Study of the effect of temperature and time on the anticorrosive power of a Schiff base molecule named {4, 4’ Bis (2-Furane Carboxaldehyde) Diimino Diphenyl Sulfide} on mild steel in acidic medium.

Inhibitory effect of a Schiff base molecule {4, 4’ Bis (2-Furane carboxaldehyde) diimino diphenyl sulfide} on corrosion of mild steel in 1M HCl solution has been studied using weight loss measurements and polarization curves methods. The results of the investigation show that the studied compound with mean efficiency of 92% at 5.10 -3 M additive concentration have fairly good inhibiting properties for mild steel corrosion in hydrochloric acid, and it is as mixed inhibitor. All measurements show that inhibition efficiency increase with increase in inhibitor concentration. This reveals that inhibitive action of inhibitor were mainly due to adsorption on mild steel surface. Analysis of the temperature dependence of inhibition efficiency as well as comparison of corrosion activation energies in the absence and presence of inhibitor gives some insights into the possible mechanism of inhibitor adsorption [1]. In order to evaluate the adsorption of inhibitor and to calculate thermodynamic and activation parameters of the corrosion processes of steel in acidic media, the effect of temperature on the polarization curves and corrosion parameters (E corr (vs. SCE), I corr , ba, bc, IE% and q) in the absence and presence of various concentrations of inhibitors were studied. Activation parameters of the corrosion process such as activation energies, E a , activation enthalpies, ∆H° a , and activation entropies, ∆S° a , were calculated by the obtained corrosion currents at different temperatures (25-35-45 and 55°C). The results obtained from the polarization curves show an increase in the current density with increasing temperature followed by an increase in the inhibitory efficiency at 35 °C. Beyond this temperature the inhibitory efficiency begins to decrease with the increasing temperature with analogous increase in corrosion activation energy in the presence of inhibitor compared to its absence The time effect on inhibitory efficiency was studied using gravimetric measurements for different times (8h, 16h, 24h, 48h and 72h). The results also indicated that the inhibitory effiaciency increased with immersion time to 94% at 72 hours and that the studied shiff base compound retarded the corrosion of mild steel in the 1 M HCl medium. Keywords: Corrosion, mild steel, HCl, Schiff base, inhibitory efficiency. References [1] D. Daoud, T. Douadi, H. Hamani, S. Chafaa and M. Al-Noaimi (2014). Corrosion inhibition of mild steel by two new S-heterocyclic compounds in 1 M HCl: Experimental and computational study. Corrosion Science 79, 50–58.