CN114164430A - Metal corrosion inhibitor and preparation method thereof - Google Patents
Metal corrosion inhibitor and preparation method thereof Download PDFInfo
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
- C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
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Abstract
The application discloses a metal corrosion inhibitor and a preparation method thereof, wherein the metal corrosion inhibitor comprises the following components: 10-30 parts by weight of thiophene carboxylic acid substance, 50-200 parts by weight of first solvent, 10-30 parts by weight of additive, 10-20 parts by weight of dioxane, 5-15 parts by weight of methionine, 20-120 parts by weight of alkaline reagent, 10-20 parts by weight of second solvent and 10-30 parts by weight of acidic reagent, wherein the first solvent is dichloromethane, trichloromethane or toluene, the second solvent is water or dioxane, the additive is oxalyl chloride or thionyl chloride, and when the additive is oxalyl chloride, the metal corrosion inhibitor further comprises: 0.1-0.5 part by weight of catalyst, the metal corrosion inhibitor of the application uses thiophene carboxylic acid substance and methionine as raw materials, and the raw materials have wide sources, low cost, no toxicity, no harm and environmental protection.
Description
Technical Field
The invention relates to the technical field of metal materials, in particular to a metal corrosion inhibitor and a preparation method thereof.
Background
However, due to the nature of the metal, the metal is exposed to the natural environment and is easy to generate chemical reaction or electrochemical reaction so as to be corroded, so that the performance of the metal material is damaged, and resource loss and potential safety hazard are caused.
The metal corrosion is prevented by the metal corrosion inhibitor, which is one of the best corrosion prevention methods in the current industrial application, however, most of the existing metal corrosion inhibitors have high toxicity, easily cause heavy metal pollution to the environment, and have the defect of high production cost, so that the metal corrosion inhibitors still have certain limitations in the aspects of application and popularization.
Disclosure of Invention
Based on the above, the main purpose of the present invention is to provide a low-cost and environment-friendly metal corrosion inhibitor and a preparation method thereof.
In order to achieve the above object, the present invention provides a metal corrosion inhibitor, comprising:
thiophene carboxylic acid species: 10-30 parts by weight;
a first solvent: 50-200 parts by weight;
addition of: 10-30 parts by weight;
dioxane: 10-20 parts by weight;
methionine: 5-15 parts by weight;
alkaline reagent: 20-120 parts by weight;
a second solvent: 10-20 parts by weight;
acid reagent: 10-30 parts by weight;
wherein, the first solvent is dichloromethane, trichloromethane or toluene, the second solvent is water or dioxane, the additive is oxalyl chloride or thionyl chloride, and when the additive is oxalyl chloride, the metal corrosion inhibitor further comprises: 0.1 to 0.5 part by weight of a catalyst.
Preferably, the thiophene carboxylic acid substance is 3-thiophene formic acid or 2, 5-dibromo-3-thiophene formic acid, when the thiophene carboxylic acid substance is 3-thiophene formic acid, the obtained metal corrosion inhibitor is TOP-Meth, and when the thiophene carboxylic acid substance is 3-thiophene formic acid, the obtained metal corrosion inhibitor is TOP-MethWhen the acid substance is 2, 5-dibromo-3-thiophenecarboxylic acid, the obtained metal corrosion inhibitor is BTOP-Meth, wherein the structural formula of the 3-thiophenecarboxylic acid is as follows:
the structural formula of TOP-Meth is:
the structural formula of the 2, 5-dibromo-3-thiophenecarboxylic acid is as follows:
the structural formula of BTOP-Meth is as follows:
preferably, the alkaline agent is an organic or inorganic base.
Preferably, the organic base is sodium hydroxide, potassium hydroxide or sodium hydride.
Preferably, the inorganic base is triethylamine, pyridine, diisopropylethylamine or sodium alkoxide.
Preferably, the catalyst is N, N-Dimethylformamide (DMF).
Preferably, the acidic agent is hydrochloric acid or dilute sulfuric acid.
In order to achieve the above object, the present invention further provides a preparation method of the metal corrosion inhibitor, comprising the following steps:
s100: adding 10-30 parts by weight of thiophene carboxylic acid substances into a flask;
s200: adding 50-200 parts by weight of a first solvent and 0-30 parts by weight of an additive into the flask, and continuously stirring for reaction to obtain a solution containing an intermediate, wherein the intermediate is a product obtained by reacting a thiophene carboxylic acid substance and the additive, the first solvent is dichloromethane, trichloromethane or toluene, the additive is oxalyl chloride or thionyl chloride, and when the additive is oxalyl chloride, 0.1-0.5 part by weight of a catalyst needs to be added into the flask;
s300: carrying out reduced pressure evaporation on the solution containing the intermediate to obtain an intermediate, and adding dioxane to dissolve the intermediate;
s400: adding 5-15 parts by weight of methionine and 20-120 parts by weight of alkaline reagent into 10-20 parts by weight of second solvent for dissolving, wherein the second solvent is water or dioxane;
s500: adding the solution obtained in the step S300 into the solution obtained in the step S400, and continuously stirring until the reaction is completed to obtain a solution containing thiophene carboxylate;
s600: adding 10-30 parts by weight of acid into the solution containing thiophene carboxylate for quenching reaction to obtain a solution containing a metal corrosion inhibitor, and then separating and purifying the solution containing the metal corrosion inhibitor to obtain the metal corrosion inhibitor.
Preferably, step S200 specifically includes: adding 50-200 parts by weight of a first solvent into the flask in an ice-water bath, dropwise adding 0-30 parts by weight of an additive and 0.1-0.5 part by weight of a catalyst, and stirring for 2-4 hours to react to obtain a solution containing an intermediate.
Preferably, step S500 specifically includes: and (3) dropwise adding the solution obtained in the step (S300) into the solution obtained in the step (S400) in an ice water bath, and stirring for 6-24 hours to perform reaction so as to obtain a solution containing thiophene carboxylate.
The technical scheme of the invention has the advantages that the thiophene carboxylic acid substance reacts with the additive to generate an intermediate (acyl chloride substance), the intermediate (acyl chloride substance) reacts with methionine in an alkaline environment to generate thiophene carboxylate, the acid reagent and the thiophene carboxylate carry out quenching reaction to obtain the metal corrosion inhibitor, the metal corrosion inhibitor prepared by the method comprises N atoms and/or S atoms, the N atoms and/or S atoms can coordinate with a d-vacant orbit of metal ions to form a coordinate bond, so that metal corrosion inhibitor molecules are adsorbed on the metal surface to form a compact monomolecular film layer on the metal surface, a corrosion medium is isolated from the metal surface, and the corrosion of the metal is slowed down, the metal corrosion inhibitor uses the thiophene carboxylic acid substance, the methionine and the like as raw materials, the raw materials have wide sources and low cost, and the paint is non-toxic, harmless, green and environment-friendly.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the apparatuses shown in the drawings without creative efforts.
FIG. 1 is a flow chart of the present invention for preparing a metal corrosion inhibitor;
FIG. 2 shows that the Q235 steel of the present invention is at 298K, 1mol L-1Electrochemical impedance spectroscopy (Nyquist) graphs of different concentrations of TOP-Meth in HCl solution;
FIG. 3 shows that the Q235 steel of the present invention is at 298K, 1mol L-1Electrochemical impedance spectroscopy (Nyquist) graphs of different concentrations of BTOP-Meth in HCl solution;
FIG. 4 shows 1mol L of the metal corrosion inhibitor of the present invention at 298K without adding-1Equivalent circuit diagram of HCl solution;
FIG. 5 shows that at 298K, 1mol L of TOP-Meth or BTOP-Meth is added-1Equivalent circuit diagram of HCl solution;
FIG. 6 shows the Q235 steel of the present invention at 1mol L-1Scanning electron micrographs of HCl without or with a metal corrosion inhibitor.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly. In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, "and/or" in the whole text includes three schemes, taking a and/or B as an example, including a technical scheme, and a technical scheme that a and B meet simultaneously; in addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The invention provides a metal corrosion inhibitor, which comprises the following components: 10-30 parts by weight of thiophene carboxylic acid substance, 50-200 parts by weight of first solvent, 10-30 parts by weight of additive, 10-20 parts by weight of dioxane, 5-15 parts by weight of methionine, 20-120 parts by weight of alkaline reagent, 10-20 parts by weight of second solvent and 10-30 parts by weight of acidic reagent, wherein the first solvent is dichloromethane, trichloromethane or toluene, the second solvent is water or dioxane, the additive is oxalyl chloride or thionyl chloride, and when the additive is oxalyl chloride, the metal corrosion inhibitor further comprises: 0.1 to 0.5 part by weight of a catalyst.
In the invention, thiophene carboxylic acid substances and additives react to generate intermediates (acyl chlorides), the intermediates (acyl chlorides) and methionine react to generate thiophene carboxylate in an alkaline environment, an acidic reagent and the thiophene carboxylate carry out quenching reaction to obtain the metal corrosion inhibitor, the prepared metal corrosion inhibitor comprises N atoms and/or S atoms, the N atoms and/or S atoms can coordinate with a d-vacant orbit of metal ions to form a coordination bond, so that metal corrosion inhibitor molecules are adsorbed on the surface of metal, a compact monomolecular film layer is formed on the metal surface to isolate the corrosive medium from the metal surface, the metal corrosion inhibitor disclosed by the application uses thiophene carboxylic acid substances, methionine and the like as raw materials, and the raw materials are wide in source, low in cost, non-toxic, harmless, green and environment-friendly.
In this embodiment, the additive reacts with 3-thiophenecarboxylic acid or 2, 5-dibromo-3-thiophenecarboxylic acid to generate an intermediate (an acyl chloride substance), and in this embodiment, when the additive is thionyl chloride, the first solvent may not be added, and thionyl chloride may serve as a reactant and a solvent.
In this embodiment, when the second solvent is water, deionized water is used, and the deionized water refers to pure water from which impurities in the form of ions are removed, so as to prevent the impurities in the form of ions in the water from interfering with the reaction.
Further, the thiophene carboxylic acid substance is 3-thiophene formic acid or 2, 5-dibromo-3-thiophene formic acid, when the thiophene carboxylic acid substance is 3-thiophene formic acid, the obtained metal corrosion inhibitor is TOP-Meth, when the thiophene carboxylic acid substance is 2, 5-dibromo-3-thiophene formic acid, the obtained metal corrosion inhibitor is BTOP-Meth, wherein the structural formula of the 3-thiophene formic acid is as follows:
the structural formula of TOP-Meth is:
the structural formula of the 2, 5-dibromo-3-thiophenecarboxylic acid is as follows:
the structural formula of BTOP-Meth is as follows:
further, the alkaline agent is an organic base or an inorganic base, and in the present embodiment, the alkaline agent is used to provide an alkaline environment.
Further, the organic base is sodium hydroxide, potassium hydroxide or sodium hydride.
Further, the inorganic base is triethylamine, pyridine, diisopropylethylamine or sodium alkoxide.
Further, the catalyst was N, N-Dimethylformamide (DMF).
Further, the acidic reagent is hydrochloric acid or dilute sulfuric acid.
Referring to fig. 1, the present invention provides a preparation method of a metal corrosion inhibitor, comprising the following steps:
s100: adding 10-30 parts by weight of thiophene carboxylic acid substances into a flask;
s200: adding 50-200 parts by weight of a first solvent and 0-30 parts by weight of an additive into a flask, and continuously stirring for reaction to obtain a solution containing an intermediate, wherein the intermediate is a product obtained by reacting a thiophene carboxylic acid substance and the additive, the first solvent is dichloromethane, trichloromethane or toluene, the additive is oxalyl chloride or thionyl chloride, and when the additive is oxalyl chloride, 0.1-0.5 part by weight of a catalyst needs to be added into the flask;
s300: carrying out reduced pressure evaporation on the solution containing the intermediate to obtain an intermediate, and adding dioxane to dissolve the intermediate;
s400: adding 5-15 parts by weight of methionine and 20-120 parts by weight of alkaline reagent into 10-20 parts by weight of second solvent for dissolving, wherein the second solvent is water or dioxane;
s500: adding the solution obtained in the step S300 into the solution obtained in the step S400, and continuously stirring until the reaction is complete to obtain a solution containing thiophene carboxylate;
s600: adding 10-30 parts by weight of an acidic reagent into a solution containing thiophene carboxylate to carry out quenching reaction to obtain a solution containing a metal corrosion inhibitor, and then separating and purifying the solution containing the metal corrosion inhibitor to obtain the metal corrosion inhibitor.
Further, step S200 specifically includes: adding 50-200 parts by weight of a first solvent and 0-30 parts by weight of an additive dropwise into a flask in an ice-water bath, and stirring for 2-4 hours to react to obtain a solution containing an intermediate, wherein the intermediate is a product obtained by reacting a thiophene carboxylic acid substance and the additive, the first solvent is dichloromethane, trichloromethane or toluene, the additive is oxalyl chloride or thionyl chloride, when the additive is oxalyl chloride, 0.1-0.5 part by weight of a catalyst needs to be added into the flask, and specifically, the thiophene carboxylic acid substance and the additive are uniformly mixed and fully reacted in a dropwise manner.
In this embodiment, a large amount of heat is released during the reaction of the thiophene carboxylic acid substance and the additive, and if the temperature of the reaction system is too high, a side reaction may be induced, and an unnecessary product may be generated, so that before the additive is added, the flask is placed in an ice-water bath, which is beneficial for inhibiting the reaction activity in a low-temperature environment, and prevents the temperature of the reaction system from being too high due to concentrated heat release.
In this example, the thiophenecarboxylic acid compound is 3-thiophenecarboxylic acid or 2, 5-dibromo-3-thiophenecarboxylic acid, the intermediate is 3-thiophenecarbonyl chloride when the thiophenecarboxylic acid compound is 3-thiophenecarboxylic acid, and the intermediate is 2, 5-dibromo-3-thiophenecarbonyl chloride when the thiophenecarboxylic acid compound is 2, 5-dibromo-3-thiophenecarboxylic acid, wherein the 3-thiophenecarbonyl chloride has the formula
The structural formula of the 2, 5-dibromo-3-thiophene formyl chloride is shown in the specification
In this embodiment, the step S300 is to evaporate the solution containing the intermediate under reduced pressure to remove the excess first solvent and the additive from the solution containing the intermediate.
Further, step S500 specifically includes: dropwise adding the solution obtained in the step S300 into the solution obtained in the step S400 in an ice water bath, and stirring for 6-24 hours to perform a reaction, so as to obtain a solution containing thiophene carboxylate, specifically, dropwise adding the solution obtained in the step S300, so that the solution obtained in the step S300 and the solution obtained in the step S400 are uniformly mixed and sufficiently reacted, and in this embodiment, thiophene carboxylate is related to an alkaline reagent, such as: the thiophene carboxylate is a sodium salt when the basic agent is sodium hydroxide, a potassium salt when the basic agent is potassium hydroxide, and an amine salt when the basic agent is triethylamine.
In this embodiment, since the solution obtained in step S300 and the solution obtained in step S400 release a large amount of heat during the reaction, and if the temperature of the reaction system is too high, a side reaction may be induced, and an unnecessary product may be generated, therefore, before the solution obtained in step S300 is added, the solution obtained in step S400 is placed in an ice water bath, and the low-temperature environment is favorable for inhibiting the reaction activity, and preventing the temperature of the reaction system from being too high due to concentrated heat release.
In step S600, the acidic reagent is hydrochloric acid or dilute sulfuric acid, and the acid is used to eliminate the alkaline reagent in the reaction to ensure that the reaction product is stable.
The separation and purification in step S600 includes: after the solution containing the metal corrosion inhibitor is extracted, the solution containing the metal corrosion inhibitor is purified by a column chromatography, and particularly, the separation and purification are simple in operation and high in purification rate.
The extraction of the solution comprising the metal corrosion inhibitor comprises: the solution containing the metal corrosion inhibitor is extracted with a water-insoluble organic solvent, which may be, but is not limited to, dichloromethane or ethyl acetate.
The technical scheme of the invention is further described below by combining a plurality of specific embodiments, so that the purpose and the advantages of the invention are clear.
The first embodiment is as follows:
the preparation method of the metal corrosion inhibitor of the embodiment is carried out according to the following steps:
s100: 0.64g of 3-thiophenecarboxylic acid was weighed into a 100mL round-bottom flask.
S200: under an ice-water bath, 50mL of dichloromethane was added to the round bottom flask, and oxalyl chloride (COCl) was added dropwise20.8mL, 3 drops of N, N-Dimethylformamide (DMF) were added dropwise thereto, and the mixture was stirred for 2 to 4 hours.
S300: the dichloromethane solvent and excess oxalyl chloride were removed by evaporation under reduced pressure to give an intermediate, and 10mL of dioxane was added to dissolve the intermediate.
S400: 0.746g methionine was weighed out using a scale, 0.4g sodium hydroxide (NaOH) was weighed out using a scale, and 5mL deionized water was added for dissolution.
S500: and (3) sucking the solution obtained in the step (S300) by using an injector, dropwise adding the solution into the solution obtained in the step (S400) in an ice water bath, keeping stirring in the injection process, and keeping stirring for 6-24 hours after the injection is finished so as to obtain a solution containing thiophene carboxylate.
S600: and after the reaction is finished, adding excessive hydrochloric acid (HCL) to carry out quenching reaction on the solution containing the thiophene carboxylate to obtain a solution containing the metal corrosion inhibitor, then extracting the solution containing the metal corrosion inhibitor by using ethyl acetate, and after the extraction is finished, carrying out column chromatography separation to obtain the metal corrosion inhibitor (TOP-Meth).
In the embodiment, 3-thiophenecarboxylic acid is used as a reaction raw material, 3-thiophenecarboxylic acid and methionine are used as raw materials, sodium hydroxide is added, deionized water is used as a solvent, the temperature is naturally restored to a room temperature state from 0 ℃ in the reaction process, the reaction is carried out for 6 hours, and the metal corrosion inhibitor is obtained after separation and purification.
The reaction procedure of this example is as follows:
wherein, 0 ℃ to r.t means that the reaction temperature is from 0 ℃ to room temperature,
is a methionine, and is a methionine,
is thiophene carboxylate.
To verify the corrosion inhibition effect of the metal corrosion inhibitor in this example, Q235 steel was placed in 1mol L of metal corrosion inhibitor containing different concentrations-1In HCl solution, various tests were performed:
1. weight loss experiment
1mol L of TOP-Meth and BTOP-Meth in the absence or presence of different concentrations-1Weight loss experiments are carried out in HCl solution, the corrosion rate and the corrosion inhibition efficiency of Q235 steel in the system are calculated by using a formula 2-1, the results are shown in Table 1, and the results in Table 1 show that two methionine derivatives are 1mol L of Q235 steel-1The corrosion in the HCl solution is excellent. The corrosion rate is related to the concentration of TOP-Meth and BTOP-Meth, and the corrosion inhibition efficiency is gradually improved with the increase of the concentration of the two substances and reaches the maximum value at 200 mg/L. The inhibition effect of TOP-Meth and BTOP-Meth on the corrosion of Q235 steel can be attributed to the adsorption of TOP-Meth and BTOP-Meth on the surface of Q235 steel, limiting the dissolution of Q235 steel by blocking its corrosion sites, thereby reducing the corrosion rate. The free electrons of the corrosion inhibitor are easy to interact with the d-vacant orbital of the metal to form a surface complex, so that the compounds TOP-Meth and BTOP-Meth are supposed to form a donor-acceptor surface complex by the interaction of the lone pair of electrons of N, S and O atoms and the d-vacant orbital of the Fe on the surface of Q235. Thereby blocking corrosion sites on the surface of the Q235 steel.
Calculated from equation 2-1:
v-Corrosion Rate (g m)-2h-1)；
Δ W-Mass poor (g);
s-surface area of sample (m)2)；
TABLE 1 weight loss test results for Q235 steels in HCl solutions without or with different concentrations of metal corrosion inhibitors
2. Tafel (Tafel) extrapolation
The corrosion current density (i) of the Q235 steel electrode surface is obtained by Tafel extrapolationcorr) The corrosion potential, the cathode and anode Tafel slope and other parameters, and related parameters are shown in the table 2, and the corrosion rate and the corrosion slowing efficiency of the Q235 steel in the system are calculated by using a formula 2-2. As can be seen from the table, in the blank control, the corrosion current density (i)corr) Is 74.65mA cm-2Adding 200mg L-1After TOP-Meth and BTOP-Meth, the corrosion current density drops sharply to 20.45mA cm respectively-2And 11.11mA cm-2The corrosion inhibition rates respectively reach 75.07% and 86.46%, which shows that the corrosion prevention effect is good. In addition, the change of the corrosion potential value after adding TOP-Meth and BTOP-Meth is obviously less than 85mV, which also indicates that the two thiophene amino acid derivatives belong to mixed corrosion inhibitors. In summary, TOP-Meth and BTOP-Meth are two cathode-based mixed corrosion inhibitors.
Calculated from equation 2-2:
eta-corrosion inhibition efficiency; i.e. icorr-corrosion current;
-corrosion current of blank HCI solution.
TABLE 2 zeta potential polarization parameters of Q235 steels in the absence or presence of various concentrations of metal corrosion inhibitors HCl
3. Electrochemical impedance experiment, measuring impedance parameters
FIG. 2 and FIG. 3 show that the Q235 steel is at 298K, 1mol L-1Electrochemical impedance spectrograms of different concentrations of TOP-Meth and BTOP-Meth in solution. As can be seen from FIG. 2 and FIG. 3, after adding TOP-Meth and BTOP-Meth into HCl solution, the diameter of the capacitor arc is significantly increased, which shows that TOP-Meth and BTOP-Meth can form an effective barrier film layer on the surface of Q235 steel/solution, and the charge transfer resistance (R) is improvedct) And the corrosion of the Q235 steel is effectively inhibited. And the radius of the capacitor arc shows a tendency to increase with increasing concentrations of TOP-Meth and BTOP-Meth. In addition, all the capacitor arcs were flat and semicircular, indicating that the addition of TOP-Meth and BTOP-Meth did not significantly alter the etch mechanism. While the centers of all the semi-circles are significantly lower than the X-axis, which is a result of the uneven formation of the protective film on the Q235 steel/solution surface by TOP-Meth and BTOP-Meth. As can be seen from the electrochemical impedance spectrogram, the radius of the capacitance arc of the system added with BTOP-Meth is larger than that of the system added with TOP-Meth, which indicates that the corrosion inhibition capability of BTOP-Meth is stronger than that of TOP-Meth.
The charge transfer resistance obtained by electrochemical impedance spectroscopy measurements can be used to calculate corrosion inhibition efficiency, to simulate impedance parameters and to simulate an equivalent circuit for electrochemical behavior, see fig. 4 and 5, where solution resistance (R) iss) Charge transfer resistance (R)ct) Solution film layer resistance (R)f) Constant phase angle element CPE (Q)dl) Solution film layer constant phase angle element (Q)f) The iso-electrochemical impedance fit data are shown in table 3, and the corrosion rate and corrosion efficiency of Q235 steel in this system were calculated using equations 2-3.
From the results in Table 3, it can be seen that the corrosion inhibition efficiency increases with increasing corrosion inhibitor concentration. At 200mg L-1When the corrosion inhibition efficiency is highest, the corrosion inhibition efficiency reaches 90.21% and 95.34% respectively. TOP-Meth and BTOP-Meth contain N, S atoms, donate lone pair electrons and pi electrons to the empty orbit of iron, so that these molecules can be strongly adsorbed on the surface of Q235 steel to prevent corrosive media such as O2、H+And the like. RpThe value is increased, more corrosion inhibitor molecules on the surface are adsorbed to the surface of Q235 steel, and a more complete film is formed.
Calculated from equations 2-3:
in the formula Rp＝Rs+Rct+Rf；
R corresponding to blank HCI solutionp；Rs-solution resistance; rct-a charge transfer resistance; rfSolution film layer resistance.
TABLE 3 impedance parameters of HCl solutions without or with different concentrations of metal corrosion inhibitors
4. Surface topography analysis of scanning electron microscope
FIG. 6 shows the surface morphology of Q235 steel after being soaked in a solution without and with TOP-Meth and BTOP-Meth for 12 h. The initial morphology of the Q235 steel is shown in fig. 6a), and it can be seen that the surface is entirely smooth, with only small traces due to factory cutting. As shown in fig. 6b), after the blank HCl solution is soaked for 12 hours, the corrosion degree of the Q235 steel is significantly increased, a plurality of irregular cracks and pits appear on the surface, and the corrosion holes become large and deep. In contrast, the degree of corrosion suffered by the surface of Q235 steel after 12h of immersion in HCl solution with the addition of TOP-Meth and BTOP-Meth was greatly reduced, which demonstrates that TOP-Meth and BTOP-Meth are effective at 1mol L for Q235 steel-1The HCl solution has excellent corrosion resistance. As can be seen by comparing FIG. 6c) with FIG. 6d), the surface of the Q235 steel with the added TOP-Meth still shows a small number of pores due to corrosion, while the surface of the Q235 steel with the added BTOP-Meth is smoother and flatter, closer to the original morphology. Also shows that the corrosion inhibition effect of BTOP-Meth is more excellent than that of TOP-Meth, which is also similar to the previous weight loss experiment and electrochemistryThe results of the experiments were consistent.
In conclusion, the amino acid amide compound prepared by adopting methionine (Meth) as a reaction raw material has a certain corrosion inhibition effect when being used as a metal corrosion inhibitor.
Example two:
the difference between this embodiment and the first embodiment is: in the preparation method of the metal corrosion inhibitor, 2, 5-dibromo-3-thiophenecarboxylic acid is used as a reaction raw material instead of 3-thiophenecarboxylic acid.
The preparation method of the metal corrosion inhibitor of the embodiment is carried out according to the following steps:
s100: 0.857g of 2, 5-dibromo-3-thiophenecarboxylic acid was weighed and charged into a 100mL round-bottomed flask.
S200: under an ice-water bath, 50mL of dichloromethane was added, and oxalyl chloride (COCl) was added dropwise20.5mL, 2 drops of N, N-Dimethylformamide (DMF) were added dropwise thereto, and the mixture was stirred for 2 to 4 hours.
S300: the dichloromethane solvent and excess oxalyl chloride were removed by evaporation under reduced pressure to give an intermediate, and 10mL of dioxane was added to dissolve the intermediate.
S400: 0.447g of methionine was weighed out using a scale, 0.24g of sodium hydroxide (NaOH) was weighed out using a scale, and 5mL of deionized water was added for dissolution.
S500: and (3) sucking the solution obtained in the step (S300) by using an injector, dropwise adding the solution into the solution obtained in the step (S400) in an ice water bath, keeping stirring in the injection process, and keeping stirring for 6-24 hours after the injection is finished so as to obtain a solution containing thiophene carboxylate.
S600: and after the reaction is finished, adding excessive hydrochloric acid (HCL) to carry out quenching reaction on the solution containing the thiophene carboxylate to obtain a solution containing the metal corrosion inhibitor, then extracting the solution containing the metal corrosion inhibitor by using ethyl acetate, and separating by using column chromatography to obtain the metal corrosion inhibitor (BTOP-Meth).
The reaction procedure of this example is as follows:
example three:
the preparation method of the metal corrosion inhibitor of the embodiment is carried out according to the following steps:
s100: 0.857g of 2, 5-dibromo-3-thiophenecarboxylic acid was weighed and charged into a 100mL round-bottomed flask.
S200: and adding 10mL of thionyl chloride in an ice water bath, heating to the reflux temperature, and stirring for 2-4 hours.
S300: excess thionyl chloride was evaporated under reduced pressure to give an intermediate, and 10mL of dioxane was added to dissolve the intermediate.
S400: 0.447g of methionine was weighed out using a scale, 0.24g of sodium hydride was weighed out using a scale, and 5mL of deionized water was added for dissolution.
S500: and (3) sucking the solution obtained in the step (S300) by using an injector, dropwise adding the solution into the solution obtained in the step (S400) in an ice water bath, keeping stirring in the injection process, and keeping stirring for 6-24 hours after the injection is finished so as to obtain a solution containing thiophene carboxylate.
S600: and after the reaction is finished, adding excessive hydrochloric acid (HCL) to carry out quenching reaction on the solution containing the thiophene carboxylate to obtain a solution containing the metal corrosion inhibitor, then extracting the solution containing the metal corrosion inhibitor by using ethyl acetate, and separating by using column chromatography to obtain the metal corrosion inhibitor (BTOP-Meth).
Example four:
the preparation method of the metal corrosion inhibitor of the embodiment is carried out according to the following steps:
s100: 0.857g of 2, 5-dibromo-3-thiophenecarboxylic acid was weighed and charged into a 100mL round-bottomed flask.
S200: 50mL of dichloromethane was added under ice-water bath, and oxalyl chloride (COCl) was added dropwise20.5mL, 2 drops of N, N-Dimethylformamide (DMF) were added dropwise thereto, and the mixture was stirred for 2 to 4 hours.
S300: the dichloromethane solvent and excess oxalyl chloride were removed by evaporation under reduced pressure to give an intermediate, and 10mL of dioxane was added to dissolve the intermediate.
S400: 0.447g of methionine was weighed out using a scale, 0.34g of potassium hydroxide was weighed out using a scale, and 5mL of dioxane was added for dissolution.
S500: and (3) sucking the solution obtained in the step (S300) by using an injector, dropwise adding the solution into the solution obtained in the step (S400) in an ice water bath, keeping stirring in the injection process, and keeping stirring for 6-24 hours after the injection is finished so as to obtain a solution containing thiophene carboxylate.
S600: and after the reaction is finished, adding excessive hydrochloric acid (HCL) to carry out quenching reaction on the solution containing the thiophene carboxylate to obtain a solution containing the metal corrosion inhibitor, then extracting the solution containing the metal corrosion inhibitor by using ethyl acetate, and separating by using column chromatography to obtain the metal corrosion inhibitor (BTOP-Meth).
Example five:
the preparation method of the metal corrosion inhibitor of the embodiment is carried out according to the following steps:
s100: 0.64g of 3-thiophenecarboxylic acid was weighed into a 100mL round-bottom flask.
S200: 50mL of dichloromethane was added under ice-water bath, and oxalyl chloride (COCl) was added dropwise20.5mL, 2 drops of N, N-Dimethylformamide (DMF) were added dropwise thereto, and the mixture was stirred for 2 to 4 hours.
S300: the dichloromethane solvent and excess oxalyl chloride were removed by evaporation under reduced pressure to give an intermediate, and 10mL of dioxane was added to dissolve the intermediate.
S400: a celestial balance was used to measure 0.447g of methionine, a measuring cylinder was used to measure 0.84mL of triethylamine, and 5mL of deionized water was added for dissolution.
S500: and (3) sucking the solution obtained in the step (S300) by using an injector, dropwise adding the solution into the solution obtained in the step (S400) in an ice water bath, keeping stirring in the injection process, and keeping stirring for 6-24 hours after the injection is finished so as to obtain a solution containing thiophene carboxylate.
S600: and after the reaction is finished, adding excessive hydrochloric acid (HCL) to carry out quenching reaction on the solution containing the thiophene carboxylate to obtain a solution containing the metal corrosion inhibitor, then extracting the solution containing the metal corrosion inhibitor by using ethyl acetate, and after the extraction is finished, carrying out column chromatography separation to obtain the metal corrosion inhibitor (TOP-Meth).
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A metal corrosion inhibitor, comprising:
thiophene carboxylic acid species: 10-30 parts by weight;
a first solvent: 50-200 parts by weight;
addition of: 10-30 parts by weight;
dioxane: 10-20 parts by weight;
methionine: 5-15 parts by weight;
alkaline reagent: 20-120 parts by weight;
a second solvent: 10-20 parts by weight;
acid reagent: 10-30 parts by weight;
wherein, the first solvent is dichloromethane, trichloromethane or toluene, the second solvent is water or dioxane, the additive is oxalyl chloride or thionyl chloride, and when the additive is oxalyl chloride, the metal corrosion inhibitor further comprises: 0.1 to 0.5 part by weight of a catalyst.
2. The metal corrosion inhibitor according to claim 1, wherein the thiophenecarboxylic acid species is 3-thiophenecarboxylic acid or 2, 5-dibromo-3-thiophenecarboxylic acid, wherein when the thiophenecarboxylic acid species is 3-thiophenecarboxylic acid, the metal corrosion inhibitor obtained is TOP-Meth, and when the thiophenecarboxylic acid species is 2, 5-dibromo-3-thiophenecarboxylic acid, the metal corrosion inhibitor obtained is BTOP-Meth, wherein the 3-thiophenecarboxylic acid has the formula:
the structural formula of TOP-Meth is:
the structural formula of the 2, 5-dibromo-3-thiophenecarboxylic acid is as follows:
the structural formula of BTOP-Meth is as follows:
3. the metal corrosion inhibitor of claim 1 wherein the alkaline agent is an organic or inorganic base.
4. The metal corrosion inhibitor of claim 3 wherein said organic base is sodium hydroxide, potassium hydroxide or sodium hydride.
5. The metal corrosion inhibitor of claim 3 wherein the inorganic base is triethylamine, pyridine, diisopropylethylamine or sodium alkoxide.
6. The metal corrosion inhibitor of claim 1 wherein said catalyst is N, N-Dimethylformamide (DMF).
7. The metal corrosion inhibitor of claim 1 wherein said acidic agent is hydrochloric acid or dilute sulfuric acid.
8. The preparation method of the metal corrosion inhibitor is characterized by comprising the following steps:
s100: adding 10-30 parts by weight of thiophene carboxylic acid substances into a flask;
s200: adding 50-200 parts by weight of a first solvent and 0-30 parts by weight of an additive into the flask, and continuously stirring for reaction to obtain a solution containing an intermediate, wherein the intermediate is a product obtained by reacting a thiophene carboxylic acid substance and the additive, the first solvent is dichloromethane, trichloromethane or toluene, the additive is oxalyl chloride or thionyl chloride, and when the additive is oxalyl chloride, 0.1-0.5 part by weight of a catalyst needs to be added into the flask;
s300: carrying out reduced pressure evaporation on the solution containing the intermediate to obtain an intermediate, and adding dioxane to dissolve the intermediate;
s400: adding 5-15 parts by weight of methionine and 20-120 parts by weight of alkaline reagent into 10-20 parts by weight of second solvent for dissolving, wherein the second solvent is water or dioxane;
s500: adding the solution obtained in the step S300 into the solution obtained in the step S400, and continuously stirring until the reaction is completed to obtain a solution containing thiophene carboxylate;
s600: adding 10-30 parts by weight of an acidic reagent into the solution containing thiophene carboxylate for quenching reaction to obtain a solution containing a metal corrosion inhibitor, and then separating and purifying the solution containing the metal corrosion inhibitor to obtain the metal corrosion inhibitor.
9. The method for preparing a metal corrosion inhibitor according to claim 8, wherein the step S200 specifically comprises: adding 50-200 parts by weight of a first solvent into the flask in an ice-water bath, dropwise adding 0-30 parts by weight of an additive and 0.1-0.5 part by weight of a catalyst, and stirring for 2-4 hours to react to obtain a solution containing an intermediate.
10. The method for preparing a metal corrosion inhibitor according to claim 8, wherein step S500 specifically comprises: and (3) dropwise adding the solution obtained in the step (S300) into the solution obtained in the step (S400) in an ice water bath, and stirring for 6-24 hours to perform reaction so as to obtain a solution containing thiophene carboxylate.
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