximize the exposure of active sites through morphology regulation remains a gap in current technology.

[0004] Therefore, there is an urgent need to develop a new type of catalyst that combines high catalytic activity, good stability, and resource recycling characteristics to meet the demand for efficient and low-carbon technologies in the deep treatment of wastewater. Summary of the Invention

[0005] This invention aims to provide an iron sludge-based modified copper persulfate catalyst, its preparation method, and its application. By controlling the surface micromorphology of metal sulfides with polyvinylpyrrolidone to form a flower-like nanosphere structure, and adding pretreated iron-containing sludge from municipal wastewater treatment plants during the hydrothermal synthesis process, a catalyst with bimetallic and sulfur-containing multi-functional active sites is constructed, which significantly improves the activation efficiency of persulfate.

[0006] On the one hand, the preparation method of the iron mud-based modified copper sulfide persulfate catalyst provided by the present invention adopts the following technical solution:

[0007] The preparation method of iron mud-based modified copper sulfide persulfate catalyst includes the following steps:

[0008] S1. Dissolve polyvinylpyrrolidone in ethylene glycol-pure water, then add thioacetamide and copper sulfate pentahydrate, and dissolve to obtain a mixed solution;

[0009] S2. Take the iron agent raw material powder and add it to the mixed solution obtained in step S1 and stir it evenly to carry out the hydrothermal synthesis reaction. After the reaction is completed, cool it to obtain the precipitate.

[0010] S3. The precipitate obtained in step S2 is repeatedly washed with ethanol and pure water and centrifuged. After vacuum drying, it is ground to obtain iron mud-based modified copper sulfide persulfate catalyst.

[0011] Preferably, in step S1, the volume ratio of ethylene glycol to pure water is 1:3.

[0012] Preferably, in step S1, the mass ratio of copper sulfate pentahydrate to polyvinylpyrrolidone is 1:(0.09~0.32).

[0013] The molar ratio of copper sulfate pentahydrate to thioacetamide is 1:(0.75~1).

[0014] Preferably, the iron agent raw material powder in step S2 includes the following preparation steps:

[0015] Iron sludge cake from a municipal sewage treatment plant is dried at 100-150℃ for more than 24 hours, then ground through a 200-mesh sieve, and hydrated at 100℃ for 8-24 hours to obtain iron agent raw material powder.

[0016] Preferably, the mass ratio of the iron agent raw material powder to copper sulfate pentahydrate is (4.2 × 10⁻⁶). -3 ~ 4.1×10 -2 ):1.

[0017] Preferably, the hydrothermal synthesis reaction process in step S2 involves placing the mixed solution in a high-pressure reactor, and then placing the high-pressure reactor in an oven at 100~120℃ for 15~18 h.

[0018] Preferably, the vacuum drying conditions in step S3 are: drying at 60~80℃ for 12~24 h.

[0019] On the other hand, the present invention also provides an iron mud-based modified copper sulfide persulfate catalyst prepared by any of the above preparation methods, wherein the iron mud-based modified copper sulfide persulfate catalyst has a flower-like nanosphere structure.

[0020] Furthermore, this invention also provides the application of the iron mud-based modified copper sulfide persulfate catalyst prepared by any of the above-mentioned methods, specifically adopting the following scheme:

[0021] An application of an iron mud-based modified copper sulfide persulfate catalyst prepared by the above preparation method in wastewater treatment involves adding the iron mud-based modified copper sulfide persulfate catalyst to water containing iohexol, stirring until homogeneous, and then adding persulfate.

[0022] Preferably, the concentration of the iron mud-based modified copper sulfide persulfate catalyst is 0.15~0.4 g / L;

[0023] The persulfate is a potassium peroxymonosulfate complex salt, and the concentration of the persulfate is 0.02~0.04 g / L.

[0024] In summary, the beneficial effects of the present invention are as follows:

[0025] 1. This invention successfully constructed a composite material with a flower-like nanosphere structure and bimetallic active sites by controlling the morphology of polyvinylpyrrolidone and introducing iron raw material powder. When activating persulfate, this catalyst exhibits excellent catalytic activity and stability, and can continuously and efficiently generate active species such as sulfate radicals and hydroxyl radicals. It can rapidly degrade recalcitrant organic pollutants (such as iohexol) in a wide pH range (pH 3-11), with a removal rate of up to 100% within 10 minutes, and its performance remains stable after being recycled 4 times.

[0026] 2. This invention achieves the goals of "treating waste with waste" and resource recycling. Utilizing iron-containing sludge from municipal wastewater treatment plants as a low-cost iron source significantly reduces catalyst costs while simultaneously providing a high-value utilization pathway for solid waste. The preparation process is simple and the conditions are mild. The resulting catalyst is highly adaptable, maintaining efficient degradation capabilities in various actual water bodies such as tap water, river water, and lake water. This provides an economical, efficient, and environmentally friendly technical solution for the deep treatment of recalcitrant organic wastewater. Attached Figure Description

[0027] Figure 1 In Figure a, the image is a scanning electron microscope image of the catalyst prepared in Comparative Example 2.

[0028] Figure 1 Figure b is a magnified scanning electron microscope image of the catalyst prepared in Comparative Example 2;

[0029] Figure 1 In Figure c, the image is a scanning electron microscope image of the catalyst prepared in Comparative Example 1.

[0030] Figure 1In the image d, it is a magnified scanning electron microscope image of the catalyst prepared in Comparative Example 1.

[0031] Figure 1 Image e is a scanning electron microscope image of the catalyst prepared in Example 1;

[0032] Figure 1 Image f is a magnified scanning electron microscope image of the catalyst prepared in Example 1;

[0033] Figure 1 Image g is a scanning electron microscope image of the catalyst prepared in Example 2;

[0034] Figure 1 In the image, h is a magnified scanning electron microscope image of the catalyst prepared in Example 2;

[0035] Figure 2 The graph shows a comparison of the degradation performance of iohexol by the catalysts prepared in Examples 1-2 and Comparative Examples 1-2.

[0036] Figure 3 This is a comparison of the degradation performance of the catalyst prepared in Example 1 on iohexol solutions with different pH values;

[0037] Figure 4 The graph shows the reusability performance of the catalyst prepared in Example 1.

[0038] Figure 5 The graph shows the degradation effect of the catalyst prepared in Example 1 on iohexol in different water bodies. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to embodiments, comparative examples, test examples and accompanying drawings.

[0040] Example

[0041] Example 1

[0042] The preparation method of iron mud-based modified copper sulfide persulfate catalyst, the specific steps are as follows:

[0043] 1) Air-dry the iron sludge cake from the coagulation section of the municipal sewage treatment plant for at least 2 days, crush it, put it in a forced-air drying oven at 105℃ for 24 hours, grind it with a mortar and pestle and pass it through a 200-mesh sieve, and hydrate it at 100℃ for 8-24 hours to obtain iron agent raw material powder.

[0044] 2) Take ethylene glycol and pure water in a volume ratio of 1:3, mix them to prepare 40 mL of ethylene glycol-pure water solution, add 0.2 g of polyvinylpyrrolidone (PVP) and stir thoroughly to dissolve, then add 0.37 g of thioacetamide and 1.24 g of copper sulfate pentahydrate, and dissolve thoroughly to obtain a mixed solution;

[0045] 3) Add 20 mg of iron raw material powder obtained in step 1) to the mixed solution in step 2), stir evenly, and then transfer it to a 100 mL polytetrafluoroethylene-lined high-pressure reactor. Then place the high-pressure reactor in an oven at 100°C and react for 18 h.

[0046] 4) After the reaction is complete, remove the high-pressure reactor from the oven, cool it and remove the precipitate. Wash it repeatedly with ethanol and pure water at least 3 times. After centrifugation, vacuum drying at 60 ℃ for 12 h and grinding, black CuS material is obtained, which is denoted as PVP-CuS@Fe-20, i.e., iron mud-based modified copper sulfide persulfate catalyst with bimetallic and sulfur-containing multi-element active sites.

[0047] Example 2

[0048] The preparation method of the iron mud-based modified copper sulfide persulfate catalyst differs from that of Example 1 in that the amount of iron raw material powder added in step 3) is 100 mg, and the resulting catalyst is denoted as PVP-CuS@Fe-100. The remaining steps are the same as those in Example 1.

[0049] Comparative Example

[0050] Comparative Example 1

[0051] A method for preparing a modified copper metal sulfide persulfate catalyst includes the following steps:

[0052] 1) Take ethylene glycol and pure water in a volume ratio of 1:3, mix them to prepare 40 mL of ethylene glycol-pure water solution, add 0.2 g of polyvinylpyrrolidone and stir thoroughly to dissolve, then add 0.37 g of thioacetamide and 1.24 g of copper sulfate pentahydrate, and dissolve thoroughly to obtain a mixed solution.

[0053] 2) Transfer the mixed solution obtained in step 1) into a 100 mL polytetrafluoroethylene-lined high-pressure reactor, and then place the high-pressure reactor in an oven at 100 °C for 18 h.

[0054] 3) After the reaction is completed, the high-pressure reactor is removed from the oven, cooled and the precipitate is removed. It is washed repeatedly with ethanol and pure water at least 3 times, centrifuged, vacuum dried at 60 ℃ for 12 h, and ground to obtain black CuS material, which is denoted as PVP-CuS, i.e. modified copper persulfate metal catalyst.

[0055] Comparative Example 2

[0056] A method for preparing a copper persulfate metal sulfide catalyst, which differs from Comparative Example 1 in that polyvinylpyrrolidone is not added, and the resulting catalyst is denoted as CuS. The remaining steps are the same as those in Comparative Example 1.

[0057] Reference Figure 1 , Figure 1 In Figures a and b, scanning electron microscope images of the catalyst prepared in Comparative Example 2 are shown. Figure 1 c and d are scanning electron microscope images of the catalyst prepared in Comparative Example 1; Figure 1 In Figures e and f, the images are scanning electron microscope images of the catalyst prepared in Example 1. Figure 1 In the image, g and h are scanning electron microscope images of the catalyst prepared in Example 2. Figure 1 As can be seen from Figures a and b, the CuS in Comparative Example 2 without the addition of polyvinylpyrrolidone is mainly composed of a plate-like structure, with nanospheres randomly dispersed on the surface of the nanoplates. Figure 1 c and d show that the addition of polyvinylpyrrolidone in Comparative Example 1 caused a huge change in the morphology of CuS, transforming it from a disordered plate-like structure into a more uniform flower-like nanosphere structure. Figure 1 Figures e and f show that the iron sludge in Example 1 has small micro-particles that are uniformly dispersed and adhere to the edge sheet of PVP-CuS. Figure 1 In Example 2, as the amount of iron sludge added increases, the particle distribution becomes more compact, forming more complex agglomerates.

[0058] Test case

[0059] Test Example 1

[0060] The catalysts prepared in Examples 1-2 and Comparative Examples 1-2 were tested for iohexol degradation in a potassium persulfate complex salt (PMS) system, including the following steps:

[0061] 1) Prepare four 100 mL solutions of iohexol with an initial concentration of 1 mg / L, and adjust the pH to 7 with 0.1 M hydrochloric acid and NaOH solution respectively; weigh the catalysts prepared by Example 1, Example 2, Comparative Example 1 and Comparative Example 2 and add them to the four iohexol solutions respectively, with a final concentration of 100 mg / L of catalyst in each iohexol solution;

[0062] 2) Add PMS to the four groups of iohexol solutions containing the catalyst from step 1) to a final concentration of 20 mg / L, and stir at 350 rpm to start the catalytic degradation reaction;

[0063] 3) Simultaneously, at specific time points (starting from the initiation of the catalytic degradation reaction, based on the degradation stage characteristics of iohexol, several time points representing the initial (rapid reaction stage), middle, and late (reaction approaching completion stage) stages are selected; in this embodiment, these are specifically 5 minutes, 15 minutes, 30 minutes, and 60 minutes), 2 mL samples are taken from the four groups of iohexol solutions that started catalytic degradation in step 2), and the reaction is immediately quenched with 50 μL of methanol. Then, the samples are filtered through a 0.22 μm PES filter membrane to remove residual catalyst, and stored in 1.5 mL brown liquid chromatography vials. Finally, the residual concentration of pollutants is detected by high performance liquid chromatography.

[0064] Reference Figure 2 In Comparative Example 2, the degradation of iohexol by CuS without PVP modification was extremely limited; in Comparative Example 1, the removal efficiency reached 80.3% when the PVP addition was 0.2 g; in Example 1, the system exhibited the best degradation effect when the iron raw material powder content was 20 mg, with an iohexol degradation rate as high as 99.3%; Example 2 showed that the removal rate decreased with the increase of iron raw material powder content, possibly because excessive iron sludge weakened the bimetallic valence state cycle effect.

[0065] Test Example 2

[0066] The degradation effect of the catalyst prepared in Example 1 on iohexol at different reaction pH was tested, including the following steps:

[0067] 1) Prepare five groups of 100 mL iohexol solutions with a concentration of 1 mg / L and pH values ​​of 3, 5, 7, 9 and 11 respectively. The final concentration of the catalyst is 150 mg / L. Take five portions of the catalyst prepared in Example 1 and add them to the five groups of iohexol solutions respectively. The final concentration of the catalyst in each group of iohexol solutions is 150 mg / L.

[0068] 2) Add PMS to the five groups of iohexol solutions containing the catalyst in step 1) to a final concentration of 20 mg / L, and stir at 350 rpm to start the catalytic degradation reaction;

[0069] 3) Simultaneously, at specific time points (starting from the initiation of the catalytic degradation reaction, based on the degradation stage characteristics of iohexol, several time points representing the initial (rapid reaction stage), middle, and late (reaction approaching completion stage) stages are selected; in this embodiment, these are specifically 5 minutes, 15 minutes, 30 minutes, and 60 minutes), 2 mL samples are taken from the five groups of iohexol solutions that started catalytic degradation in step 2), and the reaction is immediately quenched with 50 μL of methanol. Then, the samples are filtered through a 0.22 μm PES filter membrane to remove residual catalyst, and stored in 1.5 mL brown liquid chromatography vials. Finally, the residual concentration of pollutants is detected by high performance liquid chromatography.

[0070] Reference Figure 3 When pH ≤ 7, the PVP-CuS@Fe / PMS system in Example 1 achieved >99.3% degradation of iohexol within 30 min; when pH = 9 and 11, the IOH removal rate decreased to 84.5% and 74.9%, respectively. This may be due to the electrostatic repulsion between the negative charge on the catalyst surface and PMS ions inhibiting PMS adsorption, while OH... - It undergoes a quenching reaction with free radicals, leading to a decrease in the effective concentration of free radicals.

[0071] Test Example 3

[0072] The reusability of the catalyst prepared in Example 1 was tested, including the following steps:

[0073] 1) The catalyst prepared in Example 1 was added to 100 mL of 1 mg / L iohexol solution with a pH of 7, and the final concentration of the catalyst was 150 mg / L.

[0074] 2) Add PMS to the iohexol solution from step 1) to a final concentration of 20 mg / L, and stir at 350 rpm to begin the catalytic degradation reaction;

[0075] 3) Simultaneously, at specific time points (starting from the start of the catalytic degradation reaction, based on the degradation stage characteristics of iohexol, several time points representing the initial stage (rapid reaction stage), middle stage, and late stage (reaction approaching completion stage) are selected, specifically 5 minutes, 15 minutes, 30 minutes, and 60 minutes in this embodiment), 2 mL of sample is taken from the iohexol solution where catalytic degradation began in step 2), and the reaction is immediately quenched with 50 μL of methanol. Then, the sample is filtered through a 0.22 μm PES filter membrane to remove residual catalyst, and stored in 1.5 mL brown liquid chromatography vials. The residual concentration of pollutants is then detected by high performance liquid chromatography.

[0076] 4) After each reaction, the catalyst is collected by centrifugation and regenerated by washing with deionized water and ethanol alternately. The catalyst is then used for subsequent cyclic degradation tests.

[0077] Reference Figure 4 After four cycles of reuse, the PVP-CuS@Fe / PMS system in Example 1 still maintained a removal rate of iohexol of over 93.6%, demonstrating strong cyclic stability.

[0078] Test Example 4

[0079] The degradation efficiency of the catalyst prepared in Example 1 on iohexol in actual water bodies was tested, including the following steps:

[0080] 1) Water samples were obtained from ultrapure water, tap water, river water, secondary effluent from sewage treatment plant and river water respectively, and 100 mL of 1 mg / L iohexol initial solution was prepared for each. 15 mg of the catalyst sample prepared in Example 1 was weighed and added to the iohexol initial solution.

[0081] 2) Add PMS to the iohexol solution containing the catalyst in step 1) until the final concentration is 20 mg / L, and stir at 350 rpm to start the catalytic degradation reaction;

[0082] 3) Simultaneously, at specific time points (starting from the initiation of the catalytic degradation reaction, based on the degradation stage characteristics of iohexol, several time points representing the initial stage (rapid reaction stage), middle stage, and late stage (reaction approaching completion stage) are selected; in this embodiment, these are specifically 5 minutes, 15 minutes, 30 minutes, and 60 minutes), 2 mL of sample is taken out, and the reaction is immediately quenched with 50 μL of methanol. Then, the sample is filtered through a 0.22 μm PES filter membrane, and the residual concentration of pollutants is detected by high performance liquid chromatography.

[0083] Reference Figure 5 The catalyst prepared in Example 1 achieved iohexol removal rates of 90.5%, 85.9%, 84.2%, and 81.3% in ultrapure water, tap water, river water, secondary effluent from sewage treatment plants, and river water, respectively. The concentration of dissolved organic matter in the water matrix may affect the actual efficiency of the system, but this catalytic material can still maintain high adaptability in complex water conditions.

[0084] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing iron mud-based modified copper sulfide persulfate catalyst, characterized in that, Includes the following steps: S1. Dissolve polyvinylpyrrolidone in ethylene glycol-pure water, then add thioacetamide and copper sulfate pentahydrate, and dissolve to obtain a mixed solution; S2. Take the iron agent raw material powder and add it to the mixed solution obtained in step S1 and stir it evenly to carry out the hydrothermal synthesis reaction. After the reaction is completed, cool it to obtain the precipitate. S3. The precipitate obtained in step S2 is repeatedly washed with ethanol and pure water and centrifuged. After vacuum drying, it is ground to obtain iron mud-based modified copper sulfide persulfate catalyst.

2. The preparation method of the iron mud-based modified copper sulfide persulfate catalyst according to claim 1, characterized in that, In step S1, the volume ratio of ethylene glycol to pure water is 1:

3.

3. The preparation method of the iron mud-based modified copper sulfide persulfate catalyst according to claim 1, characterized in that, In step S1, the mass ratio of copper sulfate pentahydrate to polyvinylpyrrolidone is 1:(0.09~0.32). The molar ratio of copper sulfate pentahydrate to thioacetamide is 1:(0.75~1).

4. The preparation method of the iron mud-based modified copper sulfide persulfate catalyst according to claim 1, characterized in that, The iron agent raw material powder in step S2 includes the following preparation steps: Iron sludge cake from a municipal sewage treatment plant is dried at 100-150℃ for more than 24 hours, then ground through a 200-mesh sieve, and hydrated at 100℃ for 8-24 hours to obtain iron agent raw material powder.

5. The preparation method of the iron mud-based modified copper sulfide persulfate catalyst according to claim 4, characterized in that, The mass ratio of the iron agent powder to copper sulfate pentahydrate is (4.2 × 10⁻⁶). -3 ~ 4.1×10 -2 ):

1.

6. The method for preparing the iron mud-based modified copper sulfide persulfate catalyst according to claim 1, characterized in that, The hydrothermal synthesis reaction process in step S2 involves placing the mixed solution in a high-pressure reactor, and then placing the high-pressure reactor in an oven at 100-120°C for 15-18 hours.

7. The preparation method of the iron mud-based modified copper sulfide persulfate catalyst according to claim 1, characterized in that, The vacuum drying conditions in step S3 are: drying at 60~80℃ for 12~24 h.

8. An iron mud-based modified copper sulfide persulfate catalyst prepared by any one of the preparation methods described in claims 1-7, characterized in that, The iron mud-based modified copper sulfide persulfate catalyst has a flower-like nanosphere structure.

9. The application of an iron mud-based modified copper sulfide persulfate catalyst prepared by any one of the preparation methods described in claims 1-7 in wastewater treatment, characterized in that, Iron mud-based modified copper sulfide persulfate catalyst was added to water containing iohexol, and after stirring evenly, persulfate was added.

10. The application of the iron mud-based modified copper sulfide persulfate catalyst according to claim 9 in wastewater treatment, characterized in that, The concentration of the iron mud-based modified copper sulfide persulfate catalyst added is 0.15~0.4 g / L; The persulfate is a potassium peroxymonosulfate complex salt, and the concentration of the persulfate is 0.02~0.04 g / L.

Images