Paper-based air filtering material using gel to load nano functional substance as well as preparation method and application of paper-based air filtering material

Abstract

The invention belongs to the technical field of personal protection air filtering materials, and discloses a paper-based air filtering material for loading a nano functional substance by using gel as well as a preparation method and application of the paper-based air filtering material. According to the material, natural polymer hydrogel is used as a carrier, metal oxide nanoparticles and a metal organic framework compound are loaded at the same time, and efficient compounding with a paper-based material is achieved. The metal oxide is ZnO nanoparticles, the MOFs is ZIF-8, and the natural polymer is carboxymethyl cellulose. The preparation method comprises the following steps: respectively preparing ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles, then mixing the ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles with paper pulp, carrying out papermaking forming, and carrying out freeze drying to obtain the composite paper. Functional substances are effectively prevented from being lost through the gel carrier, uniform distribution and stable combination of the functional substances in the paper base are promoted, and the high PM2.5 filtering paper has high PM2.5 filtering efficiency, excellent antibacterial performance and good biological safety and is suitable for degradable personal protection articles.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of personal protection air filtration materials, and particularly relates to a paper-based air filtration material loaded with nanometer functional substances by using a gel and a preparation method and application thereof. BACKGROUND

[0002] As a personal protection product capable of blocking dust, droplets, saliva, viruses and other substances, a mask can filter air pathogens such as novel coronavirus and influenza A virus, as well as air pollutants such as particulate matter (PM 2.5 ) that are harmful to human bodies. Wearing a mask is a very economical and effective personal protection method. At present, masks have become an important personal protection equipment in daily life and a large consumption product. The base material of the commercially available mask is mainly a non-degradable polymer material such as polypropylene, which is difficult to degrade naturally after being discarded, and brings great pressure and potential harm to the ecological environment. Therefore, it is of great significance to develop green and naturally degradable air filtration materials.

[0003] Paper-based materials mainly use wood fibers as the main raw material and have the advantage of being naturally degradable. However, the current paper-based mask cannot meet the personal protection requirements, for example, the paper-based mask has a low filtration efficiency for submicron particles that seriously harm human health, and does not have the function of inhibiting and inactivating pathogens such as bacteria and viruses in the air. SUMMARY

[0004] The purpose of the present application is to provide a paper-based air filtration material loaded with nanometer functional substances by using a gel and a preparation method and application thereof, which solves the problems of low filtration efficiency of the paper-based mask and the lack of the function of inhibiting and inactivating pathogens such as bacteria and viruses in the air.

[0005] The present application is realized by the following technical solutions: The present application discloses a paper-based air filtration material loaded with nanometer functional substances by using a gel, which is characterized in that a natural polymer hydrogel is used to load nanometer functional substances to realize the compounding with a paper-based material. The nanometer functional substances include metal oxide nanoparticles and metal organic framework compounds; the metal oxide nanoparticles are ZnO nanoparticles; and the metal organic framework compound is ZIF-8, which is synthesized in situ.

[0006] Further, the natural polymer used in the hydrogel is carboxymethyl cellulose.

[0007] The present application further discloses a preparation method of the paper-based air filtration material loaded with nanometer functional substances by using a gel, which comprises the following processes: Preparation of ZIF-8 / carboxymethyl cellulose composite gel particles: sodium carboxymethyl cellulose powder is dissolved in deionized water to form a solution; a Zn salt is added to the solution, and stirred thoroughly until completely dissolved; under stirring, an acidic solution is added dropwise to the solution until the carboxymethyl cellulose forms gel particles, obtaining a carboxymethyl cellulose hydrogel containing Zn 2+ ; The carboxymethyl cellulose hydrogel containing Zn 2+ is added to an aqueous 2-methylimidazole solution to obtain a suspension; The suspension is subjected to a hydrothermal reaction to generate ZIF-8 / carboxymethyl cellulose composite gel particles; Preparation of ZnO / carboxymethyl cellulose composite gel particles: sodium carboxymethyl cellulose powder is dissolved in deionized water to form a solution; ZnO nanoparticles are added and dispersed with ultrasonic assistance to obtain a suspension; Under stirring, an acidic solution is added to the suspension to generate ZnO / carboxymethyl cellulose composite gel particles; Papermaking and forming: The defibrated softwood pulp is mixed uniformly with the ZIF-8 / carboxymethyl cellulose composite gel particles and the ZnO / carboxymethyl cellulose composite gel particles, and a wet paper web with a target basis weight of 20-30 g / m 2 is made by papermaking; the wet paper web is then subjected to simultaneous freeze-drying to finally obtain a paper-based air filtration material.

[0008] Further, in the preparation of the ZIF-8 / carboxymethyl cellulose composite gel particles and the preparation of the ZnO / carboxymethyl cellulose composite gel particles, the carboxymethyl cellulose accounts for 0.05%-0.09% of the total mass of the solution.

[0009] Further, in the ZIF-8 / carboxymethyl cellulose composite gel particles, the mass ratio of ZIF-8 to carboxymethyl cellulose is 0.5:1-5:1, and the particle size is 20-50 μm.

[0010] Further, in the ZnO / carboxymethyl cellulose composite gel particles, the mass ratio of nano-ZnO to carboxymethyl cellulose is 0.1:1-8:1, and the particle size is 20-50 μm.

[0011] Further, in the papermaking and forming, the mass ratio of the ZIF-8 / carboxymethyl cellulose composite gel particles to the ZnO / carboxymethyl cellulose composite gel particles is 5:1-1:5.

[0012] Further, in the papermaking and forming, the total mass of the ZIF-8 / carboxymethyl cellulose composite gel particles and the ZnO / carboxymethyl cellulose composite gel particles to the mass of the softwood pulp is 1:10-4:10.

[0013] Furthermore, the process conditions for simultaneous freeze drying are: drying temperature -70 ~ -50 ℃, vacuum degree 5 ~ 20 Pa, and drying time 4 ~ 12 h.

[0014] The present invention also discloses the application of the paper-based air filter material using gel-loaded nanofunctional materials in the preparation of face masks.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a paper-based air filter material utilizing gel-loaded nanofunctional materials. Compared to existing paper-based mask materials, this invention uses carboxymethyl cellulose gel as a carrier, introducing ZIF-8 with photocatalytic antibacterial and filtering properties, and simultaneously introducing zinc oxide nanoparticles with strong virus inactivation capabilities. This results in a paper-based filter material with better submicron particle filtration performance and antipathogenic properties. The zinc-based MOF and nano-ZnO exhibit excellent band matching and interfacial compatibility due to their shared metal centers, promoting the migration and separation of photogenerated electrons and significantly improving the efficiency of photocatalytic generation of reactive oxygen species. The porous zinc-based MOF acts as a "nanocontainer," efficiently adsorbing and concentrating pathogens and pollutants in the air, providing a high-concentration reaction microenvironment for nano-ZnO. This invention uses a green, biodegradable paper-based material as the substrate, making it more environmentally friendly than currently available personal protective mask materials such as polypropylene.

[0016] The two functional substances, loaded onto a gel, can directly participate in the papermaking process, avoiding loss, mutual interference, and changes in chemical structure; furthermore, the loss rate of functional substances during paper-based material preparation is lower. In the final material, carboxymethyl cellulose and cellulose fibers have structural similarities, which can serve as a bridge between the functional substances and the fibers, making the functional substances and paper-based materials more tightly bonded.

[0017] This invention provides a method for preparing paper-based air filter materials using gel-loaded nanofunctional substances. The method selects the metal-organic framework compound ZIF-8 and zinc oxide nanoparticles as functional substances, and biodegradable carboxymethyl cellulose gel as a carrier. The synthesis of functional substances is combined with the gelation of natural polymers for in-situ loading, and the loaded gel particles are further integrated into the papermaking process. Carboxymethyl cellulose is a modified derivative of natural cellulose, obtained by etherification of natural cellulose, retaining the biodegradability and biocompatibility of natural polymers. The coordination between carboxymethyl cellulose gel and metal ions lays the foundation for the uniform distribution, stable binding, and ultra-efficient utilization of functional substances. The carboxymethyl cellulose gel carrier acts as a protective barrier for the functional substances and a bridge for binding with cellulose in the paper matrix. The relatively independent loading mode also allows for the simultaneous loading and synergistic effect of the two functional substances. Through the above comprehensive effects, the paper-based composite material is ultimately endowed with ideal filtration and protection performance. The preparation process of this invention has good compatibility with existing papermaking processes, and the functional substances have a high retention rate, enabling efficient utilization of the functional substances. Attached Figure Description

[0018] Figure 1 These are scanning electron microscope images of the surface and cross-sectional microstructure of the functional composite paper prepared according to Example 1 of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0020] The detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on these embodiments without inventive effort are within the scope of protection of the present invention.

[0021] By incorporating nanoscale functional materials such as metal-organic frameworks (MOFs) and nano-metal oxides into paper-based materials, the filtration performance and antiviral capabilities of these materials can be improved. However, preliminary studies have revealed that nanoscale functional materials are difficult to integrate efficiently with paper-based materials, resulting in problems such as difficulty in co-processing functional materials with paper fibers, unstable bonding, high loss rates, and alterations in chemical structure.

[0022] Therefore, achieving efficient composites of nanoscale functional materials such as MOFs and nano-metal oxides with paper substrates is of great significance for preparing green and biodegradable air filter materials that meet protection requirements.

[0023] This invention discloses a method for preparing paper-based air filter materials using gel-loaded nanofunctional substances, which mainly includes the following processes: Preparation of ZIF-8 / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; the carboxymethyl cellulose accounted for 0.05% to 0.09% of the total mass of the final solution.

[0024] Add Zn(NO3)2·6H2O to the solution and stir thoroughly until completely dissolved; while stirring at high speed, add dilute hydrochloric acid dropwise to the solution to lower the pH value until carboxymethyl cellulose forms gel particles; The ligand 2-methylimidazole of ZIF-8 was dissolved in deionized water to obtain an aqueous solution of 2-methylimidazole. Containing Zn 2+ The carboxymethyl cellulose hydrogel was transferred into an aqueous solution of 2-methylimidazole to obtain a suspension containing the gel. The suspension containing the gel was transferred to a hydrothermal reactor to generate ZIF-8 / carboxymethyl cellulose composite gel particles.

[0025] In the ZIF-8 / carboxymethyl cellulose composite gel particles, the mass ratio of ZIF-8 to carboxymethyl cellulose is 0.5:1 to 5:1, and the resulting ZIF-8 / carboxymethyl cellulose composite gel particles have a particle size of 20 to 50 μm.

[0026] Preparation of ZnO / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; the carboxymethyl cellulose accounted for 0.05% to 0.09% of the total mass of the final solution.

[0027] ZnO nanoparticles were added to the solution and dispersed with ultrasonic assistance to ensure uniform dispersion of ZnO nanoparticles in the carboxymethyl cellulose solution, thus obtaining a suspension. Dilute hydrochloric acid solution was added dropwise to the suspension under high-speed stirring to generate ZnO / carboxymethyl cellulose composite gel particles.

[0028] In the ZnO / carboxymethyl cellulose composite gel particles, the mass ratio of nano-ZnO to carboxymethyl cellulose is 0.1:1 to 8:1, and the particle size of the resulting ZnO / carboxymethyl cellulose composite gel particles is 20 to 50 μm.

[0029] Papermaking and forming: The loosened softwood pulp was thoroughly mixed with ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles, and then added to a paper form generator. A forming wire was used to form a paper with a target basis weight of 20-30 g / m³. 2 The wet paper sheet; The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The process conditions for simultaneous freeze drying are: drying temperature -70 ~ -50 ℃, vacuum degree 5 ~ 20 Pa, and drying time 4 ~ 12 h; finally, composite paper is obtained.

[0030] The mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles is 5:1 to 1:5.

[0031] The total mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel to the mass ratio of fiber in softwood pulp is 1:10~4:10.

[0032] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0033] Example 1 A method for preparing paper-based air filter materials using gel-loaded nanofunctional materials mainly includes the following core steps: (1) Preparation of ZIF-8 / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.05% of the total mass of the final solution. Zn(NO3)2·6H2O was added to the solution and stirred thoroughly until completely dissolved. Under high-speed stirring, dilute hydrochloric acid was added dropwise to lower the pH of the solution until the carboxymethyl cellulose formed gel particles, yielding a solution containing Zn. 2+ Carboxymethyl cellulose hydrogel; Dissolve the ZIF-8 ligand 2-methylimidazole in deionized water; dissolve the Zn-containing... 2+ The carboxymethyl cellulose hydrogel was transferred into a 2-methylimidazole aqueous solution; the suspension containing the gel was transferred to a hydrothermal reactor to generate ZIF-8 / carboxymethyl cellulose composite gel particles.

[0034] The ZIF-8 to carboxymethyl cellulose mass ratio is 5:1, and the resulting composite gel particles have an average particle size of approximately 20 μm.

[0035] (2) Preparation of ZnO / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.05% of the total mass of the final solution. ZnO nanoparticles were added and dispersed with ultrasonic assistance to ensure uniform dispersion of ZnO nanoparticles in the carboxymethyl cellulose solution; under high-speed stirring, dilute hydrochloric acid solution was added dropwise to the suspension to generate ZnO / carboxymethyl cellulose composite gel particles.

[0036] The mass ratio of nano-ZnO to carboxymethyl cellulose is 5:1, and the average particle size of the resulting composite gel particles is about 20 μm.

[0037] (3) Papermaking and forming: The loosened softwood pulp was thoroughly mixed with ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles, and then added to a paper form generator. A forming wire was used to form a paper with a target basis weight of 20 g / m³. 2 The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The simultaneous freeze drying process conditions are: drying temperature -70 ℃, vacuum degree 5 Pa, and drying time 6 h; finally, composite paper is obtained.

[0038] The mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles is 1:1.

[0039] The total mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel to the fiber mass ratio in the slurry is 4:10.

[0040] The composite paper-based material prepared in this embodiment was scanned by electron microscopy to obtain the following results: Figure 1 The image shown is a scanning electron microscope image. Among them, Figure 1 Figure (a) shows the surface microstructure of the paper-based material; Figures (b) and (c) show the ZIF-8 / carboxymethyl cellulose composite gel attached to the fibers within the paper-based material; Figure (d) shows the cross-sectional microstructure of the paper-based material; Figures (e) and (f) show the ZnO / carboxymethyl cellulose composite gel attached to the fibers within the paper-based material.

[0041] Example 2 A method for preparing paper-based air filter materials using gel-loaded nanofunctional materials mainly includes the following core steps: (1) Preparation of ZIF-8 / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.06% of the total mass of the final solution. Zn(NO3)2·6H2O was added to the solution and stirred thoroughly until completely dissolved; under high-speed stirring, dilute hydrochloric acid was added dropwise to lower the pH of the solution until the carboxymethyl cellulose formed gel particles; the ligand 2-methylimidazole of ZIF-8 was dissolved in deionized water; the solution containing Zn... 2+ The carboxymethyl cellulose hydrogel was transferred into a 2-methylimidazole aqueous solution; the suspension containing the gel was transferred to a hydrothermal reactor to generate ZIF-8 / carboxymethyl cellulose composite gel particles.

[0042] The mass ratio of ZIF-8 to carboxymethyl cellulose is 0.5:1, and the average particle size of the resulting composite gel particles is approximately 20 μm.

[0043] (2) Preparation of ZnO / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.06% of the total mass of the final solution. ZnO nanoparticles were added and dispersed with ultrasonic assistance to ensure uniform dispersion of ZnO nanoparticles in the carboxymethyl cellulose solution; under high-speed stirring, dilute hydrochloric acid solution was added dropwise to the suspension to generate ZnO / carboxymethyl cellulose composite gel particles.

[0044] The mass ratio of nano-ZnO to carboxymethyl cellulose was 0.1:1, and the average particle size of the resulting composite gel particles was approximately 20 μm.

[0045] (3) Papermaking and forming: The loosened softwood pulp was thoroughly mixed with ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles, and then added to a paper form generator. A forming wire was used to form a paper with a target basis weight of 20 g / m³. 2 The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The simultaneous freeze drying process conditions are: drying temperature -50 ℃, vacuum degree 20 Pa, and drying time 4 h; finally, composite paper is obtained.

[0046] The mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles is 5:1.

[0047] The total mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel to the fiber mass ratio in the slurry is 1:10.

[0048] Example 3 A method for preparing paper-based air filter materials using gel-loaded nanofunctional materials mainly includes the following core steps: (1) Preparation of ZIF-8 / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.09% of the total mass of the final solution. Zn(NO3)2·6H2O was added to the solution and stirred thoroughly until completely dissolved; under high-speed stirring, dilute hydrochloric acid was added dropwise to lower the pH of the solution until the carboxymethyl cellulose formed gel particles; the ligand 2-methylimidazole of ZIF-8 was dissolved in deionized water; the solution containing Zn... 2+ The carboxymethyl cellulose hydrogel was transferred into a 2-methylimidazole aqueous solution; the suspension containing the gel was transferred to a hydrothermal reactor to generate ZIF-8 / carboxymethyl cellulose composite gel particles.

[0049] The ZIF-8 to carboxymethyl cellulose mass ratio is 5:1, and the resulting composite gel particles have an average particle size of approximately 50 μm.

[0050] (2) Preparation of ZnO / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.09% of the total mass of the final solution. ZnO nanoparticles were added and dispersed with ultrasonic assistance to ensure uniform dispersion of ZnO nanoparticles in the carboxymethyl cellulose solution; under high-speed stirring, dilute hydrochloric acid solution was added dropwise to the suspension to generate ZnO / carboxymethyl cellulose composite gel particles.

[0051] The mass ratio of nano-ZnO to carboxymethyl cellulose was 8:1, and the average particle size of the resulting composite gel particles was approximately 50 μm.

[0052] (3) Papermaking and forming: The loosened softwood pulp was thoroughly mixed with ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles, and then added to a paper form generator. A forming wire was used to form a paper with a target basis weight of 30 g / m³. 2 The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The simultaneous freeze drying process conditions are: drying temperature -70℃, vacuum degree 5 Pa, and drying time 12 h; finally, composite paper is obtained.

[0053] The mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles is 5:1.

[0054] The total mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel to the fiber mass ratio in the slurry is 4:10.

[0055] Example 4 The difference from Example 1 is that: The mass ratio of ZIF-8 to carboxymethyl cellulose is 3:1.

[0056] The mass ratio of nano-ZnO to carboxymethyl cellulose is 2:1.

[0057] The mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles is 1:5.

[0058] The total mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel to the fiber mass in the slurry is 2:10.

[0059] Example 5 The difference from Example 1 is that: The mass ratio of ZIF-8 to carboxymethyl cellulose is 4:1.

[0060] The mass ratio of nano-ZnO to carboxymethyl cellulose is 3:1.

[0061] The mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles is 3:1.

[0062] The total mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel to the fiber mass in the slurry is 3:10.

[0063] Comparative Example 1 A method for preparing paper-based air filter material containing ZnO nanoparticles and ZIF-8, but without using a gel carrier method, using sodium carboxymethyl cellulose as a retention aid, mainly includes the following core steps: (1) Preparation of sodium carboxymethyl cellulose solution: Dissolve sodium carboxymethyl cellulose powder in deionized water to form a solution; carboxymethyl cellulose accounts for 0.05% of the total mass of the final solution.

[0064] (2) Papermaking and forming: The loosened softwood pulp is mixed evenly with ZIF-8 and ZnO nanoparticles. Sodium carboxymethyl cellulose solution is added as a retention aid and mixed evenly. The mixture is then added to a paper sample take-up apparatus and formed using a forming wire to produce paper with a target basis weight of 20 g / m³. 2 The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The simultaneous freeze drying process conditions are: drying temperature -70 ℃, vacuum degree 5 Pa, and drying time 6 h; finally, composite paper is obtained.

[0065] The mass ratio of ZIF-8 to ZnO nanoparticles is 1:1, the total mass ratio of ZIF-8 and ZnO to sodium carboxymethyl cellulose is 5:1, and the total mass ratio of ZIF-8, ZnO, and carboxymethyl cellulose to the fiber mass ratio in the slurry is 4:10.

[0066] Comparative Example 2 A method for preparing paper-based air filter material using gel-loaded nanofunctional materials, but containing only ZIF-8, mainly includes the following core steps: (1) Preparation of ZIF-8 / carboxymethyl cellulose composite gel particles: Dissolve sodium carboxymethyl cellulose powder in deionized water to form a solution; carboxymethyl cellulose accounts for 0.05% of the total mass of the final solution. Add Zn(NO3)2·6H2O to the solution and stir thoroughly until completely dissolved; under high-speed stirring, add dilute hydrochloric acid dropwise to the solution to lower the pH value until carboxymethyl cellulose forms gel particles; dissolve the ligand 2-methylimidazole of ZIF-8 in deionized water; add Zn... 2+ The carboxymethyl cellulose hydrogel was transferred into a 2-methylimidazole aqueous solution; the suspension containing the gel was transferred to a hydrothermal reactor to generate ZIF-8 / carboxymethyl cellulose composite gel particles.

[0067] The ZIF-8 to carboxymethyl cellulose mass ratio is 5:1, and the resulting composite gel particles have an average particle size of approximately 20 μm.

[0068] (2) Papermaking and forming: The loosened softwood pulp and ZIF-8 / carboxymethyl cellulose composite gel particles are mixed evenly and added to the paper sample take-up device. The paper is then formed using a forming wire to achieve a target basis weight of 20 g / m³. 2 The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The simultaneous freeze drying process conditions are: drying temperature -70 ℃, vacuum degree 5 Pa, and drying time 6 h; finally, composite paper is obtained.

[0069] The mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles to the fiber mass in the slurry is 4:10.

[0070] Comparative Example 3 A method for preparing paper-based air filter material using gel-loaded nanofunctional materials, but containing only ZnO nanoparticles, mainly includes the following core steps: (1) Preparation of ZnO / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.05% of the total mass of the final solution. ZnO nanoparticles were added and dispersed with ultrasonic assistance to make the ZnO nanoparticles uniformly dispersed in the carboxymethyl cellulose solution; under high-speed stirring, dilute hydrochloric acid solution was added dropwise to the suspension to generate ZnO / carboxymethyl cellulose composite gel particles.

[0071] The mass ratio of nano-ZnO to carboxymethyl cellulose is 5:1, and the average particle size of the resulting composite gel particles is about 20 μm.

[0072] (2) Papermaking and forming: The loosened softwood pulp and ZnO / carboxymethyl cellulose composite gel particles are mixed evenly and added to the paper sample take-up device. The paper is then formed using a forming wire to achieve a target basis weight of 20 g / m³. 2 The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The simultaneous freeze drying process conditions are: drying temperature -70 ℃, vacuum degree 5 Pa, and drying time 6 h; finally, composite paper is obtained.

[0073] The mass ratio of the ZnO / carboxymethyl cellulose composite gel to the fiber mass in the slurry is 4:10.

[0074] Comparative Example 4 A method for preparing paper-based air filter material using gel-loaded nanofunctional materials, wherein the metal oxide nanoparticles contained are CuO and the MOFs contained are ZIF-67.

[0075] (1) Preparation of ZIF-67 / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.05% of the total mass of the final solution. Co(NO3)2·6H2O was added to the solution and stirred thoroughly until completely dissolved; under high-speed stirring, dilute hydrochloric acid was added dropwise to the solution to lower the pH value until carboxymethyl cellulose formed gel particles; the ligand 2-methylimidazole of ZIF-67 was dissolved in deionized water; the solution containing Co 2+ The carboxymethyl cellulose hydrogel was transferred into a 2-methylimidazole aqueous solution; the suspension containing the gel was transferred to a hydrothermal reactor to generate ZIF-67 / carboxymethyl cellulose composite gel particles.

[0076] The ZIF-67 to carboxymethyl cellulose mass ratio is 5:1, and the resulting composite gel particles have an average particle size of approximately 20 μm.

[0077] (2) Preparation of CuO / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder was dissolved in deionized water to form a solution; carboxymethyl cellulose accounted for 0.05% of the total mass of the final solution. CuO nanoparticles were added and dispersed with ultrasonic assistance to make the CuO nanoparticles uniformly dispersed in the carboxymethyl cellulose solution; under high-speed stirring, dilute hydrochloric acid solution was added dropwise to the suspension to generate CuO / carboxymethyl cellulose composite gel particles.

[0078] The mass ratio of nano-CuO to carboxymethyl cellulose is 5:1, and the average particle size of the resulting composite gel particles is about 20 μm.

[0079] (3) Papermaking and forming: The loosened softwood pulp is mixed evenly with ZIF-67 / carboxymethyl cellulose composite gel particles and CuO / carboxymethyl cellulose composite gel particles, and then added to the paper sample take-up device. The paper is then formed using a forming wire to achieve a target basis weight of 20 g / m³. 2 The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The simultaneous freeze drying process conditions are: drying temperature -70 ℃, vacuum degree 5 Pa, and drying time 6 h; finally, composite paper is obtained.

[0080] The mass ratio of ZIF-67 / carboxymethyl cellulose composite gel particles and CuO / carboxymethyl cellulose composite gel particles is 1:1.

[0081] The total mass ratio of ZIF-67 / carboxymethyl cellulose composite gel particles and CuO / carboxymethyl cellulose composite gel to the fiber mass in the slurry is 4:10.

[0082] Comparative Example 5 A method for preparing paper-based air filter material using gel-loaded nanofunctional materials, but the gel used is chitosan gel.

[0083] (1) Preparation of ZIF-8 / chitosan composite gel particles: Chitosan powder was dissolved in dilute acetic acid aqueous solution to form a chitosan solution, wherein acetic acid accounted for 1% of the total mass of the solution; chitosan accounted for 0.05% of the total mass of the final solution. Zn(NO3)2·6H2O was added to the solution and stirred thoroughly until completely dissolved; sodium hydroxide solution was added dropwise to the solution under high-speed stirring to raise the pH value of the solution until chitosan formed gel particles; the ligand 2-methylimidazole of ZIF-8 was dissolved in deionized water; the Zn-containing 2+ The chitosan hydrogel was transferred into a 2-methylimidazole aqueous solution; the suspension containing the gel was transferred to a hydrothermal reactor to generate ZIF-8 / chitosan composite gel particles.

[0084] The ZIF-8 to chitosan mass ratio is 5:1, and the resulting composite gel particles have an average particle size of approximately 100 μm.

[0085] (2) Preparation of ZnO / chitosan composite gel particles: Chitosan powder was dissolved in dilute acetic acid aqueous solution to form a chitosan solution, wherein acetic acid accounted for 1% of the total mass of the solution and chitosan accounted for 0.05% of the total mass of the final solution. ZnO nanoparticles were added and dispersed with ultrasonic assistance to make the ZnO nanoparticles uniformly dispersed in the chitosan solution; sodium hydroxide solution was added dropwise to the solution under high-speed stirring to raise the pH value of the solution until the chitosan formed gel particles, thus generating ZnO / chitosan composite gel particles.

[0086] The mass ratio of nano-ZnO to chitosan is 5:1, and the average particle size of the resulting composite gel particles is about 100 μm.

[0087] (3) Papermaking and forming: The loosened softwood pulp is mixed evenly with ZIF-8 / chitosan composite gel particles and ZnO / chitosan composite gel particles, and then added to the paper sample take-up device. The paper is then formed using a forming wire to achieve a target basis weight of 20 g / m³. 2 The wet paper web is then transferred to a freeze dryer for simultaneous freeze drying. The simultaneous freeze drying process conditions are: drying temperature -70 ℃, vacuum degree 5 Pa, and drying time 6 h; finally, composite paper is obtained.

[0088] The mass ratio of ZIF-8 / chitosan composite gel particles and ZnO / chitosan composite gel particles is 1:1.

[0089] The total mass ratio of ZIF-8 / chitosan composite gel particles and ZnO / chitosan composite gel to the mass ratio of fiber in the slurry is 4:10.

[0090] The key parameters of the samples obtained in Examples 1-5 and Comparative Examples 1-5 are summarized in Table 1: Table 1. List of key parameters for the examples and comparative samples

[0091] The samples prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests. The air filtration performance test conditions were: NaCl aerosol, face velocity 5.33 cm / s, and PM2.5 concentration. 2.5 Taking filtration efficiency as an example, the antibacterial test was conducted using the inhibition zone method, with the test method being GB / T 38483-2020. The diameter of the inhibition zone was recorded after 24 hours.

[0092] Based on the test results, the technical effects of the present invention are analyzed as shown in Table 2.

[0093] Table 2. Performance Comparison of Examples and Comparative Samples

[0094] 1. Necessity Analysis of Gel Loading Examples 1-5, which employ the gel loading method described in this invention, exhibit significantly superior overall performance compared to Comparative Example 1, which does not use gel loading. Specifically, in the sample obtained in Example 1, the retention rates of ZIF-8 and ZnO are higher. ZIF-8 can effectively improve the filtration efficiency of paper-based materials and reduce filtration resistance, achieving a high filtration efficiency of 95.3% while controlling the filtration resistance at 120 Pa and an inhibition zone of 12.2 mm. In contrast, Comparative Example 1 experiences greater loss of ZIF-8 and ZnO during the papermaking process, resulting in a filtration efficiency of only 72.8%, a resistance of 174 Pa, and an inhibition zone of 10.0 mm.

[0095] The two functional substances, loaded onto a gel, can directly participate in the papermaking process, avoiding loss, mutual interference, and alteration of chemical structure; furthermore, the loss rate of functional substances during paper-based material preparation is lower. This enables efficient utilization of functional substances, resulting in better filtration performance and pathogen inhibition effects.

[0096] 2. Synergistic effect analysis of metal oxide particles and MOFs By comparing the performance data of Example 1 with Comparative Examples 2 and 3, the synergistic effect of ZnO and ZIF-8 can be analyzed: Although the filtration efficiency of Comparative Example 2 (without ZnO) is similar to that of Example 1 (94.7%), its inhibition zone diameter is only 7.3 mm, and its antibacterial performance is significantly inferior to that of Example 1 (12.2 mm), proving that ZnO is crucial for endowing the material with excellent antibacterial / antiviral capabilities. The filtration efficiency of Comparative Example 3 (without ZIF-8) drops sharply to 68.4%, and its filtration resistance is the highest (179 Pa), proving that ZIF-8, with its porous structure and adsorption properties, plays a key role in improving particulate matter capture efficiency and optimizing the material's pore structure to reduce resistance.

[0097] Example 1 combines the advantages of both, achieving a balance between high filtration efficiency (95.3%), moderate filtration resistance (120 Pa), and strong antibacterial properties (12.2 mm inhibition zone), demonstrating a synergistic enhancement effect between ZnO and ZIF-8. The zinc-based MOF and nano-ZnO exhibit excellent bandgap matching and interfacial compatibility due to their shared metal center, promoting the migration and separation of photogenerated electrons and improving the efficiency of photocatalytic generation of reactive oxygen species. The porous zinc-based MOF, acting as a "nanocontainer," efficiently adsorbs and concentrates pathogens and pollutants in the air, providing a high-concentration reaction microenvironment for nano-ZnO, thereby achieving a highly efficient purification path of "enrichment followed by degradation."

[0098] 3. Technical Effect Analysis of Material Biosafety and Appearance Example 1 uses a full zinc-based system (ZnO and ZIF-8), resulting in a white paper-based material that meets the appearance requirements of personal protective equipment, and zinc has good biocompatibility. Comparative Example 4, while exhibiting excellent filtration efficiency (96.4%) and antibacterial properties (13.0 mm), uses potentially biotoxic metals such as cobalt and copper, resulting in a dark gray material that limits its application in high-end, safety-critical personal protective equipment. This invention balances high performance with biosafety and product aesthetics.

[0099] 4. Analysis of gel particle size and its binding state with cellulose fibers Example 1 used carboxymethyl cellulose, resulting in composite gel particles with an average particle size of approximately 20 μm; Comparative Example 2 used chitosan, resulting in composite gel particles with an average particle size of approximately 100 μm. Example 1 outperformed Comparative Example 5 in both filtration efficiency (95.3% vs 93.1%) and filtration resistance (120 Pa vs 152 Pa). Smaller composite gel particles are more advantageous for the uniform distribution of functional substances in the paper matrix. Due to molecular structural similarity, carboxymethyl cellulose gel particles bind more tightly to cellulose fibers, which is more conducive to the stable bonding of functional substances with the paper matrix material.

[0100] In summary, this invention, through its unique structural design, achieves unexpected technical effects: it enables the efficient composite of nanoscale functional materials such as MOFs and nano-metal oxides with paper substrates, thereby improving the filtration performance and antiviral capabilities of paper-based materials. Examples 1 to 5 demonstrate that, within the parameter range of this invention, the overall performance is superior to that of the comparative examples, proving the universality of the technical solution. These advancements are unattainable by conventional technical solutions represented by the comparative examples, fully demonstrating the inventiveness of this invention.

[0101] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A paper-based air filtration material loaded with nano-functional substances using a gel, characterized by, The application discloses a method for realizing the compounding of paper-based materials by loading nano functional substances on natural polymer hydrogels. The nano functional substances comprise metal oxide nanoparticles and metal organic framework compounds; the metal oxide nanoparticles are ZnO nanoparticles; and the metal organic framework compounds are ZIF-8, which is synthesized in situ.

2. The paper-based air filtration material loaded with nano-functional substances using gel according to claim 1, characterized in that, The natural polymer used in the hydrogel is carboxymethyl cellulose.

3. A method for preparing a paper-based air filtration material loaded with nano-functional substances using a gel, characterized by, The method comprises the following steps: Preparation of ZIF-8 / carboxymethyl cellulose composite gel particles: Sodium carboxymethyl cellulose powder is dissolved in deionized water to form a solution; a Zn salt is added to the solution, and stirred thoroughly until completely dissolved; while stirring, an acidic solution is added dropwise to the solution until the carboxymethyl cellulose forms gelled particles, resulting in a carboxymethyl cellulose hydrogel containing Zn 2+ ​ Carboxymethylcellulose hydrogel containing Zn 2+ is added to an aqueous solution of 2-methylimidazole to obtain a suspension; Hydrothermal reaction of the suspension to generate ZIF-8 / carboxymethyl cellulose composite gel particles; Preparation of ZnO / carboxymethyl cellulose composite gel particles: Dissolution of sodium carboxymethyl cellulose powder in deionized water to form a solution; Addition of ZnO nanoparticles and ultrasonic-assisted dispersion to obtain a suspension; Under stirring, the suspension is added with an acidic solution to generate ZnO / carboxymethyl cellulose composite gel particles; Papermaking and shaping: The defibered softwood pulp was mixed with the ZIF-8 / carboxymethyl cellulose composite gel particles and the ZnO / carboxymethyl cellulose composite gel particles uniformly, and a wet paper web with a target basis weight of 20-30 g / m2was made; the wet paper web was then subjected to simultaneous freeze-drying, and finally a paper-based air filtration material was obtained. 2 The defibered softwood pulp was mixed with the ZIF-8 / carboxymethyl cellulose composite gel particles and the ZnO / carboxymethyl cellulose composite gel particles uniformly, and a wet paper web with a target basis weight of 20-30 g / m2was made; the wet paper web was then subjected to simultaneous freeze-drying, and finally a paper-based air filtration material was obtained.

4. The production method according to claim 3, characterized by, In the preparation of ZIF-8 / carboxymethyl cellulose composite gel particles and the preparation of ZnO / carboxymethyl cellulose composite gel particles, the mass fraction of carboxymethyl cellulose in the solution is 0.05%-0.09%.

5. The production method according to claim 3, characterized by, In the ZIF-8 / carboxymethyl cellulose composite gel particles, the mass ratio of ZIF-8 to carboxymethyl cellulose is 0.5:1-5:1, and the particle size is 20-50 μm.

6. The production method according to claim 3, characterized by, In the ZnO / carboxymethyl cellulose composite gel particles, the mass ratio of nano ZnO to carboxymethyl cellulose is 0.1:1-8:1, and the particle size is 20-50 μm.

7. The preparation method according to claim 3, characterized in that, In the papermaking and shaping, the mass ratio of ZIF-8 / carboxymethyl cellulose composite gel particles to ZnO / carboxymethyl cellulose composite gel particles is 5:1-1:

5.

8. The preparation method according to claim 3, characterized in that, In the papermaking and shaping, the mass ratio of the total amount of ZIF-8 / carboxymethyl cellulose composite gel particles and ZnO / carboxymethyl cellulose composite gel particles to the fibers in the coniferous wood pulp is 1:10-4:

10.

9. The production method according to claim 3, characterized by, The process conditions of the simultaneous freeze drying are as follows: a drying temperature of -70 to -50 ℃, a vacuum degree of 5-20 Pa and a drying time of 4-12 h.

10. Use of the paper-based air filtration material loaded with gel and nano functional substances according to claim 1 or 2 in the preparation of a mask.

Images