Preparation method and application of in-situ electrochemical reconstruction of iron-manganese bimetallic electrode material

Abstract

The application relates to a preparation method and application of an in-situ electrochemical reconstruction iron-manganese bimetal electrode material, belonging to the technical field of material synthesis and wastewater treatment. First, iron-manganese prussian blue is prepared by using a hydrothermal method, then the iron-manganese prussian blue is loaded on carbon paper, and the iron-manganese prussian blue is coupled with the carbon paper by anodic oxidation in an ascorbic acid solution to form iron-manganese organic framework nanosheets which are in-situ grown on carbon fibers. The electrode after in-situ growth is used as an anode of a three-electrode system, a low voltage of 1.1V is added, and stirring is continuously carried out to realize removal of bisphenol A in water. The iron-manganese organic framework nanosheet material in-situ grown on the carbon fibers which is synthesized by using an innovative method can realize efficient removal of bisphenol A in water under low voltage in combination with electrooxidation.

Description

TECHNICAL FIELD

[0001] The application 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, in particular to an iron-manganese bimetallic electrode material obtained by growing iron-manganese organic framework nanosheets on carbon fibers through electro-oxidation, and application of the iron-manganese bimetallic electrode material to electro-catalytic removal of bisphenol A in water. BACKGROUND

[0002] Emerging pollutants have caused great harm to the environment due to their environmental persistence and non-degradability, and traditional wastewater treatment processes cannot effectively remove these pollutants. Bisphenol A, as an endocrine disruptor produced in industrial and agricultural production processes, widely exists in the environment, and the existence of bisphenol A has caused immeasurable harm to human health. Based on the electro-catalytic advanced oxidation process technology, which 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 existing in the environment, such as adsorption method, biological method, photocatalysis, Fenton method, etc. However, these water treatment technologies have some defects such as difficulty in regenerating adsorption materials, inability to completely remove organic pollutants, harsh conditions for microbial survival, complex process, high cost, limited application scale, etc., while the advanced oxidation technology based on transition metal 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 shows super-high electro-catalytic removal ability of pollutants, but it is not stable under anodic oxidation conditions and may undergo phase transition, and its catalytic ability is often limited, which has poor practical applicability. Therefore, there is still a lack of efficient, economical and environmentally friendly bisphenol A treatment technology. SUMMARY

[0005] In view of the above defects in the prior art, the application provides a preparation method and application of an in-situ electrochemically reconstructed iron-manganese bimetallic electrode material, which is synthesized by an innovative method and grows on carbon fibers, and can realize efficient removal of bisphenol A in water at low voltage in combination with electro-oxidation.

[0006] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0007] A preparation method of an in-situ electrochemically reconstructed iron-manganese bimetallic electrode material, comprising the following steps:

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

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

[0010] Step c, electro-oxidation in ascorbic acid solution to obtain iron-manganese organic framework nanosheet grown in-situ on carbon fiber, i.e. iron-manganese bimetallic electrode material.

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

[0012] a1: adding iron nitrate, manganese nitrate and potassium hydroxide with a molar ratio of 0.1-7.5:0.1-7.5 mmol:0.1-7.5 mmol in formamide, and stirring uniformly;

[0013] a2: transferring the solution into a high-pressure reaction kettle, the reaction time is 5-15 h, and the reaction temperature is 160-180℃; after the reaction is completed, cooling to room temperature to obtain an iron-manganese Prussian blue (Fe-Mn PBA) suspension;

[0014] a3: ethanol centrifugal washing is performed on the iron-manganese Prussian blue (Fe-Mn PBA) suspension, the washing product is dried in an oven, and grinding is performed to obtain iron-manganese Prussian blue (Fe-Mn PBA).

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

[0016] b1: dispersing the iron-manganese Prussian blue (Fe-Mn PBA) obtained in step a with ethanol, loading on carbon paper, and drying.

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

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

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

[0020] d1: placing the iron-manganese organic framework nanosheet material (FeMn@CP) as an electrode into a degradation system based on a three-electrode system, and electrocatalytically degrading organic pollutant wastewater.

[0021] As a preferred technical scheme of the present application, the organic pollutants subjected to electrocatalytic degradation are bisphenol A, the electrolyte used in electrocatalytic degradation is 0.1 mol / L of Na2SO4, the anode is the prepared iron-manganese organic framework nanosheet electrode, the cathode is a platinum sheet, and the electrode distance is 2 cm. The voltage in electrocatalytic degradation is 0.8-1.5 V.

[0022] Compared with the prior art, the present application has the beneficial effects of:

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

[0024] 2. The present application realizes efficient and rapid removal of bisphenol A at low voltage, has high removal rate and short time consumption.

[0025] 3. The removal efficiency is less affected by common inorganic anions and humic acid and the like, and bisphenol A can also be basically removed in Chaohu water and tap water. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The present application is a flowchart of the method for preparing the iron-manganese organic framework nanosheet material and removing bisphenol A in water.

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

[0028] Figure 3 The present application is the scanning electron microscope photograph of the synthesized iron-manganese Prussian blue material.

[0029] Figure 4 The present application is the scanning electron microscope photograph of the synthesized iron-manganese organic framework nanosheet material.

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

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

[0032] Figure 7The removal rate of bisphenol A in water when the voltage is applied is not the same; 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 The removal rate of bisphenol A in water when the dosage of bisphenol A is not the same; wherein the concentration of sodium sulfate is 0.1 mol / L, and the initial pH value of the solution is about 5.6.

[0034] Figure 9 The removal rate of bisphenol A in water when the initial pH value of the solution is not the same; wherein the concentration of bisphenol A is 20 mg / L, and the concentration of sodium sulfate is 0.1 mol / L. DETAILED DESCRIPTION

[0035] The application will be further described in conjunction with the embodiments and the accompanying drawings.

[0036] Please refer to Figure 1 As shown in the drawings, the application proposes a preparation method and application of an in-situ electrochemical reconstruction of a ferromanganese bimetal electrode material, specifically, an iron-manganese organic framework nanosheet is grown in-situ on a carbon fiber by electro-oxidation to obtain a ferromanganese bimetal electrode material, which is applied to electro-catalytic removal of bisphenol A in water to achieve removal of bisphenol A in water.

[0037] Example 1

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

[0039] First, 15 mL of formamide, 1.5 mmol of ferric nitrate (nine hydrates) and 6 mmol of manganese nitrate are added to a clean 50 mL beaker, stirred to dissolve, then 15 mL of formamide and 7.5 mmol of potassium hydroxide are added to a second clean 50 mL beaker, stirred to dissolve. Mix the solutions in the two beakers to get a black mixed solution, stir uniformly and then transfer to a Teflon-lined stainless steel pressure cooker, keep at 170℃ for 12h to get a red-brown precursor (Fe-Mn PBA suspension), wash with ethanol and dry to get the iron-manganese prussian blue material (Fe-Mn PBA).

[0040] The cut carbon paper (2x2 cm 2 ) is pre-soaked in ultrapure water and ultrasonically cleaned, dried, then a proper amount of iron-manganese prussian blue material is dispersed with ethanol and dropped onto the carbon paper, dried and electro-oxidized in an ascorbic acid solution at 1.3V for 3h to generate the iron-manganese organic framework nanosheet material (FeMn@CP) grown in-situ on the carbon fiber, the FeMn@CP material loading on the carbon paper is 1 mg / cm 2 .

[0041] Figure 2 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 embodiment. Figure 3 , 4 The scanning electron microscope photos of the iron-manganese prussian blue material and the iron-manganese organic framework nanosheet material synthesized by the method described in this embodiment, respectively. It can be seen from the figure that the obtained iron-manganese organic framework nanosheet is in a sheet flower structure.

[0042] Example 2

[0043] Application of the iron-manganese organic framework nanosheet material (FeMn@CP) in removing bisphenol A in water:

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

[0045] Example 3

[0046] Application of the iron-manganese organic framework nanosheet material (FeMn@CP) in removing bisphenol A in water under actual water body:

[0047] In order to obtain the effect of the iron-manganese organic framework nanosheet material (FeMn@CP) in removing bisphenol A under actual water body, the deionized water is replaced with tap water or filtered Chaohu water in Hefei City and Feicui Lake water in Hefei City based on Example 2, and other conditions remain unchanged. The removal rate of bisphenol A can reach more than 80% within 2 h.

[0048] Example 4

[0049] Application of the iron-manganese organic framework nanosheet material (FeMn@CP) in removing bisphenol A in water after multiple cycles:

[0050] The iron-manganese organic framework nanosheet material can be washed and dried after use according to the scheme described in Example 2, and the process of Example 2 is repeated once to be regarded as one cycle. After being used and cycled for 9 times, the iron-manganese organic framework nanosheet material is activated by sodium sulfate for 1 h, and still can achieve 90% removal of bisphenol A within 2 h for the tenth time.

[0051] Example 5

[0052] Application of the iron-manganese organic framework nanosheet material (FeMn@CP) in removing bisphenol A in water under different iron-manganese ratios:

[0053] ​The iron-manganese Prussian blue with different iron-manganese ratios (1:0, 1:3, 1:4, 1:6, 1:9, 0:1) prepared according to the method of Example 1 was loaded on carbon paper, and after electro-oxidation in an ascorbic acid solution, the carbon paper was placed as an anode into a solution with 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 according to the scheme described in this example is shown in the figure. It can be seen that as the manganese ratio gradually increases, the degradation rate gradually increases, 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 exhibits the fastest degradation performance of bisphenol A.

[0054] Example 6

[0055] Application of iron-manganese organic framework nanosheet material (FeMn@CP) in removal of bisphenol A in water under different voltage conditions:

[0056] The iron-manganese organic framework nanosheet material grown in situ on carbon fibers obtained in Example 1 was placed as an anode into a solution with 20 mg / L bisphenol A as the treatment object, the electrolyte was 0.1 mol / L sodium sulfate, different voltages (0.8 V-1.5 V) were applied, and the reaction was carried out at 600 rpm for 2 h. The results are shown in Figure 7 . Figure 7 The reaction rate changes when different voltages are applied according to the scheme described in this example. It can be seen from the figure that as the voltage gradually increases, the degradation rate of the iron-manganese organic framework nanosheet gradually increases, and 0.9 V can achieve 100% removal of bisphenol A, and the degradation has high efficiency at 1.1 V.

[0057] Example 7

[0058] Application of iron-manganese organic framework nanosheet material (FeMn@CP) in removal of bisphenol A in water under different bisphenol A dosage conditions:

[0059] The iron-manganese organic framework nanosheet material grown in situ on carbon fibers obtained in Example 1 was placed as an anode into 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 the electrocatalysis was carried out at 600 rpm for 2 h to degrade bisphenol A. As the concentration of bisphenol A increases, the degradation rate gradually decreases (as shown in the figure). Figure 8

[0060] Example 8

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

[0062] ​The iron-manganese organic framework nanosheet material grown in-situ on carbon fiber obtained from Example 1 is used as an anode in a solution with 20 mg / L bisphenol A as the treatment object, the electrolyte is 0.1 mol / L sodium sulfate, adjusted to different pH values (5-11), a voltage of 1.1V is applied, and the reaction is carried out at 600 rpm for 2h to degrade bisphenol A. With the change of pH, the degradation rate of iron-manganese organic framework nanosheet is reduced, but the degradation rate is reduced to 69% at pH 11, and the pH values at other pH values can basically achieve 100% removal of bisphenol A within 2h. Therefore, the iron-manganese organic framework nanosheet prepared by the present application exhibits excellent bisphenol A degradation performance (as shown in Figure 9

[0063] Example 9

[0064] Application of iron-manganese organic framework nanosheet material (FeMn@CP) in removal of bisphenol A in water in the presence of common inorganic anions and humic acid:

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

[0066] The above content is only an example and description of the concept of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as the modifications or supplements do not deviate from the concept of the present application or exceed the scope defined by the present application, and should belong to the protection scope of the present application.​

Claims

1. A preparation method of in-situ electrochemical reconfiguration of iron-manganese bimetallic electrode material, characterized in that, Comprising the following steps: Step a, preparing iron manganese prussian blue by hydrothermal method; a1: adding iron nitrate, manganese nitrate and potassium hydroxide in a molar ratio of 0.1-7.5:0.1-7.5:0.1-7.5 in formamide, and stirring uniformly; a2: transferring the solution into a high-pressure reaction kettle, the reaction time is 5-15 h, and the reaction temperature is 160-180 DEG C; after the reaction is completed, it is cooled to room temperature to obtain an iron manganese prussian blue suspension; a3: performing ethanol centrifugal washing on the iron manganese prussian blue suspension, drying the washing product in an oven, grinding, and obtaining iron manganese prussian blue; Step b, dispersing the iron manganese prussian blue with ethanol, and then dropping on carbon paper, and drying; Step c, the carbon paper loaded with the material is placed in an ascorbic acid solution, and is subjected to electro-oxidation at 0.8-1.5 V for 1-6 h, washed, dried, to obtain the iron-manganese organic framework nanosheet material grown in situ on the carbon fiber, wherein the loading amount of the iron-manganese prussian blue is 0.25-2 mg / cm 2 .

2. The use of the method for preparing in-situ electrochemically restructured iron-manganese bimetallic electrode material according to claim 1, characterized in that, The iron manganese organic framework nanosheet material is used as an electrode in a degradation system based on a three-electrode system, and is used for electrocatalytic degradation of organic pollutant wastewater.

3. Use according to claim 2, wherein the compound is ###0002### The organic pollutant electrocatalytically degraded is bisphenol A, the electrolyte used in electrocatalytic degradation is 0.1 mol / L Na2SO4, the anode is the prepared iron manganese organic framework nanosheet electrode, the cathode is a platinum sheet, and the electrode distance is 2 cm.

4. The use according to claim 2, wherein The voltage in electrocatalytic degradation is 0.8-1.5 V.

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