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The chemical composition of Jatropha curcas seeds oil was determined using chromatography gas (GC/MS) analysis after the esterification of fatty acids to methyl ester (FAME). The obtained results show that the average yield of Jatropha curcas seeds oil reached a maximum value of 50%. The seeds oil fatty acids carbon chain was composed of palmitic, oleic and linoleic acids. The percentage of unsaturated fatty acids reached a value of 77%.The new developed formulation containing Jatropha curcas seeds oil (labeled as JAC) was tested as a friendly iron corrosion inhibitor in an acidic medium by potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) techniques. The surface analysis was performed using Scanning Electron Microscopy (SEM). The electrochemical measurements show that the JAC formulation is a mixed type inhibitor. The obtained inhibition efficiency results increase with higher inhibitor concentrations, to attain a maximum value of 97% at 250 ppm. Furthermore, the protective effect is reinforced by increasing the immersion time and the rotation speed of the working electrode.

This study examines the development of a new green and eco-friendly formulation derived from Opuntia dillenii seed oil (labeled as FOD) and its application as a corrosion inhibitor to protect iron which is subject to corrosion phenomena that become important especially in acidic environments as acid rain. Physicochemical properties and fatty acid analysis of Opuntia dillenii seed oil were performed and they demonstrated that the oil is a major source of unsaturated fatty acids, in particular linoleic acid, with a percentage of 73.388%. Corrosion inhibition effect of FOD was studied by gravimetric methods, electrochemical measurements, and scanning electron microscopy coupled with elemental analysis (SEM/EDX). Obtained results confirmed that FOD behaves as a good mixed corrosion inhibitor with predominant anodic activity. Inhibition efficiency of FOD is more important when the concentration of FOD and the immersion time increase, reaching values up to 99%. FOD forms a barrier layer on the surface of the iron, and thereby minimizes the contact area between the metal surface and the corrosive solution. The adsorption behavior of FOD on iron surface obeys Langmuir adsorption isotherm with chemisorption and physisorption mechanism.

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The corrosion of iron in an acidic medium similar to acid rainwater (pH = 3.6) at various rotation speeds was investigated. The investigation included the inhibiting effect of two new green formulations containing oils extracted from the seeds of Jatropha curcas (labeled JAC) and Aleurite moluccana (labeled ALM). The inhibition efficiency was evaluated using electrochemical measurements, after performing an automatic ohmic drop compensation (ZIR). The results obtained show that an increase in the rotation speed leads an increase in the current density (from 75.57 µA/cm2 at 0 rpm to 99.09 µA/cm2 at 1500 rpm). This increase can be explained by the increase in the amount of dissolved oxygen at the electrode surface in the acidic rain solution (pH = 3.6). Also, the two environment-friendly corrosion inhibitors both act as mixed type inhibitors that protect iron against corrosion in the acidic solution. The inhibition efficiency increases with an increase in the inhibitor concentration to attain a maximum of 97% and 96% at 250 ppm of the ALM and the JAC, respectively.