Indoxacarb post-treatment process

Abstract

The invention relates to the technical field of chemical purification of pesticides, and particularly discloses a post-treatment process of indoxacarb. According to the process, metal ions, colored impurities and byproducts in reaction liquid are deeply removed by adopting a composite adsorbent composed of chelate resin loaded nano zinc oxide and beta-cyclodextrin; a high-purity crystal is obtained by combining a mixed solvent with ultrasonic-assisted gradient crystallization; and further treating by using a melting sweating technology under nitrogen protection, and dehydrating crystallization mother liquor through a molecular sieve to realize high-efficiency recovery of the mixed solvent. The purity and quality stability of indoxacarb are remarkably improved and the production cost and environmental pollution are reduced through deep impurity removal by composite adsorption, crystallization efficiency and crystal quality improvement by optimizing a solvent crystallization system, mild refining by melting sweating and efficient solvent recycling.

Description

Technical Field

[0001] This invention relates to the field of pesticide chemical purification technology, and more specifically, to a post-treatment process for indoxacarb. Background Technology

[0002] Indoxacarb, a highly effective and broad-spectrum oxadiazine insecticide, has a unique mechanism of action that rapidly inhibits insect movement and leads to death by blocking sodium ion channels in insect nerve cells. It is widely used in the control of lepidopteran pests. In its industrial synthesis, indoxacarb preparation often involves multi-step nucleophilic substitution and cyclization reactions. In addition to the target product, the reaction solution contains metal catalyst residues, unreacted raw materials, organic byproducts, and colored impurities, making the control of the product's chemical purity and physical properties a critical issue in the production process.

[0003] Traditional processes rely heavily on adsorption materials such as activated carbon and ion exchange resins. While activated carbon can adsorb some organic impurities, its ability to remove metal ions and polar impurities is limited, and it suffers from poor adsorption selectivity and loss of target products. Ion exchange resins, although capable of chelating metal ions, struggle to simultaneously remove colored substances and high-molecular-weight byproducts, leading to impurities easily encapsulating crystals during subsequent crystallization, affecting purity. Furthermore, different crystallization conditions cause indoxacarb to easily form fine crystals or aggregates, reducing filtration efficiency and resulting in an excessively wide crystal size distribution, impacting formulation processing performance. Chinese patent CN116808857A employs a multi-stage filtration device to improve crystallization purity, but it still suffers from drawbacks such as a lengthy process flow, high equipment investment, and large amounts of waste. Therefore, this invention provides an indoxacarb post-treatment process to address the aforementioned technical problems. Summary of the Invention

[0004] The purpose of this invention is to provide a post-processing technology for indoxacarb, which significantly improves the purity and quality stability of indoxacarb and reduces production costs and environmental pollution by using composite adsorption for deep impurity removal, optimizing the solvent crystallization system to improve crystallization efficiency and crystal quality, using melting and sweating for gentle refining, and using efficient solvent recovery and recycling.

[0005] This invention provides a post-treatment process for indoxacarb, employing the following technical solution:

[0006] A post-treatment process for indoxacarb includes the following steps:

[0007] S1. Filter the reaction solution containing indoxacarb to obtain filtrate I. Add a composite adsorbent to filtrate I, stir at 40-50℃ for 2-3 hours, filter, wash and distill under reduced pressure to obtain filtrate II. The composite adsorbent is composed of chelated resin-supported nano zinc oxide and β-cyclodextrin.

[0008] S2. Add mixed solvent to filtrate II, gradually cool from 55-65℃ to -10-0℃, and simultaneously apply ultrasonic-assisted dispersion at 30-50kHz. Filter to obtain indoxacarb crystals and crystallization mother liquor.

[0009] S3. Melt the indoxacarb crystals obtained in S2 at 115-125℃ under nitrogen protection, cool to 75-85℃ at a rate of 0.8-1.2℃ / min and maintain the temperature for 1-3 hours to allow the liquid phase to separate out impurities.

[0010] S4. After dehydrating the mother liquor of S2 crystallization through a molecular sieve, the mixed solvent is recovered and separated by vacuum distillation.

[0011] Preferably, the composite adsorbent in step S1 is prepared through the following steps:

[0012] (1) Soak the chelating resin in 0.3-0.5 mol / L hydrochloric acid solution for 2-4 h and wash until neutral. Then, it is coupled with 10-50 nm nano zinc oxide and coupling agent dispersed in anhydrous ethanol at 40-50 °C for 3-5 h. Filter and dry.

[0013] (2) Dissolve β-cyclodextrin in phosphate buffer solution with pH=8-9, add crosslinking agent, and perform grafting reaction with the product obtained in step (1) at 40-60℃ for 6-8h. The product is then obtained by gradient washing and vacuum drying.

[0014] Preferably, in step S1, the components are 100-110 parts by weight of filtrate I and 5-8 parts by weight of composite adsorbent, wherein the chelating resin is an aminophosphate chelating resin.

[0015] Preferably, in step S2, the mixture consists of 10-15 parts by weight of filtrate II and 8-12 parts by weight of mixed solvent, wherein the mixed solvent is composed of isopropyl acetate and 1-butyl-3-methylimidazolium acetate in a mass ratio of 3-5:1.

[0016] Preferably, the molecular sieve in step S4 is at least one of type 3A, 4A or 5A molecular sieve.

[0017] Preferably, in step (1), the components by weight are 8-12 parts of chelating resin, 35-40 parts of hydrochloric acid solution, 70-80 parts of anhydrous ethanol, 1-3 parts of nano zinc oxide and 0.6-0.9 parts of coupling agent.

[0018] Preferably, the coupling agent in step (1) is at least one of the silane coupling agents KH-550, KH-560 or KH-570.

[0019] Preferably, step (2) consists of 10-15 parts by weight of β-cyclodextrin, 75-80 parts by weight of phosphate buffer, 2-5 parts by weight of crosslinking agent and 12-16 parts by weight of product from step (1), wherein the crosslinking agent is epichlorohydrin.

[0020] Preferably, step S3 satisfies the following conditions: the melting temperature is 115-125℃, the cooling rate is 0.8-1.2℃ / min, the constant temperature sweating temperature is 75-85℃, and the constant temperature sweating time is 1-3h.

[0021] In summary, the present invention has the following beneficial effects:

[0022] 1. This invention employs a composite adsorbent composed of chelating resin-loaded nano-zinc oxide and β-cyclodextrin. By utilizing the aminophosphate groups to directionally chelate residual metal ions, the nano-zinc oxide to adsorb polar byproducts, and the β-cyclodextrin to encapsulate hydrophobic colored impurities, a triple synergistic adsorption mechanism is formed. This achieves efficient and simultaneous removal of metal ions, organic byproducts, and colored impurities from the reaction solution, significantly reducing the difficulty of subsequent purification and avoiding the loss of the target product.

[0023] 2. This invention introduces a mixed solvent system of isopropyl acetate / 1-butyl-3-methylimidazolium acetate, combined with ultrasonic-assisted gradient cooling crystallization technology. It utilizes ionic liquids to regulate the interfacial tension and nucleus dispersion state, ultrasonic fields to suppress fine crystal agglomeration and enhance mass transfer efficiency, and gradient cooling to drive directional crystal growth, significantly improving crystal particle size uniformity, bulk density and filtration rate, thus providing a structural basis for high-purity crystals.

[0024] 3. This invention utilizes a melt-sweating process under nitrogen protection, employing gradient cooling to precisely control the solid-liquid phase equilibrium. It leverages the difference in melting characteristics between impurities and the main component to achieve gentle exudation separation, effectively removing eutectic impurities under oxidation-free conditions, avoiding the risk of high-temperature thermal decomposition, and fundamentally improving the chemical purity of the crystals. Through deep impurity removal via composite adsorption, optimization of the solvent crystallization system to improve crystallization efficiency and crystal quality, gentle refining via melt-sweating, and efficient solvent recovery and recycling, the purity and quality stability of indoxacarb are significantly improved, while reducing production costs and environmental pollution. Detailed Implementation

[0025] 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.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used, unless otherwise specified, were all purchased from conventional biochemical reagent stores. All quantitative experiments in the following examples were performed in triplicate, and the data are the average of the three replicates or the average ± standard deviation.

[0027] Nano zinc oxide, purchased from Hangzhou Hengge Nanotechnology Co., Ltd., model HN-J50F;

[0028] β-Cyclodextrin, purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number S11010;

[0029] Aminophosphate chelating resin, purchased from Shanghai Kaiping Resin Co., Ltd., CAS No. 39339-85-0;

[0030] 1-Butyl-3-methylimidazolium acetate, purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number S70741;

[0031] Type 3A molecular sieve, purchased from Langfang Qianyao Technology Co., Ltd., CAS No. 55465-40-2;

[0032] Type 4A molecular sieve, purchased from Langfang Qianyao Technology Co., Ltd., CAS No. 70955-01-0;

[0033] Type 5A molecular sieve, purchased from Langfang Qianyao Technology Co., Ltd., CAS No. 69912-79-4;

[0034] KH-550, purchased from Jinan Yongyue Chemical Co., Ltd., product number KH-550;

[0035] KH-560, purchased from Jinan Yongyue Chemical Co., Ltd., product number KH-560;

[0036] KH-570, purchased from Jinan Yongyue Chemical Co., Ltd., product number KH-570;

[0037] Phosphate buffer, purchased from Shanghai Xinyu Biotechnology Co., Ltd., CAS No. .

[0038] Example 1

[0039] A post-treatment process for indoxacarb includes the following steps:

[0040] S1. Filter the reaction solution containing indoxacarb to obtain filtrate I. Add 5 parts of composite adsorbent to 100 parts of filtrate I. Stir at 40℃ and 300rpm for 3h, then filter, wash and distill under reduced pressure to obtain filtrate II.

[0041] S2. Add 8 parts of mixed solvent to 10 parts of filtrate II and stir at 300 rpm to mix thoroughly. Then, start from 55℃ and gradually cool down to 0℃ at a rate of 1.5℃ / min. At the same time, apply ultrasonic-assisted dispersion at a frequency of 30kHz and a power of 150W. After filtration, indoxacarb crystals and crystallization mother liquor are obtained. The mixed solvent consists of isopropyl acetate and 1-butyl-3-methylimidazolium acetate in a mass ratio of 3:1.

[0042] S3. The indoxacarb crystals obtained in S2 were placed in a nitrogen-protected reactor and melted at 115°C. Then, the temperature was lowered to 75°C at a rate of 0.8°C / min and kept at a constant temperature for 3 hours to allow impurities to seep out of the liquid phase, thus obtaining purified indoxacarb crystals.

[0043] S4. Dehydrate the crystallization mother liquor using a 3A molecular sieve, ensuring the molecular sieve and mother liquor are in full contact for 2 hours. Then, perform vacuum distillation to recover and separate the mixed solvent. The recovered solvent can be recycled.

[0044] The composite adsorbent is prepared through the following steps:

[0045] (1) 8 parts of aminophosphoric acid chelating resin were soaked in 35 parts of 0.3mol / L hydrochloric acid solution for 4h, and then mixed with 1 part of nano zinc oxide and 0.6 parts of silane coupling agent KH-550 dispersed in 70 parts of anhydrous ethanol. The coupling reaction was carried out for 5h under stirring conditions of 40℃ and 300rpm. After the reaction was completed, the mixture was filtered and dried.

[0046] (2) Dissolve 10 parts of β-cyclodextrin in 75 parts of phosphate buffer solution with pH=8, add 2 parts of epichlorohydrin, and then add 12 parts of the product obtained in step (1). The grafting reaction is carried out for 8 hours under stirring conditions of 40℃ and 300rpm. After the reaction is completed, wash with ethanol and deionized water in sequence, and then dry under vacuum to obtain the product.

[0047] Example 2

[0048] A post-treatment process for indoxacarb includes the following steps:

[0049] S1. Filter the reaction solution containing indoxacarb to obtain filtrate I. Add 6 parts of composite adsorbent to 104 parts of filtrate I. Stir at 43℃ and 330rpm for 2.8h, then filter, wash and distill under reduced pressure to obtain filtrate II.

[0050] S2. Add 9 parts of mixed solvent to 13 parts of filtrate II and stir at 340 rpm to mix thoroughly. Then, start from 58℃ and gradually cool down to -3℃ at a rate of 1.6℃ / min. At the same time, apply ultrasonic-assisted dispersion at a frequency of 35kHz and a power of 160W. After filtration, indoxacarb crystals and crystallization mother liquor are obtained. The mixed solvent consists of isopropyl acetate and 1-butyl-3-methylimidazolium acetate in a mass ratio of 4:1.

[0051] S3. The indoxacarb crystals obtained in S2 were placed in a nitrogen-protected reactor and melted at 117°C. Then, the temperature was lowered to 77°C at a rate of 0.9°C / min and kept at a constant temperature for 2.8 hours to allow impurities to seep out of the liquid phase, thus obtaining purified indoxacarb crystals.

[0052] S4. Dehydrate the crystallization mother liquor using a 4A molecular sieve, ensuring the molecular sieve and mother liquor are in full contact for 2.2 hours. Then, perform vacuum distillation to recover and separate the mixed solvent. The recovered solvent can be recycled.

[0053] The composite adsorbent is prepared through the following steps:

[0054] (1) Nine parts of aminophosphoric acid chelating resin were soaked in 37 parts of 0.35mol / L hydrochloric acid solution for 2.5h, and then mixed with 2 parts of nano zinc oxide and 0.7 parts of silane coupling agent KH-560 dispersed in 73 parts of anhydrous ethanol. The coupling reaction was carried out at 43℃ and 330rpm for 4.8h. After the reaction was completed, the mixture was filtered and dried.

[0055] (2) Dissolve 11 parts of β-cyclodextrin in 76 parts of phosphate buffer with pH=9, add 3 parts of epichlorohydrin, and then add 13 parts of the product obtained in step (1). The grafting reaction is carried out for 7.8 h under stirring conditions of 43℃ and 320 rpm. After the reaction is completed, the product is washed with ethanol and deionized water in sequence, and then dried under vacuum to obtain the product.

[0056] Example 3

[0057] A post-treatment process for indoxacarb includes the following steps:

[0058] S1. Filter the reaction solution containing indoxacarb to obtain filtrate I. Add 8 parts of composite adsorbent to 110 parts of filtrate I. Stir at 50℃ and 450rpm for 2 hours, then filter, wash and distill under reduced pressure to obtain filtrate II.

[0059] S2. Add 12 parts of mixed solvent to 15 parts of filtrate II and stir at 450 rpm to mix thoroughly. Then, start from 65℃ and gradually cool down to -10℃ at a rate of 2℃ / min. At the same time, apply ultrasonic-assisted dispersion at a frequency of 50kHz and a power of 250W. After filtration, indoxacarb crystals and crystallization mother liquor are obtained. The mixed solvent consists of isopropyl acetate and 1-butyl-3-methylimidazolium acetate in a mass ratio of 5:1.

[0060] S3. The indoxacarb crystals obtained in S2 were placed in a nitrogen-protected reactor and melted at 125°C. Then, the temperature was lowered to 75°C at a rate of 1.2°C / min and kept at a constant temperature for 1 hour to allow impurities to seep out of the liquid phase, thus obtaining purified indoxacarb crystals.

[0061] S4. Dehydrate the crystallization mother liquor using a 5A molecular sieve, ensuring the molecular sieve and mother liquor are in full contact for 3 hours. Then, perform vacuum distillation to recover and separate the mixed solvent. The recovered solvent can be recycled.

[0062] The composite adsorbent is prepared through the following steps:

[0063] (1) 12 parts of aminophosphoric acid chelating resin were soaked in 40 parts of 0.5 mol / L hydrochloric acid solution for 4 hours, and then mixed with 3 parts of nano zinc oxide and 0.9 parts of silane coupling agent KH-570 dispersed in 80 parts of anhydrous ethanol. The coupling reaction was carried out at 50℃ and 400 rpm for 3 hours. After the reaction was completed, the mixture was filtered and dried.

[0064] (2) Dissolve 15 parts of β-cyclodextrin in 80 parts of phosphate buffer with pH=9, add 5 parts of epichlorohydrin, and then add 16 parts of the product obtained in step (1). The grafting reaction is carried out for 6 hours under stirring conditions of 60℃ and 400rpm. After the reaction is completed, the product is washed with ethanol and deionized water in sequence, and then dried under vacuum to obtain the product.

[0065] Example 4

[0066] A post-treatment process for indoxacarb includes the following steps:

[0067] S1. Filter the reaction solution containing indoxacarb to obtain filtrate I. Add 8 parts of composite adsorbent to 110 parts of filtrate I. Stir at 50℃ and 400rpm for 2.5h, then filter, wash and distill under reduced pressure to obtain filtrate II.

[0068] S2. Add 10 parts of mixed solvent to 15 parts of filtrate II and stir at 400 rpm to mix thoroughly. Then, start from 65°C and gradually cool down to -10°C at a rate of 1.8°C / min. At the same time, apply ultrasonic-assisted dispersion at a frequency of 45 kHz and a power of 240 W. After filtration, indoxacarb crystals and crystallization mother liquor are obtained. The mixed solvent consists of isopropyl acetate and 1-butyl-3-methylimidazolium acetate in a mass ratio of 4:1.

[0069] S3. The indoxacarb crystals obtained in S2 were placed in a nitrogen-protected reactor and melted at 124°C. Then, the temperature was lowered to 75°C at a rate of 1.2°C / min and kept at a constant temperature for 2 hours to allow impurities to seep out of the liquid phase, thus obtaining purified indoxacarb crystals.

[0070] S4. Dehydrate the crystallization mother liquor using a 3A molecular sieve, ensuring full contact between the molecular sieve and the mother liquor for 2.4 hours. Then, perform vacuum distillation to recover and separate the mixed solvent. The recovered solvent can be recycled.

[0071] The composite adsorbent is prepared through the following steps:

[0072] (1) 12 parts of aminophosphoric acid chelating resin were soaked in 40 parts of 0.4 mol / L hydrochloric acid solution for 2 h, and then mixed with 2 parts of nano zinc oxide and 0.8 parts of silane coupling agent KH-550 dispersed in 80 parts of anhydrous ethanol. The coupling reaction was carried out at 50 °C and 340 rpm for 3.5 h. After the reaction was completed, the mixture was filtered and dried.

[0073] (2) Dissolve 15 parts of β-cyclodextrin in 80 parts of phosphate buffer with pH=8, add 4 parts of epichlorohydrin, and then add 15 parts of the product obtained in step (1). The grafting reaction is carried out for 6 hours under stirring conditions of 60℃ and 350rpm. After the reaction is completed, the product is washed with ethanol and deionized water in sequence, and then dried under vacuum to obtain the product.

[0074] Comparative Example 1

[0075] A post-treatment process for indoxacarb differs from Example 4 in that the composite adsorbent is not used in step S1; instead, an equal amount of activated carbon is used for adsorption treatment. Other process parameters are the same as in Example 4.

[0076] Comparative Example 2

[0077] A post-treatment process for indoxacarb differs from Example 4 in that β-cyclodextrin is not used in the preparation of the composite adsorbent. Instead, the chelating resin loaded with nano-zinc oxide prepared in step (1) is used as the composite adsorbent, and the grafting process of β-cyclodextrin in step (2) is omitted. Other process parameters are the same as in Example 4.

[0078] Comparative Example 3

[0079] A post-treatment process for indoxacarb differs from Example 4 in that the loading step of nano zinc oxide is omitted in the preparation of the composite adsorbent. Specifically, step (1) of the composite adsorbent preparation is changed to soaking 12 parts of aminophosphophosphate chelating resin in 40 parts of 0.4mol / L hydrochloric acid solution for 2 hours, washing with water until neutral, and then drying directly without nano zinc oxide and coupling agent treatment; step (2) is simultaneously adjusted to dissolve 15 parts of β-cyclodextrin in 80 parts of phosphate buffer solution with pH=8, add 4 parts of epichlorohydrin, and graft it with 15 parts of the above-mentioned unloaded zinc oxide chelating resin at 60℃ and 350rpm for 6 hours. The washing and drying conditions remain unchanged, and other process parameters are the same as in Example 4.

[0080] Comparative Example 4

[0081] A post-treatment process for indoxacarb differs from Example 4 in that the composite adsorbent used in step S1 consists only of aminophosphophosphate chelating resin, omitting the nano zinc oxide loading and β-cyclodextrin grafting modification steps. Other process parameters are the same as in Example 4.

[0082] Comparative Example 5

[0083] A post-treatment process for indoxacarb differs from Example 4 in that a mixed solvent is not used in step S2; instead, an equal amount of a single isopropyl acetate solvent is used for crystallization. Other process parameters are the same as in Example 4.

[0084] Comparative Example 6

[0085] A post-processing method for indoxacarb differs from Example 4 in that the melt-sweating purification process in step S3 is omitted. That is, the indoxacarb crystals obtained in step S2 are directly used as the final product without melt-sweating treatment. Other process parameters are the same as in Example 4.

[0086] Performance testing

[0087] 1. Product purity test: The indoxacarb content was calculated using high performance liquid chromatography and external standard method, and expressed as a percentage by mass. The test results are shown in Table 1.

[0088] 2. Crystal yield: (final product quality × purity) / (theoretical mass of indoxacarb in raw material) × 100%. The test results are shown in Table 1.

[0089] 3. Solvent recovery rate: The content of each component in the recovered solvent was analyzed by gas chromatography, and the solvent recovery rate was calculated. The test results are shown in Table 1.

[0090] 4. Decolorization effect: The absorbance of filtrate II at 420 nm was measured by ultraviolet spectrophotometer. The test results are shown in Table 1.

[0091] Table 1

[0092] Test Project Product purity % Crystal yield % Solvent recovery rate % Absorbance A Example 1 98.60 88.36 92.11 0.12 Example 2 98.83 89.65 92.85 0.10 Example 3 98.55 88.18 91.70 0.15 Example 4 99.24 91.52 93.56 0.08 Comparative Example 1 96.75 79.22 88.38 0.45 Comparative Example 2 97.56 82.37 89.67 0.30 Comparative Example 3 97.24 81.50 88.95 0.25 Comparative Example 4 96.93 78.92 87.51 0.40 Comparative Example 5 97.82 83.70 90.23 0.13 Comparative Example 6 98.01 84.26 90.70 0.09

[0093] As shown in Table 1 above, in Examples 1-4, the optimized process of deep impurity removal with composite adsorbent, ultrasonic-assisted crystallization with mixed solvent, and melt sweating purification showed significantly better performance than the comparative examples in all indicators. Example 4 achieved the best decolorization effect with 99.24% purity, 91.52% crystal yield, 93.56% solvent recovery rate, and 0.08 absorbance. This is attributed to the synergistic effect of chelating resin, nano-zinc oxide, and β-cyclodextrin in its composite adsorbent, which simultaneously removes metal ions, polar byproducts, and hydrophobic pigments, creating a high-purity environment for subsequent crystallization. Simultaneously, the mixed solvent system composed of isopropyl acetate and ionic liquid, combined with ultrasonic dispersion, effectively controlled the crystal nucleation and growth kinetics, improving crystal integrity and yield.

[0094] Comparative Examples 1-6 showed a significant performance decline due to the absence of key processes or materials. In Comparative Example 1, after replacing the composite adsorbent with traditional activated carbon, the absorbance soared to 0.45, while the purity and yield decreased to 96.75% and 79.22%, respectively, confirming that it could not simultaneously remove metal ions and colored impurities. Comparative Examples 2 to 4, lacking β-cyclodextrin, nano-zinc oxide, or both, resulted in absorbance increases of 0.25-0.40 and purity decreases of 1.3%-2.3%, indicating a functional limitation of the single adsorption mechanism. In Comparative Example 5, after using a single isopropyl acetate solvent, the crystal yield decreased to 83.70%, and the solvent recovery rate decreased to 90.23%, exposing the negative impact of the absence of ionic liquid on crystallization efficiency and solvent recovery. Although Comparative Example 6 maintained good physical properties by omitting the melting and sweating step, the purity still decreased by 1.23%, proving that this step is irreplaceable for improving chemical purity.

[0095] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A post-treatment process for indoxacarb, characterized in that, Includes the following steps: S1. Filter the reaction solution containing indoxacarb to obtain filtrate I. Add a composite adsorbent to filtrate I for adsorption treatment. After filtration and washing, distill under reduced pressure to obtain filtrate II. The composite adsorbent is composed of chelating resin loaded with nano zinc oxide and β-cyclodextrin. S2. Add mixed solvent to filtrate II for gradient cooling crystallization, while applying ultrasonic-assisted dispersion, and filter to obtain indoxacarb crystals and crystallization mother liquor; S3. Melt the indoxacarb crystals obtained in S2 under nitrogen protection, and then perform isothermal sweating purification by gradient cooling. S4. After dehydrating the mother liquor of S2 crystallization through a molecular sieve, the mixed solvent is recovered and separated by vacuum distillation.

2. The indoxacarb post-treatment process according to claim 1, characterized in that, The preparation method of the composite adsorbent in step S1 includes: (1) After the chelating resin was soaked in hydrochloric acid solution, it was coupled with nano zinc oxide and a coupling agent in anhydrous ethanol; (2) Dissolve β-cyclodextrin in phosphate buffer, add crosslinking agent and perform grafting reaction with the product obtained in step (1).

3. The indoxacarb post-treatment process according to claim 1, characterized in that, In step S1, by weight, there are 100-110 parts of filtrate I and 5-8 parts of composite adsorbent, wherein the chelating resin is an aminophosphate chelating resin.

4. The indoxacarb post-treatment process according to claim 1, characterized in that, In step S2, the mixture consists of 10-15 parts by weight of filtrate II and 8-12 parts by weight of mixed solvent, wherein the mixed solvent is composed of isopropyl acetate and 1-butyl-3-methylimidazolium acetate in a mass ratio of 3-5:

1.

5. The indoxacarb post-treatment process according to claim 1, characterized in that, Step S3 meets the following conditions: the melting temperature is 115-125℃, the gradient cooling rate is 0.8-1.2℃ / min, the constant temperature sweating temperature is 75-85℃, and the constant temperature sweating time is 1-3h.

6. The indoxacarb post-treatment process according to claim 1, characterized in that, In step S4, the molecular sieve is at least one of type 3A, 4A, or 5A molecular sieve.

7. The indoxacarb post-treatment process according to claim 2, characterized in that, In step (1), the components by weight are 8-12 parts chelating resin, 35-40 parts hydrochloric acid solution, 70-80 parts anhydrous ethanol, 1-3 parts nano zinc oxide and 0.6-0.9 parts coupling agent.

8. The indoxacarb post-treatment process according to claim 2, characterized in that, In step (1), the coupling agent is at least one of the silane coupling agents KH-550, KH-560 or KH-570.

9. The indoxacarb post-treatment process according to claim 2, characterized in that, Step (2) consists of 10-15 parts by weight of β-cyclodextrin, 75-80 parts of phosphate buffer, 2-5 parts of crosslinking agent and 12-16 parts of the product from step (1), wherein the crosslinking agent is epichlorohydrin.