Corrosion inhibition performance of a hybrid organic–inorganic EDFS-1 inhibitor for steel evaluated by gravimetric, electrochemical, SEM and AFM methods

• Z.Kh. Misirov¹, S.Ch. Eshkaraev², Kh.Ch. Mirzakulov³, B.A. Normurodov⁴, G.J. Mukumova⁴, G.E. Melikulova⁵, K.S. Arifdjanova⁵, J.A. Khalilov^5,6 and Sh. Botirov⁷

¹ Department of Chemical Engineering, Termez State University of Engineering and Agrotechnologies, Termez, 190100, Uzbekistan
² Department of Medicine, Termez University of Economics and Service, Termez, Uzbekistan
³ Network Center for “Retraining and Advanced Training of Pedagogical Personnel” at the Tashkent Institute of Chemical Technology, Tashkent, 100011, Uzbekistan
⁴ Faculty of Chemistry, Termez State University, Termez, 190100 Uzbeksitan
⁵ Department of Chemical Technology of Inorganic Substances Tashkent Institute of Chemical Technology, Navoi 32, Tashkent, 100011, Uzbekistan
⁶ Department of Oil and Gas, Karshi University of Economics and Pedagogy, Karshi, Uzbekistan
⁷ Department of Oil and Gas and Mining, Termez State University of Engineering and Agrotechnologies, Termez, 190100, Uzbekistan

Abstract: This study reports the synthesis, characterization, and corrosion inhibition performance of a novel inhibitor, EDFS-1, prepared from ethylenediaminetetraacetic acid (EDTA), sodium metasilicate, and phosphoric acid. The optimal molar ratio of 1:3:1 was determined by gravimetric screening, providing the highest inhibition efficiency. EDFS-1 was evaluated for St20 steel in industrial water containing CO₂, H₂S, and their mixture, showing 84.6–94.2% inhibition at 100 mg/L, depending on the gas environment. In acidic media (0.5–1 M HCl), inhibition efficiency increased with concentration and temperature, reaching 92.98% in 0.5 M HCl and 93.75% in 1 M HCl at 333 K and 150 mg/L. Electrochemical measurements indicated that EDFS-1 significantly reduced corrosion current density while minimally affecting corrosion potential. Surface analyses (SEM and AFM) demonstrated smoother, less pitted steel surfaces in the presence of EDFS-1, confirming the formation of a protective adsorbed film. These results highlight EDFS-1 as an effective and thermally stable inhibitor for steel in CO₂–H₂S-containing waters and strongly acidic environments.

Int. J. Corros. Scale Inhib., 2026, 15, no. 1, 304-319
doi: 10.17675/2305-6894-2026-15-1-15

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