An iron-based improver for rapidly degrading pesticides in farmland soil and its application method

Abstract

The present invention discloses a kind of iron-based amendment for rapidly degrading farmland soil pesticide and its application method, the iron-based amendment includes 85 95 parts of industrial micron iron powder and 5 15 parts of nitrogen and sulfur doped biochar.The application method of the iron-based amendment is: first, it is broadcasted to the surface layer of farmland soil, ploughed and mixed, and the concentration of the iron-based amendment is 0.25 1.0 g / kg; The farmland is then irrigated, the film is covered to keep moisture and isolate oxygen, and the film is peeled off after 5 7 days of maintenance; After the water is naturally dried, the crop seeds are sown into the soil, and water and fertilizer management is carried out to harvest.The iron-based amendment of the present invention can significantly reduce the pesticide content in farmland soil and subsequent crops, quickly reduce the pesticide damage of soil residual pesticides to crops, and soil remediation efficiency is high.

Description

Technical Field

[0001] The present invention relates to the technical field of farmland soil pollution remediation, and in particular to an iron-based improver for rapidly degrading farmland soil pesticides and an application method thereof. Background Art

[0002] Currently, soil remediation technologies include the use of biochar, compost, zeolite, and other stabilizers, leaching with chemical agents such as ferric chloride, in-situ electrokinetic remediation, and phytoremediation with microorganisms. However, these technologies are labor-intensive, costly, and time-consuming, making them difficult to implement on large-scale organically contaminated farmland. Furthermore, they are prone to secondary pollution, soil structural damage, and soil fertility degradation.

[0003] Zero-valent iron (ZVI) is highly reactive and can be used as a remediation material to effectively remove pollutants such as organochlorine and heavy metals from the environment. Iron is also the fourth most abundant element in the Earth's crust and the most abundant transition metal on Earth; therefore, ZVI is considered an environmentally friendly soil conditioner.

[0004] For example, the invention patent application with application publication number CN106800939A discloses a remediation agent for treating soil heavy metal complex pollution. The remediation agent comprises: 6-8 parts modified nanocarbon black, 2-5 parts sodium bentonite-loaded nano-zero-valent iron, 1-2 parts phosphate mineral, and 5-10 parts decomposed agricultural and forestry waste. The preparation method is as follows: (1) crushing the phosphate mineral and decomposed agricultural and forestry waste into a powder with a particle size of 100-200 mesh and drying for later use; (2) mixing the modified nanocarbon black, phosphate mineral, sodium bentonite-loaded nano-zero-valent iron, and decomposed agricultural and forestry waste according to the formula, and stirring in a sealed container to prepare the remediation agent for treating soil heavy metal complex pollution.

[0005] Nano-zero-valent iron is used in industrial soil remediation at concentrations as high as 10-20g / kg. However, as research deepens, increasing evidence suggests that nano-zero-valent iron can have toxic effects on various organisms due to size effects. For example, a report in which Typha latifolia and Populus seedlings were incubated in suspensions of varying concentrations of nano-zero-valent iron showed that additions above 200mg / kg slowed their growth and caused symptoms such as yellowing of their leaves.

[0006] Therefore, it is necessary to establish a low-cost nano-zero-valent iron application technology for rapid repair of pesticide pollution in farmland, which can significantly reduce the pesticide content in farmland soil and subsequent crops, quickly reduce the damage of residual pesticides in the soil to crops, and have high soil remediation efficiency. Summary of the Invention

[0007] The present invention provides an iron-based modifier for rapidly degrading pesticides in farmland soil and an application method thereof. The method can significantly improve the rapid repair effect of pesticides in pesticide-contaminated farmland soil in a short period of time, reduce the harm of pesticides to subsequent crops, reduce pesticide residues in agricultural products, ensure crop growth, and promote agricultural safety production and sustainable utilization of agricultural environmental resources.

[0008] The purpose of the present invention is to provide an iron-based improver for rapidly degrading pesticides in farmland soil as a method for controlling soil pesticide pollution.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for preparing an iron-based modifier, the preparation method comprising the following steps:

[0011] S1: 1-10g of biomass raw material with a dry weight is impregnated with 100-500ml of 1-5g / L thiourea aqueous solution at a stirring speed of 200-800rpm / min for 2-10h. After stirring evenly, the impregnated mixed slurry is placed in a refrigerator to freeze. The frozen slurry is placed in a freeze dryer to remove excess water to obtain a biochar precursor. The dried biochar precursor is placed in an atmosphere furnace and preheated to 700-900℃ at a heating rate of 1-20℃ / min using nitrogen as a protective gas and maintained for 2-3h. Finally, a black solid is obtained after natural cooling under a nitrogen atmosphere. The solid is washed several times with deionized water and freeze-dried to obtain a nitrogen-sulfur co-doped biochar material.

[0012] S2: industrial iron powder and nitrogen-sulfur co-doped biochar powder are mixed evenly according to weight proportions and placed in a zirconia ball mill jar, zirconia beads are added to the zirconia ball mill jar, and then the zirconia ball mill jar is placed in a planetary ball mill, and ball milled at a speed of 400 r / min for 10 hours to obtain an iron-based modifier.

[0013] Preferably, as a better embodiment, the weight ratio of the industrial iron powder and the nitrogen-sulfur co-doped biochar powder is 85-95:5-15.

[0014] Preferably, as a preferred embodiment, the method for preparing the nitrogen-sulfur co-doped biochar material comprises the following steps:

[0015] Another object of the present invention is to provide an application method of an iron-based amendment for rapidly degrading pesticides in farmland soil, comprising the following steps:

[0016] (1) Sprinkle the iron-based amendment onto the surface of the farmland soil and perform mechanical plowing to fully mix the iron-based amendment with the soil. The concentration of the iron-based amendment is 0.25-1.0 g / kg.

[0017] (2) The farmland is then irrigated and covered with a film to retain moisture and isolate oxygen. The film is removed after 5-7 days of maintenance. After the water has dried naturally, the crop seeds are sown into the soil and water and fertilizer management is carried out until harvest.

[0018] Furthermore, as a preferred embodiment, the pesticides include one or more of neonicotinoid pesticides, amide pesticides, dinitroaniline pesticides, organophosphorus pesticides, and the like.

[0019] Furthermore, as a preferred embodiment, the concentration of the iron-based modifier is 0.25-1.0 g / kg, and the tillage depth is 15-20 cm.

[0020] Furthermore, as a preferred embodiment, the irrigation refers to the soil moisture content reaching more than 60%, and the film covering measure refers to covering the soil surface with agricultural film.

[0021] The present invention has found in experiments that applying iron-based amendments to farmland soil can significantly reduce the pesticide content in farmland soil and subsequent crops, quickly reduce the damage of residual pesticides in the soil to crops, and improve soil remediation efficiency and crop production efficiency.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The nitrogen-sulfur doped biochar iron-based improver of the present invention can improve the reactivity of zero-valent iron by doping biochar with nitrogen and sulfur, and achieve rapid degradation of pesticides in the soil. The effect is significantly higher than that of the iron-based improver synthesized without biochar doping. After 5-7 days of improvement, the pesticide content in the farmland soil is significantly and rapidly reduced.

[0024] (2) The method of the present invention applies an iron-based amendment to pesticide-contaminated farmland soil, and it is found that there is an interaction between the iron-based amendment and crops. It can not only significantly reduce the content of pesticides in organically contaminated farmland and crops, and slow down the damage to subsequent crops, but also ensure the increase of crop yield, improve soil remediation efficiency, and improve crop production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Fresh weight and total iron content of corn seedlings in acetochlor-contaminated soil treated with different iron-based amendments in Example 1 and Comparative Example 1.

[0026] Figure 2 The residual amounts of acetochlor in the soil and corn seedling leaves treated with different iron-based amendments in Example 1 and Comparative Example 1.

[0027] Figure 3 Fresh weight and total iron content of lettuce in soil contaminated with thiamethoxam under different application concentrations of the iron-based amendment in Example 2.

[0028] Figure 4 Thiamethoxam residues in soil and lettuce leaves treated with different application concentrations of the iron-based amendment in Example 2.

[0029] Figure 5 The fresh weight of lettuce and the residue of thiamethoxam under Example 2, Comparative Example 2 and commercial nano zero-valent iron treatment. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with specific embodiments. The following are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto.

[0031] Example 1

[0032] 10 g of rice straw with a dry weight was soaked and mixed with 500 ml of a 5 g / L thiourea aqueous solution at a stirring speed of 500 rpm / min for 8 hours. After stirring evenly, the soaked mixed slurry was placed in a refrigerator and frozen. The frozen slurry was placed in a freeze dryer to remove excess water to obtain a biochar precursor.

[0033] The dried biochar precursor was further placed in an atmosphere furnace, and preheated to 900°C at a heating rate of 10°C / min with nitrogen as the protective gas and maintained for 2 hours. Finally, a black solid was obtained after natural cooling under a nitrogen atmosphere. The solid was washed several times with deionized water and freeze-dried to obtain nitrogen-sulfur co-doped biochar material.

[0034] Industrial iron powder and nitrogen-sulfur co-doped biochar powder were mixed uniformly in a weight ratio of 90:10 and placed in a zirconia ball mill. Zirconia beads were added to the zirconia ball mill. The zirconia ball mill was then placed in a planetary ball mill and ball milled at a speed of 400 r / min for 10 hours to obtain an iron-based modifier.

[0035] This example uses artificial acetochlor exposure at a concentration of 5 mg / kg. An iron-based amendment was applied to the surface of the artificially treated soil, followed by tillage to thoroughly mix the iron-based amendment with the soil. The concentration of the iron-based amendment was 1.0 g / kg. The field was then irrigated and covered with a film to retain moisture and isolate oxygen. The film was removed after seven days of curing. After the water dried naturally, corn seeds were sown into the soil. The growth of the corn and the amount of acetochlor residue in the soil and plants were observed. The total iron in the soil was then digested using microwaves and measured by atomic absorption spectrometry.

[0036] Example 2

[0037] 5 g of leaf powder with a dry weight was soaked and mixed with 500 ml of a 5 g / L sulfamide aqueous solution at a stirring speed of 600 rpm / min for 10 h. After stirring evenly, the soaked mixed slurry was placed in a refrigerator and frozen. The frozen slurry was placed in a freeze dryer to remove excess water to obtain a biochar precursor.

[0038] The dried biochar precursor was further placed in an atmosphere furnace, and preheated to 700°C at a heating rate of 15°C / min using nitrogen as a protective gas and maintained for 1.5 hours. Finally, a black solid was obtained after natural cooling under a nitrogen atmosphere. The solid was washed several times with deionized water and freeze-dried to obtain nitrogen-sulfur co-doped biochar material.

[0039] Industrial iron powder and nitrogen-sulfur co-doped biochar powder were mixed uniformly in a weight ratio of 85:15 and placed in a zirconia ball mill. Zirconia beads were added to the zirconia ball mill. The zirconia ball mill was then placed in a planetary ball mill and ball milled at a speed of 300 r / min for 8 hours to obtain an iron-based modifier.

[0040] This example used artificial thiamethoxam poisoning at a concentration of 5 mg / kg. An iron-based amendment was applied to the surface of the soil treated with acetochlor and then plowed to thoroughly mix the iron-based amendment with the soil. The iron-based amendment was applied at concentrations of 0.10, 0.25, and 0.50 g / kg, respectively. The fields were then irrigated and covered with a film to retain moisture and isolate oxygen. The film was removed after five days of curing. After the water dried naturally, lettuce seeds were sown into the soil. The growth of the lettuce and the amount of thiamethoxam residue in the soil and plants were observed. The total iron in the soil was then digested by microwave and measured by atomic absorption spectrometry.

[0041] Comparative Example 1

[0042] 10 g of dried rice straw was placed in an atmosphere furnace, and preheated to 900 °C at a heating rate of 10 °C / min using nitrogen as the protective gas and maintained for 2 h. Finally, a black solid was obtained after natural cooling under a nitrogen atmosphere, that is, undoped biochar material.

[0043] Industrial iron powder and undoped biochar powder were mixed in a weight ratio of 90:10 and placed in a zirconia ball mill. Zirconia beads were added to the zirconia ball mill. The zirconia ball mill was then placed in a planetary ball mill and ball milled at a speed of 400 r / min for 10 h to obtain an undoped control iron-based modifier.

[0044] In this example, artificial acetochlor was used for soil treatment at a concentration of 5 mg / kg. A control iron-based amendment was applied to the surface of the artificially treated soil, followed by tillage to thoroughly mix the iron-based amendment with the soil. The concentration of the iron-based amendment was 1.0 g / kg. The field was then irrigated and covered with a film to retain moisture and isolate oxygen. The film was removed after seven days of curing. After the water dried naturally, corn seeds were sown into the soil. The growth of the corn and the amount of acetochlor residue in the soil and plants were observed. The total iron in the soil was then digested by microwave and measured by atomic absorption spectrometry.

[0045] Comparative Example 2

[0046] Place 10g of dried leaf powder in an atmosphere furnace, use nitrogen as the protective gas, preheat to 700℃ at a heating rate of 15℃ / min and maintain for 1.5h, and finally cool naturally under a nitrogen atmosphere to obtain a black solid. Wash it several times with deionized water and freeze-dry it to obtain undoped biochar material.

[0047] Industrial iron powder and undoped biochar powder were mixed in a weight ratio of 85:15 and placed in a zirconia ball mill. Zirconia beads were added to the zirconia ball mill. The zirconia ball mill was then placed in a planetary ball mill and ball milled at a speed of 300 r / min for 8 h to obtain an undoped control iron-based modifier.

[0048] In this example, artificial thiamethoxam was used for soil treatment at a concentration of 5 mg / kg. An iron-based amendment was applied to the surface of the artificially acetochlor-treated soil and plowed to thoroughly mix the iron-based amendment with the soil. The concentrations of the iron-based amendment were 0.10, 0.25, and 0.50 g / kg, respectively. The fields were then irrigated and covered with a film to retain moisture and isolate oxygen. The film was removed after five days of curing. After the water dried naturally, lettuce seeds were sown into the soil. The growth of the lettuce and the amount of thiamethoxam residue in the soil and plants were observed. The total iron in the soil was then digested by microwave and measured by atomic absorption spectrometry.

[0049] The experimental results are as follows Figure 1-2 As shown, in Example 1 and Comparative Example 1, 1.0 g / kg of the iron-based modifier was applied to the acetochlor-contaminated farmland. It was found that there was an interaction between the iron-based modifier and the corn plants, which not only ensured the improvement of the growth ability of the corn and slowed down the occurrence of acetochlor damage, but also significantly reduced the acetochlor content in the soil and corn plants.

[0050] The experimental results are as follows Figure 3-4As shown, in Example 2, different concentrations of iron-based amendments were applied to farmland soil contaminated with thiamethoxam. It was found that iron-based amendments at a dosage of 0.25 g / kg or more not only ensured an increase in lettuce yield, but also significantly reduced the content of thiamethoxam in organically contaminated farmland soil and lettuce; and the increase in lettuce yield and the reduction in thiamethoxam content were positively correlated with the concentration of the iron-based amendment.

[0051] This example uses commercial nano zero-valent iron and undoped control iron-based modifier (Comparative Example 2) as the control group of the iron-based modifier of the present invention (Example 2). The dosage concentration of the three is 0.5g / kg, and the rest of the contents are the same. The experimental results are shown in Figure 2. Figure 5 As shown, the iron-based amendment of Example 2 was applied to farmland soil contaminated with the pesticide thiamethoxam. It was found that the iron-based amendment significantly improved lettuce yield and reduced the content of thiamethoxam in organic pesticide-contaminated farmland soil and crops, compared to the pesticide control, commercial nano-zero-valent iron, and undoped control iron-based amendment (Comparative Example 2). These test results demonstrate that the iron-based amendment can simultaneously degrade farmland soil pesticides and promote crop growth, and its performance is excellent, significantly better than commercial nano-zero-valent iron and undoped control iron-based amendments.

[0052] Based on the ideal embodiments of the present invention, and with reference to the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing an iron-based conditioner for rapidly degrading pesticides in farmland soil, characterized in that: The following steps are involved: S1: Preparation of nitrogen-sulfur co-doped biochar: adding biomass raw material to an aqueous solution of nitrogen-sulfur compounds, fully impregnating, and then freezing in a refrigerator; placing the frozen slurry in a freeze dryer to remove excess water to obtain a biochar precursor; placing the dried biochar precursor in an atmosphere furnace for pyrolysis to obtain a black solid, which is then washed several times with deionized water and freeze-dried to obtain a nitrogen-sulfur co-doped biochar material; Preparation of S2 iron-based modifier: industrial micron iron powder and nitrogen-sulfur co-doped biochar are mixed according to the mass ratio, mixed evenly and placed in a ball mill jar to which zirconia beads have been added. The ball mill jar is then placed in a planetary ball mill and ball milled at a speed of 300-400 r / min for 8-20 h to obtain the iron-based modifier; In step S1, 1-10 g of biomass raw material with a dry weight is soaked and mixed with 100-500 ml of an aqueous solution of a nitrogen-containing sulfur compound with a concentration of 1-5 g / L; In the step S2, the content of industrial micron iron powder is 85-95 parts, and the content of nitrogen-sulfur co-doped biochar is 5-15 parts. After the two are mixed, they are ball milled at a speed of 300-400 r / min for 8-20 hours.

2. The method for preparing an iron-based amendment for rapidly degrading farmland soil pesticides according to claim 1, characterized in that: The biomass raw materials in step S1 include crop straw, forestry waste, newspapers, and waste paper.

3. The method for preparing an iron-based amendment for rapidly degrading farmland soil pesticides according to claim 1, characterized in that: The nitrogen-sulfur compound in step S1 includes but is not limited to thiourea and sulfamide.

4. The method for preparing an iron-based amendment for rapidly degrading farmland soil pesticides according to claim 1, characterized in that: In the step S1, the stirring speed is 200-800 rpm / min, and the stirring time is 2-10 h; after stirring evenly, the impregnated mixed slurry is placed in a refrigerator and frozen; the frozen slurry is placed in a freeze dryer to remove excess water to obtain a biochar precursor.

5. The method for preparing an iron-based amendment for rapidly degrading farmland soil pesticides according to claim 1, characterized in that: In step S1, the dried biochar precursor is placed in an atmosphere furnace, and preheated to 700-900°C at a heating rate of 1-20°C / min using nitrogen as a protective gas and maintained for 2-3 hours. Finally, a black solid is obtained after natural cooling under a nitrogen atmosphere. The solid is washed several times with deionized water and freeze-dried to obtain a nitrogen-sulfur co-doped biochar material.

Images