A polyacrylamide aerogel loaded with high-entropy spinel ferrite catalyst, and a preparation method and application thereof

Abstract

This invention discloses a polyacrylamide aerogel supported on a high-entropy spinel ferrite catalyst, its preparation method, and its applications. This invention uses a hydrothermal method to prepare Cu... 1 / 2 Zn 1 / 2 Fe 2 / 3 Co 2 / 3Ni 2 / 3 O4 high-entropy ferrite catalyst (HEO) was supported on polyacrylamide aerogel to form a composite catalyst (PAM@HEO). The performance of this catalyst in photocatalytic degradation of dyes was evaluated using simulated visible light, and the reaction mechanism of the most effective photocatalytic degradation of methylene blue was investigated. This invention utilizes the synergistic catalytic effect of ferrite and polymer aerogel to effectively promote photocatalytic reactions, thereby achieving environmentally friendly pollutant degradation. The production process is simple, does not introduce various toxic or harmful organic substances, is non-toxic and harmless during use, has a catalyst recovery efficiency exceeding 95%, and features significant degradation effects without generating secondary pollution. The preparation method only involves processes such as dissolution, hydrothermal treatment, filtration, and calcination, making it extremely suitable for industrial-scale mass production.

Description

Technical Field

[0001] This invention relates to the fields of photocatalysis, spinel ferrite, and pollutant degradation, specifically to a polyacrylamide aerogel supported on a high-entropy spinel ferrite catalyst, its preparation method, and its application in the efficient degradation of dyes. Background Technology

[0002] Industrial wastewater contains large amounts of dyes, which can cause serious pollution and even threaten human survival and health when discharged into the environment. Methylene blue (MB) is a commonly used chemical dye in textile industry wastewater. It has azo and nitro groups and other difficult-to-decompose chemical structures, making it carcinogenic and toxic. Combined with the inhibitory effect of antibiotics on microorganisms, traditional processes are difficult to remove effectively. Advanced oxidation technologies are usually required to degrade methylene blue into harmless products. In recent years, photocatalysis technology has been considered a promising method for degrading pollutants due to its advantages such as no risk of secondary pollution, environmental sustainability, and environmentally friendly degradation performance.

[0003] In the past, oxides based on transition metals (Fe, Co, Ni) have been studied as alternative catalysts to noble metals due to their abundance, low cost, and high catalytic activity. Among them, spinel ferrites have attracted much attention due to their advantages such as high catalytic efficiency, simple preparation, and easy recycling. For example, the low-cost spinel ferrite Fe3O4 has been widely reported to have photocatalytic activity and has been applied to the photocatalytic degradation of dyes. In addition, its excellent stability and magnetism are beneficial for the recycling of wastewater through photocatalytic degradation. However, due to the large specific surface area and narrow spectral response of Fe3O4, its photocatalytic performance is still not ideal. Summary of the Invention

[0004] To enhance photocatalytic performance, a synergistic strategy combining high entropy and aerogel loading was employed. First, by introducing multiple principal components to form high-entropy spinel oxide, the high configurational entropy induces lattice distortion, band structure modulation, and abundant defect sites, effectively broadening the light absorption range and suppressing carrier recombination, thereby significantly enhancing intrinsic catalytic activity. Second, loading the high-entropy oxide onto polyacrylamide aerogel with a three-dimensional network structure not only utilizes its ultra-high porosity to achieve high dispersion and stable anchoring of active components but also enriches reactants through surface functional groups, further improving the overall catalytic efficiency and stability of the composite material.

[0005] Based on this, the present invention designs and prepares a polyacrylamide aerogel-supported high-entropy spinel ferrite composite catalyst (PAM@HEO), aiming to further improve photocatalytic performance through the synergistic effect of the support and active components.

[0006] The technical solution of this invention is: a method for preparing polyacrylamide aerogel supported on a high-entropy spinel ferrite catalyst, comprising the following steps: Prepare an aqueous solution of acrylamide using boiled deionized water, and purge with nitrogen to remove residual dissolved oxygen; The solution was stirred at a constant temperature of 20-60℃, and potassium persulfate (K2S2O8) and accelerator tetramethylethylenediamine were added to carry out an acrylamide condensation reaction until the solution became a viscous polyacrylamide hydrogel. High-entropy spinel ferrite catalyst powder was added to the hydrogel, and the mixture was kept warm and stirred before being freeze-dried to obtain a polyacrylamide hydrogel loaded with high-entropy spinel ferrite catalyst. The general formula of the high-entropy spinel ferrite catalyst is Cu. 1 / 2 Zn 1 / 2 Fe 2 / 3 Co 2 / 3 Ni 2 / 3 O4, wherein the catalyst particles have a size of 50-200 nm.

[0007] Furthermore, the high-entropy spinel ferrite catalyst is prepared using the following steps: Weigh ferric nitrate, nickel nitrate, cobalt nitrate, zinc acetate, and copper nitrate in a molar ratio of 1:1:1:0.76:0.76, dissolve and mix them in deionized water to obtain a metal ion salt solution. Prepare a potassium hydroxide solution by slowly adding it dropwise to a metal ion salt solution and stirring until a solution with pH=7 is obtained. The solution was transferred to a hydrothermal reactor for hydrothermal reaction. After natural cooling, the mixture was filtered, and the filter residue was dried to obtain precursor powder. The precursor powder was ground and then calcined in a high-temperature furnace at 700~900℃ to obtain a high-entropy spinel ferrite catalyst.

[0008] Furthermore, the precursor powder is ground and then calcined in a high-temperature furnace at 800°C to obtain a high-entropy spinel ferrite catalyst.

[0009] Furthermore, the hydrothermal reaction temperature is 220℃ and the time is 24h.

[0010] Furthermore, the heating rate during calcination is 5℃ / min, the cooling rate is 5℃ / min, and the holding time is 2h.

[0011] Furthermore, the precursor powder is ground and then calcined in a high-temperature furnace at 800°C to obtain a high-entropy spinel ferrite catalyst.

[0012] Furthermore, the added potassium persulfate (K2S2O8) is freshly prepared potassium persulfate, and the amount added is 1-1.5%wt of polyacrylamide.

[0013] Furthermore, the added accelerator tetramethylethylenediamine (TEMED) has a molar ratio of 1:1 to potassium persulfate.

[0014] Furthermore, the acrylamide condensation reaction process requires constant temperature stirring at 50°C for more than 30 minutes, and the stirring speed should be increased and the reaction vessel sealed.

[0015] Furthermore, the hydrogel was freeze-dried in a vertical freeze dryer under conditions of -60°C and vacuum for 24 hours.

[0016] The polyacrylamide hydrogel supported on a high-entropy spinel ferrite catalyst is used for the degradation of dyes and antibiotics under light irradiation without the addition of oxidants.

[0017] Compared with the prior art, the present invention has the following advantages: The present invention provides a method for improving the ability of spinel ferrite to degrade dyes under visible light using a high-entropy strategy: (1) This study successfully prepared a supported high-entropy spinel ferrite catalyst Cu using a hydrothermal method. 1 / 2 Zn 1 / 2 Fe 2 / 3Co 2 / 3 Ni 2 / 3 O4 polyacrylamide aerogel catalyst exhibits significant selective photocatalytic activity towards dyes such as methylene blue, with a degradation efficiency significantly higher than that of single-component oxides.

[0018] (2) The catalyst still maintains good photocatalytic activity after multiple cycles, with a cycle performance of 96.63%.

[0019] (3) By adopting a high-entropy strategy, a variety of metal elements are combined to form a high-entropy spinel ferrite catalyst, which makes full use of the high-entropy effect, strong lattice distortion effect, slow diffusion effect and cocktail effect, and significantly improves the photocatalytic performance of the catalyst.

[0020] (4) High-entropy spinel ferrite catalysts contain metal ions in multiple valence states, which provide more reaction sites and charge transfer pathways for catalytic reactions, further improving catalytic activity.

[0021] (5) The polyacrylamide (PAM) aerogel carrier has amide groups (-CONH2) on its surface that can coordinate with metal ions in high-entropy spinel ferrite, achieving in-situ anchoring and high dispersion of active components and preventing particle aggregation. The polar polymer structure of PAM is conducive to building a stable interface and improving electron transport capacity, thereby promoting the migration and separation of photogenerated electrons, inhibiting electron-hole recombination, and ultimately improving photocatalytic degradation efficiency. PAM can also efficiently enrich cationic pollutants in water through hydrogen bonding and other interactions. This "anchoring-enrichment" synergistic effect optimizes both the exposure of active sites and the concentration of local reactants in the composite catalyst, significantly improving the photocatalytic degradation efficiency.

[0022] (6) The three-dimensional cross-linked network of aerogel has good mechanical flexibility and plasticity. The PAM@HEO composite catalyst overcomes the shortcomings of traditional powder catalysts, such as easy agglomeration and easy loss, and improves the recyclability of the catalyst. At the same time, the framework structure of aerogel significantly broadens the application scenarios of the catalyst.

[0023] (7) This invention uses visible light as an energy source, avoiding the secondary pollution problems that may occur in traditional chemical oxidation methods. The high-entropy spinel ferrite catalyst supported on polyacrylamide aerogel has good magnetic properties and plasticity, is easy to recycle and reuse, and is in line with the concept of green environmental protection.

[0024] (8) High-entropy spinel ferrite catalysts supported on polyacrylamide aerogels are prepared by hydrothermal methods and other processes. The operation is simple, the cost is low, and it is easy to achieve large-scale production. Attached Figure Description

[0025] Figure 1 XRD patterns of high-entropy spinel ferrite HEO and polyacrylamide aerogel-supported high-entropy spinel ferrite catalyst PAM@HEO synthesized under different conditions, and their corresponding spinel ferrite standard cards PDF#10-0325NiFe2O4 and PDF#26-1136Fe3O4. Figure 2 SEM image and EDS elemental distribution diagram of high-entropy spinel oxide HEO; Figure 3 (a) shows the concentration changes of HEO and PAM@HEO in the photocatalytic degradation of methylene blue. t The figure shows the C0 graph, which uses the most traditional ferrite catalyst NFO (NiFe2O4) in the industry as a comparison. (b) is the corresponding degradation rate change graph, (c) is the pseudo-first-order kinetic analysis graph of photocatalytic degradation, and (d) is the recycling performance test of PAM@HEO. Figure 4 For four groups (Co) 0.4 Ni 0.2 Zn0.2 Cu 0.2 Fe2O4 powder has almost no catalytic degradation effect on methylene blue in the absence of light and persulfate (PDS); Figure 5 The effect of high-entropy spinel ferrite catalyst supported on polyacrylamide aerogel on the catalysis of methyl orange, Congo red, ciprofloxacin and sodium sulfadiazine in a dark chamber. Figure 6 The effects of HEO and PAM@HEO on the photocatalytic degradation of methyl orange, Congo red, and aromatic cyclic antibiotics. Detailed Implementation

[0026] The present invention will be further described below with reference to embodiments and accompanying drawings. However, the following description is only for some exemplary examples of the present invention and is used only to illustrate the present invention, and is not intended to limit the scope of the present invention.

[0027] Example 1

[0028] A highly efficient dye-degrading polyacrylamide aerogel-supported high-entropy spinel ferrite catalyst and its preparation method thereof, comprising the following steps: (1) Preparation of high-entropy oxides: Accurately weigh 0.023 mol Fe(NO3)3*9H2O (ferric nitrate nonahydrate), 0.023 mol Ni(NO3)2*6H2O (nickel nitrate hexahydrate), 0.023 mol Co(NO3)3*6H2O (cobalt nitrate hexahydrate), 0.0175 mol Zn(C2H3O2)2*2H2O (zinc acetate dihydrate), and 0.0175 mol Cu(NO3)2*3H2O (copper nitrate trihydrate). After thorough mixing and dissolution, a metal salt solution is obtained. In this example, Zn(C2H3O2)2H2O is selected. The precise weighing of H3O2)2*2H2O (zinc acetate dihydrate) is more accurate and has less error than that of Zn((NO3)2*6H2O, because Zn((NO3)2*6H2O is hygroscopic and difficult to weigh precisely. 0.3 mol of potassium hydroxide was weighed to prepare a solution, which was then added dropwise to the metal salt solution at approximately 1 ml / min with stirring. In this example, the pH of the mixed solution was 7.0. The mixed solution was transferred to a high-pressure hydrothermal reactor with a PTFE liner and heated for 24 hours. After natural cooling, it was filtered and dried to obtain the precursor powder (Cu). 1 / 2 Zn 1 / 2 Fe 2 / 3 Co 2 / 3 Ni 2 / 3 ) x O y The precursor powder was ground and then calcined in a high-temperature furnace. The precursor powder was calcined at three different temperatures—700℃, 800℃, and 900℃—for 2 hours each, yielding the product Cu. 1 / 2Zn 1 / 2 Fe 2 / 3 Co 2 / 3 Ni 2 / 3 O4, the products calcined at different temperatures were named HEO-700, HEO-800 and HEO-900, respectively.

[0029] (2) Preparation of polyacrylamide aerogel supported on high-entropy spinel ferrite catalyst: An acrylamide aqueous solution with a concentration of 1 mol / L was prepared using boiled deionized water. The solution was purged with nitrogen to remove residual dissolved oxygen. The solution was stirred at 50℃, and potassium persulfate (K2S2O8) was added in an amount of 1-1.5% wt of polyacrylamide. After the potassium persulfate was stirred evenly, tetramethylethylenediamine (TEMED), a promoter with a potassium persulfate molar ratio of 1:1, was added and stirred thoroughly. The solution was stirred at 50℃ for 30 min until it became a viscous polyacrylamide hydrogel. High-entropy spinel ferrite catalyst powder was added to the hydrogel, and the mixture was kept warm and stirred to obtain a polyacrylamide hydrogel supported on high-entropy spinel ferrite catalyst. The hydrogel was poured into a mold, and the mold and the mixture were freeze-dried in a vertical freeze dryer at -60℃ and under vacuum for 24 h to obtain a high-entropy spinel ferrite-supported aerogel composite catalyst (PAM@HEO).

[0030] In this embodiment, boiling deionized water and nitrogen purging provide dual deoxygenation, preventing trace amounts of oxygen in the water from terminating the acrylamide condensation reaction. An inert gas is then introduced. It can also form a nitrogen protective shield above the liquid surface, completely isolating external air and providing an absolutely oxygen-free environment for subsequent free radical reactions. The solution is stirred at a constant temperature of 50℃ for 30 minutes to achieve a suitable viscosity for the polyacrylamide hydrogel after the acrylamide condensation reaction, allowing the acrylamide to reach an appropriate degree of cross-linking. This facilitates the uniform dispersion of the high-entropy spinel ferrite catalyst powder into the polymer cross-linked network of the polyacrylamide hydrogel. If the stirring temperature is increased or the stirring time is prolonged, the viscosity of the polyacrylamide hydrogel becomes too high, making it difficult for the high-entropy spinel ferrite catalyst powder to disperse uniformly within it. Conversely, if the stirring temperature is decreased or the stirring time is shortened, the viscosity of the polyacrylamide hydrogel becomes too low, making it difficult for the polyacrylamide hydrogel to solidify and form a clump, causing the high-entropy spinel ferrite catalyst powder to settle and clump together, significantly reducing dispersion and contact area.

[0031] In this embodiment, Cu 2+ Zn 2+ Fe 3+ Co 3+ Ni 3+The molar ratio of the salt ions is the same as the stoichiometric ratio of the divalent and trivalent metal ions in the general chemical formula of spinel, M3O4. The stoichiometric ratio of the divalent and trivalent metal ions is 1:2, with the same stoichiometric ratio for each divalent metal ion and the same stoichiometric ratio for each trivalent metal ion. Therefore, the metal salt solution contains five metal ions: Fe... 3+ Ni 3+ Co 3+ Zn 2+ Cu 2+ The molar ratio is 1.00:1.00:1.00:0.76:0.76. Therefore, the molar percentages of the five components in the metal salt solution are as follows: Fe(NO3)3*9H2O: 7.233%, Ni(NO3)2*6H2O: 7.233%, Co(NO3)3*6H2O: 7.233%, Zn(C2H3O2)2*2H2O: 5.503%, and Cu(NO3)2*3H2O: 5.503%.

[0032] In this embodiment, the pH value of the solution is adjusted by potassium hydroxide, and Fe is complexed by hydroxide ions. 3+ Ni 3+ Co 3+ Zn 2+ Cu 2+ The hydrothermal reaction allows metal oxide crystal cells to grow in a solution under high temperature and pressure. These cells gradually aggregate to form metal oxide precipitates. The reaction takes place in a mixed solution, allowing the oxides to crystallize directly from the solution, ensuring accurate stoichiometry and uniformity of the product composition. The hydrothermal method is mild, does not easily form hard agglomerates, and produces products with a particle size of approximately 100 nm that are uniformly distributed, making it suitable for polymer loading. Compared to particles with a diameter of 200 nm, these particles are more easily dispersed uniformly in gels.

[0033] The reaction equations for the formation of Fe2O3, Ni2O3, Co2O3, ZnO, and CuO from Fe(NO3)3, Ni(NO3)2, Co(NO3)3, Zn(C2H3O2)2, and Cu(NO3)2 are as follows: 2Fe(NO3)3 + 6KOH → Fe2O3 + 6KNO3 + 3H2O; The ratio of potassium hydroxide to metal salt is 3; 4Ni(NO3)2 + 8KOH + O2 → 2Ni2O3 + 8KNO3 + 4H2O; The ratio of potassium hydroxide to metal salt is 2; 2Co(NO3)3 + 6KOH → Fe2O3 + 6KNO3 + 3H2O; The ratio of potassium hydroxide to metal salt is 3; Zn(C2H3O2)2 + 2KOH → ZnO + 2KC2H3O2 + H2O; The ratio of potassium hydroxide to metal salt is 2; Cu(NO3)2 + 2KOH → CuO + 2KNO3 + H2O; The ratio of potassium hydroxide to metal salt is 2; Theoretically, when the five metal ions are prepared into a high-entropy material according to the molar ratio in the high-entropy material of this embodiment, when the potassium hydroxide is at least 0.254 mol, it can combine with enough metal salts to reduce impurities; In this embodiment, the pH value of the solution is adjusted by potassium hydroxide, and Fe is complexed by hydroxide ions. 3+ Ni 3+ Co 3+ Zn 2+ Cu 2+ Through a hydrothermal reaction, metal oxide crystal cells are grown in the solution under high temperature and high pressure, and the crystal cells gradually aggregate to form metal oxide precipitates.

[0034] Results Analysis: Characterization of the Catalyst The results show that high-entropy spinel ferrite (HEO) can be successfully prepared by calcination at 800℃. The characteristic peaks of the HEO samples are located at 30.31°, 35.71°, 36.98°, 42.95°, and 57.34°, respectively. These peaks correspond to the (220), (311), (222), (400), and (511) crystal planes, respectively. The characteristic peaks of the PAM@HEO samples are located at 30.20°, 35.59°, 36.69°, 42.64°, and 57.21°, respectively. These peaks correspond to the (220), (311), (400), (511), and (440) crystal planes, respectively. XRD results indicate that homogeneous high-entropy spinel oxides were successfully synthesized by hydrothermal method under these conditions. The supported PAM@HEO aerogel composite catalyst still maintains the crystal structure of HEO.

[0035] Figure 2 The SEM image (a) shows that the synthesized catalyst has a relatively dense structure and no obvious agglomeration, indicating that the material has good dispersibility, which lays the foundation for subsequent material performance improvement.

[0036] Example 2

[0037] Weigh 50 mg of the catalyst prepared in Example 1 and pour it into a quartz glass reaction flask (the quartz glass reaction flask allows light to penetrate and reach the reaction system; it does not react with the reactants, ensuring the purity and controllability of the reaction). Add 100 ml of the 10 ppm solution to be degraded and shake well. Place the reaction flask in a dark chamber for static adsorption for 12 h, then transfer it to a photocatalytic device (PerfectLight, PCX50CDiscover) for photocatalytic reaction. Stirring is turned on simultaneously. The photocatalytic degradation process and sampling are carried out in a constant temperature circulating water environment at 25℃. Take 3-4 mL of the test solution every hour. Methylene blue concentration is measured using ultraviolet spectrophotometry. The test solution is sampled using a Shimadzu UV-1900i spectrometer, acquiring the ultraviolet-visible spectrum within a scanning width of 400-800 nm to obtain the pollutant concentration change C. t / C0.

[0038] The formula is as follows: C0: Initial concentration, C t Real-time concentration, A t absorbance, b: wavelength Molar absorptivity; The approximate rate equation for the first-order reaction kinetics at the liquid-solid interface, Langmuir-Hinshelwood (LH), is as follows: Where t is the illumination time, and K is the apparent constant. app K is a fundamental kinetic parameter for different photocatalysts. The LH model was used to calculate the K value of methylene blue degradation rate under different conditions. app and regression coefficient R 2 R 2 A value greater than 0.9 indicates that the LH equation is applicable to the photocatalytic degradation of methylene blue, ln(C t The curve / C0) shows a good linear relationship with the t curve.

[0039] Results Analysis: The photocatalytic degradation effects of the three catalysts were compared only after the reaction flask was placed in a dark box and allowed to stand for 12 hours for adsorption. This ruled out the accelerated photocatalytic degradation effect caused by the adsorption of methylene blue by the polyacrylamide aerogel in the catalyst prepared in Example 1. The results showed that the photocatalytic degradation effects of the high-entropy catalyst HEO with methylene blue as the degradation substrate, the acrylamide aerogel composite catalyst PAM@HEO supported on high-entropy spinel ferrite, and the traditional ferrite catalyst NFO (NiFe2O4) were compared.

[0040] This experiment used methylene blue (MB) as the degradation substrate to investigate the photocatalytic performance of the catalyst. The experimental results are as follows: Figure 3As shown in ab, in each experimental group, PAM@HEO exhibited the superior photocatalytic degradation performance. Within 45 minutes, the residual value C of methylene blue degraded by PAM@HEO was [value missing]. t The CO value decreased to 7.33%, and the degradation efficiency was 92.67%. To achieve similar results, HEO catalyst required 6-7 hours, while NFO (NiFe2O4) required up to 15 hours. The residual CO value of methylene blue after 7 hours of HEO degradation was... t The CO value decreased to 4.43%, and the degradation efficiency was 95.57%. Compared with the traditional nickel ferrite catalyst NFO, the high-entropy spinel ferrite catalyst showed stronger ability to degrade methylene blue. The PAM@HEO composite catalyst showed even stronger ability to degrade methylene blue than HEO, indicating that the aerogel-supported composite catalyst significantly improved the photocatalytic degradation performance.

[0041] Results Analysis: Effect of Aerogel Support on the Photocatalytic Degradation Performance of Catalysts Kinetic analysis of photocatalytic degradation of methylene blue, as follows Figure 3 As shown in c, the specific data is shown in Table 1. The performance rate constant K of PAM@HEO is... app The coefficient of performance (COP) reached 1.21621, significantly better than HEO (0.15455) and NFO (0.06571), representing 7.9 times and 18.5 times higher, respectively. These results indicate that polyacrylamide-based aerogels are effective supports for enhancing the catalytic performance of HEO, and the degradation performance of the catalyst is significantly improved after aerogel loading.

[0042] like Figure 3 As shown in d, the cyclic performance of the catalyst was verified by recovering and repeating the photocatalytic degradation of methylene blue. After five cycles, the degradation efficiency decreased from 93.71% to 87.76%, corresponding to an activity retention rate as high as 93.65%, indicating that the high-entropy spinel ferrite catalyst supported on polyacrylamide aerogel has excellent cyclic performance.

[0043] Table 1. Kinetic data of photocatalytic degradation of methylene blue by the catalyst Comparative Example 1 According to (Co) 0.4 Ni 0.2 Zn 0.2 Cu 0.2The stoichiometric ratio of Fe₂O₄ was used to prepare the mixture (i.e., 0.4:0.2:0.2:0.2:2, x = 0.4). Cobalt nitrate, nickel nitrate, zinc acetate, copper nitrate, and ferric nitrate were weighed out, and the resulting mixture was mixed with distilled water. The solution was adjusted to pH=7 with potassium hydroxide and transferred to a PTFE hydrothermal reactor. The reactor was incubated at 220℃ for 24 hours. After the reaction, the product in the reactor was centrifuged and washed to obtain precursor powder. The precursor was calcined at 800℃ for 2 hours and ground to obtain a tetroxide (Co). 0.4 Ni 0.2 Zn 0.2 Cu 0.2 The performance of Fe2O4 powder in degrading methylene blue was tested, and the results are as follows: Figure 4 As shown. The reaction process is as follows: 100 mL of methylene blue solution (concentration 10 mg / L) was measured, and the tetroxide (Co) was added. 0.4 Ni 0.2 Zn 0.2 Cu 0.2 50 mg of Fe2O4 powder. The removal rate (Rev(%)) of the simulated target pollutant methylene blue can be calculated using the following formula: Where C t C0 represents the concentration of organic pollutants in the filtrate at a certain moment; A represents the initial concentration of organic pollutants. t A0 represents the absorbance at the wavelength of maximum absorption of organic pollutants in the filtrate at a certain moment; A0 represents the absorbance at the initial wavelength of maximum absorption of organic pollutants. From Figure 4 It can be seen from the four groups of elements (Co) 0.4 Ni 0.2 Zn 0.2 Cu 0.2 Fe2O4 powder showed almost no catalytic degradation effect on methylene blue without light and persulfate (PDS), but under light, it showed some photocatalytic degradation effect on methylene blue, but the effect was poor and still lower than the photocatalytic degradation effect of PAM@HEO on methylene blue in Example 2.

[0044] Comparative Example 2 To further verify the photocatalytic performance of polyacrylamide aerogel-supported high-entropy spinel ferrite catalyst (PAM@HEO) and to eliminate the interference of selective adsorption of specific pollutants by the PAM support material on the degradation results, this embodiment selected a variety of typical organic pollutants as degradation substrates, including anionic dyes (methyl orange, Congo red), aromatic cyclic antibiotics (such as the fluoroquinolone antibiotic ciprofloxacin), and anionic antibiotics (sulfonamide antibiotic sodium sulfadiazine).

[0045] 100 mL each of methyl orange, Congo red, ciprofloxacin, and sulfadiazine sodium solutions with a concentration of 10 mg / L were prepared. 50 mg of the PAM@HEO catalyst prepared in Example 1 was added to each solution, and the mixtures were placed in a dark chamber and magnetically stirred for 12 hours. Samples were taken every hour to determine the concentration. The absorbance at the characteristic wavelengths of each pollutant was measured using UV-Vis spectrophotometry, and the adsorption rate was calculated.

[0046] The adsorption rate (Adsorb(%)) of the simulated target pollutant methylene blue can be calculated using the following formula: Where C t C0 represents the concentration of organic pollutants in the filtrate at a certain moment; A represents the initial concentration of organic pollutants. t A represents the absorbance at the wavelength of maximum absorption of organic pollutants in the filtrate at a certain moment; A0 represents the absorbance at the wavelength of maximum absorption of the initial organic pollutants.

[0047] like Figure 5 The experimental results showed that the adsorption rate of PAM@HEO for the above substrates was less than 5%, indicating that polyacrylamide aerogel had no significant adsorption effect on anionic dyes and selected antibiotic pollutants. The concentration reduction observed in the photocatalytic degradation experiment of methylene blue can be attributed to the photocatalytic reaction rather than physical adsorption.

[0048] Using 50 mg of PAM@HEO, HEO, and NFO prepared in Example 1 as catalysts, after 12 h of adsorption equilibrium, the reaction system was subjected to photocatalytic degradation experiments under visible light. The degradation efficiencies for different pollutants were compared under the same conditions. The removal rate (Rev(%)) of the simulated target pollutant methylene blue can be calculated using the following formula: Where C t C0 represents the concentration of organic pollutants in the filtrate at a certain moment; A represents the initial concentration of organic pollutants. t A represents the absorbance at the wavelength of maximum absorption of organic pollutants in the filtrate at a certain moment; A0 represents the absorbance at the wavelength of maximum absorption of the initial organic pollutants.

[0049] like Figure 6 Experimental results showed that, taking methyl orange as an example, PAM@HEO achieved a degradation rate of 56.49% within 6 hours, while HEO only achieved 24.10%. For Congo red, PAM@HEO achieved a degradation rate of 36.25% within 6 hours, significantly better than HEO. In the antibiotic contaminant system, PAM@HEO achieved degradation rates of 65.58% and 64.02% for ciprofloxacin and sulfadiazine sodium, respectively, while HEO's degradation rates were both below 40%.

[0050] The above results demonstrate that the PAM@HEO composite catalyst exhibits broad-spectrum and highly efficient photocatalytic degradation capabilities for various recalcitrant organic pollutants under visible light. Its superior performance stems from the synergistic effect of the high-entropy ferrite and aerogel support, rather than physical adsorption. The PAM molecular chain contains polar functional groups such as C=O and -NH2, and the non-bonded electrons on its heteroatoms can undergo n-π transitions, giving PAM a certain degree of light absorption and electronic excitation capabilities. When the catalyst absorbs light energy and generates electron-hole pairs, some of the energy can be transferred to the PAM molecules, causing their electrons to transition to an excited state, thus forming an effective interfacial electron transfer channel between the catalyst and PAM. Furthermore, the polar polymer structure of PAM facilitates the construction of a stable interface and enhances electron transport capabilities, thereby promoting the migration and separation of photogenerated electrons, inhibiting electron-hole pair recombination, and ultimately improving the photocatalytic degradation efficiency.

Claims

1. A method for preparing polyacrylamide aerogel supported on a high-entropy spinel ferrite catalyst, characterized in that, Includes the following steps: Prepare an aqueous solution of acrylamide using boiled deionized water, and purge with nitrogen to remove residual dissolved oxygen; The solution was stirred at a constant temperature of 20-60℃, and potassium persulfate (K2S2O8) and accelerator tetramethylethylenediamine were added to carry out an acrylamide condensation reaction until the solution became a viscous polyacrylamide hydrogel. High-entropy spinel ferrite catalyst powder was added to the hydrogel, and the mixture was kept warm and stirred before being freeze-dried to obtain a polyacrylamide hydrogel loaded with high-entropy spinel ferrite catalyst. The high-entropy spinel ferrite catalyst has a general formula of Cu 1 / 2 Zn 1 / 2 Fe 2 / 3 Co 2 / 3 Ni 2 / 3 O4, and the catalyst has a particle size of 50-200 nm.

2. The preparation method according to claim 1, characterized in that, The high-entropy spinel ferrite catalyst is prepared using the following steps: Weigh ferric nitrate, nickel nitrate, cobalt nitrate, zinc acetate, and copper nitrate in a molar ratio of 1:1:1:0.76:0.76, dissolve and mix them in deionized water to obtain a metal ion salt solution. Prepare a potassium hydroxide solution by slowly adding it dropwise to a metal ion salt solution and stirring until a solution with pH=7 is obtained. The solution was transferred to a hydrothermal reactor for hydrothermal reaction. After natural cooling, the mixture was filtered, and the filter residue was dried to obtain precursor powder. The precursor powder was ground and then calcined in a high-temperature furnace at 700~900℃ to obtain a high-entropy spinel ferrite catalyst.

3. The preparation method according to claim 2, characterized in that, The hydrothermal reaction temperature was 220℃ and the time was 24h.

4. The preparation method according to claim 2, characterized in that, The precursor powder was ground and then calcined in a high-temperature furnace at 800°C to obtain a high-entropy spinel ferrite catalyst.

5. The preparation method according to claim 2, characterized in that, The calcination process involves a heating rate of 5℃ / min, a cooling rate of 5℃ / min, and a holding time of 2 hours at a concentration of 1 mol / L.

6. The preparation method according to claim 2, characterized in that, The added potassium persulfate (K2S2O8) is freshly prepared potassium persulfate, and the amount added is 1-1.5% wt of polyacrylamide.

7. The preparation method according to claim 2, characterized in that, The added accelerator, tetramethylethylenediamine, has a molar ratio of 1:1 to potassium persulfate.

8. The preparation method according to claim 1, characterized in that, The acrylamide condensation reaction process requires constant temperature stirring at 50°C for more than 30 minutes, and the stirring speed should be increased and the reaction vessel sealed.

9. The preparation method according to claim 1, characterized in that, The hydrogel was freeze-dried in a vertical freeze dryer under conditions of -60°C and vacuum for 24 hours.

10. The application of the polyacrylamide hydrogel supported on a high-entropy spinel ferrite catalyst as described in any one of claims 1-9 in the degradation of dyes and antibiotics under light irradiation without the addition of oxidants.

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