Fe3n@C fenton catalyst prepared from red mud and application thereof

Abstract

The present application relates to the technical field of catalysts for water treatment, and specifically discloses a Fe3N@C Fenton catalyst prepared from red mud, and also relates to the application thereof. The Fe3N@C Fenton catalyst prepared from red mud provided by the present application introduces abundant hydroxyl groups on the surface of the red mud through liquid-phase plasma discharge, strengthens the interfacial interaction between the red mud and nitrogen-containing organic molecules, and forms an envelope structure. Then, high-temperature calcination is used to pyrolyze the nitrogen-containing intermediate product and chemically react with the iron element in the red mud to form an iron-nitrogen compound catalyst, i.e. the Fe3N@C Fenton catalyst. The Fenton-like catalyst provided by the present application can realize efficient Fenton-like oxidation removal of refractory organic matter in the presence of oxidizing agents such as hydrogen peroxide and persulfate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts for water treatment, in particular to a Fe3N@C Fenton-like catalyst prepared from red mud, and also relates to the application thereof. BACKGROUND

[0002] The intensification of human activities has led to a large amount of wastewater containing organic pollutants being discharged into the natural environment, which has brought serious threats to ecological environment safety and human health. Advanced oxidation is an effective method for degrading organic pollutants in water to achieve detoxification. Fenton-like oxidation has attracted increasing attention due to its wide applicable pH range and avoidance of the formation of a large amount of iron sludge caused by traditional homogeneous Fenton oxidation.

[0003] The key to Fenton-like catalytic oxidation lies in the development of efficient heterogeneous Fenton-like catalysts. In recent years, various types of Fenton-like catalysts based on transition metals such as iron, cobalt, and nickel have been developed, and effective removal of refractory pollutants in water has been achieved. However, the high application cost is still an important factor restricting the popularization and application of this technology. Therefore, it is very important to develop catalysts with a wide range of raw materials and low prices for the development of Fenton-like oxidation technology. Red mud is a solid waste generated during the industrial production of alumina by the Bayer process. It poses a challenging environmental problem due to its large production and difficulty in disposal. In fact, red mud is composed of Al, Fe, Si, and other elements, which are exactly the chemical substances commonly used in the development of Fenton-like catalysts. Therefore, using red mud waste as a carrier and even a precursor for Fenton-like catalysts not only provides an ideal raw material for developing low-cost heterogeneous catalysts and achieving "waste treatment with waste", but also provides a new path for the resource utilization of red mud waste.

[0004] Due to the inert surface of raw red mud, most of the current studies have adopted a method of thermochemical modification to prepare red mud-based Fenton-like catalysts. For example, carbon-containing precursors are used to reduce magnetite, zero-valent iron, and iron carbide in red mud at high temperatures during carbonization and pyrolysis. However, the zero-valent iron obtained by carbon thermal reduction usually has poor stability and is prone to passivation on the surface. Moreover, the activity of iron-based oxides and carbides in Fenton-like reactions is still limited.

[0005] Based on the above problems, the present application aims to develop a new red mud-based Fenton-like catalyst with high activity and excellent performance. SUMMARY

[0006] The technical problem solved by the present application is to provide a Fe3N@C Fenton-like catalyst prepared from red mud, and the application of the prepared Fenton-like catalyst.

[0007] To solve the above technical problems, the technical scheme adopted by the present application is: a Fe3N@C Fenton catalyst prepared from red mud, which is prepared by a method comprising the following steps:

[0008] S1: dispersing raw red mud in water to prepare a red mud suspension, and adjusting the pH value of the red mud suspension to 5.0-10.0;

[0009] S2: placing the red mud suspension with a pH value of 5.0-10.0 obtained in step S1 in a plasma discharge reactor, and performing discharge activation treatment on the red mud, then performing solid-liquid separation, and drying the obtained solid to obtain plasma-activated red mud;

[0010] S3: mixing the plasma-activated red mud with a nitrogen-containing organic substance to prepare a high-temperature calcination precursor;

[0011] S4: performing heat calcination treatment on the high-temperature calcination precursor to prepare the Fe3N@C Fenton catalyst.

[0012] As an embodiment of the present application, the content of red mud in the red mud suspension is 30-80 g / L.

[0013] As an embodiment of the present application, the raw red mud in step S1 is red mud generated in the process of preparing alumina by the Bayer process. The raw red mud can be in powder form or in slurry form containing water. The mass percentage content of iron oxide in the raw red mud is ≥3%.

[0014] As an embodiment of the present application, in step S1, the pH value of the red mud suspension is adjusted by using an acid solution, such as a hydrochloric acid solution, a sulfuric acid solution, a phosphoric acid solution, etc.

[0015] As an embodiment of the present application, the plasma discharge reactor adopts a dielectric barrier discharge mode.

[0016] As an embodiment of the present application, the discharge conditions meet at least one of the following conditions (i)-(iii):

[0017] (i) the discharge voltage is 5-25 KV;

[0018] (ii) the discharge atmosphere is any one of air, oxygen, and argon;

[0019] (iii) the discharge activation treatment time is 2-20 minutes.

[0020] As an embodiment of the present application, the nitrogen-containing organic substance is selected from at least one of melamine, urea, dicyandiamide, and monocyandiamide.

[0021] As an embodiment of the present application, in step S3, the mass ratio of the mixing of the plasma-activated red mud and the nitrogen-containing organic matter is: plasma-activated red mud: nitrogen-containing organic matter = 1: (0.1-2). Specifically, the mass ratio of the mixing of the plasma-activated red mud and the nitrogen-containing organic matter (calculated as plasma-activated red mud: nitrogen-containing organic matter) can be 1:0.1, 1:0.5, 1:0.9, 1:1, 1:1.5, 1:2, or any ratio within the range of 1: (0.1-2).

[0022] As an embodiment of the present application, in step S3, the mixing is performed by a ball milling mixing method.

[0023] As an embodiment of the present application, the ball milling mixing is performed at a ball milling rotation speed of 20-100 rpm for 1-10 h.

[0024] As an embodiment of the present application, in step S4, the heat calcination treatment satisfies at least one of the following conditions ①-③:

[0025] ① The heat calcination treatment is performed in a tube furnace, and the reaction atmosphere is any one of air, argon, oxygen, and nitrogen;

[0026] ② The heat calcination treatment is performed at a treatment temperature of 400-600℃ for 1-4 h;

[0027] ③ The heat calcination treatment is performed at a heating rate of 2-10℃ / min.

[0028] The present application also provides an application of the Fe3N@C Fenton-like catalyst prepared from the red mud in the treatment of organic pollutant wastewater.

[0029] The present application further provides an application of the Fe3N@C Fenton-like catalyst prepared from the red mud in the treatment of printing and dyeing wastewater.

[0030] This invention provides a method for preparing Fe3N@C-type Fenton catalysts from red mud using a method that utilizes high-temperature pyrolysis of nitrogen-containing organic molecules to regulate the transformation of plasma-activated red mud into a Fe3N@C composite structure. First, raw red mud is dispersed in water to form a red mud suspension. Then, active substances such as free radicals, ions, electrons, and reactive oxygen species generated by low-temperature plasma discharge are used to rapidly activate sites on the red mud surface, resulting in plasma-activated red mud. The plasma-activated red mud is then ball-milled and thoroughly mixed with nitrogen-containing organic matter to obtain plasma-activated red mud encapsulated by nitrogen-containing organic matter, which serves as the catalyst preparation precursor. The catalyst preparation precursor is then thermally calcined, and the pyrolysis intermediates react chemically with iron to prepare the Fe3N@C-type Fenton catalyst. During the preparation process, abundant hydroxyl groups are introduced onto the red mud surface through liquid-phase plasma discharge, strengthening the interfacial interaction between the red mud and nitrogen-containing organic molecules to form an encapsulation structure. Subsequently, high-temperature calcination is used to pyrolyze the nitrogen-containing intermediates, which then react chemically with iron in the red mud to form an iron-nitrogen compound catalyst, i.e., the Fe3N@C-type Fenton catalyst.

[0031] The Fe3N@C Fenton-like catalyst prepared from red mud provided by this invention employs a preparation method that, on the one hand, rapidly activates the active sites on the surface of red mud through plasma discharge in the liquid phase, overcoming the limitations of gas-solid mass transfer and the difficulty in large-scale application of traditional gas-phase plasma discharge; on the other hand, the surface hydroxyl groups introduced by the liquid-phase plasma undergo strong interfacial interactions with nitrogen-containing precursors, which is conducive to the formation of iron nitride active components during high-temperature pyrolysis. The nitrogen-doped carbon formed by organic carbonization further enhances the interfacial mass transfer and charge transfer between the iron nitride active centers and pollutant molecules, enabling highly efficient Fenton-like oxidation removal of recalcitrant organic matter in the presence of oxidants such as hydrogen peroxide and persulfate. The preparation method employed in this invention is simple, easy to control, and highly applicable, providing an effective pathway for advanced oxidation degradation of organic pollutants in water, and simultaneously offering a new route for the resource utilization of red mud solid waste.

[0032] The Fe3N@C-type Fenton catalyst prepared from red mud provided by this invention is an iron-based nitride with Fe-NC as the active center. It has stable physicochemical properties and extremely high activity in interfacial reactions such as molecular oxygen activation.

[0033] Compared with the prior art, the Fe3N@C-type Fenton catalyst of the present invention has the following advantages:

[0034] 1. Red mud, as a solid waste generated from large-scale production, is costly to treat and dispose of. Developing it into a catalyst for the efficient removal of pollutants from water has realized the resource utilization of red mud solid waste, resulting in significant environmental benefits.

[0035] 2. The surface of the red mud is activated by liquid plasma, which enhances the interfacial interaction between the red mud and nitrogen-containing organic matter, helps to form iron nitride active components under high-temperature pyrolysis conditions, and the plasma activation process is simple, fast and efficient, without consuming a large amount of strong acid and strong base, and has obvious environmental benefits.

[0036] 3. The carbonized layer further strengthens the charge transfer between the active center and the pollutants, so that the prepared Fe3N@C catalyst has extremely high catalytic activity in the reaction of activating hydrogen peroxide, persulfate and other degradation of organic pollutants.

[0037] 4. The preparation method of the Fenton-like catalyst provided by the application is simple, the raw materials are widely available, the cost is low, and the Fe3N@C catalyst has strong magnetism and is easy to recycle and reuse after use. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is the XRD test result graph of the Fe3N@C Fenton-like catalyst prepared in Example 1 of the application;

[0039] Figure 2 is a comparison graph of pollutant removal rates obtained by experiments using three different catalysts in Application Example 1 of the application;

[0040] Figure 3 is a comparison graph of pollutant removal rates obtained by experiments using four different catalysts in Application Example 2 of the application;

[0041] Figure 4 is a comparison graph of pollutant removal rates obtained by experiments using three different catalysts in Application Example 3 of the application. DETAILED DESCRIPTION

[0042] The technical solutions of the application will be described in detail below through specific examples. The following examples are intended to further illustrate the content of the application, rather than limit the scope of protection of the claims of the application.

[0043] In the following examples and comparative examples, the reagents used are all commercially available products.

[0044] Example 1

[0045] The present embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0046] S1: 5g of original red mud powder (the mass percentage content of iron oxide in the original red mud is about 5%) is dispersed in 100mL of water to prepare a red mud suspension, the content of the red mud in the red mud suspension is 50g / L, and then 100 microliters of 1M hydrochloric acid solution is added to control the pH value of the red mud suspension to 9.0;

[0047] S2: The red mud suspension with pH value of 9.0 obtained in step S1 is placed in a plasma discharge reactor for discharge activation treatment of the red mud, the plasma discharge reactor adopts a dielectric barrier discharge mode, the discharge condition is: a discharge voltage of 10 KV, a discharge atmosphere of air, and a discharge activation treatment time of 5 minutes; after the discharge treatment is completed, the precipitated powder solid is collected, and the separated solid is dried to obtain plasma-activated red mud;

[0048] S3: 5g of the plasma-activated red mud is weighed and mixed with 5g of urea by ball milling to obtain a high-temperature calcined precursor;

[0049] S4: The high-temperature calcined precursor is placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere, the temperature is raised to 550°C at a rate of 5°C / min, and the high-temperature calcination is performed for 2h, and then the temperature is cooled to room temperature to obtain the Fe3N@C Fenton-like catalyst.

[0050] The XRD test results of the Fe3N@C Fenton-like catalyst prepared in this example are shown in Figure 1 Figure 1 The crystal diffraction peaks appearing in the figure correspond to the standard card 72-2125 of Fe3N, and the broad peak at 25 degrees indicates that the carbon in the composite product is amorphous structure.

[0051] Example 2

[0052] This example provides a Fe3N@C Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0053] S1: 5g of raw red mud powder (the mass percentage content of iron oxide in the raw red mud is about 5%) is dispersed in 100mL of water to prepare a red mud suspension, the content of the red mud in the red mud suspension is 50g / L, and then 100 microliters of 1M hydrochloric acid solution is added to adjust the pH value of the red mud suspension to 9.0;

[0054] S2: The red mud suspension with pH value of 9.0 obtained in step S1 is placed in a plasma discharge reactor for discharge activation treatment of the red mud, the plasma discharge reactor adopts a dielectric barrier discharge mode, the discharge condition is: a discharge voltage of 10 KV, a discharge atmosphere of air, and a discharge activation treatment time of 5 minutes; after the discharge treatment is completed, the precipitated powder solid is collected, and the separated solid is dried to obtain plasma-activated red mud;

[0055] ​S3: 5 g of the plasma-activated red mud was weighed out and mixed with 5 g of urea by ball milling at a rotation speed of 50 rpm for 2 h to obtain a high-temperature calcination precursor;

[0056] S4: The high-temperature calcination precursor was placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere, and was heated to 550°C at a heating rate of 5°C / min, and was high-temperature calcined for 2 h, and was then cooled to room temperature to obtain the Fe3N@C Fenton-like catalyst.

[0057] Example 3

[0058] The Fe3N@C Fenton-like catalyst prepared from red mud provided in the embodiment has the following preparation steps:

[0059] S1: 5 g of raw red mud powder (the mass percentage of iron oxide in the raw red mud is about 5%) was dispersed in 100 mL of water to obtain a red mud suspension, and the content of the red mud in the red mud suspension was 50 g / L, and then 100 microliters of 1M hydrochloric acid solution was added to adjust the pH value of the red mud suspension to 9.0;

[0060] S2: The red mud suspension with a pH value of 9.0 obtained in step S1 was placed in a plasma discharge reactor, and the red mud was subjected to discharge activation treatment, the plasma discharge reactor adopted a dielectric barrier discharge mode, the discharge conditions were as follows: a discharge voltage of 10 KV, a discharge atmosphere of oxygen, and a discharge activation treatment time of 5 minutes; after the discharge treatment, the precipitated powder solid was collected, and the separated solid was dried to obtain the plasma-activated red mud;

[0061] S3: 5 g of the plasma-activated red mud was weighed out and mixed with 5 g of urea by ball milling at a rotation speed of 50 rpm for 2 h to obtain a high-temperature calcination precursor;

[0062] S4: The high-temperature calcination precursor was placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere, and was heated to 550°C at a heating rate of 5°C / min, and was high-temperature calcined for 2 h, and was then cooled to room temperature to obtain the Fe3N@C Fenton-like catalyst.

[0063] Example 4

[0064] The Fe3N@C Fenton-like catalyst prepared from red mud provided in the embodiment has the following preparation steps:

[0065] S1: 5 g of raw red mud powder (the mass percentage content of iron oxide in the raw red mud is about 5%) was dispersed in 100 mL of water to prepare a red mud suspension, the content of the red mud in the red mud suspension was 50 g / L, then 100 microliters of 1M hydrochloric acid solution was added to adjust the pH value of the red mud suspension to 9.0;

[0066] S2: The red mud suspension with a pH value of 9.0 obtained by the step S1 was placed in a plasma discharge reactor for discharge activation treatment of the red mud, the plasma discharge reactor adopted a dielectric barrier discharge mode, the discharge conditions were: a discharge voltage of 10KV, a discharge atmosphere of argon, and a discharge activation treatment time of 5 minutes; after the discharge treatment, the precipitated powder solid was collected, and the separated solid was dried to obtain a plasma-activated red mud;

[0067] S3: 5 g of the plasma-activated red mud was mixed with 5 g of urea by ball milling to prepare a high-temperature calcined precursor;

[0068] S4: The high-temperature calcined precursor was placed in a tube furnace for heat calcination treatment under a nitrogen atmosphere, the temperature was raised to 550℃ at a rate of 5℃ / min, and the high-temperature calcination was performed for 2h, then the temperature was cooled to room temperature to prepare a Fe3N@C Fenton-like catalyst.

[0069] Example 5

[0070] The embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0071] S1: 5 g of raw red mud powder (the mass percentage content of iron oxide in the raw red mud is about 5%) was dispersed in 100 mL of water to prepare a red mud suspension, the content of the red mud in the red mud suspension was 50 g / L, then 100 microliters of 1M hydrochloric acid solution was added to adjust the pH value of the red mud suspension to 9.0;

[0072] S2: The red mud suspension with a pH value of 9.0 obtained by the step S1 was placed in a plasma discharge reactor for discharge activation treatment of the red mud, the plasma discharge reactor adopted a dielectric barrier discharge mode, the discharge conditions were: a discharge voltage of 10KV, a discharge atmosphere of argon, and a discharge activation treatment time of 5 minutes; after the discharge treatment, the precipitated powder solid was collected, and the separated solid was dried to obtain a plasma-activated red mud;

[0073] S3: 5 g of the plasma-activated red mud was mixed with 5 g of urea by ball milling to prepare a high-temperature calcined precursor;

[0074] S4: The high-temperature calcination precursor is placed in a tube furnace, and heat calcination treatment is carried out under a nitrogen atmosphere, the temperature is raised to 550 DEG C at a temperature raising rate of 5 DEG C / min, high-temperature calcination is carried out for 2 h, and then the temperature is cooled to room temperature, thereby preparing the Fe3N@C Fenton-like catalyst.

[0075] Example 6

[0076] The embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0077] S1: 5g of original red mud powder (the mass percentage content of iron oxide in the original red mud is about 5%) is dispersed in 100ml of water to prepare a red mud suspension, the content of the red mud in the red mud suspension is 50g / L, and then 100ul of 1M hydrochloric acid solution is added to regulate the pH value of the red mud suspension to 9.0;

[0078] S2: The red mud suspension with the pH value of 9.0 obtained through step S1 is placed in a plasma discharge reactor, and the red mud is subjected to discharge activation treatment, the plasma discharge reactor adopts a dielectric barrier discharge mode, the discharge conditions are as follows: the discharge voltage is 10KV, the discharge atmosphere is argon, and the discharge activation treatment time is 10 minutes; after the discharge treatment is completed, the precipitated powder solid is collected, and the separated solid is dried to obtain the plasma-activated red mud;

[0079] S3: 5g of the plasma-activated red mud is mixed with 5g of urea by using a ball milling mixing method, the ball milling rotation speed is 50rpm, and the ball milling time is 2h, thereby preparing a high-temperature calcination precursor;

[0080] S4: The high-temperature calcination precursor is placed in a tube furnace, and heat calcination treatment is carried out under a nitrogen atmosphere, the temperature is raised to 550 DEG C at a temperature raising rate of 5 DEG C / min, high-temperature calcination is carried out for 2 h, and then the temperature is cooled to room temperature, thereby preparing the Fe3N@C Fenton-like catalyst.

[0081] Example 7

[0082] The embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0083] S1: 5g of original red mud powder (the mass percentage content of iron oxide in the original red mud is about 5%) is dispersed in 100ml of water to prepare a red mud suspension, the content of the red mud in the red mud suspension is 50g / L, and then 100ul of 1M hydrochloric acid solution is added to regulate the pH value of the red mud suspension to 9.0;

[0084] S2: The red mud suspension with a pH value of 9.0 obtained in step S1 is placed in a plasma discharge reactor, and the red mud is subjected to discharge activation treatment. The plasma discharge reactor adopts a dielectric barrier discharge mode, and the discharge conditions are as follows: a discharge voltage of 10 KV, an argon gas discharge atmosphere, and a discharge activation treatment time of 20 minutes. After the discharge treatment is completed, the precipitated powder solid is collected, and the separated solid is dried to obtain plasma-activated red mud;

[0085] S3: 5g of the plasma-activated red mud is weighed out and mixed with 5g of urea by ball milling to obtain a high-temperature calcination precursor.

[0086] S4: The high-temperature calcination precursor is placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere. The temperature is raised to 550°C at a rate of 5°C / min, and high-temperature calcination is performed for 2h. After cooling to room temperature, a Fe3N@C Fenton-like catalyst is prepared.

[0087] Example 8

[0088] The present embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0089] S1: 5g of raw red mud powder (the mass percentage of iron oxide in the raw red mud is about 5%) is dispersed in 100mL of water to prepare a red mud suspension. The content of the red mud in the red mud suspension is 50g / L. Then, 100 microliters of 1M hydrochloric acid solution is added to adjust the pH value of the red mud suspension to 9.0.

[0090] S2: The red mud suspension with a pH value of 9.0 obtained in step S1 is placed in a plasma discharge reactor, and the red mud is subjected to discharge activation treatment. The plasma discharge reactor adopts a dielectric barrier discharge mode, and the discharge conditions are as follows: a discharge voltage of 10 KV, an argon gas discharge atmosphere, and a discharge activation treatment time of 20 minutes. After the discharge treatment is completed, the precipitated powder solid is collected, and the separated solid is dried to obtain plasma-activated red mud;

[0091] S3: 5g of the plasma-activated red mud is weighed out and mixed with 5g of urea by ball milling to obtain a high-temperature calcination precursor.

[0092] S4: The high-temperature calcination precursor is placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere. The temperature is raised to 550°C at a rate of 5°C / min, and high-temperature calcination is performed for 2h. After cooling to room temperature, a Fe3N@C Fenton-like catalyst is prepared.

[0093] Example 9

[0094] The embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and preparation steps are as follows:

[0095] S1: 5g of original red mud powder (the mass percentage content of iron oxide in the original red mud is about 5%) is dispersed in 100ml of water to prepare a red mud suspension, the content of the red mud in the red mud suspension is 50g / L, then 100ul of 1M hydrochloric acid solution is added to regulate the pH value of the red mud suspension to 9.0;

[0096] S2: the red mud suspension with the pH value of 9.0 obtained through step S1 is placed in a plasma discharge reactor, and the red mud is subjected to discharge activation treatment, the plasma discharge reactor adopts a dielectric barrier discharge mode, the discharge condition is that the discharge voltage is 10KV, the discharge atmosphere is argon, and the discharge activation treatment time is 5 minutes; after the discharge treatment is completed, the precipitated powder solid is collected, the separated solid is dried, and the plasma-activated red mud is obtained;

[0097] S3: 5g of the plasma-activated red mud is mixed with 5g of monocyanoamine by using a ball milling mixing method, the ball milling rotation speed is 50rpm, and the ball milling time is 2h, so that a high-temperature calcined precursor is prepared;

[0098] S4: the high-temperature calcined precursor is placed in a tube furnace, and is subjected to heat calcination treatment under a nitrogen atmosphere, the temperature is raised to 550 DEG C at a temperature raising rate of 5 DEG C / min, the high-temperature calcination is performed for 2h, and then the temperature is cooled to room temperature, so that the Fe3N@C Fenton-like catalyst is prepared.

[0099] Example 10

[0100] The embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and preparation steps are as follows:

[0101] S1: 5g of original red mud powder (the mass percentage content of iron oxide in the original red mud is about 5%) is dispersed in 100ml of water to prepare a red mud suspension, the content of the red mud in the red mud suspension is 50g / L, then 100ul of 1M hydrochloric acid solution is added to regulate the pH value of the red mud suspension to 9.0;

[0102] S2: the red mud suspension with the pH value of 9.0 obtained through step S1 is placed in a plasma discharge reactor, and the red mud is subjected to discharge activation treatment, the plasma discharge reactor adopts a dielectric barrier discharge mode, the discharge condition is that the discharge voltage is 10KV, the discharge atmosphere is argon, and the discharge activation treatment time is 5 minutes; after the discharge treatment is completed, the precipitated powder solid is collected, the separated solid is dried, and the plasma-activated red mud is obtained;

[0103] S3: 5 g of the plasma-activated red mud was weighed out and mixed with 5 g of urea by ball milling at a rotation speed of 50 rpm for 2 h to obtain a high-temperature calcination precursor;

[0104] S4: The high-temperature calcination precursor was placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere, and was heated to 450°C at a heating rate of 5°C / min, and was high-temperature calcined for 2 h, and was then cooled to room temperature to obtain the Fe3N@C Fenton-like catalyst.

[0105] Example 11

[0106] The present embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0107] S1: 5 g of raw red mud powder (the mass percentage of iron oxide in the raw red mud is about 5%) was dispersed in 100 mL of water to obtain a red mud suspension, and the content of the red mud in the red mud suspension was 50 g / L, and then 100 microliters of 1M hydrochloric acid solution was added to adjust the pH value of the red mud suspension to 9.0;

[0108] S2: The red mud suspension with a pH value of 9.0 obtained in step S1 was placed in a plasma discharge reactor, and the red mud was subjected to discharge activation treatment, the plasma discharge reactor adopted a dielectric barrier discharge mode, the discharge conditions were as follows: a discharge voltage of 10 KV, a discharge atmosphere of argon, and a discharge activation treatment time of 5 minutes; after the discharge treatment, the precipitated powder solid was collected, and the separated solid was dried to obtain the plasma-activated red mud;

[0109] S3: 5 g of the plasma-activated red mud was weighed out and mixed with 5 g of urea by ball milling at a rotation speed of 50 rpm for 2 h to obtain a high-temperature calcination precursor;

[0110] S4: The high-temperature calcination precursor was placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere, and was heated to 450°C at a heating rate of 5°C / min, and was high-temperature calcined for 2 h, and was then cooled to room temperature to obtain the Fe3N@C Fenton-like catalyst.

[0111] Example 12

[0112] The present embodiment provides a Fe3N@C Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0113] S1: 5 g of raw red mud powder (the mass percentage content of iron oxide in the raw red mud is about 5%) was dispersed in 100 mL of water to prepare a red mud suspension, and the content of the red mud in the red mud suspension was 50 g / L, then 100 microliters of 1M hydrochloric acid solution was added to adjust the pH value of the red mud suspension to 9.0;

[0114] S2: The red mud suspension with a pH value of 9.0 obtained in step S1 was placed in a plasma discharge reactor for discharge activation treatment of the red mud. The plasma discharge reactor used a dielectric barrier discharge method, and the discharge conditions were: a discharge voltage of 10KV, a discharge atmosphere of argon, and a discharge activation treatment time of 5 minutes. After the discharge treatment, the precipitated powder solids were collected, and the separated solids were dried to obtain plasma-activated red mud.

[0115] S3: 5 g of the plasma-activated red mud was mixed with 10 g of urea by ball milling to prepare a high-temperature calcined precursor.

[0116] S4: The high-temperature calcined precursor was placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere, with a heating rate of 5℃ / min to 550℃, and high-temperature calcination for 2h, and then cooled to room temperature to prepare a Fe3N@C Fenton-like catalyst.

[0117] Comparative Example 1

[0118] This example provides a catalyst prepared from red mud, and the preparation steps are as follows:

[0119] S1: 5 g of raw red mud powder (the mass percentage content of iron oxide in the raw red mud is about 5%) was mixed with 5 g of urea by ball milling to prepare a catalyst precursor.

[0120] S2: The obtained catalyst precursor was placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere, with a heating rate of 5℃ / min to 550℃, and high-temperature calcination for 2h, and then cooled to room temperature to prepare a catalyst.

[0121] Comparative Example 2

[0122] This example provides a Fenton-like catalyst prepared from red mud, and the preparation steps are as follows:

[0123] S1: 5 g of raw red mud powder (the mass percentage of iron oxide in the raw red mud is about 5%) was dispersed in 100 mL of water to prepare a red mud suspension, and the content of the red mud in the red mud suspension was 50 g / L, and then 100 microliters of 1M hydrochloric acid solution was added to adjust the pH value of the red mud suspension to 9.0;

[0124] S2: The red mud suspension with a pH value of 9.0 obtained by the treatment in step S1 was placed in a plasma discharge reactor for discharge activation treatment of the red mud. The plasma discharge reactor adopts a dielectric barrier discharge mode, and the discharge conditions are as follows: a discharge voltage of 10KV, a discharge atmosphere of argon, and a discharge activation treatment time of 5 minutes. After the discharge treatment, the precipitated powder solids were collected, and the separated solids were dried to obtain plasma-activated red mud.

[0125] S3: 5 g of the plasma-activated red mud was mixed with 5 g of glucose by ball milling to prepare a high-temperature calcined precursor.

[0126] S4: The high-temperature calcined precursor was placed in a tube furnace and subjected to heat calcination treatment under a nitrogen atmosphere. The temperature was raised to 550°C at a rate of 5°C / min, and the high-temperature calcination was performed for 2h, and then the temperature was cooled to room temperature to prepare a Fenton-like catalyst.

[0127] The catalysts prepared in the above examples and comparative examples were subjected to organic pollutant degradation experiments, as follows.

[0128] Application Example 1

[0129] In this application example, methylene blue dye solution was used for experiments, and the concentration of methylene blue was 100 mg / L.

[0130] The raw red mud powder in Example 4, the plasma-activated red mud obtained by the treatment in step S2 in Example 4, and the Fe3N@C Fenton-like catalyst prepared in Example 4 were respectively taken as catalysts for experiments.

[0131] The experimental process is as follows: one of the above catalysts was added to 50 mL of methylene blue dye solution, and the addition amount of the catalyst was 0.5 g / L; 0.5M hydrochloric acid was used to adjust the pH value of the solution system to 3.0, and after reaching the adsorption-desorption equilibrium, 0.01M hydrogen peroxide was added to start the Fenton reaction; after a certain time interval, the reaction solution was taken, filtered with a 0.45 micron microfiltration membrane to prepare a sample solution, and then tested, the concentration of the residual dye in the sample solution was determined by spectrophotometry, and the removal rate of the pollutant was calculated.

[0132] The pollutant removal rate comparison chart obtained by experiments using the above three catalysts is shown in Figure 2 As shown in the figure.

[0133] From Figure 2 It can be seen that the original red mud and the plasma-activated red mud do not show catalytic activity in the reaction of catalyzing hydrogen peroxide to degrade organic dyes, while the Fe3N@C Fenton-like catalyst prepared in Example 4 can completely remove 100 mg / L of methylene blue pollutants in water.

[0134] Application Example 2

[0135] In this application example, methylene blue dye solution is used for experiments, and the concentration of methylene blue is 100 mg / L.

[0136] The Fe3N@C Fenton-like catalysts prepared in Examples 1-4 are respectively taken as catalysts for experiments.

[0137] The experimental process is as follows: one of the above catalysts is added to 50 mL of methylene blue dye solution, and the catalyst dosage is 0.5 g / L; 0.5M hydrochloric acid is used to adjust the pH value of the solution system to 3.0, and after adsorption-desorption equilibrium is reached, 0.01M hydrogen peroxide is added to start the Fenton reaction; after a certain time interval, the reaction solution is taken, filtered with a 0.45 micron microfiltration membrane to prepare a sample solution, and then tested, the concentration of residual dye in the sample solution is determined by spectrophotometry, and the removal rate of pollutants is calculated.

[0138] The pollutant removal rate comparison chart obtained by experiments using the above four catalysts is shown in Figure 3 As shown in the figure.

[0139] From Figure 3 It can be seen that when the red mud is discharged and activated in the plasma discharge reactor, the discharge atmosphere is argon (Example 4), air (Example 1) and oxygen (Example 3), which can effectively activate the surface of the red mud, and the prepared Fe3N@C Fenton-like catalyst can completely remove 100 mg / L of methylene blue pollutants in water. When the discharge atmosphere is nitrogen (Example 2), the active species generated by the plasma has less effect on the surface of the red mud, and the prepared catalyst has no obvious catalytic activity in the reaction of activating hydrogen peroxide. This confirms that under suitable discharge atmosphere conditions, the active species generated by plasma discharge is extremely important for the surface activation of red mud.

[0140] Application Example 3

[0141] In this application example, methylene blue dye solution is used for experiments, and the concentration of methylene blue is 100 mg / L.

[0142] The Fe3N@C Fenton-like catalyst prepared in Example 4, the catalyst prepared in Comparative Example 1 and the catalyst prepared in Comparative Example 2 were respectively taken as the catalyst for experiments.

[0143] The experimental process is as follows: one of the above catalysts was added to 50 mL of methylene blue dye solution, and the catalyst was added in an amount of 0.5 g / L; 0.5 M hydrochloric acid was used to adjust the pH value of the solution system to 3.0, and after reaching adsorption-desorption equilibrium, 0.01 M hydrogen peroxide was added to start the Fenton-like reaction; after a certain time interval, the reaction solution was taken, filtered with a 0.45 micron microfiltration membrane to prepare a sample solution, and then tested, the concentration of the residual dye in the sample solution was determined by spectrophotometry, and the removal rate of the pollutants was calculated.

[0144] The comparison chart of the pollutant removal rates obtained by using the above three catalysts is shown in FIG. 2. Figure 4

[0145] It can be seen from FIG. 2 that the catalyst prepared in Comparative Example 1 (corresponding to Fe3N@C (red mud) in Table 1) does not exhibit catalytic activity in the reaction of activating hydrogen peroxide to degrade organic pollutants. Figure 4 The Fe3N@C Fenton-like catalyst prepared by plasma-activating red mud and urea (i.e., the catalyst prepared in Example 4, corresponding to Fe3N@C (urea) in Table 1) has better catalytic activity in the Fenton-like reaction than the catalyst prepared by plasma-activating red mud and glucose (i.e., the catalyst prepared in Comparative Example 2, corresponding to Fe3N@C (glucose) in Table 1), which indicates that the components of the generated Fe3N are also crucial for improving the Fenton-like activity. Figure 4 Figure 4 Figure 4

[0146] The above description is only an example of the present application, and does not limit the patent scope of the present application, and any equivalent transformation or direct or indirect application in other related technical fields using the content of the present application is included in the patent protection scope of the present application.​​​​

Claims

1. A Fe3N@C Fenton-like catalyst prepared from red mud, characterized in that, The Fe3N@C Fenton-like catalyst is prepared by a method comprising the following steps: S1: dispersing raw red mud in water to prepare a red mud suspension, and adjusting the pH value of the red mud suspension to 5.0-10.0; S2: placing the red mud suspension with a pH value of 5.0-10.0 obtained in step S1 in a plasma discharge reactor, and performing discharge activation treatment on the red mud, then performing solid-liquid separation, and drying the obtained solid to obtain plasma-activated red mud; S3: mixing the plasma-activated red mud with a nitrogen-containing organic matter to prepare a high-temperature calcination precursor; S4: performing heat calcination treatment on the high-temperature calcination precursor to prepare the Fe3N@C Fenton-like catalyst.

2. The Fenton-like catalyst according to claim 1, characterized in that, The content of the red mud in the red mud suspension is 30-80 g / L.

3. The Fenton-like catalyst according to claim 1, characterized in that, The plasma discharge reactor adopts a dielectric barrier discharge mode, and the discharge conditions meet at least one of the following conditions (i)-(iii): (i) the discharge voltage is 5-25 KV; (ii) the discharge atmosphere is any one of air, oxygen, and argon; (iii) the discharge activation treatment time is 2-20 minutes.

4. The Fenton-like catalyst according to claim 1, characterized in that, The nitrogen-containing organic matter is at least one of melamine, urea, dicyandiamide, and monocyandiamide.

5. The Fenton-like catalyst according to claim 1, wherein In step S3, the mass ratio of the plasma-activated red mud to the nitrogen-containing organic matter is 1:(0.1-2).

6. The Fenton-like catalyst according to claim 1, wherein In step S3, the mixing is performed by a ball milling method.

7. The Fenton-like catalyst according to claim 6, characterized in that, The ball milling speed is 20-100 rpm, and the ball milling time is 1-10 h.

8. The Fenton-like catalyst according to claim 1, characterized in that, The heat calcination treatment meets at least one of the following conditions ①-③: ① the heat calcination treatment is performed in a tube furnace, and the reaction atmosphere is any one of air, argon, oxygen, and nitrogen; ② the heat calcination treatment temperature is 400-600℃, and the treatment time is 1-4 h; ③ the heat calcination treatment has a heating rate of 2-10℃ / min.

9. The Fe3N@C Fenton-like catalyst prepared from the red mud according to any one of claims 1-8 is applied to the treatment of organic pollutant wastewater.

10. The Fe3N@C Fenton-like catalyst prepared from the red mud according to any one of claims 1-8 is applied to the treatment of printing and dyeing wastewater.

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