Preparation method and application of iron-doped tin dioxide electrode for organic wastewater treatment
Iron-doped tin dioxide electrodes were prepared by high-pressure spraying-impregnation method, which solved the problem of easy cracking of SnO2 electrode coating, realized efficient and low-cost organic wastewater treatment, and improved the catalytic activity and stability of the electrode.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING IND POLYTECHNIC COLLEGE
- Filing Date
- 2026-04-27
- Publication Date
- 2026-07-17
AI Technical Summary
Existing doped SnO2 electrodes have structural defects in their fabrication process, which leads to easy cracking of the coating, electrolyte penetration, low degradation efficiency, and high cost, making it difficult to achieve efficient and deep mineralization of organic pollutants.
A high-pressure spray-immersion composite coating process is adopted, which combines organic amine and silicate solution to form a porous iron-doped tin dioxide electrode, thereby improving conductivity and stability, inhibiting coating peeling, and enhancing the uniformity of active components.
The preparation process is simple and low-cost, with long electrode life and high catalytic activity. It can efficiently and deeply mineralize organic pollutants, avoid secondary pollution, and improve the specific surface area and material stability.
Smart Images
Figure CN122403579A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of environmental protection and electrochemical materials technology, specifically to a method for preparing and applying an iron-doped tin dioxide electrode for organic wastewater treatment. Background Technology
[0002] With rapid industrialization and urbanization, wastewater discharged from industries such as chemical, pharmaceutical, and dyeing industries contains large amounts of structurally stable, highly toxic, and recalcitrant organic pollutants. For this type of highly toxic organic wastewater, advanced electrochemical oxidation (EAOPs) can be used to completely mineralize the organic pollutants. This involves breaking the chemical bonds of organic matter through strong oxidation by free radicals, deeply degrading it into non-toxic small-molecule intermediates, carbon dioxide, and water, thereby completely eliminating environmental toxicity. In electrocatalytic oxidation technology, the performance of the anode material directly determines the degradation efficiency of organic pollutants and the system operating cost. Currently, commonly used anode materials still have certain limitations. For example, while RuO2 / Ti and IrO2 / Ti electrodes have good conductivity, they have low oxygen evolution potentials and are prone to oxygen evolution side reactions; PbO2 electrodes have high oxidation capacity, but there is a risk of lead leaching leading to secondary pollution; BDD electrodes have excellent performance, but their preparation cost is high, limiting industrialization. In contrast, SnO2-based electrodes combine the advantages of high oxygen evolution potential and relatively low cost, showing promising application prospects. However, pure SnO2 has poor intrinsic conductivity, and its electrocatalytic oxidation typically relies on the free radical pathway in the bulk solution phase. But bulk radicals have extremely short lifetimes and are easily quenched by water impurities, resulting in low actual mineralization efficiency of pollutants. Therefore, it is necessary to modify the oxidation pathway through appropriate non-free radical enhancement to improve the conversion efficiency of organic pollutants. The introduction of Fe not only solves the conductivity problem but also fundamentally regulates the degradation mechanism of pollutants. Studies have shown that smaller radius Fe³⁺… + Replace Sn 4+ Upon entering the rutile lattice, to maintain charge balance, a high concentration of oxygen vacancies (defect states) is induced on the coating surface. These high-concentration oxygen vacancies serve as key active sites, successfully transforming the degradation mechanism of the system from inefficient "bulk radical oxidation" to a "non-radical direct electron transfer (DET)" and "near-interface radical strong oxidation" process dominated by the anode surface. This non-radical / near-interface oxidation process controlled by the electrode surface exhibits extremely strong anti-interference capabilities, enabling more efficient disruption of the molecular skeleton of organic matter, deeply pyrolyzing and mineralizing it into small molecules, and significantly improving the removal rate of chemical oxygen demand (COD).
[0003] However, existing doped SnO2 electrodes still face fatal structural defects in their fabrication process. Due to the significant difference in thermal expansion coefficients between the SnO2 coating and the titanium (Ti) substrate, traditional thermal decomposition methods such as brush coating or single immersion easily lead to severe "mud cracks" (crazing) and porosity in the coating during solvent evaporation and annealing. This loose and agglomerated microstructure not only reduces the effective electrochemical active area but also allows the electrolyte to penetrate along the cracks to the underlying titanium substrate under a strong electric field, oxidizing and forming an insulating TiO2 passivation layer. The passivation layer causes a sharp increase in charge transfer resistance, coating detachment, and ultimately rapid electrode deactivation. Therefore, there is an urgent need in this field to develop a novel and environmentally friendly electrode fabrication process. Through synergistic innovation in process technology and precursor formulation, we can fully leverage the chemical advantages of Fe doping, namely "non-radical direct electron transfer" and "efficient mineralization," while also completely eliminating the "mud crack" defect in the coating from a physical microstructure perspective and cutting off the electrolyte's penetration path. This will result in a long-lasting wastewater treatment anode that is highly active, non-toxic, deeply mineralized, and has a long passivation resistance life. Summary of the Invention
[0004] I. Technical problems to be solved To address the shortcomings of existing technologies, this invention proposes a method for preparing iron-doped tin dioxide electrodes for organic wastewater treatment, which achieves deep mineralization by adjusting the ratio of free radicals to non-free radicals.
[0005] II. Specific Technical Solutions A method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment includes the following steps: Step 1: Boil the titanium mesh in a sodium hydroxide solution to remove the oil stains on the surface of the titanium mesh substrate; Step 2: Place the titanium mesh in a saturated weak acid solution and etch it until a rough surface is formed; Step 3: Mix the organic amine, tin source, and silicate solution, and stir until the solution is homogeneous to obtain the first precursor; Step 4: Dissolve the iron source and silicate solution in deionized water, stir and mix evenly, and set aside to obtain the second precursor; Step 5: The first precursor is evenly sprayed onto the titanium mesh from Step 2 using a spray gun and then baked in a furnace. Step 6: Repeat step 5 until a tin dioxide layer is formed on the titanium mesh for later use; Step 7: Immerse the titanium mesh from Step 6 into the second precursor, remove it, and then calcine it in a furnace. Step 8: Repeat Step 7 1-2 times, place it in the furnace for baking, then remove and cool to obtain the electrode.
[0006] Preferably, in step one, the concentration of sodium hydroxide is 0.1-0.5 mol / L.
[0007] Preferably, in step three, the silicate solution is a 34% silicate solution, and the mass ratio of the organic amine, tin source and 34% silicate solution is 90-120:185-300:25-50.
[0008] As a preferred embodiment, in step four, the ratio of the iron source, silicate solution, and deionized water is 2-12:8-20:1000 by mass.
[0009] Preferably, in steps five and seven, the pressure of the spray gun is 5-10 MPa, the temperature in the furnace is 400-650℃, and the roasting time is 15-20 minutes.
[0010] As a preferred option, step eight specifically involves placing the vessel in a furnace at 400-650°C for 1-5 hours after the final impregnation.
[0011] Preferably, the weak acid solution is a weak acid that can coordinate with titanium, including oxalic acid or hydrofluoric acid.
[0012] Preferably, the organic amine is triethanolamine, diethanolamine, or ethylenediamine; and the iron source is ferric chloride hexahydrate, anhydrous ferric chloride, ferric nitrate nonahydrate, ferrous chloride tetrahydrate, or ferric sulfate.
[0013] An application of an iron-doped tin dioxide electrode for treating organic wastewater, using the iron-doped tin dioxide electrode as the anode and a pure titanium mesh as the cathode to treat organic pollutants in the water.
[0014] The beneficial effects of this invention are: simple preparation process, low cost, long lifespan, and high catalytic activity. Because silicates are used in the preparation process, the coating peeling problem caused by excessive expansion of organic amines during heating is suppressed. Simultaneously, the pore-forming effect of organic amines results in a large electrode specific surface area and stable electrocatalytic activity. In wastewater treatment, toxic organic matter can be degraded into smaller organic molecules and non-toxic inorganic substances through catalysis and oxidation, breaking their chemical bonds and preventing secondary pollution of water bodies.
[0015] Using organic amines as a solvent generates a porous structure during thermal decomposition, which increases the specific surface area of the electrode. At the same time, the generated carbon improves the conductivity of the material.
[0016] Using a small amount of silicate has several advantages. First, it inhibits the formation of pores in organic matter, preventing the material from easily detaching due to excessively large pore sizes. Second, the amount of SiO2 produced during thermal decomposition is minimal and does not affect the material's conductivity. Third, it helps improve the stability of the electrode coating. A small amount of silicate solution can penetrate into the electrode gaps and pores, and the solidified silica gel can block capillary channels, increasing the material's density and strength, and enhancing the stability of the electrode surface.
[0017] Compared with the traditional single "immersion-lifting method" or brush coating process, the present invention adopts a "high pressure spraying-immersion method" composite coating process, which makes the bottom layer more firmly and densely bonded and the surface active components more uniformly doped. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation
[0019] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.
[0020] like Figure 1 The following is a method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment and its application: The specific steps are as follows: S1: Place the titanium mesh in a 0.1-0.5 mol / L sodium hydroxide solution and boil until it just boils to remove the oil stains on the surface of the titanium mesh substrate. Then place the degreased titanium mesh in a saturated weak acid solution to etch until the surface forms a rough texture. S2: Mix the organic amine, tin source and 34% silicate solution, and stir thoroughly until the solution is uniformly mixed to obtain precursor 1. The organic amine, tin source and 34% silicate solution are in the mass ratio of (90-120):(185-300):(25-50). S3: Dissolve the iron source and 34% silicate solution in deionized water, mix thoroughly and stir well before use to obtain precursor 2. The iron source, 34% silicate solution and deionized water are calculated by mass ratio as (2-12):(8-20):1000. S4: The precursor 1 in S2 is uniformly sprayed onto the titanium mesh treated in S1 using a high-pressure spray gun at 5-10 MPa, and then calcined in a muffle furnace at 400-650℃ for 15-20 minutes. S5: Repeat step S4 2-3 times to form a tin dioxide layer for later use; S6: Immerse the titanium mesh in S5, which has formed a tin dioxide layer, into precursor 2 in S3, and after taking it out, calcine it in a muffle furnace at a temperature of 400-650℃ for 15-20 minutes. S7: Repeat step S6 1-2 times. After the last impregnation, place it in a muffle furnace at 400-650℃ for 1-5 hours, then remove and cool.
[0021] As a further preferred option: The aforementioned weak acids are weak acids such as oxalic acid or hydrofluoric acid that can coordinate with titanium.
[0022] The organic amines mentioned above are triethanolamine, diethanolamine, or ethylenediamine.
[0023] The aforementioned tin source is stannous chloride dihydrate, stannous tetrachloride pentahydrate, or anhydrous stannous tetrachloride.
[0024] The silicate solution mentioned above is a sodium silicate solution, a potassium silicate solution, or a lithium silicate solution.
[0025] The iron sources mentioned above are ferric chloride hexahydrate, anhydrous ferric chloride, ferric nitrate nonahydrate, ferrous chloride tetrahydrate, or ferric sulfate.
[0026] An application of a method for preparing iron-doped tin dioxide electrodes according to the above-mentioned high-pressure spraying-impregnation method is key in that: the iron-doped tin dioxide electrode prepared by the high-pressure spraying-impregnation method is used as the anode, and a pure titanium mesh is used as the cathode to treat organic pollutants in water.
[0027] The advantages of adopting the above technical solution are as follows: (1) Using organic amines as solvents, a porous structure is generated during thermal decomposition, which increases the specific surface area of the electrode. At the same time, the generated carbon improves the conductivity of the material. (2) The amount of silicate used is small, which on the one hand can inhibit the formation of pores in organic matter and avoid the material from falling off easily due to the large pore size; on the other hand, the amount of SiO2 produced during thermal decomposition is very small and does not affect the conductivity of the material; thirdly, it is beneficial to improve the stability of the electrode coating. A small amount of silicate solution can penetrate into the gaps and pores of the electrode, and the solidified silica gel can block the capillary channels, increase the density and strength of the material, and increase the stability of the electrode surface; (3) Compared with the traditional single "immersion-lifting method" or brush coating process, the present invention adopts the "high pressure spraying-immersion method" composite coating process, which makes the bottom layer more firmly and densely bonded and the surface active components more uniformly doped.
[0028] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims.
Claims
1. A method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment, characterized in that, The steps involved include: Step 1: Boil the titanium mesh in a sodium hydroxide solution to remove the oil stains on the surface of the titanium mesh substrate; Step 2: Place the titanium mesh in a saturated weak acid solution and etch it until a rough surface is formed; Step 3: Mix the organic amine, tin source, and silicate solution, and stir until the solution is homogeneous to obtain the first precursor; Step 4: Dissolve the iron source and silicate solution in deionized water, stir and mix evenly, and set aside to obtain the second precursor; Step 5: The first precursor is evenly sprayed onto the titanium mesh from Step 2 using a spray gun and then baked in a furnace. Step 6: Repeat step 5 until a tin dioxide layer is formed on the titanium mesh for later use; Step 7: Immerse the titanium mesh from Step 6 into the second precursor, remove it, and then calcine it in a furnace. Step 8: Repeat Step 7 1-2 times, place it in the furnace for baking, then remove and cool to obtain the electrode.
2. The method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment according to claim 1, characterized in that: In step one, the concentration of sodium hydroxide is 0.1-0.5 mol / L.
3. The method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment according to claim 1, characterized in that: In step three, the silicate solution is a 34% silicate solution, and the organic amine, tin source and 34% silicate solution are in a mass ratio of 90-120:185-300:25-50.
4. The method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment according to claim 1, characterized in that: In step four, the ratio of the iron source, silicate solution and deionized water is calculated to be 2-12:8-20:1000 by mass.
5. The method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment according to claim 1, characterized in that: In steps five and seven, the spray gun pressure is 5-10 MPa, the furnace temperature is 400-650℃, and the roasting time is 15-20 minutes.
6. The method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment according to claim 1, characterized in that: Step eight specifically involves placing the vessel in a furnace at 400-650°C for 1-5 hours after the final impregnation.
7. The method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment according to claim 1, characterized in that: The weak acid solution is a weak acid that can coordinate with titanium, including oxalic acid or hydrofluoric acid.
8. The method for preparing an iron-doped tin dioxide electrode for organic wastewater treatment according to claim 1, characterized in that: The organic amine is triethanolamine, diethanolamine, or ethylenediamine; the iron source is ferric chloride hexahydrate, anhydrous ferric chloride, ferric nitrate nonahydrate, ferrous chloride tetrahydrate, or ferric sulfate.
9. The application of the iron-doped tin dioxide electrode for organic wastewater treatment according to any one of claims 1-8, characterized in that: An iron-doped tin dioxide electrode is used as the anode, and a pure titanium mesh is used as the cathode to treat organic pollutants in water.