Novel Fe / Co-NPC self-supporting electrode and preparation method and application thereof

Abstract

The invention discloses a novel Fe / Co-NPC self-supporting electrode and a preparation method and application thereof. The preparation method comprises the following steps: S1, preparing Fe / Co-MOF; s2, grinding sucrose, carbon black and Fe / Co-MOF in a mass ratio of (100-10): (200-20): 1 and melamine-formaldehyde resin in an unsolidified state, wherein the use amount of the melamine-formaldehyde resin is 1-1.5 mL / g (sucrose + carbon black); s3, performing compression molding on the substance ground in the step S2 to obtain a molded part; and S4, the formed part is carbonized at the temperature of 600-1000 DEG C. The novel Fe / Co-NPC self-supporting electrode has a large specific surface area, abundant mesopores and good oxygen reduction reaction (ORR) activity, the hardness is 35.8-37.7 HV < 1 >, and the loss rate of Fe and Co after continuous electrolysis is conducted for 24 h is 0.17%-0.2%. The novel Fe / Co-NPC self-supporting electrode is not prone to falling off, loss of the Fe / Co-MOF material is reduced, the Fe / Co-MOF material in the electrode also has high catalytic activity, high mechanical strength and high stability, and the novel Fe / Co-NPC self-supporting electrode is suitable for a heterogeneous electro-Fenton system and can efficiently, stably, continuously and repeatedly degrade macromolecular organic pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of water pollution control, and more particularly to a novel Fe / Co-NPC self-supporting electrode and its preparation method and application. Background Art

[0002] Macromolecular organic pollutants have complex molecular structures (such as cationic xanthene dyes rhodamine B - RhB, polychlorinated biphenyls PCBs, dioxins, etc.), and they degrade slowly in the natural environment and can remain in soil, sediment, and water bodies for a long time.

[0003] Traditional treatment methods such as physical methods (precipitation, adsorption) and biological methods (anaerobic digestion, activated sludge method, biological filter) have poor treatment effects on macromolecular organic pollutants. Chemical advanced oxidation processes can be used for deep degradation, such as the heterogeneous electro-Fenton (HEF) system. In the HEF system, the oxygen reduction reaction occurs through electrode catalysis to generate H2O2, and H2O2 undergoes the Fenton reaction with ferrous in the system to effectively degrade refractory organic pollutants. Research shows that the H2O2 production capacity and Fenton catalytic performance in the HEF system are restricted by the type and structure of the catalyst. Currently, common doping of metal (or non-metal) elements is used to regulate the electronic structure of the HEF catalyst, thereby improving the performance of the HEF system catalyst. However, a large amount of catalyst components are easily detached from the electrode surface and are not easily recovered. This not only makes it difficult to guarantee the effect of degrading organic matter but also causes secondary pollution.

[0004] Therefore, there is currently a lack of an HEF system electrode that can stably and efficiently degrade macromolecular organic pollutants. Summary of the Invention

[0005] In view of the above disadvantages of the prior art, the purpose of this application is to provide an HEF system electrode that can stably and efficiently degrade macromolecular organic pollutants and its preparation method and application.

[0006] More specifically, in the first aspect, this application provides a preparation method for a novel Fe / Co-NPC self-supporting electrode, including the following steps:

[0007] S1. Prepare Fe / Co-MOF;

[0008] S2. Grind sucrose, carbon black, and the Fe / Co-MOF in a mass ratio of 100 - 10:200 - 20:1 and the unfrozen melamine-formaldehyde resin, and the usage amount of the melamine-formaldehyde resin is 1 - 1.5 mL / g (sucrose + carbon black);

[0009] S3. Press the ground material in step S2 into a formed part;

[0010] S4. Carbonize the formed part at 600°C - 1000°C.

[0011] Preferably, step S1 includes: FeCl3·6H2O, Co(NO3)2·6H2O and terephthalic acid are subjected to a hydrothermal reaction at a molar ratio of 1 - 3:1 - 5:1 - 3 at 100 - 120°C to prepare Fe / Co-MOF.

[0012] Preferably, step S1 includes: FeCl3·6H2O, Co(NO3)2·6H2O and terephthalic acid react at a molar ratio of 3:1:2 at 110°C for 24 h to prepare Fe / Co-MOF.

[0013] Preferably, the quantitative relationship between the formaldehyde solution and melamine used in the preparation of melamine-formaldehyde resin is: 3 - 12 g of melamine is added to every 10 mL of formaldehyde.

[0014] Preferably, the quantitative relationship between the formaldehyde solution and melamine used is: 6.3 g of melamine is added to every 10 mL of 38% formaldehyde solution.

[0015] Preferably, step S2 includes: grinding sucrose, carbon black and Fe / Co-MOF with a mass ratio of 100:200:1 and the unfixed melamine-formaldehyde resin, and the usage amount of the melamine-formaldehyde resin is 1 - 1.5 mL / g (sucrose + carbon black).

[0016] In a second aspect, the present application provides a novel Fe / Co-NPC self-supporting electrode, and the novel Fe / Co-NPC self-supporting electrode is prepared by the preparation method of the novel Fe / Co-NPC self-supporting electrode described above.

[0017] Preferably, the novel Fe / Co-NPC self-supporting electrode is in a block shape, and / or the hardness of the novel Fe / Co-NPC self-supporting electrode is 35.8 - 37.7 HV 1.

[0018] Preferably, the loss rates of Fe and Co after the novel Fe / Co-NPC self-supporting electrode is continuously electrolyzed for 24 h are between 0.17% and 0.2%.

[0019] In a third aspect, the present application provides a heterogeneous electro-Fenton reaction system, and the heterogeneous electro-Fenton reaction system uses the novel Fe / Co-NPC self-supporting electrode described above as the cathode.

[0020] In a fourth aspect, the present application provides an application of the novel Fe / Co-NPC self-supporting electrode or the heterogeneous electro-Fenton reaction system described above in degrading macromolecular organic pollutants.

[0021] Preferably, the macromolecular organic pollutant is RhB.

[0022] The technical solution of this application achieves the following technical effects:

[0023] 1. The novel Fe / Co-NPC self-supporting electrode of this application is applicable to the heterogeneous electro-Fenton (HEF) system. It can not only degrade macromolecular organic pollutants (such as RhB) efficiently and stably, but also be recycled for sustainable multiple uses.

[0024] 2. For the novel Fe / Co-NPC self-supporting electrode of this application, due to the addition of sucrose and carbon black, after high-temperature carbonization, its pore structure is affected by the pyrolysis process, volatilization release, and carbon skeleton reorganization, generating a large number of micropores and mesopores. On the one hand, the Fe / Co-NPC self-supporting electrode has a large specific surface area, and the Fe / Co-MOF doping is more uniform; on the other hand, it provides rich active sites and gas transmission channels, improving the oxygen reduction reaction (ORR) activity; on the other hand, it enhances the conductivity of the self-supporting electrode, reduces the charge transfer resistance, and is more conducive to electron transfer.

[0025] 3. For the novel Fe / Co-NPC self-supporting electrode of this application, due to the addition of melamine-formaldehyde resin, N element is introduced, changing the internal electron density distribution, optimizing the O2 reduction path, and effectively improving the oxygen reduction reaction (ORR) activity; at the same time, the N-C bond structure enhances the chemical stability of the electrode compared with the C-C bond.

[0026] 4. Compared with the existing powdered Fe / Co-MOF material that is applied to the electrode after carbonization (which is easy to fall off), the novel Fe / Co-NPC self-supporting electrode of this application is a formed part (such as a block). On the one hand, it is not easy to fall off, reducing the loss of the Fe / Co-MOF material (the loss rate of Fe and Co is 0.17% - 0.2% after continuous electrolysis for 24h); on the other hand, the Fe / Co-MOF material inside the electrode also has strong catalytic activity and is not easy to deactivate; on the other hand, it has a certain hardness (35.8 - 37.7HV 1), high mechanical strength, and strong stability, which can greatly increase the number of recycling times.

[0027] 5. The novel Fe / Co-NPC self-supporting electrode of this application has less leaching of Fe and Co, good stability, is easy to recycle, and the recycled electrode still has a high degradation rate for macromolecular organic pollutants.

[0028] The following will further illustrate the concept, specific structure, and technical effects generated by this application in conjunction with the drawings to fully understand the purpose, features, and effects of this application. Description of the Drawings

[0029] Figure 1 It is a finished product diagram of the novel Fe / Co-NPC self-supporting electrode of this application.

[0030] Figure 2 It is a scanning electron microscope image of the novel Fe / Co-NPC self-supporting electrode of this application.

[0031] Figure 3 It is an elemental mapping diagram of the novel Fe / Co-NPC self-supporting electrode of this application.

[0032] Figure 4 It is an XRD spectrum diagram of the novel Fe / Co-NPC self-supporting electrode of this application.

[0033] Figure 5 It is an FTIR spectrum diagram of the novel Fe / Co-NPC self-supporting electrode of this application.

[0034] Figure 6 It is a nitrogen adsorption-desorption isotherm curve diagram of the novel Fe / Co-NPC self-supporting electrode of this application.

[0035] Figure 7 It is a pore size distribution diagram of the novel Fe / Co-NPC self-supporting electrode of this application.

[0036] Figure 8 It is an XPS spectrum diagram of the novel Fe / Co-NPC self-supporting electrode of this application.

[0037] Figure 9 It is a CV curve diagram comparing the novel Fe / Co-NPC self-supporting electrode of this application and the NPC electrode of undoped Fe / Co-MOF.

[0038] Figure 10 It shows the Vickers hardness of Fe / Co-NPC before carbonization, about 40HV 1.

[0039] Figure 11 It shows the Vickers hardness of Fe / Co-NPC after carbonization, between 35.8 - 37.7HV 1.

[0040] Figure 12 It is a schematic diagram of the heterogeneous electro-Fenton reaction system of this application.

[0041] Figure 13 It is the degradation effect diagram of RhB wastewater by the heterogeneous electro-Fenton reaction system of this application when the initial applied current is 0, 25, 50, 100, 150 mA respectively.

[0042] Figure 14 It is the degradation effect diagram of the heterogeneous electro-Fenton reaction system of this application after multiple cycles.

[0043] Figure 15This is a graph showing the change in the degradation rate K of the heterogeneous electro-Fenton reaction system of this application after multiple cycles.

[0044] Figure 16 This is a graph showing the change in the leaching amounts of Fe and Co metal ions in the heterogeneous electro-Fenton reaction system of this application after multiple cycles.

[0045] Figure 17 This is an effect diagram showing the degradation of RhB wastewater with different concentrations by the heterogeneous electro-Fenton reaction system of this application. Detailed implementation modes

[0046] The following specific examples illustrate the implementation modes of this application. Those skilled in the art can easily understand the other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific implementation modes. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0047] For the purpose of illustration, some exemplary embodiments of this application are described. It should be understood that this application can be implemented in other ways not specifically shown in the drawings.

[0048] "NPC" is fully called Nitrogen-Doped Porous Carbon, that is, nitrogen-doped porous carbon material. <![CDATA[ ]]><![CDATA[

[0049] ]]>In the first aspect, this application discloses a preparation method of a novel Fe / Co-NPC self-supporting electrode. It hydrothermally synthesizes a precursor doped with Fe / Co (Fe / Co-MOF), and then mixes and presses sucrose, carbon black, and melamine-formaldehyde resin and carbonizes them to make the Fe / Co-NPC self-supporting electrode. A series of pyrolysis, carbonization, metal reduction, and nitrogen doping reactions occur in the raw materials of this synthesis method, and finally a composite material of highly conductive N-doped porous carbon loaded with Fe / Co nanoparticles is formed. <![CDATA[ ]]><![CDATA[

[0050] ]]>The above synthesis method generally includes the following steps: S1, prepare Fe / Co-MOF; S2, grind a certain proportion of sucrose, carbon black, and Fe / Co-MOF and the unfrozen melamine-formaldehyde resin; S3, press the ground material in step S2 into a molded part; S4, carbonize the molded part obtained in step S3. The following details each step. <![CDATA[ ]]><![CDATA[

[0051] ]]>1. Regarding the preparation of Fe / Co-MOF <![CDATA[ ]]><![CDATA[

[0052] ]]>Add the raw materials FeCl3·6H2O, Co(NO3)2·6H2O, terephthalic acid and the solvent N,N-dimethylformamide (DMF) into the reactor. After stirring at room temperature until completely dissolved, transfer it to a high-pressure reactor for hydrothermal reaction. Among them, the molar ratio of FeCl3·6H2O, Co(NO3)2·6H2O and terephthalic acid is 1-3:1-5:1-3. For example, it can be 3:1:2, 1:1:1, 1:5:3. It should be understood that the several listed ratios do not constitute a limitation of this application. Those skilled in the art can select within the range of 1-3:1-5:1-3 or adjust according to the actual situation. The hydrothermal reaction conditions are to react at a temperature of 100-120 °C for 22-26 h. For example, it can react at a temperature of 110 °C for 24 h, or react at a temperature of 120 °C for 22 h, etc.

[0053] After the hydrothermal reaction is completed, let the reactor cool naturally and then centrifuge to obtain a brown solid. Then, use DMF and ethanol to centrifuge and wash it several times in sequence, and place it in a vacuum drying oven for vacuum drying to obtain a pale yellow powder, that is, the Fe / Co-doped metal-organic framework compound (Fe / Co-MOF). The purpose of placing it in the vacuum drying oven for drying is to remove the solvents (such as water, alcohols, etc.) and residual other impurities in it, while maintaining the structural integrity of the material to ensure the performance stability of Fe / Co-MOF. For example, it can be vacuum dried at 60 °C in the vacuum drying oven for 12 h. Those skilled in the art can make corresponding adjustments to the drying temperature and drying time as long as the aforementioned purpose is achieved.

[0054] 2. Regarding the preparation of melamine-formaldehyde resin

[0055] In this application, the melamine-formaldehyde resin can be prepared by itself or directly purchased from the market. Preferably, the nitrogen content of the melamine-formaldehyde resin is 30 wt% - 48 wt%. The following introduces the self-preparation method of the melamine-formaldehyde resin.

[0056] Take 10 mL of formaldehyde solution (concentration 35% - 40%, for example 38%) in a 50 mL beaker, add 0.024 g of hexamine and stir. After complete dissolution, place it on a graphite plate and heat at 100 °C. Then add 3 g - 12 g of melamine and keep stirring until the solution is clear. Continue heating for 10 min to obtain the melamine-formaldehyde resin.

[0057] It should be understood that those skilled in the art can adjust the reaction time, reaction temperature and the dosage of materials accordingly according to the above method. When it is necessary to prepare a relatively large amount of melamine-formaldehyde resin, the above raw materials can be increased in the same proportion.

[0058] 3. Regarding the novel Fe / Co-NPC self-supporting electrode

[0059] Put sucrose, carbon black, and the prepared Fe / Co-MOF into a grinding jar, and add melamine-formaldehyde resin in an uncured state (which can be commercially available or prepared by oneself through the above method). Place the grinding jar in a grinder, take it out after sufficient grinding to obtain a mud-like solid, wait until the hardness is slightly appropriate, then put it into a press for shaping to form a shaped part, and then place it in a vacuum drying oven for drying. Then, perform high-temperature carbonization on the dried shaped part, and finally perform subsequent cleaning and drying steps to obtain the target product, the novel Fe / Co-NPC self-supporting electrode.

[0060] Among them, the mass ratio of sucrose, carbon black, and Fe / Co-MOF is 100 - 10:200 - 20:1. For example, it can be 100:200:1, 20:40:1, 10:20:1. It should be understood that the several listed ratios do not constitute a limitation of this application, and those skilled in the art can select within the range of 100 - 10:200 - 20:1 or adjust according to the actual situation.

[0061] The usage amount of melamine-formaldehyde resin is 1 - 1.5 mL / g (sucrose + carbon black). The usage amount of melamine-formaldehyde resin is related to the total mass of sucrose and carbon black. For example, if the total mass of sucrose and carbon black is 2 g, then the usage amount of melamine-formaldehyde resin is 2 - 3 mL. The reason for choosing the uncured state of melamine-formaldehyde resin is to make the mixing with sucrose, carbon black, and Fe / Co-MOF more uniform and sufficient during the grinding process.

[0062] "Wait until the hardness is slightly appropriate" in "put it into a press for shaping after waiting until the hardness is slightly appropriate" can be understood as slightly cooled. The purpose is for subsequent shaping. It should be understood that the degree of slightly appropriate hardness or slightly cooled can be selected according to the actual situation or the experience of those skilled in the art, as long as subsequent shaping can be achieved.

[0063] The thickness of the shaped part is selected to be greater than 2 mm, preferably 2 - 5 mm. If it is too thin, it is easy to break during subsequent high-temperature carbonization. This application does not require the shape of the shaped part, which can be a regular shape such as a circle, square, polygon, etc., or an irregular shape.

[0064] The purpose of drying the shaped part in a vacuum drying oven is to remove solvents and water (such as the water in the resin or the humidity generated during grinding. The residue of these solvents and water will affect the subsequent structural stability), and it will not collapse due to solvent volatilization or structural instability during subsequent high-temperature heat treatment (such as carbonization). The drying conditions are preferably drying at 210 - 230 °C for 1.5 - 2.5 h to promote the preliminary curing of melamine-formaldehyde resin and improve the mechanical strength of the material.

[0065] High-temperature carbonization can be carried out in a tube furnace. Place the dried formed parts in the tube furnace, and heat them up to 600℃ - 1000℃ at a heating rate of 5 - 8℃ / min in an N2 atmosphere for high-temperature carbonization for 100 - 140 min, and then take them out after natural cooling. The reaction process of high-temperature carbonization is mainly divided into three stages: low-temperature stage, medium-temperature stage, and high-temperature stage. Among them, in the low-temperature stage (<300℃): the melamine-formaldehyde resin in the formed parts crosslinks and cures, and part of the sucrose dehydrates, undergoing an early thermal decomposition process to form a preliminary carbonization precursor. In the medium-temperature stage (300 - 600℃), the carbonization of melamine-formaldehyde resin and the degradation process of Fe / Co-MOF ligands mainly occur: the melamine-formaldehyde resin decomposes, releasing NH3, H2O, CO2, and CO to form an N-doped carbon skeleton; the structure of Fe / Co-MOF disintegrates, and the organic ligand (terephthalic acid) decomposes at 350 - 500℃ to obtain Fe and Co ions; sucrose pyrolyzes to form amorphous carbon and nitrogen-doped carbon (N-C), and at this time, Fe and Co ions interact and combine with the resin and sucrose carbide. In the high-temperature stage (range: 600 - 800℃), the carbonization and metal reduction processes mainly occur. The melamine-formaldehyde resin and sucrose are completely carbonized to form a highly conductive N-C structure. Fe / Co ions combine with carbon black and the sucrose carbon skeleton, and part of them is reduced to Fe / Co metal nanoparticles, and part of the Fe / Co still exists in the form of oxides. At the same time, Fe / Co atoms combine with the nitrogen-doped carbon substrate to form a structure of Fe-N4 / Co-N4.

[0066] The addition of sucrose and carbon black affects the pore structure of the formed parts after high-temperature carbonization due to the pyrolysis process, volatilization release, and carbon skeleton reorganization, resulting in a large number of micropores and mesopores. On the one hand, it makes the formed parts have a large specific surface area and more uniform Fe / Co-MOF doping; on the other hand, it provides rich active sites and gas transport channels, improving the oxygen reduction reaction (ORR) activity; on the other hand, it enhances the conductivity of the self-supporting electrode, reduces the charge transfer resistance, and is more conducive to the transfer of electrons.

[0067] The addition of melamine-formaldehyde resin introduces N elements, changes the internal electron density distribution, optimizes the O2 reduction path, and effectively improves the oxygen reduction reaction (ORR) activity; at the same time, the N-C bond structure enhances the chemical stability of the electrode compared to the C-C bond.

[0068] The formed parts taken out after natural cooling after carbonization are soaked in dilute hydrochloric acid, then washed with deionized water multiple times and placed in a vacuum drying oven (50 - 70℃) for constant-temperature drying for 10 - 14 h to finally obtain the Fe / Co-NPC self-supporting electrode.

[0069] In the second aspect, the present application provides a Fe / Co-NPC self-supporting electrode, which is prepared by the above method. Preferably, the new Fe / Co-NPC self-supporting electrode is in block shape, has a hardness of 35.8-37.7HV 1, and the loss rate of Fe and Co after 24 hours of continuous electrolysis is 0.17% to 0.2%. Compared with the existing powdered Fe / Co-MOF material that is carbonized and then applied to the electrode (easy to fall off), the new Fe / Co-NPC self-supporting electrode of the present application is a formed part (for example, a block). On the one hand, it is not easy to fall off, which reduces the loss of Fe / Co-MOF material; on the other hand, the Fe / Co-MOF material inside the electrode also has strong catalytic activity and is not easy to deactivate; on the other hand, it has a certain hardness (35.8-37.7HV 1), high mechanical strength, strong stability, and can greatly increase the number of cycles. The electrode is suitable for heterogeneous electro-Fenton system (as a cathode), which can not only efficiently and stably degrade macromolecular organic pollutants, but also can be recycled and processed to achieve sustainable multiple uses.

[0070] Thirdly, this application provides a heterogeneous electro-Fenton reaction system using the novel Fe / Co-NPC self-supporting electrode prepared by the above method as the cathode and a platinum electrode as the anode. This system can deeply degrade macromolecular organic pollutants. The specific reaction mechanism is as follows:

[0071] O2 is reduced to active oxygen species H2O2 and O2 on the electrode surface - , in Fe 2+ Under the action of H2O2, H2O2 is further converted into ·OH. The larger porosity of Fe / Co-NPC makes it easy for H2O2 to react with metal sites in a Fenton-like reaction. 2+ Oxidized to Fe 3+ , and at the same time generate strong oxidizing ·OH, then, Fe 3+ Co 2+ 、Fe 0 Various particles such as Fe 2+ Re-enter the oxygen reduction process, thus achieving a dynamic cycle of Fe and Co. The main reaction process is shown in formula (1-6). - Oxidation, through multi-step degradation (such as N-deethylation process, chromophore breakage, ring opening, mineralization, etc., it should be understood that the degradation process varies depending on the organic matter), is finally oxidized to simple inorganic substances, such as carbon dioxide, etc., as shown in formula (7).

[0072] O2+e - → O2 - (1)

[0073] O2+2H+ +2e - →H2O2 (2)

[0074] Fe 2+ +H2O2→Fe 3+ +·OH+OH - (3)

[0075] Fe 3+ +CO 2+ →Fe 2+ +Co 3+ (4)

[0076] 2Fe 3+ + Fe 0 →3Fe 2+ (5)

[0077] Fe 3+ / Co 3+ +H2O2→Fe 2+ / Co 2+ +·O2 - +2H + (6)

[0078] Macromolecular organic pollutants + ·OH / ·O2 - → …… →H2O + CO2(7)

[0079] The above heterogeneous electro-Fenton reaction system has the ability to efficiently and stably degrade macromolecular pollutants. Among them, the novel Fe / Co-NPC self-supporting electrode has higher electrical conductivity and ORR catalytic activity, achieving the purpose of deeply degrading macromolecular organic pollutants, and is easy to recycle and reuse.

[0080] Fourthly, this application provides an application of the above novel Fe / Co-NPC self-supporting electrode or the above heterogeneous electro-Fenton reaction system in degrading macromolecular organic pollutants. This application presents the degradation effect of the above novel Fe / Co-NPC self-supporting electrode or the above heterogeneous electro-Fenton reaction system by taking the refractory macromolecular organic pollutant RhB as an example. It should be understood that RhB does not constitute a limitation on the types of macromolecular organic pollutants that can be degraded by this application. Except for RhB, the novel Fe / Co-NPC self-supporting electrode or the above heterogeneous electro-Fenton reaction system of this application can still degrade almost all other macromolecular organic pollutants.

[0081] Example 1 Preparation of the novel Fe / Co-NPC self-supporting electrode I

[0082] 1. Preparation of Fe / Co-MOF

[0083] 4.5 mmol of FeCl3·6H2O, 1.5 mmol of Co(NO3)2·6H2O, and 3.0 mmol of terephthalic acid were added to 35 mL of DMF solution. After complete dissolution by magnetic stirring at room temperature, the solution was transferred to a high-pressure reactor and reacted at 110 °C for 24 h. After natural cooling, brown solids were obtained by centrifugation, and then centrifugally washed several times with DMF and ethanol in sequence, and then placed in a vacuum drying oven at 60 °C for vacuum drying for 12 h. Finally, a yellowish-brown powder, Fe / Co-MOF, was obtained.

[0084] 2. Preparation of melamine-formaldehyde resin

[0085] 10 mL of 38% formaldehyde solution was added to a 50 mL beaker, and 0.024 g of hexamethylenetetramine was added and stirred. After complete dissolution, it was heated on a graphite plate at 100 °C, and 6.3 g of melamine was added while stirring continuously until the solution became clear. After continued heating for 10 min, melamine-formaldehyde resin was obtained.

[0086] 3. Novel Fe / Co-NPC self-supporting electrode

[0087] 1 g of sucrose, 2 g of carbon black, and 100 mg of Fe / Co-MOF were placed in a grinding jar, and 4 mL of the hot melamine-formaldehyde resin prepared above that had not cooled and solidified was added. After sufficient grinding by a grinder, a mud-like solid was taken out. After the hardness was slightly appropriate, it was placed in a press for shaping, pressed into a disc with a diameter of 20 mm and a thickness of 2 mm, and placed in a vacuum drying oven and dried at 220 °C for 2 h. The disc was placed in a tube furnace and heated to 800 °C at a rate of 7 °C / min in a 0.5 L / min N2 atmosphere for high-temperature carbonization for 120 min. After natural cooling, it was taken out, immersed in 0.1 mol / L HCl for 20 min, washed several times with deionized water, and then placed in a vacuum drying oven and dried at 60 °C for 12 h. Finally, a novel Fe / Co-NPC self-supporting electrode was obtained (as Figure 1 shown).

[0088] The morphology of the novel Fe / Co-NPC self-supporting electrode prepared in this example was observed by scanning electron microscopy, and the results are as Figure 2 shown. It can be seen that the surface of the Fe / Co-NPC self-supporting electrode is rough and has well-developed pores.

[0089] Figure 3 The energy spectrum diagram shown as

[0090] Figure 4The X-ray diffractometer (XRD) was used to analyze the crystal phase structure of the Fe / Co-NPC self-supporting electrode. Obvious diffraction peaks appeared at 2θ = 25.5° and 43.5°, indicating that the self-supporting electrode had been partially graphitized and belonged to amorphous carbon.

[0091] Figure 5 The Fourier transform infrared spectrometer (FTIR) was used to analyze the changes in functional groups of the Fe / Co-NPC self-supporting electrode before and after carbonization. Obvious absorption peaks appeared at 1650 and 3440 cm -1 for both the Fe / Co-NPC self-supporting electrode before carbonization and after carbonization at 800 °C. These were respectively generated by the stretching vibrations of C=O and -OH. By comparing the absorption peak intensities before and after carbonization, it was found that the peak intensity at 1650 cm -1 increased after carbonization, indicating a slight increase in the number of C=O. Absorption peaks appeared at 1420 and 1530 cm -1 before carbonization, which were related to the C-N stretching vibration and NH bending vibration. These two absorption peaks disappeared after carbonization.

[0092] Figure 6 and Figure 7 The specific surface area and pore characteristics of the Fe / Co-NPC self-supporting electrode were tested using a fully automatic specific surface area and porosity analyzer (BET). The nitrogen adsorption / desorption curve of the Fe / Co-NPC self-supporting electrode was a type-IV isotherm, and a H4-type hysteresis loop appeared in the middle region; the specific surface area of the Fe / Co-NPC self-supporting electrode was 455.7181 m 2 / g, the average pore diameter was 3.3086 nm, and the average mesopore diameter was 3.7629 nm. Combining with the pore size distribution diagram ( Figure 7 ), it can be concluded that the pore type of Fe / Co-NPC was mainly mesopores and micropores.

[0093] Figure 8 XPS was used to analyze the functional groups and element valence states of the Fe / Co-NPC self-supporting electrode. From the spectrum ( Figure 8 a), it was found that there were five elements, C, N, O, Fe, and Co, in the Fe / Co-NPC self-supporting electrode, which was consistent with the results of SEM characterization analysis. The C1s spectrum ( Figure 8 b) could be divided into five parts: 248.8 eV (C-C / C=C bond), 285.22 eV (C-N bond), 286.43 eV (C-O bond), 288.48 eV (O-C=O bond), and 291.25 eV (π-π* satellite peak). From the O1s spectrum ( Figure 8 c), three forms of oxygen existence could be seen, namely C=O (531.95 eV), C-O (533.32 eV), and Fe-O (529.85 eV). The N 1s spectrum (Figure 8 d), the three peaks at 398.80, 400.50, and 401.40 eV correspond to three nitrogen species, namely pyridine N, pyrrole N, and graphitic N, respectively. Among them, pyrrole N has excellent catalytic selectivity for the two-electron ORR. The Fe 2p spectrum ( Figure 8 e) shows that the peak at 706.95 eV belongs to Fe 0 , and the peaks at 710.45 and 723.25 eV belong to Fe 2+ , and the binding energies of the corresponding peaks of Fe 3+ are 712.68 eV and 725.42 eV. The peaks at 715.57 and 728.25 eV correspond to the satellite peaks of Fe 2+ , and the peaks at 719.56 and 732.38 eV correspond to the satellite peaks of Fe 3+ . In the Co 2p spectrum ( Figure 8 f), the peaks at 779.87 eV and 782.91 eV belong to Co 2+ and Co 3+ of Co 2p3 / 2, respectively, and the peaks at 793.52 eV and 798.34 eV correspond to Co 2+ and Co 3+ of Co 2p1 / 2, respectively. In addition, the binding energies corresponding to the two satellite peaks of Co are 787.13 and 802.36 eV, respectively.

[0094] To investigate the catalytic activity of the Fe / Co-NPC self-supporting electrode, the CV curves of the Fe / Co-NPC self-supporting electrode and the NPC electrode without Fe / Co-MOF doping were compared, and the results are as Figure 9 shown. The CV curve of the NPC electrode basically shows a rectangular background, and almost no oxygen reduction reaction occurs. In contrast, the Fe / Co-NPC self-supporting electrode shows a curve inconsistent with that of the NPC. The reduction peak of the Fe / Co-NPC self-supporting electrode appears between -0.15 V and -0.05 V, indicating that the oxygen reduction reaction occurs on the Fe / Co-NPC self-supporting electrode and has higher catalytic activity, which is more conducive to electron transfer.

[0095] To investigate the hardness and strength of the as-prepared Fe / Co-NPC self-supporting electrode before and after carbonization, the Vickers hardness of the Fe / Co-NPC self-supporting electrode was measured before and after high-temperature carbonization, and three points of the material were evaluated at each stage. Before carbonization, the Vickers hardness of Fe / Co-NPC was about 40 HV1( Figure 10 ), and after carbonization, its Vickers hardness was between 35.8 - 37.7 HV1( Figure 11This is because the carbonization process causes the decomposition and escape of substances in the electrode, the pores to expand, and the specific surface area to increase, resulting in uneven hardness and a slight decrease. However, it still has a certain compressive strength, ensuring its stability and maintaining its integrity under hydraulic impact conditions, which is conducive to recycling.

[0096] Example 2 Preparation of a novel Fe / Co-NPC self-supporting electrode

[0097] 1. Preparation of Fe / Co-MOF

[0098] 1.5 mmol of FeCl3·6H2O, 1.5 mmol of Co(NO3)2·6H2O and 4.5 mmol of terephthalic acid were added to 35 mL of DMF solution, magnetically stirred at room temperature until completely dissolved, and then transferred to a high-pressure reactor and placed at 100°C for reaction for 26 hours. After natural cooling, centrifugation was performed to obtain a brown solid, which was then centrifuged and washed several times with DMF and ethanol respectively, and placed in a vacuum drying oven at 60°C for 12 hours to finally obtain a brown powder Fe / Co-MOF.

[0099] 2. Preparation of melamine-formaldehyde resin

[0100] Add 10 mL of 35% formaldehyde solution to a 50 mL beaker, add 0.024 g of hexamethylenetetramine and stir. After complete dissolution, place it on a graphite plate and heat it at 100°C. At the same time, add 3.0 g of melamine and continue stirring until the solution is clear. Continue heating for 10 minutes to obtain melamine-formaldehyde resin.

[0101] 3. New Fe / Co-NPC self-supporting electrode

[0102] Take 10g sucrose, 20g carbon black and 100mg Fe / Co-MOF in a grinding jar and add 30mL of the uncooled and solidified hot melamine-formaldehyde resin prepared above. After being fully ground by a grinder, take out the obtained muddy solid, put it into a press to shape it after the hardness is slightly suitable, press it into a round block with a diameter of 20mm and a thickness of 5mm, and put it into a vacuum drying oven and dry it at 210℃ for 2.5h. The round block is placed in a tube furnace and heated to 600℃ for 140min at 6℃ / min under a 0.5L / min N2 atmosphere. Take it out after cooling naturally and put it into 0.1mol / LHCl to soak for 20min. After washing it with deionized water several times, put it into a vacuum drying oven at 50℃ and dry it for 14h. Finally, a new Fe / Co-NPC self-supporting electrode is obtained (the performance parameters of the electrode are similar to those of the electrode obtained in Example 1, which will not be repeated here).

[0103] Example 3 Preparation of a novel Fe / Co-NPC self-supporting electrode

[0104] 1. Preparation of Fe / Co-MOF

[0105] 4.5 mmol of FeCl3·6H2O, 7.5 mmol of Co(NO3)2·6H2O and 4.5 mmol of terephthalic acid were added to a solution containing 35 mL of DMF. After complete dissolution by magnetic stirring at room temperature, the solution was transferred to a high-pressure reactor and reacted at 120 °C for 22 h. After natural cooling, the brown solid was obtained by centrifugation, and then centrifugally washed with DMF and ethanol several times in sequence, and then placed in a vacuum drying oven at 60 °C for vacuum drying for 12 h. Finally, a brownish-yellow powder Fe / Co-MOF was obtained.

[0106] 2. Preparation of melamine-formaldehyde resin

[0107] 10 mL of 40% formaldehyde solution was added to a 50 mL beaker, and 0.024 g of hexamethylenetetramine was added and stirred. After complete dissolution, it was heated on a graphite plate at 100 °C, and at the same time 12.0 g of melamine was added and continuously stirred until the solution became clear. After continuing to heat for 10 min, melamine-formaldehyde resin was obtained.

[0108] 3. Novel Fe / Co-NPC self-supporting electrode

[0109] 1 g of sucrose, 2 g of carbon black and 100 mg of Fe / Co-MOF were taken in a grinding jar, and 4.5 mL of the hot melamine-formaldehyde resin prepared above that had not cooled and solidified was added. After sufficient grinding by a grinder, a muddy solid was taken out. After the hardness was slightly appropriate, it was put into a press for shaping, pressed into a round block with a diameter of 20 mm and a thickness of 3 mm, and placed in a vacuum drying oven for drying at 230 °C for 1.5 h. The round block was placed in a tube furnace and heated to 1000 °C at a rate of 8 °C / min in a 0.5 L / min N2 atmosphere for carbonization for 100 min. After natural cooling, it was taken out, immersed in 0.1 mol / L HCl for 20 min, then washed with deionized water several times and placed in a vacuum drying oven for constant temperature drying at 70 °C for 10 h. Finally, a novel Fe / Co-NPC self-supporting electrode was obtained (the performance parameters of this electrode are similar to those of the electrode prepared in Example 1 and will not be elaborated here).

[0110] Example 4 Preparation of Novel Fe / Co-NPC Self-Supporting Electrode IV

[0111] 1. Preparation of Fe / Co-MOF

[0112] 1.5 mmol of FeCl3·6H2O, 1.5 mmol of Co(NO3)2·6H2O and 1.5 mmol of terephthalic acid were added to a solution containing 35 mL of DMF. After completely dissolving them by magnetic stirring at room temperature, the mixture was transferred to a high-pressure reactor and reacted at 110 °C for 24 h. After natural cooling, the brown solid was obtained by centrifugation, and then centrifugally washed several times with DMF and ethanol in turn, and then placed in a vacuum drying oven at 60 °C for vacuum drying for 12 h. Finally, a yellowish-brown powder Fe / Co-MOF was obtained.

[0113] 2. Preparation of melamine-formaldehyde resin

[0114] 10 mL of 38% formaldehyde solution was added to a 50 mL beaker, and 0.024 g of hexamine was added and stirred. After complete dissolution, it was heated on a graphite plate at 100 °C. At the same time, 6.3 g of melamine was added and continuously stirred until the solution became clear. After continuing to heat for 10 min, melamine-formaldehyde resin was obtained.

[0115] 3. Novel Fe / Co-NPC self-supporting electrode

[0116] 2 g of sucrose, 4 g of carbon black and 100 mg of Fe / Co-MOF were taken in a grinding jar, and 6 mL of the hot melamine-formaldehyde resin prepared above that had not cooled and solidified was added. After being sufficiently ground by a grinder, the mud-like solid was taken out. After the hardness was slightly appropriate, it was put into a press for shaping, pressed into a round block with a diameter of 20 mm and a thickness of 4 mm, and placed in a vacuum drying oven for drying at 220 °C for 2 h. The round block was placed in a tubular furnace and heated to 800 °C at a rate of 7 °C / min in a 0.5 L / min N2 atmosphere for 120 min of high-temperature carbonization. After natural cooling, it was taken out, soaked in 0.1 mol / L HCl for 20 min, washed repeatedly with deionized water, and then placed in a vacuum drying oven for constant-temperature drying at 60 °C for 12 h. Finally, a novel Fe / Co-NPC self-supporting electrode was obtained (the performance parameters of this electrode are similar to those of the electrode prepared in Example 1 and will not be elaborated here).

[0117] Example 5 Preparation of novel Fe / Co-NPC self-supporting electrode Five

[0118] 1. Preparation of Fe / Co-MOF

[0119] 1.5 mmol of FeCl3·6H2O, 7.5 mmol of Co(NO3)2·6H2O and 4.5 mmol of terephthalic acid were added to 35 mL of DMF solution, magnetically stirred at room temperature until completely dissolved, and then transferred to a high-pressure reactor and reacted at 110°C for 24 hours. After natural cooling, centrifugation was performed to obtain a brown solid, which was then centrifuged and washed several times with DMF and ethanol respectively, and placed in a vacuum drying oven at 60°C for 12 hours to finally obtain a brown powder Fe / Co-MOF.

[0120] 2. Preparation of melamine-formaldehyde resin

[0121] Add 10 mL of 38% formaldehyde solution to a 50 mL beaker, add 0.024 g of hexamethylenetetramine and stir. After complete dissolution, place it on a graphite plate and heat at 100°C. At the same time, add 6.3 g of melamine and continue stirring until the solution is clear. Continue heating for 10 minutes to obtain melamine-formaldehyde resin.

[0122] 3. New Fe / Co-NPC self-supporting electrode

[0123] Take 1g sucrose, 2g carbon black and 100mg Fe / Co-MOF in a grinding jar and add 4mL of the uncooled and solidified hot melamine-formaldehyde resin prepared above. After being fully ground by a grinder, take out the obtained muddy solid, put it into a press to shape it after the hardness is slightly suitable, press it into a round block with a diameter of 20mm and a thickness of 2mm, and put it into a vacuum drying oven and dry it at 220℃ for 2h. The round block is placed in a tube furnace and heated to 800℃ for 120min at 7℃ / min under a 0.5L / min N2 atmosphere. Take it out after natural cooling and put it into 0.1mol / L HCl to soak for 20min. After washing with deionized water several times, put it into a vacuum drying oven at 60℃ and dry it for 12h. Finally, a new Fe / Co-NPC self-supporting electrode is obtained (the performance parameters of the electrode are similar to those of the electrode obtained in Example 1, which will not be repeated here).

[0124] Example 6 Construction of a heterogeneous electro-Fenton reaction system

[0125] This embodiment shows a heterogeneous electro-Fenton reaction system constructed using the novel Fe / Co-NPC self-supporting electrode prepared in Example 1 as an example. Specifically, the heterogeneous electro-Fenton reaction system includes a DC power supply, an anode waterproof wire and a cathode waterproof wire, a gas conduit, a gas flow pump, a corundum aeration disk (R=50 mm, thickness=10 mm, aeration volume of 0.2 L / min), a boron glass electrolytic cell (300 mL), a cathode, a novel Fe / Co-NPC self-supporting electrode prepared in Example 1, and an anode platinum sheet electrode (10 mm×10 mm×0.1 mm). The positive electrode of the power supply is connected to the anode waterproof wire, the anode drain wire is connected to the platinum sheet electrode, the negative electrode of the power supply is connected to the cathode waterproof wire, the cathode drain wire is connected to the Fe / Co-NPC self-supporting electrode, and the cathode electrodes are horizontally spaced 2 cm apart. Air passes through the gas flow pump through the air pipe into the corundum aeration disk and is then dispersed into the reaction solution.

[0126] Example 7 Treatment of Macromolecular Organic Pollutants by Heterogeneous Electro-Fenton Reaction System

[0127] In order to verify the treatment effect of the new Fe / Co-NPC self-supporting electrode prepared in this application on macromolecular organic pollutants, this example uses the difficult-to-degrade cationic xanthene dye Rhodamine B (RhB) as an example. RhB has a polyphenyl ring structure, has high chroma at low concentrations, and is pink in color. In natural water bodies, it can produce certain toxic effects on aquatic organisms through light penetration.

[0128] refer to Figure 10 , 100 mL of RhB wastewater solution (initial RhB concentration of 10 mg / L, pH of 5.0, aeration rate of 0.2 L / min) was added to the electrolytic cell of the heterogeneous electro-Fenton reaction system constructed in Example 6, and 0.01 mol of Na2SO4 solution was added. Turn on the DC power supply and adjust the current intensity to 0, 25, 50, 100, and 150 mA respectively. After a reaction time of 35 minutes, the RhB degradation rate was measured. The results are shown in FIG. Figure 11 . It can be seen that at 0 mA, when the reaction reaches 35 minutes, C / C0 is 80%. At this time, the adsorption performance of the Fe / Co-NPC self-supporting electrode plays a dominant role. When the initial current increases from 25 mA to 100 mA, the degradation rate gradually increases and the increase is more obvious. This is because the larger the current, the greater the amount of electron transfer in the same time, the higher the amount of H2O2 generated, and the higher the RhB degradation efficiency. However, when the initial current increases from 100 mA to 150 mA, the degradation rate does not increase significantly. At this time, the main reason limiting the degradation rate is not the H2O2 generation process, but the Fenton reaction process; at the same time, too high a current will enhance the anode hydrogen evolution side reaction, which will inhibit the generation of H2O2 to a certain extent. Considering the degradation efficiency and energy consumption, 100 mA is the optimal initial current condition for this system.

[0129] To investigate the recycling effect of this electrode, six cycles of degradation were carried out under the conditions of an initial current of 100 mA, an initial RhB concentration of 10 mg / L, and an aeration rate of 0.2 L / min. The results are as follows Figure 12 and 13 shown. As can be seen from Figure 12 it, at 5 min, the degradation rate of RhB decreased slightly, and the time required for complete degradation also increased slightly with the increase in the number of cycles. This indicates that there is a certain performance loss during the cycling process of the material. However, the removal rate can approach 100% within 30 minutes. Therefore, the reuse effect of this new type of Fe / Co-NPC self-supporting electrode has not decreased significantly and still has a high degradation rate. As can be seen from Figure 13 it, with the increase in the number of cycles, the degradation rate K gradually decreased because the number of active sites inside the catalyst decreased during the cycling process, resulting in a decrease in the degradation efficiency. However, after 6 cycles, the K value gradually stabilized at about 0.2, indicating that the material exhibits excellent catalytic performance and stability.

[0130] To investigate the stability of this new type of Fe / Co-NPC self-supporting electrode, the changes in the leaching of Fe and Co ions within 24 h of the reaction system were recorded. The results are as follows Figure 14 shown. At 5 min (initial pH = 5.0, initial RhB concentration = 10 mg / L, aeration rate = 0.2 L / min), the leaching amounts of iron ions and cobalt ions were 0.55 and 0.17 mg / L, respectively. The reaction was rapid in the first 5 min of the degradation experiment, and Fe and Co ions were rapidly consumed and partially dissolved into the solution. Thereafter, within 24 h, the leaching amount of iron ions remained at 0.54 - 0.64 mg / L, and the leaching amount of cobalt ions remained at 0.17 - 0.22 mg / L. The leaching amounts of Fe and Co basically remained at a level state. The loss rates of Fe and Co in the Fe / Co-NPC self-supporting electrode were 0.17% - 0.2%, indicating that the material has good stability, Fe / CoMOF is not easily dissolved, and it exhibits excellent catalytic performance and stability.

[0131] In addition, this example also verified the treatment effect of the new type of Fe / Co-NPC self-supporting electrode prepared in this application on macromolecular organic pollutants with different concentrations (taking RhB as an example). Using the heterogeneous electro-Fenton reaction system built in multiple Example 6, 100 mL of RhB wastewater solutions with different concentrations were added to the corresponding electrolytic cells, and 0.01 mol Na2SO4 solution was added. The DC power supply was turned on, and the current intensity was adjusted to 100 mA. The RhB degradation rate was measured as the reaction proceeded. The results are as follows Figure 15As shown. It can be seen that the degradation rate of RhB slows down with the increase of concentration. When the initial concentration C0 of RhB is 10 - 30 mg / L (initial current 100 mA, pH 5.0, aeration rate 0.2 L / min), the reaction time for complete degradation of RhB is 10 - 15 min; when C0 is 50 - 80 mg / L, the complete degradation times increase to 25 and 35 min respectively, indicating that when other system reaction conditions except the initial concentration of RhB are the same, the generation rates of ·OH, ·O2 - etc. are relatively constant. However, with the increase of the initial concentration of RhB, the intermediate products of RhB in the reaction process increase, and there is competition for free radicals between the intermediate products and RhB, resulting in an extension of the corresponding complete degradation time. When the reaction time is 35 min, the degradation rate of RhB reaches 100%. It can be seen that even in a high-concentration RhB solution, the Fe / Co-NPC self-supporting electrode can maintain efficient and stable electro-Fenton catalytic performance.

[0132] The above embodiments are only illustrative of the principles and effects of the present application, and are not used to limit the present application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present application should still be covered by the claims of the present application.

Claims

1. A preparation method of a novel Fe / Co-NPC self-supporting electrode, characterized in that, The following steps are involved: S1, preparation of Fe / Co-MOF; S2. Grinding sucrose, carbon black, the Fe / Co-MOF, and an unsolidified melamine-formaldehyde resin in a mass ratio of 100-10:200-20:1, wherein the amount of the melamine-formaldehyde resin is 1-1.5 mL / g (sucrose + carbon black); S3, pressing the material ground in step S2 into a molded part; S4, carbonizing the molded part at 600°C-1000°C.

2. The preparation method of the novel Fe / Co-NPC self-supporting electrode according to claim 1, wherein, Step S1 includes: FeCl3·6H2O, Co(NO3)2·6H2O and terephthalic acid in a molar ratio of 1-3:1-5:1-3 are subjected to a hydrothermal reaction at 100-120°C to prepare Fe / Co-MOF.

3. The preparation method of the novel Fe / Co-NPC self-supporting electrode according to claim 1, characterized in that, The quantitative relationship between the formaldehyde solution and melamine used in the process of preparing melamine-formaldehyde resin is: 3-12 g of melamine is added to every 10 mL of formaldehyde solution.

4. The preparation method of the novel Fe / Co-NPC self-supporting electrode according to claim 3, wherein, Step S2 includes grinding sucrose, carbon black, Fe / Co-MOF, and unsolidified melamine-formaldehyde resin in a mass ratio of 100:200:1, wherein the amount of the melamine-formaldehyde resin used is 1-1.5 mL / g (sucrose+carbon black).

5. A novel Fe / Co-NPC self-supporting electrode, characterized in that, The novel Fe / Co-NPC self-supporting electrode is prepared by the preparation method of the novel Fe / Co-NPC self-supporting electrode according to any one of claims 1 to 4.

6. The novel Fe / Co-NPC self-supporting electrode according to claim 5, wherein The novel Fe / Co-NPC self-supporting electrode is in block shape, and / or the hardness of the novel Fe / Co-NPC self-supporting electrode is 35.8-37.7 HV 1.

7. The novel Fe / Co-NPC self-supporting electrode according to claim 5, wherein, After continuous electrolysis for 24 hours, the loss rate of Fe and Co in the novel Fe / Co-NPC self-supporting electrode is 0.17% to 0.2%.

8. A heterogeneous electro-Fenton reaction system, characterized in that, The heterogeneous electro-Fenton reaction system uses the novel Fe / Co-NPC self-supporting electrode described in claim 7 as the cathode.

9. Use of the novel Fe / Co-NPC self-supporting electrode according to claim 7 or the heterogeneous electro-Fenton reaction system according to claim 8 in the degradation of macromolecular organic pollutants.

10. The use according to claim 9, wherein the macromolecular organic pollutant is RhB.

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