Recovery process of 2-mercaptobenzothiazole in ceftriaxone sodium mother liquor

Abstract

The invention discloses a recovery process of 2-mercaptobenzothiazole in a ceftriaxone sodium mother liquor, which belongs to the technical field of preparation, and comprises the following steps: adjusting the pH value of the ceftriaxone sodium mother liquor, adding activated carbon into the mother liquor, stirring, and filtering; enabling the pretreatment liquid to be in contact with a hydrophobic acidic ZIF-8 composite adsorbent; after the adsorption is completed, separating the hydrophobic acidic ZIF-8 composite adsorbent; and recrystallizing the MBT crude product, centrifugally separating and drying to obtain an MBT product. The hydrophobic acidic ZIF-8 composite adsorbent has important application value in the field of ceftriaxone sodium mother liquor treatment, not only can improve the purity of MBT, but also can realize efficient recovery of a solvent, reduce the production cost and reduce environmental pollution, and has remarkable technical advantages and practical benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of pharmaceutical preparation manufacturing, and particularly relates to a recovery process of 2-mercaptobenzothiazole in a cefotaxime sodium mother liquor. Background Art

[0002] In the synthesis process of cefotaxime sodium, the crystallization mother liquor contains the by-product 2-mercaptobenzothiazole (MBT). As an important vulcanization accelerator in the rubber industry, the recovery and utilization of MBT is of great significance for reducing production costs and environmental pollution. In the prior art, there is an MBT recovery process that adjusts the pH of the mother liquor, distills off the solvent, cools and filters, and then adds water for crystallization.

[0003] However, it still has the following key problems:

[0004] 1. The degradation products of cefotaxime sodium remaining in the mother liquor (such as sulfide impurities) are difficult to effectively separate only by high-temperature distillation and pH adjustment due to their similar physical and chemical properties to MBT. Data shows that the purity of MBT is only 98.12%-98.52%. Especially in a strong acid environment with high-concentration sulfuric acid for pH adjustment, some lipophilic impurities (such as sulfides) are prone to co-crystallize with MBT, resulting in product entrainment of impurities;

[0005] 2. In the prior art, 1-5 times the volume of the filtrate of water needs to be added to precipitate MBT, but the control of the water volume depends on experience, and the fluctuation of the water volume leads to significant differences in the yield. In addition, the solvent remaining after distillation is not completely recovered, and direct discharge poses a risk of VOCs pollution, and the remaining solvent may inhibit the uniform precipitation of MBT crystals, exacerbating the yield fluctuation. Summary of the Invention

[0006] In view of the above-mentioned disadvantages existing in the prior art, the present invention provides a recovery process of 2-mercaptobenzothiazole in a cefotaxime sodium mother liquor.

[0007] To achieve the above object, the present invention is realized through the following technical solutions:

[0008] A recovery process of 2-mercaptobenzothiazole in a cefotaxime sodium mother liquor, comprising the following steps:

[0009] S1: Adjust the pH of the cefotaxime sodium mother liquor, add activated carbon to the mother liquor, stir and then filter to remove suspended solids and organic impurities to obtain a pretreated solution;

[0010] S2: Contact the pretreated solution with a hydrophobic acidic ZIF-8 composite adsorbent, and adsorb at 20-50 °C for 30-120 min;

[0011] S3: After the adsorption is completed, separate the hydrophobic acidic ZIF-8 composite adsorbent, and desorb with an acidic desorbent for 30-180 min to obtain a desorbed solution, and apply ultrasound synchronously during desorption;

[0012] S4: The desorbing solution is concentrated to 20 - 50% of the original volume by a multi - effect evaporator, and after cooling crystallization, the crude MBT is obtained;

[0013] S5: The crude MBT is recrystallized with an ethanol - water mixed solvent, the crystallization temperature is controlled at 0 - 10 °C, and after centrifugal separation and drying, the MBT product is obtained;

[0014] The preparation method of the hydrophobic acidic ZIF - 8 composite adsorbent comprises the following steps:

[0015] A. Zn(NO3)2·6H2O and 2 - methylimidazole are dissolved in methanol according to a molar ratio of 1:5 - 20, and a solvothermal reaction is carried out at 50 - 80 °C to obtain ZIF - 8 nanoparticles;

[0016] B. The ZIF - 8 nanoparticles doped with rare - earth metal oxides are dispersed in ethanol, a silane coupling agent is added, and a stirring reaction is carried out to obtain a precursor;

[0017] C. The precursor is washed with an acid solution, centrifugally purified with ethanol, and vacuum - dried to obtain the hydrophobic acidic ZIF - 8 composite adsorbent.

[0018] Furthermore, S1 is specifically: adjusting the pH of the ceftriaxone sodium mother liquor to 2 - 5, adding 0.5 - 3 wt% activated carbon to the mother liquor, stirring for 30 - 60 min, and then filtering to remove suspended solids and organic impurities to obtain a pretreated solution.

[0019] Furthermore, the specific surface area of the hydrophobic acidic ZIF - 8 composite adsorbent is 800 - 1500 m 2 / g, the pore diameter is 0.5 - 2.5 nm, and the surface hydrophobic group coverage rate is 60 - 95%.

[0020] Furthermore, S3 is specifically: after the adsorption is completed, the hydrophobic acidic ZIF - 8 composite adsorbent is separated, and an acidic desorbing agent containing 5 - 15 wt% ethanol or acetone is used for desorbing at 40 - 80 °C for 30 - 180 min to obtain a desorbing solution, and 20 - 40 kHz ultrasonic treatment is synchronously applied during desorbing for 20 - 30 min.

[0021] Furthermore, S4 is specifically: the desorbing solution is concentrated to 20 - 50% of the original volume by a multi - effect evaporator, the vacuum degree is controlled at - 0.08 to - 0.1 MPa, the solid content at the end of concentration is 80 - 90%, and after cooling crystallization, the crude MBT is obtained.

[0022] Further, S5 specifically is: recrystallize the crude MBT with an ethanol-water mixed solvent, where the recrystallization solvent is ethanol and water with a volume ratio of 1:0.5 - 2, control the crystallization temperature at 0 - 10 °C, after centrifugal separation, dry it in a fluidized bed at 40 - 60 °C, and obtain the MBT product after drying.

[0023] Further, step B specifically is: disperse the ZIF-8 nanoparticles doped with rare earth metal oxides in ethanol, add a silane coupling agent, and the mass ratio of the silane coupling agent to ZIF-8 is 5 - 15%, stir and react at 50 - 80 °C for 4 - 12 h to obtain a precursor.

[0024] Further, step C specifically is: wash the precursor with a 0.1 - 1 M sulfuric acid or hydrochloric acid solution for 1 - 4 h, purify it by centrifugation with ethanol at 5000 - 8000 rpm, and dry it in vacuum at 60 - 100 °C to obtain a hydrophobic acidic ZIF-8 composite adsorbent.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The hydrophobic acidic ZIF-8 composite adsorbent of the present invention performs excellently in treating the cefotaxime sodium mother liquor. The regular pore structure and large specific surface area of ZIF-8 make its pore size match the size of thioether molecules, providing suitable adsorption sites for physical adsorption of thioether molecules in the pores. At the same time, the ZIF-8 framework is stable and can remain stable in a complex mother liquor environment, ensuring efficient adsorption. After acid functionalization treatment, the acidic groups on the surface of ZIF-8 form chemical bonds with thioether molecules, enhancing the adsorption effect. It also changes the surface charge distribution of ZIF-8, increasing the electrostatic attraction to thioether and making it easier to adsorb. Hydrophobic modification makes the surface of ZIF-8 hydrophobic, and the hydrophobic interaction with thioether molecules helps to preferentially adsorb thioether, improving selectivity and efficiency, and enhancing the purity of MBT. In addition, the pores of ZIF-8 can accommodate common organic solvent molecules, providing adsorption channels and storage spaces for them, enabling the solvent molecules to smoothly enter the pores for efficient physical adsorption to achieve the purpose of recovering the solvent.

[0027] 2. In the present invention, activated carbon has a developed pore structure and a large specific surface area, and can preliminarily adsorb and remove impurities in the cefotaxime sodium mother liquor. Through the pretreatment of activated carbon, some macromolecular impurities, colored substances, and part of organic substances in the mother liquor can be removed, improving the quality and composition of the mother liquor, and creating more favorable conditions for the subsequent adsorption process of the hydrophobic acidic ZIF-8 composite adsorbent;

[0028] 3. In the mother liquor after the pretreatment of activated carbon, the adsorption environment of thioether and solvent molecules is optimized, enabling the hydrophobic acidic ZIF-8 composite adsorbent to interact more effectively with target molecules, improving the adsorption rate. The activated carbon adsorbs some impurities that compete for adsorption sites with thioether or solvent, allowing more adsorption sites on the surface of ZIF-8 to be used for adsorbing thioether and solvent, thereby enhancing the adsorption efficiency. This synergistic effect can more efficiently achieve the purification and resource recovery of cefotaxime sodium mother liquor. Detailed implementation mode

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] Example 1: This example provides a process for recovering 2-mercaptobenzothiazole from cefotaxime sodium mother liquor, including the following steps:

[0031] S1: Prepare a hydrophobic acidic ZIF-8 composite adsorbent:

[0032] A. Dissolve Zn(NO3)2·6H2O and 2-methylimidazole in methanol at a molar ratio of 1:20, and perform a solvothermal reaction at 80°C for 8 h. In a closed reaction vessel, with an organic solvent as the medium, promote the coordination self-assembly of metal ions (Zn 2+ ) and organic ligands (2-methylimidazole) under high temperature and high pressure conditions to form a ZIF-8 crystal structure, and obtain ZIF-8 nanoparticles.

[0033] B. Disperse the ZIF-8 nanoparticles doped with rare earth metal oxides (the rare earth metal oxide is selected as La2O3 with a doping amount of 5% of the mass of ZIF-8 and a particle size of 10 nm, and the La2O3 nanoparticles are embedded in the ZIF-8 pores by an in-situ hydrothermal method) in ethanol, add a silane coupling agent (γ-aminopropyltriethoxysilane and γ-ureidopropyltriethoxysilane with a molar ratio of 1:1), and the mass ratio of the silane coupling agent to ZIF-8 is 15%. Stir and react at 80°C for 12 h to obtain a precursor.

[0034] C. Wash the precursor with 1M sulfuric acid solution for 4 h, purify it by centrifugation with ethanol at 8000 rpm, and dry it in vacuum at 100°C to obtain a hydrophobic acidic ZIF-8 composite adsorbent.

[0035] S2: Adjust the pH of the ceftriaxone sodium mother liquor to 5, add 3 wt% activated carbon to the mother liquor, stir for 60 min, and then filter to remove suspended solids and organic impurities to obtain a pretreated solution;

[0036] S3: Contact the pretreated solution with a hydrophobic acidic ZIF-8 composite adsorbent and adsorb at 50 °C for 120 min;

[0037] The specific surface area of the hydrophobic acidic ZIF-8 composite adsorbent is 1500 m 2 / g, the pore diameter is 2.5 nm, and the surface hydrophobic group coverage rate is 95%;

[0038] S4: After the adsorption is completed, separate the hydrophobic acidic ZIF-8 composite adsorbent, and use an acidic desorbent containing 15 wt% acetone (equivalent to the solvent described in the previous text) to desorb at 80 °C for 180 min to obtain a desorbed solution. During desorption, apply ultrasonic treatment at 40 kHz for 30 min synchronously;

[0039] S5: Concentrate the desorbed solution to 50% of the original volume using a multi-effect evaporator, control the vacuum degree at -0.1 MPa, and the solid content at the end of concentration is 90%. After cooling and crystallization, obtain the crude MBT product;

[0040] S6: Recrystallize the crude MBT product with an ethanol-water mixed solvent. The recrystallization solvent is an ethanol-water volume ratio of 1:2, control the crystallization temperature at 10 °C, after centrifugal separation, dry it in a fluidized bed at 60 °C, and obtain the MBT product after drying.

[0041] Example 2: This example provides a process for recovering 2-mercaptobenzothiazole from a ceftriaxone sodium mother liquor, including the following steps:

[0042] S1: Prepare a hydrophobic acidic ZIF-8 composite adsorbent:

[0043] A. Dissolve Zn(NO3)2·6H2O and 2-methylimidazole in methanol at a molar ratio of 1:5, and carry out a solvothermal reaction at 50 °C for 2 h. In a closed reaction vessel, using an organic solvent as the medium, promote the coordination self-assembly of metal ions (Zn 2+ ) and organic ligands (2-methylimidazole) to form a ZIF-8 crystal structure, and obtain ZIF-8 nanoparticles;

[0044] B. Disperse ZIF-8 nanoparticles doped with rare earth metal oxides (the rare earth metal oxide is CeO2 with a doping amount of 1% of the mass of ZIF-8 and a particle size of 2 nm, and CeO2 nanoparticles are embedded in the ZIF-8 pore channels by in-situ hydrothermal method) in ethanol, add a silane coupling agent (bis-(3-triethoxysilylpropyl)-tetrasulfide and γ-glycidoxypropyltrimethoxysilane with a molar ratio of 1:1), and the mass ratio of the silane coupling agent to ZIF-8 is 5%. Stir and react at 50 °C for 4 h to obtain a precursor;

[0045] C. Wash the precursor with 0.1 M hydrochloric acid solution for 1 h, purify it by centrifugation with ethanol at 5000 rpm, and dry it in vacuum at 60 °C to obtain a hydrophobic acidic ZIF-8 composite adsorbent.

[0046] S2: Adjust the pH of the ceftriaxone sodium mother liquor to 2, add 0.5 wt% activated carbon to the mother liquor, stir for 30 min, and then filter to remove suspended solids and organic impurities to obtain a pretreatment solution;

[0047] S3: Contact the pretreatment solution with the hydrophobic acidic ZIF-8 composite adsorbent and adsorb at 20 °C for 30 min;

[0048] The specific surface area of the hydrophobic acidic ZIF-8 composite adsorbent is 800 m 2 / g, the pore diameter is 0.5 nm, and the surface hydrophobic group coverage rate is 60%;

[0049] S4: After adsorption, separate the hydrophobic acidic ZIF-8 composite adsorbent, desorb with an acidic desorbent containing 5 wt% acetone at 40 °C for 30 min to obtain a desorbed solution, and apply 20 kHz ultrasonic treatment for 20 min synchronously during desorption;

[0050] S5: Concentrate the desorbed solution to 20% of the original volume using a multi-effect evaporator, control the vacuum degree at -0.08 MPa, the solid content at the end of concentration is 80%, and obtain the crude MBT after cooling crystallization;

[0051] S6: Recrystallize the crude MBT with an ethanol-water mixed solvent, the volume ratio of ethanol to water in the recrystallization solvent is 1:0.5, control the crystallization temperature at 0 °C, separate by centrifugation, and then dry in a fluidized bed at 40 °C to obtain the MBT product.

[0052] Example 3: This example provides a process for recovering 2-mercaptobenzothiazole from a ceftriaxone sodium mother liquor, including the following steps:

[0053] S1: Prepare a hydrophobic acidic ZIF-8 composite adsorbent:

[0054] A. Dissolve Zn(NO3)2·6H2O and 2-methylimidazole in methanol at a molar ratio of 1:13, and carry out a solvothermal reaction at 62 °C for 4 h. In a sealed reaction vessel, with an organic solvent as the medium, promote the coordination self-assembly of metal ions (Zn 2+ ) and the organic ligand (2-methylimidazole) under high-temperature and high-pressure conditions to form a ZIF-8 crystal structure, and obtain ZIF-8 nanoparticles;

[0055] B. Disperse the ZIF-8 nanoparticles doped with rare-earth metal oxide (the rare-earth metal oxide is selected as Nd2O3 with a doping amount of 3% of the mass of ZIF-8 and a particle size of 5 nm, and Nd2O3 nanoparticles are embedded in the ZIF-8 pore channels by an in-situ hydrothermal method) in ethanol, add a silane coupling agent (γ-aminopropyltriethoxysilane and dodecyltrimethoxysilane with a molar ratio of 1:1), and the mass ratio of the silane coupling agent to ZIF-8 is 8%. Stir and react at 67 °C for 10 h to obtain a precursor;

[0056] C. Wash the precursor with 0.5 M hydrochloric acid solution for 3 h, purify it by centrifugation with ethanol at 6000 rpm, and dry it in vacuum at 80 °C to obtain a hydrophobic acidic ZIF-8 composite adsorbent.

[0057] S2: Adjust the pH of the ceftriaxone sodium mother liquor to 3, add 2 wt% activated carbon to the mother liquor, stir for 50 min, and then filter to remove suspended solids and organic impurities to obtain a pretreated solution;

[0058] S3: Contact the pretreated solution with the hydrophobic acidic ZIF-8 composite adsorbent and adsorb at 30 °C for 50 min;

[0059] The specific surface area of the hydrophobic acidic ZIF-8 composite adsorbent is 1000 m 2 / g, the pore diameter is 1 nm, and the surface hydrophobic group coverage rate is 90%;

[0060] S4: After the adsorption is completed, separate the hydrophobic acidic ZIF-8 composite adsorbent, and desorb it with an acidic desorbent containing 10 wt% ethanol at 60 °C for 100 min to obtain a desorbed solution. Synchronously apply ultrasonic treatment at 30 kHz for 20 min during desorption;

[0061] S5: Concentrate the desorbed solution to 50% of the original volume by a multi-effect evaporator, control the vacuum degree at -0.1 MPa, and the solid content at the end of concentration is 90%. After cooling and crystallization, obtain the crude MBT product;

[0062] S6: Recrystallize the crude MBT product with an ethanol-water mixed solvent. The recrystallization solvent is an ethanol-water volume ratio of 1:1, control the crystallization temperature at 4 °C, after centrifugal separation, dry it in a fluidized bed at 45 °C, and obtain the MBT product after drying.

[0063] Comparative Example 1: The difference between this comparative example and Example 3 is that in step B, ZIF-8 is not doped with rare earth metal oxide.

[0064] This comparative example provides a process for recovering 2-mercaptobenzothiazole from cefotaxime sodium mother liquor, which includes the following steps:

[0065] S1: Preparation of hydrophobic acidic ZIF-8 composite adsorbent:

[0066] A. Dissolve Zn(NO3)2·6H2O and 2-methylimidazole in methanol at a molar ratio of 1:13, and carry out a solvothermal reaction at 62 °C for 4 h. In a closed reaction vessel, using an organic solvent as the medium, promote the coordination self-assembly of metal ions (Zn 2+ ) and organic ligands (2-methylimidazole) under high temperature and high pressure conditions to form a ZIF-8 crystal structure, and obtain ZIF-8 nanoparticles;

[0067] B. Disperse the ZIF-8 nanoparticles in ethanol, add silane coupling agents (γ-aminopropyltriethoxysilane and dodecyltrimethoxysilane with a molar ratio of 1:1), and the mass ratio of the silane coupling agent to ZIF-8 is 8%. Stir and react at 67 °C for 10 h to obtain a precursor;

[0068] C. Wash the precursor with 0.5 M hydrochloric acid solution for 3 h, purify it by centrifugation with ethanol at 6000 rpm, and dry it in vacuum at 80 °C to obtain a hydrophobic acidic ZIF-8 composite adsorbent.

[0069] S2: Adjust the pH of the cefotaxime sodium mother liquor to 3, add 2 wt% activated carbon to the mother liquor, stir for 50 min, and then filter to remove suspended solids and organic impurities to obtain a pretreated solution;

[0070] S3: Contact the pretreated solution with the hydrophobic acidic ZIF-8 composite adsorbent and adsorb at 30 °C for 50 min;

[0071] The specific surface area of the hydrophobic acidic ZIF-8 composite adsorbent is 1000 m 2 / g, the pore diameter is 1 nm, and the surface hydrophobic group coverage rate is 90%;

[0072] S4: After the adsorption is completed, separate the hydrophobic acidic ZIF-8 composite adsorbent, and desorb it with an acidic desorbent containing 10 wt% ethanol at 60 °C for 100 min to obtain a desorbed solution. Synchronously apply ultrasonic treatment at 30 kHz for 20 min during desorption;

[0073] S5: Concentrate the desorbed solution to 50% of the original volume using a multi-effect evaporator, control the vacuum degree at -0.1 MPa, and the solid content at the end of concentration is 90%. After cooling and crystallization, obtain the crude MBT;

[0074] S6: Recrystallize the crude MBT with an ethanol-water mixed solvent. The recrystallization solvent is ethanol and water with a volume ratio of 1:1. Control the crystallization temperature at 4°C. After centrifugal separation, dry it in a fluidized bed at 45°C to obtain the MBT product.

[0075] Comparative Example 2: The difference between this comparative example and Example 3 is that 2 wt% activated carbon was not added to the mother liquor. After stirring for 50 min, filter to remove suspended solids and organic impurities.

[0076] This comparative example provides a recovery process for 2-mercaptobenzothiazole in a cefotaxime sodium mother liquor, including the following steps:

[0077] S1: Prepare a hydrophobic acidic ZIF-8 composite adsorbent:

[0078] A. Dissolve Zn(NO3)2·6H2O and 2-methylimidazole in methanol at a molar ratio of 1:13, and carry out a solvothermal reaction at 62°C for 4 h. In a sealed reaction vessel, using an organic solvent as the medium, promote the coordination self-assembly of metal ions (Zn 2+ ) and organic ligands (2-methylimidazole) under high temperature and high pressure conditions to form a ZIF-8 crystal structure and obtain ZIF-8 nanoparticles;

[0079] B. Disperse the ZIF-8 nanoparticles doped with rare earth metal oxides (the rare earth metal oxide is selected as Nd2O3 with a doping amount of 3% of the mass of ZIF-8 and a particle size of 5 nm. Nd2O3 nanoparticles are embedded in the ZIF-8 pores by an in-situ hydrothermal method) in ethanol, add a silane coupling agent (γ-aminopropyltriethoxysilane and dodecyltrimethoxysilane with a molar ratio of 1:1), and the mass ratio of the silane coupling agent to ZIF-8 is 8%. Stir and react at 67°C for 10 h to obtain a precursor;

[0080] C. Wash the precursor with 0.5 M hydrochloric acid solution for 3 h, purify it by centrifugation with ethanol at 6000 rpm, and dry it in vacuum at 80°C to obtain a hydrophobic acidic ZIF-8 composite adsorbent.

[0081] S2: Adjust the pH of the cefotaxime sodium mother liquor to 3 to obtain a pretreatment solution;

[0082] S3: Contact the pretreatment solution with the hydrophobic acidic ZIF-8 composite adsorbent and adsorb at 30°C for 50 min;

[0083] The specific surface area of the hydrophobic acidic ZIF-8 composite adsorbent is 1000 m 2 / g, the pore diameter is 1 nm, and the surface hydrophobic group coverage rate is 90%;

[0084] S4: After the adsorption is completed, the hydrophobic acidic ZIF-8 composite adsorbent is separated, and desorbed with an acidic desorbent containing 10 wt% ethanol at 60 °C for 100 min to obtain a desorbed solution. During desorption, ultrasonic treatment at 30 kHz is applied synchronously for 20 min;

[0085] S5: The desorbed solution is concentrated to 50% of the original volume by a multiple-effect evaporator, the vacuum degree is controlled at -0.1 MPa, the solid content at the end of concentration is 90%, and the crude MBT is obtained after cooling crystallization;

[0086] S6: The crude MBT is recrystallized with an ethanol-water mixed solvent, the recrystallization solvent is ethanol and water with a volume ratio of 1:1, the crystallization temperature is controlled at 4 °C, centrifuged and separated, and then dried in a fluidized bed at 45 °C to obtain the MBT product.

[0087] Comparative Example 3: The difference between this comparative example and Example 3 is that neither 2 wt% activated carbon was added to the mother liquor, stirred for 50 min and then filtered to remove suspended solids and organic impurities, nor was rare earth metal oxide doped in ZIF-8.

[0088] This example provides a recovery process for 2-mercaptobenzothiazole in cefotaxime sodium mother liquor, including the following steps:

[0089] S1: Preparation of hydrophobic acidic ZIF-8 composite adsorbent:

[0090] A. Zn(NO3)2·6H2O and 2-methylimidazole are dissolved in methanol according to a molar ratio of 1:13, and solvothermal reaction is carried out at 62 °C for 4 h. In a closed reaction vessel, with an organic solvent as the medium, metal ions (Zn 2+ ) and organic ligands (2-methylimidazole) undergo coordination self-assembly to form a ZIF-8 crystal structure, and ZIF-8 nanoparticles are prepared;

[0091] B. The ZIF-8 nanoparticles are dispersed in ethanol, and a silane coupling agent (γ-aminopropyltriethoxysilane and dodecyltrimethoxysilane with a molar ratio of 1:1) is added. The mass ratio of the silane coupling agent to ZIF-8 is 8%, and stirring reaction is carried out at 67 °C for 10 h to obtain a precursor;

[0092] C. The precursor is washed with 0.5 M hydrochloric acid solution for 3 h, centrifugally purified with ethanol at 6000 rpm, and vacuum dried at 80 °C to obtain the hydrophobic acidic ZIF-8 composite adsorbent.

[0093] S2: Adjust the pH of the cefotaxime sodium mother liquor to 3 to obtain a pretreated solution;

[0094] S3: Contact the pretreated solution with the hydrophobic acidic ZIF-8 composite adsorbent and adsorb at 30 °C for 50 min;

[0095] The specific surface area of the hydrophobic acidic ZIF-8 composite adsorbent is 1000 m 2 / g, the pore diameter is 1 nm, and the surface hydrophobic group coverage rate is 90%;

[0096] S4: After the adsorption is completed, the hydrophobic acidic ZIF-8 composite adsorbent is separated, and desorbed with an acidic desorbent containing 10 wt% ethanol at 60 °C for 100 min to obtain a desorbed solution. During desorption, ultrasonic treatment at 30 kHz is applied synchronously for 20 min;

[0097] S5: The desorbed solution is concentrated to 50% of the original volume by a multi-effect evaporator, the vacuum degree is controlled at -0.1 MPa, the solid content at the end of concentration is 90%, and the crude MBT is obtained after cooling crystallization;

[0098] S6: The crude MBT is recrystallized with an ethanol-water mixed solvent, the recrystallization solvent is ethanol and water with a volume ratio of 1:1, the crystallization temperature is controlled at 4 °C, centrifuged and separated, and then dried in a fluidized bed at 45 °C to obtain the MBT product.

[0099] Control example: This control example provides a recovery process for 2-mercaptobenzothiazole in the cefotaxime sodium mother liquor (Chinese invention patent CN102351809B), including the following steps:

[0100] Step 1: In a 2000 mL round-bottom flask, add 1600 mL of the cefotaxime sodium mother liquor, and adjust the pH = 3.0 with a sulfuric acid solution with a mass concentration of 85%;

[0101] Step 2: Heat and distill the mother liquor obtained in Step 1 to distill out 1280 mL of the solvent, and reserve the residual solution after distillation;

[0102] Step 3: Cool the residual solution obtained in Step 2 to 5 °C, and a small amount of solid will precipitate. Filter to remove the solid, and reserve the filtrate;

[0103] Step 4: Add water with a volume three times that of the filtrate to the filtrate obtained in Step 3 and stir, and a large amount of solid will precipitate;

[0104] Step 5: Filter out the solid obtained in Step 4, wash it with water and dry it to obtain the target product 2-mercaptobenzothiazole, weigh 12.6 g, and the recovery rate is 97.8%; sample and detect by high performance liquid chromatography, and the content is 98.41%.

[0105] Experimental example: The purity and recovery rate of the MBT products prepared in Examples 1-3 and Comparative Examples 1-3 were detected;

[0106] Detection was carried out according to the HPLC method in GB / T11407—2013, and the steps are as follows:

[0107] Weigh about 0.5 g of the sample, accurate to 0.1 mg, dissolve it with acetonitrile, and use acetic acid solution (0.001 mol / L)∶acetonitrile (containing 0.001 mol / L acetic acid) = 65∶35 as the mobile phase;

[0108] Use a stainless steel column filled with SB-C18 and an ultraviolet detector (325 nm) to perform reverse-phase high-performance liquid chromatography separation and determination of MBT in the sample, and the external standard method is used for the calculation method.

[0109] Detector: Multi-wavelength ultraviolet spectrophotometric detector or a spectrophotometric detector with equivalent performance.

[0110] Chromatographic column: A stainless steel column with an inner diameter of 4.6 mm and a length of 250 mm, filled with 5 μm SB-C18 packing;

[0111] Microsyringe: 50 μL flat head;

[0112] Reagents: Acetonitrile, glacial acetic acid, water (filtered through a 0.45 μm filter membrane);

[0113] MBT standard sample: The mass fraction of MBT is known to be ≥ 99.5%. The standard sample can be prepared by repeatedly recrystallizing and purifying MBT with an appropriate solvent. The evaluation of the purity of the standard substance is determined by impurity HPLC gradient analysis and differential thermal analysis (DTA). The standard substance is stored below 5 °C, and the impurity HPLC analysis is performed every three months;

[0114] The recovery rate is calculated according to the following formula:

[0115] Recovery rate (%) = (actually measured MBT amount / theoretical MBT amount) × 100%

[0116] The purity of MBT is expressed as the mass fraction w2, and the value is expressed in %, and is calculated according to the following formula

[0117] w2 = (A2m2p / A1m3) × 100%

[0118] In the formula:

[0119] A2 ——— The value of the MBT peak area in the sample solution;

[0120] m2 ——— The value of the mass of the standard sample, in grams (g);

[0121] p ——— The value of the mass fraction of MBT in the standard sample, %;

[0122] A1 ——— The value of the MBT peak area in the standard sample solution;

[0123] m3 ——— The value of the mass of the sample, in grams (g).

[0124] Calculation formula for the removal rate of thioether:

[0125] Removal rate = (C O - C e ) / C O × 100%

[0126] In the formula:

[0127] C0: Initial concentration of thioether in the solution before adsorption (mg / L);

[0128] C e : Residual concentration of thioether in the solution after adsorption equilibrium (mg / L).

[0129] Calculation formula for the recovery rate of the solvent:

[0130] Recovery rate = (Actual amount of recovered solvent / Total initial amount of solvent) × 100%

[0131] In the formula:

[0132] Actual amount of recovered solvent: Amount of solvent adsorbed by the hydrophobic acidic ZIF-8 composite adsorbent (unit: kg) or amount of solvent distilled out by heating (unit: kg);

[0133] Total initial amount of solvent: Total amount of solvent used in the MBT recovery process (unit: kg).

[0134] Detailed data are shown in the following table:

[0135]

[0136] Data analysis: As a typical metal-organic framework material, ZIF-8 has a regular pore structure and a large specific surface area. The pore size is matched with the size of thioether molecules, which can provide suitable adsorption sites for thioether molecules, enabling physical adsorption of thioether molecules in the pores. At the same time, the framework structure of ZIF-8 is stable, which can maintain the stability of its morphology and performance in a complex mother liquor environment, ensuring the efficient progress of the adsorption process;

[0137] In the present invention, ZIF-8 is subjected to acidic functionalization treatment to introduce acidic groups on its surface. These acidic groups can chemically adsorb thioether molecules, further enhancing the adsorption effect by forming chemical bonds. In addition, the presence of acidic groups can change the charge distribution on the surface of ZIF-8, increasing the electrostatic attraction to thioether molecules, making thioether molecules more likely to approach and adsorb on the surface of ZIF-8;

[0138] The surface of ZIF-8 is made hydrophobic through hydrophobic modification. The thioether molecule itself has a certain degree of hydrophobicity. In the cefotaxime sodium mother liquor, a hydrophobic interaction can form between the hydrophobic ZIF-8 and the thioether molecule. This interaction helps to preferentially adsorb the thioether molecule in the complex mother liquor system, improving the selectivity and efficiency of adsorption, and thus more effectively increasing the purity of MBT.

[0139] The pore size and shape of ZIF-8 can be adapted to common organic solvent molecules (such as methanol, ethanol, acetone, etc.), providing good adsorption channels and storage spaces for the solvent molecules. During the mother liquor treatment process, the solvent molecules can smoothly enter the pores of ZIF-8 to achieve efficient physical adsorption, thereby achieving the purpose of recovering the solvent.

[0140] Activated carbon has a developed pore structure and a large specific surface area, and can preliminarily adsorb and remove impurities in the cefotaxime sodium mother liquor. Through the pretreatment with activated carbon, some macromolecular impurities, colored substances, and part of the organic substances in the mother liquor can be removed, improving the quality and composition of the mother liquor, and creating more favorable conditions for the adsorption process of the subsequent hydrophobic acidic ZIF-8 composite adsorbent.

[0141] In the mother liquor pretreated with activated carbon, the adsorption environment of the thioether and solvent molecules is optimized, enabling the hydrophobic acidic ZIF-8 composite adsorbent to interact more effectively with the target molecules, increasing the adsorption rate. The activated carbon adsorbs some impurities that compete with the thioether or solvent for adsorption sites, making the adsorption sites on the surface of ZIF-8 more available for adsorbing the thioether and solvent, thereby improving the adsorption efficiency.

[0142] In summary, the hydrophobic acidic ZIF-8 composite adsorbent of the present invention has important application value in the field of cefotaxime sodium mother liquor treatment. It can not only increase the purity of MBT, but also achieve efficient recovery of the solvent, reduce production costs, and reduce environmental pollution, having significant technical advantages and practical benefits.

[0143] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A recovery process of 2-mercaptobenzothiazole in cefotaxime sodium mother liquor, characterized in that, It includes the following steps: S1: Adjust the pH of the ceftriaxone sodium mother liquor, add activated carbon to the mother liquor, stir and then filter to remove suspended solids and organic impurities to obtain a pretreatment solution; S2: Contact the pretreatment solution with a hydrophobic acidic ZIF-8 composite adsorbent and adsorb for 30 - 120 min at 20 - 50 °C; S3: After adsorption, separate the hydrophobic acidic ZIF-8 composite adsorbent, desorb with an acidic desorbent for 30 - 180 min to obtain a desorbed solution, and apply ultrasonic waves synchronously during desorption; S4: Concentrate the desorbed solution to 20 - 50% of the original volume using a multi-effect evaporator, cool and crystallize to obtain crude MBT; S5: Recrystallize the crude MBT with an ethanol-water mixed solvent, control the crystallization temperature at 0 - 10 °C, centrifuge and separate, and then dry to obtain the MBT product; The preparation method of the hydrophobic acidic ZIF-8 composite adsorbent includes the following steps: A. Dissolve Zn(NO3)2·6H2O and 2-methylimidazole in methanol at a molar ratio of 1:5 - 20, and carry out a solvothermal reaction at 50 - 80 °C to obtain ZIF-8 nanoparticles; B. Disperse the ZIF-8 nanoparticles doped with rare earth metal oxides in ethanol, add a silane coupling agent, and stir and react to obtain a precursor; C. Wash the precursor with an acid solution, purify by centrifugation with ethanol, and dry in vacuum to obtain the hydrophobic acidic ZIF-8 composite adsorbent.

2. The process according to claim 1, characterized in that, Specifically, S1 is: Adjust the pH of the ceftriaxone sodium mother liquor to 2 - 5, add 0.5 - 3 wt% activated carbon to the mother liquor, stir for 30 - 60 min, and then filter to remove suspended solids and organic impurities to obtain a pretreatment solution.

3. The process according to claim 1, characterized in that, The specific surface area of the hydrophobic acidic ZIF-8 composite adsorbent is 800 - 1500 m 2 / g, the pore size is 0.5 - 2.5 nm, and the surface hydrophobic group coverage rate is 60 - 95%.

4. The process according to claim 1, characterized in that, Specifically, S3 is: After adsorption, separate the hydrophobic acidic ZIF-8 composite adsorbent, desorb with an acidic desorbent containing 5 - 15 wt% ethanol or acetone at 40 - 80 °C for 30 - 180 min to obtain a desorbed solution, and apply ultrasonic treatment at 20 - 40 kHz for 20 - 30 min synchronously during desorption.

5. The process according to claim 1, characterized in that, Specifically, S4 is: Concentrate the desorbed solution to 20 - 50% of the original volume using a multi-effect evaporator, control the vacuum degree at -0.08 to -0.1 MPa, and the solid content at the end of concentration is 80 - 90%, cool and crystallize to obtain crude MBT.

6. The process according to claim 1, characterized in that, Specifically, S5 is: Recrystallize the crude MBT with an ethanol-water mixed solvent, the recrystallization solvent is ethanol and water with a volume ratio of 1:0.5 - 2, control the crystallization temperature at 0 - 10 °C, centrifuge and separate, and then dry in a fluidized bed at 40 - 60 °C to obtain the MBT product.

7. The process according to claim 1, characterized in that, Specifically, step B is: Disperse the ZIF-8 nanoparticles doped with rare earth metal oxides in ethanol, add a silane coupling agent, the mass ratio of the silane coupling agent to ZIF-8 is 5 - 15%, and stir and react at 50 - 80 °C for 4 - 12 h to obtain a precursor.

8. The process according to claim 1, characterized in that, Specifically, step C is: Wash the precursor with a 0.1 - 1 M sulfuric acid or hydrochloric acid solution for 1 - 4 h, purify by centrifugation with ethanol at 5000 - 8000 rpm, and dry in vacuum at 60 - 100 °C to obtain the hydrophobic acidic ZIF-8 composite adsorbent.

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