A method for efficiently mineralizing organic pollutants using series electrochemical technology

Abstract

The present invention provides a method for the efficient mineralization of organic pollutants by series electrochemical method, which belongs to the field of water treatment technology. 1 O2+SO4 ·– ‑TRS system, the system adopts a two-electrode DC power supply, and sequentially includes a singlet oxygen degradation system and a sulfate radical degradation system; the singlet oxygen degradation system uses a Fe / CNT electrode as a cathode and a Ti4O7 as an anode; the sulfate radical degradation system uses a Fe / CA electrode as a cathode and a Ti4O7 as an anode. 1 O2) and sulfate radicals (SO4 ·‑ ) 1 O2+SO4 ·– The TRS system can achieve 90-100% mineralization of sulfonamide antibiotics (SAs) within 30 minutes, which is much higher than that of the single 1 O2 / HO · / SO4 ·– ‑AOP system.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a method for series electrochemical high-efficiency mineralization of organic pollutants. Background Art

[0002] Over the past two decades, with the growth of the world's population and the expansion of economic activity, safe access to freshwater supplies has been increasingly threatened. Various emerging contaminants (ECs) have also been detected in water bodies. These contaminants, called ECs, are toxic and hazardous chemicals that pose significant risks to the ecological environment or human health but are not yet included in environmental management or where existing management measures are insufficient. Common examples include endocrine disruptors, antibiotics, persistent organic pollutants, and microplastics. Most emerging contaminants are not yet subject to regulatory oversight. They are essential substances in industrial and agricultural production and daily life and can enter the aquatic environment through pathways such as sewage treatment plant effluent, landfill leachate, livestock and poultry wastewater, and agricultural surface runoff. These exogenous substances are typically present at trace or trace levels in aquatic media, but they pose significant risks to public health and ecosystems.

[0003] Advanced oxidation processes (AOPs) are the most advanced water purification technologies that can efficiently produce highly reactive species and have attracted extensive attention from researchers in the field of environmental water pollution control. Deep mineralization of pollutants is the most ideal choice for AOPs to achieve water safety, avoiding secondary pollution from intermediate products. From a chemical perspective, the mineralization of AOPs is mainly mediated by various reactive oxygen species (ROS), such as HO · , SO4 ·– and 1 The reaction pathways of ROS with organic pollutants mainly depend on the reaction characteristics of the active species and the chemical structure of the pollutants.

[0004] Take HO · and SO4 ·– The mediated free radical pathway mainly involves three types of reactions, namely electron transfer, hydrogen abstraction and electrophilic addition reaction. · It can react non-selectively and instantaneously with pollutants in water. The hydrogen abstraction reaction is HO · The main pathway for the oxidation of saturated compounds (alkanes and fatty alcohols, etc.). · It tends to react with unsaturated compounds (containing double bonds, heterocycles, benzene rings, etc.) through electrophilic addition. ·– More inclined to selectively attack the electron-donating groups of target pollutants. 1 The O2-mediated non-radical pathway reacts with unsaturated compounds through electron transfer and electrophilic addition reactions, showing high selectivity for electron-rich groups.

[0005] However, traditional AOPs, which use a single or coexisting active species, suffer from low utilization efficiency of target pollutants due to factors such as the short ROS lifetime, substrate competition, and complex reaction pathways. This requires the use of large amounts of chemical reagents and long reaction cycles to achieve complete mineralization of organic matter, resulting in increased costs and potential adverse environmental impacts. Improving the mineralization efficiency of AOPs for target pollutants while using low chemical dosages and energy inputs is an urgent issue that needs to be addressed. Summary of the Invention

[0006] In view of the above problems existing in the prior art, the present invention provides a method for the efficient mineralization of organic pollutants by tandem electrochemical method. 1 O2) and sulfate radicals (SO4 ·- ) 1 O2+SO4 ·– -TRS system can achieve 90-100% mineralization of sulfonamide antibiotics (SAs) within 30 minutes, which is much higher than that of single 1 O2 / HO · / SO4 ·– -AOP system.

[0007] The technical solutions of the present invention are as follows:

[0008] The present invention provides a method for the efficient mineralization of organic pollutants by series electrochemical method. 1 O2+SO4 ·– -TRS system, which uses a two-electrode DC power supply and includes a singlet oxygen degradation system and a sulfate radical degradation system in sequence;

[0009] The singlet oxygen degradation system uses a Fe / CNT electrode as a cathode and Ti4O7 as an anode; the sulfate radical degradation system uses a Fe / CA electrode as a cathode and Ti4O7 as an anode.

[0010] The present invention also provides the above 1 O2+SO4 ·– -The method for efficiently mineralizing organic pollutants using a TRS system comprises the following steps:

[0011] (1) Wastewater containing sulfonamide antibiotics SAs and potassium peroxymonosulfonate (PMS) electrolyte solution are mixed and injected into the singlet oxygen degradation system. A constant current is passed through the singlet oxygen degradation system, with the Fe / CNT electrode as the cathode and the Ti4O7 as the anode, so that SAs in the wastewater are initially degraded in the PMS electrolyte solution;

[0012] (2) The wastewater after preliminary degradation is injected into the sulfate radical degradation system, a constant current is passed through the sulfate radical degradation system, the Fe / CA electrode is used as the cathode, and the Ti4O7 is used as the anode, so that the wastewater continues to be degraded in the PMS electrolyte solution.

[0013] Preferably, the constant currents in step (1) and step (2) are 10-30 mA respectively, and the reaction temperatures are both room temperature.

[0014] Preferably, the concentrations of the PMS electrolyte solutions in step (1) and step (2) are 1-20 mM, and the initial pH values ​​are 2-4, respectively.

[0015] Preferably, the initial degradation time in step (1) is 1-10 min; and the continued degradation time in step (2) is 20-30 min.

[0016] Preferably, the initial concentration of SAs in wastewater in step (1) is 1-50 ppm.

[0017] Furthermore, the preparation method of the Fe / CNT electrode comprises the following steps:

[0018] S1: 10 g of melamine precursor was uniformly dispersed in 100 mL of 5 wt.% FeCl3 solution, stirred for 2 h, and then ultrasonicated for 2 h to obtain a solution;

[0019] S2: heating the solution obtained in step S1 in an oil bath at 80°C to evaporate the water, and grinding the obtained solid into powder;

[0020] S3: The powder obtained in step S2 was placed in a tube furnace and calcined in an Ar atmosphere with a flow rate of 200-300 mL / min, with the temperature increased at a rate of 2°C / min, and maintained at 180°C, 240°C, and 800°C for 2 h, 2 h, and 1 h, respectively, and then cooled to room temperature;

[0021] S4: The powder obtained in step S3 was uniformly dispersed in 100 mL of 6 mol / L HCl solution and stirred for 36 h;

[0022] S5: Filter the solution obtained in step S4 and rinse with a large amount of distilled water until the pH of the powder is neutral;

[0023] S6: drying the powder obtained in step S5 at 60° C. in vacuum for 12 h to obtain a Fe / CNT catalyst;

[0024] S7: Weigh 20 mg of the catalyst obtained in step S6, disperse it in ethanol with ultrasonic waves, and evenly drop it on carbon paper to obtain a Fe / CNT electrode.

[0025] Preferably, the thickness of the droplets dropped onto the carbon paper in step S7 is 0.1-0.5 mm.

[0026] Furthermore, the preparation method of the Fe / CA electrode comprises the following steps:

[0027] M1: resorcinol, formaldehyde, distilled water, and sodium carbonate were stirred and mixed in a molar ratio of 1:2.1:10.9:0.0008, and then ferric acetylacetonate (2%-6% by weight of the total weight of the raw materials) was added, stirred and mixed, and sealed to obtain a solution;

[0028] M2: The solution obtained in step M1 is kept at 30°C, 50°C, and 90°C for 24-72 hours to obtain a Fe / CA carbon aerogel precursor;

[0029] M3: The Fe / CA aerogel precursor obtained in step M2 was soaked in an acetone solution for 3 days and dried at room temperature for 1 day to obtain a bulk Fe / CA carbon aerogel cathode material;

[0030] M4: The block Fe / CA aerogel cathode material obtained in step M3 was placed in a tubular furnace and calcined in an Ar atmosphere with a flow rate of 200-300 mL / min. The temperature was raised to 950°C at a rate of 2.5°C / min for 2 hours, and then cooled to room temperature to obtain a Fe / CA carbon aerogel material.

[0031] M5: The Fe / CA aerogel material obtained in step M4 was placed in a tubular furnace and calcined in a CO2 atmosphere with a flow rate of 200-300 mL / min. The temperature was raised to 750°C at a rate of 2.5°C / min for 1 h, and then cooled to room temperature to obtain a Fe / CA carbon aerogel electrode.

[0032] The beneficial technical effects of the present invention are:

[0033] In most cases, PMS-mediated AOPs systems are accompanied by the generation of multiple ROS, with one or two dominant ROS species, leading to complex degradation pathways for organic pollutants. The simple coexistence or combination of these ROS species does not effectively enhance mineralization efficiency. Therefore, designing a unified electrochemical platform to achieve highly selective generation of a single ROS is a prerequisite for constructing a TRS.

[0034] The selective generation of ROS mainly depends on the electronic structure of the active site, because it determines the selective adsorption of oxygen atoms in PMS and the direction of electron transfer. 6 4s 2 ) results in the adjustability of its electronic configuration, and the unique dp hybridization mode also ensures the effective electron transfer in microenvironment engineering.

[0035] Based on this principle, the inventors used carbon nanotubes (CNT), titanium dioxide (TiO2) and carbon aerogel (CA) as carriers to adjust the electronic structure of Fe nanoparticles, activate PMS in an electrocatalytic Fenton system, and highly selectively generate three types of ROS ( 1 O2,HO · and SO4 ·– ).

[0036] Based on the selective generation of ROS in the above electrochemical system, the inventors used the TRS system formed by the connection of ROS to mineralize the representative pollutant sulfamethoxazole (SMX). A+B-TRS means that the target pollutant is first treated in system A for a certain period of time and then transferred to system B to continue the reaction. For a fair comparison, the total reaction time of TRS and single AOP system is the same, both are 30 minutes. In all TRS systems, 1 O2+SO4 ·– -TRS had the best mineralization rate, reaching 98.4% at 30 min (i.e. 3+27 min), while the mineralization rate of 1 O2 / HO · / SO4 ·– The mineralization rates of the -AOP systems were only 34.2%, 56.2% and 60.8%, respectively.

[0037] 2. Through a series of studies and experiments, the present invention has constructed an electrochemical platform in which Fe / CNT electrodes and Fe / CA electrodes are connected in series. 1 O2+SO4 ·– -TRS system can realize rapid and efficient mineralization of organic pollutants by serially reacting different reactive oxygen species according to the structural adaptability of target pollutants.

[0038] When the two electrodes are used alone, the main active species in the Fe / CNT activated PMS system are 1 O2 (i.e. 1 O2-AOP system), the degradation pathway of SMX is to destroy the SN bond. 1 Further attack by O2 produces the difficult-to-degrade intermediate product p-nitrobenzenesulfonic acid, which cannot be 1 O2 is rapidly degraded, resulting in a SMX mineralization rate of 34.2% in 30 min. The main active species in the Fe / CA activated PMS system is SO4 ·- (ie SO4 ·- -AOP system), the degradation pathway of SMX is to attack -NH2, which then further produces p-nitrobenzenesulfonic acid, which reacts with SO4 ·-The reaction kinetics are low, resulting in a SMX mineralization rate of only 60.8% within 30 minutes. Further extending the reaction time of the two systems to 60 minutes did not significantly increase the mineralization rate. During the SMX mineralization process, these two AOP systems accumulate and generate the recalcitrant intermediate p-nitrobenzenesulfonic acid, which cannot be rapidly degraded by ROS, thus hindering the complete mineralization of SMX.

[0039] The present invention uses the Fe / CNT / PMS system and the Fe / CA / PMS system in series. After optimizing the reaction time, it is found that when the reaction time of the Fe / CNT / PMS system is controlled at 3 minutes and the reaction time of the Fe / CA / PMS system is 27 minutes, the mineralization efficiency of SMX can be nearly 100% within 30 minutes. The two systems are connected in series to produce a new principle, namely, the Fe / CNT / PMS system produces 1 O2 degrades SMX within 3 minutes and converts it into the intermediate product p-aminobenzenesulfonic acid. The intermediate product is pumped into the Fe / CA system along with the reaction solution and can be converted into the generated SO4 ·- Rapid degradation and mineralization. The tandem system avoids the accumulation of the stubborn intermediate product p-nitrobenzenesulfonic acid, thereby achieving complete mineralization of SMX.

[0040] 3. Further use of the present invention 1 O2+SO4 ·– -TRS system treated a series of sulfonamide antibiotics (including: sulfamethoxazole (SMM), sulfamethoxazole (SM), sulfachloropyridazine (SCP), sulfaguanidine (SG), sulfathiazole (STZ), sulfamethizole (SMT) and sulfisoxazole (SIX)), and the mineralization rate reached 90%-100% in 30min (i.e. 3+27min). BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 SEM images of Fe / CNT, Fe / TiO2 and Fe / CA;

[0042] Figure 2 EPR spectra of Fe / CNT / PMS, Fe / TiO2 / PMS and Fe / CA / PMS systems;

[0043] Figure 3 For the present invention 1 O2+SO4 ·– -Schematic diagram of the structure of the TRS system;

[0044] Figure 4 The mineralization efficiency of SMX treated by a series of TRS and AOP systems. DETAILED DESCRIPTION

[0045] The present invention is described in detail below with reference to the accompanying drawings and embodiments. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, rather than all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0046] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0047] Example 1:

[0048] This embodiment provides specific preparation methods of Fe / CNT, Fe / TiO2 and Fe / CA electrodes.

[0049] (1) Constructing Fe / CNT cathode material, including the following steps:

[0050] S1: 10 g of melamine precursor was uniformly dispersed in 100 mL of 5 wt.% FeCl3 solution, stirred for 2 h, and then ultrasonicated for 2 h to obtain a solution;

[0051] S2: heating the solution obtained in step S1 in an oil bath at 80°C to evaporate the water, and grinding the obtained solid into powder;

[0052] S3: The powder obtained in step S2 was placed in a tube furnace and calcined in an Ar atmosphere with a flow rate of 200 mL / min, with the temperature increased at a rate of 2°C / min, and maintained at 180°C, 240°C, and 800°C for 2 h, 2 h, and 1 h, respectively, and then cooled to room temperature;

[0053] S4: The powder obtained in step S3 was uniformly dispersed in 100 mL of 6 mol / L HCl solution and stirred for 36 h;

[0054] S5: Filter the solution obtained in step S4 and rinse with a large amount of distilled water until the pH of the powder is neutral;

[0055] S6: drying the powder obtained in step S5 at 60° C. in vacuum for 12 h to obtain a Fe / CNT catalyst;

[0056] S7: Weigh 20 mg of the catalyst obtained in step S6, disperse it in ethanol with ultrasonic waves, and evenly drop it on carbon paper with a thickness of 0.3 mm to obtain a Fe / CNT electrode.

[0057] (2) Constructing Fe / TiO2 cathode material, including the following steps:

[0058] S1: Mix 0.9 g LiCl, 1.1 g KCl, 1 g commercial TiO2, and 0.3 g FeCl2·4H2O and grind them uniformly to obtain a powder;

[0059] S2: The powder obtained in step S1 was placed in a tube furnace and calcined in an Ar atmosphere with a flow rate of 200 mL / min, and the temperature was increased to 500°C at a rate of 8°C / min for 2 h, and then cooled to room temperature;

[0060] S3: Rinse the powder obtained in step S2 with distilled water;

[0061] S4: The material obtained in step S3 was vacuum dried at 60° C. for 12 h to obtain a Fe / TiO2 catalyst;

[0062] S5: Weigh 20 mg of the catalyst obtained in step S4, disperse it in ethanol with ultrasonic waves, and evenly drop it on carbon paper with a thickness of 0.3 mm to obtain a Fe / TiO2 electrode.

[0063] (3) Constructing Fe / CA cathode material, including the following steps:

[0064] S1: Resorcinol, formaldehyde, distilled water, and sodium carbonate were stirred and mixed at a molar ratio of 1:2.1:10.9:0.0008 (82.5 g of resorcinol, 108.75 mL of formaldehyde, 145 mL of water, and 15 mL of 4.2 g / L sodium carbonate solution). 3.1952 g of ferric acetylacetonate was added, stirred and mixed, and sealed to obtain a solution.

[0065] S2: The solution obtained in step S1 was first kept at 30°C for 24 hours, then kept at 50°C for 24 hours, and finally kept at 90°C for 72 hours to obtain a Fe / CA carbon aerogel precursor;

[0066] S3: soaking the Fe / CA carbon aerogel precursor obtained in step S2 in an acetone solution for 3 days and drying it at room temperature for 1 day to obtain a bulk Fe / CA carbon aerogel cathode material;

[0067] S4: placing the block Fe / CA aerogel cathode material obtained in step S3 in a tubular furnace, calcining it in an Ar atmosphere with a flow rate of 200-300 mL / min, heating it to 950° C. at a rate of 2.5° C. / min, calcining it for 2 h, and then cooling it to room temperature to obtain a Fe / CA aerogel material;

[0068] S5: The Fe / CA aerogel material obtained in step S4 was placed in a tubular furnace and calcined in a CO2 atmosphere with a flow rate of 200 mL / min. The temperature was raised to 750°C at a rate of 2.5°C / min for 1 h, and then cooled to room temperature to obtain a Fe / CA aerogel electrode.

[0069] The prepared Fe / CNT, Fe / TiO2 and Fe / CA electrodes were characterized by scanning electron microscopy (SEM), as shown in Figure 2. Figure 1 As shown in (ac), Fe / CNT is a hollow bamboo-shaped carbon nanotube with a diameter of 100-150nm; Fe / TiO2 is a uniform rectangular TiO2 particle; and Fe / CA is a three-dimensional network structure composed of interconnected microspheres.

[0070] Example 2:

[0071] The Fe / CNT, Fe / TiO2 and Fe / CA in Example 1 were used as electrochemical cathodes, and singlet oxygen ( 1 O2), sulfate radical (SO4 ·– ) and hydroxyl radicals (HO · ) was used for detection. 100 mM TEMP was used as the capture agent and 1 O2 forms a complex TEMP- 1 O2; 0.22 mol L -1 DMPO is used as a capture agent to react with SO4 ·– and HO · Formation of complex DMPO-SO4 ·– and DMPO-HO · The EPR resonance frequency was set to 9.85 GHz, and the peristaltic pump, electrochemical workstation, and EPR spectrometer were controlled via RS485 serial communication to achieve coordination between the electrochemical sequence and the EPR two-dimensional time series.

[0072] The ROS generated by activating 5 mM potassium peroxymonosulfate (PMS) using Fe / CNT, Fe / TiO2 and Fe / CA as cathodes were detected by electron paramagnetic resonance spectroscopy (EPR). Figure 2 As shown in the figure, it can be seen that the Fe / CNT / PMS system only detects 1 O2; SO4 can be detected in both Fe / TiO2 / PMS and Fe / CA / PMS systems ·– and HO · , but the HO produced by the Fe / TiO2 / PMS system · The signal intensity is much higher than SO4 ·– ; The SO4 produced by Fe / CA / PMS system ·– The signal strength is much higher than HO · The EPR test results show that the main active species of Fe / CNT / PMS, Fe / TiO2 / PMS and Fe / CA / PMS systems are1 O2, HO · and SO4 ·– .

[0073] Example 3:

[0074] The Fe / CNT / PMS, Fe / TiO2 / PMS and Fe / CA / PMS systems in Example 2 were connected in series to form a TRS, and the ability of a series of TRS systems and a single ROS-AOP system to mineralize sulfamethoxazole SMX was evaluated.

[0075] After connecting Fe / CNT / PMS, Fe / TiO2 / PMS and Fe / CA / PMS systems in series, six TRS systems were obtained: Fe / CNT+Fe / CA( 1 O2+SO4 ·– -TRS)、Fe / CA+Fe / CNT(SO4 ·– + 1 O2-TRS)、Fe / CNT+Fe / TiO2( 1 O2+HO · -TRS)、Fe / TiO2+Fe / CNT(HO · + 1 O2-TRS)、Fe / CA+Fe / TiO2(SO4 ·– +HO · -TRS)、Fe / TiO2+Fe / CA(HO · +SO4 ·– -TRS).

[0076] The specific structure of TRS formed in series is as follows 1 O2+SO4 ·– -TRS system series platform as an example, Figure 3 As shown, it includes a water inlet tank, a PMS solution tank, a singlet oxygen degradation system, a sulfate radical degradation system and a water outlet tank which are connected in sequence by pipelines.

[0077] The wastewater to be treated containing SAs is stored in the water inlet tank, which is mixed with the PMS electrolyte solution in the PMS solution tank and then pumped into the water inlet of the singlet oxygen degradation system; after preliminary degradation in the singlet oxygen degradation system, the wastewater is injected into the water inlet of the sulfate free radical degradation system from the water outlet of this system; after further degradation in the sulfate free radical degradation system, the wastewater is injected into the water outlet tank from the water outlet of this system.

[0078] The singlet oxygen degradation system uses Fe / CNT as the cathode and commercial Ti4O7 as the anode; the sulfate radical degradation system uses Fe / CA as the cathode and commercial Ti4O7 as the anode. Both systems can use the same DC power supply for the cathode and anode, with constant current applied sequentially during the initial and subsequent degradation processes.

[0079] All six systems used a two-electrode potentiostat as a DC power source, applying a constant current of 20 mA. SMX and SAs (40 mL, 10 ppm) were degraded in a 5 mM PMS solution over a total degradation time of 30 minutes at a temperature of 25°C and an initial pH of 3.

[0080] The processing results are as follows Figure 4 As shown, 1 O2+SO4 ·– The TRS system achieved 98.4% mineralization of sulfamethoxazole SMX within 30 minutes, which was higher than that of other TRS systems. 1 O2 / HO · / SO4 ·– The mineralization rates of the -AOP systems were only 34.2%, 56.2% and 60.8%, respectively.

[0081] Further use 1 O2+SO4 ·– -TRS system treated a series of sulfonamide antibiotics (sulfamonomethiozine (SMM), sulfamethoxazole (SM), sulfachloropyridazine (SCP), sulfaguanidine (SG), sulfathiazole (STZ), sulfamethizole (SMT) and sulfisoxazole (SIX)), and the mineralization rate reached 90-100% within 30 minutes (initial degradation for 3 minutes and continued degradation for 27 minutes).

[0082] To optimize the degradation time, we first adjusted the singlet oxygen system time while keeping the sulfate radical system time constant. The initial degradation and continued degradation times were set to 1+27, 3+27, 5+27, and 10+27 (minutes) for the combined degradation of SMX. The results showed that the mineralization rate was optimal at 3+27 minutes. Then, we adjusted the sulfate radical system time while keeping the singlet oxygen system time constant. The initial degradation and continued degradation times were set to 3+22, 3+25, 3+27, and 3+30 for the combined degradation of SMX. The results showed that the mineralization rate was optimal at 3+27 minutes.

[0083] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for the efficient mineralization of organic pollutants by series electrochemical reaction, characterized in that: The method is based on 1 O2+SO4 - •-TRS system, which uses a two-electrode DC power supply and includes a singlet oxygen degradation system and a sulfate radical degradation system in sequence; The singlet oxygen degradation system uses a Fe / CNT electrode as a cathode and Ti4O7 as an anode; the sulfate radical degradation system uses a Fe / CA electrode as a cathode and Ti4O7 as an anode.

2. The method according to claim 1, characterized in that The following steps are involved: (1) Wastewater containing sulfonamide antibiotics SAs and potassium peroxymonosulfonate (PMS) electrolyte solution are mixed and injected into the singlet oxygen degradation system. A constant current is passed through the singlet oxygen degradation system, with the Fe / CNT electrode as the cathode and the Ti4O7 as the anode, so that SAs in the wastewater are initially degraded in the PMS electrolyte solution; (2) The wastewater after preliminary degradation is injected into the sulfate radical degradation system, a constant current is passed through the sulfate radical degradation system, the Fe / CA electrode is used as the cathode, and the Ti4O7 is used as the anode, so that the wastewater continues to be degraded in the PMS electrolyte solution.

3. The method according to claim 2, characterized in that The constant currents in step (1) and step (2) are 10-30 mA respectively, and the reaction temperatures are both room temperature.

4. The method according to claim 2, characterized in that The concentrations of the PMS electrolyte solutions in step (1) and step (2) are 1-20 mM, and the initial pH values ​​are 2-4, respectively.

5. The method according to claim 2, characterized in that The initial degradation time in step (1) is 1-10 minutes; the continued degradation time in step (2) is 20-30 minutes.

6. The method according to claim 2, characterized in that The initial concentration of SAs in wastewater in step (1) is 1-50 ppm.

7. The method according to claim 1 or 2, characterized in that The preparation method of the Fe / CNT electrode comprises the following steps: S1: 10 g of melamine precursor was uniformly dispersed in 100 mL of 5 wt.% FeCl3 solution, stirred for 2 h, and then ultrasonicated for 2 h to obtain a solution; S2: heating the solution obtained in step S1 in an oil bath at 80°C to evaporate the water, and grinding the obtained solid into powder; S3: The powder obtained in step S2 was placed in a tube furnace and calcined in an Ar atmosphere with a flow rate of 200-300 mL / min, with the temperature increased at a rate of 2°C / min, and maintained at 180°C, 240°C, and 800°C for 2 h, 2 h, and 1 h, respectively, and then cooled to room temperature; S4: The powder obtained in step S3 was uniformly dispersed in 100 mL of 6 mol / L HCl solution and stirred for 36 h; S5: Filter the solution obtained in step S4 and rinse with a large amount of distilled water until the pH of the powder is neutral; S6: drying the powder obtained in step S5 at 60° C. in vacuum for 12 h to obtain a Fe / CNT catalyst; S7: Weigh 20 mg of the catalyst obtained in step S6, disperse it in ethanol with ultrasonic waves, and evenly drop it on carbon paper to obtain a Fe / CNT electrode.

8. The method according to claim 1 or 2, characterized in that The preparation method of the Fe / CA electrode comprises the following steps: M1: resorcinol, formaldehyde, distilled water, and sodium carbonate were stirred and mixed in a molar ratio of 1:2.1:10.9:0.0008, and then ferric acetylacetonate (2%-6% by weight of the total weight of the raw materials) was added, stirred and mixed, and sealed to obtain a solution; M2: The solution obtained in step M1 is kept at 30°C, 50°C, and 90°C for 24-72 hours to obtain a Fe / CA carbon aerogel precursor; M3: The Fe / CA aerogel precursor obtained in step M2 was soaked in an acetone solution for 3 days and dried at room temperature for 1 day to obtain a bulk Fe / CA carbon aerogel cathode material; M4: The block Fe / CA aerogel cathode material obtained in step M3 was placed in a tubular furnace and calcined in an Ar atmosphere with a flow rate of 200-300 mL / min. The temperature was raised to 950°C at a rate of 2.5°C / min for 2 hours, and then cooled to room temperature to obtain a Fe / CA carbon aerogel material. M5: The Fe / CA aerogel material obtained in step M4 was placed in a tubular furnace and calcined in a CO2 atmosphere with a flow rate of 200-300 mL / min. The temperature was raised to 750°C at a rate of 2.5°C / min for 1 h, and then cooled to room temperature to obtain a Fe / CA carbon aerogel electrode.

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