Application of Cobalt-loaded Nitrogen-doped Hollow Carbon Spheres in Electrocatalytic Hydrogenolysis and Dechlorination of Florfenicol

Abstract

The present invention discloses the use of cobalt-loaded nitrogen-doped hollow carbon spheres in the electrocatalytic hydrogenolysis and dechlorination of florfenicol. In the present invention, cobalt is loaded onto the nitrogen-doped hollow carbon spheres to obtain cobalt-loaded nitrogen-doped hollow carbon spheres (Co / N-HCS). Cobalt-loaded nitrogen-doped hollow carbon spheres (Co / N-HCS) can efficiently remove the carbon-chlorine bond in the antibiotic florfenicol molecule, demonstrating very high florfenicol degradation and dechlorination rates.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical technology, and in particular to application of cobalt-loaded nitrogen-doped hollow carbon spheres in electrocatalytic hydrogenolysis and dechlorination of florfenicol. Background Art

[0002] Antibiotics are an emerging pollutant that has attracted widespread attention from researchers in recent years. Antibiotics can be used to treat bacterial infections because they have excellent antibacterial activity. However, most antibiotics are included in China's list of emerging pollutants because antibiotics discharged into the environment during production and application can induce many threats over time. For example, florfenicol (FLO) is a broad-spectrum halogenated antibiotic (containing F and Cl atoms) that is most widely used in animal husbandry and aquaculture. Excreted FLO is present in many media, including water and sediments. Due to its chemical inertness and stable CF-bonds, it is almost impossible to degrade under natural conditions, and florfenicol discharged in wastewater has potential biological toxicity.

[0003] Currently, the commonly used treatment methods for antibiotics in water include physical, biological, and chemical methods. Chemical methods, including chemical catalytic oxidation, electrochemical catalysis, photocatalysis, and advanced oxidation technologies based on persulfate activation, have been widely used to degrade antibiotics in water due to their simplicity, high efficiency, mild reaction conditions, and low risk of secondary pollution.

[0004] Electrochemical catalysis plays a significant role in the electrocatalytic dechlorination of florfenicol by hydrogenolysis. This process utilizes the continuous electrons provided by a powerful cathode to selectively complete the dechlorination of florfenicol by hydrogenolysis. Therefore, the selection of cathode catalyst materials is crucial for improving the dechlorination efficiency of florfenicol. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide an application of cobalt-loaded nitrogen-doped hollow carbon spheres in the electrocatalytic hydrogenolysis dechlorination of florfenicol, which can efficiently remove the carbon-chlorine bond in the antibiotic florfenicol molecule.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] Application of cobalt-loaded nitrogen-doped hollow carbon spheres in electrocatalytic florfenicol hydrogenolysis and dechlorination, wherein the preparation method of the cobalt-loaded nitrogen-doped hollow carbon spheres is as follows:

[0008] (1) mixing ethyl orthosilicate, ethanol, ammonia water and water, then adding dopamine hydrochloride aqueous solution, stirring and filtering, and drying to obtain polydopamine-coated silica spheres;

[0009] (2) grinding the polydopamine-coated silica balls and calcining them under a nitrogen atmosphere to obtain nitrogen-doped carbon-coated silica balls;

[0010] (3) dispersing the nitrogen-doped carbon-coated silica spheres in hydrofluoric acid and stirring, and then washing and drying to obtain nitrogen-doped hollow carbon spheres;

[0011] (4) dispersing the nitrogen-doped hollow carbon spheres in ethanol, then adding Co(NO3)2 ethanol solution, stirring in a water bath and evaporating the solution, calcining, and finally treating with acid to obtain cobalt-loaded nitrogen-doped hollow carbon spheres;

[0012] Cobalt-loaded nitrogen-doped hollow carbon spheres are loaded on a conductive substrate to form a working electrode. The working electrode is used as the cathode of an electrochemical reaction device, and wastewater containing florfenicol is added to carry out an electrocatalytic hydrogenolysis dechlorination reaction.

[0013] As a preferred technical solution, in step (2), the calcination temperature is 800°C.

[0014] As a preferred technical solution, in step (4), the calcination temperature is 400°C.

[0015] As a preferred technical solution, the concentration of florfenicol in the wastewater containing florfenicol is 2-30 mg / L.

[0016] The beneficial effects of the present invention are:

[0017] The present invention loads cobalt onto nitrogen-doped hollow carbon spheres to produce cobalt-loaded nitrogen-doped hollow carbon spheres (Co / N-HCS). Single-atom Co forms coordination with nitrogen atoms on the N-HCS, leaving it in an electron-deficient state, greatly enhancing its ability to adsorb and activate carbon-chloride bonds. The hollow carbon structure and high specific surface area of ​​the N-HCS both improve the dispersibility of Co (increasing atomic utilization) and enhance the mass transfer efficiency of low-concentration florfenicol in water at the electrode surface. Furthermore, the Co / N-HCS of the present invention has similar polarity to florfenicol, promoting its adsorption. Due to the combined effects of these factors, the cobalt-loaded nitrogen-doped hollow carbon spheres (Co / N-HCS) can efficiently remove carbon-chlorine bonds from the antibiotic florfenicol molecule, demonstrating very high florfenicol degradation and dechlorination rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention provides the following drawings for illustration:

[0019] Figure 1 This is the SEM image of N-HCS prepared in Comparative Example 1;

[0020] Figure 2This is the SEM image of Co / N-HCS prepared in Example 1;

[0021] Figure 3 The degradation efficiency of florfenicol by N-HCS and Co / N-HCS changes with time in the electrocatalytic reaction;

[0022] Figure 4 is the liquid phase peak area of ​​N-HCS and Co / N-HCS p-florfenicol at 180 min in the electrocatalytic reaction;

[0023] Figure 5 The degradation efficiency of Co / N-HCS for different concentrations of florfenicol changes with time in the electrocatalytic reaction;

[0024] Figure 6 is the liquid phase peak area of ​​Co / N-HCS to different concentrations of florfenicol at 180 min in the electrocatalytic reaction. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0026] Comparative Example 1: Preparation of N-HCS working electrode

[0027] (1) 1 mL of tetraethyl orthosilicate (TEOS), 24 mL of ethanol (C2H5OH), 1 mL of NH3·H2O, and 80 mL of deionized water (H2O) were mixed and stirred rapidly for 30 min. Then, 8 mL of dopamine hydrochloride (0.258 M) was added and magnetic stirring was continued for 24 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain polydopamine-coated silica spheres SiO2@PDA.

[0028] (2) SiO2@PDA was ground and placed in a tube furnace under nitrogen atmosphere at 5℃·min -1 The heating rate was set at 800℃ for 2h to obtain nitrogen-doped carbon-coated silica spheres SiO2@NC.

[0029] (3) The SiO2@NC powder was dispersed in a 10% HF solution and magnetically stirred for 1 h, washed, and dried to obtain nitrogen-doped hollow carbon spheres N-HCS.

[0030] (4) Weigh 13 mg of N-HCS into a 20 ml vial, add 3 ml of ethanol and 30 μL of Nafion adhesive, and sonicate for 10 min to form a uniform catalyst ink solution. Then, apply the catalyst ink droplets to the pretreated carbon paper to prepare the working electrode.

[0031] Example 1: Preparation of Co / N-HCS working electrode

[0032] (1) 1 mL of tetraethyl orthosilicate (TEOS), 24 mL of ethanol (C2H5OH), 1 mL of NH3·H2O, and 80 mL of deionized water (H2O) were mixed and stirred rapidly for 30 min. Then, 8 mL of dopamine hydrochloride (0.258 M) was added and magnetic stirring was continued for 24 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain polydopamine-coated silica spheres SiO2@PDA.

[0033] (2) SiO2@PDA was ground and placed in a tube furnace under nitrogen atmosphere at 5℃·min -1 The heating rate was set at 800℃ for 2h to obtain nitrogen-doped carbon-coated silica spheres SiO2@NC.

[0034] (3) The SiO2@NC powder was dispersed in a 10% HF solution and magnetically stirred for 1 h, washed, and dried to obtain nitrogen-doped hollow carbon spheres N-HCS.

[0035] (4) Weigh 40 mg of N-HCS and add it to 80 mL of ethanol, mix well, and ultrasonicate for 20 min. Weigh 10.4 mg of Co(NO3)2·6H2O and add it to 20 mL of ethanol and ultrasonicate it well. Slowly add it to the above solution and continue ultrasonicating for 10 min. Stir magnetically at 500 r / min for 20 min. Place it in a water bath and stir vigorously at 80 °C until it is evaporated to dryness. Finally, place it in a tube furnace and evaporation at 5 °C·min -1 The temperature was raised at a rate of 400°C for 40 min to obtain 5% Co / N-HCS.

[0036] (5) Weigh 30 mg of 5% Co / N-HCS and add 10 ml of 1 M HCl. Stir vigorously for 30 min, filter, wash, and dry to obtain cobalt-loaded nitrogen-doped hollow carbon spheres Co / N-HCS.

[0037] (6) Weigh 13 mg of Co / N-HCS into a 20 ml vial, add 3 ml of ethanol and 30 μL of Nafion adhesive, and sonicate for 10 min to form a uniform catalyst ink solution. Then, apply the catalyst ink droplets to the pretreated carbon paper to prepare the working electrode.

[0038] Effects of N-HCS and Co / N-HCS on the Electrocatalytic Hydrogenolysis of Florfenicol

[0039] Test 1: Test the electrocatalytic hydrogenolysis dechlorination effect of the working electrode in 20 mM florfenicol. The specific steps are as follows:

[0040] (1) Activation of the working electrode: Place the working electrode, platinum electrode and reference electrode in the prepared 50mM Na2SO4 electrode activation solution and scan CV to activate the working electrode.

[0041] (2) A double-chamber H-type electrolytic cell was used, and 40 mL of Na2SO4 electrolyte was added to the cathode and anode chambers respectively. The electrolyte was vented with N2 for 5 minutes to remove the air in the electrolyte.

[0042] (3) Add 0.16 mL of 5.00 g / L florfenicol stock solution to the cathode chamber and stir for 5 min to evenly disperse the pollutants.

[0043] (4) Use a glass sampler to take a sample of approximately 0.5 mL. Connect to the workstation, set the parameters, and start the test.

[0044] (5) Take samples of approximately 0.5 mL at predetermined times (0, 30, 60, ..., 180 min).

[0045] (6) After the electrochemical reaction, the obtained sample is placed in a high performance liquid chromatography for sampling. According to the established standard curve, the concentration of florfenicol at different reaction times is calculated; finally, the degradation rate (η) is calculated as (C0-C t ) / C0*100%, where C0 is the initial concentration of florfenicol in the reaction in mg / L; C t is the concentration of florfenicol at time t in mg / L; dechlorination rate (η) = (S0-S t ) / S0*100%, wherein S0 is the liquid phase peak area of ​​florfenicol at the initial stage of the reaction; S t is the liquid phase peak area of ​​florfenicol Cl corresponding to the end of the reaction.

[0046] The results show (such as Figure 3 and Figure 4 As shown in Figure 3, at -0.9 V, after electrochemical catalytic hydrogenation and dechlorination, the degradation rate and dechlorination rate of florfenicol increased with time. At 180 min, the degradation rate of N-HCS was 95%, and the dechlorination rate was 26.8%, while the degradation rate of Co / N-HCS reached 99.9%, and the dechlorination rate was more than 98%.

[0047] The above experimental data prove that Co / N-HCS has higher electrocatalytic activity in the electrocatalytic hydrogenolysis and dechlorination of florfenicol.

[0048] Test 2: Test the electrocatalytic hydrogenolysis dechlorination effect of the working electrode in different concentrations of florfenicol. The specific steps are as follows:

[0049] (1) Activation of the working electrode: Place the working electrode, platinum electrode and reference electrode in the prepared 50mM Na2SO4 electrode activation solution and scan CV to activate the working electrode.

[0050] (2) A double-chamber H-type electrolytic cell was used, and 40 mL of Na2SO4 electrolyte was added to the cathode and anode chambers respectively. The electrolyte was vented with N2 for 5 minutes to remove the air in the electrolyte.

[0051] (3) Add 0.016 mL, 0.08 mL, 0.16 mL, and 0.24 mL of 5.00 g / L florfenicol stock solution to the cathode tank, respectively, and stir for 5 minutes to evenly disperse the pollutants. The florfenicol concentrations were adjusted to 2 mg / L, 10 mg / L, 20 mg / L, and 30 mg / L, respectively.

[0052] (4) Use a glass sampler to take a sample of approximately 0.5 mL. Connect to the workstation, set the parameters, and start the test.

[0053] (5) Take samples of approximately 0.5 mL at predetermined times (0, 30, 60, ..., 180 min).

[0054] (6) After the electrochemical reaction, the obtained sample is placed in a high performance liquid chromatography for sampling. According to the established standard curve, the concentration of florfenicol at different reaction times is calculated; finally, the degradation rate (η) is calculated as (C0-C t ) / C0*100%, where C0 is the initial concentration of florfenicol in the reaction in mg / L; C t is the concentration of florfenicol at time t in mg / L; dechlorination rate (η) = (S0-S t ) / S0*100%, wherein S0 is the liquid phase peak area of ​​florfenicol at the initial stage of the reaction; S t is the liquid phase peak area of ​​florfenicol Cl corresponding to the end of the reaction.

[0055] According to the above steps, electrochemical experiments were carried out using Co / N-HCS at different initial concentrations of florfenicol, 2 mg / L, 10 mg / L, 20 mg / L, and 30 mg / L. The results showed that as the initial concentration of florfenicol increased, the degradation rate of florfenicol by Co / N-HCS (such as Figure 5 As shown) still remains above 99%, and the dechlorination rate (as shown) Figure 6 shown) remains above 98%.

[0056] The present invention loads cobalt onto nitrogen-doped hollow carbon spheres to produce cobalt-loaded nitrogen-doped hollow carbon spheres (Co / N-HCS). Single-atom Co forms coordination with nitrogen atoms on the N-HCS, leaving it in an electron-deficient state, greatly enhancing its ability to adsorb and activate carbon-chloride bonds. The hollow carbon structure and high specific surface area of ​​the N-HCS both improve the dispersibility of Co (increasing atomic utilization) and enhance the mass transfer efficiency of low-concentration florfenicol in water at the electrode surface. Furthermore, the Co / N-HCS of the present invention has similar polarity to florfenicol, promoting its adsorption. Due to the combined effects of these factors, the cobalt-loaded nitrogen-doped hollow carbon spheres (Co / N-HCS) can efficiently remove carbon-chlorine bonds from the antibiotic florfenicol molecule, demonstrating very high florfenicol degradation and dechlorination rates.

[0057] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. Application of cobalt-loaded nitrogen-doped hollow carbon spheres in electrocatalytic florfenicol hydrogenolysis and dechlorination, characterized in that: The preparation method of the cobalt-loaded nitrogen-doped hollow carbon spheres is as follows: (1) mixing ethyl orthosilicate, ethanol, ammonia water and water, then adding dopamine hydrochloride aqueous solution, stirring and filtering, and drying to obtain polydopamine-coated silica spheres; (2) grinding the polydopamine-coated silica balls and calcining them under a nitrogen atmosphere to obtain nitrogen-doped carbon-coated silica balls; (3) dispersing the nitrogen-doped carbon-coated silica spheres in hydrofluoric acid and stirring, and then washing and drying to obtain nitrogen-doped hollow carbon spheres; (4) dispersing the nitrogen-doped hollow carbon spheres in ethanol, then adding Co(NO3)2 ethanol solution, stirring in a water bath and evaporating the solution, calcining, and finally treating with acid to obtain cobalt-loaded nitrogen-doped hollow carbon spheres; Cobalt-loaded nitrogen-doped hollow carbon spheres are loaded on a conductive substrate to form a working electrode. The working electrode is used as the cathode of an electrochemical reaction device, and wastewater containing florfenicol is added to carry out an electrocatalytic hydrogenolysis dechlorination reaction.

2. The use of cobalt-loaded nitrogen-doped hollow carbon spheres according to claim 1 in electrocatalytic florfenicol hydrogenolysis and dechlorination, characterized in that: In step (2), the calcination temperature is 800°C.

3. The use of cobalt-loaded nitrogen-doped hollow carbon spheres according to claim 1 in electrocatalytic florfenicol hydrogenolysis and dechlorination, characterized in that: In step (4), the calcination temperature is 400°C.

4. The use of cobalt-loaded nitrogen-doped hollow carbon spheres according to claim 1 in electrocatalytic florfenicol hydrogenolysis and dechlorination, characterized in that: In the wastewater containing florfenicol, the concentration of florfenicol is 2-30 mg / L.

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