Garbage leachate electrocatalytic plate and preparation method and application thereof

Abstract

The invention discloses a landfill leachate electrocatalytic plate in the field of electrocatalytic technology, a preparation method and an application thereof. After the surface of a titanium substrate is activated, ruthenium, iridium, copper and cobalt metal elements are introduced, and thioacetamide and 2-methylimidazole are used to form sulfur and nitrogen doping, and finally a multi-element heterojunction structure is formed on the titanium substrate. The catalytic activity of the electrocatalytic plate can be improved, the electrocatalytic plate has high pH stability and corrosion resistance, can adapt to long-term operation, and has strong recyclability and sustainability.

Description

Technical Field

[0001] The invention belongs to the technical field of electrocatalysis, and specifically refers to a landfill leachate electrocatalytic plate and a preparation method and application thereof. Background Art

[0002] Leachate is the liquid that penetrates into the garbage layer and dissolves or carries pollutants after the garbage in the landfill comes into contact with water bodies such as precipitation and groundwater. As time goes by, the leachate will continue to accumulate, and its pollution components are very complex, containing a large number of toxic and harmful substances, such as organic pollutants, ammonia nitrogen, heavy metals, pathogenic microorganisms, etc. The pollutant content of the leachate varies with factors such as the composition of the garbage, precipitation, and landfill time. Therefore, the treatment of leachate has become a key environmental protection issue in landfill management. The characteristics of landfill leachate include: organic pollutants: including organic matter with high dissolved organic carbon (DOC) and chemical oxygen demand (COD), which can easily cause eutrophication of water bodies; ammonia nitrogen: garbage contains a large amount of organic nitrogen, and the concentration of ammonia nitrogen in leachate is often high. If it is not treated and discharged, it will have a serious impact on water quality and water ecology; heavy metals: heavy metals such as lead, cadmium, and mercury will be released into the leachate with the degradation of garbage, which is highly toxic; acidic or alkaline: due to the decomposition of substances in the garbage, the pH value of the leachate may be acidic or alkaline, which also increases the difficulty of treatment; if the landfill leachate is not treated in a timely and effective manner, it may have a long-term negative impact on groundwater, surface water and the surrounding environment, so effective technology needs to be adopted for treatment. The treatment methods of landfill leachate can be divided into several types, such as physical, chemical and biological methods, which are usually selected and combined according to the characteristics of the leachate, treatment requirements and economic feasibility. Common treatment methods include the following: Membrane separation technology: including ultrafiltration, nanofiltration and reverse osmosis, which can effectively remove most of the dissolved organic matter, heavy metals and inorganic salts in the leachate. In particular, reverse osmosis membrane separation can remove most of the dissolved pollutants, but the pollution and cleaning cycle of the membrane are its main problems; Adsorption method: using activated carbon or other adsorption materials to adsorb harmful substances in the leachate, especially organic matter and certain heavy metal ions. Activated carbon has strong adsorption capacity, but needs to be replaced or regenerated regularly; Chlorination / Ozone Oxidation: Using chlorine or ozone for oxidation reaction can remove organic pollutants and pathogenic microorganisms in leachate, and can also reduce COD value; Chemical precipitation method: Using chemical agents (such as lime, aluminum sulfate, etc.) to precipitate soluble metal ions in leachate, especially suitable for the removal of heavy metals; Anaerobic biological treatment method: Degradation of organic matter and ammonia nitrogen in leachate by anaerobic microorganisms, especially suitable for high-concentration organic wastewater, can effectively reduce COD and ammonia nitrogen concentration; Electrocatalysis: Promote the degradation or oxidation of organic matter and ammonia nitrogen on the electrode surface through electrocatalytic reaction, with good efficiency and prospects. Although some electrocatalytic materials such as titanium-based electrodes and carbon-based materials have good corrosion resistance, long-term use may still lead to reduced catalytic activity on the electrode surface, or even corrosion or oxidation, affecting the treatment efficiency; If precious metals (such as platinum, ruthenium, etc.) are used as catalysts, although their catalytic activity is high, they are expensive, and may face long-term wear and performance degradation in actual operation. Summary of the invention

[0003] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a landfill leachate electrocatalytic plate and a preparation method and application thereof. After the surface of the titanium substrate is activated, ruthenium, iridium, copper, and cobalt metal elements are introduced, and thioacetamide and 2-methylimidazole are used to form sulfur and nitrogen doping, and finally a multi-heterojunction structure is formed on the titanium substrate, which can improve the catalytic activity of the electrocatalytic plate, has high pH stability and corrosion resistance, can adapt to long-term operation, and has strong recyclability and sustainability.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] The present invention also provides a method for preparing a landfill leachate electrocatalytic plate, which specifically comprises the following steps:

[0006] S1. Sandblasting the surface of the titanium substrate, wherein the diameter of the sand particles used for sandblasting is 0.5-1 mm;

[0007] S2, immersing the titanium substrate after sandblasting in step S1 in an alkaline washing solution, raising the temperature to 70-80°C, and performing alkaline washing for 1.5-2.5 hours, and then repeatedly washing with deionized water and acetone three times in sequence, placing it in deionized water, and performing ultrasonic treatment at 500-600W for 10-20min to obtain a pretreated titanium substrate;

[0008] Preferably, in step S2, the alkaline washing solution comprises the following components: 40-50 g / L sodium carbonate, 5-10 g / L sodium hydroxide, 60-80 g / L sodium phosphate, 1-1.5 g / L sodium dodecyl sulfate, and 1-2 g / L hydrogen peroxide;

[0009] S3, after heating the oxalic acid solution to boiling, placing the pretreated titanium substrate prepared in step S2 in the oxalic acid solution, performing pickling treatment at 80-90° C. for 2-3 hours, washing repeatedly with deionized water and acetone in sequence, placing in deionized water, ultrasonically treating at 500-600 W for 20-30 minutes, vacuum drying, and immersing in anhydrous ethanol to obtain an activated titanium substrate;

[0010] Preferably, in step S3, the mass concentration of oxalic acid in deionized water in the oxalic acid solution is 80-100 g / L;

[0011] S4, dispersing copper nitrate in methanol aqueous solution, placing it under 400-500W for ultrasonic treatment, after the reaction solution turns blue, adding 2-hydroxy-p-dibenzoic acid, stirring at 150-180rpm for reaction at room temperature for 2-3h, standing for 12-16h, centrifuging at 5000rpm for 5min, collecting the precipitate, washing it with deionized water and anhydrous ethanol, and vacuum drying to obtain Cu-MOF;

[0012] Preferably, in step S4, the mass concentration of copper nitrate in the methanol aqueous solution is 15-20 g / L;

[0013] Preferably, in step S4, the mass concentration of the 2-hydroxybenzoic acid in the methanol aqueous solution is 8-10 g / L;

[0014] S5, dispersing the Cu-MOF prepared in step S4 in deionized water, stirring at 600-800 rpm, and obtaining a Cu-MOF dispersion after being uniformly suspended, adding a ruthenium chloride solution and an iridium chloride solution, stirring at 800-1000 rpm, reacting for 18-24 hours, filtering and collecting the precipitate, repeatedly washing with deionized water and acetone, and freeze-drying to obtain RuIrCu-MOF;

[0015] Preferably, in step S5, the mass concentration of the Cu-MOF in deionized water is 0.2%-0.4%;

[0016] Preferably, in step S5, the mass concentration of ruthenium trichloride in deionized water in the ruthenium trichloride solution is 5-10 g / L;

[0017] Preferably, in step S5, the mass concentration of iridium chloride in deionized water in the iridium chloride solution is 10-15 g / L;

[0018] Preferably, in step S5, the added volume of the ruthenium chloride solution is 7%-10% of the volume of the Cu-MOF dispersion;

[0019] Preferably, in step S5, the added volume of the iridium chloride solution is 5%-7% of the volume of the Cu-MOF dispersion;

[0020] S6, dispersing the RuIrCu-MOF prepared in step S5 in DMF solvent, adding thioacetamide, mixing evenly, immersing the activated titanium substrate prepared in step S3 in the reaction system, transferring to a high-pressure reactor, adjusting the temperature to 220-250° C., reacting for 20-28 hours, cooling, washing with anhydrous ethanol and deionized water, and vacuum drying to obtain a modified titanium substrate;

[0021] Preferably, in step S6, the mass concentration of the RuIrCu-MOF in the DMF solvent is 1-1.5 g / L;

[0022] Preferably, in step S6, the mass ratio between the RuIrCu-MOF and thioacetamide is 0.6-0.8:1;

[0023] S7, prepare 2-methylimidazole and cobalt nitrate hexahydrate solution respectively, mix the two to form a uniform reaction system, immerse the modified titanium substrate prepared in step S6 in the reaction system, place it in an oscillator at a speed of 120 rpm for 1.5-2.5 hours, take out the modified titanium substrate, wash it with deionized water and anhydrous ethanol, place it in a high-pressure reactor, and in an argon atmosphere, increase the temperature to 600-700° C. at 10° C. / min, and keep it warm for 2-3 hours to obtain an electrocatalytic plate;

[0024] Preferably, in step S7, in the 2-methylimidazole solution, the mass concentration of 2-methylimidazole in methanol is 40-50 g / L;

[0025] Preferably, in step S7, in the cobalt nitrate hexahydrate solution, the mass concentration of cobalt nitrate hexahydrate in methanol is 50-60 g / L;

[0026] Preferably, in step S7, the mass ratio between the 2-methylimidazole and the cobalt nitrate hexahydrate is 0.8-1:1-1.2.

[0027] The present invention also provides a landfill leachate electrocatalytic plate prepared according to the method.

[0028] The present invention also provides an application of an electrocatalytic plate in an electrocatalytic oxidation treatment device for landfill leachate, wherein the electrocatalytic oxidation treatment device comprises an electrode group, an adaptable power supply, and a reaction tank;

[0029] Preferably, the electrocatalytic plate is used as an anode plate of a device for electrocatalytic oxidation treatment of landfill leachate;

[0030] Preferably, the cathode plate material includes at least one of a carbon plate, a 316 stainless steel plate and a pure titanium plate;

[0031] Preferably, the spacing between the electrocatalytic plate and the cathode plate in the electrode group is 1-4 cm; the surface area of ​​the electrocatalytic plate and the cathode plate is 0.1-0.08 m 2 .

[0032] The beneficial effects achieved by the present invention are as follows:

[0033] The invention provides a landfill leachate electrocatalytic plate and a preparation method and application thereof. After the surface of a titanium substrate is activated, ruthenium, iridium, copper and cobalt metal elements are introduced, and thioacetamide and 2-methylimidazole are used to form sulfur and nitrogen doping, and finally a multi-element heterojunction structure is formed on the titanium substrate, which can improve the catalytic activity of the electrocatalytic plate, has high pH stability and corrosion resistance, can adapt to long-term operation, and has strong recyclability and sustainability. In the invention, ruthenium and iridium are noble metal catalysts, and a Cu-MOF precursor is formed by a Cu salt solution and 2-hydroxy-p-dibenzoic acid, and the precursor is immersed in a ruthenium salt and iridium salt solution to undergo a replacement reaction to generate a RuIrCu-MOF structure. The modified titanium substrate is subjected to a sulfurization reaction with thioacetamide to form a sulfur-doped metal MOF structure on the surface of the titanium substrate, and a sulfur-doped multi-metal heterojunction structure is formed after sintering, thereby increasing the reaction active sites of electrocatalytic oxidation; in the present invention, a composite is formed by using 2-methylimidazole and a cobalt salt to form a carbon-nitrogen modified multi-metal doped heterojunction structure after sintering, thereby providing additional catalytic reaction active sites, and the charge offset formed in the heterojunction can promote the separation of electron holes and improve the catalytic efficiency, and the doping of sulfur and nitrogen in the multi-metal heterojunction structure can reduce the dissolution, oxidation and structural collapse of the electrocatalytic surface, thereby improving the corrosion resistance and pollution resistance of the electrocatalytic plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the structure of the electrocatalytic oxidation treatment device prepared in Example 1 of the present invention;

[0035] Figure 2 This is a SEM image of the electrocatalytic plate prepared in Example 1 of the present invention;

[0036] Figure 3 The results of enhanced electrolysis life of the electrocatalytic plates prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 are shown;

[0037] Figure 4 This is a graph showing the COD removal rate results of the electrocatalytic oxidation treatment device assembled with the electrocatalytic plates prepared in Examples 1-3 of the present invention and Comparative Examples 1-3.

[0038] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0041] The experimental methods in the following examples are conventional methods unless otherwise specified; the experimental materials and test strains used in the following examples are purchased from commercial channels unless otherwise specified.

[0042] Example 1

[0043] This embodiment provides a method for preparing a landfill leachate electrode plate, which specifically includes the following steps:

[0044] S1, washing the surface of the titanium substrate with acetone, drying it, and then sandblasting it with aluminum oxide sand with a particle size of 0.5 mm, setting the nozzle diameter of the sandblasting machine to 5 mm, and sandblasting at a spray angle of 45°. After sandblasting, use high pressure to blow off the residual sand on the surface of the titanium substrate for standby use;

[0045] S2, prepare 1L of alkaline washing solution according to 40g / L of sodium carbonate, 7g / L of sodium hydroxide, 80g / L of sodium phosphate, 1.5g / L of sodium dodecyl sulfate and 2g / L of hydrogen peroxide, immerse the titanium substrate after sandblasting in step S1 in the alkaline washing solution, increase the temperature to 80°C, perform alkaline washing for 2h, remove the titanium substrate, wash it repeatedly with deionized water and acetone three times in sequence, place it in deionized water in an ultrasonic cleaning machine and perform ultrasonic treatment for 10min at 600W to obtain a pretreated titanium substrate;

[0046] S3, prepare 1L of 80g / L oxalic acid solution, heat the oxalic acid solution to boiling, transfer the pretreated titanium substrate prepared in step S2 to the oxalic acid solution, maintain the temperature at 90°C, and perform pickling treatment. After 2 hours, take out the titanium substrate, wash it repeatedly with deionized water and acetone three times in sequence, place it in deionized water and perform ultrasonic treatment in an ultrasonic cleaning machine at 600W for 20 minutes, place it in a vacuum drying oven at 40°C for drying treatment, and after treatment, soak it in anhydrous ethanol to obtain an activated titanium substrate for standby use;

[0047] S4. Accurately weigh 1.5 g of copper nitrate, place it in 100 mL of 70 vol% methanol aqueous solution, and place it under 400 W for ultrasonic treatment. After the copper nitrate is completely dissolved and the reaction system turns blue, accurately weigh 1.0 g of 2-hydroxyterephthalic acid, add it to the reaction system for mixing, and stir at room temperature at a speed of 180 rpm. After reacting for 2 hours, let the reaction system stand for 12 hours, centrifuge at 500 rpm for 5 minutes, collect the precipitate, resuspend and wash it with deionized water and anhydrous ethanol in turn, collect the washed precipitate, and place it in a vacuum drying oven at 40°C for 4 hours to obtain Cu-MOF;

[0048] S5. Accurately weigh 2 g of the Cu-MOF prepared in step S4 and place it in 1 L of deionized water. Stir it at 800 rpm until it becomes uniform to obtain a Cu-MOF dispersion. Prepare 100 mL of a ruthenium chloride solution at a mass concentration of 10 g / L and 100 mL of an iridium chloride solution at a mass concentration of 10 g / L. Add 100 mL of the ruthenium chloride solution and 70 mL of the iridium chloride solution to the Cu-MOF dispersion. Adjust the stirring speed to 1000 rpm. After stirring for 24 hours, filter and collect the precipitate. Wash it three times with deionized water and acetone, and freeze-dry it to obtain RuIrCu-MOF.

[0049] S6. Accurately weigh 100 mg of RuIrCu-MOF and place it in 100 mL of DMF solvent. After mixing evenly, add 125 mg of thioacetamide and mix evenly. Then, immerse the activated titanium substrate prepared in step S3 in the reaction system, transfer it to a high-pressure reactor, adjust the temperature to 220° C., and keep the reaction for 24 hours. After the reaction system is cooled to room temperature, it is repeatedly washed three times with anhydrous ethanol and deionized water, and then vacuum dried to obtain a modified titanium substrate.

[0050] S7. Accurately weigh 0.8 g of 2-methylimidazole and dissolve it in 20 mL of methanol to prepare a 2-methylimidazole solution. Accurately weigh 1.2 g of cobalt nitrate hexahydrate and dissolve it in 20 mL of methanol to prepare a cobalt nitrate hexahydrate solution. After the 2-methylimidazole solution and the cobalt nitrate hexahydrate solution are mixed, the modified titanium substrate prepared in step S6 is immersed in the reaction system, placed in an oscillator and oscillated at 120 rpm for 2 hours, the modified titanium substrate is taken out, and washed repeatedly three times with deionized water and anhydrous ethanol in sequence, and then placed in a high-pressure reactor, argon gas is introduced, and the temperature is increased to 600° C. at 10° C. / min in a flowing argon atmosphere, and the electrocatalytic plate is obtained after sintering at this temperature for 3 hours.

[0051] This embodiment also provides a landfill leachate electrocatalytic plate prepared according to the above preparation method.

[0052] This embodiment also provides an application of the electrocatalytic plate as described above in a device for electrocatalytic oxidation treatment of landfill leachate, wherein the device comprises an electrode group, an adaptor power supply and a reaction tank; the electrode group comprises an electrocatalytic electrode plate and an anode plate; the anode plate is made of pure titanium plate;

[0053] Figure 1 The schematic diagram of the electrocatalytic oxidation treatment device prepared in Example 1 of the present invention is as follows: Figure 1 As shown, the electrocatalytic oxidation treatment device comprises a reaction tank 1, the bottom of which is fixedly connected to an electrocatalytic plate 3 and a cathode plate 4, and the plate surface area of ​​the electrocatalytic plate 3 and the anode plate 4 is 0.1 m 2 The electrocatalytic plate 3 and the cathode plate 4 are spaced 4 cm apart and arranged in parallel. The electrocatalytic plate 3 and the anode plate 4 are connected to the adaptable power supply 2 through wires.

[0054] Example 2

[0055] This embodiment provides a method for preparing a landfill leachate electrode plate, which specifically includes the following steps:

[0056] S1, washing the surface of the titanium substrate with acetone, drying it, and then sandblasting it with aluminum oxide sand with a particle size of 1 mm, setting the nozzle diameter of the sandblasting machine to 5 mm, and sandblasting at a spray angle of 45°. After sandblasting, use high pressure to blow off the residual sand on the surface of the titanium substrate for standby use;

[0057] S2, prepare 1L of alkaline washing solution according to 45g / L of sodium carbonate, 5g / L of sodium hydroxide, 70g / L of sodium phosphate, 1g / L of sodium dodecyl sulfate, and 1.5g / L of hydrogen peroxide, immerse the titanium substrate after sandblasting in step S1 in the alkaline washing solution, increase the temperature to 80°C, perform alkaline washing for 2h, remove the titanium substrate, wash it repeatedly with deionized water and acetone three times in sequence, place it in deionized water in an ultrasonic cleaning machine and perform ultrasonic treatment for 10min at 600W to obtain a pretreated titanium substrate;

[0058] S3, prepare 1L of 90g / L oxalic acid solution, heat the oxalic acid solution to boiling, transfer the pretreated titanium substrate prepared in step S2 to the oxalic acid solution, maintain the temperature at 80°C, and perform pickling treatment. After 3 hours, take out the titanium substrate, wash it repeatedly with deionized water and acetone three times in sequence, place it in deionized water and perform ultrasonic treatment in an ultrasonic cleaning machine at 500W for 25 minutes, place it in a vacuum drying oven at 40°C for drying treatment, and after treatment, soak it in anhydrous ethanol to obtain an activated titanium substrate for standby use;

[0059] S4. Accurately weigh 2.0 g of copper nitrate, place it in 100 mL of 70 vol% methanol aqueous solution, and place it under 500 W for ultrasonic treatment. After the copper nitrate is completely dissolved and the reaction system turns blue, accurately weigh 0.9 g of 2-hydroxyterephthalic acid, add it to the reaction system for mixing, and stir at room temperature at a speed of 180 rpm. After reacting for 3 hours, let the reaction system stand for 16 hours, centrifuge at 500 rpm for 5 minutes, collect the precipitate, resuspend and wash it with deionized water and anhydrous ethanol in turn, collect the washed precipitate, and place it in a vacuum drying oven at 40°C for 4 hours to obtain Cu-MOF;

[0060] S5. Accurately weigh 4 g of the Cu-MOF prepared in step S4 and place it in 1 L of deionized water. Stir it at 600 rpm until it becomes uniform to obtain a Cu-MOF dispersion. Prepare 100 mL of a ruthenium chloride solution at a mass concentration of 5 g / L and 100 mL of an iridium chloride solution at a mass concentration of 15 g / L. Take 70 mL of the ruthenium chloride solution and 60 mL of the iridium chloride solution and add them to the Cu-MOF dispersion. Adjust the stirring speed to 800 rpm. After stirring for 20 hours, filter and collect the precipitate, wash it repeatedly with deionized water and acetone three times, and freeze-dry it to obtain RuIrCu-MOF.

[0061] S6. Accurately weigh 120 mg of RuIrCu-MOF and place it in 100 mL of DMF solvent. After mixing evenly, add 200 mg of thioacetamide and mix evenly. Then, immerse the activated titanium substrate prepared in step S3 in the reaction system, transfer it to a high-pressure reactor, adjust the temperature to 230° C., and keep the reaction for 28 hours. After the reaction system is cooled to room temperature, it is repeatedly washed three times with anhydrous ethanol and deionized water, and then vacuum dried to obtain a modified titanium substrate.

[0062] S7. Accurately weigh 0.9 g of 2-methylimidazole and dissolve it in 20 mL of methanol to prepare a 2-methylimidazole solution. Accurately weigh 1.1 g of cobalt nitrate hexahydrate and dissolve it in 20 mL of methanol to prepare a cobalt nitrate hexahydrate solution. After the 2-methylimidazole solution and the cobalt nitrate hexahydrate solution are mixed, the modified titanium substrate prepared in step S6 is immersed in the reaction system, placed in an oscillator and oscillated at 120 rpm for 1.5 hours, the modified titanium substrate is taken out, and washed repeatedly three times with deionized water and anhydrous ethanol in sequence, and then placed in a high-pressure reactor, argon gas is introduced, and the temperature is increased to 700° C. at 10° C. / min in a flowing argon atmosphere, and sintered for 2 hours to obtain an electrocatalytic plate.

[0063] This embodiment also provides a landfill leachate electrocatalytic plate prepared according to the above preparation method.

[0064] This embodiment also provides an application of the electrocatalytic plate as described above in a device for electrocatalytic oxidation treatment of landfill leachate, wherein the device comprises a plate group, an adaptor power supply and a reaction tank; the plate group comprises an electrocatalytic plate and an anode plate; the anode plate is made of pure titanium; the plate surface area of ​​the electrocatalytic plate 3 and the anode plate 4 is 0.08 m 2 The plate surfaces of the electrocatalytic plate 3 and the cathode plate 4 are spaced 1 cm apart.

[0065] Example 3

[0066] This embodiment provides a method for preparing a landfill leachate electrode plate, which specifically includes the following steps:

[0067] S1, washing the surface of the titanium substrate with acetone, drying it, and then sandblasting it with aluminum oxide sand with a particle size of 0.8 mm, setting the nozzle diameter of the sandblasting machine to 5 mm, and sandblasting at a spray angle of 45°. After sandblasting, use high pressure to blow off the residual sand on the surface of the titanium substrate for standby use;

[0068] S2, prepare 1L of alkaline washing solution according to 50g / L of sodium carbonate, 10g / L of sodium hydroxide, 60g / L of sodium phosphate, 1.2g / L of sodium dodecyl sulfate, and 1g / L of hydrogen peroxide, immerse the titanium substrate after sandblasting in step S1 in the alkaline washing solution, increase the temperature to 80°C, perform alkaline washing for 2h, remove the titanium substrate, wash it repeatedly with deionized water and acetone three times in sequence, place it in deionized water in an ultrasonic cleaning machine and perform ultrasonic treatment for 10min at 600W to obtain a pretreated titanium substrate;

[0069] S3, prepare 1L of 100g / L oxalic acid solution, heat the oxalic acid solution to boiling, transfer the pretreated titanium substrate prepared in step S2 to the oxalic acid solution, maintain the temperature at 85°C, and perform pickling treatment. After 2 hours, take out the titanium substrate, wash it repeatedly with deionized water and acetone three times in sequence, place it in deionized water and perform ultrasonic treatment at 550W for 30 minutes in an ultrasonic cleaning machine, place it in a vacuum drying oven at 40°C for drying treatment, and after treatment, soak it in anhydrous ethanol to obtain an activated titanium substrate for standby use;

[0070] S4. Accurately weigh 1.8 g of copper nitrate, place it in 100 mL of 70 vol% methanol aqueous solution, and place it under 450 W for ultrasonic treatment. After the copper nitrate is completely dissolved and the reaction system turns blue, accurately weigh 0.8 g of 2-hydroxyterephthalic acid, add it to the reaction system for mixing, and stir at room temperature at a speed of 180 rpm. After reacting for 2.5 hours, let the reaction system stand for 14 hours, centrifuge at 500 rpm for 5 minutes, collect the precipitate, resuspend and wash it with deionized water and anhydrous ethanol in turn, collect the washed precipitate, and place it in a vacuum drying oven at 40°C for 4 hours to obtain Cu-MOF;

[0071] S5. Accurately weigh 3 g of the Cu-MOF prepared in step S4 and place it in 1 L of deionized water. Stir it at 700 rpm until it becomes uniform to obtain a Cu-MOF dispersion. Prepare 100 mL of ruthenium chloride solution at a mass concentration of 8 g / L and 100 mL of iridium chloride solution at a mass concentration of 12 g / L. Take 80 mL of the ruthenium chloride solution and 50 mL of the iridium chloride solution and add them to the Cu-MOF dispersion. Adjust the stirring speed to 900 rpm. After stirring for 18 hours, filter and collect the precipitate, wash it repeatedly with deionized water and acetone three times, and freeze-dry it to obtain RuIrCu-MOF.

[0072] S6. Accurately weigh 150 mg of RuIrCu-MOF and place it in 100 mL of DMF solvent. After mixing evenly, add 200 mg of thioacetamide and mix evenly. Then, immerse the activated titanium substrate prepared in step S3 in the reaction system, transfer it to a high-pressure reactor, adjust the temperature to 250° C., and keep the reaction for 20 hours. After the reaction system is cooled to room temperature, it is repeatedly washed three times with anhydrous ethanol and deionized water, and then vacuum dried to obtain a modified titanium substrate.

[0073] S7. Accurately weigh 1.0 g of 2-methylimidazole and dissolve it in 20 mL of methanol to prepare a 2-methylimidazole solution. Accurately weigh 1.0 g of cobalt nitrate hexahydrate and dissolve it in 20 mL of methanol to prepare a cobalt nitrate hexahydrate solution. After the 2-methylimidazole solution and the cobalt nitrate hexahydrate solution are mixed, the modified titanium substrate prepared in step S6 is immersed in the reaction system, placed in an oscillator and oscillated at 120 rpm for 2.5 hours, the modified titanium substrate is taken out, and washed repeatedly three times with deionized water and anhydrous ethanol in sequence, and then placed in a high-pressure reactor, argon gas is introduced, and the temperature is increased to 650° C. at 10° C. / min in a flowing argon atmosphere. After sintering for 3 hours, an electrocatalytic plate is obtained.

[0074] This embodiment also provides a landfill leachate electrocatalytic plate prepared according to the above preparation method.

[0075] This embodiment also provides an application of the electrocatalytic plate as described above in a device for electrocatalytic oxidation treatment of landfill leachate, wherein the device comprises a plate group, an adaptor power supply and a reaction tank; the plate group comprises an electrocatalytic plate and an anode plate; the anode plate is made of pure titanium; the plate surface area of ​​the electrocatalytic plate 3 and the anode plate 4 is 0.1 m 2 The plate surfaces of the electrocatalytic plate 3 and the cathode plate 4 are spaced 2 cm apart.

[0076] Comparative Example 1

[0077] This comparative example provides an electrocatalytic plate and a preparation method thereof, which is different from Example 1 only in that the preparation method does not include step S7, and the remaining components and component contents are the same as those in Example 1.

[0078] Comparative Example 2

[0079] This comparative example provides an electrocatalytic plate and a preparation method thereof, which is different from Example 1 only in that the preparation method does not include step S6, and the remaining components and component contents are the same as those in Example 1.

[0080] Comparative Example 3

[0081] The present comparative example provides an electrocatalytic plate and a preparation method thereof, which differs from Example 1 only in that the preparation method does not include steps S4 and S5, and the preparation method of the modified titanium substrate described in step S6 is implemented according to the following steps: preparing a ruthenium chloride solution and a 10 g / L iridium chloride solution with a mass concentration of 10 g / L, mixing them evenly to obtain a mixed precursor solution, applying the mixed precursor solution on the activated titanium substrate prepared in step S3, first drying it in an oven at 120°C for 10 min, then transferring it to a muffle furnace at 450°C and calcining it for 15 min, taking out the titanium substrate after cooling, repeating the steps of applying the mixed precursor solution, drying, and calcining, applying 10 layers of the mixed precursor solution, and finally calcining them in a muffle furnace for 1 h to obtain an electrocatalytic plate, and the remaining components and component contents are the same as those in Example 1.

[0082] Experimental Example 1

[0083] The microscopic morphology of the electrocatalytic plate prepared in Example 1 was observed using a scanning electron microscope. Figure 2The SEM image of the electrocatalytic plate prepared in Example 1 of the present invention shows that there is an irregular flaky structure on the surface of the titanium substrate, and there is a certain layered structure superimposed. After the titanium substrate is activated, the surface of the titanium substrate has abundant active groups. The organic ligand of Cu-MOF is 2-hydroxyterephthalic acid. The carboxyl group can form a coordination effect with copper ions to form a MOF structure. The hydroxyl group can increase the fixation of the MOF structure on the titanium substrate. After the copper ions are replaced by ruthenium ions and iridium ions, sulfur is introduced, and the cobalt source solution forms a complex with 2-methylimidazole, which can be fixed on the modified titanium substrate. At the same time, a complex with a three-dimensional structure is formed on the surface of the titanium substrate. After high-temperature sintering, cobalt sulfide is formed, so that the surface of the titanium substrate has an irregular flaky heterojunction structure, which increases the catalytic active reaction sites and can improve the catalytic activity of the titanium substrate.

[0084] Experimental Example 2

[0085] In this experimental example, Shanghai Chenhua CHI700E electrochemical workstation was used to conduct enhanced electrolysis life test on the electrocatalytic plates prepared in Examples 1-3 and Comparative Examples 1-3, the current density was set to 5000A / m2, the electrolyte was 3.5wt% sodium chloride solution, and the cell pressure change was recorded;

[0086] Figure 3 The results of the electrocatalytic plate enhanced electrolysis life prepared by Examples 1-3 of the present invention and Comparative Examples 1-3 are shown in the figure; the active ingredients of the electrocatalytic plate are continuously reduced during the stabilization process, resulting in a slow increase in voltage. As the concentration of active oxygen ions increases, a passivation film is formed on the surface of the electrocatalytic plate or corrosion occurs, resulting in a rapid increase in voltage in a short period of time, leading to failure of the electrocatalytic plate. The electrocatalytic plates prepared by Examples 1-3 have a longer stable state, which can be maintained for 270-280 hours, while the stable state of Comparative Example 1 can be maintained for about 200 hours, followed by Comparative Example 2, which can maintain a stable state for 168 hours. The plate most susceptible to active oxygen passivation and corrosion is the electrocatalytic plate prepared by Comparative Example 3, and its stable state can only be maintained for 140-144 hours.

[0087] Experimental Example 3

[0088] In this experimental example, the electrocatalytic plates prepared in Examples 1-3 and Comparative Examples 1-3 are used to form an electrocatalytic oxidation treatment device to oxidize and decompose harmful substances in landfill leachate. The landfill leachate is taken from a waste incineration station in Jiangsu Province. The leachate is collected and stored at room temperature. After biochemical treatment, the components in the landfill leachate are shown in the following table:

[0089] Ingredients (g / L) <![CDATA[Cl - ]]> <![CDATA[Na + ]]> <![CDATA[K + ]]> <![CDATA[Ca 2+ ]]> <![CDATA[SO 4 2- ]]> <![CDATA[NO 3 - ]]> TOC COD content 3.38 3.12 2.89 0.45 0.34 1.67 0.41 0.98

[0090] The landfill leachate was placed in a reaction tank and stirred at 500 rpm. After the power was turned on at 35°C, the voltage was adjusted to 22 V. 2 mL of samples were taken at regular intervals, and centrifuged at 5000 rpm for 10 min. 1 mL of the supernatant was taken and filtered. The COD content in the sample was analyzed by GC-MS.

[0091] Figure 4 The electrocatalytic oxidation treatment device assembled with the electrocatalytic plates prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 is a resultant graph of the removal rate of COD; as shown in the figure, the electrocatalytic oxidation treatment device described in Examples 1-3 can quickly degrade COD, and can decompose the COD content from 983 mg / L to 5.8-7.1 mg / L within 3h-4h; the electrocatalytic plate prepared in Comparative Example 1 has a slow decomposition rate for COD, and the surface of the electrocatalytic plate lacks a heterojunction structure composed of Co, resulting in a reduction in the catalytic active sites of the reaction; and the electrocatalytic plate prepared in Comparative Example 2 lacks S doping, resulting in a corrosion layer or a passivation layer formed on the surface of the electrocatalytic plate, resulting in the degradation of COD being affected; the surface of the electrocatalytic plate prepared in Comparative Example 3 has a faster degradation rate in the initial stage of the COD degradation reaction due to the retention of metal sites, but the COD degradation reaction is hindered due to the passivation and corrosion of the catalytic active sites.

[0092] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

[0093] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a landfill leachate electrocatalytic plate, characterized in that: The specific steps include: S1. Sandblasting the surface of the titanium substrate, wherein the diameter of the sand particles used for sandblasting is 0.5-1 mm; S2, immersing the titanium substrate after sandblasting in step S1 in an alkaline washing solution, raising the temperature to 70-80°C, and performing alkaline washing for 1.5-2.5 hours, and then repeatedly washing with deionized water and acetone three times in sequence, placing it in deionized water, and performing ultrasonic treatment at 500-600W for 10-20min to obtain a pretreated titanium substrate; S3, after heating the oxalic acid solution to boiling, placing the pretreated titanium substrate prepared in step S2 in the oxalic acid solution, performing pickling treatment at 80-90° C. for 2-3 hours, washing repeatedly with deionized water and acetone in sequence, placing in deionized water, ultrasonically treating at 500-600 W for 20-30 minutes, vacuum drying, and immersing in anhydrous ethanol to obtain an activated titanium substrate; S4, dispersing copper nitrate in methanol aqueous solution, placing it under 400-500W for ultrasonic treatment, after the reaction solution turns blue, adding 2-hydroxy-p-dibenzoic acid, stirring at 150-180rpm for reaction at room temperature for 2-3h, standing for 12-16h, centrifuging at 5000rpm for 5min, collecting the precipitate, washing it with deionized water and anhydrous ethanol, and vacuum drying to obtain Cu-MOF; wherein the mass concentration of the copper nitrate in the methanol aqueous solution is 15-20g / L; the mass concentration of the 2-hydroxy-p-dibenzoic acid in the methanol aqueous solution is 8-10g / L; S5, dispersing the Cu-MOF prepared in step S4 in deionized water, stirring at 600-800 rpm, and obtaining a Cu-MOF dispersion after being in a uniform suspension state, adding a ruthenium chloride solution and an iridium chloride solution, stirring at 800-1000 rpm, reacting for 18-24 hours, filtering and collecting the precipitate, repeatedly washing with deionized water and acetone, and freeze-drying to obtain RuIrCu-MOF; wherein the mass concentration of the Cu-MOF in deionized water is 0.2%-0.4%; the mass concentration of the ruthenium chloride in deionized water in the ruthenium chloride solution is 5-10 g / L; the mass concentration of the iridium chloride in deionized water in the iridium chloride solution is 10-15 g / L; the added volume of the ruthenium chloride solution is 7%-10% of the volume of the Cu-MOF dispersion; the added volume of the iridium chloride solution is 5%-7% of the volume of the Cu-MOF dispersion; S6, dispersing the RuIrCu-MOF prepared in step S5 in DMF solvent, adding thioacetamide, mixing evenly, immersing the activated titanium substrate prepared in step S3 in the reaction system, transferring to a high-pressure reactor, adjusting the temperature to 220-250° C., reacting for 20-28 hours, cooling, washing with anhydrous ethanol and deionized water, and vacuum drying to obtain a modified titanium substrate; wherein the mass concentration of the RuIrCu-MOF in the DMF solvent is 1-1.5 g / L; the mass ratio of the RuIrCu-MOF to thioacetamide is 0.6-0.8:1; S7. Prepare 2-methylimidazole and cobalt nitrate hexahydrate solution respectively, mix the two to form a uniform reaction system, immerse the modified titanium substrate prepared in step S6 in the reaction system, place it in an oscillator and oscillate it at a speed of 120 rpm for 1.5-2.5 hours, take out the modified titanium substrate, wash it with deionized water and anhydrous ethanol, place it in a high-pressure reactor, and in an argon atmosphere, increase the temperature to 600-700°C at 10°C / min, and keep it warm for 2-3 hours to obtain an electrocatalytic plate.

2. The method for preparing the landfill leachate electrocatalytic plate according to claim 1, characterized in that: In step S2, the alkaline washing solution includes the following components: 40-50 g / L sodium carbonate, 5-10 g / L sodium hydroxide, 60-80 g / L sodium phosphate, 1-1.5 g / L sodium dodecyl sulfate, and 1-2 g / L hydrogen peroxide; in step S3, the mass concentration of oxalic acid in deionized water in the oxalic acid solution is 80-100 g / L.

3. The method for preparing the landfill leachate electrocatalytic plate according to claim 2, characterized in that: In step S7, in the 2-methylimidazole solution, the mass concentration of 2-methylimidazole in methanol is 40-50 g / L; in the cobalt nitrate hexahydrate solution, the mass concentration of cobalt nitrate hexahydrate in methanol is 50-60 g / L; and the mass ratio between the 2-methylimidazole and the cobalt nitrate hexahydrate is 0.8-1:1-1.

2.

4. Landfill leachate electrocatalytic plate, characterized by: Prepared according to the preparation method according to any one of claims 1 to 3.

5. Application of electrocatalytic plates for landfill leachate, characterized by: The use of the electrocatalytic plate prepared by the preparation method according to any one of claims 1 to 3 in an electrocatalytic oxidation treatment device for landfill leachate, wherein the electrocatalytic oxidation treatment device comprises a plate group, an adaptive power supply, and a reaction tank.

6. The use of the landfill leachate electrocatalytic plate according to claim 5, characterized in that: The electrocatalytic plate is used as the anode plate of the electrocatalytic oxidation treatment device for landfill leachate; the cathode plate material includes at least one of a carbon plate, a 316 stainless steel plate and a pure titanium plate.

7. The use of the landfill leachate electrocatalytic plate according to claim 6, characterized in that: The spacing between the electrocatalytic plate and the cathode plate in the plate group is 1-4 cm; the plate surface area of ​​the electrocatalytic plate and the cathode plate is 0.1-0.08 m 2 .

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