Carbon quantum dot quaternary ammonium salt corrosion inhibitor as well as preparation method and application thereof

Abstract

The invention discloses a carbon quantum dot quaternary ammonium salt corrosion inhibitor and a preparation method and application thereof, and belongs to the technical field of corrosion inhibitor preparation. The preparation method comprises the following steps: dissolving L-glutamic acid in deionized water to prepare a glutamic acid solution; carrying out hydrothermal reaction on the glutamic acid solution by adopting a hydrothermal method to prepare carbon quantum dots; dissolving carbon quantum dots in a solvent to prepare a carbon quantum dot solution; and mixing the carbon quantum dot solution with an iodomethane aqueous solution, reacting under a water bath condition, and sequentially carrying out centrifugal separation, dialysis and drying treatment after the reaction is finished, so as to prepare the carbon quantum dot quaternary ammonium salt corrosion inhibitor. The technical problems that in the prior art, corrosion inhibitors are unstable in corrosion inhibition effect, greatly affected by the external environment, poor in compatibility and unfriendly to the environment are solved.

Description

Technical Field

[0001] This invention belongs to the field of corrosion inhibitor preparation technology, specifically relating to a carbon quantum dot quaternary ammonium salt corrosion inhibitor, its preparation method, and its application. Background Technology

[0002] In the field of metal protection, corrosion inhibitors are an important class of chemical substances used to slow down the corrosion rate of metals in corrosive environments. Corrosion inhibitors achieve their anti-corrosion effect by forming a protective film on the surface of the pipe metal, slowing down or preventing the electrochemical reaction between the metal and the medium. Using corrosion inhibitors does not change the corrosive environment, does not increase equipment investment, and has the advantages of low dosage, ease of use, and significant effect. However, traditional corrosion inhibitors have many drawbacks, such as high toxicity, poor biodegradability, and limited corrosion inhibition efficiency, making it difficult to meet the stringent requirements of modern industry for green, long-lasting, and highly efficient metal protection.

[0003] In recent years, carbon quantum dots, as a novel carbon nanomaterial, have attracted much attention in the research and application of corrosion inhibitors due to their unique nanosize effect, good water solubility, low toxicity and environmental friendliness.

[0004] For example, Chinese invention patent CN108727268A discloses a rosin imidazoline quaternary ammonium salt compound, a corrosion inhibitor, and a preparation method. This technical solution mainly provides a rosin imidazoline quaternary ammonium salt compound, introducing p-heteroatoms with strong adsorption capacity into the quaternary ammonium salt molecule structure, further enhancing the compound's adsorption capacity on metal surfaces. However, in some complex corrosive environments, such as high temperature, high mineralization, and high acidity / alkalinity, the corrosion inhibitor exhibits poor stability. In dynamic or harsh environments, the protective film may break down or peel off. This fails to meet the demand for long-term, efficient protection of metallic materials. Furthermore, existing corrosion inhibitors have poor compatibility with some special metallic materials or other additives, affecting the corrosion inhibition effect and the overall performance of the system. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a carbon quantum dot quaternary ammonium salt corrosion inhibitor, its preparation method, and its application. This addresses the technical problems of existing corrosion inhibitors, such as unstable corrosion inhibition effects, significant susceptibility to external environmental influences, poor compatibility, and environmental unfriendliness. The carbon quantum dot quaternary ammonium salt corrosion inhibitor provided by the present invention exhibits highly efficient corrosion inhibition performance, maintaining stability under various corrosive environments and significantly reducing the corrosion rate of metals, thus extending the service life of metal equipment and components. Furthermore, the corrosion inhibitor provided by the present invention is environmentally friendly, with widely available and low-cost raw materials, and causes minimal environmental pollution during production, use, and disposal, meeting the requirements of sustainable development.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a method for preparing a carbon quantum dot quaternary ammonium salt corrosion inhibitor, comprising the following steps: L-glutamic acid was dissolved in deionized water to prepare a glutamic acid solution; the glutamic acid solution was subjected to a hydrothermal reaction to obtain carbon quantum dots; the carbon quantum dots were dissolved in a solvent to prepare a carbon quantum dot solution; the carbon quantum dot solution and an aqueous solution of iodomethane were mixed and reacted under water bath conditions; after the reaction was completed, the mixture was subjected to centrifugation, dialysis and drying to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor.

[0007] In one embodiment, the concentration of the L-glutamic acid solution is 0.05~0.5 mol / L; the concentration of the iodomethane aqueous solution is 0.1~3 mol / L.

[0008] In one embodiment, the pH value of the glutamic acid solution is 7-9.

[0009] In one embodiment, the hydrothermal reaction temperature is 160~200°C, and the hydrothermal reaction time is 8~16h.

[0010] In one embodiment, the molar ratio of carbon quantum dots in the carbon quantum dot solution to iodomethane in the iodomethane aqueous solution is (1:4) to (1:6).

[0011] In one embodiment, the reaction conditions are as follows: the reaction is carried out at a temperature of 20~60°C in a water bath for 6~12 hours.

[0012] In one embodiment, the solvent is one of methanol, acetonitrile, N,N-dimethylformamide, and xylene.

[0013] In one embodiment, the volume ratio of the carbon quantum dot solution to the aqueous iodomethane solution is 1:1.

[0014] The present invention also provides a carbon quantum dot quaternary ammonium salt corrosion inhibitor prepared by the above-described method for preparing carbon quantum dot quaternary ammonium salt corrosion inhibitor.

[0015] The present invention also provides an application of a carbon quantum dot quaternary ammonium salt corrosion inhibitor prepared by the above-mentioned method for metal corrosion inhibition.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing a carbon quantum dot quaternary ammonium salt corrosion inhibitor. The inhibitor molecule contains quaternary ammonium salt cationic groups, which can be directionally adsorbed onto negatively charged sites on the metal surface under electrostatic adsorption. Simultaneously, carbon quantum dots possess a large specific surface area and abundant functional groups, and exhibit a conjugated structure. They can attract and aggregate through intermolecular forces such as van der Waals forces and hydrogen bonds, forming a continuous and dense protective film with good chemical stability, significantly improving corrosion inhibition efficiency. The carbon quantum dot quaternary ammonium salt corrosion inhibitor prepared by this invention exhibits strong adaptability to the external environment. In acidic environments, the quaternary ammonium salt groups can form stable ion pairs with hydrogen ions, maintaining the stability of adsorption on the metal surface. In solutions containing corrosive ions such as chloride and sulfate ions, they can undergo ion exchange or electrostatic shielding with anions, reducing the contact between corrosive anions and the metal surface. Furthermore, the functional groups on the carbon quantum dot surface can also maintain the performance of the protective film through interaction with the metal surface in alkaline environments, resulting in good corrosion inhibition effects over a wide pH range. The carbon quantum dot quaternary ammonium salt corrosion inhibitor prepared in this invention exhibits excellent corrosion inhibition effects on various metallic materials due to electrostatic and chemisorption effects. Carbon quantum dots themselves possess excellent stability, do not affect the inherent properties of the metal, and allow the corrosion inhibitor to be used in media containing various ions, pH levels, and hardnesses. It exhibits salt and acid / alkali resistance, is less affected by various factors in the medium, and demonstrates good adaptability and stability. Compared with traditional corrosion inhibitors, the corrosion inhibitor of this invention is more easily degraded by microorganisms after use, does not accumulate in the environment, and is environmentally friendly. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the preparation of carbon quantum dots according to the present invention; Figure 2 This is a schematic diagram illustrating the preparation of a carbon quantum dot quaternary ammonium salt corrosion inhibitor according to the present invention; Figure 3 A schematic diagram showing the mass loss test results under different concentrations of carbon quantum dot quaternary ammonium salt corrosion inhibitor NaCl conditions; Figure 4 A schematic diagram showing the mass loss test results under different concentrations of carbon quantum dot quaternary ammonium salt corrosion inhibitor HCl conditions; Figure 5 The infrared spectrum of the carbon quantum dot quaternary ammonium salt corrosion inhibitor prepared in Example 3 of the present invention is shown. Detailed Implementation

[0018] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0019] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0020] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0021] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0022] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0023] To overcome the shortcomings of traditional corrosion inhibitors, such as poor stability, high toxicity, poor biodegradability, and limited corrosion inhibition efficiency, this study utilized the unique physicochemical properties of carbon quantum dots to precisely adjust the proportions and properties of each component. This significantly enhanced the corrosion inhibition performance, stability, and excellent compatibility of the inhibitor, improving its heat resistance, acid and alkali resistance, and salt resistance in practical operations. It also exhibited good tolerance to ultraviolet light and humid environments. This carbon quantum dot corrosion inhibitor shows broad application prospects in oil and gas resource extraction and possesses high economic value and market potential.

[0024] This invention provides a method for preparing a carbon quantum dot quaternary ammonium salt corrosion inhibitor, comprising the following steps: Step 1: Preparation of carbon quantum dots. Glutamic acid and deionized water are added to a beaker. L-glutamic acid is dissolved in the deionized water and sonicated to ensure homogeneity, yielding a glutamic acid solution with a concentration of 0.05–0.5 mol / L. The pH of the glutamic acid solution is adjusted to 7–9 using standard solutions of sodium hydroxide and hydrochloric acid. The glutamic acid solution is then placed in a hydrothermal reactor and reacted at 160–220°C for 8–16 hours. Intramolecular dehydration of the carboxyl and amino groups forms peptide bonds. These peptide bonds further lose hydrogen and oxygen atoms at high temperatures, forming carbon cores with conjugated structures. Some unreacted groups from the glutamic acid molecule remain on the surface of the carbon core, thus preparing carbon quantum dots with carboxyl, amino, and amide functional groups on their surface. The prepared carbon quantum dots are dissolved in a solvent to obtain a pale yellow carbon quantum dot solution. The reaction equation is as follows: Figure 1 As shown.

[0025] Step 2: Preparation of carbon quantum dot quaternary ammonium salt corrosion inhibitor. The obtained carbon quantum dot solution was transferred into a three-necked flask equipped with a reflux condenser, thermometer, and dropping funnel. Iodomethane aqueous solution was added, wherein the molar ratio of carbon quantum dot solution to iodomethane aqueous solution was (1:4) to (1:6). The reaction was carried out at a temperature of 20-60℃ in a water bath for 6-12 hours to graft quaternary ammonium groups onto the surface of carbon quantum dots. The reaction equation is as follows: Figure 2 As shown.

[0026] The third step is product post-processing, which involves centrifuging, dialysis, and drying the product obtained from the reaction to obtain a pure carbon quantum dot quaternary ammonium salt corrosion inhibitor product.

[0027] As a further improvement of the present invention, the solvent mentioned in the first step is one of methanol, acetonitrile, N,N-dimethylformamide and xylene.

[0028] As a further improvement of the present invention, the concentration of the iodomethane aqueous solution in the second step is 0.1~3 mol / L.

[0029] As a further improvement of the present invention, the aqueous solution of iodomethane mentioned in the second step needs to be added dropwise.

[0030] The carbon quantum dot quaternary ammonium salt corrosion inhibitor prepared by this invention has good temperature resistance, salt resistance, acid and alkali resistance and chemical stability. It can remain stable in corrosive environments with a wide pH range, better adhere to the metal surface and adsorb to each other to form a more stable and dense protective film, significantly reduce the corrosion rate of metals and extend the service life of metal equipment and components.

[0031] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0032] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0033] Example 1 L-glutamic acid (1.47 g) and deionized water (200 mL) were dissolved in an ultrasonic bath for 0.5 h. The pH of the solution was adjusted to be between 7 and 9 using sodium hydroxide solution and hydrochloric acid solution. The solution was then transferred to a hydrothermal reactor, heated to 160 °C, and reacted for 8 h. After dialysis and drying, carbon quantum dots were obtained.

[0034] The prepared carbon quantum dots were dissolved in N,N-dimethylformamide solvent (100 mL) to obtain a carbon quantum dot solution.

[0035] A carbon quantum dot solution (100 mL) and a 0.11 mol / L iodomethane aqueous solution (100 mL) were added to a three-necked flask equipped with a reflux condenser, a thermometer, and a dropping funnel. The mixture was reacted in a water bath at 20 °C for 6 h to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor. The final product was obtained by centrifugation, dialysis, washing, and drying.

[0036] Example 2 L-glutamic acid (3.74 g) and deionized water (200 mL) were dissolved thoroughly in an ultrasonic bath for 1 hour. The pH of the solution was adjusted to be between 7 and 9 using sodium hydroxide solution and hydrochloric acid solution. The solution was then transferred to a hydrothermal reactor, heated to 170 °C, and reacted for 9 hours. After dialysis and drying, carbon quantum dots were obtained.

[0037] The prepared carbon quantum dots were dissolved in N,N-dimethylformamide solvent (100 mL) to obtain a carbon quantum dot solution.

[0038] A carbon quantum dot solution (100 mL) and a 0.3 mol / L iodomethane aqueous solution (100 mL) were added to a three-necked flask equipped with a reflux condenser, a thermometer, and a dropping funnel. The mixture was reacted in a water bath at 25 °C for 8 h to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor. The final product was obtained by centrifugation, dialysis, washing, and drying.

[0039] Example 3 5.88 g of L-glutamic acid and 200 mL of deionized water were dissolved in an ultrasonic bath for 0.5 h. The pH of the solution was adjusted to be between 7 and 9 using sodium hydroxide solution and hydrochloric acid solution. The solution was then transferred to a hydrothermal reactor, heated to 180 °C, and reacted for 10 h. After dialysis and drying, carbon quantum dots were obtained.

[0040] The prepared carbon quantum dots were dissolved in N,N-dimethylformamide solvent (100 mL) to obtain a carbon quantum dot solution.

[0041] A carbon quantum dot solution (100 mL) and a 2.1 mol / L iodomethane aqueous solution (100 mL) were added to a three-necked flask equipped with a reflux condenser, a thermometer, and a dropping funnel. The mixture was reacted in a water bath at 30 °C for 10 h to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor. The final product was obtained by centrifugation, dialysis, washing, and drying.

[0042] Example 4 11.76 g of L-glutamic acid and 200 mL of deionized water were dissolved in an ultrasonic bath for 1 hour. The pH of the solution was adjusted to be between 7 and 9 using sodium hydroxide and hydrochloric acid solutions. The solution was then transferred to a hydrothermal reactor, heated to 190 °C, and reacted for 12 hours. After dialysis and drying, carbon quantum dots were obtained.

[0043] The prepared carbon quantum dots were dissolved in N,N-dimethylformamide solvent (100 mL) to obtain a carbon quantum dot solution.

[0044] A carbon quantum dot solution (100 mL) and a 1.5 mol / L iodomethane aqueous solution (100 mL) were added to a three-necked flask equipped with a reflux condenser, a thermometer, and a dropping funnel. The mixture was reacted in a water bath at 30 °C for 12 h to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor. The final product was obtained by centrifugation, dialysis, washing, and drying.

[0045] Example 4 14.7 g of L-glutamic acid and 200 mL of deionized water were dissolved in an ultrasonic bath for 1 hour. The pH of the solution was adjusted to be between 7 and 9 using sodium hydroxide solution and hydrochloric acid solution. The solution was then transferred to a hydrothermal reactor, heated to 160 °C, and reacted for 10 hours. After dialysis and drying, carbon quantum dots were obtained.

[0046] The prepared carbon quantum dots were dissolved in N,N-dimethylformamide solvent (100 mL) to obtain a carbon quantum dot solution.

[0047] A carbon quantum dot solution (100 mL) and a 2.5 mol / L iodomethane aqueous solution (100 mL) were added to a three-necked flask equipped with a reflux condenser, a thermometer, and a dropping funnel. The mixture was reacted in a water bath at 40 °C for 8 h to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor. The final product was obtained by centrifugation, dialysis, washing, and drying.

[0048] Example 5 14.7 g of L-glutamic acid and 200 mL of deionized water were dissolved in an ultrasonic bath for 0.5 h. The pH of the solution was adjusted to be between 7 and 9 using sodium hydroxide solution and hydrochloric acid solution. The solution was then transferred to a hydrothermal reactor, heated to 180 °C, and reacted for 12 h. After dialysis and drying, carbon quantum dots were obtained.

[0049] The prepared carbon quantum dots were dissolved in N,N-dimethylformamide solvent (100 mL) to obtain a carbon quantum dot solution.

[0050] A carbon quantum dot solution (100 mL) and a 2.7 mol / L iodomethane aqueous solution (100 mL) were added to a three-necked flask equipped with a reflux condenser, a thermometer, and a dropping funnel. The mixture was reacted in a water bath at 50 °C for 10 h to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor. The final product was obtained by centrifugation, dialysis, washing, and drying.

[0051] Example 6 14.7 g of L-glutamic acid was dissolved in 200 mL of deionized water in an ultrasonic bath for 1 hour. The pH of the solution was adjusted to be between 7 and 9 using sodium hydroxide and hydrochloric acid solutions. The solution was then transferred to a hydrothermal reactor, heated to 200 °C, and reacted for 16 hours. After dialysis and drying, carbon quantum dots were obtained.

[0052] The prepared carbon quantum dots were dissolved in N,N-dimethylformamide solvent (100 mL) to obtain a carbon quantum dot solution.

[0053] A carbon quantum dot solution (100 mL) and a 3 mol / L iodomethane aqueous solution (100 mL) were added to a three-necked flask equipped with a reflux condenser, a thermometer, and a dropping funnel. The mixture was reacted in a water bath at 60 °C for 12 h to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor. The final product was obtained by centrifugation, dialysis, washing, and drying.

[0054] Application performance testing: Thermal stability test: Prepare corrosion inhibitor samples for tests 1-6. Weigh equal amounts of the corrosion inhibitor samples and place them into different glass sample bottles, then seal them. Place these sample bottles in a constant temperature drying oven at 70°C for 3 days and observe the appearance changes of the corrosion inhibitors. The results show that the corrosion inhibitor samples did not exhibit obvious precipitation, discoloration, or stratification, and the corrosion inhibitor structure did not change significantly, proving that the corrosion inhibitors have thermal stability.

[0055] Chemical stability test: The corrosion inhibitor solutions from Test Examples 1-6 were added to buffer solutions with pH values ​​of 5 and 9, respectively, to maintain a consistent corrosion inhibitor concentration. The solutions were left at room temperature for 24 hours. Every 6 hours, 2 mL of solution was taken, and the absorbance was measured using a UV-Vis spectrophotometer. The corrosion inhibitor did not decompose or react under different chemical environments, demonstrating its excellent acid and alkali resistance.

[0056] Mass loss test: Mass loss tests were conducted on carbon steel under different concentrations of carbon quantum dot quaternary ammonium salt corrosion inhibitors in 3.5% NaCl solution with saturated CO2 and 0.1 mol / L HCl solution for 24 hours. The mass change before and after the test was calculated by comparing with a blank control group. The results are as follows: Figure 3 , Figure 4 As shown.

[0057] Depend on Figure 3 , Figure 4 It can be seen that when the corrosion inhibitor concentration is 0%, the metal is more susceptible to corrosion. The metal corrosion inhibition efficiency increases continuously with the increase of the corrosion inhibitor concentration, and this increase is more pronounced at lower concentrations. After the concentration increases to 40 mg / L, the corrosion inhibition efficiency gradually stabilizes, reaching over 90% in salt water and over 85% in acidic environments. In conclusion, considering both effectiveness and economy, the optimal concentration of this corrosion inhibitor is approximately 45 mg / L.

[0058] Depend on Figure 5 It is known that the carbon quantum dot quaternary ammonium salt corrosion inhibitor obtained in Example 3 has a chemical structure containing carboxyl groups, hydroxyl groups, and infrared characteristics of typical ionic bonds and organic functional groups of quaternary ammonium salts.

[0059] In summary, the carbon quantum dot quaternary ammonium salt corrosion inhibitor disclosed in this invention possesses excellent temperature resistance, salt resistance, acid and alkali resistance, and chemical stability, maintaining stability in corrosive environments across a wide pH range. Simultaneously, it forms a more stable and dense protective film, significantly reducing the corrosion rate of metals and meeting the application requirements for metal corrosion inhibition in chemical production.

[0060] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a carbon quantum dot quaternary ammonium salt corrosion inhibitor, characterized in that, Includes the following steps: L-glutamic acid was dissolved in deionized water to prepare a glutamic acid solution; the glutamic acid solution was subjected to a hydrothermal reaction to obtain carbon quantum dots; the carbon quantum dots were dissolved in a solvent to prepare a carbon quantum dot solution; the carbon quantum dot solution and an aqueous solution of iodomethane were mixed and reacted under water bath conditions; after the reaction was completed, the mixture was subjected to centrifugation, dialysis and drying to obtain a carbon quantum dot quaternary ammonium salt corrosion inhibitor.

2. The method for preparing the carbon quantum dot quaternary ammonium salt corrosion inhibitor according to claim 1, characterized in that, The concentration of the L-glutamic acid solution is 0.05~0.5 mol / L; the concentration of the iodomethane aqueous solution is 0.1~3 mol / L.

3. The method for preparing the carbon quantum dot quaternary ammonium salt corrosion inhibitor according to claim 1, characterized in that, The pH value of the glutamic acid solution is 7-9.

4. The method for preparing the carbon quantum dot quaternary ammonium salt corrosion inhibitor according to claim 1, characterized in that, The hydrothermal reaction temperature is 160~200℃, and the hydrothermal reaction time is 8~16h.

5. The method for preparing the carbon quantum dot quaternary ammonium salt corrosion inhibitor according to claim 1, characterized in that, The molar ratio of carbon quantum dots in the carbon quantum dot solution to iodomethane in the iodomethane aqueous solution is (1:4) to (1:6).

6. The method for preparing the carbon quantum dot quaternary ammonium salt corrosion inhibitor according to claim 1, characterized in that, The reaction conditions are as follows: react for 6 to 12 hours at a water bath temperature of 20 to 60°C.

7. The method for preparing the carbon quantum dot quaternary ammonium salt corrosion inhibitor according to claim 1, characterized in that, The solvent is one of methanol, acetonitrile, N,N-dimethylformamide, and xylene.

8. The method for preparing the carbon quantum dot quaternary ammonium salt corrosion inhibitor according to claim 1, characterized in that, The volume ratio of the carbon quantum dot solution to the iodomethane aqueous solution is 1:

1.

9. A carbon quantum dot quaternary ammonium salt corrosion inhibitor prepared by the method of any one of claims 1 to 8.

10. The application of the carbon quantum dot quaternary ammonium salt corrosion inhibitor prepared by the method of any one of claims 1 to 8 in metal corrosion inhibition.

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