Methods for producing straw-derived biochar material with magnetic properties enhanced by red mud and methods for using the same

Abstract

The present invention discloses a method for producing and using straw-derived biochar material with magnetic properties enhanced by red mud, which comprises drying the straw naturally or drying and then crushing it, drying the red mud in the Bayer process and crushing it into powder, then mixing the crushed straw and the powdered red mud in a ball mill to obtain a straw-red mud mixed powder, mixing the alkali metal-rich biomass ash with water and leaching to obtain a biomass ash extract and a dealkalized biomass ash solid residue, uniformly mixing and stirring the straw-red mud mixed powder and the biomass ash extract to obtain a paste-like mixture, co-pyrolyzing under a protective atmosphere, washing the magnetic straw-derived biochar produced by co-pyrolysis until it becomes neutral, and obtaining a straw-derived biochar material with magnetic properties enhanced by red mud. The present invention significantly improves the adsorption rate and adsorption amount of the straw-derived biochar to typical antibiotics fluoroquinolones, imparting magnetic properties to the straw-derived biochar, which is favorable for subsequent sorting and recycling.

Description

[Technical Field]

[0001] The present invention is in the field of solid waste resource recycling, and specifically relates to a method for producing straw-derived biochar material with enhanced magnetic properties by red mud, and methods for using the same. [Background technology]

[0002] China produces approximately 900 million tons of straw annually. With the exception of a small portion used as animal feed, this waste is primarily used as fertilizer, generating little value. Biochar and activated carbon are often used as valuable adsorbents, but biochar derived from regular straw has low adsorption capacity and therefore low value. Straw and agricultural and forestry waste are partially utilized as biomass fuel for energy generation, and the secondary waste product is primarily biomass ash. Biomass ash is alkaline and rich in nutrients such as phosphorus, magnesium, and soluble silicon. It can be used as fertilizer and to improve acidic soils. However, in the alkaline soils of vast areas of western and northern China, direct application of biomass ash exacerbates soil salinization, limiting its comprehensive utilization.

[0003] Red mud is the most widely produced non-ferrous metal waste residue in China, with 95% produced by the Bayer process, resulting in an annual production of approximately 120 million tons. While red mud produced by the Bayer process contains a certain amount of iron oxide, it is difficult to separate and concentrate, making it worthless for refining, resulting in a comprehensive utilization rate of less than 5%. Red mud deposits occupy vast areas of land and pose environmental and safety hazards, making it urgent to find a comprehensive way to utilize red mud. Provinces such as Shandong and Henan are not only major red mud-producing regions, but also food-producing regions. Therefore, combining straw and red mud could significantly reduce the burden of solid waste disposal.

[0004] Fluoroquinolone antibiotics are widely used in humans and animals because they are inexpensive, broad-spectrum, and unlikely to develop drug resistance. However, fluoroquinolone antibiotics are difficult to degrade in water, and their large-scale use leads to their accumulation in the environment, posing a significant threat to the environment. Commonly used fluoroquinolone antibiotics include ofloxacin, norfloxacin, ciprofloxacin, pefloxacin, and enoxacin. Adsorption is an important method for removing fluoroquinolone antibiotics.

[0005] Straw-derived biochar has a high ash content, a small specific surface area, weak adsorption capacity, and little economic value. The iron in red mud is difficult to concentrate through sorting, making it unworthy of refining and difficult to utilize comprehensively. Red mud has a small specific surface area and extremely low adsorption capacity for organic pollutants such as antibiotics. Therefore, adsorbents made from red mud are primarily used for inorganic pollutants such as heavy metals, with relatively little involvement with organic pollutants.

[0006] Chinese Patent Nos. 110586038 and 109847697 propose methods for efficiently removing pollutants by loading nanoscale zerovalent iron onto biochar. However, these methods require the use of iron salts or ferrous salts as the source of zerovalent iron, resulting in high production costs. Chinese Patent Nos. 107051413 and 108543517 disclose the possibility of producing magnetic materials by mixing red mud, a carbon source, and a binder and calcining the mixture in an oxygen barrier, thereby concentrating and recovering heavy metal ions in wastewater, and using the red mud to produce magnetic adsorbents. Chinese Patent Application Publication No. 106362685 discloses a method for removing arsenic from water using the co-pyrolysis products of red mud and biomass. Although Chinese Patent Publication No. 113522238 introduces a red mud-based iron-carbon composite material for removing heavy metals from wastewater, as well as its manufacturing and use methods, the method requires the red mud to be treated with an acid solution, which preliminarily involves dealkalization, resulting in the generation of a large amount of acidic wastewater, and does not demonstrate that the adsorption performance of the composite material is better than that of the original biochar. The biochar material has drawbacks, such as a complicated and expensive manufacturing process, and is not suitable for recycling solid wastes such as straw and red mud. Furthermore, the produced biochar material is primarily targeted at heavy metals. Summary of the Invention [Problem to be solved by the invention]

[0007] The objectives of the present invention are as follows: To overcome the drawbacks of the prior art, the present invention provides a method for producing straw-derived biochar material with magnetic properties enhanced by red mud, which can improve the quality and value of the integrated product by cooperatively utilizing red mud, biomass ash, and straw, realize the reuse of solid waste, and generate economic benefits. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention employs the following technical means.

[0009] The method for producing straw-derived biochar material with magnetic properties enhanced by red mud is as follows: The first step is to dry the straw naturally or dry it and then grind it. The second step in the Bayer process is to dry the red mud and crush it into powder. a third step of mixing the crushed straw from the first step with the powdered red mud from the second step in a ball mill to obtain a straw-red mud mixed powder; a fourth step of mixing and leaching the alkali metal-enriched biomass ash with water to obtain a biomass ash extract and a dealkalized biomass ash solid residue; A fifth step of uniformly mixing and stirring the straw-red mud mixed powder from the third step and the biomass ash extract obtained in the fourth step to obtain a paste-like mixture; and a sixth step of co-pyrolyzing the paste-like mixture from the fifth step under a protective atmosphere at a pyrolysis temperature of 400 to 1000°C (preferably 500 to 850°C) and a heat-keeping time of 10 minutes to 5 hours (preferably 30 minutes to 3 hours), and washing the magnetic straw-derived biochar produced by the co-pyrolysis with water until it becomes neutral, thereby obtaining a straw-derived biochar material whose magnetism has been reinforced with red mud.

[0010] Specifically, in the first step, the straw is air-dried or dried until the moisture content is less than 5 wt%, and then crushed to 120 mesh or less. In the second step, the Fe2O3 content in the red mud is increased to 30 wt% or more, and the red mud and straw are dried until the moisture content is less than 2 wt%. The red mud and straw are dried before ball milling to prevent residual moisture from adhering to the ball mill pot and affecting the effectiveness.

[0011] Specifically, in the third step, the powdered red mud, which accounts for 5% to 85% by mass, preferably 10% to 65% by mass of the total mixture, is mixed with straw in a ball mill for 4 to 72 hours, preferably 12 to 24 hours. The mixing and nesting of the two types of material particles is achieved in the mechanical process of the ball mill.

[0012] Specifically, in the fourth step, the alkali metal-rich biomass ash is selected from one or a mixture of two or more of hardwood ash, wheat straw ash, rice husk ash, cotton stalk ash, and sunflower stalk ash. The biomass ash and water are mixed in a mass ratio of 1:0.5 to 4 (preferably 1:1 to 1.5). The leaching method involves filtration separation after solid-liquid mixing, or column-type diafiltration leaching. The biomass ash extract produced after leaching is rich in alkaline substances, improving the quality of the straw-derived biochar. The remaining low-alkaline solid is rich in phosphorus, magnesium, and soluble silicon, with a reduced amount of easily soluble substances. The resulting dealkalized biomass ash solid residue can be used as fertilizer, reducing the risk of soil salinization.

[0013] Preferably, in the fifth step, the straw-red mud mixed powder and the biomass ash extract are mixed in a mass ratio of 1:0.2-4, and the straw-red mud mixed powder and the biomass ash extract are uniformly stirred to form a paste-like mixture, which is then left to stand for 0.5-2 hours to allow a sufficient solid-liquid reaction to occur, allowing the ions in the biomass ash extract and the soluble alkali metals in the red mud to diffuse into the interior of the straw particles with the aid of water.

[0014] Preferably, in the sixth step, the protective atmosphere is nitrogen gas, and the flow rate of the nitrogen gas per minute is 3% to 30% of the volume of the furnace, to prevent oxygen gas from entering the furnace and oxidizing the product, and to prevent a decrease in the production amount due to a high flow rate.

[0015] During the co-pyrolysis reaction, alkali reacts with carbon to promote the development of pores in the biochar, and iron oxide in the red mud is reduced to produce iron oxide and elemental iron, which are the source of the material's magnetism and give the biochar material its magnetic properties. During the pyrolysis process, alkali metals and elements such as Fe, Si, Al, Na, and Ti in the red mud react with the biochar in a solid state, forming a homogeneous structure at the submicron level and improving the adsorption sites of the straw-derived biochar.

[0016] Furthermore, a straw-derived biochar material having enhanced magnetic properties due to red mud produced by the above-mentioned production method is also within the scope of protection of the present invention.

[0017] Additionally, the present invention seeks protection for a method of using straw-derived biochar material, further enhanced with magnetic properties by red mud, as an adsorbent in sewage treatment.

[0018] Furthermore, the present invention seeks protection for a method of using the straw-derived biochar material, which has been enhanced with magnetic properties by red mud, as an adsorbent for removing fluoroquinolone antibiotics from water in sewage treatment, specifically: Step S1: uniformly mixing the straw-derived biochar material, the magnetic properties of which have been reinforced by red mud, with the sewage to be treated, and sufficiently adsorbing the fluoroquinolone antibiotics in the sewage; Step S2: Separating the straw-derived biochar material, which has been enhanced in magnetism by the red mud to which the fluoroquinolone antibiotics have been adsorbed, from the wastewater after the treatment by magnetic force; Step S3: Pyrolyzing and regenerating the straw-derived biochar material with the magnetic properties enhanced by the red mud to which the separated fluoroquinolone antibiotics are adsorbed at 300 to 700 °C in a protective atmosphere for 10 to 60 minutes; and step S4, in which the straw-derived biochar material, the magnetic properties of which have been enhanced by the red mud pyrolyzed and regenerated in step S3, is reused to adsorb fluoroquinolone antibiotics in sewage.

[0019] In step S3, the temperature for pyrolysis and regeneration must be at least 100°C lower than the initial production temperature of the straw-derived biochar material enhanced with magnetic properties by red mud, so as to decompose the adsorbed fluoroquinolone antibiotics without changing the main structure of the biochar. Furthermore, the magnetic particles that were partially oxidized during use are regenerated under a high-temperature reducing atmosphere.

[0020] Specifically, the fluoroquinolone antibiotics include at least one of ofloxacin, norfloxacin, ciprofloxacin, pefloxacin, enoxacin, and the like, but are not limited thereto. [Effects of the Invention]

[0021] (1) This invention improves the utility and economic value of straw-derived biochar and red mud, enabling the collaborative utilization of various solid wastes. The straw-derived biochar produced by this method is less expensive than expensive nanoscale zero-valent iron composite biochar, has high performance, and is magnetic, facilitating recycling by magnetic separation after adsorption saturation. Furthermore, it can be recycled by pyrolysis, exhibiting excellent recycling performance, significantly improving the usefulness and commercial value of straw-derived biochar as an adsorbent. Provinces such as Shandong and Henan are not only major food-producing regions but also have thriving aluminum industries, resulting in large production volumes of straw and red mud. This method not only provides a valuable resource for straw and red mud, but also reduces greenhouse gas emissions during straw utilization compared to conventional methods and reduces the risk of land salinization during biomass ash utilization.

[0022] (2) This invention processes two types of solid waste, straw and red mud, through ball milling, biomass ash extraction + liquid impregnation, co-pyrolysis, etc., to homogeneously combine iron and carbon elements at the submicron scale, providing a large number of highly efficient adsorption points. This significantly improves the adsorption rate and amount of fluoroquinolone antibiotics on straw-derived biochar, and also imparts magnetic properties to the straw-derived biochar, facilitating sorting and recycling. The recycled adsorbent can be decomposed by pyrolysis to decompose the adsorbed fluoroquinolone antibiotics, allowing it to be recycled multiple times, realizing waste-to-waste treatment and improving the utility and economic value of straw-derived biochar.

[0023] (3) The straw-derived biochar used in this invention can be recycled by simple magnetism and then pyrolyzed and regenerated. The performance of the recycled product is minimally attenuated, allowing it to be reused multiple times, significantly reducing usage costs and improving product value. At temperatures between 300 and 700°C, the adsorbed fluoroquinolone antibiotics are decomposed, restoring the adsorption performance of the straw-derived biochar. Even after 10 repeated uses, no degradation of adsorption performance was observed. [Brief explanation of the drawings]

[0024] The above and / or other advantages of the present invention will become more apparent from the following more detailed description of the invention taken in conjunction with the accompanying drawings and specific embodiments.

[0025] [Figure 1] FIG. 1 shows the effect of antibiotic removal rate of straw-derived biochar material with magnetic properties reinforced by red mud in Example 1. [Figure 2] FIG. 1 shows the effect of magnetic separation of straw-derived biochar material whose magnetism has been reinforced with red mud in Example 1. [Figure 3] FIG. 1 shows a scanning electron microscope photograph and element distribution of straw-derived biochar material with enhanced magnetism using red mud in Example 1. [Figure 4] FIG. 10 shows the effect of antibiotic removal rate after 10 cycles of straw-derived biochar material with magnetic properties enhanced by red mud in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention can be better understood from the following examples.

[0027] Example 1 1. Production of biochar from magnetic straw 1. Preparation of raw materials The straw was collected from the wheat straw farm in Lianyungang, Jiangsu Province, and the red mud was collected from a red mud storage facility of an aluminum oxide company in Shandong Province. The water used was ultrapure water produced in a laboratory. The straw was cut and dried in an oven at 105°C until a constant weight was reached. It was then crushed using a blade-type Chinese medicine crusher and sieved through a 125 μm sieve (120 mesh). The red mud was dried in an oven at 105°C until a constant weight was reached, crushed using a jaw crusher, and sieved through a 50 mesh sieve. The straw and red mud were added to a ball mill pot in a 9:1 ratio and milled at 350 rpm for 16 hours before being removed and designated raw material mixture A.

[0028] Biomass ash was obtained by burning wheat straw in a muffle furnace at 1000°C until a certain weight was reached. Biomass ash and water were mixed in a beaker at a ratio of 1:4, heated to 60°C, and stirred for 2 hours. The mixture was then filtered for solid-liquid separation. The resulting solution was designated biomass ash extract B.

[0029] 2. Production of magnetic biochar Raw material mixture A and biomass ash extract B were mixed uniformly in a 1:2 mass ratio using a glass rod in a quartz glass boat. The quartz glass boat was then transferred to a tubular furnace, which was then sealed. Nitrogen gas was introduced at a rate of 300 ml / min to expel oxygen from the tube, and the mixture was left to stand for 60 minutes to thoroughly mix the solid and liquid. The temperature was then increased to 500°C at a rate of 10°C / min and maintained at this temperature for 120 minutes. The mixture was then cooled to room temperature in the furnace and removed, yielding straw-derived biochar material with enhanced magnetic properties from red mud.

[0030] 3. Adsorption of fluoroquinolone antibiotics For comparison, we investigated (1) the straw-derived biochar material (MBC) with enhanced magnetism by red mud obtained in this step, (2) wheat straw-derived biochar (BC) produced under the same pyrolysis conditions, and (3) magnetic biochar (BC + Fe) obtained by chemically precipitating zero-valent iron nanoparticles onto the wheat straw-derived biochar. 0 (4) Magnetic biocarbon (BC+Fe3O4-NP), obtained by chemically precipitating iron oxide nanoparticles onto the straw-derived biochar (BC+Fe3O4-NP), was added to 50 ml of a 20 mg / L ofloxacin solution. Three parallel experiments were performed for each group, and the mixture was mixed on a shaker. Changes in the ofloxacin antibiotic concentration were monitored by periodic sampling. The results are shown in Figure 1.

[0031] Magnetic biochar (BC+Fe 0 The manufacturing method of BC-NP is as follows: 1.0 g of BC and 0.15 g of FeCl3·6H2O are added to 75% ethanol, and the mixture is stirred for 60 minutes. 10 ml of 10 g / L NaBH4 solution is slowly added dropwise under a nitrogen gas atmosphere, and the mixture is stirred for 30 minutes. After that, the mixture is filtered and separated to obtain BC+Fe 0 -Gain NP.

[0032] The magnetic biochar (BC+Fe3O4-NP) was prepared as follows: 0.1 g of FeCl3·6H2O and 0.0368 g of FeCl2·4H2O were dissolved in distilled water under a nitrogen gas atmosphere, 1.0 g of BC was added, and the mixture was mechanically stirred for 30 minutes. Ammonia water was added dropwise to adjust the pH to between 10 and 11. The mixture was heated to 80°C and stirred for 30 minutes, during which nitrogen gas was continuously introduced and ammonia water was added to maintain the pH between 10 and 11. The mixture was then filtered and separated to obtain BC+Fe3O4-NP. 0.1 g of MBC, BC, and BC+Fe were added. 0 -NP and BC+Fe3O4-NP were weighed.

[0033] The antibiotic removal rate of wheat straw-derived biochar (BC) obtained by direct pyrolysis could not exceed 90%, and the equilibration time was long and the curve growth was slow. Furthermore, biochar modified by chemical precipitation of expensive nanoscale zero-valent iron or iron oxide nanoparticles (BC+Fe) was significantly higher than that of biochar modified by chemical precipitation of expensive nanoscale zero-valent iron or iron oxide nanoparticles (BC+Fe). 0 The use of red mud-based magnetic materials (i.e., Fe3O4-NP and BC+Fe3O4-NP) significantly shortened the equilibration time and improved treatment efficiency, but failed to improve the removal rate. It was found that iron oxide in red mud was reduced to produce iron oxide and iron, which are the source of the material's magnetism and confer magnetism to the biochar material. Furthermore, as shown in Figure 3, during pyrolysis, alkali metals and elements such as Fe, Si, Al, Na, and Ti in the red mud reacted with the biochar in a solid state, forming a homogeneous submicron structure and improving the adsorption rate of the straw-derived biochar. The use of straw-derived biochar materials (MBC) enhanced with magnetic properties by red mud obtained in this invention significantly improved both adsorption efficiency and removal rate, achieving better results than expensive nanomaterials using solid waste as raw materials.

[0034] 4.Magnetic separation After the experiment was completed, a magnet was used to separate the straw-derived biocarbon magnetic reinforcement material with red mud, facilitating its recycling (see Figure 2). It was found that the magnetic properties generated by a simple magnet allowed the straw-derived biochar material, which had been magnetically reinforced with red mud and had fluoroquinolone antibiotics adsorbed thereon, to be separated from the water.

[0035] Example 2 1. Production of biochar from magnetic straw 1. Preparation of raw materials The straw was collected from a wheat straw farm in Nanjing, Jiangsu Province, and the red mud was collected from the red mud outlet of a gauge press at an aluminum oxide company in Henan Province. The water used was ultrapure water produced in a laboratory. The straw was cut and dried in an oven at 105°C until a constant weight was reached. It was then crushed using a blade-type Chinese medicine crusher and sieved through a 125 μm sieve (120 mesh). The red mud was dried in an oven at 105°C until a constant weight was reached, crushed using a jaw crusher, and sieved through a 50-mesh sieve. The straw and red mud were added to a ball mill pot in a 2:1 ratio and milled at 350 rpm for 5 hours before being removed and designated raw material mixture A'.

[0036] A mixture of plane tree branches and leaves was burned in a muffle furnace at 900°C until a constant weight was reached, yielding biomass ash. The biomass ash was placed in a Plexiglas column, and water was pumped from bottom to top using a peristaltic pump. The diafiltration method was used to extract the biomass ash. An extract equal in weight to the previous biomass ash was collected and designated biomass ash extract B'.

[0037] 2. Production of magnetic biochar Raw material mixture A' and biomass ash extract B' were mixed uniformly in a quartz glass boat at a mass ratio of 1:0.5 using a glass rod. The quartz glass boat was then transferred to a tubular furnace, which was then sealed. Nitrogen gas was introduced at a rate of 300 ml / min to expel oxygen from the tube, and the mixture was left to stand for 60 minutes to thoroughly mix the solid and liquid. The mixture was then heated to 800°C at a rate of 10°C / min and held at that temperature for 120 minutes. The mixture was then cooled to room temperature in the furnace and removed, yielding straw-derived biochar material with enhanced magnetic properties from red mud.

[0038] 3. Adsorption of fluoroquinolone antibiotics 0.3 g of straw-derived biochar material with magnetic properties reinforced by red mud was weighed and added to 50 ml of ciprofloxacin antibiotic solution with a concentration of 20 mg / L. After equilibration on a shaker for 24 hours, the concentration of ciprofloxacin antibiotic was measured and the removal rate was calculated.

[0039] 4. Recycle and reuse After the adsorption experiment, the straw-derived biochar material, whose magnetic properties were enhanced by red mud, was separated by magnetic force and regenerated by pyrolysis at 700°C in a tubular furnace under a nitrogen gas atmosphere. The regenerated straw-derived biochar material, whose magnetic properties were enhanced by red mud, was subsequently used to adsorb the antibiotic ciprofloxacin.

[0040] Repeat steps 3 and 4. As can be seen from Figure 4, after 10 cycles of use, the antibiotic removal efficiency of the straw-derived biochar material enhanced with magnetic properties by red mud did not decrease significantly, demonstrating stable recycling performance and significant reduction in usage costs.

[0041] The present invention provides a method for producing and using straw-derived biochar material with magnetic properties enhanced by red mud. There are many methods and approaches for specifically realizing this technical means. It should be noted that the above description is merely a preferred embodiment of the present invention. Those skilled in the art can make further improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Each component not specified in this example can be realized using conventional technology.

[0042] (Addendum) (Appendix 1) A method for producing straw-derived biochar material with magnetic properties enhanced by red mud, comprising: The first step is to dry the straw naturally or dry it and then grind it. The second step in the Bayer process is to dry the red mud and crush it into powder. a third step of mixing the crushed straw from the first step with the powdered red mud from the second step in a ball mill to obtain a straw-red mud mixed powder; a fourth step of mixing and leaching the alkali metal-enriched biomass ash with water to obtain a biomass ash extract and a dealkalized biomass ash solid residue; A fifth step of uniformly mixing and stirring the straw-red mud mixed powder from the third step and the biomass ash extract obtained in the fourth step to obtain a paste-like mixture; and a sixth step of co-pyrolyzing the paste-like mixture from the fifth step under a protective atmosphere at a pyrolysis temperature of 400 to 1000°C for a heat retention time of 10 minutes to 5 hours, and washing the magnetic straw-derived biochar produced by the co-pyrolysis with water until it becomes neutral, thereby obtaining a straw-derived biochar material with magnetic properties reinforced by red mud.

[0043] (Appendix 2) A method for producing a straw-derived biochar material with enhanced magnetic properties using red mud according to Appendix 1, characterized in that in a first step, the straw is naturally dried or dried until the moisture content is less than 5 wt%, and then crushed to 120 mesh or less; and in a second step, the Fe2O3 content in the red mud is increased to 30 wt% or more, and the red mud is dried until the moisture content is less than 2 wt%.

[0044] (Appendix 3) A method for producing a straw-derived biochar material with enhanced magnetic properties by red mud according to Appendix 1, characterized in that in the third step, powdered red mud, which accounts for 5% to 85% by mass of the total mixture, is mixed with straw in a ball mill, and the mixing time is 4 to 72 hours.

[0045] (Appendix 4) The method for producing a straw-derived biochar material with enhanced magnetic properties using red mud according to Appendix 1, characterized in that in the fourth step, the alkali metal-rich biomass ash is selected from one or a mixture of two or more of hardwood ash, wheat straw ash, rice husk ash, cotton stalk ash, and sunflower stalk ash, the biomass ash and water are mixed in a mass ratio of 1:0.5 to 1:4, the leaching method uses filtration separation after solid-liquid mixing, or column-type diafiltration leaching, and the dealkalized biomass ash solid residue produced after leaching is used as fertilizer.

[0046] (Appendix 5) The method for producing a straw-derived biochar material with enhanced magnetism by red mud according to Appendix 1, characterized in that in the fifth step, the straw-red mud mixed powder and the biomass ash extract are mixed in a mass ratio of 1:0.2-4, and the straw-red mud mixed powder and the biomass ash extract are uniformly stirred to form a paste-like mixture, which is then left to stand for 0.5-2 hours to allow a sufficient solid-liquid reaction to occur, thereby diffusing the ions in the biomass ash extract and the soluble alkali metals in the red mud into the interior of the straw particles with the aid of water.

[0047] (Appendix 6) A straw-derived biochar material having enhanced magnetic properties due to red mud, produced by the manufacturing method described in any one of appendices 1 to 5.

[0048] (Appendix 7) 10. A method of use of the red mud magnetically enhanced straw-derived biochar material described in Appendix 6 as an adsorbent in wastewater treatment.

[0049] (Appendix 8) 10. A method of using the straw-derived biochar material with magnetic properties enhanced by red mud according to claim 6 as an adsorbent in sewage treatment for removing fluoroquinolone antibiotics from water, comprising: Step S1: uniformly mixing the straw-derived biochar material, the magnetic properties of which have been reinforced by red mud, with the sewage to be treated, and sufficiently adsorbing the fluoroquinolone antibiotics in the sewage; Step S2: Separating the straw-derived biochar material, which has been enhanced in magnetism by the red mud to which fluoroquinolone antibiotics have been adsorbed, from the wastewater after treatment by magnetic force; Step S3: The straw-derived biochar material, which has been enhanced in magnetism by red mud and to which the separated fluoroquinolone antibiotics have been adsorbed, is pyrolyzed and regenerated in a protective atmosphere at 300-700°C for 10-60 minutes. and step S4, in which the straw-derived biochar material whose magnetism has been enhanced by the red mud pyrolyzed and regenerated in step S3 is reused for the adsorption of fluoroquinolone antibiotics in sewage.

[0050] (Appendix 9) The method of claim 8, wherein the fluoroquinolone antibiotic includes at least one of ofloxacin, norfloxacin, ciprofloxacin, pefloxacin, and enoxacin.

Claims

1. A method for producing straw-derived biochar material with magnetic properties enhanced by red mud, comprising: A first step of air-drying or drying and then grinding the straw; A second step in the Bayer process involves drying the red mud and crushing it into powder. A third step of mixing the crushed straw from the first step with the powdered red mud from the second step in a ball mill to obtain a straw-red mud mixed powder; a fourth step of mixing and leaching the alkali metal-enriched biomass ash with water to obtain a biomass ash extract and a dealkalized biomass ash solid residue; A fifth step of uniformly mixing and stirring the straw-red mud mixed powder from the third step and the biomass ash extract obtained in the fourth step to obtain a paste-like mixture; a sixth step of co-pyrolyzing the paste mixture from the fifth step under a protective atmosphere, the pyrolysis temperature being 400-1000°C and the incubation time being 10 minutes-5 hours, and washing the magnetic straw-derived biochar produced by the co-pyrolysis with water until it becomes neutral, thereby obtaining a straw-derived biochar material with enhanced magnetic properties due to red mud; In the first step, the straw is air-dried or dried until the moisture content is less than 5 wt%, and then crushed to 120 mesh or less. In the second step, the Fe in the red mud is ２ O ３ The content is increased to 30 wt% or more, and the mixture is dried until the moisture content is less than 2 wt%. In the third step, the powdered red mud, which is 5% to 85% by weight of the total mixture, is mixed with the straw in a ball mill, and the mixing time is 4 to 72 hours. A method for producing straw-derived biochar material with enhanced magnetic properties using red mud.

2. 2. The method for producing straw-derived biochar material with enhanced magnetic properties by red mud according to claim 1, wherein in the fourth step, the alkali metal-rich biomass ash is selected from one or a mixture of two or more of hardwood ash, wheat straw ash, rice husk ash, cotton stalk ash, and sunflower stalk ash, the biomass ash and water are mixed in a mass ratio of 1:0.5 to 1:4, and the leaching method uses filtration separation after solid-liquid mixing or column-type diafiltration leaching, and the dealkalized biomass ash solid residue produced after leaching is used as fertilizer.

3. The method for producing a straw-derived biochar material with enhanced magnetism by red mud according to claim 1, characterized in that in the fifth step, the straw-red mud mixed powder and the biomass ash extract are mixed in a mass ratio of 1:0.2-4, and the straw-red mud mixed powder and the biomass ash extract are uniformly stirred to form a paste-like mixture, which is then left to stand for 0.5-2 hours to allow a sufficient solid-liquid reaction, and the ions in the biomass ash extract and the soluble alkali metals in the red mud are diffused into the interior of the straw particles with the aid of water.

4. A method of using a straw-derived biochar material having magnetic properties reinforced by red mud, produced by the manufacturing method described in any one of claims 1 to 3, as an adsorbent in sewage treatment.

5. 10. A method for using the straw-derived biochar material with magnetic properties enhanced by red mud according to claim 4 as an adsorbent in sewage treatment to remove fluoroquinolone antibiotics from water, comprising: Step S1: uniformly mixing the straw-derived biochar material, the magnetic properties of which have been reinforced by red mud, with the sewage to be treated, and sufficiently adsorbing the fluoroquinolone antibiotics in the sewage; Step S2: Separating the straw-derived biochar material, which has been enhanced in magnetism by the red mud to which the fluoroquinolone antibiotics have been adsorbed, from the wastewater after the treatment by magnetic force; Step S3: Pyrolyzing and regenerating the straw-derived biochar material with the magnetic properties enhanced by the red mud to which the separated fluoroquinolone antibiotics are adsorbed at 300-700°C in a protective atmosphere for 10-60 minutes. and step S4, in which the straw-derived biochar material whose magnetism has been enhanced by the red mud pyrolyzed and regenerated in step S3 is reused for the adsorption of fluoroquinolone antibiotics in sewage.

6. The method of claim 5, wherein the fluoroquinolone antibiotic comprises at least one of ofloxacin, norfloxacin, ciprofloxacin, pefloxacin, and enoxacin.

Images