Method for preparing zero-valent iron biochar material by using waste desulfurizer and application thereof

Abstract

This invention provides a method for preparing zero-valent iron biochar material using waste desulfurizing agent and its application. The method includes pretreating crop straw to obtain straw powder. The straw powder, waste desulfurizing agent, and Na₂CO₃ are mixed to obtain a mixed material. The mixed material is placed in a tube furnace and heated under nitrogen atmosphere to reduce the waste desulfurizing agent. The mixed material is removed from the tube furnace, impurities are removed, and zero-valent iron biochar is obtained. Zero-valent iron biochar has a high efficiency in removing organic pollutants. Since it is prepared from crop straw and waste desulfurizing agent in relatively large quantities, it expands the iron source for zero-valent iron biochar material and reduces preparation costs. The preparation method provided by this invention does not rely on high-purity iron salts, and the prepared zero-valent iron biochar has the ability to adsorb and degrade antibiotics, thereby efficiently removing antibiotics from the polluted environment.

Description

Technical Field

[0001] This invention relates to the fields of antibiotic pollution treatment and material preparation technology, and in particular to a method for preparing zero-valent iron biochar material using waste desulfurizing agent and its application. Background Technology

[0002] Zero-valent iron (ZVI) can achieve high antibiotic removal efficiency, but due to van der Waals forces and magnetic forces, ZVI particles tend to aggregate rapidly, leading to a decrease in specific surface area and active sites, making it difficult for ZVI to react with target pollutants. Biochar-supported ZVI is a composite material formed by loading ZVI onto the surface of biochar, combining the high adsorption capacity of biochar with the strong reducing ability of ZVI.

[0003] Waste desulfurizing agent is a solid waste generated during the dry H2S removal process. Its main components are metal sulfides formed after absorbing H2S, and sulfur generated during regeneration. Improper disposal will release toxic gases into the air, and traditional landfill and ocean dumping methods will pollute water and soil.

[0004] Therefore, there is a need for a method to prepare zero-valent iron biochar materials that can quickly remove antibiotics from water at a low cost. Summary of the Invention

[0005] To overcome the problems existing in related technologies, the purpose of this invention is to provide a method for preparing zero-valent iron biochar materials using waste desulfurizing agents and its application, wherein the method can quickly remove antibiotics from water and is low in cost.

[0006] A method for preparing zero-valent iron biochar materials using waste desulfurizing agents includes:

[0007] S1: Pre-treat crop straw to obtain straw powder;

[0008] S2: Mix the straw powder, waste desulfurizer and Na2CO3 to obtain a mixed material;

[0009] S3: The mixed material is placed in a tubular furnace and heated in a nitrogen atmosphere to reduce the waste desulfurizing agent;

[0010] S4: Take out the mixed material from the tubular furnace, remove impurities from the mixed material, and obtain zero-valent iron biochar.

[0011] In a preferred embodiment of the present invention, in step S2, the ratio of straw powder, waste desulfurizing agent and Na2CO3 is 1:0.5:0.75.

[0012] In a preferred embodiment of the present invention, in step S2, after mixing the straw powder, waste desulfurizing agent and Na2CO3, the straw powder, waste desulfurizing agent and Na2CO3 are pulverized using a ball mill for 10 minutes to obtain a mixed material.

[0013] In a preferred embodiment of the present invention, the heating process in step S3 starts from the initial temperature, and the mixed material is heated to 800°C at a rate of 5°C / min and held for 2 hours. During the heating process, nitrogen gas is introduced into the tubular furnace.

[0014] In a preferred embodiment of the present invention, in step S3, under the action of Na2CO3, FeS in the waste desulfurizing agent undergoes a reduction reaction with C in the straw powder to generate zero-valent iron and carbon monoxide.

[0015] In a preferred embodiment of the present invention, in step S3, under the action of Na2CO3, the elemental sulfur in the waste desulfurizing agent reacts with the C in the straw powder to generate Na2S and carbon monoxide.

[0016] In a preferred embodiment of the present invention, in step S3, the iron oxide in the waste desulfurizing agent undergoes a reduction reaction with the C in the straw powder to generate zero-valent iron and carbon dioxide.

[0017] In a preferred embodiment of the present invention, in step S4, deionized water is used to soak and wash the byproduct Na2S adhering to the surface of the iron-carbon material until the acidity or alkalinity of the eluent is neutral; the solid material in the eluent is filtered out, and the solid material is frozen and dried to obtain zero-valent iron biochar.

[0018] In a preferred embodiment of the present invention, in step S1, the crop straw is washed and cut into multiple sections, and the multiple sections of crop straw are placed in an oven and dried at 80°C for 12-24 hours to obtain dried straw; the dried straw is taken out, crushed and sieved to obtain straw powder.

[0019] The present invention also provides the application of the method for preparing zero-valent iron biochar material using waste desulfurizing agent in the removal of antibiotics. Zero-valent iron biochar is prepared using the method for preparing zero-valent iron biochar material using waste desulfurizing agent, and the zero-valent iron biochar is added to a reaction system of multiple antibiotics of the same concentration to remove antibiotics from the antibiotic reaction system.

[0020] The beneficial effects of this invention are as follows:

[0021] This invention provides a method for preparing zero-valent iron biochar material using waste desulfurizing agents. The method includes pretreating crop straw to obtain straw powder. The straw powder, waste desulfurizing agent, and Na₂CO₃ are mixed to obtain a mixed material. The mixed material is placed in a tubular furnace and heated under nitrogen atmosphere to reduce the waste desulfurizing agent. The mixed material is then removed from the tubular furnace, and impurities are removed to obtain zero-valent iron biochar. Zero-valent iron biochar has a high efficiency in removing organic pollutants. Since it is prepared from crop straw and waste desulfurizing agent, the relatively large quantities of these materials expand the iron source for zero-valent iron biochar material and reduce preparation costs. The preparation method provided by this invention does not rely on high-purity iron salts, and the prepared zero-valent iron biochar has the ability to adsorb and degrade antibiotics, thereby efficiently removing antibiotics from water. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method for preparing zero-valent iron biochar material using waste desulfurizing agent according to the present invention;

[0023] Figure 2 The present invention relates to zero-valent iron corn biochar, i.e., C, at different temperatures. C -W D The results of ZVI adsorption of antibiotics are shown in the figure, where (a) is the adsorption capacity of C. C -W D The adsorption capacity of ZVI for TC antibiotics at different temperatures, (b) is C C -W D The adsorption capacity of ZVI for OTC antibiotics at different temperatures, (c) is C C -W D The adsorption capacity of ZVI for SMX antibiotics at different temperatures, (d) is C C -W D The adsorption capacity of ZVI for SMZ antibiotics at different temperatures, (e) is C C -W D The adsorption capacity of ZVI for SZ class antibiotics at different temperatures;

[0024] Figure 3 This is the C of the present invention. C -W D Figure showing the removal rates of antibiotics at different concentrations using ZVI;

[0025] Figure 4 The figures show the results of the antibiotic removal experiment of the present invention, where (a) is a figure showing the antibiotic removal effect of materials prepared by different ratios of waste desulfurizing agent and biochar, and (b) is a figure showing the antibiotic removal effect of rice biochar with different ratios of waste desulfurizing agent.

[0026] Figure 5 This is a time curve of the antibiotic removal rate of zero-valent iron biochar of the present invention;

[0027] Figure 6 This is a diagram of possible transformation pathways of SMX in the system of this invention. Pathway I is hydroxylation, path II is bond cleavage, and path III is oxidation. Detailed Implementation

[0028] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make the invention more thorough and complete, and to fully convey the scope of the invention to those skilled in the art.

[0029] Example 1

[0030] like Figure 1 As shown, this embodiment provides a method for preparing zero-valent iron biochar material using waste desulfurizing agent, including:

[0031] S1: Pre-treat crop straw to obtain straw powder.

[0032] S2: Mix the straw powder, waste desulfurizer and Na2CO3 to obtain a mixed material.

[0033] S3: The mixed material is placed in a tubular furnace and heated in a nitrogen atmosphere to reduce the waste desulfurizing agent.

[0034] S4: Take out the mixed material from the tubular furnace, remove impurities from the mixed material, and obtain zero-valent iron biochar.

[0035] The crop straw used in this invention is corn straw or rice straw, preferably corn straw. In step S2, the ratio of straw powder, waste desulfurizing agent, and Na2CO3 is 1:0.5:0.75. The ratio of straw powder to waste desulfurizing agent can also be 1:0.1, 1:1, and 1:1.5. This embodiment uses a ratio of straw powder to waste desulfurizing agent of 1:0.5 as an example.

[0036] Na2CO3 is used as a reducing agent. After mixing straw powder, waste desulfurizing agent and Na2CO3, the mixture is pulverized in a ball mill for 10 minutes to obtain a mixed material.

[0037] The mixture is placed in a tube furnace, and nitrogen is introduced into the furnace as a protective gas. The initial temperature of the tube furnace can be 100°C, 200°C, or 300°C, which is not limited here. The mixture is heated from the initial temperature to 800°C at a rate of 5°C / min and held for 2 hours.

[0038] In step S4, deionized water is used to soak and wash the byproduct Na2S adhering to the surface of the iron-carbon material until the acidity or alkalinity of the eluent is neutral; the solid material in the eluent is filtered out, and the solid material is frozen and dried to obtain zero-valent iron biochar.

[0039] This embodiment provides a method for preparing zero-valent iron biochar material using waste desulfurizing agent, comprising pretreating crop straw to obtain straw powder. The straw powder, waste desulfurizing agent, and Na2CO3 are mixed to obtain a mixed material. The mixed material is placed in a tubular furnace and heated under nitrogen atmosphere to reduce the waste desulfurizing agent. The mixed material is removed from the tubular furnace, impurities are removed, and zero-valent iron biochar is obtained. Zero-valent iron biochar has a high efficiency in removing organic pollutants. Since it is prepared from crop straw and waste desulfurizing agent, the large quantities of these materials expand the iron source for zero-valent iron biochar material and reduce preparation costs. The preparation method provided by this invention does not rely on high-purity iron salts, and the prepared zero-valent iron biochar has the ability to adsorb and degrade antibiotics, thereby efficiently removing antibiotics from water.

[0040] Example 2

[0041] This embodiment describes the differences from Embodiment 1. This embodiment provides a method for preparing zero-valent iron biochar material using waste desulfurizing agent, comprising:

[0042] S1: Pre-treat crop straw to obtain straw powder;

[0043] S2: Mix the straw powder, waste desulfurizer and Na2CO3 to obtain a mixed material;

[0044] S3: The mixed material is placed in a tubular furnace and heated in a nitrogen atmosphere to reduce the waste desulfurizing agent;

[0045] S4: Take out the mixed material from the tubular furnace, remove impurities from the mixed material, and obtain zero-valent iron biochar.

[0046] In step S3, under the action of Na2CO3, FeS in the waste desulfurizing agent reacts with C in the straw powder to produce zero-valent iron and carbon monoxide. The chemical reaction equation is as follows:

[0047] FeS + 2C + Na₂CO₃ → Fe 0 +3CO + Na2S;

[0048] In step S3, under the action of Na2CO3, the elemental sulfur in the waste desulfurizing agent reacts with the carbon in the straw powder to produce Na2S and carbon monoxide. The chemical reaction equation is as follows:

[0049] S + 2C + Na₂CO₃ → 3CO + Na₂S;

[0050] In step S3, the iron oxides in the waste desulfurizing agent react with the carbon in the straw powder to produce zero-valent iron and carbon dioxide. The chemical reaction equation is as follows:

[0051]

[0052] During the carbothermic reduction reaction, biochar and Na2CO3 first react with FeS and elemental S formed on the surface of the waste desulfurizing agent due to the absorption of H2S gas. The generated CO gas then acts as a reducing agent to further reduce the raw materials. After the surface impurities are reduced, the iron oxide desulfurizing agent that was previously encapsulated is exposed, and the iron oxide compounds in the iron oxide desulfurizing agent continue to be reacted by the reducing agent. After the reaction is complete, the iron-carbon material is removed from the tubular furnace, and the byproducts on the surface of the iron-carbon material are removed to obtain zero-valent iron biochar.

[0053] In step S1, the crop straw is washed and cut into multiple sections. The multiple sections of crop straw are placed in an oven and dried at 80℃ for 12-24 hours to obtain dried straw. The dried straw is then taken out, crushed and sieved to obtain straw powder.

[0054] In this embodiment, corn stalks are used as crop straw to prepare zero-valent iron corn biochar (C) through steps S1-S4. C -W D Take ZVI as an example. Figure 2 The different temperatures of C in this invention C -W D The results of ZVI adsorption of antibiotics are shown in the figure below. Figure 2 As shown in (a)-(e), C C -W D The removal efficiency of ZVI for TC, OTC and SMZ antibiotics did not differ significantly at different temperatures. Among them, SMX and SZ reached their maximum adsorption capacity earlier at 25℃ for 48 hours compared to other temperatures, but desorption occurred at 72 hours.

[0055] Depend on Figure 3 It can be seen that as the initial concentration of antibiotics increases, CC -W D ZVI showed a decreasing removal rate for all five antibiotics, consistent with the adsorption site saturation effect. The removal rate for tetracycline antibiotics, such as TC and OTC, only began to decrease when the dosage concentration was increased to 20 mg / L, demonstrating that C... C -W D ZVI exhibits extremely high removal efficiency against tetracycline antibiotics. As antibiotic concentration increases, C... C -W D The adsorption capacity of ZVI for antibiotics gradually increases, reaching its maximum at an antibiotic dosage of 20 mg / L, specifically TC: 37.43 mg / g, OTC: 34.56 mg / g, SMX: 6.58 mg / g, SMZ: 18.58 mg / g, and SZ: 7.67 mg / g.

[0056] In this embodiment, the mixed material is placed in a tube furnace and heated to 800°C at a rate of 5°C / min, and maintained for 2 hours. The heating temperature change rate is constant in this embodiment, allowing for uniform heating of the mixed material and ensuring that the FeS in the waste desulfurizing agent is fully reduced to zero-valent iron by the C in the straw powder. Simultaneously, the elemental sulfur in the waste desulfurizing agent reacts with the C in the straw powder to generate Na₂S and carbon monoxide. The carbon monoxide gas acts as a reducing agent, further reducing the raw materials and exposing the iron oxides in the iron oxide desulfurizing agent, thereby increasing the yield of zero-valent iron.

[0057] Example 3

[0058] This embodiment discloses the application of a method for preparing zero-valent iron biochar material using waste desulfurizing agent in antibiotic removal. The method for preparing zero-valent iron biochar material using waste desulfurizing agent is the method in Example 1 or Example 2. Zero-valent iron biochar is prepared using the method described above. The zero-valent iron biochar is then added to a reaction system containing multiple antibiotics of the same concentration to remove antibiotics from the reaction system. The antibiotic concentration in the reaction system can be 1 mg / L or other concentrations; this is not limited here. This embodiment uses an antibiotic concentration of 1 mg / L as an example.

[0059] The antibiotic measurement method includes pretreatment: the supernatant is centrifuged at 10000 r / min and 25℃ for 5 min, then vortexed with Na2EDTA-Mcllvaine buffer at a 1:1 ratio, filtered through a membrane, and the supernatant is passed through an activated CNW Poly-Sery HLB Pro SPE column (activation conditions: 5 mL methanol, 5 mL ultrapure water) at a flow rate of 2 mL / min. Elution is performed with 4 mL methanol, and the eluent is thoroughly mixed using a vortex mixer and then filtered through a 0.22 μm filter membrane. The eluent is stored in a brown sample vial and kept at 4℃.

[0060] The analytical methods for antibiotics included the analysis of TC, OTC, SMX, SMZ, and SZ using an Agilent 1920 HPLC-6470B mass spectrometer (UPLC-MS / MS). TC represents tetracycline, OTC represents oxytetracycline, SMX represents sulfamethoxazole, SMZ represents compound sulfamethoxazole, and SZ represents sulfamethoxazole. TC and OTC are tetracycline antibiotics, while SMX, SMZ, and SZ are sulfonamide antibiotics. Chromatographic conditions: Agilent ZORBAX Eclipse Plus C18 column (2.1 mm × 50 mm, 1.8-Micron), column temperature 30 °C, mobile phase composition acetonitrile and 0.1% formic acid in water, mobile phase flow rate 0.3 mL / min, injection volume 2 μL. The elution sequence of the mobile phase is shown in Table 1. Mass spectrometry analysis conditions: electrospray ionization (ESI), positive ion mode, capillary voltage 3.5 kV, desolvation gas flow rate 300 L / min, using N2 as the desolvation gas. Sheath gas was N2, with a flow rate of 11 L / min and a temperature of 250 °C. In mass spectrometry, sheath gas is an important auxiliary gas, mainly used for nebulization, desolvation, and ion focusing. The nozzle voltage was 500 V, and the nebulizing gas pressure was 45 psi. Multiple reaction monitoring (MRM) mode was used for detection, and the mass spectrometry parameters for MRM mode are shown in Table 2. Different peak areas were obtained through analysis, and the antibiotic concentration in the sample was calculated based on the peak areas obtained from the standard curve.

[0061] Table 1. Mobile Phase Gradient Elution Program

[0062]

[0063] The antibiotic removal rate is calculated using the following formula:

[0064]

[0065] Where η is the removal rate of antibiotics (%), C0 is the concentration of antibiotics in CK (mg / L), and C t This represents the residual concentration of the antibiotic in the reaction system (mg / L).

[0066] Table 2 Mass spectrometry parameters for multiple reaction monitoring (MRM) scanning modes

[0067]

[0068] This embodiment utilizes waste desulfurizing agent to prepare zero-valent iron biochar. Crop straw is washed and cut into multiple sections, which are then placed in an oven and dried at 80°C for 12-24 hours. The dried straw is then removed, crushed, and sieved. Different proportions of straw, waste desulfurizing agent, and Na2CO3 reducing agent are mixed and pulverized using a ball mill for 10 minutes. The mixture is then placed in a tube furnace, using nitrogen as a protective gas, and heated to 800°C at a rate of 5°C / min and maintained for 2 hours. During the carbothermic reduction reaction, the biochar and Na2CO3 first react with FeS and elemental S formed on the surface of the waste desulfurizing agent due to the absorption of H2S gas. The generated CO gas acts as a reducing gas, further reducing the raw materials. After the surface impurities are reduced, the encapsulated iron oxide desulfurizing agent is exposed, and the iron oxide compounds in the iron oxide desulfurizing agent continue to be reacted by the reducing agent. After the reaction is complete, the iron-carbon material is removed from the tubular furnace. The byproduct Na₂S adhering to the surface of the iron-carbon material is soaked and washed with deionized water until the eluent is neutral. The solid material in the eluent is then filtered out, frozen, and dried to obtain zero-valent iron biochar. Alternatively, the biochar source can be changed from corn to rice, i.e., rice straw is used to reduce waste desulfurizing agent to obtain zero-valent iron rice biochar.

[0069] This embodiment also included performance optimization experiments on iron-carbon composite materials. Different reaction conditions were set to prepare iron-carbon based composite materials, with the following parameters:

[0070] The mixing ratios of waste desulfurizing agent were: C:waste desulfurizing agent = 1:0.1, 1:0.5, 1:1, and 1:1.5. Antibiotic degradation experiments were conducted using various prepared composite materials to compare their antibiotic degradation capabilities and determine the optimal preparation parameters. The antibiotic degradation experiments were as follows: A certain amount of the target composite material was added to the reaction system, along with different antibiotics, to achieve a concentration of 1 mg / L for each antibiotic. After sealing, the system was placed in a shaker at 30℃ and 160 r / min. Samples were taken at specific time points to measure the residual antibiotic concentration. Each system was replicated in duplicate, with a blank control (without adsorbent) included. The material dosage was 0.1 g, and the reaction time was 2 h.

[0071] The removal results of antibiotics by an iron-carbon composite material prepared from waste desulfurizing agent and biochar via carbothermal reduction are as follows: Figure 4 (a) and Figure 4 As shown in (b), by Figure 4 (a) and Figure 4(b) It can be seen that zero-valent iron biochar prepared by mixing different biomass with different proportions of waste desulfurizing agent has a similar trend in antibiotic removal effect. D =1:0.1 (m / m) and C:W D The effect is best when the ratio is 1:0.5 (m / m), where CC:W D At a C:W ratio of 1:0.5 (m / m), the removal rates of the five antibiotics were TC: 99.4%, OTC: 99.7%, SMX: 98.3%, SMZ: 99.3%, and SZ: 99.7%. D =1:1 (m / m) and C:W D When the ratio is 1:1.5 (m / m), it affects the removal rate of SMX and SMZ. The removal effect on antibiotics was basically not tested. This may be because the high proportion of waste desulfurizer causes ZVI to agglomerate or cover the surface, thereby reducing the effective adsorption sites.

[0072] This embodiment utilizes various prepared composite materials to conduct antibiotic degradation experiments, comparing the degradation capabilities of different composite materials to determine the optimal preparation parameters. Based on the above experimental results, this embodiment selects zero-valent iron corn biochar (C0.05) prepared with a ratio of corn straw to waste desulfurizing agent of 1:0.5 (m / m). C -W D ZVI was used as the subject of subsequent experiments.

[0073] Example 4

[0074] This embodiment discloses the application of a method for preparing zero-valent iron biochar material using waste desulfurizing agent in antibiotic removal. The method for preparing zero-valent iron biochar material using waste desulfurizing agent is the method in Example 1 or Example 2. Zero-valent iron biochar is prepared using the method described above. The zero-valent iron biochar is then added to a reaction system containing multiple antibiotics of the same concentration to remove antibiotics from the reaction system. The antibiotic concentration in the reaction system can be 1 mg / L or other concentrations; this is not limited here. This embodiment uses an antibiotic concentration of 1 mg / L as an example.

[0075] This embodiment uses the antibiotic measurement and analysis methods described in Example 3. C -W D The time curve of antibiotic removal rate of ZVI (zero valent iron) corn biochar is as follows: Figure 5 As shown, C C -W DThe removal efficiency of ZVI for the five antibiotics generally increased over time, with a significant effect on tetracyclines, reaching over 95% at 0.5 hours and over 98% at 1 hour. The removal rates for sulfonamides rapidly increased within 12 hours to 66.9% for SMX, 95.2% for SMZ, and 73.3% for SZ, before slowing down after 12 hours. The highest removal rates for TC, OTC, SMX, SMZ, and SZ were 99.7%, 99.7%, 82.2%, 97.4%, and 85.7%, respectively, with no significant desorption observed within 72 hours.

[0076] Depend on Figure 5 It can be seen that C C -W D ZVI exhibits high efficiency in removing TC and OTC antibiotics, achieving nearly 100% removal rates within 2 hours of adsorption. In contrast, while the removal rates and efficiencies of SMX, SMZ, and SZ antibiotics are lower than those of TC and OTC antibiotics, they still maintain relatively high levels. For example, the removal time curve for SMZ antibiotics converges around 12 hours, i.e., C... C -W D ZVI removal rate for SMZ antibiotics reached a maximum of 95% at approximately 12 hours and remained constant over time. The removal rate for SZ antibiotics was higher than that for SMX antibiotics but lower than that for SMZ antibiotics. Within 0-12 hours, C... C -W D ZVI removal rate of SZ class antibiotics increased rapidly and fluctuated within 0-5 hours. At 12 hours, the removal rate of SZ class antibiotics was greater than 70%, and increased slowly from 12 to 72 hours, finally reaching 85.7% at 72 hours. Within 0-12 hours, C... C -W D ZVI showed a similar pattern in the removal rates of SMX and SZ antibiotics, namely a rapid increase followed by fluctuations. At 12 h, the removal rate of SMX antibiotics was greater than 65%, then decreased and then increased again between 12 and 72 h, finally reaching 82.2% at 72 h.

[0077] This embodiment draws C. C -W D The removal rate curves of ZVI for five classes of antibiotics (TC, OTC, SMX, SMZ, and SZ) are shown. The x-axis represents adsorption time in hours (h), and the y-axis represents removal rate in percentage (%). C -W D ZVI exhibits high removal efficacy and efficiency for both TC and OTC antibiotics; removal efficacy is measured by the removal rate. C -W DZVI showed higher removal efficiency for SZ class antibiotics than for SMX class antibiotics, but lower efficiency than for SMZ class antibiotics. The removal rates of TC and OTC antibiotics showed similar curves with adsorption time, as did the removal rates of SMX, SMZ, and SZ class antibiotics.

[0078] Example 5

[0079] This embodiment discloses the application of a method for preparing zero-valent iron biochar material using waste desulfurizing agent in antibiotic removal. The method for preparing zero-valent iron biochar material using waste desulfurizing agent is the method in Example 1 or Example 2. Zero-valent iron biochar is prepared using the method described above. The zero-valent iron biochar is then added to a reaction system containing multiple antibiotics of the same concentration to remove antibiotics from the reaction system. The antibiotic concentration in the reaction system can be 1 mg / L or other concentrations; this is not limited here. This embodiment uses an antibiotic concentration of 1 mg / L as an example.

[0080] This embodiment uses the antibiotic measurement method and antibiotic analysis method from Example 3. This embodiment will use C... C -W D ZVI (zero-valent iron) corn biochar was used to identify the degradation products of SMX, analyze the intermediate products that may exist during the degradation process, and deduce the degradation pathway. A total of 9 products were detected during the SMX degradation process, and their corresponding mass-to-charge ratio (m / z), molecular weight, molecular formula, and chemical structure are listed in Table 3.

[0081] Table 3 in C C -W D Table of SMX degradation products in the ZVI system

[0082]

[0083] This embodiment provides nine products generated during the degradation of SMX, along with their corresponding mass-to-charge ratios, molecular weights, molecular formulas, and chemical structures. All nine products contain benzene rings, and compared to SMX, they exhibit lower toxicity.

[0084] Example 6

[0085] This embodiment discloses the application of a method for preparing zero-valent iron biochar material using waste desulfurizing agent in antibiotic removal. The method for preparing zero-valent iron biochar material using waste desulfurizing agent is the method in Example 1 or Example 2. Zero-valent iron biochar is prepared using the method described above. The zero-valent iron biochar is then added to a reaction system containing multiple antibiotics of the same concentration to remove antibiotics from the reaction system. The antibiotic concentration in the reaction system can be 1 mg / L or other concentrations; this is not limited here. This embodiment uses an antibiotic concentration of 1 mg / L as an example.

[0086] This embodiment uses the antibiotic measurement method and antibiotic analysis method from Example 3. This embodiment derives C... C -W D The degradation pathway of SMX by ZVI (zero-valent iron) corn biochar, combined with the main degradation products and the microscopic changes before and after the above reaction, suggests that C C -W D The main pathways by which ZVI degrades SMX are as follows: Figure 6 As shown, there are three pathways, including hydroxylation, bond cleavage (zero-valent iron reduction synergistic), and oxidation.

[0087] In degradation pathway I, ZVI reacts with activated molecular oxygen in the system via two-electron transfer or sequential single-electron transfer to generate ·OH, which attacks SMX to form product m / z = 278, consistent with typical phenolic hydroxyl addition characteristics. The continued attack of ·OH causes the sulfonamide group in product m / z = 278 to cleave (or possibly be reduced and broken by electron donors from ZVI), forming a possible product m / z = 201 (not detected), which is ultimately oxidized to m / z = 123.

[0088] In degradation pathway II, ·OH oxidizes the amino group of SMX to a nitro group, producing a product with m / z = 284. The free radical may directly attack the electron-donating group in the SMX molecule, causing it to oxidize. Under the combined action of ·OH and ZVI, the SN bond is further broken, forming a product with m / z = 158; this product is finally oxidized to m / z = 110.

[0089] In degradation pathway III, the ·OH generated from activated molecular oxygen hydroxylates SMX to produce product m / z = 270. Subsequently, the electron donation from ZVI and the ·OH radical together break the SN bond in the m / z = 270 molecule, causing it to break and form m / z = 190. Under the further oxidation by the radical, m / z = 190 undergoes a CS bond breaking reaction caused by radical attack on the C site and a HO· addition reaction, thus transforming into m / z = 142 and m / z = 99.

[0090] In summary, this embodiment has experimentally verified C. C-W D The main mechanisms by which the ZVI system degrades SMX include hydroxylation, bond breaking (synergistic reduction of zero-valent iron), and oxidation. At the same time, the response values ​​of SMX and its small molecule products with reaction time were detected. The response value of small molecule products decreased with time, proving that SMX continued to decompose and its toxicity decreased over time.

[0091] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0092] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. The application of zero-valent iron biochar material prepared from waste desulfurizing agent in the removal of antibiotics, characterized in that, include: S1: Pre-treat crop straw to obtain straw powder; S2: Mix the straw powder, waste desulfurizer and Na2CO3 to obtain a mixed material; S3: The mixed material is placed in a tubular furnace and heated in a nitrogen atmosphere to reduce the waste desulfurizing agent; S4: Take out the mixed material from the tubular furnace, remove impurities from the mixed material, and obtain zero-valent iron biochar; In step S3, under the action of Na2CO3, FeS in the waste desulfurizing agent reacts with C in the straw powder to produce zero-valent iron and carbon monoxide. In step S3, under the action of Na2CO3, the elemental sulfur in the waste desulfurizing agent reacts with the C in the straw powder to produce Na2S and carbon monoxide. In step S3, the iron oxide in the waste desulfurizing agent reacts with the C in the straw powder to produce zero-valent iron and carbon dioxide; When using, the zero-valent iron biochar is added to a reaction system of multiple antibiotics of the same concentration to remove the antibiotics from the reaction system.

2. The application of the zero-valent iron biochar material prepared from waste desulfurizing agent according to claim 1 in the removal of antibiotics, characterized in that, In step S2, the ratio of straw powder, waste desulfurizing agent and Na2CO3 is 1:0.5:0.

75.

3. The application of the zero-valent iron biochar material prepared from waste desulfurizing agent according to claim 1 in the removal of antibiotics, characterized in that, In step S2, the straw powder, waste desulfurizing agent and Na2CO3 are mixed and then pulverized using a ball mill for 10 minutes to obtain a mixed material.

4. The application of the zero-valent iron biochar material prepared from waste desulfurizing agent according to claim 1 in the removal of antibiotics, characterized in that, The heating process in step S3 starts from the initial temperature, and the mixed material is heated to 800°C at a rate of 5°C / min and held for 2 hours. During the heating process, nitrogen gas is introduced into the tubular furnace.

5. The application of the zero-valent iron biochar material prepared from waste desulfurizing agent according to claim 1 in the removal of antibiotics, characterized in that, In step S4, deionized water is used to soak and wash the byproduct Na2S adhering to the surface of the iron-carbon material until the acidity or alkalinity of the eluent is neutral; the solid material in the eluent is filtered out, and the solid material is frozen and dried to obtain zero-valent iron biochar.

6. The application of the zero-valent iron biochar material prepared from waste desulfurizing agent according to claim 1 in the removal of antibiotics, characterized in that, In step S1, the crop straw is washed and cut into multiple sections. The multiple sections of crop straw are placed in an oven and dried at 80℃ for 12-24 hours to obtain dried straw. The dried straw is then taken out, crushed and sieved to obtain straw powder.

Images