Novel gas diffusion electrode reactor with hollow chamber

Abstract

The utility model relates to a novel gas diffusion electrode reactor with a hollow chamber. The novel gas diffusion electrode reactor structurally comprises an anode tank, a cathode tank and an aeration stirring device, the anode tank is of a square box body structure with an opening in the upper part, and iron particle layers are respectively arranged on four inner surfaces of the anode tank; the cathode tank is located in an inner cavity of the anode tank, a gas diffusion electrode is arranged on the cathode tank, and the outer surface of the gas diffusion electrode is coated with a catalyst; the iron particle layer and the gas diffusion electrode are connected with positive and negative electrodes of a power supply through circuits; and the aeration stirring device is positioned below the cathode tank. The gas diffusion electrode of the reactor performs electro-Fenton reaction, pure oxygen exposure is not needed, and oxygen in air can be directly utilized to efficiently synthesize H2O2; the cathode and the anode are controlled by the cathode and anode conversion assembly to generate oxidation-reduction reaction, so that the problem of high sludge yield can be effectively solved; by arranging the scattered point type aeration device and utilizing the upward floating motion of bubbles, the energy consumption is reduced, the dissolved oxygen content is increased, and the reaction efficiency is improved.

Description

Technical Field

[0001] The utility model relates to a novel gas diffusion electrode reactor with a hollow chamber, belonging to the technical field of electrochemical devices. Background Art

[0002] At present, the treatment of refractory organic pollutants by advanced oxidation processes (AOPs) to avoid their potential environmental risks has received widespread attention. As an efficient and clean oxidant, hydrogen peroxide has been widely used in AOPs. In H2O2-based AOPs, the highly oxidizing hydroxyl radicals (·OH) produced by the medium play an important role in the treatment of organic pollutants. The in-situ electrochemical oxygen reduction reaction to synthesize ·OH is a green and convenient production method, and avoids the dangers of H2O2 storage and transportation, so it is very ideal. For electrochemical reactions involving gas, compared with traditional aeration methods, gas diffusion electrodes are currently more ideal electrode devices.

[0003] Gas diffusion electrode is a special porous membrane electrode. Since a large amount of gas can reach the inside of the electrode and is connected to the overall solution (electrolyte) outside the electrode, it can form a three-phase (solid, liquid, gas) membrane electrode. It is mainly composed of a substrate layer, a diffusion layer and a catalyst layer. The substrate layer mainly plays the role of conductivity and support; the diffusion layer mainly plays the role of gas transmission; the catalyst layer is the place where the gas reacts. The "gas-solid-liquid" three-phase reaction interface is constructed in the catalyst layer so that the gas can undergo an electrochemical reaction here.

[0004] Traditional Fenton reagents consume a lot of energy, have poor mass transfer effects, low reaction efficiency, and produce a lot of sludge. Moreover, for traditional electrodes, since the solubility of gas in the solution is very low, in order not to be affected by mass transfer, aeration is often used. Such measures waste a lot of gas and cause excessive waste of resources. For electrosynthesis of H2O2, gas diffusion electrodes allow oxygen to be directly supplied to the cathode surface from the outside through the back of the electrode without dissolving it in the electrolyte, thereby improving the efficiency of the electrochemical reaction. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a novel gas diffusion electrode reactor with a hollow chamber. The gas diffusion electrode of the reactor carries out an electro-Fenton reaction without exposure to pure oxygen, and can directly utilize oxygen in the air to efficiently synthesize H2O2; the cathode and anode are controlled to undergo redox reactions by anode-cathode conversion components, which can effectively solve the problem of large sludge production; a scattered aeration device is provided, and the upward movement of the bubbles themselves is utilized to achieve mass transfer and prevent concentration polarization, while reducing energy consumption, increasing the dissolved oxygen content, and improving reaction efficiency.

[0006] In order to solve the above problems, the specific technical scheme of the utility model is as follows: a novel gas diffusion electrode reactor with a hollow chamber, comprising an anode tank, a cathode tank and an aeration and stirring device; the anode tank is a square box structure with an upper opening, and iron particle layers are respectively arranged on the four inner surfaces of the anode tank; the cathode tank is located in the inner cavity of the anode tank, and a gas diffusion electrode is arranged on the cathode tank, and the outer surface of the gas diffusion electrode is coated with a catalyst; a hanging wall plate is arranged on the top of the cathode tank, and the hanging wall plate is horizontally supported on the upper end surface of the anode tank; the aeration and stirring device consists of a scattered gas chamber, an air pump and a gas pipeline, and a plurality of evenly distributed pores are arranged on the upper surface of the scattered gas chamber, the scattered gas chamber is located on the bottom surface of the inner cavity of the anode tank and corresponds to the position of the cathode tank, the lower part of the scattered gas chamber is connected to one end of the gas pipeline, and the other end of the gas pipeline extends from the anode tank and is connected to the air pump; wherein the iron particle layer and the gas diffusion electrode are connected to the positive and negative poles of the power supply through the circuit.

[0007] The cathode tank is a cylindrical structure with an opening at the top, and four square openings of equal size are provided on the circumferential surface of the cathode tank. The gas diffusion electrode with a catalyst coated on the outer surface is a cylindrical structure of equal diameter and is located in the cathode tank, and each square opening corresponds to the position of the iron particle layer of the anode tank.

[0008] The scattered point air chamber is in a flat rectangular parallelepiped structure, and the side with a larger area is located at the top.

[0009] The circuit includes a DC power supply and two bidirectional knife switches, the output end of the upper knife switch is connected to the iron particle layer, the output end of the lower knife switch is connected to the gas diffusion electrode, and four contacts are set on both sides of the bidirectional knife switch. When the upper and lower knife switches are connected to the contacts on the left side at the same time, the gas diffusion electrode is connected to the positive electrode of the DC power supply, and the iron particle layer is connected to the negative electrode of the DC power supply; when the upper and lower knife switches are connected to the contacts on the right side at the same time, the gas diffusion electrode is connected to the negative electrode of the DC power supply, and the iron particle layer is connected to the positive electrode of the DC power supply.

[0010] The upper surface of the anode tank is provided with four grooves; the two hanging wall plates on the upper part of the cathode tank are arranged in parallel and clamped in the corresponding grooves.

[0011] The novel hollow chamber gas diffusion electrode reactor of the present application adopts the above structure and has the following advantages:

[0012] The cylindrical cathode tank of the reactor is placed inside the anode tank, a gas diffusion electrode is placed on the inner wall of the cathode tank, four square open areas of equal size are set on the side wall of the cathode tank, and an iron particle layer is placed in the corresponding area of ​​the side wall of the anode tank. Compared with the traditional electro-Fenton reactor, the effective contact area of ​​the reaction is increased and the degradation efficiency is improved.

[0013] The electro-Fenton reaction is carried out through a gas diffusion electrode. A gas diffusion electrode is placed on the inner wall of the cathode cell, and a hollow gas chamber is formed inside the cathode cell. Air can be supplied from the chamber directly to the cathode surface through the back of the electrode, and a two-electron oxygen reduction reaction of oxygen occurs to generate H2O2 without the need for it to dissolve in the electrolyte, thereby improving the efficiency of the electrochemical reaction, effectively reducing energy consumption, and effectively avoiding the transportation and storage of H2O2.

[0014] The electrode group is composed of a gas diffusion electrode and an iron particle layer, which are electrically connected to the cathode and anode conversion components respectively. The cathode and anode conversion components are used to control the redox reaction of the cathode and anode to promote the Fe 2+ The recycling regeneration can effectively solve the problem of large sludge production.

[0015] By setting up a scattered aeration device, air bubbles are evenly introduced from the bottom of the anode tank, which not only plays a stirring role, but also uses the upward movement of the bubbles themselves to blow up the precipitated iron sludge. While achieving mass transfer and preventing concentration polarization, it reduces energy consumption, increases dissolved oxygen content, and improves reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the overall structure of the reactor of this application.

[0017] Figure 2 Schematic diagram of the structure of the anode tank.

[0018] Figure 3 Schematic diagram of the cathode cell structure.

[0019] Figure 4 This is a diagram of the gas diffusion electrode structure.

[0020] Figure 5 A schematic diagram of the aeration device.

[0021] Figure 6 This is a circuit connection diagram. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings.

[0023] The inventors analyzed the existing technologies and found that the traditional electro-Fenton technology has the characteristics of high requirements for cathode materials and low Fenton reagent output during actual operation. Therefore, the electro-Fenton technology needs to add H2O2 to improve the reaction efficiency in actual operation, and the transportation and storage costs of H2O2 are relatively high. In addition, the traditional electro-Fenton technology also has the problems of large amount of mud generated and large amount of iron loss during the reaction process.

[0024] like Figures 1 to 5As shown, a novel gas diffusion electrode reactor with a hollow chamber comprises an anode tank 1, a cathode tank 2 and an aeration stirring device 3, both of which are made of organic glass; the anode tank 1 is a square box structure with an upper opening, and iron particle layers 1-1 are respectively arranged on the four inner surfaces of the anode tank 1; the cathode tank 2 is located in the inner cavity of the anode tank 1, and a gas diffusion electrode 2-1 is arranged on the cathode tank 2, and a catalyst 2-2 is coated on the outer surface of the gas diffusion electrode 2-1; four grooves 1-2 are arranged on the upper surface of the anode tank 1, and two parallel hanging wall panels 2-4 are arranged on the top of the cathode tank 2, and the hanging wall panels 2-4 are clamped in the corresponding grooves 1-2 of the anode tank 1; the aeration stirring device 3 consists of a scattered gas chamber 3-1, an air chamber 3-2, and a gas diffusion electrode 2-1. The air pump 3-2 and the gas pipeline 3-3 are composed, and the upper surface of the scattered air chamber 3-1 is provided with a plurality of evenly distributed pores 3-4, and the scattered air chamber 3-1 is located at the bottom surface of the inner cavity of the anode tank 1 and corresponds to the position of the cathode tank 2, and the lower part of the scattered air chamber 3-1 is connected to one end of the gas pipeline 3-3, and the other end of the gas pipeline 3-3 extends from the anode tank 1 and is connected to the air pump 3-2. The scattered air chamber 3-1 is a flat rectangular structure, and the side with a large area is located at the top, so that the bubbles generated by the aeration device rise evenly, which plays a stirring role, and also increases the dissolved oxygen content in the electrolyte, thereby improving the reaction efficiency; wherein the iron particle layer 1-1 and the gas diffusion electrode 2-1 are connected to the positive and negative poles of the power supply through the circuit. The cathode slot 2 is a cylindrical structure with an opening at the top, and four square openings 2-3 of equal size are provided on the circumferential surface of the cathode slot 2. The gas diffusion electrode 2-1 with a catalyst 2-2 coated on the outer surface is a cylindrical structure of equal diameter and is located in the cathode slot 2. Each square opening 2-3 corresponds to the position of the iron particle layer 1-1 of the anode slot 1.

[0025] like Figure 6 As shown, the circuit includes a DC power supply 4-1 and two bidirectional knife switches 4-2, the output end of the upper knife switch is connected to the iron particle layer 1-1, and the output end of the lower knife switch is connected to the gas diffusion electrode 2-1, and four contacts are set on both sides of the bidirectional knife switch 4-2. When the upper and lower knife switches 4-2 are connected to the contacts on the left side at the same time, the gas diffusion electrode 2-1 is connected to the positive pole of the DC power supply 4-1, and the iron particle layer 1-1 is connected to the negative pole of the DC power supply 4-1; when the upper and lower knife switches 4-2 are connected to the contacts on the right side at the same time, the gas diffusion electrode 2-1 is connected to the negative pole of the DC power supply 4-1, and the iron particle layer 1-1 is connected to the positive pole of the DC power supply 4-1.

[0026] The working process of the novel hollow chamber gas diffusion electrode reactor of the present application is as follows: a gas diffusion electrode 2-1 loaded with a catalyst 2-2 is placed on the inner wall of the cathode tank 2, and is fixed to the inner wall of the cathode tank 2 by a number of iron sheet clips 18 of suitable length. The cathode tank 2 is then fixed to the groove 1-2 of the anode tank 1 by a suspension arm plate 2-4. An iron particle layer 1-1 is placed on the side wall corresponding to the gas diffusion electrode 2-1 inside the anode tank 1 and fixed by an iron sheet clip 18. First, open the aeration device 3, and then put the pretreated wastewater into the anode tank 1 to prevent the wastewater from entering the scattered aeration device from the air hole 9, causing damage to the device. The wastewater needs to cover the upper edge of the square opening 2-3 area of ​​the cathode tank 2. The gas diffusion electrode 2-1 and the iron particle layer 1-1 are respectively connected in series with the DC power supply 4-1, and the two-way knife switch 4-2 is respectively connected to the left and right contacts to control the direction of the current. The external DC power supply 4-1 provides a potential voltage. At the beginning of the reaction, the gas diffusion electrode 2-1 supplies oxygen from the outside directly to the cathode surface through the back of the electrode, and a two-electron reduction reaction of oxygen occurs: O2+2H + +2e - → H2O2 generates H2O2 without additional addition, which greatly saves transportation and storage costs. At this time, the two-way knife switch 4-2 is turned on, and the knife switch 4-2 is connected to the contact on the right. The DC power supply 4-1 applies voltage and current to the electrodes, where the iron particle layer 1-1 is the anode and the gas diffusion electrode is the cathode, realizing Fe 2+ Rapid precipitation of Fe 2+ Reacts with hydrogen peroxide in water to form Fe 3+ , part of Fe 3+ Hydrolysis reaction occurs to produce Fe(OH)3, which is deposited at the bottom of the electrolytic cell. 3+ As the bubbles float up, a reduction reaction occurs, achieving Fe 3+ To Fe 2+ The conversion of Fe 2+ It can react with residual hydrogen peroxide to produce Fenton reaction again, thus improving the reaction efficiency.

[0027] When there are more iron oxides deposited on the surface of the anode tank 1 and the scattered gas chamber 3-1, it is easy to block the scattered pores and reduce the mass transfer efficiency. At this time, the aeration volume of the scattered gas chamber is increased, and the two-way knife switch 12 is turned at the same time. The knife switch 12 is connected to the contact on the left. At this time, the voltage is applied in the reverse direction, in which the iron particle layer 17 is the cathode and the gas diffusion electrode is the anode. The deposited iron oxide undergoes a reduction reaction: Fe2O3 +6H + +2e - →2Fe 2+ +3H2O, which not only removes the iron oxide deposits and reduction products at the bottom of the electrolytic cell, but also replenishes the amount of Fenton reagent in the bed, realizes the in-situ regeneration of iron, improves the utilization rate of iron, and purifies the wastewater.

Claims

1. A novel hollow chamber gas diffusion electrode reactor, characterized in that: The invention comprises an anode tank (1), a cathode tank (2) and an aeration and stirring device (3); the anode tank (1) is a square box structure with an upper opening, and iron particle layers (1-1) are respectively provided on four inner surfaces of the anode tank (1); the cathode tank (2) is located in the inner cavity of the anode tank (1), and a gas diffusion electrode (2-1) is provided on the cathode tank (2), and a catalyst (2-2) is coated on the outer surface of the gas diffusion electrode (2-1); a hanging wall plate (2-4) is provided on the top of the cathode tank (2), and the hanging wall plate (2-4) is horizontally supported on the upper end surface of the anode tank (1); the aeration and stirring device (3) is composed of a diffuser. The invention is composed of a scattered gas chamber (3-1), an air pump (3-2) and a gas pipeline (3-3); the upper surface of the scattered gas chamber (3-1) is provided with a plurality of evenly distributed air holes (3-4); the scattered gas chamber (3-1) is located at the bottom surface of the inner cavity of the anode tank (1) and corresponds to the position of the cathode tank (2); the lower part of the scattered gas chamber (3-1) is connected to one end of the gas pipeline (3-3); the other end of the gas pipeline (3-3) extends from the anode tank (1) and is connected to the air pump (3-2); wherein the iron particle layer (1-1) and the gas diffusion electrode (2-1) are connected to the positive and negative electrodes of a power source through a circuit.

2. The novel hollow chamber gas diffusion electrode reactor according to claim 1 is characterized in that: The cathode slot (2) is a cylindrical structure with an opening at the top, and four square openings (2-3) of equal size are provided on the circumferential surface of the cathode slot (2). The gas diffusion electrode (2-1) with a catalyst (2-2) coated on the outer surface is a cylindrical structure of equal diameter and is located in the cathode slot (2), and each square opening (2-3) corresponds to the position of the iron particle layer (1-1) of the anode slot (1).

3. The novel hollow chamber gas diffusion electrode reactor according to claim 1, characterized in that: The scattered point air chamber (3-1) is in the form of a flat rectangular parallelepiped structure, with the side with a larger area located at the top.

4. The novel hollow chamber gas diffusion electrode reactor according to claim 1, characterized in that: The circuit comprises a DC power supply (4-1) and two bidirectional knife switches (4-2), wherein the output terminal of the upper knife switch is connected to the iron particle layer (1-1), and the output terminal of the lower knife switch is connected to the gas diffusion electrode (2-1), and four contacts are arranged on both sides of the bidirectional knife switch (4-2). When the upper and lower knife switches (4-2) are simultaneously connected to the contacts on the left, the gas diffusion electrode (2-1) is connected to the positive electrode of the DC power supply (4-1), and the iron particle layer (1-1) is connected to the negative electrode of the DC power supply (4-1); when the upper and lower knife switches (4-2) are simultaneously connected to the contacts on the right, the gas diffusion electrode (2-1) is connected to the negative electrode of the DC power supply (4-1), and the iron particle layer (1-1) is connected to the positive electrode of the DC power supply (4-1).

5. The novel hollow chamber gas diffusion electrode reactor according to claim 1, characterized in that: The upper surface of the anode tank (1) is provided with four grooves (1-2); the two hanging wall panels (2-4) on the upper part of the cathode tank (2) are arranged in parallel and are clamped in the corresponding grooves (1-2).

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