Corrosion control Research Papers - Academia.edu (original) (raw)

Quantum chemical calculations, molecular dynamics simulation and experimental studies of using some azo dyes as corrosion inhibitors for iron. Part 1: Mono-azo dye derivatives
Loutfy H. Madkour a , ∗, Sava ¸s Kaya b , Cemal Kaya b , Lei Guo c
a Chemistry Department, Faculty of Science and Arts, Baljarashi, Al-Baha University, P.O. Box 1988 Al-Baha, Saudi Arabia b Cumhuriyet University, Faculty of Science, Department of Chemistry, 58140 Sivas, Turkey c School of Material & Chemical Engieering, Tongren University, Tongren 554300, PR China
This study consists of two parts. In the first part, the inhibitive performance of six mono-azo dye (MAD_ 1 –6 ) derivatives was investigated experimentally (gravimetric, thermometric, UV–visible spec- trophotometric and electrochemical potentiostatic methods) and computationally against corrosion of Fe metal in 2 M HNO 3 and 2 M NaOH solutions. Density functional theory (DFT) calculations and molec- ular dynamics simulation (MDS) approach were performed. Quantum chemical parameters such as the highest occupied molecular orbital energy ( E HOMO ), lowest unoccupied molecular orbital energy ( E LUMO ), the energy gap between E LUMO and E HOMO ( E ), dipole moment ( D ), chemical hardness ( η), softness ( σ), electronegativity ( χ), proton affinity, global electrophilicity ( ω), global nucleophilicity ( ε) and total energy (sum of electronic and zero-point energies) were calculated and discussed with the help of HF/SDD, HF/6- 311 G, HF/6-31 ++ G, B3LYP/SDD, B3LYP/6-311 G and B3LYP/6-31 ++ G methods. Polarization measurements indicate that (MAD) compounds are of mixed-type inhibitor in acidic, act mainly as cathodic in alkaline solution. Kinetic model involving binding constant ( K b ), active sites ( 1/y ) and standard free energy values of adsorption ( G o ) were compared with the parameters of equilibrium constant ( K ads ), lateral interac- tion ( f ) and ( G o ), that obtained from Frumkin adsorption isotherm model. Then, we calculated binding energies on Fe (110) surface of the inhibitors. The theoretical data obtained are in good agreement with the experimental inhibition efficiency results. ©2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.