Study of Corrosion Inhibition of Mild Steel in 1 M HCL Solution using KI Solution as an Inorganic Inhibitor

Abstract

The inhibitory effect of potassium iodide at concentrations of (0, 0.5, 1, 1.5, 2, and 2.5) ml/L in corroding mild steel by corrosive solution (1 M HCl) was studied using the method of weight-loss at different temperatures of (303, 313, 323, and 333) K. The result showed that potassium iodide acts well as an inhibitor where the inhibitory efficiency (%IE) reached 94% at the highest temperature (333) and the highest concentration (2.5) ml/L. The adsorption process was obeyed by the Langmuir isotherm model and didn't follow the Freundlich isotherm model. The thermodynamic parameters were studied, and it was found that they support that the adsorption process was spontaneous and endothermic. Mixed physical and chemical adsorption was indicated by ( ) values in the range of -20 to -40 kJ/mol. The electronic scanning microscope (SEM) was used to evaluate the surface morphology, which confirmed its results in the occurrence of the adsorption process.