Carbon fiber loaded fe3o4 composite material, preparation method and application thereof, and method for electro-fenton oxidation degradation of organic pollutants

Abstract

This invention relates to the field of electrocatalyst technology, and discloses a carbon fiber-supported Fe3O4 composite material, its preparation method and application, and a method for electro-Fenton oxidation degradation of organic pollutants. The method includes: (1) pretreating carbon fibers with hydrochloric acid to obtain pretreated carbon fibers; (2) reacting a mixed solution containing ferrous sulfate and nitrate with the pretreated carbon fibers and ammonia, allowing it to stand to obtain mixture I; and (3) heat-treating mixture I to obtain the carbon fiber-supported Fe3O4 composite material. This preparation method is simple, requires no particularly expensive equipment, can be synthesized at relatively low reaction temperatures, is easy to operate, and the resulting composite material exhibits excellent catalytic performance and stability.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst technology, specifically to a carbon fiber supported Fe3O4 composite material, its preparation method and application, and a method for electro-Fenton oxidation degradation of organic pollutants. Background Technology

[0002] In recent years, electrochemical advanced oxidation processes (EAOPs) have attracted increasing attention due to their advantages such as stable performance, ease of control, and environmental friendliness. Electro-Fenton technology generates H₂O₂ at the cathode through an electrochemical reaction, thereby achieving Fe… 2+ / Fe 3+ The catalyst is recycled to ensure the continuous operation of the reaction. The strong oxidizing hydroxyl radicals (·OH) generated by the reaction can rapidly and non-selectively degrade most recalcitrant organic pollutants into intermediates, which are then further converted into H2O and CO2.

[0003] Electro-Fenton technology generates H2O2 at the cathode through the electrochemical reduction of O2, thus avoiding the costs and risks associated with transportation and storage. Furthermore, it can achieve Fe... 2+ The recycling process continuously promotes the Fenton reaction, significantly reducing the generation of iron sludge and improving the degradation efficiency of organic pollutants. Due to its strong resistance to interference, simple operation, and high degradation and mineralization efficiency, this process is widely used to treat various types of recalcitrant organic wastewater. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon fiber-supported Fe3O4 composite material with excellent stability and catalytic activity.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for preparing carbon fiber-supported Fe3O4 composite materials, the method comprising:

[0006] (1) Pretreatment of carbon fiber (ACF) with hydrochloric acid was carried out to obtain pretreated carbon fiber;

[0007] (2) The mixed solution containing ferrous sulfate and nitrate is reacted with the pretreated carbon fiber and ammonia water, and allowed to stand to obtain mixture I;

[0008] (3) Heat-treat the mixture I to obtain the carbon fiber supported Fe3O4 composite material;

[0009] The specific surface area of ​​the carbon fiber is 1000-1200 m². 2 / g, with an average pore size of 0.5-5nm and a pore volume of 0.5-1.5cm³. 3 / g;

[0010] The molar ratio of ferrous sulfate to nitrate in the mixed solution is 0.8-1.2:1;

[0011] The reaction conditions include a temperature of 55-65℃ and a time of 60-100 min.

[0012] A second aspect of the present invention provides a carbon fiber-supported Fe3O4 composite material obtained by the method described in the first aspect.

[0013] The third aspect of this invention provides the application of the carbon fiber-supported Fe3O4 composite material described in the second aspect as a cathode material in the electro-Fenton oxidation degradation of pollutants.

[0014] The fourth aspect of the present invention provides a method for electro-Fenton oxidation degradation of organic pollutants, the method comprising the following steps: using the carbon fiber-supported Fe3O4 composite material described in the second aspect as the cathode and a platinum electrode as the anode; adding pollutants and electrolyte to an electrolytic cell, then placing the cathode and anode in the electrolyte, blowing air into the electrolyte, and applying electricity to carry out the electro-Fenton oxidation degradation reaction.

[0015] The method for preparing carbon fiber supported Fe3O4 composite material provided by this invention is simple, requires no particularly expensive equipment, can be synthesized at a relatively low reaction temperature, and is easy to operate.

[0016] The carbon fiber supported Fe3O4 composite material provided by this invention uses a specific type of carbon fiber to provide a large number of active sites for the reaction, has good adsorption and conductivity, and exhibits excellent catalytic performance and stability in the treatment of recalcitrant pollutants. It has a degradation effect on a variety of organic pollutants and has wide applicability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the principle of electro-Fenton oxidation degradation of tetracycline using carbon fiber-supported Fe3O4 composite material as the cathode and platinum sheet as the anode.

[0018] Figure 2 These are scanning electron microscope (SEM) images of the Fe3O4@ACF composite material prepared in Example 1 at different magnifications.

[0019] Figure 3 This is the energy dispersive X-ray spectrum of the Fe3O4@ACF composite material prepared in Example 1.

[0020] Figure 4 These are transmission electron microscopy (TEM) images, high-resolution transmission electron microscopy (HRTEM) images, and elemental mapping diagrams of the Fe3O4@ACF composite material prepared in Example 1.

[0021] Figure 5This is the X-ray diffraction (XRD) pattern of the Fe3O4@ACF composite material prepared in Example 1.

[0022] Figure 6 This is the X-ray photoelectron spectroscopy (XPS) spectrum of the Fe3O4@ACF composite material prepared in Example 1.

[0023] Figure 7 These are nitrogen adsorption-desorption isotherms and pore size distribution curves of the Fe3O4@ACF composite material prepared in Example 1.

[0024] Figure 8 The linear sweep voltammetry (a) and electrochemical impedance spectroscopy (b) of carbon fiber and the Fe3O4@ACF composite material prepared in Example 1 are shown.

[0025] Figure 9 This is a graph showing the stability test results of the Fe3O4@ACF composite electrode. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] As previously stated, a first aspect of the present invention provides a method for preparing carbon fiber-supported Fe3O4 composite materials, the method comprising:

[0028] (1) The carbon fiber was pretreated with hydrochloric acid to obtain pretreated carbon fiber;

[0029] (2) The mixed solution containing ferrous sulfate and nitrate is reacted with the pretreated carbon fiber and ammonia water, and allowed to stand to obtain mixture I;

[0030] (3) Heat-treat the mixture I to obtain the carbon fiber supported Fe3O4 composite material;

[0031] The specific surface area of ​​the carbon fiber is 1000-1200 m². 2 / g, with an average pore size of 0.5-5nm and a pore volume of 0.5-1.5cm³. 3 / g;

[0032] The molar ratio of ferrous sulfate to nitrate in the mixed solution is 0.8-1.2:1;

[0033] The reaction conditions include a temperature of 55-65℃ and a time of 60-100 min.

[0034] Preferably, in step (1), the hydrochloric acid is provided by a hydrochloric acid solution with a concentration of 0.08-0.12 mol / L.

[0035] The present invention does not have any special requirements on the amount of hydrochloric acid used, as long as the carbon fiber is completely soaked. Those skilled in the art can add it as needed.

[0036] Preferably, in step (1), the pretreatment conditions include: a temperature of 20-25°C and a time of 6-8 hours.

[0037] In a preferred embodiment, in step (2), the amount of the mixed solution used is 10-60 mL relative to the 2 cm × 2 cm pretreated carbon fiber.

[0038] Preferably, in step (2), the reaction operation includes: stirring a mixed solution containing ferrous sulfate and nitrate at 55-65°C for 10-30 min, and then adding the pretreated carbon fiber and ammonia water and stirring at 55-65°C for 50-70 min.

[0039] In a preferred embodiment, in step (2), the concentration of ferrous sulfate in the mixed solution is 0.1-0.2 mol / L. The inventors discovered in their research that, under this preferred embodiment, the carbon fiber-supported Fe3O4 composite material exhibits superior catalytic efficiency and catalytic stability.

[0040] Preferably, in step (2), the volume ratio of the mixed solution to the ammonia water is 9-11:1. The inventors discovered in their research that, under this preferred condition, the resulting carbon fiber-supported Fe3O4 composite material exhibits superior catalytic efficiency and catalytic stability.

[0041] Preferably, the ammonia solution is provided by an ammonia solution with a mass fraction of 28 wt%.

[0042] In a preferred embodiment, in step (2), the nitrate is potassium nitrate and / or sodium nitrate.

[0043] Preferably, in step (2), the conditions for standing include: a temperature of 20-25°C and a time of 20-24h.

[0044] In a preferred embodiment, in step (3), the heat treatment conditions include a temperature of 75-85°C and a time of 2-3 hours.

[0045] According to a preferred embodiment, the method further includes: before performing the pretreatment, ultrasonically cleaning the carbon fiber 2-3 times with deionized water, and then performing the pretreatment on the ultrasonically cleaned carbon fiber with hydrochloric acid.

[0046] According to another preferred embodiment, the method further includes: sequentially filtering, washing and drying the product after pretreatment in step (1) to obtain the pretreated carbon fiber.

[0047] The present invention does not impose any particular requirements on the filtering method. Those skilled in the art can use known technical means in the field, which will not be described in detail here. This should not be construed as a limitation of the present invention.

[0048] The present invention does not particularly limit the washing method, as long as the residual acid on the surface of the pretreated product can be removed. For example, deionized water is used to wash until the pH value is 6.5-7.5.

[0049] Preferably, the drying conditions include a temperature of 60-80°C and a time of 2-3 hours.

[0050] According to another preferred embodiment, the method further includes: before performing the heat treatment, washing the mixture I with deionized water for 2-3 minutes, and then performing the heat treatment on the mixture I after washing with deionized water.

[0051] Preferably, the average pore size of the carbon fiber supported Fe3O4 composite material is 1.7-5.0 nm.

[0052] As previously stated, the second aspect of the present invention provides a carbon fiber-supported Fe3O4 composite material prepared by the method described in the first aspect.

[0053] As previously stated, the third aspect of the present invention provides the application of the carbon fiber-supported Fe3O4 composite material described in the second aspect as a cathode material in the electro-Fenton oxidation degradation of pollutants.

[0054] As previously described, the fourth aspect of the present invention provides a method for electro-Fenton oxidation degradation of organic pollutants, the method comprising the following steps: using the carbon fiber-supported Fe3O4 composite material described in the second aspect as the cathode and a platinum electrode as the anode; adding pollutants and electrolyte to an electrolytic cell, then placing the cathode and anode in the electrolyte, blowing air into the electrolyte, and applying electricity to carry out the electro-Fenton oxidation degradation reaction.

[0055] Preferably, the pollutant is selected from at least one of tetracycline, methylene blue, methyl orange, rhodamine B, and trivalent arsenic pollutants.

[0056] This invention is in Figure 1 The paper provides a schematic diagram of the principle of electro-Fenton oxidation degradation of tetracycline using carbon fiber supported Fe3O4 composite material as cathode and platinum sheet as anode.

[0057] In a preferred embodiment, the electrolyte is provided by a 0.04-0.06 mol / L sodium sulfate solution.

[0058] Preferably, the concentration of the organic pollutant is 10-40 mg / L.

[0059] The present invention will be described in detail below through preparation examples and examples. Unless otherwise specified, the instruments, reagents, and materials involved in the following preparation examples and examples are all conventional instruments, reagents, and materials already existing in the prior art and can be obtained through legitimate commercial channels. In the following examples, room temperature refers to 22±2℃.

[0060] Carbon fiber I: 2cm × 2cm, purity 99.8%, specific surface area 1100m² 2 / g, with an average pore size of 0.5-5nm and a pore volume of 0.5-1.5cm³. 3 / g, purchased from Shandong Environmental Protection Equipment Manufacturing Company.

[0061] Carbon fiber II: 2cm × 2cm, specific surface area of ​​900m² 2 / g, surface resistivity 0.15Ω / cm 2 Purchased from Future (Jilin) ​​Materials Technology Co., Ltd.

[0062] Ammonia solution: an ammonia solution with a mass fraction of 28 wt%.

[0063] Mixed solution I: Dissolve 0.01 mol ferrous sulfate heptahydrate and 0.01 mol potassium nitrate in 60 mL distilled water and stir for 20 min to obtain mixed solution I.

[0064] Mixed solution II: Dissolve 0.02 mol ferrous sulfate heptahydrate and 0.01 mol potassium nitrate in 60 mL distilled water and stir for 20 min to obtain mixed solution II.

[0065] instrument:

[0066] Scanning electron microscope: Model: Hitachi SU4800, Manufacturer: Hitachi.

[0067] Energy-dispersive X-ray spectrometer: Model EDX-LE PLus, manufactured by Shimadzu, Japan.

[0068] Transmission electron microscope: Model JEOL JEM 2100F, manufacturer JEOL.

[0069] High-resolution transmission electron microscope: model H-9500, manufacturer: Hitachi.

[0070] X-ray diffractometer: Model: Kratos AXIS SUPRA, Manufacturer: Kratos.

[0071] Example 1

[0072] (1) Use deionized water to ultrasonically clean 2cm×2cm carbon fiber 3 times, add 0.1mol / L hydrochloric acid solution at room temperature to completely soak the carbon fiber for 7h, then filter, wash with deionized water until pH value is 7, and then dry the cleaned carbon fiber at 80℃ for 3h to obtain pretreated carbon fiber.

[0073] (2) Stir 60 mL of mixed solution I containing ferrous sulfate and potassium nitrate at 60 °C for 20 min, then add pretreated carbon fiber and 6 mL of ammonia water and react at 60 °C for 1 h. After the reaction is complete, let it stand at room temperature for 24 h to obtain mixture I.

[0074] (3) The mixture I was washed with deionized water for 3 min and then heat-treated at 80°C for 3 h to obtain carbon fiber supported Fe3O4 composite material (denoted as Fe3O4@ACF).

[0075] Comparative Example 1

[0076] The procedure is similar to that in Example 1, except that in step (2), an equal volume of mixed solution II is used to replace mixed solution I.

[0077] The remaining steps are the same as in Example 1, resulting in a carbon fiber-supported Fe3O4 composite material (denoted as Fe3O4@ACF-a).

[0078] Comparative Example 2

[0079] The process was carried out in a similar manner to Example 1, except that in step (2), 60 mL of a mixed solution I containing ferrous sulfate and potassium nitrate was stirred at 110°C for 20 min, and then pretreated carbon fiber and 6 mL of ammonia water were added and reacted at 110°C for 1 h. After the reaction was completed, the mixture was allowed to stand at room temperature for 24 h to obtain mixture I.

[0080] The remaining steps are the same as in Example 1, resulting in a carbon fiber-supported Fe3O4 composite material (denoted as Fe3O4@ACF-b).

[0081] Comparative Example 3

[0082] The procedure is similar to that in Example 1, except that in step (1), carbon fiber I is replaced with carbon fiber II of equal area.

[0083] The remaining steps are the same as in Example 1, resulting in a carbon fiber-supported Fe3O4 composite material (denoted as Fe3O4@ACF-c).

[0084] Test Example 1

[0085] The material obtained in Example 1 was subjected to structural characterization.

[0086] Figure 2 SEM images of the Fe3O4@ACF composite material prepared in Example 1 at different magnifications. Figure 2 As can be seen in (a) to (c), the samples exhibit a large number of dense ACF filaments with a diameter of 11 μm. The ACF displays a unique, interlaced rod-like fiber structure with numerous grooves on its surface. This unique morphology contributes to the material's large specific surface area and abundant active sites. (d) to (f) show the increase in ACF surface roughness after loading. Furthermore, smaller Fe3O4@ACF particles aggregate to form larger particle clusters, and a layer of Fe3O4 flocculent loading layer results in a rough and inhomogeneous microstructure on the sample surface. This result demonstrates that Fe3O4 particles have been successfully loaded onto the ACF surface.

[0087] Figure 3 The image shows the energy-dispersive X-ray diffraction (EDS) spectrum of the Fe3O4@ACF composite material prepared in Example 1. Figure 3 It can be seen that the Fe, O, C and K elements are evenly distributed in the Fe3O4@ACF composite material, and the weight percentages of C, O, Fe and K are 3.13%, 27.46%, 0.02% and 69.40%, respectively.

[0088] Figure 4 The images show TEM (ab) and HRTEM (c) images, as well as elemental mapping (d) of the Fe3O4@ACF composite material prepared in Example 1. Figure 4 As can be seen from (a) to (b), the composite material is nearly spherical and clustered on the ACF. A clear boundary can be observed between the Fe3O4 crystals and the ACF material, indicating that Fe3O4 is tightly adhered to the ACF surface. Figure 4 As can be seen from (c), the lattice spacing of the prepared Fe3O4 is 0.153 nm, corresponding to the (511) crystal plane of iron(III) oxide. Furthermore, from... Figure 4 As shown in (d), Fe3O4@ACF contains C, O, Fe, and K elements, with C, O, and Fe distributed very uniformly, while K is sparsely distributed. This further indicates that the Fe3O4@ACF composite material has been successfully constructed.

[0089] Figure 5The image shows the X-ray diffraction (XRD) pattern of the Fe3O4@ACF composite material prepared in Example 1. Figure 5 It can be seen that there are five diffraction peaks at 31.249°, 36.82°, 44.726°, 59.303°, and 65.186°, corresponding to the (220), (311), (400), (511), and (440) planes of Fe3O4, respectively, which correspond to the Fe3O4 standard card (JCPDF card number 26-1136). X-ray diffraction analysis confirmed the presence of Fe3O4 particles in the Fe3O4@ACF composite material. On the other hand, the diffraction peaks of active carbon in the X-ray diffraction spectrum are not obvious, indicating that it exists as an amorphous phase in the modified material.

[0090] Figure 6 The image shows the X-ray photoelectron spectroscopy (XPS) spectrum of the Fe3O4@ACF composite material prepared in Example 1. Figure 6 The figures below represent the total XPS spectrum, the C 1s peak, the O 1s peak, and the Fe 2p peak, respectively. Three characteristic peaks can be observed in the C 1s peak spectrum, which can be attributed to the sp atoms of carbon atoms. 2 Orbital hybridization (284.1 eV), CO (285.0 eV), O=CO (290.9 eV). The O1s peak spectrum shows three characteristic peaks: metal oxide (529.70 eV), metal hydroxide (532.83 eV), and CO bond (531.61 eV). The Fe 2p peak spectrum shows peaks for Fe 2p3 / 2 and Fe 2p1 / 2, centered at 711.2 eV and 724.9 eV respectively, close to the standard XPS data for Fe3O4. Furthermore, Fe… II and Fe III The presence of Fe on the electrode surface is determined by peaks at 710.80 eV, 712.9 eV, 724.3 eV, and 726.27 eV, while the satellite peak near 718.7 eV represents Fe in γ-Fe₂O₃. 3+ The characteristic peaks indicate that the Fe3O4 nanoparticles are partially oxidized.

[0091] The XRD and XPS results above confirm that Fe3O4 was successfully loaded onto the ACF surface.

[0092] Figure 7 The figures show (a) nitrogen adsorption-desorption isotherms and (b) pore size distribution curves of the Fe3O4@ACF composite material prepared in Example 1. Figure 7As shown in (a), the adsorption and desorption isotherms do not overlap, which is due to the presence of a large amount of carbon in the modified material, forming a hysteresis loop. According to the IUPAC classification, the modified material exhibits characteristics of a Type II adsorption isotherm with a Type H3 hysteresis loop, indicating that the pore structure of the sample typically consists of wedge-shaped pores formed by the loose stacking of lamellar particles. Figure 7 As can be seen from (b), micropores with diameters of 1.7-2.0 nm and mesopores with diameters of 2.0-5.0 nm are ubiquitous.

[0093] Test Example 2

[0094] The electrochemical performance of Fe3O4@ACF was evaluated using linear sweep voltammetry (LSV), and the test results are as follows: Figure 8 As shown. By Figure 8 As can be seen from (a), the oxygen reduction current densities of carbon fiber (ACF) and Fe3O4@ACF at -3.25V are 9.4 mA·cm⁻¹. -2 21.8mA·cm -2 This indicates that Fe3O4@ACF possesses excellent oxygen reduction activity.

[0095] Electrochemical impedance spectroscopy (EIS) was performed on ACF and Fe3O4@ACF to investigate their electrochemical properties and electron transfer capabilities. The test results are as follows: Figure 8 As shown in (b). By Figure 8 As can be seen from (b), Fe3O4@ACF has a smaller radius of curvature, indicating that Fe3O4@ACF has the smallest charge transfer resistance Rct (7.18Ω), and charge transfer is subject to a smaller resistance. Therefore, Fe3O4@ACF exhibits a higher oxygen reduction peak current density and a higher charge transfer capability, thus demonstrating good electrocatalytic activity.

[0096] Test Example 3

[0097] The Fe3O4@ACF, Fe3O4@ACF-a, Fe3O4@ACF-b, and Fe3O4@ACF-c composite materials and carbon fibers prepared in the examples were tested for catalytic degradation performance. The specific test methods are as follows:

[0098] A 250 mL electrolytic cell was used as the reaction vessel. The cathode was the test material, and the anode was a platinum sheet electrode. Both the cathode and anode electrodes were 2 cm × 2 cm in size, with an electrode spacing of 3 cm. A mixed aqueous solution (100 mL) of Na₂SO₄ (0.05 mol / L) and tetracycline hydrochloride (20 mg / L) was added to the electrolytic cell. The current was supplied by an adjustable constant voltage DC power supply. Air was then pumped into the solution at a flow rate of 200 mL / min for 120 min. Ten minutes before the experiment began, a mechanical stirrer was started for rapid mixing, and air was introduced to form an air-saturated electro-Fenton system. The current was set to 0.12 A, and the current density was set to 30 mA / cm². 2 The degradation time was 120 min. Every 30 min, the supernatant was placed in a cuvette and the tetracycline content in the solution was determined using a UV-Vis spectrophotometer to calculate the catalytic degradation efficiency.

[0099] The formula for calculating catalytic degradation efficiency is: Degradation efficiency (%) = (C0 - C) / ... t ) / C0*100%; where C0 represents the initial concentration of tetracycline, C t The concentration of tetracycline at time t is represented; the test results are shown in Table 1.

[0100] Table 1

[0101] Example number Catalytic degradation efficiency (%) after 120 min of testing carbon fiber 64.21 Example 1 82.46 Comparative Example 1 67.72 Comparative Example 2 71.35 Comparative Example 3 69.84

[0102] Test Example 4

[0103] The Fe3O4@ACF composite material from Example 1 was used as the anode and cathode for stability testing. The specific testing methods are as follows:

[0104] A 250 mL electrolytic cell was used as the reaction vessel, the cathode as the test material, and the anode as a platinum sheet electrode. The dimensions of both the cathode and anode were 2 cm × 2 cm, and the electrode spacing was 3 cm. A mixed aqueous solution (100 mL) of Na₂SO₄ (0.05 mol / L) and tetracycline hydrochloride (20 mg / L) was added to the electrolytic cell. The current was provided by an adjustable constant voltage DC power supply. Then, air was introduced into the solution at a flow rate of 200 mL / min using an air pump. After 120 min, the tetracycline content in the solution was measured using a UV spectrophotometer. The above steps were repeated five times using the same cathode test material.

[0105] Test results are as follows Figure 9 As shown. By Figure 9 It can be seen that the degradation rate of tetracycline remained at around 80% and did not significantly decrease after 5 cycles. This indicates that the Fe3O4@ACF electrode has good stability and can be reused.

[0106] Test Example 5

[0107] Referring to the method in Test Example 4, the catalytic degradation efficiency of the Fe3O4@ACF composite material in Example 1 on Rhodamine B (20 mg / L), trivalent arsenic solution (10 mg / L, obtained by dilution of trivalent arsenic standard solution), methylene blue (20 mg / L), and methyl orange (20 mg / L) was investigated. The specific test results are shown in Table 2.

[0108] Table 2

[0109] Recalcitrant pollutants Catalytic degradation efficiency (tested over 120 min) Rhodamine B 83.64％ Arsenic-containing solution 87.06％ Methyl blue 89.72％ Methyl orange 88.95％

[0110] The above results indicate that the Fe3O4@ACF composite electrode has excellent degradation efficiency and wide applicability to the degradation of various pollutants, highlighting its potential application in the treatment of various organic pollutants.

[0111] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing carbon fiber-supported Fe3O4 composite materials, characterized in that, The method includes: (1) The carbon fiber was pretreated with hydrochloric acid to obtain pretreated carbon fiber; (2) The mixed solution containing ferrous sulfate and nitrate is reacted with the pretreated carbon fiber and ammonia water, and allowed to stand to obtain mixture I; (3) Heat-treat the mixture I to obtain the carbon fiber supported Fe3O4 composite material; The specific surface area of ​​the carbon fiber is 1000-1200 m². 2 / g, with an average pore size of 0.5-5nm and a pore volume of 0.5-1.5cm³. 3 / g; The molar ratio of ferrous sulfate to nitrate in the mixed solution is 0.8-1.2:1; The concentration of ferrous sulfate in the mixed solution is 0.1-0.2 mol / L; The nitrate is potassium nitrate and / or sodium nitrate; The reaction conditions include a temperature of 55-65℃ and a time of 60-100 min.

2. The method according to claim 1, characterized in that, In step (1), the hydrochloric acid is provided by a hydrochloric acid solution with a concentration of 0.08-0.12 mol / L; and / or In step (1), the pretreatment conditions include: a temperature of 20-25°C and a time of 6-8 hours.

3. The method according to claim 1 or 2, characterized in that, In step (2), the amount of the mixed solution used is 10-60 mL relative to the 2 cm × 2 cm pretreated carbon fiber; and / or In step (2), the volume ratio of the mixed solution to the ammonia water is 9-11:

1.

4. The method according to claim 1 or 2, characterized in that, In step (3), the heat treatment conditions include: a temperature of 75-85℃ and a time of 2-3h.

5. The method according to claim 1 or 2, characterized in that, The method further includes: washing and drying the product after pretreatment in step (1) in sequence to obtain the pretreated carbon fiber.

6. The carbon fiber-supported Fe3O4 composite material prepared by the method according to any one of claims 1-5.

7. The application of the carbon fiber supported Fe3O4 composite material as a cathode material in the electro-Fenton oxidation degradation of pollutants as described in claim 6.

8. A method for electro-Fenton oxidation degradation of organic pollutants, characterized in that, The method includes the following steps: using the carbon fiber-supported Fe3O4 composite material of claim 6 as the cathode and a platinum electrode as the anode; adding contaminants and electrolyte to the electrolytic cell, then placing the cathode and anode in the electrolyte, blowing air into the electrolyte, and applying electricity to carry out an electro-Fenton oxidation degradation reaction.

9. The method according to claim 8, characterized in that, The pollutant is selected from at least one of tetracycline, methylene blue, methyl orange, rhodamine B, and trivalent arsenic pollutants.

10. The method according to claim 8 or 9, characterized in that, The electrolyte is provided by a 0.04-0.06 mol / L sodium sulfate solution; The concentration of the organic pollutant is 10-40 mg / L.

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