A kind of InZrO x Carbon Nitride Catalysts, Their Preparation Methods and Applications

Abstract

This invention belongs to the field of oxytetracycline photocatalytic degradation technology, and particularly relates to an InZrO3-O4 ... x / Carbon nitride catalyst, its preparation method, and its application. The InZrO... x / Carbon nitride catalyst consists of carbon nitride, InZrO x A highly efficient ternary composite photocatalytic system was constructed by combining InZrO, and the InZrO content was further optimized. x The loading and In / Zr molar ratio design optimizes the band structure matching, while providing more abundant surface active sites, improving photocatalytic activity and enhancing catalyst stability. It is suitable for anhydrous, high-efficiency solar-driven degradation of oxytetracycline-containing materials and has the potential for large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of oxytetracycline photocatalytic degradation technology, and particularly relates to an InZrO3-O4 ... x / Carbon nitride catalysts, their preparation methods and applications. Background Technology

[0002] Oxytetracycline (OTC), a broad-spectrum antibiotic widely used in livestock and aquaculture, suffers from extensive use and improper discharge, resulting in widespread residues in natural water bodies and soil environments. OTC exhibits environmental persistence, bioaccumulation, and potential ecotoxicity, and can induce the generation and spread of resistance genes, posing a serious threat to ecosystems and human health. Therefore, developing efficient, economical, and environmentally friendly OTC removal technologies is crucial.

[0003] Photocatalysis technology has shown great potential in environmental remediation due to its advantages such as directly utilizing solar energy to drive pollutant degradation, simple operation, and no secondary pollution. Graphitic carbon nitride (g-C3N4), as a non-metallic, visible-light-responsive semiconductor photocatalyst, has been widely studied due to its good chemical stability, non-toxicity, ease of synthesis, and suitable band structure. However, pristine g-C3N4 has inherent defects such as small specific surface area, high photogenerated carrier recombination rate, and limited visible light utilization, which makes its photocatalytic activity difficult to meet the needs of practical applications.

[0004] To overcome the shortcomings of g-C3N4, researchers have modified it by combining it with metal oxides. Metal oxides can act as cocatalysts or construct heterojunctions, effectively promoting the separation and migration of photogenerated electron-hole pairs, expanding the photoresponse range, and potentially providing additional active sites. Various metal oxides (such as TiO2, ZnO, WO3, and Fe2O3) have been used to modify g-C3N4 to enhance its photocatalytic performance. However, finding novel metal oxide composite systems with higher synergistic effects, better stability, and controllable costs, especially for recalcitrant organic pollutants such as OTC, remains a current research hotspot and challenge. Summary of the Invention

[0005] To address the shortcomings of existing methods, this invention provides an InZrO x / Carbon nitride catalyst and its preparation method.

[0006] The InZrO x / Carbon nitride catalyst consists of carbon nitride, InZrO x Composed of composites; the InZrO x The quality is InZrO x / 2-8% of carbon nitride catalyst.

[0007] Furthermore, the InZrO x The molar ratio of In to Zr is 0.1 to 0.5.

[0008] Furthermore, the InZrO x The preparation method of carbon nitride catalyst includes the following steps:

[0009] (1) Dissolve indium salt and zirconium salt in deionized water, heat and stir until completely dissolved to obtain metal salt solution.

[0010] Furthermore, the indium salt is indium nitrate; the zirconium salt is zirconium nitrate;

[0011] Furthermore, the molar ratio of the indium salt to the zirconium salt is 0.1 to 0.5.

[0012] Furthermore, the heating and stirring temperature is 65–75°C;

[0013] (2) Prepare a concentration of 1–5 mol·L⁻¹ -1 Ammonia solution.

[0014] (3) Add carbon nitride to deionized water and sonicate for 10-40 minutes to obtain a dispersion.

[0015] Furthermore, the concentration of carbon nitride in the dispersion is 5–10 g / L.

[0016] (4) Under stirring conditions and at 70-85°C, the metal nitrate solution and ammonia solution are dripped into the dispersion to form a precipitate, and the pH of the reaction system is maintained at 7.5-8.0.

[0017] (5) Continue stirring for 1 hour, then age at 70-85°C for 5-8 hours, filter, wash, dry, and obtain powder.

[0018] (6) Place the powder in an inert atmosphere and calcine it at 500-550℃ for 3-6 hours to obtain InZrO. x / Carbon nitride catalyst.

[0019] This application also provides an InZrO x Application of carbon nitride catalysts in the photocatalytic degradation of oxytetracycline.

[0020] The beneficial effects of this invention are:

[0021] This invention uses InZrO x A highly efficient ternary composite photocatalytic system was successfully constructed by loading InZrO onto a carbon nitride matrix, and the InZrO content was further optimized. xThe optimized loading and In / Zr molar ratio design improved band structure matching, provided more abundant surface active sites, and enhanced the overall catalyst stability. This significantly promoted the separation and migration efficiency of photogenerated electron-hole pairs, greatly suppressed the recombination rate, and substantially improved the degradation rate and removal efficiency of oxytetracycline, while also exhibiting good cycle stability. The catalyst in Example 3 of this invention achieved a 95% degradation rate of oxytetracycline within 120 min, which is significantly higher than that of pure InZrO. x (38%) is 150% higher than that of pure carbon nitride (21%), and 352% higher than that of pure carbon nitride (21%). Attached image description:

[0022] Figure 1 These are the photocatalytic degradation effects of oxytetracycline using the catalysts and carbon nitride in Example 3 and Comparative Example 1.

[0023] Figure 2 This is a photocatalytic experiment cycle diagram of the catalyst prepared in Example 3. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments.

[0025] The carbon nitride described in the following examples and comparative examples was obtained by the following preparation method: melamine was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min, held at that temperature for 4 hours, cooled, and ground.

[0026] Example 1

[0027] (1) Dissolve indium nitrate and zirconium nitrate in deionized water at a molar ratio of 0.3, heat and stir at 70°C to dissolve, and prepare a metal solution;

[0028] (2) Prepare 3 mol·L -1 Ammonia solution;

[0029] (3) Add carbon nitride to deionized water and sonicate for 25 min to obtain a dispersion with a concentration of 7.5 g / L;

[0030] (4) Under stirring at 80℃, 20mL of metal salt solution and 5mL of ammonia solution were added dropwise to 131mL of dispersion, and the pH was controlled at 7.8 to form a precipitate;

[0031] (5) Continue stirring for 1 hour, age at 80℃ for 6 hours, filter and wash, and dry at 60℃ for 12 hours;

[0032] (6) Calcination at 525℃ for 4.5 h in argon atmosphere yields InZrO x / Carbon nitride catalyst; the InZrO x The quality is InZrO x / 2% of carbon nitride catalyst.

[0033] Example 2

[0034] The difference between Example 2 and Example 1 is that: the InZrO is adjusted. x The quality is InZrO x / 4% of carbon nitride catalyst, other examples 1.

[0035] Example 3

[0036] The difference between Example 3 and Example 1 is that: the InZrO is adjusted. x The quality is InZrO x / 6% of carbon nitride catalyst, other examples 1.

[0037] Example 4

[0038] The difference between Example 4 and Example 1 is that: the InZrO is adjusted. x The quality is InZrO x / 8% of carbon nitride catalyst, other examples 1.

[0039] Example 5

[0040] The difference between Example 5 and Example 1 is that: the InZrO is adjusted. x The quality is InZrO x / 5% of carbon nitride catalyst, adjusting the molar ratio of indium nitrate and zirconium nitrate to 0.1, other examples 1.

[0041] Example 6

[0042] The difference between Example 6 and Example 5 is that the molar ratio of indium nitrate and zirconium nitrate is adjusted to 0.3, while the rest is the same as in Example 5.

[0043] Example 7

[0044] The difference between Example 7 and Example 5 is that the molar ratio of indium nitrate and zirconium nitrate is adjusted to 0.5, while the rest is the same as in Example 5.

[0045] Comparative Example 1

[0046] (1) Dissolve indium nitrate and zirconium nitrate in deionized water at a molar ratio of 0.3, heat and stir at 70°C to dissolve, and prepare a metal solution;

[0047] (2) Prepare 3 mol·L -1 Ammonia solution;

[0048] (3) Under stirring at 80℃, 20mL of metal salt solution and 5mL of ammonia solution were added dropwise to 131mL of deionized water, and the pH was controlled at 7.8 to form a precipitate;

[0049] (4) Continue stirring for 1 hour, age at 80℃ for 6 hours, filter and wash, and dry at 60℃ for 12 hours;

[0050] (5) Calcination at 525℃ for 4.5 h in argon atmosphere yields InZrO x catalyst.

[0051] Example of effect

[0052] 30 mg of each of the photocatalysts prepared in the examples and comparative examples were added to 100 mL of 20 mg / L oxytetracycline solution, sonicated until homogeneous, and reacted for 60 min under dark conditions to reach adsorption-desorption equilibrium. Then, the solution was irradiated under simulated sunlight (300 W xenon lamp) for 120 min to carry out the photocatalytic degradation reaction. 3 mL samples were taken every 30 min, and the oxytetracycline content in the suspension was analyzed by UV-Vis spectrophotometry to calculate the degradation rate. The results are shown in Table 1.

[0053] Table 1

[0054] Example 1 52 Example 2 78 Example 3 95 Example 4 70 Example 5 58 Example 6 90 Example 7 65 Comparative Example 1 38 carbon nitride 21

[0055] As can be seen from Table 1, InZrO x The combination of InZrO2 and carbon nitride significantly improved the photocatalytic degradation efficiency of oxytetracycline, indicating that InZrO2... x The carbon nitride catalyst achieved a synergistic effect. Examples 1-4 show that InZrO x When the loading amount increased from 2% to 8%, the activity first increased and then decreased, with the optimal loading amount being 6% (Example 3). This indicates that if the loading amount is too low, there will be insufficient active sites, while if it is too high, it may block the carrier pores or block light absorption. Examples 5-7 show that immobilizing InZrO... x When the loading was 5%, the activity initially increased and then decreased as the In / Zr molar ratio increased from 0.1 to 0.5, with the optimal ratio of 0.3 (Example 6, 90%) indicating that an appropriate metal ratio can optimize charge separation. Example 3 (InZrO) x The loading of 6% showed the highest photocatalytic degradation rate (95%), which was significantly better than Comparative Example 1 (pure metal oxide, 38%) and pure carbon nitride (21%).

[0056] The catalyst from Example 3, after undergoing one photocatalytic degradation process, was recovered and reused after centrifugation, washing, and drying. Its stability after five photocatalytic degradation cycles was tested, and the results are shown below. Figure 2 .from Figure 2 It can be seen that after the 5th photocatalytic degradation cycle, the catalyst of Example 3 of this application still has a degradation efficiency of 89%, indicating that the catalyst structure is stable.

[0057] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An InZrO x / Carbon nitride catalyst, characterized in that The InZrO x / Carbon nitride catalyst consists of carbon nitride, InZrO x Composed of composites; the InZrO x The quality is InZrO x / 4~8% of carbon nitride catalyst; the InZrO x The molar ratio of In to Zr is 0.3~0.5; The InZrO x The application of carbon nitride catalysts is for the photocatalytic degradation of oxytetracycline.

2. An InZrO as described in claim 1 x The method for preparing carbon nitride catalyst is characterized by, Includes the following steps: (1) Dissolve indium salt and zirconium salt in deionized water, heat and stir until completely dissolved to obtain a metal salt solution; (2) Prepare an ammonia solution; (3) Add carbon nitride to deionized water and sonicate to obtain a dispersion; (4) Under stirring conditions and at 70~85℃, the metal nitrate solution and ammonia solution are dripped into the dispersion to form a precipitate, and the pH of the reaction system is maintained at 7.5~8.0; (5) Continue stirring for 1 hour, then age at 70~85℃ for 5~8 hours, filter, wash, dry, and obtain powder; (6) The powder was calcined in an inert atmosphere to obtain InZrO. x / Carbon nitride catalyst.

3. The InZrO as described in claim 2 x The method for preparing carbon nitride catalyst is characterized by, In step (1), the indium salt is indium nitrate; the zirconium salt is zirconium nitrate; and the molar ratio of the indium salt to the zirconium salt is 0.1 to 0.

5.

4. The InZrO as described in claim 2 x The method for preparing carbon nitride catalyst is characterized by, The heating and stirring temperature in step (1) is 65~75℃.

5. The InZrO as described in claim 2 x The method for preparing carbon nitride catalyst is characterized by, The concentration of the ammonia solution mentioned in step (2) is 1~5 mol·L⁻¹ -1 .

6. The InZrO as described in claim 3 x The method for preparing carbon nitride catalyst is characterized by, The concentration of carbon nitride in the dispersion in step (3) is 5~10 g / L.

7. The InZrO as described in claim 2 x The method for preparing carbon nitride catalyst is characterized by, The calcination temperature in step (6) is 500~550℃ and the time is 3~6h.

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