An antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots and its preparation method

Abstract

This invention relates to the field of protective equipment technology, specifically disclosing an antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots and its preparation method. The mask contains a modified functional layer composed of a fiber substrate, coal-based humic acid-derived carbon dots, and an environmentally friendly water-based polymer, which is firmly attached to the fiber surface and pores. The preparation includes carbon dot synthesis and purification, preparation of dispersion and functional finishing liquid, functionalization treatment of the fiber substrate, drying and curing, and composite assembly of the mask. Processes such as impregnation, spraying, and padding can be used, and the process is compatible with existing production lines. This mask achieves synergistic protection through physical interception and chemical elimination, exhibiting highly efficient and broad-spectrum antibacterial and antiviral activity with long-lasting performance, good biocompatibility, readily available and low-cost raw materials, and excellent breathability and filtration efficiency. It is suitable for personal protection, medical care, and public health fields.

Description

Technical Field

[0001] This invention belongs to the field of protective equipment technology, specifically relating to a mask with long-lasting antibacterial and antiviral functions and its preparation method. In particular, it relates to using coal-based humic acid (lignite) derived carbon dots (HACDs) as functional additives, and combining them with mask materials through a specific process to endow the mask with efficient and long-lasting antibacterial and antiviral properties. Background Technology

[0002] Face masks, as essential personal protective equipment, play a crucial role in preventing the spread of respiratory diseases and filtering air pollutants. Traditional medical masks and non-woven masks primarily intercept particulate matter and droplets through physical barriers, but they lack the ability to actively kill or inhibit microorganisms (including bacteria and viruses). During prolonged wear, microorganisms can easily accumulate on the surface of the mask, potentially becoming a source of secondary contamination, reducing its protective effectiveness, and even causing skin discomfort for the wearer.

[0003] To improve this problem, the following methods are commonly used in existing technologies to impart antibacterial function to masks: (1) Adding inorganic antibacterial agents: such as metal ions or oxides of silver, copper, zinc, etc. Although these materials have certain antibacterial effects, they have potential biotoxicity, are prone to discoloration, are expensive, and are prone to falling off and becoming ineffective after long-term use or washing. (2) Loading organic antibacterial agents: such as quaternary ammonium salts, chlorhexidine, etc. These antibacterial agents take effect quickly, but may have drug resistance, poor durability, limited effect on specific viruses, and some organic molecules may cause skin irritation or allergies. (3) Photocatalytic materials: such as TiO2. They need to be activated under specific light (especially ultraviolet light), and their effect is limited in environments with insufficient light, such as indoors or at night. The potential inhalation risk of nanoparticles needs to be carefully assessed.

[0004] In addition, existing antibacterial modifications mostly focus on bacteria, and the research on their targeted inactivation ability and mechanism of action against viruses (especially enveloped viruses) is not in-depth enough, making it difficult to meet the urgent need for efficient protection against viruses.

[0005] Coal-based humic acid (CBHA) is a natural organic macromolecule extracted from low-rank coals such as lignite and weathered coal. It is widely available, inexpensive, and rich in active functional groups such as carboxyl and phenolic hydroxyl groups. Carbon dots (HACDs) derived from CBHA not only inherit some functional group characteristics of humic acid but also possess nanoscale size, good water dispersibility, low toxicity, and unique optical and electronic properties. In particular, CBHA itself contains certain minerals and aromatic structures, and its derived carbon dots may have richer surface chemical and electronic properties, showing potential in antibacterial and antiviral applications. Recent studies have shown that carbon dots with certain structures can exhibit broad-spectrum antibacterial activity through mechanisms such as physical destruction and oxidative stress. However, how to effectively, firmly, and uniformly integrate this novel material, HACDs, into porous and soft fiber-based materials like face masks to construct a "smart" protective mask that combines highly efficient physical filtration with active chemical and biological inactivation functions has not yet been reported. Meanwhile, developing a simple modification method that is applicable to existing mask production lines and can maintain the basic comfort and breathability of masks is also key to its industrialization.

[0006] Therefore, developing a mask product based on coal-based humic acid-derived carbon dots with long-lasting, broad-spectrum, safe antibacterial and antiviral functions, and its efficient preparation technology, has important practical value and social significance. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology and propose an antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots and its preparation method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: An antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots, the mask comprising at least one modified functional layer, the functional layer being composed of a fiber substrate and coal-based humic acid-derived carbon dots loaded thereon and an adhesive; the coal-based humic acid-derived carbon dots are prepared by hydrothermal method from humic acid extracted from lignite or weathered coal, the coal-based humic acid-derived carbon dots being firmly attached to the surface and pores of the fiber substrate.

[0009] Preferably, the fiber substrate is meltblown nonwoven fabric, spunbond nonwoven fabric, cotton fabric, or a composite layer of these materials.

[0010] Preferably, the load of the HACDs is 1% to 10% based on the total mass of the functional layer.

[0011] Preferably, the binder is an environmentally friendly waterborne polymer, including but not limited to waterborne emulsions of polyacrylate, polyvinyl alcohol, polyurethane, or chitosan.

[0012] The above-mentioned method for preparing an antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots includes the following steps: S1: Preparation of coal-based humic acid-derived carbon dots. Coal-based humic acid extracted from lignite or weathered coal is used as raw material. Coal-based humic acid-derived carbon dots are synthesized by hydrothermal method. After the reaction is completed, the carbon dots are cooled, filtered, purified by dialysis and dried to obtain solid powder of coal-based humic acid-derived carbon dots. S2: Prepare the dispersion by dispersing the coal-based humic acid-derived carbon dot solid powder obtained in step S1 in deionized water or ethanol-water mixed solvent to prepare a dispersion with a concentration of 0.1-20 mg / mL, and then subjecting it to ultrasonic treatment to obtain a uniform and stable dispersion. S3: Prepare the functional finishing liquid by mixing the dispersion obtained in step S2 with the binder in a certain proportion, adding an appropriate amount of wetting agent, and stirring evenly to form the functional finishing liquid; wherein, the solid mass ratio of coal-based humic acid-derived carbon dots to binder is in the range of 1:1 to 1:20. S4: Perform functional treatment on the fiber substrate by immersing the fiber substrate for the mask in the functional finishing liquid prepared in step S3, or by spraying or scraping the functional finishing liquid evenly onto the fiber substrate. S5: Drying and curing are carried out. The treated fiber substrate is dried at 60-120℃ to cure the adhesive, thereby firmly fixing the coal-based humic acid-derived carbon dots on the surface of the fiber substrate to form a functional layer. S6: The processed functional layer is combined with other necessary layers according to the conventional mask production process, including compounding, cutting, welding, and assembly, to produce the finished antibacterial and antiviral mask.

[0013] Preferably, in step S4, an impregnation process is used: the fiber substrate is immersed in the functional finishing liquid, and the liquid carrying rate is controlled at 50%-150% by the rollers, and then the drying and curing process is carried out in step S5.

[0014] Preferably, in step S4, a spraying process is used: the functional finishing liquid is uniformly atomized through a nozzle and sprayed onto the surface of the fiber substrate, and the spraying amount per unit area is controlled to be 5-10 mL / m²; the fiber substrate is meltblown nonwoven fabric, spunbond nonwoven fabric, cotton fabric or a composite layer of these materials.

[0015] Preferably, the purity of the coal-based humic acid in step S1 is not less than 90%, and the hydrothermal method specifically involves dispersing the coal-based humic acid in water at a reaction temperature of 180-220°C and a reaction time of 4-10 hours. The wetting agent can be a nonionic surfactant. In step S6, other necessary layers can be an inner skin-friendly nonwoven fabric, an outer waterproof nonwoven fabric, a nose bridge strip, and ear loops.

[0016] The antibacterial and antiviral masks prepared by the above-mentioned method based on coal-based humic acid-derived carbon dots can be used in the fields of personal protection, medical care, or public health.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention has efficient and broad-spectrum antibacterial and antiviral capabilities. The HACDs prepared from coal-based humic acid are rich in active functional groups such as carboxyl groups and phenolic hydroxyl groups on their surface. They may contain specific mineral components derived from coal matrix, which enable them to achieve efficient and broad-spectrum inactivation of bacteria (such as Staphylococcus aureus and Escherichia coli) and viruses (such as influenza virus and coronavirus enveloped viruses) through multiple synergistic mechanisms such as physical destruction of microbial cell membranes / virus envelopes and induction of oxidative stress.

[0018] (2) The raw materials of the present invention are low in cost and have stable sources. Coal-based humic acid (especially lignite) is abundant in my country and is inexpensive. Using it as a raw material to prepare HACDs can significantly reduce the cost of functional additives, and the source and quality of the raw materials are stable and controllable.

[0019] (3) The HACDs of the present invention are firmly anchored to the fiber by chemical and physical means through environmentally friendly adhesives. They are resistant to friction from conventional airflow and certain humidity environments, and are not easy to fall off, thus ensuring the durability of the function. Coal-based humic acid, as a natural extract, has good biocompatibility and low cytotoxicity after its derived carbon dots are fully purified, making it safe to use.

[0020] (4) The finishing processes such as impregnation and spraying provided by the present invention are simple and easy to integrate into existing nonwoven fabric production or mask processing. The functional finishing liquid has good permeability and can form a uniform and firm modified layer on the fiber surface. By controlling the load, the blockage of fiber pores can be minimized, thereby basically maintaining the original breathability, filtration efficiency and comfort of the mask.

[0021] (5) The main raw material of this invention, coal-based humic acid, is widely available, and the hydrothermal synthesis method is green and mild. The aqueous finishing system is environmentally friendly, with no toxic solvent volatilization. The overall process cost is low, which is conducive to large-scale production and promotion.

[0022] (6) The mask of the present invention combines the physical and mechanical filtration mechanism of traditional masks with the active chemical and biological inactivation mechanism provided by HACDs, realizing the synergy of "physical interception" and "chemical killing", thereby improving the overall protective efficacy and safety of the mask. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 A schematic diagram of the hydrothermal method for preparing HACDs; Figure 2 (a) TEM images of HACDs prepared at 110°C and (b) 210°C; (c) particle size distribution curves of HACDs prepared at 210°C; (d) XRD patterns of HACDs prepared at 110°C and 210°C.

[0025] Figure 3 (a) FT-IR spectrum; (b) high-resolution C1s elemental spectrum of CBHA; (c) high-resolution C1s elemental spectrum of HACDs prepared at hydrothermal temperatures of 110 °C and (d) 210 °C. Figure 4 This is a schematic diagram of the distribution structure of HACDs in a fiber-based substrate. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] Example 1 Preparation of coal-based humic acid-derived carbon dots (HACDs): Weigh 1.0 g of coal-based humic acid powder (purity ≥90%, derived from lignite) and dissolve it in 40 mL of deionized water, stirring until completely dissolved. Transfer the solution to a 50 mL high-pressure reactor lined with polytetrafluoroethylene and react at 200 °C for 6 hours. After the reaction, allow it to cool naturally, and filter the resulting brownish-black liquid through a 0.22 μm filter membrane. Dialyze the filtrate through a dialysis bag with a molecular weight cutoff of 1000 Da for 48 hours to remove small molecule impurities and unreacted humic acid. Finally, freeze-dry the dialysate to obtain brownish-black solid HACDs powder. The specific preparation process is as follows: Figure 1 As shown. The physicochemical properties of HACDs are as follows. Figure 2 , Figure 3 As shown.

[0028] Example 2 Preparation of functional finishing solutions and functionalization of meltblown fabric (pad impregnation method): S1: Take 50 mg of HACDs powder obtained in Example 1, disperse it in 100 mL of deionized water, sonicate for 1 hour, and prepare a stable dispersion A with a concentration of 0.5 mg / mL.

[0029] S2: Measure 100 mL of water-based polyacrylate emulsion (solid content 20%) as binder B.

[0030] S3: Mix 100 mL of dispersion A with 20 mL of binder B, then add 0.1 g of nonionic surfactant (Triton X-100), and stir magnetically for 30 minutes to obtain a uniform functional finishing solution C.

[0031] S4: Take commercially available meltblown nonwoven fabric with a weight of 25 g / m² (as the middle filter layer of the mask) and pass it through a two-roller impregnation machine. Adjust the roller pressure so that the liquid retention rate of the meltblown fabric after impregnation with functional finishing liquid C is about 80%.

[0032] S5: Place the impregnated meltblown fabric into a forced-air drying oven and dry it at 90°C for 10 minutes to obtain functionalized meltblown fabric D.

[0033] Example 3 Preparation of functional finishing liquid and functionalization of nonwoven fabrics (spray coating method): S1: Using the HACDs of Example 1, prepare an aqueous dispersion of HACDs at a concentration of 1.0 mg / mL.

[0034] S2: Mix the dispersion with a 2% polyvinyl alcohol (PVA) aqueous solution at a volume ratio of 1:4, add a small amount of wetting agent, and obtain the functional finishing solution.

[0035] S3: Load the functional finishing liquid into the spray gun and spray it evenly onto the surface of the spunbond nonwoven fabric (as the outer layer of the mask). The spraying amount should be controlled at 5-10 mL / m².

[0036] S4: Dry the sprayed nonwoven fabric at 80℃ for 5 minutes to obtain the functionalized outer nonwoven fabric. A schematic diagram of the HACDs distribution structure in the fiber substrate is shown below. Figure 4 As shown.

[0037] Example 4 Assembly of antibacterial and antiviral masks: The functionalized meltblown fabric D obtained in Example 2 is used as the middle filter layer, the outer layer is the functionalized spunbond nonwoven fabric (or ordinary waterproof nonwoven fabric) obtained in Example 3, and the inner layer is ordinary skin-friendly spunbond nonwoven fabric. Following GB / T32610-2016 "Technical Specifications for Daily Protective Masks", the fabric is cut and then combined and assembled with accessories such as nose bridge strips and ear loops using an ultrasonic welding machine to obtain the finished mask.

[0038] Supplementary Examples and Comparative Examples: Study on HACDs Load Optimization To determine the optimal loading range of HACDs in the functional layer, while maintaining the same HACDs raw materials, aqueous polyacrylate binder, and padding process as in Example 2, a series of functionalized meltblown fabric samples with target HACDs mass fractions of 0.5%, 1%, 5%, 10%, 15%, and 40% were prepared by adjusting the concentration of the HACDs dispersion in the functional finishing solution and the padding liquid ratio. These samples were labeled as Comparative Example D, Example A, Example B, Example C, Comparative Example E, and Comparative Example F, respectively. Performance tests were performed on all samples, and the results are summarized in Table 1 below. Table 1 Conclusion: When the mass fraction of HACDs is in the range of 1% to 10%, the functionalized material achieves the best balance between long-lasting antibacterial and antiviral activity (maintaining an antibacterial rate of >96% and an antiviral activity value of >3.0 after washing) and basic protective performance (PFE>95%, air resistance <100Pa, and wearing comfort). Particulate Filtration Efficiency (PFE): Below 1% (e.g., 0.5%), long-lasting biological activity is insufficient; above 10% (e.g., 15%, 40%), although the initial biological activity is acceptable, it leads to a significant and unacceptable increase in air resistance and begins to affect filtration efficiency. Furthermore, at high loads (40%), there is a risk of pore blockage and potential increased toxicity, and the economics also deteriorate. Therefore, 1%-10% is the preferred and inventive range of this invention.

[0039] Comparative Example 1 Ordinary untreated meltblown fabric masks: Using the same batch of meltblown fabric as in Example 2 but without any functional finishing, masks were assembled with the same outer and inner nonwoven fabric layers.

[0040] Performance Tests and Results (1) Antibacterial properties: Referring to GB / T20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Oscillation method", the antibacterial rate of the middle layer material of the mask against Escherichia coli (ATCC25922) and Staphylococcus aureus (ATCC6538) was tested. In Example 2, the antibacterial rate of the material before washing was >99.9%, and after 10 standard washes, the antibacterial rate was still >95%. In Comparative Example 1, the material had no antibacterial activity.

[0041] (2) Antiviral performance: Referring to ISO 18184:2019 "Determination of antiviral activity of textiles", the antiviral activity of the mask material against influenza A (H1N1) virus was tested. The antiviral activity value of the material in Example 2 was >3.0 (i.e., logarithmic reduction >99.9%), indicating that it has extremely strong virus inactivation ability.

[0042] (3) Filtration performance and breathing resistance: The particulate filtration efficiency (PFE, for NaCl aerosol) and breathing resistance of the mask were tested in accordance with GB2626-2019 "Respiratory Protection Self-priming Filtering Respirators for Particulate Matter". The finished mask in Example 4 had a PFE ≥ 95% (compliant with KN95 level) and a breathing resistance of about 90 Pa. Compared with the ordinary mask in Comparative Example 1 (PFE ≥ 95%, resistance about 85 Pa), the filtration efficiency was comparable, and the breathing resistance was only slightly increased, which was within the comfortable range.

[0043] (4) Biosafety (cytotoxicity): Referring to GB / T16886.5-2017 "Biological evaluation of medical devices - Part 5: In vitro cytotoxicity test", the MTT method was used to test the toxicity of functional material extract to L929 mouse fibroblasts. The results showed that the relative cell growth rate (RGR) was ≥90%, which is non-toxic.

[0044] in conclusion The above embodiments demonstrate that the present invention successfully loads coal-based humic acid-derived carbon dots (HACDs) onto mask materials through a simple and feasible post-processing technique. The resulting masks retain their original physical protective properties (high filtration efficiency, low breathing resistance) while also possessing excellent and long-lasting active antibacterial and antiviral functions. This technology fully utilizes my country's abundant lignite resources, providing a practical solution for developing a new generation of low-cost, high-performance multifunctional protective masks.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots, characterized in that, The mask comprises at least one modified functional layer, which consists of a fiber substrate and coal-based humic acid-derived carbon dots and a binder loaded thereon; the coal-based humic acid-derived carbon dots are prepared by hydrothermal method from humic acid extracted from lignite or weathered coal, and the coal-based humic acid-derived carbon dots are firmly attached to the surface and pores of the fiber substrate.

2. The antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots according to claim 1, characterized in that, The fiber substrate is meltblown nonwoven fabric, spunbond nonwoven fabric, cotton fabric, or a composite layer of these materials.

3. The antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots according to claim 1, characterized in that, Based on the total mass of the functional layer, the mass fraction of the coal-based humic acid-derived carbon dots is 1% to 10%.

4. The antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots according to claim 1, characterized in that, The binder is an environmentally friendly waterborne polymer, including but not limited to waterborne emulsions of polyacrylate, polyvinyl alcohol, polyurethane, or chitosan.

5. A method for preparing an antibacterial and antiviral mask based on coal-based humic acid-derived carbon dots according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Preparation of coal-based humic acid-derived carbon dots. Coal-based humic acid extracted from lignite or weathered coal is used as raw material. Coal-based humic acid-derived carbon dots are synthesized by hydrothermal method. After the reaction is completed, the carbon dots are cooled, filtered, purified by dialysis and dried to obtain solid powder of coal-based humic acid-derived carbon dots. S2: Prepare the dispersion by dispersing the coal-based humic acid-derived carbon dot solid powder obtained in step S1 in deionized water or ethanol-water mixed solvent to prepare a dispersion with a concentration of 0.1-20 mg / mL, and then subjecting it to ultrasonic treatment to obtain a uniform and stable dispersion. S3: Prepare the functional finishing liquid by mixing the dispersion obtained in step S2 with the binder in a certain proportion, adding an appropriate amount of wetting agent, and stirring evenly to form the functional finishing liquid; wherein, the solid mass ratio of coal-based humic acid-derived carbon dots to binder is in the range of 1:1 to 1:

20. S4: Perform functional treatment on the fiber substrate by immersing the fiber substrate for the mask in the functional finishing liquid prepared in step S3, or by spraying or scraping the functional finishing liquid evenly onto the fiber substrate. S5: Drying and curing are carried out. The treated fiber substrate is dried at 60-120℃ to cure the adhesive, thereby firmly fixing the coal-based humic acid-derived carbon dots on the surface of the fiber substrate to form a functional layer. S6: The processed functional layer is combined with other necessary layers according to the conventional mask production process, including compounding, cutting, welding, and assembly, to produce the finished antibacterial and antiviral mask.

6. The preparation method according to claim 5, characterized in that, In step S4, an impregnation process is used: the fiber substrate is immersed in the functional finishing liquid, and the liquid carry-over rate is controlled at 50%-150% by the rollers, and then the drying and curing process is carried out in step S5.

7. The preparation method according to claim 5, characterized in that, In step S4, a spraying process is adopted: the functional finishing liquid is uniformly atomized through a nozzle and sprayed onto the surface of the fiber substrate, and the spraying amount per unit area is controlled to be 5-10 mL / m²; the fiber substrate is meltblown nonwoven fabric, spunbond nonwoven fabric, cotton fabric or a composite layer of these materials.

8. The preparation method according to claim 5, characterized in that, In step S1, the purity of the coal-based humic acid is not less than 90%. The hydrothermal method specifically involves dispersing the coal-based humic acid in water at a reaction temperature of 180-220℃ for 4-10 hours. The wetting agent can be a nonionic surfactant. In step S6, other necessary layers can be an inner skin-friendly nonwoven fabric, an outer waterproof nonwoven fabric, a nose bridge strip, and ear loops.

9. The application of an antibacterial and antiviral mask prepared by the method of any one of claims 5-8 based on coal-based humic acid-derived carbon dots in the fields of personal protection, medical care, or public health.

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