A method of recycling of pyriproxyfen

Abstract

The present application relates to the technical field of pesticide production waste resource, in particular to a method for recovering pyridyl quinolinyl. The method uses wastewater containing pyridyl quinolinyl produced in the crystallization process of pyridyl quinolinyl as raw material, and combines the processes of concentration, solvent extraction and stepwise cooling crystallization to efficiently recover and purify the residual pyridyl quinolinyl in the waste liquid under the condition of accurately controlling the cooling stage and the cooling rate. The purity of the recovered product is higher than 95.0%, reaching the national standard of pyridyl quinolinyl technical material, and can be directly used for pesticide preparation production. The method improves the resource utilization efficiency, reduces the waste discharge and treatment cost, has obvious economic and environmental benefits, and is suitable for industrial application.

Description

Technical Field

[0001] This invention relates to the field of pesticide production waste resource utilization technology, specifically to a method for recovering quizalofop-p-ethyl. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Quizalofop-P-ethyl, a typical representative of aryloxyphenoxypropionate herbicides, is widely used for the control of grassy weeds in broadleaf crop fields such as soybeans, cotton, and sugar beets due to its outstanding advantages of high efficiency, low toxicity, and high selectivity, occupying an important position in modern agricultural production. However, the industrial synthesis of quizalofop-P-ethyl generates a large amount of process waste liquid per ton of product. This waste liquid has a complex composition and is highly toxic, containing not only residual quizalofop-P-ethyl but also various reaction byproducts and intermediates, making its treatment extremely difficult.

[0004] Traditional methods for treating this type of waste liquid focus on "harmlessness," primarily employing biochemical and oxidation processes to degrade pollutants. While these methods meet environmental emission standards, they fail to recover the valuable quizalofop-p-ethyl components from the waste liquid, resulting in severe structural waste of resources. With the increasing popularity of green chemistry and circular economy concepts, the resource utilization of pesticide production waste liquid has become a crucial direction for industry transformation and upgrading, and recycling technologies that combine environmental protection and economic value are attracting significant attention.

[0005] Existing research on the resource recovery of wastewater from quizalofop-P-ethyl production mainly focuses on the recovery of inorganic byproducts, which has significant technical limitations. For example, patent CN106809836A discloses a method for refining potassium carbonate from quizalofop-P-ethyl byproducts, which only achieves the recovery and reuse of inorganic components; patent CN116282291A addresses the sulfur-containing wastewater generated in the quizalofop-P-ethyl salt-forming process by recovering sodium hydrosulfide through acid adjustment and sodium hydroxide absorption, and then reusing it in the salt-forming process to reduce raw material consumption and improve sulfur utilization. The mother liquor generated during crystallization in the existing quizalofop-P-ethyl preparation process contains some impurities generated during synthesis and also contains a significant amount of quizalofop-P-ethyl; direct discharge of this liquor would severely pollute the environment. However, none of the above solutions address the efficient recovery and purification of the main organic component in the wastewater—quizalofop-P-ethyl. Currently, there is no mature technology in this field capable of efficiently recovering high-purity quizalofop-P-ethyl from quizalofop-P-ethyl production wastewater, making it difficult to simultaneously achieve environmental compliance and resource recovery benefits. Therefore, developing an efficient, green, and industrially compatible method for the resource recovery of quizalofop-p-ethyl waste liquid has become a key technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a method for recovering quizalofop-P-ethyl, achieving efficient recovery and purification of quizalofop-P-ethyl through optimized extraction and crystallization processes.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for recovering quizalofop-p-ethyl comprises the following steps: (1) The waste liquid containing quizalofop-P-ethyl was concentrated to obtain a solid; (2) The solid obtained in step (1) is added to organic solvent A, heated and stirred at 40~45 °C for 1~2 h, filtered while hot to remove insoluble impurities, the filtrate is collected and concentrated to obtain a preliminarily purified solid; (3) The solid obtained in step (2) is added to organic solvent B, heated and stirred at 50~60 °C for 1~2 h, filtered while hot, and the clear filtrate of quizalofop-p-ethyl is collected. (4) The filtrate collected in step (3) is subjected to step-by-step cooling crystallization, which is the core step of the present invention, and specifically includes: A: Control the temperature of the filtrate at 58~62 ℃, then slowly cool it down to 42~45 ℃ at a rate of 6~10 min / ℃. Stir and keep it warm for 1~3 h at 150~300 rpm, then filter to precipitate and remove high melting point impurities, and collect the filtrate. B: Cool the filtrate collected in step (4) A to 30-38 ℃ at a rate of 3-5 min / ℃, stir at 150-300 rpm and keep warm for 1-3 h, then filter to further remove some impurities with medium melting point and collect the filtrate. C: Cool the filtrate collected in step (4) B to 20-25 °C at a rate of 6-10 min / ℃, and keep it aged for 1-3 h at a stirring rate of 500-800 rpm to allow the target product, quizalofop-p-ethyl, to precipitate out in large quantities and in an orderly manner, thus obtaining high-purity crystals.

[0008] (5) Filter the solid-liquid mixture obtained in step (4) C, collect the solid, and dry it at 45~60 ℃ for 12~14 h to obtain the recovered quizalofop-p-ethyl.

[0009] Further, the waste liquid containing quizalofop-p-ethyl in step (1) is derived from a solution synthesized by esterification of (R)-2-[4-(6-chloroquinoxaloline-2-yloxy)]propionate and haloethane. An alcohol solvent is added to the solution for recrystallization, and the filtrate after crystallization is the waste liquid containing quizalofop-p-ethyl. The content of quizalofop-p-ethyl in the waste liquid is 5%~10%.

[0010] Furthermore, the concentration temperature in both steps (1) and (2) is 40~45 ℃ to prevent the decomposition of quizalofop-p-ethyl due to high temperature.

[0011] Further, the organic solvent A is one or more of ethyl acetate, methyl acetate, ethyl formate, propyl acetate, and isopropyl acetate.

[0012] Furthermore, the mass ratio of organic solvent A to the solid obtained in step (1) is 20~30:1, which can effectively dissolve the target substance and wash away most of the impurities.

[0013] Furthermore, the organic solvent B is selected from one or more of petroleum ether, n-hexane, n-heptane, C1-C4 alcohols, C3-C4 ketones, acetonitrile, tetrahydrofuran, and dioxane.

[0014] Furthermore, the mass ratio of organic solvent B to the solid obtained in step (2) is 1~3:1.

[0015] Furthermore, in steps (4)A and (4)B, the stirring rate during the cooling process is controlled to be 150~300 rpm.

[0016] Furthermore, the drying conditions in step (5) are drying at 45~60 ℃ for 12~14 h.

[0017] The beneficial effects of the technical solution provided by this invention are: 1. This invention employs a synergistic process of secondary solvent extraction and step-cooling crystallization to effectively separate impurities. The HPLC purity of the recovered quizalofop-p-ethyl is consistently above 95.0%, which meets the requirements of the People's Republic of China Agricultural Industry Standard (NY / T 3594-2020) for the mass fraction of quizalofop-p-ethyl technical grade (≥95.0%). It can be directly used as a raw material for pesticide production without secondary purification, significantly enhancing the economic value of the recovered product.

[0018] 2. This invention realizes the resource utilization of waste liquid from the production of quizalofop-P-ethyl, transforming "waste" in the traditional sense into qualified production raw materials, reducing the generation and disposal costs of solid waste from the source, lowering the difficulty of waste liquid treatment, conforming to the development concept of green chemistry and circular economy, and having both environmental and social benefits.

[0019] 3. The organic solvents A and B used in this invention are both green and environmentally friendly, and can be recovered and reused through concentration processes, resulting in low solvent loss. The process is simple, requires no complex equipment, and has low energy consumption in cooling, drying, and other stages. It is easy to operate and control, with significant overall cost advantages. It has the conditions for large-scale industrial application and provides a practical and feasible technical solution for the resource utilization of waste from the production of quizalofop-P-ethyl. Attached Figure Description

[0020] Figure 1 The HPLC chromatogram of Example 1; Figure 2 The XRD pattern of Example 1; Figure 3 This is the DSC spectrum of Example 1. Detailed Implementation

[0021] The specific embodiments of the present invention are described in detail below. These embodiments are intended to more fully demonstrate the technical content of the present invention and help to understand the specific implementation process of the present invention, but their content should not be construed as limiting the scope of the claims of the present invention in any way. For those skilled in the art, various adjustments, modifications, and substitutions made to the embodiments without departing from the spirit and scope of the present invention are all within the scope of protection sought by the present invention.

[0022] The waste liquid containing quizalofop-P-ethyl comes from the following: quizalofop-P-ethyl crude product is synthesized by esterification reaction of (R)-2-[4-(6-chloroquinoxaloline-2-yloxy)]propionate and haloethane, and then purified by recrystallization with alcohol solvent. The filtrate of this waste liquid contains 5%~10% quizalofop-P-ethyl.

[0023] Example 1 (1) Take the mother liquor containing 5% quizalofop-P-ethyl and concentrate it at 45 °C to obtain a solid.

[0024] (2) Take 100 g of the above solid and add it to 2500 mL of methyl acetate. Stir at 45 °C for 2 h at a stirring speed of 200 rpm. Then filter while hot, collect the filtrate, and concentrate it at 45 °C to obtain the solid.

[0025] (3) Add the concentrated solid to 100 mL of petroleum ether, stir at 55 °C for 1 h at a stirring speed of 200 rpm, then filter while hot and collect the filtrate.

[0026] (4) The filtrate collected in step (3) is subjected to step-cooling crystallization, specifically including: A. Transfer the filtrate to a crystallizer and equilibrate at 60 °C for 30 min. Then, cool to 42 °C at a rate of 9 min / °C while stirring at 200 rpm. After cooling, continue stirring at a constant temperature for 1 h, filter while hot, and collect the filtrate. B. Incubate the filtrate at 42 °C for 30 min to equilibrate, then cool it to 30 °C at a rate of 3 min / °C while stirring at 150 rpm. After cooling, continue stirring at a constant temperature for 1 h, filter while hot, and collect the filtrate; C. Incubate the filtrate at 30 °C for 30 min to equilibrate, then cool it to 25 °C at a rate of 8 min / °C while stirring at 500 rpm. Continue stirring at a constant temperature for 2 h after cooling is complete.

[0027] (5) Filter, collect the solid, and dry at 60 °C for 12 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 75%, and the HPLC purity was 97.38%.

[0028] Example 2 (1) Take the mother liquor containing 5% quizalofop-P-ethyl and concentrate it at 40 °C to obtain a solid.

[0029] (2) Take 100 g of the above solid and add it to 2000 mL of ethyl formate. Stir at 40 °C for 2 h at a stirring speed of 150 rpm. Then filter while hot, collect the filtrate, and concentrate it at 40 °C to obtain the solid.

[0030] (3) Add the concentrated solid to 150 mL of acetone, stir at 50 °C for 2 h at a stirring speed of 150 rpm, then filter while hot and collect the filtrate.

[0031] (4) The filtrate collected in step (3) is subjected to step-cooling crystallization, specifically including: A. Transfer the filtrate to a crystallizer and equilibrate at 58 °C for 30 min. Then, cool to 43 °C at a rate of 8 min / °C while stirring at 150 rpm. After cooling, continue stirring at the same temperature for 2 h. Filter while hot and collect the filtrate. B. Incubate the filtrate at 43 °C for 30 min to equilibrate, then cool it to 35 °C at a rate of 4 min / °C while stirring at 300 rpm. After cooling, continue stirring at a constant temperature for 3 h, filter while hot, and collect the filtrate; C. Incubate the filtrate at 35 °C for 30 min to equilibrate, then cool it to 20 °C at a rate of 10 min / °C while stirring at 800 rpm. Continue stirring at a constant temperature for 1 h after cooling is complete.

[0032] (5) Filter, collect the solid, and dry at 50 °C for 12 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 78%. The HPLC purity of the product was 95.37%.

[0033] Example 3 (1) Take the mother liquor containing 10% quizalofop-P-ethyl and concentrate it at 40 °C to obtain a solid.

[0034] (2) Take 100 g of the above solid and add it to 2500 mL of ethyl acetate. Stir at 40 °C for 1 h at a stirring speed of 300 rpm. Then filter while hot, collect the filtrate, and concentrate it at 40 °C to obtain the solid.

[0035] (3) Add the concentrated solid to 300 mL of isopropanol, stir at 60 °C for 1 h at a stirring speed of 300 rpm, then filter while hot and collect the filtrate.

[0036] (4) The filtrate collected in step (3) is subjected to step-cooling crystallization, specifically including: A. Transfer the filtrate to a crystallizer and equilibrate at 58 °C for 30 min. Then, cool to 42 °C at a rate of 7 min / °C while stirring at 150 rpm. After cooling, continue stirring at a constant temperature for 1 h. Filter while hot and collect the filtrate. B. Incubate the filtrate at 42 °C for 30 min to equilibrate, then cool it to 38 °C at a rate of 4 min / °C while stirring at 150 rpm. After cooling, continue stirring at the same temperature for 2 h, filter while hot, and collect the filtrate; C. Incubate the filtrate at 38 °C for 30 min to equilibrate, then cool it to 20 °C at a rate of 7 min / °C while stirring at 600 rpm. Continue stirring at a constant temperature for 3 h after cooling is complete.

[0037] (5) Filter, collect the solid, and dry at 45 °C for 14 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 80%. The HPLC purity of the product was 96.15%.

[0038] Example 4 (1) Take the mother liquor containing 10% quizalofop-P-ethyl and concentrate it at 45 °C to obtain a solid.

[0039] (2) Take 100 g of the above solid and add it to 3000 mL of methyl acetate. Stir at 45 °C for 1 h with a stirring speed of 250 rpm. Then filter while hot, collect the filtrate, and concentrate it at 45 °C to obtain the solid.

[0040] (3) Add the concentrated solid to 250 mL of tetrahydrofuran, stir at 55 °C for 2 h at a stirring speed of 250 rpm, then filter while hot and collect the filtrate.

[0041] (4) The filtrate collected in step (3) is subjected to step-cooling crystallization, specifically including: A. Transfer the filtrate to a crystallizer and equilibrate at 61 °C for 30 min. Then, cool to 45 °C at a rate of 9 min / °C while stirring at 300 rpm. After cooling, continue stirring at a constant temperature for 3 h. Filter while hot and collect the filtrate. B. Incubate the filtrate at 45 °C for 30 min to equilibrate, then cool it to 34 °C at a rate of 3 min / °C while stirring at 200 rpm. After cooling, continue stirring at the same temperature for 3 h, filter while hot, and collect the filtrate; C. Incubate the filtrate at 34 °C for 30 min to equilibrate, then cool it to 25 °C at a rate of 6 min / °C while stirring at 700 rpm. Continue stirring at this constant temperature for 2 h after cooling is complete.

[0042] (5) Filter, collect the solid, and dry at 50 °C for 14 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 75%. The HPLC purity of the product was 97.44%.

[0043] Example 5 (1) Take the mother liquor containing 10% quizalofop-P-ethyl and concentrate it at 40 °C to obtain a solid.

[0044] (2) Take 100 g of the above solid and add it to 3000 mL of propyl acetate. Stir at 40 °C for 2 h at a stirring speed of 200 rpm. Then filter while hot, collect the filtrate, and concentrate it at 40 °C to obtain the solid.

[0045] (3) Add the concentrated solid to 150 mL of acetonitrile, stir at 60 °C for 2 h at a stirring speed of 200 rpm, then filter while hot and collect the filtrate.

[0046] (4) The filtrate collected in step (3) is subjected to step-cooling crystallization, specifically including: A. Transfer the filtrate to a crystallizer and equilibrate at 62 °C for 30 min. Then, cool to 45 °C at a rate of 10 min / °C while stirring at 200 rpm. After cooling, continue stirring at a constant temperature for 2 h. Filter while hot and collect the filtrate. B. Incubate the filtrate at 45 °C for 30 min to equilibrate, then cool it to 33 °C at a rate of 3 min / °C while stirring at 250 rpm. After cooling, continue stirring at the same temperature for 1 h, filter while hot, and collect the filtrate; C. Incubate the filtrate at 33 °C for 30 min to equilibrate, then cool it to 25 °C at a rate of 10 min / °C while stirring at 600 rpm. Continue stirring at a constant temperature for 1 h after cooling is complete.

[0047] (5) Filter, collect the solid, and dry at 60 °C for 13 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 82%. The HPLC purity of the product was 95.20%.

[0048] Example 6 (1) Take the mother liquor containing 10% quizalofop-P-ethyl and concentrate it at 45 °C to obtain a solid.

[0049] (2) Take 100 g of the above solid and add it to 2500 mL of isopropyl acetate. Stir at 45 °C for 2 h at a stirring speed of 150 rpm. Then filter while hot, collect the filtrate, and concentrate it at 45 °C to obtain the solid.

[0050] (3) Add the concentrated solid to 100 mL of n-propanol, stir at 50 °C for 1 h at a stirring speed of 150 rpm, then filter while hot and collect the filtrate.

[0051] (4) The filtrate collected in step (3) is subjected to step-cooling crystallization, specifically including: A. Transfer the filtrate to a crystallizer and equilibrate at 60 °C for 30 min. Then, cool to 44 °C at a rate of 6 min / °C while stirring at 250 rpm. After cooling, continue stirring at a constant temperature for 3 h. Filter while hot and collect the filtrate. B. Incubate the filtrate at 44 °C for 30 min to equilibrate, then cool it to 30 °C at a rate of 5 min / °C while stirring at 300 rpm. After cooling, continue stirring at the same temperature for 2 h, filter while hot, and collect the filtrate; C. Incubate the filtrate at 30 °C for 30 min to equilibrate, then cool it to 20 °C at a rate of 8 min / °C while stirring at 800 rpm. Continue stirring at a constant temperature for 3 h after cooling is complete.

[0052] (5) Filter, collect the solid, and dry at 50 °C for 13 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 80%. The HPLC purity of the product was 95.50%.

[0053] Comparative Example 1 This comparative example provides a method for recovering waste liquid of quizalofop-P-ethyl, which differs from Example 1 in that step S4 is reduced to a one-time cooling process, as follows: (1) Take the mother liquor containing 5% quizalofop-P-ethyl and concentrate it at 45 °C to obtain a solid.

[0054] (2) Take 100 g of the above solid and add it to 2500 mL of methyl acetate. Stir at 45 °C for 2 h at a stirring speed of 200 rpm. Then filter while hot, collect the filtrate, and concentrate it at 45 °C to obtain the solid.

[0055] (3) Add the concentrated solid to 100 mL of petroleum ether, stir at 55 °C for 1 h at a stirring speed of 200 rpm, then filter while hot and collect the filtrate.

[0056] (4) Cool the filtrate to 25 °C at a rate of 10 min / ℃ and stir at 500 rpm. Continue stirring at a constant temperature for 3 h after cooling is complete.

[0057] (5) Filter, collect the solid, and dry at 60 °C for 12 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 73%. The HPLC purity of the product was 88.69%.

[0058] Comparative Example 2 This comparative example provides a method for recovering waste liquid of quizalofop-P-ethyl, which differs from Example 1 in that the cooling rate in step S4 exceeds the range. The specific operation is as follows: (1) Take the mother liquor containing 5% quizalofop-P-ethyl and concentrate it at 45 °C to obtain a solid.

[0059] (2) Take 100 g of the above solid and add it to 2500 mL of methyl acetate. Stir at 45 °C for 2 h at a stirring speed of 200 rpm. Then filter while hot, collect the filtrate, and concentrate it at 45 °C to obtain the solid.

[0060] (3) Add the concentrated solid to 100 mL of petroleum ether, stir at 55 °C for 1 h at a stirring speed of 200 rpm, then filter while hot and collect the filtrate.

[0061] (4) The filtrate collected in step (3) is subjected to step-cooling crystallization, specifically including: A. Transfer the filtrate to a crystallizer and equilibrate at 60 °C for 30 min. Then, cool to 42 °C at a rate of 3 min / °C while stirring at 200 rpm. After cooling, continue stirring at a constant temperature for 1 h. Filter while hot and collect the filtrate. B. Incubate the filtrate at 42 °C for 30 min to equilibrate, then cool it to 30 °C at a rate of 10 min / °C while stirring at 150 rpm. After cooling, continue stirring at a constant temperature for 1 h, filter while hot, and collect the filtrate; C. Incubate the filtrate at 30 °C for 30 min to equilibrate, then cool it to 25 °C at a rate of 3 min / °C while stirring at 500 rpm. Continue stirring at a constant temperature for 2 h after cooling is complete.

[0062] (5) Filter, collect the solid, and dry at 60 °C for 12 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 75%. The HPLC purity of the product was 92.42%.

[0063] Comparative Example 3 This comparative example provides a method for recovering waste liquid of quizalofop-P-ethyl, which differs from Example 1 in that the temperature point in step S4 is outside the range. The specific operation is as follows: (1) Take the mother liquor containing 5% quizalofop-P-ethyl and concentrate it at 45 °C to obtain a solid.

[0064] (2) Take 100 g of the above solid and add it to 2500 mL of methyl acetate. Stir at 45 °C for 2 h at a stirring speed of 200 rpm. Then filter while hot, collect the filtrate, and concentrate it at 45 °C to obtain the solid.

[0065] (3) Add the concentrated solid to 100 mL of petroleum ether, stir at 55 °C for 1 h at a stirring speed of 200 rpm, then filter while hot and collect the filtrate.

[0066] (4) The filtrate collected in step (3) is subjected to step-cooling crystallization, specifically including: A. Transfer the filtrate to a crystallizer and equilibrate at 60 °C for 30 min. Then, cool to 50 °C at a rate of 9 min / °C while stirring at 200 rpm. After cooling, continue stirring at a constant temperature for 1 h. Filter while hot and collect the filtrate. B. Incubate the filtrate at 50 °C for 30 min to equilibrate, then cool it to 25 °C at a rate of 3 min / °C while stirring at 150 rpm. After cooling, continue stirring at a constant temperature for 1 h, filter while hot, and collect the filtrate; C. Incubate the filtrate at 25 °C for 30 min to equilibrate, then cool it to 10 °C at a rate of 8 min / °C while stirring at 500 rpm. Continue stirring at a constant temperature for 2 h after cooling is complete.

[0067] (5) Filter, collect the solid, and dry at 60 °C for 12 h to obtain the quizalofop-p-ethyl recovery product. The product yield was 74%. The HPLC purity of the product was 90.63%.

[0068] Figure 1 The figure shows the HPLC chromatogram of Example 1. The HPLC purity of the recovered quizalofop-p-ethyl obtained in Example 1 is 97.38%, which proves that the recovery process of the present invention can effectively remove impurities in the waste liquid and make the product purity reach the standard of the original drug. Figure 2 The XRD pattern shows that the characteristic peaks of the recovered quizalofop-P-ethyl have diffraction angles of 8.58°, 10°, 11.85°, 12.93°, 15.06°, 16.23°, 17.31°, 18.83°, 20.11°, 21.5°, 22.77°, 24.82°, 28.3°, 29°, and 30.55°, exhibiting a single crystal morphology. This demonstrates the high purity of the product and ensures its stability, reducing the impact of impurities on the stability of the formulation and facilitating subsequent formulation processing and development. Figure 3The DSC spectrum shows that the product has a single, sharp melting point and a standard calorific value, with a melting point of 74.86 ℃, which is consistent with the characteristics of R-quizalofop-p-ethyl, indicating that quizalofop-p-ethyl has high optical purity.

[0069] Comparative Example 1 used a single, uniform cooling process, resulting in the simultaneous precipitation of impurities and quizalofop-P-ethyl, leading to a product purity of only 88.69%, which failed to meet the original drug standard. In Comparative Example 2, segmented cooling was used, but its cooling rate exceeded the preferred range described in this invention, resulting in a failure to selectively separate impurities from the target product, leading to a low purity of quizalofop-P-ethyl in the final product (92.42%). Comparative Example 3's cooling temperature was outside the range, resulting in a significant decrease in the purity of the final product (90.63%).

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering quizalofop-p-ethyl, characterized in that, The method comprises the following steps: (1) Concentrate the waste liquid containing quizalofop-P-ethyl to obtain solid a; (2) Mix the solid a obtained in step (1) with organic solvent A, heat and stir, filter, collect the filtrate and concentrate to obtain solid b; (3) Mix the solid b obtained in step (2) with organic solvent B, heat and stir, then filter and collect the filtrate; (4) Heat the filtrate obtained in step (3) and then cool it down in a stepwise manner to obtain the recovered quizalofop-p-ethyl.

2. The method according to claim 1, characterized in that, The heating temperature in step (4) is 58~62 ℃.

3. The method according to claim 1, characterized in that, Step (4) specifically includes the following steps: A. Cool the filtrate to 42-45 °C at a rate of 6-10 min / ℃, stir for 1-3 h, filter, and collect the filtrate; B. Cool the filtrate obtained in step (4) A to 30-38 °C at a rate of 3-5 min / ℃, stir for 1-3 h, filter, and collect the filtrate; C. Reduce the filtrate obtained in step (4) B to 20-25 °C at a rate of 6-10 min / ℃, stir for 1-3 h, filter and collect the solid to obtain the quizalofop-p-ethyl recovery product.

4. The method according to claim 1, characterized in that, In step (2), organic solvent A is one or more of ethyl acetate, methyl acetate, ethyl formate, propyl acetate, and isopropyl acetate.

5. The method according to claim 1, characterized in that, In step (2), the volume-to-mass ratio of organic solvent A to solid a is (20~30) mL:1 g.

6. The method according to claim 1, characterized in that, The organic solvent B in step (3) is one of petroleum ether, n-hexane, n-heptane, C1~C4 alcohols, C3~C4 ketones, acetonitrile, tetrahydrofuran, and dioxane.

7. The method according to claim 1, characterized in that, In step (3), the volume-to-mass ratio of organic solvent B to solid b is (1~3) mL:1g.

8. The method according to claim 1, characterized in that, The concentration temperature in both steps (1) and (2) is 40~45 ℃.

9. The method according to claim 1, characterized in that, The heating and stirring described in step (2) is carried out at 40~45 ℃ and at a speed of 150~300 rpm for 1~2 h.

10. The method according to claim 1, characterized in that, The heating and stirring described in step (3) is carried out at 50~60 ℃ and at a speed of 150~300 rpm for 1~2 h.

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