A soil residual pesticide degradation agent and its application

Abstract

A soil pesticide residue degrader and its application. The soil pesticide residue degrader of the present invention comprises the following components: a montmorillonite-hydrothermal carbon composite material and a persulfate; the montmorillonite-hydrothermal carbon composite material is prepared by a hydrothermal reaction using montmorillonite and a biomass carbon source as raw materials, wherein the biomass carbon source is at least one of sucrose and starch. The application of the soil pesticide residue degrader of the present invention is specifically performed as follows: the soil pesticide residue degrader is added to the pesticide-containing soil to be treated, mixed thoroughly, and then irrigated with water to carry out the pesticide degradation reaction. The soil pesticide residue degrader of the present invention can not only quickly degrade pesticide residues in the soil without secondary pollution, but also alleviate the herbicide damage to crops, improve soil fertility, and promote crop growth, with low investment and good effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of agriculture, and in particular relates to a soil residual pesticide degradation agent and application thereof. Background Art

[0002] Pesticides have made significant contributions to increasing and stabilizing crop yields, but some pesticides have long residual effects and are difficult to degrade in the soil, severely polluting the soil ecosystem. Quinclorac has been reported to have a half-life of up to 450 days in oxygen-rich soil (PPDB, 2021). Fields treated with quinclorac are generally not suitable for planting eggplant, tobacco, tomatoes, and other crops for 10-12 months, as this can easily cause severe pesticide damage (He Yaxu et al., 2021). Sulfensulfuron in soil can easily cause phytotoxicity to the sensitive subsequent crop, wheat (Wang et al., 2022), reduce soil microbial activity and biomass (Damin et al., 2022), and cause pathological changes and DNA damage in earthworms (Li et al., 2020). Furthermore, it can be toxic to duckweed, Scenedesmus obliquus, Myriophyllum spicate, and tadpoles through rainwater erosion, leaching, surface runoff, and groundwater circulation (Kong et al., 2020; Freitas et al., 2017). Oxadiazon inhibits the germination and reproduction of fungal spores in the rhizosphere of legumes (Upadhyay et al., 2020); fomesafen affects the activity of microorganisms and enzymes in the soybean rhizosphere and is toxic to earthworms (Zhou et al., 2018; Chang et al., 2021); oxyfluorfen affects soil microbial populations and damages the livers of loaches (Filimon et al., 2021); and afenapyr affects soil pH, temperature, and nitrogen, sulfur, and phosphorus content, reducing plant nutrient absorption (Caraba et al., 2023). In summary, among the commonly used pesticides in production, long-residue varieties have varying degrees of negative impacts on soil microorganisms, soil fauna, sensitive crops, and soil nutrients, posing a serious threat to the soil ecosystem. Commonly used methods for remediating pesticide residue contamination in soil include flooding, adsorption, photocatalytic degradation, microbial degradation, and phytoremediation.

[0003] Among the commonly used remediation methods, irrigation and washing can cause secondary contamination (Tran et al., 2022). Adsorption also involves desorption, and herbicides remain in the soil. Photocatalytic degradation requires a light source, and its effectiveness is significantly affected by soil depth (Kaur et al., 2021). In contrast, microbial degradation offers advantages such as low cost, good environmental compatibility, and suitability for large-scale deployment. However, these technologies present challenges such as difficulty in selecting dominant strains, poor field survival, low herbicide mineralization rates, and inconsistent efficacy (Gehrke et al., 2020; Melo et al., 2017), and most research remains limited to the laboratory stage. While phytoremediation is gaining popularity worldwide, most research focuses on selecting and improving dominant plants, and remediation efficiency remains to be improved (Mielke et al., 2020). In summary, currently used remediation methods all have limitations, making it difficult to fundamentally address the problem of long-lasting herbicide residues in soil. Summary of the Invention

[0004] The present invention aims to address the deficiencies of the above-mentioned prior art and provides a soil residual pesticide degrading agent and its application. The soil residual pesticide degrading agent of the present invention can quickly degrade pesticide residues in the soil, has simple operation, a short degradation cycle and good degradation effect.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] The soil residual pesticide degradation agent of the present invention comprises the following components: montmorillonite-hydrothermal carbon composite material and persulfate.

[0007] Preferably, the montmorillonite-hydrothermal carbon composite material is prepared by hydrothermal reaction using montmorillonite and a biomass carbon source as raw materials, wherein the biomass carbon source is preferably at least one of sucrose and starch. The montmorillonite-hydrothermal carbon composite material is preferably at least one of a sucrose-montmorillonite hydrothermal carbon composite material and a starch-montmorillonite hydrothermal carbon composite material.

[0008] Preferably, the persulfate includes at least one of peroxymonosulfate and peroxydisulfate, preferably peroxymonosulfate.

[0009] Preferably, the mass ratio of montmorillonite to biomass carbon source is 1:5 to 3:1.

[0010] The invention discloses a method for preparing a montmorillonite-hydrothermal carbon composite material, which adopts a hydrothermal method.

[0011] Preferably, the hydrothermal reaction temperature of the hydrothermal method is 160-220°C (preferably 180-200°C).

[0012] Preferably, the hydrothermal reaction time of the hydrothermal method is 5 hours or more (preferably 8 to 12 hours).

[0013] Montmorillonite-hydrothermal carbon composite material is an activator or catalyst for persulfate. The efficiency of persulfate in degrading organic pollutants is very low. After activation by montmorillonite-hydrothermal carbon composite material, sulfate radicals (SO4 ·- ) and hydroxyl radicals (·OH) and other active substances that can quickly degrade organic matter.

[0014] The preparation method of sucrose-montmorillonite hydrothermal carbon composite material can be specifically performed by the following operations:

[0015] Montmorillonite (MMT) was acidified with dilute hydrochloric acid for 24 hours and then repeatedly washed with ultrapure water. The acidified montmorillonite (MMT) was washed to a near-neutral pH, dried in a 105°C oven for 24 hours, and ground through a 100-mesh sieve for later use. A certain amount of sucrose (SUC) was weighed into a 250mL beaker, 100mL of pure water was added, and the mixture was stirred with a magnetic stirrer until completely dissolved. A certain amount of montmorillonite (MMT) was then weighed and added to the sucrose (SUC) solution. Stirring was continued for 30 minutes to thoroughly mix the mixture. The mass ratios of SUC to MMT were 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, and 1:5, with the total mass maintained at 10.00g. The mixture was transferred to a reactor and allowed to react for 10 hours at various temperatures (140°C, 160°C, 180°C, 200°C, and 220°C). After complete cooling, the reactor was opened and the prepared hydrothermal carbon composite material was removed. The mixture was washed three times with ultrapure water and twice with anhydrous ethanol. The resulting black solid powder was oven-dried at 105°C for 24 hours. After grinding and passing through a 100-mesh sieve, the sucrose-montmorillonite hydrothermal carbon composite material was obtained. Degradation experiments revealed that the optimal conditions for preparing the hydrothermal carbon composite material were a 1:2 ratio of SUC to MMT and a hydrothermal reaction temperature of 180°C.

[0016] Preparation method of starch-montmorillonite hydrothermal carbon composite material:

[0017] Montmorillonite powder was added to a beaker, and dilute hydrochloric acid (concentrated hydrochloric acid: water = 1:4) was added at a ratio of 1:5 (w / v). After stirring on a magnetic stirrer for 24 hours, the mixture was washed three times with ultrapure water. The acidified montmorillonite was then dried in an oven at 105°C for 24 hours. Finally, the dried acidified montmorillonite was ground through a 100-mesh sieve for later use. After acidified montmorillonite and starch were mixed at various mass ratios (1:1, 1:2, 1:3, and 2:1), ultrapure water was added at a 1:10 (w / v) ratio. After stirring for 1 hour, the mixture was added to a polytetrafluoroethylene-lined hydrothermal reactor. The reactor was then placed in an oven and reacted for 10 hours at various temperatures (140, 160, 180, 200, 220, 240, and 260°C). After cooling to room temperature, the hydrothermal carbonized product was removed and washed three times with ultrapure water and twice with ethanol. The solid product was collected and dried in an oven at 100°C to constant weight. After grinding, it was passed through a 100-mesh sieve to obtain a starch-montmorillonite hydrothermal carbon composite and stored in a desiccator. Degradation experiments revealed that the starch-montmorillonite hydrothermal carbon composite prepared at a reaction temperature of 200°C and a montmorillonite:starch ratio of 1:2 exhibited the best activation properties.

[0018] The present invention uses biomass carbon sources sucrose and montmorillonite to prepare a composite material sucrose-montmorillonite hydrothermal carbon by a hydrothermal method, and uses biomass carbon sources starch and montmorillonite to prepare a composite material starch-montmorillonite hydrothermal carbon by a hydrothermal method. The sucrose-montmorillonite hydrothermal carbon and / or the starch-montmorillonite hydrothermal carbon are then used as persulfate activators to participate in pesticide degradation.

[0019] Preferably, the sucrose-montmorillonite hydrothermal charcoal is prepared from montmorillonite and sucrose in a mass ratio of 1:5 to 3:1 (preferably 2:1), and the starch-montmorillonite hydrothermal charcoal is prepared from montmorillonite and starch in a mass ratio of 1:1 to 2:1 (preferably 1:2).

[0020] Preferably, the sucrose-montmorillonite hydrothermal charcoal, starch-montmorillonite hydrothermal charcoal, and persulfate are all in the form of powders. Before use, the montmorillonite-hydrothermal charcoal composite material and persulfate can be stored separately or mixed, but must be kept dry to avoid contact with water, which would cause the reaction to fail.

[0021] The application of the soil residual pesticide degrading agent of the present invention is specifically performed as follows: adding the soil residual pesticide degrading agent to the pesticide-containing soil to be treated, fully mixing, and then irrigating with water to carry out the pesticide degradation reaction.

[0022] Preferably, the soil residual pesticide degrading agent is applied from 3 to 7 days after the previous crop is harvested to 3 to 7 days before the next crop is sown.

[0023] Preferably, the pesticide degrading agent is applied alone.

[0024] Preferably, the pesticides include but are not limited to long-residue pesticides. Preferably, the pesticides include but are not limited to one or a combination of at least two of the hormone herbicide quinclorac, the protoporphyrinogen oxidase inhibitor herbicides oxadiazon, fomesafen, and sulfentrazone.

[0025] Preferably, when sucrose is selected as the biomass carbon source in the pesticide degrading agent, 10-40 g of the sucrose-montmorillonite hydrothermal carbon composite material and 4-20 g of persulfate are added per 1 kg of the pesticide-containing soil to be treated. Preferably, 20-30 g of the sucrose-montmorillonite hydrothermal carbon composite material and 16-20 g of persulfate are added per 1 kg of the pesticide-containing soil to be treated.

[0026] Preferably, when starch is selected as the biomass carbon source in the pesticide degrading agent, 5-25g of starch-montmorillonite hydrothermal carbon composite material and 4-40g of persulfate are added per 1kg of pesticide-containing soil to be treated. Preferably, 10-25g of starch-montmorillonite hydrothermal carbon composite material and 12-35g of persulfate are added per 1kg of pesticide-containing acidic soil to be treated. Preferably, 10-25g of starch-montmorillonite hydrothermal carbon composite material and 10-40g of persulfate are added per 1kg of pesticide-containing neutral soil to be treated.

[0027] Preferably, the method of fully mixing is plowing, and the plowing depth is 10 to 20 cm.

[0028] Preferably, the amount of irrigation water added is 1-15 kg / m 2 .

[0029] Preferably, the time for the pesticide degradation reaction after the irrigation water is no less than 12 hours.

[0030] As a preferred technical solution, the pesticide degradation method comprises the following steps:

[0031] (1) adding a soil residual pesticide degrading agent to the pesticide-containing soil to be treated, adding 20 g of sucrose-montmorillonite hydrothermal carbon composite material and 16 g of persulfate per 1 kg of the pesticide-containing soil to be treated; or adding 20 g of starch-montmorillonite hydrothermal carbon composite material and 20 g of persulfate per 1 kg of the pesticide-containing soil to be treated;

[0032] (2) Plowing the soil to mix the pesticide degrader with the soil, with a plowing depth of 10 to 20 cm;

[0033] (3) Irrigate the soil to make it moist, with an irrigation rate of 1 to 15 kg / m 2 , the pesticide degradation reaction time is not less than 12h.

[0034] The pesticide degrader of the present invention can degrade most pesticides remaining in the soil. Preferably, the pesticide is one or a combination of at least two of the hormone herbicides such as quinclorac, and the protoporphyrinogen oxidase inhibitor herbicides such as oxadiazon, fomesafen, and sulfentrazone.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The pesticide degrading agent of the present invention has a simple production process and low production cost, can alleviate the damage of pesticide residues, especially herbicide residues, to crops, improve soil nutrients, and promote crop growth;

[0037] (2) The present invention uses a preferred sucrose-montmorillonite hydrothermal charcoal and a persulfate combination. Under optimal conditions, the reaction with the common long-residual herbicides dichloroquine, oxadiazon, fomesafen, and sulfentrazone in the soil for 12 hours can achieve a degradation rate of more than 90%. The present invention uses a preferred starch-montmorillonite hydrothermal charcoal and a persulfate combination. Under optimal conditions, the reaction with the common long-residual herbicide dichloroquine in the soil for 12 hours can achieve a degradation rate of more than 85%.

[0038] (3) The pesticide degradation method of the present invention is simple to operate, has a short degradation cycle, and has a good degradation effect.

[0039] The soil residual pesticide degrader of the present invention can not only quickly degrade pesticide residues in the soil without secondary pollution, but also alleviate the herbicide damage to crops, improve soil fertility, and promote crop growth, with low investment and good effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a graph showing the degradation effect of the herbicide quinclorac in soil after treatment with a combination of sucrose-montmorillonite hydrothermal carbon composite material and persulfate as degradation agents in Example 1;

[0041] Figure 2 Graph showing the residual data of the herbicide quinclorac in soil after treatment with the sucrose-montmorillonite hydrothermal carbon composite material (SUCH4@MMT) and persulfate, the montmorillonite (MMT) and persulfate, and the sucrose hydrothermal carbon (SUCH4) and persulfate, respectively, in Example 1;

[0042] Figure 3 This is a graph showing the effect of treating soil with the pesticide degrader of Example 2 (a combination of sucrose-montmorillonite hydrothermal carbon composite material and persulfate) on alleviating the phytotoxicity of quinclorac to tomatoes (16 days after transplanting); Figure 3 (a) is a real picture of tomato growth. Figure 3 (b) is the data graph of tomato plant height results; different letters indicate statistically significant differences among groups (P<0.05);

[0043] Figure 4 This is a physical diagram showing the effects of different concentrations of pesticide degraders on pepper growth in Example 3;

[0044] Figure 5 This is a physical diagram showing the effects of different concentrations of pesticide degraders on eggplant growth in Example 3;

[0045] Figure 6 This is a physical diagram showing the effects of different concentrations of pesticide degraders on rice growth in Example 3;

[0046] Figure 7 This is a diagram showing the effect of treating soil with the pesticide degrader (CWS-MMT / PMS) (a combination of starch-montmorillonite hydrothermal carbon composite material and persulfate) in alleviating the damage of tobacco to quinclorac (QNC) (30 days after transplanting) in the example. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below with reference to specific embodiments and accompanying drawings.

[0048] Example 1

[0049] The soil residual pesticide degradation agent of the present embodiment, component is sucrose-montmorillonite hydrothermal carbon composite material and persulfate potassium monopersulfate (PMS).Wherein sucrose-montmorillonite hydrothermal carbon is prepared by hydrothermal method, is by the mass ratio of montmorillonite, biomass carbon source sucrose is 2: 1, and hydrothermal reaction temperature is 180 DEG C; Hydrothermal reaction time is prepared for 10 hours, and potassium monopersulfate (PMS) is commercially available.The specific operation of using degradation agent to degrade dichloroquinac in soil is: add pesticide degradation agent (i.e. sucrose-montmorillonite hydrothermal carbon 20g / kg and PMS16g / kg) in the soil containing 20mg / kg dichloroquinac, add water, make water-soil ratio 4: 1, react 1,2,4,8,12h and take samples respectively, detect the residual amount of dichloroquinac in soil, calculate the degradation rate of dichloroquinac.

[0050] The pesticide degradation method of this embodiment includes the following steps:

[0051] (1) Adding a soil residual pesticide degrader to the pesticide-containing soil to be treated, adding 20 g of sucrose-montmorillonite hydrothermal charcoal and 16 g of persulfate per 1 kg of the pesticide-containing soil to be treated;

[0052] (2) Plowing the soil to mix the pesticide degrader with the soil, with a plowing depth of 10 to 20 cm;

[0053] (3) Irrigate the soil to make it moist, with an irrigation rate of 5 kg / m 2 , the pesticide degradation reaction time is not less than 12h.

[0054] The pesticide degrader of this embodiment can degrade most pesticides remaining in the soil, which are one or a combination of at least two of the hormone herbicide quinclorac, the protoporphyrinogen oxidase inhibitor herbicides oxadiazon, fomesafen and sulfentrazone.

[0055] The research experiment involved a hydrothermal reaction of sucrose (SUC) and montmorillonite (MMT) at different mass ratios (3:1, 2:1, 1:1, 1:2, 1:3, 1:4, and 1:5) at different temperatures (140°C, 160°C, 180°C, 200°C, and 220°C) for 10 hours to prepare a series of sucrose-montmorillonite hydrothermal carbon composites. The results showed that the sucrose-montmorillonite hydrothermal carbon composite prepared at a sucrose-montmorillonite mass ratio of 1:2 and a hydrothermal reaction temperature of 180°C had the highest persulfate activation performance. After activating the composite with potassium permonosulfate (PMS) for 2 hours, the degradation rate of quinclorac reached over 89%. Figure 1 This is a diagram showing the degradation effect of the herbicide quinclorac in soil after treatment with a combination of sucrose-montmorillonite hydrothermal carbon composite material and persulfate as degradation agents in Example 1.

[0056] Application Effect

[0057] In this example, the degradation of the long-residual herbicide quinclorac was investigated using a pesticide degradation agent (i.e., a sucrose-montmorillonite hydrothermal carbon activated persulfate reaction system). Montmorillonite and sucrose hydrothermal carbon materials (prepared by hydrothermal treatment of sucrose using the same method) were used alone (except for the different degradation agents, all other parameters and conditions were identical) as controls.

[0058] Figure 2 Figure 1 shows the residual data of the herbicide quinclorac in soil after treatment with different substances as degradation agents in Example 1. The pesticide degradation agent in this example is a combination of sucrose-montmorillonite hydrochar (labeled as SUCH4@MMT in the figure) and potassium permonosulfate (PMS). Montmorillonite (labeled as MMT in the figure) represents the pesticide degradation effect of soil treated with the same method using the same amount of montmorillonite alone. Sucrose hydrochar (labeled as SUCH4 in the figure) represents the pesticide degradation effect of soil treated with the same method using the same amount of sucrose hydrochar alone.

[0059] from Figure 2 In the results, we can see that neither MMT nor SUCH4 alone can effectively activate PMS to degrade the long-residue herbicide quinclorac, with the removal rates of quinclorac within 8 hours being only 25.16% and 30.23%. When the sucrose-montmorillonite hydrothermal carbon (SUCH4@MMT) composite material is added to the reaction system, the degradation rate of quinclorac reaches 97.36% within 8 hours.

[0060] Example 2

[0061] Alleviation of the long-residual herbicide quinclorac damage by using the pesticide degrader of Example 1 (i.e., sucrose-montmorillonite hydrothermal carbon activated persulfate reaction system)

[0062] Tomato plants were transplanted using blank soil, quinclorac-poisoned soil (the soil containing pesticide before the treatment in Example 1), and soil after the treatment in Example 1. Figure 3 This is a diagram showing the effect of the pesticide degrader of Example 1 on alleviating the phytotoxicity of quinclorac to tomatoes (16 days after transplanting); Figure 3 (a) is a real picture of tomato growth. Figure 3 (b) is the data graph of tomato plant height results.

[0063] from Figure 3 (a) It can be clearly seen that quinclorac caused phytotoxicity to tomato plants 16 days after transplanting, manifested as curling of tomato leaves, reduction in leaf width and plant height. Figure 3 As shown in (b), in soil containing quinclorac, the inhibition rate of tomato plant height reached 19.20%. However, after treating the soil containing quinclorac with the first pesticide degrader (using 20g / kg SUCH4@MMT and 16g / kg PMS, with a water-soil ratio of 4:1), tomato seedlings were transplanted. The tomato plant height was 17.58cm, which was not significantly different from the tomato plant height of the control group (17.40cm) after transplantation (P>0.05). These results show that the pesticide degrader system of Example 1 can effectively degrade quinclorac in the soil and alleviate the phytotoxicity of quinclorac to tomatoes.

[0064] Example 3

[0065] The pesticide degradation agent of Example 1 (i.e., sucrose-montmorillonite hydrothermal carbon activated persulfate reaction system) promotes crop growth

[0066] 10, 20, 40, and 80 g / kg of sucrose-montmorillonite hydrothermal carbon composite and 1.50 g / kg of potassium permonosulfate were added to blank soil, and pepper, eggplant, and rice were planted respectively. It was found that after 7 days of treatment, the plant height of pepper, eggplant, and rice were higher than that of the blank control, and the leaf width of pepper and eggplant was also higher than that of the blank control. Figure 4-6 , Figure 4 Figure 3 shows the effects of different concentrations of pesticide degraders on pepper growth. CK represents the blank control, and AD represents the addition of 10, 20, 40, and 80 g / kg of sucrose-montmorillonite hydrochar and 1.50 g / kg of potassium permonosulfate to the soil, respectively. Figure 5The figure shows the effects of different concentrations of pesticide degraders on eggplant growth in Example 3. In the figure, CK is a blank control, and AD is the result of adding 10, 20, 40, and 80 g / kg of sucrose-montmorillonite hydrochar and 1.50 g / kg of potassium monopersulfate to the soil, respectively. Figure 6 The figures are actual pictures showing the effects of different concentrations of pesticide degraders on rice growth in Example 3. In the figure, CK is a blank control, and AD represents the addition of 10, 20, 40, and 80 g / kg of sucrose-montmorillonite hydrochar and 1.50 g / kg of potassium monopersulfate to the soil, respectively.

[0067] It was confirmed that the pesticide degrading agent of Example 1 (i.e., the sucrose-montmorillonite hydrothermal carbon activated potassium peroxymonosulfate reaction system) can promote crop growth.

[0068] Example 4

[0069] The pesticide degradation agent of Example 1 (sucrose-montmorillonite hydrothermal carbon activated potassium peroxymonosulfate reaction system) can improve soil nutrients

[0070] 20g / kg sucrose-montmorillonite hydrothermal carbon composite and 1.50g / kg potassium permonosulfate were added to soil poisoned with 0.1mg / kg sulfentrazone. Blank soil (no pesticide degrader or pesticide added), sulfentrazone (added with 0.1mg / kg sulfentrazone), and sucrose-montmorillonite hydrothermal carbon and potassium permonosulfate (added with 20g / kg sucrose-montmorillonite hydrothermal carbon composite and 1.50g / kg potassium permonosulfate) served as controls. The soil was tested for alkaline-hydrolyzable nitrogen, available phosphorus, and available potassium. The test results are shown in Table 1. As shown in Table 1, the pesticide degrader of Example 1 (sucrose-montmorillonite hydrothermal carbon activated potassium permonosulfate reaction system) significantly increased soil nutrients, with both nitrogen and potassium contents exceeding those of the blank control. Alkaline-hydrolyzable nitrogen and available potassium increased by 123.2% and 52.0%, respectively, relative to the blank control. However, sulfentrazone reduced the alkaline-hydrolyzable nitrogen and available phosphorus in the soil, decreasing by 22.0% and 20.3% respectively compared with the blank soil. The above results show that the pesticide degrader of Example 1 (sucrose-montmorillonite hydrothermal carbon activated potassium peroxymonosulfate reaction system) can increase the content of alkaline-hydrolyzable nitrogen and available potassium in the soil. Table 1 Effect of sulfentrazone degradation by sucrose-montmorillonite hydrothermal carbon activated potassium peroxymonosulfate on the nitrogen, phosphorus and potassium content in the soil

[0071]

[0072] Note: Different letters in the same column indicate significant differences at the 0.05 level.

[0073] Example 5

[0074] The soil pesticide residue degradation agent of this embodiment comprises starch-montmorillonite hydrothermal charcoal and persulfate potassium permonosulfate (PMS). The starch-montmorillonite hydrothermal charcoal is prepared using a hydrothermal method, with a mass ratio of montmorillonite to biomass carbon source starch of 1:2, a hydrothermal reaction temperature of 200°C, and a hydrothermal reaction time of 10 hours. Potassium permonosulfate (PMS) is commercially available. The specific steps for using this degradation agent to degrade quinclorac in soil are the same as those in Example 1.

[0075] The pesticide degradation method of this embodiment includes the following steps:

[0076] (1) adding a soil residual pesticide degrader to the pesticide-containing soil to be treated, adding 20 g of starch-montmorillonite hydrothermal carbon composite material and 20 g of persulfate per 1 kg of the pesticide-containing soil to be treated;

[0077] (2) Plowing the soil to mix the pesticide degrader with the soil, with a plowing depth of 10 to 20 cm;

[0078] (3) Irrigate the soil to make it moist, with an irrigation rate of 5 kg / m 2 , the pesticide degradation reaction time is not less than 12h.

[0079] The experimental process of the research was as follows: lignin, starch, microcrystalline cellulose, carboxymethyl cellulose, etc. were used as carbon sources, and montmorillonite was used as the carrier. The carbon source and montmorillonite were reacted with the hydrothermal method at different mass ratios (1:1, 1:2, 1:3, 2:1) and different temperatures (140, 160, 180, 200, 220, 240, 260℃) for 10 hours to prepare 28 kinds of montmorillonite-hydrothermal carbon composite materials, which were activated with PMS to degrade dichloroquinoline. It was found that the starch-montmorillonite hydrothermal carbon composite material (CWSH2@MMT) prepared at a hydrothermal reaction temperature of 200℃ and a mass ratio of montmorillonite to starch of 1:2 had the best activation performance. The optimal activation performance condition was at 25℃, using 0.5g / L CWSH2@MMT to activate 2mM PMS to degrade 10mg / L dichloroquinoline in the soil. The reaction lasted for 4 hours, and the degradation rate of dichloroquinoline was 84.13%.

[0080] The pesticide degrader of this embodiment can degrade most pesticides remaining in the soil, which are one or a combination of at least two of the hormone herbicide quinclorac, the protoporphyrinogen oxidase inhibitor herbicides oxadiazon, fomesafen and sulfentrazone.

[0081] Degradation of the long-residual herbicide quinclorac by the pesticide degradation agent of this embodiment (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system)

[0082] Acidic Soil: The degradation efficiency of potassium permonosulfate (PMS) activated with different amounts of starch-montmorillonite hydrochar (CWSH2@MMT) for 10 mg / kg quinclorac in acidic soil is shown in Table 2. Variance analysis of quinclorac degradation rates revealed that the optimal addition amount of CWSH2@MMT for quinclorac in acidic soil ranged from 10 to 25 g per kg of soil, and the PMS:CWSH2@MMT ratio was 1.20 to 1.60:1. Quinclorac was efficiently degraded within a temperature range of 15-25°C, with a degradation rate exceeding 98% after 12 hours.

[0083] Neutral soil: The degradation effect of different amounts of starch-montmorillonite hydrothermal carbon (CWSH2@MMT) activated potassium persulfate (PMS) on the degradation of 10 mg / kg dichloroquinoline in neutral soil is shown in Table 3. By performing variance analysis on the degradation rate of dichloroquinoline, it can be seen that the optimal addition amount of CWSH2@MMT for degrading dichloroquinoline in neutral soil is 10-25 g in 1 kg of soil, and the ratio of PMS:CWSH2@MMT is 1.0:1-1.60:1. The temperature can be efficiently degraded in the range of 25-35 ° C in neutral soil, and the degradation rate of the reaction for 12 hours is more than 85%. Table 2 Degradation of dichloroquinoline in acidic soil by the pesticide degrader of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system)

[0084]

[0085]

[0086] Table 3 Degradation of quinclorac in neutral soil by the pesticide degradation agent of Example 5 (i.e. starch-montmorillonite hydrothermal carbon activated persulfate reaction system)

[0087]

[0088]

[0089] Example 6

[0090] The pesticide degrader of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system) alleviates the phytotoxicity of quinclorac to tobacco

[0091] Tobacco plants were transplanted using blank neutral soil (marked as CK), 0.04 mg / kg quinclorac poisoned soil (marked as 0.04 mg / kg QNC), 0.4 mg / kg quinclorac poisoned soil (marked as 0.4 mg / kg QNC), 0.04 mg / kg quinclorac poisoned soil (marked as CWS-MMT / PMS+0.04 mg / kg QNC) treated with the pesticide degrader of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system), and 0.4 mg / kg quinclorac poisoned soil (marked as CWS-MMT / PMS+0.4 mg / kg QNC) treated with the pesticide degrader of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system). Figure 7 This is a graph showing the effect of the pesticide degrader in Example 5 on alleviating the damage of quinclorac to tobacco plants (30 days after transplanting). In this example, the water-soil ratio was 3:1, and the pesticide degrader (10 g / kg starch-montmorillonite hydrochar, 10 g / kg potassium permonosulfate) was used.

[0092] When the soil concentration of quinclorac was 0.04 and 0.4 mg / kg, the symptoms of tobacco damage after 30 days were as follows: Figure 7 As shown. 30 days after transplanting, tobacco seedlings that were not treated with the pesticide degrader of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system) showed obvious phytotoxicity. The higher the concentration of quinclorac, the more severe the phytotoxicity of tobacco, manifested as twisted and deformed heart leaves, severe leaf curling toward the back of the leaves, and severe suppression of plant height. After the 0.04 mg / kg quinclorac-poisoned soil was treated with the pesticide degrader of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system), tobacco seedlings grew normally, with leaf length and plant height almost approaching those of the blank control group. The inhibitory effect on leaf length, leaf width, and plant height of tobacco seedlings treated with the pesticide degrader of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system) was also significantly alleviated, indicating that treatment with the pesticide degrader of Example 5 can alleviate the phytotoxicity of quinclorac on tobacco.

Claims

1. A soil residual pesticide degradation agent, characterized in that: The invention comprises the following components: a montmorillonite-hydrothermal carbon composite material and persulfate; The montmorillonite-hydrothermal carbon composite material is prepared by hydrothermal reaction using montmorillonite and biomass carbon source as raw materials; The biomass carbon source is at least one of sucrose and starch; and / or the persulfate includes at least one of peroxymonosulfate and peroxydisulfate; and / or the montmorillonite-hydrothermal carbon composite material is at least one of a sucrose-montmorillonite hydrothermal carbon composite material and a starch-montmorillonite hydrothermal carbon composite material; The preparation method of sucrose-montmorillonite hydrothermal carbon composite material specifically adopts the following operations: Montmorillonite was acidified with dilute hydrochloric acid for 24 h and then repeatedly washed with ultrapure water. The pH value of the acidified montmorillonite was washed to near neutral, placed in an oven at 105°C for 24 h, and ground through a 100-mesh sieve for later use. A certain amount of sucrose was weighed into a 250 mL beaker, 100 mL of pure water was added, and the mixture was stirred with a magnetic stirrer until completely dissolved. Then, a certain amount of montmorillonite was weighed and added to the sucrose solution. Stirring was continued for 30 min to fully mix the mixture. The mass ratio of sucrose to montmorillonite was 1:2, and the total mass was maintained at 10.00 g. The mixture was transferred to the inner liner of a reactor and reacted at 180°C for 10 h. After it was completely cooled, the reactor was opened and the prepared hydrothermal carbon composite material was taken out. The mixture was first washed with ultrapure water three times and then washed with anhydrous ethanol twice. The resulting black solid powder was dried in an oven at 105°C for 24 h. After grinding, it was passed through a 100-mesh sieve to obtain the sucrose-montmorillonite hydrothermal carbon composite material. Preparation method of starch-montmorillonite hydrothermal carbon composite material: Montmorillonite powder was added to a beaker, and dilute hydrochloric acid was added. After stirring on a magnetic stirrer for 24 hours, the mixture was washed three times with ultrapure water. The acidified montmorillonite was then placed in a 105°C oven and dried for 24 hours. Finally, the dried acidified montmorillonite was ground through a 100-mesh sieve for use. The acidified montmorillonite and starch were mixed evenly at a ratio of 1:2, ultrapure water was added, and the mixture was stirred for 1 hour and then added to a hydrothermal reactor. The hydrothermal reactor was placed in an oven and reacted at 200°C for 10 hours. After the reaction was completed, the mixture was cooled to room temperature, the hydrothermal carbonization product was taken out, washed three times with ultrapure water and twice with ethanol, the solid product was collected, and the product was dried in a 100°C oven to constant weight. After grinding, the product was passed through a 100-mesh sieve to obtain a starch-montmorillonite hydrothermal carbon composite material.

2. The soil residual pesticide degradation agent according to claim 1, characterized in that The sucrose-montmorillonite hydrothermal charcoal, starch-montmorillonite hydrothermal charcoal and persulfate are all in powder form; and / or, before use, the montmorillonite-hydrothermal charcoal composite material and persulfate are stored separately, or mixed and stored but kept dry.

3. The use of the soil residual pesticide degrading agent according to claim 1 or 2, characterized in that: The specific operation is: add soil residual pesticide degrader to the pesticide-containing soil to be treated, mix thoroughly, and then irrigate with water to carry out pesticide degradation reaction.

4. The use of the soil residual pesticide degrading agent according to claim 3, characterized in that: The soil residual pesticide degrader is applied from 3 to 7 days after the previous crop is harvested to 3 to 7 days before the next crop is sown.

5. The use of the soil residual pesticide degrading agent according to claim 3 or 4, characterized in that: When sucrose is selected as the biomass carbon source in the pesticide degrading agent, 10 to 40 g of sucrose-montmorillonite hydrothermal carbon composite material and 4 to 20 g of persulfate need to be added for every 1 kg of pesticide-containing soil to be treated; and / or, when starch is selected as the biomass carbon source in the pesticide degrading agent, 5 to 25 g of starch-montmorillonite hydrothermal carbon composite material and 4 to 40 g of persulfate need to be added for every 1 kg of pesticide-containing soil to be treated.

6. The use of the soil residual pesticide degradation agent according to claim 3 or 4, characterized in that: The method of thorough mixing is tillage with a tillage depth of 10 to 20 cm; and / or, the addition of irrigation water at a rate of 1 to 15 kg / m 2 ; and / or, the time for pesticide degradation reaction after irrigation water is not less than 12 hours.

7. The use of the soil residual pesticide degrading agent according to claim 3 or 4, characterized in that: The degradable pesticide is one or a combination of at least two of the hormone herbicide quinclorac, the protoporphyrinogen oxidase inhibitor herbicides oxadiazon, fomesafen, and sulfentrazone.

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