Fe2O3-La2O3-Rh2O3@HNi x S composite material, preparation method and application in wastewater treatment

Abstract

The invention discloses a Fe2O3-La2O3-Rh2O3@HNi x S composite material, preparation method and application in wastewater treatment belong to the field of wastewater treatment technology. The technical scheme includes: 1) removing the oxide layer on the surface of the nickel mesh with dilute acid; 2) growing Ni2O nanoparticles on the surface of the nickel mesh; 3) placing in sodium sulfide solution, stirring, and obtaining a sample Ni with a black surface. x S‑nm; 4) Ni x S‑nm was placed in a dilute acid solution and etched to obtain a sample containing HNi x S-nm mixed solution, adding Fe(NO3)3·9H2O, Rh(NO3)3·2H2O and La(NO3)3·6H2O solid particles to the mixed solution and stirring; 5) adding a precipitant, precipitating at room temperature, filtering, washing, drying, calcining, and obtaining a composite material. The composite material of the present invention is used for treating pyruvic acid in wastewater and has the characteristics of high activity and easy recovery.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment and specifically relates to a Fe2O3-La2O3-Rh2O3@HNi x S composite material, preparation method and application in wastewater treatment. Background Art

[0002] With the development of industrialization, the discharge of industrial wastewater has increased year by year, which contains a large number of toxic and harmful substances and its composition is extremely complex. The organic pollutants, heavy metal ions, acid-base substances, etc. in these wastewaters pose a serious threat to the environment. Pyruvic acid is an organic acid, which exists in various forms in wastewater, including free state, bound state or derivatives, which increases the difficulty of treatment. As a common organic acid, pyruvic acid mainly comes from chemical, pharmaceutical and food processing industries. In the production process of these industries, pyruvic acid is often discharged into wastewater as an intermediate or by-product. The hazards of pyruvic acid cannot be ignored: it is highly toxic to aquatic organisms, can cause the death of aquatic organisms such as fish, and destroy the ecological balance of water bodies; pyruvic acid also has a certain environmental hormone effect, which may have adverse effects on the reproductive system of humans and animals; in addition, pyruvic acid is highly corrosive and may cause damage to drainage pipes, equipment, etc. Therefore, it is necessary to treat pyruvic acid in wastewater to reduce its hazards.

[0003] Semiconductor materials have shown extremely high application value in the field of photocatalysis due to their unique electronic structure and photophysical properties. Photocatalytic technology uses electron-hole pairs generated by semiconductor materials under light to promote reactions such as degradation of environmental pollutants, water decomposition and CO2 reduction. It is a green and environmentally friendly catalytic technology. However, the light response range of traditional semiconductor materials is limited, which limits their application in the field of photocatalysis. Electroreduction treatment is an effective catalyst modification method. Through electroreduction treatment, it can form oxygen vacancies on the catalyst surface. As active centers, oxygen vacancies can effectively adsorb and activate pyruvic acid molecules, reduce the potential barrier of pyruvic acid reduction reaction, and thus improve the reaction activity of photocatalytic degradation of pyruvic acid. At the same time, electroreduction treatment causes a large number of protons to attach to the catalyst surface, which may participate in the catalytic reaction and further improve the performance of the catalyst. Despite this, the current catalysts still have problems such as low catalytic efficiency, unstable performance and difficulty in recycling and reuse. There is an urgent need for an efficient, environmentally friendly and economical wastewater treatment technology to solve the problem of treating organic pollutants such as pyruvic acid. Therefore, the development of new composite materials to treat pyruvic acid wastewater has a wide market demand and good development prospects. Summary of the invention

[0004] The present invention provides a Fe2O3-La2O3-Rh2O3@HNi xS (0<x<1) composite materials, preparation methods and applications in wastewater treatment, Fe2O3-La2O3-Rh2O3@HNi x The S (0<x<1) composite material is used to treat pyruvic acid in wastewater and has the characteristics of high activity and easy recovery.

[0005] The technical solution of the present invention is:

[0006] In the first aspect, Fe2O3-La2O3-Rh2O3@HNi x The preparation method of the S (0<x<1) composite material comprises the following steps:

[0007] 1) Use dilute acid to remove the oxide layer on the surface of the nickel mesh, rinse the nickel mesh, and dry it;

[0008] 2) Ni2O nanoparticles were grown on the surface of the nickel mesh by electrodeposition. The electrolyte was a mixture of NiSO4 and citric acid. The pH value of the electrolyte was adjusted to 10-12. The temperature was 50-70°C and the deposition voltage was -(0.5-0.7)V. SAE The sample Ni2O-nm was obtained by deposition for 2-6 minutes. The small nickel oxide nanoparticles generated on the nickel mesh have a larger comparative area and can load the active components on its surface to a greater extent.

[0009] 3) Place the Ni2O-nm sample in a sodium sulfide solution and stir the reaction at 20-30°C for 20-40 minutes to obtain a black sample Ni x S-nm (0<x<1);

[0010] 4) Ni x S-nm (0<x<1) was placed in a dilute acid solution and etched at 70-90℃ for 110-130min to obtain a sample containing HNi x S-nm (0<x<1) mixed solution, add Fe(NO3)3·9H2O, Rh(NO3)3·2H2O and La(NO3)3·6H2O solid particles to the mixed solution and stir for 1.5-2.5h to mix evenly;

[0011] 5) Add precipitant, stir at 80-100℃ for 8-12h, precipitate at room temperature for 12-24h, filter, wash, dry at 60-100℃ for 8-16h, and then calcine in a tube furnace under an inert gas atmosphere to obtain Fe2O3-La2O3-Rh2O3@HNi x S (0<x<1) composite material.

[0012] Preferably, the acid in step 1) is hydrochloric acid or acetic acid.

[0013] Preferably, in step 2), the working electrode is a nickel mesh, the counter electrode is a platinum plate, and the reference electrode is a silver electrode.

[0014] Preferably, in step 2), the pH is adjusted by using one of ammonia water, sodium hydroxide solution and potassium hydroxide solution with a mass concentration of 25%.

[0015] Preferably, the dilute acid in step 4) is dilute hydrochloric acid or dilute acetic acid.

[0016] Preferably, in step 5), the precipitant is thiourea or urea, the inert gas is argon or helium, the calcination temperature is 550-700° C., and the calcination time is 3-6 hours.

[0017] Preferably, the mass ratio of NiSO4 and citric acid in step 2) is (2-6):(3-5), and the concentration of the sodium sulfide solution in step 3) is 0.08-0.2 mol / L.

[0018] Preferably, in step 4), the mass ratio of Fe(NO3)3·9H2O, Rh(NO3)3·2H2O and La(NO3)3·6H2O is (4-6):(3-4):(3-4), and the ratio of the sum of the masses of Fe(NO3)3·9H2O, Rh(NO3)3·2H2O and La(NO3)3·6H2O to the mass of the precipitant is (55-65):1.

[0019] In the second aspect, the Fe2O3-La2O3-Rh2O3@HNi prepared by the preparation method is disclosed. x S (0<x<1) composite material.

[0020] In the third aspect, the Fe2O3-La2O3-Rh2O3@HNi x The application of S (0<x<1) composite material in photocatalytic degradation of pyruvic acid in wastewater includes the following steps:

[0021] A. Fe2O3-La2O3-Rh2O3@HNi x The S (0<x<1) composite material is placed in a liquid film photoreactor, and the set temperature of the liquid film photoreactor is 20-30°C and the pressure is 0.1-0.3MPa;

[0022] B. Add wastewater to the liquid film photoreactor, the volume of wastewater does not exceed Fe2O3-La2O3-Rh2O3@HNi x S (0<x<1) composite material nickel mesh, in dark conditions, argon gas is introduced into the liquid film photoreactor, the flow rate of argon gas is 50-100mL / min, and the introduction time of argon gas is 30-50min;

[0023] C. Measure the concentration of pyruvate under visible light after 2-4 hours of reaction.

[0024] The present invention constructs Fe2O3-La2O3-Rh2O3@HNi with a three-dimensional micro-nano structure on a nickel mesh. x As a catalyst, Fe2O3 has a suitable bandgap and good visible light absorption capacity. The introduction of La2O3 not only improves the structural stability of the composite material, but also adjusts the energy band position of Fe2O3 through its unique electronic structure, promoting the separation of photogenerated electron-hole pairs. At the same time, La2O3 also acts as a co-catalyst, providing additional active sites to accelerate surface catalytic reactions. Rh2O3 has good conductivity and catalytic activity. In the composite material, Rh2O3 acts as a "bridge" for electron transfer, accelerating the migration of photogenerated electrons from Fe2O3 to surface active sites, effectively reducing the recombination of electron-hole pairs and improving quantum efficiency. The synergistic effect of Fe2O3, La2O3 and Rh2O3 accelerates the separation and migration of photogenerated carriers. The synergistic effect of Fe2O3, La2O3 and Rh2O3 in constructing a pn heterojunction structure and sulfur vacancies provides abundant active sites, fast photogenerated electron-hole transfer and separation pathways for photocatalysis.

[0025] In HNi x In S, the structure of surface sulfur vacancies can adjust the band gap of the semiconductor and broaden the light response range. These defect states can capture a large number of localized electrons and inhibit the recombination of photogenerated carriers. In addition, as active sites for the adsorption and activation of reactants, they can reduce the activation energy barrier of thermodynamic reactions, thereby effectively improving the photocatalytic performance. Electroreduction treatment increases the number of sulfur vacancies on the composite material. These sulfur vacancies, as active centers, can effectively adsorb and activate pyruvate, reduce the barrier of pyruvate reduction reaction, and enhance the reaction activity of photocatalytic degradation of pyruvate; in addition, a large number of protons are attached to the surface of the composite material, which can participate in the catalytic reaction, further improving the catalytic performance of the composite material.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. Fe2O3-La2O3-Rh2O3@HNi of the present invention x As a new type of efficient catalyst, S (0 < x < 1) composite material shows significant advantages in treating pyruvic acid in wastewater. The composite material combines Fe2O3, La2O3, Rh2O3 and HNi xThe excellent performance of S (0<x<1) forms a composite structure with high catalytic activity. Through a specific preparation method, a composite material with stable performance and easy recycling can be prepared. Experimental studies have shown that the composite material has the advantages of high efficiency, environmental protection and economy in treating pyruvic acid in wastewater, and has broad application prospects.

[0028] 2. Fe2O3-La2O3-Rh2O3@HNi of the present invention x The S (0<x<1) composite material has a large number of protons and more pyruvic acid adsorption and activation sites attached to its surface, and has better catalytic activity.

[0029] 3. Fe2O3-La2O3-Rh2O3@HNi of the present invention x The method for preparing the S (0<x<1) composite material has a simple process, the prepared composite material can be reused, and has a good catalytic effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is Fe2O3-La2O3-Rh2O3@HNi prepared in Example 1 of the present invention 0.3 TEM image of S (0<x<1) composite material. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0032] Example 1

[0033] Fe2O3-La2O3-Rh2O3@HNi 0.3 The S composite material is composed of a nickel mesh and Fe2O3, La2O3, Rh2O3 and HNi attached to the nickel mesh. 0.3 S composition, Fe2O3, La2O3, Rh2O3 and HNi 0.3 The total amount of S loaded was 25% of the mass of the nickel mesh.

[0034] Fe2O3-La2O3-Rh2O3@HNi 0.3 The preparation method of the S composite material comprises the following steps:

[0035] 1) Soak in 0.1 mol / L dilute hydrochloric acid for 2 hours to remove the 4×4 cm 2 The oxide layer on the surface of the nickel mesh was then rinsed with deionized water three times and dried at 60 °C for 8 h;

[0036] 2) In a three-electrode battery system, Ni2O nanoparticles were grown on the surface of a nickel mesh by electrodeposition. 30 mg of NiSO4 and 45 mg of citric acid were added to 200 mL of deionized water. The pH value of the electrolyte was adjusted to 11 with 25% ammonia water. The working electrode was a nickel mesh, the counter electrode was a platinum plate, and the reference electrode was a silver electrode. The deposition voltage was -0.6 V at a temperature of 60 °C. SAE The sample Ni2O-nm was obtained after deposition for 4 min. The particle size of Ni2O nanoparticles on the sample Ni2O-nm was 20 nm.

[0037] 3) Place the Ni2O sample in a 0.2 mol / L sodium sulfide solution and stir at 25°C for 30 min to obtain a black Ni sample. 0.3 S-nm;

[0038] 4) Ni 0.3 S-nm was placed in a 0.1 mol / mL dilute hydrochloric acid solution and etched at 80°C for 120 min to obtain a sample containing HNi 0.3 S-nm mixed solution, add 400 mg of Fe(NO3)3·9H2O, 400 mg of Rh(NO3)3·2H2O and 300 mg of La(NO3)3·6H2O solid particles to the mixed solution and stir for 2 h to mix well;

[0039] 5) Add 20 mg of precipitant thiourea, stir at 90 ° C for 10 h, precipitate at room temperature for 18 h, filter, wash, dry at 80 ° C for 10 h, and calcine at 600 ° C in a tube furnace in an inert gas argon atmosphere for 5 h to obtain Fe2O3-La2O3-Rh2O3@HNi 0.3 S composite material.

[0040] The Fe2O3-La2O3-Rh2O3@HNi 0.3 The application of the S composite material in photocatalytic degradation of pyruvic acid in wastewater comprises the following steps:

[0041] A. Fe2O3-La2O3-Rh2O3@HNi 0.3 The S composite material was placed in a liquid film photoreactor, and the set temperature of the liquid film photoreactor was 25°C and the pressure was 0.1MPa;

[0042] B. Add wastewater to the liquid film photoreactor, the volume of wastewater does not exceed Fe2O3-La2O3-Rh2O3@HNi 0.3 S composite nickel mesh, argon was introduced into the liquid film photoreactor under dark conditions, the flow rate of argon was 70 mL / min, and the introduction time of argon was 40 min;

[0043] C. Under visible light irradiation, the light source is a 350W xenon lamp with a filter, and the concentration of pyruvate is measured after 3 hours of reaction.

[0044] Example 2

[0045] Fe2O3-La2O3-Rh2O3@HNi 0.4 The S composite material is composed of a nickel mesh and Fe2O3, La2O3, Rh2O3 and HNi attached to the nickel mesh. 0.4 S composition, Fe2O3, La2O3, Rh2O3 and HNi 0.4 The total amount of S loaded was 30% of the mass of the nickel mesh.

[0046] Fe2O3-La2O3-Rh2O3@HNi 0.4 The preparation method of the S composite material comprises the following steps:

[0047] 1) Soak in 0.1 mol / L dilute acetic acid for 2 hours to remove the 4×4 cm 2 The oxide layer on the surface of the nickel mesh was then rinsed with deionized water three times and dried at 60 °C for 8 h;

[0048] 2) In a three-electrode battery system, Ni2O nanoparticles were grown on the surface of a nickel mesh by electrodeposition. 30 mg of NiSO4 and 40 mg of citric acid were added to 200 mL of deionized water. The pH value of the electrolyte was adjusted to 10 with 0.1 mol / L sodium hydroxide solution. A nickel mesh was used as the working electrode, a platinum plate was used as the counter electrode, and a silver electrode was used as the reference electrode. The deposition voltage was -0.5 V at a temperature of 50 °C. SAE The sample Ni2O-nm was obtained after deposition for 6 min. The particle size of Ni2O nanoparticles on the sample Ni2O-nm was 30 nm.

[0049] 3) Place the Ni2O sample in a 0.1 mol / L sodium sulfide solution and stir at 20°C for 40 min to obtain a black Ni sample. 0.4 S-nm;

[0050] 4) Ni 0.4 S-nm was placed in a 0.1 mol / mL dilute hydrochloric acid solution and etched at 70°C for 130 min to obtain a sample containing HNi 0.4 S-nm mixed solution, add 500 mg of Fe(NO3)3·9H2O, 350 mg of Rh(NO3)3·2H2O and 350 mg of La(NO3)3·6H2O solid particles to the mixed solution and stir for 1.5 h to mix well;

[0051] 5) Add 20 mg of precipitant thiourea, stir at 80 ° C for 8 h, precipitate at room temperature for 24 h, filter, wash, dry at 60 ° C for 16 h, and calcine at 550 ° C in a tube furnace in an inert gas helium atmosphere for 7 h to obtain Fe2O3-La2O3-Rh2O3@HNi 0.4 S composite material.

[0052] The Fe2O3-La2O3-Rh2O3@HNi 0.4 The application of the S composite material in photocatalytic degradation of pyruvic acid in wastewater comprises the following steps:

[0053] A. Fe2O3-La2O3-Rh2O3@HNi 0.4 The S composite material was placed in a liquid film photoreactor, and the set temperature of the liquid film photoreactor was 20°C and the pressure was 0.3MPa;

[0054] B. Add wastewater to the liquid film photoreactor, the volume of wastewater does not exceed Fe2O3-La2O3-Rh2O3@HNi 0.4 S composite nickel mesh, argon was introduced into the liquid film photoreactor under dark conditions, the flow rate of argon was 50 mL / min, and the introduction time of argon was 50 min;

[0055] C. Under visible light irradiation, the light source is a 350W xenon lamp with a filter, and the concentration of pyruvate is measured after 2 hours of reaction.

[0056] Example 3

[0057] Fe2O3-La2O3-Rh2O3@HNi 0.6 The S composite material is composed of a nickel mesh and Fe2O3, La2O3, Rh2O3 and HNi attached to the nickel mesh. 0.6 S composition, Fe2O3, La2O3, Rh2O3 and HNi 0.6 The total amount of S loaded was 23% of the mass of the nickel mesh.

[0058] Fe2O3-La2O3-Rh2O3@HNi 0.6 The preparation method of the S composite material comprises the following steps:

[0059] 1) Soak in 0.1 mol / L dilute acetic acid for 2 h to remove the 4×4 cm 2 The oxide layer on the surface of the nickel mesh was then rinsed with deionized water three times and dried at 60 °C for 8 h;

[0060] 2) In a three-electrode battery system, Ni2O nanoparticles were grown on the surface of a nickel mesh by electrodeposition. 60 mg of NiSO4 and 50 mg of citric acid were added to 400 mL of deionized water. The pH value of the electrolyte was adjusted to 12 with 0.1 mol / L potassium hydroxide solution. A nickel mesh was used as the working electrode, a platinum plate was used as the counter electrode, and a silver electrode was used as the reference electrode. The deposition voltage was -0.7 V at a temperature of 70 °C. SAE The sample Ni2O-nm was obtained after deposition for 2 minutes. The particle size of Ni2O nanoparticles on the sample Ni2O-nm was 15 nm.

[0061] 3) Place the Ni2O-nm sample in a 0.08 mol / L sodium sulfide solution and stir at 30°C for 20 min to obtain a black sample Ni 0.6 S-nm;

[0062] 4) Ni 0.6 S-nm was placed in a 0.1 mol / mL dilute hydrochloric acid solution and etched at 90°C for 110 min to obtain a sample containing HNi 0.6 S-nm mixed solution, add 600 mg of Fe(NO3)3·9H2O, 300 mg of Rh(NO3)3·2H2O and 400 mg of La(NO3)3·6H2O solid particles to the mixed solution and stir for 2.5 h to mix well;

[0063] 5) Add 20 mg of urea as a precipitant, stir at 100 °C for 12 h, precipitate at room temperature for 12 h, filter, wash, dry at 100 °C for 8 h, and calcine at 700 °C in a tube furnace in an inert gas helium atmosphere for 3 h to obtain Fe2O3-La2O3-Rh2O3@HNi 0.6 S composite material.

[0064] The Fe2O3-La2O3-Rh2O3@HNi 0.6 The application of the S composite material in photocatalytic degradation of pyruvic acid in wastewater comprises the following steps:

[0065] A. Fe2O3-La2O3-Rh2O3@HNi 0.6 The S composite material was placed in a liquid film photoreactor, and the set temperature of the liquid film photoreactor was 30°C and the pressure was 0.2MPa;

[0066] B. Add wastewater to the liquid film photoreactor, the volume of wastewater does not exceed Fe2O3-La2O3-Rh2O3@HNi 0.6 S composite nickel mesh, argon was introduced into the liquid film photoreactor under dark conditions, the flow rate of argon was 100 mL / min, and the introduction time of argon was 30 min;

[0067] C. Under visible light irradiation, the light source is a 350W xenon lamp with a filter, and the concentration of pyruvate is measured after 4 hours of reaction.

[0068] Comparative Example 1

[0069] The difference between the preparation method of the composite material and that of Example 1 is that Rh(NO3)3·2H2O is not added in step 4) of this comparative example, and the remaining preparation methods and steps are the same as those of Example 1, and finally Fe2O3-La2O3@HNi 0.3 S composite material.

[0070] Fe2O3-La2O3@HNi 0.3 The application of the S composite material in photocatalytic degradation of pyruvic acid in wastewater comprises the following steps:

[0071] A. Fe2O3-La2O3@HNi 0.3 The S composite material was placed in a liquid film photoreactor, and the set temperature of the liquid film photoreactor was 25°C and the pressure was 0.1MPa;

[0072] B. Add wastewater to the liquid film photoreactor, the volume of wastewater does not exceed Fe2O3-La2O3@HNi 0.3 S composite nickel mesh, argon was introduced into the liquid film photoreactor under dark conditions, the flow rate of argon was 70 mL / min, and the introduction time of argon was 40 min;

[0073] C. Under visible light irradiation, the light source is a 350W xenon lamp with a filter, and the concentration of pyruvate is measured after 3 hours of reaction.

[0074] Comparative Example 2

[0075] The difference between the preparation method of the composite material and that of Example 1 is that La(NO3)3·6H2O is not added in step 4) of this comparative example, and the remaining preparation methods and steps are the same as those of Example 1, and finally Fe2O3-Rh2O3@HNi 0.3 S composite material.

[0076] Fe2O3-Rh2O3@HNi 0.3 The application of the S composite material in photocatalytic degradation of pyruvic acid in wastewater comprises the following steps:

[0077] A. Fe2O3-La2O3@HNi 0.3 The S composite material was placed in a liquid film photoreactor, and the set temperature of the liquid film photoreactor was 25°C and the pressure was 0.1MPa;

[0078] B. Add wastewater to the liquid film photoreactor, the volume of wastewater does not exceed Fe2O3-Rh2O3@HNi 0.3S composite nickel mesh, argon was introduced into the liquid film photoreactor under dark conditions, the flow rate of argon was 70 mL / min, and the introduction time of argon was 40 min;

[0079] C. Under visible light irradiation, the light source is a 350W xenon lamp with a filter, and the concentration of pyruvate is measured after 3 hours of reaction.

[0080] Comparative Example 3

[0081] In the preparation of the composite material, the difference from Example 1 is that step 2) is to grow Ni2O nanoparticles on the surface of the nickel mesh by electrodeposition in a three-electrode battery system, 30 mg of NiSO4 and 45 mg of citric acid are added to 200 mL of deionized water, the pH value of the electrolyte is adjusted to 11 with 25% ammonia water, the working electrode is a nickel mesh, the counter electrode is a platinum plate, and the reference electrode is a silver electrode; the temperature is 60°C and the deposition voltage is -0.6V SAE The sample Ni2O-nm was obtained after deposition for 10 min. The particle size of Ni2O nanoparticles on the sample Ni2O-nm was 65 nm.

[0082] The application of the composite material in photocatalytic degradation of pyruvic acid in wastewater comprises the following steps:

[0083] A. Fe2O3-La2O3-Rh2O3@HNi 0.3 The S composite material was placed in a liquid film photoreactor, and the set temperature of the liquid film photoreactor was 25°C and the pressure was 0.1MPa;

[0084] B. Add wastewater to the liquid film photoreactor, the volume of wastewater does not exceed Fe2O3-La2O3-Rh2O3@HNi 0.3 S composite nickel mesh, argon was introduced into the liquid film photoreactor under dark conditions, the flow rate of argon was 70 mL / min, and the introduction time of argon was 40 min;

[0085] C. Under visible light irradiation, the light source is a 350W xenon lamp with a filter, and the concentration of pyruvate is measured after 3 hours of reaction.

[0086] Comparative Example 4

[0087] Ni 0.3 The preparation method of S-nm material comprises the following steps:

[0088] 1) Soak in 0.1 mol / L dilute hydrochloric acid for 2 hours to remove the 4×4 cm 2 The oxide layer on the surface of the nickel mesh was then rinsed with deionized water three times and dried at 60 °C for 8 h;

[0089] 2) In a three-electrode battery system, Ni2O nanoparticles were grown on the surface of a nickel mesh by electrodeposition. 30 mg of NiSO4 and 45 mg of citric acid were added to 200 mL of deionized water. The pH value of the electrolyte was adjusted to 11 with 25% ammonia water. The working electrode was a nickel mesh, the counter electrode was a platinum plate, and the reference electrode was a silver electrode. The deposition voltage was -0.6 V at a temperature of 60 °C. SAE The sample Ni2O-nm was obtained after deposition for 8 min. The particle size of Ni2O nanoparticles on the sample Ni2O-nm was 30 nm.

[0090] 3) Place the Ni2O-nm sample in a 0.2 mol / L sodium sulfide solution and stir at 25°C for 30 min to obtain a black sample Ni 0.3 S-nm.

[0091] The evaluation results of the performance of the composite materials of the embodiment and the comparative example for photocatalyzing pyruvic acid in wastewater are shown in Table 1.

[0092] Degradation rate calculation formula:

[0093] ;

[0094] η is the degradation efficiency of pyruvate, C0 and C t are the initial concentration and concentration of pyruvate at time t respectively.

[0095] Table 1 Performance evaluation results of the composite materials of the examples and comparative examples for photocatalysis of pyruvic acid in wastewater

[0096]

[0097] As can be seen from Table 1, Rh(NO3)3·2H2O is not added in Comparative Example 1, and Rh2O3 is missing from the prepared composite material. As an efficient catalyst component, Rh2O3 has a unique electronic structure and catalytic active sites that play a vital role in promoting electron transfer and the stability of intermediate products in catalytic reactions. Therefore, when Rh2O3 is missing, the overall catalytic performance of the composite material will drop significantly. This drop is not only reflected in the slowing down of the reaction rate, but may also affect the selectivity and conversion rate of the product, because the presence of Rh2O3 can often optimize the reaction path and reduce the generation of by-products.

[0098] Comparative Example 2 does not add La(NO3)3·6H2O, resulting in the absence of La2O3 in the composite material. As a rare earth oxide, La2O3 has excellent ionic conductivity and electron modulation ability, and can effectively adjust the charge distribution and transport properties in the composite material. In addition, La2O3 can also form a stable solid solution or interface structure with Fe2O3 and Rh2O3, further enhancing the interaction and synergistic effect between the components. Therefore, the absence of La2O3 will destroy this synergistic effect, resulting in a significant decrease in catalytic performance.

[0099] Comparative Example 3 changes the particle size of Ni2O. Too large a particle size will reduce the specific surface area and the number of active sites, which will affect the recombination of photogenerated carriers and thus affect the catalytic performance. 0.3 The surface sulfur vacancies in nickel sulfide serve as catalytic sites, but their number and activity are often limited and are easily affected by environmental factors, which significantly reduces the catalytic efficiency.

[0100] Fe2O3-La2O3-Rh2O3@HNi prepared in Example 1 0.3 The cyclic performance test of the S composite material was carried out. The specific catalytic method was the same as that of Example 1. After one catalytic process, the activity of the composite material needed to be restored. Specifically, the composite material after the reaction was first washed with deionized water, dried for 12 hours, and then placed in a tube furnace for calcination for 8 hours at a heating temperature of 600°C. The degradation rate after 10 cycles is shown in Table 2. It can be seen from Table 2 that the Fe2O3-La2O3-Rh2O3@HNi prepared in Example 1 0.3 The S composite material still has good catalytic activity after 10 cycles.

[0101] Table 2 Cyclic performance test degradation rate

[0102]

Claims

1. Fe2O3-La2O3-Rh2O3@HNi x The method for preparing the S composite material is characterized in that: The following steps are involved: 1) Use dilute acid to remove the oxide layer on the surface of the nickel mesh, rinse the nickel mesh, and dry it; 2) Ni2O nanoparticles were grown on the surface of the nickel mesh by electrodeposition. The electrolyte was a mixture of NiSO4 and citric acid. The pH value of the electrolyte was adjusted to 10-12. The temperature was 50-70°C and the deposition voltage was -(0.5-0.7)V. SAE The sample Ni2O-nm is obtained by deposition for 2-6 minutes; the particle size of the Ni2O nanoparticles on the sample Ni2O-nm is one of 15nm, 20nm or 30nm; 3) Place the Ni2O-nm sample in a sodium sulfide solution and stir the reaction at 20-30°C for 20-40 minutes to obtain a black sample Ni x S-nm, where 0<x<1; 4) Ni x S-nm was placed in a dilute acid solution, where 0<x<1, and etched at 70-90℃ for 110-130min to obtain a sample containing HNi x A mixed solution of S-nm, wherein 0<x<1, is added with Fe(NO3)3·9H2O, Rh(NO3)3·2H2O and La(NO3)3·6H2O solid particles and stirred for 1.5-2.5h to mix evenly; 5) Add precipitant, stir at 80-100℃ for 8-12h, precipitate at room temperature for 12-24h, filter, wash, dry at 60-100℃ for 8-16h, and calcine in a tube furnace under an inert gas atmosphere to obtain Fe2O3-La2O3-Rh2O3@HNi x S composite material, where 0<x<1.

2. Fe2O3-La2O3-Rh2O3@HNi as claimed in claim 1 x The method for preparing the S composite material is characterized in that: In step 1), the acid is hydrochloric acid or acetic acid.

3. Fe2O3-La2O3-Rh2O3@HNi as claimed in claim 1 x The method for preparing the S composite material is characterized in that: In step 2), the working electrode is a nickel mesh, the counter electrode is a platinum plate, and the reference electrode is a silver electrode.

4. Fe2O3-La2O3-Rh2O3@HNi as claimed in claim 1 x The method for preparing the S composite material is characterized in that: In step 2), the pH is adjusted by using one of ammonia water, sodium hydroxide solution and potassium hydroxide solution with a mass concentration of 25%.

5. Fe2O3-La2O3-Rh2O3@HNi as claimed in claim 1 x The method for preparing the S composite material is characterized in that: In step 4), the dilute acid is dilute hydrochloric acid or dilute acetic acid.

6. Fe2O3-La2O3-Rh2O3@HNi as claimed in claim 1 x The method for preparing the S composite material is characterized in that: In step 5), the precipitant is thiourea or urea, the inert gas is argon or helium, the calcination temperature is 550-700° C., and the calcination time is 3-6 hours.

7. Fe2O3-La2O3-Rh2O3@HNi as claimed in claim 1 x The method for preparing the S composite material is characterized in that: The mass ratio of NiSO4 and citric acid in step 2) is (2-6):(3-5), and the concentration of the sodium sulfide solution in step 3) is 0.08-0.2 mol / L.

8. Fe2O3-La2O3-Rh2O3@HNi as claimed in claim 1 x The method for preparing the S composite material is characterized in that: In step 4), the mass ratio of Fe(NO3)3·9H2O, Rh(NO3)3·2H2O and La(NO3)3·6H2O is (4-6):(3-4):(3-4); the ratio of the sum of the masses of Fe(NO3)3·9H2O, Rh(NO3)3·2H2O and La(NO3)3·6H2O to the mass of the precipitant is (55-65):

1.

9. Fe2O3-La2O3-Rh2O3@HNi prepared by the preparation method according to any one of claims 1 to 8 x S composite material.

10. Fe2O3-La2O3-Rh2O3@HNi as claimed in claim 9 x The application of S composite material in photocatalytic degradation of pyruvic acid in wastewater is characterized in that: The following steps are involved: A. Fe2O3-La2O3-Rh2O3@HNi x The S composite material is placed in a liquid film photoreactor, wherein 0<x<1, the set temperature of the liquid film photoreactor is 20-30°C, and the pressure is 0.1-0.3MPa; B. Add wastewater to the liquid film photoreactor, the volume of wastewater does not exceed Fe2O3-La2O3-Rh2O3@HNi x S composite nickel mesh, wherein 0<x<1, argon is introduced into the liquid film photoreactor under dark conditions, the flow rate of argon is 50-100mL / min, and the introduction time of argon is 30-50min; C. Measure the concentration of pyruvate under visible light after 2-4 hours of reaction.

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