Composite pickling inhibitor containing Schiff base and preparation method of composite pickling inhibitor

Abstract

The invention belongs to the technical field of carbon steel acid pickling, and discloses a composite pickling inhibitor containing Schiff base and a preparation method of the composite pickling inhibitor. The preparation method of the composite pickling inhibitor comprises the following steps: adding 60 mL of a trichloromethane solution in a three-necked flask, then adding 5.35 g of pyridine-2-formaldehyde and 7.45 g of methionine, magnetically stirring, heating and refluxing for 1 h until all solids are totally dissolved, dropwise adding 5 drops of glacial acetic acid as a catalyst and adjusting the pH value of reaction liquid, continuing to heat and carry out refluxing reaction for 24 h, then stirring and reacting for 2 h at the room temperature, placing reaction liquid in a refrigerator for cooling and crystallizing, carrying out suction filtration under reduced pressure to remove a solvent to obtain brown solids, carrying out recrystallization via methanol, drying under vacuum toobtain a methionine Schiff base derivative, weighing the methionine Schiff base derivative and sodium carboxymethylcellulose and compounding the methionine Schiff base derivative and the sodium carboxymethylcellulose according to a certain mass ratio to obtain the composite pickling inhibitor. The provided composite pickling inhibitor has excellent buffering performance for carbon steel metal in 0.5 M of a hydrochloric acid solution, the corrosion inhibition efficiency can reach 94% or above, the use amount of a corrosion inhibitor is small, and the shortcoming of a single methionine corrosioninhibitor in a using process is overcome.

Description

technical field [0001] The invention belongs to the technical field of carbon steel pickling, and in particular relates to a composite corrosion inhibitor and a preparation method thereof, specifically a methionine Schiff base derivative 2-(N-pyridylmethylimine)-4-methylsulfide The invention discloses a compound corrosion inhibitor of methyl butyric acid (MD) and sodium carboxymethylcellulose (MD) and a preparation method thereof. Background technique [0002] As one of the important methods of chemical cleaning, pickling is widely used in scale removal and rust removal of carbon steel equipment (including boilers, power systems, heat exchangers, etc.) and its components due to its fast and efficient characteristics. As the most commonly used acid for pickling, hydrochloric acid reacts chemically with the scale or rust layer on the metal surface, and at the same time dissolves the carbon steel matrix, causing varying degrees of corrosion to equipment and its components, whic...

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Problems solved by technology

[0004] (1) A single methionine is used as a carbon steel pickling corrosion inhibitor, because of its simple molecular structure and insufficient adsorption on the metal surface, resulting in low corrosion inhibition efficiency and unable to meet the needs of practical applications

[0005] (2) When methionine is used as a corrosion inhibitor for carbon steel pickling, in order to obtain a higher corrosion inhibition efficiency, a larger dosage is often required, resulting in increased costs, waste of resources and environmental pollution, which limits the use of methionine as a corrosion inhibitor development application

[0006] (3) At present, the synthesis method of methionine derivatives that inserts various groups through amidation reaction has disadvantages such as harsh reaction conditions, complicated steps, expensive reagents, and high toxicity, which limit its application and development

[0007] (4) The methionine composite corrosion inhibition system mainly focuses on the synergistic corrosion inhibition between methionine and other amino acids, methionine and small organic molecules or inorganic compounds. These composite corrosion inhibition systems generally have low corrosion inhibition efficiency, or the toxicity of compound compounds Large, expensive and other issues, unable to meet the needs of practical applications

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