Journal of Chemical and Pharmaceutical Research (ISSN : 0975-7384)

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Original Articles: 2015 Vol: 7 Issue: 5

Corrosion inhibition of environmental friendly inhibitor using Theobromab cacao peels extract on mild steel in NaCl solution

Abstract

The effects of Theobroma cacao peels extract (TCPE) on corrosion inhibition of a 0.32%C mild steel in 1.5M NaCl solution was studied using weight loss at various temperature, and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods at room temperature and elevated temperature. Electrochemical polarization was conducted to evaluate the type of inhibition. Infrared spectra and phytochemicals test were performed to determine the chemicals constituent in the extract of cacao peels that play a role in the inhibition process. Sample surface morphology was observed by using a scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Experimental results revealed that the corrosion rate decreases with increasing extract concentration, but it increases with increasing temperature. The maximum corrosion inhibition efficiency is relatively high, that is 91.93% (weight loss), 85.90% (Tafel), 90.19% (Rp) and 75.23% (EIS) at a concentration of 2.5% the extract. The increasing of inhibition efficiency is due to the increase of charge resistance transfer (Rct) as a result of chemical adsorption in the surface. Chemical adsorption occurs on the surfaces obeys Langmuir isotherm adsorption, with an indication of adsorption unimoleculer. The polarization curve shows the inhibitor behaves as a mixed inhibitor with the dominant cathodic inhibition. The use of polar extract of Theobroma cacao peels as inhibitor is quite effective in reducing corrosion attack of NaCl solution on the mild steel.