CN107158969B - A functionalized nanofiber filter material and its preparation method and application - Google Patents

Abstract

The invention discloses a functionalized nanofiber filter material, a preparation method and application thereof, and belongs to the technical field of air purification materials. The method includes the following steps: adding C ₃ N ₄ nanosheets into a solvent, ultrasonically oscillating to disperse uniformly, then adding polymer powder to dissolve uniformly, to obtain a polymer spinning solution containing C _{3 N4} nanosheets, and mixing the obtained polymer The spinning solution is prepared on the substrate by electrospinning technology to obtain the functionalized nanofiber filter material; the functionalized nanofiber filter material obtained by the present invention can well filter organic pollutants, and when used as an air filter material, the high efficiency and low resistance, greatly improving air quality.

Description

A functionalized nanofiber filter material and its preparation method and application

technical field

The invention belongs to the technical field of air purification materials, and in particular relates to a functionalized nanofiber filter material and a preparation method and application thereof.

Background technique

Air pollution seriously affects people's health, life, work and social economy. Filtration technology is an effective way to improve the atmospheric environment and improve indoor quality. At present, ordinary air filter materials have low efficiency and high resistance, which cannot meet people's requirements for air quality. It is urgent to develop a functional air filter material that can filter particulate matter with high efficiency and low resistance and can remove air pollutants such as formaldehyde.

Electrospinning nanofiber filter material, due to its sparse porous structure and relatively high specific surface area, has the most superior performance among many filter materials. However, because they are generally spun from high polymers, most of them can only intercept and electrostatically adsorb suspended particles in the air, but cannot remove bacteria, viruses and organic pollutants in the air. In recent years, many experts and scholars have prepared various composite functionalized electrospun nanofiber membranes by compounding electrospun nanofibers with functionalized materials.

The CN 103446803A invention patent disclosed in China on December 18, 2013 introduces an antibacterial air filter felt and its preparation method and application. The invention uses an electrospun polymer nanofiber felt as a carrier material and is loaded by electrostatic spraying There is a certain concentration of nano-antibacterial agent, and the nano-antibacterial agent is selected from nano-silver anti-bacterial agent. When preparing, first prepare nano-silver antibacterial agent suspension and polymer spinning solution, and then use electrospinning to prepare nano-fiber felt synchronous electrostatic spraying load nano-antibacterial agent. agent, and finally vacuum dried. The disadvantage of this technology is that the nano antibacterial agent is selected from nano silver antibacterial agent, although it can play a role in sterilization, but the heavy metal silver in it will cause inevitable harm to the human body.

The CN 104785018A invention patent published in China on July 22, 2015 introduces a PVDF nanofiber functionalized air filter material and a preparation method thereof. It includes a polypropylene microfiber layer and a PVDF nanofiber layer. PVDF nanofibers are made from spinning solution, which uses polypropylene microfiber layer as base material, mixes PVDF resin, mixed solvent and tetrabutyl perchloric acid with hinge stirring, heat presses the base material through high temperature calender roll, and then It is sent to the electrospinning device for spraying. The disadvantage of this technology is that this filter material only contains two materials: PVDF and polypropylene, and has no special sterilization and oily particle adsorption functions, and the production process is complicated and the cost is high.

The CN104815483A invention patent published in China on August 5, 2015 introduces a composite antibacterial air filter material, which includes an electret fabric layer, an electrospinning fiber membrane layer and a base material non-woven layer that are bonded in sequence. The surfaces of the electrospun fiber film layer and the substrate non-woven layer are loaded with chitosan and nano-TiO ₂ photocatalysts. Although this method can play the functions of antibacterial, disinfection and deodorization, the production process is too complicated, and the spray coating is easy to fall off.

SUMMARY OF THE INVENTION

In order to solve the above shortcomings and deficiencies of the prior art, for the removal of organic pollutants such as formaldehyde, the primary purpose of the present invention is to provide a functionalized nanofiber filter material.

Another object of the present invention is to provide a method for preparing a functionalized nanofiber filter material.

Another object of the present invention is to illustrate the application of the functionalized nanofiber filter material.

The purpose of the present invention is achieved through the following technical solutions.

A preparation method of functionalized nanofiber filter material, comprising the following steps:

(1) Preparation of polymer spinning solution: adding C ₃ N ₄ nanosheets into a solvent, ultrasonically oscillating until the dispersion is uniform, then adding a polymer, stirring magnetically until uniformly dissolving, to obtain a polymer containing C _{3 N4} nanosheets spinning solution;

(2) Electrospinning: the polymer spinning solution obtained in step (1) is prepared on a substrate by electrospinning technology to obtain a functionalized nanofiber filter material.

Preferably, the ultrasonic oscillation time in step (1) is 1 h.

Preferably, the time of magnetic stirring in step (1) is 12h.

Preferably, the solvent in step (1) is one or more of formic acid, N-N dimethylformamide, tetrahydrofuran, trifluoroacetic acid, dichloromethane, water and acetone.

Preferably, the polymer in step (1) is polyamide, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyurethane, polyvinyl chloride, polystyrene, poly At least one of acrylonitrile, polyvinyl alcohol and polylactic acid.

Further preferably, the polymer and solvent described in step (1) are respectively as follows:

Polyamide: formic acid solvent;

Polycarbonate: a mixed solvent of N-N dimethylformamide and tetrahydrofuran with a mass ratio of 1:1;

Polyethylene terephthalate: a mixed solvent of trifluoroacetic acid and dichloromethane with a volume ratio of 4:1;

Polybutylene terephthalate: a mixed solvent of trifluoroacetic acid and dichloromethane with a volume ratio of 3:2;

Polyurethane: a mixed solvent of N-N dimethylformamide and tetrahydrofuran with a mass ratio of 7:3;

Polyvinyl chloride: a mixed solvent of N-N dimethylformamide and tetrahydrofuran with a mass ratio of 1:1;

Polystyrene: N-N dimethylformamide solvent;

Polyacrylonitrile: N-N dimethylformamide solvent;

Polyvinyl alcohol: water solvent;

Polylactic acid: a mixed solvent of N,N-dimethylformamide and acetone with a mass ratio of 4:1.

Preferably, the content of C ₃ N ₄ nanosheets in the polymer spinning solution in step (1) is 0.01-20 wt.%.

Preferably, the content of the polymer in the polymer spinning solution in step (1) is 5-25 wt.%.

Preferably, the substrate in step (2) is a conventional microfiber filter material.

Preferably, the electrospinning process conditions of step (2) are: voltage 10-30 kV, receiving distance 5-30 cm, injection speed 1-5 mL/h, temperature 0-35°C, and relative humidity 0-70%.

A functionalized nanofiber filter material prepared by the method described above.

Preferably, the material is composed of a nanofiber membrane and a substrate, the nanofiber membrane is composed of a class of general engineering plastic polymer nanofibers and C ₃ N ₄ nanosheets dispersed in the polymer nanofibers; the C ₃ N _4. The nanosheet is prepared from melamine by high temperature thermal exfoliation; the fiber diameter of the nanofiber membrane is 100-900 nm, the gram weight of the nanofiber membrane is 0.01-5 g/m ² , and the porosity is ≥80%.

Application of the above-mentioned functionalized nanofiber filter material in air filtration.

The invention innovatively introduces C ₃ N ₄ nanosheets on the surface of the nanofibers. C ₃ N ₄ is a non-metallic semiconductor material, which is composed of C and N elements that are abundant in the earth, and is resistant to corrosion by acid, alkali and light. , good stability, hardness comparable to diamond, structure and properties easy to control. C ₃ N ₄ is a layered structure of graphite phase, gas molecules can pass between the layers, and there are many defects ranging from 0.3nm to tens of nanometers inside, which is conducive to the passage of gas and can greatly reduce the PM2.5 separation process. pressure drop, improving filtration efficiency during air purification. In addition, C ₃ N ₄ itself has a certain amino group (NH), which has a good adsorption and separation effect on air pollutants such as formaldehyde, CO, and nitrogen oxides.

The functionalized nanofiber filter material obtained by the present invention can be applied to industrial dust filtration systems, indoor air filtration (such as air purifier filter elements and air conditioner filter elements, etc.), vehicle gas filtration systems (such as vehicle air purifiers and exhaust gas filtration) It can also be used as screens, curtains, door curtains, etc., and can also be used to make protective clothing and masks.

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

(1) The present invention adds C ₃ N ₄ nanosheets to the electrospinning polymer nanofibers for the first time to obtain a functionalized nanofiber filter material;

(2) The C ₃ N ₄ nanosheets added to the functionalized nanofiber filter material of the present invention do not contain metal and have good biocompatibility. Due to its own unique layered structure, defects and amino groups, the When used as an air filter material, it can not only effectively intercept suspended particles in the air, but also adsorb nitrogen oxides, CO, SO ₂ and other chemical pollutants, especially organic dyes in the air (methylene blue, methyl orange and Rhodane). Ming B, etc.) and small molecular compounds (formaldehyde, phenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, decabromodiphenyl ether, acetaldehyde, NO and Cr, etc.) also have good filtration It can greatly improve the air purification effect. In addition, due to its ultra-high hardness, the mechanical strength of the nanofiber membrane can be well improved. Its own defects can effectively increase the specific surface area of the filter material and reduce the pressure drop, greatly increasing its adsorption capacity and improving the filtration efficiency. .

(3) The C ₃ N ₄ nanosheets used in the present invention, due to its unique two-dimensional material properties and its unique amino group, synergize with the polymer itself when it is added to the spinning fiber. Particulate pollutants and organic pollutants such as formaldehyde have a more efficient separation effect.

(4) The preparation method of the functionalized nanofiber filter material of the present invention is simple, does not require special devices and equipment, and can be applied to the preparation of a wide range of nanofiber membrane filter materials;

(5) The functionalized nanofiber filter material of the present invention is widely used and has a good application prospect.

Description of drawings

FIG. 1 is a schematic structural diagram of the electrospinning equipment used in the present invention.

Figure 2 is a schematic diagram of the structure and function of the functionalized nanofiber filter material obtained in the present invention.

FIG. 3 is a schematic diagram of a test device when the functionalized nanofiber filter material obtained in the present invention is subjected to a filtration test.

4 is a scanning electron microscope (SEM) image of the functionalized polyvinylidene fluoride+C ₃ N ₄ nanofiber filter material obtained in the present invention.

Figure 5a is an atomic force microscope (AFM) image of the C ₃ N ₄ nanosheets used in the present invention.

Figure 5b is a thickness analysis diagram of the C ₃ N ₄ nanosheets used in the present invention.

6 is a comparison diagram of the filtration efficiency of the functionalized polyvinylidene fluoride+C ₃ N ₄ nanofiber filter material obtained in Example 3 of the present invention and the addition of other substances.

7 is a graph showing the filtration efficiency of the functionalized polyvinylidene fluoride+C ₃ N ₄ nanofiber filter material obtained in Example 3 of the present invention for formaldehyde and carbon monoxide.

Detailed ways

The present invention will be described in further detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

FIG. 1 is a schematic structural diagram of an electrospinning device used in the present invention, which includes a flat plate receiver 1 , a bolus injection system 2 of the electrospinning device, and an electrostatic high voltage supply system 3 .

2 is a schematic diagram of the structure and function of the functionalized nanofiber filter material obtained in the present invention, the material includes a functionalized nanofiber layer 4 , a base layer 5 , nanofibers 6 and C ₃ N ₄ nanosheets 7 .

3 is a schematic diagram of a test device when the functionalized nanofiber filter material obtained in the present invention is subjected to a filtration test. The device includes a detector 8 , an airflow inlet 9 , an airflow outlet 10 , a chamber 11 , and a membrane material 12 .

Example 1

A preparation method of functionalized nanofiber filter material, the specific steps are:

(1) The polylactic acid (PLA) was dried in a vacuum oven at 60° C. for 2 h. Accurately weigh _14.235g N _- N dimethylformamide with an electronic balance and place it in a 25ml beaker, then weigh 0.015g C3N4 nanosheets (the atomic force microscope image and thickness analysis of the nanosheets are shown in Figures 5a and 5b). (shown) placed in NN dimethylformamide, ultrasonically vibrated for 6h, take out the beaker, accurately weigh 0.75g of dried polylactic acid powder with an electronic balance and place it in the beaker, stir magnetically at room temperature for 24h, and prepare uniform and stable of polyacrylonitrile spinning solution containing _{C3N4 nanosheets} .

(2) The spinning solution obtained in step (1) is prepared on the substrate by electrospinning technology, and the electrospinning equipment shown in FIG. 1 is used for electrospinning. , stick on the plate receiver, adjust the electrospinning parameters, the translation speed of the bolus system is 120mm/min, the receiving distance is 30cm, the electrostatic high voltage is 25kV, the bolus speed is 2mL/h, the temperature is 25℃, the relative humidity is 70% to obtain a functionalized nanofiber filter material, namely functionalized polylactic acid+C ₃ N ₄ nanofiber filter material, the fiber diameter of the nanofiber membrane in the obtained material is 500nm, the gram weight is 0.05g/m ² , and the porosity is 85%.

The schematic diagram of the structure and function of the functionalized nanofiber filter material obtained in this example is shown in FIG. 2 , and the scanning electron microscope image of the obtained functionalized nanofiber filter material is shown in FIG. 4 .

Example 2

A preparation method of functionalized nanofiber filter material, the specific steps are:

(1) The polyvinyl chloride (PVC) powder was dried in a vacuum oven at 60°C for 2 hours. Use an electronic balance to accurately weigh _5.625g NN dimethylformamide and _5.625g tetrahydrofuran into a 50ml beaker, and then weigh 1.5g C3N4 nanosheets (the atomic force microscope image and thickness analysis of the nanosheets are shown in Figure 5a. and 5b), placed in the above mixed solvent, oscillated with an ultrasonic oscillator for 6h, took out the beaker, accurately weighed 2.25g of dried polyvinyl chloride powder with an electronic balance and placed it in the beaker, and magnetically stirred at room temperature for 24h, It was formulated into a uniform and stable polyvinyl chloride spinning solution containing C ₃ N ₄ nanosheets.

(2) The spinning solution obtained in step (1) is prepared on the substrate by electrospinning technology, and the electrospinning equipment shown in FIG. 1 is used for electrospinning. , stick on the plate receiver, adjust the electrospinning parameters, the translation speed of the bolus system is 120mm/min, the receiving distance is 30cm, the electrostatic high voltage is 30kV, the bolus speed is 2mL/h, the temperature is 15℃, the relative humidity is 25% to obtain functionalized nanofiber filter material, namely functionalized polyvinyl chloride+C ₃ N ₄ nanofiber filter material, the fiber diameter of nanofiber membrane in the obtained material is 300nm, the gram weight is 2g/m ² , and the porosity is 80%, the SEM image is similar to Figure 4.

The schematic diagram of the structure and function of the functionalized nanofiber filter material obtained in this example is shown in FIG. 2 .

Example 3

A preparation method of functionalized nanofiber filter material, the specific steps are:

(1) The polyvinylidene fluoride (PVDF) powder was dried in a vacuum oven at 60° C. for 2 h. Accurately weigh _{8.25g of} NN dimethylformamide into a 50ml beaker with an electronic balance, and then weigh 3g of C3N4 nanosheets (the atomic force microscope image and thickness analysis of the nanosheets are shown in Figures 5a and 5b) In the above solvent, vibrate with an ultrasonic oscillator for 5 hours, take out the beaker, accurately weigh 3.75g of dried polyvinylidene fluoride powder with an electronic balance and place it in the beaker, stir magnetically at room temperature for 24 hours, and prepare a uniform and stable containing Polyvinylidene fluoride spinning solution _{of C3N4} nanosheets.

(2) The spinning solution obtained in step (1) is prepared on the substrate by electrospinning technology, and the electrospinning equipment shown in FIG. 1 is used for electrospinning. , stick on the flat receiver, adjust the electrospinning parameters, the translation speed of the bolus system is 100mm/min, the receiving distance is 30cm, the electrostatic high voltage is 30kV, the bolus speed is 2mL/h, the temperature is 20℃, the relative humidity is 20% to obtain a functionalized nanofiber filter material, namely functionalized polyvinylidene fluoride+C ₃ N ₄ nanofiber filter material, the fiber diameter of the nanofiber membrane in the obtained material is 450nm, and the gram weight is 0.01g/m ² , The porosity is 95%, and the SEM image is similar to Figure 4.

The schematic diagram of the structure and function of the functionalized nanofiber filter material obtained in this example is shown in FIG. 2 .

The functionalized nanofiber filter materials obtained in Examples 1, 2, and 3 are used as the filtration performance test test of air filter materials:

There are two sources of polluted air used by the device, one is cigarette smoke, and the other is burning smoke from plant materials. It has been confirmed that PM (suspended particulate matter) contained in cigarette smoke has a particle size ranging from 0.01-10 μm, and it contains about 7000 different chemicals, most of which are harmful formaldehyde

(HCHO) and CO pollutants. Combustion smoke from plant material also contains a large particle size range of PM and high concentrations of formaldehyde (HCHO) and CO pollutants. After the polluted air was diluted to a measurable level, it was passed into the left chamber of the experimental device, and the polluted air was monitored by a particle counter (CEM, DT-9881). At the same time, under the control of the air flow rate of 5.33 cm/s, a pressure gauge (UEi, EM201-B) was used to measure the pressure difference of the air flow of the filter membrane. The filter membrane was cut into a circle with a diameter of 10 cm, and was clamped by a clamp for filtration testing. The filtration efficiency η of the filter membrane can be expressed as

η=((C ₀ -C ₁ ))/C ₀

where: _C0 represents the amount of air pollutants in the left chamber,

C ₁ represents the amount of air pollutants in the right chamber.

The experimental results show that the functionalized nanofiber filter materials obtained in Examples 1, 2, and 3 are used as air filter materials to filter PM in the air with a filtration efficiency of more than 95%, and the filtration pressure drop is between 10 and 50Pa. The results of Example 3 As shown in Figure 6 (the preparation methods of PVDF+silicon dioxide, PVDF+barium titanate, and PVDF materials in Figure 6 are the same as those in Example 3, except that carbon nitride is changed to silicon dioxide and barium titanate). The filtration efficiency for formaldehyde (HCHO) and CO reaches 60-80%, and the results of Example 3 are shown in FIG. 7 .

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (5)

1. A functional nanofiber air filter material is characterized in that,

the functionalized nanofiber air filter material consists of a nanofiber membrane and a substrate, wherein the nanofiber membrane consists of polymer nanofibers and C dispersed in the polymer nanofibers₃N₄Nano-sheet composition; the nanofiber membrane has the fiber diameter of 100-900 nm and the gram weight of 0.01-5 g/m²The porosity is more than or equal to 80 percent;

the functionalized nanofiber air filter material is prepared by the following method:

(1) preparing a polymer spinning solution: c is to be₃N₄Adding the nanosheets into a solvent, performing ultrasonic oscillation until the nanosheets are uniformly dispersed, adding a polymer, and performing magnetic stirring until the nanosheets are uniformly dissolved to obtain the C-containing material₃N₄A polymer spinning solution of nanosheets;

(2) electrostatic spinning: preparing the polymer spinning solution obtained in the step (1) on a substrate by an electrostatic spinning technology to obtain a functionalized nanofiber filtering material;

c in the polymer spinning solution in the step (1)₃N₄The content of the nanosheets is 0.01-20 wt.%;

the content of the polymer in the polymer spinning solution in the step (1) is 5-25 wt.%.

2. The functionalized nanofiber air filter material of claim 1, wherein the solvent of step (1) is one or two of formic acid, N-N dimethylformamide, tetrahydrofuran, trifluoroacetic acid, dichloromethane, water and acetone.

3. The functionalized nanofiber air filter material of claim 1, wherein the polymer of step (1) is at least one of polyamide, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyurethane, polyvinyl chloride, polystyrene, polyacrylonitrile, polyvinyl alcohol, and polylactic acid.

4. The functionalized nanofiber air filter material of claim 1, wherein the polymer and the solvent of step (1) correspond to the following:

polyamide: a formic acid solvent;

polycarbonate (C): a mixed solvent of N-N dimethylformamide and tetrahydrofuran in a mass ratio of 1: 1;

polyethylene terephthalate: a mixed solvent of trifluoroacetic acid and dichloromethane in a volume ratio of 4: 1;

polybutylene terephthalate: a mixed solvent of trifluoroacetic acid and dichloromethane in a volume ratio of 3: 2;

polyurethane: a mixed solvent of N-N dimethylformamide and tetrahydrofuran in a mass ratio of 7: 3;

polyvinyl chloride: a mixed solvent of N-N dimethylformamide and tetrahydrofuran in a mass ratio of 1: 1;

polystyrene: N-N dimethylformamide solvent;

polyacrylonitrile: N-N dimethylformamide solvent;

polyvinyl alcohol: a water solvent;

polylactic acid: a mixed solvent of N, N-dimethylformamide and acetone in a mass ratio of 4: 1.

5. The functionalized nanofiber air filter material as claimed in claim 1, wherein the electrostatic spinning in step (2) is carried out under the following process conditions: the voltage is 10-30 kV, the receiving distance is 5-30 cm, the injection speed is 1-5 mL/h, the temperature is 0-35 ℃, and the relative humidity is 0-70%.

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