WO2011047634A1 - Method for preparing citric acid - Google Patents
Method for preparing citric acid Download PDFInfo
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- WO2011047634A1 WO2011047634A1 PCT/CN2010/077992 CN2010077992W WO2011047634A1 WO 2011047634 A1 WO2011047634 A1 WO 2011047634A1 CN 2010077992 W CN2010077992 W CN 2010077992W WO 2011047634 A1 WO2011047634 A1 WO 2011047634A1
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- Prior art keywords
- citric acid
- calcium
- liquid
- citrate
- solid
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/02—Preparation of carboxylic acids or their salts, halides or anhydrides from salts of carboxylic acids
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/41—Preparation of salts of carboxylic acids
- C07C51/412—Preparation of salts of carboxylic acids by conversion of the acids, their salts, esters or anhydrides with the same carboxylic acid part
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
Definitions
- the invention relates to a method for preparing citric acid.
- Citric acid as organic acid is widely applicable in beverage, food, medicine and other industries.
- the conventional method for preparing citric acid comprises the following steps: pre-processing and fermenting materials to obtain fermentation liquid; further purifying citric acid from the fermentation liquid; and post-processing.
- the methods for purifying citric acid from the fermentation liquid in the prior art include the calcium salt method, the hydrogen/calcium method and the chromatography method. Since the step for pre-processing materials on the basis of the chromatography method is complicated, and the investment on auxiliary facilities is larger, the conventional calcium salt method or hydrogen/calcium method is generally used for purifying citric acid obtained through fermentation.
- CN101117315A discloses a method for producing citric acid, which comprises the following steps:
- the invention intends to overcome the defect that the yield of citric acid obtained by the method for preparing citric acid in the prior art is low and provides a method for preparing citric acid with a high yield.
- the method of CN101117315A comprises the following steps: firstly, neutralizing citric acid into calcium citrate; then carrying out reaction between the calcium citrate and the mycelium-removed liquid of citric acid to generate calcium hydrogen citrate and/or calcium dihydrogen citrate; then, carrying out solid-liquid separation, and washing the solid phase; carrying out acidolysis on the solid phase to obtain citric acid; and recycling the liquid phase to step 1).
- step 1) Because the liquid phase contains a large amount of water and a small part of dissolved calcium hydrogen citrate, by recycling the liquid phase to step 1) for processing again, the processing load of step 1) can be increased on one hand, and on the other hand, after a large amount of liquid phase is recycled to the fermentation liquid of citric acid in step 1), the concentration of the fermentation liquid of citric acid is reduced, thus reducing the reaction rate, and since the amount of the liquid phase recycled to step 1) is large, the dissolution loss of calcium citrate in the separated wastewater can be greatly increased correspondingly after the calcium citrate is generated through the reaction in the step, thus effecting the yield of citric acid.
- the invention provides a method for preparing citric acid, which comprises the following steps:
- step (2) subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis to obtain citric acid;
- step (3) contacting and reacting the first liquid phase obtained in step (1) with calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the first liquid phase can be converted into calcium citrate, subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium citrate and a second liquid phase, and recycling the solid calcium citrate to step (1) to contact and react the solid calcium citrate with the fermentation liquid of citric acid and calcium carbonate and/or calcium hydroxide.
- the method of the invention for preparing citric acid can achieve the purpose of effectively increasing the yield of citric acid through the following steps: carrying out solid-liquid separation on calcium hydrogen citrate; carrying out the reaction between the liquid phase and calcium carbonate and/or calcium hydroxide to obtain calcium citrate; and recycling the calcium citrate to step (1) and repeating the operations in step (1).
- the invention can increase the yield of citric acid and greatly simplify the operating steps.
- the method for preparing citric acid comprises the following steps:
- step (2) subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis to obtain citric acid;
- step (3) contacting and reacting the first liquid phase obtained in step (1) with calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the first liquid phase can be converted into calcium citrate, subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium citrate and a second liquid phase, and recycling the solid calcium citrate to step (1) to contact and react the solid calcium citrate with the fermentation liquid of citric acid and calcium carbonate and/or calcium hydroxide.
- the conditions for the contact and reaction between the fermentation liquid of citric acid and calcium carbonate and/or calcium hydroxide are as follows: the pH value at the end point of the reaction is 2.5 to 3.5, preferably 2.9 to 3.1; the reaction temperature is 75 to 85 DEG C; and the reaction time is 4 to 7 hours.
- the conditions for the contact and reaction between the first liquid phase and calcium carbonate and/or calcium hydroxide can also allow the conversion of a small amount of non-reacted citric acid in the first liquid into calcium citrate.
- the method further comprises the following steps: washing calcium hydrogen citrate to remove the residual fermentation liquid of citric acid before carrying out the acidolysis on the solid calcium hydrogen citrate obtained in step (1); and carrying out contact and reaction between the mixture of the obtained washing liquid of calcium hydrogen citrate and the first liquid phase obtained in step (1) and calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the washing liquid of calcium hydrogen citrate, and the calcium hydrogen citrate dissolved in the first liquid phase and the residual fermentation liquid of citric acid can be converted into calcium citrate.
- the conditions for the contact and reaction between the first liquid phase and the calcium carbonate and/or calcium hydroxide can also allow the conversion of a small amount of non-reacted citric acid in the first liquid into calcium citrate.
- the washing method adopts the method and conditions well known to those skilled in the art, e.g., the method for washing the calcium hydrogen citrate comprises the method of leaching or immersing by water; and the washing method and condition can be any as long as the residual fermentation liquid is washed off.
- the amount of the washing water preferably is 10 volume % to 35 volume % of the fermentation liquid, and the washing temperature is generally 70 to 95 DEG C, preferably 80 to 90 DEG C.
- the method and conditions for carrying out acidolysis on calcium hydrogen citrate are well known to those skilled in the art, e.g., in step (2), the method for carrying out acidolysis on the solid calcium hydrogen citrate obtained in step (1) comprises the following step: allowing calcium hydrogen citrate to contact with the acid solution, wherein the conditions of acidolysis are as follows: the pH value is 1.5 to 1.8; the temperature of the acidolysis is 70 to 95 DEG C, preferably 80 to 90 DEG C; the time of the acidolysis is 40 to 60 minutes; the acid for acidolysis adopts various acids well known to those skilled in the art, wherein the concentrated sulfuric acid with the mass percentage of 98% is generally adopted.
- the conditions for the contact and reaction between the first liquid phase obtained in step (1) and calcium carbonate and/or calcium hydroxide are as follows: the pH value at the end point of the reaction is 4.5 to 5.5, preferably 4.5 to 5.0; the reaction temperature is 60 to 80 DEG C, preferably 70 to 75 DEG C; and the reaction time is 30 to 60 minutes, preferably 40 to 60 minutes.
- the method further comprises the following step: carrying out the wastewater treatment on the second liquid phase obtained in step (3), wherein the specific method and conditions for treating the wastewater can be referred to the method in CN101293716A.
- the method for preparing the fermentation liquid of citric acid may adopt various preparation methods well known to those skilled in the art, e.g., the preparation method comprises the following steps: grinding corn materials; liquefying the ground product; and fermenting the liquefied product, wherein the content of citric acid in the fermentation liquid is generally lOOg to 120g per liter.
- the method further comprises the following step: carrying out the processes of ion-exchange, concentration, crystallization and drying on the citric acid obtained in step (2), wherein the specific method and conditions for the processes of ion-exchange, concentration, crystallization and drying are well known to those skilled in the art.
- the acidolysis solution also contains a small amount of Ca 2+ , Mg 2+ ,
- the ion exchange based on absorption exchange can be achieved by activated carbon, cation exchange resin and anion exchange resin to remove the pigments, Ca 2+ , Mg 2+ , Fe 3+ , CI " and other harmful ions from the coarse solution of citric acid and obtain the refined solution of citric acid, wherein the parameter indexes for the ion exchange process are as follows: the light transmittance of the depigmented solution is higher than 96%; the light transmittance of the ion exchange liquid is higher than 96.5%; the Fe 3+ ion content of the ion exchange liquid is lower than 4ppm; the CI " ion content of the ion exchange liquid is lower than 4ppm; and the acidity of the ion exchange liquid is approximately 35%.
- the method for concentration, crystallization and drying is achieved by the following steps: vaporizing and discharging part of water in the citric acid liquid having lower concentration by heating; converting the citric acid liquid (solution) into a solid-liquid suspension under certain conditions; separating the crystal particles of citric acid from mother liquid; and drying the crystal particles of citric acid to obtain the citric acid (citric acid monohydrate) having higher concentration or the crystal particles of citric acid (anhydrous), wherein the temperatures of first-effect, double-effect and triple-effect concentration are 105 DEG C, 90 DEG C and 70 DEG C respectively, the first-effect, double-effect and triple-effect vacuum degrees are -lOkPa, -40kPa and -90kPa respectively; the flow rate of feeding is approximately 5.5M /H in the production line of anhydrous citric acid for obtaining the crystal particles of citric acid and anhydrous mother liquid, particularly, the water on the surface of citric acid is vaporized by a drier (45 DEG C in section one
- the fermentation liquid of citric acid in the following examples is prepared by: grinding 0.872kg of corn by an SFSP-series hammer mill to obtain 0.871kg of ground product with the average particle diameter of 2mm (by an Accu-Sizer TM 780 optical particle sizer, PSS company, US); mixing the ground product with amylase, and carrying out the spraying liquefaction for 40 to 60 minutes, wherein the pH value of enzymolysis is maintained at 5.7 to 6.2, the temperature for the primary liquefaction is 83+1 DEG C, and the temperature for the secondary liquefaction is controlled to 93+1 DEG C; adding alpha-amylase with the activity higher than or equal to 2,000u/ml (purchased from Novozymes company) in the ratio of 0.7g per each kilogram of corn powder; reducing the temperature to 38 DEG C, and inoculating aspergillus niger 18g/L (fermentation liquor); stirring and culturing the obtained mixture at 37 DEG C in a fermentation tank
- the example is used for describing the method of the invention for preparing citric acid.
- step (3) adding calcium carbonate to 5.54L of mixture of the first liquid phase and the washing liquid obtained in step (1), stopping adding the calcium carbonate when the pH value of the mixture at the end point is controlled to 5; reacting for 45 minutes; then, carrying out solid-liquid separation to obtain 29.3g of solid calcium citrate and a second liquid phase; returning the calcium citrate to step (1) and repeating the operations in step (1); and carrying out the wastewater treatment on the second liquid phase, wherein after the operation cycle is stable, 534.61g of citric acid in total can be obtained in each time of operation; and the yield of citric acid is 97.2% according to the following formula.
- the yield of citric acid (%) the amount of citric acid obtained through acidolysis x 100% / the content of citric acid in the fermentation liquid of citric acid. Comparative example 1
- the comparative example is used for describing the comparative method for preparing citric acid
- step (2) slowly adding the fermentation liquid of citric acid to 2.59L of the calcium citrate slurry obtained in step (1) at 85 DEG C, stop adding the fermentation liquid of citric acid when the pH value of the mixture is controlled to 3.1; carrying out the solid-liquid separation on the mixture obtained through the reaction; returning 6.43L of the liquid phase to step (1), and repeating the operations in step (1); and washing the separated solid phase with water at 50 DEG C for later use, wherein the solid phase is calcium hydrogen citrate and/or calcium dihydrogen citrate;
- step (3) mixing 621.28g of the washed solid phase separated in step (2) and 264.72g of concentrated sulfuric acid (with the concentration of sulfuric acid being 98wt ); controlling the pH value of the mixture to 1.8; reacting for 50 minutes; and carrying out the acidolysis to obtain citric acid and calcium sulfate;
- the yield of citric acid is 94.3% according to the formula in Example 1.
- the amount of the mixture of the first liquid phase and the washing liquid obtained in step (1) is 5.54L
- the amount of calcium citrate returned to step (1) is only 29.3g
- the amount of the liquid phase returned to step (1) in the comparative example is as high as 6.43L.
- a large amount of liquid phase returned each time can increase the processing load of step (1) and reduce the reaction rate on one hand, and on the other hand, after the liquid phase in which a large amount of calcium hydrogen citrate and/or calcium dihydrogen citrate is dissolved, the amount of the calcium citrate of solution loss and small part of calcium hydrogen citrate and calcium dihydrogen citrate in the separated wastewater can be greatly increased, thus increasing the loss of citric acid and effecting the yield thereof.
- the example is used for describing the method of the invention for preparing citric acid.
- step (2) mixing the calcium hydrogen citrate obtained in step (1) and 258.37g of concentrated sulfuric acid (with the concentration of sulfuric acid being 98wt ) at 75 DEG C; reacting for 40 minutes with the pH value of the mixture being controlled to 1.5, to obtain 1.33L of citric acid liquid;
- step (3) adding calcium carbonate to 4.45L of mixture of the first liquid phase obtained in step (1), stop adding the calcium carbonate when the pH value of the mixture at the end point is controlled to 4.5; reacting for 40 minutes; then, carrying out the solid-liquid separation to obtain 39.68g of solid calcium citrate and a second liquid phase; returning the calcium citrate to step (1) and repeating the operations in step (1); and carrying out the wastewater treatment on the second liquid phase, wherein after the operation cycle is stable, 536.8g of citric acid in total can be obtained in each time of operation; and the yield of citric acid is 97.6% according to the formula in Example 1.
- the example is used for describing the method of the invention for preparing citric acid.
- step (2) mixing the calcium hydrogen citrate obtained in step (1) and 264.89g of concentrated sulfuric acid (with the concentration of sulfuric acid being 98wt%) at 90 DEG C; reacting for 45 minutes with the pH value of the mixture being controlled to 1.6, to obtain 1.37L of citric acid liquid;
- step (1) (3) adding calcium carbonate to 4.53L of mixture of the first liquid phase obtained in step (1), stop adding the calcium carbonate when the pH value of the mixture at the end point is controlled to 5.3; reacting for 50 minutes; then, carrying out the solid-liquid separation to obtain 21.98g of solid calcium citrate and a second liquid phase; returning the calcium citrate to step (1) and repeating the operations in step (1); and carrying out the wastewater treatment on the second liquid phase, wherein after the operation cycle is stable, 535.9 lg of citric acid in total can be obtained in each time of operation; and the yield of citric acid is 97.4% according to the formula in Example 1.
- the example is used for describing the method of the invention for preparing citric acid.
- the citric acid is prepared by the same method as Example 1, except that the consumption of washing water is 0.75L in step (1); 613.36g of calcium hydrogen citrate and 5.29L of mixture of the first liquid phase and the washing liquid are obtained; and after the operation cycle is stable, 533.52g of citric acid in total can be obtained in each time of operation and the yield of citric acid is 97.0%.
- the example is used for describing the method of the invention for preparing citric acid.
- the citric acid is prepared by the same method as Example 1, except that the consumption of washing water is 1.5L in step (1); 613.36g of calcium hydrogen citrate and 6.04L of mixture of the first liquid phase and the washing liquid are obtained; and after the operation cycle is stable, 532.42g of citric acid in total can be obtained in each time of operation and the yield of citric acid is 96.8%.
- the example is used for describing the method of the invention for preparing citric acid.
- the citric acid is prepared by the same method as Example 1, except that the consumption of washing water is 2L in step (1); 613.36g of calcium hydrogen citrate and 6.54L of mixture of the first liquid phase and the washing liquid are obtained; and after the operation cycle is stable, 528g of citric acid in total can be obtained in each time of operation and the yield of citric acid is 96.0%.
- Example 7
- the example is used for describing the method of the invention for preparing citric acid.
- the citric acid is prepared by the same method as Example 1, except that the consumption of washing water is 0.35L in step (1); 613.36g of calcium hydrogen citrate and 4.89L of mixture of the first liquid phase and the washing liquid are obtained; and after the operation cycle is stable, 529.65g of citric acid in total can be obtained in each time of operation and the yield of citric acid is 96.3%.
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Abstract
Provided is a method for preparing citric acid comprising the following steps: (1) contacting and reacting the fermentation liquid of citric acid with calcium carbonate and/or calcium hydroxide under the condition that the citric acid in the fermentation liquid can be converted into calcium hydrogen citrate, and subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium hydrogen citrate and a first liquid phase; (2) subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis to obtain citric acid; (3) contacting and reacting the first liquid phase obtained in step (1) with calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the first liquid phase can be converted into calcium citrate, subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium citrate, and recycling the solid calcium citrate to step (1).
Description
Method for preparing citric acid
Technical field:
The invention relates to a method for preparing citric acid.
Background art:
Citric acid as organic acid is widely applicable in beverage, food, medicine and other industries. The conventional method for preparing citric acid comprises the following steps: pre-processing and fermenting materials to obtain fermentation liquid; further purifying citric acid from the fermentation liquid; and post-processing. The methods for purifying citric acid from the fermentation liquid in the prior art include the calcium salt method, the hydrogen/calcium method and the chromatography method. Since the step for pre-processing materials on the basis of the chromatography method is complicated, and the investment on auxiliary facilities is larger, the conventional calcium salt method or hydrogen/calcium method is generally used for purifying citric acid obtained through fermentation.
For example, CN101117315A discloses a method for producing citric acid, which comprises the following steps:
1) firstly, adding calcium carbonate and/or calcium hydroxide to the mycelium-removed liquid of citric acid to carry out reaction with the pH value at the end point thereof being 3 to 9, and separating wastewater to obtain calcium citrate;
2) carrying out reaction between the calcium citrate and the mycelium-removed liquid of citric acid and adjusting the pH value to 1.5 to 6, to generate calcium hydrogen citrate and/or calcium dihydrogen citrate;
3) then, carrying out solid-liquid separation, washing the solid phase, recycling the liquid phase to step 1), and carrying out acidolysis on the solid phase to generate citric acid and calcium salts;
4) carrying out solid-liquid separation, washing the solid phase, and processing the liquid phase to obtain the product of citric acid.
However, the yield of citric acid prepared by the existing hydrogen/calcium method is low.
Summary of the Invention
The invention intends to overcome the defect that the yield of citric acid obtained by the method for preparing citric acid in the prior art is low and provides a method for preparing citric acid with a high yield.
The present inventors found that, the method of CN101117315A comprises the following steps: firstly, neutralizing citric acid into calcium citrate; then carrying out reaction between the calcium citrate and the mycelium-removed liquid of citric acid to generate calcium hydrogen citrate and/or calcium dihydrogen citrate; then, carrying out solid-liquid separation, and washing the solid phase; carrying out acidolysis on the solid phase to obtain citric acid; and recycling the liquid phase to step 1). Because the liquid phase contains a large amount of water and a small part of dissolved calcium hydrogen citrate, by recycling the liquid phase to step 1) for processing again, the processing load of step 1) can be increased on one hand, and on the other hand, after a large amount of liquid phase is recycled to the fermentation liquid of citric acid in step 1), the concentration of the fermentation liquid of citric acid is reduced, thus reducing the reaction rate, and since the amount of the liquid phase recycled to step 1) is large, the dissolution loss of calcium citrate in the separated wastewater can be greatly increased correspondingly after the calcium citrate is generated through the reaction in the step, thus effecting the yield of citric acid.
The invention provides a method for preparing citric acid, which comprises the following steps:
(1) contacting and reacting the fermentation liquid of citric acid with calcium carbonate and/or calcium hydroxide under the condition that the citric acid in the fermentation liquid can be converted into calcium hydrogen citrate, and subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium hydrogen citrate and a first liquid phase;
(2) subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis to obtain citric acid;
(3) contacting and reacting the first liquid phase obtained in step (1) with calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the first liquid phase can be converted into calcium citrate, subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium citrate and a second liquid phase, and recycling the solid calcium citrate to step (1) to contact and react the solid calcium citrate with the fermentation liquid of citric acid
and calcium carbonate and/or calcium hydroxide.
Since the present inventors find out the reason that the yield of citric acid prepared by the existing calcium salt method is low through analysis, the method of the invention for preparing citric acid can achieve the purpose of effectively increasing the yield of citric acid through the following steps: carrying out solid-liquid separation on calcium hydrogen citrate; carrying out the reaction between the liquid phase and calcium carbonate and/or calcium hydroxide to obtain calcium citrate; and recycling the calcium citrate to step (1) and repeating the operations in step (1). Besides, by carrying out the one- step reaction to obtain calcium hydrogen citrate, the invention can increase the yield of citric acid and greatly simplify the operating steps.
Detailed Description:
According to the invention, the method for preparing citric acid comprises the following steps:
(1) contacting and reacting the fermentation liquid of citric acid with calcium carbonate and/or calcium hydroxide under the condition that the citric acid in the fermentation liquid can be converted into calcium hydrogen citrate, and subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium hydrogen citrate and a first liquid phase;
(2) subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis to obtain citric acid;
(3) contacting and reacting the first liquid phase obtained in step (1) with calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the first liquid phase can be converted into calcium citrate, subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium citrate and a second liquid phase, and recycling the solid calcium citrate to step (1) to contact and react the solid calcium citrate with the fermentation liquid of citric acid and calcium carbonate and/or calcium hydroxide.
According to the invention, the conditions for the contact and reaction between the fermentation liquid of citric acid and calcium carbonate and/or calcium hydroxide are as follows: the pH value at the end point of the reaction is 2.5 to 3.5, preferably 2.9 to 3.1; the reaction temperature is 75 to 85 DEG C; and the reaction time is 4 to 7 hours. Besides, the conditions for the contact and reaction between the first liquid phase and calcium carbonate and/or calcium hydroxide can also allow the conversion of a small
amount of non-reacted citric acid in the first liquid into calcium citrate.
According to the invention, the method further comprises the following steps: washing calcium hydrogen citrate to remove the residual fermentation liquid of citric acid before carrying out the acidolysis on the solid calcium hydrogen citrate obtained in step (1); and carrying out contact and reaction between the mixture of the obtained washing liquid of calcium hydrogen citrate and the first liquid phase obtained in step (1) and calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the washing liquid of calcium hydrogen citrate, and the calcium hydrogen citrate dissolved in the first liquid phase and the residual fermentation liquid of citric acid can be converted into calcium citrate. Besides, the conditions for the contact and reaction between the first liquid phase and the calcium carbonate and/or calcium hydroxide can also allow the conversion of a small amount of non-reacted citric acid in the first liquid into calcium citrate. The washing method adopts the method and conditions well known to those skilled in the art, e.g., the method for washing the calcium hydrogen citrate comprises the method of leaching or immersing by water; and the washing method and condition can be any as long as the residual fermentation liquid is washed off.
As the solubility of calcium hydrogen citrate in water is much higher than that of calcium citrate in water, the consumption of the washing water and the time for washing depend on that as much fermentation liquid as possible on the surface of calcium hydrogen citrate is removed in order to achieve higher yield of citric acid. The present invents found that, in order to achieve better balance between the yield and quality of citric acid (part of impurities on the surface of the crystal are removed), i.e., ensure that the residue on the surface is removed and reduce the loss caused by dissolution, the amount of the washing water preferably is 10 volume % to 35 volume % of the fermentation liquid, and the washing temperature is generally 70 to 95 DEG C, preferably 80 to 90 DEG C.
According to the invention, the method and conditions for carrying out acidolysis on calcium hydrogen citrate are well known to those skilled in the art, e.g., in step (2), the method for carrying out acidolysis on the solid calcium hydrogen citrate obtained in step (1) comprises the following step: allowing calcium hydrogen citrate to contact with the acid solution, wherein the conditions of acidolysis are as follows: the pH value is 1.5 to 1.8; the temperature of the acidolysis is 70 to 95 DEG C, preferably 80 to 90 DEG C; the time of the acidolysis is 40 to 60 minutes; the acid for acidolysis
adopts various acids well known to those skilled in the art, wherein the concentrated sulfuric acid with the mass percentage of 98% is generally adopted.
According to the invention, the conditions for the contact and reaction between the first liquid phase obtained in step (1) and calcium carbonate and/or calcium hydroxide are as follows: the pH value at the end point of the reaction is 4.5 to 5.5, preferably 4.5 to 5.0; the reaction temperature is 60 to 80 DEG C, preferably 70 to 75 DEG C; and the reaction time is 30 to 60 minutes, preferably 40 to 60 minutes.
According to the invention, the method further comprises the following step: carrying out the wastewater treatment on the second liquid phase obtained in step (3), wherein the specific method and conditions for treating the wastewater can be referred to the method in CN101293716A.
According to the invention, the method for preparing the fermentation liquid of citric acid may adopt various preparation methods well known to those skilled in the art, e.g., the preparation method comprises the following steps: grinding corn materials; liquefying the ground product; and fermenting the liquefied product, wherein the content of citric acid in the fermentation liquid is generally lOOg to 120g per liter. According to the invention, the method further comprises the following step: carrying out the processes of ion-exchange, concentration, crystallization and drying on the citric acid obtained in step (2), wherein the specific method and conditions for the processes of ion-exchange, concentration, crystallization and drying are well known to those skilled in the art.
Besides pigments, the acidolysis solution also contains a small amount of Ca2+, Mg2+,
Fe 3+ , CI -", S042-" and other impurity ions, the ion exchange based on absorption exchange can be achieved by activated carbon, cation exchange resin and anion exchange resin to remove the pigments, Ca2+, Mg2+, Fe3+, CI" and other harmful ions from the coarse solution of citric acid and obtain the refined solution of citric acid, wherein the parameter indexes for the ion exchange process are as follows: the light transmittance of the depigmented solution is higher than 96%; the light transmittance of the ion exchange liquid is higher than 96.5%; the Fe3+ ion content of the ion exchange liquid is lower than 4ppm; the CI" ion content of the ion exchange liquid is lower than 4ppm; and the acidity of the ion exchange liquid is approximately 35%. The method for concentration, crystallization and drying is achieved by the following steps: vaporizing and discharging part of water in the citric acid liquid having lower concentration by heating; converting the citric acid liquid (solution) into a solid-liquid
suspension under certain conditions; separating the crystal particles of citric acid from mother liquid; and drying the crystal particles of citric acid to obtain the citric acid (citric acid monohydrate) having higher concentration or the crystal particles of citric acid (anhydrous), wherein the temperatures of first-effect, double-effect and triple-effect concentration are 105 DEG C, 90 DEG C and 70 DEG C respectively, the first-effect, double-effect and triple-effect vacuum degrees are -lOkPa, -40kPa and -90kPa respectively; the flow rate of feeding is approximately 5.5M /H in the production line of anhydrous citric acid for obtaining the crystal particles of citric acid and anhydrous mother liquid, particularly, the water on the surface of citric acid is vaporized by a drier (45 DEG C in section one, 40 DEG C in section two, 20 DEG C in section three and approximately 7 DEG C in ice water) through air convection, so as to dry the crystal particles of citric acid; and the water on the surface of citric acid is vaporized by the drier (55 DEG C in section one, 45 DEG C in section two, 10 DEG C in section three and approximately 7 DEG C in ice water) through air convection, so as to dry the citric acid monohydrate.
The invention is further detailed described by the following examples.
The fermentation liquid of citric acid in the following examples is prepared by: grinding 0.872kg of corn by an SFSP-series hammer mill to obtain 0.871kg of ground product with the average particle diameter of 2mm (by an Accu-Sizer TM 780 optical particle sizer, PSS company, US); mixing the ground product with amylase, and carrying out the spraying liquefaction for 40 to 60 minutes, wherein the pH value of enzymolysis is maintained at 5.7 to 6.2, the temperature for the primary liquefaction is 83+1 DEG C, and the temperature for the secondary liquefaction is controlled to 93+1 DEG C; adding alpha-amylase with the activity higher than or equal to 2,000u/ml (purchased from Novozymes company) in the ratio of 0.7g per each kilogram of corn powder; reducing the temperature to 38 DEG C, and inoculating aspergillus niger 18g/L (fermentation liquor); stirring and culturing the obtained mixture at 37 DEG C in a fermentation tank for 65 hours to obtain the fermentation mixture; and filtering the fermentation mixture to obtain 5L of fermentation liquid of citric acid (the content of citric acid in each liter of fermentation liquid of citric acid is HOg.)
Example 1
The example is used for describing the method of the invention for preparing citric acid.
(1) adding calcium carbonate to 5L of fermentation liquid of citric acid at 75 DEG C; stopping adding the calcium carbonate when the pH value of the fermentation liquid at the end point is controlled to 2.95; reacting for 5 hours; then, carrying out the solid-liquid separation to obtain the solid calcium hydrogen citrate and 4.54L of a first liquid phase; washing the calcium hydrogen citrate to remove the residual fermentation liquid of citric acid, wherein the temperature of the washing water is 80 DEG C, and the consumption thereof is 1L; and obtaining 613.36g of calcium hydrogen citrate, and 5.54L of mixture of the first liquid phase and the washing liquid;
(2) mixing the washed calcium hydrogen citrate obtained in step (1) and 261.34g of concentrated sulfuric acid (with the concentration of sulfuric acid being 98wt%) at 85
DEG C; reacting for 50 minutes with the pH value of the mixture being controlled to 1.7, to obtain 1.35L of citric acid liquid (with the content of citric acid being 380g/L);
(3) adding calcium carbonate to 5.54L of mixture of the first liquid phase and the washing liquid obtained in step (1), stopping adding the calcium carbonate when the pH value of the mixture at the end point is controlled to 5; reacting for 45 minutes; then, carrying out solid-liquid separation to obtain 29.3g of solid calcium citrate and a second liquid phase; returning the calcium citrate to step (1) and repeating the operations in step (1); and carrying out the wastewater treatment on the second liquid phase, wherein after the operation cycle is stable, 534.61g of citric acid in total can be obtained in each time of operation; and the yield of citric acid is 97.2% according to the following formula.
The yield of citric acid (%) = the amount of citric acid obtained through acidolysis x 100% / the content of citric acid in the fermentation liquid of citric acid. Comparative example 1
The comparative example is used for describing the comparative method for preparing citric acid
(1) slowly adding calcium carbonate to 5L of fermentation liquid of citric acid (the content of citric acid in each liter of fermentation liquid of citric acid is HOg) at 75 DEG C, stop adding calcium carbonate when the pH value of the mixture is controlled to 4.8; reacting for 60 minutes; and filtering and separating to remove wastewater after the reaction liquid is layered, to obtain calcium citrate slurry.
(2) slowly adding the fermentation liquid of citric acid to 2.59L of the calcium citrate slurry obtained in step (1) at 85 DEG C, stop adding the fermentation liquid of citric
acid when the pH value of the mixture is controlled to 3.1; carrying out the solid-liquid separation on the mixture obtained through the reaction; returning 6.43L of the liquid phase to step (1), and repeating the operations in step (1); and washing the separated solid phase with water at 50 DEG C for later use, wherein the solid phase is calcium hydrogen citrate and/or calcium dihydrogen citrate;
(3) mixing 621.28g of the washed solid phase separated in step (2) and 264.72g of concentrated sulfuric acid (with the concentration of sulfuric acid being 98wt ); controlling the pH value of the mixture to 1.8; reacting for 50 minutes; and carrying out the acidolysis to obtain citric acid and calcium sulfate;
(4) filtering and separating to obtain citric acid; and washing the citric acid with water at 50 DEG C to obtain 1.365L (518.6g) of citric acid.
The yield of citric acid is 94.3% according to the formula in Example 1.
From the comparison between Example 1 and Comparative Example 1, it can be seen that:
In the condition that the feeding amount of the fermentation liquid of citric acid is identical, according to the method in Example 1, the amount of the mixture of the first liquid phase and the washing liquid obtained in step (1) is 5.54L, and the amount of calcium citrate returned to step (1) is only 29.3g, while the amount of the liquid phase returned to step (1) in the comparative example is as high as 6.43L. Accordingly, a large amount of liquid phase returned each time can increase the processing load of step (1) and reduce the reaction rate on one hand, and on the other hand, after the liquid phase in which a large amount of calcium hydrogen citrate and/or calcium dihydrogen citrate is dissolved, the amount of the calcium citrate of solution loss and small part of calcium hydrogen citrate and calcium dihydrogen citrate in the separated wastewater can be greatly increased, thus increasing the loss of citric acid and effecting the yield thereof.
Example 2
The example is used for describing the method of the invention for preparing citric acid.
(1) adding calcium carbonate to 5L of fermentation liquid of citric acid at 85 DEG C, stopping adding the calcium carbonate when the pH value of the fermentation liquid at the end point is controlled to 2.5; reacting for 4 hours; then, carrying out the solid-liquid separation to obtain 606.37g of solid calcium hydrogen citrate and 4.45L
of a first liquid phase;
(2) mixing the calcium hydrogen citrate obtained in step (1) and 258.37g of concentrated sulfuric acid (with the concentration of sulfuric acid being 98wt ) at 75 DEG C; reacting for 40 minutes with the pH value of the mixture being controlled to 1.5, to obtain 1.33L of citric acid liquid;
(3) adding calcium carbonate to 4.45L of mixture of the first liquid phase obtained in step (1), stop adding the calcium carbonate when the pH value of the mixture at the end point is controlled to 4.5; reacting for 40 minutes; then, carrying out the solid-liquid separation to obtain 39.68g of solid calcium citrate and a second liquid phase; returning the calcium citrate to step (1) and repeating the operations in step (1); and carrying out the wastewater treatment on the second liquid phase, wherein after the operation cycle is stable, 536.8g of citric acid in total can be obtained in each time of operation; and the yield of citric acid is 97.6% according to the formula in Example 1.
And finally, carrying out the processes of ion-exchange, concentration, crystallization and drying on the obtained citric acid to obtain the product of citric acid.
Example 3
The example is used for describing the method of the invention for preparing citric acid.
(1) adding calcium carbonate to 5L of fermentation liquid of citric acid at 80 DEG C, stopping adding the calcium carbonate when the pH value of the fermentation liquid at the end point is controlled to 3.5; reacting for 7 hours; then, carrying out the solid-liquid separation to obtain 621.67g of solid calcium hydrogen citrate and 4.53L of a first liquid phase;
(2) mixing the calcium hydrogen citrate obtained in step (1) and 264.89g of concentrated sulfuric acid (with the concentration of sulfuric acid being 98wt%) at 90 DEG C; reacting for 45 minutes with the pH value of the mixture being controlled to 1.6, to obtain 1.37L of citric acid liquid;
(3) adding calcium carbonate to 4.53L of mixture of the first liquid phase obtained in step (1), stop adding the calcium carbonate when the pH value of the mixture at the end point is controlled to 5.3; reacting for 50 minutes; then, carrying out the solid-liquid separation to obtain 21.98g of solid calcium citrate and a second liquid phase; returning the calcium citrate to step (1) and repeating the operations in step (1);
and carrying out the wastewater treatment on the second liquid phase, wherein after the operation cycle is stable, 535.9 lg of citric acid in total can be obtained in each time of operation; and the yield of citric acid is 97.4% according to the formula in Example 1.
And finally, carrying out the processes of ion-exchange, concentration, crystallization and drying on the obtained citric acid to obtain the product of citric acid.
Example 4
The example is used for describing the method of the invention for preparing citric acid.
The citric acid is prepared by the same method as Example 1, except that the consumption of washing water is 0.75L in step (1); 613.36g of calcium hydrogen citrate and 5.29L of mixture of the first liquid phase and the washing liquid are obtained; and after the operation cycle is stable, 533.52g of citric acid in total can be obtained in each time of operation and the yield of citric acid is 97.0%.
Example 5
The example is used for describing the method of the invention for preparing citric acid.
The citric acid is prepared by the same method as Example 1, except that the consumption of washing water is 1.5L in step (1); 613.36g of calcium hydrogen citrate and 6.04L of mixture of the first liquid phase and the washing liquid are obtained; and after the operation cycle is stable, 532.42g of citric acid in total can be obtained in each time of operation and the yield of citric acid is 96.8%.
Example 6
The example is used for describing the method of the invention for preparing citric acid.
The citric acid is prepared by the same method as Example 1, except that the consumption of washing water is 2L in step (1); 613.36g of calcium hydrogen citrate and 6.54L of mixture of the first liquid phase and the washing liquid are obtained; and after the operation cycle is stable, 528g of citric acid in total can be obtained in each time of operation and the yield of citric acid is 96.0%.
Example 7
The example is used for describing the method of the invention for preparing citric acid.
The citric acid is prepared by the same method as Example 1, except that the consumption of washing water is 0.35L in step (1); 613.36g of calcium hydrogen citrate and 4.89L of mixture of the first liquid phase and the washing liquid are obtained; and after the operation cycle is stable, 529.65g of citric acid in total can be obtained in each time of operation and the yield of citric acid is 96.3%.
Claims
1. A method for preparing citric acid comprising the following steps:
(1) contacting and reacting the fermentation liquid of citric acid with calcium carbonate and/or calcium hydroxide under the condition that the citric acid in the fermentation liquid can be converted into calcium hydrogen citrate, and subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium hydrogen citrate and a first liquid phase;
(2) subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis to obtain citric acid;
(3) contacting and reacting the first liquid phase obtained in step (1) with calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the first liquid phase can be converted into calcium citrate, subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium citrate and a second liquid phase, and recycling the solid calcium citrate to step (1) to contact and react the solid calcium citrate with the fermentation liquid of citric acid and calcium carbonate and/or calcium hydroxide.
2. The method according to claim 1, wherein in step (1), the condition for the contact and reaction between the fermentation liquid of citric acid and calcium carbonate and/or calcium hydroxide includes: the pH value at the end point of the reaction is 2.5 to 3.5; the reaction temperature is 75 to 85 °C ; and the reaction time is 4 to 7 hours.
3. The method according to claim 1 or 2, wherein the content of citric acid in the fermentation liquid of citric acid is lOOg to 120g per liter.
4. The method according to claim 1, wherein the method further comprises the following steps: washing calcium hydrogen citrate to remove the residual fermentation liquid of citric acid before subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis; and contacting and reacting the mixture of the obtained washing liquid of calcium hydrogen citrate and the first liquid phase obtained in step (1) with calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the washing liquid of calcium hydrogen citrate, and the calcium hydrogen citrate dissolved in the first liquid phase and the residual fermentation liquid of citric acid can be converted into calcium citrate.
5. The method according to claim 4, wherein the washing water is 10% to 35% vol of the fermentation liquid of citric acid; and the temperature of the washing water is 70 to 95 °C .
6. The method according to claim 1 or 4, wherein in step (2), the process for subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis to obtain citric acid comprises: allowing calcium hydrogen citrate to contact with an acid solution under the conditions that the pH value is 1.5 to 1.8, the temperature is 70 to 95 °C , and the time is 40 to 60 minutes.
7. The method according to claim 1 or 4, wherein in step (3), the condition for the contact and reaction between the first liquid phase obtained in step (1) and the calcium carbonate and/or calcium hydroxide and the condition for the contact and reaction between the mixture of the washing liquid of calcium hydrogen citrate and the first liquid phase obtained in step (1) and calcium carbonate and/or calcium hydroxide include: the pH value at the end point of the reaction is 4.5 to 5.5, the reaction temperature is 60 to 80 °C , and the reaction time is 30 to 60 minutes.
8. The method according to claim 1, wherein the method further comprises the following step: carrying out wastewater treatment on the second liquid phase obtained in step (3).
9. The method according to claim 1, wherein the method further comprises the following step: carrying out the processes of ion-exchange, concentration, crystallization and drying on the citric acid obtained in step (2).
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| CN 200910236525 CN102040509B (en) | 2009-10-23 | 2009-10-23 | Method for preparing citric acid |
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| CN105503572A (en) * | 2015-12-29 | 2016-04-20 | 日照金禾博源生化有限公司 | Production method of calcium citrate salt |
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| CN102351687B (en) * | 2011-08-04 | 2013-10-30 | 中粮生物化学（安徽）股份有限公司 | Preparation method of calcium carbonate slurry and preparation method of citric acid |
| CN102390877B (en) * | 2011-08-04 | 2013-04-03 | 中粮生物化学（安徽）股份有限公司 | Treatment method of calcium hydrogen citrate washes and preparation method of citric acid |
| CN102816059B (en) * | 2012-08-28 | 2014-06-04 | 中粮生物化学（安徽）股份有限公司 | Production method and application of calcium hydrogen citrate |
| CN103528975B (en) * | 2013-09-30 | 2016-01-13 | 中粮生物化学（安徽）股份有限公司 | The assay method of readily carbonizable substance and application thereof in a kind of calcium citrate salts |
| CN108360249A (en) * | 2018-02-07 | 2018-08-03 | 枣庄市书源笔业有限公司 | A kind of multi-process writing brush sofening treatment technique |
| CN114307389A (en) * | 2021-12-16 | 2022-04-12 | 潍坊英轩实业有限公司 | Filtering method for improving citric acid extraction yield and feed liquid quality |
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| JPH0648979A (en) * | 1992-07-29 | 1994-02-22 | Idemitsu Petrochem Co Ltd | Method for purifying citric acid |
| CN101117315A (en) * | 2007-07-10 | 2008-02-06 | 安徽丰原生物化学股份有限公司 | Production method of lemon acid |
| CN101643411A (en) * | 2009-06-26 | 2010-02-10 | 安徽丰原发酵技术工程研究有限公司 | Neutralization method of citric acid |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0648979A (en) * | 1992-07-29 | 1994-02-22 | Idemitsu Petrochem Co Ltd | Method for purifying citric acid |
| CN101117315A (en) * | 2007-07-10 | 2008-02-06 | 安徽丰原生物化学股份有限公司 | Production method of lemon acid |
| CN101643411A (en) * | 2009-06-26 | 2010-02-10 | 安徽丰原发酵技术工程研究有限公司 | Neutralization method of citric acid |
Cited By (1)
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| CN105503572A (en) * | 2015-12-29 | 2016-04-20 | 日照金禾博源生化有限公司 | Production method of calcium citrate salt |
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