A method for preparing a lignin sulfonate sodium dispersant composition for pesticides

Abstract

The application discloses a preparation method of a pesticide lignosulfonate sodium dispersant composition and belongs to the technical field of dispersants. The method comprises the following steps: S1, taking papermaking black liquor as raw material, performing standing precipitation, flocculation precipitation, membrane concentration and acid precipitation treatment to obtain purified lignin; S2, adding the purified lignin into water, adjusting the pH of the system to 10-11, then adding hydrogen peroxide to perform pre-oxidation, then adding formaldehyde and sodium sulfite to perform sulfomethylation reaction, and adding formaldehyde to perform polycondensation reaction; cooling and discharging, and performing spray drying to obtain lignosulfonate sodium; and S3, adding the lignosulfonate sodium and 1-ethyl-3-methyl imidazolium L-lactate into water and stirring and uniformly mixing, adding stevioside to perform ultrasonic treatment, forming a homogeneous system, and performing spray drying to obtain the pesticide lignosulfonate sodium dispersant composition. The lignosulfonate sodium dispersant composition can effectively improve the pesticide dispersion stability and pesticide biological activity, and meets the pesticide use requirement.

Description

Technical Field

[0001] This invention relates to the field of dispersant technology, and more specifically, to a method for preparing a sodium lignosulfonate dispersant composition for pesticides. Background Technology

[0002] In pesticide formulations, dispersants play a crucial role, directly affecting the dispersion stability, suspension properties, and bioavailability of the active ingredients. Lignosulfonates, as green surfactants derived from renewable resources, have the potential to replace petroleum-based dispersants in pesticide formulations. However, existing sodium lignosulfonate dispersants still have shortcomings, failing to meet the requirements of pesticide formulations in terms of dispersion stability and bioactivity. Therefore, the development of new dispersants is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a sodium lignosulfonate dispersant composition for pesticides.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for preparing a sodium lignosulfonate dispersant composition for pesticides includes the following steps:

[0006] S1. Using papermaking black liquor as raw material, purified lignin is obtained through static sedimentation, flocculation sedimentation, membrane concentration, and acid precipitation.

[0007] S2. Add purified lignin to water, adjust the pH of the system to 10-11 with sodium hydroxide, add hydrogen peroxide for pre-oxidation, then add formaldehyde and sodium sulfite for sulfonation reaction, followed by formaldehyde condensation reaction; after the reaction is completed, cool and discharge the material, spray dry to obtain sodium lignin sulfonate.

[0008] S3. Sodium lignosulfonate and 1-ethyl-3-methylimidazolium L-lactate are added to water and stirred until homogeneous. Stevioside is added and ultrasonically treated to form a homogeneous system. The mixture is then spray-dried to obtain a pesticide-grade sodium lignosulfonate dispersant composition.

[0009] The present invention is further configured such that, in step S1, membrane concentration is to treat the filtrate after flocculation and sedimentation with membrane concentration and retain crude lignin with a relative molecular weight of 5000-10000 to obtain a concentrated liquid with a solid content of 25-30%.

[0010] The present invention is further configured such that, in step S1, sulfuric acid is used for acid precipitation at 50-60°C.

[0011] The present invention is further configured such that, in step S2, during the sulfonation reaction, formaldehyde and sodium sulfite are added in a mass ratio of purified lignin to formaldehyde and sodium sulfite of 1:(0.4-1):(0.1-0.3).

[0012] The present invention is further configured such that, in step S2, the sulfonylation reaction temperature is 85-95℃ and the reaction time is 4-8h.

[0013] The present invention is further configured such that, in step S2, during the polycondensation reaction, formaldehyde is added at a mass ratio of purified lignin to formaldehyde of 1:0.1-0.2.

[0014] The present invention is further configured such that, in step S2, the polycondensation reaction temperature is 90-100℃ and the polycondensation reaction time is 2-3h.

[0015] The present invention is further configured such that the sodium lignosulfonate dispersant composition is made from the following raw materials in parts by weight: 90-95 parts sodium lignosulfonate, 18-22 parts 1-ethyl-3-methylimidazolium L-lactate, and 7-13 parts steviol glycosides.

[0016] In summary, the present invention has the following beneficial effects:

[0017] This invention uses papermaking black liquor as raw material and combines a staged sulfonation-condensation reaction to control the molecular weight distribution and degree of sulfonation to prepare sodium lignin sulfonate. Furthermore, 1-ethyl-3-methylimidazolium L-lactate and steviol glycosides are introduced to construct a multi-component stable system, resulting in a sodium lignin sulfonate dispersant composition that effectively improves pesticide dispersion stability and pesticide bioactivity, thus meeting the needs of pesticide use. Detailed Implementation

[0018] The technical solution 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.

[0019] The pesticide-grade sodium lignosulfonate dispersant composition of the present invention is prepared by the following method:

[0020] S1. After allowing the black liquor from papermaking to settle at room temperature for 24 hours, filter it. Add polyacrylamide flocculant to the filtrate for flocculation and sedimentation, and filter it again. The resulting filtrate is concentrated by membrane treatment to retain crude lignin with a relative molecular weight of 5000-10000, resulting in a concentrate with a solid content of 25-30%. Add 15wt% sulfuric acid to the concentrate and acid precipitate the crude lignin at 50-60℃ (the pH of the system during acid precipitation is 3). After pressure filtration, purified lignin is obtained.

[0021] S2. Add purified lignin to water to form a system with a lignin content of 45-50 wt%. Then, adjust the pH of the system to 10-11 with 10 wt% sodium hydroxide. Add 3 wt% hydrogen peroxide and pre-oxidize at 50℃ for 1 h. Add formaldehyde and sodium sulfite (added in a mass ratio of purified lignin to formaldehyde and sodium sulfite of 1:(0.4-1):(0.1-0.3)) and carry out a sulfonation reaction at 85-95℃ for 4-8 h. After the reaction, add formaldehyde (the mass ratio of added formaldehyde to purified lignin is 1:0.1-0.2) and carry out a condensation reaction at 90-100℃ for 2-3 h. After the reaction is completed, cool and discharge the material, spray dry, and obtain sodium lignin sulfonate.

[0022] S3. At 50℃, sodium lignosulfonate and 1-ethyl-3-methylimidazolium L-lactate are added to water and stirred until homogeneous. Stevioside is then added and the mixture is ultrasonically treated to form a homogeneous system. The mixture is then spray-dried to obtain a pesticide-grade sodium lignosulfonate dispersant composition. This composition is made from the following parts by weight of raw materials: 90-95 parts by weight of sodium lignosulfonate, 18-22 parts by weight of 1-ethyl-3-methylimidazolium L-lactate, and 7-13 parts by weight of steviolside.

[0023] Example 1

[0024] S1. After allowing the black liquor from papermaking to settle at room temperature for 24 hours, filter it. Add polyacrylamide flocculant to the filtrate for flocculation and sedimentation, and filter it again. The resulting filtrate is concentrated by membrane treatment to retain crude lignin with a relative molecular weight of 5000-10000, resulting in a concentrate with a solid content of 27.8%. Add 15wt% sulfuric acid to the concentrate and acid precipitate the crude lignin at 50℃ (the pH of the system during acid precipitation is 3). After pressure filtration, purified lignin is obtained.

[0025] S2. Purified lignin was added to water to form a system with a lignin content of 45 wt%. Then, the pH of the system was adjusted to 10.5 with 10 wt% sodium hydroxide. 3 wt% hydrogen peroxide was added and pre-oxidized at 50°C for 1 h. Formaldehyde and sodium sulfite (added in a mass ratio of purified lignin to formaldehyde and sodium sulfite of 1:0.5:0.13) were added and sulfonation reaction was carried out at 90°C for 6 h. After the reaction, formaldehyde (the mass ratio of added formaldehyde to purified lignin was 1:0.2) was added and polycondensation reaction was carried out at 100°C for 2.5 h. After the reaction was completed, the material was cooled, discharged, and spray-dried to obtain sodium lignin sulfonate.

[0026] S3. Prepare the following raw materials by weight: 90 parts by weight of sodium lignosulfonate, 19.5 parts by weight of 1-ethyl-3-methylimidazolium L-lactate, and 8.3 parts by weight of steviol glycosides; at 50°C, add sodium lignosulfonate and 1-ethyl-3-methylimidazolium L-lactate to 200 parts by weight of water and stir to mix evenly. Add steviol glycosides and sonicate to form a homogeneous system. Spray dry to obtain a pesticide sodium lignosulfonate dispersant composition.

[0027] Comparative Example 1

[0028] A sodium lignosulfonate dispersant composition was prepared according to Example 1, but 1-ethyl-3-methylimidazolium L-lactate was not added in step S3.

[0029] Comparative Example 2

[0030] A sodium lignosulfonate dispersant composition was prepared according to Example 1, but stevioside was not added in step S3.

[0031] Comparative Example 3

[0032] Sodium lignosulfonate was prepared according to Example 1.

[0033] The sodium lignosulfonate dispersant compositions prepared in Example 1, Comparative Examples 1-2, and Comparative Example 3, and the sodium lignosulfonate in Comparative Example 3 were used as dispersants a, b, c, and d, respectively. Dispersants a-d were mixed with dimethomorph technical, organobentonite, and water, respectively, and then ground and dispersed to prepare suspensions a-d containing 40 wt% dimethomorph technical and 3.5 wt% sodium lignosulfonate. The suspension rates of each suspension were tested according to GB / T14825-2006 (Determination of Suspension Rate of Pesticides), and the thermal storage stability was tested according to GB / T19136-2003 (Determination of Thermal Storage Stability of Pesticides). The results are shown in Table 1. The bioactivity was tested according to the method described in "Bioactivity Example 1: Field Efficacy Trial for Controlling Cucumber Downy Mildew" in the patent "A Dimethomorph Dispersible Oil Suspension and Its Preparation Method and Application" (CN107114368A). The dosage of dimethomorph was 250 g / ha. The results showed that the control efficacy of the agents corresponding to Example 1, Comparative Examples 1-3 was 88.2%, 80.4%, 76.1%, and 69.8% respectively 7 days after two applications.

[0034] Table 1

[0035]

[0036] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a sodium lignosulfonate dispersant composition for pesticides, characterized in that, Includes the following steps: S1. Using papermaking black liquor as raw material, purified lignin is obtained through static sedimentation, flocculation sedimentation, membrane concentration, and acid precipitation. S2. Add purified lignin to water, adjust the pH of the system to 10-11 with sodium hydroxide, add hydrogen peroxide for pre-oxidation, then add formaldehyde and sodium sulfite for sulfonation reaction, followed by formaldehyde condensation reaction; after the reaction is completed, cool and discharge the material, spray dry to obtain sodium lignin sulfonate. S3. Sodium lignosulfonate and 1-ethyl-3-methylimidazolium L-lactate are added to water and stirred until homogeneous. Stevioside is added and ultrasonically treated to form a homogeneous system. The mixture is then spray-dried to obtain a pesticide-grade sodium lignosulfonate dispersant composition.

2. The method for preparing a sodium lignosulfonate dispersant composition for pesticides according to claim 1, characterized in that, In step S1, membrane concentration involves treating the filtrate after flocculation and sedimentation with a membrane to retain crude lignin with a relative molecular weight of 5000-10000, resulting in a concentrate with a solid content of 25-30%.

3. The method for preparing a sodium lignosulfonate dispersant composition for pesticides according to claim 1, characterized in that, In step S1, sulfuric acid is used for acid precipitation at 50-60℃.

4. The method for preparing a sodium lignosulfonate dispersant composition for pesticides according to claim 1, characterized in that, In step S2, during the sulfonation reaction, formaldehyde and sodium sulfite are added in a mass ratio of purified lignin to formaldehyde and sodium sulfite of 1:(0.4-1):(0.1-0.3).

5. The method for preparing a sodium lignosulfonate dispersant composition for pesticides according to claim 1, characterized in that, In step S2, the sulfonylation reaction temperature is 85-95℃ and the reaction time is 4-8h.

6. The method for preparing a sodium lignosulfonate dispersant composition for pesticides according to claim 1, characterized in that, In step S2, during the polycondensation reaction, formaldehyde is added at a mass ratio of purified lignin to formaldehyde of 1:0.1-0.

2.

7. The method for preparing a sodium lignosulfonate dispersant composition for pesticides according to claim 1, characterized in that, In step S2, the polycondensation reaction temperature is 90-100℃ and the polycondensation reaction time is 2-3h.

8. The method for preparing a sodium lignosulfonate dispersant composition for pesticides according to claim 1, characterized in that, The sodium lignosulfonate dispersant composition is made from the following raw materials in parts by weight: 90-95 parts sodium lignosulfonate, 18-22 parts 1-ethyl-3-methylimidazolium L-lactate, and 7-13 parts steviol glycosides.

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