A MOF-derived double-defect La 0.8 FeO 3-δ Preparation method and application thereof

Abstract

The present invention belongs to the field of semiconductor photocatalysis and Fenton-like technology, and specifically relates to a MOF-derived double-defect La 0.8 FeO 3‑δ Preparation method and application thereof: The present invention prepares La and O vacancy double defect La based on MOF derivatization method. 0.8 FeO 3‑δ The method mainly comprises the following steps: using ferric chloride hexahydrate and terephthalic acid as raw materials, a MOF material with terephthalic acid as a ligand is prepared by a solvent thermal method; reacting the prepared MOF material with lanthanum nitrate hexahydrate in an organic solvent, and calcining the reaction product to obtain MOF-derived double-defect La 0.8 FeO 3‑δ The antibiotic catalytic degradation test confirmed that the La prepared by the present invention 0.8 FeO 3‑δ It has strong anti-interference ability, high selectivity for organic matter, high catalytic degradation activity and cyclic stability, and has high application prospects in the field of catalytic degradation of organic pollutants such as antibiotics.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor photocatalysis and Fenton-like technology, and in particular relates to a MOF-derived double-defect La 0.8 FeO 3-δ Preparation method and application thereof. Background Art

[0002] Organic pollutants that contaminate water, the environment, and food are among the greatest threats to human health and the environment. Advanced oxidation processes (AOPs) such as Fenton, photocatalysis, and Fenton-like systems have attracted considerable attention due to their powerful oxidative abilities, but conventional methods struggle to effectively remove organic pollutants. Among them, Fenton-like systems based on peroxymonosulfate (PMS) are considered to have great potential for addressing the pollution problems of organic pollutants such as antibiotics. Heat, microwaves, ultraviolet light, ionizing radiation, and transition metal catalysts are currently the main methods for PMS activation. However, physical methods such as heat treatment, ultrasound, and ultraviolet light are unsuitable because they are highly dependent on a continuous energy supply and offer unsatisfactory economic benefits. Furthermore, secondary contamination caused by transition metal ions limits their application in the field of AOPs. Therefore, finding feasible solutions for peroxymonosulfate activation remains a research hotspot.

[0003] Photoactivation technology based on photocatalysts is considered a green method for activating PMS due to its outstanding characteristics of photoinitiation and environmental friendliness. Under visible light irradiation, photocatalysts can release photocarriers, promoting the decomposition of PMS and inducing the formation of reactive oxygen free radicals. Numerous studies have shown that structural defects such as oxygen vacancies, carbon vacancies, and sulfur vacancies play a significant role in the activation of PMS, especially in photocatalysts with defects.

[0004] Metal-organic frameworks (MOFs) are widely used in the field of catalysis due to their ultra-high specific surface area, highly ordered pore structure, and adjustable pore size and shape. The use of MOFs as sacrificial templates provides a promising approach for the preparation of metal oxides with complex compositions and diverse structures. Compared with other methods, metal oxides derived from MOF templates have the advantages of uniform size, hierarchical porosity, large surface area, and controllable composition. In order to further improve the catalytic activity of MOF-derived catalysts, it is necessary to optimize the structure and composition of the solid to resolve the inherent defects of the single metal site and expose more active sites for catalytic oxidation. Therefore, the preparation of defect-rich oxides is a huge challenge.

[0005] High-valent iron-oxygen species, as typical non-radical active species, exhibit high activity and stability in the photo-Fenton-like degradation of antibiotics due to their strong anti-interference ability, long lifetime (7-10 seconds), and high selectivity for organic matter. Currently, there is no precedent for utilizing A-site defects and oxygen vacancies to jointly accelerate the generation of high-valent iron species (Fe(IV)=O). Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention aims to provide a MOF-derived double-defect La 0.8 FeO 3-δ Preparation method and application thereof: The present invention is the first to prepare MOF-derived double-defect La with La vacancies and oxygen vacancies based on MOF derivatization method. 0.8 FeO 3-δ Its La vacancies and oxygen vacancies jointly promote the generation of high-valent iron-oxygen species (Fe(IV)=O), giving it strong anti-interference ability and high selectivity for organic matter, and showing high catalytic activity and cyclic stability in the Fenton-like photocatalytic degradation of organic pollutants such as antibiotics.

[0007] Based on the above purpose, the technical solution adopted by the present invention is as follows:

[0008] In the first aspect, the present invention provides a MOF-derived double-defect La 0.8 FeO 3-δ The preparation method comprises the following steps:

[0009] S1: Using ferric chloride hexahydrate and terephthalic acid as raw materials, an iron-based organic framework compound with terephthalic acid as ligand was prepared by solvothermal method, which was marked as MIL-88B.

[0010] S2: The MIL-88B prepared in step S1 is reacted with lanthanum nitrate hexahydrate in an organic solvent at 80°C to 90°C, and the reaction product is calcined to obtain MOF-derived double-defect La 0.8 FeO 3-δ .

[0011] Preferably, in step S1, the molar ratio of ferric chloride hexahydrate to terephthalic acid is 1:(0.8-1.2).

[0012] Preferably, in step S2, the mass ratio of MIL-88B to lanthanum nitrate hexahydrate is 1:(0.8-1.2).

[0013] Preferably, the organic solvent in step S2 is ethanol; and the calcination is to heat the reaction product of MIL-88B and lanthanum nitrate hexahydrate to 600° C. to 800° C. at a heating rate of 8 to 12° C. / min and calcine for 5 to 7 hours.

[0014] Preferably, the reaction in step S2 is to mix MIL-88B and lanthanum nitrate hexahydrate and disperse them in ethanol, and stir the mixture at 80° C. to 90° C. until the ethanol is completely evaporated, so that the MIL-88B and lanthanum nitrate hexahydrate react completely.

[0015] Preferably, the solvothermal method in step S1 comprises the following steps:

[0016] Ferric chloride hexahydrate and terephthalic acid are dissolved in N,N-dimethylformamide, reacted at 140°C to 150°C for 11 to 13 hours, and then cooled, washed and dried to obtain MIL-88B.

[0017] In the second aspect, the present invention provides a MOF-derived double-defect La prepared by the above method. 0.8 FeO 3-δ , La 0.8 FeO 3-δ It contains lanthanum (La) vacancies and oxygen (O) vacancies.

[0018] In the third aspect, the present invention claims the above MOF-derived double-defect La 0.8 FeO 3-δ Application in degradation of organic pollutants.

[0019] Preferably, the organic pollutants include antibiotics, organic dyes, pharmaceuticals, antiseptics and disinfectants, and industrial chemicals.

[0020] Preferably, the antibiotics include levofloxacin and tetracycline; the organic dye includes rhodamine B; the drug includes ibuprofen; the antiseptic disinfectant includes phenol; and the industrial chemical includes bisphenol A.

[0021] The results of the experiment showed that the MOF-derived double-defect La prepared by the present invention 0.8 FeO 3-δ It has a relatively better degradation effect on electron-rich pollutants such as tetracycline (TC) and rhodamine B (RhB).

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This paper first prepared double-defect La with La vacancies and oxygen vacancies based on MOF derivatization method. 0.8 FeO 3-δ It has strong anti-interference ability and high selectivity for organic matter in the catalytic degradation of organic pollutants, especially electron-rich pollutants. It also has high catalytic degradation activity and cyclic stability, and has high application prospects in the field of catalytic degradation of organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The XRD patterns of the products of Example 1, Comparative Example 1 and Comparative Example 2 are shown;

[0025] Figure 2 The following are SEM images of the products of Example 1, Comparative Example 1 and Comparative Example 2;

[0026] Figure 3 This is the HAADF-STEM image of the product in Example 1;

[0027] Figure 4 1 is the EPR diagram of the product of Example 1 and Comparative Example 2;

[0028] Figure 5 This is the photo-Fenton-like catalytic degradation curve of levofloxacin by the products of Examples 1 to 3;

[0029] Figure 6 The photo-Fenton-like catalytic degradation curves of levofloxacin by the products of Example 1, Comparative Example 1 and Comparative Example 2 are shown;

[0030] Figure 7 This is a bar graph of the corresponding ion leaching concentrations after the products of Example 1, Comparative Example 1 and Comparative Example 2 catalyzed degradation of antibiotic LVX;

[0031] Figure 8 The graph shows the PMSO consumption / PMSO2 production and PMSO2 production rate of the products of Example 1 and Comparative Example 2 in the photo-Fenton-like reaction;

[0032] Figure 9 This is the photo-Fenton catalytic degradation curve of the product of Example 1 on antibiotics under the influence of 20 mM different ions and 5 mg / L humic acid;

[0033] Figure 10 Graph showing the relationship between the degradation rate k of different pollutants (tetracycline: TC, rhodamine B: RhB, bisphenol A: BPA, phenol: PE, ibuprofen: IBU) by the photo-Fenton degradation method of the product of Example 1 and the ionization potential of the pollutants;

[0034] Figure 11 This is a cycle test diagram of the photo-Fenton degradation of antibiotics by the products of Example 1, Comparative Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0035] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be further described below with reference to specific examples. Those skilled in the art will appreciate that the specific examples described herein are intended only to illustrate the present invention and are not intended to limit the present invention. The experimental methods used in the examples are conventional methods unless otherwise specified; the materials and reagents used are commercially available unless otherwise specified.

[0036] Example 1

[0037] This embodiment provides a MOF-derived double-defect La 0.8 FeO 3-δ -600 preparation method, comprising the following steps:

[0038] (1) 0.622 g (2.3 mmol) of FeCl3·6H2O and 0.382 g (2.3 mmol) of terephthalic acid (H2BDC) were dissolved in 50 mL of N,N-dimethylformamide (DMF) and magnetically stirred for 15 min. The mixture was then transferred to a polytetrafluoroethylene-lined autoclave and heated at 145 °C for 12 h. After cooling to room temperature, the mixture was washed with water and ethanol several times and dried at 70 °C for 12 h to obtain MIL-88B.

[0039] (2) Weigh 0.10 g of the prepared MIL-88B and 0.10 g of La(NO3)3·6H2O and disperse them in 100 mL of ethanol. Stir the mixture in an oil bath at 80 °C until the ethanol is completely evaporated.

[0040] (3) After the reaction is completed, the reaction product is heated to 600 °C at a heating rate of 10 °C / min, calcined in air for 6 h, and then cooled to room temperature to obtain MOF-derived double-defect La 0.8 FeO 3-δ -600, recorded as Md-La 0.8 FeO 3-δ -600.

[0041] Example 2

[0042] This embodiment provides a MOF-derived double-defect La 0.8 FeO 3-δ -700 preparation method, comprising the following steps:

[0043] (1) 0.622 g of FeCl3·6H2O (2.3 mmol) and 0.382 g (2.3 mmol) of terephthalic acid (H2BDC) were dissolved in 50 mL of N,N-dimethylformamide (DMF) and magnetically stirred for 15 min. The mixture was then transferred to a polytetrafluoroethylene-lined autoclave and heated at 145 °C for 12 h. After cooling to room temperature, the mixture was washed with water and ethanol several times and dried at 70 °C for 12 h to obtain MIL-88B.

[0044] (2) Weigh 0.10 g of the prepared MIL-88B and 0.10 g of La(NO3)3·6H2O and disperse them in 100 mL of ethanol. Stir the mixture in an oil bath at 80 °C until the ethanol is completely evaporated.

[0045] (3) After the reaction is completed, the reaction product is heated to 700 °C at a heating rate of 10 °C / min, calcined in air for 6 h, and then cooled to room temperature to obtain MOF-derived double-defect La 0.8 FeO 3-δ -700, recorded as Md-La 0.8 FeO 3-δ -700.

[0046] Example 3

[0047] This embodiment provides a MOF-derived double-defect La 0.8 FeO 3-δ -800 preparation method, comprising the following steps:

[0048] (1) 0.622 g of FeCl3·6H2O (2.3 mmol) and 0.382 g (2.3 mmol) of terephthalic acid (H2BDC) were dissolved in 50 mL of N,N-dimethylformamide (DMF) and magnetically stirred for 15 min. The mixture was then transferred to a polytetrafluoroethylene-lined autoclave and heated at 145 °C for 12 h. After cooling to room temperature, the mixture was washed with water and ethanol several times and dried at 70 °C for 12 h to obtain MIL-88B.

[0049] (2) Weigh 0.10 g of the prepared MIL-88B and 0.10 g of La(NO3)3·6H2O and disperse them in 100 mL of ethanol. Stir the mixture in an oil bath at 80 °C until the ethanol is completely evaporated.

[0050] (3) After the reaction is completed, the reaction product is heated to 800 °C at a heating rate of 10 °C / min, calcined in air for 6 h, and then cooled to room temperature to obtain MOF-derived double-defect La 0.8 FeO 3-δ -800, recorded as Md-La 0.8 FeO 3-δ -800.

[0051] Comparative Example 1

[0052] 0.622 g of FeCl3·6H2O and 0.382 g of terephthalic acid (H2BDC) were dissolved in 50 mL of DMF and magnetically stirred for 15 min. The mixture was then transferred to a polytetrafluoroethylene-lined high-pressure reactor and heated at 145°C for 12 h. After cooling to room temperature, the mixture was washed with water and ethanol several times and dried at 70°C for 12 h to obtain MIL-88B.

[0053] Comparative Example 2

[0054] 3 mmol La(NO3)3·6H2O, 3 mmol FeCl3·6H2O, and 1.52 g citric acid were dissolved in 20 mL ethanol. The mixture was heated to 80°C and gently stirred until a gel formed. The resulting solid was ground and then calcined in a muffle furnace at a heating rate of 10°C / min to 600°C for 6 h. Finally, the resulting powder was centrifuged and washed several times. The resulting product was recorded as S-LaFeO 3-δ .

[0055] The XRD patterns of the products obtained in Example 1, Comparative Example 1 and Comparative Example 2 are as follows: Figure 1 As shown by Figure 1 It can be seen that Md-La 0.8 FeO 3-δ -600 and S-LaFeO 3-δ All of them correspond to LaFeO3 with a standard card of 74-2203. 3+ The presence of defects, Md-La 0.8 FeO 3-δ The characteristic peaks and surface crystallinity are reduced.

[0056] The SEM images of the products obtained in Example 1, Comparative Example 1 and Comparative Example 2 are as follows: Figure 2 As shown in the figure, (a), (b), and (c) represent Md-La 0.8 FeO 3-δ -600, MIL-88B, S-LaFeO 3-δ SEM image of Figure 2 It can be seen that MIL-88B has an octahedral structure (b), S-LaFeO 3-δ It is in irregular block shape (c), and the Md-La formed after calcination is derived 0.8 FeO 3-δ -600 presents many uniform small particles (a), indicating that the introduction of cation vacancies at the A site inhibits the growth of grain size.

[0057] Md-La prepared in Example 1 0.8 FeO 3-δ -600 HAADF-STEM image as shown Figure 3 As shown, many dark spots can be seen, indicating that there are many cationic La vacancies on the surface of the product.

[0058] Md-La prepared in Example 1 0.8 FeO 3-δ -600 and S-LaFeO prepared in Comparative Example 2 3-δ The EPR diagram is as follows Figure 4 As shown in the figure, it can be seen that there is a pair of symmetrical peaks at g = 2.003, confirming the Md-La 0.8FeO 3-δ and S-LaFeO 3-δ Both materials have oxygen vacancies, and Md-La 0.8 FeO 3-δ -600 contains more oxygen vacancies.

[0059] The degradation performance of the products of Examples 1 to 3, Comparative Example 1 and Comparative Example 2 on antibiotics was analyzed, and the specific test method is as follows:

[0060] 10 mg of catalyst was added to a 50 mL, 50 mg / L levofloxacin (LVX) solution and stirred in the dark for 40 minutes to reach adsorption-desorption equilibrium. 0.4 mM PMS was then added to the beaker, and a 300 W Xe lamp with a >420 nm filter was used as the light source to irradiate the sample in the beaker. Every 10 minutes, 0.2 mL of aqueous solution was extracted using a syringe with a 0.45 μm filter, and an equal volume of Na2S2O3 was immediately added to terminate the reaction. The concentration of the remaining LVX was then analyzed using high-performance liquid chromatography (HPLC, Shimadzu 2030C). After the reaction, the catalyst was centrifuged and washed, and then subjected to a cyclic stability test.

[0061] The catalytic degradation curves of antibiotic LVX in Examples 1 to 3 are as follows: Figure 5 As shown by Figure 5 It can be seen that compared with Examples 2 and 3, the Md-La prepared in Example 1 0.8 FeO 3-δ -600 showed better catalytic degradation efficiency for antibiotic LVX.

[0062] The catalytic degradation curves of antibiotic LVX in Example 1, Comparative Example 1 and Comparative Example 2 are as follows: Figure 6 As shown by Figure 6 It can be seen that compared with Comparative Examples 1 and 2, the Md-La prepared in Example 1 0.8 FeO 3-δ -600 showed better catalytic degradation efficiency for antibiotic LVX.

[0063] Example 1, Comparative Example 1 and Comparative Example 2 show the ion leaching concentration after catalytic degradation of antibiotic LVX. Figure 7 As shown by Figure 7 It can be seen that compared with Comparative Examples 1 and 2, the Md-La prepared in Example 1 0.8 FeO 3-δ After the degradation of antibiotic LVX by -600, the leaching of metal Fe and La in the degradation solution was the least.

[0064] Md-La in Example 1 0.8 FeO3-δ -600 and S-LaFeO in Comparative Example 2 3-δ In the photo-Fenton reaction, the ratio of PMSO consumption to PMSO2 production, as well as the PMSO2 production rate, are shown in Table 1. Figure 8 As shown, it can be seen that in Md-La 0.8 FeO 3-δ In the -600 / PMS / Vis system, PMSO was rapidly oxidized to PMSO2. This result indicates that Fe(IV)=O in Md-La 0.8 FeO 3-δ -600 system and dominates the oxidation of PMSO, which also explains the 0.8 FeO 3-δ -600 has higher activity and stability.

[0065] Md-La in Example 1 0.8 FeO 3-δ -600 at 20 mM different ions such as Cl - 、HCO3 - 、H2PO4 - , and the activity of photo-Fenton-like degradation of antibiotics under the influence of 5 mg / L humic acid (HA), e.g. Figure 9 As shown, in addition to high H2PO4 - Outside the environment, Md-La 0.8 FeO 3-δ -600 in high Cl - 、HCO3 - , HA and other environments have strong anti-interference performance.

[0066] Md-La in Example 1 0.8 FeO 3-δ The relationship between the degradation rate (k) of different pollutants by -600 photo-Fenton degradation and the ionization potential of pollutants is as follows: Figure 10 As shown. The ionization potential (IP) is closely related to the electron donating / withdrawing ability of the substituent. Aromatic compounds with electron donating groups (such as hydroxyl and amino) usually have lower IP values ​​and are more easily oxidized by Fe(VI) and other non-radical reaction substances, while aromatic compounds with electron withdrawing groups (such as nitro and carboxyl) show obvious opposite properties. As can be seen from the figure, the ionization potential of the pollutant is negatively correlated with the degradation rate k value, which further proves that Md-La 0.8 FeO 3-δ The -600 type photo-Fenton degradation system is a degradation process dominated by high-valent iron, and has a relatively better degradation effect on electron-rich pollutants such as TC and RhB.

[0067] Md-La in Example 1 0.8 FeO3-δ -600, MIL-88B in Comparative Example 1, and S-LaFeO in Comparative Example 2 3-δ The results of the photo-Fenton-like cycle test on antibiotic degradation are as follows: Figure 11 As shown. It can be seen that compared with MIL-88B and S-LaFeO 3-δ , Md-La 0.8 FeO 3-δ -600 has good reusability and cycle stability.

Claims

1. A MOF-derived double-defect La 0.8 FeO 3-δ The preparation method is characterized in that The steps include: S1: Using ferric chloride hexahydrate and terephthalic acid as raw materials, an iron-based organic framework compound with terephthalic acid as ligand was prepared by solvothermal method, which was marked as MIL-88B. S2: The MIL-88B prepared in step S1 is reacted with lanthanum nitrate hexahydrate in an organic solvent at 80°C to 90°C, and the reaction product is calcined in air to obtain MOF-derived double-defect La 0.8 FeO 3-δ .

2. MOF-derived double-defect La according to claim 1 0.8 FeO 3-δ The preparation method is characterized in that The molar ratio of ferric chloride hexahydrate to terephthalic acid in step S1 is 1:(0.8-1.2).

3. MOF-derived double-defect La according to claim 1 0.8 FeO 3-δ The preparation method is characterized in that The mass ratio of MIL-88B to lanthanum nitrate hexahydrate in step S2 is 1:(0.8-1.2).

4. MOF-derived double-defect La according to claim 1 0.8 FeO 3-δ The preparation method is characterized in that The organic solvent in step S2 is ethanol; the calcination is to heat the reaction product of MIL-88B and lanthanum nitrate hexahydrate to 600° C. to 800° C. at a heating rate of 8 to 12° C. / min and calcine for 5 to 7 hours.

5. MOF-derived double-defect La according to claim 1 0.8 FeO 3-δ The preparation method is characterized in that The reaction in step S2 is to mix MIL-88B and lanthanum nitrate hexahydrate and disperse them in ethanol, and stir the mixture at 80° C. to 90° C. until the ethanol is completely evaporated.

6. MOF-derived double-defect La according to claim 1 0.8 FeO 3-δ The preparation method is characterized in that The solvothermal method in step S1 comprises the following steps: Ferric chloride hexahydrate and terephthalic acid are reacted in N,N-dimethylformamide at 140-150°C for 11-13 hours, and then cooled, washed and dried to obtain MIL-88B.

7. A MOF-derived double-defect La 0.8 FeO 3-δ , characterized in that, The MOF-derived dual-defect La 0.8 FeO 3-δ Prepared by the preparation method according to any one of claims 1 to 6, the La 0.8 FeO 3-δ Contains La vacancies and O vacancies.

8. The MOF-derived double-defect La according to claim 7 0.8 FeO 3-δ Application in degradation of organic pollutants.

9. The use according to claim 8, characterized in that The organic pollutants include organic dyes, drugs, antiseptics and disinfectants, and industrial chemicals.

10. The use according to claim 9, characterized in that The drugs include levofloxacin, tetracycline and ibuprofen; the organic dyes include rhodamine B; the antiseptic disinfectants include phenol; and the industrial chemicals include bisphenol A.

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