A single-atom Co-anchored TiO2 catalyst, its preparation method and application

Abstract

The application belongs to the technical field of organic pollutant treatment, and particularly relates to a single-atom Co-anchored TiO2 catalyst and a preparation method and application thereof. The application provides a single-atom Co-anchored TiO2 catalyst, which comprises nano TiO2 and single-atom Co; the single-atom Co is dispersed on the surface of the nano TiO2; the loading amount of the single-atom Co is 0.1-1 wt%, the nano TiO2 is in the shape of a doughnut, and the specific surface area of the nano TiO2 is 100-150 m 2 / g. The single-atom Co-anchored TiO2 catalyst provided by the application can degrade dibutyl phthalate DBP in water by 100%, has a high single-atom loading amount, has higher visible light activity, and can significantly improve the removal rate of persistent organic pollutants such as plasticizers. The single-atom Co-anchored TiO2 catalyst provided by the application can catalytically degrade organic pollutants in water bodies with a pH value of 3-12, has excellent reusability, and greatly reduces the economic cost of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of organic pollutant treatment technology, and specifically relates to a single-atom Co-anchored TiO2 catalyst, its preparation method, and its application. Background Technology

[0002] Dibutyl phthalate (DBP) is a commonly used plasticizer in industrial production. It is inexpensive, easy to process, and produced and used in large quantities. However, it is easily released into the environment during processing and use, exhibiting characteristics such as light color, low odor, low-temperature resistance, and difficulty in natural degradation. Due to the excellent stability of phthalic plasticizers, their hydrolysis half-life is very long, with almost no volatilization loss. However, organisms can accumulate phthalic plasticizers. Studies have shown significant residues of these compounds in aquatic organisms. Phthalic plasticizers can cause adverse effects on organisms, including tissue carcinogenesis, developmental malformations, reproductive toxicity, and gene mutations. Due to the widespread use of phthalic plasticizers, DBP is now frequently detected in water, soil, food, and the atmosphere.

[0003] With the increasing sophistication of national environmental protection standards and the growing public awareness of environmental safety, technologies for treating organic pollutants in water bodies are receiving increasing attention. Studies have shown that photocatalysis and persulfate have a positive synergistic effect on the removal of organic pollutants; compared with single treatment methods, synergistic treatment is more effective and efficient. Several existing publications report the use of noble metals (Au, Pt, Ag, and Pd), transition metals (Cr, Mn, Fe, Co, Ni, Cu, and Zn), or lanthanides (La, Nd, Sm, Eu, Gd, Yb, or Pr) as doping metals to improve the photocatalytic activity of TiO2. However, due to the tendency of single atoms to aggregate and the limited surface area of ​​the support, the adhesion of single atoms on the support surface is unstable, leading to easy detachment and low single-atom loading, often not exceeding 0.3 wt%. The easy aggregation of surface-loaded single atoms makes the catalyst system unstable, resulting in low catalytic activity and low efficiency in the catalytic degradation of organic pollutants, failing to meet requirements. How to achieve high dispersion, stable adhesion, and high loading of single atoms on the support surface is a key challenge in preparation. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a single-atom Co-anchored TiO2 catalyst, its preparation method, and its application. The catalyst provided by this invention has a high Co loading on its surface and can degrade the plasticizer dibutyl phthalate (DBP) 100%.

[0005] This invention provides a TiO2 catalyst anchored to a single atom of Co, comprising nano-TiO2 and a single atom of Co;

[0006] The single-atom Co is dispersed on the surface of the nano-TiO2;

[0007] The loading of the single-atom Co is 0.1-1 wt%, and the remainder is nano-TiO2;

[0008] The nano-TiO2 is donut-shaped, with an outer diameter of 500–700 nm, an inner diameter of 50–300 nm, and a thickness of 300–400 nm along the normal direction of the nano-TiO2; the specific surface area of ​​the nano-TiO2 is 100–150 m² / g. 2 / g.

[0009] This invention also provides a method for preparing the single-atom Co-anchored TiO2 catalyst described in the above technical solution, comprising the following preparation steps:

[0010] Dicarboxylic acid and organotitanium were mixed and subjected to a thermal reaction to obtain the MIL-125 precursor.

[0011] The MIL-125 precursor was mixed with tannic acid and subjected to a hydrothermal etching reaction to obtain an intermediate product.

[0012] The intermediate product was mixed with a cobalt-based compound and then calcined to obtain the single-atom Co-anchored TiO2 catalyst.

[0013] Preferably, the dicarboxylic acid includes terephthalic acid or 2-aminoterephthalic acid;

[0014] The organic titanium is tetrabutyl titanate or tetraisopropyl titanate;

[0015] The cobalt-based compound is cobalt nitrate, cobalt chloride, or cobalt acetate.

[0016] Preferably, the mass ratio of the dicarboxylic acid to the organotitanium is 2-5:1-3;

[0017] The thermal reaction is carried out at a temperature of 120–180°C for 12–24 hours.

[0018] Preferably, the mass ratio of the MIL-125 precursor to tannic acid is 1:0.5 to 3;

[0019] The hydrothermal etching reaction is carried out at a temperature of 100–200°C for 1–4 hours.

[0020] Preferably, the mass ratio of the intermediate product to the cobalt-based compound is 500–1000:5–50;

[0021] The calcination temperature is 400–800℃, and the calcination time is 2–4 hours.

[0022] This invention also provides the application of the single-atom Co-anchored TiO2 catalyst described in the above technical solution or the single-atom Co-anchored TiO2 catalyst prepared by the above preparation method in the removal of organic pollutants in water.

[0023] Preferably, the organic pollutant includes a plasticizer.

[0024] Preferably, the application of the single-atom Co-anchored TiO2 catalyst for removing organic pollutants from water includes the following steps:

[0025] TiO2 catalyst anchored to single-atom Co, persulfate, and wastewater to be treated were mixed and subjected to phototreatment under visible light.

[0026] Preferably, the persulfate includes one or more of potassium persulfate, potassium persulfate, potassium persulfate, sodium persulfate, and sodium persulfate.

[0027] The amount of the single-atom Co-anchored TiO2 catalyst used is 0.2–2 g / L;

[0028] The amount of persulfate used is 0.3–3 g / L;

[0029] The pH value of the wastewater to be treated is 3 to 12.

[0030] This invention provides a single-atom Co-anchored TiO2 catalyst, comprising nano-TiO2 and single-atom Co; the single-atom Co is dispersed on the surface of the nano-TiO2; the loading of the single-atom Co is 0.1–1 wt%, with the remainder being nano-TiO2; the nano-TiO2 is donut-shaped, with an outer diameter of 500–700 nm, an inner diameter of 50–300 nm, and a thickness of 300–400 nm along the normal direction of the nano-TiO2; the specific surface area of ​​the nano-TiO2 is 100–150 m² / g. 2 / g.

[0031] The single-atom Co-anchored TiO2 catalyst provided by this invention has a high single-atom loading. The Co single atom enhances the responsiveness of TiO2 to visible light and also serves as an activation site for persulfate. Compared to commercially available P... 25 Nano-sized titanium dioxide catalysts possess more active sites and a larger specific surface area. The catalyst provided by this invention exhibits higher visible light activity, significantly improving the removal rate of persistent organic pollutants such as plasticizers. The single-atom Co-anchored TiO2 catalyst provided by this invention can catalytically degrade organic pollutants in water with a pH value of 3–12, and shows good resistance to interference from anions in the water. Furthermore, the catalyst provided by this invention has excellent reusability, greatly reducing the economic cost of catalysts.

[0032] The results of the examples and application examples show that the single-atom Co-anchored TiO2 catalyst provided by the present invention has a Co loading of 0.1-1 wt%, a DBP degradation rate of 100%, and a specific surface area of ​​100-150 m². 2 / g; In the repeated DBP degradation test of Application Example 3 of this invention, the leaching concentration of Co in the TiO2 catalyst anchored by single atom Co was <0.2mg / L in the third reuse and <0.1mg / L in the fourth to eighth reuses. The leaching concentration of Co remained stable at a low level, indicating that the loss of Co was very small. Moreover, after 8 reuses, the degradation rate of DBP by the TiO2 catalyst anchored by single atom Co still reached 96.061%, which has a high catalytic degradation efficiency.

[0033] This invention also provides a method for preparing the single-atom Co-anchored TiO2 catalyst, comprising the following steps: mixing a dicarboxylic acid with an organotitanium compound and performing a thermal reaction to obtain a MIL-125 precursor; mixing the MIL-125 precursor with tannic acid and performing a hydrothermal etching reaction to obtain an intermediate product; and mixing the intermediate product with a cobalt-based compound and calcining it to obtain the single-atom Co-anchored TiO2 catalyst.

[0034] This invention involves a thermal reaction of dicarboxylic acid with organotitanium to prepare a MIL-125 precursor with an extremely large specific surface area, maximizing the attachment sites of Co single atoms on the TiO2 surface. The invention employs hydrothermal etching with tannic acid to oxidize and convert the MIL-125 precursor into erythrocyte-type TiO2, i.e., the intermediate product—erythrocyte-type TiO2. This makes the TiO2 structure more stable and prevents excessive collapse into fragments during subsequent calcination. This invention achieves high dispersion loading of Co single atoms on the TiO2 surface through Co-O coordination replacing Ti-O coordination, maximizing the exposure sites of Co single atoms and nanoparticles on TiO2. After calcination, the central region of the erythrocyte-type TiO2 collapses, ultimately forming a donut-like shape (e.g., ...). Figure 1 (As shown). The preparation method provided by this invention is mild and simple. The prepared TiO2 has a high specific surface area and can stably load a large number of Co single atoms. It still has excellent degradation effect on organic pollutants even after repeated recycling. The preparation method provided by this invention has simple steps, does not require the addition of multiple additives, is low in cost, and is easy to carry out industrial production, thus having considerable market application prospects.

[0035] This invention also provides the application of the single-atom Co-anchored TiO2 catalyst described in the above-mentioned technical solution in the removal of organic pollutants from water. The single-atom Co-anchored TiO2 catalyst provided by this invention, in conjunction with persulfate under visible light, can achieve 100% degradation of phthalic plasticizers in water. The single-atom Co-anchored TiO2 catalyst provided by this invention can catalytically degrade organic pollutants in water with a pH value of 3-12, and can be used in various scenarios such as natural water bodies, domestic sewage, or industrial wastewater. Even after being reused eight times, the catalyst provided by this invention still maintains a degradation efficiency of 96.061% for phthalic plasticizers, greatly reducing the cost of water treatment. Attached Figure Description

[0036] Figure 1 The flowchart shows the synthesis process of the single-atom Co-anchored TiO2 catalyst in Example 1.

[0037] Figure 2 SEM image of the MIL-125 precursor prepared in Example 1;

[0038] Figure 3 This is a TEM image of the single-atom Co-anchored TiO2 catalyst prepared in Example 1;

[0039] Figure 4 HAADF-STEM image of the single-atom Co-anchored TiO2 catalyst prepared in Example 1;

[0040] Figure 5 Line scan results of the single-atom Co-anchored TiO2 catalyst prepared in Example 1;

[0041] Figure 6 The internal strain diagram of the single-atom Co-anchored TiO2 catalyst prepared in Example 1 is shown.

[0042] Figure 7 The XRD pattern of the single-atom Co-anchored TiO2 catalyst prepared in Example 1;

[0043] Figure 8 The FT-IR spectrum of the single-atom Co-anchored TiO2 catalyst prepared in Example 1 is shown below.

[0044] Figure 9 XPS image of the single-atom Co-anchored TiO2 catalyst prepared in Example 1;

[0045] Figure 10 XANES diagram of the single-atom Co-anchored TiO2 catalyst prepared in Example 1;

[0046] Figure 11The EXAFS image of the single-atom Co-anchored TiO2 catalyst prepared in Example 1 is shown.

[0047] Figure 12 The EXAFS two-dimensional color patch image of the single-atom Co-anchored TiO2 catalyst prepared in Example 1;

[0048] Figure 13 Line graph showing the DBP degradation rate under different pH conditions in Application Example 2;

[0049] Figure 14 The bar chart shows the DBP degradation rate under the condition of repeated catalyst reuse in Application Example 3;

[0050] Figure 15 Line graphs showing the degradation rate of DBP under different anionic conditions for application of Comparative Example 3;

[0051] Figure 16 Line graphs showing the DBP degradation rates for Application Example 1 and Comparative Examples 1–5. Detailed Implementation

[0052] This invention provides a TiO2 catalyst anchored to a single atom of Co, comprising nano-TiO2 and a single atom of Co;

[0053] The single-atom Co is dispersed on the surface of the nano-TiO2;

[0054] The loading of the single-atom Co is 0.1-1 wt%, and the remainder is nano-TiO2;

[0055] The nano-TiO2 is donut-shaped, with an outer diameter of 500–700 nm, an inner diameter of 50–300 nm, and a thickness of 300–400 nm along the normal direction of the nano-TiO2; the specific surface area of ​​the nano-TiO2 is 100–150 m² / g. 2 / g.

[0056] Unless otherwise specified, all raw materials used in this invention are preferably commercially available products.

[0057] The single-atom Co-anchored TiO2 catalyst provided by this invention comprises 0.1–1 wt% single-atom Co, more preferably 0.3–0.6 wt%. In this invention, the single-atom Co is dispersed on the TiO2 surface. This invention utilizes single-atom Co to enhance the responsiveness of TiO2 to visible light and simultaneously serves as an activation site for persulfate, thereby providing the catalyst with more active sites and improving the catalyst's visible light activity and degradation efficiency for organic pollutants.

[0058] The single-atom Co-anchored TiO2 catalyst provided by this invention comprises the remainder nano-TiO2. In this invention, the nano-TiO2 is donut-shaped, with an outer diameter of 500–700 nm, preferably 500–600 nm, an inner diameter of 50–300 nm, preferably 50–200 nm, and a thickness of 300–400 nm along the normal direction of the nano-TiO2. In this invention, the specific surface area of ​​the nano-TiO2 is 100–150 m² / s. 2 / g.

[0059] The donut-shaped TiO2 provided by this invention is superior to commercially available P. 25 Nano-TiO2 has a larger specific surface area and can stably load more Co single atoms. The nano-TiO2 provided by this invention has higher visible light activity, which can significantly improve the removal rate of persistent organic pollutants such as plasticizers, and still has excellent degradation effect on organic pollutants after repeated recycling.

[0060] This invention also provides a method for preparing the single-atom Co-anchored TiO2 catalyst described in the above technical solution, comprising the following preparation steps:

[0061] Dicarboxylic acid and organotitanium were mixed and subjected to a thermal reaction to obtain the MIL-125 precursor.

[0062] The MIL-125 precursor was mixed with tannic acid and subjected to a hydrothermal etching reaction to obtain an intermediate product.

[0063] The intermediate product was mixed with a cobalt-based compound and then calcined to obtain the single-atom Co-anchored TiO2 catalyst.

[0064] This invention involves mixing dicarboxylic acid with organic titanium and subjecting them to a thermal reaction to obtain the MIL-125 precursor.

[0065] In this invention, the dicarboxylic acid preferably includes terephthalic acid or 2-aminoterephthalic acid, more preferably terephthalic acid. In this invention, the organotitanium is preferably tetrabutyl titanate or tetraisopropyl titanate, more preferably tetrabutyl titanate. In this invention, the mass ratio of the dicarboxylic acid to the organotitanium is preferably 2–5:1–3, more preferably 3–3.5:1.5–1.6.

[0066] In this invention, the dicarboxylic acid is preferably prepared as a dicarboxylic acid solution. In this invention, the solvent for the dicarboxylic acid solution is preferably N,N-dimethylformamide (DMF). In this invention, the preferred ratio of the dicarboxylic acid to DMF is 2-5 g: 40-100 mL. In this invention, the dicarboxylic acid and DMF are preferably mixed by stirring, and the stirring time is preferably ≥30 min.

[0067] In this invention, the organotitanium is preferably prepared as an organotitanium solution. In this invention, the solvent for the organotitanium solution is preferably a small-molecule organic alcohol, more preferably methanol, ethanol, or propylene glycol. In this invention, the volume ratio of the organotitanium to the small-molecule organic alcohol is preferably 1–3:5–20. In this invention, the organotitanium and the small-molecule organic alcohol are preferably mixed by stirring, and the stirring time is preferably ≥30 min.

[0068] In this invention, the thermal reaction is preferably carried out in a reaction vessel. The reaction temperature is preferably 120–180°C, more preferably 150–160°C. The reaction time is preferably 12–24 hours, more preferably 18–24 hours, and even more preferably 24 hours.

[0069] In a specific embodiment of the present invention, it is preferable to rapidly add the organic titanium solution to the dicarboxylic acid solution, stir for 10 minutes, and then transfer the resulting mixed solution to a reaction vessel for thermal reaction.

[0070] Following the thermal reaction, the present invention preferably further includes centrifuging the obtained liquid to collect a white product; washing, drying, and grinding the white product to obtain the MIL-125 precursor. In this invention, the washing is preferably performed by sequentially washing the obtained white product with DMF and methanol, with the DMF washing performed at least three times and the methanol washing performed at least three times. In this invention, the drying is preferably performed in an oven. In this invention, the drying temperature is preferably 60°C, and the drying time is preferably 12 hours. In this invention, the grinding mesh size is preferably ≥200 mesh.

[0071] After obtaining the MIL-125 precursor, the present invention mixes the MIL-125 precursor with tannic acid and performs a hydrothermal etching reaction to obtain an intermediate product.

[0072] In this invention, the mass ratio of the MIL-125 precursor to tannic acid is preferably 1:0.5-3, more preferably 1:1-1.2. In this invention, the MIL-125 precursor is preferably prepared as a MIL-125 precursor dispersion. In this invention, the ratio of MIL-125 precursor to water in the MIL-125 precursor dispersion is preferably 1g:40-100mL. In this invention, the water is preferably deionized water. In this invention, the mixing is preferably carried out under stirring conditions, and the stirring time is preferably 20-40 min. In this invention, after mixing, the mixture containing the MIL-125 precursor and tannic acid is preferably transferred to a reaction vessel for hydrothermal etching. In this invention, the reaction vessel is preferably a polytetrafluoroethylene (PTFE) reaction vessel.

[0073] In this invention, the reaction temperature of the hydrothermal etching reaction is preferably 100–200°C, more preferably 120–180°C. In this invention, the reaction time of the hydrothermal etching reaction is preferably 1–4 h, more preferably 2–2.5 h.

[0074] Following the hydrothermal etching, the present invention preferably further includes centrifuging the hydrothermal etching solution to collect the brown substance, and then washing and drying the brown substance. In this invention, the washing reagent is preferably deionized water, and the number of washing cycles is preferably ≥3. In this invention, the drying temperature is preferably 60°C, and the drying time is preferably 12 hours.

[0075] In this invention, the intermediate product is red blood cell type TiO2, which has a high specific surface area. It is subjected to etching and pre-oxidation to prevent collapse during subsequent calcination.

[0076] After obtaining the intermediate product, the present invention mixes the intermediate product with a cobalt-based compound and then calcines it to obtain the single-atom Co-anchored TiO2 catalyst.

[0077] In this invention, the cobalt-based compound is preferably cobalt nitrate, cobalt chloride, or cobalt acetate, and more preferably cobalt nitrate.

[0078] In this invention, the mass ratio of the intermediate product to the cobalt-based compound is preferably 500-1000:5-50, more preferably 500-1000:10-20.

[0079] In this invention, the intermediate product is preferably prepared as an intermediate product dispersion. In this invention, the ratio of intermediate product to water in the intermediate product dispersion is preferably 0.5 g: 40–100 mL. In this invention, the water is preferably deionized water. In this invention, it is preferable to add a cobalt-based compound to the intermediate product aqueous dispersion and continuously stir to obtain a mixture. In this invention, the stirring time is preferably ≥4 h.

[0080] After centrifugation, the present invention preferably further includes washing the precipitate collected after centrifugation with water. In the present invention, the washing is preferably done with deionized water, and the number of washing cycles is preferably ≥3. In the present invention, it is preferable to calcine the washed precipitate.

[0081] In this invention, the calcination is preferably carried out in air. In this invention, the heating rate to the calcination temperature is preferably 1–2 °C / min. In this invention, the calcination temperature is preferably 400–800 °C, more preferably 400–600 °C; the calcination time is preferably 2–4 h, more preferably 2–3 h.

[0082] Figure 1The synthesis flow chart for the single-atom Co-anchored TiO2 catalyst in Example 1 is as follows: In this invention, a dicarboxylic acid is mixed with organotitanium and subjected to a thermal reaction to obtain the MIL-125 precursor. It can be seen that the obtained MIL-125 precursor has a regular and uniform cake-like morphology. The MIL-125 precursor is then mixed with tannic acid and subjected to a hydrothermal etching reaction. When using tannic acid for hydrothermal etching of the MIL-125 precursor, the etching process begins from the internal center of the MIL-125 precursor, followed by external collapse. The resulting intermediate product has a blood cell shape, which has a larger specific surface area, facilitating the adsorption and exposure of more cobalt single atoms. During the hydrothermal etching reaction, the overall size of the MIL-125 precursor or intermediate product remains essentially unchanged, and the MIL-125 precursor is pre-oxidized and converted into TiO2 during the reaction. Pre-oxidation helps stabilize the structure of the intermediate product, preventing excessive collapse into fragments during subsequent calcination. The intermediate product of red blood cell type TiO2 is mixed with cobalt-based compounds. After calcination, the central region collapses further, eventually forming a donut-like shape with cobalt single atoms dispersed on the surface of nano TiO2.

[0083] This invention also provides the application of the single-atom Co-anchored TiO2 catalyst described in the above technical solution or the single-atom Co-anchored TiO2 catalyst prepared by the above preparation method in the removal of organic pollutants in water.

[0084] In this invention, the organic pollutant preferably includes a plasticizer. In this invention, the plasticizer is preferably a phthalate plasticizer, and more preferably dibutyl phthalate.

[0085] In this invention, the specific application of the single-atom Co-anchored TiO2 catalyst in removing organic pollutants from water includes the following steps:

[0086] TiO2 catalyst anchored to single-atom Co, persulfate, and wastewater to be treated were mixed and subjected to phototreatment under visible light.

[0087] In this invention, the light source for the light processing is preferably a xenon lamp, and the output current is preferably 50-80A.

[0088] In this invention, the persulfate preferably includes one or more of potassium persulfate, potassium peroxymonosulfate, potassium peroxydisulfate, sodium persulfate, and sodium peroxymonosulfate. More preferably, the persulfate includes one or more of potassium peroxymonosulfate and potassium persulfate.

[0089] In this invention, the amount of the single-atom Co-anchored TiO2 catalyst is preferably 0.2–2 g / L, more preferably 0.4–0.5 g. In this invention, the amount of persulfate is preferably 0.3–3 g / L, more preferably 0.5–1 g / L.

[0090] In this invention, the pH value of the wastewater to be treated is preferably 3 to 12, and more preferably 4 to 10.

[0091] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0092] Example 1

[0093] (1) Dissolve 3g of terephthalic acid in 54mL of DMF and stir for 30min to obtain a terephthalic acid solution;

[0094] (2) Dissolve 1.56 mL of tetrabutyl titanate in 6 mL of methanol and stir for 30 min to obtain a tetrabutyl titanate methanol solution.

[0095] (3) The obtained tetrabutyl titanate methanol solution was quickly added to the terephthalic acid solution. After stirring for 10 min, the resulting mixed solution was transferred to a polytetrafluoroethylene reactor for thermal reaction at a temperature of 150℃ for 24 h.

[0096] (4) The reaction solution was centrifuged to collect the white product. The white product was washed three times with DMF, and then washed three times with methanol. The white product was dried in a 60°C oven for 12 hours, ground at a mesh size of 200, and collected to obtain the MIL-125 precursor (i.e. Figure 8 MIL-125 in the middle);

[0097] (5) Disperse 1g of the obtained MIL-125 precursor in 50mL of deionized water to obtain a MIL-125 precursor dispersion; add 1g of tannic acid to the MIL-125 precursor dispersion, stir for 20min, and then transfer the mixed dispersion to a polytetrafluoroethylene reactor for hydrothermal etching reaction. The temperature of the hydrothermal etching reaction is 150℃ and the time is 2h.

[0098] (6) Centrifuge the solution after the hydrothermal etching reaction to collect the brown product. Wash the brown substance three times with deionized water, dry the brown substance in a 60℃ oven for 12 hours, grind it, and collect it to obtain the intermediate product (i.e. Figure 8 E-TiO2 in the middle);

[0099] (7) Disperse 500 mg of the obtained intermediate product in 50 mL of deionized water, add 20 mg of cobalt nitrate, stir continuously for 4 h, centrifuge the mixture, and collect the precipitate (i.e., Figure 8 The Co-E-TiO2 in the sample was washed with deionized water three times;

[0100] (8) The obtained precipitate was transferred to a crucible and calcined in air at a heating rate of 1℃ / min to a calcination temperature of 400℃, and held for 2h to obtain a single-atom Co-anchored TiO2 catalyst (i.e., Figure 8 Co in SA -TiO2).

[0101] Figure 2 The image shows a SEM image of the MIL-125 precursor prepared in Example 1. Figure 2 As can be seen, the MIL-125 precursor has a regular and uniform disc-shaped morphology with a diameter of 500-700 nm and a thickness of 300-400 nm.

[0102] Figure 3 This is a TEM image of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 3 As can be seen, the morphology of the obtained single-atom Co-anchored TiO2 catalyst is donut-shaped, with an outer diameter of 500-700 nm, an inner diameter of 50-300 nm, and a thickness of 300-400 nm along the normal of the nano-TiO2.

[0103] Figure 4 The image shown is a HAADF-STEM image of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 4 Figure a in the image is a HAADF-STEM image of a high-angle annular dark-field HAADF mode image from STEM. Figure 4 As can be seen in Figure a, clear and bright contrast points are visible on the Ti atom array. Figure 4 (within the red circle in figure a) This is due to the fact that Co atoms have a larger atomic mass than Ti atoms, so they appear larger and brighter; Figure 4 Figure b in the diagram is the fitted HAADF-STEM image, which provides a more intuitive comparison compared to figure a. Figure 4 In diagram c, the purple background represents Ti atoms, while the red areas are clearer and brighter contrast points, representing Co atoms.

[0104] Figure 5 This is a line scan image of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 5It can be seen that the linear scan results show both Ti and Co atoms, with Co having a stronger signal. At the same time, the catalyst contains a large number of defects, which is beneficial for the subsequent separation of hole-electron pairs.

[0105] Figure 6 The internal strain diagram of the single-atom Co-anchored TiO2 catalyst prepared in Example 1 is shown. Figure 6 Figure a in the image shows the HAADF-STEM image of the TiO2 catalyst anchored by a single atom Co. Figure 6 Figure b in the diagram is calculated using geometrical phase analysis (GPA). Figure 6 The analysis of the internal strain in figure a shows that: Figure 6 Geometric phase analysis of diagram b in the figure determines the shear component (ε) xy The corresponding strain distribution of Co is determined by geometric phase analysis (GPA). SA - HAADF-STEM images of TiO2 show the internal strain of selected regions to better illustrate the strain on the catalyst surface. Lattice variations provide a quantitative assessment of the compressive strain at specific locations on the surface-modified, single-atom Co-anchored TiO2 catalyst, and the corresponding strain distribution further illustrates this. From... Figure 6 The enormous internal strain can be clearly observed in diagram b. Figure 6 A distinct blue patch appears at the top of graph b, corresponding to a negative strain location, illustrating the various strains at that site. The red area at the bottom indicates significant stretching at that location. Due to strain engineering altering the electronic structure, the unsaturation of the Co sites is further exacerbated.

[0106] Figure 7 The image shows the XRD pattern of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 7 It can be seen that the diffraction peaks of the synthesized MIL-125 are consistent with the characteristic peaks of typical MIL-125, indicating that the MIL-125 precursor was successfully synthesized. Red blood cell-type TiO2 was then reacted with a series of single-atom Co-anchored TiO2 catalysts. SA Comparing the TiO2 samples, the peaks at 25.3°, 37.8°, 48.0°, 55.1°, and 52.7° correspond to the (101), (004), (200), (211), and (204) crystal planes of TiO2, respectively. This result is consistent with JCPDS:21-1272. The absence of a Co signal in the XRD pattern indicates that the TiO2 catalyst anchored by single-atom Co does not contain any Co-containing crystal planes, further proving that Co exists in the catalyst in the form of single atoms.

[0107] Figure 8The image shows the FT-IR spectrum of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 8 It can be seen that the synthesized erythrocyte-type TiO2 ( Figure 8 The E-TiO2 in the catalyst still retains most of the functional groups of the MIL-125 precursor, and there is no significant difference before and after etching. Single-atom Co-anchored TiO2 catalyst ( Figure 8 Co in SA -TiO2) at 690cm -1 The surrounding area exhibits a relatively wide low-frequency band, mainly due to the vibrations of Ti-O-Ti and Ti-O.

[0108] Figure 9 The image shows the XPS plot of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 9 Figure a in the diagram is the Co2p diagram, from... Figure 9 As can be seen from Figure a: Co 2+ The energy spectrum peaks appear at 780.2 eV and 795.2 eV, and its satellite peaks appear at 786.8 eV and 802.7 eV. Figure 9 The b-plot in the image is an O1s plot, from... Figure 9 As shown in Figure b, the O1s spectrum exhibits a broad asymmetric peak, which can be deconvoluted at 529.3, 530, and 531.3 eV into three distinct peaks, corresponding to lattice oxygen (L...). O Hole oxygen (V) O ) and chemically adsorbed oxygen (C O This indicates that the TiO2 catalyst with Co anchored by a single atom is Co. SA -TiO2 has a large amount of V O This not only leads to an increase in electron density around Ti sites, but also facilitates the separation of electron-hole pairs during photocatalysis due to the presence of defects.

[0109] Figure 10 The image shows the XANES plot of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 10 It can be seen that: TiO2 catalysts anchored by single-atom Co have Co content. SA The absorption edge of TiO2 is located between the Co foil and CoO, indicating that the TiO2 catalyst with single-atom Co anchoring exhibits Co... SA In TiO2, the valence state of Co atoms ranges from 0 to +2. SA The CoO absorption edge of TiO2 is closer to CoO than to the Co foil, indicating that a single Co atom carries a positive charge and has a valence state close to +2.

[0110] Figure 11The image shows the EXAFS plot of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 11 It can be seen that the coordination environment of Co sites varies in different Co compounds. Co foil in... There is a distinct peak at 1.8, which is due to the effect of Co-Co bonds. CoO at 1.8 and... There are two peaks, which are related to Co-O and Co-Co coordination, respectively. Single-atom Co-anchored TiO2 catalyst Co SA The TiO2 spectrum shows only Co-O coordination and no Co-Co bonds, indicating the absence of Co or CoO clusters / particles, which further confirms the atomic dispersion of Co.

[0111] Figure 12 This is a two-dimensional color patch diagram of the EXAFS spectrum of the single-atom Co-anchored TiO2 catalyst prepared in Example 1. Figure 12 Figure a shows a two-dimensional color block diagram of the Co foil, Figure b shows a two-dimensional color block diagram of CoO, and Figure c shows a two-dimensional color block diagram of the TiO2 catalyst anchored by single-atom Co. By comparison, it can be seen from the figures that: compared with the wavelet-transformed reference contour maps of the Co foil and CoO, the TiO2 catalyst anchored by single-atom Co is found to have Co... SA The absence of Co-Co coordination peaks in TiO2 confirms that the Co species are strictly separated, thus demonstrating that the TiO2 catalyst is anchored by a single atom of Co. SA In TiO2, Co exists in the form of single atoms.

[0112] Example 2

[0113] (1) Dissolve 3.27g of 2-aminoterephthalic acid in 54mL of DMF and stir for 30min to obtain a 2-aminoterephthalic acid solution;

[0114] (2) Dissolve 1.56 mL of tetrabutyl titanate in 6 mL of methanol and stir for 30 min to obtain a tetrabutyl titanate methanol solution.

[0115] (3) The obtained tetrabutyl titanate methanol solution was quickly added to the 2-aminoterephthalic acid solution. After stirring for 10 min, the resulting mixed solution was transferred to a polytetrafluoroethylene reactor for thermal reaction at a temperature of 120℃ for 24 h.

[0116] (4) Centrifuge the liquid after thermal reaction, collect the white product, wash the white product with DMF 3 times, then wash the white product with methanol 3 times, dry the white product in an oven at 60℃ for 12h, grind it at 200 mesh and collect it to obtain the MIL-125 precursor.

[0117] (5) Disperse 1g of the obtained MIL-125 precursor in 50mL of deionized water to obtain a MIL-125 precursor dispersion; add 1.2g of tannic acid to the MIL-125 precursor dispersion, stir for 20min, and then transfer the mixed dispersion to a polytetrafluoroethylene reactor for hydrothermal etching reaction. The hydrothermal etching reaction temperature is 120℃ and the time is 2h.

[0118] (6) Centrifuge the liquid after hydrothermal etching reaction, collect the brown product, wash the brown substance three times with deionized water, dry the brown substance in an oven at 60°C for 12 hours, grind and collect to obtain the intermediate product.

[0119] (7) Disperse 500 mg of the intermediate product in 50 mL of deionized water, add 30 mg of cobalt nitrate, stir continuously for 4 h, centrifuge the mixture, collect the precipitate, and wash the precipitate 3 times with deionized water.

[0120] (8) The obtained precipitate was transferred to a crucible and calcined in air at a heating rate of 1 °C / min to a calcination temperature of 600 °C, and held for 2 h. After cooling to room temperature, a single-atom Co-anchored TiO2 catalyst was obtained.

[0121] Example 3

[0122] (1) Dissolve 3g of terephthalic acid in 54mL of DMF and stir for 30min to obtain a terephthalic acid solution;

[0123] (2) Dissolve 1.25 mL of tetraisopropyl titanate in 6 mL of methanol and stir for 30 min to obtain a tetraisopropyl titanate methanol solution.

[0124] (3) The obtained tetraisopropyl titanate methanol solution was quickly added to the terephthalic acid solution. After stirring for 10 min, the resulting mixed solution was transferred to a polytetrafluoroethylene reactor for thermal reaction. The temperature of the thermal reaction was 180℃ and the time was 24 h.

[0125] (4) Centrifuge the liquid after thermal reaction, collect the white product, wash the white product with DMF 3 times, then wash the white product with methanol 3 times, dry the white product in an oven at 60℃ for 12h, grind it at 200 mesh and collect it to obtain the MIL-125 precursor.

[0126] (5) Disperse 1g of the obtained MIL-125 precursor in 50mL of deionized water to obtain a MIL-125 precursor dispersion; add 1.2g of tannic acid to the MIL-125 precursor dispersion, stir for 20min, and then transfer the mixed dispersion to a polytetrafluoroethylene reactor for hydrothermal etching reaction. The hydrothermal etching reaction temperature is 180℃ and the time is 2h.

[0127] (6) Centrifuge the liquid after hydrothermal etching reaction, collect the brown product, wash the brown substance three times with deionized water, dry the brown substance in an oven at 60°C for 12 hours, grind and collect to obtain the intermediate product.

[0128] (7) Disperse 500 mg of the intermediate product in 50 mL of deionized water, add 20 mg of cobalt chloride, stir continuously for 4 h, centrifuge the mixture, collect the precipitate, and wash the precipitate 3 times with deionized water.

[0129] (8) The obtained precipitate was transferred to a crucible and calcined in air at a heating rate of 1 °C / min to a calcination temperature of 600 °C, and held for 2 h. After cooling to room temperature, a single-atom Co-anchored TiO2 catalyst was obtained.

[0130] Example 4

[0131] (1) Dissolve 3.27g of 2-aminoterephthalic acid in 54mL of DMF and stir for 30min to obtain a 2-aminoterephthalic acid solution;

[0132] (2) Dissolve 1.25 mL of tetraisopropyl titanate in 6 mL of methanol and stir for 30 min to obtain a tetraisopropyl titanate methanol solution.

[0133] (3) The obtained tetraisopropyl titanate methanol solution was quickly added to the 2-aminoterephthalic acid solution. After stirring for 10 min, the resulting mixed solution was transferred to a polytetrafluoroethylene reactor for thermal reaction at a temperature of 150 °C for 18 h.

[0134] (4) Centrifuge the liquid after thermal reaction, collect the white product, wash the white product with DMF 3 times, then wash the white product with methanol 3 times, dry the white product in an oven at 60℃ for 12h, grind it at 200 mesh and collect it to obtain the MIL-125 precursor.

[0135] (5) Disperse 1g of the obtained MIL-125 precursor in 50mL of deionized water to obtain a MIL-125 precursor dispersion; add 1.5g of tannic acid to the MIL-125 precursor dispersion, stir for 20min, and then transfer the mixed dispersion to a polytetrafluoroethylene reactor for hydrothermal etching reaction. The temperature of the hydrothermal etching reaction is 150℃ and the time is 6h.

[0136] (6) Centrifuge the liquid after hydrothermal etching reaction, collect the brown product, wash the brown substance three times with deionized water, dry the brown substance in an oven at 60°C for 12 hours, grind and collect to obtain the intermediate product.

[0137] (7) Disperse 500 mg of the intermediate product in 50 mL of deionized water, add 20 mg of cobalt acetate, stir continuously for 4 h, centrifuge the mixture, collect the precipitate, and wash the precipitate 3 times with deionized water.

[0138] (8) The obtained precipitate was transferred to a crucible and calcined in air at a heating rate of 1 °C / min to a calcination temperature of 400 °C, and held for 4 h. After cooling to room temperature, a single-atom Co-anchored TiO2 catalyst was obtained.

[0139] Comparative Example 1

[0140] The difference from Example 1 is that tannic acid was not added and hydrothermal etching was not performed.

[0141] (1) Dissolve 3g of terephthalic acid in 54mL of DMF and stir for 30min to obtain a terephthalic acid solution;

[0142] (2) Dissolve 1.56 mL of tetrabutyl titanate in 6 mL of methanol and stir for 30 min to obtain a tetrabutyl titanate methanol solution.

[0143] (3) The obtained tetrabutyl titanate methanol solution was quickly added to the terephthalic acid solution. After stirring for 10 min, the resulting mixed solution was transferred to a polytetrafluoroethylene reactor for thermal reaction at a temperature of 150℃ for 24 h.

[0144] (4) Centrifuge the liquid after thermal reaction, collect the white product, wash the white product with DMF 3 times, then wash the white product with methanol 3 times, dry the white product in an oven at 60℃ for 12h, grind it at 200 mesh and collect it to obtain the MIL-125 precursor.

[0145] (5) Disperse 1g of the obtained MIL-125 in 50mL of deionized water, add 20mg of cobalt nitrate, stir continuously for 4h, centrifuge the mixture, collect the precipitate, and wash the precipitate 3 times with deionized water.

[0146] (6) The obtained precipitate was transferred to a crucible and calcined in air at a heating rate of 1 °C / min to a calcination temperature of 400 °C, and held for 2 h. A single-atom Co-anchored TiO2 catalyst was obtained.

[0147] Application Example 1

[0148] 10 mg of dibutyl phthalate (DBP) and 50 mL of deionized water were added to a beaker to simulate wastewater with a pH of 5.71. Then, 20 mg of the catalyst obtained in Example 1 was added, and the mixture was placed in the dark and subjected to adsorption for 30 min under continuous stirring. After that, 25 mg of potassium persulfate (PMS) was added and the mixture was stirred continuously until homogeneous to obtain the reaction solution.

[0149] Turn on the xenon lamp light source with a filter (UVCUT400) (equipment type: Microsolar300) and treat the beaker containing the reaction solution under visible light for 30 minutes.

[0150] Add 2 mg Na2S2O3·5H2O to a 2 mL glass centrifuge tube to quench free radicals and terminate the reaction; add 1 mL of the reaction solution to the centrifuge tube every 5 min, and place the centrifuge tube in a shaker and stir for 10 s.

[0151] The glass centrifuge tube was centrifuged at 2500 r / min to obtain the supernatant and the lower layer solution.

[0152] DBP degradation rate test: The supernatant was placed in a brown sample bottle, and the DBP content in the reaction solution was detected by high performance liquid chromatography and standard sample-linear regression method. The degradation rate of DBP of the single-atom Co-anchored TiO2 catalysts obtained in Examples 1-4 and Comparative Example 1 was detected respectively. The test results are shown in Table 1.

[0153] Co ion leaching concentration test: 20 mL of the reaction solution after being treated with visible light for 30 min was taken, and the concentration of Co ions leached into the reaction solution was detected using inductively coupled plasma optical emission spectrometry (ICP). The leaching concentration of Co ions from the TiO2 catalyst with single-atom Co anchoring obtained in the examples and comparative examples was verified according to Application Example 1. The detection results are shown in Table 1.

[0154] Co loading test: 20 mg of the single-atom Co-anchored TiO2 catalyst obtained in the examples and comparative examples was placed in a beaker, and 5 mL of aqua regia was added for digestion. After digestion, deionized water was added to dilute to 50 mL. 20 mL of the diluted digestion solution was taken, and the concentration of leached Co ions was detected by inductively coupled plasma optical emission spectrometry (ICP). The Co loading on the single-atom Co-anchored TiO2 catalyst was calculated. The test results are shown in Table 1.

[0155] Specific surface area test: 100 mg of the single-atom Co-anchored TiO2 catalyst obtained in the examples and comparative examples was taken, and the specific surface area was detected using a fully automated surface area and pore size distribution analyzer. The specific surface area of ​​the single-atom Co-anchored TiO2 catalyst was obtained. The test results are shown in Table 1.

[0156] Table 1. Test results of single-atom Co-anchored TiO2 catalysts obtained in the examples and comparative examples.

[0157]

[0158] As can be seen from Table 1, the TiO2 catalyst with single-atom Co anchoring prepared in Example 1 has the best performance, while the catalyst prepared in Comparative Example 1 without etching has a much lower Co loading and degradation efficiency than that of Example 1.

[0159] The specific surface area of ​​the single-atom Co-anchored TiO2 catalyst obtained by this invention is 100–150 m². 2 / g, while commercially available P 25 The specific surface area of ​​TiO2 is generally 60 m². 2 / g.

[0160] Application Example 2

[0161] The difference from Application Example 1 is that the pH values ​​of the simulated wastewater were adjusted to 2, 4, 5.71, 8 and 10 respectively, and samples were taken to detect the Co leaching concentration and DBP degradation rate. The test results are shown in Table 2.

[0162] Table 2. Test results under different pH conditions

[0163]

[0164]

[0165] Table 2 shows that the single-atom Co-anchored TiO2 catalyst Co prepared in this invention... SA -TiO2 has good pH adaptability and good degradation effect over a wide range, but under strongly acidic conditions, the catalyst performance will deteriorate due to the leaching of Co.

[0166] Figure 13 To illustrate the effect of different pH conditions on the degradation of DBP, a line graph of the DBP degradation rate under different pH conditions was used in Example 2. Figure 13 It can be seen that the pH of the solution is an important factor affecting advanced oxidation and one of the main limiting factors in practical water applications. Analysis of the DBP degradation effect within the pH range of 2–10 shows that the degradation efficiency decreases slightly under weakly acidic conditions (pH = 4), with a reaction rate of 0.1207 min. -1 However, under extremely acidic conditions (pH=2), the reaction was significantly inhibited, possibly due to the detachment of Co anchored to the catalyst. Excess H₂... + The ions form strong hydrogen bonds with the peroxy (-OO-) bonds in potassium persulfate PMS, thereby minimizing the generation of reactive free radicals in the medium. At lower pH values, the mother acid H₂SO₅ will replace HSO₅. - Persulfate becomes the main substance and also interferes with Co. 2+ To Co 3+ The conversion pathway was observed. Under alkaline conditions (pH = 8, 10), the degradation efficiency did not change significantly, indicating that the catalyst also exhibits good stability under strongly alkaline conditions. Furthermore, under conditions of pH > 9.5, HSO5... - It will turn into SO5 2- The latter produces SO4 2- It is more effective than the former. Since extreme pH conditions are usually not achieved in real-world water bodies, the single-atom Co-anchored TiO2 catalyst Co prepared in this invention... SA TiO2 can be used in most water bodies.

[0167] Application Example 3

[0168] The single-atom Co-anchored TiO2 catalyst obtained in Example 1 was subjected to eight repeated tests of dibutyl phthalate (DBP) degradation rate according to Application Example 1. In the first three repeated degradation tests, the single-atom Co-anchored TiO2 catalyst was centrifuged and recovered, then washed three times with deionized water and dried for reuse. After the fourth reuse, the recovered single-atom Co-anchored TiO2 catalyst was washed three times with deionized water, placed in a reactor at 400°C, calcined again for 30 minutes, cooled to room temperature, and then subjected to repeated DBP degradation tests. The degradation rate of DBP and the Co leaching concentration of the catalyst in each reuse were measured, and the results are shown in Table 3.

[0169] Table 3. Test results of reusable single-atom Co-anchored TiO2 catalysts

[0170]

[0171]

[0172] As can be seen from Table 3, the single-atom Co-anchored TiO2 catalyst Co prepared in this invention... SA -TiO2 has good recycling performance, can be reused, and is economical.

[0173] Figure 14 To illustrate the degradation rate of DBP under repeated catalyst conditions in Example 3, a bar chart is used to visually demonstrate the degradation effect of each cycle on DBP. Figure 14 It can be seen that the cyclicity of a catalyst directly affects its economic applicability in practical applications and can directly reflect the stability of the material. The single-atom Co-anchored TiO2 catalyst Co prepared in this invention... SA After eight cycles of reuse, the TiO2 catalyst maintained a DBP degradation efficiency of 96.061%, demonstrating its excellent stability. In the first three cycles, catalyst recovery involved simple washing and drying, which easily led to the active sites being covered by degradation intermediates. Therefore, from the fourth cycle onwards, the single-atom Co-anchored TiO2 catalyst... SA After cleaning, the TiO2 was calcined at 400℃ for 30 min to restore the catalyst performance. In repeated DBP degradation tests, the leaching concentration of Co in the single-atom Co-anchored TiO2 catalyst was <0.2 mg / L in the third cycle and <0.1 mg / L in the fourth to eighth cycles. The leaching concentration of Co remained stable at a low level, indicating that the loss of Co was very small and the Co atoms anchored on TiO2 had high stability. After one cycle, the loss of Co was only about 2%, which proves that the single-atom Co-anchored TiO2 catalyst prepared in this invention has excellent stability.

[0174] Application Comparative Example 1

[0175] The difference from Application Example 1 is that the single-atom Co-anchored TiO2 catalyst obtained in Example 1 was not added, and visible light was not used.

[0176] The degradation rate of DBP was 10.806%.

[0177] Application Comparative Example 2

[0178] The difference from Application Example 1 is that potassium persulfate (PMS) was not added, and visible light was not used.

[0179] The degradation rate of DBP was 0.929%.

[0180] Application Comparative Example 3

[0181] The difference from Application Example 1 is that the single-atom Co-anchored TiO2 catalyst obtained in Example 1 was not added.

[0182] The degradation rate of DBP was 48.058%.

[0183] Application Comparative Example 4

[0184] The difference from Application Example 1 is that potassium persulfate (PMS) was not added.

[0185] The degradation rate of DBP was 12.745%.

[0186] Application Comparative Example 5

[0187] The difference from application example 1 is that visible light was not used.

[0188] The degradation rate of DBP was 95.68%.

[0189] Application Comparative Example 6

[0190] The difference from Application Example 1 is that the concentration of Cl was controlled at 0.05 mol / L in different glass centrifuge tubes. - SO4 2- NO3 - and HPO4 2- / H2PO4 - The degradation rate of DBP was measured by sampling, and the test results are shown in Table 4.

[0191] Table 4. Test results of the effect of different anions on DBP degradation rate

[0192] sample DBP degradation rate, % <![CDATA[Cl - ]]> 32.692 <![CDATA[SO4 2- ]]> 100 <![CDATA[NO3 - ]]> 100 <![CDATA[HPO4 2- / H2PO4 - ]]> 100

[0193] As can be seen from Table 4: Cl - The presence of SO4 resulted in a final degradation rate of only 32.69% for dibutyl phthalate (DBP). 2- NO3 - and HPO4 2- / H2PO4 - It has virtually no impact on the degradation rate of DBP.

[0194] Figure 15 To visually demonstrate the degradation effect of different anions on DBP using line graphs of DBP degradation rates under different anionic conditions in Comparative Example 3, we... Figure 15 It can be seen that the influence of common anions in water on DBP degradation was investigated, and Cl... - Ions often interfere with the generation of free radicals in TiO2 catalysts anchored by single atoms of Co, thereby affecting the degradation efficiency of the organic pollutant dibutyl phthalate (DBP). 2- NO3 -and HPO4 2- / H2PO4 - It has virtually no effect on the reaction, SO4 2- Easily affected by halide ions (such as Cl) - It scavenges and generates chlorine free radicals. Chlorine free radicals have low redox potentials and can react with organic matter to form insoluble chlorides. Therefore, Cl... - The presence of these substances usually exhibits an inhibitory effect, leading to a significant reduction in the degradation efficiency of the catalyst.

[0195] Figure 16 Line graphs showing the degradation rates of DBP in Application Example 1 and Comparative Examples 1-5 visually demonstrate the degradation effect of Application Example 1 and Comparative Examples 1-5 on dibutyl phthalate (DBP). Figure 16 It can be seen that the single-atom Co-anchored TiO2 catalyst Co prepared in this invention SA - The adsorption and degradation effect of TiO2 on dibutyl phthalate (DBP). TiO2 catalyst with single-atom Co anchoring and Co... SA After the adsorption process of DBP by TiO2 stabilized, the degradation rate of DBP in Comparative Example 2 was only 0.929%. Comparative Example 1, without adding a catalyst or using visible light, achieved a DBP degradation rate of 10.806%. After adding visible light irradiation, Comparative Example 3 reached 48.058%. This demonstrates that the single-atom Co-anchored TiO2 catalyst Co prepared in this invention... SA The synergistic system of TiO2 and peroxymonosulfate (PMS) significantly increased the degradation effect of dibutyl phthalate (DBP), but still could not achieve complete degradation of DBP. Comparative Example 5, which did not use visible light, achieved a final degradation rate of 95.68%, indicating that the single-atom Co-anchored TiO2 catalyst... SA Based on the synergistic system of TiO2 and peroxymonosulfate (PMS), the addition of visible light irradiation enhances the photocatalysis and single-atom Co-anchored TiO2 catalyst Co. SA The combined effect of TiO2 and peroxymonosulfate PMS synergistic system resulted in a 100% final degradation rate of dibutyl phthalate (DBP) within 30 minutes.

[0196] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of a single-atom Co-anchored TiO2 catalyst in the removal of organic pollutants from water, characterized in that, The organic pollutants include plasticizers; The single-atom Co-anchored TiO2 catalyst comprises nano-TiO2 and single-atom Co; The single-atom Co is dispersed on the surface of the nano-TiO2; The loading of the single-atom Co is 0.1~1wt%, and the remainder is nano-TiO2; The nano-TiO2 is donut-shaped, with an outer diameter of 500-700 nm, an inner diameter of 50-300 nm, and a thickness of 300-400 nm along the normal direction of the nano-TiO2; the specific surface area of ​​the nano-TiO2 is 100-150 m² / g. 2 / g; The preparation method of the single-atom Co-anchored TiO2 catalyst includes the following preparation steps: Dicarboxylic acid and organotitanium were mixed and subjected to a thermal reaction to obtain the MIL-125 precursor. The MIL-125 precursor was mixed with tannic acid and subjected to a hydrothermal etching reaction to obtain an intermediate product; the mass ratio of the MIL-125 precursor to tannic acid was 1:0.5~3; the temperature of the hydrothermal etching reaction was 100~200℃ and the reaction time was 1~4h. The intermediate product was mixed with a cobalt-based compound and then calcined to obtain the single-atom Co-anchored TiO2 catalyst.

2. The application according to claim 1, characterized in that, The dicarboxylic acid includes terephthalic acid or 2-aminoterephthalic acid; The organic titanium is tetrabutyl titanate or tetraisopropyl titanate; The cobalt-based compound is cobalt nitrate, cobalt chloride, or cobalt acetate.

3. The application according to claim 1 or 2, characterized in that, The mass ratio of the dicarboxylic acid to the organotitanium is 2~5:1~3; The thermal reaction is carried out at a temperature of 120-180°C for 12-24 hours.

4. The application according to claim 1, characterized in that, The mass ratio of the intermediate product to the cobalt-based compound is 500~1000:5~50; the calcination temperature is 400~800℃, and the calcination time is 2~4h.

5. The application according to claim 1, characterized in that, The method of applying the single-atom Co-anchored TiO2 catalyst to remove organic pollutants from water includes the following steps: TiO2 catalyst anchored to single-atom Co, persulfate, and wastewater to be treated were mixed and subjected to phototreatment under visible light.

6. The application according to claim 5, characterized in that, The persulfate includes one or more of potassium persulfate, potassium persulfate, potassium persulfate, sodium persulfate, and sodium persulfate. The amount of the single-atom Co-anchored TiO2 catalyst used is 0.2~2 g / L; The amount of persulfate used is 0.3~3 g / L; The pH value of the wastewater to be treated is 3~12.

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