Synergistic Inhibitive Effect And Related Quantum Chemical Parameters Of 2-ethoxy-4,6- Dimethylnicotinonitrile And Iodide Ions On Corrosion Of Mild Steel In Sulfuric Acid | 35009
Journal of Material Sciences & Engineering
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The effect of iodide ions on the inhibitive performance of 2-ethoxy-4,6-dimethylnicotinonitrile (EDNN) in
0.5 M H2SO4 for mild steel (MS) corrosion has been studied using gravimetric, electrochemical impedance
spectroscopy (EIS) and potentiodynamic polarization measurements. EDNN inhibits the corrosion of MS and
its inhibition efficiency increases on increasing the concentration of the inhibitor at 298 K. The adsorption of
EDNN on MS leading to inhibition was found to follow the Langmuir adsorption isotherm. The inhibition
efficiency of EDNN increased on the addition of 2.0 mM KI. The synergistic effect of KI was determined by
calculating the synergism parameters. The value of synergism parameter which is more than unity indicates
the fact that the enhanced inhibition efficiency in the presence of iodide ions is only due to synergism. This
synergism showed that a cooperative mechanism exists between the iodide anion and EDNN cations. The
increase in surface coverage in the presence of iodide ions indicates that iodide ions enhance the adsorption
of EDNN on the negatively charged metal surface. Surface morphology of corroded / inhibited MS has been
studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). X-ray photoelectron
spectroscopy (XPS) of the inhibited MS surface has been carried out to determine the composition of the
adsorbed surface film. Some quantum chemical parameters and the Mulliken charge densities for EDNN were
calculated by the density functional theory (DFT) method to provide further insight into the mechanism of
inhibition of the corrosion process.
Punita Mourya received the B.Sc. degree and M.Sc. degree from Veer Bahadur Singh Purvanchal University, Jaunpur, Uttar Pradesh, India, in 2007 and 2009, respectively. She is currently working towards the Ph.D. degree in the Department of Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi, India. She is the senior research fellow of the UGC, India. She has five publications in international journals. Her present research interests include inhibition of acid corrosion of mild steel using heterocyclic organic compounds.