Gas-liquid mixed electrochemical oxidation device

Abstract

The application relates to a gas-liquid mixed electrochemical oxidation device which comprises a reaction device and a support, the reaction device is divided into a gas buffer chamber, an electrochemical reaction chamber and a gas-water separation chamber, a water inlet is arranged on the side wall of the reaction device, a gas inlet is arranged at the bottom of the gas buffer chamber, the gas-water separation chamber is provided with a gas outlet and a water outlet, the gas buffer chamber is connected with the electrochemical reaction chamber through a first-stage flange, a cathode is arranged between the two flanges of the first-stage flange, the cathode comprises a cathode conductive plate and a tubular cathode group, the cathode is located below the water inlet, the electrochemical reaction chamber is connected with the gas-water separation chamber through a second-stage flange, an anode is arranged between the two flanges of the second-stage flange, and the electrochemical reaction chamber is filled with carbon-based fillers. The composite reaction system composed of the tubular cathode, the anode and the carbon-based fillers can realize various physical and chemical synergistic reactions such as electrochemical oxidation, catalytic oxidation and adsorption, and can efficiently degrade organic matter COD and ammonia nitrogen in high-salinity wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a gas-liquid mixed electrochemical oxidation device. BACKGROUND

[0002] The electrochemical oxidation technology can degrade organic matter, ammonia nitrogen and the like in water through direct oxidation and indirect oxidation (generating •OH and the like oxidizing substances) of anode, and is very suitable for oxidation treatment of high-salt organic wastewater. However, the single electrochemical oxidation treatment has high energy consumption and large equipment investment. The existing technology combines the electrochemical oxidation technology with the ozone oxidation technology, but the combination technology is basically the result of direct addition of the two, that is, “1+1=2”. The combination technology not only has large occupation area and high energy consumption, but also has the problems of low ozone utilization rate, high residual ozone concentration of tail gas, incomplete tail gas treatment, secondary pollution risk and the like, and low current efficiency and electrode corrosion, and the overall treatment efficiency is not significantly improved, and the investment is not obviously reduced, thereby limiting the large-scale application of the combination technology.

[0003] Therefore, it is urgent to develop an efficient (“1+1>2”) electrochemical oxidation technology to solve the technical problems of low treatment efficiency, high energy consumption and high investment cost of high-salt wastewater treatment. SUMMARY

[0004] The present application aims to provide a gas-liquid mixed electrochemical oxidation device, which can solve the technical problems mentioned in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a gas-liquid mixed electrochemical oxidation device, comprising a reaction device and a support, the reaction device is fixedly connected to the upper side of the support, the reaction device is sequentially divided into a gas buffer chamber, an electrochemical reaction chamber and a gas-water separation chamber from bottom to top, the gas buffer chamber is separated from the electrochemical reaction chamber by a cathode, and the electrochemical reaction chamber is separated from the gas-water separation chamber by an anode; a water inlet is arranged at the lower end of the side wall of the electrochemical reaction chamber, an air inlet is arranged at the bottom of the gas buffer chamber, an air outlet is arranged at the top of the gas-water separation chamber, and a water outlet is arranged at the side wall of the gas-water separation chamber; the gas buffer chamber and the electrochemical reaction chamber are connected through a first-stage flange, and a cathode is arranged between the upper and lower flanges of the first-stage flange; the cathode comprises a cathode conductive plate and a tubular cathode group, and a cathode terminal is protruded on one side of the cathode conductive plate; the cathode is located below the water inlet; the electrochemical reaction chamber and the gas-water separation chamber are connected through a second-stage flange, and an anode is arranged between the upper and lower flanges of the second-stage flange; the electrochemical reaction chamber is filled with carbon-based fillers, the carbon-based fillers are located below the anode, and above the water inlet.

[0006] In a preferred embodiment, the reaction device is a cylindrical structure with a height-diameter ratio of (1-4):1. The reactor with this height-diameter ratio has good mechanical stability, is not prone to tipping, and has low investment cost.

[0007] In a preferred embodiment, the tubular cathode group is arranged by multiple cathode tubes, the cathode tube is a hollow cylindrical structure, the axial center distance between two adjacent cathode tubes is 12-20 mm, the height of the cathode tube is 15-20 mm, the outer diameter is 8-10 mm, the wall thickness is 1-2 mm, and the cathode tube is cast and fixed on the cathode conductive plate. Compared with the traditional flat electrode, the present application adopts each hollow cathode tube arranged in a spaced manner, which can effectively increase the gas-liquid contact area, prolong the gas diffusion path, obtain longer gas residence time, make the reaction more sufficient, and obtain better oxidation effect. The gas can uniformly penetrate out of the pores, and the aeration effect is better.

[0008] In a preferred embodiment, a fixed water-permeable and air-permeable support plate is arranged above the water inlet in the electrochemical reaction chamber, and a detachable mesh conductive separation layer is arranged below the anode. The distance between the mesh conductive separation layer and the anode is 8-12 mm, the mesh conductive separation layer is connected with the electrochemical reaction chamber through buckles, and the carbon-based filler is filled between the support plate and the conductive separation layer. The support plate ensures that the carbon-based filler does not contact the cathode, and the mesh conductive separation layer ensures that the carbon-based filler is not driven into contact with the anode by the gas flow and water flow, and the upper end is detachable to facilitate cleaning and replacement of the carbon-based filler.

[0009] In a preferred embodiment, the filling height of the carbon-based filler is 1:(3-5) of the height of the reaction device. The carbon-based filler with this ratio can ensure sufficient reaction surface area and catalytic active sites, and ensure good gas-liquid mass transfer efficiency.

[0010] In a preferred embodiment, the carbon-based filler is sulfur / fluorine co-doped carbon particles with a particle size of 2-6 mm. In this scheme, the carbon-based filler can obtain more electrocatalytic active sites after doping with sulfur / fluorine elements, and its large specific surface area and strong adsorption capacity are also very beneficial to the removal of organic matter and ammonia nitrogen in water.

[0011] In a preferred embodiment, the upper and lower flanges of the first and second flanges are respectively fixedly connected by bolts and nuts, and sealing gaskets are arranged between the two flanges that are vertically opposite to each other. The flange connection method adopted in this scheme is flexible and convenient to disassemble and assemble, and is convenient for maintenance. The sealing gaskets can ensure the sealing of the junction between the two adjacent chambers.

[0012] In a preferred embodiment, the cathode tube upper end face has a top, the upper end face is 8-15 mm higher than the cathode conductive plate; the lower end face of the cathode tube has no bottom, the lower end face is flush with the lower bottom surface of the cathode conductive plate, and is communicated with the gas buffer chamber, so that the gas in the gas buffer chamber can only enter the electrochemical reaction chamber through each cathode tube.

[0013] In a preferred embodiment, a separation layer plate is arranged in the gas-water separation chamber, the separation layer plate is horizontally arranged below the water outlet, and the separation layer plate is made of a water-permeable and gas-permeable material. This scheme can slow down the rising speed of the water flow, make the water flow overflow stably, and make the tail gas flow rise smoothly, thereby achieving the function of gas-water separation.

[0014] In a preferred embodiment, the tube wall of the cathode tube comprises a gas diffusion layer, a catalytic layer and a current collector layer arranged from inside to outside. The gas diffusion layer has good gas permeability and hydrophobicity, so that the gas can enter the electrochemical reaction chamber in one direction; the catalytic layer can catalyze the reduction of oxygen to hydrogen peroxide; and the current collector layer is a support frame and main conductive material of the entire cathode tube, and has a porous structure, so that the gas can uniformly penetrate out of the pores, and also has a good aeration effect.

[0015] Compared with the prior art, the beneficial effects of the present application are:

[0016] 1) The gas-liquid mixed electrochemical oxidation device provided by the present application is provided with vertical array type hollow tube cathodes, compared with ordinary horizontally arranged flat plate cathodes, the gas-liquid contact area is large, the gas path is long, the mass transfer efficiency is high, the upward diffusion of the gas is facilitated to form bubbles, and the uniform mixing with the wastewater is accelerated; and the deposition of suspended particle pollutants in the water on the outer surface of the cathode is reduced, and the risk of cathode pollution is reduced. In addition, the gas inlet direction and the water inlet mode of the device are designed to be perpendicular, the rising gas can play a flushing effect on the horizontally arranged water inlet, which can not only ensure the uniform mixing and flow of the wastewater in the reaction system, reduce the concentration difference of the wastewater along the horizontal direction, but also reduce the deposition of pollutants on the surface of the cathode during high current density operation, thereby reducing the frequency of cathode pollution.

[0017] In the powered state, the device can be supplied with air or ozone gas, the set hollow tube cathode has the dual functions of an aerator and an electrode, on the one hand, it can act as an aerator to make the gas efficiently permeate and prevent water molecules from permeating, so that the gas can be quickly and uniformly mixed with the water molecules on the outer surface of the cathode after passing through the cathode, and the aeration is uniform without dead angles compared with ordinary aerators; on the other hand, as a cathode, it can efficiently capture oxygen and produce hydrogen peroxide on the outer surface of the cathode, thereby providing reaction raw materials for the subsequent generation of free radicals to oxidize organic matter, and improving the overall electrochemical oxidation efficiency of the device.

[0018] 3) The device is provided with carbon-based filler in the electrochemical reaction chamber, which is activated carbon-based material doped with sulfur / fluorine elements. Due to the difference in electronegativity between the doped sulfur S / fluorine F atoms and the carbon atoms C, the charge distribution of the activated carbon-based material changes. On the one hand, it can improve the capture / adsorption of pollutants and oxygen in water by carbon-based filler, and improve the adsorption performance. On the other hand, the doped sulfur S / fluorine F atoms occupy part of the space position of carbon atoms, so that the active site of the activated carbon-based material increases. The active site can catalyze and accelerate the electrochemical reaction between the anode and the cathode and the catalytic oxidation reaction of hydrogen peroxide, thereby improving the oxidation reaction efficiency of the device. In addition, sulfur S / fluorine F is a non-metallic element, which is combined with carbon C non-metallic element through C-S bond and C-F bond, and the stability of the material is good. The conventional noble metal doped catalyst has poor stability because the metal heteroatoms are easy to participate in chemical reaction and fall off from the carrier during long-term use or operation in acidic conditions. Finally, the carbon-based material itself has good electrical conductivity as the activated carbon, which can be used as a carbon electrode to cooperate with the cathode and anode electrochemical reaction, further improve the oxidation efficiency, so that the whole device has high treatment efficiency, low energy consumption, and greatly reduced investment and processing cost.

[0019] 4) The device is provided with three reaction chambers from bottom to top. The gas enters the gas buffer chamber from the bottom to fill the entire chamber quickly, and then mixes, reacts, separates and discharges with the wastewater during the rising process. The gas and water flow smoothly and uniformly during the whole process, and the reaction efficiency is high. In addition, the three reaction chambers are connected by flanges, which are easy to disassemble. When the carbon-based filler needs to be cleaned or replaced after long-term operation, only part of the flange needs to be disassembled. When cleaning, the entire electrochemical reaction chamber can be taken out to avoid short circuit caused by filler pollution of the anode and cathode, and reduce the cleaning difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the overall structure schematic diagram of the gas-liquid mixed electrochemical oxidation device in the embodiment of the application.

[0021] Figure 2 It is the side view of the gas-liquid mixed electrochemical oxidation device in the embodiment of the application.

[0022] Figure 3 It is Figure 2 It is the sectional view in A-A direction.

[0023] Figure 4 It is the structure schematic diagram of the cathode end in the embodiment of the application.

[0024] Figure 5 It is the right view of the cathode end in the embodiment of the application.

[0025] Figure 6The figure is a structural schematic diagram of a tubular cathode in the embodiment of the present application.

[0026] The meanings of the respective reference numerals in the figure are as follows:

[0027] 1, reaction device; 101, gas buffer chamber; 102, electrochemical reaction chamber; 103, gas-water separation chamber; 104, first-stage flange; 105, second-stage flange; 106, carbon-based filler; 107, cathode tube; 108, gas diffusion layer; 109, catalytic layer; 110, current collector layer; 2, support; 3, water inlet; 4, gas inlet; 5, gas outlet; 6, water outlet; 7, cathode conductive plate; 8, tubular cathode group; 9, sealing gasket; 10, cathode terminal; 11, anode; 12, bolt and nut; 13, separation layer plate; 14, support plate; 15, conductive barrier. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0029] In the description of the present application, it should be understood that the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0030] Referring to Figures 1-3 The present application discloses a gas-liquid mixed electrochemical oxidation device, which comprises a support 2 and a reaction device 1 fixedly connected to the support 2. The reaction device 1 is sequentially divided into a gas buffer chamber 101, an electrochemical reaction chamber 102 and a gas-water separation chamber 103 from bottom to top. The side wall of the reaction device 1 is provided with a water inlet 3 for feeding wastewater to be treated. The bottom of the gas buffer chamber 101 is provided with a gas inlet 4 for feeding air or ozone (mixed gas containing ozone and oxygen). The gas and the liquid are reacted in the electrochemical reaction chamber 102, so that the organic matter and ammonia nitrogen in the wastewater are degraded. The reacted effluent and tail gas are discharged through the water outlet 6 and the gas outlet 5 of the gas-water separation chamber 103, respectively.

[0031] The bracket 2 is a support carrier of the electrochemical oxidation device as a whole, which is configured as a "mouth" shaped structure or a trapezoidal structure, in a hollow tetrahedron shape. By providing the bracket 2, the operation of the reaction device 1 can be more convenient, especially the valves, flanges, instruments and the like provided at the bottom gas inlet 4 position are more convenient for maintenance and repair. When the bracket 2 is a "mouth" shaped structure, the upper and lower two surfaces are parallel and symmetrical, and the left and right two surfaces are parallel and symmetrical; when the bracket 2 is a trapezoidal structure, the area of the upper base is smaller than that of the lower base, and the left and right two surfaces are distributed in an "eight" shape.

[0032] The reaction device 1 as a whole is a cylindrical structure, and the height-diameter ratio is (1-4):1. The mechanical structure of the reactor with the height-diameter ratio is stable, and the investment cost is low.

[0033] The following will be combined again Figures 1-3 The structure of the reaction device 1 will be introduced in detail.

[0034] Specifically, the bracket 2 is fixedly connected with a gas buffer chamber 101 at the top end surface, and the gas inlet 4 is arranged at the bottom of the gas buffer chamber 101. Correspondingly, the top plate of the bracket 2 is provided with a gas inlet channel communicated with the gas inlet 4. The ozone (containing oxygen, wherein the volume concentration of ozone is about 10-20%, and the volume concentration of oxygen is about 80-90%) generated by the ozone generator is introduced from the gas inlet 4, or air is introduced by the air blower. After the gas enters the gas buffer chamber 101, the pressure is released, the gas flow rate is slowed down, the bottom space of the entire reaction device 1 is uniformly filled, and the gas uniformly rises through the cathode, which is beneficial to subsequent more sufficient electrolysis reaction, avoids the problems of uneven and insufficient reaction caused by a high-pressure gas flow rising rapidly, and low gas utilization rate.

[0035] The gas buffer chamber 101 is fixedly connected with an electrochemical reaction chamber 102 above, the electrochemical reaction chamber 102 is filled with carbon-based filler 106, and the bottom end and the top end of the electrochemical reaction chamber 102 are respectively connected with the cathode and the anode 11, that is, the cathode and the anode 11 are respectively covered on the two ends of the electrochemical reaction chamber 102, and participate in the electrolysis reaction together with the carbon-based filler 106 in the middle.

[0036] More specifically, the gas buffer chamber 101 and the electrochemical reaction chamber 102 are connected through the first-stage flange 104, the cathode is connected between the upper and lower two flanges of the first-stage flange 104, and further, combined with Figures 3-5 In the present application, the cathode includes a cathode conductive plate 7 and a tubular cathode group 8, the tubular cathode group 8 is connected to the center of the cathode conductive plate 7, and the side end of the cathode conductive plate 7 protrudes to the far end as a cathode terminal post 10. The gas is transmitted from the gas buffer chamber 101 to the tubular cathode group 8 through the cathode tube 107.

[0037] When connected, the cathode conductive plate 7 is placed between the upper and lower flanges of the first stage flange 104, and the upper and lower flanges of the first stage flange 104 are connected and fixed by the bolt and nut 12, so that the gas buffer chamber 101 and the electrochemical reaction chamber 102 are connected, and the cathode is also fixed. A sealing gasket 9 is provided between the two flanges to ensure the sealing of the cavity. This flange connection method is flexible and easy to disassemble and maintain.

[0038] In actual application, wastewater enters the reaction device 1 through the water inlet 3 and fully contacts the outer surface of the cathode. The gas in the gas buffer chamber 101 enters the electrochemical reaction chamber 102 through the tubular cathode group 8. The gas is uniformly mixed with the wastewater on the outer surface of the cathode during the process of passing through the cathode. The oxygen in the gas reacts at the cathode end to generate hydrogen peroxide, and the reaction principle is as follows:

[0039] O 2 +2H + +2e - →H 2 O 2

[0040] When the gas is ozone, hydrogen peroxide can react with ozone to produce hydroxyl radicals, which can further degrade organic matter in wastewater to generate carbon dioxide and water, and the reaction principle is as follows:

[0041] 2H 2 O 2 +2O 3 →H 2 O + 3O 2 + OH + HO 2

[0042] OH + organic → CO 2 +H 2 O

[0043] The residual ozone gas can further react under the action of the filler catalyst to produce hydroxyl radicals, which can further degrade organic matter in water to generate carbon dioxide and water:

[0044] Filler catalyst

[0045] O 3 +H 2 O ————> 2 OH + O2

[0046] OH + organic → CO 2 +H 2 O

[0047] Hydrogen peroxide can also be catalytically reacted to produce hydroxyl radicals under the catalysis of carbon-based fillers, and then degrade organic matter in water to generate carbon dioxide and water, and the principle is as follows:

[0048] Filler catalyst

[0049] H 2 O 2 ———> OH + OH -

[0050] OH + organic → CO 2 +H 2 O

[0051] In the application, the cathode conductive plate 7 is configured as a round plate structure, adopts copper material, and the tubular cathode group 8 is fixedly connected to the center of the cathode conductive plate 7. The tubular cathode group 8 comprises a plurality of groups of cylindrical cathode tubes 107 arranged in an array, and each cathode tube 107 is closely and uniformly arranged. For example, the cathode tube 107 is a hollow cylindrical structure, the height of a single cathode tube 107 is 15-20 mm, the outer diameter is about 8-10 mm, the wall thickness is about 1-2 mm, the upper end surface of the cathode tube 107 is capped, and the upper end surface is 8-15 mm higher than the cathode conductive plate 7. The bottom of the cathode tube 107 (the end facing the gas buffer chamber 101) is open, that is, the lower end surface of the cathode tube 107 is not capped, and the lower end surface is flush with the lower bottom surface of the cathode conductive plate 7, so that the gas in the gas buffer chamber 101 can only enter the electrochemical reaction chamber 102 through each cathode tube 107. In combination with Figure 6The sidewall and top cover of the cathode tube 107 have the same structure, including a gas diffusion layer 108, a catalyst layer 109, and a current collector layer 110 arranged from the inside out. The gas diffusion layer 108 is about 0.05-0.1 mm thick and is made of PTFE and carbon paper. It has good air permeability and hydrophobicity, allowing gas to enter the electrochemical reaction chamber 102 in one direction. The catalyst layer 109 is 0.03-0.08 mm thick and mainly consists of carbon black. It can catalyze the reduction of oxygen in the gas buffer chamber 101 to hydrogen peroxide. The current collector layer 110 is a porous titanium sheet with a thickness of about 0.92-1.82 mm. It is the supporting frame and main conductive material of the entire cathode tube. Its porous structure allows gas to permeate evenly from the pores and also provides a good aeration effect. Therefore, the hollow cathode tube 107 in this invention can serve as an aerator to allow gas to pass through efficiently while preventing water molecules from passing through, so that the gas can quickly and evenly mix with water molecules on the outer surface of the cathode after passing through the cathode, resulting in uniform aeration without dead zones. On the other hand, as a cathode, a reduction reaction occurs on the outer surface of the cathode tube 107 to produce hydrogen peroxide, which provides reaction raw materials for the subsequent generation of free radicals and the oxidation of organic matter, thereby improving the overall oxidation efficiency of the device.

[0052] For example, the fabrication process of a single cathode tube 107 is as follows:

[0053] 1) The titanium plate is immersed in hydrochloric acid and sulfuric acid solutions to etch the surface and form a micron-level rough structure, increasing the surface porosity to 65-80%, improving surface adhesion, and enhancing the adhesion performance of the catalyst layer 109. The concentration of the acid solution is 0.01~0.2 mol / L.

[0054] 2) Cleaning: After drying the titanium plate at a temperature of 50-100℃, the titanium plate is sandblasted with alumina sand to increase the surface roughness to 10-20μm.

[0055] 3) Mix carbon black powder and PTFE (polytetrafluoroethylene) emulsion uniformly at a mass ratio of 1: (1~3), and disperse them ultrasonically in 95% ethanol solution to form a uniform slurry.

[0056] 4) Immerse the carbon paper in the mixed slurry of step 3) above for 3-6 minutes, remove it and dry it at 100-110℃, then cold press it at 1-5MPa for 1-5 minutes. Repeat this step 3-5 times to obtain a uniform and smooth coating.

[0057] 5) Place the treated titanium plate horizontally on the workbench, and lay the coated carbon paper flat on the titanium plate, ensuring that there are no wrinkles or bubbles.

[0058] 6) Put the "carbon paper-titanium plate" sandwich between the heating plates of the hot press, start the press, the initial pressure is about 5MPa, and start the vacuum pump, the vacuum degree is about 10KPa, and the heating plate is also gradually heated, the target temperature range is 300~450℃, after reaching the target temperature, the pressure is gradually increased to 12~16MPa, and the highest is not more than 20MPa, the pressure maintaining and heat preservation time is 15~45min.

[0059] 7) After the pressure maintaining and heat preservation is finished, the heater is turned off, the pressure is reduced to 4~5MPa, and the pressure is released after natural cooling to 100℃ or less, and finally the composite cathode sheet is obtained.

[0060] 8) The treated cathode sheet is cut and curled, and the interface of the curled cylinder is cleaned and polished, and the cylinder is laser welded into a cylinder in an inert environment of helium or argon, and the upper end face of the cylinder is welded to the top, and finally a single-tube gas diffusion electrode with an open lower end is obtained.

[0061] Compared with the traditional flat plate electrode, the hollow cylindrical cathode tube 107 arranged in an array in the application can effectively increase the gas-liquid contact area, prolong the gas path, obtain longer gas residence time, make the reaction more sufficient, and the oxidation effect better, and the gas can uniformly penetrate out of the pores, and the aeration effect is better.

[0062] It should be noted that in the application, the water inlet 3 is configured as a horizontally arranged channel structure, and the water inlet mode and the gas inlet mode are vertically related, the rising gas can play a flushing role on the horizontal water inlet, which can not only ensure the uniform mixing and flow of wastewater in the reaction system, reduce the wastewater concentration difference along the horizontal direction, but also reduce the deposition of pollutants on the surface of the cathode when high current density is operated, thereby reducing the frequency of cathode pollution, and specifically: the wastewater flows horizontally outside the shell side of the cathode tube 107, and the gas (air or ozone) diffuses into the liquid from the tube side of the cathode tube 107, and the undiffused or unreacted gas naturally floats upward and escapes in the vertical direction outside the cathode tube 107, reducing the possibility of long-term retention of bubbles on the surface of the cathode tube 107 in a local area, because in the process of electrochemical reaction, hydrogen and OH - - ​The generation process of the bubbles and the precipitation process of the calcium and magnesium ions (if any in the water) are synchronized on the surface of the cathode tube 107, which causes the precipitation to adhere to the surface of the cathode tube 107, and the bubbles can effectively peel off the precipitation on the surface of the cathode tube 107, thereby reducing the risk of the dirt deposition on the surface of the cathode tube 107. On the other hand, the bubbles generated outside the cathode tube 107 have a dominant flow direction upward, so that the bubbles slide along the direction of the cylinder wall of the cathode tube 107 in the floating process. This flow mode is more conducive to the detachment and floating of the bubbles, and can flush the water flowing in the horizontal direction. Not only the gas-water mixing is more sufficient, but also the deposition of the pollutants on the outer surface of the vertically arranged cathode tube 107 is reduced.

[0063] The carbon-based filler 106 is arranged between the cathode and the anode 11, and the height ratio of the carbon-based filler 106 to the height of the reaction device 1 is 1:(3-5). Specifically, the water-permeable and air-permeable support plate 14 fixedly connected with the shell is arranged in the electrochemical reaction chamber 102, and the carbon-based filler 106 is loaded on the support plate 14. The carbon-based filler 106 has the adsorption performance of the activated carbon, can adsorb the pollutants in the water, has good electrical conductivity and can be used as an electrode to form a synergistic electrochemical reaction system with the original cathode and anode, and has catalytic performance and can catalyze the hydrogen peroxide and the ozone to generate hydroxyl radicals, thereby playing multiple roles, greatly improving the reaction efficiency of the device, and making the entire device have high processing efficiency, low energy consumption, and greatly reduced investment cost and processing cost. In the case of ozone input, the unreacted ozone at the cathode end is reacted with the hydrogen peroxide to generate free radicals after entering the electrochemical reaction chamber 102, and then oxidizes and degrades the organic matter, and the rest is floated to the carbon-based filler 106 for further reaction. The ozone is further catalyzed by the carbon-based filler 106 to generate hydroxyl radicals, so that the ozone utilization rate can reach more than 90%, and almost no secondary pollution is caused. In the embodiment, the particle size of the carbon-based filler 106 is 2-6 mm, which can not only maintain the mechanical framework of the carbon-based filler 106, but also has a large surface area.

[0064] It should be noted that the carbon-based filler 106 loaded on the support plate 14 can also improve the uneven distribution of the gas or liquid caused by the array layout of the cathode tube 107. Specifically, the gas is easily distributed unevenly between the dense cathode tubes 107, that is, the gas is excessive in some areas and insufficient in some areas. For the liquid, the flow state is complex, and dead zones are easily generated, which reduces the mass transfer efficiency. The carbon-based filler 106 filled between the cathode and the anode 11 forms a porous medium layer structure filter, which can force the liquid flow to be in a turbulent state and eliminate the flow dead zones.

[0065] Preferably, in order to enhance the conductivity and oxidation active sites of the carbon-based filler 106, the application adopts the impregnation-calcination method to dope sulfur / fluorine elements on the activated carbon substrate. Exemplarily, the sulfur / fluorine elements can be NaS and NaF respectively, and the mass ratio of the sulfur / fluorine elements to the activated carbon is 1:7.5~9. Due to the difference in electronegativity between the doped sulfur S / fluorine F atoms and carbon atoms C, the charge distribution of the activated carbon-based material changes. On the one hand, it can improve the capture / adsorption of pollutants and oxygen in water by the carbon-based filler 106, and improve the adsorption performance. On the other hand, the doped sulfur S / fluorine F atoms occupy part of the space positions of the carbon atoms, so that the carbon-based filler 106 obtains more active sites. The active sites can catalyze and accelerate the electrochemical reaction between the cathode and the anode 11, thereby improving the efficiency of the electrochemical oxidation reaction. Also, the sulfur S / fluorine F atoms can catalyze hydrogen peroxide and ozone to generate hydroxyl radicals respectively, thereby improving the catalytic oxidation efficiency. Moreover, the larger specific surface area and stronger adsorption capacity of the carbon-based filler 106 are also extremely beneficial to the removal of organic matter in water. Thirdly, sulfur S / fluorine F are both non-metallic elements, which are combined with carbon C non-metallic through C-S bond and C-F bond, and the stability of the material is good. In the preferred example, the carbon-based filler 106 can act as a catalyst for electrochemical oxidation and catalytic oxidation. The combination of sulfur and fluorine atoms produces a synergistic effect, increases the active sites on the carbon surface, and improves the catalytic performance. The catalytic performance of the carbon-based filler 106 is better than that of the conventional noble metal-doped catalyst, and the performance is more stable. Moreover, the carbon-based filler 106 can also conduct electricity, act as a third electrode, promote the electrochemical reaction between the cathode and the anode, improve the efficiency of the electrochemical reaction, and obtain better treatment effect at a lower cost.

[0066] The anode 11 includes an anode conductive plate which is roughly matched with the shape of the cathode conductive plate 7, and one side of the anode conductive plate is fixedly connected with an anode terminal. When power is turned on, the anode 11 can directly oxidize pollutants or indirectly generate other oxidants (such as •OH) to further synergistically degrade pollutants. The anode conductive plate adopts a titanium-based coating composite material, the substrate is titanium, and the porosity is increased by using the same etching method as the cathode. The surface coating is an oxide of a noble metal such as ruthenium, iridium, and tantalum. The mass ratio of the oxides of ruthenium, iridium, and tantalum is (2~4):(1.2~3.5):1. The use of noble metal oxides can greatly improve the electrocatalytic activity.

[0067] It should be noted that in the application, the carbon-based filler 106 is provided with a piece of net-like conductive separation layer 15. The net-like conductive separation layer 15 is connected with the electrochemical reaction shell through buckling, and can be disassembled at any time. The distance between the anode 11 and the net-like conductive separation layer 15 is about 8-12 mm. The carbon-based filler 106 is in close proximity to the cathode and anode 11, so that the active substances (hydroxyl radicals, etc.) generated by the cathode and anode 11 can act on the surface of the carbon-based filler 106 and the adsorbed pollutants in a moment and in close proximity. The cathode end and the anode 11 end are connected with a direct current power supply. The current density is 100~250A / m 2 .

[0068] Referring again to Figure 1 , the gas-water separation chamber 103 is fixedly connected to the second stage flange 105, the top of the gas-water separation chamber 103 is provided with an exhaust port 5, and the sidewall of the gas-water separation chamber 103 is provided with a water outlet 6. Further, the gas-water separation chamber 103 is further provided with a separation layer plate 13, which is horizontally arranged in the gas-water separation chamber 103 and arranged below the water outlet 6. Exemplarily, the separation layer plate 13 is made of a material with good water permeability and air permeability, such as a fiber bundle or cotton, palm, etc. By arranging the separation layer plate 13, the water flow rising speed can be slowed down, the water flow can be stably overflowed, and the tail gas flow can be smoothly upward, thereby achieving a good gas-water separation effect.

[0069] The anode 11 is connected between the upper and lower flanges of the second stage flange 105, and the connection mode of the second stage flange 105 is consistent with that of the first stage flange 104, which will not be described herein again.

[0070] The application will be further described in detail below in conjunction with the embodiments. It should be understood that the following embodiments are only used to further illustrate the application, and cannot be understood as a limitation on the protection scope of the application. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the application all belong to the protection scope of the application. The specific process parameters in the following examples are only one example in the appropriate range, i.e., those skilled in the art can select within the appropriate range according to the description herein, and are not limited to the specific values in the following examples.

[0071] Embodiment 1

[0072] The gas-liquid mixed electrochemical oxidation device provided by the application is used to treat a certain landfill leachate (inlet water pH = 7.8, COD = 3515 mg / L, ammonia nitrogen = 1345 mg / L, conductivity = 43120 μS / cm, Cl - = 16740 mg / L), and ozone gas is introduced into the device;

[0073] In this embodiment, the height of the cathode tube 107 in the tubular cathode group 8 is 20 mm, the outer diameter is 10 mm, and the wall thickness is about 2 mm;

[0074] The filling height of the carbon-based filler 106 is 1:3 of the height of the reaction device 1, and the particle size of the activated carbon in the carbon-based filler 106 is about 5 mm, and the mass ratio of sulfur / fluorine element to activated carbon is 1:9.

[0075] The anode conductive plate is made of a titanium-based coating composite material, the substrate is titanium, the surface coating is an oxide of a noble metal such as ruthenium, iridium, and tantalum, and the mass ratio of ruthenium oxide, iridium oxide, and tantalum oxide is 2:3:1.

[0076] The removal effect data of the device of the embodiment in treating landfill leachate is shown in Table 1.

[0077] Table 1 Experimental data of the electrochemical oxidation device in treating landfill leachate

[0078]

[0079] Example 2

[0080] The difference between Example 2 and Example 1 is that:

[0081] In this embodiment, the ratio of the filling height of the carbon-based filler 106 to the height of the reaction device is 1:4.

[0082] The removal effect data of the device of the embodiment in treating landfill leachate is shown in Table 2.

[0083] Table 2 Experimental data of the electrochemical oxidation device in treating landfill leachate

[0084]

[0085] As can be seen from Table 1 and Table 2, the treatment effect is good when the device is used to treat landfill leachate, and the effluent can meet the standard of Table 3 of “Standard for Pollution Control on Domestic Waste Landfill Sites” (GB 16889-2024) (in Table 3, the effluent COD is ≤60 mg / L, and ammonia nitrogen is ≤8 mg / L), which can meet the discharge standard. It can be seen that, compared with Example 2, the filling amount of the carbon-based filler in Example 1 is more, and the catalysis, adsorption and electrochemical reaction efficiency is higher.

[0086] Example 3

[0087] The difference between Example 3 and Example 1 is that air is introduced into the device, and the removal effect data of the landfill leachate is shown in Table 3.

[0088] Table 3 Experimental data of the electrochemical oxidation device in treating landfill leachate

[0089]

[0090] As can be seen from Table 3, the device does not introduce ozone but air, and the cathode can still efficiently capture oxygen therein and produce hydrogen peroxide on the outer surface of the cathode by reduction reaction. The treatment effect slightly decreases compared with the introduction of ozone, but the effluent quality can still meet the standard of Table 2 of “Standard for Pollution Control on Domestic Waste Landfill Sites” (GB 16889-2024) (in Table 2, the effluent COD is ≤100 mg / L, and ammonia nitrogen is ≤25 mg / L), which can also meet the discharge standard.

[0091] Comparative Example 1

[0092] The difference between the present comparative example 1 and the example 1 is that the carbon-based filler 106 is not arranged in the electrochemical reaction chamber 102 of the reaction device 1, and the rest is the same as the example 1, and the removal effect data is shown in Table 4:

[0093] Table 4 Comparative data of the present comparative example 1 and the example 1

[0094]

[0095] As can be seen from Table 4, the carbon-based filler 106 is not arranged in the electrochemical reaction chamber 102, the catalyst for electrochemical oxidation is lacked, and there is no capture / adsorption function for pollutants and oxygen in water, and the electrochemical reaction with the cathode and the anode is also lacked, so that the final removal effect is obviously decreased, resulting in poor treatment effect on the landfill leachate, and the effluent is not up to standard and cannot be discharged.

[0096] Comparative example 2

[0097] The difference between the present comparative example 2 and the example 1 is that the reaction device is used to treat the landfill leachate without power supply or electrode, and the rest is the same as the example 1, and the removal effect data is shown in Table 5:

[0098] Table 5 Comparative data of the present comparative example 2 and the example 1

[0099]

[0100] As can be seen from Table 5, the reaction device is not powered or has no electrode, and the device is equivalent to a simple ozone catalytic oxidation device or a simple filler adsorption tower. However, in high-salinity wastewater, ozone catalytic oxidation and filler adsorption will be inhibited by salt, and the removal effect will be greatly decreased. Therefore, the treatment effect of the present comparative example 2 on the landfill leachate is very poor, not only the COD removal rate is low, but also the ammonia nitrogen removal effect is basically zero, and the effluent cannot meet the standard and cannot be discharged.

[0101] Comparative example 3

[0102] The difference between the present comparative example 3 and the example 1 is that the cathode is a conventional flat titanium cathode, and the gas holes are uniformly arranged on the cathode, which can permeate gas but cannot permeate water molecules, and the rest is the same as the example 1, and the removal effect data is shown in Table 6:

[0103] Table 6 Comparative data of the present comparative example 3 and the example 1

[0104]

[0105] As can be seen from Table 6, the cathode adopts a conventional flat titanium cathode, the gas-liquid contact area is small, the gas residence time is greatly shortened compared with the tubular cathode group 8, the reaction cannot be fully carried out, the oxidation effect is poor, and the treatment effect on the landfill leachate is poor, which cannot meet the effluent standard requirements and cannot be discharged.

[0106] Comparative Example 4

[0107] The difference between the present comparative example 4 and Example 1 is that the carbon-based filler 106 in the present comparative example adopts a conventional activated carbon filler, and no other elements are doped on the activated carbon, and the others are the same as Example 1. The removal effect data are shown in Table 7:

[0108] Table 7 Comparative data of Comparative Example 4 and Example 1

[0109]

[0110] As can be seen from Table 7, the conventional activated carbon filler is used in the present comparative example, and no sulfur / flourine atoms are doped, the active sites on the filler are few, only the conventional adsorption and the role as a conductive electrode, and then the treatment effect on the landfill leachate is poor, and the effluent COD and ammonia nitrogen cannot meet the requirements and cannot be discharged.

[0111] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples, the above examples and descriptions in the specification are only preferred examples of the present application, and are not used to limit the present application, various changes and improvements of the present application can be made without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A gas-liquid hybrid electrochemical oxidation device, characterized by, The reaction device (1) is connected to the upper part of the support (2), and the reaction device (1) is sequentially divided into a gas buffer chamber (101), an electrochemical reaction chamber (102) and a gas-water separation chamber (103) from bottom to top. The gas buffer chamber (101) is separated from the electrochemical reaction chamber (102) by a cathode, and the electrochemical reaction chamber (102) is separated from the gas-water separation chamber (103) by an anode. A water inlet (3) is arranged at the lower end of the side wall of the electrochemical reaction chamber (102), a gas inlet (4) is arranged at the bottom of the gas buffer chamber (101), and an exhaust port (5) is arranged at the top of the gas-water separation chamber (103), and a water outlet (6) is arranged on the side wall. The gas buffer chamber (101) and the electrochemical reaction chamber (102) are connected through a first-stage flange (104), and a cathode is arranged between the upper and lower flanges of the first-stage flange (104). The cathode comprises a cathode conductive plate (7) and a tubular cathode group (8), and one side of the cathode conductive plate (7) is protruded to form a cathode terminal post (10). The cathode is located below the water inlet (3). The tubular cathode group (8) is arranged by a plurality of cathode tubes (107), the cathode tube (107) is a hollow cylindrical structure, the upper end surface of the cathode tube (107) is capped, and the upper end surface is 8-15 mm higher than the cathode conductive plate (7). The lower end surface of the cathode tube (107) is not capped, and is flush with the lower bottom surface of the cathode conductive plate (7) and is in communication with the gas buffer chamber (101). The tube wall of the cathode tube (107) comprises a gas diffusion layer (108), a catalytic layer (109) and a current collector layer (110) arranged from inside to outside. The electrochemical reaction chamber (102) and the gas-water separation chamber (103) are connected through a second-stage flange (105), and an anode (11) is arranged between the upper and lower flanges of the second-stage flange (105). The electrochemical reaction chamber (102) is filled with carbon-based fillers (106), and the carbon-based fillers (106) are located below the anode (11) and above the water inlet (3).

2. The gas-liquid hybrid electrochemical oxidation device according to claim 1, characterized in that, The reaction device (1) is a cylindrical structure, and the height-diameter ratio is (1-4):

1.

3. The gas-liquid hybrid electrochemical oxidation device according to claim 1, wherein, The axial center distance between adjacent two cathode tubes (107) is 12-20 mm, the height of the cathode tube (107) is 15-20 mm, the outer diameter is 8-10 mm, the wall thickness is 1-2 mm, and the cathode tube (107) is cast and fixed on the cathode conductive plate (7).

4. The gas-liquid hybrid electrochemical oxidation device of claim 1, wherein, In the electrochemical reaction chamber (102), a fixed water-permeable and air-permeable support plate (14) is arranged above the water inlet (3), and a detachable mesh conductive separation layer (15) is arranged below the anode (11). The distance between the mesh conductive separation layer (15) and the anode (11) is 8-12 mm, the mesh conductive separation layer (15) is connected with the electrochemical reaction chamber (102) through buckling, and the carbon-based fillers (106) are filled between the support plate (14) and the conductive separation layer (15).

5. The gas-liquid hybrid electrochemical oxidation device of claim 1, wherein, The filling height of the carbon-based fillers (106) to the height of the reaction device (1) is 1:(3-5).

6. The gas-liquid hybrid electrochemical oxidation device of claim 1, wherein, The carbon-based filler (106) is sulfur and fluorine co-doped carbon particles with a particle size of 2-6 mm.

7. The gas-liquid hybrid electrochemical oxidation device of claim 1, wherein, The first-stage flange (104) and the upper and lower flanges of the second-stage flange (105) are fixedly connected by bolts and nuts (12), and sealing gaskets (9) are arranged between the two flanges facing each other.

8. The gas-liquid hybrid electrochemical oxidation device of claim 1, wherein, The gas-water separation chamber (103) is provided with a separation layer plate (13) arranged horizontally below the water outlet (6), and the separation layer plate (13) is made of a water-permeable and air-permeable material.

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