CN108048954B

CN108048954B - Method for directly preparing carrageenan fibers from red algae extract

Info

Publication number: CN108048954B
Application number: CN201711386375.6A
Authority: CN
Inventors: 薛志欣; 夏延致
Original assignee: Qingdao University
Current assignee: Qingdao University
Priority date: 2017-12-20
Filing date: 2017-12-20
Publication date: 2020-07-03
Anticipated expiration: 2037-12-20
Also published as: CN108048954A

Abstract

The invention discloses a method for directly preparing carrageenan fibers from red algae extract, which comprises the following steps: (1) removing impurities from fresh red algae, washing with water, cutting into small pieces or soaking dry algae in deionized water for more than 24 hours; (2) adding 5-10wt% NaOH solution 10-20 times of the weight of the alga into the treated red alga, heating to 50-80 deg.C, and treating for 0.5-2 hr; (3) taking out the red algae after alkali pretreatment, adding 2-5 times of water, heating and extracting at 85-100 deg.C for 1-4h, and adding NaOH to make the extract reach 5-15 wt%; (4) filtering the above extract to obtain extractive solution; (5) pouring the extracting solution into a spinning kettle, defoaming, feeding into a spinning nozzle, and performing wet spinning by using a 2-15% coagulating bath to prepare carrageenan fibers; (6) the nascent fiber is stretched, washed by water, dehydrated by 95% ethanol and finally dried. The method has the advantages of simple process, energy conservation and consumption reduction, reduces the production flow, and realizes the production process of the carrageenan fibers from the seaweed raw material to the carrageenan fibers.

Description

Method for directly preparing carrageenan fibers from red algae extract

Technical Field

The invention relates to a method for preparing carrageenan fibers, in particular to a method for directly preparing carrageenan fibers from red algae extract.

Background

Carrageenan is a natural linear sulfated polysaccharide extracted from red algae, and carrageenan solution is in a gel state incapable of flowing at room temperature, so traditionally carrageenan is mainly applied in the fields of food, cosmetics, medicines and the like in the forms of a stabilizer, a thickening agent, a gelling agent and the like.

In recent years, with the rapid rise of alginate fibers, carrageenan linear molecules similar to the structure of sodium alginate are also researched and researched in the aspect of fiber forming. However, because of the gel structure of the carrageenan solution, the carrageenan solution needs to be converted into a flowing solution state to carry out solution spinning. The method uses alkali solution as solvent, and can dissolve carrageenin at normal temperature, and spin at normal temperature, and the obtained carrageenin fiber has bright color, uniform fineness and higher strength, and opens up a simple and feasible way for the industrial production of carrageenin.

However, the preparation method of carrageenan fiber still adopts hot water extraction of carrageenan powder (i.e. the seaweed is purified, extracted with hot water, filtered and dried to obtain carrageenan powder), and then the carrageenan powder is dissolved and wet spinning (i.e. the carrageenan powder is dissolved in hot water or alkali to prepare carrageenan solution, and then the carrageenan fiber is formed through coagulation bath) to prepare the fiber. The extraction liquid obtained by extracting the carrageenan under the conventional condition is in a gel state at room temperature, and wet spinning cannot be carried out, so that the carrageenan gel needs to be freeze-dried into powder, and the carrageenan powder is re-dissolved into a solution in the spinning process. The process flow needs precipitation, drying and redissolution, the process is complex, and the consumption of water resources, ethanol, energy and the like is excessive.

Disclosure of Invention

In order to solve the problems, the invention aims to provide a method for directly preparing carrageenan fibers from a red algae extracting solution, wherein the extracting solution is directly converted into a spinning solution without powder in the carrageenan fiber preparation process, so that the process flow is greatly shortened, the water and energy consumption is reduced, the integrated flow from seaweed to the carrageenan spinning solution and then to the carrageenan fibers can be realized under the conditions of low energy consumption and low water consumption, the conversion of the seaweed fiber industry to more environment-friendly type and resource-saving type is realized, the product price is further reduced, and the product competitiveness of the seaweed fibers is improved.

According to the method, the extracting solution obtained in the carrageenan extracting process is added with NaOH to destroy the gel structure of the carrageenan solution at room temperature, so that the extracting solution can be directly converted into spinning solution without precipitation and drying into powder, the carrageenan solution is ensured to be in a flowing state at room temperature, and the preparation process flow is greatly shortened.

The specific technical scheme of the invention comprises the following steps: seaweed cleaning, alkali pretreatment, extraction, filtration, wet spinning, fiber drying and the like:

(1) cleaning: removing impurities from fresh red algae, washing with water, cutting into small pieces or soaking dry algae in deionized water for more than 24 hours;

(2) alkali pretreatment: adding 5-10wt% NaOH solution 10-20 times of the weight of the alga into the treated red alga, heating to 50-80 deg.C, and treating for 0.5-2 hr;

(3) extraction: taking out the red algae after alkali pretreatment, adding 2-5 times of water, heating and extracting at 85-100 deg.C for 1-4h, and adding NaOH to make the extract reach 5-15 wt%;

(4) and (3) filtering: filtering the above extract to obtain extractive solution;

(5) and (3) wet spinning: pouring the extracting solution into a spinning kettle, defoaming, feeding into a spinning nozzle, and performing wet spinning by using a 2-15% coagulating bath to prepare carrageenan fibers;

(6) and (3) drying the fiber: the nascent fiber is stretched, washed by water, dehydrated by 95% ethanol and finally dried.

The red algae is red algae of Carrageenan genus, including carrageen, Salicomia Herbacea or Eucheuma Gelatinosum.

In the step (3), the red algae after alkali pretreatment can also be directly added into 2-5 times of 5-15wt% NaOH solution and heated and extracted for 1-4h at 85-100 ℃.

And the filtering in the step (4) is filtering by using 200-mesh gauze.

The step (5) of solidifying the bath further comprises a stretching bath stage.

The coagulating bath and the drawing bath contain monovalent K⁺Or divalent Ba²⁺、Cu²⁺、Zn²⁺、Ni²⁺、Ca²⁺A solution of metal ions.

The method of the invention may further comprise the step of cross-linking the fibres: and replacing the drawing bath of the wet spinning with ethanol, and adding a cross-linking agent into the ethanol to prepare the cross-linked carrageenan fibers.

The cross-linking agent is epichlorohydrin or aldehyde, dialdehyde or acid anhydride.

Compared with the prior art for preparing the carrageenan fibers, the invention has the following advantages:

according to the invention, the carrageenan fibers are directly prepared from the red algae extract, so that the process flow is greatly shortened, the water and energy consumption is reduced, the integrated flow from the algae to the carrageenan spinning solution and then to the carrageenan fibers is realized under the low energy consumption and low water consumption states, the conversion of the alginate fiber industry to more environment-friendly type and resource-saving type is realized, the product price is further reduced, and the product competitiveness of the alginate fibers is improved. And the strength of the fiber can be improved in an on-line crosslinking mode by adding a crosslinking agent into a drawing bath in the spinning process, and meanwhile, the operation steps are not increased.

The method has the advantages of simple process, energy conservation and consumption reduction, reduces the production flow, and realizes the production process of the carrageenan fibers from the seaweed raw material to the carrageenan fibers.

Drawings

Figure 1 is a schematic of a process scheme for the preparation of carrageenan fiber using conventional methods.

Figure 2 is a process scheme for the preparation of carrageenan fibers according to the present invention.

Detailed Description

The present invention will be described in detail below with reference to specific examples, but the present invention is not limited to only the following examples. All such modifications and variations are intended to be included herein within the scope of this disclosure and the appended claims.

Example 1:

cutting 100g of cleaned fresh carrageen into small pieces of about 1cm, adding 1000ml of 6% NaOH solution, heating in water bath to adjust the temperature to 70 ℃, and pretreating for 1 h. Taking out the pretreated red algae, adding 200ml of 8% NaOH solution, heating in water bath at 95 deg.C for 2 hr, and filtering the extractive solution containing impurities with 2 layers of 200 mesh gauze to obtain extractive solution. Pouring the extracting solution into a spinning kettle, defoaming, feeding into a spinning nozzle, and adding 15% BaCl₂The solution is used as a coagulating bath, carrageenan fibers are prepared by wet spinning, the nascent fibers are stretched and washed by water, then dehydrated by 95 percent ethanol, and finally the carrageenan fibers are dried in a ventilated place.

Example 2:

taking 70g of cleaned fresh salad, cutting into pieces, adding 1000ml of 6% NaOH solution, heating in water bath, adjusting the temperature to 60 ℃, and pretreating for 2 h. Adding 210ml 10% NaOH into pretreated red algae, heating in water bath at 90 deg.C for 2.5 hr, and filtering with 2 layers of 200 mesh gauze to obtain extractive solution. Pouring the extracting solution into a spinning kettle, defoaming, feeding into a spinning nozzle, and taking a 7% KCl solution as a solvent7% CaCl as coagulation bath₂The solution is used as a drawing bath, carrageenan fibers are prepared by wet spinning, the nascent fibers are drawn, washed by water, dehydrated by 95 percent ethanol, and finally dried in a ventilated place.

Example 3:

taking 8.5g of cleaned dry eucheuma, cutting into pieces, soaking in 1000ml of deionized water for 24 hours, taking out, adding 1000ml of 10% NaOH solution, heating in water bath, adjusting the temperature to 80 ℃, pretreating for 0.5 hour, washing with water, adding 300ml of deionized water, heating in water bath at 85 ℃, extracting for 3 hours, adding 2.4g of NaOH into the extract while the extract is hot, stirring uniformly, and filtering the extracted extract containing impurities by using 2 layers of 200-mesh gauze to obtain the extract. Pouring the extracting solution into a spinning kettle, defoaming, feeding into a spinning nozzle, and adding 10% of CuCl₂The solution is used as a coagulating bath, carrageenan fibers are prepared by wet spinning, the nascent fibers are stretched and washed by water, then dehydrated by 95 percent ethanol, and finally the carrageenan fibers are dried in a ventilated place.

Example 4:

taking 100g of cleaned fresh eucheuma, cutting into pieces, adding 1000ml of 8% NaOH solution, heating in water bath to adjust the temperature to 60 ℃, pretreating for 1h, cleaning with water, adding 400ml of deionized water, heating in water bath at 90 ℃ for extracting for 3h, adding 3.2g of NaOH into the extract while the extract is hot, stirring uniformly, and filtering the extract containing impurities after extraction with 2 layers of 200-mesh gauze to obtain an extracting solution. Pouring the extracting solution into a spinning kettle, defoaming, feeding into a spinning nozzle, and adding 5% of BaCl₂The solution is used as a coagulating bath, a drawing bath is epichlorohydrin and ethanol (1: 20, V/V), the carrageenan fibers are prepared by wet spinning, the nascent fibers are drawn and washed by water, then dehydrated by 95 percent ethanol, and finally the carrageenan fibers are dried in a ventilated place.

Comparative example 1:

taking 21g of iota-carrageenan powder, adding 300ml of 8% NaOH to prepare 7% carrageenan solution, pouring the carrageenan solution into a spinning kettle, defoaming, feeding the carrageenan solution into a spinning nozzle, and adding 10% BaCl₂The solution is used as a coagulating bath, carrageenan fibers are prepared by wet spinning, the nascent fibers are stretched and washed by water, then dehydrated by 95 percent ethanol, and finally the carrageenan fibers are dried in a ventilated place.

The mechanical properties of the carrageenan fibers obtained in examples 1, 2, 3, 4 and comparative example 1 were measured and the results are shown in table 1.

TABLE 1 tensile strength of carrageenan fibers prepared by wet spinning in dry state

Fiber sample	Strength (cN/dtex)
		Example 1	1.65
Example 2	1.58
		Example 3	1.61
Example 4	1.76
		Comparative example 1	1.63

As can be seen from table 1, the carrageenan fibers directly spun from the spinning solution are not much different from those prepared in the conventional manner in strength, and the strength of the carrageenan fibers can be improved by crosslinking.

Claims

1. A method for directly preparing carrageenan fibers from red algae extract is characterized by comprising the following steps:

(1) cleaning: removing impurities from fresh red algae, washing with water, cutting into small pieces or soaking dry red algae in deionized water for more than 24 hours;

2. The method of claim 1, wherein the red algae is carrageenin red algae, including carrageenin, hypnea or eucheuma.

3. The method of claim 1, wherein the step (3) is replaced by directly adding 2-5 times of 5-15wt% NaOH solution into the red algae after alkali pretreatment, and extracting at 85-100 deg.C for 1-4 h.

4. The method according to claim 1, wherein the filtration in the step (4) is a filtration using 200 mesh gauze.

5. The method of claim 1, wherein the coagulation bath of step (5) is followed by a draw bath stage.

6. The method of claim 5, wherein the coagulation bath and the draw bath comprise a monovalent K⁺Or divalent Ba² ⁺、Cu²⁺、Zn²⁺、Ni²⁺、Ca²⁺A solution of metal ions.

7. The method of claim 6, further comprising the step of cross-linking the fibers by: and replacing the drawing bath of the wet spinning with ethanol, and adding a cross-linking agent into the ethanol to prepare the cross-linked carrageenan fibers.

8. The process according to claim 7, characterized in that the crosslinking agent is epichlorohydrin or an aldehyde, dialdehyde, anhydride.