Photocatalytic carbonized plate and preparation process thereof

Abstract

The application discloses a kind of photocatalytic carbonized board and preparation process thereof.The preparation process includes the following steps: carbonized cementing material, titanium source, anhydrous ethanol, water A, glacial acetic acid are uniformly mixed to obtain precursor solution; precursor solution is subjected to hydrothermal reaction, after reaction, filtration and drying, to obtain mixture; the mixture and water B are uniformly mixed, then pressed into a thin plate, and finally carbonized curing to obtain photocatalytic carbonized board.The application coats titanium dioxide on the surface of carbonized cementing material by hydrothermal method, and uses the carbon fixation and condensation function of carbonized cementing material to make photocatalytic board, which avoids uneven distribution of photocatalytic powder in the board, and is beneficial to improve the efficiency of photocatalytic degradation of pollutants and mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of carbon solidification and photocatalytic materials technology, and in particular to a photocatalytic carbonization plate and its preparation process. Background Technology

[0002] There are many types of boards on the market, but most of them have only one function. Innovation in board function is crucial. Photocatalytic boards can use sunlight or lamplight to decompose organic pollutants in the environment, making them a green functional material.

[0003] Currently, research on photocatalytic boards is limited. Chinese patent CN108393983A discloses a method for preparing a photocatalytic formaldehyde-removing board. This patent uses pressure impregnation to allow the photocatalyst to penetrate into the pores of wood. The resulting board can reduce volatile organic compound (VOC) pollution in the indoor environment and has advantages such as good photocatalytic activity, high formaldehyde degradation rate, and good dimensional stability. However, because the photocatalyst is combined with the wood through penetration, its durability is relatively poor. Chinese patent CN107056213B discloses a gypsum board with temperature and humidity regulating photocatalytic properties and its preparation method. This patent obtains a gypsum board with temperature and humidity regulating photocatalytic properties by uniformly mixing a heat-humidity-light composite filler, building gypsum powder, water, and a setting time regulator, followed by solidification. However, this method only physically mixes the heat-humidity-light composite filler and building gypsum powder, which is not conducive to sufficient contact between the heat-humidity-light composite filler and other materials. This easily causes the materials to agglomerate, forming isolated powder particles, resulting in low photocatalytic degradation efficiency.

[0004] Therefore, there is an urgent need to provide a new preparation process for photocatalytic plates to avoid the problem of uneven distribution of photocatalytic powder within the plate affecting the photocatalytic degradation efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a photocatalytic carbonization plate and its preparation process, thereby solving the technical problem that the uneven distribution of photocatalytic powder in the plate affects the photocatalytic degradation efficiency in the prior art.

[0006] In a first aspect, the present invention provides a process for preparing a photocatalytic carbonization plate, comprising the following steps:

[0007] The carbonized cementitious material, titanium source, anhydrous ethanol, water A, and glacial acetic acid were mixed evenly to obtain a precursor solution.

[0008] The precursor solution was subjected to a hydrothermal reaction. After the reaction was completed, the mixture was filtered and dried to obtain a mixture.

[0009] Mix the mixture with water B until homogeneous, then press it into a thin sheet, and finally cure it by carbonization to obtain a photocatalytic carbonized board.

[0010] Secondly, the present invention provides a photocatalytic carbonization plate, which is obtained by the preparation process of the photocatalytic carbonization plate provided in the first aspect of the present invention.

[0011] Compared with the prior art, the beneficial effects of the present invention include:

[0012] This invention uses a hydrothermal method to coat titanium dioxide onto the surface of a carbonized cementitious material, and utilizes the carbon-fixing and coagulation function of the carbonized cementitious material to produce a photocatalytic plate. This avoids uneven distribution of photocatalytic powder within the plate, which is beneficial to improving the efficiency and mechanical properties of photocatalytic degradation of pollutants. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of carbon fixation of the photocatalytic carbonization plate of the present invention during carbon dioxide curing. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0015] In a first aspect, the present invention provides a process for preparing a photocatalytic carbonization plate, comprising the following steps:

[0016] S1. Mix the carbonized cementitious material, titanium source, anhydrous ethanol, water A, and glacial acetic acid evenly to obtain a precursor solution;

[0017] S2. The precursor solution is subjected to a hydrothermal reaction. After the reaction is complete, the mixture is filtered and dried to obtain a mixture.

[0018] S3. Mix the mixture and water B evenly, then press it into a thin plate, and finally obtain the photocatalytic carbonized plate through carbonization curing.

[0019] This invention first disperses the carbonized cementitious material in a titanium dioxide precursor solution, ensuring thorough mixing. Then, a hydrothermal method is used to more uniformly coat the carbonized cementitious material with the titanium dioxide formed during the hydrothermal reaction, reducing titanium dioxide agglomeration and promoting photocatalytic activity. Furthermore, the hydrothermal method is a single-pot process, simple to operate and easy to industrialize. This invention utilizes the carbon-fixing and coagulation function of the carbonized cementitious material to produce boards, which not only consumes carbon dioxide, contributing to carbon peaking targets, but also achieves photocatalytic degradation of pollutants. In addition, when the carbonized cementitious material is industrial waste, it also realizes the resource utilization of solid waste.

[0020] In this invention, it should be noted that after the hydrothermal reaction is completed, a drying operation is required to remove volatile organic compounds such as ethanol from the system to avoid adverse effects on subsequent processes. At the same time, since the carbonized cementitious material only reacts with carbon dioxide in the presence of water, water B needs to be added after drying to ensure that it is mixed evenly with the mixture.

[0021] In this embodiment, the carbonized cementitious material is at least one of the following: calcium silicate minerals with low hydration activity and high carbonization activity, or industrial waste containing at least 60 wt% calcium silicate minerals with low hydration activity and high carbonization activity.

[0022] Among them, the calcium silicate mineral with low hydration activity and high carbonization activity is at least one of γ-type dicalcium silicate, monocalcium silicate, and tricalcium disilicate; the industrial waste residue can be materials with low hydration activity and high carbonization activity, such as steel slag and magnesium slag, and this invention does not limit this.

[0023] In this embodiment, the titanium source is tetrabutyl titanate.

[0024] In this embodiment, the ratio of carbonized cementitious material to titanium source is (5-10) g: 1 ml, preferably (6-8) g: 1 ml, and more preferably 7 g: 1 ml. Within this ratio range, it is beneficial to improve the uniformity of the hydrothermal reaction. At the same time, if the proportion of steel slag is too high, the photocatalytic efficiency will decrease; if the proportion of steel slag is too low, it will be impossible to form a plate through carbonization.

[0025] In this embodiment, the volume ratio of titanium source, anhydrous ethanol, water A, and glacial acetic acid is 1:(4-5):(2-3):(2-3), and more specifically 1:5:2:2.

[0026] In this embodiment, the carbonized cementitious material, titanium source, anhydrous ethanol, water A, and glacial acetic acid are mixed evenly by stirring. Furthermore, the stirring time is 20-60 minutes, and the stirring speed is 800-1000 rpm.

[0027] In this embodiment, the hydrothermal reaction temperature is 160-180℃, and the hydrothermal reaction time is 3-9 hours. Under these hydrothermal conditions, the formed titanium dioxide crystal is anatase, and the TiO2 lattice contains many defects and vacancies, thereby generating more oxygen vacancies to capture electrons, thus exhibiting high photocatalytic activity.

[0028] In this embodiment, the drying temperature is 80-110℃ and the drying time is 12-24h.

[0029] In this embodiment, water B accounts for 10%-18% of the mixture mass. Within this range, an optimal humidity environment can be provided for the carbonization process of the board.

[0030] In this embodiment, the forming pressure is 20-60 MPa during the pressing process into a thin sheet.

[0031] In this embodiment, during the carbonization curing process, the concentration of carbon dioxide is 60%-90%, the carbonization time is 6-12 hours, and the carbonization pressure is 0-0.5 MPa. Under these carbonization curing conditions, the obtained carbonized board has the highest strength.

[0032] Taking steel slag as the carbonized cementitious material and tetrabutyl titanate as the titanium source as an example, the mechanism involved in this invention will be explained as follows:

[0033] Glacial acetic acid acts as a chelating agent, reacting with tetrabutyl titanate to inhibit its hydrolysis. Ethanol can dissolve tetrabutyl titanate and hinder the formation of hydrogen chains through steric hindrance, thus slowing down the hydrolysis reaction and preventing the rapid hydrolysis of tetrabutyl titanate from affecting the formation of titanium dioxide and reducing its photocatalytic activity.

[0034] Ti(OC4H9)4+2H2O→TiO2+4C4H9OH

[0035] When carbon dioxide is introduced into the photocatalytic plate, the carbon dioxide reacts with water to produce carbonic acid. The carbonic acid ionizes into hydrogen ions and bicarbonate ions, and the bicarbonate ions ionize into hydrogen ions and carbonate ions. The calcium and magnesium ions rich in steel slag are released and combine with carbonate ions to form carbonates, thereby improving the strength of the product.

[0036] CO2 + H2O → H2CO3 → H + +HCO3 - →2H + +CO3 2-

[0037] Ca 2+ +CO3 2- →CaCO3

[0038] Mg 2+ +CO3 2- →MgCO3

[0039] Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

[0040] xCaO·ySiO2·zH2O+xCO2→xCaCO3+y(SiO2)·t H2O+(zt)H2O

[0041] Fe + CO₂ + H₂O → FeCO₃ + H₂

[0042] Secondly, the present invention provides a photocatalytic carbonization plate, which is obtained by the preparation process of the photocatalytic carbonization plate provided in the first aspect of the present invention.

[0043] Example 1

[0044] (1) Mix 100g of steel slag, 10ml of tetrabutyl titanate, 50ml of anhydrous ethanol, 20ml of water and 20ml of glacial acetic acid evenly to obtain a precursor solution.

[0045] (2) The precursor solution was placed in a hydrothermal reactor and then hydrothermally reacted at 180°C for 3 hours. After the reaction was completed, the product was filtered and dried at 110°C for 12 hours to obtain a mixture.

[0046] (3) Add 20g of water to the mixture and mix evenly. Then press it into shape under a pressure of 20MPa. Finally, carbonize it in a 90% carbon dioxide environment for 12h with a carbonization pressure of 0.04MPa to obtain the photocatalytic plate.

[0047] Example 2

[0048] (1) Mix 70g of steel slag, 10ml of tetrabutyl titanate, 50ml of anhydrous ethanol, 20ml of water and 20ml of glacial acetic acid evenly to obtain a precursor solution.

[0049] (2) The precursor solution was placed in a hydrothermal reactor and then hydrothermally reacted at 180°C for 3 hours. After the reaction was completed, the product was filtered and dried at 110°C for 12 hours to obtain a mixture.

[0050] (3) Add 16g of water to the mixture and mix evenly. Then press it into shape under a pressure of 20MPa. Finally, carbonize it in a 90% carbon dioxide environment for 12h with a carbonization pressure of 0.04MPa to obtain the photocatalytic plate.

[0051] Example 3

[0052] (1) Mix 50g of steel slag, 10ml of tetrabutyl titanate, 50ml of anhydrous ethanol, 20ml of water and 20ml of glacial acetic acid evenly to obtain a precursor solution.

[0053] (2) The precursor solution was placed in a hydrothermal reactor and then hydrothermally reacted at 180°C for 3 hours. After the reaction was completed, the product was filtered and dried at 110°C for 12 hours to obtain a mixture.

[0054] (3) Add 15g of water to the mixture and mix evenly. Then press it into shape under a pressure of 20MPa. Finally, carbonize it in a 90% carbon dioxide environment for 12h with a carbonization pressure of 0.04MPa to obtain the photocatalytic plate.

[0055] Comparative Example 1

[0056] (1) Mix 10 ml of tetrabutyl titanate, 50 ml of anhydrous ethanol, 20 ml of water and 20 ml of glacial acetic acid evenly to obtain a precursor solution;

[0057] (2) The precursor solution was placed in a hydrothermal reactor and then hydrothermally reacted at 180°C for 3 hours. After the reaction was completed, the product was filtered and dried at 110°C for 12 hours to obtain a mixture.

[0058] (3) Add 50g of steel slag and 15g of water to the mixture and mix evenly. Then press it into shape under a pressure of 20MPa. Finally, carbonize it in a 90% carbon dioxide environment for 12h with a carbonization pressure of 0.04MPa to obtain the photocatalytic plate.

[0059] Performance testing

[0060] Photocatalytic performance test: First, prepare a 20 mg / L methyl orange solution. Take 200 ml of methyl orange solution and put it into a 500 ml container. Add the photocatalytic plates (plate size is 4 cm * 4 cm * 1 cm) from Examples 1-3 and Comparative Example 1. Then, place them under a UV lamp to carry out a degradation comparison experiment with the same mass and the same time. Use a UV spectrophotometer to detect and calculate the degradation efficiency.

[0061] Plate strength testing: The strength was determined using a Jinan microcomputer-controlled electronic universal testing machine.

[0062] Table 1

[0063] Degradation efficiency (%) Sheet strength (MPa) Example 1 48％ 8.7 Example 2 57％ 7.0 Example 3 59％ 4.5 Comparative Example 1 50％ 5.0

[0064] As shown in Table 1, as the proportion of steel slag decreases, the degradation efficiency of the slab increases, but the slab strength decreases. When the ratio of steel slag to tetrabutyl titanate is 7g:1ml, further reducing the amount of steel slag does not significantly improve the degradation efficiency, but leads to a significant decrease in slab strength. Examples 3 and 1 (Comparative Example 1) demonstrate that introducing steel slag into the hydrothermal system, while causing a slight decrease in slab strength, significantly improves the degradation efficiency.

[0065] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A process for preparing a photocatalytic carbonization plate, characterized in that, Includes the following steps: The carbonized cementitious material, titanium source, anhydrous ethanol, water A, and glacial acetic acid were mixed evenly to obtain a precursor solution. The precursor solution was subjected to a hydrothermal reaction. After the reaction was completed, the mixture was filtered and dried to obtain a mixture. The mixture is thoroughly mixed with water B, then pressed into a thin sheet, and finally cured by carbonization to obtain a photocatalytic carbonized board; wherein, The ratio of the carbonized cementitious material to the titanium source is (5-10) g: 1 ml; The carbonized cementitious material is at least one of the following: calcium silicate minerals with low hydration activity and high carbonization activity, or industrial waste containing at least 60 wt% calcium silicate minerals with low hydration activity and high carbonization activity. The titanium source is tetrabutyl titanate; The volume ratio of the titanium source, anhydrous ethanol, water A, and glacial acetic acid is 1:(4-5):(2-3):(2-3).

2. The preparation process of the photocatalytic carbonization plate according to claim 1, characterized in that, The calcium silicate mineral with low hydration activity and high carbonization activity is at least one of γ-type dicalcium silicate, monocalcium silicate, and tricalcium disilicate.

3. The preparation process of the photocatalytic carbonization plate according to claim 1, characterized in that, The industrial waste residue is steel slag or magnesium slag.

4. The preparation process of the photocatalytic carbonization plate according to claim 1, characterized in that, The hydrothermal reaction temperature is 160-180℃, and the hydrothermal reaction time is 3-9 hours.

5. The preparation process of the photocatalytic carbonization plate according to claim 1, characterized in that, The water B comprises 10%-18% of the mass of the mixture.

6. The preparation process of the photocatalytic carbonization plate according to claim 1, characterized in that, During the pressing process into thin plates, the forming pressure is 20-60 MPa; during the carbonization curing process, the carbon dioxide concentration is 60%-90%, the carbonization time is 6-12 hours, and the carbonization pressure is 0-0.5 MPa.

7. A photocatalytic carbonization plate, characterized in that, The photocatalytic carbonization plate is obtained by the preparation method of the photocatalytic carbonization plate according to any one of claims 1-6.

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