Experimental and Theoretical Evaluation of new Quinazolinone Derivative as Organic Corrosion Inhibitor for Carbon Steel in 1M HCl Solution

The inhibiting action of newly synthesised quinazolinone derivative namely 2- [ (3-phenyl-4-oxo-3, 4-dihydroquinazolinone-2-yl-thio) aceto] thiosemicarbazide (POQS), towards carbon steel corrosion in 1M HCl has been investigated at various concentration and different temperature using potentiodynamic polarisation, Scanning Electron Microscopy (SEM) and Energy Dispersion Spectroscopy (EDS) measurements. Polarisation curves showed that the compound acts as a mixed inhibitor, and the adsorption of the evaluated inhibitor obeys the Langmuir adsorption isotherm. SEM plots indicated that the presence of the inhibitor decreases the corrosion process of carbon steel in 1M HCl. Theoretically quantum mechanics calculations of the approximate semiempirical method PM3 and Density Functional Theory DFT of (B3LYP) with a 6-311++G (2d, 2p) by using Gaussian-09 program were done to evaluate the structural, electronic and reactivity parameters of (POQS) in relation to their effectiveness as a corrosion inhibitor in vacuum and two liquid media (DMSO and H2O) The calculated physical properties and quantum chemical parameters correlated to the inhibition efficiency all are studied and discussed at the equilibrium geometry.