CN115724735A - Method for separating and extracting lactic acid, lactic acid product and preparation method thereof, and preparation method of calcium lactate particles - Google Patents
Method for separating and extracting lactic acid, lactic acid product and preparation method thereof, and preparation method of calcium lactate particles Download PDFInfo
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Abstract
The invention relates to the field of extraction and purification of biological fermentation monomers, and discloses a method for separating and extracting lactic acid, a lactic acid product and a preparation method thereof, and a preparation method of calcium lactate particles, wherein the method comprises the following steps: (1) Carrying out first extraction treatment on the first solution by adopting a first extraction system to obtain a first aqueous solution and a first organic solution; (2) Performing second extraction treatment on the first aqueous solution by using a second extraction system to obtain a second aqueous solution and a second organic solution; the first solution comprises lactic acid fermentation liquor and/or lactic acid fermentation treatment liquor; the second extraction system comprises a second complexing extraction agent which is an amide compound. The invention efficiently extracts lactic acid from lactic acid fermentation liquor by an extraction process, and the extraction process can be operated continuously and has the advantages of strong selectivity, low cost, high yield and the like.
Description
Technical Field
The invention relates to the field of extraction and purification of biological fermentation monomers, in particular to a method for separating and extracting lactic acid, a lactic acid product and a preparation method thereof, and a preparation method of calcium lactate particles.
Background
Lactic acid is a raw material for producing biodegradable polylactic acid, and with the increasing demand for biodegradable polymers, the lactic acid is produced industrially by a biological method at present, wherein starch, glucose, biomass and the like are used as raw materials, mold or lactic acid bacteria are inoculated, fermentation broth containing lactic acid or lactate is generated through fermentation, and then the lactic acid is obtained through separation. The lactic acid fermentation liquor is a system with very complex composition, and contains a large amount of thalli, proteins, residual sugar, pigments, inorganic salts, byproducts such as organic acid and other metabolites besides lactic acid. In particular, in the biological production of lactic acid using biological waste as raw material, the composition of the raw material is complex, wherein the carbon comprises pentose, hexose and various polysaccharides, and the content of pigment and inorganic salt is greatly higher than that of fermentation liquor using single starch as raw material, so that the extraction and purification of lactic acid in this field are difficult. In the actual production, the extraction cost of the lactic acid accounts for 50-60% of the total production cost, and the selection of the extraction method not only directly affects the quality and yield of the product, but also is a technical bottleneck and difficulty which restrict the industrialization of the lactic acid.
At present, methods for separating and extracting lactic acid from fermentation liquor mainly comprise a calcium salt crystallization method, an esterification hydrolysis method, an extraction method, a molecular distillation method, a membrane separation method, an adsorption method and an in-situ separation technology coupled with fermentation. In the lactic acid extraction process, lactic acid is firstly extracted from fermentation liquor by an extractant, and then is recovered from an extractant phase to another solvent by a back extraction mode. Zhu Hualei, etc. (research progress of lactic acid extraction technology, current chemical engineering, 2020, v.49, no.297 (10): 245-251) summarize the progress of extracting lactic acid relatively comprehensively, and the adoption of phosphorus oxygen, amine, alcohol, etc. is directed at the extraction of lactic acid molecules. The pH of the lactic acid fermentation broth is usually adjusted with calcium salts to obtain lactic acidExisting in the form of calcium lactate, and extracting after acidolysis with sulfuric acid. Xiulian Ren et al (AASRI Procedia 3 (2012) 341-350) use D2EHPA to extract Ca from lactic acid fermentation broth 2+ Allowing the aqueous phase H to stand + Rising, namely obtaining lactic acid from the water phase (calcium ions are not completely extracted). However, no system literature is reported on how to directly separate lactic acid from lactic acid fermentation liquor by using an extraction method.
Disclosure of Invention
The invention aims to develop a method for separating and extracting lactic acid. In order to achieve the above object, a first aspect of the present invention provides a lactic acid product having a chemical purity of 98wt% or more, further 98.5wt% or more, and/or an optical purity of > 99%.
In a second aspect, the present invention provides a method for separating and extracting lactic acid, the method comprising:
(1) Carrying out first extraction treatment on the first solution by using a first extraction system to obtain a first aqueous solution and a first organic solution, wherein the first extraction treatment enables at least one part of metal ions in the first solution to be extracted into the first organic solution;
(2) Performing second extraction treatment on the first aqueous solution by using a second extraction system to obtain a second aqueous solution and a second organic solution, wherein the second extraction treatment enables at least a part of lactic acid in the first aqueous solution to be extracted into the second organic solution;
wherein the first solution comprises a lactic acid fermentation liquid and/or a lactic acid fermentation treatment liquid;
the second extraction system comprises a second complex extraction agent, and the second complex extraction agent is an amide compound.
Preferably, the method further comprises step (3): and (3) carrying out back extraction on the second organic solution by adopting a back extraction agent to obtain a lactic acid aqueous solution or a lactate aqueous solution.
In a third aspect, the present invention provides a method for producing a lactic acid product, the method comprising: obtaining a lactic acid aqueous solution or a lactate aqueous solution by adopting the method of the second aspect of the invention, and then purifying the lactic acid aqueous solution to obtain a lactic acid product, or performing acidolysis on the lactate aqueous solution to obtain the lactic acid aqueous solution, and then purifying to obtain the lactic acid product;
further, the method of purification comprises: performing first-step concentration, activated carbon decolorization, further concentration dehydration and molecular distillation on the lactic acid aqueous solution to obtain a lactic acid product, wherein the concentration of lactic acid in the first-step concentration is 15-40wt%; or
Concentrating the lactic acid aqueous solution, decolorizing with activated carbon, purifying with resin, purifying with nanofiltration membrane, concentrating and dehydrating to obtain lactic acid product; or
And (3) concentrating, dehydrating and performing multi-stage molecular distillation on the lactic acid aqueous solution to obtain a lactic acid product, wherein the number of stages of the molecular distillation is 2 or more.
In a fourth aspect, the present invention provides a lactic acid product obtained by the preparation method according to the third aspect, wherein the chemical purity of the lactic acid product is 98wt% or more, further 98.5wt% or more, and further 99wt% or more; and/or
The optical purity of the lactic acid product is >99%; and/or
The content of residual metal ions in the lactic acid product is 100ppm or less, further 50ppm or less, and further 10ppm or less; and/or
The color number of the lactic acid product is less than 50; and/or
The total content of the residual extractant and diluent in the lactic acid product is 100ppm or less, further 50ppm or less, further 10ppm or less, and further 5ppm or less.
In a fifth aspect, the present invention provides a process for the preparation of calcium lactate particles, the process comprising: adding water to the second organic solution obtained by the method according to the second aspect of the present invention, neutralizing the second organic solution with a calcium source, separating to obtain a calcium lactate solution, and then sequentially concentrating and spray drying the calcium lactate solution to obtain calcium lactate particles, which can be used as a food additive material.
According to the technical scheme, the lactic acid is efficiently extracted from the lactic acid fermentation liquid or the lactic acid fermentation treatment liquid through the extraction process, so that the subsequent purification difficulty is reduced; meanwhile, the extraction method can be operated continuously, and has the advantages of large treatment capacity, strong selectivity, low cost, high yield, regenerative and cyclic extraction agent and the like. In addition, the extracted lactic acid is dissociated and recovered through a back extraction process, so that the whole lactic acid system is separated from metal ions to obtain a relatively pure lactic acid aqueous solution, and a high-purity and high-yield lactic acid product is obtained through a purification process; or neutralizing the second organic solution with calcium source, separating, concentrating, and spray drying to obtain calcium lactate granule as food additive material.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and these ranges or values should be understood to encompass values close to these ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
As described above, the first aspect of the present invention provides a lactic acid product, wherein the chemical purity of the lactic acid product is 98wt% or more, further 98.5wt% or more, and/or the optical purity of the lactic acid product is > 99%.
In some embodiments of the invention, the lactic acid product has a chemical purity of 99 wt.% or greater.
In some embodiments of the present invention, the content of residual metal ions in the lactic acid product is 100ppm or less, further 50ppm or less, and further 10ppm or less. Wherein, the metal ions include but are not limited to one or more of calcium ions, magnesium ions and iron ions, and calcium ions are preferred.
In some embodiments of the invention, the lactic acid product has a color number < 50.
In some embodiments of the invention, the total content of residual extractant and diluent in the lactic acid product is 100ppm or less, further 50ppm or less, further 10ppm or less, further 5ppm or less.
In some embodiments of the invention, the extractant comprises an acidic phosphorus-oxygen type extractant and an amide compound; wherein the general formula of the acidic phosphorus-oxygen type extractant is XYP (O) OH; x, Y is independently alkoxy or alkyl with C2-10 linear chain or branched chain structure; the general formula of the amide compound is RCONH 2 R is a C3 to C30 alkyl moiety, R may be saturated, mono-unsaturated or polyunsaturated, and R may also be of a straight or branched chain configuration.
In some embodiments of the present invention, the diluent comprises one or more of an ether compound, an ester compound, a linear, branched or cyclic alcohol compound, an alkane, an alkyl halide and an aromatic compound.
In a second aspect, the present invention provides a method for separating and extracting lactic acid, the method comprising:
(1) Carrying out first extraction treatment on the first solution by using a first extraction system to obtain a first aqueous solution and a first organic solution, wherein the first extraction treatment enables at least one part of metal ions in the first solution to be extracted into the first organic solution;
(2) Performing second extraction treatment on the first aqueous solution by using a second extraction system to obtain a second aqueous solution and a second organic solution, wherein the second extraction treatment enables at least a part of lactic acid in the first aqueous solution to be extracted into the second organic solution;
wherein the first solution comprises a lactic acid fermentation liquid and/or a lactic acid fermentation treatment liquid;
the second extraction system comprises a second complex extraction agent, and the second complex extraction agent is an amide compound.
In the present invention, the source of the first solution is not particularly limited, and the first solution is preferably obtained by fermenting lactic acid using agricultural and forestry waste as a raw material or by other means. The present invention is not particularly limited to the other routes, and examples thereof include those obtained by directly obtaining glucose, starch, and the like commercially, fermenting lactic acid using the obtained glucose, starch, and the like as a raw material, and those obtained by saccharifying and fermenting corn. The method for fermenting lactic acid in the present invention is not particularly limited, and a fermentation method that is conventional in the art may be used.
The source of the agricultural and forestry waste is not particularly limited, and includes, but is not limited to, one or more of straw (corn stover, wheat straw, rice straw, rape stalk, barley straw, oat straw, sorghum straw, etc.), rice hull, softwood, hardwood, tree branch, livestock manure, etc.
In some embodiments of the present invention, preferably, the first solution contains lactic acid, metal ions, pigments, proteins, saccharides, and water. In the invention, the lactic acid fermentation treatment liquid is obtained by centrifuging and filtering a lactic acid fermentation liquid to remove impurities such as thalli; or adjusting pH of the lactic acid fermentation liquid to 6-10.5, centrifuging, and filtering to remove impurities such as thallus. The centrifugation and filtration method of the present invention is not particularly limited, and a separation method that is conventional in the art may be used. The lactic acid fermentation liquid or the lactic acid fermentation treatment liquid can also be concentrated and then extracted with lactic acid, and the technicians in the field can select the lactic acid according to actual conditions.
The concentration of the metal ions in the first solution is selected from a wide range, and preferably, the concentration of the metal ions in the first solution is less than 5wt%, further less than 4wt%, and further less than 3 wt%.
The concentration of lactic acid in the first solution is selected from a wide range, and preferably, the concentration of lactic acid in the first solution is 50wt% or less, more preferably 30wt% or less, and still more preferably 5wt% or less.
In some embodiments of the present invention, preferably, the pH of the first solution is below 10.5, further between 4 and 9, further between 4.5 and 7; such as 4.5, 5.2, 5.6, 6.0, 7.0, 8.0, etc.
The present invention has a wide selection range of the metal ions, preferably, the metal ions include but are not limited to one or more of calcium ions, magnesium ions and iron ions.
In some embodiments of the present invention, preferably, in step (1), the volume ratio of the first extraction system to the first solution is (0.1-15): 1, further (0.2-10): 1, and further (0.25-8): 1.
In some embodiments of the present invention, preferably, the first extraction system comprises a first complexing extractant and optionally a first diluent; wherein the molar ratio of the first complexing extractant to the metal ions in the first solution is (0.1-50): 1, further (0.5-50): 1, further (1-30): 1, and further (2-20): 1; for example, 0.3.
In consideration of the viscosity and the layering effect of the first complexing extraction agent, the invention improves the physical and chemical properties of the first extraction system by adding the first diluent so as to better improve the extraction effect. The proportion relationship between the first complexing extractant and the first diluent is not particularly limited in the present invention, as long as the metal can be extracted, and the proportion relationship can be selected by a person skilled in the art according to actual conditions.
In some embodiments of the present invention, preferably, the first complex extractant is an acidic phosphorus-oxygen type extractant having the general formula XYP (O) OH; wherein X, Y is respectively and independently alkoxy or alkyl with linear or branched structure with 2-10 carbon atoms; more preferably, the alkoxy group or the alkyl group has a linear or branched structure having 5 to 10 carbon atoms. The acidic phosphorus-oxygen type extracting agent of the invention comprises but is not limited to 2-ethylhexyl phosphate mono-2-ethylhexyl (P507), dimethylheptyl methyl phosphate (P350), di (2-ethylhexyl) phosphate (P204) and the like.
In some embodiments of the present invention, preferably, the first diluent is selected from at least one of an ether compound, an ester compound, a linear, branched or cyclic alcohol compound, an alkane, an alkyl halide and an aromatic compound; further comprises at least one selected from the group consisting of ether compounds having 4 to 10 carbon atoms, ester compounds having 2 to 10 carbon atoms, linear, branched or cyclic alcohol compounds having at least four carbon atoms, linear or cyclic alkane compounds having five carbon atoms and mixtures thereof, alkyl halides having 1 to 3 carbon atoms and aromatic compounds.
In a specific embodiment of the present invention, the ether compound having 4 to 10 carbon atoms includes, but is not limited to, isopropyl ether, ethyl ether, n-butyl ether, and the like.
In a specific embodiment of the present invention, the ester compound having 2 to 10 carbon atoms is ethyl acetate and/or butyl acetate.
In a specific embodiment of the present invention, the linear, branched or cyclic alcohol compound having at least four carbon atoms is at least one selected from the group consisting of n-octanol, isooctanol, heptanol, cyclohexanol, isobutanol and decanol.
In a specific embodiment of the present invention, the linear or cyclic alkane compound having five carbon atoms and the mixture thereof includes, but is not limited to, one, two or more of kerosene, n-pentane, n-hexane, cyclohexane, n-dodecane, and n-tridecane.
In a specific embodiment of the present invention, the alkyl halide having 1 to 3 carbon atoms may be alkyl chloride and/or alkyl bromide, or alkyl mono-, di-, tri-, or tetrahalo, including but not limited to carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloroethane.
In a particular embodiment of the present invention, the aromatic compound includes, but is not limited to, benzene, toluene, ethylbenzene, chlorobenzene, xylene, and the like.
According to a preferred embodiment of the present invention, the first diluent is selected from at least one of dichloromethane, carbon tetrachloride, xylene, ethyl acetate, butyl acetate, isopropyl ether, n-octanol, isooctanol, heptanol, cyclohexanol, isobutanol and decanol.
In some embodiments of the present invention, preferably, in step (1), the difference Δ pH between the pH of the first aqueous solution and the pH of the first solution is > 0.5, further > 1, further > 2; for example, 0.5,1,1.5,2,3 or higher. The higher the absolute value of Δ pH, the more metal ions are extracted and less lactic acid is extracted.
In some embodiments of the invention, preferably, the pH of the first solution is greater than the pH of the first aqueous solution.
In some embodiments of the present invention, preferably, the first extraction treatment is performed so that the extraction rate of the metal ions is 30% or more, further 50% or more, further 85% or more, and further 90% or more. In the present invention, the extraction rate of the metal ions refers to the percentage of the metal ions entering the first organic solution to the metal ions in the first organic solution.
In the present invention, the temperature of the first extraction treatment is not particularly limited, and preferably, the temperature of the first extraction treatment is 10 to 95 ℃, further 20 to 60 ℃, and further 20 to 40 ℃, for example, 10 ℃, 22 ℃, 25 ℃, 28 ℃, 30 ℃, 32 ℃, 35 ℃, 38 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or the like.
In some embodiments of the present invention, preferably, the number of extraction stages of the first extraction treatment is 1 to 30, more preferably 1 to 20, and even more preferably 1 to 10, and the first extraction may be performed by a multi-stage counter-current or multi-stage cross-flow extraction method. The present invention may employ a concentration step between any two extraction stages.
The manner of contacting the first extraction system with the first solution to perform the first extraction treatment is not particularly limited in the present invention, and the extraction can be performed by a manner conventional in the art, for example, when the first extraction system only contains the first complex extractant, the first complex extractant is mixed with the first solution to achieve the contact between the first solution and the first complex extractant; when the first extraction system contains the first complexing extraction agent and the first diluent at the same time, the first complexing extraction agent and the first diluent are mixed firstly and then mixed with the first solution, so that the first solution is contacted with the first complexing extraction agent and the first diluent to extract.
In the invention, the metal ions in the first solution are subjected to complexing extraction by adopting the first extraction system, and the metal ions are transferred from the water phase to the organic phase, so that the metal ions are separated from lactic acid and the like in the fermentation liquor, at least most of the lactic acid is kept in the first aqueous solution, the effect of separating and purifying the lactic acid is achieved, and the process efficiency is improved.
In some embodiments of the present invention, preferably, in step (2), the volume ratio of the second extraction system to the first aqueous solution is (0.1-50): 1, further (0.2-40): 1, further (0.2-20): 1, further (0.5-10): 1;
in some embodiments of the present invention, preferably, the second extraction system further comprises a second diluent. The proportion relationship between the second complexing extraction agent and the second diluent is not particularly limited in the invention, and can be selected by a person skilled in the art according to actual conditions.
In some embodiments of the present invention, preferably, the molar ratio of the second complexing extractant to lactic acid in the first aqueous solution is (0.2-20): 1, further (0.5-10): 1, further (0.5-5): 1, further (1-5): 1.
In some embodiments of the present invention, preferably, in step (2), the amide compound has the formula RCONH 2 Wherein R is a C3 to C30 alkyl moiety, R may be saturated, mono-unsaturated or polyunsaturated, and R may also be a straight or branched chain structure.
In some embodiments of the invention, R may be a C8 to C20 or C15 to C23 alkyl moiety. In other embodiments, R may be a C21 alkyl moiety.
According to a preferred embodiment of the present invention, the amide-based compound includes, for example, but not limited to, N-bis (1-methylheptyl) acetamide (N503), stearic acid amide, erucic acid amide, palmitic acid amide, and the like.
In some embodiments of the present invention, preferably, the second diluent is selected from at least one of an ether compound, an ester compound, a linear, branched or cyclic alcohol compound, an alkane, an alkyl halide and an aromatic compound; further comprises at least one selected from the group consisting of ether compounds having 4 to 10 carbon atoms, ester compounds having 2 to 10 carbon atoms, linear, branched or cyclic alcohol compounds having at least four carbon atoms, linear or cyclic alkane compounds having five carbon atoms and mixtures thereof, alkyl halides having 1 to 3 carbon atoms and aromatic compounds. In the present invention, the second diluent may be the same as or different from the first diluent, and those skilled in the art may select the second diluent according to the actual situation, and further preferred substances of the second diluent are as described above, and are not described herein again.
In some embodiments of the present invention, preferably, in step (2), the number of extraction stages of the second extraction treatment is 1 to 24 stages, preferably 1 to 15 stages.
In some embodiments of the invention, preferably, the temperature of the second extraction treatment is below 50 ℃, preferably 10-30 ℃.
In the invention, the lactic acid in the first aqueous solution is subjected to complex extraction by adopting a second extraction system, and the lactic acid is transferred from the aqueous phase to the organic phase, so that the lactic acid is separated from residual metal ions in the fermentation liquor and the like, at least most of the lactic acid is extracted into the organic phase, the effect of separating and purifying the lactic acid is achieved, and the process efficiency is improved.
The extraction mode is not particularly limited, and the extraction can be carried out by adopting a mode of extracting calcium by adopting a first extraction system and then extracting lactic acid by adopting a second extraction system; alternatively, the metal ions and the lactic acid may be extracted by alternately extracting the metal ions and the lactic acid using a first extraction system and a second extraction system, and then separating the metal ions and the lactic acid. The method specifically comprises the following steps: firstly, carrying out first extraction treatment on a first solution by adopting a first extraction system to obtain a first aqueous solution and a first organic solution; then, carrying out second extraction treatment on the first aqueous solution by adopting a second extraction system to obtain a second aqueous solution and a second organic solution; and then, carrying out third extraction treatment on the second aqueous solution by adopting a first extraction system, and so on until the metal ions and the lactic acid respectively meet the required separation requirements. The method can be selected by the person skilled in the art according to the actual situation, and preferably is carried out by adopting a first extraction system to extract calcium and then adopting a second extraction system to extract lactic acid.
The extraction equipment used for performing the first extraction treatment and the second extraction treatment is not particularly limited, and may be any equipment conventional in the art, including, but not limited to, centrifugal extraction, mixer-settler, vibrating sieve plate column, rotating disk column, packed column, super-gravity rotating bed, and the like.
According to a preferred embodiment of the present invention, the method further comprises step (3): and carrying out back extraction on the second organic solution by using a back extraction agent to obtain an aqueous solution of lactic acid or lactate.
In some embodiments of the present invention, preferably, in step (3), the volume ratio of the stripping agent to the second organic solution is (0.1-100): 1, further (0.2-50): 1, further (0.2-30): 1.
in some embodiments of the invention, preferably, the stripping agent is water or an alkali solution. The alkali solution of the present invention can be selected from a wide range of solutions including, but not limited to, ammonia, sodium hydroxide solution, potassium hydroxide solution, calcium oxide solution, and combinations thereof.
In the present invention, when the second organic solution is back-extracted with water, it is preferable to back-extract with hot water at 50 to 120 ℃. Meanwhile, when the back extraction is performed by using water, one-stage extraction or more than two-stage extraction is preferable, and a concentration step may be performed between any two-stage back extraction.
In the present invention, when the second organic solution is back-extracted with an alkali solution, the addition manner of the alkali solution is not particularly limited, and the addition manner may be one-time feeding, or batch feeding, or feeding a plurality of alkali solutions separately, or once feeding after mixing the components. The concentration of the alkali solution in the present invention is not particularly limited, and the concentration of the alkali solution may be 0.01 to 8mol/L, further 0.05 to 5mol/L, further 0.1 to 5mol/L, for example, 0.5mol/L, 1mol/L, 1.5mol/L, 2.5mol/L, 3mol/L, 4mol/L, or the like.
According to a preferred embodiment of the present invention, the ratio of the alkali equivalent in the alkali solution to the molar concentration of lactic acid in the second organic solution, calculated as hydroxide, is (0.95-1.2): 1, further (0.98-1.1): 1.
In some embodiments of the invention, preferably the stripping is performed in stages from 1 to 24, more preferably from 1 to 15. The back extraction of the invention can be carried out in a multi-stage countercurrent mode.
In some embodiments of the invention, preferably the temperature of the stripping is from 10 to 120 ℃, further from 20 to 100 ℃, further from 20 to 95 ℃.
In one embodiment, the temperature during the back-extraction process can be from 10 ℃ to 120 ℃, further from 50 ℃ to 120 ℃, and further from 80 ℃ to 100 ℃, such as 60 ℃, 70 ℃, 90 ℃, and the like.
In another embodiment, the temperature of the stripping process may be 10 to 100 ℃, further 20 to 40 ℃, such as 25 ℃, 30 ℃, 35 ℃ and the like.
In the invention, the back extraction is carried out by contacting the back extractant with the second organic solution, so that the lactic acid in the organic phase is transferred to the aqueous phase, less metal ions are extracted to the aqueous phase as much as possible by controlling the conditions of the back extraction process, and more lactic acid is extracted to the aqueous phase.
In a third aspect, the present invention provides a method for producing a lactic acid product, the method comprising: the lactic acid aqueous solution or the lactate aqueous solution is obtained by the method, and then the lactic acid aqueous solution is purified to obtain the lactic acid product, or the lactate aqueous solution is firstly subjected to acidolysis to obtain the lactate aqueous solution, and then the lactic acid product is purified.
The purification method of the present invention is not particularly limited, and a purification method known in the art may be used.
In a specific embodiment of the invention, the method of purification comprises: and (2) carrying out first-step concentration, activated carbon decoloration, further concentration dehydration and molecular distillation on the lactic acid aqueous solution to obtain a lactic acid product, wherein the concentration of the lactic acid in the first-step concentration is 15-40wt%.
In another specific embodiment of the present invention, the method of purification comprises: the lactic acid water solution is subjected to concentration, activated carbon decoloration, resin purification, nanofiltration membrane purification, concentration and dehydration to obtain a lactic acid product.
In another specific embodiment of the present invention, the method of purification comprises: the lactic acid water solution is concentrated, dehydrated and subjected to multi-stage molecular distillation to obtain a lactic acid product, wherein the number of stages of the molecular distillation is 2 or more.
The fourth aspect of the present invention provides a lactic acid product obtained by the preparation method as described above, wherein the properties of the lactic acid product are as described above and will not be described herein again.
In a fifth aspect, the present invention provides a process for the preparation of calcium lactate particles, the process comprising: adding water to the second organic solution obtained by the method, neutralizing the second organic solution with a calcium source, separating to obtain calcium lactate solution, concentrating the calcium lactate solution, and spray drying to obtain calcium lactate granule as food additive material.
The calcium source of the present invention can be selected from a wide range of sources, including, but not limited to, calcium oxide, calcium carbonate, calcium hydroxide, and the like.
The present invention will be described in detail below by way of examples. In the following examples, various raw materials used are commercially available without specific description; the physical parameters related to the raw materials or the performance parameters of the product are obtained by measuring the physical parameters, the performance parameters and the like by adopting a conventional method in the field.
Preparation of the first solution
The preparation of the first solution with reference to the method disclosed in CN11294117a specifically comprises:
putting pretreated solid particle form corn straws with solid content of 30 (w/w)% into a fermentation tank as a raw material, adding cellulase with 5mg of protein per gram of straw (dry basis), and performing pre-saccharification for 6.5h at 48 ℃ and 200 rpm; after the pre-saccharification is finished, inoculating pediococcus acidilactici seed liquid into a fermentation tank according to the inoculation amount of 5% (v/v), simultaneously adding nutrient salts (10 g/L peptone, 10g/L yeast extract, 2g/L diammonium hydrogen citrate and 0.25g/L manganese sulfate monohydrate), adjusting and maintaining the pH value of fermentation liquor to be 5.4 by using calcium carbonate as a neutralizer in the fermentation process, fermenting for 96 hours at 42 ℃ and 200rpm, and then filtering to separate the fermentation liquor from the corn straw residues to obtain a first solution for later use, wherein the concentration of lactic acid in the first solution is 9wt%, and the concentration of calcium ions is 2wt%.
Extraction of lactic acid
Example 1
(1) Performing first extraction treatment on the first solution at the temperature of 24 ℃ by using a first extraction system (comprising P204 and n-octanol), wherein the extraction stages are 8 stages, so as to obtain a first aqueous solution (the pH value is 2.4) and a first organic solution, the volume ratio of the first extraction system to the first solution is 1.3, and the molar ratio of P204 to calcium ions in the first solution is 4:1; the first extraction treatment enables calcium ions in the first solution to be extracted into the first organic solution, so that the extraction rate of the calcium ions is 97.5%;
(2) And (2) carrying out second extraction treatment on the first aqueous solution at the temperature of 24 ℃ by adopting a second extraction system (comprising N, N-bis (1-methylheptyl) acetamide (N503) and cyclohexanol, wherein the extraction series is 8 stages, so as to obtain a second aqueous solution and a second organic solution, wherein the volume ratio of the second extraction system to the first aqueous solution is 1: the molar ratio of the 1,N, N-bis (1-methylheptyl) acetamide to the lactic acid in the first aqueous solution is 1.5, and the second extraction treatment enables the lactic acid in the first aqueous solution to be extracted into the second organic solution, so that the extraction rate of the lactic acid is 96.4%;
(3) And (3) carrying out back extraction on the second organic solution at 90 ℃ by adopting a back extractant (hot water), wherein the extraction stage number is 15 stages, so as to obtain a lactic acid aqueous solution, and the volume ratio of the back extractant to the second organic solution is 1:1, back extraction gave a back extraction of 97.5% of lactic acid and the product properties obtained are given in Table 1.
The remaining examples were carried out using the same procedure as in example 1, and the specific process conditions and the properties of the products obtained are shown in Table 1.
TABLE 1
Preparation of lactic acid product
Examples 6 and 7
And (3) sequentially carrying out concentration, activated carbon decolorization, resin purification, nanofiltration membrane purification and concentration dehydration on the lactic acid aqueous solution obtained in the embodiment 1 to obtain a lactic acid product.
And (3) sequentially carrying out concentration, activated carbon decolorization, resin purification, nanofiltration membrane purification and concentration dehydration on the lactic acid aqueous solution obtained in the embodiment 2 to obtain a lactic acid product.
The chemical purity, optical purity, color number, residual metal ion content and total residual extractant and diluent content of the resulting lactic acid product were determined to be listed in table 2.
TABLE 2
Preparation of calcium lactate particles
Example 8
Adding appropriate amount of water into the second organic solution obtained in step (2) of example 1, neutralizing the second organic solution with calcium carbonate to obtain calcium lactate, separating oil phase to obtain water phase as calcium lactate solution, concentrating the calcium lactate solution, and spray drying to obtain calcium lactate granule as food additive material.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (18)
1. A lactic acid product, characterized in that the chemical purity of the lactic acid product is above 98wt%, further above 98.5wt%, and/or the optical purity of the lactic acid product is > 99%.
2. The lactic acid product according to claim 1, characterized in that the chemical purity of the lactic acid product is 99wt% or more; and/or
The content of residual metal ions in the lactic acid product is 100ppm or less, more preferably 50ppm or less, and still more preferably 10ppm or less.
3. A lactic acid product according to claim 1 or 2, characterized in that the color number of the lactic acid product is < 50; and/or
The total content of the residual extractant and diluent in the lactic acid product is 100ppm or less, further 50ppm or less, further 10ppm or less, and further 5ppm or less.
4. A lactic acid product according to claim 3, characterized in that the extractant comprises an acidic phosphorus-oxygen type extractant and an amide-type compound; wherein the general formula of the acidic phosphorus-oxygen type extractant is XYP (O) OH; x, Y is independently alkoxy or alkyl with C2-10 linear chain or branched chain structure; the general formula of the amide compound is RCONH 2 R is a C3 to C30 alkyl moiety, R may be saturated, mono-unsaturated or polyunsaturated, and R may also be a straight or branched chain structure; and/or
The diluent comprises one or more of ether compounds, ester compounds, straight-chain, branched-chain or cyclic alcohol compounds, alkanes, alkyl halides and aromatic compounds.
5. A method for separating and extracting lactic acid, which is characterized by comprising the following steps:
(1) Carrying out first extraction treatment on the first solution by using a first extraction system to obtain a first aqueous solution and a first organic solution, wherein the first extraction treatment enables at least one part of metal ions in the first solution to be extracted into the first organic solution;
(2) Performing second extraction treatment on the first aqueous solution by using a second extraction system to obtain a second aqueous solution and a second organic solution, wherein the second extraction treatment enables at least a part of lactic acid in the first aqueous solution to be extracted into the second organic solution;
wherein the first solution comprises a lactic acid fermentation liquid and/or a lactic acid fermentation treatment liquid;
the second extraction system comprises a second complex extraction agent, and the second complex extraction agent is an amide compound.
6. The method according to claim 5, wherein the first solution is obtained by fermentation of lactic acid using agricultural and forestry waste as a raw material or by other means;
further, the agricultural and forestry waste is selected from at least one of straw, rice hull, softwood, hardwood, tree branches and livestock manure.
7. The method of claim 5, wherein the first solution comprises lactic acid, metal ions, pigments, proteins, sugars, and water;
wherein the concentration of metal ions in the first solution is below 5wt%, further below 4wt%, further below 3 wt%; and/or
The concentration of lactic acid in the first solution is 50wt% or less, further 30wt% or less, further 5wt% or less; and/or
The pH value of the first solution is below 10.5, further 4-9, further 4.5-7; and/or
The metal ion is at least one selected from calcium ion, magnesium ion and iron ion.
8. The method of claim 7, wherein in step (1), the volume ratio of the first extraction system to the first solution is (0.1-15): 1, further (0.2-10): 1, further (0.25-8): 1; and/or
The first extraction system comprises a first complex extractant and optionally a first diluent; wherein the molar ratio of the first complexing extractant to the metal ions in the first solution is (0.1-50): 1, further (0.5-50): 1, further (1-30): 1, and further (2-20): 1.
9. The process of claim 8, wherein the first complex extractant is an acidic phosphorus-oxygen type extractant having the general formula XYP (O) OH; wherein X, Y is respectively and independently alkoxy or alkyl with linear or branched structure with 2-10 carbon atoms; preferably alkoxy or alkyl with a linear or branched structure having 5 to 10 carbon atoms; further, the acidic phosphorus-oxygen type extracting agent is selected from at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, methyl heptyl phosphate and di (2-ethylhexyl) phosphoric acid; and/or
The first diluent is at least one selected from ether compounds, ester compounds, straight-chain, branched-chain or cyclic alcohol compounds, alkanes, alkyl halides and aromatic compounds; further selected from at least one of ether compounds with 4-10 carbon atoms, ester compounds with 2-10 carbon atoms, linear, branched or cyclic alcohol compounds with at least four carbon atoms, linear or cyclic alkane compounds with five carbon atoms and mixtures thereof, alkyl halides with 1-3 carbon atoms and aromatic compounds; further, the ether compound with 4-10 carbon atoms is selected from at least one of isopropyl ether, ethyl ether and n-butyl ether; the ester compound with the carbon atom number of 2-10 is ethyl acetate and/or butyl acetate; the straight chain, branched chain or cyclic alcohol compound at least containing four carbon atoms is at least one of n-octanol, isooctanol, heptanol, cyclohexanol, isobutanol and decanol; the straight chain or cyclic alkane compound containing five carbon atoms and the mixture thereof are selected from one, two or more of kerosene, n-pentane, n-hexane, cyclohexane, n-dodecane and n-tridecane; the alkyl halide with 1 to 3 carbon atoms is chloroalkane and/or bromoalkane, preferably at least one of carbon tetrachloride, trichloromethane, dichloromethane and 1,2-dichloroethane; the aromatic compound is at least one selected from benzene, toluene, ethylbenzene, chlorobenzene and xylene.
10. The method according to any one of claims 5 to 9, wherein in step (1) the difference between the pH of the first aqueous solution and the pH of the first solution Δ pH is > 0.5, further > 1, further > 2; and/or
The pH value of the first solution is greater than that of the first aqueous solution; and/or
The first extraction treatment is performed so that the extraction rate of metal ions is 30% or more, further 50% or more, further 85% or more, and further 90% or more; and/or
The temperature of the first extraction treatment is 10-95 ℃, further 20-60 ℃, and further 20-40 ℃; and/or
The extraction stage number of the first extraction treatment is 1-30, preferably 1-20, and more preferably 1-10, and the first extraction adopts a multi-stage countercurrent or multi-stage cross-flow extraction mode.
11. The method according to any one of claims 5 to 10, wherein in step (2), the volume ratio of the second extraction system to the first aqueous solution is (0.1-50): 1, further (0.2-40): 1, further (0.2-20): 1, further (0.5-10): 1; and/or
The second extraction system further comprises a second diluent; and/or
The molar ratio of the second complexing extraction agent to the lactic acid in the first aqueous solution is (0.2-20): 1, further (0.5-10): 1, further (0.5-5): 1, further (1-5): 1.
12. The method of claim 11, whichCharacterized in that in the step (2), the general formula of the amide compound is RCONH 2 Wherein R is a C3 to C30 alkyl moiety, R may be saturated, mono-unsaturated or polyunsaturated, and R may also be a straight or branched chain structure; further, the amide-based compound is selected from at least one of N, N-bis (1-methylheptyl) acetamide, stearic acid amide, erucic acid amide and palmitic acid amide; and/or
The second diluent is at least one selected from ether compounds, ester compounds, straight-chain, branched-chain or cyclic alcohol compounds, alkanes, alkyl halides and aromatic compounds; further selected from at least one of ether compounds with 4-10 carbon atoms, ester compounds with 2-10 carbon atoms, linear, branched or cyclic alcohol compounds with at least four carbon atoms, linear or cyclic alkane compounds with five carbon atoms and mixtures thereof, alkyl halides with 1-3 carbon atoms and aromatic compounds; the ether compound with the carbon atom number of 4-10 is selected from at least one of isopropyl ether, diethyl ether and n-butyl ether; the ester compound with the carbon atom number of 2-10 is ethyl acetate and/or butyl acetate; the straight chain, branched chain or cyclic alcohol compound at least containing four carbon atoms is at least one of n-octanol, isooctanol, heptanol, cyclohexanol, isobutanol and decanol; the straight chain or cyclic alkane compound containing five carbon atoms and the mixture thereof are selected from one, two or more of kerosene, n-pentane, n-hexane, cyclohexane, n-dodecane and n-tridecane; the alkyl halide with 1-3 carbon atoms is chloroalkane and/or bromoalkane, preferably at least one of carbon tetrachloride, trichloromethane, dichloromethane and 1,2-dichloroethane; the aromatic compound is at least one selected from benzene, toluene, ethylbenzene, chlorobenzene and xylene.
13. The process according to any one of claims 5 to 12, wherein in step (2), the second extraction treatment has an extraction stage number of 1 to 24, preferably 1 to 15; and/or
The temperature of the second extraction treatment is below 50 ℃, preferably 10-30 ℃.
14. The method according to any one of claims 5 to 13, characterized in that the method further comprises step (3): and carrying out back extraction on the second organic solution by using a back extraction agent to obtain an aqueous solution of lactic acid or lactate.
15. The process according to claim 14, wherein in step (3), the volume ratio of the stripping agent to the second organic solution is (0.1-100): 1, further (0.2-50): 1, further (0.2-30): 1; and/or
The stripping agent is water or an alkali solution, wherein the molar concentration ratio of alkali equivalent in the alkali solution to lactic acid in the second organic solution is (0.95-1.2): 1, further (0.98-1.1): 1; and/or
The extraction stage number of the back extraction is 1-24 stages, preferably 1-15 stages; and/or
The back extraction temperature is 10-120 deg.C, further 20-100 deg.C, and further 20-95 deg.C.
16. A method of producing a lactic acid product, comprising: obtaining an aqueous lactic acid solution or an aqueous lactate solution by the method according to claim 14 or 15, and then purifying the aqueous lactic acid solution to obtain a lactic acid product, or performing acidolysis on the aqueous lactate solution to obtain an aqueous lactic acid solution, and then purifying to obtain a lactic acid product;
further, the method of purification comprises: performing first-step concentration, activated carbon decolorization, further concentration dehydration and molecular distillation on the lactic acid aqueous solution to obtain a lactic acid product, wherein the concentration of lactic acid in the first-step concentration is 15-40wt%; or
Concentrating the lactic acid aqueous solution, decolorizing with activated carbon, purifying with resin, purifying with nanofiltration membrane, concentrating and dehydrating to obtain lactic acid product; or
And (3) concentrating, dehydrating and performing multi-stage molecular distillation on the lactic acid aqueous solution to obtain a lactic acid product, wherein the number of stages of the molecular distillation is 2 or more.
17. A lactic acid product obtained by the production method according to claim 16, wherein the chemical purity of the lactic acid product is 98wt% or more, further 98.5wt% or more, and further 99wt% or more; and/or
The optical purity of the lactic acid product is more than 99 percent; and/or
The content of residual metal ions in the lactic acid product is 100ppm or less, further 50ppm or less, and further 10ppm or less; and/or
The color number of the lactic acid product is less than 50; and/or
The total content of the residual extractant and diluent in the lactic acid product is 100ppm or less, further 50ppm or less, further 10ppm or less, and further 5ppm or less.
18. A process for the preparation of calcium lactate particles, comprising: adding water to the second organic solution obtained by the process according to any one of claims 5-15, neutralizing the second organic solution with a calcium source, separating to obtain a calcium lactate solution, and concentrating and spray drying the calcium lactate solution to obtain calcium lactate particles, which can be used as a food additive material;
further, the calcium source is selected from at least one of calcium oxide, calcium carbonate and calcium hydroxide.
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