Adsorption corrosion inhibitive behavior of peels extract of theobroma cacao on mild steel as a corrosion inhibitor in HCL media

Abstract

Theobroma cacao peels extract (TCPE) obtained from the result of the maceration of cacao peels with methanol. TCPE contains an organic compound that can be used as a corrosion inhibitor. This compound has an advantage in being non-toxic and biodegradable. The essential compound of TCPE was analyzed by using Gas Chromatography-Mass Spectra (GC-MS) before fractions. This essential compound was characterized to obtain a high content of oxygen which leads to its capability to control the corrosion. Corrosion properties of mild steel in hydrochloric acid (HCl) solution by the use of TCPE were determined by conducting Electron Impedance Spectroscopy (EIS) method. Surface analysis by Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM-EDX), X-ray Photon Spectroscopy (XPS), and X-ray Diffraction (XRD) was also performed to produce corrosion inhibition properties of TCPE in HCl solution. Inhibition efficiency and resistance polarization were figured out to increase with increasing concentration of the essential compound in TCPE. The Nyquist plot showed the charge transfer-resistant increase with increasing the inhibitor concentration. Energy activation and heat absorption from corrosion indicate that TCPE is absorbed on the steel surface. This absorption can occur through chemical impingement of inhibitor atoms or molecules on surfaces of metal. This phase is a spontaneous process and is followed by Langmuir isotherm absorption. Adsorption occurs at the surface in a mild steel surface is evidenced by the results of testing SEM-EDX, XPS, and XRD. It can be concluded that the addition of TCPE is very promising to be used in minimizing the rate of corrosion of mild steel.