阅读说明：本技术 一种从大曲酒副产物黄水中分离提取乳酸的方法 (Method for separating and extracting lactic acid from daqu liquor by-product yellow water ) 是由 段兆法 李永庆 谈志新 于 2019-08-30 设计创作，主要内容包括：本发明公开了一种从大曲酒副产物黄水中分离提取乳酸的方法,涉及酿酒副产物利用技术领域,包括以下步骤：(1)离心过滤；(2)脱色处理；(3)树脂预处理；(4)树脂吸附；(5)洗脱液浓缩。本发明通过离心处理先除去黄水中的固体悬浮物和沉淀,再经脱色除去黄水中的色素杂质,最后通过离子交换树脂来分离出乳酸,整个方法操作简单易行,能使黄水中乳酸的回收率达到75％以上,乳酸纯度达到80％以上。(The invention discloses a method for separating and extracting lactic acid from daqu liquor by-product yellow water, which relates to the technical field of brewing by-product utilization and comprises the following steps: (1) centrifuging and filtering; (2) carrying out decoloring treatment; (3) resin pretreatment; (4) resin adsorption; (5) the eluate is concentrated. The invention firstly removes solid suspended substances and precipitates in the yellow water through centrifugal treatment, then removes pigment impurities in the yellow water through decoloration, and finally separates out the lactic acid through ion exchange resin, the whole method is simple and easy to operate, the recovery rate of the lactic acid in the yellow water can reach more than 75 percent, and the purity of the lactic acid can reach more than 80 percent.)

1. A method for separating and extracting lactic acid from yellow water which is a byproduct of Daqu liquor is characterized in that: the method comprises the following steps:

(1) centrifugal filtration: centrifuging yellow water, filtering to remove precipitate, and collecting filtrate;

(2) and (3) decoloring treatment: slowly adding a decolorizing agent into the filtrate under stirring, standing for decolorizing, filtering, separating out active carbon, and collecting the decolorized solution;

(3) resin pretreatment: loading the ion exchange resin into an elution column, soaking the ion exchange resin in an ethanol solution with the volume fraction of 60-70%, then sequentially soaking the ion exchange resin in a hydrochloric acid solution with the mass fraction of 3-5% and a sodium hydroxide solution with the mass fraction of 3-5%, and leaching the ion exchange resin to be neutral by using clear water after each soaking treatment;

(4) resin adsorption: loading the pretreated ion exchange resin into an elution column, loading the decolored yellow water solution on the column, eluting with 3-5% sulfuric acid solution by mass, and collecting the eluent;

(5) concentrating the eluent: and concentrating the eluent under reduced pressure, and obtaining a lactic acid product after the water is completely removed.

2. The method for separating and extracting lactic acid from daqu liquor by-product yellow water according to claim 1, characterized in that: the rotation speed of the centrifugal treatment is 5000-.

3. The method for separating and extracting lactic acid from daqu liquor by-product yellow water according to claim 1, characterized in that: the decolorizing agent is activated carbon, and the decolorizing time is 5-12 h.

4. The method for separating and extracting lactic acid from daqu liquor by-product yellow water according to claim 1, characterized in that: the soaking time of the ethanol solution is 3-5h, the soaking time of the hydrochloric acid solution is 2-4h, and the soaking time of the sodium hydroxide solution is 2-4 h.

5. The method for separating and extracting lactic acid from daqu liquor by-product yellow water according to claim 1, characterized in that: the mass ratio of the filtrate to the decolorizing agent is 100: 1-5.

6. The method for separating and extracting lactic acid from daqu liquor by-product yellow water according to claim 1, characterized in that: the column flow rate of the yellow water decoloring liquid is 1-3 BV/h.

7. The method for separating and extracting lactic acid from daqu liquor by-product yellow water according to claim 1, characterized in that: the elution flow rate of the sulfuric acid solution is 2-5 BV/h.

8. The method for separating and extracting lactic acid from daqu liquor by-product yellow water according to claim 1, characterized in that: the ion exchange resin is one of D301-R macroporous alkalescent styrene anion exchange resin, D315 macroporous alkalescent acrylic anion exchange resin, D201 macroporous strongly basic styrene anion exchange resin, X-5 macroporous adsorption resin and S-8 macroporous adsorption resin.

The technical field is as follows:

the invention relates to the technical field of brewing by-product utilization, in particular to a method for separating and extracting lactic acid from yellow water which is a by-product of Daqu liquor.

Background art:

daqu liquor is a distilled liquor prepared by using sorghum and wheat as main raw materials and using the large area as a saccharification leavening agent through the steps of stewing, saccharifying, fermenting, distilling, storing and blending. Organic acid generated in the fermentation process of fermented grains in the pit is a flavor-generating precursor substance, and the proper content of the organic acid is also one of the sources of flavor-developing substances of the white spirit. The yellow water is a byproduct of the Daqu liquor, and the contained organic acids comprise acetic acid, propionic acid, butyric acid, lactic acid, heptanoic acid, caprylic acid, capric acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, eicosanoic acid, oleic acid, linoleic acid, 7-alkene hexadecanoic acid and the like, wherein the highest content of the lactic acid is up to 91 percent of the total acid in a cellar.

Lactic acid is an important raw material or additive in the industries of food, medicine, cosmetics, agriculture, environmental protection and the like. The COD of the yellow water of the Daqu liquor can reach 100000mg/L, the Daqu liquor is difficult to discharge after reaching the standard even after anaerobic-aerobic treatment, and after the lactic acid is extracted, the lactic acid with economic value can be obtained, the COD of the Daqu liquor can be greatly reduced, and the load of wastewater treatment is reduced.

At present, methods for extracting lactic acid include: calcium salt method, ion exchange resin adsorption method, bipolar membrane separation method, distillation method, solvent extraction method, and supercritical CO₂Extraction methods, and the like. The calcium salt method has a plurality of extraction steps, generates more corrosive solutions such as waste acid, waste alkali and the like, and has poor product quality. The distillation method comprises direct distillation and molecular distillation, the temperature and energy consumption are higher when the lactic acid is extracted by direct distillation, and the molecular distillation is more suitable for fermentation liquor with higher purity of the lactic acid. The solvent extraction method has low safety because some solvents used are toxic. The bipolar membrane separation method is suitable for extracting organic acid in fermentation liquor with simple product composition, and is easy to cause blockage and membrane pollution to yellow water with complex components, so that the extraction cost is increased. The ion exchange resin adsorption method is relatively mature, and the types of the ion exchange resins are many, and can be selected according to the properties of extracted substances. The invention realizes the high-efficiency extraction of the lactic acid in the yellow water by self-made ion exchange resin, and obviously improves the recovery rate of the lactic acid.

The invention content is as follows:

the technical problem to be solved by the invention is to provide a method for separating and extracting lactic acid from the yellow water which is a byproduct of Daqu liquor, wherein the method is simple and easy to operate, and can ensure that the recovery rate of the lactic acid in the yellow water reaches over 75 percent and the purity of the lactic acid reaches over 80 percent.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

a method for separating and extracting lactic acid from Daqu liquor by-product yellow water comprises the following steps:

(1) centrifugal filtration: centrifuging yellow water, filtering to remove precipitate, and collecting filtrate;

(2) and (3) decoloring treatment: slowly adding a decolorizing agent into the filtrate under stirring, standing for decolorizing, filtering, separating out active carbon, and collecting the decolorized solution;

(3) resin pretreatment: loading the ion exchange resin into an elution column, soaking the ion exchange resin in an ethanol solution with the volume fraction of 60-70%, then sequentially soaking the ion exchange resin in a hydrochloric acid solution with the mass fraction of 3-5% and a sodium hydroxide solution with the mass fraction of 3-5%, and leaching the ion exchange resin to be neutral by using clear water after each soaking treatment;

(4) resin adsorption: loading the pretreated ion exchange resin into an elution column, loading the decolored yellow water solution on the column, eluting with 3-5% sulfuric acid solution by mass, and collecting the eluent;

(5) concentrating the eluent: and concentrating the eluent under reduced pressure, and obtaining a lactic acid product after the water is completely removed.

The rotation speed of the centrifugal treatment is 5000-.

The decolorizing agent is activated carbon, and the decolorizing time is 5-12 h.

The soaking time of the ethanol solution is 3-5h, the soaking time of the hydrochloric acid solution is 2-4h, and the soaking time of the sodium hydroxide solution is 2-4 h.

The mass ratio of the filtrate to the decolorizing agent is 100: 1-5.

The column flow rate of the yellow water decoloring liquid is 1-3 BV/h.

The elution flow rate of the sulfuric acid solution is 2-5 BV/h.

The ion exchange resin is one of D301-R macroporous alkalescent styrene anion exchange resin, D315 macroporous alkalescent acrylic anion exchange resin, D201 macroporous strongly basic styrene anion exchange resin, X-5 macroporous adsorption resin and S-8 macroporous adsorption resin.

In order to further improve the recovery rate of lactic acid in the yellow water, the invention also prepares the macroporous adsorption resin by self, and the specific technical scheme is as follows:

the macroporous adsorption resin is prepared by carrying out suspension polymerization reaction on a skeleton raw material, a pore-forming agent, an initiator, a dispersing agent and deionized water, wherein the skeleton raw material is selected from divinylbenzene and N-hydroxyethyl acrylamide, the pore-forming agent is selected from isooctane or N-pentane, the initiator is selected from benzoyl peroxide, and the dispersing agent is selected from polyvinyl alcohol or carboxymethyl cellulose.

The reaction temperature of the suspension polymerization is 75-95 ℃.

The mass ratio of the framework raw material, the pore-foaming agent, the initiator, the dispersant and the deionized water is 80-120:100-150:0.5-1:5-10: 500-1000.

The amount of the divinyl benzene accounts for 70-85% of the mass of the framework raw material.

The specific preparation method of the macroporous adsorption resin comprises the following steps: adding a skeleton raw material, a pore-forming agent, an initiator and a dispersing agent into deionized water, heating to 75-85 ℃, carrying out heat preservation reaction for 8-12h, heating to 85-95 ℃, carrying out heat preservation reaction for 8-12h, filtering after the polymerization reaction is finished, washing the obtained solid phase with hot water at 85-95 ℃ to obtain white balls, loading the white balls into an elution column, introducing steam to elute residual pore-forming agent, and sieving to obtain the macroporous adsorption resin.

In order to further optimize the adsorption performance of the self-made macroporous adsorption resin on lactic acid, the invention also carries out modification treatment on the self-made macroporous adsorption resin, and utilizes the esterification reaction of hydroxyl introduced by N-hydroxyethyl acrylamide and carboxyl contained in histidine, and the specific technical scheme is as follows:

dissolving histidine in water, adding macroporous adsorption resin, dropwise adding 98% concentrated sulfuric acid, heating to 70-80 deg.C, reacting while maintaining the temperature, naturally cooling to room temperature, filtering, washing with water, and drying to obtain modified macroporous adsorption resin.

The molar dosage of the histidine is 1mol of histidine per mol of N-hydroxyethyl acrylamide, and the molar dosage of the concentrated sulfuric acid is 0.05mol of concentrated sulfuric acid per mol of N-hydroxyethyl acrylamide.

The invention has the beneficial effects that: the method firstly removes suspended solid and precipitate in the yellow water through centrifugal treatment, then removes pigment impurities in the yellow water through decoloration, and finally separates out the lactic acid through ion exchange resin, the whole method is simple and easy to operate, the recovery rate of the lactic acid in the yellow water can reach more than 75 percent, and the purity of the lactic acid can reach more than 80 percent; the recovery rate of lactic acid in the yellow water can reach more than 80% through self-made macroporous adsorption resin, the purity of the lactic acid can reach more than 85%, and the lactic acid with specific economic value can be obtained while the treatment difficulty of the yellow water waste liquid is reduced.

The specific implementation mode is as follows:

in order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

The yellow water as the by-product of the Daqu liquor used in the following examples is obtained from the same batch of yellow water as the by-product of the Daqu liquor produced by the company in 2018, 11 and 25 months, and the content of lactic acid is 3.81g/100 mL; the D315 macroporous alkalescent acrylic anion exchange resin is from Shanghai jin Kai resin science and technology Limited, and the D301-R macroporous alkalescent styrene anion exchange resin, the D201 macroporous alkalescent styrene anion exchange resin, the X-5 macroporous adsorption resin and the S-8 macroporous adsorption resin are all from the photo-assisted fine chemical research institute in Tianjin; divinylbenzene 80% divinylbenzene from Sigma-Aldrich; the polyvinyl alcohol is PVA-124 from conifer chemical Co., Ltd.