Performances of plant based corrosion inhibitors in controlling corrosion of mild steel in sodium chloride environment

Abstract

Addition of corrosion inhibitors is one of the most commonly used corrosion control method in current industries. However, most of corrosion inhibitors available on the market are inorganic and toxic which pose threat to the environment when they are discharged. Thus, green corrosion inhibitors that are non-toxic, renewable, cheaper and environmentally friendly are required to mitigate this issue. One of the viable sources of green corrosion inhibitors is by using plant extracts. The present study focused on the application of green corrosion inhibitors using Jatropha curcas and Hibiscus sabdariffa (Roselle) extracts in controlling corrosion of mild steel in 3.5% NaCl environment. Results of immersion test showed that Jatropha extract recorded highest inhibition efficiency at 90.84% while Roselle extract attained highest inhibition efficiency at 77.35% in NaCl environment. Potentiodynamic polarization test performed signify that both extracts were mixed-type inhibitors. The presence of adsorptive protective films formed on the surface of mild steel sample were proven through electrochemical impedance spectroscopy (EIS) analysis. Results of potentiodynamic polarization test and EIS analysis were in agreement with results of immersion test. Tests performed indicate that both Jatropha and Roselle have high inhibitive performances in 3.5% NaCl environment with Jatropha extract performing slightly better than Roselle extract. Further studies on type of adsorption as well as determination and quantification of phytochemical compounds affecting inhibition performances should be done to further understand and improve the inhibition performances of the extracts.