Mild Steel Corrosion Inhibition, in 4 N Sulphuric Acid, by a Green Inhibitor

Abstract

Use of Amaranthus extract, as mild steel corrosion inhibitor, in a p ickling paste with H2SO4, has been investigated. The electrochemical experim ents were conducted to bring forth results regarding various parameters, viz., c orrosion current, anodic polarization and cathodic polarization. The corrosion current gr adually decreased with time, for both uninhibited and inhibited systems. Polarization cur ves values indicate that Amaranthus extract adsorption modified anodic dissolution mech anism, as well as cathodic hydrogen evolution. From the results, it is clear t hat both cathodic and anodic reactions were inhibited, and that inhibition increased as th e inhibitor concentration increased in acidic media, but the cathode was more polarized. T his result indicated that Amaranthus extract can be classified as a cathodic inhibitor, in a 4 N H2SO4 solution. Surface analysis via scanning electron microscope (SEM) sho wed a significant improvement on the mild steel plate surface morphology, in the pre sence of optimum inhibitor concentrations. Thus, by conducting these experimen ts, our aim is to use inhibited pickling acid in the paste form, so that it can be conveniently applied on large structures, as well as on small tools, to be pickle d/c aned. As a contribution to the current interest on environmentally friendly green corrosion inhibitors, the present study investigates the inhibiting effect of Amaranthus extract, a green inhibitor which is commonly known as Pigweed.