Red pepper extract as eco-friendly corrosion inhibitor for Carbon steel N80 in 1 M HCl: Electrochemical and surface morphological studies

Abstract

Four different concentrations of a plant inhibitor (dry red pepper) were created to investigate its effectiveness in preventing corrosion of a N80 carbon steel alloy used in petroleum pipe manufacturing. This was done in a 1M HCl acidic solution at various temperatures using electrochemical techniques and surface analysis. The inhibitor was discovered to be effective and efficient. As inhibitor concentrations rise, inhibition also increases because the protective layer becomes thicker. At a concentration of 200 ppm at a temperature of 298 K, the inhibition efficiency reached 92.69%. Corrosion rate decreases in the presence of the plant inhibitor. Despite the presence of the plant inhibitor, the corrosion rate in the acidic media (HCl 1M) was 15.58 mpy lower than when the inhibitor was absent. It reached 1.138 when it was. This is because of the reduction in the current density of Icorr. The polarisation results showed that the addition of the inhibitor reduced the corrosion current density of the steel. The Carbon N80 corrosion rate ranges from 34.22 µA/cm2 for the sample without inhibitor to 2.5 µA/cm2 for the sample including 200 ppm of inhibitor (C). The polarisation curves and electrochemical investigations suggest that the corrosion inhibitor exhibits both anodic and cathodic inhibition processes, indicating a mixed kind of inhibition. FT-IR technology analysed the inhibitor's chemical composition and revealed the presence of functional groups and heteroatoms. SEM was utilised to locate the inhibitor layer on the carbon steel alloy surface, which serves to prevent corrosion