阅读说明：本技术 一种利用ptfe部分疏水改性石墨毡阴极电合成过氧化氢的方法 (Method for cathodic electrosynthesis of hydrogen peroxide by using PTFE (polytetrafluoroethylene) partially-hydrophobic modified graphite felt ) 是由 周伟 高继慧 孙飞 孟晓晓 赵广播 秦裕琨 于 2020-12-22 设计创作，主要内容包括：一种基于PTFE部分疏水改性石墨毡阴极电合成过氧化氢的方法。首先用不同浓度的PTFE乳液浸没石墨毡,石墨毡经干燥后制得不同程度疏水改性的石墨毡电极。以疏水改性石墨毡为阴极,以具有优异析氧性能的电极为阳极,组装入电解槽中。当以直流电源供电时,疏水改性石墨毡阴极便可持续合成过氧化氢。与传统对石墨毡等碳基电极进行亲水改性的方法不同,本发明采用低成本的PTFE对石墨毡进行疏水改性,极大提高石墨毡电极合成过氧化氢的性能。使用本发明制得的电极成本低、易规模化应用。(A method for synthesizing hydrogen peroxide by using a PTFE (polytetrafluoroethylene) partially hydrophobic modified graphite felt cathode. Firstly, soaking graphite felts in PTFE emulsions with different concentrations, and drying the graphite felts to obtain graphite felt electrodes with different degrees of hydrophobic modification. The hydrophobic modified graphite felt is used as a cathode, and an electrode with excellent oxygen evolution performance is used as an anode and assembled into an electrolytic cell. When a direct current power supply is used for supplying power, the hydrophobic modified graphite felt cathode can continuously synthesize the hydrogen peroxide. Different from the traditional method for carrying out hydrophilic modification on carbon-based electrodes such as graphite felt and the like, the method adopts the PTFE with low cost to carry out hydrophobic modification on the graphite felt, thereby greatly improving the performance of synthesizing hydrogen peroxide by the graphite felt electrode. The electrode prepared by the invention has low cost and is easy to be applied in scale.)

1. A method for the cathodic synthesis of hydrogen peroxide by using a PTFE (polytetrafluoroethylene) partially hydrophobic modified graphite felt is characterized by comprising the following steps: the method comprises the following specific steps:

the method comprises the following steps: washing the graphite felt with deionized water, removing impurities and drying;

step two: immersing the graphite felt with PTFE emulsion for 1-2 h, taking out the graphite felt, and treating at 60-100 ℃ for 0.5-2 h to obtain a graphite felt cathode;

step three: and assembling the graphite felt cathode and the oxygen evolution anode into an electrolytic cell, keeping the stirring state, and synthesizing the hydrogen peroxide under the condition of constant pressure or constant current.

2. The process for the cathodic electrosynthesis of hydrogen peroxide using a PTFE partially hydrophobically modified graphite felt cathode according to claim 1, wherein: in the step one, the cleaning is ultrasonic cleaning for three times.

3. The process for the cathodic electrosynthesis of hydrogen peroxide using a PTFE partially hydrophobically modified graphite felt cathode according to claim 1, wherein: the concentration of the PTFE emulsion is 6-30%.

4. The process for the cathodic electrosynthesis of hydrogen peroxide using a PTFE partially hydrophobically modified graphite felt cathode according to claim 1, wherein: in the third step, the oxygen evolution anode is a Ti-based mixed metal oxide electrode; the electrolyte is Na with the concentration of 50 mM-200 mM₂SO₄The stirring speed of the solution is 50-500 rpm.

5. The method for the cathodic electrosynthesis of hydrogen peroxide using a PTFE partially hydrophobically modified graphite felt cathode according to claim 4, wherein: in the third step, the metal oxide is IrO₂Or Ru₂O₅。

6. The process for the cathodic electrosynthesis of hydrogen peroxide using a PTFE partially hydrophobically modified graphite felt cathode according to claim 1, wherein: in the third step, the current is 50-200 mA, and the voltage is 3-5V.

Technical Field

The invention belongs to the field of electrochemical synthesis of hydrogen peroxide as a green oxidant and sewage treatment, and particularly relates to a method for synthesizing hydrogen peroxide by using a PTFE (polytetrafluoroethylene) partially hydrophobic modified graphite felt cathode.

Background

Hydrogen peroxide (hydrogen peroxide) is considered to be one of the most important industrial chemicals in the world, and has wide application in the fields of pulping and papermaking, wastewater treatment, chemical synthesis, disinfection, textile and the like. The anthraquinone process which is the dominant industrial process at present is an energy-intensive process, and has complex flow and great pollution. As an alternative, based on O₂The technology for producing hydrogen peroxide by electrochemical reduction reaction is a green and safe technology, can realize small-scale and distributed hydrogen peroxide production, and has received particular attention from researchers in the fields of environment, energy, materials and the like in recent years. In the field of environmental remediation, the core of the electro-Fenton advanced oxidation technology is the hydrogen peroxide electrosynthesis technology. The development of an efficient hydrogen peroxide electrosynthesis technology is the key for developing an efficient electrosynthesis-Fenton technology to degrade organic pollutants in sewage.

The design and preparation of the high-efficiency cathode electrocatalyst are the basis for realizing the high-efficiency electrochemical synthesis of the hydrogen peroxide. Compared with various catalysts such as noble metals, metal complexes, metal oxides and the like, the carbon-based electrocatalyst has the advantages of low cost, controllable pores and chemical properties, stability, no toxicity and the like, and is widely concerned. Among them, the graphite felt material is particularly concerned because of its advantages such as mature production process, good conductivity, low cost, and the like, and modification methods thereof are continuously reported. In the oxygen doping treatment, various oxygen-containing functional groups can be introduced to the carbon surface, and the hydrophilicity of the electrode is improved, so that the oxygen reduction reaction and the yield of hydrogen peroxide are promoted. To date, many of the previous studies have focused particular attention on the modulation of the hydrophilicity of graphite felt.

However, while increasing hydrophilicity enhances mass transfer of oxygen across the electrode, the method is still based on the generation of hydrogen peroxide from dissolved oxygen. At ambient temperature and pressure, O₂Has low solubility (8.1 to 8.5mg/L at 25 ℃) and low diffusivity (1.96 to 2.56 x 10 at 25 ℃)^-9m²In s). Thereafter, researchers have proposed gas diffusion electrode structures comprising a gas diffusion layer,The catalyst layer and the current collector can form a gas-liquid-solid three-phase interface so as to overcome the problem of low dissolved oxygen concentration. Typically, the gas diffusion layer is hydrophobic and the catalytic layer is hydrophilic. However, the electrode has the problems of relatively complex structure, poor long-term stability, high energy consumption for pumping air/oxygen and the like, and the large-scale application is still a challenge. If the graphite felt electrode can be partially made hydrophobic by a simple method based on the graphite felt electrode, O in the solution can be made to be₂The bubbles are fixed on the local part of the graphite felt, so that an air-liquid-solid three-phase interface is directly constructed, the principle similar to a gas diffusion electrode is realized, and the high-efficiency hydrogen peroxide electrosynthesis is realized.

Disclosure of Invention

The invention aims to solve the problems of complex process flow, high energy consumption and great pollution in the prior anthraquinone method for producing hydrogen peroxide, and can efficiently reduce O at present₂The gas diffusion electrode for electrosynthesis of hydrogen peroxide has the problems of relatively complex electrode structure, poor long-term stability and the like, and provides a method for electrosynthesis of hydrogen peroxide by using a PTFE (polytetrafluoroethylene) partially hydrophobic modified graphite felt cathode.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a method for electrosynthesis of hydrogen peroxide by using a PTFE (polytetrafluoroethylene) partially hydrophobic modified graphite felt cathode comprises the following specific steps:

the method comprises the following steps: washing the graphite felt with deionized water, removing impurities and drying;

step two: immersing the graphite felt with PTFE emulsion for 1-2 h, taking out the graphite felt, and treating at 60-100 ℃ for 0.5-2 h to obtain a graphite felt cathode;

step three: and assembling the graphite felt cathode and the oxygen evolution anode into an electrolytic cell, keeping the stirring state, and synthesizing the hydrogen peroxide under the condition of constant pressure or constant current.

Compared with the prior art, the invention has the beneficial effects that: cheap PTFE and graphite felt are used as raw materials to prepare the PTFE partially hydrophobic modified graphite felt electrode, and other high-cost materials are not used in the preparation process, so that a gas-liquid-solid three-phase interface can be constructed in the electrode, and the yield of hydrogen peroxide is improved. In addition, the oxygen required in the process of synthesizing the hydrogen peroxide is provided in situ by the anodic electrochemical oxygen evolution reaction, and an additional oxygen supply device is not required. The invention has the advantages of cheap materials, simple preparation process, easy scale production and the like.

Drawings

FIG. 1 is a schematic diagram of a reaction apparatus for electrochemically synthesizing hydrogen peroxide by using a PTFE hydrophobically modified graphite felt cathode, wherein 1-DC power supply, 2-electrolytic cell, 3-PTFE hydrophobically modified graphite felt cathode, 4-oxygen evolution anode, and 5-Na₂SO₄Electrolyte, 6-magnetic stirrer;

FIG. 2 is a scanning electron micrograph of a pristine graphite felt;

FIG. 3 is a scanning electron micrograph of a graphite felt hydrophobically modified with a concentration of 6 wt% PTFE;

FIG. 4 is a scanning electron micrograph of a graphite felt hydrophobically modified with a 30 wt% concentration of PTFE;

FIG. 5 is a graph comparing the yield of hydrogen peroxide synthesized from a 6 wt% concentration PTFE hydrophobically modified graphite felt at different current levels;

FIG. 6 is a graph comparing the yield of hydrogen peroxide synthesized from a 6 wt% concentration PTFE hydrophobically modified graphite felt at various agitation rates;

FIG. 7 is a graph comparing the yield of hydrogen peroxide synthesized from 30 wt% PTFE hydrophobically modified graphite felt at different current levels;

FIG. 8 is a graph comparing the yield of hydrogen peroxide synthesized from 30 wt% concentration PTFE hydrophobically modified graphite felt at various agitation rates.

Detailed Description

The technical solutions of the present invention are further described below with reference to the drawings and the embodiments, but the present invention is not limited thereto, and modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

The first embodiment is as follows: the embodiment describes a method for cathodic synthesis of hydrogen peroxide by using a PTFE (polytetrafluoroethylene) partially-hydrophobic modified graphite felt, wherein PTFE emulsions with different concentrations are used for immersing the graphite felt and drying the graphite felt to prepare the hydrophobic modified graphite felt which can be directly used as a cathode for efficiently synthesizing the hydrogen peroxide; the method comprises the following specific steps:

the method comprises the following steps: washing the graphite felt with deionized water, removing impurities and drying;

step two: immersing the graphite felt for 1-2 h by using PTFE emulsion, taking out the graphite felt, and treating for 0.5-2 h at the temperature of 60-100 ℃ to obtain graphite felt cathodes subjected to hydrophobic modification in different degrees;

step three: the graphite felt cathode and the oxygen evolution anode are assembled into an electrolytic cell, the stirring state is kept, the operation is carried out under the condition of constant pressure or constant current, and the PTFE hydrophobic modified graphite felt cathode can synthesize hydrogen peroxide. The invention uses an anode with excellent oxygen evolution characteristics without adding air or oxygen as O₂And (4) source.

The second embodiment is as follows: in the method for the cathodic electrosynthesis of hydrogen peroxide by using the PTFE partially hydrophobically modified graphite felt, in the first step, the cleaning is ultrasonic cleaning for three times.

The third concrete implementation mode: in a method for cathodic synthesis of hydrogen peroxide by using a PTFE partially hydrophobic modified graphite felt, a PTFE emulsion with a concentration of 6-30% is prepared by using a petri dish and stirred uniformly.

The fourth concrete implementation mode: in the third step, the oxygen evolution anode is a Ti-based mixed metal oxide electrode; the electrode has excellent oxygen evolution performance, and can supply O to the cathode₂Used for hydrogen peroxide electrosynthesis, thereby needing no additional oxygen supply device. The electrolyte is Na with the concentration of 50 mM-200 mM₂SO₄The stirring speed of the solution is 50-500 rpm. Na in this concentration range₂SO₄The electrolyte can ensure that the solution has good conductivity.

The fifth concrete implementation mode: in the third step, the metal oxide is IrO₂Or Ru₂O₅。

The sixth specific implementation mode: in the third step, the current is 50-200 mA, and the voltage is 3-5V. The current and voltage can realize high-efficiency hydrogen peroxide electrosynthesis, and simultaneously, the problem that the yield of hydrogen peroxide is reduced due to ineffective decomposition of hydrogen peroxide in a solution under the condition of overhigh current or voltage is solved.

Example 1:

cutting a graphite felt with the thickness of 4mm into a square with the size of 2cm multiplied by 4cm, ultrasonically cleaning for 3 times by using deionized water and drying; immersing the graphite felt in 6 wt% PTFE emulsion; after 1h, taking out the graphite felt, putting the graphite felt into a hot air drying oven at 100 ℃, and maintaining for 0.5 h. The scanning electron microscope image of the original graphite felt is shown in the attached figure 2, and the scanning electron microscope image of the PTFE hydrophobic modified graphite felt is shown in the attached figure 3. Using Ti/IrO with the size of 3cm multiplied by 3cm₂/Ta₂O₅Is an anode. According to the schematic diagram of the apparatus shown in FIG. 1, cathodes and anodes were assembled into an electrolytic cell at 3cm intervals, wherein the electrolyte concentration was 50mM Na₂SO₄The solution was stirred at 1500 rpm. Constant current of 100mA is introduced, the electrolyte is rapidly stirred in the electrochemical reaction tank, and hydrogen peroxide is generated at the cathode of the PTFE hydrophobic modified graphite felt. As shown in FIG. 5, the synthesized hydrogen peroxide concentration at 50min is 44.13 mg/L.

Example 2:

cutting a graphite felt with the thickness of 4mm into a square with the size of 2cm multiplied by 4cm, ultrasonically cleaning for 3 times by using deionized water and drying; immersing the graphite felt in 30 wt% PTFE emulsion; after 1h, taking out the graphite felt, putting the graphite felt into a hot air drying oven at 100 ℃, and maintaining for 0.5 h. The scanning electron microscope image of the original graphite felt is shown in the attached figure 2, and the scanning electron microscope image of the PTFE hydrophobic modified graphite felt is shown in the attached figure 4. Using Ti/IrO with the size of 3cm multiplied by 3cm₂/Ta₂O₅Is an anode. According to the schematic diagram of the apparatus shown in FIG. 1, cathodes and anodes were assembled into an electrolytic cell at 3cm intervals, wherein the electrolyte concentration was 50mM Na₂SO₄The solution was stirred at 1500 rpm. Constant current of 100mA is introduced, and hydrogen peroxide is generated at the cathode of the PTFE hydrophobic modified graphite felt. As shown in FIG. 7, the concentration of synthesized hydrogen peroxide at 50min was 40.32 mg/L. CompareThe yield of the original graphite felt is improved by 6.3 times.

Example 3:

cutting a graphite felt with the thickness of 4mm into a square with the size of 2cm multiplied by 4cm, ultrasonically cleaning for 3 times by using deionized water and drying; immersing the graphite felt in 6 wt% PTFE emulsion; after 1.5h, the graphite felt is taken out and put into a hot air drying oven with the temperature of 80 ℃ and maintained for 1 h. The scanning electron microscope image of the original graphite felt is shown in the attached figure 2, and the scanning electron microscope image of the PTFE hydrophobic modified graphite felt is shown in the attached figure 3. Using Ti/IrO with the size of 3cm multiplied by 3cm₂/Ta₂O₅Is an anode. According to the schematic diagram of the apparatus shown in FIG. 1, cathodes and anodes were assembled into an electrolytic cell at 3cm intervals, wherein the electrolyte concentration was 50mM Na₂SO₄The solution was stirred at 1000 rpm. Constant current of 100mA is introduced, and hydrogen peroxide is generated at the cathode of the PTFE hydrophobic modified graphite felt. As shown in FIG. 6, the concentration of synthesized hydrogen peroxide at 50min was 29.73 mg/L.

Example 4:

cutting a graphite felt with the thickness of 4mm into a square with the size of 2cm multiplied by 4cm, ultrasonically cleaning for 3 times by using deionized water and drying; immersing the graphite felt in 30 wt% PTFE emulsion; and after 2 hours, taking out the graphite felt, putting the graphite felt into a hot air drying oven at 60 ℃, and maintaining for 2 hours. The scanning electron microscope image of the original graphite felt is shown in the attached figure 2, and the scanning electron microscope image of the PTFE hydrophobic modified graphite felt is shown in the attached figure 4. Using Ti/IrO with the size of 3cm multiplied by 3cm₂/Ta₂O₅Is an anode. According to the schematic diagram of the apparatus shown in FIG. 1, cathodes and anodes were assembled into an electrolytic cell at 3cm intervals, wherein the electrolyte concentration was 50mM Na₂SO₄The solution was stirred at 1000 rpm. Constant current of 100mA is introduced, and hydrogen peroxide is generated at the cathode of the PTFE hydrophobic modified graphite felt. As shown in FIG. 8, the concentration of synthesized hydrogen peroxide at 50min is 26.42 mg/L.

The above-mentioned contents are only for explaining the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.