Electro-fenton device and method using oxygen evolution side reaction

Abstract

The application discloses an electro-Fenton device and method using an oxygen evolution side reaction, comprising a reaction container, a main anode, a main cathode and a porous carbon sensing electrode arranged in the reaction container; the main cathode and the porous carbon sensing electrode are annular, the porous carbon sensing electrode is arranged around the main anode, and the main cathode is arranged around the porous carbon sensing electrode; or, the main anode and the porous carbon sensing electrode are annular, the porous carbon sensing electrode is arranged around the main cathode, and the main anode is arranged around the porous carbon sensing electrode; the porous carbon sensing electrode is subjected to an electric field between the main anode and the main cathode, and the inner and outer peripheries of the porous carbon sensing electrode are respectively an induced anode / cathode and an induced cathode / anode. By arranging the sensing electrode, the mass transfer distance is shortened, the oxygen evolution side reaction of the anode in the traditional electro-Fenton reaction is fully utilized, the oxygen evolved is utilized by the cathode to participate in the oxygen reduction reaction, the Fenton reaction is promoted, and the main anode plays an electroflocculation role while corroding the anode under electrolysis to supplement the anions required by the reaction.

Description

Technical Field

[0001] This invention belongs to the field of advanced wastewater treatment technology, and relates to electro-Fenton and electrocoagulation treatment technologies, particularly to an electro-Fenton device and method utilizing the oxygen evolution side reaction. Background Technology

[0002] Electro-Fenton technology is an advanced oxidation technology that can efficiently degrade organic pollutants, including recalcitrant organic compounds such as pesticides, dyes, and organic solvents. It can break down harmful substances into harmless ones, thus significantly improving water quality. This technology has a wide range of applications and adaptability, suitable for various wastewater types and pollution levels. Whether it's industrial wastewater, domestic sewage, or even hospital wastewater and agricultural drainage, electro-Fenton technology can be effective. Furthermore, the treatment effect of electro-Fenton technology can be improved by adjusting operating conditions and electrode design. The electro-Fenton process can be optimized according to different wastewater characteristics and treatment needs to achieve the best treatment results. However, traditional electro-Fenton technology mainly relies on the cathode, using an inert anode that can only conduct electricity and produces an oxygen evolution side reaction, requiring the additional addition of ferrous ions to ensure the Fenton reaction proceeds. This results in additional energy consumption and resource waste, increases the operational complexity in practical engineering, and the oxygen released by the side reaction is hazardous in industrial applications such as oil and gas fields. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide an electro-Fenton device and method that utilizes the oxygen evolution side reaction. This method is mainly used to solve the problems of small anode effect and resource waste in traditional electro-Fenton devices. It makes full use of each part of the device to achieve the integration of electro-Fenton and electro-coagulation, while utilizing the oxygen generated by the side reaction to achieve the requirement of saving resources.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A first aspect of the present invention provides an electro-Fenton device utilizing the oxygen evolution side reaction, comprising a reaction vessel and a main anode, a main cathode and a porous carbon induction electrode disposed in the reaction vessel;

[0006] Wherein, the main cathode and the porous carbon sensing electrode are annular, the porous carbon sensing electrode is arranged around the main anode, and the main cathode is arranged around the porous carbon sensing electrode; or, the main anode and the porous carbon sensing electrode are annular, the porous carbon sensing electrode is arranged around the main cathode, and the main anode is arranged around the porous carbon sensing electrode;

[0007] The main anode is connected to the positive terminal of the power supply, and the main cathode is connected to the negative terminal of the power supply. Under the action of the electric field between the main anode and the main cathode, the inner and outer peripheries of the porous carbon induction electrode respectively serve as induction cathode and induction anode, or respectively serve as induction anode and induction cathode.

[0008] In one embodiment, the main anode is made of metal, and the main cathode is made of activated carbon fiber.

[0009] In one embodiment, the metal is iron; the activated carbon fiber has a BET specific surface area of ​​1500±300 m². 2 / g, Langmuir specific surface area 2000±250m² 2 / g, BJH adsorption average pore size 1.5±0.25nm; the specific surface area of ​​the porous carbon induction electrode is 1800±400m². 2 / g, pore size 1.5±0.5nm.

[0010] In one embodiment, the porous carbon sensing electrode is located between the main anode and the main cathode, with a radial thickness of 1.5 ± 0.5 cm, a radial distance of 5-10 cm between it and the main anode, and a radial distance of 5-10 cm between it and the main cathode.

[0011] In one embodiment, the main anode and the main cathode are at the same height, and the height of the porous carbon induction electrode is two-thirds of the height of the main anode.

[0012] In one embodiment, the reaction vessel has an inlet and an outlet for water to enter and exit from outside the outermost electrode; the height of the inlet is 2-3 cm higher than the highest point of the main cathode.

[0013] In one embodiment, a stirring device is provided at the bottom of the reaction vessel, and the main anode, main cathode and porous carbon induction electrode are mounted above the stirring device via a support.

[0014] A second aspect of the present invention also provides an electro-Fenton method utilizing the oxygen evolution reaction (OER), implemented based on the electro-Fenton apparatus utilizing the OER described in the first aspect. Wastewater to be treated is fed into the reaction vessel, a power source is connected, and electricity is applied to the main anode and main cathode. The main anode is corroded under electrolysis, replenishing the cations required for the reaction while simultaneously performing electrocoagulation. The main cathode continuously generates H₂O₂ through a two-electron oxygen reduction reaction, which in turn generates ·OH to oxidize organic matter. Oxygen is generated by the OER at the sensing anode of the porous carbon sensing electrode, and the oxygen permeates through the porous carbon sensing electrode, participating in the Fenton reaction with the cations generated at the sensing cathode and main anode.

[0015] In one embodiment, the hydraulic residence time in the reaction vessel is 0.5-2 hours.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. Make full use of the oxygen evolution side reaction, resulting in high resource utilization.

[0018] 2. Oxygen reduction reaction can occur at multiple electrodes, resulting in high oxidation efficiency.

[0019] 3. Achieve integrated electro-Fenton and electro-coagulation, enabling simultaneous removal of organic matter and suspended solids.

[0020] 4. In addition to its conductive function, the main anode can generate ferrous ions, eliminating the need for additional reagents.

[0021] Therefore, compared with the traditional electro-Fenton method, this invention solves the problems of small anode effect and oxygen evolution side reaction, while improving oxidation efficiency and having a certain removal effect on suspended solids, which is of great significance for ensuring the treatment effect of wastewater treatment process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram (front sectional view) of the structure of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of the present invention (top view, external power supply not shown). Detailed Implementation

[0024] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0025] like Figure 1 and Figure 2 As shown, an electro-Fenton device utilizing the oxygen evolution side reaction includes a necessary reaction vessel, and a main anode 1, a main cathode 2, and a porous carbon induction electrode 3 installed within the reaction vessel.

[0026] The key to this invention lies in arranging a porous carbon induction electrode 3 between the main anode 1 and the main cathode 2. To this end, this invention provides two structural forms as follows:

[0027] In structure one, the main cathode 2 and the porous carbon sensing electrode 3 are annular, with the porous carbon sensing electrode 3 surrounding the main anode 1, and the main cathode 2 surrounding the porous carbon sensing electrode 3. In this case, the main anode 1 can be cylindrical, annular, or other shapes. The main cathode 2 and the porous carbon sensing electrode 3 can be closed shapes with cross-sections of square, rectangular, circular, elliptical, polygonal, or other forms.

[0028] In this structure, the main anode 1 is connected to the positive terminal of the power supply, and the main cathode 2 is connected to the negative terminal of the power supply. After the power is turned on, an electric field is generated between the main anode 1 and the main cathode 2. Under the action of this electric field, the inner side of the porous carbon induction electrode 3 of its annular structure becomes the induction cathode, and the outer side becomes the induction anode.

[0029] In structure two, the main anode 1 and the porous carbon sensing electrode 3 are annular, with the porous carbon sensing electrode 3 surrounding the main cathode 2, and the main anode 1 surrounding the porous carbon sensing electrode 3. In this case, the main cathode 2 can be cylindrical, annular, or other shapes. The main anode 1 and the porous carbon sensing electrode 3 can be closed shapes with cross-sections of square, rectangular, circular, elliptical, polygonal, or other forms.

[0030] In this structure, the main anode 1 is connected to the positive terminal of the power supply, and the main cathode 2 is connected to the negative terminal of the power supply. After the power is turned on, an electric field is generated between the main anode 1 and the main cathode 2. Under the action of this electric field, the inner side of the porous carbon induction electrode 3 of its annular structure becomes the induction anode, and the outer side becomes the induction cathode.

[0031] The principle of the two structures described above in this invention is as follows:

[0032] Based on the traditional electro-Fenton principle, dissolved oxygen undergoes an oxygen reduction reaction on the surface of a suitable cathode material to produce H2O2. The generated H2O2 reacts with cations in the solution to produce strong oxidizing agents, hydroxyl radicals. The main anode 1 of this device is corroded under electrolysis, generating the cations required for the reaction and acting as an electrocoagulant. A ring-shaped porous carbon induction electrode 3, positioned between the main cathode 2 and the main anode 1, functions as an induction cathode (or induction anode) within an electric field, and an induction anode (or induction cathode) on the outer periphery. The porous carbon induction electrode 3 shortens the mass transfer distance between the cathode and anode. Furthermore, due to the porous structure facilitating gas generation and diffusion, the oxygen generated by the oxygen evolution side reaction at the induction anode can undergo an electro-Fenton reaction with the cations generated at the main anode 1 on the induction cathode.

[0033] In some embodiments of the present invention, the main anode 1 is made of metal, possessing good conductivity, chemical stability, and machinability, and is corroded under electrolysis to produce metal cations. For example, it is preferably iron, thereby being corroded under electrolysis to produce ferrous ions.

[0034] In some embodiments of the present invention, the main cathode 2 is made of activated carbon fiber. Activated carbon fiber, as a novel cathode material, has shown promising application prospects in electrochemical energy storage devices due to its unique physical and chemical properties. On the one hand, activated carbon fiber has a very high specific surface area, meaning that more active sites can be provided per unit volume or mass of material surface, thereby increasing the contact area with the electrolyte and improving the rate and efficiency of the electrochemical reaction. For example, the BET specific surface area of ​​the activated carbon fiber of the present invention is 1500 ± 300 m². 2 / g, Langmuir specific surface area 2000±250m² 2 / g, BJH adsorption average pore size is 1.5±0.25nm. On the other hand, activated carbon fiber has better conductivity than many traditional cathode materials, which helps to improve the electron transport efficiency inside the electrode and reduce energy loss. At the same time, activated carbon fiber has good chemical stability over a wide electrochemical window, which allows it to work stably in a variety of electrolyte environments, is not prone to decomposition or degradation, and helps to extend the battery's lifespan.

[0035] Porous carbon materials possess a highly developed pore structure, providing abundant surface area and numerous active sites. This allows for more reaction sites in electrochemical reactions, thereby enhancing their electrochemical activity and charge transport capabilities. Simultaneously, their excellent electrical conductivity enables efficient electron conduction, reducing the internal resistance of the electrode. In some embodiments of the present invention, the specific surface area of ​​the porous carbon induction electrode 3 is 1800 ± 400 m². 2 / g, pore size 1.5±0.5nm.

[0036] In some embodiments of the present invention, the porous carbon induction electrode 3 is located between the main anode 1 and the main cathode 2, and the three can be arranged in a concentric manner, typically as shown in... Figure 1 and Figure 2 The concentric circle shape is shown. By setting the porous carbon induction electrode 3, the mass transfer distance is shortened, and the oxygen evolution side reaction at the anode in the traditional electro-Fenton reaction is fully utilized, so that the evolved oxygen is used by the cathode to participate in the oxygen reduction reaction, thus promoting the Fenton reaction. To further ensure the effect, in this embodiment, the radial thickness of the porous carbon induction electrode 3 is set to 1.5±0.5cm, and its radial distance from the main anode 1 is in the range of 5-10cm, and its radial distance from the main cathode 2 is in the range of 5-10cm, satisfying the main electro-Fenton reaction conditions.

[0037] In some embodiments of the present invention, the axial direction of the annular shape is vertical. Furthermore, the main anode 1 and the main cathode 2 are at the same height, while the height of the porous carbon induction electrode 3 is two-thirds of the height of the main anode 1, thereby leaving space for scum to prevent it from affecting the efficiency of the induction electrode.

[0038] In some embodiments of the present invention, the reaction vessel has an inlet 5 and an outlet 6, through which water enters and exits from outside the outermost electrodes; the height of the inlet 5 is 2-3 cm higher than the highest point of the main cathode 2, ensuring that the water can submerge the main anode 1 and the main cathode 2, and the outlet 6 is 1-2 cm higher than the bottom of the reaction vessel, so as to facilitate water discharge.

[0039] In some embodiments of the present invention, a stirring device 7 is provided at the bottom of the reaction vessel. The function of the stirring device 7 is to promote the reaction. Its arrangement can be such that the bottom of the main anode 1, the main cathode 2, and the porous carbon induction electrode 3 are located at the bottom of the reaction vessel, and the stirring device 7 is arranged between adjacent electrodes and between the electrodes and the inner wall of the vessel. Alternatively, the stirring device 7 can be directly arranged at the bottom of the entire vessel or in the central part of the bottom of the vessel, and the main anode 1, the main cathode 2, and the porous carbon induction electrode 3 are arranged above the stirring device 7 by a support.

[0040] The electro-Fenton method for the oxygen evolution side reaction of the present invention, utilizing the above-described electro-Fenton device, is as follows:

[0041] The wastewater to be treated is fed into the reaction vessel through inlet 5. An external power source 4 is connected to provide the necessary electrical energy to the main anode 1 and main cathode 2. The main anode 1 is corroded under electrolysis, replenishing the cations required for the reaction while also playing an electrocoagulation role. The main cathode 2 continuously generates H2O2 through the oxygen reduction reaction of two electrons, which in turn generates ·OH free radicals. These highly active free radicals can further oxidize organic matter, achieving simultaneous removal of organic matter and suspended solids. The oxygen evolution side reaction occurs at the sensing anode of the porous carbon sensing electrode 3 to generate oxygen. The oxygen passes through the porous carbon sensing electrode 3 and participates in the Fenton reaction with the cations generated at the sensing cathode and main anode 1.

[0042] This invention is applicable to domestic sewage and industrial wastewater with high COD. This device can efficiently degrade organic pollutants, including recalcitrant organic compounds such as pesticides, dyes, and organic solvents. It can break down harmful substances into harmless ones, thereby significantly improving water quality. Generally, the hydraulic retention time in the reaction vessel can be controlled between 0.5 and 2 hours.

[0043] In summary, this invention, through the arrangement of the main anode 1, the main cathode 2, and the porous carbon sensing electrode 3, makes full use of the oxygen generated by the side reaction and combines it with the electro-Fenton and electrocoagulation reactions to achieve efficient removal of organic matter and simultaneous removal of suspended solids. It also makes full use of traditional electro-Fenton byproducts, thus realizing the rational utilization of resources.

Claims

1. An electro-Fenton device utilizing the oxygen evolution side reaction, characterized in that, The reaction vessel includes a main anode (1), a main cathode (2), and a porous carbon induction electrode (3) placed within it. The main anode (1) is made of iron, and the main cathode (2) is made of activated carbon fiber with a BET specific surface area of ​​1500 ± 300 m². 2 / g, Langmuir specific surface area 2000±250 m² 2 / g, BJH adsorption average pore size 1.5±0.25 nm; the specific surface area of ​​the porous carbon induction electrode (3) is 1800±400 m² / g. 2 / g, pore size 1.5±0.5 nm; Wherein, the main cathode (2) and the porous carbon sensing electrode (3) are annular, the porous carbon sensing electrode (3) is arranged around the main anode (1), and the main cathode (2) is arranged around the porous carbon sensing electrode (3); or, the main anode (1) and the porous carbon sensing electrode (3) are annular, the porous carbon sensing electrode (3) is arranged around the main cathode (2), and the main anode (1) is arranged around the porous carbon sensing electrode (3); the porous carbon sensing electrode (3) is located between the main anode (1) and the main cathode (2), its radial thickness is 1.5±0.5 cm, the radial distance between it and the main anode (1) is in the range of 5-10 cm, and the radial distance between it and the main cathode (2) is in the range of 5-10 cm; the main anode (1) and the main cathode (2) are at the same height, and the height of the porous carbon sensing electrode (3) is two-thirds of the height of the main anode (1); The main anode (1) is connected to the positive terminal of the power supply, the main cathode (2) is connected to the negative terminal of the power supply, and the porous carbon induction electrode (3) is in the form of an induction cathode and an induction anode respectively on the inner and outer peripheries under the action of the electric field between the main anode (1) and the main cathode (2), or in the form of an induction anode and an induction cathode respectively.

2. The electro-Fenton device utilizing the oxygen evolution side reaction according to claim 1, characterized in that, The reaction vessel has an inlet (5) and an outlet (6) for water to enter and exit from outside the outermost electrode; the height of the inlet (5) is 2-3 cm higher than the highest point of the main cathode (2).

3. The electro-Fenton device utilizing the oxygen evolution side reaction according to claim 1, characterized in that, A stirring device (7) is provided at the bottom of the reaction vessel, and the main anode (1), main cathode (2) and porous carbon induction electrode (3) are mounted above the stirring device (7) by a support.

4. An electro-Fenton method utilizing the oxygen evolution reaction (OER), implemented using the electro-Fenton apparatus according to any one of claims 1 to 3, characterized in that, The wastewater to be treated is fed into the reaction vessel, and the power supply (4) is turned on to apply electricity to the main anode (1) and the main cathode (2). The main anode (1) is corroded under electrolysis, and while replenishing the cations required for the reaction, it also plays an electrocoagulation role. The main cathode (2) continuously generates H2O2 through the oxygen reduction reaction of two electrons, and then generates ·OH to oxidize organic matter. The oxygen evolution side reaction occurs at the sensing anode of the porous carbon sensing electrode (3) to generate oxygen. The oxygen passes through the porous carbon sensing electrode (3) and participates in the Fenton reaction with the cations generated by the sensing cathode and the main anode (1).

5. The electro-Fenton method utilizing the oxygen evolution side reaction according to claim 4, characterized in that, The hydraulic residence time in the reaction vessel is 0.5-2 h.

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