Oxygen-rich vacancy manganese dioxide magnetic carbon-based composite catalyst, preparation method thereof and application thereof in activated peroxymonosulfate degradation of bisphenol s

Abstract

The application discloses an oxygen-vacancy-rich manganese dioxide magnetic carbon-based composite catalyst and a preparation method and application thereof in activating peroxymonosulfate to degrade bisphenol S. Wheat straw is used as a biochar raw material to prepare magnetic biochar, which is dispersed into a MnSO4*H2O solution and stirred, KMnO4 solution is added and stirred, the obtained material is transferred into a hydrothermal high-pressure kettle with a quartz liner, the high-pressure kettle is then transferred to a set temperature, after the reaction is completed, the material in the high-pressure kettle is cooled to room temperature, the reacted material is then filtered, the filtered solid is separated through a magnetic field, the solid with magnetism is washed and dried to obtain a catalyst precursor, and the catalyst precursor is aged through an NH4Cl solution to obtain the composite catalyst MBMN rich in OVs. The MBMN composite catalyst prepared by the application has low raw material cost, simple preparation process and high practicability.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and in particular to an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst, its preparation method, and its application in the degradation of bisphenol S (BPS) by activated persulfate. Background Technology

[0002] Advanced oxidation processes based on sulfate radicals (SR-AOPs) are considered effective methods for degrading organic pollutants. Thermal activation, ultraviolet (UV) activation, ultrasonic (US) activation, alkali activation, transition metal activation, and carbonaceous material activation can all effectively activate persulfate (PMS, HSO5). - SO4 is produced 2- This process oxidizes organic pollutants into intermediate products, which are then mineralized into CO2, H2O, and inorganic carbonates.

[0003] Biochar (BC) is a green material produced by carbonizing biomass under limited oxygen conditions. It has a large specific surface area, abundant functional groups, and is readily available. However, the catalytic performance of raw biochar is poor and cannot meet the requirements of complex water pollution treatment. Transition metal catalysts for PMS activation are favored by researchers due to their high catalytic efficiency, simple operation, and lack of the need for additional energy. However, homogeneous transition metal catalysts are difficult to recover and prone to secondary pollution, limiting their further research and application. In contrast, heterogeneous catalysts, such as metal oxides, offer advantages such as convenient recovery, high stability, and reduced secondary pollution. Among various metal oxides, manganese-based materials have become a research hotspot for PMS activation in recent years due to their abundant resources, economic availability, low toxicity, and resistance to leaching.

[0004] Due to strict regulations on the use of bisphenol A (BPA), bisphenol S (BPS4, 40-sulfonyldiphenol) has been widely used as a safe alternative in plastics manufacturing, pharmaceuticals, and personal care products. It is also used as an additive in the production of pesticides, leather tanning agents, and resin flame retardants. BPS has a disruptive effect on the human endocrine system, exhibiting reproductive toxicity, genotoxicity, and cytotoxicity. Its long half-life makes it difficult to biodegrade in aquatic environments, posing both ecotoxicological effects and public health risks. BPS is frequently detected in aquatic environments and can also be found in human urine and breast milk serum. Traditional water treatment technologies (such as coagulation sedimentation and activated carbon adsorption) are inefficient at degrading and removing bisphenol S.

[0005] Therefore, this invention proposes an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst, its preparation method, and its application in the degradation of bisphenol S by activated persulfate. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide an oxygen-vacancy-rich manganese dioxide magnetic carbon-based composite catalyst (MBMN), its preparation method, and its application in the degradation of bisphenol S by activated persulfate. Based on its surface oxygen vacancy regulation mechanism, the MBMN catalyst successfully constructs a PMS-activated mediated BPS degradation pathway, exhibiting significant mineralization efficiency of organic pollutants. Furthermore, the MBMN composite catalyst is also magnetic, facilitating recovery and reducing costs.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst includes the following steps:

[0009] 1) First, the collected wheat straw biomass is pretreated, then the pretreated wheat straw biomass is crushed, and the crushed wheat straw biomass is pyrolyzed. The product obtained after pyrolysis is labeled as BC.

[0010] 2) Magnetization modification of BC by chemical precipitation: Weigh appropriate amounts of FeSO4·7H2O and Fe(NO3)3·9H2O according to stoichiometric ratio, dissolve them in ultrapure water, stir until completely dissolved, then add the BC sample obtained in step 1) and continue stirring. Transfer the mixture to a water bath, adjust the pH value to 10–11, and continue the reaction to allow the iron oxide to fully precipitate and be loaded onto the BC surface. After the reaction is completed, wash the obtained solid product repeatedly until neutral, dry and grind it to finally obtain magnetic biochar, denoted as MB.

[0011] 3) Disperse the MB obtained in step 2) into a MnSO4·H2O solution and stir. After stirring evenly, add KMnO4 solution and stir again. After stirring evenly, transfer the obtained material to a hydrothermal autoclave with a quartz lining. Then transfer the autoclave to the set temperature. After the reaction is completed, wait for the material in the autoclave to cool to room temperature. Then filter the material after the reaction. After the filtered solid is separated by a magnetic field, the magnetic solid is washed and dried to obtain the catalyst precursor, denoted as MBM. After the precursor is fully ground, weigh the ground MBM sample and place it in a beaker. Add NH4Cl solution and age it under water bath conditions. Then filter the aged material. Wash, dry and grind the filtered solid to obtain the MBMN composite catalyst.

[0012] Furthermore, the specific process of step 1) wheat straw biomass pretreatment is as follows:

[0013] The collected wheat straw biomass is repeatedly washed with water to remove the dead leaves and dust on the surface. Then it is placed in a drying oven at 100-110℃ for 25-35 minutes to kill the green, and then transferred to a drying condition at 60-80℃.

[0014] Further, in step 1), wheat straw biomass powder is weighed and placed in a ceramic boat, then transferred to a tube furnace. Under N2 atmosphere, the temperature is increased to 550-620℃ at a rate of 4-6℃ / min, and the mixture is kept at this temperature for 2.5-3.5h for pyrolysis. The resulting product is labeled as BC.

[0015] Further, in step 2), the mass of FeSO4·7H2O is 0.15~0.6g, the mass of Fe(NO3)3·9H2O is 0.4~1.6g, the volume of ultrapure water is 100mL, the amount of BC sample added is 0.1~0.3g, and the water bath temperature is 60~80℃.

[0016] Further, in step 3), the ratio of the mass of MB to the volume of MnSO4·H2O solution and the volume of KMnO4 solution is 1:100-200:100-200, with mass in g and volume in mL; wherein the concentration of MnSO4·H2O solution is 0.02-0.025 mol / L and the concentration of KMnO4 solution is 0.0015-0.002 mol / L.

[0017] Furthermore, in step 3), the temperature is set to 150-180℃ and the reaction time is 5-8h.

[0018] Further, in step 3), weigh 0.15-0.25 g of MBM sample and place it in a beaker, add 45-55 mL of 0.5-1.0 M NH4Cl solution, and age it in a water bath at 50-70℃ for 18-24 h.

[0019] This invention proposes an oxygen-rich vacancy manganese dioxide magnetic carbon-based composite catalyst prepared by the method described above.

[0020] This invention also proposes the application of the aforementioned oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst in the degradation of bisphenol S by activated persulfate.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1) This invention prepares a manganese dioxide magnetic carbon-based composite catalyst (MBMN) rich in OVs, which is used to activate PMS and construct an MBMN / PMS catalytic oxidation system. This effectively solves the problems of low oxidant utilization, narrow pH operating range, and large influence from water matrix in advanced oxidation technologies based on PMS. At the same time, it has good reusability, and OVs can be regenerated by chemical etching. The MBMN composite catalyst prepared by this invention has low raw material cost, simple preparation process, and strong practicality.

[0023] 2) This invention prepares magnetic biochar using wheat straw as the biochar raw material. The biochar is dispersed in a MnSO4·H2O solution and stirred until homogeneous. Then, a KMnO4 solution is added and stirred again until homogeneous. The resulting material is transferred to a hydrothermal autoclave with a quartz lining. The autoclave is then heated to a set temperature. After the reaction is complete, the material in the autoclave is cooled to room temperature. The reacted material is then filtered. The filtered solid is separated by a magnetic field. The magnetic solid is washed and dried to obtain a catalyst precursor. This precursor is then aged in NH4Cl solution to obtain a composite catalyst MBMN rich in OVs. After modification, MBMN has a larger specific surface area and generates abundant OVs, producing more active sites and significantly improving its activation performance. The MBMN composite catalyst prepared in this invention is applied to the activation of PMS for BPS degradation, and can completely remove BPS from the solution.

[0024] 3) The MBMN composite catalyst prepared by this invention has a certain magnetic properties, is easy to recover, and has good stability and reusability. It still has high catalytic activity after multiple catalytic activation PMS experiments. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation process of the catalyst of this invention.

[0026] Figure 2 The images show SEM images of different catalyst materials and HRTEM images of the MBMN composite catalyst of this invention. Figure 2 (a) in the image is the SEM image of the MB; Figure 2 (b) in the image is the SEM image of M; Figure 2 (c) in the image is the SEM image of MBM; Figure 2 (d) in the image is the SEM image of MBMN; Figure 2 (e) and Figure 2 (f) in the image are HRTEM images of the MBMN composite catalyst;

[0027] Figure 3 Raman spectra of different catalytic materials of this invention;

[0028] Figure 4 The N2 adsorption-desorption isotherms of different catalytic materials of this invention are shown below.

[0029] Figure 5 The pore size distribution curves of different catalyst materials in this invention are shown.

[0030] Figure 6 The following are FT-IR images of different catalyst materials of this invention;

[0031] Figure 7 High-resolution XPS spectra of MBM and MBMN of this invention; Figure 7 (a) in the figure is the XPS full spectrum of MBM and MBMN; Figure 7 (b) in the image represents the C 1s spectrum; Figure 7 (c) in the image represents the O 1s spectrum; Figure 7 (d) in the spectrum represents the N 1s spectrum; Figure 7 (e) in the image represents the Fe 2p spectrum; Figure 7 (f) in the spectrum represents the 2p spectrum of Mn.

[0032] Figure 8 The hysteresis regression curve of MBMN;

[0033] Figure 9 Adsorption curves of BPS for different materials;

[0034] Figure 10 Degradation of BPS under different systems;

[0035] Figure 11 The effect of different pH values ​​on BPS degradation;

[0036] Figure 12 The effect of different catalyst dosages on BPS degradation;

[0037] Figure 13 The impact of PMS dosage on BPS is explained. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the scope described.

[0039] refer to Figure 1 A method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst includes the following steps:

[0040] 1) First, the collected wheat straw biomass was pretreated. The pretreated wheat straw biomass was crushed using a plant pulverizer. Then, the wheat straw biomass powder was weighed and placed in a ceramic boat and transferred into a tube furnace. The furnace was heated to the set temperature under N2 atmosphere and kept at the temperature for pyrolysis. The product obtained after pyrolysis was labeled as BC.

[0041] 2) Magnetization modification of BC by chemical precipitation: Weigh appropriate amounts of FeSO4·7H2O and Fe(NO3)3·9H2O according to stoichiometric ratio, dissolve them in ultrapure water, stir until completely dissolved, then add the BC sample obtained in step 1) and continue stirring. Transfer the mixture to a water bath, adjust the pH value to 10–11, and continue the reaction to allow the iron oxide to fully precipitate and be loaded onto the BC surface. After the reaction is completed, wash the obtained solid product repeatedly until neutral, dry and grind it to finally obtain magnetic biochar, denoted as MB.

[0042] 3) Disperse the MB obtained in step 2) into a MnSO4·H2O solution and stir. After stirring evenly, add KMnO4 solution and stir again. After stirring evenly, transfer the obtained material to a hydrothermal autoclave with a quartz lining. Then transfer the autoclave to the set temperature. After the reaction is completed, wait for the material in the autoclave to cool to room temperature. Then filter the material after the reaction. After the filtered solid is separated by a magnetic field, the magnetic solid is washed and dried to obtain the catalyst precursor, denoted as MBM. After the precursor is fully ground, weigh the ground MBM sample and place it in a beaker. Add NH4Cl solution and age it under water bath conditions. Then filter the aged material. Wash, dry and grind the filtered solid to obtain the MBMN composite catalyst.

[0043] Example 1

[0044] 1) The collected wheat straw biomass was repeatedly washed with water, placed in a drying oven at 105℃ for 30 min to kill the green, then transferred to 60℃ to dry. Finally, the dried wheat straw was crushed using a plant pulverizer. An appropriate amount of powder was weighed and placed in a ceramic boat and transferred to a tube furnace. The temperature was raised to 600℃ at a rate of 5℃ / min under N2 atmosphere and kept at the temperature for 3 h for pyrolysis. The resulting product was labeled as BC.

[0045] 2) Weigh 0.240 g FeSO4·7H2O and 0.698 g Fe(NO3)3·9H2O, dissolve them in 100 mL of ultrapure water, and stir until completely dissolved. Add 0.20 g of BC sample and continue stirring. Transfer the mixture to a 70℃ water bath, adjust the pH to 10–11, and continue the reaction for 60 min to allow the iron oxides to fully precipitate and load onto the BC surface. Wash the obtained solid product repeatedly until neutral, dry and grind it to finally obtain magnetic biochar, denoted as MB.

[0046] 3) Disperse 0.2 g MB obtained in step 2) into 30 mL of 0.024 M MnSO4·H2O solution and stir for 20 min. Then add 30 mL of 0.0016 M KMnO4 solution and stir for 20 min. After stirring evenly, transfer the obtained material to a hydrothermal autoclave with a quartz lining. Then transfer the autoclave to 160℃ and react for 6 h. After the reaction is completed, let the material in the autoclave cool to room temperature. Then filter the material after the reaction. After the filtered solid is separated by a magnetic field, the magnetic solid is washed and dried to obtain the catalyst precursor, denoted as MBM. After the precursor is fully ground, accurately weigh 0.20 g MBM sample and place it in a beaker. Add 50 mL of 0.5 M NH4Cl solution and age it in a 60℃ water bath for 24 h. Then filter the aged material. Wash, dry and grind the filtered solid to obtain the MBMN composite catalyst.

[0047] Example 2

[0048] 1) The collected wheat straw biomass was repeatedly washed with water, placed in a drying oven at 105℃ for 30 min to kill the green, and then transferred to 60℃ for drying. Finally, the dried wheat straw was pulverized using a plant pulverizer. An appropriate amount of powder was weighed and placed in a ceramic boat, which was then transferred to a tube furnace. Under a N2 atmosphere, the temperature was increased to 600℃ at a rate of 5℃ / min and kept at this temperature for 3 h for pyrolysis. The resulting product was labeled BC.

[0049] 2) Weigh 0.240 g FeSO4·7H2O and 0.698 g Fe(NO3)3·9H2O, dissolve them in 100 mL of ultrapure water, and stir until completely dissolved. Add 0.20 g of BC sample and continue stirring. Transfer the mixture to a 70℃ water bath, adjust the pH to 10–11, and continue the reaction for 60 min to allow the iron oxides to fully precipitate and load onto the BC surface. Wash the obtained solid product repeatedly until neutral, dry and grind it to finally obtain magnetic biochar, denoted as MB.

[0050] 3) Disperse 0.2 g MB obtained in step 2) into 30 mL of 0.024 M MnSO4·H2O solution and stir for 20 min. Then add 30 mL of 0.0016 M KMnO4 solution and stir for 20 min. After stirring evenly, transfer the obtained material to a hydrothermal autoclave with a quartz lining. Then transfer the autoclave to 160℃ and react for 6 h. After the reaction is completed, let the material in the autoclave cool to room temperature. Then filter the material after the reaction. After the filtered solid is separated by a magnetic field, the magnetic solid is washed and dried to obtain the catalyst precursor, denoted as MBM. After the precursor is fully ground, accurately weigh 0.20 g MBM sample and place it in a beaker. Add 50 mL of 1.0 M NH4Cl solution and age it in a 60℃ water bath for 24 h. Then filter the aged material. Wash, dry and grind the filtered solid to obtain the MBMN composite catalyst.

[0051] Example 3

[0052] 1) The collected wheat straw biomass was repeatedly washed with water, placed in a drying oven at 105℃ for 30 min to kill the green, and then transferred to 60℃ for drying. Finally, the dried wheat straw was pulverized using a plant pulverizer. An appropriate amount of powder was weighed and placed in a ceramic boat, which was then transferred to a tube furnace. Under a N2 atmosphere, the temperature was increased to 600℃ at a rate of 5℃ / min and kept at this temperature for 3 h for pyrolysis. The resulting product was labeled BC.

[0053] 2) Weigh 0.240 g FeSO4·7H2O and 0.698 g Fe(NO3)3·9H2O, dissolve them in 100 mL of ultrapure water, and stir until completely dissolved. Add 0.20 g of BC sample and continue stirring. Transfer the mixture to a 70℃ water bath, adjust the pH to 10–11, and continue the reaction for 60 min to allow the iron oxides to fully precipitate and load onto the BC surface. Wash the obtained solid product repeatedly until neutral, dry and grind it to finally obtain magnetic biochar, denoted as MB.

[0054] 3) Disperse 0.2 g MB obtained in step 2) into 30 mL of 0.024 M MnSO4·H2O solution and stir for 20 min. Then add 30 mL of 0.0016 M KMnO4 solution and stir for 20 min. After stirring evenly, transfer the obtained material to a hydrothermal autoclave with a quartz lining. Then transfer the autoclave to 160℃ and react for 6 h. After the reaction is completed, let the material in the autoclave cool to room temperature. Then filter the material after the reaction. After the filtered solid is separated by a magnetic field, the magnetic solid is washed and dried to obtain the catalyst precursor, denoted as MBM. After the precursor is fully ground, accurately weigh 0.20 g MBM sample and place it in a beaker. Add 75 mL of 0.5 M NH4Cl solution and age it in a 60℃ water bath for 24 h. Then filter the aged material. Wash, dry and grind the filtered solid to obtain the MBMN composite catalyst.

[0055] Example 4

[0056] 1) The collected wheat straw biomass was repeatedly washed with water, placed in a drying oven at 105℃ for 30 min to kill the green, and then transferred to 60℃ for drying. Finally, the dried wheat straw was pulverized using a plant pulverizer. An appropriate amount of powder was weighed and placed in a ceramic boat, which was then transferred to a tube furnace. Under a N2 atmosphere, the temperature was increased to 600℃ at a rate of 5℃ / min and kept at this temperature for 3 h for pyrolysis. The resulting product was labeled BC.

[0057] 2) Weigh 0.240 g FeSO4·7H2O and 0.698 g Fe(NO3)3·9H2O, dissolve them in 100 mL of ultrapure water, and stir until completely dissolved. Add 0.20 g of BC sample and continue stirring. Transfer the mixture to a 70℃ water bath, adjust the pH to 10–11, and continue the reaction for 60 min to allow the iron oxides to fully precipitate and load onto the BC surface. Wash the obtained solid product repeatedly until neutral, dry and grind it to finally obtain magnetic biochar, denoted as MB.

[0058] 3) Disperse 0.2 g MB obtained in step 2) into 30 mL of 0.024 M MnSO4·H2O solution and stir for 20 min. Then add 30 mL of 0.0016 M KMnO4 solution and stir for 20 min. After stirring evenly, transfer the obtained material to a hydrothermal autoclave with a quartz lining. Then transfer the autoclave to 160℃ and react for 6 h. After the reaction is completed, let the material in the autoclave cool to room temperature. Then filter the material after the reaction. After the filtered solid is separated by a magnetic field, the magnetic solid is washed and dried to obtain the catalyst precursor, denoted as MBM. After the precursor is fully ground, accurately weigh 0.20 g MBM sample and place it in a beaker. Add 50 mL of 0.5 M NH4Cl solution and age it in a 60℃ water bath for 18 h. Then filter the aged material. Wash, dry and grind the filtered solid to obtain the MBMN composite catalyst.

[0059] Comparative Example 1

[0060] 1) The collected wheat straw biomass was repeatedly washed with water, placed in a drying oven at 105℃ for 30 min to kill the green, and then transferred to 60℃ for drying. Finally, the dried wheat straw was pulverized using a plant pulverizer. An appropriate amount of powder was weighed and placed in a ceramic boat, which was then transferred to a tube furnace. Under a N2 atmosphere, the temperature was increased to 600℃ at a rate of 5℃ / min and kept at this temperature for 3 h for pyrolysis. The resulting product was labeled BC.

[0061] 2) Weigh 0.240 g FeSO4·7H2O and 0.698 g Fe(NO3)3·9H2O, dissolve them in 100 mL of ultrapure water, and stir until completely dissolved. Add 0.20 g of BC sample and continue stirring. Transfer the mixture to a 70℃ water bath, adjust the pH to 10-11, and continue the reaction for 60 min to allow the iron oxide to fully precipitate and load onto the BC surface. Wash the obtained solid product repeatedly until neutral, dry and grind it to finally obtain magnetic biochar, denoted as MB.

[0062] Comparative Example 2

[0063] Weigh out 3.16 g of KMnO4 and 5.07 g of MnSO4·H2O respectively, dissolve each in 100 mL of deionized water, and stir until completely dissolved. Slowly add the KMnO4 solution to the MnSO4·H2O solution at a rate of 1~2 drops / second, and continue stirring the reaction at a constant temperature of 80℃ for 6 h to finally obtain the product MnO2, denoted as M.

[0064] Comparative Example 3

[0065] 0.20 g of MB obtained from Comparative Example 1 was dispersed in 30 mL of 0.024 M MnSO4·H2O solution and stirred thoroughly. Then, 30 mL of 0.0016 M KMnO4 solution was added and stirred thoroughly. After stirring evenly, the resulting material was transferred to a hydrothermal autoclave with a quartz lining. The autoclave was then transferred to 160 °C and reacted for 6 h. After the reaction was completed, the material in the autoclave was cooled to room temperature. The reacted material was then filtered. The filtered solid was separated by a magnetic field. The magnetic solid was washed and dried to obtain the catalyst precursor, denoted as MBM.

[0066] The catalysts prepared in Example 1 and Comparative Examples 1-3 were analyzed as follows:

[0067] Depend on Figure 2 It can be seen that observation Figure 2 In (a), the surface of MB is relatively rough with large particles attached to it, which is presumably Fe3O4 generated on the surface. This indicates that the magnetic modification of biochar was successful, which facilitates the separation, recycling and reuse of the material, and at the same time provides a good platform for loading MnO2. Figure 2 (b) is the SEM image of M, showing the morphology of the nanorods. They are relatively uniform in size, but some areas exhibit an aggregated state, which leads to a reduction in specific surface area and active sites, which is not conducive to the catalytic reaction. Figure 2 (c) is a SEM image of the MBM composite catalyst. Rod-shaped α-MnO2 is uniformly dispersed on the surface of magnetic biochar, indicating that there may be surface interaction between M and MB, and MB can reduce the aggregation of M. Figure 2 Image (d) in the image is a SEM image of the MBMN composite catalyst, after passing through NH4+. + After treatment, the M atoms on the MB surface become smaller and thinner; this phenomenon is attributed to NH4. + The etching of weak interlayer connections in [MnO6] octahedrons induces their growth along the two-dimensional direction and generates abundant OVs. Compared with MBM, the aggregation of nanoparticles in MBMN is effectively suppressed, and the effective specific surface area is significantly increased, which is more conducive to the activation of PMS. Figure 2 Image (e) in the image is a high-resolution transmission electron microscope (HRTEM) image of MBMN, showing some needle-like or rod-like crystal structures, with clearly visible lattice stripes. Figure 2 As shown in (f), the lattice spacing is approximately 0.2378 nm, corresponding to the (211) crystal plane of α-MnO2.

[0068] Depend on Figure 3 The graph shows that MBM is at 653 cm⁻¹ -1 The peak at that point represents the stretching vibration of the Mn-O bond in the [MnO6] octahedron, which occurs after passing through NH4+. 4+After modification, the intensity of this characteristic peak decreased, and a significant blue shift was observed. This indicates that NH 4+ Treatment can effectively increase the oxygen vacancies in MBM, thereby improving its catalytic performance. Notably, MBM at 361 cm⁻¹... -1 A weak peak appeared at that point. However, according to NH... 4 + After processing, the weak peak shifted and almost disappeared, indicating that after NH4+ processing... 4+ After processing, K + There is a loss. This phenomenon can be attributed to the abundant NH4+ in the aging solution. 4+ Not only did it replace the K between layers + Furthermore, it is adsorbed onto [MnO6] nanosheets.

[0069] Depend on Figure 4 It can be seen that the adsorption isotherms of these four materials all conform to the characteristics of type IV isotherms, and H3 type hysteresis loops appear in the relative pressure range (P / P0 = 0.6~0.99), indicating that each sample exhibits significant mesoporous distribution characteristics.

[0070] from Figure 5 It can be observed that the pore size of the four groups of samples is mainly distributed in the range of 0~50 nm, indicating that the hierarchical porous structure of the samples is between mesopores and micropores.

[0071] Depend on Figure 6 As can be seen from the Fourier transform infrared (FTIR) spectra of MBM and MBMN, the broad absorption peak of the -OH group after NH4Cl treatment showed almost no change compared to MBM, indicating that the -OH groups on the material surface were well preserved during the modification process. In the MBMN spectrum, the 1404 cm⁻¹ peak... -1 An NH4-like substance appeared nearby. + The absorption peak of NH4 indicates that + It coordinates with surface -OH groups through hydrogen bonding.

[0072] Figure 7 (a) shows the XPS full spectrum of MBM and MBMN of the present invention. By comparing the full spectrum, it can be seen that the XPS full spectrum of MBM shows the presence of characteristic peaks of C, O, Fe and Mn, while the MBMN sample modified with NH4Cl showed the presence of the N 1s characteristic peak, indicating that N element was successfully doped. Figure 7 (b) in the figure is the fine spectrum of C 1s of MBMN. The peaks with binding energies of 284.7, 285.8, and 288.3 eV correspond to the functional groups C=C, CO, and C=O, respectively. Figure 7(c) in the figure is the spectrum of O 1s, where the peaks at binding energies of 530.1, 531.2, 531.96 and 532.1 eV are respectively attributed to lattice oxygen (OL), oxygen vacancies (OVs) and surface adsorbed oxygen (OA). Figure 7 (d) is the N 1s spectrum, with peaks at 398.9, 400.2 and 401.2 eV corresponding to pyridine N, pyrrole N and graphite N, respectively. Figure 7 (e) in the spectrum represents the Fe 2p spectrum, and the anti-coiling peaks at 710.3 and 723.9 eV can be attributed to Fe. 2+ (2p) 3 / 2 ) and Fe 2+ (2p) 1 / 2 The peaks at 712.7 and 725.6 eV should be attributed to Fe. 3+ (2p) 3 / 2 ) and Fe 3+ (2p) 1 / 2 The fitted peaks at 718.2 and 732.8 eV are satellite peaks of Fe 2p. It is worth noting that after N doping, Fe... 2+ (MBMN was 47.55%, MBM was 36.34%) and Fe 3 + The content of MBMN (52.45%) and MBM (63.66%) has changed to some extent. Figure 7 (f) in the figure is the Mn 2p spectrum, Mn(2p) 3 / 2 ) and Mn(2p 1 / 2 The binding energies of the two peaks are 641.7–642 eV and 654.6–654.8 eV, respectively. Among them, Mn 2p... 3 / 2 It can be fitted to two peaks, with the peaks at 642.1 and 643.3 eV belonging to the surface Mn, respectively. 3+ and Mn 4+ Material. When the surface Mn 3+ / Mn 4+ The higher the proportion, the higher the OVs content.

[0073] Depend on Figure 8 As can be seen from the observation of the hysteresis regression curve (VSM), its saturation magnetization (Ms) value is 7.91 emu / g, which can reach the target of magnetic separation. This indicates that at least after the reaction, the application of a certain magnetic field can effectively separate the catalyst.

[0074] Table 1 BET Analysis of Four Materials

[0075] catalyst <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Total pore volume (cm 3 / g)]]> Average pore size (nm) MB 244.600 0.315 0.514 M 75.267 0.269 0.143 MBM 93.379 0.288 0.122 MBMN 98.330 0.311 0.127

[0076] By comparing Table 1, it can be clearly seen that, compared with MBM, the N-doped MBMN composite catalyst has a further increase in specific surface area and pore volume. These advantages allow MBMN to expose more active sites to adsorb PMS molecules, which is beneficial to the catalytic reaction and thus improves the degradation effect of BPS.

[0077] Application Example 1

[0078] Add 50 mg / L bisphenol S (BPS) solution to a 250 mL beaker, then add 0.5 g / L of different catalysts (M, MB, MBM, MBMN), and begin the adsorption experiment with magnetic stirring at 500 rpm. Figure 9 As shown, all materials reached adsorption equilibrium within 30 minutes. Among them, the original MnO2 (M) had the worst adsorption effect on BPS, removing only 5.65% of BPS, while magnetic biochar (MB) had the strongest adsorption capacity for BPS, effectively removing 8.82% of BPS.

[0079] This can be attributed to the high affinity of BPS for biochar. The adsorption capacity of the loaded material (MBM) gradually decreased, while the adsorption capacity of the material modified with NH4Cl (MBMN) slightly increased. This is likely because N doping increased its surface area and altered its pore structure.

[0080] Application Example 2

[0081] A 50 mg / L bisphenol S (BPS) solution was added to a 250 mL beaker, followed by the addition of 0.5 g / L of different catalysts (M, MB, MBM, MBMN). The mixture was then magnetically stirred at 500 rpm for 30 min. Under stirring, 1 mM PMS was added to conduct the BPS degradation experiment. The degradation curves are shown below. Figure 10 As shown, the BPS level decreased slightly when PMS was added alone. However, when PMS and MBMN were added simultaneously, BPS was completely degraded within 120 minutes. This indicates that MBMN effectively activates PMS, thereby efficiently catalyzing the degradation of BPS by PMS.

[0082] Application Example 3

[0083] A 50 mg / L bisphenol S (BPS) solution was added to a 250 mL beaker, followed by the addition of 0.5 g / L MBMN composite catalyst. Comparative experiments were conducted at pH values ​​of 3, 5, 7, 9, and 11, as well as the natural pH, to investigate the effect of pH on the catalytic effect. The experimental results are as follows: Figure 11As shown, BPS was completely degraded within 120 min at pH values ​​of 7 and 9. When the pH increased to 11, the degradation rate of BPS by the MBMN / PMS system decreased to 89.71%. This may be because, under alkaline conditions, SO42-... ·- Can react with OH - The rapid reaction generates ∙OH, which has low oxidizing power. When the pH value is reduced to 3 or 5, the degradation rate of BPS is 90.44% and 91.20%, respectively. It can be concluded that MBMN exhibits good PMS activation performance under both acidic and alkaline conditions, indicating that MBMN can adapt to the complex diversity of water bodies.

[0084] Application Example 4

[0085] A 50 mg / L bisphenol S (BPS) solution was added to a 250 mL beaker. Then, 0.0, 0.25, 0.5, 0.75, and 1.0 g / L MBMN composite catalysts were added, respectively. The mixture was then magnetically stirred at 500 rpm for 30 min. Finally, 1 mM PMS was added under stirring conditions to conduct a BPS degradation experiment. The degradation curves are shown below. Figure 12 As shown, in the MBMN-free system, only PMS acts on BPS alone, resulting in minimal degradation. In systems with lower catalyst concentrations, the removal rate of BPS is less than 90% within 120 minutes. When the MBMN concentration reaches 0.5 g / L, the degradation rate reaches 100% within 120 minutes. Further increasing the catalyst concentration does not significantly improve the degradation efficiency.

[0086] Application Example 5

[0087] A 50 mg / L bisphenol S (BPS) solution was added to a 250 mL beaker, followed by the addition of 0.5 g / L M BMN composite catalyst. The mixture was then magnetically stirred at 500 rpm for 30 min. Under stirring, 0.0, 0.5, 1, and 1.5 mM PMS were added respectively for degradation experiments. The experimental results are as follows: Figure 13 In the system without PMS, the removal of BPS was solely due to the adsorption of MBMN. When the PMS concentration was 0.5 mM, the removal rate of BPS was 90.89% within 120 min. When the concentration was increased to 1 mM and 1.5 mM, BPS could be completely removed within 120 min.

Claims

1. A method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst, characterized in that... Includes the following steps: 1) First, the collected wheat straw biomass is pretreated, then the pretreated wheat straw biomass is crushed, and the crushed wheat straw biomass is pyrolyzed. The product obtained after pyrolysis is labeled as BC. 2) Magnetization modification of BC by chemical precipitation: FeSO4·7H2O and Fe(NO3)3·9H2O were weighed according to the stoichiometric ratio, dissolved in ultrapure water, and stirred until completely dissolved. Then, the BC sample obtained in step 1) was added and stirred continuously. The mixture was transferred to a water bath, the pH was adjusted to 10–11, and the reaction continued to allow the iron oxide to fully precipitate and be loaded onto the BC surface. After the reaction was completed, the obtained solid product was washed, dried and ground to obtain magnetic biochar, denoted as MB. 3) Disperse the MB obtained in step 2) into a MnSO4·H2O solution and stir. After stirring evenly, add KMnO4 solution and stir again. After stirring evenly, transfer the obtained material to a hydrothermal autoclave with a quartz lining. Then transfer the autoclave to the set temperature. After the reaction is completed, wait for the material in the autoclave to cool to room temperature. Then filter the material after the reaction. After the filtered solid is separated by a magnetic field, the magnetic solid is washed and dried to obtain the catalyst precursor, denoted as MBM. After the precursor is fully ground, weigh the ground MBM sample and place it in a beaker. Add NH4Cl solution and age it under water bath conditions. Then filter the aged material. Wash, dry and grind the filtered solid to obtain the MBMN composite catalyst.

2. The method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst according to claim 1, characterized in that... Step 1) The specific process of wheat straw biomass pretreatment is as follows: The collected wheat straw biomass is repeatedly washed with water to remove the dead leaves and dust on the surface. Then it is placed in a drying oven at 100-110℃ for 25-35 minutes to kill the green, and then transferred to a drying condition at 60-80℃.

3. The method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst according to claim 1, characterized in that... In step 1), wheat straw biomass powder is weighed and placed in a ceramic boat, which is then transferred to a tube furnace. Under N2 atmosphere, the temperature is increased to 550-620℃ at a rate of 4-6℃ / min, and the mixture is kept at this temperature for 2.5-3.5h for pyrolysis. The resulting product is labeled as BC.

4. The method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst according to claim 1, characterized in that... In step 2), the mass of FeSO4·7H2O is 0.15~0.6g, the mass of Fe(NO3)3·9H2O is 0.4~1.6g, the volume of ultrapure water is 100mL, the amount of BC sample added is 0.1~0.3g, and the water bath temperature is 60~80℃.

5. The method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst according to claim 1, characterized in that... In step 3), the ratio of the mass of MB to the volume of MnSO4·H2O solution and the volume of KMnO4 solution is 1:100-200:100-200, with mass in g and volume in mL; the concentration of MnSO4·H2O solution is 0.02-0.025 mol / L, and the concentration of KMnO4 solution is 0.0015-0.002 mol / L.

6. The method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst according to claim 1, characterized in that... In step 3), the temperature is set to 150-180℃ and the reaction time is 5-8h.

7. The method for preparing an oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst according to claim 1, characterized in that... In step 3), weigh 0.15-0.25 g of MBM sample and place it in a beaker. Add 45-55 mL of 0.5-1.0 M NH4Cl solution and age it in a water bath at 50-70℃ for 18-24 h.

8. An oxygen-enriched manganese dioxide magnetic carbon-based composite catalyst prepared by the method according to any one of claims 1-7.

9. The application of the oxygen-vacancy-enriched manganese dioxide magnetic carbon-based composite catalyst as described in claim 8 in the degradation of bisphenol S by activated persulfate.

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