Coriandrum sativum L.—A novel green inhibitor for the corrosion inhibition of aluminium in 1.0 M phosphoric acid solution

The corrosion inhibition characteristics of aqueous extract of seeds of Coriandrum sativum L. (CSE) have been studied as an eco-friendly green inhibitor for corrosion control of aluminium in 1.0 M phosphoric acid solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The effects of inhibitor concentration and temperature on the inhibition action were investigated. The adsorption of CSE on metal surface obeyed Langmuir adsorption isotherm. Polarization measurements showed that the CSE acted as mixed inhibitor in 0.5 M and 2.0 M phosphoric acid solution and the inhibitor molecules followed physical adsorption on the surface of aluminium. The surface morphology of aluminium, in the absence and presence of CSE in 1.0 M phosphoric acid solution, was studied using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results obtained from Tafel extrapolation and A.C electrochemical impedance spectroscopy (EIS) techniques were in good agreement.