The Use of Some Natural Extracts as Environmentally Friendly Carbon Steel Corrosion Inhibitors

This paper presents the influence of natural extracts obtained from Levisticum officinale and Citrus x clementine on the corrosion of carbon steel in a 3.5% NaCl solution. We started from dried leaves of Levisticum officinale and Citrus x clementine peel in order to prepare several extracts in a 50%:50% (v:v) water/ethanol solution and in analytical-grade ethanol. Several electrochemical techniques, such as open circuit potential monitoring, electrochemical impedance spectroscopy and potentiodynamic polarization, were employed in order to investigate the influence of the synthetized extracts on the corrosion of carbon steel. The aggressive solution that the corrosion tests were performed in was a 3.5% NaCl solution modified with different amounts of the extracts. The electrochemical tests performed in order to determine the influence of the Levisticum officinale leaf and Citrus x clementine peel extracts showed that these extracts may be employed as natural corrosion inhibitors for carbon steel in a 3.5% NaCl solution, achieving inhibiting efficiencies up to 87.8%, in the case of the Levisticum officinale extracts.