Electrode material for H-type electrolytic cell and method for simultaneously degrading typical deficient / abundant explosive wastewater

Abstract

The application discloses an electrode material for H-type electrolytic cell, comprising a cathode material and an anode material. The application also discloses a method for simultaneously degrading typical deficient / electron-rich explosive wastewater, comprising: using an H-type electrolytic cell, using a proton membrane to separate a cathode chamber and an anode chamber, adding an electron-deficient organic pollutant aqueous solution into the cathode chamber, adding an electron-rich organic pollutant aqueous solution and a peroxymonosulfate into the anode chamber, using the cathode material and the anode material as a cathode and an anode respectively, using SO4 2‑ , HCO3 ‑ , Cl ‑ , NO3 ‑ or HPO4 2‑ as an electrolyte, and simultaneously degrading the electron-deficient organic pollutant and the electron-rich organic pollutant under the action of an external current. The application combines a heterogeneous electro-Fenton system and an anode oxidation system, can simultaneously degrade an electron-deficient explosive such as HMX and an electron-rich explosive such as DNAN, and keeps a high degradation rate under the environment of different electrolytes and a wide pH range.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical materials and explosive wastewater environmental treatment, and relates to an electrode material for H-type electrolytic cells, specifically to a cathode material and an anode material for H-type electrolytic cells, and a method for applying the cathode material and anode material to H-type electrolytic cells to simultaneously degrade typical electron-deficient / electron-rich explosive wastewater. Background Technology

[0002] Explosives, as high-energy organic compounds, can be used for both military and peaceful purposes, such as nuclear devices, rocket propellants, and rocket fuel. The production, transportation, and use of explosives leave large amounts of residues in water bodies, posing a potential threat to human health and ecological safety. 2,4-Dinitroanisole (DNAN), a typical electron-rich compound, is a type of insensitive munition used in the defense industry. Although its water solubility is very low (approximately 276 mg / L at room temperature), it can form rod-shaped crystals at high concentrations. When adsorbed onto clay and organic matter in soil, it can have a significant environmental impact. Currently, methods for removing HMX and DNAN include photocatalysis and biodegradation, but all suffer from long reaction times, low removal efficiency, and incomplete degradation. Therefore, exploring wastewater treatment technologies that can effectively and safely degrade explosives remains a challenging task and is crucial for public health and environmental protection.

[0003] Electrochemical advanced oxidation processes (AEs) can generate highly oxidizing free radicals (such as ·OH) and have become a promising method for treating organic pollutants in wastewater. Among them, heterogeneous electro-Fenton (HEF) and anodic oxidation (AO) are the most representative electrochemical AEs. HEF achieves effective degradation of organic pollutants by utilizing the cathode to generate H2O2 and activate it to produce ·OH. Although HEF has advantages such as ease of operation and fast reaction kinetics, the electrodes may generate metallic sludge during H2O2 production; in addition, once the chemical oxygen demand reaches a certain removal rate, further degradation of organic matter becomes challenging, leading to excessive consumption of H2O2 and waste of resources. Anodic oxidation degrades organic matter in wastewater by directly or indirectly generating ·OH through electrode oxidation or surface catalysis, but its limitations lie in high energy consumption and prolonged treatment time. It is foreseeable that if a dual degradation system combining HEF and AO can be manufactured, the complementarity of heterogeneous electro-Fenton and anodic oxidation can be achieved, and the synergistic removal of multiple pollutants can be realized. However, the following challenges remain: 1. Do the electrodes in the two electrode chambers need to be identical? If they are the same, it is necessary to consider whether the anode material, while performing well, is also suitable for the cathode, and vice versa. If they are different, it is necessary to consider how each electrode addresses the HEF and AO issues. 2. It is necessary to simultaneously address the issues of cathode metal sludge and high anode energy consumption (examine cycle stability, etc.). Summary of the Invention

[0004] The purpose of this invention is to address the difficulties in treating explosive wastewater, the limitations of existing technologies that can only degrade single electron-deficient or electron-rich compounds, and the safety concerns and environmental pollution caused by the potential for explosions due to the seepage of explosive wastewater into the soil. This invention provides a cathode and anode material for use in an H-type electrolytic cell. The cathode and anode materials are used as the cathode and anode of the H-type electrolytic cell, respectively, and separated by a proton exchange membrane. This combines HEF and AO, enabling the simultaneous degradation of typical explosive-deficient / electrode-rich wastewater. This not only solves the shortcomings of existing technologies that can only degrade single types of wastewater but also addresses environmental pollution and the difficulty in degrading explosive wastewater, demonstrating promising application prospects in wastewater treatment.

[0005] The technical solution adopted in this invention is:

[0006] An electrode material for an H-type electrolytic cell, comprising a cathode material and an anode material;

[0007] The cathode material is obtained by immersing copper foam in a mixed aqueous solution of NaOH and ammonium persulfate ((NH4)2S2O8) to obtain copper foam with uniformly grown Cu(OH)2 nanoneedle arrays. Then, the copper foam with grown Cu(OH)2 nanoneedle arrays is immersed in an aqueous solution of Mn(NO3)2·4H2O to react. Ce(NO3)2·6H2O is then added to continue the reaction. The mixture is then transferred to an aqueous solution of NaOH for treatment and dried to obtain the cathode material precursor. The cathode material precursor is then calcined in an air atmosphere to obtain the cathode material (denoted as CeO2-MnO2@CuO NWs / CF).

[0008] The anode material is prepared by adding Co(NO3)2·6H2O and polyvinylpyrrolidone to a mixed solvent of water and ethylene glycol, then adding sodium thiosulfate to react and obtain a precursor solution. Activated carbon fiber cloth is then immersed in the precursor solution and heat-treated at 140–160°C for 10–12 hours. After cooling to room temperature, the activated carbon fiber cloth is removed, washed with deionized water, and dried to obtain the anode material (denoted as CoS2@CC).

[0009] Preferably, the cathode material is prepared by the following method: at room temperature, activated copper foam is immersed in a mixed aqueous solution of NaOH and ammonium persulfate for 0.5-1 h, and Cu(OH)2 nanoneedle arrays are uniformly grown on the copper foam to obtain copper foam with Cu(OH)2 nanoneedle arrays; the copper foam with Cu(OH)2 nanoneedle arrays is immersed in an aqueous solution of Mn(NO3)2·4H2O and reacted at 70-85°C for 0.8-1.2 h, then Ce(NO3)2·6H2O is added and reacted at 70-85°C for 0.8-1.2 h, the copper foam is transferred to an aqueous solution of NaOH and soaked at room temperature for 30-40 minutes, the copper foam is taken out, rinsed with deionized water to remove surface impurities, and dried to obtain the cathode material precursor; the cathode material precursor is calcined in air at 300-350°C for 2-2.5 h to obtain the cathode material (denoted as CeO2-MnO2@CuO NWs / CF).

[0010] The copper foam is 1 cm thick. 2 Copper foam sheets.

[0011] The activation process involves immersing the copper foam in acetone, ethanol, and acetic acid for 15 minutes each, and then rinsing it with plenty of deionized water until the washing solution is neutral (pH≈7).

[0012] In the mixed aqueous solution of NaOH and (NH4)2S2O8, the concentration of NaOH is 2-2.5 mol / L and the concentration of (NH4)2S2O8 is 0.10-0.16 mol / L.

[0013] Preferably, in the mixed aqueous solution of NaOH and (NH4)2S2O8, the concentration of NaOH is 2.5 mol / L and the concentration of (NH4)2S2O8 is 0.13 mol / L.

[0014] Preferably, at room temperature, the activated copper foam is immersed in a mixed aqueous solution of NaOH and ammonium persulfate for 0.5 to 1 hour, then removed and dried at 60°C for 10 hours to obtain copper foam with Cu(OH)2 nanoneedle arrays grown on it.

[0015] The concentration of the Mn(NO3)2·4H2O aqueous solution is 0.1–0.166 mol / L; the molar ratio of Mn(NO3)2·4H2O to Ce(NO3)2·6H2O is 1:3–3:3, preferably 2:3.

[0016] Preferably, the copper foam is removed, rinsed with deionized water, and dried at 50-70°C for 8-12 hours to obtain the cathode material precursor.

[0017] Preferably, the cathode material precursor is heated in an air atmosphere at a rate of 2.5–3.5 °C / min. -1 The temperature is raised to 300-350℃ and calcined at 300-350℃ for 2-2.5 hours to obtain the cathode material.

[0018] Preferably, the anode material is prepared by the following method: Co(NO3)2·6H2O and polyvinylpyrrolidone are added to a mixed solvent of ethylene glycol and mixed evenly. Sodium thiosulfate is added, and the mixture is reacted at room temperature for 1.5 to 2 hours. The mixture is then ultrasonically treated for 30 to 40 minutes to obtain a dispersion. Activated carbon fiber cloth is immersed in the dispersion and heat-treated at 140 to 160°C for 12 hours. The activated carbon fiber cloth is then removed, washed with deionized water, and dried at 50 to 70°C for 8 to 12 hours to obtain the anode material (denoted as CoS2@CC).

[0019] The mass ratio of Co(NO3)2·6H2O to polyvinylpyrrolidone is 0.95:1 to 1:1, preferably 0.97:1.

[0020] The ratio of Co(NO3)2·6H2O to water is 1:30 to 1:35 g / mL.

[0021] The volume ratio of water to ethylene glycol is 1:1.

[0022] The molar ratio of Co(NO3)2·6H2O to sodium thiosulfate is 0.5:1 to 0.55:1.

[0023] The area of ​​the activated carbon fiber cloth is 1 cm². 2 .

[0024] Another object of the present invention is to provide a method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater, comprising: using an H-type electrolytic cell, separating the cathode chamber and the anode chamber with a proton exchange membrane, adding an aqueous solution of electron-deficient organic pollutants to the cathode chamber, adding an aqueous solution of electron-rich organic pollutants and persulfate to the anode chamber, using the aforementioned cathode material (CeO2-MnO2@CuO NWs / CF) and the aforementioned anode material (CoS2@CC) as the cathode and anode respectively, and using SO42- as the anode. 2- HCO3 - Cl - NO3 - or HPO4 2- It acts as an electrolyte, simultaneously degrading both electron-deficient and electron-rich organic pollutants under the action of an applied current.

[0025] The area of ​​the cathode is 1 cm². 2 The area of ​​the anode is 1 cm². 2The applied current density is 5-20 mA, preferably 10-15 mA, and most preferably 10 mA.

[0026] The initial pH of the aqueous solution of electron-deficient organic pollutants in the cathode chamber is 3-11, preferably 5-7, and more preferably 5; the initial pH of the aqueous solution of electron-rich organic pollutants in the anode chamber is 3-11, preferably 7-11, and more preferably 9.

[0027] The final concentration of the permonosulfate (2KHSO5·KHSO4·K2SO4, also known as PMS) is 20-25 mg / L, and the permonosulfate is used as an auxiliary activator for the anode material.

[0028] The concentration of the electrolyte is 0.050–0.055 mol / L.

[0029] Preferably, the electrolyte is SO4. 2- Or NO3 - .

[0030] Most preferably, the electrolyte is SO4. 2- .

[0031] The concentration of the aqueous solution of the electron-deficient organic pollutant is 6–20 mg / L, and the concentration of the aqueous solution of the electron-rich organic pollutant is 10–60 mg / L.

[0032] The electron-deficient organic pollutant is at least one of tetramethylenetetranitroamine (HMX), cyclotrimethylenetrinitramine (RDX), and hexanitrohexaazaisowulzane (CL-20).

[0033] The electron-rich organic pollutant is at least one of trinitrotoluene (TNT), disodium azotetrazol (Na2AzTz), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine (NQ).

[0034] The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater as described in this invention further includes: under the influence of an electric current and the action of a proton exchange membrane, hydrogen ions in the anode chamber are transported to the cathode chamber, balancing the pH values ​​of the cathode and anode chambers, maximizing the generation of free radicals, and simultaneously achieving rapid and efficient degradation of organic pollutants in both polar regions.

[0035] The beneficial effects of this invention are:

[0036] This invention combines a heterogeneous electro-Fenton (HEF) system and an anodic oxidation (AO) system, with HEF corresponding to the cathode chamber and AO corresponding to the anode chamber. It can simultaneously degrade electron-deficient explosives such as HMX and electron-rich explosives such as DNAN. Using a pn heterojunction CeO2-MnO2@CuO / CF as the cathode material enhances interfacial charge transfer and charge carrier mobility, thereby increasing the degradation rate and exhibiting significant redox performance. In the HEF system, the HMX removal rate reaches as high as 95.1%; in the anode chamber, Co... 2+ As a beneficial active site, it achieves a 100% removal rate of DNAN.

[0037] This invention demonstrates the ability to maintain a high degradation rate under different electrolyte environments and a wide pH range; H * and 1 O2 is the main contributor to the HEF system, while ·OH and 1 O2 is dominant in the AO system.

[0038] This invention solves the problems of difficult treatment of explosive wastewater, degradation of single wastewater, and environmental pollution caused by safety and toxicity. It provides an innovative dual degradation system for the simultaneous removal of electron-deficient / electron-rich explosives and broadens the technical framework for wastewater treatment by electrochemical advanced oxidation. Attached Figure Description

[0039] Figure 1 These are scanning electron microscope (SEM) images and transmission electron microscope (TEM) elemental diagrams of the cathode material (CeO2-MnO2@CuO NWs / CF); a is an SEM image of copper foam with a Cu(OH)2 nanoneedle array; b is an SEM image of Mn and Ce elements in the cathode material; c is a high-resolution TEM image of the cathode material; d is a diagram of the elemental distribution of the cathode material; e is a TEM image of the Cu element content in the cathode material; f is a TEM image of the Mn element content in the cathode material; g is a TEM image of the Ce element content in the cathode material; h is a TEM image of the O element content in the cathode material; and i is a high-resolution TEM image of the heterostructure formed at the CuO and MnO2 interface.

[0040] Figure 2 These are scanning electron microscope (SEM) images and transmission electron microscope (TEM) images of the anode material (CoS2@CC). Among them, a is the SEM image of the anode material (scale bar 5 μm), b is the SEM image of the anode material (scale bar 50 nm), c is the crystal lattice diagram of CoS2, d is the TEM image of the Co element content in the anode material, e is the TEM image of the S element content in the anode material, and f is the TEM image of the O element content in the anode material.

[0041] Figure 3The degradation effect of cathode materials prepared with different molar ratios of Mn and Ce on HMX is shown.

[0042] Figure 4 The figures show the linear current-voltage curves (a) and impedance diagrams (b) for different cathode materials.

[0043] Figure 5 The figures (a) and (b) are linear voltammetry curves and impedance diagrams for different anode materials; where C represents activated carbon fiber cloth.

[0044] Figure 6 This is a diagram of the electron transfer mechanism in the CeO2-MnO2@CuO NWs / CF heterojunction.

[0045] Figure 7 It describes the effect of applied current density on the degradation of HMX and DNAN.

[0046] Figure 8 The effects of initial pH of HMX solution (a), initial pH of DNAN solution (b), and anions (c) on degradation are shown.

[0047] Figure 9 It is a pathway diagram simulating the catalytic reaction that generates free radicals in the actual degradation process.

[0048] Figure 10 These are free radicals detected during the cathodic degradation of HMX; where a is the capture diagram of H* and ·OH during the reaction, b is the free radical capture diagram at different reaction times, and c is the free radical capture diagram during the reaction. 1 O2 capture graph.

[0049] Figure 11 These are free radicals detected during the anodic degradation of DNAN; where a represents the free radicals generated during the reaction, such as ·OH and O2·. - and SO4 ·- The capture image, b is the reaction process 1 O2 capture graph.

[0050] Figure 12 This is a graph showing the degradation effect of other electron-deficient and electron-rich organic pollutants; where a is a comparison graph of the degradation effect of electron-deficient organic pollutants and the total organic carbon removal rate, and b is a graph of the degradation effect of electron-rich organic pollutants and the total organic carbon removal rate.

[0051] Figure 13 These are test results for the cyclic stability of the cathode and anode materials. Detailed Implementation

[0052] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0053] Example 1

[0054] Preparation of cathode material: Copper foam was cut into thin slices (1 cm long, 1 cm wide, and 0.1 cm thick), and soaked in acetone, ethanol, and acetic acid for 15 minutes each, respectively. Then, it was washed with deionized water until the pH of the washing solution was approximately 7. At room temperature, the activated copper foam was soaked in a mixed solution of NaOH and (NH4)2S2O8 (prepared with deionized water, with NaOH concentration of 2.5 mol / L and (NH4)2S2O8 concentration of 0.13 mol / L) for 0.5 h, and Cu(OH)2 nanoneedle arrays were uniformly grown on the copper foam. The copper foam was then removed and dried at 60 °C for 10 h to obtain copper foam with Cu(OH)2 nanoneedle arrays grown on it. Under slow magnetic stirring, copper foam with Cu(OH)₂ nanoneedle arrays was immersed in a 0.133 mol / L Mn(NO₃)₂·4H₂O aqueous solution and reacted at 80°C for 1 h. Ce(NO₃)₂·6H₂O was then added to bring the final concentration to 0.2 mol / L (Mn to Ce molar ratio approximately 2:3), and the reaction was continued at 80°C for 1 h. The resulting solid was transferred to a 1 mol / L NaOH aqueous solution and reacted at room temperature for 30 min. The electrode was then removed with tweezers, and the sample was rinsed with deionized water to remove surface impurities. It was then dried at 60°C for 10 h. Finally, the sample was heated in air at a rate of 3°C / min. -1 The temperature was raised to 350℃ and calcined at 350℃ for 2 hours to obtain the cathode material, denoted as CeO2-MnO2@CuO NWs / CF.

[0055] The structural characteristics of the cathode material were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. The results are shown in [Figure 1]. Figure 1 . Figure 1 a is a scanning electron microscope image of copper foam with Cu(OH)2 nanoneedle arrays grown on it; Figure 1 b is a scanning electron microscope image of the cathode material with added Mn and Ce elements. It can be seen that the surface of the copper foam nanoarray is covered with small particles, indicating that Mn and Ce elements are uniformly distributed on the surface of the copper foam nanoarray. Figure 1 c. Figure 1 d represents the transmission electron microscope (TEM) image and the elemental scan image of the cathode material, respectively. Figure 1 e Figure 1 f、 Figure 1 g、 Figure 1 h represents the content of Cu, Mn, Ce, and O elements in the cathode material CeO2-MnO2@CuO NWs / CF under transmission electron microscopy, indicating that Mn and Ce elements were successfully loaded onto the Cu surface. Obvious heterojunction striations are visible at the interface between CuO and CeO2-MnO2. Figure 1i) This confirms that CeO2-MnO2@CuO NWs / CF possesses a heterojunction nanostructure. It also demonstrates that the present invention requires immersing copper foam with Cu(OH)2 nanoneedle arrays in an aqueous solution of Mn(NO3)2·4H2O, followed by the addition of Ce(NO3)2·6H2O to react in order to obtain a heterojunction nanostructure. This avoids the situation where "immersing copper foam with Cu(OH)2 nanoneedle arrays in a mixed aqueous solution of Mn(NO3)2·4H2O and Ce(NO3)2·6H2O only generates small MnCe-doped particles and cannot obtain a heterojunction morphology from the inside out."

[0056] Preparation of anode material: 0.582 g Co(NO3)2·6H2O and 0.6 g polyvinylpyrrolidone (average molecular weight 58000) were added to a mixed solvent of 20 mL water and 20 mL ethylene glycol. After mixing evenly, 0.62 g sodium thiosulfate was added, and the mixture was reacted at room temperature for 2 hours. Then, it was sonicated for 30 minutes to ensure full dispersion, which is the precursor solution. The precursor solution was transferred to a PTFE reactor, and activated carbon fiber cloth (1 cm long, 1 cm wide, and 0.1 cm thick) was immersed in the dispersion solution and treated at 160 °C for 12 hours. After cooling to room temperature, the activated carbon fiber cloth was removed, washed with deionized water, and then dried at 60 °C for 12 hours to obtain the anode material, labeled CoS2@CC.

[0057] The structural characteristics of the anode material were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. The results are shown in [Figure 1]. Figure 2 . Figure 2 a- Figure 2 b is a scanning electron microscope image of the anode material, showing that cobalt disulfide (CoS2) nanoparticles are uniformly anchored on the activated carbon fiber cloth. The cobalt disulfide nanoparticles appear as small spherical particles with an average size of about 170 nm. Figure 2 c is the lattice diagram of CoS2. Figure 2 d、 Figure 2 e represents the Co and S element content in the anolyte CoS2@CC under transmission electron microscopy, indicating that Co and S elements were successfully loaded onto the carbon fiber cloth surface; furthermore... Figure 2 The disordered distribution of oxygen f confirms that no cobalt oxide was generated during the preparation of the anode material; only CoS2 was generated. The above characterization results demonstrate that the present invention successfully prepared the anode material CoS2@CC.

[0058] Example 2

[0059] The effect of different molar ratios of Mn and Ce on the degradation of HMX

[0060] Referring to Example 1, "Preparation of Cathode Material", the concentration of the Mn(NO3)2·4H2O aqueous solution was fixed at 0.133 mol / L. The amount of Ce(NO3)2·6H2O added was adjusted so that the molar ratio of Mn to Ce was approximately 1:3 and 3:3, respectively. All other aspects were the same as in Example 1. The resulting cathode materials were denoted as CeO2-MnO2-1:3@CuO NWs / CF and CeO2-MnO2-3:3@CuONWs / CF, respectively.

[0061] Cathode materials prepared with different molar ratios of Mn and Ce were used as cathodes, and CoS2@CC prepared in Example 1 was used as an anode to investigate the electrocatalytic degradation of organic pollutants.

[0062] Weigh 10 mg of HMX into a 1 L volumetric flask and titrate to the mark with deionized water to obtain an HMX solution with a concentration of 10 mg / L. Weigh 15 mg of DNAN into a 1 L volumetric flask and titrate to the mark with deionized water to obtain a DNAN solution with a concentration of 15 mg / L. Adjust the initial pH of both the HMX and DNAN solutions to 7 using 0.1 mmol / L sulfuric acid and 0.1 mmol / L sodium hydroxide. Use the anode material (CoS2@CC) prepared in Example 1 as the anode (anode area 1 cm²) in the anode chamber of the H-type electrolytic cell. 2 The cathode material prepared in the cathode chamber with different molar ratios of Mn and Ce is used as the cathode (cathode area 1 cm²). 2 The two electrode chambers are separated by an N117 proton exchange membrane. 50 mL of HMX solution is placed in the cathode chamber of the H-type electrolytic cell, and 50 mL of DNAN solution is placed in the anode chamber. Persulfate (2KHSO5·KHSO4·K2SO4, also known as PMS, final concentration 20 mg / L) is added to the anode chamber as an auxiliary activator for the anode material. The electrolyte in both the cathode and anode chambers is 0.05 mol / L Na2SO4. After energizing, approximately 2 mL of solution is taken from the cathode chamber every 10 min using a syringe, filtered through a 0.22 μm polyethersulfone membrane, and the remaining free radicals are quenched with 0.5 mL of methanol. Similarly, approximately 2 mL of solution is taken from the cathode chamber every 1 min using a syringe, filtered through a 0.22 μm polyethersulfone membrane, and the remaining free radicals are quenched with 0.5 mL of methanol. The concentration of HMX was detected at 254 nm and the concentration of DNAN was detected at 280 nm using a high-performance liquid chromatography (HPLC) instrument with a UV-Vis detector. A reversed-phase C18 column (5 μm, 4.6 mm × 250 mm) was used, with water and methanol (30%:70%) as the mobile phase at a flow rate of 1 mL / min. The peak areas of the solutions before and after degradation were measured by HPLC, and the ratio between the two was calculated to determine the degradation rate of HMX.

[0063] like Figure 3As shown, cathode materials prepared with a molar ratio of Mn to Ce of approximately 1:3 to 3:3 all exhibit good degradation effects on HMX, with the cathode material prepared with a molar ratio of Mn to Ce of 2:3 showing the best degradation effect.

[0064] Comparative Example 1

[0065] Preparation of CuO NWs / CF: Copper foam was cut into thin slices (1 cm long, 1 cm wide, and 0.1 cm thick), and soaked in acetone, ethanol, and acetic acid for 15 minutes each, then rinsed with deionized water. At room temperature, the activated copper foam was soaked in a mixed solution of NaOH and (NH4)2S2O8 (prepared with deionized water, NaOH concentration 2.5 mol / L, (NH4)2S2O8 concentration 0.13 mol / L) for 0.5 h. The electrode sheet was removed with tweezers, and the sample was rinsed with deionized water to remove surface impurities. It was then dried at 60 °C for 10 h. Finally, in an air atmosphere, the sample was heated at a rate of 3 °C / min. -1 The temperature was raised to 350℃ and calcined at 350℃ for 2 hours to obtain the cathode material, denoted as CuO NWs / CF.

[0066] Preparation of CeO2@CuO NWs / CF: Copper foam was cut into thin slices (1 cm long, 1 cm wide, and 0.1 cm thick), and soaked in acetone, ethanol, and acetic acid for 15 minutes each, then washed with deionized water. At room temperature, the activated copper foam was soaked in a mixed solution of NaOH and (NH4)2S2O8 (prepared with deionized water, with NaOH concentration of 2.5 mol / L and (NH4)2S2O8 concentration of 0.13 mol / L) for 0.5 h, and Cu(OH)2 nanoneedle arrays were uniformly grown on the copper foam. The copper foam was then removed and dried at 60 °C for 10 h to obtain copper foam with Cu(OH)2 nanoneedle arrays. Under slow magnetic stirring, copper foam with Cu(OH)₂ nanoneedle arrays was immersed in a 0.2 mol / L Ce(NO₃)₂·6H₂O aqueous solution and reacted at 80 °C for 1 h. The resulting solid was then transferred to a 1 mol / L NaOH aqueous solution and reacted at room temperature for 30 min. The electrode was removed with tweezers, and the sample was rinsed with deionized water to remove surface impurities. It was then dried at 60 °C for 10 h. Finally, the sample was heated in air at a rate of 3 °C / min. -1 The temperature was raised to 350℃ and calcined at 350℃ for 2 hours to obtain the cathode material, denoted as CeO2@CuO NWs / CF.

[0067] Preparation of MnO2@CuO NWs / CF: Copper foam was cut into thin slices (1 cm long, 1 cm wide, and 0.1 cm thick), and soaked in acetone, ethanol, and acetic acid for 15 minutes each, then washed with deionized water. At room temperature, the activated copper foam was soaked in a mixed solution of NaOH and (NH4)2S2O8 (prepared with deionized water, with NaOH concentration of 2.5 mol / L and (NH4)2S2O8 concentration of 0.13 mol / L) for 0.5 h, and Cu(OH)2 nanoneedle arrays were uniformly grown on the copper foam. The foam was then removed and dried at 60 °C for 10 h to obtain copper foam with Cu(OH)2 nanoneedle arrays. Under slow magnetic stirring, copper foam with Cu(OH)₂ nanoneedle arrays was immersed in a 0.133 mol / L Mn(NO₃)₂·4H₂O aqueous solution and reacted at 80 °C for 1 h. The resulting solid was then transferred to a 1 mol / L NaOH aqueous solution and reacted at room temperature for 30 min. The electrode was removed with tweezers, and the sample was rinsed with deionized water to remove surface impurities. It was then dried at 60 °C for 10 h. Finally, the sample was heated in air at a rate of 3 °C / min. -1 The temperature was raised to 350℃ and calcined at 350℃ for 2 hours to obtain the cathode material, denoted as MnO2@CuO NWs / CF.

[0068] Comparative Example 2

[0069] Referring to Example 1, "Preparation of Anode Material", only Co(NO3)2·6H2O was replaced with equimolar amounts of Cd(NO3)2·4H2O, Cu(NO3)2·3H2O, Fe(NO3)3·9H2O, Mn(NO3)2·4H2O, Ni(NO3)2·6H2O, and Zn(NO3)2·6H2O. All other aspects were the same as in Example 1, "Preparation of Anode Material". The resulting materials were denoted as CdS2@CC, CuS2@CC, FeS2@CC, MnS2@CC, NiS2@CC, and ZnS2@CC, respectively.

[0070] Example 3

[0071] The inventors used a Chenhua 760 electrochemical workstation to test the electrochemical characteristics of different cathode materials (CuO NWs / CF, CeO2@CuONWs / CF, MnO2@CuO NWs / CF, CeO2-MnO2@CuO NWs / CF) and different anode materials (CoS2@CC, CdS2@CC, CuS2@CC, FeS2@CC, MnS2@CC, NiS2@CC, ZnS2@CC) and different anode materials. Figures 4-5The current-voltage and impedance curves show that CeO2-MnO2@CuO NWs / CF and CoS2@CC have larger current areas and smaller curve radii, indicating faster electron transfer during degradation, which is beneficial for improving the degradation rate of organic pollutants. Therefore, CeO2-MnO2@CuO NWs / CF was selected as the cathode material for the H-electrolyte, and CoS2@CC as the anode material.

[0072] The valence state and conduction band of CeO2-MnO2@CuO NWs / CF were tested using an electrochemical workstation to obtain an electron transfer mechanism diagram. Figure 6 Electrons transfer from CuO to CeO2-MnO2, while photogenerated electrons transfer from CeO2-MnO2 to CuO. Applying an external voltage in the same direction creates an internal electric field, suppressing carrier transfer between the two semiconductors. The internal electric field of CeO2-MnO2@CuO NWs / CF is opposite to the external voltage, thus improving interfacial conductivity. With the formation of a space charge layer, due to charge depletion, strongly positively charged active sites appear on the CeO2-MnO2 side of the heterojunction, leading to ROS generation and promoting HMX degradation.

[0073] Example 4

[0074] Based on the results of Example 3, CeO2-MnO2@CuO NWs / CF was selected as the cathode and CoS2@CC as the anode to investigate the electrocatalytic degradation of organic pollutants. The degradation effects of applying different current densities on HMX and DNAN were also investigated.

[0075] Investigation into the catalytic degradation of organic pollutants:

[0076] Weigh 10 mg of HMX into a 1 L volumetric flask and titrate to the mark with deionized water to obtain a 10 mg / L HMX solution. Weigh 15 mg of DNAN into a 1 L volumetric flask and titrate to the mark with deionized water to obtain a 15 mg / L DNAN solution. Adjust the initial pH of both the HMX and DNAN solutions to 7 using 0.1 mmol / L sulfuric acid and 0.1 mmol / L sodium hydroxide. Use anode material (CoS2@CC) as the anode in the anode chamber of the H-type electrolytic cell (anode area 1 cm²). 2 In the cathode chamber, the cathode material (CeO2-MnO2@CuO NWs / CF) is used as the cathode (cathode area 1 cm²). 2The two electrode chambers are separated by an N117 proton exchange membrane. 50 mL of HMX solution is placed in the cathode chamber of the H-type electrolytic cell, and 50 mL of DNAN solution is placed in the anode chamber. Simultaneously, persulfate (2KHSO5·KHSO4·K2SO4, final concentration 20 mg / L) is added to the anode chamber as an auxiliary activator for the anode material. The electrolyte in both the cathode and anode chambers is 0.05 mol / L Na2SO4. After energizing, approximately 2 mL of solution is taken from the cathode chamber every 10 min using a syringe, filtered through a 0.22 μm polyethersulfone membrane, and the remaining free radicals are quenched with 0.5 mL of methanol. Similarly, approximately 2 mL of solution is taken from the cathode chamber every 1 min using a syringe, filtered through a 0.22 μm polyethersulfone membrane, and the remaining free radicals are quenched with 0.5 mL of methanol. The concentration of HMX was detected at 254 nm and the concentration of DNAN was detected at 280 nm using a high-performance liquid chromatography (HPLC) instrument with a UV-Vis detector. A reversed-phase C18 column (5 μm, 4.6 mm × 250 mm) was used, with water and methanol (30%:70%) as the mobile phase at a flow rate of 1 mL / min. The peak areas of the solutions before and after degradation were measured by HPLC, and the ratio between the two was calculated to determine the degradation rate.

[0077] from Figure 7 It can be seen that without an applied current, the degradation of HMX and DNAN is almost 0%. When the current density increases from 5 mA·cm⁻¹... -2 Increased to 10 mA·cm -2 At 80 minutes of reaction, the total degradation rate of HMX increased from 63.2% to 95.1%. This improvement is attributed to the increased generation of reactive oxygen species with increasing current density. However, further increases in current led to a decrease in degradation efficiency. It is speculated that at higher currents, excess H2O2 may capture ·OH to generate O2H, which has a weaker oxidation potential and is less effective in removing organic pollutants. For the anode, without external current, the degradation rate of DNAN was 83.2% after 5 minutes of treatment, attributed to the activation of CoS2 by PMS (…). Figure 7 ); at a current density of 10 mA·cm -2 With further activation aided by an applied current, the removal rate of DNAN increased to 100%. Considering the degradation effects of HEF and AO, the optimal applied current density was 10 mA·cm⁻¹. -2 .

[0078] Example 5

[0079] The initial pH values ​​of the HMX solution and the DNAN solution were screened.

[0080] The initial pH of a 10 mg / L HMX solution was adjusted to 3, 5, 7, 9, and 11 using 0.1 mmol / L sulfuric acid and 0.1 mmol / L sodium hydroxide; the initial pH of a 15 mg / L DNAN solution was also adjusted to 3, 5, 7, 9, and 11 using 0.1 mmol / L sulfuric acid and 0.1 mmol / L sodium hydroxide.

[0081] Referring to Example 4, "Investigation of Electrocatalytic Degradation of Organic Pollutants," the degradation effect of initial pH on 10 mg / L HMX solution and 15 mg / L DNAN solution was investigated. Only the initial pH of the HMX solution added to the cathode chamber of the H-type electrolyzer and the initial pH of the DNAN solution added to the anode chamber of the H-type electrolyzer were adjusted. The initial pH of the HMX solution added to the cathode chamber and the DNAN solution added to the anode chamber of the H-type electrolyzer were the same. The applied current density was 10 mA·cm⁻¹. -2 The rest are the same as in Example 4, "Investigation of Electrocatalytic Degradation of Organic Pollutants".

[0082] from Figure 8 As can be seen, the removal rate of HMX (after 80 minutes of reaction) increases significantly as the pH value changes from weakly acidic to neutral. Specifically, at pH 3, the removal efficiency is inhibited due to the corrosion of the electrode under strong acid conditions. Under alkaline conditions, the consumption of H2O2 increases, further reducing the catalytic efficiency of the electrode.

[0083] from Figure 8 As shown in b, at an initial pH of 7-11, the degradation efficiency of DNAN (reaction time 5 minutes) exceeds 90% within 5 minutes. Under acidic conditions, abundant H+... + Will with SO4 ·- A reaction occurs, or through interaction with HSO5 - Hydrogen bonds are formed, which is detrimental to ROS formation. On the other hand, under strongly alkaline conditions, PMS mainly exists as SO5. 2- CoS2@CC and SO5 exist in the form of 2- The mutual electrostatic repulsion between them will lead to a decrease in the removal rate of DNAN.

[0084] When the initial pH of the cathode chamber is 5 and the initial pH of the anode chamber is 9, the H+ in the anode chamber... + Ion balance can be maintained through the N117 proton exchange membrane to the cathode chamber, thereby achieving maximum efficiency in dual degradation.

[0085] Example 6

[0086] Screening of electrolytes (and the effect of anions in solution on degradation). Referring to Example 4, "Investigation of Electrocatalytic Degradation of Organic Pollutants," the effects of different anions (SO42-) were investigated. 2- HCO3 -,Cl - NO3 - HPO4 - The degradation effects of HMX solution (10 mg / L, reacted for 80 minutes) and DNAN solution (15 mg / L, reacted for 5 minutes) provided by Na2SO4, NaHCO3, NaCl, NaNO3, and Na2HPO4, respectively, were observed. The only adjustments were made to: the initial pH of the HMX solution added to the cathode chamber of the H-type electrolytic cell was 5, and the initial pH of the DNAN solution added to the anode chamber was 9. The same anion was used as the electrolyte in both the cathode and anode chambers (concentration of 0.05 mol / L), and the applied current density was 10 mA·cm⁻¹. -2 .

[0087] from Figure 8 c shows that SO4 2- The impact on the degradation of organic pollutants is negligible, and the removal efficiency of DNAN and HMX is almost unaffected. - and HPO4 2- The effect on degradation is relatively small; the slight inhibitory effect is due to their interaction with ·OH and SO4. ·- The reaction forms HCO3·, Cl·, and HPO4·, which may hinder degradation. It is worth noting that when sodium bicarbonate is used as the electrolyte, it reacts with H+. + A reaction occurs that reduces the conductivity of the solution, leading to a decrease in current density, thereby reducing the degradation rate of DNAN and HMX. NO3 - It has no effect on DNAN degradation, but shows a small effect on HMX degradation, because NO3... - At the cathode, reduction occurs, generating additional OH-. - It consumes reactive oxygen species in the solution and causes competition with HMX degradation.

[0088] Example 7

[0089] Referring to Example 4, "Investigation of Electrocatalytic Degradation of Organic Pollutants," degradation was performed using a 10 mg / L HMX solution and a 15 mg / L DNAN solution, with the following adjustments made: the initial pH of the HMX solution added to the cathode chamber of the H-type electrolytic cell was 5, the initial pH of the DNAN solution added to the anode chamber of the H-type electrolytic cell was 9, the electrolyte was 0.05 mol / L Na₂SO₄, and the applied current density was 10 mA·cm⁻¹. -2 Electron paramagnetic resonance (EPR) was used to test the types of reactive oxygen species generated at the cathode and anode during the degradation process. Figure 9 The result is as follows Figures 10-11 As shown.

[0090] To investigate the reactive oxygen species generated during cathode degradation, 5,5-dimethyl-1-pyrrolline-N-oxide (DMPO) was used as a scavenger. The characteristic peak of DMPO-H* and the weak 1:2:2:1 response of DMPO-·OH were recorded. Figure 10 a) confirmed the formation of atoms H* and ·OH. Simultaneously, DMPO-O2· - The adduct signal was not captured, possibly because it readily converts to its derivative in alkaline solutions. 1 O2( Figure 10 c). Figure 10 b recorded the free radical signals at different time points, indicating that free radicals are continuously generated throughout the degradation process.

[0091] Investigate the reactive oxygen species generated during anodic degradation, such as Figure 11 As shown in a, all relevant reactive oxygen species (·OH, O2·) - and SO4 ·- Both can be captured in EPR. Figure 11 Tetramethylpiperidine oxide (TEMP) can be observed in b, and TEMP- is recorded. 1 The strong signal peak of the O2 adduct indicates that AO is produced during the reaction. 1 O2.

[0092] Example 8

[0093] Electron-deficient organic pollutants cyclotrimethylenetrinitramine (RDX, 20 mg / L) and hexanitrohexaazaisowrtzane (CL-20, 6 mg / L) were prepared using deionized water. The initial pH of both solutions was adjusted to 5 using 0.1 mmol / L sulfuric acid and 0.1 mmol / L sodium hydroxide. When the anode contaminant was an aqueous solution of DNAN (15 mg / L), either the RDX or hexanitrohexaazaisowrtzane solution was added as a single solution to the cathode chamber of the H-type electrolytic cell to form a combination. The cathode reaction time was 80 minutes, and the anode reaction time was 9 minutes.

[0094] Electron-rich organic pollutants trinitrotoluene (TNT), disodium azotetrazol (Na2AzTz), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine (NQ) were prepared using deionized water to prepare solutions of trinitrotoluene (TNT, 15 mg / L), disodium azotetrazol (Na2AzTz, 20 mg / L), 3-nitro-1,2,4-triazol-5-one (NTO, 30 mg / L), and nitroguanidine (NQ, 60 mg / L). The initial pH of the trinitrotoluene, disodium azotetrazol, 3-nitro-1,2,4-triazol-5-one, and nitroguanidine solutions was adjusted to 9 using 0.1 mmol / L sulfuric acid and 0.1 mmol / L sodium hydroxide. When the cathode chamber contaminant is an HMX solution (concentration of 10 mg / L), trinitrotoluene solution, azotetrazol disodium solution, 3-nitro-1,2,4-triazol-5-one solution, or nitroguanidine solution are added as single solutions to the anode chamber of the H-type electrolytic cell to form a combination. The cathode reaction time is 80 minutes and the anode reaction time is 9 minutes.

[0095] Referring to Example 4, "Investigation of Electrocatalytic Degradation of Organic Pollutants", only the pollutants in the cathode or anode chamber were adjusted. The anode material (CoS2@CC) was used as the anode, and the cathode material (CeO2-MnO2@CuO NWs / CF) was used as the cathode (both cathode and anode areas were 1 cm²). 2 The initial pH of the cathode chamber was 5, and the initial pH of the anode chamber was 9. The electrolyte in both the cathode and anode chambers was 0.05 mol / L SO4. 2- Current density 10 mA·cm -2 The degradation effect on different organic pollutants.

[0096] Experimental results are as follows Figure 12 As shown, within 2 hours, the degradation rates of cyclotrimethylenetrinitramine and hexanitrohexaazaisowrtzane reached 95.3% and 81.1%, respectively, with total organic carbon (TOC) removal rates of 66.7% and 41.1%, respectively. Within 9 minutes, the TOC removal rates of trinitrotoluene, disodium azotetrazole, 3-nitro-1,2,4-triazol-5-one, and nitroguanidine were 68%, 81%, 56%, and 73%, respectively, indicating that the cathode and anode materials of this invention have good applicability for treating typical explosive-deficient / explosive-rich wastewater.

[0097] Example 9

[0098] Referring to Example 4, "Investigation of Electrocatalytic Degradation of Organic Pollutants," the ability of the cathode and anode materials to degrade cyclically catalytically in HMX solution (10 mg / L) and DNAN solution (15 mg / L) was tested. Cathode degradation lasted 80 minutes, and anode degradation lasted 9 minutes. After degradation, the electrode materials were removed, rinsed with deionized water, and dried in an oven at 80°C for 3 hours. The catalyst was recovered, and the degradation of HMX solution (10 mg / L) and DNAN solution (15 mg / L) continued. The electrode materials recovered in the fifth cycle showed degradation rates of 90.2% and 92.5% for HMX solution (10 mg / L) and DNAN solution (15 mg / L), respectively. This indicates that the CeO2-MnO2@CuONWs / CF and CoS2@CC of this invention have excellent cyclicity and stability. The stability ensures high degradation rates while preventing sludge shedding.

Claims

1. A method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater, characterized in that: include: Using an H-type electrolytic cell, the cathode and anode chambers are separated by a proton exchange membrane. An aqueous solution of electron-deficient organic pollutants is added to the cathode chamber, while an aqueous solution of electron-rich organic pollutants and persulfate is added to the anode chamber. The cathode and anode materials are used as the cathode and anode, respectively, with SO42- as the reactant. 2- HCO3 - Cl - NO3 - or HPO4 2- It acts as an electrolyte, simultaneously degrading both electron-deficient and electron-rich organic pollutants under the action of an applied current; The cathode material is obtained by immersing copper foam in a mixed aqueous solution of NaOH and ammonium persulfate to obtain copper foam with Cu(OH)2 nanoneedle arrays. The copper foam with Cu(OH)2 nanoneedle arrays is then immersed in an aqueous solution of Mn(NO3)2·4H2O for reaction. Ce(NO3)2·6H2O is then added to continue the reaction. The mixture is then transferred to an aqueous solution of NaOH for treatment and dried to obtain a cathode material precursor. The cathode material precursor is then calcined in an air atmosphere to obtain the cathode material CeO2-MnO2@CuO NWs / CF. The molar ratio of Mn(NO3)2·4H2O to Ce(NO3)2·6H2O is 1:3 to 3:

3. The anode material is prepared by adding Co(NO3)2·6H2O and polyvinylpyrrolidone to a mixed solvent of water and ethylene glycol, then adding sodium thiosulfate to react and obtain a precursor solution. Activated carbon fiber cloth is then immersed in the precursor solution and heat-treated at 140–160 °C for 10–12 hours. After cooling to room temperature, the activated carbon fiber cloth is removed, washed with deionized water, and dried to obtain the anode material CoS2@CC. The concentration of the aqueous solution of the electron-deficient organic pollutant is 6–20 mg / L, and the concentration of the aqueous solution of the electron-rich organic pollutant is 10–60 mg / L. The electron-deficient organic pollutant is at least one of tetramethylenetetranitroamine, cyclotrimethylenetrinitramine, and hexanitrohexaazaisowulzane; the electron-rich organic pollutant is at least one of trinitrotoluene, disodium azotetrazole, 3-nitro-1,2,4-triazol-5-one, and nitroguanidine.

2. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 1, characterized in that: The area of ​​the cathode is 1 cm². 2 The area of ​​the anode is 1 cm². 2 The applied current density is 5–20 mA.

3. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 2, characterized in that: The area of ​​the cathode is 1 cm². 2 The area of ​​the anode is 1 cm². 2 The applied current density is 10–15 mA.

4. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 3, characterized in that: The area of ​​the cathode is 1 cm². 2 The area of ​​the anode is 1 cm². 2 The applied current density is 10 mA.

5. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 1, characterized in that: The initial pH of the aqueous solution of electron-deficient organic pollutants in the cathode chamber is 3-11; the initial pH of the aqueous solution of electron-rich organic pollutants in the anode chamber is 3-11. The final concentration of the persulfate is 20–25 mg / L; the concentration of the electrolyte is 0.050–0.055 mol / L. The electrolyte is SO4. 2- Or NO3 - .

6. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 5, characterized in that: The initial pH of the aqueous solution of electron-deficient organic pollutants in the cathode chamber is 5-7; the initial pH of the aqueous solution of electron-rich organic pollutants in the anode chamber is 7-11.

7. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 6, characterized in that: The initial pH of the aqueous solution of electron-deficient organic pollutants in the cathode chamber is 5; the initial pH of the aqueous solution of electron-rich organic pollutants in the anode chamber is 9.

8. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 5, characterized in that: The electrolyte is SO4. 2- .

9. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 1, characterized in that: The cathode material is prepared by the following method: At room temperature, activated copper foam is immersed in a mixed aqueous solution of NaOH and ammonium persulfate for 0.5–1 h to obtain copper foam with a Cu(OH)₂ nanoneedle array; the copper foam with the Cu(OH)₂ nanoneedle array is immersed in an aqueous solution of Mn(NO₃)₂·4H₂O and reacted at 70–85 °C for 0.8–1.2 h, followed by the addition of Ce(NO₃)₂·6H₂O and reacted at 70–85 °C for 0.8–1.2 h; the copper foam is then transferred to an aqueous solution of NaOH and soaked at room temperature for 30–40 minutes; the copper foam is then removed, rinsed with deionized water, and dried to obtain the cathode material precursor; the cathode material precursor is calcined in air at 300–350 °C for 2–2.5 h to obtain the cathode material.

10. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 1 or 9, characterized in that: In the mixed aqueous solution of NaOH and ammonium persulfate, the concentration of NaOH is 2-2.5 mol / L and the concentration of ammonium persulfate is 0.10-0.16 mol / L.

11. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 1 or 9, characterized in that: The concentration of the Mn(NO3)2·4H2O aqueous solution is 0.1–0.166 mol / L; the molar ratio of Mn(NO3)2·4H2O to Ce(NO3)2·6H2O is 2:

3.

12. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 1, characterized in that: The anode material is prepared by the following method: Co(NO3)2·6H2O and polyvinylpyrrolidone are added to a mixed solvent of ethylene glycol and mixed evenly. Sodium thiosulfate is added and reacted at room temperature for 1.5 to 2 hours. The mixture is then ultrasonically treated for 30 to 40 minutes to obtain a dispersion. Activated carbon fiber cloth is immersed in the dispersion and heat-treated at 140 to 160 °C for 12 hours. The activated carbon fiber cloth is then removed, washed with deionized water, and dried at 50 to 70 °C for 8 to 12 hours to obtain the anode material.

13. The method for simultaneously degrading typical explosive-deficient / explosive-rich wastewater according to claim 1 or 12, characterized in that: The mass ratio of Co(NO3)2·6H2O to polyvinylpyrrolidone is 0.95:1 to 1:1; the volume ratio of Co(NO3)2·6H2O to water is 1:30 to 1:35 g / mL; the volume ratio of water to ethylene glycol is 1:1; and the molar ratio of Co(NO3)2·6H2O to sodium thiosulfate is 0.5:1 to 0.55:1.

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