A thioxanthione derivative carbon catalyst and a preparation method and application thereof

Abstract

The application provides a thioxanthene quinone derivative carbon catalyst and a preparation method and application thereof, and belongs to the technical field of carbon materials. The derivative carbon catalyst is prepared by using sodium sulfide and 2,3-dichloro-1,4-naphthoquinone as raw materials, first synthesizing a purple solid organic matter precursor, and then adopting a pyrolysis method under anoxic conditions to prepare the derivative carbon catalyst with strong PMS catalytic capacity. The generation of key active sites quinone groups on the surface of the derivative carbon depends on the fact that the precursor contains 6 quinone groups, a large number of active sites are provided, and most of the quinone groups are retained in the pyrolysis process. With the advantage that the organic quinone groups synthesized by the precursor are rich in content, the abundance of the quinone groups on the surface of the derivative carbon catalyst obtained under the pyrolysis condition is increased. The derivative carbon catalyst can efficiently remove organic pollutants such as tetracycline, bisphenol A, sulfamethoxazole, sulfadimidine or ciprofloxacin in water.

Description

Technical Field

[0001] This invention relates to the field of carbon materials technology, and in particular to a thioheteroquinone-derived carbon catalyst, its preparation method, and its application. Background Technology

[0002] Advanced oxidation processes (AOPs) have garnered significant interest from researchers due to their powerful ability to remove organic pollutants. Traditional AOPs primarily utilize hydrogen peroxide (H₂O₂) as an oxidant to generate hydroxyl radicals (OH⁻). · In recent years, the emergence of sulfate radical advanced oxidation processes (SR-AOPs) has demonstrated its unique advantages. Sulfate radicals (SO4) ·- ) and OH · Compared to SO42, it has a higher redox potential. ·- E0 = 2.5–3.1 V, OH · (E0 = 1.9–2.7 V), with a longer half-life (SO4). ·- (30-40 μs, OH < 1 μs), exhibiting enhanced selectivity and a wider pH range for application. In the field of SR-AOPs, persulfate (PMS) and perdisulfate (PDS) are widely used as SO42-. ·- Precursors. PMS has an asymmetric structure and exhibits higher reactivity than PDS. PMS activation techniques include a range of methods, such as energy-based activation, transition metal activation, and non-metallic carbon activation. However, energy-based activation of PMS requires continuous energy input, placing high demands on energy levels. Furthermore, metal-based activation carries the risk of toxic metal leaching, inducing secondary pollution. In contrast, carbon catalysts offer advantages over metal catalysts, including environmental friendliness and strong thermal stability. However, the high cost of raw materials and complex preparation processes of carbon catalysts present significant challenges.

[0003] Carbon materials (CMs) are considered one of the most promising alternatives to traditional transition metal catalysts due to their excellent chemical stability, environmental friendliness, and tunable surface properties. However, the raw materials used to prepare these CMs are mostly expensive, and the catalyst preparation process is complex. From an application perspective, developing carbon materials with simple preparation processes, environmental friendliness, and low cost is urgently needed. Research results indicate that quinone groups in CMs can promote redox reactions and improve redox efficiency. Furthermore, research on CMs activating persulfate degradation of organic pollutants mainly focuses on the catalytic degradation process in different environmental media, lacking research on the design of carbon material structures and the exploration of active sites. The lack of active sites greatly hinders the high efficiency of catalysis. Therefore, how to develop and design CMs with abundant active sites, simple processes, and environmental friendliness is a problem that urgently needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings of the prior art by providing a thioheterocyclic quinone-derived carbon catalyst, its preparation method, and its application. This derivative carbon catalyst uses sodium sulfide nonahydrate (Na2S·9H2O) and 2,3-dichloro-1,4-naphthoquinone (DCNQ) as raw materials. First, a purple solid organic precursor is synthesized. Then, under anaerobic conditions, a pyrolysis method is used to prepare a derivative carbon catalyst with strong PMS catalytic ability, which can efficiently remove organic pollutants such as tetracycline, bisphenol A, sulfamethoxazole, sulfadiazine, or ciprofloxacin from water.

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

[0006] The first objective of this invention is to provide a method for preparing a thioheteroquinone-derived carbon catalyst, comprising the following specific steps:

[0007] S1. Sodium sulfide nonahydrate and 2,3-dichloro-1,4-naphthoquinone are mixed in a certain mass ratio, an appropriate amount of water is added, and the mixture is stirred at a first preset temperature for a first preset time; then, tetrachlorobenzoquinone and N,N-dimethylformamide are added, and the mixture is stirred at a second preset temperature for a second preset time to obtain a first mixture;

[0008] S2. The first mixture is added to an ice bath aqueous solution, and crystals precipitate out; after filtration, washing and vacuum drying, a crude purple solid precipitate is obtained.

[0009] S3. Dissolve the crude product obtained in step S2 in N,N-dimethylformamide solution and recrystallize to obtain a purified purple solid precipitate, which is the precursor.

[0010] S4. The precursor obtained in step S3 is calcined and pyrolyzed under oxygen-deficient conditions to obtain a thioheteroquinone-derived carbon catalyst.

[0011] Furthermore, in step S1, the mass ratio of sodium sulfide nonahydrate, 2,3-dichloro-1,4-naphthoquinone, and tetrachlorobenzoquinone is (2.76–8.28):(2–3):(1–2).

[0012] Furthermore, the first preset temperature is 90℃~120℃, and the second preset temperature is 80~85℃.

[0013] Furthermore, in step S4, under a nitrogen atmosphere, the heating rate is 3℃ / min, the slow calcination pyrolysis temperature is 700℃~1000℃, and the pyrolysis time is 1.5~2h.

[0014] A second objective of this invention is to provide a thioheteroquinone-derived carbon catalyst prepared by the above-described preparation method.

[0015] A third objective of this invention is to provide the application of the above-mentioned thioheteroquinone-derived carbon catalyst in the removal of organic pollutants from water.

[0016] Furthermore, the organic pollutant includes any one of tetracycline, bisphenol A, sulfamethoxazole, sulfadiazine, or ciprofloxacin.

[0017] The fourth objective of this invention is to provide a method for removing organic pollutants from water, comprising adding persulfate and the aforementioned sulfur-containing heterocyclic quinone-derived carbon catalyst to the water, wherein the organic pollutants include any one of tetracycline, bisphenol A, sulfamethoxazole, sulfadiazine, or ciprofloxacin.

[0018] Furthermore, the dosage of the thioheteroquinone-derived carbon catalyst is 0.1–0.4 g·L⁻¹. -1 The dosage of persulfate is 0.6–6 g·L. -1 .

[0019] Furthermore, the pH of the water body is 3.02 to 10.02.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] (1) This invention provides a thioheterocyclic quinone-derived carbon catalyst, its preparation method, and its application, belonging to the field of novel catalyst technology. This derivative carbon catalyst uses sodium sulfide nonahydrate (Na2S·9H2O) and 2,3-dichloro-1,4-naphthoquinone (DCNQ) as raw materials. First, a purple solid organic precursor is synthesized. Then, under anaerobic conditions, a pyrolysis method is used to prepare a derivative carbon catalyst with strong PMS catalytic activity. The formation of quinone groups at key active sites on the surface of the derivative carbon depends on the presence of six quinone groups in the synthesized precursor, providing a large number of active sites. Most of the quinone groups are retained during pyrolysis. Taking advantage of the abundant quinone content in the synthesized organic precursor, the abundance of quinone groups on the surface of the derivative carbon catalyst obtained under pyrolysis conditions is increased, resulting in a significant removal effect on organic pollutants, especially TC.

[0022] (2) The catalytic system constructed by the thioheteroquinone-derived carbon catalyst and PMS of the present invention generates active oxide species. 1 O2 drives the efficient degradation of TC. 1 O2 is generated partly from the self-decomposition of PMS and partly from the redox reaction of PMS induced by C=O on the surface of the derived carbon. Compared to the free radical pathway, TC degradation is more efficient and involves more degradation pathways in this system, starting with the cleavage of CH and CN bonds, followed by a series of hydroxylation, demethylation, and benzene ring opening, ultimately being mineralized into NH4. + H2O and CO2.

[0023] (3) The thioheteroquinone-derived carbon catalyst provided by this invention is less affected by anions or organic matter in water, opening up a new way for constructing new, efficient, green and inexpensive biochar-based environmental functional materials, providing new technologies, methods and theoretical basis for the remediation of TC pollution in water bodies, and has a very good application prospect. Attached Figure Description

[0024] Figure 1 SEM, TEM, HAADF-STEM, and elemental distribution diagrams of the SHQC-9 derived carbon catalyst;

[0025] Figure 2a XRD patterns of the derived carbon catalysts at different pyrolysis temperatures;

[0026] Figure 2b Raman spectra of the derived carbon catalysts at different pyrolysis temperatures;

[0027] Figure 2c FTIR spectra of the derived carbon catalysts at different pyrolysis temperatures;

[0028] Figure 3a High-resolution C1s spectra of derived carbon catalysts at different pyrolysis temperatures;

[0029] Figure 3b High-resolution O1s spectra of derived carbon catalysts at different pyrolysis temperatures;

[0030] Figure 3c High-resolution S2p spectra of derived carbon catalysts at different pyrolysis temperatures;

[0031] Figure 3d High-resolution O1s spectrum of SHQC-9 material;

[0032] Figure 4a A comparison of the degradation of TC by different SHQCs materials;

[0033] Figure 4b A comparison of the changes in pseudo-second-order rate constants for different SHQCs materials;

[0034] Figure 4c The logarithm log(k) of TC degradation efficiency and A C＝O / A C-O A comparison chart of ratios;

[0035] Figure 4d This is a comparison chart of the degradation of different organic pollutants by SHQC-9 material;

[0036] Figures 5a-5d The effects of different quenchers on TC degradation are shown below.

[0037] Figures 6a-6c The images show the EPR spectra at different reaction times in the SHQC-9 / PMS system.

[0038] Figures 7a-7d The images show a comparison of high-resolution spectra of C1s, O1s, and S2p before and after the reaction of SHQC-9, and a comparison of the degradation of TC by SHQC-9 and SHQC-9-PH.

[0039] Figures 8a-8c The figures show the degradation of TC by different dosages of SHQC-9, the degradation of TC by different concentrations of PMS, and the degradation of TC at different pH values.

[0040] Figures 9a-9d The figures show the performance evaluation results of the SHQC-9 / PMS catalyst system in actual water bodies. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0042] All reagents used in this invention are commercially available.

[0043] In the embodiments, field emission scanning electron microscopy was used to characterize the surface morphology of the modified and reacted samples. Specific surface area and average pore size were measured using a specific surface area analyzer. Fourier transform infrared spectroscopy and a potassium bromide pellet test method were used to determine and identify the functional groups on the surface of the modified and reacted samples. X-ray diffraction was used to observe the crystal structure of the samples. X-ray photoelectron spectroscopy was used to analyze the changes in elemental and chemical composition of the sample surface before and after modification and reaction. Raman spectroscopy was used to analyze the chemical and structural information of defects and crystallinity in the samples.

[0044] TC degradation experiment:

[0045] Degradation experiments were conducted at room temperature (20±5℃), and pH adjustment was not required unless otherwise specified. Specifically, 50 mL of a 20 mg·L⁻¹ solution was prepared in a 100 mL beaker. -1 A certain concentration of PMS solution and a certain mass of derivatized carbon sample were added to a TC solution, and the reaction was started under magnetic stirring at a rate of 400 r / min. -1 At selected time intervals, collect 1 mL of sample from the system and immediately flush with 1 mL of 0.01 mol·L⁻¹ solution. -1The solution was quenched with sodium thiosulfate (Na₂S₂O₃) solution. The mixed solution was then filtered through a 0.22 μm organic filter membrane for high-performance liquid chromatography (HPLC) analysis. Single-factor experimental design was used to investigate the effects of catalyst dosage, pH value, and actual water background components (Cl₂). - H2PO4 - SO4 2- NO3 - The effect of humic acid on TC oxidative degradation was investigated. In the pH effect experiment, a phosphate buffer solution was used to control the pH value of the solution. To examine the stability of the material, the derived carbon after the reaction was collected and gently rinsed with methanol. After washing and drying, the material was recycled several times under the same operating conditions, and its reusability was evaluated in conjunction with its TC removal efficiency. To ensure the accuracy and reliability of the experimental data, each experiment was conducted in at least 2-3 parallel trials, and the mean and standard deviation were calculated.

[0046] The English abbreviations used in this invention are explained as follows:

[0047] TC: Tetracycline; BPA: Bisphenol A; SMX: Sulfamethoxazole; SMZ: Sulfamethazine; CIP: Ciprofloxacin; TBA: Tert-Butanol; BQ: P-benzoquinone; FFA: Furfuryl alcohol; DMPO: 5,5-Dimethyl-1-pyrrolidone N-oxide; TEMP: 2,2,6,6-Tetramethyl-4-piperidinone hydrochloride.

[0048] Example 1

[0049] This embodiment provides a method for preparing a thioheteroquinone-derived carbon catalyst.

[0050] The specific process is as follows:

[0051] Step S1: 5.52 g of sodium sulfide nonahydrate (Na2S·9H2O) and 2.3 g of 2,3-dichloro-1,4-naphthoquinone (DCNQ) were mixed in a three-necked flask, and an appropriate amount of water was added. The mixture was heated and stirred at 90–120 °C for 9 hours. Subsequently, 1.3 g of tetrachlorobenzoquinone (TCBQ) and an appropriate amount of DMF were added, and the mixture was stirred and heated at 80 °C for 2 hours. The mixture was then poured into an appropriate amount of ice water, which immediately formed a large amount of purple solid precipitate. The mixture was filtered and washed several times alternately with ethanol and pure water. The solid was then vacuum dried at 80 °C for 9 hours. Finally, the purple solid precipitate was purified by recrystallization from DMF.

[0052] Step S2: The solid precipitate obtained in step S1 is used to prepare a carbon sample by anaerobic pyrolysis. Under N2 atmosphere, the heating rate is 3℃ / min, and pyrolysis is carried out at 700℃ for 2 hours. The resulting sample is labeled SHQC-7, and the derived carbon particles are obtained by grinding and sieving.

[0053] The inventors discovered in their research that the catalytic effect of carbon materials obtained without grinding is comparable to that obtained by grinding and sieving.

[0054] Example 2

[0055] This embodiment provides a method for preparing a thioheteroquinone-derived carbon catalyst.

[0056] The specific process is basically the same as in Example 1, except that it is pyrolyzed at 800°C for 2 hours under N2 atmosphere, and the resulting sample is labeled SHQC-8.

[0057] Example 3

[0058] This embodiment provides a method for preparing a thioheteroquinone-derived carbon catalyst.

[0059] The specific process is basically the same as in Example 1, except that it is pyrolyzed at 900°C for 2 hours under N2 atmosphere, and the resulting sample is labeled SHQC-9.

[0060] Example 4

[0061] This embodiment provides a method for preparing a thioheteroquinone-derived carbon catalyst.

[0062] The specific process is basically the same as in Example 1, except that it is pyrolyzed at 950°C for 2 hours under N2 atmosphere, and the resulting sample is labeled SHQC-9.5.

[0063] Example 5

[0064] This embodiment provides a method for preparing a thioheteroquinone-derived carbon catalyst.

[0065] The specific process is basically the same as in Example 1, except that it is pyrolyzed at 1000°C for 2 hours under N2 atmosphere, and the resulting sample is labeled SHQC-10.

[0066] Comparative Example 1

[0067] This comparative example provides a method for preparing derivative carbon by influencing the C=O content of sodium sulfide nonahydrate (Na2S·9H2O) of different masses.

[0068] The specific process is as follows: Step S1: Mix 2.76g to 11.04g of sodium sulfide nonahydrate (Na2S·9H2O) with 2.3g of 2,3-dichloro-1,4-naphthoquinone (DCNQ) in a three-necked flask, add an appropriate amount of water, and heat and stir at 100℃ for 9 hours; then add 1.3g of tetrachlorobenzoquinone (TCBQ) and an appropriate amount of DMF, and heat and stir at 80℃ for 2 hours; then pour the mixture into an appropriate amount of ice water, and a large amount of purple solid precipitate will immediately form; filter the mixture, wash it several times alternately with ethanol and pure water, and then dry the solid under vacuum at 80℃ for 9 hours; finally, purify the purple solid precipitate by recrystallization from DMF.

[0069] Step S2: The solid precipitate obtained in step S1 is used to prepare carbon samples by anaerobic pyrolysis. Under N2 atmosphere, the pyrolysis is carried out at 900℃ for 2 hours. The resulting samples are labeled as Na2S·9H2O-1 / 2 and Na2S·9H2O-2, respectively. The samples are then ground and sieved to obtain derived carbon particles.

[0070] To better illustrate the performance of the thioheterocyclic quinone-derived carbon catalyst prepared in this invention, the applicant conducted the following studies:

[0071] Performance characterization:

[0072] refer to Figure 1 The morphology and structure of SHQC were analyzed using SEM. Sample SHQC-7 exhibited a prominent blocky structure on its surface. With increasing pyrolysis temperature, SHQC-8 showed a fragmented granular structure on its surface, mainly due to the release of volatile substances with increasing pyrolysis temperature. SHQC-9 possessed a non-porous, plate-like structure with a small number of wrinkles on its surface, containing embedded fine particles. The surface structure did not change significantly with further temperature increases. TEM was used to further investigate the pore structure of SHQC-9. TEM images revealed the presence of large interconnected pores within SHQC-9. Figure 1 (d) shows the high-angle annular dark-field scanning TEM (HAADF-STEM) image of SHQC-9. The EDS plot of SHQC-9 shows that the C, O, N, and S elements are evenly distributed, indicating the successful construction of quinone-derived carbon using thioheterocyclic quinones as precursors.

[0073] refer to Figure 2a The crystal structure of the derived carbon under different temperature conditions was analyzed by wide-angle XRD patterns. As shown in the figure, all samples exhibited two broad diffraction peaks at 25° and 43.3°, representing the (002) and (100) planes of crystalline carbon, respectively. The diffraction peak intensity slightly increased with increasing pyrolysis temperature from 700℃ to 1000℃, indicating that the increased temperature led to a higher degree of graphitization in the SHQC samples.

[0074] Raman spectroscopy was used to further analyze the graphitization and defect levels of SHQC, such as... Figure 2b As shown, 1340 and 1590cm -1 The characteristic peaks at these locations correspond to the D and G peaks of the derived carbon, respectively. The D peak corresponds to the sp peak where the derived carbon is connected to structural defects. 2 The vibrational plane of the bonded carbon structure, with the G peak corresponding to sp 2 Vibrational planes of bonded graphite-carbon structures. D / I G The ratio is a commonly used indicator to reflect the degree of defects in carbon materials. D / I G The higher the value, the more pronounced the defects in the carbon material. The I values ​​for SHQC-7, SHQC-8, SHQC-9, SHQC-9.5, and SHQC-10 are... D / I G The ratios were 0.89, 1.09, 1.21, 1.14, and 1.08, respectively. Among them, SHQC-9 had the highest defect degree, and the formation of defect sites could improve the catalytic performance of the derived carbon. With the increase of pyrolysis temperature (700℃~900℃), the released volatile substances and gases formed more pores in SHQC. With further increases in temperature (>900℃), organic sulfur was released into the gas phase, leading to the destruction of the derived carbon structure and the collapse of the pore structure. Table 1 shows the specific surface area, average pore size, and pore volume of all SHQC materials. With the increase of pyrolysis temperature, the specific surface area of ​​the prepared SHQC materials gradually increased. At a pyrolysis temperature of 900℃, the specific surface area reached 39.1811 m². 2 ·g -1 The average pore size increased to 50.7191 nm. This increase was mainly due to the release of more volatile substances and gases at higher pyrolysis temperatures, which significantly increased the specific surface area of ​​the material. Further increases in pyrolysis temperature led to the collapse of the derived carbon structure, resulting in a decrease in the average pore size of SHQC-10 to 5.9249 nm and a decrease in specific surface area to 6.2796 nm. 2 ·g -1 .

[0075] Table 1. Specific surface area and pore volume of SHQC

[0076]

[0077] To further investigate the surface functional groups of the derived carbon, FTIR analysis was performed on the samples. Figure 2c As shown, 3450cm -1 The peak at 1635 cm⁻¹ can be attributed to the vibrational stretching of the -OH group or water molecules. -1 1519cm -1 and 1020cm-1 The characteristic peaks at these locations correspond to the stretching vibrations of C-OH, C=O, and CO groups, respectively. With increasing pyrolysis temperature, unstable C-OH and CO gradually transform into C=O groups. At a calcination temperature of 900℃, sample SHQC-9 exhibits the highest number of C=O groups. (1113 cm⁻¹) -1 The peak at 667 cm⁻¹ is related to the tensile vibration of COC. -1 The peaks at the point are due to the stretching of CS, with the highest intensity of CS in SHQC-9, indicating successful S doping and a significant impact on the surface functional groups of the derived carbon.

[0078] refer to Figures 3a-3d The elemental composition and chemical environment of the SHQC surface were characterized using XPS. The main components of the sample were C, O, and S. Figure 3a The high-resolution C1s spectrum of the SHQC sample is shown, revealing peaks centered at 291 eV, 285.8 eV, and 284.5 eV, corresponding to C=O, CO, and CC groups, respectively. As the pyrolysis temperature increased from 700 °C to 900 °C, the proportion of C=O increased from 8.74% to 11.33%. The C=O / CO ratio increased from 0.14 to 0.24. Previous studies have reported that a higher C=O / CO ratio is beneficial for the degradation of organic pollutants in PMS systems. The O1s high-resolution spectrum also shows a corresponding trend. Figure 3b However, as the temperature rises to 1000℃, the C=O / CO ratio decreases, mainly due to the structural destruction of biochar at high temperatures, leading to surface group recombination. The S2p high-resolution spectrum of SHQC (…) Figure 3c The peak at 168.8 eV is attributed to the oxide of S (C-SOx-C), while the two peaks at 165.1 eV and 163.8 eV are attributed to thiophene S (CSC), a result of spin coupling. As the pyrolysis temperature increases from 700 °C to 900 °C, the proportion of thiophene S increases from 75.94% to 81.26%. Existing literature reports that thiophene S is beneficial for the degradation of organic pollutants in the system. (The text then abruptly shifts to a seemingly unrelated topic: embedded sp...) 2 The CSC in the hybrid carbon lattice can change the spin density of the surrounding carbon atoms, which is beneficial for PMS activation.

[0079] Example 6

[0080] This embodiment provides a method for preparing a thioheteroquinone-derived carbon catalyst.

[0081] The specific process is basically the same as in Example 1, except that: 2.76 g of sodium sulfide nonahydrate (Na2S·9H2O) and 2 g of 2,3-dichloro-1,4-naphthoquinone (DCNQ) were mixed and placed in a three-necked flask, and an appropriate amount of water was added. The mixture was heated and stirred at 90–120 °C for 9 hours; subsequently, 1 g of tetrachlorobenzoquinone (TCBQ) and an appropriate amount of DMF were added. The performance characteristics of the prepared thioheterocyclic quinone-derived carbon catalyst are similar to those in Example 1.

[0082] Example 7

[0083] This embodiment provides a method for preparing a thioheteroquinone-derived carbon catalyst.

[0084] The specific process is basically the same as in Example 1, except that: 8.28 g of sodium sulfide nonahydrate (Na2S·9H2O) and 3 g of 2,3-dichloro-1,4-naphthoquinone (DCNQ) were mixed and placed in a three-necked flask, and an appropriate amount of water was added. The mixture was heated and stirred at 90–120 °C for 9 hours; subsequently, 2 g of tetrachlorobenzoquinone (TCBQ) and an appropriate amount of DMF were added. The performance characteristics of the prepared thioheterocyclic quinone-derived carbon catalyst are similar to those in Example 1.

[0085] To better illustrate the excellent catalytic performance of the thioheterocyclic quinone-derived carbon catalyst prepared in this invention, the applicant conducted the following research:

[0086] 1. PMS catalytic performance evaluation of derived carbon catalysts

[0087] Using TC as the target pollutant, the catalytic performance of derived char samples prepared at different pyrolysis temperatures was evaluated. Experimental conditions: [TC]0 = 20 mg·L⁻¹ -1 [SHQC]0 = 0.1 g·L -1 [PMS]0 = 1.0 mmol·L -1 Initial pH≈4.6, T=20±10℃.

[0088] Figure 4a The catalytic degradation of TC is shown, with degradation rates of TC in the SHQC-7 / PMS, SHQC-8 / PMS, SHQC-9 / PMS, SHQC-9.5 / PMS, and SHQC-10 / PMS systems of 60.1%, 65.1%, 90.3%, 84.8%, and 71.0%, respectively. The above characterization results indicate that a higher pyrolysis temperature in the range of 700–900 °C can enhance the graphitization and defect structure of the derived carbon, while optimizing the C=O / CO ratio, thereby promoting its catalytic performance on PMS to a certain extent.

[0089] The experimental data were fitted with pseudo-second-order dynamics, such as... Figure 4bAs shown, the reaction rate constant of the SHQC-9 / PMS system is 0.04815 L·mg. -1 ·min -1 The reaction rate constants of 0.01338 L·mg, which are superior to those of the SHQC-7 / PMS, SHQC-8 / PMS, SHQC-9.5 / PMS and SHQC-10 / PMS systems, are respectively. -1 ·min -1 0.01542 L·mg -1 ·min -1 0.03959 L·mg -1 ·min -1 and 0.02005 L·mg -1 ·min -1 To further compare the effects of different pyrolysis temperatures on the catalytic performance of the derived carbon materials, we quantitatively analyzed the logarithm (log(k)) of the degradation rate constant of TC by SHQC in relation to structural parameters. For example... Figure 4c As shown, in the log(k) value and A C＝O / A C-O A strong linear relationship was observed between the ratios. Higher A C＝O / A C-O The ratio favors an increase in the log(k) value, which may be due to the formation of an abundance of electrons by the C=O group, thereby promoting the degradation reaction.

[0090] In addition, experiments were conducted on the SHQC-9 / PMS system to investigate the degradation of other contaminants [bisphenol A (BPA), sulfamethoxazole (SMX), sulfadiazine (SMZ), and ciprofloxacin (CIP, all at 10 mg / L]. Figure 4d As shown, the removal rates of BPA, SMX, SMZ, and CIP all exceeded 70% within 120 minutes. This indicates that the SHQC-9 / PMS system is suitable for the rapid oxidative removal of other organic matter in water.

[0091] 2. Study on the degradation pathway of TC in the SHQC-9 / PMS system

[0092] To identify the active substances in the reaction process, we conducted free radical scavenging and EPR experiments to determine the substances involved in TC degradation in the PMS system. Four different concentration gradients of scavengers were used to remove specific free radicals in the SHQC-9 / PMS system: MeOH for SO42- scavenging. ·- and OH · TBA removes OH · p-BQ removes O2 ·- FFA clearing 1 O2. MeOH can effectively quench OH-. ·(k = 1.6 ~ 7.8 × 10⁷ M) -1 S -1 ) and SO4 ·- (k = 1.2 ~ 2.8 × 10⁸ M) -1 S -1 TBA can effectively quench OH. · (k=3.8-7.6×10⁸M) -1 S -1 However, it is difficult to quench SO4. ·- (k=4.0-9.1×10⁵M) -1 S -1 ).from Figure 5a and 5b As can be seen, different concentrations of MeOH and TBA have little effect on TC degradation, indicating that the reaction is mainly unaffected by free radicals. · OH and SO4 ·- ) control. Figure 5c The results showed that the reaction rate slowed down significantly with increasing p-BQ concentration, indicating that O2... ·- The impact on the performance of the SHQC-9 / PMS system · OH and SO4 ·- Larger. However, p-BQ could not completely inhibit degradation, indicating the possible presence of non-radical pathways in the system. Singlet oxygen (SO4), a typical non-radical reactive substance in the SHQC-9 / PMS system, was detected using FFA. 1 O2). For example Figure 5d As shown, when the FFA concentration increased from 5 mM to 20 mM, the degradation rate of TC decreased from 80.08% to 54.47%, indicating that... 1 O2 plays a dominant role in the degradation of TC.

[0093] To further analyze its degradation mechanism, DMPO and TEMP were used as trapping agents to capture active species. Figure 6a As shown, a heptagonal signal of 5,5-dimethylpyrrolline-(2)-oxo-(1)(DMPOX) was detected in the SHQC-9 / PMS system. This signal was previously reported by... 1 O2 or surface-activated complexes are directly oxidized to form this. Combined with free radical scavenging experiments, this further demonstrates... 1 O2 plays a major role in activating PMS in SHQC-9. Similarly, TEMP- was detected at the same sampling time. 1 O2 and DMPO-O2 ·- signal ( Figure 6b and 6c During PMS activation, the generated H2O2 reacts with... · OH reacts to produce HO2 · HO2· Decompose to generate O2 ·- Free radicals. Ultimately, O2 ·- Recombination of free radicals and O2 ·- and · The reaction between OH groups produces 1 O2.

[0094] To explore the active site of SHQC-9 in activating PMS, we used XPS to analyze SHQC-9 before and after activation. Figure 7a The images show the O1s spectra before and after the catalytic reaction. After the reaction, the C=O content on the SHQC-9 surface decreased significantly, while the CO and C-OH contents increased significantly. Figure 7b The C1s spectra revealed that the C=O content on the SHQC-9 surface decreased while the CO content increased after the reaction. This is because the C=O is oxidized during the reaction, acting as an intermediate in electron transfer. Furthermore, the lone pair electrons on the Lewis bases increase the electron density of adjacent carbocyclic rings, promoting the redox reaction of SHQC-9. Figure 7c The images show the S2p spectra before and after the catalytic reaction. The proportion of thiophene S on the SHQC-9 surface decreased from 81% before the reaction to 72% after the reaction. This indicates that thiophene S participates in the PMS activation process as an active site. Figure 2c The FT-IR spectra showed that the intensity of C=O in SHQC-9 decreased significantly after the reaction, while the intensities of COC and C-OH increased. Simultaneously, COC shifted to the lower wavenumber region. To determine the active sites of the SHQC-9 catalyst, phenylhydrazine (PH) was used as a masking agent to shield or remove surface ketones, quinones, and carbonyl groups. The SHQC-9 prepared after PH treatment is denoted as SHQC-9(PH). Figure 7d As shown, the degradation of TC in the BQC-10(PH) / PMS system was significantly reduced, further confirming that quinone groups are the main active sites for PMS oxidation.

[0095] Example 6

[0096] This example investigated the influence of catalyst / oxidant dosage on TC removal in the SHQC-9 / PMS system. Experimental conditions: [TC]0 = 20 mg / L -1 Initial pH≈4.6, T=20±10℃.

[0097] The specific process was as follows: Under experimental conditions controlling a single variable, the catalyst dosage of 0.1–0.4 g / L was studied. -1 The concentration of the oxidant is between 0.1 and 1.5 mmol / L. -1 Variation of TC removal rate within the specified range. Experimental conditions: [TC]0 = 20 mg / L -1Initial pH≈4.6, T=20±10℃.

[0098] like Figure 8a As shown, increasing the amount of SHQC-9 has a positive effect on TC degradation. When the catalyst dosage increased from 5 mg to 20 mg, the TC degradation efficiency increased from 88.8% to 91.4%, and the reaction rate constant increased from 0.04633 L·mg. -1 ·min -1 Increased to 0.05442 L·mg -1 ·min -1 This indicates that high doses of SHQC-9 provide additional active sites for TC adsorption and PMS activation, thereby affecting the catalytic degradation efficiency.

[0099] There is a direct correlation between PMS concentration and TC degradation rate. For example... Figure 8b As shown, in the range of 0.1–1.5 mmol / L -1 Within the specified range, increasing the initial PMS concentration enhanced the TC removal rate, increasing it from 69.3% to 91.0%, and the reaction rate constant from 0.02885 L·mg. -1 ·min -1 Increased to 0.05002 L·mg -1 ·min -1 .

[0100] Example 7

[0101] This embodiment investigates the influence of solution pH on TC removal in the SHQC-9 / PMS system.

[0102] The specific procedure involved using phosphate solution as a buffer to investigate the effect of solution pH on TC removal in the SHQC-9 / PMS system within the pH range of 3.02–10.02. Experimental conditions: [TC]0 = 20 mg / L -1 [SHQC]0 = 0.1g L -1 [PMS]0 = 1.0 mmol / L -1 Initial pH≈4.6, T=20±10℃.

[0103] like Figure 8c As shown, the TC removal efficiency of the SHQC-9 / PMS system remained above 70% consistently within a pH range of 3.02–9.18, indicating its effectiveness over a wide pH range. Kinetic analysis showed that acidic conditions were preferred for achieving higher degradation efficiency. Specifically, the reaction rate constant was 0.04815 L·mg at a solution pH of 4.56. -1 ·min -1reached its peak. In addition, in this study, PMS (pK a1 <0, pK a2 = 9.4) mainly exists in the form of anions (HSO5 - and SO5 2- ), while the calculated zero-point charge of SHQC-9 is 6.57 (pH pzc ≈ 6.57), indicating that under acidic conditions, the surface charge of SHQC-9 is mainly composed of positive charge centers. The electrostatic attraction between them will promote the removal of TC. TC usually exhibits three pKa values (pK a1 = 3.3, pK a2 = 7.7, pK a3 = 9.7). TC exists in different forms: H4TC when pH < 3.3 + , H3TC and H2TC when 3.3 < pH < 9.7 - , and HTC2 when pH > 9.7 - . When the pH value is lower than 3.3, SHQC-9 is positively charged, PMS mainly exists as HSO5 - , and TC mainly exists in the form of H4TC + , generating electrostatic repulsion and affecting the removal of TC. When the pH is between 3.3 and 6.57, SHQC-9 is positively charged, the TC molecule is negatively charged (H2TC - ), and PMS is negatively charged (HSO5 - , SO5 2- ). The electrostatic attraction can effectively enhance the adsorption of TC and PMS on the catalyst, thereby improving electron transfer and the activation of PMS. As the pH further increases, the negative charge on the surface of SHQC-9 increases with the increase of pH. TC mainly exists in the form of anions (H2TC - , HTC2 - ), and PMS mainly exists in the form of anions. The electrostatic repulsion between these species inhibits the removal of TC.

[0104] Example 8

[0105] In this example, the influencing factors of the presence of different anions and organic substances on the removal of TC in the SHQC-9 / PMS system were studied.

[0106] The specific process is as follows: Under the experimental conditions of controlling a single variable, the changes in the removal rate of TC in the presence of inorganic anions Cl - , SO4 2- , NO3 - and H2PO4 - and the organic substance HA were studied. Experimental conditions: [TC]0 = 20 mg·L -1 , [SHQC]0 = 0.1 g L-1 [PMS]0 = 1.0 mmol / L -1 Initial pH≈4.6, T=20±10℃.

[0107] The study investigated different inorganic anions (Cl). - SO4 2- NO3 - and H2PO4 - The effect of ) on the degradation of tetracycline (TC). For example Figure 9a As shown, SO4 2- NO3 - and H2PO4 - It has an inhibitory effect on the degradation of TC. This is attributed to the competitive interaction between the target pollutant and inorganic anions. With SO4... 2- NO3 - and H2PO4 - With increasing concentration, their inhibitory effect on TC degradation was not significant. Conversely, Cl... - The addition of [unclear] is beneficial for the degradation of TC. Cl - It can act as a catalyst for PMS to generate HOCl, promoting the decomposition of pollutants. Furthermore, Cl... · The formation of other active chlorine compounds, such as Cl2, also promotes the degradation of TC.

[0108] Humic acid (HA) inhibits the degradation of total toxicity (TC). For example... Figure 9b As shown, the HA concentration increased from 0 to 1 mg / L. -1 Correspondingly, the TC removal rate decreased from 90.3% to 66.0%. The inhibitory effect of HA may stem from competitive processes, including oxidation and adsorption competition between HA and TC. Furthermore, PMS and HA may exhibit adsorption competition on the SHQC-9 surface.

[0109] Example 9

[0110] This embodiment studies the removal efficiency of TC by the SHQC-9 / PMS catalyst system in actual water bodies.

[0111] Experimental conditions: [TC]0 = 20 mg / L -1 [SHQC]0 = 0.1g L -1 [PMS]0 = 1.0 mmol / L -1 Initial pH≈4.6, T=20±10℃.

[0112] To further investigate the stability and adaptability of the SHQC-9 / PMS system in real aquatic environments, we conducted experiments on TC removal in tap water and lake water (China University of Geosciences (Wuhan) Future City Campus, Wuhan, China), such as... Figure 9c As shown, the degradation efficiency of TC in tap water and lake water is comparable to that in pure water, indicating that the SHQC-9 / PMS system has the ability to treat tap water and lake water.

[0113] Example 10

[0114] This embodiment studies the reusability of the SHQC-9 / PMS catalyst.

[0115] Experimental conditions: [TC]0 = 20 mg / L -1 [SHQC]0 = 0.1g L -1 [PMS]0 = 1.0 mmol / L -1 Initial pH≈4.6, T=20±10℃.

[0116] like Figure 9d As shown, after the third cycle, the degradation efficiency dropped to approximately 84.2%. This decrease may be due to the adsorption of organic matter on the surface of SHQC-9, which limits the availability of active sites. However, the overall removal rate remained above 80%, indicating that SHQC-9 has good reusability.

[0117] For any points not covered above, existing technologies shall apply.

[0118] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a thioheterocyclic quinone-derived carbon catalyst, characterized in that, The specific steps include the following: S1. Sodium sulfide nonahydrate and 2,3-dichloro-1,4-naphthoquinone are mixed in a certain mass ratio, an appropriate amount of water is added, and the mixture is stirred at a first preset temperature for a first preset time. Subsequently, tetrachlorobenzoquinone and N,N-dimethylformamide were added, and the mixture was stirred at a second preset temperature for a second preset time to obtain a first mixture; S2. The first mixture is added to an ice bath aqueous solution, and crystals precipitate out; after filtration, washing and vacuum drying, a crude purple solid precipitate is obtained. S3. Dissolve the crude product obtained in step S2 in N,N-dimethylformamide solution and recrystallize to obtain a purified purple solid precipitate, which is the precursor. S4. The precursor obtained in step S3 is slowly calcined and pyrolyzed under oxygen-deficient conditions to obtain a thioheteroquinone-derived carbon catalyst.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of sodium sulfide nonahydrate, 2,3-dichloro-1,4-naphthoquinone and tetrachlorobenzoquinone is (2.76~8.28):(2~3):(1~2).

3. The preparation method according to claim 2, characterized in that, The first preset temperature is 90℃~120℃, and the second preset temperature is 80~85℃.

4. The preparation method according to claim 2, characterized in that, In step S4, under a nitrogen atmosphere, the slow calcination pyrolysis temperature is 700℃~1000℃, and the pyrolysis time is 1.5~2h.

5. A thioheteroquinone-derived carbon catalyst prepared by the method described in any one of claims 1-4.

6. The application of the thioheteroquinone-derived carbon catalyst as described in claim 5 in the removal of organic pollutants from water bodies.

7. The application as described in claim 6, characterized in that, The organic pollutants include any one of tetracycline, bisphenol A, sulfamethoxazole, sulfadiazine, or ciprofloxacin.

8. A method for removing organic pollutants from water, characterized in that, Add persulfate and the thioheteroquinone-derived carbon catalyst as described in claim 5 to the water body, wherein the organic pollutant includes any one of tetracycline, bisphenol A, sulfamethoxazole, sulfadiazine, or ciprofloxacin.

9. The method as described in claim 8, characterized in that, The dosage of the thioheteroquinone-derived carbon catalyst is 0.1~0.4 g·L. -1 The dosage of persulfate is 0.6~6 g·L. -1 .

10. The method as described in claim 9, characterized in that, The pH of the water body is 3.02~10.02.

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