CN118530111A - A method for extracting and separating succinic acid from fermentation broth - Google Patents

Abstract

The present invention provides a method for extracting and separating succinic acid from a fermentation broth, comprising: acidifying the fermentation broth with a strong acid reagent, collecting the supernatant after centrifugation to obtain an acidified liquid; decolorizing the acidified liquid with activated carbon to obtain a decolorized clear liquid; extracting the decolorized clear liquid with a lipid organic solvent to obtain a first extraction phase and a first raffinate phase; extracting the first raffinate phase with a lipid organic solvent to obtain a second extraction phase and a second raffinate phase; combining the first extraction phase and the second extraction phase, concentrating, and crystallizing to obtain succinic acid. The method provided by the present invention is to extract succinic acid with an ester organic solvent under acidic conditions. The method not only has excellent extraction selectivity and high extraction efficiency, but also has strong reusability, mild process conditions, and high economic benefits.

Description

A method for extracting and separating succinic acid from fermentation broth

Technical Field

The invention belongs to the technical field of biochemical engineering, and in particular relates to a method for extracting and separating succinic acid from fermentation liquid.

Background Art

Succinic acid, also known as succinic acid, is a dibasic organic carboxylic acid that is commonly found in animals, plants and microorganisms. Succinic acid is an intermediate metabolite of the tricarboxylic acid cycle and an intermediate in the synthesis of a variety of complex organic substances. After reaction, it can be derived into a variety of compounds and is widely used in food, medicine, cosmetics, agriculture and basic chemical raw materials. In the chemical industry, succinic acid and its various derivatives are used as important raw materials and intermediates for a variety of industrial products such as green solvents, dyes and cosmetics, and can also be used as a variety of functional additives, such as solubilizers and emulsifiers. In the food industry, succinic acid and its salts can be used as flavoring agents, acidulants, pH regulators, etc. in a variety of foods. In the pharmaceutical industry, succinic acid can be used to synthesize sulfonamides, vitamin A, vitamin B, anticonvulsant drugs, etc. In addition, succinic acid can be used as a growth promoter to pretreat seeds to improve the germination rate of seeds, and can also be used as a herbicide in the agricultural field.

There are three main methods for preparing succinic acid: chemical synthesis, biotransformation and fermentation. Among them, the production of succinic acid by microbial fermentation is not only green and environmentally friendly, low cost, but also meets the requirements of sustainable development. At present, the methods for extracting succinic acid from the fermentation broth producing succinic acid mainly include calcium salt precipitation, solvent extraction and ion exchange adsorption. The calcium salt precipitation method is to add calcium salt to the solution to generate calcium succinate precipitation, and then acidify and desalt to obtain succinic acid. This method is mature in technology, but there are problems such as low succinic acid yield, high energy consumption, and a large amount of solid waste. The ion exchange method for adsorption and separation of succinic acid has the characteristics of good adsorption performance, high selectivity, and simple operation, but there are problems such as limited ion column exchange capacity, large resin dosage, cumbersome regeneration, and large amount of wastewater. Compared with the above two methods, the solvent extraction method has the advantages of high production capacity and low energy consumption.

According to the results of domestic market research, the market demand for succinic acid in 2020 is 1.8 million tons, and the global succinic acid market is expected to reach US$1.8 billion by 2025. Therefore, it is of great significance to develop a method for extracting and separating succinic acid from fermentation broth with high extraction efficiency and green environmental protection.

Summary of the invention

In order to solve the problems of high energy consumption and high cost in the process of extracting succinic acid from fermentation broth in the prior art, the present invention provides a method for extracting and separating succinic acid from fermentation broth by solvent extraction, wherein succinic acid is extracted by using an ester organic solvent under acidic conditions. The method has excellent extraction selectivity and high extraction efficiency, and is highly reusable, has mild process conditions, and has high economic benefits.

The technical solution adopted by the present invention is: a method for extracting and separating succinic acid from a fermentation broth, comprising the following steps:

Step 1: Acidify the fermentation liquid with a strong acid reagent, collect the supernatant after centrifugation to obtain the acidified liquid;

Step 2: Decolorizing the acidified liquid with activated carbon to obtain a decolorized clear liquid;

Step 3: extracting the decolorized clear liquid with a lipid organic solvent to obtain a first extraction phase and a first raffinate phase;

Step 4: extracting the first raffinate phase with a lipid organic solvent to obtain a second extraction phase and a second raffinate phase;

Step 5: Combine the first extraction phase and the second extraction phase, concentrate and crystallize to obtain succinic acid.

The principle of solvent extraction of succinic acid is mainly that succinic acid and other impurity components in the fermentation broth have different solubility in the extractant. Generally, succinic acid enters the extraction phase, and most of the impurities remain in the aqueous phase. Then, a succinic acid crystal sample is obtained through reduced pressure concentration, crystallization, and drying steps. Ester extractants not only have low polarity and high solubility, but are also reusable. The present invention first acidifies and decolorizes the fermentation broth so that the pH value of the decolorized clear liquid is less than the succinic acid dissociation constant pKa1=4.16, thereby inhibiting the dissociation process of H+ in the succinate ion in water, so that succinic acid is in a molecular state in water, thereby changing the distribution coefficient of succinic acid in the aqueous phase and the organic phase, so that it can be separated from water by extraction using organic solvents such as esters. Compared with the ionic succinate ion, the molecular succinic acid is more hydrophobic and is more easily extracted into the relatively more hydrophobic organic phase.

Preferably, the concentration of succinic acid in the acidified liquid in step 1 is 15 to 40 g/L. The fermentation liquid containing succinic acid is acidified and centrifuged to obtain an acidified liquid. The pigment in the acidified liquid can be safely and efficiently removed by activated carbon. The pigment generally comes from the fermentation raw materials, bacterial metabolism or colored substances produced by side reactions during the fermentation process. It is understandable that the fermentation supernatant after decolorization can also be concentrated before being acidified, so that the concentration of succinic acid in the acidified liquid is 15 to 40 g/L, more preferably 15 to 20 g/L, so as to facilitate the subsequent extraction of succinic acid.

Preferably, the pH of the acidified solution in step 1 is 1.8 to 4. In order to make succinic acid in a molecular state in the aqueous phase, the fermentation broth should be acidified according to the dissociation constant of succinic acid (pKa1=4.16) so that the pH of the acidified solution is 1.8 to 4, more preferably 1.8 to 2.

Preferably, in step 1, at least one of hydrochloric acid, sulfuric acid and phosphoric acid is used for acidification, preferably 36% to 38% concentrated hydrochloric acid is used to acidify the decolorized fermentation supernatant, so that the pH of the acidified liquid is preferably 1.8 to 2.

Preferably, in step three, the lipid organic solvent is selected from at least one of ethyl acetate, n-butyl acetate, isobutyl acetate, dibutyl phthalate and ethyl laurate.

Preferably, the volume ratio of the decolorized supernatant to the lipid organic solvent in step 3 is 1: (1-3), more preferably 1: 2. During the extraction process, the volume ratio of the extractant, i.e., the lipid organic solvent, to the decolorized supernatant should be considered to ensure that succinic acid is effectively separated from the decolorized supernatant with a smaller amount of lipid organic solvent.

Preferably, the extraction temperature in step three is 10-30° C., more preferably 20-28° C., to ensure higher extraction efficiency and extraction effect.

Preferably, the volume ratio of the first raffinate phase to the lipid organic solvent in step 4 is 1:(1-3), more preferably 1:2. In order to improve the extraction efficiency, the present invention performs a secondary extraction on the first raffinate phase produced by the first extraction. In the secondary extraction process, the first raffinate phase is preferably extracted using the same type and volume of lipid organic solvent as in step 2 as the extractant.

Preferably, the extraction temperature in step 4 is 10-30°C, more preferably 20-28°C, to ensure higher extraction efficiency and extraction effect.

Preferably, in step 5, concentration is performed at 20-40°C and vacuum degree -0.1MPa, and crystallization is performed at 1-4°C. Furthermore, step 5 may also include post-treatment of the obtained succinic acid to remove organic solvents as much as possible to improve the purity of the succinic acid product. The post-treatment generally includes: redissolving the obtained crude succinic acid product in water, crystallizing again, and drying to obtain the finished succinic acid product.

Beneficial effects of the present invention:

1. Excellent extraction selectivity: Under acidic conditions, ester organic solvents can effectively separate succinic acid from water and increase the yield of succinic acid.

2. High extraction efficiency: Through secondary extraction, the extraction rate of succinic acid can be further improved, thereby increasing the product yield.

3. Mild process conditions: The extractant used in the present invention is environmentally friendly and has mild process conditions, which is conducive to reducing production costs.

4. High economic benefits: Compared with the prior art, the method provided by the present invention has a higher yield and purity of succinic acid, and the ester organic solvent used can be reused, reducing the generation of wastewater and waste gas.

DETAILED DESCRIPTION

The following is an explanation of the embodiments of the present invention by specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied by other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. In the embodiments of the present invention, the methods used are all conventional methods unless otherwise specified, and the reagents used can be obtained from commercial sources.

Embodiment 1～5:

Examples 1 to 5 provide a method for extracting and separating succinic acid from a fermentation broth, using ethyl acetate, n-butyl acetate, isobutyl acetate, dibutyl phthalate, and ethyl laurate as lipid organic solvents and extractants to extract and separate succinic acid from the fermentation broth. Specifically, the following steps are included:

Step 1: Acidify the fermentation broth with 36% concentrated hydrochloric acid, collect the supernatant after centrifugation to obtain 1L of acidified liquid (pH=1.8, succinic acid concentration of 19.18 g/L);

Step 2: Decolorizing the acidified liquid using activated carbon (powdered activated carbon, 200 mesh) to obtain a decolorized clear liquid;

Step 3: extract the decolorized clear liquid with 2L of ester organic solvent at an extraction temperature of 28°C, shake for 2min, and stand for stratification to obtain 2L of the first extraction phase and 1L of the first raffinate phase;

Step 4: Use 2L of the same ester organic solvent as in step 2 to extract 1L of the first raffinate phase, the extraction temperature is 28°C, shake for 2min, and stand for stratification to obtain 2L of the second extraction phase and 1L of the second raffinate phase;

Step 5: After combining the first extraction phase and the second extraction phase, evaporate and concentrate at 30°C and a vacuum degree of -0.1 MPa, cool and crystallize at 4°C to obtain crude succinic acid, add water to dissolve, cool and crystallize again at 4°C, and dry for 4 hours to obtain the finished succinic acid. The specific results are shown in Table 1.

Table 1. Effects of different lipid organic solvents on extraction

Lipid organic solvents Succinic acid(g) Recovery rate (%) purity(%) Example 1 Ethyl acetate 13.81 72 99.56 Example 2 n-Butyl acetate 7.84 40.87 99.43 Example 3 Isobutyl acetate 7.32 38.15 99.48 Example 4 Dibutyl phthalate 3.37 17.58 99.53 Example 5 Ethyl laurate 3.89 20.27 99.67

As shown in Table 1, when different ester organic solvents are used to extract succinic acid in the fermentation broth, ethyl acetate (Example 1) as an extractant has a better extraction selectivity, and the recovery rate of the product succinic acid reaches 72%, and the purity is 99.16%.

Embodiment 6:

Example 6 provides a method for extracting and separating succinic acid from a fermentation broth, which specifically comprises the following steps:

Step 1: Acidify the fermentation broth with 36% concentrated hydrochloric acid, collect the supernatant after centrifugation to obtain 500 mL of acidified liquid (pH = 3.5, succinic acid concentration of 17.87 g/L);

Step 2: Decolorizing the acidified liquid using activated carbon (powdered activated carbon, 200 mesh) to obtain a decolorized clear liquid;

Step 3: extract the decolorized clear liquid with 1L ethyl acetate at an extraction temperature of 20°C, shake for 2min, and stand for stratification to obtain 1L of the first extraction phase and 500mL of the first raffinate phase;

Step 4: extract 500 mL of the first raffinate phase with 1 L of ethyl acetate at an extraction temperature of 20° C., shake for 2 min, and stand for stratification to obtain 1 L of the second extract phase and 500 mL of the second raffinate phase;

Step 5: After combining the first extract phase and the second extract phase, evaporate and concentrate them at 30°C and a vacuum degree of -0.1 MPa, cool and crystallize them at 4°C to obtain crude succinic acid, add water to dissolve them, cool and crystallize them again at 4°C, and dry them for 4 hours to obtain 6.19g of finished succinic acid, with a recovery rate of 69.3% and a product purity of 99.85%.

Embodiment 7:

Example 7 provides a method for extracting and separating succinic acid from a fermentation broth, which specifically comprises the following steps:

Step 1: Acidify with 36% concentrated hydrochloric acid, collect the supernatant after centrifugation to obtain 1L of acidified solution (pH=3.5, succinic acid concentration is 18.99 g/L);

Step 2: Decolorizing the acidified liquid using activated carbon (powdered activated carbon, 200 mesh) to obtain a decolorized clear liquid;

Step 3: extract the decolorized clear liquid with 2L ethyl acetate at an extraction temperature of 15°C, shake for 2min, and stand for stratification to obtain 2L of the first extraction phase and 1L of the first raffinate phase;

Step 4: extract 1L of the first raffinate phase with 2L of ethyl acetate at an extraction temperature of 15°C, shake for 2min, and stand for stratification to obtain 2L of the second extract phase and 1L of the second raffinate phase;

Step 5: After combining the first extraction phase and the second extraction phase, evaporate and concentrate them at 30°C and a vacuum degree of -0.1 MPa, cool and crystallize them at 4°C to obtain crude succinic acid, redissolve them in water, cool and crystallize them again at 4°C, and dry them for 4 hours to obtain 12.95g of finished succinic acid, with a recovery rate of 68.2% and a product purity of 99.77%.

Embodiment 8:

Example 8 provides a method for extracting and separating succinic acid from a fermentation broth, which specifically comprises the following steps:

Step 1: Acidify with 36% concentrated hydrochloric acid, collect the supernatant after centrifugation to obtain 200 mL of acidified solution (pH = 1.8, succinic acid concentration of 19.18 g/L);

Step 2: Decolorizing the acidified liquid using activated carbon (powdered activated carbon, 200 mesh) to obtain a decolorized clear liquid;

Step 3: extract the decolorized clear liquid with 300 mL of ethyl acetate at an extraction temperature of 28°C, shake for 2 minutes, and stand for stratification to obtain 300 mL of the first extraction phase and 200 mL of the first raffinate phase;

Step 4: extracting 200 mL of the first raffinate phase with 300 mL of ethyl acetate at an extraction temperature of 28° C., shaking for 2 min, and standing to separate layers to obtain 300 mL of the second extract phase and 200 mL of the second raffinate phase;

Step 5: After combining the first extract phase and the second extract phase, evaporate and concentrate at 30°C and a vacuum degree of -0.1 MPa, cool and crystallize at 4°C to obtain crude succinic acid, redissolve it in water, cool and crystallize it again at 4°C, and dry it for 4 hours to obtain 4.46g of finished succinic acid, with a recovery rate of 61.5% and a product purity of 99.3%.

Combining Example 1 with Examples 6 and 7, it can be seen that, under the same ester organic solvent, acidified liquid, and ester organic solvent volume, the acidified liquid with a lower pH value can further improve the extraction efficiency, and the recovery rate of succinic acid in Example 1 is 2.7% higher than that in Example 6. Combining Example 1 with Example 8, it can be seen that, under the same ester organic solvent, acidified liquid, and extraction temperature, appropriately increasing the extractant can improve the extraction efficiency, and the recovery rate of succinic acid in Example 1 is 10.5% higher than that in Example 8.

Comparative Example 1:

Compared with Example 1, Comparative Example 1 only performs one extraction and separation on the fermentation supernatant, which specifically includes the following steps:

Step 1: Acidify with 36% concentrated hydrochloric acid, collect the supernatant after centrifugation to obtain 500 mL of acidified solution (pH = 1.8, succinic acid concentration of 19.18 g/L);

Step 2: Decolorizing the acidified liquid using activated carbon (powdered activated carbon, 200 mesh) to obtain a decolorized clear liquid;

Step 3: extract the decolorized clear liquid with 1L of ester organic solvent at an extraction temperature of 28°C, shake for 2min, and stand for stratification to obtain 1L of the first extraction phase and 500mL of the first raffinate phase;

Step 4: The first extract phase was evaporated and concentrated at 30°C and a vacuum degree of -0.1 MPa, and cooled and crystallized at 4°C to obtain crude succinic acid, which was redissolved in water and cooled and crystallized again at 4°C. After drying for 4 hours, 4.86 g of finished succinic acid was obtained, with a recovery rate of 50.69% and a product purity of 99.38%.

Combining Example 1 and Comparative Example 1, it can be seen that using an ester organic solvent to perform secondary extraction on the fermentation supernatant can significantly improve the recovery rate of succinic acid, fully utilize the raw fermentation liquid, and save production costs.

The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope of the present invention.

Claims (10)

1. A method for extracting and separating succinic acid from fermentation broth, which is characterized by comprising the following steps:

step one: acidifying the fermentation liquor by using a strong acid reagent, centrifuging and collecting supernatant to obtain an acidified liquor;

Step two: decolorizing the acidified solution by using activated carbon to obtain decolorized clear solution;

step three: extracting the decolorized clear solution by using a lipid organic solvent to obtain a first extract phase and a first raffinate phase;

Step four: extracting the first raffinate phase by using a lipid organic solvent to obtain a second extract phase and a second raffinate phase;

step five: and merging the first extraction phase and the second extraction phase, and concentrating and crystallizing to obtain the succinic acid.

2. The method of claim 1, wherein the concentration of succinic acid in the acidified solution in step one is 15 to 40g/L.

3. The method of claim 1, wherein the pH of the acidified solution in step one is from 1.8 to 4.

4. The method of claim 1, wherein the lipid organic solvent in step three is selected from at least one of ethyl acetate, n-butyl acetate, isobutyl acetate, dibutyl phthalate, and ethyl laurate.

5. The method of claim 1, wherein the volume ratio of the acidified solution to the lipid organic solvent in step three is 1:1-3.

6. The method of claim 5, wherein the volume ratio of acidified solution to ethyl acetate in step three is 1:2.

7. The process according to claim 1, wherein the extraction temperature in step three is 10 to 30 ℃.

8. The process of claim 1, wherein the volume ratio of the first raffinate phase to the lipid organic solvent in step four is 1: (1-3).

9. The process of claim 8, wherein the volume ratio of the first raffinate phase to the lipid organic solvent in step four is 1:2.

10. The process according to claim 1, wherein the extraction temperature in step four is from 10 to 30 ℃.