A method for constructing a PAN-PVC porous hollow nanofiber felt by blending electrospinning

Abstract

The application discloses a method for constructing PAN-PVC porous hollow nanofiber felt through blending electrospinning. Polyacrylonitrile and polyvinyl chloride are dissolved in N-N dimethylacetamide to obtain PAN / PVC precursor spinning solution; the PAN / PVC precursor spinning solution is electrospun to obtain fibers; the fibers are heated to 220-280 DEG C, pre-oxidized for 0.8-2 h, and then placed in a tubular furnace, heated to 800-1100 DEG C under N2 atmosphere, and kept at a constant temperature for 1-3 h to obtain PAN / PVC porous hollow nanofiber felt. The application directly obtains the porous hollow carbon nanofiber adsorbent with high adsorption performance based on blending electrospinning and carbonization, utilizes the phase separation characteristics of specific polymers to obtain the porous hollow carbon nanofiber adsorbent with high adsorption performance, and the prepared adsorbent does not need a traditional activation process, can have high adsorption capacity for target pollutants cyclopyracycline, and realizes efficient adsorption and removal of the target antibiotic.

Description

Technical Field

[0001] This invention belongs to the field of adsorption materials, specifically relating to a method for constructing PAN-PVC porous hollow nanofiber mats by blending electrospinning. Background Technology

[0002] Pharmaceuticals and personal care products (PPCPs) constitute a large category of emerging pollutants in the environment. PPCPs are broadly categorized, including antibiotics, hormones, painkillers, as well as cosmetics, hair dyes, and detergents used in daily life. While the widespread use of PPCPs serves humanity, it also poses a significant threat to environmental safety and human health. Antibiotics, in particular, are widely used in medicine due to their effectiveness in treating diseases caused by viruses, bacteria, and other microorganisms. Most antibiotics have complex structures and exhibit high chemical stability, high biological activity, and bioaccumulation. Even trace levels of antibiotics in the environment can accelerate the proliferation of antibiotic-resistant bacteria and the emergence of resistance genes. Therefore, researching efficient methods for removing antibiotics from water bodies is of significant practical importance.

[0003] Adsorption is a method that utilizes porous solid materials to adsorb and remove one or more substances from wastewater. It has a wide range of applications and significant effects, and is suitable for treating organic dye wastewater. Due to its advantages such as simple operation, low cost, high adsorption capacity, and no toxic byproducts, adsorption is considered one of the most promising methods for removing pollutants from wastewater. Currently, commonly used adsorbents include molecular sieves, natural minerals, polymers, carbon-based materials, and metal-organic frameworks (MOFs). Among these, carbon-based materials have attracted widespread attention due to their abundant and inexpensive raw material sources, stable physicochemical properties, high specific surface area, and well-developed pore structure. Given the ease of spinning and high carbon yield of polyacrylonitrile (PAN), current research on carbon-based nanofiber materials mainly focuses on PAN-based carbon nanofibers. However, PAN-based nanofibers obtained by simple carbonization have low specific surface area and pore volume, usually requiring further activation to achieve a specific surface area comparable to other carbon materials such as activated carbon. This increases costs to some extent and limits their application.

[0004] Currently, the preparation of porous carbon typically requires complex preparation conditions and additional activators, templates, and dopants, resulting in high costs and environmental unfriendliness. The selection of precursors and additives, as well as the design of preparation schemes, are among the challenges in achieving high-performance, low-cost porous carbon. In general, the current preparation of porous carbon suffers from the following drawbacks: 1. Most porous carbon precursors have a single structural composition and high cost; 2. After carbonization, residual templates or activators are generally removed using acidic or alkaline reagents; 3. The introduction of heteroatoms generally requires additional dopants, and the doping effect depends on the dispersion of the dopant in the precursor and the strict control of doping conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a method for constructing PAN-PVC porous hollow nanofiber felt by blending electrospinning.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for constructing PAN-PVC porous hollow nanofiber mat by blend electrospinning includes the following steps:

[0008] 1) Dissolve 1-2 g of polyacrylonitrile (PAN) and 1-3 g of polyvinyl chloride (PVC) in 15-30 mL of NN dimethylacetamide (DMAC), and stir magnetically for 8-24 hours to obtain PAN / PVC precursor spinning solution;

[0009] 2) Take 15 mL of PAN / PVC precursor spinning solution and transfer it to a 20 mL syringe equipped with a No. 21 stainless steel needle. Use a roller covered with aluminum foil as a collecting device. The distance between the needle and the roller is 15-30 cm. Apply a positive voltage of 15-25 kV to the needle and a negative voltage of 0.3-1 kV to the collecting roller. Keep the roller rotation speed at 200-500 r / min and the syringe push speed at 1-3 mL / h to collect the fibers obtained by electrospinning.

[0010] 3) The collected fibers are heated to 220-280 °C in an oven at a heating rate of 5-10 °C / min for 0.8-2 h to obtain pre-oxidized nanofiber mat. The pre-oxidized nanofiber mat is then placed in a tube furnace and heated at 5-10 °C / min under a N2 atmosphere. -1 The temperature was increased to 800~1100 ℃ at a heating rate and held at that temperature for 1~3 h to obtain PAN / PVC porous hollow nanofiber felt.

[0011] Preferably, the mass ratio of polyacrylonitrile to polyvinyl chloride is 1:1 to 1:3.

[0012] This invention utilizes polymer blending and electrospinning to prepare PAN-PVC composite nanofiber mats, and then prepares PAN-PVC porous hollow nanofiber mats via a one-step carbonization method. Based on the microphase separation between polymers in the mixed solution, carbon nanofiber mats with porous hollow structures are obtained when the mass ratio of PAN to PVC is 1:1 to 1:3.

[0013] The present invention has the following advantages:

[0014] 1. This invention uses the addition of pore-forming agent polymer PVC to the spinning solution, followed by high-temperature pyrolysis, to achieve the preparation of porous carbon nanofibers in one step. As a pore-forming agent, polymer PVC is basically completely decomposed and removed during the carbonization process, providing hollow channels and abundant pores for the PAN-derived carbon nanofiber skeleton. The hollow channels provide a faster mass transfer rate for molecular diffusion.

[0015] 2. This invention is based on the direct preparation of porous hollow carbon nanofiber adsorbents with high adsorption performance through blending electrospinning combined with carbonization. By utilizing the phase separation characteristics of specific polymers, porous hollow carbon nanofiber adsorbents with high adsorption performance are obtained. The prepared adsorbent does not require traditional activation processes and can have a high adsorption capacity for the target pollutant ciprofloxacin, thus achieving efficient adsorption and removal of the target antibiotic. Attached Figure Description

[0016] Figure 1 This is a microstructure diagram of the PAN-PVC carbon nanofiber felt synthesized by the method of this invention.

[0017] Figure 2 These are the nitrogen adsorption-desorption curves of PAN and PAN-PVC carbon nanofiber felts.

[0018] Figure 3 This is a diagram showing the adsorption effect of PAN and PAN-PVC carbon nanofiber felt on ciprofloxacin. Implementation Example 1

[0019] A method for constructing PAN-PVC porous hollow nanofiber mat by blend electrospinning includes the following steps:

[0020] 1) Dissolve 1 g of polyacrylonitrile (PAN) and 2 g of polyvinyl chloride (PVC) in 25 mL of NN dimethylacetamide (DMAC) and stir magnetically for 16 hours to obtain PAN / PVC precursor spinning solution;

[0021] 2) Take 15 mL of PAN / PVC precursor spinning solution and transfer it to a 20 mL syringe equipped with a No. 21 stainless steel needle. Use a roller covered with aluminum foil as the collecting device. The distance between the needle and the roller is 25 cm. Apply a positive voltage of 20 kV to the needle and a negative voltage of 0.6 kV to the collecting roller. Keep the roller rotation speed at 350 r / min and the syringe push speed at 2.0 mL / h to collect the fibers obtained by electrospinning.

[0022] 3) The collected fibers were heated to 250 °C in an oven at a heating rate of 10 °C / min for 1.0 h to obtain pre-oxidized nanofiber mat. The pre-oxidized nanofiber mat was then placed in a tube furnace and heated at 5 °C / min under a N2 atmosphere. -1 The temperature was increased to 900 °C at a certain rate and held at that temperature for 1.5 h to obtain PAN / PVC porous hollow nanofiber felt.

[0023] The microstructure of the synthesized PAN-PVC carbon nanofiber felt in this embodiment is as follows: Figure 1 As shown.

[0024] Nitrogen adsorption-desorption curves of PAN and PAN-PVC carbon nanofiber felt are as follows: Figure 2 As shown, from Figure 2 It can be seen that the addition of porous PVC significantly increases the specific surface area of ​​the material, from 459.28 m² / g for pure PAN to 843.34 m² / g for the composite. This increase in specific surface area helps improve the material's removal of target pollutants. Example 2

[0025] A method for constructing PAN-PVC porous hollow nanofiber mat by blend electrospinning includes the following steps:

[0026] 1) Dissolve 1 g of polyacrylonitrile (PAN) and 3 g of polyvinyl chloride (PVC) in 30 mL of NN dimethylacetamide (DMAC) and stir magnetically for 8 hours to obtain PAN / PVC precursor spinning solution;

[0027] 2) Take 15 mL of PAN / PVC precursor spinning solution and transfer it to a 20 mL syringe equipped with a No. 21 stainless steel needle. Use a roller covered with aluminum foil as the collecting device. The distance between the needle and the roller is 15 cm. Apply a positive voltage of 15 kV to the needle and a negative voltage of 0.3 kV to the collecting roller. Keep the roller speed at 200 r / min and the syringe push speed at 1.5 mL / h to collect the fibers obtained by electrospinning.

[0028] 3) The collected fibers were heated to 240 °C in an oven at a heating rate of 9 °C / min for 1.2 h to obtain pre-oxidized nanofiber mat. The pre-oxidized nanofiber mat was then placed in a tube furnace and heated at 5 °C / min under a N2 atmosphere. -1 The temperature was increased to 800 °C at a certain rate and held at that temperature for 2 h to obtain PAN / PVC porous hollow nanofiber felt. Example 3

[0029] A method for constructing PAN-PVC porous hollow nanofiber mat by blend electrospinning includes the following steps:

[0030] 1) Dissolve 1 g of polyacrylonitrile (PAN) and 1 g of polyvinyl chloride (PVC) in 15 mL of NN dimethylacetamide (DMAC) and stir magnetically for 24 hours to obtain PAN / PVC precursor spinning solution;

[0031] 2) Take 15 mL of PAN / PVC precursor spinning solution and transfer it to a 20 mL syringe equipped with a No. 21 stainless steel needle. Use a roller covered with aluminum foil as the collecting device. The distance between the needle and the roller is 30 cm. Apply a positive voltage of 25 kV to the needle and a negative voltage of 1 kV to the collecting roller. Keep the roller speed at 500 r / min and the syringe push speed at 2.5 mL / h to collect the fibers obtained by electrospinning.

[0032] 3) The collected fibers were heated to 280 °C in an oven at a heating rate of 10 °C / min for 1.2 h to obtain pre-oxidized nanofiber mat. The pre-oxidized nanofiber mat was then placed in a tube furnace and heated at 5 °C / min under a N2 atmosphere. -1 The temperature was increased to 1000 °C at a certain rate and held at that temperature for 1 h to obtain PAN / PVC porous hollow nanofiber felt. Example 4

[0033] Adsorption performance test of PAN / PVC porous hollow nanofiber felt

[0034] The adsorption performance of PAN / PVC porous hollow nanofiber mat was evaluated by adsorbing ciprofloxacin solution in a simulated natural water environment.

[0035] The initial concentration of ciprofloxacin was 20 ppm. Before the reaction began, 0.01 g of adsorbent (PAN or PAN / PVC porous hollow nanofiber mat) was dispersed in a blue-capped bottle containing 100 mL of ciprofloxacin solution. The entire adsorption process was carried out in a constant temperature water bath with a stirrer. 3 mL of the suspension was drawn with a syringe according to the time gradient, centrifuged, and the absorbance of the solution was measured using a UV spectrophotometer to calculate the degradation efficiency of the sample.

[0036] The adsorption effects of PAN and PAN-PVC carbon nanofiber felt on ciprofloxacin are as follows: Figure 3 As shown. From Figure 3 It can be seen that, compared with PAN, PAN-PVC carbon nanofiber felt has a better adsorption capacity for ciprofloxacin, indicating that the PAN-PVC carbon nanofiber felt prepared in this invention can effectively remove pollutants remaining in natural water environments.

Claims

1. A method for constructing PAN-PVC porous hollow nanofiber mat by blend electrospinning, characterized in that, The PAN-PVC porous hollow nanofiber felt is used to adsorb ciprofloxacin, and the method includes the following steps: 1) Dissolve polyacrylonitrile and polyvinyl chloride in N,N dimethylacetamide and stir magnetically until homogeneous to obtain PAN / PVC precursor spinning solution; 2) Take the PAN / PVC precursor spinning solution and transfer it to a 20 mL syringe equipped with a No. 21 stainless steel needle. Use a roller covered with aluminum foil as the collecting device. The distance between the needle and the roller is 15-30 cm. Apply a positive voltage of 15-25 kV to the needle and a negative voltage of 0.3-1 kV to the collecting roller. Keep the roller rotation speed at 200-500 r / min and the syringe push speed at 1-3 mL / h to collect the fibers obtained by electrospinning. 3) In an oven, the collected fibers are heated to 220~280 ℃ and pre-oxidized for 0.8~2 h to obtain pre-oxidized nanofiber felt; 4) Place the pre-oxidized nanofiber felt in a tube furnace and heat it to 800~1100 ℃ under N2 atmosphere, and keep it at the temperature for 1~3h. Based on the microphase separation between polymers in the mixed solution, when the mass ratio of PAN to PVC is 1:1~1:3, PAN / PVC porous hollow nanofiber felt is obtained.

2. The method for constructing PAN-PVC porous hollow nanofiber mat by blending electrospinning according to claim 1, characterized in that, The ratio of N,N-dimethylacetamide, polyacrylonitrile, and polyvinyl chloride is 15-30 mL: 1-2 g: 1-3 g.

3. The method for constructing PAN-PVC porous hollow nanofiber mat by blending electrospinning according to claim 1, characterized in that, The stirring time in step 1) is 8-24 hours.

4. The method for constructing PAN-PVC porous hollow nanofiber mat by blending electrospinning according to claim 1, characterized in that, The heating rate in step 3) is 5~10 ℃ / min.

5. The method for constructing PAN-PVC porous hollow nanofiber mat by blending electrospinning according to claim 1, characterized in that, The heating rate in step 4) is 5~10 °C·min. -1 .

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