Preparation method of modified graphite felt composite electrode capable of efficiently producing hydrogen

Abstract

The invention discloses a preparation method of a modified graphite felt composite electrode capable of efficiently producing hydrogen, which comprises the following steps: (1) cutting out a piece of graphite felt, soaking the graphite felt in acetone, absolute ethyl alcohol and deionized water in sequence, and then putting the graphite felt in a drying oven for drying treatment; (2) taking another beaker, adding polyquaternium and pyrrole into deionized water, and uniformly mixing and stirring; and (3) the pretreated graphite felt is added into a deionized water mixed solution to be fully soaked and stirred, then FeCl3 is added and uniformly stirred, polypyrrole generated by oxidation of FeCl3 is loaded on the graphite felt, and then the graphite felt is dried in a drying oven to obtain the modified electrode material. Aiming at the problems of high carbon source demand, high energy consumption, large sludge yield and the like in traditional municipal sewage treatment, hydrogen generated by electrolyzing water is applied to a bioelectrochemical system, so that the synergistic carbon reduction effect of reducing carbon source addition and reducing carbon dioxide emission is realized, and meanwhile, the denitrification nitrogen removal performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bioelectrochemical pollutant treatment, and in particular to a method for preparing a modified graphite felt composite electrode for efficient hydrogen production. Background Art

[0002] Domestic sewage in my country generally has a low carbon-nitrogen ratio. Urban sewage treatment plants usually need to add an external carbon source during the treatment process to meet the nitrogen removal in the denitrification process. The electrode biofilm system is a new denitrification water treatment technology developed by combining electrochemistry with microbiology. The hydrogen produced by water electrolysis is utilized by hydrogen autotrophic denitrifying bacteria attached to the carrier, achieving the purpose of denitrification while reducing the addition of carbon sources. In addition, hydrogen is a clean energy source. Compared with the carbon dioxide produced by the addition of external carbon sources, the water produced by its metabolism has no secondary pollution to the environment. Therefore, there is an urgent need to apply the hydrogen produced by water electrolysis to the bioelectrochemical system to address the problems of high carbon source demand, high energy consumption, and large sludge production in traditional municipal sewage treatment, so as to achieve the synergistic carbon reduction effect of reducing carbon source addition and reducing carbon dioxide emissions, while improving the denitrification nitrogen removal performance. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and to provide a method for solving the problems of high carbon source demand, high energy consumption, and large sludge production in traditional municipal sewage treatment. The method uses the electrolysis of water to generate hydrogen and applies it to a bioelectrochemical system, thereby achieving the synergistic carbon reduction effect of reducing carbon source addition and reducing carbon dioxide emissions, while improving the denitrification nitrogen removal performance.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for preparing a modified graphite felt composite electrode for efficient hydrogen production, comprising the following steps:

[0006] (1) Cut a piece of graphite felt, soak it in acetone, anhydrous ethanol and deionized water in sequence, and then put the graphite felt in an oven for drying;

[0007] (2) Take another beaker, add polyquaternium salt and pyrrole into deionized water and mix well;

[0008] (3) The pretreated graphite felt is added to a deionized water mixed solution and fully soaked and stirred, and then FeCl3 is added and stirred evenly, so that the polypyrrole produced by FeCl3 oxidation is loaded on the graphite felt, and then dried in an oven to obtain a modified electrode material.

[0009] Furthermore, in step (1), the length and width of the graphite felt are both 3 cm, and the soaking time of the graphite felt in acetone, anhydrous ethanol and deionized water is 3 h.

[0010] Furthermore, in step (1), the drying temperature of the oven is 60° C., and the drying time is 12-24 hours.

[0011] Furthermore, in step (2), the volume of the polyquaternium salt is 100 mL, and the concentration is 51 g / L; the volume of the pyrrole is 100 mL, and the concentration is 0.1-0.2 mol / L.

[0012] Furthermore, in step (2), the volume of deionized water is 100 mL, the stirring rate is 300 rpm, and the stirring time is 1-3 hours.

[0013] Furthermore, in step (3), the graphite felt is immersed in the mixed solution and stirred for 2-4 hours, the stirring rate is 300 rpm, and the drying temperature of the electrode after uniform loading is 60°C.

[0014] Furthermore, in step (3), the FeCl3 concentration in the deionized water mixed solution is 0.1 mol / L, the stirring time after adding FeCl3 is 1-2 h, and the stirring rate is 300 rpm.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The composite electrode preparation method of the present invention is simple, low-cost, and pollution-free. The addition of polyquaternary ammonium salt effectively improves the hydrophilicity and biocompatibility of the graphite felt electrode, while the addition of polypyrrole effectively enhances its electrical conductivity. Ultimately, the graphite felt electrode effectively reduces its overhydrogen potential, significantly enhancing the hydrogen production performance of the bioelectrochemical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a cyclic voltammetry curve of the graphite felt electrode of the present invention;

[0018] Figure 2 is a Tafel plot of the graphite felt electrode of the present invention;

[0019] Figure 3 The linear sweep voltammetry curve of the graphite felt electrode of the present invention is shown in FIG.

[0020] Figure 4 This is a graph analyzing the denitrification performance of the graphite felt electrode of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0022] Example 1

[0023] A method for preparing a modified graphite felt composite electrode for efficient hydrogen production, comprising the following steps:

[0024] (1) Cut a piece of graphite felt with a length and width of 3 cm, soak it in acetone, anhydrous ethanol and deionized water for 3 hours, and then put it in an oven for drying. The drying temperature of the oven is 60℃ and the drying time is 12-24 hours.

[0025] (2) Take another beaker, add polyquaternium salt and pyrrole into deionized water and mix and stir evenly. The volume of polyquaternium salt is 100 mL, the concentration is 51 g / L, the volume of pyrrole is 100 mL, the concentration is 0.1-0.2 mol / L, the volume of deionized water is 100 mL, the stirring rate is 300 rpm, and the stirring time is 1-3 hours.

[0026] (3) The pretreated graphite felt is added to a deionized water mixed solution and fully soaked and stirred at a stirring rate of 300 rpm for 2-4 hours. FeCl3 is then added and stirred evenly to make the FeCl3 concentration in the deionized water mixed solution 0.1 mol / L. The stirring time is 1-2 hours and the stirring rate is 300 rpm. The polypyrrole produced by FeCl3 oxidation is loaded on the graphite felt and then dried in an oven at a drying temperature of 60°C to obtain a modified electrode material.

[0027] like Figure 1 The figure shows the cyclic voltammetry curve analysis of the modified graphite felt composite electrode. The test steps are as follows:

[0028] Electrode Selection: Based on the research system and objectives, select an appropriate working electrode, such as a glassy carbon electrode or platinum electrode; a reference electrode, such as a saturated calomel electrode or a silver / silver chloride electrode; and a counter electrode, typically an inert electrode such as a platinum wire electrode. Its function is to form a circuit with the working electrode, conduct current, and induce an electrochemical reaction at the working electrode. In this example, a glassy carbon electrode and a modified graphite felt composite electrode were used as the working electrode for comparison. A silver / silver chloride electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode.

[0029] Prepare solution: Prepare 0.01 M phosphate buffer solution, ensuring that the solution is homogeneous and free of impurities.

[0030] Install electrodes: Install the glassy carbon electrode, silver / silver chloride electrode, platinum sheet electrode; and the graphite felt composite electrode, silver / silver chloride electrode, platinum sheet electrode, and two sets of electrode combinations in the three-electrode system, ensuring that the relative positions between the electrodes are appropriate and that the electrodes are in good contact with the solution.

[0031] After completing the above preparations, connect the three-electrode system to the electrochemical workstation. After confirming that the electrodes are properly connected to the instrument, set the parameters. Set the scan parameters in the electrochemical workstation software, including a starting potential of 1.5 V, an ending potential of -1.5 V, a scan speed of 0.05 V / s, and a scan number of 2.

[0032] After setting the above parameters, start data acquisition and start the potential scanning program. The electrochemical workstation will automatically record the data of the current on the working electrode changing with the potential. After the scan is completed, the two sets of data collected will be exported for subsequent analysis and processing. Figure 1 It can be seen that the conductivity of the modified graphite felt composite electrode is 4 times that of the unmodified glassy carbon electrode, and the conductivity of the modified graphite felt composite electrode is significantly improved.

[0033] Example 2

[0034] like Figure 2 The following is the Tafel curve analysis of the modified graphite felt composite electrode. The test steps are as follows:

[0035] In this embodiment, a glassy carbon electrode and a modified graphite felt composite electrode were selected as the working electrode for comparison, a silver / silver chloride electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode.

[0036] Prepare solution: Prepare 0.01 M phosphate buffer solution, ensuring that the solution is homogeneous and free of impurities.

[0037] Install electrodes: Install the glassy carbon electrode, silver / silver chloride electrode, platinum sheet electrode; and the graphite felt composite electrode, silver / silver chloride electrode, platinum sheet electrode, and two sets of electrode combinations in the three-electrode system, ensuring that the relative positions between the electrodes are appropriate and that the electrodes are in good contact with the solution.

[0038] After completing the above preparations, connect the three-electrode system to the electrochemical workstation. After confirming that the electrodes are properly connected to the instrument, set the parameters. Set the scan parameters in the electrochemical workstation software, including a starting potential of 1.5 V, an ending potential of -1.5 V, a scan speed of 0.01 V / s, and a scan number of 1.

[0039] After setting the above parameters, start data acquisition and start the potential scanning program. The electrochemical workstation will automatically record the current response on the working electrode. After the scan is completed, the two sets of collected data will be exported for subsequent analysis and processing. Figure 2 It can be seen that the exchange current density of the glassy carbon electrode is 5.896×10-4A / cm 2 The exchange current density of the graphite felt composite electrode is 2.122×10-2A / cm 2 , which proves that the modified graphite felt composite electrode greatly improves its electrical conductivity, thereby accelerating the hydrogen production rate.

[0040] Example 3

[0041] like Figure 3The figure shows the linear sweep voltammetric curve analysis of the modified graphite felt composite electrode. The test steps are as follows:

[0042] Working Electrode: Electrode materials that participate in hydrogenotrophic denitrification reactions can be selected, such as electrocatalytically active metal electrodes such as platinum, palladium, or nickel-modified electrodes. In this example, a nickel-modified electrode and a modified graphite felt composite electrode were used as the working electrode for comparison. A silver / silver chloride electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode.

[0043] Prepare solution: Prepare 0.01 M phosphate buffer solution, ensuring that the solution is homogeneous and free of impurities.

[0044] Install electrodes: Install the platinum modified electrode, silver / silver chloride electrode, platinum sheet electrode; graphite felt composite electrode, silver / silver chloride electrode, platinum sheet electrode, and two sets of electrode combinations in the three-electrode system respectively, ensuring that the relative positions between the electrodes are appropriate and the electrodes are in good contact with the solution.

[0045] Determine the starting potential and ending potential according to the experimental purpose and research system. In this embodiment, the starting potential is set to 1.5V and the ending potential is set to -1.5V. The scanning rate is usually selected between 10-1000mV / s. The scanning speed is 0.01V / s, and this parameter can be adjusted according to the experimental results. Set the number of scan circles to 1 circle. After confirming that the parameter settings are correct, start the electrochemical workstation for linear scanning. During the scanning process, the workstation will gradually change the potential of the working electrode according to the set scanning rate, and at the same time measure the corresponding current value, thereby obtaining a current-potential curve, that is, a linear scanning voltammetric curve. From Figure 3 It can be seen that the graphite felt composite electrode is 1mA / cm 2 The overhydrogen potential value is 71mV, which is much lower than the commonly used nickel electrode potential value of 500mV. The graphite felt composite electrode significantly reduces the overhydrogen potential of the bioelectrochemical system, ensuring the hydrogen production efficiency while greatly reducing the required energy consumption.

[0046] Example 4

[0047] like Figure 4 Shown is the denitrification performance analysis of the modified graphite felt composite electrode. The test steps are:

[0048] Set up two groups of experiments, respectively prepare two groups of the same COD / N 3 solution (50mg / L NO3 - -N and 150mg / LCOD), and the unmodified and modified electrode materials were placed in the BER system to explore their denitrification efficiency. In this example, the unmodified electrode material was a nickel electrode, and the modified electrode material was a graphite felt composite electrode.

[0049] The constant current was 5mA, 10mA and 20mA respectively and the concentrations of nitrate, nitrite and total nitrogen in the effluent during the stable period were measured. Figure 4 It can be seen that when the current values are 10mA and 20mA, the hydrogen autotrophic denitrification system of the graphite felt composite electrode reduces the concentrations of nitrate nitrogen, nitrite nitrogen and total nitrogen compared with the nickel electrode, and improves the nitrogen removal performance of the system.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a modified graphite felt composite electrode for efficient hydrogen production, characterized in that: Here are the steps: (1) Cut a piece of graphite felt, soak it in acetone, anhydrous ethanol and deionized water in sequence, and then put the graphite felt in an oven for drying; (2) Take another beaker, add polyquaternium salt and pyrrole into deionized water and mix well; (3) The pretreated graphite felt is added to a deionized water mixed solution and fully soaked and stirred, and then FeCl3 is added and stirred evenly, so that the polypyrrole produced by FeCl3 oxidation is loaded on the graphite felt, and then dried in an oven to obtain a modified electrode material.

2. The method for preparing a modified graphite felt composite electrode for efficient hydrogen production according to claim 1, characterized in that: In step (1), the length and width of the graphite felt are both 3 cm, and the soaking time of the graphite felt in acetone, anhydrous ethanol and deionized water is 3 h.

3. The method for preparing a modified graphite felt composite electrode for efficient hydrogen production according to claim 2, characterized in that: The drying temperature of the oven in step (1) is 60° C., and the drying time is 12-24 hours.

4. The method for preparing a modified graphite felt composite electrode for efficient hydrogen production according to claim 1, characterized in that: In step (2), the volume of the polyquaternium salt is 100 mL, and the concentration is 51 g / L; the volume of the pyrrole is 100 mL, and the concentration is 0.1-0.2 mol / L.

5. The method for preparing a modified graphite felt composite electrode for efficient hydrogen production according to claim 4, characterized in that: In step (2), the volume of deionized water is 100 mL, the stirring rate is 300 rpm, and the stirring time is 1-3 hours.

6. The method for preparing a modified graphite felt composite electrode for efficient hydrogen production according to claim 1, characterized in that: In step (3), the graphite felt is immersed in the mixed solution and stirred for 2-4 hours, the stirring rate is 300 rpm, and the drying temperature of the electrode after uniform loading is 60°C.

7. The method for preparing a modified graphite felt composite electrode for efficient hydrogen production according to claim 6, characterized in that: The FeCl3 concentration in the deionized water mixed solution in step (3) is 0.1 mol / L, and the stirring time after adding FeCl3 is 1-2 h, and the stirring rate is 300 rpm.

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