Investigation of adsorption and inhibitive effect of phosphite on corrosion of mild steel in hydrochloric acid media

L. Herrag¹, B. El Bali², M. Lachkar³ and B. Hammouti¹*

¹Laboratoire de Chimie Appliquée et Environnement, Faculté des Sciences BP.717, 60000 Oujda (Morocco). ²Laboratoire du Chimie Solide Minéral, Faculté des Sciences BP.717, 60000 Oujda (Morocco). ³Laboratoire du Chimie Organique, Faculté des Sciences, 1796 Atlas, DEM Fes (Morocco).

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ABSTRACT:

The inhibition behaviour of a phosphite compound: NaMg(H2PO3)3 .H2 O (abbr. PhMg) on C38 steel in 1 M HCl solutions was investigated at 25 °C using electrochemical and weight loss methods. The results indicated that the title compound inhibited the corrosion of steel and the extent of inhibition increased with its concentrations. A mixed-inhibition mechanism is proposed for the inhibitive effect of PhMg. Effect of temperature is investigated in the (313-353 K) range. The determination of activation and adsorption parameters indicated that the inhibition action in the presence of PhMg is due to physical adsorption.

KEYWORDS:

Corrosion; Mild steel; Corrosion inhibitors; Acid; phosphite