An electrochemical method and system for mineralizing fully / polyhalogenated organic matter in water

Abstract

The present invention discloses an electrochemical method and system for mineralizing fully / polyhalogenated organic matter in water. The method comprises the following steps: adding an electrolyte and hydrogen peroxide to wastewater containing fully / polyhalogenated organic matter and mixing them uniformly to obtain a mixed solution A; passing the mixed solution A and ozone into a mixer and mixing them uniformly to obtain a mixed solution B; passing the mixed solution B into a permeation reactor, using an inert electrode as an anode and a porous electrode as a cathode, and performing sufficient electrolysis to achieve the mineralization of the fully / polyhalogenated organic matter in the wastewater. The present invention is simple to operate, does not require the addition of metal ions, and does not require the use of expensive electrode materials. During the reaction, the morphology and distribution of the alkaline diffusion layer can be controlled by adjusting the current density and the hydraulic state of the overflow, thereby controlling the generation of oxidizing and reducing species, achieving efficient mineralization of the fully / polyhalogenated organic matter, having good practical application value, and making the treatment of fully / polyhalogenated organic matter more economical and environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of advanced oxidation water treatment, and in particular relates to an electrochemical method and system for mineralizing fully / polyhalogenated organic matter in water. Background Art

[0002] Per- and polyhalogenated organic compounds (PHOs) are a special class of pollutants. The halogens in their molecular structures are highly electronegative, making them difficult to remove through simple oxidation. Typical PHOs include perfluorooctanoic acid / sulfonic acid (PFOA / PFOS), polychlorinated phenols, and polybrominated diphenyl ethers (PBDEs), which pose a serious threat to both the environment and human health.

[0003] Ozone-hydrogen peroxide technology is a mature ozone advanced oxidation water treatment technology that can produce a variety of active species, including strong oxidizing and reducing species, to degrade fully / polyhalogenated organic matter. However, in actual application, the direct reaction rate between hydrogen peroxide molecules and ozone is extremely low, which limits the treatment efficiency of ozone-hydrogen peroxide technology. The ionization product of hydrogen peroxide, HO2 - Can produce chain reaction with ozone molecules, and then generate OH and Therefore, the ionization of hydrogen peroxide is a key step in its chain reaction with ozone. However, the pKa of hydrogen peroxide is 11.8. Under neutral or weakly alkaline conditions, the degree of ionization of hydrogen peroxide is low, which has become a major bottleneck restricting the application of ozone-hydrogen peroxide technology.

[0004] Although advanced oxidation processes involving electrocatalytic ozone-hydrogen peroxide processes have been reported, such as CN114716001A, which discloses an apparatus and method for in-situ electrogenerated hydrogen peroxide in combination with ozone to treat refractory organic matter, these devices, however, require high electrical energy input, resulting in high costs. Furthermore, they place high demands on electrode materials, resulting in poor electrode stability. Furthermore, due to limitations in oxygen mass transfer, the generated hydrogen peroxide concentration is low, making it difficult to meet the reducing conditions required for dehalogenation of per- and polyhalogenated organic matter. Therefore, addressing the extremely low direct reaction rate between hydrogen peroxide molecules and ozone to improve the efficiency of ozone-hydrogen peroxide organic matter treatment and achieve efficient mineralization of per- and polyhalogenated organic matter has become an urgent issue. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide an electrochemical method for mineralizing fully / polyhalogenated organic matter in water, which solves the problem of extremely low direct reaction rate of hydrogen peroxide molecules and ozone in the prior art, and simultaneously generates oxidizing and reducing species to efficiently mineralize fully / polyhalogenated organic matter.

[0006] Furthermore, the present invention also provides an electrochemical system for implementing the above method.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] An electrochemical method for mineralizing fully / polyhalogenated organic matter in water comprises the following steps:

[0009] (1) adding electrolyte and hydrogen peroxide to wastewater containing fully / polyhalogenated organic matter and mixing them uniformly to obtain a mixed solution A;

[0010] (2) introducing the mixed solution A and ozone into a mixer and mixing them uniformly to obtain a mixed solution B;

[0011] (3) The mixed solution B is introduced into an electrochemical reactor, with an inert electrode as the anode and a porous electrode as the cathode, and is fully electrolyzed to achieve the mineralization of the fully / polyhalogenated organic matter in the wastewater; the anode and the cathode are arranged vertically from top to bottom, and the mixed solution B is introduced into the electrochemical reactor, first flowing through the anode and then flowing from the anode to the cathode.

[0012] Furthermore, in step (1), the concentration of hydrogen peroxide in the mixed solution A is 10 to 100 mmol / L. A hydrogen peroxide concentration higher than this range will result in a decrease in the oxidizing ability during the treatment process, because hydrogen peroxide itself reacts with ·OH, thereby consuming oxidizing species; while a hydrogen peroxide concentration lower than this range will result in an inability to effectively activate ozone to produce active species, resulting in a waste of ozone in the treatment process and a decrease in treatment effect.

[0013] Furthermore, in step (1), the concentration of the electrolyte in the mixed solution A is 1 to 100 mmol / L. If the electrolyte concentration is lower than this range, an electrical circuit cannot be formed in the electrochemical reactor, resulting in an inability to carry out the electrochemical reaction and a decrease in the treatment effect. If the electrolyte concentration is higher than this range, salt precipitation occurs, posing a risk of clogging the reactor. Therefore, the electrolyte concentration of the reaction solution should be 1 to 100 mmol / L.

[0014] Furthermore, in step (2), the ozone concentration introduced into the mixer is 10 to 100 mg / L, and the gas flow rate is 0.1 to 0.5 L / min. An ozone concentration below this range will result in a reduced efficiency of ozone dissolving in water, because ozone dissolving in water obeys Henry's law and is proportional to its partial pressure in the gas phase. Low concentrations will result in it being unable to effectively dissolve in water and participate in the reaction; if the concentration is higher than this range, ozone will not be utilized in time and will overflow, resulting in reduced efficiency, high energy consumption, and poor economic efficiency. If the gas flow rate is lower than this range, the ozone gas and the aqueous solution will not be fully mixed, resulting in a reduced treatment effect; if it is higher than this range, the proportion of gas in the reactor will be too large, occupying the reaction area and resulting in a reduced treatment efficiency.

[0015] Furthermore, in step (3), the mixed solution B is introduced into the electrochemical reactor at a pressure of 0.01 to 0.3 MPa.

[0016] Furthermore, in step (3), the current density of electrolysis is 1-10 mA / cm 2 .

[0017] Furthermore, in step (3), the inert electrode includes titanium-plated platinum or ruthenium-iridium electrode; and the porous electrode includes a metal electrode, a metal oxide electrode or a carbon-based electrode.

[0018] Furthermore, the electrolyte includes one or more electrolytes selected from sulfate, chloride, and carbonate.

[0019] Furthermore, the carbon-based electrode includes graphite, activated carbon fiber, carbon nanotube or graphene.

[0020] An electrochemical system for mineralizing fully / polyhalogenated organic matter in water comprises a wastewater tank, an ozone generator, a water ejector, and a penetrating reactor. The liquid outlet of the wastewater tank and the gas outlet of the ozone generator are connected to the feed port of the water ejector via a liquid outlet pipe and a gas outlet pipe, respectively. The discharge port of the water ejector is connected to the liquid inlet pipe of the penetrating reactor via a pipe, and the gas inlet of the ozone generator is connected to an oxygen cylinder via a pipe. A water pump, a pressure reducing valve, and a pressure gauge are sequentially provided on the liquid outlet pipe along the direction of liquid flow; and an ozone detector and a gas flow meter are sequentially provided on the gas outlet pipe along the direction of gas flow.

[0021] The penetrating reactor includes an upper cover and a lower cover, which form a cylindrical cavity when closed. A titanium mesh support layer, a porous cathode, and a hollow titanium foil are arranged in sequence from bottom to top in the lower cover. An inert anode is installed at the top of the upper cover, and a sealing gasket is arranged between the upper and lower covers so that the penetrating reactor can form a good seal when the upper and lower covers are closed. A liquid inlet pipe is provided on a side wall of the upper cover, and a lower chamber liquid outlet pipe is provided on a side wall of the lower cover. The penetrating reactor also includes a power supply, the positive electrode of the power supply is connected to the inert anode through an anode terminal, and the negative electrode of the power supply is connected to the hollow titanium foil through a wire.

[0022] Furthermore, an upper chamber liquid outlet pipe is provided on the other side wall of the upper cover, and the liquid outlet is connected to the liquid inlet of the wastewater tank through a pipeline.

[0023] Furthermore, a hydrogen peroxide dosing device is provided above the wastewater pool.

[0024] Working principle: The electrochemical method of the present invention for mineralizing fully / polyhalogenated organic matter in water adopts a penetrating reactor for electrolysis. When the porous cathode is energized, an alkaline diffusion layer can be formed between the cathode and the surrounding area, providing a local strong alkaline environment. The alkaline diffusion layer near the cathode can promote the ionization of hydrogen peroxide, thereby enhancing the ozone-hydrogen peroxide process and generating oxidizing (·OH) and reducing ( · H. ) species, and quickly mineralize fully / polyhalogenated organic matter. In this process, the present invention regulates the pH and distribution of the alkaline diffusion layer by adjusting the hydraulic state and current density, thereby regulating the generation of oxidizing and reducing species. By adjusting the wastewater inflow pressure, the hydraulic conditions when the water flows through the porous cathode can be adjusted, thereby optimizing the activation efficiency of ozone in the cathode alkaline diffusion layer and regulating the generation of oxidizing and reducing active species; at the same time, the electric field intensity in the reactor can be regulated by adjusting the current density of the DC power supply, thereby regulating the pH of the electrode surface, so as to achieve the regulation of ozone in the cathode alkaline diffusion layer to produce oxidizing and reducing species and the degradation and mineralization of fully / polyhalogenated organic matter.

[0025] Hydrogen peroxide ionizes in a strong alkaline environment to produce , and the generated It reacts quickly with ozone to generate oxidizing and reducing active species through chain reactions to degrade fully / polyhalogenated organic matter.

[0026] The main pathways for the generation of active species are:

[0027] (1) Generation of reducing active species:

[0028]

[0029] e - +H + → · H

[0030]

[0031] (2) Generation of oxidative active species:

[0032]

[0033]

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The electrochemical method of the present invention for mineralizing fully / polyhalogenated organic matter in water, on the one hand, achieves efficient removal of fully / polyhalogenated organic matter in mineralized water by combining ozone oxidation with electrochemical treatment technology; on the other hand, by precisely controlling the current density and overflow pressure, fine regulation of the morphology and distribution of the alkaline diffusion layer is achieved. This regulation strategy not only optimizes the production of oxidizing and reducing active species in the ozone-hydrogen peroxide process, but also achieves efficient mineralization of fully / polyhalogenated organic matter with lower energy input. The present invention is simple to operate, does not require the addition of metal ions, and does not require the use of expensive electrode materials. It has good practical value and makes the treatment of fully / polyhalogenated organic matter more economical and environmentally friendly. Compared with traditional treatment methods, the method of the present invention reduces operating costs and environmental impact while ensuring a high mineralization rate (up to 90% or more), providing a new efficient and environmentally friendly way to treat wastewater containing fully / polyhalogenated organic matter.

[0036] 2. The electrochemical system for mineralizing fully / polyhalogenated organic matter in water uses a porous cathode in a penetrating reactor to effectively enrich fully / polyhalogenated organic matter and efficiently degrades it using oxidative and reductive species generated by ozone and hydrogen peroxide. The porous cathode's large surface area and abundant pores not only promote localized accumulation of pollutants but also create a strongly alkaline environment, accelerating the ionization of hydrogen peroxide and its reaction with ozone, thereby significantly improving the degradation efficiency of fully / polyhalogenated organic matter. This design makes the electrochemical process more efficient, reducing processing time and energy consumption.

[0037] 3. The electrochemical system for mineralizing fully / polyhalogenated organic matter in water of the present invention has a unique design of a penetrating reactor. It uses a porous cathode to enrich pollutants and create a local strong alkaline environment. This promotes the rapid reaction of hydrogen peroxide ionization and ozone, generating a large number of oxidizing and reducing active species, significantly enhancing the degradation efficiency of organic matter. At the same time, by adjusting the overflow pressure and current intensity, the strength and distribution of the alkaline diffusion layer, as well as the alkalinity range and intensity of the porous cathode surface, can be flexibly controlled, thereby optimizing the treatment process and reducing energy input. In addition, the setting of the circulating treatment system further improves the treatment effect of wastewater and ensures the water quality of the effluent. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a time-removal rate diagram of PFOA in wastewater after electrochemical treatment in Example 1, Comparative Examples 1 and 2.

[0039] Figure 2 This is a graph showing the TOC removal rate of PFOA in wastewater after electrochemical treatment in Example 1, Comparative Examples 1 and 2.

[0040] Figure 3 This is a time-removal rate diagram of PFOA in wastewater after electrochemical treatment in Examples 1, 2, and 3.

[0041] Figure 4 This is a graph showing the TOC removal rate of PFOA in wastewater after electrochemical treatment in Examples 1, 2, and 3.

[0042] Figure 5 Graph showing the removal rates of various fully / polyhalogenated organic compounds in wastewater after electrochemical treatment in Examples 4 to 7.

[0043] Figure 6 This is a time-removal rate diagram of PFOA in wastewater after electrochemical treatment in Examples 1, 8, and 9.

[0044] Figure 7 This is a graph showing the TOC removal rate of PFOA in wastewater after electrochemical treatment in Examples 1, 8, and 9.

[0045] Figure 8 is the pH value of the wastewater after electrochemical treatment in Example 8.

[0046] Figure 9 It is a schematic structural diagram of the electrochemical system for mineralizing full / polyhalogenated organic matter in water according to the present invention.

[0047] Figure 9 Among them, 1. Hydrogen peroxide dosing device; 2. Wastewater tank; 3. Water pump; 4. Pressure reducing valve; 5. Pressure gauge; 6. Water ejector; 7. DC power supply; 8. Liquid inlet pipe; 9. Anode terminal; 10. Upper cover; 11. Inert anode; 12. Upper chamber liquid outlet pipe; 13. Sealing gasket; 14. Hollow titanium foil; 15. Porous cathode; 16. Lower chamber liquid outlet pipe; 17. Titanium mesh support layer; 18. Lower cover; 19. Gas flow meter; 20. Ozone detector; 21. Ozone generator; 22. Oxygen cylinder; 23. Penetrating reactor. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0049] The fully / polyhalogenated organic compounds described in the present invention are organic compounds in which the hydrogen atoms in the compounds are replaced by one or more halogens (fluorine, chlorine, bromine, iodine), mainly including: perfluorinated or partially fluorinated compounds (PFCs), chlorinated organic compounds (COCs) and brominated organic compounds (BOCs).

[0050] 1. Implementation

[0051] Example 1

[0052] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water to treat PFOA-containing wastewater; the method comprises the following steps:

[0053] (1) Prepare a 10 mg / L PFOA solution before the experiment;

[0054] (2) adding anhydrous sodium sulfate and hydrogen peroxide to the PFOA solution and mixing them uniformly to obtain a mixed solution A; the concentration of anhydrous sodium sulfate in the mixed solution A is 1 mmol / L, and the concentration of hydrogen peroxide is 20 mmol / L;

[0055] (3) Mixed solution A and ozone are introduced into a water ejector and mixed evenly to obtain mixed solution B; the concentration of ozone introduced into the water ejector is 80 mg / L, and the gas flow rate is 0.2 L / min;

[0056] (4) The mixed solution B was introduced into the electrochemical reactor at a pressure of 0.1 MPa, with a titanium-plated platinum electrode as the anode and an activated carbon fiber as the cathode. The current density was 10 mA / cm 2 The mineralization of the fully / polyhalogenated organic matter in the wastewater can be achieved by fully electrolyzing under the conditions; the anode and cathode in the electrochemical reactor are arranged vertically from top to bottom, and the mixed solution B is introduced into the electrochemical reactor, first flowing through the anode, and then flowing from the anode to the cathode.

[0057] Example 2

[0058] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 1, except that the current density during electrolysis is 5 mA / cm 2 .

[0059] Example 3

[0060] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 1, except that the current density during electrolysis is 1 mA / cm 2 .

[0061] Example 4

[0062] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water to treat wastewater containing diclofenac; the method comprises the following steps:

[0063] (1) Prepare 20 μmol / L diclofenac solution before the experiment;

[0064] (2) adding anhydrous sodium sulfate and hydrogen peroxide to the PFOA solution and mixing them uniformly to obtain a mixed solution A; the concentration of anhydrous sodium sulfate in the mixed solution A is 1 mmol / L, and the concentration of hydrogen peroxide is 10 mmol / L;

[0065] (3) Mixed solution A and ozone are introduced into a water ejector and mixed evenly to obtain mixed solution B; the concentration of ozone introduced into the water ejector is 50 mg / L, and the gas flow rate is 0.2 L / min;

[0066] (4) The mixed solution B was introduced into the electrochemical reactor at a pressure of 0.1 MPa, with a titanium-plated platinum electrode as the anode and activated carbon fiber as the cathode. 2 The mineralization of the fully / polyhalogenated organic matter in the wastewater can be achieved by fully electrolyzing under the conditions; the anode and cathode in the electrochemical reactor are arranged vertically from top to bottom, and the mixed solution B is introduced into the electrochemical reactor, first flowing through the anode, and then flowing from the anode to the cathode.

[0067] Example 5

[0068] This example provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 4, except that diclofenac is replaced by p-chlorobenzoic acid.

[0069] Example 6

[0070] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 4, except that diclofenac is replaced by ibuprofen.

[0071] Example 7

[0072] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 4, except that diclofenac is replaced by 2,4-dichlorophenoxyacetic acid.

[0073] Example 8

[0074] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 1, except that the pressure is adjusted to 0.2 MPa.

[0075] Example 9

[0076] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 1, except that the pressure is adjusted to 0.3 MPa.

[0077] Example 10

[0078] This embodiment provides an electrochemical method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 1, except that the following device of the present invention is used for the treatment.

[0079] In the penetrating reactor of this embodiment, the pH values ​​of the inlet water, the outlet water of the upper chamber, and the outlet water of the lower chamber are as follows: Figure 8 As shown by Figure 8 The inlet pH was 5.2, the outlet pH of the upper chamber was 2.9, and the outlet pH of the lower chamber was 12.1. These results indicate that the penetrating reactor can provide an alkaline environment for the generation of oxidative and reductive active species, promoting the degradation of fully and polyhalogenated organic matter.

[0080] Comparative Example 1

[0081] This comparative example provides a method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 1, except that no electricity is applied for electrolysis.

[0082] Comparative Example 2

[0083] This comparative example provides a method for mineralizing fully / polyhalogenated organic matter in water. The main steps are the same as those in Example 1, except that hydrogen peroxide is not added to the wastewater.

[0084] 2. Data Analysis

[0085] 1. Effects of power conditions and hydrogen peroxide on organic matter degradation

[0086] The time-removal rate of PFOA in the wastewater after electrochemical treatment of Example 1 of the present invention and Comparative Examples 1 and 2 is as follows Figure 1 As shown by Figure 1 It can be seen that after 60 minutes of treatment, the PFOA removal rate of the ozone-hydrogen peroxide process enhanced by the alkaline diffusion layer in Example 1 of the present invention is 99.0%, while the PFOA removal rate of the ozone-hydrogen peroxide process in Comparative Example 1 is 25.6%, and the PFOA removal rate of the electro-ozone process in Comparative Example 2 is 47.5%.

[0087] Furthermore, the TOC removal rate of PFOA in the wastewater after electrochemical treatment of Example 1 of the present invention and Comparative Examples 1 and 2 is shown in FIG. Figure 2 As shown by Figure 2 It can be seen that after 60 minutes of treatment, the TOC removal rate of PFOA by the ozone-hydrogen peroxide process enhanced by the alkaline diffusion layer in Example 1 of the present invention is 92.6%, the TOC removal rate of PFOA by the ozone-hydrogen peroxide process in Comparative Example 1 is 10.6%, and the TOC removal rate of PFOA by the electro-ozone process in Comparative Example 2 is 23.8%.

[0088] It can be seen that compared with the case where no power is applied and no hydrogen peroxide is added, the addition of the alkaline diffusion layer of the present invention can greatly improve the efficiency of activating ozone, degrade PFOA in water, and effectively improve the TOC removal rate.

[0089] 2. Influence of current density

[0090] The time-removal rate of PFOA in wastewater after electrochemical treatment in Examples 1, 2, and 3 of the present invention is shown in the figure. Figure 3 As shown by Figure 3 It can be seen that after the 60 min reaction, the current density of Example 1 is 10 mA / cm 2 When the current density of Example 2 is 5 mA / cm 2 When the current density of Example 3 is 1 mA / cm 2 When , the removal rate of PFOA was 65.5%;

[0091] Furthermore, the TOC removal rate of PFOA in wastewater after electrochemical treatment in Examples 1, 2, and 3 of the present invention is shown in FIG. Figure 4 As shown by Figure 4 It can be seen that after the 60 min reaction, the current density of Example 1 is 10 mA / cm 2 When the TOC removal rate of PFOA is 92.6%, the current density of Example 2 is 5mA / cm 2 When the current density of Example 3 is 1 mA / cm 2 The TOC removal rate of PFOA was 19.4%.

[0092] It can be seen that when the current density is 1~10mA / cm 2 When the current density is 1mA / cm 2 When the organic matter degradation effect is poor, the preferred current density is 5-10 mA / cm 2 .

[0093] 3. Influence of organic matter types

[0094] The removal rates of various types of fully / polyhalogenated organic matter in wastewater after electrochemical treatment in Examples 4 to 7 of the present invention are shown in the figure below. Figure 5 As shown by Figure 5 The results show that the alkaline diffusion layer-enhanced ozone-hydrogen peroxide process achieved TOC removal efficiencies of 98.2%, 90.3%, 95.6%, and 92.6% for diclofenac, p-chlorobenzoic acid, ibuprofen, and 2,4-dichlorophenoxyacetic acid, respectively. This demonstrates that the electrochemical method of the present invention is suitable for the efficient degradation of various fully and polyhalogenated organic compounds.

[0095] 4. Influence of overcurrent pressure

[0096] The time-removal rate of PFOA in the wastewater after electrochemical treatment in Examples 1, 8 and 9 of the present invention is as follows: Figure 6 As shown by Figure 6It can be seen that after 60 minutes of reaction, when the overflow pressure of Example 1 is 0.1 MPa, the PFOA removal rate is 99.0%; when the current density of Example 8 is 0.2 MPa, the PFOA removal rate is 88.5%; when the current density of Example 9 is 0.3 MPa, the PFOA removal rate is 72.1%;

[0097] Furthermore, the TOC removal rate of PFOA in wastewater after electrochemical treatment in Examples 1, 8, and 9 of the present invention is shown in FIG. Figure 7 As shown by Figure 7 It can be seen that after 60 minutes of reaction, when the overflow pressure of Example 1 is 0.1 MPa, the TOC removal rate of PFOA is 92.6%; when the overflow pressure of Example 8 is 0.2 MPa, the TOC removal rate of PFOA is 69.9%; when the overflow pressure of Example 9 is 0.3 MPa, the TOC removal rate of PFOA is 42.8%.

[0098] It can be seen that when the current density is 0.1-0.3 MPa, the degradation of PFOA and the removal of TOC can be achieved, but when the overflow pressure is greater than 0.1 MPa, the degradation effect of organic matter is not good. The preferred overflow pressure is 0.1 MPa.

[0099] 3. The present invention also provides a system for realizing the electrochemical method of mineralizing full / polyhalogenated organic matter in water.

[0100] like Figure 9 As shown, an electrochemical system for mineralizing fully / polyhalogenated organic matter in water includes a wastewater tank 2, an ozone generator 21, a water ejector 6, and a penetrating reactor 23. The liquid outlet of the wastewater tank 2 and the gas outlet of the ozone generator 21 are connected to the feed port of the water ejector 6 via a liquid outlet pipe and a gas outlet pipe, respectively. The discharge port of the water ejector 6 is connected to the liquid inlet pipe 8 of the penetrating reactor 23 via a pipe. A hydrogen peroxide dosing device 1 is provided above the wastewater tank 2. The gas inlet of the ozone generator 21 is connected to an oxygen cylinder 22 via a pipe. A water pump 3, a pressure reducing valve 4, and a pressure gauge 5 are sequentially provided on the liquid outlet pipe along the direction of liquid flow. An ozone detector 20 and a gas flow meter 19 are sequentially provided on the gas outlet pipe along the direction of gas flow.

[0101] The penetrating reactor 23 includes an upper cover 10 and a lower cover 18. When the upper cover 10 and the lower cover 18 are closed, a cylindrical cavity is formed. Inside the lower cover 18, a titanium mesh support layer 17, a porous cathode 15, and a hollow titanium foil 14 are stacked in sequence from bottom to top; an inert anode 11 is installed at the top of the upper cover 10, and a sealing gasket 13 is provided between the upper cover 10 and the lower cover 18 so that the penetrating reactor 23 can form a good seal when the upper cover 10 and the lower cover 18 are closed; a liquid inlet pipe 8 is provided on a side wall of the upper cover 10, and a lower chamber liquid outlet pipe 16 is provided on the side wall of the lower cover 18; the penetrating reactor 23 also includes a DC power supply 7, the positive electrode of the DC power supply 7 is connected to the inert anode 11 via an anode terminal 9, and the negative electrode of the DC power supply 7 is connected to the hollow titanium foil 14 via a wire.

[0102] In a specific implementation, an upper chamber liquid outlet pipe 12 is provided on the other side wall of the upper cover 10 .

[0103] During specific implementation, the liquid outlet of the upper chamber liquid outlet pipe 12 is connected to the liquid inlet of the wastewater tank 2 through a pipeline.

[0104] In a specific implementation, the distance between the inert anode 11 and the porous cathode 15 is 1 cm, and the hydraulic retention time of the electrolyte in the reactor is 0.1 to 1 minute. A too short hydraulic retention time will result in the reaction solution not being able to fully react in the reactor. While a longer hydraulic retention time will allow the reaction solution to fully react and improve treatment efficiency, it will significantly increase energy consumption and reduce economic efficiency. Therefore, a moderate hydraulic retention time is preferred.

[0105] Working principle:

[0106] (1) Wastewater pretreatment and ozone generation:

[0107] Wastewater is first collected in a wastewater tank 2. A hydrogen peroxide dosing device 1, located above the wastewater tank 2, adds hydrogen peroxide to the wastewater as needed to enhance subsequent treatment. Oxygen supplied by an oxygen cylinder 22 is piped into an ozone generator 21, providing pressure. The ozone generator 21 converts the oxygen into ozone using methods such as high voltage or ultraviolet light.

[0108] (2) Mixing of wastewater and ozone:

[0109] Wastewater is pumped from the outlet of wastewater tank 2 by water pump 3 and flows along the outlet pipe. A pressure reducing valve 4 is installed along the pipe to regulate the water pressure and thus the hydraulic conditions in the penetrating reactor 23, and a pressure gauge 5 is used to monitor the water pressure within the pipe. Simultaneously, ozone generated by ozone generator 21 is output through the outlet pipe. An ozone detector 20 is installed along the pipe to monitor ozone concentration, and a gas flowmeter 19 is used to detect and regulate the ozone flow rate. The wastewater and ozone meet and mix at the water ejector 6. The water ejector 6 uses the negative pressure generated by the high-speed water flow to draw in ozone and thoroughly mix it with the wastewater, forming an ozone-containing wastewater solution.

[0110] (3) Electrochemical treatment:

[0111] The ozone-containing wastewater solution enters the penetration reactor 23 through a pipe. The penetration reactor 23 is composed of a cylindrical cavity formed by closing the upper cover 10 and the lower cover 18, and a titanium mesh support layer 17, a porous cathode 15 and a hollow titanium foil 14 are stacked in sequence inside. An inert anode 11 is installed on the top of the upper cover 10 and is connected to the positive electrode of the DC power supply 7. The hollow titanium foil 14 is connected to the negative electrode of the DC power supply 7 through a wire to form an electrolysis circuit. Under the action of pressure and gravity, the ozone-containing wastewater solution flows downward in the penetration reactor 23, flushing the porous cathode 15, and the fully / polyhalogenated organic matter is adsorbed on the surface of the porous cathode 15 to achieve enrichment. Under the action of the electric field, the rich pores of the porous cathode 15 have a local strong alkaline environment, and hydrogen peroxide is more easily ionized when flowing through the porous cathode 15, and its ionization product It can react rapidly with ozone, simultaneously generating oxidizing and reducing active species, rapidly degrading the electrolyte and the fully / polyhalogenated organic matter adsorbed on the surface of the porous cathode 15. In the entire system, the hydraulic state within the penetrating reactor 23 can be adjusted by adjusting the pipeline pressure, thereby regulating the flow rate on the surface of the porous cathode 15 and thus adjusting the strength and distribution of the alkaline diffusion layer. At the same time, the current intensity can also be adjusted to change the alkalinity range and strength on the surface of the porous cathode 15, thereby promoting the ionization of hydrogen peroxide, breaking the rate-limiting step of the ozone-hydrogen peroxide process, and significantly enhancing the ozone-hydrogen peroxide process with a small energy input to simultaneously generate oxidizing and reducing active species to degrade fully / polyhalogenated organic matter.

[0112] (4) Recycling of treated wastewater:

[0113] The treated wastewater is discharged from the lower chamber liquid outlet pipe 16 under the action of pressure.

[0114] During specific implementation, an upper chamber liquid outlet pipe 12 is also provided on the other side wall of the upper cover 10, so that under the action of water pressure, water can also flow out of the upper chamber liquid outlet pipe 12 and form a cross flow with the lower chamber liquid outlet pipe 16, thereby avoiding blockage of the liquid outlet pipe. At the same time, the liquid outlet of the upper chamber liquid outlet pipe 12 is connected to the liquid inlet of the wastewater tank 2 through a pipeline, forming a circulating treatment system. In this way, the treated wastewater can re-enter the wastewater tank 2 for further treatment, or be discharged or recycled according to the treatment effect. It can be seen that the present invention effectively removes full / polyhalogenated organic matter in mineralized water through the combination of ozone oxidation and electrochemical treatment, thereby improving the efficiency and effect of wastewater treatment.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An electrochemical method for mineralizing fully / polyhalogenated organic matter in water, characterized in that: The following steps are involved: (1) adding electrolyte and hydrogen peroxide to wastewater containing fully / polyhalogenated organic matter and mixing them uniformly to obtain a mixed solution A; (2) Mixed solution A and ozone are introduced into a mixer and mixed evenly to obtain mixed solution B; (3) The mixed solution B is introduced into an electrochemical reactor, with an inert electrode as the anode and a porous electrode as the cathode, and is fully electrolyzed to achieve the mineralization of the fully / polyhalogenated organic matter in the wastewater; the anode and the cathode are arranged vertically from top to bottom, and the mixed solution B is introduced into the electrochemical reactor, first flowing through the anode and then flowing from the anode to the cathode; The following electrochemical system is used: the electrochemical system includes a wastewater tank, an ozone generator, a water ejector and a penetrating reactor, the liquid outlet of the wastewater tank and the gas outlet of the ozone generator are connected to the feed port of the water ejector through a liquid outlet pipe and a gas outlet pipe respectively, the discharge port of the water ejector is connected to the liquid inlet pipe of the penetrating reactor through a pipe, and the gas inlet of the ozone generator is connected to the oxygen cylinder through a pipe; the liquid outlet pipe is provided with a water pump, a pressure reducing valve and a pressure gauge in sequence along the direction of liquid flow; the gas outlet pipe is provided with an ozone detector and a gas flow meter in sequence along the direction of gas flow; The penetrating reactor comprises an upper cover and a lower cover, which form a cylindrical cavity when closed. A titanium mesh support layer, a porous cathode, and a hollow titanium foil are sequentially arranged in the lower cover from bottom to top. An inert anode is installed at the top of the upper cover, and a sealing gasket is provided between the upper and lower covers so that the penetrating reactor can form a good seal when the upper and lower covers are closed. A liquid inlet pipe is provided on a side wall of the upper cover, and a lower chamber liquid outlet pipe is provided on a side wall of the lower cover. The penetrating reactor also includes a power supply, the positive electrode of the power supply is connected to the inert anode via an anode terminal, and the negative electrode of the power supply is connected to the hollow titanium foil via a wire. By adjusting the pipeline pressure, the hydraulic state in the penetrating reactor is adjusted, and then the flow rate on the porous cathode surface is controlled to adjust the strength and distribution of the alkaline diffusion layer. The alkaline range and strength of the porous cathode surface are changed by adjusting the current intensity, thereby promoting the ionization of hydrogen peroxide and breaking the rate-limiting step of the ozone-hydrogen peroxide process.

2. The electrochemical method for mineralizing full / polyhalogenated organic matter in water according to claim 1, characterized in that: In step (1), the concentration of hydrogen peroxide in the mixed solution A is 10-100 mmol / L.

3. The electrochemical method for mineralizing full / polyhalogenated organic matter in water according to claim 1, characterized in that: In the step (1), the concentration of the electrolyte in the mixed solution A is 1-100 mmol / L.

4. The electrochemical method for mineralizing full / polyhalogenated organic matter in water according to claim 1, characterized in that: In the step (2), the ozone concentration introduced into the mixer is 10-100 mg / L, and the gas flow rate is 0.1-0.5 L / min.

5. The electrochemical method for mineralizing full / polyhalogenated organic matter in water according to claim 1, characterized in that: In the step (3), the mixed solution B is introduced into the electrochemical reactor at a pressure of 0.01-0.3 MPa.

6. The electrochemical method for mineralizing full / polyhalogenated organic matter in water according to claim 1, characterized in that: In step (3), the current density of electrolysis is 1-10 mA / cm 2 .

7. The electrochemical method for mineralizing full / polyhalogenated organic matter in water according to claim 1, characterized in that: In the step (3), the inert electrode includes a titanium-plated platinum or ruthenium-iridium electrode; and the porous electrode includes a metal electrode, a metal oxide electrode or a carbon-based electrode.

8. The electrochemical method for mineralizing full / polyhalogenated organic matter in water according to claim 1, characterized in that: An upper chamber liquid outlet pipe is provided on the other side wall of the upper cover, and the liquid outlet is connected to the liquid inlet of the wastewater tank through a pipeline.

9. The electrochemical method for mineralizing full / polyhalogenated organic matter in water according to claim 8, characterized in that: A hydrogen peroxide dosing device is provided above the wastewater pool.

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