Air purification material with adsorption and photocatalysis synergy and preparation method and application thereof

Abstract

The application provides an adsorption and photocatalysis synergic air purification material and a preparation method and application thereof, and belongs to the technical field of air purification. The adsorption and photocatalysis synergic air purification material comprises a manganese oxide compound, graphite phase carbon nitride, activated carbon and a periodic acid layer; wherein the manganese oxide compound and the graphite phase carbon nitride form a heterojunction, and are attached to the inner and outer surfaces of the activated carbon; and the periodic acid layer wraps the manganese oxide compound and the graphite phase carbon nitride forming the heterojunction and the activated carbon.

Description

Technical Field

[0001] This invention belongs to the field of air purification technology, specifically relating to an air purification material that combines adsorption and photocatalysis, its preparation method, and its application. Background Technology

[0002] Dining venues are common sources of indoor odors. During cooking, a large amount of volatile organic compounds (VOCs) and oil droplets are generated and emitted into the environment. VOCs in cooking fumes have been found to contain various hydrocarbons, such as alkanes, alkenes, aldehydes, ketones, and aromatic hydrocarbons. Among them, acetaldehyde and limonene, as ozone precursors, can produce ozone through photochemical reactions. Limonene and other alkenes, under certain concentrations of ozone and photolysis, can further generate secondary organic aerosols, harming the natural environment and human health. In terms of odor perception, aldehydes and ketones are key odor-producing compounds in dining venues, being the main volatiles in various foods and cooking fumes, and their concentrations are relatively high. The odor threshold of aldehydes and ketones is relatively low (i.e., their characteristic pungent odor can be perceived by people at relatively low concentrations), approximately 2.59-9.01 μg / m³. 3 To improve air quality in dining establishments and reduce the harm of gaseous organic compounds to human health, removing gaseous aldehydes and ketones is particularly important.

[0003] Purification technologies suitable for catering establishments include adsorption, catalytic oxidation, photocatalysis, and ozone oxidation. In recent years, many adsorption materials have been developed to remove gaseous aldehydes and ketones from indoor air. However, most adsorption materials have limited adsorption capacity, and desorption occurs after adsorption saturation, generating secondary pollution during the desorption process. Photocatalysis technology is considered the preferred technology for purifying low-concentration gases due to its suitability for low-flow-rate gases and its ability to operate under mild conditions. However, this technology also has its own limitations, such as lower purification efficiency; the production of ozone as a byproduct of ultraviolet light degradation; and the inability to selectively purify single pollutants. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an air purification material that combines adsorption and photocatalysis, its preparation method, and its application, aiming to at least partially solve the above-mentioned technical problems. The specific technical solution provided by this invention is as follows.

[0005] As a first aspect of the present invention, an adsorption and photocatalytic synergistic air purification material is provided, comprising: manganese oxide, graphitic carbon nitride, activated carbon, and a periodic acid layer; wherein the manganese oxide and graphitic carbon nitride form a heterojunction and are attached to the inner and outer surfaces of the activated carbon, and the periodic acid layer encapsulates the manganese oxide, graphitic carbon nitride, and activated carbon that form the heterojunction.

[0006] As a second aspect of the present invention, a method for preparing an air purification material with synergistic adsorption and photocatalysis is provided, comprising: mixing and calcining manganese oxide, graphitic carbon nitride and activated carbon to obtain an air purification precursor material; impregnating the air purification precursor material in a periodic acid solution and drying it to obtain an air purification material; wherein, during the calcination process, the manganese oxide and graphitic carbon nitride form a heterojunction and adhere to the inner and outer surfaces of the activated carbon, and during the impregnation process, the periodic acid layer encapsulates the heterojunction-forming manganese oxide, graphitic carbon nitride and activated carbon.

[0007] As a third aspect of the present invention, an application of an adsorption and photocatalytic synergistic air purification material in air purification is provided.

[0008] Based on the above technical solution, the air purification material with adsorption and photocatalysis synergistic effect provided by the present invention, its preparation method and application, has at least one of the following beneficial effects:

[0009] (1) In this embodiment of the invention, the air purification material is composed of manganese oxide, graphitic carbon nitride, activated carbon, and a periodic acid layer. The manganese oxide and graphitic carbon nitride form a heterojunction, with some manganese oxide and graphitic carbon nitride loaded on the outer surface of the activated carbon, and some manganese oxide and graphitic carbon nitride entering the pores of the activated carbon and anchoring on the inner surface of the activated carbon; the periodic acid layer encapsulates the manganese oxide, graphitic carbon nitride, and activated carbon. The periodic acid layer selectively adsorbs and fixes hydrophilic volatile organic compounds in the air. Under light irradiation, the heterojunction formed by the manganese oxide and graphitic carbon nitride generates superoxide radicals, oxidizing and decomposing the adsorbed and fixed hydrophilic volatile organic compounds into carbon dioxide and water. The activated carbon provides more adsorption sites for the manganese oxide and graphitic carbon nitride, thereby enhancing the contact between the manganese oxide and graphitic carbon nitride and the hydrophilic volatile organic compounds, and enhancing the oxidative decomposition of the hydrophilic volatile organic compounds. This invention combines adsorption and photocatalysis, solving the problems of adsorption saturation in activated carbon adsorption materials and the limited adsorption sites of manganese oxides and graphitic carbon nitride photocatalysts. This extends the service life of activated carbon adsorption materials and improves the catalytic efficiency of manganese oxides and graphitic carbon nitride photocatalysts, thereby enhancing the purification efficiency of air purification materials.

[0010] (2) In this embodiment of the invention, manganese oxide, graphitic carbon nitride, and activated carbon are mixed and calcined. During calcination, the manganese oxide and graphitic carbon nitride form heterojunctions. Some of the manganese oxide and graphitic carbon nitride are loaded on the outer surface of the activated carbon, while some enter the pores of the activated carbon and anchor on the inner surface, thus obtaining an air purification precursor material. The air purification precursor material is then impregnated in a periodic acid solution. During impregnation, a periodic acid layer is formed on the surface of the heterojunctions formed by the manganese oxide and graphitic carbon nitride, as well as the activated carbon. After drying, the air purification material is obtained. The method for preparing the air purification material in this invention is simple, easy to operate, and has the potential for large-scale production.

[0011] (3) In this embodiment of the invention, an in-situ water layer (self-wetting layer) is formed on the surface of the air purification material by adsorbing water vapor in the air through a periodic acid layer, forming a unique three-phase system of air / water / air purification material. The in-situ water layer adsorbs hydrophilic volatile organic compounds, and activated carbon adsorbs the hydrophilic volatile organic compounds in the in-situ water layer, providing more reaction sites for the oxidative decomposition of hydrophilic volatile organic compounds by manganese oxides and graphite phase carbon nitride. Under light, the heterojunction formed by manganese oxides and graphite phase carbon nitride generates superoxide radicals, which oxidize and decompose the hydrophilic volatile organic compounds adsorbed by activated carbon into carbon dioxide and water. By utilizing the synergistic effect of adsorption and photocatalysis, the purification efficiency of the air purification material can be effectively improved, achieving the goal of more economical, efficient, and selective air purification. Attached Figure Description

[0012] Figure 1 This is a scanning electron microscope image of the activated carbon in Example 1 of the present invention;

[0013] Figure 2 This is a scanning electron microscope image of graphitic carbon nitride in Comparative Example 1 of the present invention.

[0014] Figure 3 This is a scanning electron microscope image of the air purification material in Embodiment 1 of the present invention;

[0015] Figure 4 The nitrogen adsorption-desorption curves are for activated carbon in Example 1 of the present invention, air purification precursor materials in Examples 1, 3, and 5, and graphitic carbon nitride in Comparative Example 1.

[0016] Figure 5 This is a schematic diagram of a continuous flow pipeline system for testing acetaldehyde purification capacity in an embodiment of the present invention;

[0017] Figure 6 for Figure 5 Schematic diagram of the glass fiber filter membrane groove required for loading test materials in the catalytic reaction chamber of a continuous flow pipeline system;

[0018] Figure 7 The graph shows the acetaldehyde removal performance test results of Comparative Examples 1-4 and Example 10 of this invention;

[0019] Figure 8 The graph shows the test results of acetaldehyde adsorption performance in continuous flow dark environment for Examples 1-5 and Comparative Example 1 of the present invention;

[0020] Figure 9 The graph shows the acetaldehyde removal performance test results of Examples 1-10 and Comparative Example 4 of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0022] In realizing the concept of this invention, it was discovered that existing air purification methods using adsorbent materials suffer from problems such as short lifespan and lack of selectivity due to adsorption saturation. Using photocatalytic materials alone for air purification results in a limited number of adsorption sites and low purification efficiency. Therefore, this invention provides a synergistic air purification material combining adsorption and photocatalysis, its preparation method, and its applications. The synergistic air purification material in this invention comprises manganese oxides, graphitic carbon nitride, activated carbon, and periodic acid.

[0023] Activated carbon, when used as an adsorbent for air purification, suffers from adsorption saturation, resulting in a short lifespan. Once saturated, it desorbs, causing secondary pollution. Furthermore, activated carbon lacks selectivity and cannot effectively remove single pollutants. Graphitic carbon nitride is an excellent photocatalytic material, but it suffers from low quantum efficiency, low visible light photoelectric conversion rate, limited active sites, and is difficult to recycle.

[0024] Significant differences exist in air purification research experiments, making a systematic comparison of the merits of various substrates impossible. Therefore, when selecting substrates, relatively mature formaldehyde purification studies are primarily referenced. Different metal oxides exhibit varying reactivity with aldehydes. Among them, silver oxide, palladium oxide, cobalt oxide, manganese dioxide, titanium dioxide, cerium oxide, and manganese tetroxide achieve formaldehyde removal rates exceeding 50%, while lanthanum oxide, zinc oxide, and vanadium pentoxide show almost no effect on formaldehyde removal. Of these materials, manganese dioxide exhibits high reactivity in formaldehyde purification, and its various crystal structures, such as α, β, γ, λ, δ, and ε-MnO2, significantly influence its oxidative decomposition activity of formaldehyde. However, using manganese oxides alone as photocatalysts suffers from low catalytic efficiency and a limited light absorption range. Manganese has a 3d electron structure. 5 4s 2Manganese oxides, possessing multiple valence states from -3 to +7, can modulate electrons to create the mobile electron environment required for redox reactions when manganese dioxide and manganese tetroxide are calcined together. Therefore, when manganese oxides are doped with other photocatalysts, a synergistic effect is produced, which can significantly increase oxygen vacancies with strong redox properties.

[0025] However, when manganese oxides and graphitic carbon nitride are mixed and calcined to form a heterojunction, and then used as a photocatalyst for air purification, there is a problem of insufficient adsorption sites, and the volatilization of intermediate products during the purification process can cause secondary pollution. Furthermore, when air purification materials composed of activated carbon, manganese oxides, and graphitic carbon nitride are used for air purification, inorganic salts and large-molecule volatile organic compounds in the air will occupy the adsorption sites of activated carbon, thereby consuming the superoxide radicals generated by manganese oxides and graphitic carbon nitride, reducing air purification efficiency.

[0026] Therefore, this invention provides an air purification material that combines adsorption and photocatalysis, comprising manganese oxides, graphitic carbon nitride, activated carbon, and periodic acid. A layer of periodic acid is coated around the activated carbon, manganese oxides, and graphitic carbon nitride. Periodic acid selectively adsorbs and fixes hydrophilic volatile organic compounds (such as aldehydes and ketones) in the air, and the adsorbed and fixed hydrophilic volatile organic compounds are transported to the activated carbon. The activated carbon acts as a carrier, supporting the heterojunction of manganese oxides and graphitic carbon nitride; it also provides reaction sites for the heterojunction of manganese oxides and graphitic carbon nitride, thereby enhancing the oxidative decomposition of hydrophilic volatile organic compounds. The oxidative decomposition of hydrophilic volatile organic compounds by the heterojunction of manganese oxides and graphitic carbon nitride is achieved through a photocatalytic reaction that produces reactive oxygen species. The mechanism of the photocatalytic reaction is as follows: when light with energy greater than or equal to the catalyst band gap irradiates the catalyst surface, electrons in the catalyst's valence band are excited and jump to its conduction band, leaving relatively stable holes in the valence band, thus forming electron-hole pairs. Holes in the valence band of the catalyst can react with water or hydroxyl groups adsorbed on the surface to produce hydroxyl radicals (•OH). Electrons in the conduction band can combine with oxygen to produce superoxide radicals (•O2). - The conduction band (CB) edge ratio is O2 / •O2. -Semiconductors with more negative potentials can transfer photogenerated electrons to the π* orbitals of oxygen molecules, thus readily generating superoxide radicals. Superoxide radicals tend to react with compounds containing carbon-oxygen double bonds (such as aldehydes and ketones), while hydroxyl radicals tend to react with compounds containing unsaturated bonds (such as benzenes). Graphite-phase carbon nitride, due to its relatively negative conduction band, readily generates superoxide radicals under light, and under the mobile electron environment provided by manganese oxides, graphite-phase carbon nitride generates superoxide radicals even more readily under light. Therefore, based on the selective adsorption of hydrophilic volatile organic compounds by periodic acid, and under the condition that manganese oxides and graphite-phase carbon nitride are more likely to generate superoxide radicals, the air purification material provided by this invention can selectively oxidize and decompose hydrophilic volatile organic compounds containing carbon-oxygen double bonds. This invention, by combining the adsorption of periodic acid and activated carbon with the oxidative decomposition of a photocatalyst, effectively improves air purification efficiency while extending the service life of air purification materials and solving the problems of adsorption saturation and insufficient reactive sites.

[0027] As a first aspect of the present invention, an adsorption and photocatalytic synergistic air purification material is provided, comprising: manganese oxide, graphitic carbon nitride, activated carbon, and a periodic acid layer; wherein the manganese oxide and graphitic carbon nitride form a heterojunction and are attached to the inner and outer surfaces of the activated carbon, and the periodic acid layer encapsulates the manganese oxide, graphitic carbon nitride, and activated carbon that form the heterojunction.

[0028] In this embodiment of the invention, the air purification material is composed of manganese oxides, graphitic carbon nitride, activated carbon, and a periodic acid layer. The manganese oxides and graphitic carbon nitride form a heterojunction, with some manganese oxides and graphitic carbon nitride loaded on the outer surface of the activated carbon, and some entering the pores of the activated carbon and anchoring on its inner surface. The periodic acid layer encapsulates the manganese oxides, graphitic carbon nitride, and activated carbon. The periodic acid layer selectively adsorbs and fixes hydrophilic volatile organic compounds (VOCs) in the air. Under light irradiation, the heterojunction formed by the manganese oxides and graphitic carbon nitride generates superoxide radicals, oxidizing and decomposing the adsorbed and fixed hydrophilic VOCs into carbon dioxide and water. The activated carbon provides more adsorption sites for the manganese oxides and graphitic carbon nitride, enhancing the contact between them and the hydrophilic VOCs, and thus enhancing the oxidative decomposition of the hydrophilic VOCs. This invention combines adsorption and photocatalysis, solving the problems of adsorption saturation in activated carbon adsorption materials and the limited adsorption sites of manganese oxides and graphitic carbon nitride photocatalysts. This extends the service life of activated carbon adsorption materials and improves the catalytic efficiency of manganese oxides and graphitic carbon nitride photocatalysts, thereby enhancing the purification efficiency of air purification materials.

[0029] As a second aspect of the present invention, a method for preparing an air purification material with synergistic adsorption and photocatalysis is provided, comprising: mixing and calcining manganese oxide, graphitic carbon nitride and activated carbon to obtain an air purification precursor material; impregnating the air purification precursor material in a periodic acid solution and drying it to obtain an air purification material; wherein, during the calcination process, the manganese oxide and graphitic carbon nitride form a heterojunction and adhere to the inner and outer surfaces of the activated carbon, and during the impregnation process, the periodic acid layer encapsulates the heterojunction-forming manganese oxide, graphitic carbon nitride and activated carbon.

[0030] In this embodiment of the invention, manganese oxide, graphitic carbon nitride, and activated carbon are mixed and calcined. During calcination, the manganese oxide and graphitic carbon nitride form heterojunctions. Some of the manganese oxide and graphitic carbon nitride are loaded on the outer surface of the activated carbon, while some enter the pores of the activated carbon and anchor on its inner surface, thus obtaining an air purification precursor material. The air purification precursor material is then impregnated in a periodic acid solution. During impregnation, a periodic acid layer forms on the surface of the heterojunctioned manganese oxide and graphitic carbon nitride, as well as the activated carbon. After drying, the air purification material is obtained. The method for preparing the air purification material in this invention is simple, easy to operate, and has the potential for large-scale production.

[0031] According to embodiments of the present invention, the periodic acid loading in the air purification material is 30-50%. The hydroxyl groups on the surface of periodic acid give it high hygroscopicity. Hydrogen bonds form between water molecules and hydroxyl groups, creating an in-situ water layer on the surface of the air purification material, thus forming a unique air / water / air purification material three-phase system. This in-situ water layer more easily adsorbs hydrophilic volatile organic compounds while reducing the adsorption of non-hydrophilic volatile organic compounds, allowing the air purification material to selectively purify pollutants in the air.

[0032] According to embodiments of the present invention, the size of the manganese oxide compound is 10-300 nm, the size of the graphitic carbon nitride is 10-300 nm, and the size of the activated carbon is 150-425 μm. The sizes of the manganese oxide compound, graphitic carbon nitride, and activated carbon affect the specific surface area of ​​the air purification material, which in turn affects the reaction sites and adsorption sites during the purification reaction, ultimately affecting the purification efficiency of the air purification material.

[0033] According to an embodiment of the present invention, a precursor material for air purification is obtained by mixing and calcining manganese oxide, graphitic carbon nitride, and activated carbon, comprising: mixing manganese oxide, graphitic carbon nitride, and activated carbon and calcining at 320-370°C for 2.5-4 hours. Specifically, the preparation method comprises: mixing manganese oxide, graphitic carbon nitride, and activated carbon and adding them to deionized water, and magnetically stirring at 30°C for 30-60 minutes to form a homogeneous mixed solution; then maintaining the mixed solution at 120-200°C for 8-16 hours; after the reaction, washing with water and anhydrous ethanol by centrifugation 3-5 times respectively, and drying at 60-100°C for 12-14 hours after washing; after drying, heating from room temperature to 320-370°C at a heating rate of 9-11°C / min, and calcining at 320-370°C for 6-9 hours. During the mixing process, some manganese oxides and graphitic carbon nitrides are loaded on the outer surface of the activated carbon, while others enter the pores of the activated carbon and anchor on its inner surface. During calcination, the manganese oxides and graphitic carbon nitrides form heterojunctions. Excessively high or low calcination temperatures, or excessively long or short calcination times, will disrupt the heterojunctions formed between the manganese oxides and graphitic carbon nitrides.

[0034] According to embodiments of the present invention, graphitic carbon nitride is obtained by calcining urea or melamine, wherein the calcination temperature for forming graphitic carbon nitride is 500-550°C, and the calcination time is 1.5-2.5 h. Specifically, the preparation method includes: placing urea or melamine in a ceramic crucible (the amount of urea or melamine does not exceed half the volume of the crucible), covering the crucible with a lid, wrapping the outside of the crucible with aluminum foil, and placing it in a muffle furnace for calcination; raising the temperature from room temperature to 500-550°C at a heating rate of 3-8°C / min, calcining at 500-550°C for 1.5-2.5 h, and then naturally cooling to room temperature, followed by grinding to obtain powdered graphitic carbon nitride. A suitable calcination temperature contributes to the formation of graphitic carbon nitride and improves its photocatalytic performance. Excessive temperature leads to a reduction in active sites and a decrease in photocatalytic performance, while excessively low temperature results in incomplete reaction. A suitable calcination time ensures that the raw materials react fully and are converted into graphitic carbon nitride. Too short a time will result in an incomplete reaction, while too long a time will lead to a decrease in photocatalytic performance.

[0035] According to an embodiment of the present invention, the manganese oxide is obtained by mixing and calcining manganese dioxide and manganese tetroxide. The calcination temperature for forming the manganese oxide is 120-200°C, and the calcination time is 8-16 hours. Specifically, the preparation method includes: mixing manganese dioxide and manganese tetroxide at a mass ratio of 0-1 and adding them to deionized water, stirring magnetically at 30°C for 60-90 minutes; and calcining at 120-200°C for 8-16 hours. Calcination within a suitable temperature range helps in the formation of the manganese oxide and improves its photocatalytic performance. Too low a temperature will lead to incomplete reaction, while too high a temperature will lead to crystal structure damage and decreased photocatalytic performance. A suitable calcination time ensures that the raw materials react fully and are converted into manganese oxide. Too short a time will lead to incomplete reaction, while too long a time will increase energy consumption and cost.

[0036] According to embodiments of the present invention, manganese dioxide is obtained by mixing and calcining manganese sulfate and potassium permanganate, or by mixing and calcining manganese sulfate and ammonium persulfate. The specific preparation process for obtaining γ-MnO2 by mixing and calcining manganese sulfate and potassium permanganate is as follows: manganese sulfate and potassium permanganate are mixed at a mass ratio of 5:1 and added to deionized water, and magnetically stirred at 30°C for 30-60 min to form a homogeneous mixed solution; then the mixed solution is maintained at 120-200°C for 8-16 h; after the reaction, the mixture is washed 3-5 times by centrifugation with water and anhydrous ethanol, and then dried at 60-100°C for 6-12 h; after drying, it is calcined at 280-330°C for 6-9 h to obtain γ-MnO2. β-MnO2 is obtained by mixing and calcining manganese sulfate and ammonium persulfate. The specific preparation process is as follows: manganese sulfate and ammonium persulfate are added to deionized water at a mass ratio of 1.5:1, and the mixture is magnetically stirred for 30-60 minutes to form a homogeneous solution. This solution is then maintained at 120-200℃ for 8-16 hours. After the reaction, the mixture is washed 3-5 times with water and anhydrous ethanol, respectively, by centrifugation. After washing, the mixture is dried at 60-100℃ for 6-12 hours. After drying, it is calcined at 130-160℃ for 8-12 hours to obtain β-MnO2. Besides the method mentioned above, other methods for preparing manganese dioxide can also be used, or commercially available manganese dioxide can be used.

[0037] According to embodiments of the present invention, manganese oxide, graphitic carbon nitride, and activated carbon are mixed and calcined to obtain an air purification precursor material. The method further includes: mixing manganese dioxide and manganese tetroxide, graphitic carbon nitride, and activated carbon, and calcining at 120-200°C for 8-16 hours, during which manganese oxide is formed, thereby forming a heterojunction between the manganese oxide and graphitic carbon nitride; or mixing manganese oxide, urea or melamine, and activated carbon, and calcining at 500-550°C. For 1.5-2.5 hours, graphitic carbon nitride is formed during calcination, which in turn forms a heterojunction between manganese oxides and graphitic carbon nitride; or manganese dioxide and manganese tetroxide, urea or melamine, and activated carbon are mixed and calcined at 120-200℃ for 8-16 hours, and then calcined at 500-550℃ for 1.5-2.5 hours. During calcination, manganese oxides are formed first, then graphitic carbon nitride is formed, and finally a heterojunction between manganese oxides and graphitic carbon nitride is formed.

[0038] In embodiments of the present invention, in addition to activated carbon, common volatile organic compound adsorbent materials, including novel porous carbon materials, zeolite molecular sieves, clay-based adsorbents, metal-organic frameworks, and mesoporous silica, can also be used.

[0039] As a third aspect of the present invention, an application of an adsorption and photocatalytic synergistic air purification material in air purification is provided.

[0040] In this embodiment of the invention, a periodic acid layer adsorbs water vapor from the air, forming an in-situ water layer (self-wetting layer) on the surface of the air purification material, creating a unique three-phase system of air / water / air purification material. The in-situ water layer adsorbs hydrophilic volatile organic compounds (VOCs), and activated carbon adsorbs these VOCs from the water layer, providing more reaction sites for the oxidative decomposition of these compounds by manganese oxides and graphitic carbon nitride. Under light irradiation, the heterojunction formed by the manganese oxides and graphitic carbon nitride generates superoxide radicals, oxidizing and decomposing the adsorbed hydrophilic VOCs into carbon dioxide and water. By utilizing the synergistic effect of adsorption and photocatalysis, the purification efficiency of the air purification material can be effectively improved, achieving a more economical, efficient, and selective air purification effect.

[0041] According to embodiments of the present invention, air purification materials are used for purifying gaseous aldehydes and ketones in indoor odorous environments. Preferably, the concentration of gaseous aldehydes and ketones is 5-50 ppm. Gaseous aldehydes and ketones include any one or more of formaldehyde, acetaldehyde, propionaldehyde, pentanal, octanal, acrolein, and acetone. Formaldehyde, acetaldehyde, propionaldehyde, pentanal, octanal, acrolein, and acetone all have a certain degree of hydrophilicity and can be adsorbed by an in-situ aqueous layer formed by periodic acid.

[0042] The present invention will be further illustrated below through embodiments and related test experiments. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict. All instruments, consumables, and reagents used in the following embodiments are commercially available unless otherwise specified.

[0043] Example 1

[0044] In this embodiment 1, an air purification material was prepared. The specific operation steps are as follows.

[0045] Preparation of graphitic carbon nitride: 1g of urea was placed in a ceramic crucible (the urea should not exceed half the volume of the crucible), the crucible was covered and wrapped with aluminum foil, and then placed in a muffle furnace for calcination. The temperature was increased from room temperature to 550℃ at a rate of 5℃ / min, and calcined at this temperature for 2.5h. After natural cooling to room temperature, the crucible was ground to obtain graphitic carbon nitride, i.e., g-C3N4.

[0046] Preparation of air purification precursor materials: g-C3N4, MnO2, Mn3O4, and activated carbon (AC) were mixed in deionized water and magnetically stirred at 30℃ for 2 hours; after being placed in an oven at 200℃ for 8 hours, they were naturally cooled to room temperature. During the calcination process, MnO2 and Mn3O4 formed manganese oxides (MnO... x Manganese oxides form heterojunctions with graphitic carbon nitride and adhere to the inner and outer surfaces of activated carbon, thereby obtaining the air purification precursor material, namely AC@g-C3N4 / MnO. x The weight ratio of g-C3N4, MnO2, and Mn3O4 is 1:1:1, the activated carbon is sieved to a size of 40-50 mesh, and the amount of activated carbon added is 5 wt% of the air purification precursor material.

[0047] Preparation of air purification materials: 1g AC@g-C3N4 / MnO x Add the mixture to 10 mL of 8 wt% periodic acid (PA) solution, then add 5 mL of deionized water. Stir magnetically at 30 °C for 1 h. After drying, an air purification material consisting of a periodic acid layer forming a heterojunction of manganese oxides, graphitic carbon nitride, and activated carbon is obtained, namely AC@g-C3N4 / MnO. x (PA).

[0048] Example 2

[0049] The preparation method of the air purification material in Example 2 is the same as that in Example 1, except that the amount of activated carbon added is 10 wt% of the air purification precursor material.

[0050] Example 3

[0051] The preparation method of the air purification material in Example 3 is the same as that in Example 1, except that the amount of activated carbon added is 12.5 wt% of the air purification precursor material.

[0052] Example 4

[0053] The preparation method of the air purification material in Example 4 is the same as that in Example 1, except that the amount of activated carbon added is 15 wt% of the air purification precursor material.

[0054] Example 5

[0055] The preparation method of the air purification material in Example 5 is the same as that in Example 1, except that the amount of activated carbon added is 20 wt% of the air purification precursor material.

[0056] Example 6

[0057] The preparation method of the air purification material in Example 6 is the same as that in Example 1, except that the amount of activated carbon added is 25 wt% of the air purification precursor material.

[0058] Example 7

[0059] The preparation method of the air purification material in Example 7 is the same as that in Example 1, except that the amount of activated carbon added is 62.5 wt% of the air purification precursor material.

[0060] Example 8

[0061] The preparation method of the air purification material in Example 8 is the same as that in Example 1, except that the weight ratio of g-C3N4, MnO2, Mn3O4 and activated carbon is 1:5:1:1.

[0062] Example 9

[0063] The preparation method of the air purification material in Example 9 is the same as that in Example 1, except that the weight ratio of g-C3N4, MnO2, Mn3O4 and activated carbon is 1:1:5:1.

[0064] Example 10

[0065] The preparation method of the air purification material in Example 10 is the same as that in Example 1, except that the weight ratio of g-C3N4, MnO2, Mn3O4 and activated carbon is 5:1:1:1.

[0066] Comparative Example 1

[0067] Comparative Example 1 prepared graphitic carbon nitride, and the specific operation steps are as follows.

[0068] 1g of urea was placed in a ceramic crucible (the urea should not exceed half the volume of the crucible), the crucible was covered and wrapped with aluminum foil, and then placed in a muffle furnace for calcination. The temperature was increased from room temperature to 550℃ at a rate of 5℃ / min, and calcined at this temperature for 2.5h. After natural cooling to room temperature, the crucible was ground to obtain graphitic carbon nitride, i.e., g-C3N4.

[0069] Comparative Example 2

[0070] Comparative Example 2 uses g-C3N4 from Comparative Example 1 to prepare periodic acid-encapsulated graphitic carbon nitride. The specific operation steps are as follows.

[0071] 1 g g-C3N4 was added to 10 mL of 8 wt% PA solution, followed by 5 mL of deionized water. The mixture was magnetically stirred at 30 °C for 1 h and dried to obtain graphitic carbon nitride coated with periodic acid, i.e., g-C3N4 (PA).

[0072] Comparative Example 3

[0073] Comparative Example 3 and Example 1 both use AC@g-C3N4 / MnO x The preparation method is the same, the difference being that no activated carbon component is added, and the resulting product is g-C3N4 / MnO. x .

[0074] Comparative Example 4

[0075] Comparative Example 4 utilizes the g-C3N4 / MnO from Comparative Example 3. x periodic acid-coated g-C3N4 / MnO were prepared. x The specific operating steps are as follows.

[0076] 1g g-C3N4 / MnO x Add to 10 mL of 8 wt% PA solution, then add 5 mL of deionized water, stir magnetically at 30 °C for 1 h, and dry to obtain g-C3N4 / MnO coated with periodic acid. x That is, g-C3N4 / MnO x (PA).

[0077] Testing and Characterization:

[0078] The samples obtained from the above embodiments and comparative examples were subjected to relevant tests and characterization.

[0079] Figure 1 This is a scanning electron microscope image of the activated carbon in Example 1 of the present invention. Figure 2 This is a scanning electron microscope image of graphitic carbon nitride in Comparative Example 1 of this invention. Figure 3 This is a scanning electron microscope image of the air purification material in Embodiment 1 of the present invention.

[0080] from Figures 1-3 It can be seen that the curled g-C3N4 nanosheets and granular MnO x g-C3N4 / MnO x MnO is wrapped around the inner and outer surfaces of AC. x Concentrated on the outer surface, its distribution suppresses the accumulation of g-C3N4. When doped with MnO... x At this time, the AC structure becomes smaller, and the particles approach spherical shape. Furthermore, some g-C3N4 / MnO... x Molecular deposition within the internal pores of AC indicates g-C3N4 / MnO x It not only covers the surface of AC, but also enters the pores and anchors to the inner surface of AC.

[0081] Figure 4 The nitrogen adsorption-desorption curves are for activated carbon in Example 1 of the present invention, air purification precursor materials in Examples 1, 3, and 5, and graphitic carbon nitride in Comparative Example 1.

[0082] from Figure 4 It can be seen that, with AC@g-C3N4 / MnO x As the AC ratio in (PA) increases from 5% to 20%, the hysteresis curve shifts towards a region of lower relative pressure, and its width widens, indicating the formation of numerous mesoporous structures (2-50 nm) in the air purification material. Specifically, the hysteresis curve (or isothermal adsorption curve) describes the adsorption behavior of a material for gases as a function of relative pressure. When the hysteresis curve shifts towards a region of lower relative pressure, it means that the test sample has begun to exhibit significant gas adsorption at lower relative pressures. This is related to the presence of numerous mesoporous structures in the test sample, as these structures have a large specific surface area and good gas diffusion properties, allowing for effective gas adsorption even at lower relative pressures. The width of the hysteresis curve reflects the range of gas adsorption during adsorption and desorption. A wider hysteresis curve indicates a larger variation in gas adsorption during adsorption and desorption, which is related to the presence of more pore structures or a wider pore size distribution in the test sample. A wider hysteresis curve indicates the formation of numerous mesoporous structures in the test sample. These mesoporous structures not only possess a large specific surface area but also facilitate the diffusion and transport of gas molecules, thereby improving the photocatalytic performance of the test samples. Mesoporous structures play a crucial role in photocatalysts. First, they provide more reactive sites, which is beneficial for photocatalytic reactions. Second, mesoporous structures facilitate the diffusion and transport of reactants and products, reducing mass transfer resistance and improving photocatalytic efficiency. Furthermore, mesoporous structures can enhance the absorption and utilization of light by the photocatalyst, further improving its photocatalytic performance. In Example 3, AC@g-C3N4 / MnO...x BET specific surface area and pore volume (476.9 m²) 2 / g, 0.306cm 3 The BET specific surface area and pore volume (14.4 m³ / g) of g-C3N4 in Comparative Example 1 were compared with those of g-C3N4 in Comparative Example 1. 2 / g, 0.053cm 3 The increase in AC@g-C3N4 / MnO compared to Example 3 indicates that the AC@g-C3N4 / MnO content is significantly higher. x It has a stronger adsorption capacity compared to g-C3N4 in Comparative Example 1.

[0083] Furthermore, to test the purification capacity of the samples obtained from the above embodiments and comparative examples for acetaldehyde in the air, the following tests were conducted.

[0084] Figure 5 This is a schematic diagram of a continuous flow pipeline system used to test the acetaldehyde purification capacity in an embodiment of the present invention. The initial concentration of acetaldehyde during the test is 3.5 mg / m³. 3 The flow rate was 0.5 L / min, and the illumination time was 1 hour.

[0085] Figure 6 for Figure 5 A schematic diagram of the glass fiber filter membrane groove required for loading test materials in the catalytic reaction chamber of a continuous flow pipeline system. Specifically, the loading method for the glass fiber filter membrane groove is as follows: the test sample is dissolved in deionized water, poured into the glass fiber filter membrane groove, placed in the continuous flow pipeline system, and purged with clean air until no obvious water droplets adhere; wherein, the bottom area of ​​the glass fiber filter membrane groove is 0.02-0.2 m². 2 The clean air purging flow rate is 0.1-5 L / min, and the purging method is by external mechanical devices (manual fans, blowers) or a continuous flow pipeline system. Alternatively, the test sample can be directly coated into the grooves of the glass fiber filter membrane. The above-mentioned wet loading method can ensure that the test sample is uniformly loaded on the glass fiber filter membrane, effectively improving the problem of uneven powder coating by manual application.

[0086] Figure 7 The graph shows the acetaldehyde removal performance test results of Comparative Examples 1-4 and Example 10 of this invention. Figure 8 The graph shows the test results of acetaldehyde adsorption performance in Examples 1-5 and Comparative Example 1 under continuous flow dark environment. Figure 9 The graph shows the acetaldehyde removal performance test results of Examples 1-10 and Comparative Example 4 of the present invention.

[0087] from Figure 7 The ranking of acetaldehyde removal efficiency among different air purification materials can be seen as follows: AC@g-C3N4 / MnO x(PA)>g-C3N4 / MnOx (PA)>g-C3N4 / MnO x >g-C3N4(PA) >g-C3N4. From Figure 8 It can be seen that with the increase of activated carbon content (5%, 10%, 12.5%, 15%, 20%), the total adsorption capacity of the air purification material increases by 3.5-4.2 times compared to g-C3N4. From... Figure 9 It can be seen that in Example 10, AC@g-C3N4 / MnO x The acetaldehyde removal rate of (PA) can reach 91.9%, while the acetaldehyde removal rate of g-C3N4 in Comparative Example 1 is only 49%. Adding only 5% AC can significantly improve the acetaldehyde removal rate of the air purification material, which is 1.69 times that of the air purification material without AC. With the increase of activated carbon content, acetaldehyde removal initially increases and then decreases; the optimal addition ratio of activated carbon is 5-15%. The acetaldehyde removal rate of the air purification material of this invention reaches its highest value when the AC content is 12.5%. Among different main components, AC@g-C3N4 / MnO in Example 10... x The removal rate was significantly higher than that of AC@g-C3N4 / MnO in other embodiments. x In a continuous flow system, the removal rate is highest, reaching 91.9%, when g-C3N4:MnO2:Mn3O4:AC = 5:1:1:1.

[0088] In summary, it can be seen that the air purification material AC@g-C3N4 / MnO of the present invention... x (PA) can achieve the application goal of more economical, efficient and selective degradation of gaseous aldehyde and ketone pollutants in indoor odor environments, and solve the technical defects of existing photocatalytic materials with low photodegradation efficiency of single catalysts and inability to selectively degrade single types of pollutants.

[0089] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A synergistic air purification material combining adsorption and photocatalysis, characterized in that, The air purification material includes: manganese oxides, graphitic carbon nitride, activated carbon, and periodic acid layer; The manganese oxide compound forms a heterojunction with the graphitic carbon nitride and is attached to the inner and outer surfaces of the activated carbon. The periodic acid layer encapsulates the manganese oxide compound, the graphitic carbon nitride, and the activated carbon that form the heterojunction. The manganese oxide compound has a size of 10-300 nm, the graphitic carbon nitride has a size of 10-300 nm, and the activated carbon has a size of 150-425 μm. The amount of activated carbon added is 5-15 wt% of the air purification precursor material, which is obtained by mixing and calcining manganese oxide, graphitic carbon nitride and activated carbon.

2. A method for preparing the air purification material with synergistic adsorption and photocatalysis as described in claim 1, characterized in that, include: Manganese oxides, graphitic carbon nitride, and activated carbon are mixed and calcined to obtain an air purification precursor material. The air purification precursor material is immersed in periodic acid solution and dried to obtain the air purification material.

3. The method according to claim 2, characterized in that, The periodic acid loading on the air purification material is 30-50%.

4. The method according to claim 2, characterized in that, Manganese oxides, graphitic carbon nitride, and activated carbon are mixed and calcined to obtain an air purification precursor material, including: Manganese oxides, graphitic carbon nitride, and activated carbon are mixed and calcined at 320-370℃ for 2.5-4 hours.

5. The method according to claim 4, characterized in that, The graphitic carbon nitride is obtained by calcining urea or melamine, and the calcination temperature for forming the graphitic carbon nitride is 500-550℃, and the calcination time is 1.5-2.5h. The manganese oxide compound is obtained by mixing and calcining manganese dioxide and manganese tetroxide. The calcination temperature for forming the manganese oxide compound is 120-200℃, and the calcination time is 8-16h. The manganese dioxide is obtained by mixing and calcining manganese sulfate and potassium permanganate, or by mixing and calcining manganese sulfate and ammonium persulfate.

6. The method according to claim 2, characterized in that, A manganese oxide compound, graphitic carbon nitride, and activated carbon are mixed and calcined to obtain an air purification precursor material, which also includes: Manganese dioxide, manganese tetroxide, graphitic carbon nitride, and activated carbon are mixed and calcined at 120-200℃ for 8-16 hours; or Mix manganese oxide, urea or melamine, and activated carbon, and calcine at 500-550℃ for 1.5-2.5 hours; or Manganese dioxide, manganese tetroxide, urea or melamine, and activated carbon are mixed and calcined at 120-200℃ for 8-16 hours, and then calcined at 500-550℃ for 1.5-2.5 hours.

7. The application of the air purification material as described in claim 1 in air purification.

8. The application according to claim 7, characterized in that, The air purification material is used to purify gaseous aldehydes and ketones in indoor odorous environments.

9. The application according to claim 8, characterized in that, The gaseous aldehyde and ketone pollutants include any one or more of formaldehyde, acetaldehyde, propionaldehyde, pentanal, octanal, acrolein, and acetone.

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