Abstract

LOTO, Cleophas A.; LOTO, Roland T.  and  JOSEPH, Olufunmilayo O.. Effect of benzamide on the corrosion inhibition of mild steel in sulphuric acid. S.Afr.j.chem. (Online) [online]. 2017, vol.70, pp.38-43. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2017/v70a6.

The effect of benzamide as a chemical inhibitor on mild steel corrosion in 0.5M H₂SO₄ 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 H₂SO₄ 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 H₂SO₄ concentration and closely followed by the 3 g 200 mL^-1 of the H₂SO₄.In 0.5 M H₂SO₄, the 4 g and 3 g 200 mL^-1 H₂SO₄ 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 + 01Ω; corrosion rate, CR, of 7.48E + 00and1.26E + 01 mm yr¹ 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 H₂SO₄ 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.

Keywords : Electrochemical corrosion; benzamide; inhibitor; sulphuric acid; mild steel; polarization.

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