Carbon steel assembled modified amino acid corrosion inhibition film and preparation and application thereof

Abstract

The present application relates to the technical field of metal corrosion and protection, and relates to a carbon steel assembled modified amino acid corrosion inhibitor film and preparation and application thereof, a modified amino acid compound is prepared in a modified manner, and an amino acid assembly film is formed on the surface of the carbon steel through a gas phase self-assembly method, the volatility of the amino acid is improved, and the corrosion inhibition effect on the carbon steel is improved, which has great significance for the development of amino acid corrosion inhibitors. Compared with the prior art, the present application has the advantages of improving the volatility of the amino acid, improving the compactness and stability of the assembly film on the surface of the carbon steel, and effectively improving the corrosion resistance of the carbon steel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal corrosion and protection, and particularly relates to a carbon steel assembled modified amino acid corrosion inhibitor film and preparation and application thereof. BACKGROUND

[0002] Carbon steel has good mechanical properties, is easy to process, and the like, and thus becomes a key material for industrial and engineering applications, and is widely applied to the fields of building, automobile, ship, and petrochemical industry. However, corrosion of the carbon steel will cause serious and inevitable loss, not only causing great waste of resources, but also causing great safety hazards. The corrosion inhibitor is a commonly used anticorrosion method, has characteristics of high protection efficiency, wide adaptability, and low price, and the like, and with deepening of research, the gas-phase corrosion inhibitor is gradually widely applied. However, some widely applied gas-phase corrosion inhibitors, such as dicyclohexylamine nitrite, are highly toxic, and will cause great damage to the environment and ecology, and thus there is an urgent need to develop efficient, non-toxic, and economical environment-friendly gas-phase corrosion inhibitors.

[0003] There are extensive reports on the development of environmentally friendly gas-phase corrosion inhibitors from natural plants, such as extracts of orange leaves and seeds, and extracts of rapeseed cakes. Chinese Patent Application CN102372681A discloses a natural plant extract modified compounded corrosion inhibitor, which comprises the following components: glycidyl ester polymer and 2-phosphonobutane-1,2,4-tricarboxylic acid. The glycidyl ester polymer is the product formed by copolymerization of sugarcane leaf extract and glycidyl methacrylate. The corrosion inhibitor can play a synergistic effect, improve the high-temperature resistance of the corrosion inhibitor, and achieve better corrosion inhibition effect by modifying the natural plant extract and compounding it with 2-phosphonobutane-1,2,4-tricarboxylic acid. However, the cost of plant extract is too high, the method is not convenient, and it is not conducive to the popularization and application of production. Chinese Patent Application CN112680190A discloses a plant type composite high-efficiency corrosion inhibitor, which is made of the following raw materials by mass percentage: plant 12-66.0%, sodium molybdate 5.0-16.0%, sodium gluconate 1.5-12%, sodium tartrate 3.5-25%, zinc sulfate 0-23%, and potassium dihydrogen phosphate 4.0-23.0%. The invention can have a corrosion inhibition effect on chlorate-type snow-melting agent. After adding the corrosion inhibitor, the corrosion of chlorate-type snow-melting agent on metal and concrete and the harm to vegetation can be reduced. However, the operation process of this patent is complicated and the cost is too high. Chinese Patent Application CN115233226A discloses a carbon steel surface composite amino acid assembly film and its preparation method and application, which comprises the following mass percentage of substances: synergist 50-55%; amino acid 45-50%. The invention improves the volatility of amino acid by compounding and synergizing. A self-assembled film is formed on the surface of steel by gas-phase self-assembly, improving the corrosion resistance of steel materials. However, the added reagent plays a similar role as an auxiliary agent and does not form a chemical bond with the amino acid structure, which affects the firmness and performance. SUMMARY

[0004] The purpose of the present application is to overcome the defects of the prior art and provide a carbon steel assembly modified amino acid corrosion inhibitor with simple operation method and excellent performance. The present application prepares a modified amino acid corrosion inhibitor by modification and forms an amino acid corrosion film on the surface of carbon steel by gas-phase self-assembly, improving the volatility of amino acid and the corrosion inhibition effect on carbon steel, which has great significance for the development of amino acid corrosion inhibitors.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] A modified amino acid corrosion inhibitor for carbon steel, comprising the following steps:

[0007] The amino acid is mixed with an alkaline agent and reacted to obtain an intermediate product. The intermediate product is mixed with a synergist and reacted to obtain the modified amino acid corrosion inhibitor.

[0008] Further, the amino acid is a non-polar amino acid, preferably alanine.

[0009] Further, the alkaline-binding agent is a binary or ternary weak acid, preferably phosphoric acid.

[0010] Further, the synergist is a long-chain fatty amine, preferably a long-chain fatty amine with a carbon atom number greater than or equal to 8.

[0011] Further, the modified amino acid corrosion inhibitor has the following mass percentage of each component:

[0012] Amino acid 60-70%;

[0013] Alkaline-binding agent 5-10%;

[0014] Synergist 20-35%.

[0015] A modified amino acid corrosion inhibitor for carbon steel in metal corrosion prevention, characterized in that it comprises the following steps:

[0016] The prepared modified amino acid corrosion inhibitor is placed at the bottom of a sealed container, and the carbon steel to be treated is placed above the modified amino acid corrosion inhibitor in the sealed container. After heating, a modified amino acid corrosion film is obtained for carbon steel assembly.

[0017] Further, the heating temperature is 40-80℃, and the time is 12-24h

[0018] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0019] (1) The amino acid is modified in the present application. The alkaline-binding agent (binary or ternary weak acid) reacts with -NH2 in the amino acid, and the synergist (long-chain fatty amine) continues to react with -COOH to obtain a modified amino acid. Unlike simply adding additives to amino acid, the present application introduces long-chain, heteroatoms, acid ions, etc. into the structure of amino acid, effectively improving the volatility of amino acid, further improving the compactness and stability of the carbon steel surface assembly film, thereby effectively improving the corrosion resistance of carbon steel.

[0020] (2) The present application forms a modified amino acid assembly film on the surface of carbon steel by gas phase self-assembly. The raw materials used are simple, the operation is convenient, and there is no pollution to the environment. The application method and range of amino acid corrosion inhibitors are expanded. At the same time, the preparation method of the corrosion inhibitor in the present application is universal and can be applied to different types of amino acids. The method of assembling the corrosion film is also simple. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1Chemical reaction formula of the synthesis reaction process of the modified alanine complex in Example 1, Example 2 and Example 3 of the present application;

[0022] Figure 2 Infrared test result graph of the raw material and the modified alanine complex in Example 1 of the present application;

[0023] Figure 3 Infrared test result graph of the raw material and the modified alanine complex in Example 2 of the present application;

[0024] Figure 4 Infrared test result graph of the raw material and the modified alanine complex in Example 3 of the present application;

[0025] Figure 5 Volatilization reduction test result graph of the modified alanine complex in Example 1, Example 2 and Example 3 of the present application;

[0026] Figure 6 Gas phase corrosion inhibition ability test result graph of the carbon steel sample and the blank carbon steel sample in Example 1, Example 2 and Example 3 of the present application;

[0027] Figure 7 Equivalent circuit diagram of the electrochemical test of the electrode of the carbon steel sample and the blank carbon steel sample in Example 1, Example 2 and Example 3 of the present application in the simulated atmospheric corrosion aqueous solution;

[0028] Figure 8 Impedance spectrum diagram of the electrochemical test of the electrode of the carbon steel sample and the blank carbon steel sample in Example 1, Example 2 and Example 3 of the present application in the simulated atmospheric corrosion aqueous solution;

[0029] Figure 9 Polarization curve diagram of the electrochemical test of the electrode of the carbon steel sample and the blank carbon steel sample in Example 1, Example 2 and Example 3 of the present application in the simulated atmospheric corrosion aqueous solution. DETAILED DESCRIPTION

[0030] The present application will be described in detail below with reference to the accompanying drawings and specific examples.

[0031] The following examples are implemented on the basis of the above technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0032] The following are more detailed implementation cases, which further illustrate the technical solutions of the present application and the technical effects that can be obtained.

[0033] In the following examples, if there is no special description of raw material reagents or processing technology, it means that they are all conventional market products or conventional processing technology in the art.

[0034] Example 1

[0035] The present example provides a carbon steel assembled modified amino acid corrosion inhibitor film and a preparation method thereof.

[0036] First, a modified amino acid corrosion inhibitor was prepared: 2.6727 g of alanine (0.03 mol) was weighed into a 150 mL three-necked flask, 1.1529 g of 85% phosphoric acid aqueous solution (0.01 mol H3PO4) was added dropwise, stirred by a mechanical stirrer at room temperature for 5 min, 3.8772 g of di-n-butylamine (0.03 mol) was added dropwise, and stirring was continued until the reaction exothermic ended (see equation of reaction process Figure 1 ), the solid was taken out and placed in a 40°C air-drying oven for drying for 6 h to obtain a modified amino acid corrosion inhibitor. The modified amino acid corrosion inhibitor was tested by infrared spectroscopy in the test range of 400 cm -1 to 4000 cm -1 at room temperature by KBr tabletting, and the test results are shown in Figure 2 .

[0037] Then, a carbon steel sample of surface assembled modified alanine corrosion inhibitor film was prepared:

[0038] 0.1 g of the modified alanine compound prepared above was placed at the bottom of a 1 L wide-mouth bottle, and a carbon steel test piece (10# carbon steel test piece: 10 mm x 10 mm x 3 mm; Φ35 x 10 mm, purchased from Tianjin Binhai Jin Yong Metal Test Piece Co., Ltd.). The carbon steel test piece was polished and polished by using a metallographic sandpaper, then washed with 10 mL of anhydrous ethanol and deionized water for 3 times in sequence, and then placed at the top of the container and 3 cm away from the modified alanine compound. After the placement was completed, the container was sealed. The sealed container was placed in a 40°C air-drying oven for 24 h, and after the end, a carbon steel sample of surface assembled modified alanine corrosion inhibitor film was obtained.

[0039] Example 2

[0040] The present example provides a carbon steel assembled modified amino acid corrosion inhibitor film and a preparation method thereof.

[0041] The difference between the present example and Example 1 is that the amount of di-n-butylamine is different. In the present example, the amount of di-n-butylamine is 1.9386 g, and the other steps are the same as those in Example 1. The modified amino acid corrosion inhibitor prepared was tested by infrared spectroscopy in the test range of 400 cm -1 to 4000 cm -1 at room temperature by KBr tabletting, and the test results are shown in Figure 3 .

[0042] Example 3

[0043] This embodiment provides a carbon steel-assembled modified amino acid corrosion inhibitor film and its preparation method:

[0044] The difference between this embodiment and Example 1 lies in the amount of di-n-butylamine used. In this embodiment, the amount of di-n-butylamine used is 1.2924 g. All other steps are the same as in Example 1. Tableting was performed at room temperature using KBr compression at 400 cm⁻¹. -1 Up to 4000cm -1 The modified amino acid corrosion inhibitor was tested by infrared spectroscopy within the test range, and the test results are shown in the figure. Figure 4 .

[0045] Test experiment:

[0046] 1. Volatilization rate test:

[0047] 2g of the modified alanine complexes prepared in Examples 1, 2, and 3 were evenly spread into 5cm diameter petri dishes. The petri dishes were then placed in a 40℃ oven for 72 hours. Every 24 hours, the petri dishes were removed, weighed, and the evaporation rate was calculated. To ensure data accuracy, three parallel samples were taken for each experiment. The experimental results are shown below. Figure 5 .

[0048] The volatile rate is calculated using the following formula:

[0049]

[0050] Where C% is the evaporation rate of the corrosion inhibitor, w0 is the initial mass of the corrosion inhibitor, and w0 is the mass of the corrosion inhibitor after a certain period of evaporation.

[0051] like Figure 5 As shown, the volatilization rate of the modified alanine complexes prepared in Examples 1 and 2 was greatly improved compared with that of the modified alanine complex prepared in Example 3. In the first 24 hours, the volatilization rate of the modified alanine complex prepared in Example 1 was similar to that of the modified alanine complex prepared in Example 2. After 24 hours, the volatilization performance of the alanine ternary complex in Example 1 was stronger.

[0052] 2. Corrosion inhibition effect test:

[0053] An aluminum tube (outer diameter d = 16 mm, wall thickness 1.5 mm, length 114 mm) was inserted into the rubber stopper of a 500 mL wide-mouth bottle. Carbon steel samples of surface-modified alanine-assembled films prepared in Examples 1, 2, and 3 were placed at the bottom of the wide-mouth bottle, respectively. 10 mL of a 35% (w / w) glycerol aqueous solution was added to the bottle. After placing the bottle at 20°C for 20 h, the aluminum tube was filled with water at 0°C-2°C, and the bottle was returned to its original position for 3 h. Afterward, the bottle was gently wiped with degreased cotton and dried. The corrosion inhibition effect was observed and evaluated. The experimental results are shown in [Figure number missing]. Figure 6 .

[0054] like Figure 6 As shown in the figure, 1 is a blank carbon steel sample without surface modification by the alanine assembly film, and 2, 3, and 4 are carbon steel samples of Example 1, Example 2, and Example 3, respectively. As can be seen from the figure, the carbon steel sample of Example 2 has fewer corrosion spots on its surface, indicating that the corrosion inhibition ability of the modified amino acid assembly film of Example 2 is stronger than that of the modified amino acid assembly films of Example 1 and Example 3.

[0055] 3. Electrochemical impedance spectroscopy (EIS) test:

[0056] Carbon steel samples (10 mm × 10 mm × 3 mm) with surface-modified alanine-coated films prepared in Examples 1, 2, and 3 were used as working electrodes. Blank carbon steel samples without alanine-coated film modification were used as comparative examples. Electrochemical impedance spectroscopy (EIS) was performed using a three-electrode system, with a platinum electrode as the auxiliary electrode (CE) and a saturated calomel electrode (SCE) as the reference electrode (RE). The electrolyte used was simulated atmospheric corrosion water (100 mg / L sulfate, 100 mg / L chloride, and 100 mg / L bicarbonate ions). The EIS was measured using a 5 mV sinusoidal signal with a scan frequency from 100 kHz to 0.01 Hz. Polarization curves were scanned at a rate of 1 mV / s.

[0057] like Figure 7 As shown, R s R represents the resistance of the solution. f and R ct CPE represents the resistance and charge transfer resistance of the assembled film, respectively. f and CPE dl These are constant phase elements, representing surface-film capacitance and double-layer capacitance, respectively, and polarization resistance (R). p It can be obtained from the following formula:

[0058] R P ≈R f +R ct

[0059] Corrosion inhibition efficiency η R Calculate using the following formula:

[0060]

[0061] Among them, R p The polarization resistance R of the carbon steel sample electrode with the corrosion inhibition film is given. p,0 The polarization resistance is shown for the blank carbon steel sample electrode. The electrochemical impedance spectroscopy results of the carbon steel sample electrodes from Examples 1, 2, and 3 in simulated atmospheric corrosion aqueous solutions are shown below. Figure 8 See the electrochemical equivalent circuit diagram. Figure 7The electrochemical impedance fitting parameters are shown in Table 1.

[0062] Table 1. Electrochemical impedance fitting parameters of carbon steel sample electrodes from Examples 1, 2, 3, and the comparative example in simulated atmospheric corrosion aqueous solution.

[0063]

[0064] As shown in Table 1, the polarization resistance (R) of the carbon steel sample electrodes in Examples 1, 2, and 3 relative to the comparative carbon steel sample electrode is... p All three methods showed improvement, indicating that Examples 1, 2, and 3 all provided some protection for carbon steel. Specifically, the carbon steel sample electrode R in Example 2... p The R value is much larger than that of the carbon steel sample electrodes in Examples 1 and 3. p The value indicates that the modified amino acid assembly film of Example 2 has a better corrosion inhibition effect on carbon steel.

[0065] like Figure 8 As shown, the impedance arc radius of the carbon steel sample electrodes in Examples 1, 2, and 3, compared to that of the comparative carbon steel sample electrode, indicates that Examples 1, 2, and 3 all have a certain inhibitory effect on the corrosion of carbon steel. Among them, the impedance arc radius of the carbon steel sample electrode in Example 2 is significantly larger than that in Examples 1 and 3, demonstrating that the modified amino acid assembly film in Example 2 has a better corrosion inhibitory effect on carbon steel.

[0066] 4. Electrochemical resistance polarization test:

[0067] The carbon steel samples (10mm × 10mm × 3mm) from Examples 1, 2, and 3 were used as working electrodes. A blank carbon steel sample without alanine-modified surface was used as a control electrode in the same manner. Electrochemical impedance spectroscopy (EIS) was performed using a three-electrode system, with a platinum electrode as the auxiliary electrode (CE) and a saturated calomel electrode (SCE) as the reference electrode (RE). The electrolyte was simulated atmospheric corrosion water (100 mg / L sulfate, 100 mg / L chloride, and 100 mg / L bicarbonate). A 5 mV sinusoidal signal was used for EIS, with a scan frequency from 100 kHz to 0.01 Hz. Polarization curves were scanned at 1 mV / s, and the polarization curve data were fitted using CView software on the CHI660D electrochemical workstation, based on Tafel polarization curve measurements.

[0068] The Tafel slopes of the cathode and anode are β and β, respectively. c and β a The corrosion potential and corrosion current density are E corr and i corrThe polarization curve is represented as a plot of current density, I, as a function of electrode potential, E. The corrosion current density is usually determined using the Tafel extrapolation method. The protection efficiency η i The calculation of the protection efficiency η is as follows:

[0069]

[0070] Table 2 Electrochemical polarization fitting parameters of carbon steel sample electrodes of Example 1, Example 2, Example 3 and Comparative Example in simulated atmospheric corrosion aqueous solution

[0071]

[0072] As shown in Table 2 and Figure 9 , the corrosion potential of the carbon steel sample electrodes of Example 1, 2 and 3 are all positively shifted and the corrosion current is reduced compared to the carbon steel sample electrode of the comparative example, indicating that the carbon steel is protected by Example 1, 2 and 3. Among them, the corrosion potential of the carbon steel sample electrode of Example 2 is positively shifted and the corrosion current is reduced compared to the carbon steel sample electrodes of Example 1 and Example 3, indicating that the modified amino acid assembly film of Example 2 has a more obvious inhibitory effect on the corrosion of the carbon steel sample electrode.

[0073] The above description of the examples is to facilitate the understanding and use of the invention by those of ordinary skill in the art. Those skilled in the art can obviously make various modifications to these examples and apply the general principles described herein to other examples without having to go through creative labor. Therefore, the present application is not limited to the above examples, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A modified amino acid corrosion inhibitor for carbon steel, characterized by, The method comprises the following steps: The amino acid is mixed with a base-binding agent and reacted to obtain an intermediate product; and the intermediate product is mixed with a synergist and reacted to obtain the modified amino acid corrosion inhibitor; The base-binding agent is phosphoric acid, and the synergist is a long-chain aliphatic amine with a carbon atom number greater than or equal to 8.

2. The modified amino acid inhibitor for carbon steel as claimed in claim 1 wherein, The amino acid is a non-polar amino acid.

3. The modified amino acid inhibitor for carbon steel as claimed in claim 2 wherein, The amino acid is alanine.

4. The modified amino acid inhibitor for carbon steel as claimed in claim 1 wherein, The mass percentage of each component of the modified amino acid corrosion inhibitor is as follows: Amino acid 60-70%; Base-binding agent 5-10%; Synergist 20-35%.

5. Use of the modified amino acid corrosion inhibitor of any one of claims 1 to 4 for corrosion protection of metals, characterized in that, The method comprises the following steps: The prepared modified amino acid corrosion inhibitor is placed at the bottom of a sealed container, and the carbon steel to be treated is placed above the modified amino acid corrosion inhibitor in the sealed container to obtain a modified amino acid corrosion film on the carbon steel after heating.

6. Use of modified amino acid inhibitor for carbon steel in metal corrosion protection according to claim 5, characterized in that, The heating temperature is 40-80 DEG C, and the time is 12-24 h.

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