Abstract

Yuli Yetriand Sukatik

DOI : http://dx.doi.org/10.13005/ojc/330456

Corrosion inhibition and adsorption properties of the crude extract and polar extract of Theobroma cacao peels on mild steel in HCl 1.5M was studied using the method of weight lost and potentiodynamic polarization (Tafel). Inhibition efficiency were measured for immersion for 192 hours, the concentration of the extract 0.5-2.5% with an interval of 0.5% and the rang of temperature (303- 323) K. Electrochemical polarization evaluated to know the type of inhibitor. Infrared spectra and GCMS were conducted to determine the extract compounds that act in the inhibition process. The surface morphology of samples was observed by a photo optical. The results showed that the corrosion rate decreases with   increasing the concentration of the extract and increases with increasing temperature. Inhibition efficiency for crude extract and polar extract was 83.45%and 96.26% (weight loss), 85.23% and92.08% (Tafel) and 72.29%and 83.95% (303 K) at 2.5% of concentration of extract. The increase in the efficiency of inhibition was also followed by an increase in the degree of surface coverage of a chemical adsorption is happening on the surface. Adsorption that occurred on the surface of mild steel obeys the Langmuir isotherm. This polarization curve indicates inhibitor behaves as mixture inhibitor with predominantly on cathodic inhibition. Apparently, the polar extract is more effective to reduce the corrosion rate than crude extract. The addition of polar extract of cacao into a solution of HCl is very effective to reduce the attack corrosion of the mild steel surface.

Cacao peels extract; Corrosion inhibitor; Tafel; Adsorption; GCMS

[ View HTML Full Text]