Sebacic acid extraction method

Abstract

The invention discloses an extraction method of sebacic acid. The method comprises the following steps: firstly, adjusting sebacic acid fermentation liquor produced by a microbial fermentation method, and accurately controlling the temperature, viscosity and pH value to obtain first mixed liquor; heating and preserving heat to obtain a second mixed solution, and performing membrane filtration; and after the filtrate is subjected to acidification crystallization and solid-liquid separation, solid matters are washed and refined, and secondary treatment can also be carried out. Compared with the prior art, the method is more accurate in parameter control of each step, and key steps such as decoloration pretreatment are added. The prepared sebacic acid product is higher in purity, the content of sebacic acid is larger than or equal to 99.9%, the content of impurities such as water, ash, iron ions and nitrogen is lower, and the color / light transmittance is better. The method can reduce the consumption of acid and alkali and the content of inorganic salt in water, reduces the sewage treatment load, is simple and convenient to operate, is suitable for large-scale industrial production, and has important significance for improving the quality and production benefits of sebacic acid products.

Description

Technical Field

[0001] The present invention relates to the technical field of sebacic acid extraction, in particular to a method for extracting sebacic acid. Background Art

[0002] Sebacic acid, an important fine chemical product, is widely used in numerous industrial fields. Currently, microbial fermentation for its production has attracted attention due to its advantages, including a wide range of raw material sources, simple process, and mild conditions. However, the fermentation broth is complex, consisting of multiple phases, including aqueous, oily, and solid components, and the presence of emulsification between the aqueous and oily phases makes the extraction and purification of sebacic acid difficult.

[0003] Existing extraction methods, such as the method disclosed in Chinese invention patent CN101121653B, can realize the extraction of sebacic acid, but there are many problems. The method needs to add excessive alkali to the fermentation liquid to make the pH to 7-11 to separate impurities such as bacterial cells, and then add acid to adjust the pH to 2-5 for acidification and crystallization, which not only causes the acid-base input amount to be large, increases production cost, and acid-base salification can increase the manpower and material cost of post-processing process, the desalination process complexity is high, and improper treatment can also cause adverse effects on the environment. Therefore, it is of great significance to develop a kind of extraction method that can reduce acid-base consumption, reduce inorganic salt content in water, alleviate sewage treatment load and improve sebacic acid product quality.

[0004] Based on this, a method for extracting sebacic acid is proposed. Summary of the Invention

[0005] The object of the present invention is to provide a method for extracting sebacic acid in order to solve the above-mentioned problems.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A method for extracting sebacic acid specifically comprises the following steps: Regulating the fermentation liquid: Use acid or alkali to regulate the fermentation liquid obtained in the process of producing sebacic acid by microbial fermentation, and heat the fermentation liquid at the same time, control the temperature at 62-64°C, and adjust the viscosity of the fermentation liquid to 130-170 centipoise at this temperature to obtain a first mixed liquid. During the adjustment process, the optional alkalis include sodium hydroxide, potassium hydroxide, ammonia water, etc., and the acids include sulfuric acid, hydrochloric acid, acetic acid, etc. In this step, the pH value of the first mixed liquid is controlled at 5.4-5.6, for example, 5.45, 5.5, and 5.55. The concentration of sebacic acid in the fermentation liquid is controlled at 8-12wt%, and the sebacic acid concentration of the fermentation liquid can be adjusted by dilution or concentration.

[0007] Heating and heat preservation: Heat the first mixed solution to raise its temperature to 92-94° C., at which time the viscosity of the mixed solution is 35-45 centipoise, and keep it warm for 40-60 minutes to obtain a second mixed solution.

[0008] Filtration: The second mixed liquid is filtered using membrane filtration to remove impurities such as bacteria and large proteins. The filtration membrane is a ceramic membrane, the operating pressure is controlled at 0.3-0.5 MPa, the pore size of the membrane core is 0.08-0.12 microns, and the membrane filtration temperature is 70-80°C.

[0009] Acidification and Crystallization: The filtered filtrate is subjected to acidification and crystallization. Activated carbon is first added to the filtrate for decolorization. The amount of activated carbon added is 3-5wt% of the sebacic acid content in the filtrate. The decolorization temperature is controlled at 70-80°C for 30-60 minutes. After decolorization, the decolorizer is separated by plate and frame filtration. The pH of the filtrate is then adjusted to 2.5-3.5. Acids such as sulfuric acid and hydrochloric acid can be used. After pH adjustment, the solution is heated to 93-97°C, held at this temperature for 40-60 minutes, and then cooled to 32-38°C to precipitate sebacic acid crystals and achieve recrystallization.

[0010] Solid-liquid separation and washing: The solid-liquid mixture after acidification and crystallization is separated using plate and frame filtration or centrifugal filtration to obtain a solid containing sebacic acid. The solid is washed with deionized water to remove impurities remaining on the surface.

[0011] Refining: The washed solids are mixed with an organic solvent at 80-90°C, with a mass ratio of 1:2.3-2.4. The organic solvents used are acetic acid or methyl acetate, with a purity of ≥98%. After mixing, the mixture is decolorized using activated carbon at a dosage of 2-4% by weight of the sebacic acid contained in the first-stage sebacic acid product solution. The decolorization temperature is 70-80°C, and the decolorization time is 30-60 minutes. After decolorization, the decolorizer is separated by centrifugation. The decolorized mixture is then crystallized, with the endpoint temperature for crystallization being 22-28°C. Finally, the second solid-liquid mixture undergoes solid-liquid separation using plate and frame filtration or vacuum filtration. The separated solids are then washed and dried to yield the sebacic acid product.

[0012] Secondary treatment: The sebacic acid product obtained after the refined treatment is placed in water at 95-105°C (with a mass fraction of sebacic acid in the water of 20-30 wt%) for 30-90 minutes. After the temperature is reduced to 30-50°C, solid-liquid separation is performed using centrifugal filtration or plate and frame filtration. The sebacic acid after solid-liquid separation is washed with water and then dried using paddle drying or airflow drying to further improve the purity of the sebacic acid product.

[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The sebacic acid extraction method of the present invention has significant advantages. In the fermentation liquid adjustment step, the temperature and viscosity are precisely controlled, and only a small amount of acid or alkali is used to convert the sebacic acid precipitated in the fermentation liquid into salts that dissolve in the fermentation liquid. This reduces the amount of dilution water while avoiding the secondary precipitation of sebacic acid salts, reduces the consumption of acid during subsequent acidification and crystallization, reduces the content of inorganic salts in wastewater, and alleviates the sewage treatment load. Specific membrane filtration conditions are used to more effectively remove impurities and improve product purity. During the refining process, the optimized parameter settings further improve product quality. The sebacic acid product obtained by this method has high purity, sebacic acid content ≥99.9%, moisture content <0.15%, ash content <15ppm, iron ion content <2ppm, nitrogen content <25ppm, color / transmittance 440nm / 550nm>97 / 99, which is superior to the sebacic acid product produced by the prior art, can better meet the requirements of high-end polymer products for monomer raw materials, and is conducive to improving the quality of downstream high-end products. Moreover, the method is simple and easy to operate and is suitable for large-scale industrial production. DETAILED DESCRIPTION

[0014] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0015] The present invention provides a technical solution: Example 1

[0016] Fermentation broth preparation: Candida visenbergii was used to produce sebacic acid. During the fermentation process, the pH of the fermentation system was maintained at 4.0-6.0 during the growth phase and 5.0-6.0 during the conversion phase. The fermentation temperature was 30°C, the ventilation rate was 0.5 vvm, and the pressure was 0.1 MPa. After fermentation, a fermentation broth with a sebacic acid concentration of 10 wt% and a viscosity of 450 centipoise was obtained.

[0017] Extraction process Adjusting the fermentation broth: adjusting the fermentation broth with sulfuric acid and sodium hydroxide, heating it to 63° C., and adjusting the viscosity of the fermentation broth to 150 centipoise and the pH to 5.5 to obtain a first mixed solution.

[0018] Heating and heat preservation: The first mixed solution was heated to 93° C., the viscosity became 40 centipoise, and the mixture was kept warm for 50 minutes to obtain a second mixed solution.

[0019] Filtration: The second mixed solution was filtered through a ceramic membrane with a 0.1 μm pore size, an operating pressure of 0.4 MPa, and a filtration temperature of 75°C to remove impurities such as bacteria. Activated carbon containing 4% by weight of the sebacic acid content in the filtrate was added to the filtered solution for decolorization. The decolorization temperature was 75°C for 40 minutes, and the decolorizing agent was separated by plate and frame filtration.

[0020] Acidification crystallization: Use sulfuric acid to adjust the pH value of the filtrate to 3.0, raise the temperature to 95℃, keep warm for 50 minutes, and then cool to 35℃ to precipitate sebacic acid crystals.

[0021] Solid-liquid separation and washing: Use plate and frame filtration to separate the solid-liquid mixture to obtain solids, and wash the solids with deionized water.

[0022] Refining: The solids were mixed with acetic acid (98% purity) in a mass ratio of 1:2.3 and mixed thoroughly at 85°C. Activated carbon (3% by weight of the solids) was added for decolorization at 75°C for 40 minutes. The decolorizer was removed by centrifugation. The decolorized mixture was cooled to 25°C for crystallization, followed by solid-liquid separation using vacuum filtration. The resulting solid was washed with water and dried to obtain the sebacic acid product.

[0023] Example 2

[0024] Fermentation broth preparation: Sebacic acid was produced using Candida tropicalis. The pH of the fermentation system was maintained at 3.5-5.5 during the growth phase and 4.5-5.5 during the conversion phase. The fermentation temperature was 29°C, the ventilation rate was 0.4 vvm, and the pressure was 0.09 MPa. After fermentation, a fermentation broth with a sebacic acid concentration of 9 wt% and a viscosity of 420 centipoise was obtained.

[0025] Extraction process Adjusting the fermentation liquid: adjusting the fermentation liquid with sulfuric acid and ammonia water, heating it to 62° C., and adjusting the viscosity of the fermentation liquid to 140 centipoise and the pH value to 5.45 to obtain a first mixed liquid.

[0026] Heating and heat preservation: The first mixed solution was heated to 92° C., the viscosity became 38 centipoise, and the mixture was kept warm for 45 minutes to obtain a second mixed solution.

[0027] Filtration: Ceramic membrane filtration was performed with a core pore size of 0.09 μm, an operating pressure of 0.35 MPa, and a membrane filtration temperature of 72°C. Activated carbon containing 3.5 wt% of the sebacic acid content in the filtrate was added to the filtered solution for decolorization. The decolorization temperature was 72°C and the decolorization time was 35 minutes. The decolorizer was then separated by plate and frame filtration.

[0028] Acidification crystallization: Adjust the pH value of the filtrate to 2.8 with hydrochloric acid, raise the temperature to 94°C, keep warm for 45 minutes, and then cool to 33°C to precipitate sebacic acid crystals.

[0029] Solid-liquid separation and washing: Solid-liquid separation is performed by centrifugal filtration, and the solids are washed with deionized water.

[0030] Refining: The solids were mixed with methyl acetate (98% purity) in a mass ratio of 1:2.35 at 82°C. Activated carbon (2.5% by weight of the solids) was added for decolorization at 72°C for 35 minutes. The decolorizer was removed by centrifugation. The mixture was cooled to 23°C for crystallization. The solid-liquid separation was performed using plate and frame filtration. The resulting solid was washed with water and dried to obtain the sebacic acid product.

[0031] Example 3

[0032] Fermentation broth preparation: Candida sakei was used as the fermentation strain to produce sebacic acid. The pH of the fermentation system was controlled at 4.5-6.5 during the growth phase and 5.5-6.5 during the conversion phase. The fermentation temperature was 31°C, the ventilation rate was 0.6 vvm, and the pressure was 0.11 MPa. After fermentation, the fermentation broth had a sebacic acid concentration of 11 wt% and a viscosity of 480 centipoise.

[0033] Extraction process Adjusting the fermentation broth: adjusting the fermentation broth with hydrochloric acid and sodium hydroxide, heating to 64° C., and adjusting the fermentation broth to a viscosity of 160 centipoise and a pH of 5.55 to obtain a first mixed solution.

[0034] Heating and heat preservation: The first mixed solution was heated to 94° C., the viscosity became 42 centipoise, and the mixture was kept warm for 55 minutes to obtain a second mixed solution.

[0035] Filtration: Ceramic membrane filtration was performed with a core pore size of 0.11 μm, an operating pressure of 0.45 MPa, and a membrane filtration temperature of 78°C. Activated carbon containing 4.5 wt% of the sebacic acid content in the filtrate was added to the filtered solution for decolorization. The decolorization temperature was 78°C for 50 minutes, and the decolorizer was separated by plate and frame filtration.

[0036] Acidification crystallization: Adjust the pH value of the filtrate to 3.2 with sulfuric acid, raise the temperature to 96°C, keep warm for 55 minutes, and then cool to 36°C to precipitate sebacic acid crystals.

[0037] Solid-liquid separation and washing: Use plate and frame filtration to separate solids and liquids, and use deionized water to wash the solids.

[0038] Refining: The solids were mixed with acetic acid (99% purity) in a mass ratio of 1:2.4 at 88°C. Activated carbon (3.5% by weight of the solids) was added for decolorization at 78°C for 50 minutes. The decolorizer was removed by centrifugation. The mixture was cooled to 27°C for crystallization. Vacuum filtration was used for solid-liquid separation. The resulting solid was washed with water and dried to obtain the sebacic acid product.

[0039] Comparative Example 1 Preparation of fermentation broth: same as the fermentation broth in Example 1.

[0040] Extraction process: Extraction was performed according to the method disclosed in Chinese invention patent CN101121653B. The fermentation broth was adjusted to a pH of 9 by adding alkali, heated to 80°C, and the bacterial cells were separated by centrifugation to obtain a dicarboxylic acid supernatant. Activated carbon was added to the supernatant at a concentration of 3% by volume, and decolorized at 70°C for 60 minutes. The activated carbon was then removed by filtration. The decolorized solution was then heated to 80°C, and the pH was adjusted to 3 with acid for acidification and crystallization. The acidified crystals were filtered through a plate and frame filter to obtain the crude long-chain dicarboxylic acid. The crude product was dissolved in an organic solvent, and activated carbon was added at a concentration of 3% by volume of the total solution. The solution was heated to 80°C for decolorization for 60 minutes, filtered while hot, and the supernatant was cooled to 20°C to allow the sebacic acid to crystallize. The product was collected by centrifugation, washed multiple times with distilled water, and dried to obtain the sebacic acid product.

[0041] Comparative Example 2 Preparation of fermentation broth: same as the fermentation broth in Example 2.

[0042] Extraction Process: During the fermentation broth conditioning step, the temperature and viscosity of the fermentation broth were not controlled, and subsequent operations proceeded directly. The pH of the fermentation broth was adjusted to 5.45 using sulfuric acid and aqueous ammonia. The broth was not heated to a specific temperature, and no attention was paid to changes in viscosity. The parameters for subsequent filtration, acidification and crystallization, solid-liquid separation, and refining steps were the same as in Example 2.

[0043] Comparative Example 3 Preparation of fermentation broth: same as the fermentation broth in Example 3.

[0044] Extraction process: In the purification step, the mass ratio of solids to organic solvent was 1:2, and the purity of the organic solvent was 90%. Other step parameters were the same as those in Example 3.

[0045] Performance test: The sebacic acid products obtained in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The test items and methods are as follows: Sebacic acid content (purity): The sample to be tested is subjected to conventional gas chromatography pretreatment and gas chromatography detection. The sebacic acid content is calculated based on the sebacic acid peak area.

[0046] Moisture content: The ratio of volatile matter lost in the sample to the total weight when the sample is heated to constant weight at 105°C using the loss on drying method.

[0047] Ash content: Burn the sample to be tested in a crucible, then burn it in a muffle furnace at 700-800℃ for 2 hours. After cooling to constant weight, measure the weight and calculate the percentage of the sample weight.

[0048] Iron ion content: The iron salt content (ppm) in the sample was determined using the o-phenanthroline method.

[0049] Nitrogen content: measured by Kjeldahl method.

[0050] Color / transmittance: Take a 25% dimethyl sulfoxide solution of the sample to be tested and use a spectrophotometer to measure its transmittance at 440nm and 550nm.

[0051] Test results: The test results are shown in the following table: Sample number Sebacic acid content (%) Moisture content (%) Ash content (ppm) Iron ion content (ppm) Nitrogen content (ppm) Color / transmittance (440nm / 550nm) Example 1 99.92 0.12 12 1.8 22 97.5 / 99.2 Example 2 99.91 0.13 13 1.9 23 97.3 / 99.1 Example 3 99.93 0.11 11 1.7 21 97.7 / 99.3 Comparative Example 1 99.5 0.18 18 2.5 28 95.5 / 98.2 Comparative Example 2 99.7 0.16 16 2.2 25 96.2 / 98.6 Comparative Example 3 99.8 0.14 15 2.0 24 96.8 / 98.8 The test results show that the sebacic acid products prepared in Examples 1-3 outperformed the products in Comparative Examples 1-3 in all indicators. The example products had higher sebacic acid content, lower moisture, ash, iron ion, and nitrogen contents, and better color and transmittance, fully demonstrating the superiority of the extraction method of the present invention.

[0052] The above description of the embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for extracting sebacic acid, characterized in that: The method comprises the following steps: Step 1: Using an acid or base to adjust the fermentation broth obtained during the production of sebacic acid by microbial fermentation, while heating the fermentation broth, controlling the temperature at 62-64° C., and adjusting the viscosity of the fermentation broth to 130-170 centipoise at this temperature, to obtain a first mixed solution with a pH of 5.4-5.6, and the concentration of sebacic acid in the fermentation broth is 8-12 wt %; Step 2: heating the first mixed solution to 92-94° C., at which point the viscosity of the mixed solution is 35-45 centipoise, and maintaining the temperature for 40-60 minutes to obtain a second mixed solution; Step 3: Filtering the second mixed liquid by membrane filtration, wherein the filtration membrane is a ceramic membrane, the operating pressure is controlled at 0.3-0.5 MPa, the pore size of the filtration membrane core is 0.08-0.12 μm, and the membrane filtration temperature is 70-80° C.; Step 4: The filtered filtrate is subjected to an acidification crystallization treatment. Activated carbon is first added to the filtrate for decolorization. The amount of activated carbon added is 3-5 wt% of the sebacic acid content in the filtrate. The decolorization temperature is controlled at 70-80°C for 30-60 minutes. After decolorization, the decolorizer is separated by plate and frame filtration. The pH value of the filtrate is then adjusted to 2.5-3.

5. After the pH value is adjusted, the solution is heated to 93-97°C, kept warm for 40-60 minutes, and then cooled to 32-38°C to precipitate sebacic acid crystals. Step 5: performing solid-liquid separation on the solid-liquid mixture after acidification and crystallization by plate and frame filtration or centrifugal filtration to obtain a solid containing sebacic acid, and washing the solid with deionized water; Step 6: mixing the washed solid with an organic solvent at a temperature of 80-90°C, with a mass ratio of solid to organic solvent of 1:(2.3-2.4), wherein the organic solvent is selected from one or more of acetic acid and methyl acetate, with a purity of ≥98%; after mixing, decolorizing treatment is performed, and activated carbon is selected as a decolorizing agent, and the amount of activated carbon is 2-4wt% of the weight of sebacic acid contained in the first-stage sebacic acid product solution. The decolorizing temperature is 70-80°C, the decolorizing time is 30-60 minutes, and after decolorization, the decolorizing agent is separated by centrifugal filtration; then, the decolorized mixture is crystallized, and the end point temperature of the cooling crystallization is 22-28°C. Finally, the second solid-liquid mixture after crystallization is subjected to solid-liquid separation, using plate and frame filtration or vacuum negative pressure filtration, and the separated solid is washed with water and dried to obtain the sebacic acid product; Optional step: placing the sebacic acid product obtained after the refined treatment in water at 95-105°C, with the mass fraction of sebacic acid in the water being 20-30wt%, and keeping the temperature for 30-90 minutes. After the end of the heat preservation, the temperature is lowered to 30-50°C, and then solid-liquid separation is performed by centrifugal filtration or plate and frame filtration. The sebacic acid after solid-liquid separation is washed with water and then dried by paddle drying or airflow drying.

2. The method for extracting sebacic acid according to claim 1, wherein The acid includes one or more of sulfuric acid, hydrochloric acid, and acetic acid, and the base includes one or more of sodium hydroxide, potassium hydroxide, and ammonia water.

3. The method for extracting sebacic acid according to claim 1, wherein: During the production of sebacic acid by microbial fermentation, the pH of the fermentation system during the bacterial growth phase is controlled at 3.5-6.5, and the pH of the fermentation system during the conversion phase is controlled at 4.5-6.

5.

4. The method for extracting sebacic acid according to claim 1, wherein: The acid used to adjust the pH value of the filtrate is sulfuric acid or hydrochloric acid.

5. The method for extracting sebacic acid according to claim 1, wherein: In the acidification crystallization step, when adjusting the pH value of the filtrate, the acid solution is added dropwise, and the dropping speed is such that the pH value of the solution decreases by 0.1-0.3 per minute.

6. The method for extracting sebacic acid according to claim 1, wherein: In the refining step, when the organic solvent is acetic acid, its purity is ≥99%.

7. The method for extracting sebacic acid according to claim 1, wherein: In an optional step, during the drying process, the rotation speed of the paddle drying is 30-50 rpm, and the temperature of the airflow drying is 120-150°C.