Prediction and Measurements of Corrosion Inhibition of Mild Steel C1018 using Some Natural Naphthenate Surfactants in CO2-Saturted NaCl Solution

摘要

The efficiency of two natural naphthenate surfactants (Naphthenic-dimethylamine and Naphthenic-diethylamine complexes) as corrosion inhibitors for mild steel in CO2-saturated 1% NaCl solution has been determined by linear polarization resistance corrosion rate and potentiodynamic polarization measurements. These compounds inhibit corrosion even at very low concentrations (25 ppm) and Naphthenic-diethylamine complex is the best inhibitor giving maximum inhibition efficiency 99.76 at 100 ppm. Polarization curves indicate that the two investigated compounds are mixed inhibitors, affecting both cathodic and anodic corrosion currents. Adsorption of naphthenates surfactants on the mild steel surface is in agreement with the Langmuir Adsorption Isotherm Model and the calculated Gibbs free energy values confirm the chemical nature of the adsorption. Energy Dispersive X-Ray Fluorescence microscopy (EDRF) observations confirmed the existence of such an adsorbed film on the mild steel surface.