A method for electrochemical catalytic degradation of bisphenol A based on iron-nitrogen-carbon particle electrodes

Abstract

The present invention discloses a method for electrochemical catalytic degradation of bisphenol A based on iron-nitrogen-carbon particle electrodes. The present invention uses cellulose, ferric nitrate and melamine as precursors, prepares Fe-N-C material by a solvent-free method, and constructs a Fe-N-C / peroxydisulfate three-dimensional electrode system to electrochemically catalyze the removal of bisphenol A. The Fe-N-C material serves as both a particle electrode in the three-dimensional electrode and a catalyst for peroxydisulfate. The oxidation of peroxydisulfate mainly occurs on the catalyst surface. The Fe-N-C material has good adsorption capacity, which allows pollutants to be enriched on its surface for removal. The sp 2‑ The presence of hybrid structure, π-π bond and electron-rich functional groups gives it broad application prospects in the field of persulfate advanced oxidation treatment.

Description

Technical Field

[0001] The invention belongs to the field of sewage purification and treatment in environmental protection, and particularly relates to a method for electrochemically catalytically degrading bisphenol A based on iron-nitrogen-carbon particle electrodes. Background Art

[0002] Bisphenol A (BPA), a typical environmental endocrine disruptor, is highly toxic and difficult to completely degrade. Industrially used in the synthesis of materials such as polycarbonate plastics and epoxy resins, BPA comes into contact with humans in a variety of consumer products, including food containers, water pipes, toys, medical devices, and electronics. Exposure to BPA in the environment poses a significant threat to human health. Several studies have confirmed that BPA, as an endocrine disruptor, interacts with multiple physiological receptors, such as estrogen receptors α / β, estrogen-related receptor γ, androgen receptors, and thyroid hormone receptors, adversely affecting the reproductive organs, nervous system, cardiovascular system, metabolic system, and immune system. In laboratory studies, BPA has even been linked to cancer. Due to its growing demand and toxicological effects, BPA has been listed as a major contaminant of concern in water treatment. Therefore, eliminating BPA and its derivatives from water and wastewater is an urgent issue.

[0003] Current methods for removing bisphenol A include: biodegradation, photodegradation, adsorption, phytoremediation, and advanced oxidation processes. Among them, biodegradation of bisphenol A has high requirements for bacterial species and the environment. Photodegradation and phytoremediation are less efficient in removing bisphenol A. After adsorbents adsorb bisphenol A, the pollutants will remain on the adsorbents, requiring subsequent treatment. Therefore, advanced oxidation processes (AOPs) are one of the most promising technologies for removing biologically recalcitrant organic pollutants. Among them, electrochemical oxidation technology generally operates at room temperature and pressure. The electrode device is small and simple, easy to adjust, and basically does not require the addition of additional chemicals. It uses the electrolysis process to directly or indirectly exert its effect. The entire process is low-cost and is an environmentally friendly and clean treatment process. In recent years, studies have found that three-dimensional electrode electrochemical oxidation technology has broken through the limitations of traditional two-dimensional electrodes with small processing capacity and low efficiency, and has shown good results in the field of wastewater treatment. In the electrolytic cell, in addition to the traditional cathode and anode as the two-dimensional main electrodes, additional particle materials are filled as the third electrode to form a three-dimensional electrode. Under the action of a high-intensity electric field, there are countless bipolar electrodes in the electrolytic cell of the three-dimensional electrode, which increases the reaction contact area, shortens the distance the reactants move to the electrodes, and greatly increases the rate, which can significantly drive the removal efficiency of pollutants. Summary of the Invention

[0004] In order to address the shortcomings and deficiencies of the prior art, the object of the present invention is to provide a method for electrochemical catalytic degradation of bisphenol A based on iron-nitrogen-carbon particle electrodes.

[0005] The present invention uses cellulose, ferric nitrate and melamine as precursors, prepares Fe-NC materials through a solvent-free method, and constructs a Fe-NC / peroxydisulfate three-dimensional electrode system to electrochemically catalyze the removal of bisphenol A. Fe-NC materials, as particle electrodes in this three-dimensional electrode system, have abundant reactive sites on their surface, which can promote the charge storage and release reactions. These reactive sites can provide more catalytic centers, reduce charge transfer impedance, and enhance the electrochemical activity of electrode materials. At the same time, Fe-NC materials also act as catalysts for peroxydisulfate (PDS). Fe-NC materials have good adsorption capacity, which allows pollutants to be enriched on their surface for removal. The presence of sp2-hybridized structures, π-π bonds and electron-rich functional groups in carbon materials has made carbon materials widely used in the field of peroxydisulfate advanced oxidation treatment.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for electrochemically catalytically degrading bisphenol A based on an iron-nitrogen-carbon particle electrode comprises the following steps:

[0008] (1) A mixture of bisphenol A (BPA) and anhydrous sodium sulfate was used as the electrolyte, a stainless steel sheet and a dimensionally stable anode (DSA) iridium tantalum electrode sheet were used as the cathode and anode of the main electrode, respectively. Fe-NC catalytic material was added to the electrolyte to act as the third electrode to construct a three-dimensional electrode reaction system.

[0009] (2) After the Fe-NC catalytic material has saturated adsorption of bisphenol A, a peroxydisulfate (PDS) activator is added to the electrolyte, and electrolysis is performed by applying power to achieve electrochemical catalytic degradation of bisphenol A.

[0010] Preferably, the concentration of bisphenol A (BPA) in the electrolyte of step (1) is 10 to 20 mg / L.

[0011] Preferably, the mass ratio of bisphenol A to anhydrous sodium sulfate in step (1) is (1-2) mg:1 g.

[0012] Preferably, the mass ratio of bisphenol A to Fe-NC catalytic material in step (1) is 1:(10-25).

[0013] Preferably, the pH of the electrolyte in step (1) is 2 to 10; more preferably 4 to 10.

[0014] Preferably, the stainless steel sheet and the DSA iridium-tantalum electrode sheet in step (1) are placed vertically in the electrolyte.

[0015] More preferably, the size of the stainless steel sheet and the DSA iridium tantalum electrode sheet in step (1) is 50 mm*25 mm*1 mm; the distance between the main electrodes is 3 cm; and the volume of the electrolyte is 200 mL.

[0016] Preferably, the Fe-NC catalytic material in step (1) is prepared by the following method:

[0017] Fe(NO3)3·9H2O, melamine and cellulose are mixed and ground to obtain a yellow dry powder precursor, which is then calcined at high temperature in stages, cooled, washed and dried to obtain a Fe-NC catalytic material.

[0018] More preferably, the ratio of Fe(NO3)3·9H2O, melamine and cellulose is 1 mmol: (0.1-0.3) g: (0.1-0.3) g.

[0019] More preferably, the staged high-temperature calcination refers to: first heating from room temperature to 160-200°C and keeping warm for 90-110 minutes, then heating from 160-200°C to 230-250°C and keeping warm for 90-110 minutes, and finally heating to 790-810°C and keeping warm for 80-100 minutes.

[0020] More preferably, the heating rate of the staged high-temperature calcination is 1 to 10° C. / min.

[0021] More preferably, the washing means first soaking in an inorganic acid solution and then washing with water until neutral; the inorganic acid solution is 1 mol / L H2SO4 solution; and the soaking time is 24 hours.

[0022] More preferably, the drying refers to natural drying at room temperature.

[0023] More preferably, the cellulose is extracted from Miscanthus sinensis by the following method:

[0024] The herb is boiled in boiling water, dried, and crushed, and then added to a nitric acid ethanol solution at a mass-to-liquid ratio of 1:25. After heating at 90°C for 2 hours, the resulting cellulose powder is rinsed with the nitric acid ethanol solution, then washed with hot water until neutral, filtered, and dried to obtain cellulose; wherein the volume ratio of nitric acid to ethanol in the nitric acid ethanol solution is, and the nitric acid is a dilute nitric acid solution.

[0025] Preferably, the saturated adsorption of bisphenol A by the Fe-NC catalytic material in step (2) is carried out under stirring, and the saturated adsorption time is 5 to 10 minutes.

[0026] Preferably, in step (2), the ratio of the Fe-NC catalytic material to the PDS activator is (1-2.5) g: (1-3) mmol.

[0027] Preferably, the current density of the electrolysis in step (2) is 0.15 to 0.35A.

[0028] Preferably, the electrolysis time in step (2) is 1 to 30 minutes.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] This study utilizes Fe-NC electrocatalytic materials as particle electrodes to construct an electrochemical three-dimensional electrode-PDS advanced oxidation technology system for efficient BPA removal. Compared to traditional treatment methods, the plant cellulose used in this study is widely available and safe and non-toxic. The catalytic material preparation process is simple and controllable, free of contaminants, making it easy to operate experimentally. The energy used is clean electricity, resulting in no secondary pollution. Among the various systems, Fe-NC demonstrated the best removal efficiency for BPA, achieving a 96% removal rate. This work provides insightful insights into the removal of BPA through the combined activation, degradation, and polymerization of PDS using an applied electric field. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 and 2 are SEM images of the Fe-NC electrocatalytic material of the present invention and EDS mapping images of Fe, N, C, and O.

[0032] Figure 2 The XPS spectra of the Fe-NC electrocatalytic material of the present invention before and after the electrochemical catalytic reaction are (a) total spectrum, (b) C spectrum, (c) O spectrum, (d) Fe spectrum, and (e) N spectrum.

[0033] Figure 3 is the removal effect of Fe-NC on bisphenol A in different systems.

[0034] Figure 4 This is a diagram of the removal efficiency of bisphenol A for electrochemical removal with different Fe-NC electrocatalyst dosages.

[0035] Figure 5 This is a graph showing the effect of different current densities on the electrochemical removal efficiency of bisphenol A.

[0036] Figure 6 This is a diagram of the removal efficiency of bisphenol A under different pH conditions.

[0037] Figure 7 It is the degradation / polymerization pathway and intermediate product of BPA in the E / PDS / Fe-NC three-dimensional electrode system. DETAILED DESCRIPTION

[0038] The present invention will be described in further detail below with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.

[0039] In the examples of the present invention, if the specific conditions are not specified, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. All raw materials and reagents used without specifying the manufacturer are conventional products that can be purchased from the market.

[0040] Analysis and characterization methods of the present invention: X-ray photoelectron spectroscopy (XPS) analysis was performed using an ANELVA AES-430S photoelectron spectrometer with a 300W Al-Kα spectrometer to quantitatively and qualitatively identify surface functional groups. X-ray diffraction (XRD) was used to determine the crystal structure and morphology of the samples at a scan rate of 0.5° / s over a 2θ range of 5-70°. Thermogravimetric analysis (TGA) was performed using an SDTQ600 thermal analyzer. The morphology was characterized using a scanning electron microscope (SEM, JEOL-7800, Japan). Energy dispersive spectroscopy (EDS) was used to investigate the surface morphology and elemental composition of the prepared samples. A ZetaSizer (Malvern ZetaSizer Nano-ZS, Malvern) was used to measure the surface charge of the composites at different pH values. Accurate MS / MS spectra of BPA and its oxidation products were analyzed using molecular ion scanning mode (m / z 50-1100) and negative electrospray ionization (dual AJS ESI). Based on experimental and theoretical m / z values, a molecular formula for the identified product was proposed. The specific method is as follows: UPLC-Q-TOF-MS was used to analyze the intermediate product. The aqueous phase was extracted using an LC-18 solid-phase extraction column (6 mL / 500 mg, Supelco, USA), eluting with 6 mL of methanol and 6 mL of water. Subsequently, 200 mL of sample was loaded, and the analytes were eluted with 6 mL of methanol. An ECLIPS PLUS C18 column (100 mm × 2.1 mm, 1.8 μm, Agilent, USA) was used for elution using a gradient solvent from 20% A:80% B (0-3 min) to 90% A:10% B (3-10 min) and 10% A:90% B (10-15 min) at a flow rate of 0.300 mL / min, where A was methanol and B was 0.2% (v / v) formic acid in water. The column was maintained at 40°C.

[0041] Example 1

[0042] Pretreatment of King Grass and its cellulose extraction:

[0043] Cut the grass into small pieces and clean the surface dust with tap water. Rinse twice with ultrapure water, boil in a pot of ultrapure water, and then dry in an oven. Pulverize with a grinder, pass the pulverized sample through a 100-mesh sieve, and dry in a desiccator to constant weight. Extract cellulose using the nitric acid-ethanol method: add the prepared nitric acid ethanol solution (1:4 by volume) to the cellulose powder at a mass-to-liquid ratio of 1:25. Install a condenser reflux device and heat in a 90°C water bath for approximately 2 hours. Rinse the resulting cellulose powder twice with nitric acid ethanol solution (same concentration as above) and then wash with hot water until the washing solution is neutral. Drain the filtrate and place in a 60°C oven for 12 hours.

[0044] Solvent-free preparation process of Fe-NC electrocatalytic materials:

[0045] First, 5 mmol of Fe(NO₃)₃·9H₂O was weighed and thoroughly ground in a mortar. Then, 0.75 g of melamine and 0.75 g of cellulose were added to the mortar and ground for 60 minutes. After 20 minutes of grinding, the sample became slightly moist due to the release of hydrated ions in the Fe(NO₃)₃·9H₂O. However, with continued grinding, the sample gradually dried, ultimately yielding a yellow dry powder precursor. The precursor was placed in a clean porcelain boat and heat-treated in a nitrogen-protected tube furnace using a programmed temperature ramp. The temperature ramp was as follows: the tube furnace was heated from room temperature to 180°C for 100 minutes, then from 180°C to 240°C for 100 minutes, and finally to 800°C for 90 minutes, all at a rate of 5°C / min. After the temperature ramp was complete, the sample was allowed to cool naturally to room temperature. The resulting black solid powder was then immersed in a 1 mol / L H₂SO₄ solution for 24 hours. The obtained product was washed with distilled water until neutral, filtered and dried at room temperature to obtain the final product.

[0046] Comparison of Bisphenol A Removal by Different Systems

[0047] Pure electrical degradation system: Stainless steel sheets and DSA iridium tantalum electrodes were used as the cathode and anode of the main electrodes, respectively. The electrode plates were 50mm*25mm*1mm in size, and the distance between the main electrodes was 3cm. They were vertically immersed in a beaker containing 200mL of a mixed aqueous solution of bisphenol A electrolyte (10mg / L bisphenol A and 35mmol / L Na2SO4). The degradation experiment was carried out at a current of 0.15A and a stirring speed of 600rpm on a multi-connected digital display magnetic stirrer for 30min.

[0048] Pure PDS degradation system: PDS was added to a 200 mL beaker containing a mixed aqueous solution of bisphenol A electrolyte (10 mg / L bisphenol A and 35 mmol / L Na2SO4) to a PDS dosage of 0.2 mmol / L. The system was stirred at 600 rpm on a multi-connected digital magnetic stirrer for 30 min for degradation experiments.

[0049] Fe-N-C + PDS degradation system: Fe-NC electrocatalyst material was added to a beaker containing 200 mL of a mixed aqueous solution of bisphenol A electrolyte (10 mg / L bisphenol A and 35 mmol / L Na2SO4) to a dosage of 0.25 g / L of Fe-NC electrocatalyst in the system. After stirring at 600 rpm on a multi-connected digital display magnetic stirrer for 10 minutes, PDS was added to the system to a dosage of 0.2 mmol / L. The system was stirred at 600 rpm on a multi-connected digital display magnetic stirrer for 30 minutes for the degradation experiment.

[0050] Fe-N-C+ electrical degradation system: stainless steel sheets and DSA iridium tantalum electrodes were used as the cathode and anode of the main electrodes, respectively. The electrode plate size was 50mm*25mm*1mm, and the distance between the main electrodes was 3cm. They were vertically immersed in a beaker containing 200mL of a mixed aqueous solution of bisphenol A electrolyte (10mg / L bisphenol A and 35mmol / L Na2SO4). Fe-NC electrocatalytic material was then added to the mixed aqueous solution of bisphenol A electrolyte to construct a three-dimensional electrode system. The dosage of Fe-NC electrocatalyst in the system was 0.25g / L. After stirring at 600rpm on a multi-connected digital display magnetic stirrer for 10min, the degradation experiment was carried out at a current of 0.15A and a stirring speed of 600rpm on a multi-connected digital display magnetic stirrer for 30min.

[0051] Fe-N-C+PDS+power-on degradation system: stainless steel sheets and DSA iridium-tantalum electrodes were used as the cathode and anode of the main electrodes, respectively. The electrode plate size was 50mm*25mm*1mm, and the distance between the main electrodes was 3cm. They were vertically immersed in a beaker containing 200mL of a mixed aqueous solution of bisphenol A electrolyte (10mg / L bisphenol A and 35mmol / L Na2SO4). Fe-NC electrocatalytic material was then added to the mixed aqueous solution of bisphenol A electrolyte to construct a three-dimensional electrode system. The dosage of Fe-NC electrocatalyst in the system was 0.25g / L. After stirring at 600rpm on a multi-connected digital display magnetic stirrer for 10min, PDS was added to make the dosage of PDS in the system 0.2mmol / L. The degradation experiment was carried out at a current of 0.15A and a stirring speed of 600rpm on a multi-connected digital display magnetic stirrer for 30min.

[0052] Fe-NC adsorption degradation system: Fe-NC electrocatalyst material was added to a beaker containing 200 mL of a mixed aqueous solution of bisphenol A electrolyte (10 mg / L bisphenol A and 35 mmol / L Na2SO4) to a dosage of 0.25 g / L of Fe-NC electrocatalyst in the system. The mixture was stirred at 600 rpm on a multi-connected digital magnetic stirrer for 10 minutes and then continued to stir at 600 rpm on a multi-connected digital magnetic stirrer for 30 minutes for degradation experiments.

[0053] After degradation of the above system, 0.7 mL of electrolyte sample was taken from each system and immediately injected into a 2 mL centrifuge tube containing 0.7 mL of methanol. The sample was filtered using a 0.22 μm organic nylon filter membrane. The pollutant concentration was analyzed using a high performance liquid chromatography (HPLC, 7 Infinity II, Agilent, Germany) equipped with an Agilent C1260 column (18.4*6 mm, 100.2 μm, USA). The results are shown in Figure 2. Figure 3 As shown, the BPA removal rate was 3.5% in the pure electrical degradation system, 1.9% in the pure PDS degradation system, 78% in the Fe-N-C + PDS degradation system, 11% in the Fe-N-C + electrical degradation system, 95% in the Fe-N-C + PDS + electrical degradation system, and 9.3% in the Fe-NC adsorption degradation system alone. It can be seen that the BPA removal efficiency was best when Fe-NC, PDS, and an external electric field were added simultaneously, followed by Fe-NC and PDS. The effect of adding Fe-NC and an external electric field was similar to that of Fe-NC adsorption alone. Adding an external electric field or PDS alone had little effect on BPA removal. Fe-NC alone had almost no adsorption effect on BPA. It can be used as a three-dimensional particle electrode. When an appropriate electric field is applied, electrostatic induction forms microelectrodes with different charges at both ends of the particle. Electrochemical reactions can occur on the surfaces of both the main electrode and the particle electrode, thereby expanding the reaction area and promoting mass transfer. The prepared material has a large surface area that enhances the adhesion of PDS and bisphenol A to the surface, exposing more catalytic active sites for improved activity, sufficient mass transfer for simpler electrode kinetics, and a multidimensional conductive network for enhanced conductivity and mechanical strength, which can better activate PDS and thus has a positive effect on the removal of bisphenol A.

[0054] Example 2

[0055] Pretreatment of King Grass and its cellulose extraction:

[0056] Cut the grass into small pieces and clean the surface dust with tap water. Rinse twice with ultrapure water, boil in a pot of ultrapure water, and then dry in an oven. Pulverize with a grinder, pass the pulverized sample through a 100-mesh sieve, and dry in a desiccator to constant weight. Extract cellulose using the nitric acid-ethanol method: add the prepared nitric acid ethanol solution (1:4 by volume) to the cellulose powder at a mass-to-liquid ratio of 1:25. Install a condenser reflux device and heat in a 90°C water bath for approximately 2 hours. Rinse the resulting cellulose powder twice with nitric acid ethanol solution (same concentration as above) and then wash with hot water until the washing solution is neutral. Drain the filtrate and place in a 60°C oven for 12 hours.

[0057] Solvent-free preparation process of Fe-NC electrocatalytic materials:

[0058] First, 5 mmol of Fe(NO₃)₃·9H₂O was weighed and thoroughly ground in a mortar. Then, 0.75 g of melamine and 0.75 g of cellulose were added to the mortar and ground for 60 minutes. After 20 minutes of grinding, the sample became slightly moist due to the release of hydrated ions in the Fe(NO₃)₃·9H₂O. However, with continued grinding, the sample gradually dried, ultimately yielding a yellow dry powder precursor. The precursor was placed in a clean porcelain boat and heat-treated in a nitrogen-protected tube furnace using a programmed temperature ramp. The temperature ramp was as follows: the tube furnace was heated from room temperature to 180°C for 100 minutes, then from 180°C to 240°C for 100 minutes, and finally to 800°C for 90 minutes, all at a rate of 5°C / min. After the temperature ramp was complete, the sample was allowed to cool naturally to room temperature. The resulting black solid powder was then immersed in a 1 mol / L H₂SO₄ solution for 24 hours. The obtained product was washed with distilled water until neutral, filtered and dried at room temperature to obtain the final product.

[0059] BPA removal with different Fe-NC electrocatalytic material dosages:

[0060] A stainless steel sheet and a DSA iridium-tantalum electrode sheet were used as the cathode and anode of the main electrode, respectively. The electrode plates were 50 mm * 25 mm * 1 mm in size, and the distance between the main electrodes was 3 cm. They were vertically immersed in a beaker containing 200 mL of a mixed aqueous solution of bisphenol A electrolyte (10 mg / L bisphenol A and 35 mmol / L Na2SO4). Fe-NC electrocatalytic material was then added to the mixed aqueous solution of bisphenol A electrolyte to construct a three-dimensional electrode system, and an electrochemical catalytic degradation experiment of BPA was carried out as follows:

[0061] 0.0200g, 0.0300g, 0.0400g, and 0.0500g of the prepared Fe-NC electrocatalyst were added to four 200ml portions of the bisphenol A electrolyte mixed aqueous solution (10mg / L bisphenol A and 35mmol / L Na2SO4). After stirring at 600rpm on a multi-connected digital magnetic stirrer for 10 minutes, 0.2mmol / L PDS was added and a constant current of 0.15A was applied to the experiment. 0.7mL of the electrolyte solution was sampled 1 minute, 2 minutes, 3 minutes, 5 minutes, 8 minutes, 12 minutes, 20 minutes, and 30 minutes after the start of the experiment and immediately injected into a 2mL centrifuge tube containing 0.7mL of methanol. The samples were filtered using a 0.22μm organic nylon filter membrane. The concentration of pollutants was analyzed using a high performance liquid chromatography (HPLC, 7 Infinity II, Agilent, Germany) equipped with an Agilent C1260 column (18.4*6 mm, 100.2 μm, USA). Figure 4 As shown in the figure: when the power-on experiment was carried out for 30 minutes and the dosage of Fe-NC electrocatalyst was 0.25 g / L, the BPA removal rate was the best at 88%, and the corresponding BPA removal reaction rate constant (k / min) was 0.0489 / min, where R 2 Between (0.94~0.99).

[0062] Example 3

[0063] Pretreatment of King Grass and its cellulose extraction:

[0064] Cut the grass into small pieces and clean the surface dust with tap water. Rinse twice with ultrapure water, boil in a pot of ultrapure water, and then dry in an oven. Pulverize with a grinder, pass the pulverized sample through a 100-mesh sieve, and dry in a desiccator to constant weight. Extract cellulose using the nitric acid-ethanol method. Add the prepared nitric acid ethanol solution (volume ratio 1:4) to the cellulose powder at a mass-to-liquid ratio of 1:25. Install a condenser reflux device and heat in a 90-degree water bath for approximately 2 hours. Rinse the resulting cellulose powder twice with nitric acid ethanol solution (concentration as above), then wash with hot water until the washing solution is neutral. Drain the filtrate and place in a 60-degree oven for 12 hours.

[0065] Preparation method of Fe-NC electrocatalytic materials by solvent-free method:

[0066] First, 5 mmol of Fe(NO₃)₃·9H₂O was weighed and thoroughly ground in a mortar. Then, 0.75 g of melamine and 0.75 g of cellulose were added to the mortar and ground for 60 minutes. After 20 minutes of grinding, the sample became slightly moist due to the release of hydrated ions in the Fe(NO₃)₃·9H₂O. However, with continued grinding, the sample gradually dried, ultimately yielding a yellow dry powder precursor. The precursor was placed in a clean porcelain boat and heat-treated in a nitrogen-protected tube furnace using a programmed temperature ramp. The temperature ramp was as follows: the tube furnace was heated from room temperature to 180°C for 100 minutes, then from 180°C to 240°C for 100 minutes, and finally to 800°C for 90 minutes, all at a rate of 5°C / min. After the temperature ramp was complete, the sample was allowed to cool naturally to room temperature. The resulting black solid powder was then immersed in a 1 mol / L H₂SO₄ solution for 24 hours. The obtained product was washed with distilled water until neutral, filtered and dried at room temperature to obtain the final product.

[0067] BPA removal at different current densities:

[0068] A stainless steel sheet and a DSA iridium-tantalum electrode sheet were used as the cathode and anode of the main electrode, respectively. The electrode plates were 50 mm * 25 mm * 1 mm in size, and the distance between the main electrodes was 3 cm. They were vertically immersed in a beaker containing 200 mL of a mixed aqueous solution of bisphenol A electrolyte (10 mg / L bisphenol A and 35 mmol / L Na2SO4). Fe-NC electrocatalytic material was then added to the mixed aqueous solution of bisphenol A electrolyte to construct a three-dimensional electrode system, and an electrochemical catalytic degradation experiment of BPA was carried out as follows:

[0069] Three portions (0.0500g) of the prepared Fe-NC electrocatalyst were weighed and added to three portions (200ml) of a bisphenol A electrolyte mixed aqueous solution (10mg / L bisphenol A and 35mmol / L Na2SO4). After stirring at 600rpm on a multi-connected digital magnetic stirrer for 10 minutes, 0.2mmol / L PDS was added and the experiment was started with constant currents of 0.15A, 0.25A, and 0.35A, respectively. 0.7mL of the electrolyte solution was sampled 1 minute, 2 minutes, 3 minutes, 5 minutes, 8 minutes, 12 minutes, 20 minutes, and 30 minutes after the start of the experiment and immediately injected into a 2mL centrifuge tube containing 0.7mL of methanol. The samples were filtered using a 0.22μm organic nylon filter membrane. The concentration of pollutants was analyzed using a high performance liquid chromatography (HPLC, 7 Infinity II, Agilent, Germany) equipped with an Agilent C1260 column (18.4*6 mm, 100.2 μm, USA). Figure 5As shown in the figure: when the power-on experiment was carried out for 30 minutes, the Fe-NC electrocatalyst dosage was 0.25 g / L and the constant current was 0.35 A, the BPA removal rate could reach 91%.

[0070] Example 4

[0071] Pretreatment of King Grass and its cellulose extraction:

[0072] Cut the grass into small pieces and clean the surface dust with tap water. Rinse twice with ultrapure water, boil in a pot of ultrapure water, and then dry in an oven. Pulverize with a grinder, pass the pulverized sample through a 100-mesh sieve, and dry in a desiccator to constant weight. Extract cellulose using the nitric acid-ethanol method. Add the prepared nitric acid ethanol solution (volume ratio 1:4) to the cellulose powder at a mass-to-liquid ratio of 1:25. Install a condenser reflux device and heat in a 90-degree water bath for approximately 2 hours. Rinse the resulting cellulose powder twice with nitric acid ethanol solution (concentration as above), then wash with hot water until the washing solution is neutral. Drain the filtrate and place in a 60-degree oven for 12 hours.

[0073] Preparation method of Fe-NC electrocatalytic materials by solvent-free method:

[0074] First, 5 mmol of Fe(NO₃)₃·9H₂O was weighed and thoroughly ground in a mortar. Then, 0.75 g of melamine and 0.75 g of cellulose were added to the mortar and ground for 60 minutes. After 20 minutes of grinding, the sample became slightly moist due to the release of hydrated ions in the Fe(NO₃)₃·9H₂O. However, with continued grinding, the sample gradually dried, ultimately yielding a yellow dry powder precursor. The precursor was placed in a clean porcelain boat and heat-treated in a nitrogen-protected tube furnace using a programmed temperature ramp. The temperature ramp was as follows: first, the tube furnace was heated from room temperature to 180°C for 100 minutes, then from 180°C to 240°C for 100 minutes, and finally to 800°C for 90 minutes, all at a rate of 5°C / min. After the temperature ramp was complete, the sample was allowed to cool naturally to room temperature, and the resulting black solid powder was immersed in 1 mol / L H₂SO₄ for 24 hours. The obtained product was washed with distilled water until neutral, filtered and dried at room temperature to obtain the final product.

[0075] BPA removal under different pH conditions:

[0076] A stainless steel sheet and a DSA iridium-tantalum electrode sheet were used as the cathode and anode of the main electrode, respectively. The electrode plates were 50 mm * 25 mm * 1 mm in size, and the distance between the main electrodes was 3 cm. They were vertically immersed in a beaker containing 200 mL of a mixed aqueous solution of bisphenol A electrolyte (10 mg / L bisphenol A and 35 mmol / L Na2SO4). Fe-NC electrocatalytic material was then added to the mixed aqueous solution of bisphenol A electrolyte to construct a three-dimensional electrode system, and an electrochemical catalytic degradation experiment of BPA was carried out as follows:

[0077] Five portions (0.0500g) of the prepared Fe-NC electrocatalyst were weighed and added to 200ml of a bisphenol A electrolyte mixed aqueous solution (10mg / L bisphenol A and 35mmol / L Na2SO4) at pH values of 2, 4, 6, 8, and 10, respectively. The mixture was stirred at 600rpm on a multi-connected digital magnetic stirrer for 10 minutes. After that, 0.2mmol / L PDS was added and a constant current of 0.15A was applied to the mixture. 0.7mL of electrolyte solution was sampled 1, 2, 3, 5, 8, 12, 20, and 30 minutes after the start of the experiment and immediately injected into a 2mL centrifuge tube containing 0.7mL of methanol. The samples were filtered using a 0.22μm organic nylon filter membrane. The concentration of pollutants was analyzed using a high performance liquid chromatography (HPLC, 7 Infinity II, Agilent, Germany) equipped with an Agilent C1260 column (18.4*6 mm, 100.2 μm, USA). Figure 6 As shown in the figure: when the power-on experiment was carried out for 30 minutes, the dosage of Fe-NC electrocatalyst was 0.25 g / L, the constant current was 0.15 A, and the initial pH value of the pollutant mixture was 8, the BPA removal rate could reach 93%.

[0078] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for electrochemical catalytic degradation of bisphenol A based on iron-nitrogen-carbon particle electrodes, characterized in that: The following steps are involved: (1) A mixture of bisphenol A and anhydrous sodium sulfate was used as the electrolyte, a stainless steel sheet and a dimensionally stable iridium-tantalum electrode sheet were used as the cathode and anode of the main electrode, respectively, and Fe-NC catalytic material was added to the electrolyte to act as the third electrode to construct a three-dimensional electrode reaction system; (2) After the Fe-NC catalytic material is saturated with bisphenol A, a peroxydisulfate activator is added to the electrolyte, and electrolysis is performed by applying power to achieve electrochemical catalytic degradation of bisphenol A; The Fe-NC catalytic material in step (1) is prepared by the following method: Fe(NO3)3·9H2O, melamine and cellulose were mixed and ground to obtain a yellow dry powder precursor, which was then calcined at high temperature in stages, cooled, washed and dried to obtain the Fe-NC catalytic material. The mass ratio of bisphenol A to Fe-NC catalytic material in step (1) is 1:(10-25); In step (2), the ratio of the Fe-NC catalytic material to the peroxodisulfate activator is (1-2.5) g: (1-3) mmol; The electrolysis time in step (2) is 1 to 30 minutes; The ratio of Fe(NO3)3·9H2O, melamine and cellulose is 1mmol:(0.1-0.3)g:(0.1-0.3)g.

2. The electrochemical catalytic degradation method of bisphenol A based on iron-nitrogen-carbon particle electrodes according to claim 1, characterized in that: In the electrolyte of step (1), the concentration of bisphenol A is 10-20 mg / L.

3. The electrochemical catalytic degradation method of bisphenol A based on iron-nitrogen-carbon particle electrodes according to claim 1, characterized in that: The pH of the electrolyte in step (1) is 2 to 10.

4. The electrochemical catalytic degradation method of bisphenol A based on iron-nitrogen-carbon particle electrodes according to claim 1, characterized in that: The mass ratio of bisphenol A and anhydrous sodium sulfate in step (1) is (1-2) mg:1 g.

5. The electrochemical catalytic degradation method of bisphenol A based on iron-nitrogen-carbon particle electrodes according to claim 1, characterized in that: The current density of the electrolysis in step (2) is 0.15 to 0.35 A.

6. The electrochemical catalytic degradation method of bisphenol A based on iron-nitrogen-carbon particle electrodes according to claim 1, characterized in that: The staged high-temperature calcination refers to: firstly heating from room temperature to 160-200°C and keeping it warm for 90-110 minutes, then heating from 160-200°C to 230-250°C and keeping it warm for 90-110 minutes, and finally heating to 790-810°C and keeping it warm for 80-100 minutes; The cellulose is extracted from royal bamboo grass.

7. The electrochemical catalytic degradation method of bisphenol A based on iron-nitrogen-carbon particle electrodes according to claim 3, characterized in that: The pH of the electrolyte in step (1) is 4 to 10.

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