Egypt. J. Chem. Vol. 62, No. 10, pp. 1879 - 1894 (2019) 144 Calicotome Extract as a Friendly Corrosion Inhibitor of Carbon Steel in Polluted NaCl (3.5% NaCl + 16 ppm Na 2 S): Chemical and Electrochemical Studies A.S. Fouda 1* , H.M. Killa 2 , A. Farouk 2 , A.M. Salem 2 1 Chemistry Department, Faculty of Science, Mansoura University, Mansoura-35516, Egypt. 2 Chemistry Department, Faculty of Science, Zagazig University, Zagazig, Egypt. Egyptian Journal of Chemistry http://ejchem.journals.ekb.eg/ *Corresponding author e-mail: asfouda@hotmail.com, Fax: +2 050 2202271, Tel: +2 050 2365730 Received 17/2/2019; Accepted 13/4/2019 DOI: 10.21608/ejchem.2019.7656.1649 © 2019 National Information and Documentation Center (NIDOC) T HIS study describes the ability of Calicotome extract (CE) to inhibit the corrosion of C-steel in polluted NaCl (3.5%NaCl+ 16 ppm Na 2 S) solution which carried out using chemical (weight loss, WL)and electrochemical(potentiodynamic polarization, PP, electrochemical impedance spectroscopy, EIS and electrochemical frequency modulation, EFM) techniques. Langmiur isotherm was tested to describe the adsorption behavior of C-steel surface. The PP measurements revealed that the adsorption of extract affects both anodic and cathodic reactions. The protection effciency (% IE) increases by rising concentrations, while it lowers with raising the temperature. The C-steel surface morphology in the presence and absence of CE has been tested via Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and (FTIR) spectroscopy measurements. The obtained data from different techniques are in good agreement. Graphical Abstract Keywords: Corrosion, Calicotome extract (CE); C-steel, SEM; AFM and FTIR. -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 1E-8 1E-7 1E-6 1E-5 1E-4 0.001 0.01 Blank 50 ppm 100 ppm 150 ppm 200 ppm 250 ppm 300 ppm log i , mA cm -2 E, V vs SCE