Sn-zn / ac particle, and preparation method and application thereof

Abstract

The application belongs to the technical field of electrocatalyst materials, and particularly relates to a Sn-Zn / AC particle and a preparation method and application thereof. The Sn-Zn / AC particle is successfully prepared by loading SnO2 and ZnSnO3 on the surface of activated carbon. The uniform distribution of SnO2 and ZnSnO3 on the surface of activated carbon not only improves the stability of the particle, but also prolongs the service life thereof; the introduction of Zn not only improves the densification degree of SnO2, but also effectively reduces the charge transfer resistance of the particle electrode. The excellent charge transfer capacity of SnO2 and ZnSnO3 is combined, which promotes the efficient generation of active free radicals, thereby significantly improving the catalytic degradation removal rate of the organic pollutants by the electrocatalytic system based on the Sn-Zn / AC particle. In addition, the preparation method of the Sn-Zn / AC particle also has many advantages such as simple operation, strong controllability and low energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology. More specifically, it relates to Sn-Zn / AC particles, their preparation method, and their applications. Background Technology

[0002] Statistics show that approximately one million tons of dyes are produced globally each year, with over 15% released into the environment as pollutants in industrial wastewater. Dye wastewater entering the ecosystem can cause mutagenicity, carcinogenicity, and harm to the brain, central nervous system, and reproductive system. Dyes can be classified into reactive dyes, acid dyes, and basic dyes, among others. Basic dyes are also known as cationic dyes. Commonly used cationic dyes include methylene blue, rhodamine B, and Congo red. Methylene blue, a cationic dye widely used in the textile, leather, pharmaceutical, and food industries, is not biologically removable from wastewater, is toxic, carcinogenic, and poses a threat to human health and the environment. To reduce the harm caused by dye wastewater, the main wastewater treatment methods include physical methods, chemical methods, biological methods, and advanced oxidation processes. However, traditional methods such as physical, chemical, and biological methods have long adsorption contact times, resulting in incomplete removal of dye wastewater. Furthermore, these traditional technologies are prone to secondary pollution due to the use of chemicals in the treatment process, and have high removal costs. Advanced oxidation techniques (AOPs) are highly regarded as a novel and reliable method for effectively removing persistent dyes, offering advantages such as rapid, thorough, efficient, and low-pollution reactions.

[0003] Commonly used advanced oxidation technologies include Fenton oxidation, ozone oxidation, wet oxidation, photocatalytic oxidation, electrocatalytic oxidation, three-dimensional electrocatalytic oxidation, and persulfate oxidation. Among these, electrocatalytic oxidation is characterized by its simple operation, environmental friendliness, and mild reaction conditions. Traditional two-dimensional electrochemical processes suffer from drawbacks such as limited pollutant mass transfer, small specific surface area, low current efficiency, high energy consumption, and low removal efficiency. In contrast, three-dimensional electrochemical advanced oxidation processes offer higher specific surface area, greater mass transfer distance, and higher pollutant removal efficiency, and can completely mineralize organic pollutants that are not biologically removable, making them a highly efficient method for treating dye wastewater. The core of three-dimensional electrochemical technology is the particulate electrode. In traditional electrochemical reactors, conductive particles are filled between the cathode and anode. These particles are polarized under the electrostatic field generated by the anode and cathode, forming numerous charged micro-regions on their surfaces. These micro-regions act as tiny electrodes, or "particulate electrodes." These particulate electrodes carry opposite charges at their ends, thus forming numerous third electrodes throughout the reaction system. These particle electrodes can independently perform functions similar to those of traditional electrodes in electrolytic cells, such as promoting electron transfer and accelerating chemical reactions. For example, Pu et al. (Pu Y, Zhao F, Chen Y, et al. Enhanced Electrocatalytic Oxidation of Phenol by SnO2-Sb2O3 / GAC Particle Electrodes in a Three-Dimensional Electrochemical Oxidation System[J]. Water, 2023, 15(10): 1844.) disclosed a SnO2-Sb2O3 / GAC particle electrode, which can remove 99.65% of phenol in 180 min and has good stability. However, the electrocatalytic removal efficiency of the SnO2-Sb2O3 / GAC particle electrode is still relatively slow and cannot meet the removal requirements of rapid treatment. Its electrocatalytic efficiency still needs to be further improved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing particle electrode, which is still slow in catalytic efficiency and cannot meet the needs of rapid treatment of organic pollutants removal, and to provide a Sn-Zn / AC particle.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned Sn-Zn / AC particles.

[0006] Another object of the present invention is to provide an electrocatalytic system based on the Sn-Zn / AC particles described above.

[0007] Another object of the present invention is to provide the application of the above-described Sn-Zn / AC particles or the above-described electrocatalytic system in the degradation and removal of organic pollutants.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] This invention protects a Sn-Zn / AC particle, wherein the Sn-Zn / AC particle is supported by activated carbon and mainly loaded with SnO2 and ZnSnO3.

[0010] The Sn-Zn / AC particles prepared in this invention use activated carbon (AC) as a support, mainly loaded with SnO2 and ZnSnO3. AC exhibits high conductivity, stable chemical properties, and excellent free radical catalytic ability. This support not only loads the active component SnO2 but also contains a small amount of ZnSnO3. SnO2 was chosen due to its high oxygen evolution potential, excellent conductivity, and chemical stability; while the loading of ZnSnO3 not only covers the surface of AC but also penetrates into some of the internal pores, forming an anodic protective layer. This protective layer effectively inhibits Sn... 4+ The dissolution of SnO2 enhances its densification and reduces the charge transfer resistance of the particle electrode, thereby significantly improving the charge transfer efficiency on the Sn-Zn / AC particle surface. Under the influence of an electric field, Sn-Zn / AC particles are more readily polarized to form microelectrodes. The increase in these microelectrodes and their higher oxygen evolution potential effectively suppress the oxygen evolution side reaction during the reaction process, promoting the generation of more hydroxyl radicals (·OH) in the system. Thanks to the synergistic effect of Sn-Zn / AC particles and active free radicals, pollutants can be rapidly removed by electrocatalytic degradation, demonstrating the excellent catalytic activity and stability of Sn-Zn / AC particles.

[0011] This application protects a method for preparing the above-mentioned Sn-Zn / AC particles, comprising the following steps:

[0012] Add activated carbon to Sn 4+ Zn 2+ After being fully impregnated in the impregnation solution, Sn-Zn / AC particles are obtained by fully calcining at 400-650℃.

[0013] This application combines impregnation and calcination methods to prepare Sn-Zn / AC particles, successfully achieving Sn 4+ and Zn 2+ Good loading on the AC surface significantly improves particle performance. The impregnation solution ensures that Sn... 4+ and Zn 2+It can be uniformly loaded on the AC surface; the modified layer formed by calcination not only has better corrosion resistance, but also forms ZnSnO3 with excellent charge transfer ability, which significantly improves the oxygen evolution potential of the prepared Sn-Zn / AC particles, further enhancing the electrocatalytic removal capacity of organic pollutants.

[0014] Preferably, the activated carbon is pretreated activated carbon, and the pretreatment includes water washing, alkali washing, acid washing, and drying. During the pretreatment of activated carbon, water washing removes large particulate impurities and dust adhering to the material surface; alkali washing effectively removes grease and alkali-soluble substances; acid washing further removes any impurities or metal oxide films that may exist on the material surface; and drying brings the material to a suitable state, which is beneficial for subsequent metal loading.

[0015] Furthermore, the activated carbon is preferably activated carbon particles (AC particles). Due to their large specific surface area and abundant pore structure, AC particles are beneficial for the adsorption and enrichment of pollutants, thereby effectively increasing the concentration of pollutant substrates at the particle electrode interface and accelerating the removal process of organic pollutants.

[0016] Furthermore, the AC particles have a mesh size of 1 to 3.

[0017] Furthermore, the pretreatment includes water washing, alkali washing, acid washing, and drying.

[0018] Furthermore, the washing includes soaking and rinsing.

[0019] Furthermore, the soaking involves adding AC particles to water and soaking them.

[0020] Furthermore, the cleaning process involves repeatedly washing the soaked AC particles 3 to 5 times until the aqueous solution is clear and transparent.

[0021] Specifically, the water washing includes soaking AC particles in water and washing them repeatedly 3 to 5 times until the aqueous solution is clear and transparent.

[0022] Furthermore, the alkaline washing includes filtration, stirring, and rinsing.

[0023] Furthermore, the filtration involves filtering the washed AC particles using a sieve.

[0024] Further, the stirring involves adding the filtered AC particles to 2000 mL of a 0.1–1 mol / L sodium hydroxide solution and stirring at 200–500 rpm / min for 10–60 min.

[0025] Furthermore, the rinsing involves repeatedly rinsing the AC particles with water 3 to 5 times after stirring to remove residual alkaline solution.

[0026] Specifically, the alkaline washing includes filtering the water-washed AC particles through a sieve, adding the filtered AC particles to 2000 mL of 0.1–1 mol / L sodium hydroxide solution, stirring at 200–500 rpm / min for 10–60 min, and rinsing repeatedly with water 3–5 times after stirring to remove residual alkaline solution.

[0027] Furthermore, the pickling process includes agitation and rinsing.

[0028] Further, the stirring involves adding the alkali-washed AC particles to 2000 mL of 0.1–1 mol / L hydrochloric acid solution and stirring at 200–500 rpm / min for 10–60 min.

[0029] Furthermore, the rinsing involves repeatedly rinsing the AC particles after stirring with water 3 to 5 times to remove residual acid.

[0030] Specifically, the acid washing includes adding the alkaline-washed AC particles to 2000 mL of 0.1–1 mol / L hydrochloric acid solution, stirring at 200–500 rpm / min for 10–60 min, and rinsing repeatedly with water 3–5 times after stirring to remove residual acid.

[0031] Furthermore, the drying process includes heating the acid-washed AC particles to 30–100°C, drying them for 6–24 hours until constant weight, and then cooling them to obtain the pretreated AC particles.

[0032] Furthermore, the method for preparing the impregnation solution includes the following steps:

[0033] Will contain Sn 4+ Zn 2+ The solution is mixed with citric acid and alcohol solvents to obtain the impregnation solution.

[0034] Furthermore, the Sn 4+ Selected from hydrates of tin chloride, potassium stannate, sodium stannate, or any of the above tin salts.

[0035] Furthermore, the Sn 4+ The concentration is 0.05–0.6 mol / L.

[0036] Furthermore, the Zn 2+ Selected from hydrates of zinc nitrate, zinc sulfate, zinc chloride, or any of the zinc salts mentioned above.

[0037] Furthermore, the Zn 2+ The concentration is 0.05–0.6 mol / L.

[0038] Furthermore, the Sn 4+ With Zn 2+The molar ratio is 1:(0.083~12). This invention achieves precise control of Sn. 4+ Zn 2+ The content and distribution of these elements in the solution better achieve a uniform distribution of these elements on the surface of AC particles.

[0039] Preferably, the Sn 4+ With Zn 2+ The molar ratio of SnO2 to ZnSnO3 is 1:(5–10). Within this range, the synergistic effect of SnO2 and ZnSnO3 is significantly enhanced, thus enabling Sn-Zn / AC particles to efficiently catalyze the removal of organic pollutants. Simultaneously, this synergistic effect promotes the formation of a stable anodic protective layer, effectively inhibiting Sn... 4+ The dissolution of the particles maintains their structural stability and slows down performance degradation.

[0040] Preferably, the Sn 4+ With Zn 2+ The molar ratio is 1:(5-8).

[0041] More preferably, the Sn 4+ With Zn 2+ The molar ratio is 1:6.

[0042] Furthermore, the Sn-containing 4+ Zn 2+ The solvent for the solution includes one or more of ethanol, methanol, and propanol.

[0043] Furthermore, the alcohol solvent includes one or more of ethylene glycol, propylene glycol, and butanediol. Alcohol solvents can react with metal ions (Sn) through functional groups such as hydroxyl groups in their molecular structure. 4+ Zn 2+ This forms a complex, enhancing the stability of metal ions in the solution and preventing premature precipitation, thereby ensuring the concentration and activity of metal ions in the impregnation solution.

[0044] Furthermore, the mass of the pretreated AC particles is 0.5–10 g.

[0045] Furthermore, the volume of the impregnation solution is 0.1 to 0.5 L.

[0046] Furthermore, the method of thorough impregnation includes static soaking and agitation soaking. Thorough impregnation promotes deep penetration of the electrolyte into the particles, ensuring full activation of the material.

[0047] Furthermore, the static soaking refers to soaking for 0.5 to 5 hours under static conditions.

[0048] Furthermore, the conditions for the shaking soaking are shaking at 50–150 rpm / min for 0.5–3 hours.

[0049] Specifically, the thorough soaking includes standing soaking for 0.5 to 5 hours, followed by shaking soaking at 50 to 150 rpm / min for 0.5 to 3 hours.

[0050] Furthermore, the process of fully impregnating also includes drying.

[0051] Furthermore, the drying process includes oil bath heating and vacuum drying.

[0052] Preferably, the oil bath heating conditions are heating at 50–105°C for 0.5–3 hours.

[0053] Preferably, the vacuum drying conditions are drying at 50–105°C for 0.5–5 hours.

[0054] Preferably, the temperature for thorough calcination is 400–600°C. The calcination temperature affects the yield of Sn. 4+ Zn 2+ The microstructure and composition of tin zinc oxide are directly affected. When the temperature is too high (>650℃) or too low (<400℃), this effect may cause the structure of tin zinc oxide to be destroyed, which in turn increases the charge transfer resistance and leads to a decrease in the oxygen evolution potential, ultimately affecting the removal rate of organic pollutants.

[0055] Furthermore, the sufficient roasting time is 1 to 5 hours.

[0056] This invention protects an electrocatalytic system comprising a cathode, an anode, a third electrode, and an electrolyte, wherein the third electrode comprises the Sn-Zn / AC particles obtained above.

[0057] The electrocatalytic system based on Sn-Zn / AC particles prepared in this invention has a large specific surface area and strong adsorption activity. During the electrocatalytic process of this system, various active species with strong oxidizing activity are generated, such as hydroxyl radicals (·OH) and sulfate radicals (SO4). - This electrocatalytic system has advantages such as simple operation, environmental friendliness, mild and rapid reaction conditions, thoroughness, high efficiency, and low pollution.

[0058] Furthermore, the electrocatalytic system also includes an electrolyte, an electrolytic cell, a power supply, and a stirrer. The electrolytic reactor is a cylindrical electrolytic cell with a capacity of 300–600 mL. The positive and negative electrodes are placed perpendicularly to each other in the reactor at a distance of 20–60 mm. The reactor is filled with a certain amount of modified activated carbon particles in a fluidized state, which move freely under the action of a magnetic rotor. The reactor is connected to a DC regulated power supply using electrode clamps and a power cord connection device. The reactor is placed in a heat-collecting constant-temperature stirring device, and the reaction is carried out at a constant rotation speed at a water temperature of 25–35 °C.

[0059] Furthermore, the positive and negative electrodes are platinum-titanium plated electrodes.

[0060] Furthermore, the electrolyte is Na2SO4 at a concentration of 10–50 mmol / L.

[0061] Furthermore, the voltage of the electrolytic cell is 3 to 7V.

[0062] Furthermore, the power supply is a DC regulated power supply.

[0063] Furthermore, the stirrer is a heat-collecting constant-temperature stirrer.

[0064] Furthermore, the stirring rate of the stirrer is 200–600 rpm / min.

[0065] Furthermore, as a preferred embodiment, the experimental procedure for the electrocatalytic system includes the following steps:

[0066] The effect of Sn-Zn / AC particles on the removal efficiency of dye wastewater was evaluated using the removal rate of methylene blue (MB) as an indicator. MB solid and other necessary reagents were accurately weighed using an electronic balance, dissolved thoroughly in ultrapure water, and the solution was transferred to a 200 mL volumetric flask and brought to volume. Before the experiment, a certain amount of particles was soaked in an MB solution with a concentration of 10–50 mg / L for 0.5–3 h to eliminate the influence of particle electrode adsorption. Initial conditions were set as follows: constant voltage 3–7 V, sodium sulfate concentration 10–50 mmol / L, pH 2–7, particle electrode loading 0.5–3 g, constant rotation speed, and reaction time 30–100 min, including 5–30 min of adsorption without electrolysis and 20–80 min of electrocatalytic reaction. Every 5–20 min, 2–5 mL of liquid water sample was drawn using a syringe, filtered through a 0.22 μm aqueous filter membrane, and transferred to a sample tube. Relevant parameters were set, and the absorbance value of the water sample was measured.

[0067] This invention protects the application of the above-mentioned Sn-Zn / AC particles or the above-mentioned electrocatalytic system in the degradation and removal of organic pollutants.

[0068] The principle of this invention for degrading and removing organic pollutants is as follows: An electrocatalytic system based on Sn-Zn / AC particles degrades and removes MB through a combination of direct and indirect electrooxidation. In the direct electrocatalytic process, Sn-Zn / AC particles form microelectrodes under the influence of an electric field. MB is adsorbed onto the surfaces of the main electrode and the particle microelectrodes under the dual effects of physical adsorption and electroadsorption, and subsequently oxidized and decomposed in the anodic regions of the main electrode and the particle microelectrodes. In the indirect reaction process, driven by voltage and Coulomb force, the anodic regions of the main electrode and the particle microelectrodes exhibit strong oxidizing properties (i.e., electron-withdrawing ability), while the cathode regions exhibit reducing properties (i.e., electron-donating ability). Therefore, the anodic region can degrade water or hydroxide ions (OH-). - The oxidation process generates a large amount of ·OH, while the cathode region can reduce dissolved oxygen to H2O2. This is because ·OH and SO42- in the solution... - • Coexistence, • OH can also promote the formation of small amounts of hydrogen sulfate (HSO4). - ) is converted into SO4 - ·. In ·OH, SO4 - Under the combined action of Mb and H2O2, MB is gradually decomposed into small organic molecules and is eventually mineralized into water and carbon dioxide.

[0069] Furthermore, the organic pollutant is an organic pollutant containing a benzene ring.

[0070] Furthermore, the organic pollutant containing a benzene ring includes one or more of methylene blue, rhodamine B, and methyl orange.

[0071] Preferably, the organic pollutant containing a benzene ring is methylene blue.

[0072] Compared with the prior art, the present invention has the following beneficial effects:

[0073] This invention successfully prepared Sn-Zn / AC particles by loading SnO2 and ZnSnO3 onto the surface of activated carbon. The uniform distribution of SnO2 and ZnSnO3 on the activated carbon surface not only improves particle stability but also extends their lifespan. The introduction of Zn not only enhances the densification of SnO2 but also effectively reduces the charge transfer resistance of the particle electrode. The excellent charge transfer capabilities of SnO2 and ZnSnO3 combined promote the efficient generation of active free radicals, thereby significantly improving the catalytic degradation and removal rate of organic pollutants by the electrocatalytic system based on Sn-Zn / AC particles. Furthermore, the preparation method of Sn-Zn / AC particles also has many advantages such as simple operation, high controllability, and low energy consumption. Attached Figure Description

[0074] Figure 1 This is a flowchart of the preparation of Sn-Zn / AC particles in Example 1.

[0075] Figure 2 The reactor device for applying the Sn-Zn / AC particles prepared in Example 1 to the electrocatalytic system.

[0076] Figure 3 This is an experimental setup for applying the Sn-Zn / AC particles prepared in Example 1 to an electrocatalytic system.

[0077] Figure 4 The images shown are SEM images (a) of the preprocessed AC particles prepared in Example 1, magnified 250 times, and SEM images (b) of the preprocessed AC particles, magnified 1000 times.

[0078] Figure 5 The images shown are SEM images (a) of Sn-Zn / AC particles prepared in Example 1, magnified 250 times, and (b) of Sn-Zn / AC particles, magnified 1000 times.

[0079] Figure 6 The total elemental distribution spectrum (a) of the pretreated AC particles prepared in Example 1 and the total elemental distribution spectrum (b) of the Sn-Zn / AC particles are shown.

[0080] Figure 7 The images show the XRD patterns of the Sn-Zn / AC particles prepared in Example 1 and Comparative Example 3, and the pretreated AC particles.

[0081] Figure 8 The image shows the XRD pattern of the Sn-Zn powder prepared in Comparative Example 5.

[0082] Figure 9 This is a schematic diagram illustrating the catalytic principle of the electrocatalytic system based on Sn-Zn / AC particles in Example 1.

[0083] Figure 10 The graph (a) shows the MB removal rate curves of the electrocatalytic systems constructed in Examples 1, 2 to 5, and 6 to 10 over time, and the graph (b) shows the energy consumption comparison of the electrocatalytic systems in Examples 1, 2 to 4 at a fixed removal rate of 80% MB.

[0084] Figure 11 The graph shows the MB removal rate of the particles prepared in Example 1 and Comparative Example 4 over time in different organic pollutants.

[0085] Figure 12 The EPR detection spectra of the Sn-Zn / AC particles prepared in Example 1 at 5 min (a) and 10 min (b) are shown.

[0086] Figure 13Linear current-voltage curves of the particles prepared in Example 1 and Comparative Example 3.

[0087] Figure 14 The electrochemical impedance spectroscopy of the particles prepared in Example 1 and Comparative Example 3 is shown.

[0088] Figure 15 The image shows the Tafel slope diagrams of the particles prepared in Example 1 and Comparative Example 3.

[0089] Figure 16 The bar chart shows the MB removal rate of the Sn-Zn / AC particles prepared in Example 1 after 5 cycles. Detailed Implementation

[0090] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0091] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0092] Figure 4 (a) indicates Figure 4 Figure (a) in the middle; Figure 4 (b) indicates Figure 4 Figure (b) in the diagram is used as an example; the other figures are named similarly.

[0093] Example 1: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0094] 1. Preparation of Sn-Zn / AC particles

[0095] The preparation process of Sn-Zn / AC particles is shown in the flowchart below. Figure 1 As shown, it specifically includes the following steps:

[0096] S1. Pretreatment of activated carbon (AC) granules: ① Washing with water: Take 10g of granules with a particle size of 2 mesh. ① Place AC granules in a 2000mL beaker, add deionized water to soak and wash repeatedly 3 times until the aqueous solution is visually clear and transparent; ② Alkali washing: Prepare 2000mL of 0.1mol / L sodium hydroxide solution, filter the AC granules washed in step ① through a sieve and add them to the alkaline solution. Stir with an electric stirrer at 250rpm / min for 30min. After stirring, rinse repeatedly with ultrapure water 3 times to remove residual alkaline solution; ③ Acid washing: Prepare 2000mL of 0.1mol / L hydrochloric acid solution, add the granules washed in step ② to the hydrochloric acid solution, stir with an electric stirrer at 250rpm / min for 30min. After stirring, soak with ultrapure water and rinse repeatedly 3 times to remove residual acid; ④ Drying: Place the cleaned AC granules in an electric heating drying oven, set the temperature to 60℃, and dry with forced air for 24h until the AC granules reach constant weight. Cool the dried AC granules to room temperature to obtain pretreated AC granules.

[0097] S2. Preparation of impregnation solution: 1.753 g of tin tetrachloride pentahydrate, 8.925 g of zinc nitrate hexahydrate, and 15 mL of ethanol were added to a beaker and stirred for 15 min until completely dissolved, resulting in a transparent solution, which is solution A. 2.8815 g of citric acid, 8 mL of ethylene glycol, and 15 mL of ethanol were added to a beaker and stirred for 15 min until completely dissolved, resulting in a transparent solution, which is solution B. Solution B was poured into solution A and stirred for 1 h to obtain Sn. 4+ Concentration of 0.1 mol / L, Zn 2+ Impregnation solution with a concentration of 0.6 mol / L.

[0098] Preparation of Sn-Zn / AC particles (S3): 10g of pretreated AC particles from step S1 was weighed using an electronic balance and added to an Erlenmeyer flask. The impregnation solution prepared in step S2 was then added, and the flask was allowed to stand for 2 hours. After soaking, the Erlenmeyer flask was placed in a water bath constant-temperature shaker and shaken at 150 rpm / min for 1 hour to ensure complete impregnation of the pretreated AC particles. The shaken AC particles were then transferred to a 50mL ceramic crucible and placed in a heat-collecting constant-temperature magnetic stirrer. Oil bath heating was used, with the oil bath temperature set at 105℃ for 1 hour. The crucible was then transferred to an electric heating drying oven and dried at 105℃ for 2 hours. After the particles were dried and cooled, the ceramic crucible was wrapped in tin foil and placed in a box furnace for calcination at 600℃ for 3 hours. After cooling, Sn-Zn / AC particles were obtained.

[0099] 2. Construction and application of an electrocatalytic system

[0100] A schematic diagram of the construction of the electrocatalytic system is shown below. Figures 2-3 As shown, firstly, Figure 2This is a schematic diagram of the reactor device in the electrocatalytic system, which consists of a platinum-titanium electrode 1, an electrolyte 2, and Sn-Zn / AC particles 3. Figure 3 This is a schematic diagram of the complete electrocatalytic system, mainly composed of a DC regulated power supply ①, a heat-collecting constant-temperature stirrer ②, stainless steel electrode clamps and platinum-titanium electrodes ③, and Sn-Zn / AC particles ④. In this experiment, the main electrodes were all platinum-titanium plated electrodes with a plate spacing of 2–6 cm; the Sn-Zn / AC particles were filled in a discrete state; the experiment was conducted in an environment with an electrolyte Na₂SO₄ concentration of 5–50 mmol / L; the platinum-titanium electrodes were connected to the DC power supply via electrode clamps and power cords; the electrolytic cell was placed on a magnetic stirrer platform, with a cell voltage of 3–7 V and a magnetic rotor speed of 200–600 rpm.

[0101] The application methods of electrocatalytic systems include the following steps:

[0102] Accurately weigh 0.2 g of methylene blue (MB) solid using an electronic balance, dissolve it thoroughly in ultrapure water, and transfer the solution to a 200 mL volumetric flask and bring it to a final volume. Before the experiment, soak 2 g of the Sn-Zn / AC particles obtained in step 1 above in a 40 mg / L MB solution for 1 h to eliminate the influence of adsorption on the particle electrode (i.e., Sn-Zn / AC particles). The initial conditions were set as follows: constant voltage 5 V, Na2SO4 concentration 20 mmol / L, pH = 4, the particle electrode was filled with the above-treated 2 g of Sn-Zn / AC particles, the rotation speed was constant, and the reaction time was set to 70 min, including 10 min of adsorption without electricity and 60 min of electrocatalytic reaction. Every 10 min, 3.5 mL of liquid water sample was drawn with a syringe, filtered through a 0.22 μm aqueous filter membrane, and transferred to a sample tube. Relevant parameters were set and the absorbance value of the water sample was measured.

[0103] Example 2: Sn-Zn / AC particles, electrocatalytic system, preparation method and application

[0104] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.05 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.4 mol / L, and the calcination time at 600℃ was changed from 3 h to 2 h.

[0105] The other steps and conditions are the same as in Example 1.

[0106] Example 3: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0107] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.2 mol / L, Zn2+ The concentration was changed from 0.6 mol / L to 0.05 mol / L, and the calcination time at 600℃ was changed from 3 h to 4 h.

[0108] The other steps and conditions are the same as in Example 1.

[0109] Example 4: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0110] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.4 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.1 mol / L, and the calcination time at 600℃ was changed from 3 h to 5 h.

[0111] The other steps and conditions are the same as in Example 1.

[0112] Example 5: Sn-Zn / AC particles, electrocatalytic system, preparation method and application

[0113] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.6 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.2 mol / L, and the calcination time at 600℃ was changed from 3 h to 1 h.

[0114] The other steps and conditions are the same as in Example 1.

[0115] Example 6: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0116] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.05 mol / L, and the calcination temperature was changed from 600℃ to 650℃.

[0117] The other steps and conditions are the same as in Example 1.

[0118] Example 7: A Sn-Zn / AC particle, electrocatalytic system, its preparation method, and its application.

[0119] The difference from Example 1 is that in step S2, Zn 2+ The concentration was changed from 0.6 mol / L to 0.05 mol / L, the calcination temperature was changed from 600℃ to 650℃, and the calcination time was changed from 3h to 4h.

[0120] The other steps and conditions are the same as in Example 1.

[0121] Example 8: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0122] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.2 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.1 mol / L, the calcination temperature was changed from 600℃ to 650℃, and the calcination time was changed from 3h to 5h.

[0123] The other steps and conditions are the same as in Example 1.

[0124] Example 9: A Sn-Zn / AC particle, electrocatalytic system, its preparation method and application

[0125] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.4 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.2 mol / L, the calcination temperature was changed from 600℃ to 650℃, and the calcination time was changed from 3h to 1h.

[0126] The other steps and conditions are the same as in Example 1.

[0127] Example 10: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0128] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.6 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.4 mol / L, the calcination temperature was changed from 600℃ to 650℃, and the calcination time was changed from 3h to 2h.

[0129] The other steps and conditions are the same as in Example 1.

[0130] Example 11: A Sn-Zn / AC particle, electrocatalytic system, its preparation method and application

[0131] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.05 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.2 mol / L, the calcination temperature was changed from 600℃ to 500℃, and the calcination time was changed from 3h to 5h.

[0132] The other steps and conditions are the same as in Example 1.

[0133] Example 12: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0134] The difference from Example 1 is that in step S2, Zn 2+ The concentration was changed from 0.6 mol / L to 0.4 mol / L, the calcination temperature was changed from 600℃ to 500℃, and the calcination time was changed from 3h to 1h.

[0135] The other steps and conditions are the same as in Example 1.

[0136] Example 13: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0137] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.2 mol / L, the calcination temperature was changed from 600℃ to 500℃, and the calcination time was changed from 3h to 2h.

[0138] The other steps and conditions are the same as in Example 1.

[0139] Example 14: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0140] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.4 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.05 mol / L, and the calcination temperature was changed from 600℃ to 500℃.

[0141] The other steps and conditions are the same as in Example 1.

[0142] Example 15: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0143] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.6 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.1 mol / L, the calcination temperature was changed from 600℃ to 500℃, and the calcination time was changed from 3h to 4h.

[0144] The other steps and conditions are the same as in Example 1.

[0145] Example 16: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0146] The difference from Example 1 is that in step S2, Sn is... 4+The concentration was changed from 0.1 mol / L to 0.05 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.1 mol / L, and the calcination temperature was changed from 600℃ to 400℃.

[0147] The other steps and conditions are the same as in Example 1.

[0148] Example 17: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0149] The difference from Example 1 is that in step S2, Zn 2+ The concentration was changed from 0.6 mol / L to 0.2 mol / L, the calcination temperature was changed from 600℃ to 400℃, and the calcination time was changed from 3h to 4h.

[0150] The other steps and conditions are the same as in Example 1.

[0151] Example 18: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0152] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.2 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.4 mol / L, the calcination temperature was changed from 600℃ to 400℃, and the calcination time was changed from 3h to 5h.

[0153] The other steps and conditions are the same as in Example 1.

[0154] Example 19: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0155] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.4 mol / L, the calcination temperature was changed from 600℃ to 400℃, and the calcination time was changed from 3h to 1h.

[0156] The other steps and conditions are the same as in Example 1.

[0157] Example 20: A Sn-Zn / AC particle electrocatalytic system, its preparation method, and its application.

[0158] The difference from Example 1 is that in step S2, Sn is... 4+ The concentration was changed from 0.1 mol / L to 0.6 mol / L, Zn 2+ The concentration was changed from 0.6 mol / L to 0.05 mol / L, the calcination temperature was changed from 600℃ to 400℃, and the calcination time was changed from 3h to 2h.

[0159] The other steps and conditions are the same as in Example 1.

[0160] Comparative Example 1: A Sn-Zn / AC particle, electrocatalytic system, its preparation method and application

[0161] The difference from Example 1 is that in step S2, the roasting temperature is changed from 600°C to 700°C.

[0162] The other steps and conditions are the same as in Example 1.

[0163] Comparative Example 2: A particle-based electrocatalytic system, its preparation method, and its application.

[0164] The difference from Example 1 is that, in step S3, Sn was not doped during particle preparation. 4+ Zn 2+ AC particles constitute a direct electrocatalytic system (E system).

[0165] The other steps and conditions are the same as in Example 1.

[0166] Comparative Example 3: An AC particle, electrocatalytic system, its preparation method, and its application

[0167] The difference from Example 1 is that, in step S3, Sn was not doped during particle preparation. 4+ and Zn 2+ This is an AC particle electrocatalytic system (E-AC system).

[0168] The other steps and conditions are the same as in Example 1.

[0169] Comparative Example 4: A Sn / AC particle, electrocatalytic system, its preparation method, and its application

[0170] The difference from Example 1 is that, in step S3, Zn was not doped during particle preparation. 2+ It is a Sn / AC particle electrocatalytic system (E-Sn / AC system).

[0171] The other steps and conditions are the same as in Example 1.

[0172] Comparative Example 5: A Sn-Zn powder, an electrocatalytic system, its preparation method, and its application.

[0173] The difference from Example 1 is that in step 1, AC particles were not doped during particle preparation, and the Sn-Zn powder electrocatalytic system (E-Sn-Zn system) was used.

[0174] 1. Preparation of Sn-Zn powder

[0175] S1. Preparation of impregnation solution: 1.753 g of tin tetrachloride pentahydrate, 8.925 g of zinc nitrate hexahydrate, and 15 mL of ethanol were added to a beaker and stirred for 15 min until completely dissolved, resulting in a transparent solution, which is solution A. 2.8815 g of citric acid, 8 mL of ethylene glycol, and 15 mL of ethanol were added to a beaker and stirred for 15 min until completely dissolved, resulting in a transparent solution, which is solution B. Solution B was poured into solution A and stirred for 1 h to obtain Sn. 4+ Concentration of 0.1 mol / L, Zn 2+ Impregnation solution with a concentration of 0.6 mol / L.

[0176] S2. Preparation of Sn-Zn powder: The impregnation solution obtained in step S1 was transferred to a 50 mL ceramic crucible. The crucible was placed in a heat-collecting constant temperature magnetic stirrer and heated in an oil bath at 105 °C for 1 h. The crucible was then transferred to an electric heating drying oven and dried at 105 °C for 2 h. After drying and cooling, the ceramic crucible was wrapped with tin foil and placed in a box furnace and calcined at 600 °C for 3 h. After cooling, Sn-Zn powder was obtained.

[0177] 2. Construction and application of an electrocatalytic system

[0178] A schematic diagram of the construction of the electrocatalytic system is shown below. Figures 2-3 As shown, firstly, Figure 2 This is a schematic diagram of a reactor device in an electrocatalytic system, consisting of a platinum-titanium electrode 1, an electrolyte 2, and Sn-Zn powder 3. Figure 3 The diagram shows the complete electrocatalytic system, mainly composed of a DC regulated power supply ①, a heat-collecting constant-temperature stirrer ②, stainless steel electrode clamps and platinum-titanium electrodes ③, and Sn-Zn powder ④. In this experiment, the main electrodes were all platinum-titanium plated electrodes with a plate spacing of 2–6 cm; the Sn-Zn powder was filled in a discrete state; the experiment was conducted in an environment with an electrolyte Na₂SO₄ concentration of 5–50 mmol / L; the platinum-titanium electrodes were connected to the DC power supply via electrode clamps and power cords; the electrolytic cell was placed on a magnetic stirrer platform, with a cell voltage of 3–7 V and a magnetic rotor speed of 200–600 rpm.

[0179] The application methods of electrocatalytic systems include the following steps:

[0180] Accurately weigh 0.2 g of methylene blue (MB) solid using an electronic balance, dissolve it thoroughly in ultrapure water, and transfer the solution to a 200 mL volumetric flask and bring it to a final volume. Initial conditions were set as follows: constant voltage 5 V, sodium sulfate concentration 20 mmol / L, pH = 4, particle electrode filled with 2 g of the prepared Sn-Zn powder, constant rotation speed, and a reaction time of 70 min (10 min of adsorption without electrolysis and 60 min of electrocatalytic reaction). Every 10 min, 3.5 mL of liquid water sample was drawn using a syringe, filtered through a 0.22 μm aqueous filter membrane, and transferred to a sample tube. Relevant parameters were set, and the absorbance value of the water sample was measured.

[0181] Comparative Example 6: Sn-Fe / AC particles, electrocatalytic system, preparation method and application

[0182] The difference from Example 1 is that in step S2, zinc nitrate hexahydrate is replaced with ferric chloride to obtain Sn-Fe / AC particles.

[0183] The other steps and conditions are the same as in Example 1.

[0184] Comparative Example 7: Sn-Cu / AC particles, electrocatalytic system, preparation method and application

[0185] The difference from Example 1 is that in step S2, zinc nitrate hexahydrate is replaced with copper sulfate to obtain Sn-Cu / AC particles.

[0186] The other steps and conditions are the same as in Example 1.

[0187] Comparative Example 8: Sn-Mn / AC particles, electrocatalytic system, preparation method and application

[0188] The difference from Example 1 is that in step S2, zinc nitrate hexahydrate is replaced with manganese sulfate to obtain Sn-Mn / AC particles.

[0189] The other steps and conditions are the same as in Example 1.

[0190] Comparative Example 9: A Sn-Ag / AC particle, electrocatalytic system, its preparation method and application

[0191] The difference from Example 1 is that in step S2, zinc nitrate hexahydrate is replaced with silver nitrate to obtain Sn-Ag / AC particles.

[0192] The other steps and conditions are the same as in Example 1.

[0193] Comparative Example 10: Sn-V / AC particles, electrocatalytic system, preparation method and application

[0194] The difference from Example 1 is that in step S2, zinc nitrate hexahydrate is replaced with sodium metavanadate to obtain Sn-V / AC particles.

[0195] The other steps and conditions are the same as in Example 1.

[0196] Physicochemical properties determination of experimental particles and electrocatalytic systems

[0197] 1. SEM characterization

[0198] The pretreated AC particles and Sn-Zn / AC particles from Example 1 were characterized by SEM, and the results are as follows: Figure 4 and Figure 5 As shown.

[0199] from Figure 4 (a) It can be seen that the pretreated AC particles have a rough porous layered structure with numerous grooves and pits on their surface. After magnification, from... Figure 4 (b) It can be seen that the pits on the surface of activated carbon are filled with a large number of tiny pores of different sizes, indicating that it has strong adsorption performance.

[0200] from Figure 5 It can be seen that the surface morphology of AC particles after being loaded with metal undergoes a significant change, compared with... Figure 4 Compared to AC particles magnified 250 times in (a), such as Figure 5 (a) shows that the surface of Sn-Zn / AC particles is covered by an oxide film, which significantly reduces the number of surface pits. Figure 5 (b) It can be seen that the micropores inside the pits on the surface of AC particles are basically covered, compared to Figure 4 In (b), the surface of the Sn-Zn / AC particles is smoother and flatter. The metal oxides not only cover the outer surface of the activated carbon but also some of the internal pores. This metal film coating can prevent organic pollutants from accumulating on the surface of the AC particles, thus extending the service life of the Sn-Zn / AC particles.

[0201] 2. EDS characterization

[0202] EDS (Energy Dispersive X-ray Spectroscopy) characterization is based on the X-rays produced when a material is bombarded by a high-energy electron beam. These X-rays possess characteristic spectra based on their initial atoms. By detecting the energy and density of these characteristic X-rays, the types and abundance of elements present in the sample can be determined. EDS characterization was performed on the pretreated AC particles and Sn-Zn / AC particles in Example 1. Figure 6As can be seen from (a), the surface elements of the pretreated AC particles mainly exist in the form of C and O, with no obvious Sn and Zn peaks. The C content accounts for 97 wt%, and the O content accounts for 3 wt%, with no Sn or Zn elements present. This indicates that the AC particles contain almost no Sn or Zn elements before loading. Figure 6 As shown in (b), the total number of elements in the Sn-Zn / AC particle distribution spectrum mainly exists in the form of C, Sn, Zn, and O. Among them, the content of C accounts for 83.2 wt%, the content of O accounts for 4.8 wt%, the content of Sn is 9.9 wt%, and the content of Zn is 2.1 wt%, which are relatively low proportions. The Sn:Zn atomic ratio on the Sn-Zn / AC particle surface is 2.57:1, which is close to the theoretical atomic ratio (2:1) in the impregnation solution, proving that Sn and Zn elements are successfully loaded on the surface of AC particles.

[0203] 3. XRD characterization

[0204] The crystal structures of the pretreated AC particles and Sn-Zn / AC particles in Example 1 were studied at scanning angles of 10° to 80°. The results are as follows: Figure 7 As shown, both the pretreated AC particles and Sn-Zn / AC particles exhibited characteristic broad peaks of activated carbon at 2θ = 23° and 42.7° (PDF#26-1076), which is the main crystalline phase of activated carbon. After loading metal elements, the diffraction peak intensity of activated carbon decreased, while Sn-Zn / AC particles exhibited sharp characteristic diffraction peaks at 2θ = 26.6°, 33.89°, and 51.78°, corresponding to the (110), (101), and (211) crystal planes of SnO2 (PDF#41-1445, PDF#99-0024, PDF#77-0447, PDF#71-0652), indicating that Sn mainly exists in the form of SnO2. However, no ZnO peaks were detected in the X-ray diffraction pattern, possibly due to low Zn loading, uniform dispersion, or the formation of other low-content compounds.

[0205] To further confirm the form in which Zn exists, Sn-Zn powder (Comparative Example 5) was prepared by drying and calcining a mixed impregnation solution of Sn and Zn without adding AC particles. X-ray diffraction analysis was then performed, and the results are as follows: Figure 8As shown in the image. Analysis revealed that the main peak was SnO2, and it may contain ZnSnO3 (PDF#99-0024 and PDF#28-1486). Combined with SEM and EDS analysis results, although the particle surface contains Zn, no high-boiling-point (2360℃) ZnO was detected. Furthermore, considering that Zn is not easily released during calcination, it can be concluded that Zn and Sn combine to form the ZnSnO3 compound. Therefore, the active material on the surface of Sn-Zn / AC particles mainly consists of SnO2 and ZnSnO3.

[0206] 4. Catalytic principle of electrocatalytic system based on Sn-Zn / AC particles

[0207] The electrocatalytic system based on Sn-Zn / AC particles degrades and removes MB through a combination of direct and indirect electrooxidation. Figure 9 In direct electrocatalysis, Sn-Zn / AC particles form microelectrodes under an electric field. MB is adsorbed onto the surfaces of the main electrode and the microelectrodes through both physical and electroadsorption, and subsequently oxidized and decomposed in the anodic regions of both electrodes. In indirect reactions, driven by voltage and Coulomb forces, the anodic regions of both the main electrode and the microelectrodes exhibit strong oxidizing properties (i.e., electron-withdrawing ability), while the cathode regions exhibit reducing properties (i.e., electron-donating ability). Therefore, the anodic region can convert water or hydroxide ions (OH-) into ions. - The oxidation process generates a large amount of ·OH, while the cathode region can reduce dissolved oxygen to H2O2. This is because ·OH and SO42- in the solution... - • Coexistence, • OH can also promote the formation of small amounts of hydrogen sulfate (HSO4). - ) is converted into SO4 - ·. In ·OH, SO4 - Under the combined action of Mb and H2O2, MB is gradually decomposed into small organic molecules and is eventually mineralized into water and carbon dioxide.

[0208] 5. Determination of Organic Pollutant Removal Efficiency and Energy Consumption Analysis

[0209] The absorbance value of a water sample is closely related to the removal rate. A higher absorbance value indicates a higher concentration of a certain substance in the water sample; a lower absorbance value indicates a lower concentration of the substance. Therefore, the concentration of the removed substance changes during the removal process, and the removal rate is calculated by observing the change in absorbance. Assuming the initial absorbance of the water sample is A0, and the absorbance of the water sample after removal is A1, the removal rate is calculated using the formula: Removal rate = (A0 - A1) / A0 × 100%. In this experiment, MB was selected as a representative organic pollutant.

[0210] Energy consumption analysis refers to the electrical energy consumed during the electrochemical treatment of pollutants. The formula for calculating energy consumption is:

[0211]

[0212] In the formula: EC is energy consumption (kWh / kg); U is DC voltage (V); I is current (A); t is reaction time (h); V is total volume of reaction liquid (L); C0 and C t The values ​​represent the initial and time t values, respectively, the pollutant concentrations (mg / L) in the water samples.

[0213] (1) Sn-Zn / AC particles obtained under different preparation conditions and their MB removal rate

[0214] The table below lists the removal rates of MB by Sn-Zn / AC particles obtained under different preparation conditions. In the MB removal experiment, the experimental conditions were set as follows: cell voltage 5V, pH 4, electrolyte Na2SO4 concentration 20mmol / L, Sn-Zn / AC particle loading 2g, pollutant concentration 40mg / L, and catalytic time 15min.

[0215] Table 1. Particle preparation conditions and MB removal rate statistics.

[0216]

[0217]

[0218] As can be seen from Table 1, over a wide range of calcination temperatures (400–650 °C), Sn 4+ Concentration (0.05–0.6 mol / L), Zn 2+ Within the concentration range (0.05–0.6 mol / L) and calcination time range (1–5 h), the Sn-Zn / AC particles prepared in this application all exhibited excellent MB removal performance. This fully demonstrates that the preparation process has high flexibility and stability, and can prepare particles with excellent catalytic performance under various conditions. In contrast, Comparative Example 1, due to excessively high calcination temperature, resulted in excessive particle dispersion, failing to form a complete product, and thus the AC particles did not successfully load SnO2 and ZnSnO3.

[0219] (2) Sn loaded with different metal ions 4+ / AC particles and different catalytic systems for MB removal rates

[0220] The experimental conditions were as follows: cell voltage 5V, pH 4, electrolyte Na2SO4 concentration 20mmol / L, Sn-Zn / AC particle loading amount 2g, pollutant concentration 40mg / L, and catalytic time 0–50min.

[0221] First, by analyzing the MB removal rate of the particle electrodes prepared in Example 1 and Comparative Examples 6-10, it can be seen that... Figure 10 (a) It can be seen that Sn-Zn / AC particles achieve 100% removal within 20 min. This is because the addition of Zn not only improves the densification of the SnO2 electrode but also reduces the charge transfer resistance of the electrode. Furthermore, the ZnSnO3 formed by Sn and Zn has excellent charge transfer capability, which can improve the catalytic degradation rate of MB by the Sn-Zn / AC particle electrode. However, the removal efficiency of the Sn-Zn electrode is only 82% within 50 min. This is because the Sn-Zn electrode lacks AC particles as a carrier, which severely reduces its contact area and thus its removal rate. Sn-V / AC particles, Sn-Mn / AC particles, Sn-Fe / AC particles, Sn-Cu / AC particles, and Sn-Ag / AC particles only achieve 100% removal within 40 min. This is mainly due to the relatively low catalytic activity of these electrodes. This low catalytic activity not only restricts the generation of active species but also leads to a high charge transfer resistance. Therefore, their charge transfer capability is limited, and they cannot remove MB relatively quickly.

[0222] Secondly, the removal efficiency of the electrocatalytic system for MB in Example 1 was compared with that in Comparative Examples 2 to 4. Figure 10 (a) Within a catalytic time of 30 min, the removal rate of the direct electrocatalytic system (E) was 61.2%, the AC electrocatalytic system (E-AC) was 64.1%, the Sn / AC particle electrocatalytic system (E-Sn / AC) was 79.51%, and the Sn-Zn / AC particle electrocatalytic system (E-Sn-Zn / AC) reached 100%. The high removal rate of the E-Sn-Zn / AC system is attributed to the addition of SnO2 and ZnSnO3, which not only significantly improved the oxygen evolution potential and ·OH yield of the particles, but also reduced the charge transfer resistance, thus accelerating the removal of MB. In contrast, the removal rate of the E system was greatly reduced due to the lack of SnO2 and ZnSnO3 active components and the high specific surface area of ​​AC particles; the E-AC system improved the mass transfer rate due to the addition of AC particles, but the removal rate was still limited; the E-Sn / AC system improved the MB removal rate to a certain extent by introducing SnO2 to increase the oxygen evolution potential and reduce side reactions.

[0223] Further comparison of the energy consumption of the E system, E-Sn / AC system, and E-Sn-Zn / AC system ( Figure 10 (b) Based on the removal of 80% MB, the E-Sn-Zn / AC system has the highest efficiency and lowest energy consumption, requiring only 9 minutes. Figure 10(a) The energy consumption was 43.54 kWh / kg. This is attributed to the significant increase in the reaction rate of the particles and the reduction in energy consumption due to the addition of SnO2 and ZnSnO3. The excellent charge transfer capability of ZnSnO3 reduced the resistance of Sn-Zn / AC particles, increased the oxygen evolution potential, and made the particles more easily polarized to form microelectrodes, thereby reducing oxygen evolution side reactions and promoting the reaction of ·OH and SO42-. - The formation of ·. Under the synergistic effect of particles and active free radicals, MB is rapidly catalytically removed. In contrast, the E-Sn / AC system and the E system, lacking Zn and Sn-Zn respectively, require longer times (40 min and 45 min) to achieve the same removal rate.

[0224] (3) Comparison of the removal effects of Sn-Zn / AC particles on different organic pollutants

[0225] from Figure 11 The comparison shows that the Sn-Zn / AC particles in Example 1 exhibit superior performance in removing various organic pollutants compared to the Sn / AC particles in Comparative Example 4. Specifically, the Sn-Zn / AC particles achieved removal rates of 100% and 95% for Rhodamine B (RhB) and methyl orange, respectively, at a catalytic time of 50 min. In contrast, the Sn / AC particles in Comparative Example 4 achieved removal rates of 89% and 82% for RhB and methyl orange, respectively, at the same time. This comparison clearly demonstrates that the Sn-Zn / AC particles generally achieve higher removal rates for various organic pollutants than the Sn / AC particles, thus highlighting the superior performance and wide applicability of the Sn-Zn / AC particles.

[0226] (4) Active species in electrocatalytic systems

[0227] To determine the active free radical species involved in the activation of persulfate by Sn-Zn / AC particles, paramagnetic resonance (ESR) spectroscopy was performed on the Sn-Zn / AC particle-activated persulfate system. The experimental conditions were: persulfate concentration of 2.5 mmol / L, particle dosage of 2 g, pH = 6, and SO42- was detected at reaction times of 5 min and 10 min. - • and •OH capture test.

[0228] from Figure 12 It can be observed that a clear characteristic peak of DMPO-·OH (1:2:2:1) appeared in the aqueous solution at 5 min, which strongly confirms the presence of ·OH in the reaction system. At the same time, the graph also shows a clear DMPO-SO4... - • Characteristic peaks (manifested as sextuplets of equal intensity). • OH and SO42- -The intensity of the characteristic peaks of the radicals gradually increased, indicating that the number of both radicals increased during the reaction.

[0229] (5) Electrocatalytic stability test of particles

[0230] This invention tests the electrocatalytic stability of the particles prepared in Example 1 and Comparative Example 3 from four perspectives: linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), Tafel slope, and cycle stability.

[0231] The LSV test conditions were as follows: Princeton Versa STAT 4 electrochemical workstation, platinum electrode as counter electrode, Ag / AgCl electrode as reference electrode, 0.1 mol / L Na2SO4 solution as electrolyte, voltage window 0V–1.6V, scan rate 10mV / s, and MB concentration 10mg / L. The EIS and Tafel slope test conditions were as follows: Princeton Versa STAT 4 electrochemical workstation, study sample as working electrode, platinum electrode as counter electrode, Ag / AgCl electrode as reference electrode, 0.1 mol / L Na2SO4 solution as electrolyte, test frequency range 100kHz–0.1Hz, AC amplitude 10mV, and MB concentration 10mg / L.

[0232] First, LSV (Laser-Scanning Potential) involves linearly changing the electrode potential from the initial potential to the termination potential at a specific potential scan rate, while simultaneously measuring the current flowing through the working electrode. As the potential changes, redox reactions occur on the electrode surface, and the current changes accordingly, which can be used to determine the oxygen evolution potential. In this study, the test results are as follows: Figure 13 As shown, at a current density of 0.5 mA / cm² 2 Under the same conditions, the slope of the current-potential curve for Sn-Zn / AC particles is much lower than that for AC particles. The main reason for this difference is that Sn-Zn / AC particles have a higher oxygen evolution overpotential; that is, to achieve the same current density, Sn-Zn / AC particles require a higher potential. Therefore, at the same current density, the oxygen evolution potential of Sn-Zn / AC particles is higher than that of AC particles. This higher oxygen evolution overpotential helps to suppress the occurrence of oxygen evolution side reactions, thereby improving the stability of the entire system.

[0233] Secondly, EIS (Electro-Induced Sequence) measures the impedance of the electrode system at different frequencies, obtaining an impedance-frequency curve that reflects the impedance resistance of the electrode system to alternating current. The semicircular arc in the high-frequency region (0–10 kHz) primarily reflects the solution resistance and charge transfer resistance; the smaller the diameter of the semicircular arc, the smaller the charge transfer resistance of the particles. Experimental results are as follows... Figure 14As shown, the semi-circular diameter of Sn-Zn / AC particles is smaller than that of AC particles, indicating that Sn-Zn / AC particles have a smaller charge transfer resistance. A smaller charge transfer resistance allows the electrode to maintain better performance during multiple cycles of use, reducing energy loss and performance degradation caused by increased resistance, thereby improving the stability of the electrode.

[0234] Furthermore, the Tafel slope describes the polarization of the electrode and reflects the change in overpotential by measuring the current density; this Tafel slope reflects the electron release rate. Experimental results are as follows... Figure 15 As shown, the slope of Sn-Zn / AC particles is lower than that of AC particles. The lower Tafel slope indicates a higher electron release rate, meaning that the reaction kinetics of Sn-Zn / AC particles are faster, which is conducive to the stable existence of the system.

[0235] Finally, to further evaluate the cycling stability of Sn-Zn / AC particles in the electrocatalytic system, five cycles were conducted using MB as the target pollutant at a voltage of 5V, pH=3, Na2SO4 concentration of 20mmol / L, and particle dosage of 2g. The reaction time was set to 20min, and the particles were required to be adsorbed to saturation before entering the reaction system. After the experiment, the particles were separated using a sieve and then ultrasonically cleaned and washed with deionized water, followed by drying in an oven at 60℃. All cycling tests were conducted under the same conditions.

[0236] from Figure 16 As can be seen, the Sn-Zn / AC particles essentially reached adsorption equilibrium after adsorption saturation. In five cycles of testing, the Sn-Zn / AC electrocatalytic system maintained a stable removal efficiency for MB, consistently exceeding 90%. This is mainly attributed to the high oxygen evolution potential and excellent charge transfer capability of the Sn-Zn / AC particles, which enable rapid oxidation and removal of adsorbed pollutants on the surface, effectively mitigating pollutant accumulation on the particle surface.

[0237] ICP tests were performed on the solutions after five cycles of Sn-Zn / AC particles and after one cycle of Sn / AC particles. The results are shown in Table 2.

[0238] Table 2 ICP test results

[0239]

[0240] As can be seen from Table 2, in the first cycle experiment, Sn in Sn-Zn / AC particles 4+ and Zn 2+ The precipitation amounts reached their maximum values, at 420 μg / L and 838.5 μg / L, respectively. With increasing cycle number, Sn...4+ and Zn 2+ The amount of Zn precipitated gradually decreased, reaching 350 μg / L and 411.9 μg / L after the fifth repeated experiment. This change can be attributed to the high content of surface metal oxides on the particles initially, leading to slight detachment of unstable loads due to collisions during the reaction. Simultaneously, because Zn is more reactive than Sn and more readily soluble in acidic solutions, Zn... 2+ The dissolution amount is always greater than that of Sn. 4+ It is worth noting that Zn 2+ The increase in Sn inhibited Sn to some extent 4+ The detachment of Sn-Zn / AC particles after the first reaction is compared to Sn / AC particles without added Zn. 4+ The dissolution rate of Zn decreased significantly, which may be due to... 2+ The anodic protection effectively inhibits Sn 4+ The dissolution of Sn enhances the stability of Sn-Zn / AC particles. Specifically, Sn in Sn / AC particles... 4+ The dissolution rate reached as high as 1490 μg / L, which is the highest among Sn-Zn / AC particles in the first cycle. 4+ 3.548 times the amount dissolved.

[0241] In summary, this invention combines impregnation and calcination methods to prepare Sn-Zn / AC particles, successfully realizing the Sn... 4+ and Zn 2+ The AC support exhibits excellent loading on its surface. The AC supports demonstrate high conductivity, stable chemical properties, and excellent free radical catalytic ability. This support not only loads the active component SnO2 but also contains a small amount of ZnSnO3. SnO2 was chosen due to its high oxygen evolution potential, excellent conductivity, and chemical stability; while the ZnSnO3 loading not only covers the surface of the AC but also penetrates into some of the internal pores, forming an anodic protective layer. This protective layer effectively inhibits Sn... 4+ The dissolution of SnO2 enhances the densification of SnO2 and reduces the charge transfer resistance of the particle electrode, thereby significantly improving the charge transfer efficiency on the Sn-Zn / AC particle surface. Under the influence of an electric field, Sn-Zn / AC particles are more easily polarized to form microelectrodes. The increase in these microelectrodes and their higher oxygen evolution potential effectively suppress the oxygen evolution side reaction during the reaction process, promoting the generation of more hydroxyl radicals (·OH) in the system, and thus improving the catalytic degradation and removal rate of organic pollutants, including methylene blue, rhodamine B, and methyl orange, by the electrocatalytic system based on Sn-Zn / AC particles.

[0242] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An electrocatalytic system, characterized in that, The electrocatalytic system includes a cathode, an anode, a third electrode, and an electrolyte, wherein the third electrode includes Sn-Zn / AC particles; The method for preparing the Sn-Zn / AC particles includes the following steps: adding activated carbon to a material containing Sn. 4+ Zn 2+ After being fully impregnated in the impregnation solution, Sn-Zn / AC particles are obtained by calcining at 500-600 °C for 2-4 h. The Sn-Zn / AC particles are supported by activated carbon and mainly loaded with SnO2 and ZnSnO3. The Sn 4+ With Zn 2+ The molar ratio is 1:(0.25~6).

2. The electrocatalytic system according to claim 1, characterized in that, The method for preparing the impregnation solution includes the following steps: [The steps involve] mixing Sn... 4+ Zn 2+ The solution is mixed with citric acid and alcohol solvents to obtain the impregnation solution.

3. The electrocatalytic system according to claim 1, characterized in that, The Sn 4+ Selected from hydrates of tin chloride, potassium stannate, sodium stannate, or any of the above tin salts.

4. The electrocatalytic system according to claim 1, characterized in that, The Zn 2+ Selected from hydrates of zinc nitrate, zinc sulfate, zinc chloride, or any of the zinc salts mentioned above.

5. The electrocatalytic system according to claim 2, characterized in that, The alcohol solvents include one or more of ethylene glycol, propylene glycol, and butanediol.

6. The application of the electrocatalytic system according to any one of claims 1 to 5 in the degradation and removal of organic pollutants.

7. The application according to claim 6, characterized in that, The organic pollutants include one or more of methylene blue, rhodamine B, and methyl orange.

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