Preparation method and application of MXene loaded iron nanoparticle composite

Abstract

The application discloses an MXene loaded iron nanoparticle composite material, a preparation method and application thereof, and relates to the technical field of water pollution treatment. A multilayer MXene suspension is mixed with iron nitrate for reaction, and after precipitation, filtration and drying, the mixture is mixed with dicyandiamide, and two-step high-temperature calcination is carried out under a nitrogen atmosphere. The catalyst is prepared through cooling, washing and drying. The material has good dispersity and high activity, can efficiently activate peroxymonosulfate to degrade chlorophenol pollutants, and the degradation rate is more than 99% within 20 minutes, and is suitable for deep treatment of industrial refractory organic wastewater.

Description

Technical Field

[0001] This invention relates to the field of water pollution control technology, specifically to a method for preparing and applying a layered MXene-supported iron nanoparticle composite material. Background Technology

[0002] Industrial production processes generate large amounts of recalcitrant organic wastewater, among which chlorophenols are widely derived from wastewater discharges from industries such as chemicals, pesticides, pharmaceuticals, papermaking, and wood preservation. These pollutants are highly toxic, difficult to biodegrade, have strong bioaccumulation properties, and pose teratogenic, carcinogenic, and mutagenic risks. They are typical persistent organic pollutants, with long residual periods in natural water bodies, and are difficult to remove effectively through conventional biological and chemical treatments. They easily penetrate wastewater treatment systems and enter the aquatic environment, posing a long-term potential threat to ecosystems and human health.

[0003] Traditional water treatment processes (coagulation sedimentation, biological methods, and conventional oxidation) have low removal efficiency and poor mineralization of chlorophenol pollutants, and easily generate more toxic chlorine-containing byproducts, failing to meet the requirements for deep purification. Advanced oxidation technologies (AOPs), with their highly reactive oxidizing species, can efficiently mineralize recalcitrant organic matter, making them the mainstream technology for the deep treatment of industrial chlorophenol wastewater. Among them, persulfate (PMS) activation technology has received widespread attention due to its strong oxidizing power, good stability, wide applicable pH range, and environmentally friendly reduction products.

[0004] Transition metal catalysis is a highly efficient pathway for activating PMS. Traditional iron-based materials are low-cost and environmentally friendly, but suffer from problems such as easy aggregation, poor stability, metal dissolution, and limited catalytic efficiency. Iron nanoparticles have advantages such as large specific surface area, high reactivity, and fast electron transfer, but they are prone to oxidation and aggregation, which limits their practical applications. MXene, as a novel two-dimensional layered material, has the characteristics of high conductivity, large specific surface area, abundant surface functional groups, and tunable structure, making it an ideal carrier that can effectively disperse iron nanoparticles, inhibit aggregation, promote electron transfer, and improve catalytic stability and activity.

[0005] Existing research on MXene-based iron catalysts mainly focuses on single atoms or ordinary iron oxides. However, there are still shortcomings in the design, preparation, and application of MXene-supported iron nanoparticles for the efficient degradation of industrial chlorophenol wastewater, such as complex preparation processes, insufficient stability, weak anti-interference ability, and limited mineralization efficiency. Therefore, developing an MXene-supported iron nanoparticle composite material with a simple preparation process, high catalytic activity, good stability, resistance to complex water quality interference, and efficient activation of PMS for the degradation of chlorophenol pollutants in industrial wastewater has significant engineering application value and practical significance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, such as the high toxicity and recalcitrant nature of industrial chlorophenol wastewater, low removal efficiency of conventional processes, the tendency of traditional iron-based catalysts to agglomerate, poor stability, metal leaching, and insufficient mineralization, the easy oxidation and deactivation of iron nanoparticles, and poor dispersibility, as well as the weak anti-interference ability and complex preparation process of existing MXene-based iron catalysts in complex industrial water conditions, this invention provides an MXene-supported iron nanoparticle material, its preparation method, and its application in the activation of persulfate for the degradation of chlorophenol pollutants in industrial wastewater. This invention aims to solve the problems of low activity, poor stability, weak anti-interference ability, high preparation cost, and easy secondary pollution of existing catalysts. It provides a novel MXene-based catalytic material with a simple preparation process, high catalytic activity, good stability, resistance to complex water quality interference, high mineralization efficiency, and efficient activation of persulfate for the degradation of chlorophenol pollutants in industrial wastewater, providing technical support for the deep treatment of recalcitrant organic wastewater.

[0007] To achieve the above objectives, the present invention provides the following technical solution.

[0008] This invention provides a method for preparing MXene-supported iron nanoparticle composite materials, comprising the following steps.

[0009] (1) Mix the multilayer MXene suspension with ferric nitrate, disperse it by ultrasonication, and then stir to react to obtain a precursor mixture.

[0010] (2) The mixture obtained in step (1) is allowed to stand and precipitate, and then filtered to separate the complex.

[0011] (3) After drying and grinding the complex obtained in step (2), dicyandiamide is added and calcined at high temperature; after cooling the calcined product, it is washed with ultrapure water until neutral and then dried to obtain the composite material.

[0012] Preferably, the concentration of the suspension in step (1) is 6~10 g / L; the mass ratio of ferric nitrate to MXene is (0.5~1):1.

[0013] Preferably, in step (1), the ultrasonic dispersion time is 20~40 min; the stirring reaction temperature is 20~30℃; and the reaction time is 0.5~2 h.

[0014] Preferably, in step (2), the settling time is 6~12h.

[0015] Preferably, in step (3), the drying temperature is 60~80℃; the mass ratio of the complex to dicyandiamide is 1:(5~15); the calcination is carried out under a nitrogen atmosphere, the heating rate is 3~8℃ / min, first heating to 500~600℃ and holding for 0.5~1.5h, then heating to 900~1000℃ and holding for 0.5~1.5h.

[0016] This invention provides an MXene-loaded iron nanoparticle composite material prepared by the above-described preparation method.

[0017] This invention also provides the application of the MXene-supported iron nanoparticle composite material described above in the degradation of chlorophenol pollutants in industrial wastewater by activated persulfate.

[0018] The two-dimensional layered MXene support in this invention possesses a large specific surface area and abundant surface functional groups, which can effectively anchor and disperse iron nanoparticles, significantly inhibiting their aggregation and oxidation, and improving the exposure rate of active sites. During the activation of persulfate to degrade chlorophenol pollutants, the excellent conductivity of MXene accelerates electron transport efficiency and enhances catalytic performance. Dicyandiamide, during high-temperature calcination, serves as a nitrogen source to achieve nitrogen doping of the material, while the resulting carbon-based structure further improves the material's conductivity and specific surface area, providing a pathway for the diffusion of pollutant molecules and persulfate, thus enhancing reaction efficiency. The prepared composite catalyst exhibits good dispersibility and high catalytic activity. The results of the examples show that the MXene-supported iron nanoparticle composite material prepared in this invention achieves a degradation rate of over 99.5% when activating persulfate to degrade 2,4-dichlorophenol in industrial wastewater, demonstrating excellent catalytic performance and application prospects.

[0019] Attached image description.

[0020] Figure 1 The images show the X-ray diffraction results of the materials used in the examples and comparative examples.

[0021] Figure 2 The image shows the scanning electron microscope (SEM) results of the MXene-loaded iron nanoparticle composite material prepared in an embodiment of the present invention.

[0022] Figure 3 The graph shows the adsorption performance test results of the catalysts prepared in the examples and comparative examples.

[0023] Figure 4 The graph shows the test results of the catalysts prepared in the examples and comparative examples for activating persulfate to degrade the target pollutants. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are merely all other embodiments obtained by those skilled in the art without creative effort, and all fall within the scope of protection of the present invention.

[0025] In the following embodiments, the multilayer MXene is a multilayer Ti3C2 powder.

[0026] Unless otherwise specified, the present invention does not impose any special restrictions on the source of the raw materials, and commercially available products well known to those skilled in the art can be used.

[0027] Example: (1) Disperse 2g of multilayer Ti3C2 powder in 250ml of ultrapure water to prepare an MXene suspension with a concentration of 8g / L; add ferric nitrate to the MXene suspension according to the mass ratio of ferric nitrate to MXene of 0.72:1, sonicate for 30min, and then stir and react for 1h at 25℃ to obtain a precursor mixture.

[0028] (2) The precursor mixture was allowed to stand for 12 hours to precipitate, and then filtered to obtain the complex.

[0029] (3) The complex was dried at 80°C for 12 hours and then ground to obtain powder. The powder and dicyandiamide were mixed evenly according to the mass ratio of complex to dicyandiamide of 1:10. The mixture was placed in a tube furnace and heated to 550°C for 1 hour at a heating rate of 5°C / min under a nitrogen atmosphere. Then the temperature was increased to 950°C and held for 1 hour. The mixture was then cooled to room temperature and washed with ultrapure water until neutral. The mixture was dried and ground to obtain the composite material.

[0030] The difference between the examples and the comparative examples is that the comparative examples are multilayer Ti3C2 powders that have not undergone any treatment.

[0031] X-ray diffraction patterns of the examples and comparative materials.

[0032] Depend on Figure 1 As can be seen, the catalyst material prepared in the embodiments of the present invention exhibits clear and strong characteristic diffraction peaks at 2θ≈44.7° and 65°. This result confirms that, after preparation by the process of the present invention, the iron species are effectively reduced and a well-crystallized iron crystal phase is formed. The comparative sample only exhibits the characteristic peak of Ti3C2.

[0033] Scanning electron microscope images of the embodiment.

[0034] The catalyst material prepared in the examples maintained the typical layered stacked structure of MXene, with clear sheet edges, intact interlayer structure, and no obvious interlayer collapse or agglomeration. Meanwhile, fine particles were distributed on the material surface, indicating that zero-valent iron nanoparticles were successfully loaded onto the MXene sheets and exhibited good dispersion without severe agglomeration.

[0035] This layered structure and surface particle distribution are beneficial for increasing the specific surface area of ​​the material and exposing more catalytic active sites. At the same time, the two-dimensional layered structure of MXene can provide stable support for zero-valent iron, inhibit its aggregation and oxidation, and provide a structural basis for the subsequent efficient activation of persulfate.

[0036] Adsorption performance test.

[0037] Depend on Figure 3 It can be seen that within 0 to 5 minutes, the catalyst material prepared in the example adsorbs the target pollutant at a significantly faster rate, and its Cᵢ / C0 value drops rapidly to about 0.82; while the Cᵢ / C0 value of the comparative example only drops slowly to about 0.93, indicating that the initial adsorption driving force of the prepared catalyst material is stronger.

[0038] When the reaction reached adsorption equilibrium after 20 minutes, the Cᵢ / CO value of the catalyst material prepared in the example was stable at about 0.73, indicating that its removal rate of pollutants was about 27%; while the Cᵢ / CO value of the comparative example was always maintained above 0.90, with a removal rate of less than 10%, indicating that the equilibrium adsorption capacity of the example was significantly higher.

[0039] The prepared catalyst material reached adsorption equilibrium in about 15 minutes, and the subsequent curve remained basically stable. The curve of the comparative example decreased slowly throughout the test period and never reached a clear equilibrium, indicating that its adsorption process was inefficient and kinetic.

[0040] Degradation performance test.

[0041] Depend on Figure 4 It is evident that the prepared catalyst material exhibits excellent catalytic activity, achieving almost complete degradation of pollutants within 20 minutes with a degradation rate exceeding 99%; while the comparative catalyst has extremely low degradation efficiency, with Ci / C0 remaining above 0.7 after 20 minutes, and a degradation rate of less than 30%, far lower than that of the example.

[0042] The degradation curve of the catalyst material prepared in the example showed a rapid downward trend, with an extremely fast degradation rate in the first 10 minutes, and the Cᵢ / C0 value rapidly decreased from 1.0 to about 0.28, followed by a slow degradation stage; the degradation curve of the comparative catalyst decreased slowly, with no obvious rapid degradation stage throughout the reaction, and its kinetic performance was far inferior to that of the example.

[0043] The above comparative results show that the preparation method of the present invention is crucial for constructing highly active catalytic sites, significantly improves the catalyst's ability to activate persulfate, and achieves efficient and rapid degradation of target pollutants, thus verifying the superiority of the technical solution of the present invention.

[0044] In summary, the catalyst prepared by this invention has better catalytic performance and a higher degradation rate of pollutants.

[0045] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing an MXene-supported iron nanoparticle composite material, comprising the following steps: (1) Mix the multilayer MXene suspension with ferric nitrate, disperse it by ultrasonication, and then stir to react to obtain the precursor mixture; (2) The mixture obtained in step (1) is allowed to stand and precipitate, and then filtered to separate the complex. (3) After drying and grinding the complex obtained in step (2), dicyandiamide is added and calcined at high temperature; after cooling the calcined product, it is washed with ultrapure water until neutral and then dried to obtain the composite material.

2. The preparation method according to claim 1, characterized in that, The concentration of the suspension in step (1) is 6~10 g / L; the mass ratio of ferric nitrate to MXene is (0.5~1):

1.

3. The preparation method according to claim 1, characterized in that, In step (1), the ultrasonic dispersion time is 20~40 min; the stirring reaction temperature is 20~30℃; and the reaction time is 0.5~2 h.

4. The preparation method according to claim 1, characterized in that, In step (2), the settling time is 6~12h.

5. The preparation method according to claim 1, characterized in that, In step (3), the drying temperature is 60~80℃; the mass ratio of the complex to dicyandiamide is 1:(5~15); the calcination is carried out under a nitrogen atmosphere, the heating rate is 3~8℃ / min, first heating to 500~600℃ and holding for 0.5~1.5h, then heating to 900~1000℃ and holding for 0.5~1.5h.

6. The application of the composite material prepared by the preparation method according to any one of claims 1 to 5 in the degradation of chlorophenol pollutants by activated persulfate.

Images