The corrosion inhibition performance of pectin with propyl phosphonic acid and Zn2+ for corrosion control of carbon steel in aqueous solution
A protective film has been formed on the surface of carbon steel in neutral aqueous environment using a synergistic mixture of an ecofriendly inhibitor, viz. pectin, along with propyl phosphonic acid (PPA) and Zn2+ ions. The inhibitive effect of pectin, PPA, and Zn2+ ions has been investigated by gravimetric studies, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The investigations revealed that pectin acts as an excellent synergist in corrosion inhibition. Optimum concentrations of all three components of the ternary formulation have been established by gravimetric studies. EIS and potentiodynamic polarization techniques have been employed to determine the nature of the inhibition process of the selected compounds. EIS studies of the metal–solution interface indicated that the surface film is highly protective against the corrosion of carbon steel. The results of potentiodynamic polarization revealed that the formulations are of mixed type (anodic and cathodic). Further, to characterize the protective film formed on the iron substrate, Fourier-transform infrared spectroscopy, atomic force microscopy (AFM), scanning electron microscopy, and X-ray photoelectron spectroscopy analytical techniques were employed. Based on the results obtained, a suitable mechanism of corrosion inhibition is presented.
KeywordsPectin Propyl phosphonic acid Carbon steel Corrosion Polarization Impedance
M. Prabakaran is grateful to the UGC for a Research Fellowship in Sciences for Meritorious Students. The authors thank the Co-ordinator, UGC-SAP, Department of Chemistry, GRI for providing the support for recording XPS and also the authorities of Gandhigram Rural Institute for encouragement.
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