Electrochemical Assessment of Rhus typhina L. Leaf Extract as a Novel Green Corrosion Inhibitor for OL37 in 1 M HCl Medium

This study evaluates the corrosion-inhibiting effects of the methanolic (P₁) and the hydroalcoholic (P₂) extracts of the <i>Rhus typhina</i> L. leaves on carbon steel (OL37) in 1 M HCl. Extracts were prepared with microwave-assisted extraction and characterized using HPLC and LC-MS. Electrochemical methods (OCP, EIS, PDP) and surface analyses (SEM, EDX) assessed the performance of both extracts. The results showed that the P₁ and P₂ extracts significantly reduced corrosion rates by forming protective layers on the metal surface, with inhibition efficiencies exceeding 90%, at 1000 ppm concentration, for P₁ (93%), for P₂ at 800 ppm (91%) and 1000 ppm (94%). The P₂ extract demonstrated superior long-term performance, maintaining protection after 96 h of immersion. The extracts function as mixed-type inhibitors, affecting both anodic and cathodic reactions, with physicochemical adsorption demonstrated by the Langmuir isotherm. Overall, the <i>Rhus typhina</i> leaf extracts, particularly the P₂ extract, offer a promising, eco-friendly approach to corrosion prevention in acidic environments.