Carbon fiber loaded Fe3O4 composite material, preparation method and application thereof, and method for degrading organic pollutants by electro-Fenton oxidation

Abstract

The invention relates to the technical field of electrocatalysts, and discloses a carbon fiber loaded Fe3O4 composite material, a preparation method and application thereof, and a method for degrading organic pollutants through electro-Fenton oxidation. The method comprises the following steps: (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 water, and standing to obtain a mixture I; and (3) carrying out heat treatment on the mixture I to obtain the carbon fiber loaded Fe3O4 composite material. The preparation method is simple, particularly expensive equipment is not needed, synthesis can be performed at a relatively low reaction temperature, operation is easy, and the prepared composite material has excellent catalytic performance and stability.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysts, and particularly relates to a carbon fiber supported Fe3O4 composite material, a preparation method and application thereof, and a method for electro-Fenton oxidation degradation of organic pollutants. Background Art

[0002] In recent years, electrochemical advanced oxidation processes (EAOPs) have received increasing attention due to their advantages such as stable performance, easy control, and environmental friendliness. The electro-Fenton technology generates H2O2 at the cathode through an electrochemical reaction and realizes the recycling of Fe 2+ / Fe 3+ catalyst, enabling the reaction to proceed continuously. The strongly oxidizing hydroxyl radicals (·OH) generated by the reaction can rapidly and non-selectively degrade most refractory organic pollutants into intermediates, and then further convert these intermediates into H2O and CO2.

[0003] The electro-Fenton technology generates H2O2 at the cathode by electrochemically reducing O2, thus avoiding the costs and risks of transportation and storage. In addition, it can achieve the recycling of Fe 2+ , continuously promote the Fenton reaction, greatly reduce the generation of iron sludge, and improve the degradation efficiency of organic pollutants. Due to the strong anti-interference ability, simple operation, and high degradation and mineralization efficiency of this process, it is widely used in the treatment of various refractory organic wastewater. Summary of the Invention

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

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

[0006] (1) Pretreating carbon fiber (ACF) with hydrochloric acid to obtain pretreated carbon fiber;

[0007] (2) Reacting a mixed solution containing ferrous sulfate and nitrate with the pretreated carbon fiber and ammonia water, standing, to obtain mixture I;

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

[0009] Wherein, the specific surface area of the carbon fiber is 1000 - 1200m 2 / g, the average pore diameter is 0.5 - 5nm, and the pore volume is 0.5 - 1.5cm 3 / g;

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

[0011] The conditions of the reaction include: the temperature is 55 - 65 °C, and the time is 60 - 100 min.

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

[0013] 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.

[0014] The fourth aspect of the present invention provides a method for electro-Fenton oxidation degradation of organic pollutants, which includes 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 into the electrolytic cell, then placing the cathode and anode in the electrolyte, introducing air into the electrolyte, and energizing for electro-Fenton oxidation degradation reaction.

[0015] The preparation method of the carbon fiber supported Fe3O4 composite material provided by the present invention is simple, does not require 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 the present invention can provide a large number of active sites for the reaction by using a specific type of carbon fiber, has good adsorption and conductivity, has excellent catalytic performance and stability in the treatment of refractory pollutants, has a degradation effect on a variety of organic pollutants, and has wide applicability. Description of the Drawings

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

[0018] Figure 2 is a scanning electron microscope (SEM) image of the Fe3O4@ACF composite material prepared in Example 1 at different magnification ratios.

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

[0020] Figure 4 is a transmission electron microscope (TEM) image, a high-resolution transmission electron microscope (HRTEM) image, and an elemental mapping image of the Fe3O4@ACF composite material prepared in Example 1.

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

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

[0023] Figure 7 It is the nitrogen adsorption-desorption isotherm pattern and pore size distribution curve pattern of the Fe3O4@ACF composite material prepared in Example 1.

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

[0025] Figure 9 It is the stability test result pattern of the Fe3O4@ACF composite electrode. Detailed implementation manners

[0026] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0027] As described above, the first aspect of the present invention provides a method for preparing a carbon fiber supported Fe3O4 composite material, and the method includes:

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

[0029] (2) Reacting a mixed solution containing ferrous sulfate and nitrate with the pretreated carbon fiber and ammonia water, and standing to obtain mixture I;

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

[0031] Wherein, the specific surface area of the carbon fiber is 1000-1200 m 2 / g, the average pore diameter is 0.5-5 nm, and the pore volume is 0.5-1.5 cm 3 / g;

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

[0033] The conditions of the reaction include: temperature is 55 - 65°C, and time is 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 has no special requirements for the dosage of the hydrochloric acid, as long as the carbon fiber can be completely soaked, and those skilled in the art can add it according to needs.

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

[0037] Preferably, in step (2), relative to the pretreated carbon fiber of 2 cm × 2 cm, the dosage of the mixed solution is 10 - 60 mL.

[0038] Preferably, in step (2), the operation of the reaction includes: stirring the 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] Preferably, in step (2), the concentration of ferrous sulfate in the mixed solution is 0.1 - 0.2 mol / L. The inventors found in the research that in this preferred case, the prepared carbon fiber supported Fe3O4 composite material has more excellent catalytic efficiency and catalytic stability.

[0040] Preferably, in step (2), the volume ratio of the dosage of the mixed solution to the ammonia water is 9 - 11:1. The inventors found in the research that in this preferred case, the prepared carbon fiber supported Fe3O4 composite material has more excellent catalytic efficiency and catalytic stability.

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

[0042] Preferably, in step (2), the nitrate is potassium nitrate and / or sodium nitrate.

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

[0044] Preferably, in step (3), the conditions of the heat treatment include: temperature is 75 - 85°C, and time is 2 - 3 h.

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

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

[0047] The present invention has no particular requirements for the filtering method, and those skilled in the art can adopt known technical means in the art to perform it, which will not be elaborated here. Those skilled in the art should not understand it as a limitation to the present invention.

[0048] The present invention has no particular limitation on the washing method with water, as long as the residual acid on the surface of the product after the pretreatment can be removed. Exemplarily, it is washed with deionized water 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 h.

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

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

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

[0053] As described above, 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 described above, the fourth aspect of the present invention provides a method for electro-Fenton oxidation degradation of organic pollutants, which includes 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 into the electrolytic cell, then placing the cathode and anode in the electrolyte, introducing air into the electrolyte, and energizing for electro-Fenton oxidation degradation reaction.

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

[0056] The present invention is inFigure 1 Figure 1 shows a schematic diagram of the principle of electro-Fenton oxidation for the degradation of tetracycline using a carbon fiber-supported Fe3O4 composite as the cathode and a platinum sheet as the anode.

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

[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. In the following preparation examples and examples, unless otherwise specified, the instruments, reagents, materials, etc. involved are all conventional instruments, reagents, materials, etc. existing in the prior art and can be obtained through regular commercial channels. In the following examples, room temperature refers to 22 ± 2°C.

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

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

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

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

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

[0065] Instruments:

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

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

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

[0069] High-resolution transmission electron microscope: Model is Hitachi H-9500, and the manufacturer is Hitachi.

[0070] X-ray diffractometer: Model is Kratos AXIS SUPRA, and the manufacturer is Kratos.

[0071] Example 1

[0072] (1) The carbon fiber with a size of 2 cm × 2 cm was ultrasonically cleaned 3 times with deionized water, then completely immersed in a 0.1 mol / L hydrochloric acid solution at room temperature for 7 h, and then filtered. It was washed with deionized water until the pH value reached 7, and then the washed carbon fiber was dried at 80 °C for 3 h to obtain the pretreated carbon fiber.

[0073] (2) 60 mL of mixed solution I containing ferrous sulfate and potassium nitrate was stirred at 60 °C for 20 min, then the pretreated carbon fiber and 6 mL of ammonia water were added, and the reaction was carried out at 60 °C for 1 h. After the reaction was completed, it was left standing 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 the carbon fiber-supported Fe3O4 composite material (denoted as Fe3O4@ACF).

[0075] Comparative Example 1

[0076] It was carried out in a similar method to Example 1. The difference is that in step (2), an equal volume of mixed solution II was used to replace mixed solution I.

[0077] The remaining steps were the same as those in Example 1 to obtain the carbon fiber-supported Fe3O4 composite material (denoted as Fe3O4@ACF-a).

[0078] Comparative Example 2

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

[0080] The remaining steps were the same as those in Example 1 to obtain the carbon fiber-supported Fe3O4 composite material (denoted as Fe3O4@ACF-b).

[0081] Comparative Example 3

[0082] It was carried out in a similar method to Example 1. The difference is that in step (1), carbon fiber II with an equal area was used to replace carbon fiber I.

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

[0084] Test Example 1

[0085] The material prepared in the foregoing Example 1 was subjected to structural characterization.

[0086] Figure 2 FIG. 11 shows SEM images of the Fe3O4@ACF composite material prepared in Example 1 at different magnification ratios. Figure 2 It can be seen that in (a) to (c), the sample shows a large number of dense ACF filaments with a diameter of 11 μm. The ACF exhibits a unique, interlaced rod-like fiber structure with many grooves on the surface. This unique morphology contributes to the large specific surface area and rich active sites of the material. (d) to (f) show the increase in the surface roughness of the ACF after loading. In addition, smaller Fe3O4@ACF particles aggregate to form larger-sized particle clusters, as well as a layer of Fe3O4 flocculent loading layer, resulting in the roughness and non-uniformity of the surface microstructure of the sample. This result indicates that Fe3O4 particles have been successfully loaded onto the ACF surface.

[0087] Figure 3 FIG. 12 shows the energy-dispersive X-ray spectrum (EDS energy spectrum) of the Fe3O4@ACF composite material prepared in Example 1. Figure 3 It can be seen that the distributions of Fe, O, C, and K elements in the Fe3O4@ACF composite material are uniform, and the weight percentages of C, O, Fe, and K are 3.13%, 27.46%, 0.02%, and 69.40%, respectively.

[0088] Figure 4 FIG. 13 shows the TEM (a-b), HRTEM (c), and elemental mapping (d) images of the Fe3O4@ACF composite material prepared in Example 1. Figure 4 From (a) to (b), it can be seen that the composite material is close to spherical and is loaded on the ACF in clusters. An obvious boundary can be observed between the Fe3O4 crystal and the ACF material, indicating that Fe3O4 adheres tightly to the ACF surface. Figure 4 From (c), it can be seen that the prepared Fe3O4 lattice spacing is 0.153 nm, corresponding to the (511) crystal plane of magnetite. Figure 4 In addition, from (d), it can be seen that C, O, Fe, and K elements are present in Fe3O4@ACF, among which the distributions of C, O, and Fe are very uniform, and K is sporadically distributed. This further indicates that the Fe3O4@ACF composite material has been successfully constructed.

[0089] Figure 5XRD pattern of the Fe3O4@ACF composite material prepared in Example 1. As shown by Figure 5 the XRD pattern, five diffraction peaks are observed 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 can match with the Fe3O4 standard card (JCPDF card No. 26 - 1136). X-ray diffraction analysis confirms the presence of Fe3O4 particles in the Fe3O4@ACF composite material. On the other hand, the diffraction peaks of activated carbon in the X-ray diffraction spectrum are not obvious, indicating its existence as an amorphous phase in the modified material.

[0090] Figure 6 XPS spectrum of the Fe3O4@ACF composite material prepared in Example 1. The figures respectively showing the total XPS spectrum, C 1s peak, O 1s peak, and Fe 2p peak are presented in Figure 6 . Three characteristic peaks can be observed in the C1s peak spectrum, which can be attributed to the sp 2 orbital hybridization of carbon atoms (284.1 eV), C - O (285.0 eV), and O=C - O (290.9 eV) respectively. In the O1s peak spectrum, three characteristic peaks of metal oxide (529.70 eV), metal hydroxide (532.83 eV), and C - O bond (531.61 eV) are shown. In the Fe 2p peak spectrum, the peaks of Fe 2p3 / 2 and Fe 2p1 / 2 are shown, with the centers located at 711.2 eV and 724.9 eV respectively, close to the standard XPS data of Fe3O4. In addition, the presence of Fe II and Fe III on the electrode surface is determined by the peaks at 710.80 eV, 712.9 eV, 724.3 eV, and 726.27 eV. The satellite peak located near 718.7 eV is the characteristic peak of Fe 3+ in γ-Fe2O3, indicating that the Fe3O4 nanoparticles are partially oxidized.

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

[0092] Figure 7 (a) Nitrogen adsorption - desorption isotherm diagram and (b) pore size distribution curve diagram of the Fe3O4@ACF composite material prepared in Example 1. As shown in Figure 7As shown in (a), the adsorption and desorption isotherms do not overlap with each other, which is due to the formation of a hysteresis loop due to the presence of a large amount of carbon in the modified material. According to the IUPAC classification, the modified material exhibits the characteristics of a type II adsorption isotherm with an H3-type hysteresis loop, indicating that the pore structure of the sample is usually composed of wedge-shaped pores formed by the loose packing of flaky particles. From Figure 7 As can be seen from (b), the prevalence of micropores with diameters of 1.7 - 2.0 nm and mesopores with diameters of 2.0 - 5.0 nm.

[0093] Test Example 2

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

[0095] Electrochemical impedance spectroscopy (EIS) tests were carried out on ACF and Fe3O4@ACF to explore their electrochemical properties and electron transfer capabilities, and the test results are as Figure 8 shown in (b). As can be seen from Figure 8 (b), Fe3O4@ACF has a smaller arc radius, which indicates that Fe3O4@ACF has the smallest charge transfer resistance Rct (7.18 Ω), and the charge transfer is subject to a smaller resistance. Therefore, Fe3O4@ACF has a higher oxygen reduction peak current density and a higher charge transfer ability, thus showing good electrocatalytic activity.

[0096] Test Example 3

[0097] The catalytic degradation performance tests of the Fe3O4@ACF, Fe3O4@ACF-a, Fe3O4@ACF-b, Fe3O4@ACF-c composite materials, and carbon fiber prepared in the examples were carried out. The specific test method is 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. The sizes of the cathode and anode plates were both 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 for 120 min. 10 minutes before the start of the experiment, 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 / cm 2 , and the degradation time was 120 min. Every 30 min, the supernatant was placed in a cuvette, and the content of tetracycline in the solution was measured using a UV-visible spectrophotometer to calculate the catalytic degradation efficiency.

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

[0100] Table 1

[0101] Example number Catalytic degradation efficiency at 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 stability of the Fe3O4@ACF composite material as the cathode and anode in Example 1 was tested. The specific test method was as follows:

[0104] 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. The sizes of the cathode and anode were both 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 content of tetracycline in the solution was tested using a UV spectrophotometer, and the above steps were repeated five times using the same cathode test material.

[0105] The test results are as Figure 9 shown. It can be seen from Figure 9 that the degradation rate of tetracycline remained at about 80%, and there was no obvious decrease during 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 of Test Example 4, the catalytic degradation efficiency of the Fe3O4@ACF composite material of Example 1 for rhodamine B (20 mg / L), trivalent arsenic solution (10 mg / L, diluted from 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] Refractory pollutant Catalytic degradation efficiency (testing for 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 broad applicability for the degradation of various pollutants, highlighting its potential application in treating 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 technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing a carbon fiber-supported Fe3O4 composite material, characterized in that, The method includes: (1) Pretreating carbon fiber with hydrochloric acid to obtain pretreated carbon fiber; (2) Reacting a mixed solution containing ferrous sulfate and nitrate with the pretreated carbon fiber and ammonia water, standing still, to obtain Mixture I; (3) Heat-treating the Mixture I to obtain the carbon fiber supported Fe3O4 composite material; Among them, the specific surface area of the carbon fiber is 1000-1200m 2 / g, the average pore diameter is 0.5-5nm, and the pore volume is 0.5-1.5cm 3 / g; The molar ratio of the content of ferrous sulfate to nitrate in the mixed solution is 0.8 - 1.2:1; The conditions of the reaction include: the temperature is 55 - 65°C, and the time is 60 - 100 min.

2. The method according to claim 1, wherein 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 conditions of the pretreatment include: the temperature is 20 - 25°C, and the time is 6 - 8 h.

3. The method according to claim 1 or 2, characterized in that, In step (2), relative to the pretreated carbon fiber of 2 cm×2 cm, the dosage of the mixed solution is 10 - 60 mL; and / or In step (2), the concentration of ferrous sulfate in the mixed solution is 0.1 - 0.2 mol / L; and / or In step (2), the nitrate is potassium nitrate and / or sodium nitrate; and / or In step (2), the volume ratio of the dosage of the mixed solution to the ammonia water is 9 - 11:

1.

4. The method according to any one of claims 1 to 3, characterized in that In step (3), the conditions of the heat treatment include: the temperature is 75 - 85°C, and the time is 2 - 3 h.

5. The method according to any one of claims 1-4, characterized in that The method further includes: successively washing and drying the product after the pretreatment in step (1) 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. Application of the carbon fiber supported Fe3O4 composite material according to claim 6 as a cathode material in the electro-Fenton oxidation for degrading pollutants.

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

9. The method according to claim 8, wherein The pollutants are 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 sodium sulfate solution with a concentration of 0.04 - 0.06 mol / L; The concentration of the organic pollutant is 10 - 40 mg / L.

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