Preparation method of visible light response water dispersible titanium dioxide nanomaterial
By preparing chlorine-doped visible light-responsive water-dispersible titanium dioxide nanomaterials, the problems of ultraviolet light response limitation and aqueous phase aggregation of titanium dioxide photocatalysts have been solved, achieving efficient and stable photocatalytic performance and dispersibility, suitable for wastewater treatment and air pollution control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NAT NANOTECHNOLOGY STAR(SHANGHAI) DEV CO LTD
- Filing Date
- 2023-07-06
- Publication Date
- 2026-06-02
Smart Images
Figure CN116812973B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalysis technology, specifically relating to a method for preparing visible light-responsive water-dispersible titanium dioxide nanomaterials for photocatalysis. Background Technology
[0002] Titanium dioxide, as a promising photocatalyst, possesses excellent chemical stability, high light transmittance and refractive index, is non-toxic and harmless, abundant in source, and low in cost, and has been widely used in wastewater treatment, air pollution control, and other fields. However, due to its wide band gap, it can only respond to short-wavelength, high-energy ultraviolet light, which accounts for only 4-6% of sunlight, greatly limiting its industrial application. Improving the utilization efficiency of titanium dioxide photocatalysts for sunlight and extending the absorption spectrum into the visible light region has always been a research hotspot. By doping titanium dioxide crystals with other elements, introducing impurity and defect energy levels into the band gap, the energy required for electron excitation can be reduced, thus extending the spectral response range of titanium dioxide photocatalysts into the visible light region. Early studies focused on metal ion doping, but the introduction of metal ions easily forms carrier recombination centers, reducing photocatalytic efficiency, and the catalyst stability is not high. Later research focused on non-metallic atom doping, finding that nitrogen, carbon, sulfur, iodine, and other non-metallic doped titanium dioxide all exhibit varying degrees of visible light response activity.
[0003] Titanium dioxide, as a photocatalyst, often needs to be dispersed in an aqueous system in practical applications such as wastewater treatment and air pollution control. However, because titanium dioxide is insoluble in water and has a significantly higher density than water, it easily aggregates and forms precipitates in the aqueous phase, making it difficult to effectively exert its photocatalytic effect. Improving the hydrophilicity of titanium dioxide by modifying its surface can enhance its water dispersibility to some extent. Patent CN101723445A uses tetrabutyl titanate as the titanium source and concentrated hydrochloric acid as the solvent, introducing polyethylene glycol during alcoholysis. After crystallization under hydrothermal conditions, the surface is coated with polyethylene glycol, resulting in better water dispersibility. However, the reaction process requires the use of hazardous concentrated hydrochloric acid, which is not very safe or environmentally friendly. Patent CN103980738A uses a precipitation method to obtain nano-titanium dioxide precursors, which are then transferred to a high-pressure reactor for hydrothermal reaction to obtain nano-titanium dioxide mother liquor. Water-soluble acrylate monomers and initiators are then added to polymerize on the titanium dioxide surface, resulting in polyacrylate-coated modified nano-titanium dioxide powder. This method involves multiple steps, is complex to operate, and is difficult to scale up for production. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing visible light responsive water-dispersible titanium dioxide nanomaterials.
[0005] The objective of this invention is achieved through the following scheme: a method for preparing visible light-responsive water-dispersible titanium dioxide nanomaterials, using alkoxy-based titanates as the titanium source, low-carbon diols as the solvent, and sodium hypochlorite as the oxidant, and employing an in-situ oxidation method under solvothermal conditions to prepare chlorine-doped visible light-responsive water-dispersible titanium dioxide nanomaterials, comprising the following steps:
[0006] (1) Precursor formulation
[0007] A certain volume of alkoxy titanate was added dropwise to a certain volume of low-carbon diol, and stirred at 30–40 °C for 1–2 h. After the mixture was homogeneous and no white precipitate was formed, a certain mass of sodium hypochlorite was added, and stirring was continued for 1–2 h to obtain a transparent pale yellow solution.
[0008] (2) Solvent thermal reaction
[0009] The transparent pale yellow solution obtained in step (1) was transferred to a polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 65-80%. The reactor was placed in an oven and reacted at 140-180 °C for 14-18 h. After the reaction was completed, the reactor was cooled to room temperature.
[0010] (3) Reactant treatment
[0011] The reaction product obtained in step (2) was washed three times with water and ethanol, and centrifuged at 10,000 rpm to obtain wet nano-titanium dioxide powder. The wet powder was then dried in an oven at 60–80 °C for 10–12 h to obtain dry powder. The dry powder was then ground into a fine powder using an agate mortar and pestle to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.
[0012] The alkoxy titanate is one of n-butyl titanate and tetraisopropyl titanate.
[0013] The low-carbon diol is one of ethylene glycol, 1,3-propanediol, and 1,4-butanediol.
[0014] The volume ratio of the alkoxy titanate to the low-carbon diol is 2.5–5.0:100.0.
[0015] The molar ratio of sodium hypochlorite to alkoxy titanate is 0.5–1.0:1.0.
[0016] The method for preparing the visible-light-responsive water-dispersible titanium dioxide nanomaterial involves, under solvothermal conditions, utilizing the reducing properties of low-carbon diols during the alcoholysis of alkoxy-based titanates. Sodium hypochlorite is used to oxidize the hydroxyl groups of the alcohol to aldehydes, which are further oxidized to carboxyl groups. These carboxyl groups are adsorbed onto the surface of newly generated titanium dioxide nanoparticles, imparting excellent water dispersibility to the material. Simultaneously, the oxidation product, chloride ions, enter the titanium dioxide lattice to form chloride-doped titanium dioxide nanomaterials, extending the absorption spectrum of titanium dioxide into the visible light region and improving the utilization efficiency of sunlight.
[0017] Compared with the prior art, the advantages of the present invention are:
[0018] The preparation method of this invention is simple and easy to implement, with few steps, and is suitable for industrial scale-up. It does not use strong acids, making it safe and environmentally friendly.
[0019] The preparation method of this invention can produce excellent water-dispersible titanium dioxide nanomaterials with visible light response in one step, which improves the utilization efficiency of titanium dioxide for sunlight. At the same time, it is convenient to prepare water-based diluent products for subsequent applications such as wastewater treatment and air pollution control, and can exert catalytic performance continuously, stably and efficiently under sunlight irradiation. Attached Figure Description
[0020] Figure 1 Comparison of UV-Vis diffuse reflectance spectra of commercial titanium dioxide P25 (Evonik Industries) and visible light responsive water-dispersible titanium dioxide nanomaterials prepared in Example 1. Detailed Implementation
[0021] The technical solution of the present invention will be further described below with reference to specific embodiments. The scope of protection of the present invention is not limited to the following embodiments; these examples are provided for illustrative purposes only and do not limit the present invention in any way.
[0022] Example 1
[0023] A visible light-responsive, water-dispersible titanium dioxide nanomaterial is prepared using alkoxy-based titanate as the titanium source, low-carbon diol as the solvent, and sodium hypochlorite as the oxidant via in-situ oxidation under solvothermal conditions, following these steps:
[0024] (1) Precursor formulation
[0025] 0.325 ml of tetraisopropyl titanate was added dropwise to 13 ml of ethylene glycol and stirred at 40°C for 1 h. After the mixture was homogeneous and no white precipitate was formed, 0.082 g of sodium hypochlorite was added and the mixture was stirred for another 1 h to obtain a transparent pale yellow solution.
[0026] (2) Solvent thermal reaction
[0027] The transparent pale yellow solution obtained in step (1) was transferred to a 20 ml polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 67%. The reactor was placed in an oven and reacted at 180 °C for 14 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product.
[0028] (3) Reactant treatment
[0029] The reaction product obtained in step (2) was washed three times with water and ethanol respectively, and centrifuged at 10,000 rpm to obtain nano-titanium dioxide wet powder. The wet powder was placed in an oven and dried at 80°C for 10 h to obtain dry powder. The dry powder was finely ground with an agate mortar to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.
[0030] In this embodiment, the volume ratio of tetraisopropyl titanate to ethylene glycol is 2.5:100.0, and the molar ratio of sodium hypochlorite to tetraisopropyl titanate is 1.0:1.0. Example 2
[0031] A visible light-responsive, water-dispersible titanium dioxide nanomaterial, similar to that in Example 1, was prepared according to the following steps:
[0032] (1) Precursor formulation
[0033] 0.5 ml of tetraisopropyl titanate was added dropwise to 14 ml of 1,3-propanediol and stirred at 30°C for 2 h. After the mixture was homogeneous and no white precipitate was formed, 0.063 g of sodium hypochlorite was added and the mixture was stirred for another 2 h to obtain a transparent pale yellow solution.
[0034] (2) Solvent thermal reaction
[0035] The transparent pale yellow solution obtained in step (1) was transferred to a 20 ml polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 73%. The reactor was placed in an oven and reacted at 140°C for 18 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product.
[0036] (3) Reactant treatment
[0037] The reaction product obtained in step (2) was washed three times with water and ethanol respectively, and centrifuged at 10,000 rpm to obtain nano-titanium dioxide wet powder. The wet powder was placed in an oven and dried at 60°C for 12 h to obtain dry powder. The dry powder was finely ground with an agate mortar to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.
[0038] In this embodiment, the volume ratio of tetraisopropyl titanate to 1,3-propanediol is 3.6:100.0, and the molar ratio of sodium hypochlorite to tetraisopropyl titanate is 0.5:1.0. Example 3
[0039] A visible light-responsive, water-dispersible titanium dioxide nanomaterial, similar to that in Example 1, was prepared according to the following steps:
[0040] (1) Precursor formulation
[0041] 0.76 ml of tetraisopropyl titanate was added dropwise to 15.2 ml of 1,4-butanediol and stirred at 35°C for 1.5 h until the mixture was homogeneous and no white precipitate was formed. Then, 0.134 g of sodium hypochlorite was added and the mixture was stirred for another 1.5 h to obtain a transparent pale yellow solution.
[0042] (2) Solvent thermal reaction
[0043] The transparent pale yellow solution obtained in step (1) was transferred to a 20 ml polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 80%. The reactor was placed in an oven and reacted at 160 °C for 18 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product.
[0044] (3) Reactant treatment
[0045] The reaction product obtained in step (2) was washed three times with water and ethanol respectively, and centrifuged at 10,000 rpm to obtain nano-titanium dioxide wet powder. The wet powder was placed in an oven and dried at 70°C for 12 h to obtain dry powder. The dry powder was finely ground with an agate mortar to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.
[0046] In this embodiment, the volume ratio of tetraisopropyl titanate to 1,4-butanediol is 5.0:100.0, and the molar ratio of sodium hypochlorite to tetraisopropyl titanate is 0.7:1.0. Example 4
[0047] A visible light-responsive, water-dispersible titanium dioxide nanomaterial, similar to that in Example 1, was prepared according to the following steps:
[0048] (1) Precursor formulation
[0049] 0.5 ml of tetrabutyl titanate was added dropwise to 14.5 ml of 1,3-propanediol and stirred at 35°C for 1.5 h. After the mixture was homogeneous and no white precipitate was formed, 0.073 g of sodium hypochlorite was added and stirring was continued for 1.5 h to obtain a transparent pale yellow solution.
[0050] (2) Solvent thermal reaction
[0051] The transparent pale yellow solution obtained in step (1) was transferred to a 20 ml polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 75%. The reactor was placed in an oven and reacted at 160°C for 18 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product.
[0052] (3) Reactant treatment
[0053] The reaction product obtained in step (2) was washed three times with water and ethanol respectively, and centrifuged at 10,000 rpm to obtain nano-titanium dioxide wet powder. The wet powder was placed in an oven and dried at 70°C for 12 h to obtain dry powder. The dry powder was finely ground with an agate mortar to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.
[0054] In this embodiment, the volume ratio of tetrabutyl titanate to 1,3-propanediol is 3.4:100.0, and the molar ratio of sodium hypochlorite to tetrabutyl titanate is 0.7:1.0.
[0055] Those skilled in the art should note that the embodiments described in this invention are merely exemplary, and various other substitutions, changes, and improvements can be made within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is defined only by the claims.
Claims
1. A method for preparing a visible light responsive water dispersible titanium dioxide nanomaterial, characterized in that, Chlorine-doped, visible-light-responsive, water-dispersible titanium dioxide nanomaterials were prepared by in-situ oxidation under solvothermal conditions using alkoxy-based titanates as the titanium source, low-carbon diols as the solvent, and sodium hypochlorite as the oxidant. The process included the following steps: (1) Precursor formulation An alkoxy titanate was added dropwise to a low-carbon diol, wherein the volume ratio of the alkoxy titanate to the low-carbon diol was 2.5–5.0:100.0; the mixture was stirred at 30–40°C for 1–2 hours until it was homogeneous and free of white precipitate; then sodium hypochlorite was added, wherein the molar ratio of sodium hypochlorite to the alkoxy titanate was 0.5–1.0:1.0; the mixture was stirred for another 1–2 hours to obtain a transparent pale yellow solution. (2) Solvent thermal reaction The transparent pale yellow solution obtained in step (1) was transferred to a polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 65-80%. The reactor was placed in an oven and reacted at 140-180℃ for 14-18 hours. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product. (3) Reactant treatment The reaction product obtained in step (2) was washed three times with water and ethanol, respectively, and centrifuged at 10,000 rpm to obtain wet titanium dioxide nanoparticles. The wet powder was placed in an oven and dried at 60-80℃ for 10-12 h to obtain dry powder. The dry powder was then ground into a fine powder using an agate mortar and pestle to obtain visible light responsive water-dispersible titanium dioxide nanomaterials. The low-carbon diol is one of ethylene glycol, 1,3-propanediol, and 1,4-butanediol.
2. The method for preparing a visible light-responsive water-dispersible titanium dioxide nanomaterial according to claim 1, characterized in that, The alkoxy titanate is one of n-butyl titanate and tetraisopropyl titanate.
3. The method for preparing a visible light-responsive water-dispersible titanium dioxide nanomaterial according to any one of claims 1 to 2, characterized in that, Prepare according to the following steps: (1) Precursor formulation 0.325 ml of tetraisopropyl titanate was added dropwise to 13 ml of ethylene glycol, i.e., the volume ratio of tetraisopropyl titanate to ethylene glycol was 2.5:100.
0. The mixture was stirred at 40°C for 1 h until it was homogeneous and no white precipitate was formed. Then sodium hypochlorite was added, with a molar ratio of sodium hypochlorite to tetraisopropyl titanate of 1.0:1.
0. The mixture was stirred for another 1 h to obtain a transparent pale yellow solution. (2) Solvent thermal reaction The transparent pale yellow solution obtained in step (1) was transferred to a 20 ml polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 67%. The reactor was placed in an oven and reacted at 180°C for 14 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product. (3) Reactant treatment The reaction product obtained in step (2) was washed three times with water and ethanol respectively, and centrifuged at 10,000 rpm to obtain nano-titanium dioxide wet powder. The wet powder was placed in an oven and dried at 80°C for 10 h to obtain dry powder. The dry powder was finely ground with an agate mortar to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.
4. A method for preparing a visible light-responsive water-dispersible titanium dioxide nanomaterial according to any one of claims 1 to 2, characterized in that, Prepare according to the following steps: (1) Precursor formulation 0.5 ml of tetraisopropyl titanate was added dropwise to 14 ml of 1,3-propanediol, making the volume ratio of tetraisopropyl titanate to 1,3-propanediol 3.6:100.
0. The mixture was stirred at 30°C for 2 h until it was homogeneous and no white precipitate was formed. Then sodium hypochlorite was added, with a molar ratio of sodium hypochlorite to tetraisopropyl titanate of 0.5:1.
0. The mixture was stirred for another 2 h to obtain a transparent pale yellow solution. (2) Solvent thermal reaction The transparent pale yellow solution obtained in step (1) was transferred to a 20 ml polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 73%. The reactor was placed in an oven and reacted at 140°C for 18 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product. (3) Reactant treatment The reaction product obtained in step (2) was washed three times with water and ethanol respectively, and centrifuged at 10,000 rpm to obtain nano-titanium dioxide wet powder. The wet powder was placed in an oven and dried at 60°C for 12 h to obtain dry powder. The dry powder was finely ground with an agate mortar to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.
5. A method for preparing a visible light-responsive, water-dispersible titanium dioxide nanomaterial according to any one of claims 1 to 2, characterized in that, Prepare according to the following steps: (1) Precursor formulation 0.76 ml of tetraisopropyl titanate was added dropwise to 15.2 ml of 1,4-butanediol, with a volume ratio of tetraisopropyl titanate to 1,4-butanediol of 5.0:100.
0. The mixture was stirred at 35°C for 1.5 h until it was homogeneous and free of white precipitate. Then, sodium hypochlorite was added, with a molar ratio of sodium hypochlorite to tetraisopropyl titanate of 0.7:1.
0. The mixture was stirred for another 1.5 h to obtain a transparent pale yellow solution. (2) Solvent thermal reaction The transparent pale yellow solution obtained in step (1) was transferred to a 20 ml polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 80%. The reactor was placed in an oven and reacted at 160°C for 18 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product. (3) Reactant treatment The reaction product obtained in step (2) was washed three times with water and ethanol respectively, and centrifuged at 10,000 rpm to obtain nano-titanium dioxide wet powder. The wet powder was placed in an oven and dried at 70°C for 12 h to obtain dry powder. The dry powder was finely ground with an agate mortar to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.
6. A method for preparing a visible light-responsive water-dispersible titanium dioxide nanomaterial according to any one of claims 1 to 2, characterized in that, Prepare according to the following steps: (1) Precursor formulation 0.5 ml of tetrabutyl titanate was added dropwise to 14.5 ml of 1,3-propanediol, with a volume ratio of tetrabutyl titanate to 1,3-propanediol of 3.4:100.
0. The mixture was stirred at 35°C for 1.5 h until it was homogeneous and free of white precipitate. Then, sodium hypochlorite was added, with a molar ratio of sodium hypochlorite to tetrabutyl titanate of 0.7:1.
0. The mixture was stirred for another 1.5 h to obtain a transparent pale yellow solution. (2) Solvent thermal reaction The transparent pale yellow solution obtained in step (1) was transferred to a 20 ml polytetrafluoroethylene-lined stainless steel high-pressure reactor with a filling degree of 75%. The reactor was placed in an oven and reacted at 160°C for 18 h. After the reaction was completed, the reactor was cooled to room temperature to obtain the reaction product. (3) Reactant treatment The reaction product obtained in step (2) was washed three times with water and ethanol respectively, and centrifuged at 10,000 rpm to obtain nano-titanium dioxide wet powder. The wet powder was placed in an oven and dried at 70°C for 12 h to obtain dry powder. The dry powder was finely ground with an agate mortar to obtain visible light responsive water-dispersible titanium dioxide nanomaterials.