Lignin carbon quantum dot fluorescent bamboo fiber, preparation method and application

Abstract

The application discloses lignin carbon quantum dot fluorescent bamboo fiber, a preparation method and application thereof, and relates to the technical field of bamboo fiber, in particular to a lignin carbon quantum dot fluorescent bamboo fiber, a preparation method and application thereof. The preparation method of the lignin carbon quantum dot fluorescent bamboo fiber comprises the following steps: selecting a rough planed bamboo strip sample, drying the bamboo strip sample at 80-90 DEG C until the moisture content is less than 30%, and sequentially cleaning the surface of the bamboo strip sample by using anhydrous ethanol and acetone, and then preparing the bamboo strip sample; mixing choline chloride, oxalic acid and deionized water and stirring uniformly to prepare a delignification aqueous solution; and the like. The lignin carbon quantum dot fluorescent bamboo fiber, the preparation method and the application thereof separate and treat bamboo cells, obtain bamboo fibers with high strength, use alkali lignin as a carbon source, hydrogen peroxide as an oxidant, and a small amount of p-phenylenediamine as a nucleating agent, successfully prepare lignin carbon quantum dots with yellow-green fluorescent emission by using a hydrothermal method, and combine the lignin carbon quantum dots with the bamboo fibers to prepare carbon quantum dot fluorescent bamboo fibers with fluorescent properties, and the carbon quantum dot fluorescent bamboo fibers have certain application prospects in the fields of anti-fake marks and intelligent textiles.

Description

Technical Field

[0001] This invention relates to the field of bamboo technology development and modification technology, specifically to a lignin carbon quantum dot fluorescent bamboo fiber, its preparation method, and its application. Background Technology

[0002] Bamboo resources are a renewable energy source, and bamboo, as a widely available, fast-growing natural material, is widely used in various fields. Unlike other biomass materials, bamboo has advantages such as rapid growth, high fiber strength, and high flexibility. Furthermore, the microscopic cellular structure of bamboo is relatively simple, with thick cell walls and thin cell lumens, making it easy to separate. Researchers hope to leverage this unique structure to broaden the functions and applications of bamboo fiber by directionally isolating and utilizing bamboo fiber cells.

[0003] Carbon quantum dots (CQDs) have attracted considerable attention as a novel luminescent material due to their simple preparation strategy, excellent fluorescence properties, and non-toxicity. Current research has shown that CQDs are being used in various fields, including bioimaging, biosensors, metal ion detection, and optoelectronics. Lignin, being the most abundant aromatic biomass material in nature, is one of the ideal materials for preparing CQDs. However, most CQDs prepared using lignin as a precursor currently employ organic or inorganic acids as dopants, which contradicts the principles of green chemistry and hinders widespread adoption in the industry, thus limiting their applications. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] Therefore, the purpose of this invention is to provide a lignin carbon quantum dot fluorescent bamboo fiber, its preparation method, and its application. Bamboo cells are separated and processed to obtain bamboo fibers with high strength. Using alkali lignin as a carbon source, hydrogen peroxide as an oxidant, and a small amount of p-phenylenediamine as a nucleating agent, lignin carbon quantum dots emitting yellow-green fluorescence are successfully prepared using a hydrothermal method. These lignin carbon quantum dots are then combined with bamboo fibers to prepare fluorescent carbon quantum dot fluorescent bamboo fibers, which have certain application prospects in industries such as anti-counterfeiting labels and smart textiles.

[0006] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0007] A method for preparing lignin carbon quantum dot fluorescent bamboo fiber, comprising:

[0008] S1. Select bamboo strip samples after rough planing, dry them at 80-90℃ until the moisture content is below 30%, and clean the surface with anhydrous ethanol and acetone in sequence, then set them aside for later use.

[0009] S2. Mix choline chloride, oxalic acid and deionized water and stir evenly to prepare delignification aqueous solution. Soak the bamboo strip sample treated in step S1 in delignification aqueous solution and heat in a water bath at 80℃-90℃ for 6-8 hours to perform delignification treatment.

[0010] S3. Take out the bamboo strip sample that has undergone delignification treatment in step S2, rinse it several times with distilled water, and then freeze-dry it and mechanically separate it to obtain delignified bamboo fiber.

[0011] S4. Weigh out alkali lignin and o-phenylenediamine separately, and dissolve them completely in hydrogen peroxide solution. Transfer the mixed solution to a reaction vessel with a polytetrafluoroethylene liner, and heat it in an oven at 160°C for 8 hours. Centrifuge the mixed solution in the reaction vessel, freeze-dry the resulting supernatant to obtain powder, and redissolve it in anhydrous ethanol to prepare a carbon quantum dot impregnation solution with yellow-green fluorescence.

[0012] S5. The delignified bamboo fiber obtained in step S3 is impregnated in the carbon quantum dot impregnation solution prepared in step S4, and then placed in a vacuum drying kettle for negative pressure impregnation for 30 minutes.

[0013] S6. Weigh polyvinyl alcohol powder and dissolve it in distilled water to obtain polyvinyl alcohol gel. Take out the delignified bamboo fiber impregnated with carbon quantum dots prepared in step S5, and uniformly coat its surface with the prepared polyvinyl alcohol gel. Dry at room temperature.

[0014] In a preferred embodiment of the preparation method of lignin carbon quantum dot fluorescent bamboo fiber according to the present invention, in step S1, the bamboo strip sample is 3-4 year old moso bamboo, and after removing the bamboo green and bamboo yellow, it is roughly cut into dimensions of 100mm in length, 20mm in width and 8mm in height, and the absolute moisture content after drying is 11%. The cleaning conditions for anhydrous ethanol and acetone are ultrasonic vibration, and the cleaning time is 2 minutes for each.

[0015] In a preferred embodiment of the method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to the present invention, in step S2, the molar ratio of choline chloride and oxalic acid is 1:10, and the amount of deionized water added is 10% of the total mass of the mixed solution.

[0016] In a preferred embodiment of the method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to the present invention, the water bath temperature in step S2 is 85°C.

[0017] In a preferred embodiment of the method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to the present invention, in step S4, the alkali lignin is low-sulfonated lignin, the mass fraction of hydrogen peroxide solution is 30%, and the mass-to-volume ratio of lignin, o-phenylenediamine and hydrogen peroxide is 3g:0.5g:80mL.

[0018] In a preferred embodiment of the preparation method of lignin carbon quantum dot fluorescent bamboo fiber according to the present invention, in step S4, the centrifugation conditions are 10,000 rpm for 10 minutes, the freeze-drying temperature is -40°C, the freeze-drying time is 72 h, and the mass-to-volume ratio of the carbon quantum dot powder to anhydrous ethanol is 0.005 g / mL.

[0019] In a preferred embodiment of the method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to the present invention, in step S6, the mass of polyvinyl alcohol weighed is 5g and the mass of distilled water is 80mL, wherein the weight-average molecular weight of the polyvinyl alcohol used is 1750.

[0020] In a preferred embodiment of the method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to the present invention, in step S6, polyvinyl alcohol gel is uniformly coated on the surface of bamboo fiber impregnated with carbon quantum dots, wherein the coating amount is 1g gel per 5g bamboo fiber, and the room temperature drying time is 24h.

[0021] Fluorescent bamboo fiber prepared by a method for preparing lignin carbon quantum dot fluorescent bamboo fiber.

[0022] A fluorescent bamboo fiber used in anti-counterfeiting labels and smart textiles.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. Bamboo cells were separated to obtain high-strength bamboo fibers. Using alkali lignin as a carbon source, hydrogen peroxide as an oxidant, and a small amount of p-phenylenediamine as a nucleating agent, lignin carbon quantum dots emitting yellow-green fluorescence were successfully prepared by hydrothermal method. These lignin quantum dots were then combined with bamboo fibers to prepare fluorescent carbon quantum dot fluorescent bamboo fibers, which have certain application prospects in industries such as anti-counterfeiting labels and smart textiles.

[0025] 2. This invention uses non-toxic hydrogen peroxide to oxidize alkali lignin. In the hydrothermal reaction, alkali lignin is more fully decomposed into small molecule compounds, and yellow-green fluorescent carbon quantum dots are prepared accordingly. This invention simplifies the purification steps of carbon quantum dots, and the obtained carbon quantum dots can be effectively purified by centrifugation alone.

[0026] 3. This invention uses delignified bamboo fiber as a dispersion carrier and utilizes the abundant free hydroxyl groups on the surface of bamboo fiber to adsorb carbon quantum dots in order to solve the problem of solid-state fluorescence quenching of carbon quantum dots and realize their solid-state luminescence. This invention uses polyvinyl alcohol to coat the surface of bamboo fiber, which can form a certain "confining effect" on carbon quantum dots, which helps to realize the room temperature phosphorescence performance of carbon quantum dot fluorescent bamboo fiber. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0028] Figure 1 This is a flowchart of a method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to the present invention. Detailed Implementation

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0032] This invention provides a lignin carbon quantum dot fluorescent bamboo fiber, its preparation method, and its application. Bamboo cells are separated and processed to obtain bamboo fibers with high strength. Using alkali lignin as the carbon source, hydrogen peroxide as the oxidant, and a small amount of p-phenylenediamine as the nucleating agent, lignin carbon quantum dots emitting yellow-green fluorescence are successfully prepared using a hydrothermal method. These lignin carbon quantum dots are then combined with bamboo fibers to prepare fluorescent carbon quantum dot fluorescent bamboo fibers, which have certain application prospects in industries such as anti-counterfeiting labels and smart textiles.

[0033] Example 1

[0034] like Figure 1 As shown, the preparation method of this lignin carbon quantum dot fluorescent bamboo fiber is as follows:

[0035] S1. Select 3-year-old bamboo strips with rough planing of 100mm*20mm*8mm. The bamboo strips should not contain bamboo nodes and should not have obvious defects on the surface. Place them in an 80℃ forced-air drying oven and dry them until the absolute moisture content is 11%. Take out the bamboo strips and place them in anhydrous ethanol and acetone for ultrasonic cleaning. The cleaning time is 2 minutes for each.

[0036] S2. Mix 70g (0.5mol) choline chloride with 450g (5mol) oxalic acid, add 52g distilled water, mix and stir evenly to prepare delignification solution. Weigh 9.6g of the bamboo strip sample dried in step S1 and soak it in delignification solution. Heat in a water bath at 80℃ for 6h to delignify until the bamboo strip sample turns white.

[0037] S3. Take out the bamboo sample that has undergone delignification treatment in step S2, rinse it three times with distilled water and freeze-dry it at -40℃ for 72 hours. Remove the freeze-dried sample and manually shake and vibrate it to separate the bamboo fiber cells.

[0038] S4. Weigh 3g of alkali lignin and 0.5g of p-phenylenediamine, add them to 80ml of 30wt% hydrogen peroxide solution and stir for 5 minutes. Then transfer the mixture to a reaction vessel lined with polytetrafluoroethylene and heat it in an oven at 160℃ for 8 hours. Take out the mixed solution from the reaction vessel and place it in a centrifuge for solid-liquid separation. The centrifugation speed is 10000 rpm and the centrifugation time is 10 minutes. Freeze-dry the supernatant obtained by centrifugation to obtain powder. Take 0.05g of the freeze-dried powder and redissolve it in 10mL of anhydrous ethanol to prepare a carbon quantum dot impregnation solution with yellow-green fluorescence.

[0039] S5. The bamboo fiber separated in step S3 is impregnated in 10 mL of carbon quantum dot impregnation solution prepared in step S4, and then placed in a vacuum drying kettle for negative pressure impregnation for 30 min.

[0040] S6. Weigh 5g of polyvinyl alcohol, dissolve it in 80mL of distilled water, and heat and stir at 90℃ for 10 minutes to obtain polyvinyl alcohol gel. Take out the delignified bamboo fiber impregnated with carbon quantum dot impregnation solution prepared in step S5, and coat it evenly with polyvinyl alcohol gel (the weight average molecular weight of polyvinyl alcohol is 1750). Control the coating amount to 1g gel / 5g bamboo fiber, and dry at room temperature for 24h.

[0041] Example 2

[0042] like Figure 1 As shown, the preparation method of this lignin carbon quantum dot fluorescent bamboo fiber is as follows:

[0043] S1. Select 3-year-old bamboo strips with rough planing of 100mm*20mm*8mm. The bamboo strips should not contain bamboo nodes and should not have obvious defects on the surface. Place them in an 85℃ forced-air drying oven and dry them until the absolute moisture content is 11%. Take out the bamboo strips and place them in anhydrous ethanol and acetone for ultrasonic cleaning for 2 minutes each.

[0044] S2. Mix 70g (0.5mol) choline chloride with 450g (5mol) oxalic acid, add 52g distilled water, mix and stir evenly to prepare delignification solution. Weigh 9.6g of the bamboo strip sample dried in step S1 and soak it in delignification solution. Heat in a water bath at 85℃ for 6h to delignify until the bamboo strip sample turns white.

[0045] S3. Take out the bamboo sample that has undergone delignification treatment in step S2, rinse it three times with distilled water and freeze-dry it at -40℃ for 72 hours. Remove the freeze-dried sample and manually shake and vibrate it to separate the bamboo fiber cells.

[0046] S4. Weigh 3g of alkali lignin and 0.5g of p-phenylenediamine, add them to 80ml of 30wt% hydrogen peroxide solution and stir for 5 minutes. Then transfer the mixture to a reaction vessel lined with polytetrafluoroethylene and heat it in an oven at 160℃ for 8 hours. Take out the mixed solution from the reaction vessel and place it in a centrifuge for solid-liquid separation. The centrifugation speed is 10000 rpm and the centrifugation time is 10 minutes. Freeze-dry the supernatant obtained by centrifugation to obtain powder. Take 0.05g of the freeze-dried powder and redissolve it in 10mL of anhydrous ethanol to prepare a carbon quantum dot impregnation solution with yellow-green fluorescence.

[0047] S5. The bamboo fiber separated in step S3 is impregnated in 10 mL of carbon quantum dot impregnation solution prepared in step S4, and then placed in a vacuum drying kettle for negative pressure impregnation for 30 min.

[0048] S6. Weigh 5g of polyvinyl alcohol, dissolve it in 80mL of distilled water, and heat and stir at 90℃ for 10 minutes to obtain polyvinyl alcohol gel. Take out the delignified bamboo fiber impregnated with carbon quantum dot impregnation solution prepared in step S5, and coat it evenly with polyvinyl alcohol gel (the weight average molecular weight of polyvinyl alcohol is 1750). Control the coating amount to 1g gel / 5g bamboo fiber, and dry at room temperature for 24h.

[0049] Example 3

[0050] like Figure 1 As shown, the preparation method of this lignin carbon quantum dot fluorescent bamboo fiber is as follows:

[0051] S1. Select 3-year-old bamboo strips with rough planing of 100mm*20mm*8mm. The bamboo strips should not contain bamboo nodes and should not have obvious defects on the surface. Place them in a 90℃ forced-air drying oven and dry them until the absolute moisture content is 11%. Take out the bamboo strips and place them in anhydrous ethanol and acetone for ultrasonic cleaning. The cleaning time is 2 minutes for each.

[0052] S2. Mix 70g (0.5mol) choline chloride with 450g (5mol) oxalic acid, add 52g distilled water, mix and stir evenly to prepare delignification solution. Weigh 9.6g of the bamboo strip sample dried in step S1 and soak it in delignification solution. Heat in a 90℃ water bath for 6h to delignify until the bamboo strip sample turns white.

[0053] S3. Take out the bamboo sample that has undergone delignification treatment in step S2, rinse it three times with distilled water and freeze-dry it at -40℃ for 72 hours. Remove the freeze-dried sample and manually shake and vibrate it to separate the bamboo fiber cells.

[0054] S4. Weigh 3g of alkali lignin and 0.5g of p-phenylenediamine, add them to 80ml of 30wt% hydrogen peroxide solution and stir for 5 minutes. Then transfer the mixture to a reaction vessel lined with polytetrafluoroethylene and heat it in an oven at 160℃ for 8 hours. Take out the mixed solution from the reaction vessel and place it in a centrifuge for solid-liquid separation. The centrifugation speed is 10000 rpm and the centrifugation time is 10 minutes. Freeze-dry the supernatant obtained by centrifugation to obtain powder. Take 0.05g of the freeze-dried powder and redissolve it in 10mL of anhydrous ethanol to prepare a carbon quantum dot impregnation solution with yellow-green fluorescence.

[0055] S5. The bamboo fiber separated in step S3 is impregnated in 10 mL of carbon quantum dot impregnation solution prepared in step S4, and then placed in a vacuum drying kettle for negative pressure impregnation for 30 min.

[0056] S6. Weigh 5g of polyvinyl alcohol, dissolve it in 80mL of distilled water, and heat and stir at 90℃ for 10 minutes to obtain polyvinyl alcohol gel. Take out the delignified bamboo fiber impregnated with carbon quantum dot impregnation solution prepared in step S5, and coat it evenly with polyvinyl alcohol gel (the weight average molecular weight of polyvinyl alcohol is 1750). Control the coating amount to 1g gel / 5g bamboo fiber, and dry at room temperature for 24h.

[0057] Comparative tests showed that the bamboo fiber prepared in Example 2 exhibited yellow-green fluorescence under 395nm ultraviolet light excitation and had a fluorescence afterglow of 0.5-1 seconds. Therefore, the prepared carbon quantum dot quantum fluorescence performance was stable, and the fluorescent bamboo fiber could be used in anti-counterfeiting labels and fluorescent clothing.

[0058] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing lignin carbon quantum dot fluorescent bamboo fiber, characterized in that, The preparation method comprises the following steps: S1, selecting a rough planed bamboo strip sample, drying it at 80-90℃ until the moisture content is less than 30%, and then cleaning the surface with anhydrous ethanol and acetone in sequence, and preparing it for use; S2, mixing choline chloride, oxalic acid and deionized water and stirring them uniformly to prepare a delignification aqueous solution, immersing the bamboo strip sample treated in step S1 in the delignification aqueous solution, and delignifying it by heating in a water bath at 80-90℃ for 6-8h; S3, taking out the bamboo strip sample delignified in step S2, rinsing it with distilled water several times, and then freeze-drying it to obtain delignified bamboo fibers by mechanical separation; S4, respectively weighing alkali lignin and p-phenylenediamine, and dissolving them in hydrogen peroxide solution, transferring the mixed solution into a reaction kettle with a polytetrafluoroethylene liner, heating it in an oven at 160℃ for 8h, centrifuging the mixed solution in the reaction kettle, freeze-drying the obtained centrifugal supernatant to obtain a powder, and re-dissolving it in anhydrous ethanol to prepare a carbon quantum dot impregnating solution with yellow-green fluorescence; S5, immersing the delignified bamboo fibers prepared in step S3 in the carbon quantum dot impregnating solution prepared in step S4, and placing them in a vacuum drying oven for negative pressure impregnation for 30min; S6, weighing polyvinyl alcohol powder and dissolving it in distilled water to obtain a polyvinyl alcohol gel, taking out the delignified bamboo fibers impregnated with carbon quantum dots prepared in step S5, and uniformly coating the surface of the delignified bamboo fibers with the prepared polyvinyl alcohol gel, and drying it at room temperature. In step S2, the molar ratio of choline chloride to oxalic acid is 1:10, and the amount of deionized water added is 10% of the total mass of the mixed solution.

2. The method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to claim 1, characterized in that, In step S1, the bamboo strip sample is 3-4 year old bamboo, and after removing the bamboo green and bamboo yellow, it is roughly planed into a size of 100mm, 20mm and 8mm in length, width and height respectively, the absolute moisture content after drying is 11%, and the conditions for cleaning with anhydrous ethanol and acetone are ultrasonic oscillation, and the cleaning time is 2 minutes respectively.

3. The method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to claim 1, characterized in that, In step S2, the water bath temperature is 85℃.

4. The method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to claim 1, characterized in that, In step S4, the alkali lignin is low-sulfonated lignin, the mass fraction of hydrogen peroxide solution is 30%, and the mass and volume ratio of lignin, p-phenylenediamine and hydrogen peroxide is 3g:0.5g:80mL.

5. The method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to claim 1, characterized in that, In step S4, the centrifugation conditions are 10000r / min for 10min, the freeze-drying temperature is-40℃, the freeze-drying time is 72h, and the mass and volume ratio of carbon quantum dot powder to anhydrous ethanol is 0.005g / mL.

6. The method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to claim 1, characterized in that, In step S6, the mass of polyvinyl alcohol used is 5g, and the distilled water is 80mL, wherein the weight average molecular weight of the polyvinyl alcohol used is 1750.

7. The method for preparing lignin carbon quantum dot fluorescent bamboo fiber according to claim 1, characterized in that, In step S6, the surface of the bamboo fibers impregnated with carbon quantum dots is uniformly coated with polyvinyl alcohol gel, wherein the coating amount is 1g of gel per 5g of bamboo fibers, and the room temperature drying time is 24h.

8. A fluorescent bamboo fiber prepared by the preparation method of the lignin carbon quantum dot fluorescent bamboo fiber according to any one of claims 1-7.

9. The fluorescent bamboo fiber according to claim 8, applied to the field of anti-counterfeiting identification and intelligent textiles.

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