A bismuth vanadate / iron vanadate composite sono-catalyst, a preparation method and application thereof

Abstract

The application discloses a BiVO4 / FeVO4 composite sono-catalyst, a preparation method and application thereof. Bi(NO3)3.5H2O and Fe(NO3)3.9H2O are taken, nitric acid solution is added for dissolution, and then NH4VO3 NaOH solution is slowly added after being uniformly mixed, the pH of the solution is adjusted, the mixed solution is uniformly stirred, and then is transferred into a reaction kettle for hydrothermal synthesis reaction, and then is cooled to room temperature, filtered, washed, dried, and calcined at high temperature in a tube furnace to obtain the BiVO4 / FeVO4 composite sono-catalyst. The composite material provided by the application can synergistically act with potassium persulfate to remove tetracycline under ultrasonic catalysis, has high removal efficiency and short reaction time. The removal rate of tetracycline under ultrasonic conditions for 120 min can reach 94.80% by using the method.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of sono-catalytic composite materials, and particularly relates to a bismuth vanadate / iron vanadate composite sono-catalyst as well as a preparation method and application thereof. BACKGROUND

[0002] Tetracycline is widely used in human and animal therapeutic applications due to its broad spectrum, high efficiency and reasonable cost. However, due to the high stability of tetracycline, tetracycline residues are released into aquatic environments. The presence of tetracyclines in the environment can hinder the function of soil microorganisms and also have toxicity or teratogenic effects on plants and animals. In addition, it also contributes to the emergence and spread of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARBs). Considering the difficulty of removing tetracycline in the water environment, it is necessary to study effective methods to remove tetracycline.

[0003] There are adsorption, electrolysis, photocatalysis, chemical oxidation and other processes for the removal of tetracycline in wastewater. Sono-catalysis as an advanced chemical oxidation method has good wastewater treatment effect. In the ultrasonic process, bubbles are formed by cavitation, and sonoluminescence (SL) and high temperature and pressure are generated by bubble rupture, thereby generating many active oxygen to mineralize organic matter, and the addition of sono-catalyst can further improve the efficiency of sono-catalytic removal by generating electron-hole pairs.

[0004] BiVO4 is a semiconductor material with a small band gap, which enables it to effectively absorb visible light and generate electron-hole pairs required for photocatalysis. Among them, monoclinic scheelite BiVO4 has been proven to be an efficient photocatalyst, not only has the characteristics of low manufacturing cost, small harm, good light stability, etc., but also is a very potential material. However, although the mechanism of photocatalysis and sono-catalysis is similar, the sono-catalytic activity of BiVO4 is limited by its high light-induced recombination degree and insufficient surface adsorption properties, resulting in low sono-catalytic efficiency. SUMMARY

[0005] The purpose of the present application is to provide a bismuth vanadate / iron vanadate composite sono-catalyst, which utilizes the formation of a heterojunction between bismuth vanadate and iron vanadate to improve the separation efficiency of electron-hole pairs, thereby improving the sono-catalytic removal of tetracycline pollutants.

[0006] The technical scheme adopted by the present application is as follows: a bismuth vanadate / iron vanadate composite sono-catalyst, the preparation method comprising the following steps: taking Bi(NO3)3·5H2O and Fe(NO3)3·9H2O, dissolving with a nitric acid solution, mixing uniformly, then slowly adding a NaOH solution of NH4VO3, adjusting the pH of the solution, stirring uniformly, then transferring the mixed solution to a reaction kettle for hydrothermal synthesis reaction, cooling to room temperature, filtering, washing, drying, and calcining at high temperature in a tube furnace to obtain the bismuth vanadate / iron vanadate composite sono-catalyst (BiVO4 / FeVO4).

[0007] Further, the molar ratio of Bi(NO3)3·5H2O:Fe(NO3)3·9H2O is 10:(2-7).

[0008] Further, the molar ratio of Bi(NO3)3·5H2O:NH4VO3 is 10:(12-17).

[0009] Further, the pH of the solution is adjusted to 1.5-2.5.

[0010] Further, the hydrothermal synthesis reaction is carried out at 175-185℃ for 22-26h.

[0011] Further, the high-temperature calcination is carried out at a calcination temperature of 450-550℃, a calcination holding time of 4-5h, and a heating rate of 5℃ / min.

[0012] The application provides an application of a bismuth vanadate / iron vanadate composite sono-catalyst in catalytic removal of organic pollutants.

[0013] Further, the organic pollutants are tetracycline.

[0014] Further, the method is as follows: the bismuth vanadate / iron vanadate composite sono-catalyst is added to wastewater containing tetracycline, and ultrasonic treatment is performed.

[0015] Further, the addition amount of the bismuth vanadate / iron vanadate composite sono-catalyst is 1.0-1.5mg / mL, the concentration of tetracycline is 40-60mg / L, the ultrasonic power is 500W, and the ultrasonic time is 100-150min.

[0016] Further, potassium persulfate is added simultaneously.

[0017] Further, the addition amount of potassium persulfate is 0.25-3.0mg / mL.

[0018] The application has the following beneficial effects:

[0019] In the application, FeVO4 and BiVO4 are combined to form a heterojunction structure. FeVO4, as a semiconductor photocatalyst, has the advantages of ultraviolet visible light driving, small band gap, chemical and thermal stability, and non-toxicity, and can effectively promote the separation and migration of electron-hole pairs and produce strong hole oxidation capacity. In the application, FeVO4 and BiVO4 are combined to form a heterojunction structure, which greatly improves the sono-catalytic activity, thereby realizing a more efficient sono-catalytic process.

[0020] In the application, the bismuth vanadate / iron vanadate composite sono-catalytic material utilizes the good catalytic performance of bismuth vanadate and iron vanadate, and the combination of them produces a synergistic effect, thereby improving the catalytic efficiency and reaction rate. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 XPS spectrum of the prepared BiVO4 / FeVO4 composite material.

[0022] Figure 2 Effect of BiVO4 / FeVO4 composite materials prepared at different composite ratios on the removal of tetracycline solution.

[0023] Figure 3 Effect of BiVO4 / FeVO4 composite materials with a composite ratio of 60% and different amounts of added potassium persulfate on the removal of tetracycline by ultrasonic catalysis. DETAILED DESCRIPTION

[0024] Example 1: Bismuth vanadate / iron vanadate composite sonocatalyst (BiVO4 / FeVO4)

[0025] (I) BiVO4 / FeVO4 with a composite ratio of 20%

[0026] The preparation method is as follows:

[0027] Fe(NO3)3·9H2O (808 mg, 2 mmol) and Bi(NO3)3·5H2O (4850.7 mg, 10 mmol) were weighed and dissolved in 2 mL of concentrated nitric acid, then diluted with deionized water to 20 mL, and a clear solution A was obtained after magnetic stirring for a period of time. NH4VO3 (1404 mg, 12 mmol) was dissolved in 20 mL of 2 mol / L NaOH solution to obtain solution B. Under stirring, solution B was added dropwise to solution A to form a yellow solution, then the pH value of the mixed solution was adjusted to 2 with 2 mol / L NaOH solution and stabilized, and then magnetic stirring was continued for 30 min. The obtained mixture was transferred to a polytetrafluoroethylene reaction kettle and placed in a blast drying oven for reaction at 180°C for 24 h; after cooling to room temperature, it was suction filtered, the filter residue was washed with deionized water three times, then washed with anhydrous ethanol three times. Finally, the product was placed in a vacuum drying oven and dried at 60°C for 6 h, then ground and calcined at 500°C in a tube furnace (the temperature rising speed was 5°C / min) for 4 h to obtain a BiVO4 / FeVO4 composite material with a molar ratio of Bi(NO3)3·5H2O:Fe(NO3)3·9H2O = 10:2, and a Fe(NO3)3·9H2O composite ratio of 20%.

[0028] (II) BiVO4 / FeVO4 with a composite ratio of 30%

[0029] The preparation method is as follows:

[0030] Fe(NO3)3-9H2O (1212 mg, 3 mmol) and Bi(NO3)3-5H2O (4850.7 mg, 10 mmol) were weighed and dissolved in 2 mL of concentrated nitric acid, then deionized water was added to dilute to 20 mL, and a clear solution A was obtained after magnetic stirring for a period of time. NH4VO3 (1521 mg, 13 mmol) was weighed and dissolved in 20 mL of 2 mol / L NaOH solution to obtain solution B. Solution B was added dropwise to solution A under stirring to form a yellow solution, then the pH of the mixed solution was adjusted to 2 with 2 mol / L NaOH solution and stabilized, and then magnetic stirring was continued for 30 min. The obtained mixture was transferred to a polytetrafluoroethylene reactor and placed in a blast drying oven for reaction at 180°C for 24 h; after cooling to room temperature, suction filtration was performed, the filter residue was washed with deionized water three times, and then washed with anhydrous ethanol three times. Finally, the product was dried in a vacuum drying oven, ground after drying at 60°C for 6 h, and calcined at 500°C for 4 h in a tube furnace (the heating rate was 5°C / min) to obtain a BiVO4 / FeVO4 composite material with a molar ratio of Bi(NO3)3-5H2O:Fe(NO3)3-9H2O = 10:3 and a Fe(NO3)3-9H2O composite ratio of 30%.

[0031] (III) BiVO4 / FeVO4 with a composite ratio of 30%

[0032] The preparation method is as follows:

[0033] Fe(NO3)3-9H2O (1616 mg, 4 mmol) and Bi(NO3)3-5H2O (4850.7 mg, 10 mmol) were weighed and dissolved in 2 mL of concentrated nitric acid, then deionized water was added to dilute to 20 mL, and a clear solution A was obtained after magnetic stirring for a period of time. NH4VO3 (1638 mg, 14 mmol) was weighed and dissolved in 20 mL of 2 mol / L NaOH solution to obtain solution B. Solution B was added dropwise to solution A under stirring to form a yellow solution, then the pH of the mixed solution was adjusted to 2 with 2 mol / L NaOH solution and stabilized, and then magnetic stirring was continued for 30 min. The obtained mixture was transferred to a polytetrafluoroethylene reactor and placed in a blast drying oven for reaction at 180°C for 24 h; after cooling to room temperature, suction filtration was performed, the filter residue was washed with deionized water three times, and then washed with anhydrous ethanol three times. Finally, the product was dried in a vacuum drying oven, ground after drying at 60°C for 6 h, and calcined at 500°C for 4 h in a tube furnace (the heating rate was 5°C / min) to obtain a BiVO4 / FeVO4 composite material with a molar ratio of Bi(NO3)3-5H2O:Fe(NO3)3-9H2O = 10:4 and a Fe(NO3)3-9H2O composite ratio of 40%.

[0034] (iv) BiVO4 / FeVO4 with a composite ratio of 50%

[0035] The preparation method is as follows:

[0036] Fe(NO3)3·9H2O (2020 mg, 5 mmol) and Bi(NO3)3·5H2O (4850.7 mg, 10 mmol) were weighed and dissolved in 2 mL of concentrated nitric acid, then diluted with deionized water to 20 mL, and a clear solution A was obtained after magnetic stirring for a period of time. NH4VO3 (1755 mg, 15 mmol) was dissolved in 20 mL of 2 mol / L NaOH solution to obtain solution B. Under stirring, solution B was added dropwise to solution A to form a yellow solution, then the pH value of the mixed solution was adjusted to 2 with 2 mol / L NaOH solution and stabilized, and then magnetic stirring was continued for 30 min. The obtained mixture was transferred to a polytetrafluoroethylene reactor and placed in a blast drying oven for reaction at 180°C for 24 h; after cooling to room temperature, suction filtration was performed, the filter residue was washed with deionized water three times, then washed with anhydrous ethanol three times. Finally, the product was dried in a vacuum drying oven, dried at 60°C for 6 h, then ground, and calcined at 500°C for 4 h in a tube furnace (the temperature rising speed was 5°C / min) to obtain BiVO4 / FeVO4 composite material with a molar ratio of Bi(NO3)3·5H2O:Fe(NO3)3·9H2O = 10:5, and a composite ratio of Fe(NO3)3·9H2O of 50%.

[0037] (v) BiVO4 / FeVO4 with a composite ratio of 60%

[0038] The preparation method is as follows:

[0039] Fe(NO3)3-9H2O (2424 mg, 6 mmol) and Bi(NO3)3-5H2O (4850.7 mg, 10 mmol) were weighed and dissolved in 2 mL of concentrated nitric acid, then deionized water was added to dilute to 20 mL, and a clear solution A was obtained after magnetic stirring for a period of time. NH4VO3 (1872 mg, 16 mmol) was weighed and dissolved in 20 mL of 2 mol / L NaOH solution to obtain solution B. Solution B was added dropwise to solution A under stirring to form a yellow solution, then the pH of the mixed solution was adjusted to 2 with 2 mol / L NaOH solution and stabilized, and then magnetic stirring was continued for 30 min. The obtained mixture was transferred to a polytetrafluoroethylene reactor and placed in a blast drying oven for reaction at 180°C for 24 h; after cooling to room temperature, suction filtration was performed, the filter residue was washed with deionized water three times, and then washed with anhydrous ethanol three times. Finally, the product was dried in a vacuum drying oven, ground after drying at 60°C for 6 h, and calcined at 500°C for 4 h in a tube furnace (the temperature rising speed was 5°C / min) to obtain a BiVO4 / FeVO4 composite material with a molar ratio of Bi(NO3)3-5H2O:Fe(NO3)3-9H2O = 10:6 and a Fe(NO3)3-9H2O composite ratio of BiVO4 / FeVO4 of 60%.

[0040] (VI) BiVO4 / FeVO4 with a composite ratio of 70%

[0041] The preparation method is as follows:

[0042] Fe(NO3)3-9H2O (2828 mg, 7 mmol) and Bi(NO3)3-5H2O (4850.7 mg, 10 mmol) were weighed and dissolved in 2 mL of concentrated nitric acid, then deionized water was added to dilute to 20 mL, and a clear solution A was obtained after magnetic stirring for a period of time. NH4VO3 (1989 mg, 17 mmol) was weighed and dissolved in 20 mL of 2 mol / L NaOH solution to obtain solution B. Solution B was added dropwise to solution A under stirring to form a yellow solution, then the pH of the mixed solution was adjusted to 2 with 2 mol / L NaOH solution and stabilized, and then magnetic stirring was continued for 30 min. The obtained mixture was transferred to a polytetrafluoroethylene reactor and placed in a blast drying oven for reaction at 180°C for 24 h; after cooling to room temperature, suction filtration was performed, the filter residue was washed with deionized water three times, and then washed with anhydrous ethanol three times. Finally, the product was dried in a vacuum drying oven, ground after drying at 60°C for 6 h, and calcined at 500°C for 4 h in a tube furnace (the temperature rising speed was 5°C / min) to obtain a BiVO4 / FeVO4 composite material with a molar ratio of Bi(NO3)3-5H2O:Fe(NO3)3-9H2O = 10:7 and a Fe(NO3)3-9H2O composite ratio of BiVO4 / FeVO4 of 70%.

[0043] (vii) Characterization

[0044] Figure 1 XPS spectra of BiVO4, FeVO4 and BiVO4 / FeVO4 (composite ratio of 60%). The XPS spectra show that there are Bi, V, O and Fe elements in BiVO4 / FeVO4. The results confirm that the composite material synthesized by the application is composed of BiVO4 and FeVO4 nanoparticles.

[0045] Example 2 Effect of BiVO4 / FeVO4 composite material on catalytic ultrasonic removal of tetracycline solution (i) Effect of BiVO4 / FeVO4 composite material with different composite ratios on ultrasonic removal of tetracycline

[0046] The method is as follows: 25 mg of BiVO4 / FeVO4 powder and 20 mL of 50 mg / L tetracycline (TET) solution are added to a conical flask, mixed, and then placed in an ultrasonic cleaner, set to 500 W, and ultrasonicated in the dark for 120 min. After ultrasonication, the catalyst is filtered off with a filter head, and the absorbance is detected with a UV spectrophotometer. The data is recorded and saved, and the removal rate of tetracycline is calculated according to formula (1).

[0047] Removal rate (%) = [(A0-A t ) / A0] x 100% (1)

[0048] Where A0 is the initial absorbance of tetracycline, and A t is the absorbance of the tetracycline solution after removal.

[0049] In addition, the removal rate of the TET solution is calculated based on the absorbance at its λ max = 350 nm.

[0050] The results are shown in Figure 2 When the composite ratio is 60%, the synthesized bismuth vanadate / iron vanadate catalyst has the best removal effect, with a removal rate of 71.13 ± 2.06%. This is because the composite of bismuth vanadate and iron vanadate forms an S-type heterojunction, which can adjust its electronic structure and improve the disadvantage of high electron-hole recombination rate, thus improving the removal effect.

[0051] (ii) Effect of BiVO4 / FeVO4 composite material and potassium persulfate on synergistic ultrasonic catalytic removal of tetracycline solution

[0052] The method is as follows: 25 mg of BiVO4 / FeVO4 powder (complex ratio of 60%) and 20 mL of 50 mg / L tetracycline (TET) solution are added to a conical flask, mixed, and then 5 mg, 15 mg, 20 mg, 30 mg, and 60 mg of potassium persulfate are added to the conical flask; then it is placed in an ultrasonic cleaner, set to 500 W, and ultrasonicated for 120 min in the dark, after which the catalyst is filtered off with a filter, the absorbance is detected with a UV spectrophotometer, the data is recorded and saved, and the removal rate of tetracycline is calculated according to formula (1).

[0053] The results, as shown in Figure 3 , show that as the concentration of potassium persulfate increases, the removal effect of tetracycline gradually increases. When the amount of potassium persulfate added is 60 mg, the removal rate of tetracycline can reach 94.80±1.09% at 120 min.

[0054] H + +S2O8 2- →HS2O8 - (2)

[0055] HS2O8 - →H + +SO4 2- +SO4 - (3)

[0056] H2O+SO4 - →H + +·OH+SO4 2- (4)

[0057] As shown in the above formulae (2)-(4), the addition of K2S2O8 produces more active substances, significantly improving the removal rate. The experimental results prove that the BiVO4 / FeVO4 composite material and potassium persulfate synergistically catalyze the removal of tetracycline solution under ultrasonic conditions, with the characteristics of high removal efficiency, short reaction time, and low cost.

Claims

1. Application of a bismuth vanadate / iron vanadate composite sonocatalyst in catalytic removal of tetracycline, characterized in that, The method is as follows: the bismuth vanadate / iron vanadate composite sonocatalyst and potassium persulfate are added into tetracycline-containing wastewater, and ultrasonic treatment is carried out; the adding amount of potassium persulfate is 0.25-3.0 mg / mL, The preparation method of the bismuth vanadate / iron vanadate composite sonocatalyst comprises the following steps: Bi(NO3)3.5H2O and Fe(NO3)3.9H2O are taken, a nitric acid solution is added for dissolution, and then NH4VO3 NaOH solution is slowly added dropwise after uniform mixing; the solution pH is adjusted, and then the mixed solution is transferred into a reaction kettle for hydrothermal synthesis reaction; after cooling to room temperature, filtration, washing, and drying, high-temperature calcination is carried out in a tubular furnace to obtain the bismuth vanadate / iron vanadate composite sonocatalyst BiVO4 / FeVO4; the molar ratio of Bi(NO3)3.5H2O:Fe(NO3)3.9H2O is 10:(5-7).

2. Use according to claim 1, characterized in that, The molar ratio of Bi(NO3)3.5H2O:NH4VO3 is 10:(12-17).

3. Use according to claim 1, characterized in that, The solution pH is adjusted to 1.5-2.

5.

4. Use according to claim 1, characterized in that, The hydrothermal synthesis reaction is carried out at 175-185 ℃ for 22-26 h; the calcination temperature is 500 ℃, the calcination holding time is 4 h, and the temperature rising speed is 5 ℃ / min.

5. The use according to claim 1, characterized in that, The adding amount of the bismuth vanadate / iron vanadate composite sonocatalyst is 1.0-1.5 mg / mL, the concentration of tetracycline is 40-60 mg / L, the ultrasonic power is 500 W, and the ultrasonic time is 100-150 min.

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