CN107754493B - Photocatalytic transparent PM2.5 filtering membrane and preparation method thereof - Google Patents

Abstract

The invention discloses a photocatalytic transparent PM2.5 filter membrane and a preparation method thereof. The PM2.5 filter membrane is a composite nanofiber membrane of a sandwich-like structure, including polyacrylonitrile@ _TiO2 and polyamide-6, The nanofiber diameter distribution of the composite nanofiber membrane is 60-100 nm. The composite membrane is closely cross-linked, and has photocatalytic function, high transparency and efficient PM2.5 filtration performance. When used in anti-nano screen windows, it can not only effectively block outdoor PM2.5 from entering the room, but also under the action of sunlight. Photocatalyzes low-concentration harmful gases in the atmosphere while maintaining good lighting and ventilation effects.

Description

A kind of transparent PM2.5 filter membrane with photocatalysis and preparation method thereof

technical field

The invention belongs to the technical field of filter material preparation, in particular to a photocatalytic transparent PM2.5 high-efficiency filter membrane and a preparation method thereof.

Background technique

With the development of industrialization, the pollution of the environment and air is further intensified, and the harm caused by PM2.5 has attracted worldwide attention. PM2.5 is called "particulate matter that can enter the lungs", which can directly enter the lungs of people. Because it contains toxic and harmful substances, and it stays in the air for a long time and has a long transportation distance, it will inevitably affect the quality of the atmospheric environment and human health. Negative impact. In addition, indoor air quality has also attracted people's attention. Especially during the severe haze period, the PM2.5 value in indoor air is even higher than that in outdoor air. At the same time, the concentration of indoor VOCs caused by interior decoration increases significantly, which seriously affects people's health. . Therefore, the research and development of high-efficiency PM2.5 filter materials with high-efficiency degradation of VOCs in the air has received extensive attention. Wu Rui et al. prepared an anti-PM2.5 nano-screen with photocatalytic function, the screen is composed of nano air filtration membrane, photocatalytic membrane and carbon sandwich non-woven fabric, wherein the nano air filtration membrane is made of dispersed nano vinegar. It is composed of fiber filaments, forming many nano-pores with pore diameters of 0.5-1 μm, and the porosity of the nano-filtration membrane is 85%-98%; the photocatalytic membrane is composed of TiO2/SiO2 composite nanotubes. The nano-screen screen is composed of a photocatalytic membrane and a nano-filtration membrane with filtration performance. The preparation process has a relatively long process flow, and the nano-acetate cellulose has a large pore size, and the PM2.5 filtration efficiency is only about 75%, and Transparency is not high.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a photocatalytic transparent PM2.5 filter membrane and a preparation method thereof, aiming at the deficiencies in the above-mentioned prior art, so as to improve the low light transmittance and poor air permeability of the existing air filter membrane. And the problem of single function is suitable for indoor air purification devices and window screen materials and other fields.

The present invention adopts following technical scheme:

A transparent PM2.5 filter membrane with photocatalytic activity, the PM2.5 filter membrane is a composite nanofiber membrane of a sandwich-like structure, including polyacrylonitrile @ _TiO2 and polyamide-6, and the polyamide-6 is arranged in The upper and lower layers of the sandwich-like structure, polyacrylonitrile@TiO ₂ is arranged in the middle layer of the sandwich-like structure, and the nanofiber diameter distribution of the composite nanofiber membrane is 60-100 nm.

Further, the porosity of the polyacrylonitrile@TiO ₂ is 80-85%, and the surface pore size is 0.05-0.1 μm.

Further, the light transmittance of the composite nanofiber membrane is 70-75%, and the air permeability is 14450-14912 mL/(cm ² ·h).

A preparation method of a photocatalytic transparent PM2.5 filter membrane, comprising the following steps:

S1. Respectively prepare a PAN@TiO ₂ spinning solution with a mass percentage of 6-10% and a polyamide-6 spinning solution with a mass percentage of 12-16%, wherein the PAN@TiO ₂ spinning solution is doped with There is TiO ₂ with a mass fraction of 20%;

S2. The PAN@TiO ₂ spinning solution and the polyamide-6 spinning solution prepared in step S1 are respectively injected into the two liquid storage cylinders of the spinning nozzle in the electrospinning machine, and the spinning nozzle is set on the electrospinning machine to receive On the left side of the device, the flow rate of the spinning solution is controlled by a syringe pump, tin foil is set on the receiving device of the electrospinning machine, and then the single-needle spinning is started to spin the different polymers in the liquid storage cylinder respectively, and the surface of the receiving device is spun. A uniform and transparent PAN@TiO ₂ /PA6 nanocomposite fiber film was obtained;

S3. The PAN@TiO ₂ /PA6 nanocomposite fiber membrane obtained in step S2 is vacuum-dried at 60° C. for 18 h to 24 h together with tin foil to obtain a transparent PM2.5 filter membrane with a photocatalytic sandwich-like structure.

Further, in step S1, the polyacrylonitrile powder is slowly added to the N,N-dimethylformamide solution, magnetically stirred at 20 to 25°C for 8 to 12 hours, and then slowly added with nano-titania powder TiO ₂ , and the temperature is continued at 20 to 25°C. After stirring for 8 to 12 h, a PAN@TiO ₂ spinning solution with a mass fraction of 6% to 10% of the total spinning solution was prepared.

Further, the molecular weight of the polyacrylonitrile powder is 150,000, and the average particle size of the nano titanium dioxide powder is 40-50 nm.

Further, in step S1, the polyamide-6 particles are dissolved in a formic acid solution, and magnetically stirred at 25° C. for 18-24 hours until the polyamide-6 particles are completely dissolved, and the polyamide-6 spinning with a mass percentage of 12-16% is prepared. liquid, spare.

Further, the molecular weight of the polyamide-6 particles is 18,000-20,000.

Further, in step S2, firstly open the polyamide-6 spinning solution for spinning, collect for 20-30 minutes to obtain a layer of polyamide-6 nanofiber membrane as a substrate; then open the PAN/TiO ₂ spinning solution for spinning, Collect for 15-20 minutes; finally turn on the polyamide-6 spinning solution for spinning, and collect for 20-30 minutes.

Further, the spinning voltage is 18-20 kV, the spinning distance is 18-20 cm, and the liquid feeding speed is 0.5-0.8 mL/h.

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

The invention is a transparent PM2.5 filter membrane with photocatalytic activity, and a composite nano air filter with a sandwich-like structure composed of polyacrylonitrile/ _TiO2 nanofibers and polyamide-6 nanofibers is obtained by a simple electrospinning method. Material, the composite membrane is closely cross-linked, and has photocatalytic function, high transparency and efficient PM2.5 filtration performance. Applied in anti-nano screen windows, it can not only effectively block outdoor PM2.5 from entering the room, but also in the sunlight. Under the action of photocatalysis, low concentration harmful gases in the atmosphere are maintained, while maintaining good lighting and ventilation effects.

Further, the porosity of polyacrylonitrile@TiO ₂ is 80-85%, the average surface pore size is 0.05-0.1 μm, the specific area is large, the porosity is high, the filtration rate of PM2.5 in the air is high, the transparency is high, and the air permeability is high. Good performance.

Further, the light transmittance of the composite nanofiber membrane is 70-75%, the air permeability is 14450mL/(cm ² ·h)～14912mL/(cm ² ·h), and it has good filtering performance, high light transmittance and air permeability. Well, the filtration efficiency of PM2.5 in the air is 97.97% to 99.89%, and it has a good photocatalytic effect on indoor VOCs.

The invention also discloses a method for preparing a transparent PM2.5 filter membrane with photocatalysis, respectively preparing a PAN@ _TiO2 spinning solution and a polyamide-6 spinning solution, and then spinning through a double-needle electrospinning machine silk to obtain a uniform and transparent PAN@TiO ₂ /PA6 nanocomposite fiber membrane, and finally vacuum-dried at 60 °C for 18-24 h to obtain a transparent PM2.5 filter membrane with a sandwich-like structure with photocatalytic activity. It is easy to implement, and the prepared PM2.5 filter membrane also has the functions of being transparent, efficiently filtering PM2.5, and photocatalytically degrading VOCs.

Further, in this method, hydrophilic nano-TiO ₂ is directly added to the PAN spinning solution, the configuration process is simple and easy, and the prepared PAN@TiO ₂ spinning solution is homogeneous and transparent, and has stable properties.

Further, in this method, the PA6 particles are directly dissolved in a formic acid solvent, and a homogeneous and transparent PA6 spinning solution can be obtained by stirring at 25° C. for a certain period of time. The method is simple and easy to implement and the raw materials are readily available.

Further, in this method, alternate spinning is performed by a double-needle spinning machine, and the spinning times of different pipeline needles are respectively controlled. First, PA6 spinning is started, and the spinning is collected for 20 to 30 minutes, and then the PAN/TiO2 spinning solution is started. Spinning and collecting for 15min-20min, finally turning on polyamide-6 spinning, spinning and collecting for 20min-30min, the obtained nanofiber filter membrane has good light transmittance and filtering effect.

Further, when the spinning voltage is 18-20kV, the spinning distance is 18-20cm, and the liquid feeding speed is 0.5mL/h-0.8mL/h, the spinning process is stable, and the average diameter of the obtained nanofibers is smaller, The pore size is small, the porosity is high, the thickness of the obtained nanofiber membrane is uniform, and the performance is stable.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the schematic diagram of the electrostatic spinning machine device of the preparation method of the present invention;

2 is a scanning electron microscope image of the composite nanofiber air filtration membrane obtained in Example 3 of the present invention.

Among them: 1. High voltage power supply; 2. Syringe; 3. Micro dual-channel syringe pump; 4. Spinneret; 5. Receiving device.

Detailed ways

The invention discloses a transparent PM2.5 filter membrane with photocatalysis. The PM2.5 filter membrane is a composite nanofiber membrane with a sandwich-like structure, which are polyamide-6 and polyacrylonitrile@ _TiO2 in order from top to bottom. And polyamide-6, PM2.5 filter membrane is PAN@TiO ₂ /PA6 composite nanofiber membrane, and its nanofiber diameter distribution is 60nm～100nm.

Among them, the light transmittance of the PAN@TiO ₂ /PA6 composite nanofiber membrane is 70%-75%, the air permeability is 14450mL/(cm ² ·h)~14912mL/(cm ² ·h), and the porosity is 80%~ About 85%, the surface pore size is 0.05 ~ 0.1μm.

The invention also discloses a method for preparing a photocatalytic transparent PM2.5 filter membrane, comprising the following steps:

S1. Respectively prepare a PAN@TiO ₂ spinning solution with a mass percentage of 6% to 10% and a polyamide 6 spinning solution with a mass percentage of 12% to 16%, wherein the PAN@TiO ₂ spinning solution is mixed with 20% TiO ₂ by mass fraction;

Among them, polyacrylonitrile powder (PAN) was slowly added to the N,N-dimethylformamide (DMF) solution, magnetically stirred at 25°C for 8-12 h, and then nano titanium dioxide powder (TiO ₂ ) was slowly added to the solution, Continue to stir at 25°C for 8-12 h to prepare PAN@TiO ₂ spinning solution with a mass fraction of 6%-10%;

Preferably, the molecular weight of polyacrylonitrile is 150,000, and the average particle size of the hydrophilic nano-TiO ₂ is 40nm-50nm;

Dissolve polyamide-6 particles (PA6) in formic acid solution, stir magnetically at 25°C for 18-24 hours until polyamide-6 particles are completely dissolved, and prepare polyamide-6 (PA6) spinning with a mass percentage of 12%-16% liquid, spare;

Preferably, the molecular weight of the polyamide-6 is 18,000-20,000.

S2. Inject the PAN@TiO ₂ and PA6 spinning solutions into the two liquid storage cylinders of the spinning nozzle of the electrospinning machine respectively, set the spinning nozzle on the left side of the receiving device of the electrospinning machine, and control the spinning solution through a syringe pump Set the tin foil on the receiving device of the electrospinning machine, and then start the single-needle spinning to spin different polymers in the liquid storage cylinder respectively, and a layer of uniform and transparent PAN@TiO can be obtained on the surface of the receiving device. ₂ /PA6-like sandwich structure nanocomposite fiber membrane;

Among them, firstly open the PA6 spinning solution for spinning, and collect for 20min-30min; then open the PAN/ _TiO2 spinning solution for spinning, and collect for 15min-20min; then open the PA6 spinning solution for spinning, and collect for 20min-30min;

Preferably, the spinning voltage is 18-20 kV, the spinning distance is 18-20 cm, and the liquid feeding speed is 0.5 mL/h-0.8 mL/h.

S3. The PAN@TiO ₂ /PA6 nanocomposite fiber film obtained in step S2 is vacuum-dried together with tin foil at 60° C. for 18h-24h to obtain PAN@TiO ₂ /PA6 composite nanofibers with a sandwich-like structure and stable performance. PM2.5 filter material.

Example 1:

S1, spinning solution preparation

Weigh 3g of polyacrylonitrile powder (PAN), 0.6g of nano-titanium dioxide powder (TiO ₂ ), 47g of N,N-dimethylformamide (DMF) respectively, slowly add the PAN powder to the DMF solution, magnetic force at 25°C Stir for 8 h, then slowly add nano-TiO ₂ to the solution, continue stirring at 25 °C for 8 h, and prepare a PAN@TiO ₂ spinning solution with a mass fraction of 6%; weigh 6 g of polyamide-6 particles (PA6) and dissolve it in 44 g of formic acid solution was magnetically stirred at 25° C. for 18 h until the PA6 particles were completely dissolved, and a PA6 spinning solution with a mass percentage of 12% was prepared for use.

Preparation of S2 and PAN@TiO ₂ /PA6 composite nanofibers

The above-mentioned PAN@TiO ₂ spinning solution and PA6 spinning solution are respectively injected into the two liquid storage cylinders of the syringe 2 in the micro-injection pump 3, the tin foil is placed on the receiving device 5, the high-voltage power supply 1 is started, the spinneret 4 Start working (as shown in Figure 1).

First turn on the PA6 spinning solution for spinning, the spinning voltage is 18KV, the spinning distance is 18cm, the feeding speed of the spinning solution is 0.5mL/h, and the collection is 30min; then the PAN/ _TiO2 spinning solution is turned on for spinning, adjusting The spinning voltage was 20KV, the spinning distance was 18cm, the feeding speed of the spinning solution was 0.5mL/h, and the collection was 15min; finally, the PA6 spinning solution was turned on for spinning, the spinning voltage was 18KV, the spinning distance was 18cm, and the spinning solution was The feeding rate is 0.5mL/h, and the collection is 30min;

Post-processing of S3, PAN@TiO ₂ /PA6 composite nanofibers

After shutdown, the obtained PAN@TiO ₂ /PA6 composite electrospinning fiber membrane and tin foil were vacuum-dried at 60 °C for 24 h to fully volatilize the solvent, and the PAN@TiO ₂ /PA6 composite nanometer with a sandwich-like structure and stable performance was obtained. Fiber PM2.5 filter material.

The PAN@TiO ₂ /PA6 composite nanofiber membrane is closely cross-linked in network, with an average nanofiber diameter of 70 nm, a porosity of 80%, an average surface pore size of 0.06 μm, and a filtration efficiency of 97.97% for PM2.5 in the air. The light transmittance is 72%, the air permeability is 14688mL/(cm ² ·h), and it has a good photocatalytic effect on indoor VOCs.

Example 2:

S1, spinning solution preparation

Weigh 4g of polyacrylonitrile powder (PAN), 0.8g of nano titanium dioxide powder (TiO ₂ ), and 46g of N,N-dimethylformamide (DMF), respectively. The PAN powder was slowly added to the DMF solution, magnetically stirred at 25 °C for 12 h, then nano-TiO ₂ was slowly added to the solution, and stirred at 25 °C for 12 h to prepare a PAN@TiO ₂ spinning solution with a mass fraction of 8%; Dissolve 7g of polyamide-6 particles (PA6) in 43g of formic acid solution, stir magnetically at 25°C for 24h until the PA6 particles are completely dissolved, and prepare a PA6 spinning solution with a mass percentage of 14%.

Preparation of S2 and PAN@TiO ₂ /PA6 composite nanofibers

The above-mentioned PAN@TiO ₂ spinning solution and PA6 spinning solution are respectively injected into the two liquid storage cylinders of the syringe 2 in the micro-injection pump 3, the tin foil is placed on the receiving device 5, the high-voltage power supply 1 is started, the spinneret 4 Start working (as shown in Figure 1).

First turn on the PA6 spinning solution for spinning, the spinning voltage is 20KV, the spinning distance is 20cm, the feeding speed of the spinning solution is 0.6mL/h, and the collection is 20min; then the polyacrylonitrile/TiO ₂ blended spinning solution is turned on for spinning silk, the spinning voltage was 20KV, the spinning distance was 18cm, the feeding speed of the spinning solution was 0.6mL/h, and the collection was 10min; finally, the PA6 spinning solution was turned on for spinning, the spinning voltage was 20KV, the spinning distance was 20cm, and the spinning was performed. The feeding speed of silk liquid is 0.6mL/h, and the collection is 20min;

Post-processing of S3, PAN@TiO ₂ /PA6 composite nanofibers

After shutdown, the obtained composite electrospinning fiber membrane and tin foil were vacuum-dried at 60 °C for 24 h to fully volatilize the solvent, and the PAN@TiO ₂ /PA6 composite nanofiber PM2.5 filter material with a sandwich-like structure and stable performance was obtained. .

The PAN@TiO ₂ /PA6 composite nanofiber membrane is closely cross-linked in network, with an average nanofiber diameter of 60 nm, a porosity of 83%, an average surface pore size of 0.1 μm, and a filtration efficiency of 98.89% for PM2.5 in the air. The light transmittance is 75%, the air permeability is 14912mL/(cm ² ·h), and it has a good photocatalytic effect on indoor VOCs.

Example 3:

S1, spinning solution preparation

5 g of polyacrylonitrile powder (PAN), 1 g of nano-titanium dioxide powder (TiO ₂ ), and 45 g of N,N-dimethylformamide (DMF) were weighed respectively. The PAN powder was slowly added to the DMF solution, magnetically stirred at 25 °C for 12 h, then nano-TiO ₂ was slowly added to the solution, and stirred at 25 °C for 12 h to prepare a PAN@TiO2 spinning solution with a mass fraction of 10%; 8 g of polyamide-6 particles (PA6) were dissolved in 42 g of formic acid solution, and magnetically stirred at 25° C. for 24 h until the PA6 particles were completely dissolved, to prepare a PA6 spinning solution with a mass percentage of 16%.

Preparation of S2 and PAN@TiO ₂ /PA6 composite nanofibers

The above-mentioned PAN@TiO ₂ and the polyamide-6 spinning solution are respectively injected into the two liquid storage cylinders of the syringe 2 in the micro-syringe pump 3, the tin foil paper is placed on the receiving device 5, the high-voltage power supply 1 is started, the spinneret 4 Start working (as shown in Figure 1).

First turn on the polyamide-6 spinning solution for spinning, the spinning voltage is 20KV, the spinning distance is 20cm, the feeding speed of the spinning solution is 0.8mL/h, and the collection is 20min; then the PAN/TiO ₂ blended spinning solution is turned on to carry out Spinning, the spinning voltage is 20KV, the spinning distance is 20cm, the feeding speed of the spinning solution is 0.5mL/h, and the collection is 10min; finally, the polyamide-6 spinning solution is turned on for spinning, the spinning voltage is 20KV, and the spinning is performed. The distance is 20cm, the feeding speed of the spinning solution is 0.8mL/h, and the collection is 20min;

Post-processing of S3, PAN@TiO ₂ /PA6 composite nanofibers

After shutdown, the obtained composite electrospinning fiber membrane and tin foil were vacuum-dried at 60 °C for 24 h to fully volatilize the solvent, and the PAN@TiO ₂ /PA6 composite nanofiber PM2.5 filter material with a sandwich-like structure and stable performance was obtained. .

The PAN@TiO ₂ /PA6 composite nanofiber membrane is closely cross-linked in network, with an average nanofiber diameter of 100 nm, a porosity of 85%, an average pore size of 0.05 μm, and a filtration efficiency of 99.89% for PM2.5 in the air. The light rate is 70%, the air permeability is 14450mL/(cm ² ·h), and it has a good photocatalytic effect on indoor VOCs.

Table 1 is the comparison before and after the effect of the composite nanofiber air filter material of Example 3 on several indoor Vocs

The scanning electron microscope image of the PAN@TiO ₂ /PA6 composite nanofiber membrane obtained in Example 3 is shown in Figure 2. In the figure, the nanofibers are closely cross-linked, the average diameter is 100 nm, the porosity is 85%, and the average pore size is 0.05μm.

The above content is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any modification made on the basis of the technical solution proposed in accordance with the technical idea of the present invention falls within the scope of the claims of the present invention. within the scope of protection.

Claims (4)

1. a preparation method of a photocatalytic transparent PM2.5 filter membrane is characterized in that, the PM2.5 filter membrane is a composite nanofiber membrane of a sandwich-like structure, comprising polyacrylonitrile@TiO ₂ and polyamide-6 , polyamide-6 is arranged in the upper and lower layers of the sandwich-like structure, polyacrylonitrile@TiO ₂ is arranged in the middle layer of the sandwich-like structure, and the nanofiber diameter distribution of the composite nanofiber membrane is 60-100 nm. The porosity of TiO ₂ is 80-85%, the surface pore size is 0.05-0.1 μm, the light transmittance of the composite nanofiber membrane is 70-75%, and the air permeability is 14450-14912 mL/(cm ² ·h), including The following steps: S1. Prepare a PAN@TiO ₂ spinning solution and a polyamide-6 spinning solution respectively, wherein the PAN@TiO ₂ spinning solution is doped with TiO ₂ that accounts for 20% of the mass percentage of the PAN@TiO ₂ spinning solution , slowly add the polyacrylonitrile powder to the N,N-dimethylformamide solution, stir magnetically at 20-25°C for 8-12h, then slowly add nano-titanium dioxide powder TiO ₂ , continue stirring at 20-25°C for 8-12h, to prepare To obtain a PAN@ _TiO2 spinning solution with a mass fraction of 6% to 10% of the total spinning solution, the polyamide-6 particles are dissolved in formic acid solution, and magnetically stirred at 25 ° C for 18 to 24 hours until the polyamide-6 particles are completely dissolved. Preparation A polyamide-6 spinning solution with a mass percentage of 12-16% is obtained, which is used for later use; S2. The PAN@TiO ₂ spinning solution and the polyamide-6 spinning solution prepared in step S1 are respectively injected into the two liquid storage cylinders of the spinning nozzle of the electrospinning machine, and the spinning nozzle is set on the receiving device of the electrospinning machine. On one side, the flow rate of the spinning solution is controlled by a syringe pump, and tin foil is set on the receiving device of the electrospinning machine, and then the single-needle spinning is started to spin the different polymers in the liquid storage cylinder respectively, and the surface of the receiving device is obtained. A layer of uniform and transparent PAN@TiO ₂ /PA6 nanocomposite fiber membrane, firstly open the polyamide-6 spinning solution for spinning, collect for 20-30min to obtain a layer of polyamide-6 nanofiber membrane as the substrate; then open the PAN/ The TiO ₂ spinning solution is spun and collected for 15-20 min; finally, the polyamide-6 spinning solution is turned on for spinning and collected for 20-30 min; S3. The PAN@TiO ₂ /PA6 nanocomposite fiber membrane obtained in step S2 is vacuum-dried at 60° C. for 18 h to 24 h together with tin foil to obtain a transparent PM2.5 filter membrane with a photocatalytic sandwich-like structure. 2. The method for preparing a photocatalytic transparent PM2.5 filter membrane according to claim 1, wherein in step S1, the molecular weight of the polyacrylonitrile powder is 150,000, and the nano-titanium dioxide powder has a molecular weight of 150,000. The average particle size is 40 to 50 nm. 3 . The method for preparing a photocatalytic transparent PM2.5 filter membrane according to claim 1 , wherein in step S1 , the molecular weight of the polyamide-6 particles is 18,000-20,000. 4 . 4. The preparation method of a photocatalytic transparent PM2.5 filter membrane according to claim 1, wherein in step S2, the spinning voltage is 18-20kV, and the spinning distance is 18-20cm, The feeding rate is 0.5 to 0.8 mL/h.

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