Modified loofah sponge fiber composite material as well as preparation method and application thereof

Abstract

The invention provides a modified loofah sponge fiber composite material as well as a preparation method and application thereof. According to the preparation method, natural loofah sponge is mainly used as a raw material and is sequentially subjected to amino modification, aerogel preparation and fiber membrane composite treatment, so that the aerogel and a spandex fiber membrane are introduced into the loofah sponge, the finally prepared modified loofah sponge fiber composite material has a hierarchical pore structure, and the physical adsorption performance of the loofah sponge fiber composite material on air pollutants is effectively improved; groups such as amino groups are introduced into the loofah sponge, so that the chemical adsorption performance on air pollutants can be improved; the spandex fiber membrane can effectively filter particulate matters such as PM2.5; therefore, the modified loofah sponge fiber composite material has better selective adsorption on aldehydes such as formaldehyde and the like, and meanwhile has better removal capacity on air pollutants such as PM2.5, benzene series, nicotine, NOX, CO, trichloroethylene or tetrachloroethylene and the like, so that the air pollutants in the environment are effectively removed, and therefore, the modified loofah sponge fiber composite material has the advantages of environmental protection, environmental protection and the like. The material can be used as a pollutant purification material in air pollutant adsorption.

Description

Technical Field

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

[0002] In modern life, indoor air pollution has become one of the main environmental problems faced by people. There are various common indoor air pollutants, including benzene series, formaldehyde, nitrogen oxides, carbon monoxide, ammonia, trichloroethylene and tetrachloroethylene, etc. These pollutants are highly toxic and widely exist in furniture and household products such as artificial boards, adhesives, paints, coatings, wallpapers, carpets, and daily chemicals. They will slowly diffuse into the indoor air. People exposed to such a polluted environment for a long time may suffer from respiratory diseases, allergic reactions, cardiovascular diseases and even more serious diseases, posing a serious threat to human health. Therefore, indoor air pollution has attracted extensive attention from all sectors of society.

[0003] Currently, 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, and relatively low cost. The key to 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 sieves, etc. They 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] Patent application for invention CN113813737A discloses an air purification material for removing formaldehyde in indoor air. By weight, it is composed of the following components: 50 - 80 parts of melt - blown polypropylene, 40 - 60 parts of melt - blown polylactic acid and 100 - 180 parts of powdery formaldehyde adsorption material. Among them, the formaldehyde adsorption material, by weight, is composed of 60 - 80 parts of thermosetting resin, 10 - 20 parts of caustic soda, 5 - 6 parts of surfactant, 2 - 5 parts of polyvinylpyrrolidone, 50 - 60 parts of ethanol solvent and 4 - 6 parts of triethylenetetramine. This patent application for invention also correspondingly proposes a preparation method and a device, which can remove minute impurities in the air under ventilation conditions on the basis of removing indoor formaldehyde to meet the actual use requirements.

[0005] Although the above - mentioned patent application for invention discloses that it has a high removal rate for formaldehyde, it does not reflect its specific adsorption effect on indoor air pollutants, and even less involves its adsorption condition for the characteristic flue gas in a smoking room. With the continuous improvement of people's requirements for indoor air quality, the existing 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

[0006] Therefore, the main object of the present invention is to provide a modified loofah fiber composite material, a preparation method and an application thereof in view of the deficiencies of the prior art, which can effectively remove air pollutants in the environment.

[0007] To achieve the above object, the first aspect of the present invention provides a preparation method of a modified loofah fiber composite material, comprising the steps of: Amino modification: First, the loofah is subjected to alkali activation and epoxidation ring-opening treatment in sequence, and then grafting treatment is carried out using an aminobenzoic acid compound to obtain amino-modified loofah; Preparation of aerogel: The amino-modified loofah is immersed in an aqueous solution of polyvinyl alcohol, and freeze-setting drying treatment is carried out to obtain a modified loofah aerogel; Fiber membrane composite: A layer of spandex fiber membrane is formed on the surface of the modified loofah aerogel.

[0008] The second aspect of the present invention provides a modified loofah fiber composite material prepared by the above method, and includes the above modified loofah aerogel and a spandex fiber membrane loaded on the surface of the modified loofah aerogel. Wherein, the spandex fiber membrane can be loaded on one side surface or both side surfaces of the modified loofah aerogel.

[0009] The third aspect of the present invention provides the use of the above modified loofah fiber composite material in adsorbing air pollutants.

[0010] The fourth aspect of the present invention provides an air purification filter element, which includes the above modified loofah fiber composite material.

[0011] The fifth aspect of the present invention provides an air purifier, which includes the above air purification filter element.

[0012] Therefore, the above modified loofah fiber composite material provided by the present invention has a hierarchical pore structure and has good physical adsorption performance for air pollutants; amino groups and other groups are introduced onto the loofah, which can improve the chemical adsorption performance for air pollutants; the spandex fiber membrane can effectively filter particulate matters such as PM2.5; thus, the modified loofah fiber composite material has good selective adsorption for aldehydes such as formaldehyde, and at the same time has good removal ability for air pollutants such as PM2.5, benzene series, nicotine, NO X , CO, trichloroethylene or tetrachloroethylene, etc., and the material has high mechanical properties and strong plasticity, so that it can be processed into various shapes and specifications according to different application scenarios and requirements, providing a certain basis for further application as a filter element material in air purifiers, thereby effectively removing air pollutants in the environment. Description of the Drawings

[0013] Figure 1 This is a photograph of the composite purification material provided in Embodiment 5 of the present invention. Detailed implementation manners

[0014] 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.

[0015] In the ranges disclosed in the present invention, the endpoints and any values of the ranges 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 of each range and individual point values, 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.

[0016] In the present invention, unless otherwise specified and / or described, all numerical values related to the amounts of components are "weight". Unless otherwise specified, the terms used in the present invention are common terms in the art. For the preparation processes, test methods, etc. used in each implementation manner 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.

[0017] The main objective of the present invention is to provide, in view of the deficiencies of the prior art, a modified loofah fiber composite material, its preparation method and application, which can effectively remove air pollutants in the environment.

[0018] To achieve the above objective, in the first aspect of the present invention, a preparation method of a modified loofah fiber composite material is provided. This preparation method mainly uses natural loofah as the raw material, and successively undergoes amino modification, preparation of aerogel, and fiber membrane composite treatment, so that aerogel and spandex fiber membrane are introduced onto the loofah, making the finally prepared modified loofah fiber composite material have a hierarchical pore structure, effectively improving its physical adsorption performance for air pollutants; at the same time, groups such as amino groups are introduced onto the loofah, effectively improving the chemical adsorption performance of the modified loofah fiber composite material for air pollutants, thereby achieving the effective removal of air pollutants in the environment.

[0019] Specifically, a preparation method of a modified loofah fiber composite material includes the steps: Amino modification: First, the loofah is successively subjected to alkali activation and epoxy ring-opening treatment, and then grafted with an aminobenzoic acid compound to obtain amino-modified loofah; Preparation of aerogel: Immerse the amino-modified loofah in an aqueous solution of polyvinyl alcohol and perform freeze-setting drying treatment to obtain a modified loofah aerogel; Fiber membrane composite: Form a layer of spandex fiber membrane on the surface of the modified loofah aerogel.

[0020] In the step of amino modification, the purpose of the alkali activation treatment is mainly to break the intermolecular hydrogen bonds of the loofah fiber, expose more hydroxyl groups on the loofah fiber, thereby increasing the reaction sites, so that the hydroxyl groups that are originally difficult to participate in the reaction can more smoothly combine with the corresponding reactant groups. Specifically, the steps of the alkali activation treatment include: soaking the loofah in a first alkali solution with a mass fraction of 2% - 4% and reacting at 30°C - 50°C for 1 - 3 h to obtain alkalized loofah; wherein, the solid-liquid ratio of the loofah to the first alkali solution is 10 - 20 g / L. The shape of the loofah is not limited and can be specifically determined according to actual needs. In a specific embodiment, the shape of the loofah is a rectangle of 8 - 12 cm × 8 - 12 cm and has a mass of about 1.2 - 3.0 g.

[0021] However, when the concentration of the first alkali is low, or the reaction temperature is low, or the reaction time is short, the structural effect on the loofah is not obvious. When the concentration of the first alkali is too high, or the reaction temperature is too high, or the reaction time is too long, the fiber structure of the loofah will be damaged, a large amount of cellulose will be hydrolyzed, and breakage and fragmentation will occur, resulting in too large pores in the loofah, which is not conducive to intercepting air pollutants. Therefore, the mass fraction of the first alkali solution is preferably 2% - 4%, such as 2%, 2.5%, 3%, 3.5%, 4%, etc.; the reaction temperature is preferably 30°C - 50°C, such as 30°C, 35°C, 40°C, 45°C, 50°C, etc.; the reaction time is preferably 1 - 3 h, such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc. The first alkali solution can be a strong alkaline solution such as sodium hydroxide solution or potassium hydroxide solution. Among them, the first alkali solution is preferably an ethanol / water solution of the alkali, and the volume ratio of ethanol to water in it is 1:3.5 - 4.5; in this way, the ethanol in the first alkali solution can dissolve and remove the foreign substances attached to the surface of the loofah, playing a cleaning role, making the loofah raw material more pure and avoiding the influence of impurities in the subsequent processing; in addition, the loofah may contain some fat-soluble impurities, and the ethanol solution can dissolve and remove part of them during washing, which is more helpful for subsequent modification.

[0022] When the solid-liquid ratio of the loofah to the first alkali solution is relatively small, the reaction efficiency is low. If the reaction time is extended, the time cost is high; when the solid-liquid ratio of the two reaches 20 g / L, the exposed hydroxyl sites on the loofah fiber basically reach equilibrium and it is difficult to increase significantly; therefore, considering comprehensively, the solid-liquid ratio of the loofah to the first alkali solution is preferably 10 - 20 g / L, such as 10 g / L, 12 g / L, 14 g / L, 15 g / L, 16 g / L, 18 g / L, 20 g / L, etc.

[0023] The epoxidation ring-opening treatment is mainly to prepare for the subsequent grafting of aminobenzoic acid compounds onto the alkalized loofah sponge. Specifically, an epoxidizing reagent, the alkalized loofah sponge, and a second alkaline aqueous solution are mixed and reacted at 40 °C to 70 °C for 2 to 6 h to obtain epoxidized loofah sponge. The epoxidizing reagent mainly undergoes a nucleophilic substitution reaction with the hydroxyl hydrogen of cellulose in the loofah sponge under the catalysis of an alkali to obtain a loofah sponge with epoxy groups, preparing for the further grafting of aminobenzoic acid compounds. If the dosage of the epoxidizing reagent is too small and its mass concentration is low, the ring-opening reaction of cellulose in the loofah sponge is restricted, thereby affecting the grafting amount of the epoxidized loofah sponge and aminobenzoic acid compounds and resulting in low grafting efficiency; on the contrary, if its dosage is too high, side reactions may occur, thereby affecting the grafting efficiency. Therefore, the mass ratio of the epoxidizing reagent to the alkalized loofah sponge is preferably 10:1 to 25:1, such as 10:1, 12:1, 15:1, 17:1, 18:1, 20:1, 23:1, 25:1, etc. The epoxidizing reagent is preferably epichlorohydrin. The mass fraction of the second alkaline aqueous solution is preferably 4% to 6%, and the alkali therein can be a strong alkali such as sodium hydroxide or potassium hydroxide.

[0024] The main purpose of the grafting treatment is to simultaneously introduce carboxyl, amino, and benzene ring functional groups onto the epoxidized loofah sponge matrix, increasing the adsorption active sites of the composite material. If the dosage of the aminobenzoic acid compound is too small, it is not conducive to forming sufficient active adsorption sites on the loofah sponge matrix, thereby affecting the removal of air pollutants such as aldehydes (such as formaldehyde), benzene series compounds, and nicotine; however, if the dosage of the aminobenzoic acid compound is too large, the grafting rate of the loofah sponge has reached the maximum value and the reaction efficiency decreases. Therefore, the mass ratio of the aminobenzoic acid compound to the epoxidized loofah sponge is 1:1 to 3:1, such as 1:1, 2:1, 3:1, etc. Among them, the aminobenzoic acid compound includes at least one of p-aminobenzoic acid, 2-aminoterephthalic acid, and 3,5-diaminobenzoic acid. The specific steps of the grafting treatment include: adding the aminobenzoic acid compound and the epoxidized loofah sponge according to a mass ratio of 1:1 to 3:1 into a sodium carbonate aqueous solution with a mass fraction of 0.8% to 1.2% and reacting at 50 °C to 80 °C for 5 to 10 h to obtain the amino-modified loofah sponge.

[0025] Furthermore, before the step of amino modification, there is a pretreatment step: cutting the natural loofah sponge fiber, unfolding it to obtain a loofah sponge fiber with a complete network structure, and then trimming it to a predetermined size, washing, and drying it.

[0026] In the step of preparing the aerogel, if the concentration of the polyvinyl alcohol aqueous solution is too low, the effect on the amino-modified loofah sponge is not obvious, and it is not easy to form a hierarchical pore structure in the aerogel formed after freeze-drying. On the contrary, if the concentration of polyvinyl alcohol is too high, it is too viscous, and the pore structure formed by the aerogel is relatively dense, which is not conducive to the diffusion of air pollutants. Therefore, the mass fraction of the polyvinyl alcohol aqueous solution is preferably 3% to 8%, such as 3%, 4%, 5%, 6%, 7%, 8%, etc. In this way, the polyvinyl alcohol aerogel can further enrich the mesopores and some micron-sized pores of the amino-modified loofah sponge, and can fully expose more active sites. The polyvinyl alcohol in the polyvinyl alcohol aqueous solution is preferably polyvinyl alcohol 0588. Specifically, the step of preparing the aerogel includes: first placing the amino-modified loofah sponge in a mold, then injecting the polyvinyl alcohol aqueous solution into the mold until the amino-modified loofah sponge is completely submerged, freezing and shaping with liquid nitrogen, freeze-drying, and demolding for standby. Among them, the specifications of the mold are determined according to the actual situation. In a specific embodiment, the specifications of the mold are 8 - 12 cm × 8 - 12 cm × 1 - 1.5 cm.

[0027] Furthermore, the polyvinyl alcohol aqueous solution further includes fibers with a diameter of 10 - 70 μm, and the fibers are carboxymethyl microcrystalline cellulose, polyester fiber or a combination of both. The carboxyl functional groups contained in the carboxymethyl cellulose and the phenyl functional groups contained in the polyester fiber provide active adsorption sites for the composite material, which is beneficial to the adsorption of pollutants such as ammonia, nicotine, benzene series substances and trichloroethylene. Therefore, if the doping amount of the fibers is too small, the adsorption sites that can be provided are few; on the contrary, if the doping amount of the fibers is too large, the fibers are prone to agglomeration, which is not conducive to the uniform dispersion of the fibers. Therefore, preferably, the mass fraction of the fibers in the polyvinyl alcohol aqueous solution is 5% - 12%, such as 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, etc. Among them, the carboxymethyl microcrystalline cellulose in the present invention is prepared from microcrystalline cellulose as a raw material.

[0028] In a specific embodiment, the fibers are small-diameter fibers with a diameter of 20 - 30 μm and large-diameter fibers with a diameter of 50 - 60 μm. In this way, the polyvinyl alcohol aqueous solution can effectively fix the fibers on the amino loofah sponge. The fibers with different diameters are doped into the aerogel interior, increasing the specific surface area and porosity, and improving the mechanical properties of the aerogel. Preferably, the mass ratio of the small-diameter fibers to the large-diameter fibers in the polyvinyl alcohol aqueous solution is 0.5:1 - 2.5:1, such as 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, etc.

[0029] In another specific embodiment, the small-diameter fiber is carboxymethyl microcrystalline cellulose, and the large-diameter fiber is polyester fiber, that is, the aqueous polyvinyl alcohol solution further includes carboxymethyl microcrystalline cellulose with a diameter of 20 - 30 μm and polyester fiber with a diameter of 50 - 60 μm uniformly dispersed therein, and the mass ratio of carboxymethyl microcrystalline cellulose to polyester fiber therein is 0.5:1 - 2:1.

[0030] The steps of fiber membrane composite include: using the spandex fiber solution as a raw material, and forming the spandex fiber membrane on the surface of the modified loofah sponge aerogel by electrospinning. Among them, the spandex fiber membrane can be loaded on one-sided surface or both surfaces of the modified loofah sponge aerogel.

[0031] The spandex fiber has hydrophobicity, and has a relatively high specific surface area, uniform mesopore distribution, and high porosity, which is beneficial to the diffusion and transmission of pollutants in the fiber and has strong physical adsorption. If the concentration of the spandex fiber solution is too high, the fibers may adhere to and stack on each other, resulting in over-dense and unevenly distributed pores, making it difficult for air pollutants to fully enter the interior of the fibers, reducing the effective adsorption area, and being not conducive to the adsorption of small molecules or particles; however, if the concentration of the spandex fiber is too low, phenomena such as discontinuous spinning fibers and broken filaments will occur. Therefore, the mass fraction of the spandex fiber solution is 20% - 26%, such as 20%, 21%, 22%, 23%, 24%, 25%, 26%, etc. In a specific embodiment, the spandex fiber solution is polyurethane 1085A solution, and its solvent is composed of DMF (N,N-dimethylformamide) and THF (tetrahydrofuran) with a volume ratio of 0.8 - 1.2:0.8 - 1.2.

[0032] Furthermore, the spandex fiber solution further includes an adsorption site supply agent uniformly dispersed therein, and the mass ratio of the adsorption site supply agent to the spandex fiber therein is 1 - 2:9 - 11, and the adsorption site supply agent is a phenylsilane compound, a metal salt, or any combination of the two.

[0033] The phenylsilane compound has a large conjugated system and certain hydrophobicity. If the dosage of the phenylsilane compound is too small, the number of sites capable of generating π-π interaction or providing hydrophobic interaction with pollutants such as nicotine, 3-vinylpyridine, and benzene series compounds is limited; however, if the dosage of the phenylsilane compound is too large, it may affect the fiber formation and mechanical properties. Therefore, the mass ratio of the phenylsilane compound to the spandex fiber in the spandex fiber solution is 1:8 - 12. The phenylsilane compound can be phenylsilane, diphenylsilane, triphenylsilane, etc.

[0034] The metal salt can be a soluble transition metal salt, such as ferrous sulfate, nickel nitrate, and cobalt sulfate, etc., where the Fe 2+ 、Co2+ and Ni 2+ Transition metal ions such as are uniformly loaded on the spandex fiber and can form complexes with CO etc. If the dosage of the metal salt is too small, few adsorption sites are provided and it is difficult to play a role. However, if the dosage of the metal salt is too large, it may affect fiber formation and mechanical properties. Therefore, the mass ratio of the metal salt to the spandex fiber in the spandex fiber solution is 1:8 - 12.

[0035] Furthermore, the spandex fiber solution further includes a fragrance component uniformly dispersed therein, and the mass ratio of the fragrance component to the spandex fiber is 1:18 - 22. The fragrance component can be benzoin essential oil, agarwood essential oil, clove essential oil, vetiver essential oil, sandalwood essential oil, etc. It can not only be used as a fragrance enhancer, but also has a certain antibacterial effect.

[0036] The second aspect of the present invention provides a modified loofah fiber composite material prepared by the above method, and includes the above-mentioned modified loofah aerogel and a spandex fiber membrane loaded on the surface of the modified loofah aerogel. Among them, the spandex fiber membrane can be loaded on one-sided or both-sided surfaces of the modified loofah aerogel.

[0037] The third aspect of the present invention provides an application of the above-mentioned modified loofah fiber composite material in adsorbing air pollutants. Among them, the modified loofah fiber composite material, as an air pollutant purification material, can adsorb components such as aldehydes such as formaldehyde, benzene series, nicotine, NO X , CO, trichloroethylene, tetrachloroethylene, and PM2.5 in environmental pollutants. The multi-sized microfibers combine the high interception efficiency of smaller-diameter fibers and the structural stability of larger-diameter fibers, greatly improving the adsorption efficiency and purification effect.

[0038] The main reasons why the modified loofah fiber composite material can be used as an air pollutant purification material are as follows: (1) Physical adsorption: The modified loofah sponge has a large pore structure and high porosity, which is conducive to the diffusion and transmission of pollutant molecules. The modified loofah sponge fibers with a larger diameter are used as the skeleton material, and the carboxymethyl microcrystalline fibers and polyester fibers with a smaller diameter are compounded with the loofah sponge fibers with a larger diameter through polyvinyl alcohol aerogel, forming a branched structure similar to tree branches on the surface of the modified loofah sponge fibers, making the internal pore structure of the composite material more complex and tortuous, increasing the specific surface area and porosity of the fibers, and improving the interception efficiency of air pollutants. The polyvinyl alcohol aerogel further endows the purification material with abundant mesopores and some micron-sized pores, which can fully expose more active sites. The electrospun spandex fibers have a uniform mesoporous network structure with small pore diameters and high porosity, providing more active sites, which is conducive to the diffusion and transmission of pollutants inside the fibers and has strong physical adsorption. In addition, the electrospun fibers also have certain surface charge characteristics, which can enhance the adsorption capacity for pollutants through electrostatic interaction. (2) Chemical adsorption: The modified loofah sponge simultaneously introduces carboxyl, amino, and benzene ring functional groups. The amino group can undergo a condensation reaction with aldehyde pollutants such as formaldehyde to form a stable imine or Schiff base structure. There is a strong π-π interaction between the benzene ring group and benzene series molecules. The carboxyl group can undergo acid-base interaction with NH 3 , nicotine, 3-vinylpyridine, etc. At the same time, the amino and carboxyl functional groups in the composite material provide a large number of hydrogen bond interaction sites. A certain amount of triphenylsilane is doped in the spandex fibers, making the surface of the composite material have certain hydrophobicity. At the same time, triphenylsilane has a large conjugated system, and the phenyl functional group in it has π-π interaction with pollutants such as nicotine, benzene series, and trichloroethylene. The metal cations loaded on the spandex fibers may form complexes with CO, nicotine, etc. (3) The electrospun spandex fiber membrane on the surface of the purification material can effectively filter particulate matter such as PM2.5. The electrospun fibers also have certain hydrophobicity, endowing the material with certain adsorption performance and stability. Further adding fragrance components makes the material have certain fragrance-releasing and antibacterial functions.

[0039] At normal temperature and pressure, the saturated adsorption capacities of the modified loofah sponge fiber composite material for formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene are 70 - 190 mg / g, 240 - 595 mg / g, 160 - 475 mg / g, 95 - 315 mg / g, 20 - 85 mg / g, 30 - 80 mg / g, 65 - 185 mg / g, and 50 - 125 mg / g respectively, and the filtration efficiency for PM2.5 particles is 89.0% - 99.9%.

[0040] The fourth aspect of the present invention provides an air purification and filtration component, including the above-mentioned modified loofah fiber composite material. Among them, the filtration component is a filter element or a filter screen, etc. That is, the modified loofah fiber composite material can be combined into a purification filter element or a filter screen and other filtration components, and can also be used in combination with other filtration components in an air purifier.

[0041] The fifth aspect of the present invention provides an air purifier, including the above-mentioned air purification and filtration component.

[0042] Therefore, the above-mentioned modified loofah fiber composite material provided by the present invention has good selective adsorption for aldehydes such as formaldehyde, and at the same time has good removal ability for air pollutants such as PM2.5, benzene series, nicotine, NO X , CO, trichloroethylene or tetrachloroethylene, etc. Moreover, the material has high mechanical properties and strong plasticity, enabling it to be processed into various shapes and specifications according to different application scenarios and requirements, providing a certain basis for further application as a filter element material in an air purifier.

[0043] The technical solutions of the present invention will be further described in detail below through specific embodiments.

[0044] Examples 1-9 Each of Examples 1-9 of the present invention provides a preparation method of a modified loofah fiber composite material, including the following steps: (1) Pretreatment Select mature, dry, and pest-free loofah. Cut off the two ends of the loofah fiber, cut it longitudinally and remove the fiber in the central part, unfold it to obtain a loofah fiber with a complete network structure, and then cut it into a size of 10 cm × 10 cm. The mass of each block of loofah is about 2 g. Wash it clean with deionized water, wash it with ethanol, and dry it in a vacuum at 60 °C to control the moisture content at about 5%.

[0045] (2) Amino modification Weigh 40 g of pretreated loofah. According to a solid-liquid ratio of 15 g / L, soak the loofah in 2.7 L of 3% NaOH alcohol / water (1 / 4) at 40 °C and stir for 2 h. Wash it with water until neutral, wash it with absolute ethanol, and dry it to obtain alkalized loofah.

[0046] Epoxidation ring-opening reaction: For the alkalized loofah, according to a solid-liquid ratio of 1:50 g / mL, add the alkalized loofah to 5% NaOH aqueous solution, add epichlorohydrin, and react at 60 °C for 5 h. Wash it with water until neutral, wash it with absolute ethanol, and dry it to obtain epoxidized loofah.

[0047] Prepare modified loofah: Add the above epoxidized loofah to 100 mL of 1% Na2 CO 3 In an aqueous solution, 3,5-diaminobenzoic acid was then added, and the reaction was carried out at 70 °C for 8 h. After suction filtration, washing with water, washing with ethanol, and vacuum drying, amino-modified loofah sponge was obtained.

[0048] (3)Preparation of aerogel The amino-modified loofah sponge obtained in step (2) was placed in a mold. Polyvinyl alcohol 0588 was weighed and slowly added to water, and mechanically stirred until completely dissolved; then carboxymethyl microcrystalline cellulose and polyester fiber were weighed and dispersed into the above polyvinyl alcohol aqueous solution respectively, and mechanically stirred to make them evenly dispersed. After ultrasonic degassing, it was slowly injected into a 10 cm×10 cm×1.2 cm cuboid mold containing modified loofah sponge until it was just completely immersed. It was frozen and fixed with liquid nitrogen, and then freeze-dried and demolded to obtain modified loofah sponge aerogel, which was prepared for the next electrospinning.

[0049] (4)Fiber membrane composite Polyurethane 1085A, triphenylsilane and cobalt sulfate heptahydrate were weighed and slowly added to a DMF / THF mixed solution (volume ratio of the two is 1:1), and stirred at 70 °C for 2 h until completely dissolved. Then benzoin essential oil was added and mechanically stirred to dissolve, and ultrasonic degassing was carried out. Then the modified loofah sponge aerogel obtained in step (3) was adhered to the receiving plate of electrospinning, and a layer of spandex fiber membrane was formed on the single-side surface of the modified loofah sponge aerogel, and vacuum dried to obtain a modified loofah sponge fiber membrane composite material. Among them, the electrospinning preparation conditions were as follows: a spinning syringe with a specification of 5 mL was used, a 21-gauge needle was selected, the spinning temperature was 25 °C, the spinning distance was 15 cm, the advancing rate of the spinning syringe was 0.5 mL / h, and the spinning voltage was 20 KV.

[0050] Among them, the material dosages in each example are shown in Table 1: Table 1 Material dosages in examples (unit: g)

[0051] Example 10 This example provides a modified loofah sponge fiber composite material, which is Figure 1 basically the same as the preparation method of the modified loofah sponge fiber composite material provided in Example 5 shown. The main differences are as follows: in this example, 2-aminoterephthalic acid was used instead of 3,5-diaminobenzoic acid in the corresponding step of Example 5 in step (2); in step (4), phenylsilane was used instead of triphenylsilane in the corresponding step of Example 5, and ferrous sulfate was used instead of cobalt sulfate heptahydrate in the corresponding step of Example 5; other conditions were the same as those in Example 5.

[0052] Example 11 This embodiment provides a modified loofah fiber composite material, which has basically the same preparation method as the modified loofah fiber composite material provided in Embodiment 6. The main difference is that: in step (4) of this embodiment, cobalt sulfate heptahydrate in the corresponding step of Embodiment 6 is omitted; other conditions are the same as those in Embodiment 6.

[0053] Embodiment 12 This embodiment provides a modified loofah fiber composite material, which has basically the same preparation method as the modified loofah fiber composite material provided in Embodiment 5. The main difference is that: in this embodiment, in step (4), a layer of spandex fiber film is formed on each of the two side surfaces of the modified loofah aerogel.

[0054] Comparative Example Each of Comparative Examples 1-3 provides a modified loofah fiber composite material, and its preparation method is basically the same as that of Embodiment 1 or 4 or 7. The main differences are as follows: Comparative Example 1: Adjust the dosage of 3,5-diaminobenzoic acid in step 2 of Embodiment 1 to 1.8 g, and other conditions are the same as those in Embodiment 1; Comparative Example 2: Adjust the dosage of polyurethane in step 4 of Embodiment 1 to 0.072 g, and then adjust the dosages of triphenylsilane, cobalt sulfate heptahydrate and benzoin to 0.0072 g, 0.0072 g and 0.0036 g respectively, and other conditions are the same as those in Embodiment 1; Comparative Example 3: Omit the electrospun fibers in Embodiment 7, and other conditions are the same as those in Embodiment 7.

[0055] Verification of Adsorption Performance This embodiment provides the application of the modified loofah fiber composite materials provided in the above Embodiments 1-12 and Comparative Examples 1-3 in the preparation of air pollutant purification materials respectively. In this experiment, by using a multi-component adsorption breakthrough curve analyzer, the adsorption performances of 15 materials prepared in Embodiments 1-12 and Comparative Examples 1-3 for formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene were evaluated. At the same time, the filtration performance of the purification materials for PM2.5 particulate matter was evaluated with reference to a well-known method (Structural Regulation and Performance Research of Electrospun High-Efficiency Low-Resistance Functionalized PM2.5 Filter Membrane, Ph.D. Thesis, South China University of Technology, 2020). The filtration performance of the above 15 materials for PM2.5 particulate matter was evaluated by simulating a haze environment in the laboratory to prove that the modified loofah fiber composite material provided in the embodiments of the present invention can be used as an air pollutant purification material and can effectively remove indoor air pollutants. The specific method is as follows: Air pollutant evaluation experiment: Weigh about 0.2 g of the modified loofah fiber composite material sample and fill it into a sample tube with an inner diameter of 10 mm. Activate it by purging with nitrogen at 50 °C for 120 min, and the purging gas flow rate is 20 sccm. The experimental conditions are set at normal temperature and pressure. The target adsorption pollutant concentration is set at 5000 ppm, the total inlet gas flow rate is 80 mL / min, and nitrogen is used as the carrier gas and does not participate in adsorption.

[0056] Nicotine evaluation experiment: Weigh about 0.2 g of the modified loofah fiber composite material sample and fill it into a sample tube with an inner diameter of 10 mm. Activate it by purging with nitrogen at 50 °C for 120 min, and the purging gas flow rate is 20 sccm. The experimental conditions are set at normal temperature and pressure. The target adsorption pollutant concentration is set at 55 ppm, the total inlet gas flow rate is 80 mL / min, and nitrogen is used as the carrier gas and does not participate in adsorption.

[0057] PM2.5 particulate matter evaluation experiment: Cut the modified loofah fiber composite material into a circular filter membrane with a diameter of 10 cm, and use flanges to fix both sides of the modified loofah fiber composite material to ensure airtightness. Use sandalwood combustion smoke as a real aerosol mimic, keep the PM2.5 index at about 300, the face wind speed is 5.33 cm / s, and ordinary indoor air is used as the carrier and does not participate in adsorption. Calculate the filtration efficiency (η, unit: %) of the composite material for PM2.5 particulate matter.

[0058] Table 2 Evaluation results of the purification ability of the modified loofah fiber composite material for air pollutants Pollutant evaluation Formaldehyde saturated adsorption capacity (mg / g) Benzene saturated adsorption capacity (mg / g) Toluene saturated adsorption capacity (mg / g) Nicotine saturated adsorption capacity (mg / g) CO saturated adsorption capacity (mg / g) NO saturated adsorption capacity (mg / g) <![CDATA[NH 3 Saturated adsorption capacity (mg / g)]]> Trichloroethylene saturated adsorption capacity (mg / g) Filtration efficiency of PM2.5 % Example 1 71 242 167 98 23 31 65 53 89.0% Example 2 93 307 203 114 36 47 87 71 93.0% Example 3 122 389 271 171 43 54 105 90 95.0% Example 4 152 518 399 265 57 67 162 112 99.9% Example 5 178 563 435 295 54 69 155 115 99.7% Example 6 165 523 412 271 55 68 151 111 99.2% Example 7 140 489 373 228 50 57 147 102 98.0% Example 8 143 338 258 142 41 55 107 82 99.5% Example 9 154 392 317 156 37 42 113 87 91.0% Example 10 105 488 396 223 45 55 134 85 99.3% Example 11 162 519 410 249 10 15 37 87 98.7% Example 12 189 594 471 311 81 79 183 121 99.9% Comparative Example 1 55 197 104 71 21 29 60 42 87.9% Comparative Example 2 66 214 131 75 12 17 45 47 75.0% Comparative Example 3 129 315 223 158 5 8 32 70 71.0% As can be seen from Table 2: The saturated adsorption amounts of the above-mentioned modified loofah fiber composite materials provided in the above examples for formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene at normal temperature and pressure are 71 - 189 mg / g, 242 - 594 mg / g, 167 - 471 mg / g, 98 - 311 mg / g, 23 - 81 mg / g, 31 - 79 mg / g, 65 - 183 mg / g, and 53 - 121 mg / g respectively, and the filtration efficiency for PM2.5 particles is 89.0% - 99.9%. There are significant differences in the saturated adsorption amounts of the purification materials prepared in different examples for air pollutants. The main reason for this is the differences in their physical and chemical structures.

[0059] The modified loofah fiber composite material provided in Example 8 for formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3The saturated adsorption capacities for formaldehyde, benzene, toluene, nicotine, CO, NO, NH, and trichloroethylene are 143 mg / g, 338 mg / g, 258 mg / g, 142 mg / g, 41 mg / g, 55 mg / g, 107 mg / g, and 82 mg / g respectively, which are significantly lower than those in Example 4. This is mainly because the dosages of carboxymethyl microcrystalline cellulose and polyester fiber in Example 8 are higher than those in Example 4, which may lead to a smaller pore size and a denser pore structure of the composite material, being unfavorable for the diffusion of pollutants and resulting in a decrease in the saturated adsorption capacities of the material for formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene.

[0060] The saturated adsorption capacities of the modified loofah fiber composite material provided in Example 9 for formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene are 154 mg / g, 392 mg / g, 317 mg / g, 156 mg / g, 37 mg / g, 42 mg / g, 113 mg / g, and 87 mg / g respectively, and the filtration efficiency for PM2.5 particulate matter is 91%, which is significantly lower than that in Example 5. This is mainly because there is no carboxymethyl microcrystalline cellulose incorporated, leading to too large pores and a reduced specific surface area of the purification material, resulting in too fast diffusion of pollutants and being unfavorable for the interception and adsorption of pollutants, causing a decrease in the saturated adsorption capacities of formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene, and a decrease in the filtration efficiency for PM2.5 particulate matter.

[0061] The saturated adsorption capacities of the modified loofah fiber composite material provided in Comparative Example 1 for formaldehyde, benzene, toluene, nicotine, and trichloroethylene are 55 mg / g, 197 mg / g, 104 mg / g, 71 mg / g, and 42 mg / g respectively, which are significantly lower than those in Example 1. This is mainly because the dosage of 3,5-diaminobenzoic acid in Comparative Example 1 is lower than that in Example 1, which may affect the condensation reaction between amino groups and formaldehyde, as well as the π-π conjugation between phenyl functional groups and benzene, toluene, and nicotine, resulting in a decrease in the saturated adsorption capacities of the material for substances such as formaldehyde, benzene, toluene, and nicotine.

[0062] The saturated adsorption capacities of the modified loofah fiber composite material provided in Comparative Example 2 for formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3The saturated adsorption capacities for formaldehyde, benzene, toluene, nicotine, CO, NO, NH, and trichloroethylene are 66 mg / g, 214 mg / g, 131 mg / g, 75 mg / g, 12 mg / g, 17 mg / g, 45 mg / g, and 47 mg / g respectively, and the filtration efficiency for PM2.5 particulate matter is 80%, which is significantly lower than that of Example 1. This is mainly because the amount of polyurethane used is lower than that in Example 1, and at the same time, the incorporation amounts of triphenylsilane and cobalt sulfate heptahydrate are lower than those in Example 1. Polyurethane serves as the electrospun fiber framework, and insufficient amount leads to larger pores in the material and reduced physical adsorption performance. The low amount of triphenylsilane may affect the hydrophobicity and the conjugation of phenyl functional groups with benzene, toluene, nicotine, and trichloroethylene. The low amount of cobalt sulfate heptahydrate may affect the complexation of cobalt ions with CO, NO, etc. The combination of these factors results in a decrease in both the physical and chemical adsorption performances of the purification material, causing a decrease in the saturated adsorption amounts of formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene, and at the same time, a significant decrease in the filtration efficiency for PM2.5 particulate matter.

[0063] The modified loofah fiber composite material provided in Comparative Example 3 has saturated adsorption capacities for formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene of 129 mg / g, 315 mg / g, 223 mg / g, 158 mg / g, 5 mg / g, 8 mg / g, 32 mg / g, and 70 mg / g respectively, and the filtration efficiency for PM2.5 particulate matter is 71%, which is significantly lower than that of Example 7. This is mainly because there is no electrospun fiber, resulting in changes in the pore structure of the purification material and a decrease in specific surface area, affecting the interception and adsorption of pollutant molecules and particulate matter, and the absence of triphenylsilane and metal ions. The combination of these factors causes a decrease in both the physical and chemical adsorption performances of the modified loofah fiber composite material, resulting in a decrease in the saturated adsorption amounts of formaldehyde, benzene, toluene, nicotine, CO, NO, NH 3 and trichloroethylene and other substances, and at the same time, a significant decrease in the filtration efficiency for PM2.5 particulate matter.

[0064] Example 13 This example provides an air purification filter element, which is mainly composed of the modified loofah fiber composite material provided in Example 5. In other examples, the air purification filter element can also be composed of the modified loofah fiber composite material provided in any one of Examples 1-4 and 6-12.

[0065] This example also provides an air purification system, including the above air purification filter element.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended 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 perform equivalent replacements on 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 a modified loofah fiber composite material, comprising the steps of: Amino modification: firstly, the loofah is subjected to alkali activation and epoxidation ring-opening treatment in sequence, and then an aminobenzoic acid compound is used for grafting treatment to obtain amino-modified loofah; Preparation of aerogel: immersing the amino-modified loofah in a polyvinyl alcohol aqueous solution and performing freeze-setting and drying treatment to obtain a modified loofah aerogel; Fiber membrane composite: a layer of spandex fiber membrane is formed on the surface of the modified loofah aerogel.

2. The preparation method according to claim 1, characterized in that The alkali activation treatment comprises: soaking the loofah in a first alkali solution with a mass fraction of 2% to 4%, reacting at 30° C. to 50° C. for 1 to 3 hours to obtain an alkalized loofah; wherein the solid-to-liquid ratio of the loofah to the first alkali solution is 10 to 20 g / L.

3. The preparation method according to claim 2, characterized in that The epoxidation ring-opening treatment comprises: mixing the alkalized loofah, an epoxidation agent and a second alkali aqueous solution, and reacting them at 40° C. to 70° C. for 2 to 6 hours to obtain an epoxidized loofah.

4. The preparation method according to claim 3, characterized in that The grafting treatment step includes: adding the aminobenzoic acid compound and the epoxidized loofah in a mass ratio of 1:1 to 3:1 to a sodium carbonate aqueous solution with a mass fraction of 0.8 to 1.2%, and reacting at 50° C. to 80° C. for 5 to 10 hours to obtain amino-modified loofah.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The steps of preparing the aerogel include: firstly placing the amino-modified loofah in a mold, then injecting a polyvinyl alcohol aqueous solution into the mold until the amino-modified loofah is completely submerged, freezing with liquid nitrogen to set the shape, freeze drying, and demolding; the mass fraction of the polyvinyl alcohol aqueous solution is 3% to 8%.

6. The preparation method according to claim 5, characterized in that The polyvinyl alcohol aqueous solution also includes fibers with a diameter of 10 to 70 μm uniformly dispersed therein, and the fibers are carboxymethyl microcrystalline cellulose, polyester fibers, or a combination of the two.

7. The preparation method according to claim 6, characterized in that: The fibers include small-diameter fibers with a diameter of 20 to 30 μm and large-diameter fibers with a diameter of 50 to 60 μm, and the mass ratio of the small-diameter fibers to the large-diameter fibers is 0.5:1 to 2.5:

1.

8. The preparation method according to claim 5, characterized in that: The fiber membrane composite step includes: using spandex fiber solution as raw material, forming the spandex fiber membrane on the surface of the modified loofah aerogel by electrospinning, and the mass fraction of the spandex fiber solution is 20% to 26%.

9. The preparation method according to claim 8, characterized in that The spandex fiber solution also includes an adsorption site provider uniformly dispersed therein, and the mass ratio of the adsorption site provider to the spandex fiber is 1-2:9-11, and the adsorption site provider is a phenylsilane compound, a metal salt or any combination of the two.

10. The preparation method according to claim 9, characterized in that The spandex fiber solution also includes an adsorption site provider uniformly dispersed therein, and the mass ratio of the adsorption site provider to the spandex fiber is 1-2:9-11, and the adsorption site provider is a phenylsilane compound, a metal salt or any combination of the two.

11. The preparation method according to claim 10, characterized in that The mass ratio of the phenylsilane compound to the spandex fiber in the spandex fiber solution is 1:8-12, and the phenylsilane compound is phenylsilane, diphenylsilane or triphenylsilane.

12. The preparation method according to claim 10 or 11, characterized in that: The mass ratio of the metal salt to the spandex fiber in the spandex fiber solution is 1:8-12.

13. The preparation method according to claim 10, characterized in that The spandex fiber solution also includes a fragrance component uniformly dispersed therein, and the mass ratio of the fragrance component to the spandex fiber is 1:18-22.

14. A modified loofah fiber composite material prepared by the preparation method according to any one of claims 1 to 13, characterized in that: The invention comprises the modified loofah aerogel and a spandex fiber membrane loaded on the surface of the modified loofah aerogel.

15. Use of the modified loofah fiber composite material according to claim 14 in adsorbing air pollutants.

16. The use according to claim 15, characterized in that At room temperature and pressure, the saturated adsorption amounts of the modified loofah fiber composite material for formaldehyde, benzene, toluene, nicotine, CO, NO, NH3 and trichloroethylene are 70-190 mg / g, 240-595 mg / g, 160-475 mg / g, 95-315 mg / g, 20-85 mg / g, 30-80 mg / g, 65-185 mg / g and 50-125 mg / g, respectively, and the filtration efficiency for PM2.5 particles is 89.0%-99.9%.

17. An air purification filter assembly, characterized in that: The modified loofah fiber composite material comprises the modified loofah fiber composite material according to claim 14.

18. An air purifier, characterized in that: Includes the air purification filter component described in claim 17.

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