Iron-zinc spinel / diatomite catalytic material as well as preparation method and application thereof
By preparing iron-zinc spinel/diatomite nanocomposites, the problems of insufficient catalyst stability and activity in existing photocatalytic technologies have been solved, achieving efficient degradation of organic pollutants in water, especially atrazine, with good reusability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-03
- Publication Date
- 2026-03-13
AI Technical Summary
Existing photocatalytic technologies for treating highly stable organic pollutants suffer from problems such as high recombination rate of photogenerated carriers, small specific surface area, insufficient exposure of active sites, easy aggregation and deactivation, and difficulty in recovery. Furthermore, impurities in actual water bodies affect the degradation efficiency.
Using iron-zinc spinel/diatomite catalytic materials, a nanocomposite material was prepared by hydrothermal method to improve the specific surface area and porosity of the catalyst, enhance light absorption capacity, inhibit photogenerated carrier recombination, and generate a large number of active species through photo-synergistic activation of persulfate, thereby achieving the magnetic properties and easy recyclability of the catalyst.
It improves the stability and activity of the catalyst, enhances the degradation effect on organic pollutants, especially the removal rate of pollutants such as atrazine, and has good reusability.
Smart Images
Figure CN121648924A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical materials technology, and particularly relates to an iron-zinc spinel / diatomite catalytic material, its preparation method and application. Background Technology
[0002] Atrazine (ATZ, also known as atrazine), chemical formula C8H 14 ClN5 is primarily used to control weed growth in various agricultural crops (such as corn, sorghum, and sugarcane). To date, ATZ residues have been detected in surface water, groundwater, and lakes in numerous countries worldwide. It has been reported that ATZ can interfere with neurotransmitter transmission and cause neurotoxicity when it enters the body. Long-term exposure to ATZ can damage the human endocrine system, leading to infertility. In addition, ATZ can trigger a range of diseases and even cancer; long-term exposure can also lead to breast and ovarian cancer in animals. Furthermore, atrazine and its related metabolites in the aquatic environment have toxic effects on organisms at different levels of the ecosystem, altering the composition and population size of species and communities. Therefore, how to efficiently remove atrazine from the aquatic environment is a pressing environmental problem that needs to be addressed.
[0003] Existing water treatment technologies include flotation, coagulation / flocculation, adsorption, ion exchange, biodegradation, and phytoremediation. However, these technologies generally have limitations: adsorption only achieves the transfer of pollutants rather than complete degradation, and the materials after adsorption saturation require further treatment, which can easily cause secondary pollution; biodegradation has low efficiency and long cycle for the degradation of highly stable atrazine, and is significantly affected by environmental factors such as temperature and pH; traditional chemical oxidation methods (such as ozone oxidation and chlorination) are energy-intensive and easily produce toxic and harmful substances such as chlorinated byproducts.
[0004] Photocatalysis technology has broad application prospects in water treatment due to its advantages such as simple process, low energy consumption, green and environmentally friendly nature, and thorough degradation of substances. However, when treating pollutants with complex structures, high stability, and difficulty in degradation, the degradation capacity of photocatalysis itself is often insufficient. In this case, combining it with other powerful degradation methods becomes crucial. In recent years, scientists have studied the combination of photocatalysis and PMS activation as a promising method for removing organic pollutants. In this method, externally added chemical reagents are excited by the catalyst to generate hydroxyl radicals (·OH) or sulfate radicals with high oxidation potentials. ) and singlet oxygen ( 1 Non-radical pathways such as O2 have the characteristics of being more likely to catalyze the degradation of electron-rich organic pollutants and resisting environmental interference, and can effectively degrade pollutants.
[0005] However, existing synergistic systems generally suffer from the following problems with catalysts: First, the high recombination rate of photogenerated carriers leads to insufficient generation of active species; second, the catalyst has a small specific surface area, resulting in insufficient exposure of active sites and low PMS activation efficiency; third, the catalyst is prone to aggregation and deactivation, and is difficult to separate and recover from the water body after the reaction, limiting its engineering applications. Furthermore, impurities such as humic acid and ions present in actual water bodies easily undergo quenching reactions with active species, further reducing degradation efficiency.
[0006] Therefore, developing a highly active, stable, and easily recyclable catalyst and optimizing the photocatalyst-activated persulfate degradation system are of great significance for improving the removal efficiency of atrazine in water. Summary of the Invention
[0007] The main objective of this invention is to provide an iron-zinc spinel / diatomite catalytic material, its preparation method, and its application, in order to overcome the shortcomings of the prior art.
[0008] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: According to a first aspect of the present invention, a method for preparing an iron-zinc spinel / diatomite catalytic material is provided, comprising the following steps: S1. Add diatomaceous earth to nitric acid solution, mix well, then add Zn(NO3)2·6H2O and Fe(NO3)3·9H2O, mix well, add NaOH solution dropwise, and stir continuously to obtain precursor solution; S2. The precursor solution described in step S1 is transferred into a polytetrafluoroethylene reactor, and the polytetrafluoroethylene reactor is placed in a homogeneous reactor for hydrothermal reaction. After the hydrothermal reaction described in step S3 and S2 is completed, the polytetrafluoroethylene reactor is cooled to room temperature, the reaction product is collected, and the reaction product is centrifuged, washed, dried, and ground to obtain the iron-zinc spinel / diatomite catalytic material.
[0009] Furthermore, in step S1, the addition ratio of Zn(NO3)2·6H2O and Fe(NO3)3·9H2O is 1:1-4; the amount of diatomaceous earth added accounts for 5-30 wt% of the total mass of iron-zinc spinel expected to be generated from Zn(NO3)2·6H2O and Fe(NO3)3·9H2O.
[0010] Furthermore, in step S1, the concentration of the nitric acid solution is 2 mol / L, and the concentration of the NaOH solution is 2 mol / L; the diatomaceous earth is added to the nitric acid solution and mixed uniformly by ultrasonication, and the continuous stirring is done by magnetic stirring; the ultrasonic treatment and magnetic stirring time are both 30 minutes; the ultrasonic treatment power is 200-500W.
[0011] Furthermore, in step S2, the temperature of the hydrothermal reaction is 140-200 ℃, and the time of the hydrothermal reaction is 4-12 hours.
[0012] Furthermore, after the hydrothermal reaction in step S2 is completed, the mixture is naturally cooled to room temperature at a rate not exceeding 20°C / hour.
[0013] Furthermore, in step S3, the conditions for centrifugal washing are: centrifugation speed of 5000 rpm, centrifugation time of 5 minutes / cycle, and alternating washing with deionized water and ethanol 3 to 5 times; the drying is vacuum drying, drying temperature of 80-90℃, and drying time of 3-4 hours.
[0014] Furthermore, in step S3, the material is sieved after grinding, with a sieve mesh size of 100 mesh.
[0015] According to a second aspect of the present invention, an iron-zinc spinel / diatomite nanocomposite material prepared by any of the above-described preparation methods is provided, wherein the iron-zinc spinel is uniformly loaded in the form of nanoparticles on the surface and within the pores of the diatomite.
[0016] According to a third aspect of the present invention, an application of the above-described iron-zinc spinel / diatomite nanocomposite material as a catalyst in the photo-synergistic activation of persulfate oxidation degradation of organic pollutants is provided.
[0017] Furthermore, the organic pollutant includes ATZ; the reaction conditions for the photosynergistic activation of persulfate are: initial pH of wastewater of 3-11, catalyst dosage of 0.5-1.25 g / L, and potassium persulfate dosage of 0.3-0.5 g / L; the organic pollutant also includes one or more of diuron (DUR), bisphenol A (BPA), norfloxacin (NOR), and methylene blue (MB).
[0018] Compared with the prior art, the advantages of the present invention include: This invention provides an iron-zinc spinel / diatomite catalytic material, its preparation method, and its application. 1) This invention prepares an iron-zinc spinel / diatomite nanocatalyst with strong stability and strong catalytic activity. The preparation method of this invention is a hydrothermal method, which is mild and simple to operate, suitable for industrial production and application, and the preparation time is shortened to 6 hours, which greatly improves efficiency.
[0019] 2) This invention introduces diatomaceous earth into ZnFe2O4, which increases the specific surface area and porosity of the catalyst, effectively suppresses the agglomeration effect of the material, and achieves uniform dispersion of iron-zinc spinel nanoparticles. In addition, the introduction of diatomaceous earth enhances the light absorption capacity, improves the separation ability of photogenerated carriers and holes, and effectively suppresses the recombination of photogenerated carriers, thereby increasing the amount of active species generated.
[0020] 3) The sample prepared in this invention is a catalytic material. Through electron-hole pairs generated by light irradiation and electron transfer from the iron-zinc bimetallic material surface, persulfate is effectively activated to produce more active species. Specifically, the catalyst generates a large amount of active species in the photoactivated persulfate system. 1 O2 and the new Free radicals improve the removal efficiency of pollutants in water bodies.
[0021] 4) The sample prepared by this invention is a magnetic material, which improves the recycling of the catalyst. Attached Figure Description
[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 X-ray diffraction (XRD) patterns of different materials and iron-zinc spinel / diatomite after use; Figure 2 FTIR spectra of different materials; Figure 3 XPS spectra of iron-zinc spinel diatomite before and after use; Figure 4 The graph shows the photo-synergistic activation effect of persulfate on atrazine by the iron-zinc spinel / diatomite catalyst material with different hydrothermal synthesis times according to the present invention. Figure 5 The graph shows the photo-synergistic activation effect of persulfate on atrazine by the iron-zinc spinel / diatomite catalyst at different hydrothermal synthesis temperatures of this invention. Figure 6 The graph shows the photo-synergistic activation effect of persulfate on atrazine by iron-zinc spinel / diatomite catalytic materials with different diatomite contents according to the present invention. Figure 7 The graph shows the degradation effect of photosynergistic activation of persulfate on atrazine by different dosages of iron-zinc spinel / diatomite catalysts according to the present invention. Figure 8 The graph shows the photo-synergistic activation effect of the iron-zinc spinel / diatomite catalytic material with diatomite content of the present invention on the degradation effect of different concentrations of persulfate on atrazine. Figure 9 This is a comparison of the degradation effects of iron-zinc spinel / diatomite and iron-zinc spinel catalyst materials of the present invention on atrazine in different systems of photocatalysis, persulfate, and photo-co-activated persulfate. Figure 10 This is a comparison of the photo-synergistic activation effect of persulfate on atrazine degradation by the iron-zinc spinel / diatomite and iron-zinc spinel catalyst materials of the present invention under different initial pH conditions; Figure 11 This is a comparison of the degradation effects of the iron-zinc spinel / diatomite catalytic material of the present invention on atrazine after 5 cycles of photosynergistic activation of persulfate; Figure 12 This is a comparison of the degradation effects of the iron-zinc spinel / diatomite catalytic material of the present invention on various dyes such as atrazine (ATZ), diuron (DUR), bisphenol A (BPA), norfloxacin (NOR) and methylene blue (MB) in different photo-synergistic activated persulfate systems for 20 minutes. Figure 13 Results of quenching experiments for different systems; Figure 14 For different systems 1 EPR spectrum of O2; Figure 15 EPR spectra of different h⁺ systems; Figure 16 For different systems EPR map; Figure 17 For different systems EPR map; Figure 18 For different systems, i−t curves are given. Detailed Implementation
[0023] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.
[0024] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.
[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.
[0026] This invention provides a method for preparing an iron-zinc spinel / diatomite catalytic material, comprising the following steps: S1. Diatomaceous earth is added to a nitric acid solution and mixed thoroughly. Then, Zn(NO3)2·6H2O and Fe(NO3)3·9H2O are added and mixed thoroughly. NaOH solution is added dropwise while continuously stirring to obtain a precursor solution. The ratio of Zn(NO3)2·6H2O to Fe(NO3)3·9H2O is 1:1-4. The amount of diatomaceous earth added accounts for 5-30 wt% of the total mass of iron-zinc spinel expected to be generated from Zn(NO3)2·6H2O and Fe(NO3)3·9H2O. The concentration of the nitric acid solution is 2 mol / L, and the concentration of the NaOH solution is 2 mol / L. The diatomaceous earth is added to the nitric acid solution and mixed thoroughly by ultrasonication. The continuous stirring is done by magnetic stirring. The ultrasonic treatment and magnetic stirring time are both 30 minutes. The ultrasonic treatment power is 200-500W.
[0027] S2. Transfer the precursor solution described in step S1 into a polytetrafluoroethylene (PTFE) reactor, and place the PTFE reactor in a homogeneous reactor for hydrothermal reaction; the temperature of the hydrothermal reaction is 140-200 °C, and the reaction time is 4-12 hours. After the hydrothermal reaction is completed, allow it to cool naturally to room temperature at a rate not exceeding 20 °C / hour.
[0028] After the hydrothermal reaction described in step S2 is completed, the polytetrafluoroethylene reactor is cooled to room temperature, the reaction product is collected, and the product is centrifuged, washed, dried, and ground to obtain the iron-zinc spinel / diatomite catalyst. The centrifugation conditions are: centrifugation speed 5000 rpm, centrifugation time 5 minutes / cycle, and alternating washing with deionized water and ethanol 3 to 5 times; the drying is vacuum drying at a temperature of 80-90℃ for 3-4 hours. After grinding, the material is sieved through a 100-mesh sieve.
[0029] According to a second aspect of the present invention, an iron-zinc spinel / diatomite nanocomposite material prepared by any of the above-described preparation methods is provided, wherein the iron-zinc spinel is uniformly loaded in the form of nanoparticles on the surface and within the pores of the diatomite.
[0030] According to a third aspect of the present invention, an application is provided of the above-mentioned iron-zinc spinel / diatomite nanocomposite material as a catalyst in the photo-co-activated persulfate oxidation degradation of organic pollutants. The organic pollutants include ATZ; the photo-co-activated persulfate reaction conditions are: initial pH of wastewater 3-11, catalyst dosage 0.5-1.25 g / L, and potassium persulfate dosage 0.3-0.5 g / L; the organic pollutants also include one or more of diuron (DUR), bisphenol A (BPA), norfloxacin (NOR), and methylene blue (MB).
[0031] This invention has revealed that the catalyst prepared using the method of this invention can synergistically activate persulfate under light conditions to generate a large number of photogenerated electron-hole pairs and free radicals (·SO4). − O2 − and ·OH) and non-free radicals ( 1 It utilizes O2 and electron transfer to efficiently degrade ATZ and has good reusability.
[0032] To better understand the technical solution of the present invention, the following detailed discussion is provided in conjunction with specific embodiments.
[0033] Example 1: Hydrothermal Synthesis and Preparation of Iron-Zinc Spinel / Diatomite Catalyst
[0034] Mix 0.048 g (10 wt%) of diatomaceous earth with 20 mL of 2 mol·L⁻¹ 1 Pour the nitric acid solution into a beaker and sonicate for 20 minutes. Add 4 mmol of ferric nitrate nonahydrate (1.616 g) and 2 mmol of zinc nitrate hexahydrate (0.482 g), and stir continuously for 30 minutes. Then, add 40 mL of 2 mol·L⁻¹ solution. 1 Sodium hydroxide solution was added dropwise to the mixture to form a reddish-brown suspension. The suspension was stirred for another 30 minutes and then transferred to a 100 mL hydrothermal autoclave. The reaction conditions were set to 160°C and continued for 6 hours. After cooling to room temperature, the obtained catalyst was washed three times with deionized water and anhydrous ethanol by centrifugation. The washing protocol was as follows: once with distilled water, three times with ethanol, and twice with distilled water, each time centrifuged at 5000 rpm for 5 minutes. Finally, the catalyst was filtered through a 0.22 μm microporous membrane, transferred to a glass dish with tweezers, and vacuum dried in a vacuum oven at 90 °C for 4 hours. After grinding, it was passed through a 100-mesh sieve and designated as 10-ZFD.
[0035] Comparative Example 1: Hydrothermal Synthesis and Preparation of Iron-Zinc Spinel Catalyst
[0036] The difference from Example 1 is that it does not contain diatomaceous earth. A ZnFe2O4 catalyst was prepared, denoted as ZF.
[0037] Experimental Example 1: Structural Analysis of Photoresponsive Catalytic Materials for Activating Persulfate under the Same Hydrothermal Synthesis Conditions
[0038] pass Figure 1 X-ray diffraction (XRD) patterns were used to investigate the phase purity and crystal properties of pure diatomaceous earth, ZF, and 10-ZFD. The characteristic peaks of the prepared catalysts showed good agreement with the standard ZnFe2O4 pattern (PDF#22–1012). The characteristic peaks at 2θ = 30°, 35.3°, 42.8°, 56.6°, and 62.2° corresponded to the (220), (311), (400), (511), and (440) crystal planes of ZnFe2O4, respectively. Compared with the XRD pattern of ZF, the diffraction peaks in 10-ZFD were slightly broadened and the intensity decreased, indicating that the loading of DT and ZF reduced the diffraction intensity of the crystal particles.
[0039] according to Figure 2 FTIR spectra of diatomaceous earth, ZF, and 10-ZFD. Diatomaceous earth at 1091 cm⁻¹. −1 803 cm −1 and 465 cm −1 The peak value at 555 cm⁻¹ is caused by the asymmetric tensile vibration, symmetric tensile vibration, and bending vibration of the Si-O-Si bond. −1 The spectral band at 1629 cm⁻¹ corresponds to the stretching vibration of Zn / Fe-O. −1 The band at 3412 cm⁻¹ can be attributed to surface hydroxyl groups and adsorbed water molecules. −1 The broad and strong spectral band at 895 cm⁻¹ corresponds to the stretching vibration of OH groups on the surface of the prepared sample. The 10-ZFD composite material exhibits this vibration at 895 cm⁻¹. −1 The new characteristic peak at this location is attributed to the stretching vibration of the Si−O−Fe / Zn bond, and its formation originates from the interaction between the silanol groups on the diatomaceous earth surface and the metal ions (Fe) in ZnFe2O4. 3+ / Zn 2+ The condensation reaction of zinc spinel / diatomite was observed. FTIR spectroscopy results indicate that the iron-zinc spinel / diatomite catalyst was successfully synthesized via a hydrothermal method.
[0040] To investigate the constituent elements and valence states of the prepared iron-zinc spinel / diatomite, XPS spectroscopy was used to analyze the materials before and after use. Figure 3 The full-spectrum test results of iron-zinc spinel / diatomite are presented. In the full spectrum of sample 10-ZFD, Zn, Fe, O, and Si elements are clearly present, indicating the successful preparation of the iron-zinc spinel / diatomite catalytic material. Furthermore, the presence of elemental peaks in the iron-zinc spinel / diatomite before and after use demonstrates the material's stability.
[0041] Experimental Example 2: ATZ Degradation Performance of Iron-Zinc Spinel / Diatomite Catalysts under Different Hydrothermal Synthesis Conditions
[0042] Compared with Example 1, the preparation method of the photo-co-activated PMS catalyst for atrazine degradation in this example differs in that the synthesis time is selected as 4, 6, 8, 10, and 12 h; the synthesis temperature is selected as 140, 160, 180, and 200 ℃; and the amount of diatomaceous earth added is selected as 5, 10, 15, 20, and 30 wt%, respectively denoted as 5, 10, 15, 20, and 30-ZFD. The results are as follows: Figure 4 , Figure 5 , Figure 6 As shown, it is demonstrated that under the conditions of Example 1, the 10 wt% iron-zinc spinel / diatomite (10-ZFD) synthesized at a catalyst dosage of 1 g / L, a PMS concentration of 0.5 g / L, and a photo-activated PMS system exhibits superior ATZ degradation performance.
[0043] Experimental Example 3: Study on the degradation of ATZ in water by photosynergistic activation of PMS by iron-zinc spinel / diatomite Example 1: The catalyst synergistically photoactivated persulfate at concentrations of 0.5, 0.75, 0.1, and 1.25 g / L for the removal of ATZ from water. The results are as follows: Figure 7 As shown, at a catalyst dosage of 1 g / L, 10-ZFD exhibited superior ATZ catalytic degradation performance. In Example 1, the catalyst was used at a concentration of 0.1 g / L to synergistically photoactivate 0.3, 0.4, 0.5, and 0.6 g / L persulfate for ATZ removal from water. The results are as follows... Figure 8 As shown, at a persulfate dosage of 0.5 g / L, 10-ZFD exhibits superior ATZ catalytic degradation performance.
[0044] Experiment Example 4: Performance Comparison of ATZ Removal from Water in Different Iron-Zinc Spinel / Diatomite Systems
[0045] Add 100 mL of 5 mg / LATZ solution to the photocatalytic reaction vessel, then add 0.1 g of catalyst. Place the photocatalytic reaction vessel in a photochemical reaction chamber and connect it to a constant temperature water bath. Take a sample at time 0, turn on the photocatalytic reactor lamp, and add 0.05 g of weighed PMS particles. During the reaction, take 3 mL samples at regular intervals, filter through a 0.45 µm filter, and add 200 µL of 0.5 mol / L Na₂S₂O₃•5H₂O to terminate the reaction. Transfer the samples to a liquid chromatography vial for liquid chromatography analysis.
[0046] Research results are as follows Figure 9The degradation effects of 10-ZFD (Example 1) and ZF (Comparative Example 1) on ATZ in photocatalysis, persulfate activation, and photo-synergistic activation persulfate systems were investigated. The removal rates of ATZ by photocatalysis alone were all less than 5%, indicating that under visible light conditions, the photogenerated electron-hole pairs and corresponding free radicals generated by ZF and 10-ZFD cannot effectively oxidize ATZ. In the persulfate systems alone, the removal rates of ATZ by ZF+PMS and 10-ZFD+PMS reached 28.66% and 38.23%, respectively, due to the redox synergistic effect of the bimetallic compounds and the presence of multivalent transition metals in the catalysts. In the photo-synergistic persulfate systems, the removal rates of ZF+Vis+PMS and 10-ZFD+Vis+PSM were 76.4% and 100%, respectively, significantly improving the ATZ removal rate. 10-ZFD exhibited the best catalytic synergistic effect in the degradation of ATZ.
[0047] Experimental Example 5: Study on the stability and adaptability of PMS activated by photosynthetic iron-zinc spinel / diatomite The activity of the 10-ZFD catalyst prepared in Example 1 was tested in ATZ solutions with different initial pH conditions, and the results are as follows: Figure 10 As shown, the 10-ZFD catalyst prepared in Example 1 exhibits excellent photosynergistic persulfate catalytic activity over a wide range of acid and alkaline conditions. Figure 11 The 10-ZFD catalyst maintained excellent degradation performance (≥98%) against ATZ under five cycles. Furthermore, the 10-ZFD catalyst prepared in Example 1 was used in conjunction with photoactivated persulfate to investigate the removal of different pollutants, including atrazine (ATZ), diuron (DUR), bisphenol A (BPA), norfloxacin (NOR), and methylene blue (MB). The results are as follows... Figure 12 As shown, the 10-ZFD+Vis+PMS system exhibits excellent catalytic degradation performance for a variety of pollutants and has broad adaptability (≥97%).
[0048] Experimental Example 6: Study on the Mechanism of Photosynergistic Activation of PMS by Iron-Zinc Spinel / Diatomite To elucidate the synergistic effect of 10-ZFD and PMS on ATZ degradation under visible light irradiation, the quenching experimental results of the 10-ZFD+Vis+PMS and 10-ZFD+PMS systems were compared. Figure 13 The results showed that the contribution trend of ROS to ATZ removal was consistent in both systems. 1 O2 > •OH, •SO4 − O2 − However, the degradation and quenching effects are more significant in the 10-ZFD+Vis+PMS system because it generates more active species. Meanwhile, Figure 14 -17 electron spin resonance (EPR) analysis indicates that the introduction of photocatalysis significantly enhances the PMS's ability to generate reactive oxygen species (ROS) compared to the 10-ZFD+PMS system. Furthermore, DMPO−•O2 was observed after the introduction of light. − The signal intensity increased significantly over time, indicating the presence of •O2 in the 10-ZFD+Vis+PMS system. − In contrast, this signal was not detected in the system using only 10-ZFD+PMS. This is attributed to the conduction band (CB) position (−0.93 eV) of the 10-ZFD catalyst being higher than that of the PMS catalyst. The redox potential (−0.33 eV) allows photogenerated electrons to be generated. .
[0049] By analyzing the chronoampere (i−t) curves of the 10-ZFD+PMS and 10-ZFD+PMS+Vis systems respectively, the electron transfer process between ATZ, the catalyst, and PMS was further elucidated. Figure 18 As shown, the enhanced current output after adding ATZ and PMS indicates an electron transfer process between ATZ, the catalyst, and PMS. Most importantly, the 10-ZFD+PMS+Vis system exhibits a significant advantage, with a much higher photocurrent density compared to the 10-ZFD+PMS system. This phenomenon further demonstrates the excellent electron transfer efficiency of the 10-ZFD+PMS+Vis system. These experimental results prove that iron-zinc spinel diatomaceous earth possesses excellent activation ability for PMS under photoresponsive conditions.
[0050] The above descriptions are merely some embodiments of the present invention. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.
Claims
1. A method for preparing an iron-zinc spinel / diatomite catalytic material, characterized in that, Includes the following steps: S1. Add diatomaceous earth to nitric acid solution, mix well, then add Zn(NO3)2·6H2O and Fe(NO3)3·9H2O, mix well, add NaOH solution dropwise, and stir continuously to obtain precursor solution; S2. The precursor solution described in step S1 is transferred into a polytetrafluoroethylene reactor, and the polytetrafluoroethylene reactor is placed in a homogeneous reactor for hydrothermal reaction. After the hydrothermal reaction described in step S3 and S2 is completed, the polytetrafluoroethylene reactor is cooled to room temperature, the reaction product is collected, and the reaction product is centrifuged, washed, dried, and ground to obtain the iron-zinc spinel / diatomite catalytic material.
2. The preparation method of the iron-zinc spinel / diatomite catalytic material according to claim 1, characterized in that, In step S1, the addition ratio of Zn(NO3)2·6H2O and Fe(NO3)3·9H2O is 1:1-4; the amount of diatomaceous earth added accounts for 5-30 wt% of the total mass of iron-zinc spinel expected to be generated from Zn(NO3)2·6H2O and Fe(NO3)3·9H2O.
3. The preparation method of the iron-zinc spinel / diatomite catalytic material according to claim 1, characterized in that, In step S1, the concentration of the nitric acid solution is 2 mol / L, and the concentration of the NaOH solution is 2 mol / L; the diatomaceous earth is added to the nitric acid solution and mixed uniformly by ultrasonication, and the continuous stirring is done by magnetic stirring; the ultrasonic treatment and magnetic stirring time are both 30 minutes; the ultrasonic treatment power is 200-500W.
4. The preparation method of the iron-zinc spinel / diatomite catalytic material according to claim 1, characterized in that, In step S2, the temperature of the hydrothermal reaction is 140-200 ℃, and the time of the hydrothermal reaction is 4-12 hours.
5. The preparation method of the iron-zinc spinel / diatomite catalytic material according to claim 1, characterized in that, After the hydrothermal reaction in step S2 is completed, the mixture is naturally cooled to room temperature at a rate not exceeding 20°C / hour.
6. The preparation method of the iron-zinc spinel / diatomite catalytic material according to claim 1, characterized in that, In step S3, the centrifugal washing conditions are as follows: centrifugation speed 5000 rpm, centrifugation time 5 minutes / cycle, and alternating washing with deionized water and ethanol 3 to 5 times; the drying is vacuum drying, drying temperature is 80-90℃, and drying time is 3-4 hours.
7. The preparation method of the iron-zinc spinel / diatomite catalytic material according to claim 1, characterized in that, In step S3, the material is ground and then sieved with a sieve mesh size of 100 mesh.
8. An iron-zinc spinel / diatomite nanocomposite material prepared by the preparation method according to any one of claims 1 to 7, characterized in that, In the composite material, iron-zinc spinel is uniformly loaded in the form of nanoparticles on the surface and within the pores of diatomaceous earth.
9. The application of the iron-zinc spinel / diatomite nanocomposite material as described in claim 8 as a catalyst in the photo-synergistic activation of persulfate oxidation and degradation of organic pollutants.
10. The application according to claim 9, characterized in that, The organic pollutants include ATZ; the reaction conditions for the photo-synergistic activation of persulfate are: initial pH of wastewater of 3-11, catalyst dosage of 0.5-1.25 g / L, and potassium persulfate dosage of 0.3-0.5 g / L; the organic pollutants also include one or more of diuron, bisphenol A, norfloxacin, and methylene blue.