Thermodynamic study of corrosion inhibition of mild steel in corrosive medium by Piper nigrum extract

Abstract

Background/Objectives: Introduction of green corrosion inhibitor can stop the use of expensive and harmful synthetic inhibitor. This study investigates the corrosion inhibition of mild steel in aggressive media by using Piper nigrum extract. Methods/Statistical Analysis: The potentiality of Piper nigrum to inhibit corrosion was studied based on concentration of inhibitors range of 0.2g/l-0.5g/l and temperature range of 40°C-60 °C by using gravimetric and thermometric methods. Results: Calculation from weight loss method revealed that Inhibition Efficiencies (IE%) increase with increasing inhibitor concentration which show a decrease in Corrosion Rate (CR). However, the rise in temperature decreases the IE% which means an increasing in the CR. Furthermore, thermodynamic parameters of adsorption process such as Activation Energy (Ea), Enthalpy (ΔH° ) and Entropy (ΔS° ) were calculated and these values showed a good interaction. A rise of Ea values with increasing inhibitor concentration proved a physical adsorption mechanism is taking place. The ΔH° calculated proved that this is an endothermic process. Conclusion/Application: Results from this study showed that Piper nigrum was an attractive alternative to prevent corrosion as it shows the great inhibition efficiency.