TW202402965A - 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 difficult to dissolve in water. In order to be applied to general textile materials, indigo needs to be reduced to water-soluble leuco-indigo salt (water-soluble leuco-indigo salt), and then the textile material is passed through an aqueous solution containing this salt. Indigo white salt is attached to textile materials, and then oxidized by air to form indigo, thereby producing dyed textiles.

Indigo dye has been used for dyeing as early as 2400 BC in the Fifth Dynasty of ancient Egypt. During the Shang and Zhou dynasties, China developed dyeing technology by extracting indigo dye from Malan grass. The method was as follows: indigo-containing crops (such as Isatistinctoria L., Clerodendrum cyrtophyllum, Polygonum tinctorium, The stems and leaves of Stroblianthes cusia and Indigofera tinctoria are soaked in water for several days to let them rot, then fish them out, add lime milk (calcium hydroxide) to the extracted juice, stir quickly and mix, and weigh As "playing blue". The juice reacting with lime and air gradually produces indigo precipitate, and there is indigo foam on the water surface. The precipitate 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. Regardless of indigo or indigo flowers, the depth of blue exceeds the color of the original crop, and "Xunzi. "Encouragement to Learning" the phrase "green, taken from blue and green from blue".

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

The indigo content in the stems and leaves of indigo plants is mostly less than 1%, while the indigo content of "indigo" or "indigo flowers" obtained by chopping indigo plants is about 2-10%. Refining plant indigo from blue lake or indigo flowers can increase the indigo content to 30-40% and the indirubin content to 0.1-0.6%. This is a common specification for commercially available plant indigo.

In 1880, the German chemist Adolf von Baeyer (1835-1917) successfully synthesized indigo in the laboratory from the reaction of phenylacetic acid and acetone in an alkaline aqueous solution. The reaction is as follows. This synthesis reaction opened the door to the artificial synthesis of indigo. This trend led to Bayer being awarded the 1905 Nobel Prize in Chemistry. However, due to high production costs, corporate performance has always been poor.

In 1897, the German BASF company further improved the synthesis process and used aniline, formaldehyde and hydrogen cyanide as raw materials to produce indigo on an industrial scale. 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 are harmful to the human body and the environment.

In recent years, the textile industry has been regulated in the synthesis and use of dyes. International brands have also jointly proposed the commitment of "Zero Discharge of Hazardous Chemicals (ZDHC)". With the joint promotion of regulations and brands, the textile industry has become green. Production has become a future trend, and the application of chemically synthesized indigo dyes is gradually restricted.

Bio-indigo is an indigo dye obtained through biosynthesis (Synthetic Biology), and its sources are plant extracts and modified microorganisms. Currently, 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 cultivated land area, growth cycle, climate change, etc., which affects its batch quality and output, and the unit price is Depending on the purity, it is 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 demand for green dyes in the textile industry, the production of indigo dye by microorganisms has once again attracted attention.

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

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

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

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 biomass indigo dye dried in step (4) has an indirubin content of 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 a 1-18N acidic aqueous solution, the alkaline solution is a 1-18N alkali metal hydroxide aqueous solution or an organic base, and the proteolytic enzyme is fungal protease, bacterial protease, plant protease, gastric protease, Aqueous solution of protease or trypsin.

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

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

In one embodiment, the filtration method in step (3) includes passing the hydrolyzed biomass indigo dye 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 .

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, isopropyl alcohol, acetone, methyl ethyl ketone or cyclohexane.

The above method uses biomass indigo dye, meets environmental protection requirements, 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, embodiments are given below and explained in detail with reference to the accompanying drawings.

Figure 1 shows a method for purifying biomass indigo dye according to an embodiment of the present invention, which includes the following steps: (1) providing biomass indigo dye; (2) hydrolyzing the biomass indigo dye with a hydrolysis reagent; (3) Purify the hydrolyzed biomass indigo dye by filtration, extraction, or filtration and then extraction; and (4) drying the purified biomass indigo dye. After the biomass indigo dye undergoes 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" means the concentration of indigo in the indigo dye (calculated as weight percent wt%). Biomass indigo dye extracted from plants or synthesized by microorganisms contains a large amount of protein and fat. 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 biomass indigo dye in the embodiment of the present invention is plant extract or microbial fermentation metabolite. Among them, plant extracts are made from indigo-containing crops (such as Isatistinctoria L., Clerodendrum cyrtophyllum, Polygonum tinctorium, Stroblianthes cusia and Indigofera tinctoria). Indigo is extracted from the stems and leaves, which is a natural source of indigo. Another source of biomass indigo dye is genetically modified microorganisms, which have the ability to use glutamic acid and/or its salts as a nitrogen source to grow and produce indigo dye.

Sources of genetically modified microorganisms include bacteria and fungi. Bacteria include Escherichia, Enterobacter, Enterococcus, Lactobacillus, Lactococcus, Pseudomonas, Citrobacter Citrobacter, Corynebacterium, Erwinia, Klebsiella, Morganella, Pantoea, Pectobacterium (Pectobacterium), Proteus, Salmonella, Serratia, Shigella and other bacteria. Examples of bacteria of the genus Escherichia include Escherichia coli and the like. In addition, Escherichia coli may include Escherichia coli BW25113, K12, DH5α, BL21, or XL1-blue.

Examples of microorganisms derived from fungi include: Yallowia, Pichia, Rhodotorula, Saccharomyces, Dekkera ), Aspergillus, Kluyveromyces, Penicillium, Ustilago and other fungi. One or more microbial sources may be used in this embodiment, but the microbial sources in this embodiment are not limited to the above-mentioned bacteria and fungi.

The microbial indigo dye used in the embodiments of the present invention comes from the Industrial Technology Research Institute (ITRI) and is produced according to its patented processes of US10975243 and TW202026419A. However, 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 biomass indigo dye and 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 a 1-18N acidic aqueous solution, the alkaline solution is a 1-18N alkali metal hydroxide aqueous solution or an 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 performed 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 involves filtering and extracting the hydrolyzed product, or filtering and then extracting for purification. Filtration can use an air extraction filter device as shown in Figure 2, or a dehydration filter device as shown in Figure 3, but the present invention is not limited to the use of these two filter devices.

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

The solution that has completed the hydrolysis reaction is cooled to room temperature, and the filter cake is collected by suction filtration. Preferably, the filter cake that has been filtered for the first time is washed with 2.5 times the weight of deionized water and then filtered for the second time. This cleaning step can be repeated 1 to 2 times. Place the filtered cake into a 105°C oven and bake it overnight to obtain the finished indigo product.

Figure 3 is a schematic diagram of the dewatering and filtering device. The dewatering and filtering device of this embodiment is composed of a commercial dewatering machine 5 and one or more filter bags 6, and uses a centrifugal method to drain excess water. The model of the dehydrator 5 is, for example, Dennys SP-D055S, and its specifications are 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 × a height of 42 cm. It has a hole size of 1-20 μm and an air permeability of 2-100 l/m ² ‧s.

The solution that has completed the hydrolysis reaction is cooled to room temperature, and is added in batches to the inner tank 7 of the dehydrator equipped with the filter bag 6 while the dehydrator 5 is running. After dehydration and filtration, the filter bag 6 is taken out and placed in a 105°C oven for baking. Overnight, you can get the finished indigo product. Example 1 : Hydrolysis test

Table 1 shows the measurement of the yield and indigo purity using 17 different hydrolysis conditions (hydrolysis reagent type, concentration, heating temperature, stirring time) to hydrolyze the same 100 g biomass indigo dye and then purify it by suction filtration. result. The purity of the pre-hydrolyzed indigo dye is 40% and contains 3% indirubin. In this embodiment, a hydrolysis reagent that is 5 times the weight of biomass indigo dye is added, that is, 100 g of biomass indigo dye and 500 g of hydrolysis reagent are mixed. However, in other embodiments, 3-7 times the weight of the hydrolysis reagent may 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 0.1N NaOH RT 15 45.1 53.4 2 1N NaOH RT 15 43.7 64.8 3 1N NaOH 96 15 64.8 74.3 4 2N NaOH 96 15 70.2 76.3 5 6N NaOH 90 15 67.2 82.0 6 6N NaOH 96 15 73.3 92.9 7 6N NaOH 100 15 78.8 90.1 8 6N NaOH 100 7 68.3 80.6 9 6N NaOH 100 20 64.2 92.3 10 16N NaOH 100 20 61.7 84.1 11 6N KOH 96 15 72.7 80.6 12 4N 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 Industrial, product model: Alcalase 2.4L FG, activity 2.4 AU-A/g. **Trypsin was purchased from Hengzhou Industrial, 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 increase the yield and purity of indigo, while increasing the alkali concentration and The highest purity can be achieved at hydrolysis temperatures. Experiments 13-15, using acid as the hydrolysis reagent, also show the same trend. Increasing the acid concentration and hydrolysis temperature can obtain higher indigo yield and purity, but the product purity is lower than that of the alkaline hydrolysis reagent. This example found that if acid or alkali is used as the hydrolysis reagent, the equivalent concentration should preferably be between 1N and 18N to achieve 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 under pH=9, and hydrolyzed for 15 hours. The yield and purity of indigo dye could also be increased to more than 70%.

It can be seen from Experiments 1-17 in Table 1 that acids, alkalis, and proteases can be used as hydrolysis reagents to effectively improve the purity of indigo dye. Among them, high-concentration alkali (6N NaOH) combined with high temperature (100 ℃) and hydrolysis conditions of 15 hours can effectively improve the purity of indigo dye. Optimal yield and purity can be achieved. Example 2 : Large weight hydrolysis test

Add 5000 g of biomass indigo dye to 22800 g of 6N sodium hydroxide aqueous solution, stir at 100°C for 15 hours, and then cool 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, mix homogeneously, and dehydrate, filter and purify again. The filter cake from the secondary filtration was dried to obtain 3856 g of finished indigo dye, with a yield of 77.1%. After LC/PDA analysis and testing, the purity of this indigo finished product is 92.5%.

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

Experiments 18-38 of this embodiment are based on the indigo dye from Experiment 4 in Table 1 (hydrolysis conditions: hydrolysis reagent 2N NaOH, heating temperature 96°C, heating time 15h, yield 70.2%, indigo purity 76.3%), and then use different After the extraction solvent is purified, its indigo purity and indirubin content are compared. Experiment 38 used unhydrolyzed biomass indigo dye (indigo purity 40%, indirubin 3%) for direct extraction, and compared the indigo purity and indirubin content.

Figure 4 is a schematic diagram of an extraction device, which uses a conventional fat extractor 5 (also known as a Soxhlet tube) for extraction. Take 15 grams of the dried indigo dye from Experiment 4, put it into the cylindrical filter paper 6 (ADVANTEC 86R, ID 26 mm, OD 30 mm, L 100 mm), and then put the cylindrical filter paper 6 into the 250 ml fat extractor 5 , add 105 g of solvent to the flat-bottomed flask below, and heat to reflux for 20 hours. Take out the cylindrical filter paper, place it in a 105°C oven, dry and grind it to obtain 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 indirubin content 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 Isopropyl alcohol 76.3 1.48 82.7 1.20 94.9 31 Isooctanol 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 (not hydrolyzed) 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 can be increased from 40% to 76%, and the indirubin content is reduced from 3 wt% to approximately 1.65 wt%. Through solvent extraction, the indirubin content in the biomass indigo dye can be further reduced from the original 1-3 wt% to 0.5-1 wt%, further improving the purity of the indigo.

However, not all extraction solvents have a purification effect. The experiments in Table 2 show that no acidic aqueous solution, alkaline aqueous solution or neutral water has any purification effect, while organic solvents can effectively reduce the indirubin content, among which the purification of low-polarity solvents (such as methyl ethyl ketone, cyclohexane) The effect is better, provided that the solvent can dissolve indirubin.

In addition, it can be seen from Experiment 38 in Table 2 that separate extraction, that is, extraction of dyes without hydrolysis, still has the effect of reducing indirubin content and improving indigo purity. However, the improvement in indigo purity and the reduction in indirubin are not as good as hydrolysis first and then Extraction purification step. Example 4 Cotton yarn dyeing test

This experiment compares the dyeing ability of biomass indigo dye purified by the purification method of the embodiment of the present invention and chemically synthesized indigo dye. Prepare the dye mother liquor according to the formula in Table 3. Take 20 g of dye, 16 g of sodium hydroxide (NaOH), and 20 g of insurance powder (Na ₂ S ₂ O ₄ ) into a 1000 ml beaker, and add deionized water to the total weight. 500 g, stir for 2 hours, the solution will appear transparent amber, and its pH and potential value (mV) will be 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 the chemical indigo dye is 88.0% and the indirubin content is 0.31%. **The biomass indigo dye prepared according to the hydrolysis and extraction conditions of Experiment 36 is used here. The indigo concentration is 92.1% and the indirubin content is 92.1%. is 0.5%

It can be seen from Table 3 that under similar indigo concentrations, the chemical indigo dye and the biomass indigo dye of this embodiment have similar pH values and potentials.

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

Finally, a Datacolor Spectro 1000 spectrometer was used to analyze the dye solutions of Experiment 39 (chemical indigo dye) and Experiment 40 (purified biomass indigo dye of the present invention) under the conditions of 26 mm aperture, D65 light source, and 10-degree angle. The coloring strength of the fiber material after coloring with the mother liquor is measured, and the coloring strength is calculated according to the Kubelka-Munk Theory formula. Among them, the fiber material after dyeing with the dye mother liquor of Experiment 39 (chemical indigo dye) was used as a standard sample. The coloring strength measured by pressing and sucking it 1, 3, and 6 times was set as 100, and compared with Experiment 40 (the present invention). The fiber materials after dyeing with the dye liquor mother liquor of Example) are compared. The results are as follows in Table 4.

Table 4 Comparison of coloring strength of indigo dye dyeing samples test project experiment DE* MI** intensity 39 Chemical indigo dye (standard sample) Press and suck 1 time 0 0 100 Pump 3 times 0 0 100 Press and suck 6 times 0 0 100 40 Biomass indigo dye Press and suck 1 time 0.26 0.10 97.65 Pump 3 times 1.39 0.19 110.29 Press and suck 6 times 1.46 0.22 125.94 DE*: color difference MI**: metameric coefficient

After 1-6 times of pressing and sucking, the color difference DE values of the bio-indigo dye of this embodiment and the standard sample are all between 0-2, which means that the color difference between the two cannot be distinguished. The low Metamerism-Index (MI) indicates that the dyed sample has the same color difference under different color temperature light sources and is a high-quality dye. In addition, the coloring strength (97.65) of biomass indigo dye after one press is close to the standard chemical indigo dye (100), and after multiple press tests, the coloring strength (110-125) is 10-10 higher than that of chemical indigo dye. 20%, meaning more dye is attached to the fiber. Therefore, the dyeing effect of the biomass indigo dye processed by the purification method (hydrolysis, filtration, extraction) of this embodiment is better than that of chemical indigo dye. Even if the usage amount during dyeing is reduced by 10 to 20%, it can still reach the same level as chemical indigo dye. Same dyeing effect.

Accordingly, the purification method of biomass indigo dye provided in this embodiment can not only greatly improve the indigo purity of biomass indigo dye, reduce the concentration of indirubin, and reach a level close to that of chemical indigo dye, but can even surpass chemical indigo dye in coloring strength. , can reduce the amount of dye, which is not only environmentally friendly but also reduces production costs.

1: White porcelain funnel 2: Glass conical suction bottle 3:Filter cloth 4:Pump 5: Dehydrator 6:Filter bag 7:Inner tank 8: Fat extraction device 9:Cylinder filter paper

Figure 1 is a flow chart of a biomass indigo dye purification method according to an embodiment of the present invention;

Figure 2 is a schematic diagram of the air extraction filter device;

Figure 3 is a schematic diagram of the dewatering and filtering device;

Figure 4 is a schematic diagram of the extraction device.

Claims (13)

A method for purifying biomass indigo dye, including: (1) Provide biomass indigo dye; (2) Hydrolyze the biogenic indigo dye with a hydrolysis reagent, which is an acidic solution, an alkaline solution or a proteolytic enzyme solution; (3) Purify the hydrolyzed biomass indigo dye by filtration, extraction, or filtration and then extraction; and (4) Drying and purifying the biomass indigo dye. The purification method as described in claim 1, wherein the source of the biomass indigo dye provided in step (1) is a plant extract or a microbial fermentation metabolite. The purification method as described in claim 1, wherein the indigo purity of the biomass indigo dye provided in step (1) is less than about 60%, and the indigo purity of the biomass indigo dye dried in step (4) above about 90% The purification method as described in claim 1, wherein the biomass indigo dye provided in step (1) contains about 5 wt% indirubin, and the indigo of the biomass indigo dye dried in step (4) is The jade red content is about 3 wt% or less. The purification method as described in claim 1, wherein the hydrolysis step of step (2) is performed at room temperature to 100°C. The purification method as described in claim 1, wherein the acidic solution is a 1-18N acidic aqueous solution, the alkaline solution is a 1-18N alkali metal hydroxide aqueous solution or an organic base, and the proteolytic enzyme is a fungal protease, a bacterial protease, a plant protease, Aqueous solution of pepsin or trypsin. The purification method as described in claim 1, wherein in the hydrolysis step of step (2), the added amount of the hydrolysis reagent is 3-7 times that of the biomass indigo dye. The purification method as claimed in claim 1, wherein the filtration method in step (3) is suction filtration or dehydration filtration. The purification method as described in claim 8, wherein the filtration method in step (3) includes passing the hydrolyzed biomass indigo dye 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 according to claim 9, wherein the material of the filter cloth includes polypropylene (PP), polyvinyl alcohol (Vinylon), polyester (polyester) and polyamide (polyamide). The purification method as described in claim 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 claim 11, wherein the organic solvent can dissolve indirubin. The purification method as claimed in claim 11, wherein the organic solvent is alcohol, isopropyl alcohol, acetone, methyl ethyl ketone or cyclohexane.