Preparation method and application of in-situ electrochemical reconstructed ferro-manganese bimetallic electrode material

Abstract

The invention discloses a preparation method and application of an in-situ electrochemical reconstructed ferro-manganese bimetallic electrode material, and belongs to the technical field of material synthesis and wastewater treatment. The preparation method comprises the following steps: firstly, preparing ferro-manganese Prussian blue by using a hydrothermal method, then loading the ferro-manganese Prussian blue onto carbon paper, and coupling the ferro-manganese Prussian blue with the carbon paper through anodic oxidation in an ascorbic acid solution to form the ferro-manganese organic framework nanosheet grown on the carbon fiber in situ. And taking the electrode after in-situ growth as an anode of a three-electrode system, applying 1.1 V low voltage and continuously stirring so as to remove bisphenol A in water. The iron-manganese organic framework nanosheet material which is synthesized by an innovative method and grows on the carbon fiber in situ is combined with electrooxidation, so that bisphenol A in water at low voltage can be efficiently removed.

Description

Technical Field

[0001] The present invention belongs to the technical field of material synthesis and wastewater treatment, and relates to a preparation method and application of an in-situ electrochemically reconstructed iron-manganese bimetallic electrode material. Specifically, electro-oxidation is used to make iron-manganese organic skeleton nanosheets in-situ grow on carbon fibers to obtain an iron-manganese bimetallic electrode material, which is then used for electrocatalytic removal of bisphenol A in water. Background Art

[0002] Emerging pollutants have caused great harm to the environment due to their environmental persistence and difficulty in degradation, and traditional wastewater treatment processes cannot effectively remove these pollutants. Among them, bisphenol A is an endocrine disruptor produced in industrial and agricultural production processes and is widely present in the environment. The presence of bisphenol A has caused inestimable harm to human health. Electrocatalytic advanced oxidation process technology has attracted widespread attention due to its ability to eliminate these pollutants under environmental conditions. Therefore, how to efficiently remove bisphenol A is of great significance.

[0003] So far, people have explored many methods to remove bisphenol A in the environment, such as adsorption, biological methods, photocatalysis, Fenton-like methods, etc. However, these water treatment technologies have some defects, such as difficulty in regenerating adsorbent materials, inability to completely remove organic pollutants, harsh living conditions for microorganisms, complex processes, high costs, and limited application scale. Advanced oxidation technology based on transition metals can overcome these problems.

[0004] Iron-manganese compounds have attracted much attention in catalytic research due to their environmental friendliness, low cost and high catalytic efficiency. Iron-manganese Prussian blue exhibits an ultra-high electrocatalytic ability to remove pollutants, but it is unstable under anodic oxidation conditions and may undergo phase changes. Its catalytic ability is often limited and its practical applicability is poor. Therefore, there is still a lack of efficient, economical and environmentally friendly bisphenol A treatment technology. Summary of the invention

[0005] In view of the above-mentioned defects existing in the prior art, the present invention provides a preparation method and application of an in-situ electrochemically reconstructed iron-manganese bimetallic electrode material. The iron-manganese organic framework nanosheet material grown in situ on carbon fiber synthesized by an innovative method is combined with electro-oxidation to achieve efficient removal of bisphenol A in water under low voltage.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing an in-situ electrochemically reconstructed iron-manganese bimetallic electrode material comprises the following steps:

[0008] Step a, preparing iron-manganese Prussian blue by hydrothermal method;

[0009] Step b, dispersing the iron-manganese Prussian blue with ethanol, then dropping it onto carbon paper, and drying it;

[0010] Step c: electro-oxidation is carried out in an ascorbic acid solution to obtain iron-manganese organic framework nanosheets grown in situ on carbon fibers, namely, iron-manganese bimetallic electrode materials.

[0011] As a preferred technical solution of the present invention, in the preparation method, the specific steps of step a are as follows:

[0012] a1: Add iron nitrate, manganese nitrate and potassium hydroxide in a molar ratio of 0.1-7.5:0.1-7.5 mmol:0.1-7.5 mmol to formamide and stir evenly;

[0013] a2: transferring the solution to a high-pressure reactor, reacting for 5 to 15 hours at a temperature of 160 to 180°C; after the reaction is completed, cooling to room temperature to obtain an iron-manganese Prussian blue (Fe-Mn PBA) suspension;

[0014] a3: washing the Fe-Mn Prussian blue (Fe-Mn PBA) suspension by centrifugation with ethanol, drying the washed product in an oven, and grinding to obtain Fe-Mn Prussian blue (Fe-Mn PBA).

[0015] As a preferred technical solution of the present invention, in the preparation method, the specific steps of step b are as follows:

[0016] b1: The iron-manganese Prussian blue (Fe-Mn PBA) obtained in step a is dispersed in ethanol, loaded on carbon paper, and dried.

[0017] As a preferred technical solution of the present invention, in the preparation method, the specific steps of step c are as follows:

[0018] c1: Place the carbon paper loaded with the material in an ascorbic acid solution, electro-oxidize at 0.8-1.5V for 1-6h, wash, and dry to obtain an iron-manganese organic framework nanosheet material (FeMn@CP) grown in situ on carbon fiber, wherein the loading amount of iron-manganese Prussian blue is 0.25-2mg / cm 2 .

[0019] The present invention also proposes the application of the in-situ electrochemical reconstruction of the iron-manganese bimetallic electrode material, the steps of which are as follows:

[0020] d1: The iron-manganese organic framework nanosheet material (FeMn@CP) is placed as an electrode in a degradation system based on a three-electrode system to electrocatalytically degrade organic pollutants in wastewater.

[0021] As a preferred technical solution of the present invention, the organic pollutant to be electrocatalytically degraded is bisphenol A, the electrolyte used in the electrocatalytic degradation is 0.1 mol / L Na2SO4, the anode is the prepared iron-manganese organic skeleton nanosheet electrode, the cathode is a platinum sheet, the electrode distance is 2 cm, and the voltage during the electrocatalytic degradation is 0.8-1.5V.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The present invention can synthesize iron-manganese organic skeleton nanosheets grown in situ on carbon fibers through simple hydrothermal and electro-oxidation, which can be directly used for anode electrocatalytic degradation of organic pollutants and has good conductivity and strong stability.

[0024] 2. It realizes efficient and rapid removal of bisphenol A under low voltage, with high removal rate and short time consumption.

[0025] 3. Experiments have confirmed that the removal efficiency is less affected by common inorganic anions and humic acid and other substances, and bisphenol A can be basically removed in Chaohu water and tap water. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a schematic diagram of the process of preparing the iron-manganese organic framework nanosheet material and removing bisphenol A from water.

[0027] Figure 2 Phase characterization results of the synthesized iron-manganese Prussian blue material (before) and iron-manganese organic framework nanosheet material (after).

[0028] Figure 3 This is a scanning electron microscope image of the synthesized iron-manganese Prussian blue material.

[0029] Figure 4 This is a scanning electron microscope photo of the synthesized iron-manganese organic framework nanosheet material.

[0030] Figure 5 The removal rate of bisphenol A in water during electrocatalytic degradation of the synthesized iron-manganese organic framework nanosheet material; the concentration of bisphenol A is 20 mg / L and the material loading on the carbon paper is 1 mg / cm 2 , the sodium sulfate concentration was 0.1 mol / L, and the initial pH of the reaction was about 5.6.

[0031] Figure 6 is the removal rate of bisphenol A in water at different iron-manganese ratios; wherein, the concentration of bisphenol A is 20 mg / L, the concentration of sodium sulfate is 0.1 mol / L, and the initial pH value of the solution is about 5.6.

[0032] Figure 7is the removal rate of bisphenol A in water when different voltages are applied; wherein, the concentration of bisphenol A is 20 mg / L, the concentration of sodium sulfate is 0.1 mol / L, and the initial pH value of the solution is about 5.6.

[0033] Figure 8 is the removal rate of bisphenol A in water when the dosage of bisphenol A is different; among them, the concentration of sodium sulfate is 0.1 mol / L, and the initial pH value of the solution is about 5.6.

[0034] Fig. 9 is the removal rate of bisphenol A in water when the initial pH value of the solution is different; among them, the concentration of bisphenol A is 20 mg / L and the concentration of sodium sulfate is 0.1 mol / L. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with embodiments and drawings.

[0036] See also Figure 1 As shown, the present invention proposes a preparation method and application of an in-situ electrochemically reconstructed iron-manganese bimetallic electrode material, specifically, electro-oxidation is used to make iron-manganese organic skeleton nanosheets in situ grow on carbon fibers to obtain an iron-manganese bimetallic electrode material, which is applied to the electrocatalytic removal of bisphenol A in water to achieve the removal of bisphenol A in water.

[0037] Example 1

[0038] Preparation of iron-manganese organic framework nanosheet materials (FeMn@CP):

[0039] First, add 15 mL of formamide, 1.5 mmol of iron nitrate (nonahydrate) and 6 mmol of manganese nitrate to a clean 50 mL beaker, stir to dissolve, then add 15 mL of formamide and 7.5 mmol of potassium hydroxide to a second clean 50 mL beaker, stir to dissolve. Mix the solutions in the two beakers to obtain a black mixed solution, stir well and transfer to a Teflon-lined stainless steel autoclave, keep at 170 ° C for 12 hours to obtain a reddish brown precursor (Fe-Mn PBA suspension), wash with ethanol and dry to obtain an iron-manganese Prussian blue material (Fe-Mn PBA).

[0040] Cut carbon paper (2×2cm 2 ) was pre-immersed in ultrapure water for ultrasonic cleaning and drying. Subsequently, an appropriate amount of FeMn Prussian blue material was dispersed in ethanol and then added dropwise to the carbon paper. After drying, it was electro-oxidized in ascorbic acid solution at 1.3 V for 3 h to generate FeMn organic framework nanosheet material (FeMn@CP) grown in situ on carbon fiber. The loading amount of FeMn@CP material on carbon paper was 1 mg / cm 2 .

[0041] Figure 2 These are the phase characterization results of the iron-manganese Prussian blue material and the iron-manganese organic framework nanosheet material synthesized by the method described in this example. Figure 3 , 4 The scanning electron microscope pictures of the iron-manganese Prussian blue material and the iron-manganese organic framework nanosheet material synthesized by the method described in this example are shown in Figure 1. It can be seen from the figure that the obtained iron-manganese organic framework nanosheet is a flower structure.

[0042] Example 2

[0043] Application of FeMn@CP in removing bisphenol A from water:

[0044] The iron-manganese organic framework nanosheet material in situ grown on carbon fiber obtained in Example 1 was used as an anode and placed in a solution containing 20 mg / L bisphenol A as the treatment object. The electrolyte was 0.1 mol / L sodium sulfate, the voltage was 1.1 V, and the reaction was carried out at 600 rpm for 2 h. The removal rate of bisphenol A can reach 100% ( Figure 5 The carbon paper was washed with ultrapure water and then dried and recovered.

[0045] Example 3

[0046] Application of FeMn@CP in removing bisphenol A from water in actual water bodies:

[0047] In order to obtain the effect of FeMn@CP on removing bisphenol A in actual water, the deionized water was replaced with tap water or filtered water from Chaohu Lake in Hefei or Emerald Lake in Hefei on the basis of Example 2, and other conditions remained unchanged. The removal rate of bisphenol A within 2 hours can reach more than 80%.

[0048] Example 4

[0049] Application of FeMn@CP in removing bisphenol A from water after multiple cycles:

[0050] The iron-manganese organic skeleton nanosheet material can be washed and dried after use according to the scheme described in Example 2, and repeating the process of Example 2 once is considered as one cycle. The iron-manganese organic skeleton nanosheet material used and cycled 9 times is activated with sodium sulfate for 1 hour, and 90% of bisphenol A can still be removed within 2 hours for the tenth time.

[0051] Example 5

[0052] Application of FeMn@CP in removing bisphenol A from water with different iron-manganese ratios:

[0053] According to the method of Example 1, iron-manganese Prussian blue with different iron-manganese ratios (1:0, 1:3, 1:4, 1:6, 1:9, 0:1) was prepared and loaded on carbon paper. After electro-oxidation in ascorbic acid solution, the carbon paper was placed as an anode in a solution containing 20 mg / L bisphenol A as the treatment object, a voltage of 1.1 V was applied, and the reaction was carried out at 600 rpm for 2 h. The results are shown in Figure 6 . Figure 6 The removal rate of bisphenol A in water by the iron-manganese organic framework nanosheet material synthesized with different iron-manganese ratios according to the scheme described in this embodiment. As can be seen from the figure, as the manganese ratio gradually increases, the degradation rate gradually accelerates, but after reaching a certain ratio, the catalytic rate decreases. Under the same catalyst dosage, the material with an iron-manganese ratio of 1:4 shows the fastest performance in degrading bisphenol A.

[0054] Example 6

[0055] Application of FeMn@CP in removing bisphenol A from water under different voltage conditions:

[0056] The iron-manganese organic framework nanosheet material in situ grown on carbon fiber obtained in Example 1 was placed as an anode in a solution containing 20 mg / L bisphenol A as the treatment object, and the electrolyte was 0.1 mol / L sodium sulfate. Different voltages (0.8V-1.5V) were applied and reacted at 600 rpm for 2 hours. The results are shown in Figure 7 . Figure 7 According to the scheme described in this embodiment, the reaction rate changes when the applied voltage is different. As can be seen from the figure, as the voltage gradually increases, the degradation rate of the iron-manganese organic framework nanosheets gradually increases, 0.9V can achieve 100% removal of bisphenol A, and the degradation is highly efficient at 1.1V.

[0057] Example 7

[0058] Application of FeMn@CP in removing bisphenol A from water under different bisphenol A dosage conditions:

[0059] The iron-manganese organic framework nanosheet material in situ grown on carbon fiber obtained in Example 1 was placed as an anode in a solution with different concentrations (5-100 mg / L) of bisphenol A as the treatment object, the electrolyte was 0.1 mol / L sodium sulfate, a voltage of 1.1 V was applied, and electrocatalysis was carried out at 600 rpm for 2 h to degrade bisphenol A. As the concentration of bisphenol A increased, the degradation rate gradually decreased ( Figure 8 shown).

[0060] Example 8

[0061] Application of manganese oxides of different phases in removing bisphenol A from water under different pH conditions:

[0062] The iron-manganese organic skeleton nanosheet material in situ grown on carbon fiber obtained in Example 1 was used as an anode and placed in a solution with 20 mg / L bisphenol A as the treatment object, the electrolyte was 0.1 mol / L sodium sulfate, adjusted to different pH values ​​(5-11), applied a voltage of 1.1 V, and reacted at 600 rpm for 2 hours to degrade bisphenol A. As the pH changes, the degradation rate of the iron-manganese organic skeleton nanosheet decreases, but except for the pH value of 11 when the degradation rate drops to 69%, other pH values ​​can basically achieve 100% removal of bisphenol A within 2 hours. Therefore, the iron-manganese organic skeleton nanosheet prepared by the present invention exhibits excellent bisphenol A degradation performance (such as Fig. 9 shown).

[0063] Example 9

[0064] Application of FeMn@CP in removing bisphenol A from water in the presence of common inorganic anions and humic acid:

[0065] The iron-manganese organic framework nanosheet material in situ grown on carbon fiber obtained in Example 1 was placed as an anode in a solution containing 20 mg / L bisphenol A as the treatment object, and a voltage of 1.1 V was applied. The electrocatalysis was carried out at 600 rpm for 2 h to degrade BPA. Common inorganic anions and humic acid were added for electrocatalysis, and the addition amount was 10 mmol / L. In addition to adding PO4 3- The removal rate of bisphenol A was only 50% after 2 hours of treatment with ions; under the influence of other anions and humic acid, 100% removal of bisphenol A could be basically achieved within 2 hours.

[0066] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing an in-situ electrochemically reconstructed iron-manganese bimetallic electrode material, characterized in that: The following steps are involved: Step a, preparing iron-manganese Prussian blue by hydrothermal method; Step b, dispersing the iron-manganese Prussian blue with ethanol, then dropping it onto carbon paper, and drying it; Step c: electro-oxidation is carried out in an ascorbic acid solution to obtain iron-manganese organic framework nanosheets grown in situ on carbon fibers, namely, iron-manganese bimetallic electrode materials.

2. The preparation method according to claim 1, characterized in that Step a: The specific steps are as follows: a1: Add iron nitrate, manganese nitrate and potassium hydroxide in a molar ratio of 0.1-7.5:0.1-7.5 mmol:0.1-7.5 mmol to formamide and stir evenly; a2: transferring the solution to a high-pressure reactor, reacting for 5 to 15 hours at a temperature of 160 to 180°C; after the reaction is completed, cooling to room temperature to obtain an iron-manganese Prussian blue (Fe-Mn PBA) suspension; a3: washing the Fe-Mn Prussian blue (Fe-Mn PBA) suspension by centrifugation with ethanol, drying the washed product in an oven, and grinding to obtain Fe-Mn Prussian blue (Fe-Mn PBA).

3. The preparation method according to claim 1, characterized in that: Step b: The specific steps are as follows: b1: The iron-manganese Prussian blue (Fe-Mn PBA) obtained in step a is dispersed in ethanol, loaded on carbon paper, and dried.

4. The preparation method according to claim 1, characterized in that: Step c: The specific steps are as follows: c1: Place the carbon paper loaded with the material in an ascorbic acid solution, electro-oxidize at 0.8-1.5V for 1-6h, wash, and dry to obtain an iron-manganese organic framework nanosheet material (FeMn@CP) grown in situ on carbon fiber, wherein the loading amount of iron-manganese Prussian blue is 0.25-2mg / cm 2 .

5. Application of the method according to any one of claims 1 to 4 in preparing in-situ electrochemically reconstructed iron-manganese bimetallic electrode materials, characterized in that: Here are the steps: d1: The iron-manganese organic framework nanosheet material (FeMn@CP) is placed as an electrode in a degradation system based on a three-electrode system to electrocatalytically degrade organic pollutants in wastewater.

6. The use according to claim 5, characterized in that The organic pollutant for electrocatalytic degradation is bisphenol A. The electrolyte used for electrocatalytic degradation is 0.1 mol / L Na2SO4, the anode is the prepared iron-manganese organic skeleton nanosheet electrode, the cathode is a platinum sheet, and the electrode distance is 2 cm.

7. The use according to claim 5, characterized in that The voltage during electrocatalytic degradation is 0.8~1.5V.

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