Photocatalytic pervious concrete as well as preparation method and application thereof in runoff pollution treatment
By spraying modified g-C3N4-based photocatalyst MnOx onto the surface of permeable concrete, the prepared photocatalytic permeable concrete solved the problem of balancing porosity, permeability, and mechanical properties, achieving a highly efficient pollutant degradation effect. In particular, when the photocatalyst spraying amount was 5 g/L, the degradation efficiency of RhB reached 78.11%, and it also had good cycle stability.
Patent Information
- Application Number
- CN202511338646.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-18
- Publication Date
- 2026-01-09
AI Technical Summary
Existing photocatalytic permeable concrete has difficulty balancing porosity, permeability, mechanical properties, and pollutant degradation properties during its preparation process.
A method of spraying modified g-C3N4-based photocatalyst MnOx was adopted, combined with spraying photocatalyst coating on the surface of permeable concrete, to prepare photocatalytic permeable concrete. By optimizing the component ratio and spraying amount, the permeability and mechanical properties were ensured while improving the degradation effect of pollutants.
While ensuring the water permeability and mechanical properties of the substrate, the degradation performance of liquid and gaseous pollutants was significantly improved. The photocatalyst with a spraying amount of 5 g/L achieved a degradation efficiency of 78.11% for RhB, and maintained a degradation efficiency of over 75% after 6 cycles of testing.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of materials technology, and more specifically, to a photocatalytic permeable concrete, its preparation method, and its application in runoff pollution control. Background Technology
[0002] Urban areas paved with ordinary concrete pavement face potential risks such as severe urban rainwater accumulation and soil erosion. It cannot effectively alleviate the accumulation of pollutants such as heavy metals and macromolecular organic matter, and in severe cases, it may cause pollution of groundwater, rivers, lakes and other water bodies.
[0003] Methods for treating urban runoff pollutants mainly include green roof technology, permeable pavement, rain gardens, bioretention ponds, constructed wetlands, and rainwater storage tanks and treatment plants. Among these, permeable pavement is currently a widely used method. It primarily uses permeable materials such as permeable bricks and permeable concrete to pave urban roads, squares, and other surfaces, allowing rainwater to infiltrate the ground more quickly and reducing surface runoff. Permeable pavement can reduce the concentration of pollutants in runoff while replenishing groundwater and improving the urban hydrological cycle. In the field of urban engineering materials, permeable concrete is also known as porous concrete or aggregate-free concrete. It uses a special preparation process to mix aggregates of specific gradations, cement, admixtures, and water in a specific ratio to create a porous structural material with continuous pores. Compared with traditional ordinary concrete, permeable concrete has excellent air and water permeability, effectively enabling rapid rainwater infiltration, significantly reducing urban flooding, and mitigating the urban heat island effect. Therefore, permeable concrete is considered an important building material for the sustainable development of future cities.
[0004] Studies have shown that permeable concrete pavements containing photocatalytic materials (such as TiO2 and ZnO) can effectively degrade organic pollutants in acidic industrial wastewater and domestic wastewater through the redox reaction of photogenerated charge carriers in the porous medium, providing a novel solution for surface runoff pollution control. However, current photocatalytic permeable concrete preparation technologies have certain limitations. While there are various ways to load photocatalytic materials, it remains difficult to balance porosity, permeability, mechanical properties, and pollutant degradation performance. Summary of the Invention
[0005] To address the aforementioned problems, this invention provides a photocatalytic permeable concrete, its preparation method, and its application in runoff pollution control.
[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:
[0007] In a first aspect, the present invention provides a photocatalytic permeable concrete, which is obtained by spraying a photocatalyst coating onto the surface of permeable concrete;
[0008] The permeable concrete comprises cement at a concentration of 392.5–456.5 kg / m³. 3 Aggregate 1483.7~1570.1kg / m³ 3 Reinforcing agent 19.63~22.83kg / m 3 Water 96.6~138.0kg / m³ 3 The permeable concrete has a bulk density of 2100 kg / m³. 3 ;
[0009] The photocatalyst is g-C3N4 converted to MnO x After modification, the concentration of photocatalyst in the photocatalyst spray coating is 2–8 g / L; the spraying amount of the photocatalyst spray coating is 0.2–0.8 L / m³. 2 .
[0010] In a preferred embodiment, the permeable concrete further includes a water-reducing agent at a concentration of 1.963–2.283 kg / m³. 3 .
[0011] In a preferred embodiment, the concentration of photocatalyst in the photocatalyst coating is 5–8 g / L, and the coating amount is 0.5 L / m². 2 .
[0012] In the preferred embodiment, the water-cement ratio of the permeable concrete is 0.3:1, and the bone-bond ratio is 3.5:1.
[0013] In a preferred embodiment, the preparation method of the photocatalyst includes the following steps:
[0014] 1) Melamine powder was calcined at 700℃ for 2 hours at a heating rate of 5℃ / min. After the reaction was completed, it was cooled to room temperature and ground to obtain g-C3N4 powder.
[0015] 2) Add 15g of g-C3N4 powder and 3.16g of KMnO4 powder to water, stir evenly, and then sonicate for 30 minutes to obtain a suspension.
[0016] 3) Add manganese acetate solution to the suspension, stir at 80℃ for 1 h, wash until neutral and centrifuge, take the precipitate, dry at 80℃ for 12 h to obtain Mn-GCN;
[0017] The molar ratio of KMnO4 to manganese acetate is 3:2.
[0018] 5. The photocatalytic permeable concrete according to claim 4, characterized in that the method for preparing the photocatalyst spray coating includes the following steps:
[0019] S1. Dissolve 5.2g of epoxy resin in 200mL of anhydrous ethanol, then add Mn-GCN, and ultrasonically disperse for 30min to obtain the first dispersion;
[0020] S2. Add 5 mL of 25% ammonia solution to the dispersion, stir magnetically for 10 min, and obtain the second dispersion;
[0021] S3. Slowly add 20 mL of tetraethyl orthosilicate and 8 mL of perfluoroheptadecyltrimethyloxysilane dropwise to the second dispersion. After the addition is complete, continue stirring for 30 min to obtain the third dispersion.
[0022] S4. Add 1.2g of curing agent to the third dispersion and stir magnetically for 3h to obtain a photocatalyst spray coating with a Mn-GCN concentration of 2-8g / L.
[0023] In the preferred embodiment, in step S4, the concentration of Mn-GCN is 5 g / L.
[0024] In a preferred embodiment, the curing agent is 2-ethyl-4-methylimidazole.
[0025] A second aspect of the present invention provides a method for preparing the above-mentioned photocatalytic permeable concrete, comprising the following steps:
[0026] i) Mix the aggregate with 50% water and water-reducing agent, premix for 60 seconds to obtain the first mixture;
[0027] ii) Add cement and permeable concrete reinforcing agent to the first mixture, stir for 60 seconds, then add 50% water and water-reducing agent, stir for 2 minutes to obtain the second mixture;
[0028] iii) Curing the second mixture for 1-2 days yields permeable concrete;
[0029] iv) The photocatalytic coating material was evenly sprayed onto the surface of the permeable concrete and cured for 28 days to obtain the photocatalytic permeable concrete.
[0030] In the preferred embodiment, in steps iii) and / or iv), the curing conditions are as follows: curing is carried out in a standard curing chamber with a temperature of 18–22°C and a relative humidity of 95% or higher.
[0031] A third aspect of the present invention provides an application of the above-mentioned photocatalytic permeable concrete in runoff pollution control.
[0032] The beneficial effects of this invention are as follows:
[0033] The photocatalytic permeable concrete prepared by the method of this invention exhibits the best performance with a photocatalyst coating amount of 5 g / L and a photocatalytic degradation efficiency of 78.11% for RhB by MnPC-s5. After 6 cycles of testing, MnPC-s5 can maintain a degradation efficiency of more than 75% of the initial degradation efficiency, demonstrating good cycle stability.
[0034] This invention combines photocatalytic materials with permeable concrete, thereby improving the degradation performance of permeable concrete for liquid and gaseous pollutants while ensuring the permeability and mechanical properties of the matrix. Detailed Implementation
[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0036] In this invention, unless otherwise stated, scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. Unless otherwise specified, the experimental methods in the embodiments are conventional methods. Where specific conditions are not specified in the embodiments, they should be performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0037] Terminology Explanation
[0038] Water-cement ratio: refers to the weight ratio of water to cement in permeable concrete;
[0039] Bone-cement ratio: refers to the weight ratio of aggregate to cement in permeable concrete.
[0040] Description of experimental materials for this invention
[0041] 1) Aggregate: Limestone crushed stone is used as aggregate, with a particle size of 4.75-9.50 mm;
[0042] 2) Cement: Produced by Shenyang Shanshui Gongyuan Cement Co., Ltd., type: PO42.5;
[0043] 3) Water-reducing agent: Polycarboxylate-based high-efficiency water-reducing agent (SP), produced by Sika Waterproof Materials Co., Ltd.
[0044] 4) Reinforcing agent: Produced by Beijing Puna New Technology Co., Ltd.
[0045] The photocatalyst used in Examples 1-3 of this invention is Mn-GCN, and its preparation method includes the following steps:
[0046] 1) After grinding a certain amount of melamine evenly with a mortar and pestle, place it in a covered crucible and calcine it at 700℃ for 2 hours in a muffle furnace with a heating rate of 5℃ / min. After cooling to room temperature, take it out and grind it evenly with a mortar and pestle to obtain the final powder g-C3N4, denoted as GCN.
[0047] 2) Weigh 15g of GCN powder and 3.16g of KMnO4 powder and add them to deionized water. Stir well and ultrasonically disperse for 30min to obtain 150mL of suspension.
[0048] 3) Add 150 mL of manganese acetate solution to the suspension, with a molar ratio of KMnO4 powder to manganese acetate of 3:2. Stir at 80℃ for 1 h, wash until neutral, centrifuge, and dry in a forced-air drying oven at 80℃ for 12 h. Grind the dried solid into powder. x Modified g-C3N4 yields a photocatalyst, denoted as Mn-GCN.
[0049] Example 1: Spray coating method (2g / LMn-GCN)
[0050] Permeable concrete contains 433.0 kg / m³ of cement. 3 Aggregate 1515.5kg / m³ 3 21.65 kg / m² of reinforcing agent 3 Water-reducing agent 2.165 kg / m 3 Water 129.9kg / m 3 .
[0051] The preparation method of photocatalyst spray coating includes the following steps:
[0052] S1. Dissolve 5.2g of epoxy resin in 200mL of anhydrous ethanol, then add Mn-GCN, and ultrasonically disperse for 30min to obtain the first dispersion;
[0053] S2. Add 5 mL of 25% ammonia solution to the dispersion, stir magnetically for 10 min, and obtain the second dispersion;
[0054] S3. Slowly add 20 mL of tetraethyl orthosilicate and 8 mL of perfluoroheptadecyltrimethyloxysilane dropwise to the second dispersion. After the addition is complete, continue stirring for 30 min to obtain the third dispersion.
[0055] S4. Add 1.2g of 2-ethyl-4-methylimidazolium as a curing agent to the third dispersion, and stir magnetically for 3h to obtain a photocatalyst spray coating with a Mn-GCN concentration of 2g / L.
[0056] The preparation method of photocatalytic permeable concrete includes the following steps:
[0057] i) According to the raw material ratio provided in this embodiment, the aggregate, 50% water and water-reducing agent are put into the mixer and premixed for 60 seconds to fully wet the surface of the aggregate and obtain the first mixture;
[0058] ii) Add cement and permeable concrete reinforcing agent to the first mixture, stir for 60 seconds to ensure uniform distribution of dry materials, then add the remaining water and water-reducing agent, stir for 2 minutes to make the mixture uniform, and obtain the second mixture;
[0059] iii) Pour the second mixture into the mold in four batches, tamping it thoroughly each time. Finally, use a vibrating table to ensure that the aggregate is evenly distributed. Then, place it in a standard curing box at 20±2℃ and relative humidity of 95% or higher for 1 to 2 days to obtain permeable concrete.
[0060] iv) The photocatalytic coating is evenly sprayed onto the surface of the permeable concrete and then placed in a standard curing chamber at 20±2℃ and relative humidity of 95% or higher for 28 days to obtain photocatalytic permeable concrete, denoted as MnPC-s2.
[0061] In this embodiment, three photocatalytic permeable concrete specimens of different specifications were prepared according to the above method: a 100mm×100mm×100mm cube specimen, denoted as 1-MnPC-s2, used for porosity, permeability coefficient, and compressive strength testing; a 100mm×100mm×400mm prism specimen, denoted as 2-MnPC-s2, used for flexural strength testing; and a prism specimen with dimensions of 100mm×100mm×400mm, used for flexural strength testing; and a prism specimen with dimensions of 100mm×100mm×400mm. The disc-shaped test block, designated 3-MnPC-s2, is used for adsorption and photocatalytic performance testing.
[0062] Example 2: Spray coating method (5g / LMn-GCN)
[0063] Permeable concrete contains 433.0 kg / m³ of cement. 3 Aggregate 1515.5kg / m³ 3 21.65 kg / m² of reinforcing agent 3 Water-reducing agent 2.165 kg / m 3 Water 129.9kg / m 3 .
[0064] The preparation method of photocatalyst spray coating includes the following steps:
[0065] S1. Dissolve 5.2g of epoxy resin in 200mL of anhydrous ethanol, then add Mn-GCN, and ultrasonically disperse for 30min to obtain the first dispersion;
[0066] S2. Add 5 mL of 25% ammonia solution to the dispersion, stir magnetically for 10 min, and obtain the second dispersion;
[0067] S3. Slowly add 20 mL of tetraethyl orthosilicate and 8 mL of perfluoroheptadecyltrimethyloxysilane dropwise to the second dispersion. After the addition is complete, continue stirring for 30 min to obtain the third dispersion.
[0068] S4. Add 1.2g of 2-ethyl-4-methylimidazolium as a curing agent to the third dispersion, and stir magnetically for 3h to obtain a photocatalyst spray coating with a Mn-GCN concentration of 5g / L.
[0069] The preparation method of photocatalytic permeable concrete includes the following steps:
[0070] i) According to the raw material ratio provided in this embodiment, the aggregate, 50% water and water-reducing agent are put into the mixer and premixed for 60 seconds to fully wet the surface of the aggregate and obtain the first mixture;
[0071] ii) Add cement and permeable concrete reinforcing agent to the first mixture, stir for 60 seconds to ensure uniform distribution of dry materials, then add the remaining water and water-reducing agent, stir for 2 minutes to make the mixture uniform, and obtain the second mixture;
[0072] iii) Pour the second mixture into the mold in four batches, tamping it thoroughly each time. Finally, use a vibrating table to ensure that the aggregate is evenly distributed. Then, place it in a standard curing box at 20±2℃ and relative humidity of 95% or higher for 1 to 2 days to obtain permeable concrete.
[0073] iv) The photocatalytic coating is evenly sprayed onto the surface of the permeable concrete and then placed in a standard curing chamber at 20±2℃ and relative humidity of 95% or higher for 28 days to obtain photocatalytic permeable concrete, denoted as MnPC-s5.
[0074] In this embodiment, three photocatalytic permeable concrete specimens of different specifications were prepared according to the above method: a 100mm×100mm×100mm cube specimen, denoted as 1-MnPC-s5, for testing porosity, permeability coefficient, and compressive strength; a 100mm×100mm×400mm prism specimen, denoted as 2-MnPC-s5, for testing flexural strength; and a prism specimen with dimensions of [missing information - likely a missing section]. The disc-shaped test block, designated 3-MnPC-s5, is used for adsorption and photocatalytic performance testing.
[0075] Example 3: Spray coating method (8g / LMn-GCN)
[0076] Permeable concrete contains 433.0 kg / m³ of cement. 3 Aggregate 1515.5kg / m³ 3 21.65 kg / m² of reinforcing agent 3 Water-reducing agent 2.165 kg / m 3Water 129.9kg / m 3 .
[0077] The preparation method of photocatalyst spray coating includes the following steps:
[0078] S1. Dissolve 5.2g of epoxy resin in 200mL of anhydrous ethanol, then add Mn-GCN, and ultrasonically disperse for 30min to obtain the first dispersion;
[0079] S2. Add 5 mL of 25% ammonia solution to the dispersion, stir magnetically for 10 min, and obtain the second dispersion;
[0080] S3. Slowly add 20 mL of tetraethyl orthosilicate and 8 mL of perfluoroheptadecyltrimethyloxysilane dropwise to the second dispersion. After the addition is complete, continue stirring for 30 min to obtain the third dispersion.
[0081] S4. Add 1.2g of 2-ethyl-4-methylimidazolium as a curing agent to the third dispersion, and stir magnetically for 3h to obtain a photocatalyst spray coating with a Mn-GCN concentration of 8g / L.
[0082] The preparation method of photocatalytic permeable concrete includes the following steps:
[0083] i) According to the raw material ratio provided in this embodiment, the aggregate, 50% water and water-reducing agent are put into the mixer and premixed for 60 seconds to fully wet the surface of the aggregate and obtain the first mixture;
[0084] ii) Add cement and permeable concrete reinforcing agent to the first mixture, stir for 60 seconds to ensure uniform distribution of dry materials, then add the remaining water and water-reducing agent, stir for 2 minutes to make the mixture uniform, and obtain the second mixture;
[0085] iii) Pour the second mixture into the mold in four batches, tamping it thoroughly each time. Finally, use a vibrating table to ensure that the aggregate is evenly distributed. Then, place it in a standard curing box at 20±2℃ and relative humidity of 95% or higher for 1 to 2 days to obtain permeable concrete.
[0086] iv) The photocatalytic coating is evenly sprayed onto the surface of the permeable concrete and then placed in a standard curing chamber at 20±2℃ and relative humidity of 95% or higher for 28 days to obtain photocatalytic permeable concrete, denoted as MnPC-s8.
[0087] In this embodiment, three types of photocatalytic permeable concrete specimens of different specifications were prepared according to the above method: a 100mm×100mm×100mm cubic specimen, denoted as 1-MnPC-s8, used for porosity, permeability coefficient, and compressive strength testing; a 100mm×100mm×400mm prism specimen, denoted as 2-MnPC-s8, used for flexural strength testing; and a prism specimen with dimensions of 100mm×100mm×400mm, used for flexural strength testing; and a prism specimen with dimensions of 100mm×100mm×400mm. The disc-shaped test block, designated 3-MnPC-s8, is used for adsorption and photocatalytic performance testing.
[0088] Comparative Example 1: Ordinary permeable concrete
[0089] Permeable concrete contains 433.0 kg / m³ of cement. 3 Aggregate 1515.5kg / m³ 3 21.65 kg / m² of reinforcing agent 3 Water-reducing agent 2.165 kg / m 3 Water 129.9kg / m 3 .
[0090] The preparation method of permeable concrete includes the following steps:
[0091] Accurately weigh the cement, aggregate, permeable concrete reinforcing agent, water, and water-reducing agent according to the raw material proportions provided in this comparison ratio. Add the aggregate, 50% of the water, and the water-reducing agent to the mixer and premix for 60 seconds to fully wet the aggregate surface. Add the cement and permeable concrete reinforcing agent and continue mixing for 60 seconds to ensure even distribution of dry materials. Add the remaining water and water-reducing agent and mix for 2 minutes to achieve a homogeneous mixture. Pour the mixture into the mold in four batches, tamping thoroughly each time, and finally use a vibrating table to ensure even aggregate distribution. Cover its surface with plastic wrap and place it in an indoor environment with a temperature of 20℃±5℃ and a relative humidity of more than 50%. During the placement of the test block, avoid vibration and impact. Place the test piece in the curing room and let it stand for 1 to 2 days. After demolding, label it and transfer it to a standard curing room with a temperature of 20℃±2℃ and a relative humidity of more than 95%. After waiting for 28 days, take it out to obtain permeable concrete, which is denoted as CN.
[0092] In this comparative example, three photocatalytic permeable concrete specimens of different specifications were prepared according to the above method: a 100mm×100mm×100mm cube specimen, denoted as 1-CN, used for porosity, permeability coefficient, and compressive strength testing; a 100mm×100mm×400mm prism specimen, denoted as 2-CN, used for flexural strength testing; and a prism specimen with dimensions of [missing information - likely a missing section]. The disc-shaped test block, designated 3-CN, is used for testing adsorption and photocatalytic performance.
[0093] Comparative Example 2: Spray coating method (5g / LGCN)
[0094] Permeable concrete contains 433.0 kg / m³ of cement. 3 Aggregate 1515.5kg / m³ 3 21.65 kg / m² of reinforcing agent 3 Water-reducing agent 2.165 kg / m 3 Water 129.9kg / m 3 .
[0095] The preparation method of photocatalyst includes the following steps:
[0096] A certain amount of melamine was thoroughly ground evenly using a mortar and pestle and placed in a covered crucible. The crucible was then placed in a muffle furnace and calcined at 700°C for 2 hours at a heating rate of 5°C / min. After cooling to room temperature, the calcined melamine was removed and ground evenly using a mortar and pestle to obtain the final powdered g-C3N4, denoted as GCN.
[0097] The preparation method of photocatalyst spray coating includes the following steps:
[0098] S1. Dissolve 5.2g of epoxy resin in 200mL of anhydrous ethanol, then add GCN, and ultrasonically disperse for 30min to obtain the first dispersion;
[0099] S2. Add 5 mL of 25% ammonia solution to the dispersion, stir magnetically for 10 min, and obtain the second dispersion;
[0100] S3. Slowly add 20 mL of tetraethyl orthosilicate and 8 mL of perfluoroheptadecyltrimethyloxysilane dropwise to the second dispersion. After the addition is complete, continue stirring for 30 min to obtain the third dispersion.
[0101] S4. Add 1.2g of 2-ethyl-4-methylimidazolium as a curing agent to the third dispersion, and stir magnetically for 3h to obtain a photocatalyst spray coating with a Mn-GCN concentration of 8g / L.
[0102] The preparation method of photocatalytic permeable concrete includes the following steps:
[0103] i) According to the raw material ratio provided in this embodiment, the aggregate, 50% water and water-reducing agent are put into the mixer and premixed for 60 seconds to fully wet the surface of the aggregate and obtain the first mixture;
[0104] ii) Add cement and permeable concrete reinforcing agent to the first mixture, stir for 60 seconds to ensure uniform distribution of dry materials, then add the remaining water and water-reducing agent, stir for 2 minutes to make the mixture uniform, and obtain the second mixture;
[0105] iii) Pour the second mixture into the mold in four batches, tamping it thoroughly each time. Finally, use a vibrating table to ensure that the aggregate is evenly distributed. Then, place it in a standard curing box at 20±2℃ and relative humidity of 95% or higher for 1 to 2 days to obtain permeable concrete.
[0106] iv) The photocatalytic coating is evenly sprayed onto the surface of the permeable concrete and then placed in a standard curing chamber at 20±2℃ and relative humidity of 95% or higher for 28 days to obtain photocatalytic permeable concrete, denoted as GPC-s5.
[0107] The permeable concrete GPC-s5 prepared according to the above method in this comparative example has the following dimensions: The disc-shaped test blocks are used for testing adsorption and photocatalytic performance.
[0108] Comparative Example 3: Internal control method (5g / LMn-GCN)
[0109] Based on the ordinary concrete components provided in Comparative Example 1, this comparative example of photocatalytic permeable concrete was prepared by replacing part of the cement with Mn-GCN, while the remaining components were exactly the same as those in Comparative Example 1, resulting in a photocatalytic permeable concrete with an internal Mn-GCN content of 5 wt%.
[0110] The preparation method of photocatalytic permeable concrete includes the following steps:
[0111] i) According to the raw material ratio provided in this embodiment, the aggregate, 50% water and water-reducing agent are put into the mixer and premixed for 60 seconds to fully wet the surface of the aggregate and obtain the first mixture;
[0112] ii) Add Mn-GCN, cement and permeable concrete reinforcing agent to the first mixture, stir for 60 seconds to ensure uniform distribution of dry materials, then add the remaining water and water-reducing agent, stir for 2 minutes to make the mixture reach a homogeneous state, and obtain the second mixture;
[0113] iii) Pour the second mixture into the mold in four batches, tamping it thoroughly each time. Finally, use a vibrating table to ensure uniform aggregate distribution. Cover the surface with plastic wrap and place it in an indoor environment with a temperature of 20±5℃ and a relative humidity of more than 50%. Avoid vibration and impact during the placement of the test blocks. Place the test specimens in the curing room and let them stand for 1 to 2 days. After demolding, label them and transfer them to a standard curing room with a temperature of 20±2℃ and a relative humidity of more than 95%. After 28 days, take them out to obtain photocatalytic permeable concrete, denoted as MnPC-i5.
[0114] The permeable concrete MnPC-i5 prepared according to the above method in this comparative example has the following dimensions: The disc-shaped test blocks are used for testing adsorption and photocatalytic performance.
[0115] Experimental Example 1: Photocatalytic performance test
[0116] 1. Testing Method
[0117] This invention evaluates the photocatalytic performance of permeable concrete using Rhodamine B (RhB) as the target pollutant. Photocatalytic permeable concrete test blocks were removed from the curing chamber, cleaned, and dried in a forced-air drying oven at 60°C for 24 hours. The surface dust was then cleaned with a brush to avoid affecting the absorbance of the Rhodamine B (RhB) solution. 350 mL of a 20 mg / L RhB solution was poured into a 500 mL beaker, and after pH adjustment, a container of [size missing] was placed in the beaker. The photocatalytic permeable concrete specimen was placed in a beaker, and the solution was stirred with a magnetic stirrer to simulate the scouring effect of water flow in runoff. Under light-protected conditions, the mixture was magnetically stirred for 30 minutes to reach adsorption-desorption equilibrium. The xenon lamp was then turned on, and the reaction was carried out under visible light irradiation for 120 minutes. The resulting reaction solution was filtered through a 0.22 μm disposable aqueous filter membrane to obtain a clear solution, which was then stored in a centrifuge tube for testing. The photocatalytic degradation efficiency was calculated according to formula (1).
[0118]
[0119] In the formula, C t Ct represents the concentration of the RhB solution at time t (mg / L); C0 represents the initial concentration of the RhB solution at time t (mg / L).
[0120] 2. Test Results
[0121] The photocatalytic degradation capabilities of 3-MnPC-s2, 3-MnPC-s5, 3-MnPC-s8, 3-CN, 3-GPC-s5 and 3-MnPC-i5 were tested using the above method, and the test results are shown in Table 1.
[0122] Table 1. Photocatalytic performance test results
[0123] test block Photocatalytic degradation efficiency (%) <![CDATA[3-MnPC-s2]]> 63.36 <![CDATA[3-MnPC-s5]]> 78.11 <![CDATA[3-MnPC-s8]]> 76.61 3-CN 12.98 <![CDATA[GPC-s5]]> 45.59 <![CDATA[MnPC-i5]]> 36.01
[0124] As shown in Table 1, the experimental results show that the photocatalytic degradation rate of the photocatalytic permeable concrete prepared in Examples 1-3 of the present invention is significantly higher than that of ordinary permeable concrete, photocatalytic permeable concrete prepared by the internal reference method, and photocatalytic permeable concrete coated with a photocatalyst coating at a concentration of 5 g / L GCN.
[0125] Cyclic stability tests were conducted on MnPC-s5, which exhibited the best photocatalytic degradation performance of RhB. After six cycles of degradation, MnPC-s5 maintained a degradation efficiency of 58.72% for RhB after 120 min of visible light irradiation, still above 75% of the initial degradation efficiency.
[0126] Experimental Example 2: Porosity and permeability testing
[0127] 1. Porosity testing methods
[0128] According to the requirements of the "Technical Specification for Permeable Cement Concrete Pavement" (CJJ / T-2009), the porosity of permeable concrete should be no less than 10%. Before testing, a 100mm×100mm×100mm permeable concrete specimen was cured and placed in a 60℃ drying oven for 24 hours. After it was completely dried, it was taken out and weighed, and the mass was recorded as m1. The dried permeable concrete specimen was completely immersed in a container filled with water, and the sides of the specimen were gently tapped with a rubber mallet to allow water to penetrate into the pores of the permeable concrete. This was maintained for 1 hour, and then the specimen was inverted in the water. This process was repeated, and the specimen was left to stand for 24 hours. The mass of the permeable concrete in the water was then weighed and recorded as m2. The porosity of the permeable concrete was calculated using formula (2).
[0129]
[0130] In the formula, P is the porosity (%) of the permeable concrete cube specimen; ρ w The density of water (g / cm³) 3 v represents the volume (cm³) of the permeable concrete calculated based on the standard dimensions of the mold used for molding. 3 m1 is the mass (g) of the specimen after drying in a 60℃ drying oven for 24 hours; m2 is the mass (g) of the specimen measured in water after immersion for 24 hours.
[0131] 2. Permeability Coefficient Test Method
[0132] Moistened permeable concrete measuring 100mm×100mm×100mm was placed in a 60℃ forced-air drying oven for 24 hours until constant weight was achieved. The specimen was then placed in a permeable device, and the sides were sealed to prevent leakage. Water was added to the square container during the experiment, and the addition was stopped when the water level exceeded the mark H on the container. The time t when the liquid level dropped to 0mm was recorded. The permeability coefficient (k) was calculated according to formula (3). Each specimen was tested three times, and the average value was taken as the final permeability coefficient.
[0133]
[0134] In the formula, k is the permeability coefficient of the permeable concrete cube specimen (mm / s); H is the water injection height (mm); and t is the time (s) when the liquid level drops to 0mm.
[0135] 3. Test Results
[0136] The porosity and permeability coefficient of 1-MnPC-s2, 1-MnPC-s5, 1-MnPC-s8 and 1-CN were tested using the above method, and the test results are shown in Table 2.
[0137] Table 2. Test results of porosity and permeability coefficient
[0138] Specimen Porosity (%) Permeability coefficient (mm / s) <![CDATA[1-MnPC-s2]]> 11.7 2.92 <![CDATA[1-MnPC-s5]]> 11.65 2.88 <![CDATA[1-MnPC-s8]]> 10.96 2.71 1-CN 12.38 3.06
[0139] Experimental Example 3: Mechanical property testing
[0140] 1. Compressive strength test method
[0141] The compressive strength of permeable concrete was tested according to the "National Standard of the People's Republic of China: Test Methods for Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the test results were multiplied by a coefficient of 0.95 for calculation. After the porosity and permeability tests of permeable concrete were completed, the test blocks were placed in a 60℃ forced-air drying oven and dried for 24 hours. After the permeable concrete was completely dry, its size and shape were checked and found to be basically in line with the requirements before the experiment was conducted. The side of the permeable concrete during molding was used as the bearing surface. The center of gravity of the test block should be aligned with the center of the upper and lower bearing plates to prevent the specimen from being subjected to uneven pressure. Before applying the load, the contact distance between the upper and lower bearing plates and the permeable concrete was manually adjusted so that the surface of the permeable concrete test block was flat and just in contact with the upper and lower bearing plates. The pressure testing machine was operated by manually rotating the valve to lower the pressure plate. The speed was slowed down when it approached the upper surface of the specimen, and the valve was stopped when the upper pressure plate contacted the surface of the specimen. Turn the machine throttle clockwise. The loading process should be uniform and continuous, with a loading rate of 0.3 to 0.5 MPa / s. When the specimen is compressed until it fails, click the stop button, turn the throttle counterclockwise, and record the maximum load F. The compressive strength is calculated according to formula (4).
[0142]
[0143] In the formula, f cc F represents the compressive strength (MPa) of the permeable concrete cube specimen; F represents the maximum load at which the specimen fails (N); A represents the area of the specimen subjected to the load (mm²). 2 ).
[0144] 2. Flexural Strength Test Method
[0145] The flexural strength of permeable concrete was tested according to the "National Standard of the People's Republic of China for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the test results were multiplied by a coefficient of 0.85 for calculation. Appropriately sized rigid steel cylinders and plates were used as experimental supports and structural supports for applying external forces. One end of the support was a fixed hinge support, and the rest were rolling hinge supports. The specimens cured for 28 days were removed from the curing chamber, their surfaces were wiped, and trisecting lines were marked on the surface with a thin rope. The specimens were placed stably on the support of the testing machine and aligned with the center. The testing machine was operated by machine control to lower the pressure plate, slowing down when it approached the upper surface of the rigid steel plate, and stopping when the upper pressure plate contacted the surface of the rigid steel plate. A suitable loading method was selected in the control panel window, with the rate controlled at 0.5 MPa / s. When the specimen was subjected to external force until failure, the stop button was clicked and the maximum load F was recorded. The flexural strength was calculated according to formula (5).
[0146]
[0147] In the formula, f cl 1 is the flexural strength (MPa) of the permeable concrete column specimen; F is the maximum load at which the specimen fails (N); l is the span between supports (mm); b is the width of the specimen section (mm); h is the height of the specimen section (mm).
[0148] 3. Test Results
[0149] The compressive strength of 1-MnPC-s2, 1-MnPC-s5, 1-MnPC-s8 and 1-CN were tested using the above method, and the flexural strength of 2-MnPC-s2, 2-MnPC-s5, 2-MnPC-s8 and 2-CN were tested. The test results are shown in Table 3.
[0150] Table 3. Test results of mechanical properties of permeable concrete
[0151]
[0152]
[0153] According to the "Technical Specification for Permeable Cement Concrete Pavement" (CJJ / T-2009), permeable concrete should have a porosity ≥10% after 28 days, a permeability coefficient ≥0.5 mm / s, a compressive strength ≥20 MPa, and a flexural strength ≥2.5 MPa. The test results of Examples 2-3 show that the porosity and permeability coefficient of the photocatalytic permeable concrete prepared in Examples 1-3 of this invention are slightly lower than those of ordinary permeable concrete, but still meet the specification requirements (porosity ≥10%). Compared to ordinary permeable concrete, the mechanical properties of the photocatalytic permeable concrete prepared in Examples 1-3 of this invention are all improved, and these properties increase with the increase of photocatalyst content. The photocatalytic coating inhibits microcrack propagation by forming a continuous network structure, while simultaneously penetrating to the aggregate interface transition zone to improve its internal bonding strength.
[0154] The photocatalytic permeable concrete provided by this invention enriches RhB molecules at the solid-liquid interface through the physical adsorption of a porous framework. The photocatalytic degradation of RhB mainly occurs on the surface of the permeable concrete, while the internal structure primarily functions as an adsorbent. MnO on the Mn-GCN surface... x Nanoparticles via Mn 4+ and Mn 3+ The variable valence cycle significantly improves photocatalytic efficiency. Under photoexcitation, Mn 4+ Captured electrons reduced to Mn 3+ This promotes carrier separation and reduces recombination, while Mn 3+ The oxidation reactants maintain the cycle. The narrow bandgap (1.76 eV) of Mn-GCN expands the visible light response range. During photocatalysis, charge separation occurs in Mn-GCN, and electrons and holes recombine through the built-in electric field to generate active free radicals (·O2). - RhB is degraded by ·OH.
[0155] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A photocatalytic permeable concrete, characterized in that, It is obtained by spraying a photocatalyst coating onto the surface of permeable concrete; the permeable concrete comprises 392.5–456.5 kg / m³ of cement. 3 Aggregate 1483.7~1570.1kg / m³ 3 Reinforcing agent 19.63~22.83kg / m 3 Water content: 96.6–138.0 kg / m³ 3 The permeable concrete has a bulk density of 2100 kg / m³. 3 ; The photocatalyst is g-C3N4 converted to MnO x After modification, the concentration of photocatalyst in the photocatalyst spray coating is 2–8 g / L; the spraying amount of the photocatalyst spray coating is 0.2–0.8 L / m³. 2 .
2. The photocatalytic permeable concrete according to claim 1, characterized in that, The concentration of photocatalyst in the photocatalyst coating is 5–8 g / L, and the coating amount is 0.5 L / m². 2 .
3. The photocatalytic permeable concrete according to claim 1, characterized in that, The permeable concrete has a water-cement ratio of 0.3:1 and a binder-bone ratio of 3.5:
1.
4. The photocatalytic permeable concrete according to claim 1, characterized in that, The preparation method of the photocatalyst includes the following steps: 1) Melamine powder was calcined at 700℃ for 2 hours at a heating rate of 5℃ / min. After the reaction was completed, it was cooled to room temperature and ground to obtain g-C3N4 powder. 2) Add 15g of g-C3N4 powder and 3.16g of KMnO4 powder to water, stir evenly, and then sonicate for 30 minutes to obtain a suspension. 3) Add manganese acetate solution to the suspension, stir at 80℃ for 1 h, wash until neutral and centrifuge, take the precipitate, dry at 80℃ for 12 h to obtain Mn-GCN; The molar ratio of KMnO4 to manganese acetate is 3:
2.
5. The photocatalytic permeable concrete according to claim 4, characterized in that, The method for preparing the photocatalyst spray coating includes the following steps: S1. Dissolve 5.2g of epoxy resin in 200mL of anhydrous ethanol, then add Mn-GCN, and ultrasonically disperse for 30min to obtain the first dispersion; S2. Add 5 mL of 25% ammonia solution to the dispersion, stir magnetically for 10 min, and obtain the second dispersion; S3. Slowly add 20 mL of tetraethyl orthosilicate and 8 mL of perfluoroheptadecyltrimethyloxysilane dropwise to the second dispersion. After the addition is complete, continue stirring for 30 min to obtain the third dispersion. S4. Add 1.2g of curing agent to the third dispersion and stir magnetically for 3h to obtain a photocatalyst spray coating with a Mn-GCN concentration of 2-8g / L.
6. The photocatalytic permeable concrete according to claim 5, characterized in that, In step S4, the concentration of Mn-GCN is 5 g / L.
7. The photocatalytic permeable concrete according to claim 1, characterized in that, The curing agent is 2-ethyl-4-methylimidazole.
8. A method for preparing photocatalytic permeable concrete according to any one of claims 1 to 7, characterized in that, Includes the following steps: i) Mix the aggregate with 50% water and water-reducing agent, premix for 60 seconds to obtain the first mixture; ii) Add cement and permeable concrete reinforcing agent to the first mixture, stir for 60 seconds, then add 50% water and water-reducing agent, stir for 2 minutes to obtain the second mixture; iii) Curing the second mixture for 1-2 days yields permeable concrete; iv) The photocatalytic coating material was evenly sprayed onto the surface of the permeable concrete and cured for 28 days to obtain the photocatalytic permeable concrete.
9. The method for preparing photocatalytic permeable concrete according to claim 8, characterized in that, In steps iii) and / or iv), the curing conditions are as follows: curing is carried out in a standard curing chamber with a temperature of 18–22°C and a relative humidity of 95% or higher.
10. The application of the photocatalytic permeable concrete according to any one of claims 1 to 7 in runoff pollution control.