Method for recovering L-serine in mother liquor
The impurities in the L-serine mother liquor are recovered through the ion exchange resin, which solves the problem of impurities enrichment of mother liquor in fermentation and enzyme methods, improves the product recovery rate and quality, and is suitable for large-scale production.
Patent Information
- Application Number
- CN202510365743.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-06-13
AI Technical Summary
Among the existing L-serine production methods, especially fermentation methods and enzyme methods, impurity enrichment in mother liquor leads to unstable product quality and untimely recycling will increase production costs.
The L-serine in the mother liquor is recovered by ion exchange resin, and the organic impurities and inorganic salts are removed through steps such as overcurrent, analysis, decolorization, pH adjustment, reduced pressure concentration, and cooling and crystallization, thereby improving product yield and quality.
It has achieved efficient removal of impurities in the mother liquor, improved the recovery rate and quality of the product, the total product yield is greater than 50%, and the finished L-serine content is above 99 wt%, which is suitable for large-scale production.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of L-serine recovery, and particularly to a technique for recovering L-serine from mother liquor. Background Art
[0002] L-serine, also known as L-silk serine and L-2-amino-3-hydroxypropionic acid, can be used as a nutritional supplement, a flavoring agent, and an amino acid drug. It is mainly used in amino acid infusions and, due to its special wettability, is also used in vanishing creams and cosmetics. As a non-essential amino acid, serine plays a role in the metabolism of fats and fatty acids and the growth of muscles. Since it contributes to the production of immunoglobulins and antibodies, serine is also required to maintain a healthy immune system. Serine plays a role in the manufacture and processing of cell membranes and the synthesis of muscle tissue and the sheath surrounding nerve cells.
[0003] Its production methods include protein hydrolysis method, fermentation method, chemical synthesis method, and enzymatic method. Among them, the enzymatic method uses serine hydroxymethyltransferase to catalyze the reversible synthesis of serine from formaldehyde and glycine. During the reaction process, pyridoxal phosphate (PLP) and tetrahydrofolic acid (THFA) are required as its cofactors. Since the main raw materials are widely available and inexpensive, and high-purity products can be synthesized, this method is currently the most promising method for serine production. There are many problems in the production of L-serine by the protein hydrolysis method. Specifically, first, there is a racemization effect during the hydrolysis process, the steps are cumbersome, and the loss rate of L-serine is high; second, the obtained amino acids are often mixed amino acids and need to be further separated and refined, resulting in relatively large pollution; third, the hydrolysis equipment is severely corroded; fourth, a large amount of eluent is required, causing serious pollution. The chemical method can use different chemical raw materials and different process routes, with a large production scale and easy separation and purification of products. However, the chemical synthesis method can only obtain DL-serine, and chemical resolution is required to obtain L-serine, which increases the cost and production complexity. Since the fermentation method and the enzymatic method overcome the disadvantages of the above two methods, they have become the main directions for the production and research of L-serine. However, there are problems in how to handle the mother liquor in both the fermentation method and the enzymatic method. There are various impurities in the fermentation broth and enzymatic conversion broth. The impurities in the mother liquor obtained after the extraction of the fermentation broth and enzymatic conversion broth show an enrichment phenomenon. Direct recycling and reuse will affect the product quality, and if the mother liquor is not recycled, it will increase the production cost. Therefore, an effective method for efficiently recovering the mother liquor is urgently needed. Summary of the Invention
[0004] To solve the above technical problems, the present invention provides a method for recovering L-serine from mother liquor. The method uses ion exchange resin to recover L-serine from the mother liquor, which is simple to operate and easy to control, has low cost, improves the product yield and quality, and can be used for large-scale production.
[0005] The technical solution adopted by the present invention is: A method for recovering L-serine from mother liquor, comprising the following steps: (1) Pass the L-serine mother liquor through a column of resin, controlling the flow rate and adsorption amount. After the flow-through is completed, rinse with deionized water until the ninhydrin sample at the resin outlet no longer turns purple. (2) Start collecting the low-content feed solution when ammonia water is passed through the column for desorption, and start collecting the high-content feed solution when the ninhydrin sample turns purple. Use a wide-range pH test paper with a pH range of 1-14 for sampling, and stop desorption when the sample at the outlet turns purple. (3) After passing the high-content feed solution in step (2) through a membrane system, perform decolorization, adjust the pH value, concentrate under reduced pressure, cool and crystallize, filter, and dry to obtain L-serine. The mother liquor after filtration can be continuously adsorbed and desorbed for recovery.
[0006] Preferably, in step (1), the resin is a cation exchange resin.
[0007] Preferably, in step (1), the flow rate is 0.5-1.0 BV of the resin volume, and the adsorption amount is 50-100 g of L-serine adsorbed per liter of resin.
[0008] Preferably, in step (2), the mass concentration of ammonia water is 2-7%.
[0009] Preferably, in step (3), the membrane system is one or two of a ceramic filter membrane, an ultrafiltration membrane, and a nanofiltration membrane.
[0010] Preferably, in step (3), the pH value is adjusted to 5.5-6.5.
[0011] The beneficial effects of adopting the above technical solution are as follows: The present invention uses ion exchange resin to recover L-serine from mother liquor, which can not only remove organic impurities in the mother liquor but also remove inorganic salts. The operation is simple and easy to control, the cost is low, the product yield and quality are improved, and it can be used for large-scale production.
[0012] The total product yield in the mother liquor of the present invention is greater than 50%, and the content of the finished L-serine is more than 99 wt%. Detailed implementation mode
[0013] The present invention will be further described in detail below in conjunction with specific implementation modes. Example 1
[0014] (1) Take 400 mL of mother liquor containing 60 g of L-serine, pass it through a column of resin, control the flow rate to be 0.7 BV of the resin volume. After the flow-through is completed, rinse with deionized water until the ninhydrin sample at the resin outlet no longer turns purple.
[0015] (2) Start collecting the low-content feed liquid by column elution with 4% ammonia water. Start collecting the high-content feed liquid when the ninhydrin spotting turns purple. Spot with a pH 1-14 wide-range test paper and stop elution when the spotting at the outlet turns purple. (3) After subjecting the high-content feed liquid from the previous step to ceramic filtration and ultrafiltration membrane system, 1350 mL of feed liquid is obtained. Add 6.5 g of activated carbon and stir at room temperature for 40 min for decolorization. Filter to remove carbon. The filtrate passes through a microporous filter membrane (the pore size of the microporous filter membrane is 0.45 μm). Adjust the pH value of the feed liquid to 6.2 and concentrate it under reduced pressure at 90 °C with a vacuum degree ≤ -0.095 MPa until it reaches 135 g. Then cool for crystallization. After crystals appear, conduct crystal cultivation for 45 min. After the crystal cultivation is completed, continue to cool to 20 °C and stir at a constant temperature for 30 min. Filter to obtain wet powder, and dry it at 100 °C to obtain 31.67 g of dry powder with a content of 99.44 wt% and a total yield of 52.78%. Example 2
[0016] (1) Take 350 mL of mother liquor containing 55 g of L-serine, pass it through the resin column with a controlled flow rate of 0.5 BV of the resin volume. After the flow-through is completed, top the material with deionized water until the ninhydrin spotting at the resin outlet does not turn purple.
[0017] (2) Start collecting the low-content feed liquid by column elution with 2% ammonia water. Start collecting the high-content feed liquid when the ninhydrin spotting turns purple. Spot with a pH 1-14 wide-range test paper and stop elution when the spotting at the outlet turns purple. (3) After subjecting the high-content feed liquid from the previous step to ceramic filtration and nanofiltration membrane system, 1080 mL of feed liquid is obtained. Add 5 g of activated carbon and stir at room temperature for 40 min for decolorization. Filter to remove carbon. The filtrate passes through a microporous filter membrane (the pore size of the microporous filter membrane is 0.45 μm). Adjust the pH value of the feed liquid to 6.5 and concentrate it under reduced pressure at 90 °C with a vacuum degree ≤ -0.095 MPa until it reaches 120 g. Then cool for crystallization. After crystals appear, conduct crystal cultivation for 45 min. After the crystal cultivation is completed, continue to cool to 20 °C and stir at a constant temperature for 30 min. Filter to obtain wet powder, and dry it at 100 °C to obtain 31.45 g of dry powder with a content of 99.69 wt% and a total yield of 57.18%. Example 3
[0018] Take 500 mL of mother liquor containing 75 g of L-serine, pass it through the resin column with a controlled flow rate of 1.0 BV of the resin volume. After the flow-through is completed, top the material with deionized water until the ninhydrin spotting at the resin outlet does not turn purple.
[0019] (2) Start collecting the low-content feed liquid by column elution with 7% ammonia water. Start collecting the high-content feed liquid when the ninhydrin spotting turns purple. Spot with a pH 1-14 wide-range test paper and stop elution when the spotting at the outlet turns purple. (3)The 1700 mL of the high-content feed solution obtained in the previous step was passed through a ceramic membrane filtration system, 8 g of activated carbon was added, and the mixture was stirred at room temperature for 40 min for decolorization, followed by filtration to remove carbon. The filtrate was passed through a microporous membrane (the pore size of the microporous membrane was 0.45 μm). The pH value of the feed solution was adjusted to 5.5, and it was concentrated under reduced pressure at 90 °C with a vacuum degree of ≤ -0.095 MPa until it reached 165 g. Then, the temperature was lowered for crystallization. After crystals appeared, crystal cultivation was carried out for 45 min. After the crystal cultivation was completed, the temperature was further lowered to 20 °C, and the mixture was kept warm and stirred for 30 min, followed by filtration to obtain wet powder. The wet powder was dried at 100 °C to obtain 41.54 g of dry powder with a content of 99.52 wt% and a total yield of 55.38%.
[0020] As can be seen from Examples 1-3, the method of the present invention can greatly improve the recovery rate and quality of the product. The total yield of the product is greater than 50%, and the content of the finished product L-serine is above 99 wt%.
[0021] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
Claims
1. A method for recovering L-serine in a mother liquor, characterized in that The following steps are involved: (1) Take L-serine mother liquor and load it onto the column flow resin, control the flow rate and adsorption amount, and after the flow is completed, top up with deionized water until the ninhydrin spot at the resin outlet does not turn purple; (2) When ammonia is applied to the column for analysis, low-content liquid begins to be collected. When the ninhydrin spot turns purple, high-content liquid begins to be collected. Use a pH 1-14 wide-band test paper to spot the sample. Stop the analysis when the outlet spot turns purple. (3) The high-content feed liquid of step (2) is passed through a membrane system, decolorized, pH adjusted, concentrated under reduced pressure, cooled for crystallization, filtered, and dried to obtain L-serine. The mother liquor after filtration can be further recovered by adsorption and analysis.
2. A method for recovering L-serine in a mother liquor according to claim 1, characterized in that: In the step (1), the resin is a cation exchange resin.
3. A method for recovering L-serine in a mother liquor according to claim 1, characterized in that: In the step (1), the flow rate is 0.5-1.0 BV of the resin volume, and the adsorption amount is 50-100 g of L-serine per liter of resin.
4. A method for recovering L-serine in a mother liquor according to claim 1, characterized in that: In the step (2), the mass concentration of ammonia water is 2-7%.
5. A method for recovering L-serine in a mother liquor according to claim 1, characterized in that: In the step (3), the membrane system is one or two of a ceramic filtration membrane, an ultrafiltration membrane, and a nanofiltration membrane.
6. A method for recovering L-serine in a mother liquor according to claim 1, characterized in that: In the step (3), the pH value is adjusted to 5.5-6.5.