TWI759225B - Preparation method of needle-type cerium dioxide photocatalyst and its use, and a preparation method of filter material containing the photocatalyst - Google Patents

Abstract

A preparation method of needle-type cerium dioxide photocatalyst and its use, and a preparation method of filter material containing the photocatalyst, the needle-type cerium dioxide photocatalyst prepared by such a method has high specific surface area and photocatalytic capability and can effectively degrade volatile organic compounds, the needle-type cerium dioxide photocatalyst is applied to the preparation method of the filter material by electrostatic spinning technology, so as to produce the filter material containing the needle-type cerium dioxide photocatalyst and being used for filtering particles and photodegradation of volatile organic compounds.

Description

Preparation method and application of needle-shaped ceria photocatalyst, preparation method and application of filter material containing the photocatalyst

The present invention relates to the technical field of photocatalyst, in particular to the preparation method and use of a pointer type ceria photocatalyst, as well as the preparation method and use of a filter material containing the needle type ceria photocatalyst.

With the vigorous development of industry and commerce today, it has driven the economy and living environment standards, but it has also caused environmental damage, and then faced the impact of pollution of the living environment. Air pollution has become one of the main ways for the human body to come into contact with atmospheric pollutants and cause health hazards. . Among them, particulate pollutants and volatile organic compounds (VOCs) are the two most frequently exposed pollutants in the air. And due to the increase in the application of nanotechnology in recent years, the opportunities for people to be exposed to nanometer and submicron particles have increased, so many studies have begun to focus on the filtration of nanometer particles; and VOCs are harmful to human health. , and even carcinogenic, which is in great need of high-efficiency technology to remove.

At present, there are many technologies for treating VOCs, including absorption method, condensation method, adsorption method, thermal incineration method, biological treatment method and photocatalytic method, etc. However, most of the current treatment technologies generally have some problems, such as low efficiency, Disadvantages such as high cost and high energy consumption. Then, it is worth noting that photocatalytic degradation of VOCs is currently known to be widely used due to the advantages of energy saving, low toxicity, and low cost. In addition, the separation technology of particles is known such as electrostatic precipitator, cyclone dust collector, wet scrubbing method, filtration, etc., among which, the use of filtration method to remove particulate pollutants has the advantages of low cost, simple operation and production, etc. , is the most commonly used air purification method at present, and its application fields are wide, including respiratory protective equipment, air purifiers, clean rooms and so on.

To sum up, the inventor of the present application believes that it is necessary to propose a filter material containing a photocatalyst capable of filtering particulates and photodegrading VOCs, and its preparation method and application.

In order to overcome the above-mentioned technical problems, the object of the present invention is to provide a method for making a needle-type ceria photocatalyst and its application, a method for making a filter material containing the photocatalyst and its application, and the present invention obtains through the method for making the needle-type ceria photocatalyst. A photocatalyst with high specific surface area and photocatalytic ability, which can effectively degrade volatile organic compounds (VOCs), and the photocatalyst is applied to the production method of filter material by electrospinning technology to obtain the filter material containing needle-shaped ceria photocatalyst , the filter material is used to filter particles and degrade VOCs through the needle-shaped ceria photocatalyst combined in the fiber tissue. The filter material of the invention has a particle filtration efficiency of more than 99.5% and a VOCs degradation efficiency of more than 95.0% by combining with ceria. Thereby, the filter material prepared by the present invention is formed by adding needle-shaped ceria photocatalyst to have both filtering and photocatalytic functions, so as to provide a filter material that can effectively treat particles and VOCs at the same time.

The reason is, in order to achieve the above-mentioned purpose, the present invention provides a kind of needle-shaped ceria photocatalyst preparation method, and its steps comprise:

In the step of taking materials and mixing, a CeCl ₃ ·7H ₂ O solution with a concentration of 0.08M and a NaOH solution with a concentration of 10M are provided, and the two solutions are mixed at a volume ratio of 1:1 and then uniformly stirred to form a mixed solution;

In the ultrasonic vibration step, a reaction solution is formed after the mixed solution of the material taking and mixing step is subjected to ultrasonic vibration;

In the baking step, the reaction solution in the ultrasonic vibration step is poured into a polytetrafluoroethylene reactor for baking to obtain a solid;

Washing and filtering step, repeating washing and then filtering the solid matter of the baking step to obtain a solid product;

In the drying and grinding step, the solid product of the washing and filtering step is dried, ground and sieved to obtain needle-shaped ceria photocatalyst powder.

The present invention also provides a method for preparing a filter material containing needle-shaped ceria photocatalyst, the steps comprising:

The step of taking materials and mixing, providing needle-type ceria photocatalyst powder, nylon hexa and formic acid prepared by the needle-type ceria photocatalyst manufacturing method described in claim 1; The needle-shaped ceria photocatalyst powder and 15wt% nylon hexa are dissolved in formic acid to form a mixed solution;

In the ultrasonic vibration step, the mixed solution in the material-collecting and mixing step is evenly stirred, and then ultrasonic vibration is performed to obtain a ceria-containing nylon 6 polymer precursor solution;

In the fiber material filling step, the polymer precursor solution in the ultrasonic vibration step is filled into the needle cylinder of the electrospinning equipment, and the needle cylinder is connected with the micro-propulsion pump;

The parameter setting step is to set the working parameters of the electrospinning equipment;

In the electrospinning step, the electrospinning equipment is started, and the micro-propulsion pump pushes the needle cylinder to output the needle-shaped ceria nylon hexafiber to the cylinder collector to make a filter material containing needle-shaped ceria photocatalyst.

Another object of the present invention is to provide the use of a needle-type ceria photocatalyst, the needle-type ceria photocatalyst is prepared by the preparation method of the needle-type ceria photocatalyst as described above, and the needle-type ceria photocatalyst is Used to add photodegradation of volatile organic compounds in filter media.

Another object of the present invention is to provide the use of a needle-shaped ceria photocatalyst, the needle-shaped ceria photocatalyst is prepared by the above-mentioned preparation method, and the needle-shaped ceria photocatalyst is used for adding in a filter material to filter particle.

Another object of the present invention is to provide the use of a filter material containing needle-type ceria photocatalyst, the filter material is prepared by the method for preparing a filter material containing needle-type ceria photocatalyst as described above, and the filter material is used for using the needle-type ceria photocatalyst. Type ceria photocatalyst filters particulates as well as photodegrades volatile organic compounds.

Regarding the techniques, means and other effects adopted by the present invention to achieve the above-mentioned objects, preferred feasible embodiments are given and described in detail in conjunction with the drawings as follows.

In order to facilitate the understanding of the present invention, the following description is made with reference to FIG. 1 to FIG. 22 and the embodiments.

As shown in Figure 1, the preparation method of a kind of needle-shaped ceria photocatalyst provided by the invention, its method step comprises:

Step S11 of taking materials and mixing, providing a solution of cerium trichloride (CeCl ₃ ·7H ₂ O) with a concentration of 0.08M and a solution of sodium hydroxide (NaOH) with a concentration of 10M, and mixing the two solutions and uniformly stirring for 1 hour to form a mixed solution ;

Ultrasonic vibration step S12, the mixed solution of this material taking and mixing step S1 is subjected to ultrasonic vibration for 30 minutes to form a reaction solution;

In the baking step S13, the reaction solution of the ultrasonic vibration step S2 is poured into a polytetrafluoroethylene reaction kettle, and baking is carried out for 24 hours under the condition of a temperature of 180 °C to obtain a solid;

In the washing and filtering step S14, the solid matter in the baking step S3 is repeatedly washed with ultrapure water and ethanol for several times, and then filtered with an air pump and filter paper to obtain a solid product;

Drying and grinding step S15, the solid product of the washing and filtering step S4 is moved to an oven for drying at 80° C. for 4 hours. After grinding and sieving, needle-shaped Cerium Dioxide (Needle-shaped Cerium Dioxide, referred to as N-CeO2 for short) is obtained. ) photocatalyst powder.

Preferably, the needle-shaped ceria (N-CeO ₂ ) photocatalyst has an average diameter of 26.3±10 nm and a specific surface area of 64.8±10 m ² /g.

As shown in Fig. 2 and Fig. 3, the present invention provides a method for preparing a filter material containing needle-shaped ceria photocatalyst, which is prepared by using the aforementioned needle-shaped ceria photocatalyst as one of the raw materials for preparation and then cooperating with the electrospinning equipment 10. . 3, the electrospinning device 10 includes a working platform 11 and a micro-propulsion pump 12, a needle cylinder 13, a high voltage supply 14, a needle 15 and a cylinder collector 16 arranged thereon; specifically, the The volume of the syringe 13 is 10 mL, the needle 15 is a stainless steel needle (#21, 0.52 mm), and the precursor polymer solution for preparing the fiber is injected into the syringe 13 and connected by a needle tube 131 made of Teflon To the stainless steel needle 15, the syringe is connected to the needle 15 through the needle tube 131, the high voltage supply 14 is connected to the needle 15 to receive the high voltage static electricity output by the high voltage supply 14, the roller collector 16 is provided on the needle Below 15, the needle-shaped CeO2 Nylon 6 Fiber (Needle-shaped CeO2 Nylon 6 Fiber, N-CNF for short) output from the needle 15 in the rolling collection is used.

As shown in Figure 2, the preparation method steps of the filter material containing needle-shaped ceria photocatalyst of the present invention include:

Step S21 of taking materials and mixing, providing needle-shaped ceria (N-CeO ₂ ) photocatalyst powder, nylon hexa (Nylon 6, N-6 for short) and formic acid prepared by the above-mentioned needle-shaped ceria photocatalyst preparation method; The total weight of the aforementioned materials is measured, and 0.5wt% to 4.0wt% of needle-shaped ceria photocatalyst powder and 15wt% of nylon hexa are dissolved in formic acid to form a mixed solution;

In the ultrasonic vibration step S22, the mixed solution of the material taking and mixing step S21 is uniformly stirred by magnetic force for 6 hours, and then ultrasonic vibration is performed for 30 minutes to obtain a ceria-containing nylon hexapolymer precursor solution;

The fiber material filling step S23, the polymer precursor solution of the ultrasonic vibration step S22 is filled into the 10 mL syringe 13 of the electrospinning device 10, and the syringe 13 is connected to the micro-propulsion pump 12;

Parameter setting step S24, setting the working parameters of the electrospinning device 10;

In step S25 of electrospinning, the electrospinning device 10 is started, and the micro-propulsion pump 12 pushes the needle cylinder 13 to output needle-shaped ceria nylon hexafiber (N-CNF) to the cylinder collector 16 to make the Needle-type ceria photocatalyst filter material.

Preferably, in the parameter setting step S24, the propulsion flow of the micro propulsion pump 12 is 0.18-0.22 ml per hour (0.18-0.22 mL/hr), and the distance between the roller collector 16 and the needle 15 is 13.5 To 16.5 cm, the high voltage supply 14 outputs an electric field voltage of 22.5~27.5KV to the needle 15, and the rotation speed of the roller collector 16 is 110~135rpm. Specifically, the propulsion flow rate of the micro propulsion pump 12 is 0.2 ml per hour (0.2 mL/hr), the distance between the roller collector 16 and the needle 15 is 15 cm, and the high voltage supply 14 outputs an electric field voltage of 25KV To the needle 15, the rotational speed of the drum collector 16 is 120 rpm.

Preferably, the electrospinning step S25 also includes, before starting the electrospinning equipment, wrapping a PET substrate on the surface of the drum of the drum collector 16, so that the filter material containing the needle-type ceria photocatalyst is formed. on the PET substrate.

The first use of the needle-shaped ceria photocatalyst obtained by the preparation method of the present invention is to add photodegradation of volatile organic compounds in the filter material. Specifically, the needle-shaped ceria photocatalyst is used to add photodegradation of acetone in the filter material. The second purpose of the needle-type ceria photocatalyst obtained by the preparation method of the present invention is to add it to the filter material to filter particles. Specifically, the needle-type ceria photocatalyst is used to filter particles of 10-500 nm in the filter material.

The purpose of the filter material containing the needle-shaped ceria photocatalyst obtained by the preparation method of the present invention is to use the needle-shaped ceria photocatalyst to filter particles and photodegrade volatile organic compounds. Specifically, the filter material containing needle-shaped ceria photocatalyst is used for filtering particles of 10-500 nm and photodegrading acetone.

The preparation method and application of the needle-shaped ceria photocatalyst of the present invention, and the preparation method and application of the filter material containing the photocatalyst have been described above. Below, please refer to FIG. 4A to FIG. 22 to illustrate specific embodiments of the present invention.

In the embodiment of the present invention, the nylon 6 fiber of the blank group is abbreviated as NF (Nylon 6 Fiber); the commercial ceria of the control group is abbreviated as C-CeO ₂ (Commercial Cerium Dioxide), and the commercial ceria nylon 6 is abbreviated as NF (Nylon 6 Fiber). The fiber is abbreviated as C-CNF (Commercial C-CeO ₂ Nylon 6 Fiber); the needle-shaped ceria of the experimental group is abbreviated as N-CeO ₂ (Needle-shaped Cerium Dioxide), and the needle-shaped ceria nylon 6 fiber is abbreviated as N-CeO 2 (Needle-shaped Cerium Dioxide). Abbreviated as N-CNF (Needle-shaped CeO ₂ Nylon 6 Fiber). Among them, N-CNF is further defined as X% N-CNF according to the addition amount (X%) of N-CeO ₂ during its preparation, such as 0.5% N-CNF, which means that the N-CNF is 5% N-CNF It is prepared from CeO ₂ and nylon six.

Example 1. Surface Morphology Analysis

(1) Needle-shaped ceria (N-CeO ₂ ) photocatalyst powder

As shown in FIG. 4A and FIG. 4B , in Example 1, FE-SEM (field emission scanning electron microscope, field emission scanning electron microscope) was used to observe the powder of commercial C-CeO ₂ and N-CeO ₂ prepared by alkaline hydrothermal method difference in appearance. From Figure 1A, it can be found that C-CeO ₂ is slightly agglomerated, and the single particle has an irregular shape, and the particle size is between 40 and 100 nm; Figure 1B shows that the distribution of N-CeO ₂ is relatively dispersed, and the shape and diameter are relatively Uniform, with small differences between single particles, with an average diameter of about 26.3 nm. The agglomeration phenomenon of the photocatalyst material is small and the distribution is relatively dispersed, which can effectively improve the position of the active site excited by ultraviolet light. It can be seen from Figure 1B that the needle shape of N-CeO ₂ can increase the material can be excited. The surface area is more conducive to the generation of electron and hole pairs, and the photocatalytic performance is improved.

(2) Fiber (N-CNF) containing needle-shaped ceria (N-CeO ₂ ) photocatalyst

At present, it is known that the factors affecting the morphology of fibers prepared by electrospinning include parameters such as conductivity, molecular weight, viscosity, surface tension, fiber collection distance and voltage of the polymer solution, which can easily change the diameter and shape distribution of the fibers; Therefore, as shown in FIGS. 2A to 10B , in this example, NF, 0.5% N-CNF, 1.0% N-CNF, 2.0% N-CNF, 4.0% N-CNF and 4.0% C-CNF were observed by FE-SEM. According to the fiber type and average diameter, the diameters of the front fibers were measured to be 98.7, 90.4, 85.3, 83.3, 82.7 and 82.3 nm, respectively. Among them, as shown in Fig. 5A and Fig. 5B, the surface of NF is smooth and smooth, but after adding CeO ₂ , as shown in Fig. 6A to Fig. 10B, the surface of the fiber becomes rough and some protrusions. Since the smaller fiber diameter will make the filter material have a denser network and reduce the pore size, it will be difficult for the particles to pass through, so it has a higher removal efficiency. In other words, the smaller the fiber diameter, the better the filtration efficiency; as shown in Figure 5B, As shown in Fig. 6B, Fig. 7B, Fig. 8B, Fig. 9B and Fig. 10B, with the increase of the addition amount, the average diameter of the fibers has a decreasing trend, from 98.7 nm to 82.3 nm, showing that the N-CNF prepared by the present invention Has a good filtering effect. In addition, the structure with dendrites and the increase in the number of fiber bundles also help to enhance Brownian diffusion, which can improve filtration efficiency.

Example 2, Analysis of Optical Properties

As shown in FIG. 11 , in Example 11, the UV-Visible absorption spectrometer was used to detect C-CeO ₂ , N-CeO ₂ , 0.5% N-CNF, 1.0% N-CNF, 2.0% N-CNF, 4.0% N-CNF and 4.0% C-CNF material was analyzed to measure the absorption and energy gap size of the prepared material at different incident wavelengths. Figure 11 shows the full wavelength scan of the photocatalytic materials (the wavelength range is 200-700 nm). Each material has obvious absorption peaks in the ultraviolet region of 200-450 nm, and the absorption peak in the ultraviolet region is higher. It means that the photocatalyst prepared by the present invention can only be excited by the incident light in the ultraviolet range, and electron transition occurs, thereby generating electron-hole pairs with redox effect. If a tangent is drawn at the inverse inflection point of the absorption light curve, and the tangent is extended to the intersection of the X-axis, the maximum absorption wavelength can be estimated, and then calculated according to the formula (4-1), the photocatalysis can be calculated. The energy gap of the material is shown in Table 4-1.

(4-1) 其中： E：帶隙能量 (eV)； ν：輻射頻率 (Hz)； c：光速 (3×10 ⁸m s ^-1)； h：普朗克常數 (6.626×10 ^-34J s)； λ：吸收光波長 (nm)。

(4-1) where: E: band gap energy (eV); ν: radiation frequency (Hz); c: speed of light (3×10 ⁸ ms ^-1 ); h: Planck constant (6.626×10 ^-34 J s); λ: wavelength of absorbed light (nm).

The energy gap charge structure of the photocatalyst has a great influence on the photocatalytic reaction. It can be seen from Figure 11 that the N-CeO ₂ synthesized by the alkaline hydrothermal method has the best absorption capacity, the largest boundary wavelength and the smallest energy. The energy gap is about 2.75 eV, which is better than that of C-CeO ₂ (the energy gap is about 2.95 eV), that is, the energy required for the material to be excited by photon irradiation is less, and it is easier to generate electron-hole pairs, which improves the photodegradation efficiency.

Table 1: type of material Wavelength (nm) Energy gap (eV) N-CeO ₂ 450 2.75 C-CeO ₂ 422 2.95 4.0% C-CNF 415 2.98 4.0% N-CNF 420 2.95 2.0% N-CNF 412 3.00 1.0% N-CNF 410 3.02 0.5% N-CNF 411 3.01

Example 3, chemical composition analysis

Example 3 The element valence states of N-CeO ₂ and C-CeO ₂ powders were analyzed by XPS to measure the element valence states and chemical composition characteristics of the prepared materials, as shown in Figure 12, Figure 13 and Figure 14, respectively N -CeO ₂ full spectrum, Ce3d single spectrum of N-CeO ₂ and O1s single spectrum of N-CeO ₂ .

It can be seen from Figure 12 that the C1s energy level peak appears at 285.0 eV, the O1s energy level peak appears at 531.0 eV, and the Ce3d energy level peak appears at 902.0 eV, which confirms that the prepared N-CeO ₂ has no other impurities. From Figure 13, it can be observed that Ce in N-CeO ₂ has two valence states (4 ⁺ and 3 ⁺ ) at the same time, and the energy level peaks of Ce ⁴⁺ are located at 883.6 eV and 899.1 eV, representing Ce ⁴⁺ 3d _5/2 At 916.7 eV, it represents the orbital of Ce ⁴⁺ 3d _3/2 ; the energy level peak of Ce ³⁺ appears at 889.6 eV, representing the orbit of Ce ³⁺ 3d _5/2 , while 901.4 eV and At 909.5 eV, it represents the orbital of Ce ³⁺ 3d _3/2 . In addition, from the O1s spectrum in Figure 14, it can be seen that the main peak of lattice oxygen (O _latt ) is located at 529.2 eV, the energy level peak of adsorbed oxygen (O _ads ) is located at 531.8 eV, and the energy level peak caused by the water OH on the surface of the material at 533.3 eV.

In addition, regarding the ratio of the Ce valence states of N-CeO ₂ and C-CeO ₂ , after integrating the fitted peak areas, the results are shown in Table 2. The results show that the ratio of Ce ³⁺ /Ce ⁴⁺ in N-CeO ₂ is 0.51, and the ratio of Ce ³⁺ /Ce ⁴⁺ in C-CeO ₂ is 0.33, indicating that the ratio of Ce ³⁺ in N-CeO ₂ is higher than that of C -CeO ₂ , because Ce ⁴⁺ in CeO ₂ is easily reduced to Ce ³⁺ under high temperature or reducing environment, when Ce ⁴⁺ in the crystal is reduced to Ce ³⁺ , CeO ₂ in order to maintain electricity Neutrality releases oxygen ions, resulting in positively charged oxygen vacancies, resulting in essential defects. Therefore, after CeO ₂ is excited by ultraviolet light, the higher the content of Ce ³⁺ , the more holes can be provided, and the stronger reducing ability or the generation of more free radicals to degrade pollutants.

Table 2: project Ce ³⁺ /Ce ⁴⁺ O _1att /O _ads N _- CeO2/C _- CeO2 N-CeO ₂ 0.51 2.15 - C-CeO ₂ 0.33 1.04 - Ce ³⁺ - - 2.49 _Olatt - - 1.64

Example 4, nitrogen isothermal adsorption/desorption analysis

Example 4 C-CeO ₂ and N-CeO ₂ materials were analyzed by nitrogen isothermal adsorption/desorption apparatus to measure the specific surface area and pore size characteristics of the prepared materials. The analysis results are shown in Figure 15. It can be seen from Fig. 15 that its isotherm adsorption/desorption curve belongs to Type IV (medium-porosity) curve among the six types, and its adsorption/desorption behavior has four stages. The first stage is in the state of lower relative pressure. , the nitrogen adsorption amount increases slowly, which is in line with the single-layer-multi-layer adsorption of the pore wall. The second stage is that when the relative pressure is gradually increased, the nitrogen adsorption amount increases slightly, indicating the condensation phenomenon of the capillary in the middle pores. The third stage is to increase the relative pressure again. When , the nitrogen adsorption slowed down again, indicating that there was a multi-layer adsorption phenomenon on the outside of the material, and the fourth stage was characterized by that when the relative pressure was close to saturation (P/P ₀ = 1.0), the nitrogen adsorption increased sharply, and all the pores were removed. fill up. After the nitrogen isotherm adsorption/desorption curve is calculated through the BET equation, the specific surface area and pore size of the material can be obtained, as shown in Table 3. The results show that the specific surface area of N-CeO ₂ is 64.8 m ² g ^-1 , which is higher than that of C-CeO ₂ (44.1 m ² g ^-1 ₎ . Less agglomeration, and the average diameter is lower than C-CeO ₂ , so it has a larger specific surface area, and a photocatalyst with a large specific surface area can receive more photoelectrons to generate free radicals and act as reaction sites, thereby improving photocatalysis process.

table 3: Material Specific surface area (m ² g ^-1 ) Pore volume (cm ³ g ^-1 ) Pore size (nm) N-CeO ₂ 64.8 0.056 2.9 C-CeO ₂ 44.1 0.095 8.6

Example 5, filtration test of PET substrate

In order to improve the structural strength of the fiber filter material prepared by the electrospinning technology, the present invention selects non-woven fabric (PET) as the base material to make the composite filter material. Embodiment 5 utilizes wide-range particle size analyzer (Wide-range Particle size Spectrometer, be called for short WPS) to carry out the measurement of total number of particles and particle size distribution after filtration, and the particle size range that produces particle is 10-500 nm, and the total number of particles is 10-500 nm. Stable control is between 1.80 × 10 ⁶ ~2.10 × 10 ⁶ # cm ^-3 , the surface speed is 5.0 cm s ^-1 , and the filtration test is carried out on the PET substrate. The results are shown in Figure 16. It can be known that the smaller the particle size of the particulate matter, the lower the penetration rate, and the particle removal is mainly contributed by the Brownian diffusion mechanism, and as the particle size increases, the penetration rate gradually increases. Due to the coarse fiber diameter and high porosity of the PET substrate, the direct interception mechanism is not easy to occur, causing the particles to directly penetrate the PET substrate instead of being intercepted. Among them, the Most Penetrating Particulate Size (MPPS) is 309 nm.

Embodiment 6, the filtration test of filter material containing ceria

In Example 6, the total number of particles and particle size distribution before and after filtration were measured by WPS. The particle size range of the generated particles was 10 - 500 nm, and the total number of particles was stably controlled at 1.80 × 10 ⁶ -2.10 × 10 ⁶ # cm ^-3 between 5.0 cm s ^-1 and 0.2 gm ^-2 basis weight, and using 0.5% N-CNF, 1.0% N-CNF, 2.0% N-CNF and 4.0% N-CNF materials for filtration performance The test results are shown in Figure 17. It can be seen that the transmittance decreases with the increase of CeO ₂ content, the average transmittance is 1.05%, 0.65%, 0.35% and 0.17%, and the MPPS are 92 nm, 88 nm, 75 nm and 70 nm, respectively. Compared with NF filter media, CeO ₂ -containing filter media has better filtration effect. However, adding too much N-CeO ₂ (such as 5% N-CNF) can easily lead to problems such as needle blockage and fiber breakage, and it is difficult to be sprayed into a more complete Therefore, in the embodiment of the present invention, 4% N-CNF is selected as the best material, and this material also has the best filtration efficiency. In addition, it can be observed from the FE-SEM of Fig. 5A to Fig. 10B that as the content of N-CeO ₂ increases, the fiber diameter tends to decrease, which leads to the decrease of the most easily penetrable particle size.

Embodiment 7, the photodegradation performance test of ceria content

Example 7 Photodegradation experiments were carried out using four different N _- CeO addition amounts of filter media (0.5% N-CNF, 1.0% N-CNF, 2.0% N-CNF and 4.0% N-CNF) with a residence time of 90 s , the lamp source is 254 nm, and the acetone concentration is 50 ppm, as shown in Figure 18. The degradation efficiencies were 46.4%, 56.6%, 68.9% and 80.0%, respectively. The needle-type ceria test results showed the same trend as the commercial ceria. With the increase of catalyst content, the degradation effects were further improved. .

Example 8, Photodegradation Cycle Test

Example 8 The same piece of filter material (4.0% N-CNF) was tested for 5 cycles of photodegradation, the initial concentration of acetone was 50 ppm, the residence time was 90 s, the light source was 254 nm, and the concentration in the reactor was set to reach adsorption equilibrium. test. It can be seen from the results that 4.0% N-CNF did not show the degradation of photocatalyst activity in the 5 cycle tests, and its degradation efficiency was maintained at about 80%, as shown in Figure 19, it showed a good performance in the cycle degradation test. stability.

Example 9, filtration and photocatalytic synergistic treatment performance

Example 9 was tested using 4.0% N-CNF, which has good performance in both filtration and photodegradation, and the following two cases were discussed respectively. 1. Effects on particle filtration (surface velocity of 5.0 cm s ^-1 ) at different initial concentrations of acetone (25, 50, 75 and 100 ppm); 2. Different particle number concentrations (1.2 × 10 ⁵ , 2.1 × 10 ^{5 )} , 3.3 × 10 ⁵ and 8.7 × 10 ⁵ # cm ^-3 , corresponding to filter surface velocities of 1.0, 3.0, 5.0 and 10.0 cm s ^-1 , respectively, for photodegradation of acetone (initial concentration of 50 ppm; residence time of 90 s) ) influence.

Example 9 Using WPS and PID to measure the total number of particles, particle size distribution and acetone concentration before and after treatment respectively, the fiber basis weight used was 0.2 gm ^-2 , and the total number of particles concentration was stably controlled at 1.80 × 10 ⁶ ~ 2.10 Between × 10 ⁶ # cm ^-3 , the concentration in the reactor was set to reach the adsorption equilibrium, and then the light was tested. The experimental results are shown in Figure 20 to Figure 21. It can be seen from Figure 20 and Figure 21 that no matter whether the air stream contains acetone or not, the effect on the filtering effect of particles in each particle size is not obvious. When the initial concentration of acetone is 25, 50, 75 and 100 ppm, the Efficiencies are maintained at around 98.82% (± 0.02%). Since the main mechanism of fiber filtration of particles is direct interception and Brownian diffusion, the impact on particle filtration is small when gaseous pollutants such as acetone are contained in the airflow.

The effect of the concentration of particles in the airflow on the photodegradation of acetone is more obvious. It can be seen from Figure 22 that with the increase of the surface velocity, the higher the concentration of particles remaining in the airflow, the worse the filtering effect, resulting in the photodegradation efficiency of acetone. There is an obvious downward trend. When the surface velocities are 1.0, 3.0, 5.0 and 10.0 cm s ^-1 respectively, the number concentrations of particles remaining in the airflow are about 1.2 × 10 ⁵ , 2.1 × 10 ⁵ , 3.3 × 10 ⁵ and 8.7 × 10 ⁵ # cm ^-3 , and the photodegradation efficiencies of acetone were 74.2%, 72.4%, 70.3% and 64.4% (± 2.2%), respectively; in contrast, when there were almost no particles in the airflow, the photodegradation efficiency The efficiency can reach 80.0%. It is because the particles in the airflow will gradually accumulate on the surface of the fiber, forming a dust cake and shielding the ultraviolet light, so that the N-CeO ₂ cannot be excited to form electron/hole pairs, or the particles directly attach to the photocatalyst, making the N-CeO 2 not excited. ₂ It is difficult to adsorb acetone molecules for degradation reaction and other reasons, so that the photocatalytic reaction is not easy to occur, which in turn leads to a decrease in efficiency.

S11: Material mixing step S12: Ultrasonic vibration steps S13: Baking step S14: washing and filtering step S15: Dry grinding step S21: material mixing step S22: Ultrasonic vibration steps S23: Fiber Material Filling Step S24: Parameter setting steps S25: Electrospinning step 10: Electrospinning Equipment 11: Work Platform 12: Micropropulsion pump 13: Syringe 131: Needle tube 14: High voltage supply 15: Needle 16: Roller collector

Fig. 1 is the schematic diagram of the manufacturing method steps of the needle-shaped ceria photocatalyst of the present invention; Fig. 2 is the schematic diagram of the manufacturing method steps of the filter material containing the needle-shaped ceria photocatalyst of the present invention; Fig. 3 is the structural schematic diagram of the electrospinning equipment of the present invention; Fig. 4A is the FE-SEM surface morphology analysis of the commercial ceria (C-CeO ₂ ) of Example 1; FIG. 4B is the FE-SEM surface morphology of the needle-type ceria (N-CeO ₂ ) of Example 1 Analysis; Fig. 5A, Fig. 5B are the FE-SEM surface morphology analysis (Fig. 5A) and diameter distribution (Fig. 5B) of the nylon hexafiber (NF) of Example 1; Fig. 6A, Fig. 6B are CeO ₂ in Example 1 FE-SEM surface morphology analysis (Fig. 6A) and diameter distribution (Fig. 6B) of needle-shaped ceria nylon hexafiber (N-CNF) with a content of 0.5%; Fig. 7A, Fig. 7B are the CeO ₂ content in Example 1 FE-SEM surface morphology analysis (Fig. 7A) and diameter distribution (Fig. 7B) of 1.0% needle-shaped ceria nylon _hexafiber (N-CNF); FE-SEM surface morphology analysis (Fig. 8A) and diameter distribution (Fig. 8B) of % needle-shaped ceria nylon _hexafiber (N-CNF); FE-SEM surface morphology analysis (Fig. 9A) and diameter distribution (Fig. 9B) of needle-shaped ceria nylon _hexafiber (N-CNF); FE-SEM surface morphology analysis (Fig. 10A) and diameter distribution (Fig. 10B) of commercial ceria nylon hexafiber (C-CNF); Fig. 11 is the UV-Vis analysis of different photocatalytic materials in Example 2 Figure 12 is the XPS analysis pattern of the N-CeO ₂ of Example 3; Figure 13 is the Ce3d single XPS analysis pattern of the N-CeO ₂ of Example 3; Figure 14 is the N-CeO ₂ of Example 3 The O1s alone XPS Analysis spectrum; Figure 15 is the nitrogen isotherm adsorption/desorption curve diagram of N-CeO ₂ and C-CeO ₂ in Example 4; Figure 16 is the penetration rate of the PET substrate in Example 5; Figure 17 is an example The transmittance of N-CNF with different CeO ₂ content in 6; Figure 18 is the degradation efficiency of N-CNF with different CeO ₂ content to acetone in Example 7 (retention time 90s; initial concentration 50ppm; light source 254nm); Figure 19 is the implementation Photodegradation cycle test of acetone in Example 8 (retention time 90s; initial concentration 50ppm; material 4.0% N-CNF; light source 254nm); Figure 20 is the effect of simultaneous treatment of acetone on filtration in Example 9 (surface velocity 5.0cm/s ; initial concentration 50ppm); Figure 21 is the effect of acetone concentration change on filtration in Example 9 (surface velocity 5.0cm/s; particle number concentration 2.0×10 ⁶ #cm ^-3 ); Figure 22 is the effect of particle number concentration on photocatalytic degradation of acetone in Example 9 (initial concentration 50ppm; residence time 90s).

S11: Material mixing step

S12: Ultrasonic vibration steps

S13: Baking step

S14: washing and filtering step

S15: Dry grinding step

Claims (10)

A preparation method of a needle-shaped ceria photocatalyst, the steps include: a step of taking materials and mixing, providing a CeCl ₃ ·7H ₂ O solution with a concentration of 0.08M and a NaOH solution with a concentration of 10M, and mixing the two solutions in a volume ratio of 1:1 After mixing, uniformly stir to form a mixed solution; In the ultrasonic vibration step, the mixed solution in the material collection and mixing step is subjected to ultrasonic vibration to form a reaction solution; In the baking step, the reaction solution in the ultrasonic vibration step is poured into polytetrafluoroethylene to react Baking in the kettle to obtain solids; washing and filtering step, repeating washing and then filtering the solids in the baking step to obtain solid products; drying and grinding step, drying, grinding and sieving the solid products in the washing and filtering steps Then, needle-shaped ceria photocatalyst powder was obtained. The method for producing a needle-shaped ceria photocatalyst according to claim 1, wherein the needle-shaped ceria photocatalyst has an average diameter of 26.3±10 nm and a specific surface area of 64.8±10 m ² /g. A method for preparing a filter material containing needle-shaped ceria photocatalyst, the steps comprising: The step of taking materials and mixing provides needle-shaped ceria photocatalyst powder, nylon hexa and formic acid prepared by the needle-shaped ceria photocatalyst manufacturing method described in claim 1 or 2; wt% needle-shaped ceria photocatalyst powder and 15wt% nylon hexa are dissolved in formic acid to form a mixed solution; In the ultrasonic vibration step, the mixed solution in the material-collecting and mixing step is evenly stirred, and then ultrasonic vibration is performed to obtain a ceria-containing nylon 6 polymer precursor solution; In the fiber material filling step, the polymer precursor solution in the ultrasonic vibration step is filled into the needle cylinder of the electrospinning equipment, and the needle cylinder is connected with the micro-propulsion pump; The parameter setting step is to set the working parameters of the electrospinning equipment; In the electrospinning step, the electrospinning equipment is started, and the micro-propulsion pump pushes the needle cylinder to output the needle-shaped ceria nylon hexafiber to the cylinder collector to make a filter material containing needle-shaped ceria photocatalyst. The method for producing a filter material containing needle-type ceria photocatalyst as claimed in claim 3, wherein the electrospinning equipment comprises a working platform and the micro-propulsion pump, the needle cylinder, a high-voltage supply set on the working platform a device, a needle and the roller collector; wherein, the needle is connected to the needle through a needle tube, the high-voltage supply is connected to the needle to receive high-voltage static electricity output from the high-voltage supplier, and the roller collector is arranged on the needle Below, the needle-shaped ceria nylon hexafiber output from the needle in the rolling collection; In the parameter setting step, the propulsion flow of the micro propulsion pump is 0.18-0.22 ml per hour, the distance between the roller collector and the needle is 13.5-16.5 cm, and the high-voltage power supply outputs an electric field of 22.5-27.5KV Voltage is applied to the needle, and the rotational speed of the roller collector is 110-135 rpm. The method for producing a filter material containing needle-type ceria photocatalyst as claimed in claim 3, wherein the electrospinning step further comprises, before starting the electrospinning equipment, wrapping a PET substrate on the surface of the drum collector On the surface of the drum, the filter material containing the needle-shaped ceria photocatalyst is formed on the PET substrate. Use of a needle-shaped ceria photocatalyst, the needle-shaped ceria photocatalyst is prepared by the preparation method as described in claim 1 or 2, and the needle-shaped ceria photocatalyst is used for adding in a filter material to photodegrade volatile organic compounds compound. The use according to claim 6, wherein the needle-shaped ceria photocatalyst is used for adding photodegradation acetone in the filter material. Application of a needle-shaped ceria photocatalyst, the needle-shaped ceria photocatalyst is prepared by the preparation method as described in claim 1 or 2, and the needle-shaped ceria photocatalyst is used to filter particles in a filter material. The use according to claim 8, wherein the needle-shaped ceria photocatalyst is used to filter particles of 10-500 nm in the filter material. A kind of purposes of the filter material containing needle-type ceria photocatalyst, the filter material is made by the filter material preparation method containing needle-type ceria photocatalyst as described in any one of claim 3 to 5, and the filter material is used for utilizing the needle type ceria photocatalyst. Type ceria photocatalyst filters particulates as well as photodegrades volatile organic compounds.

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