CN113304732B

CN113304732B - Porous composite material, preparation method and application thereof

Info

Publication number: CN113304732B
Application number: CN202110638726.8A
Authority: CN
Inventors: 冯勇; 杨旭红; 张旭
Original assignee: Suzhou University
Current assignee: Suzhou University
Priority date: 2021-06-08
Filing date: 2021-06-08
Publication date: 2023-02-10
Anticipated expiration: 2041-06-08
Also published as: CN113304732A

Abstract

The invention relates to a porous composite material, a preparation method and application thereof, wherein 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 carrying out injection molding and freeze drying. The porous composite material prepared by the rapid gelling technology and the freeze drying treatment has the advantages of high porosity, large specific surface area, excellent adsorption performance and the like.

Description

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 application thereof.

Background

With the development of socioeconomic and industrial processes, more and more industrial waste water is generated. Many industrial waste water contains dye or heavy metal ions which are not easy to degrade, especially the dye waste water has certain toxicity, mixed components and high organic pollutant content, and if the dye waste water is discharged into a water body and flows into an ecological system, the dye waste water can be gradually enriched by aquatic organisms, and finally the health of human beings is damaged.

Currently, adsorption methods are used in practice, either by electrostatic interaction (interaction between positively charged metal ions and negatively charged matrix) or by integration (formation of a coordinate covalent bond with metal ions by a lone pair of electrons provided by the matrix). The commonly used adsorbents comprise activated carbon, bentonite, zeolite and a biological adsorbent, wherein the biological adsorbent has the advantages of rich sources, various varieties, low cost, large adsorption capacity, high speed and the like, and can make up the defects of the traditional treatment method and is widely concerned.

CN106279749A discloses a preparation method of alginate and silk fibroin composite sponge, wherein a sodium alginate and silk fibroin mixed solution is mechanically stirred and then directly freeze-dried, so that the sodium alginate and the silk fibroin in the composite sponge are easily distributed unevenly; CN110669247A discloses a preparation method of attapulgite-based silk sodium alginate composite aerogel, but the gelling process is long, and the delamination of two materials in the composite is easy to cause.

The mixture of the keratin and the fibroin can fully utilize the good adsorption performance of the keratin and the good mechanical performance of the fibroin, so that the composite material has the possibility of being applied to actual production and life. However, the keratin and silk fibroin solution are easily layered after being mixed only by simple mechanical stirring action, which is not beneficial to the improvement of the mechanical property of the composite material. Therefore, there is still a need for an adsorbent material that is simple to produce, short in gelation time, and uniform in structure.

Disclosure of Invention

In order to solve the technical problems, the invention provides a porous composite material, which is prepared by extracting water-insoluble keratin and uniformly mixing the water-insoluble keratin with silk fibroin, adding a proper amount of bromine quaternary ammonium salt cationic surfactant into a mixed solution to realize rapid gelation, and fixing the keratin and the silk fibroin in the mixed solution to form the porous keratin/silk fibroin composite material.

The porous composite material contains keratin, silk fibroin and bromine quaternary ammonium salt cationic surfactant, and is obtained by adding the keratin into a silk fibroin solution, adding the bromine quaternary ammonium salt cationic surfactant, and then performing injection molding and freeze drying.

The invention adds keratin into the silk fibroin solution, and the interaction between the silk fibroin and the carboxyl and amide groups on the keratin molecules promotes the silk fibroin to be converted from an amorphous structure to a beta-folded structure to form a network structure formed by the mixed beta-folded crystals of the keratin and the silk fibroin, thereby being beneficial to the formation of gel and having uniform structure. Meanwhile, the silk fibroin beta-folding structure is increased, so that more hydrophobic chain segments are exposed from silk fibroin molecules, and the hydrophobic association between the hydrophobic chain segments of the bromine-type quaternary ammonium salt cationic surfactant and the silk fibroin molecule chains and between the silk fibroin molecule chains is enhanced, so that the gelling speed is greatly improved, and the effect of rapid gelling can be achieved under the condition of only adding a low-concentration surfactant.

Further, the keratin is a water-insoluble keratin. Aims to increase the water solubility resistance of the composite material, prevent the loss of keratin and improve the reutilization property of the composite material.

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

Further, the cationic surfactant of the bromine quaternary ammonium salt is one or more selected from Cetyl Trimethyl Ammonium Bromide (CTAB), decyl trimethyl ammonium bromide (DETAB), dodecyl Trimethyl Ammonium Bromide (DTAB), and octadecyl trimethyl ammonium bromide (STAB).

The invention also claims the application of the porous composite material in bioadsorption.

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

(1) Placing animal hair in eutectic solvent, adding water, oscillating, heating, filtering, dialyzing to obtain mixed solution of water soluble keratin and water insoluble keratin, precipitating, sucking supernatant, and collecting 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;

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

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

Further, in the step (1), the silk fibroin extraction solution is selected from one of lithium bromide, calcium chloride-ethanol-water ternary solvent and eutectic solvent. In a solvent, the combination of silk fibroin and water is gradually enhanced so as to be gradually expanded, then the silk fibroin is gradually broken into a sheet layer shape, the crystal structure is destroyed, the silk fibroin is changed from beta-folding to irregular curling, and the silk fibroin is dissolved.

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

Further, the eutectic solvent is choline chloride and oxalic acid with the mass ratio of 1. The different matching types of the hydrogen acceptor and the hydrogen donor of the eutectic solvent can cause great difference between the melting point and the dissolving capacity of the eutectic solvent, the keratin extraction temperature of 70-90 ℃ does not cause rapid reduction of the keratin molecular weight, and a large amount of energy consumption can be avoided.

Further, in the step (1), the keratin is extracted by shaking at 70-90 ℃ for 5-7h.

Further, in the step (1), the silk fibroin is oscillated for 0.5-1h at 40-60 ℃ during extraction.

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

Further, in the step (2), the gelation speed of the composite solution can be changed by adjusting the concentration of CTAB, and the higher the concentration is, the faster the gelation speed is, so as to obtain the composite porous material with different distribution states of keratin and silk fibroin, thereby controlling the pore structure of the porous material.

Further, in the step (2), standing for 10-300min.

Further, in the step (3), freeze-drying is performed at-40 to-80 ℃. The composite material containing a large number of pore structures is prepared by freeze drying, the specific surface area of the material is further increased, and adsorption sites in the keratin and the fibroin are fully exposed, so that the composite material has good adsorption capacity.

By means of the scheme, the invention at least has the following advantages:

(1) The porous composite material prepared by natural keratin and fibroin through rapid gel technology and freeze drying treatment has the characteristics of high porosity, large specific surface area, excellent adsorption performance, pure nature and no pollution. Keratin and fibroin, as protein polymers, are composed of a large number of various amino acids and contain abundant active groups such as amino groups, carboxyl groups, hydroxyl groups and the like. The active groups can provide enough adsorption sites for dye adsorption, the adsorption performance of the composite material is ensured, and the keratin after heavy metal ions are adsorbed can be desorbed under an acidic condition, so that the keratin is convenient to recycle, and has good application prospects in the fields of printing and dyeing wastewater treatment and the like.

(2) The invention can realize quick gelatinization, thereby quickly locking the keratin and the silk fibroin after mutually uniform dispersion and avoiding the layering phenomenon.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following description is made with reference to the preferred embodiments of the present invention and the accompanying detailed drawings.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference will now be made in detail to the present disclosure, examples of which are illustrated in the accompanying drawings.

Fig. 1 is a physical image and a scanning electron microscope image of the keratin/fibroin composite porous material prepared in example 1;

FIG. 2 is a physical image and a scanning electron microscope image of the keratin/fibroin composite porous material prepared in example 2;

FIG. 3 is a physical image and a scanning electron microscope image of the porous keratin/fibroin composite material prepared in example 3;

FIG. 4 is a physical image and a scanning electron microscope image of the porous keratin/fibroin composite material prepared in example 4;

fig. 5 is a physical image and a scanning electron microscope image of the keratin/fibroin composite porous material prepared in example 5;

FIG. 6 is a graph showing the effect of CTAB concentration on the porosity and methylene blue dye removal rate of a keratin/fibroin composite porous material;

FIG. 7 is a diagram showing a sample of the keratin/fibroin composite porous material prepared in comparative example 1 without CTAB;

FIG. 8 is a scanning electron microscope image of a porous material obtained by adding CTAB prepared in comparative example 2 to pure silk fibroin.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

Example 1

(1) Washing 5g of chicken feather, putting the chicken feather into 20g of eutectic solvent, adding 7.5g of water, shaking and heating to dissolve the chicken feather, and filtering, dialyzing and precipitating to obtain a keratin suspension. The eutectic solvent is prepared from choline chloride and oxalic acid in a mass ratio of 1:2, the heating temperature is 80 ℃; the time was 6h, the shaking speed was 150rpm and the dialysis bag had a molecular weight cut-off of 1kDa.

(2) And (3) placing 15g of degummed silk into 100g of LiBr solution, oscillating and heating to dissolve the silk, and dialyzing to obtain the silk fibroin solution. The concentration of the LiBr solution is 9.5mol/L, and the heating temperature is 50 ℃; the time is 30min, the shaking speed is 100rpm, and the molecular weight cut-off of the dialysis bag is 3kDa.

(3) And (3) mixing the keratin suspension in the step (1) with the silk fibroin solution in the step (2), and stirring 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 500rpm; the stirring time is 10 minutes, and the mass ratio of the mixture of the keratin suspension and the silk fibroin solution is 3.

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

(5) And (5) adding the CTAB solution obtained in the step (4) into the keratin/fibroin mixed solution obtained in the step (3), uniformly stirring, pouring into a cell culture plate for shaping, and standing for a period of time to obtain the hydrogel. And (3) the mass ratio of the keratin/fibroin mixed solution in the step (3) to the CTAB solution in the step (4) is 10, and the standing time is 5min.

(6) And (4) putting the hydrogel obtained in the step (5) into a freezing chamber, quickly freezing for 24 hours, and then carrying out freeze drying to obtain the keratin/silk fibroin porous composite material with a large number of pores. The temperature for quick freezing is-40 deg.C, and the time for freeze drying is 48h.

Example 2

(1) The same as in example 1.

(2) The same as in example 1.

(3) The concentration of the keratin suspension is 2wt%; the concentration of the silk fibroin solution was 7wt%. The rest is the same as example 1.

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

(5) The same as in example 1.

(6) The same as in example 1.

Example 3

(1) The same as in example 1.

(2) The same as in example 1.

(3) The concentration of the keratin suspension was 2.5wt%; the concentration of the silk fibroin solution was 7wt%. The rest is the same as example 1.

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

(5) The same as in example 1.

(6) The temperature for flash freezing was-60 ℃. The rest is the same as example 1.

Example 4

(1) The same as in example 1.

(2) The same as in example 1.

(3) The concentration of the keratin suspension was 2.5wt%; the concentration of the silk fibroin solution was 9wt%. The rest is the same as example 1.

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

(5) The same as in example 1.

Example 5

(1) The same as in example 1.

(2) The same as in example 1.

(3) The concentration of the keratin suspension is 3wt%; the concentration of the silk fibroin solution was 9wt%. The rest is the same as example 1.

(4) CTAB was dispersed in deionized water at a concentration of 8wt%.

(5) The same as in example 1.

(6) The temperature for flash freezing was-80 ℃. The rest is the same as example 1.

Comparative example 1

The preparation method of the keratin/fibroin composite porous material without CTAB comprises the following steps:

(1) The same as in example 1.

(2) The same as in example 1.

(4) Pouring the keratin/fibroin mixed solution obtained in the step (3) into a cell culture plate for shaping, standing for 5min, then placing into a freezing chamber for quick freezing for 24h, and then carrying out freeze drying to obtain the water-insoluble keratin/fibroin porous composite material. The temperature for quick freezing is-80 deg.C, and the time for freeze drying is 48h.

Comparative example 2

The preparation method of the porous material obtained by adding CTAB into pure silk fibroin is as follows:

(1) And (3) placing 20g of degummed silk into 100g of LiBr solution, oscillating and heating to dissolve the silk, and dialyzing to obtain the silk fibroin solution. The concentration of the LiBr solution is 9.5mol/L, and the heating temperature is 60 ℃; the time is 30min, the shaking speed is 100rpm, and the cut-off molecular weight of the dialysis bag is 8kDa. The concentration of the silk fibroin solution was 7.5wt%.

(2) CTAB was dispersed in deionized water to give a CTAB solution with a concentration of 24 wt%.

(3) And (3) adding the CTAB solution obtained in the step (2) into the silk fibroin solution obtained in the step (1), uniformly stirring, pouring into a cell culture plate for shaping, and standing for 1h to obtain the hydrogel. The volume ratio of the silk fibroin solution in the step (1) to the CTAB solution in the step (2) is 2.

(4) And (4) putting the hydrogel obtained in the step (3) into a freezing chamber, quickly freezing for 24h, and then freeze-drying to obtain the fibroin porous composite material. The temperature for quick freezing is-80 deg.C, and the time for freeze drying is 48h.

Comparative example 3

The concentration of CTAB solution was 16wt%, as in comparative example 2.

Comparative example 4

The concentration of CTAB solution was 8wt%, as in comparative example 2.

Comparative example 5

The concentration of CTAB solution was 4wt%, as in comparative example 2.

Comparative example 6

The concentration of CTAB solution was 2wt%, the rest being the same as in comparative example 2.

The time required for the gels of the porous composite materials prepared in examples 1, 2, 3 and 5 according to the present invention and the porous material prepared in comparative example 2 is shown in the following table.

TABLE 1 time required for gelation at different surfactant concentrations

The higher the concentration of the surfactant, the faster the gelling speed, but too high a concentration leads to a decrease in the porosity and adsorption properties of the porous material. The surfactant concentration is low, the gelling speed is high, and the porous material with a uniform structure and high porosity is formed. As can be seen from Table 1, CTAB acts on pure silk fibroin with a relatively high concentration of surfactant and a slow gelling rate, and at a CTAB concentration of 8wt%, the gelling time required was 1h, the invention required only 10min, whereas in comparative example 2, the gelling time required was 30min even at a maximum concentration of 24 wt%. The gel speed in the present invention is seen to be more advantageous.

As can be seen from FIGS. 1 to 5, the composite porous material of keratin and silk fibroin with different distribution states can be obtained by adjusting the concentration of CTAB in the prepared keratin/silk fibroin composite porous material. As can be seen from fig. 6, the porosity and the removal rate of the methylene dye of the keratin/silk fibroin composite porous material both gradually decreased with the increase of the CTAB concentration. As can be seen from fig. 7, in the case where CTAB is not added, the composite material is clearly layered, the upper layer is white silk fibroin, and the lower layer is black keratin with pigment. As can be seen from FIG. 8, the porosity of the porous material obtained by adding CTAB into pure silk fibroin is small, and compared with the keratin/silk fibroin porous composite material prepared by the invention, the porous material has no abundant splinter and pore structure with high specific surface area.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Various other modifications and alterations will occur to those skilled in the art upon reading the foregoing description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.

Claims

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%;

(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;

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.