Succinic acid extraction agent and method for complexation extraction of succinic acid crystallization mother liquor

Abstract

The invention provides a succinic acid extracting agent and a method for complexing and extracting succinic acid crystallization mother liquor. The succinic acid extraction agent comprises a complexing agent and a cosolvent; the method for complexing and extracting the succinic acid crystallization mother liquor comprises the following steps: (1) normal-phase extraction: mixing the succinic acid crystallization mother liquor with the extracting agent, and extracting to obtain a succinic acid loaded organic phase; and (2) reverse extraction: mixing the succinic acid loaded organic phase obtained in the step (1) with a reverse extraction agent, and extracting to obtain succinic acid crystals and the extraction agent. By designing the composition of the succinic acid extraction agent and further through the synergistic effect of the complex and the cosolvent, the extraction effect of the extraction agent on the high-concentration succinic acid crystallization mother liquor is improved, and the positive extraction yield and the back extraction yield in the extraction process of the succinic acid crystallization mother liquor are balanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of biochemistry separation, and particularly relates to a succinic acid extractant and a method for complex extraction of succinic acid crystallization mother liquor. Background Art

[0002] Succinic acid is an important dibasic organic acid, which is used in the food, light industry and pharmaceutical industries, and can be used to prepare basic chemical products such as 1,4-butanediol, tetrahydrofuran, γ-butyrolactone, N-methylpyrrolidone, etc. It is also the main raw material of the new fully biodegradable plastic PBS (polybutylene succinate). The market demand has reached 50,000 tons / year, and the potential market reaches 3 million tons / year. At present, succinic acid is mostly produced by chemical methods. The chemical production of succinic acid mainly uses maleic anhydride as the raw material, which comes from non-renewable petroleum resources, and a large amount of pollution will also be generated during the production process. The biological method for preparing succinic acid can utilize renewable biomass resources, has the advantages of high efficiency, independence from petroleum, and low pollution, and can absorb and fix greenhouse gas CO2 gas during the biosynthesis process. In recent years, it has become a research and application hotspot at home and abroad.

[0003] The production process of succinic acid includes two stages. The first stage is to obtain succinic acid fermentation broth by using specific microorganisms for fermentation, and the second stage is to treat the succinic acid fermentation broth by some physical and chemical methods to extract the target product succinic acid from the fermentation broth. In the process of the second stage, succinic acid needs to go through the processes of evaporation and concentration, and cooling crystallization. Due to the certain solubility of succinic acid in water, it will not completely precipitate even at low temperatures. Therefore, a large amount of succinic acid crystallization mother liquor will be generated, and the concentration of the mother liquor is usually 10-110 g / L due to the difference in production processes. The main component of the succinic acid crystallization mother liquor is succinic acid, and at the same time, it contains impurities such as inorganic salts, small molecule soluble proteins and pigments. In industrial production, separating succinic acid from the succinic acid crystallization mother liquor can significantly improve the product yield and reduce the production cost.

[0004] In the prior art, the methods for separating succinic acid from succinic acid crystallization mother liquor include electrodialysis method and extraction method. Among them, the extraction method has high selectivity, high separation efficiency and low energy consumption for separating succinic acid from succinic acid crystallization mother liquor. However, the extractants disclosed in the prior art have poor extraction effects on succinic acid crystallization mother liquor, and have limitations such as strong forward extraction ability, weak back extraction ability and low concentration of crystallization mother liquor. Therefore, providing a new type of succinic acid extractant to improve the extraction effect on high-concentration succinic acid crystallization mother liquor has become an urgent technical problem to be solved at present. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a succinic acid extractant and a method for complex extraction of succinic acid crystallization mother liquor. In the present invention, by designing the composition of the succinic acid extractant, and further through the synergistic effect of the complex and the cosolvent, the extraction effect of the extractant on the high-concentration succinic acid crystallization mother liquor is improved, and the positive extraction yield and the back-extraction yield in the extraction process of the succinic acid crystallization mother liquor are balanced.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a succinic acid extractant, which is composed of a complexing agent and a cosolvent shown in the following formula I;

[0008]

[0009] Among them, R1 represents an ester group of C1-C10;

[0010] R2 and R3 each independently represent any one of an alkyl group of C1-C10, an ester group of C1-C10 or a hydroxyl group;

[0011] The cosolvent is an alcohol solvent containing 7-10 carbon atoms.

[0012] In the present invention, by designing the composition of the succinic acid extractant, and further through the synergistic effect of the complex and the cosolvent, through complex extraction, the extraction effect of the extractant on the high-concentration succinic acid crystallization mother liquor is improved, and the positive extraction yield and the back-extraction yield in the extraction process of the succinic acid crystallization mother liquor are balanced.

[0013] Compared with traditional physical extraction, complex extraction can provide a larger distribution coefficient. Complex extraction is based on the interaction between the Lewis acid (or base) functional group of the solute and the Lewis base (or acid) functional group of the extractant for separation, and the chemical bond energy of complex extraction is generally between 10-60 KJ / mol, with a moderate value, which can not only form a complex to achieve phase transfer, but also make the complexing agent easy to regenerate during back-extraction. The carboxyl group of succinic acid belongs to the Lewis acidic functional group. Therefore, the present invention prepares an extractant with excellent performance by using a complexing agent with a specific structure and an alcohol solvent with a Lewis basic functional group as the cosolvent.

[0014] In the present invention, the succinic acid extractant is composed of a phosphate ester complexing agent and an alcohol cosolvent. Compared with the single solvent provided by the prior art, the present invention utilizes the multi-component synergistic effect of the complexing agent and the cosolvent to form a mixed extractant system, which improves the solubility of the extractant for succinic acid in the normal-phase extraction process, can effectively reduce the viscosity of the system during reverse extraction, and improves the flow ability of succinic acid between the two phases. Generally speaking, by designing the composition of the succinic acid extractant, the present invention makes the yields of forward extraction and reverse extraction more balanced, and significantly improves the total recovery rate of succinic acid.

[0015] In the present invention, C1-10 can be C1, C2, C3, C4, C5, C6, C7, C8, C9 or C10.

[0016] The cosolvent is an alcohol solvent containing 7-10 (for example, it can be 7, 8, 9 or 10) carbon atoms.

[0017] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the purpose and beneficial effects of the present invention can be better achieved and realized.

[0018] As a preferred technical solution of the present invention, R1 represents any one of isooctyl ester group, dimethylheptyl ester group or 2-ethylhexyl ester group.

[0019] As a preferred technical solution of the present invention, R2 and R3 each independently represent any one of methyl, ethyl, propyl, hydroxyl, isooctyl ester group, dimethylheptyl ester group or 2-ethylhexyl ester group.

[0020] As a preferred technical solution of the present invention, the complexing agent is selected from any one or a combination of at least two of diisooctyl phosphate, dimethylheptyl methylphosphonate or mono-2-ethylhexyl 2-ethylhexyl phosphate.

[0021] In the present invention, the diisooctyl phosphate is

[0022] The dimethylheptyl methylphosphonate is

[0023] The mono-2-ethylhexyl 2-ethylhexyl phosphate is

[0024] In the present invention, by selecting a specific phosphate ester with a specific structural formula as the complexing agent, a succinic acid extractant with excellent performance is prepared.

[0025] The mechanism of complex extraction is a separation method based on the interaction between the Lewis acid (or base) functional groups of the solute and the Lewis base (or acid) functional groups in the extractant. Based on the Lewis acid-base theory, -COOH in succinic acid belongs to the Lewis acid functional group, so succinic acid is a Lewis acid. The P=O bond in phosphate ester belongs to the Lewis base functional group, and the P=O bond is a polar covalent bond with stable properties, large bond energy, and strong complexing ability. Therefore, using phosphate ester as a complexing agent and combining with a cosolvent to form a mixed extractant system can form a complex with succinic acid and improve the extraction efficiency.

[0026] As a preferred technical solution of the present invention, the cosolvent is selected from any one or a combination of at least two of n-heptanol, isooctanol, n-nonanol, or n-decanol.

[0027] In the present invention, by selecting an alcohol solvent with a specific number of carbon atoms as the cosolvent, a succinic acid extractant with excellent performance is prepared. If the number of carbon atoms in the alcohol solvent is too small, the flash point is low, the flammability increases, the hydrophobicity decreases, and the solubility in water increases, which is not conducive to extraction phase separation; if the number of carbon atoms in the alcohol solvent is too large, the solubility of the complex in the cosolvent decreases significantly, which is not conducive to back extraction.

[0028] As a preferred technical solution of the present invention, the volume ratio of the complexing agent to the cosolvent is 1:(0.1 - 10), for example, it can be 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10, etc., preferably 1:(1.5 - 8), and more preferably 1:(3 - 7).

[0029] In the present invention, by controlling the volume ratio of the complexing agent to the cosolvent within a specific range, an extractant with excellent performance is prepared, balancing the yields of forward extraction and reverse extraction, and significantly improving the total recovery rate of succinic acid.

[0030] In the second aspect, the present invention provides a method for complex extraction of succinic acid crystallization mother liquor, and the method includes the following steps:

[0031] (1) Forward extraction: Mix the succinic acid crystallization mother liquor with the forward extractant and extract to obtain a succinic acid-loaded organic phase;

[0032] (2) Back extraction: Mix the succinic acid-loaded organic phase obtained in step (1) with the back extractant and extract to obtain succinic acid crystals and the forward extractant;

[0033] The forward extractant includes the succinic acid extractant as described in the first aspect.

[0034] In the present invention, succinic acid crystals are prepared by normal-phase extraction and back extraction using a specific normal-phase extractant.

[0035] In the present invention, the extractions in step (1) and step (2) are each independently cross-flow extraction.

[0036] As a preferred technical solution of the present invention, the concentration of succinic acid in the succinic acid crystallization mother liquor is 10-110 g / L (for example, it can be 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L or 110 g / L, etc.), preferably 60-110 g / L.

[0037] In the present invention, the pH of the succinic acid crystallization mother liquor is 1.8-3.0, for example, it can be 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.0, etc.

[0038] In the present invention, the concentration of inorganic salt ions in the succinic acid crystallization mother liquor is: C(Na + ) is 1000-2000 ppm (for example, it can be 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm or 2000 ppm, etc.), C(Cl - ) is 100-500 ppm (for example, it can be 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm or 500 ppm, etc.), C(SO4 2- ) is 100-500 ppm (for example, it can be 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm or 500 ppm, etc.), C(PO4 3- ) is 200-1000 ppm (for example, it can be 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm or 1000 ppm, etc.), C(Fe 2+ ) is 100-1000 ppm (for example, it can be 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm or 1000 ppm, etc.).

[0039] As a preferred technical solution of the present invention, the volume ratio of the succinic acid crystallization mother liquor to the normal-phase extractant is 1:(1-5), for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, etc.

[0040] As a preferred technical solution of the present invention, the number of extraction stages in step (1) is 1-5 stages, for example, it can be 1 stage, 2 stages, 3 stages, 4 stages or 5 stages, etc.

[0041] Preferably, the extraction temperature in step (1) is 20-60°C, for example, it can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, etc.

[0042] As a preferred technical solution of the present invention, the back extractant includes water.

[0043] As a preferred technical solution of the present invention, the volume ratio of the succinic acid-loaded organic phase to the back extractant is 1:(1-5), for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, etc.

[0044] As a preferred technical solution of the present invention, the number of extraction stages in step (2) is 1-10 stages, for example, it can be 1 stage, 2 stages, 3 stages, 4 stages, 5 stages, 6 stages, 7 stages, 8 stages, 9 stages or 10 stages, etc.

[0045] Preferably, the extraction temperature in step (2) is 40-80°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, etc.

[0046] Preferably, after the extraction in step (2), a succinic acid product phase and an extractant are obtained, and after the extraction, it further includes steps of post-treating the succinic acid product phase and regenerating the extractant.

[0047] Preferably, the steps of post-treating the succinic acid product phase include evaporation and concentration, cooling crystallization, centrifugation and drying.

[0048] Preferably, the steps of regenerating the extractant include evaporating the extractant.

[0049] In the present invention, the extractant after regeneration treatment can be reused.

[0050] As a preferred technical solution of the present invention, the method for complex extraction of succinic acid crystallization mother liquor specifically includes the following steps:

[0051] (1) Normal-phase extraction: Mix the succinic acid crystallization mother liquor and the normal-phase extractant at a volume ratio of 1:(1-5), and perform cross-flow extraction (the number of stages is 1-5) at 20-60 °C to obtain the succinic acid-loaded organic phase and the raffinate phase;

[0052] Among them, the pH of the succinic acid crystallization mother liquor is 1.8-3.0, C(succinic acid) is 10-110 g / L, C(Na + ) is 1000-2000 ppm, C(Cl - ) is 100-500 ppm, C(SO4 2- ) is 100-500 ppm, C(PO4 3- ) is 200-1000 ppm, C(Fe 2 + ) is 100-1000 ppm;

[0053] The normal-phase extractant includes the succinic acid extractant described in the first aspect;

[0054] (2) Reverse extraction: Mix the succinic acid-loaded organic phase obtained in step (1) and the reverse extractant at a volume ratio of 1:(1-5), and perform cross-flow extraction (the number of stages is 1-10) at 40-80 °C to obtain the succinic acid product phase and the extractant;

[0055] Evaporate and concentrate the succinic acid product phase, cool and crystallize, centrifuge and dry to obtain succinic acid crystals;

[0056] Evaporate the extractant to obtain the regenerated extractant, which can be repeatedly used as the forward extractant for the complex extraction of succinic acid.

[0057] In the present invention, the extraction process of succinic acid is simple, the process is mild, the energy consumption is low, it is suitable for industrial production, and the reverse extractant can be water, which is safe and environmentally friendly, greatly reducing the usage amount of acids and alkalis.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) In the present invention, by designing the composition of the succinic acid extractant, and further through the synergistic effect of the complex with a specific structure and a specific co-solvent, through complex extraction, the extraction effect of the extractant on the high-concentration succinic acid crystallization mother liquor is improved, and the forward extraction yield and the reverse extraction yield in the extraction process of the succinic acid crystallization mother liquor are balanced. The forward extraction yield ≥ 98.12%, the reverse extraction yield ≥ 98.22%, and the difference between the forward extraction yield and the reverse extraction yield ≤ 0.5%. After extraction, the total yield of succinic acid is 96.37-99.12%, and the purity of succinic acid is 99.58-99.85%.

[0060] (2) In the present invention, by using a specific extractant, the extraction process of succinic acid is simple, the process is mild, the energy consumption is low, it is suitable for industrial production, and the reverse extractant can be water, which is safe and environmentally friendly, greatly reducing the usage amount of acids and alkalis.

[0061] (3) In the present invention, by using a specific extractant, succinic acid with high yield and high purity is obtained, and at the same time, the concentration of inorganic salt ions in the succinic acid crystallization mother liquor is reduced. Before extraction, in the succinic acid crystallization mother liquor, C(Na + ) is 1000 - 2000 ppm, C(Cl - ) is 100 - 500 ppm, C(SO4 2- ) is 100 - 500 ppm, C(PO4 3- ) is 200 - 1000 ppm, C(Fe 2+ ) is 100 - 1000 ppm. After extraction, in the solution, C(Na + ) is 18 - 35 ppm, C(Cl - ) is 8 - 13 ppm, C(SO4 2- ) is 55 - 99 ppm, C(PO4 3- ) is 66 - 112 ppm, C(Fe 2+ ) is 3 - 9 ppm. Detailed implementation manners

[0062] For the convenience of understanding the present invention, the following examples are listed. Those skilled in the art should understand that the said examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0063] Some component descriptions in the examples and comparative examples are as follows:

[0064] Table 1

[0065]

[0066]

[0067] Examples 1 - 11 and Comparative Examples 1 - 3

[0068] Examples 1 - 11 and Comparative Examples 1 - 3 respectively provide a method for complex extraction of succinic acid crystallization mother liquor, which specifically includes the following steps:

[0069] (1) Normal-phase extraction: Mix the succinic acid crystallization mother liquor with a normal-phase extractant according to a certain volume ratio (the specific selection and volume ratio of the normal-phase extractant are shown in Tables 2 - 4 below), and perform cross-flow extraction (the number of stages is 4 stages) at 50°C to obtain a succinic acid-loaded organic phase;

[0070] (2) Back extraction: Mix the succinic acid-loaded organic phase obtained in step (1) with the back extractant at a volume ratio of 1:4, and perform cross-flow extraction (5 stages) at 60 °C to obtain a succinic acid product phase and an extractant;

[0071] Evaporate and concentrate the succinic acid product phase, cool and crystallize, centrifuge, and dry to obtain succinic acid crystals;

[0072] Evaporate the extractant to obtain a regenerated extractant, which can be repeatedly used as a forward extractant for the complex extraction of succinic acid.

[0073] Table 2

[0074]

[0075]

[0076] Table 3

[0077]

[0078] Table 4

[0079]

[0080] The total recovery rate and purity of the succinic acid crystallization mother liquor used in the above examples and comparative examples and the succinic acid crystals obtained after complex extraction of the succinic acid crystallization mother liquor were tested as follows:

[0081] In the following text, test sample 1 is the succinic acid crystallization mother liquor used in the above examples and comparative examples, and test sample 2 is a succinic acid solution prepared by adding water to the succinic acid crystals obtained in the above examples and comparative examples (the concentration of succinic acid in the prepared succinic acid solution is the same as the concentration of succinic acid in the corresponding succinic acid crystallization mother liquor used in the examples and comparative examples).

[0082] (1) Detect the concentration of succinic acid in the test sample by HPLC

[0083] Use a Bio-RAD 442864 chromatographic column, with 5 mmol / L H2SO4 as the mobile phase, a flow rate of 0.5 mL / min, a column temperature of 35 °C, a detector temperature of 35 °C, a wavelength of 210 nm, and an injection volume of 20 μL for test solution 1 and test solution 2.

[0084] (2) Detect the inorganic salt content

[0085] Na + : ① Calibrate the sodium meter using standard sodium solutions with known concentrations (concentrations are 0.1 mol / L, 0.01 mol / L, 0.001 mol / L, 0.0001 mol / L) respectively;

[0086] ② Immerse the sodium meter and the reference electrode into the diluted sample to be tested 1 or sample to be tested 2, ensure that the sensitive part of the electrode is submerged, and gently stir to avoid generating bubbles or damaging the electrode;

[0087] ③ Record the reading after waiting for the potential to stabilize;

[0088] ④ Calculate the sodium ion concentration in the sample according to the calibration curve or calibration equation.

[0089] Cl - : ① 25% nitric acid solution: Measure 30.8 mL of concentrated nitric acid with a measuring cylinder and transfer it to a 100 mL volumetric flask, add deionized water to dilute to the scale, and shake well;

[0090] ② 17 g / L silver nitrate solution: Weigh 1.7 g of silver nitrate in a beaker, dissolve it with an appropriate amount of water, then transfer it to a 100 mL brown volumetric flask, add deionized water to dilute to the scale, and shake well;

[0091] ③ 0.01 mg / mL chloride (Cl) standard solution: Weigh 0.165 g of sodium chloride dried to constant weight, dissolve it in water, transfer it to a 100 mL volumetric flask, add deionized water to dilute to the scale, and shake well;

[0092] ④ Add 0.5, 1, 2, 3, 5, 10 mL of 0.01 mg / mL chloride (Cl) standard solution to six 25 mL colorimetric tubes respectively, then add 1 mL of 25% nitric acid solution and 1 mL of 17 g / L silver nitrate solution to each colorimetric tube, dilute to the scale with anhydrous ethanol, and shake well to prepare six standard turbidimetric solutions with proportional concentrations;

[0093] ⑤ Take 10 mL of sample to be tested 1 and sample to be tested 2 in 25 mL colorimetric tubes respectively, add 1 mL of 25% nitric acid solution and 1 mL of 17 g / L silver nitrate solution respectively, dilute to the scale with anhydrous ethanol, and shake well;

[0094] ⑥ Compare the sample solution with the standard turbidimetric solutions, and visually determine the range of chloride content in the sample.

[0095] SO4 2- : In a hydrochloric acid medium, barium ions react with sulfate ions to form insoluble barium sulfate. Barium sulfate is in a suspended state within a certain time, making the solution turbid. The determination of sulfate in industrial succinic acid adopts the visual turbidimetric method:

[0096] ① 95% ethanol solution: Measure 475 mL of anhydrous ethanol with a measuring cylinder and transfer it to a 500 mL volumetric flask, add ionic water to dilute to the scale, and shake well;

[0097] ② 20% hydrochloric acid solution: Measure 25.2 mL of concentrated hydrochloric acid with a measuring cylinder and transfer it to a 50 mL volumetric flask, add ionic water to dilute to the scale, and shake well;

[0098] ③ 250 g / L barium chloride solution: Weigh 62.5000 ± 0.0030 g of barium chloride into a 250 mL volumetric flask, add deionized water to dilute to the mark, and shake well;

[0099] ④ 0.1 mg / mL sulfate standard solution: Accurately weigh 0.1480 ± 0.0010 g of anhydrous sodium sulfate after drying, dissolve it in water, transfer it into a 100 ml volumetric flask, add deionized water to dilute to the mark, and shake well.

[0100] ⑤ Add 0.5, 1, 2, 3, 5 mL of 0.1 mg / mL sulfate standard solution to six 25 mL colorimetric tubes respectively. Then add 5 mL of 95% ethanol solution, 1 mL of 20% hydrochloric acid solution and 3 mL of 250 g / L barium chloride solution to each colorimetric tube, dilute to the mark with water, and shake well to prepare 5 standard turbidity solutions with proportional concentrations.

[0101] ⑥ Take 10 mL of test sample 1 and test sample 2 into 25 mL colorimetric tubes respectively, add 5 mL of 95% ethanol solution, 1 mL of 20% hydrochloric acid solution and 3 mL of 250 g / L barium chloride solution, dilute to the mark with deionized water, and shake well;

[0102] ⑦ Compare the sample solution with the standard turbidity solutions, and visually determine the range of sulfate content in the sample.

[0103] PO4 3- :

[0104] ① 10% ascorbic acid solution: Dissolve 10 g of ascorbic acid in 100 mL of water, make up the volume and reserve for use;

[0105] ② Molybdate solution: Weigh 13 g of ammonium molybdate into a beaker, add 100 mL of water to dissolve; Weigh 0.35 g of potassium antimony tartrate oxide, add 100 mL of water to dissolve; Slowly add the ammonium molybdate solution to the beaker containing 300 mL of sulfuric acid solution with stirring, then add the potassium antimony tartrate oxide solution and mix well. Transfer the mixed solution to a brown glass bottle and store it in a cool place;

[0106] ③ Phosphate stock solution: Dry potassium dihydrogen phosphate at 100 °C for 2 hours, place it in a desiccator and let it stand overnight; Weigh 0.217 g of potassium dihydrogen phosphate, dissolve it in water and transfer it to a 1000 mL volumetric flask, add 5 mL of sulfuric acid solution, make up the volume, and the phosphorus concentration in this solution is 50 μg / mL.

[0107] ④ Phosphate standard solution: Measure 10 mL of the phosphate stock solution into a 250 mL volumetric flask, add water to make up the volume. The phosphorus concentration in this solution is 2 μg / mL.

[0108] ⑤ Preparation of standard curve: Pipette 0 mL, 0.5 mL, 1.0 mL, 3.0 mL, 5.0 mL, 10.0 mL, and 15.0 mL of phosphate standard stock solution accurately into 50-mL stoppered colorimetric tubes respectively, add water to the calibration line, add 1 mL of 10% ascorbic acid solution to each colorimetric tube, mix well, add 2 mL of molybdate solution after 30 seconds and mix thoroughly, let stand for 15 minutes, use a 10-mm colorimetric cell, at a wavelength of 700 nm, with the zero-concentration solution as the reference, measure the absorbance;

[0109] ⑥ Determination of samples: Pipette 0.1 mL of test sample 1 and test sample 2 into colorimetric tubes respectively, dilute with water to the calibration line, add 1 mL of 10% ascorbic acid solution to the colorimetric tubes, mix well, add 2 mL of molybdate solution after 30 seconds and mix thoroughly, let stand for 15 minutes, use a 10-mm colorimetric cell, at a wavelength of 700 nm, with the zero-concentration solution as the reference, measure the absorbance, and find out the phosphorus content from the standard curve.

[0110] Fe 2+ : Measure 100 mL of test solution 1 and test solution 2, place them in 500-mL volumetric flasks respectively, make up the volume with carbon dioxide-free water, pipette 10 mL and transfer it into a 25-mL colorimetric tube as the sample solution, and conduct the rest according to the provisions of the spectrophotometry method in GB / T9739-2006.

[0111] The specific test data are shown in Table 5 below:

[0112] Table 5

[0113]

[0114] Table 6

[0115]

[0116]

[0117] As can be seen from the above, in the present invention, by designing the composition of the succinic acid extractant, and further through the synergistic effect of a complex with a specific structure and a specific cosolvent, through complex extraction, the extraction effect of the extractant on the high-concentration succinic acid crystallization mother liquor is improved, and the forward extraction yield and the reverse extraction yield in the extraction process of the succinic acid crystallization mother liquor are balanced. The forward extraction yield ≥ 97.43%, the reverse extraction yield ≥ 96.87%, and the difference between the forward extraction yield and the reverse extraction yield ≤ 0.78%. After extraction, the total yield of succinic acid is 90.15 - 99.19%, and the purity of succinic acid is 98.97 - 99.85%. Moreover, in the present invention, by using a specific extractant, the extraction process of succinic acid is simple, the process is mild, the energy consumption is low, it is suitable for industrial production, and the reverse extractant can be water, which is safe and environmentally friendly, and greatly reduces the usage amount of acids and alkalis.

[0118] Meanwhile, in the present invention, by using a specific extractant, succinic acid with a high yield and high purity is obtained, and at the same time, the concentration of inorganic salt ions in the succinic acid crystallization mother liquor is reduced. Before extraction, in the succinic acid crystallization mother liquor, C(Na + ) is 1000 - 2000 ppm, C(Cl - ) is 100 - 500 ppm, C(SO4 2- ) is 100 - 500 ppm, C(PO4 3- ) is 200 - 1000 ppm, C(Fe 2+ ) is 100 - 1000 ppm. After extraction, in the solution, C(Na + ) is 18 - 35 ppm, C(Cl - ) is 8 - 13 ppm, C(SO4 2- ) is 55 - 99 ppm, C(PO4 3- ) is 66 - 112 ppm, C(Fe 2+ ) is 3 - 9 ppm.

[0119] As can be seen from the content of Examples 1 - 9, in the present invention, through the synergistic effect of a specific complexing agent and a specific cosolvent, the extraction effect of the extractant on the high-concentration succinic acid crystallization mother liquor is further improved, and the forward extraction yield and the reverse extraction yield in the extraction process of the succinic acid crystallization mother liquor are balanced.

[0120] As can be seen from the content of Example 1 and Examples 10 - 12, in the present invention, by controlling the volume ratio of the complexing agent and the specific cosolvent within a specific range, the extraction effect of the extractant on the high-concentration succinic acid crystallization mother liquor is further improved.

[0121] As can be seen from the content of Example 1 and Comparative Examples 1-3, through the synergistic effect of the complexing agent and the cosolvent, the present invention further improves the extraction effect of the extractant on the high-concentration succinic acid crystallization mother liquor and balances the positive extraction yield and the reverse extraction yield in the extraction process of the succinic acid crystallization mother liquor.

[0122] In summary, in the present invention, by designing the composition of the succinic acid extractant, further through the synergistic effect of the complex with a specific structure and a specific cosolvent, through complex extraction, the extraction effect of the extractant on the high-concentration succinic acid crystallization mother liquor is improved, and the positive extraction yield and the reverse extraction yield in the extraction process of the succinic acid crystallization mother liquor are balanced.

[0123] The applicant declares that the present invention uses the above examples to illustrate the detailed process flow of the present invention, but the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A succinic acid extractant, characterized in that, The succinic acid extractant is composed of a complexing agent and a cosolvent shown by the following formula I; wherein, R1 represents an ester group with 1 - 10 carbon atoms; R2 and R3 each independently represent any one of an alkyl group with 1 - 10 carbon atoms, an ester group with 1 - 10 carbon atoms or a hydroxyl group; The cosolvent is an alcohol solvent containing 7 - 10 carbon atoms.

2. The succinic acid extractant according to claim 1, wherein, The R1 represents any one of an isooctyl ester group, a dimethylheptyl ester group or a 2 - ethylhexyl ester group.

3. The succinic acid extractant according to claim 1, characterized in that, The R2 and R3 each independently represent any one of a methyl group, an ethyl group, a propyl group, a hydroxyl group, an isooctyl ester group, a dimethylheptyl ester group or a 2 - ethylhexyl ester group.

4. The succinic acid extractant according to claim 1, characterized in that, The complexing agent is selected from any one or a combination of at least two of diisooctyl phosphate, dimethylheptyl methylphosphonate or 2 - ethylhexyl 2 - ethylhexylphosphate.

5. The succinic acid extractant according to claim 1, characterized in that, The cosolvent is selected from any one or a combination of at least two of n - heptanol, isooctanol, n - nonanol or n - decanol.

6. The succinic acid extractant according to claim 1, characterized in that, The volume ratio of the complexing agent to the cosolvent is 1:(0.1 - 10).

7. A method for complex extraction of succinic acid crystallization mother liquor, characterized in that, The method includes the following steps: (1) Normal - phase extraction: Mix the succinic acid crystallization mother liquor with a normal - phase extractant, and extract to obtain a succinic acid - loaded organic phase; (2) Reverse extraction: Mix the succinic acid - loaded organic phase obtained in step (1) with a reverse extractant, and extract to obtain succinic acid crystals and a normal - phase extractant; The normal - phase extractant includes the succinic acid extractant as described in any one of claims 1 - 6.

8. The method according to claim 7, characterized in that, The concentration of succinic acid in the succinic acid crystallization mother liquor is 10 - 110 g / L, preferably 60 - 110 g / L.

9. The method according to claim 7, wherein The volume ratio of the succinic acid crystallization mother liquor to the normal - phase extractant is 1:(1 - 5).

10. The method according to claim 7, characterized in that, The reverse extractant includes water.

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