Corrosion inhibition of 6063 aluminum alloy by Coriandrum sativum L seed extract in phosphoric acid medium

Coriandrum sativum L. seed extract (CSE) was used as a green inhibitor for corrosion control of 6063 aluminium alloy in 1 M phosphoric acid using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques at the temperature range of 30°C to 50°C. Surface morphology of the metal was studied using Scanning electron microscopy (SEM), both in the absence and in the presence of inhibitor. Inhibition efficiency increased with extract concentration and decreased with temperature. Inhibitor acted as mixed type of inhibitor. The adsorption of CSE on alloy surface was fit into Langmuir adsorption isotherm. Kinetic and thermodynamic parameters governing the adsorption process were calculated and discussed in detail. Results obtained by Tafel polarisation method and electrochemical impedance spectroscopy method were in good agreement with one another. SEM studies confirmed the corrosion inhibition of the alloy due to the adsorption of CSE. CSE emerged as a biodegradable, environmentally benign green inhibitor with minimal health and safety concerns. It has the potential to be a cost effective alternative to synthetic corrosion inhibitors. It can be treated as effective tool to preserve environmental burden of harmful synthetic organic inhibitor.