Preparation method of Ag2NCN / BiVO4 and application of Ag2NCN / BiVO4 in photocatalytic degradation of glyphosate to generate phosphate
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-29
- Publication Date
- 2026-08-07
AI Technical Summary
过长的半衰期，造成其自然降解能力弱，在土壤和水生动物体内富集，对生态环境造成严重危害
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Abstract
Description
Technical Field
[0001] This invention mainly relates to the preparation of novel photocatalysts and the selective degradation of glyphosate, and particularly to the preparation of the novel Ag2NCN / BiVO4 photocatalyst and its application in the selective degradation of glyphosate. Background Technology
[0002] Transition metal carbodiimide materials are a novel type of functional material that has attracted widespread attention due to their unique electronic structure and spatial properties. Among them, [NCN]... 2- It exhibits a linear structure and, when combined with transition metals, forms new materials with broad molecular structures. [NCN] 2- It is an extremely strong σ-donor ligand, capable of binding with transition metals to give the "metal-NCN" structure a highly delocalized electron configuration; simultaneously, π electrons exist within [NCN]. 2- The flow between chemical bonds improves electron transport, thus increasing electron transport capacity and accelerating electron transfer. The addition of transition metals gives "metal-NCN" a linear or layered structure with regular lines. Its cubic stacking provides abundant porosity, maximizing the exposure of active sites and facilitating adsorption. Chemically, "metal-NCN" has the same coordination number, a larger valence band value, and a smaller conduction band number as metal oxides and metal sulfides, making it an excellent candidate for novel photocatalysis. In photocatalysis, single photocatalysts suffer from high carrier recombination rates, low visible light utilization, and low catalytic performance. To overcome these shortcomings, many studies have focused on the preparation of composite photocatalysts. However, the preparation of "metal-NCN / other photocatalysts" typically relies on high-temperature calcination, thermal activation, hydrothermal techniques, which consume a large amount of energy. Therefore, finding a method to synthesize "metal-NCN" catalysts at room temperature is crucial.
[0003] Glyphosate is a widely used herbicide globally. Excessive application of glyphosate causes serious pollution to soil, surface and groundwater runoff, and surrounding water bodies. Its long half-life results in poor natural degradation, leading to its accumulation in soil and aquatic animals, causing severe harm to the ecological environment. Complete degradation of glyphosate produces the final product phosphate (PO4). 3- Phosphorus in nature typically originates from ores, but phosphate rock has a low utilization rate and its recycling activity in nature is far less reactive than that of C and N. Therefore, finding ways to recover phosphorus resources is particularly important. During the bond-breaking process of glyphosate, by controlling the degree of oxidation of glyphosate, PO4 with resource recovery value can be generated. 3- This is a green resource utilization route with economic value. Summary of the Invention
[0004] To address the problems existing in the prior art, this invention provides a novel preparation method and application of Ag2NCN / BiVO4. The resulting Ag2NCN / BiVO4 is used for the photocatalytic degradation of glyphosate, simultaneously and selectively generating PO4 with resource recycling value. 3- .
[0005] This invention is achieved through the following technical solution: A method for preparing a metal carbodiimide / bismuth vanadate composite photocatalyst includes the following steps: Bismuth vanadate, carbodiimide source, and silver source are mixed in a polar solvent and reacted under light irradiation to generate a metal carbodiimide / bismuth vanadate composite photocatalyst.
[0006] The carbodiimide source is cyanamide (H2NCN), the silver source is silver nitrate (AgNO3), the polar solvent is water, and the illumination condition is visible light irradiation; preferably, the wavelength of the visible light is 420 nm, the reaction is carried out at room temperature, and an inert gas is introduced for protection during the reaction; preferably, the inert gas is nitrogen.
[0007] The silver ions (Ag) in the silver source + ) and the carbodiimide ions ([NCN]) in the carbodiimide source 2- The molar ratio of the substances is 1:0.1 to 1:5; preferably 1:0.5 to 1:2; more preferably 1:1.
[0008] Before adding the silver source, the mixture of bismuth vanadate, carbodiimide source and polar solvent is pre-illuminated for 5 to 10 minutes. After adding the silver source, the illumination time is continued for 10 to 90 minutes. Preferably, the illumination time after adding the silver source is 60 minutes.
[0009] The present invention also provides a metal carbodiimide / bismuth vanadate composite photocatalyst prepared according to the preparation method described above.
[0010] In the catalyst, silver carbodiimide Ag2NCN is supported on the surface of bismuth vanadate.
[0011] The application of the aforementioned metal carbodiimide / bismuth vanadate composite photocatalyst in the photocatalytic degradation of organophosphorus compounds.
[0012] The organophosphorus compound is glyphosate. The metal carbodiimide / bismuth vanadate composite photocatalyst is placed in wastewater containing glyphosate, and a photocatalytic degradation reaction is carried out under visible light irradiation to degrade glyphosate and convert it into phosphate ions (PO4) with resource recovery value. 3-The concentration of glyphosate in the wastewater is 50–150 μmol / L, preferably 100 μmol / L; the irradiation time with visible light is 10–90 min, preferably 90 min.
[0013] The photocatalytic degradation reaction has a selectivity of over 85% for phosphate ions.
[0014] A method for photocatalytic degradation of glyphosate and simultaneous recovery of phosphorus resources includes: mixing the aforementioned metal carbodiimide / bismuth vanadate composite photocatalyst with glyphosate-containing wastewater, reacting under visible light irradiation to obtain a reaction solution containing phosphate ions, wherein the reaction is carried out at room temperature and normal pressure; the visible light wavelength is 420 nm.
[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention uses decahedral bismuth vanadate (BiVO4) with visible light response as the catalyst substrate, with H2NCN uniformly dispersed in the solution. Under visible light irradiation, electrons converge on the (010) crystal plane of decahedral BiVO4, followed by the implantation of Ag. + It has the ability to accept electrons and rapidly accumulates on the (010) crystal plane of BiVO4. The N in H2NCN has a strong coordination effect with transition metals, and in Ag... + After addition, N-Ag bonds can be formed. An Ag₂NCN / BiVO₄ photocatalyst with a "metal-NCN" structure was synthesized at room temperature. The synthesized catalyst was used for the photocatalytic degradation of glyphosate, and it was found that the Ag₂NCN / BiVO₄ photocatalyst achieved a 100% degradation efficiency for 100 μmol / L glyphosate within 90 min. This invention has the following advantages: 1) The synthesis of the "metal-NCN" structure catalyst is carried out at room temperature, and N and Ag can coordinate and combine, making the synthesis process simple; 2) It can achieve complete degradation of glyphosate, with a phosphate generation rate of 85.4%, enabling the resource utilization of phosphorus.
[0016] This invention provides a method for preparing a novel Ag2NCN / BiVO4 photocatalyst, which is applied to the degradation of glyphosate, providing a good example for the removal of organic pollutants and the prospect of phosphorus resource utilization. Attached Figure Description
[0017] Figure 1 Infrared spectra of H2NCN, BiVO4 and Ag2NCN / BiVO4.
[0018] Figure 2 SEM and energy dispersive spectroscopy of Ag2NCN / BiVO4. Detailed Implementation
[0019] To further understand the present invention, the present invention will be described below with reference to embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.
[0020] Example 1 Add 5 mL of 0.2 mol / L H₂NCN solution to a mixture of 200 mg BiVO₄ and 80 mL of pure water, and continuously purge with N₂ for 15 min at room temperature. Irradiate the suspension under 420 nm visible light for 5 min, then add 560 μL of 0.1 mol / L AgNO₃ solution and irradiate continuously for 60 min. Filter the resulting solid and wash repeatedly with pure water and ethanol to obtain the Ag₂NCN / BiVO₄-first catalyst.
[0021] The obtained Ag₂NCN / BiVO₄-first catalyst was added to a 100 μmol / L glyphosate solution and placed under 420 nm visible light. After reacting for 90 min, the sample was taken out and derivatized with FMOC reagent for 4 h. Under the conditions of phosphoric acid aqueous solution: acetonitrile = 65:35, the degradation rate of GP reached 100% by high performance liquid chromatography. At the same time, the concentration of AMPA generated was 6.50 μmol / L, with a selectivity of 58.8%. The formation of PO₄ was detected by molybdate colorimetric method. 3- The concentration of [agent] was 61.67 μmol / L, with a selectivity of 61.67%; the concentration of generated H2O2, detected using a UV spectrophotometer, was 102.6 μmol / L. The chemical structures of the initial BiVO4, H2NCN, and the synthesized Ag2NCN / BiVO4-first photocatalyst were analyzed using infrared spectroscopy at 2163 cm⁻¹. -1 The presence of an N=C=N vibrational peak at the N=C=N position, which is somewhat shifted compared to H2NCN, indicates that Ag2NCN was successfully synthesized on the BiVO4 surface. Simultaneously, the material exhibits a novel morphology in SEM, with corresponding N and C peaks also appearing in the energy dispersive spectroscopy (EDS), demonstrating the successful synthesis of the Ag2NCN / BiVO4 photocatalyst using this new method.
[0022] Example 2 Similar to Example 1, but with the order of addition of AgNO3 solution and H2NCN solution during the synthesis process changed, while keeping other conditions unchanged, Ag2NCN / BiVO4-second catalyst was obtained.
[0023] The product obtained after a reaction of 90 min was tested using the method described in Example 1, and the conclusions are as follows: The degradation efficiency of Ag2NCN / BiVO4-second for 100 μmol / L glyphosate reached 91.6% within 90 min. The concentration of AMPA generated was 53.9 μmol / L, with a selectivity of 58.8%; PO4 was generated... 3- The concentration of [agent] was 17.3 μmol / L, with a selectivity of 18.9%. Simultaneously, the concentration of H2O2 generated was 61.3 μmol / L.
[0024] Therefore, it is evident that changing [NCN]... 2- and Ag + The order in which the catalyst is added will lead to different reactions on the BiVO4 surface during synthesis, resulting in different selectivity for glyphosate degradation. Adding H2NCN first can promote glyphosate degradation towards the formation of phosphate.
[0025] Example 3 Same as Example 1, except the volume of H2NCN solution added during stirring was changed to 28 μL, and the Ag and [NCN] content was adjusted. 2- With a molar ratio of 1:0.1 and other conditions remaining unchanged, an Ag2NCN / BiVO4- 1:0.1 catalyst was obtained.
[0026] The product obtained after a reaction of 90 min was tested using the method described in Example 1, and the conclusions are as follows: Ag2NCN / BiVO4-1:0.1 achieved a 100.0% removal rate of glyphosate. The concentration of AMPA generated was 43.5 μmol / L, with a selectivity of 45.3%; PO4 was generated... 3- The content was 45.3 μmol / L, and the selectivity was 43.5%.
[0027] Example 4 Similar to Example 1, but with the volume of H₂NCN solution added during stirring changed to 140 μL, and the molar ratio of Ag to NCN changed to 1:0.5, while keeping other conditions unchanged, an Ag₂NCN / BiVO₄⁻ 1:0.5 catalyst was obtained. The product obtained after 90 min of reaction was analyzed using the method described in Example 1, and the conclusions are as follows: Ag2NCN / BiVO4-1:0.5 achieved a glyphosate removal rate of 93.7%, generating AMPA at a concentration of 54.6 μmol / L with a selectivity of 58.3%; PO4 was also generated. 3- The content was 50.0 μmol / L, and the selectivity was 42.7%.
[0028] Example 5 Similar to Example 1, the volume of H₂NCN solution added during stirring was changed to 280 μL, and the molar ratio of Ag to NCN was changed to 1:1, while other conditions remained unchanged, resulting in an Ag₂NCN / BiVO₄⁻ 1:1 catalyst. The product obtained after 90 min of reaction was analyzed using the method described in Example 1, and the conclusions are as follows: Ag2NCN / BiVO4-1:1 achieved a 100.0% removal rate of glyphosate, with AMPA concentration at 0 μmol / L; PO4 was generated. 3- The content was 54.7 μmol / L, and the selectivity was 54.7%.
[0029] Example 6 Similar to Example 1, the volume of H₂NCN solution added during stirring was changed to 560 μL, and the molar ratio of Ag to NCN was changed to 1:2, while other conditions remained unchanged, resulting in an Ag₂NCN / BiVO₄⁻ 1:2 catalyst. The product obtained after 90 min of reaction was analyzed using the method described in Example 1, and the conclusions are as follows: Ag2NCN / BiVO4-1:2 achieved 100% removal of glyphosate, with AMPA formation at a concentration of 0 μmol / L and selectivity of 0%; PO4 was generated. 3- The content was 91.7 μmol / L, and the selectivity was 91.7%.
[0030] Example 7 Similar to Example 1, the volume of H₂NCN solution added during stirring was changed to 1400 μL, and the molar ratio of Ag to NCN was changed to 1:5, while other conditions remained unchanged, resulting in an Ag₂NCN / BiVO₄⁻ 1:5 catalyst. The product obtained after 90 min of reaction was analyzed using the method described in Example 1, and the conclusions are as follows: The Ag2NCN / BiVO4-1:5 method achieved a glyphosate removal rate of 73.8%, generating AMPA at a concentration of 42.3 μmol / L with a selectivity of 57.4%; PO4 was also generated. 3- The content was 11.4 μmol / L, and the selectivity was 15.4%.
[0031] It is evident that with increasing H2NCN content, the removal of glyphosate by Ag2NCN / BiVO4 exhibits a trend of first increasing and then decreasing, while PO4... 3- The selectivity also showed a trend of first increasing and then decreasing.
[0032] Example 8 Similar to Example 5, the irradiation time after adding AgNO3 solution was changed to 10 min, while other conditions remained unchanged, to obtain the Ag2NCN / BiVO4-10 catalyst. The product obtained after 90 min of reaction was tested using the method of Example 1, and the conclusions are as follows: Ag2NCN / BiVO4-10 achieved a glyphosate removal rate of 78.3%, generating AMPA at a concentration of 19.6 μmol / L with a selectivity of 25.0%; PO4 was also generated. 3- The content was 39.5 μmol / L, and the selectivity was 50.4%.
[0033] Example 9 Similar to Example 5, the irradiation time after adding AgNO3 solution was changed to 30 min, while other conditions remained unchanged, to obtain the Ag2NCN / BiVO4-30 catalyst. The product obtained after 90 min of reaction was tested using the method described in Example 1, and the conclusions are as follows: Ag2NCN / BiVO4-30 achieved a glyphosate removal rate of 95.6%, generating AMPA at a concentration of 44.6 μmol / L with a selectivity of 46.6%; PO4 was also generated. 3- The content was 49.8 μmol / L, and the selectivity was 52.1%.
[0034] Example 10 Similar to Example 5, the irradiation time after adding AgNO3 solution was changed to 90 min, while other conditions remained unchanged, to obtain the Ag2NCN / BiVO4-90 catalyst. The product obtained after 90 min of reaction was tested using the method described in Example 1, and the conclusions are as follows: Ag2NCN / BiVO4-90 achieved a glyphosate removal rate of 94.3%, generating AMPA at a concentration of 44.0 μmol / L with a selectivity of 45.3%; PO4 was also generated. 3- The content was 47.1 μmol / L, and the selectivity was 49.9%.
[0035] It is evident that the particle size of Ag on BiVO4 changes with increasing irradiation time, and the removal of glyphosate by Ag2NCN / BiVO4 shows a trend of first increasing and then decreasing, while PO4... 3- The selectivity also showed a trend of first increasing and then decreasing.
[0036] Example 11 Same as Example 6, but with the glyphosate concentration changed to 50 μmol / L, while other conditions remained unchanged. The product obtained after a reaction of 90 min was analyzed using the method described in Example 1, and the conclusions are as follows: The removal rate of glyphosate was 100.0% after 90 min, with AMPA concentration of 13.25 μmol / L and selectivity of 26.5%; PO4 was generated. 3- The content was 36.1 μmol / L, and the selectivity was 72.0%.
[0037] Example 12 Same as Example 6, but with the glyphosate concentration changed to 150 μmol / L, while other conditions remained unchanged. The product obtained after a reaction of 90 min was analyzed using the method described in Example 1, and the conclusions are as follows: The removal rate of glyphosate after 90 min was 96.1%, the concentration of AMPA generated was 41.7 μmol / L, and the selectivity was 28.9%; PO4 was generated. 3- The content was 104.9 μmol / L, and the selectivity was 72.8%.
[0038] It is evident that the removal efficiency of glyphosate does not change significantly with increasing glyphosate concentration, and the accumulation of AMPA is related to the glyphosate concentration.
[0039] Example 13 Same as Example 6, but with the reaction time changed to 10 min, while other conditions remained unchanged. The product obtained after 10 min of reaction was tested using the method described in Example 1, and the conclusions are as follows: The removal rate of glyphosate after 10 min was 30.9%, the concentration of AMPA generated was 19.8 μmol / L, and the selectivity was 64.1%; PO4 was generated. 3- The content was 3.34 μmol / L, and the selectivity was 10.8%.
[0040] Example 14 Same as Example 6, but with the reaction time changed to 20 min, while other conditions remained unchanged. The product obtained after 20 min of reaction was tested using the method described in Example 1, and the conclusions are as follows: The removal rate of glyphosate after 20 min was 90.0%, the concentration of AMPA generated was 29.3 μmol / L, and the selectivity was 32.5%; PO4 was generated. 3- The content was 10.3 μmol / L, and the selectivity was 11.4%.
[0041] Example 15 Same as Example 6, but with the reaction time changed to 30 min, while other conditions remained unchanged. The product obtained after 30 min of reaction was tested using the method described in Example 1, and the conclusions are as follows: The removal rate of glyphosate after 30 min was 96.2%, the concentration of AMPA generated was 31.9 μmol / L, and the selectivity was 33.2%; PO4 was generated. 3- The content was 17.3 μmol / L, and the selectivity was 18.0%.
[0042] Example 16 Same as Example 6, but with the reaction time changed to 60 min, while other conditions remained unchanged. The product obtained after 60 min of reaction was tested using the method described in Example 1, and the conclusions are as follows: The removal rate of glyphosate was 100.0% after 60 min, with AMPA concentration of 8.28 μmol / L and selectivity of 8.28%; PO4 was generated. 3- The content was 37.3 μmol / L, and the selectivity was 37.3%.
[0043] It is evident that the degradation of glyphosate gradually increases with the increase of photocatalytic reaction time, achieving complete removal of glyphosate within 60 min, and complete oxidation of AMPA by 90 min, generating a large amount of PO4. 3- .
[0044] In summary, during the preparation of the Ag₂NCN / BiVO₄ photocatalyst, the optimal addition amount of H₂NCN solution was 280 μL, the molar ratio of Ag to NCN was maintained at 1:2, and the optimal irradiation time after adding AgNO₃ was 60 min. The visible light irradiation time during the reaction was 90 min, and the optimal dosage of glyphosate was 100 μmol / L.
[0045] Comparative Example 1 Similar to Example 6, without the addition of H2NCN and AgNO3, using only 15 mg BiVO4 as a catalyst, the removal rate of glyphosate was 24.6%, the concentration of AMPA generated was 8.03 μmol / L, and the selectivity was 32.6%; PO4 was not detected in the solution. 3- .
[0046] Comparative Example 2 Similar to Example 6, without the addition of BiVO4, using only 15 mg Ag2NCN as a catalyst, the removal rate of glyphosate was 27.9%, the concentration of AMPA generated was 11.4 μmol / L, and the selectivity was 40.9%; PO4 was not detected in the solution. 3- .
[0047] It is evident that Ag2NCN and BiVO4 alone have limited ability to degrade glyphosate, but their combined action enables highly efficient degradation of glyphosate while simultaneously generating PO4 with resource recycling value. 3- .
Claims
1. A method for preparing a metal carbodiimide / bismuth vanadate composite photocatalyst, characterized in that, Includes the following steps: Bismuth vanadate, carbodiimide source, and silver source are mixed in a polar solvent and reacted under light irradiation to generate a metal carbodiimide / bismuth vanadate composite photocatalyst.
2. The preparation method according to claim 1, characterized in that, The carbodiimide source is cyanamide (H2NCN), the silver source is silver nitrate (AgNO3), the polar solvent is water, and the illumination condition is visible light irradiation; preferably, the wavelength of the visible light is 420 nm, the reaction is carried out at room temperature, and an inert gas is introduced for protection during the reaction; preferably, the inert gas is nitrogen.
3. The preparation method according to claim 2, characterized in that, The silver ions Ag in the silver source + With the carbodiimide ion [NCN] in the carbodiimide source 2- The molar ratio of the substances is 1:0.1 to 1:5; preferably 1:0.5 to 1:2; more preferably 1:
1.
4. The preparation method according to claim 3, characterized in that, Before adding the silver source, the mixture of bismuth vanadate, carbodiimide source and polar solvent is pre-illuminated for 5 to 10 minutes. After adding the silver source, the illumination time is continued for 10 to 90 minutes. Preferably, the illumination time after adding the silver source is 60 minutes.
5. A metal carbodiimide / bismuth vanadate composite photocatalyst prepared by the preparation method according to any one of claims 1-4.
6. The metal carbodiimide / bismuth vanadate composite photocatalyst according to claim 5, characterized in that, In the catalyst, silver carbodiimide Ag2NCN is supported on the surface of bismuth vanadate.
7. The application of the metal carbodiimide / bismuth vanadate composite photocatalyst according to claim 5 or 6 in the photocatalytic degradation of organophosphorus compounds.
8. The application according to claim 7, characterized in that, The organophosphorus compound is glyphosate.
9. The application according to claim 8, characterized in that, The aforementioned metal carbodiimide / bismuth vanadate composite photocatalyst was placed in wastewater containing glyphosate and subjected to photocatalytic degradation under visible light irradiation to degrade glyphosate and convert it into phosphate ions (PO4) with resource recovery value. 3- The concentration of glyphosate in the wastewater is 50–150 μmol / L, preferably 100 μmol / L; the irradiation time with visible light is 10–90 min, preferably 90 min.
10. A method for photocatalytic degradation of glyphosate and simultaneous recovery of phosphorus resources, characterized in that, include: The metal carbodiimide / bismuth vanadate composite photocatalyst of claim 5 or 6 is mixed with glyphosate-containing wastewater and reacted under visible light irradiation to obtain a reaction solution containing phosphate ions. The reaction is carried out at room temperature and normal pressure. The visible light wavelength is 420 nm.