Synergism of CTAB and NLS surfactants on the corrosion inhibition of mild steel in sodium chloride solution

Abstract

The inhibition effects of CTAB and NLS surfactants on the corrosion of mild steel in 3.5% sodium chloride solution at temperatures of 25, 40, and 55 °C were investigated using the Tafel potentiodynamic polarization, electrochemical impedance spectroscopy, weight loss, and SEM methods. At all studied temperatures, by adding the surfactant to the corrosive solution the corrosion rate of steel was reduced significantly. The inhibition effect of both surfactants decreased at higher temperatures. The adsorption of CTAB and NLS on the surface of steel obeyed the Langmuir isotherm and was of mixed type. The synergistic effect of two surfactants was also investigated and results showed that when the mixture of surfactants was used the inhibition efficiency was effectively improved compared to individual surfactants. The maximum inhibition efficiency of about 98% was obtained for the mixture of CTAB+NLS surfactants.