A method for preparing sodium glutamate directly from glutamic acid fermentation broth by cation displacement dialysis

Abstract

The present application relates to monosodium glutamate clean production technology field, specifically to a kind of method for preparing sodium glutamate directly from glutamic acid fermentation liquor using cation replacement dialysis, the method comprises: glutamic acid fermentation liquor is passed into cation replacement dialysis device and sodium ion aqueous solution carry out ammonium ion and sodium ion cation replacement dialysis, finally obtain sodium glutamate and ammonia water or ammonium salt, wherein, the main component of glutamic acid fermentation liquor is ammonium glutamate.The method can realize the direct conversion from ammonium glutamate to sodium glutamate, and the method has the advantages of few process steps, simple flow, environment-friendly and low energy consumption.

Description

Technical Field

[0001] This invention relates to the field of clean monosodium glutamate (MSG) production technology, specifically to a method for preparing monosodium glutamate directly from glutamic acid fermentation broth using cation exchange dialysis. Background Technology

[0002] Monosodium glutamate (MSG) is an important seasoning that enriches and enhances the umami flavor of food and is widely used in the food processing industry. my country is a major producer of MSG, with an annual output of 2.95 million tons (based on monosodium glutamate), accounting for 76% of global production, and annual exports exceeding 750,000 tons.

[0003] The industrial production of monosodium glutamate (MSG) mainly extracts glutamic acid from glutamic acid fermentation broth (whose main component is ammonium glutamate) using an "isoelectric crystallization-acid-base neutralization" process. During isoelectric crystallization, a large amount of sulfuric acid is added to adjust the pH of the fermentation broth to the isoelectric point of glutamic acid (3.22) to extract glutamic acid crystals. The obtained glutamic acid crystals are then further neutralized with sodium carbonate to obtain monosodium glutamate (MSG). Figure 1 As shown in the figure, the supernatant after separating glutamic acid crystals in this method is called "isoelectric mother liquor," which contains high COD (10,000–40,000 mg / L), high concentrations of ammonium ions (15,000–25,000 mg / L), and high concentrations of sulfate ions (15,000–50,000 mg / L), and has a low pH (2.0–3.4), making it difficult to process. Microbial growth using the isoelectric mother liquor is inhibited by the high ammonium and sulfate content. In the industry, concentrating this mother liquor and then spray-granulating it to prepare compound fertilizer is not only energy-intensive but also causes secondary pollution.

[0004] Patents CN200910243319.6, CN200910243320.9, and CN201010034136.6 disclose a method for regenerating acids and bases from an isoelectric mother liquor of glutamic acid (e.g., Figure 2 As shown, the high concentration of ammonium sulfate in the isoelectric mother liquor is regenerated into sulfuric acid and ammonia by bipolar membrane electrodialysis. This method uses an electric field as the driving force, which will cause serious membrane fouling to such high COD feed liquor as the isoelectric mother liquor, making the corresponding industrial process difficult to carry out.

[0005] The journal *Journal of Membrane Science*, 2022, 658, reports a method for treating glutamate fermentation broth using the Downan dialysis technique (which does not require an electric field). Figure 3As shown, an ammonium glutamate aqueous solution and sulfuric acid are placed on opposite sides of a cation exchange membrane, allowing ammonium ions to exchange with hydrogen ions across the membrane (Daonan dialysis). On one side of the membrane, acidified glutamate is obtained, while on the other side, an ammonium sulfate aqueous solution with almost no COD is obtained. This avoids obtaining waste liquid with high salt and high COD, and also avoids membrane fouling associated with the aforementioned electrodialysis process. However, because glutamate has low solubility at its isoelectric point (glutamate solubility is 8.6 g / L at 25°C), using this method to treat actual glutamate fermentation broth (glutamate concentration greater than 100 g / L) results in the formation of a large amount of glutamate crystals within the membrane stack, clogging the flow channels and making practical operation difficult. As stated, the ammonium glutamate concentration used in the article is 10 g / L (calculated as glutamate), which is far lower than the actual glutamate concentration in the glutamate fermentation broth (100-300 g / L). Currently, most cation exchange dialysis devices in this field are plate and frame type cation exchange dialysis membrane stacks with narrow flow channels (0.5 mm-3 mm). When processing actual glutamate fermentation broth, they will face the problem of glutamate crystals clogging the membrane stack flow channels, making it difficult to continuously carry out ammonium hydrogen exchange. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a method for directly preparing monosodium glutamate from glutamate fermentation broth (the main component of ammonium glutamate) using cation exchange dialysis. This method can achieve the direct conversion from ammonium glutamate to monosodium glutamate, and has the advantages of fewer process steps, simpler process, environmental friendliness, and low energy consumption.

[0007] To achieve this objective, the present invention provides a method for directly preparing monosodium glutamate (MSG) from glutamate fermentation broth using cation exchange dialysis. The method includes passing the glutamate fermentation broth through a cation exchange dialysis device to perform ammonium-sodium ion cation exchange dialysis with an aqueous sodium ion solution, ultimately obtaining MSG and ammonia or ammonium salt, wherein the main component of the glutamate fermentation broth is ammonium glutamate.

[0008] The cation exchange dialysis device includes one or more cation exchange dialysis modules connected in series and / or in parallel, as well as associated pumps, pipes, and valves. The cation exchange dialysis module includes a cation exchange dialysis membrane and salt and alkali chambers separated by the cation exchange dialysis membrane, such as... Figure 4 As shown, the glutamic acid fermentation broth is passed into the salt chamber, and the sodium ion aqueous solution is passed into the alkali chamber. The ammonium ions in the glutamic acid fermentation broth passing into the salt chamber and the sodium ions in the sodium ion aqueous solution passing into the alkali chamber undergo ion exchange through a cation exchange dialysis membrane. That is, ammonium ions migrate across the cation exchange dialysis membrane into the alkali chamber, and sodium ions migrate across the cation exchange dialysis membrane into the salt chamber. Thus, monosodium glutamate is obtained in the salt chamber, and ammonia water or ammonium salt is obtained in the alkali chamber.

[0009] The cation exchange dialysis module can be a plate-and-frame cation exchange dialysis membrane stack, a tubular cation exchange dialysis membrane module, or a spiral wound cation exchange dialysis membrane module.

[0010] The plate-and-frame cation exchange dialysis membrane stack includes multiple flat-plate cation exchange dialysis membranes and separators, as well as salt and alkali chambers alternately separated by the multiple flat-plate cation exchange dialysis membranes. The tubular cation exchange dialysis membrane assembly includes multiple tubular cation exchange dialysis membranes and salt chambers (outside the membrane tubes, shell side) and alkali chambers (inside the membrane tubes, tube side) separated by the tubular cation exchange dialysis membranes. The spiral-wound cation exchange dialysis membrane assembly includes one or more flat-plate cation exchange dialysis membranes rolled into a membrane roll and separators, as well as salt and alkali chambers separated by the cation exchange dialysis membranes.

[0011] The cation exchange dialysis membrane can be any cation exchange membrane well known to those skilled in the art, which can be purchased from the market, such as conventional electrodialysis cation exchange membranes, monovalent selective cation exchange membranes (which allow monovalent cations to pass through preferentially while blocking divalent and higher valence cations from passing through), alkali-resistant cation exchange membranes, or obtained through modification of ion exchange membranes (doping modification and surface modification).

[0012] Preferably, the concentration of the initial glutamic acid fermentation broth (calculated as glutamic acid) is 50-350 g / L.

[0013] The initial total amount of sodium ions in the sodium ion aqueous solution is greater than the initial total amount of glutamate ions in the glutamate fermentation broth.

[0014] In this invention, the linear velocity of the feed solution in the cation exchange dialysis unit is 0.5-7 cm / s.

[0015] The temperature of the salt chamber and alkali chamber feed solutions in the cation exchange dialysis is 20-60℃, that is, the temperature of the cation exchange dialysis is 20-60℃.

[0016] The sodium ion aqueous solution refers to a neutral to alkaline aqueous solution containing sodium ions, including but not limited to aqueous solutions of sodium hydroxide, sodium sulfate, sodium chloride, sodium carbonate, or sodium bicarbonate.

[0017] Furthermore, the sodium ion aqueous solution is preferably an alkaline sodium ion-containing aqueous solution, including but not limited to sodium hydroxide, sodium carbonate, or sodium bicarbonate. When the sodium ion aqueous solution is an alkaline sodium ion-containing aqueous solution, some of the ammonium ions migrating into the alkaline chamber combine with hydroxide ions to generate ammonia, promoting the migration of ammonium ions into the alkaline chamber, thereby promoting the conversion of ammonium glutamate in the salt chamber to monosodium glutamate.

[0018] Specifically, when the sodium ion aqueous solution is sodium carbonate or sodium bicarbonate, the temperature of the salt chamber feed solution and the alkali chamber feed solution in the cation exchange dialysis is 40-60°C.

[0019] Preferably, when the sodium ion aqueous solution is an alkaline sodium ion-containing aqueous solution, the method for preparing sodium glutamate directly from glutamate fermentation broth using cation exchange dialysis according to the present invention further includes blowing air into the alkaline chamber of the cation exchange dialysis assembly during cation exchange dialysis, such as... Figure 6 As shown, blowing air into the alkali chamber of the cation exchange dialysis unit can strip ammonia molecules from the alkali chamber, promoting the dissociation equilibrium of ammonium / ammonia towards the generation of ammonia molecules. This increases the driving force for ammonium ions in the salt chamber to migrate across the cation exchange dialysis membrane into the alkali chamber. At the same time, after the ammonia is stripped from the alkali chamber, the leakage of ammonia molecules through the cation exchange dialysis membrane into the salt chamber is reduced.

[0020] In this invention, the aforementioned method for directly preparing monosodium glutamate (MSG) from glutamate fermentation broth using cation exchange dialysis can be described as a single-stage batch processing method. However, due to the migration equilibrium of ammonium and sodium ions during cation exchange dialysis, a large amount of initial total sodium ion content is often required to achieve a high MSG conversion rate in the salt chamber (the MSG conversion rate is the ratio of the MSG concentration in the MSG solution obtained from the salt chamber to the initial glutamate concentration in the glutamate fermentation broth). As a preferred embodiment of this invention, the method for directly preparing MSG from glutamate fermentation broth using cation exchange dialysis further includes replacing the sodium ion aqueous solution with fresh sodium ion solution during the cation exchange dialysis process.

[0021] In the aforementioned method of replacing the sodium ion aqueous solution with fresh water, the sodium ion aqueous solution is replaced once or multiple times.

[0022] Preferably, in the method of replacing the sodium ion aqueous solution with fresh sodium ion aqueous solution, the sum of the initial total amount of sodium ions in all sodium ion aqueous solutions is greater than the initial total amount of glutamate ions in the glutamate fermentation broth.

[0023] To further reduce the required initial total sodium ion content, the method for directly preparing monosodium glutamate from glutamate fermentation broth using cation exchange dialysis according to this invention also includes a multi-stage countercurrent treatment method. The multi-stage countercurrent treatment method involves configuring the cation exchange dialysis device into multiple cation exchange dialysis modules. Each cation exchange dialysis module is a stage, including a cation exchange dialysis membrane and salt and alkali chambers separated by the cation exchange dialysis membrane. The salt chambers of multiple stages of cation exchange dialysis modules are connected in series, and the alkali chambers of multiple stages of cation exchange dialysis modules are connected in series. The initial glutamate fermentation broth is passed into the salt chamber of the first-stage cation exchange dialysis module, and the initial sodium ion aqueous solution is passed into the alkali chamber of the last-stage cation exchange dialysis module. The glutamic acid fermentation broth is passed sequentially through the salt chambers of the cation exchange dialysis units at each stage, from the first stage to the last stage, and undergoes cation exchange dialysis with the sodium ion aqueous solution of partially recovered ammonium from each stage's cation exchange dialysis unit. Sodium glutamate is obtained in the salt chamber of the last stage's cation exchange dialysis unit. The sodium ion aqueous solution is passed sequentially through the alkali chambers of the cation exchange dialysis units at each stage, from the last stage to the first stage, and ammonia water or ammonium salt is obtained in the alkali chamber of the first stage's cation exchange dialysis unit.

[0024] Taking the three-stage reverse flow processing method in the multi-stage reverse flow processing method as an example, such as Figure 7 As shown, the initial glutamate fermentation broth is passed into the salt chamber 1 of the first-stage cation exchange dialysis unit, and the initial sodium ion aqueous solution is passed into the alkaline chamber 3 of the final-stage cation exchange dialysis unit. The glutamate fermentation broth passes sequentially through the salt chamber 1 of the first-stage cation exchange dialysis unit, the salt chamber 2 of the second-stage cation exchange dialysis unit, and the salt chamber 3 of the third-stage cation exchange dialysis unit; the sodium ion aqueous solution passes sequentially through the alkaline chamber 3 of the third-stage cation exchange dialysis unit, the alkaline chamber 2 of the second-stage cation exchange dialysis unit, and the alkaline chamber 1 of the first-stage cation exchange dialysis unit. Sodium glutamate is obtained in the salt chamber 3 of the third-stage cation exchange dialysis unit, and ammonia or ammonium salt is obtained in the alkaline chamber 1 of the first-stage cation exchange dialysis unit.

[0025] Preferably, the multi-stage countercurrent treatment method for directly preparing sodium glutamate from glutamate fermentation broth using cation exchange dialysis has three or more stages.

[0026] The technical solution of this invention, which involves replacing the sodium ion aqueous solution with fresh sodium ion water and using a multi-stage countercurrent treatment method, increases the concentration difference between sodium and ammonium ions across the cation exchange dialysis membrane, thereby increasing the driving force for ion migration across the cation exchange dialysis membrane and increasing the ion migration flux. At the same time, it breaks the limitation of equilibrium concentration in single-stage batch treatment, significantly reducing the total amount of sodium ions in the sodium ion aqueous solution that needs to be introduced into the alkali chamber, especially when using non-alkaline sodium ion aqueous solutions.

[0027] Compared with existing technologies, the method for directly preparing monosodium glutamate from glutamic acid fermentation broth provided by this invention (e.g.) Figure 5 (As shown) This invention can obtain monosodium glutamate (MSG) without the need for isoelectric crystallization, centrifugation, and acid-base neutralization, shortening the process flow and saving acid and alkali consumption compared to existing production processes. It avoids the generation of high-salt, high-COD wastewater in existing processes, obtaining relatively pure ammonia or ammonium salts in the alkali chamber, which can be reused in glutamic acid fermentation or used as a byproduct. Compared to electrodialysis, the cation exchange dialysis method of this invention has the advantage of low energy consumption and is less prone to membrane fouling when applied to glutamic acid fermentation broth with many impurities. Furthermore, this invention uses sodium-ammonium exchange to directly prepare MSG, avoiding the problems of large amounts of glutamic acid crystallization precipitating and clogging the flow channel in the ammonium hydrogen exchange process described in the Journal of Membrane Science, 2022, 658, which can only handle low-concentration (glutamic acid concentration less than 30 g / L) solutions. It can handle solutions of 50–350 g / L (based on glutamic acid), thus significantly improving the treatment efficiency of glutamic acid fermentation broth. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the existing monosodium glutamate (MSG) production process, which uses isoelectric crystallization-acid-base neutralization to prepare monosodium glutamate from glutamic acid fermentation broth.

[0029] Figure 2 This is a process flow diagram of regenerating acids and bases from isoelectric mother liquor of glutamic acid using bipolar membrane electrodialysis technology;

[0030] Figure 3 This is a flowchart of the preparation of glutamic acid from glutamic acid fermentation broth using the Daonan dialysis technology;

[0031] Figure 4 This is a schematic diagram of ion migration during the cation exchange dialysis process in the cation exchange dialysis device described in this invention;

[0032] Figure 5 This is a process flow diagram of the present invention for preparing sodium glutamate from glutamic acid fermentation broth using cation exchange dialysis.

[0033] Figure 6 This is a schematic diagram of blowing air into the alkali chamber of the cation exchange dialysis component during cation exchange dialysis treatment as described in this invention;

[0034] In the diagram: solid lines represent the direction of the liquid in the salt chamber, and dashed lines represent the direction of the liquid in the alkali chamber.

[0035] Figure 7 This is a process diagram of the multi-stage countercurrent processing method (taking the three-stage countercurrent processing method as an example) described in this invention;

[0036] Figure 8This is a schematic diagram of the plate-and-frame cation exchange dialysis membrane stack structure described in this invention;

[0037] Figure 9 This is a process diagram of the six-stage countercurrent processing method described in this invention;

[0038] Figure 10 This is a process diagram of the four-stage countercurrent processing method described in this invention;

[0039] In the diagram: Salt chamber 1 and alkali chamber 1 represent the salt chamber and alkali chamber of the first-stage cation exchange dialysis unit in the above treatment method, respectively; Salt chamber 2 and alkali chamber 2 represent the salt chamber and alkali chamber of the second-stage cation exchange dialysis unit in the above treatment method, respectively; Salt chamber 3 and alkali chamber 3 represent the salt chamber and alkali chamber of the third-stage cation exchange dialysis unit in the above treatment method, respectively; Salt chamber 4 and alkali chamber 4 represent the salt chamber and alkali chamber of the fourth-stage cation exchange dialysis unit in the above treatment method, respectively; Salt chamber 5 and alkali chamber 5 represent the salt chamber and alkali chamber of the fifth-stage cation exchange dialysis unit in the above treatment method, respectively; Salt chamber 6 and alkali chamber 6 represent the salt chamber and alkali chamber of the sixth-stage cation exchange dialysis unit in the above treatment method, respectively. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments.

[0041] Example 1

[0042] The cation exchange dialysis unit uses a plate-and-frame cation exchange dialysis membrane stack (e.g.) Figure 8 As shown, the salt and alkali chambers are formed by alternating separation of five cation exchange membranes with an effective area of ​​12.8cm × 6.9cm and six partitions of the same size mesh.

[0043] 200 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 100 g / L was passed into the salt chamber of a plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration was 12.2 g / L. 200 mL of sodium sulfate solution, with a total sodium ion content 1.1 times the total glutamic acid ion content, was passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane stack was 3 cm / s, and the temperature of the feed solution in each chamber was 20-25℃.

[0044] After 2.8 hours of cation exchange dialysis, cations reached migration equilibrium across the cation exchange membrane, at which point the cation exchange dialysis was stopped. The sodium glutamate conversion rate was 52.4%, and the sodium ion membrane flux was 0.57 mol / m³. 2 / h.

[0045] Example 2

[0046] The cation exchange dialysis apparatus is the same as in Example 1.

[0047] 200 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 100 g / L was passed into the salt chamber of a plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration was 12.2 g / L. 200 mL of sodium sulfate solution, with a total sodium ion content three times the total glutamic acid ion content, was passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane stack was 3 cm / s, and the temperature of the feed solution in each chamber was 20-25℃.

[0048] After 3.8 hours of cation exchange dialysis, cations reached migration equilibrium across the cation exchange membrane, at which point the cation exchange dialysis was stopped. The sodium glutamate conversion rate was 75%, and the sodium ion membrane flux was 0.60 mol / m³. 2 / h. Compared to Example 1, the conversion rate of monosodium glutamate increased by 22.6%, which is due to the increased initial total amount of sodium ions in the alkalinity chamber of the plate-and-frame cation exchange dialysis membrane, promoting the ion exchange of ammonium and sodium ions through the cation exchange dialysis membrane.

[0049] Example 3

[0050] The cation exchange dialysis unit uses one spiral wound cation exchange dialysis membrane module, employing an LCM cation exchange membrane manufactured by Liaoning Yichen Membrane Technology Co., Ltd., with an effective membrane area of ​​0.2 m². 2 .

[0051] 1 L of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 50 g / L was passed into the salt chamber of a spiral-wound cation exchange dialysis membrane module, with an ammonium ion concentration of 6.2 g / L. 1 L of sodium chloride solution, with a total sodium ion content 1.5 times the total glutamic acid ion content, was passed into the alkali chamber of the spiral-wound cation exchange dialysis membrane module as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the module was 0.5 cm / s, and the feed solution temperature in each chamber was 20-25℃.

[0052] After 2.2 hours of cation exchange dialysis, cations reached migration equilibrium across the cation exchange membrane, at which point the cation exchange dialysis was stopped. The sodium glutamate conversion rate was 60%, and the sodium ion membrane flux was 0.48 mol / m³. 2 / h.

[0053] Example 4

[0054] The cation exchange dialysis apparatus is the same as in Example 1. 200 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 300 g / L is passed into the salt chamber of the plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration is 36.7 g / L. 200 mL of sodium hydroxide solution, with a total sodium ion content 1.5 times the total glutamic acid ion content, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane stack is 7 cm / s, and the temperature of the feed solution in each chamber is 20-25°C.

[0055] After 5.4 hours of cation exchange dialysis, the sodium glutamate conversion rate reached 99.5%, and the sodium ion membrane flux was 1.7 mol / m³. 2 / h. When the sodium ion aqueous solution is sodium hydroxide, the ammonium ions migrating into the alkaline chamber combine with hydroxide ions to form ammonia, which promotes the migration of ammonium ions into the alkaline chamber and greatly increases the conversion rate of monosodium glutamate.

[0056] Example 5

[0057] The cation exchange dialysis apparatus is the same as in Example 1. 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 50 g / L is passed into the salt chamber of the plate-and-frame cation exchange dialysis membrane stack, with an ammonium ion concentration of 6.2 g / L. 300 mL of sodium bicarbonate solution, with a total sodium ion content 1.5 times the total glutamic acid ion content, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane stack is 7 cm / s, and the temperature of the feed solution in each chamber is 58-60°C.

[0058] After 2 hours of cation exchange dialysis, the sodium glutamate conversion rate reached 82.2%, and the sodium ion membrane flux was 0.95 mol / m³. 2 / h. Compared with a feed temperature of 25℃ in each chamber, the conversion rate of monosodium glutamate increased by 23%, and the sodium ion membrane flux increased by 47.4%.

[0059] Example 6

[0060] The cation exchange dialysis apparatus is the same as in Example 1. 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 50 g / L is passed into the salt chamber of the plate-and-frame cation exchange dialysis membrane stack, with an ammonium ion concentration of 6.1 g / L. 300 mL of sodium carbonate solution, with a total sodium ion content three times the total glutamic acid ion content, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane stack is 3 cm / s, and the temperature of the feed solution in each chamber is 60°C.

[0061] After 2.3 hours of cation exchange dialysis, the sodium glutamate conversion rate reached 85%, and the sodium ion membrane flux was 0.86 mol / m³. 2 / h. Compared with a feed temperature of 25℃ in each chamber, the conversion rate of monosodium glutamate increased by 10%, and the sodium ion membrane flux increased by 41.9%.

[0062] Example 7

[0063] The cation exchange dialysis unit uses a plate-and-frame cation exchange dialysis membrane stack (e.g.) Figure 8 As shown, the salt and alkali chambers are formed by alternating separation of nine cation exchange membranes with an effective area of ​​12.8cm × 6.9cm and ten partitions of the same size mesh.

[0064] 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 250 g / L was passed into the salt chamber of a plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration was 30.6 g / L. 300 mL of sodium bicarbonate solution, with a total sodium ion content twice that of glutamic acid, was passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. Aeration was then introduced into the alkali chamber of the cation exchange dialysis membrane stack. Figure 6 As shown. The linear velocity of the feed liquid in each chamber within the membrane stack is 2 cm / s, and the temperature of the feed liquid in each chamber is 40℃.

[0065] After 7 hours of cation exchange dialysis, the sodium glutamate conversion rate reached 92.2%, and the sodium ion membrane flux was 0.85 mol / m³. 2 / h. Compared with not blowing air into the alkalinity chamber of a plate-and-frame cation exchange dialysis membrane, the conversion rate of monosodium glutamate increased by 12.2%.

[0066] Example 8

[0067] The cation exchange dialysis apparatus is the same as in Example 7. 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 80 g / L is passed into the salt chamber of the plate-and-frame cation exchange dialysis membrane stack, resulting in an ammonium ion concentration of 9.8 g / L. 300 mL of sodium carbonate solution, with a total sodium ion content 2.5 times the total glutamic acid ion content, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. Aeration is introduced into the alkali chamber of the cation exchange dialysis membrane stack, such as... Figure 6 As shown. The linear velocity of the feed liquid in each chamber within the membrane stack is 4 cm / s, and the temperature of the feed liquid in each chamber is 55℃.

[0068] After 2.1 hours of cation exchange dialysis, the sodium glutamate conversion rate reached 92.8%, and the sodium ion membrane flux was 0.9 mol / m³. 2 / h. Compared with not blowing air into the alkalinity chamber of a plate-and-frame cation exchange dialysis membrane, the conversion rate of monosodium glutamate increased by 21.4%.

[0069] Example 9

[0070] The cation exchange dialysis apparatus is the same as in Example 7. 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 100 g / L is passed into the salt chamber of the plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration is 12.2 g / L. 300 mL of sodium chloride solution, with a total sodium ion content three times the initial total glutamic acid ion content in the fermentation broth, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane stack is 2.5 cm / s, and the temperature of the feed solution in each chamber is 25-30°C. After 3 hours of cation exchange dialysis, a fresh sodium ion aqueous solution is replaced. 300 mL of sodium chloride solution, with a total sodium ion content three times the initial total glutamic acid ion content in the fermentation broth, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for continued cation exchange dialysis.

[0071] The cation exchange dialysis was carried out for a total of 4.8 hours, with a sodium glutamate conversion rate of 92% and a sodium ion membrane flux of 0.50 mol / m³. 2 / h. Compared to a sodium chloride solution where the total amount of sodium ions added at once is 6 times the initial total amount of glutamate ions, this method reduces the initial total amount of sodium ions required to achieve the same monosodium glutamate conversion rate by 52%.

[0072] Example 10

[0073] The cation exchange dialysis apparatus is the same as in Example 7. 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 225 g / L is passed into the salt chamber of the plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration is 27.6 g / L. 200 mL of sodium sulfate solution, with a total sodium ion content twice the initial total glutamic acid ion content in the glutamic acid fermentation broth, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane stack is 5 cm / s, and the temperature of the feed solution in each chamber is 25-30°C. After 4.5 hours of cation exchange dialysis, a fresh sodium ion aqueous solution is replaced for the first time. 200 mL of sodium sulfate solution, with a total sodium ion content twice the initial total glutamic acid ion content in the glutamic acid fermentation broth, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. After 2.3 hours of cation exchange dialysis, a fresh sodium ion aqueous solution was used as the replacement medium. 200 mL of sodium sulfate solution, with a total sodium ion content 1.5 times that of the initial total glutamate ion content in the glutamate fermentation broth, was passed into the alkalinity chamber of the plate-and-frame cation exchange dialysis membrane as the replacement medium, and cation exchange dialysis continued.

[0074] The cation exchange dialysis was carried out for a total of 7.5 hours. The sodium glutamate conversion rate in the salt chamber of the plate-and-frame cation exchange dialysis membrane reached 95.1%, and the sodium ion membrane flux was 0.73 mol / m³. 2 / h. Compared to a sodium sulfate solution where the total amount of sodium ions added at once is 5.5 times the initial total amount of glutamate ions, this method reduces the initial total amount of sodium ions required to achieve the same monosodium glutamate conversion rate by 71%.

[0075] Example 11

[0076] The cation exchange dialysis apparatus is the same as in Example 7. 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 200 g / L is passed into the salt chamber of the plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration is 24.5 g / L. 300 mL of sodium bicarbonate solution, with a total sodium ion content 1.5 times the initial total glutamic acid ion content in the fermentation broth, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane stack is 5 cm / s, and the temperature of the feed solution in each chamber is 58-60°C. After 3.1 hours of cation exchange dialysis, a fresh sodium ion aqueous solution is replaced. 300 mL of sodium bicarbonate solution, with a total sodium ion content 1.5 times the initial total glutamic acid ion content in the fermentation broth, is passed into the alkali chamber of the plate-and-frame cation exchange dialysis membrane stack as the replacement medium, and cation exchange dialysis continues.

[0077] The cation exchange dialysis was carried out for a total of 4.4 hours, with a sodium glutamate conversion rate of 95.5% and a sodium ion membrane flux of 1.11 mol / m³. 2 / h. Compared to Example 5, the monosodium glutamate conversion rate increased by 13.3%.

[0078] Example 12

[0079] Monosodium glutamate is prepared using a three-stage countercurrent process, such as... Figure 7 As shown, the cation exchange dialysis device is configured as three identical plate-and-frame cation exchange dialysis membrane stacks, each stack being a single stage, and each stack being the same as in Example 1. The salt chambers of the three membrane stacks are connected in series, and the alkali chambers of the three membrane stacks are connected in series.

[0080] 0.9 L of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 200 g / L was passed into the salt chamber of the first-stage plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration was 24.5 g / L. 0.9 L of sodium sulfate solution, with a total sodium ion content 1.1 times the initial total glutamic acid ion content in the fermentation broth, was passed into the alkali chamber of the third-stage plate-and-frame cation exchange dialysis membrane stack as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack was 4 cm / s, and the temperature of the feed solution in each chamber was 25 °C. The glutamic acid fermentation broth was passed sequentially through the salt chambers of the first to third-stage plate-and-frame cation exchange dialysis membrane stacks, and the sodium sulfate solution was passed sequentially through the alkali chambers of the third to first-stage plate-and-frame cation exchange dialysis membrane stacks, undergoing cation exchange dialysis. Sodium glutamate was obtained in the salt chamber of the third-stage plate-and-frame cation exchange dialysis membrane stack, and ammonium salt was obtained in the alkali chamber of the first-stage plate-and-frame cation exchange dialysis membrane stack.

[0081] The cation exchange dialysis was performed for 4.4 hours, achieving a sodium glutamate conversion rate of 95% and a sodium ion membrane flux of 1.0 mol / m³. 2 / h. Compared to single-stage batch processing, the three-stage countercurrent processing method, under the same sodium sulfate solution and operating conditions, increases the conversion rate of monosodium glutamate by 20%.

[0082] Example 13

[0083] Monosodium glutamate was prepared using a six-stage countercurrent process, such as... Figure 9 As shown, the cation exchange dialysis device is configured as six identical plate-and-frame cation exchange dialysis membrane stacks, each stack being a single stage, and each stack being the same as in Example 1. The salt chambers of the six membrane stacks are connected in series, and the alkali chambers of the six membrane stacks are connected in series.

[0084] 1.5 L of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 300 g / L was passed into the salt chamber of the first-stage plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration was 37 g / L. 1.5 L of sodium sulfate solution, with a total sodium ion content 1.5 times the initial total glutamic acid ion content in the fermentation broth, was passed into the alkali chamber of the sixth-stage plate-and-frame cation exchange dialysis membrane stack as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack was 5 cm / s, and the temperature of the feed solution in each chamber was 25 °C. The glutamic acid fermentation broth was passed sequentially through the salt chambers of the first to sixth-stage plate-and-frame cation exchange dialysis membrane stacks, and the sodium sulfate solution was passed sequentially through the alkali chambers of the sixth to first-stage plate-and-frame cation exchange dialysis membrane stacks for cation exchange dialysis. Sodium glutamate was obtained in the salt chamber of the sixth-stage plate-and-frame cation exchange dialysis membrane stack, and ammonium salt was obtained in the alkali chamber of the first-stage plate-and-frame cation exchange dialysis membrane stack.

[0085] The cation exchange dialysis was carried out for 12.7 h, with a sodium glutamate conversion rate of 96.7% and a sodium ion membrane flux of 0.88 mol / m. 2 / h. Compared to single-stage batch processing, the six-stage countercurrent processing method, under the same sodium sulfate solution and operating conditions, increased the monosodium glutamate conversion rate by 37%.

[0086] Example 14

[0087] Monosodium glutamate is prepared using a four-stage countercurrent process, such as... Figure 10 As shown, the cation exchange dialysis device is configured as four identical plate-and-frame cation exchange dialysis membrane stacks, each stack being a single stage, and each stack being the same as in Example 1. The salt chambers of the four membrane stacks are connected in series, and the alkali chambers of the four membrane stacks are connected in series.

[0088] 900 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 100 g / L was introduced into the salt chamber of the first-stage plate-and-frame cation exchange dialysis membrane stack. The ammonium ion concentration was 12.4 g / L. 900 mL of sodium carbonate solution, with a total sodium ion content 1.1 times the initial total glutamic acid ion content in the fermentation broth, was introduced into the alkali chamber of the fourth-stage plate-and-frame cation exchange dialysis membrane stack as the replacement medium. Aeration was then introduced into the alkali chamber of the fourth-stage cation exchange dialysis membrane stack. Figure 2 As shown, the linear velocity of the feed solution in each chamber within the membrane stack is 3 cm / s, and the temperature of the feed solution in each chamber is 50-55℃. The glutamic acid fermentation broth sequentially passes through the salt chambers of the first to fourth stage plate-and-frame cation exchange dialysis membrane stacks, while the sodium carbonate solution sequentially passes through the alkali chambers of the fourth to first stage plate-and-frame cation exchange dialysis membrane stacks for cation exchange dialysis. Sodium glutamate is obtained in the salt chamber of the fourth stage plate-and-frame cation exchange dialysis membrane stack, and ammonium salt is obtained in the alkali chamber of the first stage plate-and-frame cation exchange dialysis membrane stack.

[0089] The cation exchange dialysis was performed for 3.2 hours, achieving a sodium glutamate conversion rate of 95.9% and a sodium ion membrane flux of 1.05 mol / m³. 2 / h. Compared to single-stage batch processing, the four-stage countercurrent processing method increases the monosodium glutamate conversion rate by 5.2% under the same sodium carbonate solution and operating conditions.

Claims

1. A method for preparing monosodium glutamate directly from glutamate fermentation broth using cation exchange dialysis, the method comprising: The glutamic acid fermentation broth is passed through a cation exchange dialysis device and subjected to cation exchange dialysis of ammonium ions and sodium ions with a sodium ion aqueous solution, and finally sodium glutamate and ammonia or ammonium salt are obtained. The main component of the glutamic acid fermentation broth is ammonium glutamate. The cation exchange dialysis device includes one or more cation exchange dialysis components connected in series and / or in parallel. The cation exchange dialysis assembly includes a cation exchange dialysis membrane and a salt chamber and an alkali chamber separated by the cation exchange dialysis membrane. The glutamic acid fermentation broth is passed into the salt chamber, and the sodium ion aqueous solution is passed into the alkali chamber. The ammonium ions in the glutamic acid fermentation broth passed into the salt chamber and the sodium ions in the sodium ion aqueous solution passed into the alkali chamber undergo ion exchange through the cation exchange dialysis membrane. That is, the ammonium ions migrate across the cation exchange dialysis membrane into the alkali chamber, and the sodium ions migrate across the cation exchange dialysis membrane into the salt chamber. Thus, sodium glutamate is obtained in the salt chamber, and ammonia or ammonium salt is obtained in the alkali chamber. The sum of the initial total amount of sodium ions in the sodium ion aqueous solution is greater than the initial total amount of glutamate ions in the glutamate fermentation broth.

2. The method according to claim 1, characterized in that, The number of the plurality of cation exchange dialysis components is two, three, four, five, or six.

3. The method according to claim 1, characterized in that, The cation exchange dialysis module is a plate-and-frame cation exchange dialysis membrane stack, a tubular cation exchange dialysis membrane module, or a spiral wound cation exchange dialysis membrane module.

4. The method according to claim 1, characterized in that, The initial concentration of the glutamic acid fermentation broth is 50-350 g / L, calculated as glutamic acid.

5. The method according to claim 1, characterized in that, The sodium ion aqueous solution refers to a neutral to alkaline aqueous solution containing sodium ions, including but not limited to aqueous solutions of sodium hydroxide, sodium sulfate, sodium chloride, sodium carbonate, or sodium bicarbonate.

6. The method according to claim 5, characterized in that, When the sodium ion aqueous solution is an alkaline sodium ion-containing aqueous solution, air is blown into the alkaline chamber of the cation exchange dialysis device during cation exchange dialysis.

7. The method according to claim 1, characterized in that, The linear velocity of the feed liquid in the cation exchange dialysis device is 0.5-7 cm / s; the temperature of the cation exchange dialysis is 20-60℃.

8. The method according to claim 1, characterized in that, The cation exchange dialysis process includes replacing the sodium ion aqueous solution with a fresh solution. In the aforementioned method of replacing the sodium ion aqueous solution with fresh sodium ion aqueous solution, the sum of the initial total amount of sodium ions in all fresh sodium ion aqueous solutions is greater than the initial total amount of glutamate ions in the glutamate fermentation broth.

9. The method according to claim 1, characterized in that, The cation exchange dialysis adopts a multi-stage countercurrent treatment method; The multi-stage countercurrent treatment method involves configuring the cation exchange dialysis device into multiple cation exchange dialysis modules. Each cation exchange dialysis module is a stage, including a cation exchange dialysis membrane and salt and alkali chambers separated by the cation exchange dialysis membrane. The salt chambers of multiple stages of cation exchange dialysis modules are connected in series, and the alkali chambers of multiple stages of cation exchange dialysis modules are connected in series. The initial glutamic acid fermentation broth is passed into the salt chamber of the first-stage cation exchange dialysis module, and the initial sodium ion aqueous solution is passed into the alkali chamber of the last-stage cation exchange dialysis module. The glutamic acid fermentation broth passes through the salt chambers of each stage of cation exchange dialysis module sequentially from the first stage to the last stage, and undergoes cation exchange dialysis with the sodium ion aqueous solution containing partially recovered ammonium from each stage of cation exchange dialysis module. Sodium glutamate is obtained in the salt chamber of the last-stage cation exchange dialysis module. The sodium ion aqueous solution passes through the alkali chambers of each stage of cation exchange dialysis module sequentially from the last stage to the first stage, and ammonia or ammonium salt is obtained in the alkali chamber of the first-stage cation exchange dialysis module.

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