Sulfonate surfactant for improving adhesion of pesticide and application thereof

Abstract

The application discloses sulfonate surfactant for improving pesticide adhesion and application thereof, and belongs to the technical field of surfactants. Modified sodium lignosulfonate is obtained by esterification of sodium lignosulfonate with benzoic anhydride. The esterification reaction reduces the hydrophilicity of the sodium lignosulfonate and improves the hydrophobicity. Then, the surface of the sodium lignosulfonate is coated with titanium dioxide through hydrophobic self-assembly and hydrothermal treatment, so that a porous and rough structure is obtained. The rough structure can improve the anchoring capacity on the leaf surface, and the porous structure can disperse the shear force of rainwater washing and avoid the rainwater washing from falling off the leaf surface. The sulfonic acid group can increase photo-generated carriers, improve the separation efficiency of photo-generated electrons and holes, improve the absorption rate of titanium dioxide to ultraviolet light, and effectively adsorb and combine water molecules due to the strong polarity of the sulfonic acid group, so that in-situ hydrolysis of tetrabutyl titanate on the surface of the porous sodium lignosulfonate nanosphere is promoted, and a titanium dioxide coating layer is formed through condensation.

Description

Technical Field

[0001] This invention belongs to the field of surfactant technology, specifically a sulfonate surfactant for improving pesticide adhesion and its application. Background Technology

[0002] Pesticides, as a key means of ensuring crop yields and reducing food losses, can effectively prevent significant yield reductions caused by pests, diseases, and weeds. However, in practical applications, traditional pesticide formulations have obvious shortcomings: the pesticide particles in these formulations are relatively large, making them prone to drifting and rolling during application, directly leading to low pesticide utilization efficiency. To achieve the expected control goals, large amounts and repeated applications are often required, ultimately increasing agricultural costs and posing a serious threat to the ecological environment and human health.

[0003] Surfactants are a class of surface-active compounds that are soluble in liquids and can be directionally adsorbed at liquid-gas and liquid-solid interfaces, even at low concentrations, significantly reducing the surface tension or interfacial tension of the system. In the pesticide industry, these surfactants are indispensable, primarily performing key functions such as wetting, dispersing, emulsifying, and defoaming. They are hailed as the "industrial MSG" of the pesticide industry, not only as a core component of pesticide formulation processing but also as enabling the active ingredients of pesticides to fully exert their efficacy in controlling pests, diseases, and weeds. This improves pesticide effectiveness, reduces pesticide dosage, and thus mitigates the potential environmental impact of pesticides.

[0004] Among various pesticide surfactants, sulfonate surfactants have unique advantages due to their structural characteristics: the sulfonic acid groups in their molecules are highly hydrophilic, can remain stable in acidic or alkaline media, and are easy to compound with other types of surfactants to further enhance the dispersion effect of pesticide formulations. Therefore, they are widely used in pesticide adjuvant systems.

[0005] To address the aforementioned issues, lignin and its modified derivatives have gradually gained widespread application in the pesticide field due to their advantages such as low cost, easy availability, good biocompatibility, and biodegradability, with sodium lignin sulfonate being the most common. However, sodium lignin sulfonate has a significant drawback: its excessive water solubility causes pesticide formulations prepared with it to be easily washed away by rainwater after application to crop leaves, making it difficult to form a stable adhesion and ultimately affecting the sustained control effect of pesticides. Summary of the Invention

[0006] The purpose of this invention is to provide a sulfonate surfactant that enhances pesticide adhesion and its application. Modified sodium lignin sulfonate is obtained by esterification of sodium lignin sulfonate with benzoic anhydride. The esterification reaction reduces the hydrophilicity and increases the hydrophobicity of sodium lignin sulfonate. After crosslinking in reverse phase suspension, a porous sodium lignin sulfonate nanosphere structure is formed. Then, titanium dioxide is coated on the surface by solvothermal treatment to obtain a porous and rough structure. The rough structure can improve the ability to anchor on the leaf surface, and the porous structure can disperse the shear force of rainwater erosion, preventing it from being washed off the leaf surface by rainwater.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A sulfonate surfactant for improving pesticide adhesion is prepared by the following steps:

[0009] Step 1: Using sodium lignosulfonate as raw material, benzoic anhydride is used as a lipophilic group to esterify sodium lignosulfonate to obtain modified sodium lignosulfonate.

[0010] Step 2: Using modified sodium lignosulfonate as raw material, epichlorohydrin as crosslinking agent, and polyetheramine-230 as chain extender, porous sodium lignosulfonate nanospheres were prepared by reverse suspension crosslinking.

[0011] Step 3: Titanium dioxide nanoparticles are loaded onto the surface of porous sodium lignosulfonate nanospheres through solvothermal treatment to obtain photodegradation resistant sodium lignosulfonate nanospheres; the photodegradation resistant sodium lignosulfonate nanospheres, sodium styrene sulfonate, and alkylbenzene sulfonate are stirred and mixed in a mass ratio of 1:8:9 to obtain a sulfonate surfactant that improves pesticide adhesion.

[0012] This invention also provides the application of a sulfonate surfactant that enhances pesticide adhesion in pesticide suspensions.

[0013] Furthermore, the specific preparation steps of modified sodium lignosulfonate are as follows:

[0014] Lithium chloride and N,N-dimethylformamide were stirred and mixed to obtain an active solution with a mass fraction of 10-12%. Sodium lignosulfonate and the active solution were added to a reaction vessel and stirred for 30-40 min under a nitrogen atmosphere, at 90-95℃ and 500-600 r / min. The mixture was then cooled to room temperature, and benzoic anhydride and triethylamine were added. The mixture was then heated to 60-70℃ and stirred for 24-26 h. The mixture was centrifuged at 8000-9000 r / min for 5-6 min, filtered, and the supernatant was retained. Isopropanol was added to the supernatant, and the mixture was centrifuged at 8000-9000 r / min for 5-6 min. The mixture was filtered, and the filter cake was washed 2-4 times with deionized water and anhydrous ethanol, respectively. The cake was then vacuum dried at 60-70℃ for 1-2 h to obtain modified sodium lignosulfonate.

[0015] Furthermore, the ratio of sodium lignosulfonate, active liquid, benzoic anhydride, triethylamine and isopropanol is 20-30g: 300-350mL: 80-90g: 10-12g: 6-7L.

[0016] Furthermore, the specific preparation steps of porous sodium lignosulfonate nanospheres are as follows:

[0017] Modified sodium lignosulfonate and a 1 mol / L NaOH solution were stirred to obtain a mixed solution. The mixed solution, polyetheramine-230, epichlorohydrin, and anhydrous ethanol were added to a reaction vessel and stirred for 30-40 min at 20-25℃ and 500-600 r / min. Then, Span 60 and liquid paraffin were added, and stirring was continued for 20-30 min. The mixture was heated to 90-95℃, and a 50-60% NaOH solution was added. The reaction was continued for 2-3 h, and the mixture was allowed to stand and separate into layers. The upper oil phase was removed, and the organic phase was washed 2-3 times with petroleum ether and deionized water, respectively. The mixture was then freeze-dried at -10℃ for 48-50 h to obtain porous sodium lignosulfonate nanospheres.

[0018] Furthermore, the ratio of modified sodium lignosulfonate to NaOH solution is 18-20g: 20-25g.

[0019] Furthermore, the ratio of the mixed solution, polyetheramine-230, epichlorohydrin, anhydrous ethanol, Span 60, liquid paraffin, and NaOH solution is 30-40g: 2-4g: 80-90mL: 10-12mL: 1-2g: 90-100g: 1-2mL.

[0020] Furthermore, the specific preparation steps of sulfonate surfactants are as follows:

[0021] Porous sodium lignosulfonate nanospheres, deionized water, tetrabutyl titanate, and anhydrous ethanol were added to a polytetrafluoroethylene-lined hydrothermal reactor. The mixture was stirred for 30-40 minutes at 20-25°C and 500-600 rpm, then heated to 160-170°C and stirred for another 3-4 hours. After natural cooling to room temperature, the product was washed 2-4 times with deionized water and anhydrous ethanol, and then freeze-dried at -40°C for 1-2 hours to obtain a sulfonate surfactant that enhances pesticide adhesion.

[0022] Furthermore, the ratio of porous sodium lignosulfonate nanospheres, deionized water, tetrabutyl titanate, and anhydrous ethanol is 50-60g: 1-2L: 20-30mL: 3-4L.

[0023] The beneficial effects of this invention are:

[0024] 1. The sulfonate surfactant prepared in this invention is obtained by compounding anti-photodegradation sodium lignin sulfonate nanospheres, sodium styrene sulfonate, and alkylbenzene sulfonate as raw materials. The anti-photodegradation sodium lignin sulfonate nanospheres of this invention are modified sodium lignin sulfonate by esterification of sodium lignin sulfonate with benzoic anhydride. The esterification reaction reduces the hydrophilicity of sodium lignin sulfonate and increases its hydrophobicity. After crosslinking with reverse phase suspension, a porous sodium lignin sulfonate nanosphere structure is formed. Then, titanium dioxide is coated on the surface by solvothermal treatment to obtain a porous and rough structure. The rough structure can improve the anchoring ability on the leaf surface, and the porous structure can disperse the shear force of rainwater scouring, preventing it from being washed off by rainwater.

[0025] 2. The sulfonate surfactant of the present invention contains titanium dioxide. Most pesticides are sensitive to ultraviolet light and are prone to photo-oxidative decomposition when exposed to sunlight, which leads to a rapid decline in efficacy. Titanium dioxide can absorb ultraviolet light, reduce the direct exposure of pesticide molecules to ultraviolet light, and avoid photo-oxidative decomposition.

[0026] 3. The sulfonic acid group in the sulfonate surfactant of the present invention can combine with titanium ions on the surface of titanium dioxide through electrostatic interaction, inhibit the recombination of photogenerated electron-hole pairs, thereby improving the separation efficiency of photogenerated carriers and further enhancing the absorption capacity of titanium dioxide for ultraviolet light. In the process of titanium dioxide preparation, the strong polarity of the sulfonic acid group can effectively adsorb and bind water molecules, thereby promoting the in-situ hydrolysis of tetrabutyl titanate on the surface of lignin nanospheres to generate titanium hydroxide, which further condenses to form a titanium dioxide coating layer.

[0027] 4. The photodegradable sodium lignosulfonate nanospheres of the present invention, after being modified by hydrophobic benzoic anhydride, can be uniformly distributed on the leaf surface. The rough and porous spherical structure forms a topological structure with the wax layer of the leaf, which allows it to be firmly embedded in the gaps between the waxy structures on the leaf surface, thereby having good anti-erosion ability, reducing the amount of surfactant added, avoiding the damage to the wax layer structure on the leaf surface caused by the addition of a large amount of surfactant, and increasing the retention on the leaf surface.

[0028] 5. In this invention, atrazine technical grade, sulfonate surfactant, wetting agent SR-02, and kaolin are ground and homogenized to obtain a pesticide product. Because the sodium lignin sulfonate nanospheres containing anti-photodegradation surfactant have a special rough and porous surface structure, they are conducive to full contact with atrazine technical grade during grinding, resulting in a large amount of active ingredients adhering to the plant surface and a high utilization rate of active ingredients, thereby reducing the loss of effective ingredients due to uneven dispersion. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1: A sulfonate surfactant for improving pesticide adhesion, prepared by the following steps:

[0031] S1: Lithium chloride and N,N-dimethylformamide were mixed to obtain an active solution with a mass fraction of 12%. 30g of sodium lignosulfonate and 350mL of the active solution were added to a reaction vessel and stirred for 40min at 95℃ and 600r / min under a nitrogen atmosphere. The mixture was then cooled to room temperature, and 90g of benzoic anhydride and 12g of triethylamine were added. The mixture was then heated to 70℃ and stirred for 26h. The mixture was centrifuged at 9000r / min for 6min, filtered, and the supernatant was retained. 7L of isopropanol was added to the supernatant, and the mixture was centrifuged at 9000r / min for 6min. The mixture was filtered, and the filter cake was washed 4 times with deionized water and 4 times with anhydrous ethanol. The mixture was then vacuum dried at 70℃ for 2h to obtain modified sodium lignosulfonate.

[0032] S2: 20g of modified sodium lignosulfonate and 25g of 1mol / L NaOH solution were stirred and mixed to obtain a mixed solution; 40g of the mixed solution, 4g of polyetheramine-230, 90mL of epichlorohydrin and 12mL of anhydrous ethanol were added to the reaction vessel and stirred for 40min at 25℃ and 600r / min. Then, 2g of Span 60 and 100g of liquid paraffin were added and stirred for another 30min. The mixture was heated to 95℃ and then 2mL of 60% NaOH solution was added. The reaction was continued for 3h. The mixture was allowed to stand and separate into layers. The upper oil phase was removed and the organic phase was washed three times with petroleum ether and deionized water, respectively. The mixture was then freeze-dried at -10℃ for 50h to obtain porous sodium lignosulfonate nanospheres.

[0033] S3: 60g of porous sodium lignosulfonate nanospheres, 2L of deionized water, 30mL of tetrabutyl titanate and 4L of anhydrous ethanol were added to a polytetrafluoroethylene-lined hydrothermal reactor. The mixture was stirred at 25℃ and 600r / min for 40min, then heated to 170℃ and stirred for 4h. After natural cooling to room temperature, the product was washed four times with deionized water and anhydrous ethanol, and then freeze-dried at -40℃ for 2h to obtain photodegradable sodium lignosulfonate nanospheres. The photodegradable sodium lignosulfonate nanospheres, sodium styrene sulfonate and alkylbenzene sulfonate were mixed at a mass ratio of 1:8:9 to obtain a sulfonate surfactant that improves pesticide adhesion.

[0034] Example 2: The present invention provides a sulfonate surfactant to improve pesticide adhesion. The difference from Example 1 is that the ratio of sodium lignosulfonate, active liquid, benzoic anhydride, triethylamine and isopropanol in step S1 is 25g:330mL:85g:11g:6L.

[0035] Example 3: The present invention provides a sulfonate surfactant to improve pesticide adhesion. The difference from Example 1 is that the ratio of the mixed solution, polyetheramine-230, epichlorohydrin, anhydrous ethanol, Span 60, liquid paraffin and NaOH solution in step S2 is 38g:3g:88mL:11mL:1g:98g:1mL.

[0036] Example 4: The present invention provides a sulfonate surfactant to improve pesticide adhesion. The difference from Example 1 is that the ratio of porous sodium lignin sulfonate nanospheres, deionized water, tetrabutyl titanate and anhydrous ethanol in step S3 is 50g:1L:20mL:3L.

[0037] Comparative Example 1: Based on Example 1, the modified sodium lignin sulfonate in step S2 was replaced with the raw material sodium lignin sulfonate in step S1, while the other steps remained unchanged, to prepare a sulfonate surfactant that improves pesticide adhesion.

[0038] Comparative Example 2: Based on Example 1, the porous sodium lignin sulfonate nanospheres in step S3 were replaced with the modified sodium lignin sulfonate prepared in step S1, while the other steps remained unchanged, to prepare a sulfonate surfactant that improves pesticide adhesion.

[0039] Comparative Example 3: Based on Example 1, without the treatment in step S3, the porous sodium lignosulfonate nanospheres prepared in step S2 were directly used as sulfonate surfactants to improve pesticide adhesion.

[0040] The performance of the sulfonate surfactants obtained in Examples 1-4 and Comparative Examples 1-3 was tested. 81.6g of 97% atrazine technical grade, 4g of sulfonate surfactant, 2g of wetting agent SR-02, and 12.4g of kaolin were mixed evenly and ground to obtain a mixed slurry. The mixed slurry was added to a high-pressure homogenizer and homogenized under the conditions of pressure of 500Mpa, flow rate of 30L / min, temperature of 30℃, and rotation speed of 3000 rpm to obtain the pesticide product.

[0041] 1. Pesticide residue test: Select corn leaves, dry them at 60℃ to constant weight, disperse 2g of pesticide product in 98mL of deionized water, spray 5mL of pesticide product onto the corn leaves, let stand for 30min, weigh the corn leaves and record the initial weight, use a rainfall simulator (rainfall intensity 50mm / h, duration 30min) to wash the corn leaves, quickly absorb the surface moisture after washing, dry at 60℃ and weigh the corn leaves again, record the weight after washing, pesticide residue rate (%) = weight after washing / initial weight, calculate the pesticide residue rate.

[0042] 2. Leaf contact angle test: The contact angle of the pesticide product on the corn leaf is measured using an optical contact angle meter.

[0043] 2g of pesticide product was dispersed in 98mL of deionized water. Corn leaves of the same thickness and size were then fixed on a glass slide for the experiment. At room temperature, 5mL of pesticide product was sprayed onto the corn leaves. After the droplets stabilized, the contact angle value was recorded. Each sample was measured at least 5 times at different positions, and the average value was taken.

[0044] 3. Suspension rate test: The suspension rate of liquid pesticide products was determined using the CIPAC MT15 standard method. 1.0 g of pesticide product was accurately weighed into a 250 mL Erlenmeyer flask, and 50 mL of prepared hard water was added. The suspension was shaken 240 times within 120 seconds, and then placed in a 30°C water bath for 15 minutes. After standing, the suspension was transferred to a 250 mL standard graduated cylinder, and 30°C hard water was added to bring the volume to a final volume. The flask was then capped and shaken up and down 30 times at a frequency of once every 2 seconds. The flask was then placed in a 30°C water bath for 30 minutes. Finally, the top 9 / 10 (225 mL) of the suspension was quickly removed using a vacuum pump for measurement.

[0045] 4. Decomposition rate test: Disperse 1g of pesticide product into a 100mL volumetric flask, take out 400μL of the diluted solution and spread it in a 4cm diameter glass petri dish, protect it from light and dry it to form a film, and irradiate it under 30W, 310nm ultraviolet light for 0h, 24h and 48h respectively. Then dissolve the sample with 10mL of methanol and use HPLC to detect the original pesticide product content. The effective ingredient (%) of pesticide product = the effective integral area of ​​pesticide product component in HPLC / (13088X100)×100%, and the decomposition rate (%) = (1 - effective ingredient of pesticide product in 24h / effective ingredient of pesticide product in 0h)×100%.

[0046] The results are shown in Table 1:

[0047] Table 1 Performance Test Table for Pesticide Products

[0048] project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Pesticide residue rate (%) 83.2 82.6 82.3 82.1 82.2 52.3 70.5 63.8 Contact angle (°) 59.1 61.4 61.6 61.2 61.3 42.5 73.8 68.2 Suspension rate (%) 99.5 96.8 96.5 96.1 96.5 82.1 89.3 92.5 Decomposition rate (%) 4.3 4.5 4.4 4.5 4.6 5.8 5.7 11.5

[0049] As can be seen from Table 1, the pesticide residue rate, leaf contact angle and suspension rate of the sulfonate surfactants obtained in Examples 1-4 are significantly better than those of the comparative examples. This indicates that when the sulfonate surfactants prepared in this invention are used as pesticide dispersants, they can maintain the uniform dispersion of pesticide active ingredients, prevent sedimentation and agglomeration, and have sufficient hydrophobicity and resistance to photodegradation, making them less susceptible to being washed away by rainwater.

[0050] Comparative Example 1 replaced the modified sodium lignosulfonate with the raw sodium lignosulfonate. The esterification reaction between benzoic anhydride and sodium lignosulfonate was missing, and hydrophobic segments were not introduced. This disrupted the hydrophilic-hydrophobic balance of the sodium lignosulfonate. The raw sodium lignosulfonate is extremely hydrophilic; even when nanospheres are formed, their surface remains predominantly hydrophilic. When the pesticide solution is applied to the leaf surface, rainwater easily combines with the hydrophilic surface, washing away the surfactant and adsorbed pesticide particles, preventing stable adhesion and thus reducing pesticide residue. The esterification reaction not only reduces hydrophilicity but also increases the steric hindrance effect on pesticide particles through hydrophobic segments. Unesterified sodium lignosulfonate has weak adsorption capacity for pesticide particles, easily causing particle aggregation and leading to an unstable suspension system. Excessive hydrophilicity causes the pesticide solution to spread rapidly on the leaf surface, with a contact angle far lower than in the example. Over-spreading leads to localized dilution of the pesticide concentration, and even flow along the leaf surface into the soil, reducing the effective pesticide amount on the crop surface and affecting the insecticidal and fungicidal effects.

[0051] Comparative Example 2 replaced the porous sodium lignosulfonate nanospheres with modified sodium lignosulfonate. Lacking reverse-phase suspension cross-linking, a porous structure was not formed, thus failing to utilize the shear force dispersion and anchoring enhancement effects of the porous structure. The lack of microscopic anchoring points in the porous structure resulted in poor spreadability of the pesticide solution on the leaf surface. The larger contact angle made the pesticide solution prone to forming small droplets, failing to uniformly cover the leaf surface and hindering the enhancement of anchoring effect through surface roughening. The high specific surface area of ​​the porous structure provides more sites for the hydrolysis of tetrabutyl titanate. Insufficient titanium dioxide leads to a decrease in ultraviolet light absorption capacity, failing to effectively inhibit the photo-oxidative decomposition of pesticides and reducing the duration of efficacy.

[0052] Comparative Example 3 directly used the porous sodium lignosulfonate nanospheres prepared in step S3 as a sulfonate surfactant to enhance pesticide adhesion. Lacking tetrabutyl titanate hydrolysis loading, it did not form a titanium dioxide coating layer, thus failing to utilize the ultraviolet light absorption and surface roughening effects of titanium dioxide. While titanium dioxide loading creates a rough surface, enhancing mechanical anchoring with the leaf wax layer, the porous nanospheres lacked a titanium dioxide roughening layer. The anchoring effect of the porous structure was limited, making them prone to detachment during rainwater washing, leading to decreased pesticide residue. Furthermore, they could not block direct ultraviolet light from irradiating pesticide molecules. In open-air environments, the photolysis rate of pesticides accelerated, shortening the duration of efficacy. The lack of a titanium dioxide layer and the high smoothness of the porous surface resulted in a larger contact angle, reducing the uniformity of pesticide spread and affecting efficacy.

[0053] Chlorfenapyr·fluoxetine is a highly effective, broad-spectrum insecticide composed of two insecticides with different mechanisms of action. Chlorfenapyr's mechanism of action is mainly through stomach poison and contact action, with some systemic activity. It mainly acts on the mitochondria of pests, inhibiting their respiration and hindering the synthesis of intracellular energy (ATP). Fluoxetine's mechanism of action is through systemic, contact, and osmotic action, with a unique "anti-feeding" effect. It acts on the pest's nervous system, activating a special "ryanodine receptor," leading to continuous muscle contraction and paralysis. Applying the sulfonate surfactant prepared in this application to the suspension prepared from chlorfenapyr and flonicamid can result in a large amount of active ingredients adhering to the plant surface, high utilization rate of active ingredients, and thus reduce the loss of effective ingredients due to uneven dispersion.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A sulfonate surfactant for improving pesticide adhesion, characterized in that, Prepared by the following steps: Step 1: Using sodium lignosulfonate as raw material, benzoic anhydride is used as a lipophilic group to esterify sodium lignosulfonate to obtain modified sodium lignosulfonate. Step 2: Using modified sodium lignosulfonate as raw material, epichlorohydrin as crosslinking agent, and polyetheramine-230 as chain extender, porous sodium lignosulfonate nanospheres were prepared by reverse suspension crosslinking. Step 3: Titanium dioxide nanoparticles are loaded onto the surface of porous sodium lignosulfonate nanospheres via hydrothermal synthesis to obtain photodegradable sodium lignosulfonate nanospheres; the photodegradable sodium lignosulfonate nanospheres, sodium styrene sulfonate, and alkylbenzene sulfonate are mixed in a mass ratio of 1:8:9 to obtain a sulfonate surfactant that enhances pesticide adhesion. The specific preparation steps for the modified sodium lignin sulfonate are as follows: Sodium lignosulfonate and active liquid were added to a reaction vessel and stirred for 30-40 min under a nitrogen atmosphere, at 90-95℃ and 500-600 r / min. The mixture was then cooled to room temperature, and benzoic anhydride and triethylamine were added. The mixture was then heated to 60-70℃ and stirred for 24-26 h. The mixture was centrifuged at 8000-9000 r / min for 5-6 min, filtered, and the supernatant was retained. Isopropanol was added to the supernatant, and the mixture was centrifuged at 8000-9000 r / min for 5-6 min. The mixture was then filtered, and the filter cake was washed 2-4 times with deionized water and anhydrous ethanol, respectively. The mixture was then vacuum dried at 60-70℃ for 1-2 h to obtain modified sodium lignosulfonate. The ratio of sodium lignosulfonate, active liquid, benzoic anhydride, triethylamine and isopropanol is 20-30g: 300-350mL: 80-90g: 10-12g: 6-7L; The specific preparation steps of the active liquid are as follows: Lithium chloride and N,N-dimethylformamide were stirred and mixed to obtain an active solution with a mass fraction of 10-12%. The specific preparation steps of the photodegradable sodium lignosulfonate nanospheres are as follows: Porous sodium lignosulfonate nanospheres, deionized water, tetrabutyl titanate, and anhydrous ethanol were added to a polytetrafluoroethylene-lined hydrothermal reactor. The mixture was stirred for 30-40 minutes at 20-25°C and 500-600 r / min, then heated to 160-170°C and stirred for another 3-4 hours. The mixture was then allowed to cool naturally to room temperature. The product was washed 2-4 times with deionized water and anhydrous ethanol, respectively, and then freeze-dried at -40°C for 1-2 hours to obtain photodegradable sodium lignosulfonate nanospheres.

2. The sulfonate surfactant for improving pesticide adhesion according to claim 1, characterized in that, The specific preparation steps of the porous sodium lignosulfonate nanospheres are as follows: The modified sodium lignosulfonate and a 1 mol / L NaOH solution were stirred to obtain a mixed solution. The mixed solution, polyetheramine-230, epichlorohydrin, and anhydrous ethanol were added to a reaction vessel and stirred for 30-40 min at 20-25℃ and 500-600 r / min. Then, Span 60 and liquid paraffin were added, and stirring was continued for 20-30 min. The mixture was heated to 90-95℃, and a 50-60% NaOH solution was added. The reaction was continued for 2-3 h, and the mixture was allowed to stand and separate into layers. The upper oil phase was removed, and the organic phase was washed 2-3 times with petroleum ether and deionized water, respectively. The mixture was then freeze-dried at -10℃ for 48-50 h to obtain porous sodium lignosulfonate nanospheres.

3. The sulfonate surfactant for improving pesticide adhesion according to claim 2, characterized in that, The ratio of modified sodium lignosulfonate to NaOH solution is 18-20g: 20-25g.

4. A sulfonate surfactant for improving pesticide adhesion according to claim 2, characterized in that, The ratio of the mixed solution, polyetheramine-230, epichlorohydrin, anhydrous ethanol, Span 60, liquid paraffin, and NaOH solution is 30-40g: 2-4g: 80-90mL: 10-12mL: 1-2g: 90-100g: 1-2mL.

5. The application of the sulfonate surfactant for improving pesticide adhesion as described in claim 1 in pesticide suspensions.