Modified corn straw biochar as well as preparation method and application thereof

Abstract

The invention provides modified corn straw biochar as well as a preparation method and application thereof, and relates to the technical field of new pollutant treatment. The preparation method of the modified corn straw biochar comprises the following steps: mixing corn straw biochar powder with water to obtain a biochar suspension, adding a precursor into the biochar suspension, adjusting the pH value to 11-12 by using a sodium hydroxide solution, filtering to obtain an iron-manganese hydroxide precipitate, washing, drying and carbonizing to obtain the modified corn straw biochar. The modified corn straw biochar prepared by the preparation method disclosed by the invention can efficiently and stably adsorb sulfamethoxazole pollutants in soil, firmly bind sulfamethoxazole in situ, prevent the sulfamethoxazole from migrating and improve the bioavailability of the sulfamethoxazole. The invention provides a technical direction for safely and efficiently removing soil pollutants with low adsorbability and strong mobility in soil.

Description

Technical Field

[0001] This invention belongs to the field of new pollutant treatment technology, specifically relating to a modified corn straw biochar, its preparation method, and its application. Background Technology

[0002] The widespread use of antibiotics in human medicine and veterinary medicine has led to their prevalence as a new type of pollutant globally. In intensive livestock and poultry farming, antibiotics are frequently used as veterinary drugs. However, most antibiotics are not completely metabolized in animals, with approximately 30% to 90% of the active ingredients being excreted through feces and urine. This livestock and poultry manure containing antibiotic residues is applied to farmland as organic fertilizer, becoming a major source of soil antibiotic pollution. Once in the soil environment, antibiotics not only pose a direct threat to the soil ecosystem but may also pose potential risks to human health through crop uptake, food chain transmission, and groundwater seepage.

[0003] Sulfamethoxazole (SMX), a typical representative of sulfonamide antibiotics, has become one of the most frequently detected antibiotic contaminants in water and soil. The molecular characteristics of SMX result in extremely high risks in the environment. It exhibits low adsorption and high mobility in soil, easily infiltrating and contaminating deep soil layers and groundwater, directly threatening drinking water safety. SMX residues in the environment may pose multiple threats to ecosystems, such as inhibiting natural microbial communities and key biochemical processes, affecting soil fertility and element cycling, and disrupting soil microbial ecology; it can also be toxic to plants, inhibiting crop growth; and it can induce the generation and spread of antibiotic resistance genes, exacerbating public health risks.

[0004] Currently, remediation technologies for organic pollutants in soil mainly include chemical oxidation, biodegradation, and physical adsorption. While chemical oxidation is highly efficient, it is typically costly and may introduce chemical reagents, causing secondary pollution. Biodegradation is limited by environmental conditions and microbial activity, resulting in a long remediation cycle. In contrast, adsorption is considered a highly promising remediation approach due to its simplicity, low cost, and wide applicability. Biochar, a carbon-rich porous material formed by the pyrolysis of biomass under anaerobic or hypoxic conditions, is widely studied as an environmentally friendly adsorbent for immobilizing heavy metals and organic pollutants in soil due to its large specific surface area, well-developed pore structure, and abundant surface functional groups. However, raw biochar has limited adsorption capacity for certain specific pollutants (such as SMX, a highly polar and mobile organic compound), failing to achieve efficient removal of target pollutants. Therefore, there is an urgent need to develop a contaminated soil remediation technology that can efficiently, safely, and economically remove SMX residues from the environment. Summary of the Invention

[0005] To address the aforementioned technical problems, the primary objective of this invention is to provide a method for preparing modified corn straw biochar.

[0006] A second objective of this invention is to provide modified corn stalk biochar obtained by the above-described preparation method.

[0007] A third objective of this invention is to provide a soil remediation agent.

[0008] The fourth objective of this invention is to provide the application of the above-mentioned modified corn straw biochar or the above-mentioned soil remediation agent in adsorbing or immobilizing sulfamethoxazole in soil.

[0009] The fifth objective of this invention is to provide the application of the modified corn stalk biochar or the soil remediation agent described above in improving soil aggregate structure and / or enhancing water and fertilizer retention capacity.

[0010] To achieve the above-mentioned objectives, the technical solution of this invention is as follows: This invention provides a method for preparing modified corn straw biochar, comprising the following steps: Corn stalk biochar powder is mixed with water to obtain a biochar suspension. A precursor is added to the biochar suspension, and the pH value is adjusted to 11-12 with sodium hydroxide solution. The mixture is filtered to obtain an iron-manganese hydroxide precipitate, which is then washed, dried, and carbonized to obtain modified corn stalk biochar. The precursor includes ferric chloride solution and manganese chloride solution. The concentration of the manganese chloride solution is 0.002-0.004 mol / L, and the concentration of the ferric chloride solution is 0.004-0.010 mol / L.

[0011] In one embodiment, the corn stalk biochar powder is pulverized to pass through an 80-120 mesh sieve, and the mass ratio of the corn stalk biochar powder to water is 1:35-45.

[0012] In one embodiment, the molar ratio of the manganese chloride solution to the ferric chloride solution is 1:1 to 3.

[0013] As one implementation, the rinsing continues until the pH of the effluent remains constant.

[0014] In one embodiment, the drying temperature is 80~105℃.

[0015] In one embodiment, the carbonization temperature is 300~400℃ and the time is 1.5~2.5 h.

[0016] The present invention also provides modified corn straw biochar obtained by the above preparation method.

[0017] The present invention also provides a soil remediation agent, comprising the above-mentioned modified corn stalk biochar.

[0018] The present invention also provides the application of the above-mentioned modified corn straw biochar or the above-mentioned soil remediation agent in adsorbing or immobilizing sulfamethoxazole in soil.

[0019] The present invention also provides the application of the above-mentioned modified corn straw biochar or the above-mentioned soil remediation agent in improving soil aggregate structure and / or enhancing water and fertilizer retention capacity.

[0020] The advantages of this invention compared to existing technologies are as follows: 1. This invention utilizes a co-precipitation synthesis method involving corn straw biochar powder and a precursor-iron-manganese chloride mixture. This process generates and anchors highly dispersed iron-manganese oxide active sites onto a high-specific-surface-area carrier of corn straw biochar, forming a unique composite structure. This structure exhibits high affinity and adsorption capacity for highly mobile and environmentally hazardous sulfamethoxazole molecules through multiple synergistic mechanisms, including pore filling, hydrogen bonding, π-π electron donor-acceptor interactions, and surface complexation with metal oxides. Sulfamethoxazole is firmly adsorbed and immobilized within the modified corn straw biochar matrix, achieving an adsorption capacity of 7.43 mg / kg, a significant 5-fold improvement in adsorption performance. It also demonstrates good efficacy under SMX pollution scenarios ranging from 1 to 20 mg / L, effectively reducing the bioavailability and migration of sulfamethoxazole, avoiding the risk of generating unknown intermediate products during adsorption and immobilization, and making the soil remediation process controllable and safer. Furthermore, the modified corn straw biochar itself is composed of environmentally friendly carbon, iron, and manganese elements, and will not introduce secondary pollution after application to soil.

[0021] 2. This invention uses corn stalks as raw material to transform a high-volume, costly agricultural waste into a high-value-added environmental remediation material, achieving "turning waste into treasure." This not only significantly reduces raw material costs but also aligns with the strategic needs of a circular economy and sustainable development, possessing broad prospects for widespread application.

[0022] 3. The modified corn stalk biochar prepared by the method of this invention is a biochar-based material. While remediating soil pollution, it can also leverage the inherent advantages of biochar as a soil conditioner, improving soil aggregate structure and enhancing water and fertilizer retention capacity. Furthermore, converting biomass carbon into stable biochar and applying it to the soil is an effective carbon sequestration method, which has positive significance for mitigating climate change. Attached Figure Description

[0023] Figure 1 The adsorption kinetics curves of modified corn straw biochar on soil SMX are shown. Figure 2 Adsorption isotherm curves of modified corn straw biochar on soil SMX. Detailed Implementation

[0024] This invention provides a method for preparing modified corn stalk biochar, comprising the following steps: mixing corn stalk biochar powder with water to obtain a biochar suspension; adding a precursor to the biochar suspension; adjusting the pH value to 11-12 with sodium hydroxide solution; filtering to obtain an iron-manganese hydroxide precipitate; rinsing, drying, and carbonizing to obtain modified corn stalk biochar; wherein the precursor comprises an iron chloride solution and a manganese chloride solution; the concentration of the manganese chloride solution is 0.002-0.004 mol / L, and the concentration of the iron chloride solution is 0.004-0.010 mol / L.

[0025] The preparation method of the corn stalk biochar powder in this invention includes the following steps: washing and drying the corn stalks, then pulverizing them to obtain corn stalk powder; pyrolyzing the corn stalk powder at 400-600℃ for 1.5-2.5 h, and then pulverizing again. In this invention, the drying temperature is 60-80℃, preferably 65℃, 70℃, or 75℃; after drying, the corn stalks are pulverized, and the corn stalk powder is sieved through a 2-3 mm standard sieve to collect corn stalk powder with uniform particle size. Then, the corn stalk powder is pyrolyzed in an anaerobic environment, which is achieved by introducing an inert gas. As one embodiment, the inert gas includes argon; the pyrolysis temperature is increased to 400-600℃ at a heating rate of 10℃ / min, preferably 450℃, 500℃, or 550℃; the pyrolysis time is 1.5-2.5 h, preferably 2 h. After pyrolysis, corn stalk biochar is obtained. The furnace body is naturally cooled to room temperature under the protection of inert gas. Then, it is washed with deionized water to remove surface impurities until the conductivity of the effluent is constant. After washing, it is dried at a temperature of 50~70℃ and ground through an 80~120 mesh sieve to obtain corn stalk biochar powder with a pore size of 0.1~0.3 mm.

[0026] In this invention, corn stalk biochar powder is added to water at a mass ratio of 1:35-45 to obtain a biochar suspension, preferably 1:40. The mixture is then ultrasonically treated at a temperature of 20-30℃ for 20-40 minutes, preferably 21℃, 23℃, 25℃, 27℃, or 29℃. The ultrasonic frequency is 35-45 kHz, and the ultrasonic treatment time is preferably 25 minutes, 30 minutes, or 35 minutes. This invention promotes the dispersion of corn stalk biochar powder through ultrasonic treatment.

[0027] In this invention, a mixed solution of ferric chloride and manganese chloride is added to a biochar suspension; the concentration of the manganese chloride solution is 0.002~0.004 mol / L, preferably 0.002 mol / L, 0.003 mol / L or 0.004 mol / L; the concentration of the ferric chloride solution is 0.004~0.010 mol / L, preferably 0.005 mol / L, 0.006 mol / L, 0.007 mol / L, 0.008 mol / L or 0.009 mol / L; the molar ratio of the manganese chloride solution to the ferric chloride solution is 1:1~3, preferably 1:1.5, 1:2 or 1:2.5. Then, use a stirrer to continuously stir for 0.3 to 0.8 hours, preferably 0.4 hours, 0.5 hours, 0.6 hours, or 0.7 hours; during the stirring process, slowly add 4 to 6 mol / L sodium hydroxide solution dropwise until the pH value is 11 to 12, preferably 5 mol / L.

[0028] After stirring, the iron-manganese hydroxide precipitate is obtained by filtration. As an optional implementation, the filtration is performed using a vacuum filtration pump. Then, the iron-manganese hydroxide precipitate is washed repeatedly with sufficient water until the pH of the effluent is constant. This invention removes residual ions and alkali from the precipitate through washing. After washing, the precipitate is dried at a temperature of 80-105°C, preferably 85°C, 90°C, 95°C, or 100°C. This invention forms a biochar precursor loaded with iron-manganese hydroxide through a co-precipitation reaction.

[0029] After drying, the dried biochar precursor loaded with iron-manganese hydroxide is carbonized. As an optional implementation, the carbonization is carried out in a tube furnace. The carbonization temperature is 300-400℃, preferably 325℃, 350℃, or 375℃, and the carbonization time is 1.5-2.5 h, preferably 2 h. In this invention, carbonization is completed in an oxygen-free environment by introducing argon gas into the tube furnace. During the carbonization process, this invention can complete carbonization and improve the biochar yield at the specified carbonization temperature, converting the iron-manganese hydroxide biochar precursor into iron-manganese oxide to obtain modified corn straw biochar.

[0030] Based on the above-described method for preparing modified corn stalk biochar, this invention also provides modified corn stalk biochar obtained by the above-described method.

[0031] The present invention also provides a soil remediation agent, comprising the above-mentioned modified corn stalk biochar.

[0032] Based on the high-affinity adsorption and immobilization of sulfamethoxazole using modified corn straw biochar of this invention, this invention also provides the application of the above-mentioned modified corn straw biochar or the above-mentioned soil remediation agent in the adsorption or immobilization of sulfamethoxazole in soil. Complex interactions exist between different biomass precursors and target pollutants. This invention utilizes a mixed solution of ferric chloride and manganese chloride as a precursor, and co-precipitates it with corn straw biochar to prepare modified corn straw biochar, which can efficiently adsorb the pollutant sulfamethoxazole in soil. In this invention, the soil types include clay, loam, silty loam, and sandy loam; the concentration of sulfamethoxazole in the soil is 1~20 mg / L, preferably 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 12 mg / L, 14 mg / L, 16 mg / L, or 18 mg / L; the application rate of modified corn straw biochar is 0.5%~2% of the soil dry weight, preferably 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, or 1.8%; as an optional implementation, the modified corn straw biochar or soil remediation agent is evenly tilled and mixed into the soil surface layer, the depth of the soil surface layer being 0~20 cm, preferably 5 cm, 10 cm, 15 cm, or 20 cm. This invention achieves effective adsorption or fixation of sulfamethoxazole in the soil by uniformly tilling the soil to ensure that the modified corn straw biochar or soil remediation agent comes into full contact with the soil. The adsorption capacity can reach 7.43 mg / kg, which is 5 times higher than the adsorption performance. It also has good effect under different SMX pollution scenarios of 1~20 mg / L.

[0033] Based on the present invention, the modified corn stalk biochar is a biochar-based material. The present invention also provides the application of the above-mentioned modified corn stalk biochar or the above-mentioned soil remediation agent in improving soil aggregate structure and / or enhancing water and fertilizer retention capacity.

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the embodiments, but these should not be construed as limiting the scope of protection of this invention.

[0035] Unless otherwise specified, the materials, reagents, etc. used in the following examples are commercially available. Unless otherwise specified, they are generally used under conventional conditions or under conditions recommended by the company.

[0036] In the following embodiments, the preparation method of corn straw biochar includes the following steps: Collect corn stalks, wash them repeatedly with deionized water to remove the soil and impurities attached to the surface, place the washed corn stalks in an oven and dry them at 70℃ to a constant weight, then use a pulverizer to crush the dried stalks and sieve them through a 2 mm standard sieve to collect corn stalk powder with uniform particle size.

[0037] Corn stalk powder was added to a quartz boat and placed in a tube furnace. The furnace was purged with argon gas for 30 minutes to ensure an oxygen-free environment. The temperature was then increased to 500℃ at a rate of 10℃ / min and held at that temperature for 2 hours to carbonize the stalks into biochar. After pyrolysis, the furnace was allowed to cool naturally to room temperature under argon protection. The black solid product was removed and washed with deionized water to remove surface impurities until the conductivity of the washing solution remained constant. Finally, it was dried at 60℃ to obtain the corn stalk biochar.

[0038] Example 1 A method for preparing modified corn straw biochar: Corn stalk biochar was ground and passed through a 100-mesh sieve to obtain corn stalk biochar powder with uniform pore size. The corn stalk biochar powder was mixed with water at a mass ratio of 1:40 and treated at 25℃ and ultrasonic frequency of 40 kHz for 30 min to obtain a biochar suspension. The precursor was added to the biochar suspension and stirred continuously for 0.5 h. During stirring, 5 mol / L sodium hydroxide solution was slowly added dropwise to adjust the pH to 12. The precursor consisted of 0.003 mol / L ferric chloride solution and 0.006 mol / L manganese chloride solution; the molar ratio of the manganese chloride solution to the ferric chloride solution was 1:2.

[0039] After stirring, the iron-manganese hydroxide precipitate was obtained by vacuum filtration. The precipitate was then washed repeatedly with sufficient water until the pH of the effluent remained constant. After washing, the precipitate was dried at 90°C. Once dried, the dried biochar precursor loaded with iron-manganese hydroxide was placed in a ceramic or quartz boat and placed in a tube furnace for carbonization. The tube furnace was purged with argon gas for 30 min to ensure an oxygen-free environment. The temperature was increased to 350°C at a rate of 10°C / min and maintained at this temperature for 2 h.

[0040] Example 2 A method for preparing modified corn straw biochar: Corn stalk biochar was ground and passed through an 80-mesh sieve to obtain corn stalk biochar powder with uniform pore size. The corn stalk biochar powder was mixed with water at a mass ratio of 1:35 and treated at 20℃ and ultrasonic frequency of 40 kHz for 20 min to obtain a biochar suspension. The precursor was added to the biochar suspension and stirred continuously for 0.3 h. During stirring, 4 mol / L sodium hydroxide solution was slowly added dropwise to adjust the pH to 11. The precursor consisted of 0.002 mol / L ferric chloride solution and 0.006 mol / L manganese chloride solution; the molar ratio of the manganese chloride solution to the ferric chloride solution was 1:3.

[0041] After stirring, the iron-manganese hydroxide precipitate was obtained by vacuum filtration. The precipitate was then washed repeatedly with sufficient water until the pH of the effluent remained constant. After washing, the precipitate was dried at 80°C. Once dried, the dried biochar precursor loaded with iron-manganese hydroxide was placed in a ceramic or quartz boat and placed in a tube furnace for carbonization. The tube furnace was purged with argon gas for 30 min to ensure an oxygen-free environment. The temperature was increased to 400°C at a rate of 10°C / min and maintained at this temperature for 2 h.

[0042] Example 3 A method for preparing modified corn straw biochar: Corn stalk biochar was ground and passed through a 120-mesh sieve to obtain corn stalk biochar powder with uniform pore size. The corn stalk biochar powder was mixed with water at a mass ratio of 1:45 and treated at 30℃ and ultrasonic frequency of 40 kHz for 40 min to obtain a biochar suspension. The precursor was added to the biochar suspension and stirred continuously for 0.7 h. During stirring, 6 mol / L sodium hydroxide solution was slowly added dropwise to adjust the pH to 12. The precursor consisted of 0.004 mol / L ferric chloride solution and 0.010 mol / L manganese chloride solution; the molar ratio of the manganese chloride solution to the ferric chloride solution was 1:2.5.

[0043] After stirring, the ferromanganese hydroxide precipitate was obtained by vacuum filtration using a vacuum filtration pump. The precipitate was then washed repeatedly with sufficient water until the pH of the effluent was constant. After washing, the precipitate was dried at 105℃. After drying, the dried biochar precursor loaded with ferromanganese hydroxide was placed in a ceramic boat or quartz boat and placed in a tube furnace for carbonization. The tube furnace was purged with argon gas for 30 min to ensure an oxygen-free environment. The temperature was increased to 300℃ at a rate of 10℃ / min and maintained at this temperature for 1.5 h.

[0044] Experimental Example 1: Adsorption Kinetics Experiment In three conical flasks containing 0.01 mol / L CaCl2 solution, 10 mg / L SMX, and soil with 10% moisture content, 2% of the soil content of Example 1, unmodified corn straw biochar (as Comparative Example 2), and no biochar was added, with the latter serving as Comparative Example 1 (blank control). The flasks were then placed in a shaker at 25°C and 200 rpm. Samples were taken at adsorption times of 1 h, 2 h, 3 h, 4 h, 8 h, 12 h, 24 h, 36 h, and 48 h. After filtering through a 0.45 µm filter membrane, the SMX concentration was determined by high-performance liquid chromatography (HPLC). The results are shown below. Figure 1 As shown in the results, adsorption equilibrium was reached after 24 hours. At adsorption equilibrium, the adsorption capacities of SMX in Comparative Example 1, Comparative Example 2, and Example 1 were 1.48 mg / kg, 4.77 mg / kg, and 7.43 mg / kg, respectively. The results indicate that compared with soil without biochar application, both corn straw biochar and modified corn straw biochar significantly improved SMX adsorption, with adsorption capacities increasing by 3.3 times and 5.0 times, respectively. The modified corn straw biochar of this invention can efficiently adsorb or immobilize sulfamethoxazole in soil.

[0045] Experiment Example 2: Adsorption Isotherm Experiment In six conical flasks containing 0.01 mol / L CaCl2 solution and soil with 10% moisture content, SMX contaminants with initial concentrations of 1 mg / L, 2.5 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, and 20 mg / L were added, respectively. Then, 2% of the soil amount from Example 1 and unmodified corn straw biochar (as Comparative Example 2) were added, with the unmodified biochar serving as Comparative Example 1 (blank control). The flasks were then placed in a shaker at 25°C and 200 rpm. Samples were taken after 24 h of adsorption to reach adsorption equilibrium. The samples were filtered through a 0.45 µm filter membrane, and the SMX concentration was determined by high-performance liquid chromatography (HPLC). The results are shown below. Figure 2 As shown in the figure, the modified biochar exhibits good performance under different SMX pollution levels.

[0046] Experiment Example 3: Effect of Modified Corn Stalk Biochar on Antibiotic Pollution Adsorption in Different Soil Types In 24 conical flasks containing 0.01 mol / L CaCl2 solution and 10 mg / L SMX, four types of soil—clay, loam, silty loam, and sandy loam—with a moisture content of 10% were added, respectively. 0.5%, 1%, and 2% of Example 1 and unmodified corn straw biochar (as Comparative Example 2) were applied to each of the four soil types, respectively, with the unmodified soil serving as Comparative Example 1 (blank control). The flasks were then placed in a shaker at 25°C and 200 rpm. Samples were taken after 24 h of adsorption to reach adsorption equilibrium, filtered through a 0.45 µm filter, and the SMX concentration was determined by high-performance liquid chromatography (HPLC). Using Comparative Example 1 (soil without biochar) as a control, the fold increase in adsorption performance was calculated, and the experimental results are shown in Table 1.

[0047] Table 1. Effects of different soil types on the adsorption efficiency of modified corn straw biochar for SMX.

[0048] Experimental results show that in different types of soil (clay, loam, silty loam, and sandy loam), the corn straw biochar in Example 1 improved the adsorption performance of SMX. Furthermore, the SMX adsorption capacity continuously increased with the increase of the application rate of modified corn straw biochar. This indicates that the corn straw biochar prepared by this invention has wide applicability and can efficiently adsorb different types of soil. Comparative Example 2 also improved the adsorption of SMX, but the adsorption capacity of Example 1 was much higher than that of Comparative Example 2, proving that the introduction of iron-manganese composite oxides is the key to improving adsorption performance.

[0049] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing modified corn straw biochar, characterized in that, Includes the following steps: Corn stalk biochar powder was mixed with water to obtain a biochar suspension. The precursor was added to the biochar suspension, and the pH value was adjusted to 11-12 with sodium hydroxide solution. The precipitate of iron and manganese hydroxide was obtained by filtration, washing, drying and carbonization to obtain modified corn stalk biochar. The precursor includes a ferric chloride solution and a manganese chloride solution; The concentration of the manganese chloride solution is 0.002~0.004 mol / L, and the concentration of the ferric chloride solution is 0.004~0.010 mol / L.

2. The preparation method according to claim 1, characterized in that, The corn stalk biochar powder is pulverized to pass through an 80-120 mesh sieve, and the mass ratio of the corn stalk biochar powder to water is 1:35-45.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the manganese chloride solution to the ferric chloride solution is 1:1~3.

4. The preparation method according to claim 1, characterized in that, The rinsing continues until the pH of the effluent remains constant.

5. The preparation method according to claim 1, characterized in that, The drying temperature is 80~105℃.

6. The preparation method according to claim 1, characterized in that, The carbonization temperature is 300~400℃ and the time is 1.5~2.5 h.

7. Modified corn straw biochar obtained by the preparation method according to any one of claims 1 to 6.

8. A soil remediation agent, characterized in that, Including the modified corn stalk biochar as described in claim 7.

9. The application of the modified corn straw biochar of claim 7 or the soil remediation agent of claim 8 in the adsorption or immobilization of sulfamethoxazole in soil, characterized in that, The soil types include clay, loam, silty loam, and sandy loam.

10. The application of the modified corn straw biochar of claim 7 or the soil remediation agent of claim 8 in improving soil aggregate structure and / or enhancing water and fertilizer retention capacity.

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