Aldehyde-ketone synthetic carbon dots with high emulsification level and excellent wettability and preparation method of aldehyde-ketone synthetic carbon dots

Abstract

The invention discloses an aldehyde ketone synthetic carbon dot with high emulsification level and excellent wettability and a preparation method thereof, and belongs to the technical field of two-dimensional interface materials. According to the invention, acetaldehyde and acetone are used as carbon sources, the carbon dot material with high emulsification level and excellent wettability is prepared by controlling the reaction time, the aldehyde ketone type and the aldehyde ketone ratio, and the prepared carbon dot material is applied to emulsification of a toluene organic solvent to obtain an emulsion system with high emulsification level. Compared with a hydrothermal method, a solvothermal method is adopted, reaction kettle heating is not needed, and energy consumption is reduced. The prepared carbon dots have extremely high adaptability in an emulsification system, and the unique surface chemical characteristics of the carbon dots enable the carbon dots to form a high-stability emulsification layer on an oil-water interface, so that the emulsification effect is effectively enhanced. The aldehyde ketone carbon dot material obtained by the invention is uniform in size and high in dispersity, can meet the emulsification requirements under different oil phase conditions, and is extremely low in cost and simple in preparation process.

Description

Technical Field

[0001] The present invention belongs to the technical field of two-dimensional interface materials, and particularly relates to aldehyde-ketone synthesized carbon dots with high emulsification level and excellent wettability and a preparation method thereof. Background Art

[0002] Emulsification technology is widely used in food, cosmetics, medicine, and materials engineering. However, existing emulsifiers have defects such as high toxicity, environmental pollution, and insufficient stability, and there is an urgent need to develop more environmentally friendly and efficient alternatives. Compared with traditional emulsifiers, carbon dot materials have the advantages of non-toxicity and biodegradability. At the same time, their surface properties and particle size distribution can be flexibly regulated by the nitrogen doping ratio and preparation conditions. This enables carbon dot materials to not only perform excellently in fields such as food and cosmetics that require high safety, but also demonstrate efficient and lasting performance in industrial emulsification and materials synthesis. In addition, the interfacial film formed by them can significantly reduce the occurrence of emulsion stratification, aggregation, and precipitation, improving the long-term stability of the system.

[0003] In addition, the preparation of carbon dot materials has significant advantages such as low cost, simple process, and environmental friendliness. Green raw material selection: Low-cost resources such as industrial waste and biomass can be used as raw materials for the preparation of carbon dots, reducing production costs; Efficient preparation process: Techniques such as low-energy hydrothermal method and microwave method are adopted to simplify the preparation process and facilitate large-scale application; Small environmental burden: Carbon dots have excellent biodegradability, reducing the cumulative pollution problem of emulsifiers in the environment.

[0004] As a new type of emulsifier, the application of carbon dot materials not only solves the safety and environmental protection problems of existing emulsifiers, but also provides a more superior alternative solution. Its application prospects in green chemistry, food industry, and functional materials development are broad, providing a new technical path and idea for realizing sustainable development.

[0005] Currently, the reported preparation methods of carbon dot materials mainly include two methods: "top-down" and "bottom-up". The "top-down" method decomposes large-sized carbon materials into nanoscale carbon dot materials through methods such as laser etching and chemical oxidation. The "bottom-up" method generates carbon dot materials from small molecule organic precursors through methods such as hydrothermal method, solvothermal method, and pyrolysis method. Among them, the "bottom-up" method has a higher purity for preparing carbon dot materials. The existing patent CN119797336A discloses a method for preparing carbon dots, using acetaldehyde as a carbon source, condensing under the catalysis of NaOH, and finally obtaining a product with a certain emulsification effect, and the emulsification rate can reach 80%. Summary of the Invention

[0006] The object of the present invention is to provide aldehyde-ketone synthesized carbon dots with high emulsification level and excellent wettability and a preparation method thereof.

[0007] The present invention uses acetaldehyde and acetone as carbon sources, and prepares carbon dot materials with a high emulsification level and excellent wettability by controlling the reaction time, the types of aldehydes and ketones, and the ratio of aldehydes to ketones. The prepared carbon dot materials are applied to the emulsification of toluene organic solvents to obtain an emulsion system with a high emulsification level. The present invention adopts the solvothermal method. Compared with the hydrothermal method, it does not require the heating of a reaction kettle and reduces energy consumption. The carbon dots prepared by the present invention have extremely high adaptability in the emulsification system. Their unique surface chemical properties enable them to form a highly stable emulsifying layer at the oil-water interface, effectively enhancing the emulsification effect. The aldehyde-ketone carbon dot materials obtained by the present invention are uniform in size and have a high dispersion degree, can meet the emulsification requirements under different oil phase conditions, and have extremely low costs and simple manufacturing processes.

[0008] The present invention proposes a new preparation method. Compared with the existing patent CN119797336A, by adding acetone, the enolate anion formed by acetaldehyde under alkaline conditions can attack the carbonyl carbon of acetone, and further undergo aldol condensation. The finally obtained product also has better wettability. The emulsification rate is increased from 80% to 85%, and the stabilization time can reach several months or more, far higher than the situation in this patent where it can only be stable for about half a month.

[0009] The preparation method of aldehyde-ketone synthetic carbon dots with a high emulsification level and excellent wettability according to the present invention is as follows: (1) Prepare a 5 - 10 M NaOH aqueous solution, stir for 20 - 30 minutes and then let it stand. (2) Slowly dropwise add the NaOH aqueous solution prepared in step (1) into an aqueous acetaldehyde solution and an acetone solution with a mass fraction of 30 - 50%, finish dropping within 20 - 30 minutes and stir evenly. (3) Under room temperature conditions, stir the system obtained in step (2) for 2 - 5 h to obtain a dark brown paste solution. (4) Dropwise add a hydrochloric acid solution to the dark brown paste solution obtained in step (3), adjust the pH of the solution to neutral, and then continuously stir for 4 - 12 h until the system is a yellowish brown solution. (5) Centrifuge the yellowish brown solution obtained in step (4) at a speed of 12000 - 13000 rpm for 3 - 5 minutes, remove the supernatant after centrifugation, and retain the precipitate. (6) Add deionized water to the precipitate obtained in step (5), disperse it evenly by ultrasonic treatment, remove the supernatant after centrifugation, and retain the precipitate; repeat the operations of "adding deionized water to the precipitate - ultrasonic dispersion - centrifugation - retaining the precipitate" 3 - 5 times to obtain a yellowish brown precipitate. (7) Freeze-dry the yellowish brown precipitate obtained in step (6) with liquid nitrogen to obtain yellow carbon dot materials. (8) Disperse 1-2 g of the yellow carbon dot material obtained in step (7) in 10-20 mL of methanol, add 1-2 g of potassium methoxide and 0.5-2 g of nitrogen source, and stir until there is no solid precipitate; adding potassium methoxide provides an alkaline environment to enhance nucleophilicity, thus successfully introducing amino groups; (9) Heat and stir the system obtained in step (8) at 70-90 °C for 30-60 minutes; (10) Centrifuge the system obtained in step (9) at a speed of 10000-15000 rpm for 2-5 minutes, remove the supernatant, retain the precipitate and dry it to obtain the aldehyde-ketone synthesized carbon dots with high emulsification level and excellent wettability.

[0010] Further, in step (2), the volume ratio of the NaOH aqueous solution to the aqueous acetaldehyde solution and the acetone solution is 1:1-3:3-5, the concentration of the hydrochloric acid solution in step (4) is 1-3 M, the freeze-drying conditions in step (7) are a temperature of -70 to -60 °C and a vacuum degree < 10 Pa, the nitrogen source in step (8) is urea, thiourea, lysine, glycine and citrulline, and in step (10), it is vacuum dried at 60-80 °C for 15-30 hours.

[0011] Add the aldehyde-ketone carbon dot material obtained in step (10) to deionized water and disperse it by ultrasonic wave to obtain an aldehyde-ketone carbon dot material dispersion. Then, mix the obtained aldehyde-ketone carbon dot material dispersion with toluene in a volume ratio of 1:1 and oscillate. After oscillation, quickly transfer it to a colorimetric tube, and measure its emulsification rate after standing for 24 h to detect its amphiphilic emulsification performance; Different gradients of oil phases with HLB values (hydrophilic-lipophilic balance values) were prepared using cottonseed oil and turpentine. Then, the aldehyde-ketone carbon dot material dispersion was mixed with oil phases with different gradient HLB values, and emulsions were prepared after ultrasonic oscillation. After standing for 24 h, the emulsification rate and HLB value were obtained by observing the emulsification results.

[0012] The technical solution of the present invention can rapidly synthesize a large amount of nano-scale aldehyde-ketone carbon dot materials with amphiphilic emulsification effects under mild reaction conditions. The obtained aldehyde-ketone carbon dot materials are uniform in size and have a high degree of dispersion, can meet the emulsification requirements under different oil phase conditions, and have extremely low costs and simple manufacturing processes. Description of the Drawings

[0013] Figure 1 : Optical photograph of the aldehyde-ketone carbon dot material obtained in Example 1; Figure 2 : Transmission electron microscope photograph of the aldehyde-ketone carbon dot material obtained in Example 1; Figure 3 : XRD pattern of the aldehyde-ketone carbon dot material obtained in Example 1; Figure 4 : Infrared diagram of the aldehyde-ketone carbon dot material obtained in Example 1; Figure 5 : Optical photograph of the emulsifying effect of the aldehyde-ketone carbon dot material obtained in Example 1; Figure 6 : Emulsifying bubble diagram of the aldehyde-ketone carbon dot material obtained in Example 1 by a Leica electron microscope; Figure 7 : Water contact angle picture of the aldehyde-ketone carbon dot material obtained in Example 1; Figure 8 : Oil contact angle picture of the aldehyde-ketone carbon dot material obtained in Example 1; Figure 9 : Optical photograph of the oil phase with a gradient HLB value after the dispersion of the aldehyde-ketone carbon dot material obtained in Example 1; Figure 10 : Optical pictures of the emulsifying effects of Examples 1-9; Figure 11 : Emulsifying bubble diagrams of Examples 1-9 by a Leica electron microscope; Table 1: Mass table of cottonseed oil and turpentine required to configure different gradient HLB values Detailed implementation manners

[0014] To make the objectives, technical solutions, and advantageous effects of the embodiments of the present invention clearer, the embodiments will be described in more detail and completely below. It should be noted that the following described embodiments are not all embodiments, but only the embodiments of the preferred invention conditions of the present invention. The reagents and instruments used in the embodiments can all be purchased through normal commercial channels. Based on the embodiments of the present invention, those of ordinary skill in the art can directly obtain this embodiment without creative activities, which belongs to the scope protected by the present invention.

[0015] Example 1: (1) Prepare 10 mL of 10 M NaOH aqueous solution, stir for 20 minutes and then let it stand; (2) Slowly add the NaOH aqueous solution prepared in step (1) drop by drop to 10 mL of 40% by mass aqueous acetaldehyde solution and 30 mL of acetone solution, and finish dropping within 20 minutes and stir evenly; (3) Under room temperature conditions, stir the system obtained in step (2) for 3 h to obtain a dark brown paste solution; (4) Prepare 30 mL of 1 M hydrochloric acid solution; add the obtained hydrochloric acid solution drop by drop to the dark brown paste solution obtained in step (3), adjust the solution to pH = 7.0, and then continuously stir for 8 h to obtain a yellowish-brown solution; (5) Centrifuge the yellowish-brown solution obtained in step (4) at a speed of 13000 rpm for 5 minutes, remove the supernatant after centrifugation, and retain the precipitate; (6) Add deionized water to the precipitate obtained in step (5), ultrasonically disperse it evenly, remove the supernatant after centrifugation, and retain the precipitate; repeat the operations of "adding deionized water to the precipitate - ultrasonic dispersion - centrifugation - retaining the precipitate" 4 more times to obtain a brownish-yellow precipitate; (7) Freeze-dry the brownish-yellow precipitate obtained in step (6) using liquid nitrogen extraction (-65 °C, vacuum degree < 10 Pa) to obtain 2.5 g of orange-yellow carbon dot material; (8) Disperse 1 g of the orange-yellow carbon dot material obtained in step (7) in 10 mL of methanol, add 1 g of potassium methoxide and 1 g of urea, and stir for 10 minutes until there is no solid precipitate; (9) Heat and stir the system obtained in step (8) at 80 °C for 30 minutes; (10) Centrifuge the system obtained in step (9) at a speed of 13000 rpm for 3 minutes, remove the supernatant, retain the precipitate and vacuum dry it at 80 °C for 24 hours to obtain 0.8 g of aldehyde-ketone synthesized carbon dot material with a high emulsification level and excellent wettability.

[0016] Take 20 mg of the carbon dot material and add it to 5 mL of deionized water, and ultrasonically treat it for 10 minutes (frequency 40 Khz) to obtain a carbon dot material dispersion. Add the obtained carbon dot material dispersion to 5 mL of toluene to form a water-oil system, then place it in a constant temperature shaker and oscillate it at 300 rpm for 1 hour, and finally transfer it to a glass bottle, seal it and let it stand for more than 24 hours. By measuring the height H of the emulsion layer 乳 and the total height H of the oil-water system 总 , calculate the emulsification rate according to the formula emulsification rate = (H 乳 / H 总 ) * 100% to be 85%; observe the average diameter of the formed emulsion bubbles to be 45 μm through a Leica electron microscope. Add the obtained carbon dot material dispersion to 5 mL of an oil phase with a gradient HLB value (HLB = 7 - 13), mix and ultrasonically treat it for 30 minutes (frequency 40 Khz), let it stand for 24 hours, and observe that the HLB value corresponding to the system with the highest stability and emulsion layer height is 9 - 10.

[0017] Figure 1 is a photo of the appearance of the solid material of the aldehyde-ketone carbon dot material, which is a yellow powder. Figure 2 is its transmission electron microscope photo, from which it can be seen that the obtained aldehyde-ketone carbon dot material has an average particle size and a diameter of 2 - 4 nm. Figure 3 is the X-ray diffraction (XRD) pattern of the aldehyde-ketone carbon dot material, from which it can be seen that the aldehyde-ketone carbon dot material has a broad peak at θ = 20 degrees, corresponding to the highly graphitized structure of the aldehyde-ketone carbon dot material. Figure 4 is the infrared (IR) spectrum of the aldehyde-ketone carbon dot material, from which it can be seen that the carbon dot material has rich functional groups such as hydroxyl, carboxyl, alkyl, and epoxy groups. Figure 5It is the emulsification effect diagram of aldehyde-ketone carbon dot materials. In the water / toluene system, the formed emulsified layer occupies the entire toluene phase and part of the water phase (the toluene phase is on the top and the water phase is on the bottom), forming a stable Pickering emulsion. Figure 6 It is the emulsified bubble diagram of the water / toluene system added with aldehyde-ketone carbon dot materials by a Leica electron microscope. It can be seen that the formed emulsified bubbles are of uniform size, and the average diameter is 45μm. Figure 7 It is the water contact angle photo. It can be seen that aldehyde-ketone carbon dots have a good hydrophilic effect. Figure 8 It is the oil (hexadecane) contact angle photo. It can be seen that aldehyde-ketone carbon dots have a good lipophilic effect, indicating that the aldehyde-ketone carbon dot materials have excellent wettability. Figure 9 It is the optical photo of the carbon dot material dispersion in the oil phase with gradient HLB values. The numbers in the figure represent the corresponding HLB values. It can be clearly seen that the emulsified layer heights of numbers 9 and 10 are the highest and the stability effect is the best, indicating that the HLB value range of the aldehyde-ketone carbon dot materials is 9-10. Figure 10 It is the optical photo of the emulsification effect of Examples 1-9. The emulsification rate of the examples can be calculated. Among them, the best effect is in Example 1, with an emulsification rate of 85%, and the stable duration can reach several months. Figure 11 It is the emulsified bubble diagram of the Leica electron microscope of Examples 1-9. It can be observed that the emulsified bubble size distribution of the emulsification system in Example 1 is extremely narrow and the average particle size is the smallest, which is 45μm. The emulsified layer formed in Example 7 is extremely unstable and the emulsified bubbles quickly break. The emulsified bubbles formed in Example 9 are very dense but the size distribution is very wide and gradually break and dissipate after 1h.

[0018] Example 2: Steps (1)-(7) are the same as in Example 1, and 2.5 g of orange-yellow carbon dot materials are obtained; (8) Disperse 1 g of the orange-yellow carbon dot materials obtained in step (7) in 10 mL of methanol, add 1 g of potassium methoxide and 1 g of lysine, and stir for 10 minutes until there is no solid precipitation; (9) Heat and stir the system obtained in step (8) at 80 °C for 30 minutes; (10) Centrifuge the system obtained in step (9) at 13000 rpm for 5 minutes, remove the supernatant, retain the precipitate and vacuum dry it at 60 °C for 24 hours to obtain 0.79 g of carbon dot materials with a diameter of 6-15 nm, an emulsification rate of 40%, an average diameter of emulsified bubbles of 100μm, and the emulsified layer is stable and does not break.

[0019] Example 3: Steps (1)-(7) are the same as in Example 1, and 2.5 g of orange-yellow carbon dot materials are obtained; (8) Disperse 1 g of the orange-yellow carbon dot material obtained in step (7) in 10 mL of methanol, add 1 g of potassium methoxide and 1 g of thiourea, and stir for 10 minutes until there is no solid precipitate; (9) Heat and stir the system obtained in step (8) at 80 °C for 30 minutes; (10) Centrifuge the system obtained in step (9) at 13,000 rpm for 5 minutes, remove the supernatant, retain the precipitate and vacuum dry it at 60 °C for 24 hours to obtain 0.56 g of carbon dot material with a diameter of 20 - 28 nm, an emulsification rate of 58%, an average diameter of emulsification bubbles of 80 μm, and a stable emulsification layer without demulsification.

[0020] Example 4: Steps (1) to (7) are the same as in Example 1 to obtain 2.5 g of orange-yellow carbon dot material; (8) Disperse 1 g of the orange-yellow carbon dot material obtained in step (7) in 10 mL of methanol, add 1 g of potassium methoxide and 1 g of glycine, and stir for 10 minutes until there is no solid precipitate; (9) Heat and stir the system obtained in step (8) at 80 °C for 30 minutes; (10) Centrifuge the system obtained in step (9) at 13,000 rpm for 5 minutes, remove the supernatant, retain the precipitate and vacuum dry it at 60 °C for 24 hours to obtain 0.61 g of carbon dot material with a diameter of 30 - 40 nm, an emulsification rate of 56%, an average diameter of emulsification bubbles of 80 μm, and a stable emulsification layer without demulsification.

[0021] Example 5: Steps (1) to (7) are the same as in Example 1 to obtain 2.5 g of orange-yellow carbon dot material; (8) Disperse 1 g of the orange-yellow carbon dot material obtained in step (7) in 10 mL of methanol, add 1 g of potassium methoxide and 1 g of citrulline, and stir for 10 minutes until there is no solid precipitate; (9) Heat and stir the system obtained in step (8) at 80 °C for 30 minutes; (10) Centrifuge the system obtained in step (9) at 13,000 rpm for 5 minutes, remove the supernatant, retain the precipitate and vacuum dry it at 80 °C for 24 hours to obtain 0.77 g of carbon dot material with a diameter of 12 - 15 nm, an emulsification rate of 45%, an average diameter of emulsification bubbles of 130 μm, and a stable emulsification layer without demulsification.

[0022] Example 6: Take 10 mL of an aqueous acetaldehyde solution with a mass fraction of 40%, 30 mL of acetone solution, and 20 mL of ammonia water (concentration 27%), mix them, react at 20 °C for 3 hours, add 30 mL of 1 M hydrochloric acid solution, adjust to neutral pH, and the remaining operations are the same as in Example 1. No carbon dot material is produced after step (7).

[0023] Example 7: Steps (1) to (7) are the same as in Example 1 to obtain 2.5 g of orange-yellow carbon dot material; (8) Disperse 1 g of the orange-yellow carbon dot material obtained in step (7) in 10 mL of methanol, add 1 g of potassium methoxide and 1 g of aniline, and stir for 10 minutes until there is no solid precipitation; (9) Heat and stir the system obtained in step (8) at 80 °C for 30 minutes; (10) Centrifuge the system obtained in step (9) at 13000 rpm for 5 minutes, remove the supernatant, retain the precipitate and vacuum dry it at 80 °C for 24 hours to obtain 1.1 g of carbon dot material with a diameter of 20 - 25 nm, very poor emulsifying effect, unstable emulsion layer, and rapid demulsification.

[0024] Example 8: Steps (1) to (7) are the same as in Example 1 to obtain 2.5 g of orange-yellow carbon dot material; (8) Disperse 1 g of the orange-yellow carbon dot material obtained in step (7) in 10 mL of methanol, add 1 g of potassium methoxide and 1 g of pyridine, and stir for 10 minutes until there is no solid precipitation; (9) Heat and stir the system obtained in step (8) at 80 °C for 30 minutes; (10) Centrifuge the system obtained in step (9) at 13000 rpm for 5 minutes, remove the supernatant, retain the precipitate and vacuum dry it at 60 °C for 24 hours to obtain 0.78 g of carbon dot material with a diameter of 10 - 15 nm, an emulsification rate of 55%, an average diameter of emulsification bubbles of 70 μm, and demulsification after 1 h.

[0025] Example 9: Steps (1) to (7) are the same as in Example 1 to obtain 2.5 g of orange-yellow carbon dot material; (8)Disperse 1 g of the orange-yellow carbon dot material obtained in step (7) in 10 mL of methanol, add 1 g of potassium methoxide and 1 g of arginine, and stir for 10 minutes until there is no solid precipitation; (9)Heat and stir the system obtained in step (8) at 80 °C for 30 minutes; (10) Centrifuge the system obtained in step (9) at 13,000 rpm for 5 minutes, remove the supernatant, retain the precipitate and vacuum dry it at 60 °C for 24 hours to obtain 0.66 g of carbon dot material with a diameter of 15 - 20 nm, an emulsification rate of 44%, an emulsified bubble diameter of 90 - 105 μm, and demulsification occurs after 1 h.

[0026] In the examples, a mixed solution of acetaldehyde and acetone was added. An attempt was made to use acetone as the sole reagent, but the self - condensation steric hindrance of acetone is large and it is difficult to react, and carbon dots cannot be generated under the same conditions. The carbon dot materials obtained in Examples 7, 8, and 9 have a certain emulsifying effect, but the emulsified bubbles dissipate quickly, indicating that their emulsifying effect is not stable. The reason for demulsification may be the weakening of Brownian motion, the loss of the ability to reduce the interfacial tension, and the inability to maintain the stability of the emulsified bubbles.

Claims

1. A preparation method of aldehyde-ketone synthesized carbon dots with a high emulsification level and excellent wettability, characterized in that: The steps are as follows: (1) Prepare an aqueous NaOH solution with a concentration of 5 - 10 M, stir for 20 - 30 minutes and then let it stand; (2) Slowly add dropwise the aqueous NaOH solution prepared in step (1) into an aqueous acetaldehyde solution and an acetone solution with a mass fraction of 30 - 50%, finish the dropping within 20 - 30 minutes and stir evenly; (3) Under room temperature conditions, stir the system obtained in step (2) for 2 - 5 h to obtain a dark brown paste solution; (4) Add a hydrochloric acid solution to the dark brown paste solution obtained in step (3), adjust the pH of the solution to neutral, and then continuously stir for 4 - 12 h until the system is a yellowish brown solution; (5) Centrifuge the yellowish brown solution obtained in step (4) at a speed of 12000 - 13000 rpm for 3 - 5 minutes, remove the supernatant after centrifugation, and retain the precipitate; (6) Add deionized water to the precipitate obtained in step (5), disperse it evenly by ultrasonic treatment, remove the supernatant after centrifugation, and retain the precipitate; repeat the operations of "adding deionized water to the precipitate - ultrasonic dispersion - centrifugation - retaining the precipitate" 3 - 5 times to obtain a yellowish brown precipitate; (7) Freeze - dry the yellowish brown precipitate obtained in step (6) with liquid nitrogen extraction to obtain a yellow carbon dot material; (8) Disperse 1 - 2 g of the yellow carbon dot material obtained in step (7) in 10 - 20 mL of methanol, add 1 - 2 g of potassium methoxide and 0.5 - 2 g of a nitrogen source, and stir until there is no solid precipitate; (9) Heat - stir the system obtained in step (8) at 70 - 90 °C for 30 - 60 minutes; (10) Centrifuge the system obtained in step (9) at a speed of 10000 - 15000 rpm for 2 - 5 minutes, remove the supernatant, retain the precipitate and dry it to obtain the aldehyde - ketone - synthesized carbon dots with high emulsification level and excellent wettability.

2. The preparation method of aldehyde-ketone synthesized carbon dots with high emulsification level and excellent wettability according to claim 1, characterized in that: In step (2), the volume ratio of the aqueous NaOH solution to the aqueous acetaldehyde solution and the acetone solution is 1:1 - 3:3 - 5.

3. The preparation method of aldehyde-ketone synthesized carbon dots with high emulsification level and excellent wettability as described in claim 1, characterized in that: In step (4), the concentration of the hydrochloric acid solution is 1 - 3 M.

4. The preparation method of aldehyde-ketone synthesized carbon dots with high emulsification level and excellent wettability according to claim 1, characterized in that: In step (7), the conditions for freeze - drying with extraction are a temperature of - 70 ~ - 60 °C and a vacuum degree of < 10 Pa.

5. The preparation method of aldehyde-ketone synthesized carbon dots with high emulsification level and excellent wettability as described in claim 1, characterized in that: The nitrogen source in step (8) is urea, thiourea, lysine, glycine or citrulline.

6. The preparation method of aldehyde-ketone synthesized carbon dots with high emulsification level and excellent wettability as described in claim 1, characterized in that: In step (10), it is vacuum - dried at 60 - 80 °C for 15 - 30 hours.

7. An aldehyde-ketone synthesized carbon dot with a high emulsification level and excellent wettability, characterized in that: It is prepared by the preparation method described in any one of claims 1 - 6.

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