Nitrogen-phosphorus-fluorine ternary doped carbon quantum dot corrosion inhibitor as well as preparation method and application thereof

Abstract

The invention relates to the technical field of corrosion inhibitors, in particular to a nitrogen-phosphorus-fluorine ternary doped carbon quantum dot corrosion inhibitor and a preparation method and application thereof. According to the specific technical scheme, the preparation method of the nitrogen-phosphorus-fluorine ternary doped carbon quantum dot corrosion inhibitor comprises the steps that a mixed reaction system of tryptophan and / or a tryptophan derivative, tetrafluorop-benzoquinone, phosphoric acid and a solvent is subjected to a hydrothermal reaction for 4-8 h at the temperature of 160-240 DEG C, and the nitrogen-phosphorus-fluorine ternary doped carbon quantum dot corrosion inhibitor is obtained. The tryptophan and / or the tryptophan derivative, the tetrafluoro p-benzoquinone and the phosphoric acid are subjected to a hydrothermal reaction, and the prepared corrosion inhibitor is good in water solubility and excellent in corrosion resistance, can be applied to the industries such as metal, chemical engineering, petroleum, electric power, papermaking, oil refining, ships, storage and traffic, and has wide application prospects. The corrosion inhibitor is particularly expected to be applied to large equipment such as chemical equipment, metal equipment, petroleum and offshore platforms, and the service life of a matrix can be prolonged when the corrosion inhibitor is applied to the surface of the metal matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion inhibitors, and in particular to a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor, and a preparation method and application thereof. Background Art

[0002] Metals are widely used in various engineering and everyday applications due to their excellent electrical and thermal conductivity, elongation, gloss, hardness, and strength. However, corrosion is a persistent challenge for the safe and stable operation of metal equipment. Corrosion is not only a waste of resources but also results in significant economic losses and even threatens human life. From a thermodynamic perspective, metal corrosion is an inevitable process. Currently, efforts are underway to minimize corrosion and extend the lifespan of metals.

[0003] Currently, there are many methods for metal corrosion protection, such as electrochemical protection (sacrificial anode protection, impressed current cathode protection), isolation (chemical conversion film, non-metallic coating lining), and metal passivation (metals with oxidation ability are exposed to a corrosive environment and form a uniform and dense oxide or hydroxide film on the surface). These methods have disadvantages such as low corrosion inhibition efficiency, waste of resources, and environmental unfriendliness.

[0004] The addition of highly efficient corrosion inhibitors is currently the most cost-effective method in the field of corrosion protection. Due to their low dosage, significant effectiveness, and economical and convenient nature, they have become a key research and development focus in recent years. Compared to inorganic corrosion inhibitors, organic corrosion inhibitors enhance their corrosion inhibition by adsorbing onto metal surfaces through chemical or physical interactions. Therefore, the development of highly efficient, environmentally friendly, and affordable green organic corrosion inhibitors has become a key area of ​​future development. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor and its preparation method and application.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The invention discloses a preparation method of a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor. The method comprises the following steps: subjecting a mixed reaction system of tryptophan and / or a tryptophan derivative, tetrafluoro-p-benzoquinone, phosphoric acid and a solvent to a hydrothermal reaction at 160-240° C. for 4-8 hours to obtain the nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor.

[0008] Preferably, the tryptophan derivative includes 5-hydroxytryptophan and / or 1-methyl-tryptophan, and the solvent includes water and / or acid.

[0009] Preferably, the mass ratio of the phosphoric acid to tryptophan and / or tryptophan derivatives is 1:100-20:100; the mass ratio of the tetrafluoro-p-benzoquinone to tryptophan and / or tryptophan derivatives is 1:100-20:100.

[0010] Preferably, after the hydrothermal reaction is completed, the obtained solution is stirred, ultrasonicated, filtered, centrifuged, dialyzed, and dried, the stirring time is 10-30 min, the ultrasonic treatment time is 10-30 min, the centrifugal speed is 8000-18000 r / min, the molecular weight of the dialysis bag used in the dialysis treatment is 1-6KD, the drying temperature is 60-90 ° C, and the time is 30-60 h.

[0011] Correspondingly, a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor is prepared by the preparation method.

[0012] Preferably, the constituent elements of the corrosion inhibitor include C, H, O, N, P and F, and the size of the corrosion inhibitor is 1-20 nm.

[0013] Preferably, the solubility of the corrosion inhibitor in water is 10-250 mg / mL.

[0014] Correspondingly, a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor prepared by the preparation method is used in corrosion protection of metal substrate surfaces.

[0015] Preferably, the metal substrate includes any one of steel, copper, iron and alloys thereof.

[0016] Preferably, the surface of the metal substrate is immersed in a solution containing nitrogen, phosphorus and fluorine ternary doped carbon quantum dots corrosion inhibitor, thereby achieving protection of the metal substrate.

[0017] The present invention has the following beneficial effects:

[0018] (1) The method for preparing a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor with high corrosion inhibition efficiency provided by the present invention through hydrothermal synthesis has the advantages of convenient operation, low cost and environmental protection;

[0019] (2) The nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor provided by the present invention has excellent water solubility and corrosion resistance. The N, F and P active sites in the corrosion inhibitor are adsorbed and combined with the metal surface, which increases the coverage of the metal surface and thus reduces the corrosion rate of the metal; at the same time, the good water solubility effectively improves the dispersibility of the corrosion inhibitor in an aqueous environment.

[0020] (3) The present invention prepares a corrosion inhibitor by hydrothermal reaction of tryptophan and / or tryptophan derivatives, tetrafluorobenzoquinone, and phosphoric acid. The corrosion inhibitor has good water solubility and excellent corrosion resistance and can be used in industries such as metal, chemical, petroleum, electric power, papermaking, oil refining, shipbuilding, storage, and transportation. It is particularly expected to be used in large-scale equipment such as chemical equipment, metal equipment, petroleum, and offshore platforms. The corrosion inhibitor of the present invention can be used on the surface of a metal substrate to increase the service life of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a TEM image of the corrosion inhibitor prepared in Example 1. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0024] refer to Figure 1 As shown, the present invention discloses a method for preparing a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor, the process is: after tryptophan and / or tryptophan derivatives, tetrafluorobenzoquinone, phosphoric acid and solvent are mixed, then transferred to a high-temperature reactor, hydrothermal reaction occurs at 160-240 ° C for 4-8 hours, after the hydrothermal reaction is completed, the obtained solution is stirred, ultrasonicated, filtered, centrifuged, dialyzed, and dried, wherein the stirring time is 10-30 minutes, the ultrasonic treatment time is 10-30 minutes, the filtration treatment adopts a qualitative filter paper for vacuum filtration; the number of filtration treatments is 3-5 times. The speed of the centrifugal treatment is 8000-18000r / min, the molecular weight of the dialysis bag used in the dialysis treatment is 1-6KD, the temperature of the drying treatment is 60-90 ° C, and the time is 30-60 hours; thus, the nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor is obtained.

[0025] The tryptophan derivatives include but are not limited to 5-hydroxytryptophan and / or 1-methyltryptophan, and the solvent includes but is not limited to water and / or an acid. The mass ratio of the phosphoric acid to the tryptophan and / or the tryptophan derivative is 1:100-20:100; and the mass ratio of the tetrafluoro-p-benzoquinone to the tryptophan and / or the tryptophan derivative is 1:100-20:100.

[0026] The nitrogen, phosphorus, and fluorine ternary doped carbon quantum dot corrosion inhibitor prepared by the present invention comprises elements including C, H, O, N, P, and F. The size of the corrosion inhibitor is 1-20 nm, and the nitrogen, phosphorus, and fluorine ternary doped carbon quantum dot corrosion inhibitor has excellent dispersibility in an aqueous environment. The solubility of the corrosion inhibitor in water is 10-250 mg / mL, and therefore, the nitrogen, phosphorus, and fluorine ternary doped carbon quantum dot corrosion inhibitor has excellent water solubility.

[0027] The application of the nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor prepared by the present invention in the corrosion protection of metal substrate surfaces. The metal substrate includes but is not limited to any one of steel, copper, iron and their alloys. During application, the surface of the metal substrate is immersed in a solution containing the nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor, thereby achieving protection of the metal substrate. The metal substrate can be used in the petroleum industry, marine industry, national defense industry, machinery industry, papermaking industry, transportation platforms, etc. The nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor prepared by the present invention can be used in steel, chemical industry, petroleum, electric power, papermaking, oil refining, shipping, storage, transportation and other fields.

[0028] Furthermore, after the metal substrate is immersed in the HCl solution of the nitrogen, phosphorus and fluorine ternary doped carbon quantum dots corrosion inhibitor for 24 hours, the impedance can still reach 10 2 -10 3 order of magnitude, and the corrosion current density is as low as 10 -5 -10 -6 A / cm 2 Compared with the solution without corrosion inhibitor, the low-frequency impedance modulus increased by 1-2 orders of magnitude and the corrosion current density decreased by 1-2 orders of magnitude.

[0029] The present invention will be further described below with reference to specific embodiments.

[0030] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0031] Comparative Example 1

[0032] First, the Q235 carbon steel substrate was degreased. A copper wire was then soldered to the carbon steel surface, sealed in AB glue (3:1), leaving only a 1cm × 1cm test surface exposed. The working surface was then polished for 20 minutes using 400#, 800#, 1200#, and 1500# sandpaper, respectively. Finally, it was rinsed with ethanol and dried. After treatment, the carbon steel substrate was used as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet as the counter electrode for electrochemical testing. After immersion in 1M HCl solution for 24 hours, the low-frequency impedance was 24Ωcm. 2 , the corrosion current density is 2.2×10-4 A / cm 2 .

[0033] Comparative Example 2

[0034] First, the T2 copper substrate was degreased. A copper wire was then soldered to the T2 copper surface, sealed in AB glue (3:1), leaving only a 1cm × 1cm test surface exposed. The working surface was then polished for 20 minutes using 400#, 800#, 1200#, and 1500# sandpaper, respectively. Finally, it was rinsed with ethanol and dried. After treatment, the T2 copper substrate was used as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet as the counter electrode for electrochemical testing. After immersion in 1M HCl solution for 24 hours, the low-frequency impedance was 13Ωcm. 2 , the corrosion current density is 2.9×10 -4 A / cm 2 .

[0035] Comparative Example 3

[0036] First, the Q235 carbon steel substrate was degreased. A copper wire was then soldered to the carbon steel surface, sealed in AB glue (3:1), leaving only a 1cm × 1cm test surface exposed. The working surface was then polished for 20 minutes using 400#, 800#, 1200#, and 1500# sandpaper, respectively. Finally, it was rinsed with ethanol and dried. After treatment, the carbon steel substrate was used as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet as the counter electrode for electrochemical testing. After immersion in 3.5% NaCl solution for 24 hours, the low-frequency impedance was 47Ωcm. 2 , the corrosion current density is 1.6×10 -5 A / cm 2 .

[0037] Comparative Example 4

[0038] 2g of tryptophan was dissolved in 60mL of deionized water and then transferred to a reactor. The heating temperature was set to 200°C and the heating time was 6h. After the reaction was completed, the solution was stirred for 10min and then ultrasonically treated for 10min, then filtered and centrifuged. The speed during the centrifugation was 8000r / min, and then dialyzed. The molecular weight of the dialysis bag was 1KD. Finally, the dialysate was placed in a vacuum drying oven and dried for 30h at 60°C to obtain a nitrogen-doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare an inhibitor solution with a concentration of 10, 20, 30, and 40mg / L. The electrode prepared in Comparative Example 1 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained are shown in Table 1. Compared with Comparative Example 1, the low-frequency impedance modulus of carbon steel increased by 2.4, 3.7, 7.5, and 10.1 times, respectively, compared with before the addition of corrosion inhibitor; from the perspective of corrosion inhibition efficiency, it showed a lower protection efficiency.

[0039] Table 1 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0040] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 82 113 204 267 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[9.1×10 -5 ]]> <![CDATA[8.4×10 -5 ]]> <![CDATA[8.1×10 -5 ]]> <![CDATA[6.8×10 -5 ]]> Corrosion inhibition efficiency (%) 59 62 63 69

[0041] Comparative Example 5

[0042] 2g of tetrafluorobenzoquinone was dissolved in 60mL of deionized water and then transferred to a reactor. The heating temperature was set to 200°C and the heating time was 6h. After the reaction was completed, the solution was stirred for 10min and then ultrasonically treated for 10min, then filtered and centrifuged. The speed during the centrifugation was 8000r / min, and then dialyzed. The molecular weight of the dialysis bag was 1KD. Finally, the dialysate was placed in a vacuum drying oven and dried for 30h at 60°C to obtain a fluorine-doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare an inhibitor solution with a concentration of 10, 20, 30, and 40mg / L. The electrode prepared in Comparative Example 1 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained were shown in Table 2. Compared with Comparative Example 1, the low-frequency impedance modulus of carbon steel increased by 3.3, 4.5, 8.8, and 10.9 times, respectively, compared with that before adding the corrosion inhibitor.

[0043] Table 2 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0044] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 104 132 234 285 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[8.3×10 -5 ]]> <![CDATA[7.2×10 -5 ]]> <![CDATA[6.5×10 -5 ]]> <![CDATA[5.8×10 -5 ]]> Corrosion inhibition efficiency (%) 62 67 70 74

[0045] Comparative Example 6

[0046] 2g tryptophan and 0.1g phosphoric acid were dissolved in 60mL deionized water and subsequently transferred to a reactor. The heating temperature was set to 200°C and the heating time was 6h. After the reaction was completed, the solution was stirred for 10min and then ultrasonically treated for 10min, then filtered and centrifuged. The speed during the centrifugation was 8000r / min, and then dialyzed. The molecular weight of the dialysis bag was 1KD. Finally, the dialysate was placed in a vacuum drying oven and dried for 30h at 60°C to obtain a nitrogen-phosphorus-doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare an inhibitor solution with a concentration of 10, 20, 30, and 40mg / L. The electrode prepared in Comparative Example 1 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained are shown in Table 3. Compared with the control example, the low-frequency impedance modulus of carbon steel increased by 3.5, 4.2, 7.7 and 10.3 times respectively compared with that before adding corrosion inhibitor.

[0047] Table 3 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0048] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 109 124 208 271 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[6.5×10 -5 ]]> <![CDATA[5.1×10 -5 ]]> <![CDATA[4.7×10 -5 ]]> <![CDATA[4.2×10 -5 ]]> Corrosion inhibition efficiency (%) 70 77 79 81

[0049] Comparative Example 7

[0050] 2g tryptophan and 0.1g tetrafluorobenzoquinone were dissolved in 60mL deionized water and subsequently transferred to a reactor, with the heating temperature set to 200°C and the heating time set to 6h. After the reaction was completed, the solution was stirred for 10min and then ultrasonically treated for 10min, then filtered and centrifuged. The speed during the centrifugation was 8000r / min, and then dialyzed, with a molecular weight of 1KD. Finally, the dialysate was placed in a vacuum drying oven and dried for 30h at 60°C to obtain a nitrogen-fluorine-doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare an inhibitor solution with a concentration of 10, 20, 30, 40mg / L. The electrode prepared in Comparative Example 1 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained were shown in Table 4. Compared with Comparative Example 1, the low-frequency impedance modulus of carbon steel increased by 3.8, 6.3, 8.1, and 11.2 times, respectively, compared with before the addition of corrosion inhibitor.

[0051] Table 4 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0052] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 114 176 218 292 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[5.9×10 -5 ]]> <![CDATA[4.8×10 -5 ]]> <![CDATA[4.2×10 -5 ]]> <![CDATA[3.9×10 -5 ]]> Corrosion inhibition efficiency (%) 73 78 81 82

[0053] Comparative Example 8

[0054] 0.2g of tetrafluorobenzoquinone and 0.1g of phosphoric acid were dissolved in 60mL of deionized water and subsequently transferred to a reactor. The heating temperature was set to 200°C and the heating time was 6h. After the reaction was completed, the solution was stirred for 10min and then ultrasonically treated for 10min, then filtered and centrifuged. The speed during the centrifugation was 8000r / min, and then dialyzed. The molecular weight of the dialysis bag was 1KD. Finally, the dialysate was placed in a vacuum drying oven and dried for 30h at 60°C to obtain a phosphorus-fluorine-doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare an inhibitor solution with a concentration of 10, 20, 30, 40mg / L. The electrode prepared in Comparative Example 1 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained are shown in Table 5. Compared with Comparative Example 1, the low-frequency impedance modulus of carbon steel increased by 6.8, 8.8, 13.5, and 16.3 times, respectively, compared with before the addition of corrosion inhibitor.

[0055] Table 5 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0056] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 186 236 347 415 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[5.5×10 -5 ]]> <![CDATA[4.6×10 -5 ]]> <![CDATA[3.9×10 -5 ]]> <![CDATA[3.4×10 -5 ]]> Corrosion inhibition efficiency (%) 75 79 82 85

[0057] Comparative Example 9

[0058] 2g of tryptophan, 0.1g of phosphoric acid, and 0.2g of tetrafluoro-p-benzoquinone were dissolved in 60mL of deionized water, and then prepared into corrosion inhibitor solutions at concentrations of 10, 20, 30, and 40mg / L, respectively. The electrode prepared in Comparative Example 1 was placed in these solutions for electrochemical measurements. After immersion for 24 hours, the final low-frequency impedance, corrosion current density, and corrosion inhibition efficiency are shown in Table 6. Compared with Comparative Example 1, the low-frequency impedance modulus of carbon steel increased by 0.96, 2.0, 2.9, and 4.3 times, respectively, compared to the state without the addition of the corrosion inhibitor.

[0059] Table 6 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0060] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 47 72 94 126 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[1.6×10 -4 ]]> <![CDATA[1.3×10 -4 ]]> <![CDATA[1.0×10 -4 ]]> <![CDATA[0.96×10 -4 ]]> Corrosion inhibition efficiency (%) 27 41 53 56

[0061] Example 1

[0062] 2g tryptophan, 0.1g phosphoric acid and 0.2g tetrafluorobenzoquinone were dissolved in 60mL deionized water, and then transferred to a reactor. The heating temperature was set to 200℃ and the heating time was 6h. After the reaction was completed, the solution was stirred for 10min and then ultrasonicated for 10min, then filtered and centrifuged. The speed during the centrifugation process was 8000r / min, and then dialyzed. The molecular weight of the dialysis bag was 1KD. Finally, the dialyzate was placed in a vacuum drying oven and dried for 30h at a temperature of 60℃ to obtain a ternary doped carbon quantum dot corrosion inhibitor. The high-resolution morphology of the corrosion inhibitor is shown in FIG. Figure 1 As shown, the results show that the nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor has excellent dispersibility and a size of about 2-8 nm. . A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare corrosion inhibitor solutions with concentrations of 10, 20, 30, and 40 mg / L. The electrode prepared in Comparative Example 1 was placed in the above solution for electrochemical measurement. After soaking for 24 hours, the final low-frequency impedance, corrosion current density, and corrosion inhibition efficiency are shown in Table 7. Compared with Comparative Example 1, the low-frequency impedance modulus of carbon steel increased by 31, 50.8, 74.2, and 95.5 times, respectively, compared with that before the corrosion inhibitor was added.

[0063] Table 7 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0064] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 768 1243 1805 2317 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[2.7×10 -5 ]]> <![CDATA[1.4×10 -5 ]]> <![CDATA[0.76×10 -5 ]]> <![CDATA[0.32×10 -5 ]]> Corrosion inhibition efficiency (%) 88 94 97 99

[0065] Example 2

[0066] 2g of tryptophan, 0.1g of phosphoric acid and 0.2g of tetrafluorobenzoquinone were dissolved in 60mL of deionized water and then transferred to a reactor. The heating temperature was set to 160°C and the heating time was 6h. After the reaction was completed, the solution was stirred for 10min and then ultrasonicated for 10min, then filtered and centrifuged. The speed during the centrifugation was 8000r / min, and then dialyzed. The molecular weight of the dialysis bag was 1KD. Finally, the dialyzate was placed in a vacuum drying oven and dried for 30h at 60°C to obtain a ternary doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare corrosion inhibitor solutions with concentrations of 10, 20, 30, and 40mg / L. The electrode prepared in Comparative Example 1 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained are shown in Table 8. Compared with Example 1, as the reaction temperature was reduced to 160°C, the low-frequency impedance of carbon steel decreased.

[0067] Table 8 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0068]

[0069]

[0070] Example 3

[0071] 2g of tryptophan, 0.1g of phosphoric acid and 0.2g of tetrafluorobenzoquinone were dissolved in 60mL of deionized water and then transferred to a reactor. The heating temperature was set to 240°C and the heating time was 6h. After the reaction was completed, the solution was stirred for 10min and then ultrasonicated for 10min, then filtered and centrifuged. The speed during the centrifugation was 8000r / min, and then dialyzed. The molecular weight of the dialysis bag was 1KD. Finally, the dialyzate was placed in a vacuum drying oven and dried for 30h at 60°C to obtain a ternary doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare corrosion inhibitor solutions with concentrations of 10, 20, 30, and 40mg / L. The electrode prepared in Comparative Example 1 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained are shown in Table 9. Compared with Table 7, as the reaction temperature was reduced to 240°C, the low-frequency impedance of carbon steel showed a certain degree of decrease. Compared with Examples 1 and 2, as the reaction temperature increases, the corrosion inhibition efficiency of the ternary doped carbon quantum dot corrosion inhibitor first increases and then decreases.

[0072] Table 9 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0073] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 612 1078 1538 1976 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[3.8×10 -5 ]]> <![CDATA[2.4×10 -5 ]]> <![CDATA[0.94×10 -5 ]]> <![CDATA[0.45×10 -5 ]]> Corrosion inhibition efficiency (%) 83 89 96 98

[0074] Example 4

[0075] 2g tryptophan, 0.2g phosphoric acid and 0.1g tetrafluorobenzoquinone were dissolved in 60mL deionized water and subsequently transferred to a reactor. The heating temperature was set to 200°C and the heating time was 4h. After the reaction was completed, the solution was stirred for 30min and then ultrasonicated for 30min, then filtered and centrifuged. The speed during the centrifugation was 18000r / min, and then dialyzed. The molecular weight of the dialysis bag was 6KD. Finally, the dialysate was placed in a vacuum drying oven and dried for 60h at 90°C to obtain a ternary doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare an inhibitor solution with a concentration of 10, 20, 30, 40mg / L. The electrode prepared in Comparative Example 2 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density and corrosion inhibition efficiency finally obtained were shown in Table 10.

[0076] Table 10 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0077] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 512 885 1327 1678 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[4.3×10 -5 ]]> <![CDATA[2.6×10 -5 ]]> <![CDATA[1.8×10 -5 ]]> <![CDATA[0.97×10 -5 ]]> Corrosion inhibition efficiency (%) 85 91 94 97

[0078] Example 5

[0079] 2g tryptophan, 0.2g phosphoric acid and 0.1g tetrafluorobenzoquinone were dissolved in 60mL deionized water and then transferred to a reactor. The heating temperature was set to 200°C and the heating time was 6h. After the reaction was completed, the solution was stirred for 30min and then ultrasonicated for 30min, then filtered and centrifuged. The speed during the centrifugation was 18000r / min, and then dialyzed. The molecular weight of the dialysis bag was 6KD. Finally, the dialyzate was placed in a vacuum drying oven and dried for 60h at 90°C to obtain a ternary doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare corrosion inhibitor solutions with concentrations of 10, 20, 30, and 40mg / L. The electrode prepared in Comparative Example 2 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained are shown in Table 11. Compared with Example 4, as the reaction time was extended to 6h, the impedance of T2 copper showed a certain degree of increase.

[0080] Table 11 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0081] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 873 1157 1735 2017 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[2.1×10 -5 ]]> <![CDATA[1.6×10 -5 ]]> <![CDATA[0.94×10 -5 ]]> <![CDATA[0.42×10 -5 ]]> Corrosion inhibition efficiency (%) 93 95 97 99

[0082] Example 6

[0083] 2g tryptophan, 0.2g phosphoric acid and 0.1g tetrafluorobenzoquinone were dissolved in 60mL deionized water and then transferred to a reactor. The heating temperature was set to 200°C and the heating time was 8h. After the reaction was completed, the solution was stirred for 30min and then ultrasonicated for 30min, then filtered and centrifuged. The speed during the centrifugation was 18000r / min, and then dialyzed. The molecular weight of the dialysis bag was 6KD. Finally, the dialyzate was placed in a vacuum drying oven and dried for 60h at 90°C to obtain a ternary doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 1M HCl solution to prepare corrosion inhibitor solutions with concentrations of 10, 20, 30, and 40mg / L. The electrode prepared in Comparative Example 2 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density, and corrosion inhibition efficiency finally obtained are shown in Table 12. Compared with Example 5, as the reaction time was extended to 8h, the impedance of T2 copper decreased successively. Comparing Examples 4, 5, and 6, the corrosion inhibition efficiency of the ternary-doped carbon quantum dot corrosion inhibitor first increases and then decreases with increasing reaction time. Compared with Comparative Example 2, the corrosion current density of T2 copper decreased by 1-2 orders of magnitude after adding the corrosion inhibitor to the HCl solution, and the corrosion inhibition efficiency was greatly improved.

[0084] Table 12 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0085] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 756 1029 1541 1893 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[2.5×10 -5 ]]> <![CDATA[2.1×10 -5 ]]> <![CDATA[1.06×10 -5 ]]> <![CDATA[0.57×10 -5 ]]> Corrosion inhibition efficiency (%) 91 93 96 98

[0086] Example 7

[0087] 2g tryptophan, 0.02g phosphoric acid and 0.02g tetrafluorobenzoquinone were dissolved in 60mL deionized water and subsequently transferred to a reactor, with the heating temperature set to 200°C and the heating time set to 6h. After the reaction was completed, the solution was stirred for 20min and then ultrasonically treated for 20min, then filtered and centrifuged. The speed during the centrifugation was 12000r / min, and then dialyzed, with a molecular weight of 3KD. Finally, the dialyzate was placed in a vacuum drying oven and dried for 40h at 80°C to obtain a ternary doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 3.5% NaCl solution, and an inhibitor solution with a concentration of 10, 20, 30, 40mg / L was configured. The electrode prepared in Comparative Example 3 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density and corrosion inhibition efficiency finally obtained were shown in Table 13.

[0088] Table 13 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0089] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 485 796 1214 1438 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[3.2×10 -5 ]]> <![CDATA[3.1×10 -5 ]]> <![CDATA[2.4×10 -5 ]]> <![CDATA[1.3×10 -5 ]]> Corrosion inhibition efficiency (%) 75 77 82 90

[0090] Example 8

[0091] 2g tryptophan, 0.2g phosphoric acid and 0.2g tetrafluorobenzoquinone were dissolved in 60mL deionized water and subsequently transferred to a reactor, with the heating temperature set to 200°C and the heating time set to 6h. After the reaction was completed, the solution was stirred for 20min and then ultrasonically treated for 20min, then filtered and centrifuged. The speed during the centrifugation was 12000r / min, and then dialyzed, with a molecular weight of 3KD. Finally, the dialyzate was placed in a vacuum drying oven and dried for 40h at 80°C to obtain a ternary doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 3.5% NaCl solution to prepare an inhibitor solution with a concentration of 10, 20, 30, 40mg / L. The electrode prepared in Comparative Example 3 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density and corrosion inhibition efficiency finally obtained were shown in Table 14. Compared with Example 7, as the mass ratio of phosphoric acid to tryptophan and the mass ratio of tetrafluoro-p-benzoquinone to tryptophan increase, the impedance of carbon steel increases sharply.

[0092] Table 14 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0093] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 1562 2014 2883 3579 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[0.88×10 -5 ]]> <![CDATA[0.42×10 -5 ]]> <![CDATA[0.35×10 -5 ]]> <![CDATA[0.21×10 -5 ]]> Corrosion inhibition efficiency (%) 93 97 97 98

[0094] Example 9

[0095] 2g tryptophan, 0.4g phosphoric acid and 0.4g tetrafluorobenzoquinone were dissolved in 60mL deionized water and subsequently transferred to a reactor, with the heating temperature set to 200°C and the heating time set to 6h. After the reaction was completed, the solution was stirred for 20min and then ultrasonically treated for 20min, then filtered and centrifuged. The speed during the centrifugation was 12000r / min, and then dialyzed, with a molecular weight of 3KD. Finally, the dialyzate was placed in a vacuum drying oven and dried for 40h at 80°C to obtain a ternary doped carbon quantum dot corrosion inhibitor. A certain amount of corrosion inhibitor was then added to a 3.5% NaCl solution to prepare an inhibitor solution with a concentration of 10, 20, 30, 40mg / L. The electrode prepared in Comparative Example 3 was placed in the above solution for electrochemical measurement. After soaking for 24h, the low-frequency impedance, corrosion current density and corrosion inhibition efficiency finally obtained were shown in Table 15. Compared with Example 8, the impedance of carbon steel decreased as the mass ratios of phosphoric acid to tryptophan and tetrafluoro-p-benzoquinone to tryptophan increased. Comparisons with Examples 7, 8, and 9 revealed that the corrosion inhibition efficiency of the ternary-doped carbon quantum dot corrosion inhibitor first increased and then decreased with increasing mass ratios. Compared with Comparative Example 3, the corrosion current density of carbon steel decreased by 1-2 orders of magnitude after adding the corrosion inhibitor to the NaCl solution, and the corrosion inhibition efficiency was significantly improved.

[0096] Table 15 Low-frequency impedance, corrosion current density and corrosion inhibition efficiency of corrosion inhibitor solutions with different concentrations

[0097] Corrosion inhibitor solution concentration (mg / L) 10 20 30 40 <![CDATA[Low-frequency impedance (Ωcm 2 )]]> 1377 1632 2268 2814 <![CDATA[Corrosion current density (A / cm 2 )]]> <![CDATA[0.86×10 -5 ]]> <![CDATA[0.77×10 -5 ]]> <![CDATA[0.61×10 -5 ]]> <![CDATA[0.52×10 -5 ]]> Corrosion inhibition efficiency (%) 93 94 95 96

[0098] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor, characterized in that: A mixed reaction system of tryptophan and / or tryptophan derivatives, tetrafluoro-p-benzoquinone, phosphoric acid and a solvent is subjected to a hydrothermal reaction at 160-240° C. for 4-8 hours to obtain a nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor.

2. The preparation method according to claim 1, wherein: The tryptophan derivatives include 5-hydroxytryptophan and / or 1-methyl-tryptophan, and the solvent includes water and / or acid.

3. The preparation method according to claim 1, wherein: The mass ratio of the phosphoric acid to tryptophan and / or tryptophan derivatives is 1:100-20:100; the mass ratio of the tetrafluoro-p-benzoquinone to tryptophan and / or tryptophan derivatives is 1:100-20:

100.

4. The preparation method according to claim 1, wherein: After the hydrothermal reaction is completed, the obtained solution is stirred, ultrasonicated, filtered, centrifuged, dialyzed, and dried. The stirring time is 10-30 minutes, the ultrasonic treatment time is 10-30 minutes, the centrifugal speed is 8000-18000 r / min, the molecular weight of the dialysis bag used in the dialysis treatment is 1-6KD, and the drying temperature is 60-90°C for 30-60 hours.

5. A nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor prepared by the preparation method according to claims 1 to 4.

6. The nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor according to claim 5, characterized in that: The size of the corrosion inhibitor is 1-20 nm.

7. The nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor according to claim 5, characterized in that: The solubility of the corrosion inhibitor in water is 10-250 mg / mL.

8. Use of the nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor prepared by the preparation method according to claims 1 to 4 in the corrosion protection of metal substrate surfaces.

9. The use according to claim 8, characterized in that: The metal substrate includes any one of steel, copper, iron and alloys thereof.

10. The use according to claim 9, characterized in that: The surface of the metal substrate is immersed in a solution containing nitrogen, phosphorus and fluorine ternary doped carbon quantum dot corrosion inhibitor.

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