High-hydrophobicity cerium manganese oxide modified PbO2 electrode and method for degrading micro-plastics in water through ultrasonic-assisted electrocatalytic oxidation based on high-hydrophobicity cerium manganese oxide modified PbO2 electrode
By modifying a PbO2 electrode with highly hydrophobic cerium manganese oxide and using ultrasound-assisted electrocatalytic oxidation, the problem of the difficulty in degrading microplastics in water was solved, and a highly efficient microplastic degradation effect was achieved.
Patent Information
- Application Number
- CN202410587520.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-13
- Publication Date
- 2025-11-14
AI Technical Summary
Existing technologies are insufficient for efficiently degrading microplastics in water, and traditional biotechnology has minimal effect, making it urgent to develop economical and efficient water treatment processes.
A highly hydrophobic cerium manganese oxide-modified PbO2 electrode was used to degrade microplastics in water by combining it with an ultrasound-assisted electrocatalytic oxidation method. The process involved preparing a highly hydrophobic cerium manganese oxide-modified PbO2 electrode and performing electrocatalytic oxidation degradation under ultrasonic radiation.
It significantly improves the degradation efficiency of microplastics. Ultrasonic-assisted electrocatalytic oxidation has more than twice the degradation efficiency of ordinary electrodes, achieving a highly efficient microplastic degradation effect.
Smart Images
Figure CN120943352A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of water treatment technology and electrochemistry, specifically relating to an electrocatalytic oxidation electrode and a method for degrading microplastics in water, more specifically, an electrode and method for ultrasonic-assisted electrocatalytic oxidation degradation of microplastics in water. Background Technology
[0002] Plastic products are widely used worldwide due to their advantages such as stable properties, lightweight portability, and low cost. Since the 1950s, global plastic production has grown rapidly. Statistics show that 348 million tons of plastic were produced globally in 2017. However, only 21% of plastic is recycled or incinerated (Law, K.L.A.Nu. Rev. Mari. Sci. 2017, 9, 205-229). Most plastics will form microplastics (MPs) with a particle size of less than 5 mm under environmental influences such as mechanical wear, photochemical oxidation, biodegradation, and hydrolysis. In addition, cosmetics, detergents, and pharmaceutical carriers also contain a large number of plastic microbeads. Due to their wide range of sources, long lifespan, tiny size, and easy migration, microplastics have spread all over the world, affecting land, lakes, oceans, and even polar glaciers (Yu, F.; Yang, C., Huang, G., Zhou, T., Zhao, Y., Ma, J. Sci. Total Environ. 2020, 721, 137729-137736). In addition to their large specific surface area, strong hydrophobicity, and adsorption properties, microplastics can adsorb various toxic organic compounds and heavy metal ions in water. Once ingested by aquatic organisms, they not only have direct negative impacts on the organisms themselves, but also accumulate and bioaccumulate through the food chain over a long period, eventually ending up ingested by humans, thus adversely affecting human health (Huang, W., Song, B., Liang, J., Niu, Q., Zeng, G., Shen, M., Deng, J., Luo, Y., Wen, X., Zhang, YJ Hazard. Mater. 2020, 405, 124187-124225). Therefore, microplastics already pose a real threat to the stability and balance of ecosystems and human health.
[0003] However, microplastics, as a class of high-molecular-weight polymers, are chemically stable and difficult to degrade spontaneously in the natural environment. It has been reported that even under optimal laboratory exposure conditions, only 0.1% of the carbon in polyethylene polymers is converted into carbon dioxide annually through biodegradation (Andrady, A.L. Biodegradation of plastics: Monitoring what happens. 1998). Traditional biotechnologies have also shown negligible effects on the degradation of microplastics, highlighting the urgent need to develop economical, efficient, and practical water treatment processes. Therefore, improving the degradation efficiency of microplastics in water is a key technical problem that needs to be solved. Summary of the Invention
[0004] To improve the degradation effect of microplastics, this invention provides a highly hydrophobic cerium manganese oxide modified PbO2 electrode, and based on this electrode, proposes a method for ultrasonic-assisted electrocatalytic oxidation degradation of microplastics in water.
[0005] The technical solution adopted in this invention is as follows:
[0006] A highly hydrophobic cerium manganese oxide modified PbO2 electrode is composed of a titanium plate, a SnO2-Sb2O3 bottom layer on the titanium plate substrate, an α-PbO2 intermediate layer on the SnO2-Sb2O3 bottom layer, and a highly hydrophobic cerium manganese oxide modified β-PbO2 active layer on the α-PbO2 intermediate layer.
[0007] The preparation method of the highly hydrophobic cerium manganese oxide modified PbO2 electrode includes the following steps:
[0008] Step 1: Preparation of cerium manganese oxide;
[0009] Step 2: Pretreatment of the titanium plate substrate;
[0010] Step 3: Thermal deposition of SnO2-Sb2O3 bottom layer;
[0011] Step 4: Electrodeposition of an α-PbO2 intermediate layer;
[0012] Step 5: Prepare a highly hydrophobic cerium manganese oxide modified β-PbO2 active layer;
[0013] The specific steps in step five for preparing the highly hydrophobic cerium manganese oxide modified β-PbO2 active layer are as follows:
[0014] 1) Preparation of β-PbO2 electroplating solution containing cerium manganese oxide and sodium dodecylbenzenesulfonate: Add 0.5 mol lead nitrate, 0.05 mol sodium fluoride, 1 mol concentrated nitric acid, and 0.001-0.005 g sodium dodecylbenzenesulfonate to an appropriate amount of deionized water, stir until completely dissolved, and then adjust the volume to 1 L to obtain β-PbO2 electroplating solution. Before electroplating, take 100 mL of β-PbO2 electroplating solution and add 0.001-0.01 g of cerium manganese oxide prepared in step 1, and stir until the cerium manganese oxide is uniformly dispersed in the electroplating solution;
[0015] 2) Using the titanium plate substrate with the α-PbO2 interlayer prepared in step 4 as the anode, and a stainless steel plate of the same area as the cathode, they are placed face-to-face vertically in 100 mL of the β-PbO2 electroplating solution containing cerium manganese oxide and sodium dodecylbenzenesulfonate prepared in step 1). The electrode spacing is 3 cm, and electrodeposition is carried out under magnetic stirring at 300 rpm and a current density of 15 mA / cm². 2 The electrodeposition process was carried out at a temperature of 65℃ for 1 hour. After electrodeposition, the electrode was rinsed with deionized water to obtain a highly hydrophobic cerium manganese oxide modified PbO2 electrode.
[0016] Preferably, the step of preparing cerium manganese oxide in step one is as follows:
[0017] Weigh 0.9 mmol of cerium trichloride heptahydrate and 2.1 mmol of manganese acetate tetrahydrate, dissolve them in 10 mL of deionized water, add 3 mmol of trisodium citrate dihydrate, and mix with 40 mL of ethylene glycol containing 0.4 g of urea. After sonicating the mixture for 60 minutes, transfer it to a high-pressure reactor lined with 100 mL of polytetrafluoroethylene and heat-treat it at 200 °C for 10 hours. After naturally cooling to room temperature, collect the precipitate by centrifugation, and then calcine the precipitate in a muffle furnace at 500 °C for 2 hours to obtain cerium manganese oxide.
[0018] Preferably, the pretreatment step of the titanium plate substrate in step two is as follows:
[0019] The titanium substrate was polished sequentially with 120-grit, 600-grit, and 1200-grit sandpaper until it exhibited a silvery-white metallic luster. The polished titanium substrate was then ultrasonically cleaned in acetone and deionized water for 10 minutes to remove oil and other impurities from the substrate surface. The cleaned titanium substrate was then immersed in oxalic acid etching solution and etched at 90°C for 4 hours. Afterward, it was rinsed with deionized water to complete the pretreatment of the titanium substrate. The oxalic acid etching solution was prepared by heating and dissolving 200g of oxalic acid in 1L of deionized water.
[0020] More preferably, the titanium plate substrate after pretreatment in step two is stored in an oxalic acid preservation solution and then rinsed with deionized water before use; the oxalic acid preservation solution is prepared by dissolving 10g of oxalic acid in 1L of deionized water.
[0021] Preferably, the step of thermally depositing the SnO2-Sb2O3 underlayer in step three is as follows:
[0022] 1) Dissolve 100g tin tetrachloride, 10g antimony trichloride and 66mL concentrated hydrochloric acid in 200mL isopropanol, and make up to 500mL with isopropanol to prepare a coating solution.
[0023] 2) Apply the prepared coating solution evenly to the titanium plate substrate that has been pretreated in step 2, then put it into an electric drying oven at 120°C and dry it for 10 minutes. Then put the dried titanium plate substrate into a muffle furnace at 550°C and bake it for 10 minutes.
[0024] 3) Repeat step 2) 10-12 times, and on the last time, extend the calcination time in the muffle furnace to 1 hour, and then cool naturally to room temperature to obtain a titanium plate substrate with a SnO2-Sb2O3 underlayer.
[0025] Preferably, the step of electrodepositing the α-PbO2 intermediate layer in step four is as follows:
[0026] 1) Slowly add 3.5 mol sodium hydroxide to 900 mL of deionized water. After it is completely dissolved, add 0.1 mol lead monoxide, heat and stir until it is completely dissolved, cool to room temperature and make up to 1 L to prepare α-PbO2 electroplating solution.
[0027] 2) Using the titanium substrate with the SnO2-Sb2O3 underlayer obtained in step 3 as the anode and a stainless steel plate of the same area as the cathode, they are placed vertically face-to-face in 100 mL of α-PbO2 electroplating solution with an electrode spacing of 3 cm. An α-PbO2 intermediate layer is electrodeposited under magnetic stirring at 300 rpm at a current density of 3 mA / cm². 2 The temperature was 40℃ and the electrodeposition time was 1 hour. After electrodeposition, the substrate was rinsed with deionized water to obtain a titanium plate substrate with an α-PbO2 intermediate layer.
[0028] The method for ultrasonic-assisted electrocatalytic oxidation degradation of microplastics in water using a PbO2 electrode modified with the highly hydrophobic cerium manganese oxide of this invention comprises the following steps:
[0029] A highly hydrophobic cerium manganese oxide-modified PbO2 electrode was used as the anode, and a stainless steel sheet of equal area was used as the cathode. The electrodes were placed face-to-face in a quartz bath containing 150 mL of microplastics and sodium sulfate solution (sodium sulfate concentration 0.01-0.1 mol / L) with a 1 cm distance between them. The electrodes were operated under ultrasonic assistance at a frequency of 40-100 kHz and a power of 200-700 W, with a current density set at 10-50 mA / cm². 2 Microplastics in water are degraded by electrocatalytic oxidation under constant current conditions.
[0030] Preferably, the constant current is provided by a DC regulated power supply, and the ultrasonic assistance is provided by an ultrasonic cleaner.
[0031] More preferably, the temperature for electrocatalytic oxidation degradation of microplastics in water is 30-100℃.
[0032] This invention has the following characteristics:
[0033] (1) The β-PbO2 active layer of the PbO2 electrode prepared in this invention contains cerium manganese oxide and transition metal oxide MnO2, which adjusts the oxygen defect concentration of CeO2 within a wide range, changes the oxygen storage and release capacity, and is used to modify the PbO2 electrode to improve the electrode's ability to generate ·OH free radicals.
[0034] (2) The cerium manganese oxide modified PbO2 electrode prepared in this invention has high hydrophobicity, which allows a large number of ·OH free radicals generated on the surface of the cerium manganese oxide modified PbO2 electrode to quickly enter the solution during the electrocatalytic oxidation process, thus avoiding the waste of a large number of ·OH free radicals by the oxygen evolution side reaction.
[0035] (3) This invention uses ultrasound-assisted electrocatalytic oxidation to degrade microplastics in water. When the aqueous solution is irradiated by ultrasound, cavitation bubbles with a very short lifespan are generated. These tiny bubbles will gradually increase in size until they reach a critical value during continuous compression and expansion cycles. Further compression will cause the bubbles to collapse. At the moment of collapse, not only will a large amount of active substances be generated, but also a large amount of heat will be generated, thereby forming regional hot spots in the tiny space around the bubbles, generating extremely high temperatures and pressures. Such extreme conditions can accelerate the reaction between ·OH free radicals and microplastics and promote the entry of ·OH free radicals into the interior of microplastic particles, thereby improving the degradation efficiency of microplastics. Attached Figure Description
[0036] Figure 1 The image shows a scanning electron microscope (SEM) image and hydrophilic angle image of a common lead dioxide electrode.
[0037] Figure 2 The images show scanning electron microscope (SEM) and hydrophilic angle images of the highly hydrophobic cerium manganese oxide-modified lead dioxide electrode described in this invention. Detailed Implementation
[0038] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments.
[0039] Example 1:
[0040] (1) Weigh 0.9 mmol of cerium trichloride heptahydrate and 2.1 mmol of manganese acetate tetrahydrate, dissolve them in 10 mL of deionized water, add 3 mmol of trisodium citrate dihydrate, and mix with 40 mL of ethylene glycol containing 0.4 g of urea. After sonicating the mixture for 60 minutes, transfer it to a high-pressure reactor lined with 100 mL of polytetrafluoroethylene and heat-treat it at 200 °C for 10 hours. After naturally cooling to room temperature, collect the precipitate by centrifugation, and then calcine the precipitate in a muffle furnace at 500 °C for 2 hours to obtain cerium manganese oxide.
[0041] (2) Polish the titanium plate substrate (30 mm × 50 mm × 0.8 mm) with 120 grit, 600 grit and 1200 grit sandpaper in sequence until the titanium plate substrate has a silvery-white metallic luster. Place the polished titanium plate substrate in acetone and deionized water for ultrasonic cleaning for 10 minutes to remove oil and other impurities on the surface of the substrate. Then immerse the ultrasonically cleaned titanium substrate in oxalic acid etching solution (oxalic acid etching solution is 150 g of oxalic acid heated and stirred and dissolved in 1 liter of deionized water) and etch at 90°C for 4 hours. Take it out, rinse it with deionized water and store it in oxalic acid preservation solution (oxalic acid preservation solution is 10 g of oxalic acid dissolved in 1 liter of deionized water).
[0042] (3) Dissolve 100g tin tetrachloride, 10g antimony trichloride, and 66mL concentrated hydrochloric acid in 200mL isopropanol, and dilute to 500mL with isopropanol to prepare a coating solution. Apply the prepared coating solution evenly to the titanium plate substrate pretreated in step (1), and then dry it in an electric drying oven at 120℃ for 10 minutes. Then, place the dried titanium plate substrate in a muffle furnace at 550℃ and bake it for 10 minutes. Repeat this step 10 times, with the last baking time in the muffle furnace being 1 hour. Then, allow it to cool naturally to room temperature to obtain a titanium plate substrate with a SnO2-Sb2O3 underlayer.
[0043] (4) Using the titanium plate substrate with the thermally deposited SnO2-Sb2O3 underlayer prepared in step (3) as the anode and a stainless steel plate of the same area as the cathode, they are placed vertically face to face in 100 mL of α-PbO2 electroplating solution containing 0.1 mol / L lead monoxide and 3.5 mol / L sodium hydroxide, with an electrode spacing of 3 cm. An α-PbO2 intermediate layer is electrodeposited under magnetic stirring at 300 rpm at a current density of 3 mA / cm². 2The electrodeposition process was carried out at a temperature of 40℃ for 1 hour. After electrodeposition, the electrode surface was rinsed clean with deionized water to obtain a titanium plate substrate with an α-PbO2 intermediate layer.
[0044] (5) Using the titanium plate substrate with the α-PbO2 interlayer prepared in step (4) as the anode and a stainless steel plate of the same area as the cathode, they are placed face-to-face vertically in 100 mL of β-PbO2 electroplating solution containing 0.5 mol / L lead nitrate, 0.05 mol / L sodium fluoride, 1 mol / L nitric acid, 0.056 g / L cerium manganese oxide, and 0.003 g / L sodium dodecylbenzenesulfonate. The electrode spacing is 3 cm. The α-PbO2 interlayer is electrodeposited under magnetic stirring at 300 rpm and a current density of 15 mA / cm². 2 The electrodeposition temperature was 65℃, and the electrodeposition time was 1 hour. After electrodeposition, the electrode was rinsed with deionized water to obtain a highly hydrophobic cerium manganese oxide modified PbO2 electrode. Its scanning electron microscope (SEM) image and hydrophilic angle image are shown below. Figure 2 As shown, by Figure 2 It can be seen that the prepared highly hydrophobic cerium manganese oxide modified PbO2 electrode has a smooth and dense surface, and the β-PbO2 crystal particle size is significantly smaller than that of ordinary lead dioxide electrode. The contact angle of water droplets on the electrode surface is 104°, and the hydrophobicity is significantly higher than that of ordinary PbO2 electrode.
[0045] Comparative Example
[0046] To facilitate comparison with the products of this invention, we prepared a common lead dioxide electrode and used it as the anode to construct an electrocatalytic oxidation system for degrading microplastics in water. The specific preparation method is as follows:
[0047] (1) Polish the titanium substrate (30mm×50mm×0.8mm) with 120-grit, 600-grit and 1200-grit sandpaper in sequence until the titanium substrate has a silvery-white metallic luster. Place the polished titanium substrate in acetone and deionized water in sequence for ultrasonic treatment for 10 minutes to remove oil and other impurities on the surface of the substrate. Then immerse the ultrasonically treated titanium substrate in oxalic acid etching solution (oxalic acid etching solution is prepared by dissolving 150g of oxalic acid in 1L of deionized water and heating and stirring until dissolved) and etch for 2 hours at 80℃ to slight boiling. After taking it out, place it in oxalic acid preservation solution (oxalic acid preservation solution is prepared by dissolving 10g of oxalic acid in 1L of deionized water and stirring until completely dissolved) for preservation.
[0048] (2) Add 20g of tin tetrachloride and 2g of antimony trichloride to a mixed solution of 13mL of 37% hydrochloric acid and 87mL of isopropanol, and stir until completely dissolved to prepare a coating solution. Take out the titanium substrate that was stored in the oxalic acid preservation solution in step (1), clean the surface with deionized water, apply the coating solution to the cleaned titanium substrate, dry it in an electric drying oven at 120°C for 10 minutes, and then place the dried titanium substrate in a muffle furnace at 550°C for 10 minutes. Repeat this process 10 times, with the last calcination time in the muffle furnace being 1 hour. Cool naturally to room temperature to obtain a titanium substrate with a tin antimony oxide (SnO2-Sb2O3) underlayer.
[0049] (3) Using the titanium substrate with tin-antimony oxide underlayer prepared in step (2) as the anode and a stainless steel plate of equal area as the cathode, an α-PbO2 intermediate layer was electrodeposited in 100 mL of an alkaline plating solution containing 0.1 mol / L lead monoxide and 3.5 mol / L sodium hydroxide. The electrodeposition current density was 3 mA / cm². 2 The deposition temperature was 40℃, and the deposition time was 1 hour. After washing with deionized water, a titanium matrix with an α-PbO2 interlayer was obtained.
[0050] (4) Using the titanium substrate with the α-PbO2 interlayer prepared in step (3) as the anode and a stainless steel plate of equal area as the cathode, a β-PbO2 surface active layer is electrodeposited in 100 mL of an acidic plating solution containing 0.5 mol / L lead nitrate, 0.05 mol / L sodium fluoride, and 1 mol / L nitric acid. The electrodeposition current density is 15 mA / cm². 2 The deposition temperature was 65℃, and the deposition time was 1 hour, resulting in a prepared ordinary lead dioxide electrode, as shown in the attached figure. Figure 1 As shown in the figure, a typical lead dioxide electrode is composed of a large number of pyramid-shaped lead dioxide crystal particles, and the contact angle of a water droplet on the electrode surface is 78°.
[0051] Effect verification:
[0052] A standard lead dioxide electrode prepared in the comparative example was used as the anode, and a stainless steel plate of equal area was used as the cathode. The electrode spacing was 1 cm. Polyvinyl chloride (PVC) microplastics in water were electrocatalytically oxidized. The PVC microplastic concentration was 82 mg / L. 0.08 mol / L sodium sulfate was used as the supporting electrolyte. The solution volume was 150 mL, the temperature was 60 °C, and a constant current density of 57 mA / cm² was provided by a DC regulated power supply. 2 After 6 hours of electrolysis, the weight loss rate of polyvinyl chloride microplastics was 35.76%.
[0053] The highly hydrophobic cerium manganese oxide-modified PbO2 electrode prepared in Example 1 was used as the anode, and a stainless steel plate of equal area was used as the cathode. The electrode spacing was 1 cm. Polyvinyl chloride (PVC) microplastics in water were electrocatalytically oxidized. The PVC microplastic concentration was 82 mg / L. 0.08 mol / L sodium sulfate was used as the supporting electrolyte. The solution volume was 150 mL, and a constant current density of 57 mA / cm² was provided by a DC regulated power supply. 2 Using an ultrasonic cleaner with ultrasonic assistance at a frequency of 40kHz, an ultrasonic power of 600W, and a temperature of 60℃, the weight loss rate of microplastics after 6 hours of electrolysis was 72.00%, which is 2.01 times that of the electrocatalytic oxidation system with a common lead dioxide electrode as the anode.
[0054] In the process of ultrasonic electrocatalytic oxidation of polyvinyl chloride microplastics, the ultrasonic power was changed to 240W. After 6 hours of electrolysis, the weight loss rate of the microplastics was 66.67%, which is 1.86 times that of the electrocatalytic oxidation system with ordinary lead dioxide electrode as anode.
[0055] As can be seen from the above comparison of effects, the highly hydrophobic cerium manganese oxide modified PbO2 electrode and the ultrasound-assisted electrocatalytic oxidation proposed in this invention significantly improve the efficiency of polyvinyl chloride microplastic degradation compared with ordinary lead dioxide electrode.
Claims
1. A highly hydrophobic cerium manganese oxide modified PbO2 electrode, characterized in that, It consists of a titanium plate, a SnO2-Sb2O3 substrate on the titanium plate, an α-PbO2 intermediate layer on the SnO2-Sb2O3 substrate, and a highly hydrophobic cerium manganese oxide modified β-PbO2 active layer on the α-PbO2 intermediate layer.
2. The method for preparing a highly hydrophobic cerium manganese oxide modified PbO2 electrode according to claim 1, characterized in that, The method includes the following steps: Step 1: Preparation of cerium manganese oxide; Step 2: Pretreatment of the titanium plate substrate; Step 3: Thermal deposition of SnO2-Sb2O3 bottom layer; Step 4: Electrodeposition of an α-PbO2 intermediate layer; Step 5: Prepare a highly hydrophobic cerium manganese oxide modified β-PbO2 active layer; The specific steps in step five for preparing the highly hydrophobic cerium manganese oxide-modified β-PbO2 active layer are as follows: 1) Preparation of β-PbO2 electroplating solution containing cerium manganese oxide and sodium dodecylbenzenesulfonate: Add 0.5 mol lead nitrate, 0.05 mol sodium fluoride, 1 mol concentrated nitric acid, and 0.001-0.005 g sodium dodecylbenzenesulfonate to an appropriate amount of deionized water, stir until completely dissolved, and then adjust the volume to 1 L to obtain β-PbO2 electroplating solution. Before electroplating, take 100 mL of β-PbO2 electroplating solution and add 0.001-0.01 g of cerium manganese oxide prepared in step 1, and stir until the cerium manganese oxide is evenly dispersed in the electroplating solution; 2) Using the titanium plate substrate with the α-PbO2 interlayer prepared in step 4 as the anode, and a stainless steel plate of the same area as the cathode, they are placed face-to-face vertically in 100 mL of the β-PbO2 electroplating solution containing cerium manganese oxide and sodium dodecylbenzenesulfonate prepared in step 1). The electrode spacing is 3 cm, and electrodeposition is carried out under magnetic stirring at 300 rpm and a current density of 15 mA / cm². 2 The electrodeposition process was carried out at a temperature of 65℃ for 1 hour. After electrodeposition, the electrode was rinsed with deionized water to obtain a highly hydrophobic cerium manganese oxide modified PbO2 electrode.
3. The method for preparing a highly hydrophobic cerium manganese oxide modified PbO2 electrode according to claim 1, characterized in that, The steps for preparing cerium manganese oxide in step one are as follows: Weigh 0.9 mmol of cerium trichloride heptahydrate and 2.1 mmol of manganese acetate tetrahydrate, dissolve them in 10 mL of deionized water, add 3 mmol of trisodium citrate dihydrate, and mix with 40 mL of ethylene glycol containing 0.4 g of urea. After sonicating the mixture for 60 minutes, transfer it to a high-pressure reactor lined with 100 mL of polytetrafluoroethylene and heat-treat it at 200 °C for 10 hours. After naturally cooling to room temperature, collect the precipitate by centrifugation, and then calcine the precipitate in a muffle furnace at 500 °C for 2 hours to obtain cerium manganese oxide.
4. The method for preparing a highly hydrophobic cerium manganese oxide modified PbO2 electrode according to claim 1, characterized in that, The pretreatment steps for the titanium plate substrate in step two are as follows: The titanium substrate was polished sequentially with 120-grit, 600-grit, and 1200-grit sandpaper until it exhibited a silvery-white metallic luster. The polished titanium substrate was then ultrasonically cleaned in acetone and deionized water for 10 minutes to remove oil and other impurities from the substrate surface. The cleaned titanium substrate was then immersed in oxalic acid etching solution and etched at 90°C for 4 hours. Afterward, it was rinsed with deionized water to complete the pretreatment of the titanium substrate. The oxalic acid etching solution was prepared by heating and dissolving 200g of oxalic acid in 1L of deionized water.
5. The method for preparing a highly hydrophobic cerium manganese oxide modified PbO2 electrode according to claim 4, characterized in that, The pretreated titanium plate substrate from step two is stored in an oxalic acid preservation solution and then rinsed with deionized water before use. The oxalic acid preservation solution is prepared by dissolving 10g of oxalic acid in 1L of deionized water.
6. The method for preparing a highly hydrophobic cerium manganese oxide modified PbO2 electrode according to claim 2, characterized in that, The steps in step three, including the thermal deposition of the SnO2-Sb2O3 sublayer, are as follows: 1) Dissolve 100g tin tetrachloride, 10g antimony trichloride and 66mL concentrated hydrochloric acid in 200mL isopropanol, and make up to 500mL with isopropanol to prepare a coating solution. 2) Apply the prepared coating solution evenly to the titanium plate substrate that has been pretreated in step 2, then put it into an electric drying oven at 120°C and dry it for 10 minutes. Then put the dried titanium plate substrate into a muffle furnace at 550°C and bake it for 10 minutes. 3) Repeat step 2) 10-12 times, and on the last time, extend the calcination time in the muffle furnace to 1 hour, and then cool naturally to room temperature to obtain a titanium plate substrate with a SnO2-Sb2O3 underlayer.
7. The method for preparing a highly hydrophobic cerium manganese oxide modified PbO2 electrode according to claim 2, characterized in that, The steps for electrodepositing the α-PbO2 intermediate layer in step four are as follows: 1) Slowly add 3.5 mol sodium hydroxide to 900 mL of deionized water. After it is completely dissolved, add 0.1 mol lead monoxide, heat and stir until it is completely dissolved, cool to room temperature and make up to 1 L to prepare α-PbO2 electroplating solution. 2) Using the titanium substrate with the SnO2-Sb2O3 underlayer obtained in step 3 as the anode and a stainless steel plate of the same area as the cathode, they are placed vertically face-to-face in 100 mL of α-PbO2 electroplating solution with an electrode spacing of 3 cm. An α-PbO2 intermediate layer is electrodeposited under magnetic stirring at 300 rpm and a current density of 3 mA / cm². 2 The temperature was 40℃ and the electrodeposition time was 1 hour. After electrodeposition, the substrate was rinsed with deionized water to obtain a titanium plate substrate with an α-PbO2 intermediate layer.
8. A method for ultrasonic-assisted electrocatalytic oxidation degradation of microplastics in water based on a highly hydrophobic cerium manganese oxide modified PbO2 electrode as described in claim 1, characterized in that, The specific steps of this method are as follows: A highly hydrophobic cerium manganese oxide-modified PbO2 electrode was used as the anode, and a stainless steel sheet of equal area was used as the cathode. The electrodes were placed face-to-face in a quartz bath containing 150 mL of microplastics and sodium sulfate solution (sodium sulfate concentration 0.01-0.1 mol / L) with a 1 cm distance between them. The electrodes were operated under ultrasonic assistance at a frequency of 40-100 kHz and a power of 200-700 W, with a current density set at 10-50 mA / cm². 2 Microplastics in water are degraded by electrocatalytic oxidation under constant current conditions.
9. The method for ultrasonic-assisted electrocatalytic oxidation degradation of microplastics in water according to claim 8, characterized in that, The constant current is provided by a DC regulated power supply, and the ultrasonic assistance is provided by an ultrasonic cleaner.
10. The method for ultrasonic-assisted electrocatalytic oxidation degradation of microplastics in water according to claim 8 or 9, characterized in that, The temperature range for electrocatalytic oxidation degradation of microplastics in water is 30-100℃.