CN113304732B - A kind of porous composite material, preparation method and application thereof - Google Patents

Abstract

The invention relates to a porous composite material, a preparation method and its application. The porous composite material contains keratin, silk fibroin and a brominated quaternary ammonium salt cationic surfactant. After adding keratin to the silk fibroin solution, adding Brominated quaternary ammonium cationic surfactant, obtained by injection molding and freeze-drying. The porous composite material prepared by the present invention through rapid gel technology and freeze-drying treatment has the advantages of high porosity, large specific surface area, excellent adsorption performance and the like.

Description

A kind of porous composite material, preparation method and application thereof

technical field

The invention relates to the field of functional materials, in particular to a porous composite material, a preparation method and an application thereof.

Background technique

With the development of social economy and industry, more and more industrial wastewater is produced. A lot of industrial wastewater contains dyes or heavy metal ions that are not easy to degrade, especially dye wastewater has a certain degree of toxicity, and the composition is mixed and the content of organic pollutants is high. If it is discharged into the water body and flows into the ecosystem, it will be gradually enriched by aquatic organisms and eventually endanger the environment. human health.

At present, the adsorption method is mostly used in practice, either through electrostatic interaction (the interaction between positively charged metal ions and negatively charged substrates), or through integration (the matrix provides lone pair electrons to form coordination with metal ions). bit covalent key). Commonly used adsorbents include activated carbon, bentonite, zeolite, and biosorbents. Among them, biosorption has the advantages of rich sources of adsorbents, many varieties, low cost, large adsorption capacity, and fast speed. It can make up for the defects of traditional treatment methods and has been widely accepted. focus on.

CN106279749A discloses a method for preparing a composite sponge of alginate and silk fibroin. The mixed solution of sodium alginate and silk fibroin is mechanically stirred and then directly freeze-dried, which easily leads to uneven distribution of sodium alginate and silk fibroin in the composite sponge; CN110669247A discloses a preparation method of attapulgite-based silk fibroin sodium alginate composite airgel, but the gelation process is long, and it is easy to cause delamination of the two materials in the composite.

The mixture of keratin and silk fibroin can make full use of the good adsorption properties of keratin and the good mechanical properties of silk fibroin, making it possible for the composite material to be applied to actual production and life. However, only relying on simple mechanical stirring, keratin and silk fibroin solution are prone to delamination after mixing, which is not conducive to the improvement of the mechanical properties of composite materials. Therefore, there is still a need for an adsorbent material that is easy to produce, has a short gel time, and has a uniform structure.

Contents of the invention

In order to solve the above technical problems, the present invention provides a porous composite material, which extracts water-insoluble keratin and mixes it evenly with silk fibroin, and adds an appropriate amount of brominated quaternary ammonium salt cationic surfactant to the mixed solution to realize rapid coagulation. glue, and fix keratin and silk fibroin in the mixed solution to form a porous keratin/silk fibroin composite.

A porous composite material of the present invention contains keratin, silk fibroin and brominated quaternary ammonium salt cationic surfactant, after adding keratin to the silk fibroin solution, adding brominated quaternary ammonium salt cationic surfactant obtained by injection molding and freeze-drying.

In the present invention, keratin is added to the silk fibroin solution, and the silk fibroin interacts with the carboxyl and amide groups on the keratin molecule to promote the transformation of the silk fibroin from an amorphous structure to a β-sheet structure, forming a keratin The network structure formed by the mixed β-sheet crystals of silk fibroin is conducive to the formation of gel and has a uniform structure. At the same time, the increase of silk fibroin β-sheet structure exposes more hydrophobic segments of silk fibroin molecules, which strengthens the interaction between the hydrophobic segments of brominated quaternary ammonium salt cationic surfactants and the molecular chains of silk fibroin as well as the interaction between silk fibroin molecules. The hydrophobic association between the molecular chains greatly increases the gel speed, so that the rapid gel effect can be achieved only by adding a low concentration of surfactants.

Further, keratin is water-insoluble keratin. The purpose is to increase the water solubility resistance of the composite material, prevent the loss of keratin, and improve the reusability of the composite material.

Further, the mass ratio of keratin, silk fibroin and brominated quaternary ammonium salt cationic surfactant is 8-12:6-22:1-5.

Further, the brominated quaternary ammonium salt cationic surfactant is selected from cetyltrimethylammonium bromide (CTAB), dedecyltrimethylammonium bromide (DETAB), dodecyltrimethylammonium bromide One or more of trimethyl ammonium bromide (DTAB) and octadecyltrimethylammonium bromide (STAB).

The present invention also claims to protect the application of the above-mentioned porous composite material in biosorption.

The preparation method of the porous composite material of the present invention comprises the following steps:

(1) Put animal hair in a deep eutectic solvent, add water, oscillate and heat, filter, obtain a mixed solution of water-soluble keratin and water-insoluble keratin after dialysis, precipitate, suck out the supernatant, and remove the lower layer of keratin suspension liquid, wherein the concentration of the keratin suspension is 2-3wt%;

dissolving the degummed silk, oscillating and heating, and dialysis to obtain a silk fibroin solution, wherein the concentration of the silk fibroin solution is 5-9 wt%;

(2) Mix the keratin suspension in step (1) with the silk fibroin solution at a mass ratio of 3:1-2 to obtain a keratin/silk fibroin mixed solution, add brominated quaternary ammonium salt cationic surfactant aqueous solution , standing after injection molding to obtain keratin/silk fibroin hydrogel, wherein the concentration of the brominated quaternary ammonium cationic surfactant aqueous solution is 2-8wt%, and the brominated quaternary ammonium cationic surfactant aqueous solution and The mass ratio of keratin/silk fibroin mixed solution is 1:5-10;

(3) freeze-drying the keratin/silk fibroin hydrogel in step (2) to obtain the above-mentioned porous composite material.

Further, in step (1), the animal hair includes various animal hairs such as chicken feather, duck feather, goose feather, wool, rabbit hair, and human hair.

Further, in step (1), the silk fibroin extraction solution is selected from one of lithium bromide, calcium chloride-ethanol-water ternary solvent and deep eutectic solvent. In the solvent, the combination of silk fibroin and water gradually strengthens to expand slowly, and then gradually breaks into sheets, the crystal structure is destroyed, silk fibroin changes from β-sheets to random coils, and silk fibroin is dissolved.

Further, the concentration of lithium bromide is 9-10 mol/L, preferably 9.5 mol/L.

Further, the deep eutectic solvent is choline chloride and oxalic acid with a mass ratio of 1:2. Different combinations of hydrogen acceptors and hydrogen donors in the deep eutectic solvent will lead to great differences in the melting point and solubility of the deep eutectic solvent. The keratin extraction temperature of 70-90°C in the present invention will not lead to changes in the molecular weight of keratin. A sharp drop can avoid a lot of energy consumption.

Further, in step (1), shake at 70-90° C. for 5-7 hours during keratin extraction.

Further, in step (1), when the silk fibroin is extracted, shake at 40-60° C. for 0.5-1 h.

Further, in step (1), the molecular weight cut-off of the dialysis bag is 1-3kDa.

Further, in step (2), the gel velocity of the composite solution can be changed by adjusting the concentration of CTAB, and the higher the concentration, the faster the gel velocity, and obtain composite porous materials with different distribution states of keratin and silk fibroin, thereby controlling Pore structure of porous materials.

Further, in step (2), let stand for 10-300min.

Further, in step (3), freeze-drying is carried out at -40 to -80°C. A composite material with a large pore structure is prepared by freeze-drying, which further increases the specific surface area of the material, fully exposes the adsorption sites in keratin and silk fibroin, and makes it have good adsorption capacity.

By means of the above solution, the present invention has at least the following advantages:

(1) Using natural keratin and silk fibroin, the porous composite material prepared by rapid gel technology and freeze-drying treatment has the characteristics of high porosity, large specific surface area, excellent adsorption performance, and pure natural pollution-free. As protein polymers, keratin and silk fibroin are composed of a large number of different amino acids and contain abundant active groups, such as amino, carboxyl, and hydroxyl groups. These active groups can provide sufficient adsorption sites for the adsorption of dyes and ensure the adsorption performance of the composite material, and the keratin after adsorbing heavy metal ions can be desorbed under acidic conditions, which is convenient for repeated use, and has good applications in the fields of printing and dyeing wastewater treatment. application prospects.

(2) The present invention can realize rapid gelation, so that keratin and silk fibroin can be quickly locked after being evenly dispersed with each other, and delamination can be avoided.

The above description is only an overview of the technical solutions of the present invention. In order to understand the technical means of the present invention more clearly and implement them according to the contents of the description, the preferred embodiments of the present invention are described below with detailed drawings.

Description of drawings

In order to make the content of the present invention more clearly understood, the present invention will be further described in detail below according to the specific embodiments of the present invention and in conjunction with the accompanying drawings.

Fig. 1 is the physical picture and the scanning electron microscope picture of the keratin/silk fibroin composite porous material prepared in embodiment 1;

Fig. 2 is the physical picture and the scanning electron microscope picture of the keratin/silk fibroin composite porous material prepared in embodiment 2;

Fig. 3 is the physical picture and the scanning electron microscope picture of the keratin/silk fibroin composite porous material prepared in embodiment 3;

Fig. 4 is the physical picture and the scanning electron micrograph of the keratin/silk fibroin composite porous material prepared in embodiment 4;

Fig. 5 is the physical figure and the scanning electron micrograph of the keratin/silk fibroin composite porous material prepared in embodiment 5;

Figure 6 is the impact of CTAB concentration on the porosity of keratin/silk fibroin composite porous material and the removal rate of methylene blue dye;

Fig. 7 is the physical picture of the keratin/silk fibroin composite porous material that does not add CTAB prepared by comparative example 1;

Fig. 8 is a scanning electron micrograph of a porous material obtained by adding CTAB prepared in Comparative Example 2 to pure silk fibroin.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

Example 1

(1) Place 5 g of cleaned chicken feathers in 20 g of a deep eutectic solvent, add 7.5 g of water, vibrate and heat to dissolve the chicken feathers, filter, dialyze, and precipitate to obtain a keratin suspension. The deep eutectic solvent is composed of choline chloride and oxalic acid in a mass ratio of 1:2, the heating temperature is 80°C; the time is 6h, the shaking speed is 150rpm, and the molecular weight cut-off of the dialysis bag is 1kDa.

(2) Place 15 g of degummed silk in 100 g of LiBr solution, vibrate and heat to dissolve the silk, and obtain a silk fibroin solution after dialysis. The concentration of the LiBr solution was 9.5 mol/L, the heating temperature was 50° C., the time was 30 min, the shaking speed was 100 rpm, and the molecular weight cut-off of the dialysis bag was 3 kDa.

(3) Mix the keratin suspension in step (1) with the silk fibroin solution in step (2), and stir to prepare a keratin/silk fibroin mixed solution. The concentration of the keratin suspension is 2wt%, and the concentration of the silk fibroin solution is 5wt%. The stirring speed is 500 rpm; the stirring time is 10 minutes, and the mixing mass ratio of keratin suspension and silk fibroin solution is 3:2.

(4) Disperse CTAB in deionized water. The concentration of the CTAB solution was 2 wt%.

(5) Add the CTAB solution obtained in step (4) to the keratin/silk fibroin mixed solution obtained in step (3), stir evenly, pour it into a cell culture plate for shaping, and obtain a hydrogel after standing for a period of time . The mass ratio of the keratin/silk fibroin mixed solution in step (3) to the CTAB solution in step (4) is 10:1, and the standing time is 5min.

(6) Put the hydrogel obtained in step (5) into the freezer for quick freezing for 24 hours, and then freeze-dry to obtain a keratin/silk fibroin porous composite material with a large number of pores. The temperature for quick freezing is -40°C, and the time for freeze-drying is 48 hours.

Example 2

(1) With embodiment 1.

(2) With embodiment 1.

(3) The concentration of the keratin suspension is 2wt%; the concentration of the silk fibroin solution is 7wt%. All the other are with embodiment 1.

(4) Disperse CTAB in deionized water. The concentration of the CTAB solution was 4 wt%.

(5) with embodiment 1.

(6) With embodiment 1.

Example 3

(1) With embodiment 1.

(2) With embodiment 1.

(3) The concentration of the keratin suspension is 2.5wt%; the concentration of the silk fibroin solution is 7wt%. All the other are with embodiment 1.

(4) Disperse CTAB in deionized water. The concentration of CTAB was 6 wt%.

(5) with embodiment 1.

(6) The temperature for rapid freezing is -60°C. All the other are with embodiment 1.

Example 4

(1) With embodiment 1.

(2) With embodiment 1.

(3) The concentration of the keratin suspension is 2.5wt%; the concentration of the silk fibroin solution is 9wt%. All the other are with embodiment 1.

(4) Disperse CTAB in deionized water. The concentration of the CTAB solution was 6 wt%.

(5) with embodiment 1.

(6) The temperature for rapid freezing is -60°C. All the other are with embodiment 1.

Example 5

(1) With embodiment 1.

(2) With embodiment 1.

(3) The concentration of the keratin suspension is 3wt%; the concentration of the silk fibroin solution is 9wt%. All the other are with embodiment 1.

(4) Dispersing CTAB in deionized water, the concentration of CTAB solution is 8wt%.

(5) with embodiment 1.

(6) The temperature for rapid freezing is -80°C. All the other are with embodiment 1.

Comparative example 1

The keratin/silk fibroin composite porous material without adding CTAB, the preparation method is as follows:

(1) With embodiment 1.

(2) With embodiment 1.

(3) The concentration of the keratin suspension is 2.5wt%; the concentration of the silk fibroin solution is 7wt%. All the other are with embodiment 1.

(4) Pour the keratin/silk fibroin mixed solution obtained in step (3) into a cell culture plate for shaping, put it into a freezer for quick freezing for 24 hours after standing for 5 minutes, and then freeze-dry to obtain water-insoluble keratin Protein/Silk Fibroin Porous Composite. The temperature for quick freezing is -80°C, and the time for freeze-drying is 48 hours.

Comparative example 2

Add the porous material that CTAB obtains in the pure silk fibroin, the preparation method is as follows:

(1) Place 20 g of degummed silk in 100 g of LiBr solution, vibrate and heat to dissolve the silk, and obtain a silk fibroin solution after dialysis. The concentration of the LiBr solution was 9.5mol/L, the heating temperature was 60°C, the time was 30min, the shaking speed was 100rpm, and the molecular weight cut-off of the dialysis bag was 8kDa. The concentration of silk fibroin solution is 7.5wt%.

(2) Disperse CTAB in deionized water to obtain a CTAB solution with a concentration of 24 wt%.

(3) Add the CTAB solution obtained in step (2) to the silk fibroin solution obtained in step (1), stir evenly, pour it into a cell culture plate to shape it, and let it stand for 1 hour to obtain a hydrogel. The volume ratio of the silk fibroin solution in the step (1) to the CTAB solution in the step (2) is 2:1.

(4) Put the hydrogel obtained in step (3) into a freezer for quick freezing for 24 hours, and then freeze-dry to obtain a silk fibroin porous composite material. The temperature for quick freezing is -80°C, and the time for freeze-drying is 48 hours.

Comparative example 3

The concentration of CTAB solution is 16wt%, and the rest is the same as Comparative Example 2.

Comparative example 4

The concentration of CTAB solution is 8wt%, and the rest is the same as Comparative Example 2.

Comparative example 5

The concentration of CTAB solution is 4wt%, the rest is the same as Comparative Example 2.

Comparative example 6

The concentration of CTAB solution is 2wt%, and the rest is the same as Comparative Example 2.

The gel time required for the porous composite materials prepared in Examples 1, 2, 3 and 5 of the present invention and the porous material prepared in Comparative Example 2 is shown in the table below.

The time required for gelation under different surfactant concentrations in table 1

The higher the surfactant concentration, the faster the gelation speed, but the higher the concentration, the lower the porosity and adsorption performance of the porous material. The low surfactant concentration and fast gelation speed are favorable for the formation of porous materials with both uniform structure and high porosity. As can be seen from Table 1, when CTAB acts on pure silk fibroin, the surfactant concentration used is relatively high and the gelation speed is still slow. When the CTAB concentration is 8wt%, the gelation time needs 1h, and the present invention only needs 10min. In comparative example 2, even according to the maximum concentration of 24wt%, the minimum gel time still needs 30min. It can be seen that the gel speed in the present invention is more advantageous.

It can be seen from Figures 1-5 that the keratin/silk fibroin composite porous material prepared by the present invention can obtain composite porous materials with different distribution states of keratin and silk fibroin by adjusting the concentration of CTAB. It can be seen from Figure 6 that both the porosity of the keratin/silk fibroin composite porous material and the removal rate of methylene dyes gradually decreased with the increase of CTAB concentration. It can be seen from Figure 7 that without adding CTAB, the composite material is clearly layered, the upper layer is white silk fibroin, and the lower layer is black keratin with pigment. It can be seen from Figure 8 that the porous material obtained by adding CTAB to pure silk fibroin has a small porosity, and compared with the keratin/silk fibroin porous composite material prepared by the present invention, there is no abundant lobular and high specific surface area pore structure.

Apparently, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation. For those of ordinary skill in the art, on the basis of the above description, other changes or changes in various forms can also be made. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (9)

1. A porous composite characterized by: the porous composite material contains keratin, silk fibroin and a bromine-type quaternary ammonium salt cationic surfactant, and is obtained by adding keratin into a silk fibroin solution, adding the bromine-type quaternary ammonium salt cationic surfactant, and then performing injection molding and freeze drying; the keratin is water-insoluble keratin.

2. The porous composite material according to claim 1, characterized in that: the mass ratio of keratin, silk fibroin and bromine type quaternary ammonium salt cationic surfactant in the porous composite material is 8-12:6-22:1-5.

3. The porous composite material according to claim 1, characterized in that: the bromine quaternary ammonium salt cationic surfactant is one or more selected from cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide and octadecyl trimethyl ammonium bromide.

4. A method for preparing a porous composite material according to any one of claims 1 to 3, comprising the steps of:

(1) Placing animal hair in eutectic solvent, adding water, oscillating, heating, filtering, dialyzing to obtain mixed solution of water soluble keratin and non-water soluble keratin, precipitating, sucking supernatant, and taking lower layer keratin suspension with keratin suspension concentration of 2-3wt%;

dissolving degummed silk, oscillating, heating and dialyzing to obtain a silk fibroin solution, wherein the concentration of the silk fibroin solution is 5-9wt%;

(2) Mixing the keratin suspension and the silk fibroin solution obtained in the step (1) according to a mass ratio of 3:1-2 to obtain a keratin/silk fibroin mixed solution, adding a bromine-type quaternary ammonium salt cationic surfactant aqueous solution, performing injection molding, and standing to obtain a keratin/silk fibroin hydrogel, wherein the concentration of the bromine-type quaternary ammonium salt cationic surfactant aqueous solution is 2-8wt%, and the mass ratio of the bromine-type quaternary ammonium salt cationic surfactant aqueous solution to the keratin/silk fibroin mixed solution is 1:5-10;

(3) And (3) freeze-drying the keratin/fibroin hydrogel obtained in the step (2) to obtain the porous composite material.

5. The method of claim 4, wherein: in the step (1), the solution for dissolving silk is selected from one of lithium bromide, calcium chloride-ethanol-water ternary solvent and eutectic solvent.

6. The production method according to claim 5, characterized in that: the concentration of the lithium bromide is 9-10 mol/L.

7. The production method according to claim 4 or 5, characterized in that: the eutectic solvent is choline chloride and oxalic acid with the mass ratio of 1.

8. The method of claim 4, wherein: and (3) standing for 10-300min in the step (2).

9. Use of the porous composite material of any one of claims 1 to 3 in bioadsorption.

Images