Abstract
The corrosion inhibition of mild steel by Catharanthus roseus (Vince rosea) and Turmeric (Curcuma longa) extracts as green inhibitors in 1 M HCl solutions has been investigated by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), hydrogen evolution measurements and scanning electron microscope (SEM) techniques. Results obtained show that these investigated compounds are good inhibitors and act as mixed type inhibitors. The inhibition efficiencies increase with increasing inhibitor concentration. The SEM results show the formation of protective film on the mild steel surface in the presence of Catharanthus roseus and Turmeric extracts. The results obtained from different tested techniques are in good agreement.
Highlights
Iron and its alloys are widely used in many applications, which have resulted in research into the corrosion resistance in various aggressive environments [1]
It could be conducted that these inhibitors are mixed-type for mild steel in 1M HCl medium, which may be adsorbed on the cathodic sites of mild steel and reduce the evolution of hydrogen
2) The corrosion current density decreases with increasing the concentration of plant extract, which indicates that the presence of these extracts retard the dissolution of mild steel in 1M HCl solution and the degree of inhibition depends on the concentration and type of the inhibitor present
Summary
Iron and its alloys are widely used in many applications, which have resulted in research into the corrosion resistance in various aggressive environments [1]. The development of corrosion inhibitors is based on organic compounds containing N, O, S atoms and multiple bonds in the molecules that facilitate adsorption on the metal surface [10]. The inhibition performance of plant extract is normally ascribed to the presence of complex organic species, including tannins, alkaloids and nitrogen bases, carbohydrates and proteins as well as hydrolysis products in their composition. These organic compounds usually contain polar functions with nitrogen, sulfur, or oxygen atoms and have triple or conjugated double bonds or aromatic rings in their molecular structure, which are the major adsorption centers [15]. The concentration range of inhibitor was 50 to 300 ppm
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