Inorganic salt-modified carbon-based catalyst and use thereof
By preparing an inorganic salt-modified carbon-based catalyst, the problems of environmental pollution and insufficient catalytic activity of sulfamethoxazole were solved, and the efficient removal of sulfamethoxazole antibiotic from water was achieved, which is fast, economical and environmentally friendly.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PHARM UNIV
- Filing Date
- 2024-07-12
- Publication Date
- 2026-07-31
AI Technical Summary
In the existing technology, the use of sulfamethoxazole has problems with bacterial resistance and environmental pollution, and existing carbon-based catalysts are insufficient in terms of catalytic activity.
Graphite-phase carbon nitride g-C3N4 was prepared using urea and dicyandiamide as carbon and nitrogen source precursors, and then mixed with inorganic salts such as sodium nitrate, potassium nitrate, zinc nitrate, and sodium chloride. The mixture was then subjected to high-temperature annealing polymerization to form a modified carbon-based catalyst, which was used to activate peroxymonosulfonate to remove sulfamethoxazole antibiotics from water.
It significantly improved the reaction rate and oxidation performance of the catalyst, achieved efficient removal of sulfamethoxazole, reduced the dosage of oxidant, expanded the applicable pH range, and maintained the stability and economy of the catalyst.
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Figure CN118892858B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of materials chemistry, specifically relating to an inorganic salt-modified carbon-based catalyst and its application. Background Technology
[0002] Sulfamethoxazole is a broad-spectrum antibacterial drug widely used clinically to treat various bacterial infections, such as urinary tract infections, enteritis, and pneumonia, and also for the prevention and treatment of animal diseases. However, the use of sulfamethoxazole also presents some problems, such as bacterial resistance and environmental pollution. Therefore, developing new sulfamethoxazole carriers and methods to reduce its environmental pollution are currently hot research topics. Advanced oxidation processes based on persulfate have shown excellent oxidation efficiency in removing recalcitrant organic pollutants.
[0003] The emergence of carbon-based catalysts has, to some extent, compensated for the shortcomings of metal catalysts. Inorganic salt activation, as a rapid, mild, and relatively environmentally friendly modification method, has shown significant advantages. It significantly increases catalyst yield through a foaming effect, forming a unique porous structure and enriching the surface-exposed active sites. These characteristics enable inorganic salt-activated carbon-based catalysts to exhibit extremely high efficiency in degrading pollutants, effectively compensating for the shortcomings of non-metallic catalysts in catalytic activity compared to metallic catalysts, and achieving a significant improvement in catalytic performance. Summary of the Invention
[0004] One objective of this invention is to provide an inorganic salt modified carbon-based catalyst, which is prepared by using urea and dicyandiamide as carbon and nitrogen source precursors to obtain graphitic carbon nitride g-C3N4, and then mixing it with inorganic salt solution and polyether F127 and then polymerizing it by high-temperature annealing.
[0005] Furthermore, the inorganic salt is sodium nitrate, potassium nitrate, zinc nitrate, or sodium chloride.
[0006] Furthermore, the carbon-based catalyst is prepared using the following steps:
[0007] Step 1: Mix urea and dicyandiamide evenly and place them in a tube furnace. Then, anneal and polymerize them at high temperature under an inert gas atmosphere to obtain graphitic carbon nitride g-C3N4.
[0008] Step 2: Dissolve the inorganic salt in deionized water, then add graphite phase carbon nitride g-C3N4 and polyether F127 to obtain a viscous mixture;
[0009] Step 3: The mixture from Step 2 is sonicated and dried to completely evaporate the moisture. The resulting solid is then ground and annealed and polymerized at high temperature in an inert gas atmosphere to obtain the carbon-based catalyst.
[0010] Furthermore, the ratio of inorganic salts, urea, dicyandiamide, polyether F127, and deionized water is 0.005-0.1g:5g:1g:0.5g:10mL.
[0011] Furthermore, the conditions for high-temperature annealing polymerization in step 1 are annealing at 300℃-600℃ for 2-4 hours. Preferably, annealing is performed at 550℃ for 2 hours.
[0012] Further, in step 3, the drying conditions are 60℃-90℃ for 8-12 hours, and the high-temperature annealing polymerization conditions are 600-900℃ for 1-3 hours. Preferably, the drying conditions are 80℃ for 12 hours, and the high-temperature annealing polymerization conditions are 900℃ for 2 hours.
[0013] A second objective of this invention is to provide the application of the above-mentioned carbon-based catalyst in the catalytic degradation of organic pollutants.
[0014] Furthermore, the carbon-based catalyst is used to catalyze the degradation of water pollutants by oxidants.
[0015] Furthermore, the oxidant is peroxymonosulfonate or perdisulfate.
[0016] Furthermore, the contaminant is sulfamethoxazole.
[0017] This invention relates to a metal-free carbon-based catalyst prepared by high-temperature annealing and polymerization of an inorganic salt solution with a precursor containing only carbon and nitrogen elements. This non-metallic carbon-based catalyst is added to wastewater containing sulfamethoxazole antibiotics, followed by the addition of potassium peroxide monosulfonate to activate the peroxide monosulfonate and remove organic pollutants from the water containing sulfamethoxazole antibiotics. In this invention, the non-metallic carbon-based catalyst activates potassium peroxide monosulfonate, generating a strong oxidizing substance to remove sulfamethoxazole antibiotics from the wastewater. The carbon-based catalyst is added to the wastewater containing sulfamethoxazole antibiotics, and the mixture is stirred to achieve adsorption-desorption equilibrium of the pollutants. After equilibrium is reached, potassium peroxide monosulfonate is added to react with the catalyst.
[0018] Studies have found that sodium nitrate (an inorganic salt) can act as a foaming agent, effectively regulating pore size distribution and transforming the morphology into an uneven surface and multi-layered folded structure, with more distorted and disordered lattice fringes and numerous defects appearing on the surface of the carbon network. The performance of removing sulfamethoxazole antibiotic by activating peroxymonosulfonate (PMS = 0.1 mM) was significantly enhanced, with the pseudo-first-order reaction kinetic constant reaching a maximum of 0.30 min. -1 It is 3.57 times more effective than carbon-based materials without sodium nitrate doping. This catalyst also demonstrates a significant advantage in removing organic pollutants compared to other reported systems using carbon-based catalysts to activate persulfate for organic pollutant removal.
[0019] The present invention has the following beneficial effects:
[0020] (1) The sodium nitrate-doped dual-template carbon-based catalyst prepared in this invention can rapidly remove sulfamethoxazole antibiotic-contaminated water bodies, when W gC3N4 :W F127 :W NaNO3 When the ratio is 1:0.5:0.005, the fastest reaction rate is achieved within 10 min, resulting in 96.2% removal of 2.5 mg / L sulfamethoxazole solution, with a pseudo-first-order kinetic constant of 0.30 min. -1 Compared to carbon-based catalysts without sodium nitrate doping (W gC3N4 :W F127 The ratio of sodium nitrate to carbon nitride is 1:0.5, which is 3.57 times the reaction rate, indicating that activating carbon nitride with trace amounts of sodium nitrate has a significant advantage.
[0021] (2) Oxidant dosage: In this invention, the oxidant dosage is 0.1M potassium peroxymonosulfonate (PMS). The addition of a small amount of oxidant not only saves reaction costs but also reduces catalyst loss, which is beneficial for the repeated operation of the catalyst.
[0022] (3) Carbon-based catalysts doped with potassium nitrate, carbon-based catalysts doped with zinc nitrate, and carbon-based catalysts doped with sodium chloride synthesized under similar conditions can all achieve the same technical effect.
[0023] (4) Carbon-based catalysts synthesized with different amounts of sodium nitrate exhibit different performance in activating persulfate systems. When trace amounts of sodium nitrate are added, the removal efficiency of methaxaazole sulfonate antibiotics is significantly increased. The foaming and confinement effects of inorganic salts can improve the microstructure of carbon. However, when the sodium nitrate content is too high, the degradation efficiency decreases. Characterization methods confirm that the addition of sodium nitrate results in an uneven surface and a multi-layered folded structure. The lamellae are thinner, and the lattice fringes are more distorted and disordered. The uneven folded structure of the surface can effectively increase the specific surface area, generate more defects and active sites, which is beneficial for the adsorption and removal of organic pollutants.
[0024] (5) The catalyst of the present invention can effectively degrade sulfamethoxazole in a wide pH range (3-11), indicating that its doping with sodium nitrate has a wide range of applications in carbon-based catalysts. Attached Figure Description
[0025] Figure 1 The images show the morphology and Raman spectrum of the carbon-based catalyst synthesized in Example 1.
[0026] Figure 2 The graph shows the performance of the carbon-based catalyst synthesized in Example 1 in removing sulfamethoxazole antibiotic. Detailed Implementation
[0027] 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.
[0028] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.
[0029] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Example 1
[0030] The preparation of a carbon-based catalyst doped with sodium nitrate includes the following steps:
[0031] (1) Mix 2 g of urea and 1 g of dicyandiamide evenly and place them in a tube furnace. Under the protection of inert nitrogen gas, the mixture is annealed at 550 °C for 2 h to obtain yellow g-C3N4.
[0032] (2) Dissolve sodium nitrate solid (0.1 g, 0.05 g, 0.01 g, 0.005 g) in 10 mL of deionized water, and then mix 1 g of yellow g-C3N4 and 0.5 g of polyether F127 with it and stir to make it into a yellow viscous mixture.
[0033] (3) The mixture was ultrasonicated and then dried in an oven at 80°C for 12 hours to allow the moisture to evaporate completely. The resulting solid was then thoroughly ground and polymerized at 900°C for 3 hours under an inert nitrogen atmosphere. After cooling, the resulting solid was used to obtain sodium nitrate modified carbon-based catalyst NC-N.
[0034] Among them, W gC3N4 :W F127 :W NaNO3 =1:0.5:0.005-0.1.
[0035] Meanwhile, carbon-based catalysts NC-V and W without inorganic salt doping were prepared using the above methods. gC3N4 :W F127 =1∶0.5.
[0036] Comparing catalysts doped with different proportions of sodium nitrate, Figure 1 In the image a, we see a scanning electron microscope (SEM) image of NC-V. After doping with F127, the morphology changes to an uneven surface and a multi-layered folded structure, with the lattice stripes becoming more distorted and disordered. Figure 1 b is NC-N(W) gC3N4 :W F127 :W NaNO3Scanning electron microscopy (SEM) images of a carbon matrix (ratio 1:0.5:0.005) show that the addition of sodium nitrate forms an ultrathin, dense, sheet-like structure. As the temperature increases, the sodium nitrate transforms into sodium nitrite and oxygen, and F127 is pyrolyzed to form a highly conductive carbon network. Simultaneously, the gas generates numerous nanobubbles within the carbon matrix, causing the surrounding atoms to stretch and increasing the surface curvature. Numerous defects and pores appear on the carbon network surface, exposing more active sites. Figure 1 c represents the Raman spectra of carbon-based catalysts doped with different proportions of sodium nitrate. The NC-N Raman spectra of the materials show two typical D and G bands, with the D band (≈1350 cm⁻¹) being the largest. −1 ) and G-band (approximately 1520cm) -1 ) respectively correspond to sp 2 The intensity ratio of defects and vibrations of bonded carbon atoms was used to assess the proportion of defects and disordered structures in carbon materials. As the proportion of sodium nitrate increased, the intensity ratio decreased, indicating that using only trace amounts of sodium nitrate produced more effective defects during carbonization, activating F127 and exposing more active sites.
[0037] Carbon-based catalysts doped with potassium nitrate (NC-K), zinc nitrate (NC-Z), and sodium chloride (NC-A) were prepared using the above methods, wherein the mass ratio of g-C3N4, F127, and inorganic salt was 1:0.5:0.05.
[0038] The process of catalytic degradation of wastewater using the above-mentioned carbon-based catalyst is as follows:
[0039] ① Add 0.1 g / L of the synthesized carbon-based catalyst to 50 mL of sulfamethoxazole antibiotic wastewater with a concentration of 2.5 mg / L; ② Stir for 30 min to achieve adsorption-desorption equilibrium of the catalyst on the pollutants; ③ After equilibrium is reached, add 0.1 mM potassium peroxymonosulfonate and start timing the reaction; ④ At a preset time point, take 0.8 mL of the sample and add it to 0.8 mL of sodium thiosulfate solution (concentration of 1.6 g / L) to terminate the reaction; ⑤ Inject the sample into high performance liquid chromatography to detect the concentration of residual sulfamethoxazole antibiotic to determine the removal efficiency.
[0040] Figure 2 Figure 'a' shows the performance curves of carbon-based catalysts synthesized with different proportions of sodium nitrate for removing sulfamethoxazole antibiotics. The catalyst with 0.005 g of sodium nitrate (1:0.5:0.005) (NC-N) showed a 34% higher degradation rate of sulfamethoxazole than the catalyst without sodium nitrate (NC-V). As the proportion of sodium nitrate increased, the performance of NC-N in removing sulfamethoxazole antibiotics decreased. Figure 1 According to Raman spectroscopy, the lower the doping level, the greater the defects in the material, the more active sites are exposed, and the better the degradation effect. Figure 2 Figure b shows the rate constants of catalyst NC-N (1:0.5:0.005) with a sodium nitrate doping ratio of 0.005 g and catalyst NC-V without sodium nitrate doping. The pseudo-first-order reaction kinetic constant of NC-N is 0.30 min. -1 Compared to NC-V without sodium nitrate, the reaction rate is 3.57 times that of NC-V without sodium nitrate, indicating that activating carbon nitride with trace amounts of sodium nitrate has considerable advantages. Figure 2 Figure c shows the performance of NC-N doped with 0.005 g of sodium nitrate under different pH conditions in removing sulfamethoxazole antibiotic. This material exhibits good degradation ability over a wide pH range. Figure 2 Figure d shows the degradation effect of sulfamethoxazole by catalysts NC-N (1:0.5:0.05), NC-K (1:0.5:0.05), NC-Z (1:0.5:0.05), and NC-A (1:0.5:0.05) synthesized under the same conditions, respectively doped with sodium nitrate, potassium nitrate, zinc nitrate, and sodium chloride. The results show that trace salt template doping can significantly improve the catalytic performance of carbon-based materials, providing a good idea and method for carbon-based catalysis.
Claims
1. An inorganic salt-modified carbon-based catalyst, characterized by, Graphite-phase carbon nitride g-C3N4 was prepared by using urea and dicyandiamide as carbon and nitrogen source precursors, and then mixed with inorganic salt solution and polyether F127 and polymerized by high-temperature annealing. The inorganic salt is sodium nitrate, potassium nitrate, zinc nitrate or sodium chloride. The carbon-based catalyst is prepared using the following steps: Step 1: Mix urea and dicyandiamide evenly and place them in a tube furnace. Then, anneal and polymerize them at high temperature under an inert gas atmosphere to obtain graphitic carbon nitride g-C3N4. Step 2: Dissolve the inorganic salt in deionized water, then add graphite phase carbon nitride g-C3N4 and polyether F127 to obtain a viscous mixture; Step 3: The mixture from Step 2 is sonicated and dried to completely evaporate the moisture. The resulting solid is then ground and annealed and polymerized at high temperature in an inert gas atmosphere to obtain the carbon-based catalyst. The ratio of inorganic salt, urea, dicyandiamide, polyether F127 and deionized water is 0.005-0.1g:5g:1g:0.5g:10mL.
2. The carbon-based catalyst according to claim 1, characterized in that, The conditions for high-temperature annealing polymerization in step 1 are annealing at 300℃-600℃ for 2-4 hours.
3. The carbon-based catalyst according to claim 1, characterized in that, In step 3, the drying conditions are 60℃-90℃ for 8-12 hours, and the high-temperature annealing polymerization conditions are 600-900℃ for 1-3 hours.
4. The application of the carbon-based catalyst according to claim 1 in the catalytic degradation of organic pollutants.
5. The application according to claim 4, characterized in that, The carbon-based catalyst is used for the catalytic oxidation and degradation of pollutants in water bodies.