阅读说明：本技术 一种酚醛基超亲水碳纳米纤维网膜的制备方法 (Preparation method of phenolic-based super-hydrophilic carbon nanofiber net film ) 是由 葛建龙 陈鸿 肖颍 黄卓 单浩如 刘其霞 季涛 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种酚醛基超亲水碳纳米纤维网膜及其制备方法,首先将热塑性酚醛树脂和热固性酚醛树脂的混合物、伴纺聚合物以及亲水性纳米颗粒或亲水性纳米颗粒的前驱体加入溶剂中搅拌溶解得到纺丝液,再进行静电纺丝,得到复合前驱体纳米纤维网膜,对复合前驱体纳米纤维网膜进行热处理,再在高纯氮气保护下进行多温段碳化处理,制备得到初生碳纳米纤维网膜,最后对初生碳纳米纤维网膜进行表面亲水性增强处理,获得超亲水碳纳米纤维网膜。本发明的方法以热塑性和热固性酚醛树脂的混合物为主碳源并引入亲水性纳米颗粒,经过表面亲水性增强处理后,获得具有超亲水特性的碳纳米纤维网膜,可用于水包油型油水混合物的高效分离净化。(The invention discloses a phenolic-based super-hydrophilic carbon nanofiber net membrane and a preparation method thereof. The method takes the mixture of thermoplastic and thermosetting phenolic resin as a main carbon source, introduces hydrophilic nano particles, and obtains the carbon nano fiber net film with super-hydrophilic property after surface hydrophilicity enhancement treatment, and the carbon nano fiber net film can be used for high-efficiency separation and purification of oil-in-water type oil-water mixture.)

1. The preparation method of the phenolic-based super-hydrophilic carbon nanofiber net film is characterized by comprising the following steps of:

step (1): adding a mixture of thermoplastic phenolic resin and thermosetting phenolic resin, a companion spinning polymer and hydrophilic nanoparticles or precursors of the hydrophilic nanoparticles into a solvent, stirring and dissolving to obtain a spinning solution;

step (2): performing electrostatic spinning on the spinning solution prepared in the step (1) to prepare a composite precursor nanofiber mesh membrane;

and (3): carrying out heat treatment on the composite precursor nanofiber mesh membrane prepared in the step (2);

and (4): performing multi-temperature-section carbonization treatment on the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) under the protection of high-purity nitrogen to prepare a nascent carbon nanofiber mesh membrane;

and (5): and (4) performing surface hydrophilicity enhancement treatment on the nascent carbon nanofiber mesh membrane obtained in the step (4) to obtain the super-hydrophilic carbon nanofiber mesh membrane.

2. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber mesh film according to claim 1, wherein the mass ratio of the thermoplastic phenolic resin to the thermosetting phenolic resin in the mixture of the thermoplastic phenolic resin and the thermosetting phenolic resin in the step (1) is 1: 9-5: 5.

3. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber mesh membrane as claimed in claim 1, wherein the mass fraction of the mixture of the thermoplastic phenolic resin and the thermosetting phenolic resin in the spinning solution in the step (1) is 5wt% to 10 wt%.

4. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber mesh film according to claim 1, wherein the companion textile polymer in the step (1) is one or a combination of polyvinyl butyral, polyacrylonitrile, polyvinyl alcohol, cellulose acetate, polyvinylidene fluoride, polyurethane or melamine resin.

5. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber mesh membrane as claimed in claim 1, wherein the mass fraction of the co-spun polymer in the spinning solution in the step (1) is 5wt% -15 wt%.

6. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber net film according to claim 1, wherein the hydrophilic nanoparticles in the step (1) are one or more of silicon dioxide nanoparticles, titanium dioxide nanoparticles, tin dioxide nanoparticles, aluminum oxide nanoparticles, zinc oxide nanoparticles, ferroferric oxide nanoparticles, copper oxide nanoparticles, zirconium oxide nanoparticles and molybdenum trioxide nanoparticles; the precursor of the hydrophilic nano-particles is one or a combination of more of ethyl orthosilicate, butyl titanate, stannous chloride, aluminum isopropoxide, zinc chloride, ferric acetylacetonate, copper acetate, zirconium chloride or ammonium molybdate.

7. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber mesh membrane as claimed in claim 1, wherein the mass fraction of the hydrophilic nanoparticles or the precursor of the hydrophilic nanoparticles in the spinning solution in the step (1) is 1wt% to 10 wt%.

8. The method for preparing the phenolic-based superhydrophilic carbon nanofiber mesh membrane according to claim 1, wherein the solvent in the step (1) is one or a combination of N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, water or chloroform.

9. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber mesh film according to claim 1, wherein the electrospinning in the step (2) is performed by using a multi-nozzle electrospinning machine equipped with a uniform-speed reciprocating spraying device and a fiber receiving base material, wherein the fiber receiving base material is one or more of aluminum foil, metal mesh, non-woven fabric and cellulose paper.

10. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber mesh film according to claim 1, wherein the electrostatic spinning parameters in the step (2) are as follows: the spinning voltage is 15-25 kV, the receiving distance is 15-20 cm, the ambient temperature is 20-30 ℃, and the ambient humidity is 20-55%.

11. The method for preparing the phenolic aldehyde based super-hydrophilic carbon nanofiber mesh membrane as claimed in claim 1, wherein the heat treatment in the step (3) is to completely transfer and fix the composite precursor nanofiber mesh membrane between clamping plates with mesh holes, heat the oven to 180-240 ℃, directly put the clamping plates fixed with the composite precursor nanofiber mesh membrane into the oven after the temperature is stabilized, directly take out the clamping plates after the heat treatment for 60-120 min, and naturally cool the clamping plates to room temperature.

12. The method for preparing the phenolic-based super-hydrophilic carbon nanofiber mesh membrane as claimed in claim 1, wherein the carbonization process of the carbonization treatment in the step (4) comprises: under the condition of room temperature, firstly, heating the composite precursor nanofiber mesh membrane subjected to heat treatment to 300-500 ℃ at the heating rate of 2-10 ℃/min in a tubular furnace continuously filled with high-purity nitrogen protective gas, and keeping the temperature for 60-120 min; then, heating to 800-1200 ℃ at a heating rate of 5-10 ℃/min and keeping for 60-120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

13. The method for preparing the phenolic-based superhydrophilic carbon nanofiber web film according to claim 1, wherein the surface hydrophilicity-enhancing treatment in the step (5) includes: one or more of a liquid phase surface oxidation treatment, a plasma surface treatment, or a surface coating treatment.

14. The method for preparing the phenolic aldehyde based super-hydrophilic carbon nanofiber mesh membrane according to claim 13, wherein the liquid phase surface oxidation treatment comprises the steps of immersing the nascent carbon nanofiber mesh membrane in a nitric acid solution with a mass fraction of 65wt% for 12-24 hours, then washing the nascent carbon nanofiber mesh membrane with deionized water until the nascent carbon nanofiber mesh membrane is neutral, and then drying the nascent carbon nanofiber mesh membrane in a vacuum oven.

15. The method for preparing the phenolic aldehyde based super-hydrophilic carbon nanofiber mesh membrane as claimed in claim 13, wherein the plasma surface treatment is to spread and fix the nascent carbon nanofiber mesh membrane on a reactor plate of a plasma modification experimental device, air is used as reaction gas, the treatment power is 1-3 kW, and the treatment time is 5-10 min.

16. The method for preparing the phenolic aldehyde based super-hydrophilic carbon nanofiber mesh membrane according to claim 13, wherein the surface coating treatment comprises the steps of immersing a nascent carbon nanofiber mesh membrane in a dopamine hydrochloride tris buffer solution at room temperature, oscillating for 12-24 hours, washing with deionized water to be neutral, sequentially immersing the obtained carbon nanofiber mesh membrane in a calcium chloride solution and a calcium carbonate solution with the mass fraction of 10wt% for 1min each, circularly immersing for 3-10 times, and finally fully washing and drying the obtained carbon nanofiber mesh membrane with deionized water.

Technical Field

The invention belongs to the technical field of preparation of separation membrane materials, and particularly relates to a preparation method of a phenolic-based super-hydrophilic carbon nanofiber net membrane.

Background

In recent years, due to frequent accidents caused by crude oil leakage and increased discharge of oily sewage generated in industrial and agricultural activities, the pollution of water body oil on the global scale poses a great threat to ecological environment and human health, and therefore, the purification treatment of the oily sewage is urgent. The effective separation of highly mixed or emulsified oil-water mixture is a key step for realizing the purification of oily sewage, and among various oil-water separation technologies, a membrane separation method has the characteristics of good interception performance, wide application range and the like due to the fact that the membrane separation method has pure physical effect and no secondary pollution, and becomes an important development direction of the oily sewage purification treatment technology.

The carbon nanofiber material has excellent physical and chemical stability, high specific surface area, good film forming property and easily-controlled pore structure, and shows good application prospect in the aspect of oil-water separation membrane application. The application research progress of Carbon nanofiber Membrane materials prepared by the electrospinning method in the Oil-Water Separation field is reported in the documents of "Flexible macroporous Carbon nanofiber Membrane with high Oil absorption capacity.J. Mater.chem.A,2014,2, 3557-3562" and "high effective and Flexible electrospan Carbon-silicon nanofiber Membrane for ultra fast gradient-drive Oil-Water Separation, ACS application.Mater.Interface 2014,6, 9393-9401", respectively. The carbon nanofiber membranes prepared by the method are reported to be hydrophobic, the pore structures of the obtained membrane materials are large, and the membrane materials show good application performance in terms of oil slick adsorption on water surface or water-in-oil type oil-water mixture separation, but due to the hydrophobic characteristics of the membrane materials, water cannot infiltrate or pass through the membrane materials, and effective separation of the oil-in-water type oil-water mixture is difficult to achieve.

Domestic patent CN111715081A discloses a preparation method of a hydrophilic nitrogen-doped carbon nanofiber dense network. The method comprises the steps of firstly preparing carbon nanofibers by adopting a vapor phase growth method, then carrying out nitrogen doping treatment to improve the hydrophilicity of the carbon nanofibers, and finally preparing the carbon nanofiber membrane by adopting a vacuum filtration deposition method. However, the process of preparing the carbon nanofiber membrane by the technology is complicated, and the yield and the size of the obtained carbon nanofiber membrane are easily limited to the vapor growth efficiency and the suction filtration device. In addition, the entanglement degree among fibers in the carbon nanofiber membrane prepared by suction filtration deposition is low, and the structural stability of the membrane material is difficult to effectively guarantee.

Disclosure of Invention

The invention aims to solve the problems of the prior art:

(1) most of the existing carbon nanofiber materials are hydrophobic materials, and are not suitable for separating oil-in-water type oil-water mixtures;

(2) the existing hydrophilic carbon nanofiber material preparation technology is complex and high in cost, and the prepared material film is low in structural stability.

The invention provides a preparation method of a phenolic-based super-hydrophilic carbon nanofiber net film, which comprises the following steps:

(1) preparing a carbon nanofiber net film by using phenolic resin as a carbon source and hydrophilic nano fillers as additives through a one-step spinning method;

(2) the obtained carbon nanofiber net film has a cross-linked mesh structure and super-hydrophilic characteristics.

The technical scheme adopted by the invention is as follows:

a phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following steps:

step (1): adding a mixture of thermoplastic phenolic resin and thermosetting phenolic resin, a companion spinning polymer and hydrophilic nanoparticles or precursors of the hydrophilic nanoparticles into a solvent, stirring and dissolving to obtain a spinning solution;

step (2): performing electrostatic spinning on the spinning solution prepared in the step (1) to prepare a composite precursor nanofiber mesh membrane;

and (3): carrying out heat treatment on the composite precursor nanofiber mesh membrane prepared in the step (2);

and (4): performing multi-temperature-section carbonization treatment on the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) under the protection of high-purity nitrogen to prepare a nascent carbon nanofiber mesh membrane;

and (5): and (4) performing surface hydrophilicity enhancement treatment on the nascent carbon nanofiber mesh membrane obtained in the step (4) to obtain the super-hydrophilic carbon nanofiber mesh membrane.

Preferably, the ratio of the thermoplastic phenolic resin to the thermosetting phenolic resin in the mixture of the thermoplastic phenolic resin and the thermosetting phenolic resin in the step (1) is 1: 9-5: 5.

Preferably, the mass fraction of the mixture of the thermoplastic phenolic resin and the thermosetting phenolic resin in the spinning solution in the step (1) is 5wt% to 10 wt%.

Preferably, the companion spinning polymer in step (1) is one or more of polyvinyl butyral, polyacrylonitrile, polyvinyl alcohol, cellulose acetate, polyvinylidene fluoride, polyurethane or melamine resin.

Preferably, the mass fraction of the chaperone-spun polymer in the electrospinning solution of the step (1) is 5wt% to 15 wt%.

Preferably, the hydrophilic nanoparticles in step (1) are one or more of silicon dioxide nanoparticles, titanium dioxide nanoparticles, tin dioxide nanoparticles, aluminum oxide nanoparticles, zinc oxide nanoparticles, ferroferric oxide nanoparticles, copper oxide nanoparticles, zirconium oxide nanoparticles, or molybdenum trioxide nanoparticles.

Preferably, the hydrophilic nanoparticle precursor in step (1) is one or more of ethyl orthosilicate, butyl titanate, stannous chloride, aluminum isopropoxide, zinc chloride, ferric acetylacetonate, copper acetate, zirconium chloride and ammonium molybdate.

Preferably, the mass fraction of the hydrophilic nanoparticles or the precursor of the hydrophilic nanoparticles in the electrospinning solution described in step (1) is 1wt% to 10 wt%.

Preferably, the solvent in step (1) is one or a combination of several of N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, water or chloroform.

Preferably, the electrostatic spinning in the step (2) is carried out by a multi-nozzle electrostatic spinning machine equipped with a uniform speed reciprocating spraying device and a fiber receiving base material, wherein the fiber receiving base material is one or a combination of more of aluminum foil, metal mesh, non-woven fabric and cellulose paper.

Preferably, the electrostatic spinning parameters in the step (2) are as follows: the spinning voltage is 15-25 kV, the receiving distance is 15-20 cm, the ambient temperature is 20-30 ℃, and the ambient humidity is 20-55%.

Preferably, in the step (3), the thermal treatment is to completely transfer and fix the composite precursor nanofiber net film between the clamping plates with the meshes, heat the temperature of the oven to 180-240 ℃, directly put the clamping plates fixed with the composite precursor nanofiber net film into the oven after the temperature is stable, directly take out the clamping plates after the thermal treatment for 60-120 min, and naturally cool the clamping plates to room temperature.

Preferably, the carbonization process of the carbonization treatment in the step (4) includes: under the condition of room temperature, firstly, heating the composite precursor nanofiber mesh membrane subjected to heat treatment to 300-500 ℃ at the heating rate of 2-10 ℃/min in a tubular furnace continuously filled with high-purity nitrogen protective gas, and keeping the temperature for 60-120 min; then, heating to 800-1200 ℃ at a heating rate of 5-10 ℃/min and keeping for 60-120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

Preferably, the method of the surface hydrophilicity-enhancing treatment in the step (5) includes: one or more of a liquid phase surface oxidation treatment, a plasma surface treatment, or a surface coating treatment.

Preferably, the liquid-phase surface oxidation treatment is to immerse the nascent carbon nanofiber mesh membrane in a nitric acid solution with the mass fraction of 65wt% for 12-24 hours, then wash the nascent carbon nanofiber mesh membrane with deionized water to be neutral, and then dry the nascent carbon nanofiber mesh membrane in a vacuum oven.

Preferably, the plasma surface treatment is to tile and fix the nascent carbon nanofiber net film on a reactor polar plate of a plasma modification experimental device, air is used as reaction gas, the treatment power is 1-3 kW, and the treatment time is 5-10 min.

Preferably, the surface coating treatment is to dip the nascent carbon nanofiber mesh membrane in a tris (hydroxymethyl) aminomethane buffer solution of dopamine hydrochloride (PDA) (the dopamine hydrochloride content can be 3.0g/L, and the pH is 8.5), shake for 12-24 h, wash the nascent carbon nanofiber mesh membrane with deionized water to neutrality, sequentially dip the nascent carbon nanofiber mesh membrane in a calcium chloride solution and a calcium carbonate solution with the concentration of 10wt% for 1min each, dip the nascent carbon nanofiber mesh membrane for 3-10 times in a circulating manner, and finally wash the nascent carbon nanofiber mesh membrane with deionized water fully and dry the nascent carbon nanofiber mesh membrane.

According to the invention, the thermoplastic phenolic resin and the thermosetting phenolic resin are mixed, and the thermoplastic characteristic of the thermoplastic phenolic resin is utilized, so that the fibers are bonded to form a stable bonding point, and the structural stability of the obtained carbon nanofiber net film is ensured; and simultaneously, the prepared carbon nanofiber membrane has super-hydrophilic property by introducing hydrophilic particles to mould a multistage rough structure and improving the synergistic effect of the surface energy of the membrane material through the surface hydrophilization treatment of the carbon nanofiber.

According to the method, the mixture of the thermoplastic phenolic resin and the thermosetting phenolic resin and the companion spinning polymer are subjected to blending electrostatic spinning, the thermoplastic phenolic resin is heated and melted to form bonding points among fibers, and meanwhile, the phenolic resin is used as a carbon source, so that the specific surface area and the mechanical property of the obtained carbon nanofiber can be further improved. The hydrophilic particles introduced by the invention have the function of forming a multi-stage rough structure on the surface of the fiber and improving the flexibility of the carbon nanofiber.

Compared with the prior art, the invention has the following beneficial effects:

(1) the method has simple process, takes the mixture of thermoplastic and thermosetting phenolic resin as a main carbon source, introduces hydrophilic nano particles, and obtains the carbon nano fiber net film with super-hydrophilic characteristic and high specific surface area after surface hydrophilicity enhancement treatment, and the carbon nano fiber net film can be used for high-efficiency separation and purification of oil-in-water type oil-water mixtures.

(2) The carbon nanofiber mesh membrane prepared by the method has good bonding points formed among fibers, and the whole carbon nanofiber mesh membrane has stable structure and physical and chemical properties.

(3) The method has the advantages of wide raw material source range, good process adjustability and various sample sizes, and can flexibly adjust and control the pore structure and the surface wettability of the carbon nanofiber net according to the requirements of different oil-containing sewage purification application scenes.

Drawings

Fig. 1(a) is a flexibility test digital photograph of a Polyacrylonitrile (PAN) based carbon nanofiber membrane without functional additives, (b) is a flexibility display digital photograph of a superhydrophilic carbon nanofiber web in example 1 of the present invention;

FIG. 2(a) is a SEM of PAN-based carbon nanofiber membrane without functional additives, (b) is a SEM of a superhydrophilic carbon nanofiber web of example 1 of the present invention;

fig. 3(a) is a static water contact angle test result of a PAN-based carbon nanofiber membrane without functional additives, (b) is a dynamic water contact angle test photograph of a superhydrophilic carbon nanofiber web in example 1 of the present invention;

FIG. 4(a) is an optical micrograph of an oil-in-water emulsion, and (b) is an optical micrograph of a filtrate obtained by separating a carbon nanofiber membrane obtained in example 1.

The specific implementation mode is as follows:

the invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): according to the mass ratio of 1:9, a mixture of thermoplastic phenolic resin and thermosetting phenolic resin is taken as a raw material, polyacrylonitrile is taken as a co-spinning polymer, stannous chloride is taken as an additive, N-dimethylformamide is taken as a solvent, the mass fraction of the phenolic resin mixture is 7 wt%, the mass fraction of polyacrylonitrile is 10wt%, the mass fraction of stannous chloride is 1wt%, and the spinning solution is prepared by fully stirring at room temperature.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is an aluminum foil, the spinning voltage is 25kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 180 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 60min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 2 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 60 min; then, heating to 800 ℃ at the heating rate of 5 ℃/min and keeping for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): and (3) performing surface hydrophilicity enhancement treatment on the nascent carbon nanofiber mesh membrane obtained in the step (4) by adopting a liquid phase surface oxidation method, wherein the specific embodiment is that the nascent carbon nanofiber mesh membrane fixed on a polytetrafluoroethylene mesh plate is firstly soaked in a nitric acid solution with the mass fraction of 65wt% for 24 hours, then the nascent carbon nanofiber mesh membrane is washed to be neutral by deionized water, the nascent carbon nanofiber mesh plate with the carbon nanofiber mesh plate is placed into a vacuum oven to be fully dried, and then the carbon nanofiber mesh membrane is peeled from the surface of the polytetrafluoroethylene mesh plate to obtain the super-hydrophilic carbon nanofiber mesh membrane.

As shown in fig. 1, (a) is a flexibility test digital photo of a PAN-based carbon nanofiber membrane without functional additives, which shows that the membrane material is brittle after being folded and bent, (b) is a flexibility display digital photo of the superhydrophilic carbon nanofiber web in this embodiment, which shows that the membrane material has good bending resistance and can still maintain a complete structure after being folded, so that it can be seen that the carbon nanofiber membrane obtained in this embodiment has good flexibility compared with a conventional PAN-based carbon nanofiber membrane; as shown in fig. 2, (a) is a scanning electron microscope photograph of the PAN-based carbon nanofiber membrane without functional additives, and a large number of bonding points are not formed between fibers, (b) is a scanning electron microscope photograph of the superhydrophilic carbon nanofiber web in this example, it can be seen that a large number of bonding structures are formed between fibers, and it can be seen that compared with the conventional PAN-based carbon nanofiber membrane, a large number of cross-linked network structures are formed between fibers in the carbon nanofiber membrane obtained in this example; as shown in fig. 3, (a) is a static water contact angle test result of the PAN-based carbon nanofiber membrane without the functional additive, the static water contact angle of the surface of the fiber membrane reaches 135 °, and the fiber membrane is hydrophobic, (b) is a dynamic water contact angle test photograph of the superhydrophilic carbon nanofiber web film in this embodiment, 2 μ l of water drop can completely infiltrate the fiber membrane after 319ms, and the water contact angle test result shows that the carbon nanofiber web film obtained in this embodiment has superhydrophilic properties compared with the hydrophobic properties of the conventional PAN-based carbon nanofiber membrane. The carbon nanofiber membrane obtained in the embodiment has separation flux of 2428 L.m for an n-hexane/water emulsified oil-water mixture under the drive of the self weight of liquid^-2·h^-1The separation efficiency was 95.8%, and fig. 4 is an optical micrograph of the oil-water emulsion before separation and the filtrate after separation, in which (a) is an optical micrograph of the oil-in-water emulsion, it can be seen that a large amount of oil droplets are present in the emulsion, and (b) is an optical micrograph of the oil-in-water emulsion of this exampleIn the example, the optical microscope photograph of the filtrate after the separation of the carbon nanofiber membrane shows that oil droplets in water are separated.

Example 2

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): according to the mass ratio of 1:9, a mixture of thermoplastic phenolic resin and thermosetting phenolic resin is taken as a raw material, polyvinyl butyral is taken as a co-spinning polymer, stannous chloride is taken as an additive, N-dimethylformamide is taken as a solvent, the mass fraction of the phenolic resin mixture is 5wt%, the mass fraction of the polyvinyl butyral is 5wt%, the mass fraction of the stannous chloride is 7 wt%, and the spinning solution is prepared by fully stirring at room temperature.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is an aluminum foil, the spinning voltage is 25kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 240 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 60min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 2 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 60 min; then, heating to 850 ℃ at the heating rate of 5 ℃/min and keeping the temperature for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): and (3) performing surface hydrophilicity enhancement treatment on the nascent carbon nanofiber mesh membrane obtained in the step (4) by adopting a liquid phase surface oxidation method, wherein the specific embodiment is that the nascent carbon nanofiber mesh membrane fixed on a polytetrafluoroethylene mesh plate is firstly immersed in a nitric acid solution with the mass fraction of 65wt% for 12 hours, then the nascent carbon nanofiber mesh membrane is washed to be neutral by deionized water, the polytetrafluoroethylene mesh plate is connected with the carbon nanofiber mesh plate and placed into a vacuum oven for full drying, and then the carbon nanofiber mesh membrane is peeled from the surface of the polytetrafluoroethylene mesh plate to obtain the super-hydrophilic carbon nanofiber mesh membrane.

Example 3

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): according to the mass ratio of 2:8, water-soluble phenolic resin (mixture of thermoplastic and thermosetting) is taken as a raw material, polyvinyl alcohol is taken as a companioning polymer, silicon dioxide nanoparticles are taken as an additive, water is taken as a solvent, the mass fraction of the phenolic resin mixture is 10wt%, the mass fraction of the polyvinyl alcohol is 8 wt%, the mass fraction of the silicon dioxide nanoparticles is 6 wt%, the mixture is heated in a water bath at 60 ℃, and is fully stirred and then is subjected to ultrasonic dispersion treatment for 15min to obtain the spinning solution.

Step (2): and (2) adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is a metal net, the spinning voltage is 25kV, the receiving distance is 15cm, the ambient temperature is 30 +/-3 ℃, the ambient humidity is 20 +/-5%, and the composite precursor nanofiber mesh film with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 240 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 10 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 80 min; then, heating to 1200 ℃ at a heating rate of 10 ℃/min and keeping for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the steps of adopting plasma to carry out surface treatment on a nascent carbon nanofiber net membrane, specifically, flatly paving and fixing the nascent carbon nanofiber net membrane on a reactor polar plate of a plasma modification experiment device, taking air as reaction gas, setting the treatment power to be 3kW, and stripping the nascent carbon nanofiber net membrane from the polar plate after 5min of treatment to obtain the super-hydrophilic carbon nanofiber net membrane.

Example 4

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): taking phenolic resin (a mixture of thermoplastic and thermosetting resins) as a raw material according to a mass ratio of 1:9, taking cellulose acetate as a co-spinning polymer, taking tin dioxide nanoparticles as an additive, taking chloroform as a solvent, taking the mass fraction of the phenolic resin mixture as 10wt%, the mass fraction of the cellulose acetate as 10wt% and the mass fraction of the tin dioxide nanoparticles as 6 wt%, heating in a water bath at 60 ℃, fully stirring, and performing ultrasonic dispersion treatment for 15min to obtain a spinning solution.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is non-woven fabric, the spinning voltage is 20kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 240 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 5 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 120 min; then, heating to 850 ℃ at the heating rate of 5 ℃/min and keeping the temperature for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the steps of adopting plasma to carry out surface treatment on a nascent carbon nanofiber net membrane, specifically, flatly paving and fixing the nascent carbon nanofiber net membrane on a reactor polar plate of a plasma modification experiment device, taking air as reaction gas, setting the treatment power to be 1kW, and stripping the nascent carbon nanofiber net membrane from the polar plate after 10min of treatment to obtain the super-hydrophilic carbon nanofiber net membrane.

Example 5

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): according to the mass ratio of 5:5, taking phenolic resin (a mixture of thermoplasticity and thermosetting) as a raw material, taking polyvinylidene fluoride as a companioning polymer, taking a mixture of aluminum trioxide nanoparticles and ferroferric oxide nanoparticles as an additive, taking N, N-dimethylformamide as a solvent, fully stirring the mixture of the phenolic resin and the ferroferric oxide nanoparticles, and performing ultrasonic dispersion treatment for 15min to obtain a spinning solution, wherein the mass fraction of the phenolic resin mixture is 10wt%, the mass fraction of the polyvinylidene fluoride is 10wt%, the mass fraction of the aluminum trioxide nanoparticles is 3 wt%, and the mass fraction of the ferroferric oxide nanoparticles is 3 wt%.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is non-woven fabric, the spinning voltage is 25kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 240 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 5 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 120 min; then, heating to 850 ℃ at the heating rate of 5 ℃/min and keeping the temperature for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the specific steps of immersing the nascent carbon nanofiber mesh membrane in a tris (hydroxymethyl) aminomethane buffer solution of dopamine hydrochloride (PDA) (the dopamine hydrochloride content is 3.0g/L, and the pH value is 8.5) at room temperature, oscillating for 12 hours, washing with deionized water to be neutral, sequentially immersing the obtained carbon nanofiber mesh membrane in a calcium chloride solution and a calcium carbonate solution with the mass fraction of 10wt% for 1min respectively, circularly immersing for 3 times, and fully washing and drying the obtained carbon nanofiber mesh membrane with the deionized water to obtain the super-hydrophilic carbon nanofiber mesh membrane.

Example 6

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): taking phenolic resin (a mixture of thermoplasticity and thermosetting) as a raw material, taking soluble polyurethane as a companding polymer, taking a mixture of zinc oxide nanoparticles and copper oxide nanoparticles as an additive, taking N-methyl pyrrolidone as a solvent, taking the mass fraction of the phenolic resin mixture as 10wt%, the mass fraction of polyurethane as 10wt%, the mass fraction of zinc oxide nanoparticles as 2 wt% and the mass fraction of copper oxide nanoparticles as 3 wt%, fully stirring, and performing ultrasonic dispersion treatment for 15min to obtain a spinning solution.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is non-woven fabric, the spinning voltage is 25kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 180 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane to 300 ℃ from room temperature at a heating rate of 2 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 120 min; then, heating to 800 ℃ at the heating rate of 5 ℃/min and keeping for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the steps of adopting plasma to carry out surface treatment on a nascent carbon nanofiber net membrane, specifically, flatly paving and fixing the nascent carbon nanofiber net membrane on a reactor polar plate of a plasma modification experiment device, taking air as reaction gas, setting the treatment power to be 2kW, and stripping the nascent carbon nanofiber net membrane from the polar plate after 8min of treatment to obtain the super-hydrophilic carbon nanofiber net membrane.

Example 7

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): according to the mass ratio of 1:9, a mixture of thermoplastic phenolic resin and thermosetting phenolic resin is taken as a raw material, polyacrylonitrile is taken as a companioning polymer, titanium dioxide nanoparticles are taken as an additive, N-dimethylformamide is taken as a solvent, the mass fraction of the phenolic resin mixture is 10wt%, the mass fraction of polyacrylonitrile is 15wt%, the mass fraction of titanium dioxide nanoparticles is 10wt%, and the spinning solution is obtained by fully stirring and then carrying out ultrasonic dispersion treatment for 15 min.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is an aluminum foil, the spinning voltage is 25kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 200 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 2 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 60 min; then, heating to 850 ℃ at the heating rate of 5 ℃/min and keeping the temperature for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the specific steps of immersing the nascent carbon nanofiber mesh membrane in a tris (hydroxymethyl) aminomethane buffer solution of dopamine hydrochloride (PDA) (the dopamine hydrochloride content is 3.0g/L, and the pH value is 8.5) at room temperature, oscillating for 24 hours, washing with deionized water to be neutral, sequentially immersing the obtained carbon nanofiber mesh membrane in a calcium chloride solution and a calcium carbonate solution with the mass fraction of 10wt% for 1min respectively, circularly immersing for 3 times, and fully washing and drying the obtained carbon nanofiber mesh membrane with the deionized water to obtain the super-hydrophilic carbon nanofiber mesh membrane.

Example 8

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): according to the mass ratio of 1:9, a mixture of thermoplastic phenolic resin and thermosetting phenolic resin is taken as a raw material, melamine resin and polyvinylidene fluoride are taken as a companioning polymer, zirconia nanoparticles, molybdenum trioxide nanoparticles and ferroferric oxide nanoparticles are taken as additives, N-dimethylformamide is taken as a solvent, the mass fraction of the phenolic resin mixture is 5wt%, the mass fraction of the melamine resin is 5wt%, the mass fraction of the polyvinylidene fluoride is 5wt%, the mass fraction of the zirconia nanoparticles is 2 wt%, the mass fraction of the molybdenum trioxide nanoparticles is 2 wt%, the mass fraction of the ferroferric oxide nanoparticles is 2 wt%, and the spinning solution is obtained by fully stirring and then carrying out ultrasonic dispersion treatment for 15 min.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is non-woven fabric, the spinning voltage is 25kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 200 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 2 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 60 min; then, heating to 850 ℃ at the heating rate of 5 ℃/min and keeping the temperature for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the steps of adopting plasma to carry out surface treatment on a nascent carbon nanofiber net membrane, specifically, flatly paving and fixing the nascent carbon nanofiber net membrane on a reactor polar plate of a plasma modification experiment device, taking air as reaction gas, setting the treatment power to be 3kW, and stripping the nascent carbon nanofiber net membrane from the polar plate after 5min of treatment to obtain the super-hydrophilic carbon nanofiber net membrane.

Example 9

Step (1): according to the mass ratio of 1:9, a mixture of thermoplastic phenolic resin and thermosetting phenolic resin is taken as a raw material, polyvinyl butyral is taken as a co-spinning polymer, butyl titanate and stannous chloride are taken as additives, N-dimethylformamide is taken as a solvent, the mass fraction of the phenolic resin mixture is 5wt%, the mass fraction of the polyvinyl butyral is 5wt%, the mass fraction of the butyl titanate is 5wt%, and the mass fraction of the stannous chloride is 5wt%, and the spinning solution is prepared by fully stirring at room temperature.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is an aluminum foil, the spinning voltage is 15kV, the receiving distance is 15cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 200 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 2 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 60 min; then, heating to 850 ℃ at the heating rate of 5 ℃/min and keeping the temperature for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the steps of adopting plasma to carry out surface treatment on a nascent carbon nanofiber net membrane, specifically, flatly paving and fixing the nascent carbon nanofiber net membrane on a reactor polar plate of a plasma modification experiment device, taking air as reaction gas, setting the treatment power to be 2kW, and stripping the nascent carbon nanofiber net membrane from the polar plate after 10min of treatment to obtain the super-hydrophilic carbon nanofiber net membrane.

Example 10

Step (1): according to the mass ratio of 1:9, a mixture of thermoplastic phenolic resin and thermosetting phenolic resin is taken as a raw material, polyvinyl butyral is taken as a co-spinning polymer, aluminum isopropoxide and stannous chloride are taken as additives, N-dimethylformamide is taken as a solvent, the mass fraction of the phenolic resin mixture is 10wt%, the mass fraction of polyvinyl butyral is 5wt%, the mass fraction of aluminum isopropoxide is 4 wt%, and the mass fraction of stannous chloride is 4 wt%, and the spinning solution is prepared by fully stirring at room temperature.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is an aluminum foil, the spinning voltage is 25kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 180 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 60min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 2 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 60 min; then, heating to 1000 ℃ at a heating rate of 5 ℃/min and keeping for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the specific steps of immersing the nascent carbon nanofiber mesh membrane in a tris (hydroxymethyl) aminomethane buffer solution of dopamine hydrochloride (PDA) (the dopamine hydrochloride content is 3.0g/L, and the pH value is 8.5) at room temperature, oscillating for 12 hours, washing with deionized water to be neutral, sequentially immersing the obtained carbon nanofiber mesh membrane in a calcium chloride solution and a calcium carbonate solution with the mass fractions of 10wt% for 1min respectively, circularly immersing for 10 times, and fully washing and drying the obtained carbon nanofiber mesh membrane with the deionized water to obtain the super-hydrophilic carbon nanofiber mesh membrane.

Example 11

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): according to the mass ratio of 3:7, taking phenolic resin (a mixture of thermoplasticity and thermosetting property) as a raw material, taking polyvinylidene fluoride as a companioning polymer, taking a mixture of zinc chloride and copper acetate as an additive, taking N, N-dimethylformamide as a solvent, wherein the mass fraction of the phenolic resin mixture is 10wt%, the mass fraction of the polyvinylidene fluoride is 10wt%, the mass fraction of the zinc chloride is 3 wt%, and the mass fraction of the copper acetate is 3 wt%, and fully stirring to obtain the spinning solution.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is non-woven fabric, the spinning voltage is 25kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 240 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 5 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 120 min; then, heating to 850 ℃ at the heating rate of 5 ℃/min and keeping the temperature for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the steps of adopting plasma to carry out surface treatment on a nascent carbon nanofiber net membrane, specifically, flatly paving and fixing the nascent carbon nanofiber net membrane on a reactor polar plate of a plasma modification experiment device, taking air as reaction gas, setting the treatment power to be 3kW, and stripping the nascent carbon nanofiber net membrane from the polar plate after 5min of treatment to obtain the super-hydrophilic carbon nanofiber net membrane.

Example 12

Step (1): taking water-based phenolic resin (a mixture of thermoplastic and thermosetting resins) as a raw material, taking cellulose acetate as a co-spinning polymer, taking a mixture of ferric acetylacetonate and zirconium acetylacetonate as an additive, taking chloroform as a solvent, fully stirring the mixture according to the mass ratio of 2:8 to obtain a spinning solution, wherein the mass fraction of the phenolic resin mixture is 10wt%, the mass fraction of the cellulose acetate is 10wt%, the mass fraction of the ferric acetylacetonate is 3 wt%, and the mass fraction of the zirconium acetylacetonate is 3 wt%.

Step (2): and (2) adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is a metal net, the spinning voltage is 20kV, the receiving distance is 20cm, the ambient temperature is 25 +/-3 ℃, the ambient humidity is 50 +/-5%, and the composite precursor nanofiber mesh film with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 240 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 5 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 120 min; then, heating to 850 ℃ at the heating rate of 5 ℃/min and keeping the temperature for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): the method comprises the steps of adopting plasma to carry out surface treatment on a nascent carbon nanofiber net membrane, specifically, flatly paving and fixing the nascent carbon nanofiber net membrane on a reactor polar plate of a plasma modification experiment device, taking air as reaction gas, setting the treatment power to be 1kW, and stripping the nascent carbon nanofiber net membrane from the polar plate after 10min of treatment to obtain the super-hydrophilic carbon nanofiber net membrane.

Example 13

A phenolic aldehyde based super-hydrophilic carbon nanofiber net film and a preparation method thereof comprise the following specific steps:

step (1): taking aqueous phenolic resin (mixture of thermoplastic and thermosetting) as a raw material, polyvinyl alcohol as a companding polymer, ammonium molybdate as an additive, water as a solvent, 8 wt% of the phenolic resin mixture, 8 wt% of the polyvinyl alcohol and 1wt% of the ammonium molybdate, heating in a water bath at 60 ℃, fully stirring, and performing ultrasonic dispersion treatment for 15min to obtain the spinning solution.

Step (2): and adding the spinning solution into a multi-nozzle electrostatic spinning machine provided with a uniform-speed reciprocating spraying device and a fiber receiving base material to carry out electrostatic spinning, wherein the fiber receiving base material is cellulose paper, the spinning voltage is 25kV, the receiving distance is 15cm, the ambient temperature is 30 +/-3 ℃, the ambient humidity is 20 +/-5%, and the composite precursor nanofiber mesh membrane with uniform thickness is prepared.

And (3): and (3) completely transferring the composite precursor nanofiber mesh membrane prepared in the step (2) from the receiving base material and fixing the composite precursor nanofiber mesh membrane between polytetrafluoroethylene clamping plates with meshes, then heating the temperature of the oven to 240 ℃, directly putting the polytetrafluoroethylene mesh plate fixed with the composite precursor nanofiber mesh membrane into the oven for heat treatment for 120min after the temperature is stable, directly taking out the polytetrafluoroethylene mesh plate, and naturally cooling the polytetrafluoroethylene mesh plate to room temperature in the air.

And (4): fixing the composite precursor nanofiber mesh membrane subjected to heat treatment in the step (3) between two graphite plates, heating the composite precursor nanofiber mesh membrane from room temperature to 500 ℃ at a heating rate of 10 ℃/min under the protection of high-purity nitrogen, and keeping the temperature for 120 min; then, heating to 800 ℃ at a heating rate of 10 ℃/min and keeping for 120 min; and finally, naturally cooling to room temperature to prepare the nascent carbon nanofiber mesh membrane.

And (5): and (3) performing surface hydrophilicity enhancement treatment on the nascent carbon nanofiber mesh membrane obtained in the step (4) by adopting a liquid phase surface oxidation method, wherein the specific embodiment is that the nascent carbon nanofiber mesh membrane fixed on a polytetrafluoroethylene mesh plate is firstly soaked in a nitric acid solution with the mass fraction of 65wt% for 24 hours, then the nascent carbon nanofiber mesh membrane is washed to be neutral by deionized water, the nascent carbon nanofiber mesh plate with the carbon nanofiber mesh plate is placed into a vacuum oven to be fully dried, and then the carbon nanofiber mesh membrane is peeled from the surface of the polytetrafluoroethylene mesh plate to obtain the super-hydrophilic carbon nanofiber mesh membrane.

The hydrophilicity test of the super-hydrophilic carbon nanofiber mesh membrane prepared in the embodiment shows that the static water contact angle of the super-hydrophilic carbon nanofiber mesh membrane can reach 0 degrees, and the carbon nanofiber mesh membrane prepared by the preparation method provided by the invention has the super-hydrophilic characteristic and can be used for efficient separation and purification of oil-in-water oil-water mixtures.