Experimental and surface morphological study of corrosion inhibition of N80 carbon steel in HCl stimulated acidizing solution using gum exudate from Terminalia Mentaly

Abstract

The gum exudate from Terminalia Mentaly (GETM) was investigated for corrosion inhibition of N80 carbon steel in 1 M HCl solution using electrochemical and gravimetric measurements. GETM was found to be a good inhibitor for N80 steel corrosion in the 1 M HCl stimulated acidizing solution, affecting both cathodic and anodic reactions. The inhibition efficiency of GETM increased as the concentration increases but decreased with rise in temperature. Maximum inhibition efficiencies of 92.4%, 95.5% and 92.5% were obtained from electrochemical impedance spectroscopy (EIS), gravimetric and potentiodynamic polarization studies respectively, at 2.0 g/L GETM in 1 M HCl. Adsorption of GETM at the studied temperatures was found to follow Langmuir and Temkin isotherms and the action of inhibition suggests both physical and chemical adsorption on the metal surface. It was found from polarization study that GETM is a mixed type inhibitor but slightly acted more like an anodic inhibitor. EIS studies revealed that GETM increased the charge transfer resistance while diminishing the double layer capacitance with increasing concentration due to the formation of protective film on the steel. Surface morphological study performed using scanning electron microscopy (SEM) confirmed the formation of protective film of GETM on the N80 steel surface.