Photocatalytic self-cleaning antibacterial fabric and preparation method thereof

Abstract

The application discloses a kind of photocatalytic self-cleaning antibacterial fabric and preparation method thereof, belong to functional textile material field.The fabric is by base cloth and successively coated in the surface of base cloth fiber silane coupling layer, g-C3N4 / TiO2 heterojunction nano composite layer and hydrophilic protective layer is constituted.Preparation method includes: by hydrothermal method preparation g-C3N4 / TiO2 Composite nanoparticle;Amino-modified is carried out to base cloth;Amino-modified base cloth is dipped in containing g-C3N4 / TiO2 Composite nanoparticle and natural melanin finishing liquor, and it is loaded photocatalytic layer by two dip two rolling process;Finally, coating polyvinyl alcohol hydrophilic ultrathin protective layer and crosslinking solidification.The application is by g-C3N4 / TiO2 Heterojunction and introduction melanin, widen photoresponse range to visible light region, improve photo-generated carrier separation efficiency, realize high-efficiency degradation organic pollutant and broad-spectrum inactivation bacteria.Simultaneously, the synergistic effect of silane coupling layer and hydrophilic ultrathin protective layer will functional layer firmly anchored on the surface of fiber, give fabric excellent washability and long-acting stability.

Description

Technical Field

[0001] This invention belongs to the field of functional textile materials, specifically relating to a photocatalytic self-cleaning antibacterial fabric and its preparation method. Background Technology

[0002] Functional textile materials have significant application value in medical protective equipment, outdoor gear, and everyday wear, with their self-cleaning and antibacterial functions being a current research focus. Photocatalytic antibacterial technology is one of the main technical pathways to achieve the self-cleaning and antibacterial functions of fabrics. Its core mechanism lies in the fact that photocatalysts, upon light excitation, generate photogenerated electron-hole pairs, which then react with adsorbed oxygen or water molecules on the surface to produce reactive oxygen species such as superoxide radicals and hydroxyl radicals. These reactive oxygen species can non-selectively oxidize and destroy bacterial cell membranes, viral protein capsids, and genetic material, thereby achieving broad-spectrum and highly efficient inactivation of pathogenic microorganisms. Simultaneously, they can decompose organic stains into small molecule products.

[0003] Titanium dioxide (TiO2) is widely used in functional fabric research due to its high oxidizing activity, good chemical stability, and high biocompatibility. However, its wide bandgap (approximately 3.2 eV) means it can only respond to ultraviolet light excitation with wavelengths less than 387 nm. Since ultraviolet light constitutes only about 4% of the solar spectrum reaching the Earth's surface, the catalytic activity of the fabric drops sharply in indoor environments (primarily reliant on visible light) or under low-light outdoor conditions (such as early morning, dusk, cloudy / rainy days, and shaded areas). To overcome this limitation, researchers have turned their attention to visible-light-responsive materials, among which graphitic carbon nitride (g-C3N4) possesses visible light-trapping capabilities due to its suitable narrow bandgap (approximately 2.7 eV). However, the material has a high defect density and weak interlayer interaction in its bulk structure, making it easy for photogenerated electrons and holes to recombine and resulting in low carrier separation efficiency. This severely restricts the generation rate and concentration of reactive oxygen free radicals (such as superoxide free radicals and hydroxyl free radicals), making it difficult to reach the threshold required for rapid and thorough killing of high concentrations of bacteria and viruses within a limited light exposure time. Consequently, fabrics using g-C3N4 alone often exhibit defects such as "response without effectiveness" or slow bactericidal kinetics, failing to meet the stringent standards for efficient, broad-spectrum, and immediate bactericidal performance in medical protection and high-frequency use scenarios.

[0004] Besides the intrinsic properties of the material, the stability of the photocatalyst on the fiber surface is another core factor that determines the practicality of the fabric. Current mainstream manufacturing processes mostly rely on physical adsorption, simple padding, or polymer adhesive coating. The nano-photocatalysts (such as TiO2 and g-C3N4) lack stable chemical bonds (such as covalent or strong coordination bonds) with the textile fiber surface, relying only on weak van der Waals forces or mechanical interlocking to maintain adhesion. This fragile interface structure is extremely unstable during actual fabric use. Once subjected to continuous mechanical friction and bending deformation from daily wear, especially the shear force of water flow and chemical erosion from detergents during repeated washing, the functional coating will quickly peel off, powder, or even detach over a large area. This leads to a precipitous decline in the fabric's antibacterial and self-cleaning properties, often rendering it ineffective after only a few washes, severely shortening the product's lifespan. Even more serious is the fact that the detached nanoparticles not only waste materials but may also enter the ecological environment with wastewater discharge or enter the human body through skin contact, causing potential ecotoxicity accumulation and biosafety risks. This makes it difficult for existing technologies to simultaneously pursue high-efficiency functionality while maintaining long-term stability and environmental friendliness, failing to meet the stringent requirements of high-quality functional textiles for "washability, abrasion resistance, and long lifespan."

[0005] Furthermore, existing research and development of photocatalytic fabrics often falls into the trap of "emphasizing catalysis while neglecting cleaning," overlooking the synergistic mechanism between photocatalytic degradation and hydrophilic self-cleaning. Although photocatalysts can oxidize and decompose organic stains into smaller molecules, if the fabric surface lacks excellent hydrophilicity, the residues after degradation cannot be effectively wetted and carried away by water droplets, instead forming difficult-to-remove watermarks or secondary deposits. This not only seriously affects the fabric's aesthetics and breathability but also renders the self-cleaning function incomplete, failing to achieve true "stain removal without leaving a trace." This dual deficiency of functional limitation and potential biotoxicity makes it difficult for existing technologies to meet the comprehensive needs of modern textiles for high efficiency, safety, lasting comfort, and environmental friendliness.

[0006] Although the academic community has attempted to improve the above problems by doping or constructing heterojunctions, how to simultaneously achieve a broad spectral response (efficient utilization of visible light), rapid separation of photogenerated carriers, firm anchoring of nanocatalysts on fiber surfaces, excellent washability and self-cleaning properties in a single system remains a key technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide a photocatalytic self-cleaning antibacterial fabric and its preparation method, which can degrade organic stains and inactivate bacteria under visible light or sunlight irradiation, and has a self-cleaning function.

[0008] To address the aforementioned technical problems, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a photocatalytic self-cleaning antibacterial fabric, the method comprising the following steps:

[0010] S1. G-C3N4 powder was ultrasonically dispersed in anhydrous ethanol. Tetrabutyl titanate was slowly added dropwise under ice bath stirring, followed by the addition of deionized water and stirring to form a sol. The sol was then subjected to hydrothermal treatment, cooled, and centrifuged. The precipitate was washed, freeze-dried, and calcined to obtain g-C3N4 / TiO2 composite nanoparticles.

[0011] S2. Disperse g-C3N4 / TiO2 composite nanoparticles in an ethanol solution, add melanin dispersion and mix well, adjust the pH of the system to a weakly alkaline range with an alkaline regulator to obtain a photocatalytic finishing solution;

[0012] S3. The aminated substrate pretreated with amination is immersed in the photocatalytic finishing solution for finishing to obtain a finished substrate with a photocatalytic functional layer loaded on it.

[0013] S4. Immerse the base fabric in a hydrophilic finishing solution, remove it after wetting, and then dry and heat it to crosslink and cure it to form a hydrophilic protective layer on the fiber surface, thus obtaining a photocatalytic self-cleaning antibacterial fabric.

[0014] In some embodiments of the present invention, in step S1, the feeding ratio of g-C3N4 powder, anhydrous ethanol, tetrabutyl titanate and deionized water is (0.2-0.4) g:(40-60) mL:(1-3) mL:(1-3) mL.

[0015] In some embodiments of the present invention, in step S1, the hydrothermal reaction temperature is 120-180 °C and the reaction time is 6-12 h.

[0016] In some embodiments of the present invention, in step S1, the calcination temperature is 350-360 °C.

[0017] In some embodiments of the present invention, in step S2, the melanin dispersion is prepared by: dialysis purification of fresh squid ink, removing the molecular weight cutoff of 10-50 kDa, collecting the liquid in the dialysis bag, and filtering it with a filter membrane to obtain the melanin dispersion. The pore size of the filter membrane is preferably 0.22-0.45 μm.

[0018] In some embodiments of the present invention, in step S2, the final concentration of g-C3N4 / TiO2 composite nanoparticles in the photocatalytic finishing solution is 0.8-1.5 g / L, and the volume ratio of the melanin dispersion is 5-10 v / v.

[0019] In some embodiments of the present invention, in step S2, the alkalinity regulator is ammonia water, preferably 1-5 wt% ammonia water.

[0020] In some embodiments of the present invention, step S3 specifically involves:

[0021] Anhydrous ethanol and deionized water were mixed, and the pH was adjusted to 4.0-5.0. Then, 3-aminopropyltriethoxysilane was added to obtain an amination treatment solution. The base fabric, which had been washed and dried sequentially with deionized water and ethanol, was immersed in the amination treatment solution and reacted with shaking at room temperature for 2-4 hours. After removal, it was dried at 105±5 °C to obtain the amination base fabric. Anhydrous ethanol and deionized water were preferably mixed at a volume ratio of 85:15.

[0022] In some embodiments of the present invention, step S3 specifically involves: immersing the aminated base fabric in an impregnation bath ratio of 20:1-30:1, performing two dips and two nips, with a nip rate of 85%-90%, and then removing it and allowing it to drain naturally to obtain the finished base fabric.

[0023] In some embodiments of the present invention, in step S4, the hydrophilic finishing solution is prepared by 2 wt% polyvinyl alcohol aqueous solution and 25 wt% glutaraldehyde aqueous solution, and the volume ratio of polyvinyl alcohol aqueous solution to glutaraldehyde aqueous solution is 100 ml:(0.32-0.64) ml.

[0024] In some embodiments of the present invention, in step S4, the bath ratio of immersing the base fabric in the hydrophilic finishing solution is 20:1-30:1; the drying is carried out at 60-70 °C for 30-40 min; and the heating crosslinking and curing is carried out at 80-85 °C for 30-40 min.

[0025] In a second aspect, the present invention provides a photocatalytic self-cleaning antibacterial fabric prepared by the above-described preparation method.

[0026] Compared with existing technologies, the g-C3N4 / TiO2 / melanin ternary light-harvesting system constructed in this invention achieves highly efficient and stable photocatalytic self-cleaning and antibacterial functions through multiple synergistic mechanisms. First, melanin, as a natural light antenna, captures ultraviolet to near-infrared light energy with its broad-spectrum absorption characteristics and transfers it to g-C3N4 and TiO2 via sensitization, significantly broadening the spectral response range of the material. Second, the synergistic effect of the type II heterojunction formed by g-C3N4 / TiO2 and the "electron bridge" formed by the functional groups of melanin spatially separates photogenerated carriers while reducing interfacial transport resistance, effectively suppressing electron-hole recombination and significantly increasing the efficiency of reactive oxygen species (·OH, ·O2). -The high efficiency of free radical generation; these highly active free radicals can non-selectively oxidize and decompose organic stains such as grease and pigments attached to the fabric surface, breaking them down into small molecule products such as CO2 and H2O, while destroying bacterial cell membranes and viral protein structures, achieving broad-spectrum inactivation; in addition, the hydrophilic functional groups rich in melanin form a chemical bond network with the surface of silanized fibers, which not only firmly anchors the catalyst but also endows the interface with excellent hydrophilicity, so that the residues after photocatalytic degradation can be effectively wetted by water droplets and quickly carried away from the surface, avoiding secondary deposition and forming a self-cleaning closed loop of "decomposition-decontamination"; this design solves the core problems of narrow light response, fast charge recombination and weak interface adhesion of single materials, while achieving the synergy of continuous antibacterial and efficient self-cleaning functions in low light environment. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating the structure and mechanism of photocatalytic self-cleaning antibacterial fabric provided in an embodiment of the present invention.

[0028] Figure 2 Here is a high-resolution scanning electron microscope image of the fabric surface obtained in Example 1;

[0029] Figure 3 The graphs show the degradation ability of the fabrics in Examples 1-3 and Comparative Examples 1-3 to methylene blue under light and dark conditions.

[0030] Figure 4 The photocatalytic activity and antibacterial retention rate of the fabrics in Examples 1-3 and Comparative Examples 2-3 were measured 8 hours after 10, 30, and 50 washes. A represents the effect of the number of washes on the photocatalytic activity retention rate, B represents the effect of the number of washes on the antibacterial retention rate of Staphylococcus aureus on the fabric, and C represents the effect of the number of washes on the antibacterial retention rate of Escherichia coli on the fabric. Detailed Implementation

[0031] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0032] An embodiment of the first aspect of the present invention provides a method for preparing a photocatalytic self-cleaning antibacterial fabric, the method comprising the following steps:

[0033] S1. G-C3N4 powder was ultrasonically dispersed in anhydrous ethanol. Tetrabutyl titanate was slowly added dropwise under ice bath stirring, followed by the addition of deionized water and stirring to form a sol. The sol was then subjected to hydrothermal treatment, cooled, and centrifuged. The precipitate was washed, freeze-dried, and calcined to obtain g-C3N4 / TiO2 composite nanoparticles.

[0034] S2. Disperse g-C3N4 / TiO2 composite nanoparticles in an ethanol solution, add melanin dispersion and mix evenly, adjust the pH of the system to a weakly alkaline range with an alkaline regulator to obtain a photocatalytic finishing solution; preferably, use 95wt% ethanol for the ethanol solution.

[0035] S3. The aminated substrate pretreated with amination is immersed in the photocatalytic finishing solution for finishing to obtain a finished substrate with a photocatalytic functional layer loaded on it.

[0036] S4. Immerse the base fabric in a hydrophilic finishing solution, remove it after wetting, and then dry and heat it to crosslink and cure it to form a hydrophilic protective layer on the fiber surface, thus obtaining a photocatalytic self-cleaning antibacterial fabric.

[0037] A schematic diagram of the structure and mechanism of action of the photocatalytic self-cleaning antibacterial fabric is shown below. Figure 1 As shown. Figure 1 As shown, the present invention constructs a three-in-one photocatalytic functional structure with textile fiber (pure cotton or polyester-cotton blended fabric) as the substrate, a silane coupling layer (APTES) sequentially assembled on the surface, a photocatalytic functional layer composed of g-C3N4 / TiO2 heterojunction and melanin sensitization layer, and covered with a PVA protective layer.

[0038] On the one hand, melanin, as a natural biological pigment, possesses a semiconductor-like amorphous structure, enabling it to absorb sunlight across the entire wavelength range from ultraviolet to near-infrared under optimized proportions. This "antenna" effect effectively compensates for the limitations of TiO2, which only responds to ultraviolet light, and the insufficient absorption of long-wavelength visible light by g-C3N4 / TiO2. Under illumination, melanin not only generates photogenerated carriers but also acts as a photosensitizer, efficiently transferring absorbed energy to g-C3N4 / TiO2 and TiO2, significantly broadening the photoresponse range of the composite material. This synergistic effect improves the photon utilization rate of the fabric in low-light environments such as indoor lighting and early morning / evening, and achieves continuous antibacterial and self-cleaning functions through a cumulative effect, breaking through the dependence of traditional materials on strong ultraviolet light.

[0039] Secondly, this invention combines g-C3N4 / TiO2 with TiO2 to form a heterojunction interface. Under light, both materials generate electrons and holes, but in a single material, electrons and holes recombine rapidly, leading to energy waste. The heterostructure creates a built-in electric field at the interface, which automatically pushes electrons towards TiO2 and holes towards g-C3N4, spatially separating electrons and holes and greatly reducing the recombination probability. Simultaneously, the phenolic hydroxyl and carboxyl functional groups abundant in melanin molecules act as "electron bridges," helping electrons jump rapidly between different materials, further reducing transport obstacles. This dual separation mechanism significantly extends the survival time of electrons and holes, giving them more opportunities to react with water and oxygen in the air, generating highly oxidizing reactive oxygen species (such as hydroxyl radicals ·OH and superoxide anions ·O2). - This allows the fabric to effectively kill bacteria and decompose organic stains. Even in indoor lighting or low-light conditions in the morning or evening, the fabric continues to exert its antibacterial and self-cleaning functions through a long-term cumulative effect.

[0040] Thirdly, to address the issue of photocatalyst immobilization stability on fiber surfaces, this invention fully utilizes the multiple chemical interactions between melanin, fiber, and catalyst during the preparation process to achieve multiple chemical bonds. First, the fiber surface is aminated using APTES silane coupling agent to introduce active reaction sites. Second, the abundant phenolic hydroxyl and carboxyl functional groups in the melanin structure can not only form hydrogen bonds or covalent bonds (such as amide bonds) with the aminated fiber, but also undergo strong coordination and chemisorption with metal ions or hydroxyl groups on the g-C3N4 / TiO2 surface. The resulting "fiber-silane-melanin-catalyst" chemical bond network firmly anchors the functional layer to the fiber surface, rather than through simple physical adhesion.

[0041] Fourthly, the PVA layer forms a dense and continuous coating film on the fiber surface after being cross-linked with glutaraldehyde, effectively "locking" the g-C3N4 / TiO2 composite nanoparticles on the fiber surface. This avoids the functional layer from falling off due to mechanical friction and water flow shearing during washing, further improving the structural stability of the photocatalytic layer. At the same time, the hydrophilicity of the coating film enables the automatic removal of degraded stains with water.

[0042] Example 1

[0043] A photocatalytic self-cleaning antibacterial fabric is prepared by the following steps:

[0044] 1. Take 0.3 g g-C3N4 powder and add it to 50 mL of anhydrous ethanol. Disperse it by ultrasonication to form a uniform suspension. Under ice bath and vigorous stirring, slowly add 2 mL of tetrabutyl titanate (TBOT) to the suspension. Continue stirring after the addition is complete. Add 2 mL of deionized water and stir to obtain a sol. Transfer the sol to a polytetrafluoroethylene reactor and hydrothermally react at 150 °C for 9 h. After naturally cooling to room temperature, centrifuge, wash the precipitate with water, freeze-dry it into powder, and calcine it at 355±5 °C to obtain g-C3N4 / TiO2 composite nanoparticles.

[0045] 2. Fresh squid ink was purified by dialysis, with a molecular weight cutoff of 25 kDa. The liquid in the dialysis bag was collected and filtered through a 0.22 μm filter membrane to obtain a melanin dispersion.

[0046] 3. Mix anhydrous ethanol and deionized water at a volume ratio of 85:15, pre-adjust the pH to 4.5 with glacial acetic acid, and then add 3-aminopropyltriethoxysilane to make the final concentration of 3-aminopropyltriethoxysilane 1.0 wt% to obtain an amination treatment solution. After stirring for 5 min, add pure cotton base fabric that has been washed and dried sequentially with deionized water and ethanol at a bath ratio of 25:1, and shake at room temperature for 2 h. After removal, dry at 105±5 °C to obtain the amination base fabric.

[0047] 4. Add g-C3N4 / TiO2 composite nanoparticles to 95 wt% ethanol and mix with melanin dispersion to achieve a final concentration of 1.1 g / L for the g-C3N4 / TiO2 nanoparticles and a volume percentage of 8% (v / v) for the melanin dispersion. After ultrasonic dispersion, adjust the pH to 8.5 with 2 wt% ammonia. Then immerse the aminated base fabric in the mixture at an impregnation bath ratio of 25:1. Perform two dips and two nips, with a nip residue of 88%. Remove the fabric and allow it to drain naturally to obtain the finished base fabric.

[0048] 5. Prepare a 2 wt% polyvinyl alcohol (weight average molecular weight 85000) solution. Add 0.48 mL of 25 wt% glutaraldehyde aqueous solution to every 100 mL of polyvinyl alcohol solution. After stirring, immediately immerse the base fabric in the solution at a bath ratio of 25:1. Let it stand for 25 seconds, then remove it and dry it at 65 °C for 30 min, followed by crosslinking at 82 °C for 30 min. This yields the photocatalytic self-cleaning antibacterial fabric. The scanning electron microscope image is shown below. Figure 2 As shown, PVA is coated on the outer surface of the complex of melanin and g-C3N4 / TiO2 particles.

[0049] Example 2

[0050] A photocatalytic self-cleaning antibacterial fabric is prepared by the following steps:

[0051] 1. Take 0.2 g g-C3N4 powder and add it to 40 mL of anhydrous ethanol. Disperse it by ultrasonication to form a uniform suspension. Under ice bath and vigorous stirring, slowly add 1 mL tetrabutyl titanate (TBOT) to the suspension. Continue stirring after the addition is complete. Add 1 mL of deionized water and stir to obtain a sol. Transfer the sol to a polytetrafluoroethylene reactor and hydrothermally react at 120 °C for 12 h. After naturally cooling to room temperature, centrifuge, wash the precipitate with water, freeze dry it to obtain powder, and calcine at 355±5 °C to obtain g-C3N4 / TiO2 composite nanoparticles.

[0052] 2. Fresh squid ink was purified by dialysis, with a molecular weight cutoff of 10 kDa. The liquid in the dialysis bag was collected and filtered through a 0.22 μm filter membrane to obtain a melanin dispersion.

[0053] 3. Mix anhydrous ethanol and deionized water at a volume ratio of 85:15, pre-adjust the pH to 4.0 with glacial acetic acid, and then add 3-aminopropyltriethoxysilane to make the final concentration of 3-aminopropyltriethoxysilane 0.5 wt% to obtain an amination treatment solution. After stirring for 5 min, add a polyester-cotton blended base fabric that has been washed and dried sequentially with deionized water and ethanol at a liquor ratio of 20:1, and shake at room temperature for 2 h. After removal, dry at 105±5 °C to obtain the amination base fabric.

[0054] 4. Add g-C3N4 / TiO2 composite nanoparticles to 95 wt% ethanol and mix with melanin dispersion to achieve a final concentration of 0.8 g / L for the g-C3N4 / TiO2 nanoparticles and a volume percentage of 5% (v / v) for the melanin dispersion. After ultrasonic dispersion, adjust the pH to 8.3 with 1 wt% ammonia. Then immerse the aminated base fabric in the mixture at an impregnation bath ratio of 20:1. Perform two dips and two nips, with a nip residue of 85%. Remove the fabric and allow it to drain naturally to obtain the finished base fabric.

[0055] 5. Prepare a 2 wt% polyvinyl alcohol (weight average molecular weight of 85,000) solution. Add 0.32 mL of 25 wt% glutaraldehyde aqueous solution to every 100 mL of polyvinyl alcohol solution. After stirring, immediately immerse the base fabric in the solution at a bath ratio of 20:1. Let it stand for 20 seconds, then remove it and dry it at 60 °C for 30 min. Then crosslink it at 80 °C for 30 min to obtain the photocatalytic self-cleaning antibacterial fabric.

[0056] Example 3

[0057] A photocatalytic self-cleaning antibacterial fabric is prepared by the following steps:

[0058] 1. Take 0.4 g g-C3N4 powder and add it to 60 mL of anhydrous ethanol. Disperse it by ultrasonication to form a uniform suspension. Under ice bath and vigorous stirring, slowly add 3 mL of tetrabutyl titanate (TBOT) to the suspension. Continue stirring after the addition is complete. Then add 3 mL of deionized water and stir to obtain a sol. Transfer the sol to a polytetrafluoroethylene reactor and hydrothermally react at 180 °C for 6 h. After naturally cooling to room temperature, centrifuge, wash the precipitate with water, freeze dry it to obtain powder, and calcine at 355±5 °C to obtain g-C3N4 / TiO2 composite nanoparticles.

[0059] 2. Fresh squid ink was purified by dialysis, with a molecular weight cutoff of 50 kDa. The liquid in the dialysis bag was collected and filtered through a 0.22 μm filter membrane to obtain a melanin dispersion.

[0060] 3. Mix anhydrous ethanol and deionized water at a volume ratio of 85:15, pre-adjust the pH to 5.0 with glacial acetic acid, and then add 3-aminopropyltriethoxysilane to make the final concentration of 3-aminopropyltriethoxysilane 2.0 wt% to obtain an amination treatment solution. After stirring for 5 min, add pure cotton base fabric that has been washed and dried sequentially with deionized water and ethanol at a bath ratio of 30:1, and shake at room temperature for 2 h. After removal, dry at 105±5 °C to obtain the amination base fabric.

[0061] 4. Add g-C3N4 / TiO2 composite nanoparticles to 95 wt% ethanol and mix with melanin dispersion to achieve a final concentration of 1.5 g / L for the g-C3N4 / TiO2 nanoparticles and a volume percentage of 10% (v / v) for the melanin dispersion. After ultrasonic dispersion, adjust the pH to 8.7 with 5 wt% ammonia. Then immerse the aminated base fabric in the mixture at an impregnation bath ratio of 30:1. Perform two dips and two nips, with a nip-out rate of 90%. Remove the fabric and allow it to drain naturally to obtain the finished base fabric.

[0062] 5. Prepare a 2 wt% polyvinyl alcohol (weight average molecular weight of 85,000) solution. Add 0.64 mL of 25 wt% glutaraldehyde aqueous solution to every 100 mL of polyvinyl alcohol solution. After stirring, immediately immerse the base fabric in the solution at a bath ratio of 30:1. Let it stand for 30 seconds, remove it, dry it at 70 °C for 30 minutes, and then crosslink it at 85 °C for 30 minutes to obtain the photocatalytic self-cleaning antibacterial fabric.

[0063] Comparative Example 1 (without g-C3N4 / TiO2 heterojunction nanocomposite layer)

[0064] A method for preparing a fabric includes the following steps:

[0065] 1. Fresh squid ink was purified by dialysis, with a molecular weight cutoff of 25 kDa. The liquid in the dialysis bag was collected and filtered through a 0.22 μm filter membrane to obtain a melanin dispersion.

[0066] 2. Anhydrous ethanol and deionized water were mixed at a volume ratio of 85:15. The pH was pre-adjusted to 4.5 with glacial acetic acid. Then, 3-aminopropyltriethoxysilane was added to make the final concentration of 3-aminopropyltriethoxysilane 1.0 wt%, which yielded an amination treatment solution. After stirring for 5 min, pure cotton base fabric that had been washed and dried sequentially with deionized water and ethanol was added. The bath ratio was 25:1. The reaction was carried out at room temperature with shaking for 2 h. After removal, the mixture was dried at 105±5 °C to obtain the amination base fabric.

[0067] 3. Mix 95 wt% ethanol with the melanin dispersion to achieve a melanin dispersion volume ratio of 8% (v / v). After ultrasonic dispersion, adjust the pH to 8.5 with 2 wt% ammonia. Then immerse the aminated base fabric in the mixture at an impregnation bath ratio of 25:1. Perform two dips and two nips, with a nip rate of 88%. Remove the fabric and allow it to drain naturally to obtain the finished base fabric.

[0068] 4. Prepare a 2 wt% polyvinyl alcohol (weight average molecular weight of 85,000) solution. Add 0.48 mL of 25 wt% glutaraldehyde aqueous solution to every 100 mL of polyvinyl alcohol solution. After stirring, immediately immerse the base fabric in the solution at a liquor ratio of 25:1. Let it stand for 25 seconds, then remove it and dry it at 65 °C for 30 minutes. Then crosslink it at 82 °C for 30 minutes to obtain the fabric.

[0069] Comparative Example 2 (without melanin)

[0070] A method for preparing a fabric includes the following steps:

[0071] 1. Take 0.3 g g-C3N4 powder and add it to 50 mL of anhydrous ethanol. Disperse it by ultrasonication to form a uniform suspension. Under ice bath and vigorous stirring, slowly add 2 mL of tetrabutyl titanate (TBOT) to the suspension. Continue stirring after the addition is complete. Add 2 mL of deionized water and stir to obtain a sol. Transfer the sol to a polytetrafluoroethylene reactor and hydrothermally react at 150 °C for 9 h. After naturally cooling to room temperature, centrifuge, wash the precipitate with water, freeze-dry it into powder, and calcine it at 355±5 °C to obtain g-C3N4 / TiO2 composite nanoparticles.

[0072] 2. Anhydrous ethanol and deionized water were mixed at a volume ratio of 85:15. The pH was pre-adjusted to 4.5 with glacial acetic acid. Then, 3-aminopropyltriethoxysilane was added to make the final concentration of 3-aminopropyltriethoxysilane 1.0 wt%, which yielded an amination treatment solution. After stirring for 5 min, pure cotton base fabric that had been washed and dried sequentially with deionized water and ethanol was added. The bath ratio was 25:1. The reaction was carried out at room temperature with shaking for 2 h. After removal, the mixture was dried at 105±5 °C to obtain the amination base fabric.

[0073] 3. Add g-C3N4 / TiO2 composite nanoparticles to 95 wt% ethanol to achieve a final concentration of 1.1 g / L. After ultrasonic dispersion, adjust the pH to 8.5 with 2 wt% ammonia. Then immerse the aminated base fabric in the solution at an impregnation bath ratio of 25:1. Perform two dips and two nips, with a nip rate of 88%. Remove the fabric and allow it to drain naturally to obtain the finished base fabric.

[0074] 4. Prepare a 2 wt% polyvinyl alcohol (weight average molecular weight of 85,000) solution. Add 0.48 mL of 25 wt% glutaraldehyde aqueous solution to every 100 mL of polyvinyl alcohol solution. After stirring, immediately immerse the base fabric in the solution at a liquor ratio of 25:1. Let it stand for 25 seconds, then remove it and dry it at 65 °C for 30 minutes. Then crosslink it at 82 °C for 30 minutes to obtain the fabric.

[0075] Comparative Example 3 (without protective layer)

[0076] A method for preparing a fabric includes the following steps:

[0077] 1. Take 0.3 g g-C3N4 powder and add it to 50 mL of anhydrous ethanol. Disperse it by ultrasonication to form a uniform suspension. Under ice bath and vigorous stirring, slowly add 2 mL of tetrabutyl titanate (TBOT) to the suspension. Continue stirring after the addition is complete. Add 2 mL of deionized water and stir to obtain a sol. Transfer the sol to a polytetrafluoroethylene reactor and hydrothermally react at 150 °C for 9 h. After naturally cooling to room temperature, centrifuge, wash the precipitate with water, freeze-dry it into powder, and calcine it at 355±5 °C to obtain g-C3N4 / TiO2 composite nanoparticles.

[0078] 2. Fresh squid ink was purified by dialysis, with a molecular weight cutoff of 25 kDa. The liquid in the dialysis bag was collected and filtered through a 0.22 μm filter membrane to obtain a melanin dispersion.

[0079] 3. Mix anhydrous ethanol and deionized water at a volume ratio of 85:15, pre-adjust the pH to 4.5 with glacial acetic acid, and then add 3-aminopropyltriethoxysilane to make the final concentration of 3-aminopropyltriethoxysilane 1.0 wt% to obtain an amination treatment solution. After stirring for 5 min, add pure cotton base fabric that has been washed and dried sequentially with deionized water and ethanol at a bath ratio of 25:1, and shake at room temperature for 2 h. After removal, dry at 105±5 °C to obtain the amination base fabric.

[0080] 4. Add g-C3N4 / TiO2 composite nanoparticles to 95 wt% ethanol and mix with melanin dispersion to achieve a final concentration of 1.1 g / L for the g-C3N4 / TiO2 nanoparticles and a volume percentage of 8% (v / v) for the melanin dispersion. After ultrasonic dispersion, adjust the pH to 8.5 with 2 wt% ammonia. Then immerse the aminated base fabric in the mixture at a bath ratio of 25:1. Perform two dips and two nips, with a nip rate of 88%. After removal, dry at 65 °C for 30 min, and then at 82 °C for 30 min to obtain the fabric.

[0081] Test Example 1: Photocatalytic Activity Test

[0082] Method: Fabric samples from Examples 1-3 and Comparative Examples 1-3 were cut into 2 cm x 2 cm pieces, placed in 20 mL of 10 mg / L methylene blue aqueous solution, shaken in the dark for 30 min, and then placed under simulated sunlight at 100 mW / cm². 2 Under xenon lamp irradiation, the fabric sample was photographed and its K / S value measured every 2 hours using the Digieye colorimetric system. The total test duration was 8 hours. The fabric's ability to decompose organic matter was calculated using the following formula, and the results are as follows: Figure 3 As shown.

[0083]

[0084] In the formula, η represents the rate of decrease of K / S, K / S0 is the K / S value of the fabric before light exposure, and K / S t This indicates the K / S value of the fabric after exposure to light; the larger the value of η, the better the self-cleaning effect of the fabric.

[0085] according to Figure 3 The test results showed that the fabrics in Examples 1-3 exhibited a degradation rate (K / S reduction rate) of over 90% (up to 95.56%) for methylene blue after 8 hours of simulated sunlight exposure, demonstrating excellent self-cleaning ability. In contrast, Comparative Example 1 (without photocatalyst) showed almost zero degradation, Comparative Example 2 (without melanin) only 37.51%, and Comparative Example 3 (without protective layer) showed high activity (92.62%). This significant difference indicates that the core reason the fabrics in the examples achieve high self-cleaning efficiency lies in the construction of a ternary synergistic system of "g-C3N4 / TiO2 heterojunction + melanin," in which melanin plays a crucial role. Comparative Example 2, lacking melanin, has a limited light absorption range and low charge separation efficiency, resulting in a catalytic efficiency under visible light that is less than half that of the examples. Furthermore, the design of the hydrophilic protective layer can increase the degradation rate of pollutants such as methylene blue.

[0086] Test Example 2: Antibacterial Performance Test

[0087] Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 8739 were selected as representative Gram-positive and Gram-negative bacterial strains, respectively. The antimicrobial properties of the fabrics in Examples 1-3 and Comparative Examples 1-3 were tested under simulated daylight xenon lamp irradiation (100 mW / cm²) using GB / T 20944.3-2008, "Evaluation of antimicrobial properties of textiles - Part 3: Shaking method". 2 (and its antibacterial properties under light-protected conditions.)

[0088] Table 1. Antibacterial rate of various fabrics determined by the oscillation method.

[0089]

[0090] The antibacterial test results showed that the fabrics in Examples 1-3 and Comparative Example 3 exhibited strong antibacterial effects against Staphylococcus aureus and Escherichia coli only under light irradiation. However, the antibacterial effect of Comparative Example 2 fabric was significantly weakened under light irradiation, and Comparative Example 1 fabric showed no significant antibacterial effect. The reason for this is that under light irradiation, the g-C3N4 / TiO2 heterojunction in Examples 1-3, Comparative Example 2, and Comparative Example 3 can photocatalyze the generation of reactive oxygen species (ROS), which is the core of the bactericidal effect. Furthermore, Examples 1-3 and Comparative Example 3 also incorporated melanin, which improved electron transfer efficiency, reduced transport obstacles, and prolonged the survival time of electrons and holes, thus better maintaining a highly reactive ORS environment on the fabric surface, resulting in significantly higher bactericidal efficiency than Comparative Example 2 (without melanin).

[0091] Test Example 3: Wash Resistance Test

[0092] According to the requirements of GB / T 8629-2017 "Home Washing and Drying Procedures for Textile Testing", the fabric samples of Examples 1-3 and Comparative Examples 2-3 were subjected to standard home washing for 10, 30, and 50 cycles. Afterwards, the fabrics were tested under simulated daylight xenon lamp irradiation (100 mW / cm²) according to the methods in Test Example 1 and Test Example 2, respectively. 2 The photocatalytic activity and antibacterial rate under the following conditions for 8 hours were calculated using the following formulas: [Results are shown in the original text]. Figure 4 As shown.

[0093]

[0094] In the formula, V0 represents the initial photocatalytic activity or antibacterial rate, and V represents the photocatalytic activity or antibacterial rate after washing.

[0095] like Figure 4As shown, with increasing washing cycles, the performance of all fabrics decreased to varying degrees, but the performance retention rates of Examples 1-3 were significantly better than those of Comparative Examples 2 and 3. For example, after 50 washes, the photocatalytic activity retention rate of Examples 1-3 remained above 60%, while the activity retention rates of Comparative Examples 2 (without melanin) and 3 (without a PVA protective layer) both decreased to below 10%. Similarly, in terms of antibacterial performance, Examples 1-3 maintained antibacterial retention rates of over 85% against Staphylococcus aureus and Escherichia coli, while the antibacterial retention rates of Comparative Examples 2 and 3 decreased significantly. Especially after 50 washes, the antibacterial retention rates against Staphylococcus aureus decreased to below 40% and 15%, respectively, and against Escherichia coli, respectively, failing to meet the requirements for long-lasting antibacterial effects.

[0096] The above results demonstrate that the multilayer composite structure constructed in this invention plays a crucial role in improving the wash resistance of fabrics. In contrast, Comparative Example 2, lacking the chemical bridging effect of melanin, cannot achieve long-term anchoring solely through PVA coating; Comparative Example 3, lacking a PVA protective layer, has photocatalytic particles directly exposed to the washing environment, making them more prone to detachment and leading to rapid performance degradation.

[0097] This invention provides a photocatalytic self-cleaning antibacterial fabric and its preparation method. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing a photocatalytic self-cleaning antibacterial fabric, characterized in that, The preparation method includes the following steps: S1. G-C3N4 powder was ultrasonically dispersed in anhydrous ethanol. Tetrabutyl titanate was slowly added dropwise under ice bath stirring, followed by the addition of deionized water and stirring to form a sol. The sol was then subjected to hydrothermal treatment, cooled, and centrifuged. The precipitate was washed, freeze-dried, and calcined to obtain g-C3N4 / TiO2 composite nanoparticles. S2. Disperse g-C3N4 / TiO2 composite nanoparticles in an ethanol solution, add melanin dispersion and mix well, adjust the pH of the system to a weakly alkaline range with an alkaline regulator to obtain a photocatalytic finishing solution; S3. The aminated substrate pretreated with amination is immersed in the photocatalytic finishing solution for finishing to obtain a finished substrate with a photocatalytic functional layer loaded on it. S4. Immerse the base fabric in a hydrophilic finishing solution, remove it after wetting, and then dry and heat it to crosslink and cure it to form a hydrophilic protective layer on the fiber surface, thus obtaining a photocatalytic self-cleaning antibacterial fabric.

2. The preparation method according to claim 1, characterized in that, In step S1, the feeding ratio of g-C3N4 powder, anhydrous ethanol, tetrabutyl titanate and deionized water is (0.2-0.4) g:(40-60) mL:(1-3) mL:(1-3) mL.

3. The preparation method according to claim 1, characterized in that, In step S1, the hydrothermal treatment reaction temperature is 120-180 °C and the reaction time is 6-12 h.

4. The preparation method according to claim 1, characterized in that, In step S2, the melanin dispersion is prepared by: dialysis purification of fresh squid ink, with a molecular weight cutoff of 10-50 kDa, collecting the liquid in the dialysis bag, filtering with a filter membrane to obtain the melanin dispersion.

5. The preparation method according to claim 1, characterized in that, In step S2, the final concentration of g-C3N4 / TiO2 composite nanoparticles in the photocatalytic finishing solution is 0.8-1.5 g / L, and the volume ratio of the melanin dispersion is 5-10 v / v.

6. The preparation method according to claim 1, characterized in that, In step S3, the amination pretreatment specifically includes: Anhydrous ethanol and deionized water were mixed, and the pH was adjusted to 4.0-5.

0. Then, 3-aminopropyltriethoxysilane was added to obtain the amination treatment solution. The base fabric, which has been washed and dried sequentially with deionized water and ethanol, is immersed in the amination treatment solution and reacted with shaking at room temperature for 2-4 hours. After removal, it is dried to obtain the amination base fabric.

7. The preparation method according to claim 1, characterized in that, In step S3, the finishing process specifically involves immersing the aminated base fabric in an impregnation bath ratio of 20:1-30:1, performing two dips and two nips, with a nip rate of 85-90%, and then removing it and allowing it to drain naturally to obtain the finished base fabric.

8. The preparation method according to claim 1, characterized in that, In step S4, the hydrophilic finishing solution is prepared by mixing 2 wt% polyvinyl alcohol aqueous solution and 25 wt% glutaraldehyde aqueous solution, with a volume ratio of 100 ml:(0.32-0.64) ml.

9. The preparation method according to claim 1, characterized in that, In step S4, the bath ratio of immersing the base fabric in the hydrophilic finishing solution is 20:1-30:1; the drying process specifically involves drying at 60-70 °C for 30-40 min; and the heating crosslinking and curing process involves heating at 80-85 °C for 30-40 min.

10. The photocatalytic self-cleaning antibacterial fabric prepared by the preparation method according to any one of claims 1-9.

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