Method for separating mannitol and sodium gluconate

Abstract

The invention relates to a method for separating mannitol and sodium gluconate in mannitol fermentation liquor, which comprises the following steps: the fermentation liquor firstly passes through a strongly acidic cation exchange column, sodium ions are adsorbed on resin of the cation exchange column when the fermentation liquor passes through the cation exchange column, and then the fermentation liquor passes through a carbon column for decoloration; the mannitol is separated from an anion exchange column by controlling the discharge conductivity and the pH value through the alkalescent anion exchange column; and analyzing the alkalescent anion exchange column by using a NaOH solution to obtain sodium gluconate, and finally separating the mannitol from the sodium gluconate in the mannitol fermentation liquor. Wherein the anion resin column and the anion resin column can be regenerated and recycled after being used, so that the production cost is reduced. The yield of the separated mannitol is 93% or above, and a good separation effect is achieved.

Description

Technical Field

[0001] The invention relates to a method for separating mannitol and sodium gluconate in mannitol fermentation broth, belonging to the technical field of biological fermentation. Background Art

[0002] Mannitol, also known as mannitol, is a natural six-carbon sugar alcohol. It is an isomer of sorbitol and is widely used in the food, medical and chemical industries.

[0003] At present, the production methods of mannitol include extraction, chemical synthesis, enzyme conversion and microbial fermentation. Among them, the chemical synthesis method has been the main production method of mannitol for a long time in the past. Its principle is: fructose and glucose are mixed, placed in a high temperature and high pressure environment, and Raney nickel is used as a catalyst to obtain mannitol through hydrogenation. However, due to the poor selectivity of the Raney nickel catalyst, the mannitol prepared by this method will have more sorbitol by-products, which leads to the low efficiency of the chemical synthesis method for producing mannitol and the production cost is also difficult to control. The main steps of the enzymatic conversion method for producing mannitol include glucose isomerization, fructose conversion to mannitol, Purification and crystallization: The purpose of purification and crystallization is to obtain a high-purity mannitol product.

[0004] Purification is the process of removing impurities and pigments from the obtained mannitol, while crystallization is the process of precipitating mannitol from the solution in the form of crystals for easy separation and collection. The composition of mannitol fermentation broth is complex, mainly including mycelial protein, sodium gluconate, divalent metals and pigments.

[0005] There is currently no better way to further separate mannitol and sodium gluconate in the mannitol fermentation broth produced by the enzyme conversion method. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides a method for separating mannitol and sodium gluconate in mannitol fermentation broth.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: A method for separating mannitol and sodium gluconate comprises the following steps: (1) filtering the mannitol fermentation broth through an ultrafiltration membrane to remove mycelial protein, and ultrafiltration to obtain a preliminarily treated fermentation broth; (2) The fermentation liquid enters the strong acid cation exchange column and controls the feed flow rate to 10-30m 3 / h, the sodium ion content of the cation exchange column is 10-100ppm, and the pH value is 1-3; when the pH value of the cation exchange resin output is 1-4, the material is collected; (3) The fermentation liquid enters the carbon column at a flow rate of 10-30 m³ / h and circulates for decolorization until the light transmittance of the fermentation liquid is measured to be above 90%; (4) The fermentation liquid after decolorization is 5-30m 3 / h flow into the weakly alkaline anion exchange column, top-washed with water 3 times the volume of the exchange column, and the material flowing out of the outlet of the anion exchange column is mannitol; (5) using a 6% NaOH solution to analyze the weakly alkaline anion exchange column to obtain a sodium gluconate solution; (6) During the analysis process, the conductivity of the washed material is detected. When the conductivity suddenly rises to 500-1000 us / cm, sodium gluconate is collected. When the pH of the washed material is greater than 14 and the conductivity is lower than 200 us / cm, the collection of the material is stopped to obtain the separated sodium gluconate solution.

[0008] Furthermore, the fermentation broth preliminarily treated in step (1) contains 100-200 g / L sodium gluconate and 100-170 g / L mannitol; After all the fermentation liquid after decolorization in step (4) passes through the anion exchange column, the anion exchange column is rinsed with water until the conductivity of the fermentation liquid is 200-500 us / cm, and the collection of the material is stopped. The pH value of the obtained mannitol is 6-8; The amount of NaOH solution used in step (5) is 3 times the volume of the anion exchange column, and the flow rate of the NaOH solution is 5-20m³ / h.

[0009] (1) The method for separating mannitol and sodium gluconate from mannitol fermentation broth of the present invention comprises the following steps: the fermentation broth first passes through a strongly acidic cation exchange column, during which sodium ions are adsorbed on the resin of the cation exchange column, and then passes through a carbon column for decolorization; the fermentation broth then passes through a weakly alkaline anion exchange column, and the discharge conductivity and pH value are controlled to separate mannitol from the anion exchange column; the weakly alkaline anion exchange column is resolved by a NaOH solution to obtain sodium gluconate, and finally the mannitol and sodium gluconate in the mannitol fermentation broth are separated.

[0010] (2) The mannose yield after separation is over 93%, and the purity after concentration and crystallization is over 99%, achieving a good separation effect and can be applied to large-scale production.

[0011] (3) Anion resin columns can be regenerated with sodium hydroxide solution. Anion resin columns can be regenerated with hydrochloric acid solution and can be recycled, greatly reducing production costs. DETAILED DESCRIPTION

[0012] The specific implementation modes of the present invention are further described in detail below in conjunction with the embodiments.

[0013] Example 1 A method for separating mannitol and sodium gluconate comprises the following steps: (1) filtering the mannitol fermentation broth through an ultrafiltration membrane to remove mycelial protein, and the ultrafiltered fermentation broth contains 100-200 g / L of sodium gluconate and 100-170 g / L of mannitol; (2) The fermentation liquid enters the strong acid cation exchange column with a feed flow rate of 10-30m 3 / h, control the sodium ion content of the cation exchange column to 10-100ppm, and the pH value to 1-3 (when the fermentation liquid passes through the cation exchange column, the sodium ions in the solution are adsorbed on the cation exchange column resin, and the fermentation liquid changes from neutral to acidic); when the pH of the cation exchange resin output is 1-4, start collecting the material (a mixture of gluconic acid, mannitol and water), and use 3 times the volume of the cation exchange column to wash the top, and the pH of the mixed cation exchange liquid is 1-3; (3) The fermentation liquid enters the carbon column at a flow rate of 10-30m³ / h for cyclic decolorization until the light transmittance of the fermentation liquid is measured to be above 90% and there are no obvious impurities; (4) The fermentation liquid after decolorization is 5-30m 3 / h flow into the weakly basic anion exchange column, and rinsed from the top with water 3 times the volume of the weakly basic anion exchange column, and the feed liquid flowing out of the outlet of the anion exchange column is a mannitol solution; After all the decolorized fermentation liquid passes through the anion exchange column, the anion exchange column is rinsed with water until the conductivity of the fermentation liquid is 200-500us / cm, and then the collection of the material is stopped. The pH value of the obtained mannitol is 6-8; At this point, most of the mannitol in the fermentation broth has been separated, and the mannitol yield is over 93%.

[0014] (5) A 6% NaOH solution is used to analyze the weak alkaline anion exchange column to obtain sodium gluconate, wherein the amount of NaOH solution used is 3 times the volume of the anion exchange column, and the flow rate of the NaOH solution is controlled to be 5-20 m³ / h; During the analysis process, the conductivity of the washed material was detected. When the conductivity suddenly rose to 500-1000us / cm, sodium gluconate was collected. When the pH of the washed material was > 14 and the conductivity was below 200us / cm, the collection of the material was stopped. At this time, all the sodium gluconate had been analyzed, and the content of sodium gluconate was 76g / L.

[0015] The anion resin column in the present invention can be regenerated by using a 6% sodium hydroxide solution, and the anion resin column can be regenerated by using a 6% hydrochloric acid solution.

Claims

1. A method for separating mannitol and sodium gluconate, characterized in that: The method comprises the following steps: (1) filtering the mannitol fermentation broth through an ultrafiltration membrane to remove mycelial protein, and ultrafiltration to obtain a preliminarily treated fermentation broth; (2) The fermentation liquid enters the strong acid cation exchange column and controls the feed flow rate to 10-30m 3 / h, the sodium ion content of the cation exchange column is 10-100ppm, and the pH value is 1-3; when the pH value of the cation exchange resin output is 1-4, the material is collected; (3) The fermentation liquid enters the carbon column at a flow rate of 10-30 m³ / h and circulates for decolorization until the light transmittance of the fermentation liquid is measured to be above 90%; (4) The fermentation liquid after decolorization is 5-30m 3 / h flow into the weakly alkaline anion exchange column, top-washed with water 3 times the volume of the exchange column, and the material flowing out of the outlet of the anion exchange column is mannitol; (5) using a 6% NaOH solution to analyze the weakly alkaline anion exchange column to obtain a sodium gluconate solution; (6) During the analysis process, the conductivity of the washed material is detected. When the conductivity suddenly rises to 500-1000 us / cm, sodium gluconate is collected. When the pH of the washed material is greater than 14 and the conductivity is lower than 200 us / cm, the collection of the material is stopped to obtain the separated sodium gluconate solution.

2. The separation method according to claim 1, characterized in that The fermentation liquid preliminarily treated in step (1) contains 100-200 g / L of sodium gluconate and 100-170 g / L of mannitol.

3. The separation method according to claim 1, characterized in that After all the decolorized fermentation liquid in step (4) passes through the anion exchange column, the anion exchange column is rinsed with water until the conductivity of the fermentation liquid is 200-500 us / cm, and then the collection of the material is stopped. The pH value of the obtained mannitol is 6-8.

4. The separation method according to claim 1, characterized in that The amount of NaOH solution used in step (5) is 3 times the volume of the anion exchange column, and the flow rate of the NaOH solution is 5-20m³ / h.