Green-based corrosion protection for mild steel in 3.5 % NaCl and distilled water medias: Jatropha curcas and Roselle extracts

Abstract

In this study, the natural sources of Jatropha curcas and Hibiscus Sabdariffa calynx (Roselle) extracts as green corrosion inhibitors were employed to improve the corrosion resistance of mild steel in simulated (3.5% NaCl) and distilled water medias. The inhibiting performance of two types of extracts was studied by visual inspection, microscope analysis, and various electrochemical measurements and the data of corrosion rate were statistically analyzed. The main phenolic compounds of Jatropha and Roselle extracts were confirmed via a liquid chromatography-mass spectrometry. Meanwhile, the functional groups of active phytochemical compounds were characterized via attenuated total reflection spectroscopy (ATR). The results of different electrochemical tests were revealed that the additions of Jatropha and Roselle extracts into the corrosion solution have an efficient corrosion inhibitor in reducing the corrosion rate though forming an adsorptive protective film on the surface, which reduced contact between samples’ surfaces and solution medium and ultimately reduced corrosion attack. Practically, Jatropha extract showed the highest inhibitive efficiencies compared to Roselle extract in both simulated water and 3.5% NaCl solutions.