K. Hema, B. R. Venkatraman and A. Subramania
The inhibitive action of the Ziziphus jujubaleaves (ZJL) extract against corrosion of carbon steel in 1N HCl was investigated using weight loss measurements, gasometric method, potentiodynamic polarization curves and electrochemical impedance spectroscopy methods. The results obtained from these methods indicate that the extracts perform as a good green corrosion inhibitor in acidic medium and inhibition efficiency increased with extracts concentration. The maximum inhibition efficiency of 82.2% was obtained at the best concentration of 800 ppm of ZJL extract. The effects of temperature and immersion time on carbon steel in 1N HCl were also studied. Polarization curves show that ZJL extract act as a mixed-type inhibitor in hydrochloric acid. EIS shows that the capacitance of double layer decreases and charge-transfer resistance increase with the optimum concentration of 800 ppm of ZJL extract, confirming the adsorption process mechanism. The adsorption of ZJL extract on the surface of the carbon steel follows the Langmuir adsorption isotherm. The mechanism of inhibition was confirmed by kinetic and thermodynamic parameters obtained from 303K to 363K temperatures using weight loss method. The metallurgical microscope results established the formation of a protective layer on the carbon steel surface.