Corrosion Inhibition and Adsorption Behavior of Some Cationic Surfactants on Carbon Steel in Hydrochloric Acid Solution

Abstract

The corrosion protection of Cetylpyridinium bromide (CPB) and Cetyltrimethylammonium bromide (CTAB) as cationic surfactant on the corrosion of C-steel in 1 M hydrochloric acid has been studied by weight loss, Tafel polarization, electrochemical impedance spectroscopy, and electrochemical frequency modulation techniques. The carbon steel samples were also analyzed by scanning electron microscopy. The % protection efficiency increases with increasing concentration of the surfactants and decreases with temperature rise. The % protection efficiency reached to 94 % at a concentration of 150 ppm. The protection of C-steel by these surfactants was attributed to the synergistic effect between bromide anions and positive quaternary ammonium ions. The charge transfer resistance increased and double layer capacitance decreased. Surfactant molecules adsorbed on the surface of steel obeys Langmuir adsorption isotherm.