Basak Dogru Mert, Mehmet Erman Mert, Gülfeza Kardas and Birgül Yazici
The purpose of this paper is to investigate the adsorption and corrosion inhibition of two isomeric compounds (C4H5N3) as aminopyrazine (AP) and 2-amino-pyrimidine (2AP) on mild…
Abstract
Purpose
The purpose of this paper is to investigate the adsorption and corrosion inhibition of two isomeric compounds (C4H5N3) as aminopyrazine (AP) and 2-amino-pyrimidine (2AP) on mild steel (MS) in 0.5 M HCl. The study was a trial to combine experimental and modelling studies and research effect of molecular geometry on inhibition effect of inhibitor molecules.
Design/methodology/approach
The thermodynamic, kinetic and quantum parameters were determined. The electrochemical impedance spectroscopy and anodic polarisation measurements were obtained. The scanning electron microscope was used for monitoring electrode surface. The highest occupied molecular orbital, energy of the lowest unoccupied molecular orbital, Mulliken and natural bonding orbital charges on the backbone atoms, absolute electronegativity, absolute hardness were calculated by density functional theory (DFT)/B3LYP/6-311G (++ d,p).
Findings
Results showed that AP and 2AP suppressed the corrosion rate of MS. The corrosion current values were 0.530, 0.050 and 0.016 mA cm-2 in HCl, AP and 2AP containing HCl solutions, respectively. It was illustrated with the blocked fraction of the MS surface by adsorption of inhibitors which obeyed the Langmuir isotherm. The inhibition efficiency follows the order: 2AP > AP which is in agreement with experimental and quantum results.
Originality/value
This paper provides lay a bridge on the molecular geometry and inhibition efficiency by electrochemical tests and modelling study. The inhibition effect of AP and 2AP has not been compared with each other, neither experimentally nor theoretically. This study put forward possible application of 2AP as corrosion inhibitor especially for closed-circuit systems.
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Resit Yildiz and Basak Dogru Mert
This paper aims to study inhibitory effect of 4-aminothiophenol on the corrosion of mild steel (MS) in 0.5 M HCl.
Abstract
Purpose
This paper aims to study inhibitory effect of 4-aminothiophenol on the corrosion of mild steel (MS) in 0.5 M HCl.
Design/methodology/approach
In this study, electrochemical experiments, quantum chemical calculations, potentiodynamic measurements, linear polarization resistance and scanning electron microscopy were used.
Findings
The experimental results suggest that this compound is efficient corrosion inhibitor and the inhibition efficiencies increase with increasing their (from 0.5 to 10.0 mM.) concentrations. This reveals that inhibitive actions of inhibitors were mainly due to adsorption on mild steel surface. The adsorption of these inhibitors was found to obey Langmuir adsorption model. The computed quantum chemical features show good correlation with empirical inhibition efficiencies.
Originality/value
The 4-aminothiophenol is suitable inhibitor for application in closed-circuit systems against corrosion. The study is original and has great impact in industrial area. The obtained theoretical results have been adapted with the experimental data.