An electrochemical reaction system and its application

Abstract

This invention relates to an electrochemical reaction system and its application, comprising an electrode assembly and a cathode chamber and an anode chamber separated by the electrode assembly. The electrode assembly mainly includes a cathode, a porous aeration component, and an anode, wherein the porous aeration component is located between the cathode and the anode and is a mesh structure composed of several interwoven aeration tubes, with an aeration port on the side facing the anode chamber, and the rest sealed. The reaction system provided by this invention can achieve isolation between the anode and cathode chambers and rapid diffusion of acidic regions, exhibiting excellent alkalinity removal performance when used for wastewater alkalinity removal, and can also improve electrode lifespan.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to an electrochemical reaction system and its application. Background Technology

[0002] Electrochemical technology is gaining increasing popularity among researchers due to its environmentally friendly nature, ease of operation, and lack of secondary pollution. Utilizing the redox properties of its anodic and cathodic electrodes, it can be widely used for pollutant removal, including common applications such as electrochemical degradation of organic matter, electrochemical reduction of nitrates, and electrochemical descaling. Furthermore, it has broad applications in electrochemically enhanced biochemical processes, electrochemical hydrogen peroxide production, and electrochemical acid-base production.

[0003] CN106277369A discloses an electrochemical scale inhibition method, comprising: 1) dividing an electrolytic cell into an anode chamber and a cathode chamber via a diaphragm, with the anode and cathode placed in the anode chamber and cathode chamber respectively; 2) allowing the water to be treated to flow through the anode chamber inlet: after energization, the anode chamber becomes an acidic area; the acidity generated by the anode reduces or removes the alkalinity in the water flowing through the anode chamber, and then flows out from the anode chamber outlet. In the cathode chamber, a conductive liquid is used for circulation. This invention targets the alkalinity in the water to be treated, and no scale is precipitated in the anode chamber during the treatment process. However, on the one hand, the diaphragm used is an expensive anion exchange membrane, cation exchange membrane, or bipolar membrane, resulting in high cost; and on the other hand, because the flow is from the anode chamber inlet to the anode chamber outlet, the process is short, and H2O generated on the electrode surface... + The inability to diffuse in time affects the removal of alkalinity.

[0004] CN112340872A discloses a method for improving the alkalinity removal effect in a single-stage reverse osmosis desalination process. This method involves adding an acid addition device upstream of the reverse osmosis unit to remove alkalinity from the water, and then using the interception effect of the reverse osmosis unit to improve the overall alkalinity removal effect. A decarbonator is added downstream of the acid addition device to remove the generated free CO2, as well as dissolved CO2 in the raw water that the reverse osmosis unit cannot remove. This invention requires adding an acid addition device upstream of the reverse osmosis unit for alkalinity removal, which necessitates the introduction of a large amount of acid and increases the salinity of the effluent. Furthermore, the need for a decarbonator downstream of the acid addition device to remove free CO2 makes the process relatively cumbersome. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an electrochemical reaction system and its application. The reaction system provided by this invention can achieve isolation between the anode and cathode chambers and rapid diffusion into the acidic region, exhibiting excellent alkalinity removal performance in wastewater treatment and improving electrode lifespan.

[0006] The present invention provides an electrochemical reaction system, including an electrode assembly and a cathode chamber and an anode chamber separated by the electrode assembly. The electrode assembly mainly includes a cathode, a porous aeration component and an anode, wherein the porous aeration component is disposed between the cathode and the anode and is a mesh structure formed by several aeration pipes interwoven together. An aeration port is provided on the side facing the anode chamber, and the rest is sealed.

[0007] In this invention, the electrode assembly divides the reaction system into a cathode chamber and an anode chamber, wherein the chamber closer to the anode is the anode chamber and the chamber closer to the cathode is the cathode chamber, and the volume ratio of the cathode chamber to the anode chamber is 1:5-1:10.

[0008] In this invention, the cathode, porous aeration component, and anode are arranged in close contact with each other in the electrode assembly, and the electrode spacing is 1.0-10.0 mm.

[0009] In this invention, the anode is any one of the shape-stable anodes such as titanium-based ruthenium-iridium electrode, ruthenium-tantalum electrode, iridium-tantalum electrode, ruthenium-iridium-tantalum electrode, and ruthenium-iridium-tin electrode, with a mesh size of 10-800 mesh, and can be any structural form such as ring, sheet, or column.

[0010] In this invention, the cathode is any one of palladium, titanium, zinc, bismuth, tin, iron, cobalt, aluminum, nickel, platinum, or their alloy electrodes, with a mesh size of 10-800 mesh, and can be any structural form such as ring, sheet, or column.

[0011] In this invention, the porous aeration component can be any structural form such as annular, sheet-like, or columnar, with a thickness of 1.0-10.0 mm, preferably 2.0-8.0 mm, and preferably the same shape as the cathode and anode. The mesh structure can have any mesh size such as rhomboid, square, or circular, with a mesh count of 10 to 800 meshes.

[0012] In this invention, the aeration pipe has a diameter of 1.0-10.0 mm, and several aeration ports are evenly distributed on one side, i.e., the side facing the anode chamber. The aperture of the aeration ports is 1-100 micrometers. The aeration pipe is made of any one of ceramic, rubber, nylon, PVC, etc.

[0013] In this invention, the electrochemical reaction system can be in the form of a cuboid, cylinder, or other reactor shapes. Multiple electrode groups and anode / cathode chambers can be configured as needed, generally in even numbers, preferably 2-8. For example, two parallel electrode groups result in one anode chamber and two cathode chambers; four parallel electrode groups result in two anode chambers and three cathode chambers. Each anode chamber has an inlet at the bottom and an outlet at the top; each cathode chamber also has an outlet at the top.

[0014] The present invention also provides the application of the above-mentioned electrochemical reaction system in the electrochemical removal of alkalinity from wastewater.

[0015] In this invention, wastewater enters the reaction system from the anode chamber, while gas is simultaneously introduced into the porous aeration component for aeration. The H2 produced by the reaction... + Rapid diffusion is used for alkalinity removal, while the generated CO2 is carried out of the reaction system. The wastewater from which alkalinity has been removed is discharged through the upper part of the anode chamber, and the generated alkaline solution is discharged through the upper part of the cathode chamber.

[0016] In the application of this invention, the gas introduced into the porous aeration component can be any one or more of air, nitrogen, argon, oxygen, carbon dioxide, etc., with air being preferred.

[0017] In this invention, the current density is 5-20 mA / cm². 2 The stay time is 30-60 minutes.

[0018] In the application of this invention, the wastewater contains one or more of carbonate ions, bicarbonate ions, hydroxide ions, etc., and the total alkalinity is 100-5000 mg / L.

[0019] In this invention, the pH value of the anode chamber is below 4, preferably 2.0-3.5.

[0020] In this invention, the generated alkaline solution is discharged from the upper part of the cathode chamber and mixed with the effluent from the anode chamber after alkalinity has been removed, so as to maintain the pH of the effluent.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention arranges the cathode, porous aeration component and anode in close contact to form an electrode group, wherein the porous aeration component faces the anode chamber for aeration, which not only realizes the isolation of the anode and cathode chambers and makes full use of the acid produced by the anode to achieve rapid removal of alkalinity; but also, because the acidic area generated on the electrode surface can be rapidly diffused, the purpose of avoiding electrode corrosion during long-term use is achieved.

[0023] (2) The porous aeration component of the present invention can achieve H in the anode region + The rapid diffusion of the gas can also carry the CO2 gas produced by the reaction out of the reaction system as soon as possible, which helps to further improve the alkalinity removal rate.

[0024] (3) The present invention avoids the use of expensive ion membranes, etc., and the cost is relatively low; and avoids the use of acidic reagents in conventional alkalinity removal, and there is no secondary pollution. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the composition and structure of the two-cathode-one-anode reaction system of the present invention;

[0026] Figure 2This is a schematic diagram of the composition and structure of the three-cathode, two-anode reaction system of the present invention;

[0027] Figure 3 This is an enlarged schematic diagram showing the location and specific structure of the porous aeration component. Detailed Implementation

[0028] The technical solution and its effects of the present invention will be further described in detail below through embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0030] In this embodiment, the alkalinity of the wastewater was detected using a volumetric method. Alkalinity removal rate = (influent alkalinity - effluent alkalinity) / influent alkalinity × 100%.

[0031] Example 1

[0032] The electrochemical reaction system adopts an attached Figure 1 The structure shown is a cuboid reactor, comprising two electrode groups and an anode chamber and two cathode chambers separated by the electrode groups. The volume ratio of the cathode chamber to the anode chamber is 1:5. Nickel electrodes are selected as cathodes, and titanium-based ruthenium-iridium electrodes are selected as anodes. Both electrodes have a mesh size of 100 mesh and a thickness of 4.0 mm, and both have a mesh-like sheet structure. The cathode, porous aeration component, and anode are arranged in close proximity, with an electrode spacing of 10 mm. An inlet is located at the bottom of the anode chamber, and a drain is located at the top; a drain is also located at the top of the cathode chamber.

[0033] The porous aeration component is a ceramic mesh made of several aeration tubes interwoven together. It is 4.0 mm thick and has the same shape as the cathode and anode. The ceramic mesh has a rhomboid mesh size of 100 mesh. The aeration tubes have a diameter of 4.0 mm and an aeration port with a pore size of 50 micrometers is provided on the side facing the anode chamber. The rest of the aeration port is sealed.

[0034] The wastewater being treated contains carbonate ions, bicarbonate ions, and hydroxide ions, with an alkalinity of 2000 mg / L.

[0035] The treatment method includes: wastewater entering from the bottom of the anode chamber and exiting from the top of the anode chamber; simultaneously, air is introduced into the porous aeration component for aeration; an acidic zone can be quickly formed in the anode chamber between the two anodes, and the aeration zone is rapidly diffused for alkalinity removal; at the same time, the generated CO2 is carried out of the reaction system. The control conditions are as follows: current density is 10 mA / cm³. 2 The residence time is 60 minutes, and the pH value of the anode chamber is adjusted to about 3.0.

[0036] After the reaction is complete, the alkalinity removal rate can reach 91.6%.

[0037] Example 2

[0038] The electrochemical reaction system adopts an attached Figure 1 The structure shown has a cathode chamber to anode chamber volume ratio of 1:5. Iron electrodes are selected as the cathode, and ruthenium-tantalum electrodes as the anode. Both electrodes have a mesh size of 10 mesh and a thickness of 10.0 mm, and are of a mesh-like or sheet-like structure. The cathode, porous aeration component, and anode are arranged in close proximity, with an electrode spacing of 1.0 mm. An inlet is located at the bottom of the anode chamber, and a drain outlet is located at the top; a drain outlet is also located at the top of the cathode chamber.

[0039] The porous aeration component is a ceramic mesh made of several aeration tubes interwoven together. It is 1.0 mm thick and has the same shape as the cathode and anode. The ceramic mesh has a rhomboid mesh size of 800 mesh. The aeration tubes have a diameter of 1.0 mm and an aeration port with a pore size of 10 micrometers is provided on the side facing the anode chamber. The rest of the aeration port is sealed.

[0040] The treatment method includes: the wastewater being treated is the same as in Example 1, entering from the bottom of the anode chamber and exiting from the top; simultaneously, air is introduced into the porous aeration assembly for aeration; an acidic zone can be quickly formed in the anode chamber between the two anodes, and the anode rapidly diffuses for alkalinity removal; at the same time, the generated CO2 is carried out of the reaction system. The control conditions are as follows: current density is 20 mA / cm³. 2 The residence time is 30 minutes, and the pH value of the anode chamber is adjusted to about 3.5.

[0041] After the reaction is complete, the alkalinity removal rate can reach 85.5%.

[0042] Example 3

[0043] The electrochemical reaction system adopts an attached Figure 1 The structure shown has a cathode chamber to anode chamber volume ratio of 1:10. Titanium electrodes are selected as the cathode, and iridium-tantalum electrodes as the anode. Both electrodes have a mesh size of 800 mesh and a thickness of 1.0 mm, and are of a mesh-like or sheet-like structure. The cathode, porous aeration component, and anode are arranged in close proximity, with an electrode spacing of 10.0 mm. An inlet is located at the bottom of the anode chamber, and a drain outlet is located at the top; a drain outlet is also located at the top of the cathode chamber.

[0044] The porous aeration component is a ceramic mesh made of several aeration tubes interwoven together. It is 10.0 mm thick and has the same shape as the cathode and anode. The ceramic mesh has diamond-shaped openings with a mesh size of 10. The aeration tubes are 10 mm in diameter and have aeration ports on the side facing the anode chamber. The aperture of the aeration ports is 100 micrometers, and the rest is sealed.

[0045] The treatment method includes: the wastewater being treated is the same as in Example 1, entering from the bottom of the anode chamber and exiting from the top; simultaneously, air is introduced into the porous aeration assembly for aeration; an acidic zone can be quickly formed in the anode chamber between the two anodes, and the anode rapidly diffuses for alkalinity removal; at the same time, the generated CO2 is carried out of the reaction system. The control conditions are as follows: current density is 5 mA / cm³. 2 The residence time was 60 minutes, and the pH value of the anode chamber was adjusted to around 3.3.

[0046] After the reaction is complete, the alkalinity removal rate can reach 87.9%.

[0047] Example 4

[0048] Same as Example 1, except that: an appendix is ​​used. Figure 2 The device shown is a three-cathode, two-anode chamber configuration. A portion of the alkaline solution in the cathode chamber can be periodically removed, and the solutions from both chambers are mixed after the reaction to maintain the pH. The porous aeration component is the same as in Example 1. The water treatment capacity is twice that of Example 1.

[0049] The treatment method includes: the wastewater is treated in the same manner as in Example 1, with the wastewater entering from the bottom of the anode chamber and exiting from the top. Simultaneously, air is introduced into the porous aeration assembly for aeration. An acidic zone can quickly form in the anode chamber between the two anodes, and the anode rapidly diffuses for alkalinity removal. The generated CO2 is carried out of the reaction system. The control conditions are as follows: current density is 10 mA / cm³. 2 The residence time is 60 minutes, and the pH value of the anode chamber is adjusted to about 3.0.

[0050] After the reaction is complete, the alkalinity removal rate can reach 91.2%.

[0051] Example 5

[0052] Similar to Example 1, the treatment method includes: the wastewater being treated is the same as in Example 1, entering from the bottom of the anode chamber and exiting from the top; simultaneously, carbon dioxide is introduced into the porous aeration assembly for aeration; an acidic zone can be quickly formed in the anode chamber between the two anodes, and the anode rapidly diffuses for alkalinity removal; the generated CO2 is carried out of the reaction system. The control conditions are as follows: current density is 10 mA / cm². 2 The residence time is 60 minutes, and the pH value of the anode chamber is adjusted to about 3.0.

[0053] After the reaction was completed, the alkalinity removal rate was 84.5%.

[0054] Comparative Example 1

[0055] Same as Example 1, except that the porous aeration component was replaced with a regular PVC mesh, and no aeration was performed. After the reaction, the alkalinity removal rate was 54.9%, which was attributed to the H+ generated during electrolysis.+ The diffusion rate is slow and the carbon dioxide cannot be quickly stripped away, resulting in a decrease in removal efficiency.

[0056] Comparative Example 2

[0057] Same as Example 1, except that the porous aeration component was replaced with an ion exchange membrane, which could not aerate. After the reaction, the alkalinity removal rate was 56.2%. The reason for this was due to the H+ generated during electrolysis. + The diffusion rate is slow and the carbon dioxide cannot be quickly stripped away, resulting in a decrease in removal efficiency.

[0058] Comparative Example 3

[0059] Similar to Example 1, but with the difference that the porous aeration component provides bidirectional aeration. After the reaction, the alkalinity removal rate was 84.7%. This indicates that simultaneous aeration of the cathode and anode chambers does not actually improve the alkalinity removal rate.

[0060] Comparative Example 4

[0061] Similar to Example 1, except that a porous aeration component was not used. After the reaction, the alkalinity removal rate was only 6.4%. This is because the porous aeration component was not used; due to the small electrode spacing, the H₂ generated at the anode... + and OH - The two react with each other, and the pH of the solution remains essentially unchanged.

Claims

1. An electrochemical reaction system, characterized in that... It includes an electrode assembly and a cathode chamber and an anode chamber separated by the electrode assembly. The electrode assembly mainly includes a cathode, a porous aeration component and an anode. The porous aeration component is located between the cathode and the anode and is a mesh structure made up of several aeration pipes. It has an aeration port on the side facing the anode chamber and the rest is sealed.

2. The system according to claim 1, characterized in that: The electrode assembly divides the reaction system into a cathode chamber and an anode chamber, with the chamber closer to the anode being the anode chamber and the chamber closer to the cathode being the cathode chamber. The volume ratio of the cathode chamber to the anode chamber is 1:5 to 1:

10.

3. The system according to claim 1, characterized in that: In the electrode assembly, the cathode, porous aeration component, and anode are arranged in close contact, with an electrode spacing of 1.0-10.0 mm.

4. The system according to claim 1, characterized in that: The anode is any one of the following: titanium-based ruthenium-iridium electrode, ruthenium-tantalum electrode, iridium-tantalum electrode, ruthenium-iridium-tantalum electrode, and ruthenium-iridium-tin electrode. The mesh size is 10-800 mesh, and the anode can be any one of the following structural forms: ring-shaped, sheet-shaped, or columnar.

5. The system according to claim 1, characterized in that: The cathode is any one of palladium, titanium, zinc, bismuth, tin, iron, cobalt, aluminum, nickel, platinum, or their alloy electrodes, with a mesh size of 10-800 mesh, and can be any one of the following structural forms: ring, sheet, or column.

6. The system according to claim 1, characterized in that: The porous aeration component can be any of the following structural forms: annular, sheet-like, or columnar, with a thickness of 1.0-10.0 mm.

7. The system according to claim 6, characterized in that: The porous aeration components have a thickness of 2.0-8.0 mm and the same shape as the cathode and anode.

8. The system according to claim 1, characterized in that: The mesh structure has any one of rhomboid, square, or circular openings, with a mesh count ranging from 10 to 800 meshes.

9. The system according to claim 1, characterized in that: The aeration pipe has a diameter of 1.0-10.0 mm, and several aeration ports are evenly distributed on one side, i.e., the side facing the anode chamber. The aperture of the aeration port is 1-100 micrometers. The aeration pipe is made of any one of ceramic, rubber, nylon, or PVC.

10. The system according to claim 1, characterized in that: The electrochemical reaction system is in the form of a cuboid or cylindrical reactor; multiple electrode groups and anode / cathode chambers are set according to requirements, with an even number of sets.

11. The system according to claim 10, characterized in that: The quantity can be set to 2-8.

12. The system according to claim 1, characterized in that: Each anode chamber has a water inlet at the bottom and a drain outlet at the top; each cathode chamber has a drain outlet at the top.

13. The application of the electrochemical reaction system according to any one of claims 1-12 in the electrochemical removal of alkalinity from wastewater.

14. The application according to claim 13, characterized in that: Wastewater enters the reaction system from the anode chamber, while gas is simultaneously introduced into the porous aeration components for aeration. The H2 produced by the reaction... + Rapid diffusion is used for alkalinity removal, while the generated CO2 is carried out of the reaction system. The wastewater from which alkalinity has been removed is discharged through the upper part of the anode chamber, and the generated alkaline solution is discharged through the upper part of the cathode chamber.

15. The application according to claim 13, characterized in that: The gas introduced into the porous aeration component is any one or more of air, nitrogen, argon, oxygen, and carbon dioxide.

16. The application according to claim 15, characterized in that: The gas introduced into the porous aeration component is air.

17. The application according to claim 13 or 14, characterized in that: Current density is 5-20 mA / cm 2 The stay time is 30-60 minutes.

18. The application according to claim 13 or 14, characterized in that: The wastewater contains one or more of the following: carbonate ions, bicarbonate ions, and hydroxide ions, with a total alkalinity of 100-5000 mg / L.

19. The application according to claim 13 or 14, characterized in that: The pH value of the anode chamber is below 4.

20. The application according to claim 19, characterized in that: The pH value of the anode chamber is 2.0-3.5.

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