Post-treatment process of atrazine

Abstract

The invention relates to the technical field of chemical production, and particularly discloses a post-treatment process of atrazine. The method specifically comprises the following steps: adding methanol and acetone into the atrazine reaction solution, uniformly mixing, adjusting the pH value to 1-3, heating to 40-60 DEG C, filtering, adding alkali into the obtained filtrate to adjust the pH value to 6-8, cooling to 5-20 DEG C, filtering to obtain a wet atrazine product, washing, and drying to obtain the atrazine product. According to the invention, the atrazine product with the content of more than 98.5% and snow white appearance can be obtained, and the process does not need to distill high-concentration brine and a large amount of toluene, so that about 50% of steam is saved, and the production cost of atrazine is reduced by about 3%; the atrazine is low in impurity content and toluene residue, so that subsequent preparation of pesticide preparations is facilitated; meanwhile, the compound solvent is added, so that the atrazine feed liquid is easy to filter and dry, and the whole process is free of emission of three wastes and is a low-carbon, environment-friendly, efficient and economical post-treatment process.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical production, and particularly relates to a post-treatment process for atrazine. Background Art

[0002] Atrazine, with the chemical name of 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine, is a systemic selective pre-emergence and post-emergence soil-applied herbicide. It has a relatively broad herbicidal spectrum and is suitable for controlling weeds in dryland crops such as corn, sorghum, sugarcane, fruit trees, nurseries, and forestlands. Moreover, it can be compounded with various amide herbicides such as acetochlor and metolachlor to enhance the activity and application scope of the herbicide.

[0003] Currently, the production of atrazine at home and abroad mainly adopts the toluene method synthesis process. The toluene method process is as follows: Add cyanuric chloride and toluene (weight ratio 1:4 - 5) into the reaction kettle, and add isopropylamine and 20% liquid caustic soda at -5 - 5°C for the first substitution reaction; after the first substitution reaction is qualified in the middle control, raise the temperature to 30 - 50°C, add monoethylamine and 20% liquid caustic soda for the second substitution reaction, and after the second substitution reaction is qualified in the middle control, obtain the atrazine toluene feed liquid. The reaction equation is as follows. The mass ratio of each component in the obtained atrazine toluene feed liquid is approximately sodium chloride:atrazine:water:toluene = 1:2:2:10.

[0004] First substitution reaction: Second substitution reaction:

[0005] Since the reaction system after reaction is a toluene-water system and atrazine is relatively viscous, directly cooling and filtering will clog the filter cloth. Therefore, currently, water is added for distillation to remove toluene, and then filtration and water washing are carried out to obtain atrazine. This process has the following defects: 1. The energy consumption is large, and a large amount of steam is required to remove the solvent toluene; 2. There is a solvation effect between toluene and atrazine, and it is difficult to remove it completely. There is a relatively large amount of toluene residue in the product, and it is difficult to dry; 3. The toluene in the product will affect the subsequent production of atrazine preparations; 4. By distilling out toluene, a large amount of water-insoluble colored impurities and polycondensed impurities are adsorbed on the atrazine product, making the color of atrazine dark. In actual production, the GC total area content of the obtained atrazine is only 98.5%, the internal standard content can only reach 96.5%, and the whiteness is only 85; 5. The density of atrazine is relatively light, and it is easy to have a material overflow during the process of distilling out toluene; 6. The by-product high-salt mother liquor needs to consume steam again to recover sodium chloride, and the environmental protection treatment cost is relatively high. Therefore, in order to solve the problems of low production purity and whiteness of atrazine at present, as well as high steam consumption and low process safety, it is necessary to provide a more environmentally friendly and safe post-treatment process for high-purity atrazine. Summary of the Invention

[0006] In view of the problems existing in the post-treatment process of existing atrazine, such as high energy consumption, low process safety, and low purity and appearance of the prepared atrazine product, the present invention provides a post-treatment process for atrazine.

[0007] To solve the above technical problems, the technical solution provided by the present invention is:

[0008] A post-treatment process for atrazine, comprising the following steps:

[0009] Step a, adding a composite solvent to the atrazine reaction solution, mixing evenly, adjusting the pH to 1-3, heating to 40°C-60°C, and filtering to obtain a filtrate and a crude sodium chloride product; wherein, the composite solvent includes methanol and acetone;

[0010] Step b, adding an alkali to the filtrate to adjust the pH to 6-8, cooling to 5°C-20°C, and filtering to obtain a wet atrazine product and a mother liquor;

[0011] Step c, washing the wet atrazine product with a composite solvent and drying to obtain an atrazine product.

[0012] It should be noted that the atrazine reaction solution is an atrazine reaction solution obtained by two-step amine substitution reaction of cyanuric chloride in toluene. Specifically, the atrazine reaction solution includes sodium chloride, atrazine, water and toluene in a mass ratio of 1:(1.8-2.2):(1.8-2.2):(9.8-10.2).

[0013] Compared with the prior art, through creative thinking, the present invention adds acetone and methanol to the atrazine reaction solution, forms a methanol-acetone-water system with the water in the atrazine reaction solution, and controls the pH of the system at 1-3 and the temperature at 40°C-60°C, increasing the solubility difference between atrazine and sodium chloride, colored impurities and poly-impurities in the system, so that atrazine is fully dissolved in the methanol-acetone-water system, while sodium chloride, colored impurities and poly-impurities precipitate as much as possible, and then through simple filtration, the sodium chloride and impurities in the system can be fully removed. For the filtrate after removing sodium chloride and impurities, atrazine precipitates fully under the conditions of pH 6-8 and 5°C-20°C, and through simple filtration and washing, a high-purity white atrazine product can be obtained. In addition, the present invention weakens the solvation effect of toluene and atrazine by adding a composite solvent of methanol and acetone, making the feed liquid easier to filter, and significantly reducing the toluene residue in the atrazine product. Subsequently, through washing with a composite solvent, the residual toluene solvent in the atrazine product can be fully removed, and the content of the prepared atrazine product can reach more than 98.5%, and the chromaticity can reach more than 95, significantly improving the market competitiveness of the atrazine product.

[0014] The post-treatment process of atrazine provided by the present invention significantly reduces the steam consumption required for distilling toluene and high-salt wastewater in the traditional process, improves the post-treatment efficiency of atrazine, does not have the problem of material flushing during the post-treatment process, does not generate high-salt wastewater, reduces the environmental protection treatment cost of enterprises, is suitable for industrial production, has high economic and environmental benefits, and has extremely high promotion and application value.

[0015] Exemplarily, the preparation process of the atrazine reaction solution includes: adding cyanuric chloride and toluene with a mass ratio of (4-5):1 into a reaction kettle, adding isopropylamine and 20% liquid caustic soda at -5 to 5 °C for a mono-substitution reaction; after the mono-substitution reaction is qualified in the control, heating up to 30 to 50 °C, adding monoethylamine and 20% liquid caustic soda for a di-substitution reaction, and obtaining the atrazine reaction solution after the di-substitution is qualified in the control. The present invention has no special requirements for the preparation process of the atrazine reaction solution. Any reaction solution prepared by the conventional secondary amine substitution reaction using cyanuric chloride and toluene as raw materials in the art can adopt the above post-treatment method provided by the present invention to achieve the effects of significantly improving the yield and purity of atrazine products and improving the product appearance.

[0016] Further, in steps a and c, the volume ratio of methanol to acetone in the composite solvent is 3:1 to 7:1.

[0017] Preferably, in steps a and c, the volume ratio of methanol to acetone in the composite solvent is 3:1.

[0018] Further, in step a, the mass ratio of the composite solvent to the atrazine reaction solution is (0.5-2):1.

[0019] Preferably, in step a, the mass ratio of the composite solvent to the atrazine reaction solution is 1:1.

[0020] The preferred composite solvent and the addition amount can make atrazine fully dissolve in the system, and promote the precipitation of sodium chloride, colored impurities, polycondensed impurities, etc. Sodium chloride in the system can be removed by simple filtration, avoiding the subsequent distillation of high-salt wastewater, thereby effectively simplifying the post-treatment process and improving the treatment efficiency of the post-treatment process.

[0021] Further, in step a, after adjusting the pH to 1-3, stir for 10 min to 60 min, and then heat up to 20 °C to 60 °C.

[0022] After adding hydrochloric acid solution to adjust the pH to 1-3 and stirring for a certain time, more atrazine can be precipitated, improving the yield of atrazine.

[0023] Exemplarily, a hydrochloric acid solution with a mass concentration of 10% to 30% is used to adjust the pH of the system to 1-3.

[0024] Preferably, in step a, the pH of the system is adjusted to 2-3.

[0025] Further, in step b, the base is liquid caustic soda with a mass concentration of 10%-32%.

[0026] Preferably, in step b, liquid caustic soda is added to adjust the pH of the system to 7-8.

[0027] Preferably, in step b, the filtration temperature is 5°C - 10°C.

[0028] Further, in step c, the mass of the composite solvent used for washing is 0.05 - 0.2 times the mass of the atrazine reaction solution.

[0029] Preferably, in step c, the mass of the composite solvent used for washing is 0.1 times the mass of the atrazine reaction solution.

[0030] Further, the post-treatment process further includes: subjecting the mother liquor obtained in step b to atmospheric pressure desolvation to obtain a recovered composite solvent; separating the desolvated kettle material to obtain toluene and an aqueous phase; recycling the recovered composite solvent to step a or step c; the recovered toluene can be recycled and used as a reaction solvent in the atrazine synthesis reaction; the obtained aqueous phase can be used to dilute the caustic soda flakes used in the atrazine reaction process.

[0031] Most of the mother liquor obtained in step b is a composite solvent, toluene and water, and also contains a small amount of sodium chloride. The composite solvent therein can be recovered after atmospheric distillation. The kettle material after distillation is mainly toluene, water and sodium chloride. After liquid separation, toluene is obtained in the upper layer and a low-salt aqueous phase is obtained in the lower layer. Toluene can be directly recycled and used as a solvent for synthesizing atrazine, and the low-salt aqueous phase can be used to dilute caustic soda flakes. There is no discharge of three wastes in the whole process, which is more energy-saving and environmentally friendly.

[0032] Further, the temperature of the atmospheric distillation is 50°C - 80°C.

[0033] Further, the crude sodium chloride obtained in step a is washed with methanol to obtain white sodium chloride.

[0034] Specifically, the methanol used for washing the crude sodium chloride is 0.2 - 1 times the mass of the crude sodium chloride, preferably 0.5 times.

[0035] It should be noted that since the colored impurities and polycondensed impurities precipitated in step a are intercepted together with sodium chloride during suction filtration, the obtained crude sodium chloride is yellow wet salt. After washing with methanol, the colored impurities and polycondensed impurities entrained in the sodium chloride can be removed to obtain white sodium chloride. The methanol used for washing can be reused until the impurities accumulate and the color of the methanol becomes darker, and then it is distilled and reused.

[0036] Compared with the prior art, the advantages of the present invention are:

[0037] (1) It avoids the steps of distilling toluene and high-salt wastewater in the traditional post-treatment process. Only the composite solvent with a boiling point lower than that of toluene needs to be distilled, saving about 50% of steam consumption and reducing the production cost of atrazine by about 3% overall.

[0038] (2) After adding the composite solvent, atrazine is fully separated from colored impurities, polycondensed impurities, and sodium chloride at a specific pH and temperature, improving the content and whiteness of atrazine. The whiteness is increased to above 95, and the content is increased to above 98.5%.

[0039] (3) Adding the composite solvent weakens the solvation effect of toluene and atrazine, significantly reducing the toluene residue in the atrazine product and ensuring the quality of the subsequent atrazine formulation. Moreover, after adding the composite solvent, it is easier to filter, reducing the filtration time. At the same time, after the atrazine product is washed with the composite solvent, it is easier to dry, saving the drying time.

[0040] (4) The by-product sodium chloride has a snow-white appearance and its content can reach the first-class product level. It can be directly sold as a by-product, increasing the enterprise's income. In addition, there is no three-waste discharge in the whole process, reducing the enterprise's hazardous waste treatment cost, which conforms to the concept of energy conservation and consumption reduction and is a green production route suitable for industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is the gas chromatogram of the atrazine product prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0042] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] In the following examples and comparative examples, the detection method for the content of the atrazine product is as follows:

[0044] Gas chromatograph: It has a variable wavelength ultraviolet detector.

[0045] Chromatographic column: 15m * 0.25mm capillary column, with the inner wall coated with BD-WAX stationary liquid and a film thickness of 0.25μm;

[0046] Temperature: Column temperature 205°C, vaporization chamber 250°C, detection chamber 250°C;

[0047] Gas flow rate: Carrier gas (N2) 2.0 mL / min, hydrogen 30 mL / min, air 300 mL / min;

[0048] Injection volume: 1.0 μL;

[0049] Split ratio: 20:1;

[0050] Internal standard: Triadimefon;

[0051] Solvent: Acetone;

[0052] Among them, the peak emergence times of triadimefon and atrazine are approximately 9 min and 6 min, respectively.

[0053] In the following examples and comparative examples, the mass ratio of each component in the atrazine reaction solution is approximately sodium chloride:atrazine:water:toluene = 1:2:2:10.

[0054] Example 1

[0055] This example provides a post-treatment process for atrazine, which specifically includes the following steps:

[0056] S1. Add 200 g of atrazine reaction solution (containing 26.67 g of atrazine, 133.33 g of toluene, 13.33 g of sodium chloride, and 26.67 g of water) to a four-necked flask, start stirring, add 150 g of methanol and 50 g of acetone to the kettle, heat up to 55 °C, slowly add a hydrochloric acid solution with a mass concentration of 30%, adjust the pH to 2, stir for 30 min, and filter while it is hot to obtain a filtrate and crude sodium chloride;

[0057] The crude sodium chloride is rinsed with methanol, and the methanol used for rinsing is 0.5 times the mass of the crude sodium chloride to obtain snow-white sodium chloride;

[0058] S2. Cool the filtrate to 15 °C, add a liquid alkali with a mass concentration of 32% to adjust the pH to 7, cool to 5 °C and filter to obtain wet atrazine and mother liquor;

[0059] S3. The wet atrazine is rinsed with 20 g of methanol and acetone with a mass ratio of 3:1, dried, and 26.57 g of atrazine product is obtained. The GC full area content is 99.5%, the internal standard content is 98.60%, the appearance is snow-white, and the whiteness is 95.6;

[0060] S4. Heat the mother liquor to 60 - 70 °C, distill it under normal pressure until no distillate is collected, collect the distillate to obtain a mixed solution of methanol and acetone, separate the kettle material, and obtain 132.55 g of toluene phase and 42.05 g of water phase on the upper layer.

[0061] Example 2

[0062] This example provides a post-treatment process for atrazine, which specifically includes the following steps:

[0063] S1. Add 200 g of atrazine reaction solution (containing 26.67 g of atrazine, 133.33 g of toluene, 13.33 g of sodium chloride, and 26.67 g of water) into a four-necked flask. Start stirring, add 320 g of methanol and 80 g of acetone into the flask, heat up to 60 °C, slowly add a hydrochloric acid solution with a mass concentration of 30%, adjust the pH to 3, stir for 60 min, and filter while it is hot to obtain a filtrate and crude sodium chloride;

[0064] The crude sodium chloride is rinsed with methanol, and the methanol used for rinsing is 0.2 times the mass of the crude sodium chloride to obtain snow-white sodium chloride;

[0065] S2. Cool the filtrate to 30 °C, add a liquid alkali with a mass concentration of 32% to adjust the pH to 8, cool to 20 °C and filter to obtain wet atrazine and mother liquor;

[0066] S3. The wet atrazine is rinsed with 10 g of methanol and acetone with a mass ratio of 4:1, dried, to obtain 26.55 g of atrazine product, with a GC full area content of 99.3%, an internal standard content of 98.58%, a snow-white appearance, and a whiteness of 95.5;

[0067] S4. Heat the mother liquor to 60 - 70 °C, distill it at atmospheric pressure until no distillate is collected, collect the distillate to obtain a methanol and acetone mixed solution, separate the kettle material by liquid separation, and obtain 132.08 g of toluene phase and 42.58 g of water phase on the upper layer.

[0068] Example 3

[0069] This example provides a post-treatment process for atrazine, which specifically includes the following steps:

[0070] S1. Add 200 g of atrazine reaction solution (containing 26.67 g of atrazine, 133.33 g of toluene, 13.33 g of sodium chloride, and 26.67 g of water) into a four-necked flask. Start stirring, add 87 g of methanol and 13 g of acetone into the flask, heat up to 40 °C, slowly add a hydrochloric acid solution with a mass concentration of 30%, adjust the pH to 1, stir for 10 min, and filter while it is hot to obtain a filtrate and crude sodium chloride;

[0071] The crude sodium chloride is rinsed with methanol, and the methanol used for rinsing is 1 times the mass of the crude sodium chloride to obtain snow-white sodium chloride;

[0072] S2. Cool the filtrate to 20 °C, add a liquid alkali with a mass concentration of 32% to adjust the pH to 6, cool to 10 °C and filter to obtain wet atrazine and mother liquor;

[0073] S3. The wet atrazine is rinsed with 40 g of methanol and acetone with a mass ratio of 7:1, dried, to obtain 26.54 g of atrazine product, with a GC full area content of 99.2%, an internal standard content of 98.55%, a snow-white appearance, and a whiteness of 95.2;

[0074] S4. Heat the mother liquor to 60 - 70 °C and distill it at atmospheric pressure until no more distillate is collected. Collect the distillate to obtain a mixed solution of methanol and acetone. Separate the material in the kettle. The upper layer yields 133.01 g of toluene phase and 41.59 g of aqueous phase.

[0075] The sodium chloride prepared in the above examples meets the national standard of GB / T 5462 - 2015 "Industrial Salt" and can be directly sold as a sodium chloride product. The toluene phase can be directly recycled as a solvent for the atrazine synthesis reaction, and the aqueous phase can be directly used as a diluent for the caustic soda to be added in the atrazine synthesis reaction. The recovered toluene can be recycled to steps S1 and S3 for reuse, and the methanol for washing the sodium chloride can also be reused as a washing solution.

[0076] Comparative Example 1

[0077] This comparative example provides a post - treatment process for atrazine, which specifically includes the following steps:

[0078] Add 200 g of atrazine reaction solution (containing 26.67 g of atrazine, 133.33 g of toluene, 13.33 g of sodium chloride, and 26.67 g of water) to a four - necked flask. Start stirring, add 100 g of water to the kettle, heat to 100 - 105 °C until no more toluene is collected, and perform suction filtration to obtain wet atrazine; add 50 g of water to wash the filter cake, and dry the filter cake to obtain 26.04 g of atrazine product, with a GC total area content of 98.9%, an internal standard content of 96.50%, a white appearance, and a whiteness of 85.5.

[0079] Comparative Example 2

[0080] This comparative example provides a post - treatment process for atrazine. The only difference from Example 1 is that the composite solvent in S1 is replaced with methanol single solvent. The specific steps are as follows:

[0081] S1. Add 200 g of atrazine reaction solution (containing 26.67 g of atrazine, 133.33 g of toluene, 13.33 g of sodium chloride, and 26.67 g of water) to a four - necked flask. Start stirring, add 200 g of methanol to the kettle, heat to 55 °C, slowly add a hydrochloric acid solution with a mass concentration of 30%, adjust the pH to 2, and stir for 30 min. Then filter while it is hot to obtain a filtrate;

[0082] S2. Cool the filtrate to 15 °C, add a liquid caustic soda with a mass concentration of 32% to adjust the pH to 7, and cool to 5 °C for filtration to obtain wet atrazine and mother liquor;

[0083] S3. Wash the wet atrazine product with 20 g of methanol and acetone with a mass ratio of 3:1, and dry it to obtain 26.50 g of atrazine product, with a GC total area content of 99.8%, an internal standard content of 96.53%, a snow - white appearance, and a whiteness of 94.6;

[0084] S4. Heat the mother liquor to 60 - 70 °C, distill it at atmospheric pressure until no more distillate is collected, collect the distillate to obtain a mixed solution of methanol and acetone, separate the kettle material by liquid separation, and obtain 132.16 g of toluene phase and 42.34 g of aqueous phase in the upper layer.

[0085] Comparative Example 3

[0086] This comparative example provides a post - treatment process for atrazine. The only difference from Example 1 is that the composite solvent in S1 is replaced with acetone single solvent, and the specific steps are as follows:

[0087] S1. Add 200 g of atrazine reaction solution (containing 26.67 g of atrazine, 133.33 g of toluene, 13.33 g of sodium chloride, and 26.67 g of water) to a four - necked flask, start stirring, add 200 g of acetone to the kettle, heat to 55 °C, slowly add a hydrochloric acid solution with a mass concentration of 30%, adjust the pH to 2, stir for 30 min, and filter while it is hot to obtain a filtrate.

[0088] S2. Cool the filtrate to 15 °C, add a liquid alkali with a mass concentration of 32% to adjust the pH to 7, cool to 5 °C and filter to obtain wet atrazine and mother liquor.

[0089] S3. Wash the wet atrazine product with 20 g of a methanol - acetone mixture with a mass ratio of 3:1, dry it to obtain 26.04 g of atrazine product, with a GC total area content of 99.5%, an internal standard content of 98.8%, a snow - white appearance, and a whiteness of 95.6.

[0090] S4. Heat the mother liquor to 60 - 70 °C, distill it at atmospheric pressure until no more distillate is collected, collect the distillate to obtain a mixed solution of methanol and acetone, separate the kettle material by liquid separation, and obtain 133.25 g of toluene phase and 41.14 g of aqueous phase in the upper layer.

[0091] The yields, purities, and whitenesses of the atrazine products prepared in Examples 1 - 3 and Comparative Examples 1 - 3 are compared as shown in Table 1.

[0092] Table 1

[0093] Group Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Yield (%) 98.24 98.15 98.07 94.23 95.91 96.47 Content (%) 98.60 98.58 98.55 96.50 96.53 98.8 Whiteness 95.6 95.5 95.2 85.5 94.6 95.6

[0094] It can be seen from the results that the contents of the atrazine products prepared in Examples 1 - 3 are all above 98.5%, and the whiteness reaches above 95. Compared with Comparative Examples 1 - 3, the quality and yield of atrazine are significantly improved.

[0095] In summary, the post-treatment process for atrazine provided by the present invention is simple and efficient, and can obtain an atrazine product with a content greater than 98.5% and a snow-white appearance. Moreover, this process does not require distilling high-concentration brine and a large amount of toluene, saving approximately 50% of steam and reducing the production cost of atrazine by about 3%. The atrazine obtained by this process has few impurities and little toluene residue, which is beneficial for the subsequent preparation of pesticide formulations, and the obtained pesticide formulation products have better stability. At the same time, adding a composite solvent makes the atrazine feed liquid easy to filter and dry, and the dried atrazine product is not easy to stick to the bag. In addition, the entire process of the present invention has no three-waste emissions, is a low-carbon, environmentally friendly, efficient and economical post-treatment process, helps enterprises reduce costs and increase efficiency, and has high practical value.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A post-treatment process of atrazine, characterized in that: The raw material is an atrazine reaction solution obtained by a two-step amine substitution reaction of cyanuric chloride in toluene, wherein the atrazine reaction solution comprises sodium chloride, atrazine, water and toluene, and the post-treatment process comprises the following steps: Step a, adding a composite solvent to the atrazine reaction solution, mixing evenly, adjusting the pH to 1-3, heating to 40° C.-60° C., filtering to obtain a filtrate and a crude sodium chloride product; wherein the composite solvent comprises methanol and acetone; Step b, adding alkali to the filtrate to adjust the pH to 6-8, cooling to 5°C-20°C, filtering to obtain atrazine wet product and mother liquor; Step c, washing the wet atrazine product with a composite solvent, and drying to obtain an atrazine product.

2. The post-treatment process of atrazine according to claim 1, characterized in that: In step a, the atrazine reaction solution comprises sodium chloride, atrazine, water and toluene in a mass ratio of 1:(1.8-2.2):(1.8-2.2):(9.8-10.2).

3. The post-treatment process of atrazine according to claim 1, characterized in that: In step a and step c, the volume ratio of methanol to acetone in the composite solvent is 3:1 to 7:

1.

4. The post-treatment process of atrazine according to claim 1 or 3, characterized in that: In step a, the mass ratio of the composite solvent to the atrazine reaction solution is (0.5-2):

1.

5. The post-treatment process of atrazine according to claim 1, characterized in that: In step a, after adjusting the pH to 1-3, stirring for 10-60 minutes, and then heating to 20-60°C.

6. The post-treatment process of atrazine according to claim 1, characterized in that: In step b, the alkali is liquid alkali with a mass concentration of 10% to 32%.

7. The post-treatment process of atrazine according to claim 1, characterized in that: In step c, the mass of the composite solvent used for washing is 0.05 to 0.2 times the mass of the atrazine reaction solution.

8. The post-treatment process of atrazine according to claim 1, characterized in that: The post-treatment process also includes: desolventizing the mother liquor obtained in step b at normal pressure to obtain a recovered composite solvent; and separating the kettle material after desolventizing to obtain toluene and water phase.

9. The post-treatment process of atrazine according to claim 8, characterized in that: The recovered composite solvent is recycled and applied to step a or step c; the recovered toluene and water phase are applied to the atrazine synthesis process; and / or The temperature of the atmospheric distillation is 50°C to 80°C.

10. The post-treatment process of atrazine as claimed in claim 1, characterized in that: The crude sodium chloride obtained in step a is washed with methanol to obtain white sodium chloride.

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