Preparation process of open-cell structure nickel-aluminum foam electrode

Abstract

The application relates to a novel open-cell structure foamed nickel-aluminum electrode preparation process and relates to the technical field of sewage treatment. The process comprises the following steps: filling refractory material on a sponge prefabricated template; compacting the refractory material particles and the sponge, putting the compacted refractory material and sponge into a heating furnace for sintering, removing the sponge prefabricated template, leaving the sintered refractory material mold, and annealing and cooling; electrolyzing an aluminum oxide solution; pouring the electrolyzed aluminum oxide solution into the refractory material mold, applying pressure to the liquid metal through a solid pressure head above the refractory material mold after pouring is completed, so that the liquid metal penetrates into the refractory material mold, and performing cooling after sealing; after cooling, placing the refractory material mold in water, stripping and cleaning the refractory material, and obtaining foamed aluminum material; and performing electrodeposition on the foamed aluminum material in an acidic solution to prepare an electrode plate. The application has the advantages of increasing the specific surface area of the electrode plate and enhancing the effects of oxygen evolution and hydrogen evolution reactions in the electrochemical reaction process.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of sewage treatment, in particular to a preparation process of a novel open-pore structure foamed nickel-aluminum electrode. BACKGROUND

[0002] In an electrochemical reaction, water molecules are oxidized to produce oxygen at an anode, and hydrogen is reduced to produce hydrogen gas at a cathode. The average diameter of the generated oxygen and hydrogen bubbles is between 17 mu m and 50 mu m. Compared with a conventional dissolved air flotation technology, electrolytic water can generate smaller bubbles, which can effectively separate pollutant particles from a solution, and has been considered to be effective in treating aquaculture wastewater, printing and dyeing wastewater, oil-containing wastewater and the like.

[0003] In order to enhance the effect of electroflotation, there are two methods of increasing current density and increasing the area of the electrode plate. Increasing the current density will increase the energy consumption and the electrode plate will be quickly consumed. Increasing the area of the electrode plate by increasing the electrode plate will increase the cost and the area of the electrochemical reactor, and the economic benefit is low. Therefore, increasing the specific surface area of the electrode plate to enhance the effect of electroflotation becomes a more efficient choice.

[0004] In order to achieve the above-mentioned purpose of increasing the specific surface area of the electrode plate, a porous metal is generally used to achieve the purpose. The porous metal is also called foamed metal, which has a porous low-density structure. However, the foamed aluminum on the market is mostly made of a method of adding a foaming agent to form a porous structure, which generates bubbles in the molten metal, and the obtained structure is mostly closed, which is not conducive to the generation of electroflotation bubbles, resulting in low oxygen evolution and hydrogen evolution reaction intensity in the electrochemical reaction process, and thus needs to be improved. SUMMARY

[0005] In order to increase the specific surface area of the electrode plate and enhance the oxygen evolution and hydrogen evolution reaction in the electrochemical reaction process, the application provides a preparation process of a novel open-pore structure foamed nickel-aluminum electrode.

[0006] The preparation process of the novel open-pore structure foamed nickel-aluminum electrode provided by the application adopts the following technical scheme:

[0007] The preparation process of the novel open-pore structure foamed nickel-aluminum electrode comprises the following steps:

[0008] A sponge prefabricated template is prepared, and the prepared sponge prefabricated template is uniformly filled with refractory material;

[0009] The refractory material particles and the sponge are compacted above the sponge prefabricated template by a solid pressure head, and after compaction, the sponge prefabricated template is placed in a heating furnace for sintering. The sponge prefabricated template is removed by high temperature, and the sintered refractory material mold is left. The refractory material mold is annealed and cooled;

[0010] Electrolysis of the alumina solution by passing direct current with alumina as solute, carbon as anode and aluminum plate as cathode;

[0011] Casting the electrolyzed alumina solution into the refractory mold, and after the casting is completed, applying pressure to the liquid metal by a solid pressure head above the refractory mold to make the liquid metal infiltrate into the refractory mold, and after sealing, cooling;

[0012] After cooling, placing the refractory mold in water for 24 h, stripping and cleaning the refractory material embedded in the metal to obtain a foamed aluminum material;

[0013] Placing the foamed aluminum material with uniform openings into an acidic solution for electrodeposition to make an electrode plate.

[0014] Preferably, the refractory material comprises calcium chloride and magnesium sulfate, and the particles of the refractory material need to be ball milled, and the particle size of the refractory material is 50-100 μm.

[0015] Preferably, the temperature in the heating furnace is 580-650 ℃, the sintering time is 12 h, and the annealing cooling time is 24 h.

[0016] Preferably, the electrolysis of the alumina solution by passing direct current with alumina as solute, carbon as anode and aluminum plate as cathode further comprises adding fused cryolite as a cosolvent of the alumina solution.

[0017] Preferably, the casting temperature of the electrolyzed alumina solution is 950-980 ℃.

[0018] Preferably, the casting thickness of the electrolyzed alumina solution is 2 cm.

[0019] Preferably, the average pore size of the foamed aluminum material needs to be controlled to be 300-500 μm.

[0020] Preferably, the acidic solution is a nickel sulfate solution, and the deposition thickness of the nickel sulfate is 5-10 μm.

[0021] Preferably, the concentration of the acidic solution is 150-300 g / L.

[0022] Preferably, the electrodeposition voltage of the foamed aluminum material is 10 V, and the current density is 5 mA / cm 2 .

[0023] In summary, the present application has at least one of the following beneficial technical effects:

[0024] 1. The application uses porous metal materials with open hole structure as electrode materials for electrochemistry, greatly increasing the specific surface area of oxygen evolution and hydrogen evolution reactions;

[0025] 2. During the reaction process, the porous aluminum foam electrode can form a dense Al2O 3 thin film, preventing the electrode from being corroded and improving the safety during the reaction process;

[0026] 3. The doping of a nickel metal film on the surface of the porous aluminum foam material can effectively improve the electrode conductivity and the electrocatalytic activity of the foam electrode;

[0027] 4. During the electrochemical reaction process of the foam nickel aluminum electrode, the dissolved divalent nickel will be converted to high valence nickel ions, reducing the overpotential of the hydrogen evolution reaction, thereby triggering the electro-floating reaction at a lower voltage and achieving the purpose of reducing energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a preparation process flowchart of the embodiment of the application. EMBODIMENT

[0029] The following will be described in detail with reference to the accompanying Figure 1 The application will be further described in detail.

[0030] The embodiment of the application discloses a preparation process of a novel open hole structure foam nickel aluminum electrode.

[0031] Reference Figure 1 , comprising the following steps:

[0032] S1: preparing a sponge preform template, and uniformly filling refractory material on the prepared sponge preform template with an open hole structure; the refractory material can be granular calcium chloride and magnesium sulfate, and before the refractory material is filled, the refractory material particles need to be ball milled, and particles with a particle size in the range of 50 μm to 100 μm are screened out. In addition, the refractory material needs to meet the following conditions: (1) the melting point of the refractory material needs to be higher than that of electrolytic aluminum; (2) the refractory material needs to have sufficient strength and not be easily crushed under pressure; (3) the refractory material is easily dissolved in water, which is convenient for stripping and cleaning; in view of the above three conditions, the refractory material can be selected from other compounds meeting the conditions in addition to calcium chloride and magnesium sulfate.

[0033] S2: compacting the refractory material particles and the sponge above the sponge preform template by a solid pressure head, and after compaction, putting it into a heating furnace for sintering; the sintering temperature in the heating furnace is 580°C to 650°C, and the sintering duration is 12 hours; the sponge preform template is removed by high temperature, and the sintered refractory material mold is left; the refractory material mold is annealed and cooled, and the annealing and cooling duration is 24 hours.

[0034] S3: The alumina is taken as a solute, the carbon body is taken as an anode, the aluminum plate is taken as a cathode, the direct current is introduced, the electrolysis is carried out on the alumina solution, in the electrolysis process, the fused cryolite is added as a dissolving agent, so as to reduce the working temperature of the electrolyte, improve the fluidity of the solute, and generate the pure aluminum solution after the electrolysis of the alumina solution; the electrolyzed alumina solution is cast into the refractory material mold, the casting temperature of the electrolyzed alumina solution is 950-980 DEG C, if the temperature is too low, the metal viscosity is hit, the flow is uneven, and if the temperature is too high, the particles of the mold are melted, therefore, 950-980 DEG C can ensure the efficient process; the casting thickness of the pure aluminum solution is 2 cm; after the casting is completed, the solid pressure head is arranged above the refractory material mold to apply pressure on the liquid metal, so that the liquid metal penetrates into the refractory material mold, and the cooling is carried out after sealing.

[0035] S4: After cooling, the refractory material mold is placed in water for 24 h, the refractory organic compound embedded in the metal is stripped and cleaned, the foamed aluminum material is obtained, and the foamed aluminum material is measured to ensure that the average pore diameter of the generated foamed aluminum is between 300-500 mu m, and the minimum pore diameter is 200 mu m.

[0036] S5: The foamed aluminum material with uniform openings is placed in an acidic solution for electrodeposition, the acidic solution is a nickel sulfate solution, the voltage applied on the working electrode in the conventional electrolytic water reaction is usually 1.23 V, but there is a reaction energy barrier in the reaction, which leads to low hydrogen evolution reaction efficiency, and research shows that nickel-based metal is a good electrocatalytic material, and therefore is applied to the outside of the foamed electrode to enhance the hydrogen evolution reaction; wherein the deposition thickness of the nickel sulfate is 5-10 mu m, the concentration is 150-300 g / L, the electrodeposition voltage is 10 V, and the current density is 5 mA / cm 2 , and finally a nickel-aluminum electrode is prepared. Since the nickel plating layer is thin and has high porosity, it does not affect the hydrogen evolution and oxygen evolution reaction of the foamed aluminum.

[0037] The implementation principle of the novel foamed nickel-aluminum electrode preparation process of the application is as follows: a foamed aluminum electrode with uniform opening structure is prepared by using a prefabricated template method, and then the foamed aluminum electrode is placed in a nickel sulfate solution for electrodeposition to form a foamed nickel-aluminum electrode. Tests show that the foamed nickel-aluminum electrode can increase the specific surface area of the electrode plate, enhance the hydrogen evolution and oxygen evolution reactions in the electrochemical reaction process, and reduce the overvoltage of triggering the hydrogen evolution and oxygen evolution reactions, thereby achieving the purpose of energy saving. Thus, a foamed nickel-aluminum electrode with high efficiency, energy saving and enhanced electric flotation capacity is prepared and produced.

[0038] The above are preferred embodiments of the application, and do not limit the protection scope of the application, therefore: any equivalent changes made on the structure, shape and principle of the application should be covered within the protection scope of the application.

Claims

1. A process for preparing an open-cell structured nickel-aluminum electrode, characterized in that, It comprises the following steps: Preparation of a sponge preform and uniform filling of refractory material on the prepared sponge preform; Compaction of the refractory material particles and sponge by solid ram above the sponge preform, and sintering in a heating furnace after compaction, removal of the sponge preform by high temperature, and left the sintered refractory material mold, annealing and cooling of the refractory material mold; Electrolysis of the alumina solution by passing direct current with alumina as solute, carbon body as anode and aluminum plate as cathode, and adding molten cryolite as cosolvent of the alumina solution; Casting of the electrolyzed alumina solution into the refractory material mold, and after casting, applying pressure to the liquid metal by solid ram above the refractory material mold to make the liquid metal penetrate into the refractory material mold, and cooling after sealing; After cooling, the refractory material mold is placed in water for 24h, and the refractory material embedded in the metal is stripped and cleaned to obtain a foamed aluminum material; The uniformly porous foamed aluminum material is placed in an acidic solution for electrodeposition to make an electrode plate.

2. The process for preparing an open-cell structured nickel-aluminum foam electrode according to claim 1, characterized in that: The refractory material comprises calcium chloride and magnesium sulfate, and the particles of the refractory material need to be ball milled, and the particle size of the refractory material is 50-100μm.

3. The process for preparing an open-cell structured nickel-aluminum foam electrode according to claim 1, characterized in that: The temperature in the heating furnace is 580-650℃, the sintering time is 12h, and the annealing and cooling time is 24h.

4. The process for preparing an open-cell structured nickel-aluminum foam electrode according to claim 1, characterized in that: The casting temperature of the electrolyzed alumina solution is 950-980℃.

5. The process for preparing an open-cell structured nickel-aluminum foam electrode according to claim 1, characterized in that: The casting thickness of the electrolyzed alumina solution is 2cm.

6. The process for preparing an open-cell structured nickel-aluminum foam electrode according to claim 1, characterized in that: The average pore size of the foamed aluminum material needs to be controlled in the range of 300-500μm.

7. The process for preparing an open-cell structured nickel-aluminum foam electrode according to claim 1, characterized in that: The acidic solution is a nickel sulfate solution, and the deposition thickness of the nickel sulfate is 5-10μm.

8. The process for preparing an open-cell structured nickel-aluminum foam electrode according to claim 7, characterized in that: The concentration of the acidic solution is 150-300g / L.

9. The process for preparing an open-cell structured nickel-aluminum foam electrode according to claim 1, characterized in that: The electrodeposition voltage of the foam aluminum material is 10 V, and the current density is 5 mA / cm 2 .

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