Preparation and application of high-adhesion nano-TiO2 photocatalytic coating

Abstract

The application discloses a high-adhesion nano-TiO2 photocatalytic coating and a preparation method thereof. First, nano-TiO2 particles are prepared, and a loading base material is pretreated; then, a TiO2 coating hydrosol is prepared by using a silicon sol modification; the hydrosol is ultrasonically dispersed, and a coating film is prepared on the pretreated base material; finally, the film is gradually heated and dried in a heat treatment device, and finally, the high-adhesion TiO2 photocatalytic coating is obtained. The TiO2 photocatalytic coating has superior photocatalytic performance, strong adhesion of the coating film, and is not easy to fall off, can effectively remove residual VOCs and NH3 pollutants in an atmospheric environment, and has excellent economy and practicability.

Description

Technical Field

[0001] This invention relates to a highly adhesive nano-TiO2 photocatalytic coating, as well as the preparation method of the photocatalytic coating and its specific application in the treatment of air pollutants, belonging to the field of air pollutant treatment technology. Background Technology

[0002] With the rapid advancement of socio-economic development and urbanization, urban environmental pollution and its prevention and control have increasingly attracted widespread attention. The number of gasoline-powered vehicles has increased dramatically, emitting large amounts of pollutants in their exhaust, severely polluting the atmospheric environment. Simultaneously, substandard building materials release harmful substances over long periods, causing significant indoor air pollution. These air pollutants can directly threaten the human respiratory system and endanger public health. Therefore, effectively controlling indoor and outdoor air pollution has become a research hotspot, leading to the development of various purification technologies. Among these, photocatalysis technology is highly favored due to its environmental friendliness and high purification efficiency. Among numerous photocatalysts, TiO2, with its high technological maturity and broad application prospects, has become one of the most promising materials in the field of environmental photocatalysis.

[0003] TiO2 is an n-type wide bandgap semiconductor material. When exposed to light energy greater than or equal to its bandgap, TiO2 is excited, and electrons in the valence band jump to the conduction band, simultaneously creating corresponding holes in the valence band. These photogenerated holes have strong oxidizing properties, while the electrons in the conduction band have strong reducing properties. Together, they construct a highly efficient redox system, which endows TiO2 with excellent photocatalytic activity.

[0004] TiO2 has attracted much attention in the field of environmental purification due to its advantages such as good stability, high photocatalytic activity, corrosion resistance, low cost, and non-toxicity. However, it still has some limitations: TiO2 catalysts with common morphologies have low quantum efficiency and high recombination rates of photogenerated electrons and holes, which limits the overall photocatalytic efficiency and restricts its further performance.

[0005] TiO2-based photocatalytic coatings demonstrate broad application prospects due to their ability to efficiently degrade VOCs (volatile organic compounds) and nitrogen oxides in the air using light energy. Traditional processes that directly mix TiO2 with the coating have significant problems: the coating base material used coats the TiO2 particles – this coating significantly reduces the effective light-receiving ratio of TiO2, leading to a decrease in the generation efficiency of photogenerated electron-hole pairs, thus significantly weakening its photodegradation ability.

[0006] Existing photocatalytic coatings generally have the following shortcomings: (1) Indoor / outdoor wall coating substrates are prone to encapsulating photocatalyst particles, which significantly reduces the catalytic effect of the photocatalyst.

[0007] (2) TiO2 photocatalysis has a weak ability to be excited by visible light, and its catalytic effect is very limited under indoor lighting.

[0008] Therefore, developing photocatalytic and environmentally friendly coatings with superior comprehensive performance has significant market value and environmental significance. Summary of the Invention

[0009] The primary technical problem to be solved by this invention is to provide a highly adhesive nano-TiO2 photocatalytic coating that can improve photocatalytic efficiency while ensuring anti-aging performance.

[0010] Another technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned photocatalytic coating.

[0011] Another technical problem to be solved by the present invention is to provide a method for applying the above-mentioned photocatalytic coating.

[0012] To achieve the above objectives, the present invention adopts the following technical solution: According to a first aspect of the present invention, a highly adhesive nano-TiO2 photocatalytic coating is provided, comprising the following components in parts by weight: 100 parts water; 5-20 parts TiO2 nanoparticles; 5-20 parts silica sol; 0.5-1 parts polydimethylsiloxane; 0.1-0.2 parts octylphenol polyoxyethylene ether; 0.1-0.2 parts polyether-modified silicone oil diluent, which is prepared by mixing polyether-modified silicone oil and propylene glycol in a 1:1 weight ratio; and 0.1-0.2 parts potassium chloride; wherein, The TiO2 nanoparticles are nanoparticles with exposed 001 crystal planes, and are prepared using the following method: Step 1. Take a 100mL beaker and add 50mL of tetrabutyl titanate; Step 2. Control the magnetic stirrer speed to 500-600 r / min, slowly add 6 mL of hydrofluoric acid to the beaker, and continue stirring for 2 hours; Step 3. Transfer the solid-liquid mixture obtained in Step 2 to a reaction vessel and react at 180°C for 24 hours. After the reaction is completed, perform vacuum filtration. Step 4. Dry the solid material obtained in Step 3 and grind it to a particle size of less than 50 nm to obtain nano-TiO2 nanoparticle powder.

[0013] According to a second aspect of the present invention, a method for preparing the above-mentioned highly adhesive nano-TiO2 photocatalytic coating is provided, comprising: 5-20 parts of TiO2 nanoparticles, 5-20 parts of silica sol, 0.5-1 parts of defoamer polydimethylsiloxane, 0.1-0.2 parts of octylphenol polyoxyethylene ether; 0.1-0.2 parts of polyether-modified silicone oil (TEGO-450) diluted with propylene glycol at a ratio of 1:1, and 0.1-0.2 parts of potassium chloride; and 100 parts of water. The above materials are gradually added, and the mixture is stirred at a speed of 300-800 r / min for at least 0.5 h. After all materials are added, the mixture is stirred at the same speed for another 1-2 h to obtain modified hydrosol TiO2. The modified hydrosol TiO2 was dispersed by ultrasonication and then coated onto the corresponding substrate by flat coating or spraying to obtain a composite film; after heating and drying, a highly adhesive TiO2 photocatalytic coating was obtained.

[0014] According to a third aspect of the present invention, a method for applying the above-mentioned highly adhesive nano-TiO2 photocatalytic coating is provided, wherein the modified hydrosol TiO2 is dispersed by ultrasonication for 15 minutes and then coated onto a polytetrafluoroethylene substrate in a flat coating manner to obtain a composite film; 1000-2000g of modified hydrosol TiO2 is used per square meter of substrate to prepare the coating. The composite film is placed in a drying oven and heated gradually from room temperature to 40℃-80℃ over 20 minutes, and maintained for 6-12 hours for drying treatment; finally, a highly adhesive TiO2 photocatalytic coating is obtained.

[0015] Furthermore, after dispersing the modified hydrosol TiO2 with ultrasound for 15 minutes, the coating is evenly sprayed onto the HEPA filter screen using an electric spray gun, ensuring that the screen thickness is above 0.02 mm. After drying, a highly adhesive TiO2 photocatalytic coating is obtained.

[0016] In this embodiment of the invention, silica sol is used in conjunction with nano-TiO2, which can improve the hardness, wear resistance, and scratch resistance of the coating, while also providing high-temperature resistance. The nano-silica particles in the silica sol can fill the gaps between the titanium dioxide particles and the resin, forming a dense inorganic-organic hybrid network; during film formation and curing, the silica sol particles undergo dehydration condensation to form Si-O-Si covalent bonds, which combine with the hydroxyl groups on the surface of titanium dioxide to construct a rigid framework, significantly improving the hardness, scratch resistance, and wear resistance of the coating.

[0017] The surfactant used in this invention not only improves the dispersibility and stability of titanium dioxide particles: the hydrolyzable groups (such as alkoxy groups) at one end of the surfactant molecule can undergo dehydration condensation with the hydroxyl groups on the surface of titanium dioxide particles to form strong covalent bonds; the organic functional groups (such as amino and vinyl groups) at the other end can interact with the coating resin molecules (compatibility or cross-linking). Therefore, an organic coating layer is formed on the surface of titanium dioxide particles, increasing the steric hindrance between particles, reducing particle agglomeration, maintaining the uniform dispersion of titanium dioxide in the coating system, and also enhancing the storage stability of the coating. The cross-linking properties of the surfactant can inhibit the sedimentation and flocculation of titanium dioxide particles throughout the entire storage process of the coating, while reducing abnormal viscosity fluctuations caused by particle aggregation; in addition, the interfacial chemical bonds formed can also reduce the erosion of the titanium dioxide particle surface by impurities such as moisture, delaying the delamination and deterioration of the coating.

[0018] During the preparation and stirring of high-adhesion nano-TiO2 photocatalytic coatings, air bubbles are easily trapped, leading to artificially high viscosity and poor leveling properties. Organosilicon defoamers can quickly break down the elastic membrane of air bubbles, reducing the bubble content in the system and enabling smoother brushing and spraying, thus reducing brush marks and sagging during application.

[0019] The aforementioned highly adhesive nano-TiO2 photocatalytic coating has active centers on its surface that can continuously dissociate oxygen molecules in the air into active single oxygen negative ions. At the same time, the catalytic coating adsorbs formaldehyde, a target pollutant. Under the action of active single oxygen negative ions, formaldehyde is completely oxidized and decomposed into carbon dioxide and water. Carbon dioxide and water desorb from the surface of the photocatalyst, releasing active sites to continuously oxidize formaldehyde, cyclically catalyze, and purify the air for a long time. Most of the formaldehyde is oxidized into carbon dioxide and water.

[0020] Traditional photocatalytic coatings suffer from significant drawbacks: the photocatalytic material is encapsulated within the coating, resulting in extremely low light exposure due to the coating's shielding effect, thus drastically reducing photocatalytic efficiency. To address this issue, this invention innovatively employs a surface coating process for the photocatalytic material, exposing active oxygen negative ions in situ to the coating surface. This allows the material to be fully exposed to light, significantly increasing the effective light-receiving area of ​​the photocatalytic material and thereby significantly enhancing its photocatalytic activity, achieving highly efficient photocatalytic decontamination. Simultaneously, this coating formulation incorporates a special silica sol as a functional enhancement component, effectively improving the coating's overall physical properties and endowing it with excellent hardness, wear resistance, scratch resistance, and high-temperature resistance. Compared to conventional photocatalytic coating materials, the coating prepared by this invention combines excellent physical protection properties with highly efficient photocatalytic degradation capabilities for gaseous pollutants. Taking nitrogen oxide degradation as an example, this coating can achieve highly efficient removal of nitrogen oxides under mild natural light conditions, and the entire process generates no secondary pollution, making it of significant research value and broad application prospects in fields such as atmospheric environmental governance.

[0021] Compared with the prior art, the beneficial effects of the present invention include: 1. The highly adhesive nano-TiO2 photocatalytic coating prepared by this invention can be directly coated onto the substrate surface, allowing the photocatalytic components to be fully exposed to the light environment, thereby significantly improving the photocatalytic performance of the material. Simultaneously, the silica sol introduced into the formulation effectively enhances the coating's hardness, wear resistance, and scratch resistance, greatly improving the overall durability of the coating. This coating material combines highly efficient photocatalytic activity with excellent physical protective properties, showing promising application prospects in the field of environmental remediation.

[0022] 2. The raw materials used in this invention are environmentally friendly, the synthesis process is simple and easy to operate, there is no harmful substance emission during the production process, energy consumption is low, production cost is low, and it is easy to produce on a large scale. Attached Figure Description

[0023] Figure 1 The XRD pattern of a highly adhesive nano-TiO2 photocatalytic coating with (001) crystal facets exposed.

[0024] Figure 2 Transmission electron microscope image of TiO2 nanosheets with (001) crystal planes exposed.

[0025] Figure 3 Transmission electron microscope image of TiO2 nanosheets with (001) crystal planes exposed.

[0026] Figure 4 Transmission electron microscope image of TiO2 nanosheets with (001) crystal planes exposed.

[0027] Figure 5 Transmission electron microscope image of TiO2 nanosheets with (001) crystal planes exposed to show lattice fringes.

[0028] Figure 6 This is the HAADF image of the TiO2 coating.

[0029] Figure 7 This is a diagram showing the silicon element distribution of the TiO2 coating.

[0030] Figure 8 This is a diagram showing the oxygen distribution of the TiO2 coating.

[0031] Figure 9 This is a diagram showing the titanium element distribution in the TiO2 coating.

[0032] Figure 10 This is a bar chart of the formaldehyde conversion rate-time curve of the highly adhesive nano-TiO2 photocatalytic coating with (001) crystal facets prepared in Example 3.

[0033] Figure 11 This is a bar chart showing the formaldehyde conversion rate-time curve of the highly adhesive nano-TiO2 photocatalytic coating with (001) crystal facets prepared in Example 3.

[0034] Figure 12 The bar chart shows the formaldehyde conversion rate-time of the TiO2 photocatalytic coating with (001) crystal facets prepared in Example 4.

[0035] Figure 13 The bar chart shows the formaldehyde conversion rate-time curve of the TiO2 photocatalytic coating with (001) crystal facets exposed prepared in Example 4.

[0036] Figure 14 The bar chart shows the formaldehyde conversion rate-time of the TiO2 photocatalytic coating with (001) crystal facets exposed prepared in Example 5.

[0037] Figure 15 The image shows a comparison of the TiO2 photocatalytic coating with (001) crystal plane exposure prepared in Example 6 before and after ammonia purification.

[0038] Figure 16 The adhesion grade test diagram of the TiO2 photocatalytic coating with (001) crystal facets exposed prepared in Example 7.

[0039] Figure 17 The Raman spectrum of TiO2 with (001) crystal plane exposure prepared in Example 1. Detailed Implementation

[0040] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] Example 1: Preparation of TiO2 nanoparticles with (001) crystal plane exposure features Step 1: Take a clean and dry 100mL beaker, put in a magnetic stir bar, place it on a magnetic stirrer, and use a 100mL graduated cylinder to measure 50mL of tetrabutyl titanate and pour it into the beaker.

[0043] Step 2: Control the magnetic stirrer speed to 500-600 r / min, use a 10mL syringe to slowly add 6mL of hydrofluoric acid into the beaker, and continue stirring for 2 hours.

[0044] Step 3: Transfer the solid-liquid mixture from the beaker in Step 2 to a high-pressure reactor with a polytetrafluoroethylene liner, and react at 180°C for 24 hours. After the reaction is complete, filter the mixture and wash the prepared solid three times with 150 mL of anhydrous ethanol.

[0045] Step 4: Place the solid material prepared in step 3 in a 70°C oven and dry for 2 hours. Grind it until the particle size is below 50nm to obtain nano-TiO2 nanoparticle powder.

[0046] like Figure 17 The image shows the Raman spectrum of TiO2 with exposed (001) crystal planes. The titanium dioxide prepared by the above method consists of titanium dioxide nanoparticles with exposed (001) crystal planes and a particle size of 20-30 nm. It retains the crystal structure integrity of the anatase phase. The photocatalytic coating prepared in this way has lattice compressive stress or reduced grain size.

[0047] Example 2: Preparation of TiO2 coating Step 1: Pre-treat the load substrate material by removing oil and dirt. The load-bearing substrate material used is a polytetrafluoroethylene (PTFE) plate with dimensions of 5*10cm and a thickness of 5mm. The pretreatment steps are as follows: wash with anionic surfactant detergent, then wash 3 times with clean water, wash 2 times with distilled water, rinse 2 times with 95% ethanol, and then dry in an oven at 60°C.

[0048] Step 2: Preparation of hydrosol TiO2 coating by silica sol modification Mix 5 parts TiO2, 5 parts silica sol, 0.1 parts defoamer (polydimethylsiloxane, DC-1430), 0.1 parts surfactant (octylphenol polyoxyethylene ether), 0.1 parts polyether-modified silicone oil (TEGO-450) diluted with propylene glycol (1:1 ratio), and 0.1 parts potassium chloride with 100 parts water. Gradually add the above materials, stirring at a speed of 300-800 rpm for at least 0.5 hours. After all materials have been added, continue stirring at the same speed for 1-2 hours to obtain modified hydrosol TiO2.

[0049] Silica sol: Produced by Shandong Kehanyuan New Materials Co., Ltd., KHZCM high-purity model. This silica sol is a dispersion medium (solvent) with no added organic solvents, belonging to an aqueous silica sol system; SiO2 solid content is 20%~30%, corresponding to a water content of 70%~80%; it is a 20-120 nanometer-scale silica solvent.

[0050] Defoamer: Polydimethylsiloxane (DC-1430) Surfactant: Produced by Guangzhou Hengyu Chemical Co., Ltd., Dow X-405, octylphenol polyoxyethylene ether.

[0051] The propylene glycol-diluted polyether-modified silicone oil (TEGO-450) was used at a 1:1 ratio, effectively ensuring its dispersion in this aqueous system. The polyether-modified silicone oil, through its long-chain molecules, creates steric hindrance, effectively preventing TiO2 particle aggregation. Potassium chloride, by regulating the system's ionization balance and optimizing the double-layer structure, works synergistically to ensure stable dispersion of TiO2 particles in the silica sol, thereby maximizing its photocatalytic effect in subsequent processes.

[0052] Step 3: Disperse The hydrosol prepared in step two is dispersed by ultrasonication for 15 minutes and then coated onto the substrate prepared in step one by flat coating to obtain a composite film.

[0053] The coating is prepared using 2000g of modified hydrosol TiO2 per square meter of substrate.

[0054] Step Four: The composite film prepared in step three is placed in a drying oven and heated gradually from room temperature to 40℃-80℃ over 20 minutes, and maintained for 6-12 hours for drying. This yields a highly adhesive TiO2 photocatalytic coating.

[0055] The prepared TiO2 photocatalytic coating appears white on the substrate and consists of TiO2 nanoparticles with a particle size of approximately 20-30 nm. Under room temperature and normal pressure conditions, the coating adhesion was tested using the cross-cut adhesion test according to GB / T9286-2021: the adhesion grade was 0.

[0056] Image analysis like Figure 1 As shown, XRD tests were performed on samples of the obtained TiO2 coating, and the results showed that the TiO2 nanoparticles in the coating were anatase phase with exposed (001) crystal planes.

[0057] like Figures 2-5 As shown, the transmission electron microscope image visually presents the microstructure of the TiO2 nanosheets exposed on the (001) crystal plane. Figure 2The image is a low-magnification TEM image with a scale bar of 200 nm, showing the microstructure of TiO2 nanosheets. Figure 3 The image is a medium magnified TEM image with a scale bar of 50 nm, showing the microstructure of TiO2 nanosheets. Figure 4 The microstructure of TiO2 nanosheets is shown in a high-magnification TEM image with a scale bar of 20 nm. Figure 5 The image is a high-resolution TEM image with a scale bar of 5 nm, showing the microstructure of TiO2 nanosheets.

[0058] like Figures 6-9 As shown, Figure 6 The distribution and aggregation state of TiO2 nanoparticles are clearly shown. Figure 7 , Figure 8 and Figure 9 The elemental distribution map clearly shows the distribution of elements in the TiO2 coating. Figure 7 The image shows a face-centered cubic crystal structure of Si, exhibiting a nanoscale silicon morphology with a size of approximately 50 nm. Figure 8 The diagram shows an O-plane triangular structure, which appears as a crystal with a size of approximately 50 nm. Figure 9 The image shows a Ti planar triangular structure, which appears as nanoparticles with a size of approximately 50 nm.

[0059] As shown in the figure above, the elemental distribution of Si, O, and Ti is in a particulate state. The calculated component ratio is 1:6:3, and the distribution pattern is a multi-component composite, which conforms to the design principles of composite material raw materials, the theory of colloid fraction stability, the theory of closest packing, and the theory of interface chemistry. Example 3:

[0060] In this embodiment, the titanium dioxide prepared by the method of Example 1 is different in that its grinding particle size is 30-50nm.

[0061] The preparation method is the same as in Example 2, except for step two: 10 parts by weight of TiO2 powder, 10 parts by weight of silica sol, 1 part by weight of defoamer polydimethylsiloxane (DC-1430), 0.1 parts by weight of surfactant (octylphenol polyoxyethylene ether), and 0.1 parts by weight of polyether-modified silicone oil (TEGO-450) diluted with propylene glycol at a ratio of 1:1, totaling 0.1 parts; 0.1 parts by weight of potassium chloride; and 100 parts by weight of water. The mixture was stirred at 800 r / min for 2 h.

[0062] The coating is prepared using 1000g of modified hydrosol TiO2 per square meter of substrate.

[0063] TiO2 photocatalytic coatings were prepared in this way.

[0064] Figure 10The image shows a bar graph illustrating the formaldehyde conversion rate-time curve of the highly adhesive nano-TiO2 photocatalytic coating with exposed (001) crystal faces prepared in this embodiment under fluorescent lamp irradiation conditions. Calculated in minutes, a formaldehyde removal efficiency of 95.7% is achieved at 60 minutes.

[0065] Experimental procedure: The TiO2 photocatalytic coating prepared above was applied to the substrate and dried. Then, it was placed in the reaction tank of a gas-solid reactor with a thickness of 5 mm and a circulating air. Under room temperature conditions, when the formaldehyde inlet concentration generated by the formaldehyde gas generator reached about 40 ppm, a formaldehyde removal experiment was carried out at a distance of 5-10 cm from the gas-solid reactor using a 300W fluorescent lamp.

[0066] Specific data can be found in the formaldehyde conversion rate-time data table, which shows that the formaldehyde conversion rate reaches 95.7% after 1 hour of exposure to fluorescent light.

[0067] Figure 11 The figure shows a bar chart of formaldehyde conversion rate versus time for the highly adhesive nano-TiO2 photocatalytic coating with exposed (001) crystal faces prepared in this embodiment under fluorescent lamp irradiation conditions. Calculated in hours, a formaldehyde removal efficiency of 97.43% is achieved after 12 hours.

[0068] The experimental procedure was the same as above. After 1 hour of exposure to sunlight, the formaldehyde conversion rate reached 95.70%, and after 12 hours of exposure, the formaldehyde conversion rate reached 97.43%.

[0069] The coating adhesion was tested using the cross-cut test according to GB / T9286-2021: a grid with a spacing of 1 mm was cut on the coating surface, the coating peeling was observed and rated. If the coating did not peel off, the result showed that the adhesion was grade 0, indicating that the coating was well bonded to the substrate. Example 4:

[0070] In this embodiment, the titanium dioxide prepared by the method of Example 1 is different in that its grinding particle size is 20-30nm.

[0071] The preparation method is the same as in Example 2, except for step two: 15 parts by weight of TiO2 powder, 10 parts by weight of silica sol, 0.5 parts by weight of defoamer polydimethylsiloxane (DC-1430), 0.1 parts by weight of surfactant (octylphenol polyoxyethylene ether), and 0.1 parts by weight of polyether-modified silicone oil (TEGO-450) diluted with propylene glycol at a ratio of 1:1, totaling 0.1 parts; 0.1 parts by weight of potassium chloride; and 100 parts by weight of water. The mixture was stirred at 800 r / min for 2 h.

[0072] The coating is prepared using 1500g of modified hydrosol TiO2 per square meter of substrate.

[0073] TiO2 photocatalytic coatings were prepared in this way.

[0074] Experimental procedure: The TiO2 photocatalytic coating prepared above was applied to the substrate and dried. Then, it was placed in the reaction tank of a gas-solid reactor with a thickness of 5 mm and circulating air. Under room temperature conditions, when the formaldehyde inlet concentration generated by the formaldehyde gas generator reached about 40 ppm, a formaldehyde removal experiment was conducted using a 6W ultraviolet lamp at a distance of 5-10 cm from the gas-solid reactor. After 1 hour of ultraviolet light irradiation, the formaldehyde conversion rate reached 97.86%, and after 12 hours of irradiation, the formaldehyde conversion rate reached 99.21%.

[0075] Figure 12 The image shows a bar graph illustrating the formaldehyde conversion rate-time curve of the highly adhesive nano-TiO2 photocatalytic coating with exposed (001) crystal faces prepared in Example 4 under weak ultraviolet light irradiation. Calculated in minutes, a formaldehyde removal efficiency of 97.86% is achieved at 60 minutes.

[0076] Figure 13 The figure shows a bar chart of formaldehyde conversion rate-time of the highly adhesive nano-TiO2 photocatalytic coating with (001) crystal facets prepared in Example 4 under weak ultraviolet light irradiation conditions. The formaldehyde removal effect reaches 99.21% after 12 hours, calculated in hours.

[0077] The coating adhesion was tested using the cross-cut test according to GB / T9286-2021: a grid with a spacing of 1 mm was cut on the coating surface, the coating peeling was observed and rated. If the coating did not peel off, the result showed that the adhesion was grade 0, indicating that the coating was well bonded to the substrate. Example 5:

[0078] In this embodiment, the titanium dioxide prepared by the method of Example 1 is different in that its grinding particle size is 30-50nm.

[0079] The preparation method is the same as in Example 2, except for step two: 20 parts by weight of TiO2 powder, 10 parts by weight of silica sol, 0.5 parts by weight of defoamer polydimethylsiloxane (DC-1430), 0.1 parts by weight of surfactant (octylphenol polyoxyethylene ether), and 0.2 parts by weight of polyether-modified silicone oil (TEGO-450) diluted with propylene glycol at a ratio of 1:1, with potassium chloride at 0.2 parts by weight; and 100 parts by weight of water. The mixture is stirred at 800 r / min for 2 h.

[0080] The coating is prepared using 2000g of modified hydrosol TiO2 per square meter of substrate.

[0081] Experimental procedure: The TiO2 photocatalytic coating prepared above was applied to the substrate and dried. Then, it was placed in the reaction tank of a gas-solid reactor with a thickness of 5 mm and circulating air. Under room temperature conditions, when the formaldehyde inlet concentration generated by the formaldehyde gas generator reached about 40 ppm, a formaldehyde removal experiment was carried out using a 6 W ultraviolet lamp at a distance of 5-10 cm from the gas-solid reactor. After 12 h of ultraviolet light irradiation, the formaldehyde conversion rate reached 100%.

[0082] Figure 14 The figure shows a bar chart of formaldehyde conversion rate-time of the highly adhesive nano-TiO2 photocatalytic coating with (001) crystal facets exposed prepared in Example 5 under ultraviolet light irradiation conditions. The formaldehyde removal effect is 100% when the time is 12 hours, calculated in hours.

[0083] The formaldehyde conversion rates under ultraviolet lamp irradiation conditions in Examples 3, 4, and 5 were compared, and the results are shown in Table 1 below. Table 1: Comparison of formaldehyde conversion rate and time in three examples The coating adhesion was tested using the cross-cut test according to GB / T9286-2021: a grid with a spacing of 1 mm was cut on the coating surface, the coating peeling was observed and rated. If the coating did not peel off, the result showed that the adhesion was grade 0, indicating that the coating was well bonded to the substrate. Example 6:

[0084] In this embodiment, the titanium dioxide prepared by the method of Example 1 is different in that its grinding particle size is 30-50nm.

[0085] The preparation method is the same as in Example 2, except for step two: 20 parts by weight of TiO2 powder, 20 parts by weight of silica sol, 0.5 parts by weight of defoamer polydimethylsiloxane (DC-1430), 0.2 parts by weight of surfactant (octylphenol polyoxyethylene ether), and 0.2 parts by weight of polyether-modified silicone oil (TEGO-450) diluted with propylene glycol at a ratio of 1:1, totaling 0.2 parts; 0.2 parts by weight of potassium chloride; and 100 parts by weight of water. The mixture was stirred at 800 r / min for 2 h.

[0086] Step three does not use a coating method. Instead, under room temperature and normal pressure, an electric spray gun is used to evenly spray the coating onto a 25*35cm HEPA filter, ensuring a screen thickness of 0.02mm. This process is repeated to prepare four HEPA filters with a photocatalytic titanium dioxide coating, which are then air-dried.

[0087] Under ambient temperature and pressure conditions, a multifunctional portable gas analyzer was used to measure the 24-hour ammonia concentration in a bathroom with an initial ammonia concentration of 7.5 ppm. Under the same conditions, a simple air purifier device was constructed using four HEPA filters and a UV lamp. This device was placed in the bathroom with an initial ammonia concentration of 7.5 ppm. After turning on the UV lamp, the multifunctional portable gas analyzer was used to measure the 24-hour ammonia concentration in the bathroom. The two sets of data were compared. Figure 15 As shown.

[0088] According to the comparison chart before and after ammonia purification, under weak ultraviolet light excitation, the titanium dioxide coating effectively accelerated the degradation of ammonia through photocatalysis, significantly reducing the equilibrium concentration of ammonia.

[0089] Figure 15 This table compares the ammonia concentration-time curves of the highly adhesive nano-TiO2 photocatalytic coating with exposed (001) crystal planes prepared in Example 6 under weak ultraviolet light irradiation. Under weak ultraviolet light excitation, the highly adhesive nano-TiO2 photocatalytic coating effectively accelerated the degradation of ammonia through photocatalysis, significantly reducing the equilibrium concentration of ammonia.

[0090] The coating adhesion was tested using the cross-cut test according to GB / T9286-2021: a grid with a spacing of 1 mm was cut on the coating surface, the coating peeling was observed and rated. If the coating did not peel off, the result showed that the adhesion was grade 0, indicating that the coating was well bonded to the substrate. Example 7:

[0091] In this embodiment, the titanium dioxide prepared by the method of Example 1 is different in that its grinding particle size is 30-50nm.

[0092] The preparation method is the same as in Example 2, except for step two: 20 parts by weight of TiO2 powder, 20 parts by weight of silica sol, 0.5 parts by weight of defoamer polydimethylsiloxane (DC-1430), 0.2 parts by weight of surfactant (octylphenol polyoxyethylene ether), and 0.2 parts by weight of polyether-modified silicone oil (TEGO-450) diluted with propylene glycol at a ratio of 1:1, totaling 0.2 parts; 0.2 parts by weight of potassium chloride; and 100 parts by weight of water. The mixture was stirred at 800 r / min for 2 h.

[0093] Step 3 does not use a coating method, but sprays it onto the petri dish at room temperature and normal pressure. The petri dish is then placed in a drying oven at 40℃ and dried for 6 hours to obtain a coating with a thickness of 125μm. A cross-cutting tool is used to cut a grid with a spacing of 1mm on the surface of the coating. There is no peeling of the coating within the grid, and the coating adhesion level is 0.

[0094] Figure 16The adhesion grade test diagram of the titanium dioxide photocatalytic coating with (001) crystal facets exposed prepared in Example 7 under room temperature and normal pressure conditions.

[0095] Cut a grid with a 1mm spacing on the coating surface using a cross-cutting tool, observe the coating peeling and rate it. If there is no peeling, the adhesion is rated as 0.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly adhesive nano-TiO2 photocatalytic coating, characterized in that... The components include the following parts by weight: 100 parts water; 5-20 parts TiO2 nanoparticles; 5-20 parts silica sol; 0.5-1 part polydimethylsiloxane; Octylphenol polyoxyethylene ether, 0.1-0.2 parts; 0.1-0.2 parts of polyether-modified silicone oil diluent, prepared by mixing polyether-modified silicone oil and propylene glycol in a 1:1 weight ratio; 0.1-0.2 parts of potassium chloride; wherein, The TiO2 nanoparticles are nanoparticles with exposed 001 crystal planes, and are prepared using the following method: Step 1. Take a 100mL beaker and add 50mL of tetrabutyl titanate; Step 2. Control the magnetic stirrer speed to 500-600 r / min, slowly add 6 mL of hydrofluoric acid to the beaker, and continue stirring for 2 hours; Step 3. Transfer the solid-liquid mixture obtained in Step 2 to a reaction vessel and react at 180°C for 24 hours. After the reaction is completed, perform vacuum filtration. Step 4. Dry the solid material obtained in Step 3 and grind it to a particle size of less than 50 nm to obtain nano-TiO2 nanoparticle powder.

2. The preparation method of the high-adhesion nano-TiO2 photocatalytic coating as described in claim 1, characterized in that: Mix 5-20 parts TiO2 nanoparticles, 5-20 parts silica sol, 0.5-1 parts defoamer polydimethylsiloxane, 0.1-0.2 parts octylphenol polyoxyethylene ether; dilute polyether-modified silicone oil (TEGO-450) with propylene glycol at a ratio of 1:1, totaling 0.1-0.2 parts; add 0.1-0.2 parts potassium chloride; and 100 parts water thoroughly. Gradually add the above materials, stirring at a speed of 300-800 r / min for at least 0.5 h; after adding all materials, continue stirring at the same speed for 1-2 h to obtain modified hydrosol TiO2. The modified hydrosol TiO2 is dispersed by ultrasonication and then coated onto the corresponding substrate by flat coating or spraying to obtain a composite film; after heating and drying, a highly adhesive TiO2 photocatalytic coating is obtained.

3. The application method of the high-adhesion nano-TiO2 photocatalytic coating as described in claim 2, characterized in that: The modified hydrosol TiO2 was ultrasonically dispersed for 15 minutes and then coated onto a polytetrafluoroethylene substrate in a flat coating manner to obtain a composite film; 1000-2000g of modified hydrosol TiO2 was used per square meter of substrate to prepare the coating. The composite film is placed in a drying oven and heated gradually from room temperature to 40℃-80℃ over 20 minutes, and maintained for 6-12 hours for drying treatment; finally, a highly adhesive TiO2 photocatalytic coating is obtained.

4. The high-adhesion nano-TiO2 photocatalytic coating as described in claim 2, characterized in that: After dispersing the modified hydrosol TiO2 with ultrasound for 15 minutes, the coating is evenly sprayed onto the HEPA filter screen using an electric spray gun, ensuring that the screen thickness is above 0.02 mm. After drying, a highly adhesive TiO2 photocatalytic coating is obtained.

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