A zinc-doped modified CaSn(OH)6 photocatalyst, a preparation method and application thereof

Abstract

This invention discloses a zinc-doped modified CaSn(OH)6 photocatalyst, its preparation method, and its application. The preparation method includes the following steps: (1) under room temperature conditions, Sn-containing... 4+ The reaction raw materials contain OH ‑ (1) Stir and mix the reaction raw materials and deionized water evenly; (2) Add Ca to the system of step (1). 2+ (2) Add zinc acetate powder to the white solution and stir for 3-5 hours to mix evenly at a stirring speed of 600-800 r / min to form a mixed liquid; (3) Let the mixed liquid stand at room temperature for 8-15 hours to precipitate the precipitate, wash the precipitate with deionized water and ethanol in sequence, dry it, grind it, and obtain zinc-doped modified CaSn(OH)6 photocatalyst. The preparation method of the zinc-doped modified CaSn(OH)6 photocatalyst is simple, and the prepared photocatalyst can effectively remove toluene, with high degradation activity and good stability.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, specifically to a zinc-doped modified CaSn(OH)6 photocatalyst, its preparation method, and its application. Background Technology

[0002] TiO2 plays a crucial role as a typical photocatalyst in removing environmental pollutants. However, when degrading volatile organic compounds (VOCs) in the environment, it is easily poisoned by intermediate products, leading to sample deactivation. Therefore, developing a novel photocatalyst for degrading benzene compounds is an important research topic to avoid poisoning the photocatalyst and enable its recycling. Among these photocatalytic materials, CaSn(OH)6 exhibits significant advantages due to the presence of numerous hydroxyl groups on its surface, which effectively promote the generation of hydroxyl free radicals. This provides more active species to facilitate the photocatalytic reaction, and hydroxyl groups are the main active free radicals for ring opening in aromatic hydrocarbons. Furthermore, unlike easily corroded sulfides and halides (which are susceptible to photocorrosion), the photostability of hydroxides is reasonably predictable. Moreover, CaSn(OH)6 catalysts are simple to prepare, using chemical precipitation or a one-step hydrothermal method. They can ultimately mineralize recalcitrant benzene compounds into harmless CO2 and H2O.

[0003] However, CaSn(OH)6 suffers from drawbacks such as rapid recombination of photogenerated carriers, small specific surface area, and few surface sites, resulting in low photocatalytic activity. Furthermore, the stable benzene ring structure and non-oxidizable C(sp) group in toluene further contribute to its low photocatalytic activity. 3The formation of the -H bond requires overcoming a considerable reaction energy and necessitates strong and abundant oxidation by active free radicals. Therefore, to improve photocatalytic activity, it is necessary to find effective modification strategies to enable CaSn(OH)6 to generate more active free radicals and multiple active sites for adsorbing and activating target molecules. Research reports indicate that in the toluene ring-opening process, the oxidation pathway of the methyl group before ring-opening in the benzene ring is: toluene → benzyl alcohol → benzaldehyde → benzoic acid. Furthermore, the reaction energy barriers for all four possible ring-opening processes on CaSn(OH)6 decrease at the defect surface. In other words, the presence of surface defects lowers the activation energy of the ring-opening reaction during the photocatalytic degradation of toluene. Therefore, introducing defects is an effective strategy to improve photocatalytic activity. Elemental doping has been found to be one of the simplest methods for introducing defects and providing trap centers or complex centers for electron or hydrogen ion capture. Doped atoms play a role in electron aggregation, constructing directional electron transfer channels and promoting the photocatalytic removal of volatile organic compounds. This is a novel strategy for effectively quenching charge recombination and promoting electron transfer. Elemental doping has a certain impact on the photoelectronic structure, thus enhancing the activity of pollutant degradation and thereby improving photocatalytic performance. Therefore, developing a stable and highly active doped CaSn(OH)6 photocatalyst would be of great significance. Summary of the Invention

[0004] Therefore, this invention aims to overcome the problem of O2 adsorption and activation difficulties in existing technologies by providing a zinc-doped modified CaSn(OH)6 photocatalyst and its preparation method. The preparation method of the zinc-doped modified CaSn(OH)6 photocatalyst of this invention is simple, can be performed at room temperature, and the prepared photocatalyst can effectively remove toluene, exhibiting high degradation activity and good stability.

[0005] Another object of the present invention is to provide the application of the zinc-doped modified CaSn(OH)6 photocatalyst.

[0006] The technical solution is as follows:

[0007] A method for preparing a zinc-doped modified CaSn(OH)6 photocatalyst includes the following steps:

[0008] (1) Under normal temperature conditions, Sn-containing 4+ The reaction raw materials, reaction raw materials containing OH-, and deionized water are stirred and mixed evenly.

[0009] (2) Add Ca to the system of step (1). 2+ The solution was stirred and mixed thoroughly to obtain a white solution;

[0010] (3) Add zinc acetate powder to the white solution and stir for 3-5 hours to mix thoroughly. The stirring speed is 600-800 r / min to form a mixture. The molar amount of zinc acetate powder is related to the amount of Ca. 2+ The molar ratio is (0.49~1.48):1;

[0011] (4) The mixture was allowed to stand at room temperature for 8-15 hours to precipitate, and the precipitate was washed with deionized water and ethanol in sequence, dried, and ground to obtain zinc-doped modified CaSn(OH)6 photocatalyst.

[0012] In one embodiment, the zinc acetate powder and Ca 2+ The molar ratio is 0.98:1.

[0013] In one embodiment, the Ca 2+ Sn 4+ The molar ratio of OH- is (0.5~1.5):(0.5~1.5):(5.5~6.5).

[0014] In one embodiment, the Ca 2+ Sn 4+ The molar ratio of OH- is 1.08:1:6.

[0015] In one embodiment, the Sn-containing 4+ The reaction raw materials, including those containing OH-, are SnCl4·5H2O solid and NaOH solid, respectively. The reaction raw material containing Ca... 2+ The solution is an aqueous solution of CaCl2.

[0016] In one embodiment, the zinc-doped modified CaSn(OH)6 photocatalyst has a particle size of 0.3-0.6 μm.

[0017] The zinc-doped modified CaSn(OH)6 photocatalyst prepared by the above preparation method has a photocatalytic activity of greater than 84% for toluene within 60 min and greater than 80% within 360 min.

[0018] In one embodiment, the zinc-doped modified CaSn(OH)6 photocatalyst exhibits 100% photocatalytic activity against toluene within 60 min and greater than 98% photocatalytic activity within 360 min.

[0019] Application of the zinc-doped modified CaSn(OH)6 photocatalyst in the removal of toluene contaminants.

[0020] The beneficial effects of this invention are as follows: This invention uses a room-temperature precipitation synthesis method to prepare a zinc-doped modified CaSn(OH)6 photocatalyst. Due to the introduction of zinc, the structure of CaSn(OH)6 changes, and electrons accumulate on the surface hydroxyl groups. These electron-rich hydroxyl groups capture photogenerated holes to form ·OH, which is the main active free radical for ring opening in aromatic hydrocarbons. Furthermore, O2 molecules are reduced to ·O2- by hydroxyl defects, contributing to the continuous and efficient photocatalytic mineralization of toluene. The free radical generation rate is significantly improved, effectively increasing the toluene degradation efficiency, and the catalytic activity exhibits good stability, showing broad application prospects in the field of environmental pollution control. Attached Figure Description

[0021] Figure 1 The graph shows the photocatalytic activity test results of the products obtained in Comparative Examples 1, 2 and 1-3 under ultraviolet light irradiation for the removal of toluene.

[0022] Figure 2 The plot shows the activity and stability test results of the product obtained in Comparative Example 1 for photocatalytic removal of toluene contaminants within 290 min.

[0023] Figure 3 The graph shows the activity and stability test of the product obtained in Example 2 for photocatalytic removal of toluene contaminants within 360 min.

[0024] Figure 4 X-ray diffraction patterns of zinc-doped modified CaSn(OH)6 prepared in Comparative Examples 1, 2 and 1-3.

[0025] Figure 5 The images are scanning electron microscope (SEM) images of the products obtained in Comparative Example 1 and Example 2.

[0026] Figure 6 The XPS high-resolution Zn 2p spectra are for Comparative Example 1 and Example 2.

[0027] Figure 7 The XPS high-resolution Ca 2p spectra are for Comparative Example 1 and Example 2.

[0028] Figure 8 High-resolution Sn 3d spectra of Comparative Example 1 and Example 2 are obtained using XPS.

[0029] Figure 9 The XPS high-resolution O1s 2p spectrum is shown in Example 2.

[0030] Figure 10 The images show the electron paramagnetic resonance (EPR) images of the products obtained in Comparative Example 1 and Example 2.

[0031] Figure 11 The images show the electron paramagnetic resonance (EPR) images of the products obtained in Comparative Example 1 and Example 2. Detailed Implementation

[0032] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate the following embodiments, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; it is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0033] In a first aspect, the present invention provides a method for preparing a zinc-doped modified CaSn(OH)6 photocatalyst, comprising the following steps:

[0034] (1) Under normal temperature conditions, Sn-containing 4+ The reaction raw materials contain OH - The reaction raw materials and deionized water are stirred and mixed evenly.

[0035] (2) Add Ca to the system of step (1). 2+ The solution was stirred and mixed thoroughly to obtain a white solution;

[0036] (3) Add zinc acetate powder to the white solution and stir for 3-5 hours to mix thoroughly. The stirring speed is 600-800 r / min to form a mixture. The molar amount of zinc acetate powder is related to the amount of Ca. 2+ The molar ratio is (0.49~1.48):1;

[0037] (4) The mixture was allowed to stand at room temperature for 8-15 hours to precipitate, and the precipitate was washed with deionized water and ethanol in sequence, dried, and ground to obtain zinc-doped modified CaSn(OH)6 photocatalyst.

[0038] The reaction mechanism of this invention: Based on the "crystallization-dissolution-crystallization" mechanism, this invention involves a reaction that occurs during chemical precipitation synthesis: Ca 2+ +Sn 4+ +6OH - +Zn 4+→CaSn(OH)6 (containing zinc atoms). The chemical precipitation strategy allows for complete reaction of the reactants, effectively incorporating zinc atoms into the CaSn(OH)6 lattice to obtain a unique crystalline material. The zinc-doped modified CaSn(OH)6 photocatalyst prepared by this method contains only one phase. Due to the introduction of zinc, the structure of CaSn(OH)6 changes, forming Zn=O bonds on the CaSn(OH)6 crystal surface. Since oxygen is more electronegative than zinc ions, the electron cloud shifts towards the adsorbed oxygen on the surface. Therefore, there is a tendency for charge accumulation in zinc-doped modified CaSn(OH)6, with electrons enriched on the surface hydroxyl groups. After these electron-rich hydroxyl groups capture photogenerated holes to form ·OH, they break the chemical bonds with the metal cations, creating defects in their original positions. In the presence of H2O molecules, these surface hydroxyl defects can be regenerated and replenished, ultimately forming a dynamic process of defect generation, annihilation, and regeneration. This process endows zinc-doped modified CaSn(OH)6 with good charge transfer ability, excellent photogenerated carrier separation efficiency, high catalytic oxidation activity and stability, which helps to provide the basic conditions for the efficient preparation of zinc-doped modified CaSn(OH)6 photocatalysts, so as to successfully obtain high-yield and high-activity zinc-doped modified CaSn(OH)6 catalysts with multiple active sites.

[0039] In one embodiment, the zinc acetate powder and Ca 2+ The molar ratio is 0.98:1. Choosing an appropriate amount of zinc acetate can avoid waste while effectively ensuring that the final zinc-doped modified CaSn(OH)6 catalyst exhibits high catalytic activity against toluene. If too little zinc acetate is added, zinc will not be incorporated; if too much is added, the crystallinity of CaSn(OH)6 will decrease, damaging the crystal structure and reducing its activity against toluene.

[0040] In one embodiment, the Ca 2+ Sn 4+ OH - The molar ratio is (0.5–1.5):(0.5–1.5):(5.5–6.5). More specifically, the Ca... 2+ Sn 4+ OH - The molar ratio is 1.08:1:6.

[0041] In one embodiment, the Sn-containing 4+ The reaction raw materials contain OH - The reaction raw materials are SnCl4·5H2O and NaOH solid, respectively, and the substance containing Ca... 2+ The solution is an aqueous solution of CaCl2.

[0042] In the conical flask, water acts as a medium, facilitating the rapid dissolution of SnCl₄·5H₂O, CaCl₂, NaOH, and (CH₃COO)₂Zn, thus forming a solution containing a large amount of Sn. 4+ Ca 2+ OH - Zn 2+ A mixed solution of ions, followed by Ca... 2+ +Sn 4+ +6OH - +Zn 2+ →CaSn(OH)6 (containing zinc element) is synthesized from CaSn(OH)6 (containing zinc element).

[0043] In one embodiment, in step (1), the stirring time is 5 to 10 minutes and the stirring speed is 600 to 800 r / min.

[0044] In one embodiment, in step (2), the stirring time is 0.5 to 2 minutes and the stirring speed is 600 to 800 r / min.

[0045] In one embodiment, the stirring temperature is set to 25°C in steps (1) to (3).

[0046] In one embodiment, in step (4), a chemical precipitation reaction is carried out at room temperature for 12 hours.

[0047] In one embodiment, in step (4), the precipitate is washed three times each with deionized water and ethanol.

[0048] The present invention will be further described below with reference to specific embodiments.

[0049] Example 1

[0050] A zinc-doped modified CaSn(OH)6 photocatalyst, the preparation method of which is as follows:

[0051] (1) Set the variable temperature magnetic stirrer to the target temperature of 25℃, pour 1.2g NaOH solid, 1.75g ​​SnCl4·5H2O solid and 200ml deionized water into the conical flask, place the conical flask on the variable temperature magnetic stirrer and stir to form solution A.

[0052] (2) Weigh 0.6g CaCl2 and dissolve it in 20ml of deionized water to form solution B. Add solution B dropwise to solution A. The new solution is labeled C, and a white solution is obtained.

[0053] (3) After one minute, add 0.488 g of zinc acetate to the system in step (2), and continue stirring for 4 hours to mix evenly. The stirring speed is 600 r / min to obtain the mixture.

[0054] (4) Transfer the mixture to room temperature and darkness, let it stand for 12 hours to obtain precipitate, wash the precipitate three times with deionized water and three times with ethanol, dry it at 60°C for 12 hours, and then grind it to a particle size of 0.3-0.6 μm to obtain zinc-doped modified CaSn(OH)6 photocatalyst powder.

[0055] Example 2

[0056] A zinc-doped modified CaSn(OH)6 photocatalyst, the preparation method of which is as follows:

[0057] (1) Set the variable temperature magnetic stirrer to the target temperature of 25℃, pour 1.2g NaOH solid, 1.75g ​​SnCl4·5H2O solid and 200ml deionized water into the conical flask, place the conical flask on the variable temperature magnetic stirrer and stir to form solution A.

[0058] (2) Weigh 0.6g CaCl2 and dissolve it in 20ml of deionized water to form solution B. Add solution B dropwise to solution A. The new solution is labeled C, and a white solution is obtained.

[0059] (3) After one minute, add 0.976 g of zinc acetate to the system in step (2), and continue stirring for 4 hours to mix evenly. The stirring speed is 600 r / min to obtain the mixture.

[0060] (4) Transfer the mixture to room temperature and darkness, let it stand for 12 hours to obtain precipitate, wash the precipitate three times with deionized water and three times with ethanol, dry it at 60°C for 12 hours, and then grind it to a particle size of 0.3-0.6 μm to obtain zinc-doped modified CaSn(OH)6 photocatalyst powder.

[0061] Example 3

[0062] A zinc-doped modified CaSn(OH)6 photocatalyst, the preparation method of which is as follows:

[0063] (1) Set the variable temperature magnetic stirrer to the target temperature of 25℃, pour 1.2g NaOH solid, 1.75g ​​SnCl4·5H2O solid and 200ml deionized water into the conical flask, place the conical flask on the variable temperature magnetic stirrer and stir to form solution A.

[0064] (2) Weigh 0.6g CaCl2 and dissolve it in 20ml of deionized water to form solution B. Add solution B dropwise to solution A. The new solution is labeled C, and a white solution is obtained.

[0065] (3) After one minute, add 1.464 g of zinc acetate to the system in step (2), and continue stirring for 4 hours to mix evenly. The stirring speed is 600 r / min to obtain the mixture.

[0066] (4) Transfer the mixture to room temperature and darkness, let it stand for 12 hours to obtain precipitate, wash the precipitate three times with deionized water and three times with ethanol, dry it at 60°C for 12 hours, and then grind it to a particle size of 0.3-0.6 μm to obtain zinc-doped modified CaSn(OH)6 photocatalyst powder.

[0067] Comparative Example 1

[0068] A zinc-doped modified CaSn(OH)6 photocatalyst, the preparation method of which is as follows:

[0069] (1) Set the variable temperature magnetic stirrer to the target temperature of 25℃, pour 1.2g NaOH solid, 1.75g ​​SnCl4·5H2O solid and 200ml deionized water into the conical flask, place the conical flask on the variable temperature magnetic stirrer and stir to form solution A.

[0070] (2) Weigh 0.6g CaCl2 and dissolve it in 20ml of deionized water to form solution B. Add solution B dropwise to solution A. The new solution is labeled C, and a white solution is obtained.

[0071] (3) Continue stirring for 4 hours to mix evenly, with a stirring speed of 600 r / min, to obtain a mixture;

[0072] (4) Transfer the mixture to room temperature and darkness, let it stand for 12 hours to obtain precipitate, wash the precipitate three times with deionized water and three times with ethanol, dry it at 60°C for 12 hours, and then grind it to a particle size of 0.3-0.6 μm to obtain CaSn(OH)6 photocatalyst powder.

[0073] Comparative Example 2

[0074] A zinc-doped modified CaSn(OH)6 photocatalyst, the preparation method of which is as follows:

[0075] (1) Set the variable temperature magnetic stirrer to the target temperature of 25℃, pour 1.2g NaOH solid, 1.75g ​​SnCl4·5H2O solid and 200ml deionized water into the conical flask, place the conical flask on the variable temperature magnetic stirrer and stir to form solution A.

[0076] (2) Weigh 0.6g CaCl2 and dissolve it in 20ml of deionized water to form solution B. Add solution B dropwise to solution A. The new solution is labeled C, and a white solution is obtained.

[0077] (3) After one minute, add 1.952 g of zinc acetate to the system in step (2), and continue stirring for 4 hours to mix evenly. The stirring speed is 600 r / min to obtain the mixture.

[0078] (4) Transfer the mixture to room temperature and darkness, let it stand for 12 hours to obtain precipitate, wash the precipitate three times with deionized water and three times with ethanol, dry it at 60°C for 12 hours, and then grind it to a particle size of 0.3-0.6 μm to obtain zinc-doped modified CaSn(OH)6 photocatalyst powder.

[0079] Multiple characterization experiments were conducted on the photocatalysts of Examples 1-3, Comparative Examples 1 and 2. The photocatalysts of Examples 1 to 3 can be abbreviated as CSOH-40, CSOH-80 and CSOH-120 in the experimental results, and the photocatalysts of Examples 1 and 2 can be abbreviated as CSOH and CSOH-160 in the experimental results.

[0080] 1. Photocatalytic activity and stability characterization experiments

[0081] The catalyst performance was evaluated by real-time monitoring of the instantaneous concentration of C7H8 at the ppm level in the reaction chamber using a photoacoustic spectroscopy instrument at room temperature. The specific procedure was as follows: four 0.1g samples were weighed onto a 40mm × 100mm rectangular frosted glass slide with rounded corners. The slides were uniformly dispersed with a small amount of alcohol and then dried in a constant-temperature drying oven at 60℃. After cooling to room temperature, the catalyst-loaded glass slides were placed in a 0.34L (200mm × 100mm × 17mm) rectangular continuous-flow reaction chamber. A layer of quartz glass was placed on top of the chamber, and the chamber was sealed (secured with screws to prevent leakage). A 300W commercial mercury lamp was used above the chamber as the ultraviolet light source for the photocatalytic reaction. The initial concentration of pollutants was adjusted by regulating the flow meter in the gas path, and the flow rate of the humidified air was set to 0.5L·min⁻¹. 1 The flow rate of dry air (0.4 L·min- 1 ) and the flow rate of pollutants (0.1 L·min- 1 The sum of these is 0.5 L·min⁻¹ 1 The diluted C7H8 pollutant gas was introduced into the reaction chamber. Under dark conditions, after the catalyst reached adsorption-desorption equilibrium, the lights were turned on to carry out the pollutant degradation reaction, and the toluene concentration in the reaction chamber was recorded using a photoacoustic spectrometer.

[0082] Figure 1 The diagram shows the photocatalytic activity of toluene in the experimental process. The degradation activities of Examples 1-3 were 87.50%, 100%, and 84.80%, respectively, while the degradation activities of Comparative Examples 1 and 2 were 42.30% and 47.70%, respectively. This indicates that doping CaSn(OH)6 with a certain proportion of zinc in some wide-bandgap semiconductors is more beneficial to toluene degradation performance, but the doping amount must be strictly controlled and cannot be excessive. Furthermore, the photocatalytic oxidation activity of toluene at 65 ppm in Examples 1-3 was superior to that in Comparative Examples 1 and 2.

[0083] In addition, the present invention also conducted stability tests on Example 2 and Comparative Example 1, and found that the zinc-doped modified CaSn(OH)6 photocatalyst of Example 2 was basically stable in its photoactivity with toluene within 360 min, maintaining a degradation rate of approximately 100%. This indicates that the photocatalytic performance of the catalyst prepared by incorporating zinc into CaSn(OH)6 catalyst through a room temperature static precipitation method is excellent and stable. Figure 2 The figure shows the stability test results for Comparative Example 1. Figure 3 The stability test results for Example 2 are shown. In Comparative Example 1, the degradation rate was approximately 0% after 290 min, while the CaSn(OH)6 photocatalyst in Example 2 maintained a 100% degradation rate within 360 min. Although stability tests were not conducted on Examples 1 and 3 in the experiment, based on the experimental trends, it is estimated that the degradation rates of Examples 1 and 3 will still be no less than 80% within 360 min.

[0084] 2. XRD characterization experiment

[0085] To verify the types of products obtained in Comparative Examples 1, 2 and 1-3, the present invention used a German Bruker D8 Advance X-ray diffractometer (Cu Kα, λ = 0.154 nm, operating voltage and current 40 kV and 40 mA, respectively) to perform XRD tests on each product.

[0086] like Figure 4 As shown, the XRD results indicate that the diffraction peaks at 18.90°, 21.87°, 31.13°, 34.88°, 36.64°, 38.43°, 44.59°, 50.25° and 55.36° of the products obtained in Examples 1-3 and Comparative Examples 1 and 2 correspond to the planes of CaSn(OH)6 (JCPDS 09-0030) (111), (200), (220), (310), (311), (222), (400), (420) and (422), respectively, and no other impurity peaks were found.

[0087] 3. Electron microscopy characterization experiment

[0088] The morphology of the samples from Example 2 and Comparative Example 1 was characterized using a JEOL Model JSM-6490 scanning electron microscope (Japan). Figure 5 As shown, it can be found that zinc doping modified CaSn(OH)6 affects the morphology of the cubic crystal of CaSn(OH)6, and the size also becomes smaller.

[0089] 4. XPS characterization experiment

[0090] like Figure 6As shown, the XPS high-resolution Zn 2p spectrum of Example 2 shows a zinc peak, while no zinc peak was detected in Comparative Example 1. Furthermore, the elemental full spectrum also indicates that Comparative Example 1 does not contain zinc, while Example 2 does, confirming that zinc has been incorporated into CaSn(OH)6. Figure 7 The XPS high-resolution Ca 2p spectrum shows that, in Example 2, Ca 2p is assigned at 350.72 eV and 347.18 eV, respectively. 1 / 2 and Ca 2p 2 / 3 Compared to Comparative Example 1, the peak position shifts to the right, indicating that the binding energy of Ca decreases due to electron loss. For example... Figure 8 As shown, Example 2 is assigned to Sn 3d 3 / 2 and Sn 3d 5 / 2 The peak position at that location is assigned to Sn 3d in Comparative Example 1. 3 / 2 and Sn 3d 5 / 2 The peak position did not shift. For example... Figure 9 The peak area and intensity of Comparative Example 1 at 532.58 eV of lattice state O are higher than those of Example 2 at 532.22 eV of lattice state O. However, the peak area and intensity of Comparative Example 1 at 529.67 eV of adsorbed state O are lower than those of Example 2 at 530.30 eV of adsorbed state O. This indicates that zinc doping converts more lattice oxygen into adsorbed oxygen, which is more readily activated and facilitates faster free radical generation. These results suggest that the adsorbed oxygen is located near Zn, implying that the introduction of zinc alters the structure of CaSn(OH)6, forming Zn=O bonds on the CaSn(OH)6 crystal surface. Since oxygen is more electronegative than zinc ions, the electron cloud shifts towards the adsorbed oxygen on the surface, resulting in a charge accumulation trend in Example 2, with electrons enriched on the surface hydroxyl groups.

[0091] 5. Electron paramagnetic resonance

[0092] like Figure 10 , 11 As shown, the intensity of superoxide radicals and hydroxyl radicals generated in Example 2 and Comparative Example 1 was higher in Example 2 than in Comparative Example 1 within 30 minutes, proving that Example 2 was more likely to promote the generation of superoxide radicals and hydroxyl radicals.

[0093] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a zinc-doped modified CaSn(OH)6 photocatalyst, characterized in that, Includes the following steps: (1) Under normal temperature conditions, Sn-containing 4+ The reaction raw materials contain OH - The reaction raw materials and deionized water are stirred and mixed evenly. (2) Add Ca to the system of step (1) 2+ The solution was stirred and mixed thoroughly to obtain a white solution; (3) Add zinc acetate powder to the white solution and stir for 3-5 hours to mix evenly. The stirring speed is 600-800 r / min to form a mixture. The molar amount of zinc acetate powder is related to the amount of Ca. 2+ The molar ratio is (0.49~1.48):1; (4) The mixture was allowed to stand at room temperature for 8-15 hours to precipitate. The precipitate was washed with deionized water and ethanol in sequence, dried, and ground to obtain zinc-doped modified CaSn(OH)6 photocatalyst.

2. The method for preparing the zinc-doped modified CaSn(OH)6 photocatalyst according to claim 1, characterized in that, Zinc acetate powder and Ca 2+ The molar ratio is 0.98:

1.

3. The method for preparing the zinc-doped modified CaSn(OH)6 photocatalyst according to claim 1, characterized in that, The Ca 2+ Sn 4+ OH - The molar ratio is (0.5~1.5):(0.5~1.5):(5.5~6.5).

4. The method for preparing the zinc-doped modified CaSn(OH)6 photocatalyst according to claim 3, characterized in that, The Ca 2+ Sn 4+ OH - The molar ratio is 1.08:1:

6.

5. The method for preparing the zinc-doped modified CaSn(OH)6 photocatalyst according to claim 1, characterized in that, The containing Sn 4+ The reaction raw materials contain OH - The reaction raw materials are SnCl4·5H2O solid and NaOH solid, respectively, and the substance containing Ca 2+ The solution is an aqueous solution of CaCl2.

6. A zinc-doped modified CaSn(OH)6 photocatalyst prepared by the preparation method according to any one of claims 1 to 5, characterized in that, The zinc-doped modified CaSn(OH)6 photocatalyst has a particle size of 0.3-0.6 μm.

7. The application of the zinc-doped modified CaSn(OH)6 photocatalyst according to claim 6 in the removal of toluene contaminants.

8. The application according to claim 7, characterized in that, The zinc-doped modified CaSn(OH)6 photocatalyst exhibits a photocatalytic activity of greater than 84% for toluene within 60 min, and a photocatalytic activity of greater than 80% within 360 min.

9. The application according to claim 7, characterized in that, The zinc-doped modified CaSn(OH)6 photocatalyst exhibits 100% photocatalytic activity for toluene within 60 min, and its photocatalytic activity is greater than 98% within 360 min.

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