Preparation method and device of an electrocatalytic dual-cathode reaction membrane and water treatment method

Abstract

The present invention discloses a preparation method and device of an electrocatalytic double cathode reaction membrane and a water treatment method, including a reaction cavity and a double cathode reaction membrane arranged in the reaction cavity. The double cathode reaction membrane includes a first cathode plate, an anode plate and a second cathode plate which are sequentially arranged from top to bottom in the reaction cavity. The reaction cavity has a first cathode chamber, an anode chamber and a second cathode chamber which are sequentially arranged from top to bottom and separate the first cathode plate, the anode plate and the second cathode plate. An inlet communicating with the first cathode chamber and an outlet communicating with the second cathode chamber are formed on the reaction cavity. Compared with the prior art, the present invention can generate two reactants required for the electro-Fenton reaction inside, without the need for additional addition of oxidants, and can be used in a closed environment terminal. It is not only applicable to large sewage treatment plants, but also can be directly installed at the user end as a miniaturized terminal product to be used as a water purification device.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical water treatment, and particularly to a preparation method and device of an electrocatalytic double cathode reaction membrane and a water treatment method. Background Art

[0002] While the construction of water treatment facilities in China is continuously advancing, high-concentration organic wastewater with complex components often receives attention. However, low-concentration organic wastewater is rarely treated and concerned due to high treatment costs, great technical difficulties, and less harmfulness compared to high-concentration wastewater. Currently, in the treatment of refractory organic matter in water treatment, advanced oxidation technology is very promising, and among them, the use of electro-Fenton technology is a newly developed technology. Compared with the traditional Fenton reaction, it uses Fe 2+ to react with H2O2 immediately after being generated in the system to produce •OH. Due to the high oxidation potential of •OH, it can oxidize and decompose almost all organic molecules with different intensities.

[0003] Currently, in the device for water treatment using electro-Fenton technology, usually only one of the reactants (Fe 2+ or H2O2) can be synthesized inside the device, and the other needs to be added externally. For the device that uses oxygen to generate H2O2 through a two-electron reduction reaction at the cathode, although it does not require additional addition of H2O2 and is not likely to produce toxic intermediate products, due to the need to use oxygen additionally, the reaction device needs to have a reaction aeration structure or an oxygen addition structure, and there is a process of reaction aeration or oxygen addition during the reaction process, which not only increases the structural complexity of the device but also increases the reaction time, resulting in low water treatment efficiency. However, if the method of directly adding an oxidant externally to the reaction device is used to generate H2O2, there are not only problems of oxidant residue but also limitations in the large-scale and multi-scenario applications of such water treatment devices. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a preparation method and device of an electrocatalytic double cathode reaction membrane and a water treatment method to solve the problems of complex device structure, low water treatment efficiency, oxidant residue, and limited application caused by the inability to synthesize all reactants internally in the prior art.

[0005] To solve the above technical problems, a technical solution provided by the present invention provides an electrocatalytic dual-cathode reaction membrane device, which includes a reaction cavity and a dual-cathode reaction membrane disposed in the reaction cavity. The dual-cathode reaction membrane includes a first cathode plate, an anode plate, and a second cathode plate sequentially arranged from top to bottom in the reaction cavity. A first cathode chamber, an anode chamber, and a second cathode chamber are sequentially arranged from top to bottom in the reaction cavity and are separated by the first cathode plate, the anode plate, and the second cathode plate. An inlet communicating with the first cathode chamber and an outlet communicating with the second cathode chamber are formed on the reaction cavity.

[0006] Further, the first cathode plate includes a first cathode substrate and a first cathode graphene layer deposited on the surface of the first cathode substrate; the thickness of the first cathode plate is 5-30 mm, the height of the first cathode graphene layer is 5-15 μm, and the size of the first cathode graphene layer is 1-10 μm.

[0007] Further, the second cathode plate includes a second cathode substrate, a second cathode graphene layer, and a ferrocene particle layer sequentially laminated and deposited on the surface of the second cathode substrate from the inside out; the thickness of the second cathode plate is 5-30 mm, the height of the second cathode graphene layer is 5-15 μm, and the size of the second cathode graphene layer is 1-10 μm.

[0008] Further, the anode plate includes an anode substrate and an anode graphene layer deposited on the surface of the anode substrate. A plurality of micropores are formed on the anode substrate; the thickness of the anode substrate is 5-30 mm, the pore diameter of the micropores is 10-30 μm, the height of the anode graphene layer is 5-15 μm, and the size of the anode graphene layer is 1-10 μm.

[0009] Further, a first insulating diaphragm is disposed between the first cathode plate and the anode plate in the reaction cavity, and a second insulating diaphragm is disposed between the anode plate and the second cathode plate. The first insulating diaphragm and the second insulating diaphragm divide the reaction cavity into the first cathode chamber, the anode chamber, and the second cathode chamber; a plurality of pores are formed on both the first insulating diaphragm and the second insulating diaphragm, and the size of the pores is 10-100 μm.

[0010] To solve the above technical problems, another technical solution of the present invention provides a preparation method of an electrocatalytic dual-cathode reaction membrane for preparing the dual-cathode reaction membrane as described above, including the following steps:

[0011] Prepare the raw materials into a first cathode substrate, a second cathode substrate, and an anode substrate respectively that are adapted to the inner cavity shape of the reaction cavity;

[0012] Pre-treat the first cathode substrate, the second cathode substrate and the anode substrate;

[0013] Deposit a first cathode graphene sheet, a second cathode graphene sheet and an anode graphene sheet on the pre-treated first cathode substrate, second cathode substrate and anode substrate respectively.

[0014] Furthermore, in the step of depositing the first cathode graphene sheet, the second cathode graphene sheet and the anode graphene sheet on the pre-treated first cathode substrate, second cathode substrate and anode substrate respectively, the specific methods for depositing the first cathode graphene sheet, the second cathode graphene sheet and the anode graphene sheet are as follows:

[0015] Adopt the PECVD process respectively, introduce a carbon source gas and a protective gas into the vacuum furnace simultaneously, turn on the DC power supply to dissociate the carbon source gas, and deposit carbon elements on the surface of the first cathode substrate to form a first cathode graphene sheet, deposit on the surface of the second cathode substrate to form a second cathode graphene sheet, and deposit on the surface of the anode substrate to form an anode graphene sheet.

[0016] Furthermore, during deposition, the pressure of the vacuum furnace is 2 - 5 Torr, the flow rate of the carbon source gas is 10 - 50 sccm, the flow rate of the protective gas is 500 - 2000 sccm, the deposition power is 300 - 800 W, and the deposition time is 10 - 30 min.

[0017] Furthermore, after the step of depositing the first cathode graphene sheet, the second cathode graphene sheet and the anode graphene sheet on the pre-treated first cathode substrate, second cathode substrate and anode substrate respectively, the following steps are further included:

[0018] Deposit a ferrocene particle layer on the second cathode graphene sheet; the specific method for depositing the ferrocene particle layer is as follows:

[0019] Place the second cathode substrate deposited with the second cathode graphene sheet at the position corresponding to the air extraction end in the vacuum furnace, and heat ferrocene in the heating area of the vacuum furnace; introduce a protective gas into the vacuum furnace, start air extraction, and make the ferrocene particles formed by heating adhere to the second cathode graphene sheet to form a ferrocene particle layer; the temperature of the heating area is 800 - 900 °C.

[0020] To solve the above technical problem, another technical solution of the present invention provides a water treatment method, which uses the dual cathode reaction membrane prepared by the electrocatalytic dual cathode reaction membrane device as described above or the preparation method of the electrocatalytic dual cathode reaction membrane as described above for water treatment.

[0021] The present invention is provided with a first cathode plate, an anode plate, and a second cathode plate arranged in sequence from top to bottom. H2O2 and Fe required for the electro-Fenton reaction 2+ can be generated on the first cathode plate and the second cathode plate respectively, without the need to additionally add Fe from the outside 2+ or H2O2, enabling the entire device to be used in a closed terminal without oxide residues, meeting the requirements of environmental protection, and eliminating the need to set up additional structures to add or generate H2O2 and Fe 2+ ; meanwhile, by setting the first cathode plate and the second cathode plate, different currents can be applied to the first cathode plate and the second cathode plate respectively, enabling the generation of H2O2 and the reduction of Fe 3+ simultaneously in the reaction cavity. The anode plate placed in the middle generates O2 by electrolyzing water. The O2 bubbles upward and contacts the first cathode plate, where it is converted into H2O2. The O2 generated by electrolyzing water is fully utilized to generate H2O2. At the same time, since the entire device is arranged vertically, the water flows downward under the action of water pressure and gravity. The generated H2O2 is carried by the water flow to the second cathode plate, where it is catalytically converted into •OH by ferrocene to remove small-molecule organic substances. Through such a cycle, the reaction can continue effectively to degrade low-concentration organic substances and can efficiently sterilize without residual oxidants in the water. It is not only applicable to large sewage treatment plants but also can be directly installed at the user end as a water purification device as a terminal product, without being restricted by the usage environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of the electrocatalytic double-cathode reaction membrane device of Embodiment 1 of the present invention.

[0023] Figure 2 is a flowchart of the preparation method of the electrocatalytic double-cathode reaction membrane of Embodiment 2 of the present invention.

[0024] Figure 3 is Figure 2 a flowchart of step S1 in

[0025] Figure 4 is a partial enlarged view of the first cathode graphene layer on the first cathode plate prepared in step S1.

[0026] Figure 5 is Figure 2 a flowchart of step S2 in

[0027] Figure 6 is a partial enlarged view of the second cathode graphene layer on the second cathode plate prepared in step S2.

[0028] Figure 7 is Figure 2 a flowchart of step S3 in

[0029] Figure 8 TOC test comparison chart of carbamazepine degradation by using the water treatment method of the present invention and the traditional water treatment method. Detailed implementation manners

[0030] The following is a further detailed description through specific implementation manners:

[0031] Example 1

[0032] As Figure 1 shown, it is a schematic structural diagram of an electrocatalytic dual-cathode reaction membrane device provided by an embodiment of the present invention. The electrocatalytic dual-cathode reaction membrane device of this embodiment includes a reaction cavity 1 and a dual-cathode reaction membrane arranged in the reaction cavity 1. An inlet 11 and an outlet 12 are arranged on the reaction cavity 1. After the dual-cathode reaction membrane is connected to direct current, it can react to generate H2O2 and Fe 2+ required for the electro-Fenton reaction, so as to treat the wastewater to be treated entering through the inlet 11 and flow out through the outlet 12 to the next treatment process. It can be understood that in this embodiment, the electrocatalytic dual-cathode reaction membrane device further includes other necessary components such as a DC power supply 5 in addition to the reaction cavity 1 and the dual-cathode reaction membrane. The positive and negative poles of the DC power supply 5 are respectively electrically connected to the corresponding positions of the dual-cathode reaction membrane to provide direct current for the dual-cathode reaction membrane. The DC power supply 5 can be implemented by using an existing structure or device, which will not be elaborated here.

[0033] The dual-cathode reaction membrane includes a first cathode plate 2, an anode plate 3, and a second cathode plate 4 arranged in the reaction cavity 1 from top to bottom in sequence. The first cathode plate 2 and the second cathode plate 4 are both electrically connected to the negative pole of the DC power supply 5, and the anode plate 3 is electrically connected to the positive pole of the DC power supply 5. During the reaction, the electric power input between the first cathode plate 2 and the anode plate 3 and between the first cathode plate 2 and the anode plate 3 is both 0.1~0.4W / cm 2 . The anode plate 3 can electrolyze water to generate O2 after being energized. Since the density of O2 is less than that of water, O2 floats to the first cathode plate 2. The first cathode plate 2 can convert O2 into H2O2, thus obtaining one of the reactants required for the electro-Fenton reaction. Since the density of H2O2 is greater than that of water, H2O2 is brought to the second cathode plate 4 under the action of its own density and the driving of water flow, and reacts with Fe 2+ (the other reactant required for the electro-Fenton reaction) provided by ferrocene on the second cathode plate 4 to be catalytically converted into •OH, thereby oxidizing and decomposing organic substances to achieve the purpose of wastewater treatment.

[0034] In this embodiment, the first cathode plate 2 is disposed above the anode plate 3, such that the O2 generated by the anode plate 3 can automatically float up and contact the first cathode plate 2, which can solve the problem that the O2 generated by electrolyzing water is not effectively utilized. At the same time, since O2 is generated by an internal reaction of the device, there is no need to additionally introduce oxygen or add an oxidant to generate H2O2, enabling the entire device to be used in a closed terminal without being restricted by the use environment. Meanwhile, the second cathode plate 4 is disposed below the anode plate 3. Under the action of its own density and water flow, H2O2 can quickly move to the second cathode plate 4 and be rapidly catalyzed to generate •OH, so as to increase the efficiency of water treatment. At the same time, the second cathode plate 4 is disposed on the movement path of H2O2, which can increase the utilization rate of H2O2 and further improve the efficiency of water treatment. In addition, the Fe 3+ generated by the electro-Fenton reaction can be regenerated into Fe 2+ through various reaction pathways (such as reduction reaction, etc.) and adhere to the second cathode plate 4, thereby avoiding the loss of Fe 2+ and enabling the reuse of Fe 2+ .

[0035] The first cathode plate 2 includes a first cathode substrate and a first cathode graphene layer deposited on the surface of the first cathode substrate. In this embodiment, the thickness of the first cathode plate 2 is 5 - 30 mm. Specifically, in implementation, the thickness of the first cathode plate 2 is comprehensively determined according to the thickness of the first cathode graphene layer and the filtration efficiency of liquids and gases. The first cathode substrate can be prepared from graphite, a gas diffusion electrode, or carbon fiber felt, and preferably a carbon fiber felt with a three-dimensional porous structure is used to increase the adhesion of the first cathode graphene layer, thereby improving the durability of the first cathode plate 2. The first cathode graphene layer is deposited by the PECVD process. The first cathode graphene layer is a vertical graphene layer, including a plurality of columnar graphene microstructures, to increase the specific surface area of the first cathode graphene layer, and further increase the reaction area on the surface of the first cathode plate 2, thereby improving the utilization rate of O2 and the generation rate of H2O2 and accelerating the process of water treatment. In this embodiment, the height of the graphene microstructures of the first cathode graphene layer is 5 - 15 μm, and preferably 10 μm. The size of the graphene microstructures of the first cathode graphene layer is 1 - 10 μm, and preferably 5 μm.

[0036] The second cathode plate 4 includes a second cathode substrate, and a second cathode graphene layer and a ferrocene particle layer that are sequentially laminated and deposited on the surface of the second cathode substrate from the inside outwards; in this embodiment, the thickness of the second cathode plate 4 is 5 to 30 mm. Specifically, when implemented, the thickness of the second cathode plate 4 is comprehensively determined according to the thickness of the second cathode graphene layer and the ferrocene particle layer and the filtration efficiency of liquids and gases. The second cathode substrate can be prepared from graphite, a gas diffusion electrode, or carbon fiber felt, and preferably a carbon fiber felt with a three-dimensional porous structure is used to increase the adhesion of the second cathode graphene sheets, thereby improving the durability of the second cathode plate 4. Similarly, the second cathode graphene layer is deposited by the PECVD process. The second cathode graphene layer is an upright graphene layer, including a number of columnar graphene microstructures to increase the specific surface area of the second cathode graphene layer, and further increase the adhesion area and adhesion strength of the ferrocene particle layer; in this embodiment, the height of the graphene microstructures of the second cathode graphene layer is 5 to 15 μm, and preferably 10 μm. The size of the graphene microstructures of the second cathode graphene layer is 1 to 10 μm, and preferably 5 μm. The ferrocene particle layer uses ferrocene as a target and is uniformly deposited on the second cathode graphene layer in the form of particles by the PECVD process. The Fe provided by ferrocene 2+ can undergo an electro-Fenton reaction with H2O2 generated on the first cathode plate 2 to generate •OH to oxidize and decompose organic substances in the wastewater; in this embodiment, when the ferrocene particle layer is deposited, the columnar graphene microstructures on the second cathode graphene layer can expand the reaction area between the ferrocene particle layer and the wastewater to be treated, thereby improving the conversion efficiency of Fe 2+ and the generation efficiency of •OH, and further accelerating the water treatment process.

[0037] The anode plate 3 includes an anode substrate and an anode graphene layer deposited on the surface of the anode substrate; in this embodiment, the thickness of the anode plate 3 is 5-30 mm. Specifically, when implemented, the thickness of the anode plate 3 is determined comprehensively according to the thickness of the subsequent film layer and the filtration efficiency of liquids and gases. A number of micropores are formed on the anode substrate, which can, on the one hand, ensure the transmittance of liquids and gases, and on the other hand, increase the adhesion of the anode graphene layer, thereby improving the durability of the first cathode plate 2; in this embodiment, the aperture of the micropores is 10-30 μm, and preferably 10 μm; the anode substrate can be prepared from a Ti metal plate, a carbon plate, reticulated vitreous carbon, polytetrafluoroethylene carbon or carbon fiber felt, and preferably carbon fiber felt is used. Similarly, the anode graphene layer is also deposited by the PECVD process. The anode graphene layer is a vertical graphene layer, including a number of columnar graphene microstructures, so as to increase the specific surface area of the anode graphene layer, and further improve the reaction area between the anode plate 3 and water, so that the anode graphene layer can improve the efficiency of electrolyzing water to produce O2 under good electrical conductivity; in addition, the anode graphene layer can also play a role in adsorbing and filtering bacteria; in this embodiment, the height of the graphene microstructures of the anode graphene layer is 5-15 μm, and preferably 10 μm, and the size of the graphene microstructures of the anode graphene layer is 1-10 μm, and preferably 5 μm.

[0038] A first insulating diaphragm 6 located between the first cathode plate 2 and the anode plate 3 and a second insulating diaphragm 7 located between the anode plate 3 and the second cathode plate 4 are further provided in the reaction chamber 1. The first insulating diaphragm 6 and the second insulating diaphragm 7 are used for insulation between the anode plate 3 and the first cathode plate 2 and the second cathode plate 4. In this embodiment, the first insulating diaphragm 6 and the second insulating diaphragm 7 are made of polytetrafluoroethylene films, on which a number of pores are formed for the passage of liquids and gases. The size of the pores is 10-100 μm, and preferably 50 μm.

[0039] The inner cavity of the reaction chamber 1 is divided by the first insulating diaphragm 6 and the second insulating diaphragm 7 into a first cathode chamber, an anode chamber and a second cathode chamber arranged in sequence from top to bottom. The first cathode plate 2, the anode plate 3 and the second cathode plate 4 are respectively placed in the first cathode chamber, the anode chamber and the second cathode chamber. The water inlet 11 is communicated with the first cathode chamber, and the water outlet 12 is communicated with the second cathode chamber.

[0040] When the electrocatalytic double-cathode reaction membrane device of this embodiment is in use, direct current is respectively passed between the first cathode plate 2 and the anode plate 3, and between the second cathode plate 4 and the anode plate 3. The wastewater to be treated enters from the water inlet 11 and flows downward through the first cathode chamber, the anode chamber, and the second cathode chamber in sequence. After being comprehensively treated by the first cathode plate 2, the anode plate 3, and the second cathode plate 4, it flows out from the water outlet 12. During the treatment, the anode plate 3 after being electrified electrolyzes water to generate O2. Under the action of its own density, O2 floats upward. When O2 contacts the first cathode plate 2, the first cathode plate 2 after being electrified converts O2 into H2O2. The generated H2O2 can quickly move to the second cathode plate 4 under the action of its own density and the drive of the water flow. Under the catalytic action of ferrocene on the second cathode plate 4, it is converted into •OH. •OH oxidizes and decomposes the organic matter in the wastewater to be treated, realizing the removal of small-molecule organic matter by the large-pore microfiltration membrane; the whole process can completely avoid adding oxidants from the outside, can be used in a closed environment terminal, effectively degrades low-concentration organic matter through continuous reaction and can sterilize efficiently, and will not leave oxidants in the water. It is not only applicable to large-scale sewage treatment plants, but also can be used as a miniaturized terminal product and directly installed at the user end as a water purification device. It has a simple structure and a large application range.

[0041] The electrocatalytic double-cathode reaction membrane device of this embodiment is described in terms of monomers (i.e., basic units). However, it can be understood that in actual use, the electrocatalytic double-cathode reaction membrane device monomers can be connected in series or in parallel according to the demand of the water treatment volume to form an array for use. When multiple devices are connected in series, the water outlet 12 of the previous device is connected to the water inlet 11 of the next device, and the wastewater passes through each device in sequence for treatment, which is suitable for water treatment sites with higher requirements for water treatment effects. When multiple devices are connected in parallel, the water inlets 11 of all devices are connected to each other and the water outlets 12 of all devices are connected to each other, and the wastewater is simultaneously treated by all devices, which is suitable for water treatment sites with higher requirements for water treatment efficiency, further expanding the application range of the present invention.

[0042] Example 2

[0043] Another embodiment of the present invention provides a preparation method of an electrocatalytic double-cathode reaction membrane for preparing the double-cathode reaction membrane in Example 1. The double-cathode reaction membrane of this embodiment includes the first cathode plate 2, the anode plate 3, and the second cathode plate 4 with the same or similar structures and functions as those in Example 1. The first cathode plate 2, the anode plate 3, and the second cathode plate 4 can be respectively prepared and then assembled into the reaction cavity 1. Therefore, for the convenience of describing this embodiment, the preparation of the first cathode plate 2, the anode plate 3, and the second cathode plate 4 will be described separately below.

[0044] Such as Figure 2As shown in the figure, it is a flowchart of the preparation method of the electrocatalytic double cathode reaction membrane of this embodiment. This embodiment specifically includes the following preparation steps:

[0045] S1: Prepare the first cathode plate 2.

[0046] Provide a first cathode substrate, and after pre-treating the first cathode substrate, deposit a layer of first cathode graphene flakes on the first cathode substrate to obtain the first cathode plate 2.

[0047] As Figure 3 shown, the step S1 includes the following steps:

[0048] S101: Prepare the first cathode substrate.

[0049] Specifically, select the raw material for preparing the first cathode substrate, and cut or stamp the raw material into a first cathode substrate adapted to the inner cavity shape of the reaction cavity 1. In this embodiment, the raw material for preparing the first cathode substrate is selected as a carbon fiber felt with a three-dimensional porous structure after carbonization of polyacrylonitrile; the carbonization temperature of the polyacrylonitrile is 1500 - 2000 °C, and preferably 1800 °C; the thickness of the first cathode substrate is 5 - 30 mm, and preferably 5 mm; the fiber diameter on the carbon fiber felt is 2 - 8 μm, and preferably 5 μm.

[0050] S102: Pre-treat the first cathode substrate.

[0051] First, immerse the first cathode substrate in a sulfuric acid solution to remove the rust generated on the surface of the first cathode substrate; in this embodiment, the concentration of the sulfuric acid solution is 2 - 5 mol / L, and preferably 2 mol / L, and the immersion time is 4 - 10 h, and preferably 6 h; it can be understood that in some other embodiments, other acidic solutions can also be used to immerse the first cathode substrate to achieve the purpose of removing rust. Then, repeatedly immerse and rinse the first cathode substrate treated by immersion in deionized water to remove the residual solution on the surface of the first cathode substrate; in this embodiment, the first cathode substrate can be repeatedly cleaned 20 - 50 times, preferably 30 times. Finally, place the first cathode substrate cleaned with deionized water in a drying oven for drying to remove the residual water stains on the surface of the first cathode substrate; in this embodiment, the temperature of the drying oven is preferably set at 100 °C, and the drying time is preferably 1 h, or as long as there is no residue on the surface of the first cathode substrate.

[0052] S103: Deposit the first cathode graphene flakes on the first cathode substrate.

[0053] Specifically, using the PECVD process, a carbon source gas is introduced into a vacuum furnace as a reaction gas, and a protective gas is simultaneously introduced into the vacuum furnace. The DC power supply is turned on to dissociate the carbon source gas, causing carbon elements to deposit on the surface of the first cathode substrate to form a first cathode graphene layer. After the deposition is completed, the first cathode substrate is taken out after cooling to room temperature to obtain the first cathode plate 2. In this embodiment, the carbon source gas is preferably CH4, the flow rate of the carbon source gas is 10 - 50 sccm, and preferably 20 sccm. The protective gas is preferably H2, the flow rate of the protective gas is 500 - 2000 sccm, and preferably 1000 sccm. The pressure in the vacuum furnace is 2 - 5 Torr, and preferably 3 Torr. The deposition power is 300 - 800 W, and preferably 500 W. The deposition time is 10 - 30 min, and preferably 15 min.

[0054] It can be understood that in some other embodiments, the carbon source gas can be replaced with a carbon target to prepare the first cathode graphene layer by sputtering deposition.

[0055] As Figure 4 shown, it is a partial enlarged view of the first cathode graphene layer on the first cathode plate 2 prepared by this embodiment. It can be clearly seen from the figure that the first cathode graphene layer with a thickness of about 5 - 100 nm and a length of about 1 μm is uniformly and firmly attached to the carbon fiber felt.

[0056] S2: Prepare the second cathode plate 4.

[0057] Provide a second cathode substrate, and after pre-treating the second cathode substrate, deposit a layer of second cathode graphene layer and a layer of ferrocene particle layer on the second cathode substrate in sequence to obtain the second cathode plate 4.

[0058] As Figure 5 shown, the step S2 includes the following steps:

[0059] S201: Prepare the second cathode substrate.

[0060] Specifically, select the raw material for preparing the second cathode substrate, and cut or stamp the raw material into a second cathode substrate adapted to the inner cavity shape of the reaction chamber 1. In this embodiment, the raw material for preparing the second cathode substrate is a carbon fiber felt with a three-dimensional porous structure obtained by carbonizing polyacrylonitrile. The carbonization temperature of the polyacrylonitrile is 1500 - 2000 °C, and preferably 1800 °C. The thickness of the second cathode substrate is 5 - 30 mm, and preferably 5 mm. The fiber diameter on the carbon fiber felt is 2 - 8 μm, and preferably 5 μm.

[0061] S202: Pre-treat the second cathode substrate.

[0062] First, immerse the second cathode substrate in a sulfuric acid solution to remove the rust generated on the surface of the second cathode substrate. In this embodiment, the concentration of the sulfuric acid solution is 2 - 5 mol / L, preferably 2 mol / L, and the immersion time is 4 - 10 h, preferably 6 h. It can be understood that in some other embodiments, other acidic solutions can also be used to immerse the second cathode substrate to achieve the purpose of removing rust. Then, repeatedly immerse and rinse the second cathode substrate treated by immersion in deionized water to remove the solution remaining on the surface of the second cathode substrate. In this embodiment, the second cathode substrate can be repeatedly cleaned 20 - 50 times, preferably 30 times. Finally, place the second cathode substrate cleaned with deionized water in a drying oven for drying to remove the water stains remaining on the surface of the second cathode substrate. In this embodiment, the temperature of the drying oven is preferably set at 100°C, and the drying time is preferably 1 h, or the surface of the second cathode substrate has no residue.

[0063] S203: Deposit a second cathode graphene flake layer on the second cathode substrate.

[0064] Specifically, adopt the PECVD process, introduce a carbon source gas as a reaction gas into a vacuum furnace, and at the same time introduce a protective gas into the vacuum furnace, and turn on the DC power supply to dissociate the carbon source gas so that carbon elements are deposited on the surface of the second cathode substrate by sputtering to form a second cathode graphene flake layer. In this embodiment, the carbon source gas preferably uses CH4, the flow rate of the carbon source gas is 10 - 50 sccm, preferably 20 sccm, the protective gas is preferably H2, the flow rate of the protective gas is 500 - 2000 sccm, preferably 1000 sccm, the pressure of the vacuum furnace is 2 - 5 Torr, preferably 3 Torr, the deposition power is 300 - 800 W, preferably 500 W, and the deposition time is 10 - 30 min, preferably 15 min.

[0065] It can be understood that in some other embodiments, the carbon source gas can be replaced with a carbon target to prepare the second cathode graphene flake layer by sputtering deposition.

[0066] S204: Deposit a ferrocene particle layer on the second cathode graphene flake layer.

[0067] Specifically, place the second cathode substrate deposited with the second cathode graphene flakes at the position corresponding to the air extraction end of the vacuum furnace. Use a corundum crucible to hold ferrocene, place the corundum crucible containing ferrocene in the heating zone of the vacuum furnace for heating, and introduce a protective gas into the vacuum furnace. Start air extraction. The heating zone heats ferrocene to generate ferrocene particles, and the ferrocene particles can be evenly attached to the second cathode graphene flakes with the gas flow to form a ferrocene particle layer. After the deposition is completed, take out the second cathode substrate after it cools to room temperature to obtain the second cathode plate 4. In this embodiment, the temperature of the heating zone is 800-900 °C, and preferably 900 °C, and the protective gas is preferably Ar.

[0068] As Figure 6 shown, it is a partial enlarged view of the second cathode graphene flakes on the second cathode plate 4 prepared by using this embodiment. It can be clearly seen from the figure that the second cathode graphene flakes with a thickness of about 5-100 nm and a length of about 1 μm are evenly and firmly attached to the carbon fiber felt, and evenly distributed ferrocene particles can be seen on the second cathode graphene flakes.

[0069] S3: Prepare the anode plate 3.

[0070] Provide an anode substrate, and after pre-treating the anode substrate, deposit a layer of anode graphene flakes on the anode substrate to obtain the anode plate 3.

[0071] As Figure 7 shown, the step S3 includes the following steps:

[0072] S301: Prepare the anode substrate.

[0073] Specifically, select the raw material for preparing the anode substrate, and cut or stamp the raw material into an anode substrate adapted to the inner cavity shape of the reaction chamber 1. In this embodiment, the raw material for preparing the anode substrate is selected as the carbon fiber felt after carbonizing polyacrylonitrile. There are several micropores on the carbon fiber felt; the carbonization temperature of the polyacrylonitrile is 1500-2000 °C, and preferably 1800 °C; the thickness of the anode substrate is 5-30 mm, and preferably 5 mm; the pore diameter of the micropores on the carbon fiber felt is 10-30 μm, and preferably 10 μm.

[0074] S302: Pre-treat the anode substrate.

[0075] First, immerse the anode substrate in a sulfuric acid solution to remove the rust generated on the surface of the anode substrate. In this embodiment, the concentration of the sulfuric acid solution is 2 - 5 mol / L, and preferably 2 mol / L, the immersion time is 4 - 10 h, and preferably 6 h. It can be understood that in some other embodiments, other acidic solutions can also be used to immerse the anode substrate to achieve the purpose of removing rust. Then, place the anode substrate after immersion treatment in an ultrasonic cleaning device for ultrasonic oscillation to remove impurities such as particles attached to the anode substrate. In this embodiment, the ultrasonic oscillation time is 20 - 30 min, and preferably 30 min. Next, repeatedly immerse and rinse the anode substrate after ultrasonic oscillation in deionized water to remove the residual solution on the surface of the anode substrate. In this embodiment, the anode substrate can be repeatedly cleaned 20 - 50 times, preferably 30 times. Finally, place the anode substrate after deionized water cleaning in a drying oven for drying to remove the residual water stains on the surface of the anode substrate. In this embodiment, the temperature of the drying oven is preferably set at 100 °C, the drying time is preferably 1 h, or it is okay as long as there is no residue on the surface of the anode substrate.

[0076] S303: Deposit an anodic graphene layer on the anode substrate.

[0077] Specifically, adopt the PECVD process, introduce a carbon source gas as a reaction gas into a vacuum furnace, and at the same time introduce a protective gas into the vacuum furnace. Connect a DC power supply to dissociate the carbon source gas so that carbon elements are deposited on the surface of the anode substrate by sputtering to form an anodic graphene layer. After the deposition is completed, take out the anode substrate after it cools to room temperature to prepare the anode plate 3. In this embodiment, the carbon source gas preferably uses CH4, the flow rate of the carbon source gas is 10 - 50 sccm, and preferably 20 sccm, the protective gas is preferably H2, the flow rate of the protective gas is 500 - 2000 sccm, and preferably 1000 sccm, the pressure of the vacuum furnace is 2 - 5 Torr, and preferably 3 Torr, the deposition power is 300 - 800 W, and preferably 500 W, the deposition time is 10 - 30 min, and preferably 15 min.

[0078] It can be understood that in some other embodiments, the carbon source gas can be replaced with a carbon target to prepare the anodic graphene layer by sputtering deposition.

[0079] S4: Assemble to obtain a dual-cathode reaction membrane.

[0080] Specifically, assemble the prepared first cathode plate 2, anode plate 3, and second cathode plate 4 in this order from top to bottom in the reaction cavity 1 to obtain a dual-cathode reaction membrane.

[0081] In this embodiment, since the first cathode plate 2, the anode plate 3, and the second cathode plate 4 can be separately fabricated and then assembled into the reaction chamber 1, the order of steps S1 to S3 is not limited to the above preparation order.

[0082] As a preferred embodiment of the present invention, a water treatment method is also provided, which uses the dual-cathode reaction membrane prepared by the electrocatalytic dual-cathode reaction membrane device described in Example 1 or the preparation method of the electrocatalytic dual-cathode reaction membrane described in Example 2 for water treatment.

[0083] Specifically, taking the degradation of carbamazepine as an example, the water treatment method of this embodiment specifically includes:

[0084] Assemble the reaction chamber 1 with an inlet 11 and an outlet 12, the first cathode plate 2, the anode plate 3, the second cathode plate 4, the DC power supply 5, the first insulating diaphragm 6, and the second insulating diaphragm 7 according to the structure of Example 1.

[0085] First, weigh 100 mg of carbamazepine, heat and dissolve it in an alkaline environment. After cooling to room temperature, make up the volume to 1000 mL in a volumetric flask and then refrigerate it in a 4°C refrigerator. Then, add anhydrous sodium sulfate. After the anhydrous sodium sulfate is completely dissolved, add sodium hydroxide and sulfuric acid to adjust the pH. Next, stir evenly and then pass a constant DC current for the reaction, and keep the influent flow rate constant until the reaction ends. Finally, maintain a constant temperature of 298 K at room temperature, and set the influent flow rate to 10 mL / min.

[0086] Sample at intervals within the set time. Add 0.8 mL of the sample to a 1.5 mL brown liquid-phase vial, shake well and place it in a freeze-drying box. When sampling, select time intervals of 0, 5, 10, 20, 25, and 30 min for sampling, and measure the TOC with a TOC analyzer.

[0087] As Figure 8 shown, it is a comparison chart of the degradation efficiency of carbamazepine by the water treatment method of this embodiment and the degradation efficiency of the traditional water treatment method. It can be seen that the water treatment method of this embodiment has significantly higher removal effect on organic matter than the traditional water treatment method.

Claims

1. An electrocatalytic dual-cathode reaction membrane device, comprising a reaction cavity and a dual-cathode reaction membrane disposed in the reaction cavity, characterized in that, The dual-cathode reaction membrane includes a first cathode plate, an anode plate, and a second cathode plate that are sequentially arranged from top to bottom in the reaction cavity. The first cathode plate includes a first cathode substrate and a first cathode graphene layer deposited on the surface of the first cathode substrate; the second cathode plate includes a second cathode substrate and a second cathode graphene layer and a ferrocene particle layer that are sequentially laminated and deposited on the surface of the second cathode substrate from inside to outside; the anode plate includes an anode substrate and an anode graphene layer deposited on the surface of the anode substrate; a first cathode chamber, an anode chamber, and a second cathode chamber are sequentially arranged from top to bottom in the reaction cavity and separate the first cathode plate, the anode plate, and the second cathode plate. An inlet communicating with the first cathode chamber and an outlet communicating with the second cathode chamber are formed on the reaction cavity; after the anode plate is powered on, water can be electrolyzed to generate O2. Since the density of O2 is less than that of water, O2 floats to the first cathode plate. The first cathode plate can convert O2 into H2O2. Since the density of H2O2 is greater than that of water, H2O2 is brought to the second cathode plate under the action of its own density and water flow, and reacts with Fe 2+ catalytically converted into •OH.

2. The electrocatalytic double cathode reaction membrane device according to claim 1, wherein The thickness of the first cathode plate is 5 - 30 mm, the height of the first cathode graphene lamella is 5 - 15 μm, and the size of the first cathode graphene lamella is 1 - 10 μm.

3. The electrocatalytic double cathode reaction membrane device according to claim 1, characterized in that The thickness of the second cathode plate is 5 - 30 mm, the height of the second cathode graphene layer is 5 - 15 μm, and the size of the second cathode graphene lamella is 1 - 10 μm.

4. The electrocatalytic double cathode reaction membrane device according to claim 1, characterized in that, A number of micropores are formed on the anode substrate; the thickness of the anode substrate is 5 - 30 mm, the pore diameter of the micropores is 10 - 30 μm, the height of the anode graphene layer is 5 - 15 μm, and the size of the anode graphene lamella is 1 - 10 μm.

5. The electrocatalytic double cathode reaction membrane device according to claim 1, wherein A first insulating diaphragm located between the first cathode plate and the anode plate and a second insulating diaphragm located between the anode plate and the second cathode plate are further provided in the reaction cavity. The first insulating diaphragm and the second insulating diaphragm divide the reaction cavity to form the first cathode chamber, the anode chamber and the second cathode chamber; a number of pores are formed on both the first insulating diaphragm and the second insulating diaphragm, and the size of the pores is 10 - 100 μm.

6. A method for preparing an electrocatalytic dual-cathode reaction membrane, which is used to prepare the dual-cathode reaction membrane as described in any one of claims 1 to 5, characterized in that, It includes the following steps: Prepare the raw materials into a first cathode substrate, a second cathode substrate and an anode substrate respectively that are adapted to the inner cavity shape of the reaction cavity. Perform pretreatment on the first cathode substrate, the second cathode substrate and the anode substrate. Deposit a first cathode graphene lamella, a second cathode graphene lamella and an anode graphene lamella on the pretreated first cathode substrate, second cathode substrate and anode substrate respectively.

7. The preparation method of the electrocatalytic dual-cathode reaction membrane according to claim 6, wherein: In the step of depositing the first cathode graphene lamella, the second cathode graphene lamella and the anode graphene lamella on the pretreated first cathode substrate, second cathode substrate and anode substrate respectively, the specific methods for depositing the first cathode graphene lamella, the second cathode graphene lamella and the anode graphene lamella are as follows: Adopt the PECVD process respectively, simultaneously introduce a carbon source gas and a protective gas into a vacuum furnace, and turn on a DC power supply to dissociate the carbon source gas so that carbon elements are deposited on the surface of the first cathode substrate to form the first cathode graphene lamella, deposited on the surface of the second cathode substrate to form the second cathode graphene lamella, and deposited on the surface of the anode substrate to form the anode graphene lamella.

8. The preparation method of the electrocatalytic double cathode reaction membrane according to claim 7, characterized in that During deposition, the pressure of the vacuum furnace is 2 - 5 Torr, the flow rate of the carbon source gas is 10 - 50 sccm, the flow rate of the protective gas is 500 - 2000 sccm, the deposition power is 300 - 800 W, and the deposition time is 10 - 30 min.

9. The preparation method of the electrocatalytic double cathode reaction membrane according to claim 6, wherein: After the step of depositing the first cathode graphene lamella, the second cathode graphene lamella and the anode graphene lamella on the pretreated first cathode substrate, second cathode substrate and anode substrate respectively, the following steps are further included: Deposit a ferrocene particle layer on the second cathode graphene lamella; the specific method for depositing the ferrocene particle layer is as follows: Place the second cathode substrate deposited with the second cathode graphene flakes at the position corresponding to the air extraction end in a vacuum furnace, and place ferrocene in the heating zone of the vacuum furnace for heating; introduce a protective gas into the vacuum furnace, start air extraction, so that the ferrocene particles formed by heating adhere to the second cathode graphene flakes to form a ferrocene particle layer; the temperature of the heating zone is 800-900 °C.

10. A water treatment method, characterized in that, Use the dual cathode reaction membrane prepared by the electrocatalytic dual cathode reaction membrane device according to any one of claims 1-5 or the preparation method of the electrocatalytic dual cathode reaction membrane according to any one of claims 6-9 for water treatment.

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