Ammonia nitrogen wastewater electrocatalytic electrode, preparation method, electrode system and use method

Abstract

This invention relates to the field of wastewater treatment technology, and more particularly to an electrocatalytic electrode for ammonia nitrogen wastewater, comprising an ammonia nitrogen catalytic oxidation anode and a nitrate nitrogen reduction cathode. The ammonia nitrogen catalytic oxidation anode comprises a Ti2 substrate; the Ti2 substrate is a hollow cylindrical structure with an open top and closed bottom, and its outer surface is coated with a catalytic oxidation coating, while its inner surface is coated with an anode ClO·capture coating. The nitrate nitrogen reduction cathode comprises a porous biomass nano-carbon felt; the porous biomass nano-carbon felt is a hollow cylindrical structure with an open top and closed bottom, and its outer surface is coated with a cathode reduction coating, while its inner surface is coated with a cathode ClO·capture coating. This invention also discloses its preparation method, an electrode system including the electrode, and a method for using the electrode system. This invention can reduce the selectivity of nitrate nitrogen at the source, achieving complete removal of nitrogen from wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an electrocatalytic electrode for ammonia nitrogen wastewater, its preparation method, electrode system, and its usage. Background Technology

[0002] The treatment of high-salinity, high-concentration ammonia nitrogen wastewater is a challenging problem in wastewater treatment. Both its high salinity and high ammonia nitrogen concentration are biotoxic, rendering biological methods ineffective. The effectiveness of ammonia stripping is influenced by the ammonia nitrogen concentration and pH of the wastewater; it is most effective when the ammonia nitrogen concentration is greater than 3000 mg / L and the pH is greater than 10. However, ammonia stripping generates stripping exhaust gas that requires treatment; pH adjustment and stripping power costs are not low; and ammonia stripping is ineffective at removing ammonia nitrogen concentrations below 1000 mg / L, failing to meet effluent standards. High salinity implies high conductivity, which reduces the heat generation side effects of electrocatalysis, thereby lowering its operating costs. Furthermore, electrocatalysis can adapt to a wide range of pollutant concentrations, with effluent ammonia nitrogen levels approaching 0 mg / L, and no upper limit on treatable ammonia nitrogen concentrations.

[0003] However, electrocatalytic treatment of ammonia nitrogen wastewater also has significant drawbacks. The products of electrocatalytic oxidation of ammonia nitrogen include nitrogen gas, nitrite nitrogen, and nitrate nitrogen. Ideally, the nitrogen gas would be converted into non-toxic nitrogen gas and released into the atmosphere. However, excessive oxidation leads to ammonia nitrogen being oxidized into nitrite nitrogen and then into nitrate nitrogen upon contact with air, ultimately resulting in high-salt, high-nitrate nitrogen wastewater. Compared to high-salt, high-ammonia nitrogen wastewater, the electrocatalytic effect on high-salt, high-nitrate nitrogen wastewater is poor, requiring more power consumption and longer operating time per unit of nitrate nitrogen removal. Therefore, product selectivity is crucial in the electrocatalytic treatment of ammonia nitrogen wastewater. Furthermore, indirect oxidation by ClO· is the main mechanism for ammonia nitrogen oxidation removal, but excessive ClO· can also lead to over-oxidation, resulting in higher selectivity for nitrate nitrogen. Summary of the Invention

[0004] The purpose of this invention is to provide an electrocatalytic electrode for ammonia nitrogen wastewater, a preparation method, an electrode system, and a method of use, so as to solve the technical problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An electrocatalytic electrode for ammonia nitrogen wastewater includes an ammonia nitrogen catalytic oxidation anode and a nitrate nitrogen reduction cathode. The ammonia nitrogen catalytic oxidation anode comprises a Ti2 substrate. The Ti2 substrate has a hollow cylindrical structure with an open top and a closed bottom, and its outer surface is provided with a catalytic oxidation coating, while its inner surface is provided with an anode ClO·capture coating. The nitrate nitrogen reduction cathode comprises a porous biomass nanocarbon felt. The porous biomass nanocarbon felt has a hollow cylindrical structure with an open top and a closed bottom, and its outer surface is provided with a cathode reduction coating, while its inner surface is provided with a cathode ClO·capture coating.

[0007] Furthermore, the catalytic oxidation coating is formed by spraying a catalytic oxidation coating onto the surface of a Ti2 substrate; the catalytic oxidation coating is a mixed solution obtained by mixing RuCl3, IrCl4, and ethylene glycol in a mass ratio of 1:1:1.

[0008] Furthermore, the anodic ClO·capture coating is formed by spraying anodic ClO·capture paint onto the surface of the Ti2 substrate; the anodic ClO·capture paint is a mixed solution obtained by mixing CeO2 and ethylene glycol at a mass ratio of 1.5:1.

[0009] Furthermore, the cathode reduction coating is formed by applying cathode reduction coating material to the surface of porous biomass nano-carbon felt; the cathode reduction coating is a mixed solution obtained by mixing reduced nickel powder, reduced copper powder, and conductive adhesive in a mass ratio of 3:1:9.

[0010] Furthermore, the cathode ClO·capture coating is formed by applying the cathode ClO·capture coating to the surface of the porous biomass nano carbon felt; the cathode ClO·capture coating is a mixed solution obtained by mixing CeO2 and conductive adhesive at a mass ratio of 35:1.

[0011] The preparation method of the electrocatalytic electrode for ammonia nitrogen wastewater includes the following steps:

[0012] Preparation of S1 ammonia nitrogen catalytic oxidation anode:

[0013] (1) Catalytic oxidation coating spraying: The catalytic oxidation coating is sprayed onto one side of the cut and pretreated Ti2 substrate;

[0014] (2) Anode ClO·capture coating spraying: Anode ClO·capture coating is sprayed on the other side of the Ti2 substrate in (1) to obtain the anode material;

[0015] (3) Preparation of ammonia nitrogen catalytic oxidation anode: The anode material after coating drying and curing is rolled into a cylindrical structure with an open top, closed bottom, hollow interior, and catalytic oxidation coating facing outwards to obtain the ammonia nitrogen catalytic oxidation anode;

[0016] Preparation of S2 nitrate nitrogen reduction cathode:

[0017] (1) Preparation of porous biomass nano carbon felt: Biomass raw materials are crushed and compacted to form a 2mm thick carbon felt, which is then carbonized at high temperature to obtain porous biomass nano carbon felt.

[0018] (2) Preparation of cathodic reduction coating: The cathodic reduction coating solution is uniformly coated on one side of the porous biomass nano carbon felt obtained in (1);

[0019] (3) Preparation of cathode ClO·capture coating: The cathode ClO·capture coating is uniformly coated on the other surface of the porous biomass nano carbon felt to obtain the cathode material;

[0020] (4) Preparation of nitrate nitrogen reduction cathode: The cathode material after coating drying and curing is rolled into a cylindrical structure with an open top, a closed bottom, a hollow interior, and the cathode reduction coating facing outwards to obtain the nitrate nitrogen reduction cathode.

[0021] Furthermore, the biomass is peanut shells.

[0022] Furthermore, the high-temperature carbonization is carried out in a nitrogen atmosphere at a temperature of 700°C for 5 hours.

[0023] An electrode system includes a reactor, an anode module, a cathode module, an anode circulation module, a cathode circulation module, and a control module;

[0024] The anode module and cathode module are located inside the reactor; the anode module includes ammonia nitrogen catalytic oxidation anodes among the multiple electrodes; the multiple ammonia nitrogen catalytic oxidation anodes are connected by an anode Ti2 rod;

[0025] The cathode module includes a plurality of nitrate nitrogen reduction cathodes among the electrodes; the plurality of nitrate nitrogen reduction cathodes are connected by a cathode Ti2 rod;

[0026] The anode circulation module comprises multiple modules, each connected to a specific ammonia nitrogen catalytic oxidation anode. Each module includes an anode inlet pipe, an anode circulation pump, an anode outlet pipe, and an anode solenoid valve. The anode inlet pipe is connected to the anode circulation pump, with its other end extending upwards and entering the ammonia nitrogen catalytic oxidation anode from the top. The anode circulation pump is connected to the anode inlet pipe. One end of the anode outlet pipe is connected to the bottom of the ammonia nitrogen catalytic oxidation anode, and the other end is located inside the reactor. The anode solenoid valve is connected to the anode outlet pipe.

[0027] The cathode circulation module comprises multiple units, each connected to a nitrate nitrogen reduction cathode. Each unit includes a cathode inlet pipe, a cathode circulation pump, a cathode outlet pipe, and a cathode solenoid valve. The cathode inlet pipe and cathode circulation pump are connected at one end, with the other end extending upwards and entering the nitrate nitrogen reduction cathode from its top. The cathode circulation pump is connected to the cathode inlet pipe. One end of the cathode outlet pipe is connected to the bottom of the ammonia nitrogen catalytic oxidation cathode, and the other end is located inside the reactor. The cathode solenoid valve is connected to the cathode outlet pipe.

[0028] The control module includes a PLC control system, a DC regulated power supply, an online ClO· concentration monitoring probe, an online ammonia nitrogen concentration monitoring probe, and an ultraviolet lamp. The DC regulated power supply is connected to one of the ammonia nitrogen catalytic oxidation anodes and one of the nitrate nitrogen reduction cathodes via wires. The online ClO· concentration monitoring probe is connected to the anode Ti2 rod. The online ammonia nitrogen concentration monitoring probe is connected to the cathode Ti2 rod. The ultraviolet lamp is fixedly mounted on the top surface of each ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode. The PLC control system is electrically connected to the DC regulated power supply, the online ClO· concentration monitoring probe, and the online ammonia nitrogen concentration monitoring probe.

[0029] The ultraviolet lamps are fixedly mounted on the top surface of each ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode, and are electrically connected to the PLC control system.

[0030] The method of using the electrode system includes the following steps:

[0031] S1 Start-up: Wastewater is introduced into the reactor and the bottom mixer is turned on to ensure that the wastewater is in full contact with the ammonia nitrogen catalytic oxidation anode of the anode module and the nitrate nitrogen reduction cathode of the cathode module.

[0032] S2 Electrocatalysis: When the DC regulated power supply is turned on, the electrocatalytic state is entered. The catalytic oxidation coating on the outside of the ammonia nitrogen catalytic oxidation anode and the cathode reduction coating on the outside of the nitrate nitrogen reduction cathode come into contact with the ammonia nitrogen wastewater, thereby achieving nitrogen removal from the wastewater.

[0033] S3 Capture: When the ClO· concentration online monitoring probe detects that the ClO· concentration in the wastewater exceeds the upper limit, the signal is transmitted to the PLC control system. The PLC control system shuts off the DC regulated power supply and starts the circulating water pumps of the anode and cathode circulation modules, allowing wastewater to flow into the ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode. When the water is full, the anode and cathode solenoid valves are activated, causing the ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode to enter a circulation state with water entering from the top and exiting from the bottom. At the same time, the flow difference between the circulating water pump and the outlet valve is controlled to ensure that each electrode is in a full water state and enters the ClO· capture state. In the ClO· capture state, the anode ClO· capture coating on the ammonia nitrogen catalytic oxidation anode and the cathode ClO· capture coating on the nitrate nitrogen reduction cathode come into contact with the wastewater, capturing ClO·, reducing the ClO· concentration in the wastewater, and preventing excessive oxidation of ammonia nitrogen to generate nitrate nitrogen.

[0034] S4 Reduction: When the ClO· concentration online monitoring probe detects that the ClO· concentration in the wastewater is below the lower limit, the signal is transmitted to the PLC control system, and the ClO· capture coating enters the reduction state. In the ClO· capture coating reduction state, the PLC control system shuts down the anode circulation pump and the cathode circulation pump, and closes the anode solenoid valve and the cathode solenoid valve after a delay, draining the wastewater in the electrode cylinder. After draining, the top ultraviolet lamp is turned on, allowing the anode ClO· capture coating and the cathode ClO· capture coating to fully contact the ultraviolet light, releasing ClO· and realizing the reduction of the ClO· capture coating. After 30 minutes, the ultraviolet lamp is turned off, the DC regulated power supply is started, and the system returns to the electrocatalytic state.

[0035] S5: This cycle repeats until the online ammonia nitrogen concentration monitoring probe on the cathode detects that the ammonia nitrogen concentration in the wastewater reaches the effluent standard, and transmits the signal to the PLC control system. The DC regulated power supply then shuts down, the bottom mixer closes, and the system enters a shutdown state. The advantages of this invention compared to existing technologies are:

[0036] The advantages of this invention compared to the prior art are as follows:

[0037] 1. In the electrode of the present invention, the oxidation capacity of the anode is controlled by the selection of the catalytic oxidation coating material, preventing ammonia nitrogen from being converted into nitrate nitrogen due to anode peroxidation. The ClO. capture coating captures excess ClO., preventing ammonia nitrogen from being oxidized into nitrate nitrogen by excess ClO., thereby reducing the selectivity of nitrate nitrogen from the source. The cathode reduction coating reduces the small amount of nitrate nitrogen generated by peroxidation into nitrogen gas, thereby achieving complete removal of nitrogen from wastewater.

[0038] 2. This invention increases electron channels and functional groups by preparing porous biomass nano-carbon felt as a cathode material, and improves the conductivity of porous biomass nano-carbon felt through high-temperature carbonization, thereby enhancing the processing capacity of the cathode plate.

[0039] 3. In the electrode system of the present invention, multiple ammonia nitrogen catalytic oxidation anodes and multiple nitrate nitrogen reduction cathodes are respectively composed of an anode module and a cathode module, which, together with a control module, a cathode circulation module, and an anode circulation module, perform electrocatalysis and ClO. capture, thereby achieving complete denitrification and significantly reducing the selectivity of nitrate nitrogen. At the same time, after ClO. capture, the ClO. capture coating can be reduced to prepare for the next electrocatalysis. The wastewater treatment effect is good, the cost is low, and it has good application prospects. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the ammonia nitrogen catalytic oxidation anode of the present invention;

[0041] Figure 2 This is a cross-sectional view of the ammonia nitrogen catalytic oxidation anode of the present invention;

[0042] Figure 3 This is a schematic diagram of the structure of the nitrate nitrogen reduction cathode of the present invention.

[0043] Figure 4 This is a cross-sectional view of the nitrate nitrogen reduction cathode of the present invention.

[0044] Figure 5 This is a schematic diagram of the electrode system of the present invention;

[0045] Figure 6 This is a schematic diagram of the connection structure between the anode module and the cathode module of the present invention;

[0046] Figure 7 This is a schematic diagram of the connection structure of the anode circulation module of the present invention.

[0047] Figure 8 This is a schematic diagram of the connection structure of the cathode circulation module of the present invention;

[0048] 100-Anode Module;

[0049] 101-Ammonia nitrogen catalytic oxidation anode; 1011-Ti2 substrate; 1012-Catalytic oxidation coating; 1013-Anode ClO·capture coating; 102-Anode Ti2 rod;

[0050] 200-Cathode Module;

[0051] 201-Nitrogen reduction cathode; 2011-Porous biomass nano-carbon felt; 2012-Cathode reduction coating; 2023-Cathode ClO·capture coating; 202-Cathode Ti2 rod;

[0052] 300-reactor;

[0053] 400 - Anode circulation module; 401 - Anode inlet pipe; 401 - Anode circulation pump; 401 - Anode outlet pipe; 401 - Anode solenoid valve;

[0054] 500 - Cathode circulation module; 501 - Cathode inlet pipe; 502 - Cathode circulation pump; 503 - Cathode outlet pipe; 504 - Cathode solenoid valve;

[0055] 600 - Control module; 601 - PLC control system; 602 - DC regulated power supply; 603 - ClO· concentration online monitoring probe; 604 - Ammonia nitrogen concentration online monitoring probe;

[0056] 700-UV lamp. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the invention, and these aspects of the invention can be implemented even without these specific details.

[0058] Example 1

[0059] like Figure 1-4 As shown, an electrocatalytic electrode for ammonia nitrogen wastewater includes an ammonia nitrogen catalytic oxidation anode 101 and a nitrate nitrogen reduction cathode 201. The ammonia nitrogen catalytic oxidation anode 101 comprises a Ti2 substrate. The Ti2 substrate is a hollow cylindrical structure with an open top surface and a closed bottom surface. Its outer surface is provided with a catalytic oxidation coating 1012, and its inner surface is provided with an anode ClO·capture coating 1013. The nitrate nitrogen reduction cathode 201 comprises a porous biomass nano-carbon felt 2011. The porous biomass nano-carbon felt 2011 is a hollow cylindrical structure with an open top surface and a closed bottom surface. Its outer surface is provided with a cathode reduction coating 2012, and its inner surface is provided with a cathode ClO·capture coating 2023.

[0060] The catalytic oxidation coating 1012 is formed by spraying a catalytic oxidation coating onto the surface of a Ti2 substrate; the catalytic oxidation coating is a mixed solution obtained by mixing RuCl3, IrCl4, and ethylene glycol in a mass ratio of 1:1:1.

[0061] The anodic ClO·capture coating 1013 is formed by spraying anodic ClO·capture paint onto the surface of Ti2 substrate; the anodic ClO·capture paint is a mixed solution obtained by mixing CeO2 and ethylene glycol at a mass ratio of 1.5:1.

[0062] The cathode reduction coating 2012 is formed by applying cathode reduction coating to the surface of porous biomass nano carbon felt 2011; the cathode reduction coating 2012 is a mixed solution obtained by mixing 200 mesh reduced nickel powder, 200 mesh reduced copper powder and conductive adhesive in a mass ratio of 3:1:9.

[0063] The cathode ClO·capture coating 2023 is formed by applying the cathode ClO·capture coating 2023 to the surface of the porous biomass nano carbon felt 2011; the cathode ClO·capture coating 2023 is a mixed solution obtained by mixing CeO2 and conductive adhesive at a mass ratio of 35:1.

[0064] The preparation method of the electrocatalytic electrode for ammonia nitrogen wastewater includes the following steps:

[0065] Preparation of S1 ammonia nitrogen catalytic oxidation anode 101:

[0066] (1) Catalytic oxidation coating 1012 spraying: After cutting and pretreatment, Ti2 substrate 1011 is formed into an open top surface, closed bottom surface, hollow internal cylindrical structure with a thickness of 1mm. Then, catalytic oxidation coating is sprayed on one side of Ti2 substrate 1011; the layer thickness is controlled at 0.8±0.1μm, and it is dried in a tube furnace at 120℃ for 30min; the cycle is repeated 3 times; the spraying medium is nitrogen gas at 0.4Mpa and the flow rate is 0.5mL / min; the spraying distance is 12cm; the substrate temperature is 90±5℃; the relative humidity and temperature of the environment are 20% and 25℃, respectively.

[0067] (2) Anode ClO·capture coating 1013 spraying: Anode ClO·capture coating is sprayed on the other side of Ti2 substrate 1011 in (1) to obtain anode material; the layer thickness is controlled at 0.8±0.1μm, and dried in a tube furnace at 120℃ for 30min; cycled 3 times; the spraying medium is nitrogen gas at 0.4Mpa and the flow rate is 0.5mL / min; the spraying distance is 12cm; the substrate temperature is 90±5℃; the relative humidity and temperature of the environment are 20% and 25℃, respectively;

[0068] (3) Preparation of ammonia nitrogen catalytic oxidation anode 101: The anode material after coating drying and curing is rolled into a cylindrical structure with an open top surface, a closed bottom surface, a hollow interior, and the catalytic oxidation coating 1012 facing outwards. The joints are welded for corrosion protection, and a sealing ring is set at the welded joints to obtain ammonia nitrogen catalytic oxidation anode 101.

[0069] Preparation of S2 nitrate nitrogen reduction cathode 201:

[0070] (1) Preparation of porous biomass nano carbon felt 2011: Peanut shell biomass raw material was crushed and compacted to form a 2mm thick carbon felt, which was carbonized at 700℃ for 5h in a nitrogen environment to obtain porous biomass nano carbon felt 2011, and cut into an unfolded shape of a cylindrical structure with an open top, a closed bottom, and a hollow interior.

[0071] (2) Preparation of cathode reduction coating 2012: The cathode reduction coating 2012 solution was uniformly coated on one side of the porous biomass nano carbon felt 2011 obtained in (1);

[0072] (3) Preparation of cathode ClO·capture coating 2023: The cathode ClO·capture coating is uniformly coated on the other surface of porous biomass nano carbon felt 2011 to obtain the cathode material;

[0073] (4) Preparation of nitrate nitrogen reduction cathode 201: The cathode material after coating drying and curing is rolled into a cylindrical structure with an open top, a closed bottom, a hollow interior, and the cathode reduction coating 2012 facing outward. The joint is welded for corrosion protection, and a sealing ring is set at the weld to obtain nitrate nitrogen reduction cathode 201.

[0074] like Figure 5-8 As shown, an electrode system includes a reactor 300, an anode module 100, a cathode module 200, an anode circulation module 400, a cathode circulation module 500, and a control module 600.

[0075] The reactor 300 is vertically arranged, and a mixer is provided on its inner bottom surface;

[0076] The anode module 100 and cathode module 200 are disposed within the reactor 300; the anode module 100 includes a plurality of ammonia nitrogen catalytic oxidation anodes 101; the plurality of ammonia nitrogen catalytic oxidation anodes 101 are connected to each other by anode Ti2 rods 102;

[0077] The cathode module 200 includes a plurality of nitrate reduction cathodes 201; the plurality of nitrate reduction cathodes 201 are connected to each other by cathode Ti2 rods 202;

[0078] The anode circulation module 400 is provided in multiple units, and each anode circulation module 400 is connected to each ammonia nitrogen catalytic oxidation anode 101. Each module includes an anode inlet pipe 401, an anode circulation pump 401, an anode outlet pipe 401, and an anode solenoid valve 401. One end of the anode inlet pipe 401 is connected to the anode circulation pump 401, and the other end extends upward and enters the interior of the ammonia nitrogen catalytic oxidation anode 101 from the top. The anode circulation pump 401 is connected to the anode inlet pipe 401. One end of the anode outlet pipe 401 is connected to the bottom of the ammonia nitrogen catalytic oxidation anode 101, and the other end is located inside the reactor 300. The anode solenoid valve 401 is connected to the anode outlet pipe 401.

[0079] The cathode circulation module 500 comprises multiple modules, each connected to a nitrate reduction cathode 201. Each module includes a cathode inlet pipe 501, a cathode circulation pump 502, a cathode outlet pipe 503, and a cathode solenoid valve 504. One end of the cathode inlet pipe 501 is connected to the cathode circulation pump 502, and the other end extends upward and enters the nitrate reduction cathode 201 from its top. The cathode circulation pump 502 is connected to the cathode inlet pipe 501. One end of the cathode outlet pipe 503 is connected to the bottom of the nitrate reduction cathode 201, and the other end is located inside the reactor 300. The cathode solenoid valve 504 is connected to the cathode outlet pipe 503.

[0080] The control module 600 includes a PLC control system 601, a DC regulated power supply 602, an online ClO· concentration monitoring probe 603, and an online ammonia nitrogen concentration monitoring probe 604. The DC regulated power supply 602 is connected to one of the ammonia nitrogen catalytic oxidation anodes 101 and one of the nitrate nitrogen reduction cathodes 201 via wires. The ClO· concentration online monitoring probe 603 is connected to the anode Ti2 rod 102. The ammonia nitrogen concentration online monitoring probe 604 is connected to the cathode Ti2 rod 202. The ultraviolet lamp 700 is fixedly installed on the top surface of each ammonia nitrogen catalytic oxidation anode 101 and nitrate nitrogen reduction cathode 201. The PLC control system 601 is electrically connected to the DC regulated power supply 602, the ClO· concentration online monitoring probe 603, and the ammonia nitrogen concentration online monitoring probe 604.

[0081] The ultraviolet lamp 700 is fixedly installed on the top surface of each ammonia nitrogen catalytic oxidation anode 101 and nitrate nitrogen reduction cathode 201; and is electrically connected to the PLC control system 601.

[0082] A method of using an electrode system includes the following steps:

[0083] S1 Start-up: Wastewater is introduced into reactor 300, and the bottom mixer is turned on to ensure that the wastewater is in full contact with the ammonia nitrogen catalytic oxidation anode 101 of anode module 100 and the nitrate nitrogen reduction cathode 201 of cathode module 200.

[0084] S2 Electrocatalysis: When the DC regulated power supply 602 is turned on, the electrocatalytic state is entered. The catalytic oxidation coating 1012 on the outside of the ammonia nitrogen catalytic oxidation anode 101 and the cathode reduction coating 2012 on the outside of the nitrate nitrogen reduction cathode 201 come into contact with the ammonia nitrogen wastewater. ClO· is generated on the surface of the catalytic oxidation coating 1012 of the catalytic oxidation anode, so that the ammonia nitrogen in the wastewater is oxidized to nitrogen gas and removed. A small amount of nitrate nitrogen generated by peroxidation is reduced to nitrogen gas by the cathode reduction coating 2012 and removed, thereby realizing the removal of nitrogen from the wastewater.

[0085] S3 Capture: When the ClO· concentration online monitoring probe 603 detects that the ClO· concentration in the wastewater exceeds the upper limit, the signal is transmitted to the PLC control system 601. The PLC control system 601 shuts off the DC regulated power supply 602 and starts the circulating water pumps of the anode circulation module 400 and the cathode circulation module 500, allowing wastewater to flow into the ammonia nitrogen catalytic oxidation anode 101 and the nitrate nitrogen reduction cathode 201. When the water is full, the anode solenoid valve 401 and the cathode solenoid valve 504 are activated, causing the ammonia nitrogen catalytic oxidation anode 101 and the nitrate nitrogen reduction cathode 201 to enter a circulation state with water entering from the top and exiting from the bottom. Simultaneously, the flow difference between the circulating water pump and the outlet valve is controlled to ensure that each electrode is in a full water state and enters the ClO· capture state. In the ClO· capture state, the anode ClO· capture coating 1013 on the ammonia nitrogen catalytic oxidation anode 101 and the cathode ClO· capture coating 2023 on the nitrate nitrogen reduction cathode 201 come into contact with the wastewater. ClO· is captured by CeO2 on the anode ClO· capture coating 1013 and the cathode ClO· capture coating 2023, reducing the ClO· concentration in the wastewater and preventing excessive oxidation of ammonia nitrogen to generate nitrate nitrogen, thereby improving the selectivity of nitrogen gas, the electrocatalytic product of ammonia nitrogen wastewater.

[0086] S4 Reduction: When the ClO· concentration online monitoring probe 603 detects that the ClO· concentration in the wastewater is lower than the lower limit, the signal is transmitted to the PLC control system 601, and the ClO· capture coating enters the reduction state; in the reduction state of the ClO· capture coating, the PLC control system 601 shuts down the anode circulation pump 401 and the cathode circulation pump 502, and closes the anode solenoid valve 401 and the cathode solenoid valve 504 after a delay, draining the wastewater in the electrode cylinder; after draining, the top ultraviolet lamp 700 is turned on, so that the anode ClO· capture coating and the cathode ClO· capture coating can fully contact the ultraviolet light, release ClO·, and realize the reduction of the ClO· capture coating; after 30 minutes, the ultraviolet lamp 700 is turned off, the DC regulated power supply 602 is started, and the system returns to the electrocatalytic state.

[0087] S5: This cycle repeats until the online ammonia nitrogen concentration monitoring probe 604 on the cathode detects that the ammonia nitrogen concentration in the wastewater has reached the effluent standard, and transmits the signal to the PLC control system 601. The DC regulated power supply 602 is turned off, the bottom mixer is turned off, and the system enters the shutdown state.

[0088] Wastewater treatment experiment

[0089] 1. Leachate from a certain landfill

[0090] The water quality parameters of a landfill leachate system in operation before influent are shown in Table 1.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen are 2512.3, 41.2, and 2623.5 mg / L, respectively. Cl... - and SO4 2- The concentrations were 15045 and 8745 mg / L, respectively, and the TDS was 34265 mg / L; it was high-salt, high-ammonia-nitrogen wastewater.

[0091] This experiment used commercially available ruthenium-iridium-titanium electrodes as the control group and the electrode system of this invention as the experimental group to conduct electrocatalytic experiments on this landfill leachate. The experimental operating parameters are shown in Table 1.2. The current density was 300 mA / cm², and the water treatment capacity per unit anode plate area was 0.1 m³. 3 / m 2 The runtime is 9 hours.

[0092] The effluent quality is shown in Table 1.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen in the experimental group were 23.42, 50.42, and 70.34 mg / L, respectively, which were 189.03, 394.81, and 655.44 mg / L lower than those in the control group. The selectivity for nitrate nitrogen in the electrocatalytic product was 0.37% in the experimental group and 17.57% in the control group. This indicates that the present invention has a higher ammonia nitrogen and total nitrogen removal capacity than commercially available ruthenium-iridium-titanium electrodes, and significantly reduces nitrate nitrogen selectivity.

[0093] Table 1.1 Influent and Effluent Water Quality

[0094]

[0095]

[0096] Table 1.2 Operating Parameters

[0097]

[0098] 2. Wastewater from a pharmaceutical company

[0099] The water quality parameters of a pharmaceutical wastewater treatment plant in operation before influent are shown in Table 2.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen are 5423.54, 12.54, and 5514.23 mg / L, respectively. Cl... - and SO42- The concentrations were 20144 and 5642 mg / L, respectively, and the TDS was 50412.80 mg / L; it was high-salt, high-ammonia-nitrogen wastewater.

[0100] This experiment used commercially available ruthenium-iridium-titanium electrodes as the control group and the electrode system of this invention as the experimental group to conduct electrocatalytic experiments on this pharmaceutical wastewater. The experimental operating parameters are shown in Table 2.2. The current density was 300 mA / cm², and the water treatment capacity per unit anode plate area was 0.1 m³. 3 / m 2 The running time is 11 hours.

[0101] The effluent quality is shown in Table 2.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen in the experimental group were 1523.42, 150.78, and 1760.65 mg / L, respectively, which were 489.03, 494.76, and 964.91 mg / L lower than those in the control group. The selectivity for nitrate nitrogen in the electrocatalytic product was 3.54% in the experimental group and 18.56% in the control group. This indicates that the present invention has a higher ammonia nitrogen and total nitrogen removal capacity than commercially available ruthenium-iridium-titanium electrodes, and significantly reduces nitrate nitrogen selectivity.

[0102] Table 2.1 Influent and Effluent Water Quality

[0103]

[0104] Table 2.2 Operating Parameters

[0105]

[0106] 3. Textile dyeing wastewater

[0107] The water quality parameters of a textile dyeing and printing wastewater treatment plant in operation before influent are shown in Table 3.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen are 1423.54, 12.54, and 5514.23 mg / L, respectively. Cl... - and SO4 2- The concentrations were 9856 and 1546 mg / L, respectively, and the TDS was 22388.64 mg / L; it was high-salt, high-ammonia-nitrogen wastewater.

[0108] This experiment used commercially available ruthenium-iridium-titanium electrodes as the control group and the electrode system of this invention as the experimental group to conduct electrocatalytic experiments on this textile dyeing wastewater. The experimental operating parameters are shown in Table 3.2. The current density was 300 mA / cm², and the water treatment capacity per unit anode plate area was 0.1 m³. 3 / m 2 The running time is 5 hours.

[0109] The effluent quality is shown in Table 3.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen in the effluent of the experimental group were 25.46, 50.78, and 87.54 mg / L, respectively, which were 87.1, 136.87, and 138.02 mg / L lower than those in the control group. The selectivity of nitrate nitrogen, the electrocatalytic product, in the experimental group and the control group was 2.74% and 13.36%, respectively. This indicates that the present invention has a greater ammonia nitrogen and total nitrogen removal capacity than commercially available ruthenium-iridium-titanium electrodes, and significantly reduces nitrate nitrogen selectivity.

[0110] Table 3.1 Influent and Effluent Water Quality

[0111]

[0112] Table 3.2 Operating Parameters

[0113]

[0114] 4. Wastewater from pesticide synthesis

[0115] The water quality parameters of a pesticide synthesis wastewater currently in operation before influent are shown in Table 4.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen are 4785.12, 564.38, and 4963.45 mg / L, respectively. Cl... - and SO4 2- The concentrations were 25643 and 6545 mg / L, respectively, and the TDS was 62980 mg / L; it was high-salt, high-ammonia-nitrogen wastewater.

[0116] This experiment used commercially available ruthenium-iridium-titanium electrodes as the control group and the electrode system of this invention as the experimental group to conduct electrocatalytic experiments on this pesticide synthesis wastewater. The experimental operating parameters are shown in Table 4.2. The current density was 300 mA / cm², and the water treatment capacity per unit anode plate area was 0.1 m³. 3 / m 2 The running time is 13 hours.

[0117] The effluent quality is shown in Table 4.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen in the effluent of the experimental group were 258.94, 589.74, and 893.54 mg / L, respectively, which were 99.75, 567.13, and 754 mg / L lower than those in the control group. The selectivity of nitrate nitrogen, the electrocatalytic product, was 0.56% in the experimental group and 13.38% in the control group. This indicates that the present invention has a greater ammonia nitrogen and total nitrogen removal capacity than commercially available ruthenium-iridium-titanium electrodes, and significantly reduces nitrate nitrogen selectivity.

[0118] Table 4.1 Influent and Effluent Water Quality

[0119]

[0120] Table 4.2 Operating Parameters

[0121]

[0122] 5. Food processing wastewater

[0123] The water quality parameters of a food processing wastewater currently in operation before influent are shown in Table 5.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen are 475.12, 52.87, and 558.74 mg / L, respectively. - and SO4 2- The concentrations were 10258 and 3587 mg / L, respectively, and the TDS was 27010.46 mg / L; it was high-salt, high-ammonia-nitrogen wastewater.

[0124] This experiment used commercially available ruthenium-iridium-titanium electrodes as the control group and the electrode system of this invention as the experimental group to conduct electrocatalytic experiments on this food processing wastewater. The experimental operating parameters are shown in Table 4.2. The current density was 300 mA / cm², and the water treatment capacity per unit anode plate area was 0.1 m³. 3 / m 2 The running time is 2 hours.

[0125] The effluent quality is shown in Table 5.1. The concentrations of ammonia nitrogen, nitrate nitrogen, and total nitrogen in the effluent of the experimental group were 2.45, 66.23, and 41.42 mg / L, respectively, which were 33.39, 32.22, and 101.09 mg / L lower than those in the control group. The selectivity of nitrate nitrogen, the electrocatalytic product, in the experimental group and the control group was 2.83% and 10.38%, respectively. This indicates that the present invention has a greater ammonia nitrogen and total nitrogen removal capacity than commercially available ruthenium-iridium-titanium electrodes, and significantly reduces nitrate nitrogen selectivity.

[0126] Table 5.1 Influent and Effluent Water Quality

[0127]

[0128] Table 5.2 Operating Parameters

[0129]

[0130] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electrocatalytic electrode for ammonia nitrogen wastewater, characterized in that, The system includes an ammonia nitrogen catalytic oxidation anode and a nitrate nitrogen reduction cathode. The ammonia nitrogen catalytic oxidation anode comprises a Ti2 substrate. The Ti2 substrate has a hollow cylindrical structure with an open top and a closed bottom, and its outer surface is provided with a catalytic oxidation coating, while its inner surface is provided with an anode ClO·capture coating. The nitrate nitrogen reduction cathode comprises a porous biomass nanocarbon felt. The porous biomass nanocarbon felt has a hollow cylindrical structure with an open top and a closed bottom, and its outer surface is provided with a cathode reduction coating, while its inner surface is provided with a cathode ClO·capture coating. The catalytic oxidation coating is formed by spraying a catalytic oxidation coating onto the surface of a Ti2 substrate; the catalytic oxidation coating is a mixed solution obtained by mixing RuCl3, IrCl4, and ethylene glycol in a mass ratio of 1:1:

1. The anodic ClO·capture coating is formed by spraying anodic ClO·capture paint onto the surface of a Ti2 substrate; the anodic ClO·capture paint is a mixed solution obtained by mixing CeO2 and ethylene glycol at a mass ratio of 1.5:1; The cathode reduction coating is formed by applying cathode reduction coating material to the surface of porous biomass nano-carbon felt; the cathode reduction coating is a mixed solution obtained by mixing reduced nickel powder, reduced copper powder, and conductive adhesive in a mass ratio of 3:1:

9. The cathode ClO·capture coating is formed by applying the cathode ClO·capture coating to the surface of porous biomass nano carbon felt; the cathode ClO·capture coating is a mixed solution obtained by mixing CeO2 and conductive adhesive at a mass ratio of 35:

1.

2. The method for preparing the electrocatalytic electrode for ammonia nitrogen wastewater according to claim 1, characterized in that, Includes the following steps: Preparation of S1 ammonia nitrogen catalytic oxidation anode: (1) Catalytic oxidation coating spraying: The catalytic oxidation coating is sprayed onto one side of the cut and pretreated Ti2 substrate; (2) Anode ClO·capture coating spraying: Anode ClO·capture coating is sprayed on the other side of the Ti2 substrate in (1) to obtain the anode material; (3) Preparation of ammonia nitrogen catalytic oxidation anode: The anode material after coating drying and curing is rolled into a cylindrical structure with an open top, closed bottom, hollow interior, and catalytic oxidation coating facing outwards to obtain the ammonia nitrogen catalytic oxidation anode; Preparation of S2 nitrate nitrogen reduction cathode: (1) Preparation of porous biomass nano carbon felt: The biomass raw material is crushed and compacted to form a 2mm thick carbon felt, which is then carbonized at high temperature to obtain porous biomass nano carbon felt. (2) Preparation of cathodic reduction coating: The cathodic reduction coating solution is uniformly coated on one side of the porous biomass nano carbon felt obtained in (1); (3) Preparation of cathode ClO·capture coating: The cathode ClO·capture coating is uniformly coated on the other surface of the porous biomass nano carbon felt to obtain the cathode material; (4) Preparation of nitrate nitrogen reduction cathode: The cathode material after coating drying and curing is rolled into a cylindrical structure with an open top, a closed bottom, a hollow interior, and the cathode reduction coating facing outwards, to obtain the nitrate nitrogen reduction cathode.

3. The method for preparing the electrocatalytic electrode for ammonia nitrogen wastewater according to claim 2, characterized in that: The biomass in question is peanut shells.

4. The method for preparing the electrocatalytic electrode for ammonia nitrogen wastewater according to claim 2, characterized in that, The high-temperature carbonization is carried out in a nitrogen atmosphere at a temperature of 700°C for 5 hours.

5. An electrode system, characterized in that: Includes reactor, anode module, cathode module, anode circulation module, cathode circulation module, and control module; The anode module and cathode module are located inside the reactor; the anode module includes multiple ammonia nitrogen catalytic oxidation anodes as described in claim 1; the multiple ammonia nitrogen catalytic oxidation anodes are connected by an anode Ti2 rod; The cathode module includes multiple nitrate reduction cathodes as described in claim 1; the multiple nitrate reduction cathodes are connected by cathode Ti2 rods; The anode circulation module comprises multiple modules, each connected to a specific ammonia nitrogen catalytic oxidation anode. Each module includes an anode inlet pipe, an anode circulation pump, an anode outlet pipe, and an anode solenoid valve. One end of the anode inlet pipe is connected to the anode circulation pump, and the other end extends upwards and enters the ammonia nitrogen catalytic oxidation anode from the top. The anode circulation pump is connected to the anode inlet pipe. One end of the anode outlet pipe is connected to the bottom of the ammonia nitrogen catalytic oxidation anode, and the other end is located inside the reactor. The anode solenoid valve is connected to the anode outlet pipe. The cathode circulation module comprises multiple units, each connected to a nitrate nitrogen reduction cathode. Each unit includes a cathode inlet pipe, a cathode circulation pump, a cathode outlet pipe, and a cathode solenoid valve. One end of the anode inlet pipe is connected to the cathode circulation pump, and the other end extends upwards and enters the nitrate nitrogen reduction cathode from its top. The cathode circulation pump is connected to the cathode inlet pipe. One end of the cathode outlet pipe is connected to the bottom of the ammonia nitrogen catalytic oxidation cathode, and the other end is located inside the reactor. The cathode solenoid valve is connected to the cathode outlet pipe. The control module includes a PLC control system, a DC regulated power supply, an online ClO· concentration monitoring probe, an online ammonia nitrogen concentration monitoring probe, and an ultraviolet lamp. The DC regulated power supply is connected to one of the ammonia nitrogen catalytic oxidation anodes and one of the nitrate nitrogen reduction cathodes via wires. The online ClO· concentration monitoring probe is connected to the anode Ti2 rod. The online ammonia nitrogen concentration monitoring probe is connected to the cathode Ti2 rod. The ultraviolet lamp is fixedly mounted on the top surface of each ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode. The PLC control system is electrically connected to the DC regulated power supply, the online ClO· concentration monitoring probe, and the online ammonia nitrogen concentration monitoring probe. The ultraviolet lamps are fixedly mounted on the top surface of each ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode, and are electrically connected to the PLC control system.

6. The method of using the electrode system according to claim 5, characterized in that, Includes the following steps: S1 Start-up: Wastewater is introduced into the reactor and the bottom mixer is turned on to ensure that the wastewater is in full contact with the ammonia nitrogen catalytic oxidation anode of the anode module and the nitrate nitrogen reduction cathode of the cathode module. S2 Electrocatalysis: When the DC regulated power supply is turned on, the electrocatalytic state is entered. The catalytic oxidation coating on the outside of the ammonia nitrogen catalytic oxidation anode and the cathode reduction coating on the outside of the nitrate nitrogen reduction cathode come into contact with the ammonia nitrogen wastewater, thereby achieving nitrogen removal from the wastewater. S3 Capture: When the ClO· concentration online monitoring probe detects that the ClO· concentration in the wastewater exceeds the upper limit, the signal is transmitted to the PLC control system. The PLC control system shuts off the DC regulated power supply and starts the circulating water pumps of the anode and cathode circulation modules, allowing wastewater to flow into the ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode. When the water is full, the anode and cathode solenoid valves are activated, causing the ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode to enter a circulation state with water entering from the top and exiting from the bottom. At the same time, the flow difference between the circulating water pump and the outlet valve is controlled to ensure that each electrode is in a full water state and enters the ClO· capture state. In the ClO· capture state, the anode ClO· capture coating on the ammonia nitrogen catalytic oxidation anode and the cathode ClO· capture coating on the nitrate nitrogen reduction cathode come into contact with the wastewater, capturing ClO·, reducing the ClO· concentration in the wastewater, and preventing excessive oxidation of ammonia nitrogen to generate nitrate nitrogen. S4 Reduction: When the ClO· concentration online monitoring probe detects that the ClO· concentration in the wastewater is lower than the lower limit, the signal is transmitted to the PLC control system, and the ClO· capture coating enters the reduction state; in the reduction state of the ClO· capture coating, the PLC control system shuts down the anode circulation pump and the cathode circulation pump, and closes the anode solenoid valve and the cathode solenoid valve after a delay, draining the wastewater in the electrode cylinder; After draining, the top UV lamp is turned on to allow the anode ClO· capture coating and the cathode ClO· capture coating to fully contact the UV light, releasing ClO· and realizing the reduction of the ClO· capture coating; after 30 minutes, the UV lamp is turned off, the DC regulated power supply is started, and the system returns to the electrocatalytic state; S5: This cycle repeats until the online ammonia nitrogen concentration monitoring probe on the cathode detects that the ammonia nitrogen concentration in the wastewater has reached the effluent standard, and transmits the signal to the PLC control system. The DC regulated power supply is then turned off, the bottom mixer is turned off, and the system enters the shutdown state.

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