Experimental and computational studies of cationic Gemini surfactants as corrosion inhibitors for carbon steel in 15% HCl

Abstract

In the process of oil and gas exploration, the corrosion of carbon steel pipes results in substantial economic losses, numerous casualties, environmental contamination, and resource waste. The advancement of highly efficient and stable corrosion inhibitors holds significant importance for protecting carbon steel from corrosion during oil and gas exploitation. In this study, two new cationic Gemini surfactants (2C_ncoesT, where n = 12, 14) were synthesized through a straightforward two-step reaction. Weight-loss tests demonstrated that the inhibition efficiency (η_w%) increases with the increase in temperature. Specifically, the maximum η_w% values for 2C₁₂coesT and 2C₁₄coesT were 98.0% and 98.3% respectively at 85 °C. The adsorption of these surfactants conformed to the Langmuir adsorption isotherm. Electrochemical measurements suggested that the two surfactants functioned as mixed-type inhibitors. The findings obtained from scanning electron microscopy (SEM) were consistent with the experimental outcomes that 2C₁₂coesT and 2C₁₄coesT are efficient corrosion inhibitors for the metal in an acidic environment. The quantum chemical investigation and molecular dynamics simulation (MD) further substantiated the experimental results and offered insights for a deeper comprehension of the inhibition mechanism of Gemini surfactants.