WO2019128399A1

WO2019128399A1 - Biomass fluorescent carbon quantum dot and preparation method thereof

Info

Publication number: WO2019128399A1
Application number: PCT/CN2018/110827
Authority: WO
Inventors: 钟林新; 敬霜霜; 彭新文; 孙润仓
Original assignee: 华南理工大学
Priority date: 2017-12-29
Filing date: 2018-10-18
Publication date: 2019-07-04
Also published as: CN108059149A; CN108059149B

Abstract

A preparation method for a biomass fluorescent carbon quantum dot, comprising the following steps: (1) dispersing biomass hydrochar or low-temperature carbonized biomass in an alkaline solution at room temperature, followed by adding a hydrogen peroxide solution and stirring to obtain a transparent and clear carbon quantum dot solution; and (2) filtering the carbon quantum dot solution obtained in step (1), followed by dialysis to obtain a purified water-soluble carbon quantum dot.

Description

Biomass fluorescent carbon quantum dot and preparation method thereof

Technical field

The invention relates to the field of nano materials, in particular to a biomass fluorescent carbon quantum dot and a preparation method thereof.

Background technique

Quantum dots have superior optical and electrochemical properties. As quasi-zero-dimensional nanomaterials, they have quantum confinement effects, surface effects, size effects, etc. Therefore, quantum dots are used in optoelectronic devices, bioimaging, drug recognition, sensing, Good applications in the field of catalysis. However, the quantum dots of the system are mostly semiconductor quantum dots, and the heavy metal elements contained therein are biologically toxic, which limits its application. The development of low-toxic or non-toxic quantum dot materials to replace semiconductor quantum dots has received great attention and extensive research.

The carbon quantum dot is a carbon nanoparticle with a particle diameter of less than 10 nm. It is a basic structural unit of the future nanoelectronic device and a novel luminescent material, and has great potential application value in the field of biosensing and biomedicine. Compared with traditional quantum dots, carbon quantum dots not only have excellent optical and electrochemical properties, but also have low toxicity, chemical inertness, easy function, easy water solubility, good biocompatibility and high economic efficiency. It has shown attractive application prospects in biomedical fields such as photocatalysis, sensors, optoelectronic devices, and bioimaging and medical diagnostics.

There are two main methods for synthesizing carbon quantum dots, that is, the physical size or the chemical method is used to make the size of the bulk material small to the nano-scale bottom-up method, such as arc discharge method, laser ablation method, electrochemical method, etc. There is also a top-down method for preparing nanoscale carbon quantum dots by chemical synthesis from small to large carbon sources. The carbon source for preparing carbon quantum dots is developed from inorganic carbon materials such as carbon nanotubes, graphite, carbon black, candle ash, natural gas soot, activated carbon, charcoal ash, and carbon fiber to citric acid, sugar, starch, vitamins, Organic carbon-containing natural products such as peanut skin, watermelon rind and coffee grounds.

Currently, biomass carbon quantum dots are mainly prepared by hydrothermal reaction. The hydrothermal reaction of biomass is a chemical reaction in which a biomass is placed in a sealed pressure vessel and water is used as a solvent under certain conditions of temperature and pressure. After the hydrothermal reaction, the carbon quantum dots are suspended and dispersed in the solution, and the pure product can be further obtained by the steps of centrifugation, dialysis and purification. Due to the advantages of simple preparation of water and heat, green, and the controllable surface and size of the obtained quantum dots, it has been widely used in the preparation of fluorescent carbon quantum dots by biomass. The invention patent (201610054674.9, a N, P, S co-doped fluorescent carbon quantum dot, and a preparation method and application thereof) use a biomass fungus as a carbon source, and after removing a precipitated impurity by hydrothermal reaction, the obtained supernatant is It is an aqueous solution of carbon quantum dots. The invention patent (201410222883.0, a fluorescent amino carbon quantum dot, a preparation method thereof and application thereof) uses xylan as a carbon source, and after removing a hydrothermal reaction in an aqueous ammonia solution, the supernatant obtained by the precipitation is removed as a fluorescent amino carbon quantum aqueous solution. Invention patent (201410554087.7 a macro method for preparing fluorescent carbon quantum dots) The bee pollen is added to ultrapure water, ultrasonically treated, and then placed in a reaction vessel for hydrothermal reaction, followed by removal of the precipitate to obtain a fluorescent carbon quantum solution. Invention patent (201410753601.X method for preparing nitrogen-doped carbon quantum dots based on shrimp waste) hydrothermal reaction of shrimp waste and ultrapure water into a hydrothermal reaction kettle of tetrafluoroethylene, followed by suction filtration The filtrate was collected and purified by concentration and dried to obtain nitrogen-doped carbon quantum dots. However, in the process of hydrothermal preparation of biomass carbon quantum dots, a large amount of hydrothermal coke which is insoluble in solution is generated, and the amount of carbon quantum dots generated by hydrothermal suspension suspended in the reaction solution is small, and thus hydrothermal method The yield of carbon quantum is very low.

In the invention of biomass preparation of carbon quantum dots, there is also a partial bottom-up method in which the biomass material is first carbonized to obtain a carbon material, and then the carbon material is treated by other methods to make the size smaller to the nanometer level. Invention patent (201510439569.2 a soybean-based carbon quantum dot and porous carbon material and preparation thereof), the pulverized soybean is subjected to low-temperature carbonization treatment in an inert gas, the carbonized product is immersed in water, and then the supernatant is separated and purified to obtain a soybean-based carbon quantum dot. . The invention patent (201510096178.5 a preparation method of biomass-based carbon quantum dots) obtains a carbonization product by carbonizing or activating the biomass material, and nanometer-quantizing the carbonized product by using a concentrated acid mixture solution to obtain a water-soluble fluorescent carbon quantum dot. . In the process of processing carbon materials, such methods have the disadvantages of complicated process, high energy consumption, large environmental pollution, strong equipment corrosion, etc., and there are also insufficient carbon material decomposition, resulting in low yield of carbon quantum dots.

At present, the preparation process of biomass carbon quantum is complicated, consumes high energy, has large environmental pollution, and has low yield, which limits the large-scale production and application of carbon quantum dots. Therefore, it is of great significance and value to develop a simple, efficient and high yield biomass carbon quantum dot preparation method.

Summary of the invention

In order to overcome the above disadvantages and disadvantages of the prior art, an object of the present invention is to provide a method for preparing biomass fluorescent carbon quantum dots, which has the advantages of low energy consumption, high yield, environmental protection, simple operation, and low equipment cost.

Another object of the present invention is to provide a fluorescent carbon quantum dot of a substance obtained by the above production method.

The object of the invention is achieved by the following technical solutions:

A method for preparing biomass fluorescent carbon quantum dots, comprising the steps of:

(1) mixing the biomass, the basic substance, and the hydrogen peroxide with water at room temperature to obtain a mixed liquid, and stirring to obtain a transparent and clear carbon quantum dot solution;

The biomass is biomass hydrothermal coke or low temperature carbonized biomass;

(2) The carbon quantum dot solution obtained in the step (1) is filtered and dialyzed to obtain a purified water-soluble carbon quantum dot.

Preferably, the concentration of the hydrogen peroxide in the step (1) in the mixed solution is 0.001 to 1 g/mL.

Further preferably, the concentration of the hydrogen peroxide in the mixture in the step (1) is from 0.006 to 0.024 g/mL.

Preferably the mixture of step (1) in the OH ^- concentration of 0.0001 ~ 5mol / L.

Further preferably, the concentration of OH ^- in the mixed solution of the step (1) is from 0.01 to 0.5 mol/L.

Preferably, the mass of the biomass hydrothermal coke or the low temperature carbonized biomass in the step (1) is from 0.1% to 10% by mass of the mixed solution.

The preparation method of the biomass fluorescent carbon quantum dot, the preparation method of the biomass water thermal coke in the step (1) is as follows:

The biomass is used as a raw material, and water is used as a solvent to carry out a chemical reaction in a sealed pressure vessel to obtain a black solid product which is insoluble or not dispersed in the solution.

Preferably, the preparation method of the low-temperature carbonized biomass in the step (1) is as follows:

Using biomass as a raw material, carbonization at 150-350 ° C in an inert gas gives low temperature biomass carbon.

The biomass is at least one of glucose, fructose, xylose, glucosamine, citric acid, chitosan, chitin, hemicellulose, and cellulose.

A biomass fluorescent carbon quantum dot prepared by the method for preparing the biomass fluorescent carbon quantum dot.

Compared with the prior art, the present invention has the following advantages and benefits:

(1) Compared with the current method for obtaining carbon quantum dots by separating the night, the present invention has a high yield and can meet the requirements for mass production.

(2) The fluorescent carbon quantum dots prepared by the present invention are capable of emitting blue visible light under ultraviolet light excitation and have good light resistance.

(3) The raw materials used in the preparation process of the present invention are widely available, and are inexpensive and readily available.

(4) The preparation method of the present invention makes full use of the originally discarded, low-cost biomass water hot coke and low-temperature carbonized biomass carbon, and has the advantages of green environmental protection.

(5) The preparation method of the preparation method of the invention is cheap and easy to obtain, and the concentration of the medicine is low, the corrosion of the equipment is small, and the environmental pollution is small.

(6) The preparation process of the invention is simple, the equipment required is simple, and the cost is extremely low.

DRAWINGS

1 is a projection electron micrograph of a carbon quantum dot prepared in Example 1;

2 is a particle size distribution diagram of carbon quantum prepared in Example 1, which is obtained by 252 quantum dots in a statistical transmission electron microscope;

3 is a fluorescence spectrum of a quantum dot prepared in Example 1;

4 is a fluorescence spectrum of a quantum dot prepared in Example 2;

5 is a fluorescence spectrum of a quantum dot prepared in Example 3;

6 is a fluorescence spectrum of a quantum dot prepared in Example 4;

7 is a fluorescence spectrum of a quantum dot prepared in Example 6;

8 is a fluorescence spectrum of a quantum dot prepared in Example 7;

9 is a fluorescence spectrum of a quantum dot prepared in Example 8;

Figure 10 is a fluorescence spectrum of a quantum dot prepared in Example 9.

Detailed ways

The present invention will be further described in detail below with reference to the embodiments, but the embodiments of the present invention are not limited thereto.

Example 1

Weigh 0.1 g of glucose water hot coke in 50 mL of NaOH and H ₂ O ₂ mixed solution, wherein the NaOH concentration is 0.1 mol/L, the H ₂ O ₂ concentration is 0.01 g/mL, and the mixture is stirred thoroughly to obtain a brown clarified fluorescent carbon quantum. Point the solution. The carbon quantum dot solution is filtered and dialyzed to obtain a pure fluorescent carbon quantum dot. The fluorescence carbon quantum dot yield was 97.9%.

The fluorescent carbon quantum dots obtained in the present example were characterized by projection electron microscopy, particle size distribution, and fluorescence spectroscopy. The obtained carbon quantum dots were found to have good dispersibility in water, having a diameter of 1-4 nm and an average diameter of 2.42 nm (252 counts). The test results are shown in Figures 1, 2 and 3.

Example 2

Weigh 0.1 g of glucose water hot coke in 50 mL of NaOH and H ₂ O ₂ mixed solution, wherein the NaOH concentration is 0.1 mol/L, the H ₂ O ₂ concentration is 0.02 g/mL, and the mixture is stirred well to obtain a brown clarified fluorescent carbon quantum. Point the solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The fluorescent carbon quantum dot yield was 96.5%.

The fluorescent carbon quantum dots obtained in the present example were characterized by fluorescence spectroscopy, and the test results are shown in FIG.

Example 3

Weigh 0.1g of glucose water hot coke in 50mL NaOH and H ₂ O ₂ mixed solution, wherein the NaOH concentration is 0.05mol / L, the H ₂ O ₂ concentration is 0.02g / mL, and fully stirred to obtain a brown clarified fluorescent carbon quantum. Point the solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The yield of fluorescent carbon quantum dots was 43%.

Fluorescence spectroscopy of the fluorescent carbon quantum dots obtained in this example was carried out. The test results are shown in Fig. 5.

Example 4

Weigh 0.1g of glucosamine water hot coke in 50mL NaOH and H ₂ O ₂ mixed solution, wherein the NaOH concentration is 0.02mol / L, H ₂ O ₂ concentration is 0.01g / mL, and fully stirred to obtain brown clarified fluorescent carbon Quantum dot solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The yield of fluorescent carbon quantum dots was 96.3%.

The fluorescent carbon quantum dots obtained in the present example were characterized by fluorescence spectroscopy. The test results are shown in Fig. 6.

Example 5

Weigh 0.1g of glucosamine hydrothermal coke in 50mL NaOH and H ₂ O ₂ mixed solution, wherein the NaOH concentration is 0.02mol / L, H ₂ O ₂ concentration is 0.02g / mL, and fully stirred to obtain brown clarified fluorescent carbon Quantum dot solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The fluorescence carbon quantum dot yield was 44.5%.

Example 6

Weigh 0.1 g of industrial hemicellulose hydrothermal coke in 50 mL of NaOH and H ₂ O ₂ mixed solution, wherein the NaOH concentration is 0.05 mol/L, the H ₂ O ₂ concentration is 0.01 g/mL, and the mixture is stirred thoroughly to obtain brown clarified. Fluorescent carbon quantum dot solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The fluorescent carbon quantum dot yield was 96.5%.

The fluorescent carbon quantum dots obtained in this example were characterized by fluorescence spectroscopy. The test results are shown in FIG.

Example 7

Weigh 0.1g of chitosan hydrothermal coke in 50mL NaOH and H ₂ O ₂ mixed solution, wherein the concentration of NaOH is 0.05mol / L, the concentration of H ₂ O ₂ is 0.01g / mL, and fully stirred to obtain brown clarified fluorescent carbon Quantum dot solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The fluorescence carbon quantum dot yield was 97.3%.

Fluorescence spectroscopy of the fluorescent carbon quantum dots obtained in this example was carried out. The test results are shown in Fig. 8.

Example 8

Weigh 0.1g of cellulose hydrothermal coke in 50mL NaOH and H ₂ O ₂ mixed solution, wherein the NaOH concentration is 0.1mol / L, the H ₂ O ₂ concentration is 0.01g / mL, and fully stirred to obtain brown clarified fluorescent carbon Quantum dot solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The yield of fluorescent carbon quantum dots was 93.4%.

The fluorescent carbon quantum dots obtained in this example were characterized by fluorescence spectroscopy, and the test results are shown in FIG.

Example 9

0.1 g of biomass carbon obtained by low-temperature carbonization of glucose was dispersed in 50 mL of a mixed solution of NaOH and H ₂ O ₂ , wherein the concentration of NaOH was 0.1 mol/L, and the concentration of H ₂ O ₂ was 0.01 g/mL, and the mixture was thoroughly stirred to obtain brown clarified. Fluorescent carbon quantum dot solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The fluorescence carbon quantum dot yield was 76.9%.

The fluorescent carbon quantum dots obtained in the present example were characterized by fluorescence spectroscopy. The test results are shown in FIG.

Example 10

0.1 g of biomass carbon obtained by low-temperature carbonization of glucose was dispersed in 50 mL of a mixed solution of NaOH and H ₂ O ₂ , wherein the concentration of NaOH was 0.1 mol/L, and the concentration of H ₂ O ₂ was 0.02 g/mL, and the mixture was thoroughly stirred to obtain brown clarified. Fluorescent carbon quantum dot solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The yield of fluorescent carbon quantum dots was 65.06%.

Example 11

0.1 g of biomass carbon obtained by low-temperature carbonization of glucose was dispersed in 50 mL of a mixed solution of NaOH and H ₂ O ₂ , wherein the concentration of NaOH was 0.05 mol/L, and the concentration of H ₂ O ₂ was 0.02 g/mL, and the mixture was thoroughly stirred to obtain brown clarified. Fluorescent carbon quantum dot solution. The carbon quantum dot solution is filtered, dialyzed, and lyophilized to obtain a pure fluorescent carbon quantum dot. The yield of fluorescent carbon quantum dots was 56.1%.

Ink experiment

0.005 g of the fluorescent carbon quantum dots prepared in Example 1 was weighed and dissolved in water, and the sample was transferred to a 50 mL volumetric flask to obtain a fluorescent ink aqueous solution having a concentration of 0.1 mg/mL. Fluorescent ink is filtered and diluted with a microporous membrane, the ordinary brush is washed, the diluted fluorescent ink is washed off, and written on the filter paper. After the ink is naturally dried, it is irradiated with an ultraviolet lamp, and the filter paper is lightly printed at the writing position. Green pattern. The fluorescent ink is further prepared by the fluorescent carbon quantum dots prepared by the invention, and the fluorescence has no obvious change under the long-term ultraviolet light irradiation, and no photobleaching property is obtained.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments, and any other changes, modifications, substitutions, and combinations may be made without departing from the spirit and scope of the present invention. And simplifications, all of which are equivalent replacement means, are included in the scope of protection of the present invention.

Claims

A method for preparing biomass fluorescent carbon quantum dots, comprising the steps of:

(1) mixing the biomass, the basic substance, and the hydrogen peroxide with water at room temperature to obtain a mixed liquid, and stirring to obtain a transparent and clear carbon quantum dot solution;

The biomass is biomass hydrothermal coke or low temperature carbonized biomass;

(2) The carbon quantum dot solution obtained in the step (1) is filtered and dialyzed to obtain a purified water-soluble carbon quantum dot.
The method for producing a biomass fluorescent carbon quantum dot according to claim 1, wherein the concentration of the hydrogen peroxide in the mixed solution in the step (1) is 0.001 to 1 g/mL.
The method for preparing a biomass fluorescent carbon quantum dot according to claim 2, wherein the concentration of the hydrogen peroxide in the mixed solution in the step (1) is 0.006 to 0.024 g/mL.
The method for preparing a biomass carbon fluorescence quantum dot of claim 1 or claim 2, wherein the mixture of step (1) in the OH - concentration of 0.0001 ~ 5mol / L.
The method for preparing a biomass carbon fluorescent quantum dots as claimed in claim 4, wherein the step (1) a mixture of OH - concentration of 0.01 ~ 0.5mol / L.
The method for preparing biomass fluorescent carbon quantum dots according to claim 2 or 3, wherein the mass of the biomass hydrothermal coke or the low-temperature carbonized biomass in the step (1) is 0.1%-10% of the mass of the mixed solution. .
The method for preparing a biomass fluorescent carbon quantum dot according to claim 1, wherein the preparation method of the biomass water thermal coke in the step (1) is as follows:

The biomass is used as a raw material, and water is used as a solvent to carry out a chemical reaction in a sealed pressure vessel to obtain a black solid product which is insoluble or not dispersed in the solution.
The method for preparing a biomass fluorescent carbon quantum dot according to claim 1, wherein the method for preparing the low temperature carbonized biomass in the step (1) is as follows:

Using biomass as a raw material, carbonization at 150-350 ° C in an inert gas gives low temperature biomass carbon.
The method for preparing biomass fluorescent carbon quantum dots according to claim 1, wherein the biomass is glucose, fructose, xylose, glucosamine, citric acid, chitosan, chitin, hemicellulose, At least one of cellulose.
A biomass fluorescent carbon quantum dot obtained by the method for producing a biomass fluorescent carbon quantum dot according to any one of claims 1 to 8.