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

Abstract

The invention provides a method for preparing a zero-valent iron biochar material by using a waste desulfurizer and application of the zero-valent iron biochar material, and the method comprises the following steps: pretreating crop straws to obtain straw powder; mixing the straw powder, the waste desulfurizer and Na2CO3 to obtain a mixed material; and putting the mixed material into a tubular furnace, and heating the mixed material in a nitrogen environment so as to reduce the waste desulfurizer. The mixed material is taken out of the tubular furnace, impurities in the mixed material are removed, and the zero-valent iron biochar is obtained. The zero-valent iron biochar has the capacity of efficiently removing organic pollutants, the zero-valent iron biochar is prepared from crop straw and a waste desulfurizer, the amount of the crop straw and the amount of the waste desulfurizer are large, the iron element source of the zero-valent iron biochar material is expanded, and the preparation cost is reduced. The preparation method provided by the invention does not need to depend on high-purity ferric salt, and the prepared zero-valent iron biochar has the capability of degrading the antibiotics after adsorption, so that the antibiotics in the polluted environment are efficiently removed.

Description

Technical Field

[0001] The present invention relates to the technical fields of antibiotic pollution treatment and material preparation, and particularly to a method for preparing zero-valent iron biochar material using waste desulfurizer and its application. Background Art

[0002] Zero-valent iron, i.e., ZVI, can achieve high antibiotic removal efficiency. However, due to the action of van der Waals and magnetic forces, ZVI particles tend to rapidly aggregate, resulting in a decrease in specific surface area and a reduction in active sites, making it difficult for ZVI to react with target pollutants. Biochar-supported zero-valent iron is a composite material formed by loading ZVI on the surface of biochar, which combines the high adsorption of biochar and the strong reduction ability of ZVI.

[0003] Waste desulfurizer is a solid waste of ineffective desulfurizer generated in the process of dry desulfurization of H2S. The main components of waste desulfurizer are metal sulfides generated after absorbing H2S and sulfur generated during the regeneration process. Random stacking will emit toxic gases into the air. Using traditional landfill and sea dumping methods to treat waste desulfurizer will cause pollution to water and soil.

[0004] Therefore, a method for preparing zero-valent iron biochar material that can rapidly remove antibiotics in water and has a low cost is needed. Summary of the Invention

[0005] To overcome the problems existing in the related technologies, the purpose of the present invention is to provide a method for preparing zero-valent iron biochar material using waste desulfurizer and its application, wherein the method can rapidly remove antibiotics in water and has a low cost.

[0006] A method for preparing zero-valent iron biochar material using waste desulfurizer includes:

[0007] S1: Pretreat crop straw to obtain straw powder;

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

[0009] S3: Put the mixed material into a tube furnace and heat the mixed material in a nitrogen environment to reduce the waste desulfurizer;

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

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

[0012] In a preferred technical solution of the present invention, in step S2, after mixing the straw powder, waste desulfurizer, and Na2CO3, use a ball mill to crush the straw powder, waste desulfurizer, and Na2CO3 for 10 min to obtain a mixed material.

[0013] In a preferred technical solution 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 maintained for 2 h. During the heating process, nitrogen is introduced into the tubular furnace.

[0014] In a preferred technical solution of the present invention, in step S3, under the action of Na2CO3, FeS in the waste desulfurizer reacts with C in the straw powder to generate zero-valent iron and carbon monoxide.

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

[0016] In a preferred technical solution of the present invention, in step S3, iron oxides in the waste desulfurizer react with C in the straw powder to generate zero-valent iron and carbon dioxide.

[0017] In a preferred technical solution of the present invention, in step S4, deionized water is used to soak and wash the by-product Na2S attached to the surface of the iron-carbon material until the acid-base property of the eluate is neutral; the solid material in the eluate is filtered out, and the solid material is frozen and dried to obtain zero-valent iron biochar.

[0018] In a preferred technical solution of the present invention, in step S1, the crop straw is washed and cut into multiple segments, and the multiple segments of crop straw are placed in an oven and dried at 80 °C for 12 - 24 h to obtain dried straw; the dried straw is taken out, and the dried straw is 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 desulfurizer in removing antibiotics. Zero-valent iron biochar is prepared by using the method for preparing zero-valent iron biochar material using waste desulfurizer, and the zero-valent iron biochar is added into reaction systems of various antibiotics with the same concentration respectively to remove the antibiotics in the antibiotic reaction systems.

[0020] The beneficial effects of the present invention are:

[0021] A method for preparing zero-valent iron biochar material using waste desulfurizer provided by the present invention includes pretreating crop straws to obtain straw powders. Mixing the straw powders, waste desulfurizer, and Na2CO3 to obtain a mixed material. Placing the mixed material into a tube furnace and heating the mixed material in a nitrogen environment to reduce the waste desulfurizer. Taking out the mixed material from the tube furnace and removing impurities in the mixed material to obtain zero-valent iron biochar. The zero-valent iron biochar has the ability to efficiently remove organic pollutants. The zero-valent iron biochar is prepared from crop straws and waste desulfurizer, and the amounts of crop straws and waste desulfurizer are large, which expands the iron element source of the zero-valent iron biochar material and reduces the preparation cost. The preparation method provided by the present invention does not need to rely on high-purity iron salts, and the prepared zero-valent iron biochar has the ability to adsorb and degrade antibiotics, so as to efficiently remove antibiotics in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the method for preparing zero-valent iron biochar material using waste desulfurizer of the present invention;

[0023] Figure 2 is the result graph of the adsorption amount of zero-valent iron corn biochar, i.e., C C -W D ZVI against antibiotics, where (a) is the adsorption amount of C C -W D ZVI on TC antibiotics at different temperatures, (b) is the adsorption amount of C C -W D ZVI on OTC antibiotics at different temperatures, (c) is the adsorption amount of C C -W D ZVI on SMX antibiotics at different temperatures, (d) is the adsorption amount of C C -W D ZVI on SMZ antibiotics at different temperatures, (e) is the adsorption amount of C C -W D ZVI on SZ antibiotics at different temperatures;

[0024] Figure 3 is the result graph of the removal rate of C C -W D ZVI on antibiotics with different concentrations;

[0025] Figure 4 is the experimental result graph of the removal of antibiotics by the present invention, where (a) is the effect graph of the removal of antibiotics by the materials prepared with different ratios of waste desulfurizer and biochar, and (b) is the effect graph of the removal of antibiotics by rice biochar with different doping ratios of waste desulfurizer;

[0026] Figure 5 It is the time curve graph of the removal rate of antibiotics by the zero-valent iron biochar of the present invention;

[0027] Figure 6 It is the possible transformation pathway graph of SMX in the system of the present invention. Pathway I is hydroxylation, Pathway II is bond cleavage, and Pathway III is oxidation. Detailed implementation manners

[0028] The preferred implementation manners of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred implementation manners of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the implementation manners set forth herein. On the contrary, these implementation manners are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0029] Example 1

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

[0031] S1: Pretreat the crop straw to obtain straw powder.

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

[0033] S3: Put the mixed material into a tube furnace and heat the mixed material in a nitrogen environment to reduce the waste desulfurizer.

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

[0035] The crop straw of the present invention is corn straw or rice straw, preferably corn straw. In step S2, the ratio of straw powder, waste desulfurizer, and Na2CO3 is 1:0.5:0.75. The ratio of straw powder to waste desulfurizer can also be 1:0.1, 1:1, and 1:1.5. This example takes the ratio of straw powder to waste desulfurizer as 1:0.5.

[0036] Na2CO3 is a reducing agent. After mixing the straw powder, waste desulfurizer, and Na2CO3, use a ball mill to crush the straw powder, waste desulfurizer, and Na2CO3 for 10 min to obtain a mixed material.

[0037] Put the mixed material into a tube furnace, use nitrogen as the protective gas, and introduce nitrogen into the tube furnace. The initial temperature of the tube furnace can be 100 °C, or it can be 200 or 300 °C, which is not limited here. Heat the mixed material from the initial temperature to 800 °C at a rate of 5 °C / min and hold for 2 h.

[0038] In the step S4, soak and wash the by-product Na2S attached to the surface of the iron-carbon material with deionized water until the acidity and alkalinity of the eluate are neutral; filter out the solid material in the eluate, freeze and dry the solid material to obtain zero-valent iron biochar.

[0039] A method for preparing zero-valent iron biochar material using waste desulfurizer provided in this embodiment includes pretreating crop straw to obtain straw powder. Mix the straw powder, waste desulfurizer, and Na2CO3 to obtain a mixed material. Put the mixed material into a tube furnace and heat the mixed material in a nitrogen environment to reduce the waste desulfurizer. Take out the mixed material from the tube furnace, remove the impurities in the mixed material to obtain zero-valent iron biochar. Zero-valent iron biochar has the ability to efficiently remove organic pollutants. Zero-valent iron biochar is prepared from crop straw and waste desulfurizer. The amounts of crop straw and waste desulfurizer are large, which expands the source of iron elements for zero-valent iron biochar materials and reduces the preparation cost. The preparation method provided by the present invention does not need to rely on high-purity iron salts. The prepared zero-valent iron biochar has the ability to adsorb and degrade antibiotics, so as to efficiently remove antibiotics in water.

[0040] Example 2

[0041] Based on Example 1, this example describes the differences from Example 1. This example provides a method for preparing zero-valent iron biochar material using waste desulfurizer, including:

[0042] S1: Pretreat crop straw to obtain straw powder;

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

[0044] S3: Put the mixed material into a tube furnace and heat the mixed material in a nitrogen environment to reduce the waste desulfurizer;

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

[0046] In step S3, under the action of Na2CO3, FeS in the waste desulfurizer reacts with C in the straw powder to generate 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 desulfurizer reacts with C in the straw powder to generate Na2S and carbon monoxide. The chemical reaction equation is as follows:

[0049] S + 2C + Na2CO3 → 3CO + Na2S;

[0050] In step S3, the iron oxide in the waste desulfurizer reacts with C in the straw powder to generate zero-valent iron and carbon dioxide. The chemical reaction equation is as follows:

[0051]

[0052] During the carbothermal reduction reaction process, biochar and Na2CO3 will first react with FeS and elemental sulfur formed on the surface of the waste desulfurizer due to the absorption of H2S gas. The generated CO gas will continue to act as a reducing agent to reduce the raw materials. After the surface impurities are reduced, the encapsulated iron oxide desulfurizer will be exposed, and the iron oxides in the iron oxide desulfurizer will continue to react with the reducing agent. After the reaction, the iron-carbon material is taken out of the tubular furnace, and the by-products 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 °C for 12 - 24 h to obtain the dried straw; the dried straw is taken out, pulverized and sieved to obtain straw powder.

[0054] In this embodiment, the crop straw is corn straw, and zero-valent iron corn biochar, namely C C -W D ZVI for example. Figure 2 is the result graph of the adsorption amount of C C -W D ZVI against antibiotics at different temperatures, as shown in Figure 2 (a)-(e) in. C C -W D The differences in the removal effects of ZVI on TC, OTC, and SMZ antibiotics at different temperatures are not obvious. Among them, SMX and SZ can reach the highest adsorption amount point earlier at 25 °C for 48 h compared with other temperatures, but desorption will occur at 72 h.

[0055] From Figure 3 it can be seen that as the initial concentration of antibiotics increases, CC -W D The removal rates of ZVI for the five antibiotics all showed a downward trend, which was in line with the adsorption site saturation effect. Among them, the removal rates of tetracycline antibiotics such as TC and OTC began to decline when the dosing concentration increased to 20 mg / L, proving that C C -W D ZVI has extremely high removal effects on tetracycline antibiotics. With the increase of antibiotic concentration, C C -W D The adsorption amounts of ZVI for antibiotics gradually increased and reached the maximum when the antibiotic dosing amount was 20 mg / L, which were 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, respectively.

[0056] In this embodiment, the mixed material was placed in a tube furnace, and the mixed material was heated to 800 °C at a rate of 5 °C / min and maintained for 2 h. The change rate of the heating temperature in this embodiment was fixed, which could uniformly heat the mixed material and make the FeS in the waste desulfurizer be fully reduced to zero-valent iron by C in the straw powder. At the same time, the elemental sulfur in the waste desulfurizer reacted with C in the straw powder to generate Na2S and carbon monoxide. The carbon monoxide gas would continue to act as a reducing agent to reduce the raw materials, exposing the iron oxides in the iron oxide desulfurizer, thereby increasing the yield of zero-valent iron.

[0057] Example 3

[0058] This embodiment discloses the application of the method for preparing zero-valent iron biochar materials using waste desulfurizer in the removal of antibiotics. The method for preparing zero-valent iron biochar materials using waste desulfurizer is the method in Example 1 or Example 2. Zero-valent iron biochar was prepared using the method for preparing zero-valent iron biochar materials using waste desulfurizer, and the zero-valent iron biochar was respectively added into reaction systems of various antibiotics with the same concentration to remove the antibiotics in the antibiotic reaction systems. The antibiotic concentration in the antibiotic reaction system can be 1 mg / L or other concentrations, which is not limited here. This embodiment takes the antibiotic concentration of 1 mg / L as an example.

[0059] The antibiotic measurement method includes pretreatment: Take the supernatant, centrifuge it at 10,000 r / min and 25 °C for 5 min, then vortex and mix it with Na2EDTA-Mcllvaine buffer in a ratio of 1:1, filter through a membrane. The supernatant passes through an activated CNW Poly-Sery HLB Pro SPE column (activation conditions: 5 mL of methanol, 5 mL of ultrapure water) at a flow rate of 2 mL / min, elute with 4 mL of methanol. The eluate is thoroughly mixed using a vortex mixer and then passed through a 0.22-μm filter membrane, and stored in a brown injection vial and placed in an environment at 4 °C.

[0060] The analytical method for antibiotics includes using an Agilent 1920 liquid chromatography-6470B mass spectrometry (UPLC-MS / MS) to analyze TC, OTC, SMX, SMZ, and SZ. TC represents tetracycline, OTC represents oxytetracycline, SMX represents sulfamethoxazole, SMZ represents compound sulfamethoxazole, and SZ represents sulfamethizole. Both TC and OTC are tetracycline antibiotics, and SMX, SMZ, and SZ are sulfonamide antibiotics. Chromatographic analysis conditions: Agilent ZORBAX Eclipse Plus C18 chromatographic column (2.1 mm × 50 mm, 1.8-Micron), column temperature 30 °C, mobile phase components are acetonitrile and 0.1% formic acid in water, mobile phase flow rate is 0.3 mL / min, injection volume is 2 μL. The mobile phase elution sequence is shown in Table 1. Mass spectrometry analysis conditions: electrospray ionization source (ESI), positive ion mode, capillary voltage is 3.5 kV, desolvation gas flow rate is 300 L / min, desolvation gas uses N2. Sheath gas uses N2, sheath gas flow rate is 11 L / min, sheath gas temperature is 250 °C. In mass spectrometry analysis, sheath gas is an important auxiliary gas, mainly used for atomization, desolvation, and ion focusing. Nozzle voltage is 500 V, atomizing gas pressure is 45 psi. Detection is carried out using the multiple reaction monitoring (MRM) mode, and the mass spectrometry parameters of the multiple reaction monitoring mode are shown in Table 2. Different peak areas are obtained through analysis, and the antibiotic concentration in the sample is calculated based on the peak areas obtained from the standard curve.

[0061] Table 1 Mobile phase gradient elution program table

[0062]

[0063] The removal rate of antibiotics is calculated according to the following formula:

[0064]

[0065] Among them, η is the removal rate of antibiotics (%), C0 is the concentration of antibiotics in CK (mg / L), C t is the residual concentration of antibiotics in the reaction system (mg / L).

[0066] Table 2 Mass spectrometry parameters of multiple reaction monitoring scan mode

[0067]

[0068] In this example, zero-valent iron biochar was prepared using waste desulfurizer. The crop straw was washed and cut into multiple segments, and the multiple segments of crop straw were placed in an oven and dried at 80 °C for 12 - 24 h. The dried straw was taken out, crushed and sieved. Different proportions of straw, waste desulfurizer and Na2CO3 reducing agent were mixed, pulverized by a ball mill for 10 min and then put into a tube furnace. Nitrogen was used as the protective gas, and the temperature was raised to 800 °C at a rate of 5 °C / min and maintained for 2 h. During the carbothermal reduction reaction, biomass carbon and Na2CO3 would first react with FeS and elemental sulfur formed on the surface of the waste desulfurizer due to the absorption of H2S gas. The generated CO gas would continue to act as a reducing gas to reduce the raw materials, and after the surface impurities were reduced, the iron oxide desulfurizer wrapped inside would be exposed, and the iron compounds in the iron oxide desulfurizer would continue to react with the reducing agent. After the reaction, the iron-carbon material was taken out from the tube furnace, and deionized water was used to soak and wash the by-product Na2S attached to the surface of the iron-carbon material until the acid-base property of the eluate was neutral; the solid material in the eluate was filtered out, and the solid material was frozen and dried to obtain zero-valent iron biochar. The source of the biochar can also be changed from corn to rice, that is, rice straw is used to reduce the waste desulfurizer to obtain zero-valent iron rice biochar.

[0069] In this example, performance optimization experiments of the iron-carbon composite material were also carried out. Different reaction conditions were set to prepare iron-carbon-based composite materials, and the parameters are as follows:

[0070] Doping ratio of waste desulfurizer: C:waste desulfurizer = 1:0.1, 1:0.5, 1:1, 1:1.5. Antibiotic degradation experiments were carried out using the prepared various composite materials to compare the degradation ability of different composite materials against antibiotics to determine the optimal preparation parameters. The antibiotic degradation experiment is as follows: A certain amount of the target composite material was added to the reaction system respectively, and different antibiotics were added at the same time to make the concentration of each antibiotic 1 mg / L. After sealing, it was placed in a shaker at 30 °C and 160 r / min for reaction. Samples were taken at specific times to measure the residual concentration of antibiotics. Two parallels were made for each system, and a blank control without adsorbent was set at the same time. The material dosage was 0.1 g, and the reaction duration was 2 h.

[0071] The removal results of antibiotics by the iron-carbon composite material prepared by carbothermal reduction method using waste desulfurizer and biochar are as Figure 4 (a) and Figure 4 (b) shown. As can be seen from Figure 4 (a) and Figure 4As can be seen from (b), for the zero-valent iron biochar prepared by doping different biomasses with waste desulfurizer in different proportions, the removal effect of antibiotics shows a similar trend. When the proportion of biomass to waste desulfurizer is C:W D = 1:0.1 (m / m) and C:W D = 1:0.5 (m / m), the effect is the best. Among them, when C:W D = 1:0.5 (m / m), the removal rates of the five antibiotics are TC: 99.4%, OTC: 99.7%, SMX: 98.3%, SMZ: 99.3%, and SZ: 99.7%, respectively. When C:W D = 1:1 (m / m) and C:W D = 1:1.5 (m / m), it will affect the removal rates of SMX and SMZ, and basically no removal effect of antibiotics is detected. This may be because too high a proportion of waste desulfurizer leads to the aggregation or surface coverage of ZVI, thus reducing the effective adsorption sites.

[0072] In this example, antibiotic degradation experiments were carried out using the prepared various composite materials, and the degradation abilities of different composite materials against antibiotics were compared to determine the optimal preparation parameters. Based on the above experimental results, in this example, the experiment selected the zero-valent iron corn biochar prepared with the proportion of corn straw to waste desulfurizer of 1:0.5 (m / m), that is, C C -W D ZVI, as the research object for subsequent experiments.

[0073] Example 4

[0074] This example discloses the application of the method for preparing zero-valent iron biochar materials using waste desulfurizer in removing antibiotics. The method for preparing zero-valent iron biochar materials using waste desulfurizer is the method in Example 1 or Example 2. Zero-valent iron biochar is prepared using the method for preparing zero-valent iron biochar materials using waste desulfurizer, and the zero-valent iron biochar is respectively added into reaction systems of various antibiotics with the same concentration to remove the antibiotics in the antibiotic reaction systems. The concentration of antibiotics in the antibiotic reaction systems can be 1 mg / L or other concentrations, which is not limited here. In this example, the antibiotic concentration of 1 mg / L is taken as an example.

[0075] This example adopts the antibiotic measurement method and antibiotic analysis method in Example 3. The time curve of the antibiotic removal rate of C C -W D ZVI, that is, zero-valent iron corn biochar, is as shown in Figure 5 shown, C C -W DThe removal of five antibiotics by ZVI generally showed an upward trend over time. The removal effect on tetracycline antibiotics was obvious, and the removal rate reached over 95% at 0.5 h and over 98% at 1 h. The removal rates of sulfonamide antibiotics were rapidly increased to SMX: 66.9%, SMZ: 95.2%, and SZ: 73.3% within 12 h, respectively, and then the removal rate increased slowly after 12 h. The highest removal rates of TC, OTC, SMX, SMZ, and SZ were 99.7%, 99.7%, 82.2%, 97.4%, and 85.7%, respectively, and there was no obvious desorption phenomenon within 72 h.

[0076] It can be seen from Figure 5 that the efficiency of ZVI in removing TC and OTC antibiotics was relatively high. Within 2 h of adsorption time, the removal rates of TC and OTC antibiotics were close to 100%. In contrast, the removal rates and efficiencies of SMX, SMZ, and SZ antibiotics were lower than those of TC and OTC antibiotics, but still had relatively high removal rates and efficiencies. For example, the time curve of the removal rate of SMZ antibiotics converged at about 12 h, that is, C -W D the removal rate of ZVI for SMZ antibiotics reached the maximum value of 95% at about 12 h and remained unchanged over time. The removal rate of SZ antibiotics was higher than that of SMX antibiotics and lower than that of SMZ antibiotics. Within 0 - 12 h, C -W D the removal rate of ZVI for SZ antibiotics increased rapidly and fluctuated within 0 - 5 h. The removal rate of SZ antibiotics was greater than 70% at 12 h and slowly increased from 12 h to 72 h, and finally reached 85.7% at 72 h. Within 0 - 12 h, C -W D the removal rate of ZVI for SMX antibiotics and SZ antibiotics had similar rules, that is, rapid increase and fluctuation. The removal rate of SMX antibiotics was greater than 65% at 12 h, and decreased first and then increased from 12 - 72 h, and finally reached 82.2% at 72 h. C -W D In this example, the removal rate curves of ZVI for five types of antibiotics, namely TC, OTC, SMX, SMZ, and SZ, were plotted. The abscissa of this curve was the adsorption time, with the unit of h, and the ordinate was the removal rate, with the unit of %.

[0077] The removal effect and efficiency of ZVI for TC and OTC antibiotics were relatively high, and the removal effect was measured by the removal rate. C -W D C -W D C -W DThe removal effect of ZVI on SZ antibiotics is higher than that on SMX antibiotics and lower than that on SMZ antibiotics. The curves of the removal rates of TC and OTC antibiotics varying with the adsorption time are similar, and the curves of the removal rates of SMX, SMZ, and SZ antibiotics varying with the adsorption time are similar.

[0078] Example 5

[0079] This example discloses the application of the method for preparing zero-valent iron biochar materials using waste desulfurizer in the removal of antibiotics. The method for preparing zero-valent iron biochar materials using waste desulfurizer is the method in Example 1 or Example 2. Zero-valent iron biochar is prepared using the method for preparing zero-valent iron biochar materials using waste desulfurizer, and the zero-valent iron biochar is respectively added into reaction systems of various antibiotics with the same concentration to remove the antibiotics in the antibiotic reaction systems. The concentration of the antibiotics in the antibiotic reaction systems can be 1 mg / L or other concentrations, which is not limited here. This example takes the antibiotic concentration of 1 mg / L as an example.

[0080] This example adopts the antibiotic measurement method and antibiotic analysis method in Example 3. This example will C C -W D ZVI, that is, zero-valent iron corn biochar, is used to identify the degradation products of SMX, analyze the possible intermediate products during the degradation process, and deduce its degradation path. A total of 9 products are detected during the SMX degradation process, and their corresponding mass-to-charge ratios (m / z), molecular weights, molecular formulas, and chemical structures are listed in Table 3.

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

[0082]

[0083] This example provides 9 products during the SMX degradation process, as well as the mass-to-charge ratios, molecular weights, molecular formulas, and chemical structures corresponding to these 9 products. All 9 products during the degradation process contain benzene rings, and compared with SMX, the 9 products during the degradation process have lower toxicity.

[0084] Example 6

[0085] This example discloses the application of the method for preparing zero-valent iron biochar material from waste desulfurizer in removing antibiotics. The method for preparing zero-valent iron biochar material from waste desulfurizer is the method in Example 1 or Example 2. Zero-valent iron biochar is prepared by using the method for preparing zero-valent iron biochar material from waste desulfurizer, and the zero-valent iron biochar is added into reaction systems of various antibiotics with the same concentration respectively to remove the antibiotics in the antibiotic reaction systems. The concentration of antibiotics in the antibiotic reaction systems can be 1 mg / L or other concentrations, which is not limited herein. This example takes the antibiotic concentration of 1 mg / L as an example.

[0086] This example adopts the antibiotic measurement method and antibiotic analysis method in Example 3. This example deduces C C -W D The degradation pathway of SMX by ZVI, that is, zero-valent iron corn biochar, is combined with the main degradation products and the microscopic changes before and after the above reactions to speculate C C -W D The main pathways for ZVI to degrade SMX are as Figure 6 shown, and there are three pathways in total, including hydroxylation, bond cleavage (synergistic reduction of zero-valent iron), and oxidation.

[0087] In degradation pathway I, ·OH generated by the reaction of ZVI with activated molecular oxygen in the system through two-electron transfer or sequential single-electron transfer attacks SMX to generate a product with m / z = 278, which conforms to the typical phenolic hydroxyl addition characteristics. The continuous attack of ·OH causes the cleavage of the sulfonamide group in the product with m / z = 278 (it may also be reduced and cleaved by the electron donor of ZVI), forming a possible product with m / z = 201 (not detected), and finally being oxidized to m / z = 123.

[0088] In degradation pathway II, ·OH oxidizes the amino group of SMX to a nitro group to generate a product with m / z = 284, and the free radical may directly attack the electron-donating group in the SMX molecule to cause its oxidation. Under the combined action of ·OH and ZVI, the S-N bond is further cleaved to form a product with m / z = 158; this product is finally oxidized to m / z = 110.

[0089] In degradation pathway III, ·OH generated by activated molecular oxygen hydroxylates SMX to generate a product with m / z = 270. Subsequently, ZVI donates electrons and jointly with the ·OH free radical destroys the S-N bond in the molecule with m / z = 270, resulting in its cleavage to form m / z = 190, and m / z = 190 undergoes a C-S bond cleavage reaction and a HO· addition reaction caused by free radical attack on the C position under continuous oxidation by free radicals, thus being transformed into m / z = 142 and m / z = 99.

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

[0091] It should be noted that in this document, the terms "including", "comprising", or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of additional identical elements in the process, apparatus, article, or method comprising such element.

[0092] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A method for preparing zero-valent iron biochar material using waste desulfurizer, characterized in that, Including: S1: Pretreat crop straws to obtain straw powders; S2: Mix the straw powders, waste desulfurizer, and Na2CO3 to obtain a mixed material; S3: Place the mixed material into a tube furnace and heat the mixed material in a nitrogen environment to reduce the waste desulfurizer; S4: Take out the mixed material from the tube furnace, remove impurities in the mixed material to obtain zero-valent iron biochar.

2. The method for preparing zero-valent iron biochar material using waste desulfurizer according to claim 1, wherein In step S2, the ratio of straw powder, waste desulfurizer, and Na2CO3 is 1:0.5:0.

75.

3. The method for preparing zero-valent iron biochar material using waste desulfurizer according to claim 1, characterized in that, In step S2, after mixing the straw powders, waste desulfurizer, and Na2CO3, use a ball mill to crush the straw powders, waste desulfurizer, and Na2CO3 for 10 min to obtain a mixed material.

4. The method for preparing zero-valent iron biochar material by using waste desulfurizer according to claim 1, wherein, The heating process in step S3 starts from the initial temperature, raises the temperature of the mixed material to 800 °C at a rate of 5 °C / min and holds for 2 h. During the heating process, introduce nitrogen into the tube furnace.

5. The method for preparing zero-valent iron biochar material by using waste desulfurizer according to claim 1, characterized in that In step S3, under the action of Na2CO3, FeS in the waste desulfurizer reacts with C in the straw powder to generate zero-valent iron and carbon monoxide.

6. The method for preparing zero-valent iron biochar material by using waste desulfurizer according to claim 1, wherein In step S3, under the action of Na2CO3, elemental sulfur in the waste desulfurizer reacts with C in the straw powder to generate Na2S and carbon monoxide.

7. The method for preparing zero-valent iron biochar material using waste desulfurizer according to claim 1, wherein In step S3, iron oxides in the waste desulfurizer react with C in the straw powder to generate zero-valent iron and carbon dioxide.

8. The method for preparing zero-valent iron biochar material using waste desulfurizer according to claim 1, characterized in that, In step S4, soak and wash the by-product Na2S attached to the surface of the iron-carbon material with deionized water until the acid-base property of the eluate is neutral; filter out the solid material in the eluate, freeze and dry the solid material to obtain zero-valent iron biochar.

9. The method for preparing zero-valent iron biochar material by using waste desulfurizer according to claim 1, characterized in that, In step S1, wash the crop straws and cut them into multiple sections, place the multiple sections of crop straws into an oven, dry them in an environment of 80 °C for 12 - 24 h to obtain dried straws; take out the dried straws, crush and sieve the dried straws to obtain straw powders.

10. Use of the method for preparing zero-valent iron biochar material from waste desulfurizer according to any one of claims 1-9 in removing antibiotics, characterized in that, Use the method for preparing zero-valent iron biochar material using waste desulfurizer to prepare zero-valent iron biochar, and add the zero-valent iron biochar into reaction systems of various antibiotics with the same concentration respectively to remove antibiotics in the antibiotic reaction systems.

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