Soil residual pesticide degradation agent and application thereof

Abstract

The invention relates to a soil residual pesticide degradation agent and application thereof, and the soil residual pesticide degradation agent comprises the following components: a montmorillonite-hydrothermal carbon composite material and persulfate, the montmorillonite-hydrothermal carbon composite material is prepared by taking montmorillonite and a biomass carbon source as raw materials through a hydrothermal reaction, and the biomass carbon source is at least one of cane sugar and starch. The application of the soil residual pesticide degradation agent comprises the following specific operation steps: adding the soil residual pesticide degradation agent into pesticide-containing soil to be treated, fully and uniformly mixing, and then irrigating water to carry out pesticide degradation reaction. The soil residual pesticide degradation agent can rapidly degrade pesticide residues in soil, is free of secondary pollution, can relieve phytotoxicity of herbicides to crops, improves soil fertility, promotes crop growth, and is low in investment and good in effect.

Description

Technical Field

[0001] The 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 great contributions to increasing and stabilizing crop yields, but some pesticides have long residual periods and are difficult to degrade in the soil, seriously polluting the soil ecological environment. It is reported that the half-life of quinclorac in soil with sufficient oxygen content is as long as 450 days (PPDB, 2021). Fields where quinclorac is applied should not be planted with eggplant, tobacco, tomatoes, etc. within 10-12 months, otherwise it is very easy to cause serious pesticide damage (He Yaxu et al., 2021). Sulfonamide in the soil can easily cause phytotoxicity to the subsequent sensitive crop wheat (Wang et al., 2022), reduce the activity and biomass of soil microorganisms (Damin et al., 2022), cause pathological changes in earthworm tissues and DNA damage (Li et al., 2020), and can be toxic to duckweed, Scenedesmus obliquus, Myriophyllum paniculate, and tadpoles through rainwater erosion, leaching, surface runoff, and groundwater circulation (Kong Xuanqing et al., 2020; Freitas et al., 2017). Oxyfluanid inhibits the germination and reproduction of fungal spores in the rhizosphere of leguminous plants (Upadhyay et al., 2020); fomesafen affects the activity of rhizosphere microorganisms and enzymes in soybeans and is toxic to earthworms (Zhou Shixiong et al., 2018; Chang et al., 2021); oxyfluorfen affects the soil microbial population and damages the liver of loach (Filimon et al., 2021); benifloxacin affects the soil pH, temperature, and nitrogen, sulfur, and phosphorus content, reducing the absorption of nutrients by plants (Caraba et al., 2023). In summary, among the commonly used pesticides in production, long-residue varieties have different degrees of negative effects on soil microorganisms, soil animals, sensitive crops, and soil nutrients, posing a serious threat to the soil ecological environment. For pesticide residue pollution in the soil, the commonly used treatment methods currently include water washing, adsorption, photocatalytic degradation, microbial degradation, and plant remediation.

[0003] Among the commonly used treatment methods, the leaching liquid from irrigation and washing fields will cause secondary pollution (Tran et al., 2022); if the adsorption method is used, desorption occurs at the same time as adsorption, and the herbicide still remains in the soil environment; photocatalytic degradation requires a light source, and the remediation effect is greatly affected by the soil depth (Kaur et al., 2021). In contrast, microbial degradation technology has the characteristics of low cost, good environmental compatibility, and suitability for large-scale use, but the degradation bacteria have problems such as difficulty in screening dominant strains, poor survival ability in the field, low mineralization rate of herbicides, and unstable effects (Gehrke et al., 2020; Melo et al., 2017.), and most of the research is still limited to the laboratory stage; although plant remediation is favored in countries around the world, most of the research focuses on the screening and improvement of dominant plants, and the remediation efficiency needs to be improved (Mielke et al., 2020). In summary, the commonly used treatment methods currently have certain limitations, and it is difficult to fundamentally solve the pollution problem of long-residue herbicides in the soil. Summary of the invention

[0004] The present invention aims to solve 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, 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, and 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 being activated by the montmorillonite-hydrothermal carbon composite material, sulfate radicals (SO4 ·- ) and hydroxyl radicals (·OH), which 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 washed repeatedly with ultrapure water. The pH value of the acidified montmorillonite (MMT) was washed to near neutral, placed in a 105°C oven for drying for 24 hours, and ground through a 100-mesh sieve for later use. Weigh a certain mass of sucrose (SUC) in a 250mL beaker, add 100mL of pure water, stir with a magnetic stirrer until completely dissolved, then weigh a certain mass of montmorillonite (MMT) and add it to the sucrose (SUC) solution, and continue stirring for 30 minutes to fully mix it. The mass ratio of SUC to MMT is 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, and its total mass is maintained at 10.00g. The mixture was transferred to the inner tank of the reactor and reacted for 10 hours at a certain temperature (140°C, 160°C, 180°C, 200°C, 220°C). After it was completely cooled, the reactor was opened and the prepared hydrothermal carbon composite material was taken out. It was first washed with ultrapure water 3 times and then washed with anhydrous ethanol 2 times. The obtained black solid powder was dried in an oven at 105°C for 24 hours. After grinding and passing through a 100-mesh sieve, the sucrose-montmorillonite hydrothermal carbon composite material was obtained. After degradation experiment screening, the optimal conditions for the preparation of the hydrothermal carbon composite material were a ratio of SUC to MMT of 1:2 and a hydrothermal reaction temperature of 180°C.

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

[0017] Add montmorillonite powder into a beaker, add dilute hydrochloric acid (concentrated hydrochloric acid: water = 1:4) in a ratio of 1:5 (w / v), stir on a magnetic stirrer for 24 hours, wash with ultrapure water 3 times, then place the acidified montmorillonite in an oven at 105°C and dry for 24 hours. Finally, grind the dried acidified montmorillonite through a 100-mesh sieve for use. After the acidified montmorillonite and starch were mixed evenly at different mass ratios (1:1, 1:2, 1:3, 2:1), ultrapure water was added at a ratio of 1:10 (w / v), stirred for 1h, and then added to a hydrothermal reactor with a polytetrafluoroethylene liner. The hydrothermal reactor was placed in an oven and reacted at different temperatures (140, 160, 180, 200, 220, 240, 260℃) for 10h. After the reaction was completed, it was cooled to room temperature, the hydrothermal carbonization product was taken out, washed three times with ultrapure water and twice with ethanol, and the solid product was collected. The product was dried in an oven at 100℃ to constant weight, and after grinding, it was passed through a 100-mesh sieve to obtain a starch-montmorillonite hydrothermal carbon composite material, which was stored in a desiccator. After degradation experiment screening, it was found that the starch-montmorillonite hydrothermal carbon composite material prepared at a reaction temperature of 200℃ and montmorillonite: starch = 1:2 had the best activation performance.

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

[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 the persulfate can be stored separately or mixed, but they must be kept dry to avoid contact with water and reaction failure.

[0021] The application of the soil residual pesticide degradation agent of the present invention is specifically performed as follows: adding the soil residual pesticide degradation agent to the soil containing pesticides to be treated, fully mixing, and then irrigating 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 oxadiazine, fomesafen, and sulfentrazone.

[0025] Preferably, 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 are added per 1 kg of the pesticide-containing soil to be treated. Preferably, 20 to 30 g of sucrose-montmorillonite hydrothermal carbon composite material and 16 to 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 to 25 g of starch-montmorillonite hydrothermal carbon composite material and 4 to 40 g of persulfate are added for every 1 kg of pesticide-containing soil to be treated. Preferably, 10 to 25 g of starch-montmorillonite hydrothermal carbon composite material and 12 to 35 g of persulfate are added for every 1 kg of acidic soil containing pesticides to be treated. Preferably, 10 to 25 g of starch-montmorillonite hydrothermal carbon composite material and 10 to 40 g of persulfate are added for every 1 kg of neutral soil containing pesticides to be treated.

[0027] Preferably, the method of sufficient mixing is tillage, and the tillage 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) tilling the soil and mixing the pesticide degrader with the soil at a tillage 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 degrading agent 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 hormone herbicides such as quinclorac, protoporphyrinogen oxidase inhibitor herbicides such as oxadiazine, fomesafen and sulfentrazone.

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

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

[0037] (2) The present invention adopts the preferred sucrose-montmorillonite hydrothermal charcoal and persulfate in combination, and under the preferred conditions, the degradation rate can reach more than 90% after reacting with the common long-residual herbicides dichloroquine, oxadiazine, fomesafen, and sulfentrazone for 12 hours; the present invention adopts the preferred starch-montmorillonite hydrothermal charcoal and persulfate in combination, and under the preferred conditions, the degradation rate can reach more than 85% after reacting with the common long-residual herbicide dichloroquine for 12 hours;

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

[0039] The soil residual pesticide degrading agent of the present invention can not only quickly degrade the 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 diagram showing the degradation effect of the herbicide quinclorac in soil after the sucrose-montmorillonite hydrothermal carbon composite material and persulfate are used as degradation agents in Example 1;

[0041] Figure 2 The residual data result graph of the herbicide quinclorac in the soil after the 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 in Example 1;

[0042] Figure 3 This is a diagram showing the effect of treating soil with the pesticide degrader (sucrose-montmorillonite hydrothermal carbon composite material and persulfate) in Example 2 to alleviate the pesticide damage 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 picture showing the effect of different concentrations of pesticide degrading agents on the growth of peppers in Example 3;

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

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

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

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

[0048] Example 1

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

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

[0051] (1) adding a soil residual pesticide degrading agent 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) tilling the soil and mixing the pesticide degrader with the soil at a tillage 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, and the pesticides are one or a combination of at least two of the hormone herbicide dichloroquine, the protoporphyrinogen oxidase inhibitor herbicides oxadiazine, fomesafen and sulfentrazone.

[0055] Research experimental process: Through the hydrothermal method, sucrose (SUC) and montmorillonite (MMT) were hydrothermally reacted at different mass ratios (3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5) at different hydrothermal temperatures (140℃, 160℃, 180℃, 200℃, 220℃) for 10h to prepare a series of sucrose-montmorillonite hydrothermal carbon composite materials. It was found that the sucrose-montmorillonite hydrothermal carbon composite material prepared when the mass ratio of sucrose to montmorillonite was 1:2 and the hydrothermal reaction temperature was 180℃ had the highest activation performance for persulfate. After activating it with potassium permonosulfate (PMS) to degrade dichloroquinoline acid for 2h, the degradation rate of dichloroquinoline acid reached more than 89%. Figure 1 This is a diagram showing the degradation effect of the herbicide dichloroquinoline in the soil after the sucrose-montmorillonite hydrothermal carbon composite material and persulfate are used as degradation agents in Example 1.

[0056] Application Effect

[0057] The pesticide degradation agent of this example (i.e., sucrose-montmorillonite hydrothermal carbon activated persulfate reaction system) was used to degrade the long-residue herbicide dichloroquine. At the same time, montmorillonite and sucrose hydrothermal carbon materials (obtained by hydrothermal treatment of sucrose in the same way) were used alone (except for the different degradation agents, other parameters and conditions were exactly the same) as controls.

[0058] Figure 2 The figure is a result graph of the residual data of the herbicide dichloroquinac in the soil after the treatment with different substances as degradation agents in Example 1; the pesticide degradation agent in this example is a combination of sucrose-montmorillonite hydrochar (marked as SUCH4@MMT in the figure) and potassium permonosulfate (PMS); montmorillonite (marked as MMT in the figure) represents the pesticide degradation effect of using the same amount of montmorillonite alone to treat the soil in the same way; sucrose hydrochar (marked as SUCH4 in the figure) represents the pesticide degradation effect of using the same amount of sucrose hydrochar material alone to treat the soil in the same way.

[0059] from Figure 2 In the figure, we can see that neither MMT nor SUCH4 alone can effectively activate PMS to degrade the long-residue herbicide quinclorac, and the removal rate of quinclorac within 8 hours is 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% at 8 hours.

[0060] Example 2

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

[0062] Tomato plants were transplanted using blank soil, quinclorac poisoned soil (soil containing pesticides before treatment in Example 1), and soil after treatment in Example 1. Figure 3 This is a diagram showing the effect of the pesticide degrading agent 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, which was manifested by curling of tomato leaves, reduced leaf width and plant height. Figure 3 As shown in (b), in the soil containing quinclorac, the inhibition rate of tomato plant height reached 19.20%. However, after the soil containing quinclorac was treated with the first pesticide degrader (using a dosage of SUCH4@MMT 20g / kg and PMS16g / kg, water-soil ratio 4:1), tomato seedlings were transplanted, and the tomato plant height was 17.58cm, which was not significantly different from the tomato plant height (17.40cm) of the control group 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, 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 was 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 The figure is a physical diagram showing the effect of different concentrations of pesticide degraders on the growth of peppers in Example 3, in which CK is a blank control, and AD is the addition of 10, 20, 40, 80 g / kg of sucrose-montmorillonite hydrothermal charcoal and 1.50 g / kg of potassium permonosulfate to the soil, respectively; Figure 5This is a physical diagram of the effect of different concentrations of pesticide degraders on eggplant growth in Example 3, in which CK is a blank control, and AD is the addition of 10, 20, 40, 80 g / kg of sucrose-montmorillonite hydrothermal charcoal and 1.50 g / kg of potassium permonosulfate to the soil respectively; Figure 6 This is a physical diagram of the effect of different concentrations of pesticide degraders on rice growth in Example 3, in which CK is a blank control, and AD is the addition of 10, 20, 40, 80 g / kg of sucrose-montmorillonite hydrothermal charcoal and 1.50 g / kg of potassium permonosulfate to the soil, respectively.

[0067] It was confirmed that the pesticide degradation 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 persulfate reaction system) can improve soil nutrients

[0070] 20g / kg sucrose-montmorillonite hydrothermal carbon composite material and 1.50g / kg potassium permonosulfate were added to the soil poisoned with 0.1mg / kg sulfentrazone, and blank soil (no pesticide degradation agent was added, and no pesticide was added), sulfentrazone (added with 0.1mg / kg sulfentrazone), sucrose-montmorillonite hydrothermal carbon and potassium permonosulfate (added with 20g / kg sucrose-montmorillonite hydrothermal carbon composite material and 1.50g / kg potassium permonosulfate) were used as controls. The contents of alkaline nitrogen, available phosphorus and available potassium in the soil were detected, and the test results are shown in Table 1. As can be seen from Table 1, the pesticide degradation agent of Example 1 (sucrose-montmorillonite hydrothermal carbon activated potassium permonosulfate reaction system) can significantly increase soil nutrients, and the nitrogen and potassium contents in the soil are higher than those of the blank control, and the alkaline nitrogen and available potassium are increased by 123.2% and 52.0% respectively relative to the blank control. Sulfonamide reduced the alkaline nitrogen and available phosphorus in the soil, which decreased 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 persulfate reaction system) can increase the content of alkaline nitrogen and available potassium in the soil. Table 1 Effect of sulfonamide degradation by sucrose-montmorillonite hydrothermal carbon activated potassium persulfate 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 residual pesticide degradation agent of this embodiment comprises starch-montmorillonite hydrothermal charcoal and persulfate potassium permonosulfate (PMS). The starch-montmorillonite hydrothermal charcoal is prepared by a hydrothermal method, with a mass ratio of montmorillonite and 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 of using the degradation agent to degrade dichloroquinoline in the soil are the same as those in Example 1.

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

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

[0077] (2) tilling the soil and mixing the pesticide degrader with the soil at a tillage 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: lignin, starch, microcrystalline cellulose, carboxymethyl cellulose, etc. were used as carbon sources, and montmorillonite was used as a 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 composites, which were activated with PMS to degrade dichloroquinoline. It was found that the starch-montmorillonite hydrothermal carbon composite (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 best 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, and the pesticides are one or a combination of at least two of the hormone herbicide dichloroquine, the protoporphyrinogen oxidase inhibitor herbicides oxadiazine, fomesafen and sulfentrazone.

[0081] Degradation of the long-residue 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 effect of different amounts of starch-montmorillonite hydrochar (CWSH2@MMT) activated potassium permonosulfate (PMS) to degrade 10 mg / kg dichloroquine in acidic soil is shown in Table 2. The variance analysis of the degradation rate of dichloroquine showed that the optimal addition amount of CWSH2@MMT in 1 kg of soil for degrading dichloroquine in acidic soil was 10-25 g, PMS:CWSH2@MMT was 1.20:1-1.60:1, and the temperature was within the range of 15-25 ° C. The degradation rate of 12 h of reaction was more than 98%.

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

[0091] Blank neutral soil (marked as CK), 0.04 mg / kg quinclorac acid poisoned soil (marked as 0.04 mg / kg QNC), 0.4 mg / kg quinclorac acid poisoned soil (marked as 0.4 mg / kg QNC), 0.04 mg / kg quinclorac acid poisoned soil (marked as CWS-MMT / PMS+0.04 mg / kg QNC) treated with the pesticide degrading agent of Example 5 (i.e. starch-montmorillonite hydrothermal carbon activated persulfate reaction system), 0.4 mg / kg quinclorac acid poisoned soil (marked as CWS-MMT / PMS+0.4 mg / kg QNC) treated with the pesticide degrading agent of Example 5 (i.e. starch-montmorillonite hydrothermal carbon activated persulfate reaction system) were used to transplant tobacco plants. Figure 7 The growth effect of the pesticide degrading agent in Example 5 on alleviating the phytotoxicity of quinclorac to tobacco (30 days after transplanting) is shown. In this example, the water-soil ratio is 3:1, and the pesticide degrading agent (10 g / kg starch-montmorillonite hydrocharcoal, 10 g / kg potassium permonosulfate) is 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, the tobacco seedlings that were not treated with the pesticide degrading agent of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system) showed obvious phytotoxicity, and the higher the concentration of dichloroquine acid, the more serious the phytotoxicity of tobacco, which was manifested as twisted heart leaves, severe curling of leaves to the back of the leaves, and severe inhibition of plant height. After the 0.04 mg / kg dichloroquine acid poisoned soil was treated with the pesticide degrading agent of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system), the tobacco seedlings grew normally, and the leaf length and plant height were almost close to the blank control group. After the 0.4 mg / kg dichloroquine acid poisoned soil was treated with the pesticide degrading agent of Example 5 (i.e., starch-montmorillonite hydrothermal carbon activated persulfate reaction system), the tobacco seedlings had a significantly alleviated inhibitory effect on leaf length, leaf width and plant height, indicating that the pesticide degrading agent treatment of Example 5 can alleviate the phytotoxicity of dichloroquine acid to 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 a persulfate; The montmorillonite-hydrothermal carbon composite material is prepared by hydrothermal reaction using montmorillonite and biomass carbon source as raw materials.

2. The soil residual pesticide degradation agent according to claim 1, characterized in that: 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.

3. The soil residual pesticide degradation agent according to claim 1 or 2, characterized in that: The mass ratio of montmorillonite to biomass carbon source is 1:5~3:

1.

4. The soil residual pesticide degradation agent according to claim 1 or 2, characterized in that: The preparation method of the montmorillonite-hydrothermal carbon composite material adopts a hydrothermal method; the hydrothermal reaction temperature of the hydrothermal method is 160-220°C; and / or the hydrothermal reaction time of the hydrothermal method is more than 5 hours; and / or the sucrose-montmorillonite hydrothermal carbon is prepared from montmorillonite and sucrose in a mass ratio of 1:5-3:1, and the starch-montmorillonite hydrothermal carbon is prepared from montmorillonite and starch in a mass ratio of 1:1-2:

1.

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

6. Use of the soil residual pesticide degradation agent according to any one of claims 1 to 5, characterized in that: The specific operation is: add soil residual pesticide degrading agent to the pesticide-containing soil to be treated, mix it thoroughly, and then irrigate water to carry out the pesticide degradation reaction.

7. The use of the soil residual pesticide degradation agent according to claim 6, characterized in that: 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.

8. The use of the soil residual pesticide degradation agent according to claim 6 or 7, 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.

9. The use of the soil residual pesticide degradation agent according to claim 6 or 7, characterized in that: The method of thorough mixing is tillage with a tillage depth of 10 to 20 cm; and / or, the amount of irrigation water added is 1 to 15 kg / m 2 ; and / or, the time for pesticide degradation reaction after irrigation water is not less than 12 hours.

10. The use of the soil residual pesticide degradation agent according to claim 6 or 7, characterized in that: The degradable pesticide is one of the hormone herbicide quinclorac, the protoporphyrinogen oxidase inhibitor herbicides oxadiazon, fomesafen, and sulfentrazone, or a combination of at least two of them.

Images