Iron-based double-monatomic catalyst, preparation method thereof and coupling copper film

Abstract

The invention belongs to the technical field of organic sewage treatment, and particularly discloses an iron-based double-monatomic catalyst, a preparation method thereof and a coupling copper film. The preparation method comprises the following steps: reacting a mixed solution containing iron phthalocyanine with an alcoholic solution of zinc nitrate to obtain ZnFe-ZIF; after the mixed solution is mixed with a NaCl solution, NaCl and ZnFe-ZIF crystals are separated out; and then calcining to obtain ZnFe-NC, mixing the ZnFe-NC with a second metal salt and alcohol, and sequentially calcining, pickling and drying the obtained solid to obtain the iron-based double-monatomic catalyst, and coating the iron-based double-monatomic catalyst dispersion liquid on the copper film to obtain the iron-based double-monatomic catalyst coupling copper film. The prepared catalyst and the coupling copper film can accelerate activation of PMS, improve the degradation rate and speed, have good stability and show a good degradation effect under the condition that different pH values, different concentrations of HA solutions and different anions coexist.

Description

Technical Field

[0001] The present invention relates to the technical field of organic sewage treatment, and particularly relates to an iron-based dual single-atom catalyst and a preparation method thereof, and a coupled copper film. Background Art

[0002] Among numerous pollutants, the accumulation of macromolecular organic matters such as dyes and small-molecular organic matters such as antibiotics and personal care products (PPCPs) has become a key factor affecting water quality. Sulfonamide antibiotics widely used in the livestock and poultry breeding industry, due to their complex molecular structure, characteristics of being difficult to biodegrade, high toxicity of secondary pollutants, and biological accumulation and amplification effects, the ecological and health safety problems caused in water bodies are becoming increasingly serious. Therefore, how to effectively degrade such pollutants is particularly important.

[0003] As a kind of AOPs, the persulfate activation method has attracted much attention in recent years due to its high efficiency, environmental protection and wide applicability. Among them, the transition metal activation method has the advantages of high efficiency and broad spectrum, strong oxidation ability of generated free radicals, low requirements for operating conditions, recyclability and stability of catalysts. However, the electronic structure and coordination environment of the metal center of the single-atom catalyst are easily restricted by the substrate, resulting in poor stability of the active sites. How to prepare a dual single-atom catalyst for efficient degradation of pollutants has become a major challenge in catalyst design and catalytic system construction, and has important scientific significance and application prospects. Summary of the Invention

[0004] In view of this, the present invention provides an iron-based dual single-atom catalyst and a preparation method thereof, and a coupled copper film, so as to solve the problem that the electronic structure and coordination environment of the metal center of the existing single-atom catalyst are easily restricted by the substrate, resulting in poor stability of the active sites.

[0005] In order to achieve the above purpose, the present invention adopts the following technical scheme:

[0006] A preparation method of an iron-based dual single-atom catalyst includes the following steps:

[0007] 1) Mix a mixed solution containing iron phthalocyanine with an alcohol solution of zinc nitrate for reaction to obtain ZnFe-ZIF;

[0008] 2) Mix ZnFe-ZIF with an NaCl solution to obtain a mixed solution, and use alcohol to precipitate NaCl@ZnFe-ZIF crystals from the mixed solution;

[0009] 3) Calcinate the NaCl@ZnFe-ZIF crystals to obtain ZnFe-NC;

[0010] 4) Mix ZnFe-NC, the second metal salt and alcohol, and after solid-liquid separation, calcine, pickling and drying the solid in sequence to obtain the iron-based dual single-atom catalyst.

[0011] Preferably, the preparation method of the iron phthalocyanine-containing mixed solution in step 1) is: mix iron phthalocyanine, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, dimethylimidazole and alcohol;

[0012] The dosage ratio of the iron phthalocyanine, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, dimethylimidazole and alcohol is 0.1-0.2 mmol: 0.3-0.4 g: 2-3 g: 40-50 mL;

[0013] The alcohol includes one or more of methanol, ethanol and n-butanol.

[0014] Preferably, the molar volume ratio of zinc nitrate to alcohol in the zinc nitrate alcohol solution in step 1) is 5-6 mmol: 40-50 mL;

[0015] The alcohol includes one or more of methanol, ethanol and n-butanol.

[0016] Preferably, the molar ratio of iron phthalocyanine in the iron phthalocyanine-containing mixed solution to zinc nitrate in the zinc nitrate alcohol solution in step 1) is 0.1-0.2: 5-6; the reaction time in step 1) is 4-12 h.

[0017] Preferably, the mass-to-volume ratio of ZnFe-ZIF to the NaCl solution in step 2) is 50-100 mg: 20-40 mL;

[0018] The mass concentration of the NaCl solution is ≥30%;

[0019] The calcination temperature in step 3) is 800-900 °C, and the calcination time is 2-3 h.

[0020] Preferably, the dosage ratio of ZnFe-NC, the second metal salt and alcohol in step 4) is 80 mg: 0.2-0.4 mmol: 40-50 mL;

[0021] The second metal salt includes one or more of iron salts, manganese salts, vanadium salts and nickel salts;

[0022] The alcohol includes one or more of methanol, ethanol and n-butanol.

[0023] Preferably, the calcination temperature in step 4) is 800-900 °C, and the calcination time is 2-3 h;

[0024] The acid solution used for pickling in step 4) includes hydrochloric acid and / or sulfuric acid;

[0025] The molar concentration of the acid solution is 1-5 mol / L;

[0026] The pickling time is 6-12 h.

[0027] Another object of the present invention is to provide an iron-based dual single-atom catalyst prepared by the above preparation method.

[0028] Another object of the present invention is to provide an application of the iron-based dual single-atom catalyst in organic sewage treatment.

[0029] Another object of the present invention is to provide an iron-based dual single-atom catalyst coupled with a copper film, comprising the following preparation steps: mixing the iron-based dual single-atom catalyst with a solvent to obtain a dispersion liquid, and coating the dispersion liquid on the copper film to obtain the iron-based dual single-atom catalyst coupled with the copper film;

[0030] The iron-based dual single-atom catalyst is the above-mentioned iron-based dual single-atom catalyst.

[0031] Through the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) Based on zinc-based MOF, the present invention adds iron salt and a second metal salt to obtain an iron-based dual single-atom catalyst. A synergistic effect occurs between the two metals in this catalyst, which is a highly active catalyst.

[0033] (2) The iron-based dual single-atom catalyst of the present invention can accelerate the activation of PMS, improve the degradation rate and rate.

[0034] (3) The iron-based dual single-atom catalyst of the present invention has good stability and shows good degradation effects under different pH values, different concentrations of humic acid solutions, and the coexistence of different anions.

[0035] (4) By combining the dual single-atom catalyst with the copper film, the present invention shows good degradation effects and stability. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0037] Figure 1 HAADF-HRTEM image of FeMn DACs in Example 1;

[0038] Figure 2 EDS mapping of FeMn DACs in Example 1;

[0039] Figure 3 Removal rate and degradation rate diagrams of four sulfonamide antibiotics by FeMn DACs in Example 1;

[0040] Figure 4 Removal effect diagram of pollutants by FeMn DACs in Example 1 after five cycles;

[0041] Figure 5 Removal effect diagram of pollutants by FeMn DACs in Example 1 under different environments;

[0042] Figure 6 HAADF-HRTEM diagram of FeFe DACs in Example 2;

[0043] Figure 7 EDS mapping of FeFe DACs in Example 2;

[0044] Figure 8 Removal rate and degradation rate diagrams of four sulfonamide antibiotics by FeFe DACs in Example 2;

[0045] Figure 9 Diagram of CuM and FeMn DACs-CuM in Example 3, where Figure 9 a in corresponds to CuM, Figure 9 b in corresponds to FeMn DACs-CuM;

[0046] Figure 10 Cross-section SEM diagram of FeMn DACs-CuM in Example 3;

[0047] Figure 11 EDS mapping of FeMn DACs-CuM in Example 3;

[0048] Figure 12 Comparison diagram of water contact angles between FeMn DACs-CuM and CuM in Example 3;

[0049] Figure 13 Stable performance diagram of long-term degradation of antibiotics by FeMn DACs-CuM in Example 3;

[0050] Figure 14 Removal rate and degradation rate diagrams of four sulfonamide antibiotics by FeNi DACs in Example 4;

[0051] Figure 15Removal rate and degradation rate diagrams of four sulfonamide antibiotics by FeV DACs of Example 5. Detailed implementation mode

[0052] The present invention provides a preparation method of an iron-based dual single-atom catalyst, comprising the following steps:

[0053] 1) Mix a mixed solution containing iron phthalocyanine with an alcoholic solution of zinc nitrate for reaction to obtain ZnFe-ZIF;

[0054] 2) Mix ZnFe-ZIF with an NaCl solution to obtain a mixed solution, and use alcohol to precipitate NaCl@ZnFe-ZIF crystals from the mixed solution;

[0055] 3) Calcinate the NaCl@ZnFe-ZIF crystals to obtain ZnFe-NC;

[0056] 4) Mix ZnFe-NC, a second metal salt and alcohol, and after solid-liquid separation, calcine, pickling and drying the solid in sequence to obtain the iron-based dual single-atom catalyst.

[0057] In the present invention, the preparation method of the mixed solution containing iron phthalocyanine in step 1) is: mix iron phthalocyanine, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, 2-methylimidazole and alcohol.

[0058] The dosage ratio of the iron phthalocyanine, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, 2-methylimidazole and alcohol is 0.1-0.2 mmol: 0.3-0.4 g: 2-3 g: 40-50 mL, preferably 0.1-0.15 mmol: 0.3-0.35 g: 2-2.5 g: 40-45 mL, and further preferably 0.1 mmol: 0.3 g: 2 g: 40 mL.

[0059] The alcohol includes one or more of methanol, ethanol and n-butanol.

[0060] In the present invention, the molar volume ratio of zinc nitrate to alcohol in the alcoholic solution of zinc nitrate in step 1) is 5-6 mmol: 40-50 mL, preferably 5.5-6 mmol: 40-45 mL, and further preferably 6 mmol: 40 mL.

[0061] In the present invention, the alcohol includes one or more of methanol, ethanol and n-butanol.

[0062] In the present invention, the molar mass ratio of iron phthalocyanine in the mixed solution containing iron phthalocyanine in step 1) to zinc nitrate in the alcoholic solution of zinc nitrate is 0.1-0.2:5-6, preferably 0.12-0.18:5.5-6, and more preferably 0.15:6; the reaction time in step 1) is 4-12 h, specifically it can be 5 h, 6 h, 8 h, 10 h.

[0063] In the present invention, the mass-to-volume ratio of ZnFe-ZIF to the NaCl solution in step 2) is 50-100 mg:20-40 mL, preferably 60-90 mg:25-35 mL, and more preferably 80 mg:30 mL.

[0064] In the present invention, the mass concentration of the NaCl solution is ≥30%, specifically it can be 32%, 34%, 35%, 36%, 38%, 40%; preferably it is a saturated NaCl solution.

[0065] In the present invention, the calcination temperature in step 3) is 800-900 °C, specifically it can be 820 °C, 840 °C, 850 °C, 860 °C, 880 °C; the calcination time is 2-3 h, specifically it can be 2.2 h, 2.4 h, 2.5 h, 2.6 h, 2.8 h.

[0066] In the present invention, the dosage ratio of ZnFe-NC, the second metal salt and the alcohol in step 4) is 80 mg:0.2-0.4 mmol:40-50 mL, preferably 80 mg:0.25-0.35 mmol:42-48 mL, and more preferably 80 mg:0.3 mmol:45 mL.

[0067] In the present invention, the second metal salt includes one or more of iron salts, manganese salts, vanadium salts and nickel salts; specifically, the iron salt can be iron phthalocyanine, the manganese salt can be manganese chloride, the nickel salt can be nickel phthalocyanine, and the vanadium salt can be vanadium chloride.

[0068] In the present invention, the alcohol includes one or more of methanol, ethanol and n-butanol.

[0069] In the present invention, the calcination temperature in step 4) is 800-900 °C, specifically it can be 820 °C, 840 °C, 850 °C, 860 °C, 880 °C; the calcination time is 2-3 h, specifically it can be 2.2 h, 2.4 h, 2.5 h, 2.6 h, 2.8 h.

[0070] In the present invention, the acid solution used for pickling in step 4) includes hydrochloric acid and / or sulfuric acid.

[0071] In the present invention, the molar concentration of the acid solution is 1 to 5 mol / L, specifically, it can be 2 mol / L, 3 mol / L, or 4 mol / L.

[0072] In the present invention, the pickling time is 6 to 12 h, specifically, it can be 7 h, 8 h, 9 h, 10 h, or 11 h.

[0073] The present invention also provides an iron-based dual single-atom catalyst prepared by the above preparation method.

[0074] The present invention also provides an application of the iron-based dual single-atom catalyst in organic sewage treatment.

[0075] The present invention also provides an iron-based dual single-atom catalyst coupled with a copper film, which includes the following preparation steps: mixing the iron-based dual single-atom catalyst with a solvent to obtain a dispersion liquid, and coating the dispersion liquid on the copper film to obtain the iron-based dual single-atom catalyst coupled with the copper film.

[0076] In the present invention, the solvent is preferably a mixture of water and naphthol, and the volume ratio of water to naphthol is preferably 0.95 to 0.99:0.01 to 0.05, more preferably 0.96 to 0.98:0.02 to 0.04, and further preferably 0.98:0.02.

[0077] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0078] Example 1

[0079] Weigh 0.3 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock polymer, 2 g of dimethylimidazole, and 56.8 mg (0.1 mmol) of iron phthalocyanine, dissolve them in 40 mL of methanol, ultrasonically disperse them until uniform, seal with a sealing film (to prevent methanol from volatilizing), stir for 30 min to obtain a mixed solution ①. Then, dissolve 6 mmol of zinc nitrate hexahydrate in 40 mL of methanol, ultrasonically disperse it until uniform, seal with a sealing film (to prevent methanol from volatilizing), stir for 30 min to obtain a mixed solution ②. Subsequently, add solution ② to mixed solution ① to obtain solution ③, seal with a sealing film, and stir at room temperature for 6 h. After stirring is completed, centrifuge with a methanol solution at a speed of 6000 r / min for 3 times, with each centrifugation time being 3 min. Finally, pour the supernatant into the waste liquid tank to obtain the bottom precipitate.

[0080] Wrap the top of the centrifuge tube containing the precipitated substance with tin foil to prevent interference from other substances. Place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain ZnFe-ZIF. Dissolve the obtained ZnFe-ZIF in saturated NaCl solution (the mass-volume ratio of ZnFe-ZIF to NaCl solution is 80 mg: 30 mL), sonicate until homogeneous, stir, and continuously add ethanol until NaCl recrystallizes. Cover the top of the beaker with tin foil to prevent interference from other substances, place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain NaCl@ZnFe-ZIF. Take out the dried NaCl@ZnFe-ZIF, transfer it to a mortar and grind it into fine powder. After grinding, transfer it to a ceramic boat, place it in a tubular furnace, and under a nitrogen atmosphere, heat it at a rate of 5 °C per minute to 900 °C and sinter for 2 h to obtain ZnFe-NC. Add 80 mg of ZnFe-NC and 79.2 mg (0.4 mmol) of manganese chloride tetrahydrate to 40 mL of methanol, sonicate until homogeneous, stir for 5 h, then centrifuge 4 times at a speed of 6000 r / min, collect the precipitate, then dry it at 60 °C, grind it after drying, transfer it to a ceramic boat, place it in a tubular furnace, and under a nitrogen atmosphere, heat it at a rate of 5 °C per minute to 900 °C and sinter for 2 h to obtain FeMn DACs. After sintering, wait for it to cool to room temperature and then take it out. Then immerse the obtained catalyst in 1 mol / L dilute HCl solution for acid washing for 10 h to remove impurities. Centrifuge to collect the final black product FeMn DACs, centrifuge 3 times with deionized water at a speed of 6000 r / min, collect the precipitate, and then dry it at 60 °C to obtain an iron-based dual single-atom catalyst, denoted as FeMn DACs.

[0081] The HAADF-HRTEM image of FeMn DACs prepared in this example is as Figure 1 shown, and the EDS maps are as Figure 2 shown. It can be seen from Figure 1 and 2 that the Fe element, Mn element, C element, and N element are evenly dispersed, exposing more reactive sites, which is helpful for the efficient degradation of sulfonamide antibiotics.

[0082] Conduct a pollutant degradation experiment on FeMn DACs of this example. Mix 5 mg of the synthesized FeMn DACs with four sulfonamide antibiotic solutions at 10 mg / L (SDZ - sulfadiazine, SM2 - sulfamethazine, SMD - sulfamethoxypyridazine, SMM - sulfamonomethoxine) in sequence, and add 0.1 mM PMS as an oxidant respectively. The results are as Figure 3 shown. It can be seen from Figure 3It can be seen that the removal rates of the four sulfonamide antibiotics by FeMn DACs within 5 minutes are all above 90%, and the k value (rate constant) reaches 1.2 min -1 .

[0083] After the above reaction is completed, transfer the solution to a centrifuge tube, centrifuge it, and wash it with deionized water multiple times to remove residual pollutants. Dry and recover the catalyst. Put the recovered catalyst into a new sulfonamide antibiotic solution (SDZ - sulfadiazine), repeat the above degradation experiment 5 times, and record the degradation efficiency of the catalyst after each experiment. The results are as Figure 4 shown, indicating that FeMn DACs have good stability.

[0084] Carry out the above degradation experiments in solutions with different humic acid (HA) concentrations (5 mg / L, 10 mg / L, 15 mg / L respectively) and in solutions coexisting with different anions (15 mg / L chloride ion, 15 mg / L bicarbonate ion, 15 mg / L nitrate ion respectively). The results are as Figure 5 shown, and the degradation rates are all above 90%, indicating that FeMn DACs also have good stability under complex water environment conditions.

[0085] Example 2

[0086] Weigh 0.3 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock polymer, 2 g of dimethylimidazole, and 56.8 mg (0.1 mmol) of iron phthalocyanine, dissolve them in 40 mL of methanol, ultrasonically disperse until uniform, seal with a sealing film (to prevent methanol volatilization), stir for 30 min to obtain mixed solution ①. Then dissolve 6 mmol of zinc nitrate hexahydrate in 40 mL of methanol, ultrasonically disperse until uniform, seal with a sealing film (to prevent methanol volatilization), stir for 30 min to obtain mixed solution ②. Subsequently, add solution ② to mixed solution ① to obtain solution ③, seal with a sealing film, and stir at room temperature for 6 h. After stirring is completed, centrifuge with a methanol solution at a speed of 6000 r / min for 3 times, each time for 3 min. Finally, pour the supernatant into the waste liquid tank to obtain the bottom precipitate.

[0087] Wrap the top of the centrifuge tube containing the precipitated substance with tin foil to prevent interference from other substances. Place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain ZnFe-ZIF. Dissolve the obtained ZnFe-ZIF in a saturated NaCl solution (the mass-volume ratio of ZnFe-ZIF to the NaCl solution is 100 mg: 30 mL), sonicate until homogeneous, stir, and continuously add ethanol until NaCl recrystallizes. Cover the top of the beaker with tin foil to prevent interference from other substances, place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain NaCl@ZnFe-ZIF. Take out the dried NaCl@ZnFe-ZIF, transfer it to a mortar and grind it into fine powder. After grinding, transfer it to a ceramic boat, place it in a tube furnace, and under a nitrogen atmosphere, heat it at a rate of 5 °C per minute and sinter it at 900 °C for 2 h to obtain ZnFe-NC. Add 80 mg of ZnFe-NC and 56.8 mg (0.1 mmol) of iron phthalocyanine to 40 mL of methanol, sonicate until homogeneous, stir for 5 h, then centrifuge 4 times at a speed of 6000 r / min, collect the precipitate, then dry it at 60 °C, and after grinding it, transfer it to a ceramic boat, place it in a tube furnace, and under a nitrogen atmosphere, heat it at a rate of 5 °C per minute and sinter it at 900 °C for 2 h to obtain FeFe DACs. After sintering, wait for it to cool to room temperature and then take it out. Then immerse the obtained catalyst in a 1 mol / L dilute HCl solution for pickling for 10 h to remove impurities. Centrifuge to collect the final black product FeFe DACs, centrifuge 3 times with deionized water at a speed of 6000 r / min, collect the precipitate, and then dry it at 60 °C to obtain an iron-based dual single-atom catalyst, denoted as FeFe DACs.

[0088] The HAADF-HRTEM images of the FeFe DACs prepared in this example are as Figure 6 shown, and the EDS maps are as Figure 7 shown. It can be seen from Figure 6 and Figure 7 that the Fe, C, N, and O elements are evenly dispersed, exposing more reactive sites, which is helpful for the efficient degradation of sulfonamide antibiotics.

[0089] Conduct a pollutant degradation experiment on the FeFe DACs of this example. Mix 5 mg of the synthesized FeFe DACs with four sulfonamide antibiotic solutions at 10 mg / L (SDZ - sulfadiazine, SM2 - sulfamethazine, SMD - sulfamethoxypyridazine, SMM - sulfamonomethoxine) in sequence, and add 0.1 mM PMS as an oxidant respectively. The results are as Figure 8 shown. It can be seen from Figure 8 that the removal rate of FeFe DACs for these four sulfonamide antibiotics is around 90% or above within 5 min.

[0090] Example 3

[0091] Weigh 0.3 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock polymer, 2 g of dimethylimidazole, and 56.8 mg (0.1 mmol) of iron phthalocyanine, dissolve them in 40 mL of methanol, ultrasonicate until evenly dispersed, seal with a sealing film (to prevent methanol volatilization), stir for 30 min to obtain mixed solution ①. Then, dissolve 6 mmol of zinc nitrate hexahydrate in 40 mL of methanol, ultrasonicate until evenly dispersed, seal with a sealing film (to prevent methanol volatilization), stir for 30 min to obtain mixed solution ②. Subsequently, add solution ② to mixed solution ① to obtain solution ③, seal with a sealing film, and stir at room temperature for 6 h. After stirring is completed, centrifuge with a methanol solution at a speed of 6000 r / min for 3 times, with each centrifugation time being 3 min. Finally, pour the supernatant into the waste liquid tank to obtain the bottom precipitate.

[0092] Wrap the top of the centrifuge tube containing the precipitate with tin foil to prevent interference from other substances, place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain ZnFe-ZIF. Dissolve the obtained ZnFe-ZIF in a saturated NaCl solution (the mass-volume ratio of ZnFe-ZIF to the NaCl solution is 80 mg:30 mL), ultrasonicate until uniform, stir, and continuously add ethanol until NaCl recrystallizes. Cover the top of the beaker with tin foil to prevent interference from other substances, place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain NaCl@ZnFe-ZIF. Take out the dried NaCl@ZnFe-ZIF, transfer it to a mortar and grind it into fine powder. After grinding, transfer it to a ceramic boat, place it in a tube furnace, and under a nitrogen atmosphere, heat it at a heating rate of 5 °C to 900 °C for 2 h to obtain ZnFe-NC. Add 80 mg of ZnFe-NC and 79.2 mg (0.4 mmol) of manganese chloride tetrahydrate to 40 mL of methanol, ultrasonicate until uniform, stir for 5 h, then centrifuge at a speed of 6000 r / min for 4 times, collect the precipitate, then dry it at 60 °C, grind it, transfer it to a ceramic boat, place it in a tube furnace, and under a nitrogen atmosphere, heat it at a heating rate of 5 °C to 900 °C for 2 h to obtain FeMn DACs. After firing is completed, wait for it to cool to room temperature and then take it out. Then immerse the obtained catalyst in a 1 mol / L dilute HCl solution for pickling for 10 h to remove impurities. Centrifuge to collect the final black product FeMn DACs, centrifuge with deionized water at a speed of 6000 r / min for 3 times, collect the precipitate, and then dry it at 60 °C to obtain an iron-based dual single-atom catalyst, denoted as FeMn DACs.

[0093] Weigh 3 g of copper powder and press it with a pressing machine at a pressure of 20 MPa for 5 min to obtain a well-pressed copper film. Transfer the copper film to a quartz boat, place it in a tube furnace under a nitrogen atmosphere, heat it at 500 °C for 1 h, and the heating and cooling rates are both 2 °C / min to obtain the treated copper film (as shown in a of Figure 9 ), denoted as CuM.

[0094] The above-prepared FeMn DACs are configured into a FeMn DACs dispersion (5 mg of FeMn DACs are dissolved in 0.98 mL of ultrapure water and 0.02 mL of naphthol) and uniformly coated on the treated copper film, and air-dried to obtain an iron-based dual single-atom catalyst-coupled copper film, denoted as FeMn DACs-CuM.

[0095] The iron-based dual single-atom catalyst-coupled copper film prepared in this example is as shown in Figure 9 b of Figure 9 . It can be seen that the dual single-atom catalyst is uniformly dispersed on the copper film, which is helpful for the efficient degradation of sulfonamide antibiotics.

[0096] The cross-section of the dual single-atom modified copper film prepared in this example was observed by scanning electron microscopy, as shown in Figure 10 . It can be seen from Figure 10 that FeMn DACs are uniformly distributed on the entire copper film substrate.

[0097] The EDS mapping of FeMn DACs-CuM is as shown in Figure 11 . It can be seen through Figure 11 that the distribution of each element is uniform, which is helpful for the efficient degradation of sulfonamide antibiotics.

[0098] The comparison of the water contact angles between the dual single-atom modified copper film and the pure copper film prepared in this example is as shown in Figure 12 . It can be seen from Figure 12 that the modified copper film has better water permeability.

[0099] The dual single-atom modified copper film prepared in this example was subjected to a long-term degradation experiment. In a 5 L solution containing 1 mg / L of SDZ pollutant, the PMS concentration was 0.25 mM. After installing the membrane device, cross-flow filtration was used, and the SDZ degradation experiment was carried out under the application of a voltage of 0.1 v. The removal rate of SDZ is as shown in Figure 13 . The results show that in the long-term operation of 2500 min of the catalytic system of the FeMn DACs-modified copper film, the removal rate has been maintained above 97%, indicating that the FeMn DACs-modified copper film prepared by the present invention has high activity and stability and has the potential for practical application.

[0100] Example 4

[0101] Weigh 0.4 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock polymer, 2.5 g of dimethylimidazole, and 0.2 mmol of iron phthalocyanine, dissolve them in 50 mL of ethanol, sonicate until evenly dispersed, seal with a sealing film (to prevent ethanol volatilization), stir for 30 min to obtain mixed solution ①. Then, dissolve 6 mmol of zinc nitrate hexahydrate in 40 mL of ethanol, sonicate until evenly dispersed, seal with a sealing film (to prevent ethanol volatilization), stir for 30 min to obtain mixed solution ②. Subsequently, add solution ② to mixed solution ① to obtain solution ③, seal with a sealing film, and stir at room temperature for 8 h. After stirring, centrifuge with an ethanol solution at a speed of 6000 r / min for 3 times, with each centrifugation time being 3 min. Finally, pour the supernatant into the waste liquid tank to obtain the bottom precipitate.

[0102] Wrap the top of the centrifuge tube containing the precipitate with tin foil to prevent interference from other substances, place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain ZnFe-ZIF. Dissolve the obtained ZnFe-ZIF in saturated NaCl solution (the mass-volume ratio of ZnFe-ZIF to NaCl solution is 80 mg:40 mL), sonicate until uniform, stir, and continuously add ethanol until NaCl recrystallizes. Cover the top of the beaker with tin foil to prevent interference from other substances, place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain NaCl@ZnFe-ZIF. Take out the dried NaCl@ZnFe-ZIF, transfer it to a mortar and grind it into fine powder. After grinding, transfer it to a ceramic boat, place it in a tubular furnace, and under a nitrogen atmosphere, heat it at a heating rate of 5 °C to 800 °C for 2 h to obtain ZnFe-NC. Add 80 mg of ZnFe-NC and 114 mg (0.2 mmol) of nickel phthalocyanine to 40 mL of methanol, sonicate until uniform, stir for 5 h, then centrifuge at a speed of 6000 r / min for 4 times, collect the precipitate, then dry it at 60 °C, grind it, transfer it to a ceramic boat, place it in a tubular furnace, and under a nitrogen atmosphere, heat it at a heating rate of 5 °C to 800 °C for 2 h to obtain FeNi DACs. After firing, wait for it to cool to room temperature and then take it out. Then immerse the obtained catalyst in 2 mol / L dilute HCl solution for pickling for 11 h to remove impurities. Centrifuge to collect the final black product FeNi DACs, centrifuge with deionized water at a speed of 6000 r / min for 3 times, collect the precipitate, and then dry it at 60 °C to obtain the iron-based dual single-atom catalyst, denoted as FeNi DACs.

[0103] The pollutant degradation experiment of the FeNi DACs in this example was carried out. 5 mg of the synthesized FeNi DACs were respectively mixed with four sulfonamide antibiotic solutions at a concentration of 10 mg / L (SDZ - sulfadiazine, SM2 - sulfamethazine, SMD - sulfamethoxydiazine, SMM - sulfamonomethoxine) in sequence, and 0.1 mM PMS was added as the oxidant respectively. The results are as Figure 14 shown. It can be seen from Figure 14 that the removal rates of the four sulfonamide antibiotics by FeNi DACs within 5 min are all above 90%.

[0104] Example 5

[0105] Weigh 0.35 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock polymer, 3 g of dimethylimidazole, and 0.2 mmol of iron phthalocyanine, dissolve them in 40 mL of methanol, ultrasonicate until evenly dispersed, seal with a sealing film (to prevent methanol volatilization), stir for 30 min to obtain mixed solution ①. Then take 6 mmol of zinc nitrate hexahydrate and dissolve it in 40 mL of methanol, ultrasonicate until evenly dispersed, seal with a sealing film (to prevent methanol volatilization), stir for 30 min to obtain mixed solution ②. Subsequently, add solution ② to mixed solution ① to obtain solution ③, seal with a sealing film, and stir at room temperature for 10 h. After stirring is completed, centrifuge with a methanol solution at a speed of 6000 r / min for 3 times, with each centrifugation time being 3 min. Finally, pour the supernatant into the waste liquid tank to obtain the bottom precipitate.

[0106] Wrap the top of the centrifuge tube containing the precipitated substance with tin foil to prevent interference from other substances. Place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain ZnFe-ZIF. Dissolve the obtained ZnFe-ZIF in saturated NaCl solution (the mass-volume ratio of ZnFe-ZIF to NaCl solution is 80 mg: 20 mL), sonicate until uniform, stir, and continuously add ethanol until NaCl recrystallizes. Cover the top of the beaker with tin foil to prevent interference from other substances, place it in an oven, set the temperature to 60 °C, and wait for it to dry to obtain NaCl@ZnFe-ZIF. Take out the dried NaCl@ZnFe-ZIF, transfer it to a mortar and grind it into fine powder. After grinding, transfer it to a ceramic boat, place it in a tube furnace, and under a nitrogen atmosphere, heat it at a rate of 5 °C per minute and calcine it at 850 °C for 2 h to obtain ZnFe-NC. Add 80 mg of ZnFe-NC and 47 mg (0.3 mmol) of vanadium chloride to 45 mL of methanol, sonicate until uniform, stir for 5 h, then centrifuge 4 times at a speed of 6000 r / min, collect the precipitate, then dry it at 60 °C, and after grinding it, transfer it to a ceramic boat, place it in a tube furnace, and under a nitrogen atmosphere, heat it at a rate of 5 °C per minute and calcine it at 800 °C for 2 h to obtain FeV DACs. After the calcination is completed, wait for it to cool to room temperature and then take it out. Then immerse the obtained catalyst in 3 mol / L dilute HCl solution for pickling for 7 h to remove impurities. Centrifuge to collect the final black product FeV DACs, centrifuge 3 times with deionized water at a speed of 6000 r / min, collect the precipitate, and then dry it at 60 °C to obtain an iron-based dual single-atom catalyst, denoted as FeV DACs.

[0107] Carry out a pollutant degradation experiment on the FeV DACs of this example. Mix 5 mg of the synthesized FeV DACs with four sulfonamide antibiotic solutions at 10 mg / L (SDZ - sulfadiazine, SM2 - sulfamethazine, SMD - sulfamethoxydiazine, SMM - sulfamonomethoxine) in sequence, and add 0.1 mM PMS as an oxidant respectively. The results are as Figure 15 shown. It can be seen from Figure 15 that the removal rate of FeV DACs for SM2 - sulfamethazine is above 95% within 5 min.

[0108] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0109] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an iron-based double single-atom catalyst, characterized in that: The steps include: 1) mixing a mixed solution containing ferrocyanine tantalum with an alcohol solution of zinc nitrate to react to obtain ZnFe-ZIF; 2) mixing ZnFe-ZIF with NaCl solution to obtain a mixed solution, and using alcohol to precipitate NaCl@ZnFe-ZIF crystals from the mixed solution; 3) calcining the NaCl@ZnFe-ZIF crystals to obtain ZnFe-NC; 4) ZnFe-NC, a second metal salt and an alcohol are mixed, and after solid-liquid separation, the solid is calcined, acid-washed and dried in sequence to obtain an iron-based double single-atom catalyst.

2. The method for preparing an iron-based double single-atom catalyst according to claim 1, characterized in that: The preparation method of the mixed solution containing phthalocyanine iron in step 1) is: mixing phthalocyanine iron, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, dimethylimidazole and alcohol; The dosage ratio of the phthalocyanine iron, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, dimethylimidazole and alcohol is 0.1-0.2 mmol: 0.3-0.4 g: 2-3 g: 40-50 mL; The alcohol includes one or more of methanol, ethanol and n-butanol.

3. The method for preparing an iron-based double single-atom catalyst according to claim 2, characterized in that: The molar volume ratio of zinc nitrate to alcohol in the alcohol solution of zinc nitrate in step 1) is 5-6 mmol:40-50 mL; The alcohol includes one or more of methanol, ethanol and n-butanol.

4. The method for preparing an iron-based double single-atom catalyst according to any one of claims 1 to 3, characterized in that: The molar ratio of ferrocyanine in the mixed solution containing ferrocyanine to zinc nitrate in the alcohol solution of zinc nitrate in step 1) is 0.1-0.2:5-6; the reaction time in step 1) is 4-12 hours.

5. The method for preparing an iron-based double single-atom catalyst according to claim 4, characterized in that: The mass volume ratio of ZnFe-ZIF to NaCl solution in step 2) is 50-100 mg: 20-40 mL; The mass concentration of the NaCl solution is ≥30%; The calcination temperature in step 3) is 800-900° C., and the calcination time is 2-3 hours.

6. The method for preparing an iron-based double single-atom catalyst according to claim 5, characterized in that: In step 4), the ratio of ZnFe-NC, the second metal salt and the alcohol is 80 mg: 0.2-0.4 mmol: 40-50 mL; The second metal salt includes one or more of iron salt, manganese salt, vanadium salt and nickel salt; The alcohol includes one or more of methanol, ethanol and n-butanol.

7. The method for preparing an iron-based double single-atom catalyst according to claim 5 or 6, characterized in that: The calcination temperature in step 4) is 800-900°C and the calcination time is 2-3h; The acid solution used for pickling in step 4) includes hydrochloric acid and / or sulfuric acid; The molar concentration of the acid solution is 1 to 5 mol / L; The pickling time is 6 to 12 hours.

8. An iron-based double single-atom catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the iron-based double single-atom catalyst according to claim 8 in the treatment of organic wastewater.

10. An iron-based double single-atom catalyst coupled with a copper film, characterized in that: The method comprises the following preparation steps: mixing an iron-based double single-atom catalyst with a solvent to obtain a dispersion, and coating the dispersion on a copper film to obtain an iron-based double single-atom catalyst coupled copper film; The iron-based double single-atom catalyst is the iron-based double single-atom catalyst according to claim 8.

Images