ISSN 2305-6894

A combined experimental and theoretical study of (E)-ethyl 3-(4-methoxyphenyl)acrylate as corrosion inhibitor of iron in 1 M HCl solutions

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1 Chemistry Education Division, Faculty of Science Education, University of Mataram, Jalan Majapahit no 62 Mataram, 83125, Indonesia
2 Department of Chemistry, Faculty of Mathematics and Natural Science, University of Jalan Majapahit no 62 Mataram. Mataram, 83125, Indonesia
3 Department of Chemistry, Universitas GadjahMada, Sekip Utara, Yogyakarta 55281, Indonesia
4 Department of Chemistry, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung. Jalan Ganesha No 10 Bandung, 40132, Indonesia

Abstract: The study aimed to isolate, characterize and measure the corrosion inhibition efficiency of (E)-ethyl 3-(4-methoxyphenyl)acrylate (EPE) from Kaempferia galanga extract of iron in 1 M HCl solution. The experimental study was conducted with weight loss and electrochemical impedance measurements followed by theoretical study using density functional theory (DFT) method at the B3LYP level of theory. EPE has been successfully isolated and confirmed by spectroscopic techniques. Thermodynamic parameters: activation energy Ea, adsorption enthalpy ΔH, entropy ΔS, and Gibbs-free energy of adsorption ΔG0ads indicate physisorption mechanism. The adsorption of EPE on the iron surface follows Temkin’s isothermal. It was revealed that the efficiency of corrosion inhibitor of EPE at the maximum tested concentration was 76.22%. Density functional theory (DFT) calculation of EPE was applied to compare the effect of electron donating and withdrawing groups on the efficiency of corrosion inhibitors, as an approach for designing high-efficiency new corrosion inhibitors. The corrosion inhibition performance of the EPE and its derivatives was evaluated using quantum chemical parameters such as frontier orbital energies (EHOMO, ELUMO), ionization potential (I), electron affinity (A), absolute electronegativity (χ), the fraction of electrons transferred (ΔN), corrosion inhibition efficiency (IE%), and binding energy (ΔE). The study shows that the corrosion inhibition efficiency of EPE increases with the addition of the NH2 function group whereas the NO2 group gives the opposite result.

Keywords: corrosion inhibition, Kaempferia galanga extract, DFT

Int. J. Corros. Scale Inhib., , 7, no. 4, 633-647 PDF (1 124 K)
doi: 10.17675/2305-6894-2018-7-4-10

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