2-phosphate-1, 2, 4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor as well as preparation method and application of 2-phosphate-1, 2, 4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor

Abstract

The invention discloses a 2-phosphate group-1, 2, 4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor as well as a preparation method and application of the 2-phosphate group-1, 2, 4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor. Each liter of the corrosion inhibitor comprises 50 to 200 mg / L of 2-phosphoric acid-1, 2, 4-tricarboxylic acid butane, 50 to 250 mg / L of sodium fluoride and the balance of water; according to the 2-phosphate group-1, 2, 4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor disclosed by the invention, the corrosion inhibition synergistic effect is achieved by compounding the 2-phosphate group-1, 2, 4-tricarboxylic acid butane and the sodium fluoride; the corrosion inhibitor has the characteristics of no toxicity and environmental protection, is environment-friendly, and meets the requirements of sustainable development; in addition, the preparation process is simple and convenient, the synthesis process is controllable, the production cost is low, and the method is suitable for industrial large-scale production; after being treated by the corrosion inhibitor, a compact and uniform protective film is formed on the surface of the stainless steel composite plate, so that the corrosion of a corrosive medium is effectively blocked, and the corrosion resistance of a material is improved.

Description

Technical Field

[0001] The present invention relates to a compound corrosion inhibitor, in particular to a 2-phosphono-1,2,4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor, and also relates to a preparation method and an application of the above compound corrosion inhibitor. Background Art

[0002] In an acidic environment, using a corrosion inhibitor is one of the most effective measures to protect the surface of metal specimens from corrosion. A corrosion inhibitor is a chemical substance that can effectively slow down or prevent the corrosion of metal materials in a specific medium, or is composed of a compound of multiple chemical components. Its mechanism of action mainly depends on forming a protective film on the metal surface, thereby reducing the direct contact between the metal and the corrosive medium. Inhibitors are widely used in the anti-corrosion treatment of industrial equipment, pipelines and metal components to reduce the corrosion rate and extend the service life. Especially in an acidic environment, a variety of organic inhibitors can effectively reduce the corrosion degree of stainless steel composite plates. Most highly efficient organic inhibitor molecules contain heteroatoms such as O, N, S, etc. and have multiple active functional groups, and these active functional groups can have strong physical or chemical adsorption with the metal surface, and then form a stable protective layer to reduce metal dissolution.

[0003] In recent years, polymer corrosion inhibitors have received extensive attention due to their excellent anti-corrosion performance. Compared with small molecule organic corrosion inhibitors, polymers have longer molecular chain structures and more adsorption sites, enabling them to form a more uniform and wider coverage protective film on the metal surface. This adsorption film can not only effectively block the erosion of corrosive anions on the metal, but also reduce water penetration through hydrophobic action, thereby enhancing the anti-corrosion effect.

[0004] Currently widely used organic phosphonic acid corrosion inhibitors (such as HEDP, ATMP, DTPMP, etc.) play a certain protective role in metal corrosion inhibition, but there are still the following problems: the corrosion inhibition efficiency decreases in high temperature, high Cl - concentration or strong oxidation environment, and it is difficult to provide long-term protection; the synthesis requires multiple reaction steps, involving processes such as phosphoric acid esterification, and the production cost is relatively high; traditional organic phosphonic acid corrosion inhibitors are prone to cause eutrophication problems in water bodies, which does not conform to the development trend of green chemistry, and there is an urgent need to develop new corrosion inhibitors. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a 2-phosphono-1,2,4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor, and also provide a preparation method of the above compound corrosion inhibitor and its application in the anti-corrosion of metal materials.

[0006] Technical solution: The present invention discloses a compound corrosion inhibitor of 2-phosphono-1,2,4-tricarboxybutane-sodium fluoride. The compound corrosion inhibitor comprises 2-phosphono-1,2,4-tricarboxybutane and sodium fluoride. Each liter of the corrosion inhibitor comprises 50-200 mg of 2-phosphono-1,2,4-tricarboxybutane, 50-250 mg of sodium fluoride, and the balance is water.

[0007] Among them, preferably, each liter of the corrosion inhibitor comprises 100-200 mg of 2-phosphono-1,2,4-tricarboxybutane and 50-100 mg of sodium fluoride, and the balance is water. More preferably, each liter of the corrosion inhibitor comprises 100 mg of 2-phosphono-1,2,4-tricarboxybutane and 100 mg of sodium fluoride, and the balance is water.

[0008] Among them, the pH value of the corrosion inhibitor is 7-8.

[0009] Among them, the corrosion inhibitor is of analytical purity, and the water is deionized water.

[0010] The preparation method of the above compound corrosion inhibitor comprises the following steps:

[0011] (1) Take water accounting for 15-45% of the volume of the target corrosion inhibitor to be prepared;

[0012] (2) Take 2-phosphono-1,2,4-tricarboxybutane and sodium fluoride, and dissolve them respectively with water to obtain a 2-phosphono-1,2,4-tricarboxybutane corrosion inhibitor solution and a sodium fluoride corrosion inhibitor solution;

[0013] (3) Mix the above 2-phosphono-1,2,4-tricarboxybutane corrosion inhibitor solution and sodium fluoride corrosion inhibitor solution, stir until completely uniform, add the remaining aqueous solution, and stir evenly to obtain the compound corrosion inhibitor of 2-phosphono-1,2,4-tricarboxybutane-sodium fluoride.

[0014] Among them, in step (2), the dosage of the water is 50-150 ml; the volumes of the 2-phosphono-1,2,4-tricarboxybutane corrosion inhibitor solution and the sodium fluoride corrosion inhibitor solution are 50-150 ml, and the volume ratio is 1:1:1.

[0015] The present invention also discloses the application of the above compound corrosion inhibitor of 2-phosphono-1,2,4-tricarboxybutane-sodium fluoride in the anti-corrosion of metal materials.

[0016] Among them, the application is the anti-corrosion of stainless steel pipes in petrochemical pipelines.

[0017] Among them, the concentration ratio of the acidic corrosion solution in the pipeline steel to the concentration of the corrosion inhibitor is 1:1.5-2, preferably 1:2.

[0018] Among them, the application specifically is to form a protective film on the surface of the stainless steel composite plate by using a compound corrosion inhibitor to hinder the corrosion in an acidic environment: Prepare a 2-phosphono-1,2,4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor according to the concentration of the corrosion liquid in petrochemical pipelines. Use a pipeline corrosion inhibitor plug to cover the surface of the stainless steel composite plate with the 2-phosphono-1,2,4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor under the push of gas. After drying, the acidic corrosion liquid can be introduced.

[0019] During the application process, use on-site exploration instruments to monitor the corrosiveness of the corrosion liquid after corrosion inhibition and determine the corrosion inhibition effect of the corrosion inhibitor. After the corrosion inhibition effect decreases, it can be repeatedly coated to restore or increase the corrosion inhibition effect.

[0020] Principle of the invention: The 2-phosphono-1,2,4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor of the present invention is obtained by compounding PBTCA and sodium fluoride. Through the combination of 2-phosphono-1,2,4-tricarboxylic acid butane and F - adsorption occurs on the metal surface, and halide ions increase the adsorption ability of organic cations by forming a bridge between the negatively charged metal surface and the inhibitor cations.

[0021] 2-phosphono-1,2,4-tricarboxylic acid butane, its structure contains a phosphono group (-PO 4 H 2 ) and multiple carboxyl groups (-COOH). These polar groups can interact with the metal surface to play a corrosion inhibition role. Since the phosphono group and carboxyl group can dissociate to form negative ions (PO 4 2- , COO - ), they can be directly adsorbed on the metal surface through electrostatic interaction or coordination bond to form a protective film. This adsorption reduces the activity of the metal surface, thereby reducing the attack of corrosion media (such as Cl - , O 2 , H + ) on the metal.

[0022] Adding sodium fluoride to the 2-phosphono-1,2,4-tricarboxylic acid butane solution, F - in sodium fluoride can form a "bridge" with this organophosphonic acid carboxylic compound on the negatively charged metal surface to enhance its adsorption ability. Specifically, F - may connect the metal surface with the cationic part of the corrosion inhibitor through hydrogen bonding or electrostatic interaction to improve its stability. This not only increases the coverage rate of the organic corrosion inhibitor but also enhances its adhesion on the metal surface, making the protective film more dense and uniform. Since the phosphono group and carboxyl group can form strong coordination chemical adsorption with metals (such as Fe, Al, Cu, etc.), this adsorption layer can further react with metal ions in the solution (such as Fe3+ , Fe 2+ ) reacts to form insoluble complexes or precipitates, improving the corrosion inhibition effect. This protective layer can effectively prevent the penetration of corrosive media (such as Cl - , H 2 O, O 2 ), reducing the corrosion rate of the metal. 2-phosphono-1,2,4-tricarboxylic acid butane itself has good adsorption ability, and the addition of F - enhances its adsorption ability through ionic bridging, thus forming a denser protective layer on the metal surface. This synergistic effect significantly improves the performance of the corrosion inhibitor, enabling it to more effectively inhibit metal corrosion.

[0023] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: (1) The 2-phosphono-1,2,4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor of the present invention effectively improves the corrosion inhibition of steel, and the highest corrosion inhibition efficiency can reach 91.29%. For the existing organic phosphonic acid compound corrosion inhibitors, the corrosion inhibition efficiency is usually between 70% and 85%. Compared with the common compound system with a corrosion inhibition efficiency of 75%, the corrosion inhibition efficiency of the present invention is increased by about 1.2 times; (2) The corrosion inhibitor of the present invention is non-toxic and environmentally friendly, friendly to the environment, meets the requirements of sustainable development, has a simple preparation process, a controllable synthesis process, and a low production cost, and is suitable for large-scale industrial production. Description of the Drawings

[0024] Figure 1 is the polarization curve of 316L / Q370qE stainless steel composite plate in the compound corrosion inhibitor of the present invention;

[0025] Figure 2 is the polarization curve of 316L / Q370qE stainless steel composite plate in 2-phosphono-1,2,4-tricarboxylic acid butane corrosion inhibitor with different concentrations;

[0026] Figure 3 is the polarization curve of 316L / Q370qE stainless steel composite plate in sodium fluoride corrosion inhibitor with different concentrations;

[0027] Figure 4 is the curve graph of c / θ vs. c of 2-phosphono-1,2,4-tricarboxylic acid butane-sodium fluoride compound corrosion inhibitor with different concentrations. Detailed Embodiments

[0028] The technical solutions of the present invention will be further described below in conjunction with the embodiments. The test materials used in the embodiments can be obtained through conventional channels.

[0029] Example 1

[0030] The 2-phosphono-1,2,4-tricarboxybutane-sodium fluoride compound corrosion inhibitor of the present invention comprises raw materials of the following components: 2-phosphono-1,2,4-tricarboxybutane 1, sodium fluoride and water.

[0031] (1) Take water accounting for 15% of the volume of the target corrosion inhibitor to be prepared;

[0032] (2) Weigh analytical pure 2-phosphono-1,2,4-tricarboxybutane, add water, and respectively prepare 2-phosphono-1,2,4-tricarboxybutane corrosion inhibitor solutions with volumes of 50 ml and concentrations of 50, 100, 150, and 200 mg / L;

[0033] Weigh analytical pure sodium fluoride, add water, and respectively prepare sodium fluoride corrosion inhibitor solutions with volumes of 50 ml and concentrations of 50, 100, 150, 200, and 250 mg / L;

[0034] (3) Mix the above-mentioned 2-phosphono-1,2,4-tricarboxybutane corrosion inhibitor solution and sodium fluoride corrosion inhibitor solution, make it evenly mixed and then make the volume constant to 1 L, conduct compounding research on 2-phosphono-1,2,4-tricarboxybutane h and sodium fluoride to study their synergistic effect, and verify the corrosion inhibition effect of the prepared 2-phosphono-1,2,4-tricarboxybutane-sodium fluoride compound corrosion inhibitor of the present invention.

[0035] On the basis of the corrosion inhibition performance of 316L / Q370qE stainless steel composite plates by using the two corrosion inhibitors of 2-phosphono-1,2,4-tricarboxybutane and sodium fluoride alone, determine an appropriate concentration range according to the relationship between the corrosion inhibition efficiency and concentration of the single corrosion inhibitor. Take the concentration as the level and the type of corrosion inhibitor as the factor, and conduct experiments. The experiments are shown in Table 1:

[0036] Table 1. Factor level table of the compound corrosion inhibitor of the present invention

[0037]

[0038] Number each experiment in the experimental table of Table 1, and calculate the corrosion inhibition rate as shown in Table 2 according to the polarization curves of the corresponding specimens.

[0039] Table 2. Analysis of experimental results of the compound corrosion inhibitor of the present invention

[0040]

[0041]

[0042] As can be seen from Table 2, the optimal concentration ratio of the compound of 2-phosphono-1,2,4-tricarboxybutane and sodium fluoride is 100 mg / L of 2-phosphono-1,2,4-tricarboxybutane and 100 mg / L of sodium fluoride.

[0043] According to the best compounding combination obtained from experiments, the results of parallel experiments are as follows: Figure 1 As shown in . For the compound corrosion inhibitor with the concentration of 2-phosphono-1,2,4-tricarboxylic acid butane being 100 mg / L and the concentration of sodium fluoride being 100 mg / L, the corrosion inhibition rate for the 316L / Q370qE stainless steel composite plate in HCl medium can reach 91.29%.

[0044] For the steel corrosion inhibitor in Comparative Example 1, the components and contents are: 2-phosphono-1,2,4-tricarboxylic acid butane at 50, 100, 150, 200 mg / L, and the rest is water.

[0045] The preparation method of the above corrosion inhibitor, taking the preparation of 100 ml of corrosion inhibitor as an example, specifically includes the following steps:

[0046] (1) Take 4 beakers with a capacity of 100 ml, and add 50 ml of HCl solution prepared to 0.5 mol / L;

[0047] (2) Add 50 ml of the prepared 2-phosphono-1,2,4-tricarboxylic acid butane solution at 50, 100, 150, 200 mg / L to the solution obtained in step (1) respectively, stir evenly until completely dissolved to obtain a mixed solution.

[0048] Cut the steel into specimens of 10 mm×10 mm×3 mm for the working electrode (WE). The WE is embedded in epoxy resin with a geometric surface area of 1 cm 2 and exposed to the electrolyte. Before all measurements, grind the samples with emery paper of 400 to 2000 grit respectively, perform ultrasonic degreasing in ethanol and acetone, and dry at room temperature.

[0049] Use a traditional three-electrode cell assembly, where the counter electrode is made of platinum foil and the reference electrode is a saturated calomel electrode (SCE). The polarization curve is obtained at a scanning rate of 0.5 mV / s and starts from a potential of -350 mV to +350 mV after the working electrode reaches a steady state (OCP fluctuation less than ±5 mV).

[0050] As shown in Figure 2 are the polarization curves of the 316L / Q370qE stainless steel composite plate in corrosion inhibitors with different concentrations of 2-phosphono-1,2,4-tricarboxylic acid butane. It can be seen from the figure that the addition of 2-phosphono-1,2,4-tricarboxylic acid butane has an inhibitory effect on the corrosion of the 316L / Q370qE stainless steel composite plate. With the increase of the concentration of 2-phosphono-1,2,4-tricarboxylic acid butane, the inhibitory effect on the anodic process is enhanced. When the concentration reaches 200 mg / L, the inhibitory effect weakens instead. The fitting data is shown in Table 3.

[0051] Table 3. Polarization Curve Parameters of 316L / Q370qE Stainless Steel Clad Plate in 2-phosphono-1, 2, 4-tricarboxybutane Inhibitor with Different Concentrations

[0052]

[0053] When the concentration of 2-phosphono-1, 2, 4-tricarboxybutane is 100 mg / L, the self-corrosion current is the smallest. However, with the increase of concentration, the self-corrosion current also increases. After adding the inhibitor, the self-corrosion potential shifts positively, indicating that the inhibitory effect of 2-phosphono-1, 2, 4-tricarboxybutane on the anodic reaction of the corrosion process is significantly greater than that of the cathode. Its reaction mechanism may be that a protective film is formed on the metal surface to play an inhibitory role.

[0054] Comparative Example 2

[0055] For the steel corrosion inhibitor of Comparative Example 2, the components and contents are: sodium fluoride 50, 100, 150, 200, 250 mg / L, and the rest is water.

[0056] The preparation method of the above corrosion inhibitor, taking the preparation of 100 ml of corrosion inhibitor as an example, specifically includes the following steps:

[0057] (1) Take 4 beakers with a capacity of 100 ml, and add 50 ml of HCl solution configured to 0.5 mol / L;

[0058] (2) Add 50 ml of prepared 2-sodium fluoride solutions with concentrations of 50, 100, 150, 200, 250 mg / L to the solution obtained in step (1) respectively, stir evenly until completely dissolved to obtain a mixed solution.

[0059] Cut the steel into specimens of 10 mm×10 mm×3 mm for the working electrode (WE). The WE is embedded in epoxy resin with a geometric surface area of 1 cm 2 and exposed to the electrolyte. Before all measurements, the samples are ground with emery paper with particle sizes from 400 to 2000, ultrasonically degreased in ethanol and acetone, and dried at room temperature.

[0060] Use a traditional three-electrode cell assembly, where the counter electrode is made of platinum foil and the reference electrode is a saturated calomel electrode (SCE). The polarization curve is obtained at a scanning rate of 0.5 mV / s and starts from a potential of -350 mV to +350 mV after the working electrode reaches a stable state (OCP fluctuation less than ±5 mV).

[0061] As Figure 3 shown, the polarization curves of 316L / Q370qE stainless steel clad plate in sodium fluoride inhibitors with different concentrations are presented. Through Tafel fitting, the obtained fitting parameters are shown in Table 4:

[0062] Table 4. Polarization curve parameters of 316L / Q370qE stainless steel clad plate in sodium fluoride inhibitors with different concentrations

[0063]

[0064] From the data in the table, it can be seen that when the concentration of sodium fluoride is 100 mg / L, the self-corrosion current is the smallest, indicating that sodium fluoride has the best anti-corrosion effect. The principle is that sodium fluoride contains halogen elements and is a synergist, which can reduce the adsorption of Cl - on the steel surface, thus achieving the corrosion inhibition effect.

[0065] Comparing Figure 1 and Figure 4 experimental data, when 1,2,4-butanetricarboxylic acid-1-phosphonic acid and sodium fluoride exist alone, the corrosion inhibition efficiencies for steel are 75.62% and 62.75% respectively. When the two inhibitors are compounded at the optimal concentration, the corrosion inhibition efficiency can reach 91.29%, which is 20 - 30% higher than that of a single solution, bringing a significant improvement in the effect.

[0066] In the PBTCA (50 - 200 mg / L) + NaF (50 - 250 mg / L) compound system of the present invention, the best corrosion inhibition effect is achieved. When PBTCA < 50 mg or NaF < 50 mg, the corrosion inhibition efficiency drops significantly, and it is unable to effectively form a protective film or the protective film is not dense enough, and the synergistic effect is insufficient; when PBTCA > 200 mg or NaF > 250 mg, the corrosion inhibition efficiency no longer increases. Excessive PBTCA easily leads to adsorption saturation on the metal surface, and problems such as precipitation and imbalance will also occur, resulting in a decline in corrosion inhibition performance.

[0067] Therefore, the 1,2,4-butanetricarboxylic acid-1-phosphonic acid-sodium fluoride compound corrosion inhibitor of the present invention achieves a corrosion inhibition synergistic effect, effectively improves the corrosion inhibition of steel, and the highest corrosion inhibition efficiency can reach 91.29%. Compared with the compound systems of common organophosphonic acid compound corrosion inhibitors, the corrosion inhibition efficiency of the present invention is increased by about 1.2 times. It has the characteristics of being non-toxic and environmentally friendly, is friendly to the environment, and meets the requirements of sustainable development. In addition, the preparation process of the present invention is simple, the synthesis process is controllable, the production cost is low, and it is suitable for large-scale industrial production. After being treated with this corrosion inhibitor, a dense and uniform protective film is formed on the surface of the stainless steel clad plate, effectively blocking the erosion of corrosive media and improving the corrosion resistance of the material.

Claims

1. A 2-phosphoryl-1,2,4-tricarboxylic acid butane-sodium fluoride composite corrosion inhibitor, characterized in that: The compound corrosion inhibitor comprises 2-phosphate-1,2,4-tricarboxylic acid butane and sodium fluoride. The corrosion inhibitor comprises 50-200 mg of 2-phosphate-1,2,4-tricarboxylic acid butane and 50-250 mg of sodium fluoride per liter, and the balance is water.

2. The composite corrosion inhibitor according to claim 1, characterized in that The corrosion inhibitor comprises 100-200 mg of 2-phospho-1,2,4-tricarboxylic acid butane, 50-100 mg of sodium fluoride, and the balance of water per liter.

3. The composite corrosion inhibitor according to claim 1, characterized in that The pH value of the corrosion inhibitor is 7-8.

4. A method for preparing the composite corrosion inhibitor according to claim 1, characterized in that: The following steps are involved: (1) Take 15-45% of the volume of water to prepare the target corrosion inhibitor; (2) taking 2-phosphate-1,2,4-tricarboxylic acid butane and sodium fluoride, and dissolving them in water to obtain 2-phosphate-1,2,4-tricarboxylic acid butane corrosion inhibitor and sodium fluoride corrosion inhibitor; (3) The above 2-phosphate-1,2,4-tricarboxylic acid butane corrosion inhibitor and sodium fluoride corrosion inhibitor are mixed, stirred until completely uniform, and the remaining aqueous solution is added and stirred uniformly to obtain a 2-phosphate-1,2,4-tricarboxylic acid butane-sodium fluoride composite corrosion inhibitor.

5. Use of the 2-phosphoryl-1,2,4-tricarboxylic acid butane-sodium fluoride composite corrosion inhibitor according to claim 1 in the aspect of corrosion resistance of metal materials.

6. The use according to claim 5, characterized in that: The application is the corrosion protection of stainless steel pipes in petrochemical pipelines.

7. The use according to claim 6, characterized in that: The ratio of the concentration of acidic corrosive liquid to the concentration of corrosion inhibitor in pipeline steel is 1:1.5~2.

8. The use according to claim 6, characterized in that: The application is specifically to form a protective film on the surface of the stainless steel composite plate using a compound corrosion inhibitor to hinder corrosion in an acidic environment.

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