DefinePK

Abstract

The high content of secondary metabolites in the cacao peels extracts, has the potential to be used as a corrosion inhibitor on mild steel. Effect of polar extract of cacao (Theobroma cacao) peels to the inhibition of corrosion, adsorption properties and mechanical properties in 1.5M HCl solution have been conducted on mild steel. Methods of weight loss, potensiodinamic dan impedance to determine the corrosion rate and efficiency of inhibition, as well as tensile and hardness testing for mechanical properties was conducted with the concentration of extract (0.5-2.5) % by an interval of 0.5%. The surface morphology of samples was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Energy dispersive X-ray spectroscopy (EDX) was used to examine the chemical composition of the surface. Corrosion rate is reduced and efficiency is increased with the increase in the concentration of the extract. The increase in the concentration of the extract is followed by an increase in mechanical properties, namely hardness, strength and fatigue strength. Chemical adsorption is characterized by an increased in the degree of surface of coverage with the rising levels of carbon in the surface of the mild steel with increasing concentrations of the extract. Adsorption isotherms are in accordance with the Langmuir adsorption. The presence of adsorption on the surface of the data is reinforced by EDX, X-ray photon spectroscopy) XPS and X-ray diffraction (XRD) AFM for topography. The addition of polar extract of cacao peels into HCl 1.5M solution is very effective to reduce the attack of corrosion on the surface of mild steel and it can retain mechanical properties of the mild steel after the corrosion.