InZrOx / carbon nitride catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oxytetracycline photocatalytic degradation, and particularly relates to an InZrOx / carbon nitride catalyst as well as a preparation method and application thereof. The InZrOx / carbon nitride catalyst is formed by compounding carbon nitride and InZrOx, an efficient ternary composite photocatalytic system is constructed, the loading capacity of the InZrOx and the design of the molar ratio of In to Zr are further optimized, matching of an energy band structure is optimized, meanwhile, richer surface active sites are provided, the photocatalytic activity is improved, the stability of the catalyst is enhanced, and the photocatalytic performance of the catalyst is improved. The method is suitable for oxytetracycline-containing anhydrous efficient sunlight-driven degradation, and has large-scale popularization potential.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oxytetracycline photocatalytic degradation, and particularly relates to an InZrO x / carbon nitride catalyst and a preparation method and application thereof. BACKGROUND

[0002] Oxytetracycline (OTC) is a broad-spectrum antibiotic widely used in animal husbandry and aquaculture. Its large-scale use and improper discharge result in its wide residue in natural water bodies and soil environments. OTC has environmental persistence, biological accumulation and potential ecological toxicity, can induce the generation and spread of resistance genes, and poses a serious threat to the ecological system and human health. Therefore, it is crucial to develop an efficient, economical and environmentally friendly OTC removal technology.

[0003] Photocatalytic technology has great potential in the field of environmental remediation due to its ability to directly utilize solar energy to drive pollutant degradation, simple operation and no secondary pollution. Graphitic carbon nitride (g-C3N4) is a non-metallic, visible light responsive semiconductor photocatalyst that has been widely studied due to its good chemical stability, non-toxicity, easy synthesis and suitable energy band structure. However, the original g-C3N4 has inherent defects such as small specific surface area, high recombination rate of photo-generated carriers, and limited visible light utilization, which makes its photocatalytic activity difficult to meet the demand of practical application.

[0004] To overcome the shortcomings of g-C3N4, researchers have used metal oxides to modify it. Metal oxides can act as cocatalysts or construct heterojunctions, effectively promoting the separation and migration of photo-generated electron-hole pairs, expanding the light response range, and possibly providing additional active sites. Various metal oxides (such as TiO2, ZnO, WO3, Fe2O3, etc.) have been used to modify g-C3N4 to improve its photocatalytic performance. However, finding new metal oxide composite systems with higher synergistic effect, better stability and controllable cost, especially for the degradation of difficult-to-degrade organic pollutants such as OTC, is still a hot and difficult point in current research. SUMMARY

[0005] In view of the shortcomings of the prior art, the application provides an InZrO x / carbon nitride catalyst and a preparation method thereof.

[0006] The InZrO x / carbon nitride catalyst is composed of carbon nitride and InZrO x The mass of the InZrO x is 2-8% of the InZrO x / carbon nitride catalyst.

[0007] Further, the InZrO x The molar ratio of In and Zr is 0.1-0.5.

[0008] Further, the InZrO x The preparation method of the InZrO

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

[0010] Further, the indium salt is indium nitrate, and the zirconium salt is zirconium nitrate.

[0011] Further, the molar ratio of the indium salt and the zirconium salt is 0.1-0.5.

[0012] Further, the heating and stirring temperature is 65-75℃.

[0013] (2) Prepare an ammonia water solution with a concentration of 1-5 mol·L -1 .

[0014] (3) Add carbon nitride to deionized water, and after ultrasonic treatment for 10-40 min, obtain a dispersion.

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

[0016] (4) Under stirring conditions and at 70-85℃, flow drop the metal nitrate solution and the ammonia water solution into the dispersion to generate a precipitate, and keep the pH of the reaction system at 7.5-8.0.

[0017] (5) Continue stirring for 1 h, and then age at 70-85℃ for 5-8 h, filter, wash, and dry to obtain a powder.

[0018] (6) Place the powder in an inert atmosphere, heat to 500-550℃, and calcine for 3-6 h to obtain an InZrO x / carbon nitride catalyst.

[0019] The application also provides an application of the InZrO x / carbon nitride catalyst in photocatalytic degradation of terramycin.

[0020] The application has the following beneficial effects:

[0021] The application successfully constructs a high-efficiency ternary composite photocatalytic system by loading InZrO x on a carbon nitride matrix, and further optimizes the InZrO xThe load amount and the molar ratio of In and Zr are designed to optimize the matching of the energy band structure, provide more abundant surface active sites and enhance the stability of the overall catalyst, significantly promote the separation and migration efficiency of the photo-generated electron-hole pairs, greatly inhibit the recombination rate, and greatly improve the degradation rate and removal efficiency of terramycin, and have good cycle stability. The catalyst of Example 3 realizes 95% of the terramycin degradation rate within 120 minutes, which is increased by 150% compared with pure InZrO x (38%) and is increased by 352% compared with pure carbon nitride (21%). BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a photocatalytic degradation terramycin effect diagram of the catalyst of Example 3, Comparative Example 1 and carbon nitride;

[0023] Figure 2 is a cycle diagram of the photocatalytic experiment of the catalyst prepared in Example 3. DETAILED DESCRIPTION

[0024] The application will be further described below in combination with examples.

[0025] The carbon nitride described in the following examples and comparative examples is obtained by the following preparation method: melamine is placed in a tube furnace, heated to 550℃ at a heating rate of 2.5℃ / min, kept for 4h, cooled, and ground.

[0026] Example 1

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

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

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

[0030] (4) Under stirring at 80℃, drop 20mL of metal salt solution and 5mL of ammonia solution into 131mL of dispersion liquid, control pH=7.8, and generate a precipitate;

[0031] (5) Continue to stir for 1h, age at 80℃ for 6h, filter and wash, and dry at 60℃ for 12h;

[0032] (6) Calcine at 525℃ for 4.5h in argon to obtain InZrO x / carbon nitride catalyst; the mass of the InZrO x is 2% of the mass of the InZrO x / carbon nitride catalyst.

[0033] Example 2

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

[0035] Example 3

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

[0037] Example 4

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

[0039] Example 5

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

[0041] Example 6

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

[0043] Example 7

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

[0045] Comparative Example 1

[0046] (1) dissolving indium nitrate and zirconium nitrate in a molar ratio of 0.3 in deionized water, heating and stirring at 70° C. to dissolve, and preparing a metal solution;

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

[0048] (3) Under stirring at 80°C, 20 mL of the metal salt solution and 5 mL of an ammonia solution were added dropwise to 131 mL of deionized water, with the pH controlled at 7.8, to generate a precipitate.

[0049] (4) Continue stirring for 1 h, age at 80 °C for 6 h, filter and wash, and dry at 60 °C for 12 h;

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

[0051] Effect Examples

[0052] 30 mg of each of the photocatalysts prepared in the Examples and Comparative Examples were added to 100 mL of a 20 mg / L oxytetracycline solution, homogenized with ultrasound, and allowed to react for 60 minutes in the absence of light to reach adsorption and desorption equilibrium. The mixture was then irradiated under simulated sunlight (xenon lamp, 300 W) for 120 minutes to allow photocatalytic degradation to proceed. 3 mL of the sample was sampled every 30 minutes, and the oxytetracycline content in the suspension was analyzed by UV-visible spectrophotometry to calculate the degradation rate. The results are shown in Table 1.

[0053] Table 1

[0054] Degradation rate (%) 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 After being compounded with InZrO and carbon nitride, the efficiency of photocatalytic degradation of oxytetracycline was significantly improved, which showed that InZrO x / carbon nitride catalysts achieve a synergistic effect. Examples 1-4 show that InZrO x When the loading amount increases from 2% to 8%, the activity first increases and then decreases, and the optimal loading amount is 6% (Example 3), indicating that if the loading amount is too low, the active sites are insufficient, and if it is too high, the carrier pores may be blocked or light absorption may be shielded. Examples 5-7 show that the fixed InZrO x When the loading amount is 5%, the activity increases from 0.1 to 0.5 with the In / Zr molar ratio, and the optimal ratio is 0.3 (Example 6, 90%), indicating that the appropriate metal ratio can optimize charge separation. Example 3 (InZrO x The photocatalytic degradation rate of the composite was 95% (with a loading of 6%), which was significantly better than that of the comparative example 1 (pure metal oxide, 38%) and pure carbon nitride (21%).

[0056] The catalyst of Example 3 which had undergone one photocatalytic degradation process was centrifuged, washed, dried, recovered and reused, and its stability after five photocatalytic degradation cycles was tested. The test results are shown in FIG. Figure 2 .from Figure 2 It can be seen that after the fifth photocatalytic degradation cycle, the catalyst of Example 3 of the present application still has a degradation efficiency of 89%, indicating that the catalyst structure is stable.

[0057] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. InZrO x / Carbon nitride catalyst, characterized in that The InZrO x / Carbon nitride catalyst is composed of carbon nitride, InZrO x Composite; the InZrO x The mass of InZrO x / 2 to 8% of the carbon nitride catalyst.

2. InZrO according to claim 1 x / Carbon nitride catalyst, characterized in that The InZrO x The molar ratio of In to Zr is 0.1 to 0.

5.

3. InZrO according to claim 1 or 2 x / A method for preparing a carbon nitride catalyst, characterized in that: The steps include: (1) dissolving indium salt and zirconium salt in deionized water, heating and stirring to completely dissolve them, to obtain a metal salt solution; (2) preparing an ammonia solution; (3) adding carbon nitride to deionized water and sonicating to obtain a dispersion; (4) adding the metal nitrate solution and the ammonia solution dropwise to the dispersion under stirring at 70-85° C. to form a precipitate, and maintaining the pH of the reaction system at 7.5-8.0; (5) Continue stirring for 1 hour, then age at 70-85°C for 5-8 hours, filter, wash, and dry to obtain a powder; (6) The powder is calcined in an inert atmosphere to obtain InZrO x / Carbon nitride catalyst.

4. InZrO as claimed in claim 3 x / A method for preparing a carbon nitride catalyst, characterized in that: 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.

5. InZrO as claimed in claim 3 x / A method for preparing a carbon nitride catalyst, characterized in that: The heating and stirring temperature in step (1) is 65-75°C.

6. InZrO as claimed in claim 3 x / A method for preparing a carbon nitride catalyst, characterized in that: The concentration of the ammonia solution in step (2) is 1 to 5 mol·L -1 .

7. InZrO as claimed in claim 3 x / A method for preparing a carbon nitride catalyst, characterized in that: The concentration of carbon nitride in the dispersion in step (3) is 5 to 10 g / L.

8. InZrO as claimed in claim 3 x / A method for preparing a carbon nitride catalyst, characterized in that: The calcination temperature in step (6) is 500-550° C. and the calcination time is 3-6 hours.

9. The metal InZrO according to claim 1 or 2 x / Application of a carbon nitride catalyst, characterized in that The application is photocatalytic degradation of oxytetracycline.

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