Nonlinear dynamics of ascorbic acid-KI interaction on carbon steel corrosion in acid medium

Ascorbic acid (AA) has been reported as a corrosion inhibitor of carbon steel. The combined effect of AA and potassium iodide (KI) in the dynamics of the corrosion process of 1018 carbon steel is studied by electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) in an acid medium. EN data were used for nonlinear analysis by means of recurrence plots and their corresponding parameters, as well as by delay maps. Important information about the corrosion process of carbon steel corrosion in the presence of these two substances was obtained. AA does not behave as an inhibitor in this system, but the influence of KI is significant in inhibitor efficiency. The dynamics is established mainly by the adsorption of the I- ions on the steel surface and confirmed by the information entropy. The action of AA is to increase the degree of chaos when concentration increases. A relevant aspect determined is the relationship between the nonlinear dynamics of a corrosion process and its intensity.