Experimental and theoretical studies on corrosion inhibition of 4-amidinophenyl-2,2′-bifuran and its analogues in acidic media

Corrosion inhibition studies of carbon steel (CS) in 1 M HCl by newly synthesized bichalcophene compounds namely; 4-(2,2 '-bifuran-5-yl) benzamidine (MA-0947) and 6-(2,2 '-bifuran-5-yl) nicotinamidine (MA-0941) and 6-[5-(thiophen-2-yl) furan-2-yl] nicotinamidine (MA-0940) have been conducted using chemical and electrochemical methods. MA-0940 exhibited the highest inhibition efficiency % eta = 95% at 18 x 10(-6) M. The adsorption and thermodynamic activation parameters were calculated and discussed. Potentiodynamic polarization (PP) studies showed that the investigated compounds act as mixed-type inhibitors and chemically adsorbed on CS surface following the Langmuir adsorption isotherm. The surface morphology was analyzed using Atomic Force Microscopy (AFM). The effect of molecular structure on the inhibition efficiency has been explored by quantum chemical computations. The relation between the inhibition efficiency and some quantum parameters has been discussed and obvious correlations were observed. The binding energies of tested bichalcophene derivatives on Fe (110) surfaces were calculated using molecular dynamics simulation. The adsorption energies between metal surface and investigated bichalcophenes followed the order: MA-0940 > MA-0941 > MA-0947 and this order is in good agreement with the experimental data.