Ammonia-nitrogen wastewater electro-catalysis electrode, preparation method, electrode system and use method

Abstract

The invention relates to the technical field of sewage treatment, in particular to an ammonia nitrogen wastewater electro-catalysis electrode which comprises an ammonia nitrogen catalytic oxidation anode and a nitrate nitrogen reduction cathode. The ammonia nitrogen catalytic oxidation anode comprises a Ti2 base material; the Ti2 base material is of a cylindrical structure with an open top surface, a closed bottom surface and a hollow interior, a catalytic oxidation coating is arranged on the outer side surface of the Ti2 base material, and an anode ClO. Capture coating is arranged on the inner side surface of the Ti2 base material; the nitrate nitrogen reduction cathode comprises a porous biomass nano carbon felt; the multi-pore biomass nano carbon felt is of a cylindrical structure with an open top surface, a closed bottom surface and a hollow interior, a cathode reduction coating is arranged on the outer side surface of the multi-pore biomass nano carbon felt, and a cathode ClO. Capture coating is arranged on the inner side surface of the multi-pore biomass nano carbon felt. The invention also discloses a preparation method of the electrode, an electrode system comprising the electrode and a use method of the electrode system. According to the method, the selectivity of nitrate nitrogen can be reduced from the source, and the nitrogen element can be thoroughly removed from the wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to an ammonia nitrogen wastewater electrocatalytic electrode, a preparation method, an electrode system and a use method. Background Art

[0002] The treatment of high-salt and high-concentration ammonia nitrogen wastewater is a thorny issue in the field of sewage treatment. Its high salinity and high ammonia nitrogen concentration are both biologically toxic, and biological methods cannot treat such wastewater. The effect of ammonia stripping is affected by the ammonia nitrogen concentration and pH of the wastewater. When the ammonia nitrogen concentration is greater than 3000 mg / L and the pH is greater than 10, the effect of ammonia stripping is better. However, ammonia stripping also produces stripping waste gas that needs to be treated; the cost of adjusting the pH and stripping power is not low; and ammonia stripping is not effective in removing ammonia nitrogen below 1000 mg / L and cannot meet the effluent standard. High salt content means high conductivity, which can reduce the heat-generating side effect of electrocatalysis, thereby reducing the operating cost of electrocatalysis. In addition, electrocatalysis can adapt to a wide range of pollutant concentrations, and the effluent ammonia nitrogen can be close to 0 mg / L, and there is no upper limit to the ammonia nitrogen concentration that can be treated.

[0003] However, the electrocatalytic treatment of ammonia nitrogen wastewater also has significant disadvantages. The products of electrocatalytic oxidation of ammonia nitrogen include nitrogen, nitrite nitrogen, nitrate nitrogen, etc. The ideal result is to turn into non-toxic nitrogen and enter the atmosphere, but due to excessive oxidation, ammonia nitrogen is oxidized into nitrite nitrogen and nitrate nitrogen. Nitrite nitrogen is oxidized into nitrate nitrogen when it encounters air, and eventually becomes high-salt and high-nitrate nitrogen wastewater. Compared with high-salt and high-ammonia nitrogen wastewater, the electrocatalytic effect of high-salt and high-nitrate nitrogen wastewater is poor, and the removal of unit nitrate nitrogen requires more electricity consumption and longer operating time. Therefore, in the electrocatalytic treatment of ammonia nitrogen wastewater, product selectivity is crucial. In addition, the indirect oxidation of ClO· is the main mechanism for the oxidation and removal of ammonia nitrogen, but excessive ClO· will also lead to over-oxidation and high selectivity of nitrate nitrogen. Summary of the invention

[0004] The purpose of the present invention is to provide an ammonia nitrogen wastewater electrocatalytic electrode, a preparation method, an electrode system and a use method to solve the technical problems raised in the above background technology.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

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

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

[0008] Further, the anode ClO· capture coating is formed by spraying an anode ClO· capture coating material on the surface of the Ti2 substrate; the anode ClO· capture coating material is a mixed solution obtained by mixing CeO2 and ethylene glycol in a mass ratio of 1.5:1.

[0009] Further, the cathode reduction coating is formed by applying a cathode reduction coating material on the surface of the porous biomass nanocarbon 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] Further, the cathode ClO· capture coating is formed by applying a cathode ClO· capture coating material on the surface of the porous biomass nanocarbon felt; the cathode ClO· capture coating is a mixed solution obtained by mixing CeO2 and conductive adhesive in a mass ratio of 35:1.

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

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

[0013] (1) Spraying of the catalytic oxidation coating: Spraying a catalytic oxidation coating material on one side of the pre-cut and pre-treated Ti2 substrate;

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

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

[0016] S2 Preparation of the nitrate nitrogen reduction cathode:

[0017] (1) Preparation of porous-channel biomass nano-carbon felt: Crush and compact the biomass raw material to form a 2-mm-thick carbon felt, and perform high-temperature carbonization to obtain the porous-channel biomass nano-carbon felt;

[0018] (2) Preparation of cathode reduction coating: Uniformly apply the cathode reduction coating solution on one surface of the porous-channel biomass nano-carbon felt obtained in (1);

[0019] (3) Preparation of cathode ClO· capture coating: Uniformly apply the cathode ClO· capture coating on the other surface of the porous-channel biomass nano-carbon felt to obtain the cathode material;

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

[0021] Further, the biomass is peanut shell.

[0022] Further, the high-temperature carbonization is carried out in a nitrogen environment at a temperature of 700 °C and a carbonization time of 5 h.

[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 the cathode module are arranged in the reactor; the anode module includes ammonia nitrogen catalytic oxidation anodes among the plurality of electrodes; the plurality of ammonia nitrogen catalytic oxidation anodes are connected by an anode Ti2 rod;

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

[0026] There are a plurality of anode circulation modules, and the plurality of anode circulation modules are respectively connected to each ammonia nitrogen catalytic oxidation anode, including an anode water inlet pipe, an anode circulation pump, an anode water outlet pipe, and an anode solenoid valve; the anode water inlet pipe is connected to the anode circulation pump, and the other end extends upward and enters the interior of the ammonia nitrogen catalytic oxidation anode from the top of the ammonia nitrogen catalytic oxidation anode; the anode circulation pump is connected to the anode water inlet pipe; one end of the anode water outlet pipe is communicated with the bottom of the ammonia nitrogen catalytic oxidation anode, and the other end is located in the reactor; the anode solenoid valve is connected to the anode water outlet pipe;

[0027] There are multiple cathode circulation modules, and the multiple cathode circulation modules are respectively connected to each nitrate nitrogen reduction cathode, including a cathode inlet pipe, a cathode circulation pump, a cathode outlet pipe, and a cathode solenoid valve; the cathode inlet pipe is connected to the cathode circulation pump, and the other end extends upward and enters the interior of the nitrate nitrogen reduction cathode from the top of the nitrate nitrogen reduction cathode; the cathode circulation pump is connected to the cathode inlet pipe; one end of the cathode outlet pipe communicates with 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, a ClO· concentration on-line monitoring probe, an ammonia nitrogen concentration on-line monitoring probe, and an ultraviolet lamp; the DC regulated power supply is respectively connected to one of the ammonia nitrogen catalytic oxidation anodes and one of the nitrate nitrogen reduction cathodes through wires; the ClO· concentration on-line monitoring probe is connected to the anode Ti2 rod; the ammonia nitrogen concentration on-line monitoring probe is connected to the cathode Ti2 rod; the ultraviolet lamp is fixedly arranged 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 ClO· concentration on-line monitoring probe, and the ammonia nitrogen concentration on-line monitoring probe respectively;

[0029] The ultraviolet lamp is fixedly arranged on the top surface of each ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode; and is electrically connected to the PLC control system.

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

[0031] S1 Startup: Feed the wastewater into the reactor, start the bottom mixer, and make the wastewater fully contact with the ammonia nitrogen catalytic oxidation anode of the anode module and the nitrate nitrogen reduction cathode of the cathode module;

[0032] S2 Electro-catalysis: Turn on the DC regulated power supply to enter the electro-catalysis state. The catalytic oxidation coating outside the ammonia nitrogen catalytic oxidation anode and the cathode reduction coating outside the nitrate nitrogen reduction cathode come into contact with the ammonia nitrogen wastewater, thereby realizing the removal of nitrogen from the sewage;

[0033] S3 Capture: When the on-line monitoring probe of ClO· concentration 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 turns off the DC regulated power supply and starts the circulation water pumps of the anode circulation module and the cathode circulation module, and feeds the wastewater into the ammonia nitrogen catalytic oxidation anode and the nitrate nitrogen reduction cathode. When the water is full, the anode solenoid valve and the cathode solenoid valve are started, so that the ammonia nitrogen catalytic oxidation anode and the nitrate nitrogen reduction cathode enter the circulation state of upper part water inlet and bottom part water outlet. At the same time, the flow difference between the circulation water pump and the water outlet valve is controlled to make each electrode in a full water state and enter 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 contact with the wastewater to capture ClO·, reduce the ClO· concentration in the wastewater, and prevent the over-oxidation of ammonia nitrogen to form nitrate nitrogen.

[0034] S4 Reduction: When the on-line monitoring probe of ClO· concentration detects that the ClO· concentration in the wastewater is lower than the lower limit, the signal is transmitted to the PLC control system, and it enters the reduction state of the ClO· capture coating. In the reduction state of the ClO· capture coating, the PLC control system turns off the anode circulation pump and the cathode circulation pump, and delays turning off the anode solenoid valve and the cathode solenoid valve to drain the wastewater in the electrode cylinder. After draining, the top ultraviolet lamp is turned on to make the anode ClO· capture coating and the cathode ClO· capture coating fully contact with the ultraviolet light to release ClO·, realizing the reduction of the ClO· capture coating. After 30 minutes, the ultraviolet lamp is turned off and the DC regulated power supply is started, and the system resumes the electrocatalysis state.

[0035] S5: Repeat the cycle like this until the on-line monitoring probe of ammonia nitrogen concentration 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 is turned off and the bottom mixer is turned off, and the system enters the shutdown state. The beneficial effects of the present invention compared with the prior art are as follows:

[0036] The beneficial effects of the present invention compared with the prior art are as follows:

[0037] 1. In the electrodes of the present invention, the oxidation ability of the anode is controlled by the selection of the catalytic oxidation coating material to prevent the conversion of ammonia nitrogen to nitrate nitrogen due to the over-oxidation of the anode. By capturing the excessive ClO· by the ClO· capture coating, it is prevented that ammonia nitrogen is oxidized to nitrate nitrogen by excessive ClO·, reducing the selectivity of nitrate nitrogen at the source. The nitrate nitrogen generated by a small amount of over-oxidation is reduced to nitrogen gas by the cathode reduction coating, so as to realize the complete removal of nitrogen from the wastewater.

[0038] 2. The present invention prepares a porous biomass nano-carbon felt as the material of the cathode to increase the electron channels and functional groups, and the conductivity of the porous biomass nano-carbon felt can be improved by high-temperature carbonization, enhancing the treatment ability of the cathode plate.

[0039] 3. In the electrode system of the present invention, an anode module and a cathode module are respectively composed of multiple ammonia nitrogen catalytic oxidation anodes and multiple nitrate nitrogen reduction cathodes, and cooperate with a control module, a cathode circulation module and an anode circulation module to carry out electrocatalysis and ClO· capture, so as to achieve complete denitrification, significantly reduce the nitrate nitrogen selectivity. 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

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

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

[0047] Figure 8 is a schematic connection structure diagram 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 - Nitrate nitrogen reduction cathode; 2011 - Porous biomass nanocarbon felt; 2012 - Cathode reduction coating; 2023 - Cathode ClO· capture coating; 202 - Cathode Ti2 rod;

[0052] 300 - Reactor;

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

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

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

[0056] 700 - Ultraviolet lamp. Specific implementation manner

[0057] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following presents preferred embodiments with reference to the accompanying drawings and further elaborates on the present invention in detail. However, it should be noted that many details listed in the specification are only for enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

[0058] Embodiment 1

[0059] As Figures 1-4 shown, an ammonia nitrogen wastewater electrocatalytic electrode includes an ammonia nitrogen catalytic oxidation anode 101 and a nitrate nitrogen reduction cathode 201; the ammonia nitrogen catalytic oxidation anode 101 includes a Ti2 substrate; the Ti2 substrate is a cylindrical structure with an open top, a closed bottom and a hollow interior, and a catalytic oxidation coating 1012 is provided on its outer surface and an anode ClO· capture coating 1013 is provided on its inner surface; the nitrate nitrogen reduction cathode 201 includes a porous biomass nanocarbon felt 2011; the porous biomass nanocarbon felt 2011 is a cylindrical structure with an open top, a closed bottom and a hollow interior, and a cathode reduction coating 2012 is provided on its outer surface and a cathode ClO· capture coating 2023 is provided on its inner surface.

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

[0061] The anode ClO· capture coating 1013 is formed by spraying an anode ClO· capture coating material on the surface of the Ti2 substrate; the anode ClO· capture coating material is a mixed solution obtained by mixing CeO2 and ethylene glycol in a mass ratio of 1.5:1.

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

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

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

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

[0066] (1) Spraying of the catalytic oxidation coating 1012: After the Ti2 substrate 1011 is cut and pretreated, it forms an unfolded shape of a cylindrical structure with an open top, a closed bottom, and a hollow interior, with a thickness of 1 mm. Then, one side of the Ti2 substrate 1011 is sprayed with the catalytic oxidation coating material; the layer thickness is controlled at 0.8 ± 0.1 μm and dried in a tubular furnace at 120 °C for 30 min; the cycle is 3 times; where the spraying medium is nitrogen at 0.4 Mpa, the flow rate is 0.5 mL / min; the spraying distance is 12 cm; the substrate temperature is 90 ± 5 °C; the environmental relative humidity and temperature are 20% and 25 °C respectively;

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

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

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

[0070] (1) Preparation of porous-channel biomass nano-carbon felt 2011: Crush and compact the peanut shell biomass raw material to form a carbon felt with a thickness of 2 mm, carbonize it at a temperature of 700 °C for 5 h in a nitrogen environment to obtain the porous-channel biomass nano-carbon felt 2011, and cut it into an unfolded shape of a cylindrical structure with an open top surface, a closed bottom surface, and a hollow interior;

[0071] (2) Preparation of cathode reduction coating 2012: Uniformly apply the cathode reduction coating 2012 solution on one side surface of the porous-channel biomass nano-carbon felt 2011 obtained in (1);

[0072] (3) Preparation of cathode ClO· capture coating 2023: Uniformly apply the cathode ClO· capture coating on the other surface of the porous-channel biomass nano-carbon felt 2011 to obtain the cathode material;

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

[0074] As Figures 5-8 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 the cathode module 200 are arranged in 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 by an anode Ti2 rod 102;

[0077] The cathode module 200 includes a plurality of nitrate nitrogen reduction cathodes 201; the plurality of nitrate nitrogen reduction cathodes 201 are connected by a cathode Ti2 rod 202;

[0078] A plurality of the anode circulation modules 400 are provided, and the plurality of anode circulation modules 400 are respectively connected to each ammonia nitrogen catalytic oxidation anode 101, including an anode water inlet pipe 401, an anode circulation pump 401, an anode water outlet pipe 401, and an anode solenoid valve 401; one end of the anode water inlet pipe 401 is connected to the anode circulation pump 401, and the other end extends upward and enters the inside of the ammonia nitrogen catalytic oxidation anode 101 from the top of the ammonia nitrogen catalytic oxidation anode 101; the anode circulation pump 401 is connected to the anode water inlet pipe 401; one end of the anode water outlet pipe 401 communicates with the bottom of the ammonia nitrogen catalytic oxidation anode 101, and the other end is located in the reactor 300; the anode solenoid valve 401 is connected to the anode water outlet pipe 401;

[0079] A plurality of the cathode circulation modules 500 are provided, and the plurality of cathode circulation modules 500 are respectively connected to each nitrate nitrogen reduction cathode 201, including a cathode water inlet pipe 501, a cathode circulation pump 502, a cathode water outlet pipe 503, and a cathode solenoid valve 504; one end of the cathode water inlet pipe 501 is connected to the cathode circulation pump 502, and the other end extends upward and enters the inside of the nitrate nitrogen reduction cathode 201 from the top of the nitrate nitrogen reduction cathode 201; the cathode circulation pump 502 is connected to the cathode water inlet pipe 501; one end of the cathode water outlet pipe 503 communicates with the bottom of the nitrate nitrogen reduction cathode 201, and the other end is located in the reactor 300; the cathode solenoid valve 504 is connected to the cathode water outlet pipe 503;

[0080] The control module 600 includes a PLC control system 601, a DC regulated power supply 602, a ClO· concentration on-line monitoring probe 603, and an ammonia nitrogen concentration on-line monitoring probe 604; the DC regulated power supply 602 is respectively connected to one ammonia nitrogen catalytic oxidation anode 101 and one nitrate nitrogen reduction cathode 201 through wires; the ClO· concentration on-line monitoring probe 603 is connected to the anode Ti2 rod 102; the ammonia nitrogen concentration on-line monitoring probe 604 is connected to the cathode Ti2 rod 202; the ultraviolet lamp 700 is fixedly arranged 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 on-line monitoring probe 603, and the ammonia nitrogen concentration on-line monitoring probe 604;

[0081] The ultraviolet lamp 700 is fixedly arranged 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 for using an electrode system includes the following steps:

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

[0084] S2 Electro-catalysis: Turn on the DC regulated power supply 602 to enter the electro-catalysis state. The catalytic oxidation coating 1012 outside the ammonia nitrogen catalytic oxidation anode 101 and the cathode reduction coating 2012 outside 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, oxidizing the ammonia nitrogen in the wastewater to nitrogen for removal. A small amount of nitrate nitrogen generated by peroxidation is reduced to nitrogen by the cathode reduction coating 2012, thus achieving the removal of nitrogen from the sewage.

[0085] S3 Capture: When the on-line monitoring probe 603 for ClO· concentration 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 turns off the DC regulated power supply 602 and starts the circulation pumps of the anode circulation module 400 and the cathode circulation module 500, feeding the wastewater into the ammonia nitrogen catalytic oxidation anode 101 and the nitrate nitrogen reduction cathode 201. When full, the anode solenoid valve 401 and the cathode solenoid valve 504 are activated, putting the ammonia nitrogen catalytic oxidation anode 101 and the nitrate nitrogen reduction cathode 201 into a circulating state of upper inlet and bottom outlet. At the same time, control the flow difference between the circulation pump and the outlet valve to keep each electrode in a full-water state and enter 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. CeO2 on the anode ClO· capture coating 1013 and the cathode ClO· capture coating 2023 captures ClO·, reducing the ClO· concentration in the wastewater and preventing the over-oxidation of ammonia nitrogen to nitrate nitrogen, thereby improving the selectivity of nitrogen, the electro-catalytic product of ammonia nitrogen wastewater.

[0086] S4 Reduction: When the on-line monitoring probe 603 for ClO· concentration detects that the ClO· concentration in the wastewater is below the lower limit, the signal is transmitted to the PLC control system 601 to enter the reduction state of the ClO· capture coating. In the reduction state of the ClO· capture coating, the PLC control system 601 turns off the anode circulation pump 401 and the cathode circulation pump 502, and delays turning off the anode solenoid valve 401 and the cathode solenoid valve 504 to drain the wastewater in the electrode cylinder. After draining, the top ultraviolet lamp 700 is turned on to ensure that the anode ClO· capture coating and the cathode ClO· capture coating are fully exposed to ultraviolet light to release ClO· and achieve the reduction of the ClO· capture coating. After 30 minutes, the ultraviolet lamp 700 is turned off and the DC regulated power supply 602 is started, and the system resumes the electro-catalysis state.

[0087] S5: This cycle repeats until the online monitoring probe 604 for ammonia nitrogen concentration 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 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 garbage

[0090] The water quality parameters of a certain garbage leachate before water inflow 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. - and SO4 2- The concentrations are 15045 and 8745 mg / L respectively, and the TDS is 34265 mg / L; it is high-salt and high-ammonia nitrogen wastewater.

[0091] In this experiment, commercially available ruthenium-iridium-titanium electrodes were used as the control group, and the electrode system of the present invention was used as the experimental group to conduct an electrocatalytic test on the landfill leachate. The test operation parameters are shown in Table 1.2. The current density is 300 mA / cm, and the water volume treated per unit anode plate area is 0.1 m 3 / m 2 , running time is 9h.

[0092] The effluent quality is shown in Table 1.1. The effluent ammonia nitrogen, nitrate nitrogen and total nitrogen concentrations of the test 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 of the control group, respectively; the selectivity of nitrate nitrogen in the electrocatalytic product of the test group and the control group was 0.37% and 17.57%, respectively. This shows that the present invention has a better ammonia nitrogen and total nitrogen removal capacity than the ruthenium iridium titanium electrode purchased on the market, and significantly reduces the selectivity of nitrate nitrogen.

[0093] Table 1.1 Inlet and outlet water quality

[0094]

[0095]

[0096] Table 1.2 Operating parameters

[0097]

[0098] 2. A pharmaceutical wastewater

[0099] The water quality parameters of a pharmaceutical wastewater in operation before water inflow 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. - and SO42- The concentrations are 20144 and 5642 mg / L respectively, and the TDS is 50412.80 mg / L; it is high-salt and high-ammonia-nitrogen wastewater.

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

[0101] The effluent water quality is shown in Table 2.1. The ammonia-nitrogen, nitrate-nitrogen and total-nitrogen concentrations in the effluent of the experimental group are 1523.42, 150.78 and 1760.65 mg / L respectively, which are 489.03, 494.76 and 964.91 mg / L lower than those of the control group respectively; the nitrate-nitrogen selectivities of the electrocatalytic products of the experimental group and the control group are 3.54% and 18.56% respectively. It shows that the present invention has better ammonia-nitrogen and total-nitrogen removal capabilities compared with the commercially available ruthenium-iridium-titanium electrode, and significantly reduces the nitrate-nitrogen selectivity.

[0102] Table 2.1 Influent and effluent water quality

[0103]

[0104] Table 2.2 Operating parameters

[0105]

[0106] 3 A certain textile printing and dyeing wastewater

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

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

[0109] The effluent water quality is shown in Table 3.1. The concentrations of ammonia nitrogen, nitrate nitrogen and total nitrogen in the effluent of the experimental group are 25.46, 50.78, and 87.54 mg / L respectively, which are 87.1, 136.87, and 138.02 mg / L lower than those of the control group; the selectivities of nitrate nitrogen in the electrocatalytic products of the experimental group and the control group are 2.74% and 13.36% respectively. It shows that the present invention has stronger ammonia nitrogen and total nitrogen removal capabilities compared with the ruthenium-iridium-titanium electrode purchased on the market, and significantly reduces the selectivity of nitrate nitrogen.

[0110] Table 3.1 Influent and effluent water quality

[0111]

[0112] Table 3.2 Operating parameters

[0113]

[0114] 4 A certain pesticide synthesis wastewater

[0115] For a certain pesticide synthesis wastewater in operation, the water quality parameters 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, and the concentrations of Cl - and SO4 2- are 25643 and 6545 mg / L respectively, and the TDS is 62980 mg / L; it is a high-salt and high-ammonia-nitrogen wastewater.

[0116] In this experiment, the ruthenium-iridium-titanium electrode purchased on the market was used as the control group, and the electrode system of the present invention was used 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 is 300 mA / cm, the water treatment volume per unit anode plate area is 0.1 m 3 / m 2 , and the operating time is 13 h.

[0117] The effluent water quality is shown in Table 4.1. The concentrations of ammonia nitrogen, nitrate nitrogen and total nitrogen in the effluent of the experimental group are 258.94, 589.74, and 893.54 mg / L respectively, which are 99.75, 567.13, and 754 mg / L lower than those of the control group; the selectivities of nitrate nitrogen in the electrocatalytic products of the experimental group and the control group are 0.56% and 13.38% respectively. It shows that the present invention has stronger ammonia nitrogen and total nitrogen removal capabilities compared with the ruthenium-iridium-titanium electrode purchased on the market, and significantly reduces the selectivity of nitrate nitrogen.

[0118] Table 4.1 Influent and effluent water quality

[0119]

[0120] Table 4.2 Operating parameters

[0121]

[0122] 5 Certain food processing wastewater

[0123] For the running certain food processing wastewater, the water quality parameters before water inlet are shown in Table 5.1. The concentrations of ammonia nitrogen, nitrate nitrogen and total nitrogen are 475.12, 52.87, 558.74 mg / L respectively, and the concentrations of Cl - and SO4 2- are 10258, 3587 mg / L respectively, and the TDS is 27010.46 mg / L; it is high-salt and high-ammonia-nitrogen wastewater.

[0124] In this experiment, the ruthenium-iridium-titanium electrode purchased on the market is used as the control group, and the electrode system of the present invention is used as the experimental group to conduct an electrocatalytic experiment on this food processing wastewater. The experimental operation parameters are shown in Table 4.2. The current density is 300 mA / cm, the water treatment volume per unit anode plate area is 0.1 m 3 / m 2 , and the running time is 2 h.

[0125] The effluent water quality is shown in Table 5.1. The concentrations of ammonia nitrogen, nitrate nitrogen and total nitrogen in the effluent of the experimental group are 2.45, 66.23, 41.42 mg / L respectively, which are 33.39, 32.22, 101.09 mg / L lower than those of the control group respectively; the selectivities of electrocatalytic product nitrate nitrogen in the experimental group and the control group are 2.83% and 10.38% respectively. It shows that the present invention has better ammonia nitrogen and total nitrogen removal capabilities compared with the ruthenium-iridium-titanium electrode purchased on the market, and significantly reduces the selectivity of nitrate nitrogen.

[0126] Table 5.1 Influent and effluent water quality

[0127]

[0128] Table 5.2 Operation parameters

[0129]

[0130] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. An electrocatalytic electrode for ammonia nitrogen wastewater, characterized in that, It includes an ammonia nitrogen catalytic oxidation anode and a nitrate nitrogen reduction cathode; the ammonia nitrogen catalytic oxidation anode includes a Ti2 substrate; the Ti2 substrate is a cylindrical structure with an open top, a closed bottom, and a hollow interior. Its outer surface is provided with a catalytic oxidation coating, and its inner surface is provided with an anode ClO· capture coating; the nitrate nitrogen reduction cathode includes a porous biomass nanocarbon felt; the porous biomass nanocarbon felt is a cylindrical structure with an open top, a closed bottom, and a hollow interior. Its outer surface is provided with a cathode reduction coating, and its inner surface is provided with a cathode ClO· capture coating.

2. The electrocatalytic electrode for ammonia nitrogen wastewater according to claim 1, wherein: The catalytic oxidation coating is formed by spraying a catalytic oxidation coating material on the surface of the Ti2 substrate; the catalytic oxidation coating material is a mixed solution obtained by mixing RuCl3, IrCl4, and ethylene glycol in a mass ratio of 1:1:

1.

3. The electrocatalytic electrode for ammonia nitrogen wastewater according to claim 2, wherein: The anode ClO· capture coating is formed by spraying an anode ClO· capture coating material on the surface of the Ti2 substrate; the anode ClO· capture coating material is a mixed solution obtained by mixing CeO2 and ethylene glycol in a mass ratio of 1.5:

1.

4. The electrocatalytic electrode for ammonia nitrogen wastewater according to claim 3, characterized in that: The cathode reduction coating is formed by applying a cathode reduction coating material on the surface of the porous biomass nanocarbon 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.

5. The electrocatalytic electrode for ammonia nitrogen wastewater according to claim 4, wherein: The cathode ClO· capture coating is formed by applying a cathode ClO· capture coating material on the surface of the porous biomass nanocarbon felt; the cathode ClO· capture coating is a mixed solution obtained by mixing CeO2 and conductive adhesive in a mass ratio of 35:

1.

6. The preparation method of the electrocatalytic electrode for ammonia nitrogen wastewater according to claim 5, characterized in that, It includes the following steps: S1 Preparation of the ammonia nitrogen catalytic oxidation anode: (1) Spraying of the catalytic oxidation coating: Spray the catalytic oxidation coating material on one side of the cut and pretreated Ti2 substrate. (2) Spraying of the anode ClO· capture coating: Spray the anode ClO· capture coating material on the other side of the Ti2 substrate in (1) to obtain the anode material. (3) Preparation of the ammonia nitrogen catalytic oxidation anode: Roll the anode material after coating drying and curing into a cylindrical structure with an open top, a closed bottom, a hollow interior, and the catalytic oxidation coating facing outwards to obtain the ammonia nitrogen catalytic oxidation anode. S2 Preparation of the nitrate nitrogen reduction cathode: (1) Preparation of the porous biomass nanocarbon felt: Crush and compact the biomass raw material to form a 2 mm thick carbon felt, and perform high-temperature carbonization to obtain the porous biomass nanocarbon felt. (2) Preparation of the cathode reduction coating: Uniformly apply the cathode reduction coating solution on one side surface of the porous biomass nanocarbon felt obtained in (1). (3) Preparation of the cathode ClO· capture coating: Uniformly apply the cathode ClO· capture coating material on the other surface of the porous biomass nanocarbon felt to obtain the cathode material. (4) Preparation of the nitrate nitrogen reduction cathode: Roll the cathode material after coating drying and curing 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.

7. The preparation method of the electrocatalytic electrode for ammonia nitrogen wastewater according to claim 6, characterized in that: The biomass is peanut shells.

8. The preparation method of the electrocatalytic electrode for ammonia nitrogen wastewater according to claim 6, characterized in that, The high-temperature carbonization is carried out in a nitrogen environment at a temperature of 700 °C and a carbonization time of 5 h.

9. An electrode system, characterized in that: It includes a reactor, an anode module, a cathode module, an anode circulation module, a cathode circulation module, and a control module; The anode module and the cathode module are arranged in the reactor; the anode module includes a plurality of ammonia nitrogen catalytic oxidation anodes in the electrodes as described in claim 1; the plurality of ammonia nitrogen catalytic oxidation anodes are connected by an anode Ti2 rod; The cathode module includes a plurality of nitrate nitrogen reduction cathodes in the electrodes as described in claim 1; the plurality of nitrate nitrogen reduction cathodes are connected by a cathode Ti2 rod; A plurality of anode circulation modules are provided, and the plurality of anode circulation modules are respectively connected to each ammonia nitrogen catalytic oxidation anode, and include 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 upward and enters the inside of the ammonia nitrogen catalytic oxidation anode from the top of the ammonia nitrogen catalytic oxidation anode; the anode circulation pump is connected to the anode inlet pipe; one end of the anode outlet pipe communicates with the bottom of the ammonia nitrogen catalytic oxidation anode, and the other end is located in the reactor; the anode solenoid valve is connected to the anode outlet pipe; A plurality of cathode circulation modules are provided, and the plurality of cathode circulation modules are respectively connected to each nitrate nitrogen reduction cathode, and include 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 upward and enters the inside of the nitrate nitrogen reduction cathode from the top of the nitrate nitrogen reduction cathode; the cathode circulation pump is connected to the cathode inlet pipe; one end of the cathode outlet pipe communicates with the bottom of the ammonia nitrogen catalytic oxidation cathode, and the other end is located in 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, a ClO· concentration on-line monitoring probe, an ammonia nitrogen concentration on-line monitoring probe, and an ultraviolet lamp; the DC regulated power supply is respectively connected to one ammonia nitrogen catalytic oxidation anode and one nitrate nitrogen reduction cathode through wires; the ClO· concentration on-line monitoring probe is connected to the anode Ti2 rod; the ammonia nitrogen concentration on-line monitoring probe is connected to the cathode Ti2 rod; the ultraviolet lamp is fixedly arranged 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 ClO· concentration on-line monitoring probe, and the ammonia nitrogen concentration on-line monitoring probe respectively; The ultraviolet lamp is fixedly arranged on the top surface of each ammonia nitrogen catalytic oxidation anode and nitrate nitrogen reduction cathode; and is electrically connected to the PLC control system.

10. The method of using the electrode system according to claim 9, wherein, It includes the following steps: S1 Start-up: The wastewater is introduced into the reactor, and the bottom mixer is turned on to make the wastewater fully contact with the ammonia nitrogen catalytic oxidation anode of the anode module and the nitrate nitrogen reduction cathode of the cathode module; S2 Electro-catalysis: The DC regulated power supply is turned on to enter the electro-catalysis state. 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, so as to realize the removal of nitrogen from the sewage; S3 Capture: When the on-line monitoring probe for the concentration of ClO· detects that the concentration of ClO· in the wastewater exceeds the upper limit, the signal is transmitted to the PLC control system. The PLC control system shuts down the DC regulated power supply and starts the circulation pumps of the anode circulation module and the cathode circulation module, and feeds the wastewater into the ammonia nitrogen catalytic oxidation anode and the nitrate nitrogen reduction cathode. When the water is full, the anode solenoid valve and the cathode solenoid valve are started, so that the ammonia nitrogen catalytic oxidation anode and the nitrate nitrogen reduction cathode enter the circulation state of upper part water inlet and bottom part water outlet. At the same time, the flow difference between the circulation pump and the outlet valve is controlled to make each electrode in a full water state and enter 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 contact with the wastewater to capture ClO·, reduce the ClO· concentration in the wastewater, and prevent the over-oxidation of ammonia nitrogen to generate nitrate nitrogen. S4 Reduction: When the on-line monitoring probe for the concentration of ClO· detects that the concentration of ClO· in the wastewater is lower than the lower limit, the signal is transmitted to the PLC control system and enters the reduction state of the ClO· capture coating. 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 delays to shut down the anode solenoid valve and the cathode solenoid valve, and drains the wastewater in the electrode cylinder. After draining, the ultraviolet lamp at the top is turned on to make the anode ClO· capture coating and the cathode ClO· capture coating fully contact with ultraviolet light to release ClO· and realize the reduction of the ClO· capture coating. After 30 minutes, the ultraviolet lamp is turned off and the DC regulated power supply is started, and the system resumes the electrocatalysis state. S5: Repeat the cycle like this until the on-line monitoring probe for the ammonia nitrogen concentration 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 is turned off and the bottom mixer is turned off, and the system enters the shutdown state.

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