Green Inhibitor for Mild Steel in Acidic Solution by Using Crude Extract and Polar Extract of Theobroma cacao Peels

Abstract

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% and 92.08% (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.

Secondary Plant Metabolites of Natural Product Origin—<i>Strongylodon macrobotrys</i> as Pitting Corrosion Inhibitors of Steel around Heavy Salt Deposits in Gabu, Nigeria

“…It also shows that the inhibitors are physically adsorbed on the metal surfaces. The regression values (R 2 ) were very close to unity, an indication revealing the good fitting of the data to the isotherm and the fact that all the adsorbed inhibitor molecules are in contact with the surface layer of the adsorbent (mild steel)[42] [43][44] [56][59]. The slope value for the Langmuir plots is greater than unity, indicating a strong relationship between the species adsorbed.…”

“…Consequently, the inhibitor therefore has the potential of increasing the energy of the intermediate, reduce the number of collisions, reduce the number of particles that have enough energy to react and also reduce the number of corrosion reaction particles with the correct orientation, thereby slowing the transition from the reactants to the products (rate of reaction) at a given temperature[19] [37][40]. It can also mean a physical adsorption following the large increase values of the activation energy in the inhibited solution compared to that of the control and values also been less than 20 kJ/mol which is the threshold for phisisorption[22] [57] [58][59].Thermodynamic parameters for the adsorption of studied inhibitors were determined through transition state Equation(10) [21] [22] [23] [47][49].…”

Adsorption Effect of Theobroma Cacao Extract On Steel Surface to Protect Corrosion Rate

“…Giving inhibitors is one of the effective methods for controlling corrosion because it is considered more economical, effective and its application is quite easy, so it is widely applied in the industrial world [3]. Organic inhibitors are more widely used because they are cheap and easy to obtain, environmentally friendly and non-toxic compared to inorganic inhibitors [4].…”

Investigation of the Adsorption Characteristics of <i>Theobroma cacao</i> Peels Biomass Inhibitors on Mild Steel Surfaces by EIS, SEM-EDX, XPS, and Chemical Studies in Acidic Media

“…TCPE contains chemical compounds, including a mixture of flavonoids or condensed tannins such as anthocyanins, tannins, catechins, and leucoanthocyanidin [21][22]. These compounds can form coordinating covalent bonds because they have a heteroatom group that can donate electrons [23].…”