A method for preparing a Fe-based bifunctional monolithic catalyst based on dichloride water corrosion method and application thereof

Abstract

The application discloses a method for preparing Fe-based bifunctional monolithic catalyst based on a dichloride water corrosion method and application, and comprises the following steps: etching foamed iron in a dichloride (NaCl and MCl, M=Mn, Ni, Zn, Co, etc.) solution, and then performing heat treatment under the protection of an inert atmosphere to obtain a target catalyst material. The dichloride water corrosion strategy is adopted in combination with a heat treatment process, and the prepared catalyst has the advantages of structural stability and strong degradation capacity for organic pollutants, and the method has the advantages of simple process, low cost, environmental friendliness, good scalability and universality, and provides a new idea for innovative research of corrosion science, and has important significance in practical application of the Fe-based bifunctional monolithic catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a method for preparing Fe-based bifunctional monolithic catalysts based on the dichloride water corrosion method and its application in the treatment of organic pollutants. Background Technology

[0002] Currently, advanced oxidation reactions are considered an effective method for removing organic pollutants from wastewater. The principle involves the activation of periodate to generate a large amount of active oxidizing agents capable of degrading most organic pollutants. However, homogeneous catalysts are difficult to recover due to their water solubility and potential for secondary pollution, limiting their practical application. Therefore, heterogeneous periodate oxidation systems have gradually gained widespread attention due to their higher catalytic efficiency, better stability, and lower operating costs.

[0003] Generally, catalysts used for catalytic oxidation are classified into two categories based on their existing forms: powdered catalysts and self-supporting catalysts. However, powdered catalysts face problems such as easy loss and clogging, while self-supporting catalysts can effectively overcome these problems. Currently, commonly used self-supporting catalyst materials are mostly carbon-based materials, such as carbon paper, carbon felt, and carbon cloth. However, due to the steric hindrance effect between the substrate and the active material, the active sites are difficult to uniformly anchor on the material surface, affecting the catalytic performance. In addition, common methods for preparing self-supporting bimetallic (oxy) hydroxides include electrochemical deposition, ion exchange, and hydrothermal synthesis. These traditional preparation methods require special equipment and harsh reaction conditions, increasing production costs and environmental pollution, and limiting the promotion of Fenton-like reactions in practical applications. Patent CN 103951016A discloses a method for treating nitrogen-containing wastewater using an iron-carbon composite agent. This method uses activated carbon and ordinary iron powder for catalysis, but the catalytic efficiency is low, and the iron powder is easily oxidized, leading to deactivation. Patent CN 106229153A discloses a method for preparing a carbon cloth-supported nickel oxide-coated iron oxide nanorod composite material. This method uses a hydrothermal method to grow iron oxide nanorods on carbon cloth. However, the hydrothermal method requires a closed environment under certain pressure, making the preparation process complex, energy-intensive, and costly. Patent CN 111313041A discloses a method for preparing a nickel-iron hydroxide electrocatalyst. This method involves dissolving iron salts, fluorine-containing compounds, and urea in water, then immersing nickel foam in the solution and performing a hydrothermal reaction to obtain the nickel-iron hydroxide electrocatalyst. However, this method involves reacting the iron salt solution with the nickel foam substrate, resulting in the formation of nickel-iron hydroxide only on the nickel foam substrate with a limited surface area. This leads to a limited specific surface area and pore structure, low iron loading, and poor long-term stability. Therefore, developing a simple, economical, and environmentally friendly synthesis method for preparing self-supporting bimetallic (oxygen) hydroxides is urgently needed.

[0004] Metal corrosion is a common spontaneous process in the natural environment, often leading to severe material failure and engineering damage, resulting in significant economic losses. To prevent metal corrosion, numerous measures have been implemented, such as pigment coatings, electrochemical protection, and the addition of corrosion inhibitors. Despite significant progress in corrosion prevention, research on the functional utilization of corrosion phenomena remains relatively scarce. In recent years, inspired by the concept of "turning harm into benefit," the preparation of catalysts using corrosion processes has become an emerging research direction, providing an innovative perspective for the development of catalysis and other technologies. Corrosion methods exhibit high versatility and scalability due to their low requirements for energy input, temperature, pressure, and reactor configuration. As a novel strategy for catalyst synthesis, corrosion engineering offers significant advantages: simple synthesis processes, strong controllability, ease of large-scale production, and low cost. Therefore, corrosion engineering, as a promising technology for preparing highly efficient catalysts using the self-corrosion reaction of metallic materials, has significant research and development value. Summary of the Invention

[0005] To address the problems of complex synthesis conditions, limited large-scale application, and easy loss and clogging of powdered catalysts in existing catalysts, this invention provides a method for preparing Fe-based bifunctional monolithic catalysts based on the dichloride water corrosion method and its application. The aim is to make the prepared catalytic material structurally stable, highly active, and capable of efficiently degrading pollutants in wastewater at room temperature and atmospheric pressure.

[0006] To achieve its objectives, the present invention employs the following technical solution:

[0007] This invention first provides a method for preparing Fe-based bifunctional monolithic catalysts based on the dichloride water corrosion method, which is carried out according to the following steps:

[0008] Step 1: Immerse the foamed iron in dilute hydrochloric acid and ultrasonically clean it to remove oxides on the surface of the foamed iron. Then rinse it with ultrapure water to remove the residual dilute hydrochloric acid. Next, immerse the foamed iron in anhydrous ethanol for ultrasonic cleaning to remove organic contaminants on the surface of the foamed iron. After ultrasonic cleaning, rinse it with anhydrous ethanol again. Finally, dry it in an oven to obtain material A.

[0009] Step 2: Dissolve NaCl and MCl dichloride in ultrapure water and stir until homogeneous to obtain material B; add material A to material B and stir at room temperature to obtain material C through a spontaneous metal corrosion process;

[0010] Step 3: Wash material C sequentially with ultrapure water and anhydrous ethanol, then dry the washed material C in an oven to obtain material D. Finally, place material D in a tube furnace and calcine it under inert gas protection to obtain the target product.

[0011] Further preferably, in step 1, the concentration of the dilute hydrochloric acid is 0.1–1 mol / L.

[0012] Further preferred, in step 2, the molar ratio of NaCl and MCl constituting the dichloride is 0.5:0.1 to 0.5, where M is Mn, Ni, Zn or Co.

[0013] In a further preferred embodiment, in step 2, the stirring time at room temperature is 12–16 hours.

[0014] Further preferred, in step 3, the calcination conditions are as follows: first, the temperature is raised to 200-500°C at a heating rate of 2-3°C / min, held for 1-2 hours, and then naturally cooled to room temperature.

[0015] Further preferably, in step 3, the inert gas is at least one of argon and nitrogen.

[0016] Further preferably, in steps 1 and 3, the drying is carried out at 60–80°C for 6–10 hours.

[0017] The present invention further provides the application of the Fe-based bifunctional monolithic catalyst prepared according to the above preparation method in the treatment of organic wastewater. Specifically, in the presence of the Fe-based bifunctional monolithic catalyst, wastewater containing organic pollutants is contacted with an oxidant and reacted to obtain purified water after the reaction.

[0018] Further preferably, in the above-mentioned organic wastewater treatment method, the oxidant is at least one of potassium periodate, sodium persulfate, hydrogen peroxide, and sodium sulfite, with potassium periodate being preferred.

[0019] In a further preferred embodiment, in the above-mentioned organic wastewater treatment method, the organic pollutant is at least one of Golden Orange II, Neutral Red, Congo Red, Methyl Violet, etc.

[0020] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0021] (1) This invention utilizes a two-step method of dichlorination-heat treatment to prepare Fe-based bifunctional monolithic catalysts, because Cl - Ions possess strong penetrating power and depassivation properties, transforming metallic iron foam into bimetallic (Fe and M) hydroxides. Further heat treatment converts these bimetallic hydroxides into bimetallic oxides. The greatest advantage of this process is that the active material can grow in situ on the substrate surface, effectively preventing its detachment and significantly improving catalyst stability. Simultaneously, using low-cost transition metals as raw materials, the iron foam not only serves as a support material but also provides an Fe source for the catalyst, thus avoiding the need for additional Fe sources and reducing production costs.

[0022] (2) This invention ingeniously utilizes the harmful phenomenon of iron corrosion to prepare a highly efficient catalytic material, achieving the goal of "turning waste into treasure". The preparation method is innovative and simple to operate. The prepared Fe-based bifunctional monolithic catalyst can be activated by the activator potassium periodate using highly active sites, and achieves efficient removal of pollutants from organic wastewater based on the catalytic degradation method of non-free radical reaction that generates electron transfer.

[0023] (3) The preparation process of the Fe-based bifunctional monolithic catalyst of this invention is simple, energy-saving, and time-saving, which can significantly reduce the preparation cost, making it particularly suitable for the field of wastewater treatment. Furthermore, compared with traditional powder catalysts, this invention avoids problems such as difficult recovery, low catalyst utilization, and excessive precipitation during the reaction process, thus improving the overall efficiency and economy of the catalyst. Moreover, this catalyst is non-toxic, harmless, and environmentally friendly, possessing significant ecological and environmental protection value, especially in my country's water treatment field, where it has broad application prospects and plays a positive role in promoting the advancement of ecological and environmental protection technologies.

[0024] (4) The foamed iron-supported bimetallic catalyst prepared in this invention can rapidly activate periodate to generate active free radicals and efficiently degrade organic pollutants. The foamed iron-supported bimetallic catalyst has a stable three-dimensional macroporous structure and abundant interfacial sites. At the same time, there is efficient mass transfer, enhanced electron transfer capacity and strong synergistic effect between the iron and metal M in the material. This unique morphology and synergistic effect ensure that it has excellent activity and durability in degrading various organic pollutants. Attached Figure Description

[0025] Figure 1 This is a SEM image of the precursor material C obtained in step 2 of Example 1;

[0026] Figure 2 SEM image of the MnFe-IF-300 catalyst prepared in Example 1;

[0027] Figure 3 TEM of the MnFe-IF-300 catalyst prepared in Example 1 Figure 3 (a) and HRTEM Figure 3 (b) in the middle;

[0028] Figure 4 The elemental mapping diagram of the MnFe-IF-300 catalyst prepared in Example 1;

[0029] Figure 5 In the figure, (a) is the XRD pattern of MnFe-IF catalyst samples obtained at different calcination temperatures, and (b) is the XRD pattern of MFe-IF catalyst samples obtained by corrosion of foamed iron by different metals.

[0030] Figure 6The degradation diagrams of different organic pollutants by the MnFe-IF-300 catalyst prepared in Example 1 are shown.

[0031] Figure 7 The degradation of Golden Orange II by the MnFe-IF-300 catalyst prepared in Example 1 under different oxidants is shown in the figure.

[0032] Figure 8 Degradation of Golden Orange II by Fe-based bifunctional monolithic catalysts prepared at different calcination temperatures;

[0033] Figure 9 The degradation diagram of Golden Orange II by Fe-based bifunctional monolithic catalysts prepared with different metals is shown.

[0034] Figure 10 The diagram shows the repeatability of the degradation of Orange II by the MnFe-IF-300 catalyst prepared in Example 1.

[0035] Figure 11 XPS spectra of the MnFe-IF-300 catalyst before and after the first reaction, and the Fe-IF catalyst as a comparison.

[0036] Figure 12 The degradation of Orange II by the MnFe-IF-300 catalyst prepared in Example 1 under different pH conditions is shown in the figure.

[0037] Figure 13 The degradation diagram of Golden Orange II by the MnFe-IF-300 catalyst prepared in Example 1 under the presence of different anions is shown.

[0038] Figure 14 The degradation of Orange II by the MnFe-IF-300 catalyst prepared in Example 1 under different water qualities is shown in the figure. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments. The preferred embodiments described herein are only used to illustrate and explain the present invention.

[0040] I. Preparation of Fe-based bifunctional monolithic catalysts

[0041] Example 1

[0042] In this embodiment, the Fe-based bifunctional monolithic catalyst was prepared according to the following steps:

[0043] Step 1: Cut a piece of paper with a size of 2*2cm. 2The foamed iron was immersed in 0.1 mol / L dilute hydrochloric acid and ultrasonically cleaned for 15 min to remove oxides on the surface of the foamed iron. Then it was rinsed with ultrapure water to remove residual dilute hydrochloric acid. The foamed iron was then immersed in anhydrous ethanol and ultrasonically cleaned for 15 min to remove organic contaminants on the surface of the foamed iron. After ultrasonic cleaning, it was rinsed with anhydrous ethanol again. Finally, it was dried in a vacuum oven at 60°C for 6 h to obtain material A.

[0044] Step 2: Dissolve NaCl and MnCl2·4H2O in 100 mL of ultrapure water and stir until homogeneous to obtain material B, wherein the concentrations of NaCl and MnCl are both 0.5 mol / L. Add material A to material B and stir at room temperature for 14 h to obtain material C through a spontaneous metal corrosion process.

[0045] Step 3: Wash material C sequentially with ultrapure water and anhydrous ethanol, then dry the washed material C in a vacuum oven at 60°C for 6 hours to obtain material D. Place material D into a quartz boat, then place the quartz boat into a tube furnace and calcine at 300°C for 60 minutes (under nitrogen protection, heating rate 2°C / min). After cooling to room temperature, the Fe-based bifunctional monolithic catalyst, denoted as MnFe-IF-300, is obtained.

[0046] Example 2

[0047] In this embodiment, the Fe-based bifunctional monolithic catalyst was prepared using the same method as in Example 1, except that the calcination temperature in step 3 was adjusted to 200℃ or 400℃, and the resulting samples were denoted as MnFe-IF-200 and MnFe-IF-400, respectively.

[0048] Example 3

[0049] In this embodiment, Fe-based bifunctional monolithic catalysts were prepared using the same method as in Example 1, with the only difference being that MnCl2·4H2O was replaced with equimolar concentrations of ZnCl2, CoCl2·6H2O, and NiCl2·6H2O. The resulting samples were denoted as ZnFe-IF-300, CoFe-IF-300, and NiFe-IF-300, respectively.

[0050] Comparative Example 1

[0051] In this embodiment, the Fe-based bifunctional monolithic catalyst was prepared using the same method as in Example 1, except that the amount of MnCl2·4H2O added in step 2 was 0.

[0052] II. Characterization of Fe-based bifunctional monolithic catalysts

[0053] 1. Characterization

[0054] Figure 1The image shows an SEM image of the precursor material C obtained in step 2 of Example 1. It can be seen from the image that the foamed iron after double salt etching is covered with uniform nanoparticles and has a fluffy and porous structure. Figure 2 The image shows a SEM image of the MnFe-IF-300 catalyst prepared in Example 1. It can be seen from the image that after high-temperature calcination, the metal particles on the foamed iron substrate become finer and denser. Figure 3 TEM of the MnFe-IF-300 catalyst prepared in Example 1 Figure 3 (a) and HRTEM Figure 3 As shown in (b) of the figure, the sample surface is loaded with Fe2O3 nanoparticles after high-temperature calcination. Figure 4 The image shows the elemental mapping of the MnFe-IF-300 catalyst prepared in Example 1. It can be seen from the image that Mn, Fe, and O are uniformly distributed on the foamed iron. Figure 5 Figure (a) shows the XRD patterns of MnFe-IF catalyst samples obtained at different calcination temperatures. The figure shows a strong peak at 44.67° and 65.1° on the calcined Fe-based bifunctional monolithic catalyst, typical characteristic peaks of iron generated on the iron foam substrate. A peak is observed on the Fe2O3(311) surface at 43.4°, caused by oxidation of the foamed iron during calcination. Notably, no manganese was detected in the Fe-based bifunctional monolithic catalyst, likely due to the high dispersion of MnOx on the catalyst. Figure 5 (b) shows the XRD patterns of MFe-IF catalyst samples obtained by corrosion of foamed iron with different metals, all of which show strong synthetic iron peaks.

[0055] 2. Characterization of degradation performance for organic pollutants

[0056] (1) Prepare a 20 mg / L solution of Orange II (or Neutral Red, Congo Red, Methyl Violet) to simulate organic pollutants (V = 200 mL), and add 0.1 g / L potassium periodate PI (or sodium persulfate PDS, hydrogen peroxide and sodium sulfite) and one MnFe-IF-300 catalyst prepared in Example 1. React at 25 °C for 25 min. Take samples at different reaction times, measure the concentration of pollutants using a UV spectrophotometer and calculate the removal rate of toxic organic pollutants.

[0057] Figure 6 The graph shows the degradation of different organic pollutants by the MnFe-IF-300 catalyst. When PI is used as the oxidant, the degradation rates of Orange II, Neutral Red, Congo Red and Methyl Violet are 96.2%, 85.4%, 86.9% and 89.8%, respectively. This proves that the Fe-based bifunctional monolithic catalyst has a good removal rate for different organic pollutants. Figure 7The graph shows the degradation of Orange II by MnFe-IF-300 catalyst under different oxidants. The degradation performance of Orange II in PDS, Na2SO3 and H2O2 systems is 89.5%, 50.1% and 40.4%, respectively. Figure 8 The graph shows the degradation of Orange II by MnFe-IF monolithic catalysts prepared at different calcination temperatures. Figure 9 The degradation diagram of Golden Orange II is shown by Fe-based bifunctional monolithic catalysts prepared with different metals.

[0058] (2) Stability testing of Fe-based bifunctional monolithic catalyst

[0059] A 20 mg / L solution of Orange II was prepared to simulate organic pollutants (V = 200 mL). Simultaneously, 0.1 g / L potassium periodate and one tablet of the MnFe-IF-300 catalyst prepared in Example 1 were added. The reaction was carried out at 25 °C for 25 min. Samples were taken at different reaction times, and the concentration of pollutants was measured using a UV spectrophotometer to calculate the removal rate of toxic organic pollutants. After each test, the MnFe-IF-300 catalyst was removed, rinsed with deionized water and anhydrous ethanol, dried, and then subjected to degradation experiments again using the same method to test its repeatability.

[0060] Figure 10 The figure shows the repeatability of the MnFe-IF-300 catalyst for the degradation of Orange II. As can be seen from the figure, the prepared material still exhibits good degradation performance after four repeated cycles, which proves that the Fe-based bifunctional monolithic catalyst has stable catalytic activity in the Fe-based bifunctional monolithic catalyst / potassium periodate system. This indicates that the Fe-based bifunctional monolithic catalyst has good reusability in the degradation of Orange II. Figure 11 The XPS spectra of MnFe-IF-300 and Fe-IF-300 before and after the first reaction are shown. The XPS spectra show the presence of Mn, Fe and O elements, with peaks at 528–533, 640–655 and 708–727 eV belonging to O 1s, Mn 2p and Fe 2p, respectively.

[0061] (3) Effects of different pH environments on catalyst performance

[0062] A 20 mg / L solution of Orange II was prepared to simulate organic pollutants (V = 200 mL). The pH of the pollutants was 3.01–7.96. 0.1 g / L potassium periodate PI and one tablet of the MnFe-IF-300 catalyst prepared in Example 1 were added. The reaction was carried out at 25 °C for 25 min. Samples were taken at different reaction times, and the concentration of pollutants was measured using a UV spectrophotometer to calculate the removal rate of toxic organic pollutants.

[0063] Figure 12The graph shows the degradation of Orange II by the MnFe-IF-300 catalyst under different pH conditions. It can be seen from the graph that the Fe-based bifunctional monolithic catalyst can exhibit good catalytic performance over a wide pH range.

[0064] (4) Effects of different anions on catalyst performance

[0065] Prepare a 20 mg / L solution of Orange II to simulate organic pollutants (V = 200 mL), and add 0.5 mM Cl. - NO3 - SO4 2- HCO3 - Simultaneously, 0.1 g / L potassium periodate PI and one piece of MnFe-IF-300 catalyst prepared in Example 1 above were added, and the reaction was carried out at 25°C for 25 min. Samples were taken at different reaction times, and the concentration of pollutants was measured using an ultraviolet spectrophotometer to calculate the removal rate of toxic organic pollutants.

[0066] Figure 13 The graph shows the degradation of Orange II by the MnFe-IF-300 catalyst under different anions. It can be seen from the graph that the catalytic performance of the Fe-based bifunctional monolithic catalyst is not significantly affected by different anions, and it still has a good degradation effect on Orange II.

[0067] (5) The effect of different water qualities on catalyst performance

[0068] 20 mg / L Orange II solutions were prepared using deionized water, pond water, and river water to simulate organic pollutants (V = 200 mL). 0.1 g / L potassium periodate PI and one MnFe-IF-300 catalyst prepared in Example 1 were added. The mixture was reacted at 25 °C for 25 min. Samples were taken at different reaction times, and the concentration of pollutants was measured using a UV spectrophotometer to calculate the removal rate of toxic organic pollutants.

[0069] Figure 14 The graph shows the degradation of Orange II by the MnFe-IF-300 catalyst under different water qualities. As can be seen from the graph, the Fe-based bifunctional monolithic catalyst has a good degradation effect on Orange II in different actual water bodies. This proves that the Fe-based bifunctional monolithic catalyst has strong anti-interference performance when exerting its catalytic effect, and has great practical application value.

[0070] The above are merely exemplary embodiments of the present invention and are 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 protection scope of the present invention.

Claims

1. The application of an Fe-based bifunctional monolithic catalyst in the treatment of organic wastewater, characterized in that, In the presence of an Fe-based bifunctional monolithic catalyst, wastewater containing organic pollutants is contacted with and reacted with the oxidant potassium periodate to obtain purified water. The Fe-based bifunctional monolithic catalyst is prepared according to the following steps: Step 1: Wash the foamed iron sequentially with dilute hydrochloric acid, ultrapure water and anhydrous ethanol, and finally dry it in an oven to obtain material A; Step 2: Dissolve NaCl and MCl dichloride in ultrapure water and stir until homogeneous to obtain material B; add material A to material B and stir at room temperature to obtain material C through a spontaneous metal corrosion process; the molar ratio of NaCl and MCl constituting the dichloride is 0.5:0.1~0.5, where M is Mn, Ni, Zn or Co; Step 3: Wash material C sequentially with ultrapure water and anhydrous ethanol, then dry the washed material C in an oven to obtain material D; finally, place material D in a tube furnace and calcine it under inert gas protection to obtain the target product; the calcination conditions are as follows: first, heat to 200~500℃ at a heating rate of 2~3℃ / min, hold for 1~2 h, and then cool naturally to room temperature.

2. The application according to claim 1, characterized in that: In step 1, the concentration of the dilute hydrochloric acid is 0.1~1 mol / L.

3. The application according to claim 1, characterized in that: In step 2, the stirring time at room temperature is 12-16 h.

4. The application according to claim 1, characterized in that: In steps 1 and 3, the drying process is carried out at 60-80°C for 6-10 hours.

5. The application according to claim 1, characterized in that: The organic pollutant is at least one of Golden Orange II, Neutral Red, Congo Red, and Methyl Violet.

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