An oil-water separation material with photocatalytic self-purification ability and its preparation method and application

Abstract

The present invention provides an oil-water separation material with photocatalytic self-purification ability, a preparation method and application thereof, and belongs to the technical field of oil-water separation and wastewater treatment. The preparation method of the oil-water separation material is as follows: a carbon nitride precursor and a carbon fiber material are subjected to a chemical vapor deposition method under heating conditions to obtain a CN / CF composite material in which carbon nitride is coated on the surface of the carbon fiber; in an inert gas atmosphere, a surface modification material is reacted with the CN / CF composite material under heating conditions to obtain an oleophilic and hydrophobic oil-water separation material. The preparation method has a simple process, a simple raw material composition, and a short synthesis time, so the production cost is low and it is suitable for industrial-scale production. The oil-water separation material prepared by this method has strong hydrophobicity, a stable structure, high separation flux and efficiency, can be recycled, and has the ability to degrade organic pollutants under visible light, so it has the ability to self-purify and resist oil stains.

Description

Technical Field

[0001] The present invention belongs to the fields of oil-water separation technology and organic wastewater treatment technology, and particularly relates to an oil-water separation material with photocatalytic self-purification capability, a preparation method and application thereof. Background Art

[0002] Oil spills and the discharge of industrial and domestic oily wastewater, on the one hand, cause severe damage to the ecological environment and water bodies, posing a threat to the health of humans and other organisms; on the other hand, they also result in a significant waste of energy and industrial raw materials. Commonly used oily wastewater treatment methods suffer from low separation efficiency, high energy consumption, high costs, and waste of oil resources. Therefore, it is necessary to develop oil-water separation materials with high oil-water separation efficiency and low cost.

[0003] Currently, the main technologies used in the oil-water separation field include air flotation, centrifugation, coagulation, and adsorption separation. However, these methods are complex, costly, have low separation efficiency, and are prone to secondary contamination. Atmospheric pressure filtration separation offers high capacity and rapid separation, but it still faces challenges such as high material costs and the susceptibility of filter materials to scaling and contamination, which reduces the service life of the filter materials.

[0004] Chinese patent application publication CN115054948A discloses a visible-light-driven self-cleaning carbon nitride heterojunction oil-water separation membrane, preparation method, and application. The oil-water separation membrane includes a modified layer formed on the surface of a substrate membrane; the modified layer is obtained by self-assembly of a heterojunction nanomaterial and graphene oxide, and the heterojunction nanomaterial is obtained by in-situ growth of an iron-based MOF material on the carbon nitride surface. The composite membrane has excellent oil-water separation performance and visible-light-driven self-cleaning performance. However, the oil-water separation membrane is composed of pre-synthesized carbon nitride heterojunction powder supported on a support membrane substrate. Since the carbon nitride and the support membrane substrate are connected by physical adsorption, it easily falls off the substrate, especially when flushed by an oil-water mixture, resulting in its cycle life needing to be further improved. In addition, when using this composite membrane for oil-water separation, pressure must be applied to drive it; the preparation time of this composite membrane is long, and the production cost is high. Summary of the Invention

[0005] To address the above-mentioned issues, the present invention provides an oil-water separation material with photocatalytic self-purification capabilities and a method for preparing the same. The method for preparing the oil-water separation material of the present invention features a simple process and a short synthesis cycle. The oil-water separation material prepared by this method exhibits hydrophobicity, enabling atmospheric oil-water separation. When used for oil-water separation, it exhibits high oil flux and separation efficiency, as well as excellent stability and self-purification capabilities.

[0006] Specifically, in order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] A method for preparing an oil-water separation material with photocatalytic self-purification capability comprises the following steps:

[0008] S1. Using a carbon nitride precursor to react with a carbon fiber material under heating conditions to prepare a CN / CF material in which carbon nitride is coated on the surface of the carbon fiber;

[0009] S2. In an inert gas atmosphere, reacting the surface modification material with the CN / CF material under heating conditions to obtain the oil-water separation material;

[0010] The surface modification material is at least one of benzyl alcohol, phenylethyl alcohol, phenol, n-heptanol, and n-octanol.

[0011] A carbon nitride precursor refers to a compound that easily decomposes at high temperatures to produce a gaseous intermediate product and can deposit and grow carbon nitride on a substrate material. In the present invention, a carbon nitride nanolayer is in situ synthesized on the surface of a carbon fiber material by chemical vapor deposition or gas-assisted deposition at high temperatures, obtaining a composite material CN / CF in which the carbon fiber surface is tightly coated with carbon nitride, which can overcome the material instability caused by physical compounding. Then, under an inert gas atmosphere, the surface of the CN / CF material is modified using an organic compound with a strong polarity at one end and a strong non-polarity at the other end, such as benzyl alcohol, phenylethyl alcohol, or phenol, thereby regulating the material from hydrophilicity to hydrophobicity.

[0012] In a preferred embodiment of the present invention, the mass ratio of the carbon nitride precursor to the carbon fiber material is 1:(1.5-2.0).

[0013] In a preferred embodiment of the present invention, the mass ratio of the surface modification material to the CN / CF material is (0.5-1):1.

[0014] In a preferred embodiment of the present invention, the carbon nitride precursor is at least one of melamine, urea, cyanamide, and dicyandiamide.

[0015] In a preferred embodiment of the present invention, the carbon fiber material comprises at least one of graphite carbon felt, carbon paper, and carbon nanotubes, wherein the carbon nanotubes are preferably multi-walled carbon nanotubes.

[0016] In a further preferred embodiment, the carbon fiber material is graphite carbon felt with a thickness of 0.2 to 0.8 cm.

[0017] In a preferred embodiment of the present invention, the reaction under heating conditions in step S1 refers to the reaction at 450° C. to 600° C. for 2 to 4 hours.

[0018] In a further preferred embodiment, the heating rate in step S1 is 2.5°C to 5.0°C / min.

[0019] In a preferred embodiment of the present invention, the reaction under heating conditions in step S2 refers to the reaction at 200° C. to 350° C. for 1 to 2 hours.

[0020] In a further preferred embodiment, the heating rate in step S2 is 5.0°C to 10.0°C / min.

[0021] The oil-water separation material with photocatalytic self-purification capability prepared by any of the above-mentioned preparation methods can perform oil-water separation under normal pressure gravity drive or external pressure drive.

[0022] In a preferred embodiment, the oil phase of the oil-water separation material when used for oil-water separation includes at least one of dichloromethane, chloroform, toluene, n-heptane, cyclohexane, and petroleum ether.

[0023] The oil-water separation material with photocatalytic self-purification ability prepared by any of the preparation methods described above can degrade organic pollutants under visible light catalysis. Therefore, the oil-water separation material has the ability to self-purify and degrade oil stains so that it can be recycled, and can also be used alone for photocatalytic degradation treatment of wastewater containing organic pollutants.

[0024] Compared with the prior art, the present invention has the following advantages: (1) The process for preparing the oil-water separation material in the present invention is simple, the raw material composition is simple, and the synthesis time is short, so the production cost is low, and the material is suitable for industrial-scale production and can be applied to the industrial-scale oil-water separation industry. (2) The separation flux and separation efficiency of the oil-water separation material prepared in the present invention are both very high, and the minimum separation flux can reach 38102.1±2126L·m -2 ·h -1 In the preferred solution, the separation flux can reach 429333.2±13577L·m -2 ·h -1 , the minimum separation efficiency can reach more than 97%, and can even reach more than 99%. (3) The oil-water separation material prepared by the present invention has strong hydrophobicity, and the water contact angle reaches more than 150°; and it has good stability and can be recycled. The separation efficiency after 55 cycles of oil-water separation can still reach more than 97%. (4) The oil-water separation material prepared by the present invention can degrade organic matter under visible light catalysis, so it has self-cleaning ability, can be recycled, and can also be used for the treatment of wastewater containing organic pollutants. (5) The photocatalyst in the oil-water separation material prepared by the present invention is connected to the substrate through a chemical bond, has anti-scouring ability, good stability, and has the ability to be used for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1Graph showing the water contact angle measurements of the oil-water separation materials prepared in Examples 1 to 3;

[0026] Figure 2 The results of flux and separation efficiency measurement of the composite material CNBA / CF prepared in Example 1 for separating different oil-water mixtures are shown in FIG.

[0027] Figure 3 This is a graph showing the results of measuring the mass absorption capacity of the composite material CNBA / CF prepared in Example 1 when separating different oil-water mixtures;

[0028] Figure 4 This is a graph showing the volume absorption capacity of the composite material CNBA / CF prepared in Example 1 when separating different oil-water mixtures;

[0029] Figure 5 Graph showing the separation flux and separation efficiency of a mixture of dichloromethane and water when the composite materials CNBA / CF with different thicknesses prepared according to the method of Example 1 are used to separate the mixture;

[0030] Figure 6 This is a graph showing the stability test results of the composite material CNBA / CF prepared in Example 1 when subjected to cyclic adsorption of a mixture of dichloromethane and water and a mixture of petroleum ether and water;

[0031] Figure 7 Graph showing the separation flux and separation efficiency of the composite material CNBA / CF prepared in Example 1 when performing oil-water separation on a mixture of dichloromethane and water under various harsh conditions;

[0032] Figure 8 This is a diagram showing the photocatalytic degradation effect of the composite material CNBA / CF prepared according to the method of Example 1 on Bengal Rose Red in solution and air;

[0033] Figure 9 The UV-vis spectra of the Bengal rose red aqueous solution under different illumination times during the photocatalytic degradation of Bengal rose red by CNBA / CF in aqueous solution;

[0034] Figure 10 The UV-vis spectra of the eluted solution of Rose Bengal at different illumination times were obtained by photocatalytic degradation of adsorbed Rose Bengal by CNBA / CF in air atmosphere.

[0035] Figure 11 These are SEM images of the surface (a) and cross-section (b) of the oil-water separation material prepared in Example 1. DETAILED DESCRIPTION

[0036] The following is a clear and complete description of the technical solutions of the present invention in conjunction with the embodiments, so that those skilled in the art can fully understand the present invention. Obviously, the embodiments described are only some preferred embodiments of the present invention, rather than all embodiments. Any equivalent transformations or substitutions made by those skilled in the art to the following embodiments without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a method for preparing an oil-water separation material having photocatalytic self-purification capability, comprising the following steps:

[0039] S1. Place 0.5g of melamine powder at the bottom of a test tube and cut graphite carbon felt (with a mass ratio of 1.5:1) inside the test tube near the tube mouth. Heat the test tube in a muffle furnace to 600°C at a heating rate of 5.0°C / min and hold at 600°C for 4 hours. Then cool naturally to room temperature to obtain a carbon fiber composite material (CN / CF) coated with carbon nitride.

[0040] S2. Place 0.5g of benzyl alcohol at the bottom of another test tube, and place the CN / CF composite material prepared in step S1 inside the test tube near the tube mouth (the mass ratio of benzyl alcohol to CN / CF composite material is 0.5:1). The test tube is placed in a tubular muffle furnace under a nitrogen atmosphere, heated to 300°C at a heating rate of 5.0°C / min, and maintained at 300°C for 1h; then naturally cooled to room temperature to obtain a composite material CNBA / CF hydrophobically modified with benzyl alcohol, which is the oil-water separation material of this embodiment. The prepared composite material CNBA / CF is observed with a scanning electron microscope (SEM), and its structure is as shown Figure 11 shown. Figure 11 Figure (a) shows the surface of the CNBA / CF composite material, and Figure (b) shows a cross-sectional image of the CNBA / CF composite material. As can be seen from the figures, the overall structure of the material is uniform and dense, with the benzyl alcohol-modified carbon nitride evenly coated on the surface of the carbon fiber material.

[0041] Example 2

[0042] This embodiment provides a method for preparing an oil-water separation material having photocatalytic self-purification capability, comprising the following steps:

[0043] S1. Place 0.5g of urea powder at the bottom of a test tube and place multi-walled carbon nanotubes (5-15nm long) inside the test tube near the tube end (the mass ratio of urea to carbon nanotubes is 1:2). Place the test tube in a muffle furnace and heat it to 450°C at a heating rate of 2.5°C / min. Hold at 450°C for 3 hours; then cool naturally to room temperature to obtain a carbon fiber composite material coated with carbon nitride, CN / CF.

[0044] S2. Place 0.5 g of phenylethanol at the bottom of another test tube and place the CN / CF composite material prepared in step S1 inside the test tube near the tube mouth (the mass ratio of phenylethanol to CN / CF composite material is 1:1). Place the test tube in a tubular muffle furnace under an argon atmosphere and heat to 350°C at a heating rate of 7.5°C / min. Hold at 350°C for 1.5 hours; then naturally cool to room temperature to obtain the CNPA / CF composite material hydrophobically modified with phenylethanol, which is the oil-water separation material of this embodiment.

[0045] Example 3

[0046] This embodiment provides a method for preparing an oil-water separation material having photocatalytic self-purification capability, comprising the following steps:

[0047] S1. Place 0.5g of dicyandiamide powder at the bottom of a test tube and place the cut carbon paper inside the test tube near the tube end (the mass ratio of dicyandiamide to carbon paper is 1:1.75). Place the test tube in a muffle furnace and heat to 550°C at a heating rate of 4°C / min. Hold at 550°C for 2 hours; then cool naturally to room temperature to obtain a carbon fiber composite material coated with carbon nitride, CN / CF.

[0048] S2, 0.5g phenol is placed at the bottom of another test tube, and the composite material CN / CF prepared in step S1 is placed inside the test tube near the position of the tube mouth (the mass ratio of phenol to CN / CF composite material is 0.75: 1). The test tube is placed in a tubular muffle furnace under an air atmosphere, heated to 200°C at a heating rate of 10.0°C / min, and kept at 200°C for 2h; then naturally cooled to room temperature, and obtained a phenol-modified composite material CNP / CF, which is the oil-water separation material of the present embodiment.

[0049] Example 4

[0050] This example studies the water contact angle, oil flux, separation efficiency, adsorption capacity, stability and self-cleaning ability of the oil-water separation material, as well as the effect of material thickness on the oil flux and separation efficiency.

[0051] 1. Measure water contact angle

[0052] The contact angles of the oil-water separation materials CNBA / CF, CNPA / CF, CNP / CF prepared in Examples 1 to 3 and the CN / CF material prepared in Example 1 were tested using a contact angle tester (model: SL200KS). The results were 152.0°, 153.4°, 150.1°, 0° (as shown in Figure 2). Figure 1 From Figure 1 It can be seen from the figure that the water contact angle of the CN / CF material modified with benzyl alcohol, phenylethanol and phenol changed from 0° to more than 150°, indicating that the CN / CF material changed from super hydrophilicity to hydrophobicity after modification.

[0053] 2. Measure the flux and separation efficiency of different oil-water mixtures

[0054] 2.1 Measuring oil flux

[0055] The oil-water separation material CNBA / CF prepared in Example 1 was used to separate a mixture of dichloromethane (DCM) and water in a volume ratio of 1:1, a mixture of chloroform and water in a volume ratio of 1:1, a mixture of toluene and water in a volume ratio of 5:1, a mixture of heptane and water in a volume ratio of 5:1, a mixture of cyclohexane and water in a volume ratio of 5:1, and a mixture of petroleum ether and water in a volume ratio of 5:1. The volume of the organic solvent after separation was measured according to the method in "Two-dimensional fluorinated covalent organic frameworks with tunable hydrophobicity for ultrafast oil-water separation" (DOI: 10.1002 / ange.202113348), and the separation time was measured at the same time. The flux was calculated according to the following formula: F = V / (s·Δt). In the formula, F is the liquid flux in L·m -2 ·h -1 ; V is the volume of the permeate, in L; s is the effective area, in m 2 ; Δt is the penetration time, in hours. The measurement results are as follows Figure 2 As shown, Figure 2 The results of the five-cycle measurement are averaged. As can be seen from the figure, the mixture of dichloromethane and water has the largest flux, which is 141442.3±451 L·m -2 ·h -1 The mixture of cyclohexane and water has the smallest flux, which is 38102.1±2126 L·m-2 ·h -1 .

[0056] 2.2. Measuring separation efficiency

[0057] The separation efficiency (η) of the oil-water mixture is obtained by comparing the volume of water collected after oil-water separation (V0) with the volume of water in the initial oil-water mixture (V1). The calculation formula is as follows: η = V0 / V1 × 100%. The volume of water obtained after oil-water separation in 2.1 is measured and the results are shown in Figure 2 (The average value is taken after 5 cycles of measurement). As can be seen from the figure, the oil-water separation material CNBA / CF prepared in Example 1 can achieve a separation efficiency of more than 97% for a mixture of dichloromethane, chloroform, cyclohexane, toluene, petroleum ether, n-heptane and water.

[0058] 3. Test the adsorption capacity of CNBA / CF on different oily substances

[0059] The CNBA / CF prepared in Example 1 was weighed with a mass of m0 and immersed in an oil-water mixture until it reached saturation with the target liquid. The mixture was quickly removed and its mass m1 was measured to prevent evaporation of the absorbed liquid and affect the measurement results. The oil-water mixtures were: a mixture of polydimethylsiloxane (PDMS) and water in a volume ratio of 1:1, a mixture of ethyl acetate and water in a volume ratio of 1:1, a mixture of petroleum ether and water in a volume ratio of 1:1, a mixture of dichloromethane (DCM) and water in a volume ratio of 1:1, a mixture of chloroform and water in a volume ratio of 1:1, a mixture of n-hexane and water in a volume ratio of 1:1, a mixture of cyclohexane and water in a volume ratio of 1:1, and a mixture of toluene and water in a volume ratio of 1:1.

[0060] Evaluation of the adsorption capacity and saturation adsorption time of various oils, mass absorption capacity (Q m / m ) and volume absorption capacity (Q v / v ) are calculated according to the following formula: Q m / m =(m1-m0) / m0, Q V / V =Q m / m ×d s / d l ; Among them, d s is the bulk density of the oil-water separation material, d l is the density of the adsorbed liquid. The mass absorption capacity is calculated as Figure 3 The volume absorption capacity calculation results are shown as Figure 4 As shown. Figure 3 It can be seen from the above that CNBA / CF has several times or even more than ten times the mass absorption capacity of various oils; Figure 4 It can be seen that the micropore space of CNBA / CF is filled with various oils, and due to its viscosity relationship with the oil phase, CNBA / CF has a volume adsorption capacity close to or even exceeding 100% for various oils.

[0061] 4. Determine the effect of oil-water separation material thickness on oil flux and separation efficiency

[0062] Graphite carbon felts with an area of ​​2 cm × 2 cm and thicknesses of 0.8 cm, 0.5 cm, 0.4 cm, 0.3 cm, and 0.2 cm were prepared according to the method in Example 1 to prepare oil-water separation materials CNBA / CF of different thicknesses. These materials were then used to separate a mixture of dichloromethane and water (volume ratio of 1:1). The oil flux and separation efficiency were calculated according to the formula in item 2. The results are shown in FIG. Figure 5 As shown. Figure 5 It can be seen that the thinner the material, the greater the oil flux; the oil flux of CNBA / CF with a thickness of 0.2 cm is the largest, reaching 429333.2±13577 L·m -2 ·h -1 ; However, the separation efficiency is not affected by the thickness of the material and can reach more than 97%.

[0063] 5. Determine the stability of oil-water separation materials

[0064] The composite material CNBA / CF prepared in Example 1 was used to separate a dichloromethane / water mixture (volume ratio of 1:1) to test the flux and separation efficiency. The test was repeated 55 times, 10 of which were for the separation of a petroleum ether / water mixture (volume ratio of 5:1). The test results are shown in FIG. Figure 6 As shown. Figure 6 It can be seen that the test results are close to those in item 2, the separation efficiency remains above 97%, and the water contact angle does not change much before and after the measurement, indicating that the performance of the material is stable and can be recycled many times.

[0065] The composite material CNBA / CF prepared in Example 1 was used to conduct tests under more stringent conditions. The specific method is as follows:

[0066] The composite material CNBA / CF was immersed in boiling water for 24 hours, or immersed in 1M hydrochloric acid (HCl), 3M KCl solution, 0.1M NaOH solution, toluene, and dichloromethane (DCM) for 12 hours each. After washing with appropriate amounts of ethanol and deionized water, the treated oil-water separation material was dried in a 60°C oven. The oil-water separation material treated under various conditions was used to separate a dichloromethane / water mixture (volume ratio of 1:1). The average value of the measured results was obtained after 5 cycles. Figure 7 As shown. Figure 7 It can be seen that the oil flux of the test did not decrease, and the separation efficiency remained above 97%, indicating that the chemical structure and performance of the material are very stable, and it has excellent characteristics of acid and alkali corrosion resistance, high temperature resistance, and salt resistance.

[0067] 6. Determination of the self-purification ability of oil-water separation materials

[0068] The composite material CNBA / CF prepared in Example 1 was used to photodegrade an aqueous solution of Bengal Rose Red (RB). First, a 2 cm × 2 cm × 0.5 cm composite material CNBA / CF was placed in 30 mL of RB aqueous solution (0.02 mg / mL) and immersed in the dark for 30 minutes to reach adsorption equilibrium. Next, the system was exposed to a xenon lamp with a light source of 1000 w / m 2 The concentration of RB aqueous solution was monitored every 20 minutes by UV-visible spectrophotometer. Figure 8 、 9 As shown in the figure, it can be seen that after the material is placed in RB aqueous solution and treated with light, the RB concentration decreases significantly, which shows that the oil-water separation material prepared in Example 1 can effectively degrade organic matter in the aqueous solution under the catalysis of visible light in the liquid phase.

[0069] The composite material CNBA / CF prepared in Example 1 was used to photodegrade the adsorbed RB in air. First, CNBA / CF was immersed in a RB solution (0.1 mg / mL, dissolved in ethanol) for 5 minutes to absorb the RB dye on the CNBA / CF. After drying, the RB dye was absorbed under a xenon lamp light source of 1000 w / m 2 A batch of CNBA / CF samples of the same size, each containing RB, were irradiated at a power of 100 nm. After every 30 minutes, one of these samples was shaken in 2 mL of anhydrous ethanol for 30 minutes to elute the remaining adsorbed RB molecules and obtain an RB elution solution. The concentration of the obtained RB elution solution was then measured by UV-visible spectrophotometry, as shown in the following figure: Figure 8 、 10As shown in the figure, it can be seen that the amount of RB on the material is significantly reduced after photocatalysis, which shows that the oil-water separation material prepared in Example 1 can effectively degrade organic matter adsorbed on the material under visible light catalysis in an air atmosphere.

[0070] It should be noted that, in addition to the above-mentioned melamine, urea, and dicyandiamide as preferred carbon nitride precursors in the technical solution of the present invention, cyanamide can also be used in the technical solution of the present invention as a preferred carbon nitride precursor. In addition to benzyl alcohol, phenylethyl alcohol, and phenol as preferred surface modification materials in the technical solution of the present invention, n-heptanol and n-octanol can also be used in the technical solution of the present invention as preferred surface modification materials. When cyanamide, n-heptanol, and n-octanol not listed in the above embodiments are used in the technical solution of the present invention, the oil-water separation material is prepared with reference to the preparation method of the oil-water separation material in Example 1, and the technical effect is measured with reference to the method in Example 4. The results obtained are substantially the same as those in Example 1, and thus are not described in detail.

[0071] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It will be apparent to anyone skilled in the art that various modifications and variations of the present invention are possible. Any simple equivalent variations and modifications made in accordance with the scope of protection of the present invention and the contents of the specification are intended to be included within the scope of protection of the present invention.

Claims

1. A method for preparing an oil-water separation material with photocatalytic self-purification capability, characterized in that: The following steps are involved: S1. reacting a carbon nitride precursor with a carbon fiber material under heating conditions to prepare a CN / CF material in which carbon nitride is coated on the surface of the carbon fiber; the mass ratio of the carbon nitride precursor to the carbon fiber material is 1:(1.5-2.0); S2. In an inert gas atmosphere, reacting the surface modification material with the CN / CF material at 200° C. to 350° C. for 1 to 2 hours to obtain the oil-water separation material; The surface modification material is at least one of benzyl alcohol, phenylethyl alcohol, phenol, n-heptanol, and n-octanol; the mass ratio of the surface modification material to the CN / CF material is (0.5~1):

1.

2. The preparation method according to claim 1, characterized in that The carbon nitride precursor is at least one of melamine, urea, cyanamide and dicyandiamide.

3. The preparation method according to claim 1, characterized in that The carbon fiber material includes at least one of graphite carbon felt, carbon paper, and carbon nanotubes.

4. The preparation method according to claim 3, characterized in that The carbon fiber material is graphite carbon felt with a thickness of 0.2 to 0.8 cm.

5. The preparation method according to claim 1, characterized in that The reaction under heating conditions in step S1 refers to the reaction at 450° C. to 600° C. for 2 to 4 hours.

6. The preparation method according to claim 5, characterized in that The heating rate in step S1 is 2.5°C to 5.0°C / min; or / and the heating rate in step S2 is 5.0°C to 10.0°C / min.

7. An oil-water separation material having photocatalytic self-purification capability prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the oil-water separation material with photocatalytic self-purification capability prepared by the preparation method according to any one of claims 1 to 6 in the field of oil-water separation or / and in visible light catalytic degradation of organic pollutants in wastewater.

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