Adsorption and Corrosion Inhibition Behavior of Polyethylene Glycol and Surfactants Additives on Mild Steel in H2SO4

The adsorption and corrosion inhibition behaviors of polyethylene glycol (PEG) alone and in the presence of surfactants sodium dodecyl benzene sulfonate and cetyltrimethyl ammonium bromide on mild steel in 0.1 M H₂SO₄ in temperature range of 30-60 °C was investigated using weight loss method, solvent analysis of iron ions, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), atomic force microscopy (AFM) and determination of kinetic/thermodynamic parameters. The inhibition efficiency (IE) of PEG increased with increasing concentration showing a maximum IE of 86.91% at 30 °C at 25 ppm but decreased with increasing temperature. Inhibiting action of PEG is synergistically enhanced on addition of small amount of surfactants. Surface morphology of the corroded mild steel specimen as evaluated by SEM, EDAX and AFM confirmed the existence of an adsorbed protective film on the mild steel surface. The calculated thermodynamic/kinetic parameters reveal that adsorption process is spontaneous and obey Langmuir adsorption isotherm.