Abstract
Corrosion inhibition effect of Sesbania sesban extract (SSE) on the carbon steel in 1M HCl solution was investigated by potentiodynamic polarization and weight loss techniques. The corrosion rate of carbon steel was decreased in the presence of SSE. The corrosion inhibition efficiency was found to increase with SSE concentration to attain 91.08% with 2.00 g/l at 25℃. The polarization studies showed that SSE acts as mixed type inhibitor. The effect of temperature, acid concentration and immersion time on the corrosion rate of carbon steel in HCl solution in the absences and presence of SSE was also studied. Values of corrosion inhibition efficiency calculated from weight loss technique were in good agreement with those obtained from potentiodynamic polarization test. The results showed that the adsorption of the extract on the carbon steel surface obeys Langmuir isotherm. The activation parameters, apparent activation energy (Ea), the enthalpy of activation (ΔHa) and entropy of activation (ΔSa) for the corrosion of carbon steel in 1M HCl in the absence and presence of SSE were calculated and discussed.
Highlights
Metallic materials are still the most widely used group of materials in both mechanical engineering and the transportation industry
The electrochemical parameters, anodic Tafel constant (β ), cathodic Tafel constant (β ), corrosion potential (E ), corrosion current density (i ) and the corresponding inhibition efficiency which was calculated from equation 1 for the corrosion of carbon steel in 1M HCl solution without and with different concentrations (0.4 – 2 g/l) of SSEat 25 are illustrated in table 1
The corrosion current density of carbon steel in 1M HCl solution reduced from 231.98μA/cm to 20.96 and the corrosion inhibition efficiency increased to 91.08% in the presence of 2 g/l of SSE at 25
Summary
Metallic materials are still the most widely used group of materials in both mechanical engineering and the transportation industry. Most metals are inherently unstable and it is their natural tendency to seek self-destruction by reacting with their environment to attain a state of lower energy by forming a metal compound. This is the state in which the majority of metals are found in nature (Haward, 1968). Plants represent a class of interesting source of compounds currently being exported for use in metal corrosion protection in most systems. The present study aimed at investigating the inhibitive properties of ethanol extract of Sesbaniasesban plant leaves on the corrosion of carbon steel in 1M HCl solution
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