Evaluation of Schiff Base Containing Three C=N Groups as a Corrosion Inhibitor for ۱۰۱۸ Carbon Steel in ۱.۰ Molar Hydrochloric Acid Media

In this study, the inhibition effect of a Schiff base with three C=N groups and three aromatic rings on corrosion of ۱۰۱۸ carbon steel in ۰.۱ M hydrochloric acid is investigated by two electrochemical methods, impedance spectroscopy and polarization, at ۲۵ °C. The inhibition efficiency increases by increasing the concentration of Schiff base from ۱۰۰ to ۵۰۰ ppm and the highest inhibition efficiency was about ۹۶% at ۲۵ °C for the concentration of ۵۰۰ ppm of Schiff base. The results of the polarization method showed that the Schiff base in acidic solution acts as a mixed inhibitor. The charge transfer resistance (Rct) for ۱.۰ M HCl solution increases from ۳۹.۵ Ω.cm۲ to ۹۴۹.۷ Ω.cm۲ by adding ۵۰۰ ppm of Schiff base. The effect of temperature on the inhibitor performance is investigated by electrochemical polarization method in the range of ۲۵-۶۵ °C and it shows decreasing of inhibition efficiency with increasing temperature. The adsorption of Schiff base molecules on the surface of ۱۰۱۸ carbon steel at all temperatures follows the Langmuir adsorption isotherm. The values of ΔGads obtain -۳۲.۱۲۲ kJ and -۳۵.۱۲۴ kJ mol-۱ at ۲۵ °C and ۶۵ °C, respectively, which shows increment in its absolute value. These results show that the adsorption of Schiff base molecules on the surface of ۱۰۱۸ carbon steel is a physico-chemical adsorption.

Keywords:

Corrosion inhibitor , Schiff base , ۱۰۱۸ carbon steel , Hydrochloric acid , Polarization , Electrochemical impedance spectroscopy. , بازدارنده ی خوردگی , باز شیف , کربن استیل ۱۰۱۸ , هیدروکلریک اسید , پلاریزاسیون , طیف سنجی امپدانس الکتروشیمیایی