Abstract
The inhibiting action of nonionic surfactants, namely, propoxylated fatty esters (PFE) with different number of propylene oxide toward the corrosion of Zn in 0.1 M HCl solutions was investigated. Four techniques were used in this study such as weight loss, galvanostatic polarization, potentiodynamic anodic polarization and electrochemical impedance spectroscopy. The inhibition efficiency of PFE compounds increases by increasing the concentrations of PFE, number of propylene oxide unit and with lowering temperature. The inhibition was interpreted by adsorption of PFE molecules on the Zn surface according Temkin's isotherm. Galvanstatic polarization indicated that the PFE acts as a mixed type inhibitor. PFE molecules inhibit the pitting corrosion of Zn in a solution containing Cl- ions by moving the pitting potentials into a more noble direction. The activation thermodynamic parameters such as E-a*, Delta H* and Delta S* are calculated and explained.