FeS2 / biochar nanocomposite material, and preparation method and application thereof

Abstract

The application belongs to the field of environmental functional materials and water treatment technology, and particularly relates to a FeS2 / biochar nanocomposite material, a preparation method and application thereof. The preparation method of the FeS2 / biochar nanocomposite material comprises the following steps: (1) limiting oxygen calcination of biochar raw materials at 500-900 DEG C for 2-8 hours, cooling to room temperature, and then putting into concentrated nitric acid for acidification treatment, washing, filtering and drying to obtain biochar; (2) mixing iron powder, sulfur powder and the biochar powder obtained in the step (1), adding dry grinding aids into a ball mill together, then adding wet grinding aids, ball milling, washing the ball milling product, centrifuging and drying to obtain the FeS2 / biochar nanocomposite material. The embedding and doping of elements are realized in the co-ball milling reaction process, Fe-C and S-C bonds are generated in addition to the basic chemical bonds of FeS2 and biochar, the reduction capacity of the composite material to Fe(III) and the hydrophilicity of the material are increased, the conductivity and the electron transfer capacity of the material are enhanced, and thus the Fenton performance of the material is further improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of environmental functional materials and water treatment technology, and particularly relates to a FeS2 / biochar nanocomposite material and a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing the understanding of the background of the application without admitting that such information forms prior art.

[0003] Fenton reaction is an important advanced oxidation technology (AOPs) which utilizes Fe 2+ Catalysis of H2O2 generates ·OH and other active oxygen species with strong oxidizing ability, which can achieve the oxidation removal of refractory organic pollutants. Traditional homogeneous Fenton technology uses soluble ferrous salt (such as ferrous sulfate, ferrous chloride, etc.) as iron source, and Fe(II) in it catalyzes H2O2 to generate ·OH, but its higher requirement for pH (pH = 3-5) makes the traditional homogeneous Fenton technology have a narrow application range. Moreover, Fe(III) generated after the reaction of Fe(II) cannot effectively catalyze H2O2 to generate ·OH, and the rate of Fe(III) reduction to Fe(II) is very slow, which makes it necessary to add a large amount of Fe(II) in practical application, resulting in the generation of a large amount of hazardous waste iron sludge. The above defects all limit the practical application of Fenton oxidation process.

[0004] Pyrite is the most abundant natural sulfide mineral in the earth's crust, which has been proved to have more excellent Fenton-like performance than other iron-containing minerals such as magnetite and goethite. However, the release rate of Fe(II) from natural pyrite is too slow, and the surface active sites of natural pyrite are less, and the core problem of slow conversion of Fe(III) to Fe(II) has not been effectively solved. Most of the current researches on pyrite Fenton system are focused on natural pyrite with or without purification pretreatment, and the disadvantages of natural minerals such as unsaturated iron-sulfur stoichiometric ratio, large amount of associated impurities and easy oxidation will inhibit its catalytic activity and life. In addition, the diversity of composition, structure and impurities of natural pyrite will also lead to differences in treatment results, which restricts its application in scientific research and industrial production. On this basis, how to obtain high-purity FeS2 catalyst and further modify it to expand its applicable pH range, control the dissolution rate of Fe(II), and further improve its Fenton performance is the key to expand the application of FeS2-based catalysts. SUMMARY

[0005] In order to overcome the above problems, the application provides a FeS2 / biochar nanocomposite material and a preparation method and application thereof. In the application, iron powder, sulfur powder and biochar (BC) with wide sources are used as raw materials to prepare the FeS2 / BC nanocomposite Fenton material with high purity and uniform mixing through a wet mechanical chemical synthesis process. The mechanical chemical reaction process does not need to add a protective gas, has large system yield and does not need high equipment requirement, and does not produce secondary pollution. The FeS2 / BC nanocomposite material prepared in the application has increased number of active sites on the surface, improved catalytic performance, can catalyze degradation of organic pollutants in an aqueous solution, and the FeS2 / BC nanocomposite Fenton material still has excellent degradation performance under high pH (pH=11) conditions, and improves the limitation that the traditional Fenton is only applicable under acidic conditions (pH=3-5).

[0006] In order to achieve the above technical purposes, the application adopts the following technical solutions:

[0007] In a first aspect of the application, a preparation method of a FeS2 / biochar nanocomposite material is provided, and the preparation method comprises:

[0008] (1) biochar raw materials are limitedly calcined at 500-900 DEG C for 2-8 h, and after cooling to room temperature, the biochar raw materials are put into concentrated nitric acid for acidification treatment, and after the acidification treatment, the biochar raw materials are washed, filtered and dried to obtain biochar powder materials;

[0009] (2) iron powder, sulfur powder and the biochar powder prepared in step (1) are mixed, the mixed materials and dry grinding aids are added into a ball mill, wet grinding aids are added, ball milling is performed, the ball milling product is washed after the ball milling, the product is collected by centrifugation, and after drying, the FeS2@BC nanocomposite material is obtained.

[0010] In a second aspect of the application, the FeS2@BC nanocomposite material prepared by the above preparation method is provided.

[0011] In a third aspect of the application, the above FeS2@BC nanocomposite material is applied to degradation of organic matters in wastewater.

[0012] The application has the following beneficial effects:

[0013] (1) the biochar as an electron donor, an electron shuttle and persistent free radicals (PFRs) can improve the conversion rate of Fe(III) to Fe(II) in the Fenton reaction, thereby improving the yield of ·OH.

[0014] (2) The ball milling reaction of iron powder, sulfur powder, biochar powder and dry grinding aid realizes the chemical synthesis of FeS2 nanomaterials on the one hand, and effectively reduces the size of FeS2 and biochar particles on the other hand, and a chimeric semi-coated structure of biochar and FeS2 nanoparticles is formed in the process of ball milling. The chimeric structure can improve the electrical conductivity of the material while maintaining the integrity of the composite material, and due to the electronegativity of biochar, the Zeta potential of the composite material is improved, so that the Fe released by FeS2 in the Fenton reaction process 2+ The chimeric semi-coated structure of carbon particles and the electronegativity of biochar can effectively avoid the excessive precipitation of Fe 2+ and the subsequent environmental problems caused by it.

[0015] (3) The chimeric doping of elements is realized in the process of co-milling of iron powder, sulfur powder and biochar powder. In addition to the basic chemical bonds (Fe-S, C-C) of FeS2 and biochar, the co-generated Fe-C and S-C bonds increase the ability of the composite material to reduce Fe(III) and the hydrophilicity of the material, enhancing its electrical conductivity and electron transfer ability, thereby further improving the Fenton performance of the material.

[0016] (4) In the process of co-milling of iron powder, sulfur powder and biochar powder, the atomic lattice defects of Fe, S and biochar are significantly improved due to the element chimeric, increasing the number of active sites on the surface of the catalyst and improving its catalytic performance.

[0017] (5) The FeS2@BC nanocomposite prepared by the present application not only improves the limitation of traditional Fenton which is only applicable in acidic conditions (pH = 3-5), but also effectively improves the mineralization effect of pollutants compared with the FeS2 Fenton system and the FeS2+BC Fenton system obtained by physical mixing, while realizing higher pH adaptability. The FeS2@BC nanocomposite prepared by the present application still maintains excellent degradation performance under high pH (pH = 11) conditions, and can achieve a sulfamethazine (SMM) degradation rate of more than 90% within 60 min. At the same time, the FeS2@BC nanocomposite prepared by the present application has excellent degradation effect on sulfadiazine (SDZ), methylene blue (MB) and other organic pollutants, and therefore has good universal applicability.

[0018] (6) The FeS2@BC nanocomposite prepared by the present application shows good degradation effect during repeated use, solving the defect that some high-performance catalysts cannot be used for a long time. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the provided drawings.

[0020] Figure 1 The electron microscope picture of the FeS2@BC nanocomposite material prepared in the embodiment 2 of the present application, wherein a is a scanning electron microscope (SEM) picture, and b is a transmission electron microscope (TEM) picture;

[0021] Figure 2 The EDS picture of the FeS2@BC nanocomposite material prepared in the embodiment 2 of the present application;

[0022] Figure 3 The Zeta potential and particle size distribution picture of the FeS2@BC nanocomposite material prepared in the embodiment 2 of the present application;

[0023] Figure 4 The XPS spectrum picture of the FeS2@BC nanocomposite material prepared in the embodiment 2 of the present application;

[0024] Figure 5 The XRD picture of the FeS2@BC nanocomposite material prepared in the embodiment 2 of the present application;

[0025] Figure 6 The degradation rate picture of the FeS2@BC nanocomposite material in degrading sulfonamide metformin in organic wastewater under different pH conditions in the experimental example 1 of the present application;

[0026] Figure 7 The degradation effect picture of the FeS2@BC nanocomposite material in cyclic use of degrading sulfonamide metformin in organic wastewater in the experimental example 1 of the present application;

[0027] Figure 8 The pH change picture of the solution when the FeS2@BC nanocomposite material degrades sulfonamide metformin in organic wastewater under different initial pH conditions in the experimental example 1 of the present application;

[0028] Figure 9 The degradation performance comparison picture of the FeS2@BC nanocomposite material on different organic pollutants in the experimental example 2 of the present application;

[0029] Figure 10 The Raman spectrum picture of the FeS2@BC nanocomposite material before and after catalytic degradation in the embodiment 3 of the present application, and the FeS2+BC composite material in the comparative example 2;

[0030] Figure 11Figure 3 is a comparison chart of SMM degradation performance of FeS2@BC nanocomposite material in Example 3 of the present application, FeS2 nanomaterial in Comparative Example 1, and FeS2+BC composite material in Comparative Example 2.

[0031] Figure 12 Figure 4 is a comparison chart of iron dissolution in the reaction process of FeS2@BC nanocomposite material in Example 3 of the present application, FeS2 nanomaterial in Comparative Example 1, and FeS2+BC composite material in Comparative Example 2, wherein a is FeS2 Fenton system, b is FeS2+BC Fenton system, and c is FeS2@BC Fenton system.

[0032] Figure 13 Figure 5 is a comparison chart of TOC removal performance of pollutants of FeS2@BC nanocomposite material in Example 3 of the present application, FeS2 nanomaterial in Comparative Example 1, and FeS2+BC composite material in Comparative Example 2. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0034] It is also important to note that the terms used herein are not intended to limit the particular embodiments of the present application disclosed in the specification. As used herein, unless otherwise clear from context, the singular forms "a," "an," and "the" are intended to include the plural forms as well, and it is further understood that the terms "comprising" and / or "including" when used in this specification intend for indication of presence of a feature, step, operation, device, component and / or combinations thereof.

[0035] In a first exemplary embodiment of the present application, a preparation method of FeS2 / biochar nanocomposite material is provided, and the preparation method comprises:

[0036] (1) biochar raw material is limitedly calcined at 500-900℃ for 2-8h, and after cooling to room temperature, the biochar raw material is put into concentrated nitric acid for acidification treatment, and after the acidification treatment, the biochar powder material is obtained after washing, filtering and drying;

[0037] (2) iron powder, sulfur powder and the biochar powder obtained in step (1) are mixed, and the mixed material is added into a ball mill together with dry grinding aid, and then wet grinding aid is added, and ball milling is performed, and after the ball milling, the ball milling product is washed, the product is collected by centrifugation, and after drying, the FeS2@BC nanocomposite material is obtained.

[0038] The acidification treatment by nitric acid can remove the alkaline substances and various organic impurities remaining in the biochar raw material after calcination, and the strong oxidizing property of nitric acid can enhance the oxygen-containing functional groups on the surface of the biochar, thereby improving the performance of the subsequent composite material.

[0039] In one or more embodiments, in step (1), the biochar raw material comprises one or more of bamboo charcoal, straw, and sawdust, preferably bamboo charcoal.

[0040] In one or more embodiments, in step (1), the biochar raw material is limited oxygen calcined at 700°C for 2h, and the control heating rate is 3-15°C / min, preferably 10°C / min.

[0041] In one or more embodiments, in step (1), an inert gas such as argon or helium is used as the protective gas, and the flow rate of the protective gas is 200-600mL / min, preferably 400mL / min.

[0042] In one or more embodiments, in step (1), the concentration of the concentrated nitric acid is 65%-70%, preferably 68%.

[0043] In one or more embodiments, in step (1), the acidification treatment is carried out at a temperature of 50-80°C, preferably 60°C, and the acidification treatment is carried out for 1-4h, preferably 2h.

[0044] In one or more embodiments, in step (1), the washing method is washing with distilled water until neutral.

[0045] In one or more embodiments, in step (2), the molar ratio of iron powder to sulfur powder is 1:2-2.2, preferably 1:2.1; and the mass ratio of iron powder to biochar is 6-8:1, preferably 7:1. The excess sulfur powder can inhibit the occurrence of oxidation reaction during the ball milling process, thereby preventing the deactivation of the product.

[0046] In one or more embodiments, in step (2), the dry grinding aid is one of Na2S, Na2S2O3, Na2SO4, or FeSO4, preferably Na2S. The selected dry grinding aid is a reducing substance, which can provide a reducing atmosphere during the ball milling reaction process, thereby inhibiting the occurrence of oxidation reaction during the ball milling process. In addition, the dry grinding aid can act as a solid grinding aid, thereby further refining the particles of the product.

[0047] In one or more embodiments, in step (2), the mass ratio of the mixed material to the dry grinding aid is 10-40:1, preferably 20:1.

[0048] In one or more embodiments, in the step (2), the ball-to-material ratio is 10-50:1, preferably 30:1.

[0049] In one or more embodiments, in the step (2), the wet grinding aid is ethanol or ethylene glycol, preferably ethanol.

[0050] In one or more embodiments, in the step (2), the volume of the wet grinding aid to the mass of the mixed material is 0.2-2 mL / 1 g, preferably 1 mL / g.

[0051] In one or more embodiments, in the step (2), the rotation speed of the ball mill is 300-600 r / min, preferably 400 r / min; the ball milling time is 24-72 h, preferably 48 h.

[0052] In one or more embodiments, in the step (2), the diameter of the steel ball in the ball mill is 2-10 mm, preferably 5 mm.

[0053] In one or more embodiments, in the step (2), the ball milling equipment is a high-energy ball mill, preferably a planetary high-energy ball mill.

[0054] In one or more embodiments, in the step (2), after the ball milling, the ball-milled product is washed by using oxygen-free water and anhydrous ethanol in sequence under the protection of inert gas. The oxygen-free water removes the dry grinding aid in the material, and the ethanol protects the material from oxidation. After the ball milling, the product is a nano-sized particle with high surface activation energy and high reaction activity. The protection of inert gas can prevent oxidation reaction and thus inactivation of the product.

[0055] In one or more embodiments, in the step (2), the drying condition is 60-100℃ for 20-40 h under the protection of inert gas, preferably 80℃ for 30 h.

[0056] In one or more embodiments, in the step (2), the dried product can be further subjected to heat treatment under a protective atmosphere to obtain the FeS2@BC nanocomposite material. The heat treatment temperature is 100-450℃, preferably 300℃; the heat treatment time is 1-8 h, preferably 4 h; and the protective gas flow rate is 100-400 mL / min, preferably 200 mL / min.

[0057] The second typical embodiment of the present application provides the FeS2@BC nanocomposite material prepared by the above preparation method.

[0058] In a third typical embodiment of the present application, the FeS2@BC nanocomposite is applied to degrade organic matter in wastewater.

[0059] In one or more embodiments, the organic matter includes sulfisomidine, sulfadiazine, and methylene blue.

[0060] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with specific examples.

[0061] Example 1 FeS2@BC nanocomposite

[0062] (1) Biomass raw material (bamboo charcoal) was placed in a vacuum tube furnace, the heating rate was controlled at 10℃ / min, the calcination temperature was 700℃, the calcination time was 2h, argon was used as the protective gas, the protective gas flow rate was 400mL / min, and the pyrolysis was performed to prepare the biochar material. The obtained sample was placed in 68%(wt%) concentrated nitric acid for acidification treatment, the acidification treatment temperature was 60℃, and the acidification treatment time was 2h. After acidification treatment, the biochar powder material was obtained by washing with distilled water until neutral, filtering and drying.

[0063] (2) Iron powder, sulfur powder and the biochar powder prepared in step (1) were mixed (wherein the molar ratio of Fe:S was 1:2.1, and the mass ratio of iron powder to biochar was 7:1), the mixed material and dry grinding aid Na2S were added into a planetary high-energy ball mill according to the mass ratio of 20:1, the steel ball diameter was 5mm, the ball-to-material ratio was 30:1, wet grinding aid ethanol was then added, ball milling was performed at a speed of 400r / min, and the ball milling time was 48h. After ball milling, the ball-milled product was collected by sequentially washing with oxygen-free water and anhydrous ethanol under inert gas protection, the product was collected by centrifugation, and then dried at 80℃ for 30h under inert gas protection. The FeS2@BC nanocomposite was obtained after drying.

[0064] Example 2 FeS2@BC nanocomposite

[0065] (1) Biomass raw material (bamboo charcoal) was placed in a vacuum tube furnace, the heating rate was controlled at 10℃ / min, the calcination temperature was 700℃, the calcination time was 2h, argon was used as the protective gas, the protective gas flow rate was 400mL / min, and the pyrolysis was performed to prepare the biochar material. The obtained sample was placed in 68%(wt%) concentrated nitric acid for acidification treatment, the acidification treatment temperature was 60℃, and the acidification treatment time was 2h. After acidification treatment, the biochar powder material was obtained by washing with distilled water until neutral, filtering and drying.

[0066] (2) Iron powder, sulfur powder and biochar powder prepared in step (1) are mixed (wherein the molar ratio of Fe:S = 1:2.1, and the mass ratio of iron powder to biochar is 7:1), and the mixed material is added into a planetary high-energy ball mill together with dry grinding aid Na2S at a mass ratio of 20:1, the steel ball diameter is 5 mm, the ball-to-material ratio is 30:1, and wet grinding aid ethanol is added afterwards, and ball milling is performed at a speed of 400 r / min; the ball milling time is 48 h. After ball milling, the ball-milled product is collected and washed with oxygen-free water and anhydrous ethanol under inert gas protection in sequence, the product is collected by centrifugation, and then dried, dried at 80°C for 30 h under inert gas protection, and then the material is heat-treated at 300°C for 3 h in a vacuum tube furnace under the protection of 200 mL / min argon to obtain FeS2@BC nanocomposite.

[0067] Example 3 Characterization of FeS2@BC nanocomposite

[0068] In this example, the FeS2@BC nanocomposite prepared in Example 2 is characterized, Figure 1 which are electron microscope images of the FeS2@BC nanocomposite, wherein a is a scanning electron microscope (SEM) image, and b is a transmission electron microscope (TEM) image; Figure 2 which are EDS images of the FeS2@BC nanocomposite. From the images, Figure 1 and Figure 2 It can be seen from the images that the biochar and FeS2 nanoparticles in the FeS2@BC nanocomposite are uniformly mixed, and form a chimeric semi-coated structure. Figure 3 which are Zeta potential and particle size distribution images of the FeS2@BC nanocomposite. From the images, Figure 3 It can be seen that the average particle size of the prepared composite material is about 200-300 nm, and the zero charge point is about 4.17. Due to the electronegativity of biochar, the Zeta potential of the composite material is improved, so that the Fe ions released from FeS2 in the Fenton reaction process of the composite material can be attached to the surface of the material, which can effectively avoid the excessive precipitation of Fe ions in the system and the subsequent environmental problems caused thereby.

[0069] Figure 4 which are XPS spectra of the FeS2@BC nanocomposite; during the co-ball milling reaction of iron powder, sulfur powder and biochar powder, chimeric doping of each element is achieved, in addition to the basic chemical bonds (Fe-S, C-C) of FeS2 and biochar, Fe-C and S-C bonds are also generated, which increases the ability of the composite material to reduce Fe(III) and the hydrophilicity of the material, enhances the conductivity and electron transfer ability of the material, and further improves the Fenton performance of the material.

[0070] Figure 5The image shows the XRD pattern of the FeS2@BC nanocomposite material; iron powder and sulfur powder react chemically to form pyrite-type FeS2.

[0071] Experimental Example 1: Removal of sulfamethoxypyrimidine from water using FeS2@BC nanocomposite materials

[0072] A 50 mg / L sulfamethoxypyrimidine solution was prepared at room temperature to simulate organic wastewater. The initial pH of the solution was adjusted to (3, 5, 7, 9, 11) using NaOH and HCl. The FeS2@BC nanocomposite material prepared in Example 2 (catalyst dosage 0.2 g / L) was added sequentially to the organic wastewater. After adsorption-desorption equilibrium was reached (30 min), 1.25 mM H2O2 was added, and the reaction was continued with stirring. The SMM concentration at different reaction times was determined by high-performance liquid chromatography (HPLC), and the SMM degradation rate was calculated. The results are shown below. Figure 6 As stated. From Figure 6 It can be seen that the FeS2@BC nanocomposite material prepared by this invention not only overcomes the limitation of traditional Fenton nanocomposites being applicable only under acidic conditions (pH=3-5), achieving adaptability to higher pH levels, but also effectively improves the degradation effect on pollutants. The FeS2@BC nanocomposite material prepared by this invention maintains excellent degradation performance even under high pH conditions (pH=11), achieving a degradation rate of over 90% for sulfamethoxypyrimidine (SMM) within 60 minutes.

[0073] The recycling performance of the FeS2@BC nanocomposite was tested, and the results are as follows: Figure 7 As shown in the figure. The results indicate that the FeS2@BC nanocomposite material exhibits good degradation performance in 8 cycles of use. The FeS2@BC nanocomposite material prepared in this invention demonstrates good degradation performance during repeated use, solving the defect that some high-performance catalysts cannot be used stably for a long time.

[0074] The pH of the mixed solution was also measured, and the results are as follows: Figure 8 As shown, the pH of the mixed solution after the reaction gradually became acidic, indicating that the FeS2@BC nanocomposite material in this invention has the ability to spontaneously adjust the pH of the solution system to acidic during the degradation reaction.

[0075] Experiment Example 2

[0076] Sulfamonomethoxine solution with a concentration of 50 mg / L, sulfadiazine (SDZ) solution with a concentration of 30 mg / L and methylene blue (MB) solution with a concentration of 100 mg / L were prepared at room temperature, and the initial pH of the system was adjusted to 5. FeS2@BC nanocomposites prepared in Example 2 (catalyst dosage 0.2 g / L) were added to the three kinds of organic wastewater solutions respectively, and after reaching adsorption-desorption equilibrium (30 min), 1.25 mM of H2O2 was added, and the stirring reaction was continuously carried out. The concentrations of SMM, SDZ and MB corresponding to different reaction times were determined by high performance liquid chromatography (HPLC), and the degradation rates of SMM, SDZ and MB were calculated, and the results are shown in Table 1. Figure 9 The results show that the FeS2@BC nanocomposites prepared by the application have excellent degradation effect on sulfadiazine (SDZ), methylene blue (MB) and other organic pollutants, and therefore have good universal applicability.

[0077] Preparation of FeS2 nanomaterial (without adding biochar)

[0078] Compared with Example 2, the preparation of biochar was not carried out, and only steps (2) and (3) were carried out. Iron powder and sulfur powder were mixed according to a molar ratio of 1:2.1, and the mixed material and dry grinding aid Na2S were added to a planetary high-energy ball mill according to a mass ratio of 20:1. Steel balls with a diameter of 5 mm were used, and the ball-to-material ratio was 30:1. Then wet grinding aid ethanol was added, and ball milling was carried out at a speed of 400 r / min. The ball milling time was 48 h. After ball milling, the collected ball milling product was washed with oxygen-free water and anhydrous ethanol under inert gas protection, and the product was collected by centrifugation. After drying, the material was placed in a vacuum tube furnace and heat-treated at 300℃ for 3 h under an inert gas atmosphere. The flow rate of the protective gas was 200 mL / min, and the final FeS2 nanomaterial was prepared.

[0079] Preparation of FeS2+BC physical composite material

[0080] Compared with Example 2, FeS2 was synthesized by ball milling alone, and biochar was ball milled alone. The preparation method of biochar is the same as that of Example 1, and the ball milling process of biochar is the same as that of Example 1. The method for synthesizing FeS2 by ball milling alone is the same as that of Comparative Example 1.

[0081] The ball-milled FeS2 and biochar were physically mixed using a maroon mortar to prepare a FeS2 and BC physical composite material (denoted as FeS2+BC).

[0082] Experimental Example 3

[0083] The Raman spectra of the FeS2@BC nanocomposite material in Example 2 before and after catalytic degradation, and the FeS2+BC physical composite material in Comparative Example 2 were detected, and the results are shown in Figure 10 D :I G The I 2+ value of the FeS2@BC composite material was significantly improved compared with the physical composite material, which was due to the fact that the element intercalation between Fe, S and biochar during the co-ball milling reaction of iron powder, sulfur powder and biochar powder also caused the atomic lattice defects to be significantly improved, which was beneficial to increase the number of active sites on the surface of the catalyst and improve the catalytic performance.

[0084] Experimental Example 4

[0085] The FeS2@BC nanocomposite material prepared in Example 2, the FeS2 nanomaterial in Comparative Example 1, and the FeS2+BC physical composite material in Comparative Example 2 were used to degrade sulfamonomethoxine in organic wastewater. As a comparative experiment, a comparative example of adding H2O2 to degrade pollutants after BC catalysis alone was introduced, and a comparative example of adding H2O2 to degrade pollutants without treatment was introduced.

[0086] At room temperature, a sulfamonomethoxine solution with a concentration of 50 mg / L was prepared and divided into 5 parts. The FeS2@BC nanocomposite material prepared in Example 2 (catalyst dosage 0.2 g / L), the FeS2 nanomaterial in Comparative Example 1 (catalyst dosage 0.2 g / L), the FeS2+BC physical composite material in Comparative Example 2 (catalyst dosage 0.2 g / L), and the biochar prepared in step (1) in Example 2 were added to the organic wastewater solution, respectively. Another part was not added with catalyst. After 30 min, 1.25 mM of H2O2 was added, and the stirring reaction was continuously carried out. The concentration of SMM corresponding to different reaction times was determined by high performance liquid chromatography (HPLC), and the degradation rate of SMM was calculated, and the results are shown in Figure 11 The results show that BC+H2O2 alone and H2O2 alone have no degradation effect on the pollutant SMM, the FeS2@BC+H2O2, FeS2+BC+H2O2 and FeS2+H2O2 systems all show degradation effect on the pollutant, and the FeS2@BC+H2O2 system has the best performance.

[0087] The Fe 2+ and total Fe dissolution amounts of the organic wastewater before and after adding the FeS2@BC nanocomposite material prepared in Example 2, the FeS2 nanomaterial in Comparative Example 1, and the FeS2+BC physical composite material in Comparative Example 2 were detected, and the results are shown in Figure 12 The results show that the Fe 2+and the total Fe dissolution amount is the least. This is mainly due to the chimeric semi-coating structure of the biochar and the FeS2 nanoparticles. The chimeric structure can improve the electrical conductivity of the material while maintaining the integrity of the composite material, and due to the electronegativity of the biochar, the Zeta potential of the composite material is improved, so that the Fe ions released by FeS2 in the Fenton reaction process of the composite material can be attached to the surface of the material. The chimeric semi-coating of the carbon particles and the electronegativity of the biochar synergistically act to effectively prevent the excessive precipitation of Fe ions in the system.

[0088] The TOC change in the organic wastewater added with the FeS2@BC nanocomposite prepared in Example 2, the FeS2 nanomaterial in Comparative Example 1, and the FeS2+BC physical composite material in Comparative Example 2 was detected respectively, and the results are shown in Figure 13 The results show that the FeS2@BC nanocomposite exhibits the best TOC removal effect compared with the FeS2 material and the FeS2+BC physical composite material.

[0089] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing FeS2 / biochar nanocomposite, characterized in that, The preparation method comprises: The biomass raw material is placed in a vacuum tube furnace, the heating rate is controlled to be 10°C / min, the calcination temperature is 700°C, the calcination time is 2h, argon is used as the protective gas, the flow rate of the protective gas is 400mL / min, and the pyrolysis is used to prepare the biochar material; the obtained sample is placed in 68wt% concentrated nitric acid for acidification treatment, the acidification treatment temperature is 60°C, the acidification treatment time is 2h; after the acidification treatment, the biochar powder material is obtained by washing with distilled water until neutral, filtering and drying; the biomass raw material is bamboo charcoal; (2) iron powder, sulfur powder and the biochar powder prepared in step (1) are mixed; the molar ratio of Fe:S is 1:2.1, and the mass ratio of the iron powder to the biochar is 7:1; the mixed material and dry grinding aid Na2S are added into a planetary high-energy ball mill according to a mass ratio of 20:1, the steel ball diameter is 5mm, the ball-to-material ratio is 30:1, wet grinding aid ethanol is then added, ball milling is performed, the ball milling speed is 400r / min, the ball milling time is 48h; after the ball milling, the ball milling product is collected by sequentially using oxygen-free water and anhydrous ethanol under inert gas protection, the product is collected by centrifugation, and then drying is performed, the material is dried at 80°C for 30h under inert gas protection, after the drying, the material is heat-treated at 300°C for 3h under 200mL / min argon protection in a vacuum tube furnace to obtain the FeS2@BC nanocomposite.

2. The FeS2@BC nanocomposite prepared by the preparation method of claim 1.

3. Application of the FeS2@BC nanocomposite of claim 2 in degrading organic matter in wastewater.

4. Use according to claim 3, wherein the compound is ###0002### The organic matter includes sulfonamides, sulfadimethoxine, sulfadiazine and methylene blue.

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