Cardiospermum halicacabum leaves extract as a green corrosion inhibitor for mild steel in simulated oil well water medium

The green corrosion inhibition properties of an aqueous extract of Cardiospermum halicacabum leaves (CHL) were studied on mild steel (MS) in simulated oil well water (SOWW) medium by weight loss method and potentiodynamic polarization study.The active principle components are characterized by Fourier Transform Infrared Spectroscopy (FTIR).The surface morphology is examined with the help of scanning electron microscopy (SEM) and the surface roughness analysis is done by atomic force microscopy (AFM).Weight loss method reveals that as the concentration of inhibitor increases, the corrosion rate decreases and inhibition efficiency increases.A maximum corrosion inhibition efficiency of 99% is offered by the inhibitor system.Potentiodynamic polarization study shows that CHL acts as mixed type of inhibitor, controlling anodic reaction and cathodic reaction to an equal extend.This is confirmed by the fact that the shift in corrosion potential in presence of inhibitor is very small, that is, -13 mV vs. SCE.Protective film formation against corrosion was confirmed by Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) studies.In presence of inhibitor a protective film is formed, which is found to be very smooth when compared with the uninhibited system.Rootmean-square roughness, average roughness and peak-to-valley height value for the protective film are found to be lower than those of unprotected metal surface.The results show that the CHL extract could serve as good green corrosion inhibitor for mild steel immersed in simulated oil well water.The outcome of the study may find application in petroleum industry.