Application of eggshell-doped shaddock peel biochar in promoting degradation of sulfonylurea herbicide residues

Abstract

The invention discloses an application of eggshell doped shaddock peel charcoal in promoting degradation of sulfonylurea herbicide residues, the charcoal is prepared from eggshell doped shaddock peel through high-temperature carbonization, and the residues are one or two of nicosulfuron and bensulfuron methyl; the biological carbon is prepared by doping the eggshell with the shaddock peel, the degradation of the nicosulfuron and the bensulfuron methyl in the soil can be accelerated, the final residual quantity of the nicosulfuron and the bensulfuron methyl in the soil is reduced, and the biological carbon material shows relatively high catalytic activity and shows good application potential in the aspect of reducing the residual quantity of the nicosulfuron and the bensulfuron methyl in the soil.

Description

Technical Field

[0001] The present invention relates to the application of eggshell-doped pomelo peel biochar in promoting the degradation of sulfonylurea herbicide residues, belonging to the technical field of herbicide residue treatment. Background Art

[0002] Sulfonylurea herbicides are mainly used for controlling weeds in paddy fields, etc. Sulfonylurea herbicides have low volatility and the characteristic of persistent residues, being prone to pollute soil and groundwater, and being prone to cause phytotoxicity to sensitive crops planted subsequently. As selective systemic conductive herbicides, while inhibiting weed growth and protecting the yield of gramineous crops, they will have toxic effects on sensitive crops with similar metabolic pathways to weeds, such as solanaceous crops.

[0003] After the application of sulfonylurea herbicides, part of them will remain in the soil, water body and crops in the form of the parent body. As common sulfonylurea herbicides, the residues of nicosulfuron and bensulfuron-methyl have significant effects on both soil and plants. For soil microorganisms, after the application of nicosulfuron, the number of bacteria in the soil decreases significantly, while the numbers of fungi and actinomycetes increase significantly; the residue of bensulfuron-methyl will reduce the diversity of the soil microbial community structure and affect the normal functions of soil microorganisms. For the physical and chemical properties of the soil, nicosulfuron has a significant effect on the content of soil alkaline hydrolyzable nitrogen, and its content first increases and then decreases with the application dose; bensulfuron-methyl also has an adverse effect on the physical and chemical properties of the soil. For plant growth, nicosulfuron has an obvious growth inhibitory effect on sensitive crops such as tobacco, manifested as the inhibition of plant height and leaf area, and obvious chlorosis of new leaves; the residue of bensulfuron-methyl has inhibitory effects on the growth of crops such as corn, peanut, soybean, and cucumber to varying degrees.

[0004] Biochar can promote the degradation of sulfonylurea herbicide residues to a certain extent. First, biochar has a rich pore structure and a large specific surface area, which can adsorb sulfonylurea herbicides, reducing their mobility and bioavailability in the soil; second, biochar can provide a suitable living environment for microorganisms, promoting the growth and reproduction of microorganisms, thereby enhancing the degradation ability of microorganisms to sulfonylurea herbicides; third, some functional groups and active sites in biochar can catalyze the chemical degradation of sulfonylurea herbicides. The application of plant-derived biochar materials in the field of herbicide residues has natural advantages. First, there are many types of plant-derived biomass, which are widely distributed and easily available; second, plant-derived biochar materials themselves have good physical and chemical properties and are excellent adsorption materials; at the same time, they have the advantages of being renewable and having good biodegradability. Applying them in the field of herbicide residues not only has good economy but also can prevent the materials themselves from polluting the environment, etc.

[0005] As the types of grapefruit pulp processed products continue to increase, how to effectively deal with the grapefruit peel has become an increasingly prominent issue. At present, grapefruit peel is mainly treated by composting and landfilling, but these methods have the risk of environmental pollution and mold contamination. Although some methods for environmental remediation using grapefruit peel biochar have been developed, the effect is not ideal. The existing document (publication number: CN119034680A) discloses a preparation method and application of aluminum-modified grapefruit peel biochar, which modifies grapefruit peel biochar by sodium aluminate to obtain biochar that can remove fluoride in water. The existing document (publication number: CN114832778A) discloses a grapefruit peel biochar for adsorbing arsenic and its preparation method and application, which sequentially performs pre-treatment, solid phase carbonization and grinding of grapefruit peel to obtain biochar that can remove arsenic in soil. However, the current grapefruit peel biochar is not effective in treating sulfonylurea herbicide residues, and further research is needed to improve. Summary of the invention

[0006] Based on the above, the present invention provides a method for preparing biochar by doping eggshell with grapefruit peel to improve the ability to degrade sulfonylurea herbicide residues.

[0007] The technical solution of the present invention is: application of eggshell-doped grapefruit peel biochar in promoting the degradation of sulfonylurea herbicide residues, the biochar is prepared by high-temperature carbonization of eggshell-doped grapefruit peel, and the residue is one or both of nicosulfuron-methyl and benzylsulfuron-methyl.

[0008] Preferably, the method for preparing biochar comprises:

[0009] S1: Mix and fully grind grapefruit peel powder and egg shell powder to obtain egg shell-doped grapefruit peel powder;

[0010] S2: putting the eggshell-doped grapefruit peel powder into a tube furnace for high-temperature carbonization, and the whole process is completed in an air atmosphere to obtain carbonized eggshell-doped grapefruit peel;

[0011] S3: The carbonized eggshell-doped grapefruit peel is washed with ultrapure water for several times until the pH of the filtrate reaches neutral, and then dried to obtain the eggshell-doped grapefruit peel biochar.

[0012] Preferably, in step S1, the grapefruit peel powder and the egg shell powder are mixed in a mass ratio of 1 / 1 to 1 / 10.

[0013] Preferably, in step S2, the high temperature carbonization process is: from room temperature to 400-800°C, then maintained for 1-3 hours, and then naturally cooled to room temperature.

[0014] Preferably, when removing the herbicide residue, 1% to 10% eggshell-doped grapefruit peel biochar is added to the soil and stirred evenly.

[0015] The present invention relates to a technical method for the synergistic degradation of nicosulfuron and bensulfuron-methyl residues by a metal-plant-derived biochar composite, and its technical principle is based on the adsorption-catalysis synergistic mechanism. Specifically, a biochar carrier with a high specific surface area and porous structure is obtained by pyrolyzing plant-derived biomass, and the active metal calcium (provided by eggshells) component is uniformly immobilized on its surface and pores by chemical loading. The carbon-rich structure of the biochar efficiently adsorbs sulfonylurea herbicide molecules through π-π interactions, hydrogen bonds, and pore interception effects, achieving local enrichment of pollutants. At the same time, the loaded metal component triggers the cleavage of the urea bridge bond and heterocyclic structure in the sulfonylurea molecule through Fenton-like reactions, coordination catalysis, or electron transfer, and finally mineralizes into CO2, H2O, and inorganic ions. The synergistic effect of the two significantly improves the degradation kinetic efficiency, where the metal active sites lower the reaction activation energy, and the conductivity and surface functional groups (such as carboxyl and carbonyl) of the biochar further promote electron transfer and the continuous generation of free radicals (·OH / SO4 -· ). This technology has the characteristics of strong environmental compatibility and no secondary pollution, and is suitable for the efficient targeted removal of trace sulfonylurea herbicides in soil.

[0016] Beneficial effects of the present invention: The present invention prepares biochar by doping eggshells with pomelo peel, which can accelerate the degradation of nicosulfuron and bensulfuron-methyl in soil and reduce their final residues in soil. This biochar material exhibits high catalytic activity and shows good application potential in reducing the residues of nicosulfuron and bensulfuron-methyl in soil. Description of the Drawings

[0017] Figure 1 It is the electron micrograph of pomelo peel biochar;

[0018] Figure 2 It is the electron micrograph of eggshell biochar;

[0019] Figure 3 It is the electron micrograph of eggshell-doped pomelo peel biochar;

[0020] Figure 4 It is the degradation curve of nicosulfuron;

[0021] Figure 5 It is the degradation half-life diagram of nicosulfuron;

[0022] Figure 6 It is the degradation curve of bensulfuron-methyl.

[0023] Figure 7 It is the degradation half-life diagram of bensulfuron-methyl; Detailed Embodiments

[0024] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0025] Example 1: Preparation of eggshell-doped pomelo peel biochar

[0026] S1 Wash the pomelo peel, dry it, and then crush it to obtain pomelo peel powder; wash the eggshell, dry it, and then crush it to obtain eggshell powder; weigh the pomelo peel powder and eggshell powder according to a mass ratio of 2:1, mix them, and place them in a mortar for sufficient grinding to obtain eggshell-doped pomelo peel powder;

[0027] S2 Put the eggshell-doped pomelo peel powder into a tube furnace for high-temperature carbonization. The high-temperature carbonization process is as follows: heat up to 500 °C at a rate of 10 °C / min and hold for 2 h, and then naturally cool to room temperature. The whole process is completed in an air atmosphere to obtain carbonized eggshell-doped pomelo peel;

[0028] S3 Wash the carbonized eggshell-doped pomelo peel with ultrapure water several times until the pH of the filtrate reaches neutral, and then dry it to obtain eggshell-doped pomelo peel biochar. Its electron micrograph is as Figure 3 shown.

[0029] Comparative Example 1: Preparation of pomelo peel biochar

[0030] S1 Wash the pomelo peel, dry it, and then crush and grind it to obtain pomelo peel powder;

[0031] S2 Put the pomelo peel powder into a tube furnace for high-temperature carbonization. The high-temperature carbonization process is as follows: heat up to 500 °C at a rate of 10 °C / min and hold for 2 h, and then naturally cool to room temperature. The whole process is completed in an air atmosphere to obtain carbonized pomelo peel;

[0032] S3 Wash the carbonized pomelo peel with ultrapure water several times until the pH of the filtrate reaches neutral, and then dry it to obtain pomelo peel biochar. Its electron micrograph is as Figure 1 shown.

[0033] Comparative Example 2: Preparation of eggshell biochar

[0034] S1 Wash the eggshell, dry it, and then crush and grind it to obtain eggshell powder;

[0035] S2 Put the eggshell powder into a tube furnace for high-temperature carbonization. The high-temperature carbonization process is as follows: heat it to 500 °C at a rate of 10 °C / min and keep it for 2 h, then cool it naturally to room temperature. The whole process is completed in an air atmosphere, and the carbonized eggshells can be obtained.

[0036] S3 Wash the carbonized eggshells several times with ultrapure water until the pH of the filtrate reaches neutral, and then dry them to obtain eggshell biochar. Its electron micrograph is as Figure 2 shown.

[0037] Experimental design:

[0038] Mix and spray herbicides on the soil at 0.5 times the recommended doses of nicosulfuron and bensulfuron-methyl. After applying the pesticides, add 2% pomelo peel biochar (Control 1), 2% eggshell biochar (Control 2), and 2% eggshell-doped pomelo peel biochar (Example 1) respectively and mix them evenly. Take soil samples at intervals of 2 h, 1, 3, 5, 7, 10, 14, 21, 28, 35, 42, and 60 days, with blank soil as the control.

[0039] Weigh the soil sample (10.00 g ± 0.01 g) and place it in a 50 mL polypropylene centrifuge tube. Add 20 mL of acetonitrile-acetic acid mixed solution (Vacetonitrile:Vacetic acid = 99:1) for ultrasonic-assisted extraction. After homogenizing the mixed system on a vortex oscillator (2500 r / min) for 10 min, add 2.0 g of anhydrous magnesium sulfate (MgSO4) for dehydration treatment, and continue to vortex and mix for 2 min. Then centrifuge it in a refrigerated centrifuge (5000×g, 4 °C, 5 min). Use a precision pipette to quantitatively transfer 1.0 mL of the supernatant to a 2 mL silanized centrifuge tube (containing 50 mg of C18-bonded silica gel adsorbent, particle size 50 μm), and activate the adsorbent and purify the matrix by vortex oscillation (2500 r / min, 30 s). After the purified solution is centrifuged twice (5000×g, room temperature, 2 min), take 800 μL of the supernatant and filter it through a 0.22 μm nylon membrane syringe filter for microfiltration. Immediately transfer the filtered solution to a pre-cooled LC-MS / MS injection vial and store it in the dark at -20 °C. All samples are completed for high-performance liquid chromatography-triple quadrupole tandem mass spectrometry (HPLC-MS / MS) detection and analysis within 24 h after preparation. Based on the detection data, construct a dynamic degradation model of pesticide residues, draw a degradation kinetic curve with time (t) as the independent variable and residual concentration (C) as the dependent variable, and perform nonlinear fitting using the first-order kinetic equation to calculate the degradation rate constant (k) and half-life (t1 / 2). Figure 4 is the degradation curve of nicosulfuron, Figure 5 is the half-life diagram of nicosulfuron degradation, Figure 6 is the degradation curve of bensulfuron-methyl, Figure 7 is the half-life diagram of bensulfuron-methyl degradation.

[0040] Table 1 Residual Concentrations of Nicosulfuron and Bensulfuron-methyl at Different Times (mg / kg)

[0041]

[0042]

[0043] Table 2 Degradation Kinetics Equations of Nicosulfuron and Bensulfuron-methyl

[0044]

[0045] As can be seen from Table 2, the half-life of nicosulfuron in eggshell-doped pomelo peel biochar (4.71 ± 0.56 days) was significantly shortened by 44.5% compared with that in blank soil (8.49 ± 1.16 days), and it was also better than that in the single biochar treatment groups (eggshell biochar: 6.28 ± 0.84 days; pomelo peel biochar: 7.84 ± 1.07 days). This advantage was also reflected in the degradation of bensulfuron-methyl, whose half-life reached the lowest value of 5.10 ± 0.64 days in the doped treatment group, being shortened by 39.1% compared with blank soil, indicating that this composite material has a universal degradation efficiency for sulfonylurea herbicides.

[0046] The improvement in the degradation rate was directly reflected in the pollutant residue dynamics. The eggshell-doped treatment group showed the lowest final residue amounts during the experimental period (nicosulfuron: 0.1478 mg / kg; bensulfuron-methyl: 0.1607 mg / kg), which were reduced by 22.2% and 19.3% respectively compared with blank soil (Table 2). Observed longitudinally, this material not only accelerated long-term degradation - the residual concentration of nicosulfuron at 60 days (0.132 mg / kg) was significantly lower than that in the blank group (0.19 mg / kg) and the single treatment groups (eggshell: 0.1772 mg / kg; pomelo peel: 0.1889 mg / kg), but also showed rapid adsorption characteristics at the initial stage (1 day), with the residual amount of bensulfuron-methyl (0.3757 mg / kg) being reduced by 10.4% compared with blank soil (0.4193 mg / kg).

[0047] The structure-function analysis of the material revealed its synergistic mechanism: calcium carbonate from eggshells enhanced the surface complexation ability by regulating the soil pH, while the mesoporous structure of pomelo peel biochar provided sufficient active sites. The coupling of the two formed an "adsorption-catalysis" dual-effect system. Eggshell-doped pomelo peel biochar demonstrated three advantages: (1) outstanding degradation efficiency, with the half-life shortening rate reaching 39.1 - 44.5%; (2) a broad action spectrum, showing significant removal effects on sulfonylurea herbicides (p < 0.05); (3) environmental friendliness, with the waste resource utilization rate reaching 82 - 85%. This "treating pollution with waste" strategy provided a new idea for the treatment of agricultural non-point source pollution.

[0048] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. Application of eggshell-doped grapefruit peel biochar in promoting the degradation of sulfonylurea herbicide residues, wherein the biochar is prepared by high-temperature carbonization of eggshell-doped grapefruit peel, and the residue is one or both of nicosulfuron-methyl and benzylsulfuron-methyl.

2. The application of the biochar according to claim 1 in promoting the degradation of herbicide residues, characterized in that, The method for preparing biochar comprises: S1: Mix and fully grind grapefruit peel powder and egg shell powder to obtain egg shell-doped grapefruit peel powder; S2: putting the eggshell-doped grapefruit peel powder into a tube furnace for high-temperature carbonization, and the whole process is completed in an air atmosphere to obtain carbonized eggshell-doped grapefruit peel; S3: The carbonized eggshell-doped grapefruit peel is washed with ultrapure water for several times until the pH of the filtrate reaches neutral, and then dried to obtain the eggshell-doped grapefruit peel biochar.

3. The application of the biochar according to claim 2 in promoting the degradation of herbicide residues, characterized in that, In step S1, grapefruit peel powder and egg shell powder are mixed in a mass ratio of 1 / 1 to 1 / 10.

4. The application of the biochar according to claim 2 in promoting the degradation of herbicide residues, characterized in that, In step S2, the high temperature carbonization process is: from room temperature to 400-800°C, then maintained for 1-3 hours, and then naturally cooled to room temperature.

5. Use of the biochar according to claim 1 in promoting degradation of herbicide residues, characterized in that, When removing herbicide residues, add 1% to 10% eggshell-doped grapefruit peel biochar to the soil and mix well.

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