Corrosion inhibition performance of low cost and eco-friendly Treculia africana leaves extract on aluminium alloy AA7075-T7351 in 2.86% NaCl solutions
Solomon C. Udensi, O. E. Ekpe, Lebe A. Nnanna
Abstract
The viability of using a biologically active and biodegradable extract from Treculia africana (TA) leaves, for green corrosion inhibition, for AA7075-T7351 aluminium alloy, in 2.86% NaCl solutions was assessed via Tafel polarization (TP), electrochemical impedance spectroscopy (EIS), thermodynamic, and weight loss (WL) techniques at temperatures (θ); 298, 313, 323, 333, and 338oK. EIS, TP and WL results showed comparable inhibition efficiencies (ξs) of TA. Increases in TA concentration and θ of the environment led to increase and decrease of ξ respectively. The inhibiting episode of TA on AA7075-T7351, was dominated by anodic processes, easily attached adsorbates, endothermic, strong and spontaneous reactions which fitted well to Langmuir, Freundlich and Temkin models. Bode plots showed phase angles and slopes that increased with increases in TA concentration. Scanning electron microscope (SEM) results confirmed the inhibiting property of TA extract from the increasing AA7075-T7351 surface smoothness obtained with successive increases in TA concentration.