Effect of benzamide on the corrosion inhibition of mild steel in sulphuric acid

The effect of benzamide as a chemical inhibitor on mild steel corrosion in 0.5M H 2 SO 4 was studied at ambient temperature. The experimental work was performed with gravimetric and potentiostatic polarization measurement methods. Potentiostatic polarization measurement was performed with a potentiostat (Autolab PGSTAT 30 ECO CHIMIE) interfaced with a computer for data acquisition and analysis. The benzamide inhibitor achieved very effective corrosion inhibition of the steel specimens in the H 2 SO 4 test medium. The inhibition performance increased with increasing concentration of the inhibitor. Benzamide's best performance was achieved with the 4 g 200 mL -1 H 2 SO 4 concentration and closely followed by the 3 g 200 mL -1 of the H 2 SO 4 . In 0.5 M H 2 SO 4 , the 4 g and 3 g 200 mL -1 H 2 SO 4 gave the optimal performance with weight loss of 2.99 g at 480 h of the experiment, respectively. The corrosion rate for 4 g's was 6.4 mm yr -1 . The experiment also achieved polarization resistance values of 3.98 and 2.37E + 01 ; corrosion rate, CR, of 7.48E + 00 and 1.26E + 01 mm yr -1 and current density (Icorr) values of 6.45E-04 and 1.08E -03 A cm -2 , respectively. The corrosion inhibition efficiency values are, respectively, 60 and 70 % for both 3 g and 4 g 200 mL -1 H 2 SO 4 concentrations at 48 h. Results of ba and bc indicated a mixed type inhibitor. Benzamide adsorption on the steel's surface obeys the Freundlich adsorption isotherm.