Preparation method of iron-based high-entropy micro-nano alloy Fenton catalyst

Abstract

The present invention discloses a method for preparing an iron-based high-entropy micro-nano alloy Fenton catalyst. The method comprises the following steps: first, activating a pure copper electrode; then preparing an electrolyte solution of ferrous sulfate / copper sulfate / cobalt sulfate / nickel sulfate / zinc sulfate / manganese sulfate; adding a chelating agent, a hydrogen evolution inhibitor, and an auxiliary agent to the electrolyte solution; using the activated pure copper electrode as the cathode and a ring-shaped graphite electrode as the anode; constructing an electrodeposition device comprising the cathode, an anion exchange membrane, and a transparent quartz reaction tank base, the electrodeposition device containing the electrolyte; connecting the positive electrode of a power supply to the anion exchange membrane and the negative electrode of the power supply to the cathode; immersing the anode in the electrolyte; setting a current density reaction, and depositing iron-based high-entropy micro-nano alloy powder at the cathode; and finally collecting the catalyst powder. The method of the present invention exhibits excellent catalytic performance for PMS over a wide pH range.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and in particular relates to a method for preparing an iron-based high-entropy micro-nano alloy Fenton catalyst. Background Art

[0002] Fenton technology, a type of advanced oxidation technology, uses catalysts to generate free radicals during the reaction, achieving a broad-spectrum oxidation effect on most organic compounds and possessing a wide range of applications. However, current Fenton oxidation technologies often suffer from poor pollutant degradation under alkaline conditions, and the elution of trivalent iron ions in the reaction system, producing iron sludge, leads to secondary environmental pollution and reduced degradation performance upon repeated use. Therefore, in the development of efficient heterogeneous catalysts, the preparation of Fenton-like catalyst materials that are inexpensive, readily available, highly stable, and exhibit high catalytic performance over a wide pH range holds significant application value in the water treatment field. Summary of the Invention

[0003] To overcome the shortcomings of the existing technology, the present invention provides a method for preparing an iron-based high-entropy micro-nano alloy Fenton catalyst. The method comprises the following steps: first, activating a pure copper electrode; then preparing an electrolyte solution of ferrous sulfate / copper sulfate / cobalt sulfate / nickel sulfate / zinc sulfate / manganese sulfate; adding a chelating agent, a hydrogen evolution inhibitor, and an auxiliary agent to the electrolyte; using the activated pure copper electrode as the cathode and a ring-shaped graphite electrode as the anode; constructing an electrodeposition apparatus comprising the cathode, an anion exchange membrane, and a transparent quartz reaction tank base, the electrodeposition apparatus containing the electrolyte; connecting the positive electrode of a power supply to the anion exchange membrane and the negative electrode of the power supply to the cathode; immersing the anode in the electrolyte; setting a current density reaction, and depositing iron-based high-entropy micro-nano alloy powder at the cathode; and finally collecting the catalyst powder. The method of the present invention exhibits excellent catalytic performance against PMS over a wide pH range.

[0004] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0005] Step 1: Activate the electrode;

[0006] Select a pure copper electrode, polish it with sandpaper to remove surface impurities, then soak it in acetone to remove grease, rinse it with deionized water, and then pickle it in a mixed acid of HCl / HNO3 with a molar ratio of 5:1 to remove the oxide layer on the surface of the pure copper electrode;

[0007] Step 2: Prepare ferrous sulfate / copper sulfate / cobalt sulfate / nickel sulfate / zinc sulfate / manganese sulfate electrolyte;

[0008] Step 3: adding a complexing agent, a hydrogen evolution inhibitor, and an auxiliary agent to the electrolyte;

[0009] Step 4: Use the activated pure copper electrode as the cathode and the ring graphite electrode as the anode;

[0010] The electrodeposition device is composed of a cathode, an anion exchange membrane and a transparent quartz reaction tank base. The electrodeposition device contains electrolyte. The positive pole of the power supply is connected to the anode, and the negative pole of the power supply is connected to the cathode. The anion exchange membrane is immersed in the electrolyte.

[0011] Step 5: Set the initial current density to 1A / dm 2 , react for 10s; then increase the current density to twice the initial current density, and further react for 10s, at which time the iron-based high entropy micro-nano alloy powder is deposited at the cathode;

[0012] Step 6: Collecting catalyst powder;

[0013] The cathode was flushed with ethanol to remove the prepared iron-based high entropy micro-nano alloy powder, which was then washed three times with deionized water and ethanol respectively, centrifuged, and dried at 65°C in a vacuum oven.

[0014] Preferably, the pure copper electrode has a length of 100 mm and a diameter of 2 mm.

[0015] Preferably, the specific step of polishing with sandpaper to remove surface impurities is: polishing with 400, 800, and 1200 mesh sandpaper in sequence to remove surface impurities.

[0016] Preferably, the Fe in the ferrous sulfate / copper sulfate / cobalt sulfate / nickel sulfate / zinc sulfate / manganese sulfate electrolyte is 2+ 、Cu 2+ 、Co 2+ 、Ni 2+ 、Zn 2+ 、Mn 2+ The total ion concentration remains unchanged at 5.0 mol / L, of which Fe 2+ As the main element, accounting for 70% to 90%, Cu 2+ 、Co 2+ 、Ni 2+ 、Zn 2+ 、Mn 2+ The atomic ratio is 1% to 7%.

[0017] Preferably, the complexing agent includes one or more of sodium hexametapolyphosphate, citric acid, sodium lauryl sulfate, and boric acid, with a total concentration of 5g to 80g / L; the hydrogen evolution inhibitor includes one or more of ethanol, ethylene glycol, and glycerol, with a total concentration of 10 to 50ml / L; and the auxiliary agent includes one or more of saccharin and lactic acid, with a total concentration of 0.1-1mol / L.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The catalytic performance of transition metals such as Cu, Co, Mn, Ni, and Zn: Transition metals such as Cu, Co, Mn, Ni, and Zn have multiple redox states and are less susceptible to passivation reactions than Fe. They have good catalytic performance for PMS in a wide pH range.

[0020] 2. Synergistic effect of Cu, Co, Mn, Ni, Zn and Fe: Fe and transition metals such as Cu, Co, Mn, Ni, and Zn form a weak galvanic cell, which can react with PMS faster than single Fe to produce active oxygen species free radicals, thereby degrading pollutants.

[0021] 3. Transition metals improve the performance of Fe: Cu, Co, Mn, Ni, Zn and other highly reducing transition metals can undergo redox reactions with Fe3+ to produce Fe2+, thereby further promoting more Fe2+ to react with PMS to generate active oxygen species. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A diagram of the electrodeposition apparatus.

[0023] Figure 2 This is the XRD pattern of iron-based high-entropy micro-nano alloy.

[0024] Figure 3 This is the morphology of a pure iron alloy obtained without other transition metal sources.

[0025] Figure 4 The ratio of Cu, Co, Mn, Ni and Zn sources is 1-3.5%, and the Fe90Mx (1<x≤3.5) iron-based high entropy micro-nano alloy morphology is obtained.

[0026] Figure 5 The ratio of Cu, Co, Mn, Ni and Zn sources is 3.5-5%, and the Fe80Mx (3.5<x≤5) iron-based high entropy micro-nano alloy morphology is obtained.

[0027] Figure 6 The source ratio of Cu, Co, Mn, Ni and Zn is 5-7%, and the Fe70Mx (5<x≤7) iron-based high entropy micro-nano alloy morphology is obtained.

[0028] Figure 7 Degradation performance of iron and different iron-based high entropy micro-nano alloys in a pH neutral environment.

[0029] In the figure, 1- cathode, 2- anode, 3- electrolyte, 4- anion exchange membrane, 5- positive electrode of power supply, 6- negative electrode of power supply. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and examples.

[0031] A method for preparing an iron-based high-entropy micro-nano alloy Fenton catalyst, the technical solution is as follows:

[0032] 1. Activate the electrode. Select a pure copper electrode with a length of 100 mm and a diameter of 2 mm. Polish it with 400, 800, and 1200 grit sandpaper to remove surface impurities. Then soak it in acetone to remove grease. Rinse it with deionized water and then pickle it in a mixed acid of HCl (5 mol / L) and HNO3 (1 mol / L) with a molar ratio of 5:1 to remove the oxide layer on the surface of the pure copper electrode.

[0033] 2. Prepare ferrous sulfate / copper sulfate / cobalt sulfate / nickel sulfate / zinc sulfate / manganese sulfate electrolyte. Among them, Fe in the electrolyte 2+ 、Cu 2+ 、Co 2+ 、Ni 2+ 、Zn 2+ 、Mn 2+ The total ion concentration remains unchanged at 5.0 mol / L, of which Fe 2+ As the main element, accounting for 70% to 90%, Cu 2+ 、Co 2+ 、Ni 2+ 、Zn 2+ 、Mn 2+ The atomic ratio is 1% to 7%.

[0034] 3. Add a complexing agent, hydrogen evolution inhibitor, and auxiliary agent to the electrolyte. The selected complexing agent includes one or more of sodium hexametapolyphosphate, citric acid, sodium lauryl sulfate, and boric acid, with a total concentration of 5g to 80g / L. The hydrogen evolution inhibitor includes one or more of ethanol, ethylene glycol, and glycerol, with a total concentration of 10 to 50ml / L. The auxiliary agent includes one or more of saccharin and lactic acid, with a total concentration of 0.1-1mol / L. The presence of the auxiliary agent can act as a buffer, change the kinetic growth of the high-entropy alloy, and increase the electrodeposition rate.

[0035] 4. Use the activated pure copper electrode as cathode and the annular graphite electrode as anode. The specific device is as follows: Figure 1 shown.

[0036] 5. Set the current density to 1A / dm 2 , react for 10s; then increase to twice the initial current density, and further react for 10s, at this time the iron-based high entropy micro-nano alloy powder is deposited at the cathode.

[0037] 6. Collect the catalyst powder. Rinse the pure copper cathode with ethanol to remove the prepared high entropy alloy. Rinse with deionized water and ethanol three times, centrifuge, and dry under vacuum at 65°C.

[0038] Example:

[0039] The prepared powder was tested for its ability to degrade rhodamine B. A 100 mL deionized water solution of 10 ppm rhodamine B was prepared and adjusted to neutrality with dilute sulfuric acid and sodium hydroxide solution. 5 mg of the prepared catalyst was added to the solution and mechanically stirred to disperse it. Then, a PMS solution was added to achieve a PMS concentration of 1 mmol / L. The temperature was set at 25°C, and the change in rhodamine B concentration over time after the addition of PMS was measured.

[0040] Table 1 shows the energy spectrum results of high-entropy micro-nano alloys prepared in electrolytes with different metal ion ratios. The data in the table show that this high-entropy alloy is primarily composed of iron, and the proportions of the different metals in the sample differ from the concentration ratios in the electrolyte. This is due to the different redox properties of the different metal ions.

[0041] Table 1

[0042]

[0043] Figure 2 The XRD pattern of the iron-based high-entropy micro-nano alloy shows that the dendrites are still dominated by the Fe crystal phase. However, as the Cu, Co, Mn, Ni, and Zn source content increases, the strongest peak of Fe decreases and shifts. This is because the Cu, Co, Mn, Ni, and Zn metal atoms enter the Fe lattice, causing the interplanar spacing to change.

[0044] Figure 3 The pure iron alloy morphology obtained without other transition metal sources has a size between 3-8μm.

[0045] Figure 4 The ratio of Cu, Co, Mn, Ni and Zn sources is 1-3.5%, and the Fe 90 M x(1＜x≤3.5) The morphology of iron-based high-entropy micro-nano alloys, with sizes ranging from 3-8μm.

[0046] Figure 5 The ratio of Cu, Co, Mn, Ni and Zn sources is 3.5-5%, and the Fe 80 M x(3.5＜x≤5) The morphology of iron-based high-entropy micro-nano alloys, with sizes ranging from 3-8μm.

[0047] Figure 6 The ratio of Cu, Co, Mn, Ni and Zn sources is 5-7%, and the Fe 70 M x(5＜x≤7) The morphology of iron-based high-entropy micro-nano alloys, with sizes ranging from 3-8μm.

[0048] Figure 7The degradation performance of iron and different iron-based high-entropy micro-nano alloys in a pH neutral environment can be seen. With the increase of the proportion of Cu, Co, Mn, Ni and Zn sources, the degradation performance is significantly improved.

Claims

1. A method for preparing an iron-based high-entropy micro-nano alloy Fenton catalyst, characterized in that: The steps include: Step 1: Activate the electrode; Select a pure copper electrode, polish it with sandpaper to remove surface impurities, then soak it in acetone to remove grease, rinse it with deionized water, and then pickle it in a mixed acid of HCl / HNO3 with a molar ratio of 5:1 to remove the oxide layer on the surface of the pure copper electrode; Step 2: Prepare ferrous sulfate / copper sulfate / cobalt sulfate / nickel sulfate / zinc sulfate / manganese sulfate electrolyte; Fe in the ferrous sulfate / copper sulfate / cobalt sulfate / nickel sulfate / zinc sulfate / manganese sulfate electrolyte 2+ 、Cu 2+ 、Co 2+ 、Ni 2+ 、Zn 2+ 、Mn 2+ The total ion concentration remains unchanged at 5.0 mol / L, of which Fe 2+ As the main element, accounting for 70% to 90%, Cu 2+ 、Co 2+ 、Ni 2+ 、Zn 2+ 、Mn 2+ The atomic ratio is 1% to 7%; Step 3: adding a complexing agent, a hydrogen evolution inhibitor, and an auxiliary agent to the electrolyte; Step 4: Use the activated pure copper electrode as the cathode and the ring graphite electrode as the anode; The electrodeposition device is composed of a cathode, an anion exchange membrane and a transparent quartz reaction tank base, and the electrodeposition device is filled with electrolyte; The positive electrode of the power supply is connected to the anode, and the negative electrode of the power supply is connected to the cathode; the anion exchange membrane is immersed in the electrolyte; Step 5: Set the initial current density to 1A / dm 2 , react for 10s; then increase the current density to twice the initial current density, and further react for 10s, at which time the iron-based high entropy micro-nano alloy powder is deposited at the cathode; Step 6: Collecting catalyst powder; The cathode was flushed with ethanol to remove the prepared iron-based high entropy micro-nano alloy powder, which was then washed three times with deionized water and ethanol respectively, centrifuged, and dried at 65°C in a vacuum oven.

2. The method for preparing an iron-based high-entropy micro-nano alloy Fenton catalyst according to claim 1, characterized in that: The dimensions of the pure copper electrode are 100 mm in length and 2 mm in diameter.

3. The method for preparing an iron-based high-entropy micro-nano alloy Fenton catalyst according to claim 1, characterized in that: The specific steps of polishing with sandpaper to remove surface impurities are: polishing with 400, 800 and 1200 mesh sandpaper in sequence to remove surface impurities.

4. The method for preparing an iron-based high-entropy micro-nano alloy Fenton catalyst according to claim 1, characterized in that: The complexing agent includes one or more of sodium hexametapolyphosphate, citric acid, sodium lauryl sulfate, and boric acid, with a total concentration of 5g to 80g / L; the hydrogen evolution inhibitor includes one or more of ethanol, ethylene glycol, and glycerol, with a total concentration of 10 to 50ml / L; and the auxiliary agent includes one or more of saccharin and lactic acid, with a total concentration of 0.1-1mol / L.

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