Electro-Fenton reactor and pollutant treatment method thereof

Abstract

The invention discloses an electro-Fenton reactor and a pollutant treatment method thereof, and relates to the technical field of waste treatment, the electro-Fenton reactor comprises: a cylinder having a water inlet and a water outlet at two sides; air outlets are formed in the upper and lower sides of the barrel; at least two composite electrodes are arranged in the cylinder body; the upper composite electrode is a cathode, and the lower composite electrode is an anode; the cylinder body can be turned over to alternately use the composite electrode; the air inlet pipe and the water inlet are coaxially arranged, and one end of the air inlet pipe penetrates into the cylinder; at least two iron electrodes; and the sealing plug is arranged in the air outlet. According to the invention, a reverse pole method is adopted, the cathode with reduced electro-Fenton performance caused by scaling is adjusted to be the anode, and the anode oxidizes water to generate H < + > to reduce the pH value, so that the scaling on the surface of the catalyst is removed. When the electro-Fenton reactor is used for waste gas purification, volatile organic compounds (VOCs) in gas can be oxidized without changing a cathode and an anode, so that the function of effectively purifying waste gas is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste treatment, and particularly to an electro-Fenton reactor and a method for treating pollutants using the same. Background Art

[0002] With the rapid development of cities, some wastewaters are extremely difficult to degrade, such as antibiotic-containing wastewater, printing and dyeing wastewater, high-COD wastewater, etc. Usually, advanced oxidation treatment of water is carried out electrochemically. This method is widely used and does not require the generation of additional waste.

[0003] Currently, electrochemical methods are mainly divided into two types. One type of water oxidation can be directly oxidized at the anode or generate free radicals at the anode for oxidation. The anode materials required for this application scenario should have a high oxygen evolution overpotential and corrosion resistance at high potentials. The commonly used BDD electrode can meet the performance requirements but has a high cost; the Ti4O7 electrode mostly remains in the laboratory stage, and there is no large-area electrode on the market. The other type of water oxidation can also generate hydrogen peroxide at the cathode and then generate free radicals through the Fenton reaction for oxidation, that is, the electro-Fenton reaction. The electro-Fenton reaction will increase the pH at the cathode, resulting in scaling, which leads to a decrease in the reaction efficiency. It can be seen that the electrochemical method has the following disadvantages: 1. The efficiency of a single electrode reaction needs to be improved. For example, when the anode oxidizes, the hydrogen evolution reaction may occur at the cathode, and the cathode reaction does not contribute to the oxidation of the wastewater. When the electro-Fenton reaction occurs at the cathode, the oxygen evolution reaction may occur at the anode, and the oxygen evolution reaction does not contribute to the oxidation of the wastewater. 2. The scaling problem of the electro-Fenton cathode. Scaling on the cathode surface can lead to a reduction in the active sites of the catalyst and a decrease in the electrode performance. 3. The problem of high cost of corrosion-resistant anodes.

[0004] In summary, how to solve the scaling problem of the cathode of the electro-Fenton reactor, meet the requirements of low anode cost, high oxygen evolution potential and corrosion resistance, and be able to jointly apply the structure for sewage treatment and waste gas purification has become an urgent technical problem in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide an electro-Fenton reactor, system and control method to solve the defects mentioned in the background art.

[0006] To achieve the above purpose, the present invention provides an electro-Fenton reactor, which comprises:

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

[0008] The composite electrode located above is the cathode, and the composite electrode located below is the anode; the cylinder body can be flipped to alternately use the composite electrodes;

[0009] An intake pipe, coaxially arranged with the water inlet and having one end penetrating into the cylinder body;

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

[0011] A sealing plug, arranged in the air outlet, used to seal each air outlet below the cylinder body.

[0012] Preferably, when the electro-Fenton reactor is used for sewage treatment, the water inlet is used to send sewage into the cylinder body, the intake pipe is used to input air into the cylinder body, and the composite electrodes are alternately used by flipping the cylinder body during the treatment process.

[0013] Preferably, when the electro-Fenton reactor is used for waste gas purification, the water inlet is used to send water with conductivity but no scaling into the cylinder body, and the intake pipe is used to introduce waste gas into the cylinder body.

[0014] Preferably, the composite electrode includes:

[0015] A conductive substrate, a catalytic layer and a hydrophobic layer arranged in sequence; wherein, the catalytic layer is composed of conductive micro-nano particles, a graphene structure and a hydrophobic polymer; the hydrophobic layer partially covers the catalytic layer, the hydrophobic layer is located on the side close to the axis of the cylinder body, and the conductive substrate is located on the side far from the axis of the cylinder body.

[0016] Preferably, the conductive substrate, the catalytic layer and the hydrophobic layer all have ventilation holes to enable gas to float upward through the ventilation holes to the air outlet.

[0017] Preferably, the conductive micro-nano particles 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 graphene mixture; the graphene mixture is composed of graphene and partially oxidized graphene.

[0019] Preferably, a guide ring is fixedly connected to the outside of the cylinder body, at least two first positioning rollers and at least two second positioning rollers are in rolling contact in the guide ring, the first positioning rollers are located below the second positioning rollers, the first positioning rollers and the second positioning rollers are rotationally connected to a bracket through a rotating shaft, the first positioning rollers are electrically connected to the composite electrode located above, the second positioning rollers are electrically connected to the composite electrode located below, and a flipping drive component is installed on the outside of the cylinder body.

[0020] Preferably, the flipping drive component:

[0021] A toothed ring fixedly connected to the outer side of the cylinder body, the toothed ring meshes with a drive gear, the drive gear is axially connected to a drive motor, and the drive motor is installed on the bracket;

[0022] A plurality of conductive blocks are embedded in the guide ring, the conductive blocks are electrically connected to the corresponding composite electrodes through connecting wires, the first positioning roller is in conductive contact with the conductive block located below, the second positioning roller is in conductive contact with the conductive block located below, and the first positioning roller and the second positioning roller are insulated from the guide ring and the bracket.

[0023] A method for treating pollutants by an electro-Fenton reactor, the method uses the electro-Fenton reactor described in the foregoing solution, and the method includes:

[0024] Connect the composite electrode located above to the negative electrode, and connect the composite electrode located below to the positive electrode;

[0025] When performing sewage treatment, after reacting for a certain time, flip the cylinder body, keep the composite electrode located above connected to the negative electrode, and the composite electrode located below connected to the positive electrode, and continue to treat;

[0026] When performing waste gas treatment, the cylinder body does not flip and continues to treat.

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

[0028] The present invention discloses an electro-Fenton reactor, a system and a control method. The reactor includes a cylinder body with water inlets and outlets on both sides, at least two composite electrodes, an air inlet pipe, at least two iron electrodes and a plurality of sealing plugs; a plurality of composite electrodes are arranged on the support net inside the cylinder body; when the electro-Fenton reactor is used for sewage treatment, the composite electrodes in the electro-Fenton reactor simultaneously play the roles of the cathode and the anode, and the electrochemical reaction efficiency of sewage degradation is significantly improved. In addition, the present invention adopts a rotating pole inversion method, and adjusts the cathode whose electro-Fenton performance is reduced due to scaling to the anode by rotating the cylinder body. The anode oxidizes water to generate H + to lower the pH, thereby removing the scale on the surface of the catalyst. When the electro-Fenton reactor is used for waste gas purification, there is no need to change the cathode and anode, and the volatile organic compounds VOCs in the gas can be oxidized, so as to effectively purify the waste gas. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 Structural schematic diagram of the electro-Fenton reactor according to the embodiment of the present invention;

[0031] Figure 2 Structural schematic diagram of the electro-Fenton reactor after removing the cylinder according to the embodiment of the present invention;

[0032] Figure 3 Front view sectional structural schematic diagram according to the embodiment of the present invention;

[0033] Figure 4 Side view sectional structural schematic diagram according to the embodiment of the present invention;

[0034] Figure 5 Structural schematic diagram of the composite electrode according to the embodiment of the present invention;

[0035] Figure 6 Structural schematic diagram of the cooperation between the guide ring and the first positioning roller and the second positioning roller according to the embodiment of the present invention.

[0036] Among them, 1. Cylinder; 101. Tooth ring; 102. Guide ring; 103. Conductive block; 104. Connecting wire; 2. Support net; 201. Anti-disconnection 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. Bracket; 1201. Driving motor; 1202. Driving gear; 1203. First positioning roller; 1204. Second positioning roller; 13. Ventilation hole. Specific embodiments

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0038] The purpose of the present invention is to provide an electro-Fenton reactor, system and control method to solve the defects mentioned in the background technology.

[0039] To make the above 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] As Figure 1-2 shown, the present invention discloses an electro-Fenton reactor, which includes:

[0041] A cylinder body 1 with water inlets 5 and water outlets 6 on both sides; both the upper and lower sides of the cylinder body 1 are provided with gas outlets 8; at least two composite electrodes 3 are arranged inside the cylinder body;

[0042] The composite electrode 3 located above is the cathode 10, and the composite electrode 3 located below is the anode 11; the cylinder body 1 can be flipped to alternately use the composite electrodes 3;

[0043] An air inlet pipe (7), coaxially arranged with the water inlet (5) and one end penetrating into the cylinder body (1);

[0044] At least two iron electrodes 4, located on the side away from the axis of the cylinder body 1 and respectively arranged corresponding to the composite electrodes 3; the iron electrode is also called a 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 arranged in the gas outlet 8 for sealing each gas outlet 8 below the cylinder body 1. The water inlet 5 is used to input wastewater into the cylinder body 1, and the water outlet 6 is used to discharge the degraded wastewater in the cylinder body 1; due to the action of gravity, the gas outlets 8 above the cylinder body 1 are separated from the sealing plug 9, and the gas outlets 8 below the cylinder body 1 are sealed with the sealing plug 9 by gravity and water pressure; two support nets 2 are arranged inside the cylinder body 1, and a plurality of composite electrodes 3 are arranged on the support nets 2 inside the cylinder body 1. The air inlet pipe 7 is used to introduce air or waste gas into the cylinder body 1, and the gas floats up after entering through the air inlet pipe 7. Hydrogen peroxide is generated on the surface of the upper composite electrode 3, and the hydrogen peroxide reacts with the iron electrode 4 to carry out the electro-Fenton reaction, and finally the gas is discharged through the gas outlets 8 above the cylinder body 1.

[0046] When the electro-Fenton reactor is used for waste gas purification, the water inlet 5 is used to send water with conductivity but no scaling into the cylinder body 1, and the air inlet pipe 7 is used to introduce waste gas into the cylinder body 1. Then, the volatile organic compounds VOCs in the waste gas can be oxidized, and the germs therein can be treated, so as to achieve purification. The anode and cathode do not need to be swapped during the whole process. In addition, the application scenarios can include: places such as hospitals, hotels, shopping malls, factories, etc. that need to purify the air. For example, some factories emit odorous tail gases. By introducing the tail gases into this reactor, purification can be achieved.

[0047] When the electro-Fenton reactor is used for sewage treatment, the water inlet 5 is used to send sewage into the cylinder body 1, and the air inlet pipe 7 is used to input air. After working for a certain period of time, the performance of the cathode 10 of the reactor may decline due to scaling. At this time, the cylinder body 1 of the reactor is controlled to rotate, and the cathode and anode are alternately changed, always keeping the composite electrode 3 on the upper side as the cathode 10 and the composite electrode 3 on the lower side as the anode 11 (that is, the original composite electrode 3 as the cathode 10 is changed to the anode 11, and the original composite electrode 3 as the anode 11 is changed to the cathode 10); when the position of the composite electrode 3 is swapped, the iron electrode 4 that was originally on the upper side of the cathode 10 is now on the lower side of the anode 11, and the iron electrode 4 is separated from the anode 11 due to its own gravity, avoiding corrosion on the anode 11; there are gas outlets 8 at the top and bottom of the cylinder body 1 of the reactor, and the gas outlets 8 are provided with sealing plugs 9, and the sealing plugs 9 can be conical. The sealing plug 9 of the top gas outlet 8 sinks under the action of gravity to generate an exhaust passage; the sealing plug 9 of the bottom gas outlet 8 is closed under the action of water pressure; the wastewater outlet remains unchanged when the reactor rotates.

[0048] The composite electrode 3 of the present invention can be fixed on the support net 2 by means such as sewing. Specifically, the hydrophobic layer 33 is in contact with the support net 2, and the conductive substrate 31 is in contact with the iron electrode 4. In the present invention, the composite electrode 3 is fixed on the support net 2 by means such as sewing, and an anti-disengagement frame 201 is fixedly connected to the side of the support net 2 away from the axis of the cylinder body 1, and the iron electrode 4 is movably arranged inside the anti-disengagement frame 201, and the purpose is to keep the electrode position stable during pole inversion.

[0049] Both the cathode 10 and the anode 11 of the electro-Fenton reactor of the present invention adopt the above-mentioned composite electrode 3. One side of the composite electrode 3 has hydrophobicity, and the other side has conductivity; the above-mentioned composite electrode 3 needs to be punched to form an upper and lower communication structure, and the ventilation holes are beneficial for the floating gas to pass through, and at the same time promote 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 set as at least one of graphite paper or carbon fiber cloth. When using graphite paper as the conductive substrate 31, if the strength is not enough, it can be reinforced by setting a rigid support structure, for example, a mesh structure, etc.

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

[0052] A conductive substrate 31, a catalytic layer 32, and a hydrophobic layer 33 arranged in sequence; wherein, the catalytic layer 32 is composed of conductive micro-nano particles, a graphene structure, and a hydrophobic polymer; the hydrophobic layer 33 partially covers the catalytic layer 32, the hydrophobic layer 33 is located on the side close to the axis of the cylinder body 1, and the conductive substrate 31 is located on the side far from the axis of the cylinder body 1.

[0053] For a further optimized solution, the conductive substrate 31, the catalytic layer 32, and the hydrophobic layer 33 all have ventilation holes 13, so that gas can float upward through the ventilation holes 13 to the air outlet 8.

[0054] For a further optimized solution, the conductive micro-nano particles include at least one of Ti4O7, boron-doped diamond, titanium carbide, titanium nitride, and boron-doped silicon carbide, which are micro-nano particles with corrosion resistance and conductivity. The graphene structure is graphene or a graphene mixture; the graphene mixture is composed of graphene and partially oxidized graphene. The hydrophobic polymer is made of PTFE emulsion. The hydrophobic layer 33 is formed by screen-printing PTFE emulsion on the surface of the catalytic layer 32 and then performing heat treatment, and has hydrophobicity.

[0055] The iron electrode 4 of the present invention, also known as the Fenton catalytic electrode, can be a wire mesh, iron foam, or a porous material loaded with an iron-containing component, and the corresponding structure of the iron electrode 4 can be selected according to actual needs.

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

[0057] A guide ring 102 is fixedly connected to the outside of the cylinder body 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 through a rotating shaft. The first positioning rollers 1203 are electrically connected to the composite electrode 3 located above, and the second positioning rollers 1204 are electrically connected to the composite electrode 3 located below. A flipping drive component is installed on the outside of the cylinder body 1.

[0058] For a further optimized solution, the flipping drive component:

[0059] A toothed ring 101 fixedly connected to the outside of the cylinder body 1 is meshed with a driving gear 1202. The driving gear 1202 is axially connected to a driving motor 1201, and the driving motor 1201 is installed on the bracket 12;

[0060] A plurality of conductive blocks 103 are embedded in the guide ring 102. The conductive blocks 103 are electrically connected to the corresponding composite electrode 3 through connecting wires 104. The first positioning rollers 1203 are in conductive contact with the conductive blocks 103 located below, and the second positioning rollers 1204 are in conductive contact with the conductive blocks 103 located below. The first positioning rollers 1203 and the second positioning rollers 1204 are insulated from the guide ring 102 and the bracket 12.

[0061] With such a setting, when the cylinder body 1 is flipped, the driving motor 1201 is controlled to rotate. By the meshing action between the driving gear 1202 and the tooth ring 101, the cylinder body 1 can be flipped by 180 degrees. The cooperation between the guiding ring 102 and the first positioning roller 1203 and the second positioning roller 1204 can ensure the normal rotation of the cylinder body 1. Connect the rotating shafts of the first positioning roller 1203 and the second positioning roller 1204 to the corresponding positive and negative electrodes. The rotating shafts are set to be fixed, and the rotating shafts are in contact and rotatably connected with the first positioning roller 1203 and the second positioning roller 1204. The rotating shafts are installed on the bracket 12 and are insulated from the bracket 12. In this way, when the cylinder body 1 rotates, the composite electrode 3 can be powered off. After the cylinder body 1 is flipped in place, the corresponding conductive block 103 also rotates to the corresponding position, ensuring that the composite electrode 3 above the inside of the cylinder body 1 is always the cathode 10 after the cylinder body 1 is flipped.

[0062] The part of the air inlet pipe 7 of the present invention located inside the cylinder body 1 is communicated with an aeration plate 701. The aeration plate 701 is of a hollow structure, and a plurality of aeration holes are opened on the upper and lower end faces of the aeration plate 701.

[0063] The air inlet pipe 7 and the water inlet 5 in the present invention are coaxially arranged. The air inlet pipe 7 and the water inlet 5 can be fixedly installed on the bracket 12 or fixedly installed on the ground through a mounting rod. One end of the water inlet 5 far from the air inlet pipe 7 is closed with the air inlet pipe 7. A pipe body (not shown in the figure) is communicated on the side wall of the water inlet, which can realize the functions of air intake and liquid intake without affecting the flipping of the cylinder body 1. When the cylinder body 1 rotates, it does not affect the introduction of gas into the air inlet pipe 7. The present invention preferably connects the water inlet 5 and the cylinder body 1 through a sealing bearing, that is, when the reactor cylinder body 1 rotates, the water inlet 5 remains in place; the above is only one embodiment, and other connection methods can also be adopted.

[0064] Different from traditional reactors with vertical electrodes, the cathode 10 and the anode 11 of the reactor disclosed in the present invention are horizontally placed and are respectively located in the upper and lower parts of the reactor. There is an air inlet pipe 7 between the two composite electrodes 3. The air bubbles introduced by the air inlet pipe 7 float to the cathode 10 area, and hydrogen peroxide is generated through an electroreduction reaction at the cathode 10. The hydrogen peroxide reacts with the iron electrode 4 adjacent to the composite electrode 3 to generate Fenton's reagent. The present invention places the electrodes horizontally, which not only helps the floating bubbles to pass through the ventilation holes 13 of the cathode 10, thereby improving the oxygen utilization rate, but also ensures that the iron electrode 4 is in electrical contact with the cathode 10 and is electrically separated from the anode 11 under the action of gravity and water pressure.

[0065] Taking Ti4O7 as the conductive micro-nano particles, graphene as the graphene structure, and PTFE emulsion as the hydrophobic polymer as an example for discussion, the preparation method is as follows: Ball-mill Ti4O7 powder with graphene and PTFE emulsion, and coat it on graphite paper. PTFE plays a bonding role and provides local hydrophobicity at the same time. Graphene oxide adheres to the surface of Ti4O7 during the ball-milling process and can be partially converted into graphite. The slurry is coated on graphite paper and hot-pressed (carbon nanotubes or other catalytic components can also be added to the slurry), which provides bonding strength and a good electron channel for Ti4O7. Coating PTFE emulsion on the surface of the catalytic layer 32 by screen printing and further heat-treating to generate hydrophobicity. Punch holes in the composite layer to form an upper and lower ventilation hole structure, which is the composite electrode 3. One side of the composite electrode 3 is hydrophobic but non-conductive, and the other side is conductive but not hydrophobic-treated. It has conductivity to enable the iron electrode 4 to contact the composite electrode 3 and be used as the dual cathode 10. It has hydrophobicity to ensure oxygen adsorption and further reduction. The conductive side may be gradually corroded when used as the anode 11. The present invention can also coat the catalytic layer 32 on both sides of the conductive substrate 31, coat the slurry of PTFE and conductive carbon materials on the surface of the catalytic layer, and then hot-press to make both sides have a certain degree of hydrophobicity and conductivity at the same time. Coating the catalytic layer 32 on both sides increases the corrosion resistance compared with coating on one side.

[0066] During use, the anode 11 undergoes an oxidation reaction, which can generate free radicals or directly oxidize refractory organic substances on the electrode. There is an air inlet pipe 7 below the cathode 10. The gas floats up, passes through the hydrophobic surface, and generates hydrogen peroxide under the catalytic action of graphene in the catalytic layer 32. The hydrogen peroxide contacts the iron electrode 4 and undergoes an electro-Fenton reaction. The iron electrode 4 is oxidized to generate free radicals. The iron electrode 4 contacts the graphite paper, and the surface-oxidized iron electrode 4 can be reduced. Since the reduction process on the cathode 10 will cause the pH to increase and lead to a scaling reaction, reducing the electrode performance, the cathode 10 can be converted into the anode 11 by inverting the poles. Both Ti4O7 and graphene contained in the anode 11 have corrosion resistance. In the acidic environment generated by the anode 11, the scale can be dissolved, and the electrode can be reused for the electro-Fenton reaction on the cathode 10.

[0067] Since the iron electrode 4 used on the anode 11 can be oxidized, the iron electrode 4 on the anode 11 needs to be separated from the anode 11 (at this time, the iron electrode 4 is no longer energized after being separated from the anode 11), which can be achieved by gravity.

[0068] To solve the scaling problem of the cathode 10, the present invention adopts the method of inverting the poles, adjusting the cathode 10 with reduced electro-Fenton performance due to scaling to the anode 11. The anode 11 oxidizes water to generate H+ and reduces the pH near the electrode, thereby removing the scale on the surface of the catalyst.

[0069] To solve the problem of high cost of corrosion-resistant electrodes, the present invention uses inexpensive conductive materials such as graphite paper and carbon fiber cloth as the substrate, grinds Ti4O7, graphene and PTFE emulsion and then coats them on the substrate, and then hot-presses. In this electrode, Ti4O7 can increase the oxygen evolution overpotential and corrosion resistance of the electrode, graphene can catalyze the oxygen reduction and also has corrosion resistance, and PTFE provides hydrophobicity for oxygen adsorption. This electrode has a low cost and can be used for both the cathode 10 and the anode 11 at the same time, providing support for the scale removal by electrode reversal.

[0070] Compared with the reactions occurring on a single electrode, this electro-Fenton reactor simultaneously plays the roles of the cathode 10 and the anode 11. The anode should have a certain oxidation resistance and a relatively high oxygen evolution potential, and can generate free radicals at a high voltage; the cathode can generate hydrogen peroxide and further generate Fenton's reagent. The cathode and the anode work simultaneously, and the electrochemical reaction efficiency of sewage degradation is significantly improved.

[0071] Furthermore, the present invention also discloses an electro-Fenton reaction control system for sewage treatment. The system includes: the above-mentioned electro-Fenton reactor, a power supply, an output polarity conversion circuit and a controller; the output polarity conversion circuit is respectively connected to the power supply and the composite electrode 3, and the controller is connected to the output polarity conversion circuit; the electro-Fenton reactor for sewage treatment is used to degrade sewage; the power supply is used to provide electric 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, realizing the reversal of the cathode and the anode. The output polarity conversion circuit in this embodiment is a full-bridge inverter circuit composed of four switching tubes, capacitors, inductors, etc. and various improved circuits. By only controlling the on-time and off-time of the switches, the output voltage polarity conversion of the output polarity conversion circuit can be realized, and the specific structure of this part will not be elaborated in detail.

[0072] The system of the present invention further includes: an induction sensor, connected to the controller, for sensing the rotation position of the cylinder body 1 and sending it to the controller, so that the controller determines whether the set position is reached. If the set position is reached, the output polarity conversion circuit is further controlled to change the polarity of each composite electrode 3. The induction sensor mentioned in this embodiment may be an infrared emitter and an infrared receiver. The infrared receiver is arranged at a certain position of the cylinder body 1, and the infrared emitter is arranged at a certain fixed position. When the cylinder body 1 rotates to the position corresponding to the infrared emitter, the infrared receiver sends the infrared signal received to the controller, so that the controller controls the opening and closing of the switch according to the received signal, and further realizes the anode-cathode conversion of the composite electrode 3. Or the infrared emitter is arranged at a certain position of the cylinder body 1, and the infrared receiver is arranged at a certain fixed position. When the cylinder body 1 rotates to the position corresponding to the infrared receiver, the infrared receiver sends the infrared signal received to the controller, so that the controller controls the opening and closing of the switch according to the received signal, and further realizes the anode-cathode conversion of the composite electrode 3. The induction sensor may also be set as a distance measuring sensor. The distance measuring sensor is arranged on the cylinder body 1 and is located between two air outlets 8. When the controller determines that the distance between the distance measuring sensor and the ground is the smallest, it means that the cylinder body 1 has rotated half. At this time, the switch is controlled to conduct and turn off, and further the anode-cathode conversion of the composite electrode 3 is realized. The above is only an example and does not limit the present application.

[0073] Further, the present invention also discloses an electro-Fenton reaction control method for sewage treatment. The method is used to control the above system, and the method includes:

[0074] Turn on the power supply, close the first switch and the second switch of the output polarity conversion circuit, and open the third switch and the fourth switch, so that the upper composite electrode 3 is the cathode 10 and the lower composite electrode 3 is the anode 11, and then control the cylinder body 1 to introduce wastewater.

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

[0076] Experimental comparison:

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

[0078] 2. Cathode performance: A composite electrode with an area of 12 cm 2 was used as the cathode, a Pt sheet electrode was used as the anode, and a 500 mL 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 and Ca 2+ at a concentration of 100 mg / L). The pH was adjusted to 3, air was bubbled into the solution, the current density was 14 mA / cm 2 . After 20 minutes of electrolysis, the COD removal rate was 62%.

[0079] 3. Using the reactor of the present invention: A composite electrode with an area of 12 cm2 was used as both the cathode and the anode, and a 500 mL rhodamine B (RhB) solution with an initial concentration of 200 mg / L was used as the simulated wastewater, (Ca 2+ at a concentration of 100 mg / L, without Fe 2+ ), the pH was neutral, the current density was 14 mA / cm 2 . After 20 minutes of electrolysis, the COD removal rate was 90%.

[0080] 4. Electrode stability: Under the conditions of 2, the cathode performance decreased after 5 cycles. Using the reactor of the present invention and the pole-reversing method, the reaction continued for 240 hours, the poles were reversed 10 times, and the electrochemical performance remained basically unchanged.

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

[0082] 6. Treatment of toluene-containing waste gas: A simulated waste gas with a toluene content of 400 mg / m 3 was prepared in a 1 m 3 container. The waste gas was introduced into the inlet of the reactor of the present invention through an air pump at a rate of 2 L / min, and the outlet gas was introduced into the container to achieve a closed-loop cycle. The volume of the reactor was 600 mL, containing 500 mL of solution, and the pH of the solution was 3. After 10 hours of treatment, the toluene content in the waste gas was detected by gas chromatography to be 10 mg / m 3 , indicating that the toluene removal rate reached 97.5%.

[0083] From the above experiments, it can be seen that using the reactor disclosed in the present invention can not only keep the electrochemical performance of the reactor basically unchanged, but also improve the COD removal rate compared with a single electrode. This reactor can be used for both wastewater treatment and waste gas treatment.

[0084] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method section.

[0085] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method of the present invention and its core idea. At the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

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

2. The electro-Fenton reactor according to claim 1, characterized in that: When the electro-Fenton reactor is used to treat sewage, the water inlet (5) is used to feed sewage into the cylinder (1), and the air inlet pipe (7) is used to input air into the cylinder (1). During the treatment process, the cylinder (1) is turned over to alternately use the composite electrodes (3).

3. The electro-Fenton reactor according to claim 1, characterized in that: When the electro-Fenton reactor is used to purify waste gas, the water inlet (5) is used to introduce conductive but non-scaling water into the cylinder (1), and the air inlet pipe (7) is used to introduce waste gas into the cylinder (1).

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

5. The electro-Fenton reactor according to claim 4, characterized in that: The conductive substrate (31), the catalytic layer (32) and the hydrophobic layer (33) all have vents (13) so that the gas can float upward to the gas outlet (8) through the vents (13).

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

7. The electro-Fenton reactor according to claim 4, characterized in that: The graphene structure is graphene or a graphene mixture; the graphene mixture consists of graphene and part of oxidized graphene.

8. The electro-Fenton reactor according to claim 1, characterized in that: The outer side of the cylinder (1) is fixedly connected to a guide ring (102), and at least two first positioning rollers (1203) and at least two second positioning rollers (1204) are in rolling contact with the guide ring (102), the first positioning roller (1203) is located below the second positioning roller (1204), the first positioning roller (1203) and the second positioning roller (1204) are rotatably connected to the bracket (12) via a rotating shaft, the first positioning roller (1203) is electrically connected to the composite electrode (3) located above, and the second positioning roller (1204) is electrically connected to the composite electrode (3) located below, and a turning drive component is installed on the outer side of the cylinder (1).

9. The electro-Fenton reactor according to claim 8, characterized in that The flip driving component: A gear ring (101) fixedly connected to the outside of the cylinder (1), the gear ring (101) being meshed with a driving gear (1202), the driving gear (1202) being axially connected to a driving motor (1201), and the driving motor (1201) being mounted on the bracket (12); The guide ring (102) is embedded with a plurality of conductive blocks (103), the conductive blocks (103) being electrically connected to the corresponding composite electrodes (3) via connecting wires (104), the first positioning roller (1203) being in conductive contact with the conductive blocks (103) located below, the second positioning roller (1204) being in conductive contact with the conductive blocks (103) located below, and the first positioning roller (1203) and the second positioning roller (1204) being insulated from the guide ring (102) and the bracket (12).

10. 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 to 9, and the method comprises: Connecting the composite electrode (3) located at the top to the negative electrode, and connecting the composite electrode (3) located at the bottom to the positive electrode; When sewage treatment is being carried out, the cylinder (1) is turned over after a certain reaction time, the composite electrode (3) located at the top is kept connected to the negative electrode, and the composite electrode (3) located at the bottom is kept connected to the positive electrode, and treatment is continued; When the waste gas is being treated, the cylinder (1) continues the treatment without being turned over.

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