Modified biochar for repairing soil polluted by long-residual-effect herbicide and preparation method and application of modified biochar

Abstract

The invention provides a preparation method of modified biochar for repairing soil polluted by a long-residual-effect herbicide, which comprises the following steps: (1) crushing, carbonizing and sieving plant straws to obtain plant straw biochar; (2) adding the plant straw biochar obtained in the step (1) into a sodium lignin sulfonate aqueous solution, and uniformly shaking under a constant temperature condition to obtain a mixed solution; (3) adding alkali and epichlorohydrin into the mixed solution obtained in the step (2), stirring at a constant temperature, and adjusting the pH value to obtain a reaction solution; and (4) filtering the reaction solution obtained in the step (3), washing the solid substance with alcohol and water, and drying to obtain the sodium lignin sulfonate modified charcoal. Sodium lignin sulfonate in the modified biochar is uniformly distributed, so that the specific surface area and the alkaline functional group content of the biochar are increased, and the capability of adsorbing long-residual-effect herbicides is improved. The invention further discloses the modified charcoal for repairing the soil polluted by the long-residual-effect herbicide and application of the modified charcoal.

Description

Technical Field

[0001] The present invention belongs to the technical field of contaminated soil remediation, and in particular relates to a modified biochar for remediating soil contaminated by a long-residual herbicide, and a preparation method and application thereof. Background Art

[0002] At present, long-residual herbicides are widely used in agricultural production and play an important role in increasing crop yields and controlling weed growth. However, they are persistent and residual and can exist in the soil for a long time. Long-residual herbicides accumulate in the soil for a long time, which can easily cause damage to subsequent crops. At the same time, they can cause soil compaction, damage the soil microbial structure, reduce soil fertility and other hazards. It is urgent to repair the pollution of long-residual herbicides.

[0003] Biochar is a porous carbonized product formed by thermal cracking of biomass. It has the advantages of developed pores, large specific surface area, rich surface functional groups, and stable physical and chemical properties. These advantages determine that biochar has a strong adsorption capacity, and thus has broad application prospects in the field of herbicide pollution remediation. The degradation process of long-lasting herbicides is extremely long, and the degradation conditions are too harsh. It has the characteristics of long-term, extensive and hidden. Biochar adsorption technology is an extremely efficient way to treat long-lasting herbicide pollution. Compared with other long-lasting herbicide pollution remediation technologies, such as bioenzyme degradation and electrolysis, biochar adsorption technology has many advantages. In terms of use technology, it is simple to operate and has a low threshold for use; in terms of use cost, it has low production cost and is easy to store and transport; in terms of environmental and biological impacts, it is environmentally friendly and harmless to organisms. It is a green and sustainable long-lasting herbicide pollution control technology. Although the inherent characteristics of biochar have ensured its potential for long-lasting herbicide pollution remediation, it still needs to further optimize the structure to improve efficiency.

[0004] As the main by-product of wood hydrolysis industry and papermaking industry, lignin sulfonate is currently less used in my country due to its complex structure and heterogeneous physical and chemical properties. Most of its utilization value is low. Due to its special structure and functional groups, lignin sulfonate has a certain adsorption capacity for metal ions and organic matter.

[0005] In order to solve the above technical problems, the present invention designs a modified biochar for repairing soil contaminated by long-residual herbicides, and a preparation method and application thereof. Summary of the invention

[0006] The present invention provides a modified biochar for repairing soil contaminated by long-residual herbicides, and a preparation method and application thereof, aiming to enhance the ability of biochar to adsorb long-residual herbicides.

[0007] To achieve the above-mentioned object, the present invention provides the following technical scheme: a method for preparing modified biochar for repairing soil contaminated by long-residual herbicides, comprising the following steps: (1) crushing, carbonizing and sieving plant straw to obtain plant straw biochar; (2) adding the plant straw biochar obtained in step (1) to an aqueous solution of sodium lignin sulfonate, and shaking at a constant temperature to obtain a mixed solution; (3) adding alkali and epichlorohydrin to the mixed solution obtained in step (2), stirring at a constant temperature, adjusting the pH, and obtaining a reaction solution; (4) filtering the reaction solution obtained in step (3), washing the solid matter obtained by filtration with alcohol and water, and then drying to obtain biochar modified with sodium lignin sulfonate.

[0008] Based on the above technical solution, in step (1), the plant straw is one or more of corn straw, rice straw, wheat straw, peanut vine or sweet potato vine.

[0009] Based on the above technical solution, the step (1) comprises the following steps: washing and drying the plant straw to constant weight, crushing the plant straw into powder, and passing through a 60-mesh sieve; placing the plant straw powder into a tubular atmosphere furnace, introducing nitrogen at a flow rate of 80 mL / min into the tubular atmosphere furnace, heating the tubular atmosphere furnace to 300° C. to 500° C. at a rate of 10° C. / min, and carbonizing the plant straw powder in an oxygen-free state for 1 h to 2 h under constant temperature conditions; after the tubular atmosphere furnace is cooled to room temperature, passing the carbonized plant straw powder through a 60-mesh sieve to obtain plant straw biochar.

[0010] Based on the above technical solution, in step (2), the concentration of the sodium lignin sulfonate aqueous solution is 25-100 mg / mL, the mass ratio of the plant straw biochar to sodium lignin sulfonate is 1:(1-5), the constant temperature is 25°C, and the shaking time is 5 minutes.

[0011] Based on the above technical solution, in step (3), the mass ratio of the alkali to sodium lignin sulfonate is 1:(2-5), the alkali is sodium hydroxide, potassium hydroxide or barium hydroxide, the mass ratio of epichlorohydrin to sodium lignin sulfonate is (1-2):1, the pH of the reaction solution is adjusted to 10-12, and the constant temperature is 40°C-60°C.

[0012] Based on the above technical solution, in step (4), the alcohol washing and water washing are performed multiple times, and the alcohol is 50% by mass methanol or 70% by mass ethanol.

[0013] Based on the above technical solution, the relative weight gain rate of the biochar modified by sodium lignin sulfonate in step (4) relative to the plant straw biochar in step (1) is 15% to 25%.

[0014] Based on the same inventive concept, the present invention provides a modified biochar for repairing soil contaminated by long-residual herbicides, which is prepared according to the preparation method of the modified biochar for repairing soil contaminated by long-residual herbicides described in any one of the above embodiments.

[0015] Based on the same inventive concept, the present invention provides an application of modified biochar prepared by the method for preparing modified biochar for repairing soil contaminated by long residual herbicides according to any one of the above embodiments in the repair process of soil contaminated by long residual herbicides.

[0016] Based on the above technical scheme, the application of modified biochar in the remediation process of long-residual herbicide contaminated soil includes adding modified biochar to the long-residual herbicide contaminated soil, and the amount of modified biochar added is 0.5%~5% of the mass of the long-residual herbicide contaminated soil.

[0017] Compared with the related art, the beneficial effects of the present invention are as follows: 1. The sodium lignin sulfonate in the modified biochar prepared by the preparation method of the modified biochar for repairing long-residual herbicide pollution provided by the present invention is evenly distributed and forms a good physical and chemical bonding relationship with the modified biochar, thereby increasing the specific surface area and the content of alkaline functional groups of the modified biochar and improving the ability to adsorb long-residual herbicides.

[0018] 2. The preparation method of the modified biochar for repairing long-residual herbicide pollution provided by the present invention is environmentally friendly and pollution-free. The required main raw material, sodium lignin sulfonate, is an industrial by-product. On the basis of improving the adsorption performance of biochar, waste recycling is achieved, which is beneficial to increasing the added value of some industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0020] Figure 1 The present invention is a flow chart of a method for preparing modified biochar for repairing long-residual herbicide pollution. DETAILED DESCRIPTION

[0021] The following will combine the contents in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0023] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0024] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0025] like Figure 1 As shown, the present invention provides a method for preparing modified biochar for repairing soil contaminated by long-residual herbicides, comprising the following steps: S101, crushing, carbonizing, and sieving plant straw to obtain plant straw biochar; S102, adding the plant straw biochar obtained in step S101 to the sodium lignin sulfonate aqueous solution, and shaking at a constant temperature to obtain a mixed solution; S103, adding alkali and epichlorohydrin to the mixed solution obtained in step S102, stirring at a constant temperature, adjusting the pH, and obtaining a reaction solution; S104, filtering the reaction solution obtained in step S103, washing the solid matter obtained by filtration with alcohol and water, and then drying to obtain biochar modified with sodium lignin sulfonate.

[0026] The present invention uses sodium lignin sulfonate to modify plant straw biochar, and the sodium lignin sulfonate is evenly distributed in the obtained modified biochar, and forms a good physical and chemical combination relationship with the modified biochar, thereby increasing the specific surface area and the content of alkaline functional groups of the modified biochar, and improving the ability to adsorb long-residual herbicides. The preparation method is environmentally friendly and pollution-free, and the main raw material sodium lignin sulfonate required is an industrial by-product. On the basis of improving the adsorption performance of biochar, waste recycling is achieved, which is conducive to increasing the added value of some industries.

[0027] Based on the above technical solution, in step S101, the plant straw is one or more of corn straw, rice straw, wheat straw, peanut vine or sweet potato vine. Preferably, the plant straw is corn straw.

[0028] Based on the above technical solution, step S101 includes the following steps: washing and drying the plant straw to constant weight, crushing it into powder, and passing it through a 60-mesh sieve; putting the plant straw powder into a tubular atmosphere furnace, introducing nitrogen at a flow rate of 80 mL / min into the tubular atmosphere furnace, heating the tubular atmosphere furnace to 300°C~500°C at a rate of 10°C / min, and carbonizing it without oxygen at a constant temperature for 1h~2h; after the tubular atmosphere furnace is cooled to room temperature, passing the carbonized plant straw powder through a 60-mesh sieve to obtain plant straw biochar.

[0029] Based on the above technical solution, in step S102, the concentration of the sodium lignin sulfonate aqueous solution is 25-100 mg / mL, the mass ratio of the plant straw biochar to sodium lignin sulfonate is 1:(1-5), the constant temperature is 25°C, and the shaking time is 5 minutes. Preferably, the concentration of the sodium lignin sulfonate aqueous solution is 100 mg / mL.

[0030] Based on the above technical solution, in step S103, the mass ratio of the alkali to sodium lignin sulfonate is 1:(2-5), the alkali is sodium hydroxide, potassium hydroxide or barium hydroxide, the mass ratio of epichlorohydrin to sodium lignin sulfonate is (1-2):1, the pH of the reaction solution is adjusted to 10-12, and the constant temperature is 40°C-60°C. Preferably, the alkali is sodium hydroxide, the mass ratio of the alkali to sodium lignin sulfonate is 2:5, and the mass ratio of epichlorohydrin to sodium lignin sulfonate is 2:1.

[0031] Based on the above technical solution, in step S104, the alcohol washing and water washing are performed multiple times, and the alcohol is 50% by mass methanol or 70% by mass ethanol. Preferably, the alcohol washing and water washing are performed alternately.

[0032] Based on the above technical solution, the relative weight gain rate of the biochar modified by sodium lignin sulfonate in step S104 relative to the plant straw biochar in step (1) is 15% to 25%.

[0033] Based on the same inventive concept, the present invention provides a modified biochar for repairing soil contaminated by long-residual herbicides, which is prepared according to the preparation method of the modified biochar for repairing soil contaminated by long-residual herbicides described in any one of the above embodiments.

[0034] Based on the same inventive concept, the present invention provides an application of modified biochar prepared by the method for preparing modified biochar for repairing soil contaminated by long residual herbicides according to any one of the above embodiments in the repair process of soil contaminated by long residual herbicides.

[0035] Based on the above technical scheme, the application of modified biochar in the remediation process of long-residual herbicide contaminated soil includes adding modified biochar to the long-residual herbicide contaminated soil, and the amount of modified biochar added is 0.5%~5% of the mass of the long-residual herbicide contaminated soil.

[0036] Example 1 The corn straw was washed and dried to constant weight, crushed into powder, and passed through a 60-mesh sieve. The corn straw powder was placed in a tubular atmosphere furnace. Nitrogen was introduced into the tubular atmosphere furnace at a flow rate of 80 mL / min as a reaction atmosphere. The tubular atmosphere furnace was heated to 400°C at a heating rate of 10°C / min, and then heated to 300°C for anaerobic carbonization at a constant temperature for 1.5 h. After the tubular atmosphere furnace was cooled to room temperature, the carbonized corn straw powder was passed through a 60-mesh sieve to obtain corn straw biochar.

[0037] 50 g of sodium lignin sulfonate was dissolved in 500 mL of pure water to obtain a sodium lignin sulfonate aqueous solution with a concentration of 100 mg / mL. 10 g of the corn straw biochar obtained above was added to the sodium lignin sulfonate aqueous solution, and the mixture was shaken at 25°C for 5 min. After shaking, 20 g of sodium hydroxide was added to adjust the pH value of the solution to 12, and 100 g of epichlorohydrin was added. The mixture was stirred at 40°C for 10 min, and the reaction solution was filtered. The solid substance was washed with alcohol three times and water three times, and then dried to obtain biochar A modified with sodium lignin sulfonate.

[0038] Example 2 The preparation method of this embodiment is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in this embodiment, the mass of corn straw biochar added to the sodium lignin sulfonate aqueous solution is 15 g, and biochar B modified with sodium lignin sulfonate is obtained.

[0039] Example 3 The preparation method of this embodiment is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in this embodiment, the mass of corn straw biochar added to the sodium lignin sulfonate aqueous solution is 20 g, and biochar C modified with sodium lignin sulfonate is obtained.

[0040] Furthermore, the modified biochar A, modified biochar B and modified biochar C obtained in Example 1, Example 2 and Example 3 were used to repair the soil contaminated by long residual herbicides. Plants were cultivated in the soil contaminated by long residual herbicides to the three-leaf stage, and the biomass (g) of each plant, the plant height (cm) of each plant and the chlorophyll content (SPAD) of each plant were weighed as quantitative indicators for evaluating the effect of modified biochar on repairing the soil contaminated by long residual herbicides.

[0041] Preferably, the present invention selects three long-residual herbicides as pollution sources, namely atrazine, nicosulfuron, and imazethapyr, and the above three long-residual herbicides are all original drugs. Considering that atrazine and nicosulfuron are mainly used to control broad-leaved weeds in corn fields, which will cause phytotoxicity to broad-leaved crops such as soybeans, and imazethapyr is mainly used to control grass weeds in soybean fields, which will cause phytotoxicity to grass crops such as wheat, therefore, the present invention selects soybeans as the test crop for atrazine and nicosulfuron experiments, and selects wheat as the test crop for imazethapyr experiments.

[0042] Example 4 (1) Atrazine-contaminated soil was prepared and evenly divided into five portions. Soybean plants were directly planted in one portion of the soil and cultivated to the three-leaf stage. Modified biochar A, modified biochar B, modified biochar C, and unmodified biochar were added to the remaining four portions and stirred to make the biochar evenly distributed in the contaminated soil. The mass ratio of biochar to atrazine-contaminated soil was 1:100. Soybean plants were planted and cultivated to the three-leaf stage.

[0043] The biomass of each plant was weighed, the height of each plant was measured, and the chlorophyll content of the leaves was measured.

[0044] Example 5 The method of this embodiment is the same as that of embodiment 4, and the same parts are omitted. The difference from embodiment 4 is that in this embodiment, nicosulfuron-contaminated soil is prepared.

[0045] Example 6 The method of this embodiment is the same as that of embodiment 4, and the same parts are omitted. The difference from embodiment 4 is that, in this embodiment, imidacloprid is prepared to contaminate soil, and wheat plants are planted and cultivated to the three-leaf stage.

[0046] Comparative Example 1 Soybean plants were planted in clean soil and cultivated to the three-leaf stage. The biomass of each plant was weighed, the plant height of each plant was measured, and the chlorophyll content of the leaves was measured.

[0047] Comparative Example 2 Wheat plants were planted in clean soil and cultivated until the three-leaf stage. The biomass of each plant was weighed, the plant height of each plant was measured, and the chlorophyll content of the leaves was measured.

[0048] Furthermore, in order to eliminate errors caused by cultivation problems, the data measured in the above embodiments are all presented in the form of average values.

[0049] Table 1 Soybean plant data results in Example 4 and Comparative Example 1

[0050] Table 2 Soybean plant data results in Example 5 and Comparative Example 1

[0051] Table 3 Wheat plant data results in Example 6 and Comparative Example 2

[0052] Tables 1 to 3 show that the plants cultivated in the contaminated soils with the addition of modified biochar A, modified biochar B and modified biochar C as well as unmodified biochar were all relieved from the toxic effects of long-residual herbicides, and all plant indicators were restored compared with those in the contaminated soil group; among them, the plants cultivated in the contaminated soils with the addition of modified biochar A, modified biochar B and modified biochar C were more significantly relieved from the toxic effects of long-residual herbicides, and all plant indicators were more obviously restored compared with those cultivated in the contaminated soils with the addition of unmodified biochar.

[0053] Through comparative analysis of various indicators of the above plants, it can be concluded that the modified biochar proposed in the present invention has a good repair effect on soil contaminated by long-residual herbicides.

[0054] In summary, the modified biochar material proposed in the present invention uses sodium lignin sulfonate solution to modify biochar, which improves the adsorption and stability of long-residual herbicides in contaminated soil, can effectively reduce the toxic effects of long-residual herbicide-contaminated soil on subsequent crops, and effectively repair long-residual herbicide-contaminated soil.

[0055] The present invention is described above by way of examples, but the present invention is not limited to the above specific embodiments, and any changes or modifications made based on the present invention belong to the scope of protection claimed by the present invention.

Claims

1. A method for preparing modified biochar for repairing soil contaminated by long-residual herbicides, characterized in that: The following steps are involved: (1) crushing, carbonizing and sieving plant straw to obtain plant straw biochar; (2) adding the plant straw biochar obtained in step (1) into the sodium lignin sulfonate aqueous solution, and shaking at a constant temperature to obtain a mixed solution; (3) adding alkali and epichlorohydrin to the mixed solution obtained in step (2), stirring at a constant temperature, and adjusting the pH to obtain a reaction solution; (4) The reaction solution obtained in step (3) is filtered, and the solid matter obtained by filtration is washed with alcohol and water and then dried to obtain biochar modified with sodium lignin sulfonate.

2. The method for preparing modified biochar for repairing soil contaminated by long-residual herbicides according to claim 1, characterized in that: In the step (1), the plant straw is one or more of corn straw, rice straw, wheat straw, peanut vine or sweet potato vine.

3. The method for preparing modified biochar for repairing soil contaminated by long-residual herbicides according to claim 1, characterized in that: The step (1) comprises the following steps: Wash the plant straw, dry it to constant weight, grind it into powder, and pass it through a 60-mesh sieve; The plant straw powder is placed in a tubular atmosphere furnace, nitrogen is introduced into the tubular atmosphere furnace at a flow rate of 80 mL / min, the tubular atmosphere furnace is heated to 300°C~500°C at a heating rate of 10°C / min, and oxygen-free carbonization is performed at a constant temperature for 1h~2h; After the tubular atmosphere furnace is cooled to room temperature, the carbonized plant straw powder is passed through a 60-mesh sieve to obtain plant straw biochar.

4. The method for preparing modified biochar for repairing soil contaminated by long-residual herbicides according to claim 1, characterized in that: In the step (2), the concentration of the sodium lignin sulfonate aqueous solution is 25-100 mg / mL, the mass ratio of the plant straw biochar to sodium lignin sulfonate is 1:(1-5), the constant temperature is 25°C, and the shaking time is 5 minutes.

5. The method for preparing modified biochar for repairing soil contaminated by long-residual herbicides according to claim 1, characterized in that: In the step (3), the mass ratio of the alkali to sodium lignin sulfonate is 1:(2-5), the alkali is sodium hydroxide, potassium hydroxide or barium hydroxide, the mass ratio of epichlorohydrin to sodium lignin sulfonate is (1-2):1, the pH of the reaction solution is adjusted to 10-12, and the constant temperature is 40°C-60°C.

6. The method for preparing modified biochar for repairing soil contaminated by long-residual herbicides according to claim 1, characterized in that: In the step (4), the alcohol washing and water washing are performed multiple times, and the alcohol is 50% by mass methanol or 70% by mass ethanol.

7. The method for preparing modified biochar for remediating soil contaminated by long-residual herbicides according to claim 1, characterized in that: The relative weight gain rate of the biochar modified by sodium lignin sulfonate in step (4) relative to the plant straw biochar in step (1) is 15% to 25%.

8. A modified biochar for remediation of soil contaminated by long-residual herbicides, characterized in that: The modified biochar is prepared according to the method for preparing the modified biochar for repairing soil contaminated by long-residual herbicides according to any one of claims 1 to 7.

9. Use of the modified biochar prepared by the method for preparing modified biochar for remediation of soil contaminated by long residual herbicides according to any one of claims 1 to 7 in the remediation of soil contaminated by long residual herbicides.

10. The use according to claim 9, characterized in that: The method comprises adding modified biochar to soil contaminated by long-residual herbicides, wherein the amount of the modified biochar added is 0.5% to 5% of the mass of the soil contaminated by the long-residual herbicide.

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