阅读说明：本技术 一种基于离子液体的黑色素分离提取方法 (Melanin separation and extraction method based on ionic liquid ) 是由 陈朱琦 罗放 赵钦地 姜旺 王训 于 2021-09-24 设计创作，主要内容包括：本发明涉及基于离子液体的黑色素分离提取的方法,属于废弃毛发资源化技术领域。本发明提出使用离子液体与解聚剂对毛发进行解聚处理,然后运用双水相体系一步分离氨基酸、离子液体与黑色素,随后对分相剂中的氨基酸进行萃取操作,并对离子液体、分相剂进行回收处理。实际操作步骤简单,能高效分离出高纯度黑色素,且黑色素颗粒保持原貌,便于后续高端应用；能回收并再利用主要试剂,可以大幅削减生产成本。本发明具有高效、无三废排放、具备极佳的经济可行性等优势。(The invention relates to a melanin separation and extraction method based on ionic liquid, and belongs to the technical field of waste hair recycling. The invention provides a method for depolymerizing hair by using ionic liquid and a depolymerizing agent, then separating amino acid, the ionic liquid and melanin by using a two-aqueous-phase system in one step, then extracting the amino acid in a phase-splitting agent, and recovering the ionic liquid and the phase-splitting agent. The practical operation steps are simple, the high-purity melanin can be efficiently separated, and the original appearance of the melanin particles is kept, so that the subsequent high-end application is facilitated; the main reagent can be recovered and reused, and the production cost can be greatly reduced. The method has the advantages of high efficiency, no three-waste discharge, excellent economic feasibility and the like.)

1. A melanin separation and extraction method based on ionic liquid is characterized by comprising the following steps:

(1) adding ionic liquid into hair, and heating to dissolve hair; adding depolymerizing agent, and heating to depolymerize hair to obtain hair depolymerizing liquid;

(2) adding an aqueous solution of a phase splitting agent into the hair depolymerizing liquid obtained in the step (1), fully and uniformly mixing, and centrifuging to obtain an upper phase, a lower phase and melanin precipitates from top to bottom; the upper phase is an ionic liquid enrichment phase, and the lower phase is a mixture of a phase splitting agent and amino acid; separating out the precipitate in the phase separation system, namely extracting the melanin from the hair to be treated.

2. The method for separating and extracting melanin based on ionic liquid according to claim 1, wherein the lower phase is extracted by using a hydrophobic extractant, and the hydrophobic extractant separates the phase separation agent and the amino acid in the lower phase, namely the keratin-degraded amino acid in the hair is extracted; and the separated phase separating agent can be reused in the step (2).

3. The method for separating and extracting melanin based on ionic liquid according to claim 1 or 2, wherein the ionic liquid obtained from the upper phase can be reused in the step (1).

4. The method for separating and extracting melanin based on an ionic liquid according to claim 1, wherein the ionic liquid is at least one of 1, 3-dibenzylimidazole acetate, 1- (2-naphthylmethyl) -3-methylimidazole acetate, 1-heptyl-3-methylimidazole acetate, 1-ethyl-3-methylimidazole acetate, 1-acetic acid benzyl-3-methylimidazole salt, 1- (cyclohexylmethyl) -3-methylimidazole acetate and 1-butyl-3-methylimidazole chloride salt, preferably at least one of 1-ethyl-3-methylimidazole acetate, 1-acetic acid benzyl-3-methylimidazole salt and 1-butyl-3-methylimidazole chloride salt, more preferably 1-butyl-3-methylimidazolium chloride.

5. The method for separating and extracting melanin based on ionic liquid according to claim 1 or 4, wherein the depolymerizing agent is at least one of nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid, sulfonic acid, salicylic acid and citric acid, preferably at least one of hydrochloric acid, sulfuric acid and phosphoric acid, and further preferably sulfuric acid.

6. The method for separating and extracting melanin based on ionic liquid according to claim 1, wherein the phase-separating agent is at least one of phosphate, sodium hydroxide, potassium hydroxide, tartrate, ethylene diamine tetraacetic acid and dithizone.

7. The method for separating and extracting melanin based on ionic liquid according to claim 2, wherein the hydrophobic extractant is di (2-ethylhexyl) phosphoric acid.

Technical Field

The invention belongs to the technical field of waste hair recycling, and particularly relates to a melanin separation and extraction method based on ionic liquid.

Background

The waste hair is solid waste generated by human beings and animals, and the annual yield of the waste hair reaches more than million tons worldwide. Waste hair contains a large amount of valuable component substances such as keratin and melanin. Keratin is easily hydrolyzed to produce amino acids, which can be applied in various industries. Melanin is also known as a useful biological pigment, and has been used in the fields of surface modification, cell interfacing, biosensing applications, and nanomedicine. However, today's resource recovery processes for hair still have many disadvantages: in industrial processes, amino acids are usually recovered by strong acid hydrolysis, which is a process of hydrolyzing hair at high temperature with strong acid, and which generates a large amount of acid waste liquid, obviously is not environment-friendly, and requires expensive acid-proof equipment. The recovery of melanin from waste hair, especially waste human hair, has only been reported on a laboratory scale: as in the conventional scheme by alkaline Dissolution followed by Acid precipitation (Base-Dissolution and Acid-Isolation), at least 51 purification steps are required and the yield is only 2.2%; the enzymatic hydrolysis process of melanin requires expensive proteinase K and long pretreatment time (usually four days), and these harsh conditions limit the practical application of these processes.

Disclosure of Invention

The invention solves the technical problems of low melanin recovery yield, complex operation, expensive protease, long pretreatment time and the like in the prior art. Aiming at the needs of the existing situation and the shortcomings of the prior art, the invention provides a technical process for melanin targeted extraction based on ionic liquid. The technology can greatly simplify fifty-step purification process which is complicated in the traditional method, greatly improves the feasibility and economic feasibility of industrial application, hardly generates the problem of three wastes because the novel solvent which is the ionic liquid and has low vapor pressure and can be recycled, and is relatively friendly to the environment. The traditional method can destroy the natural structure of the melanin product, the melanin product has keratin impurities, and the technology can produce high-purity melanin and keep the natural morphological structure of the melanin not to be damaged. The technology can produce amino acid while producing melanin, and can realize the maximum utilization of waste resources. In summary, the present technique has great advantages over the prior art.

According to the purpose of the invention, the melanin separation and extraction method based on the ionic liquid comprises the following steps:

(1) adding ionic liquid into hair, and heating to dissolve hair; adding depolymerizing agent, and heating to depolymerize hair to obtain hair depolymerizing liquid;

(2) adding a phase splitting agent into the hair depolymerizing liquid obtained in the step (1), fully and uniformly mixing, and centrifuging to obtain an upper phase, a lower phase and melanin precipitates from top to bottom; the upper phase is an ionic liquid enrichment phase, and the lower phase is a mixture of a phase splitting agent and amino acid; separating out the precipitate in the phase separation system, namely extracting the melanin from the hair to be treated.

Preferably, the lower phase is extracted by using a hydrophobic extracting agent, and the hydrophobic extracting agent separates the phase separating agent and the amino acid in the lower phase, namely the keratin degraded amino acid in the hair is extracted; and the separated phase separating agent can be reused in the step (2).

Preferably, the ionic liquid obtained in the upper phase can be reused in step (1).

Preferably, the ionic liquid is 1, 3-dibenzylimidazole acetate, 1- (2-naphthylmethyl) -3-methylimidazole acetate, 1-heptyl-3-methylimidazole acetate, 1-ethyl-3-methylimidazole acetate, at least one of 1-acetic acid benzyl-3-methylimidazolium salt, 1- (cyclohexylmethyl) -3-methylimidazolium acetate and 1-butyl-3-methylimidazolium chloride salt, preferably at least one of 1-ethyl-3-methylimidazolium acetate, 1-acetic acid benzyl-3-methylimidazolium salt and 1-butyl-3-methylimidazolium chloride salt, and more preferably 1-butyl-3-methylimidazolium chloride salt.

Preferably, the depolymerization agent is at least one of nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid, sulfonic acid, salicylic acid and citric acid, preferably at least one of hydrochloric acid, sulfuric acid and phosphoric acid, and more preferably sulfuric acid.

Preferably, the phase-separating agent is at least one of phosphate, sodium hydroxide, potassium hydroxide, tartrate, EDTA and dithizone.

Preferably, the hydrophobic extractant is di (2-ethylhexyl) phosphoric acid.

Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

(1) the invention provides a novel melanin production technology with industrial potential and practical application value. Compared with the traditional alkali-soluble acid precipitation method which can destroy the natural structure of the melanin product, the melanin product contains keratin impurities, and the technology can produce high-purity melanin and keep the natural morphological structure of the melanin not to be damaged.

(2) The solvent and the ionic liquid used in the invention can accurately destroy and dissolve the hydrogen bonds and the disulfide bonds in the hair keratin without destroying the structure of dissolved melanin. If the melanin is required to be separated from the solution, pure water is required to be added to increase the fluidity of the solution, so that the separation is facilitated. However, after adding pure water, the protein is regenerated and combined with melanin again to cause purification failure, so that the protein is depolymerized and cannot be regenerated by adding a weakly acidic depolymerizing agent, thereby achieving the purpose of separating and purifying the melanin.

(3) The traditional alkali-dissolving acid-precipitating method needs a large amount of purification operation, has extremely low industrialization possibility, can generate a large amount of acid-base waste liquid, and is not environment-friendly. The technical method of the invention does not need to use a large amount of acid-base solution, and can directly separate the melanin after simple operation.

(4) The technical method of the invention can produce amino acid while producing melanin, and can maximize the utilization of hair waste resources.

(5) The technical method can produce high-value melanin granules with natural appearance at low cost, breaks through the limitation of various traditional methods, and has the potential of large-scale application.

Drawings

Fig. 1 is a technical process flow of melanin targeted extraction based on ionic liquid.

FIG. 2 shows the melanin granules (natural granule morphology) of human hair obtained in example 3.

Figure 3 is a uv spectrum characterization of melanin products.

FIG. 4 is a linear relationship of the log of absorbance of melanin product with wavelength.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

A technical process for melanin targeted extraction based on ionic liquid specifically comprises the following steps:

(1) putting the hair and the ionic liquid into a reaction kettle, heating to dissolve the hair, adding a depolymerizing agent after the hair and the ionic liquid are dissolved, and continuing heating until the hair is depolymerized to obtain the hair dissolving liquid. The hair includes but is not limited to animal hair such as human hair, wool, pig hair, etc., and is characterized by containing melanin. Wherein the ionic liquid is at least one of 1, 3-dibenzylimidazole acetate, 1- (2-naphthylmethyl) -3-methylimidazole acetate, 1-heptyl-3-methylimidazole acetate, 1-ethyl-3-methylimidazole acetate, 1-acetic acid benzyl-3-methylimidazole salt, 1- (cyclohexylmethyl) -3-methylimidazole acetate and 1-butyl-3-methylimidazole chloride salt, preferably at least one of 1-ethyl-3-methylimidazolium acetate, 1-acetic acid benzyl-3-methylimidazolium salt and 1-butyl-3-methylimidazolium chloride salt, most preferably 1-butyl-3-methylimidazolium chloride salt. The depolymerizing agent comprises at least one of nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid, sulfonic acid, salicylic acid and citric acid, and is characterized by being capable of depolymerizing keratin macromolecules in a dissolved state into small molecules. Hydrochloric acid, sulfuric acid, phosphoric acid are preferred, and sulfuric acid is most preferred.

(2) And adding a phase separation agent into the hair depolymerizing liquid obtained in the first step, stirring the mixture, centrifuging, and allowing an upper layer, a lower layer and melanin to precipitate. The phase separating agent is composed of at least one of reagents including but not limited to phosphate, sodium hydroxide, potassium hydroxide, tartrate, EDTA, dithizone and the like. It is characterized in that the natural phase separation and delamination phenomenon can be formed with the ionic liquid under a certain temperature condition.

(3) And (3) separating the three-phase mixture obtained in the last step, wherein the upper phase is an ionic liquid enrichment phase, and the ionic liquid enrichment phase can be directly recycled to the step (1) after water is removed through reduced pressure distillation. The lower phase is a mixture of amino acid and phase separating agent, and the precipitate is melanin product.

(4) And (3) extracting the lower phase by using a hydrophobic extractant, and separating the phase separating agent from the amino acid, wherein the purified phase separating agent can be directly recycled to the step (2), and the hydrophobic extractant is di (2-ethylhexyl) phosphoric acid (D2 EHPA).

Example 1

Fig. 1 is a technical process flow of melanin targeted extraction based on ionic liquid.

The method comprises the following steps: a mixture of 0.2g of the washed waste human hair (hair) and 4g of 1-butyl-3-methylimidazolium chloride salt (ionic liquid) was heated in a beaker at 130 c until the waste human hair was completely dissolved. 0.2mL of dilute sulfuric acid (50 wt%) (depolymerization agent) was added to the mixture, and the mixture was heated at 120 ℃ for 1.2 hours.

Step two: adding 20mL of aqueous solution into the mixture, shaking the mixture vigorously for 2min, centrifuging (5000rpm,5min) to obtain melanin product precipitate with yield of 6.02%, and adding 20mL of 0.7g/mL K into the liquid phase₃PO₄The upper phase and the lower phase are separated. The upper layer solution is rich in 1-butyl-3-methylimidazolium chloride, is collected and is directly recycled to the step one after 5 hours of reduced pressure distillation treatment. The lower solution is rich in compound amino acid and phase separating agent, and the lower solution rich in compound amino acid is collected for next extraction.

Step three: extracting the lower phase solution by using kerosene diluted di (2-ethylhexyl) phosphoric acid (0.3-0.9M) (an extracting agent), extracting amino acid into an oil phase, separating a phase separating agent and the amino acid, distilling the phase separating agent under reduced pressure to 20ml, and recycling the phase separating agent to the second step.

Example 2

The method comprises the following steps: a mixture of 1g of washed waste brown wool (hair) and 20g of 1-butyl-3-methylimidazolium chloride salt (ionic liquid) was heated in a beaker at 130 c until the waste human hair was completely dissolved. 1mL of dilute sulfuric acid (50 wt%) (depolymerization agent) was added to the mixture, and the mixture was heated at 120 ℃ for 2.2 hours.

Step two: adding 100mL of aqueous solution into the mixture, shaking the mixture vigorously for 6min, centrifuging at 5000rpm for 10min to obtain melanin product precipitate with yield of 7.24%, and adding 100mL of 0.7g/mL K into the liquid phase₃PO₄The upper phase and the lower phase are separated. The upper layer solution is rich in 1-butyl-3-methylimidazolium chloride, is collected and is directly recycled to the step one after 5 hours of reduced pressure distillation treatment. The lower solution is rich in compound amino acid and phase separating agent, and the lower solution rich in compound amino acid is collected for next extraction.

Step three: extracting the lower phase solution by using kerosene diluted di (2-ethylhexyl) phosphoric acid (0.3-0.9M) (an extracting agent), extracting amino acid into an oil phase, separating a phase separating agent and the amino acid, distilling the phase separating agent under reduced pressure to 100ml, and recycling the phase separating agent to the second step.

Example 3

SEM tests were performed on the basis of example 1, and the test results are shown in fig. 2.

Description of the test: usually, the SEM test can be directly used to observe whether the surface morphology of melanin still maintains the original nanoparticle shape, so as to determine whether the natural morphology structure of melanin is damaged. Granular melanin, which retains its natural morphology, is generally considered an excellent melanin product.

Example 4

UV tests were carried out on the basis of examples 1, 2 (fig. 3) and logarithmic absorbance curves (fig. 4) were made to characterize the melanin.

Description of the test: the purity of melanin is generally determined using UV-Vis adsorption spectroscopy, because of the complex conjugated structure in melanin, there is a peak at 220nm, and pure melanin does not show peaks representing protein impurities at 260nm and 280nm, the higher the purity of melanin, the smoother the curve (fig. 3). Whether the product is melanin can also be generally judged by observing whether the logarithmic value of the ultraviolet absorbance of melanin is linear with the wavelength (fig. 4), and melanin extracted from human hair generally shows a slope of-0.003.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.