Synergistic Inhibition Effect Between Capsella bursa-pastoris Extracts and Iodide Ions for Q235 Mild Steel in 1 M HCl Solution

The inhibition effect of Capsella bursa-pastoris extracts (CBE) and its synergistic effect with KI (CBEK) for Q235 mild steel in 1 M HCl solution were studied by electrochemical measurements. Both CBE and CBEK can serve as eco-friendly, mixed-type inhibitors, and the inhibition efficiency increases with the concentration and temperature. The synergistic parameter (SI) indicates a cooperative mechanism between the iodide anions and CBE molecules at lower temperature. The associated thermodynamic and kinetic data suggest the presence of CBEK on metal surface mainly through chemisorption at higher temperature. The adsorption processes follow Langmuir isotherm.