Adsorption and Computational Studies for Evaluating the Behavior of Silicon Based Compounds as Novel Corrosion Inhibitors of Carbon Steel Surfaces in Acidic Media

Two organo-silicon compounds namely; di-triethanolamine siloxane and bis (dithioamine triethanolamine) siloxane were employed as inhibitors for C-steel alloys corrosion in 1 M H2SO4 solution utilizing potentiodynamic polarization, electrochemical impedance and computational studies. According to both polarization and impedance data, it has been found that the investigated organosilicon compounds work as efficient corrosion inhibitors and the protection aptitude raised by increasing the inhibitor concentration. The shown behavior of the tested compounds is cathodic and anodic type inhibition following Langmuir's adsorption isotherm. The evaluated adsorption parameters, adsorption equilibrium constant (K-ads) and Gibbs free energy of adsorption ads (Delta G(ads)(o)) reveal a good association between the inhibitor molecules and the surface of carbon steel in a predominantly chemisorptions manner. In the view of computational quantum and molecular dynamic simulation studies, molecular structure effectiveness and suggested mechanism of protection efficiency were discussed. Surface characterization studies such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) have been utilized as corroborative tools for confirming the presence of the defensive inhibitor film on the surface of a metal.