Preparation method of TiO2 powder with rutile and anatase core-shell structure

Abstract

The invention discloses a preparation method of TiO2 powder with a rutile and anatase core-shell structure, and particularly relates to the technical field of photocatalytic material preparation. According to the method, rutile phase TiO2 powder is used as a core material, a titanate intermediate layer is formed on the surface of a particle through an accurately controlled hydrothermal alkali treatment process, and then a surface layer phase is converted into an anatase phase through acid pickling treatment and controllable heat treatment, so that a complete core-shell heterojunction structure is constructed. The process flow is relatively simple, the cost is controllable, the phase structure conversion rate is high, and the shell thickness can be accurately regulated and controlled. The obtained TiO2 core-shell structure powder has excellent structural stability of a rutile phase and high surface reaction activity of an anatase phase, and shows remarkably enhanced photocatalytic degradation performance under the condition of ultraviolet irradiation, and the catalytic efficiency of the TiO2 core-shell structure powder is greatly improved compared with that of single rutile phase TiO2; and a new process method is provided for large-scale preparation of efficient photocatalytic materials.

Description

Technical Field

[0001] This application relates to a method for preparing TiO2 powder with a rutile@anatase core-shell structure, belonging to the field of photocatalytic material preparation technology. Background Technology

[0002] TiO2, as a high-performance multifunctional inorganic material, is widely used in various fields such as photocatalytic degradation of pollutants, photoelectric conversion, antibacterial and anti-corrosion, and solar energy utilization due to its strong chemical stability, non-toxicity, and low cost. The performance of TiO2 is closely related to its crystal structure, among which rutile and anatase are the two most common and valuable crystal forms. The two exhibit significant differences in physicochemical properties: Rutile TiO2 has excellent thermal stability, mechanical strength, and electron transport efficiency, and its dense crystal structure can ensure the structural integrity of the material under complex working conditions (such as high-temperature reactions and long-term use) when used as a powder core. However, it has few surface active sites and a low specific surface area, resulting in relatively limited photocatalytic activity and surface reactivity. Anatase TiO2, on the other hand, has a higher specific surface area, abundant surface defects, and excellent photocatalytic activity. Its surface adsorption capacity and reactivity are outstanding, but its thermal stability is poor, and it is prone to crystal transformation under high-temperature environments. It also has weak mechanical properties, making it difficult to balance structural stability and application performance when used alone as a functional powder.

[0003] In practical applications, single-crystal TiO2 powders often fail to meet the comprehensive performance requirements of complex scenarios. For example, in photocatalytic reactions, materials need both a stable structure to ensure recycling efficiency and high surface activity to enhance the catalytic reaction rate. In optoelectronic materials, the core structure requires efficient electron transport capabilities, while the surface provides sufficient reaction sites to promote interfacial charge transfer. Traditional single-crystal TiO2 powders or simple physical mixtures of bicrystalline powders struggle to achieve the synergistic benefits of both crystal forms—the two crystal forms lack tight bonding in physical mixtures, hindering electron transport and easily leading to component separation, thus failing to achieve a performance improvement effect greater than the sum of its parts (1+1>2). Therefore, constructing core-shell structure TiO2 powders with a rutile core and anatase shell, achieving synergistic performance through the functional complementarity of the core and shell layers, has become a key direction for overcoming the limitations of single-crystal TiO2 powders.

[0004] Currently, there are two major technical challenges in the preparation of core-shell TiO2 powder: First, some methods use physical coating or chemical deposition to construct the shell, which can easily lead to uneven distribution of the anatase shell thickness and weak bonding with the rutile core interface. This can cause the shell to detach during subsequent applications, seriously affecting the stability of the material. Second, some chemical conversion methods rely on expensive template agents, special catalysts, or harsh reaction conditions such as high temperature and high pressure. This not only increases the complexity of the process and production costs, but also makes it difficult to accurately control the crystal purity of the surface anatase and to achieve precise control over the thickness of the anatase shell and the heterojunction interface layer.

[0005] To address the aforementioned technical problems, the inventors employed a mild, directional chemical transformation process to achieve in-situ uniform growth of the anatase shell on the rutile core surface. This not only ensures a tightly bonded heterojunction interface between the anatase shell and the rutile core, fundamentally solving the problems of uneven shell formation and easy detachment, but also allows for precise control of the thickness of the anatase shell and the heterojunction interface layer through process parameter adjustment, while simultaneously guaranteeing the high crystal purity of the anatase phase. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing TiO2 powder with a rutile@anatase core-shell structure. This method achieves uniform and continuous coating of the anatase phase on the surface of rutile TiO2 particles by precisely controlling the parameters of hydrothermal alkaline treatment, acid washing conversion, and heat treatment. This results in a heterojunction structure with high lattice matching and tight interfacial bonding, effectively solving the technical problems of numerous phase interface defects, poor structural stability, and low precision in controlling the shell thickness and heterojunction interface layer thickness in traditional preparation methods. This provides a reliable technical solution for the large-scale application of high-performance photocatalytic materials.

[0007] To achieve the above objectives, this application adopts the following technical solution: This application provides a method for preparing TiO2 powder with a rutile@anatase core-shell structure, the method comprising the following steps: S1: Alkali treatment process Rutile TiO2 powder was mixed evenly with an alkaline solution and placed in a high-pressure reactor for hydrothermal reaction under constant temperature and stirring conditions. After the reaction was completed, solid-liquid separation was performed, and the product was repeatedly washed with deionized water until the washing solution was neutral. After drying, the alkaline-treated product was obtained. S2: Acid treatment process The alkaline-treated product obtained in step S1 is dispersed in an acidic solution and subjected to acid treatment under constant temperature and stirring conditions. After the acid treatment is completed, solid-liquid separation is performed, and the product is repeatedly washed with deionized water until the washing solution is neutral. After drying, the acid-treated product is obtained. S3: Heat treatment process The acid-treated product obtained in step S2 is spread evenly in a crucible and calcined. After calcination, it is naturally cooled to room temperature in the furnace to obtain TiO2 powder with a rutile@anatase core-shell structure.

[0008] Further, in step S1, the alkaline solution consists of an alkaline substance and water, and the mass ratio of the rutile TiO2 powder, the alkaline substance, and water is 1:(5-25):(15-100); rutile TiO2 powder D 50 The range is 100-500,000 nm; The alkaline solution is prepared from at least one of sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and cesium hydroxide (CsOH), preferably NaOH; The reactor and liner used for the hydrothermal reaction are commercially available reactors and liners, which can be stainless steel reactors, nickel-based alloy reactors, or carbon manganese steel reactors. The reactor liner can be a polytetrafluoroethylene (PTFE) liner or a modified polytetrafluoroethylene (PPL / TFM) liner, preferably a stainless steel reactor and a polytetrafluoroethylene (PTFE) liner. The hydrothermal reaction is carried out at a temperature of 80-200℃ for 2-200 hours, with a stirring speed of 10-1000 r / min. The material of the vacuum filtration membrane is selected from one or more of mixed cellulose ester (MCE), polyethersulfone (PES), nylon, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polycarbonate track etched (PCTE / PETE), preferably a PES membrane, with a pore size of ≤0.3 μm. The drying temperature is 30-200℃, the heating rate is 1-20℃ / min, and the holding time is 0.5-24 hours.

[0009] Further, in step S2, the acidic solution is an aqueous solution of an inorganic acid, wherein the inorganic acid is selected from any one or more combinations of hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), and perchloric acid (HClO4), preferably HCl or HNO3; The concentration of the acidic solution is 0.1-20 mol / L; The ratio of the alkaline-treated product to the acidic solution is ≥30mL of acidic solution per gram of alkaline-treated product, preferably a solid-liquid ratio of 1g:(30-120)mL; The acid treatment is performed at a temperature of 20-95℃ for a duration of 0.1-24 hours. The stirring speed for acid treatment is 10-1000 r / min; The material of the vacuum filtration membrane is selected from one or more of mixed cellulose ester (MCE), polyethersulfone (PES), nylon, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polycarbonate track etched (PCTE / PETE), preferably a PES membrane, with a pore size of ≤0.3 μm. The drying temperature is 30-200℃, the heating rate is 1-20℃ / min, and the holding time is 0.5-24 hours.

[0010] Furthermore, in step S3, the crucible is made of an inert material that can be calcined in an air atmosphere, selected from any one of corundum crucible, silicon carbide crucible, quartz crucible, and boron nitride crucible, preferably a corundum crucible; In the calcination process, the powder layer thickness is ≤1mm, the calcination temperature is 200-950℃, the heating rate is 1-20℃ / min, preferably 5℃ / min; the holding time is 5-500 min; and the calcination atmosphere is air.

[0011] This application also provides TiO2 powder with a rutile@anatase core-shell structure prepared by the above preparation method, wherein the D of the core-shell structured TiO2 powder is... 50 The range is 100-500,000 nm; The core phase of the core-shell structured TiO2 powder is rutile TiO2, and the shell phase is anatase TiO2. The thickness of the anatase phase layer is 1-1000 nm, and the thickness variation coefficient CV ≤ 15%. The thickness of the heterojunction interface layer formed between the core phase and the shell phase is 1-500 nm, and the thickness variation coefficient CV ≤ 10%. The specific surface area of ​​the core-shell structured TiO2 powder is 1-80 m². 2 / g.

[0012] This application also provides the application of TiO2 powder with a rutile@anatase core-shell structure prepared by the above preparation method in water treatment.

[0013] This application also provides the application of TiO2 powder with a rutile@anatase core-shell structure prepared by the above preparation method in the photocatalytic degradation of organic pollutants.

[0014] The core-shell structured TiO2 powder exhibits a photocatalytic degradation rate of ≥80% for organic pollutants in water under ultraviolet light irradiation.

[0015] The organic pollutants mentioned include those listed in the Shanghai Key Controlled New Pollutants List (2023 Edition): Perfluorooctyl sulfonic acid and its salts and perfluorooctyl sulfonyl fluoride (PFOS class); Perfluorooctanoic acid and its salts and related compounds (PFOA class); Decabromodiphenyl ether; Short-chain chlorinated paraffins; Hexachlorobutadiene; Pentachlorophenol and its salts and esters; Trichlorfon; Perfluorohexyl sulfonic acid and its salts and related compounds (PFHxS class); Declone and its cis and trans isomers; Dichloromethane; chloroform; Nonylphenol; Antibiotics (antibacterial drugs); New pollutants that have been phased out (such as anticides and cypermethrin); Microplastics; Bisphenol A.

[0016] The preparation method provided in this application transforms the surface layer of rutile powder particles into anatase phase, which is the core step in constructing a core-shell structure. Its necessity and significance are mainly reflected in the following three aspects: First, the core rutile phase can maintain the structural stability, mechanical strength, and electron transport efficiency of the powder, avoiding the thermal instability and mechanical defects of the anatase phase when used alone, and ensuring that the powder is not easily broken or degraded in crystal form during preparation and application. Second, the surface anatase phase can provide abundant surface active sites and high specific surface area, significantly improving the core application performance of the powder, such as photocatalysis, adsorption, and reaction activity, and making up for the shortcomings of insufficient surface activity of the rutile phase. Third, in the core-shell structure, a tight crystal interface is formed between the rutile core and the anatase shell, which can promote charge transfer and energy transfer between the two, realizing the synergistic effect of the two crystal forms, and its comprehensive performance far exceeds that of a single crystal form or a physical mixture system.

[0017] Compared with the prior art, this application has the following beneficial effects: 1) This application achieves dual uniformity at the particle scale in terms of the thickness of the anatase shell and the thickness of the rutile / anatase interface layer by constructing highly uniform reaction conditions; in the resulting core-shell structure, the anatase shell is uniformly distributed without local overthickness or absence, and the width of the phase interface transition region is consistent and continuous, effectively overcoming the structural defects such as uneven shell, blurred interface or loose bonding in traditional methods.

[0018] 2) Thanks to the coordinated and uniform control of the shell thickness and the interface layer thickness, the core-shell structure of the material obtained in this application has a tight and high-purity crystal phase interface, which significantly improves the charge separation efficiency and long-term stability of the material; the uniform anatase shell provides stable surface activity, while the uniform phase interface promotes the efficient transport of photogenerated charge carriers, and the two work together to enhance photocatalytic performance; at the same time, the core and shell are firmly bonded and are not easy to fall off or deteriorate under complex working conditions.

[0019] 3) This application does not require the use of template agents or harsh reaction conditions. It can achieve precise control of the thickness of the anatase phase shell and the phase interface layer simultaneously by optimizing the homogeneity of the reaction system. The process is simple, low-cost, and highly reproducible. It is suitable for the large-scale preparation of high-performance "rutile@anatase" core-shell TiO2 powder and has good industrialization prospects. Attached Figure Description

[0020] Figure 1 : Schematic diagram of the core-shell structure of TiO2. Detailed Implementation

[0021] To make the technical solution of this application clearer and easier to understand, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0022] This application provides a method for preparing TiO2 powder with a rutile@anatase core-shell structure, comprising the following steps: S1: Alkali treatment process Rutile TiO2 powder was mixed evenly with an alkaline solution and placed in a high-pressure reactor for hydrothermal reaction under constant temperature and stirring conditions. After the reaction was completed, solid-liquid separation was performed, and the product was repeatedly washed with deionized water until the washing solution was neutral. After drying, the alkaline-treated product was obtained. S2: Acid treatment process The alkaline-treated product obtained in step S1 is dispersed in an acidic solution and subjected to acid treatment under constant temperature and stirring conditions. After the acid treatment is completed, solid-liquid separation is performed, and the product is repeatedly washed with deionized water until the washing solution is neutral. After drying, the acid-treated product is obtained. S3: Heat treatment process The acid-treated product obtained in step S2 is spread evenly in a crucible and calcined. After calcination, it is naturally cooled to room temperature in the furnace to obtain TiO2 powder with a rutile@anatase core-shell structure.

[0023] The following description, in conjunction with specific embodiments, illustrates this point.

[0024] Unless otherwise specified, the experimental or testing methods described in the following examples are conventional methods; the reagents and materials described are obtained from conventional commercial sources unless otherwise specified.

[0025] Example 1 A method for preparing TiO2 powder with a rutile@anatase core-shell structure includes the following steps: S1 Alkali Treatment: Rutile TiO2 powder and sodium hydroxide solution are mixed evenly and placed in a high-pressure reactor for hydrothermal reaction under constant temperature and stirring conditions. After the reaction is completed, solid-liquid separation is performed by vacuum filtration. During the vacuum filtration process, the filtrate is repeatedly washed with deionized water until it is neutral. After drying, the alkali-treated product is obtained. S2 Acid Treatment: The alkaline-treated product obtained in step S1 is dispersed in hydrochloric acid solution and acid-treated under constant temperature and stirring conditions; after acid treatment, solid-liquid separation is performed by vacuum filtration. During vacuum filtration, the product is repeatedly washed with deionized water until the filtrate is neutral and then dried to obtain the acid-treated product. S3 Heat treatment: The acid-treated product obtained in step S2 is spread evenly in a crucible and calcined; after calcination, it is cooled to room temperature to obtain the core-shell structured TiO2 powder.

[0026] In step S1, the rutile TiO2 powder is mixed evenly with the alkaline solution, and the mass ratio of rutile TiO2 powder, alkaline substance, and water is 1:15:20; rutile TiO2 powder D 50 The wavelength was 2341 nm; the sodium hydroxide solid used was of analytical grade. The reactor and lining used for the hydrothermal reaction are stainless steel reactors and polytetrafluoroethylene (PTFE) linings; The hydrothermal reaction temperature is 140℃, and the hydrothermal reaction time is 20 hours; the stirring speed during the hydrothermal reaction is 100 r / min. The filter membrane used for filtration in step S1 is a polyethersulfone (PES) filter membrane with a pore size of 0.03 μm. In step S1, the drying temperature is 60°C, the heating rate is 3°C / min, and the holding time is 12 hours.

[0027] The concentration of the hydrochloric acid solution in step S2 is 2 mol / L; The ratio of the acidic solution to the alkali-treated intermediate product in step S1 is 80 mL: 1 g; The acid treatment temperature is 60°C, and the treatment time is 0.2 hours; The stirring speed during the acid treatment process is 100 r / min; The filtration membrane used in step S2 is the same as the filtration membrane used in step S1. In step S2, the drying temperature is 60℃, the heating rate is 3℃ / min, and the holding time is 12 hours. The crucible mentioned in step S3 is made of corundum crucible; In step S3, the calcination temperature is 550℃, the powder layer thickness is 1mm, the calcination heating rate is 10℃ / min, and the holding time is 30 min; the calcination atmosphere is air.

[0028] The core-shell structured TiO2 powder prepared above has D 50 It is 4358nm; The core phase of the core-shell structured TiO2 powder prepared above is rutile TiO2, and the shell phase is anatase TiO2. The thickness of the anatase phase layer is 965 nm, and the coefficient of variation (CV) is 10.6%. The thickness of the heterojunction interface layer formed between the core phase and the shell phase is 452 nm, and the coefficient of variation (CV) is 6.5%. The core-shell structured TiO2 powder prepared above has a specific surface area of ​​43.6 m². 2 / g; under ultraviolet light irradiation, the degradation rate of organic pollutants (bisphenol A, concentration 10 ppm) reaches 90%.

[0029] Compared to the original rutile powder, the core-shell structure of TiO2 powder has a photocatalytic efficiency that is 6 times higher and an adsorption performance that is 8 times higher than that of the original rutile powder.

[0030] Example 2 S1 Alkali Treatment: Rutile TiO2 powder and sodium hydroxide solution are mixed evenly and placed in a high-pressure reactor for hydrothermal reaction under constant temperature and stirring conditions. After the reaction is completed, solid-liquid separation is performed by vacuum filtration. During the vacuum filtration process, the filtrate is repeatedly washed with deionized water until it is neutral. After drying, the alkali-treated product is obtained. S2 Acid Treatment: The alkaline-treated product obtained in step S1 is dispersed in hydrochloric acid solution and acid-treated under constant temperature and stirring conditions; after acid treatment, solid-liquid separation is performed by vacuum filtration. During vacuum filtration, the product is repeatedly washed with deionized water until the filtrate is neutral and then dried to obtain the acid-treated product. S3 Heat treatment: The acid-treated product obtained in step S2 is spread evenly in a crucible and calcined; after calcination, it is cooled to room temperature to obtain the TiO2 core-shell structure powder.

[0031] In step S1, the rutile TiO2 powder is mixed evenly with the alkaline solution, and the mass ratio of rutile TiO2 powder, alkaline substance, and water is 1:20:25; rutile TiO2 powder D 50 The wavelength was 2341 nm; the sodium hydroxide solid used was of analytical grade. The reactor and lining used for the hydrothermal reaction are stainless steel reactors and polytetrafluoroethylene (PTFE) linings; The hydrothermal reaction temperature is 180℃, and the hydrothermal reaction time is 20 hours; the stirring speed during the hydrothermal reaction is 100 r / min. The filter membrane used for filtration in step S1 is a polyethersulfone (PES) filter membrane with a pore size of 0.03 μm. In step S1, the drying temperature is 60°C, the heating rate is 3°C / min, and the holding time is 12 hours.

[0032] The concentration of the hydrochloric acid solution in step S2 is 2 mol / L; The ratio of the acidic solution to the alkali-treated intermediate product in step S1 is 60 ml : 1 g; The acid treatment temperature is 60°C, and the treatment time is 0.2 hours; The stirring speed during the acid treatment process is 100 r / min; The filtration membrane used in step S2 is the same as the filtration membrane used in step S1. In step S2, the drying temperature is 60℃, the heating rate is 3℃ / min, and the holding time is 12 hours. The crucible mentioned in step S3 is made of corundum crucible; In step S3, the calcination temperature is 550℃, the powder layer thickness is 1mm, the calcination heating rate is 10℃ / min, and the holding time is 60 min; the calcination atmosphere is air.

[0033] The core-shell structured TiO2 powder prepared above has D 50 It is 3098nm; The core phase of the core-shell structured TiO2 powder prepared above is rutile TiO2, and the shell phase is anatase TiO2. The thickness of the anatase phase layer is 859 nm, and the coefficient of variation (CV) is 13.6%. The thickness of the heterojunction interface layer formed between the core phase and the shell phase is 351 nm, and the coefficient of variation (CV) is 8.4%. The core-shell structured TiO2 powder prepared above has a specific surface area of ​​58.3 m². 2 / g; under ultraviolet light irradiation, the degradation rate of organic pollutants (bisphenol A, concentration 10 ppm) reached 94%.

[0034] Compared to the original rutile powder, the core-shell structure of this TiO2 powder has an 8-fold increase in photocatalytic efficiency and a 10-fold increase in adsorption performance.

[0035] Example 3 S1 Alkali Treatment: Rutile TiO2 powder and sodium hydroxide solution are mixed evenly and placed in a high-pressure reactor for hydrothermal reaction under constant temperature and stirring conditions. After the reaction is completed, solid-liquid separation is performed by vacuum filtration. During the vacuum filtration process, the filtrate is repeatedly washed with deionized water until it is neutral. After drying, the alkali-treated product is obtained. S2 Acid Treatment: The alkaline-treated product obtained in step S1 is dispersed in hydrochloric acid solution and acid-treated under constant temperature and stirring conditions; after acid treatment, solid-liquid separation is performed by vacuum filtration. During vacuum filtration, the product is repeatedly washed with deionized water until the filtrate is neutral and then dried to obtain the acid-treated product. S3 Heat treatment: The acid-treated product obtained in step S2 is spread evenly in a crucible and calcined; after calcination, it is cooled to room temperature to obtain the TiO2 core-shell structure powder.

[0036] In step S1, the rutile TiO2 powder is mixed evenly with the alkaline solution, and the mass ratio of rutile TiO2 powder, alkaline substance, and water is 1:15:25; rutile TiO2 powder D 50 The wavelength was 2341 nm; the sodium hydroxide solid used was of analytical grade. The reactor and lining used for the hydrothermal reaction are stainless steel reactors and polytetrafluoroethylene (PTFE) linings; The hydrothermal reaction temperature is 160℃, and the hydrothermal reaction time is 15 hours; the stirring speed during the hydrothermal reaction is 100 r / min. The filter membrane used for filtration in step S1 is a polyethersulfone (PES) filter membrane with a pore size of 0.03 μm. In step S1, the drying temperature is 60°C, the heating rate is 3°C / min, and the holding time is 12 hours.

[0037] The concentration of the hydrochloric acid solution in step S2 is 2 mol / L; The ratio of the acidic solution to the alkali-treated intermediate product in step S1 is 90 ml : 1 g; The acid treatment temperature is 60°C, and the treatment time is 0.2 hours; The stirring speed during the acid treatment process is 100 r / min; The filtration membrane used in step S2 is the same as the filtration membrane used in step S1. In step S2, the drying temperature is 60℃, the heating rate is 3℃ / min, and the holding time is 12 hours. The crucible mentioned in step S3 is made of corundum crucible; In step S3, the calcination temperature is 550℃, the powder layer thickness is 1mm, the calcination heating rate is 10℃ / min, and the holding time is 60 min; the calcination atmosphere is air.

[0038] The core-shell structured TiO2 powder prepared above has D 50 It is 5538nm; The core phase of the core-shell structured TiO2 powder prepared above is rutile TiO2, and the shell phase is anatase TiO2. The thickness of the anatase phase layer is 904 nm, and the coefficient of variation (CV) is 9.7%. The thickness of the heterojunction interface layer formed between the core and shell phases is 418 nm, and the coefficient of variation (CV) is 6.1%. The core-shell structured TiO2 powder prepared above has a specific surface area of ​​30.3 m². 2 / g, under ultraviolet light irradiation, the degradation rate of organic pollutant (bisphenol A, concentration 10ppm) reaches 83%.

[0039] Compared to the original rutile powder, the core-shell structure of this TiO2 powder has a 3-fold higher photocatalytic efficiency and a 3-fold higher adsorption performance.

[0040] The preparation method of this application requires all three steps: alkali treatment, acid treatment, and heat treatment. Compared with materials obtained by only alkali treatment or acid treatment plus heat treatment, the photocatalytic efficiency and adsorption performance of the materials obtained by this preparation method are improved by more than 2 times.

[0041] In summary, this application provides a simple, low-cost, and easily controllable method for preparing "rutile@anatase" core-shell structured TiO2 powder. The prepared material exhibits stable performance and significantly enhanced photocatalytic activity, demonstrating significant practical application value and broad prospects for promotion.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification illustrate the principles of the invention. Various changes and modifications can be made to this application without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention claimed in this application.

Claims

1. A method for preparing TiO2 powder with a rutile@anatase core-shell structure, characterized in that: The preparation method comprises the following steps: S1: base treatment process After the rutile phase TiO2 powder is uniformly mixed with the alkaline solution, the mixture is placed in a high-pressure reaction kettle and subjected to hydrothermal reaction under constant temperature stirring; after the reaction is completed, solid-liquid separation is performed, and repeated washing with deionized water is performed until the washing liquid is neutral; and after drying, the base treatment product is obtained; S2: acid treatment process The base treatment product obtained in step S1 is dispersed in an acidic solution, and acid treatment is performed under constant temperature stirring; after the acid treatment is completed, solid-liquid separation is performed, and repeated washing with deionized water is performed until the washing liquid is neutral; and after drying, the acid treatment product is obtained; S3: heat treatment process The acid treatment product obtained in step S2 is laid flat in a crucible and subjected to calcination treatment; after calcination is completed, the furnace is naturally cooled to room temperature, and a TiO2 powder with a rutile@anatase core-shell structure is obtained.

2. The preparation method according to claim 1, wherein: In step S1, the basic solution is composed of a basic substance and water, the mass ratio of the rutile TiO2 powder, the basic substance and water is 1:(5-25):(15-100); the rutile TiO2 powder D 50 is 100-500000nm; The alkaline solution is configured from at least one of sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and cesium hydroxide (CsOH); the temperature of the hydrothermal reaction is 80-200°C, the time is 2-200 hours, and the stirring speed is 10-1000 r / min; The material of the filter membrane for suction filtration is selected from one or more of mixed cellulose ester (MCE), polyether sulfone (PES), nylon (Nylon), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polycarbonate track etching (PCTE / PETE), and the pore size of the filter membrane is ≤0.3 μm; The drying temperature is 30-200°C, the temperature rising rate is 1-20°C / min, and the constant temperature time is 0.5-24 hours.

3. The preparation method according to claim 1, wherein: In step S2, the acidic solution is an aqueous solution of inorganic acid, and the inorganic acid is selected from any one or a combination of multiple of hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), and perchloric acid (HClO4); The concentration of the acidic solution is 0.1-20 mol / L; The ratio of the base treatment product to the acidic solution is ≥30 mL of the acidic solution per gram of the base treatment product; The temperature of the acid treatment is 20-95°C, and the time is 0.1-24 hours; The stirring speed of the acid treatment is 10-1000 r / min; The material of the filter membrane for suction filtration is selected from one or more of mixed cellulose ester (MCE), polyether sulfone (PES), nylon (Nylon), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polycarbonate track etching (PCTE / PETE), and the pore size of the filter membrane is ≤0.3 μm; The drying temperature is 30-200°C, the temperature rising rate is 1-20°C / min, and the constant temperature time is 0.5-24 hours.

4. The preparation method according to claim 1, wherein: In step S3, the material of the crucible is an inert material that can be used for calcination in an air atmosphere, and is selected from any one of corundum crucible, silicon carbide crucible, quartz crucible, and boron nitride crucible. In the calcination process, the powder is laid flat with a thickness of ≤1 mm, the calcination temperature is 200-950℃, the heating rate is 1-20℃ / min, the constant temperature time is 5-500 min, and the calcination atmosphere is air.

5. The TiO2 powder with rutile@anatase core-shell structure prepared by the preparation method in any one of claims 1-4, characterized in that: The D50 of the TiO2 powder of the core-shell structure is 100-500000 nm. 50 100-500000 nm. The core phase of the TiO2 powder with core-shell structure is rutile TiO2, the shell phase is anatase TiO2, the thickness of the anatase phase layer is 1-1000 nm, and the thickness variation coefficient CV is ≤15%; the thickness of the heterojunction interface layer formed between the core phase and the shell phase is 1-500 nm, and the thickness variation coefficient CV is ≤10%; The TiO2 powder of the core-shell structure has a specific surface area of 1-80 m 2 / g.

6. The application of the TiO2 powder with rutile@anatase core-shell structure prepared by the preparation method in any one of claims 1-4 in water treatment.

7. The application of the TiO2 powder with rutile@anatase core-shell structure prepared by the preparation method in any one of claims 1-4 in photocatalytic degradation of organic pollutants.

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