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Method for preparing carbon quantum dots from waste green tea residues and application of carbon quantum dots

A technology of carbon quantum dots and green tea, which is applied in the field of scavenging DPPH free radicals, can solve problems such as waste tea residue, achieve good dispersion, simple preparation steps, and good water solubility

Pending Publication Date: 2020-11-06
SHANXI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A large amount of waste tea residue is produced after tea soaking, which brings certain environmental problems

Method used

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  • Method for preparing carbon quantum dots from waste green tea residues and application of carbon quantum dots
  • Method for preparing carbon quantum dots from waste green tea residues and application of carbon quantum dots
  • Method for preparing carbon quantum dots from waste green tea residues and application of carbon quantum dots

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Experimental program
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Effect test

Embodiment 1

[0027] [Example 1] Preparation of carbon quantum dots by using waste green tea residue hydrothermal method

[0028] S1. Wash the waste green tea residue soaked with ultrapure water three times to remove impurities attached to the surface of the tea leaves;

[0029] S2. After cleaning, the waste green tea residue is dried in an oven at 60° C. and set aside;

[0030] S3. Get 6g of waste green tea residue soaked in 100mL ultrapure water, and transfer it to a 200mL polytetrafluoroethylene hydrothermal reactor;

[0031] S4. React in an oven at 180°C for 4 hours;

[0032] S5. After cooling the polytetrafluoroethylene hydrothermal reactor to room temperature, centrifuge the obtained solution at 5000rpm for 20min, dialyze through a 500-1000Da dialysis bag for 1 day, and change the water every 6h to obtain pure carbon quantum point water solution;

[0033] S6. Pre-freeze the above-mentioned carbon quantum dot aqueous solution in the freezer of the refrigerator for 30 hours to obtain...

Embodiment 2

[0036] [Example 2] Using waste green tea carbon quantum dots to scavenge DPPH free radicals

[0037] S1. Take 0.1g of carbon quantum dots in a beaker, dissolve them in deionized water, and set the volume in a 100mL volumetric flask, the concentration of which is 1.0mg / mL waste green tea carbon quantum dots solution.

[0038] S2. Take 0 μL, 5 μL, 10 μL, 15 μL, 20 μL, 25 μL, 30 μL, 35 μL, 40 μL, 45 μL, 50 μL of 1.0 mg / mL waste green tea carbon quantum dot solution respectively in 2 mL of 100 μmol / L DPPH ethanol solution, shake at room temperature Shake the reaction for 3 minutes, pour it into a cuvette, and use a UV-2450 ultraviolet-visible spectrophotometer to record the absorption value A at the maximum absorption wavelength of 520nm. 0 and A i , the results are shown in Table 1.

[0039] S3.DPPH free radical scavenging rate is carried out according to the following formula:

[0040]

[0041] In formula (1),

[0042] A 0 Indicates the absorbance value at 520nm when DPP...

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Abstract

The invention discloses a method for preparing carbon quantum dots from waste green tea residues, and belongs to the technical field of free radical scavenging. The method comprises the following steps of: carrying out hydrothermal reaction on dry waste green tea residues and pure water; carrying out dialysis treatment on an obtained product solution; and carrying out freeze drying to obtain the carbon quantum dots. The particle size of the obtained carbon quantum dots is about 3nm, and a transmission electron micrograph shows that the carbon quantum dots have good dispersity; infrared spectroscopy shows that hydrophilic groups such as hydroxyl, carbonyl and the like exist on the surfaces of the carbon quantum dots, and the water solubility of the carbon quantum dots is good. The waste green tea carbon quantum dots are used for scavenging free radicals DPPH. Preferably, the concentration of a waste green tea carbon quantum dot solution is 5-18.7 microgramme / mL, the scavenging rate canreach up to 94.2% and is equivalent to the scavenging rate of ascorbic acid on DPPH free radicals, and therefore, the waste green tea carbon quantum dots are expected to become an ideal substitute ofthe ascorbic acid.

Description

technical field [0001] The invention relates to the technical field of free radical scavenging, in particular to the application of carbon quantum dots prepared from waste green tea to the scavenging of DPPH free radicals. Background technique [0002] Free radicals, also known as "free radicals" in chemistry, refer to atoms or groups with unpaired electrons formed by homolytic covalent bonds of molecules of compounds under external conditions such as light and heat. Free radical atoms or molecules with unpaired electrons are usually produced by a series of enzymatic or non-enzymatic oxidation reactions in the human body. When the human body is under normal physiological conditions, a certain amount of free radicals plays an important role in maintaining normal physiological functions, such as signal transduction, resistance to external invasion by microorganisms, and gene expression. However, in some pathological conditions, the human body may produce a large number of fre...

Claims

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Application Information

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IPC IPC(8): C01B32/15C09K11/65C09K15/02B82Y20/00B82Y30/00
CPCC01B32/15C09K11/65C09K15/02B82Y20/00B82Y30/00C01P2004/04C01P2004/64
Inventor 张君秋张勇
Owner SHANXI UNIV