A stable crystalline photocatalyst and a preparation method and application thereof

Abstract

The application discloses a kind of stable crystal form photocatalyst and its preparation method, application, belong to photocatalyst technical field, the catalyst is 1-ethyl-3-methyl imidazole tetrafluoroborate ion liquid assisted La doped TiO2 Photocatalyst, La doping ratio 0.12-0.13%, ion liquid content 12-13 mL / mg.It is prepared using sol-gel method, by precisely controlling A, B liquid ratio and 595-605 DEG C, 1.8-2.2h calcination process, realize lattice defect controllable and crystal form stable.When applied, the mass ratio of catalyst and rhodamine B is 99-101:1, and rhodamine B in wastewater can be efficiently degraded under illumination for ≥80 min, with a degradation rate of ≥92%.The degradation rate is still ≥88% after being reused for 5 times.The catalyst has stable crystal form, high photocatalytic efficiency, environmental protection and economy, and is suitable for treating wastewater containing rhodamine B in multiple industries.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a stable crystalline photocatalyst, its preparation method, and its application. Background Technology

[0002] With the acceleration of global industrialization and the continuous expansion of industrial production scale, wastewater discharge has experienced explosive growth, and the types of pollutants have become increasingly complex and diverse, covering a variety of recalcitrant and harmful substances such as dyes, heavy metals, and organic solvents. Among them, Rhodamine B, a typical organic dye pollutant widely used in industries such as textiles, printing, and pharmaceuticals, is characterized by strong chemical stability and difficulty in biodegradation. Once it enters freshwater bodies, it not only reduces the water's light transmittance and disrupts the balance of aquatic ecosystems, but also accumulates through the food chain, posing a serious threat to human health. Therefore, it has become one of the key targets for treatment in the field of industrial wastewater.

[0003] In the treatment of Rhodamine B wastewater, photocatalytic oxidation technology has gradually become a research hotspot due to its advantages such as high degradation efficiency, no secondary pollution, and mild operating conditions. Titanium dioxide (TiO2), as a high-performance photocatalyst, is widely used in industrial wastewater treatment and air purification due to its good chemical stability, high catalytic activity, non-toxicity, and low cost, especially showing good application potential in the degradation of organic dye wastewater such as Rhodamine B.

[0004] Studies have shown that the photocatalytic material TiO2 has a wide bandgap and low solar energy utilization. Furthermore, photocarriers recombine easily, leading to a low quantum yield. Therefore, metal ion doping of TiO2 is generally chosen; however, the photocatalytic activity of metal ion-doped TiO2 is related to various factors such as the type and concentration of the metal ions, the preparation method, and post-treatment. In catalytic reaction experiments, ionic liquids, as a relatively mild solvent, can maintain the activity of the catalyst for a longer time than a single catalyst. As a reaction medium, ionic liquids have the advantages of a wide liquid range and negligible vapor pressure. They are also reusable, and the sol-gel method can uniformly disperse titanium alkoxides in ionic solvents to form low-viscosity solutions, and can also uniformly and quantitatively mix trace elements, obtaining molecularly homogeneous low-viscosity solutions in a short time.

[0005] However, in the existing technology, titanium dioxide catalysts doped with metal ions prepared by the sol-gel method have unstable photocatalytic efficiency because various factors such as calcination temperature, amount of ionic liquid added, and amount of metal ion doping during the preparation process can affect the crystal form of the catalyst.

[0006] Therefore, there is an urgent need for a titanium dioxide catalyst doped with metal ions prepared by the sol-gel method that can obtain a stable crystal form, thereby ensuring stable efficiency of photocatalysis. Summary of the Invention

[0007] The purpose of this invention is to provide a stable crystal form photocatalyst, its preparation method, and its application, in order to solve the technical problems of low photodegradation efficiency and incomplete catalyst reaction caused by the unstable crystal structure of novel titanium dioxide catalysts doped with metal ions obtained by the sol-gel method.

[0008] In a first aspect, the present invention provides a stable crystal form of photocatalyst, which is an ionic liquid-assisted La-doped TiO2 photocatalyst, wherein the ionic liquid is a 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid, the content of the 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid in the ionic liquid-assisted La-doped TiO2 photocatalyst is 12-13 mL / mg, and the La doping ratio is 0.12-0.13%.

[0009] The photocatalyst is a La-doped TiO2 photocatalyst assisted by an ionic liquid. The core of this approach is to precisely control the La doping ratio and the amount of ionic liquid added to achieve synergistic optimization of the crystal lattice and crystal form, thereby enhancing photocatalytic performance. Details are as follows: 1. Ionic liquid: 1-Ethyl-3-methylimidazolium tetrafluoroborate is used, and the amount added is controlled at 12-13 mL / mg (relative to the total amount of photocatalyst). The imidazole ring and tetrafluoroborate in its molecular structure can form a weak interaction with the TiO2 precursor, thereby regulating lattice growth and crystal form transformation. 2. La doping ratio: precisely controlled at 0.12-0.13%, this ratio represents La... 3+ The optimal threshold for embedding into the TiO2 lattice is used to achieve a dynamic balance between lattice defects and crystal stability. 3. Core structural characteristics: La 3+ The ionic liquid is uniformly embedded in the TiO2 anatase lattice through lattice substitution, adsorbed on the lattice surface and filling the grain boundary gaps, ultimately forming a composite structure with "controllable lattice defects, stable single crystal form, and fully exposed active sites".

[0010] I. The mechanism of La doping ratio regulation and its impact on lattice, crystal form and photodegradation efficiency The La doping ratio directly determines the number, distribution, and crystal purity of TiO2 lattice defects, thus dominating its photocatalytic performance. The specific mechanism is as follows: (1) Effect of insufficient La doping ratio (<0.12%): At this time, La 3+The number of embedded TiO2 lattice sites is limited, resulting in insufficient lattice defect sites (electron traps) and a minimal decrease in the recombination probability of photogenerated electrons and holes (still remaining above 60% of that in pure TiO2); simultaneously, a small amount of La... 3+ It is difficult to effectively suppress the transformation of TiO2 crystal form. During calcination, the transformation from anatase phase to rutile phase (rutile phase ratio > 5%) is likely to occur, resulting in a reduction of active sites. The degradation rate of Rhodamine B can only reach about 70%.

[0011] (2) Effect of suitable La doping ratio (0.12-0.13%): At this ratio, La 3+ Ti that can be uniformly embedded in the TiO2 lattice 4+ Site—La 3+ The ionic radius (0.103 nm) is greater than that of Ti. 4+ (0.068 nm), after embedding, it induces slight local lattice distortion, forming uniformly distributed defect sites and oxygen vacancies (charge compensation effect); these defect sites can efficiently capture photogenerated electrons, reducing the carrier recombination probability to below 30% of that of pure TiO2; at the same time, La 3+ Occupying high-energy sites in the crystal lattice increases the crystallization energy of the anatase phase, inhibits crystal form transformation, and maintains the purity of the anatase phase at over 98%. The synergy between sufficient active sites and a single stable crystal form increases the degradation rate of Rhodamine B to over 92%.

[0012] (3) Effect of excessive La doping ratio (>0.13%): Excess La 3+ Unable to be fully embedded in the TiO2 lattice, some La 3+ These particles accumulate on the crystal lattice surface or at grain boundaries, leading to excessive lattice distortion (lattice constant deviating from the ideal value >3%) and forming disordered defects. These disordered defects become recombination centers for photogenerated carriers, accelerating electron-hole recombination. Simultaneously, the La particles accumulated on the surface... 3+ It can mask active sites and may induce the formation of rutile phase (rutile phase ratio > 10%), ultimately leading to a decrease in photodegradation efficiency to below 80%.

[0013] II. The mechanism for regulating the amount of ionic liquid added and its effects on crystal lattice, crystal form and photodegradation efficiency The amount of ionic liquid added affects crystal stability and active site exposure by regulating the lattice growth rate and grain boundary interactions. The specific mechanism is as follows: (1) Effect of insufficient ionic liquid addition (<12mL / mg): A small amount of ionic liquid cannot completely cover the surface of TiO2 precursor, making it difficult to suppress the aggregation phenomenon during the crystal growth process, resulting in the aggregation of crystal particles (particle size >50nm), and some crystal defects and active sites are masked; at the same time, the ionic liquid has insufficient inhibitory effect on crystal transformation, and the purity of anatase phase drops to below 90% after calcination, the proportion of rutile phase increases, the photogenerated carrier transport path is blocked, and the degradation rate of Rhodamine B is only about 75%.

[0014] (2) Effect of appropriate ionic liquid addition (12-13 mL / mg): At this addition level, ionic liquid molecules can be uniformly adsorbed on the TiO2 lattice surface. Through the weak hydrogen bonding between the imidazole ring and the TiO2 precursor, the lattice growth rate is slowed down, particle agglomeration is avoided (particle size controlled at 20-30 nm), and the active sites are fully exposed. At the same time, tetrafluoroborate ions can fill the intergranular gaps, reduce the grain boundary energy, inhibit the transformation of the anatase phase to the rutile phase, and maintain the single and stable crystal form. In addition, the ionic liquid can also react with La 3+ The formation of weak coordination promotes La 3+ Uniformly embedded in the crystal lattice avoids local aggregation and further optimizes the distribution of lattice defects. Ultimately, the synergistic optimization of the crystal lattice, crystal form and active sites keeps the photodegradation efficiency above 92% and significantly improves the reaction stability.

[0015] (3) Effect of excessive ionic liquid addition (>13 mL / mg): Excessive ionic liquid tends to form a multilayer adsorption film on the TiO2 lattice surface, encapsulating the active sites and hindering the contact between Rhodamine B molecules and the catalyst surface; at the same time, excessive ionic liquid may react with La 3+ Formation of strong coordination, inhibiting La 3+ The embedding of the ionic liquid into the crystal lattice results in insufficient lattice defect sites. In addition, the excessive ionic liquid does not decompose completely during calcination, and the residual organic matter covers the lattice surface, reducing the light absorption efficiency and ultimately causing the degradation rate of Rhodamine B to drop below 85%.

[0016] III. Synergistic Regulation Mechanism of La Doping Ratio and Ionic Liquid Addition Amount The La doping ratio and the amount of ionic liquid added achieve maximum photodegradation efficiency through the synergistic effect of "lattice defect regulation - crystal form stabilization - active site exposure": the appropriate La doping ratio provides uniform and controllable lattice defects, laying the foundation for carrier separation; the matched amount of ionic liquid added inhibits lattice aggregation and crystal form transformation, ensuring that defect sites and active sites are fully exposed; the two work together to form a virtuous cycle of "uniform lattice defects - stable single crystal form - sufficient active sites - high light absorption efficiency", which increases the quantum yield of the photocatalytic system to more than 2.5 times that of pure TiO2, significantly enhancing the degradation ability of Rhodamine B.

[0017] Secondly, the present invention provides the application of the above-mentioned stable crystal form of photocatalyst in the degradation of wastewater containing Rhodamine B.

[0018] Further, the above application specifically includes the following steps: A1, adding the ionic liquid-assisted La-doped TiO2 photocatalyst to the Rhodamine B solution, wherein the mass ratio of the ionic liquid-assisted La-doped TiO2 photocatalyst to the Rhodamine B in the Rhodamine B solution is (99~101):1; A2, then irradiating with light for a time not less than 80 min, thereby completing the degradation of Rhodamine B.

[0019] This photocatalyst optimizes its lattice-crystal form-photocatalytic performance through the synergistic regulation of the La doping ratio and the amount of ionic liquid added. It is specifically designed for the efficient degradation of wastewater containing Rhodamine B. The specific application steps are as follows: A1. Feeding and Mixing: Add the photocatalyst to the Rhodamine B solution at a mass ratio of (99~101):1—ensuring sufficient contact between Rhodamine B molecules and the active sites (lattice defects and oxygen vacancies) on the catalyst surface; A2. Photocatalytic Degradation: Irradiate the mixture under a UV lamp for at least 80 minutes—in the first 10 minutes, ·OH and ·O2... - The conjugated structure of Rhodamine B is rapidly disrupted; within 10-80 min, the active sites of the lattice continue to catalyze the decomposition of intermediate products; after 80 min, the overall degradation of the solution tends to reach equilibrium, with no significant changes.

[0020] Thirdly, the present invention also provides a method for preparing the above-mentioned stable crystal form of photocatalyst, comprising the following steps: S1, adding tetrabutyl titanate to anhydrous ethanol and then adding glacial acetic acid and stirring to obtain solution A for later use; S2, adding La(NO3)3 solution to anhydrous ethanol and then adding distilled water and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid in sequence to obtain solution B; S3, adding solution B dropwise to solution A and stirring to obtain gel; S4, drying and cooling after standing to obtain coarse material, grinding the coarse material and calcining it and then cooling it to room temperature to obtain the ionic liquid-assisted La-doped TiO2 photocatalyst.

[0021] Furthermore, the volume ratio of liquid A to liquid B is (2.9-3):1.

[0022] Furthermore, in S4, the calcination temperature is 595-605°C.

[0023] Furthermore, in S4, the calcination time is 1.8-2.2 h.

[0024] Furthermore, the concentration of the La(NO3)3 solution is 0.9-1.1 mol / L.

[0025] Further, in solution A, the volume ratio of tetrabutyl titanate to anhydrous ethanol is 1:(2.8-3.2), and the volume ratio of glacial acetic acid to anhydrous ethanol is (1.1-1.3):3.

[0026] Further, in solution B, the volume ratio of anhydrous ethanol to distilled water is (6-8):10, the volume ratio of La(NO3)3 solution to distilled water is (1.8-2.2):100, and the volume ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid to distilled water is (4.8-5.5):100.

[0027] This method employs the sol-gel method, achieving directional control of the lattice and crystal form through precise control of the La doping ratio, ionic liquid addition amount, and process parameters. Specific effects are as follows: S1—Glacial acetic acid acts as a chelating agent, inhibiting the excessively rapid hydrolysis of tetrabutyl titanate and preventing uneven lattice growth; S2—Ensuring La… 3+ Evenly dispersed with ionic liquid; S3 – slow dropwise addition ensures La 3 + Uniformly embedded in the crystal lattice to avoid excessively high local concentrations; S4 – drying to remove solvent and prevent lattice cracking; calcination temperature and time ensure La 3+ It is fully embedded in the crystal lattice, promotes the crystallization of the anatase phase, and maintains crystal stability.

[0028] The beneficial effects of this invention are as follows: 1. Precise and efficient control of lattice and crystal form: By precisely controlling the La doping ratio at 0.12-0.13% and the amount of ionic liquid added at 12-13 mL / mg, uniform and controllable lattice defects of TiO2 are achieved (the distribution of oxygen vacancies and substitution defects is regular), while maintaining the purity of the anatase phase of more than 98%, thus completely solving the core problems of disordered lattice distortion and crystal form transformation (coexistence of anatase phase and rutile phase) in the existing technology.

[0029] 2. Significantly improved photocatalytic degradation efficiency: The synergy between lattice defects and the single anatase crystal form reduces the probability of photogenerated electron-hole recombination to less than 30% of that of pure TiO2. The degradation rate of Rhodamine B can reach up to 92.38%, which is far superior to that of pure TiO2 (46.19%) and ordinary La-doped TiO2 (68.35%). The quantum yield is increased to more than 2.5 times that of pure TiO2.

[0030] 3. Strong reaction stability and durability: The uniform crystal structure and stable crystal form design ensure that the degradation rate of the catalyst is still ≥88% after 5 reuses, and the performance difference between batches is ≤2%, which can meet the long-term operation requirements of continuous industrial wastewater treatment and avoid the problems of easy deactivation and large performance fluctuation of existing catalysts.

[0031] 4. The preparation process is controllable and easy to scale up: The sol-gel method combined with precise ratio control (the volume ratio of raw materials and the concentration threshold are clear) enables the directional control of the crystal lattice and crystal form. The process steps are clear, the parameters are easy to control, and there are no complex equipment requirements, making it suitable for industrial mass production.

[0032] 5. Environmentally friendly and economical with no secondary pollution: Ionic liquids can be recycled and reused, raw materials (tetrabutyl titanate, La(NO3)3, etc.) are readily available and cost-controllable, and the preparation process does not emit toxic or harmful substances; the final products after the catalyst degrades Rhodamine B are inorganic small molecules such as CO2 and H2O, with no secondary pollution, which meets the requirements of environmental protection.

[0033] 6. Wide applicability: It can efficiently treat wastewater containing Rhodamine B with a concentration of 1-10 mg / L, and is suitable for different water quality scenarios in industries such as textiles, printing, and pharmaceuticals. The feeding ratio (catalyst to Rhodamine B mass ratio of 99~101:1) is easy to operate and does not require a complicated pretreatment process.

[0034] 7. Significant synergistic effect of components: La 3+ The lattice regulation effect of the liquid forms a virtuous cycle with the crystal form stability and particle dispersion effect of the ionic liquid, which not only ensures the full exposure of active sites, but also optimizes the light absorption and carrier transport efficiency, thus achieving synergistic enhancement of "lattice-crystal form-photocatalytic performance". Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 The images shown are scanning electron microscope (SEM) images of the catalysts prepared in Example 1 and Comparative Example 1 of the present invention, where a is an SEM image of the catalyst prepared in Comparative Example 1 and b is an SEM image of the catalyst prepared in Example 1. Figure 2 X-ray diffraction patterns of the catalysts prepared in Example 1 and Comparative Example 1 in Experimental Example 2 of the present invention, wherein (a) is the X-ray diffraction pattern of the catalyst prepared in Example 1 and (b) is the X-ray diffraction pattern of the catalyst prepared in Comparative Example 1. Figure 3 The infrared spectra of the catalysts prepared in Example 1 and Comparative Example 1 in Experimental Example 3 of the present invention are shown in the figure. In the figure, a is the infrared spectrum of the catalyst prepared in Example 1 and b is the infrared spectrum of the catalyst prepared in Comparative Example 1. Figure 4The above are DTA-TG characterization diagrams of the catalysts prepared in Example 1 and Comparative Example 1 in Experimental Example 4 of the present invention, where (a) is the differential thermal analysis line of ionic liquid-assisted La-doped titanium dioxide, and (b) is the thermogravimetric analysis line of ionic liquid-assisted La-doped titanium dioxide. Figure 5 This is a graph showing the effect of ionic liquid content on degradation rate in Experiment Example 5 of this invention; Figure 6 This is a graph showing the effect of La doping ratio on degradation rate in Experiment Example 6 of this invention; Figure 7 This is a graph showing the effect of temperature on the degradation rate in Experiment Example 7 of this invention; Figure 8 This is a graph showing the effect of catalyst dosage on degradation rate in Experiment Example 8 of the present invention; Figure 9 The graph shows the effect of time on the degradation rate in Experiment Example 9 of this invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0039] The features and performance of the present invention will be further described in detail below with reference to embodiments. Example 1 raw material components Tetrabutyl titanate (TBOT): AR grade, density 0.996 g / mL, specific volume 10.05 mL (approximately 10.0 g), is the core component of solution A; Anhydrous ethanol (EtOH): AR grade, density 0.789 g / mL, specific volume 37.15 mL (approximately 29.31 g), of which 30.15 mL is added to solution A and 7.0 mL to solution B, serving as the dispersion medium; Glacial acetic acid (HAc): AR grade, density 1.049 g / mL, specific volume 12.06 mL (approximately 12.65 g), is the chelating agent in solution A; Lanthanum nitrate solution: concentration 1.0 mol / L (prepared with La(NO3)3·6H2O), specific volume 0.2 mL (containing La(NO3)3·6H2O) 0.0866g), serving as the doping source for solution B; distilled water (H2O): deionized water, specifically 10.0mL (10.0g), used as the hydrolysis medium; 1-ethyl-3-methylimidazolium tetrafluoroborate (IL): AR grade, density 1.29g / mL, specifically 0.515mL (approximately 0.664g), used as a crystal form stabilizer.

[0040] Preparation method S1. Preparation of Solution A: Add 10.05 mL of tetrabutyl titanate to 30.15 mL of anhydrous ethanol, stir until homogeneous, then add 12.06 mL of glacial acetic acid, and continue magnetic stirring for 10 min to obtain a homogeneous and transparent Solution A (TBOT to anhydrous ethanol volume ratio 1:3.0, glacial acetic acid to anhydrous ethanol volume ratio 1.2:3); S2. Preparation of Solution B: Add 0.2 mL of 1.0 mol / L lanthanum nitrate solution to 7.0 mL of anhydrous ethanol, stir to dissolve, then add 10.0 mL of distilled water and 0.515 mL of ionic liquid sequentially, and continue stirring for 15 min to obtain a homogeneous Solution B (anhydrous ethanol to distilled water volume ratio 7:10, lanthanum nitrate solution to distilled water volume ratio 2.0:100, ionic liquid to distilled water volume ratio 5.15:100); S3. Sol-gel formation: Slowly add Solution B dropwise to Solution A at a rate of 0.02 mL / s. In the middle (volume ratio of liquid A to liquid B 2.95:1), after the addition is complete, the mixture is continuously stirred magnetically for 4 hours to form a uniform and transparent gel; S4, post-treatment: after the gel is left to stand for 24 hours, it is placed in an electric thermostatic drying oven and dried at 100℃ for 2 hours. After cooling to room temperature, it is ground to obtain coarse material; the coarse material is placed in a muffle furnace and calcined at 600℃ for 2.0 hours. After naturally cooling to room temperature, a stable crystal form of photocatalyst (La doping ratio 0.125%, ionic liquid addition amount 12.5mL / mg) is obtained.

[0041] Example 2 raw material components Tetrabutyl titanate (TBOT): AR grade, density 0.996 g / mL, specific volume 9.23 mL (approximately 9.20 g), is the core component of solution A; Anhydrous ethanol (EtOH): AR grade, density 0.789 g / mL, specific volume 37.54 mL (approximately 29.62 g), of which 29.54 mL is added to solution A and 8.0 mL to solution B, serving as the dispersion medium; Glacial acetic acid (HAc): AR grade, density 1.049 g / mL, specific volume 12.73 mL (approximately 13.35 g), is the chelating agent in solution A; Lanthanum nitrate solution: concentration 1.1 mol / L (prepared with La(NO3)3·6H2O), specific volume 0.22 mL (containing La(NO3)3·6H2O) 0.103g), serving as the doping source for solution B; distilled water (H2O): deionized water, specifically 10.0mL (10.0g), used as the hydrolysis medium; 1-ethyl-3-methylimidazolium tetrafluoroborate (IL): AR grade, density 1.29g / mL, specifically 0.55mL (approximately 0.710g), serving as the crystal form stabilizer.

[0042] Preparation method S1. Preparation of Solution A: Add 9.23 mL of tetrabutyl titanate to 29.54 mL of anhydrous ethanol, stir until homogeneous, then add 12.73 mL of glacial acetic acid, and continue magnetic stirring for 10 min to obtain a homogeneous and transparent Solution A (TBOT to anhydrous ethanol volume ratio 1:3.2, glacial acetic acid to anhydrous ethanol volume ratio 1.3:3); S2. Preparation of Solution B: Add 0.22 mL of 1.1 mol / L lanthanum nitrate solution to 8.0 mL of anhydrous ethanol, stir to dissolve, then add 10.0 mL of distilled water and 0.55 mL of ionic liquid sequentially, and continue stirring for 15 min to obtain a homogeneous Solution B (anhydrous ethanol to distilled water volume ratio 8:10, lanthanum nitrate solution to distilled water volume ratio 2.2:100, ionic liquid to distilled water volume ratio 5.5:100); S3. Sol-gel formation: Dissolve Solution B at 0.02... The solution was slowly added dropwise to solution A at a rate of mL / s (the volume ratio of solution A to solution B is 3.0:1). After the addition was complete, the solution was continuously stirred magnetically for 4 h to form a uniform and transparent gel. S4, Post-treatment: After the gel was allowed to stand for 24 h, it was placed in an electric thermostatic drying oven and dried at 100℃ for 2 h. After cooling to room temperature, it was ground to obtain coarse material. The coarse material was placed in a muffle furnace and calcined at 605℃ for 1.8 h. After naturally cooling to room temperature, a photocatalyst with a stable crystal form (La doping ratio 0.13%, ionic liquid addition amount 13.0 mL / mg) was obtained.

[0043] Example 3 raw material components Tetrabutyl titanate (TBOT): AR grade, density 0.996 g / mL, specific volume 10.98 mL (approximately 10.94 g), is the core component of solution A; Anhydrous ethanol (EtOH): AR grade, density 0.789 g / mL, specific volume 36.74 mL (approximately 28.99 g), of which 30.74 mL is added to solution A and 6.0 mL to solution B, serving as the dispersion medium; Glacial acetic acid (HAc): AR grade, density 1.049 g / mL, specific volume 11.38 mL (approximately 11.94 g), is the chelating agent in solution A; Lanthanum nitrate solution: concentration 0.9 mol / L (prepared with La(NO3)3·6H2O), specific volume 0.18 mL (containing 0.070 mol / L La(NO3)3·6H2O). g), serving as the doping source for solution B; distilled water (H2O): deionized water, specifically 10.0 mL (10.0 g), used as the hydrolysis medium; 1-ethyl-3-methylimidazolium tetrafluoroborate (IL): AR grade, density 1.29 g / mL, specifically 0.48 mL (approximately 0.619 g), used as a crystal form stabilizer.

[0044] Preparation method S1. Preparation of Solution A: Add 10.98 mL of tetrabutyl titanate to 30.74 mL of anhydrous ethanol, stir until homogeneous, then add 11.38 mL of glacial acetic acid, and continue magnetic stirring for 10 min to obtain a homogeneous and transparent Solution A (TBOT to anhydrous ethanol volume ratio 1:2.8, glacial acetic acid to anhydrous ethanol volume ratio 1.1:3); S2. Preparation of Solution B: Add 0.18 mL of 0.9 mol / L lanthanum nitrate solution to 6.0 mL of anhydrous ethanol, stir until dissolved, then add 10.0 mL of distilled water and 0.48 mL of ionic liquid sequentially, and continue stirring for 15 min to obtain a homogeneous Solution B (anhydrous ethanol to distilled water volume ratio 6:10, lanthanum nitrate solution to distilled water volume ratio 6:10, glacial acetic acid to distilled water volume ratio 1.1:3). S3, Sol-gel formation: Solution B is slowly added dropwise to solution A at a rate of 0.02 mL / s (volume ratio of solution A to solution B is 2.9:1). After the addition is complete, the mixture is continuously magnetically stirred for 4 hours to form a uniform and transparent gel. S4, Post-treatment: After the gel is allowed to stand for 24 hours, it is placed in an electric thermostatic drying oven and dried at 100℃ for 2 hours. After cooling to room temperature, it is ground to obtain coarse material. The coarse material is placed in a muffle furnace and calcined at 595℃ for 2.2 hours. After naturally cooling to room temperature, a stable crystal form of photocatalyst (La doping ratio 0.12%, ionic liquid addition amount 12.0 mL / mg) is obtained.

[0045] Example 4 raw material components Tetrabutyl titanate (TBOT): AR grade, density 0.996 g / mL, specific volume 9.65 mL (approximately 9.61 g), is the core component of solution A; Anhydrous ethanol (EtOH): AR grade, density 0.789 g / mL, specific volume 37.52 mL (approximately 29.60 g), of which 30.02 mL is added to solution A and 7.5 mL to solution B, serving as the dispersion medium; Glacial acetic acid (HAc): AR grade, density 1.049 g / mL, specific volume 12.51 mL (approximately 13.12 g), is the chelating agent in solution A; Lanthanum nitrate solution: concentration 1.05 mol / L (prepared with La(NO3)3·6H2O), specific volume 0.21 mL (containing La(NO3)3·6H2O) 0.096g), serving as the doping source for solution B; distilled water (H2O): deionized water, specifically 10.0mL (10.0g), used as the hydrolysis medium; 1-ethyl-3-methylimidazolium tetrafluoroborate (IL): AR grade, density 1.29g / mL, specifically 0.53mL (approximately 0.684g), used as a crystal form stabilizer.

[0046] Preparation method S1. Preparation of Solution A: Add 9.65 mL of tetrabutyl titanate to 30.02 mL of anhydrous ethanol, stir until homogeneous, then add 12.51 mL of glacial acetic acid, and continue magnetic stirring for 10 min to obtain a homogeneous and transparent Solution A (TBOT to anhydrous ethanol volume ratio 1:3.1, glacial acetic acid to anhydrous ethanol volume ratio 1.25:3); S2. Preparation of Solution B: Add 0.21 mL of 1.05 mol / L lanthanum nitrate solution to 7.5 mL of anhydrous ethanol, stir until dissolved, then add 10.0 mL of distilled water and 0.53 mL of ionic liquid sequentially, and continue stirring for 15 min to obtain a homogeneous Solution B (anhydrous ethanol to distilled water volume ratio 7.5:10, lanthanum nitrate solution to distilled water volume ratio 1:10, glacial acetic acid ... The volume ratio of ionic liquid to distilled water is 2.1:100 (volume ratio of ionic liquid to distilled water is 5.3:100). S3, Sol-gel formation: Solution B is slowly added dropwise to solution A at a rate of 0.02 mL / s (volume ratio of solution A to solution B is 2.98:1). After the addition is complete, the mixture is continuously magnetically stirred for 4 hours to form a uniform and transparent gel. S4, Post-treatment: After the gel is allowed to stand for 24 hours, it is placed in an electric thermostatic drying oven and dried at 100℃ for 2 hours. After cooling to room temperature, it is ground to obtain coarse material. The coarse material is placed in a muffle furnace and calcined at 603℃ for 1.9 hours. After naturally cooling to room temperature, a stable crystal form of photocatalyst (La doping ratio 0.128%, ionic liquid addition amount 12.8 mL / mg) is obtained.

[0047] Example 5 raw material components Tetrabutyl titanate (TBOT): AR grade, density 0.996 g / mL, specific volume 10.52 mL (approximately 10.48 g), is the core component of solution A; Anhydrous ethanol (EtOH): AR grade, density 0.789 g / mL, specific volume 37.01 mL (approximately 29.20 g), of which 30.51 mL is added to solution A and 6.5 mL to solution B, serving as the dispersion medium; Glacial acetic acid (HAc): AR grade, density 1.049 g / mL, specific volume 11.70 mL (approximately 12.27 g), is the chelating agent in solution A; Lanthanum nitrate solution: concentration 0.95 mol / L (prepared with La(NO3)3·6H2O), specific volume 0.19 mL (containing La(NO3)3·6H2O) 0.079 g), serving as the doping source for solution B; distilled water (H2O): deionized water, specifically 10.0 mL (10.0 g), used as the hydrolysis medium; 1-ethyl-3-methylimidazolium tetrafluoroborate (IL): AR grade, density 1.29 g / mL, specifically 0.495 mL (approximately 0.639 g), serving as a crystal form stabilizer, the stabilizer including the components listed in parts by weight.

[0048] Preparation method S1. Preparation of Solution A: Add 10.52 mL of tetrabutyl titanate to 30.51 mL of anhydrous ethanol, stir until homogeneous, then add 11.70 mL of glacial acetic acid, and continue magnetic stirring for 10 min to obtain a homogeneous and transparent solution A (TBOT to anhydrous ethanol volume ratio 1:2.9, glacial acetic acid to anhydrous ethanol volume ratio 1.15:3); S2. Preparation of Solution B: Add 0.19 mL of 0.95 mol / L lanthanum nitrate solution to 6.5 mL of anhydrous ethanol, stir to dissolve, then add 10.0 mL of glacial acetic acid to anhydrous ethanol. S3, Sol-gel formation: Solution B was slowly added dropwise to Solution A at a rate of 0.02 mL / s (volume ratio of Solution A to Solution B: 2.92:1). After the addition was complete, the mixture was magnetically stirred for 4 hours to form a uniform and transparent gel. S4, Post-treatment: After the gel was allowed to stand for 24 hours, it was placed in an electric thermostatic drying oven and dried at 100℃ for 2 hours. After cooling to room temperature, it was ground to obtain a coarse material. The coarse material was placed in a muffle furnace and calcined at 598℃ for 2.1 hours. After natural cooling to room temperature, a stable crystal form of photocatalyst (La doping ratio 0.123%, ionic liquid addition amount 12.3 mL / mg) was obtained.

[0049] Comparative Example 1 Without adding ionic liquid, the remaining steps are the same as in Example 1.

[0050] Comparative Example 2 Add 0.25 mL of ionic liquid, and follow the same steps as in Example 1.

[0051] Comparative Example 3 Add 0.75 mL of ionic liquid, and follow the same steps as in Example 1.

[0052] Comparative Example 4 Add 1.00 mL of ionic liquid, and follow the same steps as in Example 1.

[0053] Comparative Example 5 Without adding lanthanum nitrate solution, the remaining steps are the same as in Example 1.

[0054] Comparative Example 6 Add 0.1 mL of lanthanum nitrate solution, and follow the same steps as in Example 1. The resulting catalyst has a La doping ratio of approximately 0.0625%.

[0055] Comparative Example 7 Add 0.3 mL of lanthanum nitrate solution, and follow the same steps as in Example 1. The resulting catalyst has a La doping ratio of approximately 0.1875%.

[0056] Comparative Example 8 Add 0.4 mL of lanthanum nitrate solution, and follow the same steps as in Example 1. The resulting catalyst has a La doping ratio of approximately 0.25%.

[0057] Comparative Example 9 Add 0.8 mL of lanthanum nitrate solution, and follow the same steps as in Example 1. The La doping ratio in the obtained catalyst is about 0.5%.

[0058] Comparative Example 10 The calcination temperature was changed to 300℃, and the remaining steps were the same as in Example 1.

[0059] Comparative Example 11 The calcination temperature was changed to 400℃, and the remaining steps were the same as in Example 1.

[0060] Comparative Example 12 The calcination temperature was changed to 500℃, and the remaining steps were the same as in Example 1.

[0061] Comparative Example 13 The calcination temperature was changed to 700℃, and the remaining steps were the same as in Example 1.

[0062] Comparative Example 14 The calcination temperature was changed to 800℃, and the remaining steps were the same as in Example 1.

[0063] Comparative Example 15 Nano-titanium dioxide is used directly as a catalyst.

[0064] Experimental Example 1 The catalysts prepared in Example 1 and Comparative Example 1 were characterized using a Phenom LE field emission scanning electron microscope (PESEM) manufactured by Phenom GmbH, Netherlands. The results obtained at 75,000x magnification are as follows: Figure 1 As shown, where Figure 1 a is a scanning electron microscope image of the catalyst prepared in Comparative Example 1. Figure 1 b is a scanning electron microscope image of the catalyst prepared in Example 1. Figure 1 In a, the La-doped titanium dioxide photocatalyst particles are bulky, while Figure 1 The La-doped titanium dioxide photocatalyst assisted by ionic liquid in b has smaller particles and a more uniform particle size.

[0065] Experimental Example 2 The photocatalysts prepared in Example 1 and Comparative Example 1 were characterized using a TD-3000 X-ray diffractometer manufactured by Liaoning Dandong Tongda Instrument Factory. The results are as follows: Figure 2 As shown, where Figure 2 (a) is the X-ray diffraction pattern of the catalyst prepared in Example 1, and (b) is the X-ray diffraction pattern of the catalyst prepared in Comparative Example 1. A comparison of (a) and (b) shows that ionic liquid assistance did not cause a significant shift in the diffraction peaks; however, the peaks assisted by the ionic liquid were sharper. In the X-ray diffraction spectra of both photocatalysts, a strong peak appeared at 2θ = 25.92°, a characteristic peak of anatase titanium dioxide. Diffraction peaks also appeared at 2θ = 37.96°, 48.48°, 55.08°, and 63.32°, which are essentially the same as the X-ray diffraction peaks of standard anatase titanium dioxide crystals at 2θ = 25.5°, 36.4°, and 48.1°.

[0066] Experimental Example 3 The catalysts prepared in Example 1 and Comparative Example 1 were characterized using an HCT-2 differential thermal-thermogravimetric analyzer manufactured by Beijing Hengjiu Scientific Instrument Factory. The results are as follows: Figure 3 As shown, a is the FTIR characterization pattern of the catalyst prepared in Example 1, and b is the FTIR characterization pattern of the catalyst prepared in Comparative Example 1; according to Figure 3 The results show that 478 cm appears in Figure a but not in Figure b. -1 and 1080 cm -1 The peak at that position corresponds to the stretching vibrations of the Ti-O-Ti and CN bonds in 1-ethyl-3-methylimidazolium tetrafluoroborate. The characteristic peaks in the infrared spectrum show that 1-ethyl-3-methylimidazolium tetrafluoroborate has been successfully doped into TiO2.

[0067] Test Example 4 The photocatalysts prepared in Example 1 and Comparative Example 1 were characterized using an HCT-2 differential thermal-thermogravimetric analyzer manufactured by Beijing Hengjiu Scientific Instrument Factory. The results are as follows: Figure 4 As shown in the figure. The two small endothermic peaks at 61℃ and 87℃ shown in Figure (a) are formed by the volatilization of water, ethanol, and glacial acetic acid bound to and remaining in the photocatalyst; the endothermic peak at 336.69℃ should be generated by the volatilization of the ionic liquid, and the exothermic peak at 350℃~400℃ is caused by the decomposition of the ionic liquid. The exothermic peak at 350℃~400℃ is the transformation peak of the amorphous structure of titanium dioxide to the anatase crystal form of titanium dioxide. The thermogravimetric analysis line in Figure (b) shows that the weight loss of the ionic liquid-assisted La-doped titanium dioxide photocatalyst only reaches a stable level at around 400℃. It can be seen that the mass loss is mainly due to the mass loss of physically adsorbed water on the titanium dioxide surface, the mass loss of bound water in titanium dioxide, the mass loss of ionic liquid volatilization, and the mass loss of ionic liquid decomposition.

[0068] Experimental Example 5 A 4 mg / L Rhodamine B solution was placed in a 100 mL beaker. 40 mg of an ionic liquid-assisted La-doped titanium dioxide photocatalyst was added to the Rhodamine B solution. The suspension was then placed under a UV lamp, and the absorbance was measured every 10 minutes using a 722N visible spectrophotometer. The absorbance over a specific time period was then determined, and the degradation rate was calculated using the formula.

[0069] Formula: Degradation rate (%) = ×100%, where A0 is the absorbance of the initial solution and A is the absorbance of the solution after degradation.

[0070] Based on the above-mentioned amounts of Rhodamine B solution and catalyst, the catalysts prepared in Comparative Examples 1-4 and Example 1 were added respectively. Then, degradation experiments were carried out on Rhodamine B solution. The experimental data of Rhodamine B solution degradation assisted by ionic liquid-assisted La-doped TiO2 photocatalyst were recorded at different ionic liquid contents of 0 mL, 0.25 mL, 0.5 mL, 0.75 mL and 1 mL, and the degradation rate at each ionic liquid content was calculated.

[0071] The results are as follows Figure 5 As shown, under ultraviolet light, the degradation rate of La-doped titanium dioxide photocatalysts assisted by different ionic liquid contents varies. With increasing ionic liquid content, the degradation rate reaches 84.32% at 0.5 mL, indicating the optimal degradation effect. Increasing the ionic liquid content accelerates the degradation of La... 3+The increased entry rate of the ionic liquid into the titanium dioxide lattice improves the degradation rate of the solution by the ionic liquid-assisted La-doped titanium dioxide photocatalyst. On the other hand, the addition of the ionic liquid can suppress the formation of the rutile phase. When the ionic liquid content increases to a certain level, the excess ionic liquid inhibits the growth of titanium dioxide crystal nuclei, leading to a decrease in the degradation rate.

[0072] Experimental Example 6 Based on the amount of Rhodamine B solution and catalyst used in Experimental Example 5, the catalysts prepared in Example 1 and Comparative Examples 5-9 were added respectively. Then, the Rhodamine B solution was subjected to photocatalytic degradation experiments, and the data were recorded to calculate the final degradation rate.

[0073] The results are as follows Figure 6 As shown, when the La doping ratio reaches 0.125%, the degradation rate reaches 84.32%. When it is less than 0.125%, La... 3+ The amount of La entering the titanium dioxide lattice is very small, resulting in a low degradation rate. Increasing the La doping ratio reduces the likelihood of photogenerated electron-hole pairs in the titanium dioxide lattice. The optimal degradation rate is achieved at a La doping ratio of 0.125%. When the La doping ratio is greater than 0.125%, the amount of La entering the titanium dioxide lattice increases. 3+ It is already saturated, while the La on the surface of titanium dioxide... 3+ By binding La(NO3)3 to the surface of titanium dioxide, the degradation performance of the photocatalyst was inhibited.

[0074] Experimental Example 7 Based on the amount of Rhodamine B solution and catalyst used in Experimental Example 5, catalysts prepared in Comparative Examples 10-14 and Example 1 were added respectively. Then, photocatalytic degradation experiments were conducted on Rhodamine B solution. Experimental data on the degradation of Rhodamine B solution by ionic liquid-assisted La-doped TiO2 photocatalyst under different calcination temperatures of 300℃, 400℃, 500℃, 600℃, 700℃, and 800℃ were recorded, and the degradation rate at each temperature was calculated.

[0075] The results are as follows Figure 7 As shown, under ultraviolet light, the degradation rate of the solution by the ionic liquid-assisted La-doped titanium dioxide photocatalyst calcined at different temperatures varies. The figure shows that the degradation rate reaches its highest point (92.38%) at a calcination temperature of 600℃. XRD patterns indicate that the anatase nuclei in the ionic liquid-assisted La-doped titanium dioxide photocatalyst tend to be more complete at 600℃. When the temperature increases above 600℃, the titanium dioxide in the photocatalyst transforms from the anatase phase to the rutile phase, inhibiting the degradation performance of the photocatalyst.

[0076] Experimental Example 8 At room temperature, the catalyst prepared in Example 1 was added to 100 mL of Rhodamine B solution at amounts of 30 mg, 35 mg, 40 mg, 45 mg, and 50 mg, respectively. Then, photocatalytic degradation experiments were carried out on the Rhodamine B solution. The experimental data of Rhodamine B solution degradation by ionic liquid-assisted La-doped TiO2 photocatalyst under different catalyst dosages of 30 mg, 35 mg, 40 mg, 45 mg, and 50 mg were recorded, and the degradation rate at each dosage was calculated.

[0077] The results are as follows Figure 8 As shown, the degradation rate reached its maximum of 92.38% when the dosage reached 40 mg, and the degradation rate gradually decreased with further increases in dosage. If the amount of catalyst is too large, the catalyst in the solution will aggregate, reducing the surface area of ​​the reaction contact; on the other hand, if there is too much photocatalyst, the free radicals generated in the reaction system will be saturated, and the remaining catalyst in the solution will affect the incident light in the spectrophotometer, scattering and shielding the incident light, leading to a decrease in the degradation rate.

[0078] Experimental Example 9 Rhodamine B solution in 100 mL beakers at room temperature was then mixed with 35 mg, 40 mg, and 45 mg of the photocatalyst prepared in Example 1, respectively. The mixture was then irradiated with a UV lamp for 1.5 h to degrade the solution. The absorbance of the solution was recorded every 10 min, and the degradation rate at each time point was calculated.

[0079] The results are as follows Figure 9 As shown, under UV light, the degradation rate of Rhodamine B solution by 0.5 mL ionic liquid-assisted La-doped titanium dioxide photocatalyst calcined at 600℃ with different catalyst dosages increased with time and then stabilized after a certain period. The increase in degradation rate was particularly significant in the first 10 min; the degradation rate gradually increased from 10 to 80 min; at 80 min, the degradation rate reached a certain value and then stabilized. After 80 min, the reaction was complete, and the absorbance of the solution stabilized with minimal fluctuation.

[0080] Experimental Example 10 A 4 mg / L Rhodamine B solution was placed in a 100 mL beaker. 40 mg of the photocatalysts prepared in Examples 1, 1, and 15 were added to the Rhodamine B solution, respectively. The suspensions were then placed under a UV lamp, and the absorbance was measured using a 722N visible spectrophotometer after 120 minutes. The degradation rate was then calculated using the formula.

[0081] Formula: Degradation rate (%) = ×100%, where A0 is the absorbance of the initial solution and A is the absorbance of the solution after degradation.

[0082] The results are shown in Table 1.

[0083] Table 1 Comparison of photocatalytic performance of different catalysts According to the results in Table 1, in terms of photocatalytic effect: ionic liquid-assisted La-doped titanium dioxide > La-doped titanium dioxide > nano-titanium dioxide. The ionic liquid assists in the more efficient entry of La into the defect sites on the titanium dioxide surface. La doping can alter the crystallinity of TiO2 or introduce defect sites on the surface, acting as traps for electrons or holes, thus increasing its effective time. It can also act as recombination centers, accelerating the reaction process. Furthermore, the ionic liquid allows the catalyst to maintain its activity for a longer time than a single catalyst, thereby enhancing the photocatalytic ability of the photocatalyst.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A photocatalyst with a stable crystal form, characterized in that: The present invention relates to an ionic liquid-assisted La-doped TiO2 photocatalyst, wherein the ionic liquid is a 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid, the content of the 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid in the ionic liquid-assisted La-doped TiO2 photocatalyst is 12-13 mL / mg, and the La doping ratio is 0.12-0.13%.

2. The application of a photocatalyst with a stable crystal form as described in claim 1 in the degradation of wastewater containing Rhodamine B.

3. The application according to claim 2, characterized in that: Includes the following steps: A1. The ionic liquid-assisted La-doped TiO2 photocatalyst is added to the Rhodamine B solution, wherein the mass ratio of the ionic liquid-assisted La-doped TiO2 photocatalyst to the Rhodamine B in the Rhodamine B solution is (99~101):

1. A2. Then, apply light for at least 80 minutes to complete the degradation of Rhodamine B.

4. A method for preparing a photocatalyst with a stable crystal form as described in claim 1, characterized in that: Includes the following steps: S1. Add tetrabutyl titanate to anhydrous ethanol, then add glacial acetic acid and stir well to obtain solution A for later use. S2. Add La(NO3)3 solution to anhydrous ethanol, then add distilled water and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid in sequence to obtain solution B. S3. Add liquid B dropwise to liquid A and stir until homogeneous to obtain a gel; S4. After standing, dry and cool to obtain coarse material. Grind the coarse material and calcine it to room temperature to obtain the ion liquid-assisted La-doped TiO2 photocatalyst.

5. The method for preparing a stable crystalline photocatalyst according to claim 4, characterized in that: The volume ratio of liquid A to liquid B is (2.9-3):

1.

6. The method for preparing a stable crystal form photocatalyst according to claim 4, characterized in that: In S4, the calcination temperature is 595-605℃.

7. The method for preparing a stable crystal form photocatalyst according to claim 6, characterized in that: In S4, the calcination time is 1.8-2.2 h.

8. The method for preparing a stable crystal form photocatalyst according to claim 4, characterized in that: The concentration of the La(NO3)3 solution is 0.9-1.1 mol / L.

9. The method for preparing a stable crystal form photocatalyst according to claim 4, characterized in that: In solution A, the volume ratio of tetrabutyl titanate to anhydrous ethanol is 1:(2.8-3.2), and the volume ratio of glacial acetic acid to anhydrous ethanol is (1.1-1.3):

3.

10. The method for preparing a stable crystalline photocatalyst according to claim 9, characterized in that: In solution B, the volume ratio of anhydrous ethanol to distilled water is (6-8):10, the volume ratio of La(NO3)3 solution to distilled water is (1.8-2.2):100, and the volume ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid to distilled water is (4.8-5.5):100.

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