Preparation method of in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete

Abstract

This invention discloses a method for preparing an in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete. The method includes using sodium ferric ethylenediaminetetraacetate (EDTA) as a core precursor, and encapsulating calcium peroxide on its surface through an in-situ reaction to form a composite precursor of calcium peroxide encapsulating EDTA; directional hydrolysis of tetraethyl orthosilicate (TEOS) to form a thin layer of silica on the surface of the composite precursor; subsequent calcination under an inert gas to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica; and finally, grafting with aminosilane to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica with surface-grafted aminosilane. The composite material prepared by this method can achieve continuous and efficient bactericidal action in concrete while increasing nucleation sites, promoting hydration, and effectively improving the early strength and durability of concrete.

Description

Technical Field

[0001] This invention relates to the field of concrete nanocomposite materials technology, specifically to a method for preparing an in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete. Background Technology

[0002] The preparation and application of novel nanomaterials hold immense potential in the green building industry. As the industry's requirements for reducing carbon emissions and achieving energy conservation and environmental protection become increasingly stringent, the selection of building materials becomes crucial to achieving these goals. The application of nanomaterials in the concrete field has been extensively researched and practiced. For example, nanoparticles such as nano-silica and nano-alumina can be used as concrete reinforcing materials to improve the mechanical properties and durability of concrete. Nano-graphene can be used to enhance the electrical conductivity and crack resistance of concrete.

[0003] Single-atom nanozymes are nanomaterials with unique properties, primarily characterized by highly stable single-atom active centers and tunability. These active centers can mimic the catalytic function of natural enzymes, exhibiting high efficiency, high selectivity, and controllability. Through appropriate regulation, the structure and catalytic performance of single-atom nanozymes can be optimized and adjusted to meet diverse application requirements, demonstrating great potential as next-generation nanozymes. Single-atom nanozymes have wide applications in various fields, with catalysis being one of the most important. They can catalyze various chemical reactions, such as oxygen reduction, hydrogenation, and oxidation, exhibiting catalytic efficiency and enzymatic reaction kinetics similar to natural enzymes. Their high efficiency and high selectivity make them important candidate materials for green catalysis. Furthermore, single-atom nanozymes have shown potential applications in energy conversion, environmental protection, and biomedicine. However, no reports have yet been found regarding their application in the concrete industry. Summary of the Invention

[0004] 1. The technical problem to be solved:

[0005] To address the aforementioned technical problems, this invention provides a method for preparing an in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete. This method involves coating the surface of a single-atom iron nanoenzyme with porous calcium peroxide and porous silica to form a three-layer core-shell structure nanocomposite material, and then modifying its surface with aminosilane to impart good compatibility between organic and inorganic materials.

[0006] 2. Technical Solution:

[0007] A method for preparing in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete, characterized by comprising the following steps:

[0008] Step 1: Mix sodium iron ethylenediaminetetraacetate (NaFeEDTA) and calcium nitrate in a certain proportion, add a certain concentration of ammonia solution and stir to dissolve, add hydrogen peroxide dropwise and stir for a period of time to obtain a solution of sodium iron ethylenediaminetetraacetate precursor material coated with calcium peroxide.

[0009] Step 2: Slowly add a certain amount of tetraethyl orthosilicate solution to the precursor material solution obtained in Step 1, stir, and stop hydrolyzing at room temperature for a period of time. After freeze drying and grinding, a three-layer core-shell structure composite material of sodium iron ethylenediaminetetraacetate / calcium peroxide / silica is obtained.

[0010] Step 3: The three-layer core-shell composite material obtained in Step 2 is calcined in nitrogen at a certain temperature to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica.

[0011] Step 4: Disperse the composite material obtained in Step 3 in ethanol, add a certain amount of aminosilane, stir for a period of time, filter and dry to obtain a three-layer core-shell structure composite material of single-atom iron nanozyme / porous calcium peroxide / porous silica with aminosilane grafted on the surface.

[0012] Furthermore, in step one, the mass ratio of sodium iron ethylenediaminetetraacetate (NaFeEDTA) to calcium nitrate is 1:(0.5-0.1).

[0013] Furthermore, in step one, the concentration of ammonia is 0.01–0.5 mol / L; the concentration of hydrogen peroxide is 0.01–0.5 mol / L; and the stirring time is 1–6 h.

[0014] Furthermore, in step two, the mass ratio of the calcium peroxide-coated sodium iron ethylenediaminetetraacetate precursor material to solid tetraethyl orthosilicate is 1:(0.5-0.1), and the hydrolysis time is 12-24 h.

[0015] Furthermore, in step three, the calcination temperature is 300–350℃, and the calcination time is 1–4 hours.

[0016] Furthermore, in step four, the aminosilane is one of 3-aminopropyltrimethoxysilane, vinyltrimethoxysilane, and methacryloxysilane.

[0017] Furthermore, in step four, the mass ratio of aminosilane to the composite material obtained in step three dispersed in ethanol is (0.01–0.05):1, and the stirring time is 12–24 h.

[0018] 3. Beneficial effects:

[0019] (1) The nanocomposite material prepared by this method has strong catalytic activity under alkaline conditions. Since the pore solution of concrete is strongly alkaline, in order to reduce the influence of its alkalinity on the enzyme activity of single-atom nanozymes, the core-shell structure designed in this invention encapsulates the single-atom nanozymes in a protective shell, which can provide an additional protective layer and reduce its direct contact with the strongly alkaline environment; secondly, by introducing organic molecular amine groups containing alkaline groups, additional proton buffering capacity is provided to protect the active site of the enzyme from the influence of the alkaline environment.

[0020] (2) The nanocomposite material prepared in this invention exhibits excellent reinforcing effects in concrete. The nanocomposite material prepared in this invention incorporates elements such as silicon, calcium, and iron. The addition of these elements optimizes the microstructure of concrete. Silane chemical modification enhances the hydrophilicity and hydrophobicity of the concrete surface, improves the interfacial bonding force between cement particles and aggregates, thereby enhancing the density and uniformity of the concrete. This optimized microstructure helps form more hydration products, such as calcium silicate hydrate (CSH gel), during the concrete setting and hardening process, which is a major source of concrete strength. Furthermore, the addition of amino and silane chemical modifications provides more nucleation sites in cement-based materials, accelerating the cement hydration reaction, improving its early strength and durability.

[0021] (3) The nanocomposite material prepared by this invention exhibits excellent antibacterial properties. The inner layer of calcium peroxide releases oxygen slowly and continuously, which is then activated in situ by the core single-atom iron nanozyme to form various types of reactive oxygen species (ROS). ROS possess strong oxidizing properties, rapidly destroying the cell walls and cell membranes of bacteria, fungi, and other microorganisms, thus blocking their life activities and achieving excellent bactericidal effects. Therefore, the nanocomposite material prepared by this method not only provides an intrinsic and efficient antibacterial mechanism for concrete materials but also significantly enhances the material's self-cleaning ability and resistance to bio-erosion. Furthermore, this antibacterial mechanism, driven by both calcium peroxide and single-atom iron nanozyme, does not rely on external chemical disinfectants, avoiding potential environmental pollution and the side effects of chemical drugs, making it an environmentally friendly and sustainable antibacterial strategy.

[0022] In summary, the method for preparing nanocomposites, based on the synergistic effect of the above factors, enables the three-layer core-shell nanocomposites to possess good bactericidal and reinforcing effects, and has promising application prospects in the construction field. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0024] As attached Figure 1As shown, a method for preparing an in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete is characterized by the following steps:

[0025] Step 1: Mix sodium iron ethylenediaminetetraacetate (NaFeEDTA) and calcium nitrate in a certain proportion, add a certain concentration of ammonia solution and stir to dissolve, add hydrogen peroxide dropwise and stir for a period of time to obtain a solution of sodium iron ethylenediaminetetraacetate precursor material coated with calcium peroxide.

[0026] Step 2: Slowly add a certain amount of tetraethyl orthosilicate solution to the precursor material solution obtained in Step 1, stir, and stop hydrolyzing at room temperature for a period of time. After freeze drying and grinding, a three-layer core-shell structure composite material of sodium iron ethylenediaminetetraacetate / calcium peroxide / silica is obtained.

[0027] Step 3: The three-layer core-shell composite material obtained in Step 2 is calcined in nitrogen at a certain temperature to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica.

[0028] Step 4: Disperse the composite material obtained in Step 3 in ethanol, add a certain amount of aminosilane, stir for a period of time, filter and dry to obtain a three-layer core-shell structure composite material of single-atom iron nanozyme / porous calcium peroxide / porous silica with aminosilane grafted on the surface.

[0029] This method first utilizes sodium iron ethylenediaminetetraacetate (EDTA) as a core precursor, and through an in-situ reaction, calcium peroxide is coated onto its surface to form a composite precursor of calcium peroxide-coated EDTA. Further, a thin layer of silica is formed on the surface of the composite precursor by the directional hydrolysis of tetraethyl orthosilicate. Subsequently, through inert gas calcination, the EDTA decomposes in situ to form single-atom nanozymes, simultaneously releasing a gaseous pore-forming agent, resulting in porous calcium peroxide and silica, thus obtaining a three-layer core-shell composite material of single-atom iron nanozymes / porous calcium peroxide / porous silica. Finally, aminosilane grafting is used to obtain a three-layer core-shell composite material of single-atom iron nanozymes / porous calcium peroxide / porous silica with surface-grafted aminosilane.

[0030] Example 1

[0031] 1) Mix 1.0g of sodium iron ethylenediaminetetraacetate (NaFeEDTA) and 0.5g of calcium nitrate, add 0.01mol / L ammonia solution and stir to dissolve, add 0.5mol / L hydrogen peroxide dropwise, stir for 1h, and filter to obtain a solution of sodium iron ethylenediaminetetraacetate precursor material coated with calcium peroxide;

[0032] 2) Slowly add tetraethyl orthosilicate solution to the precursor material solution obtained in step 1), with the ratio of precursor material to tetraethyl orthosilicate solid being 1:0.1 and stir. After hydrolysis for 12 hours at room temperature, stop the process. After freeze-drying and grinding, obtain a three-layer core-shell structure composite material of sodium iron ethylenediaminetetraacetate / calcium peroxide / silica.

[0033] 3) The three-layer core-shell composite material from step 2) was calcined under nitrogen at 300°C for 1 hour to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica.

[0034] 4) Disperse the composite material obtained in step 3) in ethanol, add 3-aminopropyltrimethoxysilane, the mass ratio of 3-aminopropyltrimethoxysilane to the composite material is 0.01:1, stir for 12 h, filter and dry to obtain the sample of the three-layer core-shell structure composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica with surface grafted aminosilane in this embodiment.

[0035] Example 2

[0036] 1) Mix 1.0g of sodium iron ethylenediaminetetraacetate (NaFeEDTA) and 0.4g of calcium nitrate, add 0.1mol / L ammonia solution and stir to dissolve, add 0.01mol / L hydrogen peroxide dropwise, stir for 2h, and filter to obtain a solution of sodium iron ethylenediaminetetraacetate precursor material coated with calcium peroxide;

[0037] 2) Slowly add tetraethyl orthosilicate solution to the precursor material solution obtained in step 1), with the ratio of precursor material to tetraethyl orthosilicate solid being 1:0.2. Stir and hydrolyze for 24 hours at room temperature. After freeze-drying and grinding, a three-layer core-shell structure composite material of sodium iron ethylenediaminetetraacetate / calcium peroxide / silica is obtained.

[0038] 3) The three-layer core-shell composite material from step 2) was calcined under nitrogen at 310°C for 2 hours to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica.

[0039] 4) Disperse the composite material obtained in step 3) in ethanol, add a certain amount of 3-aminopropyltrimethoxysilane, the mass ratio of 3-aminopropyltrimethoxysilane to the composite material is 0.01:1, stir for 12 h, filter and dry to obtain the sample of the three-layer core-shell structure composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica with surface grafted aminosilane in this embodiment.

[0040] Example 3

[0041] 1) Mix 1.0g of sodium iron ethylenediaminetetraacetate (NaFeEDTA) and 0.3g of calcium nitrate in a certain proportion, add 0.08mol / L ammonia solution and stir to dissolve, add 0.05mol / L hydrogen peroxide dropwise, stir for 4h, and filter to obtain a solution of sodium iron ethylenediaminetetraacetate precursor material coated with calcium peroxide.

[0042] 2) Slowly add tetraethyl orthosilicate solution to the precursor material solution obtained in step 1), with the ratio of precursor material to tetraethyl orthosilicate solid being 1:0.3. Stir and hydrolyze for 16 hours at room temperature, then stop. After freeze-drying and grinding, a three-layer core-shell structure composite material of sodium iron ethylenediaminetetraacetate / calcium peroxide / silica is obtained.

[0043] 3) The three-layer core-shell composite material from step 2) was calcined under nitrogen at 320°C for 3 hours to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica.

[0044] 4) Disperse the composite material obtained in step 3) in ethanol, add a certain amount of 3-aminopropyltrimethoxysilane, the mass ratio of 3-aminopropyltrimethoxysilane to the composite material is 0.03:1, stir for 18 h, filter and dry to obtain the sample of the three-layer core-shell structure composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica with surface grafted aminosilane in this embodiment.

[0045] Example 4

[0046] 1) Mix 1.0g of sodium iron ethylenediaminetetraacetate (NaFeEDTA) and 0.1g of calcium nitrate in a certain proportion, add 0.5mol / L ammonia solution and stir to dissolve, add 0.2mol / L hydrogen peroxide dropwise, stir for 5h, and filter to obtain a solution of sodium iron ethylenediaminetetraacetate precursor material coated with calcium peroxide;

[0047] 2) Slowly add tetraethyl orthosilicate solution to the precursor material solution obtained in step 1), with the ratio of precursor material to tetraethyl orthosilicate solid being 1:0.4. Stir and hydrolyze for 24 hours at room temperature, then stop. After freeze-drying and grinding, a three-layer core-shell structure composite material of sodium iron ethylenediaminetetraacetate / calcium peroxide / silica is obtained.

[0048] 3) The three-layer core-shell composite material from step 2) was calcined under nitrogen at 350°C for 4 hours to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica.

[0049] 4) Disperse the composite material obtained in step 3) in ethanol, add 3-aminopropyltrimethoxysilane, the mass ratio of 3-aminopropyltrimethoxysilane to the composite material is 0.03:1, stir for 24 h, filter and dry to obtain the sample of the three-layer core-shell structure composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica with surface grafted aminosilane in this embodiment.

[0050] Example 5

[0051] 1) Mix 1.0g of sodium iron ethylenediaminetetraacetate (NaFeEDTA) and 0.3g of calcium nitrate in a certain proportion, add 0.2mol / L ammonia solution and stir to dissolve, add 0.5mol / L hydrogen peroxide dropwise, stir for 6h, and filter to obtain a solution of sodium iron ethylenediaminetetraacetate precursor material coated with calcium peroxide;

[0052] 2) Slowly add tetraethyl orthosilicate solution to the precursor material solution obtained in step 1), with the ratio of precursor material to tetraethyl orthosilicate solid being 1:0.5. Stir and hydrolyze for 18 hours at room temperature. After freeze-drying and grinding, a three-layer core-shell structure composite material of sodium iron ethylenediaminetetraacetate / calcium peroxide / silica is obtained.

[0053] 3) The three-layer core-shell composite material from step 2) was calcined under nitrogen at 330°C for 2 hours to obtain a three-layer core-shell composite material of single-atom iron nanozyme / porous calcium peroxide / porous silica.

[0054] 4) Disperse the composite material obtained in step 3) in ethanol, add 3-aminopropyltrimethoxysilane, the mass ratio of 3-aminopropyltrimethoxysilane to the composite material is 0.05:1, stir for 18 h, filter and dry to obtain the sample of the three-layer core-shell structure composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica with surface grafted aminosilane in this embodiment.

[0055] Performance testing

[0056] 1. Antibacterial performance test

[0057] According to the requirements of JC / T 2552-2019 "Fungicides for Concrete Admixtures", we tested the anti-mold and bactericidal properties of the samples obtained in Examples 1 to 5 and the blank sample. The test procedure is as follows: First, distilled water was added to the admixture to dilute its solid content to a concentration of 15%. Then, the same amount of microorganisms was injected into each group of samples and thoroughly stirred. The samples were placed in an incubator at 30±2℃ for incubation. During the incubation process, we observed whether mold, mycelium, or odor appeared.

[0058] Table 1 Antibacterial properties of different samples

[0059]

[0060] Note: The blank sample is without the addition of nanocomposite materials, and all other conditions are the same.

[0061] The results showed that all the control samples developed mold, mycelium, and odor within 3 months, while the same was not observed in Example 3 until 12 months later. The other examples did not show any signs of mold growth within 12 months. This indicates that this composite nanomaterial based on calcium peroxide and single-atom iron nanozymes has excellent antibacterial effects.

[0062] 2. Concrete setting time and compressive strength test

[0063] When conducting setting time tests, temperature and relative humidity were strictly controlled, following the conditions specified in GB / T50080~2002: a moisture curing chamber with a temperature of (20±1)℃ and a relative humidity of not less than 90%. Concrete strength tests were conducted according to the methods specified in GB 8076-2008 "Concrete Admixtures" and GB / T 50081-2002 "Test Methods for Mechanical Properties of Ordinary Concrete".

[0064] Table 2: Concrete setting time (20±1)℃ and strength test results for different samples

[0065]

[0066] Note: The admixture content refers to the mass fraction of the cementitious material. The blank sample is the one without the nanocomposite material. All other conditions are the same.

[0067] The data above shows that the setting time of concrete with different nanocomposite materials added was shorter than that of the blank sample. Specifically, the initial setting time of the nanomaterial prepared in Example 1 was extended by 3 hours and 20 minutes, and the final setting time was extended by 3 hours and 36 minutes compared to the blank sample, indicating that the addition of nanocomposite materials significantly shortened the setting time of concrete. Furthermore, the compressive strength data at different ages revealed that the 1-day strength of the specimens with added composite nanomaterials was higher than that of the blank sample, with a significant improvement effect. The 1-day strength of Example 5 was increased by 83.8% compared to the blank sample. The 28-day compressive strength was also higher after addition than the blank sample, indicating that the addition of the composite nanomaterial synthesized by this patent also improved the later-stage strength of the concrete.

[0068] The application of single-atom nanozymes in the field of concrete is relatively limited. While improving the density of concrete, single-atom nanozymes can also catalyze oxidation and reduction reactions in concrete, promote the transformation of harmful substances and oxides, thereby reducing the oxidation and corrosion process of concrete and improving its durability and corrosion resistance.

[0069] Although the present invention has been disclosed above with reference to preferred embodiments, these are not intended to limit the invention. Any person skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be defined by the scope of the claims of this application.

Claims

1. A method for preparing in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete, characterized in that: Includes the following steps: Step 1: Mix sodium iron ethylenediaminetetraacetate (NaFeEDTA) and calcium nitrate in a certain proportion, add a certain concentration of ammonia solution and stir to dissolve, add hydrogen peroxide dropwise and stir for a period of time to obtain a solution of sodium iron ethylenediaminetetraacetate precursor material coated with calcium peroxide. Step 2: Slowly add a certain amount of tetraethyl orthosilicate solution to the precursor material solution obtained in Step 1, stir, and stop hydrolyzing at room temperature for a period of time. After freeze drying and grinding, a three-layer core-shell structure composite material of sodium iron ethylenediaminetetraacetate / calcium peroxide / silica is obtained. Step 3: The three-layer core-shell composite material obtained in Step 2 is calcined in nitrogen at a certain temperature to obtain a three-layer core-shell composite material of single-atom iron nanoenzyme / porous calcium peroxide / porous silica. Step 4: Disperse the composite material obtained in Step 3 in ethanol, add a certain amount of aminosilane, stir for a period of time, filter and dry to obtain a three-layer core-shell structure composite material of single-atom iron nanozyme / porous calcium peroxide / porous silica with aminosilane grafted on the surface.

2. The method for preparing the in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete according to claim 1, characterized in that: In step one, the mass ratio of sodium iron ethylenediaminetetraacetate (NaFeEDTA) to calcium nitrate is 1:(0.5~0.1).

3. The method for preparing the in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete according to claim 2, characterized in that: In step one, the concentration of ammonia is 0.01~0.5 mol / L; the concentration of hydrogen peroxide is 0.01~0.5 mol / L; and the stirring time is 1~6 h.

4. The method for preparing the in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete according to claim 3, characterized in that: In step two, the mass ratio of the calcium peroxide-coated sodium iron ethylenediaminetetraacetate precursor material to solid tetraethyl orthosilicate is 1:(0.5~0.1), and the hydrolysis time is 12~24 h.

5. The method for preparing the in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete according to claim 4, characterized in that: In step three, the calcination temperature is 300~350℃ and the calcination time is 1~4 h.

6. The method for preparing the in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete according to claim 5, characterized in that: In step four, the aminosilane is 3-aminopropyltrimethoxysilane.

7. The method for preparing the in-situ reinforced single-atom nanoenzyme bactericidal composite material for concrete according to claim 6, characterized in that: In step four, the mass ratio of aminosilane to the composite material obtained in step three dispersed in ethanol is (0.01~0.05):1, and the stirring time is 12~24 h.

Images