Multi-element co-modified carbon material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of water and soil herbicide residue pollution treatment, and relates to a multi-element co-modified carbon material as well as a preparation method and application thereof. The multi-element co-modified carbon material is prepared from the following raw materials in parts by weight: 8 to 15 parts of water-soluble trivalent ferric salt, 7 to 14 parts of thiourea and 6 to 14 parts of reed straw. The water-soluble ferric salt is ferric chloride, ferric nitrate or ferric sulfate; according to the multi-element co-modified carbon material, water-soluble ferric salt and thiourea serve as modifiers, reed straw biochar is modified through a one-step hydrothermal method, and the multi-element co-modified carbon material is obtained. The material provided by the invention can efficiently degrade quinclorac in water and soil, has good magnetism and stability, is easy to recover, and can repair plants damaged by soil herbicide residues.

Description

Technical Field

[0001] This invention belongs to the field of water and soil herbicide residue pollution control technology, and relates to a multi-element co-modified carbon material, its preparation method and application. Background Technology

[0002] Herbicides play a vital role in controlling weeds and ensuring crop yields. However, most herbicides degrade slowly in the field, have long residual periods, and can harm aquatic plants and animals if they run off into water bodies. Residue in the soil can also cause phytotoxicity to subsequent sensitive crops. For example, in areas where quinclorac acid is applied at the recommended dosage, several crops, including solanaceous and leguminous plants, cannot be planted within a year. In tobacco-rice rotation areas, the use of quinclorac acid-containing herbicides in the preceding rice field can easily cause phytotoxicity to the subsequent tobacco crop, leading to curled leaves, stunted plants, and severely impacting the yield and quality of flue-cured tobacco. How to quickly and effectively remove quinclorac acid herbicide residues and reduce their harm to the ecological environment is a pressing issue. Currently, methods for removing herbicide residues from the environment mainly include physical, chemical, and biological methods. Physical methods primarily involve adsorbing herbicide residues onto the surface of an adsorbent using physical means. While simple to operate, this method fails to completely remove pollutants from the environment, and the pollutants adhering to the adsorbent may desorb, causing secondary pollution. Biological methods typically utilize the metabolic activities of microorganisms to decompose organic pollutants. Although low-cost, this method suffers from difficulties in strain selection and low degradation efficiency. Chemical methods remove organic pollutants through oxidation reactions, most commonly using catalytic persulfate advanced oxidation technology. Compared to physical and biological methods, this method offers advantages such as thorough pollutant removal and high degradation efficiency.

[0003] However, advanced oxidation technologies based on persulfates typically require the initial activation of the persulfate. Common activation methods include thermal activation, microwave activation, ultrasonic activation, and transition metal activation. The first three methods consume significant energy, limiting their large-scale application. Transition metals, especially iron-based materials, are commonly used persulfate activation materials due to their abundant reserves, readily available raw materials, and high catalytic efficiency. Among these, magnetic iron-based materials exhibit high catalytic activity and recyclability. However, pure magnetic iron-based materials are prone to agglomeration, usually requiring loading onto other supports to reduce aggregation. Clay minerals and carbon-based materials are common choices. Carbon-based materials derived from agricultural waste offer significant advantages, including a wide range of raw material sources, low cost, simple preparation, and environmental friendliness.

[0004] The prior art CN116571276A discloses the preparation of a straw organic copper pesticide degradation material, the steps of which are as follows: (1) Straw oxidation treatment: Add 5-20% hydrogen peroxide solution and 10-20 times the straw weight of pure water to straw powder with a particle size range of 0.1mm-5mm, adjust the pH of the reaction solution to 10-12, stir evenly, then add 0.5-2% urea by weight of straw, stir quickly, and control the temperature at 40-60℃. After ultrasonic reaction for 2-5 hours, filter, wash with pure water 2-3 times, and dry thoroughly at 60-70℃ to obtain oxidized straw powder; wherein, the concentration of hydrogen peroxide solution is 30-40 wt.%; (2) Preparation of straw organic copper composite material: Add 2-5 times the mass of straw of water-containing N,N dimethylformamide solution and 2-5 times the mass of straw of anhydrous ethanol to the oxidized straw powder in step (1), the volume ratio of the two liquids is controlled at 1:1, and stir thoroughly. Mix thoroughly and sonicate at room temperature for 5-10 minutes. Add 10-20% (by weight of straw) of 1,3,5-benzenetricarboxylic acid and 0.1-0.5% (by weight of straw) of acetic anhydride, mix well, and sonicate at 30-40℃ for 20-60 minutes. Add 15-30% (by weight of straw) of copper nitrate trihydrate solid and 0.1-2% (by weight of straw) of silica solid, mix thoroughly, and sonicate at room temperature for 10-15 minutes. Then seal and place in a forced-air drying oven with an air velocity of 5. The reaction mixture (0-80%) is reacted at 80-150℃ for 5-20 hours. After cooling to room temperature, it is washed 3-5 times sequentially with an aqueous N,N-dimethylformamide solution and pure water. The synthesized material is then placed in a vacuum drying oven and dried thoroughly at 60-80℃ for 15-24 hours to obtain a solid powder of straw-based organic copper pesticide degradation material. This powder is then packaged in sealed bags and stored at room temperature for later use. The concentration of the aqueous N,N-dimethylformamide solution is 40-80 wt.%. This method improves the adsorption capacity of straw through oxidation treatment, and prepares straw-based organic copper composite materials based on a one-step hydrothermal synthesis method. However, this existing technology requires pretreatment of the straw with reagents such as hydrogen peroxide and urea under specific pH conditions, followed by the addition of various organic reagents for composite material preparation. The preparation conditions require strict control of acidity, which can cause secondary pollution to the environment during application. When used for soil remediation, this invention requires the preparation of straw-organic copper and persulfate compound granules using a three-dimensional rotary granulation method. These granules are then applied to ditches around farmland and filled with soil to prevent the spread of herbicides and other pesticides. This process is time-consuming and labor-intensive, and its effectiveness in remediating crop damage caused by pollutant residues within farmland needs further improvement.

[0005] Existing technology CN118527130A relates to a boron-doped biochar for promoting tobacco growth, its preparation method, and a catalytic system. The preparation method of the boron-doped biochar includes adding a boron source to water and heating it to dissolve; then adding a carbon source and stirring until a mixture is obtained; the mixture is heated to dryness under stirring to obtain a concentrate; the concentrate is dried and calcined to obtain boron-doped biochar. The carbon source includes at least one of waste tea leaves, fruit peels, fruit shells, tobacco stalks, and reed stalks. The catalytic system includes adding persulfate to the boron-doped biochar. However, this invention requires pretreatment of the biomass and modifiers before pyrolysis at high temperatures (550-650, 700℃), resulting in high energy consumption. Furthermore, this invention treats water containing dichloroquinoline acid through its degradation system before using it to irrigate tobacco. However, this catalytic system is not effective in remediating tobacco and soil that has already suffered pesticide damage.

[0006] The prior art CN118598373A discloses a preparation method and application of a remediation agent for water and soil polluted by methimazole herbicide. The preparation method includes adding corn stalk powder to an aqueous solution containing ferric chloride hexahydrate, stirring and separating, and then drying the solidified material to obtain a composite material precursor; using a carbothermal reduction method, the composite material precursor is used to reduce ferric iron by hydrogen or carbon monoxide generated under high temperature and oxygen-deficient conditions, so that the generated nano-zero ferric iron is loaded on the surface of biochar to obtain nano-zero ferric iron modified biochar; the fermentation broth of degrading bacteria is fixed on the nano-zero ferric iron modified biochar by physical adsorption, and then freeze-dried to obtain the remediation agent for water and soil polluted by methimazole herbicide. However, this invention requires pretreatment of biomass and modifiers before pyrolysis at high temperatures (550-650, 700℃), resulting in high energy consumption. Furthermore, it necessitates the introduction of microbial degrading bacteria, which are unstable and susceptible to environmental factors. These bacteria also exhibit specificity, with different bacteria degrading different types of pollutants. Moreover, this invention primarily investigates the degradation of pesticide residues by adding the remediation agent to the soil, and cannot degrade quinclorac herbicides. Therefore, the remediation effect is poor for tobacco plants already showing phytotoxicity.

[0007] Existing technology CN119818896A discloses a soil pesticide residue degrading agent and its application. This soil pesticide residue degrading agent comprises the following components: montmorillonite-hydrothermal carbon composite material and persulfate. The montmorillonite-hydrothermal carbon composite material is prepared by hydrothermal reaction using montmorillonite and a biomass carbon source as raw materials. The biomass carbon source is at least one of sucrose and starch. The hydrothermal reaction temperature is 160-220℃; and / or, the hydrothermal reaction time is more than 5 hours. Montmorillonite (MMT) is acidified with dilute hydrochloric acid for 24 hours, then repeatedly washed with ultrapure water until the pH value of the acidified montmorillonite (MMT) is near neutral. It is then dried in an oven at 105℃ for 24 hours, ground, and passed through a 100-mesh sieve before use. However, this invention requires first treating the montmorillonite mineral with acid, a process that is time-consuming (24 hours of acidification followed by 24 hours of drying) and cumbersome. Then, it is prepared by hydrothermal treatment with sucrose or starch, resulting in high costs and making it unsuitable for large-scale use. Furthermore, this invention requires incorporating the mineral into the soil through tilling 3-7 days after the previous crop harvest and before the next crop sowing, with a tilling depth of 10-20 cm, making the operation cumbersome and time-consuming.

[0008] The prior art CN116273070A discloses a bimetallic sulfide catalyst based on osmanthus leaf biomass, its preparation method, and its application. The preparation method of the catalyst includes the following steps: (1) roasting osmanthus leaves to obtain a biochar precursor; (2) dispersing the biochar precursor, sodium molybdate, thiourea, and ferric chloride evenly in water to obtain a mixed system A; (3) placing the mixed system A in a closed reactor for hydrothermal reaction to obtain a mixed system B; (4) drying the mixed system B to obtain the catalyst. The catalyst can effectively utilize the energy of harmful substances to purify water quality under the induction of trace peroxides, with high catalytic efficiency, wide pH response range, and cheap and readily available raw materials, making it easy to promote and apply. However, the molybdenum used in this invention is an emerging pollutant. Excessive intake of molybdenum by animals can lead to anemia, fertility and growth retardation, and premature death, resulting in the risk of secondary environmental pollution. The biochar prepared from osmanthus leaves contains less nitrogen, phosphorus, potassium, and other nutrients, making it ineffective for soil remediation. Summary of the Invention

[0009] The purpose of this invention is to provide a multi-element co-modified carbon material that can degrade dichloroquinoline acid in soil, its preparation method, and its application.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A multi-element co-modified carbon material comprises the following raw materials in parts by weight: 8-15 parts of water-soluble trivalent iron salt, 7-14 parts of thiourea, and 6-14 parts of reed straw.

[0012] The water-soluble ferric salt is ferric chloride, ferric nitrate, or ferric sulfate;

[0013] The multi-element co-modified carbon material is obtained by modifying reed straw biochar with water-soluble trivalent iron salt and thiourea as modifiers through a one-step hydrothermal method.

[0014] This invention utilizes agricultural waste reed straw as raw material and water-soluble ferric salts and thiourea as modifiers to prepare a novel modified biochar material (Fe / SN-HC) via a one-step hydrothermal method. This material can efficiently activate ammonium persulfate (APS) to degrade quinclorac acid residues in water and soil. This system not only repairs quinclorac acid residue damage in tobacco but also promotes tobacco growth.

[0015] Potassium is the most important mineral nutrient in tobacco, and its content in tobacco leaves is a crucial factor affecting leaf quality. Reeds, as a gramineous crop, are rich in nitrogen, phosphorus, potassium, and other macronutrients. 80% of the potassium absorbed by reeds is found in their straw, primarily in ionic form, allowing for rapid release into the soil. Applying reed straw biochar to tobacco-growing soil can, to some extent, increase soil nutrient content and improve potassium accumulation and yield in tobacco plants. Before leaves fall, nutrient transfer occurs; nitrogen, phosphorus, and potassium in the leaves are transferred to other plant tissues, leading to a significant decrease in nutrient content within the leaves.

[0016] According to embodiments of the present invention, the present invention can be further optimized, and the optimized technical solution is as follows:

[0017] Based on the same inventive concept, this invention also claims protection for a method for preparing the multi-element co-modified carbon material, comprising the following steps:

[0018] Water-soluble ferric salts and thiourea were dissolved in a solvent, and then reed straw was added and mixed evenly. A hydrothermal reaction was carried out, and the resulting product was washed, dried, ground, and sieved to obtain the multi-element co-modified carbon material.

[0019] In one preferred embodiment, the reed stalks are dried, crushed, and sieved powder particles with a sieve mesh size of 20-40.

[0020] In one preferred embodiment, the hydrothermal reaction time is 16-24 hours, preferably 17-24 hours, and more preferably 17-20 hours.

[0021] In one preferred embodiment, the hydrothermal reaction temperature is 160-220°C.

[0022] In one preferred embodiment, the washing involves washing several times with deionized water and ethanol until neutral.

[0023] In one preferred embodiment, the drying temperature is 70-90°C.

[0024] In one preferred embodiment, the sieve opening is 80-100 mesh.

[0025] Based on the same inventive concept, the present invention also claims protection for the application of the multi-element co-modified carbon material in the degradation of dichloroquinoline acid.

[0026] Based on the same inventive concept, this invention also claims protection for the application of the multi-element co-modified carbon material in the remediation of plants damaged by dichloroquinoline acid.

[0027] In one preferred embodiment, the plant is tobacco.

[0028] In one preferred embodiment, the amount of the multi-element co-modified carbon material is 0.1-0.3 g / L.

[0029] In one preferred embodiment, the pH value of the system for degrading dichloroquinoline acid by multi-element co-modified carbon material is 2-9.

[0030] In one preferred embodiment, the temperature of the system for degrading dichloroquinoline acid by the multi-element co-modified carbon material is 10-40°C, preferably 15-35°C.

[0031] Based on the same inventive concept, the present invention also claims a catalytic system comprising adding persulfate to the above-mentioned multi-element co-modified carbon material.

[0032] In one preferred embodiment, the mass ratio of the multi-element co-modified carbon material to persulfate is 2:(3.4-6.9); preferably 2:4.56.

[0033] In one preferred embodiment, the persulfate includes sodium persulfate, potassium persulfate, and ammonium persulfate.

[0034] Based on the same inventive concept, the present invention also claims protection for the application of the catalytic system in the degradation of dichloroquinoline acid in water and soil.

[0035] Based on the same inventive concept, this invention also claims protection for the application of the catalytic system in the remediation of plants damaged by dichloroquinoline.

[0036] In one preferred embodiment, the plant is tobacco.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] This invention utilizes agricultural waste reed stalks as raw material and ferric chloride and thiourea as modifiers to prepare a novel modified biochar material (Fe / SN-HC) via a one-step hydrothermal method. This material can efficiently activate ammonium persulfate (APS) to degrade dichloroquinoline acid residues in water and soil. The material is magnetic, exhibits good stability, and is easily recyclable. Furthermore, since the catalytic degradation system of this invention ultimately mineralizes into inorganic carbon dioxide and water, and also contains essential nutrients for plants such as C and N, this catalytic degradation system, when used for root irrigation treatment of tobacco plants damaged by herbicide residues in the soil, will effectively repair the herbicide damage. Attached Figure Description

[0039] Figure 1 These are scanning electron microscope (SEM) images and elemental energy dispersive spectroscopy (EDS) images of different modified materials; where (a) is the SEM image of HC, (b) is the SEM image of Fe-HC, (c) is the SEM image of SN-HC, (d) is the SEM image of Fe / SN-HC, and (e) is the elemental energy dispersive spectroscopy image.

[0040] Figure 2 These are X-ray diffraction (XRD) patterns of different modified materials.

[0041] Figure 3 This is a line graph showing the effect of APS concentration on the degradation of dichloroquinoline acid.

[0042] Figure 4 This is a line graph showing the effect of the catalytic degradation system on the degradation efficiency of dichloroquinoline acid under different pH conditions.

[0043] Figure 5 This is a line graph showing the effect of coexisting anions on the removal efficiency of dichloroquinoline acid.

[0044] Figure 6 This is a line graph showing the effect of the concentration of different pollutants, such as dichloroquinoline, on the removal efficiency.

[0045] Figure 7 This is a line graph showing the effect of reaction temperature on the removal efficiency.

[0046] Figure 8 It is the hysteresis regression line after repeated use of Fe / SN-HC material.

[0047] Figure 9 These are XPS spectra before and after the Fe / SN-HC reaction; (a) is the overall spectrum; (b) is Fe 2p; (c) is S 2p; and (d) is N 1s.

[0048] Figure 10The values ​​are ESR signals of the catalytic degradation system; (a) represents the ESR signals of sulfate radicals and hydroxyl radicals at different times in the Fe / SN-HC@APS system; (b) represents the ESR signals of superoxide radicals at different times in the Fe / SN-HC@APS system; and (c) represents the ESR signals of sulfur singlet oxygen at different times in the Fe / SN-HC@APS system.

[0049] Figure 11 This is a schematic diagram of the possible degradation pathways of dichloroquinoline acid.

[0050] Figure 12 It is the effect of the catalytic degradation system on the repair of dichloroquinoline acid damage in tobacco. Detailed Implementation

[0051] This invention is not limited to the specific embodiments listed below. Those skilled in the art can implement this invention using various other specific embodiments based on the content disclosed herein. Any modifications or alterations made to the design structure and concept of this invention fall within the protection scope of this invention. It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0052] Example 1

[0053] Comparison of the degradation performance of dichloroquinoline acid by different activated ammonium persulfate (APS) materials

[0054] 10.81 g of ferric chloride (FeCl3·6H2O) and 9.13 g of thiourea were weighed and added to 100 mL of deionized water. The mixture was magnetically stirred until completely dissolved. Then, 10.00 g of dried, pulverized, and sieved (20 mesh) waste reed straw powder was added. The mixture was magnetically stirred for 30 min at room temperature until homogeneous. The mixture was then transferred to a hydrothermal reactor and hydrothermally heated at 220 °C for 24 h. After the hydrothermal product had completely cooled, it was washed several times with deionized water and ethanol until neutral. After complete drying at 80 °C, it was ground and sieved through a 100-mesh sieve. The resulting hydrothermal carbon was named Fe / SN-HC. Simultaneously, materials modified with a single modifier (ferric chloride or thiourea) were prepared using the same steps. The unmodified material, the material modified with ferric chloride alone, and the material modified with thiourea alone were named HC, Fe-HC, and SN-HC, respectively.

[0055] Scanning electron microscope (SEM) images and Fe / SN-HC elemental energy dispersive spectroscopy (EDS) spectra of different modified materials are as follows: Figure 1As shown in the figure, scanning electron microscopy (SEM) images were used to analyze the microstructure of the material surface. (a) and (d) represent HC, Fe-HC, SN-HC, and Fe / SN-HC, respectively. The unmodified biochar (a) has a smooth and flat surface. In contrast, the iron-modified biochar (b) exhibits a porous, aggregated morphology. The thiourea-modified biochar (c) shows more carbon spheres of more uniform size and shape, and a richer pore structure. The iron and thiourea co-modified biochar (d) has a loose and porous surface, while also avoiding the aggregation of magnetic particles. These changes are beneficial for increasing the contact area between the material and oxidants and pollutants, promoting catalytic degradation reactions. According to the elemental energy dispersive spectroscopy (EDS) diagram (e), Fe, S, and N are uniformly distributed on the material surface, indicating that both modifiers were successfully incorporated into the biochar.

[0056] XRD patterns of different modified materials, as shown below Figure 2 As shown in the figure, XRD patterns are used to analyze the phase composition of different materials. The figure shows that Fe appears in the Fe / SN-HC spectrum. 0 The discovery of three new phases—Fe3S4 and FeS2—further demonstrates that iron and thiourea have been successfully incorporated into biochar, and that a reaction has occurred between the two modifiers. The formation of these new phases is a key reason for the significant enhancement in the material's ability to remove dichloroquinoline acid.

[0057] The degradation performance of these four materials by dichloroquinoline acid was compared as follows:

[0058] Accurately measure 50 mL of dichloroquinoline acid solution (10 mg·L⁻¹). -1 In a 100 mL Erlenmeyer flask, add 0.02 g of HC, Fe-HC, SN-HC, and Fe / SN-HC respectively, and then add the same concentration of ammonium persulfate (2 mmol·L⁻¹). -1 The conical flask was placed in a constant temperature shaker and the reaction was carried out at 25℃ and 150 rpm. At 10, 30, 60, 90, 120 and 180 min, 1.0 mL of the reaction solution was taken and added to 1.0 mL of methanol solution to terminate the reaction. The solution was filtered through a 0.45 μm filter membrane, and the concentration of dichloroquinoline acid remaining in the solution was determined by high performance liquid chromatography. The removal rate of dichloroquinoline acid in different systems was calculated and is shown in Table 1.

[0059] The results showed that the removal rate of the unmodified material was only 1.49%, while the removal rate of the co-modified material Fe / SN-HC was as high as 98.88%, exceeding the sum of the removal effects of Fe-HC and SN-HC modified alone, indicating that there is a synergistic effect between the two modifiers, thiourea and ferric chloride.

[0060] Comparative Example 1

[0061] Based on Example 1, biomass was prepared by replacing reed straw with an equal amount of osmanthus leaves using the same method as in Example 1, and other materials were the same as in Example 1.

[0062] The properties of the prepared materials were tested, and the results are shown in Table 2.

[0063] As shown in Table 2, the unmodified osmanthus leaf biochar (HC2) exhibited a degradation rate of only 0.63% for dichloroquinoline acid (APS) catalyzed by APS, while the osmanthus leaf biochar co-modified with ferric chloride and thiourea (Fe / SN-HC2) showed the highest degradation rate (56.48%). Compared with Table 1, it is evident that the catalytic degradation performance of different biochars made from osmanthus leaves is inferior to that of biochar made from reed straw.

[0064] Example 2

[0065] Effect of hydrothermal time during preparation on the catalytic degradation performance of the material

[0066] Based on Example 1, the hydrothermal time at 220℃ was adjusted to 4h, 8h, 12h and 17h, respectively, to prepare Fe / SN-HC with hydrothermal times of 4h, 8h, 12h and 17h.

[0067] Fe / SN-HC solutions prepared with hydrothermal times of 4h, 8h, 12h, and 17h were used to activate APS to degrade dichloroquinoline acid. The degradation rate constants of dichloroquinoline acid in different systems were calculated, and the results are shown in Table 3.

[0068] The results showed that the catalytic effect of several materials improved with increasing hydrothermal time. At hydrothermal times of 17 h and 24 h, the degradation rate of dichloroquinoline acid was the fastest, with no significant difference between the two. With increasing hydrothermal time, the proportion of Fe3S4 in the material increased, resulting in better catalytic effect, improved uniformity and dispersibility of the prepared material, and better contact between the material and the oxidant and pollutants. Therefore, a hydrothermal time of 17 h–24 h was selected for material preparation.

[0069] Example 3

[0070] Effect of different Fe / SN-HC dosages on the degradation of dichloroquinoline acid by activated ammonium persulfate

[0071] Accurately measure 50 mL of dichloroquinoline acid solution (10 mg·L⁻¹). -1 In a 100 mL Erlenmeyer flask, at an APS concentration of 0.5 mmol·L⁻¹ -1Under certain conditions, different masses of Fe / SN-HC were added to the system, resulting in concentrations of 0, 0.05, 0.1, 0.2, and 0.3 g·L⁻¹, respectively. -1 The residual concentration of dichloroquinoline acid in the system was measured at 10, 30, 60, 90, 120 and 180 min of reaction, and the results are shown in Table 4.

[0072] The results showed that the reaction rate differed with different Fe / SN-HC dosages. When the Fe / SN-HC dosage increased from 0.05 g·L⁻¹, the reaction rate decreased. -1 Increase to 0.2 g·L -1 Due to the increase in reactive sites, the removal rate increased significantly; further increasing the concentration to 0.3 g·L⁻¹ resulted in a significantly faster removal rate. -1 At that time, due to excess Fe in the system 2+ It has a quenching effect on sulfate free radicals in the system, which is detrimental to the reaction and actually slows down the degradation rate. Therefore, the amount of Fe / SN-HC used should be selected as 0.1-0.3 g·L. -1 0.2 g·L is preferred. -1 .

[0073] Example 4

[0074] With the Fe / SN-HC dosage kept constant, the effect of different amounts of APS on the degradation of dichloroquinoline acid was investigated.

[0075] Accurately measure 50 mL of dichloroquinoline acid solution (10 mg·L⁻¹). -1 In a 100 mL Erlenmeyer flask, the Fe / SN-HC dosage was 0.2 g·L⁻¹. -1 Under the specified conditions, different amounts of APS were added to the system to achieve concentrations of 0.25, 0.5, 1, and 2 mmol·L⁻¹. -1 The residual concentration of dichloroquinoline acid in the system was measured at 10, 30, 60, 90, 120, and 180 min of reaction. The results are as follows: Figure 3 As shown in Table 5.

[0076] The results showed that the degradation rate varied significantly with different concentrations of APS. The degradation rate of quinclorac acid increased with increasing APS concentration; for example, from 0.25 mmol / L to 2 mmol / L, the degradation rate decreased from 0.0186 min / min. -1 Increased to 0.2054 min -1 As the amount of oxidant increases, more active substances can be generated, which is beneficial to the degradation reaction and thus increases the degradation rate of dichloroquinoline acid.

[0077] Comparative Example 2

[0078] Based on Example 1, 10.0 g of waste reed straw, sodium zeolite, 9.13 g of thiourea and 10.81 g of ferric chloride (FeCl3·6H2O) were added and dispersed evenly in water to obtain a mixed system, and then a hydrothermal reaction was carried out, the same as in Example 1.

[0079] The preparation method of sodium-type zeolite is as follows: prepare a 1.0 mol / L NaCl solution, add 32.4 g of zeolite to the solution at a mass ratio of 1:10, place the solution in a constant temperature water bath at 30℃, stir mechanically for 2.5 hours, then wash with distilled water, filter, dry and grind to obtain sodium-type zeolite.

[0080] Other materials are the same as in Example 1.

[0081] The prepared material was subjected to a dichloroquinoline acid removal rate experiment, following the same procedure as in Example 1. The results showed that the degradation rate of dichloroquinoline acid by the activated APS of this material was only 70.65%, which was much lower than the degradation rate of dichloroquinoline acid by Fe / SN-HC activated APS (98.88%). This indicates that the addition of zeolite during preparation affects the catalytic performance of the composite material, which is not conducive to the activation of APS, thus leading to a decrease in the degradation rate.

[0082] Comparative Example 3

[0083] Based on the Fe / SN-HC material in Example 1, 10.0 g of waste reed straw was first calcined in a high-temperature oxygen-limited (700℃) nitrogen atmosphere for 2 h to obtain a biochar precursor. This precursor was then dispersed evenly in water with 9.13 g of thiourea and 10.81 g of ferric chloride (FeCl3·6H2O) to obtain a mixed system. The preparation method and other materials were the same as in Example 1.

[0084] The dichloroquinoline acid removal rate of the prepared material was tested, and the steps were the same as in Example 1. The results are shown in Table 6 below.

[0085] The unmodified material and the composite modified material were named HC3 and Fe / SN-HC3, respectively.

[0086] The results showed that pure biochar (HC3) catalyzed the degradation rate of dichloroquinoline acid by APS of only 6.63%, while biochar co-modified with thiourea (Fe / SN-HC3) had the highest degradation rate of dichloroquinoline acid (72.19%). This may be because biochar generated under high temperature conditions is not conducive to the formation of catalytic active sites with thiourea and ferric chloride in the hydrothermal process.

[0087] Comparative Example 4

[0088] Based on the Fe / SN-HC material in Example 1, 10.0 g of waste reed straw was first calcined at 70°C in a nitrogen atmosphere for 2 h to obtain a biochar precursor. This precursor was then dispersed evenly in water with 10.81 g of thiourea and ferric chloride (FeCl3·6H2O) to obtain a mixed system. The molar ratio of sulfur in thiourea to iron in ferric chloride was 200:1. The mixed system was placed in a closed reactor and subjected to a hydrothermal reaction at 200°C for at least 12 hours to obtain a mixture. After washing, the mixture was dried at 80°C for 12 h to obtain the catalyst.

[0089] The prepared catalyst was subjected to a dichloroquinoline acid removal rate experiment, following the same procedure as in Example 1. The results showed that the catalyst achieved a dichloroquinoline acid catalytic degradation rate of only 47.82%.

[0090] Comparative Example 5

[0091] Based on the Fe / SN-HC material in Example 1, the hydrothermal reaction vessel was changed from 220°C for 24 hours to heating the mixture under stirring conditions (heating temperature of 70°C) to dryness, and a concentrate was obtained. Then the concentrate was dried (drying temperature of 60°C for 24 hours) and calcined in a high-temperature nitrogen atmosphere (calcination temperature of 600°C for 2 hours).

[0092] Other preparation methods are the same as in Example 1, and other materials are the same as in Example 1.

[0093] The dichloroquinoline acid removal rate of the prepared material was tested, and the steps were the same as in Example 1. The results are shown in Table 7.

[0094] The unmodified material and the composite modified material were named HC4 and Fe / SN-HC4, respectively.

[0095] The results showed that pure biochar (HC4) catalyzed a low degradation rate of dichloroquinoline acid (APS) by hydroxylamine (APS), while biochar modified with ferric chloride (Fe-HC4) and thiourea (Fe / SN-HC4) catalyzed a degradation rate of 25.32% for APS. This indicates that high temperature conditions are not conducive to the formation of catalytically active functional groups of thiourea on the straw surface, while high temperature conditions are conducive to the formation of catalytically active species by iron, which enhances the catalytic activity of biochar for APS and thus improves the degradation rate of dichloroquinoline acid.

[0096] Example 5

[0097] The effects of different initial pH, coexisting anions, pollutant concentrations, and reaction temperatures on the removal efficiency of dichloroquinoline acid were investigated.

[0098] The Fe / SN-HC dosage was 0.27 g·L. -1 The APS concentration was 2 mmol·L⁻¹ -1 Under these conditions, batch experiments were conducted to investigate the initial pH (2.38, 4.23, 7.36, 8.74, 10.66) and coexisting anions (Cl-). - HCO3 - SO4 2- NO3 - The effects of the concentrations (5, 10, 20, 30 ppm) and reaction temperatures (15, 25, 35 °C) of the pollutant dichloroquinoline acid on the removal efficiency were investigated. Samples were taken at 5, 10, 20, 30, and 60 min of reaction to determine the residual concentration of dichloroquinoline acid in the system. The removal rates of dichloroquinoline acid in each system after 60 min of reaction are shown in Table 8. Figure 4 , Figure 5 , Figure 6 , Figure 7 .

[0099] The results showed that QC could be completely removed within the acidic to weakly alkaline range (pH = 2.38~8.74), but there was virtually no removal effect when the pH reached 10.66. This is because, on the one hand, an alkaline environment is not conducive to the formation of QC on the material surface. · OH, and SO4 ·– It will also turn into · The redox potential of OH- decreases further in an alkaline environment, leading to a decrease in the overall potential of the system. On the other hand, Fe(OH)2 may form in an alkaline environment. 2+ and K sp The very low Fe(OH)3 precipitates may adhere to the material surface, preventing sufficient contact between the material and oxidants and contaminants, thus hindering the degradation reaction.

[0100] The coexisting anions, pollutant concentrations, and reaction temperature have virtually no effect on the removal efficiency of dichloroquinoline acid, which to some extent indicates that this reaction system has universality.

[0101] Example 6

[0102] Examine the material's stability and magnetism

[0103] When the catalyst dosage is 0.2 g·L -1 The oxidant concentration was 2 mmol·L⁻¹ -1Under the reaction conditions described in Example 1, the recycling performance of the Fe / SN-HC+APS catalytic degradation system was investigated. The material after degradation was recovered using a magnet, washed several times with deionized water and anhydrous ethanol until neutral, dried at 80°C, and then used for the next round of experiments. A total of three rounds of recycling experiments were conducted. The iron dissolution in the system during each round of recycling was determined using the bispyridine colorimetric method. The removal rate of dichloroquinoline acid in the three rounds of recycling experiments is shown in Table 9. After recycling, the material still retains its magnetic properties, facilitating recovery; its hysteresis regression line is shown in Table 9. Figure 8 As shown.

[0104] The results showed that the material had excellent recycling performance. After three uses, the activated APS still maintained a degradation rate of over 92% for dichloroquinoline acid, and the iron leaching amount was 0.22 mg / L, which was lower than the limit value for centralized drinking water (0.3 mg / L). This indicates that the material not only has good stability, but also is easy to recycle after use due to its magnetic properties.

[0105] like Figure 9 As shown, compared with before the reaction, Fe 0 The characteristic peaks disappeared, the Fe(III) content decreased from 34.86% to 27.32%, and the Fe(II) content increased from 55.04% to 72.68%. According to charge conservation, the overall oxidation state of the iron system increased, indicating that iron was oxidized during the activation of APS. After the reaction, S... 2- and S n 2- / S 0 The contents increased from 9.65% and 56.06% to 10.70% and 58.70%, respectively, SO4 2- The content decreased from 34.29% to 30.60%. S showed slight changes in different valence states, indicating that S participated in the redox process. After the reaction, the N content in graphite decreased from 92.53% to 50.88%, the characteristic peak of pyridine N disappeared, and 49.12% pyrrole N was generated, indicating that the N atom is also an important reaction site. The possible reaction mechanism is as follows:

[0106] .

[0107] .

[0108] .

[0109] .

[0110] .

[0111] .

[0112] .

[0113] .

[0114] Example 7

[0115] Investigating the types of active substances produced by the activation of ammonium persulfate with modified carbon materials

[0116] 5,5-Dimethyl-pyrrolidone-nitrogen oxides (DMPO) were used as SO4. ·- •OH and O2 ·- Tetramethylpiperidone (TEMP) is used as a free radical scavenger. 1 O2 non-radical scavengers were used, and the presence of each active substance was determined by electron paramagnetic resonance (EPR) technology through the hyperfine coupling interaction between these active substances and DMPO and TEMP. The Fe / SN-HC material and APS from Example 1 were sent separately to an analytical company for analysis of their reactive substances. The presence and characteristics of the active substances (radicals and non-radicals) were analyzed by detecting the spin resonance signal of unpaired electrons in the samples using electron paramagnetic resonance spectroscopy.

[0117] The measurement results are as follows Figure 10 As shown, SO4 was detected in the system. ·- •OH 1 O2 and O2 ·- The characteristic signal indicates that dichloroquinoline acid may react with the aforementioned active substances in this catalytic degradation system to generate various degradation intermediates, and ultimately decompose into small molecules such as water and carbon dioxide. Possible degradation pathways include... Figure 11 As shown.

[0118] Example 8

[0119] Effects of catalyst dosage, APS dosage, water-to-soil ratio, and reaction temperature on the degradation of dichloroquinoline acid in soil

[0120] Add dichloroquinoline acid to the soil to a concentration of 20 mg / L. -1This study investigated the effects of Fe / SN-HC+APS catalyst dosage (0%, 1%, 2%, 3%), ammonium persulfate dosage (0%, 1%, 2%, 3%), soil-water ratio (1:1, 2.5:1, 4:1), and reaction temperature (15℃, 25℃, 35℃) on the degradation of dichloroquinoline acid in soil under the conditions of Example 1. After a 24-hour shaking reaction at 180 rpm, residual dichloroquinoline acid in the soil was extracted using the QuEChERS method: 10 mL of acetonitrile solution (containing 1% formic acid) was added to the reaction system, vortexed for 10 min, 2 g of sodium chloride was added, vortexed for 5 min, and centrifuged at 8000 rpm for 5 min. After standing for 10 min, 2.00 mL of the supernatant was added to a centrifuge tube containing 20 mg of C18, vortexed for 1 min, filtered through a 0.45 μm organic filter membrane, and the residual dichloroquinoline acid was determined by high-performance liquid chromatography. The removal rates of dichloroquinoline acid in the soil under different reaction conditions are shown in Table 10.

[0121] As the amount of APS added to the soil increased, the amount of active substances produced increased, and the removal rate of quinclorac acid significantly improved. However, when the amount of APS added further increased to 3%, the removal rate no longer changed significantly. This may be because the free quinclorac acid in the soil was completely removed, while some was adsorbed in the soil and could not be removed by the oxidation system, but could be extracted.

[0122] As the Fe / SN-HC content increased from 0% to 1%, the removal rate increased significantly. However, the increase slowed down when the content increased to 2%, and finally, the removal rate decreased when the content reached 4%. This phenomenon is consistent with the observations in experiments on the degradation of quinclorac acid in water, which is attributed to the addition of excessive Fe to the system. 2+ It has a quenching effect on sulfate free radicals in the system, which is not conducive to the reaction.

[0123] Increasing the water-to-soil ratio and raising the reaction temperature can promote the reaction to some extent, which is conducive to the activation of APS and the full contact between active substances and pollutants.

[0124] Example 9

[0125] Material-activated ammonium persulfate for the remediation of dichloroquinoline acid phytotoxicity in tobacco

[0126] A solution of quinclorac acid was evenly sprayed onto a certain amount of soil to achieve a concentration of 0.08 mg / kg. -1After aging, the seedlings were placed in flowerpots. Uniformly growing tobacco seedlings with four new leaves were selected and transplanted into pots, one seedling per pot, with 10 seedlings per treatment. Three treatments were set up: CK (no remediation treatment), T1 (Jingfukang soil disinfectant, mainly composed of sodium bicarbonate, magnesium sulfate, boric acid, dipotassium hydrogen phosphate, active oxygen release agent, etc., pH=3.0-6.0, provided by Zhengzhou Huinong Pest Control Co., Ltd.), and T2 (root irrigation using the Fe / SN-HC+APS catalytic degradation system of Example 1). After transplanting, the seedlings were cultured until phytotoxicity symptoms appeared in the dichloroquinoline acid contamination group, at which point different remediation methods were applied.

[0127] The treatment method for Group T2 was as follows: the catalyst accounted for 2% of the soil mass, and the APS accounted for 3% of the soil mass. They were dissolved in water and watered every 10 days (until the soil in the pot was moistened and no water could be drained), for a total of 2 times.

[0128] The treatment method for group T1 is as follows: dissolve the catalyst in water at the same concentration as group T2, and water it once every 10 days (water until the soil in the pot is moist and no water can be drained), for a total of 2 times.

[0129] See below for the growth of tobacco seedlings under different treatments one month after restoration. Figure 12 The leaf length, leaf width, and plant height were measured, along with the number of normal leaves and the number of curled leaves, and the proportion of curled leaves was calculated.

[0130] From the plant appearance, the untreated group (CK) was significantly shorter with severely curled leaves. Compared to CK, the commercial foliar remediation treatment group (T1) showed increases in leaf length, leaf width, and plant height of 18.5%, 10.6%, and 8.3%, respectively, and a decrease in the proportion of curled leaves of 16.15%, indicating that the commercial foliar remediation agent has a certain effect on the repair of pesticide damage. In contrast, the catalytic degradation system group (T2) showed increases in leaf length, leaf width, and plant height of 50.2%, 66.7%, and 38.5%, respectively, and a decrease in the proportion of curled leaves of 48.8%. Furthermore, no curling was observed in the newly grown tobacco leaves, indicating that the catalytic degradation system was significantly more effective than the commercial foliar remediation agent in repairing pesticide damage in tobacco.

[0131] Using the same method, the remediation effect of the catalyst-drenched dichloroquinoline acid contamination groups (Comparative Examples 1-5) on tobacco plants exhibiting phytotoxicity symptoms was observed. The results showed that, compared to the control (CK), the leaf length, leaf width, and plant height of Comparative Examples 1-5 increased by 0-15.4%, 3.6-12.8%, and 1.5-9.6%, respectively, while the proportion of curled leaves decreased by 3.5%-17.2%. The remediation effects on tobacco phytotoxicity were significantly less effective than those of the catalytic degradation system (T2).

[0132] It should be noted that the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the scope of protection of this invention.

Claims

1. A multi-element co-modified carbon material, characterized in that, The raw materials include the following parts by weight: 8-15 parts water-soluble ferric salt, 7-14 parts thiourea, and 6-14 parts reed straw; The water-soluble ferric salt is ferric chloride, ferric nitrate, or ferric sulfate; The multi-element co-modified carbon material is obtained by modifying reed straw biochar with water-soluble trivalent iron salt and thiourea as modifiers through a one-step hydrothermal method.

2. A method for preparing a multi-element co-modified carbon material as described in claim 1, characterized in that, Includes the following steps: Water-soluble ferric salts and thiourea were dissolved in a solvent, and then reed straw was added and mixed evenly. A hydrothermal reaction was carried out, and the resulting product was washed, dried, ground, and sieved to obtain the multi-element co-modified carbon material.

3. The preparation method according to claim 2, characterized in that, Reed stalks are dried, crushed, and sieved into powder particles with a sieve mesh size of 20-40.

4. The preparation method according to claim 2, characterized in that, The hydrothermal reaction takes 16-24 hours and the hydrothermal reaction temperature is 160-220℃.

5. The preparation method according to claim 2, characterized in that, The drying temperature is 70-90℃, and the sieve opening is 80-100 mesh.

6. A catalytic system, characterized in that, The catalytic system includes the addition of persulfate to the multi-element co-modified carbon material according to claim 1.

7. The catalytic system according to claim 6, characterized in that, The mass ratio of the multi-element co-modified carbon material to persulfate is 2:(3.4-6.9); the persulfate includes one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

8. The application of the multi-element co-modified carbon material according to claim 1 or the catalytic system according to claim 6 or 7 in the degradation of dichloroquinoline acid.

9. The application of the multi-element co-modified carbon material according to claim 1 or the catalytic system according to claim 6 or 7 in the remediation of plants damaged by dichloroquinoline acid.

10. The application according to claim 8 or 9, characterized in that, The amount of the multi-element co-modified carbon material used is 0.1-0.3 g / L; the pH value of the system is 2-9; and the temperature is 10-40℃.

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