Corrosion Inhibition of Mild Steel in 1M HCL by Ethanolic Stem Extract of Caralluma DalzielII N.E. BR.: Potentiodynamic Polarization and Adsorption Analysis
Hussaini A.
Siaka A. A.
Gafar M. K.
Abstract
The corrosion inhibition performance of the ethanolic stem extract of Caralluma dalzielii N.E. Br. (commonly known as Mosque reed) in 1 M HCl solution was investigated using potentiodynamic polarization. The inhibition efficiency of the extract was evaluated at 303 K and 333 K. Gas Chromatography–Mass Spectrometry (GC–MS) analysis revealed the presence of twenty (20) compounds in the extract, several of which contain heteroatoms (S, O) that are responsible for the corrosion inhibition effect. The functional groups present in the plant extract were further examined and identified by Fourier Transform Infrared (FTIR) spectroscopy. SEM/EDX shows the surface morphology and the elemental composition before and after the inhibition which directly support the electrochemical results. The results of the study showed that Caralluma Dalzielii extract effectively inhibited the acid corrosion of mild steel at different concentrations. The inhibition efficiency values at 303 K were: 0% (blank), 67.2% (200 ppm), 76.7% (400 ppm), 80.0% (600 ppm), and 81.0% (800 ppm). At 333 K, the efficiencies were: 0% (blank), 76.2% (200 ppm), 78.2% (400 ppm), 79.3% (600 ppm), and 84.4% (800 ppm). The inhibition efficiency increased with increasing inhibitor concentration at both temperatures. The adsorption of the inhibitor on the mild steel surface was found to follow the Langmuir adsorption isotherm, and the mechanism was dominated by physisorption.
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