Preparation method and application of carbon quantum dot corrosion inhibitor

Abstract

The application relates to a preparation method and application of a carbon quantum dot corrosion inhibitor, and comprises the following steps: uniformly mixing chitosan, amino acid and water to obtain a mixed solution; after the mixed solution is irradiated by laser for 1-12 hours, solid-liquid separation, washing and drying are carried out to obtain a carbon quantum dot corrosion inhibitor; wherein the pulse width of the laser is 18-30 ns, the frequency is 50-200 Hz, the wavelength is 1500-1800 nm, and the single pulse energy is 100-250 mJ. The raw materials such as chitosan and amino acid adopted by the application are widely sourced, are pollution-free, have strong environmental protection, and the prepared carbon quantum dot corrosion inhibitor target product has good corrosion inhibition performance on carbon steel, and the corrosion inhibition efficiency is as high as 97.4%.

Description

Technical Field

[0001] This invention relates to a method for preparing a carbon quantum dot corrosion inhibitor and its application, belonging to the field of corrosion inhibitor synthesis and preparation. Background Technology

[0002] Carbon steel is widely used in both industrial and agricultural fields. However, its inherent strong corrosiveness greatly limits its application in acidic media. For example, acidification processes in the petroleum industry use 15% hydrochloric acid solutions, and the equipment storing this acid is made of Q235 or N80 carbon steel. This equipment is highly susceptible to corrosion under high-concentration acid conditions. Adding corrosion inhibitors to acidic media is one of the most effective methods to slow down or prevent carbon steel corrosion. Currently, commonly used industrial corrosion inhibitors are mainly organic compounds containing N, S, and O atoms, with multiple bonds in their structure or large molecular weights. Their accepted corrosion inhibition mechanism is adsorption to the metal surface. Although organic corrosion inhibitors have satisfactory corrosion inhibition effects, they are highly toxic and irritating to the skin, posing a threat to human health and the environment. With the goals of high performance, low cost, and renewability, research and development of environmentally friendly bio-based corrosion inhibitors based on green chemistry principles are gradually becoming a key direction for corrosion inhibitor development in the new century.

[0003] Chinese invention patent specification CN202210377795.2 discloses an asphalt-based carbon quantum dot corrosion inhibitor, its preparation method, and its application. The preparation method uses coal tar pitch as a precursor and cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, or polyvinylpyrrolidone surfactant as a passivating agent and dispersant, to prepare the carbon quantum dot corrosion inhibitor via a one-step hydrothermal method. This preparation method requires hydrothermal conditions, necessitates heating, and consumes additives such as passivating agents and dispersants; its environmental friendliness and economic efficiency have room for further improvement.

[0004] Chinese invention patent specification CN202011321472.9 discloses a composite quantum dot carbon steel corrosion inhibitor, its preparation method, and its application. The composite quantum dot carbon steel corrosion inhibitor is prepared using hexamethylenetetramine and itaconic acid as raw materials via a hydrothermal method, with the reaction occurring at 150°C. This preparation method also requires hydrothermal conditions and uses raw materials such as hexamethylenetetramine, which are irritating to the skin, easily sublimate upon heating, and are flammable. Therefore, its environmental friendliness and safety have room for further improvement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, one of the objectives of this invention is to provide a method for preparing an environmentally friendly carbon quantum dot corrosion inhibitor; another objective of this invention is to provide the application of the carbon quantum dot corrosion inhibitor in reducing the corrosion rate of carbon steel in acidic solution environments.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] A method for preparing a carbon quantum dot corrosion inhibitor includes the following steps:

[0008] S1. Mix chitosan, amino acids and water evenly to obtain a mixed solution;

[0009] S2. After irradiating the mixed solution with a laser for 1-12 hours, the solid and liquid are separated, washed, and dried to obtain a carbon quantum dot sustained-release agent.

[0010] The laser pulse width is 18-30 ns, the frequency is 50-200 Hz, the wavelength is 1500-1800 nm, and the single pulse energy is 100-300 mJ. Further, in step S2, the mixed solution is first irradiated with a first laser for 1-5 hours, then irradiated with a second laser for 1-5 hours, followed by solid-liquid separation, washing, and drying to obtain a carbon quantum dot sustained-release agent.

[0011] The first laser has a pulse width of 18-30 ns, a frequency of 50-100 Hz, a wavelength of 1500-1800 nm, and a single pulse energy of 100-230 mJ, preferably 200-230 mJ; the second laser has a pulse width of 18-30 ns, a frequency of 150-200 Hz, a wavelength of 1500-1800 nm, and a single pulse energy of 100-300 mJ, preferably 200-300 mJ. The applicant's research has found that using two-stage laser irradiation can prevent product agglomeration and obtain carbon quantum dot sustained-release agents with better dispersibility.

[0012] Furthermore, in S2, the mixed solution is first irradiated with a first laser for 1.5-4.5 hours, preferably 1.75-2.25 hours; then the mixed solution is irradiated with a second laser for 1.5-4.5 hours, preferably 1.75-2.5 hours.

[0013] Furthermore, in S2, the single-pulse energy of the first laser is lower than that of the second laser.

[0014] Further, in S1, the average relative molecular weight of the chitosan is 10,000-20,000, preferably 12,000-18,000, and more preferably 14,000-16,000.

[0015] Furthermore, in S1, the amount of amino acids added is 1-3 times the mass of chitosan, preferably 1-2 times; more preferably, the amount of water added is 30-50 times the mass of chitosan, more preferably 35-45 times.

[0016] Further, in step S1, chitosan is first mixed with water, then a co-solvent is added, and the mixture is stirred evenly at 80-100°C to obtain a chitosan solution; then the chitosan solution is stirred evenly with amino acids to obtain a mixed solution; preferably, the co-solvent is one or more of potassium hydroxide, sodium hydroxide, and tetramethylammonium hydroxide; preferably, the amount of co-solvent added is 0.5-2 times the mass of chitosan, more preferably 0.5-1 times.

[0017] Further, in S1, the amino acid includes one or more of L-amino acids, tryptophan, lysine, glycyl-D-leucine, glycyl-DL-leucine, and glutamic acid.

[0018] The application of carbon quantum dot corrosion inhibitors prepared by the above-described method in reducing the corrosion rate of carbon steel in acidic solution environments.

[0019] Furthermore, the concentration of the carbon quantum dot sustained-release agent in the acidic solution is 20-60 mg / L, preferably 30-50 mg / L.

[0020] The preparation principle of the carbon quantum dot corrosion inhibitor of the present invention is explained as follows: After mixing chitosan, amino acids and water to obtain a mixed solution, the mixed solution is irradiated with a high-energy laser pulse, which causes a local high temperature and high pressure state in the mixed solution, thereby transforming the chitosan in the solution into carbon quantum dots. At the same time, through the reaction of functional groups in chitosan and amino acids (such as -NH2 in chitosan and -COOH in amino acids), nitrogen-doped carbon quantum dots are obtained for slow release.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The raw materials used in this invention, such as chitosan and amino acids, are widely available, pollution-free, and environmentally friendly.

[0023] (2) During the preparation of carbon quantum dots, amino acids are introduced into the carbon quantum dots to achieve the doping of nitrogen (N) elements into the carbon quantum dots, thereby improving the corrosion inhibition performance of the target product carbon quantum dot corrosion inhibitor.

[0024] (3) This invention is the first to use a laser pulse method to prepare carbon quantum dot corrosion inhibitors. By controlling relevant parameters, carbon quantum dot corrosion inhibitors with excellent corrosion inhibition effects can be obtained. In addition, the size of the carbon quantum dot corrosion inhibitors can be controlled by adjusting the reaction time, so as to meet the preparation requirements of carbon quantum dot corrosion inhibitors with different sizes and properties.

[0025] (4) Compared with conventional methods (hydrothermal method), the preparation method of the present invention does not require additional high-temperature reaction conditions, and has the advantages of being environmentally friendly, time-saving and simple.

[0026] (5) The carbon quantum dot corrosion inhibitor prepared by this invention has good corrosion inhibition performance on carbon steel, with a corrosion inhibition efficiency of up to 97.4%. Attached Figure Description

[0027] Figure 1 These are the Fourier transform infrared (FT-IR) spectra of the obtained CA-CDs-1, CA-CDs-2, and CA-CDs-3 samples.

[0028] Figure 2 UV-Vis spectra of CA-CDs-1, CA-CDs-2 and CA-CDs-3 samples.

[0029] Figure 3 For TEM images, where Figure 3 (a) is a TEM image of CA-CDs-1. Figure 3 (c) is a TEM image of CA-CDs-2. Figure 3 (e) is a TEM image of CA-CDs-3.

[0030] Figure 4 The potentiodynamic polarization curves of carbon steel after 24 hours in 0.5M HCl solution (blank sample) and in mixed solutions of 40 mg / L CA-CDs-1, 40 mg / L CA-CDs-2, and 40 mg / L CA-CDs-3.

[0031] Figure 5 For Nyquist plots, where Figure 5 (a) is the Nyquist plot of carbon steel in 0.5M HCl solution (blank sample). Figure 5 (b) Nyquist plots of carbon steel in a 0.5 M HCl mixture of 40 mg / L CA-CDs-1 and 40 mg / L CA-CDs-3. Figure 5 (c) is the Nyquist plot of carbon steel in a mixture of 40 mg / L CA-CDs-2 and 0.5 M HCl.

[0032] Figure 6 The phase angle diagrams are shown for carbon steel after 24 hours in 0.5M HCl solution (blank sample) and in mixed solutions of 40 mg / L CA-CDs-1, 40 mg / L CA-CDs-2, and 40 mg / L CA-CDs-3.

[0033] Figure 7The potentiodynamic polarization curves of carbon steel after 24 hours in a mixed solution of chitosan and HCl or a mixed solution of L-amino acid and HCl.

[0034] Figure 8 This is a TEM image of CA-CDs-S. Detailed Implementation

[0035] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0036] Example 1

[0037] Weigh 5 grams of chitosan with an average molecular weight of 15,000 and add it to a beaker containing 200 ml of deionized water. Then add 5 grams of potassium hydroxide as a solvent, control the solution temperature at 80°C, and turn on magnetic stirring until the chitosan is completely dissolved. Subsequently, add 5 grams of L-amino acid and continue stirring until the L-amino acid is completely dissolved to obtain a mixed solution.

[0038] The above-mentioned mixed solution was transferred to a 500 mL high-temperature and high-pressure resistant reaction vessel and then to a laser reactor. A staged reaction mode was employed: first, the reaction was carried out for 2 hours at a pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 220 mJ; then, the reaction was carried out for 1 hour at the same pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 250 mJ. After the reaction, the solution was cooled to room temperature and centrifuged; it was then washed three times each with deionized water and anhydrous ethanol; finally, it was freeze-dried to obtain the target product, an N-doped carbon quantum dot corrosion inhibitor, labeled CA-CDs-1, with a yield of approximately 67.2%.

[0039] Example 2

[0040] Weigh 5 grams of chitosan with an average molecular weight of 15,000 and add it to a beaker containing 200 ml of deionized water. Then add 5 grams of potassium hydroxide as a solvent, control the solution temperature at 80°C, and turn on magnetic stirring until the chitosan is completely dissolved. Subsequently, add 5 grams of glutamic acid and continue stirring until the glutamic acid is completely dissolved to obtain a mixed solution.

[0041] The above-mentioned mixed solution was transferred to a 500 mL high-temperature and high-pressure resistant reaction vessel, and then transferred to a laser reactor for a staged reaction: first, the reaction was carried out for 2 hours at a pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 220 mJ; then, the reaction was carried out for 2 hours at a pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 250 mJ. After the reaction, the mixture was cooled to room temperature and centrifuged and filtered; then washed three times each with deionized water and anhydrous ethanol; finally, it was freeze-dried to obtain the target product, an N-doped carbon quantum dot corrosion inhibitor, labeled CA-CDs-2, with a yield of approximately 67.5%.

[0042] Example 3

[0043] Weigh 5 grams of chitosan with an average molecular weight of 15,000 and add it to a beaker containing 200 ml of deionized water. Then add 5 grams of potassium hydroxide as a solvent, control the solution temperature at 80°C, and turn on magnetic stirring until the chitosan is completely dissolved. Subsequently, add 5 grams of glutamic acid and continue stirring until the tryptophan is completely dissolved to obtain a mixed solution.

[0044] The above-mentioned mixed solution was transferred to a 500 mL high-temperature and high-pressure resistant reaction vessel, and then transferred to a laser reactor for a staged reaction: first, the reaction was carried out for 2 hours at a pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 220 mJ; then, the reaction was carried out for 3 hours at a pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 250 mJ. After the reaction, the mixture was cooled to room temperature and centrifuged and filtered; then washed three times each with deionized water and anhydrous ethanol; finally, it was freeze-dried to obtain the target product, an N-doped carbon quantum dot corrosion inhibitor, labeled CA-CDs-3, with a yield of approximately 67.9%.

[0045] Ten milligrams of CA-CDs-1, CA-CDs-2, and CA-CDs-3 were taken respectively, and their morphology and phase structure were characterized using infrared spectroscopy, ultraviolet-visible spectroscopy, and transmission electron microscopy (TEM). The structural and morphological results obtained are as follows: Figure 1 , Figure 2 , Figure 3 As shown.

[0046] Figure 1 The Fourier transform infrared (FT-IR) spectra of samples CA-CDs-1, CA-CDs-2, and CA-CDs-3 are shown in the figure. The image shows the 3489 cm⁻¹... -1 and 3450cm -1The absorption peaks at 1787 cm⁻¹ are the stretching vibration peaks of NH and OH, respectively; -1 The absorption peaks are the stretching vibration peaks of C=O; 1659 and 1432 cm⁻¹ -1 The absorption peak is the vibrational peak of CT; 1315 cmT< / s -1 The absorption peak is the CN stretching vibration peak.

[0047] Figure 2 The images show the UV-Vis spectra of chitosan, L-amino acids, CA-CDs-1, CA-CDs-2, and CA-CDs-3 samples. The absorption peak at 203 nm is sp. 2 The π-π* electron transition of hybrid C, the absorption peak at 295 nm is the n-π* electron transition in the C=N bond; compared with chitosan and L amino acids, the absorption peaks at 203 nm and 295 nm have both shifted slightly.

[0048] As can be seen, the present invention has successfully prepared an N-doped carbon quantum dot corrosion inhibitor. Figure 3 Transmission electron microscopy (TEM) images of CA-CDs-1, CA-CDs-2, and CA-CDs-3 samples are shown. It can be observed that CA-CDs-1 and CA-CDs-2 are uniformly dispersed without aggregation, while CA-CDs-3 exhibits aggregation. The particle sizes of CA-CDs-1 and CA-CDs-2 are between 4-10 nm and 8-20 nm, respectively, while the particle size of CA-CDs-3 reaches 10-80 nm.

[0049] Cut three pieces of carbon steel with a size of 1 cm × 1 cm, and polish the surface of the carbon steel with sandpaper of 300 grit, 500 grit, 800 grit and 1200 grit in turn. After polishing, clean the carbon steel with deionized water, anhydrous ethanol and acetone in turn under ultrasonic treatment, and then dry it under vacuum.

[0050] The three treated carbon steel pieces were immersed in a 0.5M HCl mixed solution of 40 mg / L CA-CDs-1, 40 mg / L CA-CDs-2, and 40 mg / L CA-CDs-3 for 24 hours, respectively, while maintaining the solution temperature at 25°C. After immersion, the corresponding carbon steel pieces were removed and set aside for later use. Measurements were performed using a classic three-electrode system, with the carbon steel electrode as the working electrode, the Pt electrode as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves of the carbon steel in solutions of different concentrations of corrosion inhibitors were measured. The results are as follows: Figure 4 , Figure 5 as well as Figure 6 As shown.

[0051] Figure 4 and Figure 7 The potentiodynamic polarization curves of carbon steel after 24 hours in 0.5M HCl solution (blank sample, without corrosion inhibitor) and in mixed solutions of 40 mg / L CA-CDs-1, 40 mg / L CA-CDs-2, 40 mg / L CA-CDs-3, 40 mg / L chitosan, and 40 mg / L L-amino acid after 24 hours are shown. It can be observed that compared with the blank control sample, the corrosion potential of CA-CDs-1, CA-CDs-2, and CA-CDs-3 shifts negatively, and the reduction in corrosion current is more significant for CA-CDs-1, CA-CDs-2, and CA-CDs-3. The corrosion current densities of CA-CDs-1, CA-CDs-2, and CA-CDs-3 are 26.1 μA cm⁻¹. -2 8.6μA cm -2 and 36.9 μA cm -2 The corrosion current density of the blank control sample, chitosan, and L-amino acid was 318.5 μA cm⁻¹. -2 211.80μA cm -2 190.3 μA cm -2 The corrosion inhibition efficiency (η) is calculated using the corrosion current density and the following formula. i ):

[0052]

[0053] Among them, i corr(0) and i corr(inh) The current densities are those of the blank sample and the sample with added corrosion inhibitors, respectively. Calculations showed that the corrosion inhibition efficiencies of CA-CDs-1, CA-CDs-2, CA-CDs-3, chitosan, and L-amino acids were 91.8%, 97.3%, 88.4%, 33.5%, and 40.1%, respectively.

[0054] Figure 5The Nyquist plots are shown for carbon steel after 24 hours in 0.5M HCl solution (blank sample) and in mixed solutions of 40 mg / L CA-CDs-1, 40 mg / L CA-CDs-2, and 40 mg / L CA-CDs-3. It can be observed that the Nyquist plot is a semi-circular arc compressed along the Y-axis, and the radius of the arc along the X-axis reflects the corrosion inhibition efficiency of the sample. Generally, a larger radius indicates a larger transferred charge (Rct) at the solution-carbon steel interface, resulting in higher corrosion inhibition efficiency; conversely, a smaller radius indicates lower corrosion inhibition efficiency. Compared to the blank sample, the X-axis arc radii of CA-CDs-1, CA-CDs-2, and CA-CDs-3 are much larger, and their Rct values ​​are 440.9 Ωcm. 2 1492.3Ωcm 2 340.4Ωcm 2 The Rct value is much higher than that of the blank sample (38.8 Ωcm). 2 Using Rct, the corrosion inhibition efficiency (η) is calculated using the following formula. R %):

[0055]

[0056] Among them, R (inh) and R (0) The values ​​are Rct values ​​for adding and not adding corrosion inhibitors, respectively. Calculations show that the corrosion inhibition efficiencies of CA-CDs-1, CA-CDs-2, and CA-CDs-3 are 91.2%, 97.4%, and 88.6%, respectively. A possible reason for this is the poor dispersibility of CA-CDs-3.

[0057] Figure 6 The graph shows the phase angles of carbon steel after 24 hours in 0.5M HCl solution (blank sample) and in mixed solutions of 40 mg / L CA-CDs-1, 40 mg / L CA-CDs-2, and 40 mg / L CA-CDs-3. Generally, the larger the absolute value of the phase angle, the higher the corrosion inhibition efficiency of the sample; conversely, the larger the absolute value of the phase angle, the lower the corrosion inhibition efficiency. The graph shows that compared to the blank sample, the phase angle values ​​of CA-CDs-1, CA-CDs-2, and CA-CDs-3 are much larger, indicating that CA-CDs-1, CA-CDs-2, and CA-CDs-3 have good corrosion inhibition performance.

[0058] Example 4

[0059] Weigh 5 grams of chitosan with an average molecular weight of 15,000 and add it to a beaker containing 200 ml of deionized water. Then add 5 grams of potassium hydroxide as a solvent, control the solution temperature at 80°C, and turn on magnetic stirring until the chitosan is completely dissolved. Subsequently, add 5 grams of tryptophan and continue stirring until the tryptophan is completely dissolved to obtain a mixed solution.

[0060] The above-mentioned mixed solution was transferred to a 500 mL high-temperature and high-pressure resistant reaction vessel and then to a laser reactor. A staged reaction mode was employed: first, the reaction was carried out for 2 hours at a pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 220 mJ; then, the reaction was carried out for another 2 hours at the same pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 250 mJ. After the reaction, the solution was cooled to room temperature and centrifuged and filtered. It was then washed three times each with deionized water and anhydrous ethanol. Finally, it was freeze-dried to obtain the target product, an N-doped carbon quantum dot corrosion inhibitor labeled CA-CDs-7, with a yield of approximately 67.1%. After testing the potentiodynamic polarization curve, the corrosion inhibition efficiency of CA-CDs-7 was calculated to be 97.2% using the aforementioned method.

[0061] Example 5

[0062] Example 4 was repeated, except that the single pulse energy was 225 mJ during the first laser reaction.

[0063] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 65.1%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 96.8% using the aforementioned method.

[0064] Example 6

[0065] Example 4 was repeated, except that the single pulse energy was 230 mJ during the first laser reaction.

[0066] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 65.2%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 96.6% using the aforementioned method.

[0067] Example 7

[0068] Example 4 was repeated, except that the single pulse energy was 210 mJ during the first laser reaction.

[0069] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 66.7%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 96.4% using the aforementioned method.

[0070] Example 8

[0071] Example 4 was repeated, except that the single pulse energy was 200 mJ during the first laser reaction.

[0072] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 65.1%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 94.8% using the aforementioned method.

[0073] Comparative Example 1

[0074] Example 4 was repeated, except that the single pulse energy was 195 mJ during the first laser reaction.

[0075] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 64.9%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 91.7% using the aforementioned method.

[0076] Comparative Example 2

[0077] Example 4 was repeated, except that the single pulse energy was 190 mJ during the first laser reaction.

[0078] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 62.1%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 86.5% using the aforementioned method.

[0079] Example 9

[0080] Example 4 was repeated, except that the single pulse energy was 300 mJ during the second laser reaction.

[0081] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 66.3%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 96.5% using the aforementioned method.

[0082] Comparative Example 3

[0083] Example 4 was repeated, except that the single pulse energy was 190 mJ during the second laser reaction.

[0084] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 64.2%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 89.1% using the aforementioned method.

[0085] Comparative Example 4

[0086] Example 4 was repeated, except that the single pulse energy was 195 mJ during the second laser reaction.

[0087] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 64.4%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 91.2% using the aforementioned method.

[0088] Example 10

[0089] Example 4 was repeated, except that the single pulse energy was 200 mJ during the second laser reaction.

[0090] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 65.8%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 93.0% using the aforementioned method.

[0091] Example 11

[0092] Example 4 was repeated, except that the single pulse energy was 230 mJ during the second laser reaction.

[0093] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 66.2%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 94.4% using the aforementioned method.

[0094] Example 12

[0095] Example 4 was repeated, except that the single pulse energy was 245 mJ during the second laser reaction.

[0096] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 66.3%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 96.3% using the aforementioned method.

[0097] Example 13

[0098] Example 4 was repeated, except that the single pulse energy was 255 mJ during the second laser reaction.

[0099] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 66.5%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 97.4% using the aforementioned method.

[0100] Example 14

[0101] Example 4 was repeated, except that the single pulse energy was 260 mJ during the second laser reaction.

[0102] The final yield of the target product, N-doped carbon quantum dot corrosion inhibitor, was approximately 66.8%. After testing with potentiodynamic polarization curves, its corrosion inhibition efficiency was calculated to be 97.5% using the aforementioned method.

[0103] Example 15

[0104] Weigh 5 grams of chitosan with an average molecular weight of 15,000 and add it to a beaker containing 200 ml of deionized water. Then add 5 grams of potassium hydroxide as a solvent, control the solution temperature at 80°C, and turn on magnetic stirring until the chitosan is completely dissolved. Subsequently, add 5 grams of tryptophan and continue stirring until the tryptophan is completely dissolved to obtain a mixed solution.

[0105] The above-mentioned mixed solution was transferred to a 500 mL high-temperature and high-pressure resistant reaction vessel, and then transferred to a laser reactor for a one-stage reaction: first, the reaction was carried out for 5 hours at a pulse width of 30 ns, a frequency of 100 Hz, a wavelength of 1800 nm, and a single pulse energy of 220 mJ. After the reaction, it was cooled to room temperature and centrifuged and filtered; then washed three times each with deionized water and anhydrous ethanol; finally, it was freeze-dried to obtain the target product, an N-doped carbon quantum dot corrosion inhibitor, labeled CA-CDs-12, with a yield of approximately 62.6%. After testing the potentiodynamic polarization curve, the corrosion inhibition efficiency of CA-CDs-12 was calculated to be 68.5% using the aforementioned method. Figure 8 It can be seen that the aggregation of CA-CDs-12 is quite serious at this time.

[0106] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

Claims

1. A method for preparing a carbon quantum dot corrosion inhibitor, characterized in that, Includes the following steps: S1. Mix chitosan, amino acids and water evenly to obtain a mixed solution; S2. First, irradiate the mixed solution with the first laser for 1-5 hours, then irradiate the mixed solution with the second laser for 1-5 hours. After solid-liquid separation, washing, and drying, carbon quantum dot sustained-release agent is obtained. The first laser has a pulse width of 18-30 ns, a frequency of 50-100 Hz, a wavelength of 1500-1800 nm, and a single pulse energy of 200-230 mJ; the second laser has a pulse width of 18-30 ns, a frequency of 150-200 Hz, a wavelength of 1500-1800 nm, and a single pulse energy of 200-300 mJ.

2. The preparation method according to claim 1, characterized in that, In S2, the mixed solution is first irradiated with the first laser for 1.5-4.5 hours; then the mixed solution is irradiated with the second laser for 1.5-4.5 hours.

3. The preparation method according to claim 1, characterized in that, In S2, the single-pulse energy of the first laser is lower than that of the second laser.

4. The preparation method according to any one of claims 1-3, characterized in that, In S1, the average relative molecular weight of the chitosan is 10,000-20,000.

5. The preparation method according to claim 4, characterized in that, In S1, the average relative molecular weight of the chitosan is 12000-18000.

6. The preparation method according to claim 5, characterized in that, In S1, the average relative molecular weight of the chitosan is 14,000-16,000.

7. The preparation method according to any one of claims 1-3, characterized in that, In S1, the amount of amino acids added is 1-3 times the mass of chitosan.

8. The preparation method according to claim 7, characterized in that, In S1, the amount of amino acids added is 1-2 times the mass of chitosan.

9. The preparation method according to claim 7, characterized in that, In S1, the amount of water added is 30-50 times the mass of chitosan.

10. The preparation method according to claim 9, characterized in that, In S1, the amount of water added is 35-45 times the mass of chitosan.

11. The preparation method according to any one of claims 1-3, characterized in that, In step S1, chitosan is first mixed with water, then a co-solvent is added, and the mixture is stirred evenly at 80-100℃ to obtain a chitosan solution; then the chitosan solution is mixed evenly with amino acids to obtain a mixed solution.

12. The preparation method according to claim 11, characterized in that, The co-solvent is one or more of potassium hydroxide, sodium hydroxide, and tetramethylammonium hydroxide.

13. The preparation method according to claim 11, characterized in that, The amount of the co-solvent added is 0.5-2 times the mass of chitosan.

14. The preparation method according to claim 13, characterized in that, The amount of the co-solvent added is 0.5-1 times the mass of chitosan.

15. The preparation method according to any one of claims 1-3, characterized in that, In S1, the amino acid includes one or more of L-amino acids, tryptophan, lysine, glycyl-D-leucine, glycyl-DL-leucine, and glutamic acid.

16. The application of the carbon quantum dot corrosion inhibitor prepared by the preparation method according to any one of claims 1-15 in reducing the corrosion rate of carbon steel in acidic solution environment.

17. The application according to claim 16, characterized in that, The concentration of carbon quantum dot sustained-release agent in the acidic solution is 20-60 mg / L.

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