CN112898800A

CN112898800A - Method for extracting indigo

Info

Publication number: CN112898800A
Application number: CN202110063213.9A
Authority: CN
Inventors: 高旻天
Original assignee: Shandong Yunqing Biotechnology Co ltd
Current assignee: Shandong Yunqing Biotechnology Co ltd
Priority date: 2021-01-18
Filing date: 2021-01-18
Publication date: 2021-06-04
Anticipated expiration: 2041-01-18
Also published as: CN112898800B

Abstract

The invention discloses an extraction method of indigo, which comprises the following steps: firstly, cleaning and soaking indigo honeysuckle leaves containing indican in water, and separating the leaves after soaking; secondly, adding alkali into the liquid obtained in the first step to adjust the pH value to be alkaline, and introducing nitrogen or carbon dioxide into the liquid under a closed condition; thirdly, continuously stirring the liquid introduced with the nitrogen or the carbon dioxide for more than 1 hour, and adding acid to adjust the pH value to be acidic and settling the indigo; and fourthly, carrying out solid-liquid separation to obtain a precipitate, and drying the precipitate to obtain the indigo. In the extraction method, after alkaline substances are added into the soaked water, gases such as nitrogen, carbon dioxide and the like are introduced to reduce the dissolved oxygen value in the liquid under the alkaline condition, so that the generation of byproducts and the settlement of plant tissues are reduced, and the concentration of the indigo is effectively improved.

Description

Method for extracting indigo

Technical Field

The invention relates to an extraction method of natural plant dye, in particular to an extraction method of indigo.

Background

Indigo is one of the oldest dyes with the largest yield in the world, and is widely applied to industries such as printing and dyeing, food, medicine and the like. Indigo is a secondary metabolite of plants. Indoxyl- β -D-glucoside, an important precursor of indigo, is present in the leaves of blue grass, such as isatis tinctoria, Indigofera tinctoria, and Indigofera tinctoria. When the tissue of the bluegrass leaves is damaged, indoxyl glucoside in vacuole is catalyzed by glucosidase in chloroplast to generate indoxyl, indole ligand is subjected to autoxidation reaction in the air to generate indigo, and meanwhile, the indoxyl is subjected to condensation reaction under alkaline conditions to form the indigo.

The preparation method of indigo mainly comprises plant extraction method and chemical synthesis method. The plant extraction method comprises soaking leaf of blue grass (such as Isatis tinctoria L., Indigofera tinctoria L., Polygonum tinctoria L., etc.) in water, naturally fermenting to obtain indoxyl, adding calx to make water alkaline, dissolving indoxyl in alkaline solution, and allowing ketone type tautomerism to occur to obtain indigo blue. The plant extraction method has the advantages of safety and environmental protection, and has the defects that the concentration of the indigo is not high, and the final concentration of the indigo is 2-3%.

Chinese patent document CN 103881414a (application No. 201410066631.3) discloses a method for extracting indigo from wild trees, which comprises the steps of extracting indigo mud from wild tree branches and leaves, and purifying the indigo mud to obtain indigo: adding distilled water into indigo sludge, stirring uniformly, slowly adding hydrochloric acid under stirring, stopping stirring when bubbles do not appear, and heating in water bath to 100 ℃ for 1 hour; then extracting, pumping out the water, adding distilled water, stirring, washing with water to neutral pH-7, pumping out the water, leaving a precipitate, adjusting the pH of the added distilled water to be pH-9 by using 5% sodium hydroxide, pouring into a container for containing the precipitate, stirring uniformly, heating in a water bath for boiling for 1 hour again, pumping and filtering, washing with water to neutral pH-7, pumping out the water to obtain a purified sample, drying the sample in an oven at 60 ℃ for 4 hours, crushing and sieving with a 100-mesh sieve to obtain the purified sample.

Chinese patent document CN 107365512a (application No. 201610318311.1) discloses a method for extracting natural indigo dye from isatis root, the extraction method is as follows: (1) materials: adopting stems, branches and leaves of overground parts of the isatis root plants which grow for one or two years as raw materials; (2) cutting radix isatidis: after the isatis root grows for 5-7 months, when the plant branches are full, fresh and tender stems, branches and leaves of the isatis root are cut from the part, which is about 10 cm away from the ground, and weeds and impurities are removed, so that the quality of the natural indigo dye is improved; (3) soaking: throwing the cut fresh and tender stems, branches and leaves of the isatis root into a large water bucket or a water pool for soaking and fermenting, wherein the fermentation time is about 8 days, so that the cyanin is fully dissolved from the histiocyte of the plant, the summer time is short, and the autumn and winter days are long; (4) adding lime: adding lime powder into a large water bucket or a water tank container filled with the stems, branches and leaves of the isatis root to ensure that indigo substances are fully exuded, and simultaneously, the stems, branches and leaves of the isatis root plants soaked and fermented are not rotten; (5) fishing out the stems, branches and leaves of the isatis root: fishing out and wringing the branches and leaves of the stems of the isatis roots after soaking and fully oozing the indigo substances; (6) adding lime water, stirring and stirring: putting a small amount of lime water into the soaking solution obtained by fishing out the stems, branches and leaves of the isatis root, pouring the soaking solution out with a water ladle, so that the soaking solution is stirred and stirred, and continuously and repeatedly carried out, and the capacity of decomposing the indigotin is enhanced, wherein the time is about 1-2 hours; (7) standing: stirring or stirring until indigo blue colloid appears, standing the soaking solution for 4-5 days; (8) filtering clear water: after standing treatment, the indigo substance is decomposed and subsided by lime to be dark blue colloid, namely clear water is poured out, and then the indigo substance is stood for 1 to 2 days, and then the filtered clear water is poured out to obtain the indigo colloid; (9) and (3) finished product: the indigo blue gelatinous substance-pasty indigo mud obtained after filtering out clear water is an indigo blue natural dye product, and the indigo blue gelatinous substance-pasty indigo mud is dried in the sun or in the oven and is ground into powder to obtain a finished product.

Disclosure of Invention

The invention aims to provide a method for extracting high-purity indigo.

The technical scheme for realizing the aim of the invention is an indigo extraction method, which comprises the following steps:

firstly, washing the indigo leaf containing the indican, putting the indigo leaf into water for soaking, and separating the leaves after soaking.

Secondly, adding alkali into the liquid obtained in the first step to adjust the pH value to be alkaline, introducing nitrogen or carbon dioxide into the liquid under a closed condition, wherein the dissolved oxygen value in the liquid is less than 20% of the saturated dissolved oxygen value at the corresponding temperature.

Thirdly, continuously stirring the liquid introduced with the nitrogen or the carbon dioxide for more than 1 hour, and adding acid to adjust the pH value to be acidic and settling the indigo.

And fourthly, carrying out solid-liquid separation to obtain a precipitate, and drying the precipitate to obtain the indigo.

In the first step, adding biological enzyme into water, wherein 0.1-2 g of biological enzyme is added into every 1L of water; the biological enzyme is one or a composition of more than one of glucose oxidase, chymotrypsin or trypsin.

The soaking time is 0.5-12 h after adding the biological enzyme.

And secondly, introducing nitrogen or carbon dioxide into the liquid for 1 to 3 hours.

And secondly, adding alkali to adjust the pH to 9-13.

And in the third step, after the aeration, continuously stirring the liquid into which the nitrogen or the carbon dioxide is introduced for 1 to 5 hours.

And in the third step, adding acid to adjust the pH value to 1-5.

The method comprises the following steps:

the invention has the positive effects that:

(1) in the extraction method, after alkaline substances are added into the soaked water, gases such as nitrogen, carbon dioxide and the like are introduced to reduce the dissolved oxygen value in the liquid under the alkaline condition, so that the generation of byproducts and the settlement of plant tissues are reduced, and the concentration of the indigo is effectively improved.

(2) The plant extraction method has simple process and lower cost, and improves the purity of the indigo on the premise of not increasing the production cost.

Drawings

FIG. 1 is a graph showing a comparison of the purity of indigo obtained in example 1 and comparative example 1.

FIG. 2 is a graph showing the relationship between the purity of indigo and the nitrogen and air supply times.

FIG. 3 is a graph showing the dyeing effect of indigo obtained by different processes in the application examples.

Detailed Description

The present invention is described in detail below by way of examples, it should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and those skilled in the art can make some insubstantial modifications and adaptations of the present invention based on the above-described disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

(example 1)

The extraction method of indigo of the embodiment comprises the following steps:

firstly, 100g of indigo-containing blue grass leaves (Polygonum tinctorium leaves in this example) are washed and put into 1L of water, left to stand at room temperature (15 ℃ C. -35 ℃ C., 15 ℃ C. in this example) for 2-3 days (2 days in this example), and then the leaves are separated by filtration.

The indigo leaf may be Isatis tinctoria, Indigofera tinctoria, or Indigofera tinctoria.

And secondly, adding sodium hydroxide into the liquid obtained by separation after the soaking fermentation in the step I, and adjusting the pH value of the liquid to 10. And introducing nitrogen into the alkaline liquid for 2 hours under a sealed condition, and keeping stirring during the introduction. At this time, the dissolved oxygen value in the liquid is 20% or less of the saturated dissolved oxygen value at the corresponding temperature, and in this example, the dissolved oxygen value is controlled to 5% of the saturated dissolved oxygen value at the corresponding temperature.

And thirdly, continuously stirring the liquid obtained in the step II after the nitrogen is introduced for 3 hours, and adding sulfuric acid to adjust the pH value of the liquid to be 1 after the stirring is finished to settle the indigo.

Fourthly, after natural sedimentation, carrying out filter pressing collection to obtain a precipitate, and drying the precipitate to obtain the indigo.

(example 2)

The extraction of indigo according to this example is otherwise the same as in example 1, except that:

in the first step, 100g of Isatis tinctoria leaves were washed and put into 1L of water, 1g of trypsin was added to the water, and the mixture was immersed for 11 hours, followed by filtration to separate the leaves.

In the second step, sodium hydroxide is added into the liquid obtained after hydrolysis and separation in the first step, and the pH value is adjusted and separated to 13. And introducing carbon dioxide into the alkaline liquid for 1.5h under a sealed condition, and keeping stirring during the introducing process, wherein the dissolved oxygen value in the liquid is 12% of the saturated dissolved oxygen value at the corresponding temperature.

And step three, continuously stirring the liquid introduced with the carbon dioxide for 1 hour, and continuously stirring, adding sulfuric acid into the liquid to adjust the pH value of the liquid to be 3.

And fourthly, naturally settling, performing suction filtration to obtain a precipitate, and drying the precipitate to obtain the indigo.

(example 3)

The extraction process of indigo in this example is otherwise the same as in example 2, except that:

in the step I, 200g of the leaves of the Indigofera tinctoria are cleaned and put into 1L of water, and 2g of glucose oxidase is added to soak the leaves for 2 hours.

In the second step, sodium hydroxide is added into the liquid obtained after hydrolysis and separation in the first step, and the pH value is adjusted and separated to be 11. Nitrogen gas was introduced into the basic liquid under sealed conditions for 1 hour.

And step three, continuously stirring the liquid after the nitrogen is introduced for 4 hours, and adding sulfuric acid to adjust the pH value of the liquid to 1.

(example 4)

The extraction process of indigo in this example is otherwise the same as in example 3, except that:

and step II, introducing nitrogen into the alkaline liquid for 80 minutes under a sealed condition.

(example 5)

and step II, introducing nitrogen into the alkaline liquid for 2 hours under a sealed condition.

The purity of the indigo prepared in examples 3, 4 and 5 was measured by liquid chromatography in the same manner as in example 1, and the results are shown in FIG. 2.

In addition, the purity of indigo was measured by performing a control experiment in which nitrogen was introduced into examples 1, 4 and 5 for 1 hour, 80 minutes and 2 hours, and the results are shown in FIG. 2.

As can be seen from fig. 2, in the case of nitrogen gas injection, the indigo purity increased gradually with increasing time of nitrogen gas injection. Whereas the indigo purity decreases gradually with increasing time after 1 hour with the introduction of air.

Comparative example 1

The extraction method of indigo of this comparative example comprises the following steps:

firstly, 100g of Polygonum tinctorium leaves are washed and put into 1L of water, and are placed for 2 days at 15 ℃, and then the leaves are filtered and separated.

And secondly, adding sodium hydroxide into the liquid obtained by separation after the soaking fermentation in the step I, and adjusting the pH value of the liquid to 10. Air was introduced into the basic liquid under a closed condition for 2 hours while keeping stirring during the introduction.

And thirdly, continuously stirring the liquid obtained in the step II after air is introduced for 3 hours, and adding sulfuric acid to adjust the pH value of the liquid to be 1 after stirring to settle the indigo.

Fourthly, after natural sedimentation, collecting the obtained precipitate and drying the precipitate to obtain the indigo.

The purity of indigo obtained in example 1 and comparative example 1 was checked by liquid chromatography.

The chromatographic conditions are as follows: the separation column is a C18 column, the mobile phase is acetonitrile-0.05% phosphoric acid, and gradient elution is carried out. The detection wavelength is 300 nm, the column temperature is 30 ℃, and the sample injection amount is 20 ul.

The results of the measurements are shown in FIG. 1, in which the purity of indigo is 24% in the case of comparative example 1 with air, and 64% in the case of example 1 with nitrogen. The result shows that in the oxygen-free environment, the leaf tissue and indoxyl are not easily oxidized to generate precipitate, and the purity of the indigo is greatly improved.

(Experimental example, indigo dyeing)

The experimental method comprises the following steps:

dye: 0.01g of indigo dye is subjected to ethylation by 5uL, 20uL of liquid alkali (1: 3), 250uL of H2O at 60 ℃ and 0.008g of sodium hydrosulfite are mixed uniformly to prepare the dye.

There were 3 samples of the indigo dye, sample No. 1 was the indigo prepared in comparative example 1 by passing air, sample No. 2 was the indigo prepared in example 1 by passing nitrogen, and sample No. 3 was the indian indigo.

Dyeing: adding 26.8 uL H2O and 270uL dye liquor into 0.45g of fabric, adding 0.134g of caustic soda and 0.134g of sodium hydrosulfite, dyeing for 20min, and drying.

The staining results were as follows: the left panel shows the dyeing results of indigo prepared by aeration in comparative example 1, the middle panel shows the dyeing results of indigo prepared by aeration in example 1 with nitrogen, and the right panel shows the dyeing results of indian indigo. As shown in fig. 3, the indigo prepared by air-blowing was greenish in color after dyeing, indicating that the indigo contained a large amount of impurities. Whereas, after dyeing with indigo prepared by nitrogen, the color of the cloth was blue, without other mottling, similar to that of indian indigo, but darker.

Claims

1. The extraction method of indigo is characterized by comprising the following steps:

firstly, cleaning and soaking indigo honeysuckle leaves containing indican in water, and separating the leaves after soaking;

secondly, adding alkali into the liquid obtained in the first step to adjust the pH value to be alkaline, introducing nitrogen or carbon dioxide into the liquid under a closed condition, wherein the dissolved oxygen value in the liquid is less than 20% of the saturated dissolved oxygen value at the corresponding temperature;

thirdly, continuously stirring the liquid introduced with the nitrogen or the carbon dioxide for more than 1 hour, and adding acid to adjust the pH value to be acidic and settling the indigo;

2. The method for extracting indigo according to claim 1, wherein: adding biological enzyme into water, wherein 0.1-2 g of biological enzyme is added into every 1L of water; the biological enzyme is one or a composition of more than one of glucose oxidase, chymotrypsin or trypsin.

3. The method for extracting indigo according to claim 2, wherein: adding biological enzyme and soaking for 0.5-12 hr.

4. The method for extracting indigo according to claim 1, wherein: and secondly, introducing nitrogen or carbon dioxide into the liquid for 1 to 3 hours.

5. The method for extracting indigo according to claim 1, wherein: and step two, adding alkali to adjust the pH value to 9-13.

6. The method for extracting indigo according to claim 1, wherein: and in the third step, after the aeration, continuously stirring the liquid into which the nitrogen or the carbon dioxide is introduced for 1 to 5 hours.

7. The method for extracting indigo according to claim 1, wherein: and step three, adding acid to adjust the pH value to 1-5.