Preparation method and application of persulfate catalytic material

Abstract

This invention discloses a method for preparing persulfate catalytic materials. Carbon nanotubes (CNTs) are doped into iron molybdate via hydrothermal synthesis to form a heterogeneous persulfate catalytic composite material. This invention successfully synthesizes the composite material CNTs@FeMoO4 by doping CNTs into FeMoO4 using a simple hydrothermal synthesis method. This composite material is then used as a catalyst for heterogeneous persulfate catalysis, achieving efficient degradation of pollutants. The prepared CNTs@FeMoO4 composite material exhibits certain stability and reusability. Furthermore, the CNTs@FeMoO4 / PS system has broad applicability and can effectively degrade various organic pollutants, demonstrating promising development prospects and suitability for widespread application.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for oxidative degradation of tetracycline in wastewater. Background Technology

[0002] Common organic pollutants in water bodies mostly originate from industrial wastewater from dyeing, pharmaceuticals, coking, and petrochemical industries. These pollutants are characterized by complex composition, poor biodegradability, stable molecular structure, and high toxicity. They can accumulate in organisms and the human body through the food chain, causing various diseases and posing a serious threat to human health. Therefore, the treatment of pollutants in water bodies has become an important and urgent problem to be solved.

[0003] Compared to the Fenton method, which uses H2O2 to generate hydroxyl radicals (OH), the SO2 generated by activating persulfate... 4- • It exhibits higher selectivity for pollutants, and persulfates are relatively stable, offering advantages such as ease of storage, transportation, and the ability to cover large remediation areas. Therefore, based on SO2... 4- Advanced oxidation technologies (AOPs) have received widespread attention in recent years. Persulfates (PSs) mainly include asymmetric permonosulfate (PMS) and symmetric perdisulfate (PDS). Persulfates are relatively stable at room temperature and can be activated to treat pollutants through heating, ultraviolet (UV), ultrasound (US), and transition metal (TM) methods. Activated PS can generate SO4-, breaking down complex and difficult-to-degrade organic matter into various intermediates, further transforming it into water, carbon dioxide, and other mineral salts. Activated PS systems can effectively mineralize organic pollutants. Although thermally activated PS can effectively remove pollutants, the entire process requires a large amount of energy, making it too costly. Radiation activation methods such as UV and US require large-scale equipment. Therefore, finding a material that can catalyze persulfates, making its system universally applicable and capable of degrading pollutants, is an urgent problem to be solved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a persulfate catalytic material with good stability and reusability, and which has a certain degree of universal applicability to systems composed of persulfates.

[0005] Another objective of this invention is to prepare persulfate catalytic materials using the above-described preparation method.

[0006] Another objective of this invention is to provide specific applications of the above-mentioned persulfate catalytic material.

[0007] To achieve the above objectives, the present invention provides a method for preparing a persulfate catalytic material, which involves doping carbon nanotubes into ferric molybdate via hydrothermal synthesis to form a heterogeneous catalytic persulfate composite material. The specific preparation process includes the following steps:

[0008] (1) Weigh out the carbon nanotubes for later use;

[0009] (2) Place the weighed carbon nanotubes into a dilute hydrochloric acid solution and sonicate for 15 minutes to obtain a suspension.

[0010] (3) Add NaMoO4·2H2O to the obtained suspension solution, stir to dissolve, and obtain a mixed solution;

[0011] (4) Add FeSO4·5H2O to the prepared mixed solution, control the temperature at 25℃, and continue stirring for 15 min to obtain the reaction solution;

[0012] (5) Pour the well-mixed reaction solution into the reaction vessel, then place the reaction vessel into a forced-air drying oven and keep it at 180°C for 4 hours;

[0013] (6) After the reactor cools down to room temperature, remove the reaction solution and clean it.

[0014] Wash three times with deionized water and anhydrous ethanol at a speed of 6000 r / min;

[0015] (7) Place the centrifuged product into a forced-air drying oven and dry it at 60°C for 16 hours;

[0016] (8) After the dried product is ground into powder, it is obtained.

[0017] The working principle of this technical solution is as follows: it is known that redox reactions of Fe(III) / Fe(II) and Mo(VI) / Mo(IV) can mutually promote each other, activating PMS to generate SO4·- and ·OH. Electrochemical analysis and XPS characterization further confirmed that the Fe(III) / Fe(II) and Mo(VI) / Mo(IV) redox reactions also exist in the CNTs@FeMoO4 activated PS system, as shown in equations 1-5.

[0018] ≡Fe(Ⅱ)+Mo(Ⅵ)→≡Fe(Ⅲ)+Mo(Ⅳ) Formula-1

[0019] ≡Fe(Ⅲ)+Mo(Ⅳ)→≡Fe(Ⅱ)+Mo(Ⅵ) Formula-2

[0020]

[0021]

[0022]

[0023] Furthermore, previous studies have demonstrated that the removal efficiency of 2,4-DCP in the CNTs / PS reaction system is affected by both... 1 O2 generation is controlled by direct electron transfer pathways mediated by carbonyl groups and defects on the CNT surface. On the one hand, studies have shown that PMS can accelerate the decomposition of cyclohexanone to form O2. 1 O2. In this study, since the sp2 carbon units of CNTs have a hexagonal network structure, they can be considered ketone compounds. Therefore, PS and CNTs can combine to form a structure similar to PMS, and generate a diethylene oxide adduct through hydroxylation and oxidation reactions; finally, S2O8 2- Molecular attack on the adduct of diethylene oxide, thereby generating 1 O2. During the degradation of organic matter, the PS and sp2 hybrid system combine to generate... 1 O2 is also produced at the same time. ·- As shown in equations 6-9. Subsequently, the active oxidizing agent can oxidize the organic pollutant BPAF adsorbed by the carbon nanotubes. This is consistent with the simultaneous detection of the presence of BPAF in the system in quenching experiments and EPR detection analyses. 1 O2 and O2 ·- Furthermore, in the EPR analysis over time, O2 was detected... ·- It changes little with reaction time, while 1 This is consistent with the result that O2 gradually increases with reaction time. Simultaneously, XPS C1s analysis before and after the reaction also confirmed that the C=O content on the surface of the composite material increased after the reaction, and new CF groups appeared, revealing that the O=CO functional groups on the material surface participated in the reaction. Furthermore, BPAF, as an electron donor, may have been adsorbed onto the catalyst surface, promoting the generation of non-radicals. 1 O2 accelerates the degradation of BPAF. Comparative analysis of FTIR spectra before and after the reaction revealed obvious OCO and CC bonds in the post-reaction FTIR spectrum, further confirming the presence of functional group oxidation in the reaction system. Ultimately, in the CNTs@FeMoO4 / PS system, BPAF is degraded by the free radical / non-free radical reactive substances (SO4) generated during the reaction. ·- , · OH and 1 O2 degrades into CO2, H2O or other small molecules.

[0024]

[0025]

[0026]

[0027] 2HOO · → 1 O2 + H2O2 (Formula 9)

[0028] To better implement the method of the present invention, in step (1), the mass percentage of the carbon nanotubes weighed is 0.5%.

[0029] To better implement the method of the present invention, the pH of the dilute hydrochloric acid solution in step (2) is further 2.0 to 2.5.

[0030] To better implement the method of the present invention, the stirring process in steps (3) and (4) is further completed by magnetic stirring using a magnetic stirrer.

[0031] To better implement the method of the present invention, the reactor in the thin (5) is further described as a stainless steel reactor with a polytetrafluoroethylene liner.

[0032] To better implement the method of the present invention, the process of cleaning the reaction solution in step (6) is further as follows: the reaction solution is centrifuged three times with deionized water and anhydrous ethanol at a speed of 6000 r / min.

[0033] A persulfate catalytic material is prepared by the above-described method for preparing a persulfate catalytic material.

[0034] An application of a persulfate catalytic material: using the aforementioned persulfate catalytic material as a catalyst for heterogeneous persulfate catalysis to achieve efficient degradation of pollutants.

[0035] The pollutant is at least one of emerging micropollutants such as bisphenol AF, 4,4'-ethylidene bisphenol, benzoic acid, 2,4-dichlorophenol, diethyl phthalate, and dimethyl phthalate.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] (1) This invention successfully synthesizes the composite material CNTs@FeMoO4 by doping CNTs into FeMoO4 through a simple hydrothermal synthesis method, and uses it as a catalyst for heterogeneous catalysis of persulfate to achieve efficient degradation of pollutants.

[0038] (2) This invention utilizes a composite material CNTs@FeMoO4 to catalyze the oxidation of persulfate. Compared to the FeMoO4 / PMS and Cu@FeMoO4 / PS systems, this system exhibits superior degradation performance for pollutants, particularly bisphenol AF (BPAF). When the initial dosage of CNTs@FeMoO4 is 100 mg / L, PS is 0.25 mM, BPAF is 5 mg / L, and the reaction time is 30 min, the BPAF removal rate reaches 86.9%, with a corresponding pseudo-first-order kinetic constant of 0.064 min⁻¹. The main factors affecting BPAF degradation efficiency were investigated, including the initial dosage of CNTs@FeMoO4, the initial dosage of PS, the initial pH of the reaction solution, and the reaction temperature. Experiments showed that when the initial pH of the solution is in the range of 3.0–9.0, the reaction system exhibits low sensitivity to the initial pH, resulting in minimal change in the BPAF degradation rate.

[0039] (3) This invention observed common anions (HCO3-) - Cl - NO3 - and SO4 2- The effect of CNTs@FeMoO4 / PS on BPAF removal. Experiments show that HCO3 - The inhibition of BPAF removal in the system was significant, while Cl... - The presence of SO4 has both promoting and inhibiting effects on the removal of BPAF from the system. 2- and NO3 - The impact on BPAF removal efficiency is small and can be ignored.

[0040] (4) The composite material CNTs@FeMoO4 prepared in this invention has certain stability and reusability, and the CNTs@FeMoO4 / PS system has certain universal applicability. It can effectively degrade a variety of organic pollutants, has good development prospects, and is suitable for widespread application. Attached Figure Description

[0041] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0042] Figure 1 The XPS full spectrum of the CNTs@FeMoO4 composite material prepared in this invention;

[0043] Figure 2 This is a fine spectrum of C1s in the CNTs@FeMoO4 composite material prepared in this invention;

[0044] Figure 3This is a fine spectrum of Fe 2p in the CNTs@FeMoO4 composite material prepared in this invention;

[0045] Figure 4 This is a fine spectrum of Mo 3d in the CNTs@FeMoO4 composite material prepared in this invention;

[0046] Figure 5 The XRD pattern of the CNTs@FeMoO4 composite material prepared in this invention;

[0047] Figure 6 The image shows the SEN image of the CNTs@FeMoO4 composite material prepared in this invention.

[0048] Figure 7 This is a partial enlarged SEM image of the CNTs@FeMoO4 composite material prepared in this invention;

[0049] Figure 8 Here is an HR-TEM image of the CNTs@FeMoO4 composite material prepared in this invention;

[0050] Figure 9 This is a magnified HR-TEM image of the CNTs@FeMoO4 composite material prepared in this invention;

[0051] Figure 10 This is the FTIR spectrum of CNTs@FeMoO4 before the reaction in this invention;

[0052] Figure 11 This is the FTIR spectrum of CNTs@FeMoO4 before the reaction in this invention;

[0053] Figure 12 The images show the Raman spectra of CNTs@FeMoO4 before and after the reaction in this invention.

[0054] Figure 13 The figure represents the removal rate of BPAF from water by CNTs@FeMoO4 catalysts prepared under different CNTs doping conditions in this invention.

[0055] Figure 14 The diagram shows the apparent degradation rate of BPAF removal from water by CNTs@FeMoO4 catalysts prepared under different CNTs doping conditions in this invention.

[0056] Figure 15 The figure shows the results of blank control experiments on the removal effect of BPAF in different reaction systems in this invention;

[0057] Figure 16The figure shows the results of comparative experiments on the removal effect of BPAF in different reaction systems of this invention, using similar catalytic materials.

[0058] Figure 17 This is an experimental analysis diagram of EtOH and TBA quenching in the CNTs@FeMoO4 / PS system of this invention;

[0059] Figure 18 Experimental analysis of NaN3 and L-histidine quenching in the CNTs@FeMoO4 / PS system

[0060] Figure 19 This is an experimental analysis diagram of CHCl3 quenching in the CNTs@FeMoO4 / PS system of this invention;

[0061] Figure 20 This is a comparison of the XPS full spectrum of the CNTs@FeMoO4 composite material prepared in this invention before and after the reaction;

[0062] Figure 21 This is a detailed spectral comparison of C1s in the CNTs@FeMoO4 composite material prepared in this invention before and after the reaction;

[0063] Figure 22 This is a detailed spectral comparison of Fe 2p in the CNTs@FeMoO4 composite material prepared in this invention before and after the reaction;

[0064] Figure 23 This is a detailed spectral comparison of Mo 3d in the CNTs@FeMoO4 composite material prepared in this invention before and after the reaction;

[0065] Figure 24 This is a diagram illustrating the reaction mechanism of the activation of persulfate by the CNTs@FeMoO4 composite material prepared in this invention;

[0066] Figure 25 For the generation of carbon nanotubes in this invention 1 The chemical reaction process of O2;

[0067] Figure 26 This is a line graph showing the removal of different target substances in the CNTs@FeMoO4 / PS system in this invention. Detailed Implementation

[0068] To make the objectives, process conditions, and advantages of the present invention clearer, the present invention will be further described in detail with reference to the following embodiments. However, the embodiments of the present invention are not limited thereto. Various substitutions and modifications can be made based on common technical knowledge and conventional means in the art without departing from the above-described technical concept of the present invention, and all such substitutions and modifications should be included within the scope of the present invention. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0069] Example 1:

[0070] This embodiment provides a method for preparing a persulfate catalytic material, which involves doping carbon nanotubes into ferric molybdate via hydrothermal synthesis to form a composite material. The specific preparation process includes the following steps:

[0071] (1) Weigh out the carbon nanotubes for later use;

[0072] (2) Place the weighed carbon nanotubes into a dilute hydrochloric acid solution and sonicate for 15 minutes to obtain a suspension.

[0073] (3) Add NaMoO4·2H2O to the obtained suspension solution, stir to dissolve, and obtain a mixed solution;

[0074] (4) Add FeSO4·5H2O to the prepared mixed solution, control the temperature at 25℃, and continue stirring for 15 min to obtain the reaction solution;

[0075] (5) Pour the well-mixed reaction solution into the reaction vessel, then place the reaction vessel into a forced-air drying oven and keep it at 180°C for 4 hours;

[0076] (6) After the reactor cools down to room temperature, remove the reaction solution and clean it.

[0077] Wash three times with deionized water and anhydrous ethanol at a speed of 6000 r / min;

[0078] (7) Place the centrifuged product into a forced-air drying oven and dry it at 60°C for 16 hours;

[0079] (8) After the dried product is ground into powder, it is obtained.

[0080] XPS characterization of the CNTs@FeMoO4 composite material before and after the reaction further revealed the electron transfer mechanism of Fe, Mo, and C elements during the oxidation process. The elemental composition of the composite material remained unchanged before and after the reaction, but the structure of the carbon nanotubes in the composite material may have undergone certain transformations, such as… Figure 20As shown. The C1s spectrum of CNTs@FeMoO4 before the reaction shows that the carbon element is mainly unsaturated carbon (284.8 eV, 84.59%, C=C or CC), with a relatively low carbonyl content (286.48 eV, 8.56%, C=O) and a relatively low carboxyl content (288.88 eV, 6.86%, -COOH). However, the C1s spectrum analysis of CNTs@FeMoO4 after the reaction shows that although the carbon element is still mainly unsaturated carbon (284.8 eV, 72.87%, C=C or CC), the contents of unsaturated carbon and carboxyl groups (288.89 eV, 4.02%, O=CO) have decreased. Conversely, the carbonyl content has increased to 16.27% (286.38 eV, C=O), and the analysis shows that the material surface contains CF (292.67 eV, 6.84%). Figure 21 As shown in the figure. This indicates that the carboxyl groups in the carbon nanotubes in the reaction system may participate in the oxidation process, and due to the presence of this structure, the CF bonds of some BPAF molecules are broken, promoting the oxidative decomposition of BPAF. Figure 22 The results show that Fe2p before and after the reaction... 3 / 2 The Fe(III) and Fe(II) compositions in the spectrum also changed. Before the reaction, the atomic compositions of Fe(III) and Fe(II) were 61.01% and 38.99%, respectively; after the reaction, they became 74.91% and 25.06%, respectively, indicating that an alternation of Fe(III) / Fe(II) occurred on the catalyst surface, promoting the activation of PS. Furthermore, the spectra of Mo3d before and after the reaction, such as... Figure 23 The changes were small, and the Mo 3d content before and after the reaction was similar. 3 / 2 and Mo 3d 5 / 2 The relative contributions changed from 40.1% and 59.9% to 53.1% and 46.9%, respectively. Literature indicates that the presence of Mo facilitates electron transfer between Fe ions. Therefore, this small change suggests the possible existence of Fe(III) / Fe(II) and Mo(VI) / Mo(IV) redox cycles in the system, promoting the oxidative removal of BPAF.

[0081] The catalytic mechanism by which CNTs@FeMoO4 activates PS during the reaction process may include both radical and non-radical pathways, such as... Figure 24 As shown.

[0082] It is known that redox reactions of Fe(III) / Fe(II) and Mo(VI) / Mo(IV) can mutually promote each other, activating PMS to generate SO4·- and ·OH. Electrochemical analysis and XPS characterization further confirmed that the Fe(III) / Fe(II) and Mo(VI) / Mo(IV) redox reactions also exist in the CNTs@FeMoO4 activated PS system, as shown in equations 1–5.

[0083] ≡Fe(Ⅱ)+Mo(Ⅵ)→≡Fe(Ⅲ)+Mo(Ⅳ) Formula-10

[0084] ≡Fe(Ⅲ)+Mo(Ⅳ)→≡Fe(Ⅱ)+Mo(Ⅵ) Formula-11

[0085]

[0086]

[0087]

[0088] Furthermore, previous studies have demonstrated that the removal efficiency of 2,4-DCP in the CNTs / PS reaction system is affected by both... 1 O2 generation is controlled by direct electron transfer pathways mediated by carbonyl groups and defects on the CNT surface. On the one hand, studies have shown that PMS can accelerate the decomposition of cyclohexanone to form O2. 1 O2. In this study, since the sp2 carbon units of CNTs have a hexagonal network structure, they can be considered ketone compounds. Therefore, PS and CNTs can combine to form a structure similar to PMS, and generate a diethylene oxide adduct through hydroxylation and oxidation reactions; finally, S2O8 2- Molecular attack on the adduct of diethylene oxide, thereby generating 1 O2, such as Figure 25 As shown. During the degradation of organic matter, the PS and sp2 hybrid system combine to produce... 1 O2 is also produced at the same time. ·- As shown in equations 6-9. Subsequently, the active oxidizing agent can oxidize the organic pollutant BPAF adsorbed by the carbon nanotubes. This is consistent with the simultaneous detection of the presence of BPAF in the system in quenching experiments and EPR detection analyses. 1 O2 and O2 ·- Furthermore, in the EPR analysis over time, O2 was detected... ·- It changes little with reaction time, while 1 This is consistent with the result that O2 gradually increases with reaction time. Simultaneously, XPS C1s analysis before and after the reaction, such as... Figure 23 As shown, the C=O content on the surface of the composite material increases after the reaction, and new CF groups appear, revealing that the O=CO functional groups on the material surface participate in the reaction. Furthermore, BPAF, as an electron donor, may be adsorbed onto the catalyst surface, promoting the generation of non-radicals. 1O2 accelerates the degradation of BPAF. Comparative analysis of FTIR spectra before and after the reaction revealed obvious OCO and CC bonds in the post-reaction FTIR spectrum, further confirming the presence of functional group oxidation in the reaction system. Ultimately, in the CNTs@FeMoO4 / PS system, BPAF is degraded by the free radical / non-free radical reactive substances (SO4) generated during the reaction. ·- , · OH and 1 O2 degrades into CO2, H2O or other small molecules.

[0089]

[0090]

[0091]

[0092] 2HOO · → 1 O2 + H2O2 (Formula 18)

[0093] Example 2:

[0094] This embodiment, based on the above embodiments, verifies the surface elemental composition and valence state of the experimentally prepared CNTs@FeMoO4 composite material. XPS energy dispersive spectroscopy analysis was performed on the CNTs@FeMoO4 sample, and the analysis results are as follows: Figures 1-4 As shown.

[0095] according to Figure 1 For the full spectrum, according to Figure 1 It can be seen that the material mainly contains four elements: Fe, Mo, O and C. The main spectral peaks correspond to Fe 2p, Mo 3d, O 1s and C 1s, respectively. The atomic mass ratio of Fe, Mo, O and C is 7.01%:5.75%:35.73%:51.51%.

[0096] Figure 2 The image shows the fine spectrum of C1s. Peak splitting of the fine C1s spectrum yields three sub-peaks with binding energies at 284.80 eV, 286.48 eV, and 288.88 eV, corresponding to C=C / CC, C=O, and O=CO, respectively.

[0097] Figure 3The fine spectrum of Fe 2p shows that it splits into four pairs of sub-peaks. Binding energies at (711.62 eV, 724.89 eV) and (717.22 eV, 730.02 eV) indicate the presence of Fe(III) on the material surface. Binding energies at (714.24 eV, 727.49 eV) and (720.90 eV, 734.17 eV) indicate the presence of Fe(II) on the material surface. The surface atomic ratio of Fe(II) and Fe(III) ionic valence states is 61.01%:38.99%, indicating that the material surface mainly contains iron in the two valence states of Fe(III) and Fe(II).

[0098] Figure 4 The fine spectrum of Mo 3d is shown; the Mo 3d spectrum can be split into Mo 3d... 5 / 2 and Mo 3d 3 / 2 Two distinct main peaks are located at 232.52 eV and 235.66 eV respectively, with an energy level difference of 3.14 eV, indicating that the valence state of molybdenum is mainly +6.

[0099] The XPS characterization results above demonstrate that the CNTs@FeMoO4 composite material was successfully synthesized.

[0100] Example 3:

[0101] This embodiment observes and analyzes the morphology, structure, and lattice characteristics of the synthesized CNTs@FeMoO4 composite material.

[0102] The morphology, structure, and lattice characteristics of the synthesized CNTs@FeMoO4 composite material were observed and analyzed using XRD, SEM, and HR-TEM. The results are as follows: Figures 5-9 As shown.

[0103] Figure 5The XRD spectrum peaks at 2θ of 12.99°, 23.02°, 25.06°, 26.19°, 27.00°, 27.33°, 32.52°, 33.51°, 36.36°, 38.29°, and 39.69° are consistent with the lattice planes of β-FeMoO4 at (110), (021), (201), (220), (-112), (-202), (022), (-312), (400), (040), and (330), and show good agreement with the characteristic peaks of the standard card JCPDS#22-0628. In addition to the main diffraction peak, the other peaks at 13.99°, 25.45°, 28.17°, 31.58°, 42.82°, and 51.83° match the lattice planes of α-FeMoO4 at (110), (002), (220), (130), (330), and (421). Therefore, XRD results indicate that the synthesized CNTs@FeMoO4 composite material is mainly composed of β-FeMoO4 and some α-FeMoO4 impurities.

[0104] Figure 6 , Figure 7 SEM test results of the CNTs@FeMoO4 composite were presented. SEM images of CNTs@FeMoO4 at 10 μm magnification show that the synthesized composite material has a predominantly lamellar morphology, which differs significantly from the rod-shaped FeMoO4 prepared in Chapter 3. However, from... Figure 7 It can be seen that when the SEM image is magnified to 1μm, CNTs@FeMoO4 is mainly composed of rods and sheets.

[0105] Figure 8 , Figure 9 The HR-TEM test results of CNTs@FeMoO4 composite material were obtained. Figure 8 The results show that the doping mode of CNTs in the composite material is mainly bridging.

[307] Detailed HR-TEM observations were performed on the bridging points of the synthesized composite materials, such as... Figure 9 As shown, the atoms or atomic groups inside the material were found to be arranged in an ordered manner. Using a Fast Fourier Transform (FFT) algorithm and digital microscopy software, two lattice spacings were found in the composite material, 0.60 nm and 0.67 nm, respectively, which is consistent with the XRD analysis results. These results demonstrate that CNTs were successfully loaded onto FeMoO4 to obtain CNTs@FeMoO4 composite materials. Furthermore, the synthesized composite material contains both α-FeMoO4 and β-FeMoO4 crystalline forms.

[0106] Example 4:

[0107] This embodiment uses FTIR spectroscopy to analyze the changes in functional groups of the synthesized CNTs@FeMoO4 composite material before and after catalytic oxidation. The specific experimental conditions were: [PS]0 = 0.25 mM, [Catalyst]0 = 100 mg / L, [BPAF]0 = 5 mg / L, initial pH = 5.45 ± 0.2, T = 25 ± 1 °C, and reaction time 30 min.

[0108] Before the reaction, such as Figure 10 As shown, four strong absorption peaks appeared in the FTIR spectrum of CNTs@FeMoO4 before the reaction, located at 3186 cm⁻¹. -1 1614cm -1 915cm -1 630cm -1 Literature indicates it is located at 915cm. -1 630cm -1 The absorption peaks may be related to Fe4Mo3O 15 The vibrations of Mo=O and Fe-O-Mo in the distorted tetrahedron are related; located at 840 cm⁻¹ -1 1614cm -1 and 3186cm -1 The absorption peaks were attributed to the stretching of the CH and C=O bonds and the stretching vibration of the OH group in the water molecule, respectively, indicating that the CNTs-doped FeMoO4 was successful. The FTIR analysis results before the reaction further confirm the successful synthesis of CNTs@FeMoO4.

[0109] The FTIR analysis results after the reaction, such as Figure 11 As shown, at 1132cm -1 ~1254cm -1 Within the range and 1516cm -1 The presence of obvious fluctuation peaks indicates that the surface structure of the CNTs@FeMoO4 composite material after the reaction contains OCO and CC.

[0110] To further analyze the composition of the synthesized CNTs@FeMoO4 composite material, Raman analysis was performed on the materials before and after the reaction. The experimental conditions were: [PS]0 = 0.25 mM, [Catalyst]0 = 100 mg / L, [BPAF]0 = 5 mg / L, initial pH = 5.45 ± 0.2, T = 25 ± 1℃, and reaction time = 30 min. The experimental results are as follows: Figure 12 As shown, by fitting analysis of the D and G bands of the CNTs@FeMoO4 composite material before and after the reaction, the ratio of ID to IG before the reaction was 0.512, while the ratio of ID to IG after the reaction was 0.626, indicating that the material defects increased and the degree of graphitization decreased after the reaction.

[0111] Example 5:

[0112] In this embodiment, to verify the catalytic performance of the prepared CNTs@FeMoO4 composite material, the removal effect of BPAF in aqueous solution was used as the evaluation index. The effects of different CNTs doping conditions on the catalytic activation performance of CNTs@FeMoO4 were compared and analyzed. The experimental conditions were: [PS]0 = 0.25 mM, [Catalyst]0 = 100 mg / L, [BPAF]0 = 5 mg / L, initial pH = 5.45 ± 0.2, T = 25 ± 1 °C, and reaction time 30 min.

[0113] CNTs@FeMoO4 composites were prepared using carbon nanotubes (CNTs) of different masses. Based on the mass percentage of carbon nanotubes (CNTs), they were divided into five groups, A to E, as follows:

[0114] 0.1% CNTs@FeMoO4A group: The amount of CNTs used was 0.0039 g, and the doping mass percentage was 0.1 wt%.

[0115] 0.2% CNTs@FeMoO4 group: The amount of CNTs used was 0.0075 g, and the doping mass percentage was 0.2 wt%.

[0116] 0.5% CNTs@FeMoO4 group: The amount of CNTs used was 0.0099 g, and the doping mass percentage was 0.5 wt%.

[0117] 1% CNTs@FeMoO4 group: CNTs amount is 0.039g, and doping mass percentage is 1.0wt%;

[0118] 5% CNTs@FeMoO4 group: The amount of CNTs used was 0.1944 g, and the doping mass percentage was 5.0 wt%.

[0119] result Figure 13 As shown, CNT doping has a significant impact on the BPAF removal rate. Under the same experimental conditions, when the CNT doping amount is 0.5%, the CNTs@FeMoO4 catalyst prepared in group C has the highest BPAF removal efficiency for PS degradation, reaching 86.85%, followed by groups A and B. However, in groups D and E, where the CNT doping amount is increased, the BPAF removal efficiency rapidly decreases to 60.1% and 40.8%, respectively. The apparent rate constant k for BPAF degradation is also shown. obs The trend of change is the same as that of BPAF removal rate. When the doping concentration of CNTs is 0.5%, the maximum k is obtained. obs Value 0.064min -1Therefore, the optimal doping ratio of CNTs is 0.5%, and the CNTs@FeMoO4 catalyst prepared with the C group doping ratio exhibits the best performance.

[0120] Example 6:

[0121] This embodiment analyzes the activation of PS to remove BPAF from water by CNTs@FeMoO4 composite materials with optimal doping ratios prepared under different systems, in order to analyze the catalytic performance of CNTs@FeMoO4. The experimental conditions were: [PS]0 = 0.25 mM, [Catalyst]0 = 100 mg / L, [BPAF]0 = 5 mg / L, initial pH = 5.45 ± 0.2, T = 25 ± 1 °C, and reaction time 30 min.

[0122] Grouping:

[0123] PS group: The reaction system contains only persulfate;

[0124] CNTs@FeMoO4 group: The reaction system contains only CNTs@FeMoO4 composite material;

[0125] CNTs@FeMoO4 / PS group: The reaction system contains CNTs@FeMoO4 composite material and persulfate.

[0126] Experimental results are as follows Figure 15 As shown in the figure, adding PS alone has almost no removal effect. This is because although PS has its own oxidizing ability, the low dosage results in no removal effect in a short time. Adding CNTs@FeMoO4 composite material alone also shows little to no removal effect after 30 minutes of reaction. However, 3.8% of BPAF is removed after 2.5 minutes of reaction, but the removal rate quickly drops to zero. This may be due to weak adsorption and desorption on the surface of CNTs@FeMoO4 material in the first 5 minutes of reaction, but overall, the adsorption capacity of the prepared CNTs@FeMoO4 composite material for BPAF is very weak and negligible. However, when CNTs@FeMoO4 and PS are added simultaneously to the system, the BPAF removal rate reaches as high as 86.9% after 30 minutes of reaction, proving that the synthesized CNTs@FeMoO4 composite material has good catalytic activity.

[0127] Example 7:

[0128] This embodiment also compared and analyzed the removal efficiency of five reaction systems—PS, FeMoO4 / PS, CNTs@FeMoO4, CNTs / PS, and CNTs@FeMoO4 / PS—under the same conditions. The experimental conditions were: [PS]0 = 0.25 mM, [catalyst]0 = 100 mg / L, [BPAF]0 = 5 mg / L, initial pH = 5.45 ± 0.2, T = 25 ± 1 °C, and reaction time = 30 min.

[0129] PS group: The reaction system is CNTs / PS;

[0130] CNTs / PS group: The reaction system is FeMoO4 / PS;

[0131] FeMoO4 / PS group: The reaction system is FeMoO4 / PMS;

[0132] CNTs@FeMoO4 group: The reaction system is Cu@FeMoO4 / PS;

[0133] CNTs@FeMoO4 / PS group: The reaction system is CNTs@FeMoO4 / PS.

[0134] Experimental results are as follows Figure 16 As shown in the figure, under the same conditions, the removal rates of the four reaction systems—PS, FeMoO4 / PS, CNTs@FeMoO4, and CNTs / PS—were 2.4%, 41.5%, 3.5%, and 30.8%, respectively, all significantly lower than the 85.6% of the CNTs@FeMoO4 / PS reaction system. These experimental phenomena demonstrate that the CNTs@FeMoO4 catalyst exhibits excellent performance in activating PS to degrade BPAF.

[0135] Example 8:

[0136] In this embodiment, anhydrous ethanol (EtOH) and tert-butanol (TBA) were selected as quenchers to identify the main active species that may be generated in the CNTs@FeMoO4 / PS system during the reaction. The experimental conditions were: [PS]0 = 0.25 mM, [CNTs@FeMoO4]0 = 100 mg / L, [BPAF]0 = 5 mg / L, initial pH = 5.45 ± 0.2, T = 25 ± 1 °C, and reaction time = 30 min.

[0137] Anhydrous ethanol (EtOH) can react with SO4. ·- , · OH reacts rapidly, therefore it can be used as SO4. ·- ·OH quenchers; tert-butanol (TBA) can react rapidly with ·OH and act as a ·OH quencher.

[0138] The experimental procedure is as follows:

[0139] Under controlled experimental conditions, different concentrations (5 mM, 12.5 mM, 25 mM) of EtOH were added to the reaction solution, and the experimental results are as follows. Figure 17 As shown, after the reaction, the removal rate of BPAF decreased from 86.9% to 28.6%, 14.8%, and 11.5%, respectively, while the pseudo-first-order reaction rate constant k... obs Also from 0.064min -1 It rapidly decreased to 0.01 min. -1 0.004min -1 0.003min -1 This indicates that SO4 ·- ·OH and ·OH are likely the main active substances in the CNTs@FeMoO4 / PS reaction system.

[0140] When different concentrations (5 mM, 12.5 mM, 25 mM) of TBA were added as quenchers, the removal efficiency of BPAF decreased relatively little. Figure 17 As shown, the percentages decreased to 82.1%, 71.3%, and 66.3% respectively, indicating that even with the addition of excessive TBA, BPAF degradation could not be completely inhibited. Experimental results also indicate that SO42- is present in the CNTs@FeMoO4 / PS reaction system. ·- and · OH and SO42- together play a significant role in the oxidative degradation of BPAF. ·- It may play a very crucial role.

[0141] Example 9:

[0142] In this embodiment, sodium azide (NaN3) and L-histidine were selected as... 1 O2 quenchers were used to investigate whether the system might contain O2 quenchers. 1 O2 is a non-free radical of oxidizing substances. Sodium azide (NaN3) and L-histidine are commonly used in experiments. 1 O2 quencher.

[0143] The experimental procedure is as follows:

[0144] Under controlled experimental conditions, the addition of 5 mM NaN3 or L-histidine to the reaction system significantly affected the degradation of BPAF in the system. Figure 18 As shown, their removal rates decreased to 8.13% and 17.8%, respectively, k obs The decrease was significant, reaching as low as 7.4 × 10⁻⁶. -4 min -1and 0.006min -1 This suggests that there is a high probability that the system contains [certain elements]. 1 O2.

[0145] Example 10:

[0146] In this embodiment, carbon trichloride (CHCl3) is selected as O2. ·- The quencher was used to investigate whether O2 might be present in the system. ·- These are non-free radicals of oxidizing agents. Carbon trichloride (CHCl3) can react with O2 in the reaction system. ·- It undergoes a chemical reaction and is often used as O2. ·- Quenching agent.

[0147] The experimental procedure is as follows:

[0148] First, add 5 mM and 12.5 mM CHCl3 as O2 respectively. ·- The quenching agent, experimental results are as follows Figure 19 As shown, its inhibitory effect on BPAF degradation was not significant. When the concentration of CHCl3 was further increased to 25 mM, the removal rate of BPAF only decreased by about 6%. obs The changes were basically consistent, indicating that CHCl3 had a relatively small inhibitory effect on BPAF degradation. This suggests that O2 may be generated in the system. ·- However, its contribution to BPAF degradation is relatively weak.

[0149] Example 11:

[0150] This example is intended to further verify the performance of the CNTs@FeMoO4 / PS system in oxidative degradation of pollutants. Six representative organic pollutants were selected as target compounds in the experiment: 4,4'-ethylidene bisphenol (EBP), benzoic acid (BA), 2,4-dichlorophenol (2,4-DCP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and rhodamine B (RhB). Their removal in the CNTs@FeMoO4 / PS system was tested. The experimental conditions were as follows: [PS]0 = 0.25 mM, [CNTs@FeMoO4]0 = 100 mg / L, [BPAF]0 = 14.9 mM (5 mg / L), [2,4-DCP]0 = [EBP]0 = [BA]0 = [DMP]0 = [DEP]0 = [RhB]0 = 14.9 μM, initial pH = 5.45 ± 0.2, T = 25 ± 1 ℃, and reaction time = 30 min.

[0151] Experimental results are as follows Figure 26As shown, the CNTs@FeMoO4 / PS system can efficiently degrade benzene ring organic compounds EBP, BA, 2,4-DCP, and common dye pollutants RhB, especially 2,4-DCP, whose degradation effect is significantly better than other target compounds. However, the degradation effect of the CNTs@FeMoO4 / PS system on DEP and DMP is relatively low compared to other target compounds, with a DEP removal rate of only about 47.7% and a DMP removal rate of only about 41.9%. Studies have shown that the activation pathways of PS include both free radical and non-free radical pathways, and compared to reaction systems dominated by free radicals, the non-free radical pathway exhibits a certain degree of selectivity in the oxidative degradation of organic pollutants. Literature reports indicate that DMP can be degraded by SO42-. ·- and · OH oxidation, its k(DMP, · OH)=4.0×10 9 M -1 s -1 ,but 1 O2 oxidation and degradation capabilities are very limited. [333-337] DEP can be converted by SO4. ·- It is oxidized simultaneously with ·OH, but k(DEP,·OH) is 3.7 × 10⁻⁶. 9 M -1 s -1 Compared to k(DEP,SO4) ·- = 6.4 ± 0.3 × 10 7 It is about two orders of magnitude higher, and non-radical pathways cannot oxidatively degrade DEP.

[338] This not only aligns with the experimental results of this study, but also indirectly demonstrates the coexistence of free radical and non-free radical pathways in the reaction system. It also indicates that the CNTs@FeMoO4 / PS system possesses the ability to oxidatively degrade various organic pollutants.

[0152] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a persulfate catalytic material, characterized in that, Carbon nanotubes are doped into ferric molybdate via hydrothermal synthesis to form a heterogeneous catalytic persulfate composite material. The specific preparation process includes the following steps: (1) Weigh out carbon nanotubes for later use. The mass percentage of the carbon nanotubes weighed is 0.5%. (2) Place the weighed carbon nanotubes into a dilute hydrochloric acid solution and sonicate for 15 min to obtain a suspension. (3) Add NaMoO4·2H2O to the obtained suspension, stir to dissolve, and obtain a mixed solution; (4) Add FeSO4·5H2O to the prepared mixed solution, control the temperature at 25℃, and continue stirring for 15 min to obtain the reaction solution; (5) Pour the well-mixed reaction solution into the reaction vessel, then place the reaction vessel in a forced-air drying oven and keep it at 180°C for 4 h; (6) After the reactor is cooled to room temperature, the reaction solution is removed and cleaned. The specific process for cleaning the reaction solution is as follows: centrifuge with deionized water and anhydrous ethanol three times at a speed of 6000 r / min. (7) Place the centrifuged product into a forced-air drying oven and dry it at 60°C for 16 h; (8) After the dried product is ground into powder, it is obtained.

2. The method for preparing a persulfate catalytic material according to claim 1, characterized in that, The pH of the dilute hydrochloric acid solution in step (2) is 2.0~2.

5.

3. The method for preparing a persulfate catalytic material according to claim 1, characterized in that, The stirring process in steps (3) and (4) is completed by magnetic stirring using a magnetic stirrer.

4. The method for preparing a persulfate catalytic material according to claim 1, characterized in that, The reactor in step (5) is a stainless steel reactor with a polytetrafluoroethylene liner.

5. A persulfate catalytic material, characterized in that, It is prepared by the method for preparing a persulfate catalytic material according to any one of claims 1 to 4.

6. An application of a persulfate catalytic material, characterized in that, Using the persulfate catalytic material described in claim 5 as a catalyst for heterogeneous persulfate catalysis, efficient degradation of pollutants can be achieved. When the persulfate catalytic material degrades pollutants, persulfate needs to be added. The pollutants being degraded include benzene ring organic compounds such as 4,4'-ethylenebisphenol, benzoic acid, and 2,4-dichlorophenol, as well as dye pollutants such as rhodamine B.

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