Corn-sorghum straw pyroligneous acid and preparation method and application thereof

Abstract

The application discloses corn-highland straw wood vinegar and a preparation method and application thereof, and belongs to the technical field of pesticide synergists, and the preparation method comprises the following steps: (1) corn straw and highland straw are mixed, crushed, dried, preheated and cracked, and then subjected to solid decomposition at a temperature of 300-600 DEG C to obtain a crude wood vinegar; (2) the crude wood vinegar is repeatedly stored by freezing and thawing for 6 months, then filtered and distilled, the light components are reserved, and the heavy components are removed; (3) the light components are extracted by butyl triphosphate and diethyl ether in sequence, then the extract is subjected to molecular distillation to evaporate the solvent, and the wood vinegar is obtained. The application further discloses the wood vinegar prepared by the preparation method and application of the wood vinegar in a pesticide synergist. The wood vinegar obtained by the application mainly plays a stomach poison, contact killing and avoidance role on the target, and can provide a further idea for developing a low-toxicity and environment-friendly plant source compound pesticide.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pesticide synergists, and particularly relates to a corn-sorghum straw wood vinegar and a preparation method and application thereof. BACKGROUND

[0002] Wood vinegar, also known as plant acid, is an organic mixture obtained by condensing and separating the gas derived from the dry distillation of biomass such as wood. Its main components include phenols, acids, alcohols and other organic substances and trace elements, as well as toxic and harmful substances such as tar. The composition of wood vinegar varies with the raw material, and the functionality also varies accordingly.

[0003] Currently, wood vinegar can be applied in various fields, such as fertilizers, pesticides, biodiesel, wood preservatives, leather tanning agents, fiber dyes, food additives, etc. (Wang Jiaqing, 2020; Li Zhanchao, 2019). In agriculture, studies have shown that wood vinegar can promote plant growth, enhance plant disease resistance and adaptability, and has a significant effect on the cultivation of fruit trees, vegetables, flowers and other crops, indicating that wood vinegar has the potential to be developed as a plant growth regulator.

[0004] In the study of the effect of apricot shell wood vinegar on peach aphids, Yu Hailin (2021) found that high-concentration wood vinegar had a toxic effect on peach aphids. Cui Yi et al. (2016) found that pine wood vinegar had a toxic effect on yellow mealworm larvae, with a mortality rate of 56.67% on the 22nd day. The above shows that wood vinegar also has the potential to be developed as an insecticide. However, there are few reports on the development of wood vinegar as a synergist for insecticides, and the raw material for preparing wood vinegar directly affects the quality and yield of wood vinegar. Currently, all patents developed for agricultural applications of wood vinegar do not specify the composition of wood vinegar, but only generally refer to wood vinegar.

[0005] Therefore, how to provide a preparation method of wood vinegar that can be used as a synergist for insecticides, while specifying its composition, is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0006] To solve the above technical problems, the present application provides a corn-sorghum straw wood vinegar and a preparation method and application thereof in compounded insecticides.

[0007] To achieve the above purpose, the present application provides the following technical solutions:

[0008] A preparation method of corn-sorghum straw wood vinegar, comprising the following steps:

[0009] (1) corn stalks and sorghum stalks are mixed, crushed and dried, preheated and pyrolyzed, and then heated to 300-600℃ for solid decomposition to obtain a crude wood vinegar liquid;

[0010] (2) the crude wood vinegar liquid is freeze-thawed, filtered, and then distilled to retain light components and remove heavy components;

[0011] (3) the light components are extracted with butyl trisphosphate and diethyl ether in sequence, and then the extract is subjected to molecular distillation to evaporate the solvent to obtain the wood vinegar liquid.

[0012] Beneficial effects: the method greatly improves the content of organic phenol in the product wood vinegar liquid, and the content of organic phenol can reach 20-50%.

[0013] Preferably, the mass ratio of corn stalks to sorghum stalks in step (1) is 1:1.

[0014] The preheating and pyrolysis is heating at a rate of 5℃ / min to a temperature of 150-300℃ for 0.5h.

[0015] The continuous heating rate is 10℃ / min.

[0016] Beneficial effects: in the preheating and pyrolysis stage, the thermal decomposition reaction of the material is relatively obvious, and the chemical composition begins to change, and unstable components such as hemicellulose are decomposed into CO2, CO and a small amount of acetic acid and other substances.

[0017] Preferably, the solid decomposition time in step (1) is 0.5h.

[0018] Beneficial effects: under the above solid decomposition conditions, the content of organic phenol and organic acid that can be effectively utilized in the crude wood vinegar liquid can be improved.

[0019] The storage time in step (2) is 6 months.

[0020] The freeze-thawing frequency is three times, and each freeze-thawing time is 2 months.

[0021] The filtration is through a 0.22 micron flat membrane.

[0022] The distillation is carried out at 90-105℃ using a molecular distillation device.

[0023] Beneficial effects: the above distillation method can concentrate the wood vinegar liquid and remove water.

[0024] A corn-sorghum stalk wood vinegar liquid prepared by the preparation method, the content of organic phenol in the corn-sorghum stalk wood vinegar liquid is 20-50%.

[0025] Beneficial effects: the present application quantifies the organic phenol content, effectively quantifies the synergistic effect of wood vinegar, and ensures the synergistic effect of wood vinegar.

[0026] Application of wood vinegar in insecticide synergist.

[0027] A corn-sorghum straw wood vinegar-based compound insecticide, comprising the wood vinegar of claim and an insecticide.

[0028] The mass ratio of the wood vinegar to the insecticide is (2-21):1.

[0029] Beneficial effects: under the above addition ratio, the co-toxicity coefficient can reach 145.99-201.39, and the synergistic effect on insecticides is remarkable.

[0030] Preferably, the insecticide comprises one of deltamethrin, chlorbenzuron, indoxacarb, buprofezin and high-efficiency cypermethrin.

[0031] Preferably, the following raw materials are included in parts by weight:

[0032] Deltamethrin 1 part and wood vinegar 10 parts, under this ratio, the co-toxicity coefficient reaches 201.39;

[0033] Or,

[0034] Indoxacarb 3 parts and wood vinegar 7 parts, under this ratio, the co-toxicity coefficient reaches 167.32;

[0035] Or,

[0036] Buprofezin 1 part and wood vinegar 21 parts, under this ratio, the co-toxicity coefficient reaches 145.99;

[0037] Or,

[0038] High-efficiency cypermethrin 2 parts and wood vinegar 7 parts, under this ratio, the co-toxicity coefficient reaches 176.98;

[0039] Or,

[0040] Chlorbenzuron 1 part and wood vinegar 15 parts, under this ratio, the co-toxicity coefficient reaches 175.33.

[0041] The application discloses corn-sorghum straw wood vinegar and a preparation method and application thereof. The application refines wood vinegar generated in the production process of mixed straw (corn:sorghum = 1:1) biochar, and develops the wood vinegar as an environment-friendly plant source pesticide synergist with insecticidal synergistic effect on the premise of determining the composition of the wood vinegar. In the process of refining the wood vinegar, the toxic and harmful substances such as tar entrained in the production are removed, and the wood vinegar has the characteristics of low toxicity, harmlessness and environmental friendliness. In addition, the application is a composition with a clear composition extracted from the mixed straw (corn:sorghum = 1:1) wood vinegar, wherein the total content of organic phenol in the obtained wood vinegar is 20-50%, the wood vinegar can be used as a synergist of a chemical insecticide stable under acidic conditions, and the purpose of reducing pesticide and increasing efficiency can be achieved. The target mainly plays stomach poisoning, contact killing and repellent action, and can provide further ideas for developing low-toxicity and environment-friendly plant source compound insecticides. BRIEF DESCRIPTION OF DRAWINGS

[0042] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application, and are used to interpret the application and its description, and do not constitute improper limitations to the present application. In the drawings:

[0043] Figure 1 A total ion current chromatogram of the refined wood vinegar obtained in Example 1 is analyzed by GC-MS. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0045] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to specific implementation manners.

[0046] Unless otherwise specified, the raw materials in the present application are obtained by market purchase.

[0047] Example 1

[0048] A preparation method of corn-sorghum straw wood vinegar comprises the following steps:

[0049] (1) corn straw and sorghum straw are mixed in a mass ratio of 1:1, and are crushed, then the material in a reaction kettle is heated to 150 DEG C by external heating, water in the material is evaporated for drying, and the chemical composition of the material is almost unchanged;

[0050] (2) Preheating and cracking stage: continue to use external heating to make the temperature of the material in the reactor 150-300℃ at a heating rate of 5℃ / min;

[0051] (3) Solid decomposition stage: continue to use external heating to make the temperature of the material in the reactor 300-600℃ at a heating rate of 10℃ / min, to obtain a crude wood vinegar liquid;

[0052] (4) Low-temperature precipitation stage: store the crude wood vinegar liquid in a storage tank at low temperature for 6 months, during which time it is repeatedly frozen and thawed 3 times, each time for 2 months, then filter the frozen and thawed crude wood vinegar liquid through a 0.22 micron flat membrane, and then distill the filtered crude wood vinegar liquid using a molecular distillation device at 90-105℃, retaining the light components and removing the heavy components;

[0053] (5) Extract the obtained light components with butyl trisphosphate and diethyl ether, then evaporate the diethyl ether from the extract using a rotary evaporator, and the remaining components are the wood vinegar liquid.

[0054] Technical effects

[0055] The composition of the obtained wood vinegar liquid is identified by GC-MS method.

[0056] Gas chromatography conditions: HP-5 elastic capillary column (30mm x 0.25mm x 0.25μm) is selected, high-purity helium gas (purity ≥ 99.999%) is used as the carrier gas, the injection port temperature is 280℃, the column temperature is 60℃, the temperature is kept constant for 1min, then increased to 120℃ at a rate of 6.0℃ / min, and then increased to 280℃ at a rate of 10.0℃ / min, and kept for 5min; split injection, injection ratio is 10:1, carrier gas flow rate is 1.0mL / min, injection volume is 1μL.

[0057] Mass spectrometry conditions: EI source, electron energy 70eV, ion source temperature 250℃, mass spectrometry scan range 20-750amu, mass spectrometry standard library NIST library.

[0058] The results of the main chemical components in the wood vinegar liquid are shown in Table 1:

[0059] Table 1

[0060]

[0061]

[0062] It can be seen that after the refining treatment of steps (4)-(5), the organic phenol peak area in the total ion chromatogram is integrated and calculated, and the content of organic phenol in the obtained wood vinegar liquid is determined to be 40-50%, which has obvious synergistic effect on insecticides. Figure 1

[0063] ​Comparative Example 1

[0064] A method for preparing wood vinegar, which is different from Example 1 in that only corn stalks are used as raw materials. The organic phenol content in the refined wood vinegar obtained is 10-20%.

[0065] Comparative Example 2

[0066] A method for preparing wood vinegar, which is different from Example 1 in that only sorghum stalks are used as raw materials. The organic phenol content in the refined wood vinegar obtained is 20-30%.

[0067] Comparative Example 3

[0068] A method for preparing wood vinegar, which is different from Example 1 in that steps (4) and (5) are not included, and only the crude wood vinegar obtained in step (3) is used as the final product. The product obtained contains a large amount of tar and other polycyclic aromatic hydrocarbon components, which does not meet the pesticide registration standards and cannot be used in agriculture.

[0069] Example 4

[0070] Application of corn-sorghum stalk wood vinegar in a compound insecticide, including the following steps:

[0071] Wood vinegar combined toxicity determination:

[0072] 1. Test insects

[0073] Sensitive population, provided by Keyun Biology, domesticated for one generation in a rearing room with a temperature of 25±1℃, humidity of 60%-70%, and light L / D=14h / 10h. The hatched larvae were fed with fresh pak choi grown in the laboratory. When the pak choi was eaten by 1 / 5, another plate of fresh pak choi was placed close to it, and the larvae would automatically crawl to the fresh pak choi for feeding. The mature larvae pupated on the edge of the plate and the stems. After 2-3 days of pupation, the pupae were picked out and placed in the adult rearing cage. After emergence, the adults were supplemented with 10% honey water for nutrition. When they started to lay eggs, they were placed in pak choi for egg collection. New pak choi was replaced every 24 hours, and the eggs were labeled. The eggs hatched into larvae after 3-4 days. During the feeding period, the temperature and humidity conditions were ensured, diseases were prevented, and the environment was kept clean. The feeding tools were disinfected regularly, and the feeding amount of the third instar larvae was observed to prevent the larvae from migrating due to insufficient food. No insecticides were used during the feeding period.

[0074] 2. Test agents

[0075] Wood vinegar solution obtained in Example 1, 24% Chlorantraniliprole (SC, Shandong Weifang Shuangxing Pesticide Co., Ltd.), 15% Indoxacarb (SC, Jingbo Agrochemical Technology Co., Ltd.), 4.5% Lambda-cyhalothrin (EW, Nanjing Huazhou Pharmaceutical Co., Ltd.), 2.5% Deltamethrin (EC, Tianjin Aigefu Pesticide Technology Co., Ltd.), 25% Chlorfluazuron (SC, Hebei Tian Gene Biological Technology Co., Ltd.).

[0076] 3. Test method

[0077] Taking Plutella xylostella as the target, the synergistic effect of the compound pesticide was evaluated by the co-toxic factor method and the co-toxic coefficient method, and the best combination and ratio of the compound pesticide were finally determined.

[0078] (1) Co-toxic factor method to determine the best compound ratio of wood vinegar solution

[0079] Suppose the LC 50 of single agents A and B determined by toxicity test are a and b respectively. The selection of ratio is based on the six equal points of the additive effect line in the isobologram method, which can be represented as a / 5b, a / 2b, a / b, 2a / b, 5a / b. Five kinds of test insecticides are diluted to the lethal concentration using distilled water, and then mixed in the volume ratio of 1:5, 1:2, 1:1, 2:1 and 5:1 to obtain mixed pesticide solutions with different ratios. Each treatment was repeated 3 times, and 15 larvae were taken for each repetition. The calculation formula is as follows:

[0080]

[0081] The mixed agent theoretical mortality in the above formula is the sum of the mortality at the corresponding concentration calculated from the regression equation of each single agent according to the different ratios, while the mixed agent observed mortality is obtained by treating the test insects with the mixed concentration or dose according to the ratio.

[0082] Co-toxic factor ≥ 20 indicates synergistic effect, co-toxic factor ≤ -20 indicates antagonistic effect, and -20 < co-toxic factor < 20 indicates additive effect (Hu et al., 2021). Select the ratio with co-toxic factor greater than 20 to enter the next stage of co-toxic coefficient method test.

[0083] (2) Co-toxic coefficient method to determine the best compound ratio

[0084] Based on the results of the 2.1 co-toxic factor method test, wood vinegar solution was used as the main pesticide, and different ratios were set above and below the synergistic range of the combination of wood vinegar solution and the five pesticides. Indoor toxicity test was carried out with a total effective ingredient mass fraction of 6%. The toxicity regression equation and LC 50 of the compound pesticide at different ratios were calculated, and the co-toxic coefficient (CTC) was obtained by the co-toxic coefficient method proposed by Sun Yunpei. When CTC ≤ 80, it is antagonistic effect, and when 80 <ctc>120 is additive effect, CTC≥120 is synergistic effect.

[0085] Let the compound agent be M, the two agents constituting M be A and B, the toxicity index be TI, and the proportion of A or B in M be P A or P B The calculation method of the co-toxicity coefficient (CTC) is as follows:

[0086]

[0087]

[0088] 4. Results and analysis

[0089] The co-toxicity factor of the compound of the insecticide and the wood vinegar obtained in Example 1 on Plutella xylostella is shown in Table 2.

[0090] Table 2 Co-toxicity factor of the compound of the insecticide and the wood vinegar obtained in Example 1 on Plutella xylostella

[0091]

[0092] Note: Co-toxicity factor≥20, synergistic effect; co-toxicity factor≤-20, antagonistic effect; -20<co-toxicity factor<20, additive effect.

[0093] It can be seen that when the mass ratio of deltamethrin to wood vinegar is 1:55, 1:22, 1:11 and 5:11, the co-toxicity factors are 20.78, 34.69, 82.00 and 26.08 respectively. The co-toxicity factors of these four ratios are all higher than 20, showing synergistic effect, and the co-toxicity factor of the mass ratio of 2:11 is 17.65, which is lower than 20, showing additive effect.

[0094] When the mass ratio of chlorbenzuron to mixed wood vinegar is 1:17, 1:8.5 and 2:8.5, the co-toxicity factors are 56.82, 48.84 and 43.48 respectively, all of which are greater than 20, thus showing synergistic effect, and the co-toxicity factors of other ratios are 11.36 and 8.89, both of which are less than 20, thus showing additive effect.

[0095] When the mass ratio of indoxacarb to mixed wood vinegar is 1:6.5, 2:6.5 and 5:6.5, the co-toxicity factors are 21.81, 25.45 and 26.53 respectively, all of which are greater than 20, thus showing synergistic effect, and the co-toxicity factors of indoxacarb and wood vinegar in other ratios are 1.92 and 10.71 respectively, both of which are less than 20, thus showing additive effect.

[0096] When the mass ratio of imidacloprid and mixed wood vinegar was 1:50, 1:20 and 1:10, the co-toxic factors were 34.78, 40.82 and 29.17 respectively, all greater than 20, showing synergistic effect; the co-toxic factors of the rest ratios were 3.92 and 8.89, both less than 20, showing additive effect.

[0097] When the mass ratio of lambda-cyhalothrin and mixed wood vinegar was 1:37.5, 1:7.5, 2:7.5 and 5:7.5, the co-toxic factors were 26.19, 34.00, 48.98 and 46.80 respectively, all greater than 20, showing synergistic effect; when the ratio was 1:15, the co-toxic factor was 18.37, less than 20, showing additive effect.

[0098] The five insecticides, i.e. deltamethrin, diafenthiuron, indoxacarb, imidacloprid and lambda-cyhalothrin, all showed additive or synergistic effect when mixed with wood vinegar, and no antagonistic effect was observed, so the five insecticides can be mixed with wood vinegar with high feasibility.

[0099] II. Determination of optimal mixing ratio

[0100] 1. Determination of optimal mixing ratio of deltamethrin and wood vinegar

[0101] The screening results of deltamethrin mixed with wood vinegar are shown in Table 3:

[0102] Table 3 Screening of optimal mixing ratio of deltamethrin and wood vinegar by co-toxicity coefficient method

[0103]

[0104]

[0105] The toxicity regression equations of deltamethrin mixed with wood vinegar at the mass ratios of 1:15, 1:10 and 1:5 were Y=2.55X+2.76, Y=2.41X+3.49 and Y=2.58X+3.32 respectively, and the co-toxicity coefficients were 156.30, 201.39 and 123.12 respectively, all higher than 120, among which the CTC value was the largest and the synergistic effect was the strongest at the mass ratio of 1:10, but the synergistic effect was weaker at other ratios. That is, when deltamethrin and wood vinegar were mixed, the synergistic effect of wood vinegar was the strongest at the mass ratio of 1:10, and the co-toxicity coefficient reached 201.39.

[0106] 2. Determination of optimal mixing ratio of diafenthiuron and wood vinegar

[0107] The screening results of diafenthiuron mixed with wood vinegar are shown in Table 4:

[0108] Table 4: Screening of the best ratio of chlorbenzuron and wood vinegar by the method of CTC

[0109]

[0110] It can be seen that when chlorbenzuron and wood vinegar are compounded at a mass ratio of 1:20, 1:15 and 1:10, the CTC values are 143.09, 175.33 and 133.26 respectively, all of which are higher than 120, among which the CTC value is the highest and the synergistic effect is the strongest at a mass ratio of 1:15. However, the synergistic effect is weaker at other ratios. That is, when chlorbenzuron and wood vinegar are mixed, the wood vinegar has a synergistic effect when the mass ratio of chlorbenzuron to wood vinegar is 1:17 (m:m) to 2:8.5 (m:m), and the synergistic effect is the strongest at a mass ratio of 1:15, with a CTC value of 175.33.

[0111] 3. Determination of the best ratio of indoxacarb and wood vinegar

[0112] The screening results of the compound of indoxacarb and wood vinegar are shown in Table 5:

[0113] Table 5: Screening of the best ratio of indoxacarb and wood vinegar by the method of CTC

[0114]

[0115] It can be seen that when indoxacarb and wood vinegar are compounded at a mass ratio of 1:4, 3:7 and 1:1, the CTC values are 133.87, 167.32 and 146.95 respectively, all of which are higher than 120, among which the CTC value is the highest and the synergistic effect is the strongest at a mass ratio of 3:7. However, the synergistic effect is weaker at other ratios. That is, when indoxacarb and wood vinegar are mixed, the wood vinegar has a synergistic effect when the mass ratio of indoxacarb to wood vinegar is 1:6.5 (m:m) to 5:6.5 (m:m), and the synergistic effect is the strongest at a mass ratio of 3:7, with a CTC value of 167.32.

[0116] 4. Determination of the best ratio of imicyafos and wood vinegar

[0117] The screening results of the compound of imicyafos and wood vinegar are shown in Table 6:

[0118] Table 6: Screening of the best ratio of imicyafos and wood vinegar by the method of CTC

[0119]

[0120] It can be seen that the toxicity regression equation of imicyaflofen-methyl and vinegar liquid with mass ratio of 1:26, 1:21 and 1:16 is Y=11.63X-8.83, Y=7.46X-2.11 and Y=3.80X+1.75 respectively, and the CTC is 134.93, 145.99 and 133.46 respectively, all of which are higher than 120, wherein the CTC is the largest when the mass ratio is 1:21, and the synergistic effect is the strongest, but the synergistic effect is weaker when the mass ratio is other. That is, when imicyaflofen-methyl and vinegar liquid are mixed, and the mass ratio of imicyaflofen-methyl to vinegar liquid is 1:50(m:m)-1:10(m:m), the vinegar liquid has a synergistic effect, and the CTC is 145.99 when the mass ratio is 1:21, and the synergistic effect is the strongest.

[0121] 5. Determination of the optimal ratio of lambda-cyhalothrin and vinegar liquid

[0122] The screening results of the mixture of lambda-cyhalothrin and vinegar liquid are shown in Table 7:

[0123] Table 7 CTC screening of the optimal ratio of lambda-cyhalothrin and vinegar liquid

[0124]

[0125] It can be seen that the toxicity regression equation of lambda-cyhalothrin and vinegar liquid with mass ratio of 1:7, 2:7 and 3:7 is Y=5.78X-0.46, Y=2.97X+2.86 and Y=2.99X+2.83 respectively, and the CTC is 132.36, 176.98 and 144.97 respectively, all of which are higher than 120, wherein the CTC is the largest when the mass ratio is 2:7, and the synergistic effect is the strongest, but the synergistic effect is weaker when the mass ratio is other. That is, when lambda-cyhalothrin and vinegar liquid are mixed, and the mass ratio of lambda-cyhalothrin to vinegar liquid is 1:37.5(m:m)-5:7.5(m:m), the vinegar liquid has a synergistic effect, and the CTC is 176.98 when the mass ratio is 2:7, and the synergistic effect is the strongest.

[0126] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical range disclosed by the present application can be easily thought by those skilled in the art, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.< / ctc>

Claims

1. Use of corn-sorghum straw pyroligneous acid in insecticide synergist, characterized in that, the preparation method of the pyroligneous acid comprises the following steps: (1) corn straw and sorghum straw are mixed, crushed and dried, then preheated and pyrolyzed, and then continuously heated to 300-600℃ for solid decomposition to obtain crude pyroligneous acid; (2) the crude pyroligneous acid is stored in a storage tank at low temperature for 6 months, and repeatedly frozen and thawed 3 times during this period, each time for 2 months, then filtered and distilled to retain light components and remove heavy components; (3) the light components are extracted with butyl phosphonate and diethyl ether in sequence, and then the extract is subjected to molecular distillation to evaporate the solvent to obtain the pyroligneous acid; the mass ratio of corn straw to sorghum straw in step (1) is 1:1; the preheating and pyrolysis is heated to a temperature of 150-300℃ at a heating rate of 5℃ / min for 0.5h; the continuous heating rate is 10℃ / min; the solid decomposition time in step (1) is 0.5h; the distillation in step (2) is carried out at 90-105℃ using a molecular distillation device; the insecticide comprises one of deltamethrin, chlorbenzuron, indoxacarb, buprofezin and lambda cyhalothrin; the mass ratio of deltamethrin to pyroligneous acid is 1:(10-15); the mass ratio of chlorbenzuron to pyroligneous acid is 1:(10-20); the mass ratio of indoxacarb to pyroligneous acid is 1:(1-4); the mass ratio of buprofezin to pyroligneous acid is 1:(16-26); the mass ratio of lambda cyhalothrin to pyroligneous acid is (1-3):

7.

2. Use according to claim 1, characterized in that, the filtration is through a 0.22 micron flat membrane.

3. Use according to claim 1, characterized in that, the organic phenol content in the corn-sorghum straw pyroligneous acid is 20-50%.

4. A complex insecticide based on corn-sorghum straw vinegar, characterized by, comprising the following raw materials by weight: deltamethrin 1 part and pyroligneous acid 10 parts; or, indoxacarb 3 parts and pyroligneous acid 7 parts; or, buprofezin 1 part and pyroligneous acid 21 parts; or, lambda cyhalothrin 2 parts and pyroligneous acid 7 parts; or, chlorbenzuron 1 part and pyroligneous acid 15 parts; the preparation method of the pyroligneous acid comprises the following steps: (1) corn straw and sorghum straw are mixed, crushed and dried, then preheated and pyrolyzed, and then continuously heated to 300-600℃ for solid decomposition to obtain crude pyroligneous acid; (2) the crude pyroligneous acid is stored in a storage tank at low temperature for 6 months, and repeatedly frozen and thawed 3 times during this period, each time for 2 months, then filtered and distilled to retain light components and remove heavy components; (3) the light components are extracted with butyl phosphonate and diethyl ether in sequence, and then the extract is subjected to molecular distillation to evaporate the solvent to obtain the pyroligneous acid; the mass ratio of corn straw to sorghum straw in step (1) is 1:1; the preheating and pyrolysis is heated to a temperature of 150-300℃ at a heating rate of 5℃ / min for 0.5h; the continuous heating rate is 10℃ / min; the solid decomposition time in step (1) is 0.5h; the distillation in step (2) is carried out at 90-105℃ using a molecular distillation device.

Images