Cu-Ce-at-gamma-Al2O3 (111) particle electrode and application thereof in degradation of 2, 4, 5-trichlorophenol wastewater

Abstract

The invention discloses a Cu-Ce [gamma]-Al2O3 (111) particle electrode and application of the Cu-Ce [gamma]-Al2O3 (111) particle electrode in degradation of 2, 4, 5-trichlorophenol wastewater, triethyl aluminum is taken as a raw material, polyvinylpyrrolidone is taken as a template agent, EDTA (ethylene diamine tetraacetic acid) is taken as a structural auxiliary agent, and a solvothermal method is adopted to prepare exposed (111) crystal face [gamma]-Al2O3; and then loading cerium and copper on the exposed (111) crystal face gamma-Al2O3 by adopting a multi-time impregnation method to obtain the Cu-Ce (at) gamma-Al2O3 (111) particle electrode. The Cu-Ce-at-gamma-Al2O3 (111) particle electrode is filled between the main cathode and the anode to realize a three-dimensional electrocatalytic oxidation reaction, the Cu-Ce-at-gamma-Al2O3 (111) particle electrode shows excellent electrochemical performance when applied to electrochemical degradation of 2, 4, 5-trichlorophenol wastewater, and the removal rate of the Cu-Ce-at-gamma-Al2O3 (111) particle electrode to the 2, 4, 5-trichlorophenol reaches 98.4%. The electrode has great application potential as an efficient electrochemical wastewater treatment method.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a Cu-Ce@γ-Al2O3(111) particle electrode and its application in degrading 2,4,5-trichlorophenol wastewater. Background Art

[0002] 2,4,5-Trichlorophenol is one of the widely used industrial compounds with a very large production scale. It is widely used in dye intermediates and the paper industry, and can also be used as a fungicide, preservative, herbicide, and solvent for polyester fibers. The 2,4,5-trichlorophenol used in these industries may pollute the environment. It has strong toxicity and persistence in the environment, and can pose a hazard to the human body through bioaccumulation in the food chain. Therefore, the US Environmental Protection Agency has listed 2,4,5-trichlorophenol as a priority pollutant. Many countries have also explicitly prohibited or restricted the use of chlorophenol chemicals including 2,4,5-trichlorophenol, and the discharge of wastewater containing 2,4,5-trichlorophenol is strictly controlled.

[0003] With the rapid development of industrialization in China, while promoting the economy, it has also brought harm to the ecosystem and environment, generating a large amount of wastewater with characteristics such as complex composition, high organic matter concentration, and difficult biodegradation. Electrochemical catalytic oxidation technology is a new type of electrochemical water treatment technology. However, traditional electrochemical catalytic oxidation technology has two defects: First, when using two-dimensional electrodes, the current efficiency is low, the chemical reaction is slow, and the power consumption is high, which is not suitable for the treatment of semi-coke wastewater with relatively low budget costs; the second is the existing improved technology, which generally makes the anode into a three-dimensional structure to improve the catalytic activity of the reaction, but the manufacturing cost is high, and the electrode surface is easily blocked by pollutants, resulting in the failure of catalytic activity. Summary of the Invention

[0004] The purpose of the present invention is to provide a Cu-Ce@γ-Al2O3(111) particle electrode with low cost, simple preparation method, and high catalytic activity, as well as the application of this particle electrode.

[0005] To achieve the above purpose, the Cu-Ce@γ-Al2O3(111) particle electrode provided by the present invention is prepared by the following steps:

[0006] Step 1: Dissolve triethylaluminum in ethylene glycol, add polyvinylpyrrolidone and EDTA, stir for 3 - 5 h to make them evenly mixed, then transfer the obtained mixed solution into a hydrothermal reactor lined with polytetrafluoroethylene, carry out a solvothermal reaction at 150 - 220 °C for 48 - 72 h, then carry out centrifugation, wash with deionized water and dry to obtain γ-Al2O3 with exposed (111) crystal plane (denoted as γ-Al2O3(111));

[0007] Step 2: Mix the cerium nitrate aqueous solution, copper nitrate aqueous solution, hydrochloric acid, and absolute ethanol evenly, then immerse the obtained solution in γ-Al2O3(111), stir and mix well for 3 - 5 h, perform vacuum filtration, dry, and then calcine at 550 - 600 °C for 4 - 6 h;

[0008] Step 3: Repeat the operation steps of Step 2 two to three times for the product calcined in Step 2 to obtain the Cu-Ce@γ-Al2O3(111) particle electrode.

[0009] In the above Step 1, it is preferred that the mass ratio of the triethylaluminum, polyvinylpyrrolidone, and EDTA is 1:0.6 - 0.8:0.1 - 0.2.

[0010] Furthermore, in the above Step 1, it is preferred to perform a solvothermal reaction at 170 - 200 °C for 48 - 72 h.

[0011] In the above Step 1, the drying temperature is 60 - 80 °C, and the drying time is 12 - 24 h.

[0012] In the above Step 2, it is preferred that the volume ratio of the cerium nitrate aqueous solution, copper nitrate aqueous solution, hydrochloric acid, and absolute ethanol is 1:0.5 - 1:0.7 - 1:1, where the concentration of cerium nitrate in the cerium nitrate aqueous solution is 6 - 8 mmol / L, the concentration of copper nitrate in the copper nitrate aqueous solution is 0.5 - 1 mmol / L, and the concentration of hydrochloric acid is 0.5 - 1 mmol / L.

[0013] Furthermore, in the above Step 2, it is preferred to calcine at 550 °C for 4 h.

[0014] In the above Step 2, it is preferred that the heating rate of the calcination is 3 - 8 °C / min.

[0015] The Cu-Ce@γ-Al2O3(111) particle electrode of the present invention can be used for the electrochemical catalytic oxidation degradation of 2,4,5-trichlorophenol wastewater. The specific method is as follows: Add the 2,4,5-trichlorophenol wastewater to a three-dimensional electrode reactor, which includes an anode, a cathode, and the Cu-Ce@γ-Al2O3(111) particle electrode arranged between the two electrodes; Add an electrolyte to the 2,4,5-trichlorophenol wastewater and mix well to make the concentration of the electrolyte in the 2,4,5-trichlorophenol wastewater 0.01 - 0.05 mol / L, then add hydrochloric acid to adjust the pH value to 2 - 6, and introduce air. Under the conditions of an electrode spacing of 15 - 25 mm, a cell voltage of 4 - 7 V, an air velocity of 0.5 - 0.7 L / min, and a temperature of 10 - 30 °C, perform the electrochemical catalytic oxidation degradation of 2,4,5-trichlorophenol.

[0016] Furthermore, the above anode is a stainless steel plate, the cathode is a graphite plate, and the electrolyte is Na2SO4.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. Using triethylaluminum as the raw material, polyvinylpyrrolidone as the template agent, and EDTA as the structure assistant, γ-Al2O3 exposing the (111) crystal plane is prepared by the solvothermal method. The γ-Al2O3 exposing the (111) crystal plane has strong Lewis acid and Brønsted acid sites. By impregnating with Cu and Ce elements, the agglomeration of the supported metals can be prevented, enabling better dispersion, and its D band is deeper, which can improve the catalytic performance.

[0019] 2. The Cu-Ce@γ-Al2O3(111) particle electrode of the present invention is used in a three-dimensional electrode reactor for the electrochemical catalytic oxidation degradation of 2,4,5-trichlorophenol wastewater, and can effectively degrade 2,4,5-trichlorophenol at room temperature, with a removal rate reaching 98.4%. Brief Description of the Drawings

[0020] Figure 1 It is the SEM image of γ-Al2O3(111) prepared in Example 1.

[0021] Figure 2 FT-IR images of γ-Al2O3(111) prepared in Example 1 adsorbing pyridine at different temperatures.

[0022] Figure 3 It is the XRD image of γ-Al2O3(111) and Cu-Ce@γ-Al2O3(111) prepared in Example 1.

[0023] Figure 4 It is the structural schematic diagram of the three-dimensional electrode reactor. Among them, 1: power supply, 2: anode, 3: cathode, 4: support, 5: electrolytic cell, 6: particle electrode, 7: magnetic stir bar, 8: magnetic stirrer.

[0024] Figure 5 It is the influence of the electrode spacing on the degradation of 2,4,5-trichlorophenol.

[0025] Figure 6 It is the influence of the electrolyte concentration on the degradation of 2,4,5-trichlorophenol.

[0026] Figure 7 It is the influence of pH on the degradation of 2,4,5-trichlorophenol.

[0027] Figure 8 It is the influence of the degradation temperature on the degradation of 2,4,5-trichlorophenol.

[0028] Figure 9 It is the influence of the electrolytic cell voltage on the degradation of 2,4,5-trichlorophenol.

[0029] Figure 10 It is the influence of the concentration of 2,4,5-trichlorophenol on degradation. Specific implementation manners

[0030] The present invention will be further described in detail below in conjunction with the drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments only.

[0031] Example 1

[0032] Step 1: Dissolve 20 g of triethylaluminum in 100 mL of ethylene glycol, add 15 g of polyvinylpyrrolidone and 2 g of EDTA, and stir for 3 h to make it evenly stirred; then transfer the obtained mixed solution into a hydrothermal autoclave with a polytetrafluoroethylene liner, put it into a drying oven, carry out a solvothermal reaction at 180 °C for 72 h, then carry out centrifugation, wash with deionized water and dry at 60 °C for 18 h to obtain γ-Al2O3(111). It can be seen that the obtained γ-Al2O3(111) is in the shape of cluster long bars, and the surface is flat and the morphology is complete. From Table 1, it can be obtained that the (111) crystal plane of γ-Al2O3 has the highest surface energy and O-Al bond density among all its crystal planes. Therefore, the (111) crystal plane of γ-Al2O3 also has the highest hydroxyl density and the strongest B acid strength, and has the highest L acid strength after dehydration. Figure 1 The adsorption effect diagrams of the prepared γ-Al2O3(111) on pyridine at 50 °C, 100 °C, and 150 °C respectively. It can be seen that there are strong diffraction peaks at 1450 and 1540, indicating that the prepared γ-Al2O3(111) has strong L acid and B acid sites. Figure 2

[0033] Table 1 The number (N) of O-Al bonds and surface energy (E) of each crystal plane of γ-Al2O3

[0034]

[0035] Step 2: Mix 40 mL of 7.14 mmol / L cerium nitrate aqueous solution, 25 mL of 0.5 mmol / L copper nitrate aqueous solution, 30 mL of 0.5 mmol / L hydrochloric acid, and 40 mL of absolute ethanol evenly, then immerse the obtained solution into 10 g of γ-Al2O3(111), fully mix for 4 h under magnetic stirring, use a water vacuum circulator for suction filtration, dry the filter cake at 95 °C for 12 h, and then heat it in a muffle furnace at a heating rate of 5 °C / minute to 550 °C and calcine for 4 h.

[0036] Step 3: Repeat the operation steps of Step 2 twice for the product calcined in Step 2 to obtain Cu-Ce@γ-Al2O3(111) particle electrodes.

[0037] Figure 3 ​XRD characteristic diffraction patterns of the prepared γ-Al2O3(111) and Cu-Ce@γ-Al2O3(111) are shown. The 2θ angles at 37.4°, 45.9°, and 66.8° correspond to the (311), (400), and (440) crystal planes of γ-Al2O3, respectively, indicating that the prepared γ-Al2O3 has good crystallinity. The 2θ angles at 36.9°, 37.6°, and 60.4° correspond to the (101), (002), and (112) crystal planes of Ce, respectively, indicating successful Ce loading. The 2θ angles at 35.4°, 65.7°, and 67.9° correspond to the (002), (022), and (113) crystal planes of Cu, respectively, indicating successful Cu loading.

[0038] Example 2

[0039] 15 g of 2,4,5-trichlorophenol was dissolved in deionized water to prepare a 2,4,5-trichlorophenol aqueous solution with a concentration of 150 mg / L as simulated wastewater. The Figure 4 shown three-dimensional electrode reactor was used. The anode was a stainless steel plate (d = 7 cm), and the cathode was a graphite plate ( ). The anode and cathode were coaxially placed. 5 g of Cu-Ce@γ-Al2O3(111) particle electrodes were filled between the anode and the cathode. Then, 100 mL of simulated wastewater was added to the three-dimensional electrode reactor, and Na2SO4 was added as an electrolyte and mixed thoroughly to make the concentration of Na2SO4 in the simulated wastewater 0.025 mol / L. Then, hydrochloric acid was added to adjust the pH value to 3, and air was introduced. Under the conditions of an electrode spacing of 20 mm, a cell voltage of 6 V, an air velocity of 0.5 L / min, and a temperature of 25 °C, electrochemical catalytic oxidation was carried out to degrade 2,4,5-trichlorophenol for 90 min. Samples were taken every 15 min, and the COD and NH3-N values of the simulated wastewater were measured using a multi-parameter water quality rapid detector. The results showed that the removal rate of 2,4,5-trichlorophenol reached 98.4%.

[0040] To determine the process conditions of the present invention, the effects of factors such as pH value, electrolyte Na2SO4 dosage, electrolytic cell voltage, and temperature on the degradation of 2,4,5-trichlorophenol in the simulated wastewater were investigated respectively. The specific experiments are as follows:

[0041] (1) Effect of electrode spacing on the degradation of 2,4,5-trichlorophenol

[0042] The electrode spacing is one of the most common design parameters of electrochemical systems, and its change is related to the electrolyte resistance between the electrodes. Under the conditions of a 2,4,5-trichlorophenol concentration of 150 mg / L, an electrolyte concentration of 0.05 mol / L, a pH value of 3, a cell voltage of 6.5 V, an air velocity of 0.5 L / min, and a temperature of 25 °C in the simulated wastewater, the effect of different electrode spacings on the degradation of 2,4,5-trichlorophenol in the simulated wastewater was investigated. The results are shown in Figure 5 .

[0043] It can be seen from Figure 5 that after 90 min of electrolysis, when the electrode spacing was shortened from 30 mm to 20 mm, the average removal rate of 2,4,5-trichlorophenol increased from 87.6% to 98.4%. This is because the electrolyte resistance is proportional to the electrode distance, and a larger electrode spacing will increase the resistance of ion movement, thereby reducing the current utilization efficiency and mass transfer efficiency. When the electrode spacing is less than 20 mm, it can be seen that changing the electrode spacing has little effect on the average removal rate of 2,4,5-trichlorophenol. However, too small an electrode spacing will cause the degradation products to easily adsorb on the electrodes, resulting in serious surface passivation and thus increasing the operating cost. Therefore, the optimal electrode spacing is 20 mm.

[0044] (2) Effect of Na2SO4 electrolyte concentration on the degradation of 2,4,5-trichlorophenol

[0045] Under the conditions of a 2,4,5-trichlorophenol concentration of 150 mg / L, a pH value of 3, a cell voltage of 6.5 V, an electrode spacing of 20 mm, an air velocity of 0.5 L / min, and a temperature of 25 °C in the simulated wastewater, the effect of the Na2SO4 electrolyte concentration on the degradation of 2,4,5-trichlorophenol in the simulated wastewater was investigated. The results are shown in Figure 6 .

[0046] Figure 6It shows that due to the poor conductivity when there is a lack of electrolyte in the simulated wastewater, only 47.6% of 2,4,5-trichlorophenol is removed after 90 minutes of electrocatalytic degradation. When the electrolyte content reaches 0.025 mol / L, the removal rate of 2,4,5-trichlorophenol increases to 97.6%. When the electrolyte concentration reaches 0.05 mol / L, the removal rate of 2,4,5-trichlorophenol is 82.1%. When the electrolyte concentration continues to rise, the removal rate of 2,4,5-trichlorophenol decreases. This is because when the concentration of the electrolyte Na2SO4 in the system is low, the conductivity of the solution is also very low, which results in a very small reaction current in the reactor and a very slow reaction rate. Therefore, the treatment effect is not so strong. As the electrolyte concentration gradually increases, the conductivity of the system increases, and the removal rate significantly increases, which accelerates the ion migration rate in the solution and the rate of the electrochemical reaction, leading to the rapid oxidative degradation of 2,4,5-trichlorophenol and other intermediate products. However, if the concentration of the electrolyte Na2SO4 is too high, the removal efficiency of the 2,4,5-trichlorophenol wastewater will gradually decrease. At this time, in addition to the reaction current in the solution, the bypass current and the short-circuit current will both increase, which results in a steady decline in the current efficiency. The side reaction may consume a large amount of energy in the system at the same time, which will increase the temperature of the reaction solution. In addition to the above factors, excessive electrolyte may also affect the induced potential on the surface of the particle electrode. As the electrolyte concentration increases, the interaction and association of ions are improved and enhanced, yet the conductivity of the solution is affected. Since adding too much electrolyte is not cost-effective, an electrolyte concentration of 0.025 mol / L is selected. Too much electrolyte will also adsorb on the electrode surface, hindering the formation of active chemical substances.

[0047] (3) Influence of pH on the degradation of 2,4,5-trichlorophenol

[0048] The three-dimensional electrode system is mainly affected by the pH value of the wastewater, which has an impact on the charge characteristics between the organic matter and the water treatment material. Using 0.5 mol / L aqueous H2SO4 solution and NaOH aqueous solution to adjust different pH values, under the conditions that the concentration of 2,4,5-trichlorophenol in the simulated wastewater is 150 mg / L, the concentration of the electrolyte is 0.025 mol / L, the cell voltage is 6.5 V, the electrode spacing is 20 mm, the air velocity is 0.5 L / min, and the temperature is 25 °C, the influence of different pH values on the degradation of 2,4,5-trichlorophenol in the simulated wastewater is investigated, and the results are shown in Figure 7 .

[0049] Figure 7It shows that when the pH values are 3, 6, 9, and 12, after 90 minutes of the degradation reaction, the removal rates are 97.6%, 74.4%, 84.2%, and 90.1% respectively. When pH = 3 and the degradation time reaches 90 minutes, the three-dimensional electrode has the best removal effect on 2,4,5-trichlorophenol at this time. The main reasons are as follows: Under acidic conditions, on the one hand, the oxygen evolution potential of the anode is relatively high, which can effectively inhibit the occurrence of side reactions and is beneficial to improving the removal effect of 2,4,5-trichlorophenol; on the other hand, the electrochemical reaction that easily generates H2O2 occurs at the cathode, promoting the generation of ·OH and increasing the removal rate of 2,4,5-trichlorophenol. At the same time, under this condition, the hydroxyl radical will also be inhibited, reducing the generation of side reactions. Therefore, under acidic conditions, it is more conducive to the degradation of 2,4,5-trichlorophenol. Similarly, when pH = 12, the degradation effect is second only to that at pH = 3 because alkaline conditions are conducive to the generation of hydroxyl radicals, thereby efficiently degrading 2,4,5-trichlorophenol. However, because its energy consumption is higher than that of the reaction at pH = 3, the current efficiency decreases, and the electrocatalytic degradation of the three-dimensional electrode with particle electrodes is very different from that of the two-dimensional electrode, which is also one of the reasons for this phenomenon. The pH value has a great influence on the existence state of 2,4,5-trichlorophenol in the aqueous solution and the dissolution of the active components in the particle electrode, thus affecting the removal effect. From the perspective of treatment cost, the optimal pH value for treating 2,4,5-trichlorophenol is 3.

[0050] (4) Influence of temperature on the degradation of 2,4,5-trichlorophenol

[0051] In the simulated wastewater, the concentration of 2,4,5-trichlorophenol is 150 mg / L, the concentration of the electrolyte is 0.025 mol / L, the pH value is 3, the cell voltage is 6.5 V, the electrode plate spacing is 20 mm, and the air velocity is 0.5 L / min. Electrolysis is carried out at 10, 25, 30, and 40 °C respectively to investigate the influence of temperature on the degradation of 2,4,5-trichlorophenol in the simulated wastewater. The results are shown in Figure 8 .

[0052] Figure 8The results show that temperature has an obvious effect on the electrocatalytic oxidation of the three-dimensional electrode. With the increase of temperature, the removal rate of 2,4,5-trichlorophenol also increases in different dimensions. Compared with the degradation temperature of 10 °C, the removal rate of 2,4,5-trichlorophenol has a significant increase when the degradation temperature is 25 °C. This indicates that increasing the temperature helps to improve the degradation rate of 2,4,5-trichlorophenol and the current efficiency of electrocatalytic degradation. The reason is that the increase in temperature accelerates the diffusion of 2,4,5-trichlorophenol at the electrode-solution interface, which is more conducive to the degradation of 2,4,5-trichlorophenol. However, when the degradation temperature is higher than 25 °C, the degradation efficiency of 2,4,5-trichlorophenol decreases significantly. This may be because with the increase of temperature, the reaction rates of both the electrocatalytic degradation reaction of 2,4,5-trichlorophenol and the oxygen evolution side reaction also increase. However, the oxygen evolution side reaction will inhibit the degradation reaction of 2,4,5-trichlorophenol, reducing the current efficiency of the degradation reaction, and thus the removal rate of 2,4,5-trichlorophenol decreases accordingly. Therefore, when the temperature of the degradation solution is 25 °C, the degradation efficiency of 2,4,5-trichlorophenol reaches a maximum of 98.4%. At the same time, most insoluble intermediates can be degraded at temperatures above 50 °C, which reduces the adsorption and aggregation of polymers and intermediates and slows down the passivation of the electrode. However, the experiment also found that there is a direct correlation between the increase in temperature and the increase in the corrosion degree of the graphite electrode. The particle electrode used as the electrocatalyst is more likely to dissolve. From the perspective of engineering applications, the cost of treating wastewater will increase with the increase in temperature. Therefore, from an economic point of view, 25 °C is the ideal electrolysis temperature. The selection of the electrocatalytic oxidation temperature depends on the corrosion resistance of the instrument and the stability of the electrode, because it was found in the experiment that when the temperature rises too high, the loss of the graphite electrode will be very large.

[0053] (5) Influence of cell voltage on the degradation of 2,4,5-trichlorophenol

[0054] The cell voltage is one of the prerequisites for electrochemical wastewater treatment. At the same electrolyte concentration, increasing the cell voltage is equivalent to increasing the current density. Under the conditions of a 2,4,5-trichlorophenol concentration of 150 mg / L in the simulated wastewater, an electrolyte concentration of 0.025 mol / L, a pH value of 3, an air velocity of 0.5 L / min, and a temperature of 25 °C, the influence of different cell voltages on the degradation of 2,4,5-trichlorophenol in the simulated wastewater was investigated. The results are shown in Figure 9 .

[0055] Figure 9It shows that when the cell voltage rises from 3.0 V to 6.0 V, the removal rate of 2,4,5-trichlorophenol increases from 71.4% to 97.1%. At this time, increasing the cell voltage is beneficial to improving the degradation effect. However, once the cell voltage reaches 9.0 V, the removal rate will decrease. This is because the degradation effect of the Cu-Ce@γ-Al2O3(111) particle electrode will gradually improve with the increase of the cell voltage. If the cell voltage is too high, the electrode may fail or produce adverse reaction products, which will also lead to excessive oxidation reaction on the electrode surface.

[0056] Although the increase in current density will accelerate the overall reaction rate, this effect depends on both the dissolution of the active components of the metal oxide and how the increase in current density affects the oxygen evolution side reaction. When the cell voltage is 9.0 V, after 90 min of reaction, the current intensity decreases from 0.32 A to 0.13 A, indicating that the particle electrode is deactivated quite severely. This is reflected in the removal rate, and with the extension of the reaction time, the removal rate shows a decreasing growth trend. Therefore, considering variables such as current efficiency and particle electrode life, the cell voltage is preferably 6.0 V.

[0057] (6) Influence of the initial concentration of 2,4,5-trichlorophenol on the electrolysis effect

[0058] Since the quality of phenolic wastewater discharged in actual industrial production varies greatly, from the perspective of engineering practice, it is particularly important to investigate the degradation effect of this system on 2,4,5-trichlorophenol wastewater with different concentrations. Therefore, under the conditions of controlling the concentration of the electrolyte in the simulated wastewater to be 0.025 mol / L, the pH value to be 3, the electrode plate spacing to be 20 mm, the air velocity to be 0.5 L / min, and the temperature to be 25 °C, the influence of the initial concentration of 2,4,5-trichlorophenol in the simulated wastewater on the degradation is investigated, and the results are shown in Figure 10 .

[0059] As Figure 10As shown in the figure, after electrolysis for 15 minutes, when the initial concentration of 2,4,5-trichlorophenol increased from 25 mg / L to 150 mg / L, the removal rate of 2,4,5-trichlorophenol decreased from 98.4% to 31.2%. This indicates that the higher the initial concentration of 2,4,5-trichlorophenol, the longer the time required for complete degradation. Therefore, the increase in the initial concentration inhibits the degradation of 2,4,5-trichlorophenol. This is because when other conditions are constant, the ability of the electrode to generate substances such as ·OH and active chlorine is limited. When the concentration of 2,4,5-trichlorophenol is relatively high, a lower proportion of 2,4,5-trichlorophenol is attacked by free radicals. In addition, the higher the concentration of 2,4,5-trichlorophenol, the more degradation intermediates are generated, which will inevitably compete with the parent compound for the reaction with free radicals. Therefore, the higher the concentration, the longer the degradation time required. At the same time, as the initial concentration of 2,4,5-trichlorophenol increases, more intermediate products are generated in the reaction, causing adsorption to contaminate the electrode and making the electrocatalytic oxidation process complex. In addition to 2,4,5-trichlorophenol, these intermediates will also compete for active substances. At this time, the removal rate of 2,4,5-trichlorophenol mainly depends on the yield of active substances. On the contrary, too low a concentration will lead to insufficient energy utilization. Therefore, considering comprehensively the removal effect of 2,4,5-trichlorophenol and energy consumption, on the premise of ensuring the efficient removal of 2,4,5-trichlorophenol, as many pollutants as possible should be treated, and 150 mg / L is selected as the optimal initial concentration of 2,4,5-trichlorophenol.

[0060] (7) Analysis of experimental results optimized by response surface method

[0061] Based on the above single-factor experiments, the Box-Behnken Design (BBD) method was used to optimize the degradation conditions of 2,4,5-trichlorophenol. The experimental design and results are shown in Table 2, and the variance regression analysis and significance test are shown in Table 3.

[0062] Table 2 shows the Box-Behnken combined experimental design and results

[0063]

[0064]

[0065]

[0066] Table 3 Regression equation

[0067]

[0068]

[0069] It can be seen from the analysis of variance in Table 3 that: for the model regression test, F = 29.8, P < 0.0001, and the difference is extremely significant. This indicates that the model has a good fitting degree, the experimental error is small, the influence is extremely significant, the difference between different treatments is significant, and the model is appropriate. From the significance test of the regression equation coefficients in Table 3, it can be known that the first-order terms A (P = 0.0001 < 0.05) are significant, B (P = 0.0026 < 0.05) are significant, C (P = 0.0189 < 0.05) are significant, and D (P < 0.0001) is extremely significant. The interaction term DE (P = 0.0016 < 0.05) is significant, and the interaction terms AB, AC, AD, AE, BC, BD, BE, CD, and CE are not significant. That is, only the interaction between the electrolytic cell voltage and the degradation temperature has a significant effect on the removal rate of 2,4,5-trichlorophenol (mol / L). The determination coefficient R 2 = 0.9597, which proves that the model fits well with the actual experiment and can be used as a theoretical prediction for the actual experiment. From the magnitudes of the F values in Table 3, it can be known that the order of the influence of each factor on the removal rate of 2,4,5-trichlorophenol is: electrolyte concentration > cell voltage > reaction temperature > electrode spacing > pH value.

Claims

1. A Cu-Ce@γ-Al2O3(111) particle electrode, characterized in that: The particle electrode is prepared by the following steps: Step 1: Dissolve triethylaluminum in ethylene glycol, add polyvinylpyrrolidone and EDTA, stir for 3 - 5 h to mix evenly, then transfer the obtained mixed solution into a hydrothermal autoclave with a polytetrafluoroethylene liner, carry out solvothermal reaction at 150 - 220 °C for 48 - 72 h, then centrifuge, wash with deionized water and dry to obtain γ-Al2O3 with exposed (111) crystal plane; Step 2: Mix an aqueous cerium nitrate solution, an aqueous copper nitrate solution, hydrochloric acid, and absolute ethanol evenly, then immerse the obtained solution into γ-Al2O3 with exposed (111) crystal plane, stir and mix well for 3 - 5 h, carry out vacuum filtration, dry, and then calcine at 550 - 600 °C for 4 - 6 h; Step 3: Repeat the operation steps of Step 2 two to three times for the product calcined in Step 2 to obtain the Cu-Ce@γ-Al2O3(111) particle electrode.

2. The Cu-Ce@γ-Al2O3(111) particle electrode according to claim 1, characterized in that: In Step 1, the mass ratio of the triethylaluminum, polyvinylpyrrolidone, and EDTA is 1:0.6 - 0.8:0.1 - 0.

2.

3. The Cu-Ce@γ-Al2O3(111) particle electrode according to claim 1 or 2, characterized in that: In Step 1, carry out solvothermal reaction at 170 - 200 °C for 48 - 72 h.

4. The Cu-Ce@γ-Al2O3(111) particle electrode according to claim 1 or 2, characterized in that: In Step 1, dry at 60 - 80 °C for 12 - 24 h.

5. The Cu-Ce@γ-Al2O3(111) particle electrode according to claim 1, characterized in that: In Step 2, the volume ratio of the aqueous cerium nitrate solution, the aqueous copper nitrate solution, hydrochloric acid, and absolute ethanol is 1:0.5 - 1:0.7 - 1:1, where the concentration of cerium nitrate in the aqueous cerium nitrate solution is 6 - 8 mmol / L, the concentration of copper nitrate in the aqueous copper nitrate solution is 0.5 - 1 mmol / L, and the concentration of hydrochloric acid is 0.5 - 1 mmol / L.

6. The Cu-Ce@γ-Al2O3(111) particle electrode according to claim 1, wherein: In Step 2, calcine at 550 °C for 4 h.

7. The Cu-Ce@γ-Al2O3(111) particle electrode according to claim 1 or 6, characterized in that: In Step 2, the heating rate of the calcination is 3 - 8 °C / min.

8. Use of the Cu-Ce@γ-Al2O3(111) particle electrode for electrochemically catalytically oxidizing and degrading 2,4,5-trichlorophenol wastewater as described in claim 1, characterized in that: Add 2,4,5-trichlorophenol wastewater into a three-dimensional electrode reactor, which includes an anode, a cathode, and the Cu-Ce@γ-Al2O3(111) particle electrode arranged between the two plates; add an electrolyte into the 2,4,5-trichlorophenol wastewater and mix well to make the concentration of the electrolyte in the 2,4,5-trichlorophenol wastewater 0.01 - 0.05 mol / L, then add hydrochloric acid to adjust the pH value to 2 - 6, and introduce air. Under the conditions of an electrode spacing of 15 - 25 mm, a cell voltage of 4 - 7 V, an air velocity of 0.5 - 0.7 L / min, and a temperature of 10 - 30 °C, carry out electrochemical catalytic oxidation to degrade 2,4,5-trichlorophenol.

9. Use of the Cu-Ce@γ-Al2O3(111) particle electrode for electrochemically catalytically oxidizing and degrading 2,4,5-trichlorophenol wastewater according to claim 8, characterized in that: The anode is a stainless steel plate, the cathode is a graphite plate, and the electrolyte is Na2SO4.

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