Computational studies of the corrosion‐inhibition efficiency of iron by triazole surfactants

Abstract

The corrosion-inhibition efficiency of N-decyl-1,2,4-triazole, N-undecyl-1,2,4-triazole, and N-dodecyl-1,2,4-triazole surfactants and the corresponding protonated molecules have been studied computationally using density functional theory and secondorder Møller-Plesset calculations. Corrosion-inhibition properties and the strength of the affinity of the iron-surfactant molecules were estimated by using an appropriate cluster model. The ironsurfactant complexes were constructed by attaching the triazole ring to the iron surface modeled by one and five iron atoms, respectively. Relations between molecular properties and corrosion-inhibition efficiency were determined by using linear regression and quantitative structure-activity relationship (QSAR). The QSAR analysis yielded significant correlations between the corrosion-inhibition activity of the studied molecules with molecular properties such as the highest occupied molecular orbital, the lowest unoccupied molecular orbital, dipole moments (l), and the total atomic charges. Fukui indexes were also calculated for assessing correlations between them and experimental corrosion-inhibition efficiencies. Solvent effects were investigated by using the polarized continuum model. The effects of the acidity medium and the local reactivity of the triazole derivatives with iron were also analyzed. The calculated binding energy of 276 kJ/mol for the Fe 5 -N-dodecyl-1,2,4-triazole cluster shows that the surfactant molecules bind strongly to iron surfaces, which is in agreement with experimental data.

Galactomannan as a new bio-sourced corrosion inhibitor for iron in acidic media

“…According to the RDF calculation result, the first peak at 2.5 Å indicates chemisorption interactions and for the peaks above 3.5 Å are associated to the physical interactions, that explain the capacity of the biopolymer to stop the dissolution of metal by the ability of the biopolymer molecules to give his electrons to the metal and vice versa. This result conformed to the isotherm adsorption result [41,42].…”

“…From the distribution of the inhibitor's HOMO and LUMO frontier orbital (Figure 12), it is clear that the distribution of HOMO and LUMO density is located on the oxygen atoms, these sites are responsible for giving electrons to the metal surface [42]. The differences between E LUMO of Galactomannan and E HOMO of iron (E2) and vice versa (E1) were therefore determined and shown in Figure 12.…”

DFT Modelling of the Electronic Structure and Stabilities of (Sb2O5.nH2O) Clusters towards Cysteine, Glucose and Trypanothione Complexation

“…plays an essential role in the inhibition process. When, the HOMO-LUMO energy levels difference between donor and acceptor is lower, this is opportune to realize a good inhibition for the studied system [40,41]. Also, the HOMO-LUMO wave function localization given at DFT-D3 contributes to make an overlapping through H-atom mobility leading a good interaction surface/substrate thorough (HOMO donor and LUMO acceptor and vice versa.…”

“…Cluster models have drawn great attention due to their fundamental interest in basic research as well as the possibility of constructing nanostructured materials using such clusters as building blocks [37][38][39][40][41]. To simulate the inhibitor molecules effect using large cluster and large molecules in the antimony oxide interaction, calculations were performed on the big cluster/dipeptide.…”

“…To simulate the inhibitor molecules effect using large cluster and large molecules in the antimony oxide interaction, calculations were performed on the big cluster/dipeptide. This theoretical approach has also been used in our previous studies of the interaction of organic molecules with oxides surfaces [40][41][42][43] repectively. Also between the two computed functional, the correlation implies a decreasing of bonds and angles and agreeing the X-Ray data [18].…”