The effect of some green inhibitors on the corrosion rate of Cu, Fe and Al metals

Abstract

Inhibition of metal corrosion is a very important and challenging issue environmentally. The use of corrosion inhibitors is an effective method to reduce the corrosion rate of several metals. In this regard, researchers have used a wide range of corrosion inhibitors for several decades to minimize the damages arising in corrosive environments. Density functional theory (DFT) calculations with B3LYP/6-31G* (d,p) level have been performed on APDTC, CMI, HPMA, PASP and PESA as a green source of environmentally friendly corrosion inhibitors for Cu, Fe and Al metals. Global quantum parameters of inhibitors and thermodynamic Gibbs function (ΔGads) of adsorption of metals have been calculated and used to investigate the efficiency of each corrosion inhibitor. Our results showed that APDTC exhibits the highest anti-corrosion efficiency among all compounds with Cu, Fe and Al metals showing remarkable inhibition efficiency with Cu comparing with Fe and Al. APDTC exhibit the highest electrophilicity index (ω) values compared to other inhibitors and it effect on the metals in the order: Cu > Fe > Al. The distinguished corrosion inhibition of APDTC is explained by its unique high electrophilicity power and Gibbs free energy of adsorption value on metal surface (ΔGads). The HOMO and LUMO gap (ΔEgap) of the inhibitors increases in polymers in the order: HPMA > CMI > PESA > PASP > APDTC. These results show excellent agreement with recent published work.