Rapid electrocatalytic oxidation sewage treatment system based on boron-doped diamond mesh electrode and boron-doped graphene mesh electrode

Abstract

The present invention discloses a rapid electrocatalytic oxidation sewage treatment system based on boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes. The system comprises: N composite electrodes, an electrolytic cell, and a power supply, where N is an integer greater than or equal to 1. The N composite electrodes are located within the electrolytic cell, and each composite electrode comprises a boron-doped diamond mesh electrode and a boron-doped graphene mesh electrode spaced apart. The boron-doped graphene mesh electrode serves as a cathode, and the boron-doped diamond mesh electrode serves as an anode. The anode and cathode are each connected to the power supply. When using only one composite electrode, the system degrades 30 mg / L of simulated sewage methyl orange in a fading time of 30 seconds, at a degradation rate of 6.7 mg / s. This system provides rapid, environmentally friendly, and low-consumption sewage treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic sewage treatment, and in particular relates to a rapid electrocatalytic oxidation sewage treatment system based on boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes. Background Art

[0002] Water resource security in my country is increasingly becoming a significant factor constraining economic growth. Water pollution is a major concern. Industrial wastewater contains numerous pollutants. Direct discharge can cause severe water pollution, endangering human health and impacting both industrial production and social life. Traditional wastewater treatment methods, including physical adsorption and chemical oxidation, often consume large quantities of chemicals and are complex, challenging, and time-consuming. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a rapid electrocatalytic oxidation sewage treatment system based on boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes. This rapid electrocatalytic oxidation sewage treatment system utilizes the superior physical and chemical stability of boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes, and also combines rapid electrochemical oxidation technology. It is more efficient, more environmentally friendly, and consumes less materials than traditional methods.

[0004] The purpose of the present invention is achieved through the following technical solutions.

[0005] A rapid electrocatalytic oxidation sewage treatment system based on boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes comprises: N composite electrodes, an electrolytic cell and a power supply, wherein N is an integer greater than or equal to 1, the N composite electrodes are located in the electrolytic cell, and each composite electrode comprises: a boron-doped diamond mesh electrode and a boron-doped graphene mesh electrode arranged at intervals, the boron-doped graphene mesh electrode serving as a cathode, and the boron-doped diamond mesh electrode serving as an anode, and the anode and cathode are respectively connected to the power supply.

[0006] In the above technical solution, the voltage applied by the power supply to each composite electrode is 1 to 10V.

[0007] In the above technical solution, the power supply is a DC power supply.

[0008] In the above technical solution, N=1-10.

[0009] In the above technical solution, when N>1, the N composite electrodes are arranged at intervals and the boron-doped diamond mesh electrodes and the boron-doped graphene mesh electrodes are staggered, the distance between each boron-doped diamond mesh electrode and its adjacent boron-doped graphene mesh electrode is 1 to 3 cm, all the boron-doped diamond mesh electrodes of the N composite electrodes are connected in parallel / series and then connected to the power supply, and all the boron-doped graphene mesh electrodes of the N composite electrodes are connected in parallel / series and then connected to the power supply.

[0010] In the above technical solution, the boron-doped diamond mesh electrode is a first substrate and a boron-doped diamond film grown on the first substrate, and the boron-doped graphene mesh electrode is a second substrate and a boron-doped graphene film grown on the second substrate. The thickness of the boron-doped diamond film is 3 to 16 μm, and the thickness of the boron-doped graphene film is 1 to 3 nm.

[0011] In the above technical solution, the boron-doped diamond mesh electrode and the boron-doped graphene mesh electrode are both mesh-shaped, the first substrate is a titanium mesh, the thickness of the first substrate is 1 to 2 mm, and the mesh size of the first substrate is 10 to 300 meshes; the second substrate is a titanium mesh, the thickness of the second substrate is 1 to 2 mm, and the mesh size of the second substrate is 10 to 300 meshes.

[0012] In the above technical solution, the electrolytic cell is tubular, and N composite electrodes are fixed in the electrolytic cell along the length direction of the tube. One end of the electrolytic cell is a water inlet, and the other end is a water outlet, so that sewage enters from the water inlet, passes through the mesh of the N composite electrodes, and is discharged from the water outlet.

[0013] In the above technical solution, the first substrate is a circle with a diameter of 5 to 60 mm, the second substrate is a circle with a diameter of 5 to 60 mm, and the inner diameter of the electrolytic cell is compatible with the first substrate and the second substrate.

[0014] In the above technical solution, a pump is also included for inputting sewage into the electrolytic cell.

[0015] In the above technical solution, the method for preparing the boron-doped diamond mesh electrode comprises the following steps:

[0016] 1) ultrasonically treating a first substrate in a diamond micro-nano powder suspension for at least 60 minutes, washing the substrate with ultrapure water, anhydrous ethanol, and ultrapure water, and drying the substrate to obtain a nucleated substrate, wherein the diamond micro-nano powder suspension is a mixture of diamond micro-nano powder and a solvent, and the concentration of the diamond micro-nano powder in the diamond micro-nano powder suspension is 1 to 3 mg / mL;

[0017] In the step 1), the solvent is a mixture of acetone and anhydrous ethanol, and the ratio of acetone to anhydrous ethanol in the solvent is 1:(1-1.2) by volume.

[0018] In the step 1), the cleaning is performed by placing the product in a cleaning liquid and ultrasonically applying the product for 5 to 15 minutes. The cleaning liquid is the ultrapure water, anhydrous ethanol or ultrapure water.

[0019] In the step 1), the drying is performed by baking with an infrared baking lamp.

[0020] 2) Using an electron-assisted hot-wire chemical vapor deposition method, the nucleated substrate is used as a carrier to grow a boron-doped diamond film to obtain a boron-doped diamond mesh electrode.

[0021] In the above technical solution, the preparation method of the boron-doped graphene mesh electrode includes the following steps: using an electron-assisted hot-wire chemical vapor deposition method with a second substrate as a carrier, growing a boron-doped graphene film on the second substrate, and obtaining a boron-doped graphene mesh electrode.

[0022] In the above technical solution, the steps of the electron-assisted hot-wire chemical vapor deposition method are:

[0023] ① Carbonization stage: The carrier is placed in a reaction chamber, vacuumed, and hydrogen and methane are introduced into the reaction chamber. When the pressure in the reaction chamber reaches 2000-3000 Pa, the filament current is adjusted to 100-120 A while hydrogen and methane are continuously introduced into the reaction chamber. When the pressure in the reaction chamber reaches 5000-5200 Pa, the pressure is maintained for another 30 minutes.

[0024] In the above-mentioned step ①, the flow ratio of hydrogen to methane in the carbonization stage is 300:(18-20).

[0025] ② Growth stage: While maintaining the pressure in the reaction chamber at 5000-5200 Pa, a boron source is introduced into the reaction chamber, a bias voltage is applied to the carrier, and the carrier temperature is kept at T°C for t min, wherein the current of the bias power supply is a A and the voltage of the bias power supply is v V;

[0026] When the electron-assisted hot-wire chemical vapor deposition method is used to grow a boron-doped diamond film on the nucleated substrate as a carrier, T=800-900°C, t=60-4800, a=5-10, v=170-190;

[0027] When the electron-assisted hot-wire chemical vapor deposition method is used to grow a boron-doped graphene film on the second substrate using the second substrate as a carrier, T=1100-1200° C., t=5-60, a=4, and v=35.

[0028] In the step ②, the boron source is introduced into the reaction chamber via a carrier gas during the growth stage. The method for introducing the boron source into the reaction chamber via the carrier gas is as follows: the carrier gas is input into the mixed liquid and then bubbled out from the mixed liquid, and the bubbled gas is input into the reaction chamber, wherein the mixed liquid is a mixture of trimethyl borate and anhydrous ethanol, and the ratio of trimethyl borate to anhydrous ethanol is 3:(1 to 1.2) by volume.

[0029] In ②, during the growth stage, the hydrogen is divided into two parts: one directly introduced into the reaction chamber and the other used as the carrier gas. The ratio of the hydrogen directly introduced into the reaction chamber to the hydrogen used as the carrier gas is X by volume, and the ratio of the carrier gas to methane is Y by volume.

[0030] When the nucleated substrate is used as a carrier to grow a boron-doped diamond film by an electron-assisted hot-wire chemical vapor deposition method, X=300:(0.001-50), Y=(0.001-50):6;

[0031] When the electron-assisted hot-filament chemical vapor deposition method is used to take the second substrate as a carrier and a boron-doped graphene film is grown on the second substrate, X=40:(0.001-50), Y=(0.001-50):10.

[0032] The composite electrode in the above-mentioned rapid electrocatalytic oxidation sewage treatment system.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention can degrade and discolor high COD organic wastewater by applying a 5V voltage to the composite electrode;

[0035] 2. Compared with the traditional electrocatalytic degradation water treatment system, the rapid electrocatalytic oxidation sewage treatment system uses a boron-doped diamond mesh electrode as the anode and a boron-doped graphene mesh electrode as the cathode. When only one composite electrode is used, the fading time of 30 mg / L methyl orange simulated sewage is 30 seconds, and the degradation rate is 6.7 mg / s, which can treat sewage quickly, greenly and with low consumption.

[0036] 3. Rapid electrocatalytic oxidation wastewater treatment systems can be tubular. The diameter of the boron-doped diamond mesh electrode / boron-doped graphene mesh electrode can reach 60mm, significantly increasing the contact area with the wastewater and further improving treatment efficiency. The composite electrode can be used in conjunction with sewage drain pipes and can be installed using a plug-in installation method, facilitating removal and replacement of the composite electrode.

[0037] 4. Boron-doped diamond mesh electrodes have better physical and chemical stability, ultra-high hardness and wear resistance, and excellent temperature stability. They can be used in relatively harsh environments. In addition, a large number of hydroxyl free radicals are generated on the surface, which has anti-pollution and self-cleaning functions. They have a long service life and do not need to be replaced frequently.

[0038] 5. The boron-doped graphene mesh electrode obtained by electron-assisted hot-filament chemical vapor deposition has good quality and strong bonding with the second substrate, and pollutants adsorbed on its surface will be quickly desorbed and degraded. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the structure of the rapid electrocatalytic oxidation sewage treatment system in Example 10;

[0040] Figure 2 This is a photo of a boron-doped diamond mesh electrode;

[0041] Figure 3 This is the SEM of the boron-doped diamond mesh electrode;

[0042] Figure 4 This is a photo of a boron-doped graphene mesh electrode;

[0043] Figure 5 This is the SEM of the boron-doped graphene mesh electrode;

[0044] Figure 6 These are photos of the simulated wastewater after degradation in Examples 5 to 9;

[0045] Figure 7 The UV-visible spectra of the simulated wastewater after degradation in Examples 5 to 9 were measured using a UV-3600 UV-visible-near-infrared spectrophotometer;

[0046] Figure 8 Graph showing the relationship between the voltage applied to the composite electrode and the absorbance after degradation of the simulated sewage in Examples 5 to 9. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further described below with reference to specific embodiments.

[0048] The electron-assisted hot-filament chemical vapor deposition method uses an electron-assisted hot-filament chemical vapor deposition device (HFCVD) produced by Shenyang Scientific Instrument Co., Ltd., Chinese Academy of Sciences (the volume of the reaction chamber is 120 L).

[0049] Example 1

[0050] A rapid electrocatalytic oxidation sewage treatment system based on boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes comprises: N composite electrodes, an electrolytic cell and a power supply, wherein the power supply is a DC power supply, and the voltage applied by the power supply to each composite electrode is 1 to 10V, where N=1 to 10. The N composite electrodes are located in the electrolytic cell, and each composite electrode comprises: a boron-doped diamond mesh electrode and a boron-doped graphene mesh electrode arranged at intervals.

[0051] When N>1, the N composite electrodes are spaced apart and the boron-doped diamond mesh electrodes and the boron-doped graphene mesh electrodes are staggered. All the boron-doped diamond mesh electrodes of the N composite electrodes can be connected in parallel or in series before being connected to the power supply as anodes, and all the boron-doped graphene mesh electrodes of the N composite electrodes can be connected in parallel or in series before being connected to the power supply as cathodes. When N=1, the boron-doped diamond mesh electrode is directly connected to the power supply as the anode, and the boron-doped graphene mesh electrode is directly connected to the power supply as the cathode.

[0052] The distance between each boron-doped diamond mesh electrode and its adjacent boron-doped graphene mesh electrode is 2 cm, so that the sewage can fully contact the composite electrode.

[0053] The boron-doped diamond mesh electrode is a first substrate and a boron-doped diamond film grown on the first substrate, and the boron-doped graphene mesh electrode is a second substrate and a boron-doped graphene film grown on the second substrate.

[0054] The method of using the above-mentioned rapid electrocatalytic oxidation sewage treatment system is: turning on the power supply, adjusting the voltage of the power supply, and allowing the sewage to pass through the boron-doped diamond mesh electrode and the boron-doped graphene mesh electrode.

[0055] Example 2

[0056] Based on Example 1, a method for preparing a boron-doped diamond mesh electrode comprises the following steps:

[0057] 1) ultrasonically treating the first substrate in ultrapure water, anhydrous ethanol, and ultrapure water for 15 minutes each, ultrasonically treating the first substrate in a diamond micro-nano powder suspension for 80 minutes, ultrasonically treating the first substrate in ultrapure water, anhydrous ethanol, and ultrapure water for 10 minutes each, and baking the substrate with an infrared baking lamp for 5 minutes to obtain a nucleated substrate, wherein the diamond micro-nano powder suspension is a mixture of diamond micro-nano powder (purchased from Shanghai Aladdin Technology Co., Ltd., with a particle size of 50 microns) and a solvent, the concentration of the diamond micro-nano powder in the diamond micro-nano powder suspension is 3 mg / mL, and the solvent is a mixture of acetone and anhydrous ethanol, and the ratio of acetone to anhydrous ethanol in the solvent is 1:1 by volume;

[0058] 2) Using electron-assisted hot-wire chemical vapor deposition method, the nucleated substrate is used as a carrier to grow a boron-doped diamond film to obtain a boron-doped diamond mesh electrode, such as Figure 2 and Figure 3 As shown in Figure 2, the thickness of the boron-doped diamond film is 16 μm.

[0059] The steps of the above-mentioned electron-assisted hot-wire chemical vapor deposition method are as follows:

[0060] ① Carbonization stage: The nucleated substrate serving as a carrier is placed on the sample stage in the reaction chamber so that the carrier and the sample stage are in contact. The reaction chamber is closed, and the water circulation, flow display, vacuum gauge, mechanical pump and alarm are turned on in sequence. The mechanical pump starts to evacuate the chamber. When the pressure in the reaction chamber reaches 17 Pa, hydrogen is introduced to remove the residual gas and complete the gas washing. When the pressure in the reaction chamber reaches 15 Pa, hydrogen and methane (purity 99.999%) are continuously introduced into the reaction chamber. The filament power supply and bias preheating are turned on. When the pressure in the reaction chamber reaches 2000 Pa, the filament current is adjusted to 115 A and hydrogen and methane are continuously introduced into the reaction chamber. When the pressure in the reaction chamber reaches 5200 Pa, the pressure is maintained for another 30 minutes. The flow rate (volume, the same below) ratio of hydrogen and methane in the carbonization stage is 300:18.

[0061] ② Growth stage: Under the condition of maintaining a pressure of 5200 Pa in the reaction chamber (continuously introducing hydrogen and methane), the hydrogen is divided into two parts: directly introduced into the reaction chamber and used as a carrier gas. The ratio of hydrogen directly introduced into the reaction chamber and hydrogen used as a carrier gas is 300:36 by volume. The ratio of carrier gas to methane is 36:6 ​​by volume. The carrier gas is input into the mixture of trimethyl borate and anhydrous ethanol and then bubbled out. Gas is input into the reaction chamber to introduce a boron source into the reaction chamber, bias the carrier and simultaneously set the temperature of the carrier to 900°C for 180 minutes, wherein the current of the applied bias power supply is 7A, the voltage of the applied bias power supply is 180V (the applied bias power supply is a DC power supply, the bias refers to the bias between the filament and the sample stage, the sample stage is the positive electrode, and the filament is the negative electrode). The ratio of trimethyl borate to anhydrous ethanol in the mixed liquid is 3:1 by volume.

[0062] Example 3

[0063] On the basis of Example 2, a method for preparing a boron-doped graphene mesh electrode comprises the following steps: polishing a second substrate, ultrasonically treating the second substrate in ultrapure water, anhydrous ethanol, and ultrapure water for 15 minutes each, baking the second substrate with a baking lamp for 5 minutes, and using an electron-assisted hot-wire chemical vapor deposition method to grow a boron-doped graphene film on the second substrate using the second substrate as a carrier to obtain a boron-doped graphene mesh electrode, such as Figure 4 and Figure 5 As shown in Figure 2, the thickness of the boron-doped graphene film is 2 nm.

[0064] The steps of the electron-assisted hot-filament chemical vapor deposition method are:

[0065] ① Carbonization stage: Place the second substrate as a carrier on the sample stage in the reaction chamber so that the carrier and the sample stage are in contact. Close the reaction chamber, turn on the water circulation, flow display, vacuum gauge, mechanical pump and alarm in sequence, and the mechanical pump starts to evacuate. When the pressure in the reaction chamber reaches 17 Pa, hydrogen is introduced to remove the residual gas to complete the gas washing. When the pressure in the reaction chamber reaches 15 Pa, hydrogen and methane (purity 99.999%) are continuously introduced into the reaction chamber. Turn on the filament power supply and bias preheating. When the pressure in the reaction chamber reaches 2000 Pa, adjust the filament current to 115 A and continue to introduce hydrogen and methane into the reaction chamber. When the pressure in the reaction chamber reaches 5200 Pa, maintain it for another 30 minutes. The flow ratio of hydrogen to methane in the carbonization stage is 300:18.

[0066] ② Growth stage: Under the condition of maintaining a pressure of 5200 Pa in the reaction chamber (continuously introducing hydrogen and methane), the hydrogen is divided into two parts: directly introduced into the reaction chamber and used as a carrier gas, and the ratio of hydrogen directly introduced into the reaction chamber and hydrogen used as a carrier gas is 40:36 by volume, and the ratio of carrier gas to methane is 36:10 by volume. The carrier gas is input into a mixture of trimethyl borate and anhydrous ethanol and then bubbled out, and the bubbled gas is input into the reaction chamber for introducing a boron source into the reaction chamber. A bias is applied to the carrier and the temperature of the carrier is simultaneously set to 1100° C. for 15 min, wherein the current of the bias power supply is 4 A, and the voltage of the bias power supply is 35 V (the bias power supply is a DC power supply, and the bias refers to the bias between the filament and the sample stage, the sample stage is the positive electrode, and the filament is the negative electrode). The ratio of trimethyl borate and anhydrous ethanol in the mixed liquid is 3:1 by volume.

[0067] Example 4

[0068] Based on Example 3, N = 1, the thickness of the first substrate is 1 mm, and the thickness of the second substrate is 1 mm. The boron-doped diamond mesh electrode and the boron-doped graphene mesh electrode are both mesh-shaped. The first substrate is a titanium mesh with a mesh size of 215 mesh; the second substrate is a titanium mesh with a mesh size of 215 mesh. The first substrate is circular with a diameter of 60 mm, and the second substrate is circular with a diameter of 60 mm.

[0069] Example 5

[0070] The rapid electrocatalytic oxidation sewage treatment system in Example 4 was tested:

[0071] Prepare simulated sewage: prepare a 1000ml volumetric flask, use an analytical balance to weigh 30mg of methyl orange powder, and put it into the prepared volumetric flask; then use an analytical balance to weigh 5.844g of NaCl, put it into the prepared volumetric flask, add an appropriate amount of ultrapure water, gently shake the volumetric flask to fully dissolve it, and then add ultrapure water to the volumetric flask. When the liquid level is 1 to 2cm below the 1000ml scale line of the volumetric bottleneck, use a rubber-tipped dropper to add ultrapure water until the liquid level is tangent to the 1000ml scale line. The simulated sewage preparation is completed.

[0072] Place 150 mL of simulated sewage in the electrolytic cell.

[0073] The electrolytic cell containing the simulated sewage was placed on a magnetic stirrer, and a magnetic rotor was placed in the electrolytic cell.

[0074] Fix the composite electrode with an electrode clamp, turn on the magnetic stirrer, adjust the speed to 400 rpm, and adjust the height of the electrode clamp so that the composite electrode can fully contact and react with the simulated sewage. Turn on the power switch and adjust the power supply to apply a voltage of 5V to the composite electrode. Start timing for 30 seconds. You can visually observe that the color of the simulated sewage in the electrolytic cell changes from dark to light until it completely fades. After the timing is over, turn off the power switch and the magnetic stirrer, and take out the electrode clamp.

[0075] To accurately measure the treatment effect, a 10ml sample was taken from the electrolytic cell using a rubber-tipped burette for absorbance measurement. Calculations show that the simulated wastewater discoloration rate reached 76.28% when a 5V voltage was applied to the composite electrode for 30 seconds.

[0076] Example 6

[0077] This embodiment is basically the same as Embodiment 5, except that “turn on the power switch and adjust the power supply to apply a voltage of 5V to the composite electrode” is replaced by “turn on the power switch and adjust the power supply to apply a voltage of 4V to the composite electrode”.

[0078] Example 7

[0079] This embodiment is basically the same as Embodiment 5, except that “turn on the power switch and adjust the power supply to apply a voltage of 5V to the composite electrode” is replaced by “turn on the power switch and adjust the power supply to apply a voltage of 3V to the composite electrode”.

[0080] Example 8

[0081] This embodiment is basically the same as Embodiment 5, except that “turn on the power switch and adjust the power supply to apply a voltage of 5V to the composite electrode” is replaced by “turn on the power switch and adjust the power supply to apply a voltage of 2V to the composite electrode”.

[0082] Example 9

[0083] This embodiment is basically the same as Embodiment 5, except that “turn on the power switch and adjust the power supply to apply a voltage of 5V to the composite electrode” is replaced by “turn on the power switch and adjust the power supply to apply a voltage of 0V to the composite electrode”.

[0084] The photos of the treated simulated sewage obtained in Examples 5 to 9 are as follows: Figure 6 As shown in the figure (from right to left are Example 5, Example 6, Example 7, Example 8 and Example 9), the treated simulated sewage obtained in Examples 5 to 9 was tested for UV-visible spectra using a UV-3600 ultraviolet-visible-near-infrared spectrophotometer, as shown in FIG. Figure 7 shown.

[0085] Calculation formula: Fading rate = (absorbance of simulated sewage before degradation - absorbance of simulated sewage after degradation) × 100% / absorbance before simulated sewage degradation.

[0086] It is known from experiments that the voltage applied to the composite electrode is inversely proportional to the absorbance, such as Figure 8 shown.

[0087] Tests showed that when the applied voltage was 5V and the decomposition time was 30 seconds, the fading rate reached (1.5082-0.3577)×100% / 1.5082=76.28%. When the decomposition time was 60 seconds, the fading rate reached (1.5082-0.1328)×100% / 1.5082=91.19%. When the decomposition time was 120 seconds, the fading rate reached (1.5082-0.0636)×100% / 1.5082=95.78%.

[0088] Example 10

[0089] like Figure 1 As shown, a rapid electrocatalytic oxidation sewage treatment system based on boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes is basically the same as Example 4, except that N = 10. In addition, based on Example 4, the electrolytic cell is tubular with an inner diameter of 60 mm. N composite electrodes are fixedly installed in the electrolytic cell along the length of the tubular electrolytic cell. One end of the electrolytic cell is a water inlet, and the other end is a water outlet. A pump (peristaltic pump) allows sewage to enter through the water inlet and be discharged from the water outlet after passing through the N composite electrodes. The pump can adjust the flow rate of the sewage entering the water inlet to maintain a uniform flow rate. The sewage flows through the mesh of the boron-doped diamond mesh electrode and the boron-doped graphene mesh electrode into the next pair of boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes until it passes through the last composite electrode and is discharged from the water outlet.

[0090] The diameters of the boron-doped diamond mesh electrodes and the boron-doped graphene mesh electrodes match the inner diameter of the electrolytic cell. By designing the electrolytic cell into a tubular shape, it simulates a sewage drain pipe, allowing the composite electrode to be used in conjunction with the pipe. Furthermore, the composite electrode can be installed using a plug-in design, facilitating its removal and replacement. The rapid electrocatalytic oxidation wastewater treatment system allows for intuitive observation of brightly colored, high-COD wastewater entering the inlet and its color changing from dark to light or completely fading as it exits the outlet.

[0091] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by other skilled in the art without expending creative labor falls within the scope of protection of the present invention.

Claims

1. A rapid electrocatalytic oxidation sewage treatment system based on boron-doped diamond mesh electrodes and boron-doped graphene mesh electrodes, characterized in that: include: N composite electrodes, an electrolytic cell and a power supply, N is an integer greater than or equal to 1, the N composite electrodes are located in the electrolytic cell, each of the composite electrodes includes: a boron-doped diamond mesh electrode and a boron-doped graphene mesh electrode arranged at intervals, the boron-doped graphene mesh electrode serves as a cathode, the boron-doped diamond mesh electrode serves as an anode, the anode and cathode are respectively connected to the power supply, the boron-doped diamond mesh electrode and the boron-doped graphene mesh electrode are both mesh-shaped, the boron-doped diamond mesh electrode is a first substrate and a boron-doped diamond film grown on the first substrate, the boron-doped graphene mesh electrode is a second substrate and a boron-doped graphene film grown on the second substrate, the first substrate is a titanium mesh, and the second substrate is a titanium mesh.

2. The rapid electrocatalytic oxidation sewage treatment system according to claim 1, characterized in that: The voltage applied by the power supply to each composite electrode is 1 to 10V.

3. The rapid electrocatalytic oxidation sewage treatment system according to claim 2, characterized in that: N=1~10. When N>1, the N composite electrodes are arranged at intervals and the boron-doped diamond mesh electrodes and the boron-doped graphene mesh electrodes are staggered. The distance between each boron-doped diamond mesh electrode and its adjacent boron-doped graphene mesh electrode is 1~3 cm. All the boron-doped diamond mesh electrodes of the N composite electrodes are connected in parallel / series and then connected to the power supply. All the boron-doped graphene mesh electrodes of the N composite electrodes are connected in parallel / series and then connected to the power supply.

4. The rapid electrocatalytic oxidation sewage treatment system according to claim 3, characterized in that: The power supply is a direct current power supply, the thickness of the boron-doped diamond film is 3 to 16 μm, and the thickness of the boron-doped graphene film is 1 to 3 nm.

5. The rapid electrocatalytic oxidation sewage treatment system according to claim 4, characterized in that: The thickness of the first substrate is 1-2 mm, and the mesh size of the first substrate is 10-300 meshes; the thickness of the second substrate is 1-2 mm, and the mesh size of the second substrate is 10-300 meshes.

6. The rapid electrocatalytic oxidation sewage treatment system according to claim 5, characterized in that: The electrolytic cell is tubular, and N composite electrodes are fixedly installed in the electrolytic cell along the length direction of the tube. One end of the electrolytic cell is a water inlet, and the other end is a water outlet, so that sewage enters from the water inlet and passes through the mesh of the N composite electrodes and is discharged from the water outlet; the first substrate is circular with a diameter of 5 to 60 mm, the second substrate is circular with a diameter of 5 to 60 mm, and the inner diameter of the electrolytic cell is compatible with the first substrate and the second substrate.

7. The rapid electrocatalytic oxidation sewage treatment system according to claim 1 or 2, characterized in that: The preparation method of the boron-doped diamond mesh electrode comprises the following steps: 1) ultrasonically treating a first substrate in a diamond micro-nano powder suspension for at least 60 minutes, washing the substrate with ultrapure water, anhydrous ethanol, and ultrapure water, and drying the substrate to obtain a nucleated substrate, wherein the diamond micro-nano powder suspension is a mixture of diamond micro-nano powder and a solvent, and the concentration of the diamond micro-nano powder in the diamond micro-nano powder suspension is 1 to 3 mg / mL; 2) using the nucleated substrate as a carrier to grow a boron-doped diamond film using an electron-assisted hot-wire chemical vapor deposition method to obtain a boron-doped diamond mesh electrode; The method for preparing the boron-doped graphene mesh electrode comprises the following steps: using an electron-assisted hot-wire chemical vapor deposition method with a second substrate as a carrier, growing a boron-doped graphene film on the second substrate, and obtaining the boron-doped graphene mesh electrode.

8. The rapid electrocatalytic oxidation sewage treatment system according to claim 7, characterized in that: In the step 1), the solvent is a mixture of acetone and anhydrous ethanol, and the ratio of acetone to anhydrous ethanol in the solvent is 1:(1-1.2) by volume; In the step 1), the cleaning is performed by ultrasonicating the cleaning liquid for 5 to 15 minutes, and the cleaning liquid is the ultrapure water, anhydrous ethanol or ultrapure water; In the step 1), the drying is performed by baking with an infrared baking lamp.

9. The rapid electrocatalytic oxidation sewage treatment system according to claim 8, characterized in that: The steps of the electron-assisted hot-wire chemical vapor deposition method are as follows: ① Carbonization stage: The carrier is placed in a reaction chamber, vacuumed, and hydrogen and methane are introduced into the reaction chamber. When the pressure in the reaction chamber reaches 2000-3000 Pa, the filament current is adjusted to 100-120 A while hydrogen and methane are continuously introduced into the reaction chamber. When the pressure in the reaction chamber reaches 5000-5200 Pa, the pressure is maintained for another 30 minutes. ② Growth stage: While maintaining the pressure in the reaction chamber at 5000-5200 Pa, a boron source is introduced into the reaction chamber, a bias voltage is applied to the carrier, and the carrier temperature is kept at T°C for t min, wherein the current of the bias power supply is a A and the voltage of the bias power supply is v V; When the electron-assisted hot-wire chemical vapor deposition method is used to grow a boron-doped diamond film on the nucleated substrate as a carrier, T=800-900°C, t=60-4800, a=5-10, v=170-190; When the electron-assisted hot-wire chemical vapor deposition method is used to grow a boron-doped graphene film on the second substrate using the second substrate as a carrier, T=1100-1200° C., t=5-60, a=4, and v=35.

10. The rapid electrocatalytic oxidation sewage treatment system according to claim 9, characterized in that: In the above-mentioned step ①, the flow ratio of hydrogen to methane in the carbonization stage is 300:(18-20); In said step ②, during the growth stage, the boron source is introduced into the reaction chamber via a carrier gas, and the method of introducing the boron source into the reaction chamber via the carrier gas is as follows: the carrier gas is input into the mixed liquid and then bubbling out from the mixed liquid, and the gas discharged by bubbling is input into the reaction chamber, wherein the mixed liquid is a mixture of trimethyl borate and anhydrous ethanol, and the ratio of trimethyl borate to anhydrous ethanol is 3:(1-1.2) by volume; In ②, during the growth stage, the hydrogen is divided into two parts: one directly introduced into the reaction chamber and the other used as the carrier gas. The ratio of the hydrogen directly introduced into the reaction chamber to the hydrogen used as the carrier gas is X by volume, and the ratio of the carrier gas to methane is Y by volume. When an electron-assisted hot-wire chemical vapor deposition method is used to grow a boron-doped diamond film using the nucleated substrate as a carrier, X=300:(0.001~50), Y=(0.001~50):6; when an electron-assisted hot-wire chemical vapor deposition method is used to grow a boron-doped graphene film on the second substrate using the second substrate as a carrier, X=40:(0.001~50), Y=(0.001~50):10.

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