Electrochemical reaction system and application thereof

Abstract

The invention relates to an electrochemical reaction system and application thereof.The electrochemical reaction system comprises an electrode set, a cathode chamber and an anode chamber, the cathode chamber and the anode chamber are separated by the electrode set, the electrode set mainly comprises a cathode, a porous aeration assembly and an anode, the porous aeration assembly is arranged between the cathode and the anode and is of a net-shaped structure formed by interweaving a plurality of aeration pipes, and the aeration pipes are arranged in the net-shaped structure. An aeration opening is formed in one side facing the anode chamber, and the other parts are sealed. The reaction system provided by the invention can realize isolation of the cathode chamber and the anode chamber and rapid diffusion of an acidic region, has excellent removal performance when being used for removing alkalinity of wastewater, and can prolong the service life of the electrode.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to an electrochemical reaction system and application thereof. Background Art

[0002] Electrochemical technology is favored by more and more researchers due to its advantages such as environmental friendliness, easy operation and no secondary pollution. It can be widely used in pollutant removal by utilizing the redox characteristics of the anode and cathode, including common electrochemical degradation of organic matter, electrochemical reduction removal of nitrates, electrochemical descaling, etc. In addition, it is also widely used in electrochemical enhanced biochemical processes, electrochemical production of hydrogen peroxide, electrochemical production of acids and alkalis, etc.

[0003] CN106277369A discloses an electrochemical scale inhibition method, including: 1) dividing the electrolytic cell into an anode chamber and a cathode chamber by a diaphragm, and placing the anode and the cathode in the anode chamber and the cathode chamber respectively; 2) allowing the water to be treated to flow through the anode chamber through the anode chamber inlet: after power is turned on, the anode chamber becomes an acidic area; the acidity generated by the anode is used to reduce or remove the alkalinity in the water flowing through the anode chamber, and then it flows out from the anode chamber outlet, and in the cathode chamber, a conductive liquid is used for circulation. This invention is aimed at treating 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, a cation exchange membrane or a bipolar membrane, which has a high cost; and because it enters and exits the anode chamber, the process is short, and the H generated on the electrode surface + It cannot diffuse in time, affecting the alkalinity removal effect.

[0004] CN112340872A discloses a method for improving the alkalinity removal effect of a single-stage reverse osmosis desalination process, which is to add an acid adding device at the front end of the reverse osmosis device to remove the alkalinity in the water, and then improve the alkalinity removal effect as a whole through the interception effect of the reverse osmosis device; add a decarbonizer at the rear end of the acid adding device to remove the generated free CO2, and at the same time remove the CO2 dissolved in the raw water that the reverse osmosis device cannot remove. This invention is to add an acid adding device at the front end of the reverse osmosis device for alkalinity removal, which requires the introduction of a large amount of acid to remove the alkalinity, and will cause the salinity of the effluent water to increase. In addition, a decarbonizer needs to be added at the rear end of the acid adding device to remove free CO2, and the process is also relatively cumbersome. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides an electrochemical reaction system and its application. The reaction system provided by the present invention can achieve the isolation of the anode and cathode chambers and the rapid diffusion of the acidic region, has excellent removal performance when used for removing alkalinity from wastewater, and can increase the service life of the electrode.

[0006] One aspect of the present invention provides an electrochemical reaction system, comprising an electrode group and a cathode chamber and an anode chamber separated by the electrode group, wherein the electrode group mainly comprises a cathode, a porous aeration component and an anode, wherein the porous aeration component is arranged between the cathode and the anode, and is a mesh structure formed by interweaving a plurality of aeration tubes, an aeration port is arranged on the side facing the anode chamber, and the rest of the parts are sealed.

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

[0008] In the present invention, in the electrode group, the cathode, the porous aeration assembly and the anode are arranged closely, and the electrode spacing is 1.0-10.0 mm.

[0009] In the present 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, ruthenium-iridium-tin electrode, etc., with a mesh size of 10-800 meshes, and can be any structural form such as ring, sheet, columnar, etc.

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

[0011] In the present invention, the porous aeration component can be in any structural form such as ring, sheet, column, etc., with a thickness of 1.0-10.0 mm, preferably 2.0-8.0 mm, and preferably the same shape as the cathode and the anode. The mesh of the mesh structure can be in any one of diamond, square, circle, etc., with a mesh size of 10 to 800 meshes.

[0012] In the present invention, the diameter of the aeration pipe is 1.0-10.0 mm, and a plurality of aeration ports are evenly distributed on one side, that is, toward the anode chamber, and the aperture of the aeration ports is 1-100 microns. The material of the aeration pipe is any one of ceramic, rubber, nylon, PVC, etc.

[0013] In the present invention, the electrochemical reaction system can be in the form of a reactor such as a cuboid or a cylinder. Multiple electrode groups and anode and cathode chambers can be set according to needs. The number of electrode groups is generally an even number, preferably 2-8. For example, when two parallel electrode groups are set, there is one anode chamber and two cathode chambers, and when four parallel electrode groups are set, there are two anode chambers and three cathode chambers. A water inlet is provided at the bottom of each anode chamber, and a drain outlet is provided at the top; a drain outlet is provided at the top of each cathode chamber.

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

[0015] In the application of the present invention, wastewater enters the reaction system from the anode chamber, and gas is introduced into the porous aeration component for aeration. The H + It diffuses rapidly and is used to remove alkalinity. At the same time, the CO2 produced is carried out of the reaction system. The wastewater with alkalinity removed is discharged through the upper part of the anode chamber, and the alkaline solution produced is discharged through the upper part of the cathode chamber.

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

[0017] In the application of the present invention, the current density is 5-20 mA / cm 2 , the residence time is 30-60min.

[0018] In the application of the present 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 the application of the present invention, the pH value of the anode chamber is lower than 4, preferably 2.0-3.5.

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

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

[0022] (1) The present invention places the cathode, porous aeration assembly and anode in close proximity to form an electrode group, wherein the porous aeration assembly aerates toward the anode chamber, which not only achieves isolation between the anode and cathode chambers and fully utilizes the acid produced by the anode to achieve rapid removal of alkalinity; but also because the acidic area produced on the electrode surface can be quickly diffused, the purpose of avoiding electrode corrosion during long-term use is achieved.

[0023] (2) The porous aeration assembly of the present invention can achieve H + It can diffuse rapidly and carry the CO2 gas produced by the reaction out of the reaction system as quickly as possible, which helps to further increase the alkalinity removal rate.

[0024] (3) The present invention avoids the use of expensive ion membranes and the like, and has a relatively low cost; it also avoids the use of acidic reagents in conventional alkalinity removal, and has no secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0028] The technical solution of the present invention and its effects are further described in detail below through examples. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

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

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

[0031] Example 1

[0032] The electrochemical reaction system uses Figure 1 The structure shown is a rectangular reactor, including 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. A nickel electrode is selected as the cathode and a titanium-based ruthenium-iridium electrode is selected as the anode. The mesh number is 100 meshes, the thickness is 4.0 mm, and both are mesh sheet structures. The cathode, porous aeration assembly and anode are closely arranged, and the electrode spacing is 10 mm. A water inlet is provided at the bottom of the anode chamber, and a drain is provided at the top; a drain is provided at the top of the cathode chamber.

[0033] The porous aeration component is a ceramic mesh interwoven by several aeration tubes, with a thickness of 4.0 mm and the same shape as the cathode and anode. The mesh of the ceramic mesh is diamond-shaped and the mesh number is 100. The diameter of the aeration tube is 4.0 mm, and an aeration port is provided on the side facing the anode chamber. The aperture of the aeration port is 50 microns, and the rest is sealed.

[0034] The treated wastewater contains carbonate ions, bicarbonate ions, and hydroxide ions, and the alkalinity is 2000 mg / L.

[0035] The treatment method includes: wastewater enters from the bottom of the anode chamber and exits from the top of the anode chamber, and air is introduced into the porous aeration assembly for aeration. The anode chamber between the two anodes can quickly form an acidic area and diffuse quickly for alkalinity removal. At the same time, the generated CO2 is carried out of the reaction system. The control conditions are as follows: the current density is 10mA / cm 2 , the residence time is 60min, and the pH value of the anode chamber is regulated to about 3.0.

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

[0037] Example 2

[0038] The electrochemical reaction system uses Figure 1 In the structure shown, the volume ratio of the cathode chamber to the anode chamber is 1:5, the iron electrode is selected as the cathode, and the ruthenium-tantalum electrode is selected as the anode. The mesh number is 10 meshes, the thickness is 10.0 mm, and both are mesh sheet structures. The cathode, porous aeration assembly and anode are closely arranged, and the electrode spacing is 1.0 mm. A water inlet is provided at the bottom of the anode chamber, and a drain is provided at the top; a drain is provided at the top of the cathode chamber.

[0039] The porous aeration component is a ceramic mesh interwoven by several aeration tubes, with a thickness of 1.0 mm and the same shape as the cathode and anode. The mesh of the ceramic mesh is diamond-shaped and the mesh number is 800. The diameter of the aeration tube is 1.0 mm, and an aeration port is provided on the side facing the anode chamber. The aperture of the aeration port is 10 microns, and the rest is sealed.

[0040] The treatment method includes: the treated wastewater is the same as in Example 1, entering from the bottom of the anode chamber and exiting from the top of the anode chamber, and air is introduced into the porous aeration assembly for aeration, so that the anode chamber between the two anodes can quickly form an acidic area, which is quickly diffused for alkalinity removal, and the generated CO2 is carried out of the reaction system. The control conditions are as follows: the current density is 20mA / cm 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 completed, the alkalinity removal rate can reach 85.5%.

[0042] Example 3

[0043] The electrochemical reaction system uses Figure 1 In the structure shown, the volume ratio of the cathode chamber to the anode chamber is 1:10. A titanium electrode is selected as the cathode and an iridium-tantalum electrode is selected as the anode. The mesh number is 800 meshes, the thickness is 1.0 mm, and both are mesh-like sheet structures. The cathode, porous aeration assembly and anode are closely arranged, and the electrode spacing is 10.0 mm. A water inlet is provided at the bottom of the anode chamber, and a drain is provided at the top; a drain is provided at the top of the cathode chamber.

[0044] The porous aeration component is a ceramic mesh interwoven by several aeration tubes, with a thickness of 10.0 mm and the same shape as the cathode and anode. The mesh of the ceramic mesh is diamond-shaped and the mesh number is 10. The diameter of the aeration tube is 10 mm, and an aeration port is provided on the side facing the anode chamber. The aperture of the aeration port is 100 microns, and the rest is sealed.

[0045] The treatment method includes: the treated wastewater is the same as that in Example 1, entering from the bottom of the anode chamber and exiting from the top of the anode chamber, and air is introduced into the porous aeration assembly for aeration, so that the anode chamber between the two anodes can quickly form an acidic area, which is quickly diffused for alkalinity removal, and the generated CO2 is carried out of the reaction system. The control conditions are as follows: the current density is 5mA / cm 2 , the residence time is 60min, and the pH value of the anode chamber is regulated to about 3.3.

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

[0047] Example 4

[0048] Same as Example 1, except that: Figure 2 The device shown is in the form of three cathode and two anode chambers. Part of the alkaline solution in the cathode chamber can be taken out regularly. After the reaction is completed, the solutions in the two chambers are mixed to maintain the pH. The porous aeration component is the same as in Example 1. The amount of water treated is twice that of Example 1.

[0049] The treatment method includes: the treated wastewater is the same as that in Example 1, the wastewater enters from the bottom of the anode chamber and exits from the top of the anode chamber, and air is introduced into the porous aeration assembly for aeration, the anode chamber between the two anodes can quickly form an acidic area, and quickly diffuse for alkalinity removal, and the generated CO2 is carried out of the reaction system. The control conditions are as follows: the current density is 10mA / cm 2 , the residence time is 60min, and the pH value of the anode chamber is regulated to about 3.0.

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

[0051] Example 5

[0052] The same as in Example 1, the treatment method includes: the treated wastewater is the same as in Example 1, the wastewater enters from the bottom of the anode chamber and exits from the top of the anode chamber, and carbon dioxide is introduced into the porous aeration assembly for aeration, the anode chamber between the two anodes can quickly form an acidic area, and quickly diffuse for alkalinity removal, and the generated CO2 is carried out of the reaction system. The control conditions are as follows: the current density is 10mA / cm 2 , the residence time is 60min, and the pH value of the anode chamber is regulated 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 assembly was replaced with a common PVC screen and no aeration was performed. After the reaction was completed, the alkalinity removal rate was 54.9%. The reason for this was that the H generated by electrolysis+ The diffusion rate is slow, and the carbon dioxide cannot be blown off quickly, resulting in a decrease in the removal effect.

[0056] Comparative Example 2

[0057] Same as Example 1, except that the porous aeration assembly was replaced with an ion membrane and aeration was not possible. After the reaction was completed, the alkalinity removal rate was 56.2%. The reason for this was that the H generated by electrolysis + The diffusion rate is slow, and the carbon dioxide cannot be blown off quickly, resulting in a decrease in the removal effect.

[0058] Comparative Example 3

[0059] Same as Example 1, except that the porous aeration assembly is bidirectionally aerated. After the reaction is completed, the alkalinity removal rate is 84.7%. It can be seen that aerating the cathode chamber and the anode chamber at the same time cannot improve the alkalinity removal rate.

[0060] Comparative Example 4

[0061] The same as Example 1, except that no porous aeration assembly was provided. After the reaction was completed, the alkalinity removal rate was only 6.4%. The reason was that no porous aeration assembly was provided, and the H generated at the anode was too small due to the small electrode spacing. + and OH - The pH of the solution remains basically unchanged.

Claims

1. An electrochemical reaction system, characterized in that It includes an electrode group and a cathode chamber and an anode chamber separated by the electrode group. The electrode group mainly includes a cathode, a porous aeration component and an anode. The porous aeration component is arranged between the cathode and the anode. It is a mesh structure formed by interweaving a plurality of aeration tubes. An aeration port is arranged on the side facing the anode chamber, and the rest of the parts are sealed.

2. The system according to claim 1, characterized in that: The electrode group divides the reaction system into a cathode chamber and an anode chamber, wherein the anode chamber is close to the anode and the cathode chamber is close to the cathode, and the volume ratio of the cathode chamber to the anode chamber is 1:5-1:

10.

3. The system according to claim 1, characterized in that: In the electrode group, the cathode, the porous aeration assembly and the anode are arranged closely, and the electrode spacing is 1.0-10.0 mm.

4. The system according to claim 1, characterized in that: The anode is any one of titanium-based ruthenium-iridium electrode, ruthenium-tantalum electrode, iridium-tantalum electrode, ruthenium-iridium-tantalum electrode, and ruthenium-iridium-tin electrode shape-stable anode, with a mesh size of 10-800 meshes and any one of annular, sheet, and columnar structural forms.

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 single electrode or their alloy electrodes, with a mesh size of 10-800 meshes and any one of ring, sheet or columnar structural forms.

6. The system according to claim 1, characterized in that: The porous aeration component is in any of the structural forms of annular, sheet-like or columnar, with a thickness of 1.0-10.0 mm, preferably 2.0-8.0 mm, and preferably has the same shape as the cathode and the anode.

7. The system according to claim 1, characterized in that: The meshes of the mesh structure are any one of diamond, square and circle, and the mesh number is 10 to 800.

8. The system according to claim 1, characterized in that: The diameter of the aeration pipe is 1.0-10.0 mm, and a plurality of aeration ports are evenly distributed on one side, that is, toward the anode chamber, and the aperture of the aeration ports is 1-100 microns; the material of the aeration pipe is any one of ceramic, rubber, nylon, and PVC.

9. The system according to claim 1, characterized in that: The electrochemical reaction system is in the form of a rectangular parallelepiped or cylindrical reactor; multiple electrode groups and anode and cathode chambers are arranged according to needs, and the number of the arranged groups is generally an even number, preferably 2-8.

10. The system according to claim 1, characterized in that: A water inlet is provided at the bottom of each anode chamber, and a drain outlet is provided at the top; a drain outlet is provided at the top of each cathode chamber.

11. Use of the electrochemical reaction system according to any one of claims 1 to 10 in electrochemical removal of alkalinity from wastewater.

12. The use according to claim 11, characterized in that: Wastewater enters the reaction system from the anode chamber, and gas is introduced into the porous aeration component for aeration. The H + It diffuses rapidly and is used to remove alkalinity. At the same time, the CO2 produced is carried out of the reaction system. The wastewater with alkalinity removed is discharged through the upper part of the anode chamber, and the alkaline solution produced is discharged through the upper part of the cathode chamber.

13. The use according to claim 12, characterized in that: The gas introduced into the porous aeration component is any one or more of air, nitrogen, argon, oxygen and carbon dioxide, preferably air.

14. The use according to claim 11 or 12, characterized in that: Current density is 5-20 mA / cm 2 , the residence time is 30-60 min.

15. The use according to claim 11 or 12, characterized in that: The wastewater contains one or more of carbonate ions, bicarbonate ions and hydroxide ions, and the total alkalinity is 100-5000 mg / L.

16. The use according to claim 11 or 12, characterized in that: The pH value of the anode chamber is lower than 4, preferably 2.0-3.5.

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