Preparation Method and Application of an Axial Fe-O-Cu Coordination Configuration Electrocatalyst

Abstract

The present invention discloses a preparation method and application of an axial Fe-O-Cu coordination configuration electrocatalyst, belonging to the technical field of electrocatalyst preparation. The preparation method of the axial Fe-O-Cu coordination configuration electrocatalyst of the present invention comprises the following steps: immersing a copper material in an alkaline solution of ammonium persulfate once to obtain a Cu(OH)2 / Cu electrode; immersing the Cu(OH)2 / Cu electrode in a ferric nitrate solution for a second time, taking it out and calcining to obtain an axial Fe-O-Cu coordination configuration electrocatalyst. The axial Fe-O-Cu coordination configuration electrocatalyst prepared by the present invention can be used as an electro-Fenton cathode to promote the formation of 1 O2 in the electro-Fenton system, and realize the degradation of electron-rich antibiotics sulfamethoxazole (SMX), sulfisoxazole and sulfadiazine in complex water bodies.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalyst preparation, and particularly to a preparation method and application of an electrocatalyst with an axial Fe-O-Cu coordination configuration. Background Art

[0002] For many years, the treatment of antibiotic-containing wastewater has faced severe challenges. This is mainly because the stable chemical structure and high toxicity of antibiotics can, to a certain extent, resist the decomposition effects of traditional physical, biological, and chemical methods, resulting in poor removal efficiency of antibiotics. The electro-Fenton advanced oxidation treatment process has become one of the most widely used technologies for the degradation of difficult-to-remove organic substances due to its advantages such as simple operation, environmental friendliness, and outstanding mineralization effect. The electro-Fenton reaction mainly utilizes divalent iron ions (Fe 2+ ) to decompose hydrogen peroxide (H2O2) in-situ produced by the cathodic oxygen reduction reaction through the well-known Haber-Weiss reaction, generating reactive oxygen species (ROS) such as hydroxyl radicals (free state: OH free ; adsorbed state: OH ads ), and using hydroxyl radicals to decompose antibiotics. However, antibiotics usually exist in complex water matrices, and strong oxidizing radicals such as ·OH are usually sensitive to anions, and their oxidizing ability is easily reduced through free radical chain reactions, resulting in low catalytic efficiency. Therefore, some ROS with higher tolerance to organic matter and anions in water are required, such as singlet oxygen (· 1 O2), to achieve the effective decomposition and mineralization of antibiotics. However, the electro-Fenton system based on the Haber-Weiss cycle mechanism usually preferentially generates ·OH and cannot achieve the 1 O2 reactive oxygen species switching, resulting in low removal efficiency of some electron-rich antibiotics such as sulfamethoxazole (SMX), sulfisoxazole, and sulfadiazine in actual complex water bodies. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method and application of an electrocatalyst with an axial Fe-O-Cu coordination configuration to solve the problems existing in the above-mentioned prior art. The electrocatalyst with an axial Fe-O-Cu coordination configuration prepared by the present invention can be used as an electro-Fenton cathode to promote the formation of singlet oxygen ( 1 O2) in the electro-Fenton system, thereby achieving high-efficiency removal of electron-rich antibiotics such as sulfamethoxazole (SMX), sulfisoxazole, and sulfadiazine in complex water bodies.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention: A preparation method of an electrocatalyst with an axial Fe-O-Cu coordination configuration, comprising the following steps:

[0006] The copper material is immersed in an alkaline solution of ammonium persulfate once, washed, and dried once (at 50 - 60 °C) to obtain a Cu(OH)2 / Cu electrode;

[0007] The Cu(OH)2 / Cu electrode is immersed in a ferric nitrate solution twice to generate FeCu(OH)2 nanowires (during the reaction, Fe 3+ ions and Cu(OH)2 undergo a hydrolysis substitution reaction, and through ion exchange, part of the Cu 2+ ions in Cu(OH)2 are replaced to form Fe(OH)3), and then it is taken out, washed, dried twice (at 50 - 60 °C), and calcined to obtain an axial Fe - O - Cu coordination configuration electrocatalyst (Fe - O - Cu / Cu).

[0008] Furthermore, the alkaline solution of ammonium persulfate is an aqueous solution of sodium hydroxide and ammonium persulfate.

[0009] Furthermore, in the alkaline solution of ammonium persulfate, the concentration of sodium hydroxide is 2.0 - 2.5 M, and the concentration of ammonium persulfate is 0.20 - 0.25 M.

[0010] Furthermore, the time for the first immersion is 20 - 25 min.

[0011] Even further, the concentration of sodium hydroxide is 2.5 M, the concentration of ammonium persulfate is 0.25 M; the time for the first immersion is 20 min; the temperature for the first drying is 60 °C.

[0012] Furthermore, the concentration of the ferric nitrate solution is 5 - 10 mM; the time for the second immersion is 10 - 20 s.

[0013] Even further, the amount of the ferric nitrate solution used is 20 - 30 mL.

[0014] Even further, the amount of the ferric nitrate solution used is 30 mL; the concentration of the ferric nitrate solution is 10 mM; the time for the second immersion is 20 s; the temperature for the second drying is 60 °C.

[0015] Furthermore, the heating rate for the calcination is 1 - 2 °C / min, the temperature is 300 - 350 °C, and the time is 2 h.

[0016] Even further, the heating rate for the calcination is 2 °C / min, the temperature is 350 °C, and the time is 2 h.

[0017] Furthermore, before placing the copper material in the alkaline solution of ammonium persulfate, it also includes a step of pretreating the copper material.

[0018] Further, the pretreatment specifically includes: cutting the copper material to a size of 3×4 - 5 cm, and then successively ultrasonically cleaning it in dilute hydrochloric acid, acetone, ethanol, and water for 3 - 5 min; the copper material is a copper mesh.

[0019] The impurities and oxide layer on the surface of the copper material are removed through pretreatment.

[0020] Furthermore, during pretreatment, the copper material is cut to a size of 3×4 cm; the concentration of the dilute hydrochloric acid is 0.1 M; the time for ultrasonic cleaning is 5 min; the drying temperature is 60°C.

[0021] Technical solution two of the present invention: An axial Fe - O - Cu coordination configuration electrocatalyst prepared by the above preparation method.

[0022] Technical solution three of the present invention: An application of the axial Fe - O - Cu coordination configuration electrocatalyst described in claim 9 in the treatment of antibiotic wastewater.

[0023] Furthermore, the application specifically includes: using the axial Fe - O - Cu coordination configuration electrocatalyst as the working electrode to achieve non - radical 1 selective production of O2, and realizing the complete removal of sulfonamide antibiotics in wastewater by a flow - through reactor electro - Fenton system within 1 h.

[0024] The Fe - O - Cu coordination configuration is a special bridged metal coordination structure, which plays an important role in the cathodic oxygen reduction reaction. This configuration (constructs the axial Fe - O - Cu coordination configuration through the ion substitution and recrystallization strategy of Fe for Cu(OH)2) can change the adsorption configuration of oxygen molecules on the metal surface to "terminal adsorption" by changing the distance between metal sites, thereby promoting the formation of superoxide hydrogen radicals (·HO2 - / O2 - ·), and coupling to generate · 1 O2, which can achieve the efficient removal of electron - rich antibiotics sulfamethoxazole (SMX), sulfisoxazole, and sulfadiazine in complex water bodies, and has good application prospects in antibiotic water treatment.

[0025] The present invention discloses the following technical effects:

[0026] (1) The axial Fe - O - Cu coordination configuration electrocatalyst prepared by the present invention can be used as an electro - Fenton cathode to promote the formation of 1 O2 in the electro - Fenton system, and realize the degradation of electron - rich antibiotics sulfamethoxazole (SMX), sulfisoxazole, and sulfadiazine in complex water bodies.

[0027] (2) The axial Fe-O-Cu coordination configuration electrocatalyst of the present invention is an electrochemical cathode material of a bimetallic oxide (Fe-O-Cu / Cu) with a copper mesh as the substrate. It has good electrochemical performance, excellent electrocatalytic degradation performance against the antibiotic sulfamethoxazole (the degradation rate reaches 100%), and has good application prospects in treating organic pollutants. Moreover, the preparation conditions of the axial Fe-O-Cu coordination configuration electrocatalyst of the present invention are mild, the process is simple, the operation is fast, and it is green and environmentally friendly.

[0028] (3) The main raw materials for preparing the axial Fe-O-Cu coordination configuration electrocatalyst of the present invention are metal resources (copper and iron) with rich reserves on the earth. It has high cost performance and practicability, and is a promising heterogeneous electro-Fenton catalyst for treating antibiotics.

[0029] (4) The axial Fe-O-Cu coordination configuration electrocatalyst of the present invention has the characteristics of being cheap, efficient, non-toxic, environmentally friendly, and easy to produce in batches. It can rapidly degrade organic pollutants that are difficult to remove in water, playing a role in protecting and purifying the environment.

[0030] (5) The axial Fe-O-Cu coordination configuration electrocatalyst of the present invention can truly overcome the technical bottleneck of the difficult selective switching of non-free radicals ( 1 O2) in the Fenton reaction (solving the technical bottleneck problem of the poor selectivity of singlet oxygen ( 1 O2) active species in the current traditional electro-Fenton system), and has the practical application potential for effectively removing antibiotics in complex water bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is the SEM diagram of the axial Fe-O-Cu coordination configuration electrocatalyst prepared in Example 1 of the present invention;

[0033] Figure 2 It is the flow-through electrochemical device used in Effect Example 2 of the present invention;

[0034] Figure 3 It is the EPR diagram of Fe-O-Cu / Cu(20s) prepared in Example 1 of the present invention;

[0035] Figure 4Degradation curve of sulfamethoxazole (SMX) by the axial Fe-O-Cu coordination configuration electrocatalyst prepared in Example 1 of the present invention;

[0036] Figure 5 FT-EXAFS spectra of Cu foil, CuO, and the axial Fe-O-Cu coordination configuration electrocatalyst (Fe-O-Cu@Cu) prepared in Example 1 of the present invention. Detailed implementation manners

[0037] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation embodiments of the present invention.

[0038] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0040] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and embodiments of this application are only exemplary.

[0041] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0042] All "parts" mentioned in the following embodiments are "parts by weight".

[0043] Example 1

[0044] A preparation method of an axial Fe-O-Cu coordination configuration electrocatalyst:

[0045] (1) Prepare the copper mesh: Cut the copper mesh to a size of 3×4 cm, then ultrasonically clean it with 0.1 M dilute hydrochloric acid, acetone, ethanol, and deionized water for 5 min each to remove surface impurities and oxide layers, and finally dry it in an oven (60 °C) to obtain the pretreated copper mesh.

[0046] (2) Immerse the pretreated copper mesh in an aqueous solution of sodium hydroxide (NaOH) and ammonium persulfate ((NH4)2S2O8) (the concentration of sodium hydroxide in the aqueous solution is 2.5 M, and the concentration of ammonium persulfate is 0.25 M) for 20 min to generate Cu(OH)2 nanowires. Subsequently, rinse it with deionized water and dry it in an oven (60 °C) to obtain a Cu(OH)2 / Cu electrode with the copper mesh as the substrate.

[0047] (3) Immerse the Cu(OH)2 / Cu electrode with the copper mesh as the substrate prepared in step (2) in 30 mL of an aqueous solution of Fe(NO3)3·9H2O with a concentration of 10 mM for 20 s to generate FeCu(OH)2 nanowires. Subsequently, rinse it with deionized water and dry it in an oven (60 °C) to obtain an FeCu(OH)2 / Cu electrode with the copper mesh as the substrate.

[0048] (4) Place the FeCu(OH)2 / Cu electrode with the copper mesh as the substrate prepared in step (3) in a muffle furnace, and under an air atmosphere, heat it to 350 °C at a heating rate of 2 °C / min and calcine it for 2 h to obtain a recrystallized axial Fe-O-Cu coordination configuration electrocatalyst (Fe-O-Cu / Cu(20 s)).

[0049] Example 2

[0050] Same as Example 1, except that the immersion time in step (3) is 10 s, and finally the electrocatalyst Fe-O-Cu / Cu(10 s) is obtained.

[0051] Example 3

[0052] Same as Example 1, except that the immersion time in step (3) is 30 s, and finally the electrocatalyst Fe-O-Cu / Cu(30 s) is obtained.

[0053] Effect Example 1

[0054] The SEM image of the axial Fe-O-Cu coordination configuration electrocatalyst prepared in Example 1 of the present invention is shown in Figure 1 .

[0055] From Figure 1It can be seen that the iron-copper bimetal oxide grows on the copper mesh in the form of hollow nanowires, with a uniform morphology and interlaced with each other, having a large number of electrochemically active sites. This one-dimensional nanowire structure is also beneficial to shortening the electron transport distance, increasing the contact area with substances, and enhancing the electrocatalytic performance.

[0056] Effect Example 2

[0057] Measure the degradation performance of the axial Fe-O-Cu coordination configuration electrocatalyst prepared in Example 1 of the present invention against antibiotics.

[0058] (1) Dissolve 0.1 g of sulfamethoxazole (SMX) in 100 mL of deionized water, stir ultrasonically until dissolved, and then transfer it to a volumetric flask with a volume of 1 L for constant volume and ultrasonic homogenization to obtain a target pollutant stock solution of sulfamethoxazole with a concentration of 100 mg / L.

[0059] (2) Prepare a 100 mL mixed solution containing 0.1 M sodium sulfate and 10 mg / L sulfamethoxazole as the electro-Fenton electrolyte and add it to the flowing electrolytic cell of the electrochemical device. Use the electrocatalyst prepared in Examples 1 to 3 of the present invention as the working electrode, a platinum mesh as the counter electrode, and Ag / AgCl as the reference electrode (see the flowing electrochemical device in Figure 2 ), apply an external bias voltage of -1.2 V in the constant current mode to initiate the electro-Fenton degradation of sulfamethoxazole, and sample and detect the pollutant concentration every 5 minutes. The results are shown in Figure 4 .

[0060] When the electro-Fenton degradation of sulfamethoxazole is initiated for 5 minutes, measure the EPR signal diagram of the electrocatalyst prepared in Example 1 of the present invention. The results are shown in Figure 3 .

[0061] From Figure 3 Three typical 1 O2 characteristic peaks of 1:1:1 can be clearly observed, indicating that the axial Fe-O-Cu / Cu electro-Fenton catalyst of the present invention can effectively generate 1 O2 to achieve the selective production of non-radical active species. In addition, the singlet oxygen EPR signal of Fe-O-Cu / Cu(20S) is significantly stronger than that of Fe-O-Cu / Cu(10S) and Fe-O-Cu / Cu(30S), indicating that Fe-O-Cu / Cu9(20S) has the most Fe-O-Cu axial sites.

[0062] Figure 4 The Y-axis in

[0063] From Figure 4It can be seen that when the electrocatalyst (Fe-O-Cu / Cu(20s)) prepared in Example 1 of the present invention is used as the working electrode, sulfamethoxazole is basically completely removed when the electro-Fenton reaction proceeds for 25 min. The reason is that the Fe-O-Cu / Cu / electro-Fenton system can effectively generate 1 O2 and rapidly degrade the antibiotic sulfamethoxazole, effectively overcoming the 1 technical limitations of difficult production of O2 and difficult removal of electron-rich antibiotic pollutant sulfamethoxazole in the electro-Fenton system.

[0064] In the subsequent experiments of the present invention, the conditions for pretreating the copper mesh were verified for the preparation method of the axial Fe-O-Cu coordination configuration electrocatalyst. It was found that when the size of the copper mesh was 3×4 - 5 cm and the ultrasonic cleaning time was 3 - 5 min, the impurities and oxide layers on the surface of the copper material could be removed.

[0065] The conditions for the Cu(OH)2 / Cu electrode based on the copper mesh were verified. It was found that when the concentration of sodium hydroxide in the aqueous solution of sodium hydroxide (NaOH) and ammonium persulfate ((NH4)2S2O8) was 2.0 - 2.5 M, the concentration of ammonium persulfate was 0.20 - 0.25 M, and the immersion time was 20 - 25 min, the Cu(OH)2 / Cu electrode based on the copper mesh prepared could provide sufficient 3+ Fe ion substitution sites to realize the preparation of the axial Fe-O-Cu coordination configuration electrocatalyst.

[0066] The conditions for the FeCu(OH)2 / Cu electrode based on the copper mesh were verified. It was found that when the dosage of the iron nitrate solution was 20 - 30 mL and the concentration of the iron nitrate solution was 5 - 10 mM, the FeCu(OH)2 / Cu electrode based on the copper mesh prepared could realize the preparation of the axial Fe-O-Cu coordination configuration electrocatalyst.

[0067] The conditions for the axial Fe-O-Cu coordination configuration electrocatalyst were verified. It was found that when the heating rate of calcination was 1 - 2 °C / min, the temperature was 300 - 350 °C, and the time was 2 h, the axial Fe-O-Cu coordination configuration electrocatalyst could be obtained.

[0068] Effect Example 3

[0069] FT-EXAFS spectral tests were carried out on Cu foil (Cu foil), CuO and the axial Fe-O-Cu coordination configuration electrocatalyst (Fe-O-Cu@Cu) prepared in Example 1 of the present invention. The results are shown in Figure 5 .

[0070] From Figure 5It can be seen that, compared with the Cu foil, the missing characteristic peak at Cu-Cu in Fe-O-Cu@Cu indicates the atomic dispersion of Fe in Cu(OH)2. In addition, the similar M-O and M-O-M (M represents metal) bonds of Cu-O and Cu-O-Cu in Fe-O-Cu@Cu and CuO prove the formation of the coordination structure of Fe-O-Cu, and the displacement in the R space is caused by the strong interaction between Fe and the O-Cu bond.

[0071] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. Application of an axial Fe-O-Cu coordination configuration electrocatalyst in the treatment of antibiotic wastewater, characterized in that, The preparation method of the axial Fe-O-Cu coordination configuration electrocatalyst comprises the following steps: Immerse the copper material in the alkaline solution of ammonium persulfate once to obtain a Cu(OH)2 / Cu electrode; Immerse the Cu(OH)2 / Cu electrode in the iron nitrate solution a second time, take it out and calcine it to obtain an axial Fe-O-Cu coordination configuration electrocatalyst; The alkaline solution of ammonium persulfate is an aqueous solution of sodium hydroxide and ammonium persulfate; In the alkaline solution of ammonium persulfate, the concentration of sodium hydroxide is 2.0 - 2.5 M, and the concentration of ammonium persulfate is 0.20 - 0.25 M; The time of the first immersion is 20 - 25 min; The concentration of the iron nitrate solution is 5 - 10 mM; the time of the second immersion is 10 - 20 s; The heating rate of the calcination is 1 - 2 °C / min, the temperature is 300 - 350 °C, and the time is 2 h; The copper material is a copper mesh.

2. The application according to claim 1, characterized in that Before placing the copper material in the alkaline solution of ammonium persulfate, it also includes the step of pre-treating the copper material.

3. The application according to claim 2, wherein The specific pre-treatment includes: ultrasonically cleaning the copper material in dilute hydrochloric acid, acetone, ethanol and water in sequence for 3 - 5 min.

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