Method for extracting and refining long carbon chain dicarboxylic acid produced by biological fermentation method

Abstract

The invention belongs to the technical field of material extraction and refining, and particularly relates to a method for extracting and refining long carbon chain dibasic acid produced by a biological fermentation method, which comprises the following steps: 1) adding an acidic material into long carbon chain dibasic acid fermentation liquor obtained by the biological fermentation method to adjust the pH value to 5.5-6.5, reacting, separating out solid, and separating to obtain a precipitate; 2) adding the precipitate into water, adding an alkaline substance to adjust the pH value to be greater than or equal to 7.8, and dissolving the precipitate to obtain a treatment solution; (3) adding an acidic material into the treating fluid to adjust the pH value to be less than or equal to 4.5, reacting, separating out a solid, and separating to obtain a long carbon chain dibasic acid crude product, and (4) mixing the long carbon chain dibasic acid crude product with an acid solution, and then carrying out melt crystallization to obtain the long carbon chain dibasic acid, so that the yield and the purity are improved, and the chromatic value is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of material extraction and purification, and specifically relates to a method for extracting and refining a long carbon chain dibasic acid produced by a biological fermentation method. Background Art

[0002] Long-chain dibasic acid refers to a straight-chain aliphatic dibasic acid containing more than 10 carbon atoms in the carbon chain, and its general structural formula is HOOC-(CH2) n -COOH (n=8~16), abbreviated as DC10~DC18. Long carbon chain dibasic acids not only do not exist in nature, but their synthesis mainly depends on chemical synthesis and biological fermentation.

[0003] With the rapid development of electronics, medical, automobile and other industries, the demand for long-chain dibasic acids continues to rise. Due to its economic and environmental advantages, biological fermentation has gradually replaced traditional chemical synthesis and become the leading technology in the market.

[0004] After the long-chain dibasic acid is prepared by the biological fermentation method, it contains a large amount of impurities such as bacteria and proteins, which need to be extracted and purified.

[0005] "Progress in Extraction Technology of Mixed Dibasic Acids from Long-Chain Dibasic Acid Heavy Components" (Yang Chen et al., Chemical Industry Progress, Vol. 39, No. 10, 2020) discloses that due to differences in fermentation target products and extraction and refining processes, the composition of the heavy components is not fixed. The main component categories include: ① mixed long-chain dibasic acids, with a content ranging from 50% to 70%, and the number of dibasic acid carbon chains ranging from 9 to 18; ② monobasic acids and unsaturated acids, with a content of 10% to 25%; ③ inorganic salts, pigments, cell components and metabolic by-products, etc., with a content of 10% to 30%.

[0006] A variety of different extraction methods are also disclosed. The aqueous phase salt-forming-acidification crystallization method is simple to operate and does not require a solvent, but consumes acid and alkali and produces a large amount of salt, which needs to be treated; the organic solvent crystallization method can adopt the method of concentration followed by cooling and crystallization, which is highly compatible with the main production line process and requires little equipment modification work; the extraction method requires the use of a solvent, and some special solvents can separate impurities such as pigments, but the separation effect of the solvent needs to be considered; the chromatographic separation method is difficult to achieve a high degree of separation, the chromatographic column operation is complicated, and it is not suitable for large-scale production; the key to the esterification separation method is the need to connect the esterification product with the market.

[0007] The core principle of this method is based on acid-base neutralization reaction. The main steps are to react the heavy component with a soluble base, and the acid in the heavy component generates the corresponding salt. The obtained salt is adjusted to an aqueous solution of a certain concentration, and then removed by pretreatment such as decolorization and filtration to remove impurities. Then, acid is added to adjust the pH, and the salt is converted into an acid precipitate to obtain a mixed acid. The aqueous phase method is simple to operate, the conditions are relatively mild, and no solvent is required. However, it consumes acid and alkali, produces more salt, and needs to be treated. Practice has proved that the purity, appearance color and crystal size of the product obtained by the aqueous phase method of refining dibasic acid are worse than those of the organic solvent method. At the same time, the product color stability is poor, which leads to an increase in the unqualified rate of downstream products. Therefore, in order to obtain high-purity long-chain dibasic acids, the aqueous phase method must be further improved. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a method for extracting and refining long-carbon-chain dibasic acid produced by a biological fermentation method, thereby improving the yield and purity and reducing the chromaticity value.

[0009] The embodiment of the present invention provides a method for extracting and refining a long carbon chain dibasic acid produced by a biological fermentation method, comprising the following steps: 1) adding an acidic substance to the long-chain dibasic acid fermentation broth obtained by the biological fermentation method to adjust the pH value to 5.5-6.5, causing the broth to react and precipitate solids, and separating the solids to obtain a precipitate; 2) adding the precipitate into water, adding alkaline substances to adjust the pH value to ≥ 7.8, dissolving the precipitate, and obtaining a treated liquid; 3) adding an acidic substance to the treatment liquid to adjust the pH value to ≤4.5, causing the liquid to react and precipitate a solid, and separating the solid to obtain a crude long-chain dibasic acid; 4) Mixing the crude long-chain dibasic acid with an acid solution, and then melting and crystallizing the mixture to obtain a long-chain dibasic acid.

[0010] Preferably, in step 1) or / and step 3), the acidic substance comprises chloroacetic acid.

[0011] Preferably, in step 1) or / and step 3), the acidic substance further comprises at least one of bisulfate, sulfuric acid, oxalic acid and citric acid.

[0012] Preferably, the acid solution in step 4) is an oxalic acid aqueous solution, a chloroacetic acid aqueous solution or a citric acid aqueous solution, and the mass concentration of the acid is 1-5.5%.

[0013] Preferably, in step 1), an acidic substance is added to adjust the pH value to 5.8-6.2.

[0014] Preferably, in step 1), the pH of the long-chain dibasic acid fermentation broth is first adjusted to above 7.8 with an alkali, and then an acidic substance is added to adjust the pH value to 5.5-6.5. Preferably, in step 2) an alkaline substance is added to adjust the pH value to 7.8-12; and in step 3) an acidic substance is added to adjust the pH value to 1.0-4.5.

[0015] Preferably, the long-chain dibasic acid is a straight-chain aliphatic dibasic acid containing 10 to 18 carbon atoms; the long-chain dibasic acid fermentation broth is obtained from alkanes by biological fermentation, and sodium salt or potassium salt is added to the fermentation medium.

[0016] Preferably, step 1) comprises: heating the long-chain dibasic acid fermentation broth to 45-65° C., adding an acidic substance to adjust the pH value; then cooling to 30-45° C., stirring for 1-1.5 hours, and performing solid-liquid separation to obtain a precipitate.

[0017] Preferably, step 2) comprises: adding alkaline substances at 45-65° C. to adjust the pH value, and then using activated carbon for decolorization and filtering (the number of times of adding activated carbon for decolorization is 2 times, and the weight of activated carbon added is 5-50% of the weight of the salt-forming solid).

[0018] Preferably, step 3) comprises: adding an acidic substance at 45-65° C. to adjust the pH value (preferably, the acidic substance comprises chloroacetic acid, the weight of the chloroacetic acid is at least 50% of the total weight of the acidic substance, and the pH value is adjusted to 3.0-3.5 by adding the acidic substance), stirring for 1-1.5 hours, and filtering.

[0019] Preferably, the melt crystallization in step 4) is carried out by raising the temperature to 105-111° C., maintaining the temperature, and then cooling the crystallization (preferably gradient cooling crystallization).

[0020] Preferably, in step 1), the weight of the chloroacetic acid is at least 50% of the total weight of the acidic substance. In step 2), the alkaline substance is at least one of sodium hydroxide, potassium hydroxide, potassium carbonate and sodium carbonate.

[0021] The gradient cooling crystallization of the present invention is preferably cooled to 95-85°C, kept warm; 85-75°C, kept warm; 75-65°C, kept warm; 65-55°C, kept warm. More preferably, it is cooled to 90°C, kept warm for 0.5h; 80°C, kept warm for 0.5h; 70°C, kept warm for 0.5h; 60°C, kept warm for 0.5h.

[0022] The beneficial effect of the present invention is that the present invention first adds acid to the fermentation liquid to adjust the pH value to weak acidity, that is, 5.5-6.5. At this pH, the solid solubility of the long-chain dibasic acid monosodium (or potassium) is the lowest, and the long-chain dibasic acid disodium (or potassium) in the fermentation liquid is converted into the long-chain dibasic acid monosodium (or potassium) salt. At this time, the acidity of the solution is not strong, so the protein, pigment, etc. in the mother liquor will not precipitate, and will be separated along with the mother liquor. After filtration, most of the protein, pigment, and acid-soluble substances in the mother liquor system can be removed, thereby greatly reducing the content of impurities. Compared with the method of directly adding acid to adjust the pH value to strong acidity, the present invention can greatly reduce the content of impurities, especially chromaticity, and improve product color stability and product quality.

[0023] When the present invention adds acid to adjust the pH value, the added acid is chloroacetic acid. The inventors have found that, compared with other acids, such as sulfuric acid, chloroacetic acid has better effects of dissolving protein and removing impurities such as protein, and can greatly improve the color stability of the product, while improving the product purity and the extraction and refining effect. Compared with the method of adding conventional sulfuric acid and a larger amount of activated carbon for decolorization, the present invention adds chloroacetic acid, which has lower chroma, better color stability and higher purity.

[0024] Refining by high temperature melt crystallization can further improve product purity, reduce chroma, and improve color stability. In the crystallization process of the present invention, acid is also added, and the addition of acid changes the state of the system, reduces the total amount of waste water, reduces the impurities of crystallization, reduces chroma and improves color stability. The acid of this step is preferably oxalic acid, chloroacetic acid or citric acid, more preferably oxalic acid or chloroacetic acid, which can more significantly reduce impurities and chroma relative to other acids, and improve product color stability.

[0025] The invention is simple to operate. Through a simple alkali dissolution and acid precipitation process, coupled with activated carbon decolorization and adsorption, the purity of decacarbonic acid is greater than 99.4%, the chromaticity value is 0-5; the purity of dodecacarbonic acid is greater than 99.6%, the chromaticity value is 0-5; the purity of tridecacarbonic acid is greater than 99.0%, the chromaticity value is 0-5, and the white crystal or powder with good color stability can be obtained. The invention has a short production cycle, simple equipment, and meets the requirements of industrialized and industrialized large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention.

[0027] Figure 2 This is a gas chromatogram of the finished dodecanedioic acid product of Example 1 of the present invention.

[0028] Figure 3 This is a gas chromatogram of the finished product of tridecanedioic acid in Example 2 of the present invention.

[0029] Figure 4 This is a gas chromatogram of the finished dodecanedioic acid product of Example 3 of the present invention.

[0030] Figure 5 This is a photo of the finished product of dodecanedioic acid in Example 1 of the present invention.

[0031] Figure 6 This is a photo of the finished product of dodecanedioic acid of Comparative Example 1 of the present invention.

[0032] Figure 7 This is a photo of the finished product of dodecanedioic acid of Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0033] The long carbon chain dibasic acid of the present invention refers to a straight chain aliphatic dibasic acid containing more than 10 carbon atoms in the carbon chain, preferably containing 10 to 18 carbon atoms, more preferably 10 to 15 carbon atoms, such as decacarbon dibasic acid, dodecacarbon dibasic acid, tridecacarbon dibasic acid, etc.

[0034] The long carbon chain dibasic acid fermentation broth used in the present invention is obtained by a biological fermentation method. The present invention has no limitation on the specific fermentation method. For example, the corresponding alkane is fermented by using a dibasic acid bacteria to obtain a long carbon chain dibasic acid fermentation broth. The dibasic acid bacteria is selected from one of the genera Candida, Cryptococcus, Endosporium, Hansenula, Pichia, Rhodotorula, Torulopsis or Trichosporon.

[0035] Sodium salts (such as sodium chloride, sodium sulfate) or potassium salts (such as potassium dihydrogen phosphate) are added to the fermentation medium, and sodium salts are also present in the medium components such as corn steep liquor and yeast extract. The sodium (or potassium) ions therein are converted into the form of disodium (or potassium) or monosodium (or potassium) of long-chain dibasic acid during the subsequent refining process of the present invention. For example, the fermentation medium contains 0.5-1.5 g / L of sodium chloride, 1-2 g / L of yeast extract, or 3-8 g / L of potassium dihydrogen phosphate.

[0036] The pH of the long-chain dibasic acid fermentation broth is about 7, which is slightly different according to different fermentation methods and fermentation conditions. The presence of the normal long-chain dibasic acid is generally a mixture containing disodium (or potassium) of normal long-chain dibasic acid, monosodium (or potassium) of dibasic acid, and part of the normal long-chain dibasic acid. The fermentation broth contains a large amount of protein and pigment, which affects the purity, chromaticity and color stability (chromaticity changes over time) of the product. The extraction and purification method of the present invention includes the following stages (its process flow is as follows Figure 1 shown): (1) Acidification is added to the fermentation broth to adjust the pH value to 5.5-6.5, more preferably 5.8-6.2, so that the disodium (or potassium) of the normal long-chain dibasic acid therein can be converted into monosodium (or potassium) of the dibasic acid. The resulting precipitate is monosodium (or potassium) of the dibasic acid or a mixture of monosodium (or potassium) of the dibasic acid and a small amount of the normal long-chain dibasic acid.

[0037] The acid can be sodium bisulfate (potassium), sulfuric acid, oxalic acid, citric acid, trifluoroacetic acid, chloroacetic acid, chloroacetic acid + sodium bisulfate (potassium), chloroacetic acid + sulfuric acid, chloroacetic acid + oxalic acid, chloroacetic acid + citric acid, etc., preferably chloroacetic acid. Chloroacetic acid can also be used to adjust the pH to 6.3-6.5 first, and then other acids are used to adjust to the target pH. Chloroacetic acid can greatly improve the color stability of the product compared to other acids (such as sulfuric acid and trifluoroacetic acid). When adjusting the pH in this step, chloroacetic acid is significantly better than oxalic acid or citric acid, and can better remove impurities such as protein and improve color stability. Experiments show that chloroacetic acid is better than sulfuric acid + activated carbon (using sulfuric acid to adjust the pH and only using activated carbon for decolorization) in reducing chroma and improving color stability. The decolorization effect is also better than that of hydrogen peroxide.

[0038] If the long-chain dibasic acid fermentation broth is first adjusted to a pH of 7.8 or above with an alkali (such as sodium hydroxide), all the products will be converted into disodium (or potassium) salts, and a large amount of alkaline proteins will also dissolve, providing favorable conditions for subsequent refining. At this time, the fermentation broth is acidified to adjust the pH value to 5.5-6.5, more preferably 5.8-6.2, to obtain monosodium (or potassium) dibasic acid.

[0039] The pH value adjustment process in this step can be carried out at 45-65°C, and then stirred at 30-45°C for 1-1.5 hours. The monosodium (or potassium) dibasic acid solid or a mixture of monosodium (or potassium) dibasic acid and a small amount of normal long carbon chain dibasic acid can be obtained by solid-liquid separation methods such as filtration and centrifugation.

[0040] (2) Add alkaline substances to adjust the pH value to 7.8-12, preferably 8.5-9.7. Both monosodium (or potassium) dibasic acid and dibasic acid will be converted into disodium (or potassium) dibasic acid.

[0041] However, if the pH is adjusted directly to above 7.8 without going through the step of "adjusting the pH to 5.5-6.5", the strong alkalinity will dissolve a large amount of protein. When the pH is then adjusted to strong acidity (pH=1.0-4.5), the protein will precipitate out together with the dibasic acid and cannot be removed, resulting in a very high color, a light yellow product, and a lower purity.

[0042] The alkaline substance may be at least one of sodium hydroxide, potassium hydroxide, potassium carbonate and sodium carbonate.

[0043] The pH value adjustment process in this step can be carried out at 45-65°C until it is completely dissolved, and then activated carbon can be used for decolorization at 45-65°C, preferably decolorization 1-2 times, and then filtered to obtain a dibasic acid disodium (or potassium) solution. The weight of activated carbon added is preferably 5-50% of the weight of the precipitate (monosodium / potassium salt wet product) in step 1).

[0044] (3) adding an acidic substance to adjust the pH value to 1.0-4.5, preferably 3.0-3.5, so that the long carbon chain dibasic acid is precipitated to obtain a crude dibasic acid product, which is then refined by melt crystallization to obtain a finished dibasic acid product.

[0045] The acidic substance is preferably chloroacetic acid, and may also include one or more of sodium (potassium) hydrogen sulfate, sulfuric acid, oxalic acid, and citric acid. Chloroacetic acid may be used directly to adjust the target pH, or chloroacetic acid or other acids may be used to adjust the pH to 5.9-6.2, and then other acids or chloroacetic acid may be used to adjust the target pH.

[0046] The pH value adjustment process in this step can be carried out at 45-65°C, followed by stirring at 45-65°C for 1-1.5h, filtering, and purifying the filter cake by beating with water at 45-65°C, and obtaining a crude diacid by solid-liquid separation methods such as filtration and centrifugation.

[0047] Preferably, an acid solution is added to the crude diacid, followed by melt crystallization, centrifugation, and drying to obtain a finished dibasic acid product. The acid solution is preferably an aqueous solution of oxalic acid or chloroacetic acid, and the concentration is preferably 1-5.5%, more preferably 1-3.5%. Melt crystallization is to first heat the temperature to 105-111°C to melt the product, and then cool it down to crystallize.

[0048] The melt crystallization in this step can remove the residual trace protein and improve the color stability. Oxalic acid or chloroacetic acid can achieve better results. However, if there are a lot of impurities such as protein, chloroacetic acid can achieve better results in step (1), while oxalic acid has a poor effect.

[0049] If sulfuric acid is used to adjust the pH throughout the process, sodium sulfate salt will cause the product ash (ignition residue) value to be very high, affecting the product purity, chromaticity value and color stability. During the high-temperature melting crystallization process, all sodium sulfate is released into the water layer, and the product forms a crystal form, which helps to improve the product purity, reduce the chromaticity and improve the color stability.

[0050] The chloroacetic acid described in the embodiments of the present invention refers to monochloroacetic acid.

[0051] Example 1 A method for extracting and refining a long carbon chain dibasic acid produced by a biological fermentation method comprises the following steps: 1. Referring to the fermentation method of Example 1 of patent document CN103805643B, a dodecanedioic acid fermentation broth was obtained, and the acid content was 190 g / L (this content was the total content of free dibasic acid and its salt).

[0052] 2. Take 1L of the above-mentioned dodecanedioic acid fermentation broth and heat it to 58°C, slowly add 40.5g of chloroacetic acid, and adjust the system pH to 6.2.

[0053] 3. Cool the system to 40°C, keep stirring for 1 hour, filter, and rinse the filter cake with 0.5L purified water to obtain 300g of wet product of monosodium (or potassium) dodecanedioic acid.

[0054] 4. Add 300g of wet monosodium (or potassium) dodecanedioic acid salt into 1.5L of purified water, heat to 55°C and stir evenly, use 65ml of liquid alkali (mass concentration 30%) to slowly adjust the pH of the system to 9.5 until the system is completely dissolved.

[0055] 5. Add 17 g of activated carbon to the system, decolorize for 20 min, filter hot, and rinse the filter cake with 100 ml of purified water.

[0056] 6. Keep the filtrate at 55°C, add 6 g of activated carbon again, decolorize for 25 min, filter hot, and rinse the filter cake with 100 ml of purified water.

[0057] 7. Keep the filtrate at 55°C, slowly add 50g of chloroacetic acid to adjust the pH to 6.1, and then slowly add 40g of sodium bisulfate to adjust the pH to 3.5.

[0058] 8. Keep the system at 55°C, stir for 1 hour, filter, and rinse the filter cake with 200 ml of water.

[0059] 9. Add 500 ml of purified water to the filter cake, heat to 55°C, stir for 2 hours, filter, rinse the filter cake with 100 ml of water, and obtain 280 g of wet dodecanedioic acid.

[0060] 10. Add 280g wet dodecanedioic acid, 20g oxalic acid and 1.5L purified water to the crystallization kettle, stir for 20min, heat to (95-100)℃ with steam, open the exhaust valve to vent the pressure in the tank, and close the exhaust valve of the crystallization kettle after the pressure in the tank is vented. When the temperature of the crystallization kettle rises to (105-111)℃ and the system is in a molten transparent state, close the steam valve of the crystallization kettle to stop heating. Keep the temperature and pressure for 30min, open the exhaust valve to start natural cooling, cool to 95℃, and then slowly pass condensed water to cool. The gradient cooling process is controlled for 2.5h (95-85℃ 0.5h, 85-75℃ 0.5h, 75-65℃ 0.5h, 65-55℃ 1h).

[0061] 11. Filter, rinse with 200 ml of 50°C hot purified water, and dry at 90°C. Obtain 171 g of finished dodecanedioic acid (appearance: bright white crystals, chromaticity value: 2). Mass yield: 90%.

[0062] Figure 2 This is the gas chromatogram of the finished dodecanedioic acid of this example. The retention time of dodecanedioic acid is 14.295, and the purity calculated by the peak area normalization method is 99.81%.

[0063] The photo of the product of Example 1 is as follows Figure 5 The color stability of its products is shown in Table 1 below.

[0064] Table 1 Chromaticity values ​​of the product of Example 1 at different temperatures and times

[0065] Example 2 A method for extracting and refining a long carbon chain dibasic acid produced by a biological fermentation method comprises the following steps: 1. Referring to the fermentation method of Example 2 of patent document CN103805643B, a tridecanedioic acid fermentation liquid was obtained, and the acid content was 200 g / L.

[0066] 2. Take 1L of the above-mentioned tridecanedioic acid fermentation broth and heat it to 60°C, slowly add 35g of chloroacetic acid, adjust the pH of the system to 6.5, and then add 20ml of 65% sulfuric acid solution to adjust the pH to 5.9.

[0067] 3. Cool the system to 42°C, keep stirring for 1 hour, filter, and rinse the filter cake with 0.5L purified water to obtain 330g of wet product of monosodium (or potassium) tridecanedioic acid.

[0068] 4. Add 330g of wet monosodium (or potassium) tridecanedioic acid salt into 1.6L of purified water, heat to 55°C and stir evenly, and use 72ml of 32% potassium hydroxide solution to slowly adjust the pH of the system to 9.7 until the system is completely dissolved.

[0069] 5. Add 25 g of activated carbon to the system, decolorize for 25 min, filter hot, and rinse the filter cake with 100 ml of purified water.

[0070] 6. Keep the filtrate at 55°C, slowly add 53g of chloroacetic acid to adjust the pH to 6.3, and then slowly add 60ml of 70% sulfuric acid solution to adjust the pH to 3.0.

[0071] 7. Keep the system at 55°C and stir for 1 hour, filter, and rinse the filter cake with 150 ml of water.

[0072] 8. Add 600 ml of purified water to the filter cake, heat to 55°C, stir for 2 hours, filter, rinse the filter cake with 150 ml of water to obtain 300 g of wet tridecanedioic acid.

[0073] 9. Add 300g of wet tridecanedioic acid, 20g of chloroacetic acid and 2.0L of purified water to the crystallization kettle. Stir for 20 minutes and then heat to (95-100)℃ with steam. Open the exhaust valve to vent the pressure in the tank. After the pressure in the tank is vented, close the exhaust valve of the crystallization kettle. When the temperature of the crystallization kettle rises to (105-111)℃ and the system is in a molten transparent state, close the steam valve of the crystallization kettle to stop heating. Keep the temperature and pressure for 30 minutes, open the exhaust valve to start natural cooling, cool to 95℃, and then slowly pass condensed water to cool. The gradient cooling process is controlled for 2.5h (95-85℃ 0.5h, 85-75℃ 0.5h, 75-65℃ 0.5h, 65-55℃ 1h).

[0074] 10. Filter, rinse with 300 ml of 55°C hot purified water, and dry at 90°C. Obtain 179 g of tridecanedioic acid product (appearance: bright white crystals, chromaticity value: 3). Mass yield: 89.5%.

[0075] Figure 3 This is the gas chromatogram of the finished product of tridecanedioic acid in this example. The retention time of tridecanedioic acid is 14.33, and its purity is 99.21% calculated by the peak area normalization method.

[0076] Example 3 A method for extracting and refining a long carbon chain dibasic acid produced by a biological fermentation method comprises the following steps: 1. Referring to the fermentation method of Example 1 of patent document CN103805643B, a dodecanedioic acid fermentation broth was obtained with an acid content of 200 g / L.

[0077] 2. Take the above 1L dodecanedioic acid fermentation broth and heat it to 62°C, slowly add 250g sodium hydroxide solution (mass concentration 10%) to adjust the pH to about 8.5, stir for 1h, then add 66.5g chloroacetic acid to adjust the system pH to 6.1.

[0078] 3. Cool the system to 35°C, keep stirring for 1 hour, filter, and rinse the filter cake with 1L of purified water to obtain 320g of wet monosodium (or potassium) dodecanedioic acid salt.

[0079] 4. Add 320g of wet monosodium (or potassium) dodecanedioic acid salt into 1.6L of purified water, heat to 55°C and stir evenly, use 70ml of liquid alkali (mass concentration 30%) to slowly adjust the pH of the system to 9.7 until the system is completely dissolved.

[0080] 5. Add 20g of activated carbon to the system, decolorize for 25min, filter hot, and rinse the filter cake with 150ml of purified water.

[0081] 6. Keep the filtrate at 60°C, add 6.5 g of activated carbon again, decolorize for 25 min, filter hot, and rinse the filter cake with 150 ml of purified water.

[0082] 7. Keep the filtrate at 55°C, slowly add 50g of chloroacetic acid to adjust the pH to 6.1, and then slowly add 45g of sodium bisulfate to adjust the pH to 3.2.

[0083] 8. Keep the system at 55°C, stir for 1 hour, filter, and rinse the filter cake with 200 ml of water.

[0084] 9. Add 500 ml of purified water to the filter cake, heat to 55°C, stir for 2 hours, filter, rinse the filter cake with 100 ml of water, and obtain 290 g of wet dodecanedioic acid.

[0085] 10. Add 290g wet dodecanedioic acid, 20g oxalic acid and 1.5L purified water to the crystallization kettle. Stir for 20 minutes and heat to (95-100)℃ with steam. Open the exhaust valve to vent the pressure in the tank. After the pressure in the tank is vented, close the exhaust valve of the crystallization kettle. When the temperature of the crystallization kettle rises to (105-111)℃ and the system is in a molten transparent state, close the steam valve of the crystallization kettle to stop heating. Keep the temperature and pressure for 30 minutes, open the exhaust valve to start natural cooling, cool to 95℃, and then slowly pass condensed water to cool. The gradient cooling process is controlled for 2.5h (95-85℃ 0.5h, 85-75℃ 0.5h, 75-65℃ 0.5h, 65-55℃ 1h).

[0086] 11. Filter, rinse with 200 ml of 50°C hot purified water, and dry at 90°C. Obtain 175 g of finished dodecanedioic acid (appearance: bright white crystals, chromaticity value: 2). Mass yield: 87.5%.

[0087] Figure 4 This is the gas phase spectrum of the finished product of dodecanedioic acid in this example. The retention time of dodecanedioic acid is 14.295, and its purity is 99.48% calculated by the peak area normalization method.

[0088] Comparative Example 1 Compared with Example 1, the difference is that: Steps 2 and 3 are omitted, 1L of dodecanedioic acid fermentation broth is directly heated to 55°C, and 65ml of liquid alkali (mass concentration 30%) is used to slowly adjust the system pH to 9.5 until the system product is completely dissolved. Then, step 5 is performed.

[0089] The rest is the same as Example 1.

[0090] 180 g of finished dodecanedioic acid was obtained (appearance: light yellow crystals, chromaticity value: 45, unqualified). Yield: 94.7%, purity: 98.3%.

[0091] The photo of the product of Comparative Example 1 is as follows Figure 6 shown.

[0092] Comparative Example 2 Compared with Example 1, the difference is that step 2 is: 2. Take 1L of the above-mentioned dodecanedioic acid fermentation broth and heat it to 58°C, slowly add 40.5g of chloroacetic acid, adjust the pH of the system to 6.2, and then slowly add 103g of sodium bisulfate to adjust the pH to 3.5.

[0093] The rest is the same as Example 1.

[0094] 175 g of finished dodecanedioic acid (appearance: light yellow crystals, chromaticity value: 50) was obtained. Yield: 92.07%, purity: 98.4%.

[0095] Comparative Example 3 Compared with Example 1, the difference lies in step 2 and step 6, and step 2 is: 2. Take 1L of the above-mentioned dodecanedioic acid fermentation broth and heat it to 58°C, slowly add 89.5g of 30% sulfuric acid, and adjust the pH of the system to 6.2.

[0096] Step 6 is: keep the filtrate at 55°C, add 17g of activated carbon again, decolorize for 25min, filter hot, and rinse the filter cake with 100ml of purified water.

[0097] The rest is the same as Example 1.

[0098] 171 g of finished dodecanedioic acid (appearance: white crystals, chromaticity value: 16) was obtained. Yield: 90%, purity: 98.9%.

[0099] Comparative Example 4 Compared with Example 1, the difference is that step 10 is: 10. Add 280g wet dodecanedioic acid, 10g 30% sulfuric acid, and 1.5L purified water to the crystallization kettle. Stir for 20 minutes, then heat to (95-100)°C with steam, open the exhaust valve to vent the pressure in the tank, and close the exhaust valve of the crystallization kettle after the pressure in the tank is vented. When the temperature of the crystallization kettle rises to (105-111)°C and the system is in a molten transparent state, close the steam valve of the crystallization kettle to stop heating. Keep the temperature and pressure for 30 minutes, open the exhaust valve to start natural cooling, cool to 95°C, and then slowly cool with condensed water. The gradient cooling process is controlled for 2.5h (95-85°C 0.5h, 85-75°C 0.5h, 75-65°C 0.5h, 65-55°C 1h).

[0100] The rest is the same as Example 1.

[0101] 169 g of finished dodecanedioic acid (appearance: white crystals, chromaticity value: 8) were obtained. Yield: 88.9%, purity: 99.25%.

[0102] The photo of the product of Comparative Example 4 is as follows Figure 7The color stability of its products is shown in Table 2 below.

[0103] Table 2 Chromaticity values ​​of the product of Comparative Example 4 at different temperatures and times

[0104] Comparative Example 5 Compared with Example 1, the difference is that chloroacetic acid in steps 2 and 7 is replaced by sulfuric acid, and steps 10-11 are omitted. The wet product is dried, and the appearance is off-white powder, the chromaticity value is 40, the purity is 98.12%, and the yield is 93.8%.

[0105] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0106] One or more embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A method for extracting and refining a long carbon chain dibasic acid produced by a biological fermentation method, characterized in that: The following steps are included: 1) adding an acidic substance to the long-chain dibasic acid fermentation broth obtained by the biological fermentation method to adjust the pH value to 5.5-6.5, causing the broth to react and precipitate solids, and separating the solids to obtain a precipitate; 2) adding the precipitate into water, adding alkaline substances to adjust the pH value to ≥ 7.8, dissolving the precipitate, and obtaining a treated liquid; 3) adding an acidic substance to the treatment liquid to adjust the pH value to ≤4.5, causing the liquid to react and precipitate a solid, and separating the solid to obtain a crude long-chain dibasic acid; 4) Mixing the crude long-chain dibasic acid with an acid solution, and then melting and crystallizing the mixture to obtain a long-chain dibasic acid.

2. The extraction and purification method according to claim 1, characterized in that: In step 1) or / and step 3), the acidic substance includes chloroacetic acid.

3. The extraction and purification method according to claim 1, characterized in that: In step 1) or / and step 3), the acidic substance further comprises at least one of bisulfate, sulfuric acid, oxalic acid and citric acid.

4. The extraction and purification method according to any one of claims 1 to 3, characterized in that: Step 4) The acid solution is an oxalic acid aqueous solution, a chloroacetic acid aqueous solution or a citric acid aqueous solution, and the mass concentration of the acid is 1-5.5%.

5. The extraction and purification method according to any one of claims 1 to 3, characterized in that: In step 1), an acidic substance is added to adjust the pH value to 5.8-6.

2.

6. The extraction and purification method according to any one of claims 1 to 3, characterized in that: Step 1) firstly adjust the pH of the long carbon chain dibasic acid fermentation liquid to above 7.8 with alkali, and then add acidic substances to adjust the pH value to 5.5-6.

5.

7. The extraction and purification method according to any one of claims 1 to 3, characterized in that: Step 2) adding alkaline substances to adjust the pH value to 7.8-12; Step 3) adding acidic substances to adjust the pH value to 1.0-4.

5.

8. The extraction and purification method according to any one of claims 1 to 3, characterized in that: The long-chain dibasic acid is a straight-chain aliphatic dibasic acid containing 10 to 18 carbon atoms; the long-chain dibasic acid fermentation liquid is obtained from alkanes by a biological fermentation method, and sodium salt or potassium salt is added to the fermentation medium.

9. The extraction and purification method according to any one of claims 1 to 3, characterized in that: Step 1) comprises: heating the long carbon chain dibasic acid fermentation liquid to 45-65° C., adding an acidic substance to adjust the pH value; then cooling to 30-45° C., stirring for 1-1.5 hours, and performing solid-liquid separation to obtain a precipitate; Step 2) includes: adding alkaline substances at 45-65°C to adjust the pH value, and then using activated carbon for decolorization and filtering; Step 3) comprises: adding an acidic substance at 45-65° C. to adjust the pH value, stirring for 1-1.5 hours, and filtering.

10. The extraction and purification method according to any one of claims 1 to 3, characterized in that: Step 4) The melt crystallization is carried out by raising the temperature to 105-111°C, maintaining the temperature, and then cooling the temperature to crystallize.

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