Magnetic composite alumina fenton catalyst, preparation method and application thereof

Abstract

The application provides a magnetic composite alumina Fenton catalyst and a preparation method and application thereof, and belongs to the technical field of environmental functional materials. The magnetic Fe3O4 nanoparticles are prepared by a solvothermal method; then the magnetic Fe3O4 nanoparticles are compounded into alumina small balls by a sol-gel method to prepare a magnetic composite alumina carrier; finally, ferrous ions are introduced into the magnetic composite alumina carrier by an impregnation method, and the target magnetic composite alumina Fenton catalyst is obtained after calcination. The magnetic composite alumina Fenton catalyst prepared by the application has high specific surface area and mechanical strength, excellent magnetic response characteristics and good Fenton catalytic performance, can catalyze the oxidative degradation of methylene blue, and has a good application prospect in the field of organic dye wastewater treatment.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, and particularly relates to a magnetic composite alumina Fenton catalyst, its preparation method and application. Background Technology

[0002] Fe3O4 is an important research direction in magnetic materials. It exhibits superparamagnetism at room temperature, and microspheres can be rapidly separated from the liquid phase using an external magnetic field, enabling reusability. Due to its excellent magnetic responsiveness, biocompatibility, and chemical stability, it has broad application prospects in medicine, pharmacy, catalysis chemistry, separation and purification, and wastewater treatment. Alumina microspheres possess high specific surface area and mechanical strength, low wear rate, good adsorption performance, and thermal stability, making them suitable as catalyst supports. The Fenton oxidation process uses Fe... 2+ Catalytic decomposition of H₂O₂ produces highly oxidizing hydroxyl radicals (·OH), which are then used to oxidize organic matter in wastewater. This method is characterized by its fast reaction rate, simple operation, low energy consumption, and lack of the need for special equipment, making it commonly used for treating organic wastewater. However, its practical application is limited by drawbacks such as a narrow pH range (pH = 3-4), poor stability, insufficient adsorption and catalytic degradation performance, difficulty in recycling, and potential for secondary pollution.

[0003] Patent application number 202011068586.7 discloses a composite fiber membrane loaded with Fe3O4 nanoparticles as a heterogeneous Fenton catalyst and its preparation method. The patent uses ammonia as a precipitant to prepare Fe3O4 nanoparticles by reverse co-precipitation. The casting solution after the nanoparticles are mixed with polyvinylidene fluoride (PVDF) solution is wet-spun to obtain the Fe3O4 / PVDF composite fiber membrane heterogeneous Fenton catalyst. This solves the problem of Fenton catalyst having a narrow pH range (pH=3-4) and being difficult to recycle. However, the catalyst prepared by this patent has insufficient ability to catalyze the degradation of organic dyes. Patent application number 202111582395.7 discloses a heterogeneous Fenton catalyst, its preparation method, and its application. The heterogeneous Fenton catalyst includes a support, an active component, and auxiliary components. The support is alumina microspheres, the active component is Cu, and the auxiliary components are Bi and alkaline earth metals. Modification of the Cu-based catalyst by doping with alkaline earth metals Mg and Bi effectively suppresses the dissolution of metal ions during the heterogeneous Fenton reaction, enhancing the catalyst's stability. However, the heterogeneous Fenton catalyst prepared by this patent suffers from the drawback of being difficult to recycle and prone to causing secondary pollution. Patent application number 202110584813.X discloses a heterogeneous Fenton catalyst with alumina as a support, its preparation method, and its application. This heterogeneous Fenton catalyst consists of an alumina support and CuOx supported on the support, featuring low ion leaching concentration and the ability to be reused multiple times. However, this Fenton catalyst also faces the technical problem of difficult recycling.

[0004] Based on the above, how to introduce magnetic nanomaterials into alumina microspheres to prepare a Fenton catalyst with excellent catalytic stability, adsorption performance, and catalytic degradation performance, while being easy to recycle and free from secondary pollution, is a technical problem that urgently needs to be solved in the field of wastewater treatment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a magnetic composite alumina Fenton catalyst, its preparation method, and its applications.

[0006] This invention employs a sol-gel method to composite magnetic Fe3O4 nanoparticles into alumina microspheres, obtaining a magnetic composite alumina carrier. This magnetic composite alumina carrier is then immersed in an aqueous solution containing ferrous ions. The process involves combining the self-made magnetic composite alumina carrier with Fe... 2+The synergistic effect between them solves the problems of traditional Fenton catalysts being difficult to recycle and having poor adsorption and catalytic degradation performance. It can significantly improve the actual catalytic application effect of magnetic composite alumina Fenton catalysts and greatly expand the application range of Fenton catalysts.

[0007] The first objective of this invention is to provide a method for preparing a magnetic composite alumina Fenton catalyst, comprising the following steps:

[0008] S1. Preparation of magnetic Fe3O4 nanoparticles;

[0009] S2. Preparation of magnetic composite alumina carrier:

[0010] The Fe3O4 nanoparticles described in step S1 are mixed with polyethylene glycol, sodium alginate, boehmite, and deionized water to form a uniform paste. The mixture is then added dropwise to an aqueous solution containing calcium ions. The mixture is then subjected to cross-linking curing, washing with deionized water, and heating and drying to obtain a magnetic composite alumina carrier.

[0011] S3. Preparation of magnetic composite alumina Fenton catalyst:

[0012] The magnetic composite alumina support described in step S2 is immersed in an aqueous solution containing ferrous ions, and then subjected to adsorption, washing with deionized water, heating and drying, and high-temperature calcination in sequence to finally obtain the magnetic composite alumina Fenton catalyst.

[0013] Preferably, the method for preparing the magnetic composite alumina Fenton catalyst is characterized in that the raw material for preparing Fe3O4 nanoparticles in step S1 is ferric chloride, and the solvent is ethylene glycol.

[0014] Preferably, the size of the Fe3O4 nanoparticles in step S1 is 50-200 nm.

[0015] Preferably, in step S2, the Fe3O4 nanoparticles have a mass range of 1.0–25%, polyethylene glycol has a mass range of 1.0–25%, sodium alginate has a mass range of 2.5–25%, and boehmite has a mass range of 25–85%.

[0016] Preferably, the calcium ions in step S2 are one or more of calcium nitrate and calcium chloride, the calcium ion mass concentration is 1.0-30.0 mg / mL, and the cross-linking curing time is 1-12 h.

[0017] Preferably, the size of the magnetic composite alumina carrier in step S2 is 1.0-3.0 mm.

[0018] Preferably, the ferrous ion in step S3 is one or more of ferrous chloride and ferrous sulfate, the ferrous ion mass concentration is 1.0-30 mg / mL, and the adsorption time is 1-12 h.

[0019] Preferably, the calcination temperature in step S3 is 300-600℃ and the time is 3-12h.

[0020] The second objective of this invention is to provide a magnetic composite alumina Fenton catalyst.

[0021] A third objective of this invention is to provide the application of the aforementioned magnetic composite alumina Fenton catalyst in the treatment of organic pollutants in water using hydrogen peroxide solution. The prepared magnetic composite alumina Fenton catalyst is added to a methylene blue solution, adsorbed, and then hydrogen peroxide is added, followed by a Fenton catalytic reaction at room temperature.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention first synthesizes Fe3O4 nanoparticles, introduces the Fe3O4 nanoparticles into alumina microspheres via the sol-gel method, and then loads Fe using an impregnation method. 2+ This endows Fenton catalysts with excellent magnetic response characteristics and catalytic activity, and the operation is simple, the cost is low, and the preparation time is short.

[0024] 2. The magnetic composite alumina Fenton catalyst prepared by this invention not only utilizes the excellent adsorption properties, high mechanical strength, and thermal stability of alumina microspheres, but also leverages the magnetic responsiveness of Fe3O4 nanoparticles and Fe... 2+ Its catalytic properties in the Fenton reaction facilitate the recycling of Fenton catalysts.

[0025] 3. The composite alumina support prepared by this invention can still maintain high magnetic properties after high-temperature calcination. This characteristic not only facilitates the repeated recycling of magnetic composite alumina microspheres, but also improves the utilization rate of catalysts by controlling parameters such as stirring rate and catalytic reaction through magnetic field regulation.

[0026] 4. The magnetic composite alumina Fenton catalyst prepared by this invention integrates physical adsorption, Fenton catalysis and magnetic separation. The preparation method is simple and can be applied to deep wastewater oxidation treatment, especially suitable for catalytic degradation of methylene blue. Attached Figure Description

[0027] Figure 1 This is a SEM image of the magnetic Fe3O4 nanoparticles prepared in Example 1 of this invention;

[0028] Figure 2This is an optical photograph of the magnetic composite alumina carrier prepared in Example 1 of the present invention;

[0029] Figure 3 This is a SEM image of the magnetic composite alumina Fenton catalyst prepared in Example 1 of this invention;

[0030] Figure 4 The UV-Vis curve of the magnetic composite alumina Fenton catalyst prepared in Example 1 of this invention for the catalytic oxidation and degradation of methylene blue;

[0031] Figure 5 The UV-Vis curve of the magnetic composite alumina Fenton catalyst prepared in Example 2 of this invention for the catalytic oxidation and degradation of methylene blue;

[0032] Figure 6 The UV-Vis curves of the Fenton catalyst prepared in Comparative Example 1 of this invention for the catalytic oxidation and degradation of methylene blue are shown below.

[0033] Figure 7 The UV-Vis curves show the catalytic oxidation degradation of methylene blue by the Fenton catalyst prepared in Comparative Example 2 of this invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] Unless otherwise specified, the test methods or experimental methods described in the following examples are all conventional methods; unless otherwise specified, the raw materials and additives are obtained from conventional commercial sources or prepared by conventional methods.

[0036] Example 1

[0037] A method for preparing a magnetic composite alumina Fenton catalyst comprises the following steps:

[0038] S1. Preparation of Fe3O4 nanoparticles:

[0039] First, weigh 1.0 g of ferric chloride and 0.3 g of sodium citrate and dissolve them in 30 mL of ethylene glycol; then add 1.8 g of urea, sonicate to dissolve evenly, transfer to a 50 mL reaction vessel, place in an oven at 200 °C, react for 12 h, cool to room temperature after the reaction is complete, separate with a magnet, wash multiple times with deionized water and ethanol, and vacuum dry at 60 °C to obtain Fe3O4 nanoparticles;

[0040] from Figure 1 The SEM image of the prepared magnetic Fe3O4 nanoparticles shows that the nanoparticles are approximately 150 nm in size.

[0041] S2. Preparation of magnetic composite alumina carrier:

[0042] 0.06 g of polyethylene glycol and 0.2 g of sodium alginate were added to 10 mL of deionized water and heated to 60 °C until dissolved. 0.05 g of Fe3O4 nanoparticles prepared in step S1 and 1.0 g of boehmite were added and stirred until a paste-like mixture was formed. The mixture was then added dropwise to a 10 mg / mL calcium nitrate aqueous solution and allowed to stand for 6 h. The mixture was washed with deionized water and dried in an oven at 100 °C to obtain a magnetic composite alumina carrier.

[0043] from Figure 2 Optical photographs of the prepared magnetic composite alumina carrier show that the alumina composite carrier microspheres are uniformly black and about 2 mm in size.

[0044] S3. Preparation of magnetic composite alumina Fenton catalyst:

[0045] The magnetic composite alumina support prepared in step S2 was impregnated in a 4.0 mg / mL FeCl2 aqueous solution, washed with deionized water, dried in an oven at 100 °C, and calcined in a muffle furnace at 300 °C to obtain the magnetic composite alumina Fenton catalyst.

[0046] from Figure 3 The SEM image of the prepared magnetic composite alumina Fenton catalyst shows that many magnetic Fe3O4 nanoparticles are composited within the alumina support.

[0047] Weigh 40 mg of the magnetic composite alumina Fenton catalyst prepared in step S3 and add it to 20 mL of a 10 mg / L methylene blue solution. After adsorption for 0.5 h, add 0.5 mL of H2O2 to carry out the Fenton reaction.

[0048] Figure 4 The UV-Vis absorption curve of methylene blue solution over time is shown below. Figure 4 As can be seen, the concentration of methylene blue gradually decreases with time, and the reaction is complete after 2.5 hours, meaning that the degradation efficiency of methylene blue is 100%.

[0049] Example 2

[0050] A method for preparing a magnetic composite alumina Fenton catalyst comprises the following steps:

[0051] S1. Preparation of Fe3O4 nanoparticles:

[0052] First, weigh 1.0 g of ferric chloride and 0.3 g of sodium citrate and dissolve them in 30 mL of ethylene glycol; then add 1.8 g of urea, sonicate to dissolve evenly, transfer to a 50 mL reaction vessel, place in an oven at 200 °C, react for 12 h, cool to room temperature after the reaction is complete, separate with a magnet, wash multiple times with deionized water and ethanol, and vacuum dry at 60 °C to obtain Fe3O4 nanoparticles;

[0053] S2. Preparation of magnetic composite alumina carrier:

[0054] 0.06 g of polyethylene glycol and 0.2 g of sodium alginate were added to 5 mL of deionized water and heated to 60 °C until dissolved. 0.05 g of Fe3O4 nanoparticles prepared in step S1 and 1.0 g of boehmite were added and stirred until a paste-like mixture was formed. The mixture was then added dropwise to a 10 mg / mL calcium nitrate aqueous solution and allowed to stand for 6 h. The mixture was washed with deionized water and dried in an oven at 100 °C to obtain a magnetic composite alumina carrier.

[0055] S3. Preparation of magnetic composite alumina Fenton catalyst:

[0056] The magnetic composite alumina support prepared in step S2 was impregnated in a 4.0 mg / mL FeCl2 aqueous solution, washed with deionized water, dried in an oven at 100 °C, and calcined in a muffle furnace at 300 °C to obtain the magnetic composite alumina Fenton catalyst.

[0057] Weigh 40 mg of the magnetic composite alumina Fenton catalyst prepared in step S3 and add it to 20 mL of a 10 mg / L methylene blue solution. After adsorption for 0.5 h, add 0.5 mL of H2O2 to carry out the Fenton reaction.

[0058] Figure 5 The UV-Vis absorption curve of methylene blue solution over time is shown below. Figure 5 As can be seen, the concentration of methylene blue gradually decreases with time, and the reaction rate is about 75% after 2.5 hours, meaning that the degradation efficiency of methylene blue is 75% after 2.5 hours.

[0059] Comparative Example 1

[0060] A method for preparing a non-magnetic alumina Fenton catalyst comprises the following steps:

[0061] S1. Preparation of non-magnetic alumina support:

[0062] 0.06 g of polyethylene glycol and 0.2 g of sodium alginate were added to 10 mL of deionized water and heated to 60 °C until dissolved. 1 g of boehmite was added and stirred until a paste-like mixture was formed. The mixture was then added dropwise to a 10 mg / mL calcium nitrate aqueous solution and allowed to stand for 6 h. The mixture was washed with deionized water and dried in an oven at 100 °C to obtain a non-magnetic alumina carrier.

[0063] S2. Preparation of non-magnetic alumina Fenton catalyst:

[0064] The alumina support prepared in step S1 was impregnated in a 4.0 mg / mL FeCl2 aqueous solution, washed with deionized water, dried in an oven at 100 °C, and calcined in a muffle furnace at 300 °C to obtain a non-magnetic alumina Fenton catalyst.

[0065] Weigh 40 mg of the non-magnetic alumina Fenton catalyst prepared in step S2 and add it to 20 mL of a 10 mg / L methylene blue solution. After adsorption for 0.5 h, add 0.5 mL of H2O2 to carry out the Fenton reaction.

[0066] The changes in the absorption curve of the methylene blue solution were tested using UV-Vis.

[0067] Figure 6 The UV-Vis absorption curve of methylene blue solution over time is shown below. Figure 6 As can be seen, the concentration of methylene blue gradually decreases over time, and after 2.5 hours, approximately 60% of the reaction has occurred.

[0068] Comparative Example 2

[0069] A method for preparing a non-magnetic alumina Fenton catalyst comprises the following steps:

[0070] S1. Preparation of magnetic composite alumina carrier:

[0071] 0.06 g of polyethylene glycol and 0.2 g of sodium alginate were added to 10 mL of deionized water and heated to 60 °C until dissolved. 0.05 g of purchased Fe3O4 nanoparticles and 1.0 g of boehmite were added and stirred until a paste-like mixture was formed. The mixture was then added dropwise to a 10 mg / mL calcium nitrate aqueous solution and allowed to stand for 6 h. The mixture was washed with deionized water and dried in an oven at 100 °C to obtain the alumina support.

[0072] S2. Preparation of non-magnetic alumina Fenton catalyst:

[0073] The alumina support prepared in step S1 was impregnated in a 4.0 mg / mL FeCl2 aqueous solution, washed with deionized water, dried in an oven at 100 °C, and calcined in a muffle furnace at 300 °C to obtain a non-magnetic alumina Fenton catalyst.

[0074] The changes in the absorption curve of the methylene blue solution were tested using UV-Vis.

[0075] Figure 7 The UV-Vis absorption curve of methylene blue solution over time is shown below. Figure 7 As can be seen, the concentration of methylene blue gradually decreases over time, and after 2.5 hours, approximately 50% of the reaction has occurred.

[0076] Table 1 compares the physical properties and magnetic changes before and after calcination of the composite alumina Fenton catalysts prepared in Examples 1-2 and Comparative Examples 1-2.

[0077]

[0078]

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of a magnetic composite alumina Fenton catalyst in the treatment of organic pollutants in water using hydrogen peroxide solution, characterized in that, The preparation method of the magnetic composite alumina Fenton catalyst consists of the following steps: S1. Preparation of Fe3O4 nanoparticles: First, weigh 1.0 g of ferric chloride and 0.3 g of sodium citrate and dissolve them in 30 mL of ethylene glycol; then add 1.8 g of urea, sonicate to dissolve evenly, transfer to a 50 mL reaction vessel, place in an oven at 200 °C, react for 12 h, cool to room temperature after the reaction is complete, separate with a magnet, wash multiple times with deionized water and ethanol, and vacuum dry at 60 °C to obtain Fe3O4 nanoparticles; S2. Preparation of magnetic composite alumina carrier: 0.06 g of polyethylene glycol and 0.2 g of sodium alginate were added to 10 mL of deionized water and heated to 60 °C until dissolved. 0.05 g of Fe3O4 nanoparticles prepared in step S1 and 1.0 g of boehmite were added and stirred until a paste-like mixture was formed. The mixture was then added dropwise to a 10 mg / mL calcium nitrate aqueous solution and allowed to stand for 6 h. The mixture was washed with deionized water and dried in an oven at 100 °C to obtain a magnetic composite alumina carrier. S3. Preparation of magnetic composite alumina Fenton catalyst: The magnetic composite alumina support prepared in step S2 was impregnated in a 4.0 mg / mL FeCl2 aqueous solution, washed with deionized water, dried in an oven at 100 °C, and calcined in a muffle furnace at 300 °C to obtain the magnetic composite alumina Fenton catalyst.

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