A supported S,N co-doped TiO2 visible light photocatalyst, its preparation method and applications

Abstract

The application provides a supported S, N co-doped TiO2 visible light catalyst and a preparation method and application thereof, and belongs to the field of visible light catalytic degradation of dye wastewater.The visible light catalyst of the application takes cellulose colloid as a carrier, and then S, N co-doped titanium oxide is prepared through a hydrothermal reaction.The supported S, N co-doped TiO2 visible light catalyst of the application has a wide band gap, shows good photocatalytic activity under visible light irradiation, is biologically non-toxic, has excellent stability, has excellent degradation capacity for dye wastewater, can be applied to degradation of dye wastewater, and has very excellent application prospect.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic degradation of dye wastewater, specifically relating to a supported S,N co-doped TiO2 visible light catalyst, its preparation method, and its applications. Background Technology

[0002] With rapid industrialization and urbanization, and the continuous increase in the world's population, global water pollution has become increasingly severe, with synthetic dyes posing a particularly prominent threat. Synthetic dyes, due to their bright colors and low cost, are widely used in various industrial sectors such as textiles, cosmetics, clothing, food, papermaking, rubber, printing, and plastics. However, the large-scale use and discharge of synthetic dyes in these industrial production processes has become one of the main factors causing water pollution. According to relevant statistics, hundreds of thousands of tons of dye wastewater are discharged into the environment globally each year without adequate treatment, causing serious damage to aquatic ecosystems and threatening the survival of aquatic life and human health.

[0003] Photocatalytic treatment technology has attracted widespread attention in the field of dye-polluted wastewater treatment due to its numerous significant advantages. This technology utilizes the strong oxidizing substances generated by photocatalysts under light conditions to effectively degrade dye molecules into harmless small molecules such as carbon dioxide and water, thereby purifying dye wastewater. Compared with traditional wastewater treatment methods, photocatalytic treatment technology has advantages such as being environmentally friendly, requiring no chemical reagents, and generating no secondary waste, while also exhibiting high treatment efficiency and broad application prospects. However, traditional photocatalysts, such as simple titanium dioxide (TiO2) and zinc oxide (ZnO), have some drawbacks that limit their widespread application. These traditional photocatalysts have large band gaps (typically greater than 3.0 eV) and can only be activated by ultraviolet light, which accounts for only about 4% of the solar spectrum. This means that traditional photocatalysts have significant limitations in utilizing solar energy, resulting in low quantum efficiency and hindering large-scale industrial applications, thus limiting the further promotion of photocatalytic treatment technology in the field of dye-polluted wastewater treatment.

[0004] In recent years, photocatalysis technology has developed rapidly. Researchers are dedicated to synthesizing highly efficient photocatalysts with solar energy collection capabilities to improve the practicality and economy of photocatalytic treatment technologies. To extend the photoresponse range of photocatalysts and enable them to utilize the visible light portion of sunlight more effectively, researchers have explored various methods, including doping with non-metallic elements, depositing noble metals, and constructing heterostructures. For example, doping with non-metallic elements reduces the band gap of photocatalysts, thereby improving their absorption capacity for visible light; depositing noble metal nanoparticles (such as platinum and silver) on the surface of photocatalysts can create localized surface plasmon resonance effects, enhancing the light absorption performance of photocatalysts; constructing heterostructures, which combines two or more semiconductor materials with different band structures, can achieve effective separation and transfer of photogenerated carriers, improving photocatalytic efficiency. All three methods have drawbacks. For example, doping with non-metallic elements does not significantly improve catalytic performance. For heterostructure photocatalysts, although they can effectively promote the separation of photogenerated carriers, the interfacial charge transport efficiency between different semiconductor materials is still low. While noble metals (such as platinum Pt and silver Ag) can significantly improve the performance of photocatalysts, their high cost limits large-scale industrial applications, and precious metal resources are limited, making it difficult to meet the growing environmental protection demands.

[0005] For example, patent CN116747897B discloses a method of achieving sulfur and nitrogen co-doping by immobilizing nitrogen on a silicon-oxygen framework; patent CN106268904B discloses a sulfur / nitrogen / phosphorus co-doped titanium dioxide photocatalyst and its application in algae degradation; and patent application CN 114749167A discloses a bulk N / S-TiO2 material and its application in formaldehyde photocatalytic degradation. Currently, there are no reports on S / N co-doped photocatalysts improving the degradation capacity of dye wastewater. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention constructs a supported S,N co-doped TiO2 visible light catalyst by designing a novel supported non-metallic S,N co-doped structure and optimizing bandgap matching and interface charge separation.

[0007] This invention provides a supported S,N co-doped TiO2 visible light catalyst for degrading dye wastewater. The catalyst is prepared by reacting tetrabutyl titanate, thioacetic acid, N,N-diisopropylethylamine and cellulose microspheres to obtain S,N co-doped TiO2 cellulose microspheres, wherein the total molar amount of S and N to the molar percentage of TiO2 is 11%, the molar ratio of S / N is 1:4, and the mass ratio of TiO2 to cellulose microspheres is 17:40. The catalyst is prepared by the following method: (1) cellulose microspheres are uniformly dispersed in anhydrous ethanol to obtain a dispersion; (2) tetrabutyl titanate, thioacetic acid and N,N-diisopropylethylamine are slowly added to the aforementioned dispersion under stirring, and then glacial acetic acid solution is added dropwise to obtain a mixed solution. (3) Transfer the mixture into a sealed container and carry out a solvothermal reaction. After the reaction is completed, cool to room temperature, filter, wash, and dry to obtain the final product.

[0008] Furthermore, the aforementioned cellulose microspheres were prepared according to the following method: 1) Add cellulose to a mixed solution of sodium hydroxide, polyethylene glycol and deionized water, cool to -20°C, and stir vigorously until a transparent solution A is obtained; 2) Emulsify and disperse the paraffin oil in a deionized aqueous solution containing an emulsifier to obtain suspension B; 3) Slowly add solution A to suspension B, stir vigorously until it becomes a milky white viscous solution, adjust the pH of the mixture to 7 with dilute hydrochloric acid, filter, wash, and freeze-dry to obtain cellulose microspheres.

[0009] Furthermore, the cellulose in step 1) has an average molecular weight of 1.01 × 10⁻⁶. 5 g / mol cotton pulp cellulose; and / or, polyethylene glycol is polyethylene glycol with an average molecular weight of 1000 g / mol; and / or, in step 1), the mass ratio of cellulose: sodium hydroxide: polyethylene glycol: deionized water is 8:6:10:76. And / or, in step 2), the emulsifier is polyoxyethylene 20 sorbitan monooleate; and / or, the mass ratio of paraffin oil: emulsifier: water is 30:0.8:69.2.

[0010] Furthermore, the mass ratio of cellulose microspheres in step (1) to tetrabutyl titanate in step (2) is 40:17. This translates to a mass ratio of TiO2 produced after the reaction of cellulose microspheres and tetrabutyl titanate being 10:1.

[0011] Further, in step (2), the molar ratio of tetrabutyl titanate: thioacetic acid: N,N-diisopropylethylamine is 100:2.2:8.8; and / or, the concentration of the glacial acetic acid solution is 98%, and the molar ratio of glacial acetic acid: tetrabutyl titanate is 4:1.

[0012] Furthermore, in step (3), the temperature of the solvothermal reaction is 160 °C and the time is 24 h.

[0013] This invention also provides a method for preparing the aforementioned supported S,N co-doped TiO2 visible light photocatalyst, wherein the catalyst is prepared according to the following method: (1) Disperse the cellulose microspheres evenly in anhydrous ethanol; (2) Take tetrabutyl titanate, thioacetic acid and N,N-diisopropylethylamine, and slowly add them to the dispersion under stirring. Then add glacial acetic acid solution dropwise to obtain a mixed solution. (3) Transfer the mixture into a sealed container and carry out a solvothermal reaction. After the reaction is completed, cool to room temperature, filter, wash, and dry to obtain the final product.

[0014] The present invention also provides the use of the aforementioned supported S,N co-doped TiO2 visible light catalyst for the degradation of dye wastewater.

[0015] This invention uses cellulose microspheres as a carrier and selects specific S and N raw materials to prepare a supported S,N co-doped TiO2 visible light catalyst. This catalyst exhibits good photocatalytic activity, is non-toxic to organisms, and has excellent stability under visible light irradiation. It has excellent degradation ability for dye wastewater, and the catalytic ability is particularly good when the S / N molar ratio is 1:4. It has particularly high degradation efficiency when applied to methyl red solution as a simulated dye wastewater.

[0016] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0017] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0018] Figure 1 The degradation efficiency of fuel wastewater by photocatalysis is shown in the figure. Detailed Implementation

[0019] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products. Among them, cellulose (Jiangsu Xianfeng Nanomaterials Technology), polyoxyethylene (20) sorbitan monostearate (Tween 60) (Jiangsu Haian Petrochemical Co., Ltd.), and paraffin oil (CNPC Karamay Petrochemical Co., Ltd.) are used. Example 1: Preparation of the supported S,N co-doped TiO2 visible light photocatalyst of the present invention 1. Preparation of cellulose microspheres 1) Take 120g sodium hydroxide, 200g polyethylene glycol and 1520g deionized water and mix them to prepare a mixed solution. Add 160g cellulose to the above mixed solution, cool to -20℃ and stir vigorously to obtain a transparent solution A. 2) Take 16g of Tween 60 and mix it with 1384g of deionized water. Then, emulsify 600g of paraffin oil and disperse it evenly in the aforementioned aqueous solution to obtain suspension B. 3) Slowly add solution A to suspension B, stir vigorously until it becomes a milky white viscous liquid, adjust the pH of the mixture to 7 with dilute hydrochloric acid, filter, wash, and freeze dry (freeze drying process: freeze continuously at liquid nitrogen [-196℃] for 1 hour to ensure complete freezing; then freeze dry at 0.03 mbar pressure and -50℃ for 48 hours using a freeze dryer) to obtain cellulose microspheres. 2. Preparation of the visible light photocatalyst of this invention (1) Disperse 400g of cellulose microspheres evenly in 80g of anhydrous ethanol to obtain a dispersion; (2) Take 170g tetrabutyl titanate (0.5mol), 0.85g thioacetic acid (0.011mol) and 5.74g N,N-diisopropylethylamine (0.044mol) (S / N is 1:4), and slowly add them to the dispersion under stirring. Then add 120g (2mol) of 98% glacial acetic acid solution dropwise to obtain a mixed solution. (3) The mixture was transferred into a stainless steel sealed container and subjected to a solvothermal reaction (160°C, 24 h). After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the S,N co-doped TiO2 catalyst supported on cellulose microspheres of the present invention.

[0020] Example 2: Preparation of the supported S,N co-doped TiO2 visible light photocatalyst of the present invention 1. Preparation of cellulose microspheres The preparation method of cellulose microspheres is the same as in Example 1.

[0021] 2. Preparation of the catalyst of this invention (1) Disperse 400g of cellulose microspheres evenly in 80g of anhydrous ethanol to obtain a dispersion; (2) Take 170g tetrabutyl titanate, 0.7g thioacetic acid and 5.91g N,N-diisopropylethylamine (S / N is 1:5), and slowly add them to the dispersion under stirring. Then add 120g of 98% glacial acetic acid solution dropwise to obtain a mixed solution. (3) The mixture was transferred into a stainless steel sealed container and subjected to a solvothermal reaction (160°C, 24 h). After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the S,N co-doped TiO2 catalyst supported on cellulose microspheres of the present invention.

[0022] Example 3: Preparation of the supported S,N co-doped TiO2 visible light photocatalyst of the present invention 1. Preparation of cellulose microspheres The preparation method of cellulose microspheres is the same as in Example 1.

[0023] 2. Preparation of the catalyst of this invention (1) Disperse 400g of cellulose microspheres evenly in 80g of anhydrous ethanol to obtain a dispersion; (2) Take 170g tetrabutyl titanate, 1.045g thioacetic acid and 5.32g N,N-diisopropylethylamine (S / N is 1:3), and slowly add them to the dispersion under stirring. Then add 120g of 98% glacial acetic acid solution dropwise to obtain a mixed solution. (3) The mixture was transferred into a stainless steel sealed container and subjected to a solvothermal reaction (160°C, 24 h). After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the S,N co-doped TiO2 catalyst supported on cellulose microspheres of the present invention.

[0024] The following experimental examples demonstrate the beneficial effects of the present invention: Experimental example: Verification of the effect of photocatalyst on the degradation of dye wastewater I. Material Preparation (I) Experimental Setup This experiment consisted of 7 experimental groups, and the catalysts used in the 7 experimental groups were: The sample in experimental group 1 was catalyst 1, which was a TiO2 catalyst supported on cellulose microspheres. The sample in experimental group 2 was catalyst 2, which was a cellulose microsphere-supported S-doped TiO2 catalyst. The sample in experimental group 3 was catalyst 4, which was a cellulose microsphere-supported N-doped TiO2 catalyst. The sample in experimental group 4 was catalyst 4, which was a cellulose microsphere supported S,N co-doped TiO2 catalyst (S / N ratio was 1:4). The sample in experimental group 5 was catalyst 4, which was recovered after degradation experiments (used 10 times). Catalyst 4 was a cellulose microsphere supported on S,N co-doped TiO2 catalyst (S / N ratio of 1:4). The sample in experimental group 6 was catalyst 5, which was a cellulose microsphere-supported S,N co-doped TiO2 catalyst (S / N ratio was 1:5). The sample in experimental group 7 was catalyst 6, which was a TiO2 catalyst supported on cellulose microspheres and co-doped with S and N (S / N ratio of 1:3).

[0025] (II) Material preparation process 1. Preparation of Catalyst 1 (1) 400g of cellulose microspheres (the preparation method of cellulose microspheres is the same as in Example 1) were uniformly dispersed in 80g of anhydrous ethanol to obtain a dispersion; (2) Take 170g of tetrabutyl titanate and slowly add it to the dispersion under stirring. Then add 120g of 98% glacial acetic acid solution dropwise to obtain a mixed solution. (3) Transfer the mixture into a stainless steel sealed container and carry out a solvothermal reaction (160℃, 24 h). After the reaction is completed, cool to room temperature, filter, wash, and dry to obtain the final product.

[0026] 2. Preparation of Catalyst 2 (1) 400g of cellulose microspheres (the preparation method of cellulose microspheres is the same as in Example 1) were uniformly dispersed in 80g of anhydrous ethanol to obtain a dispersion; (2) Take 170g tetrabutyl titanate and 4.22g thioacetic acid, and slowly add them to the dispersion while stirring. Then add 120g glacial acetic acid with a concentration of 98% dropwise to obtain a mixed solution. (3) Transfer the mixture into a stainless steel sealed container and carry out a solvothermal reaction (160℃, 24 h). After the reaction is completed, cool to room temperature, filter, wash, and dry to obtain the final product.

[0027] 3. Preparation of Catalyst 3 (1) 400g of cellulose microspheres (the preparation method of cellulose microspheres is the same as in Example 1) were uniformly dispersed in 80g of anhydrous ethanol to obtain a dispersion; (2) Take 170g of tetrabutyl titanate and 7.17g of N,N-diisopropylethylamine, and slowly add them to the dispersion under stirring. Then add 120g of 98% glacial acetic acid solution dropwise to obtain a mixed solution. (3) Transfer the mixture into a stainless steel sealed container and carry out a solvothermal reaction (160℃, 24 h). After the reaction is completed, cool to room temperature, filter, wash, and dry to obtain the final product.

[0028] 4. Preparation of Catalyst 4 Prepared according to the method of Example 1.

[0029] 5. Preparation of Catalyst 5 Prepared according to the method of Example 2.

[0030] 6. Preparation of Catalyst 6 Prepared according to the method of Example 3.

[0031] II. Experimental Methods Using a 10 mg / L methyl red solution as simulated dye wastewater, the photodegradation performance of different catalyst samples on methyl red solution was tested. 45 mg of photocatalyst and 300 mL of methyl red solution were weighed and added sequentially to a transparent glass beaker. The mixture was stirred in the dark for 30 min to allow the photocatalyst and methyl red solution to reach adsorption-desorption equilibrium. A 500 W xenon lamp was then used as the visible light source to irradiate the mixed solution. Samples were taken at 10 min, 20 min, 40 min, 60 min, 90 min, and 120 min after the start of the reaction. The samples were centrifuged (10,000 rpm, 5 min), and the supernatant was collected. The absorbance of the methyl red solution during the photocatalytic reaction was measured using a UV-1240 UV-Vis spectrophotometer (Shimadzu Corporation, Japan). The photocatalytic degradation rate T% of the methyl red solution was calculated according to the Lambert-Beer Law. In the formula, A0 and A t The absorbance values ​​of the methyl orange solution are shown at time t before and after the start of the photoreaction, respectively.

[0032] III. Experimental Results Experimental results are as follows Figure 1 As shown: The photocatalytic degradation rate diagram of the samples shows that the catalytic degradation rate of TiO2 catalyst supported on cellulose microspheres without S or N doping is very poor under visible light irradiation, with a degradation rate of only 8% after 120 min of irradiation. The catalytic degradation rate of TiO2 catalyst supported on cellulose microspheres with S or N doping alone is significantly improved under visible light irradiation, reaching 47% and 58% respectively after 120 min of irradiation.

[0033] The three S and N co-doped cellulose microspheres supported on TiO2 catalysts of this invention exhibit the highest degradation rates of 75%, 93%, and 71% respectively after 120 min of visible light irradiation. Compared with the S or N-doped cellulose microspheres supported on TiO2 catalysts with the same molar amount of doping, the catalytic effect is significantly improved.

[0034] Among the three supported S,N co-doped TiO2 catalysts of this invention, the catalyst with an S / N ratio of 1:4 (prepared in Example 1) showed the best performance, achieving a 95% degradation rate within 120 min under room temperature and natural light irradiation. This is significantly higher than the catalysts with an S / N ratio of 1:3 (prepared in Example 1) or 1:5 (prepared in Example 1), with an improvement of 18-21%. After 10 cycles of use, the degradation rate of the catalyst with an S / N ratio of 1:4 (prepared in Example 1) remained close to 90%.

[0035] In summary, the supported S,N co-doped TiO2 visible light photocatalyst of this invention exhibits excellent photocatalytic activity under visible light irradiation and demonstrates superior degradation ability for dye wastewater. It can be applied to the degradation of dye wastewater and has excellent application prospects.

Claims

1. A supported S,N co-doped TiO2 visible light photocatalyst for degrading dye wastewater, characterized in that, The catalyst is prepared by reacting tetrabutyl titanate, thioacetic acid, N,N-diisopropylethylamine and cellulose microspheres to obtain S,N co-doped TiO2 cellulose microspheres, wherein the total molar amount of S and N to the molar percentage of TiO2 is 11%, the molar ratio of S / N is 1:4, and the mass ratio of TiO2 to cellulose microspheres is 10:

100. The catalyst is prepared according to the following method: (1) Disperse the cellulose microspheres uniformly in anhydrous ethanol to obtain a dispersion; (2) Take tetrabutyl titanate, thioacetic acid and N,N-diisopropylethylamine, and slowly add them to the aforementioned dispersion while stirring. Then add glacial acetic acid solution dropwise to obtain a mixed solution. (3) Transfer the mixture into a sealed container and carry out a solvothermal reaction. After the reaction is completed, cool to room temperature, filter, wash, and dry to obtain the final product. The mass ratio of cellulose microspheres in step (1) to tetrabutyl titanate in step (2) is 400:170; In step (2), the molar ratio of tetrabutyl titanate: thioacetic acid: N,N-diisopropylethylamine is 100:2.2:8.8; and / or, the concentration of the glacial acetic acid solution is 98%, and the molar ratio of glacial acetic acid: tetrabutyl titanate is 4:1; The cellulose microspheres were prepared according to the following method: 1) Add cellulose to a mixed solution of sodium hydroxide, polyethylene glycol and deionized water, cool to -20°C, and stir vigorously until a transparent solution A is obtained; 2) Emulsify and disperse the paraffin oil in a deionized aqueous solution containing an emulsifier to obtain suspension B; 3) Slowly add solution A to suspension B, stir vigorously until it becomes a milky white viscous solution, adjust the pH of the mixture to 7 with dilute hydrochloric acid, filter, wash, and freeze-dry to obtain cellulose microspheres; The cellulose in step 1) has an average molecular weight of 1.01 × 10⁻⁶. 5 g / mol cotton pulp cellulose; and / or, polyethylene glycol is polyethylene glycol with an average molecular weight of 1000 g / mol; In step 1), the mass ratio of cellulose: sodium hydroxide: polyethylene glycol: deionized water is 8:6:10:76; In step 2), the emulsifier is polyoxyethylene 20 sorbitan monooleate; and / or, the mass ratio of paraffin oil: emulsifier: water is 30:0.8:69.2; In step (3), the temperature of the solvothermal reaction is 160 °C and the time is 24 h.

2. A method for preparing the supported S,N co-doped TiO2 visible light photocatalyst of claim 1, characterized in that, The catalyst is prepared according to the following method: (1) Disperse the cellulose microspheres evenly in anhydrous ethanol; (2) Take tetrabutyl titanate, thioacetic acid and N,N-diisopropylethylamine, and slowly add them to the dispersion under stirring. Then add glacial acetic acid solution dropwise to obtain a mixed solution. (3) Transfer the mixture into a sealed container and carry out a solvothermal reaction. After the reaction is completed, cool to room temperature, filter, wash, and dry to obtain the final product.

3. The use of the supported S,N co-doped TiO2 visible light catalyst according to claim 1 for the degradation of dye wastewater.

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