Experimental and Theoretical Studies of One Dihydropyridine Derivative as Corrosion Inhibitor in Acidic Media

A new organic compound, namely dihydropyrimido [4,5-b][1,6] naphthyridine-2,4, 6, 8(1H,3H,7H,9H)-tetraones with amino acid moiety (DHPN) was synthesized and characterized by 1H, 13C Nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy experiments.  DHPN was investigated for the first time as a green inhibitor of mild steel (A105) corrosion in acidic (0.1, 0.5 mol L-1 H2SO4 and HCl) solutions using potentiodynamic polarization technique. The results showed that, inhibition efficiency increased with the inhibitor concentration within the range of 0.95-19 mg L-1. The polarization curves demonstrated that, this compound act as a mixed type inhibitor. The adsorption of the DHPN molecule on the surface of mild steel was found to obey the Langmuir adsorption isotherm. Besides, data processing methods like support vector machine modelling was performed to prove the relationship between inhibitory effect and molecular structure.