Preparation method and application of Fe2O3-Bi4TaO8Br photo-Fenton catalyst

Abstract

This invention discloses a method for preparing and applying a Fe2O3-Bi4TaO8Br photo-Fenton catalyst, belonging to the field of advanced oxidation treatment technology. The specific preparation method includes: preparing Bi4TaO8Br nanosheets via a molten salt method, and then loading Fe2O3 onto the Bi4TaO8Br nanosheets via a hydrothermal method to obtain the Fe2O3-Bi4TaO8Br photo-Fenton catalyst. The Fe2O3-Bi4TaO8Br photo-Fenton catalyst prepared by this invention exhibits highly efficient photo-Fenton degradation performance of tetracycline (TC) under visible light conditions. Furthermore, the preparation process is safe, simple, and efficient, showing potential for environmental remediation applications.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a Fe2O3-Bi4TaO8Br photo-Fenton catalyst, belonging to the field of advanced oxidation treatment technology. Background Technology

[0002] Photo-Fenton technology, as an advanced oxidation treatment technology, combines the advantages of photocatalysis and Fenton technology. It effectively degrades antibiotic pollutants by generating reactive oxygen species such as hydroxyl radicals through light energy excitation, and is environmentally friendly. However, traditional photo-Fenton technology is limited by problems such as low visible light utilization of photocatalysts and rapid recombination of photogenerated electron-hole pairs, resulting in high processing costs.

[0003] Currently, many layered bismuth-based compounds have been used as environmental remediation catalysts, such as Bi m XO n (Bi2O3, Bi2S3, BiVO4, Bi2WO6, Bi2MoO6, Bi4Ti3O 12 Bismuth tantalum oxybromide (Bi4TaO8Br), as a Sillen-Aurivilius perovskite phase bismuth-based halide oxide, has attracted widespread attention. Compared to the bulk BiOBr crystal structure, the layered Bi4TaO8Br can expose more reaction sites. [Bi2O2] is present in Bi4TaO8Br. 2+ and [Br] - The layered structure of Bi4TaO8Br possesses a strong built-in electric field perpendicular to each ion layer, which can accelerate the transfer of photoinduced charge carriers along the

[001] direction. Simultaneously, the halogen layer consumes photogenerated holes, thereby improving the separation efficiency of photoinduced charge carriers and promoting reaction kinetics. However, the slow charge migration severely limits the catalytic performance of Bi4TaO8Br, and its poor structural and interfacial charge carrier separation efficiency hinders its practical application.

[0004] Existing research indicates that coupling with variable-valence metal-based semiconductors (such as Fe, Co, Ni, Cu, Zn, and Ce) can not only enhance light absorption performance but also activate the Fenton reaction through reaction with H₂O₂, thereby achieving excellent degradation performance. Fe₂O₃ was deposited on the surface of Bi₄TaO₈Br nanosheets via a hydrothermal method. Fe₂O₃, as a transition metal oxide, possesses advantages such as a narrow band gap of 2.20 eV, strong photooxidation properties, low cost, high conductivity, and environmental friendliness, making it a good co-catalyst. Furthermore, Fe₂O₃ has a more negative conduction band and valence level than Bi₄TaO₈Br. A novel Fe₂O₃-Bi₄TaO₈Br photocatalyst was prepared by modifying the surface of Bi₄TaO₈Br nanosheets with Fe₂O₃. Summary of the Invention

[0005] To address the problems existing in current photo-Fenton catalysts, one objective of this invention is to provide a method for preparing a Fe2O3-Bi4TaO8Br photo-Fenton catalyst, specifically including the following steps:

[0006] (1) Synthesis of BiOBr precursor: Bi(NO3)3·5H2O was weighed and dissolved in ethylene glycol to obtain solution I; KBr was weighed and dissolved in deionized water to obtain solution II. Solution II was added dropwise to solution I under stirring. After standing, the supernatant was discarded, the precipitate was washed and dried to obtain BiOBr.

[0007] (2) Bi4TaO8Br nanosheets were prepared by molten salt method: Ta2O5, Bi2O3 and BiOBr prepared in step (1) were weighed together, ground and placed in a crucible for calcination. After calcination, the product was naturally cooled and then washed with a centrifuge and dried to obtain Bi4TaO8Br nanosheets.

[0008] (3) Disperse the Bi4TaO8Br nanosheets prepared in step (2) into anhydrous ethanol. First, stir until the Bi4TaO8Br nanosheets and anhydrous ethanol are fully mixed. Then, add Fe(NO3)3·9H2O while stirring until Fe(NO3)3·9H2O is completely dissolved to obtain a suspension. Perform hydrothermal treatment on the suspension and cool it naturally to room temperature. After separation, washing, drying and collection, the Fe2O3-Bi4TaO8Br photo-Fenton catalyst is obtained.

[0009] Preferably, in step (1), the molar concentration of Bi(NO3)3·5H2O in solution I is 400-420 mmol / L, the molar concentration of KBr in solution II is 400-420 mmol / L, the volume ratio of solution I to solution II is 1:1, and the molar ratio of Bi(NO3)3·5H2O to KBr is 1:1.

[0010] Preferably, the stirring in step (1) is magnetic stirring, the stirring speed is 250-350 r / min, and the stirring temperature is 20-100℃.

[0011] Preferably, the molar ratio of Ta2O5, Bi2O3 and BiOBr in step (2) is (0.2-0.3):(0.7-0.8):(0.4-0.6).

[0012] Preferably, the calcination conditions in step (2) are: 10℃ min -1 The temperature was increased to 700℃ at a certain rate and held for 14 hours.

[0013] Preferably, in step (3), the mass molar ratio of Bi4TaO8Br nanosheets to Fe(NO3)3·9H2O is (0.15~0.25):(1~2), with units of g:mmol.

[0014] Preferably, the conditions for hydrothermal treatment in step (3) are: heat preservation temperature of 80-120℃ and heat preservation time of 5-8h.

[0015] Preferably, the washing step in step (3) is: thoroughly washing three times with distilled water and anhydrous ethanol respectively.

[0016] Beneficial effects of the present invention

[0017] (1) This invention synthesizes a novel Fe2O3-Bi4TaO8Br heterojunction catalyst via a hydrothermal method, broadening the application of bismuth oxybromide-based photo-Fenton catalyst. The prepared Fe2O3-Bi4TaO8Br photo-Fenton catalyst combines the high-efficiency oxidation characteristics of photo-Fenton technology with the excellent photoelectric properties of Bi4TaO8Br nanosheets, forming a synergistic composite material.

[0018] (2) This invention utilizes a molten salt synthesis method to construct Bi4TaO8Br nanosheets, which employ their internal electric field to provide a strong driving force for the photogenerated charge vector migration between Bi4TaO8Br and Fe2O3. Simultaneously, due to the formation of Fe-O bonds at the heterojunction interface, charge flow is accelerated, the charge transfer energy barrier is lowered, and effective charge separation is achieved, exhibiting excellent photo-Fenton degradation performance, with a degradation rate reaching 72.57% in 30 minutes.

[0019] (3) This invention enables Fe2O3 to grow on its surface through a simple operation process, which effectively overcomes the shortcomings of Bi4TaO8Br in terms of photogenerated carrier migration and light absorption. It has the advantages of simple method, low cost and good repeatability, which is conducive to industrial application in the field of environmental remediation. Attached Figure Description

[0020] Figure 1The XRD diffraction patterns of the photo-Fenton catalysts prepared in Examples 1, 2 and Comparative Examples 1, 2 and 3 are shown.

[0021] Figure 2 SEM images of the photo-Fenton catalysts prepared in Examples 1, 2 and Comparative Examples 1, 2 and 3.

[0022] Figure 3 The graph shows a comparison of the degradation performance of TC by the photo-Fenton catalysts prepared in Examples 1 and 2 and Comparative Examples 1, 2 and 3.

[0023] Figure 4 The UV-vis DRS diagrams are of the photo-Fenton catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0024] Figure 5 This is a stability test diagram of the photo-Fenton catalyst prepared in Example 1.

[0025] Figure 6 EIS performance tests were conducted on the photo-Fenton catalysts of Example 1 and Comparative Example 2.

[0026] Figure 7 The photo-Fenton catalysts of Example 1 and Comparative Example 2 exhibit photocurrent response. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0028] Unless otherwise specified, all reagents used in this invention are commercially available analytical grade reagents.

[0029] Example 1

[0030] The preparation method of a Fe2O3-Bi4TaO8Br photo-Fenton catalyst is as follows:

[0031] (1) Synthesis of BiOBr precursor: 10 mmol of Bi(NO3)3·5H2O and 10 mmol of KBr were weighed and dissolved in 25 mL of ethylene glycol and 25 mL of deionized water, respectively, to obtain solution I and solution II. Under magnetic stirring, solution II (KBr solution) was slowly added dropwise to solution II (Bi(NO3)3·5H2O ethylene glycol solution). After standing, the supernatant was discarded, washed, and dried to obtain BiOBr.

[0032] (2) Preparation of Bi4TaO8Br nanosheets by molten salt method: 0.1105 g of Ta2O5 and 0.3495 g of Bi2O3 were weighed and placed in a mortar, and then 0.5 mmol of BiOBr was weighed and placed in the mortar. After grinding together, the mixture was placed in a crucible and heated in a muffle furnace at 10 °C for min. -1The temperature was increased to 700℃ at a heating rate and held for 14 hours. After natural cooling, the calcined product was washed with a centrifuge and dried at 60℃ to obtain Bi4TaO8Br nanosheets.

[0033] (3) 0.2g of Bi4TaO8Br nanosheets were dispersed in anhydrous ethanol and magnetically stirred for 10 minutes under certain conditions. Then, 1mmol of Fe(NO3)3·9H2O was added under stirring until dissolved. The suspension was then transferred to a 50mL polyethylene-lined anti-oxidation steel autoclave for hydrothermal treatment. After naturally cooling to room temperature, the obtained product was separated, dried and collected to obtain the Fe2O3-Bi4TaO8Br photo-Fenton catalyst, which was named FEOBTB-2.

[0034] Example 2

[0035] The preparation method of a Fe2O3-Bi4TaO8Br photo-Fenton catalyst is as follows:

[0036] (1) Synthesis of BiOBr precursor. 10.5 mmol of Bi(NO3)3·5H2O and 10.5 mmol of KBr were weighed and dissolved in 25 mL of ethylene glycol and 25 mL of deionized water, respectively, to obtain solution I and solution II. Under magnetic stirring, solution II (KBr solution) was slowly added dropwise to solution I (Bi(NO3)3·5H2O ethylene glycol solution). After standing, the supernatant was discarded, washed, and dried to obtain BiOBr.

[0037] (2) Preparation of Bi4TaO8Br nanosheets by molten salt method: 0.1105 g of Ta2O5 and 0.3495 g of Bi2O3 were weighed and placed in a mortar, and then 0.6 mmol of BiOBr was weighed and placed in the mortar. After grinding together, the mixture was placed in a crucible and heated in a muffle furnace at 10 °C for 1 min. -1 The temperature was increased to 700℃ at a heating rate and held for 14 hours. After natural cooling, the calcined product was washed with a centrifuge and dried at 60℃ to obtain Bi4TaO8Br nanosheets.

[0038] (3) 0.15 g of Bi4TaO8Br nanosheets were dispersed in anhydrous ethanol and magnetically stirred for 10 minutes under certain conditions. Then, 2 mmol of Fe(NO3)3·9H2O was added while stirring until dissolved. The suspension was then transferred to a 50 mL polyethylene-lined anti-oxidation steel autoclave for hydrothermal treatment. After natural cooling to room temperature, the resulting product was separated, dried, and collected to obtain the Fe2O3-Bi4TaO8Br photo-Fenton catalyst, which was named FEOBTB-3.

[0039] Comparative Example 1

[0040] A method for preparing an Fe2O3 catalyst is described below:

[0041] (1) After stirring anhydrous ethanol at 300 r / min at 100 °C for 10 min, 1 mmol of Fe(NO3)3·9H2O was added under stirring until dissolved. Then, the suspension was transferred to a 50 mL polyethylene-lined antioxidant steel autoclave for hydrothermal treatment at 100 °C for 6 h. After naturally cooling to room temperature, the product was washed three times with distilled water and anhydrous ethanol, and dried at 60 °C overnight to obtain the Fe2O3 catalyst.

[0042] Comparative Example 2

[0043] The method for preparing Bi4TaO8Br nanosheets in this comparative example includes the following steps:

[0044] (1) Synthesis of BiOBr precursor: 10 mmol of Bi(NO3)3·5H2O and 10 mmol of KBr were weighed and dissolved in 25 mL of ethylene glycol and 25 mL of deionized water, respectively, to obtain solution I and solution II. Under magnetic stirring, solution II (KBr solution) was slowly added dropwise to solution II (Bi(NO3)3·5H2O ethylene glycol solution). After standing, the supernatant was discarded, washed, and dried to obtain BiOBr.

[0045] (2) Preparation of Bi4TaO8Br nanosheets by molten salt method: 0.1105 g of Ta2O5 and 0.3495 g of Bi2O3 were weighed and placed in a mortar, and then 0.5 mmol of BiOBr was weighed and placed in the mortar. After grinding together, the mixture was placed in a crucible and heated in a muffle furnace at 10 °C for min. -1 The temperature was increased to 700℃ at a heating rate and held for 14 hours. After natural cooling, the calcined product was washed with a centrifuge and dried at 60℃ to obtain Bi4TaO8Br nanosheets, which were named BTB.

[0046] Comparative Example 3

[0047] The preparation method of a Fe2O3-Bi4TaO8Br photo-Fenton catalyst is as follows:

[0048] (1) Synthesis of BiOBr precursor. 9.5 mmol of Bi(NO3)3·5H2O and 9.5 mmol of KBr were weighed and dissolved in 25 mL of ethylene glycol and 25 mL of deionized water, respectively, to obtain solution I and solution II. Under magnetic stirring, solution II (KBr solution) was slowly added dropwise to solution II (Bi(NO3)3·5H2O ethylene glycol solution). After standing, the supernatant was discarded, washed, and dried to obtain BiOBr.

[0049] (2) Preparation of Bi4TaO8Br nanosheets by molten salt method: 0.1105 g of Ta2O5 and 0.3495 g of Bi2O3 were weighed and placed in a mortar, and then 0.4 mmol of BiOBr was weighed and placed in the mortar. After grinding together, the mixture was placed in a crucible and heated in a muffle furnace at 10 °C for 1 min. -1 The temperature was increased to 700℃ at a heating rate and held for 14 hours. After natural cooling, the calcined product was washed with a centrifuge and dried at 60℃ to obtain Bi4TaO8Br nanosheets.

[0050] (3) 0.25 g of Bi4TaO8Br nanosheets were dispersed in anhydrous ethanol and magnetically stirred for 10 minutes under certain conditions. Then, 0.1 mmol of Fe(NO3)3·9H2O was added under stirring until dissolved. The suspension was then transferred to a 50 mL polyethylene-lined anti-oxidation steel autoclave for hydrothermal treatment. After naturally cooling to room temperature, the obtained product was separated, dried and collected to obtain the Fe2O3-Bi4TaO8Br photo-Fenton catalyst, which was named FEOBTB-1.

[0051] Photo-Fenton degradation experiment

[0052] The obtained catalyst was used for photo-Fenton degradation of tetracycline (TC), and the specific steps are as follows:

[0053] (1) Take 20 mg of catalyst and disperse it in 50 mL of tetracycline aqueous solution (the concentration of tetracycline is 10 mg / L). Use an ultrasonic cleaner to sonicate for about 5 min to mix it evenly. Finally, stir for 30 min under the dark to allow the catalyst and the target pollutant to reach an adsorption-desorption equilibrium state.

[0054] (2) The simulated solar light source uses a 10W white LED lamp with an energy intensity of 0.45mL, 30% w / w) H2O2 solution, and is placed under the light source for irradiation to initiate the photo-Fenton reaction.

[0055] (3) Take 5 mL of solution every 10 min and use a UV-Vis spectrophotometer (UV-2600) to measure the absorbance of tetracycline. The absorbance is set to λ = 357 nm. The concentration of antitetracycline is further calculated based on the standard curve of absorbance and concentration.

[0056] Results Analysis

[0057] Figure 1 The X-ray diffraction patterns of various photo-Fenton catalysts prepared in Examples 1, 2, 2, and 3 of this invention are shown. It can be seen from the figures that the characteristic peaks of Bi4TaO8Br nanosheets are consistent with the standard card. Furthermore, the prepared FEOBTB composite material also corresponds well with the characteristic peaks of Bi4TaO8Br nanosheets, confirming the construction of the FEOBTB composite material.

[0058] Figure 2 These are SEM images of various photo-Fenton catalysts prepared in Examples 1, 2, 1, 2, and 3 of this invention. From the images, it can be seen that Comparative Example 1 (… Figure 2 a) The prepared samples are spherical, with some exhibiting irregular small particle shapes; in Comparative Example 3 (Fig. b), a small number of Fe2O3 nanoparticles are visible on the surface of the Bi4TaO8Br nanosheets, and the surface begins to become less smooth; in Example 2 (Fig. c), the sheet-like structure of the sample begins to become irregular, with some parts starting to stack, and the surface shows significantly fewer Fe2O3 nanoparticles; in Comparative Example 2 (Fig. d), the sample has a typical two-dimensional nanosheet morphology, and no obvious Fe2O3 nanoparticles were found. The samples prepared in Example 1 (Figs. e, f) have a typical two-dimensional nanosheet morphology, and Fe2O3 nanoparticles can be clearly seen uniformly loaded on the surface of the thin sheets.

[0059] Figure 3 This is a comparison chart of the degradation performance of various photo-Fenton catalysts prepared in Examples 1, 2, 1, 2, and 3 of this invention on TC. It can be seen that the removal rate of TC by Bi4TaO8Br nanosheets (BTB) within 30 min of photo-Fenton is only 20.04%, and the removal rate of TC by Fe2O3 is only 66.32%. The introduction of Fe2O3 can significantly improve the photo-Fenton activity of Bi4TaO8Br nanosheets, but the amount of Fe2O3 introduced will affect the catalytic effect. Among them, the photo-Fenton degradation efficiency of the FEOBTB-2 sample is the highest, reaching 72.57%.

[0060] Figure 4 The images show the UV-vis DRS of the photo-Fenton catalysts prepared in Examples 1, 1, and 2 of this invention. It can be seen that the absorption edges of Bi4TaO8Br nanosheets (BTB) and Fe2O3 are located at 541.97 nm and 779.61 nm, respectively, while the absorption edge of FEOBTB-2 shows a significant red shift compared to Bi4TaO8Br, with the absorption edge located at 674.28 nm. This indicates that the light-harvesting ability of the FEOBTB-2 photo-Fenton catalyst is enhanced.

[0061] Figure 5 As shown, multiple cyclic experiments were conducted under the same conditions, demonstrating that the FEOBTB-2 photo-Fenton catalyst exhibits good stability. After four cycles of photo-Fenton degradation of TC, the FEOBTB-2 photo-Fenton catalyst still maintained considerable performance, and its good stability gives it potential for large-scale application.

[0062] Figure 6 As shown, in the EIS results ( Figure 6 The semicircle represented by the FEBTB sample is the smallest, while that represented by the BTB sample is the largest. The results indicate that the FEBTB heterojunction structure can reduce interfacial resistance, which is beneficial for the transfer and separation of photogenerated carriers. Figure 7 The photocurrent response was used. All tested samples exhibited photoresponse characteristics under illumination, with photocurrent densities of FEOBTB and BTB in that order. The highest photocurrent density of the FEOBTB sample indicates its optimal photocarrier separation and migration efficiency.

Claims

1. A method for preparing a Fe2O3-Bi4TaO8Br photo-Fenton catalyst, characterized in that: The preparation steps include the following: (1) Synthesis of BiOBr precursor: Weigh Bi(NO3)3•5H2O and dissolve it in ethylene glycol to obtain solution I; weigh KBr and dissolve it in deionized water to obtain solution II. Add solution II dropwise to solution I while stirring. After standing, discard the supernatant, wash the precipitate, and dry it to obtain BiOBr. (2) Bi4TaO8Br nanosheets were prepared by molten salt method: Ta2O5, Bi2O3 and BiOBr prepared in step (1) were weighed together, ground together and placed in a crucible for calcination. After calcination, the product was naturally cooled and then washed with a centrifuge and dried to obtain Bi4TaO8Br nanosheets. (3) Disperse the Bi4TaO8Br nanosheets prepared in step (2) into anhydrous ethanol. First, stir until the Bi4TaO8Br nanosheets and anhydrous ethanol are fully mixed. Then, add Fe(NO3)3•9H2O while stirring until Fe(NO3)3•9H2O is completely dissolved to obtain a suspension. Perform hydrothermal treatment on the suspension and cool it naturally to room temperature. After separation, washing, drying and collection of the obtained product, Fe2O3-Bi4TaO8Br photo-Fenton catalyst is obtained. The calcination conditions in step (2) are: 10℃ min -1 The temperature was increased to 700℃ at a heating rate and held for 14 hours; The conditions for hydrothermal treatment in step (3) are: heat preservation temperature of 80~120℃ and heat preservation time of 5~8h.

2. The preparation method of the Fe2O3-Bi4TaO8Br photo-Fenton catalyst according to claim 1, characterized in that: In step (1), the molar concentration of Bi(NO3)3•5H2O in solution I is 400~420 mmol / L, the molar concentration of KBr in solution II is 400~420 mmol / L, the volume ratio of solution I to solution II is 1:1, and the molar ratio of Bi(NO3)3•5H2O to KBr is 1:

1.

3. The method for preparing the Fe2O3-Bi4TaO8Br photo-Fenton catalyst according to claim 1, characterized in that: The stirring in step (1) is magnetic stirring, with a stirring speed of 250~350 r / min and a stirring temperature of 20~100℃.

4. The preparation method of the Fe2O3-Bi4TaO8Br photo-Fenton catalyst according to claim 1, characterized in that: In step (2), the molar ratio of Ta2O5, Bi2O3 and BiOBr is (0.2~0.3):(0.7~0.8):(0.4~0.6).

5. The preparation method of the Fe2O3-Bi4TaO8Br photo-Fenton catalyst according to claim 1, characterized in that: In step (3), the mass molar ratio of Bi4TaO8Br nanosheets to Fe(NO3)3•9H2O is (0.15~0.25):(1~2), with units of g:mmol.

6. The method for preparing the Fe2O3-Bi4TaO8Br photo-Fenton catalyst according to claim 1, characterized in that: The washing steps described in step (3) are as follows: wash thoroughly three times with distilled water and anhydrous ethanol respectively.

7. The application of the Fe2O3-Bi4TaO8Br photo-Fenton catalyst prepared by any one of claims 1 to 6 in the degradation of tetracycline in water.

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