Submerged super-amphiphobic oil-water separation material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oil-water mixture separation materials, and particularly relates to a submerged super-amphiphobic oil-water separation material as well as a preparation method and application thereof. The preparation method of the submerged super-amphiphobic oil-water separation material comprises the following steps: (1) carrying out photoresist removal, acidification and vacuum plasma pretreatment on carbon fibers; (2) growing Co (OH) 2 nanocrystals on the surfaces of the pretreated carbon fibers in a coating manner, and carrying out calcination treatment to convert Co (OH) 2 into Co3O4; and (3) converting Co3O4 on the surface of the carbon fiber obtained in the step (2) into CoS2 in situ under the action of a vulcanizing agent to obtain the submerged super-amphiphobic oil-water separation material. The method has the beneficial effects that the material prepared by the method has excellent submerged super-amphiphobic property, shows super-oleophobicity underwater and super-hydrophobicity under oil, can efficiently separate light oil / water and heavy oil / water mixtures, and has the separation efficiency of 90% or above. The method has a wide application prospect in the field of complex oil-water separation.

Description

Technical Field

[0001] This application belongs to the technical field of oil-water mixture separation materials, specifically relating to a superhydrophobic oleophobic material for liquid separation, its preparation method, and its application. Background Technology

[0002] With the booming development of industrial production, the discharge of oily wastewater has increased dramatically, and oil spills have occurred frequently, posing a serious threat to the ecological environment and human health. Faced with the challenge of treating oily wastewater, numerous technologies have emerged, with membrane separation technology gaining popularity in the field of oil-water separation due to its advantages such as high efficiency, low energy consumption, and ease of operation. However, the separation materials used in current membrane separation technologies are mostly single-functional. For example, superhydrophilic-superoleophobic "water removal" membranes are only suitable for separating light oil / water mixtures, while superoleophilic-superhydrophobic "oil removal" membranes can only handle heavy oil / water systems, making them difficult to apply in complex oil-water separation environments. To address this, researchers have proposed the concept of "subsurface superhydrophobicity," which achieves "on-demand separation" by making the material superoleophobic underwater and superhydrophobic underwater, using pre-wetting control. However, most of the reported superhydrophobic materials for liquid environments are modified with fluorine-containing compounds or rely on external stimuli (such as temperature, pH, light) to obtain superhydrophobic properties, resulting in high cost, poor environmental compatibility, harsh response conditions, and poor mechanical stability and cycling performance, making it difficult to apply them in complex oil-water separation environments. Summary of the Invention

[0003] This application provides a superhydrophobic oleophobic material for underwater separation, its preparation method, and its application. It aims to solve the problems of complex preparation process, high cost, and poor stability of existing superhydrophobic materials for underwater separation, so as to achieve efficient and stable separation of oily wastewater.

[0004] The first aspect of this application provides a method for preparing a liquid-based superhydrophilic water-separating material, comprising the following steps: (1) The carbon fiber is subjected to degumming, acidification and vacuum plasma pretreatment; (2) Co(OH)2 nanocrystals were grown on the surface of the pretreated carbon fiber and then calcined to convert Co(OH)2 into Co3O4. (3) Under the action of the vulcanizing agent, the Co3O4 on the surface of the carbon fiber obtained in step (2) is converted into CoS2 in situ to obtain the liquid super oleophobic water separation material.

[0005] According to some embodiments of the preparation method of the liquid superhydrophobic water separation material described in this application, in step (1), the degumming process includes: immersing the carbon fiber in acetone, and after immersion, drying it.

[0006] According to some embodiments of the preparation method of the superhydrophobic underwater separation material described in this application, the carbon fiber is immersed in acetone at a temperature of 20-30°C for 1-4 hours.

[0007] According to some embodiments of the preparation method of the underwater superbihydrophobic water separation material described in this application, the drying temperature is 20-100℃ and the drying time is 1-8h.

[0008] According to some embodiments of the preparation method of the liquid-based super oleophobic water-separating material described in this application, the acidification treatment step includes: immersing the degummed carbon fiber in concentrated nitric acid, and after immersion, washing it with water until neutral and drying it; as a preferred embodiment, the immersion temperature of the carbon fiber in concentrated nitric acid is 20-30℃, and the immersion time is 3-7h.

[0009] According to some embodiments of the preparation method of the submersible superbihydrophobic water separation material described in this application, the drying temperature is 20-100℃ and the drying time is 1-8h.

[0010] According to some embodiments of the preparation method of the underwater super oleophobic water separation material described in this application, the mass concentration of the concentrated nitric acid is 60%-68%.

[0011] According to some embodiments of the preparation method of the underwater superhydrophilic water separation material described in this application, the vacuum degree of the vacuum plasma treatment is 10-60 Pa, the power of the vacuum plasma treatment is 50-300 W, and the duration of the vacuum plasma treatment is 5-30 min.

[0012] According to some embodiments of the preparation method of the liquid superhydrophobic water separation material described in this application, step (2) of coating and growing Co(OH)2 nanocrystals on the surface of the pretreated carbon fiber includes the following steps: contacting the carbon fiber and the cobalt salt reaction solution for reaction, and after the reaction is completed, washing the reaction product with water and ethanol in sequence, and drying.

[0013] According to some embodiments of the preparation method of the liquid-based super oleophobic water-separating material described in this application, the cobalt salt reaction solution includes cobalt salt, alkali source, morphology modifier and water.

[0014] According to some embodiments of the preparation method of the liquid-based superhydrophobic water separation material described in this application, the cobalt salt includes one or more of cobalt nitrate, cobalt chloride, cobalt sulfate, and cobalt acetate; According to some embodiments of the preparation method of the liquid-based superhydrophobic water separation material described in this application, the alkaline source includes one or more of urea, ammonia, and hexamethylenetetramine. According to some embodiments of the preparation method of the underwater superbihydrophobic water separation material described in this application, the morphology control agent includes ammonium fluoride and / or ammonium hydrogen fluoride.

[0015] According to some embodiments of the preparation method of the liquid-based superhydrophobic water separation material described in this application, the molar ratio of cobalt salt, alkali source, morphology modifier and water in the cobalt salt reaction solution is 1:(2-10):(2.5-10):(278-1111).

[0016] According to some embodiments of the preparation method of the liquid-based super oleophobic water-separating material described in this application, the contact reaction temperature of the carbon fiber and cobalt salt reaction solution is 90-150℃, and the contact reaction time is 6-12h.

[0017] According to some embodiments of the preparation method of the superhydrophobic oleophobic water separation material described in this application, in step (2), the calcination temperature is 300-400℃ and the calcination time is 1-6h.

[0018] According to some embodiments of the preparation method of the underwater superbihydrophobic water separation material described in this application, the heating rate during the calcination process is 2-10℃ / min.

[0019] According to some embodiments of the preparation method of the underwater superbihydrophobic water separation material described in this application, the calcination atmosphere is air or oxygen.

[0020] According to some embodiments of the preparation method of the superhydrophobic water-separating material under liquid as described in this application, in step (3), the sulfiding agent includes one or more of sodium sulfide, sodium hydrosulfide, ammonium sulfide, thiourea and thioacetamide.

[0021] According to some embodiments of the preparation method of the superhydrophobic water-separating material under liquid described in this application, the step (3) of converting Co3O4 on the surface of carbon fiber into CoS2 includes: contacting the carbon fiber obtained in step (2) with the vulcanizing agent solution to carry out a vulcanization reaction.

[0022] According to some embodiments of the preparation method of the underwater superbihydrophobic water separation material described in this application, the concentration of the sulfiding agent solution is 0.05-0.5 mol / L.

[0023] According to some embodiments of the preparation method of the underwater superhydrophilic water-separating material described in this application, the mass ratio of the carbon fiber to the vulcanizing agent is 1:0.8-5.6.

[0024] According to some embodiments of the preparation method of the underwater superbihydrophobic water separation material described in this application, the temperature of the sulfidation reaction is 120-200℃, and the time of the sulfidation reaction is 10-24h.

[0025] The second aspect of this application provides a submersible superbihydrophobic water separation material, which is prepared by the preparation method described in the first aspect of this application.

[0026] Applications of the superhydrophobic oleophobic water separator material obtained by the preparation method described in the first aspect of this application or the superhydrophobic oleophobic water separator material described in the second aspect of this application in the treatment of oily wastewater and oil spills.

[0027] The beneficial effects of this application include: (1) This application uses hydrothermal, calcination and sulfidation processes to prepare CoS2 / Co3O4@CF liquid superbihydrophobic water separation material. The process is simple and controllable, and does not require expensive chemical reagents or complex equipment, thus reducing the preparation cost.

[0028] (2) In this application, carbon fiber with excellent corrosion resistance and high chemical stability is selected as the substrate, and a CoS2 composite structure is constructed on the Co3O4@CF surface by in-situ vulcanization. Among them, Co3O4 can achieve a stable connection with the carbon fiber substrate, thereby providing a precursor coating with good bonding force for the composite structure, ensuring that the material has good durability and cycle stability in long-term continuous separation experiments.

[0029] (3) The superhydrophobic oleophobic water separation material prepared in this application exhibits superoleophobicity underwater and superhydrophobicity in oil. The two states can be reversibly switched by simple pre-wetting, and the material still maintains good underwater double hydrophobic properties after multiple cycles. This breaks through the limitation that a single wettability material can only separate a single type of oil-water mixture. It has high separation flux and efficiency for both light oil / water and heavy oil / water mixtures (separation efficiency is above 90%). Attached Figure Description

[0030] Figure 1 The XRD pattern of the submersible superhydrophobic water separation material prepared in Example 1 of this application is shown. Figure 2 XPS spectrum of the submersible superhydrophobic water separation material prepared in Example 1 of this application; Figure 3 This is a scanning electron microscope image of the underwater superhydrophilic water-separating material prepared in Example 1 of this application; Figure 4 The wettability test diagrams (in air, underwater, and in oil) of the liquid-borne superbihydrophobic water-separating material prepared in Example 1 of this application are shown. Figure 5 This is a diagram showing the separation flux of different types of oil-water mixtures by the submersible superbihydrophobic water separator prepared in Example 1 of this application. Detailed Implementation

[0031] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0033] This application provides a method for preparing a submersible superhydrophilic water-separating material, including the following steps: (1) The carbon fiber is subjected to degumming, acidification and vacuum plasma pretreatment; (2) Co(OH)2 nanocrystals were grown on the surface of the pretreated carbon fiber and then calcined to convert Co(OH)2 into Co3O4. (3) Under the action of the vulcanizing agent, the Co3O4 on the surface of the carbon fiber obtained in step (2) is converted into CoS2 in situ to obtain the liquid super oleophobic water separation material.

[0034] This application first involves degumming, acidification, and vacuum plasma treatment of carbon fibers. Then, a Co(OH)₂ nanoneedle array is grown on the carbon fiber surface using a hydrothermal method combined with calcination, which is then converted into Co₃O₄@CF. Finally, in-situ vulcanization is used to convert Co₃O₄ into CoS₂, constructing a CoS₂ / Co₃O₄@CF underwater superbihydrophobic water-separating material. The Co₃O₄ precursor prepared by this material endows the functional coating with good adhesion and a rough, nanoneedle-like structure, while the surface energy of the in-situ vulcanized CoS₂ lies between that of water and oil. Under the synergistic effect of this rough structure and surface energy, the material adsorbs water molecules underwater to form a water film, thus becoming superoleophobic, and adsorbs oil molecules underwater to form an oil film, thus becoming superhydrophobic. Pre-wetting control allows for "on-demand separation" of light oil / water and heavy oil / water mixtures.

[0035] The material described in this application has high separation throughput and separation efficiency, and exhibits good separation effect in the separation of complex oil-water systems (oil-water mixtures such as gasoline / water and petroleum ether / water). It is expected to be widely used in fields such as industrial oily wastewater treatment and emergency response to oil spills.

[0036] In some embodiments of this application, step (1) includes: immersing the carbon fiber in acetone, and drying it after immersion.

[0037] In some embodiments of this application, the carbon fiber is immersed in acetone at a temperature of 20-30°C, such as 20°C, 25°C, 30°C, etc., and the immersion time is 1-4 hours.

[0038] In some embodiments of this application, the drying temperature is 20-100℃, such as 20℃, 30℃, 50℃, 80℃, 100℃, etc., and the drying time is 1-8h, such as 1h, 3h, 5h, 8h, etc.

[0039] In some embodiments of this application, the acidification treatment step includes: immersing the degummed carbon fiber in concentrated nitric acid, and after immersion, rinsing with water until neutral, and drying; as a preferred embodiment, the immersion temperature of the carbon fiber in concentrated nitric acid is 20-30℃, and the immersion time is 3-7 hours; as a preferred embodiment, the drying temperature is 20-100℃, and the drying time is 1-8 hours; as a preferred embodiment, the mass concentration of the concentrated nitric acid is 60%-68%; for example, 60%, 63%, 65%, 68%, etc.

[0040] In some embodiments of this application, the vacuum degree of the vacuum plasma treatment is 10-60 Pa, such as 10 Pa, 20 Pa, 30 Pa, 40 Pa, 50 Pa, 60 Pa, etc., the power of the vacuum plasma treatment is 50-300 W, such as 50 W, 80 W, 100 W, 120 W, 150 W, 210 W, 230 W, 300 W, etc., and the duration of the vacuum plasma treatment is 5-30 min, such as 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, etc.

[0041] In some embodiments of this application, step (2) of coating and growing Co(OH)2 nanocrystals on the surface of the pretreated carbon fiber includes the following steps: contacting the carbon fiber and the cobalt salt reaction solution for reaction, and after the reaction is completed, washing the reaction product with water and ethanol in sequence, and drying.

[0042] In some embodiments of this application, the cobalt salt reaction solution includes cobalt salt, alkali source, morphology modifier and water.

[0043] In some embodiments of this application, the cobalt salt includes one or more of cobalt nitrate, cobalt chloride, cobalt sulfate, and cobalt acetate.

[0044] In some embodiments of this application, the alkaline source includes one or more of urea, ammonia, and hexamethylenetetramine.

[0045] In some embodiments of this application, the morphology modifier includes ammonium fluoride and / or ammonium hydrogen fluoride.

[0046] In some embodiments of this application, the molar ratio of cobalt salt, alkali source, morphology modifier and water in the cobalt salt reaction solution is 1:(2-10):(2.5-10):(278-1111).

[0047] In some embodiments of this application, the contact reaction temperature between the carbon fiber and the cobalt salt reaction solution is 90-150°C, such as 90°C, 98°C, 115°C, 125°C, 136°C, 150°C, etc., and the contact reaction time is 6-12h, such as 6h, 8h, 10h, 12h, etc.

[0048] In some embodiments of this application, in step (2), the calcination temperature is 300-400℃, such as 300℃, 320℃, 360℃, 380℃, 400℃, etc., and the calcination time is 1-6h, such as 1h, 2h, 4h, 6h, etc.

[0049] In some embodiments of this application, the heating rate during the calcination process is 2-10℃ / min; for example, 2℃ / min, 5℃ / min, 7℃ / min, 10℃ / min, etc.

[0050] In some embodiments of this application, the calcination atmosphere is air or oxygen.

[0051] In some embodiments of this application, in step (3), the vulcanizing agent includes one or more of sodium sulfide, sodium hydrosulfide, ammonium sulfide, thiourea, and thioacetamide.

[0052] In some embodiments of this application, step (3) of converting Co3O4 on the surface of carbon fiber into CoS2 includes: contacting the carbon fiber obtained in step (2) with a vulcanizing agent solution to carry out a vulcanization reaction.

[0053] In some embodiments of this application, the concentration of the vulcanizing agent solution is 0.05-0.5 mol / L; for example, 0.05 mol / L, 0.12 mol / L, 0.26 mol / L, 0.38 mol / L, 0.46 mol / L, 0.5 mol / L, etc.

[0054] In some embodiments of this application, the mass ratio of the carbon fiber to the vulcanizing agent is 1:0.8-5.6, for example, 1:0.8, 1:1.2, 1:2.6, 1:3.3, 1:4.1, 1:5, 1:5.6, etc.

[0055] In some embodiments of this application, the temperature of the vulcanization reaction is 120-200℃, such as 120℃, 150℃, 180℃, 200℃, etc., and the time of the vulcanization reaction is 10-24h, such as 10h, 15h, 18h, 20h, 24h, etc.

[0056] This application also provides a liquid-based superaqueous oleophobic water-separating material, prepared by the method described in the first aspect of this application. The liquid-based superaqueous oleophobic water-separating material described in this application (denoted as CoS2 / Co3O4@CF) exhibits superamphilicity in air, meaning both the water contact angle and the oil contact angle are 0°. When CoS2 / Co3O4@CF is immersed in petroleum ether or water, water droplets stained with methylene blue and oil droplets stained with Sudan III both exhibit spherical shapes on its surface. Furthermore, when the surface of CoS2 / Co3O4@CF is pre-wetted with a liquid phase (aqueous or oily), the first wetting phase is firmly locked within the micropores of CoS2 / Co3O4@CF, thus preventing it from being replaced by the second phase upon immersion. This unique wetting behavior provides an important foundation for the application of CoS2 / Co3O4@CF in the field of oil-water separation.

[0057] This application also provides an application of the underwater super-ampholy oleophobic water separator material prepared by the preparation method described in the first aspect of this application, or the underwater super-ampholy oleophobic water separator material described in the second aspect of this application, in the treatment of oily wastewater and the handling of oil spills. The technical solution of this application will be further described below with reference to specific embodiments.

[0058] Example 1 A method for preparing a liquid-based superaqueous oleophobic water-separating material includes the following steps: Step 1: Perform degumming, acidification, and vacuum plasma pretreatment on the carbon fiber. Step 1.1: Immerse the carbon fiber completely in acetone solution at 25°C for 1 hour, then remove it and dry it in an oven at 20°C for 8 hours. Step 1.2: The carbon fiber treated in step 1.1 is placed in a concentrated nitric acid solution with a mass concentration of 68% and soaked at 25°C for 3 hours. After being taken out, it is washed with distilled water until the aqueous solution is neutral and dried at 20°C for 8 hours. Step 1.3 involves subjecting the carbon fiber surface treated in step 1.2 to vacuum plasma treatment; wherein the vacuum degree of the vacuum plasma treatment is 10 Pa, the plasma power is 50 W, and the treatment time is 30 min.

[0059] Step 2: Co(OH)2 nanocrystals are grown on the surface of carbon fibers. Step 2.1 Weigh 2 mmol of cobalt nitrate and dissolve it in 40 ml of deionized water. Add 5 mmol of ammonium fluoride and 4 mmol of urea to the solution and stir for 30 min until a clear purple solution is obtained. This is the hydrothermal cobalt salt reaction solution. The molar ratio of cobalt nitrate: urea: ammonium fluoride: deionized water is 1: 2:2.5:1111. Step 2.2 Immerse the carbon fiber pretreated in Step 1 into a hydrothermal reactor containing the cobalt salt reaction solution from Step 2.1 (the mass ratio of carbon fiber to cobalt salt reaction solution is 1:414) and set the hydrothermal temperature to 120℃ for 10 hours. Step 2.3 After the reaction is complete, the sample is taken out and rinsed four times with deionized water and anhydrous ethanol in sequence. The washed sample is then dried in a 70℃ drying oven for 6 hours to obtain Co(OH)2 nanocrystals.

[0060] Step 3: Place the Co(OH)2 nanocrystals obtained in Step 2.3 into a muffle furnace, heat to 300℃ at a heating rate of 2℃ / min in air atmosphere and hold for 6h. After natural cooling, the precursor material is obtained, denoted as Co3O4@CF.

[0061] Step 4.1 Weigh 0.552g of sodium sulfide and dissolve it in 60ml of deionized water. Stir magnetically for 30min to make the solution uniform. Prepare a sulfidation reaction solution with a concentration of 0.118mol / L. Immerse Co3O4@CF in the prepared sulfidation reaction solution (the mass ratio of Co3O4@CF to sulfiding agent is 1:2.76). Then transfer it to a hydrothermal reactor at 120℃ for sulfidation reaction for 22h. Step 4.2 After the reaction is complete, cool the furnace to room temperature to obtain the underwater superaphthobic oleophobic water separation material, denoted as CoS2 / Co3O4@CF.

[0062] The XRD pattern of the liquid-based superaqueous oleophobic water-separating material (CoS2 / Co3O4@CF) prepared in Example 1 is shown below. Figure 1 As shown. From Figure 1It can be seen that the peaks at 31.31°, 36.81°, 44.81°, 59.31°, and 65.21° belong to the (220), (311), (400), (511), and (440) crystal planes of Co3O4 (JCPDS No. 42-1467), while the diffraction peaks at 32.31°, 36.31°, and 55.51° belong to the (200), (210), and (311) crystal planes of CoS2 (JCPDS No. 70-2865), respectively. After sulfidation, the intensity of the diffraction peaks of Co3O4 is significantly reduced, indicating that the surface Co3O4 is transformed into CoS2 during the sulfidation process. In addition, no other impurity peaks were observed in the XRD pattern, indicating that the prepared CoS2 / Co3O4@CF has high purity, and both CoS2 and Co3O4 exist in a highly crystalline form. Furthermore, the peaks at Co 2p, O 1s, and S are also observed. A detailed analysis of the 2p high-resolution spectrum was conducted, confirming the successful construction of the CoS2 / Co3O4 material.

[0063] XPS spectra and scanning electron microscope images of the liquid-based superaqueous oleophobic water-separating material (CoS2 / Co3O4@CF) prepared in Example 1 are shown below. Figure 2 and Figure 3 As shown.

[0064] from Figure 2 It can be seen that C, O, Co, and S elements were detected on the CoS2 / Co3O4@CF surface; in the scanning electron microscope images, Figure 3 (among them, Figure 3 a- Figure 3 c shows the microstructure of the underwater superbihydrophobic water separation material at magnifications of 4μm, 2μm, and 1μm, respectively. As the magnification increases, it can be seen that the carbon fiber surface is densely coated with CoS2 / Co3O4 nanosheets.

[0065] The wettability test diagrams (in air, underwater, and in oil) of the liquid-borne superbihydrophobic water-separating material (CoS2 / Co3O4@CF) prepared in Example 1 are shown below. Figure 4 As shown.

[0066] Figure 4 'a' represents the contact angle of the submersible superbihydrophobic water separator material described in this embodiment with trichloroethylene in water and with water in petroleum ether.

[0067] Figure 4 b is a test diagram of the oil-water separation performance of the submersible superbihydrophobic material described in this embodiment.

[0068] from Figure 4 a and Figure 4As shown in b, when the CoS2 / Co3O4@CF material is immersed in water, the contact angle of trichloroethylene oil droplets on its surface in the water reaches 163.8°; when the CoS2 / Co3O4@CF is immersed in petroleum ether, the contact angle of water droplets on its surface in the petroleum ether is 162.3°, both contact angles being higher than 150°. This indicates that CoS2 / Co3O4@CF possesses both underwater superoleophobicity and oil-based superhydrophobicity.

[0069] Using a chromatography column as the oil-water separation device, and the CoS2 / Co3O4@CF underwater superhydrophobic material prepared in Example 1 as the separation membrane, a receiving container for the oil phase was placed at the bottom of the chromatography column. Water and chlorobenzene (volume ratio 1:1) were thoroughly mixed to prepare a water-chlorobenzene oil-water mixture. The CoS2 / Co3O4@CF underwater superhydrophobic material separation membrane prepared in Example 1 was pre-wetted with gasoline and then loaded into the chromatography column, followed by the water-chlorobenzene oil-water mixture. The results showed that chlorobenzene flowed out from the bottom of the chromatography column through the CoS2 / Co3O4@CF underwater superhydrophobic material, while water was blocked above the material, thus achieving oil-water separation. After 1 hour of continuous oil-water separation, the separation flux for chlorobenzene was 13056.3 L•m. -2 •h -1 The separation efficiency is 98.1% (e.g., Figure 5 As shown in the figure, it exhibits excellent oil-water separation performance; after 48 hours of use, the separation flux is 12391.73 L•m. -2 •h -1 The decrease was only 5.09%, indicating that the material has good durability and stability in continuous separation experiments.

[0070] Example 2 A method for preparing a liquid-based superaqueous oleophobic water-separating material includes the following steps: Step 1: Perform degumming, acidification, and vacuum plasma pretreatment on the carbon fiber. Step 1.1: Immerse the carbon fiber completely in acetone solution and soak at 25°C for 2 hours. After soaking, place it in an oven at 50°C for 6 hours to dry. Step 1.2: The carbon fiber treated in step 1.1 is placed in a 60% concentrated nitric acid solution and soaked at 25°C for 4 hours. After being removed, it is washed with distilled water until the aqueous solution is neutral and dried at 50°C for 6 hours. Step 1.3 involves subjecting the carbon fiber surface treated in Step 1.2 to vacuum plasma treatment. The vacuum level is 20 Pa, the plasma power is 150 W, and the treatment time is 25 min.

[0071] Step 2.1 Weigh 6 mmol of cobalt chloride and dissolve it in 40 ml of deionized water. Add 37.5 mmol of ammonium bifluoride and 18 mmol of ammonia to the solution and stir for 30 min until a clear purple solution is obtained. This is the hydrothermal cobalt salt reaction solution. The molar ratio of cobalt chloride, ammonia, ammonium bifluoride and deionized water is 1:6:6.5:370. Step 2.2 Immerse the carbon fibers pretreated in Step 1 into a hydrothermal reactor containing the cobalt salt reaction solution (the mass ratio of carbon fibers to cobalt salt reaction solution is 1:403) and set the hydrothermal temperature to 90°C for 12 hours.

[0072] Step 2.3 After the reaction is complete, the sample is taken out and rinsed three times with deionized water and anhydrous ethanol in sequence. The washed sample is then dried in a 60℃ drying oven for 12 hours to obtain Co(OH)2 nanocrystals.

[0073] Step 3: Place the Co(OH)2 nanocrystals obtained in Step 2.3 into a muffle furnace, heat to 350℃ at a heating rate of 5℃ / min under an oxygen atmosphere and hold for 4h. After natural cooling, the precursor material is obtained, denoted as Co3O4@CF.

[0074] Step 4.1 Weigh 0.168g of sodium hydrosulfide and dissolve it in 60ml of deionized water. Stir magnetically for 30min to make the solution uniform and prepare a sulfidation reaction solution with a concentration of 0.05mol / L. Immerse Co3O4@CF into the prepared sulfidation reaction solution (the mass ratio of Co3O4@CF to sulfiding agent is 1:0.8). Then transfer it to a hydrothermal reactor at 130℃ for sulfidation reaction for 18h. Step 4.2 After the reaction is complete, cool the furnace to room temperature to obtain the underwater superaphthobic oleophobic water separation material, denoted as CoS2 / Co3O4@CF.

[0075] The CoS2 / Co3O4@CF prepared in this embodiment has a contact angle of 164.5° with carbon tetrachloride in water and a contact angle of 163.2° with water in n-hexane, indicating that CoS2 / Co3O4@CF possesses both underwater superoleophobicity and oil-water superhydrophobicity.

[0076] A water-trichloroethylene oil-water mixture was prepared by thoroughly mixing water and trichloroethylene (volume ratio 1:1). The oil-water separation performance was tested using a chromatography column as the oil-water separation device and the CoS2 / Co3O4@CF submerged superhydrophobic material prepared in this embodiment as the separation membrane. First, the CoS2 / Co3O4@CF was pre-wetted with trichloroethylene and then packed into the chromatography column, followed by the water-trichloroethylene oil-water mixture. The results showed that trichloroethylene flowed out from the bottom of the chromatography column through the CoS2 / Co3O4@CF submerged superhydrophobic material, while water was blocked above the CoS2 / Co3O4@CF submerged superhydrophobic membrane, thus achieving oil-water separation. The average separation flux of trichloroethylene after 1 hour of continuous oil-water separation was 15536.1 L•m. -2 •h -1 The separation efficiency is 98.6% (e.g., Figure 5 As shown in the figure, it exhibits excellent oil-water separation performance; after 48 hours of use, the separation flux is 14693.5 L•m. -2 •h -1 The decrease rate was only 5.42%, indicating that the membrane material has good durability and stability in continuous separation experiments.

[0077] Example 3 A method for preparing a liquid-based superaqueous oleophobic water-separating material includes the following steps: Step 1: Perform degumming, acidification, and vacuum plasma pretreatment on the carbon fiber. Step 1.1: Immerse the carbon fiber completely in acetone solution and soak at 25°C for 3 hours. After soaking, place it in an oven at 80°C for 3 hours to dry. Step 1.2: The carbon fiber treated in step 1.1 is placed in a concentrated nitric acid solution with a mass concentration of 64% and soaked at 25°C for 7 hours. After being taken out, it is washed with distilled water until the aqueous solution is neutral and dried at 80°C for 3 hours. Step 1.3: The carbon fiber surface treated in step 1.2 is subjected to vacuum plasma treatment; wherein the vacuum degree of vacuum plasma treatment is 40 Pa, the plasma power is 250 W, and the treatment time is 10 min.

[0078] Step 2.1 Weigh 4 mmol of cobalt sulfate and dissolve it in 40 mol of deionized water. Add 10 mmol of NH4F and 8 mmol of hexamethylenetetramine to the solution and stir for 30 min until a clear purple solution is obtained. This is the hydrothermal cobalt salt reaction solution. The molar ratio of cobalt sulfate, hexamethylenetetramine, ammonium fluoride, and deionized water is 1:8:2.5:556. Step 2.2 Immerse the carbon fibers pretreated in Step 1 into a hydrothermal reactor containing the above cobalt salt reaction solution (the mass ratio of carbon fibers to cobalt salt reaction solution is 1:430) and set the hydrothermal temperature to 130°C for 8 hours. Step 2.3 After the reaction is complete, the sample is taken out and rinsed four times with deionized water and anhydrous ethanol in sequence. The washed sample is then dried in an 80℃ drying oven for 10 hours to obtain Co(OH)2 nanocrystals.

[0079] Step 3: Place the Co(OH)2 nanocrystals obtained in Step 2.3 into a muffle furnace, heat to 370°C at a heating rate of 8°C / min in air atmosphere and hold for 3 hours. After natural cooling, the precursor material is obtained, denoted as Co3O4@CF.

[0080] Step 4.1 Weigh 1.224g of ammonium sulfide and dissolve it in 60ml of deionized water. Stir the solution magnetically for 30min to make it uniform and prepare a sulfidation reaction solution with a concentration of 0.3mol / L. Immerse Co3O4@CF into the prepared sulfidation reaction solution (the mass ratio of Co3O4@CF to sulfiding agent is 1:4). Then transfer it to a hydrothermal reactor at 140℃ for sulfidation reaction for 15h.

[0081] Step 4.2 After the reaction is complete, cool the furnace to room temperature to obtain the underwater superaphthobic oleophobic water separation material, denoted as CoS2 / Co3O4@CF.

[0082] The CoS2 / Co3O4@CF prepared in this embodiment has a contact angle of 164.5° with chloroform in water and a contact angle of 158.8° with water in cyclohexane, indicating that CoS2 / Co3O4@CF possesses both underwater superoleophobicity and oil-water superhydrophobicity.

[0083] A water-gasoline mixture was prepared by thoroughly mixing water and gasoline (volume ratio 1:1). The oil-water separation performance was tested using a chromatography column as the oil-water separation device and the CoS2 / Co3O4@CF subsurface superhydrophobic material prepared in this embodiment as the separation membrane. First, the CoS2 / Co3O4@CF was pre-wetted with water and then loaded into the chromatography column, followed by the water-gasoline mixture. The results showed that water flowed out from the bottom of the chromatography column through the CoS2 / Co3O4@CF subsurface superhydrophobic material, while gasoline was blocked above the CoS2 / Co3O4@CF subsurface superhydrophobic membrane, thus achieving oil-water separation. The average separation flux for water was 5637.6 L•m³ after 1 hour of continuous oil-water separation. -2 •h -1 The separation efficiency was 98.8%, demonstrating excellent oil-water separation performance; after 48 hours of use, the separation flux was 5288.9 L•m. -2 •h -1The decrease rate was only 6.19%, indicating that the membrane material has good durability and stability in continuous separation experiments.

[0084] Example 4 A method for preparing a liquid-based superaqueous oleophobic water-separating material includes the following steps: Step 1: Perform degumming, acidification, and vacuum plasma pretreatment on the carbon fiber. Step 1.1: Immerse the carbon fiber completely in acetone solution and soak at 25°C for 4 hours. After soaking, place it in an oven at 100°C for 1 hour to dry. Step 1.2: The carbon fiber treated in step 1.1 is placed in a concentrated nitric acid solution with a mass concentration of 66% and soaked at 25°C for 7 hours. After being taken out, it is washed with distilled water until the aqueous solution is neutral and dried at 100°C for 1 hour. Step 1.3 involves subjecting the carbon fiber surface treated in Step 1.2 to vacuum plasma treatment. The vacuum level of the vacuum plasma treatment is 60 Pa, the plasma power is 300 W, and the treatment time is 5 min.

[0085] Step 2.1 Weigh 8 mmol of cobalt acetate and dissolve it in 40 mol of deionized water. Add a mixture of 40 mmol of NH4F and 40 mmol of NH4HF2 and 80 mmol of urea to the solution and stir for 30 min until a clear purple solution is obtained. This is the hydrothermal cobalt salt reaction solution. The molar ratio of cobalt acetate, urea, morphology modifiers (ammonium fluoride and ammonium bifluoride), and deionized water is 1:10:10:278. Step 2.2 Immerse the carbon fibers pretreated in Step 1 into a hydrothermal reactor containing the above cobalt salt reaction solution (the mass ratio of carbon fibers to cobalt salt reaction solution is 1:425) and set the hydrothermal temperature to 140°C for 6 hours. Step 2.3 After the reaction is complete, the sample is taken out and rinsed 5 times with deionized water and anhydrous ethanol in sequence. The washed sample is then placed in a 90℃ drying oven and dried for 6 hours to obtain Co(OH)2 nanocrystals.

[0086] Step 3: Place the Co(OH)2 nanocrystals obtained in Step 2.3 in a muffle furnace, heat them to 400℃ at a heating rate of 10℃ / min under an oxygen atmosphere and hold for 2 hours. After natural cooling, the precursor material is obtained, denoted as Co3O4@CF.

[0087] Step 4.1 Weigh 2.25 g of thioacetamide and dissolve it in 60 ml of deionized water. Stir magnetically for 30 min to make the solution homogeneous and prepare a 0.5 mol / L sulfidation reaction solution. Immerse Co3O4@CF into the prepared sulfidation reaction solution (the mass ratio of Co3O4@CF to sulfiding agent is 1:5.6). Then transfer it to a hydrothermal reactor at 150℃ for sulfidation reaction for 10 h. Step 4.2 After the reaction is complete, cool the furnace to room temperature to obtain the underwater superaphthobic oleophobic water separation material, denoted as CoS2 / Co3O4@CF.

[0088] The CoS2 / Co3O4@CF prepared in this embodiment has a contact angle of 163.4° with dichloromethane in water and a contact angle of 162.5° with water in gasoline, indicating that CoS2 / Co3O4@CF possesses both underwater superoleophobicity and oil-water superhydrophobicity.

[0089] A water-cyclohexane oil-water mixture was prepared by thoroughly mixing water and cyclohexane (volume ratio 1:1). The oil-water separation performance was tested using a chromatography column as the oil-water separation device and the CoS2 / Co3O4@CF submerged superhydrophobic material obtained in this example as the separation membrane. First, the CoS2 / Co3O4@CF was pre-wetted with water and then packed into the chromatography column, followed by the water-cyclohexane oil-water mixture. The results showed that water flowed out from the bottom of the chromatography column through the CoS2 / Co3O4@CF submerged superhydrophobic material, while cyclohexane was blocked above the CoS2 / Co3O4@CF submerged superhydrophobic membrane, thus achieving oil-water separation. The average separation flux of water for 1 hour of continuous oil-water separation was 4485.3 L•m. -2 •h -1 The separation efficiency was 98.3%. Figure 5 It exhibits excellent oil-water separation performance; after 48 hours of use, the separation flux is 4282.1 L•m. -2 •h -1 The decrease rate was only 4.53%, indicating that the membrane material has good durability and stability in continuous oil-water separation experiments.

[0090] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for preparing a submersible superbihydrophobic water separation material, characterized in that, Includes the following steps: (1) The carbon fiber is subjected to degumming, acidification and vacuum plasma pretreatment; (2) Co(OH)2 nanocrystals were grown on the surface of the pretreated carbon fiber and then calcined to convert Co(OH)2 into Co3O4. (3) Under the action of the vulcanizing agent, the Co3O4 on the surface of the carbon fiber obtained in step (2) is converted into CoS2 in situ to obtain the liquid super oleophobic water separation material.

2. The preparation method of the underwater superbihydrophobic water separation material according to claim 1, characterized in that, In step (1), the degumming process includes: immersing the carbon fiber in acetone, and drying it after immersion. Preferably, the carbon fiber is immersed in acetone at a temperature of 20-30°C for 1-4 hours. Preferably, the drying temperature is 20-100℃, and the drying time is 1-8 hours; And / or, the acidification treatment step includes: immersing the degummed carbon fiber in concentrated nitric acid, and after immersion, rinsing with water until neutral, and drying; preferably, the immersion temperature of the carbon fiber in concentrated nitric acid is 20-30℃, and the immersion time is 3-7 hours; preferably, the drying temperature is 20-100℃, and the drying time is 1-8 hours; preferably, the mass concentration of the concentrated nitric acid is 60%-68%; And / or, the vacuum degree of the vacuum plasma treatment is 10-60 Pa, the power of the vacuum plasma treatment is 50-300 W, and the duration of the vacuum plasma treatment is 5-30 min.

3. The preparation method of the underwater superbihydrophobic water separation material according to claim 1, characterized in that, In step (2), the process of coating and growing Co(OH)2 nanocrystals on the surface of the pretreated carbon fiber includes the following steps: reacting carbon fiber with cobalt salt reaction solution, washing the reaction product with water and ethanol in sequence after the reaction is completed, and drying.

4. The preparation method of the underwater superbihydrophobic water separation material according to claim 3, characterized in that, The cobalt salt reaction solution includes cobalt salt, alkali source, morphology modifier and water; Preferably, the cobalt salt includes one or more of cobalt nitrate, cobalt chloride, cobalt sulfate, and cobalt acetate; Preferably, the alkali source includes one or more of urea, ammonia, and hexamethylenetetramine; Preferably, the morphology modifier includes ammonium fluoride and / or ammonium hydrogen fluoride; Preferably, the molar ratio of cobalt salt, alkali source, morphology modifier and water in the cobalt salt reaction solution is 1:(2-10):(2.5-10):(278-1111).

5. The preparation method of the underwater superbihydrophobic water separation material according to claim 3, characterized in that, The reaction temperature between the carbon fiber and the cobalt salt reaction solution is 90-150℃, and the reaction time is 6-12h.

6. The method for preparing the underwater superbihydrophobic water separation material according to claim 1, characterized in that, In step (2), the calcination temperature is 300-400℃ and the calcination time is 1-6h; And / or, the heating rate during the calcination process is 2-10℃ / min; And / or, the calcination atmosphere is air or oxygen.

7. The method for preparing the underwater superbihydrophobic water separation material according to claim 1, characterized in that, In step (3), the vulcanizing agent includes one or more of sodium sulfide, sodium hydrosulfide, ammonium sulfide, thiourea, and thioacetamide; And / or, in step (3), the step of converting Co3O4 on the surface of carbon fiber into CoS2 includes: contacting the carbon fiber obtained in step (2) with the vulcanizing agent solution to carry out a vulcanization reaction.

8. The method for preparing the underwater superbihydrophobic water separation material according to claim 7, characterized in that, The concentration of the vulcanizing agent solution is 0.05-0.5 mol / L; And / or, the mass ratio of the carbon fiber to the vulcanizing agent is 1:0.8-5.6; And / or, the temperature of the vulcanization reaction is 120-200°C, and the time of the vulcanization reaction is 10-24h.

9. A submersible superaphthotropic water-separating material, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The application of the underwater super-bihydrophobic water separator material obtained by the preparation method according to any one of claims 1-8 or the underwater super-bihydrophobic water separator material according to claim 9 in the treatment of oily wastewater and the treatment of oil spills.

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