Preparation and application of an oxygen-modified carbon catalyst with tunable surface carbon group number

Abstract

This invention discloses the preparation and application of an oxygen-modified carbon catalyst with adjustable surface carbon group number. The catalyst is prepared by using Ketjen black as a carbon substrate and ethylenediaminetetraacetic acid as an oxygen source, through stepwise oxygen addition (including surface oxidation and pyrolysis of oxygen-containing precursors) to modify the carbon substrate, thus obtaining the target catalyst. The number (concentration) of carbonyl groups at activated persulfate sites on the catalyst surface can be controlled by adjusting the pyrolysis temperature or by modifying the surface with glutaraldehyde or / and dansyl hydrazine. This concentration change causes an electron distribution between adjacent carbonyl groups, i.e., the intersitu spacing effect; utilizing this effect, efficient purification of water bodies contaminated with organic pollutants and effective soil remediation can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to an oxygen-modified carbon catalyst with adjustable surface carbon group number and its application in the removal of organic pollutants from environmental water bodies by activated persulfate. Background Technology

[0002] Persulfate activation, as an advanced oxidation technology, has wide and profound applications in environmental water treatment, in-situ soil remediation, animal tumor treatment, and chemical synthesis due to its ability to release strong oxidizing species. The reactive species released in this process include highly oxidizing free radicals, such as sulfate radicals (SO42-). ·- 2.5-3.1V NHE ), hydroxyl radicals ( · OH, 1.8-2.7V NHE Even superoxide anion radicals (O2) ·- -0.28V NHE In terms of environmental water remediation, these free radicals exhibit excellent degradation and mineralization capabilities for organic pollutants in water, especially in laboratory-scale water treatment experiments. However, in practical water or soil remediation engineering applications, the highly oxidizing free radical species released by this technology often fail to effectively remove organic pollutants. This is because real-world media, such as water bodies, have varying water quality conditions (e.g., variable pH) and complex compositions, containing different natural organic matter and inorganic anions. Therefore, inducing the release of highly efficient active species for the targeted and selective degradation of organic pollutants, while avoiding interference from the complex components of the water body, is both necessary and urgent.

[0003] The above-mentioned active species with highly efficient and selective degradation of organic pollutants include non-radical singlet oxygen (…). 1 O2, 2.2V NHEThis process involves electron transfer and oxidation of high-valence metals. A significant characteristic of this process is its mild reaction and selective degradation of target organic matter. This increases the greenness of water or soil remediation processes and avoids catalyst over-oxidation, reducing reaction costs. Based on the actual needs of water treatment, the core step in the effective pathway of inducing active species generated during persulfate activation lies in the rational design of the catalyst. Widely reported metal-based catalysts exhibit difficulties in recycling metal valence states during persulfate activation in water remediation, leading to easy deactivation and dissolution of metal catalytic sites. This not only results in high catalyst preparation costs but also increases the possibility of secondary pollution. Therefore, carbon-based non-metallic catalysts show promising application prospects. These catalysts not only overcome the shortcomings of metal-based catalysts but also possess unique advantages, such as low cost, tunable electronic structure, and effective catalysis in acidic or alkaline media. Common modification methods for carbon-based catalysts include modification with boron, nitrogen, sulfur, or phosphorus elements to alter the in-plane electronic structure and activate inert carbon substrates. These modified elements often constitute catalytic sites on the carbon substrate for persulfate activation. To date, there are few reports on using oxygen-modified carbon substrates to construct active sites for activated persulfate, and even fewer reports on the effect of the intersite distance effect (i.e., the distance between adjacent catalytic sites) on the removal of organic pollutants from water by activated persulfate. Summary of the Invention

[0004] The purpose of this invention is to provide an oxygen-modified carbon catalyst, a method for quantitatively adjusting the carbonyl groups on the surface of the catalyst, and its application in activating persulfate to remove organic pollutants.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An oxygen-modified carbon catalyst is prepared by the following steps:

[0007] Step 1: Surface oxidation of Ketjen Black is performed using nitric acid solution;

[0008] Step 2: Disperse oxidized Ketjen black in deionized water, then add the oxygen source ethylenediaminetetraacetic acid and the activator dicyandiamide in sequence. After mixing evenly, dry the mixture, grind it, and then pyrolyze it under an inert gas atmosphere to obtain an oxygen-modified carbon catalyst.

[0009] Further, in step 1, 80 mL of 6M nitric acid solution is added for every 200 mg of Ketjenblack.

[0010] Furthermore, the surface oxidation conditions in step 1 are 50–100°C for 6–24 hours.

[0011] Further, in step 2, 30 mg of oxidized Ketjen black is dispersed in 3 mL of deionized water, and then 2.05 g of ethylenediaminetetraacetic acid and 8 g of dicyandiamide are added sequentially.

[0012] Furthermore, the pyrolysis conditions in step 2 are 650–900℃ and 1–3 hours.

[0013] Furthermore, glutaraldehyde or dansyl hydrazine were used to modify the oxygen-modified carbon catalyst to control the number of carboxyl groups distributed on the catalyst surface.

[0014] The above-mentioned oxygen-modified carbon catalysts are used in the activation of persulfate.

[0015] The above-mentioned oxygen-modified carbon catalysts are used in the catalytic degradation of organic pollutants in water and / or soil.

[0016] Furthermore, the oxygen-modified carbon catalyst is used to catalyze the degradation of organic pollutants in water and / or soil by persulfate.

[0017] In one specific embodiment of the present invention, persulfate is preferably perdisulfate (PDS).

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) Non-metallic carbon-based catalysts are prepared by one-step pyrolysis. The preparation process is green, environmentally friendly, simple and fast. All precursors are converted into valuable catalysts without generating metal residues or other wastes.

[0020] (2) This invention is the first to discover the activation of persulfate by oxygen-modified carbon-based catalysts for the remediation of organic pollutants in water and soil. Compared with widely reported metal-based catalysts, the remediation process in this invention has low catalyst preparation costs, high reaction efficiency, and no secondary pollution.

[0021] (3) It was discovered for the first time that the oxygen-containing functional groups at the catalytic sites of activated persulfate by oxygen-modified carbon-based catalysts can be quantitatively controlled according to treatment needs. By adjusting the concentration of carbonyl groups at the catalytic sites, the inter-site spacing effect can be changed, thereby regulating the efficiency of activated persulfate in removing organic pollutants. Attached Figure Description

[0022] Figure 1 Morphological characterization diagram and elemental analysis diagram of the prepared O / C-8.

[0023] Figure 2 The chemical composition analysis diagram of the prepared O / C-8 includes X-ray diffraction pattern and X-ray photoelectron spectrum.

[0024] Figure 3The effect of O / C-8 activated common oxidants on the degradation and removal of 2,4-dichlorophenol and the bond energy analysis of common oxidants are shown.

[0025] Figure 4 The diagram shows the effect of the prepared O / C-8 activated PDS in removing common recalcitrant organic pollutants from water and the effect of the above process in removing 2,4-dichlorophenol from soil.

[0026] Figure 5 The effect of the prepared O / C-8 activated PDS on removing total organic carbon of 2,4-dichlorophenol from water and soil.

[0027] Figure 6 Chemical composition analysis of oxygen and comparison of carbonyl content of O / CT catalysts prepared at different temperatures.

[0028] Figure 7 The graphs show the effects of O / CT catalysts prepared at different temperatures on the degradation of furfuryl alcohol organic matter, and the comparison between the carbonyl content on the catalyst and the degradation effect of furfuryl alcohol.

[0029] Figure 8 This is a graph showing the change in carbonyl content after O / C-8 modification, analyzed by X-ray photoelectron spectroscopy.

[0030] Figure 9 This is a graph showing the change in carbonyl content after O / C-8 modification, analyzed by Fourier transform infrared spectroscopy.

[0031] Figure 10 The graph shows the active species generated by the carbonyl-content O / C-8 activated PDS and its performance in degrading organic matter. Detailed Implementation

[0032] This invention prepares an oxygen-modified carbon nonmetallic catalyst and controls the concentration of the main catalytic functional group carbonyl group of the catalyst to activate persulfate to remove organic pollutants in water and soil, thus achieving effective application.

[0033] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0035] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0036] The treatment process using a catalyst in this invention is as follows:

[0037] (1) Application in water body treatment

[0038] ① Take 10 mg of the catalyst prepared in the following examples and add it to 100 mL of wastewater containing 10 mg / L of organic pollutants. The organic pollutants degraded in this invention include phenol, sulfamethoxazole, 2,4-dichlorophenol, bisphenol A and tetracycline, and the probe molecule furfuryl alcohol.

[0039] ② Stirring with a magnetic stirrer for 30 minutes to achieve adsorption-desorption equilibrium between the catalyst and organic matter.

[0040] ③ Subsequently, 5 mg of potassium persulfate (PDS) oxidant was added to induce a Fenton-like reaction to degrade and remove organic pollutants from the water.

[0041] ④ Take 0.5 mL of the reaction solution at the preset time, filter it through a membrane, and then analyze the concentration of the target organic compound by high performance liquid chromatography to evaluate the degradation performance of the system.

[0042] (2) Application in soil remediation

[0043] ① The actual soil sample came from the Jiangning Campus of China Pharmaceutical University. After removing impurities such as leaves, weeds, and fine stone particles, the soil sample was sieved through a 40-mesh sieve.

[0044] ②The screened soil was thoroughly mixed according to the ratio of 1 mg of 2,4-dichlorophenol per gram of soil, and the mixing method was to invert the soil mixer for 3 hours.

[0045] ③ Mix the soil containing organic pollutants with the catalyst at a ratio of 15 mg of catalyst per gram of soil. Mix the soil by inverting the soil mixer for 3 hours.

[0046] ④ Add 20 mM persulfate (PDS) solution to the above mixture to induce a Fenton-like reaction. The amount added is 1 mL per gram of soil sample. The organic pollutants are degraded by inverting the mixture in a stirrer (rotation speed is 80 rpm).

[0047] ⑤ Take 0.3g of soil sample and sonicate it with 3mL of n-hexane solution containing 10% formic acid (mass fraction) for 1 hour to fully mix it and extract the organic pollutant 2,4-dichlorophenol contained in the soil.

[0048] ⑥ The obtained extract was filtered through a membrane and then subjected to high-performance liquid chromatography (HPLC) to analyze the concentration of the target organic matter in order to evaluate the degradation performance of the system.

[0049] Example 1

[0050] I. Preliminary oxidation of carbon substrate

[0051] ① Take 200 mg of commercial Ketjen black and add it to a round-bottom flask containing 80 mL of 6 M nitric acid solution, and stir at 80 °C for 12 hours using a reflux condenser.

[0052] ② Wash the oxidized Ketjen black several times with ethanol and deionized water until the pH of the washing solution is close to neutral.

[0053] ③ Dry the treated Ketjen Black in an oven at 60°C for 12 hours for later use.

[0054] II. Preparation of Oxygen-Modified Carbon Catalysts

[0055] ① Disperse 30 mg of oxidized Ketjen black in 3 mL of deionized water and sonicate for 5 min while stirring to ensure uniform dispersion.

[0056] ② Add 2.05g of ethylenediaminetetraacetic acid to the above mixture, and sonicate for 10 minutes while stirring to make it evenly mixed.

[0057] ③ Add 8g of dicyandiamide to the above mixture and sonicate for 10 minutes while stirring to ensure uniform mixing.

[0058] ④ The above mixture is dried in an oven at 60°C for 12 hours, and the resulting solid mixture is ground again for 30 minutes to reduce the particle size of the substance.

[0059] ⑤ The above-ground mixture was pyrolyzed in a tube furnace under a nitrogen atmosphere for 2 hours, with a heating rate of 5℃ / min. The pyrolysis temperatures were set at 650, 700, 750, 800, and 900℃. After the tube furnace cooled naturally, the solid powder catalyst was removed and ground again. The resulting catalyst was named O / CT, where O represents oxygen, C represents a carbon substrate, and T represents the pyrolysis temperature. For example, the sample prepared by pyrolysis at 800℃ for 2 hours was named O / C-8. The carbonyl content on the catalyst surface was controlled by adjusting the pyrolysis temperature.

[0060] Figure 1 This is a characterization of the physical morphology and elemental doping of the catalyst O / C-8. Figure 1 Image a is a scanning electron microscope image of the catalyst, showing that the catalyst exhibits a coiled structure with a macroporous structure. Figure 1 Image a is a high-magnification transmission electron microscope (TEM) image of the catalyst. As shown in the image, the catalyst exhibits a two-dimensional loose porous structure, containing mesopores and even micropores. These pore sizes provide excellent sites for subsequent catalytic reactions. Figure 1 b's built-in image is Figure 1The selected area electron diffraction pattern in region b, with its ring-shaped halo structure, indicates the amorphous and uncertain nature of the material. This characteristic is beneficial for electron transfer during persulfate activation. This characterization conclusion is consistent with the scanning electron microscopy images. Figure 1 The reaction of c, d, e, and g reveals the elemental distribution of the catalyst, which contains only carbon and oxygen elements and is uniformly distributed. Figure 1 The elemental spectra in h further support this conclusion. These characterizations indicate that the catalyst contains only carbon and oxygen, with the oxygen element used to modify the carbon substrate.

[0061] Inspired by the above characteristics, Figure 2 a is the X-ray diffraction pattern of O / C-8, showing that the catalyst contains only (002) and (100) planes, representing an amorphous and graphitic structure, respectively. This is consistent with the above... Figure 1 The conclusions of the high-power transmission spectroscopy characterization in b are consistent. Figure 2 b and 2c analyzed the chemical composition of the catalyst, specifically the carbon and oxygen elements present. Figure 2 The C1s spectrum of b reveals carbon-carbon double and single bonds, a key characteristic of graphitization. It also contains some carbon-oxygen bonds and even trace amounts of nitrogen bonds. The carbon-oxygen bonds primarily originate from the precursor ethylenediaminetetraacetic acid (EDTA), while the trace nitrogen primarily comes from the precursor dicyandiamide. Here, EDTA mainly provides an oxygen source for oxygen-containing functional groups on the carbon substrate. A small amount of the precursor dicyandiamide acts as an activator, its volatilization during pyrolysis promoting the formation of a loose, porous structure in the catalyst, facilitating the adhesion of reactants. Figure 2 The O1s spectrum of b clearly shows that oxygen contains both carbon-oxygen double bonds (C=O) and carbon-oxygen single bonds (CO), which strongly validates the chemical composition analysis of carbon. This result demonstrates that oxygen modification on a carbon substrate primarily forms carbon-oxygen double bonds (C=O, carbonyl groups), which are widely reported to activate persulfates.

[0062] Figure 3 A) is the time distribution diagram of the removal of 2,4-dichlorophenol by common oxidants activated by O / C-8. The results show that O / C-8 has the worst activation performance for H₂O₂, almost failing to degrade organic matter. Sodium periodate (PI) has the next best performance. Persulfates (including permonosulfate PMS and perdisulfate PDS) have the best activation performance, degrading organic matter within 5 minutes. The different reactivity of O / C-8 with these oxidants is related to the bond energy of the oxidant. Figure 3 As shown in b. Considering both the price and reactivity of the oxidant, PDS was selected as the model oxidant in this invention.

[0063] exist Figure 3 Based on the experimental results, Figure 4b. O / C-8 activated PDS was used to degrade common but difficult-to-degrade organic pollutants in different environmental water bodies, including phenol, sulfamethoxazole, 2,4-dichlorophenol, bisphenol A, and tetracycline. The results show that these organic pollutants were degraded to varying degrees, with the degradation of 2,4-dichlorophenol, bisphenol A, and tetracycline showing the fastest rate, while the degradation of phenol and sulfamethoxazole showed relatively slow rates. This result indicates that the active species in the O / C-8 activated PDS system possess the characteristic of selectively degrading pollutants, rather than undergoing non-selective strong oxidative degradation. This characteristic gives the catalyst proposed in this invention the potential to effectively address the treatment of real-world water bodies. Because real-world water bodies have complex compositions, active species with selective degradation capabilities can meet this challenge.

[0064] Similarly, the O / C-8 activated PDS system described above was used to treat 2,4-dichlorophenol organic pollutants in soil. The results are as follows: Figure 4 As shown in b, in soil containing only 2,4-dichlorophenol, the concentration of 2,4-dichlorophenol did not decrease. This suggests that the soil ecosystem cannot spontaneously transform and migrate 2,4-dichlorophenol within the specified time frame (360 min). Furthermore, the addition of a certain amount of the oxidant PDS also failed to reduce the concentration of 2,4-dichlorophenol. This suggests that the complex soil environment lacks the capacity to activate PDS to remove 2,4-dichlorophenol. However, when O / C-8 and PDS are present simultaneously in the soil, the organic pollutant 2,4-dichlorophenol is significantly degraded, with its concentration almost dropping to zero within 360 min. This result strongly demonstrates that the O / C-8 activated PDS system of this invention can not only efficiently degrade organic matter in water bodies but also effectively remove organic matter from soil. Moreover, Figure 5 This represents the total organic carbon removal during the degradation of 2,4-dichlorophenol in the two systems described above. The experimental results reflect that the degradation of organic matter is a gradual mineralization process.

[0065] Figure 6 High-magnification X-ray photoelectron spectroscopy (HPS) spectra of oxygen in the O / CT catalysts prepared at different temperatures in Example 2 were analyzed. The characterization results show that the oxygen content remained essentially unchanged with increasing pyrolysis temperature. However, the carbonyl content gradually increased, from 12.76% in O / C-6.5 to 58.48% in O / C-9. Figure 6 e further summarized the carbonyl content in the O / CT series catalysts. These experimental results demonstrate the method proposed in this invention for controlling the carbonyl content on the O / CT surface. As mentioned earlier, the carbonyl groups on the catalyst surface can act as catalytic sites for activating PDS.

[0066] Figure 7 The results of the activation of PDS by the O / CT series catalysts to degrade furfuryl alcohol organic matter confirmed the above conclusion, namely that the carbonyl group can act as a catalytic site for activating PDS. Figure 7 The results show that O / CT series catalysts can effectively degrade furfuryl alcohol by activating PDS. Furthermore, with increasing pyrolysis temperature, the concentration of active species released by O / CT-activated PDS increases, and the degradation rate of furfuryl alcohol accelerates. Figure 7 b uses the first-order reaction kinetic constant (k value, min) -1 The reaction rate is described by the number of k (k) values. In the O / CT-activated PDS system, as the temperature increases, the rate of furfuryl alcohol degradation (k) increases. For example... Figure 7 As shown in c, the carbonyl content on the catalyst surface and the corresponding k values ​​for the degradation of furfuryl alcohol by activated PDS exhibit a good exponential fit relationship, with a confidence interval R. 2 =0.94. To further solidify this conclusion, we performed a linear fit between the logarithm of the k-value and the carbonyl content, as follows: Figure 7 As shown in d, R 2 =0.94. This experimental result strongly demonstrates that the carbonyl groups on the catalyst surface act as sites for activating PDS. This is the significance of regulating the carbonyl content.

[0067] Example 2

[0068] ① Using the O / C-8 catalyst prepared in Example 1 as a template, 100 mg of O / C-8 was added to 100 mL of glutaraldehyde solution (containing 50% water by volume), and stirred at room temperature for 5 hours and 15 hours respectively using a magnetic stirrer.

[0069] ② After the above reaction is completed, solid-liquid separation is performed in a vacuum filtration device using a filter membrane (0.2μm) to separate the O / C-8 catalyst and the glutaraldehyde solution.

[0070] ③ The O / C-8 catalyst treated above was washed with ethanol and deionized water 3 to 5 times, dried in an oven at 60°C for 12 hours, and then taken out for use.

[0071] The catalyst obtained after stirring for 5 hours was named O / C-8 (moderate), where "moderate" indicates a moderate carbonyl content. The catalyst obtained after stirring for 15 hours was named O / C-8 (excessive), where "excessive" indicates an excessive carbonyl content.

[0072] Example 3

[0073] ① Using the O / C-8 catalyst prepared in Example 1 as a template, 40 mg of O / C-8 was added to 30 mL of 115 nM dansyl hydrazine solution, and 1 mL of 0.1 M HCl solution was added to the solution. The mixture was stirred for 30 hours at room temperature and in the dark.

[0074] ② After the above reaction is completed, solid-liquid separation is performed in a vacuum filtration device using a filter membrane (0.2μm) to separate the O / C-8 catalyst and the solution.

[0075] ③ The O / C-8 catalyst treated above was washed with ethanol and deionized water 3 to 5 times, dried in an oven at 60°C for 12 hours, and then taken out for use.

[0076] The resulting catalyst was named O / C-8 (too little), where "too little" indicates that the carbonyl content is too low.

[0077] In addition to adjusting the carbonyl content on the catalyst surface by changing the temperature as in Example 1, this invention uses the glutaraldehyde modification method in Example 2 to increase the carbonyl content on the catalyst surface, and uses the dansyl hydrazine modification method in Example 3 to decrease the carbonyl content on the catalyst surface. Figure 8 As shown, O / C-8 (excessive) and O / CT (moderate) obtained in Example 3 showed excessive and moderate carbonyl content, respectively; while O / C-8 (insufficient) obtained in Example 4 showed insufficient carbonyl content in the chemical analysis of oxygen. Figure 8 i. The inventors quantitatively summarized the carbonyl content on O / C-8 (too little), O / C-8, O / C-8 (moderate), and O / C-8 (too much) catalysts. To further solidify this conclusion, the inventors used Fourier transform infrared spectroscopy (e.g., Figure 9 (As shown) characterizes the vibrational behavior of the functional groups in the four catalysts mentioned above. The results show that the wavenumbers are located in the range of 1600-1500 cm⁻¹. -1 The carbonyl vibrations between the catalysts increased sequentially in the O / C-8 (too low), O / C-8 (moderate), and O / C-8 (too high) catalysts. Other functional groups, such as C=C and CH, showed no significant changes. These experimental results indirectly demonstrate the differences between the methods used in Examples 2 and 3 to regulate the carbonyl groups on the catalyst surface compared to Example 1: the former involves surface modification, where the catalyst's main framework, such as specific surface area, remains essentially unchanged; the latter involves different pyrolysis temperatures, leading to different carbonyl contents, which may also cause differences in the degree of graphitization and specific surface area of ​​the catalyst. In practical applications, the appropriate method can be selected as needed.

[0078] at last, Figure 10 Electron paramagnetic resonance spectroscopy was used to characterize the concentrations of active species produced by PDS activation under O / C-8 (insufficient), O / C-8, O / C-8 (moderate), and O / C-8 (excessive) conditions. Using 2,2,6,6-tetramethylpiperidinone as a spin-trapping agent to capture the active species produced in these four systems, the intensity was highest in the O / C-8 (moderate) activated PDS system and lowest in the O / C-8 (insufficient) activated PDS system. This suggests that the concentration of active species produced by PDS activation is strongest when the carbonyl concentration is appropriate. See [link to article]. Figure 10b. Degrading furfuryl alcohol using the four systems described above yielded similar results. Specifically, the O / C-8 (moderate) activated PDS system exhibited the fastest degradation performance for furfuryl alcohol, while the O / C-8 (too little) system showed considerably slower degradation. Similarly, the four systems showed a similar trend in the degradation of 2,4-dichlorophenol, with an optimal carbonyl group concentration resulting in the best performance for PDS-activated degradation of 2,4-dichlorophenol.

Claims

1. An oxygen-modified carbon catalyst, characterized in that, It is prepared by the following steps: Step 1: Surface oxidation of Ketjen Black is performed using nitric acid solution; Step 2: Disperse oxidized Ketjen black in deionized water, then add ethylenediaminetetraacetic acid and dicyandiamide in sequence, mix evenly, dry the mixture, grind it, and then pyrolyze it under an inert gas atmosphere to obtain oxygen-modified carbon catalyst. In step 1, 80 mL of 6M nitric acid solution is added for every 200 mg of Ketjen Black, and the surface oxidation conditions are 50~100℃ for 6~24 hours; In step 2, 30 mg of oxidized Ketjen black is dispersed in 3 mL of deionized water, and then 2.05 g of ethylenediaminetetraacetic acid and 8 g of dicyandiamide are added sequentially. The pyrolysis conditions are 650-900 °C for 1-3 hours. Glutaraldehyde or dansyl hydrazine were used to modify oxygen-modified carbon catalysts to control the number of carboxyl groups distributed on the catalyst surface.

2. The application of the oxygen-modified carbon catalyst according to claim 1 in the activation of persulfate.

3. The application of the oxygen-modified carbon catalyst according to claim 1 in the catalytic degradation of organic pollutants in water and / or soil.

4. The application according to claim 3, characterized in that: The oxygen-modified carbon catalyst is used to catalyze the degradation of organic pollutants in water and / or soil by persulfate.

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