Method for producing lactic acid solution, method for producing lactic acid derivative, lactic acid solution production system, and carbon-based adsorbent composition

Abstract

To provide a method for producing a lactic acid solution, enabling suppression of by-product formation and allowing production of a lactic acid solution under a low environmental load.SOLUTION: A method for producing a lactic acid solution, the method comprising: bringing lactic acid produced by lactic fermentation into contact with a carbon-based adsorbent and / or a carbon-based adsorbent composition, thereby allowing the lactic acid to be adsorbed onto the carbon-based adsorbent and / or the carbon-based adsorbent composition; and bringing a post-adsorption adsorbent having adsorbed the lactic acid into contact with a solvent containing an alcohol, thus extracting the lactic acid into the solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a lactic acid solution, a method for producing a lactic acid derivative, a system for producing a lactic acid solution, and a carbon-based adsorbent composition. [Background technology]

[0002] Lactic acid is used not only as a food additive in the production of foods (e.g., sake, soft drinks, pickles, soy sauce, bread, beer, etc.) but also in the production of industrial products (e.g., leather, textiles, plastics, pharmaceuticals, pesticides, etc.). Lactic acid derivatives, such as lactic acid esters (e.g., ethyl lactate or butyl lactate), are finding widespread applications as highly safe solvents and cleaning agents. In particular, when lactic acid esters are used as raw materials for pharmaceuticals or pesticides, lactic acid esters produced from highly pure lactic acid with high optical activity are required. Highly pure lactic acid with high optical activity is produced by fermentation. Another lactic acid derivative is acrylic acid, which is obtained by the dehydration reaction of lactic acid. Acrylic acid is used as a raw material for superabsorbent resins, dispersants, flocculants, thickeners, adhesives, etc.

[0003] Lactic acid can be produced by fermentation in an aqueous solvent. As fermentation progresses, the pH of the solution decreases due to an increase in lactic acid, which can lead to fermentation disorders (e.g., a decrease in microbial function). For this reason, fermentation is carried out while neutralizing the solution by adding a neutralizing agent (e.g., calcium carbonate or ammonia) (hereinafter also referred to as "neutralized fermentation"). However, in neutralized fermentation, lactic acid is obtained in the form of a lactate salt, requiring a desalination step and a lactic acid separation / extraction step (Non-Patent Documents 1-2, Patent Documents 1-3).

[0004] On the other hand, fungi (e.g., yeast, mold, etc.) have high acid resistance. Therefore, by using them for fermentation, lactic acid can be produced without neutralization. A known method involves pre-purifying an aqueous lactic acid solution obtained by fermentation with recombinant yeast, contacting the resulting aqueous lactic acid solution with a type II strongly basic ion exchange resin to adsorb lactic acid onto the resin, and then extracting the lactic acid into an aqueous mineral acid solution (see Patent Document 4). Another known method involves contacting an aqueous lactic acid solution obtained by fermentation with recombinant yeast with a carbonized material to adsorb lactic acid onto the carbonized material, followed by extraction into acetone (see Patent Document 5). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Yoshiharu Kimura, "Creating a petroleum-independent polymer, polylactic acid," Polymer, Vol. 64, No. 5 (2015), pp. 278-282. [Non-patent document 2] Fukushima, K., et al., “Production of D-Lactic Acid by Bacterial Fermentation of Rice Starch”, Macromolecular Bioscience, Vol.4, No.11(2004), pp.1021-1027. [Non-patent document 3] Michiomi Kimura, “Common knowledge about lactic acid,” Journal of the Japan Sewage Association, Vol. 74, No. 3 (1979), pp. 145-147. [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-43860 [Patent Document 2] Japanese Patent Application Publication No. 6-311886 [Patent Document 3] Japanese Patent Application Publication No. 7-155191 [Patent Document 4] Japanese Patent Application Laid-Open No. 2014-39505 [Patent Document 5] Japanese Patent Application Laid-Open No. 2010-000025 Summary of the Invention [Problem to be solved by the invention]

[0007] In neutralization fermentation, lactic acid is obtained in the form of lactate. Therefore, it is necessary to liberate lactic acid from the lactate by, for example, adding an acid in an amount equal to the molar amount of lactate to the lactate. In the most common method of neutralization using calcium carbonate, sulfuric acid is added to calcium lactate to liberate lactic acid (Non-Patent Documents 1-2, Patent Document 1). A problem is that calcium sulfate (gypsum) is generated as a by-product, accounting for approximately 75% by mass of the mass of lactic acid obtained.

[0008] Methods that do not produce calcium sulfate include those disclosed in Patent Document 2 and Patent Document 3. Patent Document 2 discloses a method in which lactic acid is obtained by neutralizing with ammonia, concentrating the mixture, esterifying it with an alcohol having 4 or 5 carbon atoms to remove ammonia, distilling and concentrating the mixture, and then hydrolyzing the resulting lactic acid ester in the presence of a mineral acid. The method disclosed in Patent Document 2 involves many steps involving heating at 100°C or higher. This poses a problem of high energy consumption. Patent Document 3 discloses a method in which lactic acid is purified by electrodialysis or ion exchange resins after neutralizing with ammonia. In the method disclosed in Patent Document 3, electrodialysis requires high purification equipment and operating costs, and ion exchange resins require regeneration treatment after use, raising concerns about processing costs and environmental pollution caused by regenerating chemicals.

[0009] In non-neutralized fermentation using yeast, a type of fungus with high acid tolerance, Patent Document 4 describes adsorbing the resulting lactic acid onto an ion exchange resin and then extracting it with an aqueous mineral acid solution. As mentioned above, ion exchange resins require regeneration after use. In addition, the extract contains large amounts of mineral acid salts and water-soluble organic chemicals used to increase extraction efficiency, necessitating a process for separating the lactic acid. Patent Document 5 describes adsorbing the resulting lactic acid onto a carbonized material and then extracting it with acetone. When reusing the carbonized material after extraction, it is heated at 200°C for one hour. This poses a problem: the remaining lactic acid evaporates and is lost. Furthermore, when using acetone-extracted lactic acid for esterification or other purposes, it is necessary to completely remove the acetone to avoid inhibiting the synthesis reaction of lactic acid derivatives. Lactic acid has a low vapor pressure and is prone to thermal denaturation and self-condensation. This makes distillation difficult (Non-Patent Document 3). Therefore, acetone is removed by concentration. When the lactic acid concentration exceeds 90%, polymerization due to self-condensation progresses (Non-Patent Document 3), making it difficult to return the lactic acid to lactic acid monomer. Therefore, to completely remove acetone, the process must be repeated: concentrate the solution to 90%, add another solvent, and then concentrate it again to 90%, which requires a lot of effort and energy.

[0010] A common problem in the prior art and the above-mentioned prior art documents is the energy required for concentration. Specifically, when synthesizing a lactic acid derivative (e.g., a lactic acid ester or acrylic acid), the lactic acid solution must be concentrated to a high concentration (e.g., a lactic acid concentration of 90% by mass) for solvent substitution. When synthesizing a lactic acid derivative, the solvent preferably contains an alcohol. In particular, when synthesizing a lactic acid ester, the solvent must contain an alcohol. Lactic acid fermentation is carried out in an aqueous solvent. Additionally, in the prior art documents, the solvent used after separating and extracting lactic acid is water or an organic solvent other than alcohol. Therefore, alcohol must be added after concentrating the lactic acid solution to a high concentration (e.g., a lactic acid concentration of 90% by mass). In particular, organic solvents other than alcohol (e.g., acetone) may inhibit the reaction during the synthesis of a lactic acid derivative. Therefore, organic solvents other than alcohol must be completely removed from the lactic acid solution. This requires a lot of effort and energy.

[0011] An object of one embodiment of the present disclosure is to provide a method for producing a lactic acid solution, a system for producing a lactic acid solution, and a carbon-based adsorbent composition that can suppress the generation of by-products and produce a lactic acid solution with a low environmental impact. Another problem to be solved by the present invention is to suppress the generation of by-products and to reduce environmental impact. The present invention provides a method for producing a lactic acid derivative, which can produce a lactic acid derivative under a high load. [Means for solving the problem]

[0012] The specific means for achieving the objectives are as follows: <1> contacting lactic acid produced by lactic acid fermentation with a carbon-based adsorbent and / or a carbon-based adsorbent composition to obtain a post-adsorption adsorbent in which the lactic acid is adsorbed onto the carbon-based adsorbent and / or the carbon-based adsorbent composition; contacting the adsorbent with a solvent containing alcohol to extract the lactic acid into the solvent; A method for producing a lactic acid solution, comprising: <2> The post-extraction adsorbent after the extraction step is repeatedly used for the adsorption and extraction steps. <1> A method for producing the lactic acid solution described in <3> the carbon-based adsorbent composition and the post-extraction adsorbent comprise the carbon-based adsorbent and the lactic acid immobilized on the carbon-based adsorbent; The content of the lactic acid immobilized on the carbon-based adsorbent is 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent. <1> or <2> A method for producing the lactic acid solution described in <4> The method further comprises not drying the extracted adsorbent after the extraction step before reuse in the adsorption step, or drying the extracted adsorbent; The temperature of the drying treatment is 120°C or less. <1> ~ <3> 1. A method for producing a lactic acid solution according to any one of the preceding claims. <5> The boiling point of the alcohol at atmospheric pressure is 100°C or less. <1> ~ <4> 1. A method for producing a lactic acid solution according to any one of the preceding claims. <6> Further comprising producing the lactic acid by lactic acid fermentation; The lactic acid fermentation is carried out using fungi. <1> ~ <5> 1. A method for producing a lactic acid solution according to any one of the preceding claims. <7> The amount of the neutralizing agent used in the lactic acid fermentation is 0.20 mol / L or less. <1> ~ <6> 1. A method for producing a lactic acid solution according to any one of the preceding claims. <8> The lactic acid fermentation is carried out using a medium containing the carbon-based adsorbent and / or the carbon-based adsorbent composition. <1> ~ <6> 1. A method for producing a lactic acid solution according to any one of the preceding claims. <9> The aforementioned <1> ~ <8> Producing a lactic acid solution by any one of the methods for producing a lactic acid solution described in any one of the above. synthesizing a lactic acid derivative using the lactic acid solution; A method for producing a lactic acid derivative, comprising: <10> A container and a carbon-based adsorbent and / or a carbon-based adsorbent composition packed in the container; Equipped with The container is configured to be capable of performing a first process and a second process, the first treatment comprises contacting lactic acid produced by lactic acid fermentation with the carbon-based adsorbent and / or carbon-based adsorbent composition to adsorb the lactic acid onto the carbon-based adsorbent and / or carbon-based adsorbent composition to obtain an adsorbed adsorbent; The system for producing a lactic acid solution, wherein the second treatment involves contacting the post-adsorption adsorbent with a solvent containing alcohol to extract the lactic acid into the solvent. <11> The method further includes a lactic acid production vessel for producing the lactic acid by lactic acid fermentation. <10> A system for producing a lactic acid solution according to claim 1. <12> the carbon-based adsorbent composition and the post-extraction adsorbent comprise lactic acid immobilized on the carbon-based adsorbent; The content of the immobilized lactic acid is 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent. <11> A system for producing a lactic acid solution according to claim 1. <13> The lactic acid production vessel further comprises a carbon-based adsorbent and / or a carbon-based adsorbent composition packed therein. <11> or <12> A system for producing a lactic acid solution according to claim 1. <14> A carbon-based adsorbent composition comprising a carbon-based adsorbent and lactic acid immobilized on the carbon-based adsorbent, wherein the content of lactic acid immobilized on the carbon-based adsorbent is 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent. [Effects of the Invention]

[0013] According to the present disclosure, a method for producing a lactic acid solution, a system for producing a lactic acid solution, and a carbon adsorbent composition can be provided that can suppress the generation of by-products and produce a lactic acid solution with a low environmental impact. According to the present disclosure, a method for producing a lactic acid derivative can be provided that can suppress the generation of by-products and produce a lactic acid derivative with a low environmental impact. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating the behavior of lactic acid when a carbon-based adsorbent composition is used repeatedly. [Figure 2] FIG. 2 is a flow diagram of an example of a method for producing a lactic acid solution and a lactic acid derivative according to the present disclosure. [Figure 3] FIG. 3 is a flow diagram of an example of a method for producing a lactic acid solution and a lactic acid derivative according to the present disclosure. [Figure 4] FIG. 4 is a diagram showing an example of a system for producing a lactic acid solution according to the present disclosure. [Figure 5] FIG. 5 is a diagram showing an example of a system for producing a lactic acid solution according to the present disclosure. [Figure 6] FIG. 6 is a graph showing the amount of lactic acid extracted and the lactic acid extraction rate versus the number of uses of the carbon-based adsorbent compositions of Examples 2 to 2-5. [Figure 7]FIG. 7 is a graph showing the mass loss rate of a carbon-based adsorbent composition having lactic acid adsorbed thereon (Reference Example 1) versus the heating temperature, and the mass loss rate of a carbon-based adsorbent having no lactic acid adsorbed thereon (Reference Example 2) versus the heating temperature (Reference Examples 1 and 2). [Figure 8] FIG. 8 is a graph showing the mass loss rate of the carbon-based adsorbent composition (Comparative Example 2) versus the heating time after lactic acid was extracted with acetone. DETAILED DESCRIPTION OF THE INVENTION

[0015] In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples or preparation examples. The term "step" in this specification includes not only an independent step, but also a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved. In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple substances corresponding to each component exist, the content or amount of each component means the total content or amount of the multiple substances, unless otherwise specified.

[0016] (1) Method for producing lactic acid solution The method for producing a lactic acid solution according to the present disclosure includes contacting lactic acid produced by lactic acid fermentation with a carbon-based adsorbent and / or a carbon-based adsorbent composition to obtain a carbon-based adsorbent composition in which the lactic acid is adsorbed onto the carbon-based adsorbent and / or carbon-based adsorbent composition (hereinafter also referred to as an "adsorption step"); and contacting the carbon-based adsorbent composition to which the lactic acid has been adsorbed (hereinafter also referred to as an "adsorbent after adsorption") with a solvent containing alcohol (hereinafter also referred to as an "alcohol solvent") to obtain a pre-adsorbent. and extracting the lactic acid into the solvent (hereinafter also referred to as the "extraction step"). The adsorption step and the extraction step are carried out in this order.

[0017] "Lactic acid fermentation" refers to the reaction in which lactic acid-producing microorganisms metabolize (ferment) sugars to convert them into lactic acid. "Lactic acid-producing microorganisms" refers to microorganisms that produce lactic acid. "Lactic acid" is a compound containing lactic acid monomer as a main component. Lactic acid may contain a lactate salt (e.g., calcium lactate, magnesium lactate, sodium lactate, potassium lactate, ammonium lactate, etc.). One type of lactate salt may be present, or two or more types may be present. Lactic acid may contain a lactic acid oligomer (e.g., lactide, etc.). The content of lactic acid monomer is 50% by mass or more, and may be 60% by mass or more, based on the total amount of lactic acid. The term "carbon-based adsorbent composition" refers to an adsorbent composition containing a carbon-based adsorbent as a main component. The carbon-based adsorbent composition may contain a carbon-based adsorbent and lactic acid immobilized on the carbon-based adsorbent. The term "carbon-based adsorbent" refers to an adsorbent containing carbon as a main component. In other words, the carbon content in the carbon-based adsorbent is 80% by mass or more, or may be 90% by mass or more, or may be 100% by mass, relative to the total amount of the carbon-based adsorbent. Because carbon-based adsorbents adsorb moisture from the atmosphere, the mass of water is not included when calculating the above content.

[0018] The method for producing a lactic acid solution according to the present disclosure has the above-described configuration, and therefore can suppress the generation of by-products and produce a lactic acid solution with a low environmental impact.

[0019] In the method for producing a lactic acid solution of the present disclosure, heating is not required in either the adsorption step or the extraction step. In addition, the extraction solvent is an alcohol solvent. Therefore, the lactic acid solution can be easily concentrated at low temperatures. As a result, the method for producing a lactic acid solution of the present disclosure can suppress denaturation of lactic acid due to heating and produce a lactic acid solution with low environmental impact.

[0020] The method for producing a lactic acid solution disclosed herein uses a carbon-based adsorbent and / or a carbon-based adsorbent composition. When a carbon-based adsorbent composition has been used at least once in the adsorption and extraction steps, any lactic acid that was not completely extracted in the extraction steps is immobilized on the carbon-based adsorbent. Hereinafter, lactic acid immobilized on a carbon-based adsorbent is also referred to as "immobilized lactic acid." Reusing a carbon-based adsorbent composition containing immobilized lactic acid in the adsorption and extraction steps increases the extraction rate of lactic acid. While the reason for this is unclear, it is speculated as follows: Carbon-based adsorbents have strong and weak binding sites. It is believed that immobilizing lactic acid on the strong binding sites of the carbon-based adsorbent allows repeated adsorption and desorption of lactic acid only on the weak binding sites of the carbon-based adsorbent, from which lactic acid is easily desorbed. This is thought to result in a high extraction rate of lactic acid. The more times the carbon-based adsorbent composition is used, the higher the proportion of lactic acid adsorbed to the weak binding sites of the carbon-based adsorbent, from which lactic acid is easily desorbed, and the higher the lactic acid extraction rate. After a certain number of uses of the carbon-based adsorbent composition, most of the lactic acid is fixed to the strong binding sites of the carbon-based adsorbent. Therefore, the lactic acid extraction rate ultimately reaches approximately 100%. The carbon-based adsorbent composition can be reused semi-permanently.

[0021] In the method for producing a lactic acid solution according to the present disclosure, lactic acid can be extracted with a solvent used in the synthesis of a lactic acid derivative. Therefore, the obtained lactic acid solution can be used as is for the synthesis of a lactic acid derivative. If necessary, the obtained lactic acid solution may be concentrated and used as is for the synthesis of a lactic acid derivative.

[0022] In the method for producing a lactic acid solution of the present disclosure, the amount of neutralizing agent can be reduced by using acid-resistant fungi for lactic acid fermentation. Therefore, the generation of by-products (e.g., calcium sulfate, etc.) is suppressed. The carbon-based adsorbent can be reused semi-permanently. Therefore, the amount of waste carbon-based adsorbent is minimized. As a result, the method for producing a lactic acid solution of the present disclosure can produce a lactic acid solution while significantly reducing waste (e.g., calcium sulfate, used regenerating agents, etc.). It is possible.

[0023] The method for producing a lactic acid solution of the present disclosure encompasses a first embodiment of the method for producing a lactic acid solution and a second embodiment of the method for producing a lactic acid solution. In the first embodiment, producing lactic acid by lactic acid fermentation (hereinafter also referred to as the "lactic acid production step") and an adsorption step are carried out independently. In the second embodiment, the lactic acid production step and the adsorption step are carried out simultaneously. Hereinafter, the adsorption step in which the lactic acid production step is carried out simultaneously will also be referred to as the "production-adsorption step." Below, the first and second embodiments will be described in this order.

[0024] (1.1) First aspect The method for producing a lactic acid solution of the first embodiment may further include a lactic acid production step, a first separation step, a second separation step, and a third separation step in addition to the adsorption step and the extraction step. The lactic acid production step, the first separation step, the adsorption step, the second separation step, the extraction step, and the third separation step are performed in this order. If necessary, a desalting treatment, a drying treatment, and a concentration treatment may also be performed. Below, a description will be given of a case where the method for producing a lactic acid solution of the first embodiment further includes a lactic acid production step, a first separation step, a second separation step, and a third separation step in addition to the adsorption step and the extraction step.

[0025] (1.1.1) Lactic acid production process In the lactic acid production step, lactic acid is produced by lactic acid fermentation. Specifically, a microorganism-containing fermentation broth is obtained by carrying out the lactic acid production step. The microorganism-containing fermentation broth contains an aqueous solution containing lactic acid (hereinafter also referred to as a "lactic acid aqueous solution") and solids (e.g., lactic acid-producing microorganisms, a carbon source, etc.).

[0026] (1.1.1.1) Lactic acid-producing microorganisms Lactic acid fermentation uses lactic acid-producing microorganisms. There are no particular limitations on the lactic acid-producing microorganisms, as long as they are microorganisms that produce lactic acid. Lactic acid-producing microorganisms may be natural microorganisms suitable for lactic acid production, or genetically modified microorganisms specifically engineered for lactic acid production. When genetically modified microorganisms are used, the production of organic acids other than lactic acid (e.g., butyric acid, acetic acid, pyruvic acid, succinic acid, formic acid, malic acid, citric acid, malonic acid, propionic acid, ascorbic acid, adipic acid, etc.) tends to be suppressed. Therefore, genetically modified microorganisms are advantageous for adsorption and recovery of lactic acid. Furthermore, genetically modified microorganisms tend to produce lactic acid with high optical activity.

[0027] The type of microorganism is not particularly limited, and may be bacteria (e.g., Escherichia coli or lactic acid bacteria) or fungi (e.g., yeast or mold). One type of microorganism may be used alone, or two or more types may be used in combination. Fungi have high acid tolerance. Therefore, fermentation damage is less likely to occur even in an acidic environment. Examples of natural microorganisms that produce lactic acid include lactic acid bacteria (e.g., Lactobacillus, Leuconostoc, Pediococcus, Lactococcus, or Bifidobacterium), bacteria (e.g., Streptococcus, Enterococcus, Bacillus, Scrotridium, or Sporolactobacillus), or molds (e.g., Rhizopus). The genetically modified microorganism that produces lactic acid is not particularly limited and may be a genetically modified lactic acid-producing yeast. Examples of genetically modified yeast include genetically modified organisms using the genus Saccharomyces (e.g., Saccharomyces cerevisiae) as a host, genetically modified organisms of the genus Candida (e.g., Candida sonorensis), and genetically modified organisms of the genus Kluyveromyces (e.g., Kluyveromyces lactis, Kluyveromyces thermotolerans, or Kluyveromyces marxianus).

[0028] The method for producing a lactic acid solution of the first aspect further comprises producing lactic acid by lactic acid fermentation (i.e., a lactic acid production step), and it is preferable that fungi are used for the lactic acid fermentation. Therefore, the method for producing a lactic acid solution according to the first embodiment can reduce the amount of neutralizing agent used. From the viewpoint of acid resistance, it is more preferable to use yeast or fungi for lactic acid fermentation. From the viewpoint of acid resistance and lactic acid productivity, it is preferable to use genetically modified yeast or fungi for lactic acid fermentation, more preferably genetically modified yeast or genetically modified fungi, and even more preferably genetically modified yeast.

[0029] (1.1.1.2) Culture medium The composition of the medium used for culturing lactic acid-producing microorganisms and lactic acid fermentation is not particularly limited. The medium may contain a carbon source, a nitrogen source, minerals, vitamins, etc. Examples of carbon sources include sugars (e.g., glucose, fructose, sucrose, maltose, etc.). Examples of nitrogen sources include ammonia, ammonium chloride, ammonium acetate, polypeptone, peptone, casamino acids, yeast extract, etc. Examples of inorganic salts include magnesium phosphate, magnesium sulfate, sodium chloride, potassium dihydrogen phosphate, etc. Carbon sources, nitrogen sources, minerals, and vitamins may be used alone or in combination of two or more. The medium used for lactic acid fermentation may further contain a carbon-based adsorbent and / or a carbon-based adsorbent composition described below, or may not contain a carbon-based adsorbent or a carbon-based adsorbent composition. The medium used for lactic acid fermentation may contain a neutralizing agent described below, or may not contain a neutralizing agent.

[0030] (1.1.1.3) Neutralizer The amount of neutralizing agent used in lactic acid fermentation is preferably 0.20 mol / L or less. When a neutralizing agent is used in lactic acid fermentation, the amount of lactic acid produced increases, but there is a risk of an increase in by-products generated during desalination of lactate and an increase in the energy required for desalination. By using the neutralizing agent in an amount of 0.20 mol / L or less, the amount of by-products generated and the increase in the energy required can be suppressed. The amount of neutralizing agent used is more preferably 0.16 mol / L or less, and even more preferably 0.12 mol / L or less, from the viewpoint of reducing by-products generated during desalination of lactate and reducing energy consumption. The amount of neutralizing agent used may be 0.00 mol / L. From the viewpoint of lactic acid production, the amount of neutralizing agent used is preferably 0.01 mol / L or more, and more preferably 0.02 mol / L or more.

[0031] Examples of the neutralizing agent include calcium carbonate, calcium hydroxide, magnesium carbonate, magnesium hydroxide, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium hydroxide, ammonia, etc. One type of neutralizing agent may be used alone, or two or more types may be used in combination.

[0032] When a neutralizing agent is used in lactic acid fermentation, it is preferable to perform a desalting treatment of lactate. The desalting treatment may be performed before the first separation step or the adsorption step, or after the extraction step. Examples of desalting methods include adding an acid in an amount equal to the amount of lactate to a solution containing lactate.

[0033] (1.1.1.4) Lactic acid fermentation conditions The pH in lactic acid fermentation is not particularly limited and is selected appropriately depending on the type of lactic acid-producing microorganism. For example, in neutralized fermentation involving neutralization with a neutralizing agent, the pH may be set to 2.0 to 10.0. In non-neutralized fermentation not involving neutralization with a neutralizing agent, the pH may be set to 1.0 to 8.0.

[0034] Other conditions for lactic acid fermentation (such as temperature or aeration) are appropriately selected depending on the type of lactic acid-producing microorganism. The culture method for lactic acid fermentation is not particularly limited, and may be, for example, batch culture, semi-batch culture, continuous culture, or a combination thereof. The method of feeding or stirring the lactic acid-producing microorganism is selected depending on the type of lactic acid-producing microorganism. During the cultivation, antibiotics (e.g., ampicillin, tetracycline, etc.) may be added to the medium as needed.

[0035] (1.1.2) First separation step In the first separation step, the microorganism-containing fermentation liquor obtained by carrying out the lactic acid production step is subjected to solid-liquid separation, whereby solids (e.g., lactic acid-producing microorganisms) are separated from the microorganism-containing fermentation liquor to obtain an aqueous lactic acid solution.

[0036] When a neutralizing agent is used in the lactic acid production step, a desalting treatment may be carried out before the first separation step. Examples of desalting methods include a method in which an acid in an amount equal to the amount of lactate contained in the microorganism-containing fermentation liquor is added to the microorganism-containing fermentation liquor.

[0037] The method for performing solid-liquid separation on the microorganism-containing fermentation liquor (hereinafter also referred to as "solid-liquid separation method") is not particularly limited and may be any known method, such as filtration, centrifugation, etc. Water may be added to the aqueous lactic acid solution as needed.

[0038] (1.1.3) Adsorption process In the adsorption step, the aqueous lactic acid solution is contacted with a carbon-based adsorbent and / or a carbon-based adsorbent composition to adsorb lactic acid contained in the aqueous lactic acid solution onto the carbon-based adsorbent and / or the carbon-based adsorbent composition. This produces a first mixture. The first mixture contains the adsorbent after adsorption and a solution derived from the aqueous lactic acid solution (hereinafter also referred to as "used liquid").

[0039] When a neutralizing agent is used in the lactic acid production step, a desalination treatment may be carried out before the adsorption step. Examples of desalination methods include adding an acid in an amount equal to the amount of lactate salt contained in the aqueous lactic acid solution to the aqueous lactic acid solution. To adjust the concentration of the aqueous lactic acid solution, a concentration treatment of the aqueous lactic acid solution may be carried out before the adsorption step.

[0040] The lactic acid concentration of the lactic acid aqueous solution used in the adsorption step is preferably 10 g / L to 300 g / L, more preferably 25 g / L to 250 g / L, and even more preferably 50 g / L to 225 g / L. When the lactic acid aqueous solution contains a lactate, the molar amount of the lactate is added to the molar amount of the lactic acid monomer to calculate the lactic acid concentration. When the lactic acid aqueous solution contains a lactic acid oligomer, the mass of the lactic acid oligomer is added to the mass of the lactic acid monomer to calculate the lactic acid concentration. With respect to the lactic acid contained in the aqueous lactic acid solution, the content of lactic acid monomer contained in the lactic acid is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, relative to the total amount of lactic acid. The total mass of the carbonaceous adsorbent and the carbonaceous adsorbent composition used in the adsorption step is preferably 100 g to 1000 g, more preferably 150 g to 800 g, even more preferably 200 g to 700 g, and particularly preferably 300 g to 600 g, relative to 1 L of the aqueous lactic acid solution.

[0041] (1.1.3.1) Carbon-based adsorbents and carbon-based adsorbent compositions The carbon-based adsorbent composition contains a carbon-based adsorbent. Examples of carbon-based adsorbents include activated carbon, graphite, and charcoal. From the viewpoint of lactic acid adsorption and lactic acid extractability when contacted with a solvent containing alcohol, the carbon-based adsorbent is most preferably activated carbon. The form of the carbon-based adsorbent is not particularly limited, and examples include powder, granules, honeycomb, crushed, fibrous, and sheet forms. "Granular" refers to powder formed into a spherical, cylindrical, or discoid shape, and preferably has a total length of 0.5 mm or more. The size of the powdered carbon-based adsorbent is not particularly limited, and may be 400 mesh or less, or 325 mesh or less. From the viewpoint of operability in the adsorption and extraction steps, and ease of separation from solids other than the carbon-based adsorbent (such as lactic acid-producing microorganisms), the form of the carbon-based adsorbent is preferably granular. The carbon-based adsorbent is preferably in at least one of granular, crushed, fibrous, and sheet form, more preferably crushed or granular, and even more preferably granular. The total length of the granular form is preferably 0.5 mm to 30 mm, more preferably 1.0 mm to 25 mm, and even more preferably 1.5 mm to 20 mm, from the viewpoints of operability in the adsorption step and extraction step, adsorption ability of lactic acid and lactate, and extractability of lactic acid and lactate when contacted with a solvent containing alcohol. The carbon-based adsorbent may be a known carbon-based adsorbent or may be a product. The content of the carbon-based adsorbent in the carbon-based adsorbent composition is not particularly limited, but is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, relative to the total amount of the carbon-based adsorbent composition. The upper limit of the content of the carbon-based adsorbent is not particularly limited, but the content of the carbon-based adsorbent is preferably 99% by mass or less, and more preferably 97% by mass or less.

[0042] The carbonaceous adsorbent composition may contain immobilized lactic acid, which will be described later. The content of the immobilized lactic acid is preferably 1% by mass to 15% by mass, and more preferably 3% by mass to 10% by mass, relative to 100% by mass of the carbonaceous adsorbent.

[0043] In addition to the carbon-based adsorbent and immobilized lactic acid, the carbon-based adsorbent composition may contain lactic acid that can be extracted from the carbon-based adsorbent composition with an alcohol solvent and components contained in the culture medium (e.g., microorganisms, carbon source, nitrogen source, minerals, vitamins, etc.).

[0044] The carbon-based adsorbent adsorbs moisture from the atmosphere, but does not affect the adsorption and extraction of lactic acid and is easily evaporated by drying. Therefore, the mass of water adsorbed on the carbon-based adsorbent is not included in the content of substances contained in the carbon-based adsorbent composition. After the extraction step described below is performed, an alcohol solvent described below adheres to the surface of the post-extraction adsorbent, but the alcohol solvent does not affect the adsorption and extraction of lactic acid and is easily evaporated by drying. Therefore, the mass of the alcohol solvent adhered to the surface of the carbon-based adsorbent is not included in the content of substances contained in the carbon-based adsorbent composition.

[0045] (1.1.3.2) Contact method The method for contacting the aqueous lactic acid solution with the carbon-based adsorbent and / or carbon-based adsorbent composition is not particularly limited and can be appropriately selected depending on the form of the carbon-based adsorbent and carbon-based adsorbent composition. For example, a method in which the carbon-based adsorbent and / or carbon-based adsorbent composition is immersed in the aqueous lactic acid solution and allowed to stand at room temperature (15°C to 35°C) can be used. If necessary, the aqueous lactic acid solution may be heated to a temperature below 100°C. The aqueous lactic acid solution in which the carbon-based adsorbent and / or carbon-based adsorbent composition has been immersed may be stirred. The carbon-based adsorbent and / or carbon-based adsorbent composition in the aqueous lactic acid solution may be stirred. The contact time between the aqueous lactic acid solution and the carbon-based adsorbent and / or carbon-based adsorbent composition is not particularly limited, but is preferably 2 to 96 hours, more preferably 3 to 48 hours, and even more preferably 4 to 24 hours.

[0046] (1.1.4) Second separation step In the second separation step, the first mixed liquid is subjected to solid-liquid separation, whereby the used liquid is separated from the first mixed liquid and a post-adsorption adsorbent is obtained.

[0047] Examples of the method for performing solid-liquid separation on the first mixed liquid include the same methods as those exemplified as the solid-liquid separation method.

[0048] The adsorption step and the second separation step may be carried out two or more times to increase the amount of lactic acid adsorbed.

[0049] (1.1.4.1) Reuse of used liquid The used liquid separated in the second separation step may be reused as the aqueous lactic acid solution in the adsorption step. The used liquid is preferably subjected to a concentration treatment before being reused as the aqueous lactic acid solution in the adsorption step. This increases the lactic acid concentration in the used liquid, making it easier for lactic acid to be adsorbed onto the carbon-based adsorbent and the carbon-based adsorbent composition. The concentration treatment method is not particularly limited, and any known method may be used.

[0050] (1.1.5) Extraction process In the extraction step, the post-adsorption adsorbent is contacted with an alcohol solvent to extract lactic acid adsorbed on the post-adsorption adsorbent into the alcohol solvent. This results in a second mixture. The second mixture contains a lactic acid solution and a carbon-based adsorbent composition (i.e., post-extraction adsorbent) obtained by desorbing lactic acid from the post-adsorption adsorbent. The lactic acid solution contains lactic acid and an alcohol solvent.

[0051] The volume of the alcohol solvent used in the extraction step is preferably 50 mL to 1000 mL, more preferably 100 mL to 800 mL, and even more preferably 150 mL to 600 mL per 100 g of carbon-based adsorbent contained in the adsorbent after adsorption.

[0052] The lactic acid solution may contain water. If it is desired to reduce the water content of the lactic acid solution, the adsorbent after adsorption may be subjected to a drying treatment before carrying out the extraction step. The drying method is not particularly limited, and any known method (e.g., air drying, heat drying, hot air drying, vacuum drying, suction drying, etc.) may be used. Lactic acid vaporizes at temperatures higher than 120°C. Therefore, the temperature of the drying treatment is preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower.

[0053] (1.1.5.1) Alcohol solvent The alcohol solvent contains an alcohol. The alcohol is not particularly limited and is appropriately selected depending on the type of the desired lactic acid derivative, and examples thereof include a compound represented by the following formula (1) (hereinafter also referred to as "alcohol (1)"):

[0054] [ka]

[0055] In formula (1), R is not particularly limited, but is preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group having 1 to 10 carbon atoms may be linear or branched. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a 2-methyl-2-butyl group, a 3-methylbutyl group, a 1-methylpentyl group, a neopentyl group, a 1-ethylpropyl group, a hexyl group, a 3,3-dimethylbutyl group, a heptyl group, a methylheptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, and a decyl group.

[0056] Examples of the alcohol (1) in which R is an alkyl group having 1 to 10 carbon atoms include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, pentyl alcohol, 3-pentanol, 2-methyl-2-butyl alcohol, 3-methylbutyl alcohol, 1-methylpentyl alcohol, neopentyl alcohol, 1-ethylpropyl alcohol, hexyl alcohol, and 3,3-dimethylbutyl alcohol. Examples of the alcohol include ethyl alcohol, heptyl alcohol, methylheptyl alcohol, 2-ethylhexyl alcohol, octyl alcohol, nonyl alcohol, and decyl alcohol. Other examples of the alcohol (1) include allyl alcohol, benzyl alcohol, cyclohexanol, furfuryl alcohol, chloroethyl alcohol, 2-methoxymethyl alcohol, 2-ethoxyethyl alcohol, 2-butoxyethyl alcohol, 2-(2-methoxyethoxy)ethyl alcohol, 2-(2-ethoxyethoxy)ethyl alcohol, 2-(2-butoxyethoxy)ethyl alcohol, and triethyl alcoholamine.

[0057] The boiling point of the alcohol at atmospheric pressure is preferably 100°C or lower. This allows the lactic acid solution to be concentrated at a lower temperature than water. Examples of alcohols having a boiling point of 100°C or lower at atmospheric pressure include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and allyl alcohol. From the viewpoints of the effect on the human body, ease of concentration, and extractability of lactic acid, ethyl alcohol, isopropyl alcohol, or tert-butyl alcohol is preferred, ethyl alcohol or isopropyl alcohol is more preferred, and ethyl alcohol is even more preferred.

[0058] The alcohol solvent may consist solely of alcohol. The alcohol solvent may contain, in addition to alcohol, an organic solvent different from alcohol (e.g., chloroform) or water. The alcohol content in the alcohol solvent is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 98% by mass or more, based on the total amount of the alcohol solvent. The alcohol may be produced from plant-derived raw materials.

[0059] (1.1.5.2) Contact method The method for contacting the adsorbent with the alcohol solvent after adsorption is not particularly limited and can be appropriately selected depending on the form of the carbon-based adsorbent and the carbon-based adsorbent composition, etc. For example, the adsorbent after adsorption may be immersed in the alcohol solvent and allowed to stand at room temperature (15°C to 35°C). If necessary, the alcohol solvent may be heated to a temperature below the boiling point of the alcohol solvent. The alcohol solvent in which the adsorbent after adsorption is immersed may be stirred. The adsorbent after adsorption in the alcohol solvent may be stirred. The contact time between the adsorbent after adsorption and the alcohol solvent is not particularly limited, but is preferably 2 hours to 96 hours, more preferably 3 hours to 48 hours, and even more preferably 4 hours to 24 hours.

[0060] (1.1.6) Third separation step In the third separation step, the second mixture is subjected to solid-liquid separation, whereby the post-extraction adsorbent is separated from the second mixture, and a lactic acid solution is obtained.

[0061] Examples of the method for performing solid-liquid separation on the second mixed liquid include the same methods as those exemplified as the solid-liquid separation method.

[0062] The content of lactic acid in the lactic acid solution after the third separation step is appropriately selected depending on the application of the lactic acid solution, and may be adjusted by concentration, etc. When the lactic acid solution is used to synthesize a lactic acid derivative, the content of lactic acid in the lactic acid solution may be 0.1% by mass to 50% by mass, or 1% by mass to 40% by mass, relative to the total amount of the lactic acid solution. When the lactic acid solution contains a lactate salt, the lactic acid concentration is calculated by adding the molar amount of the lactate salt to the molar amount of lactic acid monomer. When the lactic acid solution contains a lactic acid oligomer, the mass of the lactic acid oligomer is added to the mass of the lactic acid monomer to calculate the lactic acid concentration. The lactic acid solution may contain water.

[0063] When the lactic acid solution contains lactate, it may be subjected to a desalting treatment, for example, by adding an acid in an amount equal to the amount of lactate contained in the lactic acid solution.

[0064] Regarding the lactic acid contained in the lactic acid solution, the contents of lactic acid monomers and lactic acid oligomers contained in the lactic acid are not particularly limited and are appropriately selected depending on the application. To reduce the content of lactic acid oligomers, the lactic acid solution can be heated at 60°C to 120°C, for example, to decompose the lactic acid oligomers into lactic acid monomers.

[0065] The extraction step and the third separation step may be carried out two or more times to increase the extraction rate of lactic acid.

[0066] (1.1.6.1) Reuse of the adsorbent after extraction It is preferable to repeatedly use the carbon-based adsorbent composition (i.e., the extracted adsorbent) after the extraction (i.e., the extraction step) for the adsorption (i.e., the adsorption step) and the extraction (i.e., the extraction step). This minimizes the amount of waste carbon-based adsorbent composition. In the extracted adsorbent after the first extraction step, lactic acid is immobilized at the strong binding sites of the carbon-based adsorbent. Therefore, in the second and subsequent adsorption steps, a higher proportion of lactic acid is adsorbed at the weak binding sites of the carbon-based adsorbent, from which lactic acid is easily desorbed. As a result, the lactic acid extraction rate increases. After the number of uses of the extracted adsorbent reaches a certain level, lactic acid is immobilized at most of the strong binding sites of the carbon-based adsorbent. Therefore, the lactic acid extraction rate ultimately reaches approximately 100%.

[0067] The first embodiment of the method for producing a lactic acid solution includes not performing a drying treatment on the carbon-based adsorbent composition (i.e., the post-extraction adsorbent) after the extraction (i.e., the extraction step) before reuse in the adsorption (i.e., the adsorption step), or performing a drying treatment on the post-extraction adsorbent, and the drying treatment is preferably performed at a temperature of 120°C or lower. After the extraction step, the surface of the post-extraction adsorbent is in a state where the alcohol solvent is attached (hereinafter also referred to as a "solvent-attached state"). Even if the adsorption step is performed when the surface of the post-extraction adsorbent is in a solvent-attached state, this does not affect the adsorption of lactic acid to the post-extraction adsorbent (the amount of lactic acid adsorbed does not change). From the viewpoint of recovering the alcohol solvent attached to the surface of the post-extraction adsorbent, it is preferable to perform a drying treatment, and the drying treatment temperature is preferably 120°C or lower. Lactic acid evaporates at temperatures higher than 120°C. Therefore, by drying the post-extraction adsorbent at a temperature of 120°C or lower, the post-extraction adsorbent can be dried without evaporating the lactic acid immobilized on the post-extraction adsorbent. The temperature for the drying treatment is preferably 100°C or lower, more preferably 80°C or lower, from the viewpoint of suppressing the evaporation of immobilized lactic acid and reducing energy consumption. The method of drying is not particularly limited, and may be any known method (for example, air drying, heat drying, hot air drying, vacuum drying, suction drying, etc.).

[0068] (1.1.6.2) Carbon-based adsorbent composition and immobilized lactic acid The carbon-based adsorbent composition contains a carbon-based adsorbent and lactic acid immobilized on the carbon-based adsorbent (i.e., immobilized lactic acid), and the content of the lactic acid immobilized on the carbon-based adsorbent (i.e., immobilized lactic acid) is preferably 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent. This allows lactic acid to be adsorbed and desorbed only at weak binding sites of the carbon-based adsorbent from which lactic acid is easily desorbed. As a result, the extraction rate of lactic acid is increased. The content of immobilized lactic acid is more preferably 3% by mass to 10% by mass. The contents of lactic acid monomers, lactic acid oligomers, and lactate salts contained in the immobilized lactic acid are not particularly limited. The immobilized lactic acid is lactic acid that does not desorb from the carbon-based adsorbent composition even when extracted with an alcohol solvent, etc. An example of a method for calculating the content of immobilized lactic acid contained in the carbon-based adsorbent composition is as follows: The following is described below. The amount of immobilized lactic acid [g] is calculated from the difference between the amount of lactic acid [g] adsorbed onto the carbon-based adsorbent composition in the adsorption step performed on the carbon-based adsorbent composition and the amount of lactic acid [g] desorbed from the carbon-based adsorbent composition in the extraction step. The content of immobilized lactic acid [% by mass] is calculated from the amount of immobilized lactic acid [g] and the mass [g] of the carbon-based adsorbent contained in the carbon-based adsorbent composition. The content of immobilized lactic acid may be calculated from the loss on heating of the carbon-based adsorbent composition. An example of a specific method is described below. An alcohol solvent is added to the carbon-based adsorbent composition, and the mixture is left to stand at 30°C for 8 hours. The mixture is then filtered through a filter to separate the carbon-based adsorbent composition from the alcohol solvent. The resulting carbon-based adsorbent composition is subjected to a first drying treatment at a temperature of 100°C or lower. The mass [g] of the carbon-based adsorbent composition after the first drying treatment (i.e., the carbon-based adsorbent composition after water and alcohol removal) is measured. The carbon-based adsorbent composition subjected to the first drying treatment is then subjected to a second drying treatment at 200°C. The difference between the mass [g] of the carbon-based adsorbent composition after the first heating treatment and the mass [g] of the carbon-based adsorbent composition after the second heating treatment is defined as the amount of immobilized lactic acid [g]. The mass [g] of the carbon-based adsorbent composition after the second heating treatment is defined as the mass [g] of the carbon-based adsorbent. The amount of immobilized lactic acid [g] and the mass [g] of the carbon-based adsorbent are used to calculate the content [mass%] of immobilized lactic acid. If the carbon-based adsorbent composition is an adsorbent after extraction, the drying treatment may be performed without adding and separating the alcohol solvent, and the content [mass%] of immobilized lactic acid may be calculated. A differential thermobalance may be used to perform the above measurement.

[0069] As shown in Figure 1, carbon-based adsorbents are typically porous materials. Carbon-based adsorbents are typically thought to have multiple strong-binding sites where lactic acid is easily immobilized and multiple weak-binding sites where lactic acid is less likely to be immobilized. The strong-binding sites are likely to be formed deep within each of the multiple pores of the carbon-based adsorbent. Immobilized lactic acid bound to the strong-binding sites of the carbon-based adsorbent is unlikely to be released from the carbon-based adsorbent even after an extraction process is performed. In other words, the immobilized lactic acid may be semi-permanently immobilized on the carbon-based adsorbent. On the other hand, lactic acid bound to the weak-binding sites of the carbon-based adsorbent is likely to be released from the carbon-based adsorbent after an extraction process is performed.

[0070] Immobilized lactic acid vaporizes at temperatures higher than 120° C. and completely vaporizes at 200° C. Therefore, when a carbon-based adsorbent composition containing immobilized lactic acid is dried, the temperature for the drying treatment is preferably 120° C. or lower, more preferably 100° C. or lower, and even more preferably 80° C. or lower.

[0071] (1.2) Second aspect The method for producing a lactic acid solution of the second aspect may further include a fourth separation step and a fifth separation step in addition to the production adsorption step and the extraction step. The production adsorption step, the fourth separation step, the extraction step, and the fifth separation step are performed in this order. If necessary, a desalting treatment, a drying treatment, and a concentration treatment may also be performed. Below, a case where the method for producing a lactic acid solution of the second aspect further includes the fourth separation step and the fifth separation step in addition to the production adsorption step and the extraction step will be described.

[0072] (1.2.1) Production adsorption process In the production-adsorption step, lactic acid is produced by lactic acid fermentation, and simultaneously the lactic acid is contacted with a carbon-based adsorbent and / or a carbon-based adsorbent composition to adsorb the lactic acid onto the carbon-based adsorbent and / or the carbon-based adsorbent composition. This results in an adsorbent-containing fermentation liquor. The adsorbent-containing fermentation liquor contains a liquid (water, lactic acid that was not completely adsorbed by the carbon-based adsorbent, etc.), a carbon-based adsorbent composition with lactic acid adsorbed (hereinafter also referred to as the "adsorbent after adsorption" or "adsorbent after fermentation"), and other solid components (e.g., lactic acid-producing microorganisms, a carbon source, etc.).

[0073] (1.2.1.1) Lactic acid-producing microorganisms Lactic acid fermentation is carried out using a lactic acid-producing microorganism. Examples of lactic acid-producing microorganisms include those similar to those exemplified above.

[0074] The method for producing a lactic acid solution of the second aspect further comprises producing lactic acid by lactic acid fermentation (i.e., a lactic acid production step), and preferably uses fungi for the lactic acid fermentation, thereby reducing the amount of neutralizing agent used and enabling the production of lactic acid with high optical activity. From the viewpoint of acid resistance, it is more preferable to use yeast or fungi for lactic acid fermentation. From the viewpoint of acid resistance and lactic acid productivity, it is preferable to use genetically modified yeast or fungi for lactic acid fermentation, more preferably genetically modified yeast or genetically modified fungi, and even more preferably genetically modified yeast.

[0075] (1.2.1.2) Culture medium The medium composition used for culturing the lactic acid-producing microorganism and for lactic acid fermentation is not particularly limited, and examples thereof include the same medium compositions as those exemplified in the first embodiment.

[0076] (1.2.1.3) Lactic acid fermentation conditions Lactic acid fermentation conditions include the same as those exemplified as the conditions for lactic acid fermentation in the first embodiment.

[0077] (1.2.1.4) Carbon-based adsorbents and carbon-based adsorbent compositions Lactic acid fermentation preferably uses a medium containing a carbon-based adsorbent and / or a carbon-based adsorbent composition. This allows lactic acid to be produced by lactic acid fermentation while simultaneously contacting the lactic acid with the carbon-based adsorbent and / or the carbon-based adsorbent composition, resulting in the lactic acid being adsorbed onto the carbon-based adsorbent and / or the carbon-based adsorbent composition. Additionally, the use of a medium containing a carbon-based adsorbent and / or a carbon-based adsorbent composition for lactic acid fermentation increases the amount of lactic acid produced without the use of a neutralizing agent. While the reason for this increase in lactic acid production is unclear, it is speculated as follows: The adsorption of lactic acid produced during lactic acid fermentation to the carbon-based adsorbent and the carbon-based adsorbent composition inhibits a decrease in pH of the microorganism-containing fermentation broth. This is thought to be why the amount of lactic acid produced increases. The total amount of the carbon-based adsorbent and the carbon-based adsorbent composition used is not particularly limited, and may be 50 g / L to 500 g / L, or 100 g / L to 400 g / L, relative to the total liquid volume of the culture medium excluding the carbon-based adsorbent.

[0078] Examples of the carbon-based adsorbent and carbon-based adsorbent composition include the same as those exemplified as the carbon-based adsorbent and carbon-based adsorbent composition of the first embodiment.

[0079] When a medium containing a carbon-based adsorbent and / or a carbon-based adsorbent composition is used in the production adsorption step, the post-fermentation adsorbent has lactic acid adsorbed thereon. Therefore, it is preferable that the post-fermentation adsorbent separated as a solid by the solid-liquid separation is also subjected to the extraction step described below.

[0080] (1.2.1.5) Neutralizer In the second embodiment, the carbon-based adsorbent and carbon-based adsorbent composition contained in the lactic acid fermentation medium perform the same function as a neutralizer, so it is preferable not to use a neutralizer. A neutralizer may be used in combination to further increase lactic acid production. The amount of neutralizer used is preferably 0.20 mol / L or less, more preferably 0.16 mol / L or less, even more preferably 0.12 mol / L, and particularly preferably 0.00 mol / L (i.e., no neutralizer is used) from the viewpoint of reducing by-products generated and energy consumption during desalting of lactate.

[0081] Examples of the neutralizing agent include the same neutralizing agents as those exemplified in the first embodiment.

[0082] When a neutralizing agent is used in the lactic acid fermentation, it is preferable to perform a desalting treatment of the lactate. The desalting treatment may be performed after the extraction step. Examples of the desalting treatment method include adding an acid in an amount equal to the amount of lactate to a solution containing lactate.

[0083] (1.2.1.6) Contact method In the second embodiment, since the medium for lactic acid fermentation contains a carbon-based adsorbent and / or a carbon-based adsorbent composition, the lactic acid produced by lactic acid fermentation naturally comes into contact with the carbon-based adsorbent and / or the carbon-based adsorbent composition, and therefore the contact conditions between the lactic acid and the carbon-based adsorbent and / or the carbon-based adsorbent composition are the same as the conditions for the lactic acid fermentation.

[0084] (1.2.2) Fourth separation step In the fourth separation step, the adsorbent-containing fermentation liquor is subjected to solid-liquid separation. This separates the solids from the adsorbent-containing fermentation liquor to obtain the post-fermentation adsorbent and an aqueous lactic acid solution. The aqueous lactic acid solution is used in the adsorption step.

[0085] Methods for performing solid-liquid separation on the adsorbent-containing fermentation broth include the same methods as those exemplified as solid-liquid separation methods.

[0086] (1.2.3) Extraction process In the extraction step, the post-fermentation adsorbent is contacted with an alcohol solvent to extract the lactic acid adsorbed on the post-fermentation adsorbent into the alcohol solvent. This results in a third mixture. The third mixture contains a lactic acid solution and a carbon-based adsorbent composition (i.e., post-extraction adsorbent) obtained by desorbing lactic acid from the post-fermentation adsorbent. The lactic acid solution contains lactic acid and an alcohol solvent.

[0087] The volume of the alcohol solvent used in the extraction step is preferably 50 mL to 1000 mL, more preferably 100 mL to 800 mL, and even more preferably 150 mL to 600 mL per 100 g of carbon-based adsorbent contained in the adsorbent after adsorption.

[0088] The lactic acid solution may contain water. If it is desired to reduce the water content of the lactic acid solution, the post-fermentation adsorbent may be subjected to a drying treatment before the extraction step. The drying method is not particularly limited, and any known method (e.g., air drying, heat drying, hot air drying, suction drying, etc.) may be used. Lactic acid evaporates at temperatures higher than 120°C. Therefore, the drying temperature is preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower.

[0089] (1.2.3.1) Alcohol solvent Examples of the alcohol solvent include the same ones as those exemplified as the alcohol solvent of the first embodiment.

[0090] The boiling point of the alcohol at atmospheric pressure is preferably 100°C or lower. This allows the lactic acid solution to be concentrated at a lower temperature than water. Examples of alcohols having a boiling point of 100°C or lower at atmospheric pressure include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and allyl alcohol. From the viewpoints of the effect on the human body, ease of concentration, and extractability of lactic acid, ethyl alcohol, isopropyl alcohol, or tert-butyl alcohol is preferred, ethyl alcohol or isopropyl alcohol is more preferred, and ethyl alcohol is even more preferred.

[0091] (1.2.3.2) Contact method The method for contacting the fermented adsorbent with the alcohol solvent is not particularly limited and may be appropriately selected depending on the form of the carbon-based adsorbent composition, etc., and examples thereof include a method in which the fermented adsorbent is immersed in the alcohol solvent and allowed to stand at room temperature (15°C to 35°C). If necessary, the alcohol solvent may be heated to a temperature below the boiling point of the alcohol solvent. The alcohol solvent in which the fermented adsorbent is immersed may be stirred. The fermented adsorbent in the alcohol solvent may be stirred. The contact time between the fermented adsorbent and the alcohol solvent is not particularly limited, but is preferably 2 to 96 hours, more preferably 3 to 48 hours, and even more preferably 4 to 24 hours.

[0092] (1.2.4) Fifth separation step In the fifth separation step, the third mixture is subjected to solid-liquid separation, whereby the post-extraction adsorbent is separated from the third mixture, and a lactic acid solution is obtained.

[0093] Examples of the method for performing solid-liquid separation on the third mixed liquid include the same methods as those exemplified as the solid-liquid separation method.

[0094] The content of lactic acid in the lactic acid solution after the fifth separation step is appropriately selected depending on the application of the lactic acid solution, and may be adjusted by concentration, etc. When the lactic acid solution is used to synthesize a lactic acid derivative, the content of lactic acid in the lactic acid solution may be 0.1% by mass to 50% by mass, or 1% by mass to 40% by mass, relative to the total amount of the lactic acid solution. When the lactic acid solution contains a lactate salt, the lactic acid concentration is calculated by adding the molar amount of the lactate salt to the molar amount of lactic acid monomer. When the lactic acid solution contains a lactic acid oligomer, the lactic acid concentration is calculated by adding the mass of the lactic acid oligomer to the mass of the lactic acid monomer. The lactic acid solution may contain water.

[0095] When the lactic acid solution contains lactate, it may be subjected to a desalting treatment, for example, by adding an acid in an amount equal to the amount of lactate contained in the lactic acid solution.

[0096] Regarding the lactic acid contained in the lactic acid solution, the contents of lactic acid monomers and lactic acid oligomers contained in the lactic acid are not particularly limited and are appropriately selected depending on the application. To reduce the content of lactic acid oligomers, the lactic acid solution can be heated at 60°C to 120°C, for example, to decompose the lactic acid oligomers into lactic acid monomers.

[0097] Lactic acid-fermenting microorganisms and the like are usually attached to the post-fermentation adsorbent. In the extraction step, the lactic acid-fermenting microorganisms and the like attached to the post-fermentation adsorbent are released into the alcohol solvent. If the carbon-based adsorbent and carbon-based adsorbent composition used in the lactic acid production step are in a specific form (e.g., granular, crushed, fibrous, or sheet form), the post-extraction adsorbent and the lactic acid-fermenting microorganisms and the like can be easily separated in the fifth separation step. A specific example is described below. When the third mixed liquid is filtered through a filter, the lactic acid-fermenting microorganisms and the like deposit on the filter. The post-extraction adsorbent having the specific form contained in the third mixed liquid does not pass through the filter and does not deposit on the filter. Therefore, after filtration through the filter, the post-extraction adsorbent and the lactic acid-fermenting microorganisms and the like can be easily separated by replacing the filter on which the lactic acid-fermenting microorganisms and the like have deposited, or by transferring only the post-extraction adsorbent to another container.

[0098] The extraction step and the fifth separation step may be carried out two or more times to increase the extraction rate of lactic acid.

[0099] (1.2.4.1) Reuse of adsorbent after extraction The carbon-based adsorbent composition (i.e., It is preferable to repeatedly use the post-extraction adsorbent (post-extraction adsorbent) in the adsorption (i.e., production adsorption process). This minimizes the amount of waste carbon-based adsorbent composition. After the first extraction process, lactic acid is immobilized at the strong binding sites of the post-extraction adsorbent. Therefore, in the second and subsequent adsorption and extraction processes, a higher proportion of lactic acid is adsorbed at the weak binding sites of the carbon-based adsorbent, from which lactic acid is easily desorbed. As a result, the lactic acid extraction rate increases. After the post-extraction adsorbent has been used a certain number of times, lactic acid is immobilized at most of the strong binding sites. Therefore, the lactic acid extraction rate ultimately reaches approximately 100%.

[0100] The second embodiment of the method for producing a lactic acid solution includes either not drying the carbon-based adsorbent composition (i.e., the post-extraction adsorbent) after the extraction (i.e., the extraction step) before reuse in the adsorption (i.e., the production adsorption step), or drying the post-extraction adsorbent, and the drying temperature is preferably 120°C or lower. After the extraction step, the surface of the post-extraction adsorbent is in a state where the alcohol solvent is attached (i.e., a solvent-attached state). Even if the production adsorption step is performed when the surface of the post-extraction adsorbent is in a solvent-attached state, this does not affect the adsorption of lactic acid to the post-extraction adsorbent (the amount of lactic acid adsorbed does not change). From the viewpoints of recovering the alcohol solvent attached to the surface of the post-extraction adsorbent and reducing the impact on lactic acid fermentation, it is preferable to perform a drying process, and the drying temperature is preferably 120°C or lower. Lactic acid evaporates at temperatures higher than 120°C. Therefore, by drying the post-extraction adsorbent at a temperature of 120°C or lower, the post-extraction adsorbent can be dried without evaporating the lactic acid immobilized on the post-extraction adsorbent. The temperature for the drying treatment is preferably 100°C or lower, more preferably 80°C or lower, from the viewpoint of suppressing the evaporation of immobilized lactic acid and suppressing energy consumption. The method of drying is not particularly limited, and may be any known method (for example, air drying, heat drying, hot air drying, vacuum drying, suction drying, etc.).

[0101] (1.2.4.2) Carbon-based adsorbent composition and immobilized lactic acid The carbon-based adsorbent composition contains a carbon-based adsorbent and lactic acid immobilized on the carbon-based adsorbent (i.e., immobilized lactic acid), and the content of lactic acid immobilized on the carbon-based adsorbent (i.e., immobilized lactic acid) is preferably 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent composition. This allows lactic acid to be adsorbed and desorbed only at weak binding sites of the carbon-based adsorbent from which lactic acid is easily desorbed. As a result, the extraction rate of lactic acid is high. The content of immobilized lactic acid is preferably 3% by mass to 10% by mass. The contents of lactic acid monomers, lactic acid oligomers, and lactate salts contained in the immobilized lactic acid are not particularly limited. The carbon-based adsorbent adsorbs moisture from the atmosphere, but does not affect the adsorption and extraction of lactic acid and is easily evaporated by drying. Therefore, the mass of water adsorbed on the carbon-based adsorbent is not included in the content of substances contained in the carbon-based adsorbent composition. After the extraction process, an alcohol solvent adheres to the surface of the post-extraction adsorbent, but the alcohol solvent does not affect the adsorption and extraction of lactic acid and is easily evaporated by drying. Therefore, the mass of the alcohol solvent adhered to the surface of the carbon-based adsorbent is not included in the content of substances contained in the carbon-based adsorbent composition.

[0102] As shown in Figure 1, carbon-based adsorbents are typically porous materials. Carbon-based adsorbents are typically thought to have multiple strong-binding sites where lactic acid is easily immobilized and multiple weak-binding sites where lactic acid is less likely to be immobilized. The strong-binding sites are likely to be formed deep within each of the multiple pores of the carbon-based adsorbent. Immobilized lactic acid bound to the strong-binding sites of the carbon-based adsorbent is unlikely to be released from the carbon-based adsorbent even after an extraction process is performed. In other words, the immobilized lactic acid may be semi-permanently immobilized on the carbon-based adsorbent. On the other hand, lactic acid bound to the weak-binding sites of the carbon-based adsorbent is likely to be released from the carbon-based adsorbent after an extraction process is performed.

[0103] Immobilized lactic acid begins to vaporize at temperatures higher than 120° C. and completely vaporizes at 200° C. Therefore, when a carbon-based adsorbent composition containing immobilized lactic acid is subjected to a drying treatment, the temperature of the drying treatment is is preferably 120°C or less, more preferably 100°C or less, and even more preferably 80°C or less.

[0104] (2) Method for producing lactic acid derivatives The method for producing a lactic acid derivative of the present disclosure includes preparing a lactic acid solution by the method for producing a lactic acid solution of the present disclosure (hereinafter also referred to as a "preparation step"), and synthesizing a lactic acid derivative using the lactic acid solution (hereinafter also referred to as a "synthesis step"). The preparation step and the synthesis step are performed in this order.

[0105] "Lactic acid derivative" refers to a compound derived from lactic acid.

[0106] The method for producing a lactic acid derivative according to the present disclosure has the above-described configuration, and therefore has the same effects as the method for producing a lactic acid solution according to the present disclosure. That is, the method for producing a lactic acid derivative according to the present disclosure can suppress the generation of by-products and produce a lactic acid derivative with a low environmental impact.

[0107] (2.1) Preparation process In the preparation step, a lactic acid solution is prepared by the method for producing a lactic acid solution of the present disclosure. The preparation step is the same as that exemplified as the method for producing a lactic acid solution of the present disclosure. If necessary, the lactic acid solution may be subjected to a concentration treatment, a dehydration treatment, or an addition treatment. In the addition treatment, a solvent (alcohol, water, etc.) or an additive (e.g., a polymerization inhibitor, a catalyst, etc.) may be added to the lactic acid solution.

[0108] (2.2) Synthesis process In the synthesis step, a lactic acid derivative is synthesized using the lactic acid solution.

[0109] (2.2.1) Lactic acid derivatives The lactic acid derivative is not particularly limited, and examples thereof include a compound represented by the following formula (2) (hereinafter also referred to as "lactic acid ester compound (2)"), acrylic acid, acetaldehyde, 2,3-pentanedione, propionic acid, and 1,2-propanediol.

[0110] [ka]

[0111] In formula (2), R is the same as the example of R in formula (1).

[0112] The method for synthesizing the lactic acid derivative is not particularly limited and may be any known method appropriately selected depending on the type of lactic acid derivative and the type of lactic acid solution. For example, a method for synthesizing the lactic acid ester compound (2) may be an esterification reaction in which lactic acid is reacted with an alcohol, as shown in the following reaction formula (3). A catalyst may be used in the esterification reaction. For example, a method for synthesizing acrylic acid may be a dehydration reaction of lactic acid, as shown in the following reaction formula (4). A catalyst may be used in the dehydration reaction.

[0113] [ka]

[0114] [ka]

[0115] (2.3) First embodiment A method for producing a lactic acid solution and a lactic acid derivative according to a first embodiment of the present disclosure (hereinafter also referred to as the "production method according to the first embodiment") will be described with reference to FIG.

[0116] As shown in Figure 2, the production method of the first embodiment includes a lactic acid production step S10, a first separation step S11, an adsorption step S12, a second separation step S13, an extraction step S14, a third separation step S15, a concentration treatment S16, and a synthesis step S17. In principle, the lactic acid production step S10, the first separation step S11, the adsorption step S12, the second separation step S13, the extraction step S14, the third separation step S15, the concentration treatment S16, and the synthesis step S17 are performed in this order. The adsorption step S12 may be performed after the second separation step S13. The extraction step S14 may be performed after the third separation step S15. Steps S10 to S17 included in the production method of the first embodiment are the same as those exemplified as steps in the production method of the lactic acid solution and lactic acid derivative of the first aspect.

[0117] The production method of the first embodiment further includes a concentration treatment S130, as shown in Fig. 2. The concentration treatment S130 is carried out after the second separation step S13, independently of the extraction step S14. The concentration treatment S130 is the same as that exemplified as the concentration treatment in the method for producing a lactic acid solution according to the first embodiment.

[0118] The steps included in the production method of the first embodiment are the same as the steps exemplified in the production method of the lactic acid solution and lactic acid derivative of the first aspect.

[0119] In the first embodiment, the used liquid separated by carrying out the second separation step S13 is concentrated by a concentration treatment S130. The concentrated used liquid is reused as the aqueous lactic acid solution in the adsorption step S12. In the first embodiment, the extracted adsorbent separated by carrying out the third separation step S15 is reused as the carbon-based adsorbent composition for the adsorption step S12. In the first embodiment, the alcohol separated by the concentration treatment S16 is reused as the alcohol in the extraction step S14.

[0120] The manufacturing method of the first embodiment has the above-mentioned configuration, and therefore, the generation of by-products is suppressed and low Lactic acid solutions and lactic acid derivatives can be produced with minimal environmental impact.

[0121] (2.4) Second embodiment A method for producing a lactic acid derivative according to a second embodiment of the present disclosure (hereinafter also referred to as the "production method according to the second embodiment") will be described with reference to FIG.

[0122] 3, the production method of the second embodiment includes a production-adsorption step S20, a fourth separation step S21, an extraction step S22, a fifth separation step S23, a concentration treatment S24, and a synthesis step S25. In principle, the production-adsorption step S20, the fourth separation step S21, the extraction step S22, the fifth separation step S23, the concentration treatment S24, and the synthesis step S25 are performed in this order. The extraction step S22 may be performed after the fifth separation step S23.

[0123] Steps S20 to S25 included in the production method of the second embodiment are the same as those exemplified as steps in the production method of the lactic acid solution and lactic acid derivative of the second aspect.

[0124] 3, the manufacturing method of the second embodiment includes a concentration treatment S210, an adsorption step S211, a sixth separation step S212, an extraction step S213, and a seventh separation step S214. In principle, the concentration treatment S210, the adsorption step S211, the sixth separation step S212, the extraction step S213, and the seventh separation step S214 are performed in this order. The adsorption step S211 may be performed after the sixth separation step S212. The extraction step S213 may be performed after the seventh separation step S214.

[0125] Steps S210 to S214 included in the manufacturing method of the second embodiment are the same as those exemplified as the steps of the manufacturing method of the lactic acid solution and lactic acid derivatives of the first aspect. Specifically, the concentration step S210 is the same as that exemplified as the concentration step of the manufacturing method of the lactic acid solution of the first aspect. The adsorption step S211 is the same as that exemplified as the adsorption step of the manufacturing method of the lactic acid solution of the first aspect. The sixth separation step S212 is the same as that exemplified as the second separation step of the manufacturing method of the lactic acid solution of the first aspect. The extraction step S213 is the same as that exemplified as the extraction step of the manufacturing method of the lactic acid solution of the first aspect. The seventh separation step S214 is the same as that exemplified as the third separation step of the manufacturing method of the lactic acid solution of the first aspect.

[0126] In the second embodiment, the aqueous lactic acid solution separated in the fourth separation step S21 is concentrated by a concentration treatment S210. The concentrated aqueous lactic acid solution is reused as the aqueous lactic acid solution in the adsorption step S211. In the second embodiment, the extracted adsorbent separated by carrying out the fifth separation step S23 is reused as the carbon-based adsorbent composition in the production adsorption step S20. In the second embodiment, the used liquid separated in the sixth separation step S212 is concentrated by a concentration treatment S210. The concentrated used liquid is reused as an aqueous lactic acid solution in the adsorption step S211. In the second embodiment, the extracted adsorbent separated by carrying out the seventh separation step S214 is reused as the carbon-based adsorbent composition in the adsorption step S211. In the second embodiment, the alcohol vaporized by carrying out the concentration treatment S24 is reused as alcohol in the extraction step S22 and the extraction step S213.

[0127] The production method of the second embodiment has the above-mentioned configuration, and therefore can suppress the generation of by-products and produce a lactic acid solution and a lactic acid derivative with a low environmental impact.

[0128] (3) Lactic acid solution manufacturing system The system for producing a lactic acid solution according to the present disclosure includes a container (hereinafter also referred to as a "dual-purpose container") and a carbon-based adsorbent and / or a carbon-based adsorbent composition filled in the container. The configuration allows for the implementation of a first process and a second process. The first process refers to contacting lactic acid produced by lactic acid fermentation with a carbon-based adsorbent and / or a carbon-based adsorbent composition to adsorb the lactic acid onto the carbon-based adsorbent and / or the carbon-based adsorbent composition to obtain a carbon-based adsorbent composition (i.e., the "adsorption step"). The second process refers to contacting the carbon-based adsorbent composition to which the lactic acid has been adsorbed with a solvent containing alcohol to extract the lactic acid into the solvent (i.e., the "extraction step").

[0129] The production system of the present disclosure has the above-described configuration, and thus can suppress the generation of by-products and produce a lactic acid solution with a low environmental impact. In addition, the production system of the present disclosure can perform the adsorption step and the extraction step without moving the carbon-based adsorbent.

[0130] In the production system of the present disclosure, lactic acid can be extracted with a solvent used for synthesizing a lactic acid derivative. Therefore, the lactic acid solution obtained by extracting lactic acid adsorbed on a carbon-based adsorbent composition into an alcohol solvent can be used directly for synthesizing a lactic acid derivative. If necessary, the lactic acid solution may be concentrated before use in synthesizing a lactic acid derivative.

[0131] The production system of the present disclosure is suitable for use in the method for producing a lactic acid solution of the present disclosure.

[0132] (3.1) Dual-purpose container The manufacturing system of the present disclosure includes a dual-purpose container. The dual-purpose container can perform the adsorption process and the extraction process. Specifically, the adsorption process produces a first mixed solution. The second separation process separates the used liquid from the first mixed solution to produce a post-adsorption adsorbent. The extraction process uses the post-adsorption adsorbent to produce a second mixed solution. The third separation process separates the post-extraction adsorbent from the second mixed solution to produce a lactic acid solution.

[0133] The dual-purpose container is not particularly limited as long as it is a container capable of carrying out the adsorption step and the extraction step, and may be a known container. The dual-purpose container may be equipped with a second valved filter. The second valved filter allows the used liquid and the lactic acid solution to pass through, but does not allow the post-adsorption adsorbent or the post-extraction adsorbent to pass through. By equipping the dual-purpose container with the second valved filter, the second separation step, the third separation step, and the removal of contamination can be easily carried out. The second valved filter may have a known configuration. The dual-purpose container may be equipped with a known liquid addition device that adds a lactic acid aqueous solution, an alcohol solvent, etc. to the dual-purpose container. The dual-purpose container may be equipped with a known device (e.g., a heating device, a stirring device, an air suction device, an air blower, a hot air blower, a suction filtration device, etc.).

[0134] (3.2) Carbonaceous Adsorbents and Carbonaceous Adsorbent Compositions The manufacturing system of the present disclosure includes a carbon-based adsorbent and / or a carbon-based adsorbent composition filled in a dual-purpose container.

[0135] Examples of the carbon-based adsorbent and carbon-based adsorbent composition include the same carbon-based adsorbents and carbon-based adsorbent compositions as those exemplified as the carbon-based adsorbents and carbon-based adsorbent compositions in the method for producing a lactic acid solution of the present disclosure.

[0136] The carbonaceous adsorbent composition may contain lactic acid immobilized on a carbonaceous adsorbent (i.e., immobilized lactic acid), and the content of the immobilized lactic acid (i.e., immobilized lactic acid) is preferably 1% by mass to 15% by mass relative to 100% by mass of the carbonaceous adsorbent composition. The content of the immobilized lactic acid is more preferably 3% by mass to 10% by mass. The contents of lactic acid monomer, lactic acid oligomer, and lactate salt contained in the immobilized lactic acid are not particularly limited. The carbon-based adsorbent adsorbs moisture from the atmosphere, but does not affect the adsorption and extraction of lactic acid, and the moisture is easily evaporated by drying. Therefore, the mass of water adsorbed on the carbon-based adsorbent is not included in the content of the substance contained in the carbon-based adsorbent composition. After the extraction process, the surface of the adsorbent after extraction is However, the alcohol solvent adheres to the surface of the carbon-based adsorbent, but the alcohol solvent does not affect the adsorption and extraction of lactic acid and is easily evaporated during the drying process. Therefore, the mass of the alcohol solvent adhered to the surface of the carbon-based adsorbent is not included in the content of the substance contained in the carbon-based adsorbent composition.

[0137] (3.3) Used liquid concentration container The manufacturing system of the present disclosure may further include a used liquid concentrating container. The used liquid concentrating container concentrates the used liquid separated by the first separation step. In other words, the concentration of lactic acid in the used liquid is increased. The concentrated used liquid is introduced into the dual-purpose container as an aqueous lactic acid solution and reused.

[0138] The used liquid concentration container is not particularly limited as long as it is a container capable of concentrating used liquid, and may be any known container. The used liquid concentration container is equipped with a device for concentrating used liquid (e.g., a heating device, a blower, a hot air blower, an air suction device, or an agitator). The used liquid concentration container may also be equipped with a known device (e.g., a liquid delivery device).

[0139] The used liquid concentrating container may or may not be connected to the dual-purpose container via piping.

[0140] (3.4) Lactic acid production vessel The production system of the present disclosure preferably further includes a lactic acid production vessel that produces lactic acid by lactic acid fermentation. A lactic acid production step is carried out in the lactic acid production vessel. By carrying out the lactic acid production step, a microorganism-containing fermentation liquid is obtained. If a neutralizing agent is used in the lactic acid production step, a desalting treatment may be carried out in the vessel.

[0141] The lactic acid production vessel is not particularly limited as long as it is a vessel capable of carrying out the lactic acid production step, and may be a known vessel. The lactic acid production vessel may be equipped with a first valved filter. The first valved filter allows the aqueous lactic acid solution to pass through but does not allow solids to pass through. By providing the lactic acid production vessel with the first valved filter, it is possible to easily remove the solids and contaminations generated in the first separation step and desalting treatment. The first valved filter may have a known configuration. The lactic acid production vessel may be equipped with known devices (for example, a blower, a hot air blower, a suction device, a heating device, or a stirring device).

[0142] The lactic acid production vessel may or may not be connected to the dual-purpose vessel via piping.

[0143] (3.5) Carbon-based adsorbents and carbon-based adsorbent compositions The production system of the present disclosure preferably further comprises a carbon-based adsorbent and / or a carbon-based adsorbent composition packed in the lactic acid production vessel. When the production system of the present disclosure further comprises a carbon-based adsorbent and / or a carbon-based adsorbent composition packed in the lactic acid production vessel, an extraction process may be performed on the post-fermentation adsorbent in the lactic acid production vessel. This makes it possible to increase the amount of lactic acid produced. In addition, it becomes possible to perform the production adsorption process and the extraction process without moving the carbon-based adsorbent composition.

[0144] Examples of the carbon-based adsorbent and carbon-based adsorbent composition include those similar to those exemplified as the carbon-based adsorbent composition in the method for producing a lactic acid solution of the present disclosure.

[0145] The carbon-based adsorbent composition filled in the lactic acid production vessel is a carbon-based adsorbent composition containing a carbon-based adsorbent and lactic acid immobilized on the carbon-based adsorbent (i.e., immobilized lactic acid), and the content of the lactic acid immobilized on the carbon-based adsorbent (i.e., immobilized lactic acid) is preferably 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent. The content is more preferably 3% by mass to 10% by mass. There are no particular limitations on the content of each of the lactic acid monomer, lactic acid oligomer, and lactate salt contained in the immobilized lactic acid. The carbon-based adsorbent adsorbs moisture from the atmosphere, but does not affect the adsorption and extraction of lactic acid and is easily evaporated by drying. Therefore, the mass of water adsorbed on the carbon-based adsorbent is not included in the content of substances contained in the carbon-based adsorbent composition. After the extraction process, an alcohol solvent adheres to the surface of the post-extraction adsorbent, but the alcohol solvent does not affect the adsorption and extraction of lactic acid and is easily evaporated by drying. Therefore, the mass of the alcohol solvent adhered to the surface of the carbon-based adsorbent is not included in the content of substances contained in the carbon-based adsorbent composition.

[0146] (3.6) Lactic acid solution concentration container The production system of the present disclosure may further include a lactic acid solution concentrating container. Concentration is performed in the lactic acid solution concentrating container. If concentration is not performed, the container may be used as a container for storing the lactic acid solution. If the lactic acid solution contains lactate, a desalting treatment may be performed in the container.

[0147] The lactic acid solution concentrating container is not particularly limited as long as it is a container capable of performing concentration, and may be a known container. The lactic acid solution concentrating container may be equipped with a third valve-equipped filter. The third valve-equipped filter allows the lactic acid solution to pass through but does not allow solids to pass through. By providing the lactic acid solution concentrating container with the third valve-equipped filter, it is possible to easily remove solids generated in the desalting process and remove contamination. The third valve-equipped filter may have a known configuration. The lactic acid solution concentrating container is equipped with a device for performing concentration (e.g., a heating device, a blower, a hot air blower, an air suction device, or an agitator). The lactic acid solution concentrating container may be equipped with a known device (e.g., a liquid delivery device).

[0148] The lactic acid solution concentrating vessel may or may not be connected to the dual-purpose vessel via piping. When the lactic acid production vessel is equipped with a carbon-based adsorbent and / or a carbon-based adsorbent composition, the lactic acid solution concentrating vessel may or may not be connected to the lactic acid production vessel via piping.

[0149] (3.7) Alcohol solvent collection container When the production system of the present disclosure includes a lactic acid solution concentrating container, the production system of the present disclosure may further include an alcohol solvent recovery container. The alcohol solvent recovery container recovers the alcohol solvent discharged from the lactic acid solution concentrating container during concentration. The recovered alcohol solvent is introduced into the dual-purpose container as the alcohol solvent and reused in the extraction step.

[0150] The alcohol solvent recovery container is not particularly limited as long as it is a container capable of recovering the alcohol solvent, and may be a known container. The alcohol solvent recovery container may be equipped with a known device (for example, a cooling device, a liquid delivery device, etc.).

[0151] The alcohol solvent recovery vessel may or may not be connected to the lactic acid solution concentration vessel and the dual-purpose vessel by piping. When the lactic acid production vessel is equipped with a carbon-based adsorbent and / or a carbon-based adsorbent composition, the alcohol solvent recovery vessel may or may not be connected to the lactic acid production vessel by piping.

[0152] (3.8) Composite containers The manufacturing system of the present disclosure may include a synthesis vessel in which the synthesis process is carried out.

[0153] The synthesis vessel is not particularly limited as long as it is a vessel capable of carrying out the synthesis step, and any known vessel may be used. The synthesis vessel may be equipped with known devices for carrying out the synthesis step (for example, a dehydration device, a reflux device, a cooling device, an aspiration device, a heating device, or an agitation device).

[0154] When the production system of the present disclosure includes a lactic acid solution concentrating container, the synthesis container may or may not be connected to the lactic acid solution concentrating container via piping. When the production system of the present disclosure does not include a lactic acid solution concentrating container, the synthesis container may or may not be connected to the dual-purpose container via piping. Furthermore, when the lactic acid production container includes a carbon-based adsorbent and / or a carbon-based adsorbent composition, the synthesis container may or may not be connected to the lactic acid production container via piping.

[0155] (3.9) Storage container The production system of the present disclosure may include a storage container. The storage container is used to temporarily store the lactic acid aqueous solution, the used solution, and the lactic acid solution before the next step. The storage container may also be used to store the lactic acid derivative obtained after the synthesis step.

[0156] The manufacturing system of the present disclosure may include multiple lactic acid production vessels, dual-purpose vessels, lactic acid solution concentrating vessels, used liquid concentrating vessels, alcohol recovery vessels, synthesis vessels, and storage vessels.

[0157] (3.10) First embodiment A manufacturing system 1A according to a first embodiment of the present disclosure will be described with reference to FIG.

[0158] As shown in Fig. 4, the production system 1A includes a lactic acid production vessel 10, a dual-purpose vessel 20, a lactic acid solution concentrating vessel 30, a used liquid concentrating vessel 40, an alcohol solvent recovery vessel 50, a synthesis vessel 60, and a directional valve 70. The arrows in Fig. 4 indicate the movement directions of the liquid and gas. The movement directions of the liquid and gas can be changed by the directional valve 70.

[0159] The lactic acid production vessel 10 includes a first valved filter 11. The dual-purpose vessel 20 includes a second valved filter 21 and a carbon-based adsorbent and / or carbon-based adsorbent composition 22. The lactic acid solution concentration vessel includes a third valved filter 31.

[0160] The production system 1A implements the method for producing a lactic acid solution according to the present disclosure.

[0161] The production system 1A has the above-described configuration, and therefore can suppress the generation of by-products and produce a lactic acid solution with a low environmental impact.

[0162] (3.11) Second embodiment A manufacturing system 1B according to a second embodiment of the present disclosure will be described with reference to FIG.

[0163] As shown in Fig. 5, the production system 1B includes a lactic acid production vessel 10, a dual-purpose vessel 20, a lactic acid solution concentrating vessel 30, a used liquid concentrating vessel 40, an alcohol solvent recovery vessel 50, a synthesis vessel 60, a directional valve 70, a directional valve 80, and a directional valve 90. The arrows in Fig. 5 indicate the movement directions of the liquid and gas. The movement directions of the liquid and gas can be changed by the directional valves 70, 80, and 90.

[0164] The lactic acid production vessel 10 includes a first valved filter 11 and a carbon-based adsorbent and / or carbon-based adsorbent composition 12. The dual-purpose vessel 20 includes a second valved filter 21 and a carbon-based adsorbent and / or carbon-based adsorbent composition 22. The lactic acid solution concentration vessel includes a third valved filter 31.

[0165] In the production system 1B, the method for producing a lactic acid solution according to the present disclosure is carried out.

[0166] The production system 1B has the above-described configuration, and therefore can suppress the generation of by-products and produce a lactic acid solution with a low environmental impact.

[0167] (4) Carbon-based adsorbent composition The carbonaceous adsorbent composition of the present disclosure is a carbonaceous adsorbent composition comprising a carbonaceous adsorbent and lactic acid immobilized on the carbonaceous adsorbent, and the content of lactic acid immobilized on the carbonaceous adsorbent (i.e., immobilized lactic acid) is preferably 1% by mass to 15% by mass relative to 100% by mass of the carbonaceous adsorbent composition. The content of immobilized lactic acid is more preferably 3% by mass to 10% by mass. The contents of lactic acid monomer, lactic acid oligomer, and lactate salt contained in the immobilized lactic acid are not particularly limited. The carbon-based adsorbent adsorbs moisture from the atmosphere, but does not affect the adsorption and extraction of lactic acid and is easily evaporated by drying. Therefore, the mass of water adsorbed on the carbon-based adsorbent is not included in the content of substances contained in the carbon-based adsorbent composition. After the extraction process, an alcohol solvent adheres to the surface of the post-extraction adsorbent, but the alcohol solvent does not affect the adsorption and extraction of lactic acid and is easily evaporated by drying. Therefore, the mass of the alcohol solvent adhered to the surface of the carbon-based adsorbent is not included in the content of substances contained in the carbon-based adsorbent composition.

[0168] The carbon-based adsorbent composition of the present disclosure has the above-described configuration, and therefore can suppress the generation of by-products and produce a lactic acid solution with a low environmental impact. In addition, the carbon-based adsorbent composition of the present disclosure can increase the lactic acid extraction rate and significantly reduce the amount of lactic acid waste.

[0169] Examples of the carbon-based adsorbent composition of the present disclosure include those similar to those exemplified as the carbon-based adsorbent composition in the method for producing a lactic acid solution of the present disclosure. [Example]

[0170] The above embodiment will be specifically described below using examples, but the above embodiment is not limited to these examples.

[0171] [1] Preparation of lactic acid solution [1.1] Preparation Example 1 In a 90% by mass lactic acid aqueous solution (fermentation-derived, Fujifilm Wako Pure Chemical Industries, Ltd., Wako Special Grade), approximately 36% by mass of the total lactic acid was lactic acid oligomers. Therefore, the lactic acid oligomers were decomposed into lactic acid monomers. Specifically, a 90% by mass L-lactic acid aqueous solution (fermentation-derived, Fujifilm Wako Pure Chemical Industries, Ltd., Wako Special Grade) was diluted with water to obtain a lactic acid aqueous solution with a lactic acid content of 20% by mass. The lactic acid aqueous solution was then refluxed in an aluminum bath at 95°C for 24 hours to decompose the lactic acid oligomers into lactic acid monomers. This procedure yielded a model lactic acid aqueous solution (208.4 g / L lactic acid aqueous solution). The concentrations of lactic acid monomers and lactic acid oligomers in the model lactic acid aqueous solution were measured by high-performance liquid chromatography (HPLC). The measurement results are shown in Table 1.

[0172] [1.2] Preparation Example 2 Saccharomyces cerevisiae OC2-2T T165 strain (lower (see Non-Patent Document 4) was cultured in a culture medium (glucose: 20 g / L, yeast extract: 10 g / L, peptone: 20 g / L) for 18 hours to prepare a lactic acid-producing yeast solution. The lactic acid-producing yeast solution was added to 100 mL of fermentation medium (glucose 120 g / L, yeast extract 10 g / L, peptone 20 g / L) so that the bacterial concentration was 2% PCV (packed cell volume), and fermentation was carried out under conditions of 32°C, 72 hours, and 80 rpm (lactic acid production step). After fermentation was completed, the microorganism-containing fermentation solution was filtered and centrifuged twice to obtain an aqueous lactic acid solution from which the lactic acid-producing yeast and other components had been removed (first separation step). The concentrations of lactic acid monomer and lactic acid oligomer in the obtained aqueous lactic acid solution were measured by HPLC. The measurement results are shown in Table 1. Non-patent document 4: Saitoh S et al., Appl. Environ. Microbiol., 2005, 71, pp.2789-2792.

[0173] [1.3] Preparation Example 3 The PDC (pyruvate decarboxylase) 5 gene of the T165 strain was disrupted using the method described in Non-Patent Document 5 below. The GPD (glycerol-3-phosphate dehydrogenase) 1 gene of this strain was then disrupted using the method described in Japanese Patent No. 4744115, and further subjected to EMS (ethyl methane sulfonate) mutagenesis. The resulting 1280E06 strain was cultured in a culture medium (glucose: 20 g / L, yeast extract: 10 g / L, peptone: 20 g / L) to prepare a lactic acid-producing yeast solution. The lactic acid-producing yeast solution was added to 100 mL of fermentation medium (glucose: 150 g / L, yeast extract: 10 g / L, peptone: 20 g / L) to a bacterial concentration of 2% PCV (packed cell volume), and fermentation was carried out under conditions of 32°C, 72 hours, and 80 rpm (lactic acid production process). After fermentation was completed, the microorganism-containing fermentation broth was filtered and centrifuged twice to obtain an aqueous lactic acid solution from which lactic acid-producing yeast and other substances had been removed (first separation step). The concentrations of lactic acid monomers and lactic acid oligomers in the resulting aqueous lactic acid solution were measured by HPLC. The measurement results are shown in Table 1. Non-patent document 5: Ishida, N. et al., Biosci. Biotechnol. Biochem. 70, 2006, p.1148-1153

[0174] [1.4] Preparation Example 4 A lactic acid fermentation yeast liquid similar to that in Preparation Example 3 was prepared. The lactic acid-producing yeast liquid was added to a fermentation medium (glucose: 120 g / L, molasses: 0.4 g / L, KH2PO4: 0.4 g / L, Mg2SO4: 0.4 g / L) so that the bacterial concentration was 2% PCV, and fermentation was carried out under conditions of 32°C, 72 hours, and 200 rpm (lactic acid production step). After fermentation was completed, the microorganism-containing fermentation liquid was filtered and centrifuged twice to obtain an aqueous lactic acid solution from which the lactic acid-producing yeast and other components had been removed (first separation step). The concentrations of lactic acid monomer and lactic acid oligomer in the obtained aqueous lactic acid solution were measured by HPLC. The measurement results are shown in Table 1.

[0175] [1.5] Preparation Example 5 The same procedure as in Preparation Example 4 was carried out, except that 4 g / L (0.04 mol / L) of calcium carbonate was added as a neutralizing agent to the fermentation medium (glucose: 120 g / L, molasses: 0.4 g / L, KH2PO4: 0.4 g / L, Mg2SO4: 0.4 g / L).

[0176] [1.6] Preparation Example 6 The same procedure as in Preparation Example 5 was carried out, except that the amount of calcium carbonate used was changed to 10 g / L (0.10 mol / L).

[0177] [1.7] Summary [Table 1]

[0178] A model lactic acid aqueous solution containing almost no lactic acid oligomer was obtained by dilution and heat treatment in Preparation Example 1. The lactic acid concentration of the model lactic acid aqueous solution (the total concentration of the lactic acid monomer and the lactic acid oligomer) was 208.4 g / L. In Preparation Examples 2 and 3, no neutralizing agent was used, but by using a genetically modified yeast, which is a fungus, it was possible to produce aqueous lactic acid solutions with a lactic acid monomer concentration of 50 g / L or more. The aqueous lactic acid solutions in Preparation Examples 2 and 3 did not contain lactic acid oligomers. In Preparation Example 4, the lactic acid fermentation conditions of Preparation Example 3 were revised, and the amount of lactic acid produced increased, enabling the production of an aqueous lactic acid solution with a lactic acid monomer concentration of 71.8 g / L. In Preparation Example 5, in addition to the genetically modified yeast, 4 g / L (0.04 mol / L) of calcium carbonate was added to the fermentation medium as a neutralizing agent, which further increased the amount of lactic acid produced, resulting in the production of a lactic acid aqueous solution with a lactic acid monomer concentration of 79.7 g / L. In Preparation Example 6, when the amount of calcium carbonate used was changed to 10 g / L (0.10 mol / L), the amount of lactic acid produced further increased, and a lactic acid aqueous solution with a lactic acid monomer concentration of 86.4 g / L was produced. Normally, when producing a lactic acid aqueous solution with a lactic acid monomer concentration of 86.4 g / L, 48.0 g / L (0.48 mol / L) of calcium carbonate is required to completely neutralize the lactic acid. Preparation Examples 5 and 6 showed that by using highly acid-resistant fungi, it is possible to increase the amount of lactic acid produced even with a small amount of neutralizing agent.

[0179] [2] Verification using a model lactic acid aqueous solution [2.1] Example 1 3.125 mL of the model lactic acid aqueous solution (208.4 g / L lactic acid aqueous solution) obtained in Preparation Example 1 was diluted with 9.375 mL of water to prepare 12.5 mL of 52.1 g / L lactic acid aqueous solution. Granular activated carbon (shape: cylindrical, diameter: approximately 2 mm to 4 mm, length: approximately 2 mm to 15 mm, total length: approximately 2 mm to 15 mm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was prepared as a carbon-based adsorbent. 5 g of the 52.1 g / L lactic acid aqueous solution was added to the carbon-based adsorbent and allowed to stand at 30°C for 8 hours (the adsorption step was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain the adsorbent after adsorption and the spent liquid (second separation step). The adsorbent after adsorption was dried overnight in an oven at 60°C to remove water. The mass of the adsorbent after adsorption was then measured. The contents of lactic acid monomer and lactic acid oligomer in the obtained spent liquid were measured by HPLC. The lactic acid adsorption capacity was calculated from the amount of lactic acid remaining in the spent liquid. The lactic acid adsorption capacity was also calculated using the following formula (a1). The value calculated using the following formula (a1) was compared with the lactic acid adsorption capacity calculated by HPLC, and the lower value was adopted as the lactic acid adsorption capacity.

[0180] Equation (a1): Lactic acid adsorption amount [g] = mass of adsorbent after adsorption after drying [g] - implementation of adsorption process Mass of previous carbon-based adsorbent [g]

[0181] 15 mL of ethyl alcohol (fermentation-derived) was added to the adsorbent after adsorption, and the mixture was allowed to stand at 30°C for 8 hours (the extraction step was carried out at 30°C to maintain a constant test environment). This was then filtered to obtain a lactic acid solution and an extracted adsorbent (third separation step). The extracted adsorbent was air-dried overnight, and then 15 mL of ethyl alcohol (fermentation-derived) was added again, and the mixture was allowed to stand at 30°C for 8 hours (the extraction step was carried out at 30°C to maintain a constant test environment). This was then filtered to obtain a lactic acid solution and an extracted adsorbent (third separation step). That is, in Example 1, the extraction step and the third separation step were carried out in this order twice in total. The contents of lactic acid monomer and lactic acid oligomer in the obtained lactic acid solution were measured by HPLC to determine the amount of lactic acid extracted. The lactic acid extraction rate was calculated using the following formula (a2). The results are shown in Table 2.

[0182] Formula (a2): Lactic acid extraction rate [%] = 100 × (lactic acid extraction amount [g] / lactic acid adsorption amount [g])

[0183] [2.2] Example 2 The same procedure as in Example 1 was repeated, except that 6.25 mL of the model lactic acid aqueous solution (208.4 g / L lactic acid aqueous solution) obtained in Preparation Example 1 was diluted with 6.25 mL of water to prepare 12.5 mL of a 104.2 g / L lactic acid aqueous solution. The results are shown in Table 2.

[0184] [2.3] Example 3 The same procedure as in Example 1 was carried out, except that 12.5 mL of the model lactic acid aqueous solution (208.4 g / L lactic acid aqueous solution) obtained in Preparation Example 1 was used as is. The results are shown in Table 2.

[0185] [2.4] Comparative Example 1 Instead of granular activated carbon, molecular sieves 13X (Na-X type zeolite, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to the model lactic acid aqueous solution. However, the model lactic acid aqueous solution gelled. Therefore, it was difficult to measure the amount of lactic acid adsorbed and to perform the lactic acid extraction procedure.

[0186] [2.5] Summary [Table 2]

[0187] Examples 1 to 3 demonstrate that it is possible to adsorb lactic acid onto a carbon-based adsorbent and then extract lactic acid from the adsorbent after adsorption with ethyl alcohol. There was a tendency for the lactic acid extraction rate to increase as the amount of lactic acid adsorbed increased. In Comparative Example 1, the aqueous lactic acid solution gelled, making it impossible to measure the amount of adsorbed lactic acid and perform the lactic acid extraction procedure.

[0188] [3] Examples 2-2, 2-3, 2-4, and 2-5 The repeated use of the post-extraction adsorbent (carbon-based adsorbent composition after the extraction process) was investigated. Example 2 was designated as the first run, and Example 2-N was designated as the Nth run. Example 2-N was carried out according to the following procedure. N is an integer between 2 and 5. The post-extraction adsorbent ((N-1)th run) was air-dried overnight, and then 12.5 mL of a 104.2 g / L lactic acid aqueous solution prepared using the same procedure as in Example 2 was added to the post-extraction adsorbent ((N-1)th run) and allowed to stand at 30°C for 8 hours (the adsorption process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain the post-adsorption adsorbent ((Nth run)) and a used liquid (second separation process). The post-adsorption adsorbent was dried overnight in an oven at 60°C to remove water. The mass of the post-adsorption adsorbent was then measured. The contents of lactic acid monomer and lactic acid oligomer in the obtained used liquid were measured by HPLC, and the lactic acid adsorption amount was calculated from the amount of lactic acid remaining in the used liquid. The lactic acid adsorption amount was also calculated from the following formula (a3): The calculated value of the lactic acid adsorption amount was compared with the lactic acid adsorption amount determined by HPLC, and the lower value was used as the lactic acid adsorption amount (Nth time).

[0189] Equation (a3): Amount of lactic acid adsorbed (Nth time) [g] = Mass of adsorbent after drying (Nth time) [g] - Mass of carbon-based adsorbent before the first adsorption step [g] - Amount of immobilized lactic acid contained in adsorbent after extraction ((N-1)th time) [g]

[0190] 15 mL of ethyl alcohol (fermentation-derived) was added to the adsorbent after adsorption (Nth time), and the mixture was left to stand at 30°C for 8 hours (the extraction process was carried out at 30°C to maintain a constant test environment). This was then filtered to obtain a lactic acid solution and an adsorbent after extraction (third separation process). The adsorbent after extraction was air-dried overnight, and then 15 mL of ethyl alcohol (fermentation-derived) was added again, and the mixture was left to stand at 30°C for 8 hours (the extraction process was carried out at 30°C to maintain a constant test environment). This was then filtered to obtain a lactic acid solution and an adsorbent after extraction (Nth time) (third separation process). The contents of lactic acid monomer and lactic acid oligomer in the resulting lactic acid solution were measured by HPLC to determine the amount of lactic acid extracted (Nth time). The lactic acid extraction rate was calculated using the following formula (a4):

[0191] Formula (a4): Lactic acid extraction rate (Nth time) [%] = 100 × lactic acid extraction amount (Nth time) [g] / lactic acid adsorption amount (Nth time) [g]

[0192] The amount of immobilized lactic acid contained in the adsorbent after extraction (first time) was calculated using the following formula (a5): The content of immobilized lactic acid (first time) relative to 100% by mass of the carbon-based adsorbent was calculated using the following formula (a6):

[0193] Equation (a5): Amount of immobilized lactic acid contained in the adsorbent after extraction (1st time) [g] = Amount of lactic acid adsorbed (1st time) [g] - Amount of lactic acid extracted (1st time) [g] Formula (a6): Content of immobilized lactic acid relative to 100% by mass of carbon-based adsorbent (first time) [mass%] = 100 × amount of immobilized lactic acid contained in adsorbent after extraction (first time) [g] / mass of carbon-based adsorbent before the first adsorption step [g]

[0194] The amount of immobilized lactic acid contained in the adsorbent after extraction (Nth time) was calculated using the following formula (a7): The content of immobilized lactic acid (Nth time) relative to 100% by mass of the carbon-based adsorbent was calculated using the following formula (a8):

[0195] Equation (a7): Amount of immobilized lactic acid contained in the adsorbent after extraction (Nth time) [g] = Amount of immobilized lactic acid contained in the adsorbent after extraction ((N-1)th time) [g] + Amount of adsorbed lactic acid (Nth time) [g] - Amount of extracted lactic acid (Nth time) [g] Formula (a8): Content of immobilized lactic acid relative to 100% by mass of carbon-based adsorbent [mass%] = 100 × amount of immobilized lactic acid contained in adsorbent after extraction (Nth time) [g] / mass of carbon-based adsorbent before the first adsorption step [g]

[0196] To reproduce the condition of a multi-purpose container, the same container was used without cleaning in the adsorption and extraction steps of Examples 2 to 2-5. In the second and third separation steps, the same filters and accessories were used for filtration without cleaning or replacing.

[0197] [3.1] Summary [Table 3]

[0198] Examples 2, 2-2, and 2-3 showed a tendency for the lactic acid extraction rate to increase with increasing use up to the third use of the carbon-based adsorbent (the second use of the carbon-based adsorbent composition). The lactic acid extraction rate after the third use exceeded 100% (Figure 6). This is thought to be because lactic acid that could not be extracted in the second extraction was also extracted in the third extraction. The reason for the higher lactic acid extraction rate after the second and third uses of the carbon-based adsorbent is not entirely clear, but is speculated as follows. In the first lactic acid adsorption and extraction, lactic acid adsorbed to the strong binding sites of the carbon-based adsorbent was not completely extracted and remained as immobilized lactic acid. In the second and subsequent lactic acid adsorption and extraction, lactic acid adsorption and extraction were repeated mainly at the weak binding sites of the carbon-based adsorbent, which are more likely to extract lactic acid (see Figure 1). This is thought to be the reason for the higher lactic acid extraction rate. Examples 2-4 and 2-5 showed that the lactic acid extraction rate remained close to 100% even after the fourth use. Therefore, it is believed that lactic acid is immobilized on most of the strong binding sites of the carbon-based adsorbent. Therefore, it is believed that the same lactic acid adsorption amount and lactic acid extraction rate can be maintained even after the sixth use, and the carbon-based adsorbent composition can be used repeatedly semi-permanently. On the other hand, the amount of lactic acid that can be adsorbed at one time decreases depending on the amount of immobilized lactic acid. However, it is possible to concentrate the used liquid containing lactic acid that was not completely adsorbed by the carbon-based adsorbent and adsorb it again on the carbon-based adsorbent and / or carbon-based adsorbent composition (S13 → S130 → S12 in Figure 2). Therefore, the loss of lactic acid is minimized.

[0199] [4.1] Reference example 1 To investigate the mass loss of the adsorbent after adsorption when it was heated to 200°C, a differential thermobalance (Rigaku Holdings Corporation's ThermoPlusEV02) was used. An aluminum pan containing the adsorbent after adsorption (approximately 10 mg to 20 mg) obtained in Example 2 was placed on the differential thermobalance. The adsorbent after adsorption was then heated in air to 200°C (heating rate: 10°C / min). The mass loss rate (TG [%]) of the adsorbent after adsorption versus heating temperature was measured. The results are shown in Figure 7.

[0200] [4.2] Reference Example 2 (Blank measurement) The same procedure as in Reference Example 1 was carried out, except that unused granular activated carbon (carbon-based adsorbent, shape: cylindrical, diameter: approximately 2 mm to 4 mm, length: approximately 2 mm to 15 mm, total length: approximately 2 mm to 15 mm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of the post-adsorption adsorbent. Lactic acid was not adsorbed onto the granular activated carbon.

[0201] 7, the mass loss rates of Reference Examples 1 and 2 were almost the same up to around 100° C., and the mass loss rate at 100° C. was approximately 1.0%. Because carbon-based adsorbents adsorb water in the air, the mass loss up to around 100° C. is presumed to be due to the evaporation of water. In Reference Example 2, almost no mass loss occurred after 100° C. In Reference Example 1, a further mass loss occurred around 120° C. From the above, it is presumed that lactic acid begins to vaporize around 120° C.

[0202] [4.3] Comparative Example 2 The same procedure as in Example 2 was followed, except that the extraction solvent was changed from ethyl alcohol to acetone. Patent Document 5 discloses that activated carbon is heated and dried at 200°C for 1 hour before reuse. The amount of lactic acid immobilized on the carbon-based adsorbent that evaporates as a result of this heating and drying was investigated. To measure the amount of lactic acid vaporization, the extracted adsorbent, from which acetone had been removed by air drying, and a differential thermobalance (Rigaku Holdings Corporation's "ThermoPlusEV02") were used. An aluminum pan containing the extracted adsorbent (approximately 10 mg to 20 mg) was placed on the differential thermobalance. The extracted adsorbent was heated in air at 200°C for 1 hour (heating at 10°C / min). The mass loss rate (TG [%]) of the extracted adsorbent over heating time was measured. The results are shown in Figure 8. For the post-extraction adsorbent after heat drying, the amount of lactic acid remaining relative to 100% by mass of the carbon-based adsorbent was calculated using the following formula (a9). Note that since the post-extraction adsorbent may contain water, the mass at the time when it reached 120°C was used as the mass of the post-extraction adsorbent (the total mass of the immobilized lactic acid and the carbon-based adsorbent). The calculation results are shown in Table 4.

[0203] Equation (a9): Residual amount of lactic acid relative to 100% by mass of carbon-based adsorbent [mass%] = Content of immobilized lactic acid [mass%] - 100 × (mass [g] at 120°C - mass after heat drying [g]) / mass [g] at 120°C If the residual amount of lactic acid after heat drying is less than 0, the residual amount of lactic acid is considered to be 0.

[0204] [4.4] Summary [Table 4]

[0205] From Comparative Example 2, it was found that all of the immobilized lactic acid was vaporized and disappeared after heating at 200°C for 1 hour. Therefore, in the method of Patent Document 5, the lactic acid that was not completely extracted is discarded every time the activated carbon is used repeatedly. From Figure 8, it is estimated that the immobilized lactic acid also begins to vaporize around 120°C.

[0206] [5] Examples 4 to 6 [5.1] Example 4 0.34 mL of 40% by mass ammonium lactate aqueous solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 6.45 mL of water were added to 5.71 mL of the model lactic acid aqueous solution (208.4 g / L lactic acid aqueous solution) obtained in Preparation Example 1 to prepare 12.5 mL of a mixed aqueous solution of lactic acid monomer and lactate. Specifically, assuming the addition of 0.10 mol / L of ammonia, the lactic acid concentration was adjusted to 104.2 g / L when the lactate salt was converted back to lactic acid monomer. The subsequent lactic acid adsorption and lactic acid extraction operations were performed in the same manner as in Example 1.

[0207] [5.2] Example 5 Two 12.5 mL aliquots of 52.1 g / L lactic acid aqueous solution were prepared by diluting 3.125 mL of the model lactic acid aqueous solution (208.4 g / L lactic acid aqueous solution) obtained in Preparation Example 1 with 9.375 mL of water. Granular activated carbon (shape: cylindrical, diameter: approximately 2 mm to 4 mm, length: approximately 2 to 15 mm, total length: approximately 2 mm to 15 mm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the carbon-based adsorbent. The first 12.5 mL of 52.1 g / L lactic acid aqueous solution was added to 5 g of the carbon-based adsorbent and allowed to stand at 30 °C for 8 hours (the adsorption step was carried out at 30 °C to maintain a constant test environment). The mixture was then filtered to obtain the adsorbent and spent solution (second separation step). The resulting adsorbent was added to a second 12.5 mL of 52.1 g / L lactic acid aqueous solution and allowed to stand at 30°C for 8 hours (the adsorption process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain the adsorbent and spent liquid (second separation process). In other words, in Example 5, the adsorption process and the second separation process were carried out in this order twice in total. The subsequent lactic acid extraction process was carried out in the same manner as in Example 1.

[0208] [5.3] Example 6 The same procedure as in Example 2 was carried out, except that the extraction solvent was changed from ethyl alcohol to isopropanol.

[0209] [5.4] Summary [Table 5]

[0210] The amount of lactic acid adsorbed in Example 4 was equivalent to that of Example 2. The amount of lactic acid extracted in Example 4 was equivalent to that of Example 2. Therefore, it was found that even a mixture of lactic acid monomer and lactate can be adsorbed to a carbon-based adsorbent and extracted with alcohol. The amount of lactic acid adsorption in Example 5 was greater than that in Example 1, which was soaked once in a lactic acid aqueous solution of the same concentration. The amount of lactic acid extracted in Example 5 was greater than that in Example 1. Therefore, by soaking the carbon-based adsorbent twice in a lactic acid aqueous solution, the amount of lactic acid adsorption and the amount of lactic acid extracted were increased. It was found that it was possible to increase The amount of lactic acid adsorbed in Example 6 was equivalent to that of Example 2. The amount of lactic acid extracted in Example 6 was equivalent to that of Example 2. Therefore, lactic acid extraction is possible with alcohol other than ethyl alcohol.

[0211] [6] Verification of lactic acid fermented with genetically modified yeast [6.1] Example 7 As a carbon-based adsorbent, powdered activated carbon (particle size ≦325 mesh, Strem Chem A lactic acid adsorbent (manufactured by Icals, Inc.) was prepared. 100 mL of the lactic acid aqueous solution obtained in Preparation Example 2 was added to 40 g of carbon-based adsorbent, and the mixture was allowed to stand at 30°C for 8 hours (the adsorption process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain the post-adsorption adsorbent and spent liquid (second separation process). The contents of lactic acid monomer and lactic acid oligomer in the spent liquid were measured by HPLC, and the amount of lactic acid adsorption was calculated from the amount of lactic acid remaining in the spent liquid.

[0212] One-eighth of the mass of the adsorbent was collected (5 g of the carbon-based adsorbent alone). 10 mL of ethanol (fermentation-derived) was added to the collected adsorbent and allowed to stand at 30°C for 8 hours (the extraction process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain a lactic acid solution and an extracted adsorbent. The extracted adsorbent was air-dried overnight, and then another 10 mL of ethanol (fermentation-derived) was added and allowed to stand at 30°C for 8 hours (the extraction process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain a lactic acid solution and an extracted adsorbent (third separation process). The contents of lactic acid monomer and lactic acid oligomer in the resulting lactic acid solution were measured by HPLC to determine the amount of lactic acid extracted. The lactic acid extraction rate was calculated using equation (a2).

[0213] [6.2] Example 8 Granular activated carbon (shape: cylindrical, diameter: approximately 2 mm to 4 mm, length: approximately 2 mm to 15 mm, total length: approximately 2 mm to 15 mm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was prepared as a carbon-based adsorbent. 100 mL of the lactic acid aqueous solution obtained in Preparation Example 3 was added to 40 g of the carbon-based adsorbent composition and allowed to stand at 30°C for 8 hours (the adsorption step was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain the post-adsorption adsorbent and spent liquid (second separation step). The contents of lactic acid monomer and lactic acid oligomer in the resulting spent liquid were measured by HPLC, and the amount of lactic acid adsorption was calculated from the amount of lactic acid remaining in the spent liquid.

[0214] The resulting adsorbent was dried overnight in an oven at 60°C. One-eighth of the mass of the dried adsorbent (5 g of carbon-based adsorbent alone) was then collected from the dried adsorbent. 15 mL of ethanol (fermentation-derived) was added to the collected adsorbent and allowed to stand at 30°C for 8 hours (the extraction process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain a lactic acid solution and an extracted adsorbent (second separation process). The extracted adsorbent was air-dried overnight, and then another 15 mL of ethanol (fermentation-derived) was added and allowed to stand at 30°C for 8 hours (the extraction process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain a lactic acid solution and an extracted adsorbent (third separation process). The contents of lactic acid monomer and lactic acid oligomer in the resulting lactic acid solution were measured by HPLC to determine the amount of lactic acid extracted. The lactic acid extraction rate was calculated using equation (a2).

[0215] [6.3] Example 9 0.04 mol / L of sulfuric acid was added to the lactic acid aqueous solution obtained in Preparation Example 5 to neutralize the lactate salt. Granular activated carbon (shape: cylindrical, diameter: approximately 2 mm to 4 mm, length: approximately 2 mm to 15 mm, total length: approximately 2 mm to 15 mm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was prepared as a carbon-based adsorbent. 12.5 mL of the supernatant of the fermentation broth after neutralization was added to 5 g of the carbon-based adsorbent and allowed to stand at 30°C for 8 hours (the adsorption process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain the adsorbent and spent liquid (second separation step). The contents of lactic acid monomer and lactic acid oligomer in the spent liquid were measured by HPLC, and the amount of lactic acid adsorption was calculated from the amount of lactic acid remaining in the spent liquid.

[0216] The resulting adsorbent was dried overnight in an oven at 60°C. Then, 15 mL of ethanol (fermentation-derived) was added to the dried adsorbent and allowed to stand at 30°C for 8 hours (the extraction process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain a lactic acid solution and an extracted adsorbent (third separation process). The extracted adsorbent was air-dried overnight, and then another 15 mL of ethanol (fermentation-derived) was added, and the mixture was allowed to stand at 30°C for 8 hours (the extraction process was carried out at 30°C to maintain a constant test environment). The mixture was then filtered to obtain a lactic acid solution and an extracted adsorbent (third separation process). The contents of lactic acid monomer and lactic acid oligomer in the resulting lactic acid solution were measured by HPLC to determine the amount of lactic acid extracted. The lactic acid extraction rate was calculated using equation (a2).

[0217] [6.4] Example 10 The same procedure as in Example 9 was repeated, except that 0.10 mol / L of sulfuric acid was added to the fermentation liquid obtained in Preparation Example 6 to neutralize the lactate salt.

[0218] [6.5] Summary [Table 6]

[0219] Examples 7 to 10 show that lactic acid produced by fermentation of recombinant yeast can also be adsorbed and extracted in the same manner as model lactic acid.

[0220] [7] Lactic acid fermentation and extraction in the presence of carbon-based adsorbents [7.1] Example 11 A lactic acid fermentation yeast solution similar to that in Preparation Example 3 was prepared. Granular activated carbon (shape: cylindrical, diameter: approximately 2 mm to 4 mm, length: approximately 2 mm to 15 mm, total length: approximately 2 mm to 15 mm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was prepared as the carbon-based adsorbent. 50 mL of fermentation medium (glucose: 120 g / L, molasses: 0.4 g / L, KH2PO4: 0.4 g / L, Mg2SO4: 0.4 g / L) was prepared as the medium. 15 g (300 g / L) of carbon-based adsorbent was added to the fermentation medium, and lactic acid-producing yeast was added to a bacterial concentration of 2% PCV. Subsequently, lactic acid fermentation and lactic acid adsorption were simultaneously carried out under conditions of 32°C, 72 hours, and 200 rpm (production and adsorption step). The resulting microorganism-containing fermentation solution was separated into the post-fermentation adsorbent and an aqueous lactic acid solution by filtration. The contents of lactic acid monomer and lactic acid oligomer in the resulting aqueous lactic acid solution were measured by HPLC.

[0221] To the obtained post-fermentation adsorbent, 45 mL of ethyl alcohol (derived from fermentation) was added. It was left to stand at 30°C for 8 hours (the extraction process and test were carried out at 30°C to keep the test environment constant). After that, it was filtered through a filter to obtain a lactic acid solution and post-extraction adsorbent (fifth separation process). After air-drying the post-extraction adsorbent overnight, 45 mL of ethyl alcohol (derived from fermentation) was added again and it was left to stand at 30°C for 8 hours (the extraction process and test (The experiment was carried out at 30°C to keep the experimental environment constant.) The mixture was then filtered to obtain a lactic acid solution and post-extraction adsorbent (fifth separation step). The contents of lactic acid monomer and lactic acid oligomer in the obtained lactic acid solution were measured by HPLC to determine the amount of lactic acid extracted.

[0222] During the extraction process, the lactic acid-producing yeast attached to the adsorbent after fermentation is released into the ethyl alcohol and deposited on the filter during filtration. Because a granular carbon-based adsorbent composition is used, it is easy to remove the carbon-based adsorbent composition from the filter. The resulting post-extraction adsorbent was heated and dried at 100°C to remove moisture, and then dried at 200°C to calculate the amount of immobilized lactic acid contained in the post-extraction adsorbent from the mass loss.

[0223] The amount of lactic acid produced was calculated using the following formula (a10): The lactic acid concentration was calculated using the following formula (a11):

[0224] Equation (a10): Lactic acid production [g] = amount of lactic acid in lactic acid solution [g] + amount of lactic acid extracted [g] + amount of immobilized lactic acid [g] Equation (a11): Lactic acid concentration [g / L] = Lactic acid production [g] / 0.05 [L]

[0225] The amount of lactic acid adsorbed on the carbon-based adsorbent at the end of fermentation was calculated using the following formula (a12): The lactic acid extraction rate was calculated using the following formula (a13):

[0226] Equation (a12): Amount of lactic acid adsorbed to the adsorbent after fermentation at the end of fermentation [g] = Amount of lactic acid extracted [g] + Amount of immobilized lactic acid [g] Formula (a13): Lactic acid extraction rate [%] = 100 × lactic acid extracted [g] / amount of lactic acid adsorbed to the adsorbent after fermentation at the end of fermentation [g]

[0227] [7.2] Summary [Table 7]

[0228] [Table 8]

[0229] In Example 11, the lactic acid production amount was the sum of the amount of lactic acid in the lactic acid aqueous solution, the amount of lactic acid extracted, and the amount of lactic acid immobilized in the adsorbent after extraction. When the amount of lactic acid production was converted to a lactic acid concentration, the lactic acid concentration in Example 11 was 100.4 g / L. In Preparation Example 4, the concentration of lactic acid obtained was 71.8 g / L. Therefore, even without using a neutralizing agent, the addition of a carbon-based adsorbent increased the amount of lactic acid production. This is thought to be because the lactic acid produced during lactic acid fermentation was adsorbed by the carbon-based adsorbent composition, thereby suppressing a decrease in the pH of the fermentation broth. The results of Example 11 demonstrated that lactic acid can be extracted from the adsorbent after fermentation using ethyl alcohol. Furthermore, lactic acid contained in the lactic acid aqueous solution that was not adsorbed by the adsorbent after fermentation during lactic acid fermentation can be recovered by adsorbing it with a carbon-based adsorbent and / or a carbon-based adsorbent composition and extracting it with alcohol.

[0230] From the above results, it is believed that it is possible to realize a method for producing lactic acid and a method for producing a lactic acid derivative according to the flow diagrams shown in Figures 2 and 3. It is also believed that it is possible to realize the lactic acid production system shown in Figures 4 and 5.

[0231] [8] Comparison of the amount of by-products generated and the number of heating processes Assuming a case where lactic acid fermentation was carried out with 1 L, a comparison was made regarding the amount of by-products generated and the number of heating steps.

[0232] [8.1] Example 12 Using Preparation Example 2 and Example 7 as references, we assumed that 57.1 g / L of lactic acid was obtained by fermentation using recombinant yeast, and then the lactic acid was adsorbed onto a carbon-based adsorbent and extracted with ethyl alcohol. We assumed that the resulting lactic acid-containing alcohol solution was concentrated to 25% by mass. The amount of by-products generated and the heating process were shown in Table 9.

[0233] 8.2 Example 13 With reference to Preparation Example 5 and Example 9, we assumed a case in which 4 g / L (0.04 mol / L) of calcium carbonate was added as a neutralizing agent, 79.7 g / L of lactic acid was obtained by fermentation using genetically modified yeast, and the lactic acid was then adsorbed onto a carbon-based adsorbent and extracted with ethyl alcohol. The resulting lactic acid-containing alcohol solution was concentrated to 25% by mass. The amount of by-products generated and the heating process are shown in the table below. The amount of by-products generated was calculated assuming that all 4 g / L (0.04 mol / L) of calcium carbonate reacted with lactic acid and all of the calcium lactate produced was neutralized with sulfuric acid. The calculation results are shown in Table 9.

[0234] 8.3 Example 14 With reference to Preparation Example 6 and Example 10, the same case as in Example 13 was assumed, except that the amount of calcium carbonate used was 10 g / L (0.10 mol / L) and 86.4 g / L of lactic acid was obtained by fermentation using recombinant yeast. The amount of by-products generated and the heating process are shown in Table 9.

[0235] 8.4 Example 15 Using the lactic acid solution obtained in Example 12, a case was assumed in which esterification was carried out at 90°C using a solid acid catalyst (Amberlyst 15, manufactured by Organo Corporation) in an esterification apparatus equipped with a zeolite water separation membrane, with reference to Non-Patent Document 6 listed below. The amounts of by-products generated and the heating steps are shown in Table 9. Non-patent document 6: Tanaka, K., et al., “Application of Zeolite T membrane to vapor -permentation-aided esterification of lactic acid with ethanol”, Chemical Engineering Science, Vol.57, No.9(2002), p.1577-1584.

[0236] [8.5] ​​Comparative Example 3 The following cases were assumed with reference to Non-Patent Document 2. The amount of by-products generated and the heating process are shown. 9. "Calcium carbonate (55.0 g / L, 0.55 mol / L) was added as a neutralizing agent, and lactic acid (83.5 g / L) neutralized with calcium was obtained through fermentation with Lactobacillus delbrueckii IFO3202. Then, an equal mole of sulfuric acid was added to the calcium to separate it into lactic acid monomer and calcium sulfate, which were then concentrated to 90% by mass." The amount of by-products generated was calculated assuming that all 55.0 g / L (0.55 mol / L) of calcium carbonate reacted with lactic acid and all of the calcium lactate produced was neutralized with sulfuric acid. The calculation results are shown in Table 9.

[0237] [8.6] Comparative Example 4 The following cases were assumed with reference to Patent Document 2. Table 9 shows the amounts of by-products generated and the heating steps. "Ammonia was added as a neutralizer, and fermentation with Lactobacillus casei subsp. Rhamnosus IFO 3863 produced 114.39 g / L. After obtaining ammonium lactate (96.2 g / L as lactic acid), the aqueous ammonium lactate solution was boiled at 100°C and concentrated to 62.0% by mass. Butyl alcohol was added to the concentrated solution in an amount 2.5 times the moles of lactic acid, and the solution was desalted and dehydrated while heated at 150-160°C in an apparatus equipped with reflux and ammonia separation functions. Concentrated sulfuric acid and the evaporated amount of butyl alcohol were added to completely desalt the remaining ammonium lactate. The resulting solution of butyl lactate and butyl alcohol was distilled under reduced pressure at 120°C to separate the butyl lactate and butyl alcohol. Water and a solid acid catalyst (Amberlite 200C, Organo Corporation) were added to the resulting butyl lactate, and the solution was hydrolyzed to lactic acid and desalted while heated at 95-110°C in an apparatus equipped with reflux and butyl alcohol separation functions. The resulting aqueous lactic acid solution was concentrated to 90% by mass.

[0238] [8.7] Comparative Example 5 The following cases were assumed with reference to Patent Document 5. Table 9 shows the amounts of by-products generated and the heating steps. "After obtaining 50 g / L of lactic acid through fermentation using genetically modified yeast, the lactic acid was adsorbed onto activated carbon, extracted with acetone, and concentrated to 90% by mass. To completely remove the acetone, ethyl alcohol was added, and the mixture was concentrated again to 90% by mass, followed by azeotropic removal."

[0239] [8.8] Summary [Table 9]

[0240] No by-products were generated in Example 12. The amount of by-products generated in Example 13 was 5.4 g (6.8% by mass relative to lactic acid). The amount of by-products generated in Example 14 was 13.5 g (15.6% by mass relative to lactic acid). That is, the amounts of by-products generated in each of Examples 13 and 14 were small. Comparative Example 3 is a neutralization fermentation process using the most common calcium carbonate. In Comparative Example 3, the amount of by-products generated was extremely large at 63.1 g (75.6% by mass relative to lactic acid). In Examples 12 to 14, the solvent was ethyl alcohol with a boiling point of 78°C. Therefore, concentration was possible at a lower temperature than in Comparative Example 3, in which the solvent was water (boiling point 100°C), and the concentration was also lower. Note that, in order to reduce the water content in the lactic acid solution, the adsorbent may be dried at 100°C or less after adsorption before lactic acid extraction, but this is not essential.

[0241] Comparative Example 4 is a process in which neutralization and fermentation with ammonia, which is the second most common process after the neutralization and fermentation process using calcium carbonate, is followed by desalination by esterification with butyl alcohol. Comparative Example 4 does not produce by-products, but is thought to consume a lot of energy because it involves multiple heating steps at 100°C or higher. To obtain butyl lactate, it is sufficient to carry out the esterification of ammonium lactate. The esterification method of Comparative Example 3 requires heating the solvent to 120°C or higher. To obtain lactic acid esters (methyl lactate, ethyl lactate, isopropyl lactate, etc.) by reacting alcohol with a boiling point of 100°C or lower with lactic acid, the temperature cannot be raised above the boiling point. Therefore, esterification cannot proceed sufficiently. Furthermore, to reuse the released ammonia, cooling and recovery are required. This further increases energy consumption.

[0242] In Example 15, according to Non-Patent Document 6, esterification is possible at temperatures of 100°C or less. Therefore, even alcohols with boiling points of 100°C or less can be reacted with lactic acid to obtain lactate esters. It is possible to achieve this, and it is estimated that the energy consumption is lower than in Comparative Example 4. In the esterification reaction, the presence of water in the solution may reduce the reaction efficiency. On the other hand, when an esterification apparatus equipped with a water separation membrane is used, even if water is present in the solution, the water is discharged outside the system during the reaction, so there is no problem even if the lactic acid solution contains water.

[0243] In Comparative Example 5, the solvent is acetone (boiling point 56°C), so concentration can be performed at a low temperature, but it is necessary to concentrate to 90%. Furthermore, in order to completely remove the acetone, ethyl alcohol is added and the acetone is removed azeotropically, so more energy is required for concentration than in Examples 12 to 14.

[0244] [7] Summary From these results, it was found that the present disclosure provides "a method for producing a lactic acid solution, a system for producing a lactic acid solution, a method for producing a lactic acid derivative, and a carbon-based adsorbent composition that can suppress the generation of by-products and produce a lactic acid solution and a lactic acid derivative with a low environmental impact."

[0245] Incorporation by reference of related applications This application claims priority from Japanese Patent Application No. 2024-045750, filed March 21, 2024, which is incorporated herein by reference.

Claims

1. contacting lactic acid produced by lactic acid fermentation with a carbon-based adsorbent and / or a carbon-based adsorbent composition to obtain a post-adsorption adsorbent in which the lactic acid is adsorbed onto the carbon-based adsorbent and / or the carbon-based adsorbent composition; contacting the adsorbent with a solvent containing alcohol to extract the lactic acid into the solvent; A method for producing a lactic acid solution, comprising:

2. The method for producing a lactic acid solution according to claim 1 , wherein the post-extraction adsorbent after the extraction step is repeatedly used for the adsorption and the extraction steps.

3. the carbon-based adsorbent composition and the post-extraction adsorbent comprise the carbon-based adsorbent and the lactic acid immobilized on the carbon-based adsorbent; 3. The method for producing a lactic acid solution according to claim 2, wherein the content of the lactic acid immobilized on the carbon-based adsorbent is 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent.

4. The method further comprises not drying the extracted adsorbent after the extraction step before reuse in the adsorption step, or drying the extracted adsorbent; The method for producing a lactic acid solution according to claim 3, wherein the temperature of the drying treatment is 120°C or less.

5. The method for producing a lactic acid solution according to claim 4, wherein the boiling point of the alcohol at atmospheric pressure is 100°C or lower.

6. Further comprising producing the lactic acid by lactic acid fermentation; The method for producing a lactic acid solution according to claim 5 , wherein fungi are used for the lactic acid fermentation.

7. The method for producing a lactic acid solution according to claim 6, wherein the amount of the neutralizing agent used in the lactic acid fermentation is 0.20 mol / L or less.

8. The method for producing a lactic acid solution according to claim 6 , wherein a medium containing the carbon-based adsorbent and / or the carbon-based adsorbent composition is used for the lactic acid fermentation.

9. Producing a lactic acid solution by the method for producing a lactic acid solution according to any one of claims 1 to 8; synthesizing a lactic acid derivative using the lactic acid solution; A method for producing a lactic acid derivative, comprising:

10. A container and a carbon-based adsorbent and / or a carbon-based adsorbent composition packed in the container; Equipped with The container is configured to be capable of performing a first process and a second process, the first treatment comprises contacting lactic acid produced by lactic acid fermentation with the carbon-based adsorbent and / or the carbon-based adsorbent composition to adsorb the lactic acid onto the carbon-based adsorbent and / or the carbon-based adsorbent composition to obtain an adsorbed adsorbent; The system for producing a lactic acid solution, wherein the second treatment involves contacting the post-adsorption adsorbent with a solvent containing alcohol to extract the lactic acid into the solvent.

11. The system for producing a lactic acid solution according to claim 10 , further comprising a lactic acid production vessel that produces the lactic acid by lactic acid fermentation.

12. the carbon-based adsorbent composition and the post-extraction adsorbent comprise lactic acid immobilized on the carbon-based adsorbent; The system for producing a lactic acid solution according to claim 11, wherein the content of the immobilized lactic acid is 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent.

13. The system for producing a lactic acid solution according to claim 11 or 12, further comprising a carbon-based adsorbent and / or a carbon-based adsorbent composition filled in the lactic acid production vessel.

14. A carbon-based adsorbent composition comprising a carbon-based adsorbent and lactic acid immobilized on the carbon-based adsorbent, wherein the content of lactic acid immobilized on the carbon-based adsorbent is 1% by mass to 15% by mass relative to 100% by mass of the carbon-based adsorbent.

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