Super-hydrophobic polyacrylonitrile fiber membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of super-hydrophobic materials, in particular to a super-hydrophobic polyacrylonitrile fiber membrane and a preparation method and application thereof. The super-hydrophobic polyacrylonitrile fiber membrane is prepared from the following raw materials in parts by mass: 1 to 1.5 parts of polyacrylonitrile, 0.1 to 1.5 parts of an amino silane covalent modifier, 0.1 to 0.8 part of a hydrophobic modifier, 0.1 to 1.5 parts of nanoparticles and 9 to 11 parts of a solvent. According to the invention, through a covalent anchoring effect, an amino silane covalent modifier is used as a molecular bridge to anchor nanoparticles and a hydrophobic modifier on a polyacrylonitrile matrix. And meanwhile, a multi-scale micron / nano composite rough surface structure is constructed by utilizing an electrostatic spinning technology, so that the super-hydrophobic performance is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of super-hydrophobic materials, and in particular to a super-hydrophobic polyacrylonitrile fiber membrane, a preparation method thereof, and applications thereof. Background Art

[0002] Superhydrophobic materials have shown great application potential in many fields. Among them, fluorine-containing superhydrophobic materials have attracted much attention due to their excellent hydrophobic properties. However, with the deepening of research, the shortcomings of fluorine-containing superhydrophobic materials have gradually been exposed. From an environmental perspective, fluorine-containing compounds are difficult to degrade and accumulate in the environment for a long time, which will cause damage to the ecosystem; in terms of human health, some fluorine-containing substances may interfere with the endocrine system after entering the human body, posing a potential threat to human health. Based on these problems, more and more people have begun to oppose the use of fluorine-containing materials. The development of fluoride-free superhydrophobic materials has become an important research direction in the field of materials science. This not only helps to solve environmental and health risks, but also opens up new paths for the sustainable development of superhydrophobic materials.

[0003] Superhydrophobic materials have important applications in oil-water separation, including membrane separation and adsorption technologies. However, traditional separation technologies also face environmental pollution issues during their application. Therefore, the development of efficient and environmentally friendly superhydrophobic materials for oil-water separation is of great practical significance. It can reduce secondary pollution during the separation process and improve resource recovery rate, playing a dual role in promoting environmental protection and resource utilization. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the existing fluorine-containing super-hydrophobic materials and the environmental pollution problem of the existing oil-water separation technology, thereby providing a super-hydrophobic polyacrylonitrile fiber membrane and its preparation method and application.

[0005] To this end, the present invention provides the following technical solutions: A super-hydrophobic polyacrylonitrile fiber membrane comprises the following raw materials in parts by weight: 1-1.5 parts of polyacrylonitrile, 0.1-1.5 parts of aminosilane covalent modifier, 0.1-0.8 parts of hydrophobic modifier, 0.1-1.5 parts of nanoparticles, and 9-11 parts of solvent.

[0006] In some embodiments of the present invention, the mass fraction of the polyacrylonitrile is preferably 1-1.4 parts, the mass fraction of the aminosilane covalent modifier is preferably 0.15-1.35 parts, the mass fraction of the hydrophobic modifier is preferably 0.2-0.6 parts, and the mass fraction of the nanoparticles is preferably 0.2-1.3 parts.

[0007] In some embodiments of the present invention, the aminosilane covalent modifier includes one or more of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, 3-aminopropylmethyldimethoxysilane, bis(3-aminopropyl)dimethoxysilane, 3-aminopropyltriisopropoxysilane, (2-aminoethyl)trimethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldiethoxysilane and 3-aminobutyltrimethoxysilane.

[0008] In some embodiments of the present invention, the hydrophobic modifier includes one or more of methyltrimethoxysilane, methyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, and hexadecyltriethoxysilane.

[0009] In some embodiments of the present invention, the nanoparticles include one or more of silicon dioxide, titanium dioxide, silicon nitride, and silicon carbide.

[0010] In some embodiments of the present invention, the solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, acetonitrile, acetone and tetrahydrofuran.

[0011] The present invention also provides a method for preparing the above-mentioned super-hydrophobic polyacrylonitrile fiber membrane, comprising the following steps: The super-hydrophobic polyacrylonitrile fiber membrane is obtained by mixing polyacrylonitrile, an aminosilane covalent modifier, a hydrophobic modifier, nanoparticles and a solvent and performing electrostatic spinning.

[0012] In some embodiments of the present invention, the mixing time is preferably 6-24 h, more preferably 8-20 h, the mixing stirring rate is preferably 100-350 rpm, more preferably 150-350 rpm, and the mixing temperature is preferably 25-60°C, more preferably 35-50°C.

[0013] In some embodiments of the present invention, the electrospinning voltage is preferably 15-30 kV, more preferably 18-28 kV, and the electrospinning distance is preferably 12-25 cm, more preferably 14-22 cm.

[0014] In some embodiments of the present invention, the rolling speed of the electrospinning receiver is preferably 40-350 rpm, more preferably 50-300 rpm, and the feed rate of the electrospinning is preferably 0.8-2.5 mL / h, more preferably 0.8-2.5 mL / h.

[0015] The present invention also provides the use of the super-hydrophobic polyacrylonitrile fiber membrane or the super-hydrophobic polyacrylonitrile fiber membrane prepared by the method for preparing the super-hydrophobic polyacrylonitrile fiber membrane in oil-water separation.

[0016] The technical solution of the present invention has the following advantages: The present invention provides a super-hydrophobic polyacrylonitrile fiber membrane comprising the following raw materials by weight: 1-1.5 parts polyacrylonitrile, 0.1-1.5 parts aminosilane covalent modifier, 0.1-0.8 parts hydrophobic modifier, 0.1-1.5 parts nanoparticles, and 9-11 parts solvent. The raw materials used in the present invention do not contain fluorine, thus eliminating the environmental and health risks associated with fluorine and aligning with the concept of green chemistry.

[0017] The present invention forms a chemical bond between the hydrophobic functional group and the aminosilane covalent modifier, and at the same time, the covalent modifier and the matrix polyacrylonitrile form a chemical bond. The presence of this chemical bond not only enhances the hydrophobicity of the material, but also greatly improves the stability and cyclic stability of the material. Even after repeated use and complex environmental conditions, the material can still maintain good superhydrophobic properties, providing a reliable guarantee for the practical application of superhydrophobic materials.

[0018] The aminosilane covalent modifier of the present invention serves as a bifunctional molecular bridging agent, and its amino group (-NH2) can form a covalent bond with the cyano group (-C≡N) of polyacrylonitrile to achieve surface functionalization of the polyacrylonitrile; the other end combines with the methoxy group in the hydrophobic modifier and the hydroxyl group on the surface of the nanoparticles through a hydrolysis condensation reaction to form a siloxane network structure (Si-O-Si bond), thereby simultaneously achieving hydrophobic functionalization and particle anchoring.

[0019] The present invention also provides a preparation method of a super-hydrophobic polyacrylonitrile fiber membrane, comprising the steps of: mixing polyacrylonitrile, an aminosilane covalent modifier, a hydrophobic modifier, nanoparticles, and a solvent, and electrostatic spinning to obtain the super-hydrophobic polyacrylonitrile fiber membrane. The present invention uses a covalent anchoring effect to anchor the nanoparticles and the hydrophobic modifier to the polyacrylonitrile substrate using an aminosilane covalent modifier as a "molecular bridge." Utilizing electrostatic spinning technology simultaneously, a multi-scale micro / nano composite rough surface structure is constructed to achieve super-hydrophobic performance.

[0020] The preparation method provided by the present invention, through the synergistic effect of a micro / nano composite rough structure and a chemically bonded interface, breaks through the technical bottleneck of the insufficient environmental durability of traditional superhydrophobic materials. The synergistic effect of the micro / nano composite rough structure and the chemically bonded interface significantly improves the environmental durability of the polyacrylonitrile fiber membrane while also maintaining excellent superhydrophobic properties. It can achieve efficient oil-water separation in the field of oil-water separation, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 1 is a SEM image of the super-hydrophobic polyacrylonitrile fiber membrane prepared in Examples 1-3 of the present invention and the polyacrylonitrile fiber membrane prepared in Comparative Examples 1-3; in, Figure 1 (a) is the SEM image of Example 1; Figure 1 (b) is the SEM image of Example 2; Figure 1 (c) is the SEM image of Example 3; Figure 1 (d) is the SEM image of Comparative Example 1; Figure 1 (e) is the SEM image of Comparative Example 2; Figure 1 (f) is the SEM image of Comparative Example 3; Figure 2 FTIR images of the super-hydrophobic polyacrylonitrile fiber membrane prepared in Example 1 of the present invention and the polyacrylonitrile fiber membranes prepared in Comparative Examples 1-3; Figure 3 Graphs showing water contact angles of the super-hydrophobic polyacrylonitrile fiber membranes prepared in Examples 1-3 of the present invention and the polyacrylonitrile fiber membranes prepared in Comparative Examples 1-3; in, Figure 1 (a) is the water contact angle test diagram of Example 1; Figure 1 (b) is the water contact angle test diagram of Example 2; Figure 1 (c) is the water contact angle test diagram of Example 3; Figure 1 (d) is the water contact angle test diagram of Comparative Example 1; Figure 1 (e) is the water contact angle test diagram of comparative example 2; Figure 1 (f) is the water contact angle test diagram of comparative example 3; Figure 4 1 is a stability test chart of the super-hydrophobic polyacrylonitrile fiber membrane prepared in Example 1 of the present invention; in, Figure 4 (a) is the ultrasonic stability test diagram; Figure 4 (b) is the tape peeling test diagram; Figure 4 (c) is the pH immersion test diagram; Figure 4 (d) is the organic solvent immersion test diagram; Figure 4 (e) is the temperature stability test diagram; Figure 4 (f) is a long-term exposure environment test diagram; Figure 5This is a test chart of the wettability and anti-pollution properties of the super-hydrophobic polyacrylonitrile fiber membrane prepared in Example 1 of the present invention; in, Figure 5 (a) is a static hydrophobicity test diagram; Figure 5 (b) is the oil absorption test chart; Figure 5 (c) is the test diagram of water pollution resistance under oil; Figure 5 (d) is the self-cleaning test diagram; Figure 6 This is a test chart of the oil-water separation performance of the super-hydrophobic polyacrylonitrile fiber membrane prepared in Example 1 of the present invention; in, Figure 6 (a) Schematic diagram of oil-water separation process; Figure 6 (b) is the oil absorption weight gain test chart; Figure 6 (c) Comparison of oil-water mixture separation flux / efficiency of different models; Figure 6 (d) is the cycle stability test diagram; Figure 6 (e) Schematic diagram of the continuous oil absorption-desorption separation device; Figure 7 This is a test chart of the water-in-oil emulsion separation performance of the super-hydrophobic polyacrylonitrile fiber membrane prepared in Example 1 of the present invention; in, Figure 7 (a) Schematic diagram of water-in-oil emulsion separation; Figure 7 (b) Schematic diagram of digital microscope and optical microscope before and after separation; Figure 7 (c) Comparison of separation flux and efficiency of different types of water-in-oil emulsions; Figure 7 (d) Cyclic stability test diagram; Figure 7 (e) Bar graph of water contact angle corresponding to the number of separation cycles; Figure 7 (f) is a graph showing the long-term separation stability and regeneration performance test.

[0023] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0024] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents. DETAILED DESCRIPTION Example

[0025] This embodiment provides a super-hydrophobic polyacrylonitrile fiber membrane, comprising: 1.0 g of polyacrylonitrile, 0.5 g of (3-aminopropyl)triethoxysilane, 0.45 g of dodecyltriethoxysilane, 0.5 g of silicon dioxide, and 10 g of N,N-dimethylformamide.

[0026] The preparation method of super-hydrophobic polyacrylonitrile fiber membrane comprises: 1.0 g of polyacrylonitrile, 0.5 g of (3-aminopropyl)triethoxysilane, 0.45 g of dodecyltriethoxysilane, 0.5 g of silica and 10 g of N,N-dimethylformamide were mixed, stirred at 350 rpm and 40°C for 12 h, and a superhydrophobic polyacrylonitrile fiber membrane was prepared by electrospinning.

[0027] The electrospinning parameters were as follows: electrospinning voltage of 19 kV, spinning distance of 18 cm, receiver rolling speed of 120 rpm, and electrospinning feed rate of 1.0 mL / h.

[0028] The water contact angle of the super-hydrophobic polyacrylonitrile fiber membrane obtained in this example is 161.3°, and the separation flux of the mixture of dichloromethane and water is higher than 3921Lm -2 h -1 , the separation efficiency is above 98.8%; the separation flux of oil-in-water (dichloromethane-water) emulsion is higher than 685Lm -2 h -1 , the separation efficiency is above 98.2%. Example

[0029] This embodiment provides a super-hydrophobic polyacrylonitrile fiber membrane, comprising: 1.1 g of polyacrylonitrile, 0.25 g of (3-aminopropyl)triethoxysilane, 0.4 g of dodecyltriethoxysilane, 0.5 g of silicon dioxide, and 10 g of N,N-dimethylformamide.

[0030] The preparation method of super-hydrophobic polyacrylonitrile fiber membrane comprises: 1.1 g of polyacrylonitrile, 0.25 g of (3-aminopropyl)triethoxysilane, 0.4 g of dodecyltriethoxysilane, 0.5 g of silica and 10 g of N,N-dimethylformamide were mixed, stirred at 350 rpm and 40°C for 12 h, and a superhydrophobic polyacrylonitrile fiber membrane was prepared by electrospinning.

[0031] The electrospinning parameters were as follows: electrospinning voltage of 29 kV, spinning distance of 18 cm, receiver rolling speed of 120 rpm, and electrospinning feed rate of 1.2 mL / h.

[0032] The water contact angle of the super-hydrophobic polyacrylonitrile fiber membrane obtained in this example was 157.1°, and the separation flux of the mixture of 1,2-dichloroethane and water was higher than 3668 Lm -2 h -1 , the separation efficiency is above 98.8%; the separation flux of oil-in-water (1,2-dichloroethane-water) emulsion is higher than 679Lm -2 h -1 , the separation efficiency is above 98.2%. Example

[0033] This embodiment provides a super-hydrophobic polyacrylonitrile fiber membrane, comprising: 1.4 g of polyacrylonitrile, 0.2 g of (3-aminopropyl)triethoxysilane, 0.2 g of dodecyltriethoxysilane, 0.5 g of silicon dioxide, and 10 g of N,N-dimethylformamide.

[0034] The preparation method of super-hydrophobic polyacrylonitrile fiber membrane comprises: 1.4 g of polyacrylonitrile, 0.2 g of (3-aminopropyl)triethoxysilane, 0.2 g of dodecyltriethoxysilane, 0.5 g of silica and 10 g of N,N-dimethylformamide were mixed, stirred at 300 rpm and 40°C for 14 h, and a superhydrophobic polyacrylonitrile fiber membrane was prepared by electrospinning.

[0035] The electrospinning parameters were as follows: electrospinning voltage of 22 kV, spinning distance of 16 cm, receiver rolling speed of 120 rpm, and electrospinning feed rate of 1.3 mL / h.

[0036] The water contact angle of the super-hydrophobic polyacrylonitrile fiber membrane obtained in this example was 154.4°, and the separation flux of the mixture of bromobenzene and water was higher than 4177 Lm -2 h -1 , the separation efficiency is above 98.8%; the separation flux of oil-in-water (bromobenzene-water) emulsion is higher than 709Lm -2 h -1 , the separation efficiency is above 98.2%. Example

[0037] This embodiment provides a super-hydrophobic polyacrylonitrile fiber membrane, comprising: 1.5 g of polyacrylonitrile, 0.6 g of (3-aminopropyl)triethoxysilane, 0.25 g of dodecyltriethoxysilane, 0.6 g of silicon nitride, and 10 g of N,N-dimethylformamide.

[0038] The preparation method of super-hydrophobic polyacrylonitrile fiber membrane comprises: 1.5 g of polyacrylonitrile, 0.6 g of (3-aminopropyl)triethoxysilane, 0.25 g of dodecyltriethoxysilane, 0.6 g of silicon nitride and 10 g of N,N-dimethylformamide were mixed, stirred at 280 rpm and 50°C for 12 h, and a superhydrophobic polyacrylonitrile fiber membrane was prepared by electrospinning.

[0039] The electrospinning parameters were as follows: electrospinning voltage of 22 kV, spinning distance of 16 cm, receiver rolling speed of 120 rpm, and electrospinning feed rate of 1.0 mL / h.

[0040] The water contact angle of the super-hydrophobic polyacrylonitrile fiber membrane obtained in this example was 159.1°, and the separation flux of the mixture of bromobenzene and water was higher than 4088 Lm -2 h -1 , the separation efficiency is above 98.8%; the separation flux of oil-in-water (bromobenzene-water) emulsion is higher than 692Lm -2 h -1 , separation efficiency is above 98.2% Example

[0041] This embodiment provides a super-hydrophobic polyacrylonitrile fiber membrane, comprising: 1.3 g of polyacrylonitrile, 0.75 g of (3-aminopropyl)triethoxysilane, 0.35 g of dodecyltriethoxysilane, 0.55 g of silicon carbide, and 10 g of N,N-dimethylformamide.

[0042] The preparation method of super-hydrophobic polyacrylonitrile fiber membrane comprises: 1.3 g of polyacrylonitrile, 0.75 g of (3-aminopropyl)triethoxysilane, 0.35 g of dodecyltriethoxysilane, 0.55 g of silicon carbide and 10 g of N,N-dimethylformamide were mixed, stirred at 280 rpm and 50°C for 12 h, and a superhydrophobic polyacrylonitrile fiber membrane was prepared by electrospinning.

[0043] The electrospinning parameters were as follows: electrospinning voltage of 22 kV, spinning distance of 16 cm, receiver rolling speed of 120 rpm, and electrospinning feed rate of 1.0 mL / h.

[0044] The water contact angle of the super-hydrophobic polyacrylonitrile fiber membrane obtained in this example is 158.6°, and the separation flux of the mixture of bromobenzene and water is higher than 4088 Lm -2 h -1 , the separation efficiency is above 98.8%; the separation flux of oil-in-water (bromobenzene-water) emulsion is higher than 692Lm -2 h -1 , the separation efficiency is above 98.2%.

[0045] Comparative Example 1 This comparative example provides a polyacrylonitrile fiber membrane, comprising: 1.3 g of polyacrylonitrile, 0.75 g of (3-aminopropyl)triethoxysilane, 0.35 g of dodecyltriethoxysilane, and 10 g of N,N-dimethylformamide.

[0046] The preparation method of the polyacrylonitrile fiber membrane comprises: 1.3 g of polyacrylonitrile, 0.75 g of (3-aminopropyl)triethoxysilane, 0.35 g of dodecyltriethoxysilane and 10 g of N,N-dimethylformamide were mixed, stirred at 290 rpm and 30°C for 12 h, and a polyacrylonitrile fiber membrane was prepared by electrospinning.

[0047] The electrospinning parameters were as follows: electrospinning voltage of 20 kV, spinning distance of 18 cm, receiver rolling speed of 120 rpm, and electrospinning feed rate of 1.0 mL / h.

[0048] The water contact angle of the polyacrylonitrile fiber membrane obtained in this comparative example is 150.4°, and the separation flux of the mixture of dichloromethane and water is higher than 3200 Lm -2 h -1 , the separation efficiency is above 98%; the separation flux of oil-in-water (dichloromethane-water) emulsion is higher than 430Lm -2 h -1 , the separation efficiency is above 97.1%.

[0049] Comparative Example 2 This comparative example provides a modified polyacrylonitrile fiber membrane, comprising: 1.1 g of polyacrylonitrile, 0.55 g of (3-aminopropyl)triethoxysilane, and 10 g of N,N-dimethylformamide.

[0050] The preparation method of the polyacrylonitrile fiber membrane comprises: 1.1 g of polyacrylonitrile, 0.55 g of (3-aminopropyl)triethoxysilane, and 10 g of N,N-dimethylformamide were mixed, stirred at 250 rpm and 40° C. for 12 h, and a polyacrylonitrile fiber membrane was prepared by electrospinning.

[0051] The electrospinning parameters were as follows: electrospinning voltage of 20 kV, spinning distance of 18 cm, receiver rolling speed of 120 rpm, and electrospinning feed rate of 1.0 mL / h.

[0052] The water contact angle of the polyacrylonitrile fiber membrane obtained in this comparative example is 144.2°, and the separation flux of the mixture of ethyl bromide and water is higher than 2800 Lm -2 h -1, the separation efficiency is above 97%; the separation flux of oil-in-water (bromoethane-water) emulsion is higher than 300Lm -2 h -1 , the separation efficiency is above 96.4%.

[0053] Comparative Example 3 This comparative example provides a pure polyacrylonitrile fiber membrane, comprising: 1.0 g of polyacrylonitrile and 10 g of N,N-dimethylformamide.

[0054] The preparation method of the polyacrylonitrile fiber membrane comprises: 1.0 g of polyacrylonitrile and 10 g of N,N-dimethylformamide were mixed, stirred at a speed of 250 rpm and a temperature of 30° C. for 12 h, and a polyacrylonitrile fiber membrane was prepared by electrospinning.

[0055] The electrospinning parameters were as follows: electrospinning voltage of 20 kV, spinning distance of 18 cm, receiver rolling speed of 120 rpm, and electrospinning feed rate of 1.0 mL / h.

[0056] The water contact angle of the polyacrylonitrile fiber membrane obtained in this comparative example is 124.5°, and the separation flux of the mixture of bromobenzene and water is higher than 2600 Lm -2 h -1 , the separation efficiency is above 97%; the separation flux of oil-in-water (bromobenzene-water) emulsion is higher than 320Lm -2 h -1 , the separation efficiency is above 92.6%.

[0057] Characterization testing The super-hydrophobic polyacrylonitrile fiber membranes prepared in Examples 1-3 and the polyacrylonitrile fiber membranes prepared in Comparative Examples 1-3 were observed by scanning electron microscopy. Figure 1 shown. Figure 1 (f) is the fiber membrane prepared in Comparative Example 3, and it can be found that the pure polyacrylonitrile fiber membrane has a cross-stacked fiber structure with a specific smooth fiber surface. Figure 1 (e) is the fiber membrane prepared in Comparative Example 2. Compared with Comparative Example 3, it can be seen that after (3-aminopropyl)triethoxysilane (APTES) is added to the polyacrylonitrile spinning solution, silicon-based particles appear on the fiber surface, which is attributed to the hydrolysis of APTES. Figure 1 (d) is the fiber membrane prepared in Comparative Example 1. Compared with Comparative Example 3, it can be seen that dodecyltriethoxysilane (DTMS) is added to the spinning solution of the above (Comparative Example 2) to prepare a modified polyacrylonitrile fiber membrane, which is characterized by irregular protrusions induced by co-hydrolysis. Figure 1(a)-(c) are super-hydrophobic polyacrylonitrile fiber membranes prepared in Examples 1-3, respectively. As can be seen from the figures, the silica particles are evenly distributed on the fiber matrix.

[0058] The super hydrophobic polyacrylonitrile fiber membrane prepared in Example 1 and the polyacrylonitrile fiber membrane prepared in Comparative Examples 1-3 were subjected to FTIR test. Figure 2 As shown. Figure 2 It can be seen that the pure polyacrylonitrile fiber membrane (Comparative Example 3) exhibits three prominent absorption peaks: 2850-2950 cm -1 (CH stretching in -CH2- group), 2242 cm -1 (-C≡N stretching) and 1452cm -1 (CH bending). After adding APTES, the modified polyacrylonitrile fiber membrane (Comparative Example 2) has a peak at 1553 cm -1 (NH bending), 1020-1200cm -1 (Si-O-Si tensile), 948cm -1 (Si-OH stretching) and 800 cm -1 A new absorption peak is shown at (Si-O-Si bending). 1553cm -1 The appearance of the peak confirmed the successful interaction of APTES-PAN. After further modification with APTES and DTMS, a modified polypropylene fiber membrane (Comparative Example 1) was obtained with a peak at 2850-2950 cm -1 The region showed a slight shift, which may be due to the long alkyl chain in DTMS. In addition, at 948 cm -1 The weakened Si-OH peak at the bottom indicates that the hydrolyzed DTMS and APTES polymerized through the Si-OH group, which indirectly verifies the DTMS grafting. For the super-hydrophobic polypropylene fiber membrane prepared in Example 1, the incorporation of silica particles did not produce new peaks, because the hydrolyzed APTES and DTMS generated alkylated silica with spectral characteristics similar to those of silica particles. Figure 1 The SEM scanning electron microscopy images in confirmed this observation, and found that the matrix of the modified superhydrophobic polypropylene fiber membrane was encapsulated with silica particles, which explains why the FTIR spectrum of the superhydrophobic polypropylene fiber membrane did not change compared with the modified polypropylene fiber membrane (Comparative Example 1).

[0059] The super-hydrophobic polyacrylonitrile fiber membranes prepared in Examples 1-3 and the polyacrylonitrile fiber membranes prepared in Comparative Examples 1-3 were subjected to water contact angle tests. Figure 3 shown. Figure 3 (f) Pure polyacrylonitrile fiber membrane prepared in Comparative Example 3 exhibits rapid droplet spreading and a water contact angle of 124.5±1.2°, indicating low inherent hydrophobicity. Figure 3(e) is the modified polyacrylonitrile fiber membrane prepared in Comparative Example 2. After functional modification with 3-aminopropyltriethoxysilane (APTES), the hydrophobicity of the polyacrylonitrile fiber membrane is significantly enhanced, and its water contact angle reaches 144.2±1.5°. Figure 3 (d) shows the modified polyacrylonitrile fiber membrane prepared in Comparative Example 1. Comparison with Comparative Example 2 reveals that further modification with the low-surface-energy hydrophobic modifier dodecyltrimethoxysilane (DTMS) increases the contact angle of the polyacrylonitrile fiber membrane to 150.4 ± 1.1°. This demonstrates that the combination of APTES and DTMS forms a hierarchical micro-nano-rough surface that traps air pockets to minimize the liquid-solid contact area, thereby inducing a Casse-Baxter state and enhancing hydrophobicity. Figure 3 (a)-(c) show the water contact angle measurements of the superhydrophobic polyacrylonitrile fiber membranes prepared in Examples 1-3, respectively. A comparison reveals that the static contact angles of the superhydrophobic polyacrylonitrile fiber membranes gradually increase with increasing amounts of the hydrophobic modifier and aminosilane covalent modifier (154.5±1.4°, 157.1±1.2°, and 161.3±1.6°, respectively). This increased hydrophobicity is associated with increased surface roughness, as larger silica particles protrude more prominently, amplifying structural heterogeneity and air retention.

[0060] Performance Testing The superhydrophobic polyacrylonitrile fiber membrane prepared in Example 1 was subjected to stability testing according to the following criteria. The mechanical stability of the membrane was evaluated by ultrasonicating the membrane for 60 minutes, collecting data every 10 minutes, followed by 30 tape stripping cycles (data collected after each cycle). Chemical resistance was assessed by immersing the membrane in organic solvents (ethanol, toluene, cyclohexane, n-hexane, petroleum ether, bromobenzene, and 1,2-dichloroethane) and aqueous solutions (pH 1-14) for 24 hours. After immersion, the surface was cleaned, dried, and analyzed for water contact angle (WCA). Aging resistance was tested by exposing the membrane to outdoor environmental conditions (wind, sunlight, and precipitation) for 30 days. During these 30 days, the maximum temperature was 35°C and the minimum temperature was 12°C. The UV radiation level was as high as 9°C. The ambient humidity ranged from 12% to 67%. This was accompanied by strong winds and dust storms. After exposure, the WCA measurement was repeated after the surface was cleaned and dried. Thermal stability was studied by heating the film in a muffle furnace for 1 hour at each temperature (50°C, 100°C, 150°C, 200°C, 250°C, and 300°C). The WCA value after each heat treatment was recorded to evaluate the temperature-dependent performance. Figure 4 shown. Figure 4(a) Mechanical stability test results. The results show that after 60 minutes of ultrasonic treatment, the superhydrophobic polyacrylonitrile fiber membrane provided by the present invention maintains a water contact angle above 160°, demonstrating excellent mechanical stability. This stability stems from the covalent bond between 3-aminopropyltriethoxysilane (APTES) and the polyacrylonitrile (PAN) matrix, which anchors the hydrophobic groups to the surface. Furthermore, the hydrolyzed silica particles form a durable composite coating, preventing particle shedding and maintaining surface roughness. Figure 4 (b) shows the tape stripping test results, further confirming the excellent mechanical stability of the superhydrophobic polyacrylonitrile fiber membrane provided by the present invention, maintaining its superhydrophobicity after 30 cycles. This is due to the uniform chemical composition between the surface and bulk phases, indicating that even surface damage does not affect the membrane's performance—a key advantage that most conventional surface-modified membranes cannot achieve. Figure 4 (c) is the pH immersion test result. The results show that the WCA value of the super-hydrophobic polyacrylonitrile fiber membrane provided by the present invention still exceeds 150° even after being exposed for 12 hours. Figure 4 (d) shows the results of the organic solvent immersion test. The results show that after 72 hours of exposure to organic solvents, the superhydrophobic polyacrylonitrile fiber membrane provided by the present invention maintained a water contact angle above 157.7°, maintaining oil-water separation efficiency, a key factor in long-term operational feasibility. Figure 4 (e) Thermal stability test results show that the water contact angle is higher than 155.4° at temperatures up to 300°C, confirming the structural integrity under thermal stress and excellent heat resistance. Figure 4 (f) shows the results of long-term environmental exposure testing. The results show that after 30 days of outdoor aging testing under ambient conditions, the WCA showed minimal fluctuation (161.1-158.6°) and an average of 160°, demonstrating excellent environmental durability. These tests demonstrate that the superhydrophobic polyacrylonitrile fiber membrane provided by the present invention possesses excellent mechanical stability, chemical inertness, thermal elasticity, and environmental durability—key attributes for sustainable superhydrophobic applications.

[0061] The super hydrophobic polyacrylonitrile fiber membrane prepared in Example 1 was subjected to wettability and anti-fouling tests. Figure 5 As shown. Figure 5 (a) It can be seen that the superhydrophobic polyacrylonitrile fiber membrane exhibits excellent liquid repellency: for more than 20 minutes, pure water and tea droplets maintain their spherical shape without diffusion or absorption. Figure 5 (b) It can be seen that in air, the membrane exhibits superoleophilicity, with an oil droplet contact angle of 0° and rapid penetration of the surface (< 1s), confirming its suitability for oil-phase dehydration applications. Crucially, the membrane maintains its superhydrophobicity even when immersed in oil. Figure 5(c) As can be seen, when the dyeing water is sprayed on the inclined superhydrophobic polyacrylonitrile fiber membrane surface, the liquid drops roll down without adhesion, ensuring effective hydrophobicity in the separation process and minimizing membrane fouling. Figure 5 (d) As can be seen, when hydrophilic soil particles are deposited on the surface thereof, they are wrapped by water drops after contact. By virtue of the non-wetting property of the membrane, these liquid drops quickly roll away, removing the attached pollutants and keeping the surface clean. It is illustrated that the superhydrophobic polyacrylonitrile fiber membrane provided by the present application has a self-cleaning function. The above test results, together with its strong anti-fouling ability, highlight the potential of the superhydrophobic polyacrylonitrile fiber membrane in an oil-water separation system, which requires high efficiency, durability and anti-fouling property.

[0062] Application Example The superhydrophobic polyacrylonitrile fiber membrane prepared in Example 1 was subjected to an oil-water separation comprehensive performance test according to the following standards.

[0063] A domestic filter device with an effective membrane area of 3.14 cm 2 was used to evaluate the effect of the superhydrophobic polyacrylonitrile fiber membrane on oil-water separation by a dead-end filter device. 10 mL of model oil was mixed with 10 mL of water to prepare an oil-water mixture. In order to more clearly observe the test process, the water phase and the oil phase were dyed with methylene blue and oil red O, respectively. Before introducing the oil-water mixture for separation, the membrane was pre-wetted with pure oil. The separation was carried out under the condition of gravity, and the time of the separation process and the amount of filtrate were monitored.

[0064] Separation flux = V / A·Δt; Separation efficiency (%) = (1-C1 / C0)×100%; Wherein, A is the membrane area (m 2 ), V is the permeation volume (L), Δt is the permeation time (h), C0 is the initial water content in the oil (ppm), C1 is the water content in the oil after separation (ppm), and the like. The water content was determined by Karl Fischer water meter. -2 h -1 ). The water content was determined by Karl Fischer water meter.

[0065] The ability of the superhydrophobic polyacrylonitrile fiber membrane to remove floating oil was tested.

[0066] The superhydrophobic polyacrylonitrile fiber membrane was folded and inserted into a rubber tube with a diameter of 2 mm, which was connected to the inlet of a micro peristaltic pump. The separation liquid was collected in a beaker at the outlet of the pump. The self-made oil-water mixture was poured into the beaker, and then the end of the rubber tube with the superhydrophobic polyacrylonitrile fiber membrane was placed above the oil-water interface to separate at a certain driving force (pump speed), so as to investigate the continuous separation ability of the material.

[0067] The oil-water separation performance of the superhydrophobic polyacrylonitrile fiber membrane was tested.

[0068] Mixtures of water and various model heavy oils (e.g., dichloromethane, 1,2-dichloroethane, bromobenzene, chlorobenzene, and ethyl bromide) were prepared. Figure 6 shown. Figure 6 (a) Schematic diagram of the oil-water separation process. After the mixture is introduced into the customized terminal filtration device, the water droplets initially contact and are repelled by the surface of the superhydrophobic polyacrylonitrile fiber membrane ( Figure 6 a-II). The oil droplet then penetrates the membrane by capillary action and quickly passes through the bottom of the device ( Figure 6 a-III), while water remains completely blocked ( Figure 6 a-VI). Post-separation analysis showed no cross-contamination: no oil or stained water were detected in the residual water above the membrane and the collected oil below the membrane, respectively, confirming the exceptional separation efficiency ( Figure 6 aV).

[0069] Figure 6 (b) is the oil absorption weight gain test chart. Figure 6 (b) It can be seen that the membrane is also effective for light oil-water mixtures. When low-density oil (stained with Oil Red O) is layered in water, the superhydrophobic polyacrylonitrile fiber membrane quickly adsorbs the floating oil upon contact. After removal, no oil remains in the water, indicating that the membrane exhibits selective absorption and does not absorb water ( Figure 6 b-IV). The weight of the water remained unchanged, further verifying the purity retention.

[0070] Figure 6 (c) is a comparison chart of oil-water mixture separation flux / efficiency of different models. The separation flux and separation efficiency are calculated by the above formula. Figure 6 (c) It can be seen that the flux values ​​of dichloromethane-water, 1,2-dichloroethane-water, bromobenzene-water, chlorobenzene-water, and bromoethane-water mixtures are 3921, 3668, 4177, 3761, and 4068 L m -2 h -1 , all efficiencies exceeded 98.8%.

[0071] Figure 6 (d) shows the cycling stability test graph. The weight gain percentage was determined by calculating the membrane weight before and after adsorption using the separation efficiency formula described above, ranging from 609% (n-hexane) to 1707% (bromobenzene). Comparing the density and viscosity of different model oils, materials with higher density and viscosity exhibited higher weight gain percentages after adsorption, indicating that the adsorption weight gain is related to the density or viscosity of the oil. After 10 cycles of testing, the weight efficiency of the superhydrophobic polyacrylonitrile fiber membrane remained stable (change ≤7%), demonstrating excellent cycling durability.

[0072] Figure 6(e) is a schematic diagram of the continuous oil absorption-desorption separation device, in which the superhydrophobic polyacrylonitrile fiber membrane is integrated into the peristaltic pump system. Figure 6 (e) As can be seen, the superhydrophobic polyacrylonitrile fiber membrane continuously absorbs oil from the oil-water mixture to obtain pure oil without water contamination, highlighting the potential for large-scale leak remediation. This system provides a reliable technical solution for efficient and continuous oil-water separation in practical applications.

[0073] The super hydrophobic polyacrylonitrile fiber membrane prepared in Example 1 was subjected to a comprehensive test of the water-in-oil emulsion separation performance. Figure 7 shown.

[0074] Figure 7 (a) Schematic diagram of oil-in-water emulsion separation, where the prepared n-hexane / water emulsion (green) is introduced into a custom-made separation device. Figure 7 (a) It can be seen that when in contact with the superhydrophobic polyacrylonitrile fiber membrane, the emulsion droplets rupture, allowing n-hexane to permeate the membrane while water is retained.

[0075] Figure 7 (b) Schematic diagram of digital microscope and optical microscope before and after separation. Figure 7 (b) It can be seen that there are no water droplets in the filtrate, demonstrating the effectiveness of the superhydrophobic polyacrylonitrile fiber membrane in emulsion separation.

[0076] Figure 7 (c) is a comparison chart of the separation flux and efficiency of different types of oil-in-water emulsions. Figure 7 (c) It can be seen that the separation fluxes and yields of toluene, cyclohexane, n-hexane, dichloromethane, 1,2-dichloroethane, and bromobenzene in oil-in-water emulsion are 618, 611, 621, 685, 679, and 709 L m, respectively. -2 h -1 The water content in the filtrate was determined by Karl Fischer titration, and the separation efficiency was calculated using the above formula, confirming that the efficiency of all emulsions exceeded 98.2%.

[0077] Figure 7 (d) and (e) Cyclic stability test images. After each cycle, the membrane was regenerated by washing with ethanol and drying at 60 °C. Figure 7 (d) and (e) show that after 10 cycles, the flux of 1,2-dichloroethane emulsion increased from 679 L m -2 h -1 A slight decrease to 632 L m -2 h -1 The water contact angle (WCA) measured after the cycle remained at around 159°, confirming the integrity of the structure.

[0078] Figure 7 (f) is a graph showing the long-term separation stability and regeneration performance test, which simulates the industrial applicability of this method by monitoring the flux during the long-term separation of 1,2-dichloroethane / water emulsion. Figure 7 (f) As can be seen, the initial flux (682 L m⁻² h⁻¹) decreased by 44.72% after 15 min due to contamination, but the efficiency remained high (97.1%). Ethanol cleaning resulted in a flux recovery of 94.28% and an efficiency of 98.3%, demonstrating strong regeneration capabilities.

[0079] The above test results highlight the potential of the superhydrophobic polyacrylonitrile fiber membrane provided by the present invention in industrial applications, including marine oil spill remediation and automotive oil purification, due to its high efficiency, stability and scalability.

[0080] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A super-hydrophobic polyacrylonitrile fiber membrane, characterized in that: Contains the following raw materials in parts by weight: 1-1.5 parts of polyacrylonitrile, 0.1-1.5 parts of aminosilane covalent modifier, 0.1-0.8 parts of hydrophobic modifier, 0.1-1.5 parts of nanoparticles, and 9-11 parts of solvent.

2. The super-hydrophobic polyacrylonitrile fiber membrane according to claim 1, characterized in that The aminosilane covalent modifier includes one or more of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, 3-aminopropylmethyldimethoxysilane, bis(3-aminopropyl)dimethoxysilane, 3-aminopropyltriisopropoxysilane, (2-aminoethyl)trimethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldiethoxysilane and 3-aminobutyltrimethoxysilane.

3. The super-hydrophobic polyacrylonitrile fiber membrane according to claim 1, characterized in that The hydrophobic modifier includes one or more of methyltrimethoxysilane, methyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane and hexadecyltriethoxysilane.

4. The super-hydrophobic polyacrylonitrile fiber membrane according to claim 1, characterized in that The nanoparticles include one or more of silicon dioxide, titanium dioxide, silicon nitride and silicon carbide.

5. The super-hydrophobic polyacrylonitrile fiber membrane according to claim 1, characterized in that The solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, acetonitrile, acetone and tetrahydrofuran.

6. The method for preparing the super-hydrophobic polyacrylonitrile fiber membrane according to any one of claims 1 to 5, characterized in that: The steps include: The super-hydrophobic polyacrylonitrile fiber membrane is obtained by mixing polyacrylonitrile, an aminosilane covalent modifier, a hydrophobic modifier, nanoparticles and a solvent and performing electrostatic spinning.

7. The method for preparing a super-hydrophobic polyacrylonitrile fiber membrane according to claim 6, wherein: The mixing time is 6-24 hours, the mixing stirring rate is 100-350 rpm, and the mixing temperature is 25-60°C.

8. The method for preparing a super-hydrophobic polyacrylonitrile fiber membrane according to claim 6, wherein: The voltage of the electrostatic spinning is 15-30 kV, and the distance of the electrostatic spinning is 12-25 cm.

9. The method for preparing a super-hydrophobic polyacrylonitrile fiber membrane according to claim 6, wherein: The rolling speed of the electrospinning receiver is 40-350 rpm, and the feeding rate of the electrospinning is 0.8-2.5 mL / h.

10. Use of the super-hydrophobic polyacrylonitrile fiber membrane according to any one of claims 1 to 5 or the super-hydrophobic polyacrylonitrile fiber membrane prepared by the method for preparing the super-hydrophobic polyacrylonitrile fiber membrane according to any one of claims 6 to 9 in oil-water separation.

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