Porphyrin-based iron metal organic framework catalyst for improving photoresponsiveness

Abstract

The invention relates to a porphyrin-based iron metal organic framework (Fe-TCPP) catalyst for improving photoresponsiveness, which is characterized in that the Fe-TCPP nano catalyst is prepared by using an iron source and meso-tetra (4-carboxyphenyl) porphin (TCPP) as precursors through a simple solvothermal method, assisting coordination by virtue of polyvinylpyrrolidone (PVP), performing sealed reaction after ultrasonic dispersion, and preparing the Fe-TCPP nano catalyst. A purple suspension is obtained. And centrifuging, washing and drying to obtain the nano rod-shaped Fe-TCPP metal organic framework material. The Fe-TCPP catalyst prepared by the preparation method disclosed by the invention has a regular crystal structure and good dispersity, and can be stably coordinated to form a Fe-O cluster structure. The effective introduction of the TCPP enhances the charge transfer (LCCT) capability from the ligand to the metal cluster, effectively promotes the Fe (III) / Fe (II) circulation, and improves the photocatalysis-ozonation catalytic efficiency. The catalyst has the advantages of high thermal stability, less metal ion dissolution, good cycle performance and the like, and has wide application potential in the field of water treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysis-ozonation, and in particular to a method for preparing a porphyrin-based iron metal organic framework (Fe-TCPP) catalyst for improving light responsiveness. Background Art

[0002] Pharmaceutical contaminants, emerging organic pollutants, are widely present in surface and groundwater, significantly impacting surface water quality and aquatic life, and are one of the main culprits contributing to the decline in aquatic biomass. Among these, pharmaceutical contaminants, such as nonsteroidal anti-inflammatory drugs (NSAIDs), accumulate in the food chain. Because pharmaceutical contaminants are difficult to metabolize in organisms, they gradually accumulate in the food chain, leading to potential environmental pollution and ecological risks. Among numerous water treatment technologies, photocatalysis has become a research hotspot due to its advantages of simple equipment, wide range of treatment options, high efficiency, and environmental friendliness. Over the past decade, ozone-based advanced oxidation technologies have attracted significant interest due to their high efficiency, simple operation, wide pH adaptability, and absence of toxic residues in post-treated water. Among these, photocatalytic ozone oxidation (PCO) can more effectively degrade organic pollutants under light irradiation, making it particularly attractive for the degradation of refractory pharmaceuticals. Key to PCO is the development of catalysts. Iron-based metal-organic frameworks (Fe-MOFs) have attracted considerable attention among ozone-based AOPs due to their low cost, non-toxicity, periodic pore structure, abundant Lewis acid sites, and tunable light absorption. However, traditional Fe-MOF materials (such as MIL-100(Fe)) use organic compounds such as trimesic acid and terephthalic acid as ligands, but these ligands have weak photoresponsiveness. Insufficient photosensitivity leads to insufficient light absorption and utilization during the PCO process, thereby limiting the performance of the photocatalytic part of the catalyst in PCO. Therefore, it is imperative to improve the photoresponsiveness of MOF materials by changing the ligands, thereby improving the degradation efficiency of pollutants.

[0003] To this end, porphyrin-based ligands are widely used to improve the photoresponsiveness of materials due to their strong ligand-to-cluster charge transfer (LCCT) excitation and wider light absorption range. By constructing iron-based MOF materials with porphyrin ligands, efficient photoinduced charge separation and transfer can be achieved, thereby significantly accelerating the Fe(III) / Fe(II) conversion process, thereby generating a large number of reactive oxygen species to participate in the degradation of pollutants. The research of Li et al. showed that by introducing porphyrin-based ligands to prepare the structure of iron-based MOF, its activity in the photo-Fenton reaction can be greatly improved. The material showed excellent performance in the degradation of the antibiotic ciprofloxacin (CIP), which further demonstrated the importance of structural optimization in improving catalyst performance (Li, WQ, Wang, YX, et al., Applied Catalysis B: Environmental 302 2022, 120882) Summary of the Invention

[0004] A preparation technology for a porphyrin-based iron metal organic framework catalyst for improving light responsiveness is characterized in that: the catalyst is prepared by dissolving Fe(NO3)3·9H2O and PVP in a mixed solution of DMF and anhydrous ethanol to form a liquid A; TCPP is dissolved in a mixed solution of DMF and anhydrous ethanol to form a liquid B, liquid A and liquid B are separately ultrasonicated and then mixed and further ultrasonicated, the ultrasonicated mixed solution is subjected to a solvothermal reaction in a polytetrafluoroethylene liner, and the suspension is finally washed, centrifuged and vacuum dried to obtain the porphyrin-based Fe-TCPP metal organic framework catalyst.

[0005] Furthermore, the above process includes the following specific steps:

[0006] First, prepare dispersion A: add 1-5 mg Fe(NO3)3·9H2O, 2.5-12 mg PVP, 8-15 mL DMF and 2.5-5 mL ethanol into a beaker, mix, and ultrasonicate at room temperature for 0.5-2 h to obtain dispersion A;

[0007] Further, dispersion B was prepared by adding 3-6 mg of TCPP to 2.5-5 mL of DMF and 0.5-1.5 mL of ethanol, mixing, and ultrasonicating at room temperature for 0.5-2 h to obtain dispersion B;

[0008] Furthermore, after mixing solution A and solution B, ultrasonic treatment was continued for 0.5-2h;

[0009] Further, the obtained mixed solution was transferred to a polytetrafluoroethylene-lined high-pressure stainless steel reactor and subjected to solvothermal reaction at 80-100° C. for 24 hours;

[0010] Furthermore, the solid matter after the solvothermal reaction is washed with DMF and deionized water 3-6 times in sequence, and centrifuged at a speed of 8000-10000 r / min to obtain a catalyst;

[0011] Finally, the washed solid product was placed in a vacuum oven at 50-80° C. and dried overnight to obtain the Fe-TCPP catalyst.

[0012] This study uses a one-step solvothermal method to prepare a well-structured, well-dispersed nanorod-shaped Fe-TCPP catalyst. Composed of Fe and TCPP ligands, the catalyst exhibits a ligand-to-metal cluster charge transfer (LCCT) mechanism, broadening the light absorption range and effectively promoting the Fe(III) / Fe(II) conversion process, enhancing the production of reactive oxygen species, and thus significantly improving photocatalytic and ozone oxidation performance. Furthermore, the material exhibits excellent thermal stability and recyclability, making it suitable for the efficient degradation of organic pollutants driven by visible light, and has broad application prospects.

[0013] Most specifically, a method for preparing a porphyrin-based iron metal organic framework catalyst for improving light responsiveness is characterized by the following steps:

[0014] First, 9 mL of DMF and 3 mL of ethanol were added to a beaker, followed by the addition of 4.0 mg of Fe(NO₃)₃·9H₂O and 10 mg of PVP. The mixture was sonicated at room temperature for 0.5 h to form stock solution A. Simultaneously, 4.4 mg of TCPP was dissolved in a mixture of 3 mL of DMF and 1 mL of ethanol and sonicated for 0.5 h to form stock solution B. Stock solutions A and B were then mixed and sonicated for another 0.5 h to homogenize the mixture. After sonication, the mixture was solvothermally reacted in a polytetrafluoroethylene-lined autoclave at 90°C for 24 h. The resulting solid product was washed three times with DMF and deionized water, followed by centrifugation at 9000 rpm to obtain the catalyst. Finally, the washed solid was dried in a vacuum oven at 60°C overnight to yield a highly photoresponsive porphyrin-based Fe-TCPP catalyst.

[0015] The present invention has the following technical effects:

[0016] The preparation method for a porphyrin-based iron metal-organic framework (Fe-TCPP) catalyst developed by this invention utilizes a one-step solvothermal reaction, resulting in a simple process and a product with a regular morphology and stable structure. In the resulting catalyst, a ligand-to-cluster charge transfer (LCCT) mechanism is formed between Fe and TCPP, broadening the catalyst's light absorption range. This structure accelerates Fe(III) / Fe(II) conversion under visible light, effectively increasing the generation efficiency of reactive oxygen species and demonstrating excellent photocatalytic and ozone oxidation catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : SEM image of Fe-TCPP.

[0018] Figure 2 : Optical absorption and energy band diagram of Fe-TCPP and MIL-100(Fe).

[0019] (a) UV-visible absorption diagram; (b) energy band diagram

[0020] Figure 3 : Comparison of photocatalytic-ozone oxidation degradation performance of Fe-TCPP and MIL-100(Fe).

[0021] Figure 4 : Degradation efficiency of Fe-TCPP under different conditions. DETAILED DESCRIPTION

[0022] Example 1

[0023] A method for preparing a Fe-TCPP nanorod catalyst is carried out according to the following steps:

[0024] First, 12 mL of DMF and 4 mL of ethanol were added to a beaker, followed by the addition of 3 mg of Fe(NO₃)₃·9H₂O and 7.5 mg of PVP. The mixture was sonicated at room temperature for 0.5 h to form stock solution A. Simultaneously, 5 mg of TCPP was dissolved in a mixture of 4 mL of DMF and 1 mL of ethanol and sonicated for 1.5 h to form stock solution B. Stock solutions A and B were then mixed and sonicated for another 1.5 h to homogenize the mixture. After sonication, the mixture was solvothermally reacted in a polytetrafluoroethylene-lined autoclave at 80°C for 24 h. The resulting solid product was washed four times with DMF and deionized water, followed by centrifugation at 9000 rpm to obtain the catalyst. Finally, the washed solid was dried in a vacuum oven at 70°C overnight to yield a highly photoresponsive porphyrin-based Fe-TCPP catalyst.

[0025] Example 2

[0026] A method for preparing a Fe-TCPP nanorod catalyst is carried out according to the following steps:

[0027] First, 8 mL of DMF and 2.5 mL of ethanol were placed in a beaker, to which 1.0 mg of Fe(NO₃)₃·9H₂O and 3 mg of PVP were added sequentially. The mixture was sonicated at room temperature for 1 hour to form stock solution A. Simultaneously, 3.0 mg of TCPP was dissolved in a mixture of 2 mL of DMF and 0.5 mL of ethanol and sonicated for 1 hour to form stock solution B. Stock solutions A and B were then mixed and sonicated for another hour to homogenize the mixture. After sonication, the mixture was solvothermally reacted in a polytetrafluoroethylene-lined autoclave at 80°C for 24 hours. The resulting solid product was washed three times with DMF and deionized water, followed by centrifugation at 8000 rpm to obtain the catalyst. Finally, the washed solid was dried in a vacuum oven at 50°C overnight to yield a highly photoresponsive porphyrin-based Fe-TCPP catalyst.

[0028] Example 3

[0029] A method for preparing a Fe-TCPP nanorod catalyst is carried out according to the following steps:

[0030] First, 15 mL of DMF and 5 mL of ethanol were added to a beaker, followed by the addition of 5 mg of Fe(NO₃)₃·9H₂O and 12 mg of PVP. The mixture was sonicated at room temperature for 0.5 h to form stock solution A. Simultaneously, 6.0 mg of TCPP was dissolved in a mixture of 5 mL of DMF and 1.5 mL of ethanol and sonicated for 2 h to form stock solution B. Stock solutions A and B were then mixed and sonicated for another 2 h to homogenize the mixture. After sonication, the mixture was solvothermally reacted in a polytetrafluoroethylene-lined autoclave at 100°C for 24 h. The resulting solid product was washed six times with DMF and deionized water, followed by centrifugation at 10,000 rpm to obtain the catalyst. Finally, the washed solid was dried in a vacuum oven at 80°C overnight to yield a highly photoresponsive porphyrin-based Fe-TCPP catalyst.

[0031] From the attached Figure 1 It can be seen that Fe(TCPP)-MOF has a nanorod-like structure, which is conducive to the transmission of electrons in the structure and thus improves the degradation efficiency of pollutants.

[0032] Compare with Figure 2Comparing MIL-100(Fe) and Fe-TCPP in the accompanying figure, we can see that Fe-TCPP has a wider light absorption range than MIL-100(Fe), enhancing its photoresponsiveness. The light absorption characteristics and band gaps of Fe(TCPP)-MOF and MIL-100(Fe) are: the band gap of Fe(TCPP)-MOF is approximately 2.11 eV, and the band gap of MIL-100(Fe) is approximately 2.73 eV.

[0033] Attachment Figure 3 It can be seen that the Fe-TCPP photocatalytic-ozonation degradation efficiency is significantly higher than the catalytic ozone degradation efficiency, highlighting the synergistic effect of light and ozone catalytic oxidation.

[0034] Attachment Figure 4 It can be seen that under the conditions of photocatalysis-ozone oxidation, the degradation efficiency and degradation rate of Fe-TCPP are faster than those of MIL-100(Fe), indicating that the improvement of light responsiveness promotes the valence cycle of Fe, thereby promoting the generation of reactive oxygen species and improving the degradation efficiency of pollutants.

[0035] Obviously, the above description is merely an embodiment of the present invention. It should be noted that those skilled in the art may make a number of modifications and improvements without departing from the structure of the present invention, and these modifications and improvements should also be considered as the scope of protection of the present invention, and these modifications and improvements will not affect the effectiveness of the implementation of the present invention and the practicality of the patent.

Claims

1. A porphyrin-based iron metal organic framework (Fe-TCPP) catalyst for improving photoresponsiveness, characterized in that: The Fe-TCPP nanorod catalyst was prepared using a simple surfactant-assisted solvothermal method. Dispersion A, containing ferric nitrate nonahydrate (Fe(NO3)3·9H2O), polyvinylpyrrolidone (PVP), N,N-dimethylformamide (DMF), and ethanol, was sonicated for several minutes. Dispersion B, containing meso-tetrakis(4-carboxyphenyl)porphine (TCPP), DMF, and ethanol, was then sonicated for several minutes. Next, dispersions A and B were mixed and sonicated again, and the mixture was then placed in a polytetrafluoroethylene-lined autoclave. Finally, the resulting solid material was washed sequentially with DMF and deionized water and dried in a vacuum oven overnight to obtain the catalyst.

2. A porphyrin-based iron metal organic framework catalyst for improving photoresponsiveness according to claim 1, characterized in that: Solution A is prepared by dissolving Fe(NO3)3·9H2O and PVP in a mixture of DMF and ethanol. The amount of DMF used is 8-15 mL, the amount of ethanol used is 2.5-5 mL, the amount of Fe(NO3)3·9H2O added is 1-5 mg, and the amount of PVP added is 2.5-12 mg.

3. A porphyrin-based iron metal organic framework catalyst for improving photoresponsiveness according to claim 1, characterized in that: Solution B is prepared by dissolving TCPP in a mixture of DMF and ethanol. The required TCPP mass is 3-6 mg, the amount of DMF is 2.5-5 mL, and the amount of ethanol is 0.5-1.5 mL.

4. The porphyrin-based iron metal organic framework catalyst for improving photoresponsiveness according to claims 1-3, characterized in that: Liquid A and liquid B were ultrasonicated for 0.5-2 h respectively and then mixed, and then the AB mixed solution was ultrasonicated for another 0.5-2 h.

5. The porphyrin-based iron metal organic framework catalyst for improving photoresponsiveness according to claim 4, characterized in that: The sonicated solution was transferred to a polytetrafluoroethylene-lined reactor and subjected to solvothermal reaction at 80-100°C for 24 h.

6. A porphyrin-based iron metal organic framework catalyst for improving photoresponsiveness according to claim 5, characterized in that: After the solvothermal reaction, the solid matter is washed with DMF and deionized water for 3-6 times in sequence, and centrifuged at a speed of 8000-10000 r / min to obtain a catalyst.

7. A porphyrin-based iron metal organic framework catalyst for improving photoresponsiveness according to claim 6, characterized in that: The sample after centrifugation should be dried in a vacuum drying oven at 50-80°C overnight to obtain the desired catalyst.

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