Preparation method of carbon felt loaded hydroxylated carbon nanotube cathode material, product and application thereof

Abstract

This invention discloses a method for preparing a carbon felt-supported hydroxylated carbon nanotube cathode material, comprising: mixing hydroxylated carbon nanotubes, a binder, and a solvent to obtain a dispersion; immersing a pretreated carbon felt in the dispersion, and drying it after thorough immersion; calcining the dried product, and cooling it to obtain the carbon felt-supported hydroxylated carbon nanotube cathode material. The preparation process disclosed in this invention is simple and controllable, and the raw materials are inexpensive and readily available. Using the material prepared by this method as a cathode, hydrogen peroxide can be produced efficiently, with a maximum accumulation of 638 mg / L after 120 minutes of reaction. Furthermore, using the material prepared by this method as a cathode, aniline and Sb(V) in dyeing and printing wastewater can be completely degraded, meeting the discharge standard GB4287-2012 for dyeing and printing wastewater. Moreover, this cathode material exhibits excellent activity and stability and can be repeatedly recycled.

Description

Technical Field

[0001] This invention relates to the technical field of cathode materials, and in particular to a method for preparing a carbon felt-supported hydroxylated carbon nanotube cathode material, its products, and applications. Background Technology

[0002] The dyeing and printing industry is one of my country's important economic pillars, discharging approximately 1.4 to 1.6 billion tons of dyeing and printing wastewater annually. This wastewater is complex in composition, highly stable, and highly toxic, belonging to the category of high-salt, recalcitrant organic wastewater, posing a significant environmental governance challenge. Aniline and Sb(V) in dyeing and printing wastewater pose a substantial threat to human and animal health even at extremely low concentrations, making the remediation of aniline and Sb(V) pollution an urgent matter.

[0003] Electro-Fenton and electrocoagulation technologies, as environmentally friendly water treatment technologies, have attracted increasing attention for treating recalcitrant organic pollutants and difficult-to-remove heavy metals. However, both still have some problems in practical applications. For example, electro-Fenton technology has low H2O2 utilization, while electrocoagulation technology suffers from drawbacks such as easy electrode passivation and high energy consumption. Developing an electro-Fenton-electrocoagulation synergistic removal technology holds promise for replacing traditional Fenton and electrocoagulation processes, reducing wastewater treatment energy consumption and improving water reuse rates.

[0004] H2O2, as a multifunctional, powerful, and environmentally friendly oxidant, is experiencing rapid demand growth across numerous industries. However, its instability and strong oxidizing properties pose serious safety hazards during transportation. Therefore, the in-situ generation of H2O2 using electrochemical technology and its application in Fe... 2+ The generation of ·OH under the catalysis of H2O2, and the subsequent removal of recalcitrant compounds, has gradually become a hot research topic. The selection of cathode materials is a key factor affecting the in-situ generation of H2O2.

[0005] Carbon felt, as a cathode material in the electro-Fenton-electro-flocculation coupling system, has the characteristics of high stability, large specific surface area, no change in its physical properties after sintering, and the ability to form active sites after activation.

[0006] In the prior art, such as Chinese patent document application number 201711019400.7, a method for preparing and applying an electro-Fenton cathode material based on supported activated carbon fiber is disclosed. This method involves impregnating pretreated activated carbon fibers in a complexing agent and metal salt solution, and using oxygen generated from anodic electrolysis of water to produce H2O2 in situ. This technical solution claims to effectively catalyze the decomposition of hydrogen peroxide to generate hydroxyl radicals. However, it is well known in the art that hydroxyl radicals originate from the decomposition of hydrogen peroxide. When the hydrogen peroxide content is low, even with efficient catalytic decomposition, the amount of hydroxyl radicals produced is limited. Furthermore, based on the concentration of oxides generated in Example 1, the hydrogen peroxide yield after 120 minutes of reaction is only 182.7 μM (6.2 mg / L), indicating a low yield. Therefore, its ability to oxidize and degrade organic pollutants is also limited.

[0007] For example, Chinese patent document application number 202010088753.8 discloses a method for preparing an electro-Fenton cathode material based on cobalt nanoparticles loaded on carbon felt and its application in wastewater treatment. The method involves pretreating the carbon felt material and then firing it in a tube furnace. After cleaning and drying, the carbon felt material is soaked in a methanol solution of cobalt nitrate and polyvinylpyrrolidone. A methanol solution of dimethylimidazole is then added to the original soaking solution, and the carbon felt material is soaked further, depositing a layer of cobalt-dimethylimidazole metal-organic framework compound on the surface of the carbon felt material. Finally, it is fired in a tube furnace to obtain the electro-Fenton cathode material with cobalt nanoparticles loaded on carbon felt. This preparation process is complex, time-consuming, and the introduction of cobalt particles can easily cause secondary pollution.

[0008] Therefore, developing a new type of green and efficient electro-Fenton-electro-coagulation cathode material is of great practical significance. Summary of the Invention

[0009] To address the aforementioned problems in the existing technology, this invention discloses a method for preparing a carbon felt-supported hydroxylated carbon nanotube cathode material. The raw materials are inexpensive and readily available, and the preparation process is simple and controllable. Using the material prepared by this method as a cathode, hydrogen peroxide can be produced efficiently, with the accumulation of hydrogen peroxide reaching up to 638 mg / L after 120 minutes of reaction. Furthermore, using the material prepared by this method as a cathode, aniline and Sb(V) in dyeing and printing wastewater can be completely degraded, meeting the discharge standard GB4287-2012 for dyeing and printing wastewater. Moreover, this cathode material has excellent activity and stability and can be repeatedly recycled.

[0010] The specific technical solution is as follows:

[0011] A method for preparing a carbon felt-supported hydroxylated carbon nanotube cathode material includes the following steps:

[0012] Step 1: Mix hydroxylated carbon nanotubes, binder, and solvent to obtain a dispersion;

[0013] Step 2: Immerse the pretreated carbon felt in the dispersion prepared in Step 1, and dry it after thorough immersion.

[0014] Step 3: The product after drying in step 2 is calcined and cooled to obtain the carbon felt-supported hydroxylated carbon nanotube cathode material.

[0015] This invention discloses a method for preparing a carbon felt-supported hydroxylated carbon nanotube cathode material. Using a dispersion of hydroxylated carbon nanotubes and a binder as raw material, the modified cathode material is prepared by modifying and calcining the carbon felt. Experiments have shown that the cathode material prepared by this special modification method, when used as an electrode, can produce hydrogen peroxide in high yield.

[0016] In step 1:

[0017] Preferably, the adhesive is selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride, and polyvinylidene fluoride; more preferably, it is a commercially available polytetrafluoroethylene emulsion.

[0018] Preferably, the solvent is selected from a mixed solution of water and alcohol, with a volume ratio of water to alcohol of 10:0.5 to 2; more preferably, the volume ratio is 10:1.

[0019] Preferably, the alcohol is selected from one or more of methanol, ethanol, and isopropanol, and more preferably isopropanol.

[0020] In step 1:

[0021] Preferably, the mass ratio of hydroxylated carbon nanotubes to binder is 1:0.5-7; and the mass ratio of hydroxylated carbon nanotubes in the dispersion is 0.01-0.5 g / mL.

[0022] In step 2:

[0023] Preferably, the pretreatment of the carbon felt includes washing and drying;

[0024] Preferably, the mass ratio of the hydroxylated carbon nanotubes added in step 1 to the area of ​​the carbon felt is 3–22 mg / cm². 2 ;

[0025] In step 3:

[0026] Preferably, the calcination temperature is 200–450°C.

[0027] This invention discloses a carbon felt-supported hydroxylated carbon nanotube cathode material prepared according to the above method.

[0028] This invention also discloses a method for in-situ preparation of hydrogen peroxide, using water as the electrolyte, an aluminum plate as the anode, and the aforementioned carbon felt-supported hydroxylated carbon nanotube cathode material as the cathode; the preparation process of the carbon felt-supported hydroxylated carbon nanotube cathode material includes:

[0029] The mass ratio of hydroxylated carbon nanotubes to binder is 1:1 to 5;

[0030] The calcination temperature is 280–360℃;

[0031] The electrolyte has a pH value of 3 to 5.

[0032] Experiments have shown that cathode materials prepared using the further refined process described above can produce a higher yield of hydrogen peroxide.

[0033] Better:

[0034] The mass ratio of hydroxylated carbon nanotubes to binder is 1:1 to 3;

[0035] The mass-to-area ratio of hydroxylated carbon nanotubes to carbon felt is 14–22 mg / cm². 2 ;

[0036] The calcination temperature is 360℃;

[0037] The electrolyte has a pH value of 3 to 4.

[0038] Optimal choice:

[0039] The mass ratio of hydroxylated carbon nanotubes to binder is 1:1;

[0040] The mass ratio of hydroxylated carbon nanotubes to the area of ​​the carbon felt was 14.29 mg / cm². 2 ;

[0041] The electrolyte has a pH value of 3.

[0042] Experiments have shown that the yield of hydrogen peroxide increases with the cathode material prepared using the further defined process described above.

[0043] This invention also discloses a method for treating aniline and Sb(V) in dyeing and printing wastewater using an electro-Fenton-electrocoagulation process, with an iron plate as the anode and the aforementioned carbon felt-supported hydroxylated carbon nanotube cathode material as the cathode; the preparation process of the carbon felt-supported hydroxylated carbon nanotube cathode material includes:

[0044] The mass ratio of hydroxylated carbon nanotubes to binder is 1:1;

[0045] The mass ratio of hydroxylated carbon nanotubes to the area of ​​the carbon felt was 14.29 mg / cm². 2 ;

[0046] The calcination temperature is 360℃.

[0047] Experiments have shown that when the cathode material prepared under the above-mentioned specific process conditions is used as an electrode, it can completely degrade aniline and Sb(V) in dyeing and printing wastewater, meeting the discharge standard GB4287-2012 for dyeing and printing wastewater. Furthermore, the cathode material has excellent activity and stability and can be repeatedly recycled.

[0048] Further experiments revealed that replacing the hydroxylated carbon nanotubes in the preparation process of carbon felt-supported hydroxylated carbon nanotube cathode materials with carbon nanotubes without functional groups or with carboxyl functional groups could not achieve complete degradation of aniline and Sb(V) in dyeing and printing wastewater.

[0049] Preferred:

[0050] The pH value of the dyeing and printing wastewater is 3.0;

[0051] The concentration of electrolyte in the dyeing and printing wastewater is 0.15 mol / L;

[0052] The current used in the electro-Fenton-electrocoagulation process is 0.2–0.25 A.

[0053] Compared with the prior art, the present invention has the following advantages:

[0054] (1) The present invention uses a modified carbon felt cathode material prepared by a special modification process as an electrode to generate H2O2 in situ. By adjusting the loading amount of hydroxylated carbon nanotubes, the mass ratio of hydroxylated carbon nanotubes to binder and the calcination temperature in the modification process, high yield can be achieved, with the highest yield reaching 638 mg / L.

[0055] (2) The present invention uses a modified carbon felt cathode material prepared by a special modification process as the electrode and an iron plate as the anode. By adjusting the loading of hydroxylated carbon nanotubes, the mass ratio of hydroxylated carbon nanotubes to binder and the calcination temperature in the modification process, the electro-Fenton-electro-coagulation combined process is used to achieve complete degradation of aniline and Sb(V) in dyeing and printing wastewater without the need for external flocculants, thus meeting the discharge standard GB4287-2012 for dyeing and printing wastewater.

[0056] (3) The modified carbon felt cathode material prepared by the present invention has high activity and stability. The electrode material can be repeatedly recycled. After being recycled 4 times, the effluent of the dyeing and printing wastewater still meets the discharge standard GB4287-2012 for dyeing and printing wastewater. After being recycled 5 times, the removal rate of aniline in the wastewater can still reach more than 95%. Attached Figure Description

[0057] Figure 1 The image above shows the SEM image of the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in Example 1, and the image below shows the SEM image of the carbon felt that has only undergone pretreatment (for comparison).

[0058] Figure 2 The water contact angle of the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in Example 1 is shown in the upper figure, and the water contact angle of the carbon felt that has only undergone pretreatment is shown in the lower figure for comparison.

[0059] Figure 3 The image shows the cyclic degradation effect of the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in Example 1 as the cathode in the electro-Fenton-electro-coagulation test.

[0060] Figure 4 The graph shows the degradation effect of aniline and Sb(V) in wastewater under different pH conditions when the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in Example 1 is used as the cathode in the electro-Fenton-electrocoagulation experiment.

[0061] Figure 5 The graph shows the degradation effect of aniline and Sb(V) in wastewater under different current conditions when the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in Example 1 is used as the cathode in the electro-Fenton-electrocoagulation experiment.

[0062] Figure 6 The graph shows the degradation effect of aniline and Sb(V) in wastewater under different electrolyte concentrations when the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in Example 1 is used as the cathode in an electro-Fenton-electrocoagulation experiment. Detailed Implementation

[0063] The following description, in conjunction with embodiments, further illustrates the solution of the present invention. It should be noted that the specific implementation methods described herein are merely for illustration and explanation of the present invention and are not intended to limit the scope of protection of the present invention.

[0064] Example 1

[0065] (1) Deposit carbon felt (7cm×5cm×0.2mm, with a deposition area of ​​70cm²) 2 Immerse in ethanol solution and ultrasonically clean for 30 minutes. Repeat the above cleaning process twice, then ultrasonically clean with ultrapure water multiple times, and finally place in a vacuum drying oven to dry.

[0066] (2) Weigh 1g of hydroxylated carbon nanotubes and 1g of polytetrafluoroethylene emulsion, add them to a mixed solution containing 10mL of ultrapure water and 1mL of isopropanol, and sonicate for 30min to obtain a uniform dispersion of hydroxylated carbon nanotubes.

[0067] (3) The carbon felt obtained in step (1) is immersed in the hydroxylated carbon nanotube dispersion obtained in step (2), and the excess dispersion is evenly coated onto the surface of the carbon felt and dried.

[0068] (4) The dried product obtained in step (3) was placed in a muffle furnace and calcined at 360°C for 1 hour. After cooling to room temperature, carbon felt-supported hydroxylated carbon nanotube cathode material was obtained.

[0069] Figure 1 The image above shows the SEM image of the carbon felt cathode material loaded with hydroxylated carbon nanotubes prepared in this embodiment, and the image below shows the SEM image of the carbon felt after only pretreatment. The comparison shows that after the preparation process of this invention, the carbon felt surface has been loaded with hydroxylated carbon nanotubes.

[0070] Figure 2 The water contact angle of the carbon felt loaded with hydroxylated carbon nanotube cathode material prepared in this embodiment is shown in the upper figure, and the water contact angle of the carbon felt after only pretreatment is shown in the lower figure for comparison. The comparison shows that the water contact angle of the carbon felt is improved after the preparation process of the present invention.

[0071] H2O2 cumulative amount test:

[0072] Using an aluminum plate as the anode and the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in this embodiment as the cathode, water was used as the electrolyte, hydrochloric acid was added to adjust the pH to 3.0, NaCl was added to make its concentration 0.15 mol / L, oxygen was continuously introduced near the cathode, and the H2O2 production was tested under the condition of I = 0.2 A.

[0073] Tests showed that after 120 minutes of reaction, the cumulative amount of H2O2 reached 638.8 mg / L.

[0074] Using the same test conditions as described above, only the pH of the electrolyte was adjusted to 2, 4, 5, and 6 in sequence, and the cumulative amount of H2O2 was tested within 120 min. The data are shown in Table 1.

[0075] Table 1

[0076]

[0077] Application performance testing:

[0078] Using an iron plate as the anode and the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in this embodiment as the cathode, wastewater containing 50 mg / L aniline and 5 mg / L Sb(V) was added. Hydrochloric acid was added to adjust the pH of the wastewater to 3.0, and NaCl was added to make its concentration 0.15 mol / L. Oxygen was continuously introduced near the cathode, and an electro-Fenton-electrocoagulation experiment was carried out under the condition of I = 0.2 A.

[0079] After 120 minutes of electro-Fenton-electrocoagulation treatment, the removal rates of aniline and Sb(V) both reached 100%, meeting the discharge standards for dyeing and printing wastewater (GB4287-2012).

[0080] Figure 3 The graph shows the cyclic degradation efficiency of aniline in dyeing and printing wastewater using the carbon felt-supported hydroxylated carbon nanotube cathode material prepared in this embodiment as the cathode in an electro-Fenton-electro-coagulation experiment.

[0081] As can be seen from the figure, after four cycles of testing, the removal rate of aniline reached 98%, and the effluent met the discharge standards. After five cycles of testing, the removal rate of aniline still reached over 95%, indicating that the modified cathode has good stability.

[0082] Comparative Example 1

[0083] Carbon felt (7cm×5cm×0.2mm, deposition area 70cm²) was deposited. 2 Immerse in ethanol solution and ultrasonically clean for 30 minutes. Repeat the above cleaning process twice, then ultrasonically clean with ultrapure water multiple times. After that, place in a vacuum drying oven to dry for later use.

[0084] Comparative Example 2

[0085] (1) Deposit carbon felt (7cm×5cm×0.2mm, with a deposition area of ​​70cm²) 2 Immerse in ethanol solution and ultrasonically clean for 30 minutes. Repeat the above cleaning process twice, then ultrasonically clean with ultrapure water multiple times, and finally place in a vacuum drying oven to dry.

[0086] (2) The pretreated carbon felt was immersed in a 30wt% nitric acid aqueous solution for 12 hours and then dried.

[0087] Comparative Example 3

[0088] (1) Deposit carbon felt (7cm×5cm×0.2mm, with a deposition area of ​​70cm²) 2 Immerse in ethanol solution and ultrasonically clean for 30 minutes. Repeat the above cleaning process twice, then ultrasonically clean with ultrapure water multiple times, and finally place in a vacuum drying oven to dry.

[0089] (2) The pretreated carbon felt was immersed in a 30wt% phosphoric acid aqueous solution for 12 hours and then dried.

[0090] Application performance testing:

[0091] The same test conditions (pH=3.0) as in Example 1 were used, except that the carbon felt prepared in Comparative Example 1 and the modified carbon felt prepared in Comparative Examples 2 and 3 were used as cathodes.

[0092] Tests showed that when the nitric acid-modified carbon felt prepared in Comparative Example 2 was used as the cathode, the degradation rates of aniline and Sb(V) were 72.88% and 100%, respectively, after 120 min of electro-Fenton-electrocoagulation treatment. When the phosphoric acid-modified carbon felt prepared in Comparative Example 3 was used as the cathode, the degradation rates of aniline and Sb(V) were 40.86% and 59.3%, respectively, after 120 min of electro-Fenton-electrocoagulation treatment. However, when the carbon felt prepared in Comparative Example 1 was used as the cathode, the degradation rates of aniline and Sb(V) were 6.59% and 100%, respectively, after 120 min of electro-Fenton-electrocoagulation treatment.

[0093] The modified carbon felt electrodes prepared in Comparative Examples 2 and 3 showed certain advantages in aniline removal compared to carbon felt electrodes that had only undergone pretreatment. This may be because the carbon felt electrodes impregnated with nitric acid and phosphoric acid can have N, O, and P functional groups attached to their surface, which facilitates the two-electron reduction reaction of O2 to generate H2O2, which then... 2+ Under the action of , ·OH is generated to oxidize aniline, which promotes the increase of aniline degradation rate; however, the aniline content in the wastewater after treatment still does not meet the discharge standards for dyeing and printing wastewater.

[0094] In addition, both nitric acid-modified carbon felt electrode and carbon felt electrode can achieve 100% removal of Sb(V), while phosphoric acid-modified carbon felt electrode has a certain inhibitory effect on the removal of Sb(V).

[0095] Comparative Example 4

[0096] The preparation process is basically the same as in Example 1, except that the hydroxylated carbon nanotubes in step (2) are replaced with carbon nanotubes of equal mass.

[0097] Comparative Example 5

[0098] The preparation process is basically the same as in Example 1, except that the hydroxylated carbon nanotubes in step (2) are replaced with carboxylated carbon nanotubes of equal mass.

[0099] The same application performance test conditions (pH=3.0) as in Example 1 were used, except that the cathode was replaced with the modified carbon felt electrode prepared in Comparative Example 4 and Comparative Example 5, respectively. The test results are listed in Table 2 below.

[0100] Table 2

[0101]

[0102]

[0103] As shown in Table 2, carbon felt modified with carbon nanotubes, hydroxylated carbon nanotubes, and carboxylated carbon nanotubes all effectively promoted aniline degradation compared to unmodified carbon felt electrodes. However, only the carbon felt electrode modified with hydroxylated carbon nanotubes could meet the effluent concentrations of aniline and Sb(V) in the wastewater treated by the carbon felt electrode, which meet the requirements of the "Water Pollutant Discharge Standard for Textile Dyeing and Finishing Industry" GB4287-2012 (which stipulates that the emission of aniline is less than 1 mg / L and the emission of Sb(V) is less than 0.1 mg / L).

[0104] Examples 2-5

[0105] The preparation process is basically the same as in Example 1, except that the mass of the hydroxylated carbon nanotubes in step (2) is replaced with 0.25g, 0.50g, 0.75g, and 1.50g in sequence.

[0106] The H2O2 accumulation was tested under the same conditions as in Example 1 (pH = 3.0), except that the cathode was replaced with the modified carbon felt cathode materials prepared in Examples 2 to 5 respectively. The accumulation of H2O2 within 120 min is shown in Table 3 below.

[0107] Table 3

[0108] serial number Example 1 Example 2 Example 3 Example 4 Example 5 <![CDATA[H2O2 concentration [mg / L]]]> 638.83 258.05 286.74 312.08 630.68

[0109] The same application performance test conditions (pH=3.0) as in Example 1 were used, except that the cathode was replaced with the modified carbon felt electrode prepared in Examples 2 to 5 respectively. The test results are listed in Table 4 below.

[0110] Table 4

[0111]

[0112] Table 4 shows that the change in the content of hydroxylated carbon nanotubes has a significant impact on aniline removal, but no significant impact on Sb(V) removal. Based on the analysis of the above data, it is possible that as the content of hydroxylated carbon nanotubes increases, the content of CNTs as electron transport carriers also increases, which is beneficial to the efficient reaction; however, when the loading reaches a certain value, the number of side reactions in the system increases, such as Fe... 2+ +·OH→Fe 3+ +OH - The consumption of ·OH leads to a decrease in the degradation rate.

[0113] Examples 6-9

[0114] The preparation process is basically the same as in Example 1, except that the mass of the polytetrafluoroethylene emulsion in step (2) is replaced with 0.5g, 3g, 5g and 7g respectively.

[0115] The cumulative amount of H2O2 was tested under the same conditions as in Example 1 (pH = 3.0), except that the cathode was replaced with the modified carbon felt cathode materials prepared in Examples 6 to 9 respectively. The cumulative amount of H2O2 within 120 min is shown in Table 5 below.

[0116] Table 5

[0117] serial number Example 1 Example 6 Example 7 Example 8 Example 9 <![CDATA[H2O2 concentration [mg / L]]]> 638.83 290.648 581.49 541.71 468.56

[0118] The same application performance test conditions (pH=3.0) as in Example 1 were used, the only difference being that the cathode was replaced with the modified carbon felt electrode prepared in Examples 6-9 respectively. The test results are shown in Table 6.

[0119] Table 6

[0120]

[0121] Tables 5 and 6 show that the highest H2O2 accumulation and optimal aniline removal occur when the mass ratio of hydroxylated carbon nanotubes to polytetrafluoroethylene (PTFE) is 1:1. Based on the analysis of these data changes, it is possible that insufficient PTFE content leads to uneven dispersion of the hydroxylated carbon nanotubes, preventing them from being stably loaded onto the carbon felt and hindering normal cyclic experiments. Increasing the PTFE content can enhance the hydrophobicity of the electrode material and promote H2O2 generation, but due to its non-conductive nature, it increases the electrode resistance, resulting in a decrease in the current response value.

[0122] Examples 10-12

[0123] The preparation process is basically the same as in Example 1, except that the calcination temperature in step (4) is replaced with 200℃, 280℃ and 450℃ respectively.

[0124] The H2O2 accumulation was tested under the same conditions as in Example 1 (pH = 3.0), the only difference being that the cathode was replaced with the modified carbon felt cathode materials prepared in Examples 10-12.

[0125] The cumulative amount of H2O2 within 120 min is shown in Table 7.

[0126] Table 7

[0127] serial number Example 1 Example 10 Example 11 Example 12 <![CDATA[H2O2 concentration [mg / L]]]> 638.83 267.50 367.12 158.78

[0128] The same application performance test conditions (pH=3.0) as in Example 1 were used, except that the cathode was replaced with the modified carbon felt electrode prepared in Examples 10-12 respectively. The test results are shown in Table 8.

[0129] Table 8

[0130]

[0131] Experiments revealed that calcination temperature primarily affects the film-forming properties of polytetrafluoroethylene (PTFE). Excessively high temperatures may damage the film structure, preventing hydroxylated carbon nanotubes from being stably loaded onto the carbon felt, leading to a decrease in H₂O₂ production and consequently a reduction in aniline removal efficiency.

[0132] Application performance testing:

[0133] 1. The modified carbon felt prepared in Example 1 was used as the cathode, and the same test conditions as in Example 1 were employed, except that the pH values ​​of the wastewater to be treated were adjusted to 2, 4, 5, and 6, and the electro-Fenton-electrocoagulation treatment time was adjusted to 40 min for all cases. The degradation of aniline and Sb(V) in the wastewater at different pH values ​​was as follows: Figure 4 As shown.

[0134] Depend on Figure 4 It is known that strong acidity (pH=2) is not conducive to the removal of aniline and Sb(V). When pH≥3, the removal efficiency of aniline decreases with increasing pH. When pH=3, aniline can be 100% removed after 40 minutes of treatment. When pH≥3, Sb(V) has excellent removal efficiency, and a removal rate of nearly 100% can be achieved in just 10 minutes.

[0135] 2. The modified carbon felt prepared in Example 1 was used as the cathode, and the same test conditions as in Example 1 were employed, except that the current for the electro-Fenton-electrocoagulation treatment was adjusted to 0.1A, 0.15A, and 0.25A, and the treatment time was adjusted to 40 min for all cases. The degradation of aniline and Sb(V) in wastewater under different currents is shown below. Figure 5 As shown.

[0136] Depend on Figure 5 It is known that the removal efficiency of aniline and Sb(V) increases with increasing current. When the current is too low, although the energy consumption is small, the concentration of pollutants in the effluent does not meet the discharge standards; when the current is too high, although the pollutants can be rapidly degraded, the energy consumption is high, resulting in high treatment costs. The preferred current is 0.2A.

[0137] 3. The modified carbon felt prepared in Example 1 was used as the cathode, and the same test conditions as in Example 1 were employed, except that the NaCl concentration in the wastewater to be treated was adjusted to 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, and 0.25 mol / L, and the electro-Fenton-electrocoagulation treatment time was adjusted to 40 min. The degradation of aniline and Sb(V) in the wastewater under different electrolyte concentrations is shown below. Figure 6 As shown.

[0138] Depend on Figure 6It is known that the degradation rate of aniline decreases after the electrolyte concentration increases to a certain value. As the electrolyte concentration increases, the conductivity of the system increases, which is beneficial for pollutant removal. However, excessively high concentrations can lead to an increase in previously insignificant side reactions within the system, resulting in a decrease in the ·OH content, which in turn prevents the efficient degradation of aniline. The preferred electrolyte concentration is 0.15 mol / L.

[0139] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. The specific examples used above to illustrate the present invention are only for the purpose of helping to understand the present invention and are not intended to limit the present invention. Those skilled in the art to which this invention pertains can make several simple deductions, modifications, substitutions, or combinations based on the concept of the present invention. These deductions, modifications, substitutions, or combinations also fall within the scope of the claims of the present invention.

Claims

1. A method for in-situ preparation of hydrogen peroxide, characterized in that, Water is used as the electrolyte, aluminum plate is used as the anode, and carbon felt loaded with hydroxylated carbon nanotube cathode material is used as the cathode; The method for preparing the carbon felt-supported hydroxylated carbon nanotube cathode material includes the following steps: Step 1: Mix hydroxylated carbon nanotubes, binder, and solvent to obtain a dispersion; The solvent is selected from a mixed solution of water and alcohol, with a volume ratio of water to alcohol of 10:0.5~2; The alcohol is selected from one or more of methanol, ethanol, and isopropanol; In the dispersion, the mass ratio of hydroxylated carbon nanotubes is 0.01~0.5 g / mL; Step 2: Immerse the pretreated carbon felt in the dispersion prepared in Step 1, and dry it after thorough immersion. Step 3: The product after drying in step 2 is calcined and cooled to obtain the carbon felt-supported hydroxylated carbon nanotube cathode material. The mass ratio of hydroxylated carbon nanotubes to binder is 1:1~5; The adhesive is selected from polytetrafluoroethylene; The calcination temperature is 280~360℃; The electrolyte has a pH value of 3 to 5.

2. The method for in-situ preparation of hydrogen peroxide according to claim 1, characterized in that, In step 2: The pretreatment of the carbon felt includes washing and drying; The mass ratio of the hydroxylated carbon nanotubes added in step 1 to the area of ​​the carbon felt is 3~22 mg / cm². 2 .

3. The method for in-situ preparation of hydrogen peroxide according to claim 1, characterized in that, In the preparation method of the carbon felt-supported hydroxylated carbon nanotube cathode material: The mass ratio of hydroxylated carbon nanotubes to binder is 1:1~3; The mass-to-area ratio of hydroxylated carbon nanotubes to carbon felt is 14–22 mg / cm². 2 ; The calcination temperature is 360℃; The electrolyte has a pH value of 3 to 4.

4. The method for in-situ preparation of hydrogen peroxide according to claim 1, characterized in that, In the preparation method of the carbon felt-supported hydroxylated carbon nanotube cathode material: The mass ratio of hydroxylated carbon nanotubes to binder is 1:1; The mass ratio of hydroxylated carbon nanotubes to the area of ​​the carbon felt was 14.29 mg / cm². 2 ; The electrolyte has a pH value of 3.

5. A method for treating aniline and Sb(V) in dyeing and printing wastewater using an electro-Fenton-electrocoagulation process, characterized in that, An iron plate was used as the anode, and a carbon felt-loaded hydroxylated carbon nanotube cathode material was used as the cathode. The method for preparing the carbon felt-supported hydroxylated carbon nanotube cathode material includes the following steps: Step 1: Mix hydroxylated carbon nanotubes, binder, and solvent to obtain a dispersion; The adhesive is selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride, and polyvinylidene fluoride. The solvent is selected from a mixed solution of water and alcohol, with a volume ratio of water to alcohol of 10:0.5~2; The alcohol is selected from one or more of methanol, ethanol, and isopropanol; In the dispersion, the mass ratio of hydroxylated carbon nanotubes is 0.01~0.5 g / mL; Step 2: Immerse the pretreated carbon felt in the dispersion prepared in Step 1, and dry it after thorough immersion. Step 3: The product after drying in step 2 is calcined and cooled to obtain the carbon felt-supported hydroxylated carbon nanotube cathode material. The mass ratio of hydroxylated carbon nanotubes to binder is 1:1; The mass ratio of hydroxylated carbon nanotubes to the area of ​​the carbon felt was 14.29 mg / cm². 2 ; The calcination temperature is 360℃.

6. The method for treating aniline and Sb(V) in dyeing and printing wastewater using the electro-Fenton-electrocoagulation process according to claim 5, characterized in that, In step 2: The pretreatment of the carbon felt includes washing and drying.

7. The method for treating aniline and Sb(V) in dyeing and printing wastewater using the electro-Fenton-electrocoagulation process according to claim 5, characterized in that: The pH value of the dyeing and printing wastewater is 3.0; The concentration of electrolyte in the dyeing and printing wastewater is 0.15 mol / L; The current used in the electro-Fenton-electrocoagulation process is 0.2~0.25A.

Images