Devising a corrosion inhibitor for steel ST37-2 in a water-oil mixture

Corrosion elimination implies the application of corrosion-resistant alloys, which is associated with high costs and is not a reliable enough technique, as well as corrosion inhibitors, which need to be constantly improved to improve their efficiency and bring down the cost. As corrosion is characterized by the destruction of a material as a result of interaction with the environment, one of the expedient methods for its minimization is the use of inhibitors. Therefore, it is a relevant task for environmental protection and economic development of the country to devise effective means to protect metals against corrosion. The reported inhibitor AC-2 (the solution of a mixture of 2-alkylimidazolines in methanol) rather effectively protects steel against corrosion in water-oil mixtures at the high concentrations of mineral salts in water. The efficacy of the inhibitor is almost unaffected by the ratio of the volumes of oil and concentrated aqueous solutions of sodium chloride. When using the inhibitor at a concentration of 50 mg/dm3, the degree of protection of steel against corrosion exceeded 90 %. This is due to the fact that the protection of steel against corrosion occurs through the adsorption of the imidazoline components at the metal surface and the adsorption of organic oil components on the hydrophobic alkyl groups of 2-alkylimidazolines. In this case, the hydrophobization of the metal surface proceeds in the presence of minor quantities of oil. It has been shown that in the mixture that contained 200 cm3 of a 3 % sodium chloride solution and 800 cm3 of oil at the concentration of acetic acid, respectively, 0.5 and 3.0 g/dm3 at a temperature of 80 °C at a dose of the inhibitor of 15‒50 mg/dm3 the efficiency reached 72−92 %. This makes it possible to resolve the issue of the rational use of natural resources and ensures the transition to the application of environmentally safe and energy-efficient technologies