A composite electrolyte fluorescent wastewater treatment process based on a BDD electrode

Abstract

The present application relates to a kind of composite electrolyte fluorescent wastewater treatment processes based on BDD electrode, which includes the following steps: (1) slag removal filtration is carried out to fluorescent wastewater;(2) a certain quality of anhydrous sodium sulfate and sodium chloride is added to the filtered fluorescent wastewater, and it is completely dissolved after stirring;(3) the fluorescent wastewater after dissolving electrolyte is pumped into electrochemical reactor;(4) direct current power supply is started;(5) electrochemical reactor is connected with activated carbon gas adsorption device, and the gas generated in electrolysis process is adsorbed by activated carbon.The present application uses BDD electrode and composite electrolyte to act together, and SO4 2‑ And Cl ‑ Form double oxygen system in composite electrolyte, which can reduce energy consumption and prolong electrode life, has the advantages of simple operation, high efficiency, environmental protection, low cost and the like, and the COD value of wastewater after treatment can reach 0-46mg / L, which meets the first level standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard", especially when the molar ratio of anhydrous sodium sulfate and sodium chloride is 2:1 and the current density is 50mA / cm², the effect is remarkable.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology in the fluorescent flaw detection industry, and particularly to a composite electrolyte fluorescent wastewater treatment process based on BDD electrodes. Background Technology

[0002] Precision fluorescent flaw detection technology is a key method for detecting surface defects in core components in aerospace, rail transportation, automobile manufacturing, and high-end equipment industries. It achieves precise identification of microscopic defects through the penetration and imaging of fluorescent penetrants at the surface defects, becoming an indispensable process for ensuring the manufacturing precision of core components. However, in the cleaning process for residual fluorescent penetrants on component surfaces, multiple rounds of cleaning using high-pressure spraying combined with specialized cleaning agents are required to ensure subsequent testing accuracy and surface cleanliness. This generates a large amount of fluorescent wastewater, with fluorescent substances as the core pollutant, and its discharge is increasing year by year with the development of high-end manufacturing.

[0003] Fluorescent wastewater is characterized by high color intensity, high chemical oxygen demand (COD), and high toxicity. The fluorescent dye molecules contained in the water have a stable conjugated double bond structure. In order to improve the permeability, they often form a stable complexation system with auxiliaries such as organic amines, esters, and alcohols. This results in a generally high COD concentration in the wastewater and extremely strong chemical stability, making it difficult for conventional treatment technologies to achieve effective degradation.

[0004] Current methods for treating fluorescent wastewater mainly rely on biochemical processes, combined with pretreatment methods such as coagulation sedimentation and adsorption. These methods suffer from drawbacks including complex processes, long treatment times, large sludge production, poor tolerance to highly toxic wastewater, inability to completely mineralize pollutants, and a tendency to generate secondary pollution, resulting in unsatisfactory treatment outcomes. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a composite electrolyte fluorescent wastewater treatment process based on BDD electrodes, along with process parameters that demonstrate excellent treatment effects on fluorescent wastewater. This process offers advantages such as simple operation, high efficiency, no secondary pollution, reduced energy consumption, and extended electrode lifespan.

[0006] To achieve the above objectives, the present invention provides a fluorescent wastewater treatment process, comprising the following steps: (1) The fluorescent wastewater is filtered to remove slag to ensure that no solid particles damage the electrodes.

[0007] (2) Add a certain amount of anhydrous sodium sulfate and sodium chloride to the filtered fluorescent wastewater and stir until they are completely dissolved.

[0008] (3) Pump the fluorescent wastewater after dissolving the electrolyte into the electrochemical reactor and set the reaction conditions according to parameters such as electrode-to-water ratio and current density.

[0009] (4) Turn on the DC power supply and take samples of the wastewater for analysis at regular intervals. During the electrolysis process, the BDD anode produces oxidizing substances that participate in the reaction, efficiently degrading pollutants in the fluorescent wastewater, so that the effluent meets the Class I standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard".

[0010] (5) The electrochemical reactor is connected to the activated carbon gas adsorption device. The gas generated during the electrolysis process is adsorbed by the activated carbon, and the discharged gas meets the secondary standard in the "Integrated Emission Standard of Air Pollutants" (GB 16297-1996).

[0011] A composite electrolyte fluorescent wastewater treatment process based on BDD electrodes, characterized by comprising the following steps: (1) Use 10µm qualitative filter paper to remove slag from fluorescent wastewater; (2) Add a certain mass of anhydrous sodium sulfate and sodium chloride to the filtered fluorescent wastewater and stir until completely dissolved; (3) The dissolved fluorescent wastewater was pumped into the electrochemical reactor, with a total of 500 mL of wastewater pumped in. The effective electrode area of ​​the reactor was 100-150 cm². 2 ; (4) Set the power supply current to 3.6-6A, turn on the DC power supply, and periodically sample and analyze the wastewater; (5) The electrochemical reactor is directly connected to the activated carbon gas adsorption device, and the gas generated during the electrolysis process is adsorbed by the activated carbon.

[0012] In step (1), the slag removal filtration is carried out by laying qualitative filter paper in a Buchner funnel, wetting the filter paper with deionized water and fixing it under vacuum, and then performing vacuum filtration.

[0013] In step (2), the total amount of anhydrous sodium sulfate and sodium chloride added is 0.05 mol / L, and the molar ratio of the two is 1:2-2:1.

[0014] In step (3), the anode of the electrochemical reactor is a BDD electrode, the cathode is a Ti electrode, the pH of the wastewater is adjusted to 6-8, the reaction is carried out at 20-30℃ and 100kPa, and the current density is set to 30-50mA / cm². 2 The corresponding current is 3.6-6A.

[0015] The sampling volume in step (4) is 3-4 mL.

[0016] Furthermore, in step (1), the slag removal filtration is carried out by laying qualitative filter paper in a Buchner funnel, wetting the filter paper with deionized water and fixing it under vacuum.

[0017] Furthermore, in step (2), the amount of anhydrous sodium sulfate and sodium chloride added is calculated in a molar ratio of 1:2 to 2:1.

[0018] Furthermore, in step (3), the electrodes of the electrochemical reactor are silicon-based boron-doped diamond electrodes, the pH of the wastewater is adjusted to 6-8, and the reaction is carried out at room temperature and pressure. The current density is set to 30-50 mA / cm². 2 The corresponding current is 3.6-6A.

[0019] Furthermore, in step (4), the sampling volume is 3 mL.

[0020] The present invention has the following beneficial effects: The method of this invention features simple process steps, can be carried out at room temperature and pressure, and the reaction parameters are easy to control. It requires no complex pretreatment steps and the necessary chemical reagents are inexpensive, making it suitable for large-scale industrial applications. The BDD electrode used continuously generates highly active hydroxyl radicals, which directly attack the fluorophore, cleaving the C=C and C=N conjugated double bonds, breaking down macromolecules into smaller acid molecules, and ultimately converting them into CO2, H2O, and NH4. + SO4 2- Inorganic end products are eliminated, achieving efficient COD removal and significantly reducing the color of the effluent.

[0021] In this invention, the chemical oxygen demand (COD) of fluorescent wastewater treated with a BDD electrode under composite electrolyte addition conditions can reach 0-46 mg / L, which meets the Class I standard (100 mg / L) in GB / T8978-1996 "Integrated Wastewater Discharge Standard". Furthermore, in the example, the molar ratio of anhydrous sodium sulfate to sodium chloride is 2:1, and the current density is 50 mA / cm². 2 Among them, it takes less time to reach the first-level standard, which is a significant advantage. Attached Figure Description

[0022] Figure 1 A flowchart of the fluorescent wastewater treatment process provided in an embodiment of the present invention; Figure 2 The curve showing the COD removal rate of the fluorescent wastewater treated in Example 1 as a function of time; Figure 3 The curve showing the change in COD removal rate of the fluorescent wastewater treated in Example 2 over time; Figure 4 The curve showing the change in COD removal rate of the fluorescent wastewater treated in Example 3 over time; Figure 5The curve showing the COD removal rate of the fluorescent wastewater treated in Comparative Example 1 as a function of time. Figure 6 The curve showing the COD removal rate of the fluorescent wastewater treated in Comparative Example 2 as a function of time.

[0023] Figure 7 The curve showing the COD removal rate of the fluorescent wastewater treated in Comparative Example 3 as a function of time. Detailed Implementation

[0024] The specific embodiments of the technical solution of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0025] This invention utilizes the combined action of a BDD electrode and a composite electrolyte. The highly reactive hydroxyl radicals generated by the BDD electrode can cleave fluorescent dye molecules, while the composite electrolyte achieves a dual oxidation system. SO4²⁻ is oxidized to S₂O₈²⁻ on the BDD anode surface, providing mild and continuous persulfate oxidation, reducing oxygen evolution side reactions, and buffering the anode surface pH to maintain voltage stability. Cl⁻ generates Cl₂ and ClO⁻, which rapidly electrophilically substitute and break bonds in fluorescent groups, achieving instantaneous decolorization and toxicity reduction, and shortening the reaction time. The composite electrolyte, through a synergistic mechanism, reduces cell voltage and energy consumption while avoiding the risk of perchlorate byproducts caused by NaCl alone. Simultaneously, SO4²⁻ inhibits anode passivation, and Cl⁻ inhibits calcium sulfate scaling, thereby extending electrode life.

[0026] This invention provides a composite electrolyte fluorescent wastewater treatment process based on a BDD electrode, see [link to relevant documentation]. Figure 1 The fluorescent wastewater used was the cleaning wastewater from fluorescent permeate solution used in the production of a company in Hunan Province. Its initial wastewater COD content was 3440 mg / L, pH value was 7, and conductivity was 129 μs / cm.

[0027] Example 1 Experimental steps for treating fluorescent wastewater using composite electrolytes based on BDD electrodes: 1. Filter the fluorescent wastewater. Place qualitative filter paper in a Buchner funnel, wet the filter paper with deionized water and fix it under vacuum. Slowly pour in the fluorescent wastewater and start filtration. Collect the filtrate.

[0028] 2. Calculate the electrolyte dosage based on the total addition of anhydrous sodium sulfate and sodium chloride of 0.05 mol / L, with a molar ratio of 1:1 between anhydrous sodium sulfate and sodium chloride. Accurately weigh 1.78 g of anhydrous sodium sulfate and 0.73 g of sodium chloride, and slowly add them to 500 mL of filtered fluorescent wastewater while continuously stirring until the electrolyte is completely dissolved.

[0029] 3. Pump 500 mL of fluorescent wastewater with added electrolyte into the electrode reaction vessel, turn on the magnetic stirrer, and set the stirring speed to 350 r / min. Connect the DC power supply, adjust the pH of the reaction system to 7, and set the power supply current to 3.6 A, 4.8 A, and 6 A respectively. Turn on the reaction device and conduct three experiments in total.

[0030] 4. During the reaction, maintain a constant stirring rate and take a 3 mL sample every 0.5 h, recording the voltage, current, pH, temperature, and conductivity. Stop the reaction after 2.5 h. The electrochemical reactor is connected to an activated carbon gas adsorption device; the gas generated during electrolysis is adsorbed by the activated carbon before being discharged.

[0031] 5. COD tests were conducted on the collected water samples. The test results showed that the COD values ​​of the fluorescent wastewater treated for 2.5 hours using the treatment process of this embodiment were 36 mg / L, 40 mg / L, and 24 mg / L, respectively, which met the Class I standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard".

[0032] Based on the obtained water sample test results, a curve showing the change in COD removal rate over time was plotted as follows: Figure 2 As shown, the COD removal rate curves of the three experimental groups all exhibited a trend of rapid initial increase followed by slow growth, with the high current density group showing a significant advantage. The 30 mA / cm² experimental group achieved a removal rate of 0.54 after 0.5 h and reached 0.98 after 2.5 h. The 40 mA / cm² experimental group increased to 0.65 after 0.5 h and reached 0.98 after 2.5 h. The 50 mA / cm² experimental group achieved a removal rate as high as 0.74 after 0.5 h and reached 0.99 after 2.5 h. This demonstrates that the higher the current density, the faster the initial COD degradation rate, resulting in a slightly higher final removal rate and earlier attainment of emission standards.

[0033] Example 2 Experimental steps for treating fluorescent wastewater using composite electrolytes based on BDD electrodes: 1. Filter the fluorescent wastewater. Place qualitative filter paper in a Buchner funnel, wet the filter paper with deionized water and fix it under vacuum. Slowly pour in the fluorescent wastewater and start filtration. Collect the filtrate.

[0034] 2. Calculate the electrolyte dosage based on the total addition of anhydrous sodium sulfate and sodium chloride of 0.05 mol / L, with a molar ratio of anhydrous sodium sulfate to sodium chloride of 1:2. Accurately weigh 1.18 g of anhydrous sodium sulfate and 0.98 g of sodium chloride, and slowly add them to 500 mL of filtered fluorescent wastewater, stirring continuously until the electrolyte is completely dissolved.

[0035] 3. Pump 500 mL of fluorescent wastewater with added electrolyte into the electrode reaction vessel, turn on the magnetic stirrer, and set the stirring speed to 350 r / min. Connect the DC power supply, adjust the pH of the reaction system to 7, and set the power supply current to 3.6 A, 4.8 A, and 6 A respectively. Turn on the reaction device and conduct three experiments in total.

[0036] 4. During the reaction, maintain a constant stirring rate and take a 3 mL sample every 0.5 h, recording the voltage, current, pH, temperature, and conductivity. Stop the reaction after 2.5 h. The electrochemical reactor is connected to an activated carbon gas adsorption device; the gas generated during electrolysis is adsorbed by the activated carbon before being discharged.

[0037] 5. COD tests were conducted on the collected water samples. The test results showed that the COD values ​​of the fluorescent wastewater treated for 2.5 hours using the treatment process of this embodiment were 676 mg / L, 8 mg / L, and 0 mg / L, respectively, which met the Class I standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard".

[0038] Based on the obtained water sample test results, a curve showing the change in COD removal rate over time was plotted as follows: Figure 3 As shown, the COD removal rate in the experimental group with a current density of 30 mA / cm² initially increased rapidly, but then dropped sharply due to the accumulation of intermediate products generated during the rapid degradation at low current, which could not be further oxidized in time, accompanied by the back dissolution of some incompletely degraded pollutants. The COD removal rate in the experimental group with a current density of 40 mA / cm² was 0.71 at 0.5 h and reached 0.99 at 2.5 h. The COD removal rate in the experimental group with a current density of 50 mA / cm² increased steadily, achieving complete removal at 2.5 h.

[0039] Example 3 Experimental steps for treating fluorescent wastewater using composite electrolytes based on BDD electrodes: 1. Filter the fluorescent wastewater. Place qualitative filter paper in a Buchner funnel, wet the filter paper with deionized water and fix it under vacuum. Slowly pour in the fluorescent wastewater and start filtration. Collect the filtrate.

[0040] 2. Calculate the electrolyte dosage based on the total addition of anhydrous sodium sulfate and sodium chloride of 0.05 mol / L, with a molar ratio of anhydrous sodium sulfate to sodium chloride of 2:1. Accurately weigh 2.37 g of anhydrous sodium sulfate and 0.49 g of sodium chloride, and slowly add them to 500 mL of filtered fluorescent wastewater, stirring continuously until the electrolyte is completely dissolved.

[0041] 3. Pump 500 mL of fluorescent wastewater with added electrolyte into the electrode reaction vessel, turn on the magnetic stirrer, and set the stirring speed to 350 r / min. Connect the DC power supply, adjust the pH of the reaction system to 7, and set the power supply current to 3.6 A, 4.8 A, and 6 A respectively. Turn on the reaction device and conduct three experiments in total.

[0042] 4. During the reaction, maintain a constant stirring rate and take a 3 mL sample every 0.5 h, recording the voltage, current, pH, temperature, and conductivity. Stop the reaction after 2.5 h. The electrochemical reactor is connected to an activated carbon gas adsorption device; the gas generated during electrolysis is adsorbed by the activated carbon before being discharged.

[0043] 5. COD tests were conducted on the collected water samples. The test results showed that the COD values ​​of the fluorescent wastewater treated for 2.5 hours using the treatment process of this embodiment were 46 mg / L, 26 mg / L, and 0 mg / L, respectively, which met the Class I standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard".

[0044] Based on the obtained water sample test results, a curve showing the change in COD removal rate over time was plotted as follows: Figure 4 As shown, the COD removal rate curves of the three experimental groups all showed a trend of rapid increase followed by stabilization, and finally stabilized within the range that meets the first-level emission standards.

[0045] Comparative Example 1 Experimental steps for fluorescent wastewater treatment based on BDD electrodes: 1. Filter the fluorescent wastewater. Place qualitative filter paper in a Buchner funnel, wet the filter paper with deionized water and fix it under vacuum. Slowly pour in the fluorescent wastewater and start filtration. Collect the filtrate.

[0046] 2. Based on the reference electrolyte addition amount of 0.05 mol / L, calculate the amount of anhydrous sodium sulfate to be used, accurately weigh 3.55 g of anhydrous sodium sulfate, slowly add it to 500 mL of filtered fluorescent wastewater, and continue stirring until the electrolyte is completely dissolved.

[0047] 3. Pump 500 mL of fluorescent wastewater with added electrolyte into the electrode reaction vessel, turn on the magnetic stirrer, and set the stirring speed to 350 r / min. Connect the DC power supply, adjust the pH of the reaction system to 7, set the power supply current to 6 A, turn on the reaction apparatus, and conduct the experiment.

[0048] 4. During the reaction, maintain a constant stirring rate and take a 3 mL sample every 0.5 h, recording the voltage, current, pH, temperature, and conductivity. Stop the reaction after 2.5 h. The electrochemical reactor is connected to an activated carbon gas adsorption device; the gas generated during electrolysis is adsorbed by the activated carbon before being discharged.

[0049] COD tests were conducted on 5 water samples. The results showed that the COD value of the fluorescent wastewater treated with the comparative process for 2.5 hours was 327 mg / L, which only met the Class III standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard".

[0050] Based on the obtained water sample test results, a curve showing the change in COD removal rate over time was plotted as follows: Figure 5 As shown, at a current density of 50 mA / cm² 2 Under these conditions, the COD removal rate curve still steadily and gradually increases, without a rapid degradation stage. At 2.5 hours, the fluorescent wastewater effluent had a relatively high COD residue, with a COD removal rate of 0.90, which is higher than the COD removal rate at the same point in the example.

[0051] Comparative Example 2 Experimental steps for fluorescent wastewater treatment based on BDD electrodes: 1. Filter the fluorescent wastewater. Place qualitative filter paper in a Buchner funnel, wet the filter paper with deionized water and fix it under vacuum. Slowly pour in the fluorescent wastewater and start filtration. Collect the filtrate.

[0052] 2. Based on the reference electrolyte addition amount of 0.05 mol / L, calculate the amount of sodium chloride electrolyte to be used. Accurately weigh 1.46 g of sodium chloride and slowly add it to 500 mL of filtered fluorescent wastewater. Stir continuously until the electrolyte is completely dissolved.

[0053] 3. Pump 500 mL of fluorescent wastewater with added electrolyte into the electrode reaction vessel, turn on the magnetic stirrer, and set the stirring speed to 350 r / min. Connect the DC power supply, adjust the pH of the reaction system to 7, set the power supply current to 6 A, turn on the reaction apparatus, and conduct the experiment.

[0054] 4. During the reaction, maintain a constant stirring rate and take a 3 mL sample every 0.5 h, recording the voltage, current, pH, temperature, and conductivity. Stop the reaction after 2.5 h. The electrochemical reactor is connected to an activated carbon gas adsorption device; the gas generated during electrolysis is adsorbed by the activated carbon before being discharged.

[0055] COD tests were conducted on 5 water samples. The results showed that the COD value of the fluorescent wastewater treated with the comparative process for 2.5 hours was 126 mg / L, which meets the Class II standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard".

[0056] Based on the obtained water sample test results, a curve showing the change in COD removal rate over time was plotted as follows: Figure 6As shown, the COD removal effect of this comparative example is better than that of Comparative Example 1, but slightly worse than that of the treatment process in the embodiment. The effluent temperature after treatment is very high. Cooling treatment would increase costs, while not cooling treatment may damage the electrodes.

[0057] Comparative Example 3 Experimental steps for treating fluorescent wastewater using composite electrolytes based on BDD electrodes: 1. Filter the fluorescent wastewater. Place qualitative filter paper in a Buchner funnel, wet the filter paper with deionized water and fix it under vacuum. Slowly pour in the fluorescent wastewater and start filtration. Collect the filtrate.

[0058] 2. Calculate the electrolyte dosage based on the total addition of anhydrous sodium sulfate and sodium chloride of 0.05 mol / L, with a molar ratio of anhydrous sodium sulfate to sodium chloride of 2:1. Accurately weigh 2.37 g of anhydrous sodium sulfate and 0.49 g of sodium chloride, and slowly add them to 500 mL of filtered fluorescent wastewater, stirring continuously until the electrolyte is completely dissolved.

[0059] 3. Pump 500 mL of fluorescent wastewater with added electrolyte into the electrode reaction vessel, turn on the magnetic stirrer, and set the stirring speed to 350 r / min. Connect the DC power supply, adjust the pH of the reaction system to 7, set the power supply current to 2.4 A, turn on the reaction apparatus, and conduct the experiment.

[0060] 4. During the reaction, maintain a constant stirring rate and take a 3 mL sample every 0.5 h, recording the voltage, current, pH, temperature, and conductivity. Stop the reaction after 2.5 h. The electrochemical reactor is connected to an activated carbon gas adsorption device; the gas generated during electrolysis is adsorbed by the activated carbon before being discharged.

[0061] 5. COD tests were conducted on the collected water samples. The test results showed that the COD value of the fluorescent wastewater treated for 2.5 hours using the treatment process of this embodiment was 115 mg / L, which meets the secondary standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard".

[0062] Based on the obtained water sample test results, a curve showing the change in COD removal rate over time was plotted as follows: Figure 7 As shown, in comparative embodiment 3, at a current density of 20 mA / cm², 2 In this case, the COD removal effect decreased significantly, and the COD removal rate was lower than that of Example 3 at the same time.

[0063] In summary, this invention provides a simple, low-cost, and highly effective fluorescent wastewater treatment process, employing an anhydrous sodium sulfate to sodium chloride molar ratio of 2:1 and a current density of 50 mA / cm². 2The residual COD value of the fluorescent wastewater treated by the BDD electrode can reach 0-46 mg / L, which meets the Class I standard in GB / T8978-1996 "Integrated Wastewater Discharge Standard".

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite electrolyte fluorescent wastewater treatment process based on BDD electrodes, characterized in that, Includes the following steps: (1) Use 10µm qualitative filter paper to remove slag from fluorescent wastewater; (2) Add a certain mass of anhydrous sodium sulfate and sodium chloride to the filtered fluorescent wastewater and stir until completely dissolved; (3) The dissolved fluorescent wastewater was pumped into the electrochemical reactor, with a total of 500 mL of wastewater pumped in. The effective electrode area of ​​the reactor was 100-150 cm². 2 ; (4) Set the power supply current to 3.6-6A, turn on the DC power supply, and periodically sample and analyze the wastewater; (5) The electrochemical reactor is directly connected to the activated carbon gas adsorption device, and the gas generated during the electrolysis process is adsorbed by the activated carbon.

2. The processing technology according to claim 1, characterized in that, In step (1), the slag removal filtration is carried out by laying qualitative filter paper in a Buchner funnel, wetting the filter paper with deionized water and fixing it under vacuum, and then performing vacuum filtration.

3. The processing technology according to claim 1, characterized in that, In step (2), the total amount of anhydrous sodium sulfate and sodium chloride added is 0.05 mol / L, and the molar ratio of the two is 1:2-2:

1.

4. The processing technology according to claim 1, characterized in that, In step (3), the anode of the electrochemical reactor is a BDD electrode, the cathode is a Ti electrode, the pH of the wastewater is adjusted to 6-8, the reaction is carried out at 20-30℃ and 100kPa, and the current density is set to 30-50mA / cm². 2 The corresponding current is 3.6-6A.

5. The processing technology according to claim 1, characterized in that, The sampling volume in step (4) is 3-4 mL.

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