A composite corrosion inhibitor suitable for marine alkaline environment storage tanks and its preparation method

Abstract

The present invention provides a composite corrosion inhibitor suitable for marine alkaline environment storage tanks and a preparation method thereof, and relates to the technical field of corrosion inhibition of metal materials. By weight, the composite corrosion inhibitor includes 40-70 parts of organic corrosion inhibitor, 10-20 parts of phytic acid, 20-30 parts of functional additives, 10-20 parts of surfactants and 5-10 parts of synergists. Through the synergistic compounding of organic corrosion inhibitors, phytic acid, functional additives, surfactants and synergists, a protective film is formed on the surface of the metal storage tank through chelation with the metal on the surface of the storage tank and electrostatic attraction, the force between the corrosion inhibitor and the metal is increased, and a uniform and dense protective film is formed on the surface of the metal storage tank, which improves the metal anticorrosion performance of the corrosion inhibitor. Thereby avoiding the erosion of the metal matrix by the corrosive medium.

Description

Technical Field

[0001] The invention belongs to the technical field of corrosion inhibition of metal materials, and in particular relates to a composite corrosion inhibitor suitable for marine alkaline environment storage tanks and a preparation method thereof. Background Art

[0002] Metal storage tanks have been widely used in offshore engineering. For example, copper-nickel alloy storage tanks produced by adding nickel to pure copper have better corrosion resistance and ductility. Most engineering facilities in the ocean use copper alloy as the main material. The salinity of seawater is generally between 3.2% and 3.75%, so the Cl content in seawater is - The high content makes seawater highly corrosive. In addition, seawater contains a large number of sulfate-reducing bacteria (SRB) and other corrosive microorganisms. 2- The reduction of H2S is very strong, and the surface structure of copper alloy components is destroyed by the reduction reaction. Sulfide is generated during the reduction reaction, which further corrodes the copper alloy components. Therefore, copper alloys are easily corroded and destroyed in the marine environment.

[0003] At present, the following measures can be taken to prevent seawater corrosion: develop and use new seawater corrosion-resistant materials with better performance, paint the surface, improve the corrosion resistance of the metal components used through surface treatment or surface modification, electrochemical protection, add corrosion inhibitors, and regularly conduct structural health monitoring and testing, safety evaluation and reliability analysis, and life assessment of marine engineering materials.

[0004] Adding corrosion inhibitors is an effective anti-corrosion method, but the existing corrosion inhibitors have little interaction with metals and are easily desorbed, resulting in poor anti-corrosion performance. Especially for high-salinity seawater, the anti-corrosion effect is relatively weak. Summary of the invention

[0005] In order to solve the above problems, a composite corrosion inhibitor suitable for marine alkaline environment storage tanks and a preparation method thereof are provided. The composite corrosion inhibitor of the present invention is obtained by synergistically compounding an organic corrosion inhibitor, phytic acid, a functional auxiliary agent, a surfactant and a synergist for the alkaline environment of seawater and the high salt content. The corrosion inhibitor forms a protective film on the surface of the metal storage tank through chelation with the metal on the surface of the storage tank and electrostatic attraction, thereby increasing the interaction between the corrosion inhibitor and the metal, forming a uniform and dense protective film on the surface of the metal storage tank, and improving the metal anti-corrosion performance of the corrosion inhibitor. Thus, the corrosion of the metal matrix by the corrosive medium is avoided.

[0006] On the one hand, the present invention provides a compound corrosion inhibitor suitable for marine alkaline environment storage tanks. Calculated by weight, the compound corrosion inhibitor includes 40-70 parts of organic corrosion inhibitor, 10-20 parts of phytic acid, 20-30 parts of functional additives, 10-20 parts of surfactants and 5-10 parts of synergist.

[0007] The composite corrosion inhibitor of the present invention is synergistically compounded by organic corrosion inhibitor, phytic acid, functional auxiliary agent, surfactant and synergist. Phytic acid is a biological organic acid that can react with organic corrosion inhibitor, can be attracted by the charge on the metal surface, and form a protective film on the surface of the metal storage tank to hinder or delay the relevant electrochemical reaction. In addition, a single organic corrosion inhibitor will have a protective film that is not uniform and dense enough, resulting in a poor anticorrosion effect. This application adds phytic acid, and phytic acid has a strong chelating ability with metal ions. During use, phytic acid, synergist, and surfactant can form chelates with metal ions dissolved in the anode, and are deposited on the surface of the metal storage tank by a chemical adsorption process, thereby inhibiting the dissolution of the anode. In addition, the group of the surfactant is adsorbed on the surface of the metal storage tank by electrostatic action, and the functional auxiliary agent can improve the heat and salt resistance of the corrosion inhibitor by compounding with other raw materials. The force between the corrosion inhibitor and the metal is improved, so that a uniform and dense protective film is formed on the surface of the metal storage tank, and the metal anticorrosion performance of the corrosion inhibitor is improved.

[0008] Optionally, the preparation method of the functional additive comprises the following steps: adding dopamine, 2-acrylamido-2-methylpropane sulfonic acid and sodium p-styrene sulfonate into deionized water, then adding a pH adjuster to adjust the pH to 7-8, then adding an initiator, reacting at a temperature of 40-60°C, and finally washing, filtering and drying to obtain the functional additive.

[0009] The mass ratio of dopamine, 2-acrylamide-2-methylpropane sulfonic acid and sodium p-styrene sulfonate is (3-8): (2-5): 1, and the initiator accounts for 0.05%-0.3% of the total mass of dopamine, 2-acrylamide-2-methylpropane sulfonic acid and sodium p-styrene sulfonate.

[0010] The present invention generates a functional additive by polymerizing dopamine, 2-acrylamido-2-methylpropane sulfonic acid, and sodium p-styrene sulfonate under the action of an initiator. The addition of the functional additive can further improve the heat resistance and salt corrosion resistance of the corrosion inhibitor. Furthermore, by adding dopamine, the functional additive contains a hydroxyl group, which has a strong electron-withdrawing ability and can chelate with the metal on the surface of the storage tank to isolate the corrosion of the corrosive medium from the metal matrix. On the other hand, by adding dopamine and polymerizing with other raw materials, a benzene ring is introduced, which can enhance the rigidity of the molecular chain; the introduction of the polar group sulfonic acid group in the functional additive improves the salt resistance, temperature resistance and thermal stability of the functional additive, and the synergistic effect with other raw materials can further increase the service life of the corrosion inhibitor and improve the corrosion resistance of the metal.

[0011] Optionally, the initiator is one or more of ammonium persulfate, sodium bisulfite, potassium persulfate, and sodium thiosulfate.

[0012] Optionally, the pH adjuster is one or more of sodium hydroxide, ammonia water or potassium hydroxide.

[0013] Optionally, the organic corrosion inhibitor is one or more of tallow amine, 2-mercaptobenzothiazole, benzotriazole, methylbenzotriazole, and cyclohexanehexol hexaphosphate.

[0014] Optionally, the surfactant is one or more of dodecyl dimethyl betaine, dodecyl dimethyl benzyl ammonium bromide or dodecyl-β-D-maltoside. In the present invention, the surfactant is an amphoteric surfactant, and the hydrophilic group of the amphoteric surfactant molecule can be adsorbed on the metal surface through electrostatic action, and the hydrophobic alkyl long chain of the amphoteric surfactant can prevent the solution from approaching the metal surface, thereby inhibiting the corrosion of chloride ions on the metal. At the same time, the introduction of the hydrophobic long chain can improve the temperature and salt resistance and thermal stability of the corrosion inhibitor.

[0015] Optionally, the synergist is sodium citrate or sodium gluconate. The synergist sodium citrate or sodium gluconate of the present invention contains a large amount of hydroxyl or carboxyl groups, has good metal ion complexing ability, and can further enhance the interaction between the corrosion inhibitor and the metal storage tank by synergistically compounding with other raw materials, thereby improving the corrosion resistance of the corrosion inhibitor.

[0016] Optionally, the mass ratio of organic corrosion inhibitor, phytic acid and functional additive is (2-3):1:1. Studies have found that although phytic acid can produce chelation with metal ions, adding too much phytic acid is not conducive to the adsorption of corrosion inhibitors on the surface of metal storage tanks.

[0017] Optional, marine alkaline environment with pH>7, Ca 2+ Not less than 500mg / L, Mg 2+Not less than 1500mg / L, Cl - Not less than 18000mg / L.

[0018] Another aspect of the present invention provides a method for preparing a composite corrosion inhibitor, the preparation method comprising the following steps:

[0019] (1) adding an organic corrosion inhibitor, phytic acid and a functional additive into deionized water in proportion, and reacting at a temperature of 60-70° C. to obtain a first solution;

[0020] (2) Then add the surfactant and the synergist in sequence and continue the reaction to obtain a composite corrosion inhibitor.

[0021] The present invention first mixes the organic corrosion inhibitor, phytic acid and the functional additive to prevent agglomeration caused by adding them all at once under the action of the surfactant, which is not conducive to the close action between the corrosion inhibitor and the metal.

[0022] Compared with the prior art, the present invention achieves at least one of the following beneficial effects:

[0023] (1) The present invention is a composite corrosion inhibitor suitable for marine alkaline environment storage tanks. The organic corrosion inhibitor, phytic acid, functional additives, surfactants and synergists are synergistically compounded to form a protective film on the surface of the metal storage tank through chelation with the metal on the surface of the storage tank and electrostatic attraction, thereby increasing the interaction between the corrosion inhibitor and the metal, forming a uniform and dense protective film on the surface of the metal storage tank, and improving the metal anti-corrosion performance of the corrosion inhibitor. This avoids the erosion of the metal substrate by the corrosive medium.

[0024] (2) In the present invention, dopamine, 2-acrylamido-2-methylpropane sulfonic acid and sodium p-styrene sulfonate are polymerized under the action of an initiator to generate a functional additive. The addition of the functional additive can further improve the temperature resistance and salt corrosion resistance of the corrosion inhibitor.

[0025] (3) The surfactant in the present invention is an amphoteric surfactant. The hydrophilic groups of the amphoteric surfactant molecules can be adsorbed on the metal surface through electrostatic action. The hydrophobic alkyl long chains of the amphoteric surfactant can prevent the solution from approaching the metal surface, thereby inhibiting the corrosion of chloride ions on the metal. At the same time, the introduction of the hydrophobic long chain can improve the temperature and salt resistance and thermal stability of the corrosion inhibitor. DETAILED DESCRIPTION

[0026] In order to more clearly illustrate the overall concept of the present invention, a detailed description is given below by way of examples.

[0027] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0028] Example 1

[0029] The compound corrosion inhibitor is suitable for marine alkaline environment storage tanks. Calculated by weight, the compound corrosion inhibitor includes 40 parts of organic corrosion inhibitor tallow amine, 10 parts of phytic acid, 20 parts of functional additive dopamine, 10 parts of dodecyl dimethyl betaine and 5 parts of sodium citrate.

[0030] The preparation method of the composite corrosion inhibitor comprises the following steps:

[0031] (1) adding tallow amine, phytic acid and dopamine to deionized water in proportion, and reacting at a temperature of 60° C. to obtain a first solution;

[0032] (2) Add dodecyl dimethyl betaine and sodium citrate in sequence and continue the reaction to obtain a composite corrosion inhibitor.

[0033] Example 2

[0034] The compound corrosion inhibitor is suitable for marine alkaline environment storage tanks. Calculated by weight, the compound corrosion inhibitor includes 70 parts of organic corrosion inhibitor 2-mercaptobenzothiazole, 20 parts of phytic acid, 30 parts of functional additive 2-acrylamido-2-methylpropanesulfonic acid, 10 parts of dodecyldimethylbenzyl ammonium bromide and 5 parts of sodium gluconate.

[0035] The preparation method of the composite corrosion inhibitor comprises the following steps:

[0036] (1) adding 2-mercaptobenzothiazole, phytic acid and 2-acrylamido-2-methylpropanesulfonic acid into deionized water in proportion, and reacting at a temperature of 70° C. to obtain a first solution;

[0037] (2) Add dodecyl dimethyl benzyl ammonium bromide and sodium gluconate in sequence, and continue the reaction to obtain a composite corrosion inhibitor.

[0038] Example 3

[0039] The compound corrosion inhibitor is suitable for marine alkaline environment storage tanks. Calculated by weight, the compound corrosion inhibitor includes 60 parts of organic corrosion inhibitor benzotriazole, 20 parts of phytic acid, 20 parts of functional additive sodium p-styrene sulfonate, 15 parts of dodecyl-β-D-maltoside and 8 parts of sodium gluconate.

[0040] The preparation method of the composite corrosion inhibitor comprises the following steps:

[0041] (1) adding benzotriazole, phytic acid and sodium p-styrene sulfonate into deionized water in proportion, and reacting at a temperature of 65° C. to obtain a first solution;

[0042] (2) Then, dodecyl-β-D-maltoside and sodium gluconate are added in sequence, and the reaction is continued to obtain a composite corrosion inhibitor.

[0043] Example 4

[0044] The compound corrosion inhibitor is suitable for storage tanks in marine alkaline environments. Calculated by weight, the compound corrosion inhibitor includes 60 parts of organic corrosion inhibitor cyclohexanehexol hexaphosphate, 20 parts of phytic acid, 20 parts of functional additives, 15 parts of dodecyl-β-D-maltoside and 8 parts of sodium gluconate.

[0045] The preparation method of the functional additive comprises the following steps: adding dopamine, 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate into deionized water in a mass ratio of 3:2:1, then adding sodium hydroxide to adjust the pH to 7, then adding 0.05% of an initiator sodium thiosulfate, reacting at a temperature of 40°C, and finally washing, filtering and drying to obtain the functional additive;

[0046] The preparation method of the composite corrosion inhibitor comprises the following steps:

[0047] (1) adding cyclohexanehexol hexaphosphate, phytic acid and a functional additive into deionized water in proportion, and reacting at a temperature of 65° C. to obtain a first solution;

[0048] (2) Then, dodecyl-β-D-maltoside and sodium gluconate are added in sequence, and the reaction is continued to obtain a composite corrosion inhibitor.

[0049] Example 5

[0050] The compound corrosion inhibitor is suitable for marine alkaline environment storage tanks. Calculated by weight, the compound corrosion inhibitor includes 40 parts of organic corrosion inhibitor methyl benzotriazole, 20 parts of phytic acid, 20 parts of functional additives, 15 parts of dodecyl-β-D-maltoside and 8 parts of sodium gluconate.

[0051] The preparation method of the functional additive comprises the following steps: adding dopamine, 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate into deionized water in a mass ratio of 8:2:1, then adding ammonia water to adjust the pH to 8, then adding 0.1% of initiator potassium persulfate, reacting at a temperature of 60°C, and finally washing, filtering and drying to obtain the functional additive;

[0052] The preparation method of the composite corrosion inhibitor comprises the following steps:

[0053] (1) adding methylbenzotriazole, phytic acid and functional additives into deionized water in proportion, and reacting at a temperature of 65° C. to obtain a first solution;

[0054] (2) Then, dodecyl-β-D-maltoside and sodium gluconate are added in sequence, and the reaction is continued to obtain a composite corrosion inhibitor.

[0055] Example 6

[0056] Based on Example 5, the main difference is that the preparation method of the functional additive includes the following steps: dopamine, 2-acrylamido-2-methylpropane sulfonic acid, and sodium p-styrene sulfonate are added to deionized water in a mass ratio of 5:3:1, and then ammonia water is added to adjust the pH to 8, and then 0.1% potassium persulfate as an initiator is added, reacting at a temperature of 60°C, and finally washing, filtering, and drying to obtain the functional additive.

[0057] Example 7

[0058] Based on Example 5, the main difference is that the surfactant is sodium dodecylbenzene sulfonate.

[0059] Comparative Example 1

[0060] Based on Example 1, the main difference is that the amount of phytic acid added is 50 parts.

[0061] Comparative Example 2

[0062] The main difference from Example 1 is that no functional additive is added.

[0063] Comparative Example 3

[0064] The main difference between Example 1 and Example 1 is that no phytic acid is added.

[0065] Experimental example

[0066] According to the national standard GB10124-88, the copper alloy was processed into several samples of 50mm×20mm×5mm, and the samples were polished with sandpaper, cleaned with anhydrous ethanol, and weighed after drying. The samples were sprayed with the corrosion inhibitors of Examples 1-7 and Comparative Examples 1-3, dried, and placed at pH 8, Ca 2+ Not less than 500mg / L, Mg 2+ Not less than 1500mg / L, Cl - Immerse in seawater with a concentration of not less than 18000 mg / L, and set a blank control, that is, immerse directly without spraying corrosion inhibitor, the corrosion time is 10 cycles, and the immersion temperatures are set to 25°C and 70°C respectively.

[0067] According to the cleaning method of GB / T16545-1996, after the copper alloy was subjected to 10 dry-wet cycle corrosion tests, it was immersed in the cleaning solution for ten minutes at 298K, washed twice with distilled water, ultrasonicated in anhydrous ethanol for 10 minutes, dehydrated, and placed in a drying oven to dry for 24 hours before weighing. The cleaning solution is made of 500ml concentrated hydrochloric acid and 3.5g hexamethylenetetramine, and distilled water is added to make a 1000ml solution. Each solution was measured three times in parallel to obtain the average value. The corrosion inhibition rate η% of the weight loss experiment is obtained by the following formula:

[0068] ;

[0069] ;

[0070] Where v is the corrosion rate, mg·(cm 2 d) -1 , v0 is the copper alloy corrosion rate of the blank control test group, mg·(cm 2 d) -1 ;v i is the corrosion rate of the copper alloy in the example or comparative test group, mg·(cm 2 d) -1 ; ΔW is the weight difference before and after corrosion, mg; S is the surface area of ​​the sample, cm 2 ; t is the corrosion time, d. The test results are shown in Table 1.

[0071] Table 1

[0072]

[0073] Referring to Table 1, it can be seen that at room temperature, the corrosion rate of the corrosion inhibitor prepared in this application is no higher than 0.1 mg·(cm 2 d) -1 , the corrosion inhibition rate is not less than 90%. At 70°C, the corrosion rate of the corrosion inhibitor prepared by the present application is not higher than 0.2mg·(cm 2 d) -1 , the corrosion inhibition rate is not less than 80%. The corrosion inhibitor prepared in the present application has good metal corrosion inhibition performance and temperature and salt resistance.

[0074] In addition, the adhesion of the composite corrosion inhibitors of Examples 1-7 of the present application was tested according to the GB / T 1720-1979 standard. The test results showed that the adhesion was greater than 10 MPa and the impact resistance was greater than 50 cm. The corrosion inhibitor prepared in the present application has good strength and a strong interaction with metals.

[0075] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A composite corrosion inhibitor suitable for marine alkaline environment storage tanks, characterized in that: By weight, the compound corrosion inhibitor includes 40-70 parts of organic corrosion inhibitor, 10-20 parts of phytic acid, 20-30 parts of functional additive, 10-20 parts of surfactant and 5-10 parts of synergist; The preparation method of the functional additive comprises the following steps: Dopamine, 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate are added to deionized water, and then a pH adjuster is added to adjust the pH to 7-8, and then an initiator is added to react at a temperature of 40-60° C., and finally washed, filtered and dried to obtain a functional additive; The mass ratio of dopamine, 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate is (3-8): (2-5): 1, the initiator accounts for 0.05%-0.3% of the total mass of dopamine, 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate; The organic corrosion inhibitor is one or more of tallow amine, 2-mercaptobenzothiazole, benzotriazole, methylbenzotriazole, and cyclohexanehexol hexaphosphate; The surfactant is one or more of dodecyl dimethyl betaine, dodecyl dimethyl benzyl ammonium bromide or dodecyl-β-D-maltoside; The marine alkaline environment has a pH>7, Ca 2+ Not less than 500mg / L, Mg 2+ Not less than 1500mg / L.

2. The composite corrosion inhibitor according to claim 1, characterized in that: The initiator is one or more of ammonium persulfate, sodium bisulfite, potassium persulfate, and sodium thiosulfate.

3. The composite corrosion inhibitor according to claim 1, characterized in that: The pH regulator is one or more of sodium hydroxide, ammonia water or potassium hydroxide.

4. The composite corrosion inhibitor according to claim 1, characterized in that: The enhancer is sodium citrate or sodium gluconate.

5. The composite corrosion inhibitor according to claim 1, characterized in that: The mass ratio of organic corrosion inhibitor, phytic acid and functional additive is (2-3):1:

1.

6. A method for preparing the composite corrosion inhibitor according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) adding an organic corrosion inhibitor, phytic acid and a functional additive into deionized water in proportion, and reacting at a temperature of 60-70° C. to obtain a first solution; (2) Then add the surfactant and the synergist in sequence and continue the reaction to obtain a composite corrosion inhibitor.

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