TWI525074B - Method for purifying an organic acid - Google Patents

Description

Method for purifying organic acid

The present invention relates to a method for purifying an organic acid, and in particular to a method for purifying an organic acid produced by a fermentation process.

There are two main ways to synthesize organic acids, namely chemical methods and biotechnology. The biotechnological synthesis method mainly uses microorganisms to convert a carbon source into an organic acid by fermentation. However, the organic acid produced by fermentation has a low concentration, many impurities and complex impurities, and contains various by-products such as organic acids, so it is quite difficult to establish a simple and low-cost purification procedure.

In addition, the organic acid fermentation broth contains microorganisms, unused carbon sources, suspended solids, various proteins, alcohols, and various other organic acids. Therefore, solid-liquid separation is usually performed through a series of filtration procedures. To remove most of the solid suspended matter, followed by concentration through an evaporator, and then two more crystallization procedures to obtain crude itaconic acid. After the crude itaconic acid is decolorized with activated carbon, the organic acid is refined through a recrystallization procedure.

Since the selectivity of the crystallization procedure is low, a double crystallization procedure is required to obtain a high purity organic acid. However, the concentration process in the dual crystallization process is quite energy intensive, making separation and purification costs a large part of the cost of organic acid production.

Therefore, there is a great need for a purified fermentation process that can effectively save energy. A method of producing an organic acid.

The method for purifying an organic acid of the present invention can solve the low selectivity of a conventional crystallization procedure, and can obtain a high-purity organic acid.

The present invention provides a method for purifying an organic acid, comprising: (a) adding an inorganic flocculant to a fermentation broth containing one organic acid to form a mixture; (b) subjecting the mixture to a centrifugation process to obtain a supernatant a liquid and a precipitate, wherein the organic acid is located in the supernatant; (c) subjecting the supernatant to a membrane extraction procedure to obtain an extract, wherein the membrane extraction procedure comprises: (i) the supernatant The liquid is subjected to an oil phase extraction in an oil phase to form an oil phase extraction product; and (ii) the oil phase extraction product is subjected to a back extraction in a stripping phase to form the extract, wherein during the stripping, the liquid is adjusted a pH of the stripping phase such that at least one carboxyl moiety of the organic acid in the formed extract is in a carboxyl salt state; and (d) subjecting the extract to a crystallization procedure to obtain the organic acid crystallization.

P‧‧‧ pressure gauge

F‧‧‧ Flowmeter

101‧‧‧Polypropylene (PP) hollow fiber module

102‧‧‧ pump

103‧‧‧Shell side (shell side)

104‧‧‧Agitator

105‧‧‧oil phase

107‧‧‧tube side

109‧‧‧Anti-extraction phase

201‧‧‧Adjust pH to pH<7

203‧‧‧Pre-treatment

205‧‧‧ Centrifugation

207‧‧‧Filter

209‧‧‧Ultrafiltration

211‧‧‧ Adjust pH to pH<5.2

213‧‧‧ Film extraction

215‧‧‧ Adjust pH to pH<6.5

217‧‧‧Decolorization and filtration

219‧‧‧ Crystallization

221‧‧‧ evaporation

223‧‧‧Filter

225‧‧‧ Crystallization

225'‧‧‧Evaporation and methanol cleaning

227‧‧‧ Evaporation

OP1-OP9‧‧‧ Output 1 - Output 9

229‧‧‧ Crystallized at 15 ° C

231‧‧‧ Cleaning

233‧‧‧ Evaporation

STEAM‧‧‧Vapor

EVAP-1, EVAP‧‧‧ double effect evaporation can

CRYST-1‧‧‧First Crystall Tank

CFG-1‧‧‧First Centrifuge

EVAP-2‧‧‧Second evaporator

CRYST-2‧‧‧Second Crystallization Tank

CFG-2‧‧‧Second centrifuge

A-CARBON‧‧‧Active carbon tank

FILTER, FILT-1, FILT-2‧‧‧ filter

CRYST-3‧‧‧The third crystallizing tank

CFG-3‧‧ Third Centrifuge

DRYER‧‧‧Dryer

UF‧‧‧Filter

ME‧‧‧ film extraction

MIX-1, MIX-2‧‧‧ mixing device

P-101, P-102, P-103‧‧ pump

Fig. 1 shows a film extraction apparatus used in an embodiment of the present invention.

Fig. 2 is a flow chart showing the purification of itaconic acid according to an embodiment of the present invention.

Fig. 3A shows the flow of the amplification test of the inorganic salt flocculant according to an embodiment of the present invention.

Figure 3B shows a film extraction process in accordance with one embodiment of the present invention.

Figure 3C shows an ultrafiltration process in accordance with an embodiment of the present invention.

Figure 3D shows a decolorization procedure flow in accordance with an embodiment of the present invention.

Figure 3E shows the first crystallization process of an embodiment of the invention.

Figure 3F shows an evaporation, filtration desalination and second crystallization process in accordance with one embodiment of the present invention.

Fig. 3G shows the flow of crystallization refining according to an embodiment of the present invention.

Figure 4 is a graph showing the recovery efficiency of itaconic acid and succinic acid in a film extraction according to an embodiment of the present invention.

Figure 5A shows a simulation flow diagram of a conventional dual crystallization procedure.

Figure 5B shows a simulation flow diagram of the method of the present invention.

The present invention provides a method of purifying an organic acid. Compared with the conventional method for purifying the organic acid produced by the fermentation process, in addition to obtaining a high-purity organic acid, the method for purifying the organic acid of the present invention also has excellent energy-saving effects.

In one embodiment, the method of purifying an organic acid of the present invention may include, but is not limited to, the steps described below.

First, an inorganic flocculant is added to a fermentation broth containing an organic acid produced by a fermentation process to form a mixture. This step can be regarded as a pre-treatment step in which solid suspended impurities in the fermentation broth are precipitated by adding an inorganic flocculant to the fermentation broth to initially separate the organic acid in the fermentation broth from the solid suspended impurities.

Examples of the above organic acid may include, but are not limited to, itaconic acid, succinic acid, maleic acid, citric acid, fumaric acid, Adipic acid is combined with the above. In one embodiment, the above organic acid may be itaconic acid.

Further, the above inorganic flocculating agent may be an inorganic salt, but is not limited thereto. Examples of the above inorganic salts may include, but are not limited to, calcium chloride (CaCl ₂ ), aluminum chloride (AlCl ₃ ), iron chloride (FeCl ₃ ), aluminum sulfate (Al ₂ (SO ₄ ) ₃ -18H ₂ O) in combination with the above. In one embodiment, the inorganic flocculating agent used in the method of the present invention for purifying an organic acid produced by a fermentation process is ferric chloride.

Next, the above mixture was subjected to a centrifugation procedure to obtain a supernatant and a precipitate in which the organic acid was placed in the supernatant. The centrifugation speed of the above centrifugation program is about 4000 to 6000 rpm, but is not limited thereto. In one embodiment, the centrifugation speed is between about 4000 and 6000 rpm. In one embodiment, the centrifugation speed is about 6000 rpm.

Then, the above supernatant is subjected to a membrane extraction procedure to obtain an extract obtained, wherein the obtained extract contains the organic acid obtained by concentration.

The pore size of the filter material used in the above film extraction procedure may be about 0.08-0.45 μm, but is not limited thereto. In one embodiment, the filter material used in the above film extraction procedure has a pore size of about 0.2 μm.

The filter material used in the film extraction process may include, but is not limited to, a hydrophobic filter material or a hollow filter material, and examples of the hydrophobic filter material may include polypropylene (PP), poly. Polytetrafluoroethene (PTFE) and polyvinylidene difluoride (PVDF), etc., but are not limited thereto.

Furthermore, the above film extraction procedure may include the following two steps, but is not limited thereto.

Step 1: First, the above supernatant is subjected to an oil phase extraction in an oil phase to form an oil phase extraction product. The weight ratio of the above supernatant to the above oil phase may be It is about 1-10:1, but is not limited to this.

Further, the oil phase used in the oil phase extraction may include a diluent, a modifier, and an extractant. The weight ratio of the above diluent, modifier and extractant may be about 70-90:5-15:5-15, but is not limited thereto. In one embodiment, the weight ratio of diluent, modifier to extractant can be about 70:15:15. In another embodiment, the weight ratio of diluent, modifier to extractant can be about 80:10:10. Also, in another embodiment, the weight ratio of diluent, modifier to extractant can be about 85:5:10. In another embodiment, the weight ratio of diluent, modifier to extractant can be about 85:7.5:7.5. In yet another embodiment, the weight ratio of diluent, modifier to extractant can be about 85:10:5.

The diluent in the above oil phase may be an organic solvent which is immiscible with water, but is not limited thereto. Examples of the above-mentioned organic solvent which is immiscible with water may include, but are not limited to, kerosene, diesel, biodiesel, sunflower oil, soybean oil, methyl isobutyl ketone, dichloromethane, and 1-octanol and the like.

Further, the modifier in the above oil phase may be an organic solvent containing phosphorus, but is not limited thereto. Examples of the above organic solvent containing phosphorus may include di-2-ethylhexyl phosphoric acid (D2EHPA), tri-n-butylphosphate (TBP) and tri-n-octane. Tri-n-octyl phosphine oxide (TOPO), etc., but is not limited thereto.

The extractant in the above oil phase may be an aliphatic amine, but is not limited thereto. The above aliphatic amines may include, but are not limited to, trioctylmethylammonium chloride (Aliquat 336), lauryl-trialkylmethylamine (Amberlite LA-2), trioctyl hydrazine Amine (tri-n-(octyl-decyl)-amine, TOA) or methyltrioctylamine (MTOA).

After step 1 of the above film extraction procedure is completed, step 2 can be followed. Step 2: The oil phase extraction product obtained in the step 1 is subjected to a back extraction by a stripping phase to form an extract, wherein during the stripping, the pH of the stripping phase is adjusted to form At least one carboxyl moiety of the organic acid in the extract is in a carboxyl salt state. That is, before the film extraction process, the carboxyl moiety of the organic acid to be purified is in a carboxylic acid state, and after the film extraction process, at least one carboxyl moiety of the organic acid to be purified becomes a carboxylate state.

In step 2 of the above membrane extraction procedure, the weight ratio of the oil phase extraction product to the stripping phase may be from about 1 to 4: 4-1. In one embodiment, the weight ratio of the oil phase extraction product to the stripping phase can be about 2:1.

The stripping phase used in the above stripping procedure may include water or a salt solution, but is not limited thereto. Further, examples of the above salt solution may include, but are not limited to, an aqueous NaOH solution, an aqueous NaCl solution, an aqueous Na ₂ CO ₃ solution, an aqueous NH ₃ solution, and the like.

Further, in step 2 of the above film extraction procedure, the pH of the stripping phase can be adjusted to about pH 3.5-11. In one embodiment, the organic acid to be purified is itaconic acid, and the pH of the oil phase extracted product is adjusted to about pH 4-7 in step 2 of the above membrane extraction procedure.

In the method for purifying the organic acid produced by the fermentation process of the present invention, the organic acid can be simultaneously purified and concentrated by the film extraction process, and the amount of treatment in the subsequent evaporation step is reduced, thereby reducing the energy consumption for evaporation. In addition, In the film extraction process, the extractant is not required to be used in a large amount, and the extractant can be reused to continuously recover the product (organic acid).

Finally, in the method for purifying an organic acid of the present invention, after the completion of the aforementioned film extraction procedure, the extract obtained in the film extraction procedure is subjected to a crystallization procedure to obtain crystals of the organic acid to be purified. The above crystallization procedure can be carried out at about 5-15 °C. In one embodiment, the crystallization procedure described above can be carried out at about 10 °C.

The method for purifying the organic acid of the present invention may further include adjusting the fermentation broth to a specific pH before the step of adding the inorganic flocculant to the fermentation broth containing the organic acid, as needed. The value can be about pH 3-7. In one embodiment, the organic acid to be purified is itaconic acid and the above specific pH is about pH 3-6.

Moreover, in another embodiment of the method for purifying an organic acid of the present invention, depending on the need, between the centrifugation procedure and the film extraction procedure, the precipitate obtained by the centrifugation procedure may be further included. The washing solvent is washed and mixed to form a second mixture, and then the second mixture is filtered to form a filtrate and a filter residue, and then the filtrate is added to the supernatant obtained in the above centrifugation program. By recovering the precipitate and recovering the extract, the recovery of the organic acid to be purified can be improved.

In this embodiment, the weight ratio of the above precipitate to the cleaning solvent may be about 1-10:1. Further, examples of the washing solvent may include water, alcohol, acetoacetate, acetone, a combination thereof, and the like, but are not limited thereto.

In addition, in another embodiment of the method for purifying the organic acid produced by the fermentation process of the present invention, as needed, in the above-mentioned centrifugation process and the above-mentioned thin Between the membrane extraction procedures, it may further include performing an ultrafiltration procedure on the supernatant obtained by the above centrifugation procedure.

The nominal molecular weight limit (NMWL) of the filter material used in the above ultrafiltration process may be about 3-30 kDa, but is not limited thereto. In one embodiment, the nominal molecular weight limit of the filter material used in the ultrafiltration process described above can be about 10 kDa.

Furthermore, the filter materials used in the above ultrafiltration process may include, but are not limited to, polystyrene (PS), polysulfone, polypropylene (PP), polyethersulfone (PES). ), polyvinylidene difluoride (PVDF) or a hollow filter material.

Further, in the method for purifying an organic acid of the present invention, between the foregoing film extraction procedure and the crystallization procedure, as needed, and further, the extract obtained in the above membrane extraction procedure is subjected to a microfiltration procedure. The pore size of the filter material used in the microfiltration program may be about 0.2 to 1 μm, but is not limited thereto.

In the method for purifying an organic acid of the present invention, between the foregoing film extraction procedure and the crystallization procedure, as needed, it may further comprise adjusting the extract obtained by the above membrane extraction procedure to a specific pH value, and A particular pH can be about pH 2.5-4. In one embodiment, the organic acid to be purified is itaconic acid and the above specific pH is about pH 2.5-3.

In still another embodiment of the method of the present invention for purifying an organic acid produced by a fermentation process, between the foregoing film extraction process and a crystallization process, as needed, and further comprising, the film extraction process Obtained extract The liquid is subjected to a decolorization procedure. In the decolorization process, soluble impurities can be removed.

The above decolorization procedure can be carried out by adding activated carbon to the above extract and then heating to about 60-90 ° C, but is not limited thereto. In one embodiment, the heating temperature of the decolorizing process can be about 70-80 °C.

In an embodiment of the method of the invention comprising a decolorizing procedure, the crystallization procedure can be carried out by cooling the decolored extract in two stages to about 5-15 °C.

Further, in the method for purifying the organic acid of the present invention, if necessary, after the crystallization step, the extract liquid remaining after the completion of the crystallization procedure may be further subjected to an evaporation procedure to obtain a concentrated extract. Then, the concentrated extract is subjected to a filtration process in a state that has not been cooled (i.e., at a high temperature) to obtain a desalted solution, and then the desalted solution is subjected to a second crystallization procedure to obtain crystals of the organic acid. The above evaporation procedure can increase the concentration of the organic acid, thereby increasing the recovery efficiency of subsequent crystallization. In addition, the solubility of the salt at a high temperature is much lower than that of the organic acid, and the effect of performing the desalination can be achieved by performing the filtration process under the above-described state without cooling.

The above state that has not been cooled is a high temperature state, which may be about 60-90 °C. In one embodiment, the above-described state in which the temperature has not been lowered may be about 70-80 °C.

The second crystallization procedure described above can be carried out by cooling the desalted solution to about 5-15 ° C in two stages, but is not limited thereto. In an embodiment. This can be carried out by cooling the desalted solution in two stages to about 10 °C.

In addition, as the case requires, after the second crystallization step, the desalting remaining after the completion of the second crystallization step may be further included. The solution is subjected to an evaporation procedure to obtain a concentrated desalting solution, and then the concentrated desalted solution is subjected to a third crystallization procedure to obtain a solid containing the organic acid, and then the solid is washed with a washing solvent to wash off the organic acid. And finally, the organic acid is subjected to an evaporation procedure to remove the cleaning solvent and obtain the organic acid crystal.

The above third crystallization procedure can be carried out at about 5-15 ° C, but is not limited thereto. In one embodiment, the third crystallization procedure can be performed at about 15 °C.

Further, the weight ratio of the above solid to the cleaning solvent for washing the solid may be about 1:1-4, but is not limited thereto. In one embodiment, the weight ratio of the solid to the cleaning solvent used to clean the solid may be about 1:3. Further, examples of the washing solvent for washing the solid may include, but are not limited to, water, alcohol, acetoacetin, acetone, a combination thereof, and the like.

By purifying the organic acid produced by the fermentation process by the method of the present invention, energy consumption of at least 60% can be saved compared to conventional methods. Further, by purifying the organic acid produced by the fermentation process by the method of the present invention, a recovery efficiency of at least 85% can be achieved.

Example

Example 1

Conditional test

A. Precipitation test of inorganic salt flocculant

In this test, the itaconic acid fermentation broth was tested for precipitation with various inorganic flocculants.

Because the composition of itaconic acid fermentation broth is quite complicated, not only a variety of small molecule salts and organic acids, but also many solid impurities that cause membrane clogging, so if the initial separation is only by microfiltration, the microfiltration membrane is likely to be serious. Scaling, which causes a severe attenuation of the filtration rate and will result in a decrease in the service life of the film. Therefore, when purifying the itaconic acid from the fermentation broth, pretreatment is required to reduce solid impurities. In this test, four common inorganic salts CaCl ₂ , Al ₂ (SO ₄ ) ₃ .18H ₂ O, AlCl ₃ and FeCl _{3 were used} as flocculants.

After adjusting the fermentation broth to an appropriate pH, an appropriate concentration of 1 ml of the flocculant solution was taken in 20 ml of the fermentation broth, and stirred at room temperature for 1 hour to form a mixture (in a glass container). Next, 8 or 10 g of the above mixture was allowed to stand in a centrifuge tube for 1 hour, and then centrifuged at 6000 rpm for 5 minutes to remove complicated solid impurities by sedimentation centrifugation. Then, the upper layer clear liquid was taken for particle size and concentration analysis. The results of the fermentation broth of pH 6 and the fermentation broth of pH 3 are shown in Tables 1 and 2, respectively.

In this test, the effect of the flocculant on the pretreatment of different pH fermentation broths was judged by the weight of the lower layer liquid after sedimentation centrifugation, the particle size analysis of the supernatant liquid, and the loss of itaconic acid.

According to Table 1, when the pH of the fermentation broth is 6, the pretreatment is carried out under the conditions of A3, A7 and A8. The flocculant can effectively function and increase the particle size of the molecule, so that many impurities can be sedimented by centrifugation. However, the IA losses caused by them were 24.4%, 40.0% and 27.7% respectively.

According to Table 2, in the case where the pH of the fermentation broth is 3, pretreatment with B5 and B9 conditions can obtain better separation efficiency and lower itaconic acid loss.

B. Film extraction

1. Membrane extraction device and operating conditions

The Liqui-cel polypropylene (PP) hollow fiber module was used as a dispersion-backed phase-supported liquid membrane to recover itaconic acid. Figure 1 shows the film extraction apparatus used in the experiments of the present invention.

Referring to Fig. 1, the left side of a polypropylene (PP) hollow fiber module 101 is a shell side 103, and a polypropylene hollow fiber module. The right side of 101 is the tube side 107. During film extraction, a mixture 105 of an organic acid-containing oil phase and a stripping phase is introduced into the shell side 103 from the top down via a line, and the feed supernatant 109 is introduced into the column side 107 from bottom to top via a line. . In contrast, during cleaning of the polypropylene hollow fiber module 101, the cleaning liquid is introduced into the shell side 103 from the bottom up through the pipeline to clean the shell side 103, and the cleaning liquid is introduced into the tube side 107 from above through the pipeline to clean the tube. Side 107.

According to Figure 1, the pipeline is connected. After confirming that the pipeline process is correct, the magnetic stirrer of the feed and the peristaltic pump connected to the feed supernatant are turned on, and the rotational speed of the peristaltic pump is adjusted to deliver the feed supernatant to the hollow at a flow rate of 0.5 to 1 L/min. The tube side 104 of the fiber module 101. The hollow fiber module 101 is upright in operation, and the flow direction of the feed supernatant is downward and upward. Since the hollow fiber tube is made of hydrophobic polypropylene, after the feed solution fills the tube side and flows out, adjust the flow meter valve and apply a pressure of about 4 psi on the tube side to prevent the oil phase and the back extraction phase from penetrating into the feed. In solution. Mix appropriate amount of extractant (oil phase) and stripping agent (back extraction phase) into the same container, adjust the stirring blade of the stirrer to expand between the two liquid levels, turn on the stirrer, set the speed at 300 rpm, and make two The phase is uniformly dispersed.

The peristaltic pump power supply connected to the oil phase is turned on, the rotation speed on the peristaltic pump is adjusted, and the dispersion of the oil phase and the back extraction phase is delivered to the shell side 103 of the module 101 at a flow rate of 0.5 L/min, and the flow direction is upward and downward. In contrast to the feeder-current flow. When the mixed solution of the feed supernatant and the oil phase/back extraction phase is in contact with the interface of the film, the time from the beginning of the oil phase to the module starts to be counted at a certain time point (every 30 minutes), and the quantitative amount is taken. The supernatant and oil are taken for subsequent measurement steps.

After the end of the experiment, the oil phase and the back extraction phase liquid were separately collected, and the membrane group was washed with 2 wt% NaOH aqueous solution, isopropyl alcohol and pure water, respectively, and high-pressure air was input from the pipeline feed end of the tube layer and the shell layer, so that It was dried for 4 hours.

2. Film extraction test

(a) Oil phase extraction test

The oil phase of the film extraction comprises a diluent, a modifier and an extractant. The choice of modifiers is that they help the compound formed by the extractant and the organic acid to be dissolved in the diluent, and secondly, the price and water solubility are considered. However, the choice of the extractant is focused on the effective purification of the desired purification. The organic acid can be easily re-extracted into the aqueous phase, followed by its biological toxicity and price.

In this test, di-2-ethylhexyl phosphoric acid (D2EHPA) or tri-n-butylphosphate (TBP) was used as a modifier, and methyl three was used. Trioctylmethylammonium chloride (Aliquat 336) or tri-n-(octyl-decyl-amine, TOA) is used as an extractant, and its use and selectivity in multi-component extraction are discussed. The characteristics of the modifier and the extractant used are shown in Table 3.

The structure of the modifier, di-2-ethylhexyl phosphoric acid (D2EHPA) and tri-n-butylphosphate (TBP) are as follows: di(2-ethyl) Hexyl)phosphoric acid (D2EHPA)

Tributyl phosphate (TBP)

In addition, the structure of the extractant, trioctylmethylammonium chloride (Aliquat 336) or tri-n-(octyl-decyl-amine, TOA) is as follows: methyl trisin Ammonium chloride (Aliquat336)

Trioctylamine (TOA)

In this test, extraction was carried out in a shake flask experiment. The feed was 20 g of a mixed organic acid aqueous solution, the feed composition was 20 mg/ml of itaconic acid, 3.7 mg/ml of citric acid (CA), 2.9 mg/ml of malic acid (MA), 0.87 mg/ml succinic acid (SA) and 4.7 mg/ml (glycerol glycerol, Gly). The feed acid purity of the feed was 61.7%. The oil phase is a mixed solution of 20 g of a diluent, a modifier and an extractant.

The flask was shaken at 30 ° C and 100 rpm for 2 hours, and the stripping solution was 20 g of a 0.34 M NaCl aqueous solution. The pH of the feed supernatant must be adjusted before the experiment, because the extractant selected here requires itaconic acid to form a compound with the extractant under non-dissociated conditions. The pka of itaconic acid is 3.65 and 5.13, so here the extraction is carried out with a fixed pH adjustment at pH 3. The experimental results are shown in Table 4.

According to Table 4, it can be seen from Experiments A, B and C that if TBP is used as a modifier, the compound formed by itaconic acid and the extractant is not dissolved in the oil phase and the aqueous phase, so that the third phase is produced, which may be disadvantageous. For the film extraction system, it is therefore preferred to use D2EHPA as a modifier.

From experiments A, D, E and F, it was found that the itaconic acid recovery rate did not increase with the increase of the concentration of the modifier and the extractant, but instead the combination of the diluent and the modifier plus the extractant was 85 to 15. The best, wherein the ratio of modifier to extractant has no significant effect on the recovery rate, only the viscosity of the solution is different, and the purity of itaconic acid recovered by experiment F is the highest, so the difference of experiment F is discussed. The effects of extractants and thinners.

From the results of experiments F, G, H and I, it is known that the different combinations have no significant difference in the purity of the finally recovered itaconic acid, but the use of biodiesel can obtain a higher recovery rate, but the biodiesel is extracted. The viscosity is high, so pay attention to the solution change when using, to avoid the problem of scaling caused by increased viscosity.

(b) Back extraction test

In the case of back extraction, in this test, extraction was carried out in a shake flask experiment. The feed was 20 g of a mixed organic acid aqueous solution, the feed composition was 23.4 mg/ml of itaconic acid, 2.2 mg/ml of citric acid, 2.65 mg/ml of malic acid, 0.85 mg/ml of succinic acid, 4.2 mg/ Mg of glycerol and 13.9 mg/ml of MeOH. The IA purity of the feed was 49.5%. 20g of a mixture solution of 85wt% kerosene, 10wt% D2EHPA and 5wt% Aliquat336 contained in the oil phase, shaken at 30 ° C and 100 rpm for 2 hours, and the stripping agent is 20 g of NaCl, NaOH or Na ₂ Aqueous CO ₃ solution.

According to Table 5, the purity of itaconic acid after recovery is above 70% regardless of the salt used or the concentration of different salts. Among them, Na ₂ CO ₃ or high concentration of NaCl has the best effect. The use of NaOH or Na ₂ CO ₃ as the stripping agent has the highest recovery efficiency, but there is a third phase formation and an increase in solution viscosity during stripping. Therefore, in order to avoid the occurrence of fouling, the life of the film is reduced, and whether or not fouling occurs becomes the most important choice.

Example 2

Purification of itaconic acid from itaconic acid fermentation broth

A. Process overview

The itaconic acid purification flow chart is shown in Figure 2. See Figure 2. One liter of the fermentation broth having an original pH of about 6-7 was used, and its pH was adjusted to 3 with 6 M of H ₂ SO ₄ (step 201). Then, a 2M FeCl ₃ solution is added for pretreatment (step 203) and stirred at room temperature for uniformity. After standing for several hours, the supernatant is centrifuged (step 205), and the lower aqueous precipitate is filtered by suction (step) 207) and appropriate amount of water washing, dissolve the itaconic acid aqueous solution to reduce the loss of itaconic acid. The itaconic acid solution is then continuously removed by ultrafiltration to remove small molecules of solid impurities (step 209). The pH of the filtrate is adjusted to less than 5.2 (step 211) and purified and concentrated by membrane extraction (step 213). Thereafter, the purified itaconic acid solution is concentrated (not necessary), and after adjusting the pH of the solution (step 215), decolorization of activated carbon is carried out (step 217). The crystal is cooled to 10 degrees to carry out crystallization (step 219), and an appropriate amount of high-purity itaconic acid crystal is collected, and the remaining liquid is concentrated to a certain extent by evaporation (step 221), and then filtered and desalted at a high temperature (step 223). After cooling, crystallization is carried out (step 225) to obtain itaconic acid crystals.

B. Tests and results of each step

1.Fe series of flocculant pretreatment amplification test

The flow of the inorganic salt flocculant amplification test is shown in Figure 3A. See Figure 3A. After adjusting the pH of the feed fermentation liquid to 3 by using 6 M H ₂ SO ₄ (step 201), an appropriate amount of 2 M FeCl ₃ solution (step 203) was added and stirred at room temperature, and then allowed to stand for several hours. Pre-treatment. Thereafter, the pre-treated fermentation broth is centrifuged to obtain a supernatant (step 205), and the lower layer is washed with an appropriate amount of water and then filtered (step 207). The weight percentage of the cleaning liquid to the fermentation broth is about 0:1 to 1:1. The processing results are shown in Table 6.

It should be noted that the samples with the same numerical part of the sample name shown in the tables below are the samples that are consistent with the previous step.

Table 6, Fe series flocculant pretreatment

According to Table 6, the recovery of itaconic acid was increased to 90-100% by this treatment step.

2. Ultrafiltration

Figure 3B shows the flow of the ultrafiltration process. The supernatant after the flocculation treatment is mixed with the filtrate washed by the lower layer of water into the ultrafiltration process. Ultrafiltration was carried out with a 10 kDa polysulfon hollow fiber membrane (step 209), the pressure of the ultrafiltration was controlled at 5-10 psi, and the sweep speed was controlled at 5 L/min. The treatment results are shown in Table 7.

According to Table 7, in the ultrafiltration step, the itaconic acid recovery rate was about 96.7-100%, and the recovery filtration rate was about 2.33-15 ml/m ² -min.

3. Thin film extraction

Figure 3C shows the flow of the thin film extraction. The PP hollow fiber module of Liqui-cel is used as a liquid film with a dispersed back extraction phase to carry out film extraction (step 213) to recover itaconic acid after ultrafiltration.

In the case where the extractant composition was kerosene/D2EHPA/Aliquat 336 and was repeatedly used, itaconic acid was recovered after ultrafiltration, and the results are shown in Table 8.

Table 8, film extraction

According to Table 8, in the film extraction procedure, it can be concentrated 2-4 times of itaconic acid with 0.5-5.5M NaOH within 2-4 hours of operation time, the recovery rate is 63.8-112.5%, and itaconic acid is recovered. The filtration rate was 1.6-9.3 gIA/m ² hr.

3. Decolorization

Figure 3D shows the flow of the decolorization procedure. See Figure 3C. The concentrated itaconic acid solution will be purified by membrane extraction, and 1 wt% of activated carbon (step 217A) is added between pH 3-5.66 to perform decolorization at 70-80 ° C (step 217B). The results are shown in Table 9.

According to Table 9, it can be seen that after the decolorization treatment, the recovery of itaconic acid is between 70.7 and 100%, wherein a good recovery is obtained by decolorization at pH 3 or below.

4. First crystallization

Figure 3E shows the flow of the first crystallization. See Figure 3E. will Solution adjustment In the case of a pH of 3, the two-stage cooling is carried out to 10 degrees for crystallization (step 219). The results of the itaconic acid recovery are shown in Table 10.

According to Table 10, the crystal purity of the first crystallization was 94.5 to 99.4%, and the crystal recovery was 14.6 to 50.3%.

Subsequent itaconic acid solution (D _out ) can be further evaporated to remove water for a second crystallization.

5. Evaporation, filtration, salt removal, second crystallization

Figure 3F shows the flow of evaporation, filtration, desalination and second crystallization. See Figure 3F. The itaconic acid solution is first concentrated by evaporation (step 221) to a certain extent. Next, since the solution also contains a high concentration of NaCl, the solubility of the salt at a high temperature is much lower than that of the organic acid, and the salt is removed by filtration (step 223). Then, the temperature is lowered to 10 ° C in two stages to carry out crystallization (step Step 225). The results of the second crystallization were as shown in Table 11.

According to Table 11, the crystal purity after evaporation, filtration and desalting and the second crystallization was 71.7-99.5%, and the crystal recovery of the second crystal was 16.8-47.5%.

The subsequent itaconic acid solution (C _out2 ) can be returned to between step 219 and step 221 in Fig. 2, or the crystallization can be continued in the following manner.

6. Crystal refining

Fig. 3G shows the flow of crystallization refining. See Figure 3G. The itaconic acid solution from C _out2 in the 3F diagram is further evaporated to remove most of the water (step 227), and crystallized at a low temperature (step 229) to produce solid crystals. The solid crystals were then washed (step 231) with methanol in a weight ratio of 1:3-4. After washing out the solution containing itaconic acid, the methanol is removed by evaporation (step 233). The itaconic acid recovery results of the crystallization refining process are shown in Table 12.

According to Table 12, in the process of crystallization refining, the recovery rate of itaconic acid can reach 97.1-100%, the purity before undone is 55-87% (containing methanol), and the purity after drying in vacuum oven can reach 98%. the above.

7. Overall recovery rate

See Figure 2. The yields of the various processes indicated in Figure 2, the itaconic acid recovery of the yields (OP) 1-9, and the overall recovery of the purification process of the present invention are shown in Table 13 below, respectively.

Table 13 shows that the process of pre-treatment, ultrafiltration and membrane extraction lost 0 to 9.6% of itaconic acid, while in output 7, output 8 and output 9, a total of 91.1 to 92.3% of Yikang was recovered. Acid The itaconic acid has a recovery of 85% or more by the purification method of the present invention.

Example 3

Recovery of succinic acid in thin film systems

The mixture of kerosene/D2EHPA/Aliquat336 was used as an extractant, and a mixed solution of 2M NaOH and 5M NaCl was used as a back extraction phase to carry out film extraction of a feed containing 58.7 g/L of succinic acid fermentation broth. The results are shown in Table 14.

The results showed that film extraction recovered 90.4% of succinic acid. Moreover, the recovery benefits of itaconic acid and succinic acid in the film extraction are shown in Fig. 4. As can be seen from Fig. 4, in the film extraction process, if appropriate conditions are employed, more than 90% of the target organic acid can be recovered in a four hour operation time.

Further, the succinic acid fermentation broth was purified in the same purification procedure as shown in Example 2. The succinic acid recovery of the yields (OP) 1-9, as well as the overall recovery of the purification process of the present invention, are shown in Table 15 below, respectively, according to the outputs of the various processes indicated in Figure 2.

The results showed that the overall process recovery of succinic acid in the purification process was about 70.3%, which was lower than itaconic acid. No decolorization was required during the purification process, and only one concentration and crystallization procedure was required.

Example 4

Comparison of energy consumption assessment and recovery rate between the present invention and prior art

1. Energy consumption analysis of traditional double crystal mode

The commercial itaconic acid process is the purification of itaconic acid by continuous evaporation and two-stage crystallization. A flow chart of the separation and purification procedure for commercialized double crystals was simulated in this experiment. The flow chart of the separation and purification procedure for commercial double crystals is shown in Fig. 5A.

The filtered fermentation broth was passed from the storage tank to the first stage evaporation system (EVAP-1) to concentrate the fermentation broth from 10 wt% itaconic acid to 37 wt%. The first stage of the evaporation system uses a double-effect evaporation system (EVAP-1) (EVAP-1 is a double-effect evaporation tank, so two evaporations are calculated in the calculation. Energy consumption, energy consumption is E-201 & E-202). The concentrated fermentation broth is then passed to the first crystallization tank (CRYST-1), and the crystallization temperature is operated at 15 ° C, and about 90% of itaconic acid can be crystallized therefrom. The remaining liquid is then passed to the first centrifuge (CFG-1) to separate the solid and liquid. The centrifuged liquid enters the second evaporator (EVAP-2) (energy consumption E-203) and continues to be concentrated and dehydrated, then enters the second crystallization tank (CRYST-2), the crystallization temperature is operated at 15 ° C, and then enters the second centrifuge (CFG). -2) Separating solid and liquid, about 5% of itaconic acid can be recovered, and the remaining liquid after centrifugation is used as waste. The crystal itaconic acid separated by centrifuges CFG-1 and CFG-2 needs to enter the activated carbon tank (A-CARBON), containing 1% by weight of activated carbon of itaconic acid, and dissolve itaconic acid at 80 °C hot water. The itaconic acid was decolorized, and then the activated carbon and solid impurities were filtered off with a filter (FILTER). The decolored reaction filtrate enters the third crystallization tank (CRYST-3), the crystallization temperature is operated at 15 ° C, and then enters the third centrifuge (CFG-3) to separate the solid and liquid, and the crystal itaconic acid is separated therefrom and then enters. The rotary dryer (DRYER) continues to dehydrate and dry, and finally the itaconic acid purity reaches 99.5 wt%. The centrifuged centrifuge CFG-3 still contains a small amount of itaconic acid, which can be recycled into the first stage evaporation system (EVAP-1) and continue to recover itaconic acid to increase recovery.

A simulated flow chart of a conventional double crystallization procedure is shown in Figure 5A to analyze the simulated energy consumption of E. coli fermentation (Titer = 8%) + conventional double crystal process.

The design basis of the above simulation is as follows:

Fermentation liquid itaconic acid concentration = 8 wt%, itaconic acid recovery rate = 95%.

Itaconic acid production = 20,000 tons / year.

Operating hours = 8,000 hr / year.

However, the results are shown in Table 16.

2. Energy consumption analysis of the method of the invention

Figure 5B shows a simulation flow diagram of the method of the present invention. As can be seen from Figure 5B, the method of the present invention requires, inorganic salt pretreatment, centrifugation (CFG-1), filtration (FILT-1), filtration (UF), membrane extraction (ME), first crystallization and centrifugation. (CRYST-1, CFG-1), Decolorization (A-CARBON), Filtration (FILT-2), Reducing Double Effect Evaporator (EVAP) (EVAP is a double effect evaporation tank, so two evaporations are calculated in calculation The energy consumption, energy consumption is E-201 & E-202), the second crystallization and centrifugation (CRYST-2, CFG-2), dryer (DRYER) and pump (Pumps) and other procedures and devices, in Figure 5B MIX-1 and MIX-2 are shown as two devices for mixing two feeds.

A simulated flow diagram of the method of the invention is shown in accordance with Figure 5B to analyze E. coli fermentation (Titer = 8%) + simulated energy consumption of the method of the invention.

The design basis of the above simulation is as follows:

Fermentation liquid itaconic acid concentration = 8 wt%, itaconic acid recovery rate = 95%.

Itaconic acid production = 20,000 tons / year.

Operating hours = 8,000 hr / year.

However, the results are shown in Table 17.

3. Comparison of traditional double crystals with the method of the invention for recovering itaconic acid

Based on the results shown in Tables 16 and 17, the characteristics of the conventional double crystallization procedure and the method of the present invention for recovering itaconic acid were integrated in Table 18.

201‧‧‧Adjust pH to pH<7

203‧‧‧Pre-treatment

205‧‧‧ Centrifugation

207‧‧‧Filter

209‧‧‧Ultrafiltration

211‧‧‧ Adjust pH to pH<5.2

213‧‧‧ Film extraction

215‧‧‧ Adjust pH to pH<6.5

217‧‧‧Decolorization and filtration

219‧‧‧ Crystallization

221‧‧‧ evaporation

223‧‧‧Filter

225‧‧‧ Crystallization

225'‧‧‧Evaporation and methanol cleaning

OP1-OP9‧‧‧ Output 1 - Output 9

Claims (33)

A method for purifying an organic acid, comprising: (a) adding an inorganic flocculant to a fermentation broth containing one organic acid to form a mixture; (b) subjecting the mixture to a centrifugation procedure to obtain a supernatant and a a precipitate in which the organic acid is located in the supernatant; (c) subjecting the supernatant to a membrane extraction procedure to obtain an extract, wherein the extract contains the concentrated organic acid, wherein the membrane extraction procedure The method comprises: (i) performing an oil phase extraction on an oil phase to form an oil phase extraction product; and (ii) performing a back extraction of the oil phase extraction product in a stripping phase to form the extract And wherein during the stripping, the pH of the stripping phase is adjusted so that at least one carboxyl moiety of the organic acid in the formed extract becomes a carboxyl salt state; and (d) the extract is subjected to A crystallization procedure is performed to obtain crystals of the organic acid. The method for purifying an organic acid according to claim 1, wherein the organic acid comprises itaconic acid, succinic acid, maleic acid, citric acid, Fumaric acid, adipic acid or a combination thereof. The method of purifying an organic acid according to claim 1, wherein the flocculating agent comprises an inorganic salt. The method for purifying an organic acid according to claim 3, wherein the inorganic salt comprises calcium chloride (CaCl ₂ ), aluminum chloride (AlCl ₃ ), iron chloride (FeCl ₃ ), aluminum sulfate (Al). ₂ (SO ₄ ) ₃ -18H ₂ O) or a combination of the above. The method for purifying an organic acid according to claim 1, wherein the filter material used in the film extraction process comprises a hydrophobic filter material or a hollow filter material. The method for purifying an organic acid according to claim 1, wherein the hydrophobic filter material may comprise polypropylene (PP), polytetrafluoroethene (PTFE) or polyvinylidene difluoride (polyvinylidene difluoride). , PVDF). The method of purifying an organic acid according to claim 1, wherein the weight ratio of the supernatant to the oil phase is about 1-10:1. The method of purifying an organic acid according to claim 1, wherein the oil phase comprises a diluent, a modifier and an extractant. The method of purifying an organic acid according to claim 8, wherein the diluent, the weight ratio of the modifier to the extracting agent is about 70-90:5-15:5-15. The method of purifying an organic acid according to claim 8, wherein the diluent is an organic solvent which is immiscible with water. The method for purifying an organic acid according to claim 8, wherein the modifying agent is an organic solvent containing phosphorus. The method of purifying an organic acid according to claim 8, wherein the extracting agent is an aliphatic amine. The method of purifying an organic acid according to claim 1, wherein the weight ratio of the oil phase extraction product to the stripping phase is about 1-4:4-1. A method of purifying an organic acid as described in claim 1, wherein the pH of the oil phase extraction product is adjusted to about pH 3.5-11 in step (ii). A method of purifying an organic acid as described in claim 1, wherein the organic acid is itaconic acid, and the pH of the oil phase extraction product is adjusted to about pH 4-7 in step (ii). A method of purifying an organic acid as described in claim 1, wherein the stripping phase comprises water or a salt solution. A method of purifying an organic acid as described in claim 1, wherein the crystallization procedure is carried out at about 5-15 °C. The method for purifying an organic acid as described in claim 1, further comprising, prior to the step (a), adjusting the fermentation broth to a specific pH, wherein the specific pH is about pH 3-7. The method for purifying an organic acid according to claim 1, wherein between the step (b) and the step (c), the method further comprises: washing and mixing the precipitate with a cleaning solvent to form a second a mixture; the second mixture is filtered to form a filtrate and a filter residue; and the filtrate is added to the supernatant. The method of purifying an organic acid according to claim 19, wherein the weight ratio of the precipitate to the washing solvent is about 1-10:1. The method for purifying an organic acid according to claim 1, wherein between the step (b) and the step (c), the supernatant is further subjected to an ultrafiltration process. The method for purifying an organic acid according to claim 21, wherein the filter material used in the ultrafiltration process comprises polystyrene (PS), polysulfone, polypropylene, and polypropylene. PP), polyethersulfone (PES), polyvinylidene difluoride (PVDF) or a hollow filter material. The method for purifying an organic acid according to claim 1, wherein between the steps (c) and (d), the extract is further subjected to a microfiltration process. The method for purifying an organic acid according to claim 1, wherein between the steps (c) and (d), the extract is further adjusted to a specific pH, wherein the specific pH is about pH 2.5. -4. The method of purifying an organic acid according to claim 24, wherein the organic acid is itaconic acid, and the specific pH is about pH 2.5-3. The method for purifying an organic acid according to claim 1, wherein between the steps (c) and (d), the extract is further subjected to a decolorization procedure. A method of purifying an organic acid as described in claim 26, wherein the decolorization procedure is carried out by adding activated carbon to the extract and then heating to about 60-90 °C. A method of purifying an organic acid as described in claim 27, wherein the crystallization procedure is carried out by cooling the extract in two stages to about 5-15 °C. The method for purifying the organic acid according to the first aspect of the patent application, after the step (d), further comprises: (e) subjecting the extract remaining after the completion of the crystallization procedure to an evaporation procedure to obtain a concentration An extract; (f) performing a filtration process on the concentrated extract without a cooling to obtain a desalted solution; and (g) subjecting the desalted solution to a second crystallization procedure to obtain the organic acid Crystallization. A method of purifying an organic acid as described in claim 29, wherein the second crystallization procedure is carried out by cooling the desalted solution to a temperature of about 5-15 °C. The method for purifying an organic acid according to claim 29, after the step (g), further comprising: (h) performing an evaporation of the desalted solution remaining after the completion of the second crystallization procedure a procedure to obtain a concentrated desalting solution; (i) subjecting the concentrated desalting solution to a third crystallization procedure to obtain a solid containing the organic acid; (j) washing the solid with a cleaning solvent to wash out the organic (k) subjecting the organic acid to an evaporation procedure to remove the washing solvent and obtaining the organic acid crystal. A method of purifying an organic acid as described in claim 31, wherein the third crystallization procedure is carried out at about 5-15 °C. The method of purifying an organic acid according to claim 31, wherein the weight ratio of the solid to the washing solvent is about 1:1-4.