Three-dimensional integral electrode, preparation method thereof and method for degrading organic pollutants through electrochemical oxidation

Abstract

The invention provides an anode electrode. The anode electrode comprises a titanium substrate, a Sb-SnO2 intermediate layer and a SnOxFy active layer, wherein the Sb-SnO2 intermediate layer is compounded on the titanium substrate, and the SnOxFy active layer is compounded on the Sb-SnO2 intermediate layer. The invention designs a three-dimensional integral electrode based on a three-dimensional structure, construction of an intermediate transition layer and a fluorine element doping synergistic effect, and also provides a corresponding preparation method and application of the three-dimensional integral electrode in electrochemical oxidative degradation of organic pollutants. The prepared three-dimensional integral electrode has the advantages that the pollutant removal efficiency is high, the recycling stability is good, the influence of water quality conditions on the catalytic performance is small, the preparation method is simple, operation is easy to master, meanwhile, materials needed in the synthesis process are non-toxic and stable non-noble metal, and the cost is low. The performance of the three-dimensional integral electrode is not obviously reduced when the three-dimensional integral electrode is subjected to an experiment of cyclic electrochemical oxidative degradation of organic pollutants, so that the three-dimensional integral electrode has stable catalytic performance and conforms to green, economic and sustainable development concepts.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials for electrochemically oxidizing and degrading organic pollutants, and relates to an anode electrode and a preparation method thereof, a method for electrochemically oxidizing and degrading organic pollutants, and particularly relates to a three-dimensional integral electrode and a preparation method thereof, a method for electrochemically oxidizing and degrading organic pollutants. Background Art

[0002] Refractory organic pollutants (such as antibiotics, endocrine disruptors, etc.) widely exist in various water bodies and wastewaters, and these pollutants will seriously threaten the safety of the ecological system and the supply of clean water resources. The electrocatalytic oxidation technology driven by renewable energy provides a new idea for removing such pollutants. This technology has the advantages of strong oxidation ability, environmental friendliness, compact structure, fast reaction rate, and easy modularization, and is a potential method for treating refractory organic pollutants. During the electrocatalytic oxidation process, organic pollutants can be completely decomposed through direct electron transfer (direct oxidation) on the anode surface or by the oxidation of electrochemically generated active substances (such as ·OH, H2O2, etc.) (indirect oxidation).

[0003] However, due to the limitation of the pollutant mass transfer rate, the efficiency of the direct oxidation process is usually low. Indirect oxidation relies on the in-situ generation of highly active oxidation species (such as ·OH, H2O2, etc.) on the anode surface to degrade organic pollutants. During the indirect oxidation process, the generation efficiency of hydroxyl radicals on the anode surface mainly depends on the properties of the anode electrode material, so the design and selection of the electrode catalytic material are crucial.

[0004] Currently, in the field of electrochemical oxidation, a variety of anode materials have been studied and applied, including titanium-based coated noble metal oxide electrodes (such as Ti / RuO2-IrO2, also known as DSA anodes), lead-based lead dioxide (PbO2) electrodes, and boron-doped diamond (BDD) electrodes, etc. These anode materials have their own advantages and disadvantages: the PbO2 electrode has a low preparation cost, but there is a risk of secondary pollution caused by lead ion dissolution; the titanium-based noble metal oxide electrode has good conductivity and stability, but the noble metal components in it are expensive and are prone to inactivation under harsh conditions; the BDD electrode has extremely high oxidation ability and corrosion resistance, but the preparation cost is extremely high, the process is complex, and it is difficult to be applied on a large scale. In contrast, tin dioxide (SnO2)-based anodes have attracted much attention due to their high oxygen evolution overpotential, low cost, and non-toxicity, etc. Antimony-doped SnO2 (i.e., ATO) is a commonly used modified anode material, and doping antimony can significantly improve the conductivity of SnO2. However, the SnO2-based electrode still has deficiencies such as poor bonding force between the active coating and the substrate, easy shedding of the catalytic layer during long-term operation, and limited efficiency of single-electron water oxidation (generating ·OH).

[0005] Meanwhile, the structural morphology of the electrode is also a key factor affecting the performance. Traditional anodes mostly have a planar structure, with a limited specific surface area and a long mass transfer path, which is not conducive to improving the removal efficiency of refractory organic pollutants. In addition, in the existing technology, organic binders are often used to fix the catalyst on the electrode substrate, but the insulating properties of the binder will reduce the conductivity of the electrode and the utilization rate of the active sites of the catalyst, and its heat resistance and chemical resistance are also poor, resulting in the easy shedding of the catalyst on the electrode during long-term operation and the gradual decline of performance.

[0006] Therefore, how to develop a three-dimensional monolithic electrode material without a binder, with a firmly bonded catalytic active layer and a high specific surface area, to improve the electrochemical oxidation treatment efficiency of refractory organic pollutants has become one of the focuses widely concerned by many front-line researchers in the industry. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide an anode electrode and its preparation method, a method for electrochemically oxidizing and degrading organic pollutants, especially a three-dimensional monolithic electrode and its preparation method, a method for electrochemically oxidizing and degrading organic pollutants, and particularly a three-dimensional monolithic electrode. The three-dimensional monolithic electrode prepared by the present invention, including the synergistic effect of a three-dimensional structure, an intermediate transition layer, and fluorine element doping, has the advantages of high pollutant removal efficiency, good cycle use stability, and little influence of catalytic performance by water quality conditions. Moreover, the preparation method is simple, the conditions are mild, the controllability is good, the stability is strong, and it is more suitable for industrial promotion and application.

[0008] The present invention provides an anode electrode, which includes a titanium substrate, an Sb-SnO2 intermediate layer compounded on the titanium substrate, and an SnO x F y active layer;

[0009] Among them, 0 < x < 2, 0 < y < 4.

[0010] Preferably, the anode electrode is a three-dimensional monolithic electrode;

[0011] The thickness of the Sb-SnO2 intermediate layer is 80 - 120 μm;

[0012] The SnO x F y active layer has a thickness of 10 - 20 μm;

[0013] The titanium substrate is selected from at least one of titanium foam, titanium felt, and titanium sheet.

[0014] Preferably, in the anode electrode, the mass fraction of Sb-SnO2 is 25% - 45%;

[0015] In the anode electrode, the mass fraction of SnO x F y is 10% - 15%;

[0016] The anode electrode is specifically an anode electrode for electrochemically oxidizing and degrading organic pollutants.

[0017] The present invention provides a method for preparing an anode electrode, comprising the following steps:

[0018] 1) Mix a tin source, an antimony source, an acid and a first solvent to obtain an electrolyte containing tin and antimony;

[0019] 2) Use a titanium substrate as the cathode, place it in the electrolyte containing tin and antimony obtained in step 1) for electrodeposition to obtain a titanium electrode with co-deposited Sn and Sb, and then after calcination, obtain an electrode with an Sb - SnO2 intermediate layer formed;

[0020] 3) Mix a fluorine source, a tin source and a second solvent to obtain a solution, then immerse the electrode with an Sb - SnO2 intermediate layer formed in step 2) in the solution, and then take it out and perform heat treatment to obtain the anode electrode.

[0021] Preferably, the tin source includes tin tetrachloride;

[0022] The antimony source includes antimony trichloride;

[0023] The acid includes nitric acid;

[0024] The first solvent includes ethylene glycol;

[0025] The molar ratio of the tin source to the antimony source, calculated based on the number of moles of tin and antimony, is 1:(0.1 - 0.4);

[0026] The molar ratio of the tin source to the acid is 1:(0.1 - 0.2);

[0027] In step 1), the mixing time is 2 - 6 hours.

[0028] Preferably, in the electrodeposition, the current density applied to the cathode is 10 - 20 mA / cm 2 ;

[0029] The electrodeposition time is 0.5 - 1 hour;

[0030] The calcination is specifically carried out in an air atmosphere;

[0031] The heating rate of the calcination is 3 - 10 °C / min;

[0032] The constant temperature time of the calcination is 0.5 - 1 hour;

[0033] The constant temperature for calcination is 500 - 550 °C.

[0034] Preferably, the fluorine source includes sodium fluoride and / or potassium fluoride;

[0035] The tin source includes tin tetrachloride;

[0036] The second solvent includes isopropyl alcohol;

[0037] The molar ratio of the tin source to the fluorine source, based on the number of moles of tin and fluorine, is 1:(0.05 - 0.2);

[0038] The heat treatment is specifically carried out in an air atmosphere.

[0039] Preferably, the heating rate of the heat treatment is 3 - 10 °C / min;

[0040] The constant temperature time of the heat treatment is 0.5 - 1 hour;

[0041] The constant temperature for the heat treatment is 500 - 550 °C;

[0042] The impregnation and heat treatment are specifically carried out by repeating the impregnation and heat treatment multiple times;

[0043] The number of times of repeating multiple times is 10 - 20 times.

[0044] The present invention also provides a method for electrochemically oxidizing and degrading organic pollutants, including the following steps:

[0045] Provide an anode electrode, use a platinum sheet as the cathode, and conduct an electrochemical oxidation reaction in an electrolytic solution containing organic pollutants;

[0046] The anode electrode includes the anode electrode described in any one of the above technical solutions or the anode electrode prepared by the preparation method described in any one of the above technical solutions.

[0047] Preferably, the electrolytic solution containing organic pollutants uses a sodium sulfate solution as the background solution;

[0048] The concentration of the organic pollutants is 10 - 50 mg / L;

[0049] The organic pollutants include one or more of bisphenol A, sulfamethoxazole, phenol, and tetracycline hydrochloride;

[0050] The constant potential of the electrochemical oxidation reaction is +2.2 - +2.5 V;

[0051] The time of the electrochemical oxidation reaction is 10 - 60 minutes.

[0052] The present invention provides an anode electrode, which comprises a titanium substrate, an Sb-SnO2 intermediate layer composite on the titanium substrate, and an SnO x F y active layer; wherein, 0 < x < 2 and 0 < y < 4. Compared with the prior art, the anode electrodes prepared by the prior art usually need to use a binder. However, the insulating binder will reduce the electron conductivity and the effective active area of the electrocatalyst, thus limiting the reaction rate in the electrocatalytic reaction process and the deficiencies in the electrode morphology and structure. The present invention believes through research that the three-dimensional porous electrode can provide more active sites and shorten the mass transfer path due to its high specific surface area and through-hole channels. At the same time, the performance of the SnO2 anode is further improved through element doping and structure design. For example, doping SnO2 with an element having a higher electronegativity (such as fluorine) is expected to regulate the surface oxidation reaction to improve the generation efficiency of ·OH free radicals and reduce the reaction energy consumption, thereby significantly improving the efficiency of electrochemical oxidation.

[0053] Based on this, the present invention creatively designs a three-dimensional monolithic electrode material with a specific structure, which is a three-dimensional monolithic electrode based on the synergistic effect of a three-dimensional structure, the construction of an intermediate transition layer, and fluorine element doping. The present invention also provides a corresponding preparation method thereof and the application of the electrode in the electrochemical oxidation degradation of organic pollutants. By introducing an Sb-doped SnO2 intermediate layer between the titanium substrate and the catalytic active layer, the present invention enables the active layer to be tightly combined with the titanium foam substrate, avoiding the use of an insulating binder, thereby ensuring that more active sites can be exposed during the reaction process. At the same time, by introducing fluorine elements into the SnO2 material for doping, the ability of the SnO2 material to generate ·OH free radicals through single-electron water oxidation is improved, thereby further improving the catalytic activity of the electrode and reducing the energy consumption of the electrochemical reaction. The three-dimensional monolithic electrode prepared by the present invention has the advantages of high pollutant removal efficiency, good cyclic use stability, and little influence of the catalytic performance by water quality conditions. The method for preparing the three-dimensional monolithic electrode of the present invention is simple and easy to master. At the same time, the materials required during the synthesis process are non-precious metals that are non-toxic and stable, and the cost is low. Conducting cyclic / repeated electrochemical oxidation degradation of organic pollutants experiments on the prepared three-dimensional monolithic electrode shows that its performance does not decrease significantly, indicating that it has stable catalytic performance, which conforms to the concept of green economy and sustainable development.

[0054] The present invention also provides a preparation method of the three-dimensional monolithic electrode and its application in the electrochemical oxidation degradation of organic pollutants. Using titanium foam as the substrate, through a process combining electrodeposition and impregnation-calcination, an Sb-SnO2 intermediate layer and an SnO x F y active layer are sequentially formed on the surface of the titanium foam, and finally the three-dimensional monolithic electrode is prepared. The present invention in-situ synthesizes the active layer as SnO through an electrodeposition-coupled brushing methodx F y The foam titanium electrode of the load makes good use of the function of the intermediate layer Sb-SnO2 to tightly combine the active layer with the foam titanium substrate. By enhancing the bonding force between the active layer and the substrate through the intermediate layer, the use of adhesives is effectively avoided, the stability of the electrode is improved, more active sites of the catalyst are exposed, the catalytic activity is enhanced, and the electrochemical performance of the three-dimensional integral electrode is improved.

[0055] The experimental results show that when this electrode is applied to the electrochemical oxidation and degradation of organic pollutants, at a constant potential of +2.2V, the removal rate of organic pollutants with an initial concentration of 10mg / L can reach more than 98% within 60 minutes, and its catalytic oxidation performance shows no obvious attenuation after 12 cycles of use. Brief Description of the Drawings

[0056] Figure 1 It is a schematic flow chart of the preparation of the three-dimensional integral electrode provided by the present invention and its application for removing organic pollutants in water;

[0057] Figure 2 It is the X-ray diffraction (XRD) pattern of the SnO x F y active layer catalyst of the three-dimensional integral electrode prepared in the embodiment of the present invention;

[0058] Figure 3 It is the scanning electron microscope (SEM) photograph of the surface (SnO x F y active layer) of the three-dimensional integral electrode prepared in the embodiment of the present invention;

[0059] Figure 4 It is the high-resolution transmission electron microscope (HRTEM) image of the SnO x F y active layer catalyst of the three-dimensional integral electrode prepared in the embodiment of the present invention;

[0060] Figure 5 It is a schematic structural diagram of the electrochemical oxidation reaction device provided by the present invention;

[0061] Figure 6 It is a curve graph showing the change of the removal rate of organic pollutants with time during the electrochemical oxidation and degradation of bisphenol A by the three-dimensional integral electrode prepared in the embodiment of the present invention;

[0062] Figure 7 It is a curve graph of the removal rate of the three-dimensional integral electrode prepared in the embodiment of the present invention for the electrochemical oxidation and degradation of sulfamethoxazole under different solution pH conditions;

[0063] Figure 8Graph of the removal rate of bisphenol A during 12 cycles of the three-dimensional monolithic electrode prepared in the embodiment of the present invention and the dissolution concentration of Sn ions in the solution after the end of the 1st, 5th, and 10th cycle experiments. Detailed implementation manners

[0064] To further understand the present invention, the preferred implementation manners of the present invention will be described below in conjunction with embodiments. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the claims of the present invention.

[0065] For all raw materials of the present invention, there is no particular limitation on their sources, and they can be purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0066] For the raw materials used in the present invention, there is no particular limitation on their purity, and the purity requirements of the raw materials for preparing the electrochemical anode electrode material well-known to those skilled in the art can be used.

[0067] The present invention provides an anode electrode, which includes a titanium substrate, an Sb-SnO2 intermediate layer composite on the titanium substrate, and an SnO x F y active layer;

[0068] Among them, 0 < x < 2, 0 < y < 4.

[0069] In the present invention, the x can be 0.2 to 1.8, can also be 0.5 to 1.5, and can also be 0.7 to 1.2. Specifically, it can be 1.

[0070] In the present invention, the y can be 0.5 to 3.5, can also be 1 to 3, and can also be 1.5 to 2.5. Specifically, it can be 2.

[0071] In the present invention, the anode electrode is preferably a three-dimensional monolithic electrode.

[0072] In the present invention, the thickness of the Sb-SnO2 intermediate layer is preferably 80 to 120 μm, more preferably 88 to 112 μm, and even more preferably 96 to 104 μm.

[0073] In the present invention, the SnO x F y The thickness of the active layer is preferably 10 to 20 μm, more preferably 12 to 18 μm, and even more preferably 14 to 16 μm.

[0074] In the present invention, the titanium substrate is preferably selected from at least one of titanium foam, titanium felt, and titanium sheet.

[0075] In the present invention, in the anode electrode, the mass fraction of Sb-SnO2 is preferably 25% to 45%, more preferably 29% to 41%, and even more preferably 33% to 37%.

[0076] In the present invention, in the anode electrode, SnO x F y The mass fraction of is preferably 10% to 15%, more preferably 11% to 14%, and even more preferably 12% to 13%.

[0077] In the present invention, the anode electrode is specifically preferably an anode electrode for electrochemically oxidizing and degrading organic pollutants.

[0078] The present invention provides a method for preparing an anode electrode, comprising the following steps:

[0079] 1) Mix a tin source, an antimony source, an acid, and a first solvent to obtain an electrolyte containing tin and antimony;

[0080] 2) Use a titanium substrate as the cathode and place it in the electrolyte containing tin and antimony obtained in step 1) for electrodeposition to obtain a titanium electrode with co-deposited Sn and Sb, and then after calcination, obtain an electrode with an Sb-SnO2 intermediate layer formed;

[0081] 3) Mix a fluorine source, a tin source, and a second solvent to obtain a solution, then immerse the electrode with the Sb-SnO2 intermediate layer formed in step 2) in the solution, and then take it out and perform heat treatment to obtain the anode electrode.

[0082] In the present invention, first, a tin source, an antimony source, an acid, and a first solvent are mixed to obtain an electrolyte containing tin and antimony.

[0083] In the present invention, the tin source preferably includes tin tetrachloride.

[0084] In the present invention, the antimony source preferably includes antimony trichloride.

[0085] In the present invention, the acid preferably includes nitric acid.

[0086] In the present invention, the first solvent preferably includes ethylene glycol.

[0087] In the present invention, for the tin source and the antimony source, in terms of the molar amounts of tin and antimony, the molar ratio of the two is preferably 1:(0.1 to 0.4), more preferably 1:(0.15 to 0.35), and even more preferably 1:(0.2 to 0.3), and specifically can be 1:0.2.

[0088] In the present invention, the molar ratio of the tin source to the acid is preferably 1:(0.1 to 0.2), more preferably 1:(0.1 to 0.16), and even more preferably 1:(0.1 to 0.12), and specifically can be 1:0.1.

[0089] In the present invention, in the step 1), the mixing time is preferably 2 - 6 hours, more preferably 2.5 - 5.5 hours, still more preferably 3 - 5 hours, even more preferably 3.5 - 4.5 hours, and specifically may be 4 hours.

[0090] The present invention then uses a titanium substrate as the cathode and places it in the electrolyte containing tin and antimony obtained in the above step for electrodeposition to obtain a titanium electrode with co - deposited Sn and Sb. After calcination, an electrode with an Sb - SnO2 intermediate layer formed is obtained.

[0091] In the present invention, in the electrodeposition, the current density applied to the cathode is preferably 10 - 20 mA / cm 2 , more preferably 12 - 18 mA / cm 2 , still more preferably 14 - 16 mA / cm 2 , and specifically may be 15 mA / cm 2 .

[0092] In the present invention, the electrodeposition time is preferably 0.5 - 1 hour, more preferably 0.7 - 1 hour, still more preferably 0.9 - 1 hour, and specifically may be 1 hour.

[0093] In the present invention, the calcination is specifically preferably carried out in an air atmosphere.

[0094] In the present invention, the heating rate of the calcination is preferably 3 - 10 °C / min, more preferably 5 - 8 °C / min, still more preferably 5 - 6 °C / min, and specifically may be 5 °C / min.

[0095] In the present invention, the holding time of the calcination is preferably 0.5 - 1 hour, more preferably 0.7 - 1 hour, still more preferably 0.9 - 1 hour, and specifically may be 1 hour.

[0096] In the present invention, the holding temperature of the calcination is preferably 500 - 550 °C, more preferably 500 - 530 °C, still more preferably 500 - 520 °C, and specifically may be 500 °C.

[0097] Finally, in the present invention, a fluorine source, a tin source and a second solvent are mixed to obtain a solution. Then, the electrode with an Sb - SnO2 intermediate layer obtained in the above step is impregnated in the solution, and after taking it out, heat treatment is carried out to obtain an anode electrode.

[0098] In the present invention, the fluorine source preferably includes sodium fluoride and / or potassium fluoride, more preferably sodium fluoride or potassium fluoride.

[0099] In the present invention, the tin source preferably includes tin tetrachloride.

[0100] In the present invention, the second solvent preferably includes isopropanol;

[0101] In the present invention, the molar ratio of the tin source to the fluorine source, based on the number of moles of tin and fluorine, is preferably 1:(0.05 - 0.2), more preferably 1:(0.08 - 0.17), still more preferably 1:(0.11 - 0.14), and specifically may be 1:0.1.

[0102] In the present invention, the heat treatment is specifically preferably carried out in an air atmosphere.

[0103] In the present invention, the heating rate of the heat treatment is preferably 3 - 10 °C / min, more preferably 5 - 8 °C / min, still more preferably 5 - 7 °C / min, and specifically may be 5 °C / min.

[0104] In the present invention, the holding time of the heat treatment is preferably 0.5 - 1 hour, more preferably 0.5 - 0.8 hour, still more preferably 0.5 - 0.6 hour, and specifically may be 0.5 hour.

[0105] In the present invention, the holding temperature of the heat treatment is preferably 500 - 550 °C, more preferably 500 - 530 °C, still more preferably 500 - 520 °C, and specifically may be 500 °C.

[0106] In the present invention, the impregnation and heat treatment are specifically preferably carried out by repeating the impregnation and heat treatment multiple times.

[0107] In the present invention, the number of times of repeating multiple times is preferably 10 - 20 times, more preferably 11 - 16 times, still more preferably 11 - 14 times, and specifically may be 11 times.

[0108] The present invention provides a method for electrochemically oxidizing and degrading organic pollutants, comprising the following steps:

[0109] Providing an anode electrode, using a platinum sheet as the cathode, and carrying out an electrochemical oxidation reaction in an electrolyte solution containing organic pollutants;

[0110] The anode electrode includes the anode electrode described in any one of the above technical solutions or the anode electrode prepared by the preparation method described in any one of the above technical solutions.

[0111] The method for electrochemically oxidizing and degrading organic pollutants in the present invention, that is, the application of the anode electrode in electrochemically oxidizing and degrading organic pollutants.

[0112] In the present invention, the electrolyte solution containing organic pollutants uses a sodium sulfate solution as the background solution;

[0113] In the present invention, the concentration of the organic pollutant is preferably 10-50 mg / L, more preferably 10-35 mg / L, still more preferably 10-20 mg / L, and specifically may be 10 mg / L.

[0114] In the present invention, the organic pollutant preferably includes one or more of bisphenol A, sulfamethoxazole, phenol, and tetracycline hydrochloride, and more preferably is bisphenol A, sulfamethoxazole, phenol, or tetracycline hydrochloride.

[0115] In the present invention, the constant potential of the electrochemical oxidation reaction is preferably +2.2 to +2.5 V, more preferably +2.2 to +2.4 V, still more preferably +2.2 to +2.3 V, and specifically may be +2.2 V.

[0116] In the present invention, the time of the electrochemical oxidation reaction is preferably 10-60 minutes, more preferably 20-50 minutes, still more preferably 30-60 minutes.

[0117] In order to complete and refine the overall technical solution of the present invention, better ensure the composition, overall three-dimensional structure, and microscopic morphology of the anode electrode, and further improve the electrochemical performance of the electrode material, the above three-dimensional integral electrode and its preparation method, and a method for electrochemically oxidizing and degrading organic pollutants may specifically include the following content:

[0118] A preparation method of a three-dimensional integral electrode for electrochemically oxidizing and degrading organic pollutants includes the following steps:

[0119] (1) Add tin tetrachloride (SnCl4·5H2O), antimony trichloride (SbCl3), and nitric acid (HNO3) into ethylene glycol, and stir at room temperature to obtain a homogeneous electrolyte containing tin and antimony.

[0120] (2) Use titanium foam as the cathode, place it in the electrolyte solution obtained in step (1), and perform electrodeposition under stirring conditions to obtain a titanium foam electrode with co-deposited Sn and Sb.

[0121] (3) After drying the electrode obtained in step (2) in an oven, calcine it in an air atmosphere to form an Sb-SnO2@Tifoam intermediate layer electrode.

[0122] (4) Immerse the electrode obtained in step (3) in an isopropanol solution containing sodium fluoride (NaF) and tin tetrachloride (SnCl4·5H2O), take it out and dry it, and then calcine it in an air atmosphere. Repeat the above impregnation and calcination steps multiple times to obtain an SnO x F y @Tifoam three-dimensional integral electrode.

[0123] Specifically, in step (1), the molar ratio of SnCl4·5H2O, SbCl3, and HNO3 is 1:0.2:0.1. The stirring time is 4 hours.

[0124] Specifically, the electroplating conditions in step (2) are as follows: the cathode applies a current density of 15 mA / cm 2 . The electroplating time is 1 hour.

[0125] Specifically, the specific preparation method of the intermediate layer in step (3) is as follows: after drying at room temperature in an air atmosphere for 10 minutes, it is heated to 500 °C at a heating rate of 5 °C / min and held at a constant temperature for 1 hour.

[0126] Specifically, the molar ratio of SnCl4·5H2O and NaF in step (4) is 1:0.1; after each impregnation, it is dried at room temperature in an air atmosphere for 10 minutes, then heated to 500 °C at a heating rate of 5 °C / min and held at a constant temperature for 0.5 hour; the impregnation-calcination is repeated 10 times; after 10 times of impregnation-calcination, it is heated to 500 °C at a heating rate of 5 °C / min in an air atmosphere and held at a constant temperature for 1 hour.

[0127] The present invention also provides a method for electrochemically oxidizing and degrading organic pollutants, comprising the following steps:

[0128] A. Prepare a SnO x F y @Ti foam three-dimensional integral electrode;

[0129] B. Using the SnO x F y @Ti foam three-dimensional integral electrode as the anode and a platinum sheet as the cathode, perform an electrochemical oxidation reaction in an electrolyte containing organic pollutants.

[0130] Specifically, the electrolyte containing organic pollutants uses a 0.1 mol / L sodium sulfate solution as the background solution.

[0131] Specifically, the concentration of the organic pollutants is 10 mg / L.

[0132] Specifically, the constant potential of the electrochemical oxidation reaction is +2.2 V, and the time of the electrochemical oxidation reaction is 10 to 60 minutes.

[0133] The method for preparing the three-dimensional integral electrode of the present invention is simple and easy to master. At the same time, the materials required in the synthesis process are non-noble metals that are non-toxic and stable, and the cost is low. Performing cyclic / repeated electrochemically oxidizing and degrading organic pollutants experiments on the prepared three-dimensional integral electrode, its performance does not decrease significantly, indicating that it has stable catalytic performance, meeting the concepts of green economy and sustainable development.

[0134] SeeFigure 1 , Figure 1 It is a schematic flow diagram of the preparation of the three-dimensional monolithic electrode provided by the present invention and its application for removing organic pollutants in water.

[0135] The above content of the present invention provides a three-dimensional monolithic electrode and its preparation method, and a method for electrochemically oxidizing and degrading organic pollutants. The three-dimensional monolithic electrode designed by the present invention is based on the synergistic effects of three-dimensional structure, intermediate transition layer construction and fluorine element doping. The present invention also provides a corresponding preparation method thereof and the application of the electrode in electrochemically oxidizing and degrading organic pollutants. By introducing an Sb-doped SnO2 intermediate layer between the titanium substrate and the catalytic active layer, the active layer is tightly bonded to the titanium foam substrate, avoiding the use of insulating binders, so as to ensure that more active sites of the catalyst can be exposed during the reaction process. At the same time, by introducing fluorine elements into the SnO2 material for doping, its ability to generate ·OH free radicals through single-electron water oxidation is improved, thereby further enhancing the catalytic activity of the electrode and reducing the energy consumption of the electrochemical reaction. The three-dimensional monolithic electrode prepared by the present invention has the advantages of high pollutant removal efficiency, good stability in cyclic use and little influence of catalytic performance by water quality conditions. The method for preparing the three-dimensional monolithic electrode of the present invention is simple and easy to operate. At the same time, the materials required in the synthesis process are non-noble metals that are non-toxic and stable, and the cost is low. The prepared three-dimensional monolithic electrode is subjected to cyclic / repeated electrochemically oxidizing and degrading organic pollutants experiments, and its performance does not decrease significantly, indicating that it has stable catalytic performance, meeting the concepts of green economy and sustainable development.

[0136] The present invention also provides a preparation method of a three-dimensional monolithic electrode and its application in electrochemically oxidizing and degrading organic pollutants. Using titanium foam as the substrate, through a process combining electrodeposition and impregnation-calcination, an Sb-SnO2 intermediate layer and SnO x F y active layer are successively formed on the surface of the titanium foam, and finally a three-dimensional monolithic electrode is obtained. The present invention in-situ synthesizes an active layer of SnO x F y loaded titanium foam electrode by an electrodeposition-coupled brush coating method, and cleverly utilizes the role of the intermediate layer Sb-SnO2 to tightly bond the active layer to the titanium foam substrate. By enhancing the binding force between the active layer and the substrate through the intermediate layer, the use of binders is effectively avoided, the stability of the electrode is improved, more active sites of the catalyst are promoted to be exposed, the catalytic activity is enhanced, and the electrochemical performance of the three-dimensional monolithic electrode is improved.

[0137] Experimental results show that when this electrode is applied to electrochemically oxidize and degrade organic pollutants, at a constant potential of +2.2 V, the removal rate of organic pollutants with an initial concentration of 10 mg / L can reach more than 98% within 60 minutes, and its catalytic oxidation performance shows no obvious attenuation after 12 cycles of use.

[0138] To further illustrate the present invention, the following provides a detailed description of an anode electrode and its preparation method, as well as a method for electrochemically oxidizing and degrading organic pollutants according to the present invention in combination with embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical solution of the present invention, providing detailed implementation manners and specific operation processes, only to further illustrate the features and advantages of the present invention, rather than a limitation on the claims of the present invention. The protection scope of the present invention is not limited to the following embodiments either.

[0139] Example 1

[0140] Preparation of three-dimensional integral electrode

[0141] Dissolve SnCl4·5H2O, SbCl3 and HNO3 in ethylene glycol at a molar ratio of 1:0.2:0.1, and stir at room temperature for 4 hours to obtain a homogeneous electrolyte containing tin and antimony.

[0142] Using titanium foam as the cathode, apply a current density of 15 mA / cm 2 in the above electrolyte for electroplating for 1 hour to obtain a titanium foam electrode with co-deposited Sn and Sb.

[0143] Place the obtained electrode in an oven for drying, then heat it to 500 °C at a rate of 5 °C / min in an air atmosphere and calcine for 1 hour to form an Sb-SnO2@Ti foam intermediate layer.

[0144] Subsequently, immerse the electrode with the intermediate layer in an isopropanol solution prepared from SnCl4·5H2O and NaF (molar ratio 1:0.1), take it out and dry it, then calcine it at 500 °C in an air atmosphere for 0.5 hour. Repeat this impregnation and calcination operation 10 times to finally obtain the SnO x F y @Ti foam three-dimensional integral electrode.

[0145] See Figure 2 , Figure 2 for the X-ray diffraction (XRD) pattern of the active layer catalyst of the three-dimensional integral electrode SnO x F y prepared in the embodiment of the present invention.

[0146] See Figure 3 , Figure 3 for the scanning electron microscope (SEM) photograph of the surface (SnO x F y active layer) of the three-dimensional integral electrode prepared in the embodiment of the present invention.

[0147] Figure 3 It can be seen from x Fy The material presents a two-dimensional nanoparticle packing structure and grows uniformly on the titanium foam skeleton.

[0148] See Figure 4 , Figure 4 which is the high-resolution transmission electron microscopy (HRTEM) image of the three-dimensional monolithic electrode SnO x F y active layer catalyst prepared in the embodiment of the present invention.

[0149] Figure 4 It can be seen from x F y that the main exposed crystal plane of the material is the {110} crystal plane.

[0150] Example 2

[0151] Application of the three-dimensional monolithic electrode in the electrochemical oxidation degradation of bisphenol A

[0152] The three-dimensional monolithic electrode prepared in Example 1 was placed in a 0.1 M Na2SO4 solution containing 10 mg / L bisphenol A.

[0153] Using this SnO x F y @Ti foam three-dimensional monolithic electrode as the anode, a platinum metal sheet as the cathode, and silver / silver chloride as the reference electrode, a constant potential of +2.2 V was applied, and the reaction was stirred at 500 rpm for 10 - 60 minutes.

[0154] See Figure 5 , Figure 5 which is the schematic structural diagram of the electrochemical oxidation reaction device provided by the present invention.

[0155] See Figure 6 , Figure 6 which is the curve graph of the removal rate of organic pollutants varying with time during the electrochemical oxidation degradation of bisphenol A by the three-dimensional monolithic electrode prepared in the embodiment of the present invention. Among them, the concentration of sodium sulfate is 0.1 mol / L, and the initial concentration of bisphenol A is 10 mg / L.

[0156] Figure 6 The curve of the removal rate of bisphenol A in the solution varying with time during the 30-minute reaction in

[0157] Example 3

[0158] Application of the three-dimensional monolithic electrode in the electrochemical oxidation degradation of sulfamethoxazole under different pH conditions

[0159] The three-dimensional monolithic electrode prepared in Example 1 was placed in a 0.1 M Na2SO4 solution containing 10 mg / L sulfamethoxazole. Using this SnO x F y @Tifoam three-dimensional monolithic electrode as the anode, a platinum metal sheet as the cathode, and silver / silver chloride as the reference electrode, an external constant potential of +2.2 V was applied, and the reaction was stirred at 500 rpm for 60 minutes. The initial pH of the reaction solution was adjusted to 1, 3, 5, 7, 9, and 11 respectively with 1 M H2SO4 and 2 M NaOH solutions. The reaction results are shown in Figure 7 , Figure 7 which is the removal rate curve of the electrochemical oxidative degradation of sulfamethoxazole by the three-dimensional monolithic electrode prepared in the examples of the present invention under different solution pH conditions. Among them, the sodium sulfate concentration is 0.1 mol / L, and the initial concentration of sulfamethoxazole is 10 mg / L.

[0160] Figure 7 It can be seen from the removal rate curve of the degradation of sulfamethoxazole under different pH conditions in this example that when the solution pH = 1, 3, 5, 9, and 11, the removal rate of sulfamethoxazole can reach 100% within 60 minutes; while when the solution pH = 7, the removal rate of sulfamethoxazole is about 98% within 60 minutes.

[0161] Example 4

[0162] Electrochemical oxidation cycle stability test of the three-dimensional monolithic electrode

[0163] The SnO x F y @Ti foam three-dimensional monolithic electrode prepared in Example 1 was placed in a 0.1 M Na2SO4 solution containing 10 mg / L bisphenol A. Using this SnO x F y @Tifoam three-dimensional monolithic electrode as the anode, a platinum metal sheet as the cathode, and silver / silver chloride as the reference electrode, an external constant potential of +2.2 V was applied, and the reaction was stirred at 500 rpm for 60 minutes. The above-mentioned electrochemical degradation reaction was repeated multiple times under the above conditions (reusing the electrode).

[0164] See Figure 8 , Figure 8 which is the bisphenol A removal rate during the 12 - time reuse of the three-dimensional monolithic electrode prepared in the examples of the present invention and the Sn ion dissolution concentration in the solution after the end of the 1st, 5th, and 10th cycle experiments.

[0165] Figure 8 It shows the change in the bisphenol A removal rate with the increase in the number of cycles according to the scheme described in this example, as well as the Sn ion dissolution concentration in the solution after the end of the 1st, 5th, and 10th cycle experiments.

[0166] The results show that in 10 cyclic experiments, the removal rate of bisphenol A reached 100% at the end of the 60-minute reaction. However, with the increase in the number of cycles, the reaction rate decreased slightly. After the 10th cycle, the electrode was calcined at 5 °C / min to 500 °C in an air atmosphere for 1 hour, and then the 11th and 12th cyclic experiments were continued according to the above conditions. The results show that the electrode can recover its initial activity, and the removal rate of bisphenol A in the solution can reach 100% within only 30 min in the 11th and 12th cyclic experiments. In addition, the detection results show that the Sn ion concentrations in the solution after the 1st, 5th, and 10th cycles were 94 μg / L, 68 μg / L, and 54 μg / L, respectively, and the Sn dissolution concentration was lower than 0.1 mg / L (i.e., 0.1 ppm).

[0167] The above results prove that the three-dimensional monolithic electrode provided by the present invention has high catalytic stability and reusable performance.

[0168] The above has introduced in detail a three-dimensional monolithic electrode provided by the present invention, its preparation method, and a method for electrochemically oxidizing and degrading organic pollutants. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. An anode electrode, characterized in that, The anode electrode includes a titanium substrate, an Sb-SnO2 intermediate layer composite on the titanium substrate, and SnO x F y active layer; Among them, 0 < x < 2 and 0 < y < 4.

2. The anode electrode according to claim 1, wherein, The anode electrode is a three-dimensional integral electrode; The thickness of the Sb-SnO2 intermediate layer is 80 - 120 μm; The SnO x F y The thickness of the active layer is 10 to 20 μm; The titanium substrate is selected from at least one of titanium foam, titanium felt, and titanium sheet.

3. The anode electrode according to claim 1, characterized in that, In the anode electrode, the mass fraction of Sb-SnO2 is 25% - 45%; In the anode electrode, the mass fraction of SnO x F y is 10% to 15%; The anode electrode is specifically an anode electrode for electrochemically oxidizing and degrading organic pollutants.

4. A method for preparing an anode electrode, characterized in that, It includes the following steps: 1) Mix a tin source, an antimony source, an acid, and a first solvent to obtain an electrolyte containing tin and antimony; 2) Use the titanium substrate as the cathode, place it in the electrolyte containing tin and antimony obtained in step 1) for electrodeposition to obtain a titanium electrode with co-deposited Sn and Sb, and then after calcination, obtain an electrode with an Sb-SnO2 intermediate layer formed; 3) Mix a fluorine source, a tin source, and a second solvent to obtain a solution, then immerse the electrode with the Sb-SnO2 intermediate layer formed obtained in step 2) in the solution, and then take it out and perform heat treatment to obtain the anode electrode.

5. The preparation method according to claim 4, characterized in that, The tin source includes tin tetrachloride; The antimony source includes antimony trichloride; The acid includes nitric acid; The first solvent includes ethylene glycol; For the tin source and the antimony source, in terms of the molar amounts of tin and antimony, the molar ratio of the two is 1:(0.1 - 0.4); The molar ratio of the tin source to the acid is 1:(0.1 - 0.2); In step 1), the mixing time is 2 - 6 hours.

6. The preparation method according to claim 4, characterized in that, During the electro-deposition, the current density applied to the cathode is 10 to 20 mA / cm 2 ; The electrodeposition time is 0.5 - 1 hour; The calcination is specifically carried out in an air atmosphere; The heating rate of the calcination is 3 - 10 °C / min; The holding time of the calcination is 0.5 - 1 hour; The holding temperature of the calcination is 500 - 550 °C.

7. The preparation method according to claim 4, characterized in that, The fluorine source includes sodium fluoride and / or potassium fluoride; The tin source includes tin tetrachloride; The second solvent includes isopropyl alcohol; For the tin source and the fluorine source, in terms of the molar amounts of tin and fluorine, the molar ratio of the two is 1:(0.05 - 0.2); The heat treatment is specifically carried out in an air atmosphere.

8. The preparation method according to claim 4, characterized in that The heating rate of the heat treatment is 3 - 10 °C / min; The holding time of the heat treatment is 0.5 - 1 hour; The holding temperature of the heat treatment is 500 - 550 °C; The impregnation and heat treatment are specifically carried out by repeating the impregnation and heat treatment multiple times; The number of times of repeating multiple times is 10 - 20 times.

9. A method for electrochemically oxidizing and degrading organic pollutants, characterized in that, It includes the following steps: Provide an anode electrode, use a platinum sheet as the cathode, and carry out an electrochemical oxidation reaction in an electrolyte containing organic pollutants; The anode electrode includes the anode electrode described in any one of claims 1 - 3 or the anode electrode prepared by the preparation method described in any one of claims 4 - 8.

10. The method according to claim 9, wherein The electrolyte containing organic pollutants uses a sodium sulfate solution as the background solution; The concentration of the organic pollutants is 10 - 50 mg / L; The organic pollutants include one or more of bisphenol A, sulfamethoxazole, phenol, and tetracycline hydrochloride; The constant potential of the electrochemical oxidation reaction is +2.2 - +2.5 V; The time of the electrochemical oxidation reaction is 10 - 60 minutes.

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