A gas-permeable wall material based on VOCs concentration control of gas flow and a preparation method and application thereof

Abstract

The present application relates to the field of building technology, in particular to a kind of gas permeability wall material based on VOCs concentration control gas flow and its preparation method and application.Gas permeability wall material is prepared from the following components by weight fraction: activated carbon fiber 65-55 parts, silicon dioxide particles 5-15 parts, titanium dioxide nanoparticles 5-20 parts, silica sol (SiO2·H2O) 15-20 parts, nitrogen-doped visible light responsive titanium dioxide 20-30 μm coating, silica aerogel 20-30 μm coating and silica sol 2-3 mm coating.The present application realizes natural penetration by designing the gradient structure of porous composite material, utilizes the concentration difference of indoor and outdoor VOCs to drive directional diffusion of pollutants, and simultaneously has light permeability and structural stability.This material can be widely used in residential, commercial, educational, medical, hotel and other building types, can significantly improve indoor air quality, and especially creates a healthy, low-noise indoor environment for sleep.

Description

Technical Field

[0001] This invention relates to the field of building technology, and in particular to a breathable wall material based on VOC concentration-controlled gas flow, a method for preparing its blocks, and its application in masonry construction. Background Technology

[0002] Humans spend over 90% of their time in buildings, making the air quality of our living environment a direct impact on human health. Studies show that exposure to certain concentrations of VOCs can cause short-term symptoms such as headaches, dizziness, and eye and throat discomfort. Long-term exposure can lead to respiratory diseases, weakened immune function, and even cancer. Children, pregnant women, and the elderly are particularly sensitive to VOCs. As a major source of harmful gaseous pollutants in human living environments, VOCs are widely recognized for their origins in interior decoration materials (plywood, paint, flooring, and wallpaper), furniture (adhesives, varnishes), and daily chemical reagents (cleaners, air fresheners). However, it's important to note that human metabolism is also a significant source of VOCs. The main VOCs contributing to human metabolism are isoprene from respiration and acetone from skin volatilization.

[0003] Modern residential buildings use mechanical ventilation systems, such as air conditioners and fans, which primarily manage the temperature and humidity of the recirculated air, offering limited ability to regulate air cleanliness. Natural ventilation, on the other hand, requires a minimum of 30m³ of fresh air. 3 Human comfort standards emphasize high airtightness in building energy conservation requirements (passive houses require windows and doors to be less than 0.6m high airtightness). 3 / h·m 2 Therefore, the primary way to supplement fresh air is still by opening windows. However, regarding the nighttime sleeping environment, ancient texts record that slightly opening doors and windows can allow "thief winds" to enter the body, opening the body's defenses and allowing cold, dampness, dryness, and heat to invade (according to the *Huangdi Neijing*, "avoid the treacherous winds when they are weak," meaning that the ancients kept doors and windows tightly closed while sleeping to seal and conserve their energy). This is especially true for pregnant women, the elderly, and children, who are physically weak, as opening windows at night can lead to various health problems.

[0004] In the bedroom, under conditions of high airtightness, mechanical ventilation, and no windows, VOCs produced by human metabolism accumulate continuously during nighttime sleep. Modern residential architecture prioritizes practical design with large living rooms and small bedrooms, with bedroom areas ranging from only 9-15 square meters. 2 With a ceiling height of 2.8m, and assuming 1-4 people spend approximately 1 / 3 to 1 / 2 of their time (8-12 hours) sleeping together in the same bedroom, the cumulative increase in TVOC concentration due to human metabolism at night can reach as high as 400μg / m³. 3 (Initial TVOC was 120 μg / m³) 3 After 8 hours, the TVOC was 620 μg / m³. 3This exceeds the WHO's recommended long-term exposure limit for VOCs (200–300 μg / m³). 3 Approximately 2 to 3 times.

[0005] The air quality of the sleep environment directly affects sleep quality. Some components of VOCs have been reported to be irritating, potentially triggering respiratory inflammation, coughing, or difficulty breathing. These symptoms may worsen at night, leading to sleep interruptions or difficulty falling asleep, thus reducing sleep quality. Some VOCs are neurotoxic, potentially affecting the central nervous system and causing symptoms such as headaches, dizziness, fatigue, and difficulty concentrating. These symptoms may also worsen at night, interfering with falling asleep or causing awakenings, thereby affecting the continuity and depth of sleep. VOCs may induce or exacerbate allergic reactions, such as nasal congestion, runny nose, or itchy skin. These symptoms may be more pronounced at night, leading to restless sleep or frequent awakenings. Long-term exposure to certain concentrations of VOCs may trigger anxiety or depression. These psychological problems are closely related to sleep disorders and may lead to insomnia or decreased sleep quality.

[0006] Current methods for treating VOCs in indoor environments include active methods such as adsorption, photocatalysis, ozone oxidation, low-temperature plasma, and biodegradation, which have drawbacks such as high energy consumption and byproducts. Passive methods mainly consist of plant adsorption (which has uncontrollable efficiency issues) and ventilation. Ensuring airtightness while achieving breathability in the building envelope has become a development direction for passive ventilation. Existing breathable wall technologies mainly include the following two types:

[0007] By utilizing pre-embedded ventilation components or special structural designs, the ventilation technology of the wall is realized, allowing air to flow through the wall and enabling the wall to serve both enclosure and ventilation functions. For example, patent CN202210123456.5 uses temperature and humidity sensors and micro fans to dynamically adjust the airflow path inside the wall; patent CN201920987654.3 designs a honeycomb ventilation structure, which enhances the efficiency of natural convection heat transfer by optimizing the layout of the pores.

[0008] The use of phase change materials (PCM), aerogels, and porous materials (such as diatomaceous earth and wood) to construct porous structures or airflow channels in breathable walls can achieve automatic regulation of internal and external heat and moisture exchange. For example, patent CN201910012345.X uses paraffin / expanded graphite composite phase change materials embedded in a porous cement matrix to achieve autonomous heat absorption and release regulation of the wall; patent CN202010567890.1 combines solar collectors and PCM walls to dynamically regulate building thermal inertia; patent CN201811234567.8 utilizes the moisture absorption and release properties of diatomaceous earth and zeolite to achieve natural dehumidification of the wall; and patent CN202110789012.3 designs a porous structure of straw fiber or bamboo charcoal, giving the wall the functions of heat preservation, humidity regulation, and CO2 adsorption.

[0009] The aforementioned breathable wall technologies all aim to regulate the indoor thermal and humidity environment and reduce mechanical energy consumption. The architectural technology team at the University of Science and Technology of China studied the optimal porosity, air infiltration path, thermal and humidity coupling, and energy storage of the breathable wall. Only when verifying the reliability of the breathable wall system did they test the concentration of PM2.5 and CO2 in the indoor air due to natural air infiltration in a physical laboratory.

[0010] No technology has been found to control indoor air quality using breathable wall systems, especially no reports on their ability to regulate VOCs. Summary of the Invention

[0011] To address the aforementioned issues, this invention provides a method for preparing a breathable wall material based on VOC concentration-controlled gas flow, and designs its block preparation and masonry application to achieve prefabricated masonry construction of non-load-bearing walls such as those under windows. This invention is a passive wall system with dynamically adjustable VOC concentration, using the concentration difference of volatile organic compounds (VOCs) between indoors and outdoors as the driving force to unidirectionally guide indoor VOCs to diffuse outdoors. Through steady-state infiltration, it reduces the high concentration of VOCs accumulated in bedrooms at night, consuming no energy and producing no noise, thus improving sleep quality and promoting health. Simultaneously, the material possesses a certain degree of light transmittance, also increasing indoor lighting.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] This invention provides a breathable wall material based on VOC concentration-controlled gas flow, prepared from the following components in parts by weight:

[0014] 65-55 parts activated carbon fiber, 5-15 parts silica particles, 5-20 parts titanium dioxide nanoparticles, and 15-20 parts silica sol (SiO2·H2O).

[0015] The activated carbon fiber has a micropore size of <2nm, or a mesopore size of 2-50nm, or a macropore size of >50nm.

[0016] The present invention also provides a method for preparing the breathable wall material described in the above technical solution, comprising the following steps:

[0017] 1) Activated carbon fibers with micropore size <2nm, mesopore size 2-50nm or macropore size >50nm are thoroughly stirred with silica particles, titanium dioxide nanoparticles and silica sol to form three mixtures; the diameter of the silica particles is 20nm and the diameter of the titanium dioxide nanoparticles is 1-10nm.

[0018] 2) The three mixtures are filled into a mold and subjected to three hot-pressing curing processes to obtain blocks.

[0019] Preferably, the conditions for thorough stirring in step 1) include:

[0020] Three types of activated carbon fibers with different particle sizes were respectively added to silica particles and titanium dioxide nanoparticles and thoroughly dry-mixed in a silica sol with a mass fraction of 25%–35% to obtain dry mix 1, dry mix 2, and dry mix 3. These were then dry-mixed in a high-speed mixer for 5–10 minutes at a speed of 500–800 r / min to form three colloidal mixtures. The silica sol had a particle size of 8–20 nm, a pH of 6–7, and a density of 1.1–1.25 g / cm³. 3 ;

[0021] The mass ratio of activated carbon fiber with a micropore size of <2nm to silica particles, titanium dioxide nanoparticles, and silica sol in the dry mixture 1 is 65:15:5:15.

[0022] The dry mixture 2 has a mesopore size of 2-50 nm and a mass ratio of silica particles, titanium dioxide nanoparticles, and silica sol of 60:10:10:20.

[0023] The mass ratio of activated carbon fiber with a macropore size >50nm to silica particles, titanium dioxide nanoparticles, and silica sol in the dry mixture 3 is 55:5:20:20.

[0024] Preferably, the gel-like dry mixture 1 obtained in step 1) of the above technical solution is filled into the mold with a thickness of 80mm. After hot pressing, dry mixture 2 is filled into the mold with a thickness of 70mm. After hot pressing, dry mixture 3 is filled into the mold with a thickness of 50mm and then hot pressed. The gel-like mixture is sequentially filled into the mold with a special structural design in layers and cured by three hot pressings. The design size of the mold is the size of the block.

[0025] The mold measures 300mm × 200mm × 90mm and has a socket structure. The upper and lower frame surfaces of the mold have four mortise and tenon joints, and the left and right frame surfaces have a total of six mortise and tenon joints. The socket is a cylindrical structure with a diameter of 10mm and a height of 10mm, and the insertion is a cylindrical structure with a diameter of 10mm and a depth of 10mm.

[0026] The hot pressing process is as follows:

[0027] Fill 2100-2200g of dry mix 1 into the mold, with a filling thickness of 80mm, and hot press it at a temperature of 70℃-80℃, a pressure of 15-20Mpa, and a time of 60-90 seconds to obtain the indoor layer;

[0028] Fill 1400-1500g of dry mix 2 into the mold, spread it evenly on the top of the inner layer, with a filling thickness of 70mm, and hot press it at a temperature of 70℃-80℃, a pressure of 8-10Mpa, and a time of 60-90 seconds to obtain the middle layer;

[0029] Fill 700-800g of dry mix 3 into the mold, spread it evenly on top of the middle layer, with a filling thickness of 50mm, and maintain the temperature and pressure at 70℃-80℃ and 3-5Mpa for 0.5h to obtain the outdoor layer;

[0030] After natural cooling and demolding, the demolded blocks are placed in an oven preheated to 80℃ and heated to 120℃ at a rate of 1-3℃ / min, and held at that temperature for 2-4 hours to obtain a three-layer structure blank block with densities of 0.8-1 g / cm³ for the inner, middle, and outer layers. 3 0.6~0.8g / cm 3 0.4~0.6g / cm 3 The pore sizes are approximately 5–10 nm, 5–30 nm, and 30–100 nm, respectively, and the porosities are 55–60%, 65–70%, and 75–80%, respectively.

[0031] Preferably, the obtained blank blocks are coated on two functional surfaces and four frame surfaces.

[0032] The functional surface coating consists of nitrogen-doped visible light responsive titanium dioxide on the outer side (outdoor layer) with a thickness of 20–30 μm and a mass concentration of 3 mg / ml; and silica aerogel on the inner side (indoor layer) with a thickness of 20–30 μm and a mass concentration of 0.85 g / ml.

[0033] The frame surface is the top, bottom, left, and right sides of the block. The coating is silica sol with a thickness of 2-3 mm and a mass concentration of 1.25 g / ml, resulting in a breathable wall block with a compressive strength of 3.5-8 MPa, a thermal conductivity of 0.25-0.5 W / (m·K), and a light transmittance of 30-50%.

[0034] Preferably, the breathable wall block has four mortise and tenon joints on the upper and lower frame surfaces and six mortise and tenon joints on the left and right frame surfaces. The socket is a cylindrical structure with a diameter of 10mm and a height of 10mm, and the insertion is a cylindrical structure with a diameter of 10mm and a depth of 10mm. The insertion and socket on each block surface are matched and fixed by insertion.

[0035] Preferably, the breathable wall blocks are hot-melted at 70℃~80℃ for 10~20s, then the frame surface is fixed and the blocks are stacked to form a wall.

[0036] This invention also provides the application of the breathable wall material described in the above technical solution in the treatment of VOCs in indoor environments.

[0037] The beneficial effects of this invention are:

[0038] 1. Completely passive: requires no energy consumption, relies on natural driving force due to concentration difference;

[0039] 2. Health and safety: No risk of secondary pollution such as ozone or plasma;

[0040] 3. Flexible assembly: The socket structure supports quick assembly and disassembly, making it suitable for modification projects.

[0041] This invention utilizes the gradient permeability of porous composite materials to drive the directional diffusion of pollutants by leveraging the concentration difference of VOCs between indoors and outdoors, while also possessing light transmittance and structural stability. This material can be widely applied to various building types, including residential, commercial, educational, medical, and hotel buildings, significantly improving indoor air quality, especially creating a healthy, low-noise indoor environment for sleep.

[0042] Applicable scenarios:

[0043] The exterior wall of the bedroom, below the window: replaces the traditional brick wall, continuously releasing VOCs (such as isoprene) metabolized by the human body at night.

[0044] The wall beneath the windows on the exterior of the office: reduces the concentration of benzene compounds released from printer ink and glue.

[0045] 1. Pore size gradient design: Inner layer (indoor side): smaller pore size (5-10nm), preferentially adsorbs VOCs; Middle layer: medium pore size (5-30nm), which is the transition section for VOCs adsorption and diffusion; Outer layer (outdoor side): larger pore size (30-100nm), which accelerates diffusion and release.

[0046] 2. Light transmittance: The silica particles are colorless and transparent particles, and the silica sol is colorless and transparent sol. When silica particles and silica sol are combined with activated carbon fiber, the light transmittance of the blocks can be enhanced, reaching 30% to 50% (a hazy lighting effect). Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0048] Figure 1 This is a schematic diagram of the building blocks;

[0049] Figure 2 This is a schematic diagram of the mold;

[0050] Figure 3 This is a diagram of part of the wall block. Detailed Implementation

[0051] This invention provides a breathable wall material for controlling gas flow based on VOC concentration, prepared from the following components in parts by weight: 65-55 parts activated carbon fiber, 5-15 parts silica particles, 5-20 parts titanium dioxide nanoparticles, and 15-20 parts silica sol (SiO2·H2O). The activated carbon fiber has a micropore size of <2 nm, or a mesopore size of 2-50 nm, or a macropore size of >50 nm. In this invention, the activated carbon fiber selectively adsorbs VOCs (isoprene, acetone, formaldehyde, etc.), enhancing the diffusion driving force. This invention does not specifically limit the source of the activated carbon fiber; those skilled in the art can use commercially available materials, such as high specific surface area activated carbon fiber (BET1800-2000) from Jiangsu Kejing Carbon Fiber Co., Ltd., located in Rudong, Jiangsu Province. In this invention, the silica particles have a porous structure, high hardness, and high light transmittance. Using silica particles not only enhances light transmittance but also strengthens the interparticle adhesion and build-up strength. This invention does not specifically limit the source of the silica particles; those skilled in the art can use commercially available materials, such as silica particles purchased from Shanghai Yingcheng New Materials Co., Ltd. in Shanghai. In this invention, the silica aerogel has an ultra-lightweight porous structure (porosity > 90%), reducing mass transfer resistance and enhancing light transmittance. This invention does not specifically limit the source of the silica aerogel; those skilled in the art can use commercially available materials, such as high-porosity aerogel purchased from Jiangxi Chenguang New Materials Co., Ltd. in Jiangxi. In this invention, the titanium dioxide nanoparticles function as photocatalytic degraders of VOCs under ultraviolet or visible light irradiation. Those skilled in the art can use commercially available materials, such as nano-titanium dioxide purchased from Shanghai Huijing Nanomaterials Co., Ltd. in Shanghai. In this invention, the nitrogen-doped visible-light-responsive titanium dioxide decomposes permeated VOCs under natural light (assisted degradation). In this invention, the nitrogen-doped visible light responsive titanium dioxide can be commercially available by those skilled in the art, such as that purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0052] The present invention also provides a method for preparing the breathable wall material described in the above technical solution, comprising the following steps:

[0053] 1) Activated carbon fibers with micropore size <2nm, mesopore size 2-50nm or macropore size >50nm are thoroughly stirred with silica particles, titanium dioxide nanoparticles and silica sol to form three mixtures; the diameter of the silica particles is 20nm and the diameter of the titanium dioxide nanoparticles is 1-10nm.

[0054] 2) The three mixtures are filled into a mold and subjected to three hot-pressing curing processes to obtain blocks.

[0055] In this invention, the preferred conditions for thorough stirring in step 1) include: adding activated carbon fibers of three particle sizes, silica particles, and titanium dioxide nanoparticles to a silica sol with a mass fraction of 25%–35% for thorough dry mixing to obtain dry mix 1, dry mix 2, and dry mix 3. These are then dry-mixed in a high-speed mixer for 5–10 minutes at a speed of 500–800 r / min to form three colloidal mixtures. The silica sol has a particle size of 8–20 nm, a pH of 6–7, and a density of 1.1–1.25 g / cm³. 3 The mass ratio of activated carbon fiber with a micropore size of <2nm to silica particles, titanium dioxide nanoparticles, and silica sol in dry mix 1 is 65:15:5:15; the mass ratio of activated carbon fiber with a mesopore size of 2-50nm to silica particles, titanium dioxide nanoparticles, and silica sol in dry mix 2 is 60:10:10:20; and the mass ratio of activated carbon fiber with a macropore size of >50nm to silica particles, titanium dioxide nanoparticles, and silica sol in dry mix 3 is 55:5:20:20.

[0056] In this invention, the gel-like dry mixture 1 obtained in step 1) of the above technical solution is filled into a mold with a thickness of 80mm. After hot pressing, dry mixture 2 is filled into the mold with a thickness of 70mm. After hot pressing, dry mixture 3 is filled into the mold with a thickness of 50mm and then hot pressed. The gel-like mixture is sequentially filled into a mold with a special structural design in layers and cured by three hot pressings. The design size of this mold is the size of the block. The mold size is 300mm×200mm×90mm, and the shape has a socket structure. The upper and lower frame surfaces of the mold have 4 mortise and tenon joints, and the left and right frame surfaces have a total of 6 mortise and tenon joints. The socket specifications are: a cylindrical structure with a diameter of 10mm and a height of 10mm, and the insertion specifications are: a cylindrical structure with a diameter of 10mm and a depth of 10mm. The preferred hot pressing process is: 2100-2200g of dry mixture 1 is filled into the mold with a filling thickness of... The inner layer is formed by hot pressing at 70℃~80℃, 15~20Mpa, and 60~90 seconds. 1400~1500g of dry mix 2 is filled into the mold and spread evenly above the inner layer to a thickness of 70mm. This is then hot-pressed at 70℃~80℃, 8~10Mpa, and 60~90 seconds to form the middle layer. 700~800g of dry mix 3 is then filled into the mold and spread evenly. Above the intermediate layer, a 50mm thick layer is filled and heated at 70℃~80℃ and 3~5MPa for 0.5 hours to obtain the outdoor layer. After natural cooling and demolding, the demolded blocks are placed in an oven preheated to 80℃ and heated to 120℃ at a rate of 1~3℃ / min, and held for 2~4 hours to obtain a three-layer structural blank block. The densities of the indoor, intermediate, and outdoor layers are 0.8~1g / cm³, respectively. 3 0.6~0.8g / cm 3 0.4~0.6g / cm 3 The pore sizes are approximately 5–10 nm, 5–30 nm, and 30–100 nm, respectively, and the porosities are 55–60%, 65–70%, and 75–80%, respectively.

[0057] In this invention, the obtained rough masonry blocks undergo coating treatment on two functional surfaces and four frame surfaces. The functional surface coating consists of nitrogen-doped visible-light-responsive titanium dioxide on the outer side (outdoor layer), with a thickness of 20–30 μm and a mass concentration of 3 mg / ml; and silica aerogel on the inner side (indoor layer), with a thickness of 20–30 μm and a mass concentration of 0.85 g / ml. The frame surfaces, which are the top, bottom, left, and right sides of the block, are coated with silica sol, with a thickness of 2–3 mm and a mass concentration of 1.25 g / ml, resulting in breathable wall blocks with a compressive strength of 3.5–8 MPa, a thermal conductivity of 0.25–0.5 W / (m·K), and a light transmittance of 30–50%.

[0058] In this invention, the breathable wall block has four mortise and tenon joints on the upper and lower frame surfaces, and a total of six mortise and tenon joints on the left and right frame surfaces. The socket is a cylindrical structure with a diameter of 10mm and a height of 10mm, and the insertion is a cylindrical structure with a diameter of 10mm and a depth of 10mm. The insertion and socket on each block surface are matched for insertion and fixing. In this invention, the breathable wall block is heat-fused at 70℃~80℃ for 10~20s to fix the frame surfaces and build up the wall.

[0059] This invention also provides the application of the breathable wall material described in the above technical solution in the treatment of VOCs in indoor environments.

[0060] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0061] Example 1

[0062] A method for preparing a breathable wall material based on VOC concentration-controlled gas flow includes the following steps:

[0063] (1) Substrate:

[0064] 1) Dry Mixture 1 Base Material Ratio:

[0065] The composition consists of 65% microporous activated carbon fiber (micropore size <2nm), 15% silica particles (diameter 20nm), 5% titanium dioxide nanoparticles (diameter 5nm), and 25% silica sol (mass fraction). The sol particle size is 20nm, pH = 6-7, and density is 1.2g / cm³. 3 )15%, all of which are percentages by weight.

[0066] 2) Dry Mixture 2 Base Material Ratio

[0067] The composition consists of 60% mesopore activated carbon fiber (30 nm), 10% silica particles (20 nm), 10% titanium dioxide nanoparticles (5 nm), and 30% silica sol (15 nm particle size, pH 6–7, density 1.1 g / cm³). 3 )20%, all of which are percentages by weight.

[0068] 3) Dry Mixture Base Material Ratio

[0069] The composition consists of 55% macroporous activated carbon fiber (pore size > 50 nm), 5% silica particles (diameter 20 nm), 20% titanium dioxide nanoparticles (diameter 5 nm), and 30% silica sol (mass fraction). The sol particle size is 15 nm, pH = 6–7, and density is 1.1 g / cm³. 3 )20%, all of which are percentages by weight.

[0070] (2) Substrate preparation:

[0071] Dry mix 1 (microporous activated carbon fiber formulation) 65:15:5:15, dry mix 2 (medium-pore activated carbon fiber formulation) 60:10:10:20, and dry mix 3 (large-pore activated carbon fiber formulation) 55:5:20:20 were each dry-mixed for 10 minutes in a high-speed mixer (speed 500–800 r / min) to form three colloidal mixtures.

[0072] Hot pressing: 2100g of dry mix 1 is filled into the mold to a thickness of 80mm, and hot-pressed at 70℃~80℃, 15Mpa, and 90 seconds to obtain the inner layer; 1500g of dry mix 2 is filled into the mold, spread evenly on top of the inner layer to a thickness of 70mm, and hot-pressed at 70℃~80℃, 10Mpa, and 90 seconds to obtain the middle layer; 800g of dry mix 3 is filled into the mold. The inner layer is laid flat on top of the middle layer, with a filling thickness of 50mm. It is then heated to 70℃~80℃ and pressure 5MPa, maintained at this temperature and pressure for 0.5 hours to obtain the outer layer. After natural cooling, the blocks are demolded. The demolded blocks are placed in an oven preheated to 80℃, and the temperature is increased (at a rate of 1~3℃ / min) to 120℃ and held for 4 hours to obtain a three-layer structure blank block. The densities of the inner, middle, and outer layers are approximately 1g / cm³. 3 0.8g / cm 3 0.6g / cm 3 The pore sizes are approximately 5–10 nm, 5–30 nm, and 30–100 nm, respectively, with porosities of 60%, 70%, and 80%. The blocks have a compressive strength of 5 MPa, a thermal conductivity of 0.3 W / (m·K), and a light transmittance of 50%.

[0073] (3) Modular blocks:

[0074] Each block measures 300mm × 200mm × 90mm. The top and bottom frame surfaces each have four socket joints, and the left and right frame surfaces each have a total of six socket joints. The sockets are cylindrical structures with a diameter and height of 10mm, and the inserts are cylindrical structures with a diameter and depth of 10mm. The inserts and sockets on the block surface are fixed together.

[0075] (4) Surface treatment:

[0076] Photocatalytic coating: A nitrogen-doped visible light responsive titanium dioxide solution with a thickness of 30 μm and a mass concentration of 3 mg / ml is sprayed onto the outdoor side surface to degrade the emitted VOCs using natural light.

[0077] Hydrophobic layer: The interior side is sprayed with silica aerogel solution with a thickness of 30μm and a mass concentration of 0.85g / ml to prevent water vapor from clogging the micropores.

[0078] Frame surface coating: Apply silica sol to the top, bottom, left and right sides with a thickness of 3mm and a mass concentration of 1.25g / ml, insert and heat-melt, and build up the wall.

[0079] (5) Efficiency decay and stability characteristics

[0080] The initial wall constructed from masonry blocks reduces indoor VOCs by up to 80%, and after a year of adsorption, the reduction in indoor VOCs will stabilize at 60%.

[0081] Table 1 Performance Indicators of Block Walls

[0082]

[0083] Cabin simulation test: 1m 3 One side of the hexahedral cabin is the block wall of this invention, and nitrogen is introduced into the front cabin at 620 μg / m³. 3 Isoprene was continuously pressurized with nitrogen at 1 atm. After 12 hours, the concentration in the rear chamber was measured to be 130 μg / m³. 3 The above purification effect was obtained.

[0084] Example 2

[0085] (1) Substrate:

[0086] 1) Dry Mixture 1 Base Material Ratio:

[0087] Diatomaceous earth (pore size 1μm) 30%, microporous activated carbon fiber (micropore size <2nm) 45%, TiO2 nanoparticles (particle size 50nm) 5%, PLA resin (particle size 0.5mm) 20%, all of the above are mass percentages.

[0088] 2) Dry Mixture 2 Base Material Ratio

[0089] Diatomaceous earth (pore size 1μm) 20%, macroporous activated carbon fiber (pore size >50nm) 45%, TiO2 nanoparticles (particle size 50nm) 15%, PLA resin (particle size 0.5mm) 20%, all of the above are mass percentages.

[0090] (2) Substrate preparation:

[0091] Dry mix 1 (microporous activated carbon fiber formulation, by mass ratio) 30:45:5:20 and dry mix 2 (macroporous activated carbon fiber formulation, by mass ratio) 20:45:15:20 were respectively dry-mixed in a high-speed mixer for 10 minutes (speed 500–800 r / min) to form two premixes, premix 1 and premix 2.

[0092] Two premixed materials were separately fed into a twin-screw extruder for melt co-extrusion (L / D = 40). The melt co-extrusion operating parameters were: temperature 180℃, screw speed 70 r / min, extrusion section pressure controlled at 10 MPa, discharge water tank temperature 15℃, and cooling time 10 s. The extruded particles (particle size 1-2 mm) were placed in an oven for drying at 110℃ for 5 hours. Two composite materials, composite material 1 and composite material 2, were obtained.

[0093] 3D printing molding: Using composite material 1 as the printing material, FDM 3D printing equipment is used to print blocks. The nozzle diameter is 0.1mm, the layer height is 0.1mm, the printing speed is 30mm / s, the printing temperature is 200℃, and the printed block size is 300mm×80mm×90mm. Two sockets are printed on the left and right frame surfaces of the block. The socket specifications are: cylindrical structures with a diameter of 10mm and a height of 10mm. The insertion specifications are: cylindrical structures with a diameter of 10mm and a depth of 10mm, thus obtaining the interior layer block. Using composite material 2 as the printing material, FDM 3D printing equipment was used to print blocks. The nozzle diameter was 0.1mm, the layer height was 0.1mm, the printing speed was 30mm / s, the printing temperature was 200℃, and the printed block size was 300mm×120mm×90mm. Four sockets were printed on the upper and lower frame surfaces of the block, and four sockets were printed on the left and right frame surfaces. The socket specifications were: cylindrical structures with a diameter of 10mm and a height of 10mm, and the insertion specifications were: cylindrical structures with a diameter of 10mm and a depth of 10mm. Fifty biomimetic capillary channels with a diameter of 200μm were evenly hollowed out and printed in the middle of the block to obtain the outdoor layer block.

[0094] Thermally fused blocks: Indoor and outdoor blocks are overlapped and hot-pressed to fuse them into a single block measuring 300mm × 200mm × 90mm. The hot-pressing temperature is 190℃ and the pressure is 5MPa, resulting in a two-layer structural blank block. The densities of the indoor and outdoor layers are approximately 0.9g / cm³. 3 0.7g / cm 3 The pore sizes are approximately 0.1–1 μm and 10–50 μm, respectively, with porosities of 50% and 60%, respectively. The blocks have a compressive strength of 4 MPa, a thermal conductivity of 0.35 W / (m·K), and a light transmittance of 60%.

[0095] (3) Modular blocks:

[0096] Each block measures 300mm × 200mm × 90mm. The top and bottom frame surfaces each have four socket joints, and the left and right frame surfaces each have a total of six socket joints. The sockets are cylindrical structures with a diameter and height of 10mm, and the inserts are cylindrical structures with a diameter and depth of 10mm. The inserts and sockets on the block surface are fixed together.

[0097] Fifty biomimetic capillary channels with a diameter of 200μm are 3D printed internally to enhance the directional penetration of VOCs.

[0098] (4) Surface treatment:

[0099] Photocatalytic coating: A nitrogen-doped visible light responsive titanium dioxide solution with a thickness of 30 μm and a mass concentration of 3 mg / ml is sprayed onto the outdoor side surface to degrade the emitted VOCs using natural light.

[0100] Hydrophobic layer: The interior side is sprayed with silica aerogel solution with a thickness of 30μm and a mass concentration of 0.85g / ml to prevent water vapor from clogging the micropores.

[0101] Frame surface coating: Apply silica sol to the top, bottom, left and right sides with a thickness of 3mm and a mass concentration of 1.25g / ml, insert and heat-melt, and build up the wall.

[0102] (5) Efficiency decay and stability characteristics

[0103] The initial wall constructed from masonry blocks reduces indoor VOCs by up to 75%, and after a year of adsorption, the reduction in indoor VOCs will stabilize at 65%.

[0104] Table 2 Performance Indicators of Block Walls

[0105]

[0106] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A breathable wall material based on VOCs concentration-controlled gas flow, characterized in that, It is prepared by the following method: 1) Activated carbon fibers with micropore size <2nm and mesopore size 2~50nm or activated carbon fibers with macropore size >50nm are thoroughly stirred with silica particles, titanium dioxide nanoparticles and silica sol to form three mixtures: dry mix 1, dry mix 2 and dry mix 3. In dry mix 1, the mass ratio of activated carbon fibers with micropore size <2nm to silica particles, titanium dioxide nanoparticles and silica sol is 65:15:5:15; in dry mix 2, the mass ratio of activated carbon fibers with pore size 2~50nm to silica particles, titanium dioxide nanoparticles and silica sol is 60:10:10:20; and in dry mix 3, the mass ratio of activated carbon fibers with macropore size >50nm to silica particles, titanium dioxide nanoparticles and silica sol is 55:5:20:

20. 2) The three mixtures obtained are filled into a mold and subjected to three hot-pressing curing processes to obtain building blocks; The hot-press curing molding process is as follows: Fill 2100~2200g of dry mix 1 into the mold, with a filling thickness of 80mm, and hot press it at a temperature of 70℃~80℃, a pressure of 15~20Mpa, and a time of 60~90 seconds to obtain the indoor layer; Fill 1400~1500g of dry mix 2 into the mold, spread it evenly on the top of the inner layer, with a filling thickness of 70mm, and hot press it at a temperature of 70℃~80℃, a pressure of 8~10Mpa, and a time of 60~90 seconds to obtain the middle layer; Fill 700~800g of dry mix 3 into the mold, spread it evenly on top of the middle layer, with a filling thickness of 50mm, and maintain the temperature and pressure at 70℃~80℃ and 3~5Mpa for 0.5h to obtain the outdoor layer; After natural cooling and demolding, the demolded blocks are placed in an oven preheated to 80℃ and heated to 120℃ at a rate of 1~3℃ / min, and held for 2~4 hours to obtain a three-layer structure blank block. The densities of the inner layer, middle layer and outer layer are 0.8~1g / cm³, 0.6~0.8g / cm³ and 0.4~0.6g / cm³, respectively, the pore sizes are 5~10nm, 5~30nm and 30~100nm, respectively, and the porosities are 55~60%, 65~70% and 75~80%, respectively.

2. A method for preparing the breathable wall material according to claim 1, characterized in that, Includes the following steps: 1) Activated carbon fibers with micropore size <2nm and mesopore size 2~50nm or activated carbon fibers with macropore size >50nm are thoroughly stirred with silica particles, titanium dioxide nanoparticles and silica sol to form three mixtures; the diameter of the silica particles is 20nm and the diameter of the titanium dioxide nanoparticles is 1~10nm. 2) The three mixtures are filled into a mold and subjected to three hot-pressing curing processes to obtain blocks.

3. The preparation method according to claim 2, characterized in that, The conditions for thorough stirring in step 1) include: Three types of activated carbon fibers with different pore sizes were added to silica particles and titanium dioxide nanoparticles respectively into a silica sol with a mass fraction of 25%~35% and thoroughly dry-mixed to obtain dry mix 1, dry mix 2 and dry mix 3. The mixture was then dry-mixed in a high-speed mixer for 5–10 min at a speed of 500–800 r / min to form three colloidal mixtures. The silica sol had a particle size of 8~20 nm, a pH of 6~7 and a density of 1.1~1.25 g / cm³. The mass ratio of activated carbon fiber with a micropore size of <2nm to silica particles, titanium dioxide nanoparticles, and silica sol in the dry mixture 1 is 65:15:5:

15. The mass ratio of activated carbon fiber with a pore size of 2~50nm to silica particles, titanium dioxide nanoparticles, and silica sol in the dry mixture 2 is 60:10:10:

20. The mass ratio of activated carbon fiber with a macropore size >50nm to silica particles, titanium dioxide nanoparticles, and silica sol in the dry mixture 3 is 55:5:20:

20.

4. The preparation method according to claim 2, characterized in that, The gel-like dry mixture 1 obtained in step 1) of claim 2 is filled into the mold with a thickness of 80mm. After hot pressing, dry mixture 2 is filled into the mold with a thickness of 70mm. After hot pressing, dry mixture 3 is filled into the mold with a thickness of 50mm and then hot pressed. The gel-like mixture is sequentially filled into the mold with a special structural design in layers and cured by three hot pressings. The design size of the mold is the size of the block. The mold measures 300mm × 200mm × 90mm and has a socket structure. The upper and lower frame surfaces of the mold have four mortise and tenon joints, and the left and right frame surfaces have a total of six mortise and tenon joints. The socket is a cylindrical structure with a diameter of 10mm and a height of 10mm, and the insertion is a cylindrical structure with a diameter of 10mm and a depth of 10mm. The hot-press curing molding process is as follows: Fill 2100~2200g of dry mix 1 into the mold, with a filling thickness of 80mm, and hot press it at a temperature of 70℃~80℃, a pressure of 15~20Mpa, and a time of 60~90 seconds to obtain the indoor layer; Fill 1400~1500g of dry mix 2 into the mold, spread it evenly on the top of the inner layer, with a filling thickness of 70mm, and hot press it at a temperature of 70℃~80℃, a pressure of 8~10Mpa, and a time of 60~90 seconds to obtain the middle layer; Fill 700~800g of dry mix 3 into the mold, spread it evenly on top of the middle layer, with a filling thickness of 50mm, and maintain the temperature and pressure at 70℃~80℃ and 3~5Mpa for 0.5h to obtain the outdoor layer; After natural cooling and demolding, the demolded blocks are placed in an oven preheated to 80℃ and heated to 120℃ at a rate of 1~3℃ / min, and held for 2~4 hours to obtain a three-layer structure blank block. The densities of the inner layer, middle layer and outer layer are 0.8~1g / cm³, 0.6~0.8g / cm³ and 0.4~0.6g / cm³, respectively, the pore sizes are 5~10nm, 5~30nm and 30~100nm, respectively, and the porosities are 55~60%, 65~70% and 75~80%, respectively.

5. The preparation method according to claim 4, characterized in that, The resulting rough blocks are coated on two functional surfaces and four frame surfaces. The functional surface coating consists of nitrogen-doped visible light responsive titanium dioxide on the outer side of the functional surface, with a thickness of 20-30 μm and a mass concentration of 3 mg / ml; and silica aerogel on the inner side of the functional surface, with a thickness of 20-30 μm and a mass concentration of 0.85 g / ml. The frame surface is the top, bottom, left, and right sides of the block. The coating is silica sol with a thickness of 2-3 mm and a mass concentration of 1.25 g / ml, resulting in a breathable wall block with a compressive strength of 3.5-8 MPa, a thermal conductivity of 0.25-0.5 W / (m·K), and a light transmittance of 30-50%.

6. The preparation method according to claim 5, characterized in that, The breathable wall block has four mortise and tenon joints on the upper and lower frame surfaces and six mortise and tenon joints on the left and right frame surfaces. The socket is a cylindrical structure with a diameter of 10mm and a height of 10mm, and the insertion is a cylindrical structure with a diameter of 10mm and a depth of 10mm. The insertion and socket on each block surface are matched and fixed by insertion.

7. The preparation method according to claim 5, characterized in that, The breathable wall blocks are hot-melted at 70℃~80℃ for 10~20s, then fixed to the frame surface and stacked to form a wall.

8. The application of the breathable wall material according to claim 1 in the treatment of VOCs in indoor environments.

Images