Inhibiting formulations against hydrogen sulfide corrosion of carbon steel

• L.E. Tsygankova, A.A. Uryadnikov, A.E. Abramov and T.V. Semenyuk

Derzhavin State University, ul. Internatsyonalnaya, 33, 392000 Tambov, Russian Federation

Abstract: The methods of gravimetry, potentiodynamic polarization, impedance spectroscopy and electrochemical diffusion technique were used to study the protective efficiency of two mixed inhibiting formulations with respect to corrosion of carbon steel in model stratum waters saturated with H2S and H2S+CO2. The imitations of the stratum waters of NACE and the Samotlor oil field (M1) were used. The compositions of the inhibiting mixtures are as follows: 1 – Complex imidazole esters, phosphates with organic radicals, mercaptoalcohol, ethylene glycols, alcohol; 2 – Imidazolines ethoxylated with radicals (of fatty acids), alkylammonium salts, ethylene glycols. Data were obtained on their protective effectiveness and mechanism of action based on gravimetric, polarization and impedance measurements. The electrochemical diffusion technique made it possible to assess their effect on the diffusion of hydrogen through a steel membrane. In the NACE environment, both inhibiting formulations cause inhibition of the cathodic process, in the M1 environment, on the contrary, the anodic process and stimulate a hydrogen diffusion into the metal. A decrease in the double-layer capacitance upon the introduction of inhibiting formulations into the media indicates the adsorption of their components on the metal surface. The investigated inhibiting formulations show, in general, an average efficiency of the order of 50%≤Z<74% at a concentration of 200 mg/L.

Keywords: corrosion, steel, mixed inhibitors, protection, hydrogen sulfide, carbon dioxide, kinetics, diffusion

Int. J. Corros. Scale Inhib., 2022, 11, no. 1, 102-110
doi: 10.17675/2305-6894-2021-11-1-5

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