Method for separating malic acid and succinic acid

Abstract

The invention provides a method for separating malic acid and succinic acid, which comprises the following steps: enabling a mixed solution containing malic acid and succinic acid to flow through an adsorption column filled with non-polar macroporous adsorption resin for adsorption, and then carrying out first water top washing so as to separate malic acid from succinic acid. The method has the advantages of simple operation, environmental protection, low production cost and the like, and solves the problems that a large amount of acid-base is used and a large amount of generated acid-base regeneration wastewater is difficult to treat in an anion resin adsorption-desorption method in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of organic acid separation, and in particular to a method for separating malic acid and succinic acid. Background Art

[0002] Malic acid, also known as 2-hydroxysuccinic acid, has two isomers due to an asymmetric carbon atom in the molecule: D-type and L-type. It is a white crystal or crystalline powder, has strong hygroscopicity, is easily soluble in water and ethanol, and has a special pleasant sour taste. Malic acid has a wide range of uses. In the food industry, it can be used as an acidulant, color retainer, preservative and emulsifier stabilizer, etc. In the chemical industry, it can be used as a synthetic raw material for descaling agents and fluorescent brighteners. It can be used as a raw material for the production of special-purpose plastics for polyester resins and alkyd resins. It also has important applications in the pharmaceutical field. Succinic acid, also known as succinic acid, 1,2-ethanedicarboxylic acid, is a C4 dicarboxylic acid, an intermediate of the TCA cycle, a colorless crystal, sour taste, soluble in water, ethanol and ether, insoluble in chloroform and dichloromethane. As an important organic chemical raw material and intermediate, succinic acid is mainly used in the pharmaceutical industry, food industry, and chemical industry. It can be used as an analytical reagent, food iron fortifier, and can also be used to prepare electroplating solutions and PCB circuit board solutions.

[0003]

[0004] The existing methods for producing malic acid mainly include chemical synthesis, enzyme method, and fermentation method. At present, the fermentation method is low-cost and environmentally friendly to produce malic acid. These three methods will produce a certain amount of succinic acid during the production of malic acid. Since succinic acid accounts for a small proportion and has a lower solubility than malic acid, it is impossible to completely separate the two by concentration and crystallization. Therefore, if you want to obtain high-purity malic acid, it is still an industry problem to achieve complete separation of the two.

[0005] At present, the commonly used methods for separating malic acid and succinic acid mainly include anion exchange resin adsorption analysis method and solvent extraction method. The anion resin adsorption analysis method mainly adsorbs malic acid and succinic acid in the sample to be processed on anion exchange resin, and then uses dilute sulfuric acid for analysis to obtain succinic acid analysis solution and malic acid analysis solution. However, the disadvantage of this method is that the adsorption capacity of such anion exchange resin is not high, the amount of water washing is large, and a large amount of acid and alkali reagents are required to regenerate the resin, which will produce a large amount of difficult-to-treat acid and alkali wastewater, and the acid analysis selectivity is not high, resulting in low product purity and yield. When solvent extraction is used to separate malic acid and succinic acid, there is a problem of high process cost. At the same time, due to the weak polarity of succinic acid, conventional organic solvents are difficult to extract, which will also cause problems such as low product purity and high solvent residue.

[0006] In summary, the existing methods for separating malic acid and succinic acid either require the use of a large amount of acid-base reagents, a large amount of water washing, or have problems such as high production costs, low product purity, and high solvent residues. Therefore, it is necessary to develop a new method for separating succinic acid and malic acid to improve the above problems. Summary of the invention

[0007] The main purpose of the present invention is to provide a method for separating malic acid and succinic acid, so as to solve the problems existing in the prior art when separating malic acid and succinic acid, such as high production cost, low product purity, low yield, or high solvent residue.

[0008] In order to achieve the above-mentioned object, according to one aspect of the present invention, a method for separating malic acid and succinic acid is provided, the method comprising: passing a mixed solution containing malic acid and succinic acid through an adsorption column filled with a non-polar macroporous adsorption resin for adsorption, and then performing a first water top wash to separate malic acid and succinic acid.

[0009] Furthermore, the specific surface area of ​​the macroporous adsorption resin is 1000-1100m 2 / g, the average pore diameter is 400-500nm, and the pore volume is 0.8-0.9mL / g.

[0010] The macroporous adsorption resin is in a granular form, and its particle size is 300 to 500 μm.

[0011] Furthermore, the height-to-diameter ratio of the filled non-polar macroporous adsorption resin is 10-13:1.

[0012] Furthermore, the macroporous adsorption resin is selected from Lanxiao Technology LX-8000N and / or LX-8000B.

[0013] Furthermore, the column passing temperature of the mixed solution of malic acid and succinic acid is 25-70°C, and the top washing temperature of the first water top washing is 25-70°C.

[0014] Furthermore, the feed amount of the mixed solution of malic acid and succinic acid introduced into the adsorption column is 0.2-0.6 bv, and more preferably 0.2-0.4 bv.

[0015] Furthermore, during the first water top wash process, the water feed flow rate is 1 to 5 bv / h, and more preferably 1 to 3 bv / h.

[0016] Furthermore, the mixed solution of malic acid and succinic acid includes 0.1 to 150 g / L of malic acid and 0.1 to 100 g / L of succinic acid.

[0017] Furthermore, the mixed solution of malic acid and succinic acid is derived from malic acid fermentation broth and is obtained by the following preparation method: the malic acid fermentation broth is successively centrifuged and filtered to obtain a filtrate, and the filtrate is acidified to obtain a mixed solution of malic acid and succinic acid; preferably, the acidification is carried out using sulfuric acid acidification, and the pH value of the acidified filtrate is 1.0 to 2.5.

[0018] Furthermore, after the acidification treatment, the preparation method further comprises: subjecting the acidified liquid to cation exchange resin adsorption, a second water top wash, an anion exchange resin adsorption, a third water top wash, and decolorization in sequence to obtain a mixed solution of malic acid and succinic acid; preferably, the mixed solution of malic acid and succinic acid prepared from the malic acid fermentation broth comprises 10 to 50 g / L of malic acid and 12 to 45 g / L of succinic acid.

[0019] The method for separating malic acid and succinic acid of the present invention utilizes the principle of continuous chromatographic separation, is simple to operate, and has good separation effect. The obtained malic acid and succinic acid have high purity and high yield. The entire separation and extraction process is clean, green, environmentally friendly, and has low production cost. The method overcomes the problems of the anion resin adsorption and analysis method in the prior art, such as the use of a large amount of acid and alkali, the difficulty in treating a large amount of acid and alkali wastewater generated, insufficient adsorption capacity, large amount of water washing, low analytical selectivity, low product purity and yield, etc.; meanwhile, the method also avoids the problems of high cost, difficulty in stripping, high solvent residue, etc. of the solvent extraction method. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0021] As described in the background technology section of this application, the existing methods for separating malic acid and succinic acid either have the problem that the anion exchange resin adsorption analysis method requires the use of a large amount of acid and alkali reagents, the amount of water washing is large, resulting in low product purity and yield, or the extraction method has the problem of high production cost, low product purity, and high solvent residue. In order to solve this problem, the present application provides a method for separating malic acid and succinic acid, which comprises: passing a mixed solution containing malic acid and succinic acid through an adsorption column filled with a non-polar macroporous adsorption resin for adsorption, and then a first water top wash to separate malic acid and succinic acid.

[0022] The applicant discovered that the forces between malic acid, succinic acid and non-polar macroporous adsorption resin are different. In the adsorption process of a mixed solution containing malic acid and succinic acid flowing through an adsorption column filled with a macroporous adsorption resin, malic acid has a stronger polarity and will not be adsorbed on the macroporous adsorption resin, but will directly flow out with the feed liquid. Succinic acid has a weaker polarity, and due to the weak van der Waals force between the macroporous adsorption resin and succinic acid, a weak induction force is generated, which causes succinic acid to flow out only in the subsequent first water top wash stage. The present application achieves the beneficial effect of effectively separating malic acid and succinic acid by having different distribution coefficients for malic acid and succinic acid in a system of macroporous adsorption resin and water.

[0023] In summary, the method for separating malic acid and succinic acid of the present invention utilizes the principle of continuous chromatographic separation, is simple to operate, and has good separation effect. The obtained malic acid and succinic acid have high purity and high yield. The entire separation and extraction process is clean, green, environmentally friendly, and has low production cost. It overcomes the problems of the anion resin adsorption and analysis method in the prior art, such as the use of a large amount of acid and alkali, the generation of a large amount of acid and alkali wastewater that is difficult to handle, insufficient adsorption capacity, large water washing volume, low analytical selectivity, low product purity and yield, etc.; it also avoids the problems of high cost, difficult stripping, high solvent residue, etc. of the solvent extraction method.

[0024] In order to further improve the product purity and yield of malic acid and succinic acid, the macroporous adsorption resin is preferably a resin with a specific surface area of ​​1000 to 1100 m 2 / g, a non-polar adsorption resin with an average pore size of 400-500nm and a pore volume of 0.8-0.9mL / g.

[0025] In a preferred embodiment, the macroporous adsorption resin has a granular shape and a particle size of 300 to 500 μm. When the particle size of the macroporous adsorption resin is controlled within the above range, the adsorption performance of the macroporous adsorption resin is better. When the particle size is too small, the resistance to the fluid is too large during use, affecting the separation effect. When the particle size is too large, the adsorption of the macroporous adsorption resin decreases.

[0026] In order to further improve the product purity and yield of malic acid and succinic acid, in a preferred embodiment, the height-to-diameter ratio of the filled non-polar macroporous adsorption resin is 10-13:1.

[0027] In a preferred embodiment, the macroporous adsorption resin is selected from Lanxiao Technology LX-8000N and / or LX-8000B. The present invention selects the above-mentioned macroporous adsorption resin because of its high selectivity for malic acid and succinic acid. The polarity of succinic acid is weak, and there is a weak induction force between the macroporous adsorption resin and the macroporous adsorption resin, so that succinic acid will flow out in the subsequent first water washing stage, while the polarity of malic acid is strong, and the interaction force with the above-mentioned macroporous adsorption resin is weak, and it flows out directly with the feed liquid. The effective separation of malic acid and succinic acid can be effectively achieved by the difference in the interaction force between the two organic acids and the above-mentioned macroporous adsorption resin. At the same time, the macroporous adsorption resin selected in this application has a weak polarity and can be regenerated by eluting with highly polar water, avoiding the use of a large amount of organic solvents, high solvent residues, wastewater treatment, and high costs. More preferably, LX-8000N.

[0028] In order to further improve the separation effect of malic acid and succinic acid and enhance the purity and yield of the product, the column temperature of the mixed solution of malic acid and succinic acid is controlled at 25-70°C and the top wash temperature of the first water top wash is controlled at 25-70°C to ensure that the material does not precipitate during the separation process.

[0029] In order to further improve the separation effect of malic acid and succinic acid and improve the purity and yield of the product, the feed amount of the mixed solution of malic acid and succinic acid into the adsorption column is 0.2-0.6 bv. In some optional embodiments, the feed amount of the adsorption column can be 0.2 bv, 0.25 bv, 0.3 bv, 0.35 bv, 0.4 bv, 0.45 bv, 0.5 bv, 0.55 bv, 0.6 bv; more preferably 0.2-0.4 bv.

[0030] In order to further improve the separation effect of malic acid and succinic acid and improve the purity and yield of the product, during the first top wash, the feed flow rate of water is preferably 1-5 bv / h. In some optional embodiments, the feed flow rate of water is 1 bv / h, 1.5 bv / h, 2 bv / h, 2.5 bv / h, 3 bv / h, 3.5 bv / h, 4 bv / h, 4.5 bv / h, 5 bv / h; more preferably 1-3 bv / h.

[0031] In a preferred embodiment, during the first top wash, the amount of top wash water is preferably 2.8 to 3.5 bv. By controlling the amount of top wash water within the above range, the malic acid and succinic acid adsorbed by the macroporous adsorption resin can be fully top washed out, effectively improving the purity and yield of the product, while also avoiding ineffective elution. In order to further improve the separation effect of malic acid and succinic acid, the mixed solution of malic acid and succinic acid includes: 0.1 to 150 g / L of malic acid and 0.1 to 100 g / L of succinic acid. More preferably, the mixed solution of malic acid and succinic acid includes: 10 to 50 g / L of malic acid and 12 to 45 g / L of succinic acid. The present invention limits the mass concentration of malic acid and succinic acid within the above range in order to facilitate the effective separation of malic acid and succinic acid and improve the purity and yield of the product.

[0032] In a preferred embodiment, the mixed solution of malic acid and succinic acid is derived from malic acid fermentation broth and is obtained by the following preparation method: the malic acid fermentation broth is centrifuged and filtered in sequence to obtain a filtrate, and the filtrate is acidified to obtain the mixed solution of malic acid and succinic acid.

[0033] The mixed solution containing malic acid and succinic acid in the present application can be directly derived from malic acid fermentation liquid. It is further explained here that malic acid fermentation liquid is generally fermented with glucose as substrate using engineered bacteria that produce L-malic acid, and calcium carbonate is added during the fermentation process. The malic acid and succinic acid in the malic acid fermentation liquid system are mainly in the form of calcium malate and calcium succinate. The present invention first centrifuges and filters the malic acid fermentation liquid to remove organic acid salt precipitation (calcium malate and calcium succinate) and other precipitations in the malic acid fermentation liquid to obtain a fermentation liquid, and the fermentation liquid (filtrate) contains a small amount of organic acid salt dissolved in the aqueous phase, and the small amount of organic acid salt (calcium malate and calcium succinate) dissolved in the fermentation liquid (filtrate) is subsequently converted into corresponding organic acids (malic acid and succinic acid) by acidification treatment, that is, a mixed solution of malic acid and succinic acid is obtained.

[0034] In a preferred embodiment, the acidification treatment uses sulfuric acid acidification, and the pH value of the acidified filtrate is 1.0 to 2.5. The present invention uses the above acidification treatment method to convert the soluble calcium malate and calcium succinate in the malic acid fermentation liquid into a mixture of malic acid and succinic acid.

[0035] In order to further improve the purity of the malic acid and succinic acid mixed solution prepared from the malic acid fermentation broth, after the acidification treatment, the following steps are further included: the acidified solution is sequentially subjected to cation exchange resin adsorption, a second water top wash, anion exchange resin adsorption, a third water top wash, and decolorization to obtain the malic acid and succinic acid mixed solution. Impurities such as inorganic salts in the fermentation broth are removed by cation and anion exchange resins. The malic acid and succinic acid mixed solution obtained by the above preparation method includes 10 to 50 g / L of malic acid and 12 to 45 g / L of succinic acid.

[0036] The present invention passes the mixed solution of malic acid and succinic acid prepared by the above method into a non-polar macroporous adsorption resin for adsorption, and top washing can respectively obtain high-purity malic acid and succinic acid. Compared with the process of separating malic acid and succinic acid in malic acid fermentation broth in the prior art, the fermentation broth is saved from the acid analysis process after passing through anion exchange resin, and a large amount of acid-base regeneration wastewater is avoided from resin regeneration. The present invention adsorbs the mixed solution of malic acid and succinic acid through a non-polar macroporous adsorption resin, and top washing with water can obtain high-purity malic acid and succinic acid.

[0037] When malic acid fermentation broth is used to prepare a mixed solution of malic acid and succinic acid, the mixed solution containing malic acid and succinic acid is sequentially passed through an adsorption column filled with a macroporous adsorption resin for adsorption, and then subjected to a first water top wash, and after the first water top wash, a malic acid enriched solution and a succinic acid enriched solution are obtained. In order to obtain a malic acid product and a succinic acid product with a higher final purity, the method further comprises: the malic acid enriched solution and the succinic acid enriched solution are respectively subjected to reduced pressure concentration, crystallization, and drying to obtain malic acid crystals and succinic acid crystals, respectively. Preferably, the method further comprises: the malic acid enriched solution is sequentially subjected to a first concentration crystallization, a first centrifugation, a first filtration, and a first drying to obtain malic acid; the succinic acid enriched solution is sequentially subjected to a second concentration crystallization, a second centrifugation, a second filtration, and a second drying to obtain succinic acid.

[0038] It should be further explained here that the cation exchange resin and anion exchange resin used in the preparation of malic acid and succinic acid mixed solution using malic acid fermentation broth are both ion exchange resins with desalination function commonly used in the art. For example, the cation exchange resin can be D001FD from Beijing Zhengguang Venture Technology, and the anion exchange resin can be D318 from Beijing Zhengguang Venture Technology.

[0039] The method for separating malic acid and succinic acid of the present invention utilizes the principle of continuous chromatographic separation, is simple to operate, and has good separation effect. The obtained malic acid and succinic acid have high purity and high yield. The entire separation and extraction process is clean, green, environmentally friendly, and has low production cost. It overcomes the problems of the anion resin adsorption and analysis method in the prior art, such as the use of a large amount of acid and alkali, the generation of a large amount of acid and alkali wastewater that is difficult to treat, insufficient adsorption capacity, a large amount of water washing, and low analytical selectivity, resulting in low product purity and yield. It also avoids the problems of high cost, difficulty in stripping, high solvent residue, etc. of the solvent extraction method.

[0040] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0041] Example

[0042] Method for preparing a mixed solution of malic acid and succinic acid using malic acid fermentation broth:

[0043] After the malic acid fermentation liquid was inactivated, 50L of the inactivated fermentation liquid (including 150g / L malic acid and 25g / L succinic acid in terms of organic acid) was centrifuged and filtered to obtain 30L of filtrate; the filtrate was acidified with sulfuric acid to adjust the pH value of the filtrate from 4.5 to 1.8; the filtrate after the acidification was sequentially passed through a cation exchange resin (model D001FD, produced by Beijing Zhengguang Venture Technology Co., Ltd.), a second water top wash, an anion exchange resin (model D318, produced by Beijing Zhengguang Venture Technology Co., Ltd.), a third water top wash, and decolorization to obtain 33L of a mixed solution of malic acid and succinic acid. The obtained mixed solution of malic acid and succinic acid contains 20g / L malic acid and 20g / L succinic acid.

[0044] Example 1

[0045] The mixed solution of malic acid and succinic acid prepared above (malic acid 20 g / L, succinic acid 20 g / L) was introduced into an adsorption column filled with Lanxiao Technology LX-8000N macroporous adsorption resin (height-to-diameter ratio of 11.4:1) at a feed rate of 0.2 bv for adsorption at room temperature (25°C). The mixture was then subjected to a first water top wash (water feed rate of 1 bv / h, top wash water amount of 3.0 bv) at room temperature (25°C). Malic acid flowed out first and succinic acid flowed out later, so as to separate malic acid and succinic acid.

[0046] The malic acid-enriched liquid and the succinic acid-enriched liquid obtained by the first top wash are respectively subjected to reduced pressure concentration, crystallization and drying to obtain malic acid crystals and succinic acid crystals, respectively.

[0047] Example 2

[0048] The only difference from Example 1 is that during the first water top wash, the water feed flow rate is 3 bv / h.

[0049] Example 3

[0050] The only difference from Example 1 is that during the first water top wash, the water feed flow rate is 5 bv / h.

[0051] Example 4

[0052] The only difference from Example 2 is that the mixed liquid is introduced at a feed rate of 0.4 bv.

[0053] Example 5

[0054] The only difference from Example 2 is that the mixed liquid is introduced at a feed rate of 0.6 bv.

[0055] The separation effects of the mixed solution of malic acid and succinic acid in Examples 1-5 are shown in Table 1.

[0056] Table 1

[0057]

[0058] Example 6

[0059] The only difference from Example 1 is that the macroporous adsorption resin LX-8000N of Lanxiao Technology is replaced with the macroporous adsorption resin LX-8000B in equal volume.

[0060] Example 7

[0061] The only difference from Example 2 is that the macroporous adsorption resin of LX-8000N of Lanxiao Technology is replaced with the macroporous adsorption resin of LX-8000B in equal volume.

[0062] Example 8

[0063] The only difference from Example 3 is that the macroporous adsorption resin of LX-8000N of Lanxiao Technology is replaced with the macroporous adsorption resin of LX-8000B in equal volume.

[0064] Example 9

[0065] The only difference from Example 4 is that the macroporous adsorption resin of LX-8000N of Lanxiao Technology is replaced by the macroporous adsorption resin of LX-8000B in equal volume.

[0066] Example 10

[0067] The only difference from Example 5 is that the macroporous adsorption resin of LX-8000N of Lanxiao Technology is replaced by the macroporous adsorption resin of LX-8000B in equal volume.

[0068] The separation effects of the mixed solution of malic acid and succinic acid in Examples 6-10 are shown in Table 2.

[0069] Table 2

[0070]

[0071] Embodiment 11

[0072] A mixed solution of malic acid and succinic acid was prepared using standard malic acid and standard succinic acid: 100 g of malic acid and 100 g of succinic acid were dissolved in 40°C water and the volume was fixed to 1 L to form a mixed solution of malic acid and succinic acid containing 100 g / L of malic acid and 100 g / L of succinic acid.

[0073] The above mixed solution (100 g / L malic acid, 100 g / L succinic acid) was passed through an adsorption column filled with Lanxiao Technology's LX-8000N macroporous adsorption resin at a feed rate of 0.2 bv at a column temperature of 40°C, and then passed through the first water top wash (the water feed flow rate was 3 bv / h) at a water top wash temperature of 40°C. Malic acid flowed out first and succinic acid flowed out later, so as to separate malic acid and succinic acid.

[0074] The malic acid-enriched liquid and the succinic acid-enriched liquid obtained by the first top wash are respectively subjected to reduced pressure concentration, crystallization and drying to obtain malic acid crystals and succinic acid crystals, respectively.

[0075] The separation effect of the mixed solution of malic acid and succinic acid in Example 11 is shown in Table 3.

[0076] Table 3

[0077]

[0078] The yields and purities of succinic acid and malic acid prepared in Examples 1-11 of the present invention are shown in Table 4.

[0079] Product purity detection: Liquid chromatography HPLC was used to determine the purity of malic acid and succinic acid.

[0080] Product yield: Malic acid yield = mass of malic acid recovered / mass of malic acid in the mixture of malic acid and succinic acid; Succinic acid yield = mass of succinic acid recovered / mass of succinic acid in the mixture of malic acid and succinic acid.

[0081] Table 4

[0082]

[0083]

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for separating malic acid and succinic acid, characterized in that: The method comprises: The mixed solution containing malic acid and succinic acid is passed through an adsorption column filled with non-polar macroporous adsorption resin for adsorption, and then the first water top wash is performed to separate the malic acid and succinic acid.

2. The method for separating malic acid and succinic acid according to claim 1, characterized in that: The specific surface area of ​​the macroporous adsorption resin is 1000-1100m 2 / g, the average pore diameter is 400-500nm, and the pore volume is 0.8-0.9mL / g.

3. The method for separating malic acid and succinic acid according to any one of claims 1 to 2, characterized in that: The height-to-diameter ratio of the filled non-polar macroporous adsorption resin is 10-13:

1.

4. The method for separating malic acid and succinic acid according to any one of claims 1 to 3, characterized in that: The macroporous adsorption resin is selected from LX-8000N and / or LX-8000B of Lanxiao Technology.

5. The method for separating malic acid and succinic acid according to any one of claims 1 to 4, characterized in that: The column passing temperature of the mixed solution of malic acid and succinic acid is 25-70°C, and the top washing temperature of the first water top washing is 25-70°C.

6. The method for separating malic acid and succinic acid according to any one of claims 1 to 5, characterized in that: The feed amount of the mixed solution of malic acid and succinic acid passed into the adsorption column is 0.2-0.6 bv, and more preferably 0.2-0.4 bv.

7. The method for separating malic acid and succinic acid according to any one of claims 1 to 6, characterized in that: During the first water top washing process, the water feed flow rate is 1 to 5 bv / h, more preferably 1 to 3 bv / h.

8. The method for separating malic acid and succinic acid according to any one of claims 1 to 7, characterized in that: The mixed solution of malic acid and succinic acid comprises 0.1 to 150 g / L of malic acid and 0.1 to 100 g / L of succinic acid.

9. The method for separating malic acid and succinic acid according to any one of claims 1 to 8, characterized in that: The mixed solution of malic acid and succinic acid is derived from malic acid fermentation broth and is obtained by the following preparation method: Centrifuging and filtering the malic acid fermentation broth in sequence to obtain a filtrate, and acidifying the filtrate to obtain a mixed solution of malic acid and succinic acid; Preferably, the acidification treatment uses sulfuric acid acidification, and the pH value of the filtrate after acidification is 1.0-2.

5.

10. The method for separating malic acid and succinic acid according to claim 9, characterized in that: After the acidification treatment, the preparation method further comprises: subjecting the acidification liquid to cation exchange resin adsorption, second water top washing, anion exchange resin adsorption, third water top washing, and decolorization in sequence to obtain the mixed liquid of malic acid and succinic acid; Preferably, the mixed solution of malic acid and succinic acid prepared from malic acid fermentation broth comprises 10-50 g / L of malic acid and 12-45 g / L of succinic acid.

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