Pepper extract effectiveness as a natural inhibitor against corrosion of steel samples (SS) in 1 M hydrochloric acid; Theoretical (DFT calculation – MD simulation), thermodynamic, and electrochemical-surface studies

Abstract

Recently, researchers have tried to find potential approaches for mitigating the metals' corrosion rate in aggressive environments. In the present study, the exploration of the Pepper extract's impact on the steel samples (SS) dissolution rate reduction in HCl media was done. The extract ingredients were detected by Raman, UV-Vis, and FT-IR approaches. The Pepper extract mechanism and effectiveness in corrosion mitigation were examined by polarization approach and EIS exam. Adsorption of the inhibitive components in the Pepper extract over a steel surface was theoretically studied by DFT calculation and MD simulation. Around 92% efficiency with mixed protection activity was recorded after 6 h of sample exposure to the 800 ppm Pepper extract-included solution at ambient temperature. The FE-SEM and AFM records confirmed the considerable surface degradation reduction on the Pepper extract-containing HCl solution-attacked samples. The weight loss test results have reflected 91% efficiency at 800 ppm and ambient temperature. However, by raising the harsh media temperature up to 55 ºC the anti-corrosion index was reduced 90%. The thermodynamic computation proved the exothermic adsorption of the molecules according to the Langmuir-type isotherm proving the monolayer Pepper extract molecules' interaction with the iron surface. • The Pepper extract's impact on the steel dissolution rate reduction in HCl media was studied. • Adsorption of the inhibitive components in Pepper extract over steel surface was theoretically studied. • Around 92% efficiency with mixed protection activity was recorded after 6 h sample exposure to the 800 ppm Pepper extract.