Electro-Fenton system cathode, electro-Fenton system and application thereof

Abstract

The present invention provides an electro-Fenton system cathode, an electro-Fenton system, and its application, belonging to the field of electro-Fenton advanced oxidation water treatment. The present invention provides an electro-Fenton system cathode, comprising: from bottom to top, a columnar polymer aerogel, an electrode sheet containing through holes, and a columnar electrode active material embedded in a shell; the electrode sheet containing through holes is in contact with the columnar electrode active material; the pore size of the columnar polymer aerogel is 0.01 to 10 μm; the columnar electrode active material includes a covalent organic framework material or a modified material containing a covalent organic framework material. The electro-Fenton system cathode of the present invention can be placed horizontally, and the cathode is prepared using a columnar polymer aerogel with a suitable pore size to improve the degradation effect; the hydrogen peroxide generated by the cathode reduction reaction generates hydroxyl radicals that degrade pollutants in water under the catalysis of the covalent organic framework material. The electro-Fenton system prepared therefrom does not produce iron sludge during use and does not require pH adjustment.

Description

Technical Field

[0001] The present invention relates to the field of modification, in particular to an electro-Fenton system cathode, an electro-Fenton system and applications thereof. Background Art

[0002] Electro-Fenton technology is a commonly used advanced oxidation technology widely used in wastewater treatment. It uses hydrogen peroxide and iron ions to generate highly reactive hydroxyl radicals, which rapidly degrade organic pollutants.

[0003] The distribution or diffusion of gases within the electro-Fenton technology electrode significantly affects the generation of H2O2. This distribution or diffusion depends on the electrode's pore structure. If the pore structure cannot be controlled, air or oxygen entering the electrode will be concentrated in a localized area under the influence of gas pressure, especially when the electrode is placed vertically. This results in inconsistent electrochemical reduction reactions at different locations on the electrode surface, which in turn reduces current efficiency and affects pollutant degradation.

[0004] In addition, Fe added to the reaction system during the electro-Fenton reaction 2+ Iron sludge is inevitable. To avoid the generation of iron sludge, it is necessary to adjust and control the pH of the reaction system, which makes the operation complicated. Summary of the Invention

[0005] The purpose of the present invention is to provide an electro-Fenton system cathode, an electro-Fenton system and applications thereof. The electro-Fenton system prepared by the electro-Fenton system cathode of the present invention has good pollutant degradation effect, does not produce iron sludge, does not require pH adjustment, and is simple to operate.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides an electro-Fenton system cathode, comprising:

[0008] From bottom to top, the columnar polymer aerogel, the electrode sheet with through holes and the columnar electrode active material embedded in the shell;

[0009] The electrode sheet containing through holes is in contact with the columnar electrode active material;

[0010] The pore size of the columnar polymer aerogel is 0.01 to 10 μm;

[0011] The columnar electrode active material includes a covalent organic framework material or a modified material containing a covalent organic framework material.

[0012] Preferably, the electrode sheet containing through holes includes a ring-shaped electrode sheet.

[0013] Preferably, the columnar polymer aerogel includes one or more of polypropylene aerogel, polyethylene aerogel, polystyrene aerogel and polyvinyl chloride aerogel.

[0014] Preferably, the covalent organic framework material comprises a melamine / terephthalaldehyde covalent organic framework material.

[0015] Preferably, the preparation method of the melamine / terephthalaldehyde covalent organic framework material comprises the following steps:

[0016] Melamine, terephthalaldehyde and a polar organic solvent are mixed and subjected to a solvothermal reaction to obtain the melamine / terephthalaldehyde covalent organic framework material.

[0017] Preferably, the molar ratio of melamine to terephthalaldehyde is 1:1-3.

[0018] Preferably, the temperature of the solvent thermal reaction is 160-210° C., and the time is 8-72 hours.

[0019] Preferably, the columnar electrode active material is fixed by a fastening clamp.

[0020] The present invention also provides an electro-Fenton system, comprising a power supply, an anode, a cathode, and a reaction cell; the cathode is the electro-Fenton system cathode described in the above scheme, and the electrode sheet containing a through hole in the electro-Fenton system cathode is connected to the negative electrode of the power supply via a wire;

[0021] The reaction tank comprises a water inlet, a water outlet and an air inlet;

[0022] In terms of spatial orientation, the anode is below the water outlet;

[0023] The cathode of the electro-Fenton system is connected to the gas inlet.

[0024] The present invention also provides the application of the electro-Fenton system described in the above solution in degrading organic matter.

[0025] The present invention provides an electro-Fenton system cathode, comprising: a columnar polymer aerogel, an electrode sheet containing through holes, and a columnar electrode active material embedded in a housing from bottom to top; the electrode sheet containing through holes is in contact with the columnar electrode active material; the columnar polymer aerogel has a pore size of 0.01 to 10 μm; and the columnar electrode active material comprises a covalent organic framework material or a modified material containing a covalent organic framework material. The electro-Fenton system cathode of the present invention can be placed horizontally. The cathode is prepared using a columnar polymer aerogel with a suitable pore size, allowing oxygen or air to be evenly dispersed across the entire cathode surface, enhancing the mass transfer area and efficiency of air or oxygen, thereby improving the degradation effect of the electro-Fenton system prepared thereby. The hydrogen peroxide generated by the cathode reduction reaction can, under the catalysis of the covalent organic framework material, generate hydroxyl radicals that degrade pollutants in water. Therefore, the electro-Fenton system prepared thereby does not require the addition of ferrous salts, does not generate iron sludge, and does not require pH adjustment during use.

[0026] The cathodes currently used or reported are generally one-piece structures, and their manufacturing, assembly, and use processes do not take into account issues such as replacement of the various components. The present invention, however, uses a fastening clamp for fixing, making the cathode of the present invention a detachable structure, which facilitates assembly and replacement, and the cathode structure of the present invention is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the cathode of the electro-Fenton system in the embodiment of the present invention and the comparative example;

[0028] Figure 2 Schematic diagram of the structure of the electro-Fenton system in the embodiment of the present invention and the comparative example;

[0029] Figure 3 The degradation results of the electro-Fenton system of Example 1 and Comparative Example 1 are shown;

[0030] Figure 4 The experimental results of the cyclic stability of the electro-Fenton system in Example 1 are as follows;

[0031] Figure 5 These are the results of the methylene blue degradation experiments using the electro-Fenton system in Examples 1 to 3. DETAILED DESCRIPTION

[0032] The present invention provides an electro-Fenton system cathode, comprising:

[0033] From bottom to top, the columnar polymer aerogel, the electrode sheet with through holes and the columnar electrode active material embedded in the shell;

[0034] The electrode sheet containing through holes is in contact with the columnar electrode active material;

[0035] The pore size of the columnar polymer aerogel is 0.01 to 10 μm;

[0036] The columnar electrode active material includes a covalent organic framework material or a modified material containing a covalent organic framework material.

[0037] In the present invention, the diameters of the columnar polymer aerogel and columnar electrode active material, and the outer diameter of the electrode sheet containing through holes are preferably the same as the inner diameter of the housing; the electrode sheet containing through holes preferably comprises a ring-shaped electrode sheet. The use of a ring-shaped electrode ensures the reliability of circuit connectivity.

[0038] In the present invention, the thickness ratio of the columnar polymer aerogel to the columnar electrode active material is preferably 1 to 3:1.

[0039] In the present invention, the columnar polymer aerogel preferably includes one or more of polypropylene aerogel, polyethylene aerogel, polystyrene aerogel and polyvinyl chloride aerogel; the pore size of the columnar polymer aerogel is 0.01 to 10 μm.

[0040] In the present invention, the method for preparing the columnar polymer aerogel preferably comprises the following steps:

[0041] After the polymer is mixed with natural oil and fat for swelling, the obtained swollen polymer is cooled, washed and dried in sequence to obtain the columnar polymer aerogel.

[0042] In the present invention, the mass ratio of the polymer to the natural oil is preferably 1:2-4; the natural oil preferably includes soybean oil and / or palm oil. In the present invention, the swelling temperature is preferably 130-160°C, and the swelling is preferably performed under stirring. The swelling time is not particularly limited; it only needs to allow the polymer to fully swell.

[0043] In the present invention, the cooling step is preferably performed by placing the swollen polymer in an ice water bath. Cooling can shape the polymer and form a rich porous structure.

[0044] The present invention has no special limitation on the cleaning, and the natural oils and fats can be washed out.

[0045] In the present invention, the modified material containing the covalent organic framework material preferably further includes a binder and a conductive material.

[0046] In the present invention, the mass ratio of the covalent organic framework material to the conductive material is preferably 1:10 to 50, more preferably 1:15 to 45, and further preferably 1:20 to 30;

[0047] The mass ratio of the conductive material to the adhesive is preferably 1 to 5:1, more preferably 2 to 4:1, and further preferably 2.5 to 3:1; the conductive material preferably includes conductive carbon black; the adhesive preferably includes polytetrafluoroethylene emulsion; and the solid content of the polytetrafluoroethylene emulsion is preferably 60%.

[0048] When the columnar electrode active material further includes a binder and a conductive material, the method for preparing the modified material containing the covalent organic framework material preferably includes the following steps:

[0049] The covalent organic framework material, the binder and the conductive material are mixed, heated and rolled to obtain the modified material containing the covalent organic framework material.

[0050] In the present invention, the covalent organic framework material preferably includes a melamine / terephthalaldehyde covalent organic framework material.

[0051] The preparation method of the melamine / terephthalaldehyde covalent organic framework material preferably comprises the following steps:

[0052] Melamine, terephthalaldehyde and a polar organic solvent are mixed and subjected to a solvothermal reaction to obtain the melamine / terephthalaldehyde covalent organic framework material.

[0053] In the present invention, the mixing preferably includes: dissolving melamine in a polar organic solvent and then mixing with terephthalaldehyde.

[0054] In the present invention, the molar ratio of melamine to terephthalaldehyde is preferably 1:1-3, more preferably 1:1.5-2.

[0055] In the present invention, the temperature of the solvothermal reaction is preferably 160-210° C., more preferably 180-200° C.; the time is preferably 8-72 h, more preferably 20-50 h, further preferably 30-40 h.

[0056] After the solvothermal reaction, the present invention preferably filters the obtained solvothermal reaction product, and washes and dries the obtained solid to obtain the melamine / terephthalaldehyde covalent organic framework material.

[0057] In the present invention, the columnar electrode active material is preferably fixed by a fastening clamp. In the present invention, the housing further comprises an air inlet.

[0058] The present invention also provides an electro-Fenton system, comprising a power supply, an anode, a cathode and a reaction cell;

[0059] The cathode is the cathode of the electric Fenton system described in the above scheme, and the electrode sheet containing a through hole in the cathode of the electric Fenton system is connected to the negative electrode of the power supply through a wire;

[0060] The reaction tank comprises a water inlet, a water outlet and an air inlet;

[0061] In terms of spatial orientation, the anode is below the water outlet;

[0062] The cathode of the electro-Fenton system is connected to the gas inlet.

[0063] In the present invention, the cathode of the electro-Fenton system is preferably connected to the air inlet of the reaction cell through the air inlet of the shell.

[0064] The present invention also provides the application of the electro-Fenton system described in the above solution in degrading organic matter.

[0065] The electro-Fenton system cathode, the electro-Fenton system and applications thereof provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0066] The structural diagram of the cathode of the electro-Fenton system in the embodiment of the present invention and the comparative example is as follows: Figure 1 As shown: 1-fastening clamp, 2-electrochemical reduction reaction zone (columnar electrode active material), 3-annular electrode sheet, 4-columnar polymer aerogel, 5-shell, 6-air inlet.

[0067] The structural diagram of the electro-Fenton system in the embodiment of the present invention and the comparative example is as follows: Figure 2 shown.

[0068] Example 1

[0069] Polypropylene was dissolved in palm oil at a high temperature of 160°C (the ratio of polypropylene to palm oil was 1:2) and completely swelled under stirring. The mixture was then poured into a mold and quenched in an ice-water bath to obtain a columnar polypropylene aerogel with a diameter of 5 cm and a thickness of 1 cm, which served as the air inlet distribution area.

[0070] Melamine is dissolved in dimethyl sulfoxide, heated and stirred until completely dissolved, and then terephthalaldehyde (molar ratio of 1:3) is added. The mixture is stirred and heated at 180°C for 8 hours. The obtained solid is washed and dried to obtain a covalent organic framework material.

[0071] The covalent organic framework material, conductive carbon black and polytetrafluoroethylene emulsion (solid content 60%) were evenly mixed in a ratio of 0.1:1:1, heated and roller-pressed to obtain a columnar electrochemical reduction catalytic reaction electrode with a diameter of 5 cm and a thickness of 0.5 cm.

[0072] Polypropylene aerogel, an annular electrode sheet (outer diameter 5 cm, inner diameter 4.5 cm, thickness 0.5 mm), and an electrochemical reduction catalytic reaction electrode were stacked and placed in a shell with an inner diameter of 5 cm and fixed with a fastening clamp to obtain an electro-Fenton system cathode.

[0073] Assembling an electro-Fenton system by using a platinum electrode as an anode, the electro-Fenton system cathode, a power supply and a reaction cell;

[0074] The reaction tank comprises a water inlet, a water outlet and an air inlet;

[0075] The anode is below the water outlet;

[0076] The cathode of the electro-Fenton system is connected to the air inlet;

[0077] The annular electrode sheet in the cathode of the electro-Fenton system is connected to the negative electrode of the power supply through a wire.

[0078] 1% sodium sulfate was added to a 10 mg / L methylene blue solution and passed through the water inlet of the electro-Fenton system. The current of the electro-Fenton system was 40 mA. After 100 minutes of reaction, the degradation rate of methylene blue was 100%. Figure 3 As shown in curve a.

[0079] The stability of the electro-Fenton system cathode prepared in Example 1 in degrading methylene blue by electro-Fenton reaction was determined by cyclic degradation experiments. Figure 4 shown.

[0080] Depend on Figure 4 It can be seen that the cathode of the electro-Fenton system has good stability, and the degradation rate of methylene blue did not decrease significantly after repeated use for three times.

[0081] Example 2

[0082] The only difference from Example 1 is that the molar ratio of melamine to terephthalaldehyde is 1:1.

[0083] Example 3

[0084] The only difference from Example 1 is that the molar ratio of melamine to terephthalaldehyde is 1:2.

[0085] 1% sodium sulfate was added to a 10 mg / L methylene blue solution and introduced into the water inlet of the electro-Fenton system of Examples 1 to 3 respectively. The current of the electro-Fenton system was 40 mA. The degradation experiment of the methylene blue solution was carried out. The results are shown in FIG. Figure 5 shown.

[0086] Depend on Figure 5 It can be seen that when the molar ratio of melamine to terephthalaldehyde is 1:3, the degradation efficiency of methylene blue is the highest, and the degradation rate of methylene blue is 100% after 100 minutes of reaction.

[0087] Example 4

[0088] The only difference from Example 1 is that high-density polyethylene is used to prepare the aerogel and the swelling temperature is 130°C.

[0089] Comparative Example 1

[0090] The only difference from Example 1 is that no covalent organic framework material is added.

[0091] That is, the difference between Comparative Example 1 and Example 1 is that the electrochemical reduction reaction zone in the electrode is not loaded with a covalent organic framework, and the degradation rate of methylene blue is 40% after 100 minutes of reaction. Figure 3 As shown in curve b.

[0092] Depend on Figure 3 It can be seen that compared with the use of electrodes without adding covalent organic framework materials, the addition of covalent organic framework materials can significantly improve the degradation rate of methylene blue, indicating that covalent organic framework materials can promote the conversion of H2O2 into hydroxyl radicals, thereby improving the degradation rate of organic matter.

[0093] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An electro-Fenton system cathode, characterized in that: include: From bottom to top, the columnar polymer aerogel, the electrode sheet with through holes and the columnar electrode active material embedded in the shell; The electrode sheet containing through holes is in contact with the columnar electrode active material; The pore size of the columnar polymer aerogel is 0.01 to 10 μm; The columnar electrode active material includes a covalent organic framework material or a modified material containing a covalent organic framework material; the covalent organic framework material is a melamine / terephthalaldehyde covalent organic framework material.

2. The electro-Fenton system cathode according to claim 1, characterized in that The electrode sheet containing through holes includes a ring-shaped electrode sheet.

3. The electro-Fenton system cathode according to claim 1, characterized in that The columnar polymer aerogel includes one or more of polypropylene aerogel, polyethylene aerogel, polystyrene aerogel and polyvinyl chloride aerogel.

4. The electro-Fenton system cathode according to claim 1, characterized in that The preparation method of the melamine / terephthalaldehyde covalent organic framework material comprises the following steps: Melamine, terephthalaldehyde and a polar organic solvent are mixed and subjected to a solvothermal reaction to obtain the melamine / terephthalaldehyde covalent organic framework material.

5. The electro-Fenton system cathode according to claim 4, characterized in that The molar ratio of melamine to terephthalaldehyde is 1:1-3.

6. The electro-Fenton system cathode according to claim 4 or 5, characterized in that The temperature of the solvent thermal reaction is 160-210° C., and the time is 8-72 hours.

7. The electro-Fenton system cathode according to claim 1, characterized in that The columnar electrode active material is fixed by a fastening clamp.

8. An electro-Fenton system comprising a power supply, an anode, a cathode and a reaction cell; characterized in that: The cathode is the electro-Fenton system cathode according to any one of claims 1 to 7, wherein the electrode sheet containing a through hole in the electro-Fenton system cathode is connected to the negative electrode of the power supply via a wire; The reaction tank comprises a water inlet, a water outlet and an air inlet; In terms of spatial orientation, the anode is below the water outlet; The cathode of the electro-Fenton system is connected to the gas inlet.

9. Use of the electro-Fenton system according to claim 8 in degrading organic matter.

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