The Use of papaver somniferum L. Plant Extract as Corrosion Inhibitor

Abstract

The corrosion inhibition and adsorption characteristics of the extract obtained from the plant Papaver somniferum L. (PSL) by electrochemical methods at different temperatures (25, 35 and 45°C) were investigated in 0.2 M HCl and 0.2 M HCl + x ppm PSL solutions on AISI 304 stainles steel (AISI 304 SS), ETIAL 150 aluminum alloy (ETIAL 150 Al) and copper. The best inhibition was obtained containing 0.2 M HCl + 500 ppm PSL inhibitor concentration solutions. Surface observations of metals after standing experiments were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy scattering X-ray method EDX). The inhibition effect was increased with an increase in inhibitor concentration. Extract adsorbed on the surface of metals obeyed the Langmuir adsorption isotherm. The Langmuir adsorption isotherms confirm the physical adsorption mechanism and the inhibitor is a mixed type inhibitor. SEM images show cracks and pits on the surfaces in extract free solutions. AFM and SEM were showed thick dense film on metal surfaces in containing extract solutions. The occuring film closed all the active corrosion sites on metals and inhibited corrosion mechanism. Some thermodynamic and kinetic parameters for the adsorption process, that were adsorption equilibrium constant (K_ads), Gibbs adsorption free energy (G_ads), and activation energy of corrosion reaction (E_a), were calculated and discussed by using Tafel results. Arrhenius energies increased with an increase in inhibitor concentration. Activation energies and Gibbs free energies for the inhibition reactions were supported the physical adsorption mechanism.