Journal
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
Volume 76, Issue -, Pages 109-126Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.physe.2015.10.005
Keywords
Mild steel; Polarization; Mixed-type Inhibition; Quantum Chemical Calculations
Funding
- National Research Foundation (NRF) of South Africa
- NRF/Sasol Inzalo Foundation
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The corrosion inhibition potential of four quinoxaline derivatives namely, 1-[3-(4-methylphenyl)-5-( quinoxalin-6-yl)-4,5-dihydropyrazol-1-y]butan-1-one (Me-4-PQPB), 1-(3-(4-methoxyphenyl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl)butan-1-one (Mt-4-PQPB), 1-[3-(3-methoxyphenyl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl]butan-1-one (Mt-3-PQPB) and 1-[3-(2H-1,3-benzodioxol-5-yl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl]butan-1-one (Oxo-1,3-PQPB) was studied for mild steel corrosion in 1 M HCI solution using electrochemical, spectroscopic techniques and quantum chemical calculations. The results of both potentiodynamic polarization and electrochemical impedance spectroscopic studies revealed that the compounds are mixed-type inhibitors and the order of corrosion inhibition efficiency at 100 ppm is Me-4-PQPB > Mt-3-PQPB > Oxo-1,3-PQPB > Mt-4-PQPB. Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopic analyses confirmed the presence of chemical interactions between the inhibitors and mild steel surface. The adsorption of the inhibitor molecules on mild steel surface was found to be both physisorption and chemisorption but predominantly chemisorption. The experimental data obey Langmuir adsorption isotherm. Scanning electron microscopy studies revealed the formation of protective films of the inhibitors on mild steel surface. Quantum chemical parameters obtained from density functional theory (DFT) calculations support experimental results. (C) 2015 Elsevier B.V. All rights reserved.
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