Perfluorooctane sulfonic acid in-situ repair multilayer porous electrode electrochemical oxidation device

Abstract

The invention relates to the technical field of sewage treatment, and discloses a perfluorooctyl sulfonic acid in-situ remediation multi-layer porous electrode electrochemical oxidation device which comprises a protective cover internally provided with a pipeline; the electrode plate is positioned below the protective cover, is parallel to the protective cover and is communicated with an external power supply; the reaction grid is located in underground water and fixedly connected between the protective cover and the electrode plate, the top end of the reaction grid is communicated with a water path in the protective cover, the bottom end of the reaction grid is electrically connected with the electrode plate, an oxidizing agent is injected into the reaction grid through a pipeline, and free radicals are generated through electrochemical oxidation; the free radicals are used for removing perfluorooctyl sulfonic acid pollutants in underground water. Aiming at a PFOS polluted site, efficient groundwater remediation can be achieved, a satisfactory pollutant removal effect can be achieved in a short time, efficient utilization of resources can be achieved, the method can be suitable for various groundwater environments, and it is ensured that the remedied groundwater meets the environmental protection requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, in particular to a perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device. Background Art

[0002] As a typical highly stable organic pollutant, PFOS was once widely used in industrial fields such as firefighting, electroplating, and textiles. The unique carbon-fluorine bond structure in its molecules makes it difficult to degrade in the natural environment and can migrate and spread through groundwater, causing large-scale pollution. Investigations of contaminated sites have shown that PFOS is not only present in the surface soil, but also easily penetrates into deep soil and groundwater systems, and its environmental behavior exhibits significant cross-media contamination characteristics. Due to the bioaccumulation and potential toxicity of PFOS, long-term exposure may cause health risks such as endocrine disruption and immunosuppression. Remediation of contaminated sites is imminent.

[0003] At present, the field of PFOS pollution remediation mainly faces two technical bottlenecks: First, the efficiency of existing treatment technologies is limited. Traditional ex situ remediation methods such as soil excavation treatment are not only complex and costly, but may also cause secondary pollution during transportation and disposal. Although groundwater extraction and treatment technology can quickly reduce the concentration of pollutants, it is not effective in removing PFOS and has poor long-term economic efficiency. Second, the collaborative treatment capacity of media is insufficient. Conventional remediation technologies mostly use a soil and groundwater separation treatment mode, which makes it difficult to block the continuous migration and interaction of pollutants between media. For example, the degradation efficiency of PFOS by chemical oxidation is limited by its chemical inertness, while physical adsorption technology can only achieve phase transfer of pollutants and cannot achieve complete removal.

[0004] In response to the above challenges, electrochemical oxidation technology has shown unique application potential. Electrochemical oxidation technology is an advanced oxidation process based on electrochemical principles. It uses an external electric field to drive the redox reaction at the electrode interface to achieve efficient degradation of pollutants. Its core mechanism includes two aspects: one is direct oxidation, that is, the pollutants are directly decomposed through electron transfer on the electrode surface; the other is indirect oxidation, which uses the strong oxidizing active species generated by electrochemical reactions (such as hydroxyl radicals ·OH, sulfate radicals SO4· - For difficult-to-degrade pollutants like PFOS, which contain high-energy C—F bonds, this technology uses targeted generation of highly reactive free radicals to gradually break down their molecular structure, ultimately achieving defluorination and mineralization, generating harmless products such as carbon dioxide and fluoride ions.

[0005] This technology uses active substances generated by electrode interface reactions to carry out targeted attacks on PFOS molecules, effectively breaking their stable CF bond structure. Compared with traditional methods, its advantages are: first, the reaction process does not require the addition of large amounts of chemical agents, significantly improving environmental compatibility; second, by adjusting electrochemical parameters, precise degradation of pollutants can be achieved, avoiding the risk of secondary pollution; third, it can simultaneously treat dissolved PFOS in soil leachate and groundwater, providing new ideas for solving the problem of cross-contamination of media. Currently, research on this technology focuses on electrode material optimization and reaction system design, aiming to improve treatment efficiency and expand its engineering application scenarios, providing more feasible solutions for PFOS pollution control in complex industrial sites.

[0006] Therefore, there is an urgent need for a perfluorooctane sulfonic acid in-situ repair multilayer porous electrode electrochemical oxidation device to solve the above problems. Summary of the Invention

[0007] The purpose of the present invention is to provide a perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device to solve the problems existing in the above-mentioned prior art.

[0008] To achieve the above-mentioned object, the present invention provides the following solution: The present invention provides a perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device, comprising:

[0009] A protective cover having a pipe disposed therein;

[0010] an electrode plate, located below the protective cover and arranged parallel to the protective cover, the electrode plate being connected to an external power source;

[0011] A reaction grid is located in the groundwater and is fixedly connected between the protective cover and the electrode plate. The top of the reaction grid is connected to the water channel in the protective cover, and the bottom of the reaction grid is electrically connected to the electrode plate. An oxidant is injected into the reaction grid through the pipeline to generate free radicals through electrochemical oxidation. The free radicals are used to remove perfluorooctane sulfonic acid pollutants in the groundwater.

[0012] According to a perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, the reaction grid includes a plurality of water purification units, and the plurality of water purification units are evenly distributed between the protective cover and the electrode plate in the vertical direction, and a purification transition chamber is formed between two adjacent water purification units.

[0013] According to a perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, the electrode plate includes a first base and a second base, the first base is fixedly connected to the top of the second base, and a plurality of electrode grooves are provided on the first base, the second base and the protective cover, the electrode grooves on the first base and the electrode grooves on the second base are coaxially connected, the electrode grooves on the first base are connected to the positive electrode of the power supply through a positive electrode line, and the electrode grooves on the second base are connected to the negative electrode of the power supply through a negative electrode line.

[0014] According to a perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, the water purification unit includes four layers of electrode column tubes that are nested layer by layer, and the two ends of the electrode column tubes are respectively connected to the electrode groove on the protective cover and the electrode groove on the electrode plate.

[0015] According to the perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, a plurality of small holes are opened on the electrode column tube.

[0016] According to the perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, the diameters of the four layers of electrode column tubes from inside to outside are 12.5 mm, 25 mm, 37.5 mm and 50 mm respectively.

[0017] According to the perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, the diameters of the small holes on the four layers of the electrode column tubes are 25 mm, 2.5 mm, 3.75 mm and 5 mm from the inside to the outside respectively.

[0018] According to a perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, the two ends of the pipeline are respectively connected to the output end of the dosing pump and the input end of the water pump, the input end of the dosing pump is connected to the dosing tank, and the output end of the water pump is connected to the liquid storage tank.

[0019] According to the perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, a plurality of through holes are opened on the protective cover, and the pipeline is connected to the water purification unit through the through holes.

[0020] According to the perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device provided by the present invention, the four layers of electrode column tubes are arranged from the outside to the inside in the order of positive electrode, negative electrode, positive electrode, and negative electrode.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] The present invention provides a multi-layer porous electrode electrochemical oxidation device for in-situ remediation of perfluorooctane sulfonic acid. When in use, the device is located in groundwater, and drugs are added or samples are taken into the reaction grid through a pipeline. When the water flows into the reaction grid or flows through the reaction grid, the pollutants are electrochemically oxidized or react with free radicals generated by the oxidant, and the pollutants are oxidized and removed. This application is aimed at PFOS-contaminated sites and can achieve efficient groundwater remediation. The multi-layer electrode electrochemical oxidation treatment can achieve a satisfactory pollutant removal effect in a short time. The remediation system will not interfere with normal production activities on the ground during operation. At the same time, it can achieve efficient resource utilization and is applicable to various groundwater environments. The efficient utilization of water resources, simplified operation process and convenient management method ensure that the remediated groundwater meets environmental protection requirements. It has strong practicality and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work.

[0024] Figure 1 It is a side view of the overall structure of the present invention;

[0025] Figure 2 It is a three-dimensional diagram of the overall structure of the present invention;

[0026] Figure 3 This is a schematic structural diagram of the water purification unit of the present invention;

[0027] Figure 4 This is a schematic diagram of the electrode slot distribution structure of the present invention;

[0028] Figure 5 Schematic diagram of the electrode plate structure of the present invention;

[0029] Among them, 1. Dosing tank; 2. Liquid storage tank; 3. Protective cover; 4. Water purification unit; 5. First base; 6. Second base; 7. Dosing pump; 8. Water pump; 9. Purification transition chamber; 10. Through hole; 11. Power supply; 12. Negative electrode line; 13. Positive electrode line; 14. Electrode slot; 15. Pipeline. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1:

[0033] Reference Figure 1-Figure 5 The present invention provides a perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device, comprising:

[0034] The protective cover 3 has a pipe 15 disposed therein;

[0035] The electrode plate is located below the protective cover 3 and is arranged parallel to the protective cover 3. The electrode plate is connected to the external power supply;

[0036] The reaction grid is located in the groundwater and is fixedly connected between the protective cover 3 and the electrode plate. The top of the reaction grid is connected to the water channel in the protective cover 3, and the bottom of the reaction grid is electrically connected to the electrode plate. The oxidant is injected into the reaction grid through the pipeline 15 to generate free radicals through electrochemical oxidation. The free radicals are used to remove perfluorooctane sulfonic acid pollutants in the groundwater.

[0037] In one embodiment of the present application, when in use, the device is located in groundwater, and drugs are added or samples are taken into the reaction grid through the pipe 15. When the water flows into the reaction grid or flows through the reaction grid, the pollutants are electrochemically oxidized or react with free radicals generated by the oxidant, and the pollutants are oxidized and removed.

[0038] According to a further optimized solution, the reaction grid includes a plurality of water purification units 4 , which are evenly distributed between the protective cover 3 and the electrode plate in the vertical direction, and a purification transition chamber 9 is formed between two adjacent water purification units 4 .

[0039] In one embodiment of the present application, a purification transition cavity 9 is formed between adjacent water purification units 4 and between the boundaries of the water purification unit 4 and the water cube.

[0040] A further optimized solution is provided, in which the electrode plate includes a first base 5 and a second base 6, the first base 5 is fixedly connected to the top of the second base 6, and a plurality of electrode grooves 14 are provided on the first base 5, the second base 6 and the protective cover 3. The electrode grooves 14 on the first base 5 and the electrode grooves 14 on the second base 6 are coaxially connected, the electrode grooves 14 on the first base 5 are connected to the positive pole of the power supply 11 through the positive line 13, and the electrode grooves 14 on the second base 6 are connected to the negative pole of the power supply 11 through the negative line 12.

[0041] In one embodiment of the present application, a first base 5 containing a positive electrode circuit is stacked with a second base 6 containing a negative electrode circuit, and the electrode grooves 14 of the two overlap, which can fix the electrodes. The upper and lower electrode grooves 14 are respectively connected to the positive electrode circuit 13 and the negative electrode circuit 12, and the positive and negative electrode circuits are externally connected to the power supply 11.

[0042] According to a further optimized solution, the water purification unit 4 includes four layers of electrode column tubes which are nested layer by layer, and both ends of the electrode column tubes are respectively connected to the electrode slots 14 on the protective cover 3 and the electrode slots 14 on the electrode plate.

[0043] In one embodiment of the present application, the electrode slot 14 is a four-circle concentric circle structure, which is compatible with the four-layer electrode column tube.

[0044] To further optimize the solution, a number of small holes are opened on the electrode column tube.

[0045] In one embodiment of the present application, water can flow through the small holes. When the water flows into the water purification unit 4 or flows through the water purification unit 4, the pollutants are electrochemically oxidized or react with free radicals generated by the oxidant, and the pollutants are oxidized and removed.

[0046] The solution was further optimized, with the diameters of the four-layer electrode column tubes from inside to outside being 12.5mm, 25mm, 37.5mm and 50mm respectively.

[0047] The solution was further optimized, and the diameters of the small holes on the four-layer electrode column tube were 25 mm, 2.5 mm, 3.75 mm, and 5 mm from the inside to the outside.

[0048] To further optimize the solution, both ends of the pipeline 15 are connected to the output end of the dosing pump 7 and the input end of the water pump 8 respectively, the input end of the dosing pump 7 is connected to the dosing tank 1, and the output end of the water pump 8 is connected to the liquid storage tank 2.

[0049] In one embodiment of the present application, the pipeline 15 is a dual-purpose pipeline for adding drugs and sampling. There are injection ports and extraction ports at both ends of the protective cover 3 respectively. The pipeline 15 line is designed to be sealed. When adding drugs, the extraction port is closed and the oxidant is added through the injection port. When sampling, the injection port is closed and the water sample is extracted through the extraction port.

[0050] According to a further optimized solution, a plurality of through holes 10 are provided on the protective cover 3 , and the pipe 15 is connected to the water purification unit 4 through the through holes 10 .

[0051] In one embodiment of the present application, the pipeline 15 is connected to the water purification unit 4 through the provided through hole 10, which is used for adding medicine to the water purification unit 4 or taking samples.

[0052] To further optimize the solution, the four-layer electrode column tube is arranged from the outside to the inside in the order of positive pole, negative pole, positive pole, and negative pole.

[0053] In one embodiment of the present application, there are 14 water purification units 4, each with a sampling hole, for a total of 14. During system operation, the water purification units 4 are sampled regularly to evaluate the ability of the water purification units 4 to remove pollutants.

[0054] Example 2:

[0055] Under laboratory conditions, simulated groundwater contaminated with PFOS was remediated. A plexiglass container measuring 400mm (length, width, and height) was filled with a 1:1 ratio of clay and quartz sand to simulate the subsurface soil and groundwater containing dissolved PFOS contaminants. A sampling port for the simulated groundwater was provided on the side of the container. The specific remediation steps are as follows:

[0056] Turn off dosing pump 7 and turn on water pump 8 to pump groundwater containing PFOS into liquid storage tank 2 at a flow rate of 10 mL / min. After the groundwater in liquid storage tank 2 exceeds 50 mL, turn off water pump 8 and measure the PFOS concentration in liquid storage tank 2, which is 12.6 mg / L.

[0057] Turn on the power supply 11 and adjust the current to 1A for pre-oxidation;

[0058] After 30 minutes of pre-oxidation, the dosing pump 7 is turned on at a flow rate of 10 mL / min, and 200 mM potassium persulfate in the dosing tank 1 is injected into the groundwater. At the same time, the current of the power supply 11 is adjusted to 2 A to carry out the oxidation reaction.

[0059] Every 10 minutes, pump 8 was turned on to pump groundwater containing PFOS into tank 2 at a flow rate of 10 mL / min. When the groundwater in tank 2 exceeded 50 mL, pump 8 was turned off and the PFOS concentration in tank 2 was measured. Subsequently, dosing pump 7 was turned on at a flow rate of 10 mL / min to inject 200 mM potassium persulfate from dosing tank 1 into the groundwater. This process was repeated.

[0060] The experiment showed that after 6 hours, the residual concentration of pollutants in the soil in liquid storage tank 2 and the simulated groundwater flowing through the seepage trough was significantly reduced, with the PFOS removal rate in the soil reaching 81.4%. After 24 hours, PFOS in the soil was completely removed. This demonstrates that the reactor of the present invention is effective in removing PFOS contaminants from groundwater, and the remediation technology of the present invention is simple and easy to operate.

[0061] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0062] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device, characterized in that: include: A protective cover (3) having a pipe (15) disposed therein; an electrode plate, located below the protective cover (3) and arranged parallel to the protective cover (3), the electrode plate being connected to an external power source; A reaction grid is located in groundwater and is fixedly connected between the protective cover (3) and the electrode plate. The top of the reaction grid is connected to the water channel in the protective cover (3), and the bottom of the reaction grid is electrically connected to the electrode plate. An oxidant is injected into the reaction grid through the pipeline (15) to generate free radicals through electrochemical oxidation. The free radicals are used to remove perfluorooctane sulfonic acid pollutants in the groundwater.

2. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 1, characterized in that: The reaction grid comprises a plurality of water purification units (4), wherein the plurality of water purification units (4) are evenly distributed between the protective cover (3) and the electrode plate in a vertical direction, and a purification transition chamber (9) is formed between two adjacent water purification units (4).

3. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 2, characterized in that: The electrode plate comprises a first base (5) and a second base (6), wherein the first base (5) is fixedly connected to the top of the second base (6), and a plurality of electrode slots (14) are provided on the first base (5), the second base (6) and the protective cover (3), wherein the electrode slots (14) on the first base (5) and the electrode slots (14) on the second base (6) are coaxially connected, wherein the electrode slots (14) on the first base (5) are connected to the positive electrode of the power supply (11) via a positive line (13), and the electrode slots (14) on the second base (6) are connected to the negative electrode of the power supply (11) via a negative line (12).

4. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 3, characterized in that: The water purification unit (4) comprises four layers of electrode column tubes which are nested layer by layer, and both ends of the electrode column tubes are respectively connected to the electrode grooves (14) on the protective cover (3) and the electrode grooves (14) on the electrode plate.

5. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 4, characterized in that: The electrode column tube is provided with a plurality of small holes.

6. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 4, characterized in that: The diameters of the four layers of electrode column tubes from inside to outside are 12.5 mm, 25 mm, 37.5 mm and 50 mm respectively.

7. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 5, characterized in that: The diameters of the small holes on the four layers of electrode column tubes are 1.25 mm, 2.5 mm, 3.75 mm and 5 mm from the inside to the outside respectively.

8. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 1, characterized in that: The two ends of the pipeline (15) are respectively connected to the output end of the dosing pump (7) and the input end of the water pump (8), the input end of the dosing pump (7) is connected to the dosing tank (1), and the output end of the water pump (8) is connected to the liquid storage tank (2).

9. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 2, characterized in that: The protective cover (3) is provided with a plurality of through holes (10), and the pipeline (15) is connected to the water purification unit (4) through the through holes (10).

10. The perfluorooctane sulfonic acid in-situ repair multi-layer porous electrode electrochemical oxidation device according to claim 4, characterized in that: The four layers of electrode column tubes are arranged from outside to inside in the order of positive electrode, negative electrode, positive electrode, and negative electrode.

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