Alkaline etching hzsm-5 molecular sieve confined iron-indium-based nanoparticle composite photocatalyst and preparation method and application thereof

Abstract

The application relates to an alkali etching HZSM-5 molecular sieve confined iron-indium-based nanoparticle composite photocatalyst and a preparation method and application thereof, and belongs to the field of advanced oxidation technology. The method comprises the following steps: sequentially performing alkali etching, hydrogen ion exchange and calcination treatment on HZSM-5 molecular sieve to obtain pretreated HZSM-5 molecular sieve; adding the pretreated HZSM-5 molecular sieve, an iron source and an indium source into a hydrophilic organic solvent and performing ultrasonic dispersion treatment to form a suspension; under stirring, adding a precipitant into the suspension, so that the iron source and the indium source are in-situ precipitated and anchored in the molecular sieve slit hole, and then washing, drying and grinding are performed to obtain the composite photocatalyst. The preparation method is used for preparing iron-indium bimetallic active species through high dispersion and strong anchoring stability of iron-indium active species in the carrier channel, excellent catalytic oxidation removal performance of typical organic pollutants is realized under low hydrogen peroxide concentration, and the cycle stability of the catalyst is improved.

Description

Technical Field

[0001] This invention relates to the field of advanced oxidation technology, specifically to an alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst, its preparation method, and its application. Background Technology

[0002] Coal gasification, as the core of modern coal chemical industry, generates large amounts of high-concentration, recalcitrant phenol-containing wastewater during production. This wastewater is extremely complex, containing not only high concentrations of phenol but also a large amount of chemically stable and highly biotoxic polyphenols (such as hydroquinone, catechol, and resorcinol) and substituted phenols. These phenolic pollutants possess stable aromatic ring structures and phenolic hydroxyl groups, exhibiting certain chemical stability, biotoxicity, and environmental persistence. Because they can interfere with the mitochondrial respiratory chain and induce neurotoxicity, they have been listed as priority pollutants and represent a key environmental bottleneck restricting the green development of the coal chemical industry.

[0003] Coal gasification wastewater often retains phenolic pollutants after traditional biochemical treatment, making it difficult to meet discharge standards. Fenton advanced oxidation technology, due to its strong oxidation capacity, has become an ideal choice for deep treatment. Heterogeneous Fenton technology effectively overcomes problems such as iron sludge pollution and difficult catalyst recovery associated with traditional methods. However, existing heterogeneous systems still face bottlenecks such as high H2O2 dosage and low iron recycling efficiency.

[0004] Fenton technology, which incorporates a light field, can significantly accelerate iron cycling, improve the efficiency of active species generation, and exhibit stronger oxidative degradation performance. However, current photocatalysts generally suffer from problems such as easy aggregation of active sites and poor cycling performance. Summary of the Invention

[0005] (a) Purpose of the invention The purpose of this invention is to overcome the limitations of the external light field enhanced Fenton system, such as easy aggregation of active sites, low H2O2 utilization, and poor cycle performance. This invention provides an alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst, its preparation method, and its application. This preparation method utilizes the high dispersion and strong anchoring stability of iron-indium active species within the pores of the support to prepare iron-indium bimetallic active species. This results in excellent catalytic oxidation removal performance for typical organic pollutants at low hydrogen peroxide concentrations, while also improving the catalyst's cycle stability.

[0006] (II) Technical Solution To address the aforementioned problems, this invention provides a method for preparing an alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst, comprising the following steps: A method for preparing an alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst includes the following steps: Step 1: The HZSM-5 molecular sieve is subjected to alkaline etching, hydrogen ion exchange and calcination treatment in sequence to obtain pretreated HZSM-5 molecular sieve; Step 2: Add the pretreated HZSM-5 molecular sieve, iron source, and indium source described in Step 1 to a hydrophilic organic solvent and disperse them by ultrasonication to form a suspension; Step 3: Under stirring conditions, the precipitant is added to the suspension described in Step 2, so that the iron source and indium source are precipitated and anchored in situ in the pores of the molecular sieve. Then, the mixture is washed, dried, and ground to obtain an alkaline-etched HZSM-5 molecular sieve confined iron-indium based nanoparticle composite photocatalyst.

[0007] Specifically, the silica-alumina ratio of the HZSM-5 molecular sieve in step 1 is 20-50; In step 2: The hydrophilic organic solvent is selected from at least one of methanol or ethanol; The iron source is selected from at least one of ferric nitrate, ferric sulfate, and ferric chloride; The indium source is selected from at least one of indium nitrate and indium sulfate; The precipitant mentioned in step 3 is selected from one of ammonium bicarbonate, sodium carbonate, and sodium bicarbonate.

[0008] Specifically, the specific conditions for alkaline etching in step 1 include: The alkaline etching solution is selected from at least one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and ammonia aqueous solution; The concentration of the alkaline etching solution is 0.1-0.4 mol / L; The solid-liquid ratio of HZSM-5 molecular sieve to the alkaline etching solution is 1:20-50; The alkaline etching temperature is 20-90℃, preferably 80-90℃; Alkali etching time is 1-4 hours; The specific conditions for hydrogen ion exchange in step 1 include: The hydrogen ion exchange solution is selected from at least one of ammonium chloride aqueous solution and ammonium sulfate aqueous solution; The concentration of the hydrogen ion exchange solution is 0.5-1.5 mol / L; The solid-liquid ratio of HZSM-5 molecular sieve to the hydrogen ion exchange solution is 1:30-50; The hydrogen ion exchange time is 6-9 hours. The specific calcination conditions described in step 1 include: The calcination atmosphere is an oxygen-rich atmosphere; The calcination temperature is 450-550℃; The heating rate is 5-10℃ / min; The calcination time is 2-4 hours.

[0009] Specifically, in the suspension described in step 2, the content of pretreated HZSM-5 molecular sieve is 0.01-0.03 g / mL; In step 2, the molar ratio of the iron source to the indium source is 1:0.05-0.2, and the ratio of the total molar amount of the iron source and the indium source to the amount of the pretreated HZSM-5 molecular sieve is 3-3.4 mmol / g. The iron source is measured in molar amounts of iron ions, and the indium source is measured in molar amounts of indium ions.

[0010] When the total molar content of metal in the metal salt solution is within the preferred range, highly dispersed iron-indium bimetallic species can be formed in the pore structure of the pretreated HZSM-5 molecular sieve. The metal salt enters the pores of HZSM-5, enhancing the absorption range of the photocatalyst for visible light, improving the electron transfer ability, and improving the degradation effect of hydroquinone.

[0011] Specifically, in step 3, the ratio of the precipitant to the pretreated HZSM-5 molecular sieve is 8.8-10.0 mmol / g, wherein the precipitant is measured in molar amounts of the precipitant compound.

[0012] Preferably, the concentration of the precipitant in step 3 is 2.9-3.1 times the total metal molar content. Based on 0.5 g of the pretreated HZSM-5 molecular sieve, the amount of the precipitant is 4.4-4.8 mmol to ensure complete synthesis of the iron-indium bimetallic active species and dispersion in the pore structure of the HZSM-5 molecular sieve, so as to ensure that hydroquinone in the wastewater can be 100% removed within 90 min.

[0013] Specifically, in step 3: The specific stirring conditions include: a stirring rate of 300-400 r / min and a stirring time of 4-10 h; The specific conditions for the grinding process include: grinding time of 10-20 minutes, and passing the ground particles through a 200-mesh sieve.

[0014] In a specific embodiment of the present invention, a method for preparing an alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst comprises the following steps: Step 1: Etch the HZSM-5 molecular sieve using 0.1-0.4 mol / L sodium hydroxide at an alkaline etching temperature of 20-90℃ for 1-4 h. Then, perform hydrogen ion exchange on the molecular sieve using a 1.0 mol / L ammonium chloride solution and calcine at 450-550℃ to stabilize the molecular sieve structure, removing adsorbed water and impurities from the surface. The silicon-to-aluminum ratio of the HZSM-5 molecular sieve is selected from 20-50. Step 2: Disperse 0.5 g of HZSM-5 molecular sieve pretreated in Step 1 in anhydrous ethanol, a hydrophilic organic solvent. At the same time, add ferric chloride and indium sulfate to the above solution. The total molar content of the metal salts added to the hydrophilic organic solvent is 1.5-1.7 mmol. The molar ratio of ferric chloride to indium sulfate is 1:0.05-0.2, calculated as iron ions and indium ions. Sonicate for 10-30 min to form a stable suspension. Step 3: Under stirring conditions, add ammonium bicarbonate to the suspension obtained in step 2 to synthesize iron-indium based nanoparticles in the channels generated after alkaline etching, and stir for 4-10 h. Step 4: Wash the suspension obtained in Step 3 with anhydrous ethanol until the supernatant is colorless, dry it in a vacuum oven at 70-85℃ for 6-10 h, grind it for 10-20 min, and pass it through a 200-mesh sieve to obtain the alkaline-etched HZSM-5 molecular sieve confined iron-indium-based nanoparticle composite photocatalyst, denoted as Fe-In@HZSM-5.

[0015] The photocatalyst can be used to activate hydrogen peroxide under external light fields and efficiently degrade recalcitrant organic pollutants in wastewater containing hydroquinone. In addition, it also shows good degradation effects on typical phenolic organic pollutants such as ferulic acid, catechol, and resorcinol, as well as antibacterial pollutants such as tetracycline.

[0016] In another aspect, the present invention provides an alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst prepared by any of the methods described above.

[0017] In another aspect, the present invention provides the application of the photocatalyst prepared by the method described in any one of the above-mentioned methods in the degradation of organic pollutants by hydrogen peroxide activated by an external light field, wherein the organic pollutants are at least one of phenolic organic pollutants and antibacterial drugs.

[0018] Specifically, the phenolic organic pollutants include at least one of hydroquinone, resorcinol, catechol, and ferulic acid; the antibacterial drug is tetracycline.

[0019] Specifically, the amount of photocatalyst added is 0.1-0.5 g / L, and the concentration of hydrogen peroxide is 0.3-1.1 mM.

[0020] Preferably, the dosage of the photocatalyst is 0.1-0.5 g / L, and the concentration of hydrogen peroxide is 0.8-0.9 mM. Under the premise of ensuring a low amount of hydrogen peroxide, hydroquinone in the wastewater can be 100% removed within 90 min.

[0021] Compared with the prior art, the present invention has the following superior effects: This invention employs a synergistic strategy combining alkaline etching and wet chemical methods. It utilizes a hydrophilic organic solvent to regulate the hydrolysis kinetics of iron and indium sources under the action of a precipitant, thereby in-situ constructing iron-indium bimetallic nanoparticles within the pores of an alkaline-etched HZSM-5 molecular sieve. This preparation method leverages the spatial confinement effect of the slit-pore structure of the molecular sieve to achieve size control and high dispersion of the iron-indium bimetallic nanoparticles, effectively solving the aggregation problem of active particles and enhancing their anchoring stability. Within the confined microenvironment of HZSM-5, the introduction of the indium component significantly broadens the visible light response range of the catalyst and accelerates the interfacial transfer of photogenerated charges, while maintaining excellent H2O2 activation rate and active species generation capacity. Under visible light enhancement, the composite catalyst photocatalyst can generate •OH, 1 O2、•O2 - h + It exhibits a wide range of reactive oxygen species, enabling multi-channel synergistic attack on typical phenolic organic pollutants such as hydroquinone, catechol, resorcinol, and ferulic acid, as well as typical antibacterial drugs such as tetracycline, demonstrating broad-spectrum, high-efficiency, and stable catalytic degradation performance. Attached Figure Description

[0022] Figure 1 These are scanning electron microscope images of the photocatalysts prepared in Comparative Examples 1, 2 and Example 1 of the present invention, where a is Comparative Example 1, b is Comparative Example 2 and c is Example 1. Figure 2 The image shown is a scanning electron microscope (SEM) image and energy-dispersive X-ray spectroscopy (EDS) image of the photocatalyst prepared in Example 1 of this invention, where a is iron and b is indium. Figure 3 These are transmission electron microscope (TEM) images of the photocatalysts prepared in Comparative Example 2 and Example 1 of the present invention, where a is Comparative Example 2 and b is Example 1; Figure 4 This is a transmission electron microscope (TEM) image of the photocatalyst Fe-In@HZSM-5 prepared in Example 1 of this invention. Figure 5 This is a high-angle annular dark-field transmission electron microscope image of the photocatalyst Fe-In@HZSM-5 prepared in Example 1 of this invention; Figure 6 The X-ray diffraction patterns are of the photocatalysts prepared in Comparative Examples 1-2 and Example 1 of this invention. Figure 7 The degradation effect of the catalysts prepared in Example 1 and Comparative Examples 2-5 of this invention on hydroquinone wastewater is shown in the figure. Figure 8 The following diagrams illustrate the degradation effect of the catalysts prepared in Examples 2-5 of this invention on hydroquinone wastewater. Figure 9The degradation effect of the catalysts prepared in Application Examples 6-8 and Application Example 2 on hydroquinone is shown in the figure. Figure 10 The graph shows the degradation effect of the catalysts prepared in Application Examples 9-11 and Application Example 2 on hydroquinone wastewater. Figure 11 The degradation effect of the catalysts prepared in Application Examples 12-15 and Application Example 2 on hydroquinone wastewater is shown in the figure. Figure 12 The graph shows the degradation effect of the catalyst prepared in Example 1 of this invention on hydroquinone wastewater under different amounts of hydrogen peroxide. Figure 13 This is a graph showing the recycling performance of the catalyst prepared in Example 1 of the present invention; Figure 14 This is a generalization diagram of the catalyst prepared in Example 1 of the present invention for degrading other pollutants; Figure 15 The steady-state concentration diagram of each active species for 30 min is shown for the catalyst prepared in Example 1 of this invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0024] The raw materials and reagents used in the embodiments and comparative examples of this invention are all conventional commercially available products; The wastewater mentioned in each embodiment of the present invention is simulated wastewater prepared by mixing the target pollutant with ultrapure water; The hydrogen peroxide reaction was activated by an external light field and carried out in a photoreactor at room temperature (25 °C).

[0025] Example 1 (1) 2 g of HZSM-5 molecular sieve (silicon-to-aluminum ratio of 25) was added to 100 mL of 0.3 mol / L sodium hydroxide aqueous solution for alkaline etching, wherein the solid-liquid ratio of HZSM-5 molecular sieve to sodium hydroxide aqueous solution was 1:50, the alkaline etching temperature was 80℃, and the alkaline etching time was 3 h; the alkaline-etched HZSM-5 molecular sieve was taken out, centrifuged to remove the supernatant, and placed in a forced-air drying oven to dry at 80℃ for 8 h. After that, the dried sample was taken out and hydrogen ion exchanged with 50 mL of 1.0 mol / L ammonium chloride aqueous solution, wherein the solid-liquid ratio of the dried sample to ammonium chloride aqueous solution was 1:25, the ion exchange time was 6 h, taken out, centrifuged to remove the supernatant, and placed in a forced-air drying oven to dry at 80℃ for 8 h. After that, the dried sample was taken out and placed in a muffle furnace, and calcined at 550℃ at a heating rate of 5℃ / min under air atmosphere for 4 hours. h stabilizes the molecular sieve structure to obtain the pretreated HZSM-5 molecular sieve; (2) Weigh 0.5 g of HZSM-5 molecular sieve pretreated in step (1), place it in a beaker containing 40 mL of hydrophilic organic solvent anhydrous ethanol, add 1.4 mmol (in terms of the molar amount of iron ions) of ferric chloride hexahydrate, and sonicate for 10 min to fully disperse the pretreated HZSM-5 molecular sieve and ferric chloride hexahydrate to form a suspension. (3) Add 0.14 mmol (in terms of the molar amount of indium ions) of indium sulfate (the indium doping amount is 10% of the iron loading amount, where the iron loading amount is based on the amount of iron ions added in step 2) to the suspension obtained in (2), sonicate for 10 min to disperse it fully, and obtain a suspension containing iron salt, indium salt and HZSM-5 molecular sieve. (4) Add 4.6 mmol of ammonium bicarbonate (based on the amount of iron ions added in step (2)) to the suspension containing iron salt, indium salt and HZSM-5 molecular sieve obtained in (3), and stir for 8 h at a stirring rate of 350 r / min to obtain a mixed system; (5) The mixture obtained in (4) was washed with anhydrous ethanol until the supernatant was colorless, dried in a vacuum oven at 80°C for 8 h, ground for 10 min, and passed through a 200-mesh sieve to obtain the alkaline-etched HZSM-5 molecular sieve confined iron-indium-based nanoparticle composite photocatalyst, denoted as Fe-In@HZSM-5.

[0026] Examples 2-4 The catalyst preparation process in Examples 2-4 is the same as that in Example 1, except that in step (1), the concentrations of the sodium hydroxide aqueous solution used to etch the HZSM-5 molecular sieve are 0.1 mol / L, 0.2 mol / L and 0.4 mol / L, respectively.

[0027] Examples 5-7 The catalyst preparation process in Examples 5-7 is the same as that in Example 1, except that in step (1), the etching temperatures of HZSM-5 molecular sieve are 20, 50 and 90°C respectively.

[0028] Examples 8-10 The catalyst preparation process in Examples 8-10 is the same as that in Example 1, except that in step (1), the etching time of HZSM-5 molecular sieve is 1, 2 and 4 hours respectively.

[0029] Examples 11-13 The catalyst preparation process in Examples 11-13 is the same as that in Example 1, except that in step (3), the indium doping amount is 5%, 15% and 20% of the iron loading.

[0030] Comparative Example 1 Compared with Example 1, steps (2) to (5) were omitted in Comparative Example 1, and only the HZSM-5 molecular sieve was subjected to calcination pretreatment as a blank control.

[0031] Comparative Example 2 (1) Weigh 0.5 g of the original HZSM-5 molecular sieve (silicon-aluminum ratio of 25), place it in a beaker containing 40 mL of hydrophilic organic solvent anhydrous ethanol, and add 1.4 mmol (in terms of the molar amount of iron ions) of ferric chloride hexahydrate. Sonicate for 10 min to fully disperse the pretreated HZSM-5 molecular sieve and ferric chloride hexahydrate to form a suspension. (2) Add 4.6 mmol of ammonium bicarbonate to the suspension of iron salt and HZSM-5 molecular sieve obtained in (1) and stir for 8 h at a stirring rate of 350 r / min to obtain a mixed system; (3) The mixture obtained in (2) was washed with anhydrous ethanol until the supernatant was colorless, dried in a vacuum oven at 80°C for 8 h, ground for 10 min, and passed through a 200-mesh sieve to obtain the catalyst.

[0032] Comparative Example 3 Compared with Example 1, step (3) is omitted in Comparative Example 3.

[0033] Comparative Example 4 (1) Weigh 10 g of urea and put it into a porcelain boat. Place the boat into a muffle furnace and calcine it at 500°C for 2 h in air atmosphere at a heating rate of 5°C / min to obtain a stable graphitic carbon nitride substrate; (2) Weigh 0.5 g of graphitic carbon nitride calcined in step (1) and place it in a beaker containing 40 mL of hydrophilic organic solvent anhydrous ethanol. At the same time, add 1.4 mmol (in terms of the molar amount of iron ions) of ferric chloride hexahydrate and sonicate for 10 min to fully disperse the graphitic carbon nitride and ferric chloride hexahydrate to form a suspension. (3) Add 0.14 mmol (in terms of the molar amount of indium ions) of indium sulfate (indium doping amount is 10% of the iron loading) to the suspension obtained in (2), and sonicate for 10 min to disperse it fully, so as to obtain a suspension containing iron salt, indium salt and graphite phase carbon nitride. (4) Add 4.6 mmol of ammonium bicarbonate to the suspension containing iron salt, indium salt and graphite phase carbon nitride obtained in (3), and stir for 8 h at a stirring rate of 350 r / min to obtain a mixed system; (5) The mixture obtained in (4) was washed with anhydrous ethanol until the supernatant was colorless, dried in a vacuum oven at 80°C for 8 h, ground for 10 min, and passed through a 200-mesh sieve to obtain the catalyst.

[0034] Comparative Example 5 (1) Weigh 0.5 g of HZSM-5 molecular sieve pretreated in step (1) of Example 1; place it in a beaker containing 40 mL of deionized water, and add 1.4 mmol (in terms of iron ion molar amount) of ferric chloride hexahydrate and 0.14 mmol (in terms of indium ion molar amount) of indium sulfate (indium doping amount is 10% of iron loading amount), and sonicate for 10 min to fully disperse the pretreated HZSM-5 molecular sieve, ferric chloride hexahydrate and indium sulfate to form a suspension; (2) Slowly add 2 mol of sodium hydroxide aqueous solution to the suspension obtained in (1) to adjust the pH to 10, and stir for 30 min at a stirring rate of 350 r / min to obtain a mixed precursor suspension; (3) After thoroughly stirring the suspension, transfer it to a 100 mL high-pressure reactor lined with polytetrafluoroethylene and seal it. Place the reactor in an oven at 100℃ for 12 h. (4) After the reaction is complete, the reactor is allowed to cool naturally to room temperature. The supernatant is poured out, and the precipitate is washed three times with deionized water and anhydrous ethanol. It is then dried in a vacuum oven at 80°C for 8 h, ground for 10 min, and passed through a 200-mesh sieve to obtain the catalyst.

[0035] The catalysts provided in each embodiment and comparative example were characterized, with Example 1 and Comparative Examples 1 and 2 being typical examples. The characterization results are shown in [reference needed]. Figure 1-6 Specifically, it includes: like Figure 1As shown in the figure, Comparative Examples 1 and 2 have hexagonal prism shapes and are basically the same. However, in Example 1, compared to Comparative Examples 1-2, the surface structure of the hexagonal prism is etched, but its overall framework is not destroyed. This conclusion is... Figure 6 This was further confirmed in the X-ray diffraction pattern. Figure 2 As can be seen, the uniform distribution of iron and indium elements, without any significantly large local agglomerations, proves that iron and indium elements are highly dispersed within the molecular sieve and no obvious agglomeration was observed. Figure 3 visible, Figure 3 b compared to Figure 3 a) The molecular sieve exhibits mesoporous characteristics, proving that alkaline etching can create mesoporous structures in the molecular sieve. For example... Figure 4 As shown, the iron-indium-based nanoparticles have a particle size of approximately 5 nm. Since the size of quantum dots is approximately 1-10 nm, the iron-indium-based nanoparticles meet the size requirements of quantum dots, proving that iron-indium-based quantum dots have been successfully synthesized. Figure 5 As shown, the iron-indium quantum dots are confined in the slit holes of the pretreated HZSM-5.

[0036] The hydroquinone removal performance of the catalysts provided in each embodiment and comparative example was tested, specifically including: Application Example 1 The catalysts prepared in Comparative Examples 2, 3, 4, and 5, and the Fe-In@HZSM-5 catalyst prepared in Example 1, were used for external light field activation of hydrogen peroxide to degrade hydroquinone wastewater. Specifically, the following methods were employed: The catalyst and hydrogen peroxide were added to 50 mL of hydroquinone wastewater with an initial concentration of 20 mg / L to obtain a reaction mixture. The light irradiation intensity was 25 mW / cm². 2 The catalyst dosage in the mixed system was 0.4 g / L, the hydrogen peroxide concentration was 0.9 mM, and the initial pH of 50 mL of hydroquinone wastewater with an initial concentration of 20 mg / L was 6.64. The reaction was carried out at room temperature (25°C) for 30 min.

[0037] Application Example 2-15 Application Examples 2-15, using the catalysts provided in Examples 1-13 and Comparative Example 2 respectively, are used for the external light field activation of hydrogen peroxide to degrade hydroquinone wastewater, specifically including: The catalyst in Application Example 2-15 was used under the same conditions as in Application Example 1 for the external light field activation of hydrogen peroxide to degrade hydroquinone in wastewater. The difference was that in Application Example 2-15, 50 mL of wastewater with an initial concentration of 10 mg / L hydroquinone was treated under the following conditions: catalyst dosage of 0.3 g / L, hydrogen peroxide concentration of 1.1 mM, and reaction time of 90 min.

[0038] See Figure 7-11 The test results show that: like Figure 7 As shown, in Application Example 1, the catalyst provided in Example 1 achieved a 100% removal rate of hydroquinone after reacting for 30 min, while the catalyst provided in Comparative Example 2 only achieved a 66.70% removal rate, and the catalyst provided in Comparative Example 3 only achieved an 88.7% removal rate. The catalysts in Comparative Examples 4 and 5 had removal efficiencies of only 60.35% and 72.10%, respectively.

[0039] It is evident that the alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst exhibits significant advantages in activating H2O2 degradation of hydroquinone under external light field. By employing an alkaline etching pretreatment followed by a hydrophilic organic solvent-mediated wet chemical method, the slow hydrolysis of the precipitant in the hydrophilic organic solvent enables uniform molecular-level dispersion and controlled hydrolysis of indium and iron ions in the precursor solution. This ensures that the active components exist in a stable solvated state in the impregnation solution, laying the foundation for the "in-situ construction" and strong anchoring of indium and iron active centers within the hierarchical channels of the molecular sieve. The spatial confinement effect of the molecular sieve channels promotes the high dispersion of the iron-indium bimetallic compound in the form of quantum dots. The spatial proximity between active sites and the lattice doping of indium exhibit a significant electronic synergistic effect, significantly enhancing the absorption capacity of visible light and the activation efficiency of H2O2. In addition, indium doping effectively modulates the electron density of iron species and accelerates the valence state cycle of iron ions. At the same time, the electron acceptor effect of the confined microenvironment and the synergistic effect of bimetals complement each other, further optimizing the separation efficiency of photogenerated carriers and enhancing the generation efficiency of reactive oxygen species. Ultimately, this improves the broad-spectrum degradation performance and cycle stability of the photocatalyst under low hydrogen peroxide consumption.

[0040] like Figure 8-11 As shown, in application examples 2-5, refer to the appendix Figure 8 Within 60 minutes, the removal rate of hydroquinone can reach over 90%. In application examples 2 and 6-8, the control group... Figure 9 When the alkaline etching temperature is 20-90℃, the removal rate of hydroquinone reaches over 83% within 45 minutes. Especially when the alkaline etching temperature is 80-90℃, the removal rate of hydroquinone reaches over 93% within 45 minutes. (See attached figure) Figure 10 Application Examples 9-11 showed a removal rate of over 81% for hydroquinone within 30 minutes, while Application Example 2 showed a removal rate of over 91% within 30 minutes; (See attached control). Figure 11 Application Examples 2 and 12-14 achieved a removal rate of over 97% for hydroquinone within 60 minutes, while the catalyst provided in Comparative Example 2 only achieved a removal rate of about 86% for hydroquinone within 60 minutes.

[0041] Application Examples 16-18 The Fe-In@HZSM-5 catalyst prepared in Example 1 was used for external light field activation of hydrogen peroxide to degrade hydroquinone wastewater, specifically including: Fe-In@HZSM-5 catalyst and hydrogen peroxide were added to 50 mL of hydroquinone wastewater with an initial concentration of 20 mg / L to obtain a reaction mixture. The light irradiation intensity was 25 mW / cm². 2 The catalyst dosage in the mixed system was 0.4 g / L, the initial pH of 50 mL of hydroquinone wastewater with an initial concentration of 20 mg / L was 6.64, and the reaction was carried out at room temperature (25℃) for 50 min.

[0042] The difference in Application Examples 16-18 is that the hydrogen peroxide concentrations are 0.5, 0.7, and 1.1 mM, respectively.

[0043] The results are as follows Figure 12 As shown, the catalyst can still achieve a removal rate of over 90% for hydroquinone after 50 min of reaction at hydrogen peroxide concentrations of 0.5-1.1 mM, demonstrating a high removal rate for hydroquinone even at low hydrogen peroxide concentrations.

[0044] Application Example 19 The Fe-In@HZSM-5 catalyst prepared in Example 1 was used for the degradation of hydroquinone wastewater by hydrogen peroxide activated by an external light field. The degradation conditions were basically the same as those in Application Example 1. The difference was that in Application Example 19, after each reaction, the catalyst was separated and recovered from the reaction system, cleaned and dried, and then put back into the next reaction. The above steps were repeated six times to examine the reusability of the catalyst.

[0045] The results are as follows Figure 13 As shown, the catalyst still achieved a removal rate of 87.57% for hydroquinone after 30 min of reaction during six cycles of use.

[0046] Application Examples 20-23 The Fe-In@HZSM-5 catalyst prepared in Example 1 was used to activate hydrogen peroxide in an external light field to degrade organic pollutant wastewater. The degradation conditions were basically the same as those in Application Example 1, except that the target pollutants in Application Examples 20-23 were resorcinol, catechol, tetracycline, and ferulic acid, respectively.

[0047] The results are as follows Figure 14 As shown, within 30 minutes, the catalyst achieved a 100% removal rate for tetracycline and ferulic acid, a removal rate of over 90% for catechol, and a removal rate of over 70% for resorcinol.

[0048] The steady-state concentration of active species in the catalyst was tested, specifically including: The Fe-In@HZSM-5 catalyst prepared in Example 1 was used to activate the hydrogen peroxide system under an external light field, and benzoic acid, furfuryl alcohol and p-benzoquinone were used as probe molecules to investigate the steady-state concentration of active species generated by Fe-In@HZSM-5.

[0049] Experimental results are as follows Figure 15 As shown, the Fe-In@HZSM-5 catalyst, when activated by an external light field, produces a large amount of hydrogen peroxide. 1 O2 and •O2 - And a small amount of •OH. The results show that there are free radical and non-free radical pathways in this system, which can utilize a variety of reactive oxygen species to achieve efficient removal of pollutants.

[0050] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for preparing an alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst, characterized in that, Includes the following steps: Step 1: The HZSM-5 molecular sieve is subjected to alkaline etching, hydrogen ion exchange and calcination treatment in sequence to obtain pretreated HZSM-5 molecular sieve; Step 2: Add the pretreated HZSM-5 molecular sieve, iron source, and indium source described in Step 1 to a hydrophilic organic solvent and disperse them by ultrasonication to form a suspension; Step 3: Under stirring conditions, the precipitant is added to the suspension described in Step 2, so that the iron source and indium source are precipitated and anchored in situ in the pores of the molecular sieve. Then, the mixture is washed, dried, and ground to obtain an alkaline-etched HZSM-5 molecular sieve confined iron-indium based nanoparticle composite photocatalyst.

2. The preparation method according to claim 1, characterized in that, The silica-alumina ratio of the HZSM-5 molecular sieve mentioned in step 1 is 20-50; In step 2: The hydrophilic organic solvent is selected from at least one of methanol or ethanol; The iron source is selected from at least one of ferric nitrate, ferric sulfate, and ferric chloride; The indium source is selected from at least one of indium nitrate and indium sulfate; The precipitant mentioned in step 3 is selected from one of ammonium bicarbonate, sodium carbonate, and sodium bicarbonate.

3. The preparation method according to claim 1, characterized in that, The specific conditions for alkaline etching in step 1 include: The alkaline etching solution is selected from at least one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and ammonia aqueous solution; The concentration of the alkaline etching solution is 0.1-0.4 mol / L; The solid-liquid ratio of HZSM-5 molecular sieve to the alkaline etching solution is 1:20-50; The alkaline etching temperature is 20-90℃; Alkali etching time is 1-4 hours; The specific conditions for hydrogen ion exchange in step 1 include: The hydrogen ion exchange solution is selected from at least one of ammonium chloride aqueous solution and ammonium sulfate aqueous solution; The concentration of the hydrogen ion exchange solution is 0.5-1.5 mol / L; The solid-liquid ratio of HZSM-5 molecular sieve to the hydrogen ion exchange solution is 1:30-50; The hydrogen ion exchange time is 6-9 hours. The specific calcination conditions described in step 1 include: The calcination atmosphere is an oxygen-rich atmosphere; The calcination temperature is 450-550℃; The heating rate is 5-10℃ / min; The calcination time is 2-4 hours.

4. The preparation method according to claim 1, characterized in that, In the suspension described in step 2, the content of pretreated HZSM-5 molecular sieve is 0.01-0.03 g / mL; In step 2, the molar ratio of the iron source to the indium source is 1:0.05-0.2, and the ratio of the total molar amount of the iron source and the indium source to the amount of the pretreated HZSM-5 molecular sieve is 3-3.4 mmol / g. The iron source is measured in molar amounts of iron ions, and the indium source is measured in molar amounts of indium ions.

5. The preparation method according to claim 1, characterized in that, In step 3, the ratio of the precipitant to the pretreated HZSM-5 molecular sieve is 8.8-10.0 mmol / g, wherein the precipitant is measured in molar amounts of the precipitant compound.

6. The preparation method according to claim 1, characterized in that, In step 3: The specific stirring conditions include: a stirring rate of 300-400 r / min and a stirring time of 4-10 h; The specific conditions for the grinding process include: grinding time of 10-20 minutes, and passing the ground particles through a 200-mesh sieve.

7. The alkaline-etched HZSM-5 molecular sieve-confined iron-indium based nanoparticle composite photocatalyst prepared by the method according to any one of claims 1-6.

8. The application of the photocatalyst prepared by the method according to any one of claims 1-6 in the degradation of organic pollutants by hydrogen peroxide activated by an external light field, characterized in that, The organic pollutant is at least one of phenolic organic pollutants or antibacterial drugs.

9. The application according to claim 8, characterized in that, The amount of photocatalyst added is 0.1-0.5 g / L, and the concentration of hydrogen peroxide is 0.3-1.1 mM.

10. The application according to claim 9, characterized in that, The hydrogen peroxide concentration is 0.7-0.9 mM.

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