Cathode plate, electro-catalytic oxidation device and manufacturing method of cathode plate

Abstract

The present application relates to the field of electrocatalytic wastewater treatment, and discloses a cathode plate, an electrocatalytic oxidation device and a manufacturing method of the cathode plate, the cathode plate comprising metal mesh and biomass charcoal layers which are alternately stacked, and the biomass charcoal layers are distributed at least in the outer layer of the stack to coat the stacked surface of the metal mesh. The cathode plate in the present application can be used as a cathode to construct an electrocatalytic degradation system, and the surface of the cathode plate has a multi-level pore structure and abundant oxygen-containing functional groups, which can generate a large amount of H2O2 on the electrode surface, effectively inhibit the cathode pollution phenomenon, prevent fouling, and the generated H2O2 can catalyze the generation of hydroxyl radicals on the anode surface, thereby further promoting the degradation of pollutants and achieving the full use of electric energy in the degradation system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electro-catalytic wastewater treatment, in particular to a cathode plate, an electro-catalytic oxidation device and a manufacturing method of the cathode plate. BACKGROUND

[0002] As a new type of chemical treatment technology, electro-catalysis has the advantages of high mineralization rate and fast degradation rate in removing refractory organic pollutants. However, in the actual application at the present stage, the anode in the electro-catalytic device is generally used to catalytically oxidize pollutants to achieve the purpose of removing pollutants. The cathode in the device is generally made of stainless steel or titanium, and the surface of the cathode is easy to scale during the reaction, thereby affecting the catalytic efficiency and increasing the operating cost. Most importantly, the cathode in the electro-catalytic device is not fully utilized, resulting in waste of energy. SUMMARY

[0003] The purpose of the present application is to overcome the problems of easy scaling of the cathode in the electro-catalytic device and no catalytic effect on the degradation system in the prior art, and to provide a cathode plate, an electro-catalytic oxidation device and a manufacturing method of the cathode plate. The cathode plate can be used as a cathode to construct an electro-catalytic degradation system, and the surface of the cathode plate has a multi-level pore structure and abundant oxygen-containing functional groups, which can generate a large amount of H2O2 on the electrode surface, effectively inhibit the cathode pollution phenomenon to prevent scaling, and the generated H2O2 can catalytically generate hydroxyl radicals on the anode surface, thereby further promoting the degradation of pollutants and achieving full utilization of electrical energy in the degradation system.

[0004] To achieve the above purpose, the first aspect of the present application provides a cathode plate comprising alternating layers of metal mesh and biomass charcoal layer, wherein the biomass charcoal layer is distributed at least in the outer layer to cover the layered surface of the metal mesh.

[0005] Optionally, the cathode plate comprises three biomass charcoal layers distributed in the outer layer and two metal meshes arranged between the three biomass charcoal layers.

[0006] Optionally, the number of holes of the metal mesh is 10-100 mesh, and the thickness is 1-3 mm.

[0007] Optionally, the metal mesh is a titanium metal mesh.

[0008] Optionally, the biomass charcoal layer is a wood charcoal layer, and the thickness is 10-30 mm.

[0009] The second aspect of the present application provides an electro-catalytic oxidation device comprising a power supply, an anode plate connected to the power supply, and a cathode plate connected to the power supply.

[0010] Optionally, the anode plate material is a ruthenium-iridium alloy, with a length of 90-110 mm, a width of 70-90 mm, and a thickness of 8-12 mm.

[0011] Optionally, the length of the cathode plate is 90-110 mm, and the width is 70-90 mm; wherein the thickness of the compressed cathode plate is 10-30 mm.

[0012] Optionally, the length of the metal mesh in the cathode plate is 90-100 mm, the width is 70-80 mm, the thickness is 1-3 mm, and the number of holes is 10-100 mesh.

[0013] Optionally, the length of the wood charcoal layer in the cathode plate is 90-110 mm, the width is 70-90 mm, and the thickness is 10-30 mm.

[0014] The third aspect of the present application provides a method for manufacturing a cathode plate:

[0015] S1: soaking the wooden material in an alkaline solution;

[0016] S2: rinsing the wooden material soaked in the alkaline solution with deionized water, and then soaking it in an acidic solution to make the pH value of the wooden material 7, and finally storing it in deionized water;

[0017] S3: stacking the wooden material stored in deionized water and the metal mesh at a distance from each other to form a composite material, and compressing the composite material;

[0018] S4: high-temperature reaction of the compressed composite material, natural cooling, rinsing with deionized water until the water pH is 7, and then drying at 60°C.

[0019] Optionally, in step S1, the wooden material is oak, fir, elm, birch, and nanmu.

[0020] Optionally, in step S1, the temperature is room temperature, the alkaline solution is 2-4 mol / L NaOH or KOH, the soaking time is 24-48 h, and the soaking process is continuously stirred.

[0021] Optionally, in step S2, the temperature is room temperature, the acidic solution is 0.5 mol / L HCl, the soaking time is 12 h, and the soaking process is continuously stirred.

[0022] Optionally, in step S3, the stacked composite material is compressed using a tablet press.

[0023] Optionally, in step S4: the compressed composite material is placed in an oven until it is completely dry, and then it is placed in a tube furnace.

[0024] S41: the tube furnace is heated to 350 DEG C at a heating rate of 5 DEG C / min, and maintained for 1h;

[0025] S42: the tube furnace is heated to 700-800 DEG C at a heating rate of 5 DEG C / min, and maintained for 20-30min;

[0026] Wherein, N2 is continuously filled in the process of high-temperature reaction.

[0027] Through the above technical solution, the beneficial effects of the present application are as follows:

[0028] In the process of electro-catalytic oxidation, the surface of the biomass charcoal layer has a large number of microporous structures, so that the available surface area is larger, and the surface of the biomass charcoal layer contains a large number of heteroatoms, which can promote the catalytic reaction; wherein, a large number of oxygen-containing functional groups (such as carboxyl, hydroxyl, ether bond, etc.) remaining on the surface of the biomass charcoal layer can be used as active sites for electro-catalytic oxidation reaction, which can synergistically strengthen the production of hydrogen peroxide by cathode electro-catalysis, effectively inhibit the pollution of the electrode surface, and improve the electro-catalytic degradation and mineralization efficiency. The metal mesh can enhance the mechanical strength of the biomass charcoal layer, and is also beneficial to increase the surface of the biomass charcoal layer having a large number of microporous structures. The cathode plate solves the problems of cathode fouling pollution, low catalytic efficiency, high investment and operation cost.

[0029] Other features and advantages of the present application will be described in detail in the following specific embodiments.

[0030] In the drawings:

[0031] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and together with the following specific embodiments, serve to explain the present application, but do not constitute a limitation on the present application. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic diagram of one embodiment of the cathode plate in the present application;

[0033] Figure 2 is a schematic diagram of one embodiment of the electro-catalytic oxidation device in the present application.

[0034] Explanation of reference signs

[0035] 1-electro-catalytic oxidation device, 2-anode plate, 3-cathode plate, 4-biomass charcoal layer, 5-metal mesh, 6-power supply. DETAILED DESCRIPTION

[0036] The specific embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0037] As Figure 1 shown, the cathode plate 3 in the application includes metal mesh 5 and biomass charcoal layer 4 which are alternately stacked, and the biomass charcoal layer 4 is distributed at least in the outer layer to cover the stacked surface of the metal mesh 5; the biomass charcoal layer 4 completely covers the metal mesh 5 to avoid oxidation of the metal mesh 5 and thus damage.

[0038] The surface of the biomass charcoal layer 4 has a large number of microporous structures, so that the available surface area is larger, and the surface of the biomass charcoal layer 4 contains a large number of heteroatoms, which can promote the progress of catalytic reaction. A large number of oxygen-containing functional groups such as carboxyl, hydroxyl and ether bond remaining on the surface of the biomass charcoal layer 4 can be used as active sites for electrocatalytic oxidation reaction, which can synergistically strengthen the production of hydrogen peroxide by cathode electrocatalysis, effectively inhibit the pollution of the electrode surface, and improve the electrocatalytic degradation and mineralization efficiency. The material of the biomass charcoal layer 4 is not limited in type, for example, oak, fir, elm, birch and nanmu, but the biomass charcoal layer 4 in the application is preferably pine, which is low in cost and easy to obtain; the thickness of the cathode plate 3 can be increased or decreased according to the actual demand to realize the controllable thickness and mechanical properties of the cathode, and the thickness of the biomass charcoal layer 4 is preferably 10-30mm.

[0039] The metal mesh 5 can enhance the mechanical strength of the biomass charcoal layer 4 and is also beneficial to increase the microporous structure on the surface of the biomass charcoal layer 4; the metal mesh 5 can be selected from titanium mesh, stainless steel and iron mesh, etc. The metal mesh 5 in the application is preferably titanium mesh; the number of holes of the metal mesh 5 is 10-100 mesh, and the thickness is 1-3mm.

[0040] The cathode plate 3 in the application preferably includes three biomass charcoal layers 4 distributed in the outer layer and two metal meshes 5 arranged between the three biomass charcoal layers 4.

[0041] As Figure 2 shown, the electrocatalytic oxidation device 1 includes a power supply 6, an anode plate 2 connected to the power supply 6, and a cathode plate 3 connected to the power supply 6. In the process of electrocatalytic oxidation, the hydrogen peroxide produced by the cathode plate 3 can not only inhibit the scaling on the surface of the electrode plate, i.e., improve the anti-pollution ability of the cathode plate 3 and ensure the cleanliness of the cathode plate 3, but also diffuse to the surface of the anode to generate hydroxyl radicals through catalytic reaction, which can further improve the degradation performance of electrocatalysis, i.e., in the degradation process of the electrocatalytic oxidation device 1, the excess hydrogen peroxide produced by the cathode plate 3 reaches the surface of the anode through diffusion and occurs catalytic reaction to generate hydroxyl radicals, thereby further promoting the degradation performance of the electrocatalytic oxidation device 1 as a whole.

[0042] The electro-catalytic oxidation device 1 of the present application can reduce the TOC concentration of high-salt and hard-degradable organic wastewater from 1000 ppm to below 100 ppm, which is significantly improved compared with the electro-catalytic oxidation device 1 with ordinary titanium or stainless steel metal plate 5 as the cathode, which can only degrade to 200 ppm; at the same time, the surface of the cathode of the electro-catalytic oxidation device 1 in the present application is always clean after 24 hours of continuous operation, and there is no obvious pollution; the cathode plate 3 in the present application can solve the problems of cathode fouling pollution, low catalytic efficiency and high investment and operation cost.

[0043] The material selection range of the electro-catalytic oxidation device 1 is as follows:

[0044] The anode plate material is ruthenium-iridium alloy, the length is 90-110 mm, the width is 70-90 mm, and the thickness is 8-12 mm.

[0045] The length of the cathode plate is 90-110 mm, and the width is 70-90 mm; wherein the thickness of the compressed cathode plate is 10-30 mm.

[0046] The length of the metal mesh in the cathode plate is 90-100 mm, the width is 70-80 mm, the thickness is 1-3 mm, and the number of holes is 10-100 mesh.

[0047] The length of the wood charcoal layer in the cathode plate is 90-110 mm, the width is 70-90 mm, and the thickness is 10-30 mm.

[0048] The material of the anode plate 2 in the present application is preferably ruthenium-iridium alloy, but is not limited to ruthenium-iridium alloy electrode material, and the size of the anode plate 2 is preferably: the length is 100 mm, the width is 80 mm, and the thickness is 10 mm.

[0049] The size of the cathode plate 3 in the present application is preferably: the length is 100 mm, the width is 80 mm, and the thickness of the compressed cathode plate 3 is 20 mm.

[0050] The size of the metal mesh 5 of the cathode plate 3 in the present application is preferably: the length is 95 mm, the width is 75 mm, the thickness is 2 mm, and the number of holes is 60 mesh.

[0051] The size of the wood charcoal layer of the cathode plate 3 in the present application is preferably: the length is 100 mm, the width is 80 mm, and the thickness is 20 mm.

[0052] In the present application, the manufacturing method of the cathode plate 3 is:

[0053] In the step S1:

[0054] S11: Select a wood board with a thickness of 10-30 mm, immerse the wood board in a 2-4 mol / L NaOH or KOH aqueous solution at room temperature, immerse for 24-48 h and continuously stir;

[0055] S12: Take out the wood board and rinse with deionized water.

[0056] In the step of S2:

[0057] S21: Put the pretreated wood board in S12 into a 0.5 mol / L HCl aqueous solution at room temperature, continuously stir for 12 h to remove residual alkaline substances;

[0058] S22: Take out the wood board and store it in deionized water for later use.

[0059] In the step of S3:

[0060] S31: Select a metal mesh with the same length and width as the wood board, with a mesh number of 10-100 mesh, and a thickness of 1-3 mm;

[0061] S32: Take out the wood board stored in deionized water and stack it with the metal mesh, as shown in Figure 1 , the outer two sides are pretreated wood boards, and a sandwich structure is constructed, and then the stacked composite material is compressed to a thickness of 10-30 mm using a tablet press.

[0062] In the step of S4:

[0063] S41: Dry the compressed composite material in an oven to ensure complete drying;

[0064] S42: Put the completely dried composite material into a tube furnace for high temperature reaction, wherein the tube furnace is gradiently heated:

[0065] S421: The tube furnace is heated to 350°C at a rate of 5°C / min, and maintained for 1 h;

[0066] S422: The tube furnace is heated to 700-800°C at a rate of 5°C / min, and reacted for 20-30 min;

[0067] S43: Take out the composite material and wash it with deionized water until the water pH is 7, then dry it at 60°C to obtain a biomass charcoal electrode material.

[0068] In the present application, the lignin and hemicellulose in the structure of the wood material can be effectively removed by the process of washing the wood material with alkali, and the cellulose constituting the framework structure is left to form a rich three-dimensional interpenetrating network structure, providing a structural basis for subsequent mechanical compression and carbonization reconstruction. The rigidity of the wood material after alkali washing pretreatment is reduced. In order to enhance the mechanical strength of the wood material, a metal mesh with high conductivity and rigidity is introduced, and the wood material and the metal mesh are stacked in a sandwich structure. After mechanical compression, the softened material after alkali washing is embedded in the space of the metal mesh, and the wood boards on both sides of the metal can fully contact, which helps the carbonization reconstruction of cellulose and the formation of stable covalent bonds in the subsequent calcination process, so as to realize the stable embedding of the metal mesh in the biomass carbon electrode, increase the tensile strength and bending strength of the electrode material, and achieve the purpose of increasing the toughness of the biomass carbon electrode. The acid washing is to neutralize the alkaline substances remaining in the biomass material after alkali washing, so as to prevent the alkaline substances from affecting the high-temperature carbonization reconstruction process of the biomass material during calcination. The stacked and compressed composite material after drying is placed in a tube furnace, and the temperature gradient inside and outside the material is utilized to form a multi-level porous structure based on the original framework structure through the carbonization reconstruction of cellulose, which can effectively strengthen the process of electrocatalytic production of H2O2 by the biomass carbon material. During the high-temperature calcination process, nitrogen is filled to protect the composite material from oxidation and to inhibit the intense reaction process of the biomass material at high temperature to a certain extent. At the same time, incomplete carbonization can form a large number of oxygen-containing functional groups such as carboxyl, hydroxyl and ether bond on the surface of the material, which is beneficial to the adsorption of hydrogen ions and oxygen molecules and the desorption of H2O2 in the catalytic reaction process, and further promotes the progress of the catalytic reaction.

[0069] In the present application, the preferred preparation method of the biomass carbon cathode is as follows:

[0070] Material selection:

[0071] Pine board, thickness 20mm, length 100mm, width 80mm;

[0072] Titanium metal mesh, thickness 2mm, length 100mm, width 80mm, hole number 60 mesh;

[0073] Production process:

[0074] The pine board is immersed in 4 mol / L KOH aqueous solution under room temperature, continuously stirred for 24 h, taken out, washed with deionized water, and then immersed in 0.5 mol / L HCl aqueous solution, continuously stirred for 12 h to remove residual alkaline substances, and then taken out and stored in deionized water. The pretreated pine board and titanium metal mesh are arranged alternately, stacked layer by layer, and the outer two sides are the pretreated pine board, to construct a sandwich structure of 3 layers of pine board and 2 layers of titanium metal mesh, and the stacked material is compressed to a thickness of 20 mm by a tablet press. The compressed composite material is dried in an oven, and after complete drying, it is placed in a tube furnace, and the temperature of the tube furnace is raised at a rate of 5℃ / min under N2 protection, and the temperature is raised in stages, wherein the reaction is maintained at 350℃ for 1 h, and then the temperature is continuously raised to 800℃ for 30 min. After the reaction is stopped, the natural cooling to room temperature is performed, the biomass charcoal material is washed with deionized water until the effluent pH is 7, and then dried at 60℃ to obtain a biomass charcoal electrode material.

[0075] In the electrocatalytic oxidation device, the biomass charcoal material is used as the cathode, a Ru-In flat plate electrode with a length of 100 mm and a width of 80 mm is used as the anode, an electrocatalytic degradation system is constructed, and high-salt industrial wastewater is selected as the target pollutant for electrocatalytic degradation. The reaction conditions are as follows: constant current 10 mA / cm 2 , electrode spacing 1 cm, and reaction time 30 min. The TOC removal rate of the effluent is 99%, the mineralization rate reaches 70%, and after the reaction, the cathode has no structural phenomenon. Compared with the control electrocatalytic system using pure titanium plate or stainless steel plate as the cathode, the degradation performance of the system does not decrease significantly.

[0076] The preferred embodiments of the application are described in detail above with reference to the drawings, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, various possible combination manners are not described again in the application. However, these simple modifications and combinations should also be regarded as disclosed in the application and belong to the protection scope of the application.

Claims

1. A cathode plate for generating hydrogen peroxide, characterized by, The metal mesh (5) and the biomass charcoal layer (4) are alternately stacked, and the biomass charcoal layer (4) is distributed at least in the outer layer of the stack to coat the stacked surface of the metal mesh (5); The manufacturing method of the cathode plate comprises: S1: soaking the wooden material in an alkaline solution; S2: rinsing the wooden material soaked in the alkaline solution with deionized water, and then soaking it in an acidic solution to make the PH value of the wooden material 7, and finally storing it in deionized water; S3: stacking the wooden material stored in the deionized water and the metal mesh (5) at a distance from each other to form a composite material, and compressing the composite material; S4: high-temperature reaction of the compressed composite material, natural cooling, rinsing with deionized water until the water pH=7, and then drying at 60°C; N2 is continuously filled during the high-temperature reaction.

2. The cathode plate of claim 1, wherein The cathode plate comprises three biomass charcoal layers (4) and two metal meshes (5) arranged between the three biomass charcoal layers (4).

3. The cathode plate of claim 1, wherein The number of holes of the metal mesh (5) is 10-100 mesh, and the thickness is 1-3 mm.

4. The cathode plate of claim 1, wherein The metal mesh (5) is a titanium metal mesh.

5. The cathode plate of claim 1, wherein The biomass charcoal layer (4) is a wooden charcoal layer, and the thickness is 10-30 mm.

6. An electro-catalytic oxidation device, characterized by, It comprises a power supply (6), an anode plate (2) connected to the power supply (6), and a cathode plate (3) according to any one of claims 1-5 connected to the power supply (6).

7. The electro-catalytic oxidation device of claim 6, wherein, The material of the anode plate (2) is ruthenium-iridium alloy, the length is 90-110 mm, the width is 70-90 mm, and the thickness is 8-12 mm.

8. The electro-catalytic oxidation device of claim 6, wherein, The length of the cathode plate (3) is 90-110 mm, and the width is 70-90 mm; The thickness of the compressed cathode plate (3) is 10-30 mm.

9. The electro-catalytic oxidation device of claim 6, wherein, The length of the metal mesh (5) in the cathode plate (3) is 90-100 mm, the width is 70-80 mm, the thickness is 1-3 mm, and the number of holes is 10-100 mesh.

10. The electro-catalytic oxidation device of claim 6, wherein, The length of the biomass charcoal layer in the cathode plate (3) is 90-110 mm, the width is 70-90 mm, and the thickness is 10-30 mm.

11. A method for manufacturing a cathode plate for manufacturing the cathode plate according to any one of claims 1 to 5, characterized by, The manufacturing method comprises: S1: soaking the wooden material in an alkaline solution; S2: rinsing the wooden material soaked in the alkaline solution with deionized water, and then soaking it in an acidic solution to make the PH value of the wooden material 7, and finally storing it in deionized water; S3: stacking the wooden material stored in the deionized water and the metal mesh (5) at a distance from each other to form a composite material, and compressing the composite material; S4: high-temperature reaction of the compressed composite material, natural cooling, rinsing with deionized water until the water pH=7, and then drying at 60°C; The composite material is placed in a tube furnace for high-temperature reaction, which comprises: First process: the tube furnace is heated to 350°C at a rate of 5°C / min, and the reaction is maintained for 1h; Second process: the tube furnace is heated to 700-800°C at a rate of 5°C / min, and the reaction is maintained for 20-30 min; N2 is continuously filled during the high-temperature reaction.

12. The method of manufacturing a cathode plate according to claim 11, wherein In step S1, the wood material is oak, fir, elm, birch and nanmu.

13. The method of manufacturing a cathode plate according to claim 11, wherein In step S1, the temperature is room temperature, the alkaline solution is 2-4 mol / L NaOH or KOH, the soaking time is 24-48 h and the soaking process is continuously stirred.

14. The method of manufacturing a cathode plate according to claim 11, wherein In step S2, the temperature is room temperature, the acid solution is 0.5 mol / L HCl, the soaking time is 12 h and the soaking process is continuously stirred.

15. The method of manufacturing a cathode plate according to claim 11, wherein In step S3, a tablet press is used to compress the composite material which is stacked with mutual spacing.

16. The method of manufacturing a cathode plate according to claim 11, wherein Before the high-temperature reaction, the following steps are included: the compressed composite material is placed into an oven until completely dried.

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