Bimetal oxide modified biochar material as well as preparation method and application thereof

Abstract

The invention provides a bimetallic oxide modified biochar material as well as a preparation method and application thereof, and belongs to the technical field of water pollution treatment. According to the invention, the biochar is used as a matrix, the active component is loaded by utilizing the rich pore structure of the biochar, pollutants can be adsorbed, and the catalytic activation performance can be improved by virtue of the excellent electron transfer capability; by doping nitrogen in the biochar, the electronic structure and the adsorption performance of the biochar can be optimized, so that the catalytic activity is improved; the regular structure of the biochar can be destroyed by coating ferroferric oxide, a rich surface structure is constructed, active sites are further exposed, and contact with pollutants is increased; through loading cuprous oxide, copper ions and iron ions interact with each other, so that electron transfer on the surface of the catalyst is improved, generation of free radicals is promoted, and the degradation efficiency of pollutants is improved; the nanowire-shaped cuprous oxide can increase the specific surface area of the material and further promote contact with pollutants.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a bimetallic oxide modified biochar material, its preparation method, and its application. Background Technology

[0002] Phthalic acid esters (PAEs) are common organic pollutants and a class of widely used plasticizers, with applications in areas such as daily life, building decoration, cleaning, and agricultural production.

[0003] The presence of ester side chains in the molecular structure of PAEs gives the materials high chemical stability, resulting in good flexibility and durability. However, this also makes them difficult to biodegrade. Because there are no covalent bonds between PAEs and plastics, they are easily released during product use, entering water bodies, soil, and air through atmospheric deposition and runoff infiltration, becoming a ubiquitous pollutant.

[0004] In water bodies, PAEs not only have a toxic cumulative effect but can also react with other chemicals in the water to generate more complex toxic compounds. Studies have shown that PAEs can interfere with the endocrine system of organisms, causing hormonal imbalances and potentially affecting human reproductive health, immune function, and nervous system development. Traditional wastewater treatment processes, such as adsorption degradation (loading active components such as iron and cobalt onto the surface of MOF materials), have low removal efficiency for PAEs, leading to their persistent presence in the water cycle and posing a serious threat to ecosystems and human health. Summary of the Invention

[0005] The purpose of this invention is to provide a bimetallic oxide-modified biochar material, its preparation method, and its applications. The bimetallic oxide-modified biochar material provided by this invention exhibits excellent degradation effects on low concentrations of PAEs in water.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a bimetallic oxide modified biochar material, comprising: nitrogen-doped biochar, Fe3O4 coated by the nitrogen-doped biochar, and Cu2O supported on the nitrogen-doped biochar; wherein the Cu2O is a nanowire structure.

[0007] This invention also provides a method for preparing the bimetallic oxide modified biochar material described in the above technical solution, comprising: Biomass, a water-soluble iron source, a water-soluble nitrogen source, and water are mixed and loaded to obtain a precursor; The precursor is pyrolyzed in an inert atmosphere to obtain iron-nitrogen modified biochar; the pyrolysis temperature is 600~800℃ and the pyrolysis time is 1~2h. The iron-nitrogen modified biochar, water-soluble copper source, and alkaline solution are mixed and subjected to a precipitation reaction, followed by the addition of a reducing agent to carry out a reduction reaction, thereby obtaining a bimetallic oxide modified biochar material; the reducing agent includes one or more of ascorbic acid, D-glucose, glycerol, and D-fructose.

[0008] Preferably, the mass ratio of iron to water-soluble nitrogen in the dry basis of the biomass and the water-soluble iron source is 1:(0.05~0.2):(3~5).

[0009] Preferably, the mass ratio of copper in the iron-nitrogen modified biochar to that in the water-soluble copper source is (1.0~1.5):1.

[0010] Preferably, the molar ratio of copper to reducing agent in the water-soluble copper source is 1:(0.2~0.6).

[0011] Preferably, the molar ratio of copper in the water-soluble copper source to alkali in the alkaline solution is 1:(2~8).

[0012] Preferably, the loading includes: evaporating the mixture obtained by mixing to dryness at a temperature of 60~80°C.

[0013] The present invention also provides the application of the bimetallic oxide modified biochar material described in the above technical solution in the degradation of organic pollutants in water, including: mixing the bimetallic oxide modified biochar material, persulfate, and water containing organic pollutants for catalytic degradation.

[0014] Preferably, the organic pollutant is a phthalate compound.

[0015] Preferably, the amount of the bimetallic oxide modified biochar material is 0.1~0.4 g / L, and the amount of persulfate is 0.2~1 g / L.

[0016] This invention provides a bimetallic oxide modified biochar material, comprising: nitrogen-doped biochar, Fe3O4 coated on the nitrogen-doped biochar, and Cu2O supported on the nitrogen-doped biochar; the Cu2O is a nanowire structure. This invention uses biochar as a matrix, utilizing its abundant porous structure to load active components and adsorb pollutants. Its excellent electron transfer capability enhances catalytic activation performance. By doping the biochar with nitrogen, the electronic structure and adsorption performance of the biochar are optimized, thereby improving catalytic activity. Coating with Fe3O4 disrupts the regular structure of the biochar, constructing a rich surface structure, further exposing active sites, and increasing contact with pollutants. By supporting Cu2O, the interaction between copper and iron ions promotes the redox cycles of Fe(II) / Fe(III) and Cu(I) / Cu(II), thereby improving electron transfer on the catalyst surface and promoting the generation of free radicals, thus increasing the degradation efficiency of pollutants. The nanowire-like Cu2O increases the specific surface area of ​​the material, further promoting contact with pollutants. The results of the examples show that the bimetallic oxide modified biochar material provided by the present invention has a degradation rate of more than 98% for 20 mg / L diethyl phthalate (DEP) within 60 min. Attached Figure Description

[0017] Figure 1 XRD patterns of different materials used in this invention; Figure 2 SEM images of different materials in this invention and elemental mapping diagram of Cu2O / Fe-N-BC in Example 1; Figure 3 The hysteresis loop of Cu2O / Fe-N-BC in Embodiment 1 of the present invention; Figure 4 The degradation curves of DEP by different materials of this invention are shown. Figure 5 The degradation curves of DEP at different catalytic degradation pH values ​​of Cu2O / Fe-N-BC in Example 1 of this invention are shown. Figure 6 The degradation curve and EPR spectrum of DEP by Cu2O / Fe-N-BC free radical quenching in Example 1 of this invention are shown. Figure 7 The degradation curve and recovery efficiency of Cu2O / Fe-N-BC in Example 1 of this invention are shown. Figure 8 The degradation curves of Cu2O / Fe-N-BC for different pollutants in Example 1 of this invention are shown. Figure 9 The degradation curve of Cu2O / Fe-N-BC on mixed pollutants in Example 1 of this invention is shown. Detailed Implementation

[0018] All raw materials used in this invention are not particularly limited in their source; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0019] There are no particular restrictions on the purity of any of the raw materials used in this invention, but industrially pure raw materials are preferred.

[0020] This invention provides a bimetallic oxide modified biochar material, comprising: nitrogen-doped biochar, Fe3O4 coated by the nitrogen-doped biochar, and Cu2O supported on the nitrogen-doped biochar; wherein the Cu2O is a nanowire structure.

[0021] The bimetallic oxide modified biochar material provided by this invention includes nitrogen-doped biochar.

[0022] This invention enhances the graphitization of biochar by doping it with nitrogen, thereby optimizing its electronic structure and adsorption properties and improving its catalytic activity.

[0023] The bimetallic oxide modified biochar material provided by the present invention also includes Fe3O4 coated with the nitrogen-doped biochar.

[0024] This invention can disrupt the regular structure of biochar by coating it with Fe3O4, thereby creating a rich surface structure, further exposing active sites, and increasing contact with pollutants. Fe3O4 also endows the material with magnetic responsiveness, which facilitates the recycling and reuse of the material.

[0025] The bimetallic oxide modified biochar material provided by the present invention also includes Cu2O loaded on the nitrogen-doped biochar.

[0026] In this invention, the Cu2O is a nanowire structure. By loading Cu2O onto nitrogen-doped biochar, the interaction between copper and iron ions promotes the redox cycles of Fe(II) / Fe(III) and Cu(I) / Cu(II), thereby improving electron transfer on the catalyst surface and promoting free radical generation, thus enhancing the degradation efficiency of pollutants. The nanowire structure of Cu2O can increase the specific surface area of ​​the material, further promoting contact with pollutants.

[0027] This invention uses biochar as a matrix, utilizing its abundant porous structure to load active components and adsorb pollutants. Its excellent electron transfer capability enhances catalytic activation performance. By doping the biochar with nitrogen, its electronic structure and adsorption properties are optimized, thereby improving catalytic activity. Coating with Fe3O4 disrupts the regular structure of the biochar, creating a rich surface structure that further exposes active sites and increases contact with pollutants. Loading with Cu2O promotes the redox cycle of Fe(II) / Fe(III) and Cu(I) / Cu(II) through the interaction of copper and iron ions, improving electron transfer on the catalyst surface and promoting free radical generation, thus increasing the degradation efficiency of pollutants. The nanowire-like Cu2O increases the specific surface area of ​​the material, further promoting contact with pollutants.

[0028] This invention also provides a method for preparing the bimetallic oxide modified biochar material described in the above technical solution, comprising: Biomass, a water-soluble iron source, a water-soluble nitrogen source, and water are mixed and loaded to obtain a precursor; The precursor is pyrolyzed in an inert atmosphere to obtain iron-nitrogen modified biochar; the pyrolysis temperature is 600~800℃ and the pyrolysis time is 1~2h. The iron-nitrogen modified biochar, water-soluble copper source, and alkaline solution are mixed and subjected to a precipitation reaction, followed by the addition of a reducing agent to carry out a reduction reaction, thereby obtaining a bimetallic oxide modified biochar material; the reducing agent includes one or more of ascorbic acid, D-glucose, glycerol, and D-fructose.

[0029] This invention loads a mixture of biomass, a water-soluble iron source, a water-soluble nitrogen source, and water to obtain a precursor.

[0030] In one embodiment of the present invention, the biomass can be waste biomass, specifically one or more of coffee grounds, corn stalks, rice husks, and sawdust. Using biomass as a raw material can reduce raw material costs.

[0031] As one embodiment of the present invention, the biomass can be washed, dried and ground before use to obtain biomass powder.

[0032] In one embodiment of the present invention, the water-soluble iron source can be one or more of ferric chloride, ferric nitrate, and ferrous sulfate; in an embodiment of the present invention, the water-soluble iron source is ferric chloride. All of the above-mentioned iron sources are common iron salts, and using these iron sources can reduce raw material costs.

[0033] In one embodiment of the present invention, the water-soluble nitrogen source can be one or more of dicyandiamide, urea, and melamine; in an embodiment of the present invention, the water-soluble nitrogen source is dicyandiamide. The above-mentioned nitrogen sources are all common nitrogen-containing compounds and do not contain elements other than carbon, hydrogen, oxygen, and nitrogen, which is beneficial for further improving the catalytic activity of the material.

[0034] In this invention, the preferred mass ratio of iron to water-soluble nitrogen in the dry biomass and water-soluble iron source is 1:(0.05~0.2):(3~5), more preferably 1:(0.1~0.2):4. Maintaining this mass ratio within the above range facilitates in-situ doping of nitrogen and in-situ loading of iron in the biochar, thereby further enhancing the catalytic activity of the material.

[0035] The present invention does not have a particular limitation on the amount of water used, as long as it can disperse the raw materials evenly.

[0036] In this invention, the loading preferably includes evaporating the resulting mixture to dryness. As one embodiment of the invention, the evaporation can be carried out under stirring conditions.

[0037] In this invention, the evaporation temperature is preferably 60-80°C, more preferably 65-75°C; as one embodiment of this invention, the evaporation temperature can be 63°C, 66°C, 69°C, 70°C, 73°C, 77°C, or 80°C. The evaporation process hydrolyzes the iron source, loading it onto the biomass in the form of oxides, thus uniformly dispersing the nitrogen source in the biomass; when the water-soluble iron source is ferrous iron, it can also be oxidized to obtain magnetite (Fe3O4); when the iron source is ferric iron, it will be partially reduced to obtain magnetite (Fe3O4); the evaporation temperature within the above range is beneficial for iron hydrolysis.

[0038] After obtaining the precursor, the present invention pyrolyzes the precursor in an inert atmosphere to obtain iron-nitrogen modified biochar.

[0039] In this invention, the pyrolysis temperature is 600~800℃, preferably 650~750℃; as one embodiment of this invention, the pyrolysis temperature can be 600℃, 630℃, 660℃, 680℃, 700℃, 730℃, 760℃, or 780℃. Pyrolysis decomposes biomass to obtain biochar; the nitrogen source decomposes, and nitrogen is in-situ doped into the biochar; Fe3O4 is in-situ coated into the biochar; when the pyrolysis temperature is within the above range, nitrogen can be in-situ doped into the biochar, and Fe3O4 can be in-situ coated into the biochar, forming a rich surface structure on the biochar surface and improving the catalytic activity of the material.

[0040] In one embodiment of the present invention, the heating rate of the pyrolysis can be 5°C / min.

[0041] In this invention, the pyrolysis time is 1-2 hours, preferably 1.3-1.6 hours. A pyrolysis time within this range ensures that the pyrolysis proceeds sufficiently.

[0042] In one embodiment of the present invention, the inert atmosphere may be a nitrogen atmosphere.

[0043] In one embodiment of the present invention, the pyrolysis can be carried out in a tubular furnace.

[0044] In one embodiment of the present invention, after the pyrolysis is completed, the product can be ground to obtain iron-nitrogen modified biochar.

[0045] After obtaining the iron-nitrogen modified biochar, the present invention mixes the iron-nitrogen modified biochar, water-soluble copper source and alkaline solution to carry out a precipitation reaction, and then adds a reducing agent to carry out a reduction reaction to obtain bimetallic oxide modified biochar material.

[0046] In one embodiment of the present invention, the water-soluble copper source can be one or more of copper nitrate, copper sulfate, and copper chloride; in an embodiment of the present invention, the water-soluble copper source is copper nitrate trihydrate. All of the above copper sources are common copper salts, and using these copper sources can reduce raw material costs.

[0047] In one embodiment of the present invention, the alkaline solution can be a sodium hydroxide solution or a potassium hydroxide solution; in the embodiments of the present invention, the alkaline solution is a sodium hydroxide solution. The present invention precipitates copper on the surface of iron-nitrogen modified biochar by adding alkali; using the above-mentioned alkaline solution is beneficial for copper precipitation.

[0048] In this invention, the preferred mass ratio of the iron-nitrogen modified biochar to copper in the water-soluble copper source is (1.0~1.5):1, more preferably (1.0~1.3):1. A mass ratio of the iron-nitrogen modified biochar to copper in the water-soluble copper source within the above range is beneficial for the mutual promotion between iron and copper, further enhancing the catalytic activity of the material.

[0049] In this invention, the molar ratio of copper in the water-soluble copper source to alkali in the alkaline solution is preferably 1:(2~8), more preferably 1:6; as one embodiment of this invention, the molar ratio of copper in the water-soluble copper source to alkali in the alkaline solution can be 1:4, 1:5, 1:6, 1:7, or 1:8. A ratio of copper in the water-soluble copper source to alkali in the alkaline solution within the above ranges is beneficial for copper precipitation.

[0050] In one embodiment of the present invention, the concentration of the alkaline solution can be 0.12 g / mL.

[0051] As one embodiment of the present invention, the precipitation reaction can be carried out by: first dispersing the iron-nitrogen modified biochar in water, then adding a water-soluble copper source, stirring for 30 minutes to allow copper ions to be fully adsorbed on the iron-nitrogen modified biochar, then adding an alkaline solution dropwise, and stirring for 30 minutes after the addition is completed to allow the copper to precipitate fully.

[0052] In this invention, the reducing agent includes one or more of ascorbic acid, D-glucose, glycerol, and D-fructose, preferably ascorbic acid. The above-mentioned reducing agent can reduce divalent copper to monovalent copper, but has a weak reducing effect on iron(III) oxide.

[0053] In this invention, the molar ratio of copper to reducing agent in the water-soluble copper source is preferably 1:(0.2~0.6), more preferably 1:(0.3~0.5). A molar ratio of copper to reducing agent within the above range is beneficial for the reduction of divalent copper.

[0054] In one embodiment of the present invention, the reducing agent can be dissolved in water first to obtain a reducing agent solution, and then added to the reaction system; the concentration of the reducing agent solution can be 0.044 g / mL.

[0055] In one embodiment of the present invention, the reduction reaction can be carried out under stirring conditions; the reduction reaction time can be 1-2 hours.

[0056] In one embodiment of the present invention, after the reduction reaction is completed, the reaction system can be centrifuged, washed, and dried sequentially to obtain bimetallic oxide modified biochar material; the washing can be performed by rinsing three times with deionized water; the drying can be performed by drying in an oven at 65°C for 12 hours. The present invention does not have particularly limited parameters for the centrifugation, as long as the solid products can be separated.

[0057] The preparation method provided by this invention has a wide range of raw material sources and low equipment requirements, which can reduce the preparation cost; the preparation process is simple and easy to control, which helps to ensure the quality of materials.

[0058] The present invention also provides the application of the bimetallic oxide modified biochar material described in the above technical solution in the degradation of organic pollutants in water, including: mixing the bimetallic oxide modified biochar material, persulfate, and water containing organic pollutants for catalytic degradation.

[0059] In this invention, the organic pollutant is a phthalate ester compound; as one embodiment of this invention, the phthalate ester pollutant may be one or more of DEP, dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP).

[0060] In this invention, the amount of the bimetallic oxide modified biochar material is preferably 0.1~0.4 g / L, more preferably 0.2~0.3 g / L. Using the bimetallic oxide modified biochar material within the above range is beneficial for exerting a catalytic effect and further improving the degradation efficiency.

[0061] In this invention, the amount of persulfate is preferably 0.2~1 g / L, more preferably 0.4~0.8 g / L; as one embodiment of this invention, the amount of persulfate can be 0.3 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, or 0.9 g / L. Using persulfate within the above range is beneficial for exerting the degradation effect and further improving the degradation efficiency.

[0062] In this invention, the pH value for catalytic degradation is preferably 2-11, more preferably 3-10; as one embodiment of this invention, the pH value for catalytic degradation can be 3, 4, 5, 6, 7, 8, 9, or 11. A pH value within the above range is beneficial for further improving the degradation effect.

[0063] The application method provided by this invention can effectively degrade phthalate pollutants in water.

[0064] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0065] Example 1 A bimetallic oxide modified biochar material is composed of nitrogen-doped biochar, Fe3O4 coated by the nitrogen-doped biochar, and Cu2O supported on the nitrogen-doped biochar; the Cu2O is a nanowire structure.

[0066] The preparation method is as follows: 1g of dried waste coffee grounds, 0.5g of ferric chloride, and 4.0g of dicyandiamide were added to 60mL of deionized water and stirred at 80℃ until the water evaporated to dryness to obtain a precursor. The precursor was placed in a tube furnace and heated to 700℃ at a rate of 5℃ / min under N2 atmosphere. It was pyrolyzed for 1h and then cooled naturally to obtain iron-nitrogen modified biochar, denoted as Fe-N-BC. Weigh 0.7g of the above Fe-N-BC and disperse it in 40mL of deionized water. Add 2.41g of copper nitrate trihydrate and stir for 30min to allow it to be fully adsorbed. Then, add 20mL of NaOH solution with a concentration of 0.12g / mL and stir for 30min to generate a blue Cu(OH)2 precipitate. Add 20mL of ascorbic acid solution with a concentration of 0.044g / mL and stir at room temperature for 1h to carry out the reduction reaction. The suspension gradually turns brick red. After the reaction is completed, centrifuge to collect the solid product, wash it three times with deionized water, and dry it in an oven at 65℃ for 12h to obtain the final product, bimetallic oxide modified biochar material, denoted as Cu2O / Fe-N-BC.

[0067] Comparative Example 1 A biochar is prepared by placing 1g of dry waste coffee grounds in a tube furnace and heating it to 700℃ at a rate of 5℃ / min under a N2 atmosphere, and then pyrolyzing it for 1h to obtain the biochar, denoted as BC.

[0068] Comparative Example 2 A nitrogen-doped biochar is prepared by adding 1g of dried waste coffee grounds and 4.0g of dicyandiamide to 60mL of deionized water, stirring at 80℃ until the water evaporates to dryness, obtaining a precursor, placing it in a tube furnace, heating it to 700℃ at a rate of 5℃ / min under N2 atmosphere, and pyrolyzing it for 1h to obtain the precursor, denoted as N-BC.

[0069] Comparative Example 3 A copper-modified biochar was prepared as follows: 0.7 g of BC prepared in Comparative Example 1 was weighed and dispersed in 40 mL of deionized water. 2.41 g of copper nitrate trihydrate was added and stirred for 30 min to allow for full adsorption. Subsequently, 20 mL of NaOH solution with a concentration of 0.12 g / mL was added dropwise and stirred for 30 min to generate a blue Cu(OH)2 precipitate. 20 mL of ascorbic acid solution with a concentration of 0.044 g / mL was added and stirred at room temperature for 1 h to carry out a reduction reaction. The suspension gradually turned brick red. After the reaction was completed, the solid product was collected by centrifugation, washed three times with deionized water, and dried in an oven at 65 °C for 12 h to obtain copper-modified biochar, denoted as Cu2O-BC.

[0070] Test Example 1 X-ray diffraction (XRD) was used to analyze the Fe-N-BC and Cu2O / Fe-N-BC provided in Example 1, the BC provided in Comparative Example 1, the N-BC provided in Comparative Example 2, the Cu2O-BC provided in Comparative Example 3, and commercially available Cu2O. The XRD patterns were obtained as follows: Figure 1 As shown.

[0071] from Figure 1It can be seen that the original biochar (BC) has a broad peak at 2θ = 23°, corresponding to the (002) plane of graphitic carbon; nitrogen doping enhances graphitization, shifting the peak from 23° to 26.4°, reflecting the change in the material's crystal structure; the diffraction peaks at 30.1°, 35.5°, 43.1°, 57.0°, and 62.6° were identified as (220), (311), (400), and (5) planes of Fe3O4 (PDF#98-000-0294). The diffraction peaks of Cu2O (PDF#98-000-0186) appear at 29.6°, 36.5°, 42.3°, 61.4° and 73.6°, corresponding to the (110), (111), (200), (220) and (311) crystal planes; the XRD pattern of Cu2O / Fe-N-BC shows the typical characteristic diffraction peaks of Cu2O and Fe3O4, confirming the presence of Cu2O and Fe3O4 in the material.

[0072] Test Example 2 The Fe-N-BC and Cu2O / Fe-N-BC provided in Example 1, and the BC and commercially available Cu2O provided in Comparative Example 1 were observed and elementally analyzed using scanning electron microscopy. SEM images were obtained, as shown below. Figure 2 As shown. Figure 2 In the diagram, (a) represents BC, (b) represents Fe-N-BC, (c) represents commercially available Cu2O, (d) represents Cu2O / Fe-N-BC, (e) represents Cu2O / Fe-N-BC, and (f) represents the EDS elemental mapping of Cu2O / Fe-N-BC.

[0073] from Figure 2 It can be seen that the original biochar (BC) exhibits an irregular, dense carbon structure. After doping BC with iron and nitrogen to obtain iron-nitrogen modified biochar (Fe-N-BC), the morphology of the catalyst changed significantly. The surface of the Fe-N-BC sample showed obvious collapse, forming many etching pits on the surface. This rough surface can promote effective contact between the material and the contaminants and provide more active sites exposed on the material surface to promote redox reactions. Commercially available Cu2O appears as irregularly shaped spherical particles with a rough surface and a diameter of about 1 μm. After further doping Fe-N-BC with copper, many nanowires were grown in situ on the porous three-dimensional structure of Cu2O / Fe-N-BC. These special morphologies and structures in Cu2O / Fe-N-BC are the result of the synergistic activation of Fe and N during calcination. Furthermore, a uniform distribution of elements C, O, N, Fe, and Cu was detected on the EDS mapping image of Cu2O / Fe-N-BC, providing further evidence for the successful doping of iron and nitrogen, as well as the successful dispersion of Cu2O nanoparticles on the Fe-N-BC surface.

[0074] Test Example 3 The magnetic properties of Cu2O / Fe-N-BC in Example 1 were tested using a vibrating sample magnetometer (VSM), and the results are as follows: Figure 3 As shown.

[0075] from Figure 3 As can be seen, the hysteresis loop exhibits an S-shaped curve, indicating that no residual magnetization was detected when the external magnetic field was removed; the magnetization curve without a hysteresis loop demonstrates superparamagnetic properties, with a saturation magnetization of 14.84 emu·g. -1 The catalyst exhibits excellent magnetic response to an external magnet. This means that the material can be easily and quickly separated from the solution, significantly reducing operating costs in practical applications.

[0076] Test Example 4 Catalytic degradation tests were conducted on Fe-N-BC and Cu2O / Fe-N-BC provided in Example 1, BC provided in Comparative Example 1, N-BC provided in Comparative Example 2, Cu2O-BC provided in Comparative Example 3, and commercially available Cu2O. The test method was as follows: 0.2 g / L of the test material was added to 50 mL of DEP wastewater with a concentration of 20 mg / L. The suspension was stirred for 30 min to establish adsorption-desorption equilibrium. Then, 0.3 g / L KHSO5 (PMS) was added to initiate the degradation experiment. At a specified time point, 1 mL of sample solution was taken and immediately mixed with 0.5 mL of methanol to terminate the reaction. Subsequently, the mixed solution was passed through a nylon filter membrane with a pore size of 0.22 μm to remove suspended particulate matter. The concentration of residual DEP in the water was quantitatively analyzed using a high-performance liquid chromatography (HPLC) system. The test results are as follows: Figure 4 As shown. Figure 4 The PMS only indicates that only KHSO5 is used, without a catalyst; Figure 4 In the figure, (a) is the degradation curve and (b) is the linear relationship of degradation efficiency.

[0077] from Figure 4 It can be seen that the Cu2O / Fe-N-BC / PMS system exhibits significant DEP removal efficiency, with a degradation rate exceeding 98% within 60 minutes, superior to other systems. The Cu2O / Fe-N-BC system demonstrates excellent catalytic reactivity. This performance improvement is mainly attributed to the introduction of Cu2O; the interaction between copper and iron ions promotes the redox cycles of Fe(II) / Fe(III) and Cu(I) / Cu(II), thereby improving electron transfer on the catalyst surface and promoting free radical generation.

[0078] Test Example 5 The Cu2O / Fe-N-BC provided in Example 1 was subjected to catalytic degradation tests at different pH values. The test method was the same as that in Example 4, and the results are as follows: Figure 5 As shown.

[0079] from Figure 5 It can be seen that the Cu2O / Fe-N-BC provided by the present invention has a DEP degradation rate of 96.1%, 85.0%, 98.9%, 84.5% and 81.5% in 60 min within the pH range of 3 to 11, respectively. The optimal degradation rate is found at pH 7. This indicates that the bimetallic oxide modified biochar material provided by the present invention has a wide range of applications.

[0080] Test Example 6 Quenching experiments and electron paramagnetic resonance characterization were performed on the Cu2O / Fe-N-BC / PMS system of Test Example 4. The results are as follows: Figure 6 As shown. Figure 6 (a) shows the degradation curves using different quenchers, and (b) shows the degradation curves of ·OH and SO4· − Free radical EPR spectrum, (c) is ·O2 − EPR spectrum of free radicals, (d) represents reactive oxygen species. 1 O2EPR spectrum.

[0081] from Figure 6 It can be seen that free radicals (·OH and SO4·) − ) pathways and non-free radicals ( 1 Both O2 and other pathways contribute to the degradation of DEP. 1 O2 was identified as the primary ROS.

[0082] Test Example 7 The Cu2O / Fe-N-BC provided in Example 1 was recycled according to the method in Test Example 4. Cu2O / Fe-N-BC was recovered by magnetic separation, washed with deionized water, and dried before being used in the next DEP degradation. The results are as follows. Figure 7 As shown.

[0083] from Figure 7 It can be seen that the catalyst can still maintain excellent catalytic performance after 10 consecutive cycles, and the degradation rate of DEP is still higher than 80%, indicating that it has good structural stability and durability.

[0084] Test Example 8 The Cu2O / Fe-N-BC provided in Example 1 was subjected to catalytic degradation tests for different pollutants according to the method in Test Example 4. The pollutants were replaced with DBP, DEHP, and a mixture of the three (total concentration of 20 mg / L), respectively. The results are as follows: Figure 8 , Figure 9 As shown.

[0085] from Figure 8It can be seen that the Cu2O / Fe-N-BC / PMS system has good catalytic degradation performance for all three PAE pollutants. Within 60 min, the system achieved degradation rates of 98%, 95.52% and 93.47% for DEP, DBP and DEHP, respectively. from Figure 9 It can be seen that for mixed pollutants, after 60 min, the degradation rates of DEP, DBP, and DEHP were 96.2%, 92.3%, and 91.5%, respectively. The degradation efficiency in the mixed solution was slightly lower than that in the single solution. This is attributed to the system being limited by the PMS concentration and ROS generation rate. DEP, DBP, and DEHP compete for free radicals during the reaction, leading to a slight decrease in the overall degradation rate. This indicates that the catalyst has a broad-spectrum removal capability for various PAE pollutants.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A bimetallic oxide modified biochar material, comprising: Nitrogen-doped biochar, Fe3O4 coated with the nitrogen-doped biochar, and Cu2O supported on the nitrogen-doped biochar; the Cu2O is a nanowire structure.

2. The method for preparing the bimetallic oxide modified biochar material according to claim 1, characterized in that, include: Biomass, a water-soluble iron source, a water-soluble nitrogen source, and water are mixed and loaded to obtain a precursor; The precursor is pyrolyzed in an inert atmosphere to obtain iron-nitrogen modified biochar; the pyrolysis temperature is 600~800℃ and the pyrolysis time is 1~2h. The iron-nitrogen modified biochar, water-soluble copper source, and alkaline solution are mixed and subjected to a precipitation reaction, followed by the addition of a reducing agent to carry out a reduction reaction, thereby obtaining a bimetallic oxide modified biochar material; the reducing agent includes one or more of ascorbic acid, D-glucose, glycerol, and D-fructose.

3. The preparation method according to claim 2, characterized in that, The mass ratio of iron to water-soluble nitrogen in the biomass dry basis and water-soluble iron source is 1:(0.05~0.2):(3~5).

4. The preparation method according to claim 2, characterized in that, The mass ratio of copper in the iron-nitrogen modified biochar to that in the water-soluble copper source is (1.0~1.5):

1.

5. The preparation method according to claim 2, characterized in that, The molar ratio of copper to reducing agent in the water-soluble copper source is 1:(0.2~0.6).

6. The preparation method according to claim 2, characterized in that, The molar ratio of copper in the water-soluble copper source to alkali in the alkaline solution is 1:(2~8).

7. The preparation method according to claim 2, characterized in that, The load includes: evaporating the mixture obtained by mixing to dryness at a temperature of 60~80℃.

8. The application of the bimetallic oxide modified biochar material according to claim 1 or the bimetallic oxide modified biochar material prepared by any one of claims 2 to 7 in the degradation of organic pollutants in water, characterized in that, include: The bimetallic oxide-modified biochar material, persulfate, and water containing organic pollutants were mixed for catalytic degradation.

9. The application according to claim 8, characterized in that, The organic pollutant is a phthalate compound.

10. The application according to claim 8, characterized in that, Based on the volume of water, the amount of the bimetallic oxide modified biochar material is 0.1~0.4 g / L, and the amount of persulfate is 0.2~1 g / L.

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