Air purification composite material for removing formaldehyde and preparation method thereof
Patent Information
- Application Number
- CN202511059215.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2025-11-07
Smart Images
Figure SMS_1 
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of air purification, in particular to an air purification composite material for removing formaldehyde and a preparation method thereof. BACKGROUND
[0002] Wood materials are widely used in building decoration, furniture manufacturing and interior design due to their environmental characteristics and natural aesthetic properties. However, such materials need to be modified by adhesives and coatings during processing, resulting in the continuous release of volatile organic pollutants (VOCs) into the indoor environment. Formaldehyde, as the main pollutant, is highly toxic and can cause significant harm to the respiratory system and endocrine function of the human body if exposed for a long time, seriously threatening the safety of the living environment.
[0003] Current formaldehyde treatment technologies include physical adsorption, plasma oxidation and photocatalytic oxidation methods. Photocatalytic oxidation is considered one of the most promising solutions because it can completely mineralize formaldehyde into harmless substances under light conditions. Although existing technologies have proposed various air purification materials (such as active manganese catalysts, carbon quantum dot composite photocatalysts, Z-type heterojunction materials, etc.), the degradation rate of existing materials for low-concentration formaldehyde in indoor environments is difficult to meet the rapid purification requirements in practical applications. The performance of the materials decays quickly during continuous operation, affecting the actual service life, and composite materials with high formaldehyde degradation efficiency and broad-spectrum antibacterial ability are still in short supply.
[0004] Therefore, the present application designs an air purification composite material for removing formaldehyde and a preparation method thereof to solve the above problems. SUMMARY
[0005] In view of the above-mentioned shortcomings of the prior art, the present application provides an air purification composite material for removing formaldehyde and a preparation method thereof.
[0006] To achieve the above-mentioned purposes, the present application is implemented by the following technical solutions: An air purification composite material for removing formaldehyde, comprising: Fe-doped BiOF and porous g-C3N4, wherein the atomic ratio of Fe to Bi is 0.5-5%, the specific surface area of the porous g-C3N4 is 50-100 m 2 / g, and the pore size distribution is 2-20 nm.
[0007] Furthermore, the composite material is loaded on a honeycomb ceramic substrate, and the loading amount is 10-30% of the total weight of the composite material (using the dip-coating method: immerse the honeycomb ceramic in a composite material slurry with a solid content of 10 wt% for 5 min, the pulling speed is 2 mm / s, pre-bake at 150°C for 30 min, and calcine at 400°C for 2 h).
[0008] A preparation method of the air purification composite material for removing formaldehyde, comprising the following steps: S1: dissolving iron salt, bismuth source and fluorine source in deionized water, hydrothermal reaction at 150-170 DEG C for 12-18h, filtering, washing after cooling, drying at 60-80 DEG C for 8-12h, obtaining Fe doped BiOF; The bismuth source is bismuth nitrate, and the fluorine source is ammonium fluoride; S2: mixing urea and citric acid, calcining at 500-600 DEG C for 2-4h, naturally cooling to room temperature, ball milling treatment for 3h (rotating speed 300 rpm, zirconium oxide milling beads), and sieving through 200 mesh screen to obtain porous g-C3N4 powder; S3: mixing Fe doped BiOF of S1 and porous g-C3N4 of S2 according to mass ratio 5:1-9:1, ultrasonicating at room temperature for 1.5-2.5h, and vacuum drying at 60-80 DEG C for 10-14h to obtain the composite material; In S1, the iron salt is at least one of ferric nitrate, ferric chloride or ferric sulfate, and the molar ratio of iron to bismuth is 0.5-5:100; In S2, the mass ratio of urea to citric acid is 1:0.1-0.3.
[0009] Compared with the prior art, the present application has at least the following advantages: 1、Fe doped BiOF and porous g-C3N4 in the present application overturn the charge transfer logic of traditional I-type or Z-type heterojunction, and the high-energy band holes of Fe doped BiOF and the low-energy conduction band electrons of g-C3N4 are selectively recombined through the interface self-built electric field driving, while the strong oxidation valence band (directly oxidizing formaldehyde) of Fe doped BiOF and the strong reduction conduction band (continuously generating active oxygen) of g-C3N4 are reserved, this mechanism of reserving strong oxidation and reduction sites and inhibiting invalid recombination not only avoids the problem of oxidation capacity attenuation caused by charge transfer in I-type heterojunction, but also overcomes the complexity of interface potential barrier regulation by auxiliary catalyst in Z-type heterojunction, so that the composite material has the dual ability of rapid bond breaking (oxidation) and deep mineralization (active oxygen continuous attack) when degrading formaldehyde, and realizes the complete conversion of formaldehyde to CO2 and H2O, rather than the accumulation of intermediate products.
[0010] 2、The room temperature ultrasonic process promotes the formation of strong hydrogen bonds and electrostatic coupling between Fe-doped BiOF and the hydroxyl and amino groups on the surface of porous g-C3N4 through high-frequency cavitation effect, thereby constructing a molecular-level close-contact heterojunction interface. This interface binding mode not only reduces the charge transfer resistance across the interface (improves the charge separation efficiency), but also inhibits the peeling and agglomeration of the material during the recycling process through chemical bonding. At the same time, the lattice matching degree at the interface is improved, which can reduce the impact of photo-generated carriers on the lattice (avoiding the structural collapse caused by photo-etching), so that the material still maintains stable catalytic activity under long-term light irradiation and airflow scouring, solving the engineering problem of traditional composite photocatalysts with short-term high efficiency and long-term decay. DETAILED DESCRIPTION
[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in a clear and complete manner in combination with the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.
[0012] Embodiment 1: An air purification composite material for removing formaldehyde, comprising: consisting of Fe-doped BiOF and porous g-C3N4, wherein the atomic ratio of Fe to Bi is 0.5%, the specific surface area of the porous g-C3N4 is 50 m 2 / g, and the pore size distribution is 2 nm.
[0013] Further, the composite material is loaded on a honeycomb ceramic substrate, and the loading amount is 10% of the total weight of the composite material.
[0014] A preparation method of the air purification composite material for removing formaldehyde, comprising the following steps: S1: dissolving iron salt, bismuth source, and fluorine source in deionized water, hydrothermal reaction at 150 DEG C for 12 hours, filtering, washing, and drying at 60 DEG C for 8 hours after cooling to obtain Fe-doped BiOF; The bismuth source is bismuth nitrate, and the fluorine source is ammonium fluoride; S2: mixing urea and citric acid, calcining at 500 DEG C for 2 hours, ball milling treatment for 3 hours (rotational speed 300 rpm, zirconium oxide ball milling beads), and sieving through a 200 mesh screen to obtain porous g-C3N4 powder; S3: mixing the Fe-doped BiOF of S1 and the porous g-C3N4 of S2 according to a mass ratio of 5:1, ultrasonic treatment at room temperature for 1.5 hours (ultrasonic treatment in anhydrous ethanol medium, solid-liquid mass volume ratio is 1 g:100 mL), and vacuum drying at 60 DEG C for 10 hours to obtain the composite material. wherein the iron salt in S1 is ferric nitrate, and the molar ratio of iron to bismuth is 0.5:100; The mass ratio of urea to citric acid in S2 is 1:0.1.
[0015] Embodiment 2: An air purification composite material for removing formaldehyde, comprising: Fe-doped BiOF and porous g-C3N4, wherein the atomic ratio of Fe to Bi is 5%, and the specific surface area of the porous g-C3N4 is 100 m 2 / g, and the pore size distribution is 20 nm.
[0016] Further, the composite material is loaded on a honeycomb ceramic substrate, and the loading amount is 30% of the total weight of the composite material.
[0017] A preparation method of the air purification composite material for removing formaldehyde, comprising the following steps: S1: Dissolve an iron salt, a bismuth source, and a fluorine source in deionized water, and perform hydrothermal reaction at 170°C for 18h. After cooling, filter, wash, and dry at 80°C for 12h to obtain Fe-doped BiOF; S2: Mix urea and citric acid, calcine at 600°C for 4h, perform ball milling treatment for 3h (rotation speed 300 rpm, zirconium oxide milling beads), and pass through a 200 mesh sieve to obtain porous g-C3N4 powder; S3: Mix Fe-doped BiOF of S1 and porous g-C3N4 of S2 according to a mass ratio of 9:1, ultrasonic at room temperature for 2.5h, and vacuum dry at 80°C for 14h to obtain the composite material; wherein the iron salt in S1 is ferric chloride, and the molar ratio of iron to bismuth is 5:100; The mass ratio of urea to citric acid in S2 is 1:0.3.
[0018] Embodiment 3: An air purification composite material for removing formaldehyde, comprising: Fe-doped BiOF and porous g-C3N4, wherein the atomic ratio of Fe to Bi is 3%, and the specific surface area of the porous g-C3N4 is 78 m 2 / g, and the pore size distribution is 12 nm.
[0019] Further, the composite material is loaded on a honeycomb ceramic substrate, and the loading amount is 25% of the total weight of the composite material.
[0020] A preparation method of the air purification composite material for removing formaldehyde, comprising the following steps: S1: Dissolve an iron salt, a bismuth source, and a fluorine source in deionized water, and perform hydrothermal reaction at 165°C for 14h. After cooling, filter, wash, and dry at 70°C for 9h to obtain Fe-doped BiOF; S2: urea and citric acid were mixed, calcined at 580℃ for 3h, ball-milled for 3h (rotation speed 300rpm, zirconium oxide ball milling beads), and then sieved through a 200 mesh screen to obtain porous g-C3N4 powder; S3: Fe-doped BiOF of S1 and porous g-C3N4 of S2 were mixed at a mass ratio of 5:1, ultrasonicated at room temperature for 1.5h at 300W, and then vacuum dried at 60-80℃ for 13h to obtain the composite material; In S1, the iron salt is ferric sulfate, and the molar ratio of iron to bismuth is 3:100. In S2, the mass ratio of urea to citric acid is 1:0.2.
[0021] Comparative Example 1: The difference between this comparative example and Example 3 is that BiOF was not doped, the Fe-doping step was omitted, and pure BiOF was directly compounded with porous g-C3N4. In addition, BiOF was prepared by hydrothermal reaction of a bismuth source and a fluorine source without adding ferric sulfate.
[0022] Comparative Example 2: The difference between this comparative example and Example 3 is that Fe-doped BiOF and porous g-C3N4 were mixed by mechanical grinding (not ultrasonication at room temperature), and the ultrasonic power and time were not controlled.
[0023] Experimental Example 1: Low-concentration formaldehyde degradation performance test 0.5g of the powder was weighed and uniformly coated on a glass sheet (10cm x 10cm) (a small amount of deionized water was added to form a paste to prevent falling off), and then dried at 60℃ for 2h for standby; Experimental device and reagents: the reaction chamber was a stainless steel airtight chamber (volume 10L) with a quartz glass window (transmittance >90%, λ≥420nm), a gas sampling port, a sampling port, and a stirring fan (wind speed 0.5m / s to ensure uniform gas in the chamber). The light source was a 300W xenon lamp (with a 420nm cutoff filter, simulating visible light, light intensity 100mW / cm 2 , 20cm from the reaction chamber). The reagents were formaldehyde standard solution (1000mg / L), phenol reagent (3-methyl-2-benzothiazolone hydrazone, analytical pure), ferric ammonium sulfate (analytical pure), and concentrated hydrochloric acid (analytical pure). First, the reaction chamber was purged with high-purity nitrogen (99.999%) for 30min to remove residual organic matter, the gas inlet was closed, and 10μL of formaldehyde standard solution (1000mg / L) was injected into the chamber through the sampling port (after volatilization, the initial concentration was 10μL x 1000mg / L ÷ 10L = 1mg / m 3 , which needs to be diluted to 0.5mg / m 3: can be injected first 5 μL, and then supplement 5L high purity nitrogen, stirring 10 min mixed evenly), the pretreated material into the cabin, close the light source, start stirring fan, dark adsorption 30 min (to ensure that the material on the physical adsorption of formaldehyde to reach equilibrium), at this time record the initial concentration C0 (dark adsorption concentration, about 0.5 mg / m 3 ), turn on the light source, respectively in 30 min, 60 min from the sampling port to extract 100 mL gas, with phenol reagent spectrophotometric method to detect formaldehyde concentration.
[0024] Experimental example 2: formaldehyde concentration detection (phenol reagent method); 100 mL gas into the 5 mL phenol reagent solution (0.0015 g / mL) containing absorption tube, to the absorption liquid added 0.4 mL ferric ammonium sulfate solution (0.1 g / mL, with 0.1 mol / L hydrochloric acid preparation), shake, room temperature, avoid light for 15 min (generate blue green compounds), with UV- visible spectrophotometer (such as Shimadzu UV-2600) at 630 nm, the absorbance, into the formaldehyde standard curve (0-1.0 mg / m 3 good linearity in the range, R 2 > 0.999) to calculate the concentration; Data calculation is:
[0025] is the moment of formaldehyde concentration;
[0026] Experimental example 3: long term stability test; the same as low concentration of formaldehyde degradation performance test (reaction chamber, light source, detection method is consistent); the first degradation: according to the low concentration of formaldehyde degradation steps operation, record 60 min degradation rate (R1), after the reaction, the material is taken out, placed in vacuum drying box (-0.1 MPa, 60 DEG C) desorption 2 h (remove the surface adsorption of intermediate products), a total of 5 times the cycle (after each regeneration repeat degradation step), record the fifth degradation rate (R5), stability retention rate (%) = (R5 / R1) x 100%.
[0027] The experimental results are as follows:
[0028] From the above table, the introduction of Fe element is not a simple element substitution, but through the doping effect to realize the fine control of BiOF crystal structure, Fe 3+ ion radius and Bi 3+There are differences, and lattice distortion is formed in the BiOF lattice, which breaks the original charge balance and causes oxygen atoms to escape the lattice to form oxygen vacancies. Oxygen vacancies act as electron trapping centers, effectively adsorbing and activating oxygen molecules in the air, converting them into superoxide radicals and hydroxyl radicals with strong oxidizing properties. These active oxygen species are the core oxidation units for degrading formaldehyde. Compared with the system without Fe doping (such as Comparative Example 1), pure BiOF has high lattice integrity, and the concentration of oxygen vacancies is significantly reduced, resulting in insufficient active oxygen generation ability to efficiently break the C-H and C=O bonds in the formaldehyde molecule. This directly reflects a significant decrease in the degradation efficiency of low-concentration formaldehyde. At the same time, Fe doping can also adjust the band structure of BiOF, narrow the band gap, and enhance its absorption capacity for visible light, overcoming the limitation of traditional Bi-based materials that only respond to ultraviolet light, making it more suitable for indoor low-light environments.
[0029] Fe-doped BiOF and porous g-C3N4 achieve the preservation of strong oxidation sites and strong reduction sites. The conduction band electrons of Fe-doped BiOF and the valence band holes of porous g-C3N4 recombine at the interface, while the remaining valence band holes of Fe-doped BiOF (strong oxidizing property) can directly oxidize adsorbed formaldehyde molecules, and the conduction band electrons of porous g-C3N4 (strong reducing property) are used to activate oxygen to generate active oxygen species. This charge separation mechanism not only avoids the ineffective recombination of carriers (reduces the recombination probability), but also maximizes the intrinsic oxidation-reduction ability of the two materials, significantly improving the overall efficiency of the photocatalytic reaction.
[0030] The room temperature ultrasonic process adopted, compared with the mechanical grinding mixing of Comparative Example 2, the ultrasonic self-assembly promotes the formation of hydrogen bonds or electrostatic interactions between the functional groups such as hydroxyl and amino groups on the surface of Fe-doped BiOF and porous g-C3N4 through the shear force and cavitation effect generated by high-frequency mechanical vibration, achieving close and uniform contact between the two materials, and building a stable interface bond. This interface structure not only reduces the transfer resistance of charges between the heterojunction (reduces energy loss in the charge transfer process), but also resists photo-erosion and mechanical wear in long-term use, avoiding material shedding or interface separation. This directly explains the phenomenon that the performance retention rate of the embodiment is significantly higher than that of Comparative Example 2 in the long-term stability test.
[0031] The mass ratio of Fe-doped BiOF to porous g-C3N4, the specific surface area and pore size distribution of porous g-C3N4, and other parameters are not randomly set, but are based on the optimization results of the adsorption and catalysis synergy mechanism. The high specific surface area and mesoporous structure of porous g-C3N4 can quickly capture low-concentration formaldehyde through physical adsorption, but its own catalytic activity is limited. Fe-doped BiOF is the core unit of catalytic degradation, but the adsorption capacity is weak, and the proportion of the two needs to realize the dynamic matching of the adsorption amount and the catalytic amount. If the proportion of porous g-C3N4 is too high (such as deviating from 5:1 or 9:1 of the embodiment), the catalytic active sites will be diluted, and if the proportion is too low, the formaldehyde cannot be effectively enriched. The performance advantage of the embodiment 3 is due to this balance. The specific surface area and pore size of porous g-C3N4 can efficiently adsorb formaldehyde and provide sufficient loading interface for Fe-doped BiOF, ensuring that the adsorbed formaldehyde is quickly degraded into CO2 and H2O to form a continuous cycle of adsorption, degradation and re-adsorption, and finally realizing efficient and rapid purification of low-concentration formaldehyde.
[0032] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. An air purification composite material for removing formaldehyde, characterized by, The composite material is loaded on a honeycomb ceramic substrate, and the loading amount is 10-30% of the total weight of the composite material. Fe-doped BiOF and porous g-C3N4, wherein the atomic ratio of Fe to Bi is 0.5-5%, the specific surface area of the porous g-C3N4 is 50-100 m 2 / g, and the pore size distribution is 2-20 nm.
2. The air purification composite material for removing formaldehyde according to claim 1, characterized in that, The method comprises the following steps:
3. A method for preparing the air purification composite material for removing formaldehyde according to any one of claims 1-2, characterized in that, S1: Dissolve an iron salt, a bismuth source and a fluorine source in deionized water, and perform hydrothermal reaction at 150-170 ℃ for 12-18 h. After cooling, filtration, washing and drying, Fe-doped BiOF is obtained; S2: Mix and calcine urea and citric acid at a mass ratio of 1:0.1-0.3, ball mill and sieve to obtain porous g-C3N4 powder; S3: Mix Fe-doped BiOF of S1 and porous g-C3N4 of S2 at a mass ratio of 5:1-9:1, perform ultrasonic treatment at room temperature for 1.5-2.5 h, and dry to obtain a composite material. In S1, the iron salt is at least one of ferric nitrate, ferric chloride or ferric sulfate, and the molar ratio of iron to bismuth is 0.5-5:
100.
4. The method for preparing the air purification composite material for removing formaldehyde according to claim 3, characterized in that, In S1, the drying temperature is 60-80 ℃, and the drying time is 8-12 h.
5. The method for preparing the air purification composite material for removing formaldehyde according to claim 3, characterized in that, In S2, the calcination temperature is 500-600 ℃, and the calcination time is 2-4 h.
6. The method for preparing the air purification composite material for removing formaldehyde according to claim 3, characterized in that, In S3, the power of ultrasonic self-assembly is 200-400 W.
7. The method for preparing an air purification composite material for removing formaldehyde according to claim 3, characterized in that, In S3, the drying method is vacuum drying, the temperature is 60-80 ℃, and the time is 10-14 h.
8. The method for preparing an air purification composite material for removing formaldehyde according to claim 3, characterized in that,