Aerogel composite purification material as well as preparation method and application thereof

Abstract

The invention provides an aerogel composite purification material as well as a preparation method and application thereof. According to the preparation method, medulla stachyuri is used as a raw material, the aerogel composite purification material can be prepared through alkali liquor dipping, amino modification, MOFs in-situ growth and directional freeze-drying forming treatment in sequence, all the steps are matched with one another to form a graded porous structure, pyridine ring groups, pyrrole ring groups and active metal ions are introduced, the several components have a synergistic effect, and the purification effect is good. The purifying material can efficiently adsorb air pollutants, such as benzene and benzene series, formaldehyde, trichloroethylene, tetrachloroethylene, nitrogen oxide, CO, ammonia, nicotine and the like. The invention provides the aerogel composite purification material prepared by the preparation method. The invention also provides an application of the aerogel composite purification material as an adsorption material in air purification so as to realize effective removal of indoor air pollutants.

Description

Technical Field

[0001] The present invention belongs to the field of air pollutant purification, and particularly relates to an aerogel composite purification material, a preparation method thereof and an application thereof. Background Art

[0003] At present, the most widely used indoor air purification technology is the adsorption technology. The adsorption technology has the advantages of strong applicability, simple design and operation, relatively low cost, etc. The key of the adsorption technology lies in the adsorption purification material, and its performance directly affects the air purification effect. Common adsorption purification materials include activated carbon, molecular sieve, etc., which have the advantages of large specific surface area and low cost, and can effectively adsorb air pollutants to a certain extent. However, these materials also have many deficiencies, such as limited adsorption capacity, insufficient adsorption universality and easy desorption to cause secondary pollution, etc.

[0004] Chinese Patent Application CN112892489 A discloses a MOFs / carbon aerogel adsorption and filtration material and a preparation method thereof, which mainly loads MOFs materials in the structure of carbon aerogel to solve the technical problem that the carbon aerogel material is easy to collapse. In order to increase the loading of MOFs materials, proteins are used as induction, and small molecule organic ligands, metal ions and proteins biomineralize to form MOFs nanocrystalline materials. Part of the protein macromolecule is used as the macromolecular organic ligand of MOFs, and part of it exists in the porous framework of MOFs through weak interactions. The obtained loaded MOFs / carbon aerogel composite material has excellent adsorption and filtration performance. The main purpose of the above-mentioned patent application is to improve the mechanical properties of carbon aerogel, so that the aerogel is not easy to collapse after compression, and the reuse times of the material can be increased; it does not reflect the specific adsorption effect on indoor air pollutants, and does not involve the adsorption of characteristic flue gas in a smoking room. With the continuous improvement of people's requirements for indoor air quality, traditional adsorption purification materials are difficult to meet the increasingly strict air purification requirements, especially difficult to meet the air purification requirements of smoking rooms. Summary of the Invention

[0005] In view of this, the first object of the present invention is to provide a preparation method of an aerogel composite purification material. The preparation method uses Tetrapanax papyriferus as a raw material, and can obtain the aerogel composite purification material through alkali solution impregnation, amino modification, in-situ growth of MOFs and directional freeze-drying forming treatment in sequence. Each step cooperates with each other to form a hierarchical pore structure and introduce pyridine ring groups, pyrrole ring groups and active metal ions. The synergistic effect of these makes the purification material capable of efficiently adsorbing air pollutants, such as benzene and benzene series, formaldehyde, trichloroethylene, tetrachloroethylene, nitrogen oxides, CO, ammonia, nicotine, etc.

[0006] The second object of the present invention is to provide an aerogel composite purification material prepared by the above preparation method.

[0007] The third object of the present invention is to provide an air purification and filtration component using the above aerogel composite purification material, and further provide an air purifier to effectively remove indoor air pollutants.

[0008] In order to achieve the above objects, the technical solutions adopted by the present invention are as follows: A preparation method of an aerogel composite purification material, comprising the steps of: Alkali solution impregnation: Impregnating Tetrapanax papyriferus with an alkali solution to obtain alkali-activated Tetrapanax papyriferus; Amino modification: Under the action of a catalyst, the cellulose in the alkali-activated Tetrapanax papyriferus undergoes an esterification reaction with an amino acid hydrochloride to obtain amino-modified Tetrapanax papyriferus; In-situ growth of MOFs: The amino-modified Tetrapanax papyriferus, a first metal salt, and an aminopyridine carboxylic acid ligand are subjected to in-situ growth of MOFs to obtain an MOFs-Tetrapanax papyriferus composite material; Directional freeze-drying forming: Uniformly dispersing a tetraphenylporphyrin metal salt powder in a polyvinylpyrrolidone solution to form a mixed gel solution; arranging the MOFs-Tetrapanax papyriferus composite material in a mold, and adding the mixed gel solution to the mold; performing freeze forming to obtain the aerogel composite purification material.

[0009] The main purpose of the alkali solution impregnation is to swell or dissolve some impurities such as lignin and hemicellulose that connect fibers in Tetrapanax papyriferus, weaken the binding force between Tetrapanax papyriferus fibers, make the original dense fiber structure become loose, increase the number of pores, provide a passage for gas transmission, enhance the physical interception of air pollutants, and be more conducive to subsequent modification treatment. In addition, the alkali solution impregnation treatment can enhance the activity of some hydroxyl groups in the Tetrapanax papyriferus structure, enabling the hydroxyl groups that were originally difficult to participate in the reaction to more smoothly combine with the corresponding reactant groups.

[0010] However, when the alkali concentration is low or the impregnation time is short, the structural effect on Tetrapanax papyriferus is not obvious. When the alkali concentration is too high or the impregnation time is too long, the fiber structure of Tetrapanax papyriferus may be damaged, and a large amount of cellulose therein is hydrolyzed, resulting in too large pores in Tetrapanax papyriferus, which is not conducive to the interception of air pollutants. Therefore, the mass fraction of the alkali solution can be 1% to 8%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, etc., preferably 1% to 4%; the impregnation time is preferably 20 to 60 min, such as 20 min, 30 min, 40 min, 50 min, 60 min, etc. The alkali solution can be a strong alkaline solution such as a sodium hydroxide solution or a potassium hydroxide solution.

[0011] Specifically, the step of alkali solution impregnation includes: placing Tetrapanax papyriferus in an alkali solution with a mass fraction of 1% - 8% and soaking it at room temperature for 20 - 60 min, while stirring to ensure full contact between the alkali solution and Tetrapanax papyriferus, followed by washing and drying to obtain the alkali-activated Tetrapanax papyriferus. Among them, in this step, the material-liquid ratio of Tetrapanax papyriferus to the alkali solution is 1 : 35 - 45 g / mL.

[0012] Before the step of alkali solution impregnation, there is also a pre-treatment step: ultrasonic washing, drying, and cutting Tetrapanax papyriferus raw materials with an aqueous ethanol solution into a preset size. The main purpose of this pre-treatment step is to use the ethanol solution to dissolve and remove foreign substances attached to the surface of the natural plant Tetrapanax papyriferus, playing a cleaning role to make the Tetrapanax papyriferus raw materials purer and avoiding the influence of impurities during subsequent processing; in addition, Tetrapanax papyriferus may contain some fat-soluble impurities, and the ethanol solution can dissolve and remove some of them during washing, which is more conducive to subsequent modification. The mass fraction of the aqueous ethanol solution is 30 - 70%, such as 30%, 40%, 50%, 60%, 70%, etc., and the ultrasonic washing time is 15 - 60 min, such as 15 min, 30 min, 45 min, 60 min, etc. The preferred length of the cut Tetrapanax papyriferus is 1 - 3 cm, such as 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, for use as an adsorption and filtration material for air purifiers. Preferably, the material-liquid ratio of Tetrapanax papyriferus raw materials to the aqueous ethanol solution is 1 : 45 - 55 g / mL.

[0013] The main purpose of the amino modification step is to introduce the functional functional group amino onto Tetrapanax papyriferus, facilitating the subsequent in-situ generation of MOFs. In this step, amino acid hydrochloride can efficiently catalyze the esterification reaction and has the ability to bind and break hydrogen bonds, enabling the alkali-activated Tetrapanax papyriferus to undergo an esterification reaction with amino acid hydrochloride, thereby introducing the functional functional group amino into its structure. When adding metal salts and ligands for the in-situ growth of MOFs subsequently, it plays a role in immobilizing metal ions, which is more conducive to the chemical adsorption of air pollutants. If the dosage of amino acid hydrochloride is too small, it is not conducive to the subsequent in-situ growth of MOFs; if the dosage is too large, the system concentration increases, which may lead to a decrease in reaction efficiency, both of which will affect the adsorption of the product to the target pollutant. The amino acid hydrochloride compounds can be alanine hydrochloride or aspartic acid hydrochloride.

[0014] The catalyst is preferably a Lewis acid metal salt catalyst, which can form a coordination bond with the hydroxyl groups in the structure of Tetrapanax papyriferus, activate the hydroxyl groups, and thus promote the esterification reaction between cellulose and amino acid hydrochloride. When the amount of the catalyst is small, it is difficult to fully activate the hydroxyl groups in Tetrapanax papyriferus. However, when the amount is large, the excessive metal ions may undergo additional coordination reactions with some functional groups in Tetrapanax papyriferus, etc., thereby consuming the reactants and leading to a decrease in the reaction efficiency. Therefore, the mass ratio of the alkali-activated Tetrapanax papyriferus, amino acid hydrochloride, and catalyst is preferably 10:(3 - 12):(0.6 - 2.4), such as 10:3:0.6, 10:5:0.6, 10:7.5:0.6, 10:9:0.6, 10:12:0.6, 10:3:1.5, 10:5:1.5, 10:7.5:1.5, 10:9:1.5, 10:12:1.5, 10:3:2.4, 10:5:2.4, 10:7.5:2.4, 10:9:2.4, 10:12:2.4, etc. Preferably, the catalyst is zinc chloride. The reaction temperature is preferably 60 - 110°C, such as 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, etc.; the reaction time is preferably 1 - 4 h, such as 1 h, 2 h, 3 h, 4 h, etc.

[0015] Specifically, the step of amino modification includes: fully shaking and mixing the alkali-activated Tetrapanax papyriferus, the catalyst, amino acid hydrochloride, and deionized water, carrying out an esterification reaction at a temperature of 60 - 110°C for 1 - 4 h, washing and drying to obtain the amino-modified Tetrapanax papyriferus. Among them, in this step, the material-liquid ratio of the alkali-activated Tetrapanax papyriferus and deionized water is 1:35 - 45 g / mL.

[0016] In the step of in-situ growth of the MOFs, the amino-pyridine carboxylic acid ligands and metal ions are the main raw materials for synthesizing MOFs. The pyridine ring in the amino-pyridine carboxylic acid ligands can have a conjugation effect with benzene series, trichloroethylene, tetrachloroethylene, nicotine, etc., and has a good adsorption effect on various air pollutants. The amino group in the amino-modified stachyurus medulla can immobilize metal ions by complexation reaction with the metal ions in the MOFs, creating favorable conditions for the in-situ growth of MOFs. Therefore, if the dosage of the first metal ion is too small, it may cause limited in-situ growth of MOFs; if the dosage is too large, it may cause partial self-growth of MOFs and failure to be immobilized on the modified stachyurus medulla, affecting the adsorption effect of the purification material on pollutants. Therefore, the mass ratio of the amino-modified stachyurus medulla, amino-pyridine carboxylic acid ligands, and the first metal salt is preferably 10:(0.6 - 2.5):(2.2 - 12.5), such as 10:0.6:2.2, 10:0.6:4, 10:0.6:6, 10:0.6:8, 10:0.6:10, 10:0.6:12.5, 10:1:2.2, 10:1:4, 10:1:6, 10:1:8, 10:1:10, 10:1:12.5, 10:1.5:2.2, 10:1.5:4, 10:1.5:6, 10:1.5:8, 10:1.5:10, 10:1.5:12.5, 10:2:2.2, 10:2:4, 10:2:6, 10:2:8, 10:2:10, 10:2:12.5, 10:2.5:2.2, 10:2.5:4, 10:2.5:6, 10:2.5:8, 10:2.5:10, 10:2.5:12.5, etc.

[0017] The first metal salt can be a soluble metal salt, including copper salts, iron salts, zinc salts, such as copper sulfate, iron sulfate, zinc sulfate, etc.; the amino-pyridine carboxylic acid ligands can be 6-aminonicotinic acid, 5,6-diaminonicotinic acid, etc. The reaction temperature is preferably 35 - 60 °C, such as 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, etc., and the reaction time is preferably 1 - 6 h.

[0018] Specifically, the step of in-situ growth of the MOFs includes: first placing the amino-modified stachyurus medulla in an aqueous solution of the first metal salt, adding the amino-pyridine carboxylic acid ligands, heating and stirring until the amino-pyridine carboxylic acid ligands are completely dissolved, cooling and then transferring to a microwave reactor for in-situ growth of MOFs at 35 - 60 °C and 80 - 350 W, filtering, washing, and vacuum drying to obtain the MOFs-stachyurus medulla composite material. Among them, the material-liquid ratio of the amino-modified stachyurus medulla and the aqueous solution of the first metal salt is 1:28 - 32 g / mL.

[0019] To promote the growth and perfection of MOFs material crystals, reduce the structural defects inside the material, thereby regulating the crystal structure and pore structure of the material, enhancing the stability of the MOF material, and increasing the reaction yield, staged reactions can be adopted to facilitate the adjustment of reaction conditions according to different reaction stages. The in-situ growth reaction of MOFs carried out in the microwave reactor is divided into two stages: the first stage is the preheating stage. In this stage, under the action of microwaves, the reaction system rapidly heats up, the molecular movement speed increases, and the ligands and metal ions are in full contact in the solution, which is more conducive to the formation of MOFs crystals with uniform size and regular structure; in addition, microwave preheating can initially activate the reactant molecules, and this activated state can reduce the activation energy of the reaction, making the subsequent coordination reaction easier to occur, increasing the reaction rate, and by raising the temperature of the reaction system to a certain extent in the preheating stage, the entire reaction environment can be made more stable; therefore, the microwave power in this stage is preferably set to 80 - 120 W, and the reaction time is 10 - 40 min; the second stage is the formal reaction stage. In this stage, the microwave power is preferably set to 250 - 350 W, and the reaction time is 1 - 5 h.

[0020] In the step of the directional freeze-drying forming, the polyvinylpyrrolidone solution is a gel solution, which serves as a shaping medium and can endow the prepared composite purification material with a specific shape and structure. By controlling the concentration of the polyvinylpyrrolidone solution, the pore size of the composite purification material is adjusted to provide a passage for gas transmission, improving the physical interception and chemical adsorption of the material for air pollutants. When the concentration of the polyvinylpyrrolidone solution is too small, the polymer molecular chains in the solution are relatively dispersed and it is difficult to form a stable network structure. At this time, the pores are too large, the gas diffuses too fast, which is not conducive to the adsorption of air pollutants by the material, and the mechanical properties and stability are not high; when the solution concentration is too large, the formed gel network is too dense, which will affect the gas diffusion and may block the original pores of the MOFs - Tetrapanax papyriferus composite material, thus affecting the adsorption effect of the material on air pollutants. Therefore, the mass fraction of the polyvinylpyrrolidone solution can be 4% - 20%, preferably 5% - 15%, such as 5%, 7%, 8%, 9%, 11%, 13%, 15%, etc.

[0021] The tetraphenylporphyrin metal salt has hydrophobicity. When it is evenly distributed in the pores and on the surface of the aerogel, it occupies a part of the space of the aerogel, reducing the contact area between water molecules and the aerogel, thereby improving the hydrophobicity of the aerogel to a certain extent, enhancing the purification performance of the composite purification material, and extending the service life. The tetraphenylporphyrin metal salt is preferably zinc tetraphenylporphyrin, iron tetraphenylporphyrin, copper tetraphenylporphyrin, etc. In this way, the metal ions at the center of the iron tetraphenylporphyrin have available empty orbitals and can form coordination with nitrogen oxides, CO, ammonia, etc., realizing the adsorption of air pollutants such as nitrogen oxides, CO, and ammonia. The pyrrole ring and benzene ring in its structure can form conjugation with benzene series, trichloroethylene, tetrachloroethylene, nicotine, etc., and have a certain removal effect on various air pollutants. Therefore, the mass ratio of polyvinylpyrrolidone to the tetraphenylporphyrin metal salt is preferably 9-11:0.19-0.21.

[0022] Specifically, the steps of the directional freeze-drying forming include: dissolving polyvinylpyrrolidone in deionized water to prepare the polyvinylpyrrolidone solution, adding the tetraphenylporphyrin metal salt powder to the polyvinylpyrrolidone solution, fully stirring and ultrasonically dispersing the tetraphenylporphyrin metal salt evenly in the gel solution to form the mixed gel solution; first arranging the MOFs-Chinese dove tree bark composite material at the bottom of the mold, then adding the mixed gel solution, and then sealing, freeze-forming, and freeze-drying to form an aerogel, thus obtaining an aerogel composite purification material with a preset specification. Among them, the tetraphenylporphyrin metal salt powder is prepared by ball-milling the tetraphenylporphyrin metal salt to a nanoscale particle size. The placement method of the MOFs-Chinese dove tree bark composite material is that the cut surface contacts the bottom of the mold and is arranged axially, and it can be arranged in 1 layer or multiple layers; the specific addition amount of the mixed gel solution depends on the actual use situation.

[0023] Further, the step of forming the mixed gel solution includes: first adding a second metal salt and an amino compound to the polyvinylpyrrolidone solution and fully dissolving them, then adding the metal salt powder of tetraphenylporphyrin, fully stirring and performing ultrasonic treatment to obtain the mixed gel solution. Among them, the second metal ion is copper ion, iron ion, etc., and the amino compound is urea, biuret, etc. In this step, introducing the second metal ion and the amino compound into the polyvinylpyrrolidone solution increases the overall metal ion and amino content of the material. Part of the amino groups may complex with the second metal ion to form nodes, and part may form intermolecular hydrogen bonds with polyvinylpyrrolidone, playing a role in stabilizing the aerogel network. Moreover, the second metal ion has good antibacterial ability, enabling the purification material to have antibacterial function. In addition, the second metal ion can also have a coordination effect with nitrogen oxides, CO, ammonia, etc., and the amino group can undergo a Schiff base reaction with aldehyde substances such as formaldehyde, thereby playing a certain adsorption role on these pollutants. Therefore, if the addition amounts of the second metal ion and the amino compound are too small, it is difficult to achieve the adsorption effect on air pollutants; if the addition amounts are too large, it will affect the mechanical properties of the aerogel. Therefore, the mass ratio of polyvinylpyrrolidone, the second metal salt, the amino compound-containing material to the metal salt of tetraphenylporphyrin is 9 - 10.5 : 0.8 - 1.2 : 1.8 - 2.1 : 0.19 - 0.21.

[0024] Further, the step of forming the mixed gel solution further includes: adding a fragrance auxiliary to the polyvinylpyrrolidone solution to make the mixed gel solution have a fragrance. Among them, the fragrance auxiliary is a synthetic fragrance such as citral, vanillin, citronellol, menthol, etc., and the addition amount is 0.5 - 1.5% of the total dry mass of other raw materials in the mixed gel solution. In this way, the prepared composite purification material can play the role of an air freshener while adsorbing air pollutants.

[0025] The present invention also provides an aerogel composite purification material prepared by the above preparation method. Among them, the specific surface area of the aerogel composite purification material is 90 - 400 m 2 / g, the pore volume is 0.060 - 0.240 cm 3 / g, and the average pore diameter is 8 - 15 nm.

[0026] The adsorption mechanism of the aerogel composite purification material provided by the present invention is as follows: (1) Physical adsorption: Xiaotongcao is a rod-shaped natural plant material with relatively large pores. Through ultrasonic washing, alkali impregnation, functional modification, and in-situ growth of MOFs, the material is endowed with more micron-sized and nano-sized pores. The aerogel produced by freeze-drying the polyvinylpyrrolidone mixed solution endows the material with micron-sized pores with adjustable size. Eventually, a hierarchical porous composite material is formed, which can fully expose the adsorption sites, provide a pathway for gas transmission, has strong physical adsorption performance, and can effectively adsorb air pollutants such as benzene and benzene series, formaldehyde, trichloroethylene, tetrachloroethylene, nitrogen oxides, CO, ammonia, nicotine, etc.

[0027] (2) Chemical adsorption: The pyridine ring groups and pyrrole ring groups in the composite purification material can have a conjugation effect with benzene series, trichloroethylene, tetrachloroethylene, nicotine, etc., which is beneficial to the removal of various air pollutants. The amino group contained in the biuret introduced into the aerogel can undergo a Schiff base reaction with aldehyde substances such as formaldehyde, greatly enhancing the capture ability of the material for aldehyde substances such as formaldehyde. At the same time, the active metal ions introduced into the material can form a coordination effect with nitrogen oxides, CO, ammonia, etc., and have a certain adsorption effect on these pollutants. In addition, there is a conjugation effect between the pyrrole ring group in polyvinylpyrrolidone and nicotine, and synergistic with the complexation effect of the active metal ions in the material and nicotine, making the material effectively remove nicotine.

[0028] The present invention also provides an application of the above-mentioned aerogel composite purification material in purifying air, wherein the aerogel composite purification material adsorbs at least one of benzene, benzene series, formaldehyde, trichloroethylene, tetrachloroethylene, nitrogen oxides, CO, ammonia, and nicotine in air pollutants. Specifically, the saturated adsorption amounts of the aerogel composite purification material for benzene, toluene, trichloroethylene, formaldehyde, NO, CO, ammonia, and nicotine at normal temperature and pressure are 135 - 550, 100 - 485, 50 - 114, 90 - 245, 35 - 90, 30 - 85, 35 - 96, and 85 - 255 mg / g, respectively.

[0029] The present invention also provides an air purification and filtration component, including the above-mentioned aerogel composite purification material. Among them, the filtration component is a filter element or a filter screen, etc. That is, the aerogel composite purification material can be combined into filtration components such as purification filter elements or filter screens, and can also be used in combination with other filtration components in air purifiers.

[0030] The present invention also provides an air purifier, including the above-mentioned air purification and filtration component.

[0031] Therefore, the above-mentioned composite purification material provided by the present invention is mainly prepared from Tetrapanax papyriferus through steps such as alkali solution impregnation, amino modification, in-situ growth of MOFs, and directional freeze-drying forming treatment. Each step cooperates with each other to form a hierarchical porous structure and introduce pyridine ring groups, pyrrole ring groups, and active metal ions. The synergistic effect of these makes the composite purification material have strong physical adsorption and chemical adsorption properties for air pollutants such as benzene and benzene series, formaldehyde, trichloroethylene, tetrachloroethylene, nitrogen oxides, CO, ammonia, nicotine, etc., and can be used as an adsorption and purification material for indoor air pollutants. In addition, the purification material of the present invention has excellent performance, can effectively remove air pollutants, and at the same time the size of the composite purification material is adjustable, with additional antibacterial and air freshening capabilities, and can be conveniently applied to different purification systems such as air purifiers. Description of the Drawings

[0032] Figure 1 It is a schematic structural diagram of the aerogel composite purification material provided by the embodiment of the present invention. Among them, in the figure: 1 - Tetrapanax papyriferus, 2 - polyvinylpyrrolidone mixed gel. Detailed Embodiments

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0034] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values and individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0035] Unless otherwise specified, the terms used in the present invention are all common terms in the art. For the preparation processes, test methods, etc. used in each embodiment without special description, they are all conventional means well-known to those skilled in the art, and the raw materials and equipment used can be obtained from public commercial channels.

[0036] Examples 1 - 8 Each of Examples 1 - 8 of the present invention provides an aerogel composite purification material, and the preparation method includes the following steps: (1) Pretreatment Take Tetrapanax papyriferus and disperse it in an ethanol aqueous solution with a mass fraction of 50% according to a solid-liquid ratio of 1:50 g / mL, ultrasonically wash for 30 min, dry at 60 °C, and cut into cylindrical shapes with a length of 2 cm to obtain the washed Tetrapanax papyriferus; (2) Alkali solution impregnation Soak the processed Tetrapanax papyriferus after step (1) in sodium hydroxide solution at a solid-liquid ratio of 1:40 g / mL, stir slowly during this period, wash thoroughly with deionized water, and dry at 60 °C to obtain alkali-activated Tetrapanax papyriferus; (3) Amino modification Add the alkali-activated Tetrapanax papyriferus to deionized water at a solid-liquid ratio of 1:40 g / mL, oscillate for 30 min, add a catalyst and continue to oscillate for 15 min, then add aspartic acid hydrochloride, react at 80 °C for 2 h. After the reaction, wash with deionized water and dry at 60 °C to obtain amino-modified Tetrapanax papyriferus; (4)In-situ growth of MOFs Add the amino-modified Tetrapanax papyriferus to copper sulfate solution at a solid-liquid ratio of 1:30 g / mL, then add an aminopyridine carboxylic acid ligand, stir at 50 °C until the ligand dissolves, and transfer to a microwave reaction tube after cooling. The microwave reaction temperature is 45 °C, the stirring rate is 100 r / min, and the reaction is divided into two stages. The first stage is the preheating stage, where the microwave power is set to 100 W and the reaction time is 20 min. The second stage is the formal reaction stage, where the microwave power is set to 300 W and the reaction time is 3 h. After the reaction, cool naturally at room temperature, filter, wash, and vacuum dry the product to obtain the MOFs-Tetrapanax papyriferus composite material; (5)Directional freeze-drying forming Dissolve polyvinylpyrrolidone K60 in deionized water to prepare a polyvinylpyrrolidone (PVP) solution, add copper sulfate and biuret, stir well, then add iron tetraphenylporphyrin powder, stir and ultrasonicate to make it evenly dispersed to obtain a polyvinylpyrrolidone mixed gel solution. Arrange the MOFs-Tetrapanax papyriferus composite material axially at the bottom of a container with a diameter of 10 cm, add the polyvinylpyrrolidone mixed gel solution, seal it, and quickly freeze and form in liquid nitrogen, then freeze-dry to obtain the aerogel composite purification material with specific dimensions as shown in Figure 1 Figure, where the aerogel composite purification material includes a polyvinylpyrrolidone mixed gel 2 with a porous structure and multiple Tetrapanax papyriferus 1 evenly arranged in the polyvinylpyrrolidone mixed gel 2.

[0037] Among them, in Example 8, a fragrance auxiliary citral is added on the basis of Example 5, so that the prepared composite purification material can act as an air freshener while adsorbing air pollutants.

[0038] This step is the experimental scheme for preparing a layer of composite purification material. Further, the composite purification materials can be combined into a purification filter element or a filter mesh device and used in combination with other filter components in an air purifier.

[0039] The material usage of each example is shown in Table 1.

[0040] Table 1 Material Dosage in Examples

[0041] The pore structure of the composite purification material provided in the examples of the present invention was analyzed using a specific surface area and pore size analyzer. The specific surface area of the composite purification materials provided in Examples 1-8 of the present invention was 90-400 m 2 / g, the pore volume was 0.065-0.235 cm 3 / g, and the average pore diameter was 9-14 nm; among them, the specific surface area of the composite purification material provided in Example 5 was 398 m 2 / g, the pore volume was 0.234 cm 3 / g, and the average pore diameter was 9.2 nm. The specific surface area of the composite purification material provided in Example 6 was 379 m 2 / g, the pore volume was 0.218 cm 3 / g, and the average pore diameter was 9.1 nm.

[0042] Example 9 This example provides an aerogel composite purification material, which has basically the same preparation method as the aerogel composite purification material provided in Example 5. The main differences are as follows: in this example, in step (3), alanine hydrochloride is used instead of aspartic acid hydrochloride in the corresponding step of Example 5; in step (4), 5,6-diaminonicotinic acid is used instead of 6-aminonicotinic acid in the corresponding step of Example 5, and zinc sulfate is used instead of copper sulfate in the corresponding step of Example 5; in step (5), ferric sulfate is used instead of copper sulfate in the corresponding step of Example 5, urea is used instead of biuret in the corresponding step of Example 5, and zinc tetraphenylporphyrin is used instead of iron tetraphenylporphyrin in the corresponding step of Example 5; other steps and process parameters remain unchanged.

[0043] Example 10 This example provides an aerogel composite purification material, which has basically the same preparation method as the aerogel composite purification material provided in Example 6. The main differences are as follows: in this example, in step (3), alanine hydrochloride is used instead of aspartic acid hydrochloride in the corresponding step of Example 6; in step (4), ferric sulfate is used instead of copper sulfate in the corresponding step of Example 6; in step (5), ferric sulfate is used instead of copper sulfate in the corresponding step of Example 6, and urea is used instead of biuret in the corresponding step of Example 6; other steps and process parameters remain unchanged.

[0044] Example 11 This embodiment provides an aerogel composite purification material, which has basically the same preparation method as the aerogel composite purification material provided in Embodiment 6. The main difference is that in this embodiment, the mass fraction of the polyvinylpyrrolidone solution in step (5) of Embodiment 6 is adjusted to 20%, and copper sulfate and biuret are not added during the preparation process, and other conditions are the same as those in Embodiment 6.

[0045] Embodiment 12 This embodiment provides an aerogel composite purification material, which has basically the same preparation method as the aerogel composite purification material provided in Embodiment 7. The main difference is that in this embodiment, the mass fraction of the sodium hydroxide solution in step (2) is adjusted to 6%, and other conditions are the same as those in Embodiment 7.

[0046] Each of Comparative Examples 1-5 provides a composite purification material, and its preparation method is basically the same as that of the corresponding embodiment. The main differences are as follows: Comparative Example 1: Step (3) in Embodiment 2 is omitted, and other conditions are the same as those in Embodiment 2.

[0047] Comparative Example 2: The mass ratio of modified tetrapanax papyriferus, ligand, and metal ions in step (4) of Embodiment 1 is adjusted from 10:0.6:2.2 to 10:0.4:2.2, and other conditions are the same as those in Embodiment 1.

[0048] Comparative Example 3: Step (2) in Embodiment 1 is omitted, and other conditions are the same as those in Embodiment 1.

[0049] Comparative Example 4: Step (4) in Embodiment 1 is omitted, and other conditions are the same as those in Embodiment 1.

[0050] Comparative Example 5: Steps (2) and (4) in Embodiment 1 are omitted, and other conditions are the same as those in Embodiment 1.

[0051] Verification of adsorption performance This embodiment provides the applications of the composite purification materials prepared in the above Embodiments 1-10 and the composite purification materials provided in Comparative Examples 1-5 in the preparation of air pollutant purification materials respectively. In this embodiment, by using a multi-component adsorption breakthrough curve analyzer, the adsorption performances of the 15 materials prepared in Embodiments 1-10 and Comparative Examples 1-5 for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine are evaluated to prove that the composite purification material provided in the embodiment of the present invention can be used as an air pollutant purification material and can effectively remove benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine in air pollutants. The method for evaluating the adsorption effect of the purification material provided by the present invention on air pollutants is as follows: Evaluation methods for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, and ammonia: Weigh about 0.2 g of the purified material sample and fill it into a sample tube with an inner diameter of 10 mm. Activate it with nitrogen purge at 50 °C for 120 min, and the purge gas flow rate is 20 SCCM. The experimental conditions are set at normal temperature and pressure. The air pollutant concentration is set at 5000 ppm, the total inlet flow rate is 80 SCCM, and nitrogen is used as the carrier gas and does not participate in adsorption.

[0052] Evaluation method for nicotine: Weigh about 0.2 g of the purified material sample and fill it into a sample tube with an inner diameter of 10 mm. Activate it with nitrogen purge at 50 °C for 120 min, and the purge gas flow rate is 20 SCCM. The experimental conditions are set at normal temperature and pressure. The nicotine concentration is set at 55 ppm, the total inlet flow rate is 80 SCCM, and nitrogen is used as the carrier gas and does not participate in adsorption. The evaluation results are shown in Table 2.

[0053] Table 2 Saturated adsorption capacities of the purified material samples for air pollutants Sample Benzene saturation adsorption capacity Q (mg / g) Toluene saturation adsorption capacity Q (mg / g) Trichloroethylene saturation adsorption capacity Q (mg / g) Formaldehyde saturation adsorption capacity Q (mg / g) NO saturation adsorption capacity Q (mg / g) CO saturation adsorption capacity Q (mg / g) Ammonia saturation adsorption capacity Q (mg / g) Nicotine saturation adsorption capacity Q (mg / g) Example 1 141 103 51 91 35 30 37 87 Example 2 229 201 68 147 53 46 55 136 Example 3 501 449 100 225 81 77 89 236 Example 4 363 319 81 172 64 54 68 174 Example 5 550 479 110 240 86 81 95 246 Example 6 542 455 104 245 90 84 92 250 Example 7 509 419 98 238 85 77 87 241 Example 8 545 481 104 236 87 81 93 243 Example 9 533 468 105 238 83 79 90 243 Example 10 525 437 101 241 86 80 88 244 Example 11 383 326 89 182 72 61 73 188 Example 12 340 292 75 162 61 49 66 167 Comparative Example 1 45 25 18 31 16 14 18 25 Comparative Example 2 99 61 39 58 25 23 31 50 Comparative Example 3 96 59 38 55 24 23 30 47 Comparative Example 4 44 23 18 30 17 15 17 26 Comparative Example 5 43 23 15 29 14 11 15 23 It can be seen from Table 2 that the saturated adsorption capacities of the composite purification materials provided by the embodiments of the present invention for benzene, toluene, trichloroethylene, formaldehyde, NO, CO, ammonia, and nicotine are 135 - 550, 100 - 485, 50 - 114, 90 - 245, 35 - 90, 30 - 85, 35 - 96, and 85 - 255 mg / g, respectively. There are significant differences in the saturated adsorption capacities of the purification materials prepared in different examples and comparative examples for benzene, toluene, trichloroethylene, formaldehyde, NO, CO, ammonia, and nicotine, which are mainly related to the physical and chemical structures of the materials.

[0054] The saturated adsorption capacities of the purification materials provided by Example 11 for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine are respectively lower than those of the purification materials of Example 6. This is mainly because copper ions and biuret are not added to the aerogel, and the superposition of these factors greatly affects the adsorption of air pollutants by the material; in addition, when the concentration of the PVP solution is relatively large, the formed gel network is relatively dense, which affects the diffusion of gas and may block the original pores of the MOFs - Tetrapanax papyriferus composite material.

[0055] The saturated adsorption capacities of the purification materials provided by Example 12 for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine are respectively lower than those of the purification materials of Example 7. This is mainly because when the alkali concentration is relatively large, the fiber structure of Tetrapanax papyriferus may be damaged, and the cellulose therein undergoes hydrolysis, resulting in the fracture and fragmentation of Tetrapanax papyriferus, and then the pores of Tetrapanax papyriferus are too large, which is not conducive to intercepting air pollutants and reduces the adsorption amount of each pollutant.

[0056] Compared with Example 2, the saturation adsorption capacities of the purification material provided in Comparative Example 1 for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine are significantly reduced. This is mainly because the small Tetrapanax papyriferus was not functionally modified. When adding metal salts and ligands for in-situ growth of MOFs subsequently, metal ions could not be effectively immobilized on the small Tetrapanax papyriferus, and in-situ growth of MOFs could not be effectively carried out, resulting in loss during the post-treatment of MOFs, thus affecting the adsorption of air pollutants by the material.

[0057] Compared with Example 1, the saturation adsorption capacities of the purification material provided in Comparative Example 2 for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine are significantly reduced. This is mainly because the amount of copper ions used is too small, restricting the in-situ growth of MOFs and affecting the adsorption of air pollutants by the material.

[0058] Compared with Example 1, the saturation adsorption capacities of the purification material provided in Comparative Example 3 for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine are significantly reduced. This is mainly because the small Tetrapanax papyriferus was not impregnated and purified with an alkali solution, and the fiber structure of the small Tetrapanax papyriferus is relatively dense, resulting in subsequent modification mainly occurring on the surface of the small Tetrapanax papyriferus. Therefore, both its physical and chemical adsorption capacities are reduced.

[0059] Compared with Example 1, the saturation adsorption capacities of the purification material provided in Comparative Example 4 for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine are significantly reduced. This is mainly because in-situ growth of MOFs was not carried out, reducing the pore structure and the content of effective functional groups in the material.

[0060] Compared with Example 1, the saturation adsorption capacities of the purification material provided in Comparative Example 5 for benzene, toluene, formaldehyde, trichloroethylene, NO, CO, ammonia, and nicotine are significantly reduced. This is mainly because the small Tetrapanax papyriferus was not impregnated and purified with an alkali solution, and the fiber structure of the small Tetrapanax papyriferus is relatively dense, resulting in subsequent modification mainly occurring on the surface of the small Tetrapanax papyriferus. Therefore, both its physical and chemical adsorption capacities are reduced. At the same time, in-situ growth of MOFs was not carried out, reducing the pore structure and the content of effective functional groups in the material. The superposition of these two factors greatly affects the adsorption effect of the material on air pollutants; thus, it is proved that the superposition of alkali solution impregnation and in-situ growth of MOFs on the adsorption effect of the purification material greatly improves the protective adsorption capacity of the purification material for each component in air pollutants.

[0061] Example 13 This example provides an air purification filter element, including the aerogel composite purification material prepared in Example 5. In other examples, the aerogel composite purification material is the aerogel composite purification material provided in any one of Examples 1-4 and 6-12.

[0062] This embodiment also provides an air purification system, including the above-mentioned air purification filter element. Among them, in other embodiments, the air purification filter element in the air purification system can be replaced by an air purification filter screen, and the air purification filter screen is mainly composed of the aerogel composite purification material provided in any one of Embodiments 1-12.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A method for preparing an aerogel composite purification material, comprising the steps of: Alkali solution impregnation: using alkaline solution to impregnate the small tongcao to obtain alkali activated small tongcao; Amino modification: the cellulose in the alkali-activated cyperus rotundus undergoes an esterification reaction with amino acid hydrochloride under the action of a catalyst to obtain amino-modified cyperus rotundus; In-situ growth of MOFs: the amino-modified smilax glabra, the first metal salt and the aminopyridine carboxylic acid ligands are used to perform in-situ growth of MOFs to obtain a MOFs-smilax glabra composite material; Directional freeze-drying molding: evenly dispersing tetraphenylporphyrin metal salt powder in polyvinyl pyrrolidone solution to form a mixed gel solution; directionally arranging the MOFs-Xiaotongcao composite material in a mold, and adding the mixed gel solution into the mold; freeze molding to obtain an aerogel composite purification material.

2. The preparation method according to claim 1, characterized in that: The alkali solution impregnation step comprises: soaking the small tongcao in an alkali solution with a mass fraction of 1% to 8% at room temperature for 20 to 60 minutes, stirring to make the alkali solution fully contact with the small tongcao, washing and drying to obtain the alkali-activated small tongcao.

3. The preparation method according to claim 1 or 2, characterized in that: The alkaline solution soaking step also includes a pretreatment step: ultrasonically washing the raw material of the smilax china with an ethanol aqueous solution, drying it, and cutting it into a preset size.

4. The preparation method according to claim 1 or 2, characterized in that: The mass ratio of the alkali-activated cyperus rotundus, amino acid hydrochloride and catalyst is 10:(3-12):(0.6-2.4).

5. The preparation method according to claim 1 or 2, characterized in that: The mass ratio of the amino-modified cyperus rotundus, the aminopyridine carboxylic acid ligand, and the first metal salt is 10:(0.6-2.5):(2.2-12.5), wherein the first metal salt is a soluble metal salt.

6. The preparation method according to claim 5, characterized in that: The step of in-situ growth of MOFs comprises: first placing the amino-modified smilax glabra in a first metal salt aqueous solution, adding the aminopyridine carboxylic acid ligand, heating and stirring until the aminopyridine carboxylic acid ligand is completely dissolved, transferring to a microwave reactor after cooling to carry out in-situ growth of MOFs at 35-60°C and 80-350W, filtering, washing, and vacuum drying to obtain the MOFs-smilax glabra composite material.

7. The preparation method according to claim 6, characterized in that: The MOFs in-situ growth reaction carried out in the microwave reactor is divided into two stages: the microwave power of the first stage is 80-120 W, and the reaction time is 10-40 min; the microwave power of the second stage is 250-350 W, and the reaction time is 1-5 h.

8. The preparation method according to any one of claims 1, 2 and 6-7, characterized in that: The steps of directional freeze-drying molding include: dissolving polyvinyl pyrrolidone in deionized water to prepare the polyvinyl pyrrolidone solution, adding tetraphenylporphyrin metal salt powder to the polyvinyl pyrrolidone solution, fully stirring and ultrasonicating to make the tetraphenylporphyrin metal salt evenly dispersed in the gel solution to form the mixed gel solution; firstly arranging the MOFs-small tongcao composite material at the bottom of the mold, then adding the mixed gel solution, and then sealing, freeze-molding, and freeze-drying to form aerogel, so as to obtain an aerogel composite purification material with preset specifications.

9. The preparation method according to claim 8, characterized in that: The mass fraction of the polyvinyl pyrrolidone solution is 4% to 20%, and the mass ratio of polyvinyl pyrrolidone to tetraphenylporphyrin metal salt is 9 to 11: 0.19 to 0.

21.

10. The preparation method according to claim 8, characterized in that: The step of forming the mixed gel solution includes: first adding a second metal salt and an amino compound to the polyvinyl pyrrolidone solution and fully dissolving them, then adding the tetraphenylporphyrin metal salt powder, fully stirring and ultrasonically treating to obtain the mixed gel solution; wherein the mass ratio of the polyvinyl pyrrolidone, the second metal salt, the amino compound and the tetraphenylporphyrin metal salt is 9-10.5: 0.8-1.2: 1.8-2.1: 0.19-0.

21.

11. The preparation method according to claim 10, characterized in that: The step of forming the mixed gel solution also includes: adding a fragrance aid to the polyvinyl pyrrolidone solution to make the mixed gel solution have fragrance.

12. An aerogel composite purification material prepared by the preparation method according to any one of claims 1 to 11.

13. Use of the aerogel composite purification material according to claim 12 in purifying air, wherein: The aerogel composite purification material adsorbs at least one of benzene, benzene derivatives, formaldehyde, trichloroethylene, tetrachloroethylene, nitrogen oxides, CO, ammonia and nicotine in air pollutants.

14. The use according to claim 13, characterized in that: At room temperature and pressure, the saturated adsorption amounts of the aerogel composite purification material for benzene, toluene, trichloroethylene, formaldehyde, NO, CO, ammonia and nicotine are 135-550, 100-485, 50-114, 90-245, 35-90, 30-85, 35-96 and 85-255 mg / g, respectively.

15. An air purification filter assembly, characterized in that: The invention comprises the aerogel composite purification material as claimed in claim 13.

16. An air purifier, characterized in that: Includes the air purification filter component described in claim 15.

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