Preparation method and application of bismuth vanadate / copper tungstate composite sonic catalyst

Abstract

The present invention belongs to the field of composite sonic catalytic material preparation, and specifically relates to a preparation method and application of a bismuth vanadate / copper tungstate composite sonic catalyst. BiVO4 and CuCl2·2H2O are ultrasonically dissolved in distilled water, and Na2WO4·2H2O solution is added dropwise to the solution after magnetic stirring, and stirring is continued. The mixed solution is transferred to a reactor for hydrothermal synthesis reaction, and after completion, it is placed in a ventilated place for cooling; the product is vacuum filtered, washed with deionized water for several times, dried, and ground to obtain a target product. The BiVO4 / CuWO4 composite material provided by the present invention synergistically degrades tetracycline through ultrasonic catalysis with potassium persulfate, with high removal efficiency and short reaction time. Using this method, the degradation rate of tetracycline can reach 91.25±1.95% in 120 minutes under ultrasonic conditions.

Description

Technical Field

[0001] The invention belongs to the field of preparation of composite sound catalytic materials, and in particular relates to a preparation method of a bismuth vanadate / copper tungstate composite sound catalyst and application thereof. Background Art

[0002] Antibiotics, as a broad-spectrum antimicrobial drug, are widely used to treat infectious diseases in humans and animals. With the extensive use and even abuse of antibiotics, bacteria will develop multi-drug resistance, causing serious harm to agriculture, aquaculture, humans and livestock. Tetracycline is the second most produced and used antibiotic. Its prototype and metabolites enter the soil and rivers, causing serious environmental pollution and posing a huge threat to human health. There are many processes for removing tetracycline from wastewater, such as adsorption, electrolysis, photocatalysis, and chemical oxidation.

[0003] As an advanced chemical oxidation method, sonocatalysis has a good wastewater treatment effect. During the ultrasonic process, bubbles are formed by cavitation, and sonoluminescence (SL) is generated by bubble collapse, and high temperature and high pressure are generated, thereby generating a lot of active oxygen to mineralize organic matter. The addition of sonocatalysts can further improve the efficiency of sonocatalytic degradation by generating electron-hole pairs.

[0004] BiVO4 is a new type of inorganic material with excellent physical and chemical properties. It is widely used in pigments, photocatalysis and semiconductor industries. There are three main crystal structures, namely monoclinic scheelite, tetragonal zircon and tetragonal scheelite. BiVO4 is currently widely used in the field of photocatalysis, but less involved in the field of sonocatalysis. It exhibits the best photoinduced activity under visible light radiation and has a higher level in the color dimension. At the same time, it is increasingly used in catalytic degradation research due to its narrow band gap, high chemical stability, strong redox ability, non-toxicity and low cost. CuWO4 has the advantages of high catalytic activity, good chemical stability, high reusability and environmental friendliness in the ultrasonic catalytic degradation of organic pollutants.

[0005] However, single semiconductor catalyst materials have - -h + In order to improve the catalytic activity, it is proposed to couple a semiconductor (sensitizer) with a narrow Eg with an ultrasonic catalyst to form a BiVO4 / CuWO4 heterojunction structure, in order to expand the ultrasonic catalyst's efficiency in utilizing sonoluminescence and inhibiting e - -h + An effective means of compounding. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a bismuth vanadate / copper tungstate composite acoustic catalyst, which utilizes bismuth vanadate and copper tungstate to form a heterojunction to improve the separation efficiency of electron-hole pairs, thereby improving the activity of the acoustic catalytic degradation of a tetracycline pollutant model.

[0007] The technical solution adopted by the present invention is according to the following steps: a bismuth vanadate / copper tungstate composite sound catalytic material, the preparation method comprises the following steps:

[0008] 1) Dissolve BiVO4 and CuCl2·2H2O in distilled water by ultrasonic, add Na2WO4·2H2O solution to the solution after magnetic stirring, continue stirring, transfer the mixed solution to a reactor for hydrothermal synthesis reaction, and cool it in a ventilated place after completion;

[0009] 2) The product was vacuum filtered, washed with deionized water for several times, dried and then ground to obtain the target product.

[0010] In the above-mentioned bismuth vanadate / copper tungstate composite sound catalytic material, in step 1), the molar ratio of BiVO4:CuCl2·2H2O is 1:5% to 25%.

[0011] In the above-mentioned bismuth vanadate / copper tungstate composite sonic catalytic material, in step 1), the molar ratio of CuCl2·2H2O:Na2WO4·2H2O=1:1.

[0012] In the above-mentioned bismuth vanadate / copper tungstate composite sonic catalytic material, in step 1), the temperature of the hydrothermal synthesis reaction is 180° C. and the time is 12 hours.

[0013] In the above-mentioned bismuth vanadate / copper tungstate composite sound catalytic material, in step 2), the drying temperature is 60° C. and the drying time is 6 hours.

[0014] Application of the above-mentioned bismuth vanadate / copper tungstate composite sonocatalytic material in catalytic degradation of organic pollutants.

[0015] In the above application, the organic pollutant is tetracycline.

[0016] The above application method is as follows: adding the above bismuth vanadate / copper tungstate composite sound catalytic material into wastewater containing tetracycline and ultrasonicating.

[0017] In the above application, bismuth vanadate / copper tungstate composite sonic catalytic material is added to a solution containing tetracycline, the amount of bismuth vanadate / copper tungstate composite sonic catalytic material added is 1.0 mg / mL, the concentration of the tetracycline solution is 45 mg / L, the ultrasonic power is 500 W, and the ultrasound is performed for 120 minutes.

[0018] In the above application, the above bismuth vanadate / copper tungstate composite sound catalytic material is added to wastewater containing tetracycline, and potassium persulfate is added at the same time.

[0019] The beneficial effects of the present invention are:

[0020] The bismuth vanadate / copper tungstate composite sonic catalytic material of the present invention utilizes the good catalytic performance of bismuth vanadate and copper tungstate, and their composite produces a synergistic effect, thereby improving the catalytic efficiency and reaction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the XRD pattern of the prepared BiVO4 / CuWO4 composite material.

[0022] Figure 2 This is a graph showing the effect of the prepared BiVO4 / CuWO4 composite ratio on the degradation effect of tetracycline solution.

[0023] Figure 3 This is a diagram showing the effect of ultrasonic catalytic degradation of tetracycline by BiVO4 / CuWO4 composite material (15%) and different amounts of potassium persulfate added. DETAILED DESCRIPTION

[0024] Example 1 Preparation of BiVO4

[0025] Accurately weigh 10 mmol (4.85 g) of Bi(NO3)3·5H2O and dissolve it in 5 mL of concentrated nitric acid. Then add deionized water to dilute it to 20 mL and stir it magnetically for a while to obtain a clear solution A.

[0026] Accurately weigh 20.0 g of NaOH (0.5 mol) into a beaker, add deionized water to fully dissolve it, then transfer it to a 250 mL volumetric flask and make up the volume. After shaking well, 2 mol / L NaOH solution B can be obtained.

[0027] Accurately weigh 10 mmol (1.16 g) of NH4VO3, dissolve it in 20 mL of solution B, and stir with a glass rod until the solution is uniform and clear to obtain solution C.

[0028] Under continuous stirring with a glass rod, solution C was added dropwise to solution A to obtain a yellow solution. Solution B was used to adjust the pH of the mixed solution. After the pH was adjusted to 6 and stabilized, the mixture was magnetically stirred for 30.0 min. The mixture was poured into a polytetrafluoroethylene reactor, which was placed in a blast drying oven and reacted at 180°C for 24 h. After cooling to room temperature, the filter was filtered, and the filter residue was rinsed with deionized water three times, and then washed with anhydrous ethanol three times. Finally, the product was placed in a vacuum drying oven for drying. After the product was completely dried, it was ground and transferred to a sealed centrifuge tube to obtain a BiVO4 powder sample.

[0029] Example 2 Preparation of BiVO4 / CuWO4 composite material

[0030] Weigh 323.9 mg (1 mol) of BiVO4 and a certain amount of CuCl2·2H2O (0.05-0.25 mol) into a 250 mL conical flask, add 60 mL of distilled water, place it in an ultrasonic cleaner for 30 min, add a stirrer, and then transfer it to a magnetic stirrer. After stirring for 30 min, slowly add 20 mL of a certain concentration of Na2WO4·2H2O solution, continue stirring for 60 min, and finally transfer the mixture to a reactor. Heat the air drying oven to 180°C in advance, place the reactor in it for a 12 h synthesis reaction, take it out after the end and place it in a ventilated place to cool, filter the product in turn, wash, dry it, grind it, and transfer it to a sealed centrifuge tube to obtain a BiVO4 / CuWO4 sample. The molar ratios of the composite catalysts of 5%, 10%, 15%, 20% and 25% are respectively BiVO4:CuWO4=1:5%, 1:10%, 1:15%, 1:20% and 1:25%.

[0031] Example 3 Characterization and Analysis of BiVO4 / CuWO4 Composite Materials

[0032] Figure 1 The following are the XRD patterns of BiVO4 / CuWO4 at different molar ratios. Figure 1 It can be seen that the peak values ​​of 2θ are 15.1°, 18.6°, 18.9°, 28.5°, 28.8°, 30.5°, 34.5°, 35.2°, 37.8°, 42.4°, 54.6°, and 59.2°, respectively, corresponding to the (020), (110), (011), (-130), (-121), (040), (200), (002), (220), (051), (013), and (123) planes of BiVO4 (JCPDS No.14-0688). Figure 1 In the spectrum of the BiVO4 / CuWO4 composite material, the shape of the diffraction peak is very sharp, indicating that the synthesized BiVO4 / CuWO4 has good crystallinity. The lack of characteristic peaks of CuWO4 may be due to its too low content.

[0033] Example 4 Effect of BiVO4 / CuWO4 composite material on catalytic ultrasonic degradation of tetracycline solution

[0034] 20 mg of BiVO4 / CuWO4 powder and 20 mL of 45 mg / L TET solution were added to a conical flask to mix, and then placed in an ultrasonic cleaner. The ultrasonic power was set to 500 W and ultrasonicated for 120 min under light-shielding conditions. After the ultrasonication, the catalyst was filtered out with a filter head, and the absorbance was detected with an ultraviolet spectrophotometer. The data were recorded and saved. The degradation rate of TET can be calculated using formula (1).

[0035] The formula is: Degradation rate (%) = [(A0-A t ) / A0]×100% (1)

[0036] A0 is the initial absorbance of tetracycline, A t is the absorbance of the tetracycline solution after degradation in each experiment.

[0037] In addition, the degradation rate of TET solution is max = Calculated by absorbance at 350 nm.

[0038] The results are as follows Figure 2 As shown, when the composite ratio is 15%, the degradation effect of the synthesized BiVO4 / CuWO4 catalyst is the best, and the degradation rate can reach 79.03±1.72%. The composite of BiVO4 and CuWO4 forms an S-type heterojunction, which can adjust its electronic structure and improve the disadvantage of high electron-hole recombination rate, thus enhancing its degradation efficiency.

[0039] Example 5 Effect of BiVO4 / CuWO4 composite material and potassium persulfate on the synergistic ultrasonic catalytic degradation of tetracycline solution

[0040] 20 mg of BiVO4 / CuWO4 powder and 20 mL of 25 mg / L TET solution were added to a conical flask to mix them. Potassium persulfate was added to the conical flask in amounts of 2 mg, 5 mg, 10 mg, and 20 mg, respectively. The flask was then placed in an ultrasonic cleaner and ultrasonicated for (0 to 120) min under light shielding conditions at an ultrasonic power of 500 W. After the ultrasonication, the catalyst was filtered out with a filter. The absorbance was detected with an ultraviolet spectrophotometer. The data were recorded and saved. The degradation rate of TET can be calculated using formula (1).

[0041] The results are as follows Figure 3As shown in the figure, with the increase of potassium persulfate concentration, the degradation effect of tetracycline gradually increases. When the amount of potassium persulfate added is 20 mg, the degradation rate of tetracycline can reach 91.25±1.95% at 120 min. As shown in the following formula 2-4, the addition of K2S2O8 produces more active substances and significantly improves its degradation rate. The experimental results prove that the BiVO4 / CuWO4 composite material and potassium persulfate synergistic ultrasonic catalytic degradation of tetracycline solution has the characteristics of high removal efficiency, short reaction time and low cost.

[0042] H + +S2O8 2- →HS2O8 - (2)

[0043] HS2O8 - →H + +SO4 2- +SO4 - (3)

[0044] H2O+SO4 - →H + + OH+SO4 2- (4)

Claims

1. Application of a bismuth vanadate / copper tungstate composite sonic catalytic material in catalytic degradation of organic pollutants, characterized in that: The bismuth vanadate / copper tungstate composite sonic catalytic material is added into the wastewater containing tetracycline and ultrasonicated; The preparation method of the bismuth vanadate / copper tungstate composite sound catalytic material comprises the following steps: 1) Dissolve BiVO4 and CuCl2·2H2O in distilled water by ultrasonic, add Na2WO4·2H2O solution to the solution after magnetic stirring, continue stirring, transfer the mixed solution to a reactor for hydrothermal synthesis reaction, and cool in a ventilated place after completion; in molar ratio, BiVO4:CuCl2·2H2O=1: 5%~20%, CuCl2·2H2O:Na2WO4·2H2O=1:1; 2) The product was vacuum filtered, washed with deionized water several times, dried and then ground to obtain the target product.

2. The use according to claim 1, characterized in that: In step 1), the temperature of the hydrothermal synthesis reaction is 180 °C and the time is 12 h.

3. The use according to claim 1, characterized in that: In step 2), the drying temperature is 60°C and the drying time is 6 hours.

4. The use according to claim 1, characterized in that: A bismuth vanadate / copper tungstate composite sonic catalytic material was added to a solution containing tetracycline, wherein the amount of the bismuth vanadate / copper tungstate composite sonic catalytic material added was 1.0 mg / mL, the concentration of the tetracycline solution was 45 mg / L, the ultrasonic power was 500 W, and the ultrasound was performed for 120 min.

5. The use according to claim 4, characterized in that: The bismuth vanadate / copper tungstate composite acoustic catalytic material is added into the wastewater containing tetracycline, and potassium persulfate is added at the same time.

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