A photocatalytic material, a preparation method therefor and an application thereof

Abstract

The application provides a kind of photocatalytic material and its preparation method and application, the preparation method of photocatalytic material, comprising the following steps: pretreated foam nickel is soaked, foam nickel after soaking is added to the mixed solution containing Bi (NO3) 3.5H2O and KI is reacted, the product after reaction is microwave treated to obtain photocatalytic material, the process of soaking includes: foam nickel is soaked in the solution containing Bi (NO3) 3.5H2O again in the solution containing K I after soaking.The photocatalytic material of the application can efficiently degrade sulfamethazine under natural light, and the recycling efficiency is relatively high, the sulfamethazine removal rate is 100% after 3 times of continuous use, 89% and 78.7% respectively in the 4th and 5th times.

Description

Technical Field

[0001] This invention relates to the technical field of catalyst preparation, specifically to a photocatalytic material, its preparation method, and its application. Background Technology

[0002] Semiconductor photocatalysts can degrade organic matter into water and carbon dioxide under ultraviolet or visible light irradiation, and have great potential in wastewater treatment, thus attracting extensive research.

[0003] Bismuth-based materials have attracted widespread attention and in-depth research due to their excellent photocatalytic performance and morphological diversity in the visible light (λ>420nm) region. Furthermore, composite materials formed from bismuth and other metals also exhibit good visible light photocatalytic performance. For example, bismuth oxyhalides (BiOX (X=Cl,Br,I)) have a tetragonal crystal structure, with BiO I attracting particular attention due to its small band gap (1.77–1.92 eV) and excellent absorption in the visible light region. However, the reusability efficiency of photocatalysts still has certain limitations; therefore, further development of existing technologies is needed. Summary of the Invention

[0004] To address the shortcomings of existing technologies and solve the aforementioned problems, a photocatalytic material, its preparation method, and its applications are proposed, and the following technical solution is provided:

[0005] A method for preparing a photocatalytic material includes the following steps: soaking pretreated nickel foam, adding the soaked nickel foam to a mixed solution containing Bi(NO3)3·5H2O and KI for reaction, and microwaving the product after reaction to obtain the photocatalytic material. The soaking process includes: soaking the nickel foam in a solution containing Bi(NO3)3·5H2O and then soaking it in a solution containing KI.

[0006] Furthermore, the soaking process is repeated 3-6 times.

[0007] Furthermore, after each soaking in a solution containing Bi(NO3)3·5H2O, the pretreated nickel foam is first soaked in deionized water for 15-25 seconds and then soaked in a solution containing KI. The pretreated nickel foam is then soaked in a solution containing KI and then soaked in deionized water for 15-25 seconds each time.

[0008] Furthermore, the pretreated nickel foam is immersed in a solution containing Bi(NO3)3·5H2O for 3-6 minutes each time, and the pretreated nickel foam is immersed in a solution containing KI for 3-6 minutes each time.

[0009] Furthermore, the concentration of Bi(NO3)3·5H2O in the solution containing Bi(NO3)3·5H2O is 40-80 mmol / L, and the concentration of KI in the solution containing KI is 40-80 mmol / L.

[0010] Furthermore, the solvent for the solution containing Bi(NO3)3·5H2O is dimethylformamide, and the solvent for the solution containing KI is water.

[0011] Furthermore, the microwave treatment time is 30-60 minutes, the microwave treatment temperature is 50-80°C, and the microwave treatment power is 200W-400W.

[0012] Furthermore, the pretreatment process of the nickel foam includes: ultrasonicating and cleaning the nickel foam, followed by calcination, with a calcination time of 1.5-2.5 h, a calcination temperature of 350-450 °C, and a heating rate of 8-15 °C / min.

[0013] In addition, the present invention also provides a photocatalytic material, which is prepared by the above-described method for preparing photocatalytic materials.

[0014] The present invention further provides the application of the above-mentioned photocatalytic material in the removal of sulfamethazine.

[0015] Beneficial effects:

[0016] 1. The photocatalytic material of the present invention can efficiently degrade sulfamethazine under natural light and has a high reusability. After three consecutive cycles, the removal rate of sulfamethazine is 100%, and the removal rates for the fourth and fifth cycles are 89% and 78.7%, respectively.

[0017] 2. Compared with existing photocatalytic materials, the stability and reusability of this invention are improved by using microwave assistance and pretreated foamed nickel. Attached Figure Description

[0018] Figure 1 This is a cyclic degradation diagram of the photocatalytic material prepared using pretreated nickel foam in Example 2 of the present invention;

[0019] Figure 2 This is a cyclic degradation diagram of the photocatalytic material prepared without nickel foam in Example 2 of the present invention;

[0020] Figure 3 This is a graph showing the change in Bi ion concentration of the photocatalytic material prepared using pretreated nickel foam in Example 2 of the present invention under different cycles.

[0021] Figure 4This is a graph showing the change in Bi ion concentration of the photocatalytic material prepared without nickel foam in Example 2 of the present invention under different cycles;

[0022] Figure 5 These are XRD patterns of pretreated nickel foam and untreated nickel foam from Example 2.

[0023] Figure 6 The images are FTIR images of Bi5O7I / NF photocatalyst material, powdered Bi5O7I, pretreated nickel foam, and untreated nickel foam in Example 2 of the invention.

[0024] Figure 7 This is a graph showing the performance of Bi5O7I / NF photocatalyst material in removing sulfamethazine under different light conditions in Example 4 of the invention;

[0025] Figure 8 This is a trend graph showing the effect of different Bi5O7I / NF photocatalyst dosages on the removal of sulfamethazine in Example 4 of the invention;

[0026] The above figures include the following reference numerals:

[0027] 1. XRD pattern of pretreated nickel foam; 2. XRD pattern of untreated nickel foam; 11. Infrared curve of Bi5O7I / NF photocatalyst; 12. Infrared curve of pretreated nickel foam; 13. Infrared curve of powdered Bi5O7I; 14. Infrared curve of untreated nickel foam; 21. Performance curve of Bi5O7I / NF photocatalyst for removing sulfamethazine under sunlight; 22. Performance curve of Bi5O7I / NF photocatalyst for removing sulfamethazine under simulated natural light; 23. Only the performance curves for removing sulfamethazine under simulated natural light are shown; 24. Performance curves for removing sulfamethazine from Bi5O7I / NF photocatalyst under darkness are shown; 31. Bi5O7I / NF dosage is 60 pieces / L; 32. Bi5O7I / NF dosage is 120 pieces / L; 33. Bi5O7I / NF dosage is 180 pieces / L; 34. Bi5O7I / NF dosage is 240 pieces / L; 35. Bi5O7I / NF dosage is 350 pieces / L; 36. Bi5O7I / NF dosage is 500 pieces / L. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application.

[0029] According to an embodiment of the present invention, a method for preparing a photocatalytic material is provided, comprising the following steps: soaking pretreated nickel foam, adding the soaked nickel foam to a mixed solution containing Bi(NO3)3·5H2O and KI for reaction, and subjecting the reaction product to microwave treatment to obtain the photocatalytic material. The soaking process includes: soaking the nickel foam in a solution containing Bi(NO3)3·5H2O and then soaking it in a solution containing KI.

[0030] Example 1: Investigating the effect of the immersion process on the catalytic performance of photocatalytic materials (I): The number of repetitions of the immersion process were controlled to be 3, 5 and 6 times respectively.

[0031] The photocatalytic material was prepared according to the following steps:

[0032] (1) Nickel foam pretreatment

[0033] Nickel foam was cut into 1cm × 1cm sheets, immersed in acetone and sonicated for 20 minutes, then washed with deionized water; then immersed in hydrochloric acid (10 mmol) for 20 minutes, washed again with deionized water, and then dried in a vacuum oven at 70℃. Finally, it was placed in a box furnace and heated to 400℃ at a rate of 10℃ / min for 2 hours to obtain nickel foam containing nickel oxide, which was then ready for use.

[0034] (2) Synthesis of photocatalytic materials

[0035] Step 1: Under magnetic stirring, dissolve Bi(NO3)3·5H2O (3 mmol) in 50 mL of dimethylformamide (DMF) to form solution A. Prepare 50 mL of KI aqueous solution (3 mmol) as solution B. Immerse the pretreated nickel foam in solution A for 4 min, then in deionized water for 20 s, then in solution B for 4 min, and then in deionized water for 20 s. Repeat the four-step immersion procedure as required above, and then dry under vacuum at 70 °C for 2 h. Step 2: Pour 100 mL of ethylene glycol into a 250 mL beaker, add Bi(NO3)3·5H2O (6 mmol), and sonicate until dissolved; transfer to magnetic stirring, add KI (6 mmol), and the reaction system forms an orange-red homogeneous system to obtain solution C. Then add the nickel foam obtained in step 1 to solution C and continue stirring for 40 min; then add 1 mol / L NaOH solution dropwise to adjust the pH to 5, and a precipitate will form. Then, the mixture was transferred to a microwave oven at room temperature and pressure and heated to 60°C for 40 minutes. In the third step, after the reaction was complete and the reaction solution cooled to room temperature, the attached nickel foam was removed. It was then placed in a 70°C oven and dried for 18 hours. The material was then rinsed with ethanol and dried again to obtain the Bi5O7I / NF photocatalyst material.

[0036] Meanwhile, a comparative experiment was conducted. The pretreated nickel foam was added directly to a mixed solution containing Bi(NO3)3·5H2O and KI without soaking, and the other steps were the same as the preparation method of the photocatalytic material in Example 1.

[0037] The degradation rate of sulfamethazine was tested using the photocatalytic material prepared in Example 1(a) and the photocatalytic material obtained in the comparative experiment. 100 mL of a 10 mg / L sulfamethazine solution was placed in a photoreactor, and 35 pieces of the prepared photocatalytic material were added. The condenser was turned on, and the mixture was magnetically stirred for 30 min in the dark until adsorption equilibrium was reached, at which point a sample was taken. Then, a xenon lamp was turned on to start the photocatalytic degradation reaction, and samples were taken at specific times. The samples were filtered through a 0.22 μm aqueous filter membrane and stored in an ice bath at 0 °C for later analysis. The concentration of sulfamethazine was detected by high-performance liquid chromatography (HPLC). The mobile phase was water / acetonitrile (40 / 60, V / V), the flow rate was 0.2 mL / min, and the detection wavelength was 270 nm. The degradation rate of sulfamethazine was calculated based on the measured peak area and the standard curve. The test results are shown in Table 1.

[0038] Table 1. Degradation rate of sulfamethazine by photocatalysts prepared with different immersion process repetitions.

[0039]

[0040]

[0041] As shown in Table 1 above, the degradation rate of the photocatalytic material without soaking is 95%, while the degradation rate is 100% after four soaking cycles. However, the degradation rate of the photocatalytic material without soaking decreases from 95% to 54.93% after one cycle, and drops further to 42.58% after three cycles. The degradation rate of the photocatalytic material after five soaking cycles remains 100%. Furthermore, the degradation rates of the photocatalytic materials after three and six soaking cycles are both above 90%. This demonstrates that the soaking process is crucial for the stability, safety, and operability of the photocatalytic material and cannot be omitted. Too few soaking cycles reduce the adhesion of iodine and bismuth ions on the surface, hindering the growth of crystal nuclei in the next step. Too many soaking cycles may lead to dense aggregation of Bi5O7I, reducing the effective active sites. During the soaking process, the pretreated nickel foam was soaked in a solution containing Bi(NO3)3·5H2O, then in deionized water for 15-25 seconds, and finally in a solution containing KI. The pH of the solution significantly affects the valence state of Bi; both excessively acidic and excessively alkaline solutions are detrimental to photocatalytic performance. Soaking in water helps adjust the pH to an appropriate range.

[0042] Furthermore, without soaking, if the pH value is not adjusted to 5 by adding 1 mol / L NaOH solution, the degradation rate of the prepared photocatalytic material is only 76.71%.

[0043] (II): The order of soaking nickel foam in solutions containing Bi(NO3)3·5H2O and KI during the soaking process is controlled as follows: First method: soak nickel foam in a solution containing Bi(NO3)3·5H2O for 4 min, soak in deionized water for 20 s, then soak in a solution containing KI for 4 min, and then soak in deionized water for 20 s; Second method: soak nickel foam in a solution containing KI for 4 min, soak in deionized water for 20 s, then soak in a solution containing Bi(NO3)3·5H2O for 4 min, and then soak in deionized water for 20 s; Third method: soak nickel foam only in a solution containing Bi(NO3)3·5H2O; Fourth method: soak nickel foam only in a solution containing KI.

[0044] The photocatalytic material was prepared according to the following steps:

[0045] (1) Nickel foam pretreatment

[0046] Nickel foam was cut into 1cm × 1cm sheets, immersed in acetone and sonicated for 20 minutes, then washed with deionized water; then immersed in hydrochloric acid (10 mmol) for 20 minutes, washed again with deionized water, and then dried in a vacuum oven at 70℃. Finally, it was placed in a box furnace and heated to 400℃ at a rate of 10℃ / min for 2 hours to obtain nickel foam containing nickel oxide, which was then ready for use.

[0047] (2) Synthesis of photocatalytic materials

[0048] Step 1: Under magnetic stirring, dissolve Bi(NO3)3·5H2O (3 mmol) in 50 mL of dimethylformamide (DMF) to form solution A. Prepare 50 mL of KI aqueous solution (3 mmol) as solution B. Repeat the above soaking sequence 5 times, and then dry under vacuum at 70℃ for 2 h. Step 2: Pour 100 mL of ethylene glycol into a 250 mL beaker, add Bi(NO3)3·5H2O (6 mmol), and sonicate until dissolved; transfer to magnetic stirring, add KI (6 mmol), and the reaction system forms an orange-red homogeneous system to obtain solution C. Then add the nickel foam obtained in step 1 to solution C and continue stirring for 40 min; then add 1 mol / L NaOH solution dropwise to adjust the pH to 5, forming a precipitate. Then transfer to microwave heating at room temperature and pressure to 60℃ and react for 40 min. Step 3: After the reaction is complete, let the reaction solution cool to room temperature and remove the attached nickel foam precipitate. The material was dried in a 70℃ oven for 18 hours. Then, it was rinsed with ethanol and dried again to obtain the Bi5O7I / NF photocatalytic material.

[0049] The degradation rate of sulfamethazine by the photocatalytic material prepared in Example 1 (II) was tested. 100 mL of a 10 mg / L sulfamethazine solution was placed in a photoreactor, and 35 pieces of the prepared photocatalytic material were added. The condenser was turned on, and the mixture was magnetically stirred for 30 min in the dark until adsorption equilibrium was reached, at which point a sample was taken. Then, a xenon lamp was turned on to begin the photocatalytic degradation reaction, and samples were taken at specific times. The samples were filtered through a 0.22 μm aqueous filter membrane and stored in an ice bath at 0 °C for later analysis. The concentration of sulfamethazine was detected by high-performance liquid chromatography (HPLC). The mobile phase was water / acetonitrile (40 / 60, V / V), the flow rate was 0.2 mL / min, and the detection wavelength was 270 nm. The degradation rate of sulfamethazine was calculated based on the measured peak area and the standard curve. The test results are shown in Table 2.

[0050] Table 2. Degradation rate of sulfamethazine by photocatalysts prepared with different soaking sequences.

[0051]

[0052] The positively charged end of the N,N-dimethylformamide molecule is surrounded by a methyl group, creating a steric hindrance that prevents negative ions from approaching and only associates with positive ions. Therefore, soaking in a Bi(NO3)3·5H2O solution beforehand facilitates the chemical bonding of Bi and I ions with the nickel foam.

[0053] (iii) Adjusting the soaking liquid: a) soaking in a solution containing Bi(NO3)3·5H2O and then soaking in a solution containing KI; b) soaking in dimethylformamide.

[0054] The photocatalytic material was prepared under condition a:

[0055] (1) Nickel foam pretreatment

[0056] Nickel foam was cut into 1cm × 1cm sheets, immersed in acetone and sonicated for 20 minutes, then washed with deionized water; then immersed in hydrochloric acid (10 mmol) for 20 minutes, washed again with deionized water, and then dried in a vacuum oven at 70℃. Finally, it was placed in a box furnace and heated to 400℃ at a rate of 10℃ / min for 2 hours to obtain nickel foam containing nickel oxide, which was then ready for use.

[0057] (2) Synthesis of photocatalytic materials

[0058] Step 1: Under magnetic stirring, dissolve Bi(NO3)3·5H2O (3 mmol) in 50 mL of dimethylformamide (DMF) to form solution A. Prepare 50 mL of KI aqueous solution (3 mmol) as solution B. Immerse the pretreated nickel foam in solution A for 4 min, then in deionized water for 20 s, then in solution B for 4 min, and then in deionized water for 20 s. Repeat this four-step immersion procedure 5 times, and then dry under vacuum at 70 °C for 2 h. Step 2: Pour 100 mL of ethylene glycol into a 250 mL beaker, add Bi(NO3)3·5H2O (6 mmol), and sonicate until dissolved; transfer to magnetic stirring, add KI (6 mmol), and the reaction system forms an orange-red homogeneous system to obtain solution C. Then add the nickel foam obtained in step 1 to solution C and continue stirring for 40 min; then add 1 mol / L NaOH solution dropwise to adjust the pH to 5, and a precipitate will form. Then, the mixture was transferred to a microwave oven at room temperature and pressure and heated to 60°C for 40 minutes. In the third step, after the reaction was complete and the reaction solution cooled to room temperature, the attached nickel foam was removed. It was then placed in a 70°C oven and dried for 18 hours. The material was then rinsed with ethanol and dried again to obtain the Bi5O7I / NF photocatalyst material.

[0059] The photocatalytic material was prepared under condition b:

[0060] (1) Nickel foam pretreatment

[0061] Nickel foam was cut into 1cm × 1cm sheets, immersed in acetone and sonicated for 20 minutes, then washed with deionized water; then immersed in hydrochloric acid (10 mmol) for 20 minutes, washed again with deionized water, and then dried in a vacuum oven at 70℃. Finally, it was placed in a box furnace and heated to 400℃ at a rate of 10℃ / min for 2 hours to obtain nickel foam containing nickel oxide, which was then ready for use.

[0062] (2) Synthesis of photocatalytic materials

[0063] The first step involves immersing the pretreated nickel foam in solution A for 4 minutes, then in deionized water for 20 seconds, followed by immersion in dimethylformamide for 4 minutes, and then in deionized water for another 20 seconds. The foam is then dried under vacuum at 70°C for 2 hours. The second step involves adding 100 mL of ethylene glycol to a 250 mL beaker, adding Bi(NO3)3·5H2O (6 mmol), and sonicating until dissolved. The mixture is then transferred to a magnetically stirred container, and KI (6 mmol) is added. The reaction system forms an orange-red homogeneous system, resulting in solution C. The nickel foam obtained in the first step is then added to solution C, and stirring continues for 40 minutes. A 1 mol / L NaOH solution is then added dropwise to adjust the pH to 5, causing a precipitate to form. The precipitate is then heated to 60°C in a microwave oven at room temperature and pressure for 40 minutes. The third step involves allowing the reaction solution to cool to room temperature and removing the attached nickel foam precipitate. The precipitate is then dried in a 70°C oven for 18 hours. The material is then rinsed with ethanol and dried again to obtain the photocatalytic material.

[0064] The degradation rate of sulfamethazine by the photocatalytic material prepared in Example 1 (III) was tested. 100 mL of a 10 mg / L sulfamethazine solution was placed in a photoreactor, and 35 pieces of the prepared photocatalytic material were added. The condenser was turned on, and the mixture was magnetically stirred for 30 min in the dark until adsorption equilibrium was reached, at which point a sample was taken. Then, a xenon lamp was turned on to begin the photocatalytic degradation reaction, and samples were taken at specific times. The samples were filtered through a 0.22 μm aqueous filter membrane and stored in an ice bath at 0 °C for later analysis. The concentration of sulfamethazine was detected by high-performance liquid chromatography (HPLC). The mobile phase was water / acetonitrile (40 / 60, V / V), the flow rate was 0.2 mL / min, and the detection wavelength was 270 nm. The degradation rate of sulfamethazine was determined based on the measured peak area and the standard curve.

[0065] The degradation rate of the photocatalytic material prepared under condition a was 100%, while under condition b, the degradation rate was 90.02%.

[0066] Example 2 investigates the effect of pretreated nickel foam on the catalytic performance of photocatalytic materials. (one):

[0068] The photocatalytic material was prepared according to the following steps:

[0069] (1) Nickel foam pretreatment

[0070] Nickel foam was cut into 1cm × 1cm sheets, immersed in acetone and sonicated for 20 minutes, then washed with deionized water; then immersed in hydrochloric acid (10 mmol) for 20 minutes, washed again with deionized water, and then dried in a vacuum oven at 70℃. Finally, it was placed in a box furnace and heated to 400℃ at a rate of 10℃ / min for 2 hours to obtain nickel foam containing nickel oxide, which was then ready for use.

[0071] (2) Synthesis of photocatalytic materials

[0072] Step 1: Under magnetic stirring, dissolve Bi(NO3)3·5H2O (3 mmol) in 50 mL of dimethylformamide (DMF) to form solution A. Prepare 50 mL of KI aqueous solution (3 mmol) as solution B. Immerse the pretreated nickel foam in solution A for 4 min, then in deionized water for 20 s, then in solution B for 4 min, and then in deionized water for 20 s. Repeat the four-step immersion procedure five times as required above, and then dry under vacuum at 70 °C for 2 h. Step 2: Pour 100 mL of ethylene glycol into a 250 mL beaker, add Bi(NO3)3·5H2O (6 mmol), and sonicate until dissolved; transfer to magnetic stirring, add KI (6 mmol), and the reaction system forms an orange-red homogeneous system to obtain solution C. Then add the nickel foam obtained in step 1 to solution C and continue stirring for 40 min; then add 1 mol / L NaOH solution dropwise to adjust the pH to 5, and a precipitate will form. Then, the mixture was transferred to a microwave oven at room temperature and pressure and heated to 60°C for 40 minutes. In the third step, after the reaction was complete and the reaction solution cooled to room temperature, the attached nickel foam was removed. It was then placed in a 70°C oven and dried for 18 hours. The material was then rinsed with ethanol and dried again to obtain the Bi5O7I / NF photocatalyst material.

[0073] Meanwhile, a comparative experiment was conducted. Without adding the pretreated nickel foam, the reaction was carried out directly using a mixed solution containing Bi(NO3)3·5H2O and KI. The other steps were the same as the preparation method of the photocatalytic material in Example 2, and Bi5O7I powder was obtained.

[0074] The degradation rate of sulfamethazine was tested using the photocatalytic material prepared in Example 2(a) and the photocatalytic material obtained in the comparative experiment. 100 mL of a 10 mg / L sulfamethazine solution was placed in a photoreactor, and 35 pieces of the prepared photocatalytic material were added. The condenser was turned on, and the mixture was magnetically stirred for 30 min in the dark until adsorption equilibrium was reached, at which point a sample was taken. Then, a xenon lamp was turned on to start the photocatalytic degradation reaction, and samples were taken at specific times. The samples were filtered through a 0.22 μm aqueous filter membrane and stored in an ice bath at 0 °C for later analysis. The concentration of sulfamethazine was detected by high-performance liquid chromatography (HPLC). The mobile phase was water / acetonitrile (40 / 60, V / V), the flow rate was 0.2 mL / min, and the detection wavelength was 270 nm. The degradation rate of sulfamethazine was calculated based on the measured peak area and the standard curve, as detailed below. Figures 1-4 As shown, Figure 1 The degradation rate of sulfamethazine (SMR) by the photocatalytic material Bi5O7I / NF under different cycles was demonstrated. After three consecutive cycles, the sulfamethazine removal rate of Bi5O7I / NF was 100%, while the rates were 89% and 78.7% after the fourth and fifth cycles, respectively, demonstrating the stability of the system. Figure 2 The degradation rate of sulfamethazine (SMR) in Bi5O7I powder under different cycles is shown. The removal rate of sulfamethazine decreased significantly after each cycle. Obviously, the stability of Bi5O7I / NF is significantly better than that of Bi5O7I powder. Figure 3 The change in the concentration of Bi5O7I / NF ions dissolved in this system. Figure 4 The change in ion dissolution concentration of Bi5O7I powder in this system was compared. Figure 3 and Figure 4 The dissolution concentration of Bi ions in Bi5O7I / NF was significantly lower than that of Bi ions in Bi5O7I powder, indicating that the introduced pretreated nickel foam effectively reduced the metal ion dissolution concentration. Furthermore, the 3D structure of Bi5O7I / NF can be easily separated and recovered from the solution, and can be reused after simple rinsing. Compared to the Bi5O7I monomer material, the composite catalyst has a more stable structure and a lower metal ion dissolution concentration. Figure 3 As shown, the highest leaching concentration of Bi ions in the solution after using Bi5O7I / NF (14.242 μg / L) meets the allowable detection limit (GB 3838–2002, China) and is far lower than the ion leaching concentration of Bi5O7I. This indicates that the introduced pretreated nickel foam effectively reduces the leaching concentration of metal ions. The excellent separation performance and high stability for repeated use greatly simplify the recovery and reuse procedures of Bi5O7I / NF.

[0075] (II): The effect of pretreated and untreated nickel foam on the catalytic performance of photocatalytic materials. The photocatalytic materials were prepared according to the following steps:

[0076] (1) Nickel foam pretreatment

[0077] Nickel foam was cut into 1cm × 1cm sheets, immersed in acetone and sonicated for 20 minutes, then washed with deionized water; then immersed in hydrochloric acid (10 mmol) for 20 minutes, washed again with deionized water, and then dried in a vacuum oven at 70℃. Finally, it was placed in a box furnace and heated to 400℃ at a rate of 10℃ / min for 2 hours to obtain nickel foam containing nickel oxide, which was then ready for use.

[0078] (2) Synthesis of photocatalytic materials

[0079] Step 1: Under magnetic stirring, dissolve Bi(NO3)3·5H2O (3 mmol) in 50 mL of dimethylformamide (DMF) to form solution A. Prepare 50 mL of KI aqueous solution (3 mmol) as solution B. Immerse the pretreated nickel foam in solution A for 4 min, then in deionized water for 20 s, then in solution B for 4 min, and then in deionized water for 20 s. Repeat the four-step immersion procedure five times as required above, and then dry under vacuum at 70 °C for 2 h. Step 2: Pour 100 mL of ethylene glycol into a 250 mL beaker, add Bi(NO3)3·5H2O (6 mmol), and sonicate until dissolved; transfer to magnetic stirring, add KI (6 mmol), and the reaction system forms an orange-red homogeneous system to obtain solution C. Then add the nickel foam obtained in step 1 to solution C and continue stirring for 40 min; then add 1 mol / L NaOH solution dropwise to adjust the pH to 5, and a precipitate will form. Then, the mixture was transferred to a microwave oven at room temperature and pressure and heated to 60°C for 40 minutes. In the third step, after the reaction was complete and the reaction solution cooled to room temperature, the attached nickel foam was removed. It was then placed in a 70°C oven and dried for 18 hours. The material was then rinsed with ethanol and dried again to obtain the Bi5O7I / NF photocatalyst material.

[0080] Meanwhile, a comparative experiment was conducted in which the nickel foam was not pretreated, and the other steps were the same as the preparation method of the photocatalytic material in Example 2 (II).

[0081] First, XRD tests were performed on pretreated and untreated nickel foam. The test results are as follows: Figure 5 As shown, by Figure 5 It can be seen that the diffraction peaks at 37.2°, 43.297°, and 62.895° correspond to the (111), (200), and (220) crystal planes of NiO, respectively, indicating that the pretreated nickel foam contains NiO. In addition, infrared spectroscopy was performed on the Bi5O7I / NF photocatalyst material, the pretreated nickel foam, the untreated nickel foam, and Bi5O7I, as shown in the results. Figure 6As shown in the figure, compared with pure nickel foam, the pretreated nickel foam has a thickness of 400-700 cm⁻¹. -1 The presence of characteristic peaks for Ni-O tensile vibration indicates the formation of NiO on the surface of the nickel foam. Simultaneously, characteristic peaks for both NiO and Bi5O7I were observed in the Bi5O7I / nickel foam composite catalyst, indicating that the final composite catalyst consists of NiO and Bi5O7I.

[0082] Next, the degradation rate of sulfamethazine was tested using the photocatalytic material prepared in Example 2 (II) and the photocatalytic material obtained in the comparative experiment. 100 mL of a 10 mg / L sulfamethazine solution was placed in a photoreactor, and 35 pieces of the above-prepared photocatalytic material were added. The condenser was turned on, and the mixture was magnetically stirred for 30 min in the dark until adsorption equilibrium was reached, at which point a sample was taken. Then, a xenon lamp was turned on to start the photocatalytic degradation reaction, and samples were taken at specific times. The samples were filtered through a 0.22 μm aqueous filter membrane and stored in an ice bath at 0 °C for later analysis. The concentration of sulfamethazine was detected by high-performance liquid chromatography (HPLC). The mobile phase was water / acetonitrile (40 / 60, V / V), the flow rate was 0.2 mL / min, and the detection wavelength was 270 nm. The degradation rate of sulfamethazine was calculated based on the measured peak area and the standard curve. The specific results are shown in Table 3.

[0083] Table 3. Effect of nickel foam pretreatment on the degradation rate of sulfamethazine.

[0084]

[0085] The introduction of nickel oxide leads to the formation of lattice oxygen, oxygen vacancies, and adsorbed oxygen in the composite material. In particular, the presence of oxygen vacancies can modulate the band structure, serving as active sites while promoting carrier separation. After the formation of nickel oxide, the surface roughness of the nickel foam increases, which is conducive to the adhesion and growth of Bi5O7I, thus increasing stability. The catalyst can remain stable even after multiple cycles.

[0086] Example 3 investigates the effect of microwave treatment on the catalytic performance of photocatalytic materials.

[0087] The photocatalytic material was prepared according to the following steps:

[0088] (1) Nickel foam pretreatment

[0089] Nickel foam was cut into 1cm × 1cm sheets, immersed in acetone and sonicated for 20 minutes, then washed with deionized water; then immersed in hydrochloric acid (10 mmol) for 20 minutes, washed again with deionized water, and then dried in a vacuum oven at 70℃. Finally, it was placed in a box furnace and heated to 400℃ at a rate of 10℃ / min for 2 hours to obtain nickel foam containing nickel oxide, which was then ready for use.

[0090] (2) Synthesis of photocatalytic materials

[0091] Step 1: Under magnetic stirring, dissolve Bi(NO3)3·5H2O (3 mmol) in 50 mL of dimethylformamide (DMF) to form solution A. Prepare 50 mL of KI aqueous solution (3 mmol) as solution B. Immerse the pretreated nickel foam in solution A for 4 min, then in deionized water for 20 s, then in solution B for 4 min, and then in deionized water for 20 s. Repeat the four-step immersion procedure five times as required above, and then dry under vacuum at 70 °C for 2 h. Step 2: Pour 100 mL of ethylene glycol into a 250 mL beaker, add Bi(NO3)3·5H2O (6 mmol), and sonicate until dissolved; transfer to magnetic stirring, add KI (6 mmol), and the reaction system forms an orange-red homogeneous system to obtain solution C. Then add the nickel foam obtained in step 1 to solution C and continue stirring for 40 min; then add 1 mol / L NaOH solution dropwise to adjust the pH to 5, and a precipitate will form. Then, the mixture was transferred to a microwave oven at room temperature and pressure and heated to 60°C for 40 minutes. In the third step, after the reaction was complete and the reaction solution cooled to room temperature, the attached nickel foam was removed. It was then placed in a 70°C oven and dried for 18 hours. The material was then rinsed with ethanol and dried again to obtain the Bi5O7I / NF photocatalyst material.

[0092] Meanwhile, a comparative experiment was conducted without microwave treatment, and the other steps were the same as the preparation method of the photocatalytic material in Example 3.

[0093] The degradation rate of sulfamethazine was tested using the photocatalytic material prepared in Example 3 and the photocatalytic material obtained in the comparative experiment. 100 mL of a 10 mg / L sulfamethazine solution was placed in a photoreactor, and 35 pieces of the prepared photocatalytic material were added. The condenser was turned on, and the mixture was magnetically stirred for 30 min in the dark until adsorption equilibrium was reached, at which point a sample was taken. Then, a xenon lamp was turned on to start the photocatalytic degradation reaction, and samples were taken at specific times. The samples were filtered through a 0.22 μm aqueous filter membrane and stored in an ice bath at 0 °C for later analysis. The concentration of sulfamethazine was detected by high-performance liquid chromatography (HPLC). The mobile phase was water / acetonitrile (40 / 60, V / V), the flow rate was 0.2 mL / min, and the detection wavelength was 270 nm. The degradation rate of sulfamethazine was calculated based on the measured peak area and the standard curve. The specific results are shown in Table 4 below.

[0094] Table 4. Effect of microwave treatment on the degradation rate of sulfamethazine.

[0095]

[0096] The degradation effect of photocatalysts without microwave treatment is lower than that of photocatalysts with microwave treatment. Microwave treatment can accelerate crystal formation, shorten aging time, and increase surface active sites.

[0097] Example 4

[0098] The photocatalytic material was prepared according to the following steps:

[0099] (1) Nickel foam pretreatment

[0100] Nickel foam was cut into 1cm × 1cm sheets, immersed in acetone and sonicated for 20 minutes, then washed with deionized water; then immersed in hydrochloric acid (10 mmol) for 20 minutes, washed again with deionized water, and then dried in a vacuum oven at 70℃. Finally, it was placed in a box furnace and heated to 400℃ at a rate of 10℃ / min for 2 hours to obtain nickel foam containing nickel oxide, which was then ready for use.

[0101] (2) Synthesis of photocatalytic materials

[0102] Step 1: Under magnetic stirring, dissolve Bi(NO3)3·5H2O (3 mmol) in 50 mL of dimethylformamide (DMF) to form solution A. Prepare 50 mL of KI aqueous solution (3 mmol) as solution B. Immerse the pretreated nickel foam in solution A for 4 min, then in deionized water for 20 s, then in solution B for 4 min, and then in deionized water for 20 s. Repeat the four-step immersion procedure five times as required above, and then dry under vacuum at 70 °C for 2 h. Step 2: Pour 100 mL of ethylene glycol into a 250 mL beaker, add Bi(NO3)3·5H2O (6 mmol), and sonicate until dissolved; transfer to magnetic stirring, add KI (6 mmol), and the reaction system forms an orange-red homogeneous system to obtain solution C. Then add the nickel foam obtained in step 1 to solution C and continue stirring for 40 min; then add 1 mol / L NaOH solution dropwise to adjust the pH to 5, and a precipitate will form. Then, the mixture was transferred to a microwave oven at room temperature and pressure and heated to 60°C for 40 minutes. In the third step, after the reaction was complete and the reaction solution cooled to room temperature, the attached nickel foam was removed. It was then placed in a 70°C oven and dried for 18 hours. The material was then rinsed with ethanol and dried again to obtain the Bi5O7I / NF photocatalyst material.

[0103] The degradation rate of sulfamethazine by the Bi5O7I / NF photocatalyst material prepared in Example 4 was tested under different light conditions. The Bi5O7I / NF photocatalyst material was tested in darkness, under sunlight, under simulated natural light, and under conditions without the addition of Bi5O7I / NF photocatalyst material. Figure 7It can be seen that when there is no photocatalyst in the system and only light irradiation, the concentration of sulfamethazine only changes slightly, which can be attributed to adsorption. When Bi5O7I / nickel foam is present in the system but no light is involved, the concentration of sulfamethazine hardly changes. However, when both the catalyst and light are present in the system, the removal rates of sulfamethazine under simulated sunlight and sunlight irradiation reach 100% and 95.27%, respectively. This indicates that Bi5O7I / nickel foam is a highly active composite photocatalyst that can efficiently degrade sulfamethazine in the aquatic environment under natural light excitation.

[0104] The degradation rate of sulfamethazine was tested using the Bi5O7I / NF photocatalyst material prepared in Example 4. During the test, the amount of Bi5O7I / NF photocatalyst material added was adjusted. 1 L of a 10 mg / L sulfamethazine solution was placed in the photoreactor, and different numbers of the prepared photocatalyst material were added. The condenser was turned on, and the mixture was magnetically stirred for 30 min in the dark until adsorption equilibrium was reached, at which point a sample was taken. Then, a xenon lamp was turned on to start the photocatalytic degradation reaction, and samples were taken at specific times. The samples were filtered through a 0.22 μm aqueous filter and stored in an ice bath at 0 °C for later analysis. The concentration of sulfamethazine was detected by high-performance liquid chromatography (HPLC). The mobile phase was water / acetonitrile (40 / 60, V / V), the flow rate was 0.2 mL / min, and the detection wavelength was 270 nm. The degradation rate of sulfamethazine was calculated based on the measured peak area and the standard curve. Figure 8 The results showed that the removal rate of sulfamethazine increased with increasing Bi5O7I / NF dosage, corresponding to an increase in the number of active sites. The highest removal rate (100%) of sulfamethazine was achieved within 70 minutes when the Bi5O7I / NF dosage was 350 tablets / L. However, when the catalyst dosage in the system was further increased (to 500 tablets / L), the removal rate decreased. -1 The removal rate of sulfamethazine decreased instead of increasing. This may be because the stacked sheet catalysts hindered the transmission of light in the water and reduced the reflection of light between the catalysts, thereby reducing the utilization rate of light.

[0105] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a photocatalytic material, characterized in that, Includes the following steps: The pretreated nickel foam is soaked, and the soaked nickel foam is added to a mixed solution containing Bi(NO3)3·5H2O and KI for reaction. The product after reaction is microwave treated to obtain Bi5O7I / NF photocatalytic material. The soaking process includes: soaking the nickel foam in a solution containing Bi(NO3)3·5H2O and then soaking it in a solution containing KI. The soaking process is repeated 3-6 times; The pretreated nickel foam is soaked in a solution containing Bi(NO3)3·5H2O, then soaked in deionized water for 15-25 seconds, and then soaked in a solution containing KI. The pretreated nickel foam is soaked in a solution containing KI and then soaked in deionized water for 15-25 seconds each time. The pretreatment process of the nickel foam includes: ultrasonicating and cleaning the nickel foam, followed by calcination to obtain nickel foam containing nickel oxide. The calcination time is 1.5-2.5 h, the calcination temperature is 350-450 ℃, and the heating rate is 8-15 ℃ / min.

2. The method for preparing the photocatalytic material according to claim 1, characterized in that, The pretreated nickel foam is immersed in a solution containing Bi(NO3)3·5H2O for 3-6 minutes each time, and the pretreated nickel foam is immersed in a solution containing KI for 3-6 minutes each time.

3. The method for preparing the photocatalytic material according to claim 1, characterized in that, The concentration of Bi(NO3)3·5H2O in the solution containing Bi(NO3)3·5H2O is 40-80 mmol / L, and the concentration of KI in the solution containing KI is 40-80 mmol / L.

4. The method for preparing the photocatalytic material according to claim 1, characterized in that, The solvent for the solution containing Bi(NO3)3·5H2O is dimethylformamide, and the solvent for the solution containing KI is water.

5. The method for preparing the photocatalytic material according to claim 1, characterized in that, The microwave treatment time is 30-60 minutes, the microwave treatment temperature is 50-80℃, and the microwave treatment power is 200W-400W.

6. A photocatalytic material, characterized in that, It is prepared by the method of any one of claims 1-5.

7. The application of the photocatalytic material according to claim 6 in the removal of sulfamethazine.

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