Electro-fenton reactor and method for treating pollutants using the same

Abstract

The application discloses an electro-Fenton reactor and a method for treating pollutants, and relates to the technical field of waste treatment. The electro-Fenton reactor comprises a barrel body with a water inlet and a water outlet on two sides; the barrel body is provided with gas outlets on the upper and lower sides; at least two composite electrodes are arranged in the barrel body; the composite electrode located on the upper side is a cathode, and the composite electrode located on the lower side is an anode; the barrel body can be turned over to alternately use the composite electrodes; an air inlet pipe is coaxially arranged with the water inlet and penetrates into the barrel body at one end; at least two iron electrodes are arranged; and a sealing plug is arranged in the gas outlet. + The application adjusts the cathode, which is caused by fouling and makes the electro-Fenton performance decline, to be an anode by using a reverse electrode method, the anode oxidizes water to generate H The application reduces the pH, thereby removing the fouling on the surface of the catalyst. When the electro-Fenton reactor is used for waste gas purification, the volatile organic compounds VOCs in the gas can be oxidized without changing the cathode and the anode, thereby obtaining the function of effectively purifying the waste gas.

Description

Technical Field

[0001] This invention relates to the field of waste treatment technology, and in particular to an electric Fenton reactor and a method for treating pollutants thereon. Background Technology

[0002] With rapid urban development, some wastewater is extremely difficult to degrade, such as wastewater containing antibiotics, dyeing and printing wastewater, and high COD wastewater. These are usually treated by advanced water oxidation through electrochemical methods, which are widely used and do not generate additional waste.

[0003] Currently, electrochemical methods are mainly divided into two types. One type oxidizes water directly at the anode or through free radical oxidation at the anode. This application requires anode materials with high oxygen evolution overpotential and corrosion resistance at high potentials. Commonly used BDD electrodes meet these requirements but are expensive; Ti4O7 electrodes are mostly still in the laboratory stage, and large-area electrodes are not yet available on the market. The other type oxidizes water by generating hydrogen peroxide at the cathode, followed by a Fenton reaction to produce free radicals, i.e., the electro-Fenton reaction. The electro-Fenton reaction at the cathode increases the pH, leading to scaling and a decrease in reaction efficiency. Therefore, electrochemical methods have the following drawbacks: 1. The efficiency of single-electrode reactions needs improvement. For example, during anodic oxidation, hydrogen evolution may occur at the cathode, and the cathode reaction does not contribute to wastewater oxidation. Similarly, during the electro-Fenton reaction at the cathode, oxygen evolution may occur at the anode, which also does not contribute to wastewater oxidation. 2. Scaling problems at the electro-Fenton cathode. Scale buildup on the cathode surface can reduce the active sites of the catalyst and decrease electrode performance. 3. High cost of corrosion-resistant anodes.

[0004] In summary, how to solve the problem of cathode scaling in electro-Fenton reactors, meet the requirements of low anode cost, high oxygen evolution potential and corrosion resistance, and have a structure that can be used for both wastewater treatment and exhaust gas purification has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an electric Fenton reactor, system, and control method to address the deficiencies mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides an electro-Fenton reactor, the electro-Fenton reactor comprising:

[0007] A cylindrical body with water inlets and outlets on both sides; air outlets on both the upper and lower sides of the cylindrical body; at least two composite electrodes are provided inside the cylindrical body;

[0008] The composite electrode located at the top is the cathode, and the composite electrode located at the bottom is the anode; the cylinder can be flipped to alternately use the composite electrodes;

[0009] An air inlet pipe is coaxially arranged with the water inlet and one end of it passes into the cylinder body;

[0010] At least two iron electrodes are located on the side away from the axis of the cylinder and are respectively arranged corresponding to the composite electrode; the iron electrode is also called the Fenton catalytic electrode; the upper iron electrode is in contact with the top surface of the corresponding composite electrode, and the lower iron electrode is separated from the corresponding composite electrode;

[0011] A sealing plug is disposed inside the air outlet to seal each of the air outlets below the cylinder.

[0012] Preferably, when the electro-Fenton reactor is used for wastewater treatment, the inlet is used to feed wastewater into the cylinder, the air inlet is used to input air into the cylinder, and the composite electrode is used alternately by flipping the cylinder during the treatment process.

[0013] Preferably, when the electro-Fenton reactor is used to purify waste gas, the water inlet is used to supply conductive but non-scaling water into the cylinder, and the air inlet is used to introduce waste gas into the cylinder.

[0014] Preferably, the composite electrode comprises:

[0015] A conductive substrate, a catalytic layer, and a hydrophobic layer are sequentially arranged; wherein, the catalytic layer is composed of conductive micro / nano particles, graphene structure, and hydrophobic polymer; the hydrophobic layer partially covers the catalytic layer, the hydrophobic layer is located on the side closer to the axis of the cylinder, and the conductive substrate is located on the side away from the axis of the cylinder.

[0016] Preferably, the conductive substrate, the catalyst layer, and the hydrophobic layer all have vent holes to allow gas to float upwards through the vent holes to the gas outlet.

[0017] Preferably, the conductive micro / nanoparticles include at least one of Ti4O7, boron-doped diamond, titanium carbide, titanium nitride, and boron-doped silicon carbide.

[0018] Preferably, the graphene structure is graphene or a mixture of graphene; the graphene mixture is composed of graphene and a portion of graphene oxide.

[0019] Preferably, a guide ring is fixedly connected to the outer side of the cylinder, and at least two first positioning rollers and at least two second positioning rollers are in rolling contact inside the guide ring. The first positioning rollers are located below the second positioning rollers. The first positioning rollers and the second positioning rollers are rotatably connected to the bracket via a rotating shaft. The first positioning rollers are electrically connected to the composite electrode located below, and the second positioning rollers are electrically connected to the composite electrode located above. A flipping drive component is installed on the outer side of the cylinder.

[0020] Preferably, the flipping drive component:

[0021] A toothed ring is fixedly connected to the outside of the cylinder, the toothed ring meshes with a drive gear, the drive gear shaft is connected to a drive motor, and the drive motor is mounted on the bracket;

[0022] The guide ring is embedded with multiple conductive blocks, which are electrically connected to the corresponding composite electrodes via connecting wires. The first positioning roller is in conductive contact with the conductive block located below, and the second positioning roller is in conductive contact with the conductive block located above. The first positioning roller and the second positioning roller are insulated from the guide ring and the bracket.

[0023] A method for treating pollutants using an electric Fenton reactor, the method comprising:

[0024] The upper composite electrode is connected to the negative electrode, and the lower composite electrode is connected to the positive electrode;

[0025] During wastewater treatment, after a certain reaction time, the cylinder is flipped over, keeping the upper composite electrode connected to the negative electrode and the lower composite electrode connected to the positive electrode, and the treatment continues.

[0026] During waste gas treatment, the cylinder does not rotate and continues to process the waste gas.

[0027] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0028] This invention discloses an electro-Fenton reactor, system, and control method. The reactor includes a cylindrical body with inlets and outlets on both sides, at least two composite electrodes, an air inlet pipe, at least two iron electrodes, and multiple sealing plugs. The composite electrodes are arranged on a support mesh inside the cylindrical body. When the electro-Fenton reactor is used for wastewater treatment, the composite electrodes in the reactor simultaneously function as cathodes and anodes, significantly improving the electrochemical reaction efficiency of wastewater degradation. Furthermore, this invention employs a rotating electrode reversal method, adjusting the cathode, whose electro-Fenton performance is degraded due to scaling, to become the anode by rotating the cylindrical body. The anode oxidizes water to produce H₂. + The pH is lowered, thereby removing scale from the catalyst surface. When the electro-Fenton reactor is used for waste gas purification, there is no need to change the anode and cathode; volatile organic compounds (VOCs) in the gas can be oxidized, thus effectively purifying the waste gas. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the electro-Fenton reactor according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the electro-Fenton reactor after the cylinder is removed, according to an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the cross-sectional structure in the main view direction according to an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the cross-sectional structure in a side view according to an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of the composite electrode structure according to an embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram of the structure of the guide ring, the first positioning roller, and the second positioning roller in an embodiment of the present invention.

[0036] The components include: 1. Cylinder; 101. Toothed ring; 102. Guide ring; 103. Conductive block; 104. Connecting wire; 2. Support mesh; 201. Anti-detachment frame; 3. Composite electrode; 31. Conductive substrate; 32. Catalytic layer; 33. Hydrophobic layer; 4. Iron electrode; 5. Water inlet; 6. Water outlet; 7. Air inlet pipe; 701. Aeration plate; 8. Air outlet; 9. Sealing plug; 10. Cathode; 11. Anode; 12. Support; 1201. Drive motor; 1202. Drive gear; 1203. First positioning roller; 1204. Second positioning roller; 13. Vent hole. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The purpose of this invention is to provide an electric Fenton reactor, system, and control method to address the deficiencies mentioned in the background art.

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] like Figure 1-2 As shown, this invention discloses an electro-Fenton reactor, which includes:

[0041] A cylindrical body 1 has a water inlet 5 and a water outlet 6 on both sides; the upper and lower sides of the cylindrical body 1 have air outlets 8; at least two composite electrodes 3 are installed inside the cylindrical body.

[0042] The upper composite electrode 3 is the cathode 10, and the lower composite electrode 3 is the anode 11; the cylinder 1 can be flipped to alternately use the composite electrode 3;

[0043] An air inlet pipe (7) is coaxially arranged with the water inlet (5) and one end of it is inserted into the cylinder (1);

[0044] At least two iron electrodes 4 are located on the side away from the axis of the cylinder 1 and are respectively set with the composite electrode 3; the iron electrode is also called the Fenton catalytic electrode; the iron electrode 4 located above is in contact with the top surface of the corresponding composite electrode 3, and the iron electrode 4 located below is separated from the corresponding composite electrode 3.

[0045] A sealing plug 9 is located inside the air outlet 8 to seal each air outlet 8 at the bottom of the cylinder 1. A water inlet 5 is used to input wastewater into the cylinder 1, and a water outlet 6 is used to discharge the degraded wastewater from the cylinder 1. Due to gravity, each air outlet 8 at the top of the cylinder 1 separates from the sealing plug 9, while each air outlet 8 at the bottom of the cylinder 1 is sealed to the sealing plug 9 by gravity and water pressure. Two support nets 2 are installed inside the cylinder 1, and multiple composite electrodes 3 are mounted on the support nets 2 inside the cylinder 1. An air inlet pipe 7 is used to introduce air or waste gas into the cylinder 1. After entering through the air inlet pipe 7, the gas rises, generating hydrogen peroxide on the surface of the upper composite electrode 3. The hydrogen peroxide reacts with the iron electrode 4 to undergo an electro-Fenton reaction, and the gas is finally discharged through each air outlet 8 at the top of the cylinder 1.

[0046] When the electro-Fenton reactor is used for waste gas purification, inlet 5 supplies conductive, non-scaling water into the cylinder 1, and inlet 7 introduces waste gas into the cylinder 1. The volatile organic compounds (VOCs) in the waste gas are then oxidized, and pathogens are treated, resulting in purification. The entire process does not require anode / cathode switching. Application scenarios include hospitals, hotels, shopping malls, factories, and other places requiring air purification. For example, some factories emit odorous exhaust gases; passing these gases into this reactor can achieve purification.

[0047] When the electro-Fenton reactor is used for wastewater treatment, the inlet 5 is used to feed wastewater into the cylinder 1, and the air inlet 7 is used to input air. After a certain period of operation, the performance of the reactor cathode 10 may deteriorate due to scaling. At this time, the reactor cylinder 1 is rotated to alternately change the anode and cathode, always keeping the composite electrode 3 located at the top as the cathode 10 and the composite electrode 3 located at the bottom as the anode 11 (that is, the composite electrode 3 that was originally the cathode 10 is changed to the anode 11, and the composite electrode 3 that was originally the anode 11 is changed to the cathode 10). When the position of the composite electrode 3 is changed, the iron electrode 4 that was originally located above the cathode 10 is now located below the anode 11. The iron electrode 4 is detached from the anode 11 due to its own weight, avoiding corrosion at the anode 11. There are gas outlets 8 at the top and bottom of the reactor cylinder 1, and the gas outlets 8 are sealed with plugs 9, which can be conical. The sealing plug 9 of the top air outlet 8 sinks under the action of gravity, creating an exhaust channel; the sealing plug 9 of the bottom air outlet 8 closes under the action of water pressure; the wastewater outlet remains unchanged when the reactor rotates.

[0048] The composite electrode 3 of this invention can be fixed to the support mesh 2 by means of sewing or other methods. Specifically, the hydrophobic layer 33 is in contact with the support mesh 2, and the conductive substrate 31 is in contact with the iron electrode 4. In this invention, the composite electrode 3 is fixed to the support mesh 2 by means of sewing or other methods. An anti-detachment frame 201 is fixedly connected to the side of the support mesh 2 away from the axis of the cylinder 1. The iron electrode 4 is movably disposed inside the anti-detachment frame 201, the purpose of which is to keep the electrode position stable during polarity reversal.

[0049] The cathode 10 and anode 11 of the electro-Fenton reactor of the present invention both adopt the above-mentioned composite electrode 3. One side of the composite electrode 3 is hydrophobic and the other side is conductive. The above-mentioned composite electrode 3 is perforated to form an upper and lower connected structure. The vent hole facilitates the passage of the floating gas and promotes the contact between the hydrogen peroxide generated on the cathode 10 and the iron electrode 4.

[0050] The conductive substrate 31 of the present invention can be made of at least one of graphite paper or carbon fiber cloth. When graphite paper is used as the conductive substrate 31, if the strength is insufficient, it can be reinforced by setting a rigid support structure, such as a mesh structure.

[0051] like Figure 5 As shown, the composite electrode 3 includes:

[0052] A conductive substrate 31, a catalyst layer 32, and a hydrophobic layer 33 are sequentially arranged. The catalyst layer 32 is composed of conductive micro / nano particles, graphene structure, and hydrophobic polymer. The hydrophobic layer 33 partially covers the catalyst layer 32 and is located on the side closer to the axis of the cylinder 1. The conductive substrate 31 is located on the side away from the axis of the cylinder 1.

[0053] In a further optimized design, the conductive substrate 31, the catalyst layer 32, and the hydrophobic layer 33 all have vent holes 13, so that the gas can float upward to the outlet 8 through the vent holes 13.

[0054] Further optimization of the scheme involves conductive micro / nano particles, including at least one of Ti4O7, boron-doped diamond, titanium carbide, titanium nitride, and boron-doped silicon carbide, which possess both corrosion resistance and conductivity. The graphene structure is graphene or a mixture of graphene; the graphene mixture consists of graphene and partially graphene oxide. The hydrophobic polymer is made using a PTFE emulsion. The hydrophobic layer 33 is generated by screen printing a PTFE emulsion onto the surface of the catalyst layer 32 followed by heat treatment, and thus possesses hydrophobic properties.

[0055] The iron electrode 4 of this invention, also known as the Fenton catalytic electrode, can be made of wire mesh, foamed iron, or porous material loaded with iron components. The corresponding iron electrode 4 structure can be selected according to actual needs.

[0056] When the electro-Fenton reactor disclosed in this invention is used for wastewater treatment,

[0057] A guide ring 102 is fixedly connected to the outside of the cylinder 1. At least two first positioning rollers 1203 and at least two second positioning rollers 1204 are in rolling contact inside the guide ring 102. The first positioning rollers 1203 are located below the second positioning rollers 1204. The first positioning rollers 1203 and the second positioning rollers 1204 are rotatably connected to the bracket 12 via a rotating shaft. The first positioning rollers 1203 are electrically connected to the composite electrode 3 located below, and the second positioning rollers 1204 are electrically connected to the composite electrode 3 located above. A flipping drive component is installed on the outside of the cylinder 1.

[0058] Further optimization of the solution, including the flip drive component:

[0059] A toothed ring 101 is fixedly connected to the outside of the cylinder 1. The toothed ring 101 meshes with a drive gear 1202. The drive gear 1202 is shaft-connected to a drive motor 1201. The drive motor 1201 is mounted on the bracket 12.

[0060] Multiple conductive blocks 103 are embedded in the guide ring 102. The conductive blocks 103 are electrically connected to the corresponding composite electrodes 3 through connecting wires 104. The first positioning roller 1203 is in conductive contact with the conductive block 103 located below, and the second positioning roller 1204 is in conductive contact with the conductive block 103 located above. The first positioning roller 1203 and the second positioning roller 1204 are insulated from the guide ring 102 and the bracket 12.

[0061] With this configuration, when the cylinder 1 is flipped, the drive motor 1201 is controlled to rotate. The meshing of the drive gear 1202 and the gear ring 101 allows the cylinder 1 to rotate 180 degrees. The cooperation between the guide ring 102 and the first positioning roller 1203 and the second positioning roller 1204 ensures the normal rotation of the cylinder 1. The shafts of the first positioning roller 1203 and the second positioning roller 1204 are connected to their corresponding positive and negative poles. The shafts are fixed and rotatably connected to the first positioning roller 1203 and the second positioning roller 1204. The shafts are mounted on the bracket 12 and insulated from it. This ensures that the composite electrode 3 is de-energized during the rotation of the cylinder 1. After the cylinder 1 is flipped to its correct position, the corresponding conductive block 103 also rotates to its corresponding position, thus ensuring that the composite electrode 3 inside the cylinder 1 is always the cathode 10 after the cylinder 1 is flipped.

[0062] The air inlet pipe 7 of the present invention is connected to an aeration plate 701 inside the cylinder 1. The aeration plate 701 has a hollow structure and several aeration holes are opened on the upper and lower end faces of the aeration plate 701.

[0063] In this invention, the air inlet pipe 7 and the water inlet 5 are coaxially arranged. The air inlet pipe 7 and the water inlet 5 can be fixedly installed on the bracket 12 or on the ground by a mounting rod. The end of the water inlet 5 away from the air inlet pipe 7 is closed to the air inlet pipe 7. A pipe body (not shown in the figure) is connected to the side wall of the water inlet, which can realize the function of air and liquid intake without affecting the rotation of the cylinder 1. When the cylinder 1 rotates, it does not affect the gas intake of the air inlet pipe 7. In this invention, the water inlet 5 and the cylinder 1 are preferably connected by a sealed bearing. That is to say, the water inlet 5 remains in the same position when the reactor cylinder 1 rotates. The above is only one embodiment, and other connection methods can also be used.

[0064] Unlike traditional reactors that use vertical electrodes, the reactor disclosed in this invention has its cathode 10 and anode 11 placed horizontally at the top and bottom of the reactor, respectively. An air inlet pipe 7 connects the two composite electrodes 3. Air bubbles introduced through the air inlet pipe 7 rise to the cathode 10 region and undergo an electroreduction reaction to generate hydrogen peroxide. The hydrogen peroxide then reacts with the adjacent iron electrode 4 of the composite electrode 3 to generate Fenton's reagent. This invention's horizontal electrode placement not only facilitates the passage of rising air bubbles through the vent holes 13 of the cathode 10, thereby improving oxygen utilization, but also ensures that the iron electrode 4 maintains electrical contact with the cathode 10 and electrical disconnection from the anode 11 under the influence of gravity and water pressure.

[0065] Taking Ti4O7 as an example of conductive micro / nano particles, graphene as the graphene structure, and PTFE emulsion as the hydrophobic polymer, the preparation method is as follows: Ti4O7 powder, graphene, and PTFE emulsion are ball-milled and coated onto graphite paper. PTFE acts as a binder and provides localized hydrophobicity. Graphene oxide adheres to the Ti4O7 surface during ball milling and can be partially converted into graphite. The slurry is coated onto the graphite paper and hot-pressed (carbon nanotubes or other catalytic components can also be added to the slurry), providing bonding strength and offering good electron channels for Ti4O7. PTFE emulsion is screen-printed onto the surface of the catalyst layer 32 and further heat-treated to produce hydrophobicity. The composite layer is perforated to form an upper and lower vent structure, which is the composite electrode 3. One side of the composite electrode 3 is hydrophobic but non-conductive, while the other side is conductive but not hydrophobic. Conductivity allows the iron electrode 4 to contact the composite electrode 3 for use as a dual cathode 10, while hydrophobicity ensures oxygen adsorption and further reduction. The conductive side may gradually corrode when used as the anode 11. Alternatively, a catalyst layer 32 can be coated on both sides of the conductive substrate 31, and a slurry of PTFE and conductive carbon material can be coated onto the catalyst layer surface, followed by hot pressing. This results in both sides having a certain degree of hydrophobicity and conductivity. Coating both sides with the catalyst layer 32 increases corrosion resistance compared to coating only one side.

[0066] During use, the anode 11 undergoes an oxidation reaction, generating free radicals and directly oxidizing recalcitrant organic matter on the electrode. Below the cathode 10 is an air inlet pipe 7, where gas rises and, passing through a hydrophobic surface, is catalyzed by graphene in the catalyst layer 32 to produce hydrogen peroxide. This hydrogen peroxide then contacts the iron electrode 4, triggering an electro-Fenton reaction, oxidizing the iron electrode and generating free radicals. The iron electrode 4 then contacts the graphite paper, and the oxidized surface can be reduced. Since the reduction process on the cathode 10 leads to pH elevation and scaling, reducing electrode performance, the cathode 10 can be reversed to become the anode 11. The Ti4O7 and graphene in the anode 11 are corrosion-resistant, and in the acidic environment generated by the anode 11, scaling can be dissolved, allowing the electrode to be reused for the electro-Fenton reaction on the cathode 10.

[0067] Since the iron electrode 4 on the anode 11 can be oxidized, the iron electrode 4 on the anode 11 must be detached from the anode 11 (at this time, the iron electrode 4 will no longer be energized after being detached from the anode 11), which can be achieved by gravity.

[0068] To solve the scaling problem of cathode 10, this invention employs an electrode reversal method, adjusting cathode 10, whose electro-Fenton performance has decreased due to scaling, to anode 11. Anode 11 oxidizes water to produce H+, which lowers the pH near the electrode, thereby removing the scaling on the catalyst surface.

[0069] To address the high cost of corrosion-resistant electrodes, this invention utilizes inexpensive conductive materials such as graphite paper and carbon fiber cloth as a substrate. Ti4O7, graphene, and PTFE emulsions are ground and coated onto the substrate, followed by hot pressing. In this electrode, Ti4O7 enhances the oxygen evolution overpotential and corrosion resistance, graphene catalyzes oxygen reduction and also exhibits corrosion resistance, and PTFE provides hydrophobicity for oxygen adsorption. This low-cost electrode can be used simultaneously for both cathode 10 and anode 11, supporting descaling during electrode reversal.

[0070] Compared to reactions occurring on a single electrode, this invention's electro-Fenton reactor simultaneously functions as both a cathode (10) and an anode (11). The anode must possess a certain degree of oxidation resistance and a high oxygen evolution potential to generate free radicals under high voltage. The cathode can generate hydrogen peroxide, which further generates Fenton reagents. With both the anode and cathode functioning simultaneously, the electrochemical reaction efficiency for wastewater degradation is significantly improved.

[0071] Furthermore, this invention also discloses an electro-Fenton reaction control system for wastewater treatment. The system includes: the aforementioned electro-Fenton reactor, a power supply, an output polarity conversion circuit, and a controller. The output polarity conversion circuit is connected to both the power supply and the composite electrode 3, and the controller is connected to the output polarity conversion circuit. The wastewater treatment electro-Fenton reactor is used to degrade wastewater; the power supply is used to provide electrical energy; the output polarity conversion circuit is used to control the upper composite electrode 3 to always be the cathode and the lower composite electrode 3 to always be the anode 11, achieving anode-cathode reversal. In this embodiment, the output polarity conversion circuit is a full-bridge inverter circuit composed of four switching transistors, capacitors, inductors, etc., and various improved circuits. By controlling the on-time and off-time of the switches, the output voltage polarity of the output polarity conversion circuit can be changed. The specific structure is not discussed in detail here.

[0072] The system of this invention also includes: a sensing sensor connected to the controller, used to sense the rotational position of the cylinder 1 and send the signal to the controller, so that the controller can determine whether a set position has been reached. If the set position is reached, the controller will then control the output polarity conversion circuit to change the polarity of each composite electrode 3. The sensing sensor mentioned in this embodiment can be an infrared transmitter and an infrared receiver. The infrared receiver is set at a certain position on the cylinder 1, and the infrared transmitter is set at a fixed position. When the cylinder 1 rotates to the position corresponding to the infrared transmitter, the infrared receiver will receive an infrared signal and send it to the controller, so that the controller can control the switch to open and close according to the received signal, thereby realizing the anode-cathode conversion of the composite electrode 3. Alternatively, the infrared transmitter can be set at a certain position on the cylinder 1, and the infrared receiver can be set at a fixed position. When the cylinder 1 rotates to the position corresponding to the infrared receiver, the infrared receiver will receive an infrared signal and send it to the controller, so that the controller can control the switch to open and close according to the received signal, thereby realizing the anode-cathode conversion of the composite electrode 3. The sensing sensor can also be equipped with a distance measuring sensor, which is installed on the cylinder 1 and located between the two air outlets 8. When the controller determines that the distance between the distance measuring sensor and the ground is at its minimum, it means that the cylinder 1 has rotated halfway. At this time, the control switch is turned on and off, thereby realizing the anode-cathode conversion of the composite electrode 3. The above is merely an example and does not limit this application.

[0073] Furthermore, the present invention also discloses an electro-Fenton reaction control method for wastewater treatment, the method being used to control the above-mentioned system, the method comprising:

[0074] Turn on the power, close the first and second switches of the output polarity conversion circuit, and open the third and fourth switches so that the upper composite electrode 3 becomes the cathode 10 and the lower composite electrode 3 becomes the anode 11. Then control the cylinder 1 to flow wastewater.

[0075] After a period of time, control the cylinder 1 to rotate. When the cylinder 1 rotates to the set position, disconnect the first and second switches, and close the third and fourth switches so that the upper composite electrode 3 becomes the cathode 10 and the lower composite electrode 3 becomes the anode 11.

[0076] Experimental comparison:

[0077] 1. Anode performance: Anode with an area of ​​12cm² is used. 2 A composite electrode was used as the anode, and a Pt sheet electrode as the cathode. 500 mL of a Rhodamine B (RhB) solution with an initial concentration of 200 mg / L was used as the simulated wastewater (containing Fe). 2+ At a concentration of 1 mM, Ca 2+ (Concentration 100 mg / L), pH adjusted to 3, current density 14 mA / cm² 2 After 20 minutes of power-on, the COD removal rate was 35%.

[0078] 2. Cathode performance: A cathode with an area of ​​12cm² is used. 2 A composite electrode was used as the cathode, and a Pt sheet electrode as the anode. 500 mL of a Rhodamine B (RhB) solution with an initial concentration of 200 mg / L was used as the simulated wastewater (containing Fe). 2+ At a concentration of 1 mM, Ca 2+ (Concentration 100 mg / L), adjust pH to 3, aerate the solution, and apply a current density of 14 mA / cm². 2 After 20 minutes of power-on, the COD removal rate was 62%.

[0079] 3. The reactor of this invention: A composite electrode with an area of ​​12 cm² is used as the cathode and anode, and 500 mL of Rhodamine B (RhB) solution with an initial concentration of 200 mg / L is used as the simulated wastewater. 2+ Concentration 100 mg / L, Fe-free 2+ The pH is neutral, and the current density is 14 mA / cm². 2 After 20 minutes of power-on, the COD removal rate was 90%.

[0080] 4. Electrode stability: Under the conditions described in point 2, the cathode performance decreased after 5 cycles. Using the reactor and reversal method of this invention, after a continuous reaction of 240 hours and 10 reversals, the electrochemical performance remained essentially unchanged.

[0081] 5. Wastewater biodegradability: The BOD5 / COD ratio of RhB wastewater increased from 0.2 to 0.35; the BOD5 / COD ratio of antibiotic SMZ wastewater increased from 0.06 to 0.45.

[0082] 6. Treatment of toluene-containing waste gas: at 1m 3 The container was prepared with a toluene content of 400 mg / m³. 3 Simulated waste gas was pumped into the reactor inlet of this invention at a rate of 2 L / min using a gas pump, and the outlet was connected to a container to achieve a closed-loop circulation. The reactor had a volume of 600 mL and contained 500 mL of solution with a pH of 3. After 10 hours of treatment, the toluene content in the waste gas was determined by gas chromatography to be 10 mg / mL. 3 This indicates that the toluene removal rate reached 97.5%.

[0083] The above experiments demonstrate that the reactor disclosed in this invention not only maintains essentially the same electrochemical performance but also improves the COD removal rate compared to a single electrode. This reactor can be used for both wastewater and waste gas treatment.

[0084] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0085] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An electro-Fenton reactor, characterized in that, The electro-Fenton reactor includes: A cylindrical body (1) has a water inlet (5) and a water outlet (6) on both sides; the cylindrical body (1) has an air outlet (8) on both the upper and lower sides; at least two composite electrodes (3) are provided inside the cylindrical body. The composite electrode (3) located at the top is the cathode (10), and the composite electrode (3) located at the bottom is the anode (11); the cylinder (1) can be flipped to alternately use the composite electrode (3). An air inlet pipe (7) is coaxially arranged with the water inlet (5) and one end of it is inserted into the cylinder (1); At least two iron electrodes (4) are located on the side away from the axis of the cylinder (1) and are respectively arranged corresponding to the composite electrode (3); the iron electrode is also called the Fenton catalytic electrode; the upper iron electrode (4) is in contact with the top surface of the corresponding composite electrode (3), and the lower iron electrode (4) is separated from the corresponding composite electrode (3); A sealing plug (9) is provided inside the air outlet (8) to seal each of the air outlets (8) below the cylinder (1).

2. The electro-Fenton reactor according to claim 1, characterized in that, The composite electrode (3) includes: A conductive substrate (31), a catalyst layer (32), and a hydrophobic layer (33) are sequentially arranged; wherein, the catalyst layer (32) is composed of conductive micro-nano particles, graphene structure, and hydrophobic polymer; the hydrophobic layer (33) partially covers the catalyst layer (32), the hydrophobic layer (33) is located on the side close to the axis of the cylinder (1), and the conductive substrate (31) is located on the side away from the axis of the cylinder (1).

3. The electro-Fenton reactor according to claim 2, characterized in that, The conductive substrate (31), the catalyst layer (32) and the hydrophobic layer (33) all have vent holes (13) so that gas can float upward to the outlet (8) through the vent holes (13).

4. The electro-Fenton reactor according to claim 2, characterized in that, The conductive micro / nanoparticles include at least one of Ti4O7, boron-doped diamond, titanium carbide, titanium nitride, and boron-doped silicon carbide.

5. The electro-Fenton reactor according to claim 2, characterized in that, The graphene structure is graphene or a mixture of graphene; the graphene mixture is composed of graphene and a portion of graphene oxide.

6. The electro-Fenton reactor according to claim 1, characterized in that, A guide ring (102) is fixedly connected to the outside of the cylinder (1). At least two first positioning rollers (1203) and at least two second positioning rollers (1204) are rolling in contact inside the guide ring (102). The first positioning rollers (1203) are located below the second positioning rollers (1204). The first positioning rollers (1203) and the second positioning rollers (1204) are rotatably connected to the bracket (12) through a rotating shaft. The first positioning rollers (1203) are electrically connected to the composite electrode (3) located below, and the second positioning rollers (1204) are electrically connected to the composite electrode (3) located above. A flipping drive component is installed on the outside of the cylinder (1).

7. The electro-Fenton reactor according to claim 6, characterized in that, The flipping drive component: A toothed ring (101) is fixedly connected to the outside of the cylinder (1). The toothed ring (101) is meshed with a drive gear (1202). The drive gear (1202) is shaft-connected to a drive motor (1201). The drive motor (1201) is mounted on the bracket (12). The guide ring (102) is embedded with a plurality of conductive blocks (103). The conductive blocks (103) are electrically connected to the corresponding composite electrode (3) through connecting wires (104). The first positioning roller (1203) is in conductive contact with the conductive block (103) located below, and the second positioning roller (1204) is in conductive contact with the conductive block (103) located above. The first positioning roller (1203) and the second positioning roller (1204) are insulated from the guide ring (102) and the bracket (12).

8. A method for treating pollutants using an electro-Fenton reactor, characterized in that, The method utilizes the electro-Fenton reactor according to any one of claims 1-7, and the method comprises: The upper composite electrode (3) is connected to the negative electrode, and the lower composite electrode (3) is connected to the positive electrode; When the electric Fenton reactor is treating wastewater, the inlet (5) is used to send wastewater into the cylinder (1), and the air inlet (7) is used to input air into the cylinder (1). After a certain reaction time, the cylinder (1) is flipped, keeping the composite electrode (3) at the top connected to the negative electrode and the composite electrode (3) at the bottom connected to the positive electrode, and the treatment continues. When the electric Fenton reactor is treating waste gas, the inlet (5) is used to send conductive but non-scaling water into the cylinder (1), and the air inlet (7) is used to introduce waste gas into the cylinder (1). The cylinder (1) is not flipped and the treatment continues.

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