Biochar materials, methods of making and using the same, gas permeable electrodes, and gas-lift electroozone devices

Abstract

The present application belongs to the technical field of electric ozone, and particularly relates to a biochar material, a preparation method and application thereof, a gas penetration type electrode and a gas-lift liquid flow type electric ozone device. The present application can obtain higher catalytic activity than conductive carbon black by modifying biochar, and is applied to electric ozone technology, thereby further reducing cost. The gas penetration type electrode prepared by using the biochar material as a catalyst is applied to the gas-lift liquid flow type electric ozone device, and in actual application, can improve the gas dispersion system, strengthen the mass transfer of ozone and oxygen to the electrode, increase the utilization rate of ozone and oxygen, realize the effect of simultaneously improving degradation efficiency and reducing energy consumption, and promote the large-scale application of electric ozone in degrading pollutants.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electric ozone, and particularly relates to a biochar material and a preparation method and application thereof, a gas penetration type electrode and a gas-lift liquid flow type electric ozone device. BACKGROUND

[0002] With the acceleration of industrialization and rapid population growth, water pollution problems are becoming increasingly serious. Traditional water treatment technologies, such as adsorption, coagulation, filtration and other physical treatment technologies, can only change the physical state of pollutants, but cannot completely convert them into harmless substances. Biological treatment technologies, such as activated sludge method, have limited treatment effect on some refractory organic matter and micro-pollutants (such as environmental endocrine disruptors, pharmaceuticals and personal care products, etc.), and it is difficult to achieve the expected purification effect. Therefore, it is urgent to find efficient, economical and environmentally friendly water treatment technologies.

[0003] Ozone, as a strong oxidizing agent, can effectively degrade a variety of pollutants and its decomposition product is oxygen, which does not produce toxic by-products and can increase the dissolved oxygen in water, so it has attracted widespread attention in the field of water treatment. In addition to traditional ozone oxidation technology, many advanced oxidation technologies have been developed in recent years, including ozone catalytic oxidation, O3 / UV, O3 / H2O2, electric ozone and other ozone coupling technologies. Among them, electric ozone technology uses hydrogen peroxide generated by two-electron oxygen reduction reaction at the cathode to react with ozone to produce hydroxyl radicals (·OH). Hydroxyl radical is a kind of active substance with strong oxidizing ability, which can efficiently degrade a variety of organic pollutants. This technology not only realizes efficient degradation of pollutants, but also avoids the additional step of adding hydrogen peroxide, avoids the explosion risk in hydrogen peroxide transportation, simplifies the processing flow and reduces the operation cost, and is considered as a promising water treatment technology.

[0004] The device of electric ozone includes an ozone generating device and a reaction device, and the reaction device includes an immersed electrode (cathode and anode), an aeration device and a stirring device. The cathode of the traditional electric ozone device uses carbon black-polytetrafluoroethylene electrode, in which the conductive carbon black is expensive, which limits the application of the method. In addition, since carbon atom is neutral, its adsorption or activation of O2 and intermediates generated in the process of two-electron oxygen reduction reaction is inert, which limits the activity of two-electron oxygen reduction reaction, resulting in low catalytic activity of conductive carbon black. SUMMARY

[0005] The present application aims to provide a biochar material, a preparation method and application thereof, a gas penetration electrode and a gas-lift liquid flow type electric ozone device, the biochar material provided by the present application has higher catalytic activity, the biochar material provided by the present application is used as a catalyst to make a gas penetration electrode applied to an electric ozone technology, on the basis of obtaining excellent degradation effect, the production cost is reduced and the gas mass transfer efficiency is improved.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] The present application provides a biochar material, comprising a biochar base body and an active component loaded in the biochar base body.

[0008] The active component comprises a metal element and a metal ion.

[0009] The metal element and the metal ion have the same type of metal element.

[0010] The metal element comprises a transition metal element, and the transition metal element comprises iron, manganese, copper, zinc, cobalt or nickel.

[0011] Preferably, the atomic content of the metal element in the active component is 10% to 20%.

[0012] The atomic content of the active component in the biochar material is 0.5% to 2%.

[0013] Preferably, the biochar material is further doped with nitrogen element, and the atomic content of the nitrogen element in the biochar material is 2% to 10%.

[0014] The present application further provides a preparation method of the biochar material according to the above technical scheme, comprising:

[0015] Mixing a biomass raw material and a metal salt, and calcining to obtain the biochar material.

[0016] The metal salt comprises a transition metal salt, and the transition metal salt comprises an iron salt, a manganese salt, a copper salt, a zinc salt, a cobalt salt or a nickel salt.

[0017] Preferably, the biomass raw material comprises one or more of chitosan, sodium alginate, gelatin, plant residues, wood and bamboo; the plant residues comprise one or more of tea residues, olive residues, coffee residues, peels, straws and shells.

[0018] The calcination temperature is 800 to 900 DEG C, and the holding time is 40 to 90 min; the calcination is carried out in a protective atmosphere.

[0019] The application further provides application of the biochar material in the preparation of a cathode of an electric ozone device as a catalyst.

[0020] The application further provides a gas-permeable electrode, comprising a porous gas-permeable layer and a porous catalyst layer which are sequentially stacked.

[0021] The material of the porous catalyst layer comprises a catalyst and a binder;

[0022] The catalyst is the biochar material or the biochar material prepared by the preparation method.

[0023] Preferably, the content of the catalyst in the gas-permeable electrode is 0.5-5 mg / cm 2 .

[0024] The application further provides a gas-lift liquid-flow electric ozone device, comprising a reaction tower 12 and an ozone generator device which is in communication with the bottom end of the reaction tower 12.

[0025] The lower part of the reaction tower 12 is horizontally provided with a cathode 6, and the cathode 6 is the gas-permeable electrode according to the above technical solution, and the porous gas-permeable layer of the gas-permeable electrode is arranged downward.

[0026] The upper part of the reaction tower 12 is horizontally provided with an anode 8, and the cathode 6 and the anode 8 form a closed reaction chamber 7 with the side wall of the reaction tower 12.

[0027] Preferably, the anode 8 is a coated titanium electrode.

[0028] The bottom end of the reaction tower 12 is provided with an air inlet 5.

[0029] The ozone generator device comprises an oxygen cylinder 1 and an ozone generator 2 which are sequentially in communication, and the ozone generator 2 is in communication with the air inlet 5.

[0030] The application provides a biochar material, which comprises a biochar base body and active ingredients loaded in the biochar base body; the active ingredients comprise metal elements and metal ions; the metal elements in the metal elements and the metal ions are of the same type; the metal elements comprise transition metal elements, and the transition metal elements comprise iron, manganese, copper, zinc, cobalt or nickel. The biochar is modified by using the metal elements and the metal ions, so that higher catalytic activity than that of conductive carbon black can be obtained, the application in electric ozone technology can further reduce the cost and promote the large-scale application of the electric ozone technology; meanwhile, the biochar material can realize the revaluation of biomass and is of great significance for solid waste management.

[0031] This invention also provides a gas-permeable electrode, comprising a porous permeable layer and a porous catalyst layer stacked sequentially; the porous catalyst layer is made of a catalyst and a binder; the catalyst is the biochar material described in the above-described technical solution or the biochar material prepared by the preparation method described in the above-described technical solution. In this invention, the gas-permeable electrode has significant advantages in increasing gas utilization. Traditional immersion electrodes, due to their structural limitations and the accessibility of gaseous substances, mainly rely on dissolved oxygen and ozone in water for the reaction. However, the solubility of oxygen and ozone in water is relatively low, causing a large amount of gas to escape from the liquid surface into the air, thus greatly reducing the gas utilization efficiency. In contrast, the gas-permeable electrode can utilize not only dissolved oxygen and ozone but also gaseous oxygen and ozone directly. This is because in the gas-permeable electrode, gaseous oxygen and ozone must first pass through the catalyst layer of the electrode before entering the solution. This process forms a three-phase reaction interface in the catalyst layer, namely a gas-liquid-solid three-phase interface, where the electrode reaction occurs. In this way, gas-permeable electrodes can effectively utilize gaseous substances, thereby significantly improving gas utilization. Due to the increased gas utilization, gas-permeable electrodes not only enhance the reaction rate but also reduce overpotential and energy input. In other words, gas-permeable electrodes exhibit significant advantages in catalytic efficiency, energy utilization, and reaction effects. These advantages make gas-permeable electrodes a promising candidate for applications in electro-ozone generation.

[0032] This invention also provides a gas-lift liquid flow electro-ozone device, including a reaction tower 12 and an ozone generator connected to an air inlet 5 at the bottom of the reaction tower. The bottom of the reaction tower 12 includes a horizontally arranged cathode 6, which is a gas-penetrating electrode as described in the above-mentioned technical solution. The porous permeable layer of the gas-penetrating electrode is located above the air inlet 5 at the bottom of the reaction tower and forms a sealed space with the side wall of the reaction tower 12. The top of the reaction tower 12 includes a horizontally arranged anode 8, and a reaction chamber 7 is formed between the cathode 6 and the anode 8. In this invention, the gas-lift liquid flow electro-ozone device can further improve the utilization rate of oxygen and ozone. The key to the device is that the gas-penetrating electrode is placed horizontally, and the gas passes through the electrode from bottom to top, then rises using its own buoyancy. This design cleverly utilizes the internal pressure characteristics of the liquid and the diffusion characteristics of bubbles in the liquid, significantly improving the reaction efficiency. After passing through the gas-penetrating electrode, the gas forms bubbles, which diffuse to the solution surface, undergoing mass transfer with the liquid to generate dissolved oxygen and ozone. The contact time is determined by the diffusion path length of the bubbles; the longer the path, the more dissolved oxygen and ozone. When the electrode is placed vertically, the liquid pressure at the top is the lowest, making it easier for gas to enter from the top, forming short-path bubbles and resulting in less dissolution. When the electrode is placed horizontally at the bottom of the reactor, the liquid pressure is uniform and at its maximum, allowing gas to pass through the electrode from the bottom, extending the bubble path, increasing the contact time, maximizing the dissolution, and making the bubble distribution more uniform. This helps to further improve reaction efficiency and reduce energy consumption without relying on additional stirring devices.

[0033] The gas-penetrating electrode and gas-lift liquid flow electro-ozone device provided by this invention optimize electrode design and improve gas dispersion system, enhance mass transfer of ozone and oxygen to the electrode, increase the utilization rate of ozone and oxygen, and achieve the effect of simultaneously improving degradation efficiency and reducing energy consumption, thereby promoting the expanded application of electro-ozone in degrading pollutants. Attached Figure Description

[0034] Figure 1 Here is a SEM image of the biochar material obtained in Example 1;

[0035] Figure 2 The image shows the XRD pattern of the biochar material obtained in Example 1.

[0036] Figure 3 The image shows the hydrophobic carbon paper and gas-penetrating electrode used in Example 2.

[0037] Figure 4 This is a schematic diagram of the gas-penetrating electrode in this invention;

[0038] Figure 5This is a schematic diagram of the structure of the gas-lift liquid flow electro-ozone device in Embodiment 3 of the present invention, wherein 1 is an oxygen cylinder, 2 is an ozone generator, 3 is an ozone detector, 4 is a mass flow meter, 5 is an air inlet, 6 is a cathode, 7 is a reaction chamber, 8 is an anode, 9 is a tail gas chamber, 10 is a DC power supply, 11 is an ozone destruction chamber, 12 is a reaction tower, and 13 is an air outlet.

[0039] Figure 6 The LSV curves and H2O2 oxidation current test results of the two-electron oxygen reduction reaction of the biochar material obtained in Example 1 and commercially available conductive carbon black are shown.

[0040] Figure 7 The two-electron selectivity is calculated based on the LSV curve and the H2O2 oxidation current.

[0041] Figure 8 The diagram shows the degradation effect of ibuprofen by the airlift liquid flow electro-ozone device, the conventional ozone oxidation device, and the electrolysis device in Application Example 1.

[0042] Figure 9 The diagram shows the effect of decomposing ibuprofen at different current densities in the airlift liquid flow electro-ozone device in Example 2. Detailed Implementation

[0043] This invention provides a biochar material, comprising a biochar matrix and an active ingredient loaded in the biochar matrix;

[0044] The active ingredients include elemental metals and metal ions;

[0045] The metallic elements and metal ions contain the same type of metallic element.

[0046] The metallic element includes transition metal elements, which include iron, manganese, copper, zinc, cobalt, or nickel.

[0047] In this invention, the atomic content of the elemental metal in the active ingredient is preferably 10% to 20%, more preferably 15%. In this invention, the atomic content of the active ingredient in the biochar material is preferably 0.5% to 2%, more preferably 0.66% to 1.0%. In this invention, the biochar material is also preferably doped with nitrogen; the atomic content of nitrogen in the biochar material is preferably 2% to 10%.

[0048] In this invention, the biochar material has a porous structure. By modifying the biochar with elemental metals and metal ions, higher catalytic activity than conductive carbon black can be obtained.

[0049] The present invention also provides a method for preparing the biochar material described in the above technical solution, comprising the following steps:

[0050] Biomass raw materials and metal salts are mixed and calcined to obtain the biochar material;

[0051] The metal salts include transition metal salts, which include iron salts, manganese salts, copper salts, zinc salts, cobalt salts, or nickel salts.

[0052] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0053] In this invention, the biomass raw material preferably includes one or more of chitosan, sodium alginate, gelatin, plant residues, wood, and bamboo; the plant residue preferably includes one or more of tea residue, olive residue, coffee residue, fruit peel, straw, and fruit shells. In this invention, the nickel salt is further preferably NiCl2·6H2O. In this invention, the mass ratio of the biomass raw material to the transition metal salt is preferably 1–10:1, and more preferably 2:1.

[0054] In this invention, the mixing is preferably carried out under heating and stirring conditions, with the heating and stirring temperature preferably being 120°C and the time preferably being 8 hours. In this invention, the calcination temperature is preferably 800–900°C, and the holding time is preferably 40–90 minutes, more preferably 60 minutes; the calcination is preferably carried out under a protective atmosphere, preferably nitrogen or an inert gas. In this invention, the calcination is preferably carried out in a tubular furnace. In this invention, during the calcination process, the biomass raw material undergoes carbonization, with some metals anchored to the carbon substrate to form MNC bonds (M representing metal, i.e., metal ions), and other metals undergo thermal migration to form metal clusters (i.e., elemental metals).

[0055] After calcination, the present invention preferably further includes sequentially acid washing, water washing, drying, and ball milling of the calcined product; the acid used for acid washing is preferably hydrochloric acid, and the molar concentration of the hydrochloric acid is preferably 1 mol / L; the acid washing temperature is preferably 120°C, and the time is preferably 12 hours, which can remove excess impurities from the material surface; the water washing is preferably performed using deionized water until the washing solution is neutral. In the present invention, the drying temperature is preferably 80°C. In the present invention, the ball-to-material ratio for ball milling is preferably 1:1, the rotation speed is preferably 600 r / min, and the time is preferably 4 hours.

[0056] The present invention also provides the application of the biochar material described in the above technical solution or the biochar material prepared by the preparation method described in the above technical solution as a catalyst in the cathode of an electro-ozone device.

[0057] The present invention also provides a gas-penetrating electrode, comprising a porous gas-permeable layer and a porous catalyst layer stacked sequentially;

[0058] The porous catalyst layer is made of a catalyst and a binder;

[0059] The catalyst is the biochar material described in the above technical solution or the biochar material prepared by the preparation method described in the above technical solution.

[0060] In this invention, the porous breathable layer is preferably porous hydrophobic carbon paper, porous hydrophobic carbon felt, or porous hydrophobic carbon cloth. In this invention, the thickness of the porous breathable layer is preferably 0.1–0.3 mm, more preferably 0.19 mm.

[0061] In this invention, the binder preferably comprises polytetrafluoroethylene and / or perfluorosulfonic acid-polytetrafluoroethylene copolymer. In this invention, the catalyst content in the gas-permeable electrode is preferably 0.5–5 mg / cm³. 2 More preferably 1–3 mg / cm³ 2 .

[0062] In this invention, the gas-permeable electrode is preferably prepared by a spraying method; the spraying method preferably includes the following steps: mixing a catalyst, a binder solution and an organic solvent to obtain a slurry; placing the porous permeable layer on a preheated substrate; spraying the slurry onto one side of the porous permeable layer; and then drying and heat-treating to obtain the gas-permeable electrode.

[0063] In this invention, the organic solvent preferably includes anhydrous ethanol. In this invention, the mass concentration of the binder solution is preferably 60%; the volume of the binder solution is preferably 0.166% of the volume of the organic solvent. In this invention, the mass concentration of the catalyst in the slurry is preferably 4.536 g / L. In this invention, the mixing is preferably carried out under ultrasonic conditions. In this invention, the preheating temperature is preferably 110°C. This invention does not impose any special limitations on the spraying process; any process well known to those skilled in the art can be used. In this invention, the heat treatment temperature is preferably 330°C, and the holding time is preferably 30 min.

[0064] The present invention also provides an airlift liquid flow type electro-ozone device, including a reaction tower 12 and an ozone generator connected to the bottom end of the reaction tower 12;

[0065] A cathode 6 is horizontally arranged at the lower part of the reaction tower 12. The cathode 6 is a gas-penetrating electrode as described in the above technical solution, and the porous permeable layer of the gas-penetrating electrode is arranged downwards.

[0066] An anode 8 is horizontally arranged at the upper part of the reaction tower 12, and the cathode 6 and the anode 8 form a closed reaction chamber 7 between themselves and the side wall of the reaction tower 12.

[0067] In one embodiment of the present invention, the bottom end of the reaction tower 12 is provided with an air inlet 5.

[0068] In one embodiment of the present invention, the ozone generating device includes an oxygen cylinder 1 and an ozone generator 2 connected in sequence, and the ozone generator 2 is connected to the air inlet 5.

[0069] In one embodiment of the present invention, an ozone detector 3 and a mass flow meter 4 are further provided between the ozone generator 2 and the air inlet 5.

[0070] In this invention, during specific applications, the reaction chamber is filled with a solution to be treated. One side of the porous catalyst layer of the gas-penetrating electrode is in contact with the liquid. Gaseous oxygen and ozone must pass through the porous catalyst layer of the cathode before entering the reaction chamber. This process forms a three-phase reaction interface—a gas-liquid-solid interface—in the porous catalyst layer, where electrode reactions occur. In this way, the gas-penetrating electrode can effectively utilize gaseous substances, thereby significantly improving gas utilization. Due to the increased gas utilization, the gas-penetrating electrode not only improves the reaction rate but also reduces overpotential and energy input.

[0071] In one embodiment of the present invention, the anode 8 is preferably a coated titanium electrode. In the present invention, the coated titanium electrode preferably comprises a titanium substrate and a tantalum-iridium coating located on the surface of the titanium substrate; the thickness of the coated titanium electrode is preferably 1 mm, and the thickness of the tantalum-iridium coating is preferably 4–6 μm.

[0072] In one embodiment of the present invention, the cathode 6 and the anode 8 are preferably connected by a DC power supply 10.

[0073] In one embodiment of the present invention, the top of the reaction tower 12 is provided with an outlet 13, and an exhaust chamber 9 is formed between the anode 8 and the outlet 13. In another embodiment of the present invention, the outlet 13 is connected to an ozone destructor 11.

[0074] In an embodiment of the present invention, a schematic diagram of the gas-lift liquid flow electro-ozone device is shown below. Figure 5 As shown, 1 is an oxygen cylinder, 2 is an ozone generator, 3 is an ozone detector, 4 is a mass flow meter, 5 is an air inlet, 6 is a cathode, 7 is a reaction chamber, 8 is an anode, 9 is an exhaust chamber, 10 is a DC power supply, 11 is an ozone destruction chamber, 12 is a reaction tower, and 13 is an exhaust port.

[0075] In this invention, when the airlift liquid flow electro-ozone device is used to degrade organic pollutants, the preferred specific process of the degradation is as follows:

[0076] Step 1: After the oxygen flows out of the oxygen cylinder, it reaches the ozone generator, where some of the oxygen is converted into ozone, resulting in an ozone / oxygen mixture.

[0077] Step 2: The ozone / oxygen mixture passes sequentially through an ozone detector (to detect ozone concentration) and a mass flow meter (to control gas flow), and then enters the reaction tower through the inlet at the bottom of the reaction tower.

[0078] Step 3: The ozone / oxygen mixture passes through the gas-penetrating electrode (cathode) and undergoes a chemical reaction at the cathode: oxygen undergoes a two-electron oxygen reduction reaction at the cathode to generate hydrogen peroxide, while some ozone is directly reduced by the cathode to generate hydroxyl radicals; subsequently, hydrogen peroxide and hydroxyl radicals diffuse into the solution in the reaction chamber;

[0079] Hydrogen peroxide is produced: O2 + 2H + +2e - →H2O2

[0080] Ozone reduction generates hydroxyl radicals:

[0081]

[0082]

[0083] ·HO3→O2+·OH

[0084] Step 4: The remaining unreacted mixed gas diffuses into the solution and forms bubbles. Under the action of buoyancy, the bubbles rise and continue to come into contact with the solution and diffuse into the solution during the rising process, forming dissolved oxygen and ozone.

[0085] Step 5: Dissolved oxygen and ozone return to the cathode to undergo the reaction described in Step 3. At the same time, dissolved ozone and hydrogen peroxide react to generate hydroxyl radicals, which react with pollutants to degrade them.

[0086] 2O3 + H2O2 → 2·OH + 3O2

[0087] Step 6: The gas escaping from the solution enters the exhaust chamber, and is then treated by the ozone destroyer before being discharged.

[0088] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0089] Example 1

[0090] Chitosan and NiCl2·6H2O were mixed at a mass ratio of 2:1 and stirred at 120℃ for 8 hours until dry. The mixture was then placed in a tube furnace and calcined at 800℃ under a nitrogen atmosphere for 60 minutes. The calcined product was acid-washed with 1 mol / L HCl at 120℃ for 12 hours and washed repeatedly with deionized water until the washing solution was neutral. The product was dried in a vacuum oven at 80℃ and then ball-milled (ball-to-material ratio of 1:1, rotation speed of 600 r / min, time of 4 hours) to obtain biochar material.

[0091] Figure 1 SEM images of the obtained biochar material, from Figure 1 It can be seen that the obtained biochar material is an aggregate of irregular blocks or spherical particles, and has a porous structure on the surface.

[0092] The elemental content of the obtained biochar material was tested. C, H, and O were tested by XPS, and Ni was tested by ICP-OES. The test results are shown in Table 1.

[0093] Table 1. Elemental content of biochar materials obtained in Example 1

[0094] Material C (atom %) N (atom %) O (atom %) Ni (atom %) Ni@NC-0.50 87.25％ 2.73％ 9.35％ 0.66％

[0095] XPS Ni fine spectrum peak analysis showed that the atomic content of elemental nickel in nickel was 13%.

[0096] Figure 2 The XRD pattern of the obtained biochar material is shown from... Figure 2 It can be seen that the obtained biochar material contains Ni nanoparticles and is not a typical amorphous carbon material, but has a certain degree of graphitization.

[0097] The catalytic performance of biochar materials and commercially available conductive carbon black (model XFI15) on the two-electron oxygen reduction reaction was tested.

[0098] The test method is as follows: 5 mg of catalyst was accurately weighed and added to 2 mL of ethanol and 20 μL of Nafion solution. The solution was then subjected to ultrasonic testing at 100 W for 10 minutes to obtain a uniformly dispersed catalyst ink. 10 μL of the catalyst ink was then dropped twice onto a glassy carbon disk (0.2475 cm² area). 2(Collection efficiency 36%), after film formation, it was installed in an RRDE instrument for testing. RRDE measurements were performed using a potentiostat (PINE, USA) in a five-cell electrolytic cell. A glassy carbon electrode coated with a catalyst was used as the working electrode, an Hg / HgO electrode as the reference electrode, and a stone-ground rod electrode as the counter electrode. The electrolyte was 50 mL of 100 mM KOH solution. During the test, N2 was first introduced for 10 minutes to purge other gases from the solution. The working potential was maintained at 100 mV·s. -1 The electrode was activated by scanning cyclic voltammetry curves, repeated 20 times until a stable CV curve was obtained. Then, the voltammetry was increased at 200 mL / min. -1 O2 was introduced for 5 minutes to saturate the solution with dissolved oxygen, and the rotation speed of the RRDE device was set to 1600 r / min. The H2O2 oxidation current curve was obtained by scanning the It curve under constant potential (1.2V vs. RHE). Based on the obtained disk current and ring current, the 2e of the material can be calculated. - ORR selectivity is calculated using the following formula:

[0099]

[0100] Among them, I R It is the loop current, I D denoted as disk current, and N as electrode collection efficiency (calibrated to 36%).

[0101] The test results obtained are as follows Figure 6 and Figure 7 As shown, Figure 6 The LSV curves and H2O2 oxidation current test results for the two-electron oxygen reduction reaction of biochar materials and commercially available conductive carbon black are presented. Figure 7 The two-electron selectivity is calculated based on the LSV curve and the H2O2 oxidation current.

[0102] Depend on Figure 6 and Figure 7 It can be seen that the biochar material obtained by this invention has a higher hydrogen peroxide current and selectivity compared to commercially available conductive carbon black, indicating that the biochar material provided by this invention has higher catalytic activity. Therefore, the electrode provided by this invention can significantly reduce costs and promote the large-scale application of electro-ozone while improving catalytic activity.

[0103] Example 2

[0104] Gas-penetrating electrodes were prepared using the biochar material obtained in Example 1;

[0105] Under ultrasonic assistance, a 60% (w / w) PTFE solution and biochar material were uniformly dispersed in anhydrous ethanol (PTFE solution volume was 0.166% of ethanol volume; biochar material concentration was 4.536 g / L) to obtain a slurry. Porous hydrophobic carbon paper was placed on a heating plate at 110°C, and the slurry was evenly sprayed onto one side of the paper using an airbrush. After drying, the paper was heat-treated in a muffle furnace at 330°C for 30 minutes to obtain a gas-permeable electrode, wherein the biochar material content in the gas-permeable electrode was 1 mg / cm³. 2 .

[0106] Among them, the physical image of the porous hydrophobic carbon paper is as follows: Figure 3 As shown in (a), the thickness is 0.19 mm; a physical image of the gas-penetrating electrode is shown below. Figure 3 As shown in (b); structural schematic diagram as shown Figure 4 As shown, 1 is a porous hydrophobic carbon paper, and 2 is a porous catalyst layer.

[0107] Example 3

[0108] Using the gas-penetrating electrode obtained in Example 2 as the cathode, an air-lift liquid flow electro-ozone device was assembled (see schematic diagram of the device). Figure 5 (as shown);

[0109] The anode is a coated titanium electrode (the substrate is a titanium substrate, and the titanium coating is a 5μm thick tantalum-iridium coating);

[0110] The cathode and anode are horizontally positioned at the bottom and top of the reaction tower, respectively, with the porous permeable layer of the gas-penetrating electrode facing downwards; the cathode and anode form a closed reaction chamber with the side wall of the reaction tower; the cathode and anode are connected via a DC power supply.

[0111] A tail gas chamber is formed between the anode and the gas outlet of the reaction tower; the gas outlet of the reaction tower is connected to an ozone destroyer.

[0112] The air inlet of the reaction tower is connected in sequence to a mass flow meter, an ozone detector, an ozone generator, and an oxygen cylinder.

[0113] Application Example 1

[0114] Ibuprofen was degraded using the airlift-liquid flow electro-ozone device described in Example 3;

[0115] The initial concentration of ibuprofen was 20 mg / L, the solution was 0.05 M Na₂SO₄ solution, the gas flow rate was 40 mL / min, the ozone concentration was 70 mg / L, and the current density was 4 mA / cm². 2 .

[0116] A conventional ozone oxidation device and an electrolysis device with the same gas flow rate and ozone concentration are used as comparative examples; the ozone oxidation device is identical to the gas-lift liquid flow electro-ozone device of the present invention except that no current is applied. The electrolysis device is identical to the gas-lift liquid flow electro-ozone device of the present invention except that the ozone generator is not turned on.

[0117] Test results are as follows Figure 8 As shown, using the airlift-liquid flow electro-ozone device provided by this invention, high concentrations of ibuprofen can be completely removed within 15 minutes, requiring only 28 mA of current, resulting in extremely low energy consumption. In contrast, the ozone oxidation device in the comparative example achieved a degradation rate of 95% after 20 minutes, which is insufficient for complete removal. The electrolysis device achieved a degradation rate of 15% after 20 minutes. These results fully demonstrate the superior performance of the airlift-liquid flow electro-ozone device provided by this invention in degrading recalcitrant pollutants, indicating that this device has broad application prospects and high practical value in environmental protection and industrial wastewater treatment.

[0118] Application Example 2

[0119] Using the gas-lift liquid flow ozone generator described in Example 3, ibuprofen was degraded at different current densities. The initial ibuprofen concentration was 20 mg / L, the solution was a 0.05 M Na₂SO₄ solution, the gas flow rate was 40 mL / min, and the ozone concentration was 70 mg / L. The test results are as follows: Figure 9 As shown in Table 2;

[0120] Table 2. Effects of different current densities on ibuprofen dissolution

[0121]

[0122] As can be seen from Table 2, the airlift liquid flow ozone device provided by the present invention has better degradation efficiency than the traditional ozone oxidation method under different current densities.

[0123] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A gas-penetrating electrode, characterized in that, It includes a porous permeable layer and a porous catalyst layer stacked sequentially; the gas-penetrating electrode is used as the cathode of the electro-ozone device; The porous catalyst layer is made of a catalyst and a binder; The catalyst is a biochar material, which includes a biochar matrix and active components loaded in the biochar matrix; The active ingredients include elemental metals and metal ions; The metallic elements and metal ions contain the same type of metallic element. The metal element is a transition metal element, and the transition metal element is iron, manganese, copper, zinc, cobalt or nickel; The biochar material is also doped with nitrogen. The active ingredient has an atomic content of 10% to 20% of the elemental metal; the biochar material has an atomic content of 0.5% to 2% of the active ingredient; and the biochar material has an atomic content of 2% to 10% of the nitrogen element.

2. The gas-penetrating electrode according to claim 1, characterized in that, The method for preparing the biochar material includes the following steps: Biomass raw materials and metal salts are mixed and calcined to obtain the biochar material; The metal salt is a transition metal salt, which may be an iron salt, manganese salt, copper salt, zinc salt, cobalt salt, or nickel salt; the biomass raw material is chitosan.

3. The gas-penetrating electrode according to claim 2, characterized in that, The calcination temperature is 800~900℃, and the holding time is 40~90min; the calcination is carried out under a protective atmosphere.

4. The gas-penetrating electrode according to claim 1, characterized in that, The catalyst content in the gas-permeable electrode is 0.5~5 mg / cm³. 2 .

5. A gas-lift liquid flow electro-ozone generator, characterized in that, Includes a reaction tower (12) and an ozone generator connected to the bottom of the reaction tower (12); A cathode (6) is horizontally arranged at the lower part of the reaction tower (12), and the cathode (6) is a gas-penetrating electrode as described in any one of claims 1 to 4, wherein the porous permeable layer of the gas-penetrating electrode is arranged downward. An anode (8) is horizontally arranged at the top of the reaction tower (12), and the cathode (6) and the anode (8) form a closed reaction chamber (7) between them and the side wall of the reaction tower (12).

6. The gas-lift liquid flow electro-ozone device according to claim 5, characterized in that, The anode (8) is a coated titanium electrode; The bottom end of the reaction tower (12) is provided with an air inlet (5). The ozone generator includes an oxygen cylinder (1) and an ozone generator (2) connected in sequence, and the ozone generator (2) is connected to the air inlet (5).

Images