Adsorption and Thermodynamic Characteristics of Plumeria rubra Plant Extracts on Mild Steel Corrosion in Industrial Water Medium
C. B. Pradeep Kumar
Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore- 570 006, India
K. N. Mohana *
Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore- 570 006, India
*Author to whom correspondence should be addressed.
Abstract
The inhibition effect of Plumeria rubra (PR) extracts on the corrosion of mild steel in industrial water medium was studied by mass loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The results show that the protection efficiency increased with increase in inhibitor concentration and decreased with temperature. Electrochemical impedance spectroscopic measurements indicated that charge transfer resistance increases with increasing inhibitor concentration. The adsorption of PR extracts on mild steel surface obeys Langmuir isotherm model. Potentiodynamic polarization studies revealed that PR extracts act as a mixed-type inhibitor. Scanning electron microscopy (SEM) was used to analyze the surface adsorbed film.
Keywords: Mild steel, industrial water, Plumeria rubra, polarization, EIS