CN112301464B - A kind of gelatin-based carbon nanofiber and preparation method thereof - Google Patents

Abstract

The invention relates to a gelatin-based carbon nanofiber and a preparation method thereof, and the preparation method comprises the following steps: adding gelatin solid particles into deionized water, heating and stirring, adding an iron (III) complex which is soluble in water and has a high stability constant into a gelatin water solution to prepare a mixed spinning solution, and performing electrostatic spinning to prepare gelatin-based fibers; and pre-oxidizing and carbonizing the spun gelatin-based fibers to obtain the gelatin-based carbon nanofibers. The invention has the advantages that the carbon nanofiber is prepared by adopting the gelatin as the precursor, so that the high-efficiency utilization of resources is realized; the iron (III) complex with high stability constant is used as an auxiliary agent, so that the ferric ions and gelatin molecules are prevented from crosslinking and coagulating, and the defect that the gelatin fiber is melted into blocks at high temperature due to low glass transition temperature and the shape of the fiber is difficult to maintain is overcome. The preparation method is simple and environment-friendly, and the obtained gelatin-based carbon nanofiber has smooth surface, uniform thickness and high porosity and has certain application prospect in the fields of catalysis, adsorption and the like.

Description

A kind of gelatin-based carbon nanofiber and preparation method thereof

technical field

The invention relates to the technical field of nanomaterials, in particular to a gelatin-based carbon nanofiber and a preparation method thereof.

Background technique

As one-dimensional nanomaterials, carbon nanofibers have broad application prospects in the fields of catalysis and adsorption due to their excellent physical and chemical properties, good electrical conductivity and large specific surface area. Among many preparation methods, electrospinning is one of the most convenient methods for preparing carbon nanofibers. By changing the composition of the spinning solution and spinning parameters, the morphology, surface defects and heteroatoms of carbon nanofibers can be regulated. content. At present, there are many reports on the preparation of carbon nanofibers by electrospinning technology. Usually, high polymers such as polyacrylonitrile, pitch, and polyurethane are used as precursor spinning solutions. However, most of these high polymers belong to chemical products. Relying on fossil fuels, it is a non-renewable resource, and the preparation is complicated and expensive. At the same time, organic solvents such as N,N-dimethylformamide or tetrahydrofuran are used in the preparation of the spinning solution. These organic solvents are highly toxic and cannot be used in spinning The silk will volatilize into the surrounding environment, causing certain pollution. Therefore, the preparation of carbon nanofibers using a natural, renewable and environmentally friendly precursor spinning solution is one of the urgent problems to be solved.

As a naturally derived biomass material, gelatin is hydrolyzed from collagen and widely exists in mammalian skin and bones. The prepared gelatin fibers have been widely used in food, biomedicine and other fields. However, as a thermoplastic material, gelatin has a low glass transition temperature, which makes gelatin fibers melt into blocks during the high-temperature pre-oxidation and carbonization process, and it is difficult to maintain their original fiber morphology. Due to the difficulties caused by the characteristics, the research on the preparation of gelatin-based carbon nanofibers using gelatin as the precursor spinning solution has not been reported so far.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems existing in the prior art, and overcome the shortcomings of low glass transition temperature of gelatin fibers, easy melting at high temperature, and difficulty in maintaining fiber morphology, the present invention provides a gelatin-based carbon nanofiber and a preparation method thereof, wherein gelatin is used as the The carbon nanofibers are prepared from the precursors, which realizes the efficient utilization of resources; the use of iron (III) complexes with high stability constants as auxiliary agents not only prevents the cross-linking and aggregation of ferric ions and gelatin molecules, but also overcomes the problems of gelatin fibers. Due to the low glass transition temperature, it is difficult to maintain the fiber morphology when it is melted into a block at high temperature. Using specific electrospinning, pre-oxidation and carbonization treatment processes, gelatin-based carbon nanofiber materials were successfully prepared.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical scheme:

A preparation method of gelatin-based carbon nanofibers, comprising the following steps:

S1, adding gelatin solid particles into deionized water, heating and stirring to make it evenly mixed to obtain an aqueous gelatin solution;

S2, adding iron (III) complex that is soluble in water and has a high stability constant into the gelatin aqueous solution, and continues to heat and stir to mix it evenly;

S3, electrospinning the gelatin/iron (III) complex mixed spinning solution obtained above to obtain gelatin-based fibers;

S4, pre-oxidizing the spun gelatin-based fibers;

S5, carbonizing the pre-oxidized gelatin-based fibers to obtain gelatin-based carbon nanofibers.

In a preferred embodiment of the present invention, in step S1, the mass fraction of the gelatin aqueous solution is 10%-20%.

In a preferred embodiment of the present invention, in step S2, the iron (III) complex that is soluble in water and has a high stability constant includes sodium ferric EDTA and potassium ferricyanide.

In a preferred embodiment of the present invention, in step S2, the mass ratio of the gelatin to the iron (III) complex is 2-25.

In a preferred embodiment of the present invention, in steps S1 and S2, the heating and stirring are heating and stirring at 70-90° C. for 2-4 h.

In a preferred embodiment of the present invention, in step S3, the parameters of the electrospinning are: the spinning temperature is 55-80° C., the advancing speed of the syringe is 0.3-1.3 mL h ^-1 , and the spinning voltage is controlled as 10-20kV.

In a preferred embodiment of the present invention, in step S4, the pre-oxidation conditions are: in an air atmosphere, the temperature is raised from room temperature to 100-150 ℃ at a heating rate of 1-5 ℃ min ^-1 , and the temperature is kept for 1- After 2 h, the temperature was raised to 250-310 °C at a heating rate of 1-2 °C min ^-1 , and the holding time was 0.5-2 h.

In a preferred embodiment of the present invention, in step S5, the carbonization treatment conditions are as follows: in an inert gas atmosphere, the temperature is raised from room temperature to 500-1000 °C at a heating rate of 2-5 °C min ^-1 , and the temperature is kept for a long time. for 1-3 h, and then naturally cooled to room temperature.

In a preferred embodiment of the present invention, the inert gas atmosphere is one or both of nitrogen and argon.

The present invention also protects the gelatin-based carbon nanofibers prepared by the above-mentioned preparation method.

Compared with the prior art, the beneficial technical effects of the present invention are:

1. The present invention uses iron (III) complexes with high stability constants as auxiliary agents, in which Fe ³⁺ can catalyze the cyclization and dehydrogenation processes of gelatin molecules during the pre-oxidation process of gelatin fibers. At the same pre-oxidation temperature, compared with the gelatin fibers without iron(III) complexes, the gelatin fibers with iron(III) complexes can form more heat-resistant conjugated ladder structures faster, thereby improving the The thermal stability of gelatin has been solved, and the problem that gelatin fibers cannot be maintained in a lump when melted at high temperature is solved. Combined with specific electrospinning, pre-oxidation and carbonization treatment processes, gelatin-based carbon nanofibers have been successfully realized. preparation.

2. Using the strong coordination effect of Fe ³⁺ and ligands in the iron (III) complex with high stability constant, it can effectively avoid the coagulation and sedimentation of Fe ³⁺ and gelatin molecules when preparing the spinning solution, thereby ensuring the spinning stability. went well.

3. Using gelatin as carbon nanofiber precursor and gelatin as biomass material can realize efficient utilization of resources.

4. The use of water as the solvent avoids the use of organic solvents and is more environmentally friendly.

5. The preparation method of the present invention is simple and environmentally friendly, and the obtained gelatin-based carbon nanofibers have smooth surface, uniform thickness and high porosity, and have certain application prospects in the fields of catalysis and adsorption.

Description of drawings

Further description is given below in conjunction with the accompanying drawings.

Fig. 1 is the scanning electron microscope photo of gelatin-based carbon nanofibers prepared in Example 1;

Fig. 2 is the SEM photo of gelatin-based carbon nanofibers prepared in Example 2;

Fig. 3 is the SEM photo of gelatin-based carbon nanofibers prepared in Example 3;

FIG. 4 is a scanning electron microscope photograph of the samples prepared in the comparative example.

Detailed ways

The specific embodiments of the present invention will be described below with reference to the accompanying drawings and examples, but the following examples are only used to describe the present invention in detail, and do not limit the scope of the present invention in any way.

Example 1

1.25 g of gelatin solid particles were added to 7 g of deionized water, heated and stirred at 70 °C for 2 h to prepare an aqueous gelatin solution with a mass fraction of 15 %. 62.5 mg of sodium ferric EDTA was added to the aqueous gelatin solution, and the mass ratio of gelatin solids to sodium ferric EDTA was 20:1, and heating and stirring were continued for 2 h. The gelatin/sodium ferric ethylenediaminetetraacetate mixed spinning solution obtained above was sucked into the syringe, and then loaded into the electrospinning machine. 0.53 mL h ^-1 , and the spinning voltage was controlled to 15.0 kV) for electrospinning to obtain gelatin-based fibers. The spun gelatin-based fibers were placed in a muffle furnace, and under specific pre-oxidation conditions (under an air atmosphere, the temperature was increased from room temperature to 150 °C at a heating rate of 5 °C min ^-1 for 2 h, and then at 1 °C). The pre-oxidation operation was carried out at the heating rate of min ^-1 to 270 °C, and the holding time was 1 h). The pre-oxidized gelatin-based fibers were placed in a tube furnace and subjected to a certain program of carbonization treatment (under an argon atmosphere, the temperature was increased from room temperature to 700 °C at a heating rate of 5 °C min ^-1 , and the holding time was 1 h. , and then naturally cooled to room temperature) to obtain gelatin-based carbon nanofibers. The gelatin-based carbon nanofibers obtained in Example 1 are shown in FIG. 1 .

Example 2

Change the mass of sodium ferric EDTA powder to 125 mg, that is, the mass ratio of gelatin solids to sodium ferric EDTA powder is 10:1, and at the same time change the advancing rate of the syringe during spinning to 0.7 mL h ^-1 , the spinning voltage was controlled to 18.5 kV, and other experimental conditions and processes were the same as in Example 1. The gelatin-based carbon nanofibers obtained in Example 2 are shown in FIG. 2 .

Example 3

1.25 g of gelatin solid particles were added to 7 g of deionized water, heated and stirred at 70 °C for 2 h to prepare an aqueous gelatin solution with a mass fraction of 15 %. 110 mg of potassium ferricyanide was added to the aqueous gelatin solution, and the mass ratio of gelatin solids to potassium ferricyanide was 125:11, and heating and stirring were continued for 2 h. The pre-oxidation conditions were changed as follows: in an air atmosphere, the temperature was increased from room temperature to 150 °C at a heating rate of 5 °C min ^-1 , maintained for 2 h, and then heated to 310 °C at a heating rate of 1 °C min ^-1 , and the holding time was 1 h. Other experimental conditions and procedures are the same as in Example 1. The gelatin-based carbon nanofibers obtained in Example 3 are shown in FIG. 3 .

Comparative ratio

1.25 g of gelatin solid particles were added to 7 g of deionized water, heated and stirred at 70 °C for 4 h to prepare an aqueous gelatin solution with a mass fraction of 15 %. The gelatin spinning solution obtained above was sucked into a ^syringe , and then loaded into an electrospinning machine. Electrospinning was performed under the control of 18.5 kV) to obtain gelatin fibers. The spun gelatin fibers were placed in a muffle furnace, and under specific pre-oxidation conditions (under an air atmosphere, the temperature was increased from room temperature to 150 °C at a heating rate of 5 °C min ^-1 for 2 h, and then at 1 °C min -1 ) ^. The heating rate of ¹ was raised to 270 °C, and the holding time was 1 h) for pre-oxidation. The pre-oxidized gelatin fibers were placed in a tube furnace and subjected to a certain program of carbonization (under an argon atmosphere, the temperature was raised from room temperature to 700 °C at a heating rate of 5 °C min ^-1 , and the holding time was 1 h, Then naturally cooled to room temperature) to obtain the comparative sample, as shown in Figure 4, because the gelatin fibers melted at high temperature, the fiber morphology could not be maintained, and the prepared comparative sample was lumpy.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited to this, and any changes or substitutions that are not conceived of without creative work should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims (5)

1. a preparation method of gelatin-based carbon nanofibers, is characterized in that, comprises the following steps: S1, the gelatin solid particles are added to deionized water, heated and stirred to make it evenly mixed to obtain an aqueous gelatin solution; S2, adding iron (III) complex that is soluble in water and has a high stability constant into the gelatin aqueous solution, and continues to heat and stir to mix it evenly; S3, electrospinning the gelatin/iron (III) complex mixed spinning solution obtained above to obtain gelatin-based fibers; S4, pre-oxidizing the spun gelatin-based fibers; S5, carbonizing the pre-oxidized gelatin-based fibers to obtain gelatin-based carbon nanofibers; In step S2, the iron (III) complex that can be dissolved in water and has a high stability constant includes sodium ferric EDTA and potassium ferricyanide; In step S3, the parameters of the electrospinning are: the spinning temperature is 55-80 °C, the advancing speed of the syringe is 0.3-1.3 mL h ^-1 , and the spinning voltage is controlled to be 10-20 kV; In step S4, the pre-oxidation conditions are: in an air atmosphere, the temperature is raised from room temperature to 100-150 °C at a heating rate of 1-5 °C min ^-1 , maintained for 1-2 h, and then heated at a temperature of 1-2 °C min -1. The heating rate of ^-1 was heated to 250-310 °C, and the holding time was 0.5-2 h; In step S5, the carbonization treatment conditions are as follows: in a nitrogen or argon atmosphere, the temperature is raised from room temperature to 500-1000 °C at a heating rate of 2-5 °C min ^-1 , the holding time is 1-3 h, and then the temperature is naturally increased. Cool down to room temperature. 2. preparation method according to claim 1, is characterized in that, in step S1, the massfraction of described aqueous gelatin solution is 10%-20%. 3. The preparation method according to claim 1, wherein in step S2, the mass ratio of the gelatin to the iron (III) complex is 2-25. 4 . The preparation method according to claim 1 , wherein, in steps S1 and S2 , the heating and stirring are heating and stirring at 70-90° C. for 2-4 h. 5 . 5. The gelatin-based carbon nanofibers prepared by the preparation method according to any one of claims 1-4.

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