Anti-corrosion protection of carbon steel with lidocaine in hydrogen sulfide-containing environments

• L.E. Tsygankova¹, V.A. Kur’yato¹, F.A. Aidemirova¹, U.V. Baisheva¹ and N.V. Shel²

¹ Derzhavin State University, ul. Internatsionalnaya, 33, 392000 Tambov, Russian Federation
² Tambov State Technical University, ul. Sovetskaya, 106, 392000 Tambov, Russian Federation

Abstract: In the past decade, active researches of expired drugs as inhibitors of metal corrosion are being conducted in various aggressive environments. In this work, the inhibitory effect of the expired drug Lidocaine was studied against corrosion of carbon steel in NACE and M1 model stratum waters of oil and gas fields containing 400 mg/L H₂S.The concentration of the drug varied within 20–80 mg/L. The protective effect (Z) of Lidocaine (80 mg/L) is 81% and 86%, according to daily gravimetric tests, respectively, in NACE and M1 media. At 80°C, the Z value increases to 85% and 95%, respectively. An analysis of the polarization curves in the media under study showed that Lidocaine slows down the cathode process in the NACE+H₂S medium and both partial electrode reactions in M1+H₂S. According to impedance spectroscopy data, the surface coverage of the electrode by the inhibitor was calculated. The adsorption of Lidoсaine follows the Langmuir isotherm. A value of the free energy of adsorption indicates the physical nature of the drug adsorption.

Keywords: expired drug, Lidocaine, carbon steel, corrosion, inhibition, adsorption, protective efficiency

Int. J. Corros. Scale Inhib., 2025, 14, no. 1, 288-299
doi: 10.17675/2305-6894-2025-14-1-18

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