Cerium oxide nanoparticle modified zinc tungstate nanorod ultrasonic visible light composite catalyst and preparation method thereof

Abstract

The present application relates to a kind of cerium oxide nanoparticle modified zinc tungstate nanorod ultrasonic visible light composite catalyst and its preparation method, first using hydrothermal method to prepare zinc tungstate nanopowder, then zinc tungstate nanopowder is mixed with cerium nitrate solution, urea is added, after adjusting pH, centrifugal separation is carried out, the product is dried and calcined, the zinc tungstate / cerium oxide nanocomposite material obtained includes two phases of ZnWO4 And CeO2, the mass fraction of CeO2 in zinc tungstate / cerium oxide nanocomposite material is 1-10%, ZnWO4 It is rod structure, its diameter is 20-40nm, ZnWO4 Nanorod surface has the CeO2 Nanoparticle of diameter 3-10nm and grows on it.The zinc tungstate / cerium oxide ultrasonic visible light composite catalyst prepared by the present application has excellent catalytic oxidation performance on rhodamine B under ultrasonic / visible light synergistic radiation.The present application synthesis process is simple, easy to operate, and the product has high purity, fills the blank in the synthesis technology field of ZnWO4 / CeO2.

Description

Technical Field

[0001] The invention relates to the technical field of ultrasonic-visible-light composite catalysts, in particular to an ultrasonic-visible-light composite catalyst modified with cerium oxide nanoparticles and zinc tungstate nanorods and a preparation method thereof. Background Art

[0002] Zinc tungstate (ZnWO4) is a wide-bandgap n-type ternary compound monoclinic semiconductor with excellent electrical and optical properties. It is also corrosion-resistant, non-toxic, and recyclable, making it suitable for photocatalytic degradation of organic pollutants in wastewater. Zhu et al. (CrystEngComm 2011, 13, 4695) prepared ZnWO4 nanorods with different aspect ratios using a hydrothermal method and degraded methyl blue under ultraviolet light. The effect of nanorods with different aspect ratios on photocatalytic performance was explored. Wang et al. (Materials Letters 2020, 264, 127417) synthesized ZnWO4 porous microspheres using a solvothermal method and tested their photocatalytic performance under ultraviolet light. The results showed that the photocatalytic performance was significantly improved. However, pure ZnWO4 has a wide bandgap (3.5 eV) and has strong light absorption only in the ultraviolet region. In addition, the high probability of photogenerated electron-hole recombination results in low photocatalytic efficiency in the visible light region.

[0003] Ultrasonic catalytic oxidation effectively degrades organic pollutants through the cavitation effect generated by ultrasound. Its advantages include concentrated energy and strong penetration, effectively overcoming the shortcomings of photocatalytic oxidation technology. In a recent study, Wang Xin et al. synthesized a ZnWO4 nanocatalyst via a hydrothermal method and used it to degrade acid chrome blue K using ultrasonic catalytic oxidation. The results demonstrated excellent catalytic activity, suggesting that ZnWO4 has promising prospects for the degradation of organic-contaminated wastewater under ultrasonic irradiation. However, single-phase ZnWO4 nanocatalysts still suffer from low quantum efficiency and a high probability of recombination between acoustically excited electrons and holes. These drawbacks leave room for improvement in the degradation efficiency of ZnWO4. Patent CN 106902847 synthesized a molybdenum disulfide / barium titanate ultrasonic-visible light composite catalyst that, through the synergistic effect of ultrasound and visible light, effectively enhances hydrogen production under visible light conditions. Guo et al. prepared ZnO / ZnS core-shell one-dimensional nanorod structures (Ultrasonics Sonochemistry 2021, 81, 105849) and showed excellent degradation performance of methylene blue dye under ultrasound-visible light composite irradiation.

[0004] At present, there are few research reports on the composite of zinc tungstate and metal oxides. The present invention aims to provide a CeO2 nanoparticle / ZnWO4 nanorod composite material that responds to the synergistic action of ultrasound / visible light. Under the synergistic action of ultrasound / visible light, the composite material generates mobile electrons and holes by excitation, and utilizes the built-in electric field between the composite semiconductors to accelerate electron migration, thereby improving the degradation efficiency of organic pollutants. Summary of the Invention

[0005] The purpose of the present invention is to provide a cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst and a preparation method thereof. The method has a simple process and is easy to operate. The reaction product has high purity and has excellent catalytic performance against organic pollutants under the synergistic effect of ultrasound / visible light, filling the gap in the field of ZnWO4 / CeO2 synthesis technology.

[0006] The present invention is specifically achieved through the following technical scheme: a cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst proposed by the present invention comprises two phases, ZnWO4 and CeO2, wherein the mass fraction of CeO2 in the composite catalyst is 1-10%, the ZnWO4 is rod-shaped with a diameter of 20-40 nm, and CeO2 nanoparticles with a diameter of 3-10 nm are attached to and grown on the surface of the ZnWO4 nanorods.

[0007] The present invention also provides a method for preparing a cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasonic-visible light composite catalyst, which comprises the following steps:

[0008] (1) Weigh a certain amount of Na2WO4·2H2O and dissolve it in a solvent. After thorough stirring and dissolution, obtain a Na2WO4 solution with a concentration of 2.5 mol / L. Add hexadecyltrimethylammonium bromide to the Na2WO4 solution and stir evenly to obtain solution A, which is set aside.

[0009] (2) Weigh a certain amount of zinc salt and dissolve it in a solvent. After sufficient stirring and dissolution, a zinc ion solution with a concentration of 2.5 mol / L is obtained, which is referred to as solution B and set aside.

[0010] (3) Weigh a certain amount of sodium salt and dissolve it in a solvent. After thorough stirring and dissolution, a sodium ion solution with a concentration of 0.5 mol / L is obtained, which is referred to as solution C and set aside.

[0011] (4) Taking 1 part of the solution A prepared in step (1) and 1 part of the solution B prepared in step (2) by volume, respectively, under stirring, the amount of solution B is added to the solution A at a drop rate of 2 to 4 mL / min, and after sufficient stirring, a suspension A is obtained; taking 1 part of the solution C by volume and adding it to the above suspension A, continuing to stir for 30 minutes to obtain a suspension B, and transferring the obtained suspension B to a reactor, placing the reactor in a muffle furnace and keeping it at 150° C. for 16 to 22 hours, and then cooling the reactor to room temperature to obtain a solvent thermal product;

[0012] (5) transferring the solvent thermal product obtained in step (4) to a high-speed centrifuge for centrifugal separation, washing the obtained solid precipitate, and then placing the washed solid product in a drying oven and drying it at 70-80° C. for 10-12 hours to obtain ZnWO4 nanopowder;

[0013] (6) Weigh a certain amount of Ce(NO3)3·6H2O and dissolve it in deionized water. After sufficient stirring, obtain a cerium nitrate solution with a concentration of 0.2 mol / L. Add a certain amount of ZnWO4 nanopowder prepared in step (5) to the cerium nitrate solution, stir and mix thoroughly to obtain suspension C.

[0014] (7) Dissolve urea in deionized water to form a 0.2 mol / L urea solution, add the urea solution to the suspension C obtained in step (6) at a dropwise rate of 4-6 mL / min, and the volume ratio of the urea solution to the suspension C is 1:1. Then, adjust the pH value to 11-12 with 25% ammonia water, and continue stirring for 2 h.

[0015] (8) The product obtained in step (7) is centrifuged in a high-speed centrifuge, the obtained solid precipitate is washed, and the washed solid product is placed in a drying oven and dried at a temperature of 80 to 100° C. for 10 to 12 hours; the dried product is placed in a muffle furnace for calcination, and then cooled to room temperature to obtain a ZnWO4 / CeO2 nanocomposite material.

[0016] Furthermore, the solvent in steps (1) and (2) is a mixture of deionized water and anhydrous ethanol, and the volume ratio of deionized water to anhydrous ethanol is (5-7):1. The volume ratio of deionized water to anhydrous ethanol is an important factor. The addition of anhydrous ethanol will reduce the diameter of the ZnWO4 nanorods, increase the specific surface area, and increase the active sites, thereby improving the catalytic performance.

[0017] Furthermore, the mass fraction of cetyltrimethylammonium bromide in the solution A of step (1) is 0.1 to 0.15%. Cetyltrimethylammonium bromide (CTAB) acts as a surfactant in the reaction, guiding the ZnWO4 crystal nuclei to form nanorod structures. If the amount added is too small, the rod-like structure cannot be formed; if the amount added is too large, the crystallization properties of ZnWO4 will be affected, thereby affecting the catalytic activity of the final product.

[0018] Furthermore, the zinc salt in step (2) is any one of zinc acetate and zinc nitrate.

[0019] Furthermore, the sodium salt in step (3) is any one of sodium oxalate, sodium sulfate, and sodium chloride. The addition of the sodium salt helps to adjust the viscosity and other properties of the solvent, helps to reduce the diameter of the nanorods, and increases the specific surface area, thereby improving the catalytic performance of the final product.

[0020] Furthermore, after the suspension B is transferred to the reactor in step (4), the filling degree of the suspension B in the reactor is 80%.

[0021] Furthermore, in steps (5) and (8), the method for washing the obtained solid precipitate is: washing the obtained solid precipitate alternately with deionized water and anhydrous ethanol for 3 to 5 times.

[0022] Furthermore, during the calcination in step (8), the holding temperature is 350-400°C, the heating rate is 3-5°C / min, and the holding time is 1-2 hours. If the calcination temperature is too high, the surface adsorption properties of the ZnWO4 nanorods will be affected, thereby affecting the catalytic performance; if the calcination temperature is too low, CeO2 will not be generated.

[0023] Furthermore, the ZnWO4 / CeO2 nanocomposite material prepared according to the above method contains two phases, ZnWO4 and CeO2, and the mass fraction of CeO2 in the ZnWO4 / CeO2 nanocomposite material is 1-10%. The ZnWO4 is rod-shaped with a diameter of 20-40 nm, and CeO2 nanoparticles with a diameter of 3-10 nm are attached to the surface of the ZnWO4 nanorods.

[0024] The present invention also provides an application of the ZnWO4 / CeO2 nanocomposite material obtained according to the above preparation method in the degradation of organic pollutants under the synergistic action of visible light / ultrasound, especially in the degradation of rhodamine B. The degradation rate of rhodamine B under the synergistic action of visible light / ultrasound reaches about 96%, which is much higher than the degradation rate of rhodamine B under the synergistic action of single-phase ZnWO4 nanopowder, indicating that compared with single-phase ZnWO4, the ZnWO4 / CeO2 nanocomposite material significantly improves the degradation effect of organic pollutants.

[0025] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention can achieve considerable technological advancement and practicality, and has a wide range of utilization value. It has at least the following advantages:

[0026] (1) The present invention adopts a two-step synthesis method. First, zinc tungstate nanopowder is prepared. Then, the zinc tungstate nanopowder is mixed with cerium nitrate solution, urea is added, the pH is adjusted, and then centrifugation is performed. The product is dried and calcined. The resulting zinc tungstate / cerium oxide nanocomposite material contains two phases, ZnWO4 and CeO2. The ZnWO4 is a rod-shaped structure with a diameter of 20 to 40 nm. CeO2 nanoparticles with a diameter of 3 to 10 nm are attached to the surface of the ZnWO4 nanorods. The zinc tungstate / cerium oxide ultrasound-visible light composite catalyst prepared by the present invention was tested for the photocatalytic degradation of rhodamine B solution under ultrasound / visible light synergistic radiation, showing excellent catalytic oxidation performance.

[0027] (2) The synthesis process of the present invention is simple and easy to operate. The product synthesized by the reaction is of high purity. It has excellent catalytic performance against organic pollutants under the synergistic effect of ultrasound / visible light, filling the gap in the field of ZnWO4 / CeO2 synthesis technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The XRD pattern of the ZnWO4 / CeO2 nanocomposite material prepared in Example 1;

[0029] Figure 2 is a HRTEM image of the ZnWO4 / CeO2 nanocomposite material prepared in Example 1;

[0030] Figure 3 This is a comparison chart of the catalytic results of the ZnWO4 / CeO2 nanocomposite material prepared in Example 1 and the ZnWO4 nanopowder under different test conditions. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] Example 1:

[0033] (1) Weigh a certain amount of Na2WO4·2H2O and dissolve it in a solvent. After sufficient stirring and dissolution, a Na2WO4 solution with a concentration of 2.5 mol / L is obtained. The solvent is a mixture of deionized water and anhydrous ethanol with a volume ratio of 5:1. A certain amount of cetyltrimethylammonium bromide (CTAB) is added to the Na2WO4 solution and stirred uniformly to obtain a solution A. The mass fraction of CTAB in the solution A is 0.1%, which is set aside.

[0034] (2) Weigh a certain amount of zinc acetate and dissolve it in a solvent. After sufficient stirring and dissolution, a zinc ion solution with a concentration of 2.5 mol / L is obtained, which is referred to as solution B and set aside. The solvent in this step is a mixture of deionized water and anhydrous ethanol in a volume ratio of 5:1.

[0035] (3) Weigh a certain amount of sodium oxalate and dissolve it in a solvent. After thorough stirring and dissolution, a sodium ion solution with a concentration of 0.5 mol / L is obtained, which is referred to as solution C and set aside. The solvent in this step is a mixture of deionized water and anhydrous ethanol in a volume ratio of 5:1.

[0036] (4) Take 1 part of the solution A prepared in step (1) and 1 part of the solution B prepared in step (2) by volume, add the measured solution B to the solution A at a drop rate of 2 mL / min under stirring, and stir thoroughly to obtain suspension A. Take 1 part of the solution C by volume and add it to the suspension A. Continue stirring for 30 minutes to obtain suspension B. Transfer the obtained suspension B to a reactor. The filling degree of the suspension B in the reactor is 80%. Place the reactor in a muffle furnace and keep it warm at 150° C. for 16 hours. After the reaction is completed, cool the reactor to room temperature to obtain a solvent thermal product.

[0037] (5) transferring the solvent thermal product obtained in step (4) to a high-speed centrifuge for centrifugal separation, taking a solid precipitate, and washing the obtained solid precipitate alternately with deionized water and anhydrous ethanol for 3 to 5 times, then placing the washed solid product in a drying oven and drying it at 70° C. for 12 hours to obtain ZnWO4 nanopowder;

[0038] (6) Weigh a certain amount of Ce(NO3)3·6H2O and dissolve it in deionized water. After sufficient stirring, obtain a cerium nitrate solution with a concentration of 0.2 mol / L. Add a certain amount of ZnWO4 nanopowder prepared in step (5) to the cerium nitrate solution so that the content of ZnWO4 nanopowder in the cerium nitrate solution is 97.5%. Stir and mix thoroughly to obtain suspension C.

[0039] (7) Urea was dissolved in deionized water to form a 0.2 mol / L solution, and an equal volume of urea solution was added to the suspension C obtained in step (6) (the volume ratio of urea solution to suspension C was 1:1) at a dropwise rate of 4 mL / min. The pH value was then adjusted to 11 with 25 wt% ammonia water, and stirring was continued for 2 h.

[0040] (8) The product obtained in step (7) is centrifuged in a high-speed centrifuge, and the solid precipitate is taken, and the solid precipitate is washed alternately with deionized water and anhydrous ethanol for 3 to 5 times, and then the washed solid product is placed in a drying oven and dried at 90°C for 12 hours; the dried product is placed in a muffle furnace and calcined at a heating rate of 3°C / min, the holding temperature during calcination is 360°C, the holding time is 2 hours, and then cooled to room temperature to obtain a ZnWO4 / CeO2 nanocomposite material with a 1D / 0D structure.

[0041] The ZnWO4 / CeO2 nanocomposite material obtained in this embodiment was subjected to XRD and TEM tests. The test results are as follows: Figure 1 and Figure 2 As shown by Figure 1 and Figure 2 It can be seen that the synthesized product ZnWO4 / CeO2 nanocomposite material contains two phases, ZnWO4 and CeO2, and the mass fraction of CeO2 in the synthesized product is 2.5%. ZnWO4 is rod-shaped with a diameter of 20-40nm. CeO2 nanoparticles with a diameter of 3-5nm are attached to the surface of ZnWO4 nanorods.

[0042] The catalytic performance test of the synthesized product was carried out. 0.05g ZnWO4 nanopowder (control group) and the ZnWO4 / CeO2 nanocomposite material synthesized in this embodiment (test group) were taken as catalysts. Rhodamine B was used as the target degradation product. The concentration of the Rhodamine B solution was 7mg / L and the volume was 50mL. A 120W fluorescent tube was used as the light source. The distance between the sample and the tube was 15cm. Ultrasonic radiation was applied at the same time. The power of the ultrasonic wave was 80W and the frequency was 40Hz. The photocatalytic degradation experiment was carried out. After 80min of illumination, the results were as follows. Figure 3 As shown, Figure 3 In the data, ZWO-L refers to the degradation experiment of the control group samples under visible light conditions; ZWO-U refers to the degradation experiment of the control group samples under ultrasound conditions; ZWO-U+L refers to the degradation experiment of the control group samples under visible light / ultrasound synergistic radiation; ZWO-CeO2-L refers to the degradation experiment of the test group samples under visible light conditions; ZWO-CeO2-U refers to the degradation experiment of the test group samples under ultrasound conditions; ZWO-CeO2-U+L refers to the degradation experiment of the test group samples under visible light / ultrasound synergistic radiation. Figure 3 The results showed that when ZnWO4 was used to degrade Rhodamine B (RhB) under visible light irradiation, the degradation rate was only about 7%. Under the synergistic action of visible light and ultrasound, the degradation rate of ZnWO4 was about 47.8%. In contrast, the degradation rate of ZnWO4 / CeO2 nanocomposite under the synergistic action of visible light and ultrasound was about 96%. The comparison of the degradation effects showed that the ZnWO4 / CeO2 nanocomposite exhibited excellent ultrasound / visible light catalytic performance.

[0043] Example 2:

[0044] (1) Weigh a certain amount of Na2WO4·2H2O and dissolve it in a solvent. After sufficient stirring and dissolution, a Na2WO4 solution with a concentration of 2.5 mol / L is obtained. The solvent is a mixture of deionized water and anhydrous ethanol with a volume ratio of 6:1. A certain amount of cetyltrimethylammonium bromide (CTAB) is added to the Na2WO4 solution and stirred uniformly to obtain a solution A. The mass fraction of CTAB in the solution A is 0.1%, which is set aside.

[0045] (2) Weigh a certain amount of zinc acetate and dissolve it in a solvent. After sufficient stirring and dissolution, a zinc ion solution with a concentration of 2.5 mol / L is obtained, which is referred to as solution B and set aside. The solvent in this step is a mixture of deionized water and anhydrous ethanol in a volume ratio of 6:1.

[0046] (3) Weigh a certain amount of sodium sulfate and dissolve it in a solvent. After thorough stirring and dissolution, a sodium ion solution with a concentration of 0.5 mol / L is obtained, which is referred to as solution C and set aside. The solvent in this step is a mixture of deionized water and anhydrous ethanol in a volume ratio of 6:1.

[0047] (4) Take 1 part of the solution A prepared in step (1) and 1 part of the solution B prepared in step (2) by volume, add the measured solution B to the solution A at a drop rate of 2.5 mL / min under stirring, and stir thoroughly to obtain suspension A. Take 1 part of the solution C by volume and add it to the suspension A. Continue stirring for 30 minutes to obtain suspension B. Transfer the obtained suspension B to a reactor. The filling degree of the suspension B in the reactor is 80%. Place the reactor in a muffle furnace and keep it warm at 150°C for 18 hours. After the reaction is completed, cool the reactor to room temperature to obtain a solvent thermal product.

[0048] (5) transferring the solvent thermal product obtained in step (4) to a high-speed centrifuge for centrifugal separation, taking a solid precipitate, and washing the obtained solid precipitate alternately with deionized water and anhydrous ethanol for 3 to 5 times, then placing the washed solid product in a drying oven and drying it at 70° C. for 12 hours to obtain ZnWO4 nanopowder;

[0049] (6) Weigh a certain amount of Ce(NO3)3·6H2O and dissolve it in deionized water. After sufficient stirring, obtain a cerium nitrate solution with a concentration of 0.2 mol / L. Add a certain amount of ZnWO4 nanopowder prepared in step (5) to the cerium nitrate solution so that the content of ZnWO4 nanopowder in the cerium nitrate solution is 98.5%. Stir and mix thoroughly to obtain suspension C.

[0050] (7) Urea was dissolved in deionized water to form a 0.2 mol / L solution, and an equal volume of urea solution was added to the suspension C obtained in step (6) (the volume ratio of urea solution to suspension C was 1:1) at a dropwise addition rate of 4.5 mL / min. The pH value was then adjusted to 11.5 with 25 wt% ammonia water, and stirring was continued for 2 h.

[0051] (8) The product obtained in step (7) is centrifuged in a high-speed centrifuge, and the solid precipitate is taken, and the solid precipitate is washed alternately with deionized water and anhydrous ethanol for 3 to 5 times, and then the washed solid product is placed in a drying oven and dried at 95° C. for 12 hours; the dried product is placed in a muffle furnace and calcined at a heating rate of 3° C. / min, and the holding temperature during calcination is 380° C. for 2 hours, and then cooled to room temperature to obtain a ZnWO4 / CeO2 nanocomposite material with a 1D / 0D structure.

[0052] The ZnWO4 / CeO2 nanocomposite material obtained in this embodiment was subjected to XRD and TEM tests. The test results show that the synthetic product contains two phases, ZnWO4 and CeO2, with the mass fraction of CeO2 in the synthetic product being 1.5%. The ZnWO4 is rod-shaped with a diameter of 20 to 40 nm, and CeO2 nanoparticles with a diameter of 4 to 6 nm are attached to the surface of the ZnWO4 rods.

[0053] Example 3:

[0054] (1) Weigh a certain amount of Na2WO4·2H2O and dissolve it in a solvent. After sufficient stirring and dissolution, a Na2WO4 solution with a concentration of 2.5 mol / L is obtained. The solvent is a mixture of deionized water and anhydrous ethanol with a volume ratio of 5:1. A certain amount of cetyltrimethylammonium bromide (CTAB) is added to the Na2WO4 solution and stirred uniformly to obtain a solution A. The mass fraction of CTAB in the solution A is 0.12%, which is set aside.

[0055] (2) Weigh a certain amount of zinc acetate and dissolve it in a solvent. After sufficient stirring and dissolution, a zinc ion solution with a concentration of 2.5 mol / L is obtained, which is referred to as solution B and set aside. The solvent in this step is a mixture of deionized water and anhydrous ethanol in a volume ratio of 5:1.

[0056] (3) Weigh a certain amount of sodium oxalate and dissolve it in a solvent. After thorough stirring and dissolution, a sodium ion solution with a concentration of 0.5 mol / L is obtained, which is referred to as solution C and set aside. The solvent in this step is a mixture of deionized water and anhydrous ethanol in a volume ratio of 5:1.

[0057] (4) Take 1 part of the solution A prepared in step (1) and 1 part of the solution B prepared in step (2) by volume, add the measured solution B to the solution A at a drop rate of 3 mL / min under stirring, and stir thoroughly to obtain suspension A. Take 1 part of the solution C by volume and add it to the suspension A. Continue stirring for 30 minutes to obtain suspension B. Transfer the obtained suspension B to a reactor. The filling degree of the suspension B in the reactor is 80%. Place the reactor in a muffle furnace and keep it warm at 150° C. for 21 hours. After the reaction is completed, cool the reactor to room temperature to obtain a solvent thermal product.

[0058] (5) transferring the solvent thermal product obtained in step (4) to a high-speed centrifuge for centrifugal separation, taking a solid precipitate, and washing the obtained solid precipitate alternately with deionized water and anhydrous ethanol for 3 to 5 times, then placing the washed solid product in a drying oven and drying it at 80° C. for 10 hours to obtain ZnWO4 nanopowder;

[0059] (6) Weigh a certain amount of Ce(NO3)3·6H2O and dissolve it in deionized water. After sufficient stirring, obtain a cerium nitrate solution with a concentration of 0.2 mol / L. Add a certain amount of ZnWO4 nanopowder prepared in step (5) to the cerium nitrate solution so that the content of ZnWO4 nanopowder in the cerium nitrate solution is 96.5%. Stir and mix thoroughly to obtain suspension C.

[0060] (7) Urea was dissolved in deionized water to form a 0.2 mol / L solution, and an equal volume of urea solution was added to the suspension C obtained in step (6) (the volume ratio of urea solution to suspension C was 1:1) at a dropwise rate of 5 mL / min. The pH value was then adjusted to 11.8 with 25 wt% ammonia water, and stirring was continued for 2 h.

[0061] (8) the product obtained in step (7) is subjected to centrifugal separation by a high-speed centrifuge, the solid precipitate is taken, and the obtained solid precipitate is alternately washed 3-5 times with deionized water and anhydrous ethanol in sequence, and then the washed solid product is placed into a drying oven and dried at 100°C for 10h; the dried product is placed into a muffle furnace, the heating rate is 3°C / min, the holding temperature during calcination is 390°C, and the holding time is 2h, and then the product is cooled to room temperature to obtain a ZnWO4 / CeO2 nanocomposite with 1D / 0D structure.

[0062] The ZnWO4 / CeO2 nanocomposite obtained in this example is subjected to XRD and TEM tests, and the test results show that the synthetic product contains two phases of ZnWO4 and CeO2, the mass fraction of CeO2 in the synthetic product is 3.5%, ZnWO4 is rod-shaped, the diameter is 20-40nm, and CeO2 nanoparticles with a diameter of 4-7nm grow on the surface of the ZnWO4 rod.

[0063] Example 4:

[0064] (1) A certain amount of Na2WO4·2H2O is dissolved in a solvent, after being fully stirred and dissolved, a Na2WO4 solution with a concentration of 2.5mol / L is obtained, wherein the solvent is a mixture of deionized water and anhydrous ethanol with a volume ratio of 6:1; a certain amount of cetyltrimethylammonium bromide (CTAB) is added to the Na2WO4 solution, stirred uniformly, and an A solution is obtained, the mass fraction of CTAB in the A solution is 0.15%, and the A solution is reserved;

[0065] (2) A certain amount of zinc acetate is dissolved in a solvent, after being fully stirred and dissolved, a zinc ion solution with a concentration of 2.5mol / L is obtained, which is recorded as B solution, and the B solution is reserved; the solvent used in this step is a mixture of deionized water and anhydrous ethanol with a volume ratio of 7:1;

[0066] (3) A certain amount of sodium chloride is dissolved in a solvent, after being fully stirred and dissolved, a sodium ion solution with a concentration of 0.5mol / L is obtained, which is recorded as C solution, and the C solution is reserved; the solvent used in this step is a mixture of deionized water and anhydrous ethanol with a volume ratio of 7:1;

[0067] (4) Take 1 part of the solution A prepared in step (1) and 1 part of the solution B prepared in step (2) by volume, add the measured solution B to the solution A at a drop rate of 2.8 mL / min under stirring, and stir thoroughly to obtain a suspension A. Take 1 part of the solution C by volume and add it to the suspension A. Continue stirring for 30 minutes to obtain a suspension B. Transfer the obtained suspension B to a reactor. The filling degree of the suspension B in the reactor is 80%. Place the reactor in a muffle furnace and keep it warm at 150° C. for 22 hours. After the reaction is completed, cool the reactor to room temperature to obtain a solvent thermal product.

[0068] (5) transferring the solvent thermal product obtained in step (4) to a high-speed centrifuge for centrifugal separation, taking a solid precipitate, and washing the obtained solid precipitate alternately with deionized water and anhydrous ethanol for 3 to 5 times, then placing the washed solid product in a drying oven and drying it at 80° C. for 11 hours to obtain ZnWO4 nanopowder;

[0069] (6) Weigh a certain amount of Ce(NO3)3·6H2O and dissolve it in deionized water. After sufficient stirring, obtain a cerium nitrate solution with a concentration of 0.2 mol / L. Add a certain amount of ZnWO4 nanopowder prepared in step (5) to the cerium nitrate solution so that the content of ZnWO4 nanopowder in the cerium nitrate solution is 95%, and stir and mix thoroughly to obtain suspension C.

[0070] (7) Urea was dissolved in deionized water to form a 0.2 mol / L solution, and an equal volume of urea solution was added to the suspension C obtained in step (6) (the volume ratio of urea solution to suspension C was 1:1) at a dropwise addition rate of 5.5 mL / min. The pH value was then adjusted to 11.3 with 25 wt% ammonia water, and stirring was continued for 2 h.

[0071] (8) The product obtained in step (7) is centrifuged in a high-speed centrifuge, and the solid precipitate is taken, and the solid precipitate is washed alternately with deionized water and anhydrous ethanol for 3 to 5 times, and then the washed solid product is placed in a drying oven and dried at 98° C. for 10 hours; the dried product is placed in a muffle furnace and calcined at a heating rate of 4° C. / min, the holding temperature during calcination is 390° C., the holding time is 1.5 hours, and then cooled to room temperature to obtain a ZnWO4 / CeO2 nanocomposite material with a 1D / 0D structure.

[0072] The ZnWO4 / CeO2 nanocomposite material obtained in this embodiment was subjected to XRD and TEM tests. The test results show that the synthetic product contains two phases, ZnWO4 and CeO2, with the mass fraction of CeO2 in the synthetic product being 5%. The ZnWO4 is rod-shaped with a diameter of 20 to 40 nm, and CeO2 nanoparticles with a diameter of 3 to 6 nm are attached to the surface of the ZnWO4 rods.

[0073] Example 5:

[0074] (1) Weigh a certain amount of Na2WO4·2H2O and dissolve it in a solvent. After sufficient stirring and dissolution, a Na2WO4 solution with a concentration of 2.5 mol / L is obtained. The solvent is a mixture of deionized water and anhydrous ethanol with a volume ratio of 7:1. Add a certain amount of cetyltrimethylammonium bromide (CTAB) to the Na2WO4 solution and stir evenly to obtain a solution A. The mass fraction of CTAB in the solution A is 0.14%, which is set aside.

[0075] (2) Weigh a certain amount of zinc nitrate and dissolve it in a solvent. After sufficient stirring and dissolution, a zinc ion solution with a concentration of 2.5 mol / L is obtained, which is referred to as solution B and set aside. The solvent in this step is a mixture of deionized water and anhydrous ethanol in a volume ratio of 7:1.

[0076] (3) Weigh a certain amount of sodium oxalate and dissolve it in a solvent. After thorough stirring and dissolution, a sodium ion solution with a concentration of 0.5 mol / L is obtained, which is referred to as solution C and set aside. The solvent in this step is a mixture of deionized water and anhydrous ethanol in a volume ratio of 5:1.

[0077] (4) Take 1 part of the solution A prepared in step (1) and 1 part of the solution B prepared in step (2) by volume, add the measured solution B to the solution A at a drop rate of 3 mL / min under stirring, and stir thoroughly to obtain suspension A. Take 1 part of the solution C by volume and add it to the suspension A. Continue stirring for 30 minutes to obtain suspension B. Transfer the obtained suspension B to a reactor. The filling degree of the suspension B in the reactor is 80%. Place the reactor in a muffle furnace and keep it warm at 150° C. for 19 hours. After the reaction is completed, cool the reactor to room temperature to obtain a solvent thermal product.

[0078] (5) transferring the solvent thermal product obtained in step (4) to a high-speed centrifuge for centrifugal separation, taking a solid precipitate, and washing the obtained solid precipitate alternately with deionized water and anhydrous ethanol for 3 to 5 times, then placing the washed solid product in a drying oven and drying it at 78° C. for 12 hours to obtain ZnWO4 nanopowder;

[0079] (6) Weigh a certain amount of Ce(NO3)3·6H2O and dissolve it in deionized water. After sufficient stirring, obtain a cerium nitrate solution with a concentration of 0.2 mol / L. Add a certain amount of ZnWO4 nanopowder prepared in step (5) to the cerium nitrate solution so that the content of ZnWO4 nanopowder in the cerium nitrate solution is 95%, and stir and mix thoroughly to obtain suspension C.

[0080] (7) Urea was dissolved in deionized water to form a 0.2 mol / L solution, and an equal volume of urea solution was added to the suspension C obtained in step (6) (the volume ratio of urea solution to suspension C was 1:1) at a dropwise rate of 6 mL / min. The pH value was then adjusted to 12 with 25 wt% ammonia water, and stirring was continued for 2 h.

[0081] (8) The product obtained in step (7) is centrifuged in a high-speed centrifuge, and the solid precipitate is taken, and the solid precipitate is washed alternately with deionized water and anhydrous ethanol for 3 to 5 times, and then the washed solid product is placed in a drying oven and dried at 92° C. for 12 hours; the dried product is placed in a muffle furnace and calcined at a heating rate of 4° C. / min, the holding temperature during calcination is 400° C., the holding time is 1.5 hours, and then cooled to room temperature to obtain a ZnWO4 / CeO2 nanocomposite material with a 1D / 0D structure.

[0082] The ZnWO4 / CeO2 nanocomposite material obtained in this embodiment was subjected to XRD and TEM tests. The test results show that the synthetic product contains two phases, ZnWO4 and CeO2, with the mass fraction of CeO2 in the synthetic product being 5%. The ZnWO4 is rod-shaped with a diameter of 20 to 40 nm, and CeO2 nanoparticles with a diameter of 6 to 10 nm are attached to the surface of the ZnWO4 rods.

[0083] The above description is merely an embodiment of the present invention and does not constitute any form of limitation to the present invention. The present invention may also have other forms of embodiments based on the above structures and functions, which are not listed here one by one. Therefore, any simple modification, equivalent changes, and modifications made to the above embodiments by any person skilled in the art in accordance with the technical essence of the present invention without departing from the scope of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A cerium oxide nanoparticle modified zinc tungstate nanorod ultrasound-visible light composite catalyst, characterized in that The composite catalyst comprises ZnWO4 and CeO2 phases, wherein the mass fraction of CeO2 in the composite catalyst is 1-10%. The ZnWO4 is rod-shaped with a diameter of 20-40 nm, and CeO2 nanoparticles with a diameter of 3-10 nm are attached to and grown on the surface of the ZnWO4 nanorods. The cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst is prepared according to the following method: (1) Weigh a certain amount of Na2WO4·2H2O and dissolve it in a solvent. After sufficient stirring and dissolution, obtain a Na2WO4 solution with a concentration of 2.5 mol / L. Add hexadecyltrimethylammonium bromide to the Na2WO4 solution and stir evenly to obtain solution A for later use. The solvent is a mixture of deionized water and anhydrous ethanol. The volume ratio of deionized water to anhydrous ethanol is (5-7):

1. The mass fraction of hexadecyltrimethylammonium bromide in solution A is 0.1-0.15%. (2) Weigh a certain amount of zinc salt and dissolve it in a solvent. After sufficient stirring and dissolution, a zinc ion solution with a concentration of 2.5 mol / L is obtained, which is recorded as solution B and set aside. The solvent is a mixture of deionized water and anhydrous ethanol, and the volume ratio of deionized water to anhydrous ethanol is (5-7):1; (3) Weigh a certain amount of sodium salt and dissolve it in a solvent. After sufficient stirring and dissolution, a sodium ion solution with a concentration of 0.5 mol / L is obtained, which is recorded as solution C and set aside. The sodium salt is any one of sodium oxalate, sodium sulfate, and sodium chloride. (4) Take 1 part of the solution A prepared in step (1) and 1 part of the solution B prepared in step (2) by volume, add the measured solution B to the solution A at a drop rate of 2-4 mL / min under stirring, and obtain suspension A after sufficient stirring; take 1 part of the solution C by volume and add it to the suspension A, continue stirring for 30 min to obtain suspension B, transfer the obtained suspension B to a reactor, place the reactor in a muffle furnace and keep it at 150 ° C for 16-22 h, then cool the reactor to room temperature to obtain a solvent thermal product; (5) The solvent thermal product obtained in step (4) is transferred to a high-speed centrifuge for centrifugal separation, the solid precipitate obtained is washed, and the washed solid product is placed in a drying oven and dried at 70-80 ° C for 10-12 hours to obtain ZnWO4 nanopowder; (6) Weigh a certain amount of Ce(NO3)3·6H2O and dissolve it in deionized water. After sufficient stirring, obtain a cerium nitrate solution with a concentration of 0.2 mol / L. Add a certain amount of ZnWO4 nanopowder prepared in step (5) to the cerium nitrate solution, stir and mix thoroughly to obtain suspension C. (7) Dissolve urea in deionized water to form a 0.2 mol / L urea solution, add the urea solution to the suspension C obtained in step (6) at a dropwise rate of 4-6 mL / min, and the volume ratio of urea solution to suspension C is 1:

1. Then adjust the pH value to 11-12 with 25% ammonia water, and continue stirring for 2 h. (8) The product obtained in step (7) is centrifuged in a high-speed centrifuge, and the obtained solid precipitate is washed. The washed solid product is then placed in a drying oven and dried at 80-100°C for 10-12 h; the dried product is placed in a muffle furnace for calcination, and then cooled to room temperature to obtain a ZnWO4 / CeO2 nanocomposite material.

2. A method for preparing a cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst, characterized in that The following steps are involved: (1) Weigh a certain amount of Na2WO4·2H2O and dissolve it in a solvent. After sufficient stirring and dissolution, obtain a Na2WO4 solution with a concentration of 2.5 mol / L. Add hexadecyltrimethylammonium bromide to the Na2WO4 solution and stir evenly to obtain solution A for later use. The solvent is a mixture of deionized water and anhydrous ethanol. The volume ratio of deionized water to anhydrous ethanol is (5-7):

1. The mass fraction of hexadecyltrimethylammonium bromide in solution A is 0.1-0.15%. (2) Weigh a certain amount of zinc salt and dissolve it in a solvent. After sufficient stirring and dissolution, a zinc ion solution with a concentration of 2.5 mol / L is obtained, which is recorded as solution B and set aside. The solvent is a mixture of deionized water and anhydrous ethanol, and the volume ratio of deionized water to anhydrous ethanol is (5-7):1; (3) Weigh a certain amount of sodium salt and dissolve it in a solvent. After sufficient stirring and dissolution, a sodium ion solution with a concentration of 0.5 mol / L is obtained, which is recorded as solution C and set aside. The sodium salt is any one of sodium oxalate, sodium sulfate, and sodium chloride. (4) Take 1 part of the solution A prepared in step (1) and 1 part of the solution B prepared in step (2) by volume, add the measured solution B to the solution A at a drop rate of 2-4 mL / min under stirring, and obtain suspension A after sufficient stirring; take 1 part of the solution C by volume and add it to the suspension A, continue stirring for 30 min to obtain suspension B, transfer the obtained suspension B to a reactor, place the reactor in a muffle furnace and keep it at 150 ° C for 16-22 h, then cool the reactor to room temperature to obtain a solvent thermal product; (5) The solvent thermal product obtained in step (4) is transferred to a high-speed centrifuge for centrifugal separation, the solid precipitate obtained is washed, and the washed solid product is placed in a drying oven and dried at 70-80 ° C for 10-12 hours to obtain ZnWO4 nanopowder; (6) Weigh a certain amount of Ce(NO3)3·6H2O and dissolve it in deionized water. After sufficient stirring, obtain a cerium nitrate solution with a concentration of 0.2 mol / L. Add a certain amount of ZnWO4 nanopowder prepared in step (5) to the cerium nitrate solution, stir and mix thoroughly to obtain suspension C. (7) Dissolve urea in deionized water to form a 0.2 mol / L urea solution, add the urea solution to the suspension C obtained in step (6) at a dropwise rate of 4-6 mL / min, and the volume ratio of urea solution to suspension C is 1:

1. Then adjust the pH value to 11-12 with 25% ammonia water, and continue stirring for 2 h. (8) The product obtained in step (7) is centrifuged in a high-speed centrifuge, and the obtained solid precipitate is washed. The washed solid product is then placed in a drying oven and dried at 80-100°C for 10-12 h; the dried product is placed in a muffle furnace for calcination, and then cooled to room temperature to obtain a ZnWO4 / CeO2 nanocomposite material.

3. The method for preparing the cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst according to claim 2, characterized in that The zinc salt in step (2) is any one of zinc acetate and zinc nitrate.

4. The method for preparing the cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst according to claim 2, characterized in that After the suspension B is transferred to the reactor in step (4), the filling degree of the suspension B in the reactor is 80%.

5. The method for preparing the cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst according to claim 2, characterized in that In steps (5) and (8), the method for washing the obtained solid precipitate is: washing the obtained solid precipitate alternately with deionized water and anhydrous ethanol for 3 to 5 times.

6. The method for preparing the cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst according to claim 2, characterized in that During the calcination in step (8), the holding temperature is 350-400°C, the heating rate is 3-5°C / min, and the holding time is 1-2 h.

7. The method for preparing the cerium oxide nanoparticle-modified zinc tungstate nanorod ultrasound-visible light composite catalyst according to claim 2, characterized in that The prepared ZnWO4 / CeO2 nanocomposite material contains two phases, ZnWO4 and CeO2, with the mass fraction of CeO2 in the ZnWO4 / CeO2 nanocomposite material being 1-10%. The ZnWO4 is rod-shaped with a diameter of 20-40 nm, and CeO2 nanoparticles with a diameter of 3-10 nm are attached to the surface of the ZnWO4 nanorods.

8. Use of the ZnWO4 / CeO2 nanocomposite material obtained by the preparation method according to claim 2 in the degradation of organic pollutants under the synergistic action of visible light / ultrasound.

Images