TWI811017B - Purification method of bio-indigo dye - Google Patents

Abstract

The present invention provides a purification method of bio-indigo dye. The method comprises the following steps: (1) providing a bio-indigo dye; (2) hydrolyzing the bio-indigo dye with a hydrolysis reagent, wherein the hydrolysis reagent is an acidic solution, an alkaline solution or a proteases solution; (3) purifying the hydrolyzed bio-indigo dye by filtration, extraction or filtration-extraction; and (4) drying the purified bio-indigo dye.

Description

Purification method of biomass indigo dye

The present invention relates to a purification method, in particular to a purification method of biomass indigo dye.

Indigo is a vat dye used to dye textile materials containing cellulose.

Indigo dye itself is insoluble in water. In order to apply it to general textile materials, it is necessary to reduce indigo to water-soluble leuco-indigo salt, and then pass the textile material through the aqueous solution containing this salt. Dyed textiles are obtained by attaching indigo salt to textile materials and then forming indigo by air oxidation.

As early as 2400 BC in the fifth dynasty of ancient Egypt, indigo dye has been used for dyeing. During the Shang and Zhou dynasties, China developed the dyeing technology by extracting indigo dyes from the horse bluegrass. The stems and leaves of Stroblianthes cusia and Indigofera tinctoria) are soaked in water for several days to make them rotten and then fished out. Add milk of lime (calcium hydroxide) to the leached juice, stir and mix quickly, called Make "playing blue". The juice that reacts with lime and air gradually produces indigo blue precipitates, and indigo blue foam appears on the water surface. The sediment is called "blue lake" or "blue mud". After the foam is picked up and dried, it is called "indigo flower", which is natural. Indigo dye. No matter whether it is blue indigo or indigo flower, its blue depth exceeds the original crop color, and there is "Xunzi. Encouraging Learning" "green, take it from blue and green from blue".

The above-mentioned natural indigo dye, its chemical reaction change is due to the water-soluble indican in the stems and leaves of indigo crops, which is decomposed into green water-soluble indoxyl after several days of soaking. Then, in the alkaline environment formed by milk of lime (calcium hydroxide), there is an oxidation reaction with oxygen in the air to produce two optical isomers: indigo, which is insoluble in water, and indirubin, which is insoluble in water. indirubin), the reaction formula is as follows:

Most of the indigo content in the stems and leaves of indigo-dyed plants is less than 1%, while the indigo content of "blue lake" or "indigo flower" obtained by indigo-dyed plants is about 2-10%. The plant indigo obtained by refining indigo or indigo flower can increase the indigo content to 30-40%, and the indirubin content to 0.1-0.6%, which is the common specification of commercially available plant indigo.

In 1880, the German chemist Bayer (Adolf von Baeyer, 1835-1917) successfully synthesized indigo from the reaction of phenylacetic acid and acetone in alkaline aqueous solution in the laboratory. As a result, Bayer was awarded the Nobel Prize in Chemistry in 1905. However, due to high production costs, corporate benefits have always been poor.

In 1897, the German BASF company further improved the synthesis process, using aniline, formaldehyde and hydrogen cyanide as raw materials to industrially produce indigo in large quantities. Since then, the production of natural indigo has declined, and synthetic dyes have become a new chemical industry. However, aniline, formaldehyde and hydrogen cyanide are all carcinogens and harmful to human body and environment.

In recent years, the textile industry has been regulated in the synthesis and use of dyestuffs. International brand owners have also jointly put forward the commitment of "Zero Discharge of Hazardous Chemicals (ZDHC)". Under the joint promotion of regulations and brand owners, the textile industry is going green Production has become a future trend, and the application of chemically synthesized indigo dyes is gradually limited.

Bio-indigo is an indigo dye obtained through biosynthesis (Synthetic Biology), and its source is plant extraction and modified microorganisms. At present, the indigo dye extracted from plants on the market only accounts for 1% of the total global demand, and the source of plants is often limited by factors such as arable land area, growth cycle, and climate change, which affect its batch quality and output. Depending on the purity, it will be 8-30 times higher than chemically synthesized indigo dye, so its application in the textile industry is also limited. In recent years, technologies such as Synthetic Biology, Metabolic Engineering, and Genome Editing have developed rapidly, and Biorefinery products have entered the market one after another. Through further design and modification of production strains, As well as the textile industry's demand for green dyes, microbial production of indigo dyes has once again attracted attention.

However, the indigo purity (indigo concentration) of the bio-indigo dye obtained by the current technology is about 30-60 wt%, and contains about 5 wt% indirubin, a considerable proportion of which is impurities. Therefore, there is a need for an efficient method for purifying indigo dye.

According to one embodiment of the present invention, a method for purifying a bioindigo dye is provided, comprising the following steps: (1) providing a bioindigo dye; (2) hydrolyzing the bioindigo dye with a hydrolysis reagent, the hydrolysis reagent being acidic solution, alkaline solution or proteolytic enzyme solution; (3) purifying the hydrolyzed bio indigo dye by filtration, extraction or first filtration and then extraction; and (4) drying the purified bio indigo dye.

In one embodiment, the source of the biomass indigo dye provided in step (1) is plant extraction or microbial fermentation metabolites.

In one embodiment, the indigo purity of the biomass indigo dye provided in step (1) is lower than 60%, and the indigo purity of the biomass indigo dye dried in step (4) is higher than 90%

In one embodiment, the biomass indigo dye provided in step (1) contains about 5 wt% indirubin, and the indirubin content of the biomass indigo dye dried in step (4) is 3 wt%. the following.

In one embodiment, the hydrolysis step of step (2) is performed at room temperature to 100°C.

In one embodiment, the acidic solution in step (2) is 1-18N acidic aqueous solution, the alkaline solution is 1-18N alkali metal hydroxide aqueous solution or organic base, and the proteolytic enzyme is fungal protease, bacterial protease, plant protease, gastric Aqueous solution of protease or trypsin.

In one embodiment, in the hydrolysis step of step (2), the amount of the hydrolysis reagent added is 3-7 times that of the biomass indigo dye.

In one embodiment, the filtering method in step (3) is suction filtration or dehydration filtration.

In one embodiment, the filtering method in step (3) includes passing the hydrolyzed raw indigo dye through a filter cloth, the filter cloth has a pore size of 1-20 μm, and an air permeability of 2-100 l/m ^2‧s .

In one embodiment, the material of the filter cloth includes polypropylene (PP), polyvinyl alcohol (vinylon), polyester (polyester) and polyamide (polyamide).

In one embodiment, the extraction method in step (3) uses a fat extractor, and the extraction solvent used is an organic solvent.

In one embodiment, the extraction solvent in step (3) can dissolve indirubin.

In one embodiment, the organic solvent in step (3) is alcohol, isopropanol, acetone, methyl ethyl ketone or cyclohexane.

The above-mentioned method uses the biomass indigo dye, meets the requirement of environmental protection, can greatly improve the purity of the dye, and is suitable for industrial application.

In order to make the above and other conveniences of the present invention clearer and easier to understand, the following specific embodiments are described in detail together with the accompanying drawings.

Figure 1 shows a method for purifying bioindigo dye according to an embodiment of the present invention, comprising the following steps: (1) providing a bioindigo dye; (2) hydrolyzing the bioindigo dye with a hydrolysis reagent; (3) purifying the hydrolyzed bio-indigo dye by filtration, extraction or first filtration and then extraction; and (4) drying the purified bio-indigo dye. After the bio-indigo dye has undergone the hydrolysis step of step (2), the purification step of step (3), and the drying step of step (4), the indigo purity of the indigo dye can be greatly improved, and the indirubin content of the indigo dye can be reduced .

"Indigo purity" refers to the concentration of indigo in indigo dye (calculated by weight percent wt%). Biomass indigo dyes extracted from plants or synthesized by microorganisms contain a large amount of protein and fat, and the purity of indigo is usually not high, about 30-60%, and contains about 5wt% indirubin. These components are all impurities to be removed.

The source of the biomass indigo dye in the embodiment of the present invention is plant extraction or microbial fermentation metabolites. Among them, the plant extraction is made from indigo-containing crops (such as Isatistinctoria L., Clerodendrum cyrtopphyllum, Polygonum tinctorium, Stroblianthes cusia and Indigofera tinctoria). Indigo is extracted from stems and leaves, which is a natural source of indigo. Another source of biomass indigo is genetically modified microorganisms that have the ability to use glutamic acid and/or its salts as a nitrogen source to grow and produce indigo.

Genetically modified microbial sources include bacteria and fungi. Bacteria include Escherichia, Enterobacter, Enterococcus, Lactobacillus, Lactococcus, Pseudomonas, Citrobacter Citrobacter, Corynebacterium, Erwinia, Klebsiella, Morganella, Pantoea, Pectinbacterium (Pectobacterium), Proteus, Salmonella, Serratia, Shigella and other bacteria. Examples of bacteria belonging to the genus Escherichia include Escherichia coli and the like. Also, Escherichia coli may include Escherichia coli BW25113, K12, DH5α, BL21, or XL1-blue.

Examples of microorganisms of fungal origin may include: Yallowia, Pichia, Rhodotorula, Saccharomyces, Dekkera ), Aspergillus, Kluyveromyces, Penicillium, Ustilago and other fungi. This embodiment can use one or more than one source of microorganisms, but the sources of microorganisms in this embodiment are not limited to the bacteria and fungi mentioned above.

The microbial indigo dye used in the examples of the present invention comes from the Industrial Technology Research Institute (ITRI), and is obtained according to the processes of its patents US10975243 and TW202026419A. But the present invention does not limit the source of biomass indigo dye.

The hydrolysis step (2) of the embodiment of the present invention is completed by mixing the biomass indigo dye with the hydrolysis reagent, stirring and heating to an appropriate temperature for 7-20 hours. Hydrolysis reagents include acidic solutions, alkaline solutions, or proteolytic enzyme solutions. The acidic solution is 1-18N acidic aqueous solution, the alkaline solution is 1-18N alkali metal hydroxide aqueous solution or organic base, and the proteolytic enzyme is an aqueous solution of fungal protease, bacterial protease, plant protease, pepsin or trypsin. In one embodiment, the added amount of the hydrolysis reagent is 3-7 times that of the biomass indigo dye.

Depending on the hydrolysis reagent, the hydrolysis step is carried out at room temperature to 100°C. For example, the reaction temperature of the proteolytic enzyme aqueous solution cannot be too high, for example, it should be lower than 60°C. When using acid or alkali aqueous solution as the hydrolysis reagent, it can be heated up to 100°C.

The purification step (3) of the embodiment of the present invention is to filter and extract the hydrolyzed product, or to filter and then extract for purification. Filtration can adopt the suction filter device as Fig. 2, or the dehydration filter device of Fig. 3, but the present invention is not limited to use these two kinds of filter devices.

Fig. 2 is a schematic diagram of the suction filter device. The suction filter device is composed of a white porcelain funnel 1, a glass conical suction bottle 2, one or more filter cloths 3 and a pump 4, and the glass conical suction bottle 2 is connected to the pump 4. The filter cloth 3 used in this implementation is made of polypropylene PP, a circular cloth sample with a diameter of 110 mm, the hole size of the cloth sample is 1-20 μm, and the air permeability is between 2-100 l/m ² ‧s.

The solution that completed the hydrolysis reaction was cooled to room temperature, and the filter cake was collected by suction filtration. Preferably, after the filter cake that has been filtered for the first time is added to 2.5 times by weight of deionized water for washing, the second filtration is performed. This cleaning step can be repeated 1 to 2 times, and the filtered cake can be baked in a 105°C oven overnight to obtain the finished indigo.

Fig. 3 is a schematic diagram of the dehydration and filtration device. The dehydration filter device of the present embodiment is composed of a commercial dehydrator 5 and one or more filter bags 6, and uses a centrifugal method to discharge excess water. The model of the dehydrator 5 is, for example, Dennys SP-D055S, and its specification is an outer diameter of 35 cm × a height of 64.5 cm, a rotating speed of 2800 rpm, and a voltage of 110 V. The filter bag 6 is a bag that can be placed in the inner tank 7 of the dehydrator. It is made of polypropylene PP, with a diameter of 25 cm x a height of 42 cm. The size of the holes is 1-20 μm, and the air permeability is between 2-100 l/m ² ‧s.

Cool the solution that has completed the hydrolysis reaction to room temperature, and put it into the inner tank 7 of the dehydrator equipped with filter bag 6 in batches while the dehydrator 5 is running. After dehydration and filtration, take out the filter bag 6 and put it in an oven at 105°C for baking Overnight, the finished indigo can be obtained. Embodiment 1 : hydrolysis test

Table 1 shows the use of 17 different hydrolysis conditions (hydrolysis reagent type, concentration, heating temperature, stirring time) after the same 100 g of biomass indigo dye is hydrolyzed, purified by suction filtration, the yield and the measurement of indigo purity result. The purity of the raw indigo dye before hydrolysis is 40%, and contains 3% indirubin. In this embodiment, a hydrolysis reagent 5 times the weight of the biomass indigo dye is added, that is, 100 g of the biomass indigo dye and 500 g of the hydrolysis reagent are mixed. However, in other embodiments, 3-7 times the weight of the hydrolysis reagent can be added.

Table 1 Effect of different hydrolysis conditions on the purity of indigo dye experiment Hydrolysis reagent Heating temperature (℃) time (h) Yield (%) Indigo purity (%) 1 0.1 N NaOH RT 15 45.1 53.4 2 1 N NaOH RT 15 43.7 64.8 3 1 N NaOH 96 15 64.8 74.3 4 2 N NaOH 96 15 70.2 76.3 5 6 N NaOH 90 15 67.2 82.0 6 6 N NaOH 96 15 73.3 92.9 7 6 N NaOH 100 15 78.8 90.1 8 6 N NaOH 100 7 68.3 80.6 9 6 N NaOH 100 20 64.2 92.3 10 16 N NaOH 100 20 61.7 84.1 11 6 N KOH 96 15 72.7 80.6 12 4 N KOH 96 15 67.5 83.3 13 6 N HCl RT 15 55.1 52.3 14 6 N HCl 96 15 65.1 86.8 15 18 NH ₂ SO ₄ 100 15 63.3 79.7 16 3% protease enzyme* 56 15 76.6 72.0 17 3% Trypsin** 45 15 70.2 76.1 *Protease enzyme was purchased from Hengzhou Industry, product model: Alcalase 2.4L FG, activity 2.4 AU-A/g. **Trypsin was purchased from Hengzhou Industry, product model: Formea TL 1200 BG, activity 1200 KMTU/g.

Experiments 1-12 in Table 1 show that when the hydrolysis reagent is an alkali, increasing the alkali concentration (0.1N-16N) and increasing the hydrolysis temperature (room temperature to 100°C) can both increase the yield and purity of indigo, and simultaneously increase the alkali concentration and The hydrolysis temperature achieves the highest purity. Experiments 13-15 used acid as the hydrolysis reagent, and showed the same trend. Increasing the acid concentration and hydrolysis temperature could obtain higher yield and purity of indigo, but the purity of the product was lower than that of the alkaline hydrolysis reagent. In this embodiment, it is found that if acid or alkali is used as the hydrolysis reagent, the equivalent concentration should preferably be between 1N-18N, so as to have a better hydrolysis effect and increase the purity of indigo.

In experiments 16-17, commercially available proteolytic enzymes were used as hydrolysis reagents, heated to 45-56°C at pH=9, and hydrolyzed for 15 hours, the yield and purity of indigo dye could also be increased to over 70%.

From experiments 1-17 in Table 1, it can be seen that acid, alkali, and protease are used as hydrolysis reagents, which can effectively improve the purity of indigo dye. Among them, the hydrolysis conditions of high concentration of alkali (6N NaOH) combined with high temperature (100 ℃) and hydrolysis for 15 hours, Optimum yield and purity can be achieved. Embodiment 2 : large weight hydrolysis test

Add 5000 g of biomass indigo dye to 22800 g of 6N aqueous sodium hydroxide solution, stir at 100°C for 15 hours, and then cool down to room temperature. Add deionized water to 100 L, dehydrate and filter, take the filter cake, add deionized water to a total volume of 100 L, homogenize and stir evenly, dehydrate and filter again for purification. The filter cake of the secondary filtration was dried to obtain 3856 g of finished indigo dye, with a yield of 77.1%. The purity of the finished indigo was 92.5% by LC/PDA analysis.

Examples 1-17 in Table 1 are all small-scale reactions of 100 grams, but the purification method of this embodiment can also be applied to large-scale reactions of kilograms. For example, the above single batch can carry out the hydrolysis reaction of 5 kg of biomass indigo dye, and the dehydration and filtration method can also be used to achieve a single batch of 5 kg. Embodiment 3 : extraction test

Experiments 18-38 of this embodiment are the indigo dyes of Table 1 Experiment 4 (hydrolysis conditions: hydrolysis reagent 2N NaOH, heating temperature 96°C, heating time 15h, yield 70.2%, indigo purity 76.3%), and then with different After the extraction solvent is purified, its indigo purity and indirubin content are compared. In experiment 38, the unhydrolyzed biomass indigo dye (indigo purity 40%, indirubin 3%) was directly extracted, and the indigo purity and indirubin content were compared.

Fig. 4 is a schematic diagram of the extraction device, which uses a known fat extractor 5 (also known as a Soxhlet tube) for extraction. Take 15 grams of indigo dye dried in Experiment 4, put it into a cylindrical filter paper 6 (ADVANTEC 86R, ID 26 mm, OD 30 mm, L 100 mm ), and then put the cylindrical filter paper 6 into a 250 ml fat extractor 5 In addition, 105 g of solvent was added to the flat-bottomed flask below, and heated to reflux for 20 hours. Take out the cylindrical filter paper, place it in an oven at 105°C, dry and grind it to obtain the purified indigo dye. The test results of different extraction solvents are summarized in Table 2.

Table 2 Effects of different extraction solvents on the purity of indigo dye and the content of indirubin experiment extraction solvent Before extraction (%) After extraction (%) Yield (%) indigo Indirubin indigo Indirubin 18 Acidic water (pH=4.03) 76.3 1.65 77.6 1.63 98.4 19 Acidic water (pH=5.13) 76.3 1.65 78.3 1.64 98.7 20 Acidic water (pH=6.05) 76.3 1.65 75.0 1.69 99.0 twenty one Neutral water (pH=7.08) 76.3 1.65 75.3 1.68 98.5 twenty two Alkaline water (pH=9.10) 76.3 1.65 76.8 1.65 98.6 twenty three Alkaline water (pH=11.06) 76.3 1.65 77.1 1.63 97.9 twenty four water 76.3 1.65 79.5 1.39 96.3 25 Ethylene glycol 76.3 1.65 79.7 1.59 94.1 26 diethylene glycol 76.3 1.65 77.3 1.51 93.6 27 2-Methyl-2,4-pentanediol 76.3 1.65 75.6 1.68 94.6 28 Dimethylformamide 76.3 1.65 85.6 1.64 79.1 29 ethanol 76.3 1.48 93.0 0.87 93.1 30 Isopropanol 76.3 1.48 82.7 1.20 94.9 31 Isooctyl alcohol 76.3 1.65 77.7 1.31 95.1 32 Diethylene glycol monobutyl ether 76.3 1.65 77.9 1.47 94.4 33 Dipropylene glycol methyl ether 76.3 1.65 74.7 1.64 93.4 34 Ethylene glycol butyl ether 76.3 1.65 75.5 1.73 96.3 35 acetone 76.3 1.65 84.2 1.08 92.3 36 methyl ethyl ketone 76.3 1.48 92.1 0.50 90.6 37 Cyclohexane 76.3 1.65 90.0 0.72 82.8 38 Methyl ethyl ketone (unhydrolyzed) 40 3 51.2 1.86 -

It can be seen from Table 2 that after the hydrolysis reaction in Experiment 4, the indigo purity of the original biomass indigo dye has been increased from 40% to 76%, and the indirubin content has been reduced from 3 wt% to about 1.65 wt%. And then through solvent extraction, the indirubin content in the bioindigo dye can be further reduced from the original 1-3 wt% to 0.5-1 wt%, so that the purity of indigo is further improved.

However, not all extraction solvents have a purification effect. The experiments in Table 2 found that no matter whether it is acidic aqueous solution, alkaline aqueous solution or neutral water, there is no purification effect, and organic solvents can effectively reduce the content of indirubin. The effect is better, provided that the solvent must be able to dissolve indirubin.

In addition, from Experiment 38 in Table 2, it can be seen that the single extraction, that is, the extraction of unhydrolyzed dyes, still has the effect of reducing the content of indirubin and improving the purity of indigo, but the improvement of indirubin purity is not as good as the reduction of indirubin. Extraction purification steps. Embodiment 4 cotton yarn dyeing test

This experiment compares the dyeing ability of the bioindigo dye purified by the purification method of the embodiment of the present invention and the chemically synthesized indigo dye. Prepare the mother liquor of the dye solution according to the formula in Table 3. Take 20 g of dye, 16 g of sodium hydroxide (NaOH) and 20 g of sodium hydrosulfite (Na ₂ S ₂ O ₄ ) respectively and put them into a 1000 ml beaker, add deionized water to the total weight 500 g, stirred for 2 hours, the solution was transparent amber, and its acid-base value (pH) and potential value (mV) were measured.

Table 3 Dye liquor mother liquor formula Experimental drug name 39 40 Chemical Indigo Dye* (g/l) 40 Biomass indigo dye** (g/l) 40 NaOH (g/l) 32 32 Na ₂ S ₂ O ₄ (g/l) 40 40 pH 11.28 11.40 mV -979 -967 *The indigo concentration of chemical indigo dye is 88.0%, and the indirubin content is 0.31%. 0.5%

It can be known from Table 3 that at similar indigo concentrations, the chemical indigo dye and the bio-indigo dye in this example have similar pH values and potentials.

Next, take 30 ml of the mother liquor of the dye solution and add deionized water to dilute it to 500 ml to obtain a working solution, and check its pH and mV value again. Dyeing operation with working liquid, turn on the pad dyeing machine, set the pressure to 2 kg/cm ² , take the marked cotton yarn, put it in the working dyeing liquid in the pressure suction tank and soak it for 20 seconds, and then suck it through the pad dyeing machine. Then oxidize in the air for 1 minute, wash in overflow water at room temperature for 10 seconds, then suck it through a pressure dyeing machine, and finally put it in a 60°C oven to dry for 60 minutes.

Finally, using Datacolor Spectro 1000 spectrometer, with the conditions of 26 mm aperture, D65 light source, and 10 degree angle, respectively to the dye liquor of Experiment 39 (chemical indigo dye) and Experiment 40 (biological indigo dye after purification of the present invention) The coloring strength of the fiber material dyed by the mother liquor is measured, and the coloring strength is calculated according to the formula of Kubelka-Munk Theory. Wherein take the fiber material after the dyeing solution mother liquor coloring of experiment 39 (chemical indigo dye) as standard sample, the coloring strength measured by its pressure suction 1, 3, 6 times is defined as 100, and with experiment 40 (the present invention The fiber material after dyeing of the dye liquor mother liquor of embodiment) is compared, and the results are shown in Table 4 below.

Table 4 Comparison of coloring strength of indigo dyed samples test project experiment DE* MI** Strength 39 Chemical indigo dye (standard sample) Suction 1 time 0 0 100 suck 3 times 0 0 100 Suck 6 times 0 0 100 40 Biomass indigo dye Suction 1 time 0.26 0.10 97.65 suck 3 times 1.39 0.19 110.29 Suck 6 times 1.46 0.22 125.94 DE*: Chromatic difference MI**: Metamerism coefficient

After the bioindigo dye of this embodiment is sucked 1-6 times, the color difference DE value of the standard sample is between 0-2, which means that the color difference between the two cannot be distinguished. And the metamerism index (MI, Metamerism-Index) is low, indicating that the dyed sample has the same color difference under different color temperature light sources, and it is a high-quality dye. In addition, the coloring strength (97.65) of the bio-indigo dye is close to that of the standard chemical indigo dye (100), and after repeated pressure suction tests, the coloring strength (110-125) is 10-10 higher than that of the chemical indigo dye 20%, indicating that more dye is attached to the fiber. Therefore, the dyeing effect of the bio-indigo dye treated by the purification method (hydrolysis, filtration, and extraction) of this embodiment is better than that of the chemical indigo dye. same staining effect.

Accordingly, the method for purifying bio-indigo dyes provided in this example can not only greatly increase the indigo purity of bio-indigo dyes, reduce the concentration of indirubin, and approach chemical indigo dyes, but also surpass chemical indigo dyes in terms of coloring strength. , can reduce the amount of dye, not only environmentally friendly but also can reduce production costs.

1: white porcelain funnel

2: glass conical pumping bottle

3: filter cloth

4: Pump

5: Dehydrator

6: Filter bag

7: inner tank

8: Fat extractor

9: Cylindrical filter paper

Fig. 1 is a flow chart of a method for purifying biomass indigo dye according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of the suction filter device;

Fig. 3 is a schematic diagram of a dehydration filter device;

Figure 4 is a schematic diagram of the extraction device.

Claims (12)

A method for purifying a bioindigo dye, comprising: (1) providing a bioindigo dye, wherein the source of the bioindigo dye is a microbial fermentation metabolite; (2) hydrolyzing the bioindigo dye with a hydrolysis reagent, the hydrolysis The reagent is an acidic solution, an alkaline solution or a proteolytic enzyme solution; (3) purifying the hydrolyzed bioindigo dye by filtration, extraction or first filtration and then extraction; and (4) drying the purified bioindigo dye. Purification method as described in claim item 1, wherein the indigo purity of the biomass indigo dye provided in the step (1) is lower than about 60%, and the indigo purity of the biomass indigo dye completed in the step (4) is dried higher than about 90% . Purification method as described in claim item 1, wherein the biomass indigo dye provided in the step (1) contains about 5wt% indirubin, and the indirubin of the biomass indigo dye that has been dried in the step (4) The red content is about 3 wt% or less. The purification method as claimed in item 1, wherein the hydrolysis step of step (2) is carried out at room temperature to 100°C. The purification method as described in claim item 1, wherein the acidic solution is 1-18N acidic aqueous solution, the alkaline solution is 1-18N alkali metal hydroxide aqueous solution or organic base, and the proteolytic enzyme is fungal protease, bacterial protease, plant protease, Aqueous solution of pepsin or trypsin. The purification method as claimed in item 1, wherein in the hydrolysis step of step (2), the amount of the hydrolysis reagent added is 3-7 times that of the biomass indigo dye. The purification method as described in claim item 1, wherein the filtration method in step (3) is air suction filtration or dehydration filtration. Purification method as described in claim item 7, wherein the filtration method in step (3) comprises making the raw indigo dye after hydrolysis pass through a filter cloth, the pore size of the filter cloth is 1-20 μm, and the air permeability is between 2 -100 l/m ² . s. The purification method as claimed in item 8, wherein the material of the filter cloth includes polypropylene (PP), polyvinyl alcohol (vinylon), polyester (polyester) and polyamide (polyamide). The purification method as claimed in item 1, wherein the extraction method in step (3) uses a fat extractor, and the extraction solvent used is an organic solvent. The purification method as claimed in item 10, wherein the organic solvent can dissolve indirubin. The purification method as described in claim item 10, wherein the organic solvent is alcohol, isopropanol, acetone, methyl ethyl ketone or cyclohexane.