Understanding Different Inhibition Actions of Surfactants for Mild Steel Corrosion in Acid Solution

The inhibition actions of different surfactants for corrosion of mild steel were studied by electrochemical impedance spectroscopy and polarization measurements and weight loss. Cationic surfactant: cetylpyridinium bromide (CPBr), non-ionic surfactant: triton (TX-100) and anionic surfactant: dodecyl benzene sulphonate (DBS) in 1 M H2SO4. The order of the determined protection efficiency was found to be CPBr > TX-100 > DBS, due to the differences in the molecular structures of the three surfactants. The adsorption extent of CPBr was found to be higher than both TX-100 and DBS. A positive shift in the value of E-pzc in presence of the CPBr was attributed to the specific adsorption of the halide ion Br-which facilitates the physical adsorption of the CP+ which is commenced by chemisorption of the pyridinium ring via its p-electrons with the surface Fe atom. Polarization curves and Weight loss measurements confirm the protection efficiency trends for the three surfactants.