Performance and computational studies of two soluble pyran derivatives as corrosion inhibitors for mild steel in HCl

The present study is aiming to explore the effect of 4-Hydroxy-6-methyl-3-(3-quinolin 8 yl acryloyl)pyran-2-one (HMQP) and 3-[3-(4-Dimethylamino-phenyl)-acryloyl]-4-hydroxy-6-methyl-pyran-2-one (DMPHP) on mild steel (MS) corrosion in acid solution (1 M HCI). The compound was tested at various concentrations (0.001-1 mM) and four temperatures (298, 308, 318, and 328 K) to determine the optimal concentration and temperature range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, weight loss measurement, potentiodynamic polarization measurement (PDP), electrochemical impedance spectroscopy, SEM/EDS and theoretical methods were used. The inhibition efficiencies increase with increase in concentration and decreases with temperature. The maximum inhibition efficiency was found 90% and 85.4% at 298 K in the presence of 1 mM of DMPHP and HMQP respectively. The experimental adsorption data obeyed the Langmuir isotherm model. The polarization parameters suggest that DMPHP and HMQP are mixed type inhibitors. The results of the EIS study suggest that these compounds inhibit corrosion by adsorption mechanism. A good correlation between theoretical and experimental results was obtained. (C) 2019 Elsevier B.V. All rights reserved.