Preparation Method of Boron Carbide Particles and Its Three-Dimensional Electrochemical Device

Abstract

An embodiment of the present invention provides a preparation method of a boron carbide particle electrode and its three-dimensional electrochemical device. The preparation method of the boron carbide filler includes the following steps: stirring and mixing boron carbide powder, carbon black powder, a catalyst, and a granulation aid to obtain a premix; granulating the premix to agglomerate the granulation aid with the boron carbide powder, the catalyst, and the carbon black powder to obtain premix particles; drying the premix particles; and calcining the dried premix particles at a high temperature to obtain boron carbide particles. The preparation method of the boron carbide particle electrode of the present invention is simple, can provide more redox sites for electrochemistry to react, and can be applied to the synchronous and efficient removal of organic matter and nitrate in high-salt brine.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection technologies, and particularly relates to a preparation method of boron carbide particles and a three-dimensional electrochemical device thereof. Background Art

[0002] At present, with the country's control over the salt content of industrial wastewater discharged by industrial enterprises, further promoting the process of zero discharge of industrial wastewater, the high contents of organic matter and nitrate in the membrane concentrated water in the zero-discharge process have seriously affected the quality of salt production. Affected by the high concentration of salt in the concentrated water, the traditional Fenton process has a very low efficiency in removing organic matter, and the microorganisms in the nitrate biochemical removal process can hardly bear it. As a reducing agent, hydroxylamine hydrochloride can promote the iron cycle in Fenton, improve the yield of hydroxyl radicals, and improve the treatment efficiency of Fenton. However, there are problems such as high reagent costs and the generation of additional nitrates. Electrochemical technology shows good effects on the removal of organic matter and the reduction of nitrate in the treatment of high-salt wastewater, but the synchronous removal efficiency of organic matter and nitrate in wastewater is low. Therefore, how to achieve the simultaneous and efficient removal of organic matter and nitrate is the key to the application of electrochemical technology in the treatment of industrial wastewater concentrated water.

[0003] Currently, commonly used three-dimensional particle electrodes such as activated carbon, copper foam, and nickel foam have disadvantages such as easy loss and heavy metal dissolution. Nanoscale boron carbide has good stability, conductivity, and reducibility, and can promote the iron cycle in Fenton oxidation and efficiently reduce nitrate nitrogen to nitrogen or ammonia nitrogen. Nanoscale non-precious metal oxide catalysts such as titanium dioxide have low costs and strong catalytic activities, and can significantly improve the catalytic activity of boron carbide. Therefore, the addition of non-precious metal oxide catalysts and nanoscale boron carbide to prepare particle electrodes will form many micro-electrolytic cells in the electrolytic reactor, improve the mass transfer efficiency, effectively improve the degradation rate of pollutants, and at the same time reduce the dosage of hydroxylamine hydrochloride and promote the reaction of hydroxylamine hydrochloride to generate nitrogen. Currently, commercially available products of nanoscale boron carbide and non-precious metal oxide catalysts are in powder form and are easy to lose when used as particle electrodes, so their use is greatly restricted. Summary of the Invention

[0004] Aiming at the defects of the prior art, the present invention provides a preparation method of boron carbide particles and a three-dimensional electrochemical device thereof. The prepared boron carbide particles have the characteristics of high reduction activity, high stability, and conductivity; when the three-dimensional electrochemical device uses boron carbide particles as electrodes, it has electro-Fenton and electro-reduction functions, and can achieve the purpose of efficiently and stably removing organic matter and nitrogen in concentrated water.

[0005] In a first aspect, the present application provides a preparation method of boron carbide particles, including the steps of:

[0006] Mix boron carbide powder, carbon black powder, a catalyst, and a granulation aid by stirring to obtain a premix;

[0007] Granulate the premix to agglomerate the granulation aid with boron carbide powder, catalyst and carbon black powder to obtain premix particles;

[0008] Dry the premix particles;

[0009] Calcine the dried premix particles at high temperature to obtain boron carbide particles.

[0010] In a preferred embodiment, the granulation aid includes a surfactant, a pore-forming agent and a binder; wherein, by mass, the premix includes 90-100 parts of boron carbide powder, 2-4 parts of carbon black powder, 1-2.5 parts of surfactant, 5-10 parts of catalyst, 2-5 parts of pore-forming agent and 0.5-1 part of binder, and the boron carbide powder is nanoscale with an average particle size of 50 nm; the average particle size of the carbon black powder is 20 nm.

[0011] In a preferred embodiment, the catalyst includes at least one of nano titanium oxide (TiO2), nano tin oxide (SnO2), nano zirconium oxide (ZrO2), the particle size of the catalyst is 10-50 nm, the surfactant includes one or more of stearic acid, ammonium polyacrylate and tetramethylammonium hydroxide, the pore-forming agent includes polyethylene glycol, and the binder includes a combination of high-density polyethylene and ethylene-vinyl acetate copolymer, and the mass percentage of high-density polyethylene and ethylene-vinyl acetate is 1:1.

[0012] In a preferred embodiment, the time for stirring and mixing the boron carbide powder, catalyst, carbon black powder and granulation aid is 10-20 hours;

[0013] The step of granulating the premix includes:

[0014] Stir the premix at a rate of 20-40 r / min for 35-45 min;

[0015] Increase the rotation speed to 40-50 r / min and continue stirring for 1-2 h;

[0016] Wherein, the elevation angle of the turntable of the granulator during stirring is 30-75°;

[0017] The step of drying the premix includes:

[0018] Dry the premix at a temperature of 80-110 °C for 4-6 h;

[0019] The step of calcining the dried premix particles at high temperature includes:

[0020] Calcine at a high temperature of 500-600 °C for 4-8 h under nitrogen protection.

[0021] Second aspect, the present invention proposes a three-dimensional electrochemical device, including boron carbide particles prepared by the preparation method of boron carbide particles described in the above-mentioned embodiments, and the boron carbide particles are filled in the three-dimensional electrochemical device as a three-dimensional electrode.

[0022] In a preferred embodiment, the three-dimensional electrochemical device further includes:

[0023] An electrolytic cell, the electrolytic cell includes a water inlet and a water outlet; the electrolytic cell is a bottom-in and top-out tank structure;

[0024] An electrode unit, the electrode unit is arranged in the electrolytic cell, the electrode unit includes an anode plate, a cathode plate and the boron carbide particles, the anode plate and the cathode plate are alternately arranged at intervals, and the anode plate and the cathode plate are parallel to the water flow direction in the electrolytic cell, and the boron carbide particles are filled between the anode plate and the adjacent cathode plate as a three-dimensional electrode to form a three-dimensional electrode reaction chamber; wherein, both the anode plate and the cathode plate are connected to a power supply;

[0025] A chemical dosing unit, the chemical dosing unit is communicated with the electrolytic cell, and the chemical dosing unit is used for dosing Fenton reagent and controlling the pH value in the electrolytic cell.

[0026] In a preferred embodiment, the cross-section at the bottom of the electrolytic cell gradually shrinks to form a sludge discharge hopper with a funnel-shaped sludge discharge area, and a sludge discharge port is opened below the sludge discharge hopper.

[0027] In a preferred embodiment, an aeration pipeline connected to an external aerator is arranged in the electrolytic cell, a plurality of aeration branch pipes are arranged on the aeration pipeline, and the aeration branch pipes are communicated with the bottom of the three-dimensional electrode reaction chamber in the electrode unit, and the aeration branch pipes are used for supplying oxygen to the three-dimensional electrode reaction chamber.

[0028] In a preferred embodiment, a detachable insulating basket with pores is arranged between the adjacent anode plate and the cathode plate, the pore diameter of the insulating basket is smaller than the diameter of the boron carbide particles, and a plurality of insulating partition plates are arranged in the insulating basket to divide the insulating basket into multiple layers, and each layer is filled with boron carbide particles as an electrode;

[0029] The anode plate includes one or more of a mesh DSA, BDD and an iron plate electrode, and the cathode plate includes one or more of graphite, graphite felt, a titanium plate and a copper-based material; wherein, when the anode plate is an iron electrode, the anode plate can be used as an induction electrode.

[0030] In a preferred embodiment, the chemical dosing unit includes a ferrous sulfate storage tank, a hydrogen peroxide storage tank, a sulfuric acid storage tank, a hydroxylamine hydrochloride storage tank, a dosing pump, and an on-line pH meter; the ferrous sulfate storage tank, the hydrogen peroxide storage tank, the sulfuric acid storage tank, and the hydroxylamine hydrochloride storage tank are connected to the electrolytic cell through dosing pipes, the dosing pump is used to control the chemical dosing amounts of the ferrous sulfate storage tank, the hydrogen peroxide storage tank, the sulfuric acid storage tank, and the hydroxylamine hydrochloride storage tank, and the on-line pH meter is used to control the pH value in the electrolytic cell.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: the boron carbide particles prepared by the present invention have the characteristics of high reduction activity, high stability, and conductivity, and in a three-dimensional electrochemical device, through the three-dimensional electrode composed of the anode and cathode plates and the prepared boron carbide particles filled therebetween, and the addition of hydroxylamine hydrochloride, it can effectively promote the iron cycle in electrochemical Fenton oxidation and the conversion of nitrate into nitrogen, inhibit the reaction of hydroxylamine hydrochloride to generate nitrate, achieve the purpose of synchronously and efficiently removing organic matter and nitrogen in the concentrated water, and at the same time, the good conductivity of the prepared boron carbide particles can also effectively improve the current efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In the drawings, unless otherwise specified, the same reference numerals throughout the several views denote the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in accordance with the present invention and should not be regarded as limiting the scope of the present invention.

[0033] Figure 1 It is a schematic structural diagram of a three-dimensional electrochemical device of a boron carbide particle electrode according to a preferred embodiment of the present invention.

[0034] Figure 2 It is a top view of the three-dimensional electrochemical device.

[0035] Reference Numerals:

[0036] Electrolytic cell 1; Aeration pipe 2; Power supply 3; Anode plate 4; Cathode plate 5; Insulating basket 6; Boron carbide particles 7; Insulating partition plate 8; Water inlet 9; Water outlet 10; Sludge hopper 11; Sludge outlet 12; Circulation water inlet 13; Circulation water outlet 14; Circulation pump 15; On-line pH meter 16; Dosing pump 17; Ferrous sulfate storage tank 18; Hydrogen peroxide storage tank 19; Sulfuric acid solution storage tank 20; Hydroxylamine hydrochloride storage tank 21; Aeration branch pipe 22; Fixing rack 23. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] In the following text, only some exemplary embodiments are briefly described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0038] Figure 1 It is a schematic structural diagram of a three-dimensional electrochemical device of a boron carbide particle electrode according to a preferred embodiment of the present invention.

[0039] In a first aspect, the present invention provides a method for preparing a boron carbide particle electrode, comprising the steps of:

[0040] Stir and mix boron carbide powder, carbon black powder, a catalyst, and a granulation aid to obtain a premix;

[0041] Granulate the premix to agglomerate the granulation aid with the boron carbide powder, the catalyst, and the carbon black powder to obtain premix particles;

[0042] Dry the premix particles;

[0043] Calcine the dried premix particles at a high temperature to obtain boron carbide particles.

[0044] The boron carbide particles prepared in the embodiments of the present invention have the characteristics of high reduction activity, high stability, and electrical conductivity.

[0045] In a specific embodiment, the granulation aid includes a surfactant, a pore-forming agent, and a binder; wherein, by mass, the premix includes 90 - 100 parts of boron carbide powder, 2 - 4 parts of carbon black powder, 1 - 2.5 parts of surfactant, 5 - 10 parts of catalyst, 2 - 5 parts of pore-forming agent, and 0.5 - 1 part of binder, and the boron carbide powder is nanoscale with an average particle size of 50 nm; the average particle size of the carbon black powder is 20 nm.

[0046] In a specific embodiment, the catalyst includes at least one of nano titanium oxide (TiO₂), nano tin oxide (SnO₂), and nano zirconium oxide (ZrO₂), the particle size of the catalyst is 10 - 50 nm, the surfactant includes one or more of stearic acid, ammonium polyacrylate, and tetramethylammonium hydroxide, the pore-forming agent includes polyethylene glycol, and the binder includes a combination of high-density polyethylene and ethylene-vinyl acetate copolymer, and the mass percentage of high-density polyethylene and ethylene-vinyl acetate is 1:1.

[0047] In a specific embodiment, the time for stirring and mixing the boron carbide powder, the catalyst, the carbon black powder, and the granulation aid is 10 - 20 hours;

[0048] The step of granulating the premix includes:

[0049] Stir the premix at a rate of 20 - 40 r / min for 35 - 45 min;

[0050] Increase the rotation speed to 40 - 50 r / min and continue stirring for 1 - 2 h;

[0051] During the stirring process, the elevation angle of the turntable of the granulator is 30 - 75°;

[0052] The steps for drying the premix include:

[0053] Dry the premix at a temperature of 80 - 110°C for 4 - 6 h;

[0054] The steps for high-temperature calcination of the dried premix particles include:

[0055] Under nitrogen protection, conduct high-temperature calcination at 500 - 600°C for 4 - 8 h.

[0056] Examples of the preparation method

[0057] The present invention provides a method for preparing a boron carbide particle electrode, comprising the following steps:

[0058] In the first step, weigh 100 g of nano boron carbide powder, 4 g of carbon black powder, 2.5 g of surfactant ammonium polyacrylate, at least one of the catalysts nano titanium dioxide (TiO2), nano tin oxide (SnO2), nano zirconium oxide (ZrO2) with a weight of 5 g, the pore-forming agent includes polyethylene glycol, and the polyethylene glycol is 2 - 5 g, and a binder of high-density polyethylene and ethylene-vinyl acetate copolymer with a mass percentage of 1:1 is 1 g, at a temperature of 25°C, and mix and stir for 20 hours.

[0059] In the second step, place the above-mentioned premix in a pan granulator. When adjusting the rotation speed of the pan granulator, first stir at a rate of 20 r / min for 35 min; then increase the rotation speed to 40 r / min and continue stirring for 1 h, so that the binder agglomerates the boron carbide, catalyst and carbon black powder to obtain premix particles; the elevation angle of the turntable of the pan granulator is 30°; control the particle size to be 2 - 4 mm.

[0060] In the third step, after granulation, place the above-mentioned premix particles in a blast drying oven and dry them at a temperature of 80°C for 4 h to obtain dry spherical particles.

[0061] In the fourth step, put the dried spherical particles into a tubular furnace, conduct high-temperature calcination at 500 - 600°C for 4 hours under nitrogen protection, and cool with the furnace to obtain boron carbide particles with a particle size of 2 - 4 mm.

[0062] In a second aspect, the present invention provides a three-dimensional electrochemical device, which includes boron carbide particles prepared by the method for preparing boron carbide particles in the above embodiments, and the boron carbide particles are filled as three-dimensional electrodes in the three-dimensional electrochemical device.

[0063] In a specific embodiment, as shown in Figure 1 the three-dimensional electrochemical device further includes an electrolytic cell 1, an electrode unit, and a chemical dosing unit.

[0064] As shown in Figure 1 the electrolytic cell 1 includes a water inlet 9 and a water outlet 10; the electrolytic cell 1 has a bottom-in and top-out tank structure. It further includes a water circulation system, which includes a circulating water inlet 13, a circulating water outlet 14, and a circulation pump 15. The circulating water inlet 13 is arranged in the middle of one side wall of the electrolytic cell 1, and the circulating water outlet 14 is located in the middle of the side wall opposite to the circulating water inlet 13. The circulating water inlet 13 and the circulating water outlet 14 are connected to an external circulation pump 15 through a pipeline. The circulation ratio of the circulation pump 15 is 50 - 500%, and the water circulation system is beneficial to the full treatment of the concentrated water in the electrolytic cell 1.

[0065] As shown in Figure 1 and Figure 2 the electrode unit is arranged in the electrolytic cell 1. The electrode unit includes an anode plate 4, a cathode plate 5, and the boron carbide particles 7. The anode plate 4 and the cathode plate 5 are alternately arranged at intervals through a fixing frame 23, and the anode plate 4 and the cathode plate 5 are parallel to the water flow direction in the electrolytic cell 4. The boron carbide particles 7 are filled as three-dimensional electrodes between the anode plate 4 and the adjacent cathode plate 5 to form a three-dimensional electrode reaction chamber; wherein, both the anode plate 4 and the cathode plate 5 are connected to a power supply 3. Among them, according to the sewage to be treated, the filling amount of the boron carbide particles 7 can also be adjusted. If the amount of pollutants to be removed is small, the number of layers of the filled boron carbide particles 7 can be reduced; the boron carbide particles 7 are particle fillers with a high specific surface area and pore volume, which can be repolarized between the cathode plate 5 and the anode plate 4 to form particle electrodes with positive and negative charges at both ends, thereby playing the roles of the anode and cathode, and electrocatalytically oxidizing organic matter and nitrogen in water as multiple microelectrodes.

[0066] In the embodiment of the present invention, the power supply 3 is a constant current power supply mode and a reversible DC power supply. The power supply 3 is connected to each anode plate 4 and cathode plate 5 through wires to achieve individual control of each plate. The number of plates participating in the reaction can be controlled according to the water quality. The current density is 2 - 100 mA / cm 2 , and the electrode passivation is slowed down by reversing the polarity; the power supply 3 can control the switching time and the polarity reversal time regularly to activate the electrode by reversing the polarity.

[0067] As shown inFigure 1 As shown, the chemical dosing unit is connected to the electrolytic cell 1, and the chemical dosing unit is used to dose Fenton chemicals and control the pH value in the electrolytic cell 1.

[0068] The present invention utilizes the characteristics of the prepared boron carbide particles, which have high reduction activity, high stability and conductivity. Moreover, in a three-dimensional electrochemical device, through the three-dimensional electrode composed of the anode, cathode plates and the prepared boron carbide particles filled between the two, and the dosing of hydroxylamine hydrochloride, it can effectively promote the iron cycle in electrochemical Fenton oxidation and the conversion of nitrate to nitrogen, inhibit the reaction of hydroxylamine hydrochloride to generate nitrate, achieve the purpose of synchronously and efficiently removing organic matter and nitrogen in the concentrated wastewater, and at the same time, the good conductivity of the prepared boron carbide particles can also effectively improve the current efficiency.

[0069] In a specific embodiment, refer to Figure 1 As shown, the cross-section at the bottom of the electrolytic cell 1 gradually narrows to form a sludge discharge hopper 11 with a funnel-shaped sludge discharge area, and a sludge discharge port 12 is opened below the sludge discharge hopper 11. In the embodiment of the present invention, a sludge discharge hopper 11 can be provided at the bottom of the electrolytic cell 1, the inclination angle of the sludge discharge hopper is 30 - 60°, and a sludge discharge port 12 is opened directly below the sludge discharge hopper 11. The sludge generated when the electrolytic cell 1 treats wastewater can fall to the sludge discharge hopper 11 by gravity, and the sludge discharge can be realized by regularly opening the sludge discharge port 12.

[0070] In a specific embodiment, refer to Figure 1 and Figure 2 As shown, an aeration pipeline 2 connected to an external aerator is provided in the electrolytic cell 1. A number of aeration branch pipes 22 are provided on the aeration pipeline 2, and the aeration branch pipes 22 are connected to the bottom of the three-dimensional electrode reaction chamber in the electrode unit. The aeration branch pipes 22 are used to supply oxygen to the three-dimensional electrode reaction chamber. Aeration can supplement the oxygen in the sewage, promote the generation of strong oxidizing substance hydrogen peroxide, prevent the boron carbide particle electrodes from caking, improve the mass transfer efficiency of pollutants, and enhance the efficiency of the reactor in degrading pollutants. Specifically, the aeration volume is 0.1 - 1 L / min, and intermittent aeration can be carried out.

[0071] In a specific embodiment, refer to Figure 1As shown, a detachable insulating basket 6 with pores is arranged between the adjacent anode plate 4 and the cathode plate 5. The pore diameter of the insulating basket 6 is smaller than the diameter of the boron carbide particles 7. A number of insulating partition plates 8 are arranged in the insulating basket 6 to divide the insulating basket 6 into multiple compartments, and each compartment is filled with boron carbide particles 7 as electrodes. Specifically, the particle size of the boron carbide particles 7 is 2-4 mm; the filling density of the boron carbide particles 7 in the three-dimensional electrode reaction chamber is 100-800 g / L. Specifically, the distance between the insulating partition plates 8 is 10-30 cm, and the material of the insulating partition plates 8 can be PVC.

[0072] Furthermore, to reduce the dosage of externally added ferrous, the material of at least one anode plate 4 can be iron plate, and the materials of the remaining anode plates 4 are one of titanium coated with lead dioxide, titanium coated with ruthenium iridium, titanium coated with iridium tantalum in DSA electrodes or DBB electrodes; at the same time, the material of the cathode plate 5 is one of titanium, graphite, and graphite felt. In the reaction chamber with an iron anode, the iron electrode can be connected to the power supply or can be used as an induction electrode without being connected to the power supply. Iron loses electrons at the anode to form metal cations Fe 2+ , Fe generated at the anode or externally added 2+ reacts with hydrogen peroxide that can be generated or externally added at the cathode under acidic conditions to undergo a Fenton reaction, generating strongly oxidizing hydroxyl radicals to oxidize and remove organic matter in the sewage. The boron carbide particles 7 cooperate with hydroxylamine hydrochloride to accelerate the conversion of Fe 3+ into Fe 2+， , further promoting hydrogen peroxide to generate more hydroxyl radicals. At the same time, the boron carbide particles 7 can promote the conversion of nitrate nitrogen in the sewage into nitrogen or ammonia nitrogen, inhibit the reaction of hydroxylamine hydrochloride to generate nitrates. When the sewage contains chloride ions, active chlorine can be formed in the reactor to oxidize ammonia nitrogen into nitrogen, thereby achieving the removal of total nitrogen.

[0073] In a specific embodiment, refer to Figure 1As shown in the figure, the chemical dosing unit includes a ferrous sulfate storage tank 18, a hydrogen peroxide storage tank 19, a sulfuric acid storage tank 20, a hydroxylamine hydrochloride storage tank 21, a dosing pump 17, and an on-line pH meter 16; the ferrous sulfate storage tank 18, the hydrogen peroxide storage tank 19, the sulfuric acid storage tank 20, and the hydroxylamine hydrochloride storage tank 21 are connected to the electrolytic cell 1 through a chemical dosing pipe, and the dosing pump 17 is used to control the chemical dosing amounts of the ferrous sulfate storage tank 18, the hydrogen peroxide storage tank 19, the sulfuric acid storage tank 20, and the hydroxylamine hydrochloride storage tank 21. The ferrous sulfate storage tank 18 is used to store a ferrous sulfate solution with a solution concentration of 0.1 - 0.5 mol / L, the hydrogen peroxide storage tank 19 is used to store a hydrogen peroxide solution with a concentration of 5% - 27.5%, the sulfuric acid storage tank 20 is used to store a sulfuric acid solution with a concentration of 50%, and the hydroxylamine hydrochloride storage tank stores a 10% - 20% solution. The on-line pH meter 16 is used to display the pH value in the electrolytic cell 1 and can automatically start and stop the dosing of sulfuric acid according to the preset high or low pH value.

[0074] The following uses actual examples to detect and illustrate the wastewater treatment capacity of the boron carbide particle electrode three-dimensional electrochemical device.

[0075] Example 1: Preparation of the boron carbide particle electrode group ratio: 100 g of nano boron carbide powder, 4 g of carbon black powder, 2.5 g of surfactant ammonium polyacrylate, 5 g of catalyst nano titanium dioxide (TiO2), 2 g of pore-forming agent polyethylene glycol, and 1 g of binder of high-density polyethylene and ethylene-vinyl acetate copolymer with a mass percentage of 1:1.

[0076] Use the prepared boron carbide electrode particles to treat printing and dyeing reverse osmosis concentrate water with a COD of 650 mg / L, total nitrogen of 70 mg / L, conductivity of 20 ms / cm, TDS of 13.8 g / L, an anode BDD electrode and an iron plate induction electrode, a cathode graphite felt electrode, the distance between the anode and the cathode is 7 cm, the filling amount of boron carbide particle electrodes is 600 g / L, the internal circulation water volume ratio in the electrolytic cell is 300%, the pH value of the reaction is 3.5, 300 mg / L of hydrogen peroxide is added, 40 mg / L of hydroxylamine hydrochloride, and the current density is 10 mA / cm 2 When a constant current is applied for 2 hours, the effluent COD is 90 mg / L, the effluent total nitrogen is 10 mg / L, the COD removal rate is 86%, and the nitrate removal rate is 86%.

[0077] Example 2: Preparation of the boron carbide particle electrode group ratio: 100 g of nano boron carbide powder, 4 g of carbon black powder, 2.5 g of surfactant ammonium polyacrylate, 5 g each of catalyst nano titanium dioxide (TiO2) and nano tin oxide (SnO2), 2 g of pore-forming agent polyethylene glycol, and 1 g of binder of high-density polyethylene and ethylene-vinyl acetate copolymer with a mass percentage of 1:1.

[0078] The biochemical secondary sedimentation effluent of a pharmaceutical enterprise in Shandong was treated with the boron carbide electrode particles prepared above. The COD was 356 mg / L, the nitrate nitrogen was 32 mg / L, the conductivity was 4.28 ms / cm, the anode was a titanium-plated iridium-tantalum electrode, the cathode was a titanium plate electrode, the distance between the anode and the cathode was 7 cm, the filling amount of the boron carbide particle electrode was 500 g / L, the air flow rate of the aeration pipe was adjusted to 0.6 L / min, the circulation ratio of the circulation pump was 300%, the pH value of the reaction was 3.5, and a constant current of 7 mA / cm was applied to the cathode by an external power supply. 2 When the reaction lasted for 40 minutes, the effluent COD was 80 mg / L and the total nitrogen in the effluent was 8 mg / L.

[0079] Example 3: The reverse osmosis concentrate of a petrochemical plant was treated with the boron carbide electrode particles prepared in Example 2. The COD was 120 mg / L, the nitrate nitrogen was 50 mg / L, the conductivity was 2 ms / cm, the anode was a titanium-plated iridium-ruthenium electrode, the induction electrode was an iron plate, the cathode was a graphite electrode, the distance between the anode and the cathode was 10 cm, the filling amount of the boron carbide particle electrode was 600 g / L, and the circulation ratio of the circulation pump was 200%; 50 mg / L of hydrogen peroxide and 30 mg / L of hydroxylamine hydrochloride were added, the pH value of the reaction was 4, and the current density was 5 mA / cm. 2 When the reaction lasted for 60 minutes, the effluent COD was 25 mg / L, the total nitrogen in the effluent was 10 mg / L, the COD removal rate was 79%, and the nitrate removal rate was 80%.

[0080] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0081] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0082] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various changes or substitutions, and these should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims described above.

Claims

1. A three-dimensional electrochemical device, characterized in that, It includes boron carbide particles prepared by the following preparation method of boron carbide particles, and the boron carbide particles are filled as three-dimensional electrodes in the three-dimensional electrochemical device; The preparation method of the boron carbide particles includes the steps: Stir and mix boron carbide powder, carbon black powder, catalyst and granulation aid to obtain a premix; Granulate the premix to agglomerate the granulation aid with boron carbide powder, catalyst and carbon black powder to obtain premix particles; Dry-treat the premix particles; Calcine the dry-treated premix particles at high temperature to obtain boron carbide particles; The granulation aid includes a surfactant, a pore-forming agent and a binder; wherein, by mass, the premix includes 90-100 parts of boron carbide powder, 2-4 parts of carbon black powder, 1-2.5 parts of surfactant, 5-10 parts of catalyst, 2-5 parts of pore-forming agent and 0.5-1 part of binder, and the boron carbide powder is nanoscale with an average particle size of 50 nm; the average particle size of the carbon black powder is 20 nm; The catalyst includes at least one of nano titanium oxide (TiO2), nano tin oxide (SnO2), nano zirconium oxide (ZrO2), and the binder includes a combination of high-density polyethylene and ethylene-vinyl acetate copolymer, and the mass percentage of high-density polyethylene and ethylene-vinyl acetate is 1:

1.

2. The three-dimensional electrochemical device according to claim 1, characterized in that, The particle size of the catalyst is 10-50 nm, the surfactant includes one or more of stearic acid, ammonium polyacrylate and tetramethylammonium hydroxide, and the pore-forming agent includes polyethylene glycol.

3. The three-dimensional electrochemical device according to claim 1, wherein The time for stirring and mixing boron carbide powder, catalyst, carbon black powder and granulation aid is 10-20 hours; The step of granulating the premix includes: Stir the premix at a rate of 20-40 r / min for 35-45 min; Then increase the rotation speed to 40-50 r / min and continuously stir for 1-2 h; Wherein, the elevation angle of the turntable of the granulator during the stirring process is 30-75°; The step of dry-treating the premix includes: Dry the premix at a temperature of 80-110 °C for 4-6 h; The step of calcining the dry-treated premix particles at high temperature includes: Calcine at high temperature of 500-600 °C for 4-8 h under nitrogen protection.

4. The three-dimensional electrochemical device according to claim 1, characterized in that, It further includes: An electrolytic cell, the electrolytic cell includes a water inlet and a water outlet; the electrolytic cell is a bottom-in and top-out tank structure; An electrode unit, the electrode unit is arranged in the electrolytic cell, the electrode unit includes an anode plate, a cathode plate and the boron carbide particles, the anode plate and the cathode plate are arranged alternately at intervals, and the anode plate and the cathode plate are parallel to the water flow direction in the electrolytic cell, and the boron carbide particles are filled as three-dimensional electrodes between the anode plate and the adjacent cathode plate to form a three-dimensional electrode reaction chamber; wherein, both the anode plate and the cathode plate are connected to a power supply; A chemical dosing unit, the chemical dosing unit is communicated with the electrolytic cell, and the chemical dosing unit is used for dosing Fenton reagent and controlling the pH value in the electrolytic cell.

5. The three-dimensional electrochemical device according to claim 4, wherein, The cross-section at the bottom of the electrolytic cell gradually narrows to form a sludge discharge hopper with a funnel-shaped sludge discharge area, and a sludge discharge port is opened below the sludge discharge hopper.

6. The three-dimensional electrochemical device according to claim 4, characterized in that, An aeration pipeline connected to an external aerator is provided in the electrolytic cell. A number of aeration branch pipes are arranged on the aeration pipeline. The aeration branch pipes are communicated with the bottom of the three-dimensional electrode reaction chamber in the electrode unit, and the aeration branch pipes are used to supply oxygen to the three-dimensional electrode reaction chamber.

7. The three-dimensional electrochemical device according to claim 4, wherein A detachable insulating basket with pores is arranged between adjacent anode plates and cathode plates. The pore diameter of the insulating basket is smaller than the diameter of the boron carbide particles. A number of insulating partition plates are arranged in the insulating basket to divide the insulating basket into multiple compartments, and boron carbide particles are filled in each compartment as electrodes. The anode plate includes one or more of a reticulated DSA, BDD, and an iron plate electrode. The cathode plate includes one or more of graphite, graphite felt, a titanium plate, and a copper-based material. Among them, when the anode plate is an iron electrode, the anode plate is connected to the power supply, or the anode plate is not connected to the power supply as an induction electrode.

8. The three-dimensional electrochemical device according to claim 4, characterized in that, The chemical dosing unit includes a ferrous sulfate storage tank, a hydrogen peroxide storage tank, a sulfuric acid storage tank, a hydroxylamine hydrochloride storage tank, a dosing pump, and an on-line pH meter. The ferrous sulfate storage tank, the hydrogen peroxide storage tank, the sulfuric acid storage tank, and the hydroxylamine hydrochloride storage tank are connected to the electrolytic cell through a dosing pipe. The dosing pump is used to control the chemical dosing amount of the ferrous sulfate storage tank, the hydrogen peroxide storage tank, the sulfuric acid storage tank, and the hydroxylamine hydrochloride storage tank. The on-line pH meter is used to control the pH value in the electrolytic cell.

Images